JP2010043754A - Vapor compression type refrigeration cycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor compression type refrigeration cycle sufficiently cooling an invertor by using a sucked refrigerant. <P>SOLUTION: This vapor compression type refrigeration cycle has an electric compressor 10 comprising a compressing section 11 for sucking and compressing a refrigerant, an electric motor 12 driving the compressing section 11, and an invertor 13 operating and controlling the electric motor 12 and cooled by using the sucked refrigerant, an internal heat exchanger 70 exchanging heat between the refrigerant flowing in a high temperature side flow channel 71 and the refrigerant flowing in a low temperature side flow channel 72, a bypass circuit 80 branched from a main refrigerant circuit 20 at a downstream side with respect to an evaporator 50 so that the refrigerant flows therein while bypassing the low temperature side flow channel 72, a flow channel switching valve 90 switching the refrigerant flow channel between the main refrigerant circuit 20 and the bypass circuit 80, a temperature sensor 110 detecting an invertor temperature Tinv, and a control device 100 controlling the flow channel switching valve 90 based on the temperature Tinv. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vapor compression refrigeration cycle.

Conventionally, for example, as disclosed in Patent Document 1, a compressor mechanism unit that compresses and discharges the sucked refrigerant, an electric motor that drives the compressor mechanism unit, and an inverter that controls the operation of the electric motor are provided. An electric compressor that cools an inverter using a suction refrigerant is known. The low-pressure refrigerant flowing into the electric compressor passes through the cooling space in the inverter case and is sucked into the compressor mechanism after the inverter is cooled.
US Pat. No. 7,179,068

  By the way, in a vapor compression refrigeration cycle in which an electric compressor, a gas cooler, an expansion valve, and an evaporator are sequentially connected in an annular manner, a high-pressure refrigerant that is downstream of the gas cooler and upstream of the expansion valve, and downstream of the evaporator In some cases, an internal heat exchanger that performs heat exchange with the low-pressure refrigerant upstream of the electric compressor may be provided. By providing the internal heat exchanger, the enthalpy difference between the evaporator inlet and outlet can be increased, so that the refrigeration capacity of the refrigeration cycle can be improved.

  However, if the internal heat exchanger is provided in the refrigeration cycle using the electric compressor as described above, the temperature of the low-pressure refrigerant flowing into the electric compressor rises, so that the inverter cannot be sufficiently cooled, and the electric compressor May stop functioning.

  An object of the present invention is to provide a vapor compression refrigeration cycle capable of sufficiently cooling an inverter using an intake refrigerant.

  In order to achieve the above object, the present invention employs the following technical means.

  The invention according to claim 1 controls the operation of the compressor (11) for sucking in and compressing the refrigerant, the electric motor (12) for driving the compressor (11), and the electric motor (12), and the sucked refrigerant. An electric compressor (10) having an inverter (13) to be cooled using, a gas cooler (30) for cooling the refrigerant compressed by the electric compressor (10), and a refrigerant cooled by the gas cooler (30) A decompression means (40) for decompressing, an evaporator (50) for evaporating the refrigerant decompressed by the decompression means (40) and returning it to the electric compressor (10), and a decompression means (on the downstream side of the gas cooler (30)) 40) a high temperature side flow path (71) located upstream from the evaporator, and a low temperature side flow path (72) located downstream from the evaporator (50) and upstream from the electric compressor (10). A refrigerant flowing through the high temperature side channel (71) and a low temperature An internal heat exchanger (70) for exchanging heat with the refrigerant flowing in the flow path (72), an electric compressor (10), a gas cooler (30), a high temperature side flow path (71), and a pressure reducing means (40). The evaporator (50) and the low-temperature side flow path (72) are connected in a ring shape, and the main refrigerant circuit (20) for circulating the refrigerant is branched from the main refrigerant circuit (20) on the downstream side of the evaporator (50). The bypass circuit (80) for flowing the refrigerant bypassing the low temperature side flow path (72), and the flow path switching means (90) for switching the refrigerant flow path between the main refrigerant circuit (20) and the bypass circuit (80). ), Temperature detection means (110) for detecting the temperature (Tinv) of the inverter (13), and control means (100) for controlling the flow path switching means (90) based on the temperature (Tinv). It is a featured vapor compression refrigeration cycle.

