JP2009030888A - Flow control expansion valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow control expansion valve closable when air conditioning control on the rear side is not performed and more inexpensive than a solenoid valve integrated type temperature expansion valve. <P>SOLUTION: A valve element 29 arranged on the downstream side of a valve seat 28 and a cylindrical pressure receiving member 33 having an effective pressure receiving area approximately equal to that of the valve element 29 are jointed to each other by a valve shaft 32, and high pressure supplied to a high-pressure refrigerant inlet 37 is canceled by the valve element 29 and the cylindrical pressure receiving member 33. The valve element 29 is energized in the valve closing direction by a spring 30 and is made receive an evaporator inlet pressure Px in the valve closing direction, and the pressure receiving member 33 is made receive the evaporator outlet pressure Pe in the valve opening direction. Due to this configuration, when current is not carried in a solenoid 42, the valve element 29 is seated on the valve seat 28 by the spring 30 and closed, and when current is carried, control is performed to make a pressure difference (Px-Pe) constant by valve lift set by the solenoid 42. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flow control expansion valve, and more particularly to a flow control expansion valve suitable for use as an expansion valve in a rear circuit of an automotive air conditioner capable of independently air-conditioning a front side and a rear side in a vehicle interior.

  2. Description of the Related Art Conventionally, there has been known an automobile air conditioner that can independently air-condition a front side and a rear side of a vehicle interior. In such an automobile air conditioner, a front expansion valve and an evaporator circuit for controlling the air conditioning on the front side and a rear expansion valve and an evaporator circuit for performing the air conditioning control on the rear side are arranged in parallel. A refrigeration cycle configured as described above is used. Here, as expansion valves used in the front side circuit and the rear side circuit, the temperature and pressure of the refrigerant at the outlet of each evaporator are sensed and evaporated so that the refrigerant at the outlet of the evaporator has a predetermined superheat degree. In many cases, a temperature-type expansion valve that controls the flow rate of the refrigerant supplied to the vessel is used.

In such an automobile air conditioner, there is a case where the air conditioning control is performed only on the front side without performing the rear side air conditioning control depending on the passenger's boarding situation or the like. When the rear-side air conditioning control is not performed, the refrigerant is prevented from flowing into the rear-side circuit. This is a temperature-type expansion valve that senses the temperature of the refrigerant at the outlet of the evaporator when rear-side air conditioning control is being performed. Since the refrigerant may enter the valve state, the refrigerant flows through the expansion valve and the evaporator, and a flow noise is generated by the flow, or the refrigerant accumulates in the evaporator and is necessary for air conditioning control on the front side. This is because the refrigerant may run out. For this purpose, an electromagnetic valve is installed in the rear circuit, or an electromagnetic valve-integrated expansion valve (see, for example, Patent Document 1) in which a solenoid valve is integrated with a temperature-type expansion valve is used. When the air conditioning on the side is stopped, the rear circuit is closed so that the refrigerant does not pass through the expansion valve, and the refrigerant does not flow into the rear evaporator.
Japanese Patent Laid-Open No. 10-73345 (FIG. 2)

  However, the solenoid valve or the solenoid valve-integrated expansion valve installed for opening and closing the rear-side refrigerant flow path is expensive and raises the problem of increasing the cost of the automotive air conditioner.

  The present invention has been made in view of the above points, and can be closed when the rear side air-conditioning control is not performed, and is less expensive than the temperature type expansion valve integrated with a solenoid valve. The purpose is to provide.

  In the present invention, in order to solve the above problem, in the flow control expansion valve that controls the flow rate of the refrigerant sent to the evaporator to be substantially constant, the refrigerant inlet pipe is arranged substantially coaxially inside the refrigerant outlet pipe to form a double pipe structure. The first inner tube and the first outer tube are connected to the evaporator, and the main cylindrical portion having one end formed in a substantially coaxial double tube structure and extending in a direction perpendicular to the main cylindrical portion. The body having the pipe connection part taken out and the second outer pipe having a double pipe structure formed so as to communicate with the first outer pipe on the other end side of the main columnar part are hermetically closed. In the space formed in the axial direction between the solenoid coupled to the main cylindrical part and the first inner pipe on one end side of the main cylindrical part and the second inner pipe on the other end side of the pipe connecting part The passage between the high pressure inlet and the first inner pipe of the main cylindrical part is opened and closed. The valve is closed when the solenoid is de-energized, and when energized, the valve is lifted according to the magnitude of the energization current, the evaporator inlet pressure in the first inner pipe, and the evaporator outlet in the second outer pipe By sensing a differential pressure with respect to the pressure, and causing the valve portion that is opened when the solenoid is energized to act in a valve closing direction against a change in the direction in which the differential pressure increases, the first inner pipe removes the pressure from the first inner pipe. There is provided a flow rate control expansion valve comprising a differential pressure sensing unit that controls the flow rate of the refrigerant sent to the evaporator to be substantially constant.

