Refrigeration cycle device

Abstract

Compressor (11) that sucks in refrigerant and discharges after compression; heat radiating portion (12, 20, 22) that radiates heat to air that is blown to an air conditioning target space by causing the refrigerant discharged from the compressor to exchange heat with the air; first pressure reducing portion (13) that can reduce the pressure of the refrigerant and shut off the flow path of the refrigerant; first evaporation portion (14) that evaporates the refrigerant by causing the refrigerant reduced in pressure in the first pressure reducing portion to exchange heat with the air to absorb heat from the air; second pressure reducing portion (16) that is arranged in parallel with the first pressure reducing portion in the flow path of the refrigerant and reduces the pressure of the refrigerant; second evaporation portion (17) that evaporates the refrigerant by causing the refrigerant reduced in pressure in the second pressure reducing portion to absorb heat; and control portion (60) that, in a case where it is determined that the first pressure reducing portion shuts off the flow path and refrigeration machine oil mixed in the refrigerant is retained in the first evaporation portion, executes oil recovery control that controls the first pressure reducing portion in a manner to open the flow path.

Description

[0001] Citation of relevant applications

[0002] This application is based on Japanese Patent Application No. 2020-168603, filed on October 5, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a refrigeration cycle apparatus having multiple evaporators. Background Technology

[0004] Previously, Patent Document 1 described a refrigeration circulation device capable of regulating the air inside a vehicle and cooling the battery.

[0005] In this prior art refrigeration cycle device, the first expansion valve and air-cooled evaporator are connected in parallel with the second expansion valve and cooling water-cooled evaporator in the refrigerant flow path.

[0006] The first expansion valve reduces the pressure of the refrigerant flowing into the air-cooled evaporator. The air-cooled evaporator cools the air supplied to the vehicle interior. The second expansion valve reduces the pressure of the refrigerant flowing into the coolant-cooled evaporator. The coolant-cooled evaporator cools the air supplied to the vehicle interior.

[0007] In heating mode, the flow of refrigerant to the air-cooled evaporator is cut off by closing the first expansion valve, thereby stopping the air cooling in the air-cooled evaporator.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2019-26111 Summary of the Invention

[0011] In the aforementioned prior art, the flow of refrigerant to the air-cooled evaporator is cut off by closing the first expansion valve during heating mode. However, sometimes the flow of refrigerant to the air-cooled evaporator cannot be completely cut off. In this case, refrigeration oil mixed with the refrigerant may accumulate in the air-cooled evaporator, potentially leading to insufficient lubrication of the compressor.

[0012] In view of the above problems, the purpose of this disclosure is to effectively recover the refrigeration oil accumulated in the evaporator.

[0013] A refrigeration cycle apparatus according to one aspect of the present disclosure includes a compressor, a heat dissipation unit, a first pressure reducing unit, a first evaporation unit, a second pressure reducing unit, a second evaporation unit, and a control unit.

[0014] The compressor draws in refrigerant and discharges it after compression. The heat dissipation section allows the refrigerant discharged from the compressor to exchange heat with the air being circulated into the air-conditioned space, thereby dissipating heat to the air.

[0015] The first pressure-reducing section can reduce the pressure of the refrigerant and close the refrigerant flow path. The first evaporating section evaporates the refrigerant by absorbing heat from the air through heat exchange between the refrigerant, which has been depressurized in the first pressure-reducing section, and the air.

[0016] The second pressure-reducing section is arranged in parallel with the first pressure-reducing section in the refrigerant flow path, and reduces the pressure of the refrigerant. The second evaporating section evaporates the refrigerant by causing the refrigerant, after being reduced in pressure in the second pressure-reducing section, to absorb heat.

[0017] If the control unit determines that the flow path of the first pressure reducing section is closed and the refrigeration oil mixed with refrigerant is retained in the first evaporation section, it performs oil recovery control of the first pressure reducing section by opening the flow path.

[0018] In this way, since the refrigerant flows to the first evaporator by opening the refrigerant flow path through the first pressure reducing section, the refrigeration oil remaining in the first evaporator can be returned to the compressor. Attached Figure Description

[0019] The above-mentioned objects, other objects, features and advantages of this disclosure will become clearer with reference to the accompanying drawings and the following detailed description.

[0020] Figure 1 This is an overall structural diagram of the refrigeration cycle device according to the first embodiment.

[0021] Figure 2 This is a block diagram showing the electrical control section of the refrigeration cycle apparatus according to the first embodiment.

[0022] Figure 3 This is an overall structural diagram showing the working state of the refrigeration cycle device in the refrigeration mode of the first embodiment.

[0023] Figure 4 This is an overall structural diagram showing the working state of the refrigeration cycle device in the heating mode of the first embodiment.

[0024] Figure 5 This is an overall structural diagram showing the working state of the refrigeration cycle device in the dehumidification and heating mode of the first embodiment.

[0025] Figure 6 This is an overall structural diagram showing the operating state of the refrigeration cycle device in the battery cooling mode of the first embodiment.

[0026] Figure 7 This is a flowchart illustrating a portion of the control processing performed by the control device in the first embodiment.

[0027] Figure 8 This is a flowchart illustrating a portion of the control processing performed by the control device in the first embodiment.

[0028] Figure 9 This is a flowchart illustrating a portion of the control processing performed by the control device in the second embodiment.

[0029] Figure 10 This is an overall structural diagram of the refrigeration cycle device according to the third embodiment. Detailed Implementation

[0030] Hereinafter, various methods for implementing this disclosure will be described with reference to the accompanying drawings. In each embodiment, the same reference numerals are sometimes used to denote parts corresponding to those described in previous embodiments, and repeated descriptions are omitted. In cases where only a portion of the structure is described in each embodiment, other previously described embodiments can be applied to the remaining parts of the structure. Not only are combinations of combinable parts specifically and explicitly described in each embodiment, but even if not explicitly stated, embodiments can be partially combined as long as they do not hinder the combination.

[0031] (First Implementation)

[0032] The embodiments will now be described with reference to the accompanying drawings. Figure 1 The vehicle air conditioning unit 1 shown is an air conditioning unit that adjusts the interior space of the vehicle (in other words, the space to be conditioned) to a suitable temperature. The vehicle air conditioning unit 1 has a refrigeration circulation device 10. In this embodiment, the refrigeration circulation device 10 is installed in a hybrid electric vehicle that obtains driving force for vehicle travel from an engine (in other words, an internal combustion engine) and a driving electric motor.

[0033] The hybrid vehicle of this embodiment is configured as a plug-in hybrid vehicle that can charge the battery (in other words, the on-board battery) installed in the vehicle with electricity supplied from an external power source (in other words, commercial power source) when the vehicle is parked. For example, a lithium-ion battery can be used as the battery.

[0034] The driving force output from the engine is used not only for vehicle propulsion but also for powering the generator. Furthermore, the electricity generated by the generator and the electricity supplied from an external power source can be stored in the battery. The electricity stored in the battery is supplied not only to the motor for driving but also to various vehicle-mounted devices, such as the electric component that constitutes the refrigeration cycle unit 10.

[0035] The refrigeration cycle unit 10 is a vapor compression refrigeration machine including a compressor 11, a condenser 12, a storage tank 18, a first expansion valve 13, an air evaporator 14, a constant pressure valve 15, a second expansion valve 16, and a cooling evaporator 17. In the refrigeration cycle unit 10 of this embodiment, a Freon-based refrigerant is used as the refrigerant, forming a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant. Refrigeration oil (specifically PAG oil) used for lubricating the compressor 11 is mixed into the refrigerant. A portion of the refrigeration oil circulates in the loop along with the refrigerant.

[0036] Compressor 11 is an electric compressor driven by electricity supplied from a battery, which draws in refrigerant from the refrigeration cycle unit 10 and discharges it after compression. Compressor 11 may also be a variable capacity compressor driven by a belt.

[0037] The condenser 12 is a high-pressure refrigerant heat exchanger that condenses the high-pressure refrigerant by exchanging heat between the high-pressure refrigerant discharged from the compressor 11 and the cooling water of the high-temperature cooling water circuit 20.

[0038] The cooling water in the high-temperature cooling water circuit 20 is a fluid that serves as a heat transfer medium. The cooling water in the high-temperature cooling water circuit 20 is a high-temperature heat transfer medium. In this embodiment, a liquid or antifreeze liquid containing at least ethylene glycol, dimethylpolysiloxane, or nanofluids is used as the cooling water in the high-temperature cooling water circuit 20. The high-temperature cooling water circuit 20 is a high-temperature heat transfer medium circuit for circulating high-temperature heat transfer medium.

[0039] The storage tank 18 is a gas-liquid separation section that separates the refrigerant from the condenser 12, allows the liquid refrigerant to flow downstream, and stores the remaining refrigerant in the circulation loop. The flow of the liquid refrigerant from the storage tank 18 branches at the branching section 10a.

