JP6191518B2 - Vapor compression refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a vapor compression refrigeration cycle apparatus applied to an air conditioner.

  Conventionally, a vapor compression refrigeration cycle apparatus applied to an air conditioner that performs air conditioning of an air-conditioning target space is known, for example, as disclosed in Patent Document 1. The vapor compression refrigeration cycle apparatus disclosed in Patent Document 1 performs heat exchange between the compressor that compresses and discharges the refrigerant, and the blown air that is blown into the air-conditioning target space and the refrigerant, and radiates heat from the refrigerant. A heat exchanger, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, an indoor evaporator that evaporates the refrigerant by exchanging heat between the blown air and the refrigerant before passing through the indoor radiator, A first expansion valve that decompresses and expands the refrigerant flowing into the outdoor heat exchanger, and a second expansion valve that decompresses and expands the refrigerant that flows into the indoor evaporator.

  Furthermore, the vapor compression refrigeration cycle apparatus includes a switching valve that opens and closes between the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the compressor, and the refrigerant that has passed through one of the switching valve and the indoor evaporator is gas-liquid separated. And an accumulator for guiding the gas refrigerant to the refrigerant inlet of the compressor.

  In the vapor compression refrigeration cycle apparatus, in the heating mode, the second expansion valve is closed and the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the indoor evaporator are closed and discharged from the compressor. The refrigerant is returned to the compressor by flowing in the order of the indoor radiator, first expansion valve, outdoor heat exchanger, switching valve, and accumulator. For this reason, the air which passed the indoor heat radiator can be heated with a refrigerant | coolant, and a warm air can be blown into the air-conditioning object space.

JP 2012-225637 A

  In the vapor compression refrigeration cycle apparatus, in the heating mode, the second expansion valve is closed and the space between the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the indoor evaporator is closed. Immediately after closing the second expansion valve to start the heating mode, the refrigerant pressure in the indoor evaporator becomes lower than the refrigerant pressure on the refrigerant inlet side of the accumulator, and the refrigerant inlet side of the accumulator In some cases, the refrigerant flows into the indoor evaporator. In particular, when the indoor evaporator is disposed at a position lower than the accumulator, the refrigerant easily flows from the refrigerant inlet side of the accumulator into the indoor evaporator.

  Here, the refrigerant contains lubricating oil in order to lubricate mechanisms such as a compressor bearing and a compression mechanism. For this reason, lubricating oil may accumulate in the indoor evaporator by flowing into the indoor evaporator from the refrigerant inlet side of the accumulator as the heating mode is performed. Therefore, there is a possibility that the lubricating oil that should be supplied to the compressor is insufficient.

  In view of the above points, an object of the present invention is to provide a vapor compression refrigeration cycle apparatus in which lubricating oil that accumulates in an evaporator as the heating mode is performed is returned to the compressor side.

In order to achieve the above object, in the first aspect of the present invention, heat is generated between the compressor (11) that compresses and discharges the refrigerant containing the lubricating oil, and the blown air blown into the air-conditioning target space and the refrigerant. Heat is exchanged between the radiator (12) that is exchanged and dissipates heat from the refrigerant, the outdoor heat exchanger (15) that exchanges heat between the refrigerant and the outside air, and the blown air and refrigerant before passing through the radiator. The outdoor heat exchanger is disposed between the evaporator (20) for evaporating the refrigerant by exchanging the refrigerant and flowing the refrigerant to the suction side of the compressor, and the refrigerant outlet of the radiator and the refrigerant inlet of the outdoor heat exchanger. A first expansion valve (14) that decompresses and expands the refrigerant flowing into the refrigerant, an on-off valve (19) that opens and closes between the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the evaporator, the refrigerant outlet of the outdoor heat exchanger, and Close the space between the refrigerant inlets of the evaporator with an open / close valve. A determination means (S110) for determining whether or not the heating mode in which the discharged refrigerant is flowed in the order of the radiator, the first expansion valve, and the outdoor heat exchanger and returning to the compressor is performed for a certain period, and the heating mode When the determination means determines that it has been carried out for a certain period of time, it opens an opening / closing valve between the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the evaporator, and flows the refrigerant discharged from the compressor to the radiator, And the control means (S120) which implements the oil return mode which returns the refrigerant | coolant of the refrigerant | coolant flow downstream of a radiator to the compressor by flowing in order of an on-off valve and an evaporator,
A bypass passage (22) for allowing the refrigerant on the downstream side of the refrigerant flow of the radiator to bypass the outdoor heat exchanger and flow to the inlet side of the on-off valve;
A first switching valve (23) for opening and closing the bypass passage,
In the oil return mode, the control means opens the bypass passage by the first switching valve while flowing the refrigerant discharged from the compressor in the order of the radiator, the first expansion valve, and the outdoor heat exchanger and returning it to the compressor. The refrigerant discharged from the compressor flows in the order of the radiator, the bypass passage, the first switching valve, the on-off valve, and the evaporator, and is returned to the compressor .

  Therefore, according to the first aspect of the present invention, the heating mode is implemented by performing the oil return mode in which the refrigerant on the downstream side of the refrigerant flow of the radiator flows in the order of the on-off valve and the evaporator and returns to the compressor. Accordingly, the lubricating oil accumulated in the evaporator can be returned to the compressor side.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a schematic block diagram of the vehicle air conditioner which concerns on 1st Embodiment of this invention. It is a flowchart which shows the control processing of the electronic controller of FIG. It is a figure which shows control states, such as a switching valve required for the heating mode of 1st Embodiment, and an oil return mode. It is a timing chart which shows the operating state of a switching valve, the operating state of an expansion valve, and an oil circulation rate in the heating mode and oil return mode of a 1st embodiment. It is a graph which shows the requirements for determining the oil return operation time (DELTA) t of 1st Embodiment, and the throttle opening of a 2nd expansion valve. It is a figure which shows the control states of the switching valve etc. which are required for the heating mode of 2nd Embodiment of this invention, and an oil return mode. It is a schematic block diagram of the vehicle air conditioner which concerns on 2nd Embodiment. It is a timing chart which shows the operating state of a change valve, the operating state of an expansion valve, and the oil circulation rate in the heating mode and oil return mode of a 3rd embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a vehicle air conditioner 8 according to the first embodiment. In this embodiment, for example, the refrigeration cycle apparatus 10 shown in FIG. 1 is applied to a vehicle air conditioner 8 for a hybrid vehicle or an electric vehicle. The refrigeration cycle apparatus 10 functions to cool or heat the vehicle interior air blown into the vehicle interior, which is the air conditioning target space, in the vehicle air conditioner 8.

