Commercial vehicle thermal management system and control method thereof

Abstract

The invention discloses a commercial vehicle thermal management system and a control method thereof.The system comprises an electric control unit, an engine cooling loop, a hydraulic retarder cooling loop, a cooling loop on-off unit and a temperature detection unit, and the cooling loop on-off unit is used for connecting and disconnecting the hydraulic retarder cooling loop and the engine cooling loop and / or connecting and disconnecting the hydraulic retarder cooling loop and the engine cooling loop; the cooling loop on-off unit is used for bypassing a hydraulic retarder cooling loop; the temperature detection unit is used for detecting the environment temperature, the cooling liquid temperature and / or the cylinder cover temperature. The electric control unit controls the heat management valve, the electronic water pump, the electronic fan and the air inlet grid switch according to temperature signals. And the electric control unit controls the cooling loop on-off unit according to the working state of the hydraulic retarder so as to connect and disconnect the hydraulic retarder cooling loop and the engine cooling loop. Therefore, the engine and the hydraulic retarder share one set of cooling loop, and the cooling loop is switched on and off according to the working state of the hydraulic retarder, so that the vehicle has good heat dissipation performance.

Description

Technical Field

[0001] The present invention relates to the field of engine technology, and in particular to a commercial vehicle thermal management system and a control method thereof. Background Art

[0002] As transport companies and truck drivers gradually increase their requirements for cargo load and timeliness, the engine power of heavy trucks is becoming stronger and stronger. However, this leads to overload of truck service brakes. When friction brakes work for a long time, their temperature can reach up to 1000℃, which will cause a sharp decline in braking performance or even failure, thus threatening the driving safety of the vehicle.

[0003] The hydraulic retarder is an auxiliary braking system that can replace 90% of service brakes, thereby ensuring that the vehicle's brakes are in a cold state during long downhill slopes. When various emergency situations occur on the road, the main and auxiliary braking systems can work together to achieve maximum braking effect.

[0004] In view of the above situation, in the prior art, when using a hydraulic retarder, the engine speed must be maintained above 1500 rpm, otherwise the engine water circulation will slow down, which may easily lead to high temperature or overheating of the oil, and the braking effect of the hydraulic retarder may be reduced or even automatically exit. Summary of the invention

[0005] In view of the above-mentioned shortcomings, the technical problem to be solved by the present invention is to provide a commercial vehicle thermal management system and a control method thereof, so that the engine and the hydraulic retarder share a cooling circuit and are turned on and off according to the working state of the hydraulic retarder, so that the vehicle has good heat dissipation performance.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A commercial vehicle thermal management system, comprising an electronic control unit, an engine cooling circuit and a hydraulic retarder cooling circuit; the engine cooling circuit comprises an engine, a thermal management valve, a radiator, an electronic water pump and an electronic fan arranged behind the radiator, the thermal management valve, the electronic water pump and the electronic fan are respectively electrically connected to the electronic control unit; the hydraulic retarder cooling circuit comprises a heat exchanger; an air intake grid is arranged in front of the radiator; the system further comprises a cooling circuit on-off unit and a temperature detection unit, the cooling circuit on-off unit and the temperature detection unit are respectively electrically connected to the electronic control unit; the cooling circuit on-off unit The on-off unit is used for switching on and off the hydraulic retarder cooling circuit and the engine cooling circuit, and / or the cooling circuit on-off unit is used for bypassing the hydraulic retarder cooling circuit; the temperature detection unit is used for detecting the ambient temperature, the coolant temperature and / or the cylinder head temperature, and transmitting the corresponding temperature signal to the electronic control unit, and the electronic control unit controls the thermal management valve, the electronic water pump, the electronic fan and the intake grid switch according to the temperature signal; the electronic control unit controls the cooling circuit on-off unit according to the working state of the hydraulic retarder to switch on and off the hydraulic retarder cooling circuit and the engine cooling circuit.

[0008] Preferably, the cooling circuit on-off unit includes a first electric three-way valve, an inlet of the first electric three-way valve is connected to the outlet of the electronic water pump, one outlet of the first electric three-way valve is connected to the inlet of the engine, the other outlet of the first electric three-way valve is connected to the inlet of the heat exchanger, and the outlet of the heat exchanger is connected to the engine outlet.

