Carbon dioxide heat pump direct cooling and heating integrated thermal management system for electric vehicle

Abstract

The application discloses a carbon dioxide heat pump direct cooling and direct heating type electric vehicle comprehensive heat management system and relates to the technical field of electric vehicle heat management. The operation modes of the system include: only passenger cabin refrigeration mode, passenger cabin refrigeration while battery cooling mode, passenger cabin refrigeration while motor and electric control equipment cooling mode, passenger cabin refrigeration while battery and motor and electric control equipment cooling mode, only battery cooling mode, only motor and electric control equipment cooling mode, only passenger cabin heating mode, passenger cabin heating while battery waste heat utilization mode, passenger cabin heating while motor and electric control equipment waste heat utilization mode, passenger cabin heating while battery and motor and electric control equipment waste heat utilization mode, passenger cabin heating while battery preheating mode and defogging and dehumidifying mode. The application selects corresponding operation modes based on the current electric vehicle operation condition, can realize the switching of multiple operation modes, and can improve the energy utilization efficiency of the system under different operation conditions.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle thermal management technology, and in particular to a carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles. Background Technology

[0002] Currently, in CO2 heat pump-based electric vehicle thermal management systems, battery cooling primarily utilizes a secondary loop. This secondary loop suffers from significant heat transfer losses and noticeable thermal hysteresis, leading to prolonged thermal management time. Furthermore, in current transcritical CO2 systems operating in battery heating mode, the working fluid entering the battery heat exchanger is in a supercritical state. This state results in a large temperature glide in the CO2 working fluid, causing uneven heating of the battery.

[0003] The driving range of an electric vehicle is determined by the battery's operating characteristics, which are affected by the temperature field. Meanwhile, the heat generated by the motor and electronic control equipment during operation can be utilized as waste heat. Therefore, the thermal management system of an electric vehicle needs to manage the battery, motor, electronic control equipment, and passenger compartment in a unified manner.

[0004] Electric vehicles operate in various modes. A sophisticated electric vehicle thermal management system needs to be able to control the temperature of the passenger compartment and, based on the current operating conditions of the electric vehicle, select the optimal thermal management mode to achieve the highest energy utilization efficiency under various circumstances. Therefore, the development of a multi-mode electric vehicle thermal management system requires further discussion. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles, which can realize the switching of multiple operating modes. Multiple operating modes can improve the energy utilization efficiency of the system under different operating conditions.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A carbon dioxide heat pump direct cooling and direct heating type integrated thermal management system for electric vehicles, the system comprising: a compressor 1, a first four-way reversing valve 2, a first diverter valve 3, a second diverter valve 4, a second four-way reversing valve 5, a first three-way valve 6, a second three-way valve 7, a third three-way valve 8, a fourth three-way valve 9, a first expansion valve 10, a second expansion valve 11, a third expansion valve 12, a fourth expansion valve 13, a fifth expansion valve 14, a sixth expansion valve 15, a regenerator 16, a gas-liquid separator 17, an outdoor heat exchanger 18, an indoor heat exchanger 19, a battery 20, motor and electrical control equipment 21, an indoor secondary heat exchanger 22, and a seventh expansion valve 23.

[0008] The first four-way reversing valve 2 has port a connected to the outlet of compressor 1, port b connected to port a of the second diverter valve 4, port c connected to the first vent of indoor heat exchanger 19, and port d connected to port b of the second three-way valve 7.

[0009] The a port of the second three-way valve 7 is connected to the b port of the first three-way valve 6, and the c port of the second three-way valve 7 is connected to the first port of the second expansion valve 11; the second port of the second expansion valve 11 is connected to the b port of the fourth three-way valve 9, the a port of the fourth three-way valve 9 is connected to the first vent of the outdoor heat exchanger 18, and the c port of the fourth three-way valve 9 is connected to the a port of the second four-way reversing valve 5; the second vent of the outdoor heat exchanger 18 is connected to the b port of the third three-way valve 8, the a port of the third three-way valve 8 is connected to the b port of the first diverter valve 3 via the first heat exchange channel of the regenerator 16, and the c port of the third three-way valve 8 is connected to the d port of the second four-way reversing valve 5; the b port of the second four-way reversing valve 5 is connected to the inlet of the gas-liquid separator 17, and the outlet of the gas-liquid separator 17 is connected to the inlet of the compressor 1.

[0010] The first three-way valve 6 has port a connected to the first port of the first expansion valve 10, and port c of the first three-way valve 6 is connected to port a of the first diversion valve 3; the second port of the first expansion valve 10 is connected to the first vent of the indoor secondary heat exchanger 22, the second vent of the indoor secondary heat exchanger 22 is connected to the first port of the seventh expansion valve 23, and the second port of the seventh expansion valve 23 is connected to the second vent of the indoor heat exchanger 19.

[0011] The b port of the second diversion valve 4 is connected to the c port of the second four-way reversing valve 5 via the second heat exchange channel of the regenerator 16. The c port of the second diversion valve 4 is connected to the first port of the fourth expansion valve 13. The d port of the second diversion valve 4 is connected to the first port of the sixth expansion valve 15. The c port of the first diversion valve 3 is connected to the first port of the third expansion valve 12. The d port of the first diversion valve 3 is connected to the first port of the fifth expansion valve 14.

[0012] The second port of the third expansion valve 12 is connected to the inlet of the heat exchange device of the battery 20; the second port of the fourth expansion valve 13 is connected to the outlet of the heat exchange device of the battery 20; the second port of the fifth expansion valve 14 is connected to the inlet of the heat exchange device of the motor control device 21; and the second port of the sixth expansion valve 15 is connected to the outlet of the heat exchange device of the motor control device 21.

[0013] The system's operating modes include: passenger cabin cooling only, passenger cabin cooling and battery cooling simultaneously, passenger cabin cooling and motor / control equipment cooling simultaneously, passenger cabin cooling and battery / motor / control equipment cooling simultaneously, battery cooling only, motor / control equipment cooling only, passenger cabin heating only, passenger cabin heating and battery waste heat utilization simultaneously, passenger cabin heating and motor / control equipment waste heat utilization simultaneously, passenger cabin heating and battery preheating simultaneously, and defogging / dehumidification mode.

[0014] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] This invention discloses a carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles. The system's operating modes include: passenger compartment cooling only; passenger compartment cooling and battery cooling simultaneously; passenger compartment cooling and motor / control equipment cooling simultaneously; passenger compartment cooling and battery / motor / control equipment cooling simultaneously; battery cooling only; motor / control equipment cooling only; passenger compartment heating only; passenger compartment heating and battery waste heat utilization simultaneously; passenger compartment heating and battery / motor / control equipment waste heat utilization simultaneously; passenger compartment heating and battery preheating simultaneously; and defogging / dehumidification mode. Based on the current operating conditions of the electric vehicle, the corresponding operating mode can be selected, enabling switching between multiple operating modes. These multiple operating modes can improve the system's energy utilization efficiency under different operating conditions.

[0016] In passenger compartment cooling mode, the system can dissipate heat for the battery and motor / control equipment individually or simultaneously. Even when passenger compartment heating is not required, the system can still dissipate heat for either the battery or the motor / control equipment independently. In passenger compartment heating mode, the system can recover heat from the battery and motor / control equipment individually or simultaneously to heat the passenger compartment. Under winter start-up conditions, the system can preheat the battery, mitigating the reduced driving range caused by low initial battery temperature. Furthermore, in preheating mode, the battery's heat exchanger is connected in series with the interior heat exchanger. By controlling the CO2 working fluid entering the battery's heat exchanger to operate in a subcritical cycle, the system improves temperature uniformity during battery heat exchange and enhances heat exchange performance. The direct cooling and heating technology offers the advantage of a compact structure. Simultaneously, the ability to directly exchange heat between the CO2 working fluid and the battery improves heat exchange efficiency, facilitates energy distribution control, and enhances the response speed of thermal management. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram illustrating the working principle of the crew cabin-only cooling mode provided in an embodiment of the present invention.

[0020] Figure 3 A schematic diagram illustrating the working principle of the simultaneous cooling of the passenger compartment and the battery, provided in an embodiment of the present invention.

