JP7664617B2 - Expansion valve - Google Patents

Description

The present invention relates to an expansion valve.

Conventionally, in the refrigeration cycle used in air conditioning equipment such as car air conditioners, the opening of the expansion valve placed between the condenser and evaporator is controlled to adjust the flow rate of the refrigerant circulating within the refrigeration cycle in order to stabilize the cooling capacity and operate efficiently.

One type of the above expansion valve is disclosed in Patent Document 1. The expansion valve in Patent Document 1 has a connection hole for connecting a high-pressure pipe through which high-temperature, high-pressure refrigerant is supplied from a receiver, a connection hole for connecting a low-pressure pipe that sends the low-temperature, low-pressure refrigerant expanded by the expansion valve to the evaporator, a connection hole for connecting a return pipe from the evaporator outlet, and a connection hole for connecting a pipe for returning the refrigerant that has passed through the expansion valve to the compressor.

JP 2008-51347 A

In the expansion valve of Patent Document 1, the high-pressure side pressure in the high-pressure pipe acts on the valve body in almost the same way in both the valve opening and closing directions. By canceling the high-pressure side pressure, the valve body is not affected by fluctuations in the high-pressure side pressure, and the valve lift can be controlled almost entirely by the driving force of the power element.

According to the expansion valve of Patent Document 1, by canceling the high-pressure side pressure, the valve opening timing can be controlled with precision as long as the internal pressure of the power element is within an appropriate range. However, since the pressure in the valve opening direction decreases after the valve is opened, the balance between the pressure in the valve opening direction and the pressure in the valve closing direction is lost, making it difficult to control the valve body.

The present invention aims to provide an expansion valve that can be made compact and can perform appropriate temperature control regardless of changes in high-pressure side pressure.

In order to achieve the above object, the expansion valve according to the present invention comprises:
a valve body including an inlet side flow passage connected to a high pressure side pipe, an orifice passage connected to the inlet side flow passage, a valve chamber connected to the orifice passage, and an outlet side flow passage connected to the valve chamber and a low pressure side pipe;
a valve body disposed in the valve chamber so as to face the orifice passage;
A power element containing an upper space and a lower space separated by a diaphragm;
a stopper member that is disposed in the lower space and against which the diaphragm abuts;
an actuating rod having one end abutting against the stopper member and the other end abutting against the valve body;
a coil spring that biases the valve body in a direction toward the orifice passage,
the valve body is provided with a communication passage having one end opening into the inlet side flow passage and the other end opening into the lower space,
The lower space is in communication with the valve chamber,
a pressure-receiving portion capable of receiving a pressure from the inlet-side flow passage and displaced integrally with the stopper member is provided in the communication passage,
the pressure-receiving portion includes an O-ring or an annular sheet that forms an outer periphery of the pressure-receiving portion and seals between the pressure-receiving portion and an inner periphery of the communication passage,
The pressure receiving area of the pressure receiving portion is smaller than the cross-sectional area of the orifice passage.
In order to achieve the above object, an expansion valve according to another aspect of the present invention comprises:
a valve body including an inlet side flow passage connected to a high pressure side pipe, an orifice passage connected to the inlet side flow passage, a valve chamber connected to the orifice passage, and an outlet side flow passage connected to the valve chamber and a low pressure side pipe;
a valve body disposed in the valve chamber so as to face the orifice passage;
A power element containing an upper space and a lower space separated by a diaphragm;
a stopper member that is disposed in the lower space and against which the diaphragm abuts;
an actuating rod having one end abutting against the stopper member and the other end abutting against the valve body;
a coil spring that biases the valve body in a direction toward the orifice passage,
the valve body is provided with a communication passage having one end opening into the inlet side flow passage and the other end opening into the lower space,
The lower space is in communication with the valve chamber,
a pressure-receiving portion is provided in the communication passage, the pressure-receiving portion being capable of receiving a pressure from the inlet-side flow passage and displacing integrally with the stopper member;
the pressure-receiving portion is sealed against the inner periphery of the communication passage by an O-ring or an annular sheet provided on the inner periphery of the communication passage,
The pressure receiving area of the pressure receiving portion is smaller than the cross-sectional area of the orifice passage.

The present invention provides an expansion valve that can be miniaturized and performs appropriate temperature control regardless of changes in high-pressure side pressure.