  According to such a flow control expansion valve, the flow rate of the refrigerant sent to the evaporator is controlled to be substantially constant by sensing the differential pressure before and after the evaporator and controlling the differential pressure so that the differential pressure becomes constant. The flow rate of the refrigerant to be controlled at a constant level can be set by the energizing current that is passed through the solenoid. By comprising the valve part and the solenoid by the differential pressure control, the construction can be simplified and an inexpensive expansion valve can be provided.

  The flow control expansion valve of the present invention includes a valve unit that senses a differential pressure between the evaporator inlet pressure and the evaporator outlet pressure and controls the pressure difference to be constant, and a solenoid that sets the differential pressure from the outside. Because it is a constant differential pressure control valve configured by the above, the overall configuration is simplified, and furthermore, because no power element with high cost is used, which encloses gas having the same or similar characteristics as the refrigerant, it is significantly lower There is an advantage that the cost can be increased.

  Hereinafter, referring to the drawings, the embodiment of the present invention is applied to an expansion valve for rear side air conditioning of a refrigeration cycle having an internal heat exchanger in order to improve the efficiency of an automotive air conditioner. This will be described in detail.

FIG. 1 is a system diagram showing a refrigeration cycle of an automotive air conditioner.
This refrigeration cycle is arranged in an engine room of a vehicle, and compresses a refrigerant 1, a condenser 2 that cools and condenses the compressed refrigerant, and separates the condensed refrigerant into gas and liquid. And a receiver 3 for sending out liquid refrigerant. A front-side expansion valve 4 that squeezes and expands the liquid refrigerant and a front-side evaporator 5 that evaporates the expanded refrigerant are arranged on the front side of the vehicle interior, and the liquid refrigerant is throttled on the rear side of the vehicle interior. A flow control expansion valve 6 for expansion and a rear evaporator 7 for evaporating the expanded refrigerant are arranged. The receiver 3 is connected to the front side expansion valve 4 and the flow rate control expansion valve 6 by an internal heat exchanger 8. Further, in the vicinity of the front-side evaporator 5 and the rear-side evaporator 7, blowers 9 and 10 are provided for allowing the air in the vehicle compartment to pass therethrough.

  The front side expansion valve 4 senses the temperature and pressure of the refrigerant at the outlet of the front side evaporator 5 and supplies the refrigerant to the front side evaporator 5 so that the refrigerant at the outlet of the front side evaporator 5 has a predetermined superheat degree. It is a temperature type expansion valve that controls the flow rate of the refrigerant. Of course, the front side expansion valve 4 may be an electronic expansion valve controlled based on various sensor values. Further, the flow control expansion valve 6 is closed when the power is not supplied when the operation is stopped, and the current is controlled by the control unit 11 during the operation. The control unit 11 is connected to a temperature sensor 12 and a blower 9 installed in the vicinity of the air inlet of the rear-side evaporator 7, and is estimated from the temperature and air volume of air applied to the rear-side evaporator 7 by the blower 9. The flow rate control expansion valve 6 is controlled based on the refrigeration load. Note that the calculation unit and the temperature sensor 12 for estimating the refrigeration load in the control unit 11 are actually part of a control device that controls the automotive air conditioner and are not newly installed. .

  Here, for example, when air conditioning is performed only on the front side, the flow control expansion valve 6 closes the refrigerant flow path of the rear side circuit, and the compressor 1 and the blower 9 are activated. The high-temperature and high-pressure refrigerant compressed by the compressor 1 is condensed by the condenser 2 and stored in the receiver 3. The liquid refrigerant in the receiver 3 is supplied to the front side expansion valve 4 through the internal heat exchanger 8, where it is throttled and expanded to become a low-temperature / low-pressure refrigerant. The refrigerant that has become a low-temperature and low-pressure refrigerant is sent to the front-side evaporator 5, where it is evaporated by heat exchange with the air in the vehicle compartment sent by the blower 9. The evaporated refrigerant is sent to the inlet of the compressor 1 through the front side expansion valve 4 and the internal heat exchanger 8.