[0021] Figure 4 A schematic diagram illustrating the working principle of the simultaneous cooling mode of the passenger cabin and the motor and electronic control equipment provided in this embodiment of the invention;

[0022] Figure 5 A schematic diagram illustrating the working principle of the simultaneous cooling mode of the passenger compartment and the battery, motor, and electronic control equipment provided in this embodiment of the invention.

[0023] Figure 6 This is a schematic diagram illustrating the working principle of the battery-only cooling mode provided in an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram illustrating the working principle of the cooling mode for motor-controlled equipment only, provided in an embodiment of the present invention.

[0025] Figure 8 This is a schematic diagram illustrating the working principle of the crew cabin heating mode provided in an embodiment of the present invention.

[0026] Figure 9 This is a schematic diagram illustrating the working principle of the passenger compartment heating and battery waste heat utilization mode provided in an embodiment of the present invention.

[0027] Figure 10 A schematic diagram illustrating the working principle of the waste heat utilization mode of the motor and electronic control equipment for heating the passenger compartment in an embodiment of the present invention.

[0028] Figure 11 A schematic diagram illustrating the working principle of the passenger compartment heating and waste heat utilization mode of the battery, motor and electronic control equipment provided in an embodiment of the present invention.

[0029] Figure 12 This is a schematic diagram illustrating the working principle of the simultaneous crew cabin heating and battery preheating mode provided in an embodiment of the present invention.

[0030] Figure 13 This is a schematic diagram illustrating the working principle of the defogging and dehumidification mode provided in an embodiment of the present invention.

[0031] Symbol explanation:

[0032] Compressor-1, First four-way reversing valve-2, First diverter valve-3, Second diverter valve-4, Second four-way reversing valve-5, First three-way valve-6, Second three-way valve-7, Third three-way valve-8, Fourth three-way valve-9, First expansion valve-10, Second expansion valve-11, Third expansion valve-12, Fourth expansion valve-13, Fifth expansion valve-14, Sixth expansion valve-15, Regenerator-16, Gas-liquid separator-17, Outdoor heat exchanger-18, Indoor heat exchanger-19, Battery-20, Motor and electrical control equipment-21, Indoor secondary heat exchanger-22 and Seventh expansion valve-23, Indoor fan-24, Outdoor fan-25. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown in this embodiment, a carbon dioxide heat pump direct cooling and direct heating type electric vehicle integrated thermal management system includes: compressor 1, first four-way reversing valve 2, first diverter valve 3, second diverter valve 4, second four-way reversing valve 5, first three-way valve 6, second three-way valve 7, third three-way valve 8, fourth three-way valve 9, first expansion valve 10, second expansion valve 11, third expansion valve 12, fourth expansion valve 13, fifth expansion valve 14, sixth expansion valve 15, regenerator 16, gas-liquid separator 17, outdoor heat exchanger 18, indoor heat exchanger 19, battery 20, motor and electrical control equipment 21, indoor secondary heat exchanger 22, and seventh expansion valve 23.

[0036] The first four-way reversing valve 2 has port a connected to the outlet of compressor 1, port b connected to port a of the second diverter valve 4, port c connected to the first vent of indoor heat exchanger 19, and port d connected to port b of the second three-way valve 7.

[0037] The a port of the second three-way valve 7 is connected to the b port of the first three-way valve 6, and the c port of the second three-way valve 7 is connected to the first port of the second expansion valve 11; the second port of the second expansion valve 11 is connected to the b port of the fourth three-way valve 9, the a port of the fourth three-way valve 9 is connected to the first vent of the outdoor heat exchanger 18, and the c port of the fourth three-way valve 9 is connected to the a port of the second four-way reversing valve 5; the second vent of the outdoor heat exchanger 18 is connected to the b port of the third three-way valve 8, the a port of the third three-way valve 8 is connected to the b port of the first diverter valve 3 via the first heat exchange channel of the regenerator 16, and the c port of the third three-way valve 8 is connected to the d port of the second four-way reversing valve 5; the b port of the second four-way reversing valve 5 is connected to the inlet of the gas-liquid separator 17, and the outlet of the gas-liquid separator 17 is connected to the inlet of the compressor 1.

[0038] The first three-way valve 6 has port a connected to the first port of the first expansion valve 10, and port c of the first three-way valve 6 is connected to port a of the first diversion valve 3; the second port of the first expansion valve 10 is connected to the first vent of the indoor secondary heat exchanger 22, the second vent of the indoor secondary heat exchanger 22 is connected to the first port of the seventh expansion valve 23, and the second port of the seventh expansion valve 23 is connected to the second vent of the indoor heat exchanger 19.

[0039] The b port of the second diversion valve 4 is connected to the c port of the second four-way reversing valve 5 via the second heat exchange channel of the regenerator 16. The c port of the second diversion valve 4 is connected to the first port of the fourth expansion valve 13. The d port of the second diversion valve 4 is connected to the first port of the sixth expansion valve 15. The c port of the first diversion valve 3 is connected to the first port of the third expansion valve 12. The d port of the first diversion valve 3 is connected to the first port of the fifth expansion valve 14.

[0040] The second port of the third expansion valve 12 is connected to the inlet of the heat exchange device of the battery 20; the second port of the fourth expansion valve 13 is connected to the outlet of the heat exchange device of the battery 20; the second port of the fifth expansion valve 14 is connected to the inlet of the heat exchange device of the motor control device 21; and the second port of the sixth expansion valve 15 is connected to the outlet of the heat exchange device of the motor control device 21.

[0041] The system's operating modes include: passenger cabin cooling only, passenger cabin cooling and battery cooling simultaneously, passenger cabin cooling and motor / control equipment cooling simultaneously, passenger cabin cooling and battery / motor / control equipment cooling simultaneously, battery cooling only, motor / control equipment cooling only, passenger cabin heating only, passenger cabin heating and battery waste heat utilization simultaneously, passenger cabin heating and motor / control equipment waste heat utilization simultaneously, passenger cabin heating and battery preheating simultaneously, and defogging / dehumidification mode.

[0042] The outdoor heat exchanger 18 is a heat exchange device used for heat exchange between the outside of the passenger compartment and the air. The indoor heat exchanger 19 and the indoor secondary heat exchanger 22 are heat exchange devices used for heat exchange between the inside of the passenger compartment and the air. The battery 20 has a heat exchange device for providing the battery with the required cooling and heating. The motor and electrical control equipment 21 has a heat exchange device for providing the motor and electrical control equipment with the required cooling and heating. Figure 1 The system also includes an indoor fan 24 and an outdoor fan 25. The indoor fan 24 is a device for driving indoor airflow, and the outdoor fan 25 is a device for driving outdoor airflow.

[0043] Figure 2 This is a schematic diagram illustrating the working principle of the crew cabin-only cooling mode. Figure 2 As shown, when the system operates in the crew cabin-only cooling mode, ports a and d of the first four-way reversing valve 2 are connected; ports b and c of the second three-way valve 7 are connected; the second expansion valve 11 is open; ports b and a of the fourth three-way valve 9 and the third three-way valve 8 are connected; ports b and a of the first diversion valve 3 are connected; ports c and a of the first three-way valve 6 are connected; the first expansion valve 10 is in a throttling state; and the seventh expansion valve 23 is open; ports c and b of the first four-way reversing valve 2 are connected; ports a and b of the second diversion valve 4 and the second four-way reversing valve 5 are connected. The CO2 working fluid is compressed by compressor 1, flows through ports a and d of the first four-way reversing valve 2, ports b and c of the second three-way valve 7, the second expansion valve 11, ports b and a of the fourth three-way valve 9, and the outdoor heat exchanger 18 to release heat. Then it flows through ports b and a of the third three-way valve 8, the regenerator 16, ports b and a of the first diversion valve 3, ports c and a of the first three-way valve 6, and then through the first expansion valve 10 to reduce pressure and temperature. It then flows through the indoor heat exchanger 19 and the indoor secondary heat exchanger 22 to achieve the occupant cabin cooling function. Finally, it flows back to compressor 1 through ports c and b of the first four-way reversing valve 2, ports a and b of the second diversion valve 4, ports c and b of the second four-way reversing valve 5, and the gas-liquid separator 17.

