JPH0461266B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an expansion valve for controlling the amount of refrigerant supplied to an evaporator of a refrigeration system.

(Prior art and its problems) Conventionally, the above-mentioned expansion valve has been disclosed in, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 144875, high-pressure refrigerant leaks into the chamber (operating space) below the diaphragm from between the sliding contact surface between the outer circumferential surface of the large diameter part of the operating rod and the inner circumferential surface of the passage. In order to prevent this, a sealing member is provided at the large diameter portion. However, in the case where a sealing member is provided in this way, the sealing function deteriorates due to wear of the sealing member over time, and the high-pressure refrigerant flows to the lower side of the diaphragm. As a result, so-called heating degree control, which detects the temperature and pressure at the evaporator outlet and controls the amount of refrigerant flowing into the evaporator, cannot be performed accurately. Moreover, in devices equipped with a sealing member, if the frictional force between the sealing member and the inner circumferential surface of the passage is increased in order to improve the sealing performance, the sliding performance of the operating rod deteriorates, and conversely, when trying to improve the sliding performance, The sealing performance deteriorates, and it is extremely difficult to set the frictional force between the sealing member and the inner circumferential surface of the passage so as to satisfy both. Furthermore, the tapered valve seat (seat part) of the valve body, which opens and closes between the high pressure chamber (passage) and the low pressure chamber (valve chamber), forms an acute angle valve seat (seat part) between the high pressure chamber and the low pressure chamber. At the time of contact, since the outer diameter of the portion of the valve body located inside the low-pressure chamber is larger than the diameter of the acute-angled valve seat, when the regulating valve body is opened, the regulating valve body is influenced by the high-pressure refrigerant and moves in the opening direction. If the lift exceeds a predetermined value, more refrigerant will flow from the high pressure chamber to the low pressure chamber, and the degree of heating of the refrigerant at the outlet of the evaporator will become smaller than necessary.

(Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to prevent high-pressure refrigerant from flowing into the working space on the working rod side of the diaphragm without providing a sealing member, and to maintain the heating level for a long period of time. The first object is to provide an expansion valve that can be accurately controlled. Furthermore, the present invention provides an expansion valve in which the regulating valve body does not move more than a predetermined lift in the valve opening direction due to the influence of high-pressure refrigerant when the valve is opened, and the degree of heating of the refrigerant at the outlet of the evaporator does not become smaller than necessary. The third purpose is to