  Thus, the refrigerant flow path is switched between the bypass circuit (80) and the main refrigerant circuit (20) based on the temperature (Tinv) of the inverter (13), and the low temperature side flow path ( 72) can be bypassed, the temperature of the refrigerant sucked into the electric compressor (10) can be maintained at a relatively low temperature. Therefore, the inverter (13) can be sufficiently cooled using the suction refrigerant.

  The invention according to claim 2 is characterized in that the bypass circuit (80) is joined to the main refrigerant circuit (20) on the upstream side of the electric compressor (10).

  Thereby, since the refrigerant | coolant piping connected to the suction side of an electric compressor (10) can be made into one, the electric compressor (10) provided with only one refrigerant | coolant inlet can be used as it is.

  According to a third aspect of the present invention, the electric compressor (15) includes a first passage (16) for circulating the sucked refrigerant to cool the inverter (13), and a first passage (16) for the sucked refrigerant. A second passage (17) that is sent to the compression section (11) without passing through, the main refrigerant circuit (21) is connected to the second passage (17), and the bypass circuit (82) is the first passage. It is connected to (16).

  Thereby, the refrigerant flowing through the bypass circuit (82) is sucked into the electric compressor (15) at a low temperature without being mixed with the refrigerant heated through the low-temperature side flow path (72), and is then passed through the first passage. Since (16) is distributed, the cooling efficiency of the inverter (13) can be improved.

  According to a fourth aspect of the present invention, when the temperature (Tinv) is lower than the predetermined temperature (T0), the control means (100) closes the bypass circuit (80) side and opens the main refrigerant circuit (20) side. The flow path switching means (90) is controlled so that when the temperature (Tinv) is equal to or higher than the predetermined temperature (T0), the bypass circuit (80) side is opened and the main refrigerant circuit (20) side is closed. Thus, the flow path switching means (90) is controlled.

  Thereby, the control of the flow path switching means (90) by the control means (100) can be a relatively simple two-position control.

  According to the fifth aspect of the present invention, the flow path switching means (90) is capable of adjusting a flow rate ratio between the refrigerant flowing through the low temperature side flow path (72) and the refrigerant flowing through the bypass circuit (80). (100) is characterized in that the flow path switching means (90) is controlled such that the flow rate ratio of the refrigerant flowing through the bypass circuit (80) increases as the temperature (Tinv) increases.

  Thereby, since the temperature of the suction | inhalation refrigerant | coolant of an electric compressor (10) can be made low, so that the temperature (Tinv) of an inverter (13) is high, an inverter (13) can fully be cooled. Moreover, since the flow rate ratio of the refrigerant | coolant which flows through a low temperature side flow path (72) can be made so high that the temperature (Tinv) of an inverter (13) is low, heat exchange with a high voltage | pressure refrigerant | coolant is carried out in an internal heat exchanger (70). And the refrigeration capacity of the vapor compression refrigeration cycle can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each said means has shown an example of the corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a configuration of a vapor compression refrigeration cycle in the present embodiment. The vapor compression refrigeration cycle of the present embodiment constitutes, for example, a vehicle air conditioner mounted on a vehicle, and CO ₂ refrigerant is used as a refrigerant circulating inside. As shown in FIG. 1, the electric compressor 10, the gas cooler 30, the expansion valve 40, the evaporator 50, and the accumulator 60 have the main refrigerant circuit 20 connected cyclically | annularly via refrigerant piping. In the vapor compression refrigeration cycle, heat exchange is performed between the high-pressure refrigerant flowing between the gas cooler 30 and the expansion valve 40 in the main refrigerant circuit 20 and the low-pressure refrigerant flowing between the evaporator 50 and the electric compressor 10. An internal heat exchanger 70 for performing the above is provided.

