JPS5810055Y2 - temperature expansion valve - Google Patents

Description

[Detailed description of the invention] This invention relates to a thermostatic expansion valve that always maintains a constant supply of refrigerant for the same degree of superheat in any season throughout the year. Applicable to thermostatic expansion valves that are used continuously under conditions where the ambient temperature fluctuates widely, such as during summer and winter.

In refrigeration equipment, the evaporation pressure does not change much depending on the ambient outside temperature and is almost constant, but the condensing pressure changes significantly in relation to the condensing temperature. This results in condensation pressure several times higher in summer than in winter.

If the opening degree of the expansion valve is constant, the flow rate will increase due to a large pressure difference, so if the expansion valve is designed to suit summer characteristics, in winter it will not reach the maximum value corresponding to the predetermined maximum degree of superheat. Even if the valve opening is indicated, the amount of refrigerant that passes through will be too small, so if it is used continuously in an environment where the ambient temperature fluctuates widely depending on summer and winter, or day and night, etc. However, there is a problem in that a change in ambient temperature causes a difference in the amount of refrigerant passing through a constant valve opening, and this must be corrected.

For this reason, in an expansion valve designed for use in winter when the condensing pressure is low, a second throttle point is provided in series with the first throttle point.
In the summer when the condensing pressure is high, the second throttling point is designed to exert a strong throttling action, and the first throttling point is designed to match the predetermined degree of superheating when the condensing pressure is low. 53-13252.

An overview of this conventional invention will be explained with reference to FIG.
0, a first throttle point 41 and a second throttle point 42 are connected directly one after the other.

The first throttle point is delimited by a valve seat 43 and a bowl-shaped closure 44 .

The second throttle point 42 is formed by a valve seat 45 and a part of a piston-shaped adjusting element 47 which is designed as a throttle body 46 .

A pot-shaped closure 44 is fixed to an extension 48 of a valve stem 49.

In the bottom of the closure body 44 there is an opening 50 by which the chamber in front of the first throttle point is connected to the closure body 44 and the adjustment member 4.
The adjustment member 47 is made of plastic and has a sealing lip 52 for sealing the chamber 51.

The comparison spring 52a rests on the one hand on the adjusting element 47 and on the other hand on the connecting surface 53 which is connected to the valve stem 49 and thus to the closing body 44.

The first throttle point 41, which also closes the valve, is located on the diaphragm 3.
1.

This movement is also followed by the adjusting element 47, so that the second throttle point can also be changed.

Due to the presence of the hole 50, the condenser pressure acts on the chamber 51, and the adjusting member 47 compares the pressure difference between the condensing pressure and the evaporation pressure with the pressure of the condenser 52.
loaded by a.

Therefore, due to the condensation pressure, the adjusting member 47
is adjusted to a predetermined relative position with respect to the second
The constriction point of is modified as a function of the pressure.

By the way, in the structure of this expansion valve, the first and second throttle points are formed by two valve seats and the inclined surfaces of the first and second valve bodies that face them. A space with a large flow path cross-sectional area is formed between the throttle points, and the refrigerant passing through the expansion valve is expanded and depressurized in the above space after passing through the first throttle point, and this N generates flash gas. , the gas-entrained refrigerant passes through the second throttling point.

The amount of flash gas generated depends on the degree of supercooling of the refrigerant, and the degree of supercooling changes depending on the quality of heat exchange in the condenser due to outside temperature, wind, fan operating conditions, etc. If the degree of supercooling is small, A small vacuum generates flash gas.

Therefore, depending on the change in the degree of supercooling, the refrigerant with a different amount of gas mixed in will be adjusted at the second throttling point.
Even if the flow rate that passes through the expansion valve is adjusted as described above based on the difference between the condensing pressure and the evaporation pressure, there is a problem in that the flow rate that passes through the expansion valve fluctuates depending on the amount of flash gas generated due to changes in the degree of supercooling.

The technical problem to be solved by the present invention is to prevent the space that expands and depressurizes from being formed between the first throttle and the second throttle.

The technical means of the present invention taken to solve this technical problem are as follows.

(a) The throttle valve seat is a flat valve seat that is perpendicular to the valve seat passage, and (b) The surface of the first valve body that operates depending on the degree of superheating that faces the throttle valve seat is parallel to the valve seat surface. , ←→ A second valve body having a needle portion at its tip for flow rate adjustment is slidably accommodated in the first valve body, the needle portion at the tip of the second valve body is made to protrude into the valve seat, and the valve The seat passage is a cylindrical passage, and (b) condensation pressure is applied to the back surface of the second valve body, evaporation pressure is applied to the front face of the second valve body through the center guide hole of the second valve body, and A spring that urges the second valve body to retreat into the first valve body, and a first valve that restricts movement of the second valve body toward the valve seat at a predetermined position using a differential pressure between condensation pressure and evaporation pressure. The second valve body is provided with a stepped portion that engages with the body.

The above technical means works as follows.

