Hybrid electric vehicle

Abstract

The invention provides a hybrid electric vehicle. The hybrid electric vehicle is capable of traveling in an HEV mode and a BEV mode, and is characterized by being provided with: a radiator; an air-conditioning device that includes a condenser and a pressure sensor and that performs air conditioning in the vehicle interior; a cooling fan that operates in accordance with rotation of the engine and blows cooling air to the radiator and the condenser; and a control unit that controls the operation of the engine and the air-conditioning device, and that reduces the amount of heat dissipated by the condenser when the cooler high pressure detected by the pressure sensor is equal to or greater than a first pressure during travel in the BEV mode.

Description

Technical Field

[0001] The invention relates to control of an air conditioning device of a hybrid electric vehicle. Background Art

[0002] Vehicles are being used that use a cooling fan driven by an engine to dissipate heat from a condenser in a refrigeration cycle. In such a vehicle, if the engine speed is low, the amount of air supplied to the condenser is reduced, which may cause the pressure in the refrigeration cycle to rise and cause the air conditioning device to stop. Therefore, a vehicle is proposed that is configured in such a way that, in addition to the engine-driven cooling fan, an electric auxiliary fan is provided, and when the engine speed is low, the air volume of the auxiliary fan is increased to obtain sufficient heat dissipation from the condenser (for example, refer to Japanese Patent Laid-Open No. 10-157451). Summary of the invention

[0003] However, in recent years, hybrid electric vehicles that can travel in an HEV mode using an engine and a vehicle drive motor and a BEV mode using an electric motor with the engine stopped have been used. Such hybrid electric vehicles are provided with an electric cooling fan so that sufficient heat can be dissipated from the condenser even when traveling in the BEV mode.

[0004] On the other hand, among hybrid electric vehicles such as those described above, there are vehicles equipped with an engine-driven cooling fan in order to ensure the heat dissipation of the radiator for cooling the engine cooling water when going uphill or towing. In such a vehicle, when driving in the BEV mode with the engine stopped, the ventilation volume of the condenser may be reduced, and the heat dissipation of the condenser may not be sufficient, causing the pressure in the refrigeration cycle to rise, and thus making it impossible to continue BEV driving.

[0005] Therefore, an object of the present disclosure is to reduce the amount of heat dissipated by a condenser during BEV running in a hybrid electric vehicle equipped with an engine-driven cooling fan, thereby continuing the BEV running.

[0006] The hybrid electric vehicle disclosed in the present invention is capable of traveling in an HEV mode in which the vehicle is driven by an engine and an electric motor and in a BEV mode in which the engine is stopped and the vehicle is driven by the electric motor, and is characterized in that it comprises: a radiator for cooling cooling water circulating inside the engine; an air-conditioning device, which includes a compressor, a condenser for condensing the refrigerant compressed by the compressor, and a pressure sensor for detecting the pressure of the refrigerant compressed by the compressor, and performs air conditioning in a vehicle cabin; a cooling fan that operates in response to the rotation of the engine and blows cooling air to the radiator and the condenser; and a control unit that controls the operation of the engine and the air-conditioning unit, and when the pressure of the refrigerant detected by the pressure sensor is above a predetermined first pressure during traveling in the BEV mode, the control unit reduces the amount of heat dissipated by the condenser.

[0007] Since the amount of heat dissipated by the condenser is reduced during BEV traveling, it is possible to suppress a pressure increase of the refrigerant during BEV traveling and continue BEV traveling.

[0008] In the hybrid electric vehicle disclosed in the present invention, it can also be set as follows: when the pressure of the refrigerant detected by the pressure sensor is higher than the first pressure and the ambient temperature is lower than a predetermined first temperature during driving in the BEV mode, the control unit maintains the driving mode at the BEV mode and reduces the heat dissipation of the condenser; when the pressure of the refrigerant detected by the pressure sensor is higher than the first pressure and the ambient temperature is higher than the first temperature during driving in the BEV mode, the control unit starts the engine and switches the driving mode from the BEV mode to the HEV mode, and does not reduce the heat dissipation of the condenser.