(Means for Solving the Problems) In order to solve the above-mentioned problems, the first aspect of the present invention is to provide an expansion valve for controlling the amount of refrigerant supplied to the evaporator of a refrigeration system. a high-pressure chamber connected to a pipe and into which a high-temperature, high-pressure refrigerant flows; a low-pressure chamber, which is connected to the inlet-side pipe of the evaporator and into which a low-temperature, low-pressure refrigerant flows;
an operating rod fitting chamber, an operating rod slidably fitted in the operating rod fitting chamber, and the high pressure chamber and low pressure chamber provided at one end of the operating rod so as to be able to operate integrally therewith. and a regulating valve body which adjusts the passage opening area between the valve body and which is biased in the valve closing direction by a spring, and which is provided at the other end of the actuating rod and adjusts the actuating valve body according to the difference in pressure acting on both end faces. a pressure-responsive member that is displaced in the axial direction of the rod, and a refrigerant passage chamber that is located on the reaction rod side of the pressure-responsive member and through which refrigerant passes on the way from the outlet of the evaporator to the suction port of the compressor. and,
an operating space that is provided opposite to the end surface on the operating rod side of the pressure responsive member and communicates with the refrigerant passage chamber; and an operating space that is provided on the end surface of the reaction rod side of the pressure responsive member and is responsive to temperature changes in the refrigerant passage chamber. pressure generating means for generating pressure to press the operating rod in the valve opening direction via the pressure-responsive member; and a refrigerant in the high pressure chamber sliding between the outer circumferential surface of the operating rod and the inner circumferential surface of the operating rod fitting chamber. The refrigerant refrigerant is configured to include a leak means for leaking the leaked refrigerant to the refrigerant passage chamber when the refrigerant leaks between the surfaces. The second aspect of the present invention is an expansion valve for controlling the amount of refrigerant supplied to an evaporator of a refrigeration system, which is connected to a conduit on the discharge port side of a compressor and has a high-pressure chamber into which high-temperature and high-pressure refrigerant flows. , a low-pressure chamber connected to the high-pressure chamber and the inlet side pipe of the evaporator, and into which a low-temperature, low-pressure refrigerant flows;
an acute-angled seat portion provided at the periphery of a passage connecting the low pressure chamber and the high pressure chamber and having a smaller diameter than the inner diameter of the low pressure chamber; an operating rod fitting chamber; an operating rod located within the low pressure chamber and provided at one end of the operating rod so as to be able to operate integrally therewith, the tapered seat portion of which moves toward and away from the acute-angled seat portion of the passage, thereby reducing the high pressure. A truncated cone-shaped adjustment valve body that adjusts the passage opening area between the chamber and the low pressure chamber and is biased in the valve closing direction by a spring, and a truncated conical adjustment valve body that is provided at the other end of the operating rod and is displaced on both end faces. a pressure-responsive member in the axial direction of the working rod, and a pressure-responsive member located on the reaction rod side of the pressure-responsive member, and extending from the outlet of the evaporator to the inlet of the compressor. a refrigerant passage chamber through which the refrigerant passes, a working space provided opposite to the end surface of the pressure responsive member on the operating rod side and communicating with the refrigerant passage chamber, and an end surface of the pressure responsive member on the reaction rod side. pressure generating means for generating pressure to press the operating rod in the valve opening direction via the pressure responsive member in response to a temperature change in the refrigerant passage chamber; The outer diameter of the portion located closer to the low pressure chamber than the contacting portion is set to a value as close as possible to the diameter of the acute-angled sheet portion.

(Example) Hereinafter, one example of the present invention will be described based on the drawings. The figure is a block diagram of a refrigeration system incorporating the expansion valve of the present invention. In the figure, 1 indicates the entire expansion valve of the present invention, and the expansion valve 1 is installed in a housing 2 at one end (lower end in the figure). The expansion valve main body 4 is inserted through the provided insertion port 3 through a plurality of (three in this embodiment) O-rings (sealing members) 5 ₁ , 5 ₂ , 5 _{3 ,} and the closure member 6 closes the insertion port 3 . The expansion valve main body 4 is fixed within the housing 2 by airtightly closing the expansion valve main body 4.

The housing 2 is formed by die-casting using an aluminum material, but may be formed by cold forging or hot forging. The housing 2
has a hollow cylindrical shape with one end (lower end in the figure) open and the other end (upper end in the figure) closed, and the inner hole thereof serves as the expansion valve main body insertion chamber 7. A first connection port 8 is provided at a substantially intermediate portion in the axial direction of one side peripheral wall of the housing 2 so as to penetrate in the radial direction. A second connection port 9 is provided at one end (on the insertion port 3 side) of the other circumferential wall of the housing 2 from a substantially intermediate portion in the axial direction, passing through the housing 2 in the radial direction. A third connection port 10 is provided on the other end side (the side opposite to the insertion port 3) of the other peripheral wall of the housing 2 so as to penetrate in the radial direction. A fourth connection port 11 is provided at the other end of one peripheral wall of the housing 2 so as to face the third connection port 10 and penetrate in the radial direction.

