FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
COMPRESSOR, AIR-CONDITIONING APPARATUS, REFRIGERATION APPARATUS,
AND COMPRESSOR CONTROL METHOD;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI
2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Title of Invention
COMPRESSOR, AIR-CONDITIONING APPARATUS, REFRIGERATION APPARATUS,
AND COMPRESSOR CONTROL METHOD
5
Technical Field
[0001]
The present disclosure relates to a compressor driven by an electric motor, an
air-conditioning apparatus including the compressor, a refrigeration apparatus including
10 the compressor, and a compressor control method for controlling the compressor.
Background Art
[0002]
Many of failures of existing compressors are caused by a seizure or abnormal
wear in a sliding bearing. As an example of an existing compressor, there is a
15 refrigerant compressor including a viscosity sensor to keep a bearing of the refrigerant
compressor from suffering seizure damage due to a reduction in the viscosity of
lubricating oil. This sensor measures viscosity in an oil sump of the refrigerant
compressor and the supply of refrigerant to the refrigerant compressor is stopped when
the viscosity is below a predetermined value. In this technique, when the supply of
20 refrigerant is stopped, a load on the compressor is temporarily reduced to keep the
compressor from seizing up (see, for example, Patent Literature 1).
Citation List
Patent Literature
[0003]
25 Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2002-206486
Summary of Invention
Technical Problem
[0004]
3
In existing compressors, although viscosity in an oil sump of a compressor is
measured, it is difficult to fully determine the contact or seizure between a shaft and a
bearing based on the viscosity in the oil sump. Even when the viscosity is not less
than the predetermined viscosity, in some operating conditions, there is a possibility that
5 the shaft may come in contact with the bearing to cause a seizure or abnormal wear.
Furthermore, refrigerant is not supplied and thus the compressor ceases to function,
resulting in a reduction in efficiency.
[0005]
To address such issues, it is intended that a failure in a bearing portion is avoided
10 in a wide range of operating conditions.
Solution to Problem
[0006]
In an embodiment of a claim of the present disclosure, there are included a
sensor provided at a sliding bearing or a rotating shaft portion, into which the sliding
15 bearing is fitted, the sensor being configured to output a measured measurement value
as an output signal, and a signal processing unit configured to perform an arithmetic
operation on the output signal output from the sensor to obtain a rotation speed at which
an electric motor is to rotate and configured to transmit the rotation speed as a control
signal to the inverter to control a rotation speed of the electric motor.
20 Advantageous Effects of Invention
[0007]
In an embodiment of the present disclosure, a failure in a bearing portion can be
avoided in a wide range of operating conditions. Furthermore, in another embodiment
of the present disclosure, contact between the rotating shaft and the bearing portion of a
25 compressor, and a seizure and abnormal wear involved in this contact can be avoided
without stopping the operation of the compressor.
Brief Description of Drawings
[0008]
[Fig. 1] Fig. 1 illustrates a configuration of a compressor representing
30 Embodiment 1 of the present disclosure.
4
[Fig. 2] Fig. 2 illustrates a flow of control of the compressor representing
Embodiment 1 of the present disclosure.
[Fig. 3] Fig. 3 illustrates an example of a flow of control of a rotation speed of the
compressor representing Embodiment 1 of the present disclosure.
5 [Fig. 4] Fig. 4 is a schematic diagram illustrating a state in which a rotating shaft
in a sliding bearing of the compressor representing Embodiment 1 of the present
disclosure is eccentric.
[Fig. 5] Fig. 5 illustrates a configuration in which a displacement sensor is
provided at a rotating shaft portion fitted into the sliding bearing of the compressor
10 representing Embodiment 1 of the present disclosure.
[Fig. 6] Fig. 6 illustrates a configuration of the compressor representing
Embodiment 2 of the present disclosure.
[Fig. 7] Fig. 7 illustrates an example of a configuration of hardware of a
calculating machine that controls the compressor representing Embodiment 2 of the
15 present disclosure.
Description of Embodiments
[0009]
Embodiment 1.
Fig. 1 is a vertical cross-sectional view illustrating a refrigerant compressor
20 according to Embodiment 1 of the present disclosure. Although a refrigerant
compressor is taken as an example of a compressor here, a compressor to which
Embodiment 1 can be applied is not limited to the refrigerant compressor and may be
any compressor, such as a compressor or blower, that has a typical sliding bearing.
Embodiment 1 can be applied particularly to a compressor that has a rotation
25 mechanism rotating around a rotating shaft supported by a sliding bearing and that
performs a compression function by using the rotation mechanism. Furthermore,
Embodiment 1 is suitable for a compressor in which an eccentric load is applied on a
rotating shaft of a rotation mechanism.
[0010]
5
Fig. 1 illustrates a configuration of a compressor representing Embodiment 1. In
Fig. 1, a cross-sectional view of a twin rotary compressor, which is one of refrigerant
compressors, is illustrated on the left-hand side, and a block representing a
configuration that controls this compressor is illustrated on the right-hand side.
5 Although the twin rotary compressor is illustrated here, a single rotary compressor in
which one compressor mechanism is provided may be provided. Alternatively, the
present disclosure can be applied to any compressor, such as a scroll compressor or
screw compressor, supported by a bearing.
[0011]
10 In Fig. 1, a refrigerant compressor 6 includes a rotating shaft 1, sliding bearings 2
that support the rotating shaft 1, an electric motor 3 that causes the rotating shaft 1 to
rotate, and an inverter 4 that controls the electric motor 3. The electric motor 3 is
constituted by a stator 3a, and a rotor 3b provided inside the stator 3a and fixed to the
rotating shaft 1. The electric motor 3 rotates around a central axis of the rotating shaft
15 1 by using electromagnetic force generated between the stator 3a and the rotor 3b.
[0012]
Furthermore, at the rotating shaft 1, a rolling piston having a shape that is
eccentric with respect to the central axis of the rotating shaft 1 is provided. The rolling
piston is disposed in a cylinder provided in such a manner as to extend from the central
20 axis of the rotating shaft 1 in an outer circumferential direction. A compression
chamber and a suction chamber are formed between the rolling piston and the cylinder.
When the electric motor 3 rotates, the rolling piston fixed to the rotating shaft 1 rotates
inside the cylinder. As the rolling piston rotates, the suction chamber connected to a
suction port is reduced in space, an inner medium is compressed to provide the
25 compression chamber, and the compression chamber connects to a discharge port to
discharge the inner medium.
[0013]
The sliding bearings 2 support the rotating shaft 1 in such a manner as to enable
the rotating shaft 1 to rotate and can be disposed on the outer sides in axial directions
6
of two rolling elements disposed side by side in an axial direction of the rotating shaft 1.
In this case, the sliding bearings 2 may constitute end faces of compression chambers.
[0014]
Furthermore, the refrigerant compressor 6 includes a sensor 5 that is provided at
5 a sliding bearing 2 or a portion of the rotating shaft 1 into which the sliding bearing 2 is
fitted and that outputs, as an output signal, a measurement value obtained by
measuring a physical quantity representing the state of the refrigerant compressor 6 by
using scientific principles, and a signal processing unit 7 serving as a control unit that
performs an arithmetic operation on the output signal output from the sensor 5 to obtain
10 a rotation speed at which the electric motor 3 is to rotate and that transmits a control
signal to the inverter 4. Incidentally, the signal processing unit may be regarded as a
control unit.
[0015]
For the sensor 5, there is no difference between contact and non-contact
15 methods, and a physical quantity measured by the sensor 5 may be any physical
quantity representing the state of the refrigerant compressor 6 that can be measured
with the sensor 5 being provided at the sliding bearing 2 or the portion of the rotating
shaft 1 into which the sliding bearing 2 is fitted. Examples of a physical quantity
obtained by the sensor 5 include vibration, temperature, and pressure.
20 Measurement principles used in the sensor 5 are scientific principles. An acceleration
sensor for vibration, a thermocouple for temperature, and a diaphragm pressure sensor
for pressure are conceivable, as the sensor 5.
[0016]
More specifically, the sensor 5 can function as a displacement sensor can be
25 used as the sensor 5. The displacement sensor may be any sensor that can measure
a displacement, distance, thickness, or others of an object to be measured. For a
measurement method used in the displacement sensor, there is no difference between
contact and non-contact methods, and any of eddy-current, capacitive, laser, ultrasonic,
and other methods may be used. Furthermore, the displacement sensor may measure
7
a displacement of the sliding bearing 2, a relative displacement between the sliding
bearing 2 and the rotating shaft 1, or a change in the relative displacement.
[0017]
Next, operation will be described. When the electric motor 3 causes the rotating
5 shaft 1 to rotate, the rotor 3b fixed to the rotating shaft 1 rotates. Then, the
compressor 6 performs a cycle of suctioning, compressing, and discharging refrigerant
between the rotor 3b and the cylinder, thus performing a function of compressing and
discharging refrigerant.
[0018]
10 Here, the displacement sensor 5 that measures a bearing clearance between the
rotating shaft 1 of the rotor 3b of the compressor 6 and an inner surface of the sliding
bearing 2 outputs a signal, such as a voltage based on the magnitude of the bearing
clearance. A sensor signal representing the magnitude of the bearing clearance
between the rotating shaft 1 and the inner surface of the sliding bearing 2 is transmitted
15 to the signal processing unit 7, and the signal processing unit 7 converts the received
sensor signal into the magnitude of the bearing clearance. The signal processing unit
7 considers a rotation speed at which the electric motor 3 is to rotate in accordance with
the magnitude of the bearing clearance and outputs a control signal to the inverter 4.
The signal processing unit 7 may obtain a control signal to the inverter 4 in accordance
20 with the above-described sensor signal without converting the sensor signal into the
bearing clearance and output this control signal to the inverter 4.
[0019]
The signal processing unit 7 can perform the following operation in obtaining a
control signal based on the magnitude of the bearing clearance or the sensor signal. A
25 preset threshold value that is a criterion of soundness of a measurement value of the
sensor 5 is held. When a measurement value of the sensor 5 falls outside a
soundness range that is defined by a preset threshold value and in which soundness is
ensured, feedback control of a rotation speed of the electric motor 3 is performed so
that the measurement value of the sensor 5 falls within the soundness range.
