JPH1089811A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a hunting phenomenon from being presented to an expansion valve in an air conditioner. SOLUTION: An expansion valve 10 is provided with a temperature-sensitive bar 300 constituting a valve disc driving bar. The temperature-sensitive bar 300 has a constitution that its main body 310 made of aluminum is partly fitted into a resin member 330. The resin member 330 has an engaging edge 336 and is coupled to the main body 310 by engaging it with a groove 316 of the main body. With this assembling, since the resin member 330 is made of a material having low-thermal conductivity even in the case where, for example, an unevaporated refrigerant from an evaporator flows into a second passage 34 and adheres to the resin member 330, response characteristics of the expansion valve 10 become dull even under the thermal load of the evaporator, and, as a result, a hunting phenomenon to be possibly presented in a refrigerating system can be avoided.

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 a refrigerant used in a refrigeration cycle of an air conditioner, a refrigeration apparatus, and the like.

[0002]

2. Description of the Related Art An expansion valve of this type is used in a refrigeration cycle of an air conditioner of an automobile or the like.
1 shows a longitudinal sectional view of a conventional expansion valve together with an outline of a refrigeration cycle. The expansion valve 10 is a prismatic aluminum valve body 3.
In the refrigerant line 11 of the refrigeration cycle, the evaporator 8 is connected to the refrigerant outlet of the condenser 5 via the receiver 6.
In the first passage 32 and the refrigerant pipe 11 through which the liquid-phase refrigerant interposed at the portion toward the refrigerant inlet passes, an evaporator is provided.
Second passage 34 through which a gas-phase refrigerant interposed at a portion from the refrigerant outlet of the compressor 8 to the refrigerant inlet of the compressor 4 passes.
Are formed vertically separated from each other.

In the first passage 32, an orifice 32a for adiabatically expanding the liquid refrigerant supplied from the refrigerant outlet of the receiver 6 is formed. The orifice 32a is located on a center line along the longitudinal direction of the valve body 30. A valve seat is formed at an inlet of the orifice 32a, and a valve body 32b supported by a valve member 32c is present at the valve seat, and the valve body 32b and the valve member 32c are fixed by welding. The valve member 32c is fixed to the valve body by welding and is urged by urging means 32d such as a compression coil spring. The first where the liquid refrigerant from the receiver 6 is introduced
Passage 32 serves as a passage for the liquid refrigerant and has an inlet port 321.
And a valve chamber 35 connected to the inlet port 321. The valve chamber 35 is a chamber with a bottom formed coaxially with the center line of the orifice 32 a, and is closed by a plug 39.

Further, in order to apply a driving force to the valve body 32b in accordance with the outlet temperature of the evaporator 8 to open and close the orifice 32a, the valve body 30 has a small diameter hole 37 and a diameter larger than the hole 37. A hole 38 having a diameter is formed through the second passage 34 on an extension of the center line, and a screw hole 361 is formed at an upper end of the valve body 30 to which a power element portion 36 serving as a heat sensitive portion is fixed. I have.

The power element 36 is provided with a diaphragm 36a made of stainless steel and an upper pressure working chamber 36b and a lower pressure working chamber 3 which are provided in close contact with each other with the diaphragm 36a therebetween and form two airtight chambers above and below the diaphragm 36a.
6c and upper cover 36d and lower cover 36, respectively.
h, and a sealing tube 36i for sealing a predetermined refrigerant serving as a diaphragm driving fluid in the upper pressure working chamber 36b,
The lower pressure working chamber 36c communicates with the second passage 34 via a pressure equalizing hole 36e formed concentrically with the center line of the orifice 32a. Refrigerant vapor from the evaporator 8 flows through the second passage 34, and the passage 34 serves as a passage for a gas-phase refrigerant, and the pressure of the refrigerant vapor is applied to the lower pressure working chamber 36c via the equalizing hole 36e. .

