Low-temperature operation control method for heat pump system

Abstract

The present invention provides a low-temperature operation control method for a heat pump system in the technical field of electric vehicle heat pump air-conditioning systems, including Control Method 1 and Control Method 2. Method 1: The heat pump system includes a driving unit, namely an electric control driving unit and a motor driving unit, which heat the coolant. The coolant heats the refrigerant to change the working pressure on the low-pressure side of the refrigeration cycle, increase the working temperature and pressure on the high-pressure side of the refrigeration cycle, and increase the heating capacity. Method 2: The heat pump system further includes an air-conditioning box temperature air damper and an evaporator. The change in the opening degree of the air-conditioning box temperature air damper corresponds to the change in the incoming air temperature in the evaporator. The change in the incoming air temperature is used to change the temperature and pressure state of the refrigerant in the evaporator, increase the working temperature and pressure on the high-pressure side of the refrigeration cycle, and increase the heating capacity. The two control methods involved in the present invention can effectively improve the low-temperature operation performance of the heat pump air-conditioning system, improve the comfort of the passenger compartment, and meet the requirements of the vehicle for low-temperature defrosting without changing the hardware structure.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle heat pump air conditioning systems, and specifically, to a low-temperature operation control method for a heat pump system. Background Art

[0002] The heat pump air conditioning system has become an important part of the electric vehicle thermal management system and an important development direction of the electric vehicle thermal management system technology. However, due to the physical properties of current mainstream refrigerants (R134a and R1234yf), when the ambient temperature reaches -20°C or even lower, the heat pump system cannot absorb heat from the ambient air.

[0003] After searching the prior art, it is found that the Chinese invention patent publication number is CN202420020U, which discloses an automotive heat pump air conditioning system. The refrigerant outlet of the compressor is connected to the liquid inlet of the outdoor unit assembly through the condenser core, the valve part of the heating expansion valve, and the first electromagnetic cut-off valve. The refrigerant outlet is also connected to the liquid inlet of the outdoor unit assembly through the third electromagnetic cut-off valve. The liquid outlet of the outdoor unit assembly is connected to the refrigerant inlet of the compressor through the second cut-off valve, the valve part of the refrigeration expansion valve, the evaporator core, and the temperature sensing part of the refrigeration expansion valve. The liquid outlet of the outdoor unit assembly is also connected to the temperature sensing part of the heating expansion valve and the refrigerant inlet of the compressor through the fourth electromagnetic cut-off valve. The condenser core and the evaporator core are located between the blower motor and the air door. This invention has the problems that when the ambient temperature reaches -20°C or even lower, the heat pump system cannot absorb heat from the ambient air, the air outlet temperature of the air conditioning box is not high enough, the comfort of the passenger compartment cannot be improved, and the low-temperature defrosting requirement of the whole vehicle cannot be met. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a low-temperature operation control method for a heat pump system.

[0005] According to a low-temperature operation control method for a heat pump system provided by the present invention, it includes an air conditioning system, and the air conditioning system includes a compressor, a first heat exchanger, an evaporator, a gas-liquid separator, a cut-off valve, and an in-vehicle condenser.

[0006] The outlet of the gas-liquid separator is connected to the inlet of the compressor through a pipeline. A three-way valve is arranged on one side of the outlet of the compressor. The outlet of the compressor is connected to the inlet of the in-vehicle condenser and the inlet of the first heat exchanger through the refrigerant three-way valve. And a temperature sensor for the air outlet of the air conditioning box is arranged on one side of the inlet of the in-vehicle condenser.

[0007] A first throttle valve is provided on the outlet side of the first heat exchanger. The outlet of the first heat exchanger is connected to the inlet of the evaporator through the first throttle valve. And a check valve is provided on the outlet side of the in-vehicle condenser. The outlet of the in-vehicle condenser is connected to the inlet of the evaporator through the check valve and the first throttle valve;

[0008] The inlet of the gas-liquid separator is connected to the outlet of the evaporator through a pipeline. The inlet of the stop valve is connected to the pipeline between the first heat exchanger and the refrigerant three-way valve. And the inlet of the gas-liquid separator is connected to the outlet of the stop valve through a pipeline;

[0009] The outlet of the gas-liquid separator is connected to the inlet of the compressor through a pipeline. And a compressor inlet pressure sensor is provided on the pipeline on the inlet side of the compressor.