  The electric compressor 10 is operated by, for example, a scroll-type compression unit 11 that compresses and discharges the sucked low-pressure refrigerant to high temperature and high pressure, an electric motor 12 that rotationally drives the compression unit 11, and supplies electric power to the electric motor 12. And an inverter 13 to be controlled. The inverter 13 has a large number of semiconductor elements, and controls power supplied to the electric motor 12 based on control signals from the control device 100. As a result, the electric compressor 10 is driven at a variable rotational speed corresponding to the heat load under the control of the control device 100.

  Since the electric compressor 10 is disposed in the engine room or the like, the inverter 13 becomes high temperature due to its own heat generation or the ambient temperature in the engine room. In order to prevent malfunction due to temperature rise, the inverter 13 is cooled by using a low-pressure refrigerant sucked into the electric compressor 10. That is, a refrigerant passage for cooling the inverter 13 is formed in the electric compressor 10 so that the sucked refrigerant passes through the periphery of the inverter 13 and then is sent to the compressor 11 side. Further, on the circuit board of the inverter 13, for example, a temperature sensor (temperature detection means) 110 that detects the inverter temperature Tinv and outputs a detection signal to the control device 100 is provided.

  A gas cooler 30 is provided on the downstream side of the refrigerant flow of the electric compressor 10. The gas cooler 30 is a heat exchanger that radiates and cools the high-pressure refrigerant discharged from the electric compressor 10 by heat exchange with outside air that is forcibly blown by a blower (not shown). A high-temperature channel 71 of the internal heat exchanger 70 is provided on the downstream side of the refrigerant flow of the gas cooler 30.

  An expansion valve 40 is provided on the downstream side of the refrigerant flow in the high temperature side channel 71. The expansion valve 40 is a decompression unit that decompresses and expands the high-pressure refrigerant cooled by the gas cooler 30. For example, the expansion valve 40 is a temperature type expansion valve that controls the throttle opening so that the degree of refrigerant superheating on the outlet side of the gas cooler 30 becomes a predetermined value. As the pressure reducing means, a fixed throttle such as a fixed orifice tube or capillary can be used instead of the expansion valve 40.

  An evaporator 50 is provided on the downstream side of the refrigerant flow of the expansion valve 40. The evaporator 50 is a heat exchanger (heat absorber) that evaporates the refrigerant flowing through the inside by heat exchange with air. The evaporator 50 is arrange | positioned, for example in the air-conditioning case of a vehicle air conditioner, and absorbs heat from the conditioned air forcedly ventilated.

  An accumulator 60 is provided on the downstream side of the refrigerant flow of the evaporator 50. The accumulator 60 is a gas-liquid separator that separates the refrigerant flowing out of the evaporator 50 into a gas-phase refrigerant and a liquid-phase refrigerant and causes the gas-phase refrigerant to flow out. A low temperature side flow path 72 of the internal heat exchanger 70 is provided on the downstream side of the accumulator 60 in the main refrigerant circuit 20.

  Further, a bypass circuit 80 that branches from the main refrigerant circuit 20 and bypasses the low temperature side flow path 72 is provided on the downstream side of the refrigerant flow of the accumulator 60. The bypass circuit 80 joins the main refrigerant circuit 20 at a junction 81 at a downstream side of the low temperature side flow path 72 and an upstream side of the electric compressor 10.

  At a branch point between the main refrigerant circuit 20 and the bypass circuit 80, a flow path switching valve (flow path switching means) 90 that is operated and controlled by the control device 100 and switches the refrigerant flow path is provided. In the present embodiment, an electromagnetic valve having a three-way valve structure is used as the flow path switching valve 90. For example, when the flow path switching valve 90 is not energized, the main refrigerant circuit 20 (low temperature side flow path 72) side is opened, and the bypass circuit 80 side is closed. When power is supplied from the control device 100 to the flow path switching valve 90, the flow path is switched, the low temperature side flow path 72 side is closed, and the bypass circuit 80 side is opened.

