JP2008215797A - Expansion valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion valve, controlling the temperature of a refrigerant discharged from a compressor from being elevated too high when refrigerating load is high in a refrigerating cycle using an internal heat exchanger. <P>SOLUTION: This expansion valve includes a pressure sensitive actuator 13 for sensing a differential pressure between the pressure Px of a refrigerant delivered from the expansion valve 5 to an evaporator and the pressure Pe of the refrigerant returned from the evaporator and varying the load of a spring for adjusting a set value, wherein when the refrigerating load is very high and a large quantity of refrigerant is circulated, the actuator senses that the differential pressure before and after the evaporator becomes higher than a predetermined value, and the load of the spring 19 is reduced to raise the set value. The expansion valve 5 feeds a refrigerant containing much moisture into the evaporator, whereby the temperature of the refrigerant leaving the evaporator is lowered, and heat-exchanged by the internal heat exchanger to restrain the degree of superheat of refrigerant of heat-exchanged by the internal heat exchanger and sucked in the compressor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an expansion valve, and more particularly to an expansion valve that controls the flow rate of refrigerant sent to the evaporator in accordance with the temperature and pressure of the refrigerant that has left the evaporator in a refrigeration cycle of a vehicle air conditioner.

  In the air conditioner for automobiles, it has been proposed that the refrigerant used in the refrigeration cycle is switched from an alternative chlorofluorocarbon (HFC-134a) to a natural refrigerant (carbon dioxide) due to environmental problems related to global warming. In the refrigeration cycle using carbon dioxide as a refrigerant, the basic configuration of the system is the same, but in general, an internal heat exchanger is used to increase the efficiency of the system (for example, Patent Document 1). reference.).

  The internal heat exchanger performs heat exchange between the refrigerant flowing through the path from the gas cooler that cools the high-temperature and high-pressure refrigerant compressed by the compressor to the expansion valve and the refrigerant flowing through the path from the accumulator to the compressor. It is configured. As a result, the refrigerant that has exited the gas cooler is further cooled by the internal heat exchanger, thereby reducing the enthalpy of the refrigerant at the inlet of the expansion valve and the evaporator, and the refrigerant sucked from the accumulator is reduced by the internal heat exchanger. Furthermore, since the enthalpy of the refrigerant | coolant of the inlet of a compressor is raised by being overheated, the efficiency of a system, ie, a coefficient of performance, and a refrigerating capacity can be improved.

On the other hand, even in a refrigeration cycle using HFC-134a or a gas having the same or similar characteristics as a refrigerant, a system incorporating an internal heat exchanger is considered, and the efficiency of the system is improved. It is expected.
JP 2001-108308 A

  However, in a refrigeration cycle using HFC-134a as a refrigerant, a temperature type expansion valve is generally used as an expansion valve. This temperature expansion valve is controlled so that the refrigerant at the outlet of the evaporator has a predetermined degree of superheat. Therefore, in a refrigeration cycle in which an internal heat exchanger is provided so as to exchange heat between the refrigerant flowing through the path from the condenser to the expansion valve and the refrigerant flowing through the path from the evaporator to the compressor, the evaporator The refrigerant already having a predetermined superheat degree at the outlet is further heated by the internal heat exchanger before being sent to the compressor. Therefore, especially when the refrigeration cycle is operated with a high refrigeration load, the temperature of the refrigerant compressed by the compressor tends to be too high, and the lubricating oil of the compressor deteriorates at a high temperature. There was a problem.

  The present invention has been made in view of these points, and prevents the temperature of the refrigerant compressed by the compressor from becoming too high when the refrigeration load is high in the refrigeration cycle using the internal heat exchanger. An object of the present invention is to provide an expansion valve that can be used.

  In the present invention, in order to solve the above problem, in the expansion valve that senses the temperature and pressure of the refrigerant at the outlet of the evaporator and controls the flow rate of the refrigerant to be sent to the evaporator, the pressure of the refrigerant sent to the evaporator and the An expansion valve is provided that includes a pressure-sensitive actuator that changes a set value in accordance with a differential pressure with respect to the pressure of the refrigerant returned from the evaporator.

  According to such an expansion valve, when the refrigeration load is very high and a large amount of refrigerant circulates and the differential pressure across the evaporator becomes higher than a predetermined value, the pressure-sensitive actuator detects it and sets the set value. The refrigerant is changed so as to increase the humidity, and a refrigerant containing a lot of moisture is sent to the evaporator. As a result, the refrigerant exiting the evaporator is passed to the internal heat exchanger in a wet state without being completely evaporated, and is completely evaporated in the internal heat exchanger, and further appropriately heated and sucked into the compressor. Is done. The refrigerant sucked into the compressor is overheated not by the evaporator but by the internal heat exchanger, so that it does not become too hot, and the refrigerant discharged from the compressor becomes too hot. Can be prevented.

  In the expansion valve of the present invention, when the refrigerant flow rate is large, such as when the outside air temperature is high and the refrigeration load is very high, the pressure sensitive actuator senses the differential pressure across the evaporator and sets the set value. Since the configuration is changed so as to increase the temperature, the temperature of the refrigerant discharged from the compressor can be lowered as a result of the temperature of the refrigerant exiting the evaporator being lowered by feeding a refrigerant with a large amount of liquid into the evaporator. There is an advantage that thermal deterioration of the lubricating oil of the compressor circulating in the refrigeration cycle together with the refrigerant can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system diagram showing a refrigeration cycle of an automotive air conditioner.
The refrigeration cycle of this automotive air conditioner includes a compressor 1 that compresses a refrigerant, a condenser 2 that condenses the compressed refrigerant by heat exchange with outside air, and separates the condensed refrigerant into gas and liquid and a refrigeration cycle. Receiver 3 for storing excess refrigerant, an internal heat exchanger 4, a temperature type expansion valve 5 for expanding and expanding the liquid refrigerant separated into gas and liquid, and heat of the expanded refrigerant with the air in the passenger compartment And an evaporator 6 that evaporates by exchange. The expansion valve 5 is accommodated in the case 7, in which the refrigerant inlet is connected to the outlet pipe of the high-pressure passage 4 a of the internal heat exchanger 4, and the refrigerant outlet is connected to the inlet pipe of the evaporator 6. . In the case 7, the outlet pipe of the evaporator 6 and the inlet pipe of the low pressure passage 4 b of the internal heat exchanger 4 are opened inside.