  When the evaporated refrigerant passes through the front side expansion valve 4, the front side expansion valve 4 senses the temperature and pressure of the refrigerant in the front side evaporator 5, and the refrigerant at the outlet of the front side evaporator 5 has a predetermined value. The flow rate of the refrigerant sent to the front-side evaporator 5 is controlled so that the degree of superheat is reached. The internal heat exchanger 8 exchanges heat between the high-temperature refrigerant flowing from the receiver 3 toward the front side expansion valve 4 and the low-temperature refrigerant flowing from the front side expansion valve 4 toward the compressor 1. Thereby, the refrigerant sent to the front side expansion valve 4 is further cooled, and the refrigerant sent to the compressor 1 is further overheated, so that the enthalpy difference between the inlet of the front side expansion valve 4 and the inlet of the compressor 1 is increased. growing. As a result, since the coefficient of performance of the refrigeration cycle is improved, the load on the traveling engine that drives the compressor 1 can be reduced, and the efficiency of the automotive air conditioner can be improved.

  When rear-side air conditioning is performed, the flow control expansion valve 6 is energized and the blower 10 is activated. As a result, the high-temperature and high-pressure liquid refrigerant branched by the internal heat exchanger 8 is supplied to the flow control expansion valve 6, where it is throttled and expanded into a low-temperature and low-pressure refrigerant. The refrigerant that has become a low-temperature and low-pressure refrigerant is sent to the rear-side evaporator 7, where it is evaporated by heat exchange with the air in the vehicle compartment sent by the blower 10. The evaporated refrigerant is sent to the inlet of the compressor 1 through the flow control expansion valve 6 and the internal heat exchanger 8. When the evaporated refrigerant passes through the flow control expansion valve 6, the flow control expansion valve 6 senses the differential pressure across the rear evaporator 7, and the differential pressure corresponds to a predetermined differential pressure corresponding to the supplied current. The flow rate of the refrigerant sent to the rear evaporator 7 is controlled so as to maintain the above.

  Thus, in the front side expansion valve 4 on the front side, the flow rate of the refrigerant sent to the front side evaporator 5 is always accurately controlled so that the refrigerant discharged from the front side evaporator 5 has a predetermined superheat degree, While the liquid refrigerant that causes the failure of the compressor 1 never returns to the compressor 1, the flow control expansion valve 6 on the rear side does not perform accurate flow control like the front expansion valve 4. Not required. This is because the refrigeration cycle includes the internal heat exchanger 8. That is, even if the flow control expansion valve 6 performs rough flow control and the refrigerant on the wet side without being completely evaporated from the rear-side evaporator 7 is discharged, Before reaching the inlet of the compressor 1, it is completely evaporated by the internal heat exchanger 8 and further heated. Therefore, an inexpensive flow rate control expansion valve that has a simple configuration and can be closed when not energized without using an expensive temperature expansion valve or an expansion valve integrated with a solenoid valve. 6 can be used. Next, a specific example of such a flow control expansion valve 6 will be described.

FIG. 2 is a cross-sectional view showing a state when the flow control expansion valve according to the first embodiment is not energized, and FIG. 3 is a view showing characteristics of the flow control expansion valve according to the first embodiment.
The flow control expansion valve 21 according to the first embodiment corresponds to the flow control expansion valve 6 of FIG. 1 and has a configuration in which it is directly connected to the refrigerant inlet and the refrigerant outlet of the rear side evaporator 7. is doing. The rear-side evaporator 7 is configured by laminating a plurality of aluminum plates, and has a refrigerant inlet pipe 22 for introducing a refrigerant and a refrigerant outlet pipe 23 for leading out the refrigerant in a header portion thereof. The refrigerant outlet pipe 23 is disposed substantially coaxially with the refrigerant inlet pipe 22 so as to surround the refrigerant inlet pipe 22 and has a double pipe structure. The rear evaporator 7 is formed by simultaneously welding the stacked plates by brazing in the furnace. At this time, the refrigerant inlet pipe 22 and the refrigerant outlet pipe 23 are also welded together. Are integrally formed.

  The flow control expansion valve 21 includes a body 26 having an outer shape in which a main cylinder portion 24 extending in the left-right direction in FIG. 2 and a sub cylinder portion 25 extending in a downward direction in FIG. The sub-cylindrical part 25 constitutes a pipe connection part connected to the pipe of the internal heat exchanger 8. The main cylindrical portion 24 and the sub-cylindrical portion 25 have a double pipe structure in their end surfaces. The main cylindrical portion 24 has a central hole in the center thereof in which the movable portion of the expansion valve is accommodated in the axial direction, and a plurality of low-pressure refrigerant introduced from the rear-side evaporator 7 flows around the central hole. A passage is formed penetrating in the axial direction. Therefore, this body 26 is preferably formed by processing an extruded hollow material in which a central hole and a plurality of passages are formed in advance by hollow extrusion processing to form a double tube structure in three directions.

