JP2007240138A - Expansion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion device which controls high pressure-side pressure such that the pressure does not exceed a predetermined pressure in terms of absolute pressure, while operating in response to differential pressure between pressure at an inlet thereof and pressure at an outlet thereof. <P>SOLUTION: This expansion device 3 comprises an orifice 28 for expanding refrigerant, a valve element 25 disposed on a downstream side of a valve hole 24 and urged by a shape-memory alloy spring 26 in a valve-opening direction, a shaft 29 disposed to extend through the valve hole 24 and having one end thereof rigidly fixed to the valve element 25, and a spring 31 provided at the other end of the shaft 29, and receiving load in the valve opening direction by differential pressure between pressure at the inlet and pressure at the outlet. The shape-memory alloy spring 26 senses the temperature of refrigerant on the downstream side to perform temperature-dependent correction of a set value of the differential pressure for opening the valve element 25. Therefore, pressure on an upstream side is controlled as if by absolute pressure. Further, when the pressure on the upstream side exceeds a predetermined pressure, the spring 31 is bent to open the expansion valve in this expansion valve 3, and hence the pressure is prevented from rising above the predetermined pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an expansion device, and more particularly to an expansion device that expands a refrigerant in a refrigeration cycle of a vehicle air conditioner.

  In a vehicle air conditioner, a refrigeration cycle using carbon dioxide or the like as a refrigerant used in the refrigeration cycle has been proposed due to the problem of the global environment. In the refrigeration cycle using carbon dioxide as a refrigerant, the operating pressure is high, so that the constituent elements constituting the refrigeration cycle have a pressure-resistant structure so as to withstand high pressure. Further, in a compressor that compresses a refrigerant and an expansion device that expands the compressed refrigerant, when the high pressure of the refrigerant enters a dangerous pressure-resistant region, the pressure is controlled to decrease or the pressure is decreased. It has been done to make a structure that can.

  For example, in the expansion device, the pressure on the high pressure side of the refrigerant inlet is compared with the atmospheric pressure, and when the pressure on the high pressure side exceeds a predetermined pressure, the valve is opened to reduce the pressure on the high pressure side Is known (for example, see Patent Document 1). According to this expansion device, a bellows that is reduced as the refrigerant pressure rises due to the refrigerant pressure introduced to the refrigerant inlet of the expansion device to the outside and that is opened to the atmosphere inside, and opened as the bellows is reduced. And a valve mechanism for valve. As a result, the bellows compares the high-pressure side refrigerant pressure introduced into the refrigerant inlet of the expansion device with the atmospheric pressure, and if the refrigerant pressure becomes higher than a predetermined pressure that is dangerous for the refrigeration cycle, the bellows In response, the valve mechanism is proportionally opened to reduce the pressure. In this way, the bellows senses the pressure on the high pressure side of the refrigerant inlet as an absolute pressure and controls the valve mechanism, so that it is possible to prevent the pressure on the high pressure side of the refrigerant inlet from becoming higher than a predetermined pressure to some extent. .

  Further, according to Patent Document 1, there is also disclosed an expansion device having a differential pressure control valve structure that operates with a differential pressure between a refrigerant inlet and a refrigerant outlet instead of sensing the pressure on the high pressure side with an absolute pressure. When the pressure difference between the inlet and the refrigerant outlet exceeds a predetermined pressure, the valve is opened to reduce the pressure at the refrigerant inlet.

In this way, by configuring the expansion device so that the pressure on the high-pressure side is limited, there is no fear that the pressure on the high-pressure side becomes an abnormally high pressure. In addition, the high pressure on the high pressure side is when high refrigeration capacity is required. In such a case, the compressor is operating at the maximum discharge capacity, and the pressure on the high pressure side exceeds the predetermined pressure. Even in such a case, since it is not necessary to control the discharge pressure to be reduced on the compressor side, it is possible to efficiently operate the compressor at a high discharge pressure and maintain a high refrigeration capacity.
JP 2004-142701 A (FIGS. 2 and 5)

  However, in conventional expansion devices that use bellows, the pressure on the high pressure side can be sensed and controlled by absolute pressure, but the pressure resistance of the bellows that directly receives high pressure must be taken into account. In the case of the pressure control valve structure, the pressure on the high pressure side is expressed by a value obtained by adding the pressure on the low pressure side to the pressure difference between the refrigerant inlet and the refrigerant outlet. If it changes, it will be directly affected by it, so there is a problem that it cannot be managed with absolute pressure.

  The present invention has been made in view of the above points, and functions as a pressure relief valve when the pressure on the high-pressure side exceeds a predetermined pressure as an absolute pressure while operating with a differential pressure between the inlet pressure and the outlet pressure. An object of the present invention is to provide an expansion device.

  In the present invention, in order to solve the above problem, in the expansion device for expanding the refrigerant circulating in the refrigeration cycle, a differential pressure control valve opened by a differential pressure between the upstream pressure and the downstream pressure of the refrigerant; A spring arranged to urge the differential pressure control valve in the valve closing direction so that the differential pressure control valve is opened when the differential pressure exceeds a predetermined value; And an actuator that corrects the predetermined value of the differential pressure that is opened by the differential pressure control valve in response to a change in temperature or pressure of the refrigerant.

  According to such an expansion device, the actuator is configured to correct a predetermined value of the differential pressure at which the differential pressure control valve opens in accordance with a change in temperature or pressure of the refrigerant on the downstream side. As a result, the pressure on the downstream side of the differential pressure control valve is sensed as a pressure corresponding to the outlet temperature by the actuator or directly sensed by the actuator. Behaves as if the inlet pressure is controlled by absolute pressure. When the inlet pressure on the high pressure side exceeds the predetermined pressure, the spring is bent and the differential pressure control valve is suddenly opened to release the high pressure pressure downstream, so that the inlet pressure is maintained at the predetermined pressure and beyond The inlet pressure will not increase.

