JP2020143855A - Expansion valve - Google Patents

Abstract

To provide an expansion valve which is low cost and which can manage the amount of a valve opening stroke with good accuracy.SOLUTION: An expansion valve includes: a valve body 2 arranged in a flow passage in which a fluid passes and including an annular valve seat 20 and an orifice part 27; a valve element 3 for limiting the passing of the fluid by being seated in the valve seat 20, and for allowing the fluid to pass by being separated from the valve seat 20; a coil spring 41 for energizing the valve element 3 toward the valve seat 20; and an operation rod 5 which is inserted in the orifice part 27, and whose one end comes into contact with the valve element 3. The operation rod 5 includes a first step surface 5d extending in the direction crossing an axis line. The valve body 2 includes a second step surface 29 opposing to the first step surface 5d. When the operation rod 5 displaces in the direction for separating the valve element 3 from the valve seat 20 against the energization force of the coil spring 41, the first step surface 5d comes into contact with the second step surface 29; thereby, the displacement of the operation rod 5 is restricted.SELECTED DRAWING: Figure 2

Description

The present invention relates to an expansion valve.

Conventionally, a temperature-sensitive expansion valve that adjusts the amount of refrigerant passing through according to the temperature has been used for a refrigeration cycle used in an air conditioner or the like mounted on an automobile.

For example, the expansion valve shown in Patent Document 1 has an inlet port into which a high-pressure refrigerant is introduced and a valve chamber communicating with the inlet port, and a valve member drive mechanism called a power element is provided at the top of the valve body. Equipped. The spherical valve body arranged in the valve chamber faces the valve seat that opens in the valve chamber, and is operated by an operating rod driven by a power element to control the opening of the throttle passage between the valve seat and the valve seat. To do.

The power element is composed of an upper lid member that forms a pressure operating chamber, a thin plate diaphragm that elastically deforms under pressure, and a disk-shaped receiving member. Further, the working gas is sealed in the pressure working chamber formed by the upper lid member and the diaphragm. Further, a stopper member is sandwiched between the diaphragm and the receiving member.

Here, when the internal pressure of the pressure operating chamber is relatively increased, the diaphragm is deformed so as to expand the pressure operating chamber, whereby the stopper member is pushed to press the operating rod and separate the valve body from the valve seat. .. On the other hand, when the internal pressure of the pressure operating chamber drops relatively, the deformation of the diaphragm returns and the pressing force of the operating rod disappears, so that the valve body sits on the valve seat.

Japanese Unexamined Patent Publication No. 2017-198373

By the way, if there is no manufacturing error in each part, the valve opening stroke amount of the valve body is determined by the design value, but in reality, the valve opening stroke amount varies due to the manufacturing error of each part. However, if the valve opening stroke amount becomes too large, the durability of the thin plate diaphragm is lowered.

Therefore, conventionally, after assembling the expansion valve, the valve opening stroke amount is measured and inspected, and if the valve opening stroke amount exceeds the specified value, it is disassembled and reassembled. However, if reassembly is performed frequently, there is a problem that the cost of the expansion valve increases.

On the other hand, if the manufacturing tolerance of each part of the expansion valve is strictly controlled, the valve opening stroke amount can be kept within the specified value, but the cost of the part increases, and as a result, the cost of the expansion valve also increases. Increase.

Therefore, the present invention is to provide an improved expansion valve capable of accurately controlling the valve opening stroke amount at a low cost.

In order to achieve the above object, the expansion valve according to the present invention is
A valve body with a valve seat and an orifice,
A valve body that restricts the passage of fluid by sitting on the valve seat and allows the passage of the fluid by separating from the valve seat.
A coil spring that urges the valve body toward the valve seat,
It has an operating rod that is inserted through the orifice portion and has one end abutted against the valve body.
The actuating rod comprises a first contact surface extending in a direction intersecting the axis.
The valve body includes a second contact surface facing the first contact surface.
When the operating rod is displaced in a direction that separates the valve body from the valve seat against the urging force of the coil spring, the first contact surface and the second contact surface come into contact with each other. , The displacement of the operating rod is limited.

According to the present invention, the valve opening stroke amount can be accurately controlled at a low cost.

