JP2017201223A - Refrigerating cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the design of a bypass mechanism for a refrigerating cycle device having a bypass mechanism for bypassing a part of refrigerant flowing from an expansion valve toward an evaporator and directing it to a temperature sensitive portion of the expansion valve.SOLUTION: A bypass mechanism 6 has a throttling passage 633a formed therein which connects between pressure chambers P1, P2 and serves as a resistance to refrigerant circulation between the pressure chambers P1, P2, and a piston 63 can move between the pressure chamber P1 and the pressure chamber P2. When the pressure chamber P1, P2 are at an equalized pressure, the piston 63 is positioned at a closed position, a return passage 72 and the pressure chamber P1 are connected with each other, and a forward passage 71 is partitioned off from the pressure chamber P1. When the refrigerant pressure of the pressure chamber P1 is higher than the refrigerant pressure of the pressure chamber P2, the piston 63 is positioned at an open position, the forward passage 71 and the pressure chamber 1 are connected with each other through a forward passage-side communication passage 75, and the return passage 72 and the pressure chamber P1 are connected with each other through a return passage-side communication passage 74 to open a bypass route BP.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a refrigeration cycle apparatus.

  Conventionally, when a vehicle air conditioner is started in a high-temperature environment because the mounted vehicle is left in the sun, etc., the throttle opening of the temperature expansion valve increases rapidly immediately after the start, and the refrigerant flow rate increases. In some cases, the refrigerant passing noise in the evaporator or the like becomes loud.

  Non-Patent Document 1 discloses a refrigeration cycle apparatus that bypasses a part of the refrigerant from the expansion valve to the evaporator and leads to the temperature sensing part of the expansion valve for a short time immediately after startup in order to reduce the refrigerant passing sound. Are known. The refrigeration cycle apparatus of Non-Patent Document 1 enables the superheat control of the expansion valve at an early stage by quickly cooling the temperature sensing part of the temperature type expansion valve, thereby suppressing the refrigerant flow and reducing the refrigerant passing sound. To do.

Invention Promotion Association Public Technical Bulletin No. 2014-503284

  However, since the refrigeration cycle apparatus of Non-Patent Document 1 uses a shape memory alloy spring to drive the valve body that opens and closes the bypass path, the design of the shape memory alloy spring is not easy.

  In view of the above points, the present invention facilitates the design of a bypass mechanism in a refrigeration cycle apparatus including a bypass mechanism for bypassing a part of the refrigerant from the expansion valve to the evaporator and guiding the refrigerant to the temperature sensing part of the expansion valve. With the goal.

In order to achieve the above object, the invention described in claim 1
A compressor (2) for sucking and compressing and discharging a refrigerant;
A condenser (3) for condensing the refrigerant discharged from the compressor;
An expansion valve (4) for adjusting the throttle opening degree of the decompression flow path (411) through which the refrigerant flowing out of the condenser passes;
An evaporator (5) for evaporating the refrigerant flowing out of the expansion valve;
A bypass mechanism (6) for bypassing the evaporator and flowing the refrigerant,
The expansion valve includes a temperature sensing section (43, 44) whose temperature changes according to the temperature of the refrigerant in the temperature detection flow path (412) on the downstream side of the refrigerant flow of the evaporator and on the upstream side of the refrigerant flow of the compressor, A valve body (42) that moves according to the temperature of the temperature sensing part,
The valve body moves so that the throttle opening increases as the temperature of the temperature sensing unit increases, and the lower the refrigerant pressure on the refrigerant flow downstream side of the valve body and the refrigerant flow upstream side of the compressor, Move the valve body to increase the throttle opening,
The bypass mechanism is movable between the first pressure chamber (P1) and the second pressure chamber (P2) under the pressure of the first pressure chamber (P1) and the pressure of the second pressure chamber (P2). A piston (63), a biasing member (62) for biasing the piston toward the second pressure chamber, and the first pressure chamber and the first pressure chamber. And a throttle portion (66) that provides resistance to the flow of refrigerant between the second pressure chamber and the second pressure chamber,
When the refrigerant pressure in the first pressure chamber and the refrigerant pressure in the second pressure chamber are equalized, the piston is located in the closed position;
When the piston is located at the closed position, the return passage communicates with the first pressure chamber, and the forward passage is separated from the first pressure chamber by the piston,
When the refrigerant pressure in the second pressure chamber is higher than the refrigerant pressure in the first pressure chamber, the piston is located in the open position;
When the piston is located at the open position, the forward passage and the first pressure chamber communicate with each other, and the return passage and the first pressure chamber communicate with each other, thereby bypassing the evaporator from the forward passage. And a bypass path (BP) flowing through the first pressure chamber to the return path is opened.

  It is assumed that such a refrigeration cycle is activated in a high temperature environment and when the piston is in the closed position. Then, the compressor starts to suck the refrigerant. Thereby, the pressure of the refrigerant on the downstream side of the refrigerant flow of the valve body and on the upstream side of the refrigerant flow of the compressor suddenly decreases. However, because of the high temperature environment, the temperature of the temperature sensitive part does not decrease immediately. Therefore, the valve body moves and the throttle opening of the expansion valve increases rapidly.

  Then, the refrigerant having a large flow rate flows downstream of the refrigerant flow of the expansion valve. In this way, the expansion valve increases immediately after the start of the refrigeration cycle apparatus, and an excessive amount of refrigerant passes through the evaporator, so that the volume of the refrigerant passing sound increases in the evaporator or the pipes before and after the evaporator.

  Further, at the same time as the refrigerant pressure on the downstream side of the refrigerant flow of the evaporator decreases, the refrigerant pressure also starts to decrease in the first pressure chamber communicating with the return passage. However, since the throttle portion exists between the first pressure chamber and the second pressure chamber, the decrease in the refrigerant pressure in the second pressure chamber is delayed from the decrease in the refrigerant pressure in the first pressure chamber. That is, the refrigerant pressure in the second pressure chamber is higher than the refrigerant pressure in the first pressure chamber.

  Therefore, the position of the piston is moved to the open position. When the piston reaches the open position, the first pressure chamber communicates with the forward passage. As a result, the bypass path is opened. Then, a part of the refrigerant flowing in the forward path passes through the bypass path.

  Note that the refrigerant that reaches the return path from the forward path through the evaporator receives heat from the evaporator until the temperature of the evaporator sufficiently decreases. Therefore, during that time, the temperature of the refrigerant from the forward path to the return path through the bypass path is lower than the temperature of the refrigerant from the forward path to the return path through the evaporator. And the temperature of a temperature sensing part begins to fall with the comparatively low-temperature refrigerant | coolant which flows through a temperature detection flow path from a bypass path.