  The expansion device of the present invention corrects a predetermined value of the differential pressure that opens the differential pressure control valve in accordance with a change in temperature or pressure of the downstream refrigerant detected by the actuator, that is, the differential pressure control valve. Because the set differential pressure is corrected with the temperature or pressure on the low pressure side, the inlet pressure on the high pressure side is not affected by the pressure on the low pressure side even though the differential pressure control valve operates with the differential pressure. There is an advantage that it is possible to operate as if it is detected by absolute pressure.

  Even if the inlet pressure exceeds the predetermined pressure depending on the operating condition of the compressor, if the inlet pressure exceeds the predetermined pressure, the spring bends and the differential pressure control valve opens suddenly. Since the inlet pressure is reduced, the inlet pressure is maintained at the predetermined pressure, and a situation where the high pressure side becomes abnormally high can be reliably avoided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking as an example an expansion device applied to a refrigeration cycle using carbon dioxide as a refrigerant.
1 is a system diagram showing a refrigeration cycle to which an expansion device according to a first embodiment is applied, FIG. 2 is a Mollier diagram of carbon dioxide, and FIG. 3 shows a configuration of the expansion device according to the first embodiment. FIG. 4 is a diagram showing the valve opening characteristics of the expansion device according to the first embodiment.

  As shown in FIG. 1, the refrigeration cycle includes a compressor 1 that compresses refrigerant, a gas cooler 2 that cools the compressed refrigerant, an expansion device 3 that squeezes and expands the cooled refrigerant, and evaporates the expanded refrigerant. An evaporator 4 to be stored, an accumulator 5 that stores excess refrigerant in the refrigeration cycle and separates the vapor-phase refrigerant from the evaporated refrigerant and sends it to the compressor 1, and a refrigerant and accumulator 5 that flows from the gas cooler 2 to the expansion device And an internal heat exchanger 6 for exchanging heat with the refrigerant flowing to the compressor 1. In the figure, arrows indicate the flow of the refrigerant.

  In this refrigeration cycle, as shown by ABCD-A in FIG. 2, the refrigerant in the gas phase is compressed by the compressor 1 into a high-temperature and high-pressure refrigerant (A-B). The refrigerant is cooled by the gas cooler 2 (BC), and the cooled refrigerant is squeezed and expanded by the expansion device 3 to obtain a low-temperature and low-pressure refrigerant (CD), and the low-temperature and low-pressure refrigerant is supplied to the evaporator 4. Then, the operation of evaporating (DA) is performed. In the process where the expansion device 3 expands the refrigerant, when the pressure falls below the saturated liquid line SL, the refrigerant enters a gas-liquid two-phase state, and when it evaporates in the evaporator 4, it takes away latent heat of vaporization from the air in the passenger compartment. Thus, cooling is performed.

  In the refrigeration cycle using carbon dioxide as a refrigerant, an internal heat exchanger 6 for exchanging heat between the refrigerant at the outlet of the gas cooler 2 and the refrigerant at the outlet of the evaporator 4 is provided to reduce the enthalpy of the refrigerant at the inlet of the evaporator 4. Thus, generally, the refrigerating capacity is improved.

  The internal heat exchanger 6 has therein a high-pressure passage through which a high-pressure refrigerant introduced from the gas cooler 2 flows and a low-pressure passage through which a low-pressure refrigerant introduced from the accumulator 5 flows. Is provided with an expansion device 3.

  That is, as shown in FIG. 3, the internal heat exchanger 6 is formed with a high pressure passage 12 through which the refrigerant introduced from the gas cooler 2 flows out through the body 11, and the end of the high pressure passage 12. An attachment hole 13 is formed in the part, and the expansion device 3 is attached to the attachment hole 13. In a state where the expansion device 3 is mounted in the mounting hole 13, a pipe 14 communicating with the evaporator 4 is screwed to the body 11 with a fixing screw 15 at the open end of the mounting hole 13. The pipe 14 is formed to have an inner diameter slightly smaller than the outer diameter of the expansion device 3 so that the expansion device 3 does not escape from the mounting hole 13 by the high-pressure refrigerant.

  The expansion device 3 provided in the internal heat exchanger 6 has a body 21, and the body 21 is provided with a refrigerant introduction groove 22 for introducing the refrigerant of the high-pressure passage 12 in the center side portion thereof. The coolant introduction groove 22 is provided with a coolant inlet 23 toward the center of the body 21. The body 21 is also provided with a valve hole 24 in an axial direction at the lower center portion thereof, and the upstream side of the valve hole 24 communicates with the refrigerant inlet 23. Further, a valve body 25 for opening and closing the valve hole 24 is disposed downstream of the valve hole 24 so as to advance and retract in the axial direction. The valve body 25 has an outer diameter larger than the inner diameter of the valve hole 24 so that the pressure of the refrigerant introduced into the refrigerant inlet 23 is received in the valve opening direction, and the shape memory alloy spring 26 constituting the temperature sensing portion. Is biased in the valve opening direction. The spring load of the shape memory alloy spring 26 is set by adjusting the position of the cylindrical spring receiving member 27 fixed to the valve body 25 by external fitting in the axial direction with respect to the valve body 25. Further, the body 11 is provided with an orifice 28 so as to bypass the valve hole 24.

  The body 11 also holds a shaft 29 extending in the axial direction so as to be movable forward and backward in the axial direction. A lower end portion of the shaft 29 in the drawing extends through the valve hole 24 and is fixed to the valve body 25 by press-fitting. A locking portion having a large diameter for locking the spring receiving member 30 is provided at the upper end portion in the drawing. Are integrally formed, and the shaft 29 is urged in a valve closing direction by a spring 31 through a spring receiving member 30 thereof. As a result, the expansion device 3 constitutes a differential pressure control valve that opens and closes due to the differential pressure between the upstream pressure and the downstream pressure of the valve hole 24. Note that the spring 31 is set to a spring load that is bent and opens the differential pressure control valve when the pressure on the inlet side of the expansion device 3 exceeds the upper limit of the control range, for example, 13 MPa. The setting of the spring load is adjusted by the press-fit amount of the shaft 29 to the valve body 25.

