WO2012001989A1

WO2012001989A1 - Rotary compressor

Info

Publication number: WO2012001989A1
Application number: PCT/JP2011/003773
Authority: WO
Inventors: 大輔船越; 洋杉浦; 孝正先本; 飯田　登
Original assignee: パナソニック株式会社
Priority date: 2010-07-02
Filing date: 2011-07-01
Publication date: 2012-01-05
Also published as: EP2589810A4; JP4928016B2; EP2589810B1; CN102483066A; EP2589810A1; JPWO2012001989A1; CN102483066B

Abstract

Disclosed is a rotary compressor wherein a second area surrounded by a lower internal surface corner portion formed in the bottom surface of a piston (32) and an end plate (35) blocking the bottom surface of a cylinder (30) is larger than a first area surrounded by an upper internal surface corner portion formed in the top surface of the piston (32) and an end plate (34) blocking the top surface of the cylinder (30); and the angle between the bottom surface of the piston (32) and the lower internal surface corner portion is smaller than the angle between the top surface of the piston (32) and the upper internal surface corner portion. Thus, oil can be reliably retained on the bottom surface of the piston (32) to improve the reliability, and the piston (32) can float even when a tolerance area is increased. Therefore, the efficiency and the productivity of the rotary compressor can be improved.

Description

Rotary compressor

The present invention relates to a rotary compressor used in devices such as an air conditioner, a refrigeration device, a blower device, and a hot water supply device.

Conventionally, devices such as an air conditioner use a rotary compressor that sucks in gas refrigerant evaporated by an evaporator and compresses the sucked gas refrigerant. A rotary compressor is known as one of such rotary compressors (see, for example, Patent Document 1).

FIG. 15 is a cross-sectional view of an essential part showing an example of a rotary compressor.
In the sealed container 1, the electric motor 2 and the compression mechanism unit 3 are connected and stored by a crankshaft 31. An oil reservoir 6 is formed at the bottom of the sealed container 1. The compression mechanism unit 3 includes a cylinder 30 that forms a cylindrical internal space, a piston 32 that is disposed in the internal space of the cylinder 30, an end plate 34 of an upper bearing 34 a that closes the upper end surface of the cylinder 30, and the cylinder 30. The end plate 35 of the lower bearing 35a that closes the lower end surface of the lower bearing 35 and the vane 33 that partitions the inside of the compression chamber 39 into a low-pressure part and a high-pressure part.
The compression chamber 39 is formed by the internal space of the cylinder 30, the piston 32, the end plate 34, and the end plate 35. The crankshaft 31 is supported by an upper bearing 34a and a lower bearing 35a. An eccentric portion 31 a is formed on the crankshaft 31. The eccentric portion 31 a is disposed between the end plate 34 and the end plate 35. The piston 32 is fitted to the eccentric portion 31a. The vane 33 reciprocates in a slot provided in the cylinder 30. The tip of the vane 33 is in pressure contact with the outer periphery of the piston 32, and the vane 33 reciprocates following the eccentric rotation of the piston 32 to partition the inside of the compression chamber 39 into a low pressure portion and a high pressure portion.
An oil hole 41 is provided in the axial portion of the crankshaft 31. Oil (lubricating oil) in the oil reservoir 6 is supplied to the oil hole 41. In addition,

oil supply holes

42 and 43 communicating with the oil hole 41 are provided in the wall portion of the crankshaft 31. The oil supply hole 42 is formed in a wall portion corresponding to the upper bearing 34a, and the oil supply hole 43 is formed in a wall portion corresponding to the lower bearing 35a. Further, an oil supply hole (not shown) communicating with the oil hole 41 and an oil groove (not shown) are formed in the wall portion of the eccentric portion 31a.

On the other hand, the cylinder 30 is formed with a suction port 40 for sucking low-pressure gas. The suction port 40 communicates with a low pressure portion (suction chamber) in the compression chamber 39. A discharge port 38 for discharging the high-pressure gas compressed in the compression chamber 39 is formed in the upper bearing 34a. The discharge port 38 communicates with a high pressure portion in the compression chamber 39. The discharge port 38 is formed as a circular hole passing through the upper bearing 34a in plan view. A discharge valve 36 is provided on the upper surface of the discharge port 38. The discharge valve 36 is released when it receives a pressure of a predetermined magnitude or more. The discharge valve 36 is covered with a cup muffler 37.
The low pressure portion (suction chamber) of the compression chamber 39 gradually expands after the sliding contact portion between the piston 32 and the cylinder 30 passes through the suction port 40 and sucks gas from the suction port 40. On the other hand, in the high-pressure portion of the compression chamber 39, when the sliding portion between the piston 32 and the cylinder 30 approaches the discharge port 38 and is gradually reduced and compressed to a predetermined pressure or higher, the discharge valve 36 opens and the discharge port 38 is opened. Out of gas. The gas flowing out from the discharge port 38 is discharged into the sealed container 1 through the cup muffler 37.

