JP7624712B2 - Expansion valve - Google Patents

Description

The present invention relates to an expansion valve.

Conventionally, refrigeration cycles used in air conditioners installed in automobiles use a temperature-sensing expansion valve that adjusts the amount of refrigerant passing through depending on the temperature.

For a typical expansion valve, a high-pressure pipe through which refrigerant is sent from the condenser of the refrigeration cycle and a low-pressure pipe through which refrigerant is sent from the evaporator are each connected separately. In contrast, the expansion valve disclosed in Patent Document 1 discloses a system in which a double pipe, with the low-pressure pipe as the inner pipe and the high-pressure pipe as the outer pipe, is connected to the expansion valve. This system simplifies the management of the pipes.

JP 2020-94793 A

Incidentally, the expansion valve is provided with a power element equipped with a temperature-sensing part in which an inert gas or the like is sealed. The power element opens and closes the valve body via the operating rod by utilizing the change in gas volume caused by heat transferred between the inside and outside of the temperature-sensing part. However, if the time constant of the temperature-sensing part is small, there is a risk that the valve body will vibrate and repeatedly open and close, a phenomenon known as hunting, will occur. However, Patent Document 1 does not disclose a specific structure for suppressing the hunting phenomenon.

The present invention aims to provide an expansion valve that can be connected to a double pipe and suppresses vibration of the valve body unit.

In order to achieve the above object, the expansion valve according to the present invention comprises:
An expansion valve capable of connecting a double pipe in which a low-pressure refrigerant passes through an inner pipe and a high-pressure refrigerant passes through an intermediate flow passage that is a space between an outer pipe arranged around the inner pipe and the inner pipe,
a valve body including a valve chamber having a valve seat, a valve through hole as a throttle connecting the valve chamber with a downstream side of the valve chamber , and a high-pressure flow passage connected from the intermediate flow passage to the valve chamber and through which a high-pressure refrigerant flows;
a valve body unit including a valve body that can be seated on the valve seat , a valve body support including a main body that supports the valve body and a flange portion formed on the main body ;
an actuating rod disposed in the valve through hole and in contact with the valve body;
A power element that drives the actuation rod;
a coil spring disposed on the opposite side of the actuation rod from the power element and biasing the valve body unit toward the power element via the flange portion of the valve body support ;
the high-pressure flow passage is formed at an angle with respect to an axis of the valve body unit so that the high-pressure refrigerant that has flowed through the high-pressure flow passage from the intermediate flow passage toward the valve chamber hits the flange portion of the valve body support ,
When the high pressure flow passage is projected along an axis of the high pressure flow passage, the projected image overlaps with the flange portion of the valve body support in a valve closed state.

The present invention provides an expansion valve that can connect double piping and suppress vibration of the valve body unit.

FIG. 1 is a schematic cross-sectional view showing an example in which an expansion valve according to the present embodiment is applied to a refrigerant circulation system. FIG. 2 is an enlarged vertical cross-sectional view showing the periphery of the valve body of this embodiment. FIG. 3 is a vertical cross-sectional view similar to FIG. 2, showing a modification of this embodiment. FIG. 4 is a perspective view showing a cover member according to this modified example. FIG. 5 is a vertical cross-sectional view of an expansion valve according to the second 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 the present embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic cross-sectional view showing an example in which the expansion valve 1 according to the present embodiment is applied to a refrigerant circulation system 100. Figure 2 is a vertical cross-sectional view showing an enlarged view of the periphery of a valve body according to the present embodiment.

In this embodiment, the expansion valve 1 is fluidly connected to the compressor 101, the condenser 102, and the evaporator 104. 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.

The valve body 2 includes a first flow path (also called a high-pressure flow path) 21, a second flow path 22, an intermediate chamber 221, and a return flow path 23 in addition 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), and the fluid in the valve chamber VS is discharged to the outside of the expansion valve via the valve hole 27, the intermediate chamber 221, and the discharge side flow path. A pipe (not shown) that is connected to the inlet side of the evaporator 104 is connected to the second flow path 22.

