FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ROTATION DETECTION DEVICE
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
Technical Field
[0001] The present invention relates to a 5 device configured
to detect rotation in a vehicle, and more particularly, to a rotation
detection device configured to detect rotation even when an ignition
switch is off.
10 Background Art
[0002] In a related-art electric power steering device, a
system for driving an electric motor is used to rotate a steering
wheel and a wheel. In such a system, when an ignition switch (power
supply switch) is on, the electric motor is driven to give assistance
15 to a steering force. Further, a rotation angle of a rotation axis
of the electric motor or a detection value of a rotation speed of
the electric motor has been used for control of drive of the motor.
[0003] Further, even when the ignition switch is off, a driver
may operate the steering wheel, or the steering wheel may be rotated
20 forcibly during repair of the vehicle. Through detection of
rotation in such a case, it is possible to start control smoothly
when an engine is started again (e.g., refer to Patent Literature
1).
25 Citation List
3
Patent Literature
[0004] [PTL 1] JP 5958572 B2
Summary of Invention
5 Technical Problem
[0005] However, the related art has the following problem.
A related-art device disclosed in Patent Literature 1 is
configured to calculate first rotation information normally when
an ignition switch is on, and calculate second rotation information
10 when the ignition switch is off, so as to enable transmission of
calculation results to a controller. Further, the related-art
device reduces a current consumed when the ignition switch is off
by setting a difference between resolutions of detection results,
for example, by setting the first rotation information and the
15 second rotation information as a rotation angle and the number of
rotations, respectively.
[0006] In other words, such a related-art device is required
to include a circuit having two types of resolutions in a rotation
detection unit. Further, a device for acquiring the second
20 rotation information is directly connected to a battery, and thus
even when the device is not required to be used, that is, even when
the device is not rotating at all, power is supplied to that device.
Therefore, there is still room for improvement in order to reduce
a dark current, which is a current flowing when the ignition switch
25 is off, to reduce current consumption.
4
[0007] The present invention has been made to solve the
above-mentioned problem, and has an object to provide a rotation
detection device capable of reducing current consumption required
for detecting rotation information while at the same time detecting
the rotation information even when an ignition 5 switch is off.
Solution to Problem
[0008] According to one embodiment of the present invention,
there is provided a rotation detection device including: a power
10 supply unit, which is connected to a battery mounted on a vehicle
and to an ignition switch, and is configured to output constant
power supply; a rotation sensor unit configured to output a
detection signal corresponding to rotation information that depends
on a rotation operation of a vehicle, by using a power supply voltage
15 supplied from the power supply unit; and a controller configured
to calculate on-time rotation information on the vehicle, which
is information at a time when the ignition switch is on, by using
a detection signal output from the rotation sensor unit, to control
a motor for the vehicle, wherein the rotation detection device
20 further includes a calculation unit configured to: control the power
supply unit to intermittently supply the power supply voltage to
the rotation sensor unit when the ignition switch is off;
intermittently supply the power supply voltage to calculate
off-time rotation information on the vehicle by using a detection
25 signal output from the rotation sensor unit; update a set value
5
of an intermittent interval, at which the power supply voltage is
to be supplied intermittently, so that the set value becomes smaller,
when the off-time rotation information contains information
indicating rotation of the motor for the vehicle; update the set
value of the intermittent interval, at which 5 the power supply
voltage is to be supplied intermittently, so that the set value
becomes larger, when the off-time rotation information on the
vehicle, which is calculated when the ignition switch is off, does
not contain the information indicating rotation of the motor for
10 the vehicle; and store the off-time rotation information into a
storage unit, and wherein the calculation unit is configured to
transfer the off-time rotation information stored in the storage
unit to the controller when the ignition switch is set on again.
15 Advantageous Effects of Invention
[0009] According to the present invention, the sensor
configured to detect rotation has a configuration of supplying a
voltage intermittently when the ignition switch is off. As a result,
it is possible to provide the rotation detection device capable
20 of reducing current consumption required for detecting rotation
information while at the same time detecting the rotation
information even when the ignition switch is off.
Brief Description of Drawings
25 [0010] FIG. 1 is a circuit diagram for illustrating an entire
6
system including a rotation detection device according to a first
embodiment of the present invention.
FIG. 2 is a circuit diagram for illustrating an entire system
including a rotation detection device according to a second
embodiment of the 5 present invention.
FIG. 3 is a graph for showing a situation of data communication
between a rotation sensor unit and a calculation unit in the second
embodiment of the present invention.
FIG. 4 is a circuit diagram for illustrating an entire system
10 including a rotation detection device according to a fourth
embodiment of the present invention.
FIG. 5 is a circuit diagram for illustrating an entire system
including a rotation detection device according to a fifth
embodiment of the present invention.
15 FIG. 6 is a circuit diagram for illustrating an entire system
including a rotation detection device according to a sixth
embodiment of the present invention.
Description of Embodiments
20 [0011] A rotation detection device according to preferred
embodiments of the present invention is described below with
reference to the accompanying drawings.
[0012] First Embodiment
FIG. 1 is a circuit diagram for illustrating an entire system
25 including a rotation detection device according to a first
7
embodiment of the present invention. The system illustrated in FIG.
1 can also be used for an electric power steering device, for
example.
[0013] The system illustrated in FIG. 1 includes a control unit
1, a battery 2, an ignition switch 3, and a motor 5 5. The motor 5
is, for example, a motor configured to give assistance to a steering
wheel. The control unit 1 includes a CPU 15 configured to calculate
and output a control amount, a drive circuit 6 configured to drive
the motor 5 in accordance with a command output by the CPU 15, and
10 a rotation detection circuit 10. The CPU 15 herein corresponds to
a controller.