[0009] Preferably, the cooling circuit on-off unit comprises a second electric three-way valve, and the second electric three-way valve is respectively connected to the inlet of the thermal management valve, the outlet of the engine and the outlet of the heat exchanger.

[0010] Preferably, the cooling circuit on-off unit comprises a bypass valve and a bypass pipeline, and the bypass valve is connected to the outlet of the heat exchanger.

[0011] Preferably, the temperature detection unit includes an ambient temperature sensor, a coolant temperature sensor and a cylinder head temperature sensor;

[0012] The ambient temperature sensor is used to detect the ambient temperature, and the electronic control unit controls the thermal management valve according to the coolant temperature;

[0013] The coolant temperature sensor is used to detect the coolant temperature at the engine outlet, and the electronic control unit controls the thermal management valve, the electronic fan and the intake grille switch according to the coolant temperature;

[0014] The cylinder head temperature sensor is used to detect the cylinder head temperature, and the electronic control unit controls the electronic water pump according to the cylinder head temperature.

[0015] A control method for a commercial vehicle thermal management system is applied to the above-mentioned commercial vehicle thermal management system, and the control method comprises the following steps:

[0016] Cooling circuit control: when the hydraulic retarder is not working, the cooling circuit on-off unit disconnects or bypasses the hydraulic retarder cooling circuit; when the hydraulic retarder is in working state, the cooling circuit on-off unit connects the engine cooling circuit and the hydraulic retarder circuit;

[0017] Thermal management valve control: when the coolant temperature is lower than the small cycle temperature, the thermal management valve is closed for small cycle cooling; when the coolant temperature is not lower than the small cycle temperature, the thermal management valve is opened for large cycle cooling, and the opening of the thermal management valve is PID controlled according to the coolant temperature and engine speed;

[0018] Electronic water pump control, according to the cylinder head temperature and engine power, obtains the corresponding water pump speed, and controls the electronic water pump in an open loop according to the water pump speed;

[0019] Electronic fan control: when the coolant temperature is lower than the preset temperature threshold, the electronic fan runs at a lower basic speed; when the coolant temperature is not lower than the preset temperature threshold, the corresponding fan speed is obtained according to the coolant temperature and engine power, and the electronic fan is controlled according to the fan speed;

[0020] Air inlet grille control: when the coolant temperature is lower than the preset temperature threshold, the air inlet grille is closed; when the coolant temperature is not lower than the preset temperature threshold, the air inlet grille is opened.

[0021] Preferably, the control method further includes: when the engine power suddenly increases and the duration exceeds a preset time, the air intake grille is opened in advance to cool the engine in advance; when the engine power suddenly increases, the electronic fan is turned on in advance; and / or; when the engine power suddenly increases, the thermal management valve is opened a certain degree in advance.

[0022] A preferred embodiment is that the control method further includes: when the electronic fan increases its speed, the electronic fan is used to adjust the coolant temperature at the engine outlet, and the thermal management valve does not operate; when the engine heating power is greater than the heat dissipation power when the thermal management valve is fully open and the electronic fan does not intervene, the thermal management valve is kept fully open in a large cycle, and the coolant temperature at the engine outlet is adjusted by the electronic fan; when the engine heating power is relatively small, the thermal management valve is used to adjust the coolant temperature at the engine outlet, and the electronic fan does not need to intervene.

[0023] Preferably, the thermal management valve control further includes: when the opening of the thermal management valve is PID controlled according to the coolant temperature and the engine speed, the optimal thermal management valve opening is obtained from different calibrated MAP tables according to the ambient temperature, coolant temperature and engine power.

[0024] Preferably, the control method further comprises: when the coolant temperature exceeds 99° C., a temperature alarm is triggered, the thermal management valve is fully opened in a large cycle, the electronic fan runs at full speed, and the electronic water pump runs at maximum power.