[0009] This allows the BEV to continue traveling while suppressing a pressure increase in the refrigerant during traveling. Furthermore, when the ambient temperature is high and cooling is required, sufficient cooling can be performed by increasing the amount of heat dissipated by the condenser.

[0010] In the hybrid electric vehicle disclosed in the present invention, it can also be set that the air-conditioning device includes an in-cabin fan and a switching damper, the in-cabin fan blows air into the cabin, the switching damper switches between external air introduction for introducing external air into the cabin and internal air circulation for circulating the air in the cabin, and the control unit reduces the heat dissipation of the condenser by switching the switching damper to the internal air circulation and increasing the duty cycle of the in-cabin fan.

[0011] In this way, the heat dissipation of the condenser is reduced by improving the efficiency of the refrigeration cycle, so that the heat dissipation of the condenser can be reduced without impairing the comfort of the passengers.

[0012] In the hybrid electric vehicle disclosed in the present invention, the air-conditioning device can also be configured to include an evaporator in which refrigerant circulates to cool the air to be blown into the vehicle cabin, and the control unit increases the set value of the refrigerant temperature at the evaporator outlet and decreases the upper limit speed of the compressor as the pressure of the refrigerant detected by the pressure sensor increases, thereby reducing the heat dissipation of the condenser.

[0013] In this way, by reducing the cooling load of the air-conditioning device, it is possible to reduce the amount of heat dissipated by the condenser and continue the BEV travel.

[0014] In the hybrid electric vehicle disclosed in the present invention, it can also be set that when the pressure of the refrigerant detected by the pressure sensor is above a second pressure that is higher than the first pressure and lower than the engine starting pressure, the control unit reduces the duty cycle of the fan in the vehicle cabin as the refrigerant temperature at the evaporator outlet increases, thereby reducing the heat dissipation of the condenser.

[0015] When the refrigerant pressure is still higher than the second pressure even though the efficiency of the refrigeration cycle is improved and the load of the air conditioning device is reduced, the load of the air conditioning device is further reduced by reducing the duty cycle of the fan in the vehicle cabin. Therefore, the increase in the refrigerant pressure can be more effectively suppressed and the vehicle can continue to travel in the BEV mode.

[0016] According to the present disclosure, in a hybrid electric vehicle provided with a cooling fan driven by an engine, it is possible to reduce the amount of heat dissipated by a condenser during BEV running and continue the BEV running. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like symbols represent like elements, and wherein:

[0018] Figure 1 A system diagram showing the structure of a hybrid electric vehicle according to an embodiment;

[0019] Figure 2 To express Figure 1 A map showing the relationship between the set value of the refrigerant temperature at the evaporator outlet and the cooler high pressure stored in the memory of the control unit of the hybrid electric vehicle shown;

[0020] Figure 3 To express Figure 1A map showing the relationship between the compressor upper limit rotation speed and the cooler high pressure stored in the memory of the control unit of the hybrid electric vehicle shown;

[0021] Figure 4 To express Figure 1 A map showing the relationship between the air volume of the fan in the vehicle cabin and the refrigerant temperature at the evaporator outlet, stored in a memory of a control unit of the hybrid electric vehicle shown;

[0022] Figure 5 To express Figure 1 A flowchart of the operation of the hybrid electric vehicle shown;

[0023] Figure 6 To express Figure 5 Flow chart of the condenser heat dissipation reduction process shown. DETAILED DESCRIPTION

[0024] The hybrid electric vehicle 100 of the embodiment will be described below with reference to the drawings. The hybrid electric vehicle 100 can travel in an HEV (Hybrid Electric Vehicle) mode in which the engine 11 and the motor 61 for driving the vehicle are used to travel, and in a BEV (Bonus Electric Vehicle) mode in which the engine 11 is stopped and the motor 61 is used to travel.

[0025] like Figure 1 As shown, the hybrid electric vehicle 100 includes an engine cooling circuit 30, a refrigeration cycle circuit 50, a motor cooling circuit 70, a control unit 80, and an ambient temperature sensor 57. The engine cooling circuit 30 is a circuit that circulates cooling water in the engine 11 to cool the engine 11. The refrigeration cycle circuit 50 is a circuit that compresses and expands the refrigerant and cools the vehicle cabin. The motor cooling circuit 70 is a circuit that circulates the coolant in the motor 61 and the PCU 62 to cool the motor 61 and the PCU 62.

