A low-temperature cold start method for a diesel hybrid vehicle

Abstract

The present application relates to a kind of diesel engine hybrid vehicle low temperature cold start method, belong to diesel engine hybrid vehicle start control field.The present application divides into three kinds of situations such as high-voltage electricity, low-voltage electricity is no power failure alarm, high-voltage electricity no power failure alarm, low-voltage battery has power failure alarm, high-voltage electricity has power failure alarm, low-voltage battery no power failure alarm respectively executes cold start.The present application provides a kind of diesel engine hybrid vehicle low temperature cold start method, comprehensively considers the characteristics (ISG motor drag start) of APU start, and the reasonable distribution and use of high-voltage electricity and low-voltage electricity.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of diesel engine hybrid vehicle starting control, and particularly relates to a low-temperature cold starting method for a diesel engine hybrid vehicle. BACKGROUND

[0002] The currently commonly used low-temperature cold starting method for a diesel engine hybrid vehicle is as follows: firstly, the power battery control system makes a preliminary judgment on whether the power battery needs to be preheated to meet the discharge requirement, at this time, the diesel engine hybrid device (APU) also needs to make a judgment on whether the power unit needs to be preheated. When the preheating of the power battery and the APU is completed, the power battery provides energy to enable the integrated motor (ISG motor) to drag the diesel engine to start, at this time, the intake of the APU diesel engine is heated to ensure that the combustion of the APU diesel engine can be self-sustaining (not extinguished) at low temperature.

[0003] The preheating method of the power battery is generally to heat the cooling water inside the battery pack to warm up the battery pack, and the water heating method is to heat by PTC (high pressure) or to heat by burning fuel by the fuel parking heater (low pressure). The preheating method of the APU is generally to preheat the intake of the diesel engine, including heating the intake by the intake grille (low pressure) and heating the intake by the preheating plug (low pressure). The feature of this separate control preheating method is that the power battery has its own low-temperature starting method, and the APU also has its own low-temperature starting method, which are decoupled from each other; the advantage is that the low-temperature cold starting control method of the hybrid vehicle is relatively simple.

[0004] The problem of this cold starting preheating method is that the energy loss of the high-voltage electricity of the power battery or the low-voltage power distribution of the vehicle is very large in a low-temperature environment, and it is easy to cause starting failure due to lack of high-voltage electricity or low-voltage power. In order to more effectively realize low-temperature cold starting, it is necessary to comprehensively control the discharge capacity of the power battery of the vehicle and the low-temperature cold starting method of the APU. SUMMARY

[0005] (I) Technical problem to be solved

[0006] The technical problem to be solved by the present application is how to provide a low-temperature cold starting method for a diesel engine hybrid vehicle to solve the problem that the energy loss of the high-voltage electricity of the power battery or the low-voltage power distribution of the vehicle is very large in a low-temperature environment, and it is easy to cause starting failure due to lack of high-voltage electricity or low-voltage power in the prior art.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present application provides a low-temperature cold starting method for a diesel engine hybrid vehicle, which comprises the following steps:

[0009] Power battery low temperature cold start requirement: power battery temperature < Td1, power battery enters preheating mode, when power battery temperature > Td2, stop heating;

[0010] APU diesel engine low temperature cold start requirement:

[0011] Diesel engine cooling water temperature < Tc1, and environment temperature < T0, enter intake air heating mode;

[0012] Diesel engine cooling water < Tc2, while diesel engine intake air heating, need to perform cooling water heating mode;

[0013] Vehicle cooling water heating mode: PTC heating;

[0014] Vehicle starting mode: heuristic integrated ISG motor starting mode;

[0015] For high voltage and low voltage, there is no power failure alarm, high voltage power failure alarm, low voltage battery power failure alarm, high voltage power failure alarm, low voltage battery power failure alarm respectively cold start control.

[0016] (Three) beneficial effects

[0017] The application provides a diesel engine hybrid vehicle low temperature cold start method, and comprehensively considers the characteristics of APU starting (ISG motor drag starting) and reasonable distribution and utilization of high voltage and low voltage. Specific implementation

[0018] In order to make the purpose, content and advantages of the application more clear, the specific implementation of the application will be further described in combination with examples.

[0019] The application relates to the field of diesel engine hybrid vehicle starting control, and particularly relates to a hybrid vehicle cold start control method in a severe cold environment.