[0010] A low-temperature operation control method is applied to the heat pump system described above, including Control Method 1 and Control Method 2;

[0011] When the gas enters the compressor from the gas-liquid separator and becomes a high-temperature and high-pressure gas, the high-temperature and high-pressure gas enters the in-vehicle condenser through the three-way valve and then becomes a medium-temperature and high-pressure liquid. The medium-temperature and high-pressure liquid sequentially passes through the check valve and the first throttle valve and becomes a low-temperature and low-pressure gas-liquid two-phase mixture. The low-temperature and low-pressure gas-liquid two-phase mixture becomes a low-temperature and low-pressure gas through the first heat exchanger. The low-temperature and low-pressure gas enters the gas-liquid separator through the stop valve, and the heat release of the in-vehicle condenser realizes the heating effect. At this time, the pipeline of the refrigerant three-way valve leading to the first heat exchanger is in a closed state;

[0012] Control Method 1: The heat pump system includes a driving unit. The driving unit includes an electric control driving unit and a motor driving unit. The electric control driving unit and the motor driving unit heat the refrigerant to change the gas working pressure on the low-pressure side of the refrigeration cycle, increase the gas working temperature and pressure on the high-pressure side of the refrigeration cycle, and increase the heating capacity;

[0013] Control Method 2: The heat pump system further includes an air-conditioning box temperature air damper and an evaporator. The change in the opening degree of the air-conditioning box temperature air damper corresponds to the change in the incoming air temperature in the evaporator. The change in the incoming air temperature is used to change the temperature and pressure state of the refrigerant in the evaporator, increase the gas working temperature and pressure on the high-pressure side of the refrigeration cycle, and increase the heating capacity;

[0014] Control Method 1 and Control Method 2 are applied simultaneously or separately.

[0015] In some embodiments, the air-conditioning system further includes a first fan, and the first fan is provided on one side of the evaporator.

[0016] In some embodiments, a coolant circuit system is further included. The coolant circuit system includes a first water pump, a radiator, and the drive unit. The first water pump, the radiator, and the drive unit are sequentially connected to the first heat exchanger through pipelines.

[0017] In some embodiments, the coolant circuit system further includes a first expansion water tank. The inlet of the first expansion water tank is connected to the outlet of the first heat exchanger, and the outlet of the first expansion water tank is connected to the inlet of the first water pump.

[0018] In some embodiments, the coolant circuit system further includes a second fan, and the second fan is disposed on one side of the radiator.

[0019] In some embodiments, a battery temperature control system is further included. The battery temperature control system includes a second water pump, an electric heater, and a battery. The air conditioning system further includes a third throttle valve and a second heat exchanger. The second heat exchanger, the electric heater, the first water pump, and the battery are connected to each other through pipelines. The inlet of the second heat exchanger is connected to the first heat exchanger through the third throttle valve, and the outlet of the second heat exchanger is connected to the inlet of the gas-liquid separator.

[0020] In some embodiments, the battery temperature control system further includes a second expansion water tank. The inlet of the second expansion water tank is connected to the outlet of the battery, and the outlet of the second expansion water tank is connected to the inlet of the second water pump.

[0021] A vehicle, characterized in that the heat pump system described above is adopted.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. By setting an electric control drive unit and a motor drive unit to heat the coolant, and the coolant heats the refrigerant, the temperature and pressure state of the refrigerant on the low-pressure side in the refrigerant cycle can be changed, thereby increasing the temperature and pressure of the compressor exhaust and increasing the air outlet temperature of the air conditioning box.

[0024] 2. By setting a temperature air door in the air conditioning box, by changing the opening degree of the internal and external circulation air doors of the air conditioning box, the air temperature passing through the evaporator is correspondingly changed, reducing the influence of the temperature in a low-temperature environment on the temperature and pressure state of the refrigerant on the low-pressure side in the refrigeration cycle, thereby increasing the temperature and pressure of the compressor exhaust and increasing the air outlet temperature of the air conditioning box.