  The shape memory alloy spring 26 disposed on the low pressure side of the differential pressure control valve has a spring load that reversibly changes with respect to the temperature cycle. At a temperature lower than the transformation point, the spring load is small and less than the transformation point. When the temperature is high, the spring load is increased in proportion to the temperature change. Therefore, the shape memory alloy spring 26 functions as a temperature-sensitive actuator that applies a spring load corresponding to the temperature of the refrigerant on the low-pressure side to the valve body 25 to control the pressure on the high-pressure side, and constitutes a low-temperature-side temperature sensing unit. is doing.

  In addition, an O-ring 32 for sealing is provided below the refrigerant introduction groove 22 of the body 21 in the figure, and when the expansion device 3 is attached to the attachment hole 13, the high-pressure passage 12, the pipe 14, The space between them is sealed. Similarly, an O-ring 33 is arranged between the body 11 and the pipe 14 inside the fixing screw 15 to which the pipe 14 is screwed, and the low pressure side of the expansion device 3 is sealed from the atmosphere.

  In the expansion device 3 having the above-described configuration, when the differential pressure between the pressure on the inlet side and the pressure on the outlet side is small, the spring 31 does not bend due to such differential pressure, so the differential pressure control valve is closed. At that time, the high-pressure refrigerant that has passed through the internal heat exchanger 6 flows through the orifice 28. When exiting the orifice 28, the refrigerant adiabatically expands to become a low-temperature / low-pressure refrigerant and is sent to the evaporator 4 through the pipe 14.

  Until the inlet pressure of the expansion device 3 increases and reaches 13 MPa, which is the upper limit of the control range, the throttle passage cross-sectional area of the expansion device 3 is constant determined by the cross-sectional area of the orifice 28 as shown in FIG. The throttle passage has a cross-sectional area. When the inlet pressure of the expansion device 3 reaches 13 MPa, the differential pressure control valve opens overcoming the urging force of the spring 31 in the valve closing direction. Since the diameter of the valve hole 24 of the differential pressure control valve is sufficiently larger than that of the orifice 28, the throttle passage cross-sectional area of the expansion device 3 rapidly increases when the inlet pressure exceeds the valve opening point. As a result, the inlet pressure is always kept below the pressure at the valve opening point.

  On the other hand, the shape memory alloy spring 26 arranged on the low pressure side of the differential pressure control valve senses the outlet temperature of the refrigerant that has left the expansion device 3 and opens the differential pressure control valve when the outlet temperature is high. When the outlet temperature is low, the differential pressure control valve acts in the valve closing direction. That is, when the outlet temperature is higher than the martensitic transformation temperature of the shape memory alloy spring 26, the shape memory alloy spring 26 changes to an austenite phase, and at that time, the spring load has a characteristic that changes greatly according to the temperature. is doing. Therefore, the shape memory alloy spring 26 has a spring load that changes in response to a change in the outlet temperature, and a load corresponding to the outlet temperature is applied to the valve body 25 in the valve opening direction.

  For example, when the outlet temperature of the expansion device 3 is 10 ° C., the pressure on the low pressure side is about 4.6 MPa according to the Mollier diagram of FIG. For this reason, the shape memory alloy spring 26 is set so that a spring load corresponding to the pressure is generated when the temperature is 10 ° C. At this time, the differential pressure control valve is adjusted so that the spring setting is opened with a differential pressure of 8.4 MPa. As a result, the inlet pressure of the expansion device 3 was uniquely specified to 13 MPa, which is a value obtained by adding 8.4 MPa, which is a differential pressure difference relative to 4.6 MPa, which is the pressure corresponding to the outlet temperature. become. The pressure change of the refrigeration cycle at this time is A-B-C-D-A.

  Here, if the outlet temperature of the expansion device 3 rises to 20 ° C., the shape memory alloy spring 26 increases its spring load and acts on the differential pressure control valve in the valve opening direction. The differential pressure at which the valve opens changes from FIG. 2 to about 7.15 MPa. Since the refrigerant pressure when the outlet temperature is 20 ° C. is about 5.85 MPa, the inlet pressure of the expansion device 3 is set to 13 MPa. The pressure change of the refrigeration cycle at this time is A'-B-C-D'-A '.

  As described above, when a high refrigeration capacity is required and the compressor 1 is operating at its maximum discharge capacity, the expansion device 3 senses the differential pressure between the inlet pressure and the outlet pressure and the outlet temperature. By performing temperature correction so that the differential pressure is added to the pressure corresponding to the outlet temperature, the inlet pressure operates as if it is controlled by an absolute pressure. Moreover, if the inlet pressure exceeds 13 MPa, the differential pressure control valve simply functions as a pressure relief valve and opens rapidly, so that the inlet pressure is maintained at 13 MPa. As a result, the inlet pressure does not become abnormally high.

  FIG. 5 is a central longitudinal sectional view showing the configuration of the expansion device according to the second embodiment. In FIG. 5, components having the same or equivalent functions as those shown in FIG. 3 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion device 3a according to the second embodiment can efficiently operate the refrigeration cycle by sensing the temperature of the refrigerant at the inlet of the expansion device 3, as compared with the expansion device 3 according to the first embodiment. It differs in the point comprised as follows.

  That is, in the expansion device 3a, a cylindrical cylinder is integrally formed in the upper part of the body 21 in the figure, and when the inlet pressure exceeds 13 MPa, it is bent to open the differential pressure control valve. A spring 31 acting as described above and a shape memory alloy spring 41 for sensing the inlet temperature are accommodated in series, and the shape memory alloy spring 41 includes a bias spring for adjusting the spring characteristics. 42 are arranged in parallel. That is, the shape memory alloy spring 41 and the biasing spring 42 are loosely coupled with a spring receiving member 30 that is locked to a locking portion formed integrally with the upper end of the shaft 29 in the figure, and the shaft 29 is loosely passed through the center. The spring 31 is disposed between the spring receiving member 43 and the bottom of the cylindrical cylinder. The spring receiving member 43 is restricted from moving upward in the drawing by an adjusting member 44 press-fitted into the cylinder, and is restricted from moving downward in the drawing by a stopper 45 fixed to the shaft 29.