[0025] After adopting the above technical solution, the beneficial effects of the present invention are:

[0026] Due to the commercial vehicle thermal management system and control method thereof of the present invention, the system includes an electronic control unit, an engine cooling circuit and a hydraulic retarder cooling circuit, and also includes a cooling circuit on-off unit and a temperature detection unit, and the cooling circuit on-off unit and the temperature detection unit are respectively electrically connected to the electronic control; the cooling circuit on-off unit is used to switch on and off the hydraulic retarder cooling circuit and the engine cooling circuit, and / or, the cooling circuit on-off unit is used to bypass the hydraulic retarder cooling circuit; the temperature detection unit is used to detect the ambient temperature, the coolant temperature and / or the cylinder head temperature, and transmit the corresponding temperature signal to the electronic control unit, and the electronic control unit controls the thermal management valve, the electronic water pump, the electronic fan and the intake grid switch according to the temperature signal; the electronic control unit controls the cooling circuit on-off unit according to the working state of the hydraulic retarder to switch on and off the hydraulic retarder cooling circuit and the engine cooling circuit. When the hydraulic retarder is not working, the heat exchanger is not involved in the coolant cooling cycle by controlling the cooling circuit on-off unit. When the coolant temperature is low, the coolant returns to the electronic water pump inlet through the small circulation coolant pipeline, and the coolant does not dissipate heat through the radiator, so as to quickly increase the coolant temperature; when the coolant temperature rises and the thermal management valve is opened, the coolant passes through the large circulation pipeline and flows through the radiator to dissipate heat, so as to achieve temperature control of the engine; when the hydraulic retarder is working, the heat exchanger is involved in the coolant circulation by controlling the cooling circuit on-off unit to meet the heat dissipation needs of the hydraulic retarder. It can be seen that the present invention mainly allows the engine and the hydraulic retarder to share a set of cooling circuits, and switches on and off according to the working state of the hydraulic retarder, so that the vehicle has good heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a principle block diagram of the thermal management system of a commercial vehicle in the present invention;

[0028] In the figure: 100-engine cooling circuit, 10-engine, 11-thermal management valve, 12-radiator, 13-electronic fan, 14-electronic water pump, 15-expansion water tank, 16-first exhaust pipe, 17-second exhaust pipe, 18-return pipe, 200-hydraulic retarder cooling circuit, 20-heat exchanger, 30-first electric three-way valve, 31-second electric three-way valve, 4-motor. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0031] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Embodiment 1:

[0033] like Figure 1 As shown, a thermal management system for a commercial vehicle includes an electronic control unit, an engine cooling circuit 100 and a hydraulic retarder cooling circuit 200; wherein the engine cooling circuit 100 includes an engine 10, a thermal management valve 11, a radiator 12, an electronic water pump 14 and an electronic fan 13 arranged behind the radiator 12, and the thermal management valve 11, the electronic water pump 14 and the electronic fan 13 are electrically connected to the electronic control unit respectively; wherein the hydraulic retarder cooling circuit 200 includes a heat exchanger 20; and an air intake grid is arranged in front of the radiator 12; the thermal management system for a commercial vehicle of the present invention also includes a motor 4, which supplies power to the electronic fan 13, the electronic water pump 14 and the cooling circuit on-off unit, etc.

[0034] The commercial vehicle thermal management system of the present invention further includes a cooling circuit on-off unit and a temperature detection unit, which are electrically connected to the electronic control unit respectively; the cooling circuit on-off unit is used to switch on and off the hydraulic retarder cooling circuit 200 and the engine cooling circuit 100, and / or, the cooling circuit on-off unit is used to bypass the hydraulic retarder cooling circuit 200; the temperature detection unit is used to detect the ambient temperature, the coolant temperature and / or the cylinder head temperature, and transmit the corresponding temperature signal to the electronic control unit, and the electronic control unit controls the opening of the thermal management valve 11, the speed of the electronic water pump 14, the speed of the electronic fan 13 and the intake grid switch according to the temperature signal; at the same time, the electronic control unit also controls the cooling circuit on-off unit according to the working state of the hydraulic retarder to switch on and off the hydraulic retarder cooling circuit 200 and the engine cooling circuit 100.

[0035] like Figure 1 As shown, the present invention mainly enables the hydraulic retarder and the engine 10 to share a cooling circuit. When the hydraulic retarder is not working, the electronic control unit controls the cooling circuit on-off unit to operate to disconnect the engine cooling circuit 100 and the hydraulic retarder cooling circuit 200, so that the heat exchanger 20 does not participate in the circulation of the coolant. At this time, the large circulation and small circulation in the engine cooling circuit 100 are completely consistent with those of the vehicle without hydraulic retarder.

