JP2006266568A - Expansion valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a diaphragm without requiring addition of a part to a power element or machining in a thermal expansion valve. <P>SOLUTION: A shape of an upper housing 21 constituting a temperature sensing chamber is formed to be a stopper part 30 approaching to a diaphragm position when a valve part 2 is fully closed, and an over stroke amount of the diaphragm 23 is regulated. A position of a center pressure receiving part 29 of the diaphragm 23 when the valve part 2 is fully closed is set to be near a plane including a welded part of an outer periphery of the diaphragm 23, and a corrugated part 28 of the diaphragm 23 is prevented from inducing reverse operation at the time of opening and closing operation of the valve part 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an expansion valve, and in particular, detects the temperature and pressure of an outlet refrigerant of an evaporator in a refrigeration cycle of an automotive air conditioner system, and controls the flow rate of the refrigerant supplied to the evaporator according to the temperature and pressure of the refrigerant. Relates to a temperature-type expansion valve.

  In an automotive air conditioner system, high-temperature and high-pressure gas refrigerant compressed by a compressor is condensed by a condenser, and the liquid refrigerant separated from the gas and liquid by a receiver / dryer is adiabatically expanded by an expansion valve to obtain a low-temperature and low-pressure refrigerant. A refrigeration cycle is formed in which it is evaporated by an evaporator and returned to the compressor. In an evaporator to which a low-temperature refrigerant is supplied, cooling is performed by heat exchange between the air in the passenger compartment and the refrigerant.

  As such an expansion valve, a so-called temperature-type expansion valve is widely used in which the flow rate of the refrigerant is controlled by opening and closing the valve rod in accordance with the temperature and pressure of the low-pressure refrigerant sent from the evaporator.

  The temperature type expansion valve includes a power element that senses the temperature and pressure of the refrigerant at the outlet of the evaporator, and a valve unit that controls the flow rate of the refrigerant sent to the evaporator in accordance with the temperature and pressure sensed by the power element. Here, the configuration of the power element will be described.

  7 is a central longitudinal sectional view showing the configuration of a power element of a conventional expansion valve, FIG. 8 is a diagram showing the spring characteristics of a diaphragm used in the power element of the conventional expansion valve, and FIG. 9 is a diaphragm at the time of overstroke. It is a figure which shows the state of.

  As shown in FIG. 7, the power element 101 includes a thick metal upper housing 102 and a lower housing 103, and a diaphragm 104 made of a thin thin metal plate that is arranged so as to partition a space surrounded by the upper housing 102 and the lower housing 103. And. The outer peripheral edge of the diaphragm 104 is welded together with the outer peripheral edges of the upper housing 102 and the lower housing 103. The diaphragm 104 constitutes a temperature sensing chamber in which a temperature sensing gas is sealed between the upper housing 102 and the lower housing 103 constitutes a space for introducing the refrigerant at the evaporator outlet so as to contact the diaphragm 104. Yes.

  The diaphragm 104 includes a central pressure receiving portion 105 that senses and displaces pressure, and a concentric corrugated portion 106 that is formed so that the central pressure receiving portion 105 can be displaced in a direction perpendicular to the surface. As shown in FIG. 8, the diaphragm 104 has a neutral position on the plane including the weld position between the upper housing 102 and the lower housing 103, and the center pressure receiving portion 105 responds to fluctuations in pressure applied to the diaphragm 104. Thus, it is displaced in the vertical direction in the figure around the neutral position. This displacement is transmitted to the valve unit to drive the valve unit to open and close. Since the valve portion is arranged to open and close in the same axial direction as the power element 101, the stroke in which the diaphragm 104 is displaced up and down is directly the opening and closing stroke of the valve portion. However, since the valve portion does not stroke at the fully closed position in the stroke in the valve closing direction, only the diaphragm 104 overstrokes upward in the drawing. As shown in FIG. 9, the upper limit of the overstroke of the diaphragm 104 is restricted by the central pressure receiving portion 105 of the diaphragm 104 coming into contact with the inner wall of the upper housing 102.

  In such a power element 101, a thin metal plate diaphragm 104 is fixed to the upper housing 102 and the lower housing 103 by welding the outer periphery thereof. Since the diaphragm 104 is susceptible to the influence of welding heat at the welded part, the welded part is greatly affected by an overstroke that exceeds the valve operating range and operates regardless of the movement of the valve part. Tensile stress is applied.

  On the other hand, an expansion valve is known in which the amount of overstroke after valve closing is regulated (see, for example, Patent Document 1). This expansion valve is provided with a diaphragm amplitude regulating plate between the upper housing and the diaphragm, and this diaphragm amplitude regulating plate regulates the amount of overstroke to prevent unnecessary stress from being applied to the welded portion. Durability is improved.