[0040] The first expansion valve 13 is a first pressure-reducing section that causes the liquid refrigerant flowing from the storage tank 18 to expand under reduced pressure. The first expansion valve 13 is an electrically operated variable throttling mechanism, having a valve core and an electric actuator. The valve core is configured to change the opening degree of the refrigerant flow path (in other words, the throttling opening degree). The electric actuator has a stepper motor that changes the throttling opening degree of the valve core.

[0041] The first expansion valve 13 is composed of a variable throttling mechanism with a fully closed function that completely shuts off the refrigerant flow path. That is, the first expansion valve 13 can cut off the flow of refrigerant by completely closing the refrigerant flow path. The operation of the first expansion valve 13 is controlled by... Figure 2 The control signal output by the control device 60 shown is used for control.

[0042] The air evaporator 14 is a refrigerant-air heat exchanger that cools the air supplied to the vehicle interior by exchanging heat between the refrigerant flowing out of the first expansion valve 13 and the air supplied to the vehicle interior. The air evaporator 14 is a first evaporation section that evaporates the refrigerant by absorbing heat from the air supplied to the vehicle interior.

[0043] The constant pressure valve 15 is a pressure regulating unit (in other words, a pressure regulating and pressure reducing unit) that maintains the refrigerant pressure at the outlet side of the air evaporator 14 at a predetermined value. The constant pressure valve 15 is composed of a mechanical variable throttling mechanism. Specifically, when the refrigerant pressure at the outlet side of the air evaporator 14 is lower than the predetermined value, the constant pressure valve 15 reduces the refrigerant flow path area (i.e., throttling opening) and increases the refrigerant flow path area (i.e., throttling opening) when the refrigerant pressure at the outlet side of the air evaporator 14 exceeds the predetermined value.

[0044] In cases where the flow rate of the circulating refrigerant in the circulation loop varies little, a fixed throttling valve consisting of a throttling orifice, capillary tube, etc., can be used instead of the constant pressure valve 15.

[0045] The second expansion valve 16 and the cooling evaporator 17 are configured in parallel with the first expansion valve 13, the air evaporator 14 and the constant pressure valve 15 in the refrigerant flow path.

[0046] The second expansion valve 16 is a second pressure-reducing section that causes the liquid refrigerant flowing from the condenser 12 to expand under reduced pressure. The second expansion valve 16 is an electrically operated variable throttling mechanism, having a valve core and an electric actuator. The valve core is configured to change the opening degree of the refrigerant flow path (in other words, the throttling opening degree). The electric actuator has a stepper motor that changes the throttling opening degree of the valve core.

[0047] The second expansion valve 16 is composed of a variable throttling mechanism with a fully closed function that completely shuts off the refrigerant flow path. That is, the second expansion valve 16 can cut off the flow of refrigerant by completely closing the refrigerant flow path. The operation of the second expansion valve 16 is controlled by a control signal output from the control device 60.

[0048] The cooling evaporator 17 is a low-pressure refrigerant heat exchanger that cools the cooling water by exchanging heat between the low-pressure refrigerant flowing from the second expansion valve 16 and the cooling water in the low-temperature cooling water circuit 30. The cooling evaporator 17 is a second evaporation section that allows the refrigerant to absorb heat from the cooling water and evaporate. The vaporized refrigerant after evaporation in the cooling evaporator 17 merges with the refrigerant flowing from the constant pressure valve 15 in the confluence section 10b, and is then drawn into the compressor 11 and compressed.

[0049] The cooling water in the low-temperature cooling water circuit 30 is a fluid that serves as a heat transfer medium. The cooling water in the low-temperature cooling water circuit 30 is a low-temperature heat transfer medium. In this embodiment, a liquid or antifreeze liquid containing at least ethylene glycol, dimethylpolysiloxane, or nanofluids is used as the cooling water in the low-temperature cooling water circuit 30. The low-temperature cooling water circuit 30 is a low-temperature heat transfer medium circuit for circulating a low-temperature heat transfer medium.

[0050] The high-temperature cooling water circuit 20 is equipped with a condenser 12, a high-temperature side pump 21, a heater core 22, a high-temperature side radiator 23, an on / off valve 24, and an electric heater 25.

[0051] The high-temperature side pump 21 is a heat transfer pump that draws in cooling water and discharges it. The high-temperature side pump 21 is an electrically powered pump. The high-temperature side pump 21 is a high-temperature flow regulating unit that adjusts the flow rate of the cooling water circulating in the high-temperature cooling water circuit 20. The low-temperature side pump 31 is a low-temperature flow regulating unit that adjusts the flow rate of the cooling water circulating in the low-temperature cooling water circuit 30.

[0052] The heater core 22 is an air heating heat exchanger that heats the air supplied to the vehicle interior by exchanging heat between the cooling water in the high-temperature cooling water circuit 20 and the air supplied to the vehicle interior. In the heater core 22, the cooling water dissipates heat from the air supplied to the vehicle interior. The condenser 12, the high-temperature cooling water circuit 20, and the heater core 22 form a heat dissipation section that heats the air by exchanging heat between the refrigerant discharged from the compressor 11 and the air supplied to the vehicle interior.

[0053] The high-temperature side radiator 23 is a high-temperature heat medium external air heat exchanger that allows the cooling water in the high-temperature cooling water circuit 20 to exchange heat with the external air. The high-temperature side radiator 23 and the on / off valve 24 are arranged in parallel with the heater core 22 in the flow path of the high-temperature side cooling water.

[0054] The on / off valve 24 is a solenoid valve that opens and closes the cooling water flow path on the high-temperature side of the radiator 23. The operation of the on / off valve 24 is controlled by the control device 60. The on / off valve 24 is a high-temperature switching unit that switches the flow of cooling water in the high-temperature cooling water circuit 20.

[0055] The on / off valve 24 can also be a thermostat. A thermostat is a cooling water temperature-responsive valve that includes a mechanical mechanism. This mechanical mechanism opens and closes the cooling water flow path by causing the valve core to shift due to the volume of hot wax (Japanese: サーモワックス) that changes with temperature.

[0056] The electric heater 25 is an auxiliary heating unit that provides auxiliary heating to the cooling water in the high-temperature cooling water circuit 20. The electric heater 25 is also an auxiliary heat source for heating air in the heater core 22. As the electric heater 25, a PTC heater or similar device that generates heat by supplying electricity can be used. The electric heater 25 is a Joule heating unit that produces Joule heat. The heat output of the electric heater 25 is controlled by a control voltage output from the control device 60.

[0057] The low-temperature cooling water circuit 30 is equipped with a cooling evaporator 17, a low-temperature side pump 31, a low-temperature side radiator 32, a battery 33, and a three-way valve 38.

[0058] The cryogenic side pump 31 is a heat medium pump that draws in cooling water and discharges it. The cryogenic side pump 31 is an electric pump. The cryogenic side radiator 32 is a cryogenic heat medium external air heat exchanger that allows the cooling water in the cryogenic cooling water circuit 30 to exchange heat with the outside air.

[0059] Battery 33 is an on-board device installed in the vehicle and is a heat-generating device that generates heat during operation. Battery 33 dissipates the waste heat generated during operation to the cooling water in the low-temperature cooling water circuit 30. In other words, battery 33 supplies heat to the cooling water in the low-temperature cooling water circuit 30.

[0060] The low-temperature side radiator 32 and battery 33 are configured in parallel with each other in the flow path of the low-temperature side cooling water. A three-way valve 38 switches the flow of the low-temperature side cooling water relative to the low-temperature side radiator 32 and battery 33. The operation of the three-way valve 38 is controlled by the control device 60.

[0061] The air evaporator 14 and heater core 22 are housed in Figure 1 The interior air conditioning unit 50 shown is housed in its outer casing 51 (hereinafter referred to as the air conditioning casing). The interior air conditioning unit 50 is disposed inside an instrument panel (not shown) at the front of the vehicle interior. The air conditioning casing 51 is an air passage forming member that forms an air passage.

[0062] The heater core 22 is disposed downstream of the air evaporator 14 in the air passage within the air conditioning housing 51. An indoor / outdoor air switching box 52 and an indoor fan 53 are disposed within the air conditioning housing 51. The indoor / outdoor air switching box 52 has an indoor / outdoor air switching door 52a. The indoor / outdoor air switching door 52a is an indoor / outdoor air switching unit that switches between internal and external air entering the air passage within the air conditioning housing 51. The indoor / outdoor air switching door 52a is an indoor / outdoor air conditioning unit that adjusts the ratio of internal air to external air entering the air passage within the air conditioning housing 51.

[0063] The indoor air supply fan 53 draws in and supplies both internal and external air into the air passageway inside the air conditioning unit 51 via the internal / external air switching box 52. The internal / external air switching door 52a and the indoor air supply fan 53 are controlled by the control device 60.

