JP2010112616A - Thermal expansion valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve refrigeration cycle characteristics through all load ranges by varying the charge characteristic of a thermal expansion valve which is uniquely determined by setting a set value in conformation to a thermal load placed on a heat exchanger. <P>SOLUTION: A bimetal 37 is arranged in a second refrigerant passage 15 through which outlet refrigerant of an evaporator 5 passes, and caused to sense the thermal load placed on the heat exchanger that is an air load of the evaporator 5. When the temperature of the refrigerant rises, the bimetal 37 works to push up a shaft 31 toward a power element 12 or to release the push-up of the shaft 31 toward the power element 12, whereby the set value is corrected in a descending or ascending direction. According to this, the charge characteristic can be set to characteristics suitable respectively to a middle and low load range and a high load range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a temperature-type expansion valve, and in particular, expands a high-temperature / high-pressure liquid refrigerant in a refrigeration cycle of an automotive air conditioner to form a low-temperature / low-pressure vapor refrigerant, and the superheat degree of the refrigerant at the outlet of the evaporator has a predetermined value. The present invention relates to a temperature-type expansion valve that controls the flow rate of refrigerant supplied to an evaporator so as to be maintained.

  In general, a refrigeration cycle of a vehicle air conditioner generally includes a compressor that compresses a circulating refrigerant, a condenser that condenses the compressed refrigerant, an excess refrigerant in the refrigeration cycle, and temporarily stores the condensed refrigerant. A receiver that separates the liquid, an expansion valve that squeezes and expands the separated liquid refrigerant, and an evaporator that evaporates the refrigerant expanded by the expansion valve are provided. The expansion valve is a temperature type expansion that senses the temperature and pressure of the refrigerant at the outlet of the evaporator and controls the flow rate of the refrigerant sent to the evaporator so that the evaporation state of the refrigerant at the evaporator outlet has a predetermined degree of superheat. A valve is used (see, for example, Patent Document 1).

  This temperature type expansion valve has a valve part that throttles and expands the refrigerant and controls the flow rate of the refrigerant, and a power element that controls the valve part by sensing the temperature and pressure of the refrigerant from the evaporator toward the compressor. . The power element has a temperature-sensing greenhouse in which the valve portion side is partitioned by a diaphragm, and the temperature-sensing chamber is filled with a gas that determines the opening characteristics of the temperature expansion valve. The power element is configured to introduce and expose the refrigerant that exits the evaporator to the diaphragm, and changes the pressure in the temperature-sensitive room according to the temperature and pressure of the introduced refrigerant, and transmits the displacement of the diaphragm to the valve unit. By doing so, the flow rate of the refrigerant sent out to the evaporator is feedback-controlled so that the degree of superheat of the introduced refrigerant maintains a predetermined value.

  FIG. 10 is a diagram showing the characteristics of the temperature type expansion valve. In FIG. 10, the horizontal axis indicates the temperature Te of the refrigerant at the evaporator outlet detected by the temperature sensitive room, and the vertical axis indicates the refrigerant pressure Pe at the evaporator outlet detected by the temperature sensitive room.

  A temperature type expansion valve can be made into a cross charge system by filling the temperature sensitive greenhouse with a gas different from the working refrigerant (for example, HFC-134a) of the refrigeration cycle. That is, the temperature-sensitive room is filled with a gas having a gentler slope than the saturation pressure characteristic of the refrigerant used in the refrigeration cycle, and the charge characteristic is A that intersects the refrigerant saturation curve in a low temperature range. In this cross-charge type temperature expansion valve, when the refrigerant temperature at the evaporator outlet is low and the load is low, the pressure in the temperature sensing cylinder becomes higher than the saturation vapor pressure curve of the refrigerant, and the valve portion does not close. As a result, the temperature expansion valve can pass the liquid refrigerant in which the lubricating oil for the compressor is dissolved at low load and return it to the compressor. Therefore, the refrigerant is circulated while the compressor is operating at a small capacity at low load. Even when the flow rate is small, sufficient oil circulation can be ensured, and seizure of the variable capacity compressor due to lack of lubricating oil can be prevented.

  Here, the temperature type expansion valve is adjusted according to the compressor characteristics and the like to determine how much superheat is to be maintained constant. The typical charge characteristic A is adjusted such that when the evaporator outlet temperature Te is 0 ° C., the evaporator outlet pressure Pe is 0.20 MPa and the temperature expansion valve is opened. The set value at this time is Pset, and the degree of superheat when the evaporator outlet temperature Te is set to 10 ° C. is SH. When it is desired to reduce the degree of superheat with respect to the charge characteristic A, by increasing the set value to Pset (h) = 0.24 MPa, the charge characteristic becomes A1, and the superheat degree becomes SH (s) (<SH). . Conversely, when it is desired to increase the degree of superheat with respect to the charge characteristic A, the set value is lowered to Pset (s) = 0.16 MPa. As a result, the charge characteristic becomes A2, and the superheat degree becomes SH (h) (> SH). In this way, the charge characteristic (the slope of the curve) is determined by the type of gas to be sealed, and the charge characteristic is shifted in parallel depending on how many set values are set, and the superheat degree is set to a desired value. be able to.