  In the middle of the central hole of the main cylindrical portion 24, a shaft guide 27 and a ring-shaped valve seat 28 are fixed to the body 26 by caulking. A valve element 29 is disposed so as to be able to contact and separate from the valve seat 28. The valve body 29 is urged in the valve closing direction by a spring 30, and the spring 30 is press-fitted into an inner pipe of a double pipe formed on the rear side evaporator 7 side of the main cylindrical portion 24. Received by 31. The load of the spring 30 is adjusted by the internal press-fitting amount of the spring receiving member 31 that is press-fitted into the inner pipe of the double pipe.

  The valve body 29 is formed integrally with a valve shaft 32 that extends in the axial direction via the valve seat 28 and the shaft guide 27. A cylindrical pressure receiving member 33 is fitted on the end of the valve shaft 32 opposite to the side on which the valve body 29 is formed, and the valve shaft 32 closer to the valve body 29 than the cylindrical pressure receiving member 33 is sealed. An O-ring 34 is provided around. The inner diameter of the inner tube of the double pipe, which is the central hole of the main cylindrical portion 24 that accommodates the cylindrical pressure receiving member 33, is approximately equal to the inner diameter of the valve hole of the valve seat 28. Since the effective pressure receiving area in which the high pressure receives the high pressure in the valve opening direction and the effective pressure receiving area in which the O-ring 34 receives the high pressure in the valve closing direction are approximately equal, the high pressure received by the valve body 29 in the valve opening direction is The O-ring 34 is canceled by the same pressure received in the valve closing direction.

  The inner pipe of the main cylindrical portion 24 formed in a double pipe structure on the side where the spring receiving member 31 is press-fitted constitutes a low-pressure refrigerant outlet 35 of the flow control expansion valve 21 and is formed on the outer periphery thereof. The annular groove constitutes a return low-pressure refrigerant inlet 36 that receives the refrigerant returned from the rear-side evaporator 7. Here, the low-pressure refrigerant outlet 35 of the flow control expansion valve 21 is fitted to the refrigerant inlet pipe 22 of the rear evaporator 7, and the fitting portion is sealed by an O-ring. Further, the return low-pressure refrigerant inlet 36 of the flow control expansion valve 21 is fitted into the refrigerant outlet pipe 23 of the rear evaporator 7 and mechanically coupled to the rear evaporator 7 by caulking the entire tip. The fitting portion with the refrigerant outlet pipe 23 is sealed with an O-ring.

  The installation space of the shaft guide 27 in the central hole of the main cylindrical part 24 is connected to the inner pipe of the double pipe structure formed in the sub-cylindrical part 25, and is parallel to the central hole around the central hole of the main cylindrical part 24. The passage formed in the communication with the space between the inner tube and the outer tube formed in the sub-cylindrical portion 25. Here, the inner tube of the sub-cylindrical portion 25 constitutes a high-pressure refrigerant inlet 37, and the space between the inner tube and the outer tube of the sub-cylindrical portion 25 is the refrigerant that has passed through the flow control expansion valve 21 as a compressor. The return low-pressure refrigerant outlet 38 is returned to the inlet 1. Therefore, the high-pressure refrigerant inlet 37 of the flow control expansion valve 21 is fitted with a high-pressure pipe 39 to which high-temperature and high-pressure liquid refrigerant from the receiver 3 is supplied and is sealed by an O-ring. Further, the return low-pressure refrigerant outlet 38 of the flow control expansion valve 21 is fitted into the return low-pressure pipe 40, and the return low-pressure pipe is formed by caulking the entire circumference so as to fix the backup ring 41 fitted in the tip. 40 and mechanically coupled with the return low-pressure pipe 40 is sealed by an O-ring. In this embodiment, the high-pressure pipe 39 and the return low-pressure pipe 40 connected to the sub-cylindrical portion 25 have a double pipe structure, which constitutes the internal heat exchanger 8 of FIG.

  As described above, the flow control expansion valve 21 is connected to the rear evaporator 7 as a coaxial double pipe structure by caulking of the entire circumference of the outer pipe. Since connections can be made simultaneously and the connection to the rear evaporator 7 is coaxial, the body 26 is connected to the low pressure refrigerant outlet 35 and the return low pressure refrigerant inlet 36 before joining to the rear evaporator 7. Therefore, the direction of the opening direction of the high pressure refrigerant inlet 37 and the return low pressure refrigerant outlet 38 into which the high pressure pipe 39 and the return low pressure pipe 40 are fitted can be freely changed.

