JP2554541Y2 - Expansion valve - Google Patents

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 controlling a flow rate of a refrigerant entering an evaporator, which is used in a cooling system for an automobile or the like.

[0002]

2. Description of the Related Art An expansion valve of this type generally has a low-pressure chamber which communicates with a refrigerant flow path on the outlet side of an evaporator, and a high-pressure chamber which senses the temperature of refrigerant sent from the evaporator and changes the internal pressure according to the temperature. A chamber is provided, and the two chambers are partitioned by a diaphragm, and a valve mechanism is driven by the displacement of the diaphragm to control the flow rate of the refrigerant sent to the evaporator.

[0003] However, if the displacement stroke of the diaphragm is large, the diaphragm will deteriorate early. Therefore, conventionally, a stopper that prevents further displacement of the diaphragm is provided by limiting the amount of displacement of the diaphragm at the time of heat load that is most frequently used in normal operation, and the heat load more than that causes a low pressure chamber and a high pressure chamber to be separated. Even if the pressure difference increases, the diaphragm remains stopped at the limit position,
The flow rate of the refrigerant is kept constant.

[0004]

[Problems to be solved by the invention] However, when the heat load is very large, especially when the load is high at the time of starting,
There is a problem that the cooling capacity is insufficient and the cooling is poor, and the amount of gas in the refrigerant is large, so that the lubricating oil circulating with the refrigerant is insufficient and the compressor burns.

Therefore, the present invention increases the flow rate of the refrigerant at a high load exceeding a certain limit, such as at the time of starting, without increasing the displacement stroke of the diaphragm at the time of a normal high load, thereby providing sufficient cooling capacity and lubrication capacity. It is an object to provide an expansion valve that can be secured.

[0006]

In order to achieve the above object, an expansion valve according to the present invention senses a low-pressure chamber communicating with a refrigerant flow path on the outlet side of an evaporator, and detects a temperature of a refrigerant discharged from the evaporator. A high-pressure chamber in which the internal pressure changes according to the temperature, a diaphragm that partitions between the low-pressure chamber and the high-pressure chamber, and is displaced following the pressure difference between the low-pressure chamber and the high-pressure chamber; and A valve mechanism driven by the displacement to control the flow rate of the refrigerant sent to the evaporator; and a diaphragm for preventing the displacement of the diaphragm at a position where the low-pressure chamber and the high-pressure chamber reach a predetermined pressure difference. An inverting leaf spring is provided which inverts the diaphragm so that the diaphragm can be displaced beyond the blocking position when the pressure difference between the chamber and the high-pressure chamber becomes larger than a certain value.

[0007]

When the heat load increases and the pressure difference between the low-pressure chamber and the high-pressure chamber reaches a predetermined pressure difference (for example, the most frequently used state), the displacement of the diaphragm is prevented by the reversing leaf spring. Even if the heat load increases to some extent, the flow rate of the refrigerant sent into the evaporator does not change.

However, when the heat load further increases and the pressure difference between the low-pressure chamber and the high-pressure chamber becomes larger than a certain value,
The reversing leaf spring is inverted, so that the diaphragm can be displaced beyond the previous blocking position, and the flow rate of the refrigerant sent into the evaporator sharply increases.

[0009]

An embodiment will be described with reference to the drawings. FIG. 2 shows a refrigeration cycle used for a cooling device of an automobile, and a refrigerant compressed to a high pressure by a compressor 1 driven by an engine releases heat in a condenser 2 to be liquefied to be in a liquid state. The cooled refrigerant (refrigerant liquid) is temporarily stored in the receiver 3.

Then, the refrigerant liquid which has flowed out of the liquid receiver 3 is adiabatically expanded by the expansion valve 10 and enters the evaporator 5, where it absorbs heat, is vaporized, and is returned to the compressor 1. Reference numeral 6 denotes a temperature-sensitive cylinder for controlling the operation of the expansion valve 10.

FIG. 1 shows an expansion valve 10, 14 is a valve body, 11 is a refrigerant inlet connected to the liquid receiver 3 and supplied with high-pressure liquid refrigerant, and 12 is an inlet of the evaporator 5. The refrigerant outlet to be connected.

The inlet side opening of the throttle portion 17 between the refrigerant inlet 11 and the refrigerant outlet 12 is a valve seat, and a ball-shaped valve body 21 is pressed by a compression coil spring 22 so that the throttle portion 17 is moved. It is closed. 23 is an adjusting nut for adjusting the spring pressure of the compression coil spring 22. 20 is
This is a spring receiver interposed between the valve body 21 and the compression coil spring 22.

At the upper end of the valve body 14, there is formed a diaphragm chamber 26 divided into two by a diaphragm 25 made of a flexible thin film displaceable in a direction perpendicular to the surface. The high-pressure chamber 27 of the diaphragm chamber 26 is connected to the temperature-sensitive cylinder 6 provided on the outlet side of the evaporator 5 by a capillary tube 28. The temperature sensing tube 6 senses the temperature of the refrigerant gas exiting the evaporator 5, and a small amount of refrigerant is sealed in the capillary tube 28.
Therefore, the diaphragm chamber 26 changes in accordance with the fluctuation of the temperature of the refrigerant gas exiting the evaporator 5 (caused by the degree of superheat).
The pressure in the high pressure chamber 27 changes.

On the other hand, the low pressure chamber 29 of the diaphragm chamber 26
Communicates with the outlet side of the evaporator 5, and the pressure in the low-pressure chamber 29 is equal to the pressure of the refrigerant gas exiting the evaporator 5. As a result, the diaphragm 25 is displaced by the pressure difference between the high pressure chamber 27 and the low pressure chamber 29.

