JPH10259968A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of an impact sound due to a strike of a valve plug on a valve seat by specifying a diametral dimension of a rod guide hole through which a rod is inserted, in an expansion valve wherein the valve plug is urged in the direction of valve opening through the intermediary of a rod interposed below a power element which operates on sensing the temperature of a low-pressure refrigerant. SOLUTION: In an expansion valve used for a refrigerating cycle of an automobile, a power element 30 which operates on sensing the temperature of a low-pressure refrigerant is fitted to the outer opening end part of a rod guide hole 14 which is provided in projection on the extension of the axis of an exit-side passage 13b of a high-pressure refrigerant passage 13 for sending a high-temperature high-pressure refrigerant liquid expanded adiabatically into an evaporator. A rod 23 is inserted through the rod guide hole 14 so that it is movable forward and backward in the axial direction, and one end face thereof is brought into contact with the center of the lower side of a diaphragm 32 of the power element 30. In this case, the diametral dimension of the rod guide hole 14 is set in a range not exceeding the dimension obtained by adding 0.02 mm to the diametral dimension of the rod 23 and thereby a play between the rod guide hole 14 and the rod 23 is diminished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve for adiabatically expanding a refrigerant while controlling the flow rate of the refrigerant sent to an evaporator in a refrigeration cycle.

[0002]

2. Description of the Related Art There are various types of expansion valves. A valve seat is formed in the middle of a high-pressure refrigerant flow path through which a high-pressure refrigerant sent to an evaporator passes, and a valve body is arranged to face the valve seat. The valve body is urged in the valve closing direction by a spring, and a rod interposed between the power element and the power element that operates by sensing the temperature of the low-pressure refrigerant sent from the evaporator. An expansion valve in which a valve element is urged in a valve opening direction via a valve is widely used.

[0003]

In the above-described expansion valve, a rod is supported by being inserted into a rod guide hole formed in a main body block or the like between a power element and a valve body. , Such a rod guide hole,
In consideration of processing errors and the like, the diameter is formed to be 0.05 mm or more larger than the diameter of the rod.

[0004] However, if there is such a play between the rod and the rod guide hole, when the clearance between the valve body and the valve seat is narrow in a control state in which the flow rate of the refrigerant is very small, the rod is not moved. The valve body repeatedly hits the valve seat due to lateral swing or the like, and the striking sound generated at that time is noise.

Accordingly, an object of the present invention is to provide an expansion valve which does not generate a striking sound when the valve body hits the valve seat, even when the gap between the valve body and the valve seat is narrow.

[0006]

In order to achieve the above object, an expansion valve according to the present invention has a valve seat formed in the middle of a high-pressure refrigerant flow path through which a high-pressure refrigerant fed to an evaporator passes. A valve element is disposed in opposition to the valve element, and the valve element is urged in a valve closing direction by a spring, and is axially interposed between the valve element and a power element that operates by sensing the temperature of the low-pressure refrigerant sent from the evaporator. In an expansion valve in which the valve body is urged in the valve opening direction via a rod interposed in a freely movable manner, a diameter dimension of a rod guide hole through which the rod is inserted to guide the rod so as to be able to advance and retract in the axial direction. Is formed in a range not exceeding a size obtained by adding 0.02 mm to the diameter of the rod.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an expansion valve according to a first embodiment of the present invention. This expansion valve is used, for example, in a refrigeration cycle of a vehicle indoor cooling device (car air conditioner).

In the main body block 11 of the expansion valve, a high-pressure refrigerant flow path 13 for adiabatically expanding a high-temperature and high-pressure refrigerant liquid compressed by a compressor and sending it to an evaporator is formed by being bent substantially at a right angle on the way. ing.

The inlet side flow path 13a of the high pressure refrigerant flow path 13 is
An outlet-side flow path 13b connected to a liquid tank (not shown) and formed in a direction substantially perpendicular to the liquid tank,
It is connected to an evaporator not shown.

The main body block 11 has an outlet side flow path 13b.
Rod guide hole 14 having a circular cross section on the extension of the axis of
A power element 30 that operates by sensing a temperature change of the low-pressure refrigerant sent from the evaporator is attached to an outer open end portion of the rod guide hole 14.

At the boundary between the inlet-side flow path 13a and the outlet-side flow path 13b of the high-pressure refrigerant flow path 13, a valve having a circular cross-sectional shape whose flow path area is narrowed narrowly at the axial position of the outlet-side flow path 13b. A seat hole 15 is formed, and a spherical valve body 16 having a diameter larger than the diameter of the valve seat hole 15 is arranged to face the valve seat hole 15 from the downstream side.

The narrowest part of the gap between the valve element 16 and the outlet of the valve seat hole 15 becomes the narrowed portion of the high-pressure refrigerant flow path 13, and the downstream outlet side flow from the outlet to the evaporator. Road 13
Within b, the high-pressure refrigerant adiabatically expands.

The valve body 16 is urged in a direction approaching the valve seat hole 15 (ie, a valve closing direction) by a compression coil spring 17 arranged in the outlet side flow path 13b. On the front side of the receiving member 20 receiving one end of the compression coil spring 17 on the back side, a small hole (about half the diameter of the valve body 16) is formed in the center.
The valve element 16 is lightly fitted therein.

The other end of the compression coil spring 17 is received by an adjusting nut 18 screwed to the main body block 11. By rotating the adjusting nut 18 in the axial direction during assembly, the compression coil spring 17 is moved.
Can be adjusted.

A rod 23 having a circular cross section is inserted in the rod guide hole 14 formed in the main body block 11 so as to be able to advance and retreat in the axial direction. The rod 23 is guided and supported by the rod guide hole 14. I have. 24 is an O-ring for sealing.

