JP2000241048A - Thermal expansion valve - Google Patents

Abstract

(57) [Problem] To provide a temperature-sensitive expansion valve that can be used for superheat control in a supercritical region or a high-pressure region. A valve closing spring made of a temperature-sensitive material for driving a valve body in a valve closing direction in response to a refrigerant temperature on an inlet side of an evaporator.
9 and the valve element 33 in response to the refrigerant temperature at the outlet side of the evaporator 9.
And a valve opening spring 61 made of a temperature-sensitive material for driving the evaporator 9 in the valve opening direction, and operated by a temperature difference between the refrigerant temperature at the inlet side of the evaporator 9 and the refrigerant temperature at the outlet side of the evaporator. At
In order to reduce the refrigerant pressure Pc of the condenser 3 acting on the valve body 33, a direction opposite to the direction in which the refrigerant pressure of the condenser 3 acts on the valve body 33 is applied to the valve stem portion (the connecting rod 37) of the valve body 33. A pressure receiving surface (pressure receiving step surface 65) is provided in the direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-sensitive expansion valve used in a refrigeration / refrigeration cycle device, and more particularly to a temperature-sensitive expansion valve for controlling a flow rate of a refrigerant flowing from a condenser to an evaporator according to the degree of superheat of the refrigerant. It relates to a valve (temperature expansion valve).

[0002]

2. Description of the Related Art In general, in a refrigerating / refrigerating apparatus, a flow rate of a refrigerant flowing from a condenser to an evaporator is controlled by a temperature-sensitive expansion valve in accordance with a temperature load of the evaporator. It has been practiced to maintain the degree of superheat of the refrigerant at a predetermined value.

As a conventional temperature-sensitive expansion valve, a valve closing spring (bias spring) for driving a valve body in a valve closing direction and a valve body in an opening direction in response to a refrigerant temperature at an outlet side of an evaporator. The valve element is opened and closed by the balance of a bimetal or shape memory alloy valve-opening spring (thermally responsive member) to control the flow rate of the refrigerant flowing from the condenser to the evaporator according to the refrigerant temperature at the outlet side of the evaporator. An expansion valve is disclosed in JP-A-51-82444 and JP-B-58-10623.

Further, as a conventional temperature-sensitive expansion valve, a valve closing spring made of a shape memory alloy for driving a valve body in a valve closing direction in response to a refrigerant temperature on an inlet side of an evaporator, The valve body is opened and closed by an equilibrium relationship with a valve spring made of a shape memory alloy that drives the valve body in the valve opening direction in response to the refrigerant temperature, and the refrigerant temperature at the inlet of the evaporator and the outlet side of the evaporator are driven. An expansion valve for controlling the flow rate of a refrigerant flowing from a condenser to an evaporator in accordance with a temperature difference from the refrigerant temperature is disclosed in Japanese Patent Application Laid-Open No. 2-67987.

[0005]

Problems to be Solved by the Invention
No. 4 and Japanese Patent Publication No. 58-10623 do not have a pressure-sensitive element such as a bellows or a diaphragm device, and can withstand high-pressure specifications. Since it only responds to temperature, there is a limit to the functional characteristics of a constant-temperature expansion valve that maintains the degree of superheat at a constant value.

On the other hand, a temperature-sensitive expansion valve disclosed in Japanese Patent Application Laid-Open No. 2-698787 is sensitive to the temperature of the refrigerant at the inlet of the evaporator and to the temperature of the refrigerant at the outlet of the evaporator. A valve opening spring that controls the flow rate of the refrigerant flowing from the condenser to the evaporator in accordance with the temperature difference between the refrigerant temperature on the inlet side of the evaporator and the refrigerant temperature on the outlet side of the evaporator. It is useful as a constant temperature type expansion valve for maintaining a constant value.