  The internal heat exchanger 4 has a high-pressure passage 4a for flowing a high-temperature and high-pressure refrigerant to the expansion valve 5 and a low-pressure passage 4b for flowing a low-temperature and low-pressure refrigerant to the compressor 1, and the high-temperature and high-pressure flowing through the high-pressure passage 4a. Heat exchange is performed between the refrigerant and the low-temperature and low-pressure refrigerant flowing through the low-pressure passage 4b. As a result, the refrigerant in the high-pressure passage 4a is supercooled by the refrigerant in the low-pressure passage 4b, and the refrigerant in the low-pressure passage 4b is superheated by the refrigerant in the high-pressure passage 4a, thereby improving the efficiency of the refrigeration cycle. it can.

  Here, the expansion valve 5 according to the present invention operates to sense the differential pressure between the refrigerant inlet and the refrigerant outlet of the evaporator 6 to vary the set value which is the superheat degree set value, and flows through the evaporator 6. When the flow rate of the refrigerant increases and the pressure loss in the evaporator 6 increases, the set value is changed. Therefore, when the refrigeration load increases and the flow rate of the refrigerant circulating in the refrigeration cycle increases and the pressure loss of the evaporator 6 exceeds a predetermined value, the expansion valve 5 is changed to increase the set value. As a result, the expansion valve 5 is more easily opened, so that the flow rate of the refrigerant expanding and expanding is increased, and the wet refrigerant is supplied to the evaporator 6. As a result, in the evaporator 6, the supplied refrigerant does not completely evaporate and comes out in a state containing the wet refrigerant, which passes through the internal heat exchanger 4 and becomes the compressor 1. Will flow to. In the internal heat exchanger 4, the refrigerant containing the wet refrigerant is completely evaporated, and further, heat exchange is performed so as to have an appropriate degree of superheat, so that the temperature of the refrigerant returned to the compressor 1 becomes high. Since the compressed refrigerant does not become too high, of course, the deterioration of the lubricating oil of the compressor 1 is prevented.

  2 is a cross-sectional view showing the expansion valve according to the first embodiment, FIG. 3 is an enlarged cross-sectional view taken along the line aa of FIG. 2 showing the details of the valve body of the expansion valve, and FIG. The figure which shows a pressure characteristic, FIG. 5 is the Mollier diagram for operation | movement explanation by the difference in refrigeration load. In the figure, the arrows indicate the flow direction of the refrigerant.

  The expansion valve 5 squeezes and expands the high-temperature / high-pressure liquid refrigerant to form a low-temperature / low-pressure refrigerant, and senses the temperature and pressure of the refrigerant exiting the evaporator 6 to detect the refrigerant in the valve unit 11. A power element 12 that controls the flow rate and a pressure-sensitive actuator 13 that changes the set value by sensing the pressure difference between the refrigerant inlet and the refrigerant outlet of the evaporator 6 are provided.

  The valve part 11 has an inlet port 15 into which a high-temperature and high-pressure liquid refrigerant is introduced from the receiver 3 on the side part of the body 14, and sends the expanded refrigerant to the evaporator 6 on the opposite side part. It has an outlet port 16. A passage in which the inlet port 15 and the outlet port 16 communicate with each other is formed in the body 14, and a valve seat 17 is formed in the middle of the passage.

  On the downstream side of the valve seat 17, a valve body 18 that can freely contact and separate from the valve seat 17 is disposed. The valve body 18 is arranged in a state of being biased in the valve closing direction by a spring 19 for adjusting the set value. The valve body 18 is also fixed to the shaft 20. The shaft 20 has a large-diameter portion 20a supported by the body 14 so as to be able to advance and retreat in the opening and closing direction of the valve body 18, and a small-diameter portion 20b extending through the valve hole of the valve seat 17. A valve body 18 is fixed to 20b. The large diameter portion 20a of the shaft 20 has the same outer diameter as the inner diameter of the valve hole, and the valve body 18 receives the high pressure introduced into the inlet port 15 in the valve opening direction, whereas the valve closing direction. The same high pressure is received and the high pressure is canceled. Further, a groove is provided in the large-diameter portion 20a of the shaft 20, and an O-ring 21 is fitted in the groove, so that the high-pressure refrigerant introduced into the inlet port 15 is the large-diameter portion of the body 14 and the shaft 20. Leakage into the power element 12 is prevented through a clearance with the air gap 20a. The valve body 18 fixed to the small-diameter portion 20b of the shaft 20 is integrally formed with a guide 18a that guides the valve body 18 so as to be in contact with and away from the valve seat 17. The guide 18a extends from the central portion of the valve seat 17 through the valve hole. As shown in detail in FIG. 3, the guide 18a has three protrusions that slide on the inner wall of the valve hole. And the space between the protrusions constitutes a passage through which the high-pressure refrigerant passes.

  The power element 12 screwed to the upper part of the figure of the body 14 is configured by arranging an upper housing 23 and a lower housing 24 on both sides of the diaphragm 22 and welding these outer peripheral edges to each other. Yes. A room surrounded by the diaphragm 22 and the upper housing 23 is filled with a gas mainly composed of a gas having characteristics similar to those of the refrigerant in the refrigeration cycle, and constitutes a greenhouse. The lower housing 24 has a central opening screwed into the body 14 and has at least one communication hole 25 formed therein. A disk 26 that transmits the displacement of the diaphragm 22 to the shaft 20 is disposed in the lower housing 24.