FIG. 1 is a vertical cross-sectional view of an expansion valve according to the present embodiment. FIG. 2 is an enlarged vertical cross-sectional view showing the vicinity of a valve body of an expansion valve according to a comparative example. FIG. 3 is an enlarged vertical cross-sectional view showing the valve body and its surroundings of the expansion valve according to this embodiment. FIG. 4 is a graph in which the vertical axis represents the low pressure side pressure of the expansion valve and the horizontal axis represents the high pressure side pressure. FIG. 5 is an enlarged cross-sectional view showing the vicinity of a stopper member of an expansion valve according to a second embodiment. FIG. 6 is an enlarged cross-sectional view showing the vicinity of a stopper member of an expansion valve according to a third embodiment. FIG. 7 is an enlarged cross-sectional view showing the vicinity of a stopper member of an expansion valve according to a fourth embodiment. FIG. 8 is an enlarged cross-sectional view showing the vicinity of a stopper member of an expansion valve according to a fifth embodiment. FIG. 9 is an enlarged cross-sectional view showing the vicinity of a stopper member of an expansion valve according to the sixth embodiment. FIG. 10 is an enlarged cross-sectional view showing the vicinity of a stopper member of an expansion valve according to the seventh embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

(Direction definition)
In this specification, the direction from the valve disc 3 to the actuating rod 5 is defined as the "upward direction," and the direction from the actuating rod 5 to the valve disc 3 is defined as the "downward direction." Therefore, in this specification, regardless of the attitude of the expansion valve 1, the direction from the valve disc 3 to the actuating rod 5 is called the "upward direction."

First Embodiment
An overview of an expansion valve 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a vertical cross-sectional view of the expansion valve 1 according to this embodiment.

In this embodiment, the expansion valve 1 is fluidly connected to the compressor, the condenser, and the evaporator. The axis of the expansion valve 1 is L.

In FIG. 1, the expansion valve 1 comprises a valve body 2 having a valve chamber VS, a valve element 3, a biasing device 4, an actuating rod 5, and a power element 8.

In addition to the valve chamber VS, the valve body 2 includes a first flow path 21, an intermediate path 23 connecting the first flow path 21 and the valve chamber VS, and a second flow path 22 connected to the valve chamber VS. The first flow path 21 is a supply side flow path, and a refrigerant (also called a fluid) is supplied to the valve chamber VS via the supply side flow path. The second flow path 22 is a discharge side flow path (also called an outlet side flow path). The first flow path 21 is connected to a high-pressure side pipe HT that is connected to a condenser, and the second flow path 22 is connected to a low-pressure side pipe LT that is connected to an evaporator.

The intermediate passage 23 is composed of a horizontal passage 23a extending from the first flow passage 21 in a direction perpendicular to the axis L, and a vertical passage (also called an orifice passage) 23b extending in the direction of the axis L and connected to the valve chamber VS. A communication hole 24 is formed so as to extend upward from the vicinity of the intersection of the horizontal passage 23a and the vertical passage 23b. With reference to FIG. 3 described later, when the inner diameter of the vertical passage 23b is _d1 and the inner diameter of the communication hole 24 (i.e., the outer diameter of the shaft portion 27b of the stopper member 27) is _d2 , _d1 > _d2 . The lower end of the vertical passage 23b constitutes the valve seat 20.

A cylindrical opening 25 is formed at the upper end of the valve body 2, which is coaxial with the axis L, and the lower end of the opening 25 is connected to the communication hole 24. The inner diameter of the opening 25 is larger than the inner diameter of the communication hole 24. The communication hole 24 and the opening 25 form a communication passage.

An O-ring OR1 is placed in the opening 25, and an annular member 87 is attached to the opening 25 by press fitting or the like, thereby holding the O-ring OR1 within the opening 25.

The stopper member 27 has a disk portion 27a and a cylindrical shaft portion 27b connected to the lower side of the disk portion 27a. The shaft portion 27b is inserted through the annular member 87 and the O-ring OR1, and its lower end is inserted into the communication hole 24. The shaft portion 27b is guided relative to the annular member 87 and can slide vertically relative to it. In addition, the outer periphery of the shaft portion 27b contacts the inner periphery of the O-ring OR1, and the outer periphery of the O-ring OR1 contacts the inner periphery of the opening 25, preventing refrigerant leakage from the opening 25 even when the stopper member 27 moves relative to the opening 25 in the direction of the axis L.

The valve body 3 has a cylindrical body 31, a flange portion 32 extending radially outward from the body 31, a conical portion 33 formed at the upper end of the body 31, and a conical protrusion 34 formed protruding downward from the body 31.

The valve disc 3 is disposed within the valve chamber VS. When the valve disc 3 is seated on the valve seat 20, the flow of refrigerant from the intermediate path 23 toward the valve chamber VS is restricted. This state is called a non-communicating state. On the other hand, when the valve disc 3 is separated from the valve seat 20, the flow of refrigerant from the intermediate path 23 toward the valve chamber VS is permitted. This state is called a communicating state.