The return flow passage 23 extends through the valve body 2 perpendicular to the axis L. The axis of the return flow passage 23 is O. The return flow passage 23 is composed of an inlet passage 23a to which a pipe (not shown) connected to the outlet side of the evaporator 104 is connected, an intermediate passage (also called a low-pressure passage) 23b, a first enlarged diameter hole 23c larger in diameter than the intermediate passage 23b, a second enlarged diameter hole 23d larger in diameter than the first enlarged diameter hole 23c, and a third enlarged diameter hole 23e larger in diameter than the second enlarged diameter hole 23d, which are coaxially connected. The intermediate passage 23b is connected to the lower space LS of the power element 8 via the vertical hole 2a, as will be described in detail later.

A double pipe 50 is connected to the return flow path 23. The double pipe 50 has an inner pipe 51, the end of which fits into the intermediate path 23b, and an outer pipe 52, which contains the inner pipe 51 and the end of which fits into the second enlarged diameter hole 23d. The inner pipe 51 has a flange portion 51a near the end of the inner pipe 51, which is formed by expanding a part of the pipe and crushing it in the axial direction. An O-ring OR1 held by the flange portion 51a is placed between the end of the inner pipe 51 and the flange portion 51a, which seals the gap between the first enlarged diameter hole 23c and the outer periphery of the inner pipe 51, preventing refrigerant leakage.

The outer pipe 52 also has a flange portion 52a near its end, which is formed by expanding a portion of the pipe and crushing it in the axial direction. The end of the outer pipe 52 does not bottom out on the step of the second enlarged diameter hole 23d, and the flange portion 52a abuts against the side of the valve body 2. An O-ring OR2 held by the flange portion 52a is placed between the end of the outer pipe 52 and the flange portion 52a, thereby sealing the gap between the third enlarged diameter hole 23e and the outer periphery of the outer pipe 52 and preventing refrigerant leakage.

The inner pipe 51 is connected to the inlet of the compressor 101, and the annular space between the outer pipe 52 and the inner pipe 51 (called the intermediate flow path) is connected to the outlet of the condenser 102.

The first flow passage 21 has an axis (center axis) X1 (FIG. 2) in a plane including the axis L and the axis O, and is inclined with respect to the axis L and the axis O, and its upper end opens to the inner circumference of the second enlarged diameter hole 23d. On the other hand, the first flow passage 21 has a small diameter passage 21a, which is smaller in diameter than the first flow passage 21, at its lower end and is coaxial with the first flow passage 21. This small diameter passage 21a is connected to the inner circumference of the valve chamber VS below the valve seat 20. In other words, the inside of the second enlarged diameter hole 23d and the valve chamber VS are connected via the first flow passage 21. Referring to FIG. 2, when the small diameter passage 21a is projected onto the valve chamber VS along the axis X1 of the first flow passage 21, the projected image overlaps with the valve body 3 and the valve body support 42.

The valve chamber VS and the intermediate chamber 221 are in communication with each other via the valve seat 20 and the valve through hole 27. The actuating rod insertion hole 28 formed above the intermediate chamber 221 has the function of guiding the actuating rod 5, and the annular recess 29 formed above the actuating rod insertion hole 28 has the function of accommodating the ring spring 6. The ring spring 6 applies a predetermined biasing force by abutting multiple spring pieces against the outer periphery of the actuating rod 5.

The valve disc 3 is disposed within the valve chamber VS. When the valve disc 3 is seated on the valve seat 20 of the valve body 2, the flow of refrigerant through the valve hole 27 is restricted. This state is called the non-communicating state. However, even when the valve disc 3 is seated on the valve seat 20, a restricted amount of refrigerant may flow. On the other hand, when the valve disc 3 is separated from the valve seat 20, the flow of refrigerant passing through the valve hole 27 increases. This state is called the communicating state.

The actuating rod 5 is inserted through the valve through hole 27 with a specified gap. The lower end of the actuating rod 5 is in contact with the upper surface of the valve body 3. The upper end of the actuating rod 5 is fitted into the fitting hole at the lower end of the stopper member 84.

The actuating rod 5 can press the valve body 3 in the valve opening direction along the axis L 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 attached to the upper end of the coil spring 41, and the spherical valve body 3 is welded to its upper surface, forming a single unit. The valve body 3 and the valve body support 42 form a valve body unit. However, the valve body unit may also be formed by the valve body 3 alone. In that case, when the small diameter passage 21a is projected onto the valve chamber VS along the axis X1 of the first flow path 21, the projected image will overlap only the valve body 3. The axis of the valve body unit refers to a straight line that includes the trajectory along which the center of gravity of the valve body unit moves in response to the valve opening operation, and here coincides with the axis L of the expansion valve 1.