On the other hand, an upper piston inner space is formed by the eccentric portion 31a of the crankshaft 31, the end plate 34 of the upper bearing 34a, and the inner peripheral surface of the piston 32. 35 and the inner peripheral surface of the piston 32 form a lower piston inner space. Oil in the oil hole 41 leaks from the oil supply hole 42 to the upper space in the piston, and oil in the oil hole 41 leaks from the oil supply hole 43 to the lower space in the piston. The upper space in the piston and the lower space in the piston are almost always higher than the pressure in the compression chamber 39.

Further, the height of the cylinder 30 must be set slightly larger than the height of the piston 32 so that the piston 32 can slide inside. As a result, the upper and lower end surfaces of the piston 32, the end plate 34, the end A gap is generated between the plate 35 and the plate 35. Therefore, oil leaks into the compression chamber 39 from the upper space in the piston and the lower space in the piston through this gap. In order to achieve high efficiency, it is necessary to maintain reliability while suppressing this leakage.

Here, a method of suppressing oil leakage from the piston upper space and the piston lower space to the compression chamber 39 will be described with reference to FIGS.
10 to 14 show a state in which the crankshaft 31 is removed for the sake of simplicity of explanation, and the gap between the piston 32 and the upper and lower end plates 34 and 35 (represented by exaggerating the vertical direction, actually It is a schematic diagram showing the relationship of several tens of μm.
As shown in FIG. 10, chamfers having substantially the same size at the upper end portion and the lower end portion are provided at the end portion of the inner peripheral surface of the piston 32.
If the chamfering of the upper end portion and the lower end portion of the inner peripheral surface of the piston 32 is the same, the piston 32 slides with the lower end plate 35 due to its own weight. Therefore, a gap of about several tens of μm is formed between the upper end face of the piston 32 and the upper end plate 34, and oil leaks into the compression chamber 39 through the gap.

In the first high efficiency method, as shown in FIG. 11, the upper and lower chamfering difference of the piston 32 is set to BA> 0.
Then, when an upward force is generated by providing a chamfering difference (BA> 0) that balances the weight of the piston 32, the piston 32 floats.
In general, since gas leakage is proportional to the cube of the gap, when the upper and lower gaps of the piston 32 are evenly distributed and when they are unevenly distributed, the latter increases as the amount of gas leakage. Therefore, gas and oil leaking into the suction chamber through the gap between the upper and lower end surfaces of the piston 32 are suppressed, and the efficiency is improved.

In the second high efficiency method, as shown in FIG. 12, the space between the piston 32 and the upper and

lower end plates

34 and 35 is reduced to about several μm.
By reducing the gap, leakage can be suppressed and efficiency can be improved.
However, since the piston 32 behaves unstable during actual operation, problems such as specular wear and seizure are likely to occur particularly on the lower end plate 35 by reducing the gap.
Therefore, as shown in FIG. 13, the chamfering of the lower end portion of the piston 32 is increased, the oil holding area between the piston 32 and the lower end plate 35 is increased, and the cooling effect by the oil is enhanced to increase the reliability. It is necessary to improve.
However, if only the lower chamfer of the piston 32 is increased, an upward force is generated due to the pressure difference, and the upper end plate 34 slides strongly.
Therefore, as shown in FIG. 14, it is necessary to increase the chamfer on both the upper and lower sides of the piston 32 so as not to generate a large upward force on the piston 32.