As shown in an enlarged view in FIG. 2, one end of the rod 23 reaches the power element 30, an intermediate portion passes through the rod guide hole 14 and traverses the inlet side flow path 13a, and the other end face has a valve body. It is in contact with 16 heads.

As a result, the valve element 16 is urged by the power element 30 via the rod 23 in the valve opening direction. Note that the rod 23 is formed to be thinner than the valve seat hole 15 so that the refrigerant can pass between the wall surface of the valve seat hole 15 and the wall.

The rod guide hole 14 is formed with high precision so that the diameter does not exceed a value obtained by adding 0.02 mm to the diameter of the rod 23. Therefore, the play between the rod guide hole 14 and the rod 23 is very small.

The lower limit of the diameter of the rod guide hole 14 may be any value as long as it is larger than the diameter of the rod 23.
The lower limit is a dimension to which mm is added.

Returning to FIG. 1, the power element 30
A housing 31 made of a thick metal plate and a diaphragm 32 made of a flexible thin metal plate (for example, a stainless steel plate having a thickness of 0.1 mm) are hermetically enclosed.

The inside of the power element 30 communicates with a temperature-sensitive cylinder (not shown) for sensing a change in the temperature of the low-pressure refrigerant coming out of the evaporator via a capillary tube 34. A gas in a saturated vapor state having the same or similar properties to the refrigerant flowing in the refrigerant flow path 13 is sealed.

As shown in an enlarged view in FIG. 2, a dish-shaped diaphragm receiving plate 33 is disposed facing the center of the lower surface of the diaphragm 32, and one of the rods 23 is located at the center of the lower surface. The end faces are in contact.

Reference numeral 36 denotes a bush arranged so as to receive the end of the rod 23 movably in the axial direction and to restrict the movement of the O-ring 24. The rod 23 has no play near the outer end. Supported by the bushing 36.

Reference numeral 37 denotes an outlet side flow path 1 downstream of the valve seat 15.
This is a communication hole for communicating the inside of 3b and the back side of the diaphragm 32, and the portion on the back side of the diaphragm 32 has the same pressure as the outlet side flow path 13b.

In the expansion valve configured as described above,
When the temperature of the low-pressure refrigerant coming out of the evaporator decreases, the temperature of the thermosensitive cylinder decreases, and the saturated vapor gas in the power element 30 condenses on the inner surface of the diaphragm 32.

Then, the pressure in the power element 30 is reduced and the diaphragm 32 is displaced.
Is moved by being pressed by the compression coil spring 17, and as a result, the valve element 16 moves to the valve seat hole 15 side, and the flow passage area of the high-pressure refrigerant is reduced, so that the flow rate of the refrigerant sent to the evaporator is reduced.

When the temperature of the low-pressure refrigerant coming out of the evaporator rises, the valve body 16 is pushed by the rod 23 and separates from the valve seat hole 15 by the operation reverse to the above, and the flow path area of the high-pressure refrigerant increases. The flow rate of the high-pressure refrigerant sent to the evaporator increases.

In such an operation, as described above,
The diameter of the rod guide hole 14 is formed so as not to exceed a value obtained by adding 0.02 mm to the diameter of the rod 23, and there is only a slight play between the rod guide hole 14 and the rod 23.

Therefore, even in a control state where the flow rate of the refrigerant is extremely small, that is, in a state where the gap between the valve body 16 and the valve seat 15 is very narrow, the valve body 1 is caused by the lateral vibration of the valve body 16 or the like.
6 does not hit the valve seat 15, and no hitting sound is generated.

FIG. 3 shows an expansion valve according to a second embodiment of the present invention. As shown in a partially enlarged view in FIG. 4, a bush 36 is formed to be long in the axial direction, and the bush 36 is formed. 36, a rod guide hole 14 having a diameter dimension so that the rod 23 does not rattle is formed.

The dimensional relationship of the rod guide hole 14 with respect to the diameter of the rod 23 is the same as that of the first embodiment, and the diameter of the insertion hole 114 formed in the main body block 11 for passing the rod 23 is to some extent. It may be rough.

[0032]

According to the present invention, the diameter of the rod guide hole into which the rod interposed between the two for urging the valve element with the power element is set to 0.02 mm. Since the rod does not rattle in the rod guide hole because it is formed in a range that does not exceed the size with the addition of, the rod sways, etc. even when the gap between the valve body and the valve seat is in a controlled state. As a result, the valve body does not hit the valve seat, and no hitting sound is generated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an expansion valve according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the expansion valve according to the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of an expansion valve according to a second embodiment of the present invention.

FIG. 4 is a partially enlarged cross-sectional view of an expansion valve according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Main body block 13 Refrigerant flow path 14 Rod guide hole 15 Valve seat 16 Valve body 17 Compression coil spring 23 Rod 30 Power element

Claims (1)

[Claims] 1. A valve seat is formed in the middle of a high-pressure refrigerant flow path through which a high-pressure refrigerant sent to an evaporator passes, and a valve body is disposed opposite to the valve seat, and the valve body is closed by a spring in a valve closing direction. The valve element is moved in the valve opening direction through a rod that is interposed between the power element and the power element that operates by sensing the temperature of the low-pressure refrigerant sent from the evaporator. In the biased expansion valve, the diameter of the rod guide hole through which the rod is inserted to guide the rod so as to be able to advance and retreat in the axial direction does not exceed a value obtained by adding 0.02 mm to the diameter of the rod. An expansion valve, wherein the expansion valve is formed.