JPH0446347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pressure-balanced expansion valve for a refrigeration cycle, and is suitable for use, for example, in a refrigeration cycle of an automobile air conditioner.

[Prior art]

Conventionally, this type of pressure-balanced expansion valve has been designed so that the high-pressure side pressure acting on the valve body and the high-pressure side pressure acting on the lower surface of the bellows cancel each other out, as shown in Japanese Utility Model Publication No. 10056/1983. This structure has the advantage that it can be made smaller.

However, since the above-mentioned high-pressure side pressure offset structure is adopted, the distance between the valve body and the bellows, which is its driving part, is unavoidably long, and as a result, pressure fluctuations occur when the refrigeration cycle is started, stopped, etc. There is a problem in that the movement of the valve body becomes unstable due to disturbance, which causes vibration and tends to generate abnormal noise.

To explain the above-mentioned problem in more detail, the following two main factors are cited as factors for the above-mentioned pressure fluctuation. The first case is when the pressure on the high pressure side of the cycle fluctuates suddenly, such as when starting or stopping the cycle.

Second, in the pressure-balanced expansion valve described in the above publication, the low pressure chamber is arranged at right angles to the high pressure chamber, so the refrigerant flows at right angles in the valve hole that communicates the two chambers. Since the refrigerant changes direction and flows, the inertial force of the refrigerant causes a contracted flow near the right-angled bend, and this contracted flow causes pressure fluctuations.
The pressure fluctuations caused by the contracted flow make the movement of the valve element unstable, which induces vibration of the valve element.

[Purpose of the invention]

The present invention has been made in view of the above points, and an object of the present invention is to stabilize the movement of a valve body in a pressure-balanced expansion valve.

[Structure of the invention]

In the present invention, in order to achieve the above object, a guide part located inside a valve hole that communicates a high pressure chamber and a low pressure chamber is integrally formed with the valve body, and this guide part is provided with a minute gap on the inner surface of the valve hole. A technical measure is adopted in which the protrusion is formed into a triangular or more polygonal shape having a plurality of protrusions that loosely fit through the protrusion.

As a result, the protrusion of the guide section moves along the inner surface of the valve hole and can reliably guide the valve body, thereby restricting the movement of the valve body in the direction perpendicular to the axis, and causing abnormal noise due to vibration of the valve body. can be effectively prevented.

〔Example〕

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings. FIG. 1 shows the structure of a pressure-balanced expansion valve used in the refrigeration cycle of an automobile air conditioner. Arrows A and B indicate the flow of refrigerant, with arrow A indicating the higher pressure side; It is connected to the outlet of a liquid receiver (not shown). The side indicated by arrow B is the low pressure side and is connected to the refrigerant inlet side of the evaporator (not shown). 1 is a valve body, 2 is a high pressure chamber provided in the valve body 1 and communicates with the high pressure side A, 3 is a low pressure chamber that communicates with the low pressure side B, and the high pressure chamber 2 is connected to the high pressure chamber 2. As shown in the figure, it is formed so as to face in a right angle direction. The high pressure chamber 2 and the low pressure chamber 3 are communicated through a valve hole 4. This valve hole 4
A valve body 5 is pressed against the open end 4a on the low pressure chamber 3 side by a coil spring 6. The setting force of the spring 6 is adjusted by an adjusting screw 7. In other words, the spring 6 is the adjusting screw 7
and the valve body 5. On the other hand, valve body 5
One end of the actuating rod 8 is attached to the holder with a screw. The other end of the actuating rod 8 is soldered to a bellows 9 made of a highly elastic metal such as phosphor bronze. The inside of the bellows 9 communicates with a temperature sensing cylinder 11 attached to an outlet pipe of an evaporator (not shown) through a capillary reach tube 10. The internal pressure of the temperature-sensitive tube 11 changes depending on the refrigerant temperature at the outlet side of the evaporator, and the bellows 9 expands and contracts due to the pressure difference between the internal pressure of the temperature-sensing tube 11 and the transmission force of the actuating rod 8. Ru. An operating space 12 provided outside the bellows 9 communicates with the high pressure chamber 2 through a through hole 13 . Here, since the area of the pressure receiving part 9a of the bellows 9 is equal to the area of the pressure receiving part 5a of the valve body 5, the pressure receiving part 9
The forces that a and the pressure receiving portion 5a receive from the high pressure chamber 2 are equal. Therefore, the valve body 5 is opened and closed by the resultant force (P _S +P _L ) of the pressure P _S of the spring 6 which acts to press the valve body 5 against the open end 4a, the refrigerant pressure P _L in the low pressure chamber 3, and the bellows. 9 and extend the operating rod 8.
A bellows 9 acts to open the valve body 5 via the bellows 9.
, that is, the internal pressure of the temperature-sensitive tube 11 P _T
This is done by the pressure difference between

Both the bellows 9 and the capillary tube 10 are hermetically fixed to a cap 14, and this cap 14 is hermetically fixed to the head of the valve body 1.