The expansion valve main body 4 has a casing 12 radially fitted into the expansion valve main body insertion chamber 7 of the housing 2, and a stepped portion 12a at one end (lower end in the figure) of the casing 12 is inserted into the insertion opening 3 of the housing 2. It abuts on the stepped portion 3a and has a gap 7a serving as a refrigerant passage chamber between the other end (upper end in the figure) and the inner end of the insertion chamber 7 of the housing 2;
The third and fourth connection ports 1 are provided in the refrigerant passage chamber 7a.
0 and 11 are open. The casing 12 has a hollow cylindrical shape with both end faces open, and its inner circumferential face extends from one end ( The lower end in the figure) has a larger diameter than the other end (the upper end in the figure). A small diameter portion inside the casing 12 serves as an operating rod fitting chamber 14, and an operating rod 15 is slidably fitted into the operating rod fitting chamber 14. The operating rod 15 has a stepped portion 1 located approximately in the middle in the axial direction.
6, one end side (lower end side in the figure) has a larger diameter than the other end side (upper end side in the figure), and the outer circumferential surface of the large diameter portion 15a slides on the inner circumferential surface of the operating rod fitting chamber 14. The diameter is fitted freely. A regulating valve body 17 is attached to one end of the operating rod 15 so as to be able to operate integrally therewith. The adjusting valve body 17 is a tapered seat that approaches and separates from an acute-angled seat portion 19 provided at the periphery of a passage 18 that is located on the inner peripheral side of the stepped portion 13 and connects with the operating rod fitting chamber 14. It has a truncated conical shape with a portion 20. In the valve closed state in which the tapered seat portion 20 of the regulating valve body 17 contacts the acute-angled seat portion 19 of the passage 18, the operating rod fitting chamber 1
A high pressure chamber 21 is defined between the stepped portion 16 of the operating rod 15 in the valve body 4 and the end portion of the regulating valve body 17 on the tapered seat portion 20 side (upper end side in the figure). The adjusting valve body 17 is urged toward the valve closing side (upper side in the figure) by a spring 22, and the spring 22 is screwed into the inner circumferential surface of the adjusting valve body 17 and one end side of the large diameter portion of the casing 12. The spring receiving member 23 is interposed between the spring receiving member 23 and the spring receiving member 23 . A low pressure chamber 24 is defined between the step portion 13 and the spring receiving member 23 within the large diameter portion of the casing 12 . A first through hole 25 and a second through hole 26, which open into the high pressure chamber 21 and the low pressure chamber 24, respectively, are provided through the peripheral wall of the casing 12 in the radial direction.
Note that the first through hole 25 and the second through hole 26 are provided on both sides of the casing 12, and the second through hole on one side is
The through hole 26 is connected to the first connection port 8, and the first through hole 25 on the other side is connected to the first connection port 8.
are in communication with the second connection port 9, respectively.

A first through hole 2 is provided on the outer peripheral surface of the casing 12.
Annular grooves 27 ₁ , 27 2 , _and 27 ₃ are provided at one end side of the groove 5, between the first through hole 25 and the second through hole 26, and on the other end side of the second through hole 26, respectively. ,
The O-rings 5 ₁ , 5 ₂ , 5 ₃ are fitted into these annular grooves 27 ₁ , 27 ₂ , 27 ₃ , respectively, and these O-rings 5 ₁ to 5 ₃ connect the inner peripheral surface of the insertion chamber 7 of the housing 2 and the casing. A high-pressure side and a low-pressure side between the outer circumferential surface of 12 are airtightly partitioned.

A diaphragm (pressure responsive member) 28 is provided within the recess provided at the other end of the casing 12. The outer periphery of the diaphragm 28 is held between the outer periphery of the inner bottom wall of the recess at the other end of the casing 12 and the outer periphery of the plate 29.
9 and the diaphragm 28 has a gap 29a. The center portion of the diaphragm 28 is in contact with the other end surface of the operating rod 15 (the end surface on the side opposite to the regulating valve body 17), and is displaced in the axial direction of the operating rod 15. An operating space 30 is provided between the end surface of the diaphragm 28 on the operating rod 15 side and the inner bottom wall of the recess of the casing 12.
A third through hole 31 provided along the radial direction in the peripheral wall of No. 2
(external pressure equalization passage) and the gap 32 between the outer circumferential surface of the casing 12 and the inner circumferential surface of the expansion valve body insertion chamber 7 in the housing 2. It communicates with the inside of the side end of the insertion port 3, that is, the inside of the refrigerant passage chamber 7a.