When the pressure difference between the condensation pressure and the evaporation pressure becomes larger than the predetermined pressure expressed by the spring, such as in summer, the second valve body is pushed toward the valve seat against the spring, and the engagement stage is pushed out. occupies a predetermined position where it is stopped.

At this time, the cross-sectional area of the second throttle formed between the second valve body and the valve seat is smaller than the cross-sectional area of the first throttle formed between the first valve body and the valve seat, and is continuous. The space does not exist between the two throttles and the refrigerant flows into the second throttle without expanding.
The flow rate is adjusted by the valve body, and the first valve body is no longer involved in adjusting the flow rate.

This will be further explained based on the opening characteristic diagram shown in FIG. 5 which shows the relationship between the valve lift and the valve opening area.

In other words, the line A in the figure is the opening characteristic diagram of the first valve body, and the line at the opening is the opening characteristic diagram of the second valve body.

If the pressure difference between the condensation pressure and the evaporation pressure is greater than the predetermined pressure, the opening of the line A is larger than the opening of the opening, so the flow rate is adjusted according to the characteristics of the opening.

When the condensing pressure decreases in winter and the pressure difference between it and the evaporating pressure becomes less than a predetermined pressure, the second valve body is moved by the spring to close the first valve body.
It retreats into the valve body, and the small-diameter portion of the needle at the tip protrudes into the valve seat, expanding the flow path, and the opening characteristic of the second valve body becomes C. In the range up to the lift a of the first valve body, The opening of the first valve body is smaller than the opening of the second valve body, and is continuous with both openings.The flow rate adjustment follows the opening characteristic A of the first valve body, and at this time, the second valve body adjusts the flow rate. not be involved.

Since the refrigerant flows from the first throttle to the second throttle, which is slightly larger than the first throttle, there is little change in pressure and it is difficult to generate flash gas, but even if gas is generated at the first throttle, the second throttle
Since there is no throttling, there is no fluctuation in the flow rate in the evaporator unless the flow rate is adjusted by the first restrictor.

When the lift of the first valve body exceeds point a in the figure, the opening of the first valve body becomes larger than the opening of the second valve body, and the flow rate is adjusted according to the opening characteristic of the second valve body as the condensing pressure decreases. becomes large, and for example, in the riff l-1, the opening area becomes b.

The flow of the refrigerant in the range of opening characteristic C continuously flows from the first aperture to the second aperture which is smaller than the first aperture, and therefore does not expand.

The present invention produces the following unique effects.

Since the present expansion valve does not throttle the flash gas-containing refrigerant, it has the effect of significantly reducing the valve squealing phenomenon that occurs when the gas-containing refrigerant passes through the throttle point of the conventional expansion valve.

Hereinafter, an illustrated embodiment will be described to show a specific example of the above-mentioned technical means.

FIG. 1 shows a broken sectional view of an external pressure equalization type expansion valve, and FIG. 2 shows a partially enlarged sectional view of the main parts.

The valve body 1 has a refrigerant inlet A and an outlet B, and both ports A,
A first valve body 3 that opens and closes a flat valve seat 26 of a communicating throttle hole 2 communicating with B is slidably provided on the inner wall of the valve body, and a surface 3a of the first valve body facing the valve seat 26 is It is parallel to the valve seat surface.

A pressure responsive part C is provided at the upper end of the valve body, and includes a diaphragm 4, an upper cover 7, and a cover 8 that is coupled to the valve body. A saturation pressure P1 of the sealed gas corresponding to the temperature of the temperature sensing part 10 is introduced through the capillary tube 9, and the operation of the diaphragm 4 is controlled by the first valve A valve rod 11 is provided for transmitting the pressure to the body 3, and an equalizing pipe 13 for transmitting the pressure P6 at the outlet of the evaporator is opened in the chamber 6.

On the lower surface of the first valve body 3, a superheat degree adjusting spring 14 always biases the first valve body 3 in the closing direction with a set elasticity P1, and an adjusting screw 15 that adjusts the elasticity of the spring 14 is attached to the valve body. The above structure operates a normal temperature variable expansion valve that adjusts the opening degree of the first valve body 3 against the spring 14 by changing P1P6-△P (degree of superheat). It is.

The first valve body 3 has a stepped hollow cylindrical shape with both ends open, and the tip of the small diameter portion forms a flat plate 3a that opens and closes the flat valve seat 26 of the communicating throttle hole 2 depending on the change in the degree of superheat, and the tip of the large diameter portion The opening opening is fixed to the spring receiver 18 of the adjustment spring 14 by welding the periphery thereof, and a bellows 20 with one end fixed to the spring receiver 18 is provided in the valve inner chamber 17. has a threaded portion 21a that is fixed to the free end of the bellows, passes through the bellows longitudinally, and has one end protruding outside the bellows to be connected to a second valve body needle valve 23, which will be described later, and the other end is attached to the spring receiver 18. A rod 21 is provided to screw a spring receiver 24 that penetrates and is inserted into the spring 14, and the rod 21 is always connected to the spring 22 interposed between the spring receiver 18 and the spring receiver 24. It is biased downward.