JP-A-8-61276

However, there are two problems in the measures for improving the efficiency and reliability of the rotary compressor.
The first problem is that when adjusting the vertical chamfering difference so as to balance the weight of the piston 32 as shown in FIG. It is very difficult to manage the dimensions.
The second problem is that when the upper and lower gaps of the piston 32 are reduced, both the upper and lower chamfers of the piston 32 need to be increased. However, as shown in Patent Document 1, the inner surface of the piston 32 and the discharge port 38 are If the seal length is not secured, the efficiency of the return of the high-pressure gas to the suction will be reduced, so that the upper side surface cannot be made so large. In the end, only the lower side chamfer of the same size as the upper side chamfer can be set, so that the reliability cannot be greatly increased.
However, if the chamfering of the upper end portion of the piston 32 is increased, the discharge port 38 and the inner surface of the piston 32 communicate with each other, so that the high-pressure gas returns to suction and the efficiency is lowered. Therefore, since it is necessary to secure the seal length between the inner surface of the piston 32 and the discharge port 38, only the lower chamfer having the same size as the upper chamfer can be set, and the reliability cannot be greatly increased.

The present invention solves such problems, and improves productivity, improves leakage by suppressing leakage of the upper and lower end faces of the piston, and improves reliability by suppressing wear and seizure of the end plate. It is for the purpose.

In order to achieve the above object, the present invention provides a cylinder, an eccentric part of a shaft disposed in the cylinder, a piston fitted in the eccentric part, and following the eccentric rotation of the piston. A rotary compressor having a vane that reciprocates in a slot provided in the slot, and two end plates that close the upper and lower end surfaces of the cylinder, and a lower inner corner formed on the lower end surface of the piston, A second area surrounded by the end plate closing the lower end surface of the cylinder is surrounded by an upper inner surface corner formed on the upper end surface of the piston and the end plate closing the upper end surface of the cylinder. The angle between the lower end surface of the piston and the lower inner surface corner is smaller than the angle between the upper end surface of the piston and the upper inner surface corner.

According to the above configuration, since the pressure drop when oil flows from the lower inner surface corner to the compression chamber at the lower end surface of the piston becomes large, even if the second area by the lower inner surface corner is increased, it is large upward. No power is generated. Therefore, the amount of oil retained between the lower end surface of the piston and the end plate that closes the lower end surface of the cylinder is increased, and the seal length between the piston and the discharge port can be secured. Efficiency can be realized. In addition, the tolerance range of the area surrounded by the upper and lower inner corners of the piston and the upper and lower end plates can be set large so as to balance with the piston's own weight, so that mass productivity is improved and efficiency is improved.

The longitudinal cross-sectional view of the rotary compressor in Embodiment 1 of this invention Enlarged sectional view of the compression mechanism of the rotary compressor Cross section of piston of the same rotary compressor The figure which shows the distribution of the pressure applied to the top and bottom of the piston of the rotary compressor Schematic diagram showing the positional relationship between the clearance between the piston and the upper and lower end plates and the discharge port when the upper and lower clearances of the piston of the rotary compressor are reduced. Schematic diagram showing the positional relationship between the clearance between the piston and the upper and lower end plates and the discharge port when a force that balances the weight of the piston of the rotary compressor is generated Sectional drawing which shows the piston of the rotary compressor in Embodiment 1 of this invention Rotating diagram of rotary compressor with different configuration Further swirl diagram of rotary compressor with different configuration Schematic diagram showing the positional relationship between the clearance and the discharge port between the piston and the upper and lower end plates of a general rotary compressor Schematic diagram showing the positional relationship between the clearance between the piston and the upper and lower end plates and the discharge port when a force that balances the weight of the piston of a general rotary compressor is generated Schematic diagram showing the positional relationship between the clearance between the piston and the upper and lower end plates and the discharge port when the upper and lower clearance of the piston of a general rotary compressor is reduced Schematic diagram showing the positional relationship between the discharge port and the clearance between the piston and the upper and lower end plates when the lower chamfer of the piston of a general rotary compressor is increased Schematic diagram showing the positional relationship between the discharge port and the clearance between the piston and the upper and lower end plates when the upper and lower chamfers of the piston of a general rotary compressor are increased Cross section of a conventional rotary compressor

DESCRIPTION OF SYMBOLS 1 Airtight container 2 Electric motor 3 Compression mechanism part 22 Stator 24 Rotor 30 Cylinder 31 Crankshaft 31a Eccentric part 32 Piston 33 Vane 34a Upper bearing 34 End plate 35a Lower bearing 35 End plate 36 Discharge valve 37 Cup muffler
38 discharge port 39 compression chamber 40 suction port 41 oil hole 42 oil supply hole 43 oil supply hole 44 oil supply hole 45 oil groove 46 space 47 space