However, from the installation position of the thermal expansion valve in the refrigeration cycle, it is inevitable that the refrigerant pressure of the condenser acts on the valve body of the thermal expansion valve in the valve opening direction or the valve closing direction. If the refrigerant pressure of the condenser is in the valve opening direction, the opposing spring force of the valve-closing spring is set accordingly, and if the refrigerant pressure of the condenser is in the valve closing direction, the opposing opening force is set. It is necessary to make the spring force of the valve spring commensurate with it, and in the case of high-pressure specifications, the spring force of the valve-closing spring or the valve-opening spring needs to be considerably large.

However, since the spring force of the shape memory alloy spring is weak, it is difficult to apply the spring to a high pressure specification spring. Further, the temperature range of the shape memory alloy is about 20 ° C. at the most, so that it is not possible to cope with a wide temperature range and inflection characteristics.
It is difficult to obtain a constant temperature expansion valve in a wide temperature range.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is not limited to a normal vapor compression refrigeration cycle, but also to a supercritical region or high pressure in a refrigeration cycle using CO ₂ gas. Can also be used for superheat control in
It is another object of the present invention to provide a temperature-sensitive expansion valve capable of performing superheat control over a wide temperature range and having a control characteristic adapted to an optimum control line and an inflection characteristic calculated based on system efficiency. And

[0010]

In order to achieve the above object, a temperature-sensitive expansion valve according to the first aspect of the present invention has a valve body in a valve closing direction in response to a refrigerant temperature at an inlet side of an evaporator. A valve-closing spring made of a temperature-sensitive material that drives the valve body in a valve-opening direction in response to a refrigerant temperature on the outlet side of the evaporator; In the temperature-sensitive expansion valve that operates by the temperature difference between the refrigerant temperature on the inlet side of the evaporator and the refrigerant temperature on the outlet side of the evaporator, to reduce or eliminate the refrigerant pressure of the condenser acting on the valve body, The valve stem of the valve body is provided with a pressure receiving surface for receiving the refrigerant pressure of the condenser in a direction opposite to a direction in which the pressure acts on the valve body.

According to a second aspect of the present invention, there is provided a temperature-sensitive expansion valve, comprising: an inlet-side refrigerant passage through which a refrigerant at an inlet side of the evaporator flows;
An outlet-side refrigerant passage through which the refrigerant on the outlet side of the evaporator flows,
A valve housing having a valve port formed in the middle of the inlet-side refrigerant passage, and a valve body that opens and closes the valve port;
A connecting rod fixedly connected to the valve body at one end and exposed in the outlet-side refrigerant passage at the other end, and an inlet-side refrigerant downstream of the valve port in the inlet-side refrigerant passage in the flow of the refrigerant from the valve port; A valve closing spring made of a temperature-sensitive material that is provided between the valve body and the valve housing in the passage portion and that drives the valve body in a valve closing direction in response to a refrigerant temperature on an inlet side of the evaporator; A temperature-sensitive material that is provided between the connecting rod and the valve housing in the outlet-side refrigerant passage and drives the valve body in the valve opening direction in response to the refrigerant temperature on the outlet side of the evaporator. A valve-opening spring, wherein the connecting rod reduces or eliminates the refrigerant pressure of the condenser acting as the pressure in the valve-opening direction on the valve body in order to reduce or eliminate the refrigerant pressure of the condenser in the valve-closing direction. It has a pressure receiving step surface that receives pressure.

According to a third aspect of the present invention, in the temperature-sensitive expansion valve, the valve closing spring and the valve opening spring are formed of a shape memory alloy.

According to a fourth aspect of the present invention, in the temperature-sensitive expansion valve, the valve closing spring and the valve opening spring are made of bimetal.

According to a fifth aspect of the present invention, the temperature characteristic of the valve-closing spring is the same as the temperature characteristic of the valve-opening spring, and the temperature-sensitive expansion valve exhibits a constant differential temperature operation characteristic.

According to a sixth aspect of the present invention, there is provided a temperature-sensitive expansion valve, wherein each of the valve-closing spring and the valve-opening spring comprises a plurality of springs.

According to a seventh aspect of the present invention, there is provided a temperature-sensitive expansion valve, wherein at least one of the valve-closing spring and the valve-opening spring is adjusted via an adjusting screw-type spring receiving member screwed to the valve housing. To engage with the valve housing to adjust the initial load (reference load) of the spring.

