FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
HERMETIC COMPRESSOR
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
5 [0001]
The present invention relates to a hermetic compressor for use in, for example,
a freezing apparatus, an air-conditioning apparatus, or a water heater.
Background Art
[0002]
10 In a refrigeration cycle of a related-art freezing apparatus or other apparatuses,
an abnormal high pressure may be generated in a compressor due to, for example,
an unexpected increase in condensing temperature, which is caused by an
abnormality of a cooling fan of a condenser. When the abnormal high pressure is
generated in the compressor, a compression operation of the compressor is generally
15 stopped by a high-pressure cutting protector provided on a discharge side of the
compressor. If an abnormality occurs in an operation of the high-pressure cutting
protector, however, a pressure beyond a permissible level may be applied to the
refrigeration cycle to cause damage to, for example, a pipe at a part of the
refrigeration cycle except the compressor. In view of this, a brittle portion is provided
20 at a part of the pipe in the refrigeration cycle and is covered with a coating. When
the abnormal high pressure is generated in the compressor, damage to the refrigerant
pipe can be caused at the brittle portion but expansion of the damage can be
prevented by the coating (see, for example, Patent Literature 1).
Citation List
25 Patent Literature
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2000-130896
Summary of Invention
30 Technical Problem
3
[0004]
If air enters the compressor from a suction side of the compressor, the air is
compressed while refrigerating machine oil is present in the compressor in the form of
mist. Therefore, a pressure on a high-pressure side of the compressor may
abnormally increase at an extremely high rate. In this case, the 5 compressor and the
pipe connected to the compressor are damaged. Further, for example, equipment
around the compressor may also be damaged. Therefore, there is a demand to
prevent such damage. However, the structure of the brittle portion of the refrigerant
pipe in Patent Literature 1 is provided under the assumption of damage to the
10 refrigerant pipe due to a load caused by abnormal increase in the refrigerant pressure
or repeated changes in the refrigerant pressure. Thus, the structure described in
Patent Literature 1 cannot be a remedy for the case where the pressure on the highpressure
side of the compressor abnormally increases at an extremely high rate.
[0005]
15 The present invention has been made to solve the problems described above
and has an object to provide a hermetic compressor in which damage to, for example,
equipment around the compressor can be prevented even if a pressure in the
compressor abnormally increases at an extremely high rate.
Solution to Problem
20 [0006]
A hermetic compressor according to an embodiment of the present invention
includes a hermetic container, a compression mechanism contained in the hermetic
container and configured to compress refrigerant, and an electric motor contained in
the hermetic container and configured to drive the compression mechanism. The
25 compression mechanism includes a hollow cylinder, a crankshaft to be rotated by the
electric motor, a rolling piston fitted to an eccentric shaft of the crankshaft and
configured to eccentrically rotate along an inner peripheral surface of the cylinder, a
vane that partitions a compression chamber for the refrigerant into a high-pressure
area and a low-pressure area, the compression chamber being defined by the inner
30 peripheral surface of the cylinder and an outer peripheral surface of the rolling piston,
4
and a spring that urges the vane against the outer peripheral surface of the rolling
piston so that the vane follows eccentric rotation of the rolling piston. The hermetic
compressor includes a housing provided to a barrel of the hermetic container and
housing the spring. The housing has a brittle portion, which is lower than the
hermetic container in terms of a strength against an external force from 5 an axis center
of the crankshaft to an outside of the hermetic container. The housing
communicates with the compression chamber. The housing is positioned so that a
length from the axis center of the crankshaft to the brittle portion in a radial direction
of the cylinder is not smaller than a length from the axis center of the crankshaft to an
10 outer peripheral surface of the hermetic container in the radial direction of the
cylinder.
Advantageous Effects of Invention
[0007]
In the hermetic compressor according to the embodiment of the present
15 invention, even if gas in the compression chamber abruptly expands at an extremely
high rate and the pressure in the compression chamber abnormally increases, the
brittle portion is ruptured with precedence over the other components of the
compression mechanism. Therefore, the high-pressure space in the hermetic
container no longer has hermeticity and the pressure increase can be prevented.