A pair of actuating rods 5 are disposed symmetrically with respect to the axis L, and are each inserted into an insertion hole 26 in the valve body 2 that extends along the axis L. The lower end of the actuating rod 5 is in contact with the upper surface of the flange portion 32 of the valve body 3. The upper end of the actuating rod 5 is in contact with the lower surface of the disk portion 27a of the stopper member 27.

The actuating rod 5 can press the valve body 3 in the valve opening direction against the biasing force of the biasing device 4. When the actuating rod 5 moves downward, the valve body 3 moves away from the valve seat 20, and the expansion valve 1 opens.

The biasing device 4 has a coil spring 41 made of a wire with a circular cross section wound in a spiral shape, a valve body support 42, and a spring receiving member 43.

The valve body support 42 is formed into a bowl shape with a central recess by press molding a plate material. The tip of the protrusion 34 of the valve body 3 abuts in a point-contact manner against the upper surface of the central recess of the valve body support 42, and the upper end of the coil spring 41 abuts against the periphery of the lower surface of the valve body support 42.

The spring receiving member 43 has a cylindrical shape with a bottom, and the upper surface of its bottom wall supports the lower end of the coil spring 41. The spring receiving member 43 has a male thread 43a that screws into the lower end female thread 2a of the valve body 2, and by screwing the male thread 43a into the lower end female thread 2a, the spring receiving member 43 can be raised and lowered relative to the valve body 2 to adjust the biasing force of the coil spring 41. In addition, an O-ring OR2 is disposed between the outer periphery of the spring receiving member 43 and the inner wall of the valve chamber VS of the valve body 2, thereby sealing the valve chamber VS.

A cover member 28 that shields the spring receiving member 43 is attached to the lower end of the valve body 2. The cover member 28 has a cylindrical shape with a bottom, and a female thread 28a is formed on its inner circumference. The female thread 28a is screwed into the male thread 2b at the lower end of the valve body 2, thereby connecting the valve body 2 and the cover member 28.

The power element 8 has an upper cover member 82, a diaphragm 83, and a receiving member 86.

An opening 82a is formed at the top of the generally conical upper cover member 82, and a tube TB connected to a temperature sensing tube (not shown) is connected to the opening 82a by brazing or the like.

The diaphragm 83 is made of a thin metal (e.g., SUS) plate with multiple concentric circular projections and recesses, and has an outer diameter approximately the same as the outer diameters of the top cover member 82 and the receiving member 86.

The receiving member 86 has a flange portion 86a having an outer diameter approximately the same as the outer diameter of the upper cover member 82, and a cylindrical portion 86b connected to the inner circumference of the flange portion 86a. A male thread portion 86c is formed on the outer circumference of the lower end side of the cylindrical portion 86b.

The upper cover member 82, the diaphragm 83, and the receiving member 86 can be integrated by peripheral welding, for example, by TIG welding, laser welding, plasma welding, etc.

Working gas is sealed in the space SP enclosed by the top cover member 82 and the diaphragm 83, the tube TB, and the temperature sensing tube connected to the tube TB.

The power element 8 can be assembled to the valve body 2 by screwing the male thread portion 86c on the outer periphery of the lower end of the receiving member 86 into the male thread 2c at the upper end of the valve body 2. In the assembled state, the diaphragm 83 faces the upper surface of the stopper member 27, and a lower space LP is formed surrounded by the diaphragm 83, the receiving member 86, and the valve body 2. The lower space LP is connected to the valve chamber VS via a communication hole (not shown), and the lower space LP is thereby maintained at a pressure approximately equal to the low-pressure side pressure.

(Expansion valve operation)
An example of the operation of the expansion valve 1 will be described with reference to Fig. 1. The refrigerant pressurized by the compressor is liquefied by the condenser and sent to the expansion valve 1 via the high-pressure side pipe HT. The refrigerant adiabatically expanded by the expansion valve 1 is sent to the evaporator via the low-pressure side pipe LT, where it is heat exchanged with the air flowing around the evaporator. The temperature sensing bulb (not shown) is disposed near the outlet of the refrigerant returning from the evaporator, and the state (liquid phase/gas phase) of the working gas sealed in the temperature sensing bulb changes depending on the temperature.

In FIG. 1, the space SP in the power element 8 is connected to the inside of the temperature sensing tube via the tube TB. Therefore, when the temperature of the refrigerant returning from the evaporator is relatively low, the liquefaction of the working gas sealed in the temperature sensing tube is promoted. This reduces the pressure in the space SP via the tube TB, and the diaphragm 83 and the stopper member 27 rise, so that the working rod 5 moves upward in response to the biasing force of the coil spring 41, and the valve body 3 seats on the valve seat 20. On the other hand, when the temperature of the refrigerant returning from the evaporator is relatively high, the vaporization of the working gas liquefied in the temperature sensing tube is promoted. This increases the pressure in the space SP via the tube TB, and the diaphragm 83 and the stopper member 27 are pressed downward, so that the working rod 5 moves downward and the valve body 3 moves away from the valve seat 20.