  Here, the temperature-pressure characteristics of the power element 12 in the temperature-sensitive room will be described with reference to FIG. In this figure, the horizontal axis represents the greenhouse temperature, the vertical axis represents the greenhouse pressure, the thin solid line R represents the saturation characteristics of the refrigerant gas used in the refrigeration cycle, and the thin dashed line A0 represents the greenhouse temperature. FIG. 3 shows the saturation characteristics of the gas filled in the valve, and shows the opening characteristics of a conventional expansion valve. A thick solid line A shown in FIG. 4 indicates the valve opening characteristic of the expansion valve 5, and the valve opening characteristic is moved by the pressure difference between the inlet and the outlet of the evaporator 6.

  A pressure sensitive actuator 13 is screwed to the lower portion of the body 14 in the figure. The pressure-sensitive actuator 13 is configured such that an upper housing 28 and a lower housing 29 are disposed on both sides of a diaphragm 27 and these outer peripheral edge portions are clamped together by a fixing member 30. Center disks 31 and 32 are arranged on both surfaces of the diaphragm 27, and are fixed by spring receiving members 33 arranged through the central portions thereof. The center disks 31, 32 are erected on the side away from the diaphragm 27, so that the diaphragm 27 contacts the upper housing 28 or the lower housing 29 when the diaphragm 27 is displaced by a predetermined amount. Displacement is regulated. The center disk 32 opposite to the valve portion 11 is urged in the valve closing direction by urging means comprising a spring 34. The spring 34 is received by a spring receiving member 35, and the spring load is adjusted by the screwing amount of the spring receiving member 35 into the lower housing 29. The spring load of the spring 19 urging the valve body 18 in the valve closing direction is adjusted by the screwing amount when the upper housing 28 is screwed to the body 14. The screwed portion between the upper housing 28 and the body 14 is sealed with an O-ring 36.

  In the expansion valve 5 configured as described above, the pressure sensitive actuator 13 is configured such that the diaphragm 27 is urged in the valve closing direction by the spring 34 so that the center disk 31 contacts the inner wall of the upper housing 28, and the refrigerant outlet of the expansion valve 5 is The load of the spring 34 is adjusted so that the diaphragm 27 is displaced in the valve opening direction when the pressure becomes larger than the pressure at the refrigerant outlet of the evaporator 6 by a predetermined value. The set value is adjusted by the pressure sensitive actuator 13.

  Here, when the automotive air conditioner is stopped, the gas enclosed in the temperature-sensitive room of the power element 12 of the expansion valve 5 is condensed and the pressure is lowered. Therefore, as shown in FIG. 22 is displaced toward the temperature-sensitive room, and the displacement is transmitted to the valve body 18 via the disk 26 and the shaft 20. The valve body 18 is seated on the valve seat 17 by the spring 19, and the expansion valve 5 is fully Closed.

  Here, when the automotive air conditioner is activated, the refrigerant in the case 7 which is the refrigerant outlet of the evaporator 6 is sucked by the compressor 1, so that the pressure Pe at the refrigerant outlet of the evaporator 6 decreases, which is the power. Detected by the element 12, the diaphragm 22 is displaced toward the valve portion 11, and the valve body 18 is lifted through the shaft 20. On the other hand, the refrigerant compressed by the compressor 1 is condensed by the condenser 2, and the liquid refrigerant separated by the receiver 3 is supplied to the inlet port 15 of the expansion valve 5 through the high-pressure passage 4 a of the internal heat exchanger 4. Is done.

  The high-temperature and high-pressure liquid refrigerant supplied to the inlet port 15 is squeezed and expanded as it passes through the expansion valve 5 and exits the outlet port 16 as a low-temperature and low-pressure gas-liquid mixed refrigerant. The refrigerant is sent to the evaporator 6, evaporated inside, and comes out from the refrigerant outlet. Here, the pressure of the refrigerant sent into the evaporator 6 is a pressure Px, and the pressure of the refrigerant returning from the evaporator 6 and entering the case 7 is a pressure Pe. The refrigerant in the case 7 returns to the compressor 1 through the internal heat exchanger 4 and the low pressure pipe.

  Since the space surrounded by the diaphragm 22 and the lower housing 24 of the power element 12 communicates with the inside of the case 7 through the communication hole 25, the refrigerant returned from the evaporator 6 passes through the case 7. The refrigerant is introduced and the temperature is sensed by the power element 12. At the initial stage of starting the air conditioner for automobiles, the temperature of the refrigerant returning from the evaporator 6 is high due to heat exchange with hot air in the passenger compartment, and the power element 12 senses the temperature and senses it. Greenhouse pressure is also high. Thereby, the diaphragm 22 is largely displaced toward the valve body 18, and the displacement is transmitted to the valve body 18 through the shaft 20, so that the expansion valve 5 is fully opened.

  Eventually, when the temperature of the refrigerant returning from the evaporator 6 decreases, the pressure in the sensation greenhouse decreases, so that the diaphragm 22 is displaced away from the valve body 18 accordingly, and the expansion valve 5 The flow rate of the refrigerant that operates in the valve closing direction and passes through the valve closing direction is controlled. At this time, the expansion valve 5 senses the temperature of the refrigerant exiting the evaporator 6 and controls the flow rate of the refrigerant supplied to the evaporator 6 so that the refrigerant maintains a predetermined degree of superheat. As a result, the overheated refrigerant always returns to the compressor 1, so that the compressor 1 can be operated efficiently.

  The above operation is the case where the refrigeration load is not so high and the flow rate of the refrigerant passing through the evaporator 6 is small. At this time, the pressure loss in the evaporator 6 is also small, so Since the differential pressure, that is, the differential pressure (Px−Pe) between the pressure Px and the pressure Pe does not increase so much, the pressure sensitive actuator 13 causes the center disk 31 to be moved by the spring 34 as shown in FIG. The position in contact with the inner wall of the upper housing 28 is maintained. Since this state is not different from the conventional expansion valve, the expansion valve 5 is operating as an ordinary temperature type expansion valve.