Further, the evaporator 8 abuts on the diaphragm 36a in the lower pressure working chamber 36c and is slidably disposed in the large-diameter hole 38 through the second passage 34.
Is transmitted to the lower pressure working chamber 36c, and the large diameter 3 according to the displacement of the diaphragm 36a due to the pressure difference between the upper pressure working chamber 36b and the lower pressure working chamber 36c.
Aluminum temperature sensing rod 36f which gives a driving force by sliding in the inside 8
And a temperature sensing rod 36f slidably disposed in the small diameter hole 37.
A stainless steel operating rod 37f which presses the valve body 32b against the elastic force of the urging means 32d in accordance with the displacement of
A sealing member for ensuring airtightness between the first passage 32 and the second passage 34, for example, an O-ring 3
6g is provided, the temperature sensing rod 36f and the operating rod 37f are in contact with each other, and the operating rod 37f is in contact with the valve body 32b,
The valve element driving rod is constituted by the temperature sensing rod 36f and the operating rod 37f. Therefore, the valve drive rod extending from the lower surface of the diaphragm 36a to the orifice 32a of the first passage 32 is concentrically arranged in the pressure equalizing hole 36e.

A known diaphragm driving fluid is filled in the pressure operating chamber 36b above the pressure operating housing 36d, and the diaphragm driving fluid is uniformly communicated with the second passage 34 and the second passage 34. The heat of the refrigerant vapor from the refrigerant outlet of the evaporator 8 flowing through the second passage 34 is transmitted via the valve body driving rod exposed to the pressure hole 36e and the diaphragm 36a.

[0008] The diaphragm driving fluid in the upper pressure working chamber 36b is gasified in response to the transferred heat and applies pressure to the upper surface of the diaphragm 36a. Diaphragm 3
6a is displaced up and down due to the difference between the pressure of the diaphragm driving gas applied to the upper surface and the pressure applied to the lower surface of the diaphragm 36a. The displacement of the center of the diaphragm 36a in the vertical direction is transmitted to the valve body 32b via the valve body drive rod, and moves the valve body 32b toward or away from the valve seat of the orifice 32a. As a result, the flow rate of the refrigerant is controlled.

That is, since the temperature of the gas-phase refrigerant at the outlet side of the evaporator 8 is transmitted to the upper pressure working chamber 36b, the pressure in the upper pressure working chamber 36b changes according to the temperature, and the outlet temperature of the evaporator 8 rises. I do. That is, when the heat load of the evaporator increases, the pressure in the upper pressure working chamber 36b increases, and accordingly, the temperature sensing rod 36f, that is, the valve member drive rod is driven downward, and the valve body 3
2b, the opening of the orifice 32a increases. Thus, the supply amount of the refrigerant to the evaporator 8 increases, and the temperature of the evaporator 8 decreases. Conversely, when the outlet temperature of the evaporator 8 decreases, that is, when the heat load of the evaporator decreases, the valve element 32b is driven in the opposite direction to the above, the opening degree of the orifice 32a decreases, and the supply amount of the refrigerant to the evaporator decreases. Less, evaporator 8
Raises the temperature.

[0010]

In a refrigeration system using such an expansion valve, there is known a so-called hunting phenomenon in which the supply of refrigerant to an evaporator repeats in a short cycle of excess, shortage, excess, and shortage. This is because when the expansion valve is affected by the environmental temperature, for example, the unevaporated liquid refrigerant adheres to the temperature sensing rod of the expansion valve and senses this as a temperature change, causing a change in the heat load of the evaporator, resulting in hypersensitivity. It is based on a simple valve opening / closing response.

When such a hunting phenomenon occurs, there is a problem that the capacity of the entire refrigeration system is reduced, and a liquid is returned to the compressor, which adversely affects the compressor. The present applicant has proposed an expansion valve shown in FIG. 5 as Japanese Patent Application No. 7-325357. The expansion valve 10 is provided with a low thermal conductivity resin 10 on a temperature sensing rod 100 constituting an aluminum valve body driving rod.
1 is integrally formed in an insert-formed state so as to be in close contact with the temperature-sensitive stick 100. As the resin 101 having a low thermal conductivity, for example, PPS which does not change over time due to the influence of a refrigerant or the like
Resin is used. The resin 101 is provided not only at the portion of the temperature sensing rod 100 exposed in the second passage 34 through which the gas-phase refrigerant passes but also at the temperature sensing portion existing in the lower pressure working chamber 36c. The thickness of the resin 101 is, for example, about 1 mm.