[0064] An air mixing valve 54 is disposed between the air evaporator 14 and the heater core 22 in the air passage inside the air conditioner housing 51. The air mixing valve 54 adjusts the airflow ratio between the cold air flowing into the heater core 22 from the cold air after passing through the air evaporator 14 and the cold air flowing through the cold air bypass passage 55.

[0065] The cold air bypass passage 55 is an air passage through which the cold air after passing through the air evaporator 14 flows around the heater core 22.

[0066] The air mixing valve 54 is a rotary door having a rotating shaft rotatably supported on the air conditioning housing 51 and a door base plate portion connected to the rotating shaft. By adjusting the opening position of the air mixing valve 54, the temperature of the air conditioning air blown from the air conditioning housing 51 into the vehicle interior can be adjusted to the desired temperature.

[0067] The rotation shaft of the air mixing valve 54 is driven by a servo motor. The operation of the servo motor is controlled by the control device 60.

[0068] The air mixing valve 54 can also be a sliding door that slides in a direction approximately orthogonal to the airflow. The sliding door can also be a plate-shaped door formed of a rigid body, or a membrane door formed of a flexible thin-film material.

[0069] The air conditioning air, after being regulated by the air mixing valve 54, is blown into the vehicle interior from the outlet 56 formed in the air conditioning housing 51.

[0070] Figure 2 The control device 60 shown is composed of a known microcomputer including a CPU, ROM, and RAM, and its peripheral circuitry. The control device 60 performs various calculations and processes based on a control program stored in the ROM. Various controlled devices are connected to the output side of the control device 60. The control device 60 is a control unit that controls the actions of these various controlled devices.

[0071] The controlled devices controlled by the control device 60 include compressor 11, first expansion valve 13, second expansion valve 16, high-temperature side pump 21, on / off valve 24, electric heater 25, low-temperature side pump 31, three-way valve 38, indoor / outdoor air switching door 52a, and indoor fan 53.

[0072] The software and hardware in control device 60 that control the motor of compressor 11 constitute a refrigerant discharge capacity control unit. The software and hardware in control device 60 that control the first expansion valve 13 constitute a first throttling control unit. The software and hardware in control device 60 that control the second expansion valve 16 constitute a second throttling control unit.

[0073] The software and hardware in control device 60 that control the high-temperature side pump 21 constitute a high-temperature hot medium flow control unit. The software and hardware in control device 60 that control the on / off valve 24 constitute an on / off valve control unit.

[0074] The software and hardware in control device 60 that control the electric heater 25 constitute an auxiliary heating control unit. The software and hardware in control device 60 that control the cryogenic side pump 31 constitute a cryogenic heat medium flow control unit. The software and hardware in control device 60 that control the three-way valve 38 constitute a three-way valve control unit.

[0075] Various control sensor groups are connected to the input side of the control device 60, including an internal air temperature sensor 61, an external air temperature sensor 62, a solar radiation sensor 63, an evaporator temperature sensor 64, a heater core temperature sensor 65, a refrigerant pressure sensor 66, a high-temperature cooling water temperature sensor 67, a low-temperature cooling water temperature sensor 68, and a window surface humidity sensor 69.

[0076] The interior air temperature sensor 61 detects the interior temperature Tr. The exterior air temperature sensor 62 detects the exterior air temperature Tam. The solar radiation sensor 63 detects the solar radiation As inside the vehicle.

[0077] The evaporator temperature sensor 64 is a temperature detection unit that detects the temperature TE of the cooling evaporator 17. Examples of the evaporator temperature sensor 64 include fin thermistors that detect the temperature of the heat exchange fins of the cooling evaporator 17, and refrigerant temperature sensors that detect the temperature of the refrigerant flowing in the cooling evaporator 17.

[0078] The heater core temperature sensor 65 is a temperature detection unit that detects the temperature TH of the heater core 22. Examples of the heater core temperature sensor 65 include finned thermistors that detect the temperature of the heat exchange fins of the heater core 22, refrigerant temperature sensors that detect the temperature of the cooling water flowing in the heater core 22, and air temperature sensors that detect the temperature of the air flowing out of the heater core 22.

[0079] The refrigerant pressure sensor 66 is a refrigerant pressure detection unit that detects the pressure of the refrigerant discharged from the compressor 11. Instead of the refrigerant pressure sensor 66, a refrigerant temperature sensor can also be connected to the input side of the control device 60. The refrigerant temperature sensor is a refrigerant pressure detection unit that detects the temperature of the refrigerant discharged from the compressor 11. The control device 60 can also estimate the refrigerant pressure based on the refrigerant temperature.

[0080] The high-temperature cooling water temperature sensor 67 is a temperature detection unit that detects the temperature of the cooling water in the high-temperature cooling water circuit 20. For example, the high-temperature cooling water temperature sensor 67 detects the temperature of the cooling water in the condenser 12.

[0081] The low-temperature cooling water temperature sensor 68 is a temperature detection unit that detects the temperature of the cooling water in the low-temperature cooling water circuit 30. For example, the low-temperature cooling water temperature sensor 68 detects the temperature of the cooling water in the cooling evaporator 17.

[0082] The window surface humidity sensor 69 consists of a window near humidity sensor, a window near air temperature sensor, and a window surface temperature sensor.

[0083] The window-near humidity sensor detects the relative humidity of the air inside the vehicle interior near the windshield (hereinafter referred to as window-near relative humidity). The window-near air temperature sensor detects the temperature of the air inside the vehicle interior near the windshield. The window surface temperature sensor detects the surface temperature of the windshield.

[0084] Various operating switches (not shown) are connected to the input side of the control device 60. These operating switches are located on the control panel 70 and operated by the occupant. The control panel 70 is situated near the instrument panel at the front of the vehicle interior. Operating signals from the various operating switches are input to the control device 60.

[0085] The various control switches include the air conditioning switch and the temperature setting switch. The air conditioning switch determines whether the air is cooled by the indoor air conditioning unit 50. The temperature setting switch sets the desired temperature inside the vehicle.

[0086] Next, the operation of the above structure will be explained. The control device 60 switches the air conditioner's operating mode based on the target blowout temperature (TAO), etc. Figure 3 The cooling mode shown Figure 4 The heating mode shown and Figure 5 Any of the dehumidification and heating modes shown.

[0087] The target airflow temperature (TAO) is the target temperature of the air blown into the vehicle interior. The target airflow temperature (TAO) is an indicator representing the required air conditioning load (in other words, the air conditioning heat load) for the vehicle's air conditioning system 1. The control device 60 calculates the target airflow temperature (TAO) based on the following mathematical formula F1.

[0088] TAO=Kset×Tset-Kr×Tr-Kam×Tam-Ks×As+C...(F1)

[0089] In this mathematical formula, Tset is the interior set temperature set by the temperature setting switch on the operation panel 70, Tr is the interior air temperature detected by the interior air temperature sensor 61, Tam is the exterior air temperature detected by the exterior air temperature sensor 62, and As is the solar radiation detected by the solar radiation sensor 63. Kset, Kr, Kam, and Ks are control gains, and C is a constant used for correction.

[0090] If the control device 60 determines that the vehicle windows may fog up while in heating mode, it switches to dehumidification heating mode. For example, in heating mode, the control device 60 calculates the relative humidity RHW (hereinafter referred to as window surface relative humidity) of the interior surface of the vehicle based on the detection value of the window surface humidity sensor 69, and determines whether the vehicle windows may fog up based on the relative humidity RHW of the interior surface of the vehicle.

[0091] Window surface relative humidity (RHW) is an indicator of the likelihood of windshield fogging. Specifically, the higher the RHW value, the greater the likelihood of windshield fogging.

[0092] Next, the operation of the cooling mode, heating mode, and dehumidification heating mode will be explained.

[0093] (Cooling Mode)

[0094] In cooling mode, the control device 60 sets the first expansion valve 13 to a throttling state and the second expansion valve 16 to a fully closed state.

[0095] The control device 60 determines the operating status of various control devices connected to the control device 60 (control signals output to various control devices) based on the target blowing temperature TAO, the detection signals of the sensor group, etc.

[0096] The control signal output to the compressor 11 (in other words, the speed of the compressor 11) is determined by a feedback control method based on the deviation between the target evaporator temperature TEO and the temperature TE of the cooling evaporator 17, so that the temperature TE of the cooling evaporator 17 is close to the target evaporator temperature TEO.

[0097] The target evaporator temperature TEO is determined based on the target blow-out temperature TAO, with reference to a control mapping stored in the control device 60. In the control mapping of this embodiment, the target evaporator temperature TEO is determined such that it increases along with the increase of the target blow-out temperature TAO.

