JPH039183A - Temperature type expansion valve - Google Patents

Abstract

PURPOSE:To obtain a temperature-type expansion valve of a small size, which can correspond to a substantial change in a load without generating any trouble or the like due to a jam of dust, by incorporating a spring unit, having the inversion characteristic with an action point adjustable, in a temperature-sensing action mechanism and providing a throttle mechanism which functions as an expanding device of a large flow amount in a valve-open position. CONSTITUTION:A valve seat 1c is provided in a partition between a primary chamber 1a and a secondary chamber 1b in a valve main unit 1, and a needle valve 2 is urged toward the valve seat 1c by a valve spring 3. While a diaphragm 4, supported by an action spring 5, receives a pressure in a pressure chamber 6 to actuate a connecting rod 7, and its movement is transmitted to the valve unit 2 with opening of the valve determined. Further in the action spring 5, a position of a spring receiver 5a is moved through an adjusting rod 10a by moving a top end wedge-shaped action point-setting unit 10, and an action point of the diaphragm 4 is adjusted. Also the diaphragm 4 has the inversion characteristic, and when a difference between pressures in a pressure chamber 6 and in the secondary chamber 1b exceeds a preset value, the diaphragm, which completely open-separates the valve unit 2 from the valve seat 1c by snapping action, makes action of an expanding device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an expansion valve used in a small-sized refrigeration system, and more particularly to an expansion valve used in a refrigeration system in which the load fluctuates significantly.

[Conventional technology]

Capillaries are often used as expanders in small refrigeration devices built into household refrigerators, vending machines, and the like because they require a very small flow rate of refrigerant. However, capillaries have the drawback of not being able to adequately respond to load fluctuations.

On the other hand, a thermostatic expansion valve can respond to load fluctuations, but it has a small capacity suitable for small refrigeration equipment, and in order to have high reliability, it requires a valve seat and a needle valve for it. It is necessary to make the shape of the valve body extremely precise and to prevent the pressure force of the valve body against the valve seat from becoming excessive. However, a valve with such a precise structure has the disadvantage that it is easily clogged with dirt, and reliability cannot be maintained unless a precise strainer or the like is provided.

[Problem to be solved by the invention]

Under the circumstances mentioned above, we have developed a temperature-type refrigeration system that has a size that is suitable for small refrigeration equipment, has the ability to handle large fluctuations in load, and does not require a particularly precise strainer or the like to cause malfunctions due to dirt clogging. It is an object of the present invention to provide an expansion valve.

[Means to solve the problem]

The object of the present invention is as follows: - A valve body is slidably provided in a primary room and is biased in the valve closing direction by a valve spring against a valve seat provided on a partition wall between a classroom and a secondary room; In an expansion valve in which a connecting rod that can penetrate a valve seat from the secondary side and push the valve body in the valve opening direction is combined with a temperature-sensitive actuation mechanism, the temperature-sensitive actuation mechanism has a reversal characteristic. This is achieved by a thermostatic expansion valve which is characterized in that it incorporates a spring body whose operating point can be adjusted and is equipped with a throttle mechanism that functions as a large flow expander in the valve open position.

The temperature-sensitive actuation mechanism used in the thermostatic expansion valve of the present invention includes, for example, a temperature sensor containing a temperature-sensitive medium and a pressure-responsive body such as a diaphragm that receives the pressure of the temperature sensor. As the pressure-responsive body, one that is supported against the pressure of the temperature-sensitive medium by a spring body that reverses its operation according to a change in load can be used. In this case, the pressure-responsive body itself, such as a diaphragm, may have a spring function and, in addition, may have a reversal characteristic. Such a temperature-sensitive actuation mechanism causes only a small displacement below a predetermined temperature, but is adjusted so that when a predetermined temperature is reached, the spring body reverses its operation and produces a large displacement. If it has, it can be used without any restriction on its structure.

The throttling mechanism in the thermostatic expansion valve of the present invention may be formed between the valve seat and the valve body as in conventional expansion valves, but may also be provided in the flow path following the valve seat, or It may also be formed in the middle of the fluid passage within the other valve body. The flow rate limited by such a restricting mechanism is preferably selected to match the maximum flow rate expected in the refrigeration circuit to which the thermostatic expansion valve of the present invention is installed.

[For production]

The thermostatic expansion valve of the present invention not only performs control operations using the same functions as ordinary thermostatic expansion valves, but also controls the refrigerant compression when the degree of superheating of the refrigerant gas increases due to an increase in the heat load of the refrigeration circuit. This is detected by a temperature-sensitive tube installed on the suction side of the machine, and the snapping action moves the valve body to its maximum opening position, allowing the maximum flow rate of refrigerant limited by the throttle mechanism to pass through. When the degree of superheat of the refrigerant gas returns to normal, the valve body returns to the normal control state again by snapping operation.