FIG. 11 is a diagram showing a change tendency of factors that change due to a change in the set value.
Consider the case where the set value is set to Pset. At low loads, the flow rate of the refrigerant circulating in the refrigeration cycle is originally low, so if the refrigerant flow rate is further reduced by lowering the set value, the refrigerant will not flow even with a slight disturbance, and the system tends to hunt. Yes, if the set value is increased, the hunting is less likely to occur. At medium load, if an electronic control valve or mechanical control valve is used for the compressor and its set value is set to a value close to the set value of the temperature expansion valve, a control conflict will occur and the system will However, the hunting tendency of the system can be improved by shifting the set value of the temperature type expansion valve up and down and shifting it from the set value of the compressor control valve. In addition, if a constant flow rate is passed through the evaporator at the standard set value at medium load, there is a lot of noise generated by the flow of refrigerant at that flow rate. When the distribution of gas and liquid is closer to the liquid or gas side, the resonance frequency may be shifted and noise of annoying frequency components may be reduced. At high loads, the standard set value is superior in both system efficiency and cooling power, and lowering the set value decreases both system efficiency and cooling power, increasing the set value and increasing the flow rate, When a large amount of refrigerant is sucked, the compression efficiency is drastically reduced, so that both the system efficiency and the cooling power tend to further decrease. When the set value is lowered, the durability of the compressor draws in the refrigerant that has become too superheated, so the temperature of the discharged refrigerant also rises, exceeding the allowable operating temperature of the lubricating oil, and destroying the compressor There is a tendency to lead to. On the contrary, when the set value is increased, the degree of superheat is only slightly reduced, and the durability of the compressor is not adversely affected.

From the above, the most important thing as a vehicle air conditioner is that the necessary cooling power can be obtained and the compressor does not break in the high load area where the capacity of the vehicle air conditioner is required. Therefore, the set value is inevitably set to a value that satisfies this condition.
JP 2002-115938 A

  However, the charge characteristics of the temperature expansion valve are uniquely determined by the set value set according to the type of the enclosed gas and the characteristics of the high load area. However, even though they have excellent characteristics, there was a problem that they had to be sacrificed.

  This invention is made | formed in view of such a point, and it aims at providing the temperature type expansion valve which can improve the characteristic of a refrigerating cycle through a full load area | region.

  In the present invention, in order to solve the above problem, in the temperature type expansion valve that controls the flow rate of the refrigerant supplied to the evaporator so that the degree of superheat of the refrigerant at the outlet of the evaporator maintains a predetermined value, heat exchange of the refrigeration cycle There is provided a temperature type expansion valve characterized by including a temperature sensitive actuator that senses a temperature corresponding to a heat load applied to the vessel and varies a set value that determines a charge characteristic according to the temperature. .

  According to such a temperature type expansion valve, the temperature-sensitive actuator corrects the set value based on the temperature that changes in response to the heat load applied to the heat exchanger of the refrigeration cycle. Thereby, the charge characteristic of the temperature type expansion valve can be set to a characteristic superior to the conventional characteristic in the medium and low load areas while maintaining the conventional characteristic in the high load area.

  The temperature type expansion valve with the above configuration can set the charge characteristics of the temperature type expansion valve separately in the high load region and the medium and low load region, so the set value that generates noise in the evaporator at medium load is set. It can be set by shifting. Moreover, since the set value can be changed so as to increase the flow rate at low load, hunting at low load can be prevented. In addition, when the set value of the compressor control valve and the set value of the temperature type expansion valve are set close to each other, hunting may occur when both valves operate and repeat opening and closing. By making the set value of the expansion valve variable, hunting due to competing control of both valves can be avoided.

  Hereinafter, referring to the drawings, an embodiment of the present invention is used as an example of an expansion device having a function of controlling the degree of superheat of a refrigerant (HFC-134a) at an evaporator outlet in a refrigeration cycle of a vehicle air conditioner. And will be described in detail.