[0026] First, the engine cooling circuit 30 is described. In the engine cooling circuit 30, the engine 11, the three-way flow control valve 20, the heater core 13, the electric pump 14, the water heater 15, the thermostat 18 and the radiator 16 are arranged in series in order from the upstream side. The engine cooling circuit 30 is a flow path for cooling water to flow through the above-mentioned devices.

[0027] The engine 11 is a driving source of the hybrid electric vehicle 100. A cooling water flow path 11a through which cooling water flows is provided in the engine 11. In addition, an engine driven pump 12 driven by the engine 11 is installed on the engine 11. The engine driven pump 12 works in conjunction with the engine 11. The discharge port of the engine driven pump 12 is connected to the inlet of the cooling water flow path 11a. The three-way flow regulating valve 20 is provided between the engine 11 and the heater blower 13 of the engine cooling circuit 30. The three-way flow regulating valve 20 has three ports, namely a first port 21, a second port 22 and a third port 23. The three-way flow regulating valve 20 can switch the flow path of the cooling water by opening and closing the three ports respectively.

[0028] The heater core 13 is a heat exchanger that has a cooling water flow passage 13a inside for circulating the cooling water having a relatively high temperature that has passed through the cooling water flow passage 11a of the engine 11, and heats the air to be blown into the vehicle compartment. The heater core 13 is disposed in a blowout duct 47 that blows air into the vehicle compartment. A flow passage switching damper 19 is provided upstream of the heater core 13 in the blowout duct 47, and the flow passage switching damper 19 switches between shutting off and opening the flow of air to the heater core 13.

[0029] The electric pump 14 is driven by an electric motor (not shown) and circulates cooling water in the engine cooling circuit 30. The water heater 15 is a heater for heating cooling water to the heater core 13 when the hybrid electric vehicle 100 is running in the BEV mode. In other words, the water heater 15 is a heat source for heating the cabin when the hybrid electric vehicle 100 is running in the BEV mode. The water heater 15 has a cooling water flow channel 15a inside for cooling water to flow.

[0030] The thermostat 18 is a switching valve that switches the flow of the cooling water to the radiator bypass pipe 38 when the temperature of the cooling water is low, and switches the flow path so that the cooling water flows to the radiator 16 when the temperature of the cooling water is high.

[0031] The radiator 16 is a heat exchanger that uses external air to cool cooling water. The radiator 16 has a cooling water flow channel 16a inside for cooling water to flow. The radiator 16 is mounted on a radiator bracket 25 provided in a front compartment in front of the vehicle. The radiator bracket 25 forms an air guide channel that covers the radiator 16 and introduces external air. A cooling fan 17 is arranged at the rear of the vehicle of the radiator 16, and the cooling fan 17 is operated by the rotation of the engine 11 and blows cooling air to the radiator 16.

[0032] The engine cooling circuit 30 is composed of an engine driven pump 12, a cooling water flow channel 11a of the engine 11, an engine outlet pipe 31, a three-way flow regulating valve 20, a heater bellows inlet pipe 32, a cooling water flow channel 13a of the heater bellows 13, a heater bellows outlet pipe 33, an electric pump 14, a cooling water flow channel 15a of the water heater 15, a water heater outlet pipe 35, an automatic temperature regulator 18, a radiator inlet pipe 36, a cooling water flow channel 16a of the radiator 16, a radiator outlet pipe 37, an engine driven pump inlet pipe 39, a radiator bypass pipe 38 and an engine bypass pipe 34.