  Therefore, compared with the case where the refrigerant flows into the temperature detection flow path after flowing through the evaporator, the temperature of the temperature sensing unit is lowered earlier than when the refrigeration cycle apparatus is activated. As the temperature of the temperature sensing unit decreases, the throttle opening of the expansion valve decreases. Thereby, the refrigerant | coolant flow volume which flows through an evaporator also falls early. Thus, the increase in the refrigerant passing sound can be suppressed by reducing the throttle opening of the expansion valve earlier after the refrigeration cycle apparatus is activated.

  Thereafter, the refrigerant pressure in the first pressure chamber and the second pressure chamber connected through the throttle passage gradually becomes equalized. As a result, the urging force of the urging member gradually becomes more dominant than the force derived from the pressure difference between the first pressure chamber and the second pressure chamber, and the piston moves from the open position to the closed position. And move slowly. And when the position of the piston reaches the closed position, the bypass path is closed.

  Thus, by providing the throttle portion, a pressure difference is generated between the first pressure chamber and the second pressure chamber in a predetermined period when the refrigeration cycle apparatus is started. In such a configuration, the length of the predetermined period can be easily adjusted by adjusting the opening of the throttle portion. Therefore, the design of the bypass mechanism can be facilitated.

  In addition, the code | symbol in the bracket | parenthesis in the said and the claim shows the correspondence of the term described in the claim, and the concrete thing etc. which illustrate the said term described in embodiment mentioned later. .

It is a block diagram which shows the structure of a refrigeration cycle apparatus. It is a cross-sectional schematic diagram when the piston of a bypass mechanism exists in a closed position. It is a cross-sectional schematic diagram when the piston of a bypass mechanism exists in a closed position. It is a graph which shows the change of various amounts when a refrigerating cycle device starts under high temperature environment.

  Hereinafter, an embodiment of the present invention will be described. As shown in FIG. 1, the refrigeration cycle apparatus 1 of the embodiment includes a compressor 2, a condenser 3, a temperature type expansion valve 4, an evaporator 5, and a bypass mechanism 6. A receiver (not shown) may be arranged between the capacitor and the temperature type expansion valve 4.

  The compressor 2 sucks and compresses the gas-phase refrigerant from the upstream side of the refrigerant flow and discharges it to the downstream side of the refrigerant flow. Hereinafter, the refrigerant flow upstream side is simply referred to as the upstream side, and the refrigerant flow downstream side is simply referred to as the downstream side.

  The condenser 3 exchanges heat between the gas-phase refrigerant discharged from the compressor 2 and an external fluid (for example, air), thereby removing heat from the gas-phase refrigerant and condensing the gas-phase refrigerant.

  The temperature type expansion valve 4 is an external pressure equalization type expansion valve that is disposed downstream of the condenser 3 and upstream of the evaporator 5 and has a variable throttle opening. The temperature type expansion valve 4 is a throttle portion that narrows a part of the refrigerant flow path on the downstream side of the refrigerant flow of the condenser 3 and the upstream side of the refrigerant flow of the evaporator 5 during steady operation of the refrigeration cycle apparatus 1. Due to this action of the temperature type expansion valve 4, the refrigerant pressure is lower on the downstream side of the condenser 3 and on the upstream side of the evaporator 5 than on the upstream side of the temperature type expansion valve 4. That is, the temperature type expansion valve 4 decompresses and expands the refrigerant flowing out of the capacitor 3. The temperature type expansion valve 4 includes a main body portion 41, a valve body 42, a diaphragm operating portion 43, a temperature sensitive rod 44, an operating rod 45, and a spring 46.

  The main body 41 is a member that forms a decompression flow path 411 and a temperature detection flow path 412 through which the refrigerant passes, and has a valve seat 413. The decompression channel 411 guides the refrigerant flowing out of the capacitor 3 and passing through the refrigerant channel 7 to the refrigerant channel 15. The refrigerant flow path 15 is connected to the decompression flow path 411 at the upstream end and is connected to the bypass mechanism 6 at the downstream end. The temperature detection channel 412 guides the refrigerant flowing out of the bypass mechanism 6 and passing through the refrigerant channel 16 to the refrigerant channel 8. The refrigerant flow path 8 is connected to the temperature detection flow path 412 at the upstream end, and is connected to the compressor 2 at the downstream end. The valve seat 413 is an inner wall that faces the decompression channel 411 and faces the valve body 42.

  The valve body 42 is a movable member that is disposed in the decompression channel 411 and opens and closes the decompression channel 411. The valve body 42 adjusts the throttle opening degree of the decompression flow path 411 according to the relative distance from the valve seat 413. The throttle opening is the minimum value of the channel cross-sectional area between the valve body 42 and the valve seat 413 in the decompression channel 411.

  The smaller the throttle opening is, the smaller the minimum value of the channel cross-sectional area of the decompression channel 411 is, and the refrigerant flow passing through the decompression channel 411 is strongly throttled. The smaller the throttle opening is, the higher the value obtained by subtracting the pressure of the refrigerant on the downstream side from the pressure on the upstream side of the pressure reducing channel 411 (that is, the pressure difference).

  The diaphragm operation part 43 is fixed to the upper end part of the main body part 41 by screws or the like. The diaphragm operation unit 43 includes a casing 431 and a diaphragm 432. The casing 431 is an outer shell of the diaphragm operating portion 43 and is fixed to the upper end portion of the main body portion 41.

  The diaphragm 432 is a flexible film-like member, for example, a thin metal plate. The diaphragm 432 is disposed in an internal space surrounded by the casing 431. The entire circumference of the outer edge of the diaphragm 432 is closely fixed to the inner wall of the casing 431 facing the internal space. A working gas is sealed in the diaphragm chamber 433 surrounded by the diaphragm 432 and the upper part of the inner wall of the casing 431.

  A space surrounded by the diaphragm 432 and the lower part of the inner wall of the casing 431 is a part of the temperature detection flow path 412, and the refrigerant flows. Therefore, the diaphragm 432 is a partition member that separates the temperature detection flow path 412 and the diaphragm chamber 433.

  If there is a temperature difference between the working gas in the diaphragm chamber 433 and the diaphragm 432, heat is transferred immediately. The diaphragm 432 is displaced according to the pressure change of the working gas in the diaphragm chamber 433. For example, when the temperature of the working gas rises, the working gas expands the diaphragm chamber 433 and acts to displace the diaphragm 432 downward (that is, in the direction from the diaphragm 432 to the valve body 42).

  The temperature sensing rod 44 is made of aluminum having a high thermal conductivity, for example, and is a temperature sensing cylinder having a cylindrical shape. The temperature sensing rod 44 is arranged in the temperature detection flow path 412 so that the axial direction of the temperature sensing rod 44 intersects the refrigerant flow direction in the temperature detection flow path 412. That is, the temperature sensing rod 44 is disposed so as to cross a part of the temperature detection flow path 412 in the vertical direction. The upper end of the temperature sensing rod 44 is in contact with the diaphragm 432. With such an arrangement, the temperature sensing rod 44 mediates heat transfer between the refrigerant in the temperature detection flow path 412 and the diaphragm 432.