FIG. 1 is a schematic cross-sectional view schematically showing an example in which the expansion valve 1 in the present embodiment is applied to a refrigerant circulation system. FIG. 2 is an enlarged cross-sectional view showing the periphery of the lower end of the valve body 3 and the operating rod 5 in the expansion valve 1 of FIG. FIG. 3 is a graph showing the flow rate of the refrigerant passing through the orifice portion 27 on the vertical axis and the valve opening stroke amount of the operating rod 5 on the horizontal axis.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

(Definition of direction)
In the present specification, the direction from the valve body 3 toward the operating rod 5 is defined as "upward", and the direction from the operating rod 5 toward the valve body 3 is defined as "downward". Therefore, in the present specification, the direction from the valve body 3 toward the operating rod 5 is referred to as "upward" regardless of the posture of the expansion valve 1.

(Overview of expansion valve)
The outline of the expansion valve 1 in the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view schematically showing an example in which the expansion valve 1 in the present embodiment is applied to the refrigerant circulation system 100. FIG. 2 is an enlarged cross-sectional view showing the periphery of the lower end of the valve body 3 and the operating rod 5 in the expansion valve 1 of FIG. In this embodiment, the expansion valve 1 is fluidly connected to the compressor 101, the condenser 102, and the evaporator 104.

In FIG. 1, the expansion valve 1 includes a valve body 2 having a valve chamber VS, a valve body 3, an urging device 4, and an operating rod 5.

The valve body 2 includes a first flow path 21 and a second flow path 22 in addition to the valve chamber VS. The first flow path 21 is a supply-side flow path, and a refrigerant (also referred to as 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, and the fluid in the valve chamber VS is discharged to the outside of the expansion valve via the orifice portion 27 and the discharge side flow path. The first flow path 21 and the valve chamber VS are communicated with each other by a connecting path 21a having a smaller diameter than the first flow path 21.

In FIG. 1, the valve body 3 is arranged in the valve chamber VS. When the valve body 3 is seated on the annular valve seat 20 of the valve body 2, the flow of the refrigerant in the orifice portion 27 is restricted. This state is called a non-communication state. On the other hand, when the valve body 3 is separated from the valve seat 20, the flow of the refrigerant passing through the orifice portion 27 increases. This state is called a communication state.

In FIGS. 1 and 2, the operating rod 5 is formed by, for example, cutting a cylindrical member made of SUS. In the operating rod 5, the small diameter shaft portion 5a, the medium diameter shaft portion 5b, and the large diameter shaft portion 5c are coaxially provided in this order from the lower end side. The medium-diameter shaft portion 5b and the large-diameter shaft portion 5c are connected by a first stepped surface (also referred to as a first contact surface) 5d extending in a direction orthogonal to the axis X. The small diameter shaft portion 5a and the medium diameter shaft portion 5b are connected by a tapered surface.

In the valve body 2, a diameter-expanded portion 26 having a diameter larger than that of the large-diameter shaft portion 5c is formed around the first stepped surface 5d. The upper end of the enlarged diameter portion 26 communicates with the return flow path 23. The lower end of the enlarged diameter portion 26 communicates with the sliding hole 28 having a smaller diameter than the large diameter shaft portion 5c.

The medium-diameter shaft portion 5b of the operating rod 5 is inserted into the sliding hole 28 so that both can slide. The sliding hole 28 and the enlarged diameter portion 26 are connected by a second stepped surface (also referred to as a second contact surface) 29 extending in a direction orthogonal to the axis X. The second stepped surface 29 faces the first stepped surface 5d.

The small diameter shaft portion 5a is inserted through the cylindrical orifice portion 27 with a gap. The lower end of the operating rod 5 is in contact with the upper surface of the valve body 3.

The operating rod 5 can press the valve body 3 in the valve opening direction against the urging force of the urging device 4.

In FIG. 1, the urging device 4 has a coil spring 41 in which a wire rod having a circular cross section is spirally wound, 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 a spherical valve body 3 is welded to the upper surface thereof, and both are integrated.

The spring receiving member 43 that supports the lower end of the coil spring 41 is screwable with respect to the valve body 2, and has a function of sealing the valve chamber VS and a function of adjusting the urging force of the coil spring 41. ..

The power element 8 provided at the upper end of the valve body 2 has a stopper 81, an upper lid member 82, a diaphragm 83, a stopper member 84, and a receiving member 85.

An opening 82a is formed at the top of the substantially conical upper lid member 82, and can be sealed by a stopper 81.