20 Thus, damage to the compressor and damage to a pipe connected to the compressor
are prevented. Accordingly, damage to, for example, equipment around the
compressor can be prevented.
Brief Description of Drawings
[0008]
25 [Fig. 1] Fig. 1 is a vertical sectional view of a hermetic compressor according to
Embodiment of the present invention.
[Fig. 2] Fig. 2 is a plan view illustrating a compression mechanism of the
hermetic compressor according to Embodiment of the present invention.
[Fig. 3] Fig. 3 is a diagram illustrating the structure of a housing according to
30 Embodiment of the present invention.
5
Description of Embodiments
[0009]
A hermetic compressor according to Embodiment of the present invention is
described below in detail with reference to the drawings. Note that the present
invention is not limited to Embodiment. Further, the sizes 5 and shapes of
components in the drawings may differ from the sizes and shapes of components of
an actual apparatus.
[0010]
Embodiment.
10 Fig. 1 is a vertical sectional view of the hermetic compressor according to
Embodiment of the present invention. A hermetic compressor 1 includes a hermetic
container 10, a compression mechanism 20 configured to compress refrigerant, and
an electric motor 30 configured to drive the compression mechanism 20. The
compression mechanism 20 and the electric motor 30 are contained in the hermetic
15 container 10. The compression mechanism 20 is located at a lower part of the
hermetic container 10. The electric motor 30 is located at an upper part of the
hermetic container 10.
[0011]
Examples of the electric motor 30 include a DC motor. The electric motor 30
20 includes a stator 31 and a rotor 32. The stator 31 is fixed to the inner peripheral
surface of the hermetic container 10. The rotor 32 is disposed on an inner side of
the stator 31. The stator 31 is supplied with electric power from a terminal (not
illustrated) fixed to the hermetic container 10.
[0012]
25 The compression mechanism 20 includes a cylinder 21, a frame 22, a cylinder
head 23, a crankshaft 24, and a rolling piston 25. The cylinder 21 is a hollow
cylindrical component and both axial ends of the cylinder 21 are open. The frame 22
is provided at an end of the cylinder 21 that is located away from an installation
surface for the hermetic compressor 1 out of the two axial ends of the cylinder 21.
30 That is, the frame 22 is provided at an upper end of the cylinder 21 in Fig. 1. The
6
frame 22 has a T-shape in cross section and its disc part closes the opening of the
cylinder 21. The cylinder head 23 is provided at an end of the cylinder 21 that is
located closer to the installation surface for the hermetic compressor 1 out of the two
axial ends of the cylinder 21. That is, the cylinder head 23 is provided at a lower end
of the cylinder 21 in Fig. 1. The cylinder head 23 has a T-shape in 5 cross section and
its disc part closes the opening of the cylinder 21. The crankshaft 24 is inserted
through the cylinder 21, the frame 22, and the cylinder head 23. The crankshaft 24
is rotated by a driving force of the rotor 32 of the electric motor 30. The rolling piston
25 is fitted to an eccentric shaft of the crankshaft 24 and eccentrically rotates along
10 the inner peripheral surface of the cylinder 21. The inner peripheral surface of the
cylinder 21 and the outer peripheral surface of the rolling piston 25 define a
compression chamber 26.
[0013]
The hermetic compressor 1 includes a suction pipe 12, a gas/liquid separator
15 13, and a discharge pipe 14. The suction pipe 12 is connected to an evaporator (not
illustrated) of a refrigeration cycle having the hermetic compressor 1 as a component.
Refrigerant flowing out of the evaporator flows into the gas/liquid separator 13 via the
suction pipe 12 and is guided to the cylinder 21 from the gas/liquid separator 13.
The discharge pipe 14 is connected to a condenser (not illustrated) of the refrigeration
20 cycle having the hermetic compressor 1 as a component. High-pressure refrigerant
in the hermetic container 10 is sent to the refrigeration cycle via the discharge pipe
14.