In the temperature-sensitive expansion valve according to the first aspect of the present invention, the refrigerant pressure of the condenser acts on the pressure receiving surface formed on the valve stem portion of the valve body, so that the pressure of the condenser by the refrigerant pressure of the condenser is increased. The driving force in the valve opening direction or the valve closing direction is reduced or eliminated, and the invention can be applied to a high-pressure specification even if a shape memory alloy spring is used.

In the temperature-sensitive expansion valve according to the second aspect of the invention, the refrigerant pressure of the condenser acts on the pressure receiving step surface of the connecting rod as pressure in the valve closing direction and acts on the valve body as pressure in the valve opening direction. The refrigerant pressure in the condenser is reduced or completely canceled, and the present invention can be applied to a high-pressure specification even if a shape memory alloy spring (valve closing spring) is used.

In the temperature-sensitive expansion valve according to the third aspect of the present invention, the valve-closing spring and the valve-opening spring are made of a shape memory alloy, so that required temperature-sensitive spring characteristics can be easily obtained.

In the temperature-sensitive expansion valve according to the fourth aspect of the invention, the valve-closing spring and the valve-opening spring are made of bimetal, so that required temperature-sensitive spring characteristics can be obtained over a wide range.

In the temperature-sensitive expansion valve according to the fifth aspect of the invention, the temperature characteristics of the valve-closing spring and the temperature characteristics of the valve-opening spring are the same, and a constant temperature difference operating characteristic is obtained.

In the temperature-sensitive expansion valve according to the sixth aspect of the invention, each of the valve-closing spring and the valve-opening spring is constituted by a plurality of springs. Different temperature operating characteristics are obtained.

In the temperature-sensitive expansion valve according to the present invention, at least one of the valve-closing spring and the valve-opening spring is adjusted via the adjusting screw-type spring receiving member which is adjustably screwed to the valve housing. The reference load can be adjusted by engaging with the valve housing.

[0024]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(Embodiment 1) FIG. 1 shows an embodiment of a refrigeration / refrigeration cycle apparatus including a temperature-sensitive expansion valve according to the present invention. The refrigeration / refrigeration cycle device has a compressor 1, a condenser (condenser) 3, a receiver 5, a temperature-sensitive expansion valve 7, and an evaporator (evaporator) 9, and these are refrigerant pipes 11, 13, The loop connection is made by 15, 17, 19a and 19b.

The temperature-sensitive expansion valve 7 has a valve housing 21 made of an aluminum alloy or the like. The valve housing 21 connects an inlet port 23 to which the refrigerant pipe 15 on the condenser 3 side is connected and a refrigerant pipe 17 on the inlet side of the evaporator 9 as an inlet side refrigerant passage through which the refrigerant on the inlet side of the evaporator 9 flows. An outlet port 25 is provided, a valve port 27 is formed between the inlet port 23 and the outlet port 25, and a valve chamber 29 is formed on the outlet port 25 side.

In the valve housing 21, outlet-side refrigerant passages 31, 31 'through which the refrigerant on the outlet side of the evaporator 9 flows are formed. A refrigerant pipe 19a is connected to one of the outlet-side refrigerant passages 31, and a refrigerant pipe 19b is connected to the other outlet-side refrigerant passage 31 '. Part.

A valve body 33 for opening and closing the valve port 27 is disposed in the valve chamber 29. The valve housing 21 movably holds a connecting rod (valve stem) 37 in the valve stem support hole 35. The connecting rod (valve stem) 37 is fixedly connected to the valve body 33 at one end (lower end), penetrates the valve stem support hole 35, and is exposed at the other end (upper end) in the outlet side refrigerant passages 31, 31 '. are doing. In addition, a seal member 39 for keeping the airtightness between the inlet port 23 and the outlet-side refrigerant passages 31 and 31 ′ is provided at an intermediate portion of the connecting rod 37.

