CN117836160A - Air conditioner for vehicle - Google Patents

Abstract

The present invention ensures sufficient heating capacity without using an auxiliary heater. The present invention provides an air conditioner for a vehicle, comprising: a refrigerant circuit comprising: a compressor for compressing a refrigerant; an indoor heat exchanger for exchanging heat between heat of the refrigerant compressed by the compressor and air supplied into the vehicle interior; and a heat exchanger for absorbing heat, wherein the heat exchanger exchanges heat between the refrigerant and outside air or other heat medium; and a control device that controls the refrigerant circuit, the refrigerant circuit having a hot-gas circuit that bypasses the heat exchanger and flows refrigerant from a downstream side of the indoor heat exchanger to a suction side of the compressor, the control device being capable of selectively executing a plurality of heating modes including a hot-gas heating mode that circulates the refrigerant in the hot-gas circuit and heats the interior of the vehicle compartment by heat of the refrigerant compressed by the compressor without heat exchange between the refrigerant and outside air or other heat medium in the heat exchanger, the control device setting a hot-gas heating selection condition that selects the hot-gas heating mode.

Description

Air conditioner for vehicle

Technical Field

The present invention relates to a heat pump type air conditioner for a vehicle applied to a vehicle, and more particularly to a vehicle air conditioner having a plurality of operation modes for heating operation.

Background

Conventionally, there is known a heat pump type air conditioner for a vehicle, which is provided with a refrigerant circuit to which a compressor, an indoor heat exchanger, an outdoor heat exchanger, and an expansion valve are connected, and which supplies air, which has undergone heat exchange between the indoor heat exchanger and a refrigerant, into a vehicle interior to perform air conditioning in the vehicle interior.

In such a vehicle air conditioning apparatus, the outdoor heat exchanger functions as a heat absorber during the heating operation, but if the outside air temperature is extremely low (extremely low temperature environment), the refrigerant may not absorb heat from the outside air in the outdoor heat exchanger. In this case, for example, an auxiliary heater such as a PTC heater is used to heat air supplied into the vehicle interior to supplement the heating operation (for example, patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2020-97363

Disclosure of Invention

Technical problem to be solved by the invention

However, since the auxiliary heater such as the PTC heater is expensive, the manufacturing cost of the air conditioner for a vehicle increases. Therefore, it is desired that the auxiliary heater be omitted in the vehicular air conditioner to ensure necessary heating capacity even in the case where the heat absorbing heat medium is not present in an extremely low temperature environment or the like.

The present invention has been made in view of such circumstances, and an object thereof is to ensure sufficient heating capacity and the like without using an auxiliary heater.

Technical scheme for solving technical problems

One aspect of the present invention provides an air conditioner for a vehicle, comprising: a refrigerant circuit comprising: a compressor for compressing a refrigerant; an indoor heat exchanger for exchanging heat between heat of the refrigerant compressed by the compressor and air supplied into the vehicle interior; and a heat exchanger for absorbing heat, wherein the heat exchanger exchanges heat between the refrigerant and outside air or other heat medium; and a control device that controls the refrigerant circuit, the refrigerant circuit having a hot-gas circuit that bypasses the heat exchanger and flows refrigerant from a downstream side of the indoor heat exchanger to a suction side of the compressor, the control device being capable of selectively executing a plurality of heating modes including a hot-gas heating mode that circulates the refrigerant in the hot-gas circuit and heats the interior of the vehicle compartment by heat of the refrigerant compressed by the compressor without heat exchange between the refrigerant and outside air or other heat medium in the heat exchanger, the control device setting a hot-gas heating selection condition that selects the hot-gas heating mode.

Effects of the invention

According to the present invention, a sufficient heating capacity can be ensured without using an auxiliary heater.

Drawings

Fig. 1 is a schematic diagram showing a configuration of a refrigerant circuit of an air conditioner for a vehicle according to a first embodiment of the present invention.

Fig. 2 is a block diagram showing a schematic configuration of a heat pump ECU as a control device of a vehicle air conditioner according to a first embodiment of the present invention.

Fig. 3 is a diagram showing the flow of the refrigerant in the case of performing the heating operation in the outside air heat absorption heating mode in the vehicular air conditioning apparatus according to the first embodiment of the present invention.

Fig. 4 is a diagram showing the flow of the refrigerant in the case of performing the heating operation in the hot-air heating mode in the vehicle air conditioner according to the first embodiment of the present invention.

Fig. 5 is a flowchart showing a flow of a heating mode selection process in the air conditioner for a vehicle according to the first embodiment of the present invention.

Fig. 6 is a schematic diagram showing a configuration of a refrigerant circuit of an air conditioner for a vehicle according to a second embodiment of the present invention.

Fig. 7 is a block diagram showing a schematic configuration of a heat pump ECU as a control device of a vehicle air conditioner according to a second embodiment of the present invention.

Fig. 8 is a diagram showing the flow of refrigerant in the case where the heating operation is performed in the first hot-air heating mode in the air conditioning apparatus for a vehicle according to the second embodiment of the present invention.

Fig. 9 is a diagram showing the flow of refrigerant in the case where the heating operation is performed in the second hot-air heating mode in the air conditioning apparatus for a vehicle according to the second embodiment of the present invention.