When the valve element 3 is seated on the valve seat 20 (in a non-communicating state), the flow rate of refrigerant sent from the valve chamber VS through the second flow path 22 to the evaporator is restricted, so the temperature of the refrigerant returning from the evaporator rises. On the other hand, when the valve element 3 is separated from the valve seat 20 (in a communicating state), the flow rate of refrigerant sent from the valve chamber VS through the second flow path 22 to the evaporator increases, so the temperature of the refrigerant returning from the evaporator falls. In this way, the expansion valve 1 automatically switches between the open and closed states depending on the refrigerant temperature.

Comparative Example
The effects of this embodiment will be described below in comparison with a comparative example.
Figure 2 is an enlarged longitudinal cross-sectional view showing the valve body and its vicinity of the expansion valve 1' in a comparative example, and Figure 3 is an enlarged longitudinal cross-sectional view showing the valve body and its vicinity of the expansion valve 1 in this embodiment, with hatching omitted in both.

In the expansion valve 1' shown in FIG. 2, a communication passage extending upward from the lateral passage 23a of the intermediate passage 23 and an opening connected thereto are not formed, and instead, a pocket hole 25' into which the shaft portion 27b of the stopper member 27 is slidably fitted is provided on the upper surface of the valve body 2'. The other configurations are the same as those of this embodiment, so the same reference numerals are used and repeated explanations are omitted.

In the expansion valve 1' shown in Fig. 2, the balance of the vertical forces acting on the valve body 3 will be considered. Here, the internal pressure of the space SP of the power element 8 is P _E , the effective area of the diaphragm 83 is A, the spring force of the coil spring 41 is F, the orifice diameter of the vertical passage 23b of the intermediate passage 23 is d ₁ , the refrigerant pressure on the high pressure side (referred to as the high pressure side pressure) in the vertical passage 23b (i.e., the first passage 21) is P _H , and the refrigerant pressure on the low pressure side (referred to as the low pressure side pressure) in the valve chamber VS (i.e., the second passage 22) is P _L. Note that although the valve body 3, the operating rod 5, and the stopper member 27 are each separate parts, they are sandwiched vertically between the diaphragm 83 and the coil spring 41, and therefore are considered here as an integrated part.

First, the force applied to the valve body 3 is a force transmitted from the diaphragm 83 via the operating rod 5. The diaphragm 83 deforms according to the internal pressure balance between the upper space SP and the lower space LP. That is, the force pushing the diaphragm 83 downward can be expressed as P _E A, while the force pushing the diaphragm 83 upward can be expressed as P _L A.

Next, the valve disc 3 receives refrigerant pressure from both the valve chamber VS and the vertical passage 23b across the valve seat 20. That is, the valve disc 3 receives a downward force corresponding to the difference between the high-pressure side pressure and the low-pressure side pressure, ΔP=(P _H -P _L ). This force is called the high-pressure influence force and is expressed as ΔP·(πd ₁ ² /4).

Furthermore, the valve body 3 receives an upward spring force F from the coil spring 41.

Assuming that these forces acting on the valve disc 3 are balanced, the following formula (1) is established. In formula (1), the left side represents the resultant force in the downward direction (valve opening side), and the right side represents the resultant force in the upward direction (valve closing side).
P _E・A+ΔP・(πd ₁ ² /4)=P _L・A+F (1)

However, there is a demand to increase the capacity without making the expansion valve larger. One idea for increasing the capacity is to increase the cross-sectional area of the orifice passage. However, if the cross-sectional area of the orifice passage is simply increased, the valve opening amount of the valve body 3 increases more than necessary when the high-pressure side pressure increases, and when the refrigerant flows from the orifice passage to the valve chamber, it flows into the low-pressure side pipe without being sufficiently evaporated (i.e., without becoming low pressure), resulting in a decrease in the so-called superheat degree (the temperature rise of the refrigerant from the saturation temperature). If the superheat degree decreases, there is a risk of malfunction (liquid return, high pressure effect) occurring due to liquid refrigerant flowing into the compressor. Such high-pressure effect can be eliminated by making the power element larger, but in recent years, there has been a strong demand for smaller expansion valves, and the effective area A of the diaphragm becomes smaller accordingly, so measures to suppress the decrease in superheat degree are necessary even when a small-diameter diaphragm is used.

Figure 4 is a graph showing the low-pressure side pressure of the expansion valve on the vertical axis and the high-pressure side pressure on the horizontal axis. In Figure 4, the low-pressure side pressure initially increases linearly with respect to the high-pressure side pressure, but then the rate of increase decreases. In refrigeration cycles that use expansion valves, they are generally used in a range where the high-pressure side pressure is equal to or greater than a reference value Pr.