A pressure generating means 33 is provided at the other end of the casing 12, facing the diaphragm 28. The pressure generating means 33 is a closed space 34a formed by attaching a substantially hemispherical cover 34 to the end of the plate 29 opposite to the diaphragm 28, and a gas that expands in proportion to the temperature is sealed in the closed space 34a. Inside is a through hole 36 bored in the plate 29.
It communicates with the inside of the gap 29a between the diaphragm 28 and the plate 29 via. Said cover 3
4, the temperature of the refrigerant passing through the refrigerant passage chamber 7a is transmitted into the closed space 34a, and in response to the temperature, pressure is generated to press the operating rod in the valve opening direction through the diaphragm 28. It's summery.

The closing member 6 is made of a threaded member and is screwed onto the inner circumferential surface of the insertion port 3, and the space between the closing member 6 and the casing 12 is airtightly sealed with an O-ring 37. It is fitted into an annular groove 38 on the inner end surface of the closing member 6.

When the refrigerant in the high pressure chamber 21 leaks between the sliding surfaces of the outer peripheral surface of the large diameter portion 15a of the operating rod 15 and the inner peripheral surface of the operating rod fitting chamber 14, the leaked refrigerant is transferred to the refrigerant passage chamber 7a. A leak means is provided for causing the leak. The leak means is the large diameter portion 1 of the operating rod 15.
An annular leak groove 39 provided on the outer peripheral surface of 5a,
The annular leak groove 39 and the refrigerant passage chamber 7a are connected to each other by a leak passage 40 which is provided through the circumferential wall of the casing 12 in the radial direction. It communicates with the inside of the refrigerant passage chamber 7a via a gap 32 between the insertion chamber 7 and the inner circumferential surface of the insertion chamber 7. Note that the leak passage 40 and the third through hole 31 are connected to the casing 12.
is displaced by 180° in the circumferential direction, thereby preventing the refrigerant from the leak passage 40 from directly flowing into the third through hole 31.

Outer diameter D of the portion of the regulating valve body 17 that is located closer to the low pressure chamber 24 than the portion that contacts the acute-angled seat portion 19
is set to a value as close as possible to the diameter D ₁ of the acute-angled seat portion 19.

The expansion valve 1 of the present invention configured as described above has the following features:
The first connection port 8 is connected to the discharge port 43a of the compressor 43 through the receiver tank 41 and the condenser 42,
The fourth connection port 11 is connected to the suction port 43b of the compressor 43,
The second connection port 9 is connected to the inlet 44a of the evaporator 44, and the third
It is incorporated into a refrigeration system by connecting the connection ports 10 to the outlets 44b of the evaporator 44, respectively.

(Operation) Next, the operation of the expansion valve 1 having the above configuration will be explained.
The high-temperature, high-pressure refrigerant compressed by the drive of the compressor 43 flows through the condenser 42 → receiver tank 41 → second through hole 26 → high pressure chamber 21 → low pressure chamber 24 → first through hole 25
→ Evaporator 44 → Returns to compressor 43 again via the path of refrigerant passage chamber 7a. In such a refrigeration cycle, the temperature of the refrigerant flowing out from the outlet of the evaporator 44 is detected by the cover 34 in the refrigerant passage chamber 7a, and the sealed gas in the closed space 34a expands (contracts) according to the temperature. , the operating rod 15 descends (rises) in the valve opening (valve closing) direction via the diaphragm 28.
let The pressure in the sealed space is determined by the refrigerant temperature in the refrigerant passage chamber 7a, and the opening degree of the regulating valve body 17 is determined by the balance between this pressure and the spring force of the spring 22, and the opening degree of the regulating valve body 17 is determined according to the opening degree. The amount of refrigerant flowing into the low pressure chamber 24 from the high pressure chamber 21 is determined, and accordingly, the amount of refrigerant flowing into the evaporator 44 is determined. That is, the pressing force of the diaphragm 28 in the valve opening direction
F _D is the refrigerant pressure and temperature in the refrigerant passage chamber _7a through which the refrigerant from the outlet of the evaporator 44 passes.
T ₁ , the pressure inside the sealed space 34a is P ₂ , and the pressure receiving area of the diaphragm 28 is A, then F _D =(P ₂ −
P ₁ )・A. Here, P ₂ is the pressure determined corresponding to T ₁ , and if the spring force of the spring 22 is Fsp, then F _D
=Fsp=( _P2 - _P1 )・A, and since _P2 is a function of _T1 , by appropriately selecting Fsp and pressure change characteristics with respect to _T1 in the closed space 34a,
The difference between the saturation temperature corresponding to P ₁ and T ₁ , i.e. the evaporator 4
The degree of heating of the outlet refrigerant in step 4 can be controlled within an appropriate range.