An adjusting screw type spring receiving member 43 which is adjustably screwed to the valve housing 21 by a screw portion 41 is hermetically attached to a lower portion of the valve housing 21 by a sealing member 45. A first valve-closing spring (compression coil spring) 49 made of a shape memory alloy (SMA) for urging the valve 33 in the valve closing direction between the spring receiving member 47 engaged with the valve 33. And a second valve-closing spring (compression coil spring) 51 made of ordinary spring steel are provided in a double spring system.

The first valve closing spring 49 and the second valve closing spring 51
Are both located in the valve chamber 29 downstream of the valve port 27,
The first valve closing spring 49 drives the valve body 33 in the valve closing direction in response to the refrigerant temperature Te on the inlet side of the evaporator 9 flowing through the valve chamber 29.

A spring receiving member 55 fixed to the valve housing 21 by a snap ring 53 is hermetically attached to the upper portion of the valve housing 21 by a seal member 57. The spring receiving member 55 and the outlet side refrigerant passage 31 are provided. , 31 ′ between the spring receiving member 59 fixed to the upper end of the connecting rod 37 and the first valve opening made of a shape memory alloy (SMA) for urging the valve body 33 in the valve opening direction. A spring (compression coil spring) 61 and a second valve-opening spring (compression coil spring) 63 made of normal spring steel are provided in a double spring system.

The first valve opening spring 61 and the second valve opening spring 63
Are in the outlet side refrigerant passages 31 and 31 ′, and the valve body 33 is opened via the connecting rod 37 in response to the refrigerant temperature on the outlet side of the evaporator 9 flowing through the outlet side refrigerant passages 31 and 31 ′. Drive in the direction.

The first valve-closing spring 49 and the first valve-opening spring 61 are made of a shape memory alloy having the same temperature characteristics (temperature-generating force characteristics).

The valve body 33 receives the refrigerant pressure Pc of the condenser 3 through the valve port 27 as the pressure in the valve opening direction, while the connecting rod 37 has a small diameter at the inlet port 23 side. It has a pressure receiving step surface 65 that receives the refrigerant pressure Pc of the condenser as a pressure in the valve closing direction.

Assuming that the diameter of the valve port 27 is Da and the outer diameter of the connecting rod 37 on the large diameter side is Db, Da ≧ Db
In b, the magnitude relation is set to about Da = (0.7 to 1.0) Db.

Next, the operation of the temperature-sensitive expansion valve 7 having the above configuration will be described.

The initial load (reference load) of the first valve closing spring 49 and the second valve closing spring 51 is set to be adjustable by the adjusting screw type spring receiving member 43. The first valve closing spring 49 is a valve. It is sensitive to the refrigerant temperature Te on the inlet side of the evaporator 9 flowing through the chamber 29.

The refrigerant that has absorbed and overheated by flowing through the evaporator 9 flows through the outlet-side refrigerant passages 31 and 31 ′ at a pressure Pe ′ and a temperature Te ′, and the first valve-opening spring 61 is connected to the outlet side of the evaporator 9. In response to the refrigerant temperature Te ′.

Generally, the refrigerant pressure P on the inlet side of the evaporator 9
e and the refrigerant pressure Pe ′ on the outlet side of the evaporator 9 are substantially the same, and when the degree of superheat of the refrigerant is zero, the refrigerant temperature Te on the inlet side of the evaporator 9 and the refrigerant temperature Te on the outlet side of the evaporator 9 'Is almost the same.

When the degree of superheat of the refrigerant occurs, Te <Te 'is established, and a temperature difference is generated between the two temperature-sensitive spring portions (the first valve-closing spring 49 and the first valve-opening spring 61). Accordingly, a difference occurs between the generated spring forces of the first valve closing spring 49 and the first valve opening spring 61.

When the difference between the generated spring forces becomes larger than the reference load (the degree of superheat increases), the valve opening force increases, the valve opening amount of the valve body 33 increases, and the amount of refrigerant supplied to the evaporator 9 increases. . Thereby, the refrigerant temperature Te ′ on the outlet side of the evaporator 9 tends to decrease.