[0014] A rotor 4 formed of a permanent magnet mounted to an
output shaft of the rotating motor 5 is installed outside of the
rotation detection circuit 10. In order to detect rotation of this
15 permanent magnet, a rotation sensor unit 16 inside the rotation
detection circuit 10 is arranged near the rotor 4. The steering
wheel, tires, or the like may be rotated forcibly even when the
ignition switch 3 is off, which influences an offset value or a
learned value of a rotation position, for example. Thus, it is
20 important to detect rotation of the steering wheel, tires, or the
like as information required immediately after the engine is started
again even when the ignition switch 3 is off.
[0015] The rotation detection circuit 10 has incorporated
therein a calculation unit 14 and the rotation sensor unit 16 as
25 well as three power supplies, namely, a first power supply unit
8
11, a second power supply unit 12, and a third power supply unit
13. The third power supply unit 13 is directly connected to the
battery 2. Meanwhile, the first power supply unit 11 and the second
power supply unit 12 are connected to the battery 2 via the ignition
5 switch 3.
[0016] The third power supply unit 13 is directly connected
to the battery 2, and thus power is supplied from the battery 2
to the third power supply unit 13 irrespective of whether the
ignition switch 3 is on or off. The third power supply unit 13 is,
10 for example, a constant power supply of 3.5 V, and the output of
the third power supply unit 13 is supplied to the rotation sensor
unit 16 as indicated by the symbol "○" in FIG. 1.
[0017] Meanwhile, both of the first power supply unit 11 and
the second power supply unit 12 are constant power supplies of 5
15 V. The output of the first power supply unit 11 is connected to
the CPU 15 and other components as indicated by the symbol "□" in
FIG. 1. The output of the second power supply unit 12 is connected
to the rotation sensor unit 16 as indicated by the symbol "∇". When
the outputs of the first power supply unit 11 and the second power
20 supply unit 12 are the same voltage, those power supply units may
be integrated into one constant power supply.
[0018] The rotation sensor unit 16 is connected to two power
supplies of a power supply of 5 V from the second power supply unit
12 and a power supply of 3.5 V from the third power supply unit.
25 Further, the calculation unit 14 is connected to the rotation sensor
9
unit 16. Specifically, the calculation unit 14 receives rotation
information from the rotation sensor unit 16 via a communication
line 17, and transmits a command to the rotation sensor unit 16.
Further, the calculation unit 14 also includes a memory (not shown)
for storing calculated data. Then, the calculation 5 unit 14 is
connected to the CPU 15 via a communication line 18, and is
configured to communicate information to/from the CPU 15.
[0019] Now, a description is given of a method of detecting
rotation in the device configured as described above. When the
10 ignition switch 3 is on, the CPU 15 and the rotation sensor unit
16 are supplied with 5 V from the first power supply unit 11 and
the second power supply unit 12, respectively. The rotation sensor
unit 16 detects a change in magnetic field due to rotation of the
rotor 4. A hall sensor, an MR sensor, or the like is used as the
15 rotation sensor unit 16, for example.
[0020] When the ignition switch 3 is on, the rotation sensor
unit 16 is supplied with power of 5 V from the second power supply
unit 12, and thus detailed information can be output. This detailed
information is transferred to the CPU 15 via the calculation unit
20 14. This detailed information can also be acquired directly by the
CPU 15.
[0021] When the rotation sensor unit 16 outputs both sine and
cosine waveforms, for example, the calculation unit 14 can calculate
the rotation angle based on signals of both waveforms. Further,
25 the calculation unit 14 can also calculate the rotation speed based
10
on the rotation angle. Although the calculation unit 14 can
calculate the rotation angle and the rotation speed, the CPU 15
may directly calculate the rotation angle and the rotation speed.
[0022] However, there is a risk that the remaining amount of
the battery 2 runs out unless the dark current 5 is reduced as much
as possible when the ignition switch 3 is off. In view of this,
the dark current is reduced by cutting off power supply to the first
power supply unit 11, the second power supply unit 12, the CPU 15,
and the like. Further, the dark current can be reduced more when
10 power is supplied to, for example, the CPU 15 only when the rotor
4 is rotated, and the information can be detected or stored.
[0023] The power supply of 3.5 V of the third power supply unit
13 connected to the rotor 4 is directly connected to the battery
2. The dark current can be reduced to an extremely small level by
15 avoiding supplying power when a load connected to the power supply
of 3.5V does not operate. The rotation sensor unit 16 and the
calculation unit 14 are connected as loads of the third power supply
unit 13. The calculation unit 14 consumes little current during
a period in which the rotation sensor unit 16 does not acquire
20 detection information. Further, when a volatile memory or a
non-volatile memory is used as the memory, the dark current can
be reduced to an extremely small level irrespective of the amount
of information detected during a storage period.
[0024] However, when the ignition switch 3 is off, the time
25 when the rotor 4 rotates is not known. Meanwhile, power of the third
11
power supply unit 13 is required to be supplied to the rotation
sensor unit 16 quickly at all times. Thus, in the first embodiment,
in order to suppress power consumption, the configuration of
supplying power to the rotation sensor unit 16 intermittently when
the ignition switch 3 5 is off is adopted.
[0025] The intermittent interval is determined by what
detection information based on the rotation sensor unit 16 is
required by the device. For example, when the rotation angle is
not required, and only the number of rotations is required as the
10 detection information, the calculation unit 14 supplies power to
the rotation sensor unit 16 every several seconds to check whether
rotation is detected.