  On the other hand, when the automotive air conditioner is started with a high refrigeration load, such as when the outside air temperature is very high, the expansion valve 5 continues to flow a large flow of refrigerant. At this time, since the pressure loss when the refrigerant passes through the evaporator 6 increases, the differential pressure (Px−Pe) between the pressure Px at the outlet of the expansion valve 5 and the pressure Pe at the outlet of the evaporator 6 increases. When the pressure sensitive actuator 13 senses the differential pressure, the diaphragm 22 is displaced in the valve opening direction, and the center disk 32 comes into contact with the inner wall of the lower housing 29 against the urging force of the spring 34. Accordingly, the spring receiving member 33 is also moved in the valve opening direction, so that the load of the spring 19 is reduced, the set value is increased, and the valve portion 11 is set to be more easily opened. As a result, in the temperature-pressure characteristic shown in FIG. 4, the valve opening characteristic transitions from the point a to the point b when the set value of the expansion valve 5 increases. At the point b of the valve opening characteristic, the pressure in the temperature sensing chamber becomes higher than the pressure Pe of the refrigerant, so that the diaphragm 22 pushes down the shaft 20, and the expansion valve 5 remains open, A refrigerant containing a large amount is supplied to the evaporator 6. Therefore, the refrigerant comes out from the evaporator 6 without completely evaporating, and the refrigerant including the wet portion is evaporated by exchanging heat in the internal heat exchanger 4, and more appropriately. It is heated and sucked into the compressor 1. In this way, since the refrigerant sucked into the compressor 1 is controlled to have an appropriate degree of superheat, the temperature of the refrigerant compressed by the compressor 1 does not become too high, and the refrigeration cycle together with the refrigerant. Thermal deterioration of the lubricating oil of the compressor 1 circulating in the interior is eliminated.

  Here, refer to the Mollier diagram of FIG. 5 for the fact that the temperature of the refrigerant discharged from the compressor 1 does not become too high by changing the valve opening characteristics of the expansion valve 5 when the refrigeration load is high. To explain.

  The refrigeration cycle when the refrigeration load is not so high exhibits a behavior as shown by a thin solid line C1 in FIG. That is, the refrigerant exiting the evaporator 6 is heat-exchanged in the internal heat exchanger 4 and sucked into the compressor 1, but the superheat degree SH1 at that time is not so high, and is discharged from the compressor 1. The temperature of the refrigerant is also low.

  On the other hand, when the refrigeration load is very high, in the conventional expansion valve, as indicated by the one-dot chain line C2 in FIG. When the air is sucked into the machine 1, it is further heated by the internal heat exchanger 4, so the degree of superheat SH2 is very large. For this reason, the temperature of the refrigerant discharged from the compressor 1 is also high.

  On the other hand, the expansion valve 5 of the present invention is configured such that when the refrigeration load is very high, the valve opening characteristic is changed by the differential pressure before and after the evaporator 6 so that a refrigerant with a high liquid content is sent to the evaporator 6. As shown by the thick solid line C3 in FIG. 5, the state of the refrigerant at the outlet of the evaporator 6 is not completely evaporated but enters a saturated region between the saturated liquid line and the saturated vapor line. For this reason, even if the refrigerant exiting the evaporator 6 is heat-exchanged in the same manner in the internal heat exchanger 4, the resulting heat energy is used for evaporation of the moisture and moderate overheating. The refrigerant at the inlet of 1 only has a superheat degree SH3 smaller than the superheat degree SH2, and inevitably the temperature of the refrigerant discharged from the compressor 1 also becomes low. Thus, the expansion valve 5 of the present invention can reduce the degree of superheating when the refrigeration load is very high, and thus can prevent the discharge temperature from increasing.

  FIG. 6 is a sectional view showing an expansion valve according to the second embodiment. In FIG. 6, components having the same or equivalent functions as the components shown in FIG. 2 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion valve 5a according to the second embodiment changes the direction of the outlet port 16 and the configuration of the pressure-sensitive actuator 13 as compared with the expansion valve 5 according to the first embodiment. That is, the body 14 is extended in a cylindrical shape downward in the drawing so that the refrigerant expanded and squeezed out in the opening / closing direction of the valve body 18, and members constituting the pressure-sensitive actuator are disposed therein. Has been. In the body 14 extended in the cylindrical shape, a hollow piston 42 provided with a V packing 41 on its outer periphery is disposed so as to be able to advance and retract in the opening and closing direction of the valve body 18. A spring receiving member 33 is fixed by press fitting. The spring receiving member 33 receives the spring 19 for adjusting the set value, and the load of the spring 19 changes the position where the piston 42 is press-fitted into the piston 42 in a state where the piston 42 is in contact with the stepped portion 14 a of the body 14. Adjusted by.

  Three cylindrical members are disposed at the opening end of the body 14 in the lower part of the figure so as to surround the cylindrical spring receiving member 33. First, the cylindrical member 43 is fixed to the opening end of the body 14 by caulking, a spring receiving member 35 is press-fitted into the cylindrical member 43, and the outlet port 16 is configured at the opening end of the spring receiving member 35. The cylindrical member 44 to be fixed is fixed by caulking. A spring 34 is disposed between the piston 42 and the spring receiving member 35, and the load is adjusted by the position where the spring receiving member 35 is press-fitted into the tubular member 43. A V packing 45 is arranged inside the spring receiving member 35 so as to seal a gap between the spring receiving member 33 and the outer periphery thereof.

  Further, the body 14 and the cylindrical member 43 fixed thereby are provided with a communication hole 46, and the space in which the spring 34 is accommodated and the power element 12 has a refrigerant pressure Pe at the outlet of the evaporator 6. It communicates with the space where it senses. The cylindrical member 44 at the tip is provided with an O-ring 47 that performs sealing at a connection portion with the inlet of the evaporator 6.

  In the expansion valve 5a configured as described above, the piston 42 receives the pressure from the area A whose diameter is the inner diameter of the portion of the body 14 where the V-packing 41 is in sliding contact with the V-packing 45 of the spring receiving member 33. This is a value obtained by subtracting the area B whose diameter is the outer diameter of the portion. The pressure difference (Px−Pe) between the pressure Px introduced into the evaporator 6 and the pressure Pe derived from the evaporator 6 is applied to such a pressure receiving area (A−B). The same function as the pressure sensitive actuator 13 of the expansion valve 5 according to the first embodiment is configured.

