JP2004257471A - Pressure relief valve of refrigeration cycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure relief valve to be used for the refrigeration cycle with CO<SB>2</SB>gas as refrigerant which is capable of enhancing sealability and close contact of the valve when the valve is re-closed after the pressure is released. <P>SOLUTION: The pressure relief valve of the refrigeration cycle is double-sealed by a first seal part S1 and a second seal part S2. The first seal part S1 can obtain metal seal by a valve seat 5 and a valve element 8, and the seal part is not chemically degraded with CO<SB>2</SB>gas. The second seal part S2 can obtain seal by elastic close contact with fluororubber 16 or 20. Sealability is enhanced thereby. When the valve is re-closed after the pressure is released, sealability can be ensured even when a small gas leak is formed from the first seal part S1 by the elastic close contact of the fluororubber 16 or 20 of the second seal part. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pressure relief valve for a refrigeration cycle using CO ₂ gas as a refrigerant.
[0002]
[Prior art]
In a refrigeration cycle of a vehicle air conditioner or the like, when the refrigerant pressure in the high-pressure side passage downstream of the compressor rises to a predetermined value or more, the gas pressure that has become abnormally high due to the opening operation of the pressure relief valve is reduced. Safety is ensured (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-8-135817 (page 2, FIG. 1)
[0004]
[Problems to be solved by the invention]
The conventional pressure relief valve has a configuration in which a rubber packing that is in close contact with the valve seat is fitted and disposed on the lower surface (opposite surface of the valve seat) of the valve body, but a refrigeration cycle using CO ₂ gas as a refrigerant. When used in a so-called supercritical refrigeration cycle in which the internal pressure of the high-pressure side path is equal to or higher than the critical pressure of the refrigerant, the refrigerant temperature downstream of the compressor (between the compressor and the gas cooler) is high (150 ° C. or higher). Therefore, a problem arises in terms of heat resistance.
[0005]
So easily when CO ₂ gas using a fluorine rubber material having heat resistance is transmitted through the rubber packing as the rubber packing, also rubber packing by CO ₂ gas is a new problem that easy sealability is deteriorated swell Occurs.
[0006]
From these facts, it is conceivable that the valve seat and the valve body are made of metal and metal-sealed.However, in this case, the adhesion when the pressure is once released and then re-closed is deteriorated, and a minute gas leak is generated. Can occur.
[0007]
Accordingly, the present invention provides a return-type pressure relief valve that can be used in a refrigeration cycle using CO ₂ gas as a refrigerant and that can improve the sealing performance and ensure the valve adhesion at the time of re-closing after pressure release. Is what you do.
[0008]
[Means for Solving the Problems]
In the pressure relief valve of the present invention, a metal valve casing having a valve seat formed at a boundary between a pressure introducing portion and an atmosphere opening portion; and a metal valve casing disposed on the atmosphere opening portion side of the valve casing and having the valve seat. A valve body that is in contact with the valve body and a spring that presses the valve body against the valve seat, the valve body being provided on a high-pressure side path downstream of a compressor of a refrigeration cycle using CO ₂ gas as a refrigerant; Is made of metal, the valve body and the valve seat are formed in a tapered first seal portion, a gap portion having a small cross-sectional area provided subsequent to the first seal portion, and A second seal portion made of a fluororubber-based material provided to bring the valve body and the valve seat into close contact with each other.
[0009]
【The invention's effect】
According to the pressure relief valve of the present invention, since the first seal portion and the second seal portion perform double sealing, even if the pressure relief valve is disposed in the high pressure side path between the discharge port of the compressor and the gas cooler, Gas leaks can be reliably prevented by enhancing the sealing performance of high-temperature, high-pressure CO ₂ gas refrigerant.
[0010]
Moreover, since the first seal portion is a metal seal in which the valve seat and the valve element are in metal contact, the sealing effect is not impaired by a chemical change due to the contact with the CO ₂ gas.
[0011]
In particular, since a void having a small cross-sectional area is formed following the first seal portion, the seating property of the valve body with respect to the valve seat in the first seal portion is stabilized, and the sealability of the first seal portion is improved. Can be enhanced.