[0026] The calculation unit 14 sets the intermittent interval.
When the rotation of the rotor 4 is detected under a state in which
15 power of 3.5 V is supplied from the third power supply unit 13 to
the rotation sensor unit 16, the calculation unit 14 acquires
detection information via the communication line 17, and stores
the detection information into a storage unit. In this manner, the
sensor is likely to receive input again under a state in which the
20 detection information is acquired.
[0027] In view of the above, the calculation unit 14 causes
the rotation sensor unit 16 to operate so as to reliably detect
the number of rotations by reducing an interval of power supply
or by continuously supplying power for a certain period of time.
25 Thus, the third power supply unit 13 and the calculation unit 14
12
are connected to each other via a line 19, and the calculation unit
14 controls via the line 19 an interval of power supply by the third
power supply unit 13 to be variable.
[0028] Meanwhile, the rotation sensor unit 16 may be a single
sensor, but it is assumed that the rotation sensor 5 unit 16 includes
a circuit configured to change output of detection information based
on a difference of a constant power supply supplied thereto. That
is, the rotation sensor unit 16 transmits detailed data when 5 V
is supplied from the second power supply unit 12. Meanwhile, when
10 3.5 V is supplied from the third power supply unit 13, the rotation
sensor unit 16 operates not to transmit detailed detection
information, but to transmit detection information being simplified
data or intermittent data.
[0029] There may be adopted a configuration in which the
15 rotation sensor unit 16 outputs continuous waveforms in accordance
with the power supply voltage, and the calculation unit 14 sets
the degree of resolutions of the detection information based on
the reading interval. In general, as the power supply voltage
becomes lower, the current consumption tends to be smaller. Thus,
20 it is desired to change, for example, the accuracy of detection
information, the resolution, and the number of rotations depending
on whether the ignition switch 3 is on or off.
[0030] After the ignition switch 3 is set off, when the
ignition switch 3 is set on again, the first power supply unit 11
25 and the second power supply unit 12 start to supply power. Thus,
13
the CPU 15 starts an operation, and requires the calculation unit
14 for data on the number of rotations, which is stored when the
ignition switch 3 is off. The calculation unit 14 transmits the
required data on the number of rotations to the CPU 15 via the
communication line 18. As a result, the CPU 5 15 can grasp the
situation of rotation during a period in which the ignition switch
3 is off at the time of starting an operation, and can reflect the
situation in start of control.
[0031] Although the calculation unit 14 is supplied with power
10 from both of the second power supply unit 12 and the third power
supply unit 13, the CPU 15 is not supplied with power from the second
power supply unit 12. Thus, there is a risk that, when a difference
between the output voltage of the second power supply unit 12 and
the third power supply unit 13 and the output voltage of the first
15 power supply unit 11 occurs, a detection error between the CPU 15
and the calculation unit 14 occurs.
[0032] As a countermeasure for this risk, it is possible to
suppress the error by supplying power to the CPU 15 with the output
voltage of the second power supply unit 12 serving as a reference
20 when the ignition switch 3 is on. Further, the first power supply
unit 11 can also be arranged outside of the rotation detection
circuit 10 and at a position inside the control unit 1.
[0033] As described above, in the first embodiment, there is
provided the configuration of enabling, when the ignition switch
25 is off, the rotation sensor unit 16 to be supplied with power in
14
a different mode from a constant power supply that is different
from a constant power supply used when the ignition switch is on.
Specifically, in a case where a mode of supplying, when the ignition
switch is off, a lower voltage than a voltage used when the ignition
switch is on is adopted, current consumption required 5 for acquiring
detection information from the rotation sensor unit 16 when the
ignition switch is off can be reduced.
[0034] Further, when a mode of intermittently supplying power
when the ignition switch is off is adopted, the dark current can
10 be reduced. Further, in a case where rotation is detected under
a state in which power is intermittently supplied when the ignition
switch is off, the intermittent interval can be changed to be smaller.
Thus, it is also possible to prevent a failure to detect rotation.
The mode of changing the power supply voltage and the mode of
15 changing the intermittent interval described above both change the
resolution detected by the rotation sensor unit.
[0035] Further, the device according to the first embodiment
has integrated three power supply units into one power supply
circuit. As a result, there is also an advantage of enabling
20 consideration of commonalization, common use, or the like of
components at the time of actual circuit design. Therefore, it is
possible to implement the rotation detection device capable of
reducing current consumption required for detecting rotation
information as much as possible while at the same time detecting
25 the rotation information even when the ignition switch is off.
15
[0036] Second Embodiment
In the configuration illustrated in FIG. 1 of the first
embodiment, only the third power supply unit 13 connected to the
battery 2 operates when the ignition switch is off. Further, in
the configuration of FIG. 1, power is not required 5 to be supplied
to the rotation sensor unit 16 unless the rotor 4 rotates. In view
of the above, in a second embodiment of the present invention, a
description is given of a rotation detection device having a power
supply configuration different from that of the first embodiment.
10 [0037] FIG. 2 is a circuit diagram for illustrating an entire
system including a rotation detection device according to the second
embodiment of the present invention. In FIG. 2, components
equivalent to those of FIG. 1 of the first embodiment are denoted
by the same reference symbols. The system illustrated in FIG. 2
15 includes the control unit 1, the battery 2, the ignition switch
3, and the motor 5. FIG. 2 is different from FIG. 1 of the first
embodiment in the configuration of the control unit 1.