Fig. 10 is a flowchart showing a flow of a heating mode selection process in the air conditioner for a vehicle according to the second embodiment of the present invention.

Fig. 11 is a flowchart showing a flow of a heating mode selection process in the vehicular air conditioner according to the modification of the second embodiment of the present invention.

Fig. 12 is a flowchart showing a flow of heating mode switching processing in a heating operation using any one of heating modes in the air conditioner for a vehicle according to the third embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals denote parts having the same functions, and repetitive description in the drawings will be omitted as appropriate.

(first embodiment)

Fig. 1 shows a schematic configuration of a vehicle air conditioner 100 according to a first embodiment of the present invention. The vehicle air conditioner 100 is applied to, for example, a vehicle such as an Electric Vehicle (EV) that does not mount an engine (internal combustion engine) or a so-called hybrid vehicle that uses both an engine and an electric motor for running. Such a vehicle is equipped with a battery (for example, a lithium battery), and is driven by supplying electric power charged from an external power source to a motor unit including an electric motor for running. The vehicle air conditioner 100 is also driven by electric power supplied from the battery.

The vehicle air conditioner 100 according to the present embodiment includes the refrigerant circuit R, and performs air conditioning (heating, cooling, dehumidification, and defrosting) of the vehicle interior by performing a heat pump operation using the refrigerant circuit R. In the following description, the refrigerant is a circulation medium of the refrigerant circuit that accompanies a state change of the heat pump (compression, condensation, expansion, and evaporation), and the heat medium is a medium that absorbs and releases heat without accompanying such a state change.

The refrigerant circuit R is configured by connecting an electric compressor 2 that compresses a refrigerant through refrigerant pipes 13A to 13H, an indoor heat exchanger 4 that is provided in an air flow path 3 of an HAVC unit 10 that circulates air in a vehicle interior and that releases heat from a high-temperature and high-pressure refrigerant discharged from the compressor 2 to heat air supplied into the vehicle interior, an outdoor expansion valve 6 that decompresses and expands the refrigerant during heating, an outdoor heat exchanger 7 that performs heat exchange between the refrigerant and outside air in order to function as a radiator (condenser) that releases heat of the refrigerant during cooling and as an evaporator that releases heat of the refrigerant during heating, an indoor expansion valve 8 that performs decompression and expansion of the refrigerant, a heat absorber 9 that is provided in the air flow path 3 and that absorbs heat from the inside and outside of the vehicle interior during cooling and cools air supplied into the vehicle interior during cooling and an accumulator 12, and the like.

The outdoor expansion valve 6 and the indoor expansion valve 8 are both electronic expansion valves driven by a pulse motor, not shown, and the opening degree is appropriately controlled between full-closed and full-open according to the number of pulses applied to the pulse motor. The outdoor expansion valve 6 decompresses and expands the refrigerant flowing out of the indoor heat exchanger 4 and into the outdoor heat exchanger 7 during the heating operation and the defrosting operation using the outdoor heat exchanger 7. In addition, during the cooling operation, the solenoid valve 21 is opened, and the refrigerant passes through the solenoid valve 21 without passing through the outdoor expansion valve 6. The electromagnetic valve 21 and the outdoor expansion valve 6 may be constituted by one electronic expansion valve. The indoor expansion valve 8 decompresses and expands the refrigerant flowing into the heat absorber 9, and adjusts the superheat degree of the refrigerant in the heat absorber 9.

Further, a check valve 20, a receiver 12, and a compressor 2 are connected in this order to the refrigerant pipe 13A from the outdoor heat exchanger 7. The refrigerant pipe 13A branches into a refrigerant pipe 13B between the outlet side of the check valve 20 and the inlet side of the accumulator 12. The refrigerant pipe 13B connects the outlet side of the check valve 20 to the outlet side of the indoor heat exchanger 4. That is, the refrigerant pipe 13B is connected in parallel with the outdoor heat exchanger 7, and connects the outlet side of the outdoor heat exchanger 7 to the outlet side of the indoor heat exchanger 4, thereby forming a hot gas circuit bypassing the outdoor heat exchanger 7. The electromagnetic valve 22 is provided in the refrigerant pipe 13B, and whether or not the refrigerant is to flow into the refrigerant pipe 13B, that is, whether or not the hot gas circuit is to be used can be selected according to the opening and closing of the electromagnetic valve 22. The solenoid valve 22 may be an electronic expansion valve.

The refrigerant pipe 13B branches into a refrigerant pipe 13C on the side of the check valve 20 with respect to the solenoid valve 22, and the refrigerant pipe 13C is connected to the heat absorber 9 in refrigerant communication. An indoor expansion valve 8 is provided near the inlet of the heat absorber 9 of the refrigerant pipe 13C. The refrigerant outlet of the heat absorber 9 is connected to the refrigerant inlet of the accumulator 12 of the refrigerant pipe 13A through the check valve 23 by the refrigerant pipe 13D. The refrigerant outlet of the accumulator 12 is connected to the refrigerant inlet of the compressor 2 through a refrigerant pipe 13E, and a compressor sensor 72 is provided in the refrigerant pipe 13E, and the compressor sensor 72 detects the pressure of the refrigerant sucked into the compressor 2 (suction pressure) and the suction refrigerant temperature of the compressor 2.