[0033] The engine outlet pipe 31 connects the outlet of the cooling water flow channel 11a of the engine 11 and the first port 21 of the three-way flow control valve 20. The heater air box inlet pipe 32 connects the second port 22 of the three-way flow control valve 20 and the inlet of the cooling water flow channel 13a of the heater air box 13. The heater air box outlet pipe 33 connects the outlet of the cooling water flow channel 13a of the heater air box 13 and the suction port of the electric pump 14. The discharge port of the electric pump 14 is connected to the inlet of the cooling water flow channel 15a of the water heater 15. The water heater outlet pipe 35 connects the outlet of the cooling water flow channel 15a of the water heater 15 and the thermostat 18. The radiator inlet pipe 36 connects the thermostat 18 and the inlet of the cooling water flow channel 16a of the radiator 16. The radiator outlet pipe 37 connects the outlet of the cooling water flow channel 16a of the radiator 16 and the engine drive pump inlet pipe 39. The engine driven pump inlet pipe 39 is connected to the suction port of the engine driven pump 12. In addition, the radiator bypass pipe 38 connects the thermostat 18 and the engine driven pump inlet pipe 39 bypassing the radiator 16. The engine bypass pipe 34 connects the water heater outlet pipe 35 of the engine cooling circuit 30 and the third port 23 of the three-way flow control valve 20 in a manner bypassing the engine 11.

[0034] Next, the refrigeration cycle 50 is described. The refrigeration cycle 50 is composed of the compressor 41, the compressor outlet pipe 51, the condenser 42, the condenser outlet pipe 52, the expansion valve 43, the evaporator inlet pipe 53, the evaporator 44, and the evaporator outlet pipe 54.

[0035] The compressor 41 compresses the refrigerant to form a high-temperature, high-pressure gas. The condenser 42 has a refrigerant flow channel 42a inside, and performs heat exchange with the external air flowing outside, so that the high-temperature, high-pressure gas refrigerant compressed by the compressor 41 is cooled and condensed to become a liquid. The discharge port of the compressor 41 and the inlet of the refrigerant flow channel 42a of the condenser 42 are connected through a compressor outlet pipe 51. The condenser 42 is arranged in series with the radiator 16 in the direction of the external air flow upstream of the radiator 16 and is installed on the radiator bracket 25. The cooling fan 17 described above also blows cooling air to the condenser 42.

[0036] The expansion valve 43 is a pressure reducing valve that adiabatically expands the refrigerant that has become a high-pressure liquid in the condenser 42. The expansion valve 43 is connected to an outlet of the refrigerant flow path 42a of the condenser 42 via a condenser outlet pipe 52.

[0037] The evaporator 44 has a refrigerant flow path 44a inside, and cools the air flowing outside by gasifying the refrigerant flowing in the refrigerant flow path 44a. The evaporator 44 is connected to the expansion valve 43 through the evaporator inlet pipe 53. The evaporator 44 is arranged in the blowing duct 47 that blows air into the vehicle cabin, similarly to the heater core 13, and is arranged upstream of the heater core 13. In the blowing duct 47, upstream of the evaporator 44, an in-cabin fan 45 that blows air into the vehicle cabin is arranged. A switching damper 46 is provided upstream of the in-cabin fan 45, and the switching damper 46 switches between external air introduction to introduce external air into the in-cabin fan 45 and internal air circulation to introduce air into the vehicle cabin into the in-cabin fan 45. When the switching damper 46 is for external air introduction, external air is introduced into the in-cabin fan 45, and the external air passes through the evaporator 44 to become cold air and blown into the vehicle cabin. On the other hand, when the damper 46 is switched to internal air circulation, the air in the vehicle cabin is introduced into the vehicle cabin fan 45, and the air in the vehicle cabin is converted into cold air and blown into the vehicle cabin through the evaporator 44. The outlet of the refrigerant flow path 44a of the evaporator 44 is connected to the suction port of the compressor 41 through the evaporator outlet pipe 54.

[0038] The compressor 41, the condenser 42, the expansion valve 43 and the evaporator 44 constitute a refrigeration cycle that compresses and expands the refrigerant and cools the vehicle cabin. The area from the outlet of the compressor 41 to the inlet of the expansion valve 43 is a high-pressure area where the pressure of the refrigerant is relatively high. On the other hand, the area from the outlet of the expansion valve 43 to the suction port of the compressor 41 is a low-pressure area where the pressure of the refrigerant is relatively low. A pressure sensor 55 for detecting the pressure of the refrigerant in the high-pressure area is provided on the compressor outlet pipe 51. The refrigerant pressure detected by the pressure sensor 55 is referred to as "cooler high pressure". In addition, a temperature sensor 56 for detecting the refrigerant temperature at the outlet of the evaporator 44 is provided on the evaporator outlet pipe 54.