  The adjusting member 44 is press-fitted into the cylinder up to a position where the adjusting member 44 comes into contact with the extended unloaded spring 31 via the spring receiving member 43. Thus, when the inlet pressure is 13 MPa or less, even if a force in the valve opening direction is applied to the spring 31 via the shaft 29, the shape memory alloy spring 41, and the biasing spring 42, the spring 31 does not bend. When the inlet pressure exceeds 13 MPa, it bends and opens the differential pressure control valve quickly.

  On the other hand, the shape memory alloy spring 41 senses the inlet temperature. When the inlet temperature is low, the shape memory alloy spring 41 has a small spring load, so the combined load of the shape memory alloy spring 41 and the spring 42 is small, and the set differential pressure at which the differential pressure control valve opens is set to a small value. Will be. As the inlet temperature increases, the combined load of the shape memory alloy spring 41 and the spring 42 increases. Therefore, the set differential pressure is also set to a large value, and the change in the spring load with respect to the temperature change of the shape memory alloy spring 41 is saturated. Above the predetermined temperature, the shape memory alloy spring 41 is stretched between the spring receiving member 30 and the spring receiving member 43.

  According to the expansion device 3a, when the inlet temperature is low, the spring load of the shape memory alloy spring 41 and the biasing spring 42 acting in the valve closing direction is small. It opens to a minute opening corresponding to the orifice 28 by a pressure difference from the pressure, the refrigerant flows, and the refrigerant adiabatically expands. At this time, similarly to the expansion device 3 according to the first embodiment, the pressure at the inlet of the expansion device 3a is controlled to a pressure determined by the differential pressure before and after the differential pressure control valve and the pressure corresponding to the outlet temperature. ing.

  On the other hand, the temperature of the refrigerant at the inlet of the expansion device 3a is sensed by the shape memory alloy spring 41, and the predetermined value of the differential pressure corrected by the shape memory alloy spring 26 is shifted according to the change in the inlet temperature. I have to. Thereby, the temperature and pressure of the refrigerant at the inlet of the expansion device 3a, that is, the temperature and pressure at the point C in FIG. Control can be performed along the approximate control line CL.

  Of course, also in this expansion device 3a, when the inlet pressure rises and exceeds 13 MPa, the spring 31 is bent and the differential pressure control valve is suddenly opened. The pressure does not rise above that.

  FIG. 6 is a central longitudinal sectional view showing the configuration of the expansion device according to the third embodiment. In FIG. 6, components having the same or equivalent functions as those shown in FIG. 5 are given the same reference numerals, and detailed descriptions thereof are omitted.

  In the expansion device 3b according to the third embodiment, the positional relationship between the spring 31, the shape memory alloy spring 41, and the spring 42 is reversed as compared with the expansion device 3a according to the second embodiment. It is different in point.

  According to this expansion device 3b, when the inlet temperature is low, the shape memory alloy spring 41 has a small spring load, and the valve opening force of the valve body 25 due to the differential pressure between the inlet pressure and the outlet pressure is the shaft 29, the spring receiver. Since it is bent by being transmitted through the member 30, the spring 31 and the spring receiving member 43, the differential pressure control valve is slightly opened. At this time, the pressure at the inlet of the expansion device 3b is determined by the differential pressure before and after the differential pressure control valve and the pressure corresponding to the outlet temperature, as in the expansion devices 3 and 3a according to the first and second embodiments. The pressure is controlled to be determined. The shape memory alloy spring 41 provided at the inlet of the expansion device 3a controls the temperature of the refrigerant at the inlet of the expansion device 3a along a control line CL that approximates the optimal control line. With respect to the inlet pressure of the expansion device 3a, when the spring 31 senses a pressure exceeding 13 MPa, the differential pressure control valve is suddenly opened.

  FIG. 7 is a central longitudinal sectional view showing the configuration of the expansion device according to the fourth embodiment. In FIG. 7, components having the same or equivalent functions as those shown in FIG. 5 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion device 3c according to the fourth embodiment has the same basic configuration as the expansion device 3a according to the second embodiment, but the high pressure sensing spring 31 and the shape memory alloy. The difference is that the spring 41 and the spring 42 are configured to be easily assembled and adjusted.

  That is, in the expansion device 3c, the spring receiving member 43 having the shaft 29 loosely passed through the center is integrally formed with the cylindrical body containing the shape memory alloy spring 41 and the spring 42, and the cylindrical body A stopper 45 for adjusting the spring load of the shape memory alloy spring 41 and the spring 42 is press-fitted through the spring receiving member 30. The spring receiving member 43 is placed on the upper part of the spring 31 in the figure, and an adjustment member 44 having a cylindrical shape is fixed to the body 21 so as to accommodate them.

  When assembling the expansion device 3c, first, the shape memory alloy spring 41 and the spring 42 are assembled while adjusting the spring load in advance. That is, the shape memory alloy spring 41, the spring 42, and the spring receiving member 30 are placed in this order in the cylindrical body of the spring receiving member 43, and the stopper 45 is press-fitted into the cylindrical body to a predetermined position. The spring loads of the memory alloy spring 41 and the spring 42 are adjusted to configure the high temperature side temperature sensing part. Then, the adjusted high temperature side temperature sensing part is placed on the spring 31 disposed in the upper space of the body 21 in the figure, and the adjustment of the cylindrical shape having a locking part in which the upper part of the figure is bent inward from above. With the member 44 covered, with the upper part of the body 21 being partially press-fitted into the lower part of the figure, the adjustment member 44 is further moved downward in the figure until the locking part abuts on the upper end of the spring receiving member 43 in the figure. The adjustment member 44 is fixed to the body 21 by pushing down. Furthermore, the spring load of the spring 31 can be adjusted by further pushing down the adjusting member 44 downward as needed. Finally, the shaft 29 is inserted from above, and the differential pressure control valve has a predetermined minimum opening degree by the shape memory alloy spring 26 to the valve body 25 in which the spring load of the shape memory alloy spring 26 is adjusted. Thus, the expansion device 3c is assembled by press-fitting a predetermined amount.