On the other hand, when the difference in the generated spring force is lower than the reference load or the current value (the degree of superheat is reduced), the valve opening force is reduced, and the valve opening amount of the valve body 33 is reduced. Refrigerant supply amount decreases. Thereby, a decrease in the refrigerant temperature Te ′ on the outlet side of the evaporator 9 is suppressed.

By the above-described operation, a constant differential temperature operation characteristic is obtained, and the degree of superheat of the refrigerant can be kept constant over the entire operation range without being affected by the physical properties of the refrigerant of the apparatus.

A refrigerant having a refrigerant pressure Pc of the condenser 3 and a refrigerant temperature Tc flows through the inlet port 23 of the temperature-sensitive expansion valve 7, and a relatively high refrigerant pressure Pc is supplied through the valve port 27 to the valve 33.
The refrigerant pressure Pc simultaneously acts on the pressure receiving step surface 65 of the connecting rod 37 in the opposite direction, that is, as a pressure in the valve closing direction, and the valve opening actually acting on the valve body 33. Reduces pressure.

Here, (the diameter Da of the valve port 27) =
(The outer diameter Db on the large diameter side of the connecting rod 37), the valve element 33
And the area of the pressure receiving step surface 65 becomes equal, and the driving of the valve body 33 in the valve opening direction by the refrigerant pressure Pc is completely eliminated by complete cancellation.

If the driving of the valve body 33 in the valve opening direction by the refrigerant pressure Pc is not completely eliminated and the driving of the valve body 33 in the valve opening direction by the refrigerant pressure Pc is to be effectively operated, the valve port 27 is required. Outer diameter D on the larger diameter side of the connecting rod 37 than the diameter Da of
b, and the pressure receiving step surface 65
May be reduced.

Here, since the load of the evaporator (heat exchange) and the temperature (= pressure) of the condenser (radiator) have a proportional relationship in the case of the outside air radiating type, the refrigerant pressure Pc is effectively applied. In the above-mentioned relation, it means that the valve operation superheat degree value is changed (low superheat degree = high refrigerant flow rate at high condenser refrigerant pressure).

As a result, even if a spring made of a shape memory alloy (the first valve closing spring 49 against the valve opening pressure) for which it is difficult to secure a large spring force is used, it can be applied to a high pressure specification. .

(Embodiment 2) FIG. 2 shows a temperature-sensitive expansion valve according to Embodiment 2 of the present invention. In FIG. 2, portions corresponding to those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted.

In this embodiment, the second valve closing spring 5
The first and second valve-opening springs 63 are also made of a shape memory alloy, and each of the valve-closing spring and the valve-opening spring is configured to generate a temperature-sensitive combined spring force.

In this configuration, the second valve closing spring 51 and the second
The second valve-closing spring 5 is made of a shape memory alloy having the same temperature characteristics (temperature-generating force characteristics).
1. By making the temperature-sensitive area of the second valve-opening spring 63 different from the temperature-sensitive area of the first valve-closing spring 49 and the first valve-opening spring 61, the degree of superheat of the refrigerant is kept at a constant value. The temperature range to be maintained can be expanded over a wide range.

FIG. 3 shows the operating characteristics of the temperature-sensitive expansion valve according to the second embodiment. In FIG. 3, the temperature-sensitive valve characteristic 1 corresponds to an evaporation temperature of −20 ° C. to + 20 ° C. In this case, the first valve-closing spring 49 and the first valve-closing spring 49
Act as a reaction force ΔW of the valve-opening spring 61, and the evaporation temperature 0
C. to + 20 ° C., the combined spring of the first valve closing spring 49 and the second valve closing spring 51, the first valve opening spring 61, and the second
Of the combined spring with the valve-opening spring 63. This makes it possible to control a wide evaporation temperature range.

The temperature-sensitive valve characteristic 2 has an evaporation temperature of + 25 ° C.
Another example corresponding to + 45 ° C is shown. Also in this case, it operates as the opposing force ΔW between the first valve closing spring 49 and the first valve opening spring 61.