[0098] The control signal output to the indoor fan 53 (in other words, the air volume of the indoor fan 53) is determined based on the target outlet temperature TAO. For example, the control signal output to the indoor fan 53 is determined in a way that increases the air volume of the indoor fan 53 in both the high-temperature and low-temperature regions of the target outlet temperature TAO.

[0099] The control signal output to the first expansion valve 13 (in other words, the throttling opening of the first expansion valve 13) is determined in such a way as to make the superheat of the refrigerant flowing into the compressor 11 close to the target superheat, which is preset in such a way as to make the energy efficiency ratio (so-called COP) of the loop close to the maximum value.

[0100] The control signal output to the servo motor of the air mixing valve 54 is determined as follows: the air mixing valve 54 is operated to... Figure 3 The air passage of the heater core 22 is closed at the position shown, and the total flow of the supply air after passing through the air evaporator 14 flows around the air passage of the heater core 22.

[0101] In cooling mode, compressor 11 and high-temperature side pump 21 are activated. In cooling mode, on / off valve 24 opens the cooling water flow path on the high-temperature side radiator 23. Thus, in the high-temperature cooling water circuit 20, as... Figure 3 As shown by the thick solid line, cooling water circulates in the high-temperature side radiator 23, and heat is dissipated from the cooling water to the outside air in the radiator 23.

[0102] At this time, the cooling water of the high-temperature cooling water circuit 20 also circulates in the heater core 22. However, since the air mixing valve 54 closes the air passage of the heater core 22, almost no heat dissipation from the cooling water to the air occurs in the heater core 22.

[0103] In the refrigeration cycle unit 10 during cooling mode, such as Figure 3 As shown by the thick solid line, the state of the refrigerant circulating in the loop changes in the following manner.

[0104] That is, the high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12. The refrigerant flowing into the condenser 12 dissipates heat to the cooling water in the high-temperature cooling water circuit 20. Thus, the refrigerant is cooled and condensed in the condenser 12.

[0105] The refrigerant flowing from the condenser 12 flows into the first expansion valve 13, where it is depressurized and expands to become a low-pressure refrigerant. The low-pressure refrigerant, after being depressurized in the first expansion valve 13, flows into the air evaporator 14 and absorbs heat from the air supplied to the vehicle interior, thus evaporating. As a result, the air supplied to the vehicle interior is cooled.

[0106] Then, the refrigerant flowing out of the air evaporator 14 flows to the suction side of the compressor 11 and is compressed again in the compressor 11.

[0107] As described above, in cooling mode, low-pressure refrigerant absorbs heat from the air in the air evaporator 14, and the cooled air is then blown into the vehicle interior. This achieves cooling of the vehicle interior.

[0108] In cooling mode, when the battery 33 needs to be cooled, the second expansion valve 16 is set to a throttling state, and the low-temperature side pump 31 is activated.

[0109] Therefore, as Figure 3 As shown by the solid arrow, the refrigerant flowing from the condenser 12 flows into the second expansion valve 16, where it is depressurized and expands to become a low-pressure refrigerant. The low-pressure refrigerant, after being depressurized in the second expansion valve 16, flows into the cooling evaporator 17 and absorbs heat from the cooling water in the low-temperature cooling water circuit 30 to evaporate. Thus, the cooling water in the low-temperature cooling water circuit 30 is cooled.

[0110] In cases where cooling of battery 33 is required, such as Figure 3 As shown by the solid arrow, the three-way valve 38 is configured to circulate the cooling water of the low-temperature cooling water circuit 30 within the battery 33. Thus, the battery 33 is cooled by the cooling water from the low-temperature cooling water circuit 30.

[0111] (Heating mode)

[0112] In heating mode, the control device 60 sets the first expansion valve 13 to a fully closed state and the second expansion valve 16 to a throttling state.

[0113] The control device 60 determines the operating status of various control devices connected to the control device 60 (control signals output to various control devices) based on the target blowing temperature TAO, the detection signals of the sensor group, etc.

[0114] The control signal output to the compressor 11 (in other words, the speed of the compressor 11) is determined by a feedback control method based on the deviation between the target heater core temperature THO and the temperature TH of the heater core 22, so that the temperature TH of the heater core 22 is close to the target heater core temperature THO.

[0115] The target heater core temperature THO is determined based on the target blowout temperature TAO, referring to the control mapping stored in the control device 60. In the control mapping of this embodiment, the target heater core temperature THO is determined such that it increases as the target blowout temperature TAO increases.

[0116] The control signal output to the compressor 11 can also be determined based on the deviation between the target condenser temperature TCO and the temperature TC of the condenser 12, through a feedback control method, so that the temperature TC of the condenser 12 is close to the target condenser temperature TCO.

[0117] The control signal output to the indoor fan 53 (in other words, the airflow of the indoor fan 53) is determined based on the target outlet temperature (TAO), similar to the cooling mode. For example, the control signal output to the indoor fan 53 is determined in a way that increases the airflow of the indoor fan 53 in both the high-temperature and low-temperature regions of the target outlet temperature (TAO). Hereinafter, the airflow of the indoor fan 53 determined based on the target outlet temperature (TAO) will be referred to as the normal airflow.

[0118] During the warm-up process after the compressor 11 is started, the airflow of the indoor fan 53 is set to a warm-up airflow that is less than the normal airflow. This prevents cold air from being blown out to the occupants during warm-up, thus preventing the occupants from feeling cold.

[0119] That is, since the temperature of the blown air cannot be sufficiently increased during the warm-up of the refrigeration circulation device 10, causing the occupants to feel cold due to the blown air, the air volume of the indoor air supply fan 53 is determined to be a warm-up air volume that is less than the normal air volume.

[0120] For example, if the elapsed time after starting the compressor 11 is less than a specified time, the air volume of the indoor fan 53 can be determined as the heating air volume. Alternatively, if the temperature of the air blown out by the indoor air conditioning unit 50 is less than a specified temperature, the air volume of the indoor fan 53 can be determined as the heating air volume. Furthermore, if the temperature TH of the heater core 22 is less than a specified temperature, the air volume of the indoor fan 53 can be determined as the heating air volume.

[0121] The control signal output to the second expansion valve 16 is determined in such a way that the superheat of the refrigerant flowing out of the cooling evaporator 17 is close to a predetermined target superheat. The target superheat is determined in such a way that the energy efficiency ratio (COP) of the loop is close to its maximum value.

[0122] The control signal output to the servo motor of the air mixing valve 54 is determined as follows: the air mixing valve 54 is operated to... Figure 4The air passage of the heater core 22 is fully opened at the position shown, and the total flow rate of the supply air after passing through the air evaporator 14 passes through the air passage of the heater core 22.

[0123] In heating mode, compressor 11, high-temperature side pump 21, and low-temperature side pump 31 are activated. In heating mode, the on / off valve 24 closes the cooling water flow path on the high-temperature side radiator 23. Thus, as... Figure 4 As shown by the thick solid line in the high-temperature cooling water circuit 20, the cooling water in the high-temperature cooling water circuit 20 circulates in the heater core 22, and the cooling water dissipates heat from the air blown into the vehicle interior in the heater core 22.

[0124] In heating mode, the three-way valve 38 opens the cooling water flow path on the low-temperature side of the radiator 32. Thus, as... Figure 4 As shown by the thick solid line in the low-temperature cooling water circuit 30, the cooling water in the low-temperature side radiator 32 circulates.

[0125] In the refrigeration cycle unit 10 in heating mode, the refrigerant is as follows: Figure 4 As shown by the thick solid line, the refrigerant flows in a loop, and the state of the refrigerant changes in the following manner.

[0126] That is, the high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12 and exchanges heat with the cooling water in the high-temperature cooling water circuit 20 to dissipate heat. As a result, the cooling water in the high-temperature cooling water circuit 20 is heated.

[0127] The refrigerant flowing out of the condenser 12 flows into the second expansion valve 16 and is depressurized to become a low-pressure refrigerant. Then, the low-pressure refrigerant after being depressurized in the second expansion valve 16 flows into the cooling evaporator 17 and evaporates by absorbing heat from the cooling water in the low-temperature cooling water circuit 30.

[0128] Then, the refrigerant flowing out of the cooling evaporator 17 flows to the suction side of the compressor 11 and is compressed again in the compressor 11.

[0129] As described above, in heating mode, the heat from the high-pressure refrigerant discharged from the compressor 11 can be dissipated to the cooling water in the high-temperature cooling water circuit 20 in the condenser 12, and the heat from the cooling water in the high-temperature cooling water circuit 20 can be dissipated to the air in the heater core 22, and the air heated by the heater core 22 can be blown into the vehicle interior. Thus, heating of the vehicle interior can be achieved.