Ideally, it is desirable that the low-pressure side pressure is approximately constant even if the high-pressure side pressure increases. However, according to the results of the study by the present inventors, in the expansion valve of the comparative example, as shown by the dashed line S in Fig. 4, as the high-pressure side pressure increases from the reference value Pr, the low-pressure side pressure also increases, and the degree of superheat tends to decrease. In order to satisfy the formula (1), the pressure difference ΔP must be constant, and therefore, when the high-pressure side pressure P _H increases, the low-pressure side pressure P _L also increases.

The following describes the balance of the vertical forces acting on the valve body 3 in the expansion valve 1 of this embodiment shown in Figure 3. By providing the communication hole 24, the stopper member 27 receives the high-pressure side pressure upward through the shaft portion 27b, and receives the low-pressure side pressure downward from the lower space LP. Therefore, the stopper member 27 is pushed upward according to the pressure difference ΔP.

Here, assuming that the outer diameter of the shaft portion 27b is _d2 and the other values are the same as in the comparative example, the following formula (2) is established by assuming that the vertical forces acting on the valve body 3 are balanced. In formula (2), the left side represents the resultant force of the downward (valve-opening) forces, and the right side represents the resultant force of the upward (valve-closing) forces.
P _E・A+ΔP・(πd ₁ ² /4)= _PL・A+F+ΔP・(πd ₂ ² /4) (2)

Furthermore, equation (2) is transformed to obtain equation (3).
P _E・A+ΔP・(π(d ₁ ² − _{d 2} ² )/4)=P _L・A+F (3)

Comparing formula (3) with formula (1), it can be seen that the high pressure influence in this embodiment decreases in proportion to (d ₁ ² -d ₂ ² ) by providing the communication hole 24. Therefore, as shown by solid line B in Fig. 4, the low pressure side pressure relative to the high pressure side pressure becomes approximately constant in the region equal to or higher than the reference value Pr. As a result, even if the effective area A of the diaphragm 83 becomes small, the decrease in the degree of superheat is suppressed, and the high pressure influence can be suppressed.

Furthermore, according to this embodiment, by setting the outer diameter _d2 of the shaft portion 27b to an appropriate value, even if the pressure difference ΔP decreases after the valve is opened, the resultant force on the valve opening side and the resultant force on the valve closing side can be adjusted to approach each other, whereby an appropriate force is applied from the power element 8 to the valve body 3, making it easy to control the amount of opening of the valve body 3 after the valve is opened.
However, according to the results of the inventors' studies, it has been found that if _d1 = _d2 , the low-pressure side pressure relative to the high-pressure side pressure gradually decreases in the region equal to or greater than the reference value Pr, as shown by the dotted line C in Fig. 4, resulting in characteristics that are not favorable for controlling the expansion valve. For this reason, it is preferable to make _d1 > _d2 (i.e., make the cross-sectional area of the vertical passage 23b larger than the cross-sectional area (pressure-receiving area) of the outer diameter of the shaft portion 27b).

Second Embodiment
5 is an enlarged cross-sectional view of the stopper member 27A and its surroundings of the expansion valve according to the second embodiment. This embodiment differs from the above-described embodiment in the stopper member 27A and the configuration disposed within the opening 25. The other configurations are the same as those of the above-described embodiment, so the same reference numerals are used and repeated explanations are omitted.

In FIG. 5, the stopper member 27A has a disk portion 27Aa, a medium diameter shaft portion 27Ab coaxially connected to the disk portion 27Aa, a large diameter shaft portion 27Ac having a larger diameter than the medium diameter shaft portion 27Ab, and a small diameter shaft portion 27Ad having a smaller diameter than the large diameter shaft portion 27Ac. The medium diameter shaft portion 27Ab, the large diameter shaft portion 27Ac, and the small diameter shaft portion 27Ad are inserted into the opening 25, and the outer diameter of the large diameter shaft portion 27Ac is approximately equal to the inner diameter of the opening 25. In this embodiment, the large diameter shaft portion 27Ac is guided relative to the opening 25 and can slide vertically relative to it.

The step 27Ae at the boundary between the large diameter shaft portion 27Ac and the small diameter shaft portion 27Ad is a tapered surface that expands in diameter downward. A ring-shaped sheet 85 made of a resin such as PTFE is attached so that the small diameter shaft portion 27Ad is inserted through it. A male thread is formed around the periphery of the small diameter shaft portion 27Ad, and a nut (fixing member) 87A can be screwed onto this male thread. By screwing the nut 87A onto the male thread of the small diameter shaft portion 27Ad and tightening it, the nut 87A screws upward, and the ring-shaped sheet 85 can be clamped and fixed between the conical upper surface of the nut 87A and the step 27Ae. When the ring-shaped sheet 85 is fixed, it becomes tapered following the shape of the step 27Ae.