[0044] The control methods for crew cabin-only cooling mode include:

[0045] With the air-side outlet temperature of the indoor heat exchanger 19 as the target quantity and the speed of the compressor 1 as the control quantity, the speed of the compressor 1 is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value of the air-side outlet temperature of the indoor heat exchanger.

[0046] With the discharge pressure of compressor 1 as the target quantity and the opening degree of the first expansion valve 10 as the control quantity, the opening degree of the first expansion valve 10 is adjusted by PID control method so that the discharge pressure of compressor 1 reaches the optimal pressure setting value under the current working condition.

[0047] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, and P be the discharge pressure of the compressor 1. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, and the method of obtaining it includes, but is not limited to, the empirical correlation method and the intelligent optimization control method.

[0048] Figure 3 A schematic diagram illustrating the working principle of the simultaneous cooling of the passenger compartment and the battery cooling mode. Figure 3 As shown, when the system operates in the passenger compartment cooling and battery cooling mode, port a and port d of the first four-way reversing valve 2 are connected, and port b and port c of the second three-way valve 7 are connected; the second expansion valve 11 is open, port b and port a of the fourth three-way valve 9 are connected, and port b and port a of the third three-way valve 8 are connected; port b of the first diverter valve 3 is connected to port a and port c respectively; the third expansion valve 12 is in a throttling state, and the fourth expansion valve 13 is in an open state; port c and port a of the first three-way valve 6 are connected, the first expansion valve 10 is in a throttling state, the seventh expansion valve 23 is in an open state, port c and port b of the first four-way reversing valve 2 are connected, ports a, c and b of the second diverter valve 4 are connected, and port c and port b of the second four-way reversing valve 5 are connected. The CO2 working fluid enters from port b of the first diversion valve 3 and splits into two paths, port a and port c. One path flows into the battery 20 through the third expansion valve 12 for throttling, depressurization, and cooling, thus cooling the battery 20, and then flows into the fourth expansion valve 13. The other path is the same as the refrigeration mode for the crew cabin only. The two paths merge through ports a and c of the second diversion valve 4, and then flow back to the compressor 1 through port b, ports c and b of the second four-way reversing valve 5, and gas-liquid separator 17.

[0049] The control methods for simultaneous crew cabin cooling and battery cooling modes include:

[0050] With the air-side outlet temperature of the indoor heat exchanger 19 as the target quantity and the speed of the compressor 1 as the control quantity, the speed of the compressor 1 is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value of the air-side outlet temperature of the indoor heat exchanger.

[0051] With the discharge pressure of compressor 1 as the target quantity and the opening degree of the first expansion valve 10 as the control quantity, the PID control method is used to adjust the opening degree of the first expansion valve 10 so that the discharge pressure of compressor 1 reaches the optimal pressure under the current operating conditions.

[0052] With the dryness of the working fluid at the outlet of the heat exchanger of battery 20 as the target quantity and the opening degree of the third expansion valve 12 as the control quantity, the opening degree of the third expansion valve 12 is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchanger of battery 20 reaches the optimal dryness of the outlet of the heat exchanger of battery 20.

[0053] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, P be the exhaust pressure of the compressor 1, and x1 be the dryness of the working fluid at the outlet of the heat exchange device of the battery 20. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, and its acquisition method includes, but is not limited to, the empirical correlation method and the intelligent optimization control method; x1 is the optimal dryness of the outlet of the heat exchange device of the battery 20 under empirical conditions.

[0054] Figure 4 A schematic diagram illustrating the working principle of a mode that simultaneously cools the passenger compartment and the motors and electronic control equipment. (See diagram below.) Figure 4 As shown, when the system operates in the mode of refrigerating the passenger compartment while simultaneously cooling the motor and electronic control equipment, ports a and d of the first four-way directional valve 2 are connected; ports b and c of the second three-way valve 7 are connected; the second expansion valve 11 is open; ports b and a of the fourth three-way valve 9 are connected; ports b and a of the third three-way valve 8 are connected; ports b, a, and d of the first diverter valve 3 are connected; the fifth expansion valve 14 is in a throttling state; the sixth expansion valve 15 is in an open state; ports c and a of the first three-way valve 6 are connected; the first expansion valve 10 is in a throttling state; the seventh expansion valve 23 is in an open state; ports c and b of the first four-way directional valve 2 are connected; ports a, d, and b of the second diverter valve 4 are connected; and ports c and b of the second four-way directional valve 5 are connected. The CO2 working fluid enters from port b of the first diversion valve 3 and splits into two paths, port a and port d. One path flows into the motor and electrical control equipment 21 through the fifth expansion valve 14 for throttling, depressurization, and cooling, thus achieving its cooling function, and then flows into the sixth expansion valve 15. The other path is the same as the refrigeration mode for the crew cabin only. The two paths merge through ports a and d of the second diversion valve 4, and then flow back to the compressor 1 through port b, ports c and b of the second four-way reversing valve 5, and gas-liquid separator 17.

[0055] The control methods for the cooling mode of the crew cabin and the motor and electronic control equipment include:

[0056] With the air-side outlet temperature of the indoor heat exchanger 19 as the target quantity and the speed of the compressor 1 as the control quantity, the speed of the compressor 1 is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value of the air-side outlet temperature of the indoor heat exchanger.

[0057] With the discharge pressure of compressor 1 as the target quantity and the opening degree of the first expansion valve 10 as the control quantity, the PID control method is used to adjust the opening degree of the first expansion valve 10 so that the discharge pressure of compressor 1 reaches the optimal pressure under the current operating conditions.

[0058] With the dryness of the working fluid at the outlet of the heat exchanger of the motor and electrical control equipment 21 as the target quantity and the opening degree of the fifth expansion valve 14 as the control quantity, the PID control method is used to adjust the opening degree of the fifth expansion valve 14 so that the dryness of the working fluid at the outlet of the heat exchanger of the motor and electrical control equipment 21 reaches the optimal dryness of the outlet of the heat exchanger of the motor and electrical control equipment 21.

[0059] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, P be the exhaust pressure of the compressor 1, and x2 be the dryness of the working fluid at the outlet of the heat exchange device of the motor and electrical control equipment 21. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, which can be obtained by methods including but not limited to empirical correlation methods and intelligent optimization control methods; x2 is the empirical optimal dryness of the outlet of the motor heat exchange device.

[0060] Figure 5 A schematic diagram illustrating the working principle of a mode that simultaneously cools the passenger compartment and the battery, motor, and electronic control equipment. (See diagram for example.) Figure 5 As shown, when the system operates in the mode of occupant cabin cooling while simultaneously cooling the battery, motor, and electronic control equipment, ports a and d of the first four-way directional valve 2 are connected; ports b and c of the second three-way valve 7 are connected; the second expansion valve 11 is open; ports b and a of the fourth three-way valve 9 are connected; ports b and a of the third three-way valve 8 are connected; ports b of the first diverter valve 3 are connected to ports a, d, and c; the fifth expansion valve 14 is in a throttling state; the sixth expansion valve 15 is in an open state; the third expansion valve 12 is in a throttling state; the fourth expansion valve 13 is in an open state; ports c and a of the first three-way valve 6 are connected; the first expansion valve 10 is in a throttling state; the seventh expansion valve 23 is in an open state; ports c and b of the first four-way directional valve 2 are connected; ports a, d, and c of the second diverter valve 4 are connected to port b; and ports c and d of the second four-way directional valve 5 are connected. The CO2 working fluid enters from port a of the first diversion valve 3 and splits into three paths: port b, port c, and port d. One path is the same as the refrigeration mode for the crew cabin only; another path flows into the battery 20 through the third expansion valve 12 for throttling, depressurization, and cooling, and then flows into the fourth expansion valve 13; the third path flows into the motor and electrical control equipment 21 through the fifth expansion valve 14 for throttling, depressurization, and cooling, and then flows into the sixth expansion valve 15; the three paths converge through ports a, c, and d of the second diversion valve 4, and then flow back to the compressor 1 through port b, ports c and b of the second four-way reversing valve 5, and the gas-liquid separator 17.

[0061] The control methods for cooling the crew cabin while simultaneously cooling the battery, motor, and electronic control equipment include:

[0062] With the air-side outlet temperature of the indoor heat exchanger 19 as the target quantity and the speed of the compressor 1 as the control quantity, the speed of the compressor 1 is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value of the air-side outlet temperature of the indoor heat exchanger.