  The opposite side of the main cylindrical portion 24 to the side connected to the rear evaporator 7 also has a double tube structure, and its open end is closed by a solenoid 42. The solenoid 42 has a core 43, and its flange portion is airtightly coupled to the main cylindrical portion 24 by caulking the outer tube of a double tube structure all around. The core 43 is fitted with an open end of a bottomed sleeve 44 extending in the same direction as the valve shaft 32, and a plunger 45 is disposed in the bottomed sleeve 44. The plunger 45 is fixed to a shaft 46 that penetrates the core 43 and extends in the same direction as the valve shaft 32. The shaft 46 is fixed to the bottom of the bearing portion 47 and the bottomed sleeve 44 that are press-fitted and fixed to the core 43. The formed bearing portion 48 is held so as to be movable back and forth in the axial direction. In the solenoid 42, a coil 49 is provided around the bottomed sleeve 44 and surrounded by a yoke 50. Therefore, in the flow control expansion valve 21, when the coil 49 is not energized, the valve body 29 is seated on the valve seat 28 by the urging force of the spring 30 and is closed. When the coil 49 is energized, the plunger 45 is attracted by the core 43 and the shaft 46 fixed to the plunger 45 against the biasing force of the spring 30 causes the valve shaft 32 integrated with the valve body 29 to open in the valve opening direction. Push to open. The lift of the valve body 29 is determined by the magnitude of the current supplied to the coil 49.

  In the flow control expansion valve 21 configured as described above, front side air conditioning is performed, but when the rear side air conditioning is stopped, power is not supplied to the coil 49 of the solenoid 42, as shown in FIG. The flow control expansion valve 21 is closed. That is, since the air conditioner for automobiles performs air conditioning on the front side, high-temperature and high-pressure liquid refrigerant is supplied from the receiver 3 through the high-pressure pipe 39 of the internal heat exchanger 8 to the high-pressure refrigerant inlet 37. Since the high pressure is canceled by making the inner diameter of the inner pipe of the double pipe of the main cylindrical portion 24 accommodating the cylindrical pressure receiving member 33 substantially equal to the inner diameter of the valve hole, the valve element 29 is It is seated on the valve seat 28 by the urging force of the spring 30 and is closed.

  Here, when the coil 49 of the solenoid 42 is energized to perform rear-side air conditioning, the valve element 29 is lifted according to the magnitude of the energized current, and the flow control expansion valve 21 is opened. As a result, when the high-temperature and high-pressure liquid refrigerant is supplied from the receiver 3 to the high-pressure refrigerant inlet 37 through the high-pressure pipe 39 of the internal heat exchanger 8, the liquid refrigerant is removed from the gap between the valve seat 28 and the valve element 29. Flows out to the low-pressure refrigerant outlet 35. At this time, the refrigerant is adiabatically expanded to become a low-temperature / low-pressure gas-liquid mixed refrigerant, and is introduced into the rear evaporator 7 through the refrigerant inlet pipe 22. In addition, the arrow in a figure has shown the flow direction of the refrigerant | coolant. In the rear side evaporator 7, the introduced refrigerant is evaporated by heat exchange with the air in the passenger compartment and flows out from the refrigerant outlet pipe 23. The refrigerant is introduced from the return low-pressure refrigerant inlet 36, flows out to the return low-pressure refrigerant outlet 38 through a plurality of low-pressure refrigerant passages, and is returned to the inlet of the compressor 1 through the return low-pressure pipe 40.

  Here, the expansion valve inlet pressure of the refrigerant supplied by the high-pressure pipe 39 is Po, the expansion valve outlet pressure (evaporator inlet pressure) of the refrigerant adiabatically expanded is Px, and the evaporator outlet returned from the rear-side evaporator 7. When the pressure is Pe, the evaporator inlet pressure Px is applied to the valve body 29 in the valve closing direction, and the evaporator shaft outlet pressure in the valve opening direction is applied to the valve shaft 32 and the tubular pressure receiving member 33 integral with the valve body 29. Pe is added. Therefore, since the differential assembly (Px-Pe) between the inlet pressure and the outlet pressure of the rear evaporator 7 is applied to the integral assembly of the valve body 29, the valve shaft 32, and the cylindrical pressure receiving member 33, The assembly constitutes a differential pressure sensing unit that senses the differential pressure (Px−Pe) with this flow control expansion valve 21.