  The operating rod 45 is a member that operates the valve body 42. The operating bar 45 is disposed in series with the temperature sensing bar 44 in the vertical direction and below the temperature sensing bar 44. The operating rod 45 is in contact with the lower end of the temperature sensing rod 44 at the upper end, and is connected to the diaphragm 432 via the temperature sensing rod 44. Further, the valve body 42 is connected to the lower end of the operating rod 45 so as to be displaced in the vertical direction integrally with the operating rod 45. Therefore, the actuating rod 45 operates the valve body 42 to the side of decreasing the throttle opening of the temperature type expansion valve 4 as the diaphragm 432 is displaced to the side where the diaphragm chamber 433 is contracted (that is, the upper side).

  The spring 46 is an elastic member that urges the valve body 42 in the direction in which the valve body 42 approaches the valve seat 413 (that is, the direction in which the throttle opening is reduced).

  As described above, the valve body 42, the diaphragm operating portion 43, the temperature sensing rod 44, the actuation rod 45 and the spring 46 as a whole adjust the throttle opening of the temperature type expansion valve 4. Accordingly, the temperature change of the refrigerant in the temperature detection flow path 412 causes a change in the throttle opening of the temperature type expansion valve 4 due to a mechanical operation.

  Specifically, when the heating degree of the refrigerant in the temperature detection channel 412 increases, the temperature rises while the pressure of the refrigerant passing through the temperature detection channel 412 remains substantially constant. Then, the temperature of the working gas in the diaphragm chamber 433 rises to a temperature equivalent to the temperature of the refrigerant, and the saturation pressure in the diaphragm chamber 433 also rises. Therefore, when the heating degree of the refrigerant in the temperature detection channel 412 increases, a pressure difference obtained by subtracting the pressure in the temperature detection channel 412 from the pressure in the diaphragm chamber 433 increases. As a result, the throttle opening degree of the temperature type expansion valve 4 is increased, and the flow rate of the refrigerant flowing into the evaporator 5 is increased.

  When the degree of heating of the refrigerant in the temperature detection channel 412 decreases, the temperature decreases while the pressure of the refrigerant passing through the temperature detection channel 412 remains substantially constant. Then, the temperature of the working gas in the diaphragm chamber 433 decreases to a temperature equivalent to the temperature of the refrigerant, and the saturation pressure in the diaphragm chamber 433 also decreases. Therefore, when the degree of heating of the refrigerant in the temperature detection channel 412 decreases, the pressure difference obtained by subtracting the pressure in the temperature detection channel 412 from the pressure in the diaphragm chamber 433 decreases. As a result, the throttle opening of the temperature type expansion valve 4 is reduced and the flow rate of the refrigerant flowing into the evaporator 5 is reduced.

  Thus, the throttle opening degree of the temperature type expansion valve 4 is determined by the pressure difference obtained by subtracting the pressure in the temperature detection flow path 412 from the pressure in the diaphragm chamber 433. The pressure in the diaphragm chamber 433 is determined according to the temperature of the refrigerant flowing through the temperature detection flow path 412. Note that the temperature and pressure of the refrigerant flowing through the temperature detection channel 412 are the same as the temperature and pressure of the refrigerant at the outlet of the evaporator 5.

  The evaporator 5 is a heat exchanger that cools the conditioned air and evaporates the refrigerant by exchanging heat between the refrigerant and the conditioned air. The refrigerant flows out of the temperature type expansion valve 4 and flows through the refrigerant flow path 15 and the bypass mechanism 6 into the evaporator 5. Then, the refrigerant passing through the evaporator 5 flows into the temperature detection flow path 412 of the temperature type expansion valve 4 through the bypass mechanism 6 and the refrigerant flow path 16. The conditioned air cooled by the evaporator 5 is blown into the air conditioned space of the vehicle such as the passenger compartment, thereby cooling the air conditioned space.

  The diaphragm operating unit 43 and the temperature sensing rod 44 correspond to the temperature sensing unit of the temperature type expansion valve 4.

  During the steady operation of the refrigeration cycle apparatus 1, the bypass mechanism 6 causes the refrigerant that flows out of the temperature type expansion valve 4 and passes through the refrigerant flow path 15 to flow to the evaporator 5 through the refrigerant flow path 17, and from the evaporator 5. The refrigerant that has flowed out and passed through the refrigerant flow path 18 flows through the refrigerant flow path 16 to the temperature detection flow path 412 of the temperature type expansion valve 4.

  The specific configuration of the bypass mechanism 6 is as shown in FIGS. The bypass mechanism 6 includes a body 61, a compression coil spring 62, a piston 63, O-rings 64 a, 64 b, 64 c, a concave plug 65, and a throttle portion 66.

  The body 61 is an integral member in which an outward passage 71, a return passage 72, one bottomed hole 73, an outward passage side communication passage 74, and a return passage side communication passage 75 are formed. The forward passage 71 has an upstream end communicating with the refrigerant flow path 15 and a downstream end communicating with the refrigerant flow path 17. The return passage 72 has an upstream end communicating with the refrigerant flow path 18 and a downstream end communicating with the refrigerant flow path 16. The bottomed hole 73 is disposed between the forward passage 71 and the backward passage 72, one end side end in the moving direction of the piston 63 (right end in FIGS. 2 and 3) is closed, and the other end in the moving direction of the piston 63. The side is open to the outside of the body 61. In the bottomed hole 73, the compression coil spring 62, the piston 63, the piston 63, the O-rings 64a, 64b, 64c, and the concave plug 65 are accommodated.

  The body 61 includes an outward passage side outer shell portion 611, a return passage side outer shell portion 612, an outward passage side partition wall portion 613, a return passage side partition wall portion 614, a bottom portion 615, and the like. The forward passage side outer shell portion 611 is a wall that separates the forward passage 71 from the outside of the bypass mechanism 6. The return passage side outer shell portion 612 is a wall that separates the return passage 72 from the outside of the bypass mechanism 6. The forward passage side partition wall 613 is a wall that separates the forward passage 71 and the bottomed hole 73. The return passage side partition 614 is a wall that separates the return passage 72 and the bottomed hole 73. The bottom portion 615 is a wall that closes the bottom of the bottomed hole 73.