FIG. 1 is a system diagram of a refrigeration cycle showing a thermal expansion valve according to a first embodiment in a central longitudinal sectional view. In addition, the arrow in a figure has shown the flow direction of the refrigerant | coolant.
The automotive air conditioner includes a compressor 1 that compresses refrigerant, a capacitor 2 that condenses the compressed refrigerant by heat exchange with outside air, and a receiver 3 that temporarily stores the condensed refrigerant and separates it into gas and liquid. And a temperature type expansion valve 4 that squeezes and expands the separated liquid refrigerant, and an evaporator 5 that evaporates the squeezed and expanded mist-like refrigerant by heat exchange with the air in the passenger compartment, and is evaporated by the evaporator 5. The refrigerant is returned to the compressor 1 to constitute a refrigeration cycle in which the refrigerant circulates.

  The temperature type expansion valve 4 constituting the refrigeration cycle includes a valve unit 11 that squeezes and expands the high-temperature and high-pressure liquid refrigerant supplied from the receiver 3 and sends it to the evaporator 5 as a low-temperature and low-pressure mist refrigerant, and an evaporator. And a power element 12 that senses the temperature and pressure of the refrigerant that has exited 5 and controls the flow rate of the refrigerant that is sent to the evaporator 5 by the valve unit 11 so that the superheat degree of the sensed refrigerant is maintained at a predetermined value. .

  The valve part 11 of the temperature type expansion valve 4 has a block-shaped body 13. The body 13 has a first refrigerant passage 14 for flowing the refrigerant from the receiver 3 to the evaporator 5 and a second refrigerant passage 15 for flowing the refrigerant from the evaporator 5 to the compressor 1. The first refrigerant passage 14 has a high-pressure inlet port 16 to which high-pressure piping is connected and a low-pressure outlet port 17 to which low-pressure piping is connected at both ends, and a valve hole 18 in the longitudinal direction of the body 13 in the middle thereof. Is formed. On the high-pressure side of the valve hole 18, a valve body 19 that allows the valve hole 18 to be opened and closed is disposed. The valve body 19 is urged by a spring 21 through a valve body receiver 20 in a direction to close the valve hole 18. ing.

  A valve chamber that accommodates the valve body 19 is formed in the body 13 in the same direction as the valve hole 18, and an adjustment screw 22 is screwed into an opening end thereof so as to be able to advance and retreat in the axial direction, and is sealed by an O-ring 23. It is closed by being done. A spring receiving member 24 is fitted to the adjustment screw 22 and receives the end of the spring 21 opposite to the valve body receiver 20. The adjustment screw 22 can adjust the spring load of the spring 21 by adjusting the amount of screwing into the body 13, thereby adjusting the set value and adjusting the degree of superheat.

  The second refrigerant passage 15 has, at both ends thereof, a return low pressure inlet port 25 to which a return low pressure pipe from the evaporator 5 is connected and a return low pressure outlet port 26 to which a return low pressure pipe to the compressor 1 is connected. .

  The power element 12 is coupled to the top surface of the body 13 by screwing. The power element 12 is formed by arranging an upper housing 28 and a lower housing 29 on both sides of the diaphragm 27 and welding the outer peripheral edges thereof together. A room surrounded by the upper housing 28 and the diaphragm 27 is filled with a gas having characteristics similar to the refrigerant of the refrigeration cycle, and senses the temperature and pressure of the refrigerant passing through the second refrigerant passage 15. Is configured. In the lower housing 29, a center disk 30 that is in contact with the center of the lower surface of the diaphragm 27 is disposed. The center disk 30 transmits the displacement of the diaphragm 27 due to the pressure in the temperature-sensitive room changing according to the temperature and pressure of the refrigerant introduced into the second refrigerant passage 15 to the valve body 19 via the shaft 31. Is for.

  The shaft 31 extends across the second refrigerant passage 15 to the valve portion 11, and the upper end thereof is held by the holder 32 accommodated in the upper portion of the figure of the body 13, so that the middle is the first refrigerant passage 14 and the second refrigerant. A through hole 33 formed in the body 13 between the refrigerant passages 15 is held so as to be able to advance and retract in the opening and closing direction of the valve body 19. The lower end of the shaft 31 is in contact with the valve body 19 through the valve hole 18.

  On the side of the second refrigerant passage 15 of the through-hole 33, there is a space portion 34 that is formed with a gradually increasing diameter, and on the valve portion 11 side of the space portion 34, the first refrigerant passage 14 and An O-ring 35 for preventing the refrigerant from leaking to and from the second refrigerant passage 15 is disposed, and a stop for preventing the O-ring 35 from dropping into the second refrigerant passage 15 adjacent to the O-ring 35. A ring 36 is locked to the inner wall of the space 34. A bimetal 37 serving as a temperature-sensitive actuator is disposed at the opening of the space 34 to the second refrigerant passage 15, and the outer peripheral edge thereof is restrained by a ring-shaped stopper 38. The bimetal 37 has a through hole through which the shaft 31 passes in the center. The shaft 31 is fitted with an E-ring-shaped retaining ring 39 that engages with and disengages from the surface of the bimetal 37 on the power element 12 side. In the bimetal 37, the inner peripheral edge of the through hole depends on temperature and is displaced in the axial direction of the shaft 31 with the outer peripheral edge serving as a fulcrum, and cooperates with the spring 21 for adjusting the set value.