The spring bearing member 43 that supports the lower end of the coil spring 41 can be screwed into the valve body 2 and has the functions of sealing the valve chamber VS and adjusting the biasing force of the coil spring 41.

The power element 8 has a plug 81, an upper cover member 82, a diaphragm 83, a receiving member 86, and a stopper member 84.

The opening at the top of the roughly conical top cover member 82 can be sealed with a plug 81.

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 is formed, for example, by press-molding a metal plate, and consists of a flange portion and a hollow cylindrical portion connected together.

The stopper member 84 is disposed between the upper cover member 82 and the receiving member 86, and its upper surface contacts the center of the lower surface of the diaphragm 83.

In assembling the power element 8, the stopper member 84 is placed between the diaphragm 83 and the receiving member 86, and the outer peripheries of the upper cover member 82, the diaphragm 83, and the receiving member 86 are overlapped and the outer peripheries are circumferentially welded together by, for example, TIG welding, laser welding, plasma welding, etc.

Next, the working gas is injected into the space surrounded by the upper cover member 82 and the diaphragm 83 (called the pressure actuated chamber PO) through an opening formed in the upper cover member 82, and the opening is then sealed with a plug 81, which is then fixed to the upper cover member 82 using projection welding or the like.

When the power element 8 assembled as described above is attached to the valve body 2, the male thread 86a on the outer periphery of the lower end of the hollow cylindrical portion of the receiving member 86 is screwed into the female thread 2b formed on the inner periphery of the vertical hole 2a that communicates with the return flow path 23 of the valve body 2. When the male thread 86a of the receiving member 86 is screwed into the female thread 2b, the lower surface of the flange portion of the receiving member 86 abuts against the upper end surface of the valve body 2. This allows the power element 8 to be fixed to the valve body 2.

At this time, a packing PK is interposed between the power element 8 and the valve body 2 to prevent refrigerant leakage when the power element 8 is attached to the valve body 2. In this state, the lower space LS of the power element 8 communicates with the return flow path 23 via the vertical hole 2a.

(Expansion valve operation)
An example of the operation of the expansion valve 1 will be described with reference to Fig. 1. A high-pressure refrigerant pressurized by a compressor 101 is liquefied by a condenser 102 and sent to the expansion valve 1. The refrigerant adiabatically expanded by the expansion valve 1 is sent to an evaporator 104, where it is heat exchanged with air flowing around the evaporator. The refrigerant returning from the evaporator 104 enters the return flow path 23 of the expansion valve 1, and is returned to the compressor 101 side through the inner pipe 51 of the double pipe 50. At this time, the fluid pressure of the return flow path 23 becomes lower than the fluid pressure in the second flow path 22 by passing through the evaporator 104. The refrigerant that has passed through the evaporator 104 is called a low-pressure refrigerant.

Low-pressure refrigerant is sent from the expansion valve 1 to the compressor 101, and high-pressure refrigerant is sent from the condenser 102 to the expansion valve 1. More specifically, the high-pressure refrigerant from the condenser 102 is supplied to the valve chamber VS via the intermediate flow path between the outer pipe 52 and the inner pipe 51 of the double pipe 50, and the first flow path 21.

When the valve body 3 is seated on the valve seat 20 (in a non-communicating state), the flow rate of the refrigerant sent from the valve chamber VS through the valve hole 27, the intermediate chamber 221, and the second flow path 22 to the evaporator 104 is restricted. On the other hand, when the valve body 3 is separated from the valve seat 20 (in a communicating state), the flow rate of the refrigerant sent from the valve chamber VS through the valve hole 27, the intermediate chamber 221, and the second flow path 22 to the evaporator 104 increases. The expansion valve 1 is switched between the closed state and the open state by the operating rod 5 connected to the power element 8 via the stopper member 84.

In FIG. 1, the power element 8 is provided with a pressure actuated chamber PO and a lower space LS separated by a diaphragm 83. Therefore, when the working gas in the pressure actuated chamber PO is liquefied, the diaphragm 83 and the stopper member 84 rise, and the working rod 5 moves upward in response to the biasing force of the coil spring 41. On the other hand, when the liquefied working gas is vaporized, the diaphragm 83 and the stopper member 84 are pressed downward, and the working rod 5 moves downward. In this way, the expansion valve 1 is switched between the open and closed states.