30 [0020]
8
The threshold value can also be composed of two values of an upper limit
threshold value and a lower limit threshold value as criteria of soundness of a
measurement value of the sensor 5. In this example, when a measurement value of
the sensor 5 is a value in a range from the upper limit threshold value to the lower limit
5 threshold value, the measurement value falls within a soundness range representing
that the state of the compressor is sound, and a control signal for maintaining a rotation
speed used so far is output to the inverter 4. When the measurement value of the
sensor 5 falls outside the soundness range, a signal for performing feedback control of
the rotation speed of the electric motor 3 is output to the inverter 4 so that the
10 measurement value of the sensor 5 falls within the soundness range.
[0021]
To obtain a signal for performing feedback control of the rotation speed of the
electric motor 3 so that the measurement value of the sensor 5 falls within the
soundness range because the measurement value of the sensor 5 is outside the
15 soundness range, the rotation speed of the electric motor 3 may be changed
temporarily to check a subsequent measurement value of the sensor 5 and determine a
control method.
[0022]
Specifically, the signal processing unit 7 transmits a control signal for increasing
20 the rotation speed by a certain rotation speed (for example, a predetermined rotation
speed per minute) to the inverter 4. If a measurement value of the sensor 5 after a
predetermined time period (specifically, one minute) is changing to a value within the
soundness range, the control signal for increasing the rotation speed of the electric
motor 3 is continuously output to the inverter 4. On the other hand, if a measurement
25 value of the sensor 5 after the predetermined time period changes to a value further
outside the soundness range, a control signal for reducing the rotation speed of the
electric motor 3 is output to the inverter 4. After this operation is repeated, at a point in
time when a measurement value of the sensor 5 after control falls within the soundness
range, a control signal for changing the rotation speed of the electric motor 3 back to an
30 original rotation speed is output to the inverter 4, and the rotation speed is maintained.
9
[0023]
Fig. 2 is a flowchart of a control method according to Embodiment 1. Referring
to Fig. 2, a method in which the rotation speed of the electric motor 3 is controlled by
the inverter 4 through six steps will be described.
5 [0024]
Step S0: In an initial control step S0, an apparatus, such as a sensor airconditioning apparatus or refrigeration apparatus, including the refrigerant compressor 6
is activated. The electric motor 3 of the refrigerant compressor 6 rotates, the rotating
shaft 1 and the rotor 3b fixed to the rotating shaft 1 also rotate, and suction,
10 compression, and discharge are performed by the compressor 6.
[0025]
Step S1: In a first control step S1, the sensor 5 starts measuring a state of the
sliding bearing 2 with suction, compression and discharge being performed by the
compressor 6. Specifically, the displacement sensor 5 measures a clearance between
15 the sliding bearing 2 and the rotating shaft 1. A value measured by the sensor 5 varies
depending on a physical quantity measured by the sensor. A physical quantity to be
measured values depending on the type of the sensor 5.
[0026]
Step S2: In a second control step S2, a measurement value measured by the
20 sensor 5 is compared with a preset threshold value that is a criterion of soundness of
the measurement value to determine whether or not the measurement value is within a
soundness range. For example, the case will be described where an upper limit
threshold value of a bearing clearance judged to be sound is preset. When the
measurement value measured by the sensor 5 or a value obtained by converting the
25 measurement value into the magnitude of the bearing clearance is less than the
threshold value, the flow proceeds to step S3.
[0027]
Step S3: In a third control step S3, it is checked whether or not there is a stop
command to stop the refrigerant compressor 6, air-conditioning apparatus, or
30 refrigeration apparatus. When there is the stop command, the refrigerant compressor
10
6, air-conditioning apparatus, or refrigeration apparatus is stopped. When there is no
stop command, the flow proceeds to step S4.
[0028]
Step S4: In a fourth control step S4, the signal processing unit 7 outputs, to the
5 inverter 4, a control signal for the rotation speed of the electric motor 3 preset in
accordance with operation settings of the refrigerant compressor 6, air-conditioning
apparatus, or refrigeration apparatus. The flow proceeds to step S6 to be described
and then returns to step S1. The above control from steps S1 to S6 and back to S1 is
basic operation for the case where the state of the refrigerant compressor 6 is sound.
10 [0029]
Next, in step S2, the case will be described where the measurement value of the
sensor 5 or the magnitude of the bearing clearance is not less than the threshold value.
When the measurement value of the sensor 5 or the magnitude of the bearing
clearance is not less than the threshold value, the flow proceeds to step S5.
15 [0030]
Step S5: In a fifth control step S5, the signal processing unit 7 generates a control
signal (command) for changing the rotation speed of the electric motor 3 and outputs
the control signal to the inverter 4. The inverter having received this control signal
controls the electric motor 3 to change the rotation speed of the electric motor 3, and
20 the flow proceeds to step S6.
[0031]
Step S6: In a sixth control step S6, the signal processing unit 7 outputs a control
signal (command) for maintaining the rotation speed of the electric motor 3 to the
inverter 4. The inverter 4 having received this control signal controls the electric motor
25 3 to maintain the rotation speed of the electric motor 3, and the flow returns to step S1.
[0032]
The flow returns from step S6 to step S1 and proceeds to step S2. At this time,
in the second control step S2, a measurement value measured by the sensor 5 is
compared with the preset threshold value that is a criterion of soundness of the
30 measurement value to determine whether or not the measurement value is within the
11
soundness range. As a result of the determination, when the sensor measurement
value measured by the sensor 5 or a value obtained by converting the measurement
value into the magnitude of the bearing clearance is within the soundness range, that is,
is less than the threshold value, the flow proceeds to step S6 through step S3, and
5 consequently control is performed to maintain the rotation speed of the electric motor 3.
On the other hand, as a result of the determination, when the sensor measurement
value measured by the sensor 5 or a value obtained by converting the measurement
value into the magnitude of the bearing clearance remains outside the soundness
range, that is, remains not less than the threshold value, steps S1, S2, S5, S6, and S1
10 are sequentially performed until the bearing clearance falls within the soundness range,
that is, reaches a value less than the threshold value.
[0033]
In the above description, although the preset threshold value in step S2 is an
upper limit threshold value of the bearing clearance, the case where the preset
15 threshold value is a lower limit threshold value of the bearing clearance is as follows.
In step S2, when the bearing clearance is above the threshold value, the flow proceeds
to step S3. When the bearing clearance is not more than the threshold value, the flow
proceeds to step S5. The above-described steps are continued until a stop command
to stop the refrigerant compressor 6, air-conditioning apparatus, or refrigeration
20 apparatus is given.
[0034]
In the above description, although the cases where the respective threshold
values are an upper limit threshold value and a lower limit threshold value of the bearing
clearance have been separately described, the threshold value may be composed of an
25 upper limit threshold value and a lower limit threshold value so that a range between the
upper limit threshold value and the lower limit threshold value is defined as a soundness
range. In this case, when the signal processing unit 7 determines in step S2 whether
or not the measurement value measured by the sensor 5 or the magnitude of the
bearing clearance is within the soundness range, if the measurement value measured
30 by the sensor 5 or the magnitude of the bearing clearance is above the lower limit
12
threshold value and is less than the upper limit threshold value, the signal processing
unit 7 determines that the measurement value measured by the sensor 5 or the
magnitude of the bearing clearance is within the soundness range. Otherwise, it is
determined that the measurement value measured by the sensor 5 or the magnitude of
5 the bearing clearance is outside the soundness range.
[0035]
Furthermore, when it is determined that the measurement value or the magnitude
of the bearing clearance is outside the soundness range, a control signal for changing
the rotation speed of the electric motor 3 generated by the signal processing unit 7 in
10 step S5 typically differs according to cases where the measurement value or the
magnitude of the bearing clearance is not more than the lower limit threshold value and
where the measurement value or the magnitude of the bearing clearance is not less
than the upper limit threshold value. A control signal for increasing the rotation speed
of the electric motor 3 is the inverse of a control signal for reducing the rotation speed of
15 the electric motor 3.
[0036]
Fig. 3 is a flowchart of another control method according to Embodiment 1.
Incidentally, in Fig. 3, A to E at respective ends are names for distinguishing between
situations of the control steps. When steps S0 preceding the respective ends are the
20 same, processes performed in the respective steps S0 are similar to each other.
[0037]
When it is determined that the state of the refrigerant compressor 6, airconditioning apparatus, or refrigeration apparatus is within the soundness range, steps
S1A, S2A, S3, S4A, and S1A that are the same in details as the above-described
25 control steps S1, S2, S3, S4, and S1 are sequentially performed.
[0038]
Next, the case where the flow proceeds to control that is a process of changing
the rotation speed of the electric motor 3, that is, the case where it is determined in the
above-described step S2 that the measurement value of the sensor 5 or the magnitude
30 of the bearing clearance is outside the soundness range will be described. First, the
13
case will be described where the threshold value is an upper limit threshold value of the
bearing clearance.
[0039]
Step S1A: This step corresponds to the above-described step S1. As described
5 above, the displacement sensor 5 measures a clearance between the sliding bearing 2
and the rotating shaft 1 with suction, compression, and discharge being performed by
the compressor 6.
[0040]
Step S2A: This step corresponds to the above-described step S2. When the
10 measurement value measured by the sensor 5 or the magnitude of the bearing
clearance is not less than the threshold value, it is determined that the measurement
value or the magnitude of the bearing clearance is outside the soundness range, and
the flow proceeds to step S5-1 in which the signal processing unit 7 first generates a
control signal for "increasing" the electric motor rotation speed and outputs the control
15 signal to the inverter 4, and then proceeds to step S1B. When the measurement value
measured by the sensor 5 or the magnitude of the bearing clearance is less than the
threshold value, it is determined that the measurement value or the magnitude of the
bearing clearance is within the soundness range, and the flow proceeds to step S3.
[0041]
20 Step S5-1: The signal processing unit 7 generates a control signal for
"increasing" the rotation speed of the electric motor 3 and outputs the control signal to
the inverter 4 to "increase" the rotation speed of the electric motor 3.
[0042]
Step S1B: The process of the above-described step S1 is performed again. In
25 particular, the sensor 5 measures a state of the sliding bearing, and the flow proceeds
to step S7A.
[0043]
Step S7A: In step S7A, a sensor measurement value or magnitude of a bearing
clearance most recently measured is compared with the sensor measurement value or
30 magnitude of the bearing clearance previously measured. Here, the case will be
14
described where the signal processing unit 7 determines whether the latest bearing
clearance has increased with respect to the previous bearing clearance.
1) When the latest bearing clearance has decreased from the previous bearing
clearance, it is found, as a result of the change, that the state has changed for the
5 better, and thus the process flow proceeds to step S6B in which the rotation speed of
the electric motor 3 is maintained and then proceeds to step S2A.