The refrigerant outlet of the compressor 2 and the refrigerant inlet of the indoor heat exchanger 4 are connected by a refrigerant pipe 13F. One end of the refrigerant pipe 13G is connected to the refrigerant outlet of the indoor heat exchanger 4, and the other end of the refrigerant pipe 13G is connected to the refrigerant inlet of the outdoor heat exchanger 7 via the solenoid valve 21. The refrigerant pipe 13G branches into a refrigerant pipe 13H so as to bypass the solenoid valve 21. The refrigerant pipe 13H is provided with an outdoor expansion valve 6, and the refrigerant pipe 13H merges with the refrigerant pipe 13G via the outdoor expansion valve 6.

The air flow path 3 on the air upstream side of the heat absorber 9 has an outside air intake port and each intake port of the inside air intake port. A suction switching damper 26 is provided at the suction port. The air flow path 3 is introduced from the intake port by appropriately switching the inside air (inside air circulation) as the air in the vehicle interior and the outside air (outside air introduction) as the air outside the vehicle interior by the intake switching damper 26. A blower (fan) 27 for supplying the introduced inside air and outside air to the air flow path 3 is provided on the air downstream side of the suction switching damper 26.

An air mixing damper 28 is provided in the air flow path 3 on the air upstream side of the indoor heat exchanger 4, and the air mixing damper 28 adjusts the ratio of ventilation of the air (inside air, outside air) flowing into the air flow path 3 and passing through the heat absorber 9 into the indoor heat exchanger 4.

As an auxiliary heating method, for example, the following method may be adopted: the warm water heated by the compressor waste heat is circulated through the heater core disposed in the air flow path 3, thereby heating the air to be sent.

Fig. 2 shows a schematic configuration of a heat pump ECU (HP ECU) 11 as a control device of the vehicle air conditioner 100. The heat pump ECU11 and the vehicle controller 90 responsible for controlling the entire vehicle including running are communicably connected to each other through a vehicle-mounted network such as CAN (controller area network (Controller Area Network)), LIN (local interconnect network (Local Interconnect Network)), or the like, and transmit and receive information. The heat pump ECU11 and the vehicle controller 90 can be microcomputers, which are examples of computers equipped with processors.

The following sensors and detectors are connected to the heat pump ECU11, and outputs of the sensors and detectors are input to the heat pump ECU11. In fig. 2 and the following description, the sensor and the detector which are not directly related to the present embodiment are not shown and described.

An outside air temperature sensor 71 that detects the outside air temperature of the vehicle, a compressor sensor 72 that detects the pressure of the refrigerant sucked into the compressor 2 (suction pressure) and the suction refrigerant temperature of the compressor 2, an indoor heat exchanger sensor 73 that detects the temperature of the indoor heat exchanger 4 and the pressure of the indoor heat exchanger 4 (for example, the pressure of the refrigerant immediately after being discharged from the indoor heat exchanger 4), an outdoor heat exchanger sensor 74 that detects the temperature of the outdoor heat exchanger 7 (for example, the temperature of the refrigerant immediately after being discharged from the outdoor heat exchanger 7) and the pressure of the refrigerant of the outdoor heat exchanger 7 (for example, the pressure of the refrigerant immediately after being discharged from the outdoor heat exchanger 7), and an air-conditioning operation unit 75 that sets switching between a set temperature and an air-conditioning operation are connected to the heat pump ECU11.

On the other hand, the compressor 2, the outdoor expansion valve 6, the indoor expansion valve 8, and the solenoid valves 21 and 22 are connected to the output of the heat pump ECU11. The heat pump ECU11 controls the outputs of the respective sensors, the setting input from the air conditioner operation unit 75, and the information from the vehicle controller 90.

[ concerning heating mode ]

In the air conditioner 100 for a vehicle thus configured, a plurality of heating modes can be selectively executed for the heating operation by the heat pump ECU11. In the present embodiment, a plurality of heating modes including an outside air endothermic heating mode and a hot air heating mode can be selectively executed. The heating modes will be described below.

(1) External air heat absorption heating mode (usual heating mode)

Fig. 3 shows the flow of the refrigerant circuit R in the outside air endothermic heating mode (solid arrows). When the heat pump ECU11 executes the external air heat absorption heating mode, the outdoor expansion valve 6 is opened, and the electromagnetic valve 21 and the indoor expansion valve 8 are fully closed.

The compressor 2 and the blower 27 are operated, and the air mixing damper 28 adjusts the ratio of the air blown from the blower 27 to the indoor heat exchanger 4. Thereby, the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4. In the indoor heat exchanger 4, the air in the air flow passage 3 exchanges heat with the high-temperature and high-pressure refrigerant, that is, the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out into the vehicle interior from the air outlet 29, thereby heating the vehicle interior.

On the other hand, the refrigerant in the indoor heat exchanger 4 is cooled by the heat extracted by the air, and condensed and liquefied. After the liquefied refrigerant exits the indoor heat exchanger 4, it reaches the outdoor expansion valve 6 through the refrigerant pipes 13G and 13H. After the outdoor expansion valve 6 is depressurized, the refrigerant flows into the outdoor heat exchanger 7. The refrigerant flowing into the outdoor heat exchanger 7 evaporates, and heat is extracted (absorbed) from outside air flowing in by running of the vehicle or outside air ventilated by an outdoor blower (not shown). That is, the refrigerant circuit R functions as a heat pump.