Alternatively, the spring bearing 18 is provided with a small hole 19 that communicates with the inside of the bellows 20 and the primary side (inlet A side) of the outside of the valve inner chamber.

The head of the rod 21 is provided with a second valve body needle valve 23 which is threadedly connected to the threaded part 21a and slid into the center hole 16 of the small diameter part, and one end of the needle valve 23 is connected to the secondary side (outlet B). side)
It has a central guide hole 25 whose other end opens into the valve inner chamber 17, and a stepped portion 23a that engages with the inner wall of the valve body 3 to prevent the needle valve 23 from rising beyond a certain range. ing.

Further, the second valve body needle valve 23 is connected to the needle valve step portion 23a.
At a position where the small diameter portion of the valve body engages with the inner wall of the valve body, a tapered slope portion 23b is formed from the tip of the small diameter portion of the valve body and projects into the valve seat 26 at a right angle.

With the above configuration, the pressure pb on the outlet B side is introduced into the valve inner chamber 17 through the center guide hole 25 and acts on the outer surface of the bellows 200, and the combined force Pb+Ps with the elasticity Ps of the spring 22 urges the needle valve 23 downward. In addition, the pressure Pa on the inlet A side is
The valve receiver 1 enters from the gap e between the outer surface of the valve body and the inner wall of the valve body.
The pressure inside the bellows becomes Pa through the small hole 19 of No. 8, and the pressure inside the bellows becomes Pa, which urges the bellows upward.

Therefore, if the pressure difference between the inside and outside of the bellows Pa - Pb = △P is set to a predetermined value and the elasticity Ps of the spring 22 is adjusted to be equal to △P, then the balance will be established as Pa - P b = P s, and the second valve needle As shown in FIG. 2, the valve 2-3 stops at a position where the stepped portion 23a engages with the wall of the valve body, and when the pressure difference △P is smaller than Ps (when Pa becomes smaller), the second valve The body 23 is a stepped portion 23
It is stopped by a and does not move upward and maintains its original state. However, when the pressure difference △P becomes smaller than Ps (when Pa becomes smaller), the second valve body needle valve 23 descends and the slope Part 23b
Since a narrow portion of the flow path appears within the flow path, the flow path area is expanded.

When the degree of superheat indicates a valve opening degree of 1 between the flat valve seat 26 and the flat valve 3a, the pressure difference between the population side A (-next side) and the outlet side B (secondary side) is less than a predetermined value. When the needle valve 23 is closed, the second valve body needle valve 23 is at the position shown by the dotted line in Figure 3, but when the pressure difference becomes smaller than a predetermined value, it is at the position shown by the solid line, and the valve opening degree 1 of the first valve body changes. However, the flow path is enlarged to compensate for the decrease in pressure difference and keep the change in flow rate within a small range or to zero, and furthermore, the refrigerant does not generate flash gas or does not generate flash gas when passing through the expansion valve. However, there is no fluctuation in flow rate.

Therefore, in an expansion valve designed for summer characteristics, if the expansion valve according to the present invention is used, the refrigerant flow path at a predetermined degree of superheat will remain constant even if the primary pressure decreases due to the drop in outside temperature in winter. The expansion valve can be used all year round regardless of fluctuations in condensing pressure.

[Brief explanation of the drawing]

Fig. 1 is a broken cross-sectional view of the embodiment of the present invention, Fig. 2 is a partially enlarged cross-sectional view of the main part, Fig. 3 is a partial cross-sectional view explaining the operation of the needle valve, and Fig. 4 is a cross-section of the main part of the conventional example. FIG. 5 is an opening characteristic diagram of the valve of the present invention. 1... Valve body, 2... Communication throttle hole, 3
...First valve body, 4...Diaphragm,
14... Superheat degree adjustment spring, 15... Adjustment screw, 17... Valve interior, 20... Bellows, 21... Rod , 22... Spring, 23... Second valve body needle valve, 24...
... Spring holder, 25 ... Center guide hole, 26 ...
...Flat valve seat.

Claims (1)

[Scope of Claim for Utility Model Registration] In a thermostatic expansion valve having a valve body that opens and closes the throttle valve seat in relation to the degree of superheating of the refrigerant at the outlet side of the evaporator, (a) the throttle valve seat is perpendicular to the valve seat passage; (b) The surface of the first valve body that operates in relation to the degree of superheat, which faces the throttle valve seat surface, is parallel to the valve seat surface, and (c) A needle portion is provided at the tip for adjusting the flow rate. A second valve body having a second valve body is slidably housed in the first valve body, a needled portion at the tip of the second valve body projects into the valve seat, and the valve seat passage is a cylindrical passage. ) Apply condensation pressure to the back surface of the second valve body, apply evaporation pressure to the front surface of the second valve body through the center guide hole of the second valve body, and retreat the second valve body into the first valve body. The second valve body is provided with a spring that biases the second valve body and a step portion that engages with the first valve body that restricts movement of the second valve body toward the valve seat at a predetermined position due to a pressure difference between the condensing pressure and the evaporation pressure. Thermostatic expansion valve