[0020] The application provides a diesel engine hybrid vehicle low temperature cold start method, and comprehensively considers the characteristics of APU starting (ISG motor drag starting) and reasonable distribution and utilization of high voltage and low voltage.

[0021] Under low temperature conditions, the circulating water preheating of the power battery not only needs to heat the power battery, but also needs to realize the heating of the circulating water in the engine according to the control requirements.

[0022] The whole vehicle needs to be determined:

[0023] 1) Under low temperature conditions, the highest temperature of the power battery needs to be heated.

[0024] 2) The highest engine internal cooling water temperature and ambient temperature at which the diesel engine requires intake air preheating under low temperature conditions of the hybrid power unit (APU); and the diesel engine cooling water temperature and ambient temperature at which the diesel engine cannot work for a long time under low temperature environment and ISG dragging.

[0025] The whole vehicle control system needs to collect: power battery temperature, diesel engine internal cooling water temperature, ambient temperature, and discharge capacity of the power battery and low voltage battery to comprehensively evaluate and determine the appropriate low temperature cold start mode.

[0026] Vehicle cooling water heating mode: PTC heating (high voltage electricity);

[0027] Vehicle starting mode: ISG motor starting mode.

[0028] Under the above premise: when the low voltage battery appears alarm, the power consumption of the intake air heater supplied by the low voltage battery is reduced by heating the engine internal cooling water or changing the ISG motor starting strategy.

[0029] When the power battery (high voltage electricity) appears alarm, the power consumption of the PTC heater is reduced by changing the ISG motor starting strategy.

[0030] The present application provides a low temperature cold start method for a diesel engine hybrid vehicle, specifically comprising:

[0031] Power battery low temperature cold start requirement: power battery temperature < Td1, power battery enters preheating mode, when power battery temperature > Td2, stop heating;

[0032] APU diesel engine low temperature cold start requirement:

[0033] Diesel engine cooling water temperature < Tc1, and ambient temperature < T0, enter intake air heating mode;

[0034] Diesel engine cooling water < Tc2, while diesel engine intake air heating, cooling water heating mode is required;

[0035] Vehicle cooling water heating mode: PTC heating (high voltage electricity);

[0036] Vehicle starting mode: ISG motor starting mode.

[0037] According to the above requirements, the cold start control mode of the diesel engine hybrid vehicle is as follows:

[0038]

[0039]

[0040] Note: Tc2 < T0 < Tc1; Te3 < Te1 < Te2

[0041] The specific control method of the present application is as follows:

[0042] 1. Low-temperature cold start requirements of the power battery: the cooling water temperature of the power battery is <5℃, and the ambient temperature is <-10℃, the power battery enters the preheating mode;

[0043] 2. Low-temperature cold start requirements of the APU diesel engine:

[0044] 1) The cooling water temperature of the diesel engine is <-5℃, and the ambient temperature is <-10℃, the intake air heating mode is entered;

[0045] 2) The cooling water of the diesel engine is <-30℃, and the cylinder heating is needed while the intake air heating of the diesel engine is performed;

[0046] 3. Vehicle cooling water heating mode: PTC heating (high-voltage electricity); vehicle starting mode: ISG motor starting mode.

[0047] 4. According to the above requirements, the cold start control mode of the diesel engine hybrid vehicle is as follows:

[0048] T0=-10℃; Tc1=-5℃; Tc2=-30℃

[0049] Te3=-10℃; Te1=10℃; Te2=40℃

[0050] Td1=5℃; Td2=10℃

[0051] 4.1 When there is no power shortage alarm for high-voltage electricity and low-voltage battery

[0052] 4.1.1 When the ambient temperature is >-10℃:

[0053] When the battery temperature is <5℃, the PTC heater heats the circulating water of the power battery until the battery temperature is >10℃, and the heating is stopped.

[0054] -10℃

[0055] Table 1 Intake air preheating time

[0056]

[0057] Table 2 Intake air post-heating time

[0058]

[0059]

[0060] 4.1.2 -30℃ < ambient temperature < -10℃:

[0061] When the temperature of the battery circulating water is < 5℃, the PTC heater heats the battery circulating water until the battery temperature is > 10℃.