Then, the following cycle is repeated: the low-temperature refrigerant from the outdoor heat exchanger 7 flows into the accumulator 12 through the refrigerant pipe 13A and the check valve 20, and after the accumulator 12 performs gas-liquid separation, the gas refrigerant is sucked into the compressor 2 through the refrigerant pipe 13E.

(2) Hot air heating mode

Fig. 4 shows the flow of refrigerant (solid arrows) of the refrigerant circuit R in the hot-gas heating mode. When the heat pump ECU11 executes the hot air heating mode, the solenoid valve 22 is opened, and the solenoid valve 21 and the indoor expansion valve 8 are fully closed.

The compressor 2 and the blower 27 are operated, and the air mixing damper 28 adjusts the ratio of the air blown from the blower 27 to the indoor heat exchanger 4. In the indoor heat exchanger 4, the air in the air flow passage 3 exchanges heat with the high-temperature and high-pressure refrigerant, that is, the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out into the vehicle interior from the air outlet 29, thereby heating the vehicle interior.

On the other hand, the refrigerant in the indoor heat exchanger 4 is cooled and condensed by taking heat from the air. The following cycle was repeated: the condensed refrigerant flows out of the indoor heat exchanger 4, flows into the accumulator 12 through the refrigerant pipes 13G, 13B, and 13A, and is gas-liquid separated in the accumulator 12, and then the gas refrigerant is sucked into the compressor 2 through the refrigerant pipe 13E. In this way, in the hot gas heating mode, the following cycle is adopted: the refrigerant is compressed by the compressor without absorbing heat from the outside air in the outdoor heat exchanger 7, and is high-temperature and high-pressure refrigerant, and exchanges heat with the air passing through the indoor heat exchanger 4. Therefore, the hot air heating mode is hardly affected by the outside air temperature, and the heating operation can be performed even in an extremely low-temperature environment.

[ selection of heating mode ]

In general, an air conditioner for a vehicle performs an external air heat absorption heating mode to heat a vehicle interior. As described above, in the outdoor air heat absorption and heating mode, the refrigerant evaporates in the outdoor heat exchanger 7 to absorb heat from the outside air, but in a case where the outside air temperature is extremely low, or the like, the refrigerant may not absorb heat from the outside air. In such a case, in the heating operation by the outside air heat absorption heating mode, the desired heating operation cannot be performed, and it is necessary to drive the auxiliary heater or the like to supplement the heating. On the other hand, in the hot-air heating mode, the refrigerant does not exchange heat with the outside air in the outdoor heat exchanger 7, and therefore, the refrigerant is less affected by the outside air temperature, and the heating operation can be performed even in an extremely low-temperature environment, and the auxiliary heater is not necessarily required to supplement the heating operation.

Therefore, in the vehicle air conditioner 100 according to the present embodiment, as described above, a plurality of heating modes including the outside air heat absorption heating mode and the hot air heating mode can be selectively executed. The heat pump ECU11 selects an appropriate heating mode from the plurality of heating modes according to predetermined conditions and executes the selected heating mode. The hot air heating selection condition for selecting the hot air heating mode is set in advance for the heat pump ECU11 as one condition for selecting the optimum heating mode according to the running environment of the vehicle.

The hot gas heating selection condition can be set, for example, based on the pressure value of the refrigerant in the compressor 2, that is, as a threshold value for the pressure value. In this case, the heat pump ECU11 selects the hot air heating mode when the pressure value satisfies the hot air heating selection condition, and selects the outside air endothermic heating mode when the pressure value does not satisfy the hot air heating selection condition.

That is, the heat pump ECU11 selects and executes the hot air heating mode by appropriately selecting and executing the heating mode in accordance with the hot air heating selection condition, for example, in a case where the external air endothermic heating mode cannot achieve desired heating, such as in a case where the external air temperature is extremely low. By doing so, it is possible to achieve desired heating according to the running environment of the vehicle without driving the auxiliary heater. In the present embodiment, a threshold value Pth (for example, 0.07 MPaG) for the initial pressure value before the start of the compressor 2 is determined as the hot gas heating selection condition. Here, as the initial pressure value before the start of the compressor 2, a pressure value of the refrigerant before the start command is input to the compressor 2 (excluding the instant of input) and in a state where the compressor 2 is not operated is used.

In the present embodiment, the heat pump ECU11 selects and executes the heating mode as follows based on the threshold value Pth for the initial pressure value of the compressor 2 determined as the hot gas heating selection condition. The selection of the heating mode by the heat pump ECU11 will be described below with reference to the flowchart of fig. 5.

As shown in fig. 5, when the heating operation is selected by the automatic mode or the manual operation (manual mode) of the air conditioner operation unit 75, the heat pump ECU11 sets a heating request (step S101) and obtains an initial pressure value, which is a pressure value before the start of the compressor 2, for selecting the heating mode (step S102). The heat pump ECU11 compares the initial pressure value with a threshold Pth for the initial pressure value (step S102). In step S102, when the initial pressure value is equal to or lower than the threshold value Pth, the hot air heating mode is selected (step S103), and when the initial pressure value is higher than the threshold value Pth, the outside air heat absorption heating mode is selected (step S104).