[0038] In the configuration illustrated in FIG. 2, the second
power supply unit 12 is supplied with power also from the battery
20 2. Further, in the configuration of FIG. 2, the first power supply
unit 11 and the second power supply unit 12 in the configuration
of FIG. 1 are integrated into the second power supply unit 12. With
such a configuration, the CPU 15 is supplied with power from the
second power supply unit 12 even after the ignition switch 3 is
25 set off.
16
[0039] Further, similarly to the configuration of FIG. 1, the
first power supply unit 11 and the second power supply unit 12 may
be divided also in the configuration of FIG. 2. In that case, when
the ignition switch is on, the first power supply unit 11 supplies
power to the CPU 15, and the second power supply 5 unit 12 supplies
power to the sensor.
[0040] In view of the above, when the CPU 15 detects the fact
that the ignition switch 3 is set off, the CPU 15 activates the
third power supply unit 13, and the calculation unit 14 also
10 recognizes this activation. After that, the CPU 15 stops power
supply to the second power supply unit 12 directly connected to
the battery 2, and the CPU 15 itself deactivates itself.
[0041] Meanwhile, the third power supply unit 13 and the
calculation unit 14 are already activated. Thus, while the
15 ignition switch 3 is off, the calculation unit 14 supplies power
from the third power supply unit 13 to a rotation sensor unit 16a
at an interval set in advance, and checks whether the rotor 4 is
rotating. When the rotation is detected, the calculation unit 14
shortens an interval of power supply or continuously supplies power
20 for a while. Further, when the rotation is no longer detected, the
calculation unit 14 gradually increases the interval of power supply
to return to the original state.
[0042] Now, a description is given of a specific configuration
illustrated in FIG. 2 of a more detailed rotation detection method
25 in the second embodiment. A rotation detection circuit 10a
17
includes two types of power supply units for the rotation sensor
unit 16a, namely, the second power supply unit 12 and the third
power supply unit 13, and is configured to supply different voltages
of 5 V and 3.5 V to the second power supply unit 12 and the third
power supply unit 5 13, respectively.
[0043] The second power supply unit 12 includes both of a path
connected to the battery 2 via the ignition switch 3 and a path
directly connected to the battery 2. Meanwhile, the third power
supply unit 13 is directly connected to the battery 2.
10 [0044] The calculation unit 14 is configured to control, via
a control command line 19a, a selector 20 configured to select and
output a constant power supply unit of any one of the second power
supply unit 12 and the third power supply unit 13. The calculation
unit 14 connects the selector 20 to the second power supply unit
15 12 when the ignition switch 3 is off and is not driven intermittently.
Meanwhile, the calculation unit 14 connects the selector 20 to the
third power supply unit 13 only while the ignition switch 3 is off
and is driven intermittently.
[0045] As described above, the voltage of 5 V is output from
20 the second power supply unit 12 until the CPU 15 confirms the fact
that the ignition switch 3 is set off. Then, the CPU 15 activates
the third power supply unit 13 after confirming the fact that the
ignition switch 3 is set off. Further, the calculation unit 14 sets
off the constant power supply of the second power supply unit 12
25 after the third power supply unit 13 is activated.
18
[0046] The rotation sensor unit 16a illustrated in FIG. 2
includes a sensor unit 21, an amplifier 22, and a communicator 23.
In the second embodiment, the sensor unit 21 includes, for example,
a bridge circuit formed of four variable resistors, and the
resistance value of each of those variable resistors 5 is changed
depending on the magnetic field of the rotor 4.
[0047] The amplifier 22 is configured to receive input of
voltages of left and right center points of the bridge circuit 21,
and amplify a difference between those voltages. The communicator
10 23 is configured to communicate data to/from the calculation unit
14 to output a signal of the rotation sensor, or receive a command
from the calculation unit 14.
[0048] The amplifier 22 and the communicator 23 are configured
to operate by a power supply voltage equivalent to that of the bridge
15 circuit 21. Thus, the resolution of the rotation sensor unit 16a
in a case where 5 V is supplied when the ignition switch is on and
the resolution of the rotation sensor unit 16a in a case where 3.5
V is supplied when the ignition switch is off are different from
each other.
20 [0049] FIG. 3 is a graph for showing a situation of data
communication between the rotation sensor unit 16a and the
calculation unit 14 in the second embodiment of the present
invention. The horizontal axis represents time, and the vertical
axis represents the magnitude of the voltage of each piece of data.
25 It is assumed that the ignition switch 3 is set on and is supplied
19
with power of 5 V at a time point of t0.
[0050] When the ignition switch 3 is set on and the second power
supply unit 12 of FIG. 2 is thus turned on, the calculation unit
14 acquires data from the rotation sensor unit 16a at time points
t1, t2, and t3 set in advance as short intervals. 5 With this, the
calculation unit 14 can sequentially acquire the detection value
of the bridge circuit 21, and grasp the rotation angle in detail.
[0051] The ignition switch 3 is set off at a time point of t4
to cause the calculation unit 14 to switch to supply power
10 intermittently to the rotation sensor unit 16a. Specifically, at
a time point of t5, at which a certain period of time has elapsed
since the time point of t4, the calculation unit 14 supplies the
rotation sensor unit 16a with the voltage of 3.5 V output from the
third power supply unit 13. Then, at a time point of t6, at which
15 a short period of time has elapsed since the time point of t5, the
calculation unit 14 reads an output signal of the rotation sensor
unit 16a.