[0039] In addition, the compressor 41 , the condenser 42 , the expansion valve 43 , the evaporator 44 , the in-cabin fan 45 , the switching damper 46 , the heater core 13 , the flow path switching damper 19 , the pressure sensor 55 , and the temperature sensor 56 constitute the air conditioning device 200 .

[0040] Next, the motor cooling circuit 70 is described. The motor cooling circuit 70 is composed of the motor 61, the motor outlet pipe 73, the PCU 62, the PCU outlet pipe 74, the coolant pump 63, the coolant pump outlet pipe 71, the HEV radiator 64, and the motor inlet pipe 72.

[0041] The motor 61 is a motor for driving the hybrid electric vehicle 100. The motor 61 has a coolant flow channel 61a for the coolant to flow inside. The PCU 62 converts the DC power supplied from the battery (not shown) into AC power and supplies it to the motor 61, and when the motor 61 functions as a generator, the AC power generated by the motor 61 is converted into DC power to charge the battery. The PCU 62 has a coolant flow channel 62a for the coolant to flow inside. The coolant flow channel 62a of the PCU 62 is connected to the coolant flow channel 61a of the motor 61 through the motor outlet pipe 73. The HEV radiator 64 has a coolant flow channel 64a for the coolant to flow inside, and performs heat exchange with the outside air flowing outside to cool the high-temperature coolant. The HEV radiator 64 is arranged in series with the radiator 16 in the direction of the outside air flow upstream of the radiator 16 and in parallel with the condenser 42, and is installed on the radiator bracket 25. The cooling fan 17 also blows cooling air to the HEV radiator 64. The inlet of the coolant flow channel 64a of the HEV radiator 64 is connected to the discharge port of the coolant pump 63 through the coolant pump outlet pipe 71. In addition, the outlet of the coolant flow channel 64a of the HEV radiator 64 is connected to the coolant flow channel 61a of the motor 61 through the motor inlet pipe 72. The motor cooling circuit 70 circulates the coolant in the motor 61, the PCU 62, and the HEV radiator 64 through the coolant pump 63, and dissipates the heat generated by the motor 61 and the PCU 62 by using the HEV radiator 64, so as to cool the motor 61 and the PCU 62.

[0042] The ambient temperature sensor 57 detects the ambient temperature of the hybrid electric vehicle 100. The ambient temperature sensor 57 may be provided in the vicinity of the external air inlet of the radiator support 25, for example.

[0043] The control unit 80 is a computer having a CPU 81 as a processor for information processing and a memory 82 for storing an operation program, operation data, etc. The engine 11, the three-way flow control valve 20, the electric pump 14, the water heater 15, the compressor 41, the expansion valve 43, the interior fan 45, the switching damper 46, the motor 61, the PCU 62, and the coolant pump 63 are connected to the control unit 80 and operate according to the command of the control unit 80. In addition, the high pressure of the cooler detected by the pressure sensor 55, the refrigerant temperature at the outlet of the evaporator detected by the temperature sensor 56, and the ambient temperature detected by the ambient temperature sensor 57 are input to the control unit 80. The operation of the control unit 80 is realized by the CPU 81 executing the control program stored in the memory 82.

[0044] The memory 82 of the control unit 80 stores Figures 2 to 4The control maps 83 to 85 are shown. Figure 2 As shown in FIG. 8 , the control map 83 is a map that defines the relationship between the set value of the refrigerant temperature at the outlet of the evaporator 44 and the cooler high pressure detected by the pressure sensor 55. Figure 2 In the figure, the first pressure PS1 is a predetermined set pressure for starting the condenser heat dissipation reduction process described later. In addition, the engine starting pressure PE is a set pressure for starting the engine 11 and entering the driving in HEV mode due to the increase of the cooler high pressure. The second pressure PS2 is a pressure that is higher than the first pressure PS1 and slightly lower than the engine starting pressure PE, and is a predetermined set pressure for starting to reduce the air volume of the fan 45 in the vehicle cabin. The control map 83 is a map as follows, that is, when the cooler high pressure becomes higher than the first pressure PS1, the set value of the refrigerant temperature at the outlet of the evaporator 44 is increased from the normal set temperature TS1, and when the cooler high pressure is higher than the second pressure PS2, the set value of the refrigerant temperature at the outlet of the evaporator 44 is set to TS2 which is higher than TS1.