2) When the latest bearing clearance increases or does not change from the
previous bearing clearance, it is found, as a result of the change, that the state changes
for the worse or does not change, and thus the process flow proceeds to step S5-2 in
10 which the rotation speed of the electric motor 3 is contrarily "reduced" this time.
[0044]
Step S6B: As in the above-described step S6, the signal processing unit 7
generates a control signal for maintaining the rotation speed of the electric motor 3 and
outputs the control signal to the inverter 4 to maintain the rotation speed of the electric
15 motor 3.
[0045]
Step S5-2: The signal processing unit 7 generates a control signal for "reducing"
the rotation speed of the electric motor 3 and outputs the control signal to the inverter 4
to "reduce" the rotation speed of the electric motor 3. Next, the flow proceeds to step
20 S1C.
[0046]
Step S1C: The process of the above-described step S1 is performed again. In
particular, the sensor 5 measures a state of the sliding bearing, and the flow proceeds
to step S7B.
25 [0047]
Step S7B: In step S7B, a sensor measurement value or magnitude of a bearing
clearance most recently measured is compared with the sensor measurement value or
magnitude of the bearing clearance previously measured.
15
1) When the latest bearing clearance has decreased from the previous bearing
clearance, it is found, as a result of the change, that the state has changed for the
better, and thus the flow proceeds to step S6C.
2) When the latest bearing clearance increases or does not change from the
5 previous bearing clearance, it is found, as a result of the change, that the state changes
for the worse or does not change. In this step, even when the last rotation speed of
the electric motor 3 is "reduced" or "increased", it is found that the state changes for the
worse or does not change. In this case, the flow proceeds to step S6E.
[0048]
10 Step S6C: As in the above-described step S6, the signal processing unit 7
generates a control signal for maintaining the rotation speed of the electric motor 3 and
outputs the control signal to the inverter 4 to maintain the rotation speed of the electric
motor 3. The flow proceeds to step 2B.
[0049]
15 Step S2B: Since it is found, as a result of a "reduction" in the rotation speed of
the electric motor 3, in step S7B that the state has changed for the better, when a
measurement value or magnitude of a bearing clearance measured again by the sensor
5 is not less than the threshold value, it is determined that the measurement value or
magnitude of the bearing clearance is outside the soundness range, and the flow
20 proceeds to step S5-2 in which the signal processing unit 7 generates a control signal
for "reducing" the electric motor rotation speed and outputs the control signal to the
inverter 4. When the measurement value or magnitude of the bearing clearance is less
than the threshold value, the measurement value or magnitude of the bearing clearance
is within the soundness range, and the flow proceeds to step S6D in which the rotation
25 speed of the electric motor 3 is maintained.
[0050]
Step S6D: As in the above-described step S6, the signal processing unit 7
generates a control signal for maintaining the rotation speed of the electric motor 3 and
outputs the control signal to the inverter 4 to maintain the rotation speed of the electric
30 motor 3, and then the flow proceeds to step S1A. This step is a process performed
16
when it is determined that the measurement value or magnitude of the bearing
clearance is within the soundness range.
[0051]
Step S6E: As in the above-described step S6, the signal processing unit 7
5 generates a control signal for maintaining the rotation speed of the electric motor 3 and
outputs the control signal to the inverter 4 to maintain the rotation speed of the electric
motor 3, and then the flow proceeds to step S1A so that a flow sequence is performed.
Through this process flow, a search is made for a rotation speed of the electric motor 3
at which the bearing clearance reaches a value less than the threshold value.
10 [0052]
S3 illustrated in Fig. 3 indicates that, when the measurement value measured by
the sensor 5 or the magnitude of the bearing clearance is less than the threshold value
in step S2A, it is determined that the measurement value or the magnitude of the
bearing clearance is within the soundness range, and that the process proceeds to step
15 S3. In step S3, as in the above-described step S3, it is checked whether or not there is
a stop command to stop the refrigerant compressor 6, air-conditioning apparatus, or
refrigeration apparatus. When there is the stop command, the refrigerant compressor
6, air-conditioning apparatus, or refrigeration apparatus is stopped. When there is no
stop command, the process flow proceeds to steps S4/S6A. S4/S6A illustrated in Fig.
20 3 mean that processes similar to those of the above-described steps S4 and S6 are to
be performed. In other words, in step S4, the signal processing unit 7 outputs, to the
inverter 4, a control signal for the rotation speed of the electric motor 3 preset in
accordance with operation settings of the refrigerant compressor 6, air-conditioning
apparatus, or refrigeration apparatus, and, in step S6A, the signal processing unit 7
25 outputs a control signal (command) for maintaining the rotation speed of the electric
motor 3 to the inverter 4.
[0053]
Incidentally, in the above-described control flow, either the electric motor rotation
speed increase command step S5-1 in which a command to increase the rotation speed
30 of the electric motor 3 is given or the electric motor rotation speed reduction command
17
step S5-2 in which a command to reduce the rotation speed of the electric motor 3 is
given can be performed first. In other words, in the above description, although the
electric motor rotation speed increase command step S5-1 is performed first following
step S2A, the electric motor rotation speed reduction command step S5-2 may be
5 performed first. Furthermore, if the order in which the steps are performed is reversed
in this way, steps to be performed following both of the steps proceed in the same
manner as above.
[0054]
Furthermore, it is also conceivable that both an upper limit and a lower limit are
10 set as a threshold value for the bearing clearance. In this case, the rotation speed of
the electric motor 3 only has to be controlled so that a measured bearing clearance falls
within a soundness range between the upper and lower limits of the threshold value in
steps S2A and S2B.
[0055]
15 Furthermore, in steps S7A and S7B, it may be determined whether a latest
bearing clearance has decreased with respect to the previous physical quantity
(previous bearing clearance). In the case where it is determined whether a latest
bearing clearance has decreased with respect to the previous physical quantity, steps to
which the flow proceeds in accordance with results of the determination only have to be
20 changed in accordance with the fact that the threshold value is an upper limit or lower
limit of the bearing clearance. For example, when the threshold value is the lower limit,
it is determined in step S7A whether a physical quantity has decreased. When the
physical quantity has decreased, the flow proceeds to step 5-2, and the signal
processing unit 7 generates a control signal for "reducing" the rotation speed of the
25 electric motor 3 and outputs the control signal to the inverter 4 to "reduce" the rotation
speed of the electric motor 3. On the other hand, when the physical quantity has not
decreased, the process flow proceeds to step S6B, and the signal processing unit 7
generates a control signal for maintaining the rotation speed of the electric motor 3 and
outputs the control signal to the inverter 4 to maintain the rotation speed of the electric
30 motor 3. Furthermore, it is determined in step S7B whether a physical quantity has
18
decreased. When the physical quantity decreases or does not change, the flow
proceeds to step S6E. When the physical quantity has increased, the flow proceeds to
step S6C.
[0056]
5 In other words, when the threshold value is an upper limit threshold value of the
bearing clearance and a measured bearing clearance is not less than the threshold
value, the rotation speed of the electric motor 3 only has to be controlled so that a latest
bearing clearance decreases and reaches a value less than the threshold value in steps
S7A and S7B. On the other hand, when the threshold value is a lower limit threshold
10 value of the bearing clearance and the bearing clearance is not more than the threshold
value, the rotation speed of the electric motor 3 only has to be controlled so that a latest
bearing clearance does not decrease any further and exceeds the threshold value in
steps S7A and S7B.
[0057]
15 Incidentally, the signal processing unit 7 specifies a target rotation speed of the
electric motor 3, and the inverter 4 performs control to achieve this target rotation
speed. With respect to control of the rotation speed of the electric motor 3 performed
by the inverter 4, control methods based on any control theory in addition to classical
control theory in which, for example, an object to be controlled is regarded as an input20 output system expressed in terms of a transfer function and the desired behavior
thereof is achieved, and fuzzy control theory in which control based on a control model
using fuzzy sets is performed may be used.
[0058]
Next, in the above-described process, when it is determined that a measurement
25 value measured or magnitude of a bearing clearance is outside the soundness range,
the signal processing unit 7 changes the rotation speed of the electric motor 3.
Specifically, it will be described, when it is determined in steps S5, S5-1, and S5-2 that a
measurement value or magnitude of a bearing clearance is outside the soundness
range, how to determine the amount of change in rotation speed by which the rotation
30 speed of the electric motor 3 is to be changed.
19
[0059]
Here, the amount of change in electric motor rotation speed is defined as N to
provide a description. A unit of rotation speed, such as N, is revolutions per unit time,
for example, revolutions per minute [RPM]. How to most readily give the amount of
5 change N in rotation speed of the electric motor 3 is to add or subtract a preset value
to or from the current rotation speed of the electric motor 3. That is, this is as
expressed by the following equation 1.
[0060]
N = N0 + a·N ···· (1)
10 Note the following.
N: electric motor rotation speed after the change, N0: electric motor rotation
speed before the change,
a: coefficient in a range of -1  a  1, N: any constant value that can be set
[0061]
15 Here, in the above-described steps (steps S5, S5-1, and S5-2), when the
coefficient a in equation 1 is successively changed, the rotation speed N of the electric
motor 3 can be discretely changed.
[0062]
Furthermore, N may be given in accordance with the electric motor rotation
20 speed N0 before the change as expressed by the following equation 2.
[0063]
N = a·N0 ···· (2)
[0064]
As expressed by equation 2 described above, N is obtained by multiplying the
25 rotation speed N0 of the electric motor 3 before the change by the coefficient a, and
thus, even when N is not preset, the electric motor rotation speed can be changed as
expressed by the following equation 3.
[0065]
N = N0 + N = (1 + a)·N0 ···· (3)
30 [0066]
20
Here, the coefficient a is first given an appropriate initial value (for example, 0.1),
and the value of the coefficient a is changed in steps S5-1 and S5-2 in accordance with
results of determinations made in steps S7A and S7B. If the bearing clearance is likely
to fall within the soundness range, for example, by increasing the rotation speed, the
5 coefficient a can be increased, for example, from 0.1 to 0.2.
[0067]
The above-described method of changing a rotation speed of the electric motor 3
is an example, and Embodiment 1 can be applied regardless of the method of changing
an electric motor rotation speed. Furthermore, for a rotation speed of the electric
10 motor 3 specified by the signal processing unit 7 in such a way, as an electric motor
rotation speed control method implemented by the inverter 4, any control method can
be applied in the present disclosure in addition to Pulse Width Modulation (PWM) or
Pulse Amplitude Modulation (PAM).