  In the temperature type expansion valve 4 having the above configuration, when the automobile air conditioner is operating, the high-pressure liquid refrigerant introduced from the receiver 3 to the high-pressure inlet port 16 closes the valve body 19 and the valve hole 18. It flows through the clearance between the valve seat and the valve seat 18 that is sometimes seated, and is then expanded by being squeezed and expanded into a mist-like low-temperature / low-pressure refrigerant, which is sent out from the low-pressure outlet port 17 to the evaporator 5. The refrigerant evaporated by the evaporator 5 is introduced into the temperature type expansion valve 4 from the return low-pressure inlet port 25, and sent from the return low-pressure outlet port 26 to the inlet of the compressor 1 through the second refrigerant passage 15. At this time, a part of the refrigerant passing through the second refrigerant passage 15 is introduced into the lower housing 29, and the temperature and pressure of the refrigerant introduced by the power element 12, that is, the degree of superheat, is sensed. In the power element 12, for example, at a high load when the discharge capacity of the compressor 1 is large and heat exchange in the evaporator 5 increases, the temperature of the refrigerant introduced from the evaporator 5 increases, so that the temperature type expansion valve 4 senses pressure. The pressure in the sensitive room becomes relatively higher than the pressure in the lower housing 29. As a result, the diaphragm 27 is displaced toward the valve portion 11, and the displacement acts to urge the valve body receiver 20 in the valve opening direction via the shaft 31 and increase the flow rate of the refrigerant sent to the evaporator 5. . On the contrary, at the time of medium and low loads in which the temperature of the refrigerant introduced from the evaporator 5 is low, the power element 12 acts to reduce the flow rate of the refrigerant sent to the evaporator 5. As a result, the temperature type expansion valve 4 controls the flow rate of the refrigerant sent to the evaporator 5 so that the superheat degree of the outlet refrigerant of the evaporator 5 maintains the predetermined value set by the spring 21 for adjusting the set value. Become. Next, the operation of the bimetal 37 cooperating with the set value adjusting spring 21 will be described.

FIG. 2 is a graph showing the characteristics of the temperature type expansion valve according to the first embodiment.
The bimetal 37 operates by sensing the temperature of the refrigerant passing through the second refrigerant passage 15, that is, the refrigerant at the outlet of the evaporator 5. Here, the bimetal 37 has a different direction of bending as the sensed temperature increases depending on the bonding direction of two kinds of metals having different thermal expansion coefficients. In the case of having the first characteristic that the center portion is displaced to the power element 12 side from the outer peripheral edge portion as the temperature increases, a metal having a small thermal expansion coefficient is set to the valve portion 11 side, A case will be described in which the center portion has a second characteristic in which the center portion is displaced from the outer peripheral edge portion toward the valve portion 11 as the height increases. As an example, the bimetal 37 is formed in the shape of a disc spring, and the bimetal 37 is used in which the positional relationship between the central portion and the outer peripheral edge portion is reversed at a certain temperature.

  In the temperature type expansion valve 4 using the bimetal 37 having the first characteristic, the set value adjusting spring 21 is adjusted so that the set value becomes Pset (h), and the temperature (0 (° C.), the bimetal 37 is installed at a position not in contact with the retaining ring 39. When the temperature of the refrigerant at the outlet of the evaporator 5 becomes high and enters a high load region, in this example, 10 ° C., the bimetal 37 reverses and acts to push up the retaining ring 39 toward the power element 12. As a result, the spring load of the spring 21 for adjusting the set value is biased in an increasing direction, and the set value is lowered from Pset (h) to the standard Pset by correcting the spring load. It will be.

  Therefore, in the temperature type expansion valve 4 using the bimetal 37 having the first characteristic for sensing the temperature of the refrigerant in the second refrigerant passage 15, it corresponds to the air load of the evaporator 5, that is, the heat load applied to the heat exchanger. Thus, the set value has a charge characteristic A (h) that becomes high in the middle and low load region. This means that, in the graph showing the change tendency of the factors that change due to the change of the set value in FIG. 11, it is possible to enjoy the advantage in the medium and low load region due to the high set value.