As described above, the system operates only by the temperature difference and keeps the superheat degree (differential temperature) of the refrigerant at a constant value over the entire operation range without being influenced by the physical properties of the refrigerant (pressure, supercritical region, etc.). Can be kept.

Also in this embodiment, a pressure receiving step surface 65 is provided on the connecting rod 37, and a relatively high refrigerant pressure Pc is applied via the valve port 27 to the valve body as in the first embodiment. 33 acts as a pressure in the valve opening direction and acts on the pressure receiving step surface 65 of the connecting rod 37 as a pressure in the opposite direction (valve closing direction), so that the valve opening pressure actually acting on the valve body 33 is offset. .

(Third Embodiment) FIG. 4 shows a third embodiment of the temperature-sensitive expansion valve according to the present invention. In FIG. 4, portions corresponding to those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof will be omitted.

In this embodiment, a valve closing spring 67 is provided between the spring receiving member 43 and the spring receiving member 47 engaged with the valve body 33 to urge the valve body 33 in the valve closing direction. ,
A valve-opening spring 69 provided between the spring-receiving member 55 and the spring-receiving member 59 to urge the valve body 33 in the valve-opening direction is formed of a bimetallic compression coil spring. Bimetal constituting valve closing spring 67 and valve opening spring 69
Characteristics of bimetals (temperature-generating force characteristics)
Are the same as each other.

By using a bimetal as the temperature-sensitive spring, it is possible to maintain a constant degree of superheat of the refrigerant over a wide area without using a double spring, as shown in FIG. it can.

Also in this embodiment, the connecting rod 37 is provided with the pressure receiving step surface 65, and the first embodiment is different from the first embodiment.
As in the case of (1), the relatively high refrigerant pressure Pc acts on the valve body 33 via the valve port 27 as a pressure in the valve opening direction, and acts on the pressure receiving step surface 65 of the connecting rod 37 in the opposite direction (valve closing direction). Therefore, the valve opening pressure actually acting on the valve body 33 is offset and reduced.

Bimetallic valve closing spring 67, valve opening spring 6
9 is not limited to the coil type, and FIG.
(B) shows the valve-opening springs 69 ', 69 "(the valve-closing springs 67', 6 ').
As shown as 7 ", it may be constituted by a combination of leaf springs. The valve closing spring 67 and the valve opening spring 6
9, the spring shape of the valve closing spring 67 and the spring shape of the valve opening spring 69 are preferably the same so that the bimetals exhibit the same temperature characteristics.

[0061]

As will be understood from the above description, according to the temperature-sensitive expansion valve according to the first aspect of the present invention, the valve body is driven in the valve closing direction in response to the refrigerant temperature at the inlet side of the evaporator. A valve-closing spring made of a temperature-sensitive material, and a valve-opening spring made of a temperature-sensitive material that drives the valve body in a valve opening direction in response to a refrigerant temperature at an outlet side of the evaporator. In the temperature-sensitive expansion valve which operates by the temperature difference between the refrigerant temperature on the inlet side and the refrigerant temperature on the outlet side of the evaporator, in order to reduce or eliminate the refrigerant pressure of the condenser acting on the valve body, the valve The valve stem portion of the body is provided with a pressure receiving surface that receives the refrigerant pressure of the condenser in a direction opposite to a direction in which the pressure acts on the valve body.

Therefore, the refrigerant pressure of the condenser acts on the pressure receiving surface formed on the valve stem portion of the valve body, so that the driving force of the valve body in the valve opening direction or the valve closing direction by the refrigerant pressure of the condenser is reduced. Reduced or lost, it is possible to apply to high pressure specification even if using a spring made of shape memory alloy,
Not only ordinary vapor compression refrigeration cycle, but also CO
_It can also be used for superheat control in the supercritical region or high pressure region in a refrigeration cycle using _two gases.