  Therefore, the refrigeration cycle apparatus 10 includes a cooling mode refrigerant flow path for cooling the vehicle interior, that is, a cooling operation refrigerant path, and a dehumidification heating mode refrigerant flow path for dehumidification heating that dehumidifies the passenger compartment, ie, a dehumidification operation refrigerant flow path. The heating mode refrigerant flow path for heating the passenger compartment, that is, the refrigerant flow path for heating operation can be established.

  Further, in the refrigeration cycle apparatus 10, as will be described later, when the heating mode is performed for a certain period, an oil return mode for returning the lubricating oil accumulated in the indoor evaporator 20 to the compressor 11 side can be performed.

Further, in the refrigeration cycle apparatus 10 of the present embodiment, a normal chlorofluorocarbon refrigerant is employed as the refrigerant. The refrigeration cycle apparatus 10 includes a subcritical refrigeration cycle in which the pressure of the high-pressure refrigerant does not exceed the critical pressure of the refrigerant.
The refrigerant contains lubricating oil in order to lubricate a mechanism such as a bearing of the compressor 11 and a compression mechanism.

  As shown in FIG. 1, the refrigeration cycle apparatus 10 includes a compressor 11, an indoor condenser 12, a first expansion valve 14, an outdoor heat exchanger 15, a first switching valve 17, a second expansion valve 19, and an indoor evaporator 20. , An accumulator 21, a second switching valve 23, a check valve 24, a constant pressure valve 25, and an electronic control device 40.

  The compressor 11 is a device that is disposed in an engine room of a vehicle and sucks, compresses and discharges refrigerant in the refrigeration cycle apparatus 10. The compressor 11 includes an electric motor and a compression mechanism that is driven by the electric motor and compresses the refrigerant, and is an electric compressor that changes the compression power that the compressor 11 gives to the refrigerant according to the rotational speed of the electric motor. As the compression mechanism of the compressor 11, various compression mechanisms such as a scroll-type compression mechanism or a vane-type compression mechanism are employed.

  The inlet side of the indoor condenser 12 is connected to the discharge port side of the compressor 11. The indoor condenser 12 is arrange | positioned in the casing 31 of the indoor air conditioning unit 30 mentioned later. The indoor condenser 12 is a radiator that causes heat exchange between the high-pressure discharged refrigerant discharged from the compressor 11 and the air blown into the passenger compartment, and radiates heat from the discharged refrigerant.

  A first refrigerant passage 13 that guides the refrigerant flowing out of the indoor condenser 12 to the outdoor heat exchanger 15 is connected to the outlet side of the indoor condenser 12. The first refrigerant passage 13 is provided with a first expansion valve 14 configured so that the passage area of the first refrigerant passage 13 can be changed.

  Specifically, the first expansion valve 14 includes a valve body configured to be able to change the throttle opening and an electric actuator including a stepping motor that changes the throttle opening of the valve body. This is an electric variable aperture mechanism. Therefore, the first expansion valve 14 increases or decreases the throttle opening degree of the first expansion valve 14 according to the control signal output from the electronic control unit 40. The passage area of the first refrigerant passage 13 increases as the throttle opening of the first expansion valve 14 increases. The first expansion valve 14 expands the refrigerant under reduced pressure by restricting the refrigerant that passes through the first expansion valve 14 and flows into the outdoor heat exchanger 15. For this reason, the rate of decompression and expansion can be changed by changing the throttle opening of the first expansion valve 14. The first expansion valve 14 allows the refrigerant to pass through the first refrigerant passage 13 without being decompressed and expanded when the first expansion valve 14 is fully opened.

  The inlet side of the outdoor heat exchanger 15 is connected to the outlet side of the first expansion valve 14. The outdoor heat exchanger 15 exchanges heat between the refrigerant flowing through the outdoor heat exchanger 15 and the outside air blown from the blower fan 15a (that is, air outside the vehicle compartment). The outdoor heat exchanger 15 functions as an evaporator that evaporates the refrigerant and exerts an endothermic effect in a heating mode, which will be described later, and functions as a radiator that radiates the refrigerant in a cooling mode.

  A second refrigerant passage 16 and a third refrigerant passage 18 are connected to the outlet side of the outdoor heat exchanger 15. The second refrigerant passage 16 is a refrigerant passage for bypassing the refrigerant flowing out of the outdoor heat exchanger 15 to the inlet side of the accumulator 21 by bypassing the check valve 24, the second expansion valve 19, and the indoor evaporator 20. . The third refrigerant passage 18 is a refrigerant passage for guiding the refrigerant flowing out of the outdoor heat exchanger 15 to the inlet side of the indoor evaporator 20 through the check valve 24 and the second expansion valve 19.

  A first switching valve 17 is disposed in the second refrigerant passage 16. The first switching valve 17 is an electromagnetic valve that opens and closes the second refrigerant passage 16, and its operation is controlled by a control signal output from the electronic control device 40.

  In the third refrigerant passage 18, a second expansion valve 19 configured to change the passage area of the third refrigerant passage 18 is disposed. The second expansion valve 19 is an electric variable throttle mechanism similar to the first expansion valve 14 described above, and the throttle opening degree of the second expansion valve 19 is increased or decreased by a control signal output from the electronic control unit 40. To do. Specifically, the second expansion valve 19 expands the refrigerant under reduced pressure by restricting the refrigerant that passes through the second expansion valve 19 and flows into the indoor evaporator 20 in accordance with the throttle opening. In addition, the second expansion valve 19 allows the refrigerant to pass through the third refrigerant passage 18 without being decompressed and expanded when the second expansion valve 19 is fully opened, while the refrigerant flows ( That is, the third refrigerant passage 18) is blocked.

  The inlet side of the indoor evaporator 20 is connected to the outlet side of the second expansion valve 19. The indoor evaporator 20 is arranged in the casing 31 of the indoor air conditioning unit 30 on the upstream side of the air flow in the vehicle interior of the indoor condenser 12. In the indoor evaporator 20, for example, the refrigerant is circulated in the cooling mode and the dehumidifying heating mode. The indoor evaporator 20 is an evaporator that cools the air in the vehicle interior by evaporating the refrigerant flowing through the interior of the vehicle by exchanging heat with the air blown into the vehicle interior before passing through the indoor condenser 12 to exhibit heat absorption. is there.