According to a first aspect of the present invention, there is provided an upper inner surface corner portion formed on the upper end surface of the piston, and a second area surrounded by a lower inner surface corner portion formed on the lower end surface of the piston and an end plate closing the lower end surface of the cylinder. The angle between the lower end surface of the piston and the lower inner surface corner is made larger than the first area surrounded by the end plate closing the upper end surface of the cylinder, and the angle between the upper end surface of the piston and the upper inner surface corner It is a smaller one.
With this configuration, the pressure drop when oil flows from the piston inner surface to the compression chamber increases at the lower end surface of the piston. Therefore, even if the second area due to the lower inner surface corner of the piston is increased, the piston is large upward. No power is generated. Therefore, even if the upper and lower gaps of the piston are reduced to increase efficiency, the amount of oil retained in the lower end plate can be increased, and the gap between the upper inner corner of the piston and the discharge port can be increased. Since the seal length can be secured, high reliability can be maintained.

In the second aspect of the invention, in particular, in the rotary compressor of the first aspect of the invention, the upper inner corner is formed by chamfering and the lower inner corner is formed by counterbore.
With this configuration, it is possible to make an up / down determination visually when assembling, and it is possible to reduce efficiency and loss cost due to an error in the up / down direction.

According to a third aspect of the invention, in particular, in the rotary compressor of the second aspect of the invention, the angle between the upper end surface of the piston and the upper inner surface corner is in the range of 132 to 138 degrees.
With this configuration, when generating a force that balances the piston's own weight, if the upper and lower sides of the piston are chamfered, BA is about 0.1 mm, whereas if only the lower side has a counterbore shape, B -A can increase the tolerance to about 0.4 to 0.8 mm, improving the mass productivity.

In the fourth aspect of the invention, in particular, in the rotary compressors of the first to third aspects of the invention, the first area and the second area are set so as to balance the weight of the piston.
With this configuration, the piston floats, and the two gaps between the upper and lower end surfaces of the piston and the end plate are made uniform. In general, since gas leakage is proportional to the cube of the gap, when the gaps above and below the piston are evenly distributed and when they are unevenly distributed, the latter has a larger amount of gas leakage. For this reason, gas and oil leaking into the suction chamber through the gap between the upper and lower end surfaces of the piston are suppressed, so compression loss can be reduced, and it is equivalent to reducing the gap without reducing the upper and lower gaps. The efficiency is further improved, and the reliability is further improved as compared with the case where the efficiency is improved by reducing the gap.

In the fifth aspect of the invention, in particular, in the rotary compressors of the first to fourth aspects of the invention, by using CO ₂ as a high-pressure refrigerant as the working fluid, the differential pressure is particularly large, and sliding loss and leakage loss are large. Even CO ₂ can be more effectively increased in efficiency.

In a sixth aspect of the invention, in particular, in the rotary compressors of the first to fifth aspects of the present invention, a single refrigerant comprising a refrigerant having a base component of a hydrofluoroolefin having a double bond between carbon and carbon as the working refrigerant, or A mixed refrigerant containing a refrigerant is used as a working refrigerant.
This refrigerant has the property of being easily decomposed at high temperatures, but by reducing leakage loss and sliding loss, it is possible to improve the reliability of the compressor more effectively while suppressing high temperature decomposition of the refrigerant. Become. Moreover, since this refrigerant has no ozone destruction and a low global warming potential, it can contribute to the configuration of an air-conditioning cycle that is friendly to the earth.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a rotary compressor according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged view of the compression mechanism section. In addition, about the structural member demonstrated using FIG. 15, the same code | symbol is attached | subjected and description is abbreviate | omitted.
An oil supply hole 44 communicating with the oil hole 41 and an oil groove 45 are formed in the wall portion of the eccentric portion 31 a of the crankshaft 31.
On the other hand, the piston inner upper space 46 is formed by the eccentric portion 31a of the crankshaft 31, the end plate 34 of the upper bearing 34a, and the inner peripheral surface of the piston 32, and the ends of the eccentric portion 31a of the crankshaft 31 and the lower bearing 35a. A piston inner lower space 47 is formed by the plate 35 and the inner peripheral surface of the piston 32. Oil in the oil hole 41 leaks from the oil supply hole 42 into the piston upper space 46, and oil in the oil hole 41 leaks from the oil supply hole 43 into the piston lower space 47. The piston upper space 46 and the piston lower space 47 are almost always higher than the pressure inside the compression chamber 39.
Further, the height of the cylinder 30 must be set slightly larger than the height of the piston 32 so that the piston 32 can slide inside. As a result, the end surface of the piston 32 and the end plate of the upper bearing 34a. 34, and between the end face of the piston 32 and the end plate 35 of the lower bearing 35a. Therefore, oil leaks from the upper piston inner space 46 and the lower piston inner space 47 to the compression chamber 39 through the gap.