  Therefore, when the pressure loss of the evaporator 6 caused by the flow of the refrigerant is small, the piston 42 is in contact with the stepped portion 14a of the body 14 by the spring 34, and the spring receiving member 33 does not move. 5a functions as a normal expansion valve. When the refrigerant flow rate is large and the differential pressure (Px−Pe) exceeds a predetermined value, such as when the refrigeration load is very high, the piston 42 opens the lower valve in the figure against the biasing force of the spring 34. Move in the direction. As a result, the spring receiving member 33 is also moved in the valve opening direction, so that the load of the spring 19 is reduced and the set value is increased. Therefore, the refrigerant derived from the expansion valve 5a has a larger liquid content. It is sent to the evaporator 6 in a state including Therefore, a refrigerant containing a wet portion in which the refrigerant has not completely evaporated comes out from the evaporator 6, and such a refrigerant is completely exchanged by the internal heat exchanger 4. After being evaporated, it is appropriately heated and sucked into the compressor 1. For this reason, the refrigerant sucked into the compressor 1 does not become too high in temperature, and the refrigerant compressed by the compressor 1 does not become too high in temperature. It is possible to prevent thermal deterioration of the lubricating oil of the compressor 1 that is present.

  7 is a cross-sectional view showing an application example of the expansion valve according to the second embodiment, FIG. 8 is a cross-sectional view taken along the line bb of FIG. 7, and FIG. 9 is an end view showing a connecting member of the internal heat exchanger, FIG. 10 is an end view showing the pipe joint.

  The evaporator 6 has a refrigerant inlet 51 for introducing a refrigerant and a refrigerant outlet 52 for deriving the refrigerant at one end face thereof. An inlet pipe 53 is joined to the refrigerant inlet 51, and a cylindrical connecting portion 54 is joined to the end face of the evaporator 6 so as to surround the refrigerant inlet 51 and the refrigerant outlet 52. Preferably, the inlet pipe 53 and the connecting portion 54 are welded together to the evaporator 6 when the evaporator 6 is formed by in-furnace brazing, and are integrally formed with the evaporator 6.

  A cylindrical case 7 whose one end is closed is airtightly joined to the connecting portion 54 via an O-ring 55, and the expansion valve 5 a is accommodated in the case 7. The expansion valve 5 a has an outlet port 16 connected to the inlet pipe 53 of the evaporator 6 and an inlet port 15 connected to a connection pipe 56 attached to the internal heat exchanger 4.

  The internal heat exchanger 4 is configured by a double pipe in which a low pressure passage 4b is concentrically arranged inside a high pressure passage 4a. One end of the double pipe is terminated by a connecting member 57, and the other end is terminated by a pipe joint 58.

  As shown in FIG. 9, the connecting member 57 is formed as an end face viewed from the case 7 side, and a passage 57 a having a U-shaped cross section is formed therethrough to constitute a low pressure introduction passage of the internal heat exchanger 4. In the center of the connecting member 57, a cylindrical portion 57b into which the connecting pipe 56 is fitted is formed. The central opening of the cylindrical portion 57b extends to substantially the center in the depth direction as seen in the cross-sectional views of FIGS. 7 and 8, and is formed so as to penetrate from the side to the inside. A high pressure lead-out path of the heat exchanger 4 is configured. The end face of the connecting member 57 on the back side from the high pressure lead-out path is formed in a cylindrical shape, and this is joined and joined to the low pressure passage 4b inside the double pipe. Also in the high-pressure passage 4a outside the double tube, the connection member 57 is joined on the tip side from the position where the high-pressure lead-out path opens. The connecting member 57 can be formed by cutting a drawing material through which a passage 57a having a U-shaped cross section is formed, into an appropriate length, and drilling and cutting it.

  The pipe joint 58 is concentrically disposed in the first connection hole 58a into which the high-pressure passage 4a is fitted, and the low-pressure passage 4b is fitted into the first connection hole 58a, on the end surface of the internal heat exchanger 4 side. And a second connection hole 58b. The high-pressure passage 4a fitted in the first connection hole 58a is pipe-engaged by caulking the outer peripheral portion of the first connection hole 58a inward and engaging with a rib formed near the tip of the high-pressure passage 4a. It is fixed to the joint 58.

  As shown in FIG. 10, the pipe joint 58 has a third connection hole 58c communicating with the first connection hole 58a and a fourth connection hole communicating with the second connection hole 58b on the end surface on the engine room side. These connection holes 58d are arranged in parallel. Further, screw holes 58e and 58f are formed adjacent to the third connection hole 58c and the fourth connection hole 58d. The screw hole 58e is for screwing a fixing plate provided near the tip of the high-pressure pipe after fitting the high-pressure pipe extending from the receiver 3 into the third connection hole 58c from the engine room side. The screw hole 58f is used for screwing a fixing plate provided near the tip of the low-pressure pipe after fitting the low-pressure pipe toward the refrigerant inlet of the compressor 1 from the engine room side to the fourth connection hole 58d. belongs to.

  Since the internal heat exchanger 4 must be connected to the side surface of the cylindrical case 7, a cylindrical connecting portion 59 is joined to the opening on the side surface of the case 7. Are connected by inserting the end of the low-pressure passage 4b closed by the connecting member 57. The connecting portion is sealed by an O-ring 60.

