JP2018155451A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device having a compact configuration and capable of suppressing a temperature rise of a refrigerant discharged from a compressor.SOLUTION: A refrigeration cycle device 10 includes: a compressor 12 for compressing and discharging a refrigerant; a condenser 14 for condensing the refrigerant discharged from the compressor 12; an expansion valve 18 for expanding the refrigerant flowing out from the condenser 14; and an evaporator 20 for evaporating the refrigerant flowing out from the expansion valve 18. The refrigeration cycle device 10 also includes: a bypass passage section 30 for causing the refrigerant flowing out from the expansion valve 18 to bypass the evaporator 20 and flow on a refrigerant suction side of the compressor 12; and a bypass valve 36 for opening/closing the bypass passage section 30. The refrigeration cycle device 10 further includes a solenoid valve control section 500 for controlling the bypass valve 36 so that the bypass passage section 30 is opened when a temperature of the refrigerant discharged from the compressor 12 exceeds a predetermined opening reference temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vapor compression refrigeration cycle apparatus.

  Conventionally, as the refrigeration cycle apparatus, a part of the liquid refrigerant after passing through the condenser is introduced to the refrigerant suction side of the compressor to suppress an excessive increase in the discharge temperature of the refrigerant discharged from the compressor. Is known (see, for example, Patent Document 1).

JP, 2014-102051, A

  However, as in Patent Document 1, in the refrigeration cycle apparatus, when a part of the liquid refrigerant is introduced from the refrigerant outlet side of the high pressure condenser to the refrigerant inlet side of the low pressure compressor, from the refrigerant outlet side of the condenser. A decompression mechanism is essential for the bypass circuit that guides the refrigerant to the refrigerant suction side of the compressor. In Patent Document 1, a capillary tube is used as a pressure reducing mechanism disposed in the bypass circuit. However, since the pressure difference between the refrigerant outlet side of the condenser and the refrigerant suction side of the compressor is large, the length of the capillary tube is small. It gets bigger. This is not preferable because it becomes a factor that hinders downsizing of the refrigeration cycle apparatus.

  An object of this invention is to provide the refrigerating-cycle apparatus which can suppress the temperature rise of the refrigerant | coolant discharged from the compressor with a compact structure in view of the said point.

In order to achieve the above object, the invention described in claim 1 is a vapor compression refrigeration cycle apparatus,
A compressor (12) for compressing and discharging the refrigerant;
A condenser (14) for condensing the refrigerant discharged from the compressor;
An expansion valve (18) for expanding the refrigerant flowing out of the condenser;
An evaporator (20) for evaporating the refrigerant flowing out of the expansion valve;
A bypass passage portion (30) for flowing the refrigerant flowing out of the expansion valve to the refrigerant suction side of the compressor, bypassing the evaporator;
An electromagnetic valve (36) for opening and closing the bypass passage;
An electromagnetic valve controller (500) for controlling the electromagnetic valve so that the bypass passage is opened when the temperature of the refrigerant discharged from the compressor exceeds a predetermined opening reference temperature;
Is provided.

  According to this, when the temperature of the refrigerant discharged from the compressor exceeds the open reference temperature, the low-temperature refrigerant flowing out from the expansion valve is introduced to the refrigerant suction side of the compressor via the bypass passage portion. The compressor is cooled. Thereby, the temperature rise of the refrigerant | coolant discharged from the compressor is suppressed.

  Furthermore, since the bypass passage is connected to the relatively close parts of the refrigerant outlet side of the expansion valve and the refrigerant suction side of the compressor, a pressure reducing mechanism for reducing the pressure of the refrigerant with respect to the bypass passage is unnecessary. It becomes.

  Therefore, according to this indication, the refrigerating cycle device which can control the temperature rise of the refrigerant discharged from the compressor can be realized with a compact configuration.

  The invention according to claim 2 has a high temperature side heat exchange section (221) through which the refrigerant flowing out from the condenser flows and a low temperature side heat exchange section (222) through which the refrigerant flowing out from the evaporator flows, An internal heat exchanger (22) that exchanges heat between the refrigerant flowing through the heat exchange section and the refrigerant flowing through the low temperature side heat exchange section is provided. The bypass passage is provided with a refrigerant inflow portion (320) into which refrigerant flows in between the refrigerant outlet side of the expansion valve and the refrigerant inlet side of the evaporator, and a refrigerant outflow portion (340) through which the refrigerant flows out. It is provided between the refrigerant outlet side of the low temperature side heat exchange section and the refrigerant suction side of the compressor.

  Thus, in the configuration including the internal heat exchanger for exchanging heat between the refrigerant flowing out of the condenser and the refrigerant flowing out of the evaporator, the enthalpy on the refrigerant outlet side of the condenser is reduced, and the refrigerant outlet side of the evaporator Since the enthalpy difference from the refrigerant inlet side increases, the refrigeration capacity can be improved.

  However, in the configuration including the internal heat exchanger, the temperature of the refrigerant flowing out from the low-temperature side heat exchanging unit rises, so the temperature of the refrigerant sucked into the compressor rises, and the cooling effect of the compressor decreases. There is a concern that

  On the other hand, in the refrigeration cycle apparatus of the present disclosure, the refrigerant outflow portion of the bypass passage portion is provided between the refrigerant outlet side of the low temperature side heat exchange portion and the refrigerant suction side of the compressor. According to this, since the low temperature refrigerant flowing out from the expansion valve is introduced to the refrigerant suction side of the compressor, the temperature rise of the refrigerant sucked into the compressor is suppressed, so that the compressor is sufficiently cooled. Can do.

  Therefore, according to this indication, the refrigerating cycle device which can control the fall of the refrigerating capacity at the time of suppressing the temperature rise of the refrigerant discharged from the compressor is realizable with a compact composition.