When the expansion valve 1 is operated, the outer diameter D of the regulating valve body 17 is set to a value as close as possible to the diameter _D1 of the acute-angled seat portion 19, so that it is not affected by the high-pressure refrigerant when the valve is opened. Therefore, the opening degree (throttling amount) of the regulating valve body 17 does not become smaller than a predetermined value. Furthermore, the high-pressure refrigerant in the high-pressure chamber 21 is connected to the outer circumferential surface of the large diameter portion 15a of the operating rod 15 and the operating rod fitting chamber 14.
If the refrigerant leaks between the sliding surface and the inner peripheral surface of the refrigerant, the leaked refrigerant accumulates in the annular leak groove 39 and then leaks into the refrigerant passage chamber 7a through the leak passage 40 and the gap 32. Therefore, the leaked refrigerant flows into the working space 30.
As a result, the pressure in the working space 30 increases and the diaphragm 28 is displaced more than a predetermined amount in the valve closing direction, so that the opening degree (throttling amount) of the regulating valve body 17 does not fall below a predetermined value. Furthermore, there is no problem of excessive heating of the refrigerant at the outlet of the evaporator 44 due to insufficient flow rate.

Furthermore, when maintaining, inspecting, servicing, etc. the expansion valve body 4, it is sufficient to remove the closing member 6 from the insertion port 3 and pull out the expansion valve body 4 from the insertion port 3 of the housing 2. Since the connection parts to devices such as the evaporator 44 can remain connected, maintenance is easy, and the refrigerant temperature in the refrigerant passage chamber 7a at the inner end of the expansion valve body insertion chamber 7 of the housing 2 can be directly measured. Since it is a sensing method, there are no restrictions on installation location.

Note that in the above embodiment, the annular leak groove 39
Although the case has been described in which it is provided on the outer circumferential surface of the large diameter portion 15a of the operating rod 15, the present invention is not limited to this, and it may be provided on the inner circumferential surface of the operating rod fitting chamber 14.

(Effects of the Invention) As described above, the first aspect of the present invention is that in an expansion valve for controlling the amount of refrigerant supplied to an evaporator of a refrigeration system, the A high-pressure chamber into which refrigerant flows, a low-pressure chamber connected to the high-pressure chamber and the inlet side pipe of the evaporator and into which low-temperature, low-pressure refrigerant flows, an operating rod fitting chamber, and the operating rod fitting chamber. an operating rod fitted in a slidable manner; and an operating rod provided at one end of the operating rod so as to be able to operate integrally therewith to adjust the passage opening area between the high pressure chamber and the low pressure chamber, and a spring an adjusting valve body biased in the valve closing direction; a pressure responsive member provided at the other end of the operating rod and displacing in the axial direction of the operating rod in response to a difference in pressure acting on both end surfaces;
a refrigerant passage chamber located on the reaction rod side of the pressure responsive member and through which refrigerant passes on the way from the outlet of the evaporator to the suction port of the compressor; and an end surface of the pressure responsive member on the reaction rod side. an actuation space that is provided opposite to the refrigerant passage chamber and communicates with the refrigerant passage chamber; and an actuation space that is provided on the reaction rod side end surface of the pressure responsive member and that operates via the pressure responsive member in response to temperature changes in the refrigerant passage chamber. A pressure generating means for generating pressure to press the rod in the valve opening direction; Since the refrigerant is provided with a leak means for causing the refrigerant to leak into the refrigerant passage chamber, the high-pressure refrigerant can be prevented from flowing into the working space on the working rod side of the diaphragm without providing a sealing member, and the heating degree can be controlled accurately over a long period of time. This has the effect that it can be done.