  In the temperature type expansion valve 4 using the bimetal 37 having the second characteristic described above, the spring 21 for adjusting the set value is adjusted so that the set value becomes Pset (s). At (0 ° C.), the bimetal 37 is reversed from the illustrated state, and is installed at a position that acts to push up the retaining ring 39 toward the power element 12. When the temperature of the refrigerant at the outlet of the evaporator 5 rises to a temperature that enters the high load region, the bimetal 37 is reversed and substantially separated from the retaining ring 39 as shown in the figure. As a result, since the spring load of the spring 21 for adjusting the set value is biased in the direction of decreasing, the set value becomes the same as when the set value is increased from Pset (s) to the standard Pset.

  Therefore, in the temperature type expansion valve 4 using the bimetal 37 having the second characteristic that senses the temperature of the refrigerant in the second refrigerant passage 15, it corresponds to the heat load applied to the heat exchanger that is the air load of the evaporator 5. The charge characteristic A (s) becomes lower in the set value in the middle / low load region. This means that, in the graph showing the change tendency of the factors that change due to the change of the set value in FIG. 11, it is possible to enjoy the advantage in the medium and low load region by setting the set value low. FIG. 11 shows that the hunting of the system generally has a tendency to deteriorate when the set value is lowered in the low load region. However, a compressor 1 that does not easily cause hunting is used. Thus, it is possible to use the temperature type expansion valve 4 having the charge characteristic A (s).

  In the above example, the bimetal 37 in the shape of a disc spring is shown to perform a snap operation in which the positions of the central portion and the outer peripheral edge are reversed at a certain temperature, but it is used in a region where the snap operation is not performed. Thus, the inflection point at the boundary between the medium load region and the high load region in the charge characteristics A (h) and A (s) can be smoothed.

  FIG. 3 is a central longitudinal sectional view showing the configuration of the temperature type expansion valve according to the second embodiment. In FIG. 3, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The thermal expansion valve 4a according to the second embodiment has the axial positional relationship between the bimetal 37 and the retaining ring 39 reversed as compared with the thermal expansion valve 4 according to the first embodiment. Is. Therefore, in the case of the temperature type expansion valve 4a having the above first characteristic in the bimetal 37, the charge characteristic is A (s), and in the case of the temperature type expansion valve 4a having the above second characteristic, the charge characteristic is A (h).

  FIG. 4 is a central longitudinal sectional view showing the configuration of the temperature type expansion valve according to the third embodiment. In FIG. 4, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The temperature type expansion valve 4b according to the third embodiment uses a shape memory alloy spring 40 as a temperature sensitive actuator as compared with the temperature type expansion valves 4 and 4a according to the first and second embodiments. Is different in that That is, the shape memory alloy spring 40 is disposed in the space portion 34, one end of which is locked to the retaining ring 39, and the other end is locked to the bottom surface of the space portion 34. The shape memory alloy spring 40 is made of, for example, a Ni—Ti-based shape memory alloy, and its transformation point is matched with the inflection point of the charge characteristics.

  In the temperature type expansion valve 4b using the shape memory alloy spring 40, the set value adjusting spring 21 is adjusted so that the set value becomes Pset (h), and the temperature (0 ° C.) at the time of this set value adjustment. Then, the spring load of the shape memory alloy spring 40 is small, and there is no force to push the retaining ring 39 toward the power element 12 side. When the temperature of the refrigerant at the outlet of the evaporator 5 becomes high and enters a high load region, the shape memory alloy spring 40 increases its spring load and acts to push up the shaft 31 toward the power element 12. As a result, the spring load of the spring 21 for adjusting the set value is biased in an increasing direction, so that the set value becomes the same as when the set value is lowered from Pset (h) to the standard Pset.

  Therefore, the temperature type expansion valve 4 b using the shape memory alloy spring 40 that senses the temperature of the refrigerant in the second refrigerant passage 15 is set in accordance with the heat load applied to the heat exchanger that is the air load of the evaporator 5. Has a charge characteristic A (h) that decreases in a high load region.

  FIG. 5 is a central longitudinal sectional view showing the configuration of the temperature type expansion valve according to the fourth 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 temperature type expansion valve 4c according to the fourth embodiment has a shape memory alloy spring 40 connected to the shaft 31 in the second refrigerant passage 15 as compared with the temperature type expansion valve 4b according to the third embodiment. Is arranged so as to push down toward the valve part 11 side. That is, the shape memory alloy spring 40 is disposed between the holder 32 and the retaining ring 39 locked to the shaft 31.

