JPH09133435A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expansion valve to control a flow rate of a refrigerant with high precision according to the fluctuation of a cooling load and prevent the occurrence of the trouble and breakage of a compressor. SOLUTION: In an expansion valve to control a flow rate of a refrigerant by the area of a flow passage comprising a valve set 46 and a valve element 100, the expansion valve is formed in such a manner that a plurality of seal surfaces 101 and 102 having different gradients at which the change gradient of a refrigerant flow rate is changed to a valve lift amount from full closing of the valve body 100 to full opening are formed on the seal surface of the valve seat 46 or the valve element 100. This constitution automatically changes a change ratio of a refrigerant flow rate when a lift amount exceeds a given value, and provides a flow rate of a refrigerant responding to a cooling load through simple structure.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A receiver type refrigeration cycle used for an air conditioner or the like has conventionally been provided with a compressor 1, a condenser 2, a receiver 3, an expansion valve 4 and an evaporator 5 as shown in FIG. It constitutes a cycle that flows in the above order.

That is, the gaseous refrigerant is the compressor 1
At high temperature and high pressure, it is sent to the condenser 2, and the high temperature and high pressure gaseous refrigerant is forcibly cooled by the outside air being blown by the fan or the like in this condenser 2. For this reason, the latent heat of condensation of the refrigerant gas is taken by the cooling air, and the refrigerant gas is liquefied. Then, it is supercooled while flowing through the condenser 2.

The high-pressure refrigerant liquefied by the condenser 2 is sent to the receiver 3 and decompressed by the receiver 3. The decompressed liquid refrigerant is rapidly expanded when the expansion valve 4 is opened to become a low-pressure low-temperature liquid refrigerant, and the liquid refrigerant is sent to the evaporator 5. While the liquid refrigerant entering the evaporator 5 flows in the tube of the evaporator 5,
The latent heat required for evaporation is taken from the ambient air through the fins to actively evaporate, thereby cooling the ambient air and cooling the room.

The refrigerant atomized by the evaporator 5 is returned to the compressor 1, heated again to high temperature and high pressure, and sent to the condenser 2. By repeating the refrigerant refrigeration cycle as described above, the refrigerant takes heat from the indoor air by the evaporator 5 to cool the indoor air, and the heat is discharged to the outside air via the condenser 2.

In the air conditioner as described above, the expansion valve 4
The flow rate of the refrigerant is controlled by, and the refrigerant at the outlet of the evaporator 5 is controlled so as to maintain an appropriate degree of superheat (superheat). That is, the refrigerant flowing through the evaporator 5 is superheated to such an extent that the evaporator 5 completely completes the evaporation, so that the liquid refrigerant is not returned to the compressor 1.

An example of such an expansion valve 4 is shown in FIG.
The temperature type expansion valve shown in FIG. 2 is used, and this temperature type expansion valve is provided with a diaphragm 41 in the expansion valve main body 40, and the diaphragm 41 has a pressure chamber 42 and a pressure equalizing chamber 43 in the expansion valve main body 40. It is divided into The pressure equalizing chamber 43 is connected to the outlet of the evaporator 5 via a pipe (not shown), and the refrigerant gas pressure of the evaporator 5 is introduced into the pressure equalizing chamber 43.

A valve rod 44 is connected to the diaphragm 41, and a valve element 45 is attached to the valve rod 44. The valve body 45 is adapted to come into contact with and separate from the valve seat 46, and the valve seat 46 has a valve hole 46a whose opening degree is changed by the valve body 45. The valve hole 46a is the receiver 3
Is formed between the inlet connection pipe 47 connected to the above and the outlet connection pipe 48 connected to the evaporator 5. A return spring 49 is connected to the valve body 45.
Receives the urging force of the return spring 49 and is always in the valve seat 4
6, a force in the valve closing direction is received.

A temperature sensitive tube 50 is connected to the pressure chamber 42 via a thin tube 51. The temperature-sensitive cylinder 50 contains an inert gas and an adsorbent 52 that adsorbs the inert gas according to the temperature.

The temperature sensitive cylinder 50 is installed at the outlet of the evaporator 5 and detects the temperature of the refrigerant at the outlet of the evaporator 5. In the expansion valve 4 having such a configuration, when the superheat degree of the refrigerant at the outlet of the evaporator 5 becomes equal to or higher than a predetermined value, the temperature of the adsorbent 52 housed in the temperature sensitive tube 50 rises to release the inert gas, and the temperature sensitive The gas pressure in the cylinder 50 is increased. This gas pressure is transmitted through the thin tube 51 to the expansion valve body 40.
Is transmitted to the pressure chamber 42, and the gas pressure in the pressure chamber 42 rises. This gas pressure pushes the diaphragm 41, and when the sum of the refrigerant gas pressure in the pressure equalizing chamber 43 and the urging force of the return spring 49 is overcome, the valve body 45 is pushed down via the valve rod 44. From this, the valve body 45 separates from the valve seat 46,
The valve hole 46a is opened. Therefore, the refrigerant of the receiver 3 is sent out to the evaporator 5 through the inlet connection pipe 47, the valve hole 46a, and the outlet connection pipe 48, and the flow rate of the refrigerant flowing through the evaporator 5 increases. This makes it possible to reduce the degree of superheat of the refrigerant at the outlet of the evaporator 5 to a predetermined value or less.