  The forward passage side communication passage 74 is a communication passage formed in the forward passage side partition 613, and communicates with the forward passage 71 at one end portion and communicates with the bottomed hole 73 at the other end portion. The return passage side communication passage 75 is a communication passage formed in the return passage side partition 614 and communicates with the return passage 72 at one end portion and communicates with the bottomed hole 73 at the other end portion. Thus, the forward passage 71 and the bottomed hole 73 communicate with each other via the forward passage side communication passage 74, and the return passage 72 and the bottomed hole 73 communicate with each other via the return passage side communication passage 75.

  The positions of the forward passage side communication passage 74 and the return passage side communication passage 75 are shifted in the movement direction of the piston 63. Specifically, the position of the forward passage side communication path 74 in the movement direction of the piston 63 is shifted to the concave plug 65 side than the position of the return path side communication path 75 in the movement direction of the piston 63.

  The compression coil spring 62 is accommodated in the bottomed hole 73, one end is in contact with the bottom 615, and the other end is fixed to the compression coil spring 62 side end of the piston 63. Since the compression coil spring 62 is not made of a shape memory alloy, the spring constant of the compression coil spring 62 hardly depends on the temperature of the compression coil spring 62. Actually, in the range from −50 ° C. to 150 ° C., the minimum value of the spring constant of the compression coil spring 62 is 90% or more of the maximum value. The compression coil spring 62 is always compressed more than the natural length by the piston 63 and the bottom 615 regardless of the position of the piston 63.

  The piston 63 is accommodated in the bottomed hole 73 and is disposed between the compression coil spring 62 and the concave plug 65. The piston 63 can move in the bottomed hole 73 in the left-right direction in FIGS. The piston 63 is a substantially bottomless cylindrical member, and the outer peripheral side is close to the inner wall (ie, the forward passage side partition 613, the return passage side partition 614, etc.) surrounding the bottomed hole 73 in the body 61. Oppositely, a communication hole 633 is formed on the inner side. The communication hole 633 is a part of the bottomed hole 73, one end communicates with the side of the bottomed hole 73 on which the compression coil spring 62 is disposed, and the other end is disposed with the concave plug 65 of the bottomed hole 73. Communicate to the designated side. Therefore, the side of the bottomed hole 73 where the compression coil spring 62 is disposed and the side where the concave plug 65 is disposed communicate with each other via the communication hole 633.

  Further, the end portion of the piston 63 on the compression coil spring 62 side has a step shape in order to increase the diameter of the communication hole 633. This step-shaped portion is a spring seat to which the compression coil spring 62 is fixed.

  Further, in the piston 63, an outward passage side connection hole 63 a that connects the outer peripheral space of the piston 63 and the communication hole 633 is formed in a side wall 63 y interposed between the communication hole 633 and the forward passage side partition wall 613. Yes. Further, in the piston 63, a return-side slit 63 b that connects the outer peripheral space of the piston 63 and the communication hole 633 is formed in the side wall 63 z interposed between the communication hole 633 and the return-passage partition wall 614. . The return passage side slit 63b is formed at the end of the side wall 63z on the compression coil spring 62 side.

  The positions of the forward passage side connection hole 63a and the return passage side slit 63b are shifted in the movement direction of the piston 63. Specifically, the position of the forward passage side connection hole 63a in the movement direction of the piston 63 is shifted to the concave plug 65 side than the position of the return passage side slit 63b in the movement direction of the piston 63. The positional deviation amounts of the forward passage side connection hole 63a and the return passage side slit 63b in the movement direction of the piston 63 are substantially the same as the positional deviation amounts of the forward passage side communication path 74 and the return passage side communication path 75 in the movement direction of the piston 63. It is.

  The throttle portion 66 is a member that protrudes from the wall surface of the piston 63 on the communication hole 633 side. The piston 63 and the throttle portion 66 are integrally formed. Therefore, the piston 63 is fixed to the throttle portion 66. The position of the throttle portion 66 in the movement direction of the piston 63 is shifted to the concave plug 65 side than the positions of the forward passage side connection hole 63a and the return passage side slit 63b in the movement direction of the piston 63. In the throttle passage 633a surrounded by the throttle portion 66, the flow passage cross-sectional area of the communication hole 633 is minimized. Accordingly, the throttle passage 633a allows the first pressure chamber P1 and the second pressure chamber P2 to communicate with each other and provides resistance to refrigerant flow between the first pressure chamber P1 and the second pressure chamber P2.

  The opening area of the throttle 66 (that is, the channel cross-sectional area of the throttle passage 633a) is sufficiently smaller than the minimum channel cross-sectional area of the forward passage side communication path 74, and the minimum channel cross-sectional area of the return path side communication path 75. Is sufficiently smaller than the minimum flow path cross-sectional area of the forward passage side connection hole 63a.

  The piston 63 is formed so as to be prohibited from rotating in the circumferential direction with respect to the body 61. For example, if the outer periphery of the piston 63 and the inner periphery of the body 61 have a non-cylindrical shape (for example, an elliptical cylindrical shape), such a configuration is realized.

  In this way, the gap on the opposite side of the concave plug 65 with respect to the throttle portion 66 inside the bottomed hole 73 becomes the first pressure chamber P1. The first pressure chamber P1 has a compression coil spring 62 side than the throttle portion 66 in the communication hole 633, a forward passage side connection hole 63a, a return passage side slit 63b, and a compression coil spring in the bottomed hole 73 than the throttle portion 66. It is formed by a void on the 62 side.

  The O-rings 64a, 64b, and 64c are seal members fixed to the outer periphery of the piston 63. O-rings 64 a, 64 b, and 64 c are interposed between the inner wall of the body 61 that surrounds the bottomed hole 73 and the outer periphery of the piston 63, so that the inner wall of the body 61 that surrounds the bottomed hole 73 and the outer periphery of the piston 63. Seal the space liquid tightly. Therefore, when the piston 63 moves in the bottomed hole 73 in the left-right direction in FIGS. 2 and 3, the O-rings 64 a, 64 b and 64 c slide with respect to the inner wall surrounding the bottomed hole 73 in the body 61. , Move together with the piston 63 together with the piston 63.

  The concave plug 65 is accommodated in the bottomed hole 73 and is fixed to the opposite side of the compression coil spring 62 with respect to the piston 63. The concave plug 65 closes the end portion on the open side of the bottomed hole 73 and has a hollow shape opened to the piston 63 side in the bottomed hole 73.

  The body 61 and the concave plug 65 constitute one frame, and this frame surrounds the internal space of the bypass mechanism 6. This internal space is a portion of the bottomed hole 73 other than the portion where the concave plug 65 is disposed. In the bottomed hole 73, the inner wall of the body 61, the recessed surface 651 of the recessed plug 65, the side surface of the recessed plug 65 of the piston 63, and the side surface of the recessed plug 65 of the throttle portion 66 surround the second pressure chamber P2.