  The control device (control means) 100 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. Various control signals from an operation panel (not shown), detection signals from various sensor groups including the temperature sensor 110, and the like are input to the control device 100. The control device 100 controls the operation of various devices such as the electric compressor 10 and the flow path switching valve 90 based on these input signals.

  Here, the control procedure of the flow path switching valve 90 in the control device 100 will be described. FIG. 2 is a flowchart illustrating an example of a control procedure of the flow path switching valve 90 executed by the control device 100. As shown in FIG. 2, the control device 100 first acquires the inverter temperature Tinv based on the detection signal input from the temperature sensor 110 (step S1).

  Next, the control device 100 reads a preset set temperature T0 from the ROM, and compares the acquired inverter temperature Tinv with the set temperature T0 (step S2). If it is determined that the inverter temperature Tinv is lower than the set temperature T0 (Tinv <T0), the process proceeds to step S3. In step S3, if the flow path switching valve 90 is in a non-energized state, that state is maintained, and if it is in an energized state, energization is stopped. Thereby, the flow path switching valve 90 is closed on the bypass circuit 80 side and opened on the low temperature side flow path 72 side. Therefore, the entire amount of the gas-phase refrigerant flowing out from the accumulator 60 is heated by heat exchange with the high-pressure refrigerant through the low temperature side flow path 72 and sucked into the electric compressor 10.

  On the other hand, if it is determined in step S2 that the inverter temperature Tinv is equal to or higher than the set temperature T0 (Tinv ≧ T0), the process proceeds to step S4. In step S4, energization is started if the flow path switching valve 90 is in a non-energized state, and is maintained in an energized state. Thereby, the flow path switching valve 90 is opened on the bypass circuit 80 side and closed on the low temperature side flow path 72 side. Therefore, the entire amount of the gas-phase refrigerant flowing out of the accumulator 60 passes through the bypass circuit 80 bypassing the low-temperature side flow path 72 and is sucked into the electric compressor 10 without being heated by heat exchange with the high-pressure refrigerant. The

  The above steps S1 to S4 are repeated every predetermined time until the operation of the refrigeration cycle is completed (step S5).

  FIG. 3 is a graph showing an example of the relationship between the inverter temperature Tinv and the operation of the flow path switching valve 90 in the present embodiment. The horizontal axis of the graph represents the inverter temperature Tinv, and the vertical axis represents the open / closed state of the flow path switching valve 90 on the bypass circuit 80 side. As shown in FIG. 3, when the inverter temperature Tinv is lower than the set temperature T0, the bypass circuit 80 side of the flow path switching valve 90 is in the closed state, and the low temperature side flow path 72 side is in the open state. When the inverter temperature Tinv is equal to or higher than the set temperature T0, the bypass circuit 80 side of the flow path switching valve 90 is opened, and the low temperature side flow path 72 side is closed.

  Next, the operation of the vapor compression refrigeration cycle of this embodiment will be described.

  When an air conditioning operation signal, a set temperature signal, or the like is input to the control device 100 by an occupant's operation, the control device 100 outputs a start signal to the inverter 13 of the electric compressor 10. Thereby, electric power is supplied to the electric motor 12 via the inverter 13, and the compression part 11 starts the rotational drive by predetermined rotation speed. The compressor 11 sucks and compresses the gas-phase refrigerant, and discharges the high-temperature and high-pressure refrigerant with a predetermined discharge capacity.

  The high-temperature and high-pressure refrigerant discharged from the electric compressor 10 flows into the gas cooler 30 through the refrigerant pipe. The high-temperature and high-pressure refrigerant that has flowed into the gas cooler 30 is cooled by heat exchange with the outside air of the passenger compartment. The high-pressure refrigerant that has flowed out of the gas cooler 30 passes through the high-temperature side passage 71 of the internal heat exchanger 70 and is further cooled by heat exchange with the low-pressure refrigerant that passes through the low-temperature side passage 72. The high-pressure refrigerant that has flowed out of the high-temperature channel 71 flows into the expansion valve 40.