  As described above, the connection state between the expansion valve 5a accommodated in the case 7 and the high pressure passage 4a of the internal heat exchanger 4 and the connection state between the case 7 and the low pressure passage 4b of the internal heat exchanger 4 are as follows. Is maintained by. The clamp device 61 is formed so as to cover the first half of the side surface of the case 7 including the first locking member 61 a formed to cover the half of the side surface of the case 7 and the cylindrical connecting portion 59. It has the 2 locking member 61b and the fixing pin 61c which couple | bonds these 1st locking members 61a and the 2nd locking member 61b. The 1st locking member 61a and the 2nd locking member 61b have a restraining part which covers the fitting part of connecting part 54 and case 7 over the perimeter from the outside, and connecting part 54 and case 7 The movement in the fitting direction is restricted. The second locking member 61b has a locking portion that is locked to a rib formed in the vicinity of the tip of the low pressure passage 4b of the internal heat exchanger 4 in addition to the locking portion. When the locking member 61a and the second locking member 61b are coupled by the fixing pin 61c, the rib of the low-pressure passage 4b is locked so as not to come out of the connecting portion 59.

  In addition, about the internal heat exchanger 4, since it comprised with the double tube and made the outer side the high pressure channel | path 4a, since the high temperature refrigerant | coolant flows outside the internal heat exchanger 4, it is always high temperature. For this reason, dew condensation does not occur in the piping between the partition wall to which the pipe joint 58 is attached and the evaporator 6 between the vehicle compartment and the engine room, so that it is possible to eliminate the need for measures against dew condensation.

  FIG. 11 is a cross-sectional view showing an expansion valve according to the third embodiment, and FIG. 12 is a cross-sectional view showing an application example of the expansion valve according to the third embodiment. 11 and 12, components having the same or equivalent functions as those shown in FIGS. 6 and 7 are given the same reference numerals, and detailed descriptions thereof are omitted.

  In the expansion valves 5 and 5a according to the first and second embodiments, the spring 19 is used as a method of changing the load of the spring 19 for adjusting the set value according to the differential pressure before and after the evaporator 6. The receiving spring receiving member 33 is moved in the opening / closing direction of the valve body 18 in accordance with the differential pressure before and after the evaporator 6. On the other hand, in the expansion valve 5b according to the third embodiment, the spring receiving member 33 is fixed, and the valve element 18 and the power element 12 are placed on the valve body 18 according to the differential pressure before and after the evaporator 6. It differs in that it is moved in the opening and closing direction.

  The expansion valve 5b accommodates the valve portion 11 and the power element 12 in a valve case 71 so as to be movable back and forth in the opening / closing direction of the valve body 18. The valve case 71 has a stepped portion 71a that restricts the downward movement of the integral part of the valve part 11 and the power element 12 in the figure, and the top part of the valve case 71 has an upper limit position of the integral part. A prescribed cylindrical stopper 72 is fixed by press-fitting. A spring receiving member 35 is screwed into the hollow portion of the stopper 72, and the spring 34 is disposed between the spring receiving member 35 and the power element 12. The spring 19 for adjusting the set value is received by a spring receiving member 33 screwed into the valve case 71.

  The body 14 is provided with a high-pressure introduction groove 73 at a position where a high-pressure refrigerant is introduced, and seal grooves 74 and 75 are provided on both sides in the axial direction across the high-pressure introduction groove 73. V-packings 76 and 77 are installed in the sealing grooves 74 and 75.

  In the expansion valve 5b configured as described above, the pressure Px introduced into the evaporator 6 is received on the end face on the downstream side of the body 14, and the end face on which the power element 12 is screwed is led out from the evaporator 6. When the pressure Pe is received and the differential pressure (Px−Pe) increases, the body 14 moves so as to change the load of the spring 19 for adjusting the set value to be reduced. It has the same function as the pressure-sensitive actuator 13 of the expansion valve 5 according to the embodiment.

  When the differential pressure (Px−Pe) between the pressure Px and the pressure Pe is small, the body 14 is pushed downward by the spring 34 and is in contact with the stepped portion 71a. In this state, the expansion valve 5b functions as a normal expansion valve.

  On the other hand, when the refrigeration load is very high, the flow rate of the refrigerant is large, and the differential pressure (Px−Pe) exceeds a predetermined value, the body 14 moves away from the stepped portion 71 a against the urging force of the spring 34. As a result, the load on the spring 19 is reduced and the set value is changed in the increasing direction, so that the refrigerant derived from the expansion valve 5a is sent to the evaporator 6 in a state containing more liquid. Become. Therefore, a refrigerant containing a wet part comes out from the evaporator 6, and the refrigerant is completely evaporated by heat exchange in the internal heat exchanger 4, and further appropriately heated and compressed. The machine 1 is inhaled. For this reason, the refrigerant sucked into the compressor 1 does not become too high in temperature, and the refrigerant compressed by the compressor 1 does not become too high in temperature. It is possible to prevent thermal deterioration of the lubricating oil of the compressor 1 that is present.

  13 is a sectional view showing an expansion valve according to the fourth embodiment, FIG. 14 is a sectional view taken along the line cc of FIG. 13, and FIG. 15 shows an application example of the expansion valve according to the fourth embodiment. FIG. 16 is a cross-sectional view, and FIG. 16 is a diagram showing lift characteristics with respect to evaporator outlet pressure. 13 to 15, components having the same or equivalent functions as those shown in FIG. 12 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As a method of changing the set value according to the differential pressure before and after the evaporator 6, in the expansion valves 5, 5a, 5b according to the first to third embodiments, the valve body 18 is moved in the valve closing direction. The load of the spring 19 that was biased was changed in the direction of decreasing. In contrast, in the expansion valve 5c according to the fourth embodiment, the position of the valve seat 17 is shifted in the opening / closing direction of the valve body 18 in accordance with the differential pressure before and after the evaporator 6.

  The expansion valve 5c has a body 14 that also serves as the case 7 and the valve case 71 shown in FIG. The body 14 has an opening at the upper end of the figure which is closed when the power element 12 is fixed by caulking, and the lower end of the figure is a double tube in which the evaporator 6 is arranged concentrically. The outlet port 16 and the low-pressure introduction port 81 have a double pipe configuration so that the inlet pipe 53 and the connecting portion 54 of the configuration are directly connected, and the inlet port 15 into which the high-pressure refrigerant is introduced and the compression are provided on the side portions. A low pressure outlet port 82 for returning the low pressure refrigerant to the machine 1 is concentrically arranged.