On the other hand, the upper part of the above-mentioned valve body 5, that is, the valve hole 4
A guide portion 5b is integrally formed in the inner portion of the guide portion 5b. In this example, this guide portion 5b is
As shown in FIGS. 2 and 3, it is formed in a rectangular shape, and the protrusions 5c at the four corners are formed in an arc shape along the inner peripheral surface of the valve hole 4, and the protrusions 5c and the valve hole A minute gap of about 10 to 20 microns is provided between the valve hole 4 and the inner circumferential surface of the valve hole 4, so that the protruding portion 5b fits loosely into the valve hole 4. The valve body 5 is formed into the illustrated shape by cutting a metal with excellent corrosion resistance, such as brass.

Next, the operation of this embodiment with the above configuration will be explained. First, before the refrigeration cycle compressor (not shown) operates, the refrigerant pressure P _L in the low pressure chamber 3 is
is the pressure inside the temperature sensing cylinder 11, that is, the bellows 9
The internal pressure P is greater than _T. Therefore, if the pressure with which the spring 6 presses the valve body 5 against the open end 4a is P _S , the relational expression P _L +P _S >P _T holds true in this case, so the valve body 5 closes the valve hole 4 .

Next, when the compressor operates, the refrigerant pressure P _L in the low pressure chamber 3 begins to decrease rapidly. Here, since the pressure P _S of the spring 6 is sufficiently small compared to that of a normal expansion valve, the refrigerant pressure P _L of the low pressure chamber 3 is
When the internal pressure is slightly lower than P _T , P _L +P _S <P _T and the valve element 5 opens the valve hole 4 . At this time, the gap between the valve hole 4 and the valve body 5 becomes a throttle passage. Therefore, before the pressure P _L in the low pressure chamber 3 decreases significantly,
The valve hole 4 is opened and refrigerant flows into the evaporator.
Here, in the guide portion 5b, the four protrusions 5c are connected to each other.
The gaps at these locations become refrigerant flow paths. After the compressor starts operating and some time passes, the refrigerant pressure P _L in the low pressure chamber 3 and the internal pressure P _T in the bellows 9 become stable.
The valve body 5 maintains a constant opening degree.

Here, when the cooling load increases, that is, when the temperature of the intake air of the evaporator 5 increases, the refrigerant evaporates quickly, and the temperature of the gas refrigerant at the evaporator outlet increases. Therefore, the temperature and pressure of the temperature sensing tube 11
P _T becomes high and the bellows 9 expands. This displacement of the bellows 9 is transmitted to the operating rod 8, which increases the opening degree of the valve body 5 and increases the amount of refrigerant flowing into the evaporator from the valve hole 4.

On the other hand, when the cooling load decreases, the pressure inside the temperature sensing tube 11 decreases, and the opening degree of the valve body 5 decreases.

By the way, when the valve body 5 is displaced via the actuating rod 8 due to the expansion and contraction of the bellows 9 as described above, the valve body 5
Since the guide portion 5b provided in the valve hole 4 moves along the inner circumferential surface of the valve hole 4, the rigidity of the support system for the valve body 5 is increased, and dry and viscous friction is added between the guide portion 5b and the inlet of the valve hole 4. Therefore, movement of the valve body 5 in the direction perpendicular to the axis is reliably prevented, and generation of abnormal noise due to vibration of the valve body 5 can be prevented.

On the other hand, since the low pressure chamber 3 is arranged perpendicularly to the high pressure chamber 2 as shown in Figure 1, the liquid refrigerant from the high pressure chamber 2 rapidly changes its flow in the perpendicular direction at the valve hole 4. However, in the present invention, the guide portion 5b integrally formed with the valve body 5
is formed into a triangular or more polygonal shape having a plurality of protrusions 5c that loosely fit into the inner surface of the valve hole 4 through minute gaps. The area can be sufficiently narrowed (see FIG. 2), and as a result, the refrigerant flow velocity at the bend is significantly higher than that upstream of the bend, and the upstream of the bend functions as a refrigerant reservoir. As a result, the contracted flow caused by the right-angled bending of the refrigerant is eliminated, so pressure fluctuations due to the contracted flow are reduced, and even more stable valve operation can be obtained.