[0130] Since the cooling water in the low-temperature cooling water circuit 30 circulates in the low-temperature side radiator 32, the cooling water in the low-temperature cooling water circuit 30 can absorb heat from the outside air, and the low-pressure refrigerant in the cooling evaporator 17 can absorb heat from the cooling water in the low-temperature cooling water circuit 30. Therefore, the heat from the outside air can be used for heating inside the vehicle.

[0131] In the low-temperature cooling water circuit 30 of the heating mode, such as Figure 4 As shown by the solid arrow, by circulating the cooling water of the low-temperature cooling water circuit 30 in the battery 33, the cooling water of the low-temperature cooling water circuit 30 can absorb the waste heat of the battery 33, and the low-pressure refrigerant can absorb heat from the cooling water of the low-temperature cooling water circuit 30 in the cooling evaporator 17.

[0132] Therefore, the waste heat from the battery 33 can be used for heating the vehicle interior. Additionally, the waste heat from the battery 33 can be used for defrosting the low-temperature side radiator 32.

[0133] In addition, by circulating the cooling water of the low-temperature cooling water circuit 30 in the battery 33, the waste heat of the battery 33 can be used for heating or defrosting in the vehicle interior.

[0134] (Dehumidification and heating mode)

[0135] In dehumidification and heating mode, the control device 60 sets the first expansion valve 13 to a fully closed throttling state and the second expansion valve 16 to a fully closed state.

[0136] The control device 60 determines the operating status of various control devices connected to the control device 60 (control signals output to various control devices) based on the target blowing temperature TAO, the detection signals of the sensor group, etc.

[0137] The control signals output to the compressor 11 (in other words, the speed of the compressor 11) and the control signals output to the indoor fan 53 (in other words, the air volume of the indoor fan 53) are determined in the same way as the heating mode.

[0138] The control signal output to the first expansion valve 13 is determined in such a way that the superheat of the refrigerant flowing from the air evaporator 14 is close to a predetermined target superheat. The target superheat is determined in such a way that the energy efficiency ratio (COP) of the loop is close to its maximum value.

[0139] The control signal output to the servo motor of the air mixing valve 54 is determined as follows: the air mixing valve 54 is operated to... Figure 5 The air passage of the heater core 22 is fully opened at the position shown, and the total flow rate of the supply air through the air evaporator 14 passes through the air passage of the heater core 22.

[0140] In dehumidification and heating mode, compressor 11, high-temperature side pump 21, and low-temperature side pump 31 are activated.

[0141] In dehumidification and heating mode, the on / off valve 24 closes the cooling water flow path on the high-temperature side of the radiator 23. Therefore, in the high-temperature cooling water circuit 20 of dehumidification and heating mode, as... Figure 5 As shown by the thick solid line, the cooling water in the high-temperature cooling water circuit 20 circulates in the heater core 22, and the cooling water dissipates heat from the air blown into the vehicle interior in the heater core 22.

[0142] In the refrigeration cycle unit 10 in dehumidification and heating mode, the refrigerant is as follows: Figure 5 As shown by the thick solid line, the refrigerant flows in a loop, and the state of the refrigerant changes in the following manner.

[0143] That is, the high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12 and exchanges heat with the cooling water in the high-temperature cooling water circuit 20 to dissipate heat. As a result, the cooling water in the high-temperature cooling water circuit 20 is heated.

[0144] The refrigerant flowing from the condenser 12 flows into the first expansion valve 13 and is depressurized to become a low-pressure refrigerant. Then, the low-pressure refrigerant, depressurized in the first expansion valve 13, flows into the air evaporator 14 and evaporates by absorbing heat from the air supplied to the vehicle interior. Thus, the air supplied to the vehicle interior is cooled and dehumidified. Then, the refrigerant flowing from the air evaporator 14 flows to the suction side of the compressor 11 and is compressed again in the compressor 11.

[0145] As described above, in the dehumidification and heating mode, the heat of the high-pressure refrigerant discharged from the compressor 11 can be dissipated to the cooling water of the high-temperature cooling water circuit 20 in the condenser 12, and the heat of the cooling water of the high-temperature cooling water circuit 20 can be dissipated to the air in the heater core 22.

[0146] Furthermore, the low-pressure refrigerant, after being depressurized in the second expansion valve 16, can absorb heat from the air being blown into the vehicle interior in the air evaporator 14, and the air, after being cooled and dehumidified in the air evaporator 14, is heated in the heater core 22 and blown into the vehicle interior. Thus, dehumidification and heating of the vehicle interior can be achieved.

[0147] In dehumidification and heating mode, by setting the second expansion valve 16 to a throttling state, the low-pressure refrigerant after being depressurized in the second expansion valve 16 flows into the cooling evaporator 17 and absorbs heat from the cooling water in the low-temperature cooling water circuit 30 to evaporate.

[0148] Then, in the low-temperature cooling water circuit 30, such as Figure 5As shown by the thick solid line, by circulating the cooling water in the low-temperature cooling water circuit 30 within the low-temperature side radiator 32, the cooling water in the low-temperature cooling water circuit 30 can absorb heat from the outside air, and the low-pressure refrigerant can absorb heat from the cooling water in the low-temperature cooling water circuit 30 within the cooling evaporator 17. Therefore, the heat from the outside air can be used for heating inside the vehicle.

[0149] In addition, such as Figure 5 As shown by the solid arrow, by circulating the cooling water cooled in the cooling evaporator 17 into the battery 33, the cooling water in the low-temperature cooling water circuit 30 can absorb the waste heat from the battery 33, and the low-pressure refrigerant in the cooling evaporator 17 can absorb heat from the cooling water in the low-temperature cooling water circuit 30. Therefore, the waste heat from the battery 33 can be used for heating the vehicle interior.

[0150] Thus, in the vehicle air conditioning unit 1 of this embodiment, by switching the refrigerant flow to the air evaporator 14 and the cooling evaporator 17 with the cooling water flow in the high-temperature cooling water circuit 20 and the low-temperature cooling water circuit 30, appropriate cooling, heating and dehumidification heating in the vehicle interior can be performed, thereby achieving comfortable air conditioning in the vehicle interior.

[0151] (Battery cooling mode)

[0152] When the air conditioner is turned off and the battery 33 needs to be cooled, the control device 60 executes the battery cooling mode.

[0153] In battery cooling mode, control device 60 sets the first expansion valve 13 to fully closed state and the second expansion valve 16 to throttling state.

[0154] The control device 60 determines the operating status of various control devices connected to the control device 60 (control signals output to various control devices) based on the target temperature of the battery 33, the detection signals of the sensor group, etc.

[0155] The control signal output to the compressor 11 (in other words, the rotational speed of the compressor 11) is determined by a feedback control method based on the deviation between the target temperature of the battery 33 and the temperature of the battery 33, so that the temperature of the battery 33 is close to the target temperature.

[0156] The control signal output to the second expansion valve 16 is determined in such a way that the superheat of the refrigerant flowing out of the cooling evaporator 17 is close to a predetermined target superheat. The target superheat is determined in such a way that the energy efficiency ratio (COP) of the loop is close to its maximum value.

[0157] In battery cooling mode, compressor 11, high-temperature side pump 21, and low-temperature side pump 31 are activated. In battery cooling mode, the on / off valve 24 opens the cooling water flow path on the high-temperature side radiator 23. Thus, as... Figure 6 As shown by the thick solid line in the high-temperature cooling water circuit 20, the cooling water in the high-temperature cooling water circuit 20 circulates in the high-temperature side radiator 23, and dissipates heat from the cooling water to the outside air in the radiator 23.

[0158] In battery cooling mode, the three-way valve 38 circulates the cooling water in the low-temperature cooling water circuit 30 within the battery 33. Thus, the battery 33 is cooled by the cooling water in the low-temperature cooling water circuit 30.

[0159] In the refrigeration cycle unit 10 in battery cooling mode, the refrigerant is as follows: Figure 6 As shown by the thick solid line, the refrigerant flows in a loop, and the state of the refrigerant changes in the following manner.

[0160] That is, the high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12 and dissipates heat by exchanging heat with the cooling water in the high-temperature cooling water circuit 20. As a result, the refrigerant is cooled and condensed in the condenser 12.

[0161] The refrigerant flowing out of the condenser 12 flows into the second expansion valve 16 and is depressurized to become a low-pressure refrigerant. Then, the low-pressure refrigerant after being depressurized in the second expansion valve 16 flows into the cooling evaporator 17 and evaporates by absorbing heat from the cooling water in the low-temperature cooling water circuit 30.

[0162] Then, the refrigerant flowing out of the cooling evaporator 17 flows to the suction side of the compressor 11 and is compressed again in the compressor 11.

[0163] As described above, in the battery cooling mode, the cooling water in the low-temperature cooling water circuit 30 is cooled in the cooling evaporator 17, and the cooling water in the low-temperature cooling water circuit 30 circulates in the battery 33 to cool the battery 33.