  In addition, the code | symbol in the parenthesis of each means described in this column and the claim shows an example of a correspondence relationship with the specific means described in the embodiment described later.

1 is a schematic configuration diagram of a refrigeration cycle apparatus according to a first embodiment. It is typical sectional drawing which shows the connection site | part of the 1st low pressure passage part and bypass passage part of the refrigerating cycle device concerning a 1st embodiment. It is a flowchart which shows the flow of the control processing which the control apparatus of the refrigerating-cycle apparatus which concerns on 1st Embodiment performs. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of closing of the bypass channel | path part of the refrigerating-cycle apparatus which concerns on 1st Embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of opening of the bypass channel | path part of the refrigerating-cycle apparatus which concerns on 1st Embodiment. It is typical sectional drawing which shows the connection site | part of the 1st low pressure passage part and bypass passage part of the refrigeration cycle apparatus used as the modification of 1st Embodiment. It is a schematic block diagram of the refrigerating-cycle apparatus which concerns on 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same or equivalent parts as those described in the preceding embodiments are denoted by the same reference numerals, and the description thereof may be omitted. Further, in the embodiment, when only a part of the constituent elements are described, the constituent elements described in the preceding embodiment can be applied to the other parts of the constituent elements. The following embodiments can be partially combined with each other even if they are not particularly specified as long as they do not cause any trouble in the combination.

(First embodiment)
The present embodiment will be described with reference to FIGS. In the present embodiment, an example in which the refrigeration cycle apparatus 10 of the present invention is applied to a freezer mounted on a trailer or the like will be described. The refrigeration cycle apparatus 10 of the present embodiment functions as a refrigerator that cools the blown air that is blown into a freezer that is a space to be cooled until it reaches an extremely low temperature of about −30 ° C. to −10 ° C. The refrigeration cycle apparatus 10 constitutes a vapor compression refrigeration cycle.

  As shown in FIG. 1, the refrigeration cycle apparatus 10 includes a compressor 12 that compresses and discharges a refrigerant. The compressor 12 is configured to be driven by a rotational driving force output from an engine (not shown). The compressor 12 may be configured to be driven by a rotational driving force from an electric motor.

  A condenser 14 is connected to the refrigerant discharge side of the compressor 12. The condenser 14 is a radiator that condenses the high-temperature and high-pressure gas refrigerant discharged from the compressor 12 by exchanging heat with outside air blown by an outdoor fan (not shown).

  A receiver 16 is connected to the refrigerant outlet side of the condenser 14. The receiver 16 separates the gas-liquid refrigerant flowing out of the condenser 14 and derives the liquid refrigerant. The receiver 16 of the present embodiment is configured by a gas-liquid separator with a liquid storage function that stores excess liquid refrigerant in the cycle.

  An expansion valve 18 is connected to the refrigerant outlet side of the receiver 16 via a high temperature side heat exchanging part 221 of the internal heat exchanger 22 described later. The expansion valve 18 is a decompression device that decompresses and expands the gas refrigerant flowing out from the receiver 16. The expansion valve 18 is composed of an electromagnetic valve whose valve opening can be adjusted in accordance with a control signal from a control device 50 described later. The expansion valve 18 is controlled by the control device 50 so that the degree of superheat on the refrigerant outlet side of the evaporator 20 becomes a predetermined value. The expansion valve 18 has, for example, a temperature sensing part arranged on the refrigerant outlet side of the evaporator 20, and the valve opening degree is adjusted so that the degree of superheat on the refrigerant outlet side of the evaporator 20 becomes a predetermined value. A mechanical expansion valve may be used.

  An evaporator 20 is connected to the refrigerant outlet side of the expansion valve 18. The evaporator 20 is a heat absorber that evaporates the refrigerant by exchanging heat between the low-temperature and low-pressure refrigerant decompressed and expanded by the expansion valve 18 and the interior air blown by an indoor fan (not shown). The internal air is cooled to a desired temperature by the endothermic action of the refrigerant in the evaporator 20.

  A refrigerant flow downstream of the evaporator 20 is connected to an internal heat exchanger 22. The internal heat exchanger 22 is a heat exchanger that exchanges heat between the high-temperature and high-pressure refrigerant flowing out from the receiver 16 and the low-temperature and low-pressure refrigerant flowing out from the evaporator 20. The internal heat exchanger 22 includes a high-temperature side heat exchange unit 221 through which high-temperature and high-pressure refrigerant flowing out from the receiver 16 flows, and a low-temperature side heat exchange unit 222 through which low-temperature and low-pressure refrigerant flowing out from the evaporator 20 flows.

  The internal heat exchanger 22 is configured by a double-pipe heat exchanger in which the high-temperature and high-pressure refrigerant flow path covers the outside of the low-temperature and low-pressure refrigerant flow path. Note that the internal heat exchanger 22 may be configured by a stacked heat exchanger in which high-temperature and high-pressure refrigerant flow paths and low-temperature and low-pressure refrigerant flow paths are alternately stacked.

  The refrigerant outlet side of the low temperature side heat exchanging part 222 of the internal heat exchanger 22 is connected to the refrigerant suction side of the compressor 12. The refrigerant that has flowed out of the low temperature side heat exchanging unit 222 is sucked into the compressor 12 and then compressed, and is discharged toward the refrigerant inlet side of the condenser 14.

  By the way, in the refrigerating cycle apparatus 10, the temperature of the refrigerant | coolant discharged from the compressor 12 may rise excessively, for example at the time of high load driving | operation. When the temperature of the refrigerant discharged from the compressor 12 rises excessively, problems such as deterioration of refrigerating machine oil contained in the refrigerant easily occur. For this reason, in the refrigeration cycle apparatus 10, the compressor 12 needs to be cooled and protected.

