JPH09159324A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hunting relating to the expansion valve in an air- conditioning apparatus. SOLUTION: An expansion valve 10 has a temperature-sensitive rod 100 which constitutes a valve-driving aluminum rod and on which a resin 101 with a low thermal conductivity, formed by insert molding, is placed in tight contact and integrally in one piece with the temperature-sensitive rod 100. For this low thermal-conductivity resin 101 use is made of, for example, PPS which is not susceptible to a aging caused by a refrigerant, etc. The resin 101 is provided on the temperature-sensitive rod 100, besides the part which is exposed in a second passageway 34 for the passage of a gas-phase refrigerant, up to the part located inside a pressure-acting chamber 36c positioned lower. The resin 101 is formed in a thickness of, for example, about 1mm. By providing such a resin 101, even when, for example, refrigerant from an evaporator which has not yet vaporized flows into the second passageway 36 and sticks to the resin 101, although the heat load of the evaporator may vary, that is, the heat load of the evaporator may increase, the fact that the resin 101 is of material of low thermal conductivity makes the response characteristic of the expansion valve 10 dull and enables avoiding hunting in the refrigeration system.

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 This type of expansion valve is used in a refrigeration cycle of an air conditioner for automobiles and 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 has 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 passage 32 into which the liquid refrigerant from the receiver 6 is introduced serves as a passage for the liquid refrigerant, and has an inlet port 321 and a valve chamber 35 continuous with 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 portion 36 is provided with a stainless steel diaphragm 36a and the diaphragm 36a so as to be in close contact with each other. The upper pressure working chamber 36b and the lower pressure working chamber 3 form two airtight chambers above and below the diaphragm 36a.
6c and upper cover 36d and lower cover 36, respectively.
h, and a shutoff tube 36i for enclosing 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, the passage 34 serves as a vapor-phase refrigerant passage, and the pressure of the refrigerant vapor is applied to the lower pressure working chamber 36c through the pressure 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. Accordingly, 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.

The pressure actuating chamber 36b above the pressure actuating housing 36d is filled with a known diaphragm driving fluid, and the diaphragm driving fluid is 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 transferred via the valve body drive 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 by 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. In other words, 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 to lower the valve body 32b, so that the opening degree of the orifice 32a is increased. Becomes larger. 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 on the evaporator decreases, the valve body 32b is driven in the opposite direction to the above, and the orifice 32a
Is small, the supply amount of the refrigerant to the evaporator is reduced, and the temperature of the evaporator 8 is increased.

[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 invention has been made in view of such a problem,
It is an object of the present invention to provide an expansion valve that can prevent a hunting phenomenon from occurring in a refrigeration system with a simple configuration change.

[0012]

[Means for Solving the Problems] To achieve the above object,
The expansion valve according to the present invention includes a first passage through which the liquid refrigerant passes and a second passage through which the gas-phase refrigerant passes from the evaporator to the compressor.
An orifice provided in the passage of the liquid refrigerant, a valve body for adjusting the amount of the refrigerant passing through the orifice, and a diaphragm provided in the valve body and operated by a pressure difference above and below the valve body. And a temperature-sensitive rod that is in contact with the diaphragm at one end that drives the valve element by the displacement of the diaphragm and that drives the valve element at the other end, and at least the temperature-sensitive rod of the temperature-sensitive rod It is characterized in that a material having a low thermal conductivity is provided on the surface of the exposed portion in the second passage.

Another aspect of the expansion valve of the present invention is characterized in that a resin is used as the material and the resin is provided on the surface by insert molding. Further, another aspect of the expansion valve of the present invention is characterized in that the material is press-fitted into a recess provided in the valve body drive rod.
The expansion valve according to the present invention configured as described above, even if there is a transient change in the environmental temperature that causes a hypersensitive valve opening / closing response of the expansion valve, which causes the hunting phenomenon of the refrigeration system,
Since the valve body drive rod is made of a material having a low thermal conductivity, the above-mentioned sensitive valve opening / closing response can be avoided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a vertical cross-sectional view of an expansion valve 10 according to the present embodiment, in which the refrigeration cycle is omitted and the same reference numerals as those in FIG. 3 indicate the same or equivalent portions and control the refrigerant supply amount. The expansion valve 10 is integrated so that a resin 101 having a low thermal conductivity is insert-formed into a temperature sensing rod 100 constituting an aluminum valve body driving rod, and is closely attached to the temperature sensing rod 100. As the low thermal conductivity resin 101, for example, a PPS resin that does not change with time due to the influence of a refrigerant or the like 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.

Further, the resin 101 is at least the temperature sensitive rod 10.
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.

FIG. 2 is a longitudinal sectional view of an expansion valve 10 according to another embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same or equivalent portions, and a groove 102 is formed in a temperature sensitive rod 100. As the rubber material 103 having refrigerant resistance, for example, 36 g of O-ring
The rubber material 103 is press-fitted into the groove 102 by using the same material as the above. With this configuration, it is needless to say that the same operation as that of the expansion valve of FIG. 1 is achieved.

[0017]

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 longitudinal sectional view of an expansion valve according to another embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a conventional expansion valve and a schematic view of a refrigeration cycle.

[Explanation of reference numerals] 10 expansion valve 30 valve body 32a orifice 32b valve body 36 power element 36a diaphragm 100 temperature sensitive rod 101 resin

Claims (3)

[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, which has a diaphragm that operates by a pressure difference between the upper and lower sides, and a displacement of the diaphragm drives the valve element. One end of the valve element contacts the diaphragm and the other end drives the valve element. An expansion valve comprising a temperature-sensitive rod that has a low thermal conductivity provided on at least the exposed surface of the temperature-sensitive rod in the second passage. 2. The expansion valve according to claim 1, wherein the material having a low thermal conductivity is insert molded resin. 3. The expansion valve according to claim 1, wherein the material having a low thermal conductivity is a rubber material.