As described above, according to the present embodiment, as the hot gas heating selection condition, the threshold value Pth for the initial pressure value of the compressor 2 is determined in advance, and whether or not to select the hot gas heating mode is determined based on the threshold value Pth. Here, the initial pressure of the compressor 2 represents a value reflecting the condition of the vehicle including the outside air temperature. Therefore, as the hot air heating selection condition, the threshold value Pth for the initial pressure value is determined, whereby the hot air heating mode can be selected and executed according to the condition of the vehicle. That is, the necessary heating capacity can be ensured without using an auxiliary heater.

(second embodiment)

Fig. 6 shows a schematic configuration of a vehicle air conditioner 200 according to a second embodiment of the present invention. As shown in fig. 6, the vehicle air conditioner 200 of the present embodiment differs from the vehicle air conditioner 100 of the first embodiment in that the refrigerant pipe 13I branching from the refrigerant pipe 13A is provided on the refrigerant inlet side of the accumulator 12 of the refrigerant pipe 13A.

That is, one end of the refrigerant pipe 13I is connected to the refrigerant pipe 13A on the refrigerant inlet side of the accumulator 12, and the other end of the refrigerant pipe 13I is connected to the refrigerant discharge side of the compressor 2 of the refrigerant pipe 13F. In this way, the refrigerant pipe 13I forms a discharge bypass circuit that bypasses the outlet side and the inlet side of the compressor 2. The connection portion between one end of the refrigerant pipe 13I and the refrigerant pipe 13A is not limited to the refrigerant inlet side of the accumulator 12, and may be located upstream of the compressor sensor 72.

The refrigerant pipe 13I is provided with a solenoid valve 24 for controlling inflow of the refrigerant into the refrigerant pipe 13I. By opening the electromagnetic valve 24, the high-temperature and high-pressure refrigerant compressed in the compressor 2 is discharged to the refrigerant pipe 13F, and a part of the high-temperature and high-pressure refrigerant having passed through the refrigerant pipe 13F flows into the refrigerant pipe 13I. The high-temperature and high-pressure refrigerant flowing into the refrigerant pipe 13I is again sucked into the compressor 2 through the accumulator 12.

In the vehicle air conditioner 200 of the present embodiment, as shown in fig. 7, the solenoid valve 24 is also connected to the output of the heat pump ECU11, and the solenoid valve 24 is also controlled by the heat pump ECU11 based on the output of each sensor, the setting input from the air conditioner operation unit 75, and the information from the vehicle controller 90.

[ concerning heating mode ]

In the air conditioner 200 for a vehicle thus configured, a plurality of heating modes including the external air heat absorption heating mode and the two hot air heating modes, i.e., the first hot air heating mode and the second hot air heating mode, can be selectively executed for the heating operation by the heat pump ECU11. Hereinafter, the first hot air heating mode and the second hot air heating mode will be described.

(1) First hot air heating mode

Fig. 8 shows the flow of the refrigerant circuit R of the first hot gas heating mode (solid arrows). The first hot-gas heating mode is a hot-gas heating mode in which the refrigerant is not circulated to the refrigerant pipe 13I, that is, the bypass circuit is not used, and the flow of the refrigerant in the refrigerant circuit R is the same as that in the hot-gas heating mode of the first embodiment (see fig. 4).

As shown in fig. 8, in the first hot air heating mode, when the heat pump ECU11 performs the hot air heating mode, the solenoid valve 22 is opened, and the solenoid valves 21 and 24 and the indoor expansion valve 8 are fully closed.

The compressor 2 and the blower 27 are operated, and the air mixing damper 28 adjusts the ratio of the air blown from the blower 27 to the indoor heat exchanger 4. In the indoor heat exchanger 4, the air in the air flow passage 3 exchanges heat with the high-temperature and high-pressure refrigerant, that is, the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out into the vehicle interior from the air outlet 29, thereby heating the vehicle interior.

On the other hand, the refrigerant in the indoor heat exchanger 4 is cooled and condensed by taking heat from the air. The following cycle was repeated: after exiting the indoor heat exchanger 4, the condensed refrigerant flows into the accumulator 12 through the refrigerant pipes 13G, 13B, and 13A, and after the accumulator 12 performs gas-liquid separation, the gas refrigerant is sucked into the compressor 2 through the refrigerant pipe 13E.

(2) Second hot air heating mode

Fig. 9 shows the flow of refrigerant (solid arrows) of the refrigerant circuit R of the second hot gas heating mode. The second hot-gas heating mode is a hot-gas heating mode in which the refrigerant flows through the refrigerant pipe 13I and the discharge bypass circuit is used.

As shown in fig. 9, in the second hot air heating mode, when the heat pump ECU11 performs the hot air heating mode, the solenoid valves 22 and 24 are opened, and the solenoid valve 21 and the indoor expansion valve 8 are fully closed.

The compressor 2 and the blower 27 are operated, and the air mixing damper 28 adjusts the ratio of the air blown from the blower 27 to the indoor heat exchanger 4. A part of the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4 through the refrigerant pipe 13F, and the remaining part of the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the accumulator 12 through the refrigerant pipe 13I (discharge bypass circuit).