About the rotary compressor comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.
As shown in FIG. 3, in the first embodiment, an upper inner surface that forms a second area 32 b surrounded by a lower inner surface corner portion and an end plate 35 formed on the lower end surface of the piston 32 on the upper end surface of the piston 32. The area is larger than the first area 32 a surrounded by the corners and the end plate 34.
In the first embodiment, the angle D between the lower end surface of the piston 32 and the lower inner surface corner is made smaller than the angle C between the upper end surface of the piston 32 and the upper inner surface corner.
The first embodiment is configured as described above to improve efficiency and reliability.

FIG. 4 shows the pressure distribution applied to the piston 32 in the first embodiment.
As shown in FIG. 4, on the upper side of the piston 32, the high pressure is uniformly distributed on the inner surface side, and the end surface side is linearly distributed from the high pressure to the intermediate pressure.
On the other hand, on the lower side of the piston 32, the high pressure is uniformly distributed on the inner surface side, but the end surface side is linearly distributed from the medium high pressure (pressure lower than the high pressure) to the intermediate pressure. That is, since the angle D between the lower end surface of the piston 32 and the lower inner surface corner is smaller than the angle C on the lower side of the piston 32, the oil flow becomes worse and a pressure drop occurs. Therefore, as shown in FIG. 5, even if the width of B on the lower side of the piston 32 is increased, so much force is not generated upward.
Accordingly, the amount of oil retained by the lower end plate 35 is increased, and the seal length L between the piston 32 and the discharge port 38 can be secured, so that high reliability and high efficiency can be realized. Further, by setting A and B so as to balance with the own weight of the piston 32, as shown in FIG. 6, even if the upper and lower gaps are reduced even if the piston 32 floats and the upper and lower gaps are not reduced. An effect is obtained.
(Embodiment 2)

FIG. 7 is a cross-sectional view showing a piston of a rotary compressor according to Embodiment 2 of the present invention. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
As shown in FIG. 7, in the second embodiment of the present invention, a second area 32 b surrounded by a lower inner surface corner formed on the lower end surface of the piston 32 and the end plate 35 is formed on the upper end surface of the piston 32. It is made larger than the first area 32 a surrounded by the upper inner corner and the end plate 34.
In the second embodiment, the angle D between the lower end surface of the piston 32 and the lower inner surface corner is made smaller than the angle C between the upper end surface of the piston 32 and the upper inner surface corner.
In the present embodiment, the upper inner surface corner portion is formed by chamfering the upper end surface and the upper inner surface of the piston 32, and the lower inner surface corner portion is formed by counterboring the lower end surface and the lower inner surface of the piston 32.
The angle C between the upper end surface of the piston 32 and the upper inner corner is preferably in the range of 132 degrees to 138 degrees, and more preferably 135 degrees.
By making the lower inner corner portion of the piston 32 counterbore, the angle D between the lower end surface of the piston 32 and the lower inner corner portion is 90 degrees.
In the present embodiment, the upper inner corner is formed by chamfering and the lower inner corner is formed by counterbore, so that it is possible to determine whether the piston 32 is up or down visually during assembly. Can be reduced. In addition, when generating a force that balances the weight of the piston 32, when the upper and lower sides of the piston 32 are chamfered, the BA is about 0.1 mm, whereas if only the lower side is a counterbore, the BA is The tolerance range can be expanded to about 0.4 to 0.8 mm, which improves mass productivity.

FIG. 8 shows a rotary compressor having a configuration different from that of the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the structure same as Embodiment 1, and description is abbreviate | omitted.
The rotary compressor shown in FIG. 8 is connected to the outer peripheral portion of the piston 132 in a protruding manner, and partitions the compression chamber 39 into a low pressure side and a high pressure side, and the vane 133 is swingable and retractable. The swing bush 130 is supported.
Also in the rotary compressor shown in FIG. 8, the configurations of the first embodiment and the second embodiment can be applied, and an equivalent effect can be obtained.