[0068]
15 Next, a threshold value (hereinafter, also referred to as Hlim) of a bearing
clearance will be described. When the displacement sensor 5 is installed at the sliding
bearing 2, a bearing clearance of the sliding bearing 2 (a distance between the rotating
shaft 1 and the inner surface of the sliding bearing 2) can be measured. When the
displacement sensor 5 measures a bearing clearance, a quantitative evaluation can be
20 performed, for example, on the contact between the rotating shaft 1 and the bearing
(sliding bearing 2), or a margin provided before the contact is achieved even if there is
no contact.
[0069]
Fig. 4 is a schematic diagram illustrating a cross-section perpendicular to a
25 central axis of rotation of the rotating shaft 1 in the sliding bearing 2. Fig. 4 illustrates a
state in which the rotating shaft 1 is eccentric. As illustrated in Fig. 4, when a load
(arrow in Fig. 4) acts on the rotating shaft 1, the rotating shaft 1 is made eccentric in a
load direction L1 (arrow in Fig. 4) with respect to a bearing center C2 of the sliding
bearing 2. At this time, for example, when the displacement sensor 5 is installed at a
30 first quadrant and a second quadrant (portions of the sliding bearing 2 on an opposite
21
side to the load direction L1) with respect to a bearing center line, a measured bearing
clearance increases in accordance with the degree of eccentricity of the rotating shaft 1.
In this case, the electric motor rotation speed only has to be controlled so that the
bearing clearance decreases.
5 [0070]
On the other hand, when the displacement sensor 5 is installed at a third
quadrant and a fourth quadrant (portions of the sliding bearing 2 on a side facing the
load direction L1) with respect to the bearing center line, the bearing clearance
decreases, and thus the electric motor rotation speed only has to be controlled so that
10 the bearing clearance increases.
[0071]
Furthermore, unlike the above description, it is conceivable that some bearing
lubrication conditions make the load direction L1 and the direction of eccentricity
opposite to each other. In this case, as the threshold value Hlim for the bearing
15 clearance described in Embodiment 1, both an upper limit threshold value and a lower
limit threshold value are set, and the electric motor rotation speed only has to be
controlled so that the bearing clearance falls within a range between the upper limit
threshold value and the lower limit threshold value. The range between the upper limit
threshold value and the lower limit threshold value of the bearing clearance is the
20 above-described soundness range.
[0072]
Fig. 5 is a cross-sectional view of the refrigerant compressor in which the
displacement sensor 5 is installed at a rotating shaft portion fitted into the sliding
bearing 2. Of the rotating shaft 1, in a portion inserted into the sliding bearing 2, the
25 displacement sensor is embedded outward in a radial direction of the rotating shaft 1.
When the displacement sensor 5 is installed at the rotating shaft portion fitted into the
sliding bearing 2 as illustrated in Fig. 5, a bearing clearance of the sliding bearing 2 can
be measured over the whole circumference from a rotating shaft 1 side. In other
words, for a minimum value and a maximum value of bearing clearances measured
30 during one revolution of the rotating shaft 1, a lower limit threshold value and an upper
22
limit threshold value are respectively set, and a rotation speed of the electric motor 3
only has to be controlled so that the minimum value falls below the lower limit threshold
value or the maximum value does not exceed the upper limit threshold value. In this
case as well, a range between the upper limit threshold value and the lower limit
5 threshold value within which the minimum value and the maximum value of the bearing
clearances measured fall is the above-described soundness range.
[0073]
How to set a value of the threshold value Hlim of the bearing clearance will be
described. For example, any value, or a percentage relative to a difference between a
10 rotating shaft outside diameter and a bearing inside diameter can be set in advance. A
value of the threshold value Hlim of the bearing clearance may be set in accordance with
the magnitude of a bearing diametral clearance of the sliding bearing 2. For example,
a setting method based on the following equation 4 is conceivable.
[0074]
15 Hlim = b·C ···· (4)
Note the following. b: coefficient in a range of 0 < b < 1, C: bearing diametral
clearance = bearing inside diameter - shaft outside diameter
[0075]
Here, the bearing diametral clearance C may be a bearing radial clearance. In
20 this case, the range of the coefficient b is 0 < b < 2. Furthermore, surface roughness
either of the outside diameter of the rotating shaft 1 or of the inside of the sliding bearing
2 may be used in place of the bearing diametral clearance. Alternatively, the sum of
the surface roughness of the outside diameter of the rotating shaft 1 and the surface
roughness of the inside of the sliding bearing 2, or the square-root of the sum of
25 squares of the surface roughness of the outside diameter of the rotating shaft 1 and the
surface roughness of the inside of the sliding bearing 2 may be used. Each of values
obtained by multiplying both these values as alternatives to the bearing diametral
clearance by the coefficient b can be set as a value of the threshold value Hlim of the
bearing clearance. Note that, when surface roughness is used, the coefficient b only
30 has to be a value not less than 0 and does not have to be not more than 1.
23
[0076]
Here, a change in the state of the sliding bearing 2, such as a bearing clearance,
based on a change in the rotation speed of the electric motor 3 will be described.
When the electric motor 3 rotates, the rotating shaft 1 and the rolling pistons rotate as
5 one around the central axis of rotation of the rotating shaft 1, the compression
chambers between cylinders and the rolling pistons are sequentially deformed, and
steps of suctioning, compressing, and discharging the medium inside each compression
chamber are repeated. At this time, the sliding bearings 2 provided on both sides in
axial directions of the rolling pistons and supporting the rotating shaft 1 are subjected to
10 an eccentric load from the rotating shaft 1 by each step, that is, positions of the rolling
pistons around the rotating shaft. Here, when the rotation speed of the electric motor 3
changes, the magnitude of an oil film pressure generated in a bearing clearance
changes. Thus, an eccentric position of the rotating shaft changes, the distribution of
the bearing clearance necessarily changes, and the state of each sliding bearing 2
15 changes.
[0077]
In Embodiment 1, a bearing clearance representing the state of the refrigerant
compressor 6 is measured by the displacement sensor 5, a bearing clearance threshold
value with a margin for the contact or seizure between the rotating shaft 1 and the
20 sliding bearing 2 is set, and a rotation speed of the electric motor 3 is controlled by the
inverter 4 in accordance with the measured bearing clearance and the set threshold
value. Thus, from a region where a load on the compressor is large to a region where
a load on the compressor is small, the contact or seizure between the rotating shaft 1
and the sliding bearing 2 can be avoided.
25 [0078]
Furthermore, by using the sensor 5 that is provided at the sliding bearing 2 or the
rotating shaft 1 into which the sliding bearing 2 is fitted and that outputs a measured
measurement value as an output signal, and a control unit that performs an arithmetic
operation on the output signal output from the sensor 5 to obtain a rotation speed at
30 which the electric motor is to rotate and that transmits the rotation speed as a control
24
signal to the inverter 4 to control a rotation speed of the electric motor 3, a failure in the
bearing 2 is avoided in a wide range of operating conditions. Furthermore, the contact
between the rotating shaft 1 and the bearing 2 of the compressor 6, and a seizure and
abnormal wear involved in this contact can be avoided without stopping the operation of
5 the compressor 6.
[0079]
(Case Where Vibration Sensor Is Used)
Next, an example will be described where a vibration sensor is used as the
sensor 5 provided at the sliding bearing 2 or a portion of the rotating shaft 1 into which
10 the sliding bearing 2 is fitted. The vibration sensor that is the sensor 5 measures
vibration of the sliding bearing 2 or the sliding bearing 2. Incidentally, the vibration
sensor here is not limited to an acceleration sensor, and any type of sensor can be used
regardless of measurement principles, or a contact or non-contact method.
Furthermore, in the case where the vibration sensor is used as the sensor 5, the
15 vibration sensor may be provided not only at the above-described sliding bearing 2 or
the portion of the rotating shaft 1 into which the sliding bearing 2 is fitted, but also at the
compressor 6 for which vibration isolation from the sliding bearing 2 or the portion of the
rotating shaft 1 into which the sliding bearing 2 is fitted is not provided, or at an
enclosure that houses this.
20 [0080]
When the rotating shaft 1 and the sliding bearing 2 are operating with them being
separated by an oil film and being not in contact with each other, vibration caused by
rotation of the rotating shaft 1 attenuates due to the viscosity of lubricating oil. For this
reason, the level of vibration that propagates to the bearing 2 is smaller than that in the
25 case where the rotating shaft 1 and the bearing 2 are in contact with each other. Thus,
when the sensor 5 that is the vibration sensor measures a vibration level (magnitude of
vibration amplitude) or acceleration of the rotating shaft 1 or the bearing 2, the contact
between the rotating shaft 1 and the bearing 2 can be detected. Furthermore, when
the contact is detected, a rotation speed of the electric motor 3 is changed, and thus a
30 seizure can be avoided.
25
[0081]
Next, operation will be described. A basic control method is similar to that for
the above-described displacement sensor. With respect to a threshold value of a
vibration level or acceleration, however, when the contact occurs as described above,
5 vibration of the shaft or the bearing increases, and thus it is desirable to set an upper
limit value. As the threshold value of the vibration level or acceleration, any upper limit
value alim may be set. In this case, the above-described soundness range is a range in
which the vibration level or acceleration is not more than the upper limit value alim.
[0082]
10 The signal processing unit 7 uses a range of not more than the upper limit value
alim as the soundness range and obtains a signal for performing feedback control of the
rotation speed of the electric motor 3 so that a measurement value of the sensor 5 that
is the vibration sensor falls within the soundness range.
[0083]
15 Specifically, when a measurement value of the vibration sensor exceeds the
upper limit value alim, the rotation speed of the electric motor 3 is changed, and control
is changed in accordance with whether or not a measurement value measured by the
vibration sensor that is the sensor 5 after the rotation speed has been changed has
approached the soundness range. Here, a change made to the rotation speed refers
20 to an increase or reduction in the rotation speed.
[0084]
For example, when the measurement value of the vibration sensor is likely to fall
outside the soundness range, that is, when the measurement value of the vibration
sensor is increased further, a change is made in a direction opposite to the direction of
25 the last change made to the rotation speed of the electric motor 3, and then a
measurement value of the vibration sensor is checked. When the measurement value
of the vibration sensor is reduced, the state is changing for the better, and thus the
rotation speed of the electric motor 3 is maintained. Alternatively, when the
measurement value of the vibration sensor is not less than a predetermined value
30 greater than the upper limit value alim, a further change is made to the rotation speed of
26
the electric motor 3 in the direction of the last change so that a further improvement is
achieved, that is, so that vibration is reduced, thus enabling the vibration of the bearing
2 to converge to a value within the soundness range early.