According to the temperature-sensitive expansion valve according to the second aspect of the present invention, the inlet-side refrigerant passage through which the refrigerant at the inlet of the evaporator flows, the outlet-side refrigerant passage through which the refrigerant at the outlet of the evaporator flows, A valve housing having a valve port formed in the middle of the inlet-side refrigerant passage, a valve body for opening and closing the valve port, and one end fixedly connected to the valve body and the other end of the outlet-side refrigerant passage A connecting rod exposed inside the valve body and the valve housing within the inlet-side refrigerant passage portion of the inlet-side refrigerant passage downstream of the valve port in the flow of the refrigerant from the valve port; A valve closing spring made of a temperature-sensitive material that drives the valve body in the valve closing direction in response to the refrigerant temperature on the inlet side of the vessel, and provided between the connecting rod and the valve housing in the outlet side refrigerant passage. Refrigerant temperature at the outlet side of the evaporator A valve-opening spring made of a temperature-sensitive material that responsively drives the valve body in a valve-opening direction, wherein the connecting rod is configured to control a refrigerant pressure of the condenser acting as a pressure in the valve-opening direction on the valve body. In order to reduce or eliminate the pressure, the pressure receiving step surface is provided to receive the refrigerant pressure of the condenser as the pressure in the valve closing direction.

Therefore, the refrigerant pressure of the condenser acts on the pressure receiving step surface of the connecting rod as the pressure in the valve closing direction, and the refrigerant pressure of the condenser acting as the pressure in the valve opening direction on the valve element reduces the offset.
It is completely canceled and can be applied to high pressure specifications even if a valve closing spring made of shape memory alloy is used, and it can be used not only in a normal vapor compression refrigeration cycle but also in a refrigeration cycle using CO ₂ gas. It can also be used for superheat control in the supercritical or high pressure range.

According to the temperature-sensitive expansion valve according to the third aspect of the present invention, the valve closing spring and the valve opening spring are made of a shape memory alloy.

For this reason, the valve-closing spring and the valve-opening spring are made of a shape memory alloy, so that the required temperature-sensitive spring characteristics can be easily obtained, and the superheat degree can be appropriately controlled.

According to the fourth aspect of the present invention, the valve closing spring and the valve opening spring are made of bimetal.

For this reason, the valve-closing spring and the valve-opening spring are made of bimetal, so that the required temperature-sensitive spring characteristics can be easily obtained, and the superheat control can be appropriately performed over a wide range.

According to the temperature-sensitive expansion valve according to the fifth aspect of the present invention, the temperature characteristic of the valve-closing spring and the temperature characteristic of the valve-opening spring are the same and exhibit a constant differential temperature operation characteristic. did.

Therefore, the temperature characteristics of the valve-closing spring and the temperature characteristics of the valve-opening spring become the same, a constant differential temperature operation characteristic is obtained, and the characteristic curve conforms to the optimum control line and the inflection characteristic calculated by the system efficiency. Control characteristics can be obtained.

According to the temperature-sensitive expansion valve according to the sixth aspect of the present invention, the valve closing spring and the valve opening spring each include a plurality of springs.

For this reason, each of the valve-closing spring and the valve-opening spring is constituted by a plurality of springs, and a predetermined differential temperature operating characteristic is obtained in a wide temperature range based on the combined spring characteristics, and is estimated by the system efficiency. It is possible to obtain a control characteristic suitable for the optimal control line and the inflection characteristic.

According to the temperature-sensitive expansion valve according to the seventh aspect of the present invention, at least one of the valve-closing spring and the valve-opening spring is adjustably screwed to the valve housing. And the initial load (reference load) of the spring can be adjusted.

For this reason, at least one of the valve-closing spring and the valve-opening spring is engaged with the valve housing via an adjusting screw-type spring receiving member which is adjustably screwed to the valve housing to adjust the reference load. The degree of superheat maintained at a constant value can be variably set to a system appropriate value.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a refrigeration / refrigeration cycle apparatus including a temperature expansion valve (Embodiment 1) according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the temperature expansion valve according to the present invention.

FIG. 3 is a graph showing operating characteristics of the temperature expansion valve according to the second embodiment.