[0045] Figure 3 The control map 84 shown is a map that defines the relationship between the upper limit speed of the compressor 41 and the cooler high pressure. The control map 84 is a map that reduces the upper limit speed of the compressor 41 from the normal upper limit speed R0 when the cooler high pressure becomes higher than the first pressure PS1, and sets the upper limit speed of the compressor 41 to R1 when the cooler high pressure is higher than the second pressure PS2.

[0046] Figure 4 The control map 85 shown is a map that defines the relationship between the air volume of the interior fan 45 and the refrigerant temperature at the outlet of the evaporator 44 detected by the temperature sensor 56. The control map 85 is a map that reduces the air volume of the interior fan 45 from the normally set Q0 when the refrigerant temperature at the outlet of the evaporator 44 is TS1 or higher, and sets the air volume of the interior fan 45 to Q1 when the refrigerant temperature at the outlet of the evaporator 44 is TS3 or higher.

[0047] Next, refer to Figure 5 , the control of the air conditioning device 200 while the hybrid electric vehicle 100 is running in the BEV mode while cooling the cabin through the air conditioning device 200 is described. When the running mode of the hybrid electric vehicle 100 is the BEV mode, since the engine 11 is stopped, the cooling water does not flow in the engine cooling circuit 30, and the cooling fan 17 driven by the engine 11 is stopped. On the other hand, since the motor 61 is driven, the coolant is pumped through the coolant pump 63 as shown in FIG. Figure 1As shown by the arrows in FIG. 1 , the refrigerant circulates through the motor 61, the PCU 62, and the HEV radiator 64 to cool the motor 61 and the PCU 62. In addition, since the vehicle compartment is cooled, the compressor 41 is operated and the refrigerant is Figure 1 The heat circulates as shown by the arrows in FIG. 4 , and is dissipated from the condenser 42 to the outside air.

[0048] The control unit 80 is as follows Figure 5 As shown in step 101 of the embodiment, it is determined whether the hybrid electric vehicle 100 is running in the BEV mode. Figure 5 If the judgment in step 101 is no, then the Figure 5 The process of step 101 is in standby mode.

[0049] If the control unit 80 Figure 5 If the judgment is yes in step 101, then enter Figure 5 In step 102, the control unit 80 determines whether the high pressure of the cooler detected by the pressure sensor 55 is greater than the first pressure PS1. Figure 5 If the judgment is no in step 102, then return to Figure 5 Step 101 is repeated and steps 101 and 102 are performed and the system is in standby mode. Figure 5 If the judgment is yes in step 102, enter Figure 5 Step 103. Here, the first pressure PS1 is a predetermined set pressure for starting the condenser heat dissipation reduction process and can be freely set, for example, it can be set to about 70% to 80% of the engine starting pressure PE.

[0050] The control unit 80 Figure 5 In step 103, it is determined whether the ambient temperature detected by the ambient temperature sensor 57 is lower than the first temperature Tout1. The first temperature Tout1 is a temperature at which the engine 11 needs to be started when the ambient temperature is high so as to increase the heat dissipation from the condenser 42 and give priority to cooling the vehicle cabin. The first temperature Tout1 can be freely set, for example, it can be set to about 40°C to 45°C.

[0051] The control unit 80 Figure 5 If the judgment is yes in step 103, that is, if the ambient temperature is not high enough to give priority to the cooling of the cabin, the process proceeds to step Figure 5 Step 104, the condenser heat dissipation reduction process described later is performed, and the BEV continues to travel, and enters Figure 5 Step 105.

[0052] The control unit 80 Figure 5In step 105, it is determined whether the high cooler pressure is equal to or higher than the engine starting pressure PE. As described above, the engine starting pressure PE is the pressure that increases the heat dissipation of the condenser 42 by starting the engine 11 and entering the HEV mode due to the increase in the high cooler pressure.