  Further, when the diaphragm is stroked, the position close to the welded portion serves as an operating fulcrum, but also in this case, tensile stress and compressive stress are repeatedly applied to the welded portion when the valve portion is opened and closed.

On the other hand, an expansion valve is known in which the operating fulcrum of the diaphragm is moved to a place where it is difficult to be affected by the heat of the welded part. According to a certain expansion valve, the protrusions are provided inside the upper housing and the lower housing, and the protrusions are sandwiched and supported by the protrusions, so that the sandwiched position serves as the operation fulcrum of the diaphragm. Stress is not applied to the portion (for example, see Patent Document 2). Further, according to another expansion valve, an operation fulcrum of the diaphragm is provided by sandwiching a reinforcing ring between the welded portion of the lower housing and the diaphragm and making the inner diameter of the reinforcing ring smaller than the inner diameter of the diaphragm supporting portion of the lower housing. The inner diameter of the reinforcing ring is far from the heat-affected portion during welding (for example, see Patent Document 3). Further, according to another expansion valve, a ring is sandwiched between the lower housing and the diaphragm, and the inner diameter of the ring is used as an operating fulcrum of the diaphragm so as to be away from the heat-affected portion during welding (for example, patents). Reference 4). In this way, the diaphragm's operating fulcrum is kept away from the heat-affected portion during welding, thereby improving the durability of the diaphragm.
JP-A-5-133646 Japanese Utility Model Publication No. 6-32973 JP-A-7-133972 JP-A-9-79703

  However, in the conventional expansion valve, the neutral position of the diaphragm is set at the center of the range of use of the valve section where the central pressure receiving section that senses and displaces the pressure is set, so every time the central pressure receiving section moves up and down the neutral position. The corrugated portion of the diaphragm causes a reversal operation, which causes the tensile stress and the compressive stress to be alternately applied to the diaphragm fulcrum, thereby reducing the durability of the diaphragm. . In addition, in order to keep the diaphragm fulcrum away from the heat-affected part during welding, the upper housing and the lower housing are processed to provide protrusions, and some parts are added, which increases the cost. was there.

  The present invention has been made in view of these points, and an object of the present invention is to provide an expansion valve in which the durability of the diaphragm is improved without requiring any additional parts or processing.

  In the present invention, in order to solve the above problem, a power element that senses the temperature and pressure of the refrigerant introduced from the evaporator, and a valve unit that controls the flow rate of the refrigerant supplied to the evaporator according to the temperature and pressure of the refrigerant. And an expansion valve formed by welding the outer peripheral edge portions of the first housing and the second housing, which are disposed on both sides of the diaphragm with the diaphragm, together with the diaphragm. The outer periphery of the first housing constituting the diaphragm constitutes a stopper portion that regulates the amount of overstroke of the diaphragm, and the diaphragm is welded to the diaphragm when the central pressure receiving portion is fully closed. An expansion valve characterized by being set to be located in the vicinity of a plane including It is subjected.

  According to such an expansion valve, when the diaphragm has an overstroke that displaces in the valve closing direction after the valve portion is fully closed, the diaphragm abuts against the stopper portion, and the overstroke amount beyond that is regulated. The diaphragm fulcrum is not subjected to a large stress, and the diaphragm's corrugated portion is configured by setting the position of the central pressure receiving portion of the diaphragm in the vicinity of the plane including the welded portion of the diaphragm when the valve portion is fully closed. Since no reverse operation occurs, cracks generated in the corrugated portion can be drastically reduced, so that the durability of the diaphragm can be improved.

  In the expansion valve according to the present invention, the shape of the first housing that constitutes the temperature sensitive room is made a shape in which the overstroke amount of the diaphragm is regulated, so that a special part is added or the first housing is processed. This eliminates the need for this, and since there is little generation of stress due to a large overstroke of the diaphragm, there is an advantage that the manufacturing cost of the expansion valve can be reduced and the durability of the diaphragm can be improved. Further, since the reversing operation is not caused to occur in the corrugated portion of the diaphragm, it is possible to prevent the corrugating portion from being deteriorated due to the reversing operation, thereby greatly improving the durability of the diaphragm.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a central longitudinal sectional view showing the overall configuration of an expansion valve according to the present invention.
This expansion valve includes a power element 1 shown in the upper part of the figure and a valve part 2 shown in the lower part of the figure. The valve unit 2 has a port 12 for receiving a high-temperature / high-pressure liquid refrigerant from a receiver / dryer on the side of the body 11 and a port for supplying low-temperature / low-pressure refrigerant squeezed and expanded by the valve unit 2 to the evaporator. 13, a port 14 for receiving the refrigerant evaporated from the evaporator, and a port 15 for returning the refrigerant that has passed through the valve portion 2 to the compressor.