[0063] With the discharge pressure of compressor 1 as the target quantity and the opening degree of the first expansion valve 10 as the control quantity, the PID control method is used to adjust the opening degree of the first expansion valve 10 so that the discharge pressure of compressor 1 reaches the optimal pressure under the current operating conditions.

[0064] With the dryness of the working fluid at the outlet of the heat exchanger of battery 20 as the target quantity and the opening degree of the third expansion valve 12 as the control quantity, the opening degree of the third expansion valve 12 is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchanger of battery 20 reaches the optimal dryness of the outlet of the heat exchanger of battery 20.

[0065] With the dryness of the working fluid at the outlet of the heat exchanger of the motor and electrical control equipment 21 as the target quantity and the opening degree of the fifth expansion valve 14 as the control quantity, the PID control method is used to adjust the opening degree of the fifth expansion valve 14 so that the dryness of the working fluid at the outlet of the heat exchanger of the motor and electrical control equipment 21 reaches the optimal dryness of the outlet of the heat exchanger of the motor and electrical control equipment 21.

[0066] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, P be the exhaust pressure of the compressor 1, x1 be the dryness of the working fluid at the outlet of the heat exchange device of the battery 20, and x2 be the dryness of the working fluid at the outlet of the heat exchange device of the motor and electronic control equipment 21. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, and its acquisition method includes, but is not limited to, the empirical correlation method and the intelligent optimization control method; x1 and x2 are the empirical optimal dryness of the outlet of the battery and motor heat exchange devices.

[0067] Figure 6 This is a schematic diagram illustrating the working principle of the battery-only cooling mode. Figure 6 As shown, when the system operates in battery-only cooling mode, ports a and d of the first four-way reversing valve 2 are connected; ports b and c of the second three-way valve 7 are connected; the second expansion valve 11 is open; ports b and a of the fourth three-way valve 9 and the third three-way valve 8 are connected; ports b and c of the first diverter valve 3 are connected; the third expansion valve 12 is in a throttling state; the fourth expansion valve 13 is in an open state; ports c and b of the second diverter valve 4 and the second four-way reversing valve 5 are connected. CO2 working fluid enters from port b of the first diverter valve 3 and exits from port c. After being throttled and depressurized by the third expansion valve 12, it flows into the battery 20 to achieve battery cooling, and then flows into the fourth expansion valve 13; it flows in through port c and out through port b of the second diverter valve 4, passes through ports c and b of the second four-way reversing valve 5, and then flows back to the compressor 1 after passing through the gas-liquid separator 17.

[0068] The control methods for battery-only cooling mode include:

[0069] When the temperature of battery 20 rises to the set temperature, compressor 1 is activated. That is, the speed of compressor 1 is controlled by the temperature of battery 20.

[0070] With the discharge pressure of compressor 1 as the target quantity and the opening degree of the third expansion valve 12 as the control quantity, the PID control method is used to adjust the opening degree of the third expansion valve 12 so that the discharge pressure of compressor 1 reaches the optimal pressure under the current operating conditions.

[0071] For example, let the temperature of battery 20 be T2, the discharge pressure of compressor 1 be P, the speed of compressor 1 be N, and P be the optimal pressure under the current operating conditions. The method for obtaining P includes, but is not limited to, the empirical correlation method and the intelligent optimization control method.

[0072] Figure 7 This is a schematic diagram illustrating the working principle of the cooling mode for only the motor and electronic control equipment. Figure 7 As shown, when the system operates in the mode of cooling only the motor and electrical control equipment, ports a and d of the first four-way directional valve 2 are connected; ports b and c of the second three-way valve 7 are connected; the second expansion valve 11 is open; ports b and a of the fourth three-way valve 9 and the third three-way valve 8 are connected; ports b and d of the first diverter valve 3 are connected; the fifth expansion valve 14 is in a throttling state; the sixth expansion valve 15 is in an open state; ports d and b of the second diverter valve 4 and ports c and b of the second four-way directional valve 5 are connected. CO2 working fluid enters from port a and exits from port d of the first diverter valve 3, flows into the motor and electrical control equipment 21 through the fifth expansion valve 14 (throttling, depressurization, and cooling) to achieve the cooling function of the motor and electrical control equipment 21, and then flows into the sixth expansion valve 15; it flows in through port d and out through port b of the second diverter valve 4, passes through ports c and b of the second four-way directional valve 5, and then flows back to the compressor 1 after passing through the gas-liquid separator 17.

[0073] Control methods for the cooling mode of motor-controlled equipment only include:

[0074] When the temperature of the motor control device 21 rises to the set temperature, the compressor 1 is activated. That is, the speed of the compressor 1 is controlled by the temperature of the motor control device 21.

[0075] Using the discharge pressure of compressor 1 as the target quantity and the opening degree of the fifth expansion valve 14 as the control quantity, a PID control method is used to adjust the opening degree of the fifth expansion valve 14 so that the discharge pressure of compressor 1 reaches the optimal pressure under the current operating conditions. That is, a PID regulation relationship is established between the opening degree of the fifth expansion valve 14 and the discharge pressure of compressor 1.

[0076] For example, let the temperature of the motor control device 21 be T3, the discharge pressure of the compressor 1 be P, and the speed be N. P is the optimal pressure under the current operating conditions. The method for obtaining P includes, but is not limited to, the empirical correlation method and the intelligent optimization control method.

[0077] Figure 8 This is a schematic diagram illustrating the working principle of the crew cabin-only heating mode. Figure 8As shown, when the system is in crew cabin heating mode only, port a and port c of the first four-way directional valve 2 are connected, the seventh expansion valve 23 is open, the first expansion valve 10 is open, port a and port b of the first three-way valve 6 are connected, port a and port c of the second three-way valve 7 are connected, the second expansion valve 11 is in throttling mode, port b and port a of the fourth three-way valve 9 are connected, port b and port c of the third three-way valve 8 are connected, and port d and port b of the second four-way directional valve 5 are connected. After being compressed by compressor 1, CO2 flows into indoor heat exchanger 19 and indoor secondary heat exchanger 22 through ports a and c of the first four-way reversing valve 2 to achieve the heating function of the crew cabin. After passing through ports a and b of the first three-way valve 6 and ports a and c of the second three-way valve 7, it flows into the second expansion valve 11 for throttling, cooling and depressurization. Then, it flows into outdoor heat exchanger 18 through ports b and a of the fourth three-way valve 9 to absorb heat. Finally, it flows back to compressor 1 through ports b and c of the third three-way valve 8, ports b and d of the second four-way reversing valve 5, and gas-liquid separator 17.

[0078] The control methods for crew cabin heating mode only include:

[0079] Using the air-side outlet temperature of the indoor heat exchanger 19 as the target variable and the speed of the compressor 1 as the control variable, a PID control method is used to adjust the speed of the compressor 1 so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value. That is, a PID regulation relationship is established between the speed of the compressor 1 and the air-side outlet temperature of the indoor heat exchanger 19.

[0080] Using the discharge pressure of compressor 1 as the target quantity and the opening degree of the second expansion valve 11 as the control quantity, a PID control method is used to adjust the opening degree of the second expansion valve 11 so that the discharge pressure of compressor 1 reaches the optimal pressure under the current operating conditions. That is, a PID regulation relationship is established between the opening degree of the second expansion valve 11 and the discharge pressure of compressor 1.

[0081] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, and P be the discharge pressure of the compressor 1. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, and the method of obtaining it includes, but is not limited to, the empirical correlation method and the intelligent optimization control method.