  On the other hand, the refrigeration cycle apparatus 10 according to the present embodiment includes a bypass passage portion 30 that causes the low-temperature and low-pressure refrigerant that has flowed out of the expansion valve 18 to flow around the evaporator 20 to the refrigerant suction side of the compressor 12. Yes.

  One end side of the bypass passage portion 30 is connected to a branch portion 32 provided in the first low-pressure passage portion 24, and the other end side is connected to a junction portion 34 provided in the second low-pressure passage portion 26. Note that the first low-pressure passage portion 24 is a main refrigerant passage portion that connects the refrigerant outlet side of the expansion valve 18 and the refrigerant inlet side of the evaporator 20 in the refrigeration cycle apparatus 10. The second low-pressure passage portion 26 is a downstream-side refrigerant passage portion that connects the refrigerant outlet side of the evaporator 20 and the refrigerant suction side of the compressor 12 in the refrigeration cycle apparatus 10.

  In the refrigeration cycle apparatus 10 of the present embodiment, a branch portion 32 is provided between the refrigerant outlet side of the expansion valve 18 and the refrigerant inlet side of the evaporator 20. Further, in the refrigeration cycle apparatus 10 of the present embodiment, a merging section 34 is provided between the refrigerant outlet side of the low temperature side heat exchanging section 222 of the internal heat exchanger 22 and the refrigerant suction side of the compressor 12.

  In the present embodiment, the part connected to the branch part 32 in the bypass passage part 30 constitutes the refrigerant inflow part 320 into which the refrigerant flows, and the part connected to the junction part 34 in the bypass passage part 30 flows out of the refrigerant. The refrigerant outflow part 340 is configured.

  By the way, when the bypass passage part 30 is always open, the low-temperature and low-pressure refrigerant that has flowed out of the expansion valve 18 flows into the bypass passage part 30, thereby reducing the mass flow rate of the refrigerant flowing into the evaporator 20. This is not preferable because it causes a decrease in the refrigeration capacity of the refrigeration cycle apparatus 10.

  Therefore, the refrigeration cycle apparatus 10 of the present embodiment is provided with a bypass valve 36 that opens and closes the bypass passage 30 with respect to the bypass passage 30. The bypass valve 36 is configured by an electromagnetic valve that is controlled to open and close in response to a control signal from a control device 50 described later.

  The bypass valve 36 is controlled to be in an open state at the time of abnormality such that the temperature of the refrigerant discharged from the compressor 12 increases excessively. For this reason, as the bypass valve 36, it is desirable to employ a normally-closed electromagnetic valve that is closed when not energized.

  In addition, the refrigeration cycle apparatus 10 of the present embodiment is based on the dryness of the refrigerant that has flowed out of the expansion valve 18 with respect to the bypass passage 30 in order to suppress a decrease in the refrigeration capacity when the refrigerant flows into the bypass passage 30. Also, a refrigerant having a large dryness flows in. That is, in the refrigeration cycle apparatus 10 of the present embodiment, the refrigerant inflow portion 320 has the first refrigerant inflow portion 320 such that the bypass passage 30 has a dryness greater than the dryness of the refrigerant flowing through the first low pressure passage portion 24. 1 It is connected to the low pressure passage 24.

  Here, from the viewpoint of suppressing a decrease in the refrigeration capacity of the refrigeration cycle apparatus 10, it is desirable that the liquid-rich refrigerant flows to the evaporator 20 side rather than the bypass passage portion 30 side. The liquid refrigerant has a higher density than the gas refrigerant. For this reason, the liquid refrigerant is less likely to flow in the direction against gravity, that is, the direction toward the upper side in the vertical direction DRud, as compared with the gas refrigerant.

  Focusing on this point, in the present embodiment, as shown in FIG. 2, the flow direction of the refrigerant flowing into the refrigerant inflow portion 320 of the bypass passage portion 30 is directed upward in the vertical direction DRud. The refrigerant inflow portion 320 is connected to the first low pressure passage portion 24. In other words, the bypass passage portion 30 has a flow direction F1 of the refrigerant flowing into the refrigerant inflow portion 320 that is higher in the vertical direction DRud than the flow direction F2 of the refrigerant flowing through the branch portion 32 of the first low-pressure passage portion 24. It is connected to the first low-pressure passage portion 24 so as to be close to the direction of heading.

  More specifically, the first low-pressure passage portion 24 of the present embodiment has a configuration in which a portion near the branch portion 32 extends along the horizontal direction DRh. And the bypass channel | path part 30 of this embodiment becomes a structure where the refrigerant | coolant inflow part 320 extends along the perpendicular direction DRud so that it may orthogonally cross with the 1st low voltage | pressure channel | path part 24. FIG.

  According to this, in the gas-liquid two-phase refrigerant flowing out from the expansion valve 18, the liquid-rich refrigerant flows toward the first low-pressure passage portion 24, and the gas-rich refrigerant easily flows into the bypass passage portion 30. That is, the refrigerant having a dryness greater than the dryness of the refrigerant flowing through the first low-pressure passage portion 24 easily flows into the bypass passage portion 30. In addition, the 1st low voltage | pressure channel | path part 24 may be the structure where the site | part of the branch part 32 vicinity extends along the direction slightly inclined with respect to the horizontal direction DRh. Further, the bypass passage portion 30 may be configured to extend along a direction in which the refrigerant inflow portion 320 is slightly inclined with respect to the vertical direction DRud.