FIG. 4 is a sectional view showing one embodiment of a refrigeration / refrigeration cycle apparatus including a temperature expansion valve (Embodiment 3) according to the present invention.

FIG. 5 is a graph showing operating characteristics of the temperature expansion valve according to the third embodiment.

FIG. 6 is a view showing another embodiment of a bimetal valve-opening spring and a valve-closing spring used in the temperature expansion valve according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 3 Condenser 5 Receiver 7 Thermal expansion valve 9 Evaporator 21 Valve housing 23 Inlet port 25 Outlet port 27 Valve port 29 Valve room 31, 31 'Exit side refrigerant passage 33 Valve body 37 Connecting rod 43 Spring receiving member 49 First valve closing spring 51 Second valve closing spring 61 First valve opening spring 63 Second valve opening spring 65 Pressure receiving step surface 67 Valve closing spring 69 Valve opening spring

Claims (7)

[Claims] 1. A valve closing spring made of a temperature-sensitive material for driving a valve body in a valve closing direction in response to a refrigerant temperature on an inlet side of an evaporator, and a valve closing spring made in response to a refrigerant temperature on an outlet side of the evaporator. A valve-opening spring made of a temperature-sensitive material for driving the valve body in a valve-opening direction, wherein the valve-opening spring is operated by a temperature difference between a refrigerant temperature on an inlet side of the evaporator and a refrigerant temperature on an outlet side of the evaporator. In the expansion valve, in order to reduce or eliminate the refrigerant pressure of the condenser acting on the valve element, a direction opposite to the direction in which the refrigerant pressure of the condenser acts on the valve element is applied to the valve stem of the valve element. A temperature-sensitive expansion valve, characterized in that a pressure-receiving surface is provided on the expansion valve. 2. An inlet-side refrigerant passage through which refrigerant on the inlet side of the evaporator flows, an outlet-side refrigerant passage through which refrigerant on the outlet side of the evaporator flows, and a valve port formed in the inlet-side refrigerant passage. A valve housing that opens and closes the valve port; a connecting rod fixedly connected to the valve body at one end and exposed in the outlet-side refrigerant passage at the other end; The valve body is provided between the valve body and the valve housing in the inlet-side refrigerant passage portion on the downstream side of the flow of the refrigerant from the valve port, and is responsive to the refrigerant temperature on the inlet side of the evaporator. A valve-closing spring made of a temperature-sensitive material for driving the valve in the valve-closing direction, provided between the connecting rod and the valve housing in the outlet-side refrigerant passage, and responsive to the refrigerant temperature on the outlet side of the evaporator. Temperature to drive the valve body in the valve opening direction And a postal-made opening spring, the connecting rod, reduces the refrigerant pressure of the condenser which acts as a pressure valve opening direction to the valve body, or to eliminate,
A temperature-sensitive expansion valve having a pressure-receiving step surface for receiving a refrigerant pressure of the condenser as a pressure in a valve closing direction. 3. The temperature-sensitive expansion valve according to claim 1, wherein the valve closing spring and the valve opening spring are made of a shape memory alloy. 4. The temperature-sensitive expansion valve according to claim 1, wherein the valve-closing spring and the valve-opening spring are made of bimetal. 5. The temperature characteristic of the valve-closing spring and the temperature characteristic of the valve-opening spring are the same, and the valve-closing spring and the valve-opening spring are connected by the refrigerant temperature on the inlet side of the evaporator and the refrigerant on the outlet side. The temperature-sensitive expansion valve according to any one of claims 1, 2, 3, and 4, wherein the temperature-dependent expansion characteristic exhibits a constant differential temperature operation characteristic according to a difference from the refrigerant temperature. 6. The temperature-sensitive expansion valve according to claim 1, wherein the valve-closing spring and the valve-opening spring each comprise a plurality of springs. 7. At least one of the valve-closing spring and the valve-opening spring is engaged with the valve housing via an adjusting screw-type spring receiving member that is adjustably screwed to the valve housing, and the spring-loaded member has a spring load. The temperature-sensitive expansion valve according to claim 1, wherein a set value is adjustable.