Since the basic configuration of the expansion device 3c is the same as that of the expansion device 3a according to the second embodiment, the operation thereof is the same as that of the expansion device 3a.
FIG. 8 is a central longitudinal sectional view showing the configuration of the expansion device according to the fifth embodiment, and FIG. 9 is a view showing the valve opening characteristics of the expansion device according to the fifth embodiment. 8, components having the same or equivalent functions as the components shown in FIG. 7 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion device 3d according to the fifth embodiment is different from the high temperature side temperature sensing unit including the shape memory alloy spring 41 and the biasing spring 42 in the expansion device 3c according to the fourth embodiment. The difference is that a spring 42a for opening the pressure control valve with a differential pressure lower than 13 MPa is provided.

  According to the expansion device 3d having this configuration, as shown in FIG. 9, the expansion device 3d has a characteristic of having two valve opening points that are opened in response to a change in the refrigerant inlet pressure on the upstream side. That is, the expansion device 3d is at a predetermined minimum opening when the inlet pressure is low and has a constant throttle passage cross-sectional area. When the inlet pressure becomes high and the inlet pressure exceeds a predetermined set value set by the spring 42a, the spring 42a is bent and the differential pressure control valve is opened. As the inlet pressure increases, the throttle passage cross-sectional area increases. Increases proportionally. Furthermore, when the inlet pressure increases and exceeds 13 MPa set by the spring 31, the differential pressure control valve opens rapidly. Thereby, since an inlet pressure falls, it does not become higher than 13 MPa.

  FIG. 10 is a central longitudinal sectional view showing the configuration of the expansion device according to the sixth embodiment. 10, components having the same or equivalent functions as the components shown in FIG. 5 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion device 3e according to the sixth embodiment has the same basic configuration as that of the expansion device 3a according to the second embodiment, but the high-temperature side temperature sensing unit is an internal heat exchanger in the expansion device 3a. The difference is that the outlet temperature of the internal heat exchanger 6, that is, the outlet temperature of the gas cooler 2 is detected while the outlet temperature of the gas generator 6 is detected.

  In the internal heat exchanger 6, in the high-pressure passage 12 formed in the body 11, the refrigerant inlet passage 46 into which the high-pressure refrigerant is introduced from the gas cooler 2 is formed so as to pass in the vicinity of the mounting hole 13 to which the expansion device 3e is attached. Has been. The attachment hole 13 is formed so as to penetrate to the refrigerant inlet passage 46, and when the expansion device 3 e is attached to the attachment hole 13, the high temperature side temperature sensing portion is positioned in the refrigerant inlet passage 46. ing. In the expansion device 3 e, an O-ring 47 is provided around the body 21 so that the refrigerant in the refrigerant inlet passage 46 does not leak into the refrigerant inlet 23 in a state where the expansion device 3 e is mounted in the attachment hole 13.

  Also in the configuration of the expansion device 3e, the operation is the same as that of the expansion device 3a except that the high temperature side temperature sensing unit senses the temperature of the outlet of the gas cooler 2 in the refrigerant inlet passage 46 of the internal heat exchanger 6. .

  FIG. 11 is a central longitudinal sectional view showing the configuration of the expansion device according to the seventh embodiment. In FIG. 11, components having the same or equivalent functions as those shown in FIG. 10 are given the same reference numerals, and detailed descriptions thereof are omitted.

  Compared with the expansion device 3e according to the sixth embodiment, the expansion device 3f according to the seventh embodiment has a simplified configuration of the high temperature side temperature sensing unit that senses the temperature of the outlet of the gas cooler 2. It is different in point. That is, the expansion device 3f has a configuration in which the stopper 45 included in the high temperature side temperature sensing portion of the expansion device 3e is eliminated, and the shape memory alloy spring 41 and the spring 42 and the high pressure sensing spring 31 are arranged in series. To be. As a result, when the temperature and pressure at the outlet of the gas cooler 2 are high, the shape memory alloy spring 41 acts in a direction to increase the spring load of the high pressure sensing spring 31, so that the differential pressure control valve is open to the pressure. This characteristic does not show an abrupt change, but becomes a somewhat smooth characteristic.

  FIG. 12 is a central longitudinal sectional view showing the configuration of the expansion device according to the eighth embodiment. 12, constituent elements having the same or equivalent functions as those shown in FIG. 3 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion device 3g according to the eighth embodiment is arranged downstream from the expansion device 3 according to the first embodiment, whereas the high-pressure sensing spring 31 is disposed upstream. Is different.

  That is, the expansion device 3g has a valve body 25 disposed downstream of a valve hole 24 formed in the body 21, and is integrally formed with the valve body and is accommodated in the body 21 so as to be movable back and forth in the axial direction. Further, the high pressure sensing spring 31 is urged in the valve closing direction with respect to the piston 51, and the shape memory alloy spring 26 of the low temperature side temperature sensing unit is urged in the valve opening direction. The spring load for the high pressure sensing spring 31 is adjusted by an adjusting screw 52 screwed to the body 21. As a result, the predetermined value of the differential pressure when the differential pressure control valve opens when the spring 31 is bent by receiving the differential pressure between the upstream refrigerant pressure and the downstream refrigerant pressure is the shape memory alloy spring 26. Therefore, the temperature is corrected by the outlet temperature of the downstream refrigerant sensed, and when the upstream refrigerant pressure is high, the pressure is always maintained at 13 MPa set by the spring 31.

  In addition, the expansion device 3g is provided with an orifice 28 in the valve body 25 for flowing a minimum amount of refrigerant when the differential pressure control valve is fully closed, and a strainer that removes foreign matters in the refrigerant upstream of the valve hole. 53 is provided.

  FIG. 13 is a central longitudinal sectional view showing the configuration of the expansion device according to the ninth embodiment. In FIG. 13, components having the same or equivalent functions as those shown in FIG. 12 are given the same reference numerals and detailed description thereof is omitted.

  The expansion device 3h according to the ninth embodiment includes a second differential pressure control valve in addition to the differential pressure control valve (hereinafter referred to as the first differential pressure control valve) of the expansion device 3g according to the eighth embodiment. The difference is that two differential pressure control valves with different valve opening points are configured to function in parallel.