  At the center of the body 14, there is provided a cylinder in which the pressure sensitive piston 83 is accommodated so as to be able to advance and retreat in the opening and closing direction of the valve body 18, and a step portion 14 a for restricting the downward movement of the pressure sensitive piston 83 in the drawing. Yes. The pressure sensitive piston 83 is urged so as to contact the stepped portion 14 a by a spring 84 disposed between the pressure sensitive piston 83 and the power element 12. Around the cylinder in which the pressure-sensitive piston 83 is accommodated, four low-pressure refrigerant passages 85 having a fan-shaped cross section are provided side by side as seen in the cross-sectional view of FIG. It communicates with the surroundings, and communicates with the space adjacent to the power element 12 at the upper end. 13 shows the body 14 in a section taken along the line dd in FIG. 14 and the pressure-sensitive piston 83 in a section taken along the line d-d 'in FIG.

  The pressure-sensitive piston 83 is provided with a high-pressure introduction groove 73 at a portion corresponding to the inlet port 15, and further has refrigerant introduction holes formed in four directions as shown in FIG. 14. Thus, the lower end portion of the pressure-sensitive piston 83 around which the V packing 76 is provided and the portion around which the V packing 77 is provided are connected by the four leg portions 83a. A shaft guide 86 and a ring-shaped valve seat 17 are provided in the lower end portion of the pressure-sensitive piston 83 around which the V packing 76 is provided by caulking.

  The shaft integral with the valve body 18 has a collar member 87 disposed at the end on the power element 12 side. The collar member 87 has an outer diameter substantially equal to the inner diameter of the valve seat 17, and the inlet port 15. The configuration is such that the high-pressure introduced in is canceled.

  A spring 19 that urges the valve body 18 in the valve closing direction and a spring receiving member 33 that receives the spring 19 are disposed in a cylinder coaxial with the outlet port 16 in which the valve body 18 is disposed. The spring receiving member 33 is press-fitted into the cylinder, and the set value of the spring 19 is adjusted by the amount of press-fitting.

  In the expansion valve 5c according to the fourth embodiment, the power element 12 is attached to the body 14 while being exposed to the atmosphere. Therefore, the fitting portion with the body 14 is sealed by the O-ring 88. ing.

  As shown in FIG. 15, the expansion valve 5 c configured as described above has the outlet port 16 of the body 14 fitted into the inlet pipe 53 of the evaporator 6, and the low-pressure introduction port 81 of the body 14 is connected to the evaporator 6. The portion 54 is fitted and joined by caulking. Similarly, the inlet port 15 of the body 14 is fitted into the high-pressure passage 4 a of the internal heat exchanger 4, and the low-pressure outlet port 82 of the body 14 is fitted into the low-pressure passage 4 b of the internal heat exchanger 4 for caulking. Are combined.

  In the expansion valve 5c configured as described above, the pressure-sensitive piston 83 that is disposed so as to be movable back and forth in the opening / closing direction of the valve body 18 and holds the valve seat 17 has an evaporator on the end surface on the side where the valve body 18 is disposed. 6 is received, and the pressure Pe derived from the evaporator 6 is received on the end surface on the side where the spring 84 is pressed. Therefore, when the differential pressure (Px−Pe) increases, the pressure sensitive piston 83 moves in the direction of the power element 12 against the biasing force of the spring 84, so that the valve seat 17 moves away from the valve body 18. Since the shift is performed, the expansion valve 5c is easily opened. For this reason, when the differential pressure (Px−Pe) increases, the pressure-sensitive piston 83 reduces the load of the spring 19 urging the valve body 18 in the valve closing direction so that the valve is easily opened. This has basically the same function as the pressure-sensitive actuator 13 of the expansion valve 5 according to the first embodiment in which the set value is increased.

  The change of the set value will be described with reference to the lift characteristics shown in FIG. 16. The curve illustrated here shows the lift characteristics when the temperature of the refrigerant that the power element 12 senses is 0 ° C., for example. Here, when the pressure difference (Px−Pe) between the pressure Px introduced into the evaporator 6 and the pressure Pe derived from the evaporator 6 is small, the pressure-sensitive piston 83 has a spring as shown in FIG. 84, the stroke range of the valve body 18 due to the change in the pressure Pe is L1, and the pressure Pe when starting the valve opening is the set value. Pset1. When the differential pressure (Px−Pe) increases and the pressure-sensitive piston 83 moves away from the stepped portion 14a against the urging force of the spring 84 as shown in FIG. 15, the valve seat 17 moves away from the valve body 18. Since it moves in the direction, the stroke range of the valve element 18 increases to L2, and the pressure Pe when starting the valve opening increases and moves to the set value Pset2.

  In this way, the expansion valve 5c has a very high refrigeration load, and when the refrigerant flow rate is large and the differential pressure (Px−Pe) exceeds a predetermined value determined by the load of the spring 84, the set value increases. Since it is changed, the refrigerant led out from the expansion valve 5c is sent to the evaporator 6 in a state containing more liquid. Therefore, a refrigerant containing a wet part comes out from the evaporator 6, and the refrigerant is completely evaporated by heat exchange in the internal heat exchanger 4, and further appropriately heated and compressed. The machine 1 is inhaled. For this reason, the refrigerant sucked into the compressor 1 does not become too high in temperature, and the refrigerant compressed by the compressor 1 does not become too high in temperature. It is possible to prevent thermal deterioration of the lubricating oil of the compressor 1 that is present.