[0036] At this time, when the coolant temperature detected by the temperature detection unit is lower than the preset small circulation temperature, the small circulation temperature may be but is not limited to 80°C, and the engine cooling circuit 100 is a small circulation, that is, the coolant returns to the inlet of the electronic water pump through the small circulation coolant pipeline, and the coolant does not dissipate heat through the radiator 12, so as to quickly increase the coolant temperature; when the coolant temperature rises to not lower than the preset small circulation temperature, the electronic control unit opens the thermal management valve 11, and the engine cooling circuit 100 is a large circulation, that is, the coolant passes through the large circulation pipeline and flows through the radiator 12 to dissipate heat, so as to achieve temperature control of the engine 10.

[0037] When the hydraulic retarder is working, the electronic control unit controls the cooling circuit on-off unit to conduct the engine cooling circuit 100 and the hydraulic retarder cooling circuit 200, so that the heat exchanger 20 participates in the coolant circulation to meet the heat dissipation needs of the hydraulic retarder.

[0038] It can be seen that the present invention mainly enables the engine 10 and the hydraulic retarder to share a cooling circuit, and switches the cooling circuit on and off according to the working state of the hydraulic retarder, so that the vehicle has good heat dissipation performance.

[0039] In the present invention, the electronic water pump 14 realizes the decoupling of the coolant flow in the engine cooling circuit 100 and the speed of the engine 10, and the thermal management valve 11 realizes the decoupling of the thermostat opening and the water temperature in the cooling circuit, realizes the independent control of the electronic water pump 14 from the speed of the engine 10, and realizes the active opening and closing of the thermal management valve 11, which greatly increases the intelligent and refined control of the cooling system, is beneficial to the water temperature of the engine 10, the heat dissipation of the hydraulic retarder, and the precise temperature control of the air-conditioning system in the vehicle, and provides a technical basis for improving the thermal efficiency of the engine 10.

[0040] It should be noted that the hydraulic retarder converts the braking energy of the vehicle into thermal energy, which causes the oil temperature in the hydraulic retarder to rise. The generated heat is transferred to the engine cooling circuit 100 in the form of oil-water heat exchange and dissipated through the cooling module of the cooling circuit. When the hydraulic retarder starts working, while generating braking torque, the vehicle's kinetic energy is converted into thermal energy. The high-temperature and high-pressure oil is cooled and depressurized by the radiator 12 and then flows back to the oil pan. The coolant passes through the radiator 12 to take away the heat. This cycle repeats and the braking torque is continuously generated until the hydraulic retarder is actively turned off or the maximum heat dissipation capacity of the vehicle is reached, and the hydraulic retarder is automatically released.

[0041] like Figure 1 As shown, in this embodiment, the cooling circuit on-off unit includes a first electric three-way valve 30 and a second electric three-way valve 31, the inlet of the first electric three-way valve 30 is connected to the outlet of the electronic water pump 14, one outlet of the first electric three-way valve 30 is connected to the inlet of the engine 10, the other outlet of the first electric three-way valve 30 is connected to the inlet of the heat exchanger 20, the outlet of the heat exchanger 20 is connected to the outlet of the engine 10, and the second electric three-way valve 31 is respectively connected to the inlet of the thermal management valve 11, the outlet of the engine 10 and the outlet of the heat exchanger 20.

[0042] When the engine cooling circuit 100 and the hydraulic retarder cooling circuit 200 are switched on and off, the electronic control unit can simply control the first electric three-way valve 30 and the second electric three-way valve 31 to switch directions.

[0043] In this embodiment, the cooling circuit on-off unit includes a bypass valve and a bypass pipeline, and the bypass valve is connected to the outlet of the heat exchanger 20. When it is necessary to disconnect the engine cooling circuit 100 and the hydraulic retarder cooling circuit 200, the bypass valve can also be controlled to be opened so that the outlet of the heat exchanger 20 is connected to the bypass pipeline to bypass the heat exchanger 20 so that the heat exchanger 20 does not participate in the coolant circulation. When it is necessary to conduct the engine cooling circuit 100 and the hydraulic retarder cooling circuit 200, the bypass valve is controlled to be closed so that the outlet of the heat exchanger 20 is disconnected from the bypass pipeline so that the heat exchanger 20 participates in the coolant circulation.