  That is, in the expansion device 3h, the orifice 28 provided in the valve body 25 of the first differential pressure control valve serves as the valve hole of the second differential pressure control valve, and the valve is provided downstream so as to open and close the valve hole. A body 61 is disposed, and a piston 62 formed integrally with the valve body is accommodated in the piston 51 of the first differential pressure control valve so as to be movable back and forth in the axial direction. The piston 62 is urged in the valve closing direction by a spring 63, and the spring load of the spring 63 is adjusted by an adjustment screw 64 screwed to the piston 51. In addition, the valve body 61 of the second differential pressure control valve is also provided with an orifice 65 for allowing a minimum flow rate of refrigerant to flow when the first and second differential pressure control valves are fully closed.

  Such an expansion device 3h has a characteristic as shown in FIG. 9 having two valve opening points that are opened in response to a change in the inlet pressure of the refrigerant on the upstream side. That is, in this expansion device 3h, the shape memory alloy spring 26 senses the outlet temperature of the downstream refrigerant and corrects the predetermined value of the differential pressure when the first differential pressure control valve opens. The inlet pressure is detected as a pseudo absolute pressure. Here, when the inlet pressure is low, the throttle passage cross-sectional area of the expansion device 3h has a constant throttle passage cross-sectional area determined by the cross-sectional area of the orifice 65 of the second differential pressure control valve. When the inlet pressure becomes high and the differential pressure between the upstream inlet pressure and the downstream outlet pressure exceeds the pressure set by the spring 63, the second differential pressure control valve opens, As the pressure increases, the throttle passage cross-sectional area increases proportionally. Thereafter, when the inlet pressure reaches 13 MPa, the first differential pressure control valve starts to open. Further, when the inlet pressure becomes higher and exceeds 13 MPa set by the spring 31, the first differential pressure control valve is suddenly opened. Thereby, since an inlet pressure falls, it does not become higher than 13 MPa.

  In the first to ninth embodiments described above, the low temperature side temperature sensing unit corrects the predetermined value of the valve opening differential pressure of the differential pressure control valve in accordance with the temperature change of the refrigerant on the downstream side of the differential pressure control valve. It is configured. However, the predetermined value of the valve opening differential pressure can be corrected not only according to the temperature change of the refrigerant downstream of the differential pressure control valve but also according to the pressure change of the refrigerant downstream of the differential pressure control valve. This is because the refrigerant is in a saturated liquid state at the outlet of the expansion device, and in this saturated liquid state, the temperature and pressure change as indicated by DA or D′-A ′ in the Mollier diagram of FIG. This is because the pressure is determined if the temperature is determined. As described above, in the evaporator 4 on the outlet side of the expansion device, the evaporation pressure is constant, and the temperature and the pressure are in a primary relationship. Therefore, sensing the pressure at the expansion device outlet detects the temperature at the expansion device outlet. It can be regarded as equivalent to sensing. As a result, instead of the low temperature side temperature sensing unit, the low temperature side pressure sensing unit senses the pressure at the outlet of the expansion device, and the differential pressure control valve opening differential pressure is detected according to the refrigerant pressure change downstream of the differential pressure control valve. Also, the same function as that of the expansion devices 3 to 3h of the first to ninth embodiments can be provided by correcting the predetermined value. Hereinafter, the detail of the structure provided with such a low temperature side pressure sensing part is demonstrated.

  FIG. 14 is a central longitudinal sectional view showing the configuration of the expansion device according to the tenth embodiment. In FIG. 14, components having the same or equivalent functions as those shown in FIG. 12 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The expansion device 3i according to the tenth embodiment includes a low-temperature side pressure-sensitive portion instead of the shape memory alloy spring 26 that is the low-temperature-side temperature detection portion of the expansion device 3g according to the eighth embodiment. . That is, in the expansion device 3 i, the power element 71 is screwed onto the cylindrical portion opening end of the body 21. When the power element 71 senses a high pressure, the power element 71 acts in a direction to reduce the spring load of the high pressure sensing spring 31 that sets the valve opening differential pressure of the differential pressure control valve, and the valve opening differential pressure is predetermined. It functions as a pressure-sensitive actuator that corrects in the direction of decreasing the value.

  The power element 71 has a diaphragm 74 made of a thin metal plate sandwiched between an outer housing 72 having a center projecting outward and an inner housing 73 having a hub that is open at the center and coupled to the body 21. The disc spring 75, the spring 76, and the spring receiving member 77 are accommodated in a sealed space formed by the outer housing 72 and the diaphragm 74 formed by welding all the parts together in a high-pressure gas or vacuum atmosphere. Has been. The load adjustment of the disc spring 75 is adjusted by combining a plurality of disc springs (three in the illustrated example) having appropriate spring loads, and the spring load of the spring 76 is plastically deformed with the end face of the outer housing 72 inward. Thus, the spring receiving member 77 is adjusted by changing the position of the spring receiving member 77 in the direction in which the spring 76 is compressed. A displacement transmitting member 78 that transmits the displacement of the diaphragm 74 to the spring 31 is disposed on the opposite side of the diaphragm 74 from the side where the disc spring 75 is disposed. A stopper 79 with a step is formed inside the inner housing 73 and restricts the displacement transmitting member 78 from moving in the direction of increasing the spring load of the spring 31. Thus, when the pressure on the downstream side of the differential pressure control valve is operating at a low level, the differential pressure control valve is prohibited from correcting the predetermined value of the differential pressure.

  In this embodiment, a part of the thread of the body 21 screwed to the power element 71 is cut so that the refrigerant pressure on the downstream side of the differential pressure control valve is easily transmitted to the diaphragm 74. However, since the screwed portion between the power element 71 and the body 21 is not completely joined in an airtight state, the cut portion is not always necessary.

  In the expansion device 3i configured as described above, when the differential pressure between the pressure on the inlet side and the pressure on the outlet side is small, the spring 31 does not bend due to such a differential pressure, so the differential pressure control valve is closed. At that time, the high-pressure refrigerant that has passed through the internal heat exchanger 6 flows through the orifice 28. When exiting the orifice 28, the refrigerant adiabatically expands to become a low-temperature / low-pressure refrigerant and is sent to the evaporator 4 through the pipe 14.