[0052] An interval between the time point of t5 and the time
point of t6 is a period of time required for a wait until the power
20 supply of 3.5 V becomes stable, and thus the interval can be set
to a relatively short period of time. In FIG. 3, as described later,
there is exemplified a case in which detection information
indicating rotation has failed to be acquired from the rotation
sensor unit 16a at the time point of t6 and a time point of t9,
25 and detection information indicating rotation has successfully been
20
acquired at a time point of t12.
[0053] The calculation unit 14 has failed to acquire detection
information indicating rotation at the time point of t6, and thus
temporarily stops power supply at a time point of t7. Then, after
a while, similarly to the time point t5 to the 5 time point t7, the
calculation unit 14 performs a series of operations, that is,
supplying power at t8, reading detection information at t9, and
cutting off power supply at t10.
[0054] When the calculation unit 14 has successfully acquired
10 detection information indicating rotation as a result of supplying
power again at a time point of t11 and reading detection information
at a time point of t12, the calculation unit 14 does not cut off
power supply at a time point of t13 and continues to supply power
for a while. Then, the calculation unit 14 acquires detection
15 information again at a time point of t14 while supplying power.
[0055] When the calculation unit 14 has failed to acquire
detection information indicating rotation at the time point of t14,
the calculation unit 14 temporarily cuts off power supply, and
supplies power again at a time point of t15 at an interval shorter
20 than the previous interval. When the calculation unit 14 has
successfully acquired detection information indicating rotation
also at the time point of t14, the calculation unit 14 continuously
supplies power and interrupts intermittent supply.
[0056] After the calculation unit 14 has supplied power again
25 at the time point of t15, the calculation unit 14 reads detection
21
information at a time point of t16. Then, when the calculation unit
14 has failed to acquire detection information indicating rotation
also at the time point of t16, the calculation unit 14 reads
detection information again at a time point of t17. When the
calculation unit 14 has failed to acquire detection 5 information
indicating rotation even through two times of reading, the
calculation unit 14 operates so as to return the interval to a longer
interval having an original length as shown at the time points of
t5, t8, and t11, supply power intermittently, and sample detection
10 information. When the calculation unit 14 has successfully
acquired detection information indicating rotation, the
calculation unit 14 stores the information into the memory.
[0057] As described above, in the second embodiment, the CPU
is supplied with power immediately after the ignition switch is
15 set off. As a result, after the ignition switch is set off, the
third power supply unit, the calculation unit, and the rotation
sensor unit can be activated so as to perform an operation at the
time when the ignition switch is off based on determination by the
CPU.
20 [0058] Further, after the CPU has confirmed completion of its
activation, the CPU stops its operation and causes the calculation
unit 14 to take over subsequent control. As a result, similarly
to the first embodiment described above, it is possible to implement
the rotation detection device capable of reducing current
25 consumption required for detecting rotation information as much
22
as possible while at the same time detecting the rotation
information even when the ignition switch is off.
[0059] Further, when the interval of operating the rotation
sensor intermittently can be changed to be shortened, rotation can
be detected quickly at a shorter interval compared 5 to a case in
which the interval can be changed to return to an original interval.
As a result, it is possible to acquire detection information at
an appropriate timing so as to prevent a failure to detect rotation.
[0060] Through adoption of such a configuration in the second
10 embodiment, the rotation sensor unit itself can use the same circuit
network to handle both of the case in which the ignition switch
is on and the case in which the ignition switch is off. As a result,
two types of circuits are not required to be used as the rotation
sensor unit individually for the case in which the ignition switch
15 is on and the case in which the ignition switch is off, and an
advantage of simplifying the circuit network can be obtained.
[0061] When the interval of intermittent operation can be
changed, the interval may be changed to a short interval or
conversely to a long interval in accordance with change in detection
20 signal, for example, an acceleration.
[0062] Further, the rotation detection device according to the
second embodiment is configured to store, into the memory,
information indicating rotation detected when the ignition switch
is off. Thus, there can be provided a configuration in which the
25 circuit detection circuit is supplied with power in a concentrated
23
manner when the ignition switch is off, and a part of output by
the circuit detection circuit is supplied to the rotation sensor
unit. Therefore, compared with a configuration in which power is
supplied to both of the calculation unit and the sensor unit
independently when the ignition switch is 5 off, the circuit
configuration can be simplified, and the size of the device, in
particular, the size of the sensor unit, can be reduced.
[0063] Third Embodiment
The configuration of a rotation detection device according
10 to a third embodiment of the present invention is similar to those
of the first embodiment and the second embodiment. That is, the
calculation unit 14 performs a substantial operation when the
ignition switch 3 is off. The calculation unit 14 in the third
embodiment is different from the calculation units 14 in the first
15 and second embodiments in that the calculation unit 14 has a function
of being able to calculate and store the rotation angle in parallel
with the CPU 15 even when the ignition switch 3 is on.
[0064] In view of the above, the rotation detection device
according to the third embodiment can use this function to compare
20 the rotation angle calculated by the CPU 15 with the rotation angle
calculated by the calculation unit 14 when the ignition switch 3
is on, and determine whether the calculation unit 14 and the CPU
15 are normal or abnormal based on whether those rotation angles
match each other. In general, the CPU 15 has better calculation
25 speed and accuracy than the calculation unit 14. Thus, the
24
calculation unit 14 and the CPU 15 are required to determine whether
the calculation unit 14 and the CPU 15 are normal or abnormal by
ensuring a certain degree of margin for the difference between both
rotation angles.