  The outlet side of the indoor evaporator 20 is connected to the inlet side of the accumulator 21 via a constant pressure valve 25. The constant pressure valve 25 is a mechanical pressure reducing device that depressurizes the refrigerant passing through the constant pressure valve 25 by mechanical operation inside the constant pressure valve 25. Specifically, the constant pressure valve 25 maintains the pressure of the refrigerant on the inlet side of the constant pressure valve 25, that is, the outlet side of the indoor evaporator 20, at a predetermined value, in other words, maintains the pressure of the refrigerant at a constant value. The refrigerant passing through 25 is depressurized. Since the constant pressure valve 25 is the same as the low pressure valve described in Patent Document 1, detailed description thereof will be omitted.

  The accumulator 21 is a gas-liquid separator that separates the gas-liquid refrigerant flowing into the accumulator 21 and stores excess refrigerant in the cycle. The suction port side of the compressor 11 is connected to the gas phase refrigerant outlet of the accumulator 21. Therefore, the accumulator 21 functions to prevent liquid phase refrigerant from being sucked into the compressor 11 and prevent liquid compression in the compressor 11.

  Further, the refrigeration cycle apparatus 10 is provided with a bypass passage 22 for guiding the refrigerant before reaching the inlet side of the first expansion valve 14 in the first refrigerant passage 13 to the inlet side of the second expansion valve 19. In other words, the bypass passage 22 is a refrigerant passage that guides the refrigerant flowing out of the indoor condenser 12 to the inlet side of the second expansion valve 19 by bypassing the first expansion valve 14 and the outdoor heat exchanger 15. A second switching valve 23 is disposed in the bypass passage 22. The second switching valve 23 is an electromagnetic valve that opens and closes the bypass passage 22, and its operation is controlled by a control signal output from the electronic control device 40.

  Furthermore, in the present embodiment, a check valve 24 is disposed between the outlet side of the outdoor heat exchanger 15 in the third refrigerant passage 18 and the junction of the bypass passage 22 and the third refrigerant passage 18. The check valve 24 allows the refrigerant to flow from the outlet side of the outdoor heat exchanger 15 to the inlet side of the second expansion valve 19, while allowing the outdoor heat exchanger 15 to flow from the inlet side of the second expansion valve 19. Prohibit refrigerant flow to the outlet. With such a configuration, the check valve 24 prevents the refrigerant that has merged from the bypass passage 22 into the third refrigerant passage 18 from flowing to the outdoor heat exchanger 15 side.

  Next, the indoor air conditioning unit 30 will be described. The indoor air conditioning unit 30 is disposed inside the foremost instrument panel in the vehicle interior. The indoor air conditioning unit 30 includes a blower 32, the above-described indoor condenser 12, the indoor evaporator 20, and the like in a casing 31 that forms an outer shell thereof.

  The casing 31 forms an air passage for the air blown into the passenger compartment, and is formed of a resin (for example, polypropylene) having a certain degree of elasticity and excellent in strength. An inside / outside air switching device 33 that switches between outside air and inside air that is air in the passenger compartment is arranged on the most upstream side of the blown air flow in the casing 31.

  The inside / outside air switching device 33 is formed with an inside air introduction port for introducing inside air into the casing 31 and an outside air introduction port for introducing outside air. Furthermore, inside / outside air switching device 33 is provided with an inside / outside air switching door that continuously adjusts the opening area of the inside air introduction port and the outside air introduction port to change the air volume ratio between the inside air volume and the outside air volume. Has been.

  A blower 32 that blows air introduced through the inside / outside air switching device 33 toward the vehicle interior is disposed on the downstream side of the air flow of the inside / outside air switching device 33. The blower 32 is an electric sirocco fan, for example, and the amount of blown air from the blower 32 is controlled by a control signal output from the electronic control unit 40.

  On the downstream side of the air flow of the blower 32, the indoor evaporator 20 and the indoor condenser 12 are arranged in this order along the flow of the air blown into the vehicle interior. In other words, the indoor evaporator 20 is arranged on the upstream side of the air flow in the vehicle interior with respect to the indoor condenser 12.

  Here, in the casing 31, a cold air bypass passage 35 is formed in which air that has passed through the indoor evaporator 20 is caused to bypass the indoor condenser 12. An air mix door 36 is disposed downstream of the indoor evaporator 20 and upstream of the indoor condenser 12. The air mix door 36 opens and closes one of the air passage of the indoor condenser 12 and the cold air bypass passage 35.

  Further, on the downstream side of the air flow of the indoor condenser 12 and the downstream side of the air flow of the cold air bypass passage 35, a mixing space for mixing the air that has passed through the indoor condenser 12 and the air that has passed through the cold air bypass passage 35 is provided. ing. Further, an air outlet for blowing air into the passenger compartment is provided on the most downstream side of the blast air flow of the casing 31, and the conditioned air mixed in the mixing space is blown out from the outlet into the passenger compartment. The air mix door 36 is driven by a servo motor (not shown) that operates according to a control signal output from the electronic control device 40.

  As shown in FIG. 1, the refrigeration cycle apparatus 10 includes a first temperature sensor 42, a first pressure sensor 44, a second temperature sensor 46, a third temperature sensor 48, a fourth temperature sensor 50, and an outside temperature sensor. 52.

  The first temperature sensor 42 is provided between the indoor condenser 12 and the first expansion valve 14 in the first refrigerant passage 13, and detects the temperature of the refrigerant that has flowed out of the indoor condenser 12. The first pressure sensor 44 is disposed at the same location as the first temperature sensor 42 and detects the pressure of the refrigerant flowing out of the indoor condenser 12.

  The second temperature sensor 46 is provided at the refrigerant outlet of the outdoor heat exchanger 15 and detects the temperature of the refrigerant flowing out of the outdoor heat exchanger 15.

  The third temperature sensor 48 is provided in the casing 31 of the indoor air conditioning unit 30 immediately after the downstream side of the air flow with respect to the indoor evaporator 20, and the temperature Te of the vehicle interior blown air blown out from the indoor evaporator 20, that is, the evaporator blowout. The temperature Te is detected.

  The fourth temperature sensor 50 is provided in the refrigerant flow path from the indoor evaporator 20 to the constant pressure valve 25 and detects the temperature of the refrigerant flowing out of the indoor evaporator 20.

  The outside air temperature sensor 52 is provided outside the passenger compartment and detects the outside air temperature Tam.

  The electronic control unit 40 is composed of a well-known microcomputer comprising a CPU, ROM, RAM, etc. and its peripheral circuits, and executes various control processes according to a computer program stored in advance in the ROM.