  Until the inlet pressure of the expansion device 3i increases and reaches 13 MPa, which is the upper limit of the control range, the expansion passage cross-sectional area of the expansion device 3i has a constant expansion passage cross-sectional area determined by the cross-sectional area of the orifice 28. ing. When the inlet pressure of the expansion device 3i reaches 13 MPa, the differential pressure control valve overcomes the urging force in the valve closing direction by the spring 31 and opens. Since the diameter of the valve hole 24 of the differential pressure control valve is sufficiently larger than that of the orifice 28, when the inlet pressure exceeds the valve opening point, the throttle passage sectional area of the expansion device 3i increases rapidly. As a result, the inlet pressure is always kept below the pressure at the valve opening point.

  On the other hand, the power element 71 disposed on the low pressure side of the differential pressure control valve senses the outlet pressure of the refrigerant exiting the expansion device 3i, and receives the pressure via the diaphragm 74 when the outlet pressure is high. When the outlet pressure is low, the central part of the disc spring 75 is on the outer side (upper side in the figure). The shape changes to a bulged shape and acts to increase the valve opening differential pressure. That is, the power element 71 corrects the predetermined value of the valve opening differential pressure by applying a load corresponding to the outlet pressure of the differential pressure control valve to the valve body 25 in the valve opening direction.

  As a result, when high refrigeration capacity is required and the compressor 1 is operating at its maximum discharge capacity, the expansion device 3i senses the differential pressure between the inlet pressure and the outlet pressure and the outlet pressure. By correcting the pressure so that the pressure is added to the outlet pressure, it operates as if the inlet pressure is controlled by the absolute pressure. Moreover, if the inlet pressure exceeds 13 MPa, the differential pressure control valve simply functions as a pressure relief valve and opens rapidly, so that the inlet pressure is maintained at 13 MPa. As a result, the inlet pressure does not become abnormally high.

  The power element 71 can accurately detect the outlet pressure of the expansion device 3i when the inside of the room in which the disc spring 75 is housed is vacuum, so that the inlet pressure of the expansion device 3i can be accurately determined. It is possible to monitor with absolute pressure. In addition, when high pressure gas is sealed in the room in which the disc spring 75 is accommodated, the high pressure gas acts like an air spring, so that a disc spring 75 having a small spring load can be adopted. it can. In this case, when the expansion device 3i is placed as a component, the stopper 79 restricts the movement of the displacement transmitting member 78 so that the high pressure gas does not excessively expand the diaphragm 74 toward the differential pressure control valve. is doing.

  FIG. 15 is a central longitudinal sectional view showing the configuration of the expansion device according to the eleventh embodiment. In FIG. 15, components having the same or equivalent functions as those shown in FIG. 13 are given the same reference numerals, and detailed descriptions thereof are omitted.

  In the expansion device 3j according to the eleventh embodiment, the shape memory alloy spring 26 of the expansion device 3h of the ninth embodiment shown in FIG. 13 is changed to a low-temperature side pressure sensitive part shown in FIG. . That is, when the expansion device 3j senses a high pressure, the power element 71 that corrects the first differential pressure control valve in the direction to reduce the spring load of the spring 35 that has urged the first differential pressure control valve in the valve closing direction is provided on the body 21. It is screwed to the cylindrical part. In addition, the orifice 28 of the valve body 25 of the first differential pressure control valve is provided with an orifice 65 for flowing a minimum amount of refrigerant when the first and second differential pressure control valves are fully closed.

  According to such an expansion device 3j, the power element 71 senses the outlet pressure of the refrigerant on the downstream side and corrects the predetermined value of the differential pressure when the first differential pressure control valve opens. The inlet pressure is detected as a pseudo absolute pressure. Here, when the inlet pressure is low, the throttle passage cross-sectional area of the expansion device 3j has a constant throttle passage cross-sectional area determined by the cross-sectional area of the orifice 65 of the first differential pressure control valve. When the inlet pressure becomes high and the differential pressure between the upstream inlet pressure and the downstream outlet pressure exceeds the pressure set by the spring 63, the second differential pressure control valve opens, As the pressure increases, the throttle passage cross-sectional area increases proportionally. Thereafter, when the inlet pressure reaches 13 MPa, the first differential pressure control valve starts to open. Further, when the inlet pressure becomes higher and exceeds 13 MPa set by the spring 31, the first differential pressure control valve is suddenly opened. As a result, the throttle passage cross-sectional area rapidly increases and the inlet pressure decreases, so that the inlet pressure does not exceed 13 MPa.

It is a system diagram which shows the refrigerating cycle to which the expansion apparatus which concerns on 1st Embodiment is applied. It is a Mollier diagram of carbon dioxide. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 1st Embodiment. It is a figure which shows the valve opening characteristic of the expansion apparatus which concerns on 1st Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 2nd Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 3rd Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 4th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 5th Embodiment. It is a figure which shows the valve opening characteristic of the expansion apparatus which concerns on 5th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 6th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 7th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 8th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 9th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 10th Embodiment. It is a center longitudinal cross-sectional view which shows the structure of the expansion apparatus which concerns on 11th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Gas cooler 3, 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j Expansion device 4 Evaporator 5 Accumulator 6 Internal heat exchanger 11 Body 12 High pressure passage 13 Mounting hole 14 Piping 15 Fixing screw 21 Body 22 Refrigerant introduction groove 23 Refrigerant inlet 24 Valve hole 25 Valve body 26 Shape memory alloy spring 27 Spring receiving member 28 Orifice 29 Shaft 30 Spring receiving member 31 Spring 32, 33 O-ring 41 Shape memory alloy spring 42, 42a Spring 43 Spring receiving Member 44 Adjustment member 45 Stopper 46 Refrigerant inlet passage 47 O-ring 51 Piston 52 Adjustment screw 53 Strainer 61 Valve element 62 Piston 63 Spring 64 Adjustment screw 65 Orifice 71 Power element 72 Outer housing 73 Inner housing Ring 74 Diaphragm 75 disc spring 76 spring 77 spring receiving member 78 displacement-transmitting member 79 a stopper

Claims (21)