[0065] For example, it is assumed that, compared 5 with the CPU
15, the interval of inputting detection information by the rotation
sensor unit 16 is twice and the calculation unit 14 has a slower
speed. In this case, the resolution of the calculation unit 14 is
about half a resolution of the CPU 15. Thus, when the result of
10 calculation by the calculation unit 14 and the result of calculation
by the CPU 15 are compared with each other, it is required to ensure
a margin that depends on the difference between both resolutions.
[0066] The calculation unit 14 transfers the calculated
rotation information to the CPU 15. The CPU 15 compares the rotation
15 information acquired from the calculation unit 14 with the rotation
information calculated by itself, and when both pieces of rotation
information match each other in consideration of the margin, the
CPU 15 determines that both pieces of rotation information are
normal.
20 [0067] When the CPU 15 determines that both pieces of rotation
information do not match each other, the CPU 15 calculates an
estimation value of the rotation information in consideration of
the control amount calculated and output by itself. Then, the CPU
15 compares the estimation value with each of the pieces of rotation
25 information calculated by the CPU 15 and the calculation unit 14,
25
and determines which one of the pieces of rotation information is
more appropriate.
[0068] In this determination, rotation information closer to
the estimation value may not always be determined to be more
appropriate. For example, even in a case where 5 one of the pieces
of rotation information is closer to the estimation value in terms
of the absolute value, when the rotation directions are different
from each other and the other one of the pieces of rotation
information has the same rotation direction as that of the
10 estimation value, the other one of the pieces of rotation
information may be determined to be more appropriate. Thus, the
CPU 15 identifies more appropriate rotation information by
considering the rotation direction as well as the deviation from
the estimation value.
15 [0069] When the CPU 15 determines that the rotation
information calculated by the CPU 15 is normal, the CPU 15 can
continue the control. On the contrary, when the CPU 15 determines
that the rotation information calculated by the calculation unit
14 is more appropriate than the rotation information calculated
20 by the CPU 15, the CPU 15 can continue control based on the rotation
information calculated by the calculation unit 14.
[0070] The resolution of rotation information calculated by
the calculation unit 14 is inferior to the resolution of rotation
information calculated by the CPU 15, and thus the CPU 15 is required
25 to perform correction in consideration of the difference in
26
resolution when calculating the control amount. Control can be
continued irrespective of which one of the pieces of rotation
information is to be adopted, and it is possible to continue to
drive the vehicle for a while.
[0071] As described above, in the third embodiment, 5 there is
provided the configuration of comparing the result of calculating
rotation information by the CPU and the result of calculating
rotation information by the calculation unit inside the rotation
detection circuit when the ignition switch is on. As a result, it
10 is possible to determine validity of the result of calculating
rotation information by the CPU when the ignition switch is on.
Further, even in a case where the result of calculating rotation
information by the CPU is not valid, when the result of calculating
rotation information by the calculation unit is valid, the rotation
15 information calculated by the calculation unit can be used to
continue control.
[0072] Fourth Embodiment
FIG. 4 is a circuit diagram for illustrating an entire system
including a rotation detection device according to a fourth
20 embodiment of the present invention. Components equivalent to
those of FIG. 1 of the first embodiment are denoted by the same
reference symbols.
[0073] A rotation detection circuit 10b in the fourth
embodiment includes two types of power supply units, namely, the
25 first power supply unit 11a and the third power supply unit 13a.
27
The first power supply unit 11a is directly supplied with a current
from the battery 2. Further, the first power supply unit 11a reads
an on/off state of the ignition switch 3 via a line 24. Further,
the first power supply unit 11a is configured not to be activated
when the ignition switch 3 is not set on. This 5 first power supply
unit 11a is a power supply configured to supply power of 5 V to
the CPU 15.
[0074] Meanwhile, the third power supply unit 13a is directly
supplied with a current from the battery 2. Further, the third power
10 supply unit 13a reads the on/off state of the ignition switch 3
via the line 24. Then, the third power supply unit 13a outputs 5
V as the constant power supply for the rotation sensor unit 16 when
the ignition switch 3 is on. Alternatively, the third power supply
unit 13a outputs 3.5 V as the constant power supply for the rotation
15 sensor unit 16 when the ignition switch 3 is not set on.
[0075] That is, the third power supply unit 13a is configured
to switch the output voltage in accordance with the on/off state
of the ignition switch 3. This switching is not limited to
components that directly depend on the ignition switch 3, and the
20 calculation unit 14a may determine the state of the ignition switch
3 and switch the output voltage. With the latter method of switching
by the calculation unit 14a, the output voltage can be switched
in consideration of an appropriate delay for an on/off operation
of the ignition switch 3.
25 [0076] Further, the calculation unit 14a is connected to the
28
rotation sensor unit 16 via the communication line 17a. Meanwhile,
a shut-off unit 25, which can be switched by the calculation unit
14a, is inserted into a communication line 17b configured to connect
the calculation unit 14a to the CPU 15. With such a configuration,
it is possible to prevent a redundant signal from 5 flowing to the
CPU 15 by shutting off the communication line 17b with the shut-off
unit 25 when the ignition switch 3 is off. Meanwhile, the shut-off
unit 25 is switched to the on state to connect the communication
line 17b only when the ignition switch 3 is on.
10 [0077] As described above, in the fourth embodiment, there is
provided the configuration of enabling control of switching the
output of the constant power supply in accordance with the state
of the ignition switch. As a result, there is provided an effect
of achieving simplification of the circuit network of the rotation
15 detection circuit and reducing the size and cost of the circuit
network.