[0014]
Refrigerating machine oil 11 is stored at the bottom of the hermetic container
25 10. The refrigerating machine oil 11 is guided to the compression mechanism 20 via
the crankshaft 24 by an oil supply mechanism (not illustrated) to lubricate the
respective parts of the compression mechanism 20.
[0015]
The hermetic container 10 is fixed to support bases 15 while being
30 perpendicular to the installation surface. For example, the hermetic compressor 1 is
7
generally installed on a horizontal surface on the ground. That is, the hermetic
container 10 is generally fixed and installed upright.
[0016]
Fig. 2 is a plan view illustrating the compression mechanism of the hermetic
compressor according to Embodiment of the present invention. Fig. 5 2 conceptually
illustrates the structure of the compression mechanism 20. In Fig. 2, the crankshaft
24 is omitted and its axis center is represented by reference sign 24A. Further, a
subset of components is cut out and internal structures are shown. The
compression mechanism 20 includes a vane 27, a spring 28, and a housing 29.
10 Examples of the spring 28 include a compression coil spring. The vane 27 is a thin
rectangular plate. The vane 27 is provided in a radial slit 21A of the cylinder 21 to
slide in a radial direction. An end 26A of the vane 27 in the cylinder 21 abuts against
the outer peripheral surface of the rolling piston 25 to slide along the rolling piston 25.
The vane 27 partitions the compression chamber 26 into a high-pressure area and a
15 low-pressure area and isolates the high-pressure area from the low-pressure area.
[0017]
The housing 29 is a cylindrical component and is fixed to the barrel of the
hermetic container 10 as illustrated in Fig. 1. The housing 29 houses the spring 28.
A first end 29A, which is one of the two ends of the housing 29, is located outside the
20 hermetic container 10. A second end 29B, which is the other one of the two ends of
the housing 29, is located inside a cylindrical part of the cylinder 21. That is, the
housing 29 is disposed so that the second end 29B is located near the axis center
24A of the crankshaft 24 and an axis center of the housing 29 runs in the radial
direction of the cylinder 21. The spring 28 applies an urging force to the vane 27 in
25 the radial direction toward the axis center 24A of the crankshaft 24.
[0018]
Fig. 3 is a diagram illustrating the structure of the housing according to
Embodiment of the present invention. The first end 29A has a bottom part 291.
The first end 29A is closed by the bottom part 291. The second end 29B is open.
30 The housing 29 communicates with the compression chamber 26 via the second end
8
29B and the slit 21A. The inner diameter of the housing 29 is larger than the outer
diameter of the spring 28. An end turn of the spring 28 is in contact with the bottom
part 291. The bottom part 291 has an annular groove 292. The center of the
groove 292 agrees with an axis center 29C of the housing 29. The outer diameter of
the groove 292 is larger than the diameter of the end turn of the 5 spring 28. The
width of the groove 292 is larger than the wire diameter of the spring 28. An end
turn opposite to the axis center 24A of the crankshaft 24 out of the end turns at both
ends of the spring 28 is disposed in the groove 292.
[0019]
10 Further, the housing 29 has a brittle portion 293. The brittle portion 293 is a
thin portion that is thinner than the other portion of the bottom part 291 along the axis
center 29C of the housing 29 because of the groove 292. As described above, the
second end 29B is located near the axis center 24A of the crankshaft 24 and the
housing 29 runs in the radial direction of the cylinder 21. That is, the brittle portion
15 293 is a thin portion that is thinner than the other portion of the bottom part 291 in a
direction from the axis center 24A of the crankshaft 24 to the outside of the hermetic
container 10. Thus, the strength of the brittle portion 293 against an external force
from the axis center 24A of the crankshaft 24 to the outside of the cylinder 21 in the
radial direction of the cylinder 21 is lower than the strength of the other portion of the
20 bottom part 291. Note that the thickness of the brittle portion 293 along the axis
center 29C of the housing 29 is determined based on a target pressure limit value of
the hermetic container 10.