In this embodiment, no O-ring is provided, but instead the outer periphery of the annular sheet 85 abuts against the entire inner periphery of the opening 25, suppressing refrigerant leakage when the stopper member 27A slides relative to the opening 25 as it is displaced. In this embodiment, the outer diameter of the annular sheet 85 (the inner diameter of the opening 25) is the pressure-receiving diameter (d ₂ ). Here, the "pressure-receiving diameter" refers to the outer diameter of a part that receives the pressure of the refrigerant by blocking the inside of the communication passage, and the "pressure-receiving area" is obtained by converting the pressure-receiving diameter into an area.

Third Embodiment
6 is an enlarged cross-sectional view of the stopper member 27B and its vicinity of the expansion valve according to the third embodiment. In this embodiment, the shape of the stopper member 27B is different from that of the first embodiment. Other configurations are the same as those of the above-mentioned embodiments, so the same reference numerals are used and repeated explanations are omitted.

In FIG. 6, the stopper member 27B has a disk portion 27Ba, a large diameter shaft portion 27Bb coaxially connected to the disk portion 27Ba, and a small diameter shaft portion 27Bc having a smaller diameter than the large diameter shaft portion 27Bb. A portion of the large diameter shaft portion 27Bb and the small diameter shaft portion 27Bc are inserted into the opening 25, and the outer diameter of the large diameter shaft portion 27Bb is approximately equal to the inner diameter of the opening 25. In this embodiment, the large diameter shaft portion 27Bb is guided relative to the opening 25 and can slide vertically relative to the opening 25.

The lower end of the small diameter shaft portion 27Bc is inserted into the communication hole 24. An O-ring OR1 is disposed between the outer periphery of the small diameter shaft portion 27Bc and the inner periphery of the opening 25. When the O-ring OR1 receives high-pressure side pressure from below, it moves upward from the state shown in FIG. 6 and is pressed against the lower surface of the large diameter shaft portion 27Bb. As the stopper member 27B is displaced, the O-ring OR1 slides relative to the inner periphery of the opening 25, thereby preventing refrigerant leakage. In this embodiment, since the gap between the communication hole 24 and the small diameter shaft portion 27Bc is relatively large, the outer diameter of the O-ring OR1 (the inner diameter of the opening 25) becomes the pressure-receiving diameter (d ₂ ).

Fourth Embodiment
7 is an enlarged cross-sectional view of the stopper member 27C and its surroundings of the expansion valve according to the fourth embodiment. In this embodiment, the stopper member 27C and the configuration disposed within the opening 25 are different from those of the first embodiment. The other configurations are the same as those of the above-mentioned embodiments, so the same reference numerals are used and the repeated description will be omitted.

In FIG. 7, the stopper member 27C has a disk portion 27Ca and a hollow shaft portion 27Cb that is coaxially connected to the disk portion 27Ca. In this embodiment, the hollow shaft portion 27Cb is guided relative to the opening 25 and can slide vertically. The lower end surface of the hollow shaft portion 27Cb is a tapered surface that increases in diameter as it approaches downward. An annular sheet 85C made of a resin such as PTFE is attached so as to abut against the lower end surface of the hollow shaft portion 27Cb.

The fixing pin (fixing member) 87C is formed by connecting a head 87Ca and a shaft 87Cb having a smaller diameter than the head 87Ca. When the shaft 87Cb is press-fitted into the hollow shaft 27Cb, the annular sheet 85C is sandwiched and fixed between the lower end surface of the hollow shaft 27Cb and the head 87Ca. At this time, the annular sheet 85C conforms to the lower end surface of the hollow shaft 27Cb, and the outer periphery of the annular sheet 85C elastically deforms to encase the head 87Ca, and contacts the inner periphery of the opening 25 over the entire circumference.

In this embodiment, no O-ring is provided, but instead the outer periphery of the annular sheet 85C abuts against the entire inner periphery of the opening 25, suppressing refrigerant leakage when the stopper member 27C slides relative to the opening 25 as it is displaced. In this embodiment, the outer diameter of the annular sheet 85C (the inner diameter of the opening 25) is the pressure-receiving diameter (d ₂ ).

Fifth Embodiment
8 is an enlarged cross-sectional view of the stopper member 27D and its vicinity of the expansion valve according to the fifth embodiment. In this embodiment, the shape of the stopper member 27D is different from that of the first embodiment. Other configurations are the same as those of the above-mentioned embodiments, so the same reference numerals are used and repeated explanations are omitted.