On the contrary, when the degree of superheat of the refrigerant at the outlet of the evaporator 5 becomes equal to or lower than a predetermined value, the adsorbent 52 adsorbs the inert gas and lowers the gas pressure in the temperature sensing tube 50, whereby the pressure chamber 4
The gas pressure of 2 is reduced to bring the valve element 45 closer to the valve seat 46 side.
Therefore, the opening degree of the valve hole 46a is narrowed and the amount of the refrigerant sent to the evaporator 5 is reduced. Therefore, the degree of superheat of the refrigerant at the outlet of the evaporator 5 can be increased to a predetermined value or more.

By the way, in the expansion valve 4 having the above-mentioned function, the conventional valve body 45 has a spherical shape as shown in FIG. In addition, 45a is a valve body receiver. In the case of the spherical valve body 45 as described above, the refrigerant flow rate changes substantially linearly with respect to the valve lift amount with which the valve body 45 moves away from the valve seat 46, as shown in the characteristic diagram of FIG. Characteristic B in FIG. 6 is characteristic A
The characteristics of the expansion valve with a large flow rate are shown in comparison with those of (1) and (3), and can be obtained by increasing the diameter of the spherical valve body.

[0013]

However, in an air conditioner for a vehicle, for example, when the cooling load becomes large while the vehicle is traveling at high speed, the evaporator 5 actively evaporates the refrigerant, so that the evaporator outlet portion. The superheat degree of the refrigerant is increased, and a large amount of refrigerant flow is required. However, the expansion valve having the characteristic A shown in FIG. 6 cannot supply a sufficient amount of refrigerant. Therefore, it is required to use the expansion valve of characteristic B.

On the other hand, in the expansion valve of the characteristic B, when the cooling load is lower than the rated load, the refrigerant flow rate becomes excessive, the superheat degree of the refrigerant becomes small, and hunting or the like easily occurs. Is slightly lower than that of the expansion valve of characteristic A. Further, in the case of the expansion valve having the characteristic B, the flow rate of the refrigerant becomes excessive and the liquid is likely to return when the compressor is started,
This will cause damage to the compressor. Therefore, it is desirable to use the expansion valve having the characteristic A at the time of starting the compressor or in the operating range from the light load to the rated load.

Therefore, the object of the present invention is to
From the light load of the cooling load to the high load, it is possible to control the flow rate of the refrigerant appropriately according to the change of the load, prevent the superheat degree from becoming excessive, and prevent the compressor from malfunctioning or being damaged. To provide.

[0016]

In order to achieve the above object, the invention of claim 1 is an expansion valve for controlling a refrigerant flow rate by a flow passage area formed by a valve seat and a valve body. And at least one of the sealing surfaces of the valve body is formed with a plurality of sealing surfaces having different gradients in which the gradient of the refrigerant flow rate changes with respect to the valve lift amount from the fully closed to the fully opened state of the valve body. It is an expansion valve characterized by that.

According to the first aspect of the invention, when the valve body is seated on the valve seat and moves in the direction away from the valve seat from the state in which the valve hole is closed, the change ratio of the gap between the valve body and the valve seat is changed. Changes according to the seal surfaces having different slopes, and a lift region in which the refrigerant flow rate changes gradually and a lift region in which the refrigerant flow rate changes rapidly are formed. Therefore, the change rate of the refrigerant flow rate can be changed in the middle of the valve list.

According to a second aspect of the present invention, the plurality of sealing surfaces are formed by at least two sealing surfaces having different slopes, a slope corresponding to a light load to a rated load region and a slope corresponding to a high load region. The expansion valve according to claim 1, wherein:

According to the second aspect of the invention, when the valve body is seated on the valve seat and moves in the direction away from the valve seat from the state in which the valve hole is closed, the change in the refrigerant flow rate is moderate in the region where the lift amount is small. Therefore, it is possible to obtain a refrigerant flow rate corresponding to the rated load range from a light load, and when the lift amount exceeds the rated load range, the change in the refrigerant flow rate becomes abrupt and the refrigerant flow rate corresponding to the high load range is secured. You can

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on an embodiment shown in FIGS. 1 and 2. This embodiment shows an example applied to the temperature type expansion valve 4 used in the refrigeration cycle shown in FIGS. 3 and 4, and the members which may be the same as those shown in FIGS. 3 and 4 are designated by the same reference numerals. The description is omitted.

FIG. 1 shows only the portion of the expansion valve of this embodiment different from the conventional one.
Is a valve body. The valve body 100 has a substantially conical shape, and a gently sloping portion 101 and a steeply sloping portion 1 are provided on the sealing surface on the peripheral side surface.
02 is formed and has a two-step gradient.