  Further, as shown in FIG. 1, detection signals representing detection values are sequentially input to the electronic control device 40 from, for example, the sensors 42, 44, 46, 48, 50, 52 described above. In addition, the electronic control unit 40 includes an inside air sensor that detects a vehicle interior temperature Tr, a solar radiation sensor that detects a solar radiation amount Ts in the vehicle interior, a discharge temperature sensor that detects the temperature Td of the refrigerant discharged from the compressor 11, and Detection signals representing detection values are sequentially input from various air conditioning control sensors, such as a blowout temperature sensor that detects a blowout temperature TAV of air blown from the indoor air conditioning unit 30 into the vehicle interior.

  Furthermore, an operation panel (not shown) arranged on the instrument panel is connected to the electronic control unit 40, and operation signals from various operation switches provided on the operation panel are input. As various operation switches provided on the operation panel, specifically, an air conditioner switch for setting whether to cool the air blown in the vehicle interior by the indoor air conditioning unit 30, or a temperature setting for setting a set temperature in the vehicle interior A switch or the like is provided.

Next, the operation of this embodiment will be described. First, the electronic control unit 40 determines a target blowing temperature TAO, which is a target value for the blowing temperature TAV of the air blown into the vehicle interior, based on the detection signals from the above-described sensors and the operation signal of the operation panel. For example, the target blowing temperature TAO is the vehicle interior set temperature Tset set by the temperature setting switch in the operation panel and the vehicle detected by the inside air sensor, as in the first embodiment disclosed in Patent Document 1 described above. Based on the indoor temperature Tr, the outdoor air temperature Tam detected by the outdoor air temperature sensor 52, and the solar radiation amount Ts detected by the solar radiation sensor, it is calculated from a predetermined calculation formula. And the electronic control apparatus 40 should be implemented among cooling mode, heating mode, 1st dehumidification heating mode, and 2nd dehumidification heating mode based on the detection signal from each sensor, and the operation signal of an operation panel. One mode is determined, and the determined mode is executed based on the target blowing temperature TAO. Since the cooling mode, the heating mode, the first dehumidifying heating mode, and the second dehumidifying heating mode are the same as those disclosed in Patent Document 1 described above, the outline of each mode will be described below.
(Cooling mode)
In the cooling mode, the electronic control unit 40 blocks the second refrigerant passage 16 by the first switching valve 17 shown in FIG. 1 and blocks the bypass passage 22 by the second switching valve 23. Further, the first expansion valve 14 is fully opened. As a result, as indicated by the white arrow in FIG. 1, the electronic control unit 40 allows the refrigerant discharged from the compressor 11 to flow into the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, and the check valve. 24, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 flow in this order to establish a cooling circulation path that returns to the compressor 11.

  In addition, the electronic control unit 40 closes the air passage of the indoor condenser 12 by the air mix door 36, whereby the entire flow rate of the blown air after passing through the indoor evaporator 20 flows to the cold air bypass passage 35. .

  In the cooling mode, the electronic control unit 40 refers to the control map stored in advance in the electronic control unit 40 based on the target blowing temperature TAO, and uses the target value of the air temperature blown from the indoor evaporator 20. A target evaporator outlet temperature TEO is determined. Then, based on the deviation between the target evaporator outlet temperature TEO and the evaporator outlet temperature Te detected by the third temperature sensor 48, the compressor 11 so that the outlet temperature TAV into the passenger compartment approaches the target outlet temperature TAO. To control the rotation speed.

  Further, the electronic control unit 40 approaches the target supercooling degree set in advance so that the degree of supercooling of the refrigerant flowing into the second expansion valve 19 approaches the maximum coefficient of performance of the cycle (hereinafter referred to as COP). Thus, the throttle opening degree of the second expansion valve 19 is controlled. The degree of supercooling of the refrigerant flowing into the second expansion valve 19 is, for example, the refrigerant temperature at the outlet of the outdoor heat exchanger 15 detected by the second temperature sensor 46 and the outdoor heat detected by the first pressure sensor 44. It is calculated from the refrigerant pressure at the outlet of the exchanger 15. At this time, since the first expansion valve 14 is fully opened, the pressure of the refrigerant at the outlet of the outdoor heat exchanger 15 can be detected by the first pressure sensor 44 provided at the outlet of the indoor condenser 12.

  As described above, in the cooling mode, since the air passage of the indoor condenser 12 is closed by the air mix door 36, the air blown into the vehicle interior through the cold air bypass passage 35 is blown out from the vehicle interior air cooled by the indoor evaporator 20. be able to. Thereby, cooling of a vehicle interior is realizable.

(First dehumidifying heating mode)
In the first dehumidifying and heating mode, the electronic control unit 40 blocks the second refrigerant passage 16 by the first switching valve 17 shown in FIG. 1 and blocks the bypass passage 22 by the second switching valve 23. Moreover, the 1st expansion valve 14 and the 2nd expansion valve 19 are made into a throttle state or a full open state, respectively. As a result, the electronic control unit 40 causes the refrigerant discharged from the compressor 11 to be discharged from the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the check, as indicated by the white horizontal arrows in FIG. A first circulation path that flows in the order of the valve 24, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 and returning to the compressor 11 is established. In the first circulation path, the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in series in the refrigerant flow. The first circulation path is the same path as the cooling circulation path described above.

  Moreover, in the 1st dehumidification heating mode, the electronic control apparatus 40 controls the rotational speed of the compressor 11 similarly to the air_conditioning | cooling mode. Further, the electronic control unit 40 closes the cold air bypass passage 35 with the air mix door 36, so that the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the air passage of the indoor condenser 12. To do.

  Further, the electronic control unit 40 changes the throttle opening of the first expansion valve 14 and the throttle opening of the second expansion valve 19 according to the target blowing temperature TAO. Specifically, the electronic control unit 40 decreases the passage area of the first refrigerant passage 13 by the first expansion valve 14 and increases the third refrigerant by the second expansion valve 19 as the target blowing temperature TAO increases. The passage area of the passage 18 is increased. Thereby, the outdoor heat exchanger 15 in the first dehumidifying and heating mode may function as an evaporator or as a condenser.

(Second dehumidifying heating mode)
In the second dehumidifying and heating mode, the electronic control unit 40 opens the second refrigerant passage 16 with the first switching valve 17 shown in FIG. 1 open, and opens the bypass passage 22 with the second switching valve 23 open. Further, the first expansion valve 14 and the second expansion valve 19 are brought into the throttle state. As a result, the electronic control unit 40 establishes the second circulation path indicated by the white oblique arrow in FIG.