  The high-pressure refrigerant that has flowed into the expansion valve 40 passes through a throttle passage in the expansion valve 40 and is throttled and expanded to become a gas-liquid two-phase low-pressure refrigerant. The low-pressure refrigerant that has flowed out of the expansion valve 40 flows into the evaporator 50. The low-pressure refrigerant that has flowed into the evaporator 50 absorbs heat from the conditioned air blown by the blower fan.

  The low-pressure refrigerant that has flowed out of the evaporator 50 flows into the accumulator 60 and undergoes gas-liquid separation, and only the gas-phase refrigerant flows out of the accumulator 60. The gas-phase refrigerant passes through the flow path selected by the flow path switching valve 90 and is sucked into the electric compressor 10. That is, when the inverter temperature Tinv is lower than the set temperature T0, the low temperature side flow path 72 side of the flow path switching valve 90 is in an open state, so that the gas phase refrigerant flows through the low temperature side flow path 72. As a result, the gas-phase refrigerant is heated by heat exchange with the high-pressure refrigerant flowing through the high-temperature side flow path 71 in the internal heat exchanger 70, becomes relatively high temperature, and is sucked into the electric compressor 10. The gas-phase refrigerant flowing into the electric compressor 10 is compressed and discharged again by the compressor 11 after the inverter 13 is cooled.

  When the inverter temperature Tinv rises due to its own heat generation or the ambient temperature in the engine room and exceeds the set temperature T0, the flow path is switched under the control of the control device 100, and the bypass circuit 80 side of the flow path switching valve 90 is opened. Become. As a result, the gas-phase refrigerant that has flowed out of the accumulator 60 bypasses the low-temperature side flow path 72 and flows through the bypass circuit 80, and is not heated by heat exchange with the high-pressure refrigerant. Inhaled. The low-temperature gas-phase refrigerant that has flowed into the electric compressor 10 is compressed and discharged again by the compressor 11 after the inverter 13 is cooled.

  When the inverter 13 is cooled by the low-temperature suction refrigerant and the inverter temperature Tinv falls below the set temperature T0, the flow path is switched again by the control of the control device 100, and the low temperature side flow path 72 side of the flow path switching valve 90 is opened. Become. Thereby, heat exchange between the high-pressure refrigerant and the low-pressure refrigerant in the internal heat exchanger 70 is resumed.

  As described above, according to the present embodiment, the refrigerant flow path can be switched between the bypass circuit 80 and the main refrigerant circuit 20 by controlling the flow path switching valve 90 based on the inverter temperature Tinv. When the inverter temperature Tinv is high, the low-pressure refrigerant can flow to the bypass circuit 80 side by bypassing the low-temperature side flow path 72 of the internal heat exchanger 70. The low-pressure refrigerant flowing through the bypass circuit 80 is sucked into the electric compressor 10 at a low temperature without being heated by heat exchange with the high-pressure refrigerant. Therefore, the inverter 13 can be sufficiently cooled using the suction refrigerant. Thereby, the function stop of the electric compressor 10 due to the temperature rise of the inverter 13 can be avoided.

  On the other hand, when the inverter temperature Tinv is low, the low-pressure refrigerant can flow through the low-temperature side flow path 72, so that heat exchange between the high-pressure refrigerant and the low-pressure refrigerant can be performed in the internal heat exchanger 70. Therefore, since the enthalpy difference between the evaporator 50 inlet and outlet can be increased, the refrigeration capacity of the vapor compression refrigeration cycle can be improved.

  In the present embodiment, the bypass circuit 80 is joined to the main refrigerant circuit 20 on the upstream side of the electric compressor 10, so that one refrigerant pipe connected to the suction side of the electric compressor 10 can be used. it can. Therefore, the electric compressor 10 having a conventional structure having only one refrigerant suction port can be used as it is.

  Furthermore, in this embodiment, since the control of the flow path switching valve 90 is a relatively simple two-position control, it is possible to suppress an increase in the cost of the vapor compression refrigeration cycle.

