JP2002257047A - Relief valve for compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relief valve for a compressor that certainly operates without air-tight leakage even when the valve is used in a high pressure state. SOLUTION: Refrigerant in a delivery chamber passes through a connecting passage 26, goes from a throttle hole 34 in a throttle member 35 into an oil sump chamber 31, and contacts with a valve element 32 via a passage 29. Lubricating oil contained in the refrigerant is gradually reserved in the oil reserving chamber 31, the oil that has come into the oil sump chamber 31 is suppressed from returning to the connecting passage 26 even in internal pressure variation due to the existence of the throttle member 35, and the oil in the oil sump chamber 31 always soaks a contact part between the valve element 32 and the passage 29. Thus, high sealing function is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve for a compressor, and more particularly to a relief valve suitable for use in a high pressure state.

[0002]

2. Description of the Related Art In general, in a piston type compressor such as a swash plate type compressor, a suction chamber and a discharge chamber are defined in a housing with a partition wall therebetween, and are opposed to the suction chamber and the discharge chamber. The cylinder is arranged with the valve plate interposed therebetween. A piston is slidably disposed in a cylinder bore of the cylinder, and refrigerant in the suction chamber is sucked into the cylinder and discharged from the cylinder into the discharge chamber according to the reciprocating motion of the piston. For this reason, during operation of the compressor, the discharge chamber is in a high pressure state and the suction chamber is in a low pressure state, but when the pressure in the discharge chamber exceeds a predetermined value and becomes abnormally high, a relief valve is used for the purpose of reducing the pressure. For example, Japanese Patent Application Laid-Open No. 9-60588
No. 1993. The relief valve usually has a structure in which a valve element biased by a spring is housed in a case, and when the gas pressure increases, the valve element is opened by pushing the valve element against the urging force of the spring. It is supposed to.

[0003]

By providing such a relief valve, it is possible to maintain the safety by reducing the abnormally high gas pressure. For example, when carbon dioxide is used as the refrigerant, However, since it is used at a considerably high pressure, there is a risk of airtight leakage from the relief valve.

An object of the present invention is to provide a relief valve for a compressor which operates reliably without airtight leakage even when used under high pressure. .

[0005]

SUMMARY OF THE INVENTION A relief valve for a compressor according to the present invention defines a valve body accommodating chamber and an oil sump chamber which are communicated with each other through a passage in a casing, and is provided in the valve body accommodating chamber. The movably housed valve body is pressed by a biasing means at a predetermined pressure to close the passage, and a restrictor for preventing oil in the oil sump chamber from flowing out to the refrigerant flow path is provided in the oil sump chamber and the compressor. And the refrigerant distribution channel. Lubricating oil contained in the refrigerant passes through the throttle and accumulates in the oil sump chamber with the circulation of the refrigerant, and the oil improves the sealing performance between the passage and the valve element. The oil in the oil sump chamber is prevented from flowing out into the circulation path of the refrigerant due to the presence of the throttle. In addition, if the valve body is formed of metal, the sealing performance is further improved.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a swash plate type variable displacement compressor provided with a relief valve according to an embodiment of the present invention. The front housing 1 and the rear housing 2 are fastened by bolts 4 with the gasket 3 interposed therebetween, thereby forming the entire housing 5. A step 6 is formed in the front housing 1, and a retainer forming plate 7, a valve forming plate 8, a valve plate 9, and a valve forming plate 10 are fitted so as to be joined to the step 6. Retainer forming plate 7
The suction chamber 12 and the discharge chamber 13 are defined between the front housing 1 and the front end wall 11 of the front housing 1 with a partition wall 14 therebetween.

A cylinder 15 is fitted into the front housing 1 so as to be joined to the valve forming plate 10, and is fixed to the front housing 1 by bolts 16.
A rotary shaft 17 is rotatably supported by the cylinder 15, the front housing 1 and the rear housing 2. The front end of the rotating shaft 17 protrudes from the front housing 1 to the outside, and is connected to a rotary drive source (not shown) such as an engine or a motor of the vehicle. In the rear housing 2, a rotation support 18 is fixed to a rotation shaft 17 and a swash plate 19 is attached so as to engage with the rotation support 18.
The swash plate 19 has a rotating shaft 1 in a through hole formed in the center thereof.
When the swash plate 19 penetrates, a guide pin 20 protruding from the swash plate 19 is slidably fitted into a guide hole 21 formed in the rotary support 18, and the guide pin 20 and the guide hole 21 are linked. The rotating shaft 17 is supported integrally with the rotating shaft 17 so as to be slidable and tiltable in the axial direction. The rotary support 18 is rotatably supported by a thrust bearing 22 disposed on the inner wall of the rear end of the rear housing 2.

[0008] A plurality of cylinder bores 23 are formed in the cylinder 15 around a rotation shaft 17.
A piston 24 is slidably accommodated in 3. Each piston 24 is engaged with the outer peripheral portion of the swash plate 19 via a shoe 25, and when the swash plate 19 rotates together with the rotation shaft 17, each piston 24 moves inside the cylinder bore 23 through the shoe 25 to rotate the rotation shaft 17. Reciprocates in the axial direction.

In the lower part of the front housing 1, a discharge chamber 1 is provided.
3 and a relief valve 27 communicated via a communication path 26
Is attached. As shown in FIG. 2, the relief valve 27 has a casing 28,
Inside the valve body housing chamber 30 communicated with each other through the passage 29.
And an oil sump chamber 31 are defined. Valve housing chamber 30
A valve body 32 made of metal is slidably housed therein, and a spring 33 for pressing the valve body 32 toward the passage 29 with a predetermined pressure is provided. Spring 33
Forms the urging means of the present invention. Normally, the valve body 32 is pressed by the urging force of the spring 33 and the passage 29 is closed. On the other hand, the oil sump chamber 31 facing the communication path 26
A stop member 35 having a stop hole 34 opened in the center is fixed to the end of the stop member. Such a relief valve 27 is screwed to a lower portion of the front housing 1 via an O-ring 36.