  When the flow control expansion valve 21 supplies the refrigerant to the rear evaporator 7 with a predetermined valve lift set by the solenoid 42, the flow rate of the refrigerant passing through the rear evaporator 7 increases and the rear evaporation occurs. When the pressure loss in the vessel 7 increases, the differential pressure across the evaporator (Px−Pe) increases, so that the valve element 29 moves in the valve closing direction and acts to throttle the flow rate. On the contrary, when the flow rate of the refrigerant passing through the rear evaporator 7 decreases and the evaporator front-rear differential pressure (Px−Pe) decreases, the valve body 29 moves in the valve opening direction and acts to increase the flow rate. . Therefore, the flow control expansion valve 21 controls the pressure difference between the inlet and the outlet of the rear evaporator 7 to be constant, thereby controlling the flow rate of the refrigerant sent to the rear evaporator 7 to be substantially constant. Works. Further, since the differential pressure to be controlled to be constant is set by the solenoid 42, the flow control expansion valve 21 is substantially constant at the flow rate of the refrigerant passing through the rear side evaporator 7 to the flow rate set by the solenoid 42. It is also what controls. Therefore, as shown in FIG. 3, the flow control expansion valve 21 controls the evaporator front-rear differential pressure (Px−Pe), which is set according to the magnitude of the current supplied to the coil 49 of the solenoid 42, to be substantially constant. It has the characteristic to do. Moreover, the differential pressure across the evaporator (Px−Pe) is not affected at all by the magnitude of the expansion valve inlet pressure Po because the expansion valve inlet pressure Po is canceled by the back pressure.

  Note that the magnitude of the current supplied to the coil 49 of the solenoid 42 in order to control the flow control expansion valve 21 is set based on the estimated value of the refrigeration load on the rear side. The estimated value of the refrigeration load is obtained from the temperature and air volume of air applied to the rear evaporator 7 by the blower 9. The temperature of the air is detected by a temperature sensor 12 installed in the vicinity of the air inlet of the rear side evaporator 7, and the air volume is detected by the drive current or voltage of the blower 9 or by the air volume designation signal. The controller 11 calculates based on these data, estimates the refrigeration load, and supplies a current corresponding to the value to the coil 49 of the solenoid 42. As a result, the flow control expansion valve 21 controls the flow rate so as to supply the rear-side evaporator 7 with a refrigerant having a flow rate corresponding to the rear-side refrigeration load.

  FIG. 4 is a sectional view showing a state when the flow control expansion valve according to the second embodiment is not energized. In FIG. 4, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Compared with the flow control expansion valve 21 according to the first embodiment, the flow control expansion valve 61 according to the second embodiment is a differential pressure sensor that detects the differential pressure (Px−Pe) before and after the evaporator. It has been changed to increase the sensitivity of the part. That is, in the flow control expansion valve 61, a diaphragm 62 is airtightly attached to an inner pipe on the side where the solenoid 42 is attached to an outer pipe having a double pipe structure so as to close the inner pipe. The diaphragm 62 has an effective pressure receiving diameter sufficiently larger than the effective pressure receiving diameter of the valve body 29, and is fixed to the valve shaft 32 penetrating the center portion thereof. This fixing is performed by fitting the fixing members 63 and 64 to the valve shaft 32 so as to sandwich the central portion of the diaphragm 62. A pressure equalizing hole 65 is formed in the body 26 so that the evaporator inlet pressure Px is introduced to the side of the diaphragm 62 opposite to the side receiving the evaporator outlet pressure Pe. Further, the inner diameter of the central hole of the body 26 that accommodates the fixing member 63 is made substantially equal to the inner diameter of the valve hole of the valve seat 28 to cancel the expansion valve inlet pressure Po. Therefore, the flow control expansion valve 61 has the same characteristics as those shown in FIG.

  According to this flow control expansion valve 61, the evaporator outlet pressure Pe is applied in the valve opening direction to the surface on the solenoid 42 side of the diaphragm 62, and the evaporator inlet pressure in the valve closing direction is applied to the surface on the opposite side. Pressure Px is applied. Thus, even if it is the rear side evaporator 7 with a small pressure loss by enlarging a differential pressure sensing part, a differential pressure sensing part captures the evaporator back-and-front differential pressure (Px-Pe) reliably, and flow volume. Can be controlled.

  FIG. 5 is a cross-sectional view showing a state when the flow control expansion valve according to the third embodiment is not energized, and FIG. 6 is a view showing characteristics of the flow control expansion valve according to the third embodiment. In FIG. 5, the same components as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The flow control expansion valve 71 according to the third embodiment is configured such that the flow control expansion valves 21 and 61 according to the first and second embodiments cancel the expansion valve inlet pressure Po. The expansion valve inlet pressure Po is easy to open as the pressure increases. That is, this flow control expansion valve 71 has almost the same configuration as the flow control expansion valve 61 according to the second embodiment, but the effective pressure receiving area for receiving the expansion valve inlet pressure Po in the valve closing direction is opened. The effective pressure receiving area received in the valve direction is smaller.