  Here, in this embodiment, when the temperature of the inverter 13 rises and the refrigerant flow path is switched to the bypass circuit 80 side, heat exchange between the high-pressure refrigerant and the low-pressure refrigerant in the internal heat exchanger 70 is performed. Therefore, the refrigeration capacity of the electric compressor 10 may be temporarily reduced. However, in this embodiment, since the operation of the electric compressor 10 is continued even during this period, the influence is less than when the function of the electric compressor 10 is stopped until the temperature of the inverter 13 decreases.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The vapor compression refrigeration cycle of the present embodiment has the same configuration as the vapor compression refrigeration cycle shown in FIG. 1 except that an electric three-way valve capable of proportional control is used as the flow path switching valve 90. is doing. The flow path switching valve 90 can adjust the flow rate ratio of the refrigerant flowing on the low temperature side flow path 72 side and the refrigerant flowing on the bypass circuit 80 side in a multistage or stepless manner from 0:10 to 10: 0, for example. The control device 100 controls the flow path switching valve 90 based on the inverter temperature Tinv and the first and second preset temperatures T1 and T2 (T1 <T2) set in advance as follows, and the flow rate ratio of the refrigerant Is to control.

  FIG. 4 is a graph showing an example of the relationship between the inverter temperature Tinv and the operation of the flow path switching valve 90 in the present embodiment. The horizontal axis of the graph represents the inverter temperature Tinv, and the vertical axis represents the opening degree of the flow path switching valve 90 on the bypass circuit 80 side. As shown in FIG. 4, when the inverter temperature Tinv is lower than the first set temperature T1 (Tinv <T1), the opening degree of the flow path switching valve 90 on the bypass circuit 80 side is 0% by the control device 100. Set to Thus, the entire amount of the low-pressure refrigerant flows through the low-temperature side flow path 72 of the internal heat exchanger 70, is heated by heat exchange with the high-pressure refrigerant, and is sucked into the electric compressor 10.

  When the inverter temperature Tinv is equal to or higher than the first set temperature T1 and lower than the second set temperature T2 (T1 ≦ Tinv <T2), the opening degree of the flow path switching valve 90 on the bypass circuit 80 side is equal to the inverter temperature Tinv. It is set so as to increase almost linearly from 0% to 100% as it rises. Thus, the low-pressure refrigerant flows through the low temperature side flow path 72 at a higher flow rate ratio as the inverter temperature Tinv is lower, and flows through the bypass circuit 80 at a higher flow rate ratio as the inverter temperature Tinv is higher. The low-pressure refrigerant flowing in the low-temperature side flow path 72 is heated by heat exchange with the high-pressure refrigerant and travels toward the junction 81. The low-pressure refrigerant flowing through the bypass circuit 80 goes to the junction 81 at a low temperature. In the merging portion 81, the refrigerant heated through the low temperature side flow path 72 and the low temperature refrigerant flowing through the bypass circuit 80 are mixed at a predetermined flow rate ratio and sucked into the electric compressor 10. The temperature of the refrigerant sucked into the electric compressor 10 is higher as the inverter temperature Tinv is lower, and is lower as the inverter temperature Tinv is higher.

  When the inverter temperature Tinv is equal to or higher than the second set temperature T2 (Tinv ≧ T2), the opening degree of the flow path switching valve 90 on the bypass circuit 80 side is set to 100%. As a result, the entire amount of the low-pressure refrigerant flows through the bypass circuit 80 and is sucked into the electric compressor 10 at a low temperature.

  According to this embodiment, the temperature of the suction refrigerant of the electric compressor 10 is adjusted based on the inverter temperature Tinv, and the higher the inverter temperature Tinv, the lower the temperature of the suction refrigerant. Can be cooled.