[0012]
When the gas pressure in the high-pressure side path abnormally rises and the pressure relief valve opens, releases the pressure, and then closes again, the first seal portion makes the valve seat and the valve body contact each other. Since the valve body is in a tapered shape in contact with the valve body, self-alignment of the valve body is performed, and the valve body can be properly seated on the valve seat without being inclined, and sealing can be performed.
[0013]
Also, at the time of re-closing, even in the event that dust or the like is caught in the first seal portion and the seal becomes unstable, the sealing property is improved by the elastic adhesion of the fluoro rubber material of the second seal portion. Gas leak can be prevented.
[0014]
In addition, since the second seal portion made of the fluororubber-based material is disposed in the void having a small cross-sectional area, even if there is a small gas leak in the first seal portion, the degree of contact with the CO ₂ gas is small. , CO ₂ gas permeation and swelling of the fluororubber-based material can be avoided, so that the reuse rate of the pressure relief valve is improved and the service cost can be reduced.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
1 and 2 show a first embodiment of a pressure relief valve according to the present invention. FIG. 1 is a sectional view showing the entire pressure relief valve, and FIG. 2 is an enlarged view showing a main part of FIG.
[0017]
The pressure relief valve 1 in the first embodiment is provided immediately after a discharge port of a compressor of a refrigeration cycle (not shown) using CO ₂ gas as a refrigerant or in a high-pressure side path between the compressor and a gas cooler.
[0018]
The metal valve casing 2 is formed in a cylindrical shape provided with a pressure introducing portion 3 and an atmosphere opening portion 4, and a valve seat 5 is formed at a boundary between the pressure introducing portion 3 and the atmosphere opening portion 4. is there.
[0019]
The distal end portion of the casing provided with the pressure introducing portion 3 is formed to have a small diameter, and a screw portion 6 for screwing the high pressure side passage is formed on the outer periphery thereof, and a seal is provided at the base of the small diameter portion. Rubber packing 7 is fitted and arranged.
[0020]
The atmosphere opening portion 4 is formed to have a larger diameter than the pressure introducing portion 3, and the valve seat 5 has a tapered first sealing surface 5 a and a flat second sealing surface serving as an inner end surface of the atmosphere opening portion 4. 5b.
[0021]
A valve body 8 that contacts the valve seat 5 and a spring 9 that presses the valve body 8 against the valve seat 5 are disposed in the atmosphere opening section 4.
[0022]
A screw portion 10 is formed on the inner periphery of the opening at the outer end of the atmosphere opening portion 4, and an adjusting screw 11 having an opening 11 a formed at the center is screwed into the screw portion 10.
[0023]
The spring 9 is elastically mounted over a disc-shaped spring seat 12 abutting on the inner end face of the adjusting screw 11 and a spring seat portion 13 formed on the back of the valve body 8. The pressing force is adjusted by adjusting the screwing of.
[0024]
A label 14 made of a dust-proof resin film for closing the opening 11a is attached to the outer end surface of the adjusting screw 11.
[0025]
The valve body 8 has a tapered first sealing surface 8a that contacts the first sealing surface 5a of the valve seat 5 on a surface facing the valve seat 5 (a surface opposite to the surface on which the spring seat portion 13 is formed). And a flat second sealing surface 8b facing the second sealing surface 5b of the valve seat 5.
[0026]
The taper inclination angle of the first seal surface 5a of the valve seat 5 is formed larger than the taper inclination angle of the first seal surface 8a of the valve body 8, and the tip side (small diameter side) of these first seal surfaces 5a, 8a is formed. A first seal portion S1 is formed in which the partial seals come into contact with each other to form a seal, and a gap portion 15 having a small cross-sectional area following the first seal portion S1 is formed between the opposed surfaces of the valve seat 5 and the valve body 8. I have.
[0027]
Specifically, in the present embodiment, the gap 15 is formed between the first gap 15a formed between the tapered first seal faces 5a, 8a and the flat second seal faces 5b, 8b. And the second gap 15b.
[0028]
The second gap 15b constitutes a second seal portion S2 made of a fluororubber-based material for bringing the second seal surfaces 5b and 8b into close contact with each other.
[0029]
In the present embodiment, the second seal portion S2 is configured by providing a coating layer 16 of a fluororubber-based material on the surface of the second seal surface 8b of the valve body 8, and the coating layer 16 is formed in a tapered shape. It extends to the surface of one sealing surface 8a.