  Here, the refrigerant flow downstream side of the branching portion 32 in the first low-pressure passage portion 24 includes the low temperature side heat exchange portion 222 of the evaporator 20 and the internal heat exchanger 22, and therefore, compared to the bypass passage portion 30 side, The flow resistance of the refrigerant increases. For this reason, when the bypass valve 36 is controlled to be in the open state, there is a concern that the refrigerant flows excessively with respect to the bypass passage portion 30.

  Therefore, in the present embodiment, the inner diameter D1 of the bypass passage 30 is smaller than the inner diameter D2 of the first low-pressure passage 24 in order to prevent the refrigerant from flowing excessively with respect to the bypass passage 30. .

  In addition, as a method of suppressing the refrigerant from flowing excessively with respect to the bypass passage portion 30, the length of the bypass passage portion 30 is made larger than the lengths of the first low-pressure passage portion 24 and the second low-pressure passage portion 26. Can be considered.

  However, increasing the length of the bypass passage 30 is a factor that increases the size of the refrigeration cycle apparatus 10. For this reason, as in this embodiment, the internal diameter D1 of the bypass passage portion 30 is made smaller than the inner diameter D2 of the first low-pressure passage portion 24, thereby suppressing the refrigerant from flowing excessively with respect to the bypass passage portion 30. It is desirable that

  Next, the control apparatus 50 which comprises the electric control part of the refrigerating-cycle apparatus 10 is demonstrated with reference to FIG. The control device 50 includes a known microcomputer including a processor, a storage unit, and the like and peripheral circuits thereof. The storage unit of the control device 50 is configured with a non-transitional tangible storage medium.

  Various sensors such as a discharge temperature sensor 52 that detects the temperature of the refrigerant discharged from the compressor 12 are connected to the input side of the control device 50. The control device 50 can acquire detection signals from various sensors such as the discharge temperature sensor 52. For convenience of explanation, hereinafter, the temperature of the refrigerant discharged from the compressor 12 may be referred to as a discharge refrigerant temperature Td.

  Further, the control device 50 is connected to various devices to be controlled such as the compressor 12, the expansion valve 18 and the bypass valve 36 on the output side. The operations of various devices to be controlled such as the compressor 12, the expansion valve 18, and the bypass valve 36 are controlled according to a control signal from the control device 50.

  The control device 50 configured as described above performs arithmetic processing on various signals input from various sensors in accordance with a program stored in the storage unit in advance, and is connected to the output side based on the result of the arithmetic processing. Control various controlled devices. The control device 50 according to the present embodiment controls the operation of the bypass valve 36 according to the detection value of the discharge temperature sensor 52.

  Here, the control device 50 includes a processing execution unit configured by hardware and software for executing various arithmetic processes, a control unit configured by hardware and software for controlling various devices to be controlled, and the like. ing. In the control device 50, for example, an electromagnetic valve control unit 500 that controls the opening / closing operation of the bypass valve 36 is integrated.

  Next, the control process which the control apparatus 50 of the refrigerating-cycle apparatus 10 of this embodiment performs is demonstrated with reference to the flowchart of FIG. When the operation switch of the refrigeration cycle apparatus 10 (not shown) is turned on, the control device 50 executes the control process shown in FIG. In addition, each control step of the control process shown in FIG. 3 constitutes a function realization unit that realizes various functions executed by the control device 50.

  As illustrated in FIG. 3, the control device 50 acquires various signals input from various sensors in step S <b> 10. Then, in step S20, the control device 50 determines whether or not the discharge refrigerant temperature Td detected by the discharge temperature sensor 52 has exceeded a predetermined open reference temperature Ttho. The open reference temperature Ttho is set to a value close to the allowable heat-resistant temperature of various components on the high-pressure side of the refrigeration cycle apparatus 10, refrigerant, refrigeration oil, and the like.

  When the discharged refrigerant temperature Td is equal to or lower than the open reference temperature Ttho, the control device 50 controls the bypass valve 36 to be closed so that the bypass passage 30 is closed in step S30.

  Thereby, the refrigeration cycle apparatus 10 becomes a refrigerant circuit in which the refrigerant flowing out from the expansion valve 18 does not flow into the bypass passage portion 30. When the compressor 12 is operated in this refrigerant circuit, the refrigerant is compressed and discharged by the compressor 12. The state of the refrigerant at this time is point A1 in FIG.

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 12 is condensed by exchanging heat with the outside air blown from the outdoor fan in the condenser 14. Further, the refrigerant flowing out of the condenser 14 is gas-liquid separated by the receiver 16. That is, the state of the refrigerant shifts from point A1 to point A2 in FIG.

  The liquid refrigerant that has flowed out of the receiver 16 is further cooled by the high temperature side heat exchanging part 221 of the internal heat exchanger 22 to be in a supercooled state. That is, the state of the refrigerant shifts from point A2 to point A3 in FIG.

  In addition, the liquid refrigerant that has flowed out of the high temperature side heat exchanging part 221 of the internal heat exchanger 22 is expanded under reduced pressure by the expansion valve 18, thereby becoming a gas-liquid two-phase state. That is, the state of the refrigerant shifts from point A3 to point A4 in FIG.

  The refrigerant that has flowed out of the expansion valve 18 flows into the evaporator 20 through the first low-pressure passage portion 24 because the bypass passage portion 30 is closed by the bypass valve 36. And the refrigerant | coolant which flowed into the evaporator 20 absorbs heat from the internal air blown from an indoor fan, evaporates, and will be in a gaseous-phase state. That is, the state of the refrigerant shifts from point A4 to point A5 in FIG.

  The temperature of the refrigerant that has flowed out of the evaporator 20 rises due to heat exchange with the refrigerant that flows through the high temperature side heat exchange unit 221 at the low temperature side heat exchange unit 222 of the internal heat exchanger 22. That is, the state of the refrigerant shifts from point A5 to point A6 in FIG.