  Moreover, since the flow rate ratio of the refrigerant flowing through the low temperature side flow path 72 can be increased as the inverter temperature Tinv is lower, as much refrigerant as possible flows through the low temperature side flow path 72 within a range in which the inverter 13 can be cooled. Can do. Thereby, heat exchange between the high-pressure refrigerant and the low-pressure refrigerant can be performed in the internal heat exchanger 70. Therefore, since the enthalpy difference between the evaporator 50 inlet and outlet can be increased, the refrigeration capacity of the vapor compression refrigeration cycle can be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 shows the configuration of the vapor compression refrigeration cycle in the present embodiment. As shown in FIG. 5, in the present embodiment, the electric compressor 15 cools the inverter 13 by circulating the refrigerant sucked from the two refrigerant suction ports 18 and 19 and the one refrigerant suction port 18. 16 and a second passage 17 for sending the refrigerant sucked from the other refrigerant suction port 19 to the compression unit 11 without passing through the first passage 16. The first passage 16 merges with the second passage 17 on the downstream side, and the refrigerant flowing through the first passage 16 is sent to the compression unit 11 through the second passage 17. The refrigerant sucked from the refrigerant suction port 18 directly flows through the first passage 16 and contributes directly to the cooling of the inverter 13, whereas the refrigerant sucked from the refrigerant suction port 19 does not flow through the first passage 16. Therefore, it does not directly contribute to cooling of the inverter 13.

  In the present embodiment, the main refrigerant circuit 21 is connected to the refrigerant suction port 19, and the bypass circuit 82 that branches from the main refrigerant circuit 21 and bypasses the low-temperature side flow path 72 is joined to the main refrigerant circuit 21. Instead, it is directly connected to the refrigerant inlet 18 of the electric compressor 15.

  An electric three-way valve capable of proportional control is provided as a flow path switching valve 90 at a branch portion between the main refrigerant circuit 21 and the bypass circuit 82. The flow path switching valve 90 is controlled by the control device 100 according to the inverter temperature Tinv based on, for example, the relationship shown in FIG.

  In the present embodiment, the downstream end of the bypass circuit 82 is directly connected to the electric compressor 15. Therefore, when the flow path switching valve 90 is controlled to the intermediate opening and the refrigerant flows through both the bypass circuit 82 and the low temperature side flow path 72, the refrigerant that has passed through the bypass circuit 82 passes through the low temperature side flow path 72. The refrigerant flows into the first passage 16 of the electric compressor 15 at a low temperature without being mixed with the heated refrigerant. Therefore, since the temperature difference between the suction refrigerant flowing through the first passage 16 and the inverter 13 can be increased, the cooling efficiency of the inverter 13 can be improved.

(Other embodiments)
In the said embodiment, although the electric compressors 10 and 15 with which the inverter 13 was integrated were mentioned as an example, the inverter may be a different body from the electric compressor main body.

In the above embodiment, although exemplified the CO ₂ refrigerant as an example, it is also possible to use fluorocarbon refrigerant, other refrigerants such as HC refrigerants.

  Further, in the first and second embodiments, the example in which the flow path switching valve 90 is provided at the branch portion between the main refrigerant circuit 20 and the bypass circuit 80 is described. However, the flow path switching valve is provided in the merging section 81. You can also.

  Moreover, in the said embodiment, although the flow-path switching valve 90 of the three-way valve structure was mentioned as an example as a flow-path switching means, if a flow path can be switched between the main refrigerant circuit 20 and the bypass circuits 80 and 82, it will be different. A configuration can be used. For example, the main refrigerant circuit 20 (on the downstream side of the branching portion with the bypass circuits 80 and 82) and the bypass circuits 80 and 82 may be provided with flow control valves (or shut-off valves) having a two-way valve structure, respectively.

  Furthermore, although the example which provided the temperature sensor 110 on the circuit board of the inverter 13 was given in the said embodiment, the temperature sensor 110 should just be provided in the position which can detect the temperature of the inverter 13 vicinity.

  In the first embodiment, the threshold value of the inverter temperature Tinv is set to only the set temperature T0. However, in order to prevent the hunting operation of the flow path switching valve 90, the threshold temperature when the inverter temperature Tinv rises is set. You may set higher than the threshold temperature when inverter temperature Tinv falls.