[0164] Next, the oil recovery control in this embodiment will be explained. The control device 60 performs [operations] to prevent oil retention in the air evaporator 14. Figure 7 The flowchart illustrates the oil recovery control. Oil retention in the air evaporator 14 refers to the phenomenon where refrigerant mixed with the refrigerant remains in the air evaporator 14.

[0165] First, in step S100, it is determined whether the evaporator 17 is operating alone. That is, it is determined whether it is in heating mode or battery cooling mode. Specifically, if the refrigerant flow to the air evaporator 14 is cut off and the refrigerant flows to the cooling evaporator 17, it is determined that the evaporator 17 is operating alone.

[0166] If it is determined in step S100 that the evaporator 17 for cooling is operating alone, proceed to step S110 and set the previous residence time counter t. n-1 The value obtained by adding the value of dt to the specified value is determined as the residence time counter t for this period. n If the value of the evaporator 17 for cooling is not determined in step S100, proceed to step S150 and set the residence time counter t. n The value is reset to 0 and the process returns to step S100.

[0167] In step S120, the residence time counter t n The value is determined by whether it exceeds the threshold α1. In step S120, if the value is determined to be the residence time counter t, the residence time counter is determined to be the threshold α1. n If the value exceeds the threshold α1, it is determined that oil retention exists and the process proceeds to step S140. In step S120, when the retention amount counter t is determined to be... n If the value does not exceed the threshold α1, proceed to step S130 to determine whether the compressor 11 has changed from the stopped state to the started state.

[0168] If, in step S130, it is determined that the compressor 11 changes from a stopped state to a started state, then it is determined that oil retention exists and proceeds to step S140. If, in step S130, it is determined that the compressor 11 does not change from a stopped state to a started state, then it is determined that oil retention does not exist and returns to step S100.

[0169] In step S140, oil recovery control is performed. In the oil recovery control of step S140, as follows... Figure 8 As shown, firstly, in step S1410, the first expansion valve 13 is opened. As a result, since the refrigerant flows in the air evaporator 14, the refrigeration oil remaining in the air evaporator 14 can be returned to the compressor 11.

[0170] In this situation, if the first expansion valve 13 is periodically opened and closed, the refrigerant flow in the air evaporator 14 will pulsate, thus making it easier to recover the refrigeration oil retained in the air evaporator 14. Pulsating refrigerant flow in the air evaporator 14 can also be achieved by periodically increasing or decreasing the speed of the compressor 11.

[0171] At this time, if the opening degree of the first expansion valve 13 and the second expansion valve 16 is determined in such a way that the flow rate of refrigerant flowing into the air evaporator 14 is greater than the flow rate of refrigerant flowing into the cooling evaporator 17, the refrigeration oil retained in the air evaporator 14 can be effectively recovered.

[0172] If the opening degree of the first expansion valve 13 and the second expansion valve 16 is determined in such a way that the flow rate of refrigerant flowing into the cooling evaporator 17 is greater than the flow rate of refrigerant flowing into the air evaporator 14, then the reduction of heat absorption in the cooling evaporator 17 can be suppressed as much as possible.

[0173] In step S1420, the air that has passed through the air evaporator 14 can be heated in the heater core 22. Specifically, the indoor fan 53 and the high-temperature side pump 21 are operated, and the air mixing valve 54 is operated in a manner that opens the air passage of the heater core 22.

[0174] Therefore, it is possible to suppress the generation of unpleasant odors in the vehicle interior during oil recovery. That is, since the refrigerant flows in the air evaporator 14, the moisture in the air condenses or freezes in the air evaporator 14, which can easily generate odors. However, by heating the air after passing through the air evaporator 14 in the heater core 22, the relative humidity of the air after passing through the air evaporator 14 can be reduced, and the odor is less likely to be detected.

[0175] In step S1430, the second expansion valve 16 is set to the fully closed state, and the electric heater 25 is activated. As a result, the refrigerant flow rate in the air evaporator 14 increases, making it easier to recover the refrigerant oil retained in the air evaporator 14. By activating the electric heater 25, the decrease in the temperature of the air blown into the vehicle interior can be suppressed. That is, since the refrigerant does not flow in the cooling evaporator 17, resulting in a decrease in the heat absorbed in the cooling evaporator 17 and a decrease in the amount of cooling water heated in the condenser 12, activating the electric heater 25 can compensate for the decrease in the amount of cooling water heated in the condenser 12, thereby suppressing the decrease in the amount of air heated in the heater core 22.

[0176] In step S1440, the indoor / outdoor air switching door 52a is controlled in a manner that increases the internal air rate of the air introduced into the air conditioning housing 51, and the indoor air supply fan 53 is controlled in a manner that increases the air volume of the air introduced into the air conditioning housing 51.

[0177] As the internal air ratio of the air introduced into the air conditioning casing 51 increases, the temperature of the air flowing into the air evaporator 14 rises, thus increasing the heat exchange load of the air evaporator 14. The increased airflow into the air conditioning casing 51 also increases the heat exchange load of the air evaporator 14. With the increased heat exchange load of the air evaporator 14, the compressor 11 rotates at higher speeds, thereby increasing the refrigerant flow rate in the air evaporator 14, which facilitates the recovery of refrigeration oil retained in the air evaporator 14.

[0178] As the temperature of the air flowing into the air evaporator 14 rises, the temperature of the refrigeration oil remaining in the air evaporator 14 also rises, thereby reducing the viscosity of the refrigeration oil and making it easier to recover the refrigeration oil.

[0179] In step S1450, it is determined whether a predetermined time T1 (e.g., 10 seconds) has elapsed since the first expansion valve 13 was opened in step S1410. If it is determined in step S1450 that the predetermined time T1 has elapsed, the process proceeds to step S1460 and the oil recovery control ends. That is, the control state before the oil recovery control was executed is returned. If it is determined in step S1450 that the predetermined time T1 has not elapsed, step S1450 is repeated.

[0180] In this embodiment, the control device 60 performs oil recovery control when it determines that the first expansion valve 13 is closed and the refrigerant oil is trapped in the air evaporator 14. In the oil recovery control, the first expansion valve 13 is controlled by opening the refrigerant flow path.

[0181] In this way, since the refrigerant flows to the air evaporator 14 by opening the refrigerant flow path through the first expansion valve 13, the refrigeration oil remaining in the air evaporator 14 can be returned to the compressor 11.

[0182] In this embodiment, the control device 60 operates the indoor air supply fan 53 when performing oil recovery control. As a result, since the air cooled in the air evaporator 14 can be heated in the condenser 12 and blown into the vehicle interior space during oil recovery control, even if condensate is generated or the condensate freezes in the air evaporator 14 during oil recovery control, the relative humidity of the blown air can be reduced and the odor is less likely to be detected.

[0183] In this embodiment, when performing oil recovery control, the control device 60 performs at least one of speed control (in other words, discharge capacity control) that increases or decreases the speed of the compressor 11 (in other words, the refrigerant discharge capacity) and opening control that increases or decreases the opening of the first expansion valve 13.

[0184] Therefore, by pulsating the refrigerant flowing in the air evaporator 14 during oil recovery control, the refrigeration oil remaining in the air evaporator 14 can be effectively returned to the compressor 11.

[0185] In this embodiment, when performing oil recovery control, the control device 60 controls the first expansion valve 13 and the second expansion valve 16 in such a way that the flow rate of refrigerant flowing into the air evaporator 14 is greater than the flow rate of refrigerant flowing into the cooling evaporator 17.

[0186] This allows for maximizing the flow rate of refrigerant in the air evaporator 14, thereby effectively returning the refrigeration oil retained in the air evaporator 14 to the compressor 11.

[0187] In this embodiment, the control device 60 operates the electric heater 25 when performing oil recovery control. Therefore, even if the flow rate of refrigerant into the cooling evaporator 17 decreases, resulting in less heat absorption in the cooling evaporator 17 and consequently less heat dissipation from the refrigerant to the cooling water in the condenser 12, the Joule heat from the electric heater 25 can compensate for the heat dissipation to the cooling water. Thus, the blown-out air temperature can be maintained as much as possible during oil recovery control.

[0188] In this embodiment, when performing oil recovery control, the control device 60 controls the first expansion valve 13 and the second expansion valve 16 in such a way that the flow rate of refrigerant flowing into the cooling evaporator 17 is greater than the flow rate of refrigerant flowing into the air evaporator 14.

[0189] Therefore, since the reduction in the refrigerant flow into the cooling evaporator 17 during oil recovery can be minimized, the reduction in heat absorption in the cooling evaporator 17 can be minimized. Consequently, since the reduction in heat dissipation from the refrigerant in the condenser 12 can be minimized, fluctuations in the blow-out air temperature during oil recovery control can be minimized.