In FIG. 8, the stopper member 27D has a disk portion 27Da and a cylindrical shaft portion 27Db that is coaxially connected to the disk portion 27Da. The outer diameter of the shaft portion 27Db is approximately equal to the inner diameter of the opening 25, and a circumferential groove 27Dc is formed on the outer periphery of the shaft portion 27Db, and an O-ring OR3 is held in the circumferential groove 27Dc. In this embodiment, the shaft portion 27Db is guided relative to the opening 25 and can slide vertically relative to it.

As the stopper member 27D is displaced, the O-ring OR3 held by the shaft portion 27Db slides relative to the opening 25, thereby preventing refrigerant leakage. In this embodiment, the outer diameter of the O-ring OR3 (the inner diameter of the opening 25) becomes the pressure-receiving diameter (d ₂ ). Furthermore, in this embodiment, it is possible to reduce the number of parts.

Sixth Embodiment
9 is an enlarged cross-sectional view of the stopper member 27E and its surroundings of the expansion valve according to the sixth embodiment. The sixth embodiment differs from the first embodiment in the stopper member 27E and the configuration disposed within the opening 25. The other configurations are the same as those of the above-mentioned embodiments, so the same reference numerals are used and repeated explanations are omitted.

In FIG. 9, the stopper member 27E has a disk portion 27Ea and a cylindrical shaft portion 27Eb that is coaxially connected to the disk portion 27Ea. The seal retaining member 87E is composed of a cylindrical base portion 87Ea and a shaft portion 27Eb that are connected to each other. A circumferential groove 87Ec is formed on the outer periphery of the base portion 87Ea, and an O-ring OR3 is held in the circumferential groove 27Ec. The outer diameters of the base portion 87Ea and the hollow cylindrical portion 87Eb are approximately equal to the inner diameter of the opening 25. In this embodiment, the seal retaining member 87E is guided relative to the opening 25 and can slide vertically relative to it.

The seal retaining member 87E can be attached to the stopper member 27E by fitting the hollow cylindrical portion 87Eb to the shaft portion 27Eb by press fitting, or by connecting by press fitting, gluing, brazing, welding, etc.

As the stopper member 27E is displaced, the O-ring OR3 held by the seal holding member 87E slides relative to the opening 25, thereby preventing refrigerant leakage. In this embodiment, the outer diameter of the O-ring OR3 (the inner diameter of the opening 25) is the pressure-receiving diameter (d ₂ ). In this embodiment, the seal holding member 87E is a separate part from the stopper member 27E, which makes machining easier.

Seventh Embodiment
10 is an enlarged cross-sectional view of the stopper member 27F and its surroundings of the expansion valve according to the seventh embodiment. In this embodiment, the stopper member 27F and the configuration disposed within the opening 25 are different from those of the first embodiment. The other configurations are the same as those of the above-mentioned embodiments, so the same reference numerals are used and repeated explanations are omitted.

In FIG. 10, the stopper member 27F has a disk portion 27Fa and a cylindrical shaft portion 27Fb that is coaxially connected to the disk portion 27Fa. A ring-shaped sheet 85F made of a resin such as PTFE is disposed within the opening 25, and is pressed against the bottom surface of the opening 25 and held therein by a ring-shaped member 87F that is press-fitted into the opening 25.

The shaft portion 27Fb penetrates the annular member 87F and the annular sheet 85F and is inserted into the communication hole 24. In this embodiment, the shaft portion 27Fb is guided by the annular member 87F and can slide relatively in the up and down direction. In addition, the outer periphery of the shaft portion 27Fb abuts against the inner periphery of the annular sheet 85F, and the outer periphery of the annular sheet 85F abuts against the inner periphery of the opening 25.

In this embodiment, an O-ring is not provided, but instead, an annular sheet 85F abuts against the opening 25 and the shaft portion 27Fb over the entire circumference, suppressing refrigerant leakage when the stopper member 27F displaces and slides relative to each other. In this embodiment, the outer diameter of the shaft portion 27Fb is the pressure-receiving diameter (d ₂ ).

The present invention is not limited to the above-described embodiment. Any of the components of the above-described embodiment may be modified within the scope of the present invention. Any of the components of the above-described embodiment may be added or omitted.