[0020]
As described above, the first end 29A of the housing 29 is located outside the
25 hermetic container 10. That is, the housing 29 is positioned so that the length from
the axis center 24A of the crankshaft 24 to the brittle portion 293 of the housing 29 in
the radial direction of the cylinder 21 is not smaller than the length from the axis
center 24A to the outer peripheral surface of the hermetic container 10 in the radial
direction of the cylinder 21.
30 [0021]
9
Now, an operation of the hermetic compressor 1 is described. Refrigerant gas
is sucked into the cylinder 21 via the gas/liquid separator 13 through the suction pipe
12 connected to the evaporator on a low-pressure side of the refrigeration cycle.
The sucked refrigerant gas is compressed in the compression chamber 26 by the
rolling piston 25 that eccentrically moves by rotation of an eccentric 5 part of the
crankshaft 24. Thus, low-pressure and low-temperature suction gas is compressed
into high-pressure and high-temperature discharge gas. The high-temperature
discharge gas is discharged inside the hermetic container 10 and is sent to the
condenser of the refrigeration cycle through the discharge pipe 14.
10 [0022]
The refrigerating machine oil 11 stored at the bottom of the hermetic container
10 is supplied into the compression chamber 26 via the inside of the rolling piston 25
in a centrifugal direction under the assumption that the installation surface for the
hermetic compressor 1 is a bottom surface. The refrigerating machine oil 11 is
15 mixed with the high-pressure refrigerant gas in the compression chamber 26 and is
discharged inside the hermetic container 10 in the form of mist.
[0023]
If air enters a suction side of the refrigeration cycle from the outside of the
refrigeration cycle due to, for example, failure in pipe connection during construction
20 of the refrigeration cycle or damage to a low-pressure-side pipe after an operation of
the refrigeration cycle, the air is sucked and compressed in the compression chamber
26. If the air is compressed and the refrigerating machine oil 11 is present in the
form of mist at a predetermined concentration, combustion and abnormal pressure
increase at an extremely high rate may occur depending on the concentration and an
25 ambient temperature condition.
[0024]
When those phenomena occur in the compression chamber 26, the gas in the
compression chamber 26 abruptly expands at an extremely high rate. At this time,
the bottom part 291 of the housing 29 that houses the spring 28 has the brittle portion
30 293 described above. Therefore, when a pressure field at a pressure equal to or
10
higher than a design pressure of the hermetic container is generated in the
compression chamber 26, the brittle portion 293 of the housing 29 is ruptured with
precedence because of the low rigidity of the brittle portion 293.
[0025]
Advantageous effects of Embodiment are described. When 5 the gas in the
compression chamber 26 abruptly expands at an extremely high rate because air is
sucked into the compression chamber 26 as described above, the abruptly expanding
combustion gas cannot be released through a discharge passage along which normal
refrigerant gas is discharged. Therefore, the pressure in the compression chamber
10 26 abnormally increases and a portion having the lowest strength in the compression
mechanism 20 is damaged. According to Embodiment, on the other hand, the
bottom part 291 of the housing 29 is ruptured with precedence over the other
components of the compression mechanism 20 because of the low rigidity of the
brittle portion 293 of the bottom part 291. Thus, when the gas in the compression
15 chamber 26 abruptly expands at an extremely high rate, the high-pressure space in
the hermetic container 10 no longer has hermeticity and the pressure increase can be
prevented.
[0026]
Further, the housing 29 houses the spring 28. In addition, as described
20 above, the spring 28 is a component that implements the compression mechanism by
causing the vane 27 to follow eccentric rotation of the rolling piston 25 so that the lowpressure
area and the high-pressure area in the compression chamber 26 are
isolated from each other. Through the rupture of the brittle portion 293 of the
housing 29, the bottom part 291 in contact with the end turn of the spring 28 opposite
25 to the axis center 24A of the crankshaft 24 is partially or entirely lost. Thus, the end
turn of the spring 28 opposite to the axis center 24A of the crankshaft 24 loses the
support surface and the spring function is lost. The urging force of the spring 28 is
no longer applied to the vane 27. Therefore, the function of the vane 27 that isolates
the low-pressure area and the high-pressure area in the compression chamber 26 is
30 lost. Along with the loss of the urging force of the spring 28, the vane 27 no longer
11
follows the eccentric rotation. Thus, the pressure increase in the hermetic container
10 can be prevented without control.