In addition, in the above-mentioned embodiment, the guide portion 5b of the valve body 5
Although the shape of the valve body 5 is assumed to be square, the shape of the valve body 5 is not limited to this, for example, it may be triangular or the like, or protrusions 5c may be formed at equal intervals on the cylindrical outer peripheral surface. , and can be deformed into various other shapes, in short, any shape can be used as long as it is a triangular or more polygonal shape that has a plurality of protrusions 5c that fit into the inner surface of the valve hole 4 with minute gaps. good.

Further, the guide portion 5b may be formed separately from the valve body 5 using a resin having low frictional resistance and good sliding properties. In this case, the guide portion 5b may be fixed to the actuating rod 8 instead of the valve body 5.

Furthermore, a diaphragm or the like may be used instead of the bellows 8 as the pressure responsive member.

〔Effect of the invention〕

As described above, according to the present invention, since the guide portion 5b is integrally formed with the valve body 5, concentricity between the guide portion 5b and the valve body 5 can be easily obtained, and therefore, the protrusion 5c of the guide portion 5b The gap between the tip of the valve hole 4 and the valve hole 4 is 10~
It can be set to a small value of about 20μ.

Therefore, like an expansion valve for a refrigeration cycle, the difference in high and low pressures before and after the valve is large (more than 10 kg/cm ² ),
Even when the valve body 5 is subjected to a large disturbance due to a rapid change in the refrigerant in the valve throttle passage, the valve body 5 can be effectively guided by the protrusion 5c of the guide portion 5b.

Further, in the present invention, the guide portion 5b integrally formed with the valve body 5 is formed into a polygonal shape of a triangular shape or more having a plurality of protrusions 5c that loosely fit into the inner surface of the valve hole 4 through a minute gap. Therefore, the flow path area of the refrigerant bending portion can be sufficiently narrowed by the guide portion 5b, thereby eliminating the contracted flow caused by the right-angled bending of the refrigerant, so that the pressure fluctuation itself due to the contracted flow is reduced. This has the effect that more stable valve operation can be obtained.

In the present invention, both of the above-mentioned effects work together to reliably prevent the occurrence of abnormal noise due to vibration of the valve body 5.

Furthermore, the above-mentioned vibration prevention of the valve body 5 is achieved by
Since this is achieved by a combination of the guide portion 5b integrally formed with the inner surface of the existing valve hole 4, the structure is very simple and the expansion valve can be made compact.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the expansion valve of the present invention, FIG. 2 is a plan view of the valve body shown in FIG. 1, and FIG. 3 is a longitudinal sectional view of FIG. 2. 2...High pressure chamber, 3...Low pressure chamber, 4...Valve hole, 5
...Valve body, 5b...Guiding part, 5c...Protrusion, 6...
... Spring, 8 ... Operating rod, 9 ... Bellows (pressure responsive member), 11 ... Temperature sensing tube, 12 ... Working space, 13 ... Conduction hole.

Claims (1)

[Scope of Claims] 1. An expansion valve that rapidly expands a high-temperature, high-pressure liquid refrigerant of a refrigeration cycle through a throttle passage to turn it into a low-temperature, low-pressure mist refrigerant; a high-pressure chamber into which the fluid flows, a low-pressure chamber that is formed perpendicularly to the high-pressure chamber and is connected to the refrigerant inlet of the evaporator, and a valve hole that communicates the low-pressure chamber with the high-pressure chamber; a valve body that forms the throttle passage between the valve hole and adjusts the opening degree of the throttle passage; a spring arranged to apply a force to the valve body in a direction to close the valve hole; A temperature-sensitive cylinder that generates a pressure responsive to the refrigerant temperature at the outlet of the evaporator, a pressure-responsive member that receives pressure within the temperature-sensing cylinder, and a pressure-responsive member that communicates with the high-pressure chamber and applies pressure within the temperature-sensitive cylinder to the pressure-responsive member. an actuating space that applies a pressure in the opposite direction to the pressure, an actuating rod that transmits force between the pressure responsive member and the valve body, and a guide that is integrally formed with the valve body and located inside the valve hole. An expansion valve comprising: a guide portion having a polygonal shape of a triangle or larger having a plurality of protrusions that loosely fit into the inner surface of the valve hole through a small gap.