[0190] In this embodiment, if the first expansion valve 13 is closed for a predetermined time or longer, the control device 60 determines that the refrigerant oil is trapped in the air evaporator 14. Therefore, it is possible to appropriately determine whether the refrigerant oil is trapped in the air evaporator 14.

[0191] In this embodiment, the control device 60 performs oil recovery control when the compressor 11 changes from a stopped state to a started state and the first expansion valve 13 closes its flow path. As a result, the refrigerant flows back to the air evaporator 14 during the period when the compressor 11 is stopped, thereby enabling the refrigeration oil remaining in the air evaporator 14 to quickly return to the compressor 11.

[0192] In this embodiment, the control device 60 increases the speed of the compressor 11 by increasing the heat exchange load of the air evaporator 14, and controls the internal and external air switching door 52a in such a way that the ratio of internal air to external air is greater when oil recovery control is performed.

[0193] In this way, since the heat exchange load of the air evaporator 14 can be increased during oil recovery control, the flow rate of the refrigerant discharged from the compressor 11 can be increased. Therefore, the flow rate of the refrigerant flowing into the air evaporator 14 can be increased, thereby effectively returning the refrigeration oil retained in the air evaporator 14 to the compressor 11.

[0194] Since the viscosity of the refrigeration oil retained in the air evaporator 14 can be reduced by increasing the temperature of the air flowing into the air evaporator 14, the refrigeration oil retained in the air evaporator 14 can be effectively returned to the compressor 11.

[0195] In this embodiment, when the control device 60 performs oil recovery control, it increases the airflow of the indoor fan 53 compared to the normal airflow. As a result, since the heat exchange load of the air evaporator 14 can be increased during oil recovery control, the discharge refrigerant flow of the compressor 11 can be increased. Therefore, the flow of refrigerant flowing into the air evaporator 14 can be increased, thereby effectively returning the refrigeration oil retained in the air evaporator 14 to the compressor 11.

[0196] (Second Implementation)

[0197] In the above embodiment, oil recovery control is performed when oil is present in the air evaporator 14. However, in this embodiment, oil recovery control is performed when oil is present in the air evaporator 14 and the refrigeration cycle device 10 is in warm-up mode.

[0198] To prevent oil from accumulating in the air evaporator 14, control device 60 performs... Figure 9 The flowchart illustrates the oil recovery control. Figure 9 In the flowchart, regarding the first embodiment described above Figure 7 Add step S135 to the flowchart.

[0199] In step S120, when the dwell time counter t is determined to be... n If the threshold α1 is exceeded, it is determined that oil retention exists and the process proceeds to step S135. In step S120, when the retention amount counter t is determined to be present... nIf the threshold α1 is not exceeded, proceed to step S130 to determine whether the compressor 11 has changed from a stopped state to a started state. If it is determined in step S130 that the compressor 11 has changed from a stopped state to a started state, it is determined that oil retention exists and proceed to step S135. If it is determined in step S130 that the compressor 11 has not changed from a stopped state to a started state, it is determined that oil retention does not exist and return to step S100.

[0200] In step S135, it is determined whether the airflow of the indoor air supply fan 53 is controlled below the warm-up airflow. If it is determined in step S135 that the airflow of the indoor air supply fan 53 is controlled at the warm-up airflow, the process proceeds to step S140 and oil recovery control is performed. Therefore, since oil recovery control is performed when the airflow of the indoor air supply fan 53 is low, it is possible to prevent the generation of condensate or freezing of condensate in the air evaporator 14 during oil recovery, thus suppressing the generation of unpleasant odors in the vehicle interior. Since oil recovery is performed without increasing the airflow to the air evaporator 14, oil recovery can be performed without delaying the warm-up of the refrigeration cycle device 10.

[0201] In step S135, if it is determined that the air volume of the indoor air supply fan 53 is not controlled to the warm air volume, it is determined that an unpleasant odor may be generated in the vehicle interior during oil recovery, so oil recovery is not performed and the process returns to step 100.

[0202] In this embodiment, the control device 60 performs oil recovery control when it determines that the refrigeration oil is trapped in the air evaporator 14 and the indoor fan 53 is controlled to the warm air volume.

[0203] Therefore, since the generation of condensate or freezing of condensate in the air evaporator 14 can be suppressed during oil recovery control, the generation of odor in the air evaporator 14 can be suppressed.

[0204] (Third Implementation)

[0205] In the above embodiments, oil recovery control is performed when the compressor 11 starts. However, in this embodiment, the purpose is to eliminate the need for oil recovery control during compressor 11 startup. Figure 10 As shown, a backflow prevention valve 19 is provided on the refrigerant outlet side of the air evaporator 14.

[0206] The backflow prevention valve 19 is a backflow prevention unit that prevents the refrigerant stored in the storage tank 18 from flowing back into the air evaporator 14 after the compressor 11 stops.

[0207] The backflow prevention valve 19 is located downstream of the refrigerant flow in the air evaporator 14 and upstream of the refrigerant flow in the confluence section 10b. The backflow prevention valve 19 allows refrigerant to flow from the air evaporator 14 toward the confluence section 10b and prevents refrigerant from flowing from the confluence section 10b toward the air evaporator 14.

[0208] Because the pressure difference is small during backflow, it is desirable that the backflow prevention valve 19 be a spring-loaded check valve that closes the valve core using the force of a spring during backflow. The backflow prevention valve 19 can also be a solenoid valve controlled by the control device 60.

[0209] In this embodiment, since it is possible to prevent the refrigerant stored in the storage tank 18 from flowing back into the air evaporator 14 after the compressor 11 stops, it is possible to suppress the refrigeration oil from remaining in the air evaporator 14 due to the refrigerant flowing back into the air evaporator 14.

[0210] In this embodiment, the backflow prevention valve 19 allows refrigerant to flow from the air evaporator 14 toward the confluence section 10b, and prevents refrigerant from flowing from the confluence section 10b toward the air evaporator 14.

[0211] Therefore, it is possible to suppress the reduction of refrigeration oil remaining in the air evaporator 14 due to the refrigerant flowing back into the air evaporator 14 during the period when the compressor 11 is stopped.

[0212] This disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of this disclosure as described below.

[0213] In the above embodiments, cooling water is used as the heat medium, but various media such as oil can also be used. Nanofluids can also be used as the heat medium. A nanofluid is a fluid incorporating nanoparticles with a particle size in the nanometer range.

[0214] In the refrigeration cycle apparatus 10 of the above embodiment, Freon-type refrigerants are used as refrigerants, but the type of refrigerant is not limited to this, and natural refrigerants such as carbon dioxide or hydrocarbon refrigerants may also be used.

[0215] In addition, the refrigeration cycle 10 of the above embodiment constitutes a subcritical refrigeration cycle in which the refrigerant pressure on the high-pressure side does not exceed the critical pressure of the refrigerant, but it can also constitute a supercritical refrigeration cycle in which the refrigerant pressure on the high-pressure side exceeds the critical pressure of the refrigerant.

[0216] In the above embodiments, the high-temperature side heat sink 23 and the low-temperature side heat sink 32 are different heat sinks, but the high-temperature side heat sink 23 and the low-temperature side heat sink 32 can also be composed of a single heat sink.

[0217] For example, the high-temperature side radiator 23 and the low-temperature side radiator 32 can be integrated into one radiator.

[0218] In the above embodiment, the first expansion valve 13 is integrally configured with a pressure reducing section for reducing the pressure of the refrigerant and an opening regulating section for regulating the opening degree of the refrigerant flow path, but the pressure reducing section and the opening regulating section may also be separate.

[0219] While this disclosure has been described based on embodiments, it should be understood that this disclosure is not limited to the above embodiments and structures. This disclosure also includes various modifications and equivalent variations. Furthermore, various combinations and arrangements, and consequently, combinations and arrangements containing only one element, or more than or less thereof, also fall within the scope and spirit of this disclosure.

Claims

1. A refrigeration cycle device, comprising: A compressor that draws in refrigerant and discharges it after compression; The heat dissipation unit dissipates heat to the air by exchanging heat between the refrigerant discharged from the compressor and the air supplied to the air-conditioned space. A first pressure-reducing section is capable of reducing the pressure of the refrigerant and closing the flow path of the refrigerant; The first evaporation section evaporates the refrigerant by exchanging heat between the refrigerant, which has been depressurized in the first depressurization section, and the air, and by absorbing heat from the air. The second pressure reducing unit is arranged in parallel with the first pressure reducing unit in the flow path of the refrigerant, and reduces the pressure of the refrigerant. The second evaporation section evaporates the refrigerant by causing the refrigerant, after being depressurized in the second depressurization section, to absorb heat. The control unit determines that the first pressure reducing unit closes the flow path and the refrigeration oil mixed with the refrigerant remains in the first evaporation unit, and then performs oil recovery control of the first pressure reducing unit in a manner that opens the flow path. as well as A blower that directs air to the first evaporation section and the heat dissipation section. The control unit determines the air volume of the blower corresponding to the air conditioning load, i.e., the normal air volume. If it is determined that the blown air temperature cannot be set above the specified temperature when the compressor is started, the air volume of the blower is set to a warm-up air volume that is lower than the normal air volume. If it is determined that the refrigeration oil is stagnant in the first evaporator and the blower is controlled to the warm-up airflow, the oil recovery control is executed.