[0082] Figure 9 A schematic diagram illustrating the working principle of a mode that simultaneously heats the passenger compartment and utilizes waste battery heat. (For example...) Figure 9As shown, when the system operates in the mode of crew cabin heating and battery waste heat utilization, port a and port c of the first four-way reversing valve 2 are connected, the seventh expansion valve 23 is in the open state, and the first expansion valve 10 is in the open state; port a and port c of the first three-way valve 6 are connected, port a and port c of the first diversion valve 3 are connected, the third expansion valve 12 is in the throttling state, the fourth expansion valve 13 is in the open state, port c and port b of the second diversion valve 4 are connected, and port c and port b of the second four-way reversing valve 5 are connected. After being compressed by compressor 1, CO2 working fluid flows into indoor heat exchanger 19 and indoor secondary heat exchanger 22 through ports a and c of the first four-way reversing valve 2, achieving the heating function of the crew cabin. Then it flows into the first expansion valve 10 and into port a and out through port c of the first three-way valve 6. After passing through ports a and c of the first diversion valve 3, it flows into the third expansion valve 12 for throttling, cooling and depressurization. At this time, the heat exchange device of battery 20 replaces the outdoor heat exchanger 18 to release heat to the working fluid. Then it flows back to compressor 1 through ports c and b of the second diversion valve 4, ports c and b of the second four-way reversing valve 5, and gas-liquid separator 17.

[0083] The control methods for the simultaneous crew cabin heating and battery waste heat utilization mode include:

[0084] Using the air-side outlet temperature of the indoor heat exchanger 19 as the target variable and the speed of the compressor 1 as the control variable, a PID control method is used to adjust the speed of the compressor 1 so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value. That is, a PID regulation relationship is established between the speed of the compressor 1 and the air-side outlet temperature of the indoor heat exchanger 19.

[0085] Using the dryness of the working fluid at the outlet of the heat exchanger of battery 20 as the target quantity and the opening degree of the third expansion valve 12 as the control quantity, a PID control method is used to adjust the opening degree of the third expansion valve 12 so that the dryness of the working fluid at the outlet of the heat exchanger of battery 20 reaches the optimal dryness of the heat exchanger of battery 20. That is, a PID control relationship is established between the opening degree of the third expansion valve 12 and the dryness of the working fluid at the outlet of the heat exchanger of battery 20.

[0086] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, P be the exhaust pressure of the compressor 1, and x1 be the dryness of the working fluid at the outlet of the heat exchange device of the battery 20. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, which can be obtained by methods including but not limited to empirical correlation methods and intelligent optimization control methods; x1 is the empirical optimal dryness of the outlet of the heat exchange device of the battery 20.

[0087] Figure 10 A schematic diagram illustrating the working principle of a mode that utilizes waste heat from motors and electronic control equipment while heating the passenger compartment. Figure 10As shown, when the system operates in the mode of crew cabin heating and waste heat utilization of motor and electrical control equipment, port a and port c of the first four-way reversing valve 2 are connected, the seventh expansion valve 23 is in the open state, and the first expansion valve 10 is in the open state; port a and port c of the first three-way valve 6 are connected, port a and port d of the first diversion valve 3 are connected, the fifth expansion valve 14 is in the throttling state, the sixth expansion valve 15 is in the open state, port d and port b of the second diversion valve 4 are connected, and port c and port b of the second four-way reversing valve 5 are connected. After being compressed by compressor 1, CO2 flows into indoor heat exchanger 19 and indoor secondary heat exchanger 22 through ports a and c of the first four-way reversing valve 2, thus heating the passenger compartment. It then flows into the first expansion valve 10 and into port a and out through port c of the first three-way valve 6. After passing through ports a and d of the first diversion valve 3, it flows into the fifth expansion valve 14 for throttling, cooling and depressurization. At this time, the heat exchange device of the motor and electrical control equipment 21 replaces the outdoor heat exchanger 18 to release heat to the CO2 working fluid. After passing through ports d and b of the second diversion valve 4, ports c and b of the second four-way reversing valve 5, and gas-liquid separator 17, it flows back to compressor 1.

[0088] The control methods for the simultaneous heating of the crew cabin and the utilization of waste heat from the motor and electronic control equipment include:

[0089] Using the air-side outlet temperature of the indoor heat exchanger 19 as the target variable and the speed of the compressor 1 as the control variable, a PID control method is used to adjust the speed of the compressor 1 so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value. That is, a PID regulation relationship is established between the speed of the compressor 1 and the air-side outlet temperature of the indoor heat exchanger 19.

[0090] Using the dryness of the working fluid at the outlet of the heat exchanger of the motor and electronic control equipment 21 as the target quantity and the opening degree of the fifth expansion valve 14 as the control quantity, a PID control method is used to adjust the opening degree of the fifth expansion valve 14 so that the dryness of the working fluid at the outlet of the heat exchanger of the motor and electronic control equipment 21 reaches the optimal dryness of the heat exchanger outlet of the motor and electronic control equipment 21. That is, a PID control relationship is established between the opening degree of the fifth expansion valve 14 and the dryness of the working fluid at the outlet of the heat exchanger of the motor and electronic control equipment 21.

[0091] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, P be the discharge pressure of the compressor 1, and x2 be the dryness of the working fluid at the outlet of the heat exchange device of the motor and electronic control equipment 21. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, which can be obtained by methods including but not limited to empirical correlation methods and intelligent optimization control methods; x2 is the empirical optimal dryness of the outlet of the heat exchange device of the motor and electronic control equipment 21.

[0092] Figure 11 A schematic diagram illustrating the working principle of a mode that utilizes waste heat from batteries, motors, and electronic control equipment while simultaneously heating the passenger compartment. Figure 11As shown, when the system operates in the mode of crew cabin heating while utilizing waste heat from the battery, motor, and electronic control equipment, ports a and c of the first four-way reversing valve 2 are connected, the seventh expansion valve 23 is open, and the first expansion valve 10 is open; ports a and c of the first three-way valve 6 are connected; ports a, c, and d of the first diverter valve 3 are connected; the third expansion valve 12 is in a throttling state, and the fourth expansion valve 13 is open; the fifth expansion valve 14 is in a throttling state, and the sixth expansion valve 15 is open; ports d and c of the second diverter valve 4 are connected to port b, and ports c and b of the second four-way reversing valve 5 are connected. After being compressed by compressor 1, CO2 flows into indoor heat exchanger 19 and indoor secondary heat exchanger 22 through ports a and c of the first four-way reversing valve 2, thus heating the passenger compartment. It then flows into port a of the first expansion valve 10 and port c of the first three-way valve 6. After passing through port a of the first diverter valve 3, it splits into two paths. One path flows from port c into the third expansion valve 12 for throttling, cooling, and depressurization. At this time, the heat exchange device of battery 20 replaces the outdoor heat exchanger 18 to release heat to the working fluid. The other path flows from port d into the fifth expansion valve 14 for throttling, cooling, and depressurization. At this time, the heat exchange device of motor and electrical control equipment 21 replaces the outdoor heat exchanger 18 to release heat to the working fluid. After passing through ports d and b of the second diverter valve 4, ports c and b of the second four-way reversing valve 5, and gas-liquid separator 17, it returns to compressor 1.

[0093] The control methods for the simultaneous heating of the crew cabin and the utilization of waste heat from the battery, motor, and electronic control equipment include:

[0094] Using the air-side outlet temperature of the indoor heat exchanger 19 as the target variable and the speed of the compressor 1 as the control variable, a PID control method is used to adjust the speed of the compressor 1 so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value. That is, a PID regulation relationship is established between the speed of the compressor 1 and the air-side outlet temperature of the indoor heat exchanger 19.

[0095] Using the dryness of the working fluid at the outlet of the heat exchanger of battery 20 as the target quantity and the opening degree of the third expansion valve 12 as the control quantity, a PID control method is used to adjust the opening degree of the third expansion valve 12 so that the dryness of the working fluid at the outlet of the heat exchanger of battery 20 reaches the optimal dryness of the heat exchanger of battery 20. That is, a PID control relationship is established between the opening degree of the third expansion valve 12 and the dryness of the working fluid at the outlet of the heat exchanger of battery 20.

[0096] Using the dryness of the working fluid at the outlet of the heat exchanger of the motor and electronic control equipment 21 as the target quantity and the opening degree of the fifth expansion valve 14 as the control quantity, a PID control method is used to adjust the opening degree of the fifth expansion valve 14 so that the dryness of the working fluid at the outlet of the heat exchanger of the motor and electronic control equipment 21 reaches the optimal dryness of the heat exchanger outlet of the motor and electronic control equipment 21. That is, a PID control relationship is established between the opening degree of the fifth expansion valve 14 and the dryness of the working fluid at the outlet of the heat exchanger of the battery 20.