Furthermore, the lower space LS of the power element 8 is connected to the return flow path 23 via the vertical hole 2a. Therefore, the volume of the working gas in the pressure actuated chamber PO changes depending on the temperature and pressure of the refrigerant flowing through the return flow path 23, and the actuating rod 5 is driven. In other words, in the expansion valve 1 shown in FIG. 1, the amount of refrigerant supplied from the expansion valve 1 to the evaporator 104 is automatically adjusted depending on the temperature and pressure of the refrigerant returning from the evaporator 104 to the expansion valve 1.

However, if the time constant of the power element 8 is relatively small, the hunting phenomenon is likely to occur, which may cause the valve body 3 to vibrate. In contrast, according to this embodiment, the axis X1 of the first flow path 21 is a straight line, and the valve body 3 or the valve body support 42 is arranged on the extension of the axis X1, or when the small path 21a is projected along the axis X1 of the first flow path 21 toward the valve chamber VS, the projected image overlaps the valve body 3 or the valve body support 42. Therefore, as shown by the arrow in FIG. 2, the refrigerant flowing out from the small path 21a to the valve chamber VS when the valve is opened hits the valve body 3 or the valve body support 42 from an oblique direction (i.e., a direction inclined with respect to the axis L), and the valve body 3 is given resistance by the fluid, thereby suppressing vibration. In particular, when the valve body 3 vibrates vertically, the refrigerant hits it obliquely, which can provide resistance when the valve body 3 moves upward, thereby achieving a high vibration suppression effect.

In addition, a small diameter passage 21a, which has a smaller diameter than the first flow passage 21 other than the small diameter passage 21a, is arranged at the refrigerant outlet of the first flow passage 21, so the throttling effect of the small diameter passage 21a increases the outflow speed of the refrigerant, and vibration of the valve body 3 can be suppressed more effectively.

(Modification)
Fig. 3 is a vertical cross-sectional view similar to Fig. 2, showing a modification of this embodiment. Fig. 4 is a perspective view showing a cover member 60 according to this modification. Since the other configurations are the same as those in the above-mentioned embodiment, the same reference numerals are used and duplicated explanations are omitted.

In this modified example, a cover member 60 is disposed between the valve body support 42 and the coil spring 41. As shown in FIG. 4, the cover member 60 has a cylindrical shape with a top, in which a peripheral wall 61 and a top wall 62 are connected, and a circular opening 63 is formed in the center of the top wall 62. The cover member 60 can be formed by press-molding a metal plate.

The valve body support 42 has a cylindrical main body 42a and a flange portion 42b extending radially outward from the main body 42a. When the cover member 60 is placed over the top of the coil spring 41, the lower surface of the top wall 62 comes into contact with the upper end of the coil spring 41, and the upper periphery of the coil spring 41 is surrounded by the peripheral wall 61. The valve body support 42 is then brought closer from above the cover member 60, and the main body 42a is fitted into the circular opening 63 and the inner periphery of the upper end of the coil spring 41, thereby completing the assembly. The top wall 62 of the cover member 60 is clamped and held between the upper end of the coil spring 41 and the flange portion 42b of the valve body support 42.

In this modified example, as shown in FIG. 3, the top of the coil spring 41 is covered by the cover member 60, so that the refrigerant flowing from the small diameter passage 21a toward the valve chamber VS flows along the smooth surface of the cover member 60, thereby suppressing the generation of turbulence, improving the vibration damping effect of the valve body 3, and suppressing the generation of abnormal noise.

Second Embodiment
3 is a vertical cross-sectional view of an expansion valve 1A according to the second embodiment. This embodiment differs from the first embodiment only in the shape of the first flow passage 21A of the valve body 2A. The other configurations are the same as those of the above-mentioned embodiment, so the same reference numerals are used and repeated explanations are omitted. In this embodiment, the first flow passage 21A other than the small diameter passage 21Aa constitutes the first passage, and the small diameter passage 21Aa constitutes the second passage.