  That is, a cylindrical stopper member 72 is fitted in the central hole of the body 26 so that the O-ring 34 does not fall off. Thus, the effective pressure receiving area that receives the expansion valve inlet pressure Po in the valve closing direction is equal to the cross-sectional area of the valve shaft 32 and is smaller than the effective pressure receiving area that the valve body 29 receives in the valve opening direction. Accordingly, as shown in FIG. 6, the flow control expansion valve 71 is set so that the valve opening characteristic of the evaporator front-rear differential pressure (Px−Pe) increases as the expansion valve inlet pressure Po increases. Of course, the inclination of the characteristic can be changed by changing the ratio between the effective pressure receiving area of the valve element 29 and the cross-sectional area of the valve shaft 32.

  FIG. 7 is a cross-sectional view showing a state when the flow control expansion valve according to the fourth embodiment is not energized, and FIG. 8 is a view showing characteristics of the flow control expansion valve according to the fourth embodiment. In FIG. 7, the same components as those shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The flow control expansion valve 81 according to the fourth embodiment has a valve opening characteristic opposite to that of the flow control expansion valve 71 according to the third embodiment. That is, in the flow control expansion valve 81, the valve body 29 is disposed on the upstream side of the valve seat 28, and the valve body 29 is always subjected to the expansion valve inlet pressure Po in the valve closing direction. The guide 82 is fixed to the valve shaft 32 while sandwiching the diaphragm 62 together with the fixing member 64, and guides the valve shaft 32 so as to advance and retreat in the axial direction. Therefore, the guide 82 is slidably disposed on the inner tube having a double tube structure in the body 26 on the solenoid 42 side, and further, a notch portion is provided in a part of the circumferential portion thereof. Thus, the evaporator inlet pressure Px on the downstream side of the valve seat 28 is correctly transmitted to the diaphragm 62 through the notch. In addition, the valve body 29 holds a flexible annular valve seat 83 on the opposite surface of the valve seat 28 to improve the airtightness when the valve is closed.

  According to this flow control expansion valve 81, when the solenoid 42 is in a non-energized state, the valve element 29 is urged by the spring 30 in the direction of seating on the valve seat 28, and the valve seat 28 is also driven by the expansion valve inlet pressure Po. Therefore, the flow control expansion valve 81 is held in a fully closed state.

  When the solenoid 42 is energized, the valve element 29 is lifted in accordance with the magnitude of the energization current to the solenoid 42. Here, the differential pressure sensing unit using the diaphragm 62 first receives the evaporator inlet pressure Px in the valve closing direction and the evaporator outlet pressure Pe in the valve opening direction, and the differential pressure (Px−Pe) is obtained. The valve element 29 is controlled so as to be substantially constant. Further, the differential pressure sensing unit is configured to move integrally with the valve body 29, and the valve body 29 is biased in the valve closing direction by the expansion valve inlet pressure Po. As shown in FIG. 8, the valve 81 has a characteristic that is set such that the opening characteristic of the evaporator differential pressure (Px−Pe) decreases as the expansion valve inlet pressure Po increases. become.

It is a system diagram which shows the refrigerating cycle of the air conditioner for motor vehicles. It is sectional drawing which shows the state at the time of the deenergization of the flow control expansion valve which concerns on 1st Embodiment. It is a figure which shows the characteristic of the flow control expansion valve which concerns on 1st Embodiment. It is sectional drawing which shows the state at the time of the deenergization of the flow control expansion valve which concerns on 2nd Embodiment. It is sectional drawing which shows the state at the time of the deenergization of the flow control expansion valve which concerns on 3rd Embodiment. It is a figure which shows the characteristic of the flow control expansion valve which concerns on 3rd Embodiment. It is sectional drawing which shows the state at the time of the deenergization of the flow control expansion valve which concerns on 4th Embodiment. It is a figure which shows the characteristic of the flow control expansion valve which concerns on 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Receiver 4 Front side expansion valve 5 Front side evaporator 6 Flow control expansion valve 7 Rear side evaporator 8 Internal heat exchanger 9 Blower 10 Blower 11 Control part 12 Temperature sensor 21 Flow control expansion valve 22 Refrigerant Inlet piping 23 Refrigerant outlet piping 24 Main cylindrical portion 25 Sub-cylindrical portion 26 Body 27 Shaft guide 28 Valve seat 29 Valve body 30 Spring 31 Spring receiving member 32 Valve shaft 33 Cylindrical pressure receiving member 34 O-ring 35 Low pressure refrigerant outlet 36 Return low pressure refrigerant Inlet 37 High-pressure refrigerant inlet 38 Return low-pressure refrigerant outlet 39 High-pressure pipe 40 Return low-pressure pipe 41 Backup ring 42 Solenoid 43 Core 44 Bottomed sleeve 45 Plunger 46 Shaft 47, 48 Bearing section 49 Coil 50 Yoke 61 Flow control expansion valve 62 Diaphragm 63, 64 Fixing member 6 5 Pressure equalizing hole 71 Flow control expansion valve 72 Stopper member 81 Flow control expansion valve 82 Guide 83 Valve seat