It is a system diagram which shows the refrigerating cycle of the air conditioner for motor vehicles. It is sectional drawing which shows the expansion valve which concerns on 1st Embodiment. It is an aa arrow expanded sectional view of Drawing 2 showing details of a valve element of an expansion valve. It is a figure which shows the temperature-pressure characteristic of a sensitive room. It is a Mollier diagram for explanation of operation by the difference in refrigeration load. It is sectional drawing which shows the expansion valve which concerns on 2nd Embodiment. It is sectional drawing which shows the application example of the expansion valve which concerns on 2nd Embodiment. It is bb arrow sectional drawing of FIG. It is an end view which shows the connection member of an internal heat exchanger. It is an end view which shows a pipe joint. It is sectional drawing which shows the expansion valve which concerns on 3rd Embodiment. It is sectional drawing which shows the application example of the expansion valve which concerns on 3rd Embodiment. It is sectional drawing which shows the expansion valve which concerns on 4th Embodiment. It is cc arrow sectional drawing of FIG. It is sectional drawing which shows the application example of the expansion valve which concerns on 4th Embodiment. It is a figure which shows the lift characteristic with respect to evaporator outlet pressure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Receiver 4 Internal heat exchanger 4a High pressure passage 4b Low pressure passage 5, 5a, 5b Expansion valve 6 Evaporator 7 Case 11 Valve part 12 Power element 13 Pressure sensitive actuator 14 Body 14a Step part 15 Inlet port 16 Outlet port 17 Valve seat 18 Valve element 18a Guide 19 Spring 20 Shaft 20a Large diameter portion 20b Small diameter portion 21 O-ring 22 Diaphragm 23 Upper housing 24 Lower housing 25 Communication hole 26 Disc 27 Diaphragm 28 Upper housing 29 Lower housing 30 Fixing member 31 32 Center disk 33 Spring receiving member 34 Spring 35 Spring receiving member 36 O ring 41 V packing 42 Piston 43, 44 Cylindrical member 45 V packing 46 Communication hole 47 O ring 51 Cooling Inlet 52 Refrigerant outlet 53 Inlet piping 54 Connecting portion 55 O-ring 56 Connecting piping 57 Connecting member 57a U-shaped passage 57b Tubular portion 58 Fitting 58a First connecting hole 58b Second connecting hole 58c Third port Connection hole 58d Fourth connection hole 58e, 58f Screw hole 59 Connection portion 60 O-ring 61 Clamping device 61a First locking member 61b Second locking member 61c Fixing pin 71 Valve case 71a Stepped portion 72 Stopper 73 High-pressure introduction groove 74 , 75 Seal groove 76, 77 V packing 81 Low pressure inlet port 82 Low pressure outlet port 83 Pressure sensitive piston 83a Leg 84 Spring 85 Low pressure refrigerant passage 86 Shaft guide 87 Collar member 88 O-ring

Claims (9)

In the expansion valve that controls the flow rate of the refrigerant sent to the evaporator by sensing the temperature and pressure of the refrigerant at the outlet of the evaporator,
An expansion valve comprising a pressure-sensitive actuator that changes a set value in accordance with a differential pressure between the pressure of the refrigerant sent out to the evaporator and the pressure of the refrigerant returned from the evaporator.   The pressure-sensitive actuator is configured to change a direction in which the set value is increased by decreasing a load of a spring for adjusting a set value when the differential pressure exceeds a predetermined value. 1. The expansion valve according to 1.   The pressure sensitive actuator receives the pressure on the outlet port side in the valve opening direction, receives the pressure of the refrigerant returned from the evaporator in the valve closing direction, and when the differential pressure increases beyond the predetermined value, A diaphragm that is displaced in a direction to reduce the load; and an urging means that urges the diaphragm to be held at a predetermined displacement position until the differential pressure reaches the predetermined value. The expansion valve according to claim 2, wherein the diaphragm receives the other end of the spring biased in the valve closing direction.   The pressure sensitive actuator receives the pressure on the outlet port side in the valve opening direction, receives the pressure of the refrigerant returned from the evaporator in the valve closing direction, and when the differential pressure increases beyond the predetermined value, A piston that displaces in a direction to reduce the load; and an urging means that urges the piston to be held at a predetermined displacement position until the differential pressure reaches the predetermined value. The expansion valve according to claim 2, wherein the piston receives the other end of the spring biased in the valve closing direction.   The pressure sensitive actuator is slidably disposed in the valve case, receives the pressure on the outlet port side in a direction away from the spring, and receives the pressure of the refrigerant returned from the evaporator in a direction toward the spring. When the differential pressure increases beyond the predetermined value, the body slides in a direction to reduce the load of the spring, and is biased to hold the body in a predetermined position until the differential pressure reaches the predetermined value. And a spring receiving member that is fixed to the valve case at the other end of the spring that is biased in the valve closing direction with respect to the valve body. The expansion valve according to claim 2.   Housed in a case placed between an internal heat exchanger that exchanges heat between the high-temperature and high-pressure refrigerant sent from the receiver and the low-temperature and low-pressure refrigerant returned to the compressor inlet, and the evaporator In the case, the power element senses the temperature and pressure of the refrigerant introduced from the evaporator, and the inlet port is connected to a pipe that receives the high-temperature / high-pressure refrigerant from the internal heat exchanger, and the outlet port The expansion valve according to claim 2, wherein the expansion valve is a temperature type expansion valve connected to a refrigerant inlet of the evaporator.   2. The expansion valve according to claim 1, wherein the pressure-sensitive actuator changes in a direction in which the valve seat moves to increase the set value when the differential pressure increases beyond a predetermined value.   The pressure-sensitive actuator holds the valve seat, receives the pressure on the outlet port side in a direction away from the valve body, receives the pressure of the refrigerant returned from the evaporator in a direction approaching the valve body, and When the differential pressure increases beyond the predetermined value, the pressure-sensitive piston is displaced in a direction away from the valve body, and the pressure-sensitive piston is held at a predetermined displacement position until the differential pressure reaches the predetermined value. 8. The expansion valve according to claim 7, further comprising biasing means for biasing.   The valve portion includes a shaft that transmits a displacement of the diaphragm due to the power element sensing the temperature and pressure of the refrigerant at the outlet of the evaporator to a valve body disposed on the downstream side of the valve seat, A small-diameter portion that extends through the hole and is fixed to the valve body, and a large-diameter portion that has the same outer diameter as the inner diameter of the valve hole and receives the introduced high pressure in the valve-closing direction are integrally formed. 2. The expansion valve according to claim 1, wherein the high pressure formed and introduced is canceled.

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