Furthermore, when the thermostatic expansion valve of the present invention is incorporated into a refrigeration circuit such as a refrigerator, each time the compressor is turned on and off during operation of the refrigerator, the refrigerant gas that is highly superheated at the time of startup is returned to the suction of the compressor. When detected by the valve seat, the valve body automatically moves to the maximum opening position to increase the flow rate of refrigerant and remove any debris caught in the valve seat. In addition, normally, when the refrigerant is clogged with dirt, the flow rate of the refrigerant decreases, causing an imbalance between the heat load and the refrigerant flow rate.However, the thermostatic expansion valve of the present invention reduces the degree of superheating of the return refrigerant gas that occurs in such cases. Detects the rise in the temperature and operates in the same manner as described above, and after automatically clearing the dirt clogging, returns to the normal control state.

〔Example〕

An example of the thermostatic expansion valve of the present invention is shown in FIG. In the figure, 1 is a valve body, and a valve seat IC is provided on a partition wall formed between a classroom 1a and a secondary room lb. - A valve body 2 having a needle-shaped tip is loosely fitted in the classroom la, and is biased toward the valve seat IC by a valve spring 3.

On the other hand, 4 is a diaphragm supported by an actuating spring 5, which actuates a connecting rod 7 by receiving pressure in a pressure chamber 6 that communicates with a temperature-sensitive cylinder (not shown) through a thin tube, for example. There is. The tip of this connecting rod 7 is formed to have a thickness that allows it to pass through the valve seat IC leaving a flow gap 8 for the refrigerant, and is configured so that it can come into contact with and push the tip of the valve body 2. be. Therefore, the movement of the diaphragm 4 is transmitted to the valve body 2 via the connecting rod 7, and the opening degree of the valve is determined. Note that 9 is a pressure equalizing hole for guiding the pressure inside the secondary chamber lb to the lower surface side of the diaphragm 4.

The operating spring 5 is configured so that the magnitude of the compressive force can be changed by moving the operating point setting body 10, which has a wedge-shaped tip, to move the position of the spring receiver 5a via the adjustment rod 10a. This allows the operating point of the diaphragm 4 to be adjusted.

The diaphragm 4 in the expansion valve of this example has a reversal characteristic, and snaps when the difference between the pressure in the pressure chamber 6 and the pressure in the secondary chamber lb exceeds a set value. The valve body 2 is completely separated from the valve seat lc.

At this time, the flow gap 8 functions as a refrigerant throttling mechanism and functions as an expander capable of handling a large flow rate. However, until the difference between the pressure in the pressure chamber 6 and the pressure in the secondary chamber lb reaches the set value, the diaphragm 4 is continuously displaced in response to pressure changes, and the actuation spring 5 is slightly compressed. At the same time, the valve body 2 is floated above the valve seat IC to function as a normal proportional control type expander corresponding to a small flow rate.

An example of the operating characteristics of the thermostatic expansion valve of the present invention is shown in FIG. 2 as a graph of the relationship between the degree of superheating of the refrigerant gas on the suction side of the compressor and the degree of valve opening.

〔Effect of the invention〕

The temperature-type expansion valve of the present invention is capable of highly accurate flow control even when the flow rate of refrigerant is low, and the temperature-sensitive actuation mechanism includes a spring body with reversal characteristics that allows adjustment of the operating point. Because it is built into the refrigerant, it has the advantage of being able to supply a large amount of refrigerant even if the heat load increases rapidly.

Furthermore, when the refrigeration equipment starts operating, it detects that high-temperature refrigerant gas is returning to the compressor, supplies a large amount of refrigerant, and removes debris, etc. If a blockage occurs even then, there will be a shortage of refrigerant supply. It has the advantage of being less susceptible to damage caused by debris, such as by detecting an increase in the degree of superheating of the refrigerant gas and automatically removing debris.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view of an example of the thermostatic expansion valve of the present invention, and FIG. FIG. 2 is a graph showing an example of the operating characteristics of the thermostatic expansion valve of the present invention. 1... Valve body, IC... Valve seat, 2... Valve body, 3...
...Valve spring, 411. Diaphragm, 5... Operating spring, 5a... Spring receiver, 6... Pressure chamber, 7... Connecting rod, butt... Distribution gap, 9... Equalizing hole, 10... Operating point Setting body, 10a...adjustment rod.

Claims (1)

[Claims] A valve element, which is biased in the valve closing direction by a valve spring against a valve seat provided on a partition wall between a primary chamber and a secondary chamber, is slidably provided in the primary chamber, and the valve element is inserted through the valve seat from the secondary side. In the expansion valve, a connecting rod is combined with a temperature-sensitive actuation mechanism to push the valve body in the valve-opening direction. 1. A temperature-type expansion valve characterized by having a throttle mechanism incorporated therein and functioning as a large-flow expander in the valve open position.