[0078] Further, the output of the constant power supply of the
third power supply unit 13a is supplied to the CPU 15 as the reference
voltage when the ignition switch 3 is on, to thereby enable the
20 CPU 15 to suppress the detection error with respect to the
calculation unit 14a.
[0079] The constant power supply of the third power supply unit
13a may be one power supply of 3.5 V. In that case, the constant
power supply of 3.5 V is required to be supplied to the CPU 15 as
25 the reference voltage when the ignition switch 3 is on. With this,
29
the CPU 15 can suppress the detection error with respect to the
calculation unit 14a.
[0080] Fifth Embodiment
FIG. 5 is a circuit diagram for illustrating an entire system
including a rotation detection device according 5 to a fifth
embodiment of the present invention. Components equivalent to
those of FIG. 4 of the fourth embodiment are denoted by the same
reference symbols.
[0081] A motor 5a in the fifth embodiment is a three-phase
10 winding motor. Thus, a drive circuit 6a also supplies power to the
motor 5a via output lines corresponding to three phases. In the
fifth embodiment, a monitor circuit 26 configured to monitor the
voltages of the output lines corresponding to three phases is added.
[0082] The monitor circuit 26 integrates the voltages
15 generated in the output lines into one voltage by a wired OR, and
transmits the voltage to the calculation unit 14a. The monitor
circuit 26 monitors each terminal voltage of the motor 5. When the
ignition switch 3 is off and the motor 5 is rotated forcibly, an
induced voltage is generated in a winding. Then, the generated
20 induced voltage is input to the calculation unit 14a via the monitor
circuit 26 when the generated induced voltage is equal to or larger
than a value set in advance.
[0083] The monitor circuit 26 is included, to thereby enable
the calculation unit 14a to change the intermittent interval to
25 be a long period of time, and reduce the dark current. Further,
30
the monitor circuit 26 is included, to thereby enable rotation of
the motor to be monitored at all times through the induced voltage,
and prevent a failure to detect rotation.
[0084] When the monitor circuit 26 monitors the induced
voltage of the motor and a voltage of a set level or 5 more is generated,
the voltage generated as the induced voltage is input to the
calculation unit 14a. Through input of this generated voltage into
the calculation unit 14a, the calculation unit 14a can immediately
supply power when the ignition switch 3 is off. That is, the monitor
10 circuit 26 detects the induced voltage so as to cause the calculation
unit 14a to wake up.
[0085] After the calculation unit 14a supplies power by the
monitor circuit 26, the calculation unit 14a can continue to supply
power continuously for a while. Further, when the calculation unit
15 14a fails to acquire detection information indicating rotation
during continuous power supply, the calculation unit 14a can also
interrupt power supply to stop intermittent supply.
[0086] Further, the third power supply unit 13 can also be
configured to output the same voltage irrespective of whether the
20 ignition switch 3 is on or off. Even when the configuration of
outputting the same power supply is adopted, it is possible to reduce
current consumption by supplying power intermittently when the
ignition switch is off.
[0087] As described above, in the fifth embodiment, there is
25 provided the configuration of detecting an induced voltage
31
generated when the motor is rotated forcibly, to thereby wake up
the calculation unit. As a result, it is possible to change the
intermittent interval to be a long period of time, to thereby
reliably prevent a failure to detect rotation while at the same
time reducing 5 the dark current.
[0088] Sixth Embodiment
FIG. 6 is a circuit diagram for illustrating an entire system
including a rotation detection device according to a sixth
embodiment of the present invention. Components equivalent to
10 those of FIG. 1 of the first embodiment are denoted by the same
reference symbols. FIG. 6 is different from the configuration of
FIG. 1 in that the rotation sensor is a resolver 27. A rotation
sensor unit 16b being a resolver outputs an excitation signal 27a,
and receives input of a sine signal 27b and a cosine signal 27c.
15 Then, the calculation unit 14 calculates the angle of the motor
5 based on the sine signal 27b and the cosine signal 27c.
[0089] Thus, the rotation sensor unit 16b configured to output
and input each signal is connected to the calculation unit 14.
Similarly to the first to fifth embodiments, the rotation sensor
20 unit 16b outputs the excitation signal 27a by the power supply of
5 V when the ignition switch 3 is on. On the contrary, the rotation
sensor unit 16b outputs the excitation signal 27a by the power supply
of 3.5 V when the ignition switch 3 is off.
[0090] When the sine signal 27b and the cosine signal 27c being
25 detection signals are checked, the calculation unit 14 performs
32
monitoring at both timings of a peak and a valley of an excitation
signal 26a when the ignition switch 3 is on. On the contrary, when
the ignition switch 3 is off, the calculation unit 14 performs
monitoring at only the timing of a peak of the excitation signal
27a or only the timing of a valley of the excitation 5 signal 27a.
Further, when the ignition switch 3 is off, the calculation unit
14 can also perform monitoring by skipping one peak.
[0091] As described above, in the sixth embodiment, there is
provided the configuration of changing not only the power supply
10 voltage but also the monitoring interval, namely, the resolution,
in accordance with the state of the ignition switch 3, and monitoring
rotation of the motor. As a result, it is therefore possible to
implement the rotation detection device capable of further reducing
current consumption required for detecting rotation information
15 while at the same time detecting the rotation information even when
the ignition switch is off.
[0092] The second power supply unit 12 and the third power
supply unit 13 may output the same voltage. However, if possible,
it is desired to provide the configuration of setting a difference
20 for the supplied current depending on whether the ignition switch
3 is on or off, and supplying a larger amount of current when the
ignition switch 3 is on than when the ignition switch 3 is off.