[0027]
As described above, when a pressure abnormality occurs at a certain level in
the compression mechanism 20, the brittle portion 293 of the housing 5 29 is ruptured
and the compression mechanism 20 no longer has hermeticity. Therefore, pressure
increase is prevented. In addition, the function of the vane 27 that isolates the lowpressure
area and the high-pressure area in the compression chamber 26 of the
compression mechanism 20 is lost along with the loss of the urging force of the spring
10 28. Thus, the compression function of the hermetic compressor 1 can be halted in
the event of abnormal pressure increase in the hermetic container 10.
[0028]
Note that, in Embodiment, the first end 29A of the housing 29 is located outside
the hermetic container 10, the bottom part 291 and the brittle portion 293 are located
15 outside the hermetic container 10, and therefore the housing 29 protrudes from the
hermetic container 10, but the housing 29 is not limited to this type of housing. For
example, the housing 29 may be positioned so that the outer peripheral surface of the
bottom part 291 is flush with the outer peripheral surface of the hermetic container 10.
Reference Signs List
20 [0029]
1 hermetic compressor 10 hermetic container 11 refrigerating machine
oil 12 suction pipe 13 gas/liquid separator 14 discharge pipe 15 support
base 20 compression mechanism 21 cylinder 22 frame 23 cylinder head
24 crankshaft 24A axis center 25 rolling piston 26 compression chamber
25 26A end 27 vane 28 spring 29 housing 29A first end 29B second
end 29C axis center 30 electric motor 31 stator 32 rotor 291 bottom
part 292 groove 293 brittle portion
12
We Claim :
[Claim 1]
A hermetic compressor, comprising a hermetic container, a compression
mechanism contained in the hermetic container and configured to compress
refrigerant, and an electric motor contained in the hermetic container 5 and configured
to drive the compression mechanism,
the compression mechanism comprising a hollow cylinder, a crankshaft to be
rotated by the electric motor, a rolling piston fitted to an eccentric shaft of the
crankshaft and configured to eccentrically rotate along an inner peripheral surface of
10 the cylinder, a vane that partitions a compression chamber for the refrigerant into a
high-pressure area and a low-pressure area, the compression chamber being defined
by the inner peripheral surface of the cylinder and an outer peripheral surface of the
rolling piston, and a spring that urges the vane against the outer peripheral surface of
the rolling piston so that the vane follows eccentric rotation of the rolling piston,
15 wherein the hermetic compressor comprises a housing provided to a barrel of
the hermetic container and housing the spring,
wherein the housing comprises a brittle portion, which is lower than the
hermetic container in terms of a strength against an external force from an axis center
of the crankshaft to an outside of the hermetic container, and the housing
20 communicates with the compression chamber, and
wherein the housing is positioned so that a length from the axis center of the
crankshaft to the brittle portion in a radial direction of the cylinder is not smaller than a
length from the axis center of the crankshaft to an outer peripheral surface of the
hermetic container in the radial direction of the cylinder.
25 [Claim 2]
The hermetic compressor of claim 1,
wherein the housing is a cylindrical component,
wherein one end out of two ends of the housing has a bottom part and is
closed by the bottom part, and an other end out of the two ends of the housing is
30 open,
wherein the housing is disposed so that the other end is located near t
center of the crankshaft and an axis center of the housing runs in the radial direction
of the cylinder, and
wherein the brittle portion is formed by an annular groove in the bottom part.
5 [Claim 3]
The hermetic compressor of claim 2, wherein an e
disposed in the groove.