  The refrigerant that has flowed out of the low temperature side heat exchanging section 222 of the internal heat exchanger 22 is sucked into the compressor 12 and compressed again. That is, the state of the refrigerant shifts from point A6 in FIG. 4 to point A1.

  As described above, when the discharged refrigerant temperature Td is equal to or lower than the open reference temperature Ttho, the refrigeration cycle apparatus 10 cools the internal air when the refrigerant exhibits an endothermic action in the evaporator 20.

  Returning to FIG. 3, when the discharged refrigerant temperature Td exceeds the open reference temperature Ttho in step S20, the control device 50 opens the bypass valve 36 so that the bypass passage 30 is opened in step S40. Control to the state.

  Thereby, the refrigeration cycle apparatus 10 becomes a refrigerant circuit in which a part of the refrigerant that has flowed out of the expansion valve 18 flows into the bypass passage portion 30. When the compressor 12 is operated in this refrigerant circuit, the refrigerant is compressed and discharged by the compressor 12. The state of the refrigerant at this time is point B1 in FIG.

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 12 is condensed by exchanging heat with the outside air blown from the outdoor fan in the condenser 14. Further, the refrigerant flowing out of the condenser 14 is gas-liquid separated by the receiver 16. That is, the state of the refrigerant shifts from point B1 to point B2 in FIG.

  The liquid refrigerant that has flowed out of the receiver 16 is further cooled by the high temperature side heat exchanging part 221 of the internal heat exchanger 22 to be in a supercooled state. That is, the state of the refrigerant shifts from point B2 to point B3 in FIG.

  In addition, the liquid refrigerant that has flowed out of the high temperature side heat exchanging part 221 of the internal heat exchanger 22 is expanded under reduced pressure by the expansion valve 18, thereby becoming a gas-liquid two-phase state. That is, the state of the refrigerant shifts from point B3 to point B4 in FIG.

  The refrigerant flowing out of the expansion valve 18 flows into the evaporator 20 through the first low pressure passage portion 24 and also into the bypass passage portion 30 because the bypass passage portion 30 is opened by the bypass valve 36.

  At this time, the refrigerant inflow portion 320 of the bypass passage portion 30 is connected to the branch portion 32 of the first low pressure passage portion 24 so that the refrigerant having a dryness larger than the dryness of the refrigerant flowing through the first low pressure passage portion 24 flows. Has been. For this reason, the liquid-rich refrigerant having a lower dryness than the refrigerant flowing into the bypass passage portion 30 flows into the evaporator 20. And the refrigerant | coolant which flowed into the evaporator 20 absorbs heat from the internal air blown from an indoor fan, evaporates, and will be in a gaseous-phase state. That is, the state of the refrigerant shifts from point B4 to point B5 in FIG.

  The temperature of the refrigerant that has flowed out of the evaporator 20 rises due to heat exchange with the refrigerant that flows through the high temperature side heat exchange unit 221 at the low temperature side heat exchange unit 222 of the internal heat exchanger 22. That is, the state of the refrigerant shifts from point B5 to point B6 in FIG.

  Then, the refrigerant that has flowed out of the low temperature side heat exchanging unit 222 of the internal heat exchanger 22 joins with the refrigerant that flows through the bypass passage unit 30 at the junction 34. At this time, the refrigerant flowing through the bypass passage portion 30 receives almost no heat from the outside, and thus has a lower temperature than the refrigerant that flows out from the low temperature side heat exchange portion 222 of the internal heat exchanger 22. For this reason, the refrigerant that has flowed out of the low-temperature side heat exchanging part 222 of the internal heat exchanger 22 is merged with the refrigerant that flows through the bypass passage part 30 at the joining part 34, so that the temperature is lowered. That is, the state of the refrigerant shifts from point B6 to point B7 in FIG. Then, the refrigerant that has flowed out from the junction 34 is sucked into the compressor 12 and compressed again. That is, the state of the refrigerant shifts from point B7 in FIG. 5 to point B1.

  As described above, when the discharged refrigerant temperature Td is higher than the open reference temperature Ttho, the refrigerant exerts an endothermic effect in the evaporator 20, thereby cooling the internal air. In addition, the low-temperature refrigerant that has flowed out of the expansion valve 18 flows into the refrigerant suction side of the compressor 12 through the bypass passage 30, whereby the compressor 12 is cooled. Thereby, the temperature of the refrigerant | coolant discharged from the compressor 12 falls.

  Returning to FIG. 3, the control device 50 controls the bypass valve 36 to be in the open state in Step S <b> 40, and then determines whether or not the discharged refrigerant temperature Td is higher than a predetermined closing reference temperature Tthc in Step S <b> 50. The closing reference temperature Tthc is set to a temperature lower than the opening reference temperature Ttho by a predetermined temperature α. The predetermined temperature α is a hysteresis width for preventing hunting of opening and closing of the bypass valve 36.

  When the discharged refrigerant temperature Td is higher than the closing reference temperature Tthc, the control device 50 maintains the bypass valve 36 in the open state in step S40. On the other hand, when the discharged refrigerant temperature Td is equal to or lower than the closing reference temperature Tthc, the control device 50 controls the bypass valve 36 to be closed so that the bypass passage 30 is closed in step S60.

  The refrigeration cycle apparatus 10 of the present embodiment described above is provided with the bypass passage portion 30 for flowing the refrigerant flowing out from the expansion valve 18 to the refrigerant suction side of the compressor 12 and the bypass valve 36 for opening and closing the bypass passage portion 30. . The refrigeration cycle apparatus 10 is configured such that the bypass valve 36 is controlled to be opened by the control device 50 when the discharged refrigerant temperature Td exceeds the open reference temperature Ttho.