The diaphragm 83 is made of a thin plate material in which a plurality of concentric uneven shapes are formed, and has an outer diameter substantially the same as the outer diameter of the upper lid member 82 and the receiving member 85.

The substantially cylindrical receiving member 85 whose upper portion extends in a conical shape has a male screw 85a on the outer periphery of its lower end.

The stopper member 84 has a disk portion 84a and a cylindrical portion 84b coaxially joined to the lower surface of the disk portion 84a. A fitting hole 84c is formed in the center of the lower end of the cylindrical portion 84b.

The procedure for assembling the power element 8 will be described. In a state where the outer peripheral portions of the upper lid member 82, the diaphragm 83, and the receiving member 85 are overlapped with each other, the outer peripheral portions are peripherally welded by, for example, TIG welding, laser welding, plasma welding, or the like to be integrated.

Subsequently, the working gas is sealed in the space (referred to as the pressure working chamber PA) surrounded by the upper lid member 82 and the diaphragm 83 from the opening 82a formed in the upper lid member 82, and then the opening 82a is sealed with the stopper 81. Further, the stopper 81 is fixed to the upper lid member 82 by projection welding or the like.

At this time, since the diaphragm 83 receives pressure in the form of projecting toward the receiving member 85 due to the working gas sealed in the pressure operating chamber PA, the stopper arranged in the lower space LS surrounded by the diaphragm 83 and the receiving member 85. It is supported in contact with the upper surface of the member 84. Since the disk portion 84a of the stopper member 84 is held by the inner surface of the receiving member 85, the stopper member 84 does not come out of the power element 8.

When assembling the power element 8 assembled as described above to the valve body 2, the male screw 85a on the outer periphery of the lower end of the receiving member 85 is screwed into the female screw 2b formed on the inner circumference of the recess 2a of the valve body 2. When the male screw 85a is screwed into the female screw 2b, the lower end of the receiving member 85 comes into contact with the upper end surface of the valve body 2. As a result, the power element 8 can be fixed to the valve body 2. In such a state, the lower space LS of the power element 8 communicates with the return flow path 23, that is, has the same internal pressure.
At this time, a packing PK is interposed between the power element 8 and the valve body 2 to prevent the refrigerant from leaking from the recess 2a when the power element 8 is attached to the valve body 2.

(Operation of expansion valve)
An operation example of the expansion valve 1 will be described with reference to FIG. The refrigerant pressurized by the compressor 101 is liquefied by the condenser 102 and sent to the expansion valve 1. Further, the refrigerant adiabatically expanded by the expansion valve 1 is sent to the evaporator 104, and the evaporator 104 exchanges heat with the air flowing around the evaporator. The refrigerant returning from the evaporator 104 is returned to the compressor 101 side through the expansion valve 1 (more specifically, the return flow path 23). At this time, by passing through the evaporator 104, the fluid pressure in the second flow path 22 becomes larger than the fluid pressure in the return flow path 23.

A high-pressure refrigerant is supplied to the expansion valve 1 from the condenser 102. More specifically, the high-pressure refrigerant from the condenser 102 is supplied to the valve chamber VS via the first flow path 21.

When the valve body 3 is seated on the valve seat 20 (in a non-communication state), the flow rate of the refrigerant sent from the valve chamber VS to the evaporator 104 through the orifice portion 27 and the second flow path 22 is limited. Will be done. On the other hand, when the valve body 3 is separated from the valve seat 20 (in the state of communication), the flow rate of the refrigerant sent from the valve chamber VS to the evaporator 104 through the orifice portion 27 and the second flow path 22. Increases. Switching between the closed state and the open state of the expansion valve 1 is performed by the operating rod 5 connected to the power element 8.

In FIG. 1, a pressure operating chamber PA partitioned by a diaphragm 83 and a lower space LS are provided inside the power element 8. Therefore, when the working gas in the pressure working chamber PA is liquefied, the working rod 5 moves upward, and when the liquefied working gas is vaporized, the working rod 5 moves downward. In this way, the expansion valve 1 is switched between the open state and the closed state.