  In the temperature type expansion valve 4c, the set value adjusting spring 21 is adjusted so that the set value becomes Pset (s). At the temperature (0 ° C.) at the time of adjusting the set value, the shape memory alloy spring 40 is used. The spring load is small, and there is no force to push down the retaining ring 39 toward the valve portion 11. When the temperature of the refrigerant at the outlet of the evaporator 5 rises to a temperature that enters a high load region, the shape memory alloy spring 40 increases its spring load and acts to push down the shaft 31 toward the valve portion 11. As a result, since the spring load of the spring 21 for adjusting the set value is biased in the direction of decreasing, the set value becomes the same as when the set value is increased from Pset (s) to the standard Pset.

  Therefore, the temperature type expansion valve 4c using the shape memory alloy spring 40 has a charge characteristic A (s) in which the set value increases in a high load region corresponding to the heat load applied to the heat exchanger that is the air load of the evaporator 5. Will have.

  FIG. 6 is a central longitudinal sectional view showing the configuration of the temperature type expansion valve according to the fifth embodiment. In FIG. 6, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the temperature type expansion valve 4d according to the fifth embodiment, the temperature type expansion valves 4, 4a, 4b, and 4c according to the first to fourth embodiments detect the air load of the evaporator 5 as temperature sensitive actuators. The second refrigerant passage 15 is different from the first refrigerant passage 14 in that it is arranged in the high pressure side of the first refrigerant passage 14 that can detect the air load of the condenser 2. Yes. That is, the bimetal 37 that is a temperature-sensitive actuator is disposed in the valve chamber so that the inner peripheral edge of the central through hole is locked to the valve body receiver 20 and the outer peripheral edge is locked to the body 13. In the fifth embodiment, since the temperature of the refrigerant exiting the condenser 2 varies greatly depending on the outside air temperature, the heat load applied to the heat exchanger can be detected in correspondence with the temperature of the high-pressure refrigerant. The set value is to be changed according to the temperature.

  In the temperature type expansion valve 4d using the bimetal 37 having the first characteristic, the set value adjusting spring 21 is adjusted so that the set value becomes Pset (h). Then, the bimetal 37 is installed in the position which is hardly in contact with the valve body receiver 20. When the temperature of the high-pressure refrigerant introduced into the high-pressure inlet port 16 rises and reaches a high load region, the bimetal 37 reverses and acts to push up the valve body receiver 20 toward the power element 12. As a result, the spring load of the spring 21 for adjusting the set value is biased in the increasing direction, and the set value is lowered from Pset (h) to the standard Pset.

  Therefore, in the temperature type expansion valve 4d using the bimetal 37 having the first characteristic, the charge characteristic in which the set value becomes high in the middle / low load region corresponding to the air load of the capacitor 2, that is, the heat load applied to the heat exchanger. Will have A (h).

  In the temperature type expansion valve 4d using the bimetal 37 having the second characteristic described above, the set value adjusting spring 21 is adjusted so that the set value becomes Pset (s). Then, the bimetal 37 is reversed from the illustrated state, and is installed at a position that acts to push up the valve body receiver 20 toward the power element 12. When the temperature of the high-pressure refrigerant rises to a temperature that enters a high load region, the bimetal 37 is reversed and substantially separated from the valve body receiver 20 as shown in the figure. As a result, since the spring load of the spring 21 for adjusting the set value is biased in the direction of decreasing, the set value becomes the same as when the set value is increased from Pset (s) to the standard Pset.

  Therefore, in the temperature type expansion valve 4d using the bimetal 37 having the second characteristic for sensing the temperature of the high-pressure refrigerant, the set value corresponds to the heat load applied to the heat exchanger, which is the air load of the capacitor 2, at a medium to low load It has a charge characteristic A (s) that decreases in the region.

  FIG. 7 is a central longitudinal sectional view showing the configuration of the temperature type expansion valve according to the sixth embodiment. In FIG. 7, the same components as those shown in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The temperature type expansion valve 4e according to the sixth embodiment is different in that the temperature memory actuator of the temperature type expansion valve 4d according to the fifth embodiment is a shape memory alloy spring 40. That is, the shape memory alloy spring 40 is disposed between the valve body receiver 20 and the spring receiver member 24 in the valve chamber.

  In this temperature type expansion valve 4e, the spring 21 for adjusting the set value is adjusted so that the set value becomes Pset (h). At the temperature at which this set value is adjusted, the spring load of the shape memory alloy spring 40 is It is small, and there is no force to push the valve body receiver 20 to the power element 12 side. When the temperature of the high-pressure refrigerant becomes high and enters a high load region, the shape memory alloy spring 40 increases its spring load and acts to push the valve element receiver 20 toward the power element 12. As a result, the spring load of the spring 21 for adjusting the set value is biased in an increasing direction, so that the set value becomes the same as when the set value is lowered from Pset (h) to the standard Pset.