The second aspect of the present invention is that in an expansion valve for controlling the amount of refrigerant supplied to an evaporator of a refrigeration system, a high-pressure chamber is connected to a conduit on the discharge port side of a compressor and into which high-temperature and high-pressure refrigerant flows. is connected to the high pressure chamber and the inlet side pipe of the evaporator, respectively, and is connected to the low temperature and
a low pressure chamber into which a low pressure refrigerant flows; an acute-angled seat portion provided at the periphery of a passage connecting the low pressure chamber and the high pressure chamber and having a smaller diameter than the inner diameter of the low pressure chamber; an operating rod fitting chamber; and the operating rod fitting. an operating rod that is slidably fitted into the chamber; and an operating rod that is located within the low-pressure chamber and is provided at one end of the operating rod so as to be able to operate integrally therewith, and that the tapered seat portion forms an acute-angled seat of the passage. a truncated conical regulating valve body which adjusts the passage opening area between the high pressure chamber and the low pressure chamber by moving toward and away from the section, and which is biased in the valve closing direction by a spring; a pressure-responsive member disposed at one end of the evaporator and displaceable in the axial direction of the working rod in response to a difference in pressure acting on both end faces; a refrigerant passage chamber through which the refrigerant passes on the way from the outlet to the suction port of the compressor; an operating space that is provided opposite to the end surface of the pressure responsive member on the operating rod side and communicates with the refrigerant passage chamber; pressure generating means, which is provided on the end surface of the responsive member on the reaction rod side and generates a pressure that presses the operating rod in the valve opening direction via the pressure responsive member in response to a temperature change in the refrigerant passage chamber;
Since the outer diameter of the part of the regulating valve element located closer to the low pressure chamber than the part that contacts the acute-angled seat part is set to a value as close as possible to the diameter of the acute-angled seat part, when the regulating valve element opens, high-pressure refrigerant Since the degree of superheating of the refrigerant at the outlet of the evaporator does not become smaller than necessary, this effect is achieved.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the expansion valve of the present invention installed in a refrigeration system. DESCRIPTION OF SYMBOLS 1... Expansion valve, 2... Housing, 3... Insertion port, 4... Expansion valve body, 5 ₁ to 5 ₃ ... O-ring (sealing member), 6... Closing member, 7... Expansion valve main body Insertion chamber, 7a... Refrigerant passage chamber, 8... First connection port, 9... Second connection port, 10... Third connection port, 1
1...Fourth connection port, 14...Operation rod fitting chamber, 15
... Operating rod, 17 ... Adjustment valve body, 18 ... Passage,
19...Acute angle sheet portion, 20...Tapered sheet portion, 21...High pressure chamber, 22...Spring, 24...Low pressure chamber, 25...First passage hole, 26... Second passage hole, 2
8...Diaphragm (pressure responsive member), 30...
Working space, 31... third through hole (external pressure equalization passage),
33... Pressure generating means, 39... Annular leak groove,
40...Leak passage.