Further, the lower space LS of the power element 8 communicates with the return flow path 23. Therefore, the volume of the working gas in the pressure working chamber PA changes according to the pressure of the refrigerant flowing through the return flow path 23, and the working rod 5 is driven. In other words, in the expansion valve 1 shown in FIG. 1, the amount of the refrigerant supplied from the expansion valve 1 toward the evaporator 104 is automatically adjusted according to the pressure of the refrigerant returning from the evaporator 104 to the expansion valve 1. To.

Next, the effect of providing the first stepped surface 5d on the operating rod 5 will be described. As described above, the deformation of the diaphragm 83 pushes the operating rod 5 downward through the stopper member 84, and the valve body 3 is separated from the valve seat 20. The amount of movement of the operating rod 5 in the axial direction at the time of valve opening is referred to as the valve opening stroke amount.

FIG. 3 is a graph showing the flow rate of the refrigerant passing through the orifice portion 27 on the vertical axis and the valve opening stroke amount of the operating rod 5 on the horizontal axis, and shows the valve opening characteristics of the expansion valve 1. Here, with the valve body 3 seated on the valve seat 20, the valve opening stroke amount is 0, and the flow rate of the refrigerant passing through the orifice portion 27 at that time is also set to 0.

When the valve opening stroke amount is relatively small, as the valve opening stroke amount increases, the flow rate of the refrigerant passing through the orifice portion 27 increases substantially linearly, and thereafter, the rate of increase of the refrigerant flow rate with respect to the valve opening stroke amount increases. descend. Here, when the flow rate of the refrigerant required to exert the function of the expansion valve 1 is the required maximum flow rate MX, the design stroke amount SX corresponding to at least the required maximum flow rate MX is determined according to the valve opening characteristics of FIG. It is necessary to hold it on the operating rod 5.

By the way, the valve opening stroke amount of the operating rod 5 is related to the deformation amount of the diaphragm 83. However, a plurality of parts are interposed from the valve body 3 to the diaphragm 83 of the power element 8. Therefore, the maximum amount of deformation of the diaphragm 83 may change due to variations in the accuracy of the plurality of parts.

Here, with reference to FIG. 1, a reference example in which the outer diameters of the medium-diameter shaft portion 5b and the large-diameter shaft portion 5c are the same and the first stepped surface is not provided will be examined. First, since the diaphragm 83 is a thin metallic plate, suppressing the amount of deformation greatly affects the durability. For example, when the valve is closed, the diaphragm 83 is deformed upward (deformation amount + Δ), while when the valve is opened, the diaphragm 83 is deformed downward by the same amount (deformation amount −Δ). Then, since the amount of deformation of the diaphragm 83 stays within | ± Δ |, the maximum internal stress is reduced and the durability can be improved. The maximum valve opening stroke amount of the operating rod 5 at this time is 2.Δ.

Therefore, it is considered that the relative position of the lower end of the operating rod 5 with respect to the valve seat 20 is accurately adjusted so that the valve is closed while the deformation amount + Δ of the diaphragm 83 is maintained.

In FIG. 1, the distance from the valve seat 20 to the upper surface of the valve body 2 is A, the plate thickness of the receiving member 85 is B, the gap between the receiving member 85 and the disk portion 84a of the stopper member 84 is C, and the operating rod. When the total length of 5 is D, the distance between the lower surface of the disk portion 84a and the bottom surface of the fitting hole 84c is E, and the distance between the upper end of the valve body 3 and the contact point of the valve seat 20 is F, the valve closing relative In order to adjust the position accurately, it is necessary to set (A + B + C) = (D + E + F).

However, since the stopper member 84 is a single component, E can be regarded as substantially constant, assuming that the dimensional relationship between the disk portion 84a and the fitting hole 84c is formed with high accuracy. Further, since the valve body 3 is spherical, F can be considered to be substantially constant, assuming that the valve body 3 is formed with high accuracy.

Then, in order to accurately adjust the relative position of the lower end of the operating rod 5 with respect to the valve seat 20, it is necessary to accurately manufacture each component so that the distances A, B, C, and D become the specified values. However, there are always manufacturing tolerances in the parts.

If the distances A, B, and C are the upper limit of the positive manufacturing tolerance and the distance D is the lower limit of the negative manufacturing tolerance, according to the combination, the diaphragm 83 is further deformed from the position of the deformation amount + Δ when the valve is closed. The state is shifted downward by the error (-α). Therefore, when the valve is opened, the maximum amount of deformation of the diaphragm 83 becomes | − (Δ + α) |, and the maximum internal stress of the diaphragm 83 increases.