  According to this, when the discharged refrigerant temperature Td exceeds the open reference temperature Tthc, the low-temperature refrigerant flowing out from the expansion valve 18 is introduced into the refrigerant suction side of the compressor 12 via the bypass passage portion 30. The compressor 12 is cooled. Thereby, the temperature rise of the refrigerant discharged from the compressor 12 is suppressed.

  Further, since the bypass passage 30 is connected to a portion of the refrigerant outlet side of the expansion valve 18 and the refrigerant suction side of the compressor 12 that are relatively close to each other, the pressure of the refrigerant is reduced with respect to the bypass passage 30. A decompression mechanism becomes unnecessary.

  Therefore, according to the present embodiment, the refrigeration cycle apparatus 10 capable of suppressing the temperature rise of the refrigerant discharged from the compressor 12 can be realized with a compact configuration.

  The refrigeration cycle apparatus 10 of the present embodiment includes an internal heat exchanger 22 that exchanges heat between the refrigerant that has flowed out of the condenser 14 and the refrigerant that has flowed out of the evaporator 20. In the bypass passage portion 30, the refrigerant inflow portion 320 is provided between the refrigerant outlet side of the expansion valve 18 and the refrigerant inlet side of the evaporator 20, and the refrigerant outflow portion 340 is in the low temperature side heat exchange of the internal heat exchanger 22. It is provided between the refrigerant outlet side of the section 222 and the refrigerant suction side of the compressor 12.

  As described above, in the configuration including the internal heat exchanger 22, the enthalpy on the refrigerant outlet side of the condenser 14 is reduced, and the enthalpy difference Δi between the refrigerant outlet side and the refrigerant inlet side of the evaporator 20 is increased. Improvements can be made.

  However, in a configuration that simply includes the internal heat exchanger 22, the temperature of the refrigerant that has flowed out from the low-temperature side heat exchanging unit 222 rises, so the temperature of the refrigerant that is drawn into the compressor 12 rises, and the compressor 12 There is a concern that the cooling effect will decrease.

  On the other hand, in the refrigeration cycle apparatus 10 of the present embodiment, the refrigerant outflow portion 340 of the bypass passage portion 30 is connected between the refrigerant outlet side of the low temperature side heat exchange unit 222 and the refrigerant suction side of the compressor 12. Yes. According to this, since the low-temperature refrigerant that has flowed out of the expansion valve 18 is introduced to the refrigerant suction side of the compressor 12, an increase in the temperature of the refrigerant sucked into the compressor 12 is suppressed. Can be cooled to.

  Therefore, according to the present embodiment, the refrigeration cycle apparatus 10 capable of suppressing the decrease in the refrigeration capacity when suppressing the temperature rise of the refrigerant discharged from the compressor 12 can be realized with a compact configuration.

  Further, in the bypass passage portion 30 of the present embodiment, the refrigerant inflow portion 320 enters the first low pressure passage portion 24 so that the refrigerant having a dryness greater than the dryness of the refrigerant flowing through the first low pressure passage portion 24 flows. It is connected.

  According to this, a refrigerant having a high degree of dryness that does not contribute much to the heat absorption capability in the evaporator 20 flows into the bypass passage portion 30, whereby a liquid-rich refrigerant flows into the evaporator 20. A liquid-rich refrigerant has a smaller pressure loss than a refrigerant having a high degree of dryness, so that the pressure loss in the evaporator 20 is suppressed. When the pressure loss in the evaporator 20 is suppressed, the pressure on the refrigerant outlet side of the evaporator 20 increases, and a high-density refrigerant flows on the refrigerant suction side of the compressor 12. As a result, since the mass flow rate of the refrigerant flowing into the evaporator 20 increases, the refrigerating capacity is improved as compared with the configuration in which the refrigerant having a low dryness flows through the bypass passage portion 30.

  Specifically, the bypass passage 30 is configured such that the flow direction of the refrigerant flowing into the refrigerant inflow portion 320 is higher in the vertical direction DRud than the flow direction of the refrigerant flowing through the branch portion 32 of the first low-pressure passage portion 24. It is connected to the 1st low voltage | pressure channel | path part 24 so that it may become close to the direction which goes to. In this way, by devising a connection mode between the bypass passage 30 and the first low-pressure passage 24, it is possible to flow a refrigerant with a high degree of dryness through the bypass passage. This greatly contributes to downsizing of the refrigeration cycle apparatus 10.

(Modification of the first embodiment)
In the first embodiment described above, an example in which the bypass passage portion 30 is connected to the first low-pressure passage portion 24 so that the flow direction of the refrigerant flowing into the refrigerant inflow portion 320 is directed upward in the vertical direction DRud. However, the present invention is not limited to this.

  The liquid refrigerant has a higher density than the gas refrigerant. For this reason, liquid refrigerant tends to go straight ahead by inertial force compared to gas refrigerant. For example, as shown in FIG. 6, when the first low pressure passage portion 24 includes a bending passage portion 240 that turns the refrigerant flow direction, the liquid refrigerant is an outer wall portion having a large curvature radius in the bending passage portion 240. It becomes easy to flow to 240a. On the contrary, the gas refrigerant easily flows to the inner wall portion 240b having a smaller radius of curvature than the outer wall portion 240a in the bending passage portion 240.

  Focusing on this point, in this modification, as shown in FIG. 6, the refrigerant inflow portion 320 of the bypass passage portion 30 has an inner wall having a smaller radius of curvature than the outer wall portion 240 a on the refrigerant outlet side of the bending passage portion 240. It is connected to a portion that continues to the portion 240b.