[0097] For example, let the air-side outlet temperature of the indoor heat exchanger 19 be T1, the discharge pressure of the compressor 1 be P, the dryness of the working fluid at the outlet of the heat exchange device of the battery 20 be x1, and the dryness of the outlet of the heat exchange device of the motor and electronic control equipment 21 be x2. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, and its acquisition method includes, but is not limited to, the empirical correlation method and the intelligent optimization control method; x1 and x2 are the empirical optimal dryness of the outlet of the battery and motor heat exchange devices.

[0098] Figure 12 A schematic diagram illustrating the working principle of the simultaneous heating of the passenger compartment and battery preheating mode. Figure 12 As shown, when the system operates in the passenger compartment heating and battery preheating mode, ports a and c of the first four-way reversing valve 2 are connected, the seventh expansion valve 23 is open, and the first expansion valve 10 is open; ports a and c of the first three-way valve 6 are connected; ports a and c of the first diverter valve 3 are connected, the third expansion valve 12 is open, and the fourth expansion valve 13 is in a throttling state; ports c and b of the second diverter valve 4 are connected, ports c and b of the second four-way reversing valve 5 are connected; ports a and c of the fourth three-way valve 9 are connected, ports a and d of the second four-way reversing valve 5 are connected, and ports c and b of the third three-way valve 8 are connected. After being compressed by compressor 1, CO2 working fluid flows into indoor heat exchanger 19 and indoor secondary heat exchanger 22 through ports a and c of the first four-way reversing valve 2 to achieve the heating function of the passenger compartment. Then it flows into the first expansion valve 10, ports a and c of the first three-way valve 6, ports a and c of the first diversion valve 3, and the third expansion valve 12. At this time, the working fluid transfers heat to the heat exchange device of battery 20 to achieve the preheating function of battery 20. Then it flows back to compressor 1 through ports c and b of the second diversion valve 4, ports c and b of the second four-way reversing valve 5, and gas-liquid separator 17.

[0099] The control methods for the simultaneous crew cabin heating and battery preheating mode include:

[0100] Using the air-side outlet temperature of the indoor heat exchanger 19 as the target variable and the speed of the compressor 1 as the control variable, a PID control method is used to adjust the speed of the compressor 1 so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value. That is, a PID regulation relationship is established between the speed of the compressor 1 and the air-side outlet temperature of the indoor heat exchanger 19.

[0101] With the dryness of the working fluid at the outlet of the heat exchanger of battery 20 as the target quantity and the opening degree of the fourth expansion valve 13 as the control quantity, a PID control method is used to adjust the opening degree of the fourth expansion valve 13 so that the dryness of the working fluid at the outlet of the heat exchanger of battery 20 reaches the optimal dryness of the heat exchanger of battery 20. That is, a PID control relationship is established between the opening degree of the fourth expansion valve 13 and the dryness of the working fluid at the outlet of the heat exchanger of battery 20.

[0102] In the simultaneous heating and battery preheating mode of the crew cabin, the heat exchange device of battery 20 is connected in series with the indoor heat exchanger 19, which can ensure that the CO2 working fluid entering the heat exchange device of battery 20 is in a state of low dryness, thereby improving the temperature uniformity during the battery heat exchange process.

[0103] For example, let T1 be the air-side outlet temperature of the indoor heat exchanger 19, P be the exhaust pressure of the compressor 1, and x1 be the dryness of the working fluid at the outlet of the heat exchange device of the battery 20. T1 is the air supply temperature set by the car manufacturer according to different needs; P is the optimal pressure under the current operating conditions, which can be obtained by methods including but not limited to empirical correlation methods and intelligent optimization control methods; x1 is the empirical optimal dryness of the outlet of the heat exchange device of the battery 20.

[0104] Figure 13 This is a schematic diagram illustrating the working principle of the defogging and dehumidification mode. Figure 13 As shown, when the system is in defogging and dehumidification mode, port a and port c of the first four-way reversing valve 2 are connected, the seventh expansion valve 23 is in a throttling state, and the first expansion valve 10 is in an open state; port a and port b of the first three-way valve 6 are connected, port a and port c of the second three-way valve 7 are connected, the second expansion valve 11 is in an open state, port b and port a of the fourth three-way valve 9 are connected; port b and port c of the third three-way valve 8 are connected, and port d and port b of the second four-way reversing valve 5 are connected. After being compressed by compressor 1, CO2 working fluid flows into indoor heat exchanger 19 through ports a and c of the first four-way reversing valve 2. The air is heated, de-misted, and dehumidified. After being throttled, cooled, and depressurized by the seventh expansion valve 23, the air enters indoor secondary heat exchanger 22, achieving the function of de-misting and dehumidifying the air. After passing through ports a and b of the first expansion valve 10, the first three-way valve 6, the second three-way valve 7, the second expansion valve 11, the fourth three-way valve 9, the third three-way valve 8, the second four-way reversing valve 5, and the gas-liquid separator 17, it flows back to compressor 1.

[0105] The control methods for the defogging and dehumidification mode include:

[0106] Using the air-side outlet temperature of the indoor heat exchanger 19 as the target variable and the speed of the compressor 1 as the control variable, a PID control method is used to adjust the speed of the compressor 1 so that the air-side outlet temperature of the indoor heat exchanger 19 reaches the set value. That is, a PID regulation relationship is established between the speed of the compressor 1 and the air-side outlet temperature of the indoor heat exchanger 19.

[0107] Using the working fluid inlet temperature of the indoor secondary heat exchanger 22 as the target variable and the opening degree of the seventh expansion valve 23 as the control variable, a PID control method is used to adjust the opening degree of the seventh expansion valve 23 so that the working fluid inlet temperature of the indoor secondary heat exchanger 22 reaches the set value. That is, a PID control relationship is established between the opening degree of the seventh expansion valve 23 and the working fluid inlet temperature of the indoor secondary heat exchanger 22.

[0108] For example, the air-side outlet temperature of the indoor heat exchanger 19 is denoted as T1, and the working fluid-side inlet temperature of the indoor secondary heat exchanger 22 is denoted as T4.

[0109] The direct cooling and heating technology has the advantage of compact structure. At the same time, it can use CO2 working fluid to directly exchange heat with the battery, which can improve heat exchange efficiency, facilitate energy distribution control, and improve the response speed of thermal management.

[0110] The temperature uniformity of the battery can be improved by controlling the CO2 working fluid entering the battery heat exchanger to operate in a subcritical cycle.

[0111] Integrated management of vehicle heat can improve energy utilization efficiency under different operating modes.

[0112] This invention can solve the technical problems of large energy loss and slow response speed in the secondary circuit structure; this invention can solve the problem of uneven battery temperature in the battery heating mode; this invention can independently or simultaneously control the temperature of the passenger compartment, battery and motor during driving, and can use the waste heat of motor and other electronic control equipment to heat the passenger compartment and battery through the working fluid; its multiple operating modes can improve the energy utilization efficiency of the system under different operating conditions and reduce energy consumption across the entire operating range.