  The internal space is partitioned into a first pressure chamber P1 and a second pressure chamber P2 by a piston 63. The piston 63 receives the pressure in the first pressure chamber P1 and is biased toward the second pressure chamber P2, and receives the pressure in the second pressure chamber P2 and is biased toward the first pressure chamber P1. . The piston 63 is always urged toward the second pressure chamber P2 by the compression coil spring 62. The compression coil spring 62 corresponds to an urging member.

  The first pressure chamber P1 and the second pressure chamber P2 communicate with each other through an opening formed by the throttle portion 66. Since the piston 63 can reciprocate, the volumes of the first pressure chamber P1 and the second pressure chamber P2 change according to the position of the piston 63.

  As shown in FIG. 3, the piston 63 can be moved in the right direction until the end of the piston 63 comes into contact with the bottom 615. In the state of FIG. 3, the volume of the first pressure chamber P1 is minimum.

  At this time, since the positions of the return passage side slit 63b and the return passage side communication passage 75 in the moving direction of the piston 63 overlap, the first pressure chamber P1 communicates with the return passage 72 via the return passage side communication passage 75. At this time, since the positions of the forward passage side connection hole 63a and the forward passage side communication passage 74 in the moving direction of the piston 63 overlap, the first pressure chamber P1 communicates with the forward passage 71 via the forward passage side communication passage 74. .

  The position where the return passage side slit 63b and the return passage side communication passage 75 communicate with each other and the forward passage side connection hole 63a and the forward passage side communication passage 74 communicate with each other is the opening position of the piston 63. When the piston 63 is in the open position, the forward passage 71, the forward passage side connection hole 63a, the communication hole 633, the return passage side slit 63b, the return passage side communication passage 75, and the return passage 72 are communicated in this order. A bypass path BP is formed from 71 to bypass the evaporator 5 and reach the return path 72.

  On the other hand, the diameter of the recessed surface 651 of the concave plug 65 is smaller than the outer diameter of the piston 63. For this reason, the piston 63 is restricted from moving in the left direction in FIGS. 2 and 3 by contact with the concave plug 65. The position of the piston 63 when the piston 63 and the concave plug 65 abut corresponds to the closed position. In the closed position, the side wall 63y of the piston 63 separates the forward passage 71 and the forward passage side communication passage 74 from the first pressure chamber P1. As a result, the forward passage side communication passage 74 and the first pressure chamber P1 do not communicate with each other, and the bypass route BP is closed. When the piston 63 is in this closed position, the volume of the second pressure chamber P2 becomes the amount corresponding to the recess of the concave plug 65.

  In addition, the return passage 72 and the first pressure chamber P1 communicate with each other regardless of the position of the piston 63 from the open position to the closed position. Therefore, the return passage 72 and the second pressure chamber P2 are always in communication.

  Further, as shown in FIG. 2, when the piston 63 is in the closed position, the forward passage side connection hole 63 a and the forward passage side communication passage 74 are arranged away from each other in the movement direction of the piston 63. In this case, in the moving direction of the piston 63, the O-ring 64b is closer to the concave plug 65 than the forward passage side communication passage 74, and the O-ring 64c is closer to the compression coil spring 62 than the forward passage side communication passage 74. . Accordingly, the bypass route BP is more reliably blocked.

  Further, as shown in FIG. 3, when the piston 63 is in the open position and the bypass path BP is formed, the O-ring 64a is closer to the concave plug 65 than the forward path side communication path 74 in the moving direction of the piston 63. It is in. Therefore, refrigerant leakage from the boundary between the forward passage side communication passage 74 and the forward passage side connection hole 63a to the second pressure chamber P2 is suppressed.

  Thus, the position of the piston 63 in the bypass mechanism 6 is determined by the balance between the force exerted on the piston 63 by the compression coil spring 62 and the force due to the pressure difference between the first pressure chamber P1 and the second pressure chamber P2.

  Here, a manufacturing method of the bypass mechanism 6 will be described. First, in the first step, the body 61, the compression coil spring 62, the piston 63, the O-rings 64a, 64b, 64c, and the concave plug 65 are manufactured and prepared. Subsequently, in the second step, O-rings 64 a, 64 b, 64 c are fixed to the outer periphery of the piston 63. Subsequently, in the third step, the compression coil spring 62 is fixed to the spring seat of the piston 63. Subsequently, in the fourth step, the compression coil spring 62, the piston 63, and the O-rings 64a, 64b, and 64c are inserted into the bottomed hole 73 from the opening of the bottomed hole 73. As a result, the compression coil spring 62 contacts the bottom 615. Subsequently, in the fifth step, the concave plug 65 is inserted into the bottomed hole 73 from the opening of the bottomed hole 73, and the concave plug 65 is fixed to the body 61. Thereby, the bypass mechanism 6 is completed. Since the concave plug 65 is a separate member from the body 61, the operation of arranging the compression coil spring 62, the piston 63, and the O-rings 64a, 64b, 64c in the bottomed hole 73 is facilitated as described above.

  Next, the operation of the refrigeration cycle apparatus 1 will be described. During steady operation of the refrigeration cycle apparatus 1, the compressor 2 operates to suck in refrigerant from the refrigerant flow path 8, and compress and discharge the sucked refrigerant. The discharged high-temperature refrigerant is heat-exchanged with the outside air by the condenser 3 to be condensed and condensed. The condensed refrigerant flows out of the condenser 3, passes through the refrigerant flow path 7, and flows into the decompression flow path 411 of the temperature type expansion valve 4. The refrigerant expands under reduced pressure in accordance with the throttle opening of the temperature type expansion valve 4 in the reduced pressure channel 411 and flows out to the refrigerant channel 15. As already described, the throttle opening degree of the temperature type expansion valve 4 increases as the heating degree of the refrigerant passing through the temperature detection flow path 412 increases, and decreases as the heating degree of the refrigerant passing through the temperature detection flow path 412 decreases. By such feedback control (more specifically, superheat control), the degree of heating of the refrigerant that has passed through the evaporator 5 is kept substantially constant.

  The refrigerant flows from the refrigerant flow path 15 into the forward passage 71 of the bypass mechanism 6. During the steady operation of the refrigeration cycle apparatus 1, since the piston 63 is in the closed position, the bypass path BP is closed. Therefore, all the fluid that has flowed into the forward passage 71 flows into the refrigerant flow path 17. The refrigerant flows from the refrigerant flow path 17 into the evaporator 5 and evaporates by exchanging heat with the conditioned air to cool the conditioned air. The cooled conditioned air is blown out into the air-conditioning target space of the vehicle such as the passenger compartment, thereby cooling the air-conditioning target space. The evaporated refrigerant flows from the evaporator 5 into the refrigerant flow path 18 and flows from the refrigerant flow path 18 into the return path 72 of the bypass mechanism 6. During steady operation of the refrigeration cycle apparatus 1, since the bypass path BP is closed, all the fluid that has flowed into the return path 72 flows into the refrigerant flow path 16. The refrigerant that has passed through the refrigerant flow path 16 passes through the temperature detection flow path 412 of the temperature type expansion valve 4, flows into the refrigerant flow path 8, and is further sucked into the compressor 2. As the refrigerant circulates in this manner, the air-conditioning target space of the vehicle continues to be cooled.