[0030]
According to the structure of the pressure relief valve 1 of the first embodiment described above, since the first seal portion S1 and the second seal portion S2 perform double sealing, the pressure relief valve 1 is disposed near the discharge port of the compressor (not shown). Even if it is, the sealing performance of the high-temperature, high-pressure CO ₂ gas refrigerant can be enhanced to reliably prevent gas leakage.
[0031]
Moreover, since the first seal portion S1 has a metal seal tapered first sealing surface 5a of the valve seat 5 and the valve body 8, mutual 8a is a metal contact, by chemical change due to contact with the CO ₂ gas The sealing effect is not impaired.
[0032]
Specifically, in the present embodiment, the coating layer 16 made of the fluoro rubber-based material constituting the second seal portion S2 is extended to the tapered first seal surface 8a of the valve body 8, but the first seal By the seating of the tapered surface between the surface 8a and the first sealing surface 5a of the valve seat 5, the coating layer 16 of the first sealing surface 8a is not exposed to the pressure introducing portion 3, and these first sealing surfaces 5a are not exposed. , 8a substantially form a metal seal, thereby avoiding the problem of chemical change due to contact with CO ₂ gas.
[0033]
Further, following the first seal portion S1 formed by the contact of the first seal surfaces 5a and 8a, the tapered first gap portion 15a of the gap portion 15 having a small cross-sectional area exists. The seating performance of the first sealing surface 8a with respect to the first sealing surface 5a in the portion S1 is stabilized, so that poor seating of the first sealing surface 8a can be avoided, and the sealing performance of the first sealing portion S1 can be improved.
[0034]
When the gas pressure in the high-pressure side path is abnormally increased and the pressure relief valve 1 is opened and the pressure is released, and then reclosed, the first seal portion S1 includes the valve seat 5 and the valve body 8. Since the first sealing surfaces 5a and 8a are tapered so as to abut each other, the valve body 8 is automatically aligned, and the valve body 5 can be properly seated without being inclined to perform sealing.
[0035]
Also, at the time of re-closing the valve, even if the first seal portion S1 is caught by dust or the like and the seal becomes unstable, the elastic seal of the fluoro rubber-based material 16 of the second seal portion S2 may cause the seal to become unstable. Gas leakage can be prevented by ensuring sealing performance.
[0036]
Moreover, since the second seal portion S2 made of the fluororubber-based material is disposed in the second gap portion 15b in the gap portion 15 having a small cross-sectional area, even if there is a minute gas leak in the first seal portion S1. , The degree of contact with the CO ₂ gas is small, so that the permeation of the CO ₂ gas and the swelling of the fluororubber-based material coating layer 16 can be avoided. Can be reduced.
[0037]
Here, particularly in the present embodiment, as described above, the second sealing portion S2 is formed by providing the coating layer 16 of a fluoro rubber-based material on the surface of the second sealing surface 8b of the valve body 8. Therefore, the second seal portion S2 can be advantageously formed in terms of cost without increasing the number of parts to be assembled and the number of assembling steps, and the thickness control of the coating layer 16 is easy and the second seal portion with high sealing accuracy is provided. The seal portion S2 can be configured.
[0038]
Further, since the coating layer 16 can be easily extended to the first sealing surface 8a as described above, the presence of the extending portion of the coating layer 16 on the first sealing surface 8a allows the pressure relief valve 1 to be extended. Even if the first seal portion S1 is caught by dust or the like at the time of re-closing of the valve, the sealing property can be maintained high by the elastic close contact action of the extended portion of the coating layer 16.
[0039]
3 and 4 show a second embodiment of the present invention. FIG. 3 is an overall sectional view of a pressure relief valve, and FIG. 4 is an enlarged view of a main part of FIG.
[0040]
In the second embodiment, the second seal surface (valve seat surface) 5b of the valve seat 5 in the first embodiment is formed in a tapered shape, and a continuous portion between the first seal surface 5a and the second seal surface 5b is formed. A small step 17 having a right angle is formed in an annular shape.