1: Expansion valve 2: Valve body 3: Valve element 4: Biasing device 5: Actuating rod 6: Ring spring 8: Power element 20: Valve seat 21: First flow path 22: Second flow path 23: Intermediate path 24: Communication hole 25: Openings 27-27F: Stopper member 41: Coil spring 42: Valve element support 43: Spring receiving member VS: Valve chamber HT: High pressure side piping LT: Low pressure side piping

Claims (12)

a valve body including an inlet side flow passage connected to a high pressure side pipe, an orifice passage connected to the inlet side flow passage, a valve chamber connected to the orifice passage, and an outlet side flow passage connected to the valve chamber and a low pressure side pipe;
a valve body disposed in the valve chamber so as to face the orifice passage;
A power element containing an upper space and a lower space separated by a diaphragm;
a stopper member that is disposed in the lower space and against which the diaphragm abuts;
an actuating rod having one end abutting against the stopper member and the other end abutting against the valve body;
a coil spring that biases the valve body in a direction toward the orifice passage,
the valve body is provided with a communication passage having one end opening into the inlet side flow passage and the other end opening into the lower space,
The lower space is in communication with the valve chamber,
a pressure-receiving portion is provided in the communication passage, the pressure-receiving portion being capable of receiving a pressure from the inlet-side flow passage and displacing integrally with the stopper member;
the pressure-receiving portion includes an O-ring or an annular sheet that forms an outer periphery of the pressure-receiving portion and seals between the pressure-receiving portion and an inner periphery of the communication passage,
The pressure receiving area of the pressure receiving portion is smaller than the cross-sectional area of the orifice passage.
An expansion valve characterized by: a valve body including an inlet side flow passage connected to a high pressure side pipe, an orifice passage connected to the inlet side flow passage, a valve chamber connected to the orifice passage, and an outlet side flow passage connected to the valve chamber and a low pressure side pipe;
a valve body disposed in the valve chamber so as to face the orifice passage;
A power element containing an upper space and a lower space separated by a diaphragm;
a stopper member that is disposed in the lower space and against which the diaphragm abuts;
an actuating rod having one end abutting against the stopper member and the other end abutting against the valve body;
a coil spring that biases the valve body in a direction toward the orifice passage,
the valve body is provided with a communication passage having one end opening into the inlet side flow passage and the other end opening into the lower space,
The lower space is in communication with the valve chamber,
a pressure-receiving portion is provided in the communication passage, the pressure-receiving portion being capable of receiving a pressure from the inlet-side flow passage and displacing integrally with the stopper member;
the pressure-receiving portion is sealed against the inner periphery of the communication passage by an O-ring or an annular sheet provided on the inner periphery of the communication passage,
The pressure receiving area of the pressure receiving portion is smaller than the cross-sectional area of the orifice passage.
An expansion valve characterized by: The upper space of the power element is connected to the temperature sensing tube via a tube.
3. The expansion valve according to claim 1 or 2. the stopper member includes a disk portion facing the diaphragm and a shaft portion disposed in the communication passage, the disk portion being connected to the shaft portion,
The O-ring is disposed between the shaft portion and an inner periphery of the communication passage,
The pressure-receiving portion is the shaft portion and the O-ring.
2. The expansion valve according to claim 1 . the stopper member includes a disk portion facing the diaphragm and a shaft portion disposed in the communication passage and serving as the pressure receiving portion,
An annular member is attached in the communication passage to hold the O-ring and guide the shaft portion.
3. The expansion valve according to claim 2. the shaft portion has a circumferential groove for holding the O-ring;
The pressure-receiving portion includes the O-ring and the shaft portion.
5. The expansion valve according to claim 4. the stopper member includes a disk portion facing the diaphragm and a shaft portion disposed in the communication passage, the disk portion being connected to the shaft portion,
the shaft portion is connected to a seal retaining member that retains the O-ring, and the seal retaining member is guided by the communication passage;
The pressure-receiving portion includes the O-ring and the seal retaining member.
2. The expansion valve according to claim 1 . the stopper member includes a disk portion facing the diaphragm and a shaft portion disposed in the communication passage, the disk portion being connected to the shaft portion,
the annular seat is attached to the shaft portion so as to be in contact with an inner periphery of the communication passage and is displaced integrally with the shaft portion;
The pressure-receiving portion includes the annular sheet and the shaft portion.
2. The expansion valve according to claim 1 . A fixing member for fixing the annular sheet to the shaft portion is provided.
9. The expansion valve according to claim 8. the stopper member includes a disk portion opposed to the diaphragm and a shaft portion disposed in the communication passage and serving as the pressure receiving portion,
The annular sheet is attached to the communication passage via an annular member and seals between an inner periphery of the communication passage and the shaft portion.
3. The expansion valve according to claim 2. The shaft portion is guided by the annular member.
11. The expansion valve according to claim 10. the communication passage has an opening communicating with the lower space and a communication hole communicating with the inlet side flow passage,
The cross-sectional area of the opening is larger than the cross-sectional area of the communication hole,
A cross-sectional area of the orifice passage is larger than a cross-sectional area of the communication hole,
The pressure receiving portion is disposed in the opening.
The expansion valve according to any one of claims 1 to 11.

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