[0085]
5 Incidentally, even if the rotation speed of the above-described electric motor 3 is
changed in the direction opposite to the direction of the last change, when the
measurement value of the vibration sensor is not reduced, the rotation speed of the
electric motor 3 is changed again by reducing the amount of change in rotation speed,
and such an operation is repeated to search for a rotation speed at which the
10 measurement value measured by the vibration sensor after the rotation speed has been
changed is reduced. When the rotation speed at which the measurement value of the
vibration sensor is reduced can be found, the rotation speed is maintained, or a search
is made for a rotation speed at which the measurement value is further reduced, and
the electric motor 3 is controlled to achieve a rotation speed at which the state changes
15 for the better. When such control is performed, a departure from a situation in which
abnormal vibration occurs is achieved, and a seizure in the sliding bearing 2 is avoided
without stopping the operation.
[0086]
Here, the fact that, when vibration of the bearing increases, the vibration of the
20 bearing is changed by changing the rotation speed of the electric motor 3 will be
described. In the case where the rotating shaft and the bearing come in direct contact
with each other, acceleration caused by friction occurs in comparison with the case
where the rotating shaft and the bearing are not in contact with each other. As
described above, when the rotation speed of the electric motor 3 is changed to achieve
25 a non-contact state, vibration acceleration is reduced. Furthermore, when a bearing
clearance is very small even in a non-contact state, the magnitude of an oil film
pressure in the bearing clearance is proportional to the inverse of the cube of the
bearing clearance, a very high pressure is therefore generated, an eccentric position of
the rotating shaft varies, and thus vibration acceleration based on the amount of
30 variation is generated. Hence, the vibration of the bearing can be changed by
27
changing the rotation speed of the electric motor 3. The fact that the vibration of the
bearing is caused to fall within the soundness range by changing the rotation speed of
the electric motor 3 corresponds to the fact that the above-described bearing clearance
is caused to fall within the soundness range.
5 [0087]
In Embodiment 1, a vibration level or acceleration of the rotating shaft 1 or the
bearing 2 generated when the rotating shaft 1 and the bearing 2 come in contact with
each other or when a distance between the rotating shaft 1 and the bearing 2 decreases
is measured by the vibration sensor, and the rotation speed of the electric motor 3 is
10 controlled by the inverter 4 so that the measured vibration level or acceleration falls
below the threshold value of the vibration level or acceleration. Thus, a seizure
between the rotating shaft 1 and the sliding bearing 2 can be avoided.
[0088]
(Case Where Temperature Sensor Is Used)
15 Next, an example will be described where a temperature sensor that measures a
bearing temperature is used as the sensor 5 provided at the sliding bearing 2 or a
portion of the rotating shaft 1 into which the sliding bearing 2 is fitted. The temperature
sensor that is the sensor 5 measures a temperature of the sliding bearing 2 or the
sliding bearing 2. Incidentally, the temperature sensor here is not limited to a particular
20 sensor, such as a thermocouple, and any type of sensor can be used regardless of
measurement principles, or a contact or non-contact method.
[0089]
In the case where a seizure between the rotating shaft 1 and the sliding bearing 2
occurs, the contact between the rotating shaft 1 and the sliding bearing 2 occurs before
25 the occurrence of the seizure. When the contact occurs, friction occurs at a contact
area, most of energy of friction is consumed as heat energy, and temperatures of the
sliding bearing 2 and a surrounding area connected to the sliding bearing 2 increase.
Hence, contact between the rotating shaft 1 and the sliding bearing 2 is detected by
measuring a temperature inside the refrigerant compressor 6, for example, a bearing
28
temperature, appropriate control is performed by using this detection as a trigger, and
thus a seizure between the rotating shaft 1 and the sliding bearing 2 can be avoided.
[0090]
Next, operation will be described. A basic control method is similar to that for
5 the case where the above-described sensor 5 is a displacement sensor. With respect
to a threshold value for a measurement value of the sensor 5 that is a temperature
sensor, however, a temperature is increased by heat generation caused by the friction
between the rotating shaft 1 and the sliding bearing 2 as described above, and thus it is
desirable to set an upper limit value. As the threshold value of the temperature of the
10 sliding bearing 2, any upper limit value Tlim may be set. As a result, a soundness
range is a range of not more than the upper limit value Tlim.
[0091]
The signal processing unit 7 uses a range of not more than the above-described
upper limit value Tlim as the soundness range and performs feedback control of a
15 rotation speed of the electric motor 3 so that a measurement value of the sensor 5 that
is the temperature sensor falls within the soundness range.
[0092]
Specifically, when a measurement value of the temperature sensor falls outside
the soundness range, that is, exceeds the upper limit value Tlim, the rotation speed of
20 the electric motor 3 is changed, and control is changed in accordance with whether or
not a measurement value measured by the sensor 5 (temperature sensor) after the
rotation speed has been changed has approached the soundness range.
[0093]
Control of the electric motor 3 performed when the sensor 5 is the temperature
25 sensor and the soundness range is the range of not more than the upper limit value
Tlim is basically similar to control performed when the above-described vibration sensor
is used as the sensor 5. In other words, when, in control using the above-described
vibration sensor, the vibration sensor is replaced with the temperature sensor and the
upper limit value alim is replaced with the upper limit value Tlim, the control can be
30 regarded as control using the temperature sensor.
29
[0094]
Here, the fact that, when a temperature of the bearing increases, the temperature
of the bearing is changed by changing the rotation speed of the electric motor 3 will be
described. In the case where the rotating shaft and the bearing come in direct contact
5 with each other, an increase in temperature due to frictional shear between materials
occurs, conduction of heat through a material occurs, and thus temperatures of the
bearing and the rotating shaft increase. As described above, when the rotation speed
of the electric motor 3 is changed to achieve a non-contact state, an increase in
temperature is suppressed by heat diffusion caused by an oil film. Furthermore, when
10 a bearing clearance is very small even in a non-contact state, fluid shear that occurs in
a bearing oil film increases, an oil film temperature increases, and the temperatures of
the bearing and the rotating shaft increase. Hence, the temperature of the bearing can
be changed by changing the rotation speed of the electric motor 3. The fact that the
temperatures of the bearing and the rotating shaft are caused to fall within the
15 soundness range by changing the rotation speed of the electric motor 3 corresponds to
the fact that the above-described bearing clearance is caused to fall within the
soundness range.
[0095]
In Embodiment 1, heat generated by friction involved in the contact between the
20 rotating shaft 1 and the sliding bearing 2 is measured by the temperature sensor
(sensor 5), and the rotation speed of the electric motor 3 is controlled by the inverter 4
so that the temperature measured by the temperature sensor falls below the threshold
value (upper limit value Tlim) of the temperature. Thus, a seizure between the rotating
shaft 1 and the sliding bearing 2 can be avoided.
25 [0096]
(Case Where Pressure Sensor Is Used)
Next, the refrigerant compressor including, as the sensor 5, a pressure sensor
that measures a pressure generated in an oil film in the sliding bearing 2 of the
compressor 6 will be described. The pressure sensor that is the sensor 5 is not limited
30 to a particular sensor, such as a diaphragm pressure sensor, and may be any sensor
30
that can measure a pressure generated in an oil film in the sliding bearing 2 regardless
of measurement principles.
[0097]
In the case where a seizure between the rotating shaft 1 and the sliding bearing 2
5 occurs, the contact between the rotating shaft 1 and the sliding bearing 2 occurs before
the occurrence of the seizure. In general, the magnitude of a pressure generated in an
oil film in a sliding bearing is proportional to the inverse of the cube of a bearing
clearance. For this reason, immediately before the rotating shaft 1 and the inner
surface of the sliding bearing 2 come in contact with each other, an oil film gets thinner,
10 and the inside of the oil film reach a very high pressure state. Hence, when a pressure
generated in an oil film in the bearing of the compressor 6 is measured by using the
pressure sensor, the contact between the rotating shaft 1 and the sliding bearing 2 can
be detected. When a rotation speed of the electric motor 3 is appropriately controlled
by using this detection as a trigger, a seizure between the rotating shaft 1 and the
15 sliding bearing 2 can be avoided.
[0098]
Next, operation will be described. A basic control method is the same as those
in forms 1 and 2. With respect to a threshold value of pressure, however, an oil film
pressure reaches a very high pressure with a contact state being approached as
20 described above, and thus it is desirable to set an upper limit value. As the threshold
value of the pressure measured by the pressure sensor, any upper limit value Plim may
be set. As a result, a soundness range in this case is a range in which a measurement
value of the sensor 5 is the upper limit value Plim.
[0099]
25 The signal processing unit 7 uses a range of not more than the above-described
upper limit value Plim as the soundness range and performs feedback control of the
rotation speed of the electric motor 3 so that a measurement value of the sensor 5 that
is the pressure sensor falls within the soundness range.
[0100]
31
Specifically, when a measurement value of the pressure sensor falls outside the
soundness range, that is, exceeds the upper limit value Plim, the rotation speed of the
electric motor 3 is changed, and control is changed in accordance with whether or not a
measurement value measured by the sensor 5 (pressure sensor) after the rotation
5 speed has been changed has approached the soundness range.
[0101]
Control of the electric motor 3 performed when the sensor 5 is the pressure
sensor and the soundness range is the range of not more than the upper limit value
Plim is basically similar to control performed when the above-described vibration sensor
10 is used as the sensor 5. In other words, when, in control using the above-described
vibration sensor, the vibration sensor is replaced with the pressure sensor and the
upper limit value alim is replaced with the upper limit value Plim, the control can be
regarded as control using the pressure sensor.
[0102]
15 Here, the fact that, when a pressure in the bearing increases, the pressure in the
bearing is changed by changing the rotation speed of the electric motor 3 will be
described. The magnitude of a pressure generated in a bearing oil film is proportional
to the inverse of the cube of a bearing clearance, a very high pressure is therefore
generated, the magnitude of the bearing clearance is changed by a change in the
20 rotation speed of the electric motor 3, and thus a measurement value of the pressure
sensor is also changed. Hence, the pressure in the bearing can be changed by
changing the rotation speed of the electric motor 3. The fact that a measurement value
of an oil film pressure is caused to fall within the soundness range by changing the
rotation speed of the electric motor 3 corresponds to the fact that the above-described
25 bearing clearance is caused to fall within the soundness range.