  Therefore, the temperature type expansion valve 4e using the shape memory alloy spring 40 that senses the temperature of the high-pressure refrigerant has a low set value in the high load region corresponding to the heat load applied to the heat exchanger that is the air load of the capacitor 2. The charge characteristic A (h) is as follows.

  FIG. 8 is a central longitudinal sectional view showing the configuration of the temperature type expansion valve according to the seventh embodiment. In FIG. 8, the same components as those shown in FIG. 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The temperature type expansion valve 4f according to the seventh embodiment is different from the temperature type expansion valve 4e according to the sixth embodiment in that the installation position of the shape memory alloy spring 40 is changed. ing. That is, the shape memory alloy spring 40 is disposed in the valve chamber between the valve body receiver 20 and the annular groove that is recessed around the valve hole 18.

  In this temperature type expansion valve 4f, the spring 21 for adjusting the set value is adjusted so that the set value becomes Pset (s). At the temperature at which this set value is adjusted, the spring load of the shape memory alloy spring 40 is It is small and there is no force to push down the valve body receiver 20 in the valve opening direction. When the temperature of the high-pressure refrigerant becomes high and the temperature enters the high load region, the shape memory alloy spring 40 increases its spring load and acts to push down the valve body receiver 20 in the valve opening direction. As a result, since the spring load of the spring 21 for adjusting the set value is biased in the direction of decreasing, the set value becomes the same as when the set value is increased from Pset (s) to the standard Pset.

  Therefore, the temperature type expansion valve 4f using the shape memory alloy spring 40 has a charge characteristic A (s) in which the set value increases in a high load region corresponding to the heat load applied to the heat exchanger that is the air load of the capacitor 2. Will have.

  FIG. 9 is a central longitudinal sectional view showing the structure of the temperature type expansion valve according to the eighth embodiment. In FIG. 9, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The thermal expansion valve 4g according to the eighth embodiment indirectly senses the air load of the evaporator 5 by sensing the heat load applied to the heat exchanger on the low pressure side of the first refrigerant passage 14. Is. That is, when the passenger compartment temperature rises, more refrigerant emanates from the condenser 2 evaporates and the pressure rises, but this also increases the pressure on the inlet side of the condenser 2. Since the inlet side of the condenser 2 is a region where gas and liquid exist, the pressure and temperature of the refrigerant change along its saturation curve. For this reason, if the pressure of the refrigerant on the inlet side of the condenser 2 increases, the temperature rises accordingly, so that the temperature type expansion valve 4g is provided on the inlet side of the condenser 2, that is, the refrigerant on the low pressure outlet port 17. Is detected as a heat load applied to the heat exchanger, and the set value is changed in accordance with the temperature.

  Therefore, the temperature type expansion valve 4g is recessed around the open end of the retaining ring 39 and the through hole 33 in which the shape memory alloy spring 40 is locked to the shaft 31 in the room communicating with the low pressure outlet port 17. It is arrange | positioned between the recessed parts. Since the shape memory alloy spring 40 is incorporated from the valve chamber side, the valve seat member 41 is press-fitted into a hole through which the retaining ring 39 and the shape memory alloy spring 40 are passed to constitute the valve hole 18.

  In this temperature type expansion valve 4e, the spring 21 for adjusting the set value is adjusted so that the set value becomes Pset (s). At the temperature at which this set value is adjusted, the spring load of the shape memory alloy spring 40 is It is small and there is no force to push down the shaft 31 toward the valve body 19. When the temperature of the low-pressure refrigerant immediately after expansion becomes high and the temperature enters the high load region, the shape memory alloy spring 40 increases its spring load and acts to push down the shaft 31 toward the valve body 19. As a result, since the spring load of the spring 21 for adjusting the set value is biased in the direction of decreasing, the set value becomes the same as when the set value is increased from Pset (s) to the standard Pset.

  Therefore, the temperature type expansion valve 4e using the shape memory alloy spring 40 that senses the temperature of the low-pressure refrigerant has a high set value in a high load region corresponding to the heat load applied to the heat exchanger that is the air load of the evaporator 5. The charge characteristic A (s) is as follows.

  The temperature type expansion valve 4g according to the eighth embodiment uses the shape memory alloy spring 40 as a temperature-sensitive actuator that senses the temperature of the low-pressure refrigerant and corrects the spring load of the spring 21. It is also possible to comprise with bimetal like this form.