  Here, the reason why the bypass path BP is closed during the steady operation of the refrigeration cycle apparatus 1 will be described. Even when the piston 63 is in the closed position during the steady operation of the refrigeration cycle apparatus 1, the return passage 72 communicates with the second pressure chamber P2 via the first pressure chamber P1.

  For this reason, during the steady operation of the refrigeration cycle apparatus 1, the pressure in the first pressure chamber P1 is equal to the pressure in the second pressure chamber P2. That is, the first pressure chamber P1 and the second pressure chamber P2 are equalized. Since the piston 63 is always urged toward the concave plug 65 by the compression coil spring 62 in the compressed state, when the first pressure chamber P1 and the second pressure chamber P2 are equalized, the piston 63 is as shown in FIG. In a closed position. This state does not change even after the refrigeration cycle apparatus 1 stops the steady operation.

  Here, it is assumed that after the refrigeration cycle apparatus 1 stops the steady operation, the vehicle is left in the sun for a long time until time T1 shown in FIG. 4, and the refrigeration cycle apparatus 1 is started at time T1.

  Immediately before the time point T1, as shown in FIG. 4, the throttle opening 111 of the temperature type expansion valve 4 becomes zero. That is, the temperature type expansion valve 4 is fully closed. This is because, under a high temperature environment, the refrigerant pressure in the diaphragm chamber 433 and the refrigerant pressure in the decompression flow path 411 are substantially equal, and the valve body 42 is urged toward the valve seat 413 by the spring 46. . Further, the refrigerant flow rate 112 is zero immediately before the time point T1.

  Further, immediately before time T1, the position 113 of the piston 63 is in the closed position as described above. Therefore, as shown in FIG. 2, the bypass path BP is closed. That is, the forward passage 71 and the first pressure chamber P1 do not communicate via the forward passage side communication passage 74. However, the return passage 72 and the first pressure chamber P <b> 1 communicate with each other via the return passage side communication passage 75.

  Further, since the refrigerant is in a high temperature state immediately before time T1, the refrigerant pressure 115 just before the entrance of the evaporator 5 and the refrigerant pressure 116 just after the exit are very high. Further, immediately before time T1, the refrigerant pressure 117 in the first pressure chamber P1 and the refrigerant pressure 118 in the second pressure chamber P2 are also at the same high pressure.

  In addition, the continuous line 111-119 in FIG. 4 shows the time-dependent change of each quantity in the refrigerating-cycle apparatus 1 of this embodiment. The broken lines 101 to 109 indicate the respective amounts of time in the comparative example in which the bypass mechanism 6 is excluded from the refrigeration cycle apparatus 1, the refrigerant flow paths 15 and 17 are directly connected to each other, and the refrigerant flow paths 16 and 18 are directly connected to each other. Showing change.

  At time T1, the refrigeration cycle apparatus 1 starts operating when the compressor 2 starts to operate. Then, at time T1, the compressor 2 starts to suck in the refrigerant. As a result, the refrigerant pressures 115 and 116 in the evaporator 5 and the flow paths 15, 71, 17, 18, 72, and 16 before and after the evaporator 5 and the refrigerant pressure in the temperature detection flow path 412 rapidly decrease. However, because of the high temperature environment, the temperature 119 of the diaphragm chamber 433 does not decrease immediately. Therefore, the pressure difference obtained by subtracting the refrigerant pressure in the temperature detection flow path 412 from the pressure of the working gas in the diaphragm chamber 433 increases rapidly, and as a result, the throttle opening 111 of the expansion valve increases rapidly and opens greatly. It will be in the state (specifically fully open state).

  Then, the gas-liquid mixed refrigerant having a low temperature and a large refrigerant flow rate 112 decompressed by the depressurizing flow path 411 of the temperature type expansion valve 4 is deprived of heat by the condenser 3, and the evaporator 5, the refrigerant flow path 18, the return path 72, the refrigerant flow It flows through the channel 16 and the temperature detection channel 412. Even when the throttle opening of the temperature type expansion valve 4 is fully open, the refrigerant is decompressed in the decompression flow path 411.

  In this way, the expansion valve is fully opened immediately after the refrigeration cycle apparatus 1 is activated, and an excessive amount of refrigerant passes through the evaporator 5 and the refrigerant flow paths 16 and 18, whereby the evaporator 5 and the refrigerant flow paths 16 and 18. As a result, the volume 114 of the refrigerant passing sound increases.

  Further, at the same time when the refrigerant pressure in the return passage 72 and the temperature detection flow path 412 decreases, the refrigerant pressure 117 also decreases in the first pressure chamber P1 communicating with the return passage 72 via the return passage side communication passage 75. Begin to. However, since the throttle passage 633a exists between the first pressure chamber P1 and the second pressure chamber P2, as shown in FIG. 4, the decrease in the refrigerant pressure 118 in the second pressure chamber P2 is caused by the first pressure chamber P1. The refrigerant pressure 117 is delayed. That is, the refrigerant pressure in the second pressure chamber P2 is higher than the refrigerant pressure in the first pressure chamber P1.

  Therefore, the force derived from the pressure difference between the first pressure chamber P1 and the second pressure chamber P2 exceeds the urging force of the compression coil spring 62, and the position 113 of the piston 63 is moved to the open position. When the piston 63 reaches the open position, the forward passage side connection hole 63a and the forward passage side communication passage 74 communicate with each other as shown in FIG.

  Accordingly, the forward passage 71, the forward passage side connection hole 63a, the communication hole 633, the return passage side slit 63b, the return passage side communication passage 75, and the return passage 72 are communicated in this order. Thereby, the bypass path BP that bypasses the evaporator 5 from the forward path 71 and flows to the return path 72 through the first pressure chamber P1 is opened.

  Then, a part of the low-temperature refrigerant flowing in the forward path 71 passes through the bypass path BP, thereby bypassing the refrigerant flow path 17, the evaporator 5, and the refrigerant flow path 18, and returning to the return path 72, the refrigerant flow path 16, and the temperature. It flows to the detection flow path 412.

  In addition, since the refrigerant | coolant which reaches the return path 72 through the evaporator 5 from the going path 71 receives heat from the evaporator 5 until the temperature of the evaporator 5 fully falls, the temperature fall is slow. On the other hand, the refrigerant that reaches the return path 72 from the forward path 71 through the bypass path BP does not pass through the evaporator 5, and therefore the temperature is quickly lowered. Therefore, during that time, the temperature of the refrigerant from the forward path 71 through the bypass path BP to the return path 72 is lower than the temperature of the refrigerant from the forward path 71 through the evaporator 5 to the return path 72.