[0103]
In Embodiment 1, a pressure generated in an oil film between the rotating shaft 1
and the sliding bearing 2 is measured by the pressure sensor, and the rotation speed of
the electric motor 3 is controlled by the inverter 4 so that the pressure measured by the
32
pressure sensor falls below the threshold value (upper limit value Plim) of the pressure.
Thus, a seizure between the rotating shaft 1 and the sliding bearing 2 can be avoided.
[0104]
As described above, a pressure in an oil film measured by the pressure sensor is
5 proportional to the inverse of the cube of a bearing clearance, and thus the pressure
increases suddenly when the bearing clearance decreases. Thus, it can be said that it
is easy to detect an unsound state, good resistance to noise is exhibited, and efficient
control can be performed.
[0105]
10 In the above description, although a rotation speed of the electric motor 3 is
controlled by using one measurement value of each of the respective types of sensors,
the rotation speed of the electric motor 3 may be controlled by using measurement
values of two or more sensors. This is because the inside of the compressor
undergoes high temperature and high pressure in some operating conditions and
15 sometimes acceleration at other sliding elements occurs. Hence, a plurality of sensors
are installed at the bearing, the rotation speed of the electric motor 3 is controlled by
using respective measurement values, and thus states of the bearing and the rotating
shaft can be comprehensively determined to result in an increase in accuracy of
detecting a state of contact between the bearing and the rotating shaft. Furthermore,
20 there are temperature characteristics in some sensors. When the temperature sensor
and another sensor are used in combination, temperature characteristics of the sensor
used can be corrected, and measurements can be made with higher accuracy.
[0106]
Next, operation in the case where the rotation speed of the electric motor 3 is
25 controlled by using measurement values of a plurality of sensors will be described.
The signal processing unit 7 compares measurement values of the respective sensors
with soundness ranges set for the respective sensors. If at least one of sensor
measurement values falls outside a soundness range, the signal processing unit 7
performs control to change the rotation speed of the electric motor 3. First, the rotation
30 speed of the electric motor 3 is controlled so that a sensor measurement value
33
exceeding a soundness range falls within the soundness range. Furthermore, except
for the sensor measurement value that has fallen outside the soundness range first, if
there is a sensor that has fallen outside a soundness range, the rotation speed of the
electric motor 3 is controlled so that the sensor that has fallen outside the soundness
5 range falls within the soundness range. Thus, the operation of controlling the rotation
speed of the electric motor 3 is repeated until all sensor measurement values fall within
the respective soundness ranges.
[0107]
When the above-described configuration is provided, a sensor having a short
10 time constant, for example, a displacement sensor detects a measurement value having
fallen outside a soundness range, and control can be started to cause the measurement
value to fall within the soundness range. Subsequently, when the above-described
control is performed until a measurement value of a sensor having a long time constant,
for example, a temperature sensor falls within a soundness range, a sufficiently sound
15 state can be achieved, and the state of the sliding bearing 2 can be stabilized.
[0108]
Furthermore, in the case where a displacement sensor (vibration sensor,
pressure sensor) having temperature characteristics is used, in combination with a
temperature sensor, temperature correction can be carried out to result in an increase in
20 accuracy of detecting a state of contact between the bearing and the rotating shaft.
Incidentally, in this case, a temperature measurement value is fed back to the signal
processing unit 7, and temperature correction for the displacement sensor or other
sensors is carried out to result in a further increase in accuracy.
[0109]
25 Embodiment 2.
In Embodiment 1, when a sensor measurement value obtained by a sensor
measuring a state of a bearing falls outside a preset soundness range, a rotation speed
of the electric motor is controlled so that the sensor measurement value falls within the
soundness range. However, the above-described control process is subjected to
30 machine learning to obtain a learned model, and the learned model may be used for a
34
sensor measurement value currently measured to estimate a rotation speed at which
the electric motor is to rotate. In this case, a learned model can be obtained by storing,
as association information, a sensor measurement value, a rotation speed at which the
electric motor is to rotate obtained by the signal processing unit for this measurement
5 value, and a sensor measurement value measured after control has been performed to
achieve this rotation speed in association with one another, and by subjecting the stored
association information to machine learning. When such a configuration is provided,
the rotation speed of the electric motor can be controlled, without being controlled in an
exploratory manner, by obtaining, from the learned model obtained from a past control
10 history, an estimated rotation speed that is a rotation speed at which the electric motor
is to rotate and at which a sensor measurement value is caused to fall within the
soundness range.
[0110]
In other words, in Embodiment 2, while the rotation of the compressor is being
15 controlled by using sensor information in Embodiment 1, learning data in which the
sensor information is regarded as a state and control is regarded as an action is
collected, the collected learning data is subjected to machine learning to create a
learned model, and the learned model is stored in a learning model storage unit.
Assuming that control is temporarily obtained by using the learned model, when the
20 probability that a state is improved reaches not less than a predetermined value,
switching may be performed from the above-described control unit so that an operation
signal for performing control using the learned model is transmitted to an apparatus.
[0111]
Hereinafter, a description will be given with an emphasis on an example where a
25 displacement sensor is used as a sensor, but any other sensors that measures
vibration, temperature, and pressure may be used as in Embodiment 1.
[0112]
Fig. 6 illustrates a configuration of the compressor representing Embodiment 2.
In Fig. 6, a cross-sectional view of the refrigerant compressor is illustrated on the left30 hand side, and a block diagram representing a configuration that controls this
35
compressor is illustrated on the right-hand side. Hereinafter, reference signs that are
the same as those in Embodiment 1 denote the same or corresponding elements.
Furthermore, as in Embodiment 1, a single rotary compressor in which one compressor
mechanism is provided may be provided. Alternatively, any compressor, such as a
5 scroll compressor or screw compressor, supported by a bearing may be provided.
[0113]
In Fig. 6, the refrigerant compressor 6 includes the rotating shaft 1, the sliding
bearings 2 that support this, the electric motor 3, and the inverter 4. The electric motor
3 is constituted by the stator 3a and the rotor 3b. The mechanical structure of the
10 refrigerant compressor 6 is similar to that in Embodiment 1.
[0114]
Furthermore, the refrigerant compressor 6 includes the sensor 5 provided at a
sliding bearing 2 or a portion of the rotating shaft 1 into which the sliding bearing 2 is
fitted, and the signal processing unit 7 that performs an arithmetic operation on an
15 output signal output from the sensor 5 to obtain a rotation speed at which the electric
motor 3 is to rotate and that transmits a signal that transmits a control signal to the
inverter 4.
[0115]
For the sensor 5, there is no difference between contact and non-contact
20 methods. The sensor 5 may be a displacement sensor that measures a displacement
of the sliding bearing 2, a relative displacement between the sliding bearing 2 and the
rotating shaft 1, or a change in the relative displacement, a displacement sensor that
measures vibration of the sliding bearing 2, a temperature sensor, or a pressure sensor
that measures a pressure in an oil film in the sliding bearing 2.
25 [0116]
The refrigerant compressor 6 includes a storage unit 8 that stores, as learning
data, information of a physical quantity subjected to conversion by the signal processing
unit 7, or a sensor voltage signal, and a control signal to the inverter that is a result
obtained by determining a controlled variable by using information, or an operation
30 signal to the air-conditioning apparatus or refrigeration apparatus in association with
36
each other, a machine learning unit 9 that subjects the learning data stored in the
storage unit 8 to machine learning and outputs a learned model, a learning model
storage unit 10 that stores the learned model subjected to machine learning, and a
controlled variable calculation unit 11 that uses the learned model to output a control
5 signal to the inverter 4 or an operation signal to the air-conditioning apparatus or
refrigeration apparatus from information of the above-described physical quantity newly
measured, or a sensor voltage signal. Here, an example is given where the storage
unit 8 stores a sensor voltage signal and an operation signal to the air-conditioning
apparatus or refrigeration apparatus in association with each other. Incidentally, the
10 controlled variable calculation unit 11 may be regarded as an estimation unit.
[0117]
Furthermore, in the learning data stored in the storage unit 8, a result obtained by
transmitting a control signal to the inverter 4 that is a result obtained by determining a
controlled variable by using information, a result obtained by transmitting an operation
15 signal to an apparatus, or a changed sensor voltage signal may be associated with the
above.
[0118]
Incidentally, the storage unit 8 may be a memory, a storage disk, or a
semiconductor memory regardless of whether the storage unit 8 is installed into or
20 outside the refrigerant compressor 6. Furthermore, for the storage unit 8, a storage
medium or a storage method is not specified.
[0119]
Furthermore, the refrigerant compressor 6 according to Embodiment 2 includes
the storage unit 8, the machine learning unit 9, and the learning model storage unit 10
25 and may transmit a learned model stored in the learning model storage unit 10 to the
outside, for example, via a network.
[0120]
Furthermore, the refrigerant compressor 6 according to Embodiment 2 may be
configured to read a learned model into the learning model storage unit 10 from the
30 outside and may cause the controlled variable calculation unit 11 to operate using this
37
learned model. In this case, the refrigerant compressor 6 does not have to include the
storage unit 8 and the machine learning unit 9. Furthermore, the refrigerant
compressor 6 may transmit learning data to the outside, for example, via a network and
may cause the machine learning unit 9 provided outside the refrigerant compressor 6 to
5 subject the learning data to machine learning to construct a learned model. In this
case, the refrigerant compressor 6 may read the learned model into the learning model
storage unit 10 from the outside via a network and may cause the controlled variable
calculation unit 11 to operate using the learned model subjected to learning outside the
refrigerant compressor 6.
10 [0121]
The storage unit 8 stores, as input information representing the state of the
refrigerant compressor 6, information of the sensor provided at the sliding bearing 2 of
the compressor or a rotating portion into which the sliding bearing 2 is fitted. This
sensor 5 may be a displacement sensor that measures a displacement of the rotating
15 shaft 1, and the input information may be information corresponding to a displacement
of the rotating shaft 1 in the sliding bearing 2. Furthermore, information stored in the
storage unit 8 may be, as input information representing the state of the compressor,
information obtained by measuring a bearing clearance of the sliding bearing 2 from the
above-described displacement. Alternatively, the sensor 5 may be a vibration sensor,
20 a temperature sensor, or a pressure sensor that measures an oil film pressure in the
sliding bearing.
[0122]
Furthermore, the storage unit 8 stores, as input information representing an
action, information of a physical quantity subjected to conversion by the signal
25 processing unit 7, and a control signal to the inverter 4 that is a result obtained by
determining a controlled variable by using this information, or an operation signal to the
air-conditioning apparatus or refrigeration apparatus. Furthermore, at this time, the
input information representing a state and the input information representing an action
are stored as learning data in association with each other.