  Also in this manner, the gas-liquid two-phase refrigerant that has flowed out of the expansion valve 18 is liable to flow into the first low-pressure passage 24 and the gas-rich refrigerant into the bypass passage 30. For this reason, according to the configuration of the present modification, the refrigerating capacity is improved as compared with the configuration in which the refrigerant having a low dryness flows through the bypass passage portion 30 as in the first embodiment.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. The present embodiment is different from the first embodiment in that an accumulator 28 is added to the refrigeration cycle apparatus 10.

  As shown in FIG. 7, in the refrigeration cycle apparatus 10 of the present embodiment, an accumulator 28 is provided between the refrigerant outlet side of the low temperature side heat exchanging unit 222 of the internal heat exchanger 22 and the refrigerant suction side of the compressor 12. Is provided. The accumulator 28 separates the gas-liquid refrigerant flowing out from the low temperature side heat exchanging section 222 of the internal heat exchanger 22 and causes the gas refrigerant to flow out to the refrigerant suction side of the compressor 12. The accumulator 28 according to the present embodiment is composed of a gas-liquid separator with a liquid storage function for storing a liquid refrigerant that becomes excessive in the cycle.

  In the refrigeration cycle apparatus 10 of the present embodiment, the merging portion 34 is provided on the refrigerant inlet side of the accumulator 28 in the second low-pressure passage portion 26. The refrigerant outflow portion 340 of the bypass passage portion 30 is connected to the junction portion 34. That is, in the bypass passage portion 30 of the present embodiment, the refrigerant outflow portion 340 is connected between the refrigerant outlet side of the low temperature side heat exchanging portion 222 of the internal heat exchanger 22 and the refrigerant inlet side of the accumulator 28.

  Other configurations of the refrigeration cycle apparatus 10 of the present embodiment are the same as those of the first embodiment. The refrigeration cycle apparatus 10 of the present embodiment can obtain the same effects as those of the first embodiment with the same configuration as that of the first embodiment.

  In particular, in the refrigeration cycle apparatus 10 of the present embodiment, the bypass passage portion 30 is connected to the refrigerant inlet side of the accumulator 28. Thus, if the refrigerant outflow portion 340 of the bypass passage 30 is connected to the refrigerant inlet side of the accumulator 28, liquid refrigerant is prevented from being sucked into the compressor 12 (so-called liquid back). Can do.

(Other embodiments)
As mentioned above, although typical embodiment of this invention was described, this invention can be variously deformed as follows, for example, without being limited to the above-mentioned embodiment.

  As in the above-described embodiments, the refrigeration cycle apparatus 10 desirably includes an internal heat exchanger 22 that exchanges heat between the refrigerant flowing out of the condenser 14 and the refrigerant flowing out of the evaporator 20. However, the present invention is not limited to this. The refrigeration cycle apparatus 10 may be configured not to include the internal heat exchanger 22, for example.

  As in each of the above-described embodiments, the bypass passage portion 30 has the refrigerant inflow portion 320 formed of the first low pressure passage portion so that the refrigerant having a dryness larger than the dryness of the refrigerant flowing into the first low pressure passage portion 24 flows. Although it is desirable that the configuration is connected to the device 24, the present invention is not limited to this. In the bypass passage portion 30, for example, the refrigerant inflow portion 320 is connected to the first low pressure passage portion 24 so that the refrigerant having a dryness equal to or smaller than the dryness of the refrigerant flowing through the first low pressure passage portion 24 flows. It may be configured.

  In each of the above-described embodiments, the example in which the refrigeration cycle apparatus 10 of the present invention is applied to a freezer mounted on a trailer or the like has been described, but the present invention is not limited to this. The refrigeration cycle apparatus 10 of the present invention can be applied to various devices such as a vehicle air conditioner that air-conditions a vehicle interior, an air conditioner that air-conditions a house interior, and a hot water supply device that generates hot water.

  In the above-described embodiment, it is needless to say that 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 that it is clearly essential in principle.

  In the above-described 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. Except in some cases, the number is not limited.

  In the above embodiment, when referring to the shape, positional relationship, etc. of the component, etc., the shape, positional relationship, etc. unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to etc.

(Summary)
According to the first aspect shown in a part or all of the above-described embodiments, the refrigeration cycle apparatus is configured so that when the temperature of the refrigerant discharged from the compressor exceeds the open reference temperature, the bypass passage portion is used. Thus, the low-temperature refrigerant flowing out from the expansion valve is introduced to the refrigerant suction side of the compressor.

  According to the second aspect, the refrigeration cycle apparatus includes an internal heat exchanger that exchanges heat between the refrigerant that flows out of the condenser and the refrigerant that flows out of the evaporator. In the bypass passage, the refrigerant inflow portion into which the refrigerant flows is provided between the refrigerant outlet side of the expansion valve and the refrigerant inlet side of the evaporator, and the refrigerant outflow portion from which the refrigerant flows out of the low temperature side heat exchange portion It is provided between the refrigerant outlet side and the refrigerant suction side of the compressor.

  According to a third aspect, the refrigeration cycle apparatus includes an accumulator that separates the gas-liquid refrigerant before being sucked into the compressor and causes the gas refrigerant to flow out to the refrigerant suction side of the compressor. In the bypass passage portion, the refrigerant outflow portion from which the refrigerant flows out is connected to the refrigerant inlet side of the accumulator. Thus, if it is set as the structure which connects the refrigerant | coolant outflow part of a bypass channel part to the refrigerant | coolant inlet side of an accumulator, it can prevent that a liquid refrigerant will be suck | inhaled by a compressor (so-called liquid back | bag).