In addition, the resin 101 is at least
Of course, it may be provided only in a portion exposed in the second passage 34 of the zero. By providing such a resin 101, for example, the unevaporated refrigerant from the evaporator flows into the second passage 34, and even if it adheres to the resin 101, the resin 101 is a material having a low thermal conductivity. Even if the fluctuation, that is, the increase of the heat load of the evaporator, occurs, the response characteristic of the expansion valve 10 becomes insensitive, and the occurrence of the hunting phenomenon in the refrigeration system can be avoided. The above-mentioned expansion valve has a problem that it is necessary to insert the resin 101 into the aluminum temperature sensing rod 100, and the manufacturing process is costly. The present invention has been made in view of such a problem, and an object of the present invention is to provide an expansion valve that prevents a hunting phenomenon from occurring in a refrigeration system with a simple configuration change. is there.

[0013]

In order to achieve the above object,
An expansion valve according to the present invention includes a valve body having a first passage through which a liquid refrigerant passes and a second passage through which a gas-phase refrigerant passes from an evaporator to a compressor; an orifice provided in the first passage; A valve element for adjusting the amount of refrigerant passing therethrough, a power element section provided on the valve body and having a diaphragm operated by a pressure difference between the upper and lower sides thereof, and one end for driving the valve element by displacement of the diaphragm. A temperature sensing rod which contacts the diaphragm and drives the valve body at the other end. The temperature sensing rod is characterized in that a resin member having a low thermal conductivity is fitted to a portion close to the diaphragm.

In another aspect of the expansion valve according to the present invention, a valve body having a first passage through which a liquid refrigerant passes and a second passage through which a gas-phase refrigerant passes from an evaporator to a compressor is provided. An orifice provided in the passage, a valve element for adjusting the amount of refrigerant passing through the orifice, a power element portion provided on the valve body and having a diaphragm operated by a pressure difference between the upper and lower sides, and a displacement of the diaphragm One end for driving the valve element is in contact with the diaphragm, and the other end includes a temperature-sensitive rod for driving the valve element.The temperature-sensitive rod has a concave portion and is fitted in the concave portion. It is characterized by comprising a resin member loosely fitted around the outer periphery of the temperature sensing rod.

In another aspect of the expansion valve of the present invention, the temperature sensing rod is characterized in that the resin member is fitted by the elasticity of the member. In a specific aspect of the expansion valve according to the present invention, the concave portion is formed in a portion of the temperature sensing rod existing in the second passage through which the gaseous refrigerant passes. Further, as a specific mode of the expansion valve of the present invention, the resin member is a polyacetal resin.

Further, as a specific embodiment of the expansion valve of the present invention, the resin member has a flange-like portion formed on the side facing the diaphragm, and the inside of an end opposite to the flange protrudes. A part is formed, and the projecting part is fitted in the concave part. The expansion valve according to the present invention configured as described above can operate the valve body even when there is a transient change in the environmental temperature that causes an excessive valve opening / closing response of the expansion valve that causes a hunting phenomenon of the refrigeration system. Since the heat conduction speed of the temperature sensing rod of the rod is reduced, the above-mentioned sensitive valve opening / closing response can be avoided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an expansion valve 1 according to the present embodiment.
FIG. 4 is a longitudinal sectional view of FIG.
The same reference numerals indicate the same or equivalent parts, and control the refrigerant supply amount.

FIG. 2 is a front view of the main body of the temperature sensing rod 300 shown in FIG. 1, and FIG. 3 is a sectional view of the resin member. The expansion valve 10
A main body 30 made of aluminum is provided, and the main body 30 is provided with a seventeenth passage 32 for the liquid-phase refrigerant and a second passage 34 for the gas-phase refrigerant described in FIG.
Having. The valve body 32b disposed in the valve chamber 35 has the operating rod 3
7 is connected to the temperature sensing rod 300. Temperature sensing bar 300
Has a main body 310 of a cylindrical member made of aluminum and a resin member 330 fitted on the outside of the main body. As shown in FIG. 2, the temperature sensing rod main body 310 includes a receiving portion 312 of the diaphragm 36a, a large diameter portion 314 slidably inserted into the lower cover 36h of the power element portion 36, and a second passage 34.
It has a temperature sensing part 318 exposed inside and a groove part 320 in which a seal member is fitted. And the temperature sensing rod body 310
In the middle thereof, for example, a concave portion, for example, a shallow groove portion 316 is provided between the large diameter portion 314 and the groove portion 320.