Claims (1)

[Scope of Claims] 1. In an expansion valve for controlling the amount of refrigerant supplied to an evaporator of a refrigeration system, a high-pressure chamber connected to a conduit on the discharge port side of a compressor and into which high-temperature and high-pressure refrigerant flows; a low-pressure chamber connected to the high-pressure chamber and the inlet side pipe of the evaporator and into which a low-temperature, low-pressure refrigerant flows; an operating rod fitting chamber; and a low-pressure chamber that is slidably fitted into the operating rod fitting chamber. An operating rod, which is provided at one end of the operating rod so as to be able to operate integrally therewith, adjusts the passage opening area between the high pressure chamber and the low pressure chamber, and is biased by a spring in the valve closing direction. an adjusting valve body, a pressure-responsive member provided at the other end of the operating rod and displaced in the axial direction of the operating rod in accordance with a difference in pressure acting on both end surfaces; a refrigerant passage chamber, which is provided oppositely to the end surface of the operating rod side of the pressure responsive member, through which the refrigerant passes on the way from the outlet of the evaporator to the suction port of the compressor; The actuating space communicates with the chamber, and the pressure-responsive member is provided on the end face of the reaction rod side, and applies pressure to press the actuating rod in the valve-opening direction via the pressure-responsive member in response to temperature changes in the refrigerant passage chamber. and a leak means for leaking the leaked refrigerant to the refrigerant passage chamber when the refrigerant in the high pressure chamber leaks between the sliding surfaces of the outer peripheral surface of the operating rod and the peripheral surface of the operating rod fitting chamber. An expansion valve comprising: 2 The refrigerant passage chamber side open end of the communication portion that communicates the refrigerant passage chamber and the working space and the refrigerant passage chamber side open end of the leak passage are displaced approximately 180° from each other in the circumferential direction of the working rod. The expansion valve according to claim 1, characterized in that: 3. The expansion valve according to claim 1, wherein the pressure responsive member is a diaphragm. 4. The leak means comprises an annular leak groove provided on the outer circumferential surface of the operating rod, and a leak passage communicating the annular leak groove with the refrigerant passage chamber. expansion valve. 5. Claims characterized in that the leak means comprises an annular leak groove provided on the inner circumferential surface of the operating rod fitting chamber, and a leak passage communicating the annular leak groove with the refrigerant passage chamber. The expansion valve according to item 1. 6 In an expansion valve for controlling the amount of refrigerant supplied to the evaporator of a refrigeration system, a high-pressure chamber connected to the discharge port side pipe of the compressor and into which high-temperature/high-pressure refrigerant flows, and the high-pressure chamber and the evaporator. a low pressure chamber connected to each of the inlet side pipes and into which low-temperature, low-pressure refrigerant flows; and an acute-angled sheet portion provided at the periphery of a passage connecting the low pressure chamber and the high pressure chamber and having a diameter smaller than the inner diameter of the low pressure chamber. an operating rod fitting chamber, an operating rod slidably fitted into the operating rod fitting chamber, and an operating rod located within the low pressure chamber and provided at one end of the operating rod so as to be able to operate integrally therewith. The tapered seat portion moves toward and away from the acute-angled seat portion of the passage to adjust the opening area of the passage between the high pressure chamber and the low pressure chamber, and the truncated portion is biased in the valve closing direction by a spring. a conical regulating valve body; a pressure-responsive member disposed at the other end of the operating rod and displaced in the axial direction of the operating rod in response to a difference in pressure acting on both end surfaces; and a reaction of the pressure-responsive member. a refrigerant passage chamber provided on the rod side and through which refrigerant passes on the way from the outlet of the evaporator to the suction port of the compressor; and a refrigerant passage chamber provided opposite to the end surface of the pressure responsive member on the operating rod side; An operating space communicating with the refrigerant passage chamber and an end surface of the pressure responsive member on the reaction rod side are provided, and the actuating rod is pressed in the valve opening direction via the pressure responsive member in response to a temperature change in the refrigerant passage chamber. and pressure generating means for generating a pressure such that the outer diameter of a portion of the regulating valve body located closer to the low pressure chamber than the portion that contacts the acute-angled seat portion is set to a value as close as possible to the diameter of the acute-angled seat portion. An expansion valve characterized by setting. 7. The expansion valve according to claim 6, wherein the pressure responsive member is a diaphragm.