[0044] In this embodiment, the temperature detection unit includes an ambient temperature sensor, a coolant temperature sensor and a cylinder head temperature sensor; the ambient temperature sensor is used to detect the ambient temperature, and the electronic control unit controls the thermal management valve 11 according to the coolant temperature; the coolant temperature sensor is used to detect the coolant temperature at the outlet of the engine 10, and the electronic control unit controls the thermal management valve 11, the electronic fan 13 and the intake grid switch according to the coolant temperature; the cylinder head temperature sensor is used to detect the cylinder head temperature, and the electronic control unit controls the electronic water pump 14 according to the cylinder head temperature.

[0045] The rotation speed of the electronic fan 13 is related to the coolant temperature. When the coolant temperature is lower than 90°C, the electronic fan 13 runs at a lower basic rotation speed. After the coolant temperature exceeds 90°C, the rotation speed of the electronic fan 13 executes a MAP table related to the coolant temperature. The higher the coolant temperature, the higher the rotation speed of the electronic fan 13. At the same time, the rotation speed of the electronic fan 13 is related to the power of the engine 10. When the power of the engine 10 increases sharply, feedforward intervenes. For example, when the accelerator is stepped on hard, the electronic fan 13 will be turned on in advance to ensure that the engine 10 can be cooled safely.

[0046] When the coolant temperature is lower than 80°C, the thermal management valve 11 opens according to the MAP table set with the coolant temperature. When the coolant temperature rises above 80°C, the opening of the thermal management valve 11 enters PID control to pursue the target temperature. The target temperature of the thermal management valve 11 is related to the power of the engine 10. The higher the power of the engine 10, the lower the target water temperature, which is approximately around 90°C. When the power of the engine 10 is low, the target water temperature is high, and the optimal temperature is around 93°C.

[0047] In this embodiment, after the speed of the electronic fan 13 is increased, the coolant temperature can be adjusted by adjusting the speed. At the same time, the thermal management valve 11 adjusts the coolant temperature by adjusting the opening. During actual operation, the coolant temperature is preferentially adjusted by adjusting the speed of the electronic fan 13. At this time, the thermal management valve 11 does not operate. In this way, the service life of the thermal management valve 11 is increased.

[0048] In addition, in the present invention, the thermal management valve 11 is controlled by a set of PID controls and is related to the coolant temperature △T. The speed of the electronic fan 13 is controlled by feedforward (power mutation) and the water coolant temperature △T. The speed of the electronic water pump 14 is controlled by the cylinder head temperature △T. The action frequency can be controlled by the water temperature difference △T and the water temperature change slope. Within the safe range, the action frequency can be reduced and the action amplitude can be increased. When the water temperature difference △T is large or the water temperature change slope is large, the action frequency is appropriately increased. When the heat generation power of the car is greater than the heat dissipation power when the thermal management valve 11 is fully open and the electronic fan 13 does not intervene, the thermal management valve 11 should be kept fully open in a large cycle and controlled by the electronic fan 13. When the heat generation power of the car is small, it is controlled by the thermal management valve 11 and the electronic fan 13 does not need to intervene.

[0049] The present invention uses an electronic fan 13, an electronic water pump 14, a first electric three-way valve 30, a second electric three-way valve 31, an electronic control unit, a temperature detection unit, an intake grid, etc. to jointly control the coolant temperature and the cylinder head temperature of the engine 10; the optimal cylinder head temperature of the engine 10 is 370°C when the power is high, and the optimal cylinder head temperature is 360°C when the power is low, and the maximum cannot exceed 380°C.

[0050] like Figure 1 As shown, the commercial vehicle thermal management system of the present invention also includes an expansion water tank 15, which is connected to the pipeline between the thermal management valve 11 and the electronic water pump 14 through a first exhaust pipe 16, and the outlet of the expansion water tank 15 is connected to the inlet of the electronic water pump 14 through a return pipe 18, and the pipeline between the thermal management valve 11 and the radiator 12 is connected to the expansion water tank 15 through a second exhaust pipe 17.

[0051] Embodiment 2:

[0052] A control method for a commercial vehicle thermal management system is applied to the commercial vehicle thermal management system described in Example 1. Figure 1 The control method of the present invention comprises the following steps: cooling circuit control, thermal management valve control, electronic water pump control and air inlet grille control.