Numeral 30 designates the movement of the diaphragm 25 as the valve body 2.
1 is an operating rod for transmitting to an actuator. The working rod 30 is
, The upper end thereof contacts the lower surface of a large dish-shaped diaphragm receiver 24 disposed in contact with the lower surface of the diaphragm 25, and the lower end passes through the inside of the throttle unit 17. It passes through and contacts the upper surface of the valve body 21. An O-ring 33 is attached by being urged by a small compression coil spring 34.

With such a configuration, the valve element 21 is displaced through the operation rod 30 in accordance with the displacement of the diaphragm 25, whereby the opening area of the throttle portion 17 is changed.
The amount of the refrigerant sent to the evaporator 5 is controlled.

However, between the back surface of the diaphragm receiver 24 and the valve body 14, an inverting leaf spring 35 formed by a donut-shaped disc spring is disposed. As shown in FIG. 1, this reversing leaf spring 35 has a flat portion 35a near the center, the outside of which is formed in a C-shape, and the peripheral edge of which contacts the valve body 14 side. ing.
Reference numeral 35b is the slope of the C-shape. A small projection 36 is provided on the rear surface of the diaphragm receiver 24 toward the middle of the slope 35 b of the reversing leaf spring 35.

FIG. 3 shows a change in the flow rate of the refrigerant with respect to a change in the pressure difference between the inside of the low-pressure chamber 29 and the inside of the high-pressure chamber 27 (hereinafter simply referred to as "pressure difference") in the expansion valve 10 of the above embodiment. . When the heat load is very small, the pressure difference is small and the diaphragm 25 is not displaced, the throttle portion 17 is completely closed by the valve body 21, and the flow rate of the refrigerant is zero.

However, when the heat load is slightly increased, the diaphragm 25 is displaced downward due to the pressure difference which increases with the heat load, the valve element 21 is separated from the throttle portion 17, and the refrigerant flows into the evaporator 5. Then, as the pressure difference increases, the valve element 21 is separated from the throttle portion 17, and the flow rate of the refrigerant increases.

However, when the pressure difference reaches a predetermined pressure difference (for example, a pressure difference in a thermal load state which is used most frequently in normal use) A, as shown in FIG.
The projection 36 on the rear surface of the diaphragm 25 hits the reversing leaf spring 35, and the diaphragm 25 cannot be further displaced.

The reversing leaf spring 35 is connected to the diaphragm receiver 24.
Even if a force equal to or less than a predetermined value is applied from the side of the projection 36 on the lower surface, it hardly deforms. Therefore, even if the heat load increases to some extent and the pressure difference increases from A, the displacement of the diaphragm 25 is prevented, the state of FIG. 4 is maintained, and the flow rate of the refrigerant is maintained at a constant flow rate C.

However, when the force applied to the reversing leaf spring 35 from the projection 36 on the lower surface of the diaphragm receiver 24 becomes greater than a certain level, as shown in FIG.
5 instantaneously reverses.

Therefore, when the heat load further increases by a certain amount or more from the most frequently used heat load state and the pressure difference reaches B, the reversing leaf spring 35 reverses there and the pressure difference A
In the above state, the diaphragm 25 can be displaced before the stop position where the displacement has been prevented, the valve element 21 moves in the opening direction away from the throttle portion 17, and the flow rate of the refrigerant rapidly increases.

Therefore, when the load is high during normal operation, the stroke of the diaphragm 25 is
However, when the load is higher than a certain limit, such as at the time of starting, the reversing leaf spring 35 is reversed, the diaphragm 25 is largely displaced, and the flow rate of the refrigerant increases.

When the heat load is reduced from such a high load state, due to the characteristics of the reversing leaf spring 35,
As shown in FIG. 3, a hysteresis-like characteristic diagram slightly deviated from that at the time when the thermal load rises is obtained.

[0026]

According to the expansion valve of the present invention, even if the thermal load is increased to a certain extent, the displacement of the diaphragm is prevented by the reversing leaf spring. It can prevent the diaphragm from deteriorating, and when the load exceeds a certain limit that occurs at the time of starting, etc., the reversing leaf spring reverses, the flow rate of the refrigerant increases, and sufficient cooling capacity and lubrication performance are obtained. Has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an expansion valve according to an embodiment.

FIG. 2 is a schematic view of a refrigeration cycle of an embodiment.

FIG. 3 is a diagram showing a refrigerant flow rate characteristic of the embodiment.

FIG. 4 is a partial sectional view showing the operation of the expansion valve according to the embodiment.

FIG. 5 is a partial sectional view showing the operation of the expansion valve according to the embodiment.

[Explanation of symbols]

 5 evaporator 21 valve body 25 diaphragm 27 high-pressure chamber 29 low-pressure chamber 30 operating rod 35 reversing leaf spring

Claims (1)

(57) [Scope of request for utility model registration] A low-pressure chamber communicating with an outlet-side refrigerant flow path of an evaporator; a high-pressure chamber that senses a temperature of a refrigerant sent from the evaporator and changes an internal pressure according to the temperature; A diaphragm that partitions between the high-pressure chamber and displaces following the pressure difference between the low-pressure chamber and the high-pressure chamber; and a valve mechanism that controls the flow rate of the refrigerant that is driven by the displacement of the diaphragm and sent to the evaporator. And preventing the displacement of the diaphragm at a position where the low-pressure chamber and the high-pressure chamber reach a predetermined pressure difference, and furthermore, when the pressure difference between the low-pressure chamber and the high-pressure chamber becomes larger than a certain value, the diaphragm An expansion valve provided with a reversing leaf spring that reverses so as to be displaceable beyond a blocking position.