[0113] This invention discloses a carbon dioxide heat pump direct cooling / direct heating integrated thermal management system for electric vehicles, capable of switching between multiple modes. In passenger compartment cooling mode, it can dissipate heat for the battery and motor control equipment individually or simultaneously. When passenger compartment heating is not required, the system can still dissipate heat for either the battery or the motor control equipment independently. In passenger compartment heating mode, the system can recover and utilize heat from the battery and motor control equipment individually or simultaneously to heat the passenger compartment; under winter start-up conditions, the system can preheat the battery, mitigating the reduced driving range caused by low initial battery temperature. Furthermore, in preheating mode, the battery heat exchange device is connected in series with the interior heat exchanger, and by controlling the CO2 working fluid entering the battery heat exchange device to operate in a subcritical cycle, the temperature uniformity during battery heat exchange is improved, thereby enhancing heat exchange performance.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles, characterized in that, The system includes: a compressor (1), a first four-way reversing valve (2), a first flow divider valve (3), a second flow divider valve (4), a second four-way reversing valve (5), a first three-way valve (6), a second three-way valve (7), a third three-way valve (8), a fourth three-way valve (9), a first expansion valve (10), a second expansion valve (11), a third expansion valve (12), a fourth expansion valve (13), a fifth expansion valve (14), a sixth expansion valve (15), a regenerator (16), a gas-liquid separator (17), an outdoor heat exchanger (18), an indoor heat exchanger (19), a battery (20), a motor and electrical control equipment (21), an indoor secondary heat exchanger (22), and a seventh expansion valve (23); The a port of the first four-way reversing valve (2) is connected to the outlet of the compressor (1), the b port of the first four-way reversing valve (2) is connected to the a port of the second diverter valve (4), the c port of the first four-way reversing valve (2) is connected to the first vent of the indoor heat exchanger (19), and the d port of the first four-way reversing valve (2) is connected to the b port of the second three-way valve (7). The a port of the second three-way valve (7) is connected to the b port of the first three-way valve (6), and the c port of the second three-way valve (7) is connected to the first port of the second expansion valve (11); the second port of the second expansion valve (11) is connected to the b port of the fourth three-way valve (9), the a port of the fourth three-way valve (9) is connected to the first vent of the outdoor heat exchanger (18), and the c port of the fourth three-way valve (9) is connected to the a port of the second four-way reversing valve (5); the second vent of the outdoor heat exchanger (18) is connected to the b port of the third three-way valve (8), the a port of the third three-way valve (8) is connected to the b port of the first diverter valve (3) through the first heat exchange channel of the regenerator (16), and the c port of the third three-way valve (8) is connected to the d port of the second four-way reversing valve (5); the b port of the second four-way reversing valve (5) is connected to the inlet of the gas-liquid separator (17), and the outlet of the gas-liquid separator (17) is connected to the inlet of the compressor (1); The a port of the first three-way valve (6) is connected to the first port of the first expansion valve (10), and the c port of the first three-way valve (6) is connected to the a port of the first diverter valve (3); the second port of the first expansion valve (10) is connected to the first vent of the indoor secondary heat exchanger (22), the second vent of the indoor secondary heat exchanger (22) is connected to the first port of the seventh expansion valve (23), and the second port of the seventh expansion valve (23) is connected to the second vent of the indoor heat exchanger (19); The b port of the second diversion valve (4) is connected to the c port of the second four-way reversing valve (5) via the second heat exchange channel of the regenerator (16), the c port of the second diversion valve (4) is connected to the first port of the fourth expansion valve (13), and the d port of the second diversion valve (4) is connected to the first port of the sixth expansion valve (15). The c port of the first diversion valve (3) is connected to the first port of the third expansion valve (12), and the d port of the first diversion valve (3) is connected to the first port of the fifth expansion valve (14). The second port of the third expansion valve (12) is connected to the inlet of the heat exchange device of the battery (20), the second port of the fourth expansion valve (13) is connected to the outlet of the heat exchange device of the battery (20), the second port of the fifth expansion valve (14) is connected to the inlet of the heat exchange device of the motor control equipment (21), and the second port of the sixth expansion valve (15) is connected to the outlet of the heat exchange device of the motor control equipment (21). The system's operating modes include: passenger cabin cooling only, passenger cabin cooling and battery cooling simultaneously, passenger cabin cooling and motor / control equipment cooling simultaneously, passenger cabin cooling and battery / motor / control equipment cooling simultaneously, battery cooling only, motor / control equipment cooling only, passenger cabin heating only, passenger cabin heating and battery waste heat utilization simultaneously, passenger cabin heating and motor / control equipment waste heat utilization simultaneously, passenger cabin heating and battery preheating simultaneously, and defogging / dehumidification mode.

2. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the occupant cabin cooling mode only, the a port of the first four-way reversing valve (2) is connected to the d port; the b port of the second three-way valve (7) is connected to the c port; the second expansion valve (11) is open; the b port of the fourth three-way valve (9) is connected to the a port; the b port of the third three-way valve (8) is connected to the a port; the b port of the first diversion valve (3) is connected to the a port; the c port of the first three-way valve (6) is connected to the a port; the first expansion valve (10) is in a throttling state; the seventh expansion valve (23) is open; the c port of the first four-way reversing valve (2) is connected to the b port; the a port of the second diversion valve (4) is connected to the b port; and the c port of the second four-way reversing valve (5) is connected to the b port. The control method for the crew-only cabin cooling mode includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the first expansion valve (10) as the control quantity, the opening degree of the first expansion valve (10) is adjusted by PID control method so that the discharge pressure of the compressor (1) reaches the optimal pressure setting value under the current working condition.

3. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the same mode as the passenger cabin cooling and battery cooling, the a port of the first four-way reversing valve (2) is connected to the d port, and the b port of the second three-way valve (7) is connected to the c port; the second expansion valve (11) is open, the b port of the fourth three-way valve (9) is connected to the a port, and the b port of the third three-way valve (8) is connected to the a port; the b port of the first diverter valve (3) is connected to the a port and the c port respectively; the third expansion valve (12) is in a throttling state, and the fourth expansion valve (13) is in an open state; the c port of the first three-way valve (6) is connected to the a port, the first expansion valve (10) is in a throttling state, the seventh expansion valve (23) is in an open state, the c port of the first four-way reversing valve (2) is connected to the b port, the a port, c port of the second diverter valve (4) is connected to the b port, and the c port of the second four-way reversing valve (5) is connected to the b port; The control method for the simultaneous cooling of the crew cabin and battery cooling mode includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the first expansion valve (10) as the control quantity, the opening degree of the first expansion valve (10) is adjusted by PID control method so that the discharge pressure of the compressor (1) reaches the optimal pressure under the current working condition. With the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) as the target quantity and the opening degree of the third expansion valve (12) as the control quantity, the opening degree of the third expansion valve (12) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) reaches the optimal dryness of the outlet of the heat exchange device of the battery (20).

4. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the mode of refrigerating the passenger cabin while simultaneously cooling the motor and electronic control equipment, the a port and d port of the first four-way reversing valve (2) are connected; the b port and c port of the second three-way valve (7) are connected; the second expansion valve (11) is open; the b port and a port of the fourth three-way valve (9) are connected; the b port and a port of the third three-way valve (8) are connected; the b port of the first diverter valve (3) is connected to the a port and d port; the fifth expansion valve (14) is in a throttling state; the sixth expansion valve (15) is in an open state; the c port and a port of the first three-way valve (6) are connected; the first expansion valve (10) is in a throttling state; the seventh expansion valve (23) is in an open state; the c port and b port of the first four-way reversing valve (2) are connected; the a port and d port of the second diverter valve (4) are connected; and the c port and b port of the second four-way reversing valve (5) are connected. The control method for the simultaneous cooling mode of the crew cabin and the motor and electronic control equipment includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the first expansion valve (10) as the control quantity, the opening degree of the first expansion valve (10) is adjusted by PID control method so that the discharge pressure of the compressor (1) reaches the optimal pressure under the current working condition. With the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) as the target quantity and the opening degree of the fifth expansion valve (14) as the control quantity, the opening degree of the fifth expansion valve (14) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) reaches the optimal dryness of the outlet of the heat exchange device of the motor control equipment (21).

5. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the mode of refrigerating the passenger cabin while simultaneously cooling the battery, motor, and electronic control equipment, the a port of the first four-way reversing valve (2) is connected to the d port; the b port of the second three-way valve (7) is connected to the c port; the second expansion valve (11) is open; the b port of the fourth three-way valve (9) is connected to the a port; the b port of the third three-way valve (8) is connected to the a port; the b port of the first diverter valve (3) is connected to the a, d, and c ports; the fifth expansion valve (14) is in a throttling state; and the sixth... Expansion valve (15) is in the open state; third expansion valve (12) is in the throttling state; fourth expansion valve (13) is in the open state; port c of first three-way valve (6) is connected to port a; first expansion valve (10) is in the throttling state; seventh expansion valve (23) is in the open state; port c of first four-way directional valve (2) is connected to port b; ports a, d, and c of second diverter valve (4) are connected to port b; port c of second four-way directional valve (5) is connected to port d. The control method for the simultaneous cooling mode of the crew cabin, battery, motor, and electronic control equipment includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the first expansion valve (10) as the control quantity, the opening degree of the first expansion valve (10) is adjusted by PID control method so that the discharge pressure of the compressor (1) reaches the optimal pressure under the current working condition. With the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) as the target quantity and the opening degree of the third expansion valve (12) as the control quantity, the opening degree of the third expansion valve (12) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) reaches the optimal dryness of the outlet of the heat exchange device of the battery (20). With the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) as the target quantity and the opening degree of the fifth expansion valve (14) as the control quantity, the opening degree of the fifth expansion valve (14) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) reaches the optimal dryness of the outlet of the heat exchange device of the motor control equipment (21).

6. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system is in battery-only cooling mode, port a and port d of the first four-way reversing valve (2) are connected; port b and port c of the second three-way valve (7) are connected; the second expansion valve (11) is open; port b and port a of the fourth three-way valve (9) are connected; port b and port a of the third three-way valve (8) are connected; port b and port c of the first diverter valve (3) are connected; the third expansion valve (12) is in a throttling state; the fourth expansion valve (13) is in an open state; port c and port b of the second diverter valve (4) are connected; port c and port b of the second four-way reversing valve (5) are connected. The control method for the battery-only cooling mode includes: When the temperature of the battery (20) rises to the set temperature, the compressor (1) is activated; With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the third expansion valve (12) as the control quantity, the opening degree of the third expansion valve (12) is adjusted by PID control method so that the discharge pressure of the compressor (1) reaches the optimal pressure under the current working condition.

7. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the mode of cooling only the motor and electrical control equipment, the a port and d port of the first four-way reversing valve (2) are connected; the b port and c port of the second three-way valve (7) are connected; the second expansion valve (11) is open; the b port and a port of the fourth three-way valve (9) are connected; the b port and a port of the third three-way valve (8) are connected; the b port and d port of the first diverter valve (3) are connected; the fifth expansion valve (14) is in a throttling state; the sixth expansion valve (15) is in an open state; the d port and b port of the second diverter valve (4) are connected; and the c port and b port of the second four-way reversing valve (5) are connected. The control method for the cooling mode of the motor-only electronic control equipment includes: When the temperature of the motor control equipment (21) rises to the set temperature, the compressor (1) is run; With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the fifth expansion valve (14) as the control quantity, the PID control method is used to adjust the opening degree of the fifth expansion valve (14) so ​​that the discharge pressure of the compressor (1) reaches the optimal pressure under the current working conditions.

8. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the crew cabin heating mode only, port a and port c of the first four-way reversing valve (2) are connected, the seventh expansion valve (23) is in the open state, the first expansion valve (10) is in the open state, port a and port b of the first three-way valve (6) are connected, port a and port c of the second three-way valve (7) are connected, the second expansion valve (11) is in the throttling state, port b and port a of the fourth three-way valve (9) are connected; port b and port c of the third three-way valve (8) are connected, and port d and port b of the second four-way reversing valve (5) are connected. The control method for the crew-only cabin heating mode includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the discharge pressure of the compressor (1) as the target quantity and the opening degree of the second expansion valve (11) as the control quantity, the opening degree of the second expansion valve (11) is adjusted by PID control method so that the discharge pressure of the compressor (1) reaches the optimal pressure under the current working condition.

9. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the mode of crew cabin heating and battery waste heat utilization, port a and port c of the first four-way reversing valve (2) are connected, the seventh expansion valve (23) is in the open state, and the first expansion valve (10) is in the open state; port a and port c of the first three-way valve (6) are connected, port a and port c of the first diversion valve (3) are connected, the third expansion valve (12) is in the throttling state, the fourth expansion valve (13) is in the open state, port c and port b of the second diversion valve (4) are connected, and port c and port b of the second four-way reversing valve (5) are connected. The control method for the simultaneous crew cabin heating and battery waste heat utilization mode includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) as the target quantity and the opening degree of the third expansion valve (12) as the control quantity, the opening degree of the third expansion valve (12) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) reaches the optimal dryness of the outlet of the heat exchange device of the battery (20).

10. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the mode of heating the crew cabin while utilizing the waste heat of the motor and electrical control equipment, the a port and c port of the first four-way reversing valve (2) are connected, the seventh expansion valve (23) is in the open state, and the first expansion valve (10) is in the open state; the a port and c port of the first three-way valve (6) are connected, the a port and d port of the first diversion valve (3) are connected, the fifth expansion valve (14) is in the throttling state, the sixth expansion valve (15) is in the open state, the d port and b port of the second diversion valve (4) are connected, and the c port and b port of the second four-way reversing valve (5) are connected. The control method for the simultaneous heating of the crew cabin and the waste heat utilization mode of the motor and electronic control equipment includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) as the target quantity and the opening degree of the fifth expansion valve (14) as the control quantity, the opening degree of the fifth expansion valve (14) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) reaches the optimal dryness of the outlet of the heat exchange device of the motor control equipment (21).

11. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the mode of heating the passenger compartment while utilizing the waste heat of the battery, motor, and electronic control equipment, the a port and c port of the first four-way reversing valve (2) are connected, the seventh expansion valve (23) is in the open state, the first expansion valve (10) is in the open state; the a port and c port of the first three-way valve (6) are connected; the a port, c port, and d port of the first diverter valve (3) are connected, the third expansion valve (12) is in the throttling state, the fourth expansion valve (13) is in the open state; the fifth expansion valve (14) is in the throttling state, the sixth expansion valve (15) is in the open state; the d port, c port, and b port of the second diverter valve (4) are connected, and the c port and b port of the second four-way reversing valve (5) are connected. The control method for the simultaneous heating of the crew cabin and utilization of waste heat from the battery, motor, and electronic control equipment includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) as the target quantity and the opening degree of the third expansion valve (12) as the control quantity, the opening degree of the third expansion valve (12) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) reaches the optimal dryness of the outlet of the heat exchange device of the battery (20). With the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) as the target quantity and the opening degree of the fifth expansion valve (14) as the control quantity, the opening degree of the fifth expansion valve (14) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the motor control equipment (21) reaches the optimal dryness of the outlet of the heat exchange device of the motor control equipment (21).

12. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system operates in the passenger compartment heating and battery preheating mode, the a port and c port of the first four-way reversing valve (2) are connected, the seventh expansion valve (23) is in the open state, the first expansion valve (10) is in the open state; the a port and c port of the first three-way valve (6) are connected; the a port and c port of the first diverter valve (3) are connected, the third expansion valve (12) is in the open state, the fourth expansion valve (13) is in the throttling state; the c port and b port of the second diverter valve (4) are connected, the c port and b port of the second four-way reversing valve (5) are connected; the a port and c port of the fourth three-way valve (9) are connected, the a port and d port of the second four-way reversing valve (5) are connected, and the c port and b port of the third three-way valve (8) are connected. The control method for the simultaneous crew cabin heating and battery preheating mode includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. With the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) as the target quantity and the opening degree of the fourth expansion valve (13) as the control quantity, the opening degree of the fourth expansion valve (13) is adjusted by PID control method so that the dryness of the working fluid at the outlet of the heat exchange device of the battery (20) reaches the optimal dryness of the outlet of the heat exchange device of the battery (20).

13. The carbon dioxide heat pump direct cooling and direct heating integrated thermal management system for electric vehicles according to claim 1, characterized in that, When the system is in defogging and dehumidification mode, port a and port c of the first four-way reversing valve (2) are connected, the seventh expansion valve (23) is in a throttling state, and the first expansion valve (10) is in an open state; port a and port b of the first three-way valve (6) are connected, port a and port c of the second three-way valve (7) are connected, the second expansion valve (11) is in an open state, port b and port a of the fourth three-way valve (9) are connected; port b and port c of the third three-way valve (8) are connected, and port d and port b of the second four-way reversing valve (5) are connected. The control method for the defogging and dehumidification mode includes: With the air-side outlet temperature of the indoor heat exchanger (19) as the target quantity and the speed of the compressor (1) as the control quantity, the speed of the compressor (1) is adjusted by PID control method so that the air-side outlet temperature of the indoor heat exchanger (19) reaches the set value of the air-side outlet temperature of the indoor heat exchanger. Using the working fluid inlet temperature of the indoor secondary heat exchanger (22) as the target quantity and the opening degree of the seventh expansion valve (23) as the control quantity, the opening degree of the seventh expansion valve (23) is adjusted by PID control method so that the working fluid inlet temperature of the indoor secondary heat exchanger (22) reaches the set value of the working fluid inlet temperature of the indoor secondary heat exchanger (22).

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