30 [0123]
38
Furthermore, the storage unit 8 stores input information representing a state in
which the state has been changed as a result of executing an action. These may be
stored as time-series information.
[0124]
5 Next, the machine learning unit 9 uses, as an input, a data set created based on
input information representing a state and input information representing an action
stored in the storage unit 8 to learn a learning model that is to act as an output.
Machine learning performed by the machine learning unit 9 may be reinforcement
learning using a value function. In this case, when a measurement value of the sensor
10 5 obtained by controlling the electric motor 3 at a rotation speed output by the signal
processing unit 7 changes from outside the soundness range to within the soundness
range, the machine learning unit 9 may construct a learned model by giving a reward to
the value function. Furthermore, as a learning algorithm used by the machine learning
unit 9, any learning algorithm may be used. As an example, a case where
15 reinforcement learning is used will be described below.
[0125]
In reinforcement learning, an agent (action agent) in a certain environment
observes a current state and determines an action to be taken. When the agent
selects an action, the agent obtains a reward from the environment and learns a policy
20 in which the most rewards are obtained through a series of actions.
[0126]
As typical methods of reinforcement learning performed by the machine learning
unit 9, there are Q-learning and TD learning. For example, in a case of the Q-learning,
a typical update formula (action value table) of an action-value function Q (s, a) is
25 expressed as follows.
[0127]
Q(st, at)  Q(st, at) + (rt+1 + maxQ(st+1, a) - Q(st, at)) ··· (5)
[0128]
In formula 5, st represents an environment at a time t, and at represents an action
30 at the time t. The environment is changed to st+1 by the action at. A reward given by
39
a change in the environment is represented by rt+1. Furthermore,  represents a
discount factor, and  represents a learning coefficient. Incidentally,  is defined by 0 <
  1, and  is defined by 0 <   1. When the Q-learning is used, learning content that
is an output is the action at.
5 [0129]
Here, in the machine learning unit 9, st represents input information representing
a state, at represents input information representing an action, and st+1 represents a
state changed by the action at. A reward given when st is changed to st+1 is rt+1.
[0130]
10 More specifically, st is information of the sensor provided at the sliding bearing of
the compressor or a rotating portion into which the sliding bearing is fitted.
Furthermore, the action at may be information of a physical quantity subjected to
conversion by the signal processing unit, and a control signal to the inverter 4 that is a
result obtained by determining a controlled variable by using information, an operation
15 signal to the air-conditioning apparatus or refrigeration apparatus, or information
representing a rotation speed of the compressor.
[0131]
In the update formula expressed by formula 5, in a case where an action value of
an optimal action a at a time t+1 is greater than an action value Q of an action a
20 executed at the time t, the action value Q is increased, and, in an opposite case, the
action value Q is reduced. In other words, the action-value function Q (s, a) is updated
so that the action value Q of the action a at the time t approaches a best action value at
the time t+1. As a result, an optimal action value in a certain environment is
propagated to an action value in a previous environment.
25 [0132]
The machine learning unit 9 further includes a reward calculation unit and a
function update unit.
[0133]
The reward calculation unit calculates a reward by using a state variable. The
30 reward calculation unit calculates a reward r by using a reference reward. For
40
example, in a case of a reference for reward increase, the reward r is increased (for
example, a reward of "1" is given). On the other hand, in a case of a reference for
reward reduction, the reward r is reduced (for example, "-1" is given).
[0134]
5 For example, assume that a state is a bearing clearance between the bearing of
the bearing 2 and the rotating shaft 1. When the bearing clearance decreases, a
reward is large, and, when the bearing clearance increases, the reward is small.
Furthermore, when the bearing clearance decreases with respect to the abovedescribed threshold value, the reward increases.
10 [0135]
Furthermore, assume that the sensor 5 is a temperature sensor and that a state
is a temperature of the bearing 2. When a bearing temperature decreases, a reward is
large, and, when the bearing temperature increases, the reward is small. Furthermore,
when the bearing temperature reaches not more than a threshold value, the reward
15 increases.
[0136]
Furthermore, assume that the sensor 5 is a vibration sensor and that a state is an
output signal of the vibration sensor provided at the bearing. When a vibration level
measured by the vibration sensor decreases, a reward is large, and, when the vibration
20 level measured by the vibration sensor increases, the reward is small. Furthermore,
when the vibration level decreases with respect to a threshold value, the reward
increases.
[0137]
Furthermore, assume that the sensor 5 is a pressure sensor and that a state is an
25 output signal of the pressure sensor that is provided at the bearing and measures an oil
film pressure in the sliding bearing. When there is a change by which an output signal
approaches a preset appropriate output signal range of the pressure sensor, a reward
increases, and, when there is a change by which the output signal moves away from the
above-described output signal range, the reward is small. Furthermore, when the
41
signal of the pressure sensor is within the above-described output signal range, the
reward increases.
[0138]
The function update unit updates a function for determining an output (learning
5 content) in accordance with a reward calculated by the reward calculation unit. For
example, in a case of the Q-learning, as a function for calculating an output (learning
content), an action-value function Q (st, at) expressed by formula 5 is used. Thus, as a
result of updating the action-value function Q by using relationship information stored in
the storage unit 8, this action-value function Q is a learned model. The learning model
10 storage unit 10 stores the obtained learned model.
[0139]
Incidentally, in Embodiment 2, although the case where the learning algorithm
used by the machine learning unit 9 is reinforcement learning has been described, the
learning algorithm is not limited to this. As the learning algorithm, supervised learning,
15 unsupervised learning, semi-supervised learning, or other learning can be used, except
for reinforcement learning.
[0140]
Furthermore, as the above-described learning algorithm, deep learning in which
feature extraction is learned can also be used, and machine learning may be performed
20 in accordance with other publicly known methods, such as a neural network, genetic
programming, inductive logic programming, and a support vector machine.
[0141]
Next, the controlled variable calculation unit 11 reads a learned model output by
the machine learning unit 9 from the learning model storage unit 10 and uses this
25 learned model to obtain information for outputting a control signal to the inverter 4 or an
operation signal to the air-conditioning apparatus or refrigeration apparatus from
actually measured state information, that is, information of the above-described physical
quantity newly measured by the sensor 5, or a voltage signal of the sensor 5.
[0142]
42
For example, in a case of the above-described Q-learning, the controlled variable
calculation unit 11 substitutes, as s, newly measured sensor output information in a
learned action-value function Q (s, a) to obtain an action a at which values of the actionvalue function Q (s, a) reach a maximum. The action a obtained in this way is output
5 as a control signal to the inverter 4 or an operation signal to the air-conditioning
apparatus or refrigeration apparatus by the controlled variable calculation unit 11.
[0143]
With respect to the learned model obtained by the above-described machine
learning unit 9, when any state information is input, if the state information is not an
10 appropriate value, that is, a value within the above-described soundness range, a signal
for appropriately controlling the rotation speed of the compressor is output so that the
state information reaches the appropriate value. Thus, the controlled variable
calculation unit 11 that calculates a controlled variable by using the learned model can
output an appropriate signal.
15 [0144]
Next, hardware that executes the storage unit 8, the machine learning unit 9, the
learning model storage unit 10, and the controlled variable calculation unit 11 in
Embodiment 2 will be described with reference to Fig. 7.
[0145]
20 In Fig. 7, a computing device 100 that performs input/output to the sensor 5 and
the inverter 4 includes a Central Processing Unit (CPU) 101, a storage device 102 that
stores a program executed by the CPU 101, primarily stores information during
calculation, and stores a calculated result, and an I/F 103 that reads a signal from the
sensor 5 that is input information, causes the storage device 102 to temporarily store
25 the signal, and extracts a result calculated by the CPU 101 from the storage device 102
to output the result to the inverter 4.
[0146]
The storage unit 8 is executed by the storage device 102. The storage unit 8
reads a signal from the sensor 5 from the I/F 103, also reads out an output signal output
30 to the inverter 4, and stores, as learning data, these signals in association with each
43
other in the storage device 102. The machine learning unit 9 is executed by the CPU
101. The machine learning unit 9 reads the storage device 102, that is, learning data
stored in the storage device 102 and causes the CPU 101 to execute a learning
program stored in the storage device 102 to output a learned model to the storage
5 device 102. The learning model storage unit 10 is executed by the storage device 102.
The controlled variable calculation unit 11 is executed by the CPU 101 in accordance
with a program stored in the storage device 102. The controlled variable calculation
unit 11 acquires a signal from a sensor 104 via the I/F 103 and causes the storage
device 102 to temporarily store the signal, and the CPU 101 uses the learned model
10 stored in the storage device 102 to calculate a controlled variable from the signal of the
sensor 104 and outputs this controlled variable to the inverter 4 via the I/F 103.
[0147]
Furthermore, the signal processing unit 7 may be implemented by the abovedescribed computing device 100. When the signal processing unit 7, the storage unit
15 8, the machine learning unit 9, the learning model storage unit 10, and the controlled
variable calculation unit 11 are implemented by the same computing device 100,
processes can be performed by one computing device 100, thus resulting in high
efficiency.
[0148]
20 Next, a process performed in Embodiment 2 will be described. In a learning
process, first, learning data is collected to create a learning data set. Through the
processing process of changing a rotation speed of the electric motor 3 described in
Embodiment 1, the rotation speed of the compressor is controlled in response to a
state, and measurement information and a rotation speed at which the electric motor 3
25 is to rotate or an operation signal transmitted to an apparatus during that time are stored
as learning data in the storage unit 8. The storage unit 8 stores, as learning data,
information of a physical quantity subjected to conversion by the signal processing unit
7, or a sensor voltage signal, and a control signal to the inverter 4 that is a result
obtained by determining a controlled variable by using information, or an operation
44
signal to the air-conditioning apparatus or refrigeration apparatus in association with
each other.
[0149]
The machine learning unit 9 creates, by using the above-described learning
5 algorithm, a learned model from information of a physical quantity subjected to
conversion by the signal processing unit 7, or a sensor voltage signal, and a control
signal to the inverter that is a result obtained by determining a controlled variable by
using information, or an operation signal to the air-conditioning apparatus or
refrigeration apparatus that are stored in the storage unit 8 and are associated with
10 each other. During this process, as the amount of learning data collected increases,
learning of the learned model progresses through the learning algorithm, and thus the
learned model that can output actions that are appropriate outputs corresponding to
various states is provided.