  The working gas in the diaphragm chamber 433 is cooled by the low-temperature refrigerant flowing through the temperature detection channel 412 via the temperature sensing rod 44 and the diaphragm 432. Then, the temperature of the working gas in the diaphragm chamber 433 starts to decrease.

  Therefore, compared with the case where the refrigerant flows through the refrigerant flow path 17, the evaporator 5, and the refrigerant flow path 18 and then flows into the temperature detection flow path 412, the refrigerant in the diaphragm chamber 433 is earlier than when the refrigeration cycle apparatus 1 is activated. The working gas temperature drops. As the temperature of the working gas decreases, the pressure of the working gas decreases, the valve body 42 approaches the valve seat 413, and the throttle opening degree of the temperature type expansion valve 4 decreases. Thereby, the refrigerant | coolant flow volume 112 which flows through the evaporator 5 also falls early. Thus, the increase in the volume 114 of the refrigerant passing sound is suppressed by lowering the throttle opening degree of the temperature type expansion valve 4 earlier after the refrigeration cycle apparatus 1 is activated.

  In the comparative example in which the bypass mechanism 6 is eliminated, the period from when the refrigeration cycle apparatus 1 is activated until the low-temperature refrigerant flows into the temperature detection flow path 412 corresponds to the absence of the bypass path BP from the present embodiment. Too long. For this reason, as shown in FIG. 4, the temperature 109 of the working gas in the diaphragm chamber 433 decreases, the throttle valve opening 101 of the expansion valve decreases, which is later than the present embodiment. As a result, in the comparative example, since the time when the refrigerant flow rate 102 passing through the evaporator 5 is excessive is longer than in this embodiment, the volume 104 of the refrigerant passing sound is larger than in this embodiment.

  Further, after the time T1, the refrigerant pressures 117 and 118 in the first pressure chamber P1 and the second pressure chamber P2 connected through the throttle passage 633a gradually become equalized. As a result, the urging force of the compression coil spring 62 gradually becomes more dominant than the force derived from the pressure difference between the first pressure chamber P1 and the second pressure chamber P2, and the piston 63 is closed from the open position. Move gradually toward the position. Then, at time T2 after a predetermined period from time T1, the position 113 of the piston 63 reaches the closed position. As a result, the bypass path BP is closed and the flow of the refrigerant passing therethrough is also cut off. In this embodiment, since the temperature 119 of the working gas and the throttle opening 111 of the temperature type expansion valve 4 are sufficiently lowered at the time T3 before the time T2, the superheat control is performed earlier than the comparative example. It becomes possible.

  The length of the period from time T1 to time T2 varies depending on various conditions such as the temperature of the refrigerant at time T1, the opening area of the throttle 66, and the volume of the second pressure chamber P2 when the piston 63 is in the closed position. It depends on. For example, the length of the period from time T1 to time T2 is about 10 seconds.

  Thus, according to the refrigeration cycle apparatus 1 of the present embodiment, a part of the refrigerant depressurized by the temperature expansion valve 4 is the time from when the bypass path BP is opened immediately after startup until it is closed. Then, the refrigerant flows into the refrigerant flow path 16 through the bypass path BP and flows into the temperature sensing part of the temperature type expansion valve 4 to be cooled. And since the temperature sensing part (specifically, the working gas of the diaphragm chamber 433) is quickly cooled, the superheat control of the temperature type expansion valve 4 can be performed at an early stage after the start, thereby suppressing the refrigerant flow rate and the refrigerant. Passing sound can be reduced.

  The bypass mechanism 6 for obtaining this function and effect has a relatively simple configuration including a body 61, a compression coil spring 62, a piston 63, O-rings 64a, 64b, 64c, and a concave plug 65. What needs to be considered in the design is the balance between the force derived from the pressure difference between the first pressure chamber P1 and the second pressure chamber P2 and the biasing force of the compression coil spring 62. Since the urging force of the compression coil spring 62 only needs to be in the closed position while the refrigerant pressure in the first pressure chamber P1 and the refrigerant pressure in the second pressure chamber P2 are the same, the selection of the compression coil spring 62 is easy. Therefore, the refrigeration cycle apparatus 1 in which the bypass mechanism 6 can be easily designed can be realized.

  In the present embodiment, the throttle passage 633a is formed in the piston 63. By doing so, the piston 63 moves and the throttle passage 633a also moves, so that the possibility that the throttle passage 633a is blocked by the movement of the piston 63 is reduced.

  Further, the forward passage side communication passage 74 and the return passage side communication passage 75 are shifted from each other in the moving direction of the piston 63. This shift is a shift that allows partial overlap. Thus, when the piston 63 is located at the closed position, the return passage side communication passage 75 communicates with the first pressure chamber P1, and the forward passage side communication passage 74 becomes the first pressure chamber P1. It becomes easy to be separated from. If the forward passage side communication passage 74 and the return passage side communication passage 75 are not shifted in the moving direction of the piston 63, one of the return passage side communication passage 75 and the forward passage side communication passage 74 is in the first pressure chamber P1. In the case of communication, there is a high possibility that the other will always communicate with the first pressure chamber P1.

  Thus, by providing the throttle portion 66, a pressure difference is generated between the first pressure chamber P1 and the second pressure chamber P2 during a predetermined period when the refrigeration cycle apparatus 1 is started. In such a configuration, the length of the predetermined period can be easily adjusted by adjusting the opening of the throttle portion 66. Therefore, the design of the bypass mechanism 6 can be facilitated.

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, in the above-described embodiment, elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where it is considered to be clearly essential in principle. Further, in the above embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is particularly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to a specific number except for cases. In particular, when a plurality of values are exemplified for a certain amount, it is also possible to adopt a value between the plurality of values unless specifically stated otherwise and in principle impossible. . In the above embodiment, when referring to the shape, positional relationship, etc. of components, the shape, position, etc., unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to relationships. The present invention also allows the following modifications to the above embodiment. In addition, the following modifications can select application and non-application to the said embodiment each independently. That is, any combination of the following modified examples excluding combinations that are clearly contradictory can be applied to the embodiment.

(Modification 1)
For example, the forward passage 71 of the bypass mechanism 6 can be interposed between the refrigerant flow path 7 and the decompression flow path 411. In this case, the bypass path BP is a flow path that bypasses not only the evaporator but also the decompression flow path 411. In this case, a throttle mechanism such as an orifice may be disposed between the refrigerant flow path 7 and the bypass mechanism 6, and the decompressed refrigerant may be supplied to the forward passage 71. In that case, the refrigerant passing through the bypass path BP has a lower temperature.