[0025] 3. The two control methods involved in the present invention can effectively improve the low-temperature operation performance of the heat pump air-conditioning system, enhance the comfort of the passenger compartment, and meet the requirements of vehicle low-temperature defrosting without changing the hardware structure. At the same time, there is basically no coupling between the two control methods, and they can be used alone or simultaneously. The control logic is simple and reliable, and the anti-interference ability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 Schematic diagram of the heat management system circuit corresponding to the low-temperature operation control method of the heat pump system of the present invention;

[0028] Figure 2 Schematic diagram of the water-source heat pump working in a low-temperature environment for the low-temperature operation control method of the heat pump system of the present invention;

[0029] Figure 3 Schematic diagram of the first control method logic of the low-temperature operation control method of the heat pump system of the present invention;

[0030] Figure 4 Schematic diagram of the second control method logic of the low-temperature operation control method of the heat pump system of the present invention.

[0031] REFERENCE SIGNS:

[0032] Compressor 1, Cut-off valve 10, First expansion water kettle 19

[0033] Refrigerant three-way valve 2, In-vehicle condenser 11, Second fan 20

[0034] First heat exchanger 3, Check valve 12, Second water pump 21

[0035] First throttle valve 4, First fan 13, Electric heater 22

[0036] Second throttle valve 5, Air-conditioning box temperature air damper 14, Battery 23

[0037] Evaporator 6, First water pump 15, Second expansion water kettle 24

[0038] Third throttle valve 7, Radiator 16, Compressor inlet pressure sensor 25

[0039] Second heat exchanger 8, Electric control drive unit 17, Air-conditioning box outlet air temperature sensor 26

[0040] Gas-liquid separator 9, Motor drive unit 18 DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] As Figure 3 shown, when the thermal management control system enters the water source heat pump mode, the first control method will be triggered to start; first, it is detected whether the current ambient temperature Tambient is less than or equal to the set temperature Tset; if it is determined to be yes, then it is judged whether the compressor suction pressure PcomIN is less than or equal to the set pressure Pset; if it is determined to be yes, the motor electronic control unit is started to heat the coolant. The heating power is the control variable, and the target variable is the absolute value of the difference between the compressor suction pressure PcomIN and the set pressure Pset.

[0043] As Figure 4 shown, when the thermal management control system enters the water source heat pump mode, the second control method will be triggered to start; first, it is detected whether the current ambient temperature Tambient is less than or equal to the set temperature Tset; if it is determined to be yes, then the opening position of the inside and outside circulation air damper of the current air handling unit is judged, simply referred to as the opening; if the opening is less than the set value, the opening is adjusted. The control variable is the air damper opening, the first target variable is the absolute value of the difference between the air handling unit outlet air temperature Toutlet and the set value Trec.set; the second target variable is the vehicle interior humidity.

[0044] Embodiment 1

[0045] When a vehicle using the low-temperature operation control method of the pump system of the present invention starts in a low-temperature environment, the heat pump air-conditioning system cannot absorb heat from the environment, and the water source heat pump operation mode needs to be started. At this time, the electric heater 22 is turned on to heat the coolant flowing through the second heat exchanger 8. In the second heat exchanger 8, the coolant exchanges heat with the refrigerant, and then the refrigerant is pumped into the vehicle interior condenser 11 through the compressor 1, thereby heating the occupant compartment environment. Since the first heat exchanger 3 is in the low-temperature environment of the front vehicle compartment of the vehicle. This low-temperature environment will limit the refrigerant saturation pressure of the first heat exchanger 3. Since this temperature and pressure are lower than the normal pressure and temperature required for system operation. At this time, the first heat exchanger 3 will retain more refrigerant, which not only restricts the increase of the system low pressure but also reduces the refrigerant flow rate that can participate in the cycle. By actively generating heat through the electric control drive unit 17 and the motor drive unit 18, the coolant flowing through the first heat exchanger 3 is heated, and then the refrigerant in the first heat exchanger 3 is heated to increase its corresponding saturation temperature and pressure. To ensure the safe operation of the system, when actively generating heat through the electric control drive unit 17 and the motor drive unit 18, the maximum coolant temperature needs to be set.