  According to the fourth aspect, the refrigeration cycle apparatus includes a main refrigerant passage portion that connects the refrigerant outlet side of the expansion valve and the refrigerant inlet side of the evaporator. In the bypass passage portion, the refrigerant inflow portion into which the refrigerant flows is connected to the main refrigerant passage portion so that the refrigerant having a dryness larger than the dryness of the refrigerant flowing in the main refrigerant passage portion flows in.

  According to this, a refrigerant having a high degree of dryness that does not contribute much to the heat absorption capability of the evaporator flows into the bypass passage portion, so that a liquid-rich refrigerant flows to the evaporator. Since the liquid rich refrigerant has a smaller pressure loss than a refrigerant having a high dryness, the pressure loss in the evaporator is suppressed. When the pressure loss in the evaporator is suppressed, the pressure on the refrigerant outlet side of the evaporator increases, and a high-density refrigerant flows on the refrigerant suction side of the compressor. As a result, since the mass flow rate of the refrigerant flowing into the evaporator increases, the refrigerating capacity is improved as compared with the configuration in which the refrigerant having a low dryness flows in the bypass passage portion. The mass flow rate is defined as the mass of the refrigerant that passes through a predetermined surface per unit time.

  Further, according to the fifth aspect, the bypass passage portion of the refrigeration cycle apparatus is such that the flow direction of the refrigerant flowing into the refrigerant inflow portion is higher in the vertical direction than the flow direction of the refrigerant flowing through the main refrigerant passage portion. It is connected to the main refrigerant passage part so that it may become near to the direction which goes to.

  As described above, the refrigerant inflow portion of the bypass passage portion is connected to the main refrigerant passage so that the flow direction of the refrigerant flowing into the refrigerant inflow portion of the bypass passage portion is directed upward in the vertical direction. By doing so, it becomes possible to flow a refrigerant with a large dryness to a bypass channel part.

  Moreover, according to the 6th viewpoint, the refrigeration cycle apparatus is comprised including the bending channel | path part by which the main refrigerant path part turns the flow direction of a refrigerant | coolant. The bypass passage portion is connected to a portion where the refrigerant inflow portion continues to the inner wall portion having a smaller radius of curvature than the outer wall portion on the refrigerant outlet side of the bending passage portion.

  Thus, by connecting the refrigerant inflow portion of the bypass passage portion to the inner wall portion in the bent passage portion of the main refrigerant passage portion, it is possible to flow a refrigerant with a high degree of dryness in the bypass passage portion. Become.

DESCRIPTION OF SYMBOLS 10 Refrigeration cycle apparatus 12 Compressor 14 Condenser 18 Expansion valve 20 Evaporator 30 Bypass passage part 36 Bypass valve (solenoid valve)
500 Solenoid valve controller

Claims (6)

A vapor compression refrigeration cycle apparatus,
A compressor (12) for compressing and discharging the refrigerant;
A condenser (14) for condensing the refrigerant discharged from the compressor;
An expansion valve (18) for expanding the refrigerant flowing out of the condenser;
An evaporator (20) for evaporating the refrigerant flowing out of the expansion valve;
A bypass passage portion (30) for flowing the refrigerant flowing out of the expansion valve to the refrigerant suction side of the compressor, bypassing the evaporator;
An electromagnetic valve (36) for opening and closing the bypass passage portion;
An electromagnetic valve controller (500) for controlling the electromagnetic valve so that the bypass passage is opened when the temperature of the refrigerant discharged from the compressor exceeds a predetermined opening reference temperature;
A refrigeration cycle apparatus comprising: A high temperature side heat exchanging part (221) through which the refrigerant flowing out of the condenser flows and a low temperature side heat exchanging part (222) through which the refrigerant flowing out of the evaporator flows, and the refrigerant flowing through the high temperature side heat exchanging part and An internal heat exchanger (22) for exchanging heat with the refrigerant flowing through the low temperature side heat exchange section,
The bypass passage is provided with a refrigerant inflow portion (320) through which refrigerant flows in between the refrigerant outlet side of the expansion valve and the refrigerant inlet side of the evaporator, and a refrigerant outflow portion (340) through which the refrigerant flows out. 2. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is provided between a refrigerant outlet side of the low-temperature side heat exchange unit and a refrigerant suction side of the compressor. An accumulator (28) that separates the gas-liquid of the refrigerant before being sucked into the compressor and causes the gas refrigerant to flow out to the refrigerant suction side of the compressor;
The refrigeration cycle apparatus according to claim 1 or 2, wherein the bypass passage portion is connected to a refrigerant inlet side of the accumulator at a refrigerant outflow portion (340) through which the refrigerant flows out. A main refrigerant passage portion (24) connecting the refrigerant outlet side of the expansion valve and the refrigerant inlet side of the evaporator;
In the bypass passage portion, a refrigerant inflow portion (320) into which a refrigerant flows is connected to the main refrigerant passage portion so that a refrigerant having a dryness larger than a dryness of the refrigerant flowing in the main refrigerant passage portion flows in. The refrigeration cycle apparatus according to any one of claims 1 to 3.   The bypass passage portion has an upper side in a vertical direction in which a flow direction of the refrigerant flowing into the refrigerant inflow portion is higher than a flow direction of the refrigerant flowing in the connection portion to which the refrigerant inflow portion is connected in the main refrigerant passage portion. The refrigeration cycle apparatus according to claim 4, wherein the refrigeration cycle apparatus is connected to the main refrigerant passage portion so as to be close to a direction toward the center. The main refrigerant passage portion includes a bending passage portion (240) for turning the flow direction of the refrigerant,
The bypass passage portion is connected to a portion where the refrigerant inflow portion is connected to an inner wall portion (240b) having a smaller radius of curvature than an outer wall portion (240a) on the refrigerant outlet side of the bending passage portion. The refrigeration cycle apparatus described.

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