[0053] Cooling circuit control: when the hydraulic retarder is not working, the cooling circuit on-off unit disconnects or bypasses the hydraulic retarder cooling circuit; when the hydraulic retarder is in working state, the cooling circuit on-off unit connects the engine cooling circuit and the hydraulic retarder circuit;

[0054] Thermal management valve control: when the coolant temperature is lower than the small cycle temperature, the thermal management valve is closed for small cycle cooling; when the coolant temperature is not lower than the small cycle temperature, the thermal management valve is opened for large cycle cooling, and the opening of the thermal management valve is PID controlled according to the coolant temperature and the engine speed; the thermal management valve control also includes: when the opening of the thermal management valve is PID controlled according to the coolant temperature and the engine speed, the optimal thermal management valve opening is obtained from different calibrated MAP tables according to the ambient temperature, coolant temperature and engine power.

[0055] Specifically, when the coolant temperature is below 90°C, the thermal management valve executes according to the MAP table set with the coolant temperature, where the MAP table can be calibrated and the parameters are set to zero by default. If there is a need for use in the future, it can be calibrated again. When the coolant temperature rises above 90°C, the thermal management valve enters PID control to pursue the target temperature. The target temperature of the thermal management valve is related to the engine power, and the three PID parameters are related to the current power. A MAP table with three PID parameters is generated according to the current power. Multiple different MAP tables are required for different current ambient temperatures. Here, the ambient temperature can be set to three MAP tables: extreme cold, normal temperature, and extreme heat. The values ​​of the three PID parameters are obtained according to the current power. According to the changing trend of the water temperature and different working conditions, different responses are given, and the optimal opening of the valve body is output every N seconds (this N value is related to the current water temperature to form a MAP, and the response speed is related to the current water temperature and can be calibrated). The flow rate of the large circulating water is adjusted, and then the cooling water flowing into the engine is adjusted. The target water temperature can be calibrated. The higher the engine power, the lower the target water temperature. In low-power state, the optimal water temperature is around 95°C, and in high-power condition, the optimal temperature is around 93°C. The control effect can control the water temperature within the target value ±2°C range.

[0056] In this embodiment, when the engine power increases sharply, feedforward intervenes. For example, when stepping on the accelerator, turning on the downhill hydraulic retarder, going uphill, etc., the thermal management valve large cycle will open a certain degree in advance, and use this part of the overshoot to take away this part of the heat, ensuring that the engine can cool down normally, and the cylinder head temperature will not overheat and the water temperature will not fluctuate violently.

[0057] The electronic water pump control obtains the corresponding water pump speed according to the cylinder head temperature and engine power, and controls the electronic water pump in an open loop according to the water pump speed.

[0058] Specifically, the control of the electronic water pump is related to the cylinder head temperature and engine power. The speed control of the electronic water pump is a MAP table that uses the cylinder head temperature and engine power to control the engine. The control method is open-loop control. For example, when the cylinder head temperature target value is 360°C when the engine is low power and 370°C when the cylinder head temperature target value is high power, the speed of the electronic water pump is related to the △T between the actual temperature and the target temperature. The larger the △T, the faster the speed of the electronic water pump.

[0059] Electronic fan control, when the coolant temperature is lower than the preset temperature threshold, the electronic fan runs at a lower basic speed. When the coolant temperature is not lower than the preset temperature threshold, the corresponding fan speed is obtained according to the coolant temperature and engine power, and the electronic fan is controlled according to the fan speed. A preferred solution is that after the electronic fan increases its speed, the electronic fan is used to adjust the temperature first, and the thermal management valve does not operate. When the engine heating power is greater than the heat dissipation power when the thermal management valve is fully open and the electronic fan does not intervene, the thermal management valve is kept fully open in a large cycle and controlled by the electronic fan. When the engine heating power is smaller, it is controlled by the thermal management valve again, and the electronic fan does not need to intervene.

[0060] Specifically: the speed of the electronic fan is related to the coolant temperature. When the coolant temperature is lower than 94°C, the electronic fan runs at a lower basic speed. After the coolant temperature exceeds 94°C, the speed of the electronic fan executes a MAP table related to the coolant temperature. The higher the coolant temperature, the higher the speed of the electronic fan. The thermal management valve and the electronic fan are used in combination. Open the thermal management valve first. If the coolant temperature still has an upward trend, then speed up the electronic fan. This is achieved by setting the temperature value. The target temperature of the electronic fan is always p°C higher than the thermal management valve (this p is a calibrable quantity). In the present invention, when the engine power suddenly increases, the electronic fan is turned on in advance.