The high-temperature and high-pressure refrigerant flowing into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 3, and thereby the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out into the vehicle interior from the air outlet 29, thereby heating the vehicle interior. The refrigerant subjected to heat exchange in the indoor heat exchanger 4 is cooled and condensed by taking heat from the air. After exiting the indoor heat exchanger 4, the condensed refrigerant flows into the accumulator 12 through the refrigerant pipes 13G, 13B, and 13A.

On the other hand, the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the accumulator 12 again through the refrigerant pipe 13I. That is, the refrigerant liquefied in the indoor heat exchanger 4 and the refrigerant compressed by the compressor 2 at high temperature and high pressure flow into the accumulator 12. The following cycle was repeated: the refrigerant flowing into the accumulator 12 is gas-liquid separated, and then is sucked into the compressor 2 as a gas refrigerant through the refrigerant pipe 13E.

[ selection of heating mode ]

In the vehicle air conditioner 200 of the present embodiment, as described above, a plurality of heating modes including the outside air heat absorbing heating mode, the first hot air heating mode, and the second hot air heating mode can be selectively executed. The heat pump ECU11 selects and executes an appropriate heating mode from a plurality of heating modes according to predetermined conditions. The hot air heating selection condition for selecting the hot air heating mode is determined in advance for the heat pump ECU11 as one condition for selecting the optimum heating mode according to the running environment of the vehicle.

Since the vehicle air conditioner 200 can execute the first hot air heating mode and the second hot air heating mode, a first threshold value Pth1 (for example, 0.07 MPaG) for an initial pressure value before the start of the compressor 2 and a second threshold value Pth2 (for example, 0.05 MPaG) indicating a value lower than the first threshold value are determined as hot air heating selection conditions.

The heat pump ECU11 selects and executes the heating mode in accordance with the first threshold value Pth1 and the second threshold value Pth2 for the initial pressure value of the compressor 2, which are determined as the hot gas heating selection conditions, as follows. The selection of the heating mode by the heat pump ECU11 will be described below with reference to the flowchart of fig. 10.

As shown in fig. 10, when the heating operation is selected automatically or by a manual operation with respect to the air conditioner operation unit 75, the heat pump ECU11 sets a heating request (step S201) and obtains an initial pressure value, which is a pressure value before the start of the compressor 2, for selecting the heating mode (step S202). The heat pump ECU11 compares the initial pressure value with a first threshold Pth1 for the initial pressure value set in advance (step S202).

In step S202, the heat pump ECU11 selects the outside air heat absorption heating mode when the initial pressure value is greater than the first threshold Pth1 (step S203). In step S202, when the initial pressure value is equal to or less than the first threshold value Pth1, the routine proceeds to step S204, where the initial pressure value is compared with the second threshold value Pth2 (step S204). In step S204, the heat pump ECU11 selects the first hot gas heating mode if the initial pressure value is greater than the second threshold Pth2 (step S205). In step S204, if the initial pressure value is equal to or less than the second threshold Pth 2. A second hot gas heating mode is selected (step S206).

As described above, according to the present embodiment, it is possible to selectively perform two hot gas heating modes, i.e., the first hot gas heating mode using no exhaust bypass circuit and the second hot gas heating mode using the exhaust bypass circuit. As hot gas heating selection conditions, a first threshold value Pth1 and a second threshold value Pth2 for the initial pressure value of the compressor 2 are determined in advance, and whether to select the first hot gas heating mode or the second hot gas heating mode is determined based on the first threshold value Pth1 and the second threshold value Pth 2.

Here, the second hot gas heating mode returns the refrigerant compressed by the compressor 2 to be at a high temperature and a high pressure to the compressor 2 through the discharge bypass circuit, and thus the power of the compressor 2 can be increased. Therefore, the second hot air heating mode can supply air at a desired temperature into the vehicle interior earlier than the first hot air heating mode.

Since the initial pressure of the compressor 2 indicates a value reflecting the condition of the vehicle including the outside air temperature, the first threshold value Pth1 for the initial pressure value and the second threshold value Pth2 indicating a value lower than the first threshold value Pth1 are determined as hot air heating selection conditions, and either one of the first hot air heating mode and the second hot air heating mode can be selected and executed optimally according to the condition of the vehicle. That is, a more appropriate heating mode can be selected and executed, and necessary heating capacity can be ensured without using an auxiliary heater.

(modification)

As described above, in the outside air heat absorption heating mode, the refrigerant is circulated to the outdoor heat exchanger 7, and heat exchange between the refrigerant and the outside air is performed in the outdoor heat exchanger 7. At this time, the refrigerant evaporates in the outdoor heat exchanger 7, and the outdoor heat exchanger 7 is at a low temperature, so that moisture in the outside air may become frost and adhere to the surface of the outdoor heat exchanger 7. If frosting occurs in the outdoor heat exchanger 7, the refrigerant in the outdoor heat exchanger 7 cannot absorb heat from the outside air, and the outside air cannot absorb heat to generate heat.