  The second circulation path is that the refrigerant discharged from the compressor 11 flows to the indoor condenser 12, and the first expansion valve 14, the outdoor heat exchanger 15, the first switching valve 17, and the accumulator 21 from the indoor condenser 12. And the second switching valve 23, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 in this order from the indoor condenser 12, and the refrigerant combined in the accumulator 21 flows from the accumulator 21 to the compressor. This is the route back to 11. That is, in the second circulation path, the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel in the refrigerant flow.

  When the refrigerant circulates in the second circulation path, the refrigerant does not flow back from the bypass passage 22 to the outlet side of the outdoor heat exchanger 15 due to the action of the check valve 24. Further, due to the action of the constant pressure valve 25, the refrigerant pressure in the indoor evaporator 20 is maintained higher than the refrigerant pressure in the outdoor heat exchanger 15.

  In the second dehumidifying and heating mode, the electronic control unit 40 controls the rotational speed of the compressor 11 so that the blowout temperature TAV into the passenger compartment approaches the target blowout temperature TAO, and the air mix door 36 causes the cold air bypass passage. 35 is closed.

  Further, the electronic control unit 40 is configured so that the throttle opening degree of the first expansion valve 14 and the throttle opening degree of the second expansion valve 19 are respectively predetermined opening degrees for the second dehumidifying and heating mode. Controls the electric actuator that adjusts the aperture.

  As described above, in the second dehumidifying and heating mode, unlike the first dehumidifying and heating mode, the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel to the refrigerant flow. The refrigerant flow rate to the evaporator 20 can be reduced. Accordingly, the heat absorption amount of the refrigerant in the indoor evaporator 20 can be reduced, and the vehicle interior air dehumidified by the indoor evaporator 20 is heated in the indoor condenser 12 at a higher temperature than in the first dehumidifying and heating mode. Can be adjusted.

(Heating mode)
In the heating mode, the electronic control unit 40 opens the second refrigerant passage 16 by opening the first switching valve 17 shown in FIG. 1, while blocking the bypass passage 22 by the second switching valve 23. Further, the second expansion valve 19 is fully closed, thereby preventing the refrigerant from flowing into the indoor evaporator 20. Then, the first expansion valve 14 is in the throttle state. Thereby, as shown by the black arrow in FIG. 1, the electronic control unit 40 causes the refrigerant discharged from the compressor 11 to flow into the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, and the first switching. A heating circulation path that flows in the order of the valve 17 and the accumulator 21 and returns to the compressor 11 is established. In this heating circulation path, the outdoor heat exchanger 15 functions as an evaporator.

  Further, in the heating mode, the electronic control unit 40 controls the rotation speed of the compressor 11 so that the blowing temperature TAV into the vehicle interior approaches the target blowing temperature TAO, as in the second dehumidifying heating mode, and the air mix. The cold air bypass passage 35 is closed by the door 36.

  In addition, the electronic control unit 40 controls the first expansion valve 14 so that the degree of supercooling of the refrigerant flowing into the first expansion valve 14 approaches a predetermined target degree of supercooling so that the COP approaches the maximum value. Control the throttle opening. The degree of supercooling of the refrigerant flowing into the first expansion valve 14 is, for example, the refrigerant temperature at the outlet of the indoor condenser 12 detected by the first temperature sensor 42 and the indoor condenser detected by the first pressure sensor 44. It is calculated from the refrigerant pressure at 12 outlets.

  As described above, in the heating mode, the heat of the high-pressure refrigerant discharged from the compressor 11 by the indoor condenser 12 is radiated to the vehicle interior blown air, and the heated vehicle interior blown air is blown out into the vehicle interior. Can do. Thereby, heating of a vehicle interior is realizable.

  In order to start such a heating mode, immediately after the second expansion valve 19 is closed, the refrigerant pressure in the indoor evaporator 20 may be lower than the refrigerant pressure on the refrigerant inlet side of the accumulator 21. is there. In this case, the refrigerant may flow into the indoor evaporator 20 from the refrigerant inlet side of the accumulator 21 through the constant pressure valve 25. For this reason, lubricating oil may accumulate in the indoor evaporator 20. In particular, when the indoor evaporator 20 is disposed at a lower position than the accumulator 21, the refrigerant easily flows into the indoor evaporator 20 from the refrigerant inlet side of the accumulator 21.

  Therefore, in the present embodiment, the electronic control unit 40 returns the lubricating oil accumulated in the indoor evaporator 20 to the compressor 11 side when the heating mode is continuously performed for a certain period (for example, 1 hour) or longer. Perform oil return mode.

  Specifically, the electronic control unit 40 determines whether or not the heating mode is being implemented in Step 100. And if it determines with YES in step 100 noting that heating mode is being implemented, it will be determined whether the implementation period which implemented heating mode is more than a fixed period (step 110). When the implementation period in which the heating mode is implemented is equal to or longer than a certain period, YES is determined in step 110. Accordingly, the oil return mode is executed for a certain period Δt (step 120). Thereafter, a normal mode such as a heating mode or a cooling mode is performed (step 130).

  Here, the implementation period of the heating mode is an accumulated time obtained by accumulating the periods in which the heating mode is implemented. In this embodiment, the implementation period of heating mode is counted by the counter ka. Then, every time the count value (that is, the accumulated time) of the counter ka is counted for a certain period, the oil return mode is performed while resetting the count value of the counter ka. That is, every time the heating mode is performed for a certain period, the oil return mode is performed. Details of the oil return mode will be described below.

(Oil return mode)
In the oil return mode, the electronic control unit 40 opens the second refrigerant passage 16 by opening the first switching valve 17 shown in FIG. In addition, the throttle opening of the first expansion valve 14 is set to a predetermined opening to bring the first expansion valve 14 into a throttle state. As a result, the electronic control unit 40 causes the refrigerant discharged from the compressor 11 to flow through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, and the first switching, as indicated by the black arrows in FIG. 3. A first oil return path that flows in the order of the valve 17 and the accumulator 21 and returns to the compressor 11 is established. In the first oil return path, the outdoor heat exchanger 15 functions as an evaporator.

  Further, in the oil return mode, the electronic control unit 40 controls the rotation speed of the compressor 11 so that the blowout temperature TAV into the vehicle interior approaches the target blowout temperature TAO, as in the heating mode. In addition, the electronic control unit 40 controls the first expansion valve 14 so that the degree of supercooling of the refrigerant flowing into the first expansion valve 14 approaches a predetermined target degree of supercooling so that the COP approaches the maximum value. Control the throttle opening.