[0093] Further, the rotation sensor is not limited to a
magnetic sensor, and even when the rotation sensor is a resolver
25 of an AC generator, the rotation sensor can suppress current
33
consumption in a similar manner. Further, in each of the
embodiments described above, the power supply voltage is changed
in accordance with the situation of the ignition switch. However,
the present invention is not limited to such a configuration. The
configuration may be to perform detection at 5 a low power supply
voltage irrespective of the situation of the ignition switch. In
this case, the current consumption is suppressed by change in
resolution due to intermittent detection.
10 Reference Signs List
[0094] 1 control unit, 2 battery, 3 ignition switch, 4 rotor,
5, 5a motor, 6, 6a drive circuit, 10, 10a, 10b, 10c, 10d, rotation
detection circuit, 11, 12, 13 power supply unit, 14, 14a calculation
unit, 15 CPU, 16, 16a, 16b rotation sensor unit, 20 selector, 26
15 monitor circuit, 27 resolver
34
We Claim :
[Claim 1] A rotation detection device, comprising:
a power supply unit, which is connected to a battery mounted
on a vehicle and to an ignition switch, and is configured to output
constant 5 power supply;
a rotation sensor unit configured to output a detection signal
corresponding to rotation information that depends on a rotation
operation of a vehicle, by using a power supply voltage supplied
from the power supply unit; and
10 a controller configured to calculate on-time rotation
information on the vehicle, which is information at a time when
the ignition switch is on, by using a detection signal output from
the rotation sensor unit, to control a motor for the vehicle,
wherein the rotation detection device further comprises a
15 calculation unit configured to:
control the power supply unit to intermittently supply
the power supply voltage to the rotation sensor unit when the
ignition switch is off;
intermittently supply the power supply voltage to
20 calculate off-time rotation information on the vehicle by using
a detection signal output from the rotation sensor unit;
update a set value of an intermittent interval, at which
the power supply voltage is to be supplied intermittently, so that
the set value becomes smaller, when the off-time rotation
25 information contains information indicating rotation of the motor
35
for the vehicle;
update the set value of the intermittent interval, at
which the power supply voltage is to be supplied intermittently,
so that the set value becomes larger, when the off-time rotation
information on the vehicle, which is calculated 5 when the ignition
switch is off, does not contain the information indicating rotation
of the motor for the vehicle; and
store the off-time rotation information into a storage
unit, and
10 wherein the calculation unit is configured to transfer the
off-time rotation information stored in the storage unit to the
controller when the ignition switch is set on again.
[Claim 2] The rotation detection device according to claim 1,
15 wherein, when the ignition switch is off, the rotation sensor unit
outputs the detection signal as a signal with a higher resolution,
as an intermittent interval of the power supply voltage
intermittently supplied from the power supply unit becomes smaller.
20 [Claim 3] The rotation detection device according to claim 1 or
2, wherein the rotation sensor unit is configured to output the
detection signal as a signal with a higher resolution, as a value
of the power supply voltage supplied from the power supply unit
becomes larger.
25
36
[Claim 4] The rotation detection device according to any one of
claims 1 to 3, wherein the power supply unit includes:
an on-time power supply unit configured to generate an on-time
power supply voltage when the ignition switch is on; and
an off-time power supply unit configured 5 to generate an
off-time power supply voltage when the ignition switch is off.
[Claim 5] The rotation detection device according to claim 4,
wherein the motor for the vehicle includes a motor having
10 phase windings,
wherein the rotation detection device further comprises a
monitor circuit configured to detect a state in which a voltage
of each of winding terminals of the motor for the vehicle exceeds
an allowable voltage value set in advance, and
15 wherein the calculation unit is configured to start an
operation of intermittently supplying the off-time power supply
voltage to the rotation sensor unit when the monitor circuit has
detected the state in which the allowable voltage value is exceeded.
20 [Claim 6] The rotation detection device according to claim 4 or
5, wherein the off-time power supply voltage generated by the
off-time power supply unit is set to be a value smaller than the
on-time power supply voltage generated by the on-time power supply
unit.
25
37
[Claim 7] The rotation detection device according to any one of
claims 4 to 6, wherein the power supply unit is configured to
generate the on-time power supply voltage and the off-time power
supply voltage as the same value.
5
[Claim 8] The rotation detection device according to claim 7,
wherein the calculation unit is configured to generate
rotation information for comparison by intermittently using a
detection signal output from the rotation sensor unit when the
10 ignition switch is on, and sequentially transfer the rotation
information for comparison to the controller, and
wherein the controller is configured to:
compare the on-time rotation information on the vehicle
generated by the controller with the rotation information for
15 comparison; and
determine that the on-time rotation information on the
vehicle has been generated normally when a difference between the
on-time rotation information on the vehicle and the rotation
information for comparison falls within an allowable range set in
20 advance.
[Claim 9] The rotation detection device according to any one of
claims 4 to 8,
wherein the rotation sensor unit includes a single detection
25 circuit in which a power supply voltage supplied from an outside
is one system,
wherein the rotation detection device
selector configured to select any one of the on
voltage and the off-time power supply voltage generated by the
supply unit in accordance with an external command, 5 and supply a
selected power supply voltage to the rotation sensor unit, and
wherein the calculation unit is configured to:
generate the external command so as to supply the
on-time power supply voltage to the rotation sensor unit when the
10 ignition switch is on;
generate the external command so as to supply the
off-time power supply
ignition switch is off; and
execute control of switching the selector.