Therefore, in the case where there is frost in the outdoor heat exchanger 7, it is sometimes preferable to select and execute the hot gas heating mode. Therefore, the heat pump ECU11 can set the hot gas selection condition according to the presence or absence of frosting of the outdoor heat exchanger 7. For example, in addition to the first threshold value Pth1 and the second threshold value Pth2 for the initial pressure value described above, detection of frosting of the outdoor heat exchanger 7 is determined as the hot gas heating selection condition.

When such hot air heating selection conditions are set, the heat pump ECU11 selects and executes a heating mode from a plurality of heating modes including an outside air endothermic heating mode, a first hot air heating mode, and a second hot air heating mode according to the flowchart shown in fig. 11.

As shown in fig. 11, when the heating operation is selected automatically or by a manual operation with respect to the air conditioner operation unit 75, the heat pump ECU11 sets a heating request (step S301), obtains an initial pressure value of the compressor 2 for selecting the heating mode, and compares the initial pressure value with a first threshold value Pth1 (step S302).

When the initial pressure value is greater than the first threshold value Pth1 as a result of the comparison of the initial pressure value and the first threshold value Pth1 in step S302, the heat pump ECU11 determines whether or not frosting of the outdoor heat exchanger 7 is present (step S303). In the determination in step S303, when it is determined that the outdoor heat exchanger 7 is not frosted, the external air heat absorption heating mode is selected (step S305), and when the outdoor heat exchanger 7 is frosted, the first hot air heating mode is selected (step S306).

When the initial pressure value is equal to or lower than the first threshold value Pth1 as a result of the comparison of the initial pressure value and the first threshold value Pth1 in step S302, the heat pump ECU11 compares the initial pressure value with the second threshold value Pth2 (step S304). In step S304, the heat pump ECU11 selects the first hot gas heating mode if the initial pressure value is greater than the second threshold Pth2 (step S306). In step S304, when the initial pressure value is equal to or lower than the second threshold Pth2, the second hot gas heating mode is selected (step S307).

In the present modification, by including the presence or absence of frosting to the outdoor heat exchanger 7 in the hot gas heating selection condition, a more preferable heating mode can be selected and executed according to the condition of the vehicle.

The detection of the frost formation may be performed, for example, by subtracting a differential value obtained by subtracting the surface temperature of the outdoor heat exchanger 7 detected by the outdoor heat exchanger sensor 74 from the outside air temperature Tam detected by the outside air temperature sensor 71. That is, when the difference value is a value greater than a predetermined temperature, frosting is detected. The heat pump ECU11 may set a hot-air heating selection condition for immediately selecting the hot-air heating mode when, for example, frosting of the outdoor heat exchanger 7 is detected.

(third embodiment)

In the second embodiment and the modification thereof, the selection of the heating mode in the case where the heating request is made is described in the vehicular air conditioning apparatus 200, but it is also possible to consider the case where frosting occurs during the running of the vehicle. Therefore, in this embodiment, selection or switching of a heating mode based on the result of determining the presence or absence of frosting during execution of an arbitrary heating mode will be described with reference to the flowchart of fig. 12.

As shown in fig. 12, the heat pump ECU11 determines whether or not the heating operation is in the heating operation (step S401), in particular, whether or not the heating operation is in the heating mode by the external air heat absorption (step S402). If it is determined in step S402 that the heating mode in operation is not the external air heat absorption heating mode, the heating mode in operation is maintained, and the execution of the heating mode in operation is continued (step S404). In the judgment in step S402, when it is judged that the heating mode in operation is the outside air heat absorption heating mode, the presence or absence of frosting on the outdoor heat exchanger 7 is judged (step S403).

As a result of the determination in step S403, the heat pump ECU11 determines that the outdoor heat exchanger 7 is not frosted, and maintains the heating mode during operation, and continues the execution of the heating mode during operation (step S404). When it is determined that the outdoor heat exchanger 7 is frosted as a result of the determination in step S403, the heat pump ECU11 acquires the outside air temperature Tam detected by the outside air temperature sensor 71, and compares the outside air temperature Tam with a predetermined threshold temperature Tth for the outside air temperature (step S405).

As a result of the comparison between the outside air temperature Tam and the threshold temperature Tth in step S405, the heat pump ECU11 selects the first hot air heating mode (S406) and switches the heat absorption heating mode from the outside air to the first hot air heating mode to perform the heating operation when the outside air temperature Tam is greater than the threshold temperature Tth.

When the outside air temperature Tam is equal to or lower than the threshold temperature Tth as a result of the comparison between the outside air temperature Tam and the threshold temperature Tth in step S405, the heat pump ECU11 selects the second hot air heating mode (S407), and switches the heating operation from the outside air heat absorption heating mode to the second hot air heating mode.

When frosting occurs during running of the vehicle and the heating capacity cannot be ensured by the outside air heat absorption heating mode, the first hot air heating mode or the second hot air heating mode can be selected according to the condition of the vehicle, and the operation can be performed by switching from the outside air heat absorption heating mode. Therefore, the necessary heating capacity can be ensured without using an auxiliary heater or the like according to the condition of the vehicle.

In the above-described embodiments, the external air heat absorption heating mode using the outdoor heat exchanger as the heat exchanger for heat absorption has been described as an example of the heating modes other than the hot air heating mode among the plurality of heating modes. For example, a waste heat recovery heating mode may be included in which waste heat of a battery, a motor, or the like is recovered using a refrigerant-heat medium heat exchanger, and the refrigerant absorbs heat through a heat medium to be used.