  A valve seat 16 is formed integrally with the body 11 in the fluid passage communicating from the port 12 to the port 13, and a ball-shaped valve body 17 is disposed on the upstream side of the valve seat 16. In a space in which the valve body 17 is accommodated, a spring 18 is disposed to urge the valve body 17 in a direction in which the valve body 17 is seated on the valve seat 16, and the spring 18 is received by a spring receiving member 19. The spring receiving member 19 is fitted to an adjustment screw 20 screwed to the lower end portion of the body 11 so that the load of the spring 18 can be adjusted by adjusting the screwing amount of the adjustment screw 20 into the body 11. I have to.

  The power element 1 provided at the upper end of the body 11 is disposed on the lower surface of the diaphragm 23 in the figure, and the upper housing 21, the lower housing 22, a diaphragm 23 disposed so as to partition the space surrounded by these. Disc 24. A temperature sensing gas sealed with the upper housing 21 and the diaphragm 23 is filled with a temperature sensing gas.

  A shaft 25 that transmits the displacement of the diaphragm 23 to the valve body 17 is disposed below the disk 24. The upper portion of the shaft 25 is held by a holder 26 that is suspended across a fluid passage that communicates between the ports 14 and 15. The holder 26 is provided with a spring 27 that applies a lateral load to the upper end portion of the shaft 25 so as to suppress vibration in the longitudinal direction of the shaft 25 due to pressure fluctuation of the high-pressure refrigerant.

  In the expansion valve configured as described above, the power element 1 senses the pressure and temperature of the refrigerant returned from the evaporator to the port 14, and when the refrigerant temperature is high or low, the valve element 17 is moved in the valve opening direction. On the contrary, when the temperature is low or the pressure is high, the valve element 17 is moved in the valve closing direction to control the opening degree of the valve portion 2. On the other hand, the liquid refrigerant supplied from the receiver / dryer flows into the space where the valve body 17 is located through the port 12 and is squeezed and expanded by passing through the valve portion 2 whose opening degree is controlled. Become a refrigerant. The refrigerant exits from the port 13 and is supplied to the evaporator, where it exchanges heat with the air in the passenger compartment and returns to the port 14 of the expansion valve. At this time, the expansion valve controls the flow rate of the refrigerant supplied to the evaporator so that the refrigerant at the outlet of the evaporator has a predetermined degree of superheat, so that the refrigerant is returned to the compressor in a state where the refrigerant is completely evaporated.

FIG. 2 is an explanatory diagram showing the housing shape and diaphragm of the power element, and FIG. 3 is a diagram showing the spring characteristics of the diaphragm.
In the power element 1, the upper housing 21 is changed from a conventional shape shown by a chain line in FIG. 2 to a shape shown by a solid line for reference. That is, the upper housing 21 has a stopper 30 as a region corresponding to the vicinity of the outer periphery of the corrugated portion 28 and the central pressure receiving portion 29 that detects and displaces pressure from the outer periphery of the diaphragm 23, and this stopper portion 30 is used as a welded portion of the diaphragm 23. It is formed so as to be displaced toward the diaphragm 23 to a position close to a plane including Thereby, when the diaphragm 23 is displaced in the valve closing direction of the valve portion 2 regardless of the opening / closing operation of the valve portion 2, the central pressure receiving portion 29 of the diaphragm 23 comes into contact with the stopper portion 30. The overstroke amount can be regulated.

  Further, the diaphragm 23 is set so that the central pressure receiving portion 29 is positioned on a plane including the welded portion when the valve portion 2 is fully closed. As a result, as shown in FIG. 3, the neutral position of the diaphragm 23 becomes the fully closed position of the valve portion 2, which is the upper limit of the use range of the expansion valve, and the diaphragm 23 is closer to the valve portion 2 than the neutral position. Will be displaced. Therefore, as long as the diaphragm 23 is displaced within the range of use, the corrugated portion 28 does not cause a reversal operation, and tensile stress and compressive stress are alternately applied to the operating fulcrum of the diaphragm 23. Therefore, the durability of the diaphragm 23 can be improved.

Next, the displacement state of the diaphragm 23 when the expansion valve configured as described above operates will be described.
4 is an explanatory view showing the state of the main part when the valve part is in the fully open state, FIG. 5 is an explanatory view showing the state of the main part when the valve part is in the fully closed state, and FIG. It is explanatory drawing showing the state of the principal part when it exists in an overstroke state.