Claims (6)

In the flow control expansion valve that controls the flow rate of the refrigerant sent to the evaporator substantially constant,
The first inner pipe and the first outer pipe have a substantially coaxially arranged double pipe structure so that the refrigerant inlet pipe is connected substantially coaxially inside the refrigerant outlet pipe to the evaporator having the double pipe structure. A body having a main cylindrical portion having one end formed and a pipe connecting portion extending in a direction perpendicular to the main cylindrical portion;
A solenoid coupled to the main cylindrical portion so as to hermetically close a second outer tube having a double tube structure formed to communicate with the first outer tube on the other end side of the main cylindrical portion;
In the space formed in the axial direction between the first inner pipe on one end side of the main cylindrical part and the second inner pipe on the other end side, the high-pressure inlet of the pipe connecting part and the first of the main cylindrical part A valve portion that is accommodated so as to open and close a passage between the inner pipe, the valve is closed when the solenoid is not energized, and that is energized when energized;
The differential pressure between the evaporator inlet pressure in the first inner pipe and the evaporator outlet pressure in the second outer pipe is sensed, and the valve section opened when the solenoid is energized increases the differential pressure. A differential pressure sensing unit that controls the flow rate of the refrigerant sent from the first inner pipe to the evaporator to be substantially constant by acting in the valve closing direction against the change of
A flow control expansion valve comprising:   The body is formed in a double-pipe structure in which a third inner pipe in which the pipe connecting portion serves as the high-pressure inlet and a third outer pipe communicating with the first and second outer pipes are arranged in a substantially coaxial manner. 2. The flow control expansion valve according to claim 1, wherein the flow control expansion valve can be directly connected to an internal heat exchanger having a double-pipe structure for exchanging heat between the liquid refrigerant and the refrigerant returning to the compressor.   The valve portion is provided with a valve body disposed on the downstream side of the valve seat, a valve shaft extending in an axial direction from the valve body through the valve seat, and the valve body of the valve shaft. A pressure receiving member which is provided at an end opposite to the side and has an effective pressure receiving area substantially equal to the effective pressure receiving area of the valve body and cancels the pressure of the high pressure inlet, and the valve body is attached in the valve closing direction. The valve body, receiving the evaporator inlet pressure in the valve closing direction with respect to the valve body, and receiving the evaporator outlet pressure in the valve opening direction with respect to the pressure receiving member. 2. The flow control expansion valve according to claim 1, wherein an assembly of the valve shaft and the pressure receiving member functions as the differential pressure sensing unit. The valve portion is provided with a valve body disposed on the downstream side of the valve seat, a valve shaft extending in an axial direction from the valve body through the valve seat, and the valve body of the valve shaft. A pressure receiving member provided on a side opposite to the side and having an effective pressure receiving area substantially equal to an effective pressure receiving area of the valve body and canceling the pressure of the high pressure inlet; and a spring for biasing the valve body in a valve closing direction And
The differential pressure sensing unit has a central portion fixed to the valve shaft, receives the evaporator inlet pressure on the surface on which the valve body is disposed, and is opposite to the side on which the valve body is disposed. The flow control expansion valve according to claim 1, further comprising a diaphragm for receiving the evaporator outlet pressure on a side surface. The valve portion is provided with a valve body disposed on the downstream side of the valve seat, a valve shaft extending in an axial direction from the valve body via the valve seat, and the valve body of the valve shaft. A pressure receiving member that is provided on the opposite side of the valve body and has an effective pressure receiving area that is smaller than the effective pressure receiving area of the valve body and that causes the pressure at the high pressure inlet to act more in the valve opening direction; and the valve body in the valve closing direction. A spring for biasing,
The differential pressure sensing unit has a central portion fixed to the valve shaft, receives the evaporator inlet pressure on the surface on which the valve body is disposed, and is opposite to the side on which the valve body is disposed. 2. The flow control expansion valve according to claim 1, further comprising a diaphragm for receiving the evaporator outlet pressure on a side surface. The valve section includes a valve body disposed on the upstream side of the valve seat, a valve shaft extending in an axial direction from the valve body via the valve seat, and a spring that biases the valve body in a valve closing direction. And
The differential pressure sensing unit has a central portion fixed to the valve shaft, receives the evaporator inlet pressure on the surface on which the valve body is disposed, and is opposite to the side on which the valve body is disposed. The flow control expansion valve according to claim 1, further comprising a diaphragm for receiving the evaporator outlet pressure on a side surface.

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