[0061] Air inlet grille control: when the coolant temperature is lower than the preset temperature threshold, the air inlet grille is closed; when the coolant temperature is not lower than the preset temperature threshold, the air inlet grille is opened.

[0062] Specifically, when the engine coolant temperature is lower than 90°C, the electronic control unit controls the air intake grille to be in a closed state, reducing the engine headwind and increasing the engine operating coolant temperature. When the engine operating coolant temperature is higher than 90°C, the air intake grille is opened to increase the engine cooling headwind and increase the engine heat dissipation capacity. In the present invention, when the engine power increases suddenly and the time exceeds 1S, the air intake grille is opened in advance to cool the engine in advance.

[0063] In this embodiment, when the coolant temperature exceeds 99° C., a temperature alarm is triggered, the thermal management valve is fully opened, the electronic fan runs at full speed, and the electronic water pump runs at maximum power.

[0064] After the present invention is put into use, when the hydraulic retarder is not working, the heat exchanger is not involved in the cooling cycle of the coolant by controlling the action of the cooling circuit on-off unit. At this time, the large cycle and small cycle in the engine cooling circuit are completely consistent with the vehicle model without hydraulic retarder. When the coolant temperature is low, the coolant returns to the coolant pump inlet through the small cycle coolant pipeline, and the coolant does not dissipate heat through the radiator, so as to quickly increase the coolant temperature; when the coolant temperature rises and the thermal management valve is opened, the coolant passes through the large cycle pipeline and flows through the radiator 1 to dissipate heat, so as to achieve temperature control of the engine. When the hydraulic retarder is working, the heat exchanger is involved in the coolant circulation by controlling the action of the cooling circuit on-off unit to meet the heat dissipation needs of the hydraulic retarder.

[0065] In addition, the present invention has an engine torque change compensation method, specifically: filtering out torque mutations caused by gear shifting (automatic gear shifting time is 1-2 seconds); performing angle compensation according to the slope of the change (the specific compensation is calibrated by the slope CURVE), and the compensation time can be calibrated; the slope is achieved by creating a torque queue of 5 elements, and an engine torque value is queued every second.

[0066] In addition, since the hydraulic retarder and the engine share a cooling system, in order to avoid the coolant boiling and the hydraulic retarder brake oil temperature being too high, a suitable control strategy must be formulated for the hydraulic retarder, and the following principles should be followed: (1) When the coolant temperature is ≥105°C, the hydraulic retarder automatically stops working; (2) When the coolant temperature is ≥95°C, the hydraulic retarder gradually limits the torque; (3) When the hydraulic retarder is working, the electronic fan should run at full speed; (4) When braking and accelerating, the hydraulic retarder should automatically stop working. (5) The hydraulic retarder should have constant speed and different brake gears.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made within the spirit and principles of the present invention, improvements to a commercial vehicle thermal management system and its control method, etc., should be included in the protection scope of the present invention.

Claims

1. A commercial vehicle thermal management system, comprising an electronic control unit, an engine cooling circuit and a hydraulic retarder cooling circuit; The engine cooling circuit includes an engine, a thermal management valve, a radiator, an electronic water pump and an electronic fan arranged behind the radiator, and the thermal management valve, the electronic water pump and the electronic fan are electrically connected to the electronic control unit respectively; The hydraulic retarder cooling circuit includes a heat exchanger; An air intake grille is arranged in front of the radiator; It is characterized in that The system further comprises a cooling circuit on-off unit and a temperature detection unit, wherein the cooling circuit on-off unit and the temperature detection unit are electrically connected to the electric control respectively; The cooling circuit on-off unit is used to switch on and off the hydraulic retarder cooling circuit and the engine cooling circuit, and / or the cooling circuit on-off unit is used to bypass the hydraulic retarder cooling circuit; The temperature detection unit is used to detect the ambient temperature, the coolant temperature and / or the cylinder head temperature, and transmit the corresponding temperature signal to the electronic control unit, and the electronic control unit controls the thermal management valve, the electronic water pump, the electronic fan and the intake grille switch according to the temperature signal; The electronic control unit controls the cooling circuit on-off unit according to the working state of the hydraulic retarder to switch on and off the hydraulic retarder cooling circuit and the engine cooling circuit.