  First, when the temperature of the refrigerant returned from the evaporator is sufficiently high or the pressure of the refrigerant is sufficiently low, the diaphragm 23 of the power element 1 is displaced toward the valve portion 2 as shown in FIG. Thus, the downward displacement in the figure is regulated by the disk 24 that is in contact with the horizontal portion of the lower housing 22. At this time, the disk 24 is located at the lowest valve portion 2 side of the movable range, that is, the lowermost side in the drawing, so that the valve body 17 of the valve portion 2 is also at the lowest position in the drawing via the shaft 25. The valve portion 2 is fully open.

  Here, when the temperature of the refrigerant returned from the evaporator is lowered by continuing the operation of the refrigeration cycle, the pressure in the sensation greenhouse decreases, so the diaphragm 23 is displaced upward in the figure. . Along with this, the valve element 17 urged in the valve closing direction by the spring 18 also moves upward in the figure, and the opening degree of the expansion valve becomes smaller.

  When the temperature of the refrigerant returned from the evaporator is further lowered, finally, as shown in FIG. 5, the valve element 17 is seated on the valve seat 16 and the expansion valve is fully closed. At this time, the diaphragm 23 is in its neutral position, and the central pressure receiving portion 29 is substantially located on a plane passing through the welded portion on the outer periphery of the diaphragm 23. As described above, the central pressure receiving portion 29 of the diaphragm 23 is always displaced below the neutral position of the diaphragm 23 from the fully open state to the fully closed state of the valve portion 2. Accordingly, since the corrugated portion 28 of the diaphragm 23 does not reverse within the operating range of the expansion valve, cracks generated in the corrugated portion 28 due to the reversing operation of the corrugated portion 28 are drastically reduced. Since the generation of the tensile stress and the compressive stress applied to the operating fulcrum 23 is drastically reduced, the durability of the diaphragm 23 can be greatly increased.

  When the temperature of the refrigerant returned from the evaporator is further lowered, the valve body 17 is already seated on the valve seat 16 and cannot go further upward in the figure, so that only the diaphragm 23 is displaced upward in the figure. Become. At this time, the diaphragm 23 abuts against the stopper portion 30 of the upper housing 21 located close to the neutral position, so that no further overstroke occurs. For this reason, the corrugated portion 28 of the diaphragm 23 does not perform a reversing operation, and a large stress is not generated at the operating fulcrum of the diaphragm 23, so that the durability of the diaphragm 23 can be improved.

It is a center longitudinal cross-sectional view which shows the whole structure of the expansion valve by this invention. It is explanatory drawing which shows the housing shape and diaphragm of a power element. It is a figure which shows the spring characteristic of a diaphragm. It is explanatory drawing showing the state of the principal part when a valve part exists in a full open state. It is explanatory drawing showing the state of the principal part when a valve part is in a fully closed state. It is explanatory drawing showing the state of the principal part when a diaphragm is in an overstroke state. It is a center longitudinal cross-sectional view which shows the structure of the power element of the conventional expansion valve. It is a figure which shows the spring characteristic of the diaphragm used for the power element of the conventional expansion valve. It is a figure which shows the state of the diaphragm at the time of an overstroke.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power element 2 Valve part 11 Body 12, 13, 14, 15 Port 16 Valve seat 17 Valve body 18 Spring 19 Spring receiving member 20 Adjustment screw 21 Upper housing 22 Lower housing 23 Diaphragm 24 Disc 25 Shaft 26 Holder 27 Spring 28 Corrugated part 29 Central pressure receiving part 30 Stopper part

Claims (3)

A power element that senses the temperature and pressure of the refrigerant introduced from the evaporator, and a valve unit that controls the flow rate of the refrigerant supplied to the evaporator according to the temperature and pressure of the refrigerant, the power element sandwiching the diaphragm In the expansion valve constructed by welding the outer peripheral edge portions of the first housing and the second housing arranged on both sides thereof together with the diaphragm,
The first housing that constitutes the temperature sensing chamber together with the diaphragm constitutes a stopper portion whose outer peripheral portion regulates the amount of overstroke of the diaphragm, and the diaphragm has a central pressure receiving portion when the valve portion is fully closed. An expansion valve that is set to be positioned in the vicinity of a plane including a welded portion of the diaphragm.   The expansion valve according to claim 1, wherein the stopper portion is formed so as to be close to the plane including the welded portion of the diaphragm. The expansion valve according to claim 2, wherein the stopper portion is formed in a region corresponding to an outer periphery of the diaphragm to an inner side of the corrugated portion.

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