2. The refrigeration cycle apparatus as described in claim 1, characterized in that, The refrigeration cycle device includes a blower that supplies air to the first evaporator and the heat dissipation unit. The heat dissipation unit is disposed downstream of the first evaporation unit in the airflow path. When performing oil recovery control, the control unit activates the blower.

3. The refrigeration cycle apparatus as described in claim 1, characterized in that, When performing the oil recovery control, the control unit performs at least one of discharge capacity control, which increases or decreases the refrigerant discharge capacity of the compressor, and opening control, which increases or decreases the opening degree of the first pressure reducing unit.

4. The refrigeration cycle apparatus as described in claim 1, characterized in that, As a heat source for heating the air in the heat dissipation section, a Joule heating section is included to generate Joule heat. When performing the oil recovery control, the control unit controls the Joule heat generating unit in a manner that generates the Joule heat.

5. The refrigeration cycle apparatus according to any one of claims 1 to 4, characterized in that, If the control unit determines that the refrigeration oil is stagnant in the first evaporation unit when the first pressure reducing unit is closed for more than a specified time, the control unit determines that the refrigeration oil is stagnant in the first evaporation unit.

6. The refrigeration cycle apparatus according to any one of claims 1 to 4, characterized in that, The control unit performs the oil recovery control when the compressor changes from a stopped state to a started state and the first pressure reducing unit closes the flow path.

7. The refrigeration cycle apparatus according to any one of claims 1 to 4, characterized in that, The refrigeration cycle device includes: A confluence section, wherein the refrigerant flowing from the first pressure-reducing section merges with the refrigerant flowing from the second pressure-reducing section; and A backflow prevention section is provided, which is located downstream of the refrigerant flow in the first evaporator and upstream of the refrigerant flow in the confluence section, allowing the refrigerant to flow from the first evaporator toward the confluence section and preventing the refrigerant from flowing from the confluence section toward the first evaporator.

8. The refrigeration cycle apparatus according to any one of claims 1 to 4, characterized in that, The refrigeration cycle device includes an internal and external air conditioning unit that adjusts the ratio of internal air to external air in the air flowing into the first evaporator. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. When the oil recovery control is performed, the internal and external air conditioning units are controlled in such a way that the ratio of internal air is greater than the ratio of external air.

9. The refrigeration cycle apparatus according to any one of claims 1 to 4, characterized in that, The refrigeration cycle device includes a blower for supplying air. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. Determine the air volume of the supply fan corresponding to the air conditioning load, i.e., the normal air volume. When the oil recovery control is implemented, the air volume of the blower is increased compared to the normal air volume.

10. A refrigeration cycle apparatus, comprising: A compressor that draws in refrigerant and discharges it after compression; The heat dissipation unit dissipates heat to the air by exchanging heat between the refrigerant discharged from the compressor and the air supplied to the air-conditioned space. A first pressure-reducing section is capable of reducing the pressure of the refrigerant and closing the flow path of the refrigerant; The first evaporation section evaporates the refrigerant by exchanging heat between the refrigerant, which has been depressurized in the first depressurization section, and the air, and by absorbing heat from the air. The second pressure reducing unit is arranged in parallel with the first pressure reducing unit in the flow path of the refrigerant, and reduces the pressure of the refrigerant. The second evaporation section evaporates the refrigerant by causing the refrigerant, after being depressurized in the second depressurization section, to absorb heat. The control unit determines that the first pressure reducing unit closes the flow path and the refrigeration oil mixed with the refrigerant remains in the first evaporation unit, and then performs oil recovery control of the first pressure reducing unit in a manner that opens the flow path. as well as The Joule heating unit serves as a heat source for heating the air in the heat dissipation unit and generates Joule heat. When performing the oil recovery control, the control unit controls the Joule heat generating unit in a manner that generates the Joule heat.

11. The refrigeration cycle apparatus as described in claim 10, characterized in that, If the control unit determines that the refrigeration oil is stagnant in the first evaporation unit when the first pressure reducing unit is closed for more than a specified time, the control unit determines that the refrigeration oil is stagnant in the first evaporation unit.

12. The refrigeration cycle apparatus as described in claim 10, characterized in that, The control unit performs the oil recovery control when the compressor changes from a stopped state to a started state and the first pressure reducing unit closes the flow path.

13. The refrigeration cycle apparatus according to any one of claims 10 to 12, characterized in that, The refrigeration cycle device includes: A confluence section, wherein the refrigerant flowing from the first pressure-reducing section merges with the refrigerant flowing from the second pressure-reducing section; and A backflow prevention section is provided, which is located downstream of the refrigerant flow in the first evaporator and upstream of the refrigerant flow in the confluence section, allowing the refrigerant to flow from the first evaporator toward the confluence section and preventing the refrigerant from flowing from the confluence section toward the first evaporator.

14. The refrigeration cycle apparatus according to any one of claims 10 to 12, characterized in that, The refrigeration cycle device includes an internal and external air conditioning unit that adjusts the ratio of internal air to external air in the air flowing into the first evaporator. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. When the oil recovery control is performed, the internal and external air conditioning units are controlled in such a way that the ratio of internal air is greater than the ratio of external air.

15. The refrigeration cycle apparatus according to any one of claims 10 to 12, characterized in that, The refrigeration cycle device includes a blower for supplying air. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. Determine the air volume of the supply fan corresponding to the air conditioning load, i.e., the normal air volume. When the oil recovery control is implemented, the air volume of the blower is increased compared to the normal air volume.

16. A refrigeration cycle apparatus, comprising: A compressor that draws in refrigerant and discharges it after compression; The heat dissipation unit dissipates heat to the air by exchanging heat between the refrigerant discharged from the compressor and the air supplied to the air-conditioned space. A first pressure-reducing section is capable of reducing the pressure of the refrigerant and closing the flow path of the refrigerant; The first evaporation section evaporates the refrigerant by exchanging heat between the refrigerant, which has been depressurized in the first depressurization section, and the air, and by absorbing heat from the air. The second pressure reducing unit is arranged in parallel with the first pressure reducing unit in the flow path of the refrigerant, and reduces the pressure of the refrigerant. The second evaporation section evaporates the refrigerant by causing the refrigerant, after being depressurized in the second depressurization section, to absorb heat. The control unit determines that the first pressure reducing unit closes the flow path and the refrigeration oil mixed with the refrigerant remains in the first evaporation unit, and then performs oil recovery control of the first pressure reducing unit in a manner that opens the flow path. as well as An internal and external air conditioning unit adjusts the ratio of internal air to external air in the air flowing into the first evaporator. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. When the oil recovery control is performed, the internal and external air conditioning units are controlled in such a way that the ratio of internal air is greater than the ratio of external air.

17. The refrigeration cycle apparatus as claimed in claim 16, characterized in that, The refrigeration cycle device includes a blower for supplying air. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. Determine the air volume of the supply fan corresponding to the air conditioning load, i.e., the normal air volume. When the oil recovery control is implemented, the air volume of the blower is increased compared to the normal air volume.

18. A refrigeration cycle apparatus, comprising: A compressor that draws in refrigerant and discharges it after compression; The heat dissipation unit dissipates heat to the air by exchanging heat between the refrigerant discharged from the compressor and the air supplied to the air-conditioned space. A first pressure-reducing section is capable of reducing the pressure of the refrigerant and closing the flow path of the refrigerant; The first evaporation section evaporates the refrigerant by exchanging heat between the refrigerant, which has been depressurized in the first depressurization section, and the air, and by absorbing heat from the air. The second pressure reducing unit is arranged in parallel with the first pressure reducing unit in the flow path of the refrigerant, and reduces the pressure of the refrigerant. The second evaporation section evaporates the refrigerant by causing the refrigerant, after being depressurized in the second depressurization section, to absorb heat. The control unit determines that the first pressure reducing unit closes the flow path and the refrigeration oil mixed with the refrigerant remains in the first evaporation unit, and then performs oil recovery control of the first pressure reducing unit in a manner that opens the flow path. as well as A blower that supplies air to the system. The higher the heat exchange load of the first evaporator section, the higher the refrigerant discharge capacity of the compressor. Determine the air volume of the supply fan corresponding to the air conditioning load, i.e., the normal air volume. When the oil recovery control is implemented, the air volume of the blower is increased compared to the normal air volume.

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