2. The commercial vehicle thermal management system according to claim 1, characterized in that: The cooling circuit on-off unit includes a first electric three-way valve, an inlet of the first electric three-way valve is connected to the outlet of the electronic water pump, one outlet of the first electric three-way valve is connected to the inlet of the engine, the other outlet of the first electric three-way valve is connected to the inlet of the heat exchanger, and the outlet of the heat exchanger is connected to the engine outlet.

3. The commercial vehicle thermal management system according to claim 2, characterized in that: The cooling circuit on-off unit includes a second electric three-way valve, which is respectively connected to an inlet of the thermal management valve, an outlet of the engine, and an outlet of the heat exchanger.

4. The commercial vehicle thermal management system according to claim 1, characterized in that: The cooling circuit on-off unit comprises a bypass valve and a bypass pipeline, and the bypass valve is connected to the outlet of the heat exchanger.

5. The commercial vehicle thermal management system according to claim 1, characterized in that: The temperature detection unit includes an ambient temperature sensor, a coolant temperature sensor and a cylinder head temperature sensor; The ambient temperature sensor is used to detect the ambient temperature, and the electronic control unit controls the thermal management valve according to the coolant temperature; The coolant temperature sensor is used to detect the coolant temperature at the engine outlet, and the electronic control unit controls the thermal management valve, the electronic fan and the intake grille switch according to the coolant temperature; The cylinder head temperature sensor is used to detect the cylinder head temperature, and the electronic control unit controls the electronic water pump according to the cylinder head temperature.

6. A control method for a commercial vehicle thermal management system, characterized in that: Applied to the commercial vehicle thermal management system according to any one of claims 1 to 5, the control method comprises the following steps: Cooling circuit control: when the hydraulic retarder is not working, the cooling circuit on-off unit disconnects or bypasses the hydraulic retarder cooling circuit; when the hydraulic retarder is in working state, the cooling circuit on-off unit connects the engine cooling circuit and the hydraulic retarder circuit; Thermal management valve control: when the coolant temperature is lower than the small cycle temperature, the thermal management valve is closed for small cycle cooling; when the coolant temperature is not lower than the small cycle temperature, the thermal management valve is opened for large cycle cooling, and the opening of the thermal management valve is PID controlled according to the coolant temperature and engine speed; Electronic water pump control, according to the cylinder head temperature and engine power, obtains the corresponding water pump speed, and controls the electronic water pump in an open loop according to the water pump speed; Electronic fan control: when the coolant temperature is lower than the preset temperature threshold, the electronic fan runs at a lower basic speed; when the coolant temperature is not lower than the preset temperature threshold, the corresponding fan speed is obtained according to the coolant temperature and engine power, and the electronic fan is controlled according to the fan speed; Air inlet grille control: when the coolant temperature is lower than the preset temperature threshold, the air inlet grille is closed; when the coolant temperature is not lower than the preset temperature threshold, the air inlet grille is opened.

7. The control method of the commercial vehicle thermal management system according to claim 6, characterized in that: The control method further includes: When the engine power suddenly increases and lasts longer than a preset time, the air intake grille opens in advance to cool the engine in advance; When the engine power suddenly increases, the electronic fan is turned on in advance; and / or; When the engine power suddenly increases, the thermal management valve opens a certain degree in advance.

8. The control method of the commercial vehicle thermal management system according to claim 6, characterized in that: The control method further includes: When the electronic fan increases its speed, the electronic fan is used to adjust the coolant temperature at the engine outlet, and the thermal management valve does not operate; When the engine heat generation power is greater than the heat dissipation power when the thermal management valve is fully opened and the electronic fan does not intervene, the thermal management valve is kept fully open in large circulation, and the electronic fan adjusts the coolant temperature at the engine outlet; When the engine heat output is low, the thermal management valve will adjust the coolant temperature at the engine outlet, and the electronic fan does not need to intervene.

9. The control method of the commercial vehicle thermal management system according to claim 6, characterized in that: The thermal management valve control further includes: When the opening of the thermal management valve is PID controlled according to the coolant temperature and the engine speed, the optimal thermal management valve opening is obtained from different calibrated MAP tables according to the ambient temperature, the coolant temperature and the engine power.

10. The control method of the commercial vehicle thermal management system according to claim 6, characterized in that: The control method further includes: When the coolant temperature exceeds 99°C, the temperature alarm is triggered, the thermal management valve is fully opened, the electronic fan runs at full speed, and the electronic water pump runs at maximum power.

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