As described above, according to the vehicle air conditioning apparatuses 100 and 200 and the modifications thereof of the above-described embodiments, the heat pump ECU11 can execute a plurality of heating modes including the hot air heating mode (the first hot air heating mode, the second hot air heating mode) and the outside air heat absorption heating mode. In addition, although the hot air heating mode, which is hardly affected by the outside air temperature and which can realize heating without the need for supplementary heating by an auxiliary heater or the like, is performed in accordance with the hot air heating selection condition determined in advance, the hot air endothermic heating mode is performed without the need for the hot air heating mode. Thus, even if the supplementary heating by the auxiliary heater or the like is not performed, an appropriate heating mode can be selected and executed according to the condition of the vehicle, and sufficient heating capacity can be ensured.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to the embodiments, and the present invention is also included in the present invention even if the configuration is modified within the scope of the present invention.

Reference numerals illustrate:

100. 200: an air conditioning device for a vehicle; 2: a compressor; 3: an air circulation channel; 4: an indoor heat exchanger; 6: an outdoor expansion valve; 7: an outdoor heat exchanger; 8: an indoor expansion valve; 9: a heat absorber; 10: a HAVC unit; 11: a heat pump ECU (control device); 12: a reservoir; 21. 22, 24: an electromagnetic valve; 72: a compressor sensor.

Claims (9)

1. An air conditioner for a vehicle, characterized in that,

the air conditioner for a vehicle includes:

a refrigerant circuit comprising: a compressor for compressing a refrigerant; an indoor heat exchanger for exchanging heat between heat of the refrigerant compressed by the compressor and air supplied into the vehicle interior; and a heat exchanger for absorbing heat, wherein the heat exchanger exchanges heat between the refrigerant and outside air or other heat medium; and

a control device for controlling the refrigerant circuit,

the refrigerant circuit having a hot gas circuit bypassing the heat exchanger to flow refrigerant from a downstream side of the indoor heat exchanger to a suction side of the compressor,

the control device is capable of selectively executing a plurality of heating modes including a hot-air heating mode that circulates a refrigerant in the hot-air circuit, heats the interior of the vehicle by heat of the refrigerant compressed by the compressor without heat exchange between the refrigerant and outside air or other heat medium in the heat exchanger,

the control device sets hot air heating selection conditions for selecting the hot air heating mode.

2. The vehicular air conditioner according to claim 1, wherein,

the hot gas heating selection condition is set according to a threshold value for an initial pressure value of the refrigerant sucked into the compressor before the start-up of the compressor,

the hot gas heating mode is selected in case the initial pressure value is lower than the threshold value.

3. The vehicular air conditioner according to claim 1 or 2, characterized in that,

the refrigerant circuit has a discharge bypass circuit connecting a discharge side of the compressor with a suction side so that the refrigerant discharged from the compressor is sucked into the compressor again,

the hot gas heating mode includes a first hot gas heating mode that does not use the exhaust bypass loop and a second hot gas heating mode that uses the exhaust bypass loop.

4. The air conditioner for a vehicle according to claim 3, wherein,

as the hot gas heating selection condition, a first threshold value for an initial pressure value of the refrigerant sucked into the compressor before the start of the compressor and a second threshold value representing a value lower than the first threshold value are set,

selecting the first hot gas heating mode if the initial pressure value is greater than the second threshold value and is below the first threshold value,

and selecting the second hot gas heating mode when the initial pressure value is below the second threshold value.

5. The air conditioner for a vehicle according to claim 3, wherein,

as the hot gas heating selection condition, a first threshold value for an initial pressure value of the refrigerant sucked into the compressor before the start of the compressor, a second threshold value indicating a value lower than the first threshold value, and the presence or absence of frost formation in the outdoor heat exchanger are set,

selecting the first hot gas heating mode in a case where the initial pressure value is greater than the second threshold value and is less than the first threshold value and in a case where the initial pressure value is greater than the first threshold value and frosting to the outdoor heat exchanger is detected,

and selecting the second hot gas heating mode when the initial pressure value is less than or equal to the second threshold value.

6. The vehicular air-conditioning apparatus according to any one of claims 3 to 5, characterized in that,

the connection portion of the discharge bypass circuit on the refrigerant suction side of the compressor is provided on the refrigerant upstream side of a pressure sensor that detects the pressure value of the refrigerant sucked into the compressor.

7. The vehicular air-conditioning apparatus according to any one of claims 3 to 6, characterized in that,

the connection portion of the discharge bypass circuit on the refrigerant suction side of the compressor is provided on the refrigerant upstream side of an accumulator disposed on the refrigerant upstream side of the compressor.

8. The vehicular air-conditioning apparatus according to any one of claims 1 to 7, characterized in that,

the plurality of heating modes include an outside air heat absorption heating mode in which heat exchange between the refrigerant and outside air is performed in the outdoor heat exchanger,

the control device selects and executes an external air endothermic heating mode without selecting the hot air heating mode.

9. The vehicular air-conditioning apparatus according to claim 8, characterized in that,

the control device switches to the hot air heating mode according to an outside air temperature when frost formation to the outdoor heat exchanger is detected during the operation of the outside air heat absorption heating mode.