  In such an oil return mode, the heat of the high-pressure refrigerant discharged from the compressor 11 by the indoor condenser 12 can be dissipated to the vehicle interior blown air, and the heated vehicle interior blown air can be blown out into the vehicle interior. it can. Thereby, heating of a vehicle interior is realizable.

  Further, in the oil return mode, the electronic control unit 40 controls the rotational speed of the compressor 11 so that the blowout temperature TAV into the passenger compartment approaches the target blowout temperature TAO, as in the heating mode. The cold air bypass passage 35 is closed by 36.

  Furthermore, if the electronic control unit 40 determines YES in step 110 of FIG. 2, it controls the throttle opening degree of the second switching valve 23 and the second expansion valve 19 as follows. Hereinafter, the timing determined as YES in step 110 is a timing ta.

  That is, the electronic control unit 40 opens the bypass passage 22 by the second switching valve 23 for a certain period (denoted as oil return operation time in FIG. 4) Δt from the timing ta. Thereafter, when the predetermined time Δt elapses from the timing ta, the second switching valve 23 closes the bypass passage 22.

  Further, the electronic control unit 40 gradually increases the throttle opening degree of the second expansion valve 19 to the predetermined opening degree Ka at the timing ta, and thereafter, when the throttle opening degree reaches the predetermined opening degree Ka, the throttle opening degree is increased. The predetermined opening degree Ka is maintained. Thereafter, when the predetermined period has elapsed and the timing tb is reached, the throttle opening of the second expansion valve 19 is gradually reduced from the predetermined opening Ka.

  Due to the control of the second switching valve 23 and the second expansion valve 19, a part of the refrigerant flowing out from the refrigerant outlet of the indoor condenser 12 is partially bypassed 22, the second switching valve 23, and the second expansion valve 19. Then, the second oil return path for returning to the compressor 11 through the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 is established. Along with this, the lubricating oil accumulated in the indoor evaporator 20 with the execution of the heating mode can be returned to the compressor side.

  In FIG. 4, it is shown that the circulation rate of the lubricating oil is increased by the control of the second switching valve 23 and the second expansion valve 19. The circulation rate of the lubricating oil is a value indicating the ratio (%) of the total amount of the lubricating oil used in the refrigeration cycle apparatus 10 to the amount of the lubricating oil that is actually circulated.

  Here, when the throttle opening degree of the second expansion valve 19 is increased, the flow rate of the refrigerant passing through the indoor evaporator 20 is increased. For this reason, there is a possibility that the temperature of the air-conditioning feeling is lowered due to a decrease in the temperature of the air that passes through the indoor condenser 12 and is blown into the vehicle interior.

  On the other hand, when the throttle opening of the second expansion valve 19 is reduced, the flow rate of the refrigerant passing through the indoor evaporator 20 is reduced, and the amount of lubricating oil returning from the indoor condenser 12 to the compressor 11 may be reduced.

  Therefore, in the present embodiment, the second expansion valve 19 is configured so as to ensure a flow rate of the minimum refrigerant or more that can return the lubricating oil to the compressor 11 side while suppressing a decrease in the air conditioning feeling due to the variation in the blowing temperature. A predetermined opening degree Ka as a throttle opening degree is set (see FIG. 5).

  Further, when the oil return operation time Δt is lengthened, the time for increasing the flow rate of the refrigerant passing through the indoor evaporator 20 becomes longer, the blowing temperature blown out from the indoor evaporator 20 into the vehicle interior is lowered, and the air conditioning feeling is lowered. There is a fear. On the other hand, if the oil return operation time Δt is shortened, the amount of lubricating oil returning from the indoor evaporator 20 to the compressor 11 may be reduced.

  Therefore, in the present embodiment, the oil return operation time Δt is set so as to ensure a minimum refrigerant flow rate at which the lubricating oil returns to the compressor 11 side while suppressing a decrease in the air conditioning feeling due to the variation in the blowout temperature ( (See FIG. 5).

  According to the present embodiment described above, the refrigeration cycle apparatus 10 exchanges heat between the compressor 11 that compresses and discharges the refrigerant containing the lubricating oil, and the air that is blown into the vehicle interior and the refrigerant. And an indoor condenser 12 that radiates heat from the refrigerant, and an outdoor heat exchanger 15 that exchanges heat between the refrigerant and the outside air. The refrigeration cycle apparatus 10 is configured to cause heat exchange between the blown air before passing through the indoor condenser 12 and the refrigerant to evaporate the refrigerant, and to cause the refrigerant to flow out to the suction side of the compressor 11; A first expansion valve 14 that decompresses and expands the refrigerant flowing into the outdoor heat exchanger 15 and a second expansion valve 19 that decompresses and expands the refrigerant that flows into the indoor evaporator 20 are provided.

  When the electronic control unit 40 determines that the heating mode is performed for a certain period of time and determines YES in step 110, the refrigerant discharged from the compressor 11 is in the order of the indoor condenser 12, the second expansion valve 19, and the indoor evaporator 20. An oil return mode is performed in which the oil is returned to the compressor 11 (step 120).

  Therefore, after carrying out the heating mode for a certain period, the refrigerant flows in the order from the indoor condenser 12 to the bypass passage 22, the second expansion valve 19, the indoor evaporator 20, and the compressor 11. Lubricating oil accumulated in the evaporator 20 can be returned to the compressor side.

  Furthermore, in this embodiment, the refrigerant pressure on the outlet side of the indoor evaporator 20 can be maintained at a predetermined value by arranging the constant pressure valve 25 on the outlet side of the indoor evaporator 20. Thereby, the frost in the indoor evaporator 20 can be prevented beforehand.

  In the present embodiment, the oil return operation time Δt and the predetermined opening degree Ka (throttle opening degree of the second expansion valve 19) are determined in consideration of the air conditioning feeling and the amount of lubricating oil returning to the compressor 11 as described above. It has been. For this reason, the oil return mode can ensure the circulation rate of the lubricating oil in the refrigeration cycle apparatus 10 without impairing the air conditioning feeling.

(Second Embodiment)
In the first embodiment, the example in which the refrigerant that has passed through the bypass passage 22 is caused to flow to the indoor evaporator 20 through the second expansion valve 19 in the oil return mode has been described. Instead, in the oil return mode, the outdoor heat An example of flowing the refrigerant that has passed through the exchanger 15 through the second expansion valve 19 to the indoor evaporator 20 will be described with reference to FIGS. 6 and 7.