[0053] The control unit 80 Figure 5 If the judgment is no in step 105, return to Figure 5 Step 101 is repeated to execute step 101 to step 105. At this time, the control unit 80 continues the BEV running with the engine 11 stopped.

[0054] On the other hand, the control unit 80 Figure 5 If the judgment is yes in step 105, enter Figure 5 In step 106, the engine 11 is started and the driving mode is changed from the BEV mode to the HEV mode. Figure 5 The condenser heat dissipation reduction process is stopped in step 107. When the engine 11 is started, the cooling fan 17 is activated, thereby increasing the air volume of the outside air passing through the condenser 42. As a result, the heat dissipation of the condenser 42 can be increased and the cooler high pressure can be reduced.

[0055] In addition, the control unit 80 Figure 5 If the judgment in step 103 is negative, that is, if the ambient temperature is above the first temperature Tout1, the process proceeds to step Figure 5 In step 106, the engine 11 is started and the driving mode is switched to the HEV mode, and in Figure 5 In step 107, the condenser heat dissipation reduction process is stopped.

[0056] Next, refer to Figure 6 ,right Figure 5 The condenser heat dissipation reduction process of step 104 will be described.

[0057] like Figure 6 As shown in step 201, the control unit 80 determines whether the switch damper 46 is switched to the internal air circulation. Figure 6 If the judgment in step 201 is yes, enter Figure 6 On the other hand, the control unit 80 Figure 6 If the judgment in step 201 is no, proceed to Figure 6 Step 202, the damper 46 is switched to internal air circulation, and the air is then Figure 6 Step 203.

[0058] The control unit 80 Figure 6In step 203, the duty cycle of the in-cabin fan 45 is increased. The duty cycle may be increased to a level where the occupants do not mind the noise of the fan, or may be increased to a maximum duty cycle.

[0059] In this way, as an internal air circulation, the flow rate of air circulating in the cabin is increased by increasing the duty cycle of the cabin fan 45, thereby keeping the temperature in the cabin low and reducing the heat dissipation of the condenser 42 without compromising the comfort of the occupants, thereby suppressing the rise in the cooler high pressure.

[0060] Next, the control unit 80 enters Figure 6 Step 204, apply Figure 2 The control map 83 shown increases the set value of the refrigerant temperature at the outlet of the evaporator 44 as the high cooler pressure increases. This can reduce the amount of heat exchange between the evaporator 44 and the air blown into the vehicle cabin, thereby reducing the load of the air conditioning device 200. Therefore, the amount of heat dissipated from the condenser 42 to the outside air can be reduced, and the high cooler pressure can be reduced.

[0061] In addition, the control unit 80 applies Figure 3 The control map 84 shown decreases the upper limit rotation speed of the compressor 41 as the cooler high pressure increases. As a result, the pressure of the refrigerant at the outlet of the compressor 41 decreases, and the cooler high pressure decreases.

[0062] Then, the control unit 80 enters Figure 6 In step 205, it is determined whether the high pressure of the cooler detected by the pressure sensor 55 is greater than the second pressure PS2. Here, the second pressure PS2 is a pressure slightly lower than the engine starting pressure PE. That is, the control unit 80 Figure 6 In the case where the cooler pressure still rises to a level close to the engine starting pressure PE after the processing of steps 201 to 204, Figure 6 In step 205, it is judged to be yes, and the process proceeds to Figure 6 Then, the control unit 80 performs the following steps: Figure 6 In step 206, apply Figure 4 The control map 85 shown in the figure reduces the duty ratio of the interior fan 45 as the refrigerant temperature at the outlet of the evaporator 44 increases, thereby reducing the air volume of the interior fan 45. As a result, the amount of heat exchange between the evaporator 44 and the air blown into the interior of the vehicle can be further reduced, thereby reducing the load of the air conditioning device 200. Therefore, the amount of heat dissipated from the condenser 42 to the outside air can be reduced, and the cooler high pressure can be further reduced.

[0063] On the other hand, the control unit 80 Figure 6 If the judgment in step 205 is no, no Figure 6 The process of step 206 is then completed, and the condenser heat dissipation reduction process is terminated.