In the expansion device for expanding the refrigerant circulating in the refrigeration cycle,
A differential pressure control valve that opens due to a differential pressure between the upstream pressure and the downstream pressure of the refrigerant;
A spring that is arranged to urge the differential pressure control valve in a valve closing direction, and that opens the differential pressure control valve when the differential pressure is greater than or equal to a predetermined value;
An actuator that is arranged on the downstream side and corrects the predetermined value of the differential pressure that the differential pressure control valve opens in response to a change in temperature or pressure of the refrigerant on the downstream side;
An inflating device comprising:   The actuator is disposed on the downstream side so as to urge the valve body of the differential pressure control valve in the valve opening direction, and corrects the predetermined value to be reduced in accordance with the temperature rise of the refrigerant on the downstream side. The expansion device according to claim 1, wherein the expansion device is a temperature sensing unit.   The low temperature side temperature sensing unit has a load for correcting the predetermined value of the differential pressure that is opened by the differential pressure control valve in accordance with a temperature change of the refrigerant on the downstream side within a predetermined temperature range. The expansion device according to claim 2, wherein the expansion device is a shape memory alloy spring that changes.   2. The expansion device according to claim 1, further comprising an orifice that bypasses the differential pressure control valve in parallel with a valve hole of the differential pressure control valve.   A shaft disposed through the valve hole and having one end fixed to the valve body disposed on the downstream side of the valve hole and transmitting a force in the opening / closing direction of the valve body due to the differential pressure; The other end of the refrigerant is locked to the spring disposed upstream of the valve hole in a direction of bending as the differential pressure increases, and the spring has a high temperature of the refrigerant on the downstream side through the shaft. The expansion device according to claim 2, wherein a temperature is corrected by the low temperature side temperature sensing unit by applying a load in a direction in which the temperature is bent.   The predetermined pressure is arranged in series with the spring so as to urge the differential pressure control valve upstream in the valve closing direction, and is corrected by the low temperature side temperature sensing unit according to the temperature change of the refrigerant on the upstream side. The expansion device according to claim 5, further comprising a high temperature side temperature sensing unit that shifts the value.   The expansion device according to claim 6, wherein the high temperature side temperature sensing unit is a shape memory alloy spring in which a spring load changes according to a temperature change of the refrigerant on the upstream side.   The expansion device according to claim 7, wherein a biasing spring is disposed in parallel with the shape memory alloy spring.   A first spring receiving member disposed between the spring and the high temperature side temperature sensing unit; and a stopper fixed to the shaft, wherein the high temperature side temperature sensing unit detects a temperature equal to or higher than the predetermined value. 8. The expansion device according to claim 7, wherein when the first spring receiving member is pressed, an increase in spring load of the first spring receiving member is restricted by the stopper.   The expansion device according to claim 9, wherein the shape memory alloy spring is housed in a cylindrical body having a bottom with a spring load adjusted via a second spring receiving member.   A shaft disposed through the valve hole and the cylindrical body and having one end fixed to the valve body and transmitting a force in the valve opening direction due to the differential pressure of the valve body; and the other end of the shaft 11. The expansion device according to claim 10, wherein the shape memory alloy spring is locked to the second spring receiving member in the cylindrical body in a direction in which the shape memory alloy spring bends as the differential pressure increases.   The differential pressure control valve that opens when the differential pressure becomes greater than the predetermined value is set to a predetermined minute opening when the differential pressure is equal to or less than the predetermined value. The expansion device according to claim 6.   The differential pressure control valve is arranged in series with the spring so as to urge the differential pressure control valve upstream in the valve closing direction, and gradually opens the differential pressure control valve from a set differential pressure smaller than the predetermined value. 6. The expansion device according to claim 5, further comprising a spring.   The differential pressure control valve is disposed so as to function in parallel with the differential pressure control valve, and the spring includes another differential pressure control valve that opens with a differential pressure smaller than the predetermined value that opens the differential pressure control valve. The inflator according to claim 2.   The actuator is arranged to receive, via the spring, the valve body of the differential pressure control valve when moving in the valve opening direction due to the differential pressure on the downstream side, and according to the pressure increase of the refrigerant on the downstream side 2. The expansion device according to claim 1, wherein the expansion device is a low-temperature side pressure-sensitive part that acts in a direction to reduce a spring load of the spring and corrects the predetermined value to be reduced.   The low-temperature side pressure-sensitive portion sandwiches the diaphragm in an airtight state between a first housing having a center projecting outward and a second housing having a center opened, and the diaphragm receives the pressure on the downstream side to receive the difference. 16. The expansion device according to claim 15, wherein the expansion element is a power element in which a disc spring that supports displacement from the inside of the pressure control valve in the valve opening direction is provided in the first housing.   The expansion device according to claim 16, wherein the power element evacuates a chamber in which the disc spring is accommodated.   17. The power element is characterized in that a chamber in which the disc spring is accommodated is filled with gas, and a stopper for restricting the expansion of the diaphragm is provided in the second housing. Inflating device.   The differential pressure control valve is disposed so as to function in parallel with the differential pressure control valve, and the spring includes another differential pressure control valve that opens with a differential pressure smaller than the predetermined value that opens the differential pressure control valve. 16. An inflator according to claim 15, characterized in that In the expansion device for expanding the refrigerant circulating in the refrigeration cycle,
An orifice disposed between the refrigerant inlet and the refrigerant outlet;
A differential pressure control valve disposed in parallel with the orifice and opened by a differential pressure between the pressure at the refrigerant inlet and the pressure at the refrigerant outlet;
A spring that is arranged to urge the differential pressure control valve in a valve closing direction, and that opens the differential pressure control valve when the differential pressure is greater than or equal to a predetermined value;
An upstream pressure when the differential pressure control valve is opened by correcting the set differential pressure by changing the load of the spring according to a change in temperature or pressure of the refrigerant outlet, arranged at the refrigerant outlet Set differential pressure correction means to prevent the change,
An inflating device comprising:   21. The expansion device according to claim 20, wherein the set differential pressure correction unit corrects the set differential pressure in a direction to decrease as the temperature or pressure at the refrigerant outlet increases.

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