[0046] Example 2

[0047] When a vehicle adopting the low-temperature operation control method of the pump system of the present invention starts in a low-temperature environment, the heat pump air-conditioning system cannot absorb heat from the environment, and it is necessary to start the water-source heat pump operation mode. At this time, the electric heater 22 is turned on to heat the coolant flowing through the second heat exchanger 8. In the second heat exchanger 8, the coolant exchanges heat with the refrigerant, and then the refrigerant is pumped into the in-vehicle condenser 11 through the compressor 1 to heat the occupant compartment environment. Since the first heat exchanger 3 is in the low-temperature environment of the front compartment of the vehicle, this low-temperature environment will limit the refrigerant saturation pressure of the first heat exchanger 3. Since this temperature and pressure are lower than the normal pressure and temperature required for system operation, at this time, the first heat exchanger 3 will retain more refrigerant, which not only restricts the increase of the low pressure of the system but also reduces the refrigerant flow rate that can participate in the cycle. The waste heat generated by the normal operation of the electric control drive unit 17 and the motor drive unit 18 is used to heat the coolant flowing through the first heat exchanger 3, thereby heating the refrigerant in the first heat exchanger 3 and increasing its corresponding saturation temperature and pressure. To ensure the safe operation of the system, when heating the coolant with the waste heat of the electric control drive unit 17 and the motor drive unit 18, it is necessary to set the maximum coolant temperature. When the set maximum coolant temperature is exceeded, the excess heat can be discharged through the radiator 16.

[0048] Example 3

[0049] When a vehicle adopting the low-temperature operation control method of the pump system of the present invention starts or operates in a low-temperature environment, the low-temperature air entering the air-conditioning box from the outside will first pass through the evaporator 6. The evaporator 6 will retain a certain amount of refrigerant, and this low-temperature air will maintain the refrigerant pressure in the evaporator 6 at a relatively low level, thereby lowering the low-pressure side pressure of the entire refrigerant cycle. By adjusting the inside / outside circulation air damper of the air-conditioning box, the temperature in the vehicle compartment, which is higher than the outside low-temperature environment, is introduced again into the air flow passage of the evaporator 6 to increase the temperature of the refrigerant in the evaporator, thereby increasing the pressure of the refrigerant in the evaporator, changing the low-pressure side pressure of the refrigerant cycle, and increasing the overall heat exchange capacity of the heat pump air-conditioning system.

[0050] Example 4

[0051] When a vehicle adopting the low-temperature operation control method of the pump system of the present invention starts or operates in a low-temperature environment, the opening degree of the inside / outside circulation air damper of the air-conditioning box can be adjusted through two control objectives; the first control objective is the absolute value of the difference between the air outlet temperature Toutlet of the air-conditioning box and the set value Trec.set; the second control objective variable is the humidity inside the vehicle. The control system can adopt any one of these two control objectives.

[0052] Example 5

[0053] When a vehicle adopting the low-temperature operation control method of the pump system of the present invention starts or operates in a low-temperature environment, the adjustment range of the opening degree of the inside and outside circulation air dampers of the air-conditioning box will be adjusted within the preset maximum opening degree range.

[0054] Working principle:

[0055] The gaseous refrigerant is discharged from the compressor 1 and passes through the refrigerant three-way valve 2. At this time, the refrigerant three-way valve 2 opens the channel leading to the in-vehicle condenser 11 and closes the channel leading to the first heat exchanger 3. The refrigerant enters the in-vehicle condenser 11, exchanges heat with air when passing through the in-vehicle condenser 11, then passes through the check valve 12 and reaches the third throttle valve 7. At this time, the first throttle valve 4 and the second throttle valve 5 are in the closed state; after passing through the third throttle valve 7, it enters the second heat exchanger 8, and the refrigerant exchanges heat with the coolant in the second heat exchanger 8; then it enters the gas-liquid separator 9 and then enters the compressor to complete the cycle.