In the first flow passage 21A of this embodiment, the axis X2 of the small diameter passage 21Aa intersects with the axis X1 of the first flow passage 21A other than the small diameter passage 21Aa. More specifically, the crossing angle θ2 between the axis X2 of the small diameter passage 21Aa and the axis L is smaller than the crossing angle θ1 between the axis X1 of the first flow passage 21A other than the small diameter passage 21Aa and the axis L. According to this embodiment, when the small diameter passage 21Aa is projected along the axis X2 onto the valve chamber VS side, the projected image overlaps with the valve body support 42. Note that the crossing angles θ1 and θ2 can be changed arbitrarily depending on the specifications of the expansion valve 1A. Therefore, the crossing angle θ1 may be smaller than the crossing angle θ2.

The axis X1 of the first flow passage 21A other than the small diameter passage 21Aa does not intersect with the inner circumference of the return flow passage 23, and the axis X2 of the small diameter passage 21Aa does not intersect with the inner circumference of the valve chamber VS. Therefore, by inserting a tool such as a drill obliquely with respect to the axis O, i.e., along the axis X1, into the return flow passage 23 from the outside of the third enlarged diameter hole 23e, it is possible to cut the first flow passage 21A other than the small diameter passage 21Aa. On the other hand, by inserting a tool such as a drill obliquely with respect to the axis L, i.e., along the axis X2, from below the opening that forms the valve chamber VS, it is possible to cut the small diameter passage 21Aa so that it connects to the first flow passage 21A.

According to this embodiment, when the valve is open, the refrigerant that flows out from the small diameter passage 21Aa to the valve chamber VS hits the valve body support 42 from an oblique direction, thereby suppressing vibration of the valve body 3. When suppressing vibration of the valve body 3, there are cases where the vibration suppression effect is greater if the refrigerant hits the valve body support 42 rather than the valve body 3. Therefore, by arbitrarily angling the small diameter passage 21Aa of the first flow path 21A, it is possible to direct the refrigerant to the optimal position.

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.

Reference Signs List 1, 1A: Expansion valve 2, 2A: Valve body 3: Valve element 4: Biasing device 5: Actuating rod 6: Ring spring 8: Power element 20: Valve seat 21, 21A: First flow path 22: Second flow path 23: Return flow path 27: Valve hole 41: Coil spring 42: Valve element support 43: Spring receiving member 50: Double pipe 60: Cover member 100: Refrigerant circulation system 101: Compressor 102: Condenser 104: Evaporator VS: Valve chamber

Claims (4)

An expansion valve capable of connecting a double pipe in which a low-pressure refrigerant passes through an inner pipe and a high-pressure refrigerant passes through an intermediate flow passage that is a space between an outer pipe arranged around the inner pipe and the inner pipe,
a valve body including a valve chamber having a valve seat, a valve through hole as a throttle connecting the valve chamber with a downstream side of the valve chamber , and a high-pressure flow passage connected from the intermediate flow passage to the valve chamber and through which a high-pressure refrigerant flows;
a valve body unit including a valve body that can be seated on the valve seat , a valve body support including a main body that supports the valve body and a flange portion formed on the main body ;
an actuating rod disposed in the valve through hole and in contact with the valve body;
A power element that drives the actuation rod;
a coil spring disposed on the opposite side of the power element with respect to the actuation rod and biasing the valve body unit toward the power element via the flange portion of the valve body support ;
the high-pressure flow passage is formed at an angle with respect to an axis of the valve body unit so that the high-pressure refrigerant that has flowed through the high-pressure flow passage from the intermediate flow passage toward the valve chamber hits the flange portion of the valve body support ,
When the high pressure flow passage is projected along an axis of the high pressure flow passage, the projected image overlaps with the flange portion of the valve body support in a valve closed state.
An expansion valve characterized by: 2. The expansion valve according to claim 1, further comprising a cover member having a top wall disposed between the flange portion of the valve body support and the coil spring, and a peripheral wall surrounding at least a portion of the periphery of the coil spring . the high pressure flow passage has a first passage on the outer pipe side and a second passage on the valve chamber side, the first passage having an inner diameter larger than an inner diameter of the second passage,
When the second passage is projected along an axis of the second passage, the projected image overlaps with the flange portion of the valve body support in a valve closed state.
3. The expansion valve according to claim 1 or 2 . The axis of the first passage and the axis of the second passage intersect.
4. The expansion valve according to claim 3 .

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