[0062] When the temperature of the diesel engine circulating water is -30℃ < T < -5℃, the APU intake air is preheated. The preheating time is shown in Table 1. After preheating, the intake air is heated according to Table 2.

[0063] 4.1.3 ambient temperature < -30℃:

[0064] When the temperature of the battery circulating water is < 5℃, the PTC heater heats the battery circulating water until the battery temperature is > 10℃.

[0065] When the temperature of the diesel engine circulating water is < -30℃, the PTC heater opens the four-way valve and heats the diesel engine circulating water until the temperature of the circulating water is > 40℃. At the same time, the APU intake air is preheated. The preheating time is shown in Table 1. After preheating, the intake air is heated according to Table 2.

[0066] 4.2 When the high-voltage battery is not powered and the low-voltage battery is powered.

[0067] 4.2.1 ambient temperature > -10℃:

[0068] When the temperature of the battery circulating water is < 5℃, the PTC heater heats the battery circulating water until the battery temperature is > 10℃.

[0069] When the temperature of the diesel engine circulating water is -10℃ < T < -5℃, the APU runs at a constant low speed by ISG speed control mode. The running time is shown in Table 3. The diesel engine is heated by piston movement to achieve diesel engine start. The APU does not need intake air preheating, which reduces the power consumption of the low-voltage battery. isg isg

[0070] Table 3 Motor drag time

[0071] Engine water temperature °C -43 -35 -25 -20 -15 -10 -5 0 Ambient temperature °C -45 -35 -30 -25 -20 -15 -10 -5 Time s 120 180 180 120 120 120 120 120 ​​

[0072] 4.2.2 When -30°C < ambient temperature < -10°C:

[0073] When the battery circulating water temperature < 5°C, the PTC heater heats the battery circulating water until the battery temperature > 10°C, and stops heating.

[0074] When -30°C < diesel engine internal circulating cooling water temperature < -10°C, the PTC heater opens the four-way valve to heat the diesel engine internal circulating cooling water until the cooling water temperature > 10°C, and stops heating. In this way, the diesel engine cooling water temperature is increased, thereby increasing the diesel engine body temperature, and the APU starting performance is improved. At this time, the intake air starts to be preheated, and the intake air preheating time is checked in Table 1 and the intake air post-heating time table is checked in Table 2.

[0075] 4.2.3 When ambient temperature < -30°C:

[0076] When the battery circulating water temperature < 5°C, the PTC heater heats the battery circulating water until the battery temperature > 10°C, and stops heating.

[0077] When the diesel engine internal circulating cooling water temperature < -30°C, the PTC heater opens the four-way valve to heat the diesel engine internal circulating cooling water until the cooling water temperature > 40°C, and stops heating. In this way, the diesel engine body temperature is increased, thereby improving the APU starting conditions. Then the intake air is preheated, and the intake air preheating time is checked in Table 1 and the intake air post-heating time table is checked in Table 2.

[0078] 4.3 When there is a high-voltage power shortage alarm and there is no low-voltage battery power shortage alarm.

[0079] 4.3.1 When ambient temperature > -10°C:

[0080] When the battery temperature < 5°C, the PTC heater heats the battery circulating water until the battery temperature > 10°C, and stops heating

[0081] When -10°C < diesel engine internal circulating cooling water temperature < -5°C, the APU intake air is preheated. The preheating time is checked in Table 1. After preheating, the normal low-temperature cold starting condition is entered, and the intake air post-heating time is checked in Table 2.

[0082] 4.3.2 When -30°C < ambient temperature < -10°C:

[0083] When the battery temperature < 5°C, the PTC heater heats the battery circulating water until the battery temperature > 10°C, and stops heating

[0084] When -30°C < diesel engine internal circulating cooling water temperature < -10°C, the APU intake air is preheated. The preheating time is checked in Table 1. After preheating, the normal low-temperature cold starting condition is entered, and the intake air post-heating time is checked in Table 2.

[0085] 4.3.3, when ambient temperature ≤-30℃:

[0086] When the power battery circulating water temperature <5℃, the PTC heater heats the power battery circulating water until the battery temperature >10℃ to stop heating.

[0087] When the diesel engine internal circulating cooling water temperature ≤-30℃, the PTC heater opens the four-way valve to heat the diesel engine internal circulating cooling water until the cooling water temperature >-10℃ to stop heating. At the same time, the APU runs at a constant low speed by ISG speed control mode, and the ISG motor drives the APU to run. The running time is checked in Table 3 motor drag time table. After the drag ends, the APU intake preheating, the preheating time is checked in Table 1 intake preheating time and Table 2 intake post-heating time table. The diesel engine is started.