[0150]
15 When the learned model is created, the process proceeds to a learning model
utilization process. The controlled variable calculation unit 11 uses the learned model
for a sensor output signal currently measured to obtain a rotation speed at which the
compressor (electric motor) is to rotate or an output signal to the inverter 4 and outputs
the rotation speed or the output signal to the compressor 6 or the inverter 4. The
20 learned model is a model that is asked to output outputs appropriate to various states
by the above-described machine learning unit 9. Thus, the controlled variable
calculation unit 11 uses the learned model for the measured output signal of the sensor
5 and can output an appropriate output.
[0151]
25 In the above-described learning process, the machine learning unit 9 subjects the
above-described learning data stored in the storage unit 8 to machine learning to create
a learned model. In the early period of learning, the amount of learning data is small,
and thus, even if a learned model is created, there is a possibility that a result obtained
by the controlled variable calculation unit 11 performing calculation by using this learned
30 model does not necessarily lead to successful result.
45
[0152]
Thus, in the early period of learning, control is performed through the processing
process of changing rotation speed described in Embodiment 1, and after a
predetermined period, the compressor is controlled by a controlled variable output by
5 the controlled variable calculation unit 11 by using the learned model subjected to
learning by the above-described machine learning unit 9.
[0153]
Here, the predetermined period may be a year after the start of learning. This is
because it can be considered that nearly general conditions are learned in a year.
10 Furthermore, when the above-described processing process of changing rotation speed
is replaced during learning, the compressor 6 is controlled by a controlled variable
temporarily calculated by the controlled variable calculation unit 11 by using a learned
model subjected to learning to that time, and it may be determined whether or not to
perform switching to a full-scale learned model in accordance with whether or not a
15 sensor measurement value converges to, that is, reaches a value within a threshold
value in a predetermined period.
[0154]
Specifically, in the case where the signal processing unit 7 controls the electric
motor 3 by using a rotation speed calculated and output from an output signal measured
20 by the sensor 5, the signal processing unit 7 performs the following process. Of the
number of times the controlled variable calculation unit 11 has obtained an estimated
rotation speed in a last predetermined period, the signal processing unit 7 obtains the
number of times an estimated rotation speed obtained by the controlled variable
calculation unit 11 from an output signal calculated by the sensor 5 coincides with a
25 rotation speed calculated and output by the signal processing unit 7 from the same
output signal. Next, the signal processing unit 7 determines whether or not a
coincidence rate obtained by dividing the obtained number of times the coincidence has
occurred by the total number of times the controlled variable calculation unit 11 has
obtained an estimated rotation speed in the predetermined period exceeds a rate that is
30 a preset threshold value. When the coincidence rate exceeds the rate that is the
46
threshold value, the signal processing unit 7 performs switching so that the electric
motor 3 is controlled by using the estimated rotation speed obtained by the controlled
variable calculation unit 11. On the other hand, when the coincidence rate reaches not
more than the threshold value, the signal processing unit 7 may perform switching so
5 that the electric motor 3 is controlled by using the rotation speed calculated and output
from the output signal measured by the sensor 5.
[0155]
In the related art, even if a physical quantity representing an operating state of a
compressor is measured by a sensor, there are, for example, variations in the
10 manufacture of compressors, and thus how to control operation of the compressors
varies from compressor to compressor. When control is performed by using an
exploratory technique, it takes time to achieve convergence, and a failure occurs during
that time, or the efficiency suffers.
[0156]
15 In Embodiment 2, a sensor output value and a control value are collected as a
learning data set in association with each other and stored in the storage unit 8 in the
processing process of changing rotation speed using the exploratory technique
according to Embodiment 1. A learned model is obtained by the machine learning unit
9 from the learning data set, and the controlled variable calculation unit 11 obtains an
20 appropriate control value for a newly measured current sensor output value by using the
obtained learned model. For this reason, when a learned model is temporarily created
through learning, control can be performed without using the exploratory technique, and
thus a sensor measurement value can be quickly caused to fall within a soundness
range. In other words, the time taken for a measurement value of the sensor 5 to fall
25 within a threshold value that is the soundness range is reduced, a failure or degradation
is kept from occurring, and efficiency is also increased.
[0157]
Furthermore, if learning insufficiently takes place, there is a possibility that no
convergence may be achieved or that it may take time to achieve convergence. For
30 this reason, control performed by the controlled variable calculation unit 11 using a
47
learned model is temporarily tested. When convergence is achieved within a
predetermined time period, the processing process of changing rotation speed may be
switched to the controlled variable calculation unit 11. When convergence is not
achieved within the predetermined time period, control is returned to the processing
5 process of changing rotation speed and is performed, and learning data is further
collected. Subsequently, the machine learning unit 9 obtains a learned model
separately, and control is tested. This process is repeated until convergence is
achieved within the predetermined time period. Thus, when learning sufficiently takes
place, switching to the controlled variable calculation unit 11 is performed, and a learned
10 model can be used safely.
Reference Signs List
[0158]
1: rotating shaft, 2: bearing, sliding bearing, 3: electric motor, 4: inverter, 5:
sensor, displacement sensor, 6: compressor, refrigerant compressor, 7: signal
15 processing unit, 8: storage unit, 9: machine learning unit, 10: learning model storage
unit, 11: controlled variable calculation unit
48
We Claim :
[Claim 1]
A compressor including a rotating shaft, a sliding bearing configured to support
the rotating shaft, an electric motor configured to rotate the rotating shaft, and an
5 inverter configured to control the electric motor, the compressor comprising:
a sensor provided at the sliding bearing or a rotating shaft portion, into which the
sliding bearing is fitted, the sensor being configured to output a measured measurement
value as an output signal; and
a signal processing unit configured to perform an arithmetic operation on the
10 output signal output from the sensor to obtain a rotation speed at which the electric
motor is to rotate and configured to transmit the rotation speed as a control signal to the
inverter to control a rotation speed of the electric motor.
[Claim 2]
The compressor of claim 1, wherein the signal processing unit is configured to
15 hold a preset threshold value that is a criterion of soundness of the measurement value
of the sensor and, when the measurement value falls outside a soundness range that is
defined by a preset threshold value and in which soundness is ensured, perform
feedback control of the rotation speed of the electric motor so that the measurement
value falls within the soundness range.
20 [Claim 3]
The compressor of claim 2, wherein the sensor is a displacement sensor
configured to measure a displacement of the rotating shaft.
[Claim 4]
The compressor of claim 3, wherein the displacement sensor measures a bearing
25 clearance of the sliding bearing, and
wherein the threshold value of the signal processing unit is composed of an upper
limit threshold value and a lower limit threshold value of the measurement value of the
bearing clearance, and the soundness range is defined by the upper limit threshold
value and the lower limit threshold value.
30 [Claim 5]
49
The compressor of claim 2, wherein the sensor is a vibration sensor configured to
measure a vibration level of the sliding bearing, a temperature sensor configured to
measure a temperature of the sliding bearing, or a pressure sensor configured to
measure an oil film pressure in the sliding bearing.
5 [Claim 6]
The compressor of claim 4, wherein the threshold value of the signal processing
unit is the lower limit threshold value of the measurement value of the sensor, and the
soundness range is a range in which the measurement value exceeds the lower limit
threshold value.
10 [Claim 7]
The compressor of any one of claims 2 to 6, further comprising:
a storage unit configured to store, as association information, the measurement
value measured by the sensor, the rotation speed at which the electric motor is to rotate
obtained by the signal processing unit for this measurement value, and a measurement
15 value after control that is the measurement value of the sensor obtained as a result of
performing control to achieve the rotation speed in association with one another;
a machine learning unit configured to subject the association information stored in
the storage unit to machine learning and output a learned model; and
a controlled variable calculation unit configured to use the learned model for the
20 output signal of the sensor currently measured to estimate an estimated rotation speed
that is the rotation speed at which the electric motor is to rotate.
[Claim 8]
The compressor of claim 7, wherein the association information stored in the
storage unit includes an operation signal for an apparatus into which the compressor is
25 incorporated.
[Claim 9]
The compressor of claim 7, wherein the machine learning performed by the
machine learning unit is reinforcement learning using a value function, and
wherein the machine learning unit,
50
when the measurement value of the sensor obtained by using the rotation speed
changes from outside the soundness range to within the soundness range, constructs
the learned model by giving a reward to the value function.
[Claim 10]
5 The compressor of claim 7, wherein, of a total number of times the controlled
variable calculation unit has obtained the estimated rotation speed in a last
predetermined period, when a rate obtained by dividing, by the total number of times, a
coincidence number of times the estimated rotation speed obtained by the controlled
variable calculation unit from a measured output signal coincides with the rotation speed
10 output by the signal processing unit from the same measured output signal exceeds a
preset predetermined rate, the signal processing unit performs switching so that the
electric motor is controlled by using the estimated rotation speed obtained by the
controlled variable calculation unit.
[Claim 11]
15 An air-conditioning apparatus comprising the compressor of any one of claims 1
to 10.
[Claim 12]
A refrigeration apparatus comprising the compressor of any one of claims 1 to 10.
[Claim 13]
20 A compressor control method for controlling a compressor including a rotating
shaft, a sliding bearing configured to support the rotating shaft, an electric motor
configured to rotate the rotating shaft, and an inverter configured to control the electric
motor, the compressor control method comprising:
a measurement step of measuring a state of the sliding bearing to output a
25 measurement value obtained by a sensor provided at the sliding bearing or a rotating
shaft portion, into which the sliding bearing is fitted; and
a control step of performing an arithmetic operation on an output signal output
from the sensor to obtain a rotation speed at which the electric motor is to rotate and
transmitting the rotation speed as a control signal to the inverter to control a rotation
30 speed of the electric motor.
51
[Claim 14]
The compressor control method of claim 13, wherein, in the control step, a preset
threshold value that is a criterion of soundness of the measurement value of the sensor
is held, and, when the measurement value falls outside a soundness range that is
5 defined by a preset threshold value and in which soundness is ensured, feedback
control of the rotation speed of the electric motor is performed so that the measurement
value falls within the soundness range.
[Claim 15]
The compressor control method of claim 13 or 14, further comprising:
10 a storage step of storing, as association information, an output signal of the
sensor, the rotation speed at which the electric motor is to rotate for this output signal,
and an output signal of the sensor obtained as a result of controlling the rotation speed
in a storage unit;
a machine learning step of subjecting the association information stored in the
15 storage unit to machine learning and outputting a learned model; and
an estimation step of using the learned model for an output signal of the sensor
currently measured to estimate the rotation speed at which the electric motor is to
rotate.