(Modification 2)
In the above embodiment, the compression coil spring 62 is used as the biasing member that biases the piston 63 toward the second pressure chamber P2. However, the urging member is not limited to the compression coil spring, and may be a spring of another form or an elastic body other than the spring. The urging member may be any member as long as it urges the piston 63 toward the second pressure chamber P2.

(Modification 3)
In the above-described embodiment, the throttle passage 633a may be formed in a portion other than the piston 63, for example, the body 61, instead of the piston 63.

(Modification 4)
In the above embodiment, the return passage side communication passage 75 and the first pressure chamber P <b> 1 communicate with each other from the open position to the closed position of the piston 63. However, this is not necessarily the case. For example, the return passage side communication passage 75 and the first pressure chamber P1 may communicate with each other only when the piston 63 is in the open position and in the closed position.

(Modification 5)
In the above embodiment, the external pressure equalizing type temperature type expansion valve 4 is illustrated, but this may be replaced with an internal pressure equalizing type expansion valve. In this case, the valve body 42 is displaced so that the throttle opening increases as the refrigerant pressure from the downstream side of the refrigerant flow of the valve body 42 to the evaporator 5 decreases.

  That is, the temperature type expansion valve 4 of this embodiment can move the valve body 42 so that the throttle opening increases as the refrigerant pressure on the downstream side of the refrigerant flow of the valve body 42 and the upstream side of the refrigerant flow of the compressor 2 decreases. That's fine.

(Modification 6)
In the above embodiment, the refrigeration cycle apparatus 1 is used to cool the air-conditioning target space in the vehicle, but the air-conditioning target space is not limited to the space in the vehicle, and may be indoors, in a freezer, or the like. .

(Modification 7)
In the above embodiment, the compression coil spring 62 is disposed on the first pressure chamber P1 side of the piston 63 and presses the piston 63 toward the second pressure chamber P2. However, the compression coil spring 62 may be disposed on the second pressure chamber P2 side of the piston 63. In this case, however, the compression coil spring 62 is disposed on the first pressure chamber P1 side and pulls the piston 63 toward the second pressure chamber P2.

(Summary)
According to the first aspect shown in a part or all of each of the above embodiments, the bypass mechanism is connected to the first and second pressure chambers, and the refrigerant flow resistance between the first and second pressure chambers is reduced. And a piston is movable between the first pressure chamber and the second pressure chamber. When the first and second pressure chambers are equalized, the piston is located in the closed position, the return passage communicates with the first pressure chamber via the return passage side communication passage, and the forward passage side communication passage is the first passage. Separated from one pressure chamber. When the refrigerant pressure in the second pressure chamber is higher than the refrigerant pressure in the first pressure chamber, the piston is located in the open position, and the forward passage and the first pressure chamber communicate with each other via the forward passage side communication passage. The return passage and the first pressure chamber communicate with each other through the passage-side communication passage to open the bypass route BP.

  Further, according to a second aspect, the forward passage is on the refrigerant flow downstream side of the expansion valve and on the refrigerant flow upstream side of the evaporator. In this way, the refrigerant that has been depressurized by the temperature-type expansion valve and further cooled down flows through the temperature detection flow path at an early stage through the bypass path, so that the temperature of the temperature-sensing portion can be lowered more quickly.

  According to a third aspect, the throttle passage is formed in the piston. Since the piston moves as well as the throttle passage, the possibility that the throttle passage is blocked by the movement of the piston is reduced.

  According to a fourth aspect, the forward passage side communication passage and the return passage side communication passage are displaced in the moving direction of the piston. In this way, when the piston is in the closed position, the return side communication path communicates with the first pressure chamber and the forward path side communication path is separated from the first pressure chamber. Easy to do. If the forward passage side communication passage and the return passage side communication passage are not displaced in the direction of movement of the piston, one of the return passage side communication passage and the forward passage side communication passage always communicates with the first pressure chamber. However, the possibility of communication with the first pressure chamber is increased.

4 Thermal expansion valve 6 Bypass mechanism 411 Depressurization flow path 412 Temperature detection flow path 43 Diaphragm operation part (temperature sensing part)
44 Temperature Sensing Bar (Temperature Sensing Section)
63 Piston 66 Restriction part P1 1st pressure chamber P2 2nd pressure chamber

Claims (4)

A compressor (2) for sucking and compressing and discharging a refrigerant;
A condenser (3) for condensing the refrigerant discharged from the compressor;
An expansion valve (4) for adjusting the throttle opening degree of the decompression flow path (411) through which the refrigerant flowing out of the condenser passes;
An evaporator (5) for evaporating the refrigerant flowing out of the expansion valve;
A bypass mechanism (6) for bypassing the evaporator and flowing the refrigerant,
The expansion valve includes a temperature sensing section (43, 44) whose temperature changes according to the temperature of the refrigerant in the temperature detection flow path (412) on the downstream side of the refrigerant flow of the evaporator and on the upstream side of the refrigerant flow of the compressor, A valve body (42) that moves according to the temperature of the temperature sensing part,
The valve body moves so that the throttle opening increases as the temperature of the temperature sensing unit increases, and the lower the refrigerant pressure on the refrigerant flow downstream side of the valve body and the refrigerant flow upstream side of the compressor, Move the valve body to increase the throttle opening,
The bypass mechanism is movable between the first pressure chamber (P1) and the second pressure chamber (P2) under the pressure of the first pressure chamber (P1) and the pressure of the second pressure chamber (P2). A piston (63), a biasing member (62) for biasing the piston toward the second pressure chamber, and the first pressure chamber and the first pressure chamber. And a throttle portion (66) that provides resistance to the flow of refrigerant between the second pressure chamber and the second pressure chamber,
When the refrigerant pressure in the first pressure chamber and the refrigerant pressure in the second pressure chamber are equalized, the piston is located in the closed position;
When the piston is located at the closed position, the return passage communicates with the first pressure chamber, and the forward passage is separated from the first pressure chamber by the piston,
When the refrigerant pressure in the second pressure chamber is higher than the refrigerant pressure in the first pressure chamber, the piston is located in the open position;
When the piston is located at the open position, the forward passage and the first pressure chamber communicate with each other, and the return passage and the first pressure chamber communicate with each other, thereby bypassing the evaporator from the forward passage. And a bypass path (BP) flowing through the first pressure chamber to the return path is opened.   2. The refrigeration cycle apparatus according to claim 1, wherein the forward passage is on the downstream side of the refrigerant flow of the expansion valve and on the upstream side of the refrigerant flow of the evaporator.   The refrigeration cycle apparatus according to claim 1 or 2, wherein the throttle portion is fixed to the piston.   The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the forward passage side communication passage and the return passage side communication passage are shifted in a moving direction of the piston.

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