FIG. 3 is a sectional view of the resin member 330. The resin member 330 has an inner diameter that is loosely fitted to the outer peripheral portion of the temperature sensing portion 318 of the temperature sensing rod body 310, and is a resin member 330 made of a resin material having a low thermal conductivity, for example, polyacetal resin. The size is, for example, 1 mm or more. In the present embodiment, for example, the outer diameter of the temperature sensing rod main body 318 is 5.6 mm, and the inner diameter of the resin member is 5.8 mm. The side of the resin member 330 facing the diaphragm is formed on the flange portion 332, and the inner peripheral portion at the end opposite to the flange portion 332 has an engaging edge 3 protruding inward.
36 (for example, a height of 0.2 mm) are provided. The resin member 330 is fitted to the temperature sensing rod main body 310 and the engaging edge 3
36 is the temperature-sensitive rod main body 3 in the second passage through which the gas-phase refrigerant passes.
By fitting into a concave portion (for example, a depth of 0.2 mm) 316 formed in the portion 10, the resin member is fitted by elasticity.

The refrigerant in the second passage 34 is supplied to the resin member 330.
When it adheres, the transmission of temperature information to the diaphragm is delayed due to the low thermal conductivity of the resin. Therefore, in the temperature sensing rod made of aluminum having a high thermal conductivity, by using a resin member and reducing the heat transfer rate, the heat transfer rate of the heat transferred to the diaphragm can be reduced. Thereby, the occurrence of the hunting phenomenon can be prevented.

[0021]

As will be understood from the above description, the expansion valve according to the present invention can prevent an excessive valve opening / closing response of the expansion valve, and can avoid a hunting phenomenon that occurs in a refrigeration cycle.

[Brief description of the drawings]

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

FIG. 2 is a front view of a temperature sensing rod main body.

FIG. 3 is a sectional view of a resin member.

FIG. 4 is a vertical cross-sectional view of a conventional expansion valve and a view schematically showing a refrigeration cycle.

FIG. 5 is a longitudinal sectional view of an expansion valve proposed by the present applicant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Expansion valve 30 Valve main body 32a Orifice 32b Valve body 36 Power element 36a Diaphragm 300 Temperature sensing rod 310 Temperature sensing rod main body 330 Resin member

Claims (6)

[Claims] 1. A valve body having a first passage through which a liquid refrigerant passes and a second passage through which a gas-phase refrigerant passes from an evaporator to a compressor, an orifice provided in the first passage, and a passage through the orifice. A valve body for adjusting the amount of refrigerant,
A power element portion provided on the valve body and having a diaphragm operated by a pressure difference between the upper and lower sides, and one end driving the valve body by displacement of the diaphragm is in contact with the diaphragm at one end and the valve body at the other end. An expansion valve, comprising a driven temperature sensing rod, wherein the temperature sensing rod has a resin member having low thermal conductivity fitted in a portion close to the diaphragm. 2. The expansion valve according to claim 1, wherein the temperature sensing rod is fitted with the resin member by elasticity of the member. 3. The expansion valve according to claim 1, wherein the resin member is a polyacetal resin. 4. A valve body having a first passage through which a liquid refrigerant passes and a second passage through which a vapor-phase refrigerant passes from an evaporator to a compressor; an orifice provided in the first passage; and an orifice passing through the orifice. A valve body for adjusting the amount of refrigerant,
A power element portion provided on the valve body and having a diaphragm operated by a pressure difference between the upper and lower sides, and one end driving the valve body by displacement of the diaphragm is in contact with the diaphragm at one end and the valve body at the other end. A temperature-sensitive stick to be driven, the temperature-sensitive stick having a concave portion,
An expansion valve, comprising: a resin member which is fitted into the recess so as to be loosely fitted to the outer periphery of the temperature sensing rod. 5. The resin member has a flange-like portion formed on the side facing the diaphragm, and a protruding portion formed inside an end opposite to the flange portion, and the protruding portion is fitted into the concave portion. The expansion valve according to claim 4, wherein the expansion valve is provided. 6. The expansion valve according to claim 4, wherein the concave portion is formed in a portion of the temperature sensing rod existing in a second passage through which the gas-phase refrigerant passes.