1 is a system diagram of a refrigeration cycle in which a thermal expansion valve according to a first embodiment is shown in a central longitudinal sectional view. It is a figure which shows the characteristic of the temperature type expansion valve which concerns on 1st Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the temperature type expansion valve which concerns on 2nd Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the temperature type expansion valve which concerns on 3rd Embodiment. It is a center longitudinal section showing the composition of the temperature type expansion valve concerning a 4th embodiment. It is a center longitudinal cross-sectional view which shows the structure of the temperature type expansion valve which concerns on 5th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the temperature type expansion valve which concerns on 6th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the temperature type expansion valve which concerns on 7th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the temperature type expansion valve which concerns on 8th Embodiment. It is a figure which shows the characteristic of a temperature type expansion valve. It is a figure which shows the change tendency of the factor which changes by the change of a set value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Capacitor 3 Receiver 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g Thermal expansion valve 5 Evaporator 11 Valve part 12 Power element 13 Body 14 1st refrigerant path 15 2nd refrigerant path 16 High pressure inlet Port 17 Low pressure outlet port 18 Valve hole 19 Valve body 20 Valve body receiver 21 Spring 22 Adjustment screw 23 O-ring 24 Spring receiving member 25 Return low pressure inlet port 26 Return low pressure outlet port 27 Diaphragm 28 Upper housing 29 Lower housing 30 Center disk 31 Shaft 32 Holder 33 Through-hole 34 Space 35 O-ring 36 Retaining ring 37 Bimetal 38 Stopper 39 Retaining ring 40 Shape memory alloy spring 41 Valve seat member

Claims (10)

In the temperature type expansion valve for controlling the flow rate of the refrigerant supplied to the evaporator so that the superheat degree of the refrigerant at the evaporator outlet maintains a predetermined value,
Thermal expansion that features a temperature-sensitive actuator that senses the temperature corresponding to the heat load applied to the heat exchanger of the refrigeration cycle and varies the set value that determines the charge characteristics according to that temperature valve.   The temperature-sensitive actuator corrects the load of the spring for adjusting the set value so as to set a standard characteristic in a high load region and to a characteristic shifted from the standard characteristic in a low load region. The temperature type expansion valve according to claim 1.   The temperature-sensitive actuator is installed in a refrigerant passage that allows the refrigerant from the evaporator to the compressor to pass therethrough, and senses the temperature of the refrigerant at the evaporator outlet corresponding to the air load of the evaporator to correct the load of the spring. The temperature type expansion valve according to claim 2, wherein the temperature type expansion valve is one.   The temperature-sensitive actuator is a bimetal disposed across the refrigerant passage and locked to a shaft that transmits changes in temperature and pressure of the refrigerant passing through the refrigerant passage to a valve body, and the bimetal is the refrigerant. The temperature type expansion valve according to claim 3, wherein the load of the spring is corrected by applying an axial load to the shaft in accordance with the temperature of the refrigerant passing through the passage.   The temperature-sensitive actuator is a shape memory alloy spring that is disposed across the refrigerant passage and is engaged with a shaft that transmits changes in the temperature and pressure of the refrigerant that passes through the refrigerant passage to the valve body. The temperature type expansion valve according to claim 3, wherein the memory alloy spring corrects the load of the spring by applying an axial load to the shaft in accordance with a temperature of the refrigerant passing through the refrigerant passage.   3. The temperature sensitive actuator is installed in a space where high pressure refrigerant from a capacitor is introduced, and senses the temperature of the high pressure refrigerant corresponding to the air load of the capacitor to correct the spring load. Temperature type expansion valve.   The temperature-sensitive actuator is a bimetal that is locked to the valve body in the valve chamber, and the bimetal corrects the load of the spring by applying a load in the opening / closing direction to the valve body according to the temperature of the high-pressure refrigerant. The temperature type expansion valve according to claim 3, wherein the temperature type expansion valve is provided.   The temperature-sensitive actuator is a shape memory alloy spring that is locked to the valve body in the valve chamber, and the shape memory alloy spring applies a load in the opening / closing direction to the valve body in accordance with the temperature of the high-pressure refrigerant. The temperature type expansion valve according to claim 3, wherein the load of the spring is corrected.   The temperature-sensitive actuator is installed in a low-pressure outlet space for sending the expanded low-pressure refrigerant to the evaporator, and senses the temperature of the low-pressure refrigerant that indirectly corresponds to the air load of the evaporator and corrects the load of the spring. The temperature type expansion valve according to claim 2.   The temperature-sensitive actuator is a shape memory alloy spring that is disposed in the low-pressure outlet space and is engaged with a shaft that transmits changes in temperature and pressure of the refrigerant passing through the refrigerant passage to the valve body, and the shape memory alloy The temperature type expansion valve according to claim 9, wherein the spring corrects a load of the spring by applying an axial load to the shaft in accordance with a temperature of the low-pressure refrigerant.

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