[0056] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0057] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A heat pump system, characterized in that, Comprising an air-conditioning system, the air-conditioning system including a compressor (1), a first heat exchanger (3), an evaporator (6), a gas-liquid separator (9), a stop valve (10), and an in-vehicle condenser (11); The outlet (9) of the gas-liquid separator is connected to the inlet (1) of the compressor through a pipeline. On one side of the outlet of the compressor (1), there is a refrigerant three-way valve (2). The outlet of the compressor (1) is connected to the inlet of the in-vehicle condenser (11) and the inlet of the first heat exchanger (3) through the refrigerant three-way valve (2). And on one side of the inlet of the in-vehicle condenser (11), there is an air-conditioning box outlet air temperature sensor (26); On one side of the outlet of the first heat exchanger (3), there is a first throttle valve (4). The outlet of the first heat exchanger (3) is connected to the inlet of the evaporator (6) through the first throttle valve (4). And on one side of the outlet of the in-vehicle condenser (11), there is a check valve (12). The outlet of the in-vehicle condenser (11) is connected to the inlet of the evaporator (6) through the check valve (12) and a second throttle valve (5); The inlet of the gas-liquid separator (9) is connected to the outlet of the evaporator (6) through a pipeline. The inlet of the stop valve (10) is connected to the pipeline between the first heat exchanger (3) and the refrigerant three-way valve (2). And the inlet of the gas-liquid separator (9) is connected to the outlet of the stop valve (10) through a pipeline; The outlet of the gas-liquid separator (9) is connected to the inlet of the compressor (1) through a pipeline. And on the pipeline on one side of the inlet of the compressor (1), there is a compressor inlet pressure sensor (25); The heat pump system further includes a coolant circuit system. The coolant circuit system includes a first water pump (15), a radiator (16), and a drive unit. The first water pump (15), the radiator (16), and the drive unit are sequentially connected to the first heat exchanger (3) through pipelines; The heat pump system includes a first control method and a second control method; When gas enters the compressor (1) from the gas-liquid separator (9) and becomes high-temperature and high-pressure gas, the high-temperature and high-pressure gas enters the in-vehicle condenser (11) through the three-way valve (2) and then becomes medium-temperature and high-pressure liquid. The medium-temperature and high-pressure liquid sequentially passes through the check valve (12) and the first throttle valve (4) and becomes a low-temperature and low-pressure gas-liquid two-phase mixture. The low-temperature and low-pressure gas-liquid two-phase mixture becomes low-temperature and low-pressure gas through the first heat exchanger (3). The low-temperature and low-pressure gas enters the gas-liquid separator (9) through the stop valve (10). The heat release of the in-vehicle condenser (11) realizes the heating effect. At this time, the pipeline of the refrigerant three-way valve (2) leading to the first heat exchanger (3) is in a closed state; The first control method: The heat pump system includes a driving unit, and the driving unit includes an electric control driving unit (17) and a motor driving unit (18). The electric control driving unit (17) and the motor driving unit (18) heat the refrigerant to change the gas working pressure on the low-pressure side of the refrigeration cycle, increase the gas working temperature and pressure on the high-pressure side of the refrigeration cycle, and increase the heating capacity. The second control method: The heat pump system further includes an air conditioning box temperature damper (14) and an evaporator (6). The change in the opening degree of the air conditioning box temperature damper (14) corresponds to the change in the incoming air temperature in the evaporator (6). The change in the incoming air temperature is used to change the temperature and pressure state of the refrigerant in the evaporator (6), increase the gas working temperature and pressure on the high-pressure side of the refrigeration cycle, and increase the heating capacity. The first control method and the second control method are applied simultaneously or separately.

2. The heat pump system according to claim 1, characterized in that, The air conditioning system further includes a first fan (13), and the first fan (13) is arranged on one side of the evaporator (6).

3. The heat pump system according to claim 1, characterized in that, The coolant circuit system further includes a first expansion water tank (19). The inlet of the first expansion water tank (19) is connected to the outlet of the first heat exchanger (3), and the outlet of the first expansion water tank (19) is connected to the inlet of the first water pump (15).

4. The heat pump system according to claim 1, characterized in that, The coolant circuit system further includes a second fan (20), and the second fan (20) is arranged on one side of the radiator (16).

5. The heat pump system according to claim 1, characterized in that, It further includes a battery temperature control system. The battery temperature control system includes a second water pump (21), an electric heater (22), and a battery (23). The air conditioning system further includes a third throttle valve (7) and a second heat exchanger (8). The second heat exchanger (8), the electric heater (22), the second water pump (21), and the battery (23) are connected to each other through pipelines. The inlet of the second heat exchanger (8) is connected to the first heat exchanger (3) through the third throttle valve (7), and the outlet of the second heat exchanger (8) is connected to the inlet of the gas-liquid separator (9).

6. The heat pump system according to claim 5, characterized in that, The battery temperature control system further includes a second expansion water tank (24). The inlet of the second expansion water tank (24) is connected to the outlet of the battery (23), and the outlet of the second expansion water tank (24) is connected to the inlet of the second water pump (21).

7. A vehicle, characterized in that, The heat pump system according to claim 1 is adopted.

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