It is a figure which shows the structure of the vapor compression refrigeration cycle in 1st Embodiment. It is a flowchart which shows an example of the control procedure of the flow-path switching valve performed by a control apparatus. It is a graph which shows an example of the relationship between inverter temperature Tinv and operation | movement of a flow-path switching valve in 1st Embodiment. It is a graph which shows an example of the relationship between inverter temperature Tinv and operation | movement of a flow-path switching valve in 2nd Embodiment. It is a figure which shows the structure of the vapor compression refrigeration cycle in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 15 Electric compressor 11 Compression part 12 Electric motor 13 Inverter 16 1st channel | path 17 2nd channel | path 20, 21 Main refrigerant circuit 30 Gas cooler 40 Expansion valve (pressure reduction means)
50 Evaporator 70 Internal Heat Exchanger 71 High Temperature Side Channel 72 Low Temperature Side Channel 80, 82 Bypass Circuit 90 Channel Switching Valve (Channel Switching Unit)
100 Control device (control means)
110 Temperature sensor (temperature detection means)

Claims (5)

A compressor (11) that sucks and compresses the refrigerant, an electric motor (12) that drives the compressor (11), and an inverter that controls the operation of the electric motor (12) and is cooled using the sucked refrigerant ( 13) an electric compressor (10) provided with;
A gas cooler (30) for cooling the refrigerant compressed by the electric compressor (10);
Decompression means (40) for decompressing the refrigerant cooled by the gas cooler (30);
An evaporator (50) for evaporating the refrigerant decompressed by the decompression means (40) and returning it to the electric compressor (10);
A high-temperature channel (71) positioned downstream of the gas cooler (30) and upstream of the decompression means (40), and the electric compressor (10) downstream of the evaporator (50) And a low-temperature channel (72) positioned upstream from the inside, and performs heat exchange between the refrigerant flowing through the high-temperature channel (71) and the refrigerant flowing through the low-temperature channel (72). A heat exchanger (70);
The electric compressor (10), the gas cooler (30), the high temperature side flow path (71), the pressure reducing means (40), the evaporator (50) and the low temperature side flow path (72) are connected in an annular shape. A main refrigerant circuit (20) for circulating the refrigerant;
A bypass circuit (80) that branches from the main refrigerant circuit (20) downstream of the evaporator (50) and flows the refrigerant bypassing the low-temperature side flow path (72);
Flow path switching means (90) for switching a refrigerant flow path between the main refrigerant circuit (20) and the bypass circuit (80);
Temperature detecting means (110) for detecting the temperature (Tinv) of the inverter (13);
A vapor compression refrigeration cycle comprising control means (100) for controlling the flow path switching means (90) based on the temperature (Tinv).   The vapor compression refrigeration cycle according to claim 1, wherein the bypass circuit (80) joins the main refrigerant circuit (20) upstream of the electric compressor (10). The electric compressor (15) includes a first passage (16) for circulating the sucked refrigerant to cool the inverter (13), and the compression of the sucked refrigerant without passing through the first passage (16). A second passage (17) for sending to the part (11),
The main refrigerant circuit (21) is connected to the second passage (17),
The vapor compression refrigeration cycle according to claim 1, wherein the bypass circuit (82) is connected to the first passage (16). The control means (100)
When the temperature (Tinv) is lower than a predetermined temperature (T0), the flow path switching means (90) is set so that the bypass circuit (80) side is closed and the main refrigerant circuit (20) side is opened. Control
When the temperature (Tinv) is equal to or higher than the predetermined temperature (T0), the flow path switching means (90) is configured such that the bypass circuit (80) side is opened and the main refrigerant circuit (20) side is closed. The vapor compression refrigeration cycle according to any one of claims 1 to 3, wherein the refrigeration cycle is controlled. The flow path switching means (90) is capable of adjusting a flow rate ratio between the refrigerant flowing through the low temperature side flow path (72) and the refrigerant flowing through the bypass circuit (80).
The control means (100) controls the flow path switching means (90) so that the flow rate ratio of the refrigerant flowing through the bypass circuit (80) increases as the temperature (Tinv) increases. The vapor compression refrigeration cycle according to any one of claims 1 to 3.

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