Next, the operation of the relief valve according to this embodiment will be described. By the reciprocating operation of the piston 24, that is, the operation of retreating in the cylinder bore 23, the refrigerant in the suction chamber 12 flows from the suction port of the valve plate 9 into the cylinder bore 23 by displacing the suction lead of the valve forming plate 10, and the subsequent piston By the forward movement of 24, that is, the operation of moving forward in the cylinder bore 23, the discharge port of the valve plate 9 is pushed out of the discharge lead portion of the valve forming plate 8 and discharged into the discharge chamber 13.

The refrigerant in the discharge chamber 13 reaches the relief valve 27 through the communication path 26,
4 enters the oil sump chamber 31 and comes into contact with the valve body 32 via the passage 29. The refrigerant contains lubricating oil, and this oil is gradually stored in the oil storage chamber 31. In particular, in this embodiment, since the relief valve 27 is arranged at the lower part of the front housing 1, the lubricating oil easily flows down the communication path 26 and is introduced into the oil sump chamber 31. Once the oil has entered the oil sump chamber 31, the throttle member 3
Due to the presence of 5, even if there is an internal pressure fluctuation or the like, the return to the communication path 26 is suppressed, and the contact portion between the valve element 32 and the passage 29 is constantly immersed in the oil in the oil reservoir chamber 31.
For this reason, even if the valve body 32 is made of metal, high sealing performance is ensured.

Since the inside of the discharge chamber 13 becomes high-pressure due to the reciprocating operation of the piston 24, the high-pressure refrigerant presses the valve body 32 in a direction to compress the spring 33. Is set to be larger, and usually does not open. However, for some reason, the pressure of the refrigerant in the discharge chamber 13 becomes abnormally high,
When the pressing force of the refrigerant becomes larger than the urging force of the spring 33, the valve body 32 slides against the urging force of the spring 33 and opens. As a result, the high-pressure refrigerant is discharged from the oil storage chamber 31 to the atmosphere through the passage 29 and the valve body housing chamber 30, and the pressure in the discharge chamber 13 is reduced.

The relief valve 27 according to this embodiment
Has a high sealing property, so that even when the refrigerant is used in a considerably high pressure state because carbon dioxide is used as the refrigerant, airtight leakage from the relief valve 27 is prevented. In a conventional relief valve, a rubber material having flexibility was used as a valve body.However, carbon dioxide has a property of easily penetrating the rubber material and has a high adiabatic index. Then, it becomes easy to cause airtight leakage. In this regard, in this embodiment, the metal valve element 32
, The sealing performance is ensured even when carbon dioxide is used as the refrigerant. In addition, the valve body 32 can be formed with resin etc. other than metal.

In the above-described embodiment, the throttle member 35 is disposed at the base end of the casing 28 of the relief valve 27. However, the present invention is not limited to this. For example, as shown in FIG. The base end of the casing 38 is opened and the communication path 2 of the front housing 1 is opened.
A throttle 39 may be formed in the middle of 6, and an oil reservoir 40 may be formed between the throttle 39 and the relief valve 37.

[0015]

As described above, according to the present invention, the valve body accommodating chamber and the oil sump chamber which are communicated with each other through the passage in the casing are defined, and can be moved into the valve body accommodating chamber. The accommodated valve body is pressed by the urging means at a predetermined pressure to close the passage, and a restrictor for preventing the oil in the oil sump chamber from flowing out to the refrigerant flow path is provided with a throttle for the refrigerant in the oil sump chamber and the compressor. The lubricating oil contained in the refrigerant passes through the throttle and is stored in the oil sump chamber, and the oil improves the sealing property between the passage and the valve element. That is, even when used in a high-pressure state, the operation can be reliably performed without airtight leakage. If the valve body is formed of metal, it becomes a particularly useful compressor relief valve when carbon dioxide is used as a refrigerant.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a configuration of a swash plate type variable displacement compressor provided with a relief valve according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a configuration of the relief valve of FIG.

FIG. 3 is a side sectional view showing a configuration of a relief valve according to another embodiment.

[Explanation of symbols]

26 communication path, 27, 37 relief valve, 28, 3
8 casing, 29 passages, 30 valve body accommodation chamber, 31,
40 oil sump chamber, 32 valve body, 33 spring, 34 throttle hole, 35 throttle member, 36 O-ring, 39 throttle.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshiro Fujii 2-1-1 Toyota-cho, Kariya-shi, Aichi F-term in Toyota Industries Corporation (reference) 3H003 AA03 AB07 AC03 AD01 BC00 CC02 CD05

Claims (2)

[Claims] 1. A relief valve connected to a flow path of a refrigerant containing lubricating oil in a compressor, wherein the casing defines a valve housing chamber and an oil sump chamber communicated with each other via a passage. A valve body movably housed in a valve body housing chamber of the casing; a biasing unit that presses the valve body with a predetermined pressure to close the passage; and a flow of refrigerant in the oil sump chamber and the compressor. A relief valve disposed between the oil reservoir and the oil sump chamber to prevent the oil in the oil sump chamber from flowing out to the refrigerant circulation path. 2. The relief valve for a compressor according to claim 1, wherein the valve body is formed of a metal.