FIG. 9 shows a rotary compressor having a further different configuration. In addition, the same code | symbol is attached | subjected to the structure same as Embodiment 1, and description is abbreviate | omitted.
The rotary compressor shown in FIG. 9 includes a piston 232 and a vane 233 that is swingably connected at the tip.
Also in the rotary compressor shown in FIG. 9, the configurations of the first embodiment and the second embodiment can be applied, and an equivalent effect can be obtained.

Further, by using CO ₂ as the working fluid, fluid leakage at the upper and lower end surfaces of the piston 32 can be reduced, and even in the case of CO ₂ where the differential pressure is large and the influence of leakage loss and sliding loss is large, the piston 32 can be reduced. Since it is possible to avoid the force that strongly presses down, it is possible to increase the efficiency more effectively. In addition, when a single refrigerant composed of a refrigerant based on a hydrofluoroolefin having a double bond between carbon and carbon as a working fluid or a mixed refrigerant containing the refrigerant is used as a working refrigerant as a working fluid, the characteristics peculiar to this kind of refrigerant. The problem of the state can be suppressed. That is, this refrigerant is easily decomposed at high temperatures and is unstable. However, in the rotary compressor of the present invention, the lubricity of the sliding portion between the end face of the piston 32 and the end plate 35 is improved, so that the temperature rise at the sliding portion can be efficiently suppressed, and the refrigerant can be decomposed. And the reliability can be improved more effectively.

Note that a mixed refrigerant in which the hydrofluoroolefin is tetrafluoropropene (HFO1234yf or HFO1234ze) or trifluoropropene (HFO1243zf) and the hydrofluorocarbon is difluoromethane (HFC32) may be used as the working refrigerant.
Alternatively, a mixed refrigerant in which the hydrofluoroolefin is tetrafluoropropene (HFO1234yf or HFO1234ze) or trifluoropropene (HFO1243zf) and the hydrofluorocarbon is pentafluoroethane (HFC125) may be used as the working refrigerant.
Also, a three-component mixed refrigerant in which the hydrofluoroolefin is tetrafluoropropene (HFO1234yf or HFO1234ze) or trifluoropropene (HFO1243zf) and the hydrofluorocarbon is pentafluoroethane (HFC125) and difluoromethane (HFC32) is the working refrigerant. It is good.

In the above embodiment, a single-piston rotary compressor with one cylinder has been described as an example. However, a rotary compressor such as a rotary compressor having a plurality of cylinders may be used.

As described above, the rotary compressor according to the present invention suppresses deterioration of reliability such as wear and seizure, and simultaneously reduces leakage loss and sliding loss, thereby improving the efficiency of the compressor. It becomes possible. Thereby, in addition to the compressor for an air conditioner using an HFC-type refrigerant or an HCFC-type refrigerant, the present invention can be applied to an application such as an air conditioner using a natural refrigerant CO ₂ or a heat pump type hot water heater.

Claims

A cylinder, an eccentric part of a shaft disposed in the cylinder, a piston fitted to the eccentric part, and a vane reciprocating in a slot provided in the cylinder following the eccentric rotation of the piston. A rotary compressor having two end plates for closing the upper and lower end surfaces of the cylinder, a lower inner surface corner portion formed on the lower end surface of the piston, and the end plate for closing the lower end surface of the cylinder; A second area surrounded by an upper inner surface corner formed on the upper end surface of the piston and a first area surrounded by the end plate closing the upper end surface of the cylinder, and The rotary compressor characterized in that the angle between the lower end surface of the piston and the lower inner surface corner is smaller than the angle between the upper end surface of the piston and the upper inner surface corner.
2. The rotary compressor according to claim 1, wherein the upper inner surface corner is formed by chamfering and the lower inner surface corner is formed by counterbore.
3. The rotary compressor according to claim 2, wherein an angle between the upper end surface of the piston and a corner portion of the upper inner surface is in a range of 132 degrees to 138 degrees.
The rotary compressor according to any one of claims 1 to 3, wherein the first area and the second area are set so as to balance the weight of the piston.
The rotary compressor according to any one of claims 1 to 4, wherein CO 2 that is a high-pressure refrigerant is used as the working fluid.
6. The working fluid is a single refrigerant composed of a refrigerant composed of carbon and a hydrofluoroolefin having a double bond between carbons as a base component or a mixed refrigerant containing the refrigerant. A rotary compressor according to any one of the above.