[0064] As described above, the hybrid electric vehicle 100 of the embodiment reduces the heat dissipation of the condenser 42 during BEV driving, so it is possible to suppress the increase of the cooler high pressure during BEV driving and continue BEV driving. In addition, when the ambient temperature is high and cooling is required, the hybrid electric vehicle 100 of the embodiment can start the engine 11 to increase the heat dissipation of the condenser 42, thereby providing sufficient cooling.

[0065] In addition, the hybrid electric vehicle 100 of the embodiment improves the efficiency of the refrigeration cycle and reduces the heat dissipation of the condenser 42 by setting the inflow of air into the vehicle cabin as the internal air circulation and increasing the duty ratio of the in-cabin fan 45. Thus, the heat dissipation of the condenser 42 can be reduced without impairing the comfort of the passengers.

[0066] Furthermore, the hybrid electric vehicle 100 of the embodiment increases the refrigerant temperature setting value at the outlet of the evaporator 44 and decreases the upper limit rotation speed of the compressor 41 as the cooler high pressure increases. This can reduce the cooling load of the air conditioner 200 and reduce the heat dissipation of the condenser 42.

[0067] In addition, the hybrid electric vehicle 100 of the embodiment can further reduce the load of the air conditioning device 200 by reducing the duty ratio of the in-cabin fan 45, even if the efficiency of the refrigeration cycle is improved and the load of the air conditioning device 200 is reduced, while the cooler high pressure is still higher than the second pressure PS2 close to the engine starting pressure PE. Therefore, the increase of the cooler high pressure can be more effectively suppressed, and the driving in the BEV mode can be continued.

Claims

1. A hybrid electric vehicle capable of running in a hybrid mode in which the vehicle is driven by an engine and an electric motor and in a pure electric mode in which the engine is stopped and the vehicle is driven by the electric motor, and comprising: a radiator for cooling cooling water circulating inside the engine; An air conditioning device including a compressor, a condenser for condensing a refrigerant compressed by the compressor, and a pressure sensor for detecting a pressure of the refrigerant compressed by the compressor, and performing air conditioning in a vehicle cabin; a cooling fan that operates in response to the rotation of the engine and blows cooling air toward the radiator and the condenser; a control unit that controls the operation of the engine and the air conditioner, The control unit reduces the amount of heat dissipated by the condenser when the pressure of the refrigerant detected by the pressure sensor is equal to or higher than a predetermined first pressure during the travel in the pure electric mode.

2. The hybrid electric vehicle according to claim 1, wherein: When the pressure of the refrigerant detected by the pressure sensor is greater than or equal to the first pressure and the ambient temperature is less than a predetermined first temperature during driving in the pure electric mode, the control unit maintains the driving mode in the pure electric mode and reduces the heat dissipation of the condenser. When the pressure of the refrigerant detected by the pressure sensor is greater than the first pressure and the ambient temperature is greater than the first temperature while driving in the pure electric mode, the control unit starts the engine and switches the driving mode from the pure electric mode to the hybrid mode without reducing the heat dissipation of the condenser.

3. The hybrid electric vehicle according to claim 2, wherein: The air conditioning device includes a fan in the vehicle cabin and a switch damper. The fan in the compartment blows air into the compartment, The switching damper switches between external air introduction for introducing external air into the vehicle cabin and internal air circulation for circulating air in the vehicle cabin. The control unit reduces the amount of heat dissipated by the condenser by switching the switching damper to the inside air circulation and increasing the duty ratio of the in-cabin fan.

4. The hybrid electric vehicle according to claim 3, wherein: The air conditioning device includes an evaporator in which a refrigerant flows to cool air to be blown into a vehicle cabin. The control unit increases a set value of a refrigerant temperature at an evaporator outlet and decreases an upper limit rotation speed of the compressor as the pressure of the refrigerant detected by the pressure sensor increases, thereby reducing heat dissipation of the condenser.

5. The hybrid electric vehicle according to claim 4, wherein: When the pressure of the refrigerant detected by the pressure sensor is higher than a second pressure that is higher than the first pressure and lower than the engine starting pressure, the control unit reduces the duty cycle of the in-cabin fan as the refrigerant temperature at the evaporator outlet increases, thereby reducing the heat dissipation of the condenser.

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