[0041]
On the other hand, the valve body 8 has a small right-angled stepped portion 18 facing the stepped portion 17 formed in an annular shape following the first sealing surface 8a, and a small-diameter portion 19 formed following the stepped portion 18. The small-diameter portion 19 and the formation end surface are used as the second sealing surface 8b.
[0042]
A small gap is set between the end faces of the steps 17 and 18 to form a first gap 15a, and a gap between the second sealing surface 8b and the tapered second sealing surface 5b is a gap 15b. .
[0043]
Then, an O-ring 20 made of a fluororubber material is mounted on the small diameter portion 19 of the valve body 8, and the second seal surfaces 5 b and 8 b of the valve seat 5 and the valve body 8 are brought into close contact with the O-ring 20. It constitutes the second seal part S2.
[0044]
According to the structure of the second embodiment, in the normal state, the tapered first sealing surfaces 5a, 8a constituting the first sealing portion S1 of the valve seat 5 and the valve body 8 are brought into direct metal contact with each other, and The tapered first sealing surfaces 5a, 8a serve as seals, and the seating stability of the tapered first sealing surfaces 5a, 8a is ensured by the presence of the first gap 15a. The second seal surface 5b is elastically adhered to the second seal surface 5b so as to bite along the taper inclination, so that a reliable seal can be obtained. Therefore, the same effect as that of the first embodiment can be obtained. Even when the valve is closed, the same valve closing and sealing properties as in the first embodiment can be obtained.
[0045]
Further, in the present embodiment, an O-ring 20 made of a fluoro rubber material is attached to the small diameter portion 19 constituting the second sealing surface 8b of the valve body 8, so that the second sealing portion S2 is constituted. The second seal portion S2 can be easily formed by the insertion of the O-ring 20, and the second seal surface 5b of the valve seat 5 is tapered, so that the O-ring can be easily tightened toward the small diameter side of the taper. It can be elastically contacted, and the sealing effect can be enhanced.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an entire structure of a first embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is a sectional view showing the entire structure of a second embodiment of the present invention.
FIG. 4 is an enlarged view of a main part of FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pressure relief valve 2 Valve casing 3 Pressure introduction part 4 Atmospheric release part 5 Valve seat 8 Valve element 9 Spring 15 Gap part 15a First gap part 15b Second gap part 16 Coating layer (fluororubber-based material)
20 O-ring (fluoro rubber-based material)
S1 first seal portion S2 second seal portion

Claims (6)

A metal valve casing (2) having a valve seat (5) formed at a boundary between the pressure introducing section (3) and the atmosphere opening section (4);
A valve body (8) arranged on the side of the valve casing (2) that is open to the atmosphere (4) and in contact with the valve seat (5);
A spring (9) for pressing the valve body (8) against the valve seat (5);
With
A pressure relief valve (1) provided in a high-pressure side passage downstream of a compressor of a refrigeration cycle using CO ₂ gas as a refrigerant,
The valve body (8) is made of metal, and the valve body (8) and the valve seat (5) have a tapered first seal portion (S1) that is in close contact with each other;
A void portion (15) having a small cross-sectional area provided following the first seal portion (S1);
A second seal portion (S2) made of a fluororubber-based material provided in the gap portion (15) to make the valve body (8) and the valve seat (5) in close contact with each other. Pressure relief valve for refrigeration cycle. A first gap portion (15a) provided immediately after the first seal portion (S1);
A second gap (15b) provided immediately after the first gap (15a),
The pressure relief valve of a refrigeration cycle according to claim 1, wherein the second seal portion (S2) is provided in the second gap portion (15b). The pressure relief of a refrigeration cycle according to claim 1 or 2, wherein the second seal portion (S2) is formed by providing a coating layer (16) of a fluororubber material on the surface of the valve body (8). valve. The pressure relief valve of a refrigeration cycle according to claim 3, wherein the coating layer (16) extends on the surface of the valve body (8) of the first seal portion (S1). The pressure of the refrigeration cycle according to claim 1 or 2, wherein the second seal portion (S2) is configured by fitting an O-ring (20) made of a fluororubber material to the valve body (8). Relief valve. The pressure relief valve of a refrigeration cycle according to claim 5, wherein the valve seat surface (5b) to which the O-ring (20) is in close contact is formed in a tapered shape.

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