  In the oil return mode of the present embodiment, the electronic control unit 40 closes the first switching valve 17 and closes the second refrigerant passage 16 shown in FIG. 7 and closes the second switching valve 23 to close the bypass passage. 22 is cut off. As a result, the electronic control unit 40 causes the refrigerant discharged from the compressor 11 to pass through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the check, as indicated by the point hatched arrows in FIG. 7. An oil return path is established in which the valve 24, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 flow in this order and return to the compressor 11. In this oil return path, the outdoor heat exchanger 15 functions as an evaporator or a radiator, and the indoor evaporator 20 functions as an evaporator.

  Further, in the oil return mode, the electronic control unit 40 controls the rotation speed of the compressor 11 so that the blowout temperature TAV into the vehicle interior approaches the target blowout temperature TAO, as in the heating mode. In addition, the electronic control unit 40 controls the first expansion valve 14 so that the degree of supercooling of the refrigerant flowing into the first expansion valve 14 approaches a predetermined target degree of supercooling so that the COP approaches the maximum value. Control the throttle opening.

  In addition to this, the electronic control unit 40 controls the throttle opening of the second expansion valve 19 as in the first embodiment. That is, the electronic control unit 40 gradually increases the throttle opening of the second expansion valve 19 to the predetermined opening Ka, and then when the throttle opening reaches the predetermined opening Ka, the electronic control unit 40 sets the throttle opening to the predetermined opening Ka. To maintain.

  As described above, the refrigerant discharged from the compressor 11 is supplied to the indoor condenser 12, the first expansion valve 14, and the outdoor heat exchanger 15 by controlling the first switching valve 17, the second switching valve 23, and the second expansion valve 19. Then, the check valve 24, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 are flowed in this order to establish an oil return path for returning to the compressor 11. Along with this, the lubricating oil accumulated in the indoor evaporator 20 with the execution of the heating mode can be returned to the compressor side.

  In the present embodiment described above, the oil return mode is performed in which the refrigerant that has passed through the outdoor heat exchanger 15 flows into the indoor evaporator 20 through the second expansion valve 19 and is returned to the compressor 11. Therefore, the lubricating oil collected in the indoor evaporator 20 with the implementation of the heating mode can be returned to the compressor side.

  In the present embodiment, in the oil return mode, the electronic control unit 40 controls the rotation speed of the compressor 11 so that the blowing temperature TAV into the vehicle interior approaches the target blowing temperature TAO, as in the heating mode. The cold air bypass passage 35 is closed by the air mix door 36.

  Therefore, the heat of the high-pressure refrigerant discharged from the compressor 11 by the indoor condenser 12 can be dissipated to the vehicle interior blown air, and the heated vehicle interior blown air can be blown out into the vehicle interior. Thereby, heating of a vehicle interior is realizable.

  In this embodiment, the electronic control unit 40 is not the time for opening the bypass passage 22 by the second switching valve 23, but closes the second refrigerant passage 16 by the first switching valve 17 and bypasses the bypass passage by the second switching valve 23. The time for closing 22 is controlled as the oil return operation time Δt.

  Here, the oil return operation time Δt is determined in consideration of the air conditioning feeling and the amount of lubricating oil returning to the compressor 11 as in the first embodiment. For this reason, the oil return mode can ensure the circulation rate of the lubricating oil in the refrigeration cycle apparatus 10 without impairing the air conditioning feeling.

(Third embodiment)
In the first embodiment, in the oil return mode, the control is performed once by opening the bypass passage 22 by the second switching valve 23 and maintaining the throttle opening of the second expansion valve 19 at the predetermined opening Ka. Instead of this, in the present embodiment, in the oil return mode, the second switching valve 23 opens the bypass passage 22 and maintains the throttle opening of the second expansion valve 19 at the predetermined opening Ka. An example in which the above is performed a plurality of times will be described.

  In the present embodiment, the electronic control unit 40 controls to open the bypass passage 22 by the second switching valve 23 and maintain the throttle opening of the second expansion valve 19 at the predetermined opening Ka in the oil return mode of FIG. Is intermittently performed twice. For this reason, the circulation rate of the lubricating oil in the refrigeration cycle apparatus 10 can be improved as compared with the first embodiment.

(Other embodiments)
In the first, second, and third embodiments described above, in the refrigeration cycle apparatus 10, a subcritical refrigeration cycle in which the pressure of the high-pressure refrigerant does not exceed the critical pressure of the refrigerant using a chlorofluorocarbon refrigerant as the refrigerant is configured. As described above, instead of this, a supercritical refrigeration cycle in which the pressure of the high-pressure refrigerant exceeds the critical pressure of the refrigerant may be configured by the refrigeration cycle apparatus 10. In this case, carbon dioxide or the like can be used as the refrigerant.

  In the third embodiment, the example in which the control for maintaining the throttle opening degree of the second expansion valve 19 at the predetermined opening degree Ka in the oil return mode has been performed twice, but instead, in the oil return mode, The control for maintaining the throttle opening of the second expansion valve 19 at the predetermined opening Ka may be performed twice or more.

  Similarly, when carrying out the present invention, in the second embodiment, the throttle opening degree of the second expansion valve 19 is set to the predetermined opening degree Ka with the second refrigerant passage 16 closed by the first switching valve 17. You may implement the control to maintain twice or more.

  In the first, second, and third embodiments described above, the electronic control unit 40 controls the air in the indoor condenser 12 and the heater core 34 during each operation mode of the heating mode, the cooling mode, the dehumidifying heating mode, and the oil return mode. Although an example in which the air mix door 36 is operated so as to close either the passage or the cold air bypass passage 35 has been described, the operation of the air mix door 36 is not limited thereto.

  For example, the air mix door 36 may open both the air passage of the indoor condenser 12 and the heater core 34 and the cold air bypass passage 35. The temperature of the air blown into the vehicle interior may be adjusted by adjusting the air volume ratio between the air volume that passes through the air passages of the indoor condenser 12 and the heater core 34 and the air volume that passes through the cold air bypass passage 35. Good. Such temperature adjustment is effective in that it is easy to finely adjust the temperature of the air blown into the passenger compartment.

  In each of the above-described embodiments, the heater core 34 that heats air with engine cooling water (hot water) may be added to the interior of the indoor air conditioning unit 30.

  In each of the above-described embodiments, the constant pressure valve 25 keeps the refrigerant pressure at the inlet side of the constant pressure valve 25 constant by mechanical operation inside the constant pressure valve 25, but may be an electric control valve such as an electromagnetic valve. Good.