The valve body 100 is connected to the diaphragm 41 shown in FIG. 4 via the valve rod 44. A spring seat 103 is formed on the valve body 100, and an upper end of a return spring 49 is in contact with the spring seat 103.

The operation of the embodiment having such a configuration will be described. When the gas pressure of the heat-sensitive cylinder 50 changes according to the degree of superheat of the refrigerant at the outlet of the evaporator 5 from the state where the valve body 100 abuts the valve seat 46 and closes the valve hole 46a, the gas pressure responds to this gas pressure. When the diaphragm 41 is actuated and the valve rod 44 is pushed downwards by this, the valve body 100 moves to the valve seat 4
6 and the valve hole 46a is opened.

In the operating range from a light load to a rated load where the lift amount of the valve body 100 is small, the opening area between the valve body 100 and the valve seat 46 is dominated by the gently sloping seat surface of the gently sloping portion 101. Therefore, the rate of change of the opening area of the valve hole 46a with respect to the lift amount of the valve body 100 is relatively gradual, and as shown in FIG.

In a large operating range in which the lift amount of the valve body 100 exceeds the rated load, the opening area between the valve body 100 and the valve seat 46 is governed by the steeply inclined seat surface of the steep slope portion 102.
For this reason, the rate of change of the opening area of the valve hole 46a with respect to the lift amount of the valve body 100 rapidly changes, so that the refrigerant flow rate also changes rapidly as shown in FIG. 2B.

According to this structure, in the operating range from the light load to the rated load, the change in the refrigerant flow rate is gradual, so that the refrigerant flow rate does not become excessive. Therefore, the degree of superheat of the refrigerant at the outlet of the evaporator 5 is high. It is possible to prevent the deterioration of the cooling performance due to the decrease in the degree of superheat. Further, since the flow rate of the refrigerant does not become excessive, it is possible to prevent the liquid from returning when the compressor 1 is started.

In a large lift amount range exceeding the rated load, the change rate of the refrigerant flow rate becomes abrupt and the refrigerant flow rate can be increased. As a result, for example, when the automobile travels at high speed, the compressor 1 rotates at high speed and the refrigerant flow rate can be significantly increased under operating conditions in which the cooling load is large. Therefore, it is possible to prevent the refrigerant superheat degree at the outlet of the evaporator 5 from increasing and prevent the compressor 1 from overheating.

Therefore, the flow rate characteristic can be automatically switched by one expansion valve, and the structure is simple and
Since the movement of the valve body 100 is also simple, a reliable operation is performed, and the flow rate characteristics can be reliably switched.

In the above embodiments, the temperature type expansion valve of the present invention is applied to the refrigeration cycle of the vehicle air conditioner, but the expansion valve of the present invention can be applied to various refrigeration cycles.

[0030]

As described above, according to the first aspect of the present invention, when the predetermined lift amount is exceeded, the rate of change of the refrigerant flow rate automatically changes, and the refrigerant having a simple structure and adapted to the cooling load is obtained. The flow rate can be obtained.

According to the second aspect of the present invention, the change of the refrigerant flow rate becomes gentle in the region where the lift amount is small, and the refrigerant flow amount corresponding to the rated load region can be obtained from the light load, and the lift amount is the rated load. When it exceeds the range, the change of the refrigerant flow rate becomes rapid, and the refrigerant flow rate corresponding to the high load area can be secured. Therefore, the refrigerant flow rate can be automatically set according to the cooling load, and overheat failure of the compressor can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a valve body portion of a thermal expansion valve showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a valve lift amount and a refrigerant flow rate using the temperature type expansion valve of the embodiment.

FIG. 3 is a configuration diagram showing a refrigerating cycle of a vehicle air conditioner using the present invention and a conventional temperature type expansion valve.

FIG. 4 is a diagram showing the entire structures of the present invention and a conventional thermal expansion valve.

FIG. 5 is a configuration diagram of a valve body portion of a conventional temperature type expansion valve.

FIG. 6 is a characteristic diagram showing a relationship between a valve lift amount and a refrigerant flow rate using a conventional thermal expansion valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Condenser 3 ... Receiver 4 ... Expansion valve 5 ... Evaporator 40 ... Expansion valve main body 41 ... Diaphragm 42 ... Pressure chamber 46 ... Valve seat 46a ... Valve hole 50 ... Temperature sensing cylinder 100 ... Valve body 101 ... Gradient part 102 ... steep slope

Claims (2)

[Claims] 1. An expansion valve for controlling a refrigerant flow rate according to a flow passage area formed by a valve seat and a valve body, wherein at least one of the sealing surfaces of the valve seat and the valve body has a sealing surface of the valve body. An expansion valve comprising a plurality of sealing surfaces having different gradients in which a gradient of a refrigerant flow rate varies depending on a valve lift amount from a fully closed state to a fully opened state. 2. The plurality of sealing surfaces are formed by at least two sealing surfaces having different slopes, a slope corresponding to a light load to a rated load region and a slope corresponding to a high load region. The expansion valve according to Item 1.