On the contrary, when the distances A, B, and C are the lower limit of the negative manufacturing tolerance and the distance D is the upper limit of the positive manufacturing tolerance, according to the combination, the diaphragm 83 is deformed when the valve is closed. The position is further shifted upward by an error (+ α) from the position of + Δ, the maximum amount of deformation of the diaphragm 83 becomes | + (Δ + α) |, and the maximum internal stress of the diaphragm 83 also increases.

In order to solve such a problem, the operating rod 5 of the present embodiment is provided with a first stepped surface 5d. According to the present embodiment, when the first stepped surface 5d comes into contact with the second stepped surface 29 at the time of valve opening, further movement, that is, the maximum valve opening stroke amount can be suppressed.

The valve opening stroke amount can be reduced by β by the contact between the first step surface 5d and the second step surface 29. Then, in the above reference example, the maximum valve opening stroke amount of the operating rod 5 was 2.Δ, whereas in the present embodiment, the maximum valve opening stroke amount of the operating rod 5 was set to (2), as shown in FIG.・ It can be suppressed to Δ−β). As a result, the maximum amount of deformation of the diaphragm 83 can be suppressed to | ± (Δ−β / 2) |, so that the durability of the diaphragm 83 is improved.

On the other hand, in order to secure the function of the expansion valve 1, it is necessary to set the maximum valve opening stroke amount (2.Δ−β) of the operating rod 5 to be equal to or larger than the design stroke amount SX. Specifically, when the first stepped surface 5d comes into contact with the second stepped surface 29, the protrusion amount of the operating rod 5 should be equal to or greater than the design stroke amount SX. Consider the manufacturing tolerances of the parts for that purpose.

Here, in FIG. 2, the distance between the upper end of the valve body 3 and the contact point of the valve seat 20 is F, the distance from the second step surface 29 to the valve seat 20 is G, and the operating rod 5 is from the first step surface 5d. If the distance to the lower end of is H, then SX ≦ (F + HG) should be set. As described above, since the valve body 3 is spherical, it can be considered that F is substantially constant, assuming that it is formed with high accuracy.

Therefore, when the first stepped surface 5d comes into contact with the second stepped surface 29, the protrusion amount of the operating rod 5 is set to be equal to or larger than the design stroke amount SX, and the difference γ from the design stroke amount SX (FIG. 3). Only the combination of manufacturing tolerances of distances G and H needs to be managed so that In other words, in the reference example, it was necessary to manage the manufacturing tolerances of four places, but in this embodiment, it is sufficient to manage the manufacturing tolerances of two places, so that the manufacturing process and inspection of the parts are performed. It is possible to save labor in the process and secure cost reduction.

The present invention is not limited to the above-described embodiment. Within the scope of the present invention, any component of the above-described embodiment can be modified. Further, in the above-described embodiment, any component can be added or omitted.

1: Expansion valve 2: Valve body 3: Valve body 4: Evaporating device 5: Actuating rod 6: Ring spring 8: Power element 20: Valve seat 21: First flow path 22: Second flow path 23: Return flow path 26: Expanded diameter 27: orifice 41: Coil spring 42: Valve body support 43: Spring receiving member 100: Refrigerant circulation system 101: Compressor 102: Capacitor 104: Evaporator VS: Valve chamber

Claims (3)

A valve body with a valve seat and an orifice,
A valve body that restricts the passage of fluid by sitting on the valve seat and allows the passage of the fluid by separating from the valve seat.
A coil spring that urges the valve body toward the valve seat,
It has an operating rod that is inserted through the orifice portion and has one end abutted against the valve body.
The actuating rod comprises a first contact surface extending in a direction intersecting the axis.
The valve body includes a second contact surface facing the first contact surface.
When the operating rod is displaced in a direction that separates the valve body from the valve seat against the urging force of the coil spring, the first contact surface and the second contact surface come into contact with each other. , The displacement of the working rod is limited,
An expansion valve characterized by that. It has a power element including a diaphragm and a stopper member that abuts on the diaphragm.
The other end of the operating rod is in contact with the stopper member.
The expansion valve according to claim 1, wherein the expansion valve is characterized in that. The second contact surface faces the power element side.
The expansion valve according to claim 2, wherein the expansion valve is characterized in that.

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