  In each of the above-described embodiments, the example in which the refrigeration cycle apparatus 10 of the present invention is applied to the vehicle air conditioner 8 has been described. However, the present invention is not limited thereto, and may be applied to, for example, a stationary air conditioner. .

  In each of the above-described embodiments, the first expansion valve 14 has a function of blocking the refrigerant flow by being fully closed, but the first expansion valve 14 does not have a function of blocking the refrigerant flow. The refrigeration cycle apparatus 10 may include an on-off valve disposed in series with the first expansion valve 14. The same applies to the second expansion valve 19. That is, a valve body (open / close valve) that opens and closes the third refrigerant passage 18 may be provided in addition to the second expansion valve 19 as a valve body that increases or decreases the throttle opening.

  In the above-described embodiment, the processing of each step shown in the flowchart of FIG. 2 is realized by a computer program, but may be configured by hardware logic.

  In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes.

DESCRIPTION OF SYMBOLS 8 Vehicle air conditioner 10 Refrigeration cycle apparatus 11 Compressor 12 Indoor condenser 14 First expansion valve 15 Outdoor heat exchanger 17 First switching valve 19 Second expansion valve (open / close valve)
20 indoor evaporator 21 accumulator 23 second switching valve 24 check valve 25 constant pressure valve 40 electronic control unit

Claims (5)

A compressor (11) for compressing and discharging a refrigerant containing lubricating oil;
A heat radiator (12) that causes heat exchange between the air blown into the air-conditioning target space and the refrigerant, and dissipates heat from the refrigerant;
An outdoor heat exchanger (15) for exchanging heat between the refrigerant and the outside air;
An evaporator (20) for causing the refrigerant to evaporate by exchanging heat between the blown air before passing through the radiator and the refrigerant, and for causing the refrigerant to flow out to the suction side of the compressor;
A first expansion valve (14) disposed between a refrigerant outlet of the radiator and a refrigerant inlet of the outdoor heat exchanger to decompress and expand the refrigerant flowing into the outdoor heat exchanger; and the outdoor heat exchanger An on-off valve (19) for opening and closing between the refrigerant outlet of the refrigerant and the refrigerant inlet of the evaporator;
The refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the evaporator are closed by the on-off valve, and the refrigerant discharged from the compressor is supplied to the radiator, the first expansion valve, and the outdoor heat exchanger. Determining means (S110) for determining whether or not the heating mode for returning to the compressor by flowing in the order of is performed for a certain period;
When the determination means determines that the heating mode has been performed for a certain period of time, a gap between the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the evaporator is opened by the on-off valve and discharged from the compressor. A control means (S120) for implementing an oil return mode in which the refrigerant flows through the radiator and the refrigerant downstream of the radiator flows in the order of the on-off valve and the evaporator and returns to the compressor. ,
A bypass passage (22) for allowing the refrigerant on the downstream side of the refrigerant flow of the radiator to bypass the outdoor heat exchanger and flow to the inlet side of the on-off valve;
A first switching valve (23) for opening and closing the bypass passage,
In the oil return mode, the control means flows the refrigerant discharged from the compressor in the order of the radiator, the first expansion valve, and the outdoor heat exchanger, and returns the refrigerant to the compressor. The bypass valve is opened by a switching valve, and the refrigerant discharged from the compressor is flowed in the order of the radiator, the bypass passage, the first switching valve, the on-off valve, and the evaporator to return to the compressor. it is in the vapor compression refrigeration cycle apparatus according to claim. A compressor (11) for compressing and discharging a refrigerant containing lubricating oil;
A heat radiator (12) that causes heat exchange between the air blown into the air-conditioning target space and the refrigerant, and dissipates heat from the refrigerant;
An outdoor heat exchanger (15) for exchanging heat between the refrigerant and the outside air;
An evaporator (20) for causing the refrigerant to evaporate by exchanging heat between the blown air before passing through the radiator and the refrigerant, and for causing the refrigerant to flow out to the suction side of the compressor;
A first expansion valve (14) disposed between a refrigerant outlet of the radiator and a refrigerant inlet of the outdoor heat exchanger to decompress and expand the refrigerant flowing into the outdoor heat exchanger; and the outdoor heat exchanger An on-off valve (19) for opening and closing between the refrigerant outlet of the refrigerant and the refrigerant inlet of the evaporator;
The refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the evaporator are closed by the on-off valve, and the refrigerant discharged from the compressor is supplied to the radiator, the first expansion valve, and the outdoor heat exchanger. Determining means (S110) for determining whether or not the heating mode for returning to the compressor by flowing in the order of is performed for a certain period;
When the determination means determines that the heating mode has been performed for a certain period of time, a gap between the refrigerant outlet of the outdoor heat exchanger and the refrigerant inlet of the evaporator is opened by the on-off valve and discharged from the compressor. A control means (S120) for implementing an oil return mode in which the refrigerant flows through the radiator and the refrigerant downstream of the radiator flows in the order of the on-off valve and the evaporator and returns to the compressor. ,
A refrigerant passage (16) for allowing the refrigerant flowing from the outdoor heat exchanger to flow to the refrigerant inlet of the compressor bypassing the on-off valve and the evaporator;
A second switching valve (17) for opening and closing the refrigerant passage,
In the oil return mode, the control means closes the refrigerant passage by the second switching valve, and converts the refrigerant discharged from the compressor into the radiator, the first expansion valve, the outdoor heat exchanger, The vapor compression refrigeration cycle apparatus is configured to flow in the order of the on-off valve and the evaporator and return to the compressor. The on-off valve is a second expansion valve configured to be capable of changing a refrigerant throttle opening for decompressing and expanding the refrigerant flowing into the evaporator.
The control means controls the second expansion valve in the oil return mode so that the refrigerant throttle opening becomes a predetermined opening determined in advance.
3. The vapor compression refrigeration cycle apparatus according to claim 1, wherein the time for which the control unit controls the second expansion valve is a predetermined time set in advance. 4. In the oil return mode, the control means intermittently repeatedly performs the operation of flowing the refrigerant on the downstream side of the refrigerant flow of the radiator in the order of the on-off valve and the evaporator and returning the refrigerant to the compressor. The vapor compression refrigeration cycle apparatus according to any one of claims 1 to 3 . The pressure adjusting valve (25) disposed between a refrigerant inlet of the compressor and a refrigerant outlet of the evaporator and holding a refrigerant pressure in the evaporator at a predetermined pressure. 5. The vapor compression refrigeration cycle apparatus according to any one of 4 above.

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