[0088] The present application provides a kind of diesel engine hybrid vehicle low temperature cold start method, it has considered the characteristics (ISG motor drag start) of APU start, and the reasonable distribution and use of high voltage and low voltage.

[0089] The above only is the preferred embodiment of the present application, it should be pointed out, for the ordinary skill in the art, without departing from the technical principles of the present application, can also make a number of improvements and deformation, these improvements and deformation also should be considered as the protection scope of the present application.

Claims

1. A method for low-temperature cold starting of a diesel engine hybrid vehicle, characterized in that, The method includes: Low-temperature cold start requirements for power batteries: When the power battery temperature is <Td1, the power battery enters the preheating mode; when the power battery temperature is >Td2, heating stops. APU diesel engine low-temperature cold start requirements: When the diesel engine coolant temperature is <Tc1 and the ambient temperature is <T0, the engine enters intake air heating mode. If the diesel engine coolant temperature is <Tc2, the coolant heating mode must be activated while the diesel engine intake air is being heated. Vehicle coolant heating method: PTC heating; Vehicle starting method: Integrated ISG motor starting method; Cold start control is performed for situations where neither high-voltage nor low-voltage electricity has a power shortage alarm, high-voltage electricity has no power shortage alarm but low-voltage battery has a power shortage alarm, and high-voltage electricity has a power shortage alarm but low-voltage battery has no power shortage alarm.

2. The low-temperature cold start method for diesel engine hybrid vehicles as described in claim 1, characterized in that, Td1=5℃; Td2=10℃.

3. The low-temperature cold start method for diesel engine hybrid vehicles as described in claim 1, characterized in that, T0=-10℃; Tc1=-5℃; Tc2=-30℃.

4. The low-temperature cold start method for diesel engine hybrid vehicles as described in claim 1, characterized in that, This method needs to determine: The highest temperature at which a power battery needs to be heated under low-temperature conditions; The maximum internal engine coolant temperature and ambient temperature required for intake air preheating in a hybrid power unit (APU) under low-temperature conditions; and the engine coolant temperature and ambient temperature at which the diesel engine cannot operate for extended periods under ISG drag in low-temperature environments. The vehicle control system needs to collect data on the following: power battery temperature, diesel engine internal coolant temperature, ambient temperature, and comprehensively evaluate the discharge capacity of the power battery and the discharge capacity of the low-voltage battery to determine a suitable low-temperature cold start method.

5. The low-temperature cold start method for diesel engine hybrid vehicles as described in claim 1, characterized in that, The method includes: when the low-voltage battery alarms, reducing the power consumption of the intake air heater supplied by the low-voltage battery by heating the engine coolant or changing the ISG motor starting strategy; when the power battery alarms, reducing the power consumption of the PTC heater by changing the ISG motor starting strategy.

6. The low-temperature cold start method for diesel engine hybrid vehicles as described in any one of claims 1-5, characterized in that, When neither the high-voltage power supply nor the low-voltage battery alarm is triggered: When the ambient temperature is >-10℃: When the battery temperature is <5℃, the PTC heater heats the circulating water of the power battery until the battery temperature is >10℃ and then stops heating. -10℃ < diesel engine internal circulating cooling water temperature < -5℃, APU intake air is preheated; preheating time can be found in the heating device heating time pulse map t=f(T,T0), where t is the heater energization time in seconds, T is the cooling water temperature in degrees Celsius, and T0 is the ambient temperature in degrees Celsius; after preheating, it enters the normal low temperature cold start condition. When -30℃ < ambient temperature ≤ -10℃: When the temperature of the power battery circulating water is <5℃, the PTC heater heats the power battery circulating water until the battery temperature is >10℃ and then stops heating. When the diesel engine internal cooling water temperature is between -30℃ and -5℃, the APU intake air is preheated. The preheating time is shown in the heating time pulse map of the heating device. After preheating, the engine enters the normal low-temperature cold start condition. When the ambient temperature is ≤-30℃: When the temperature of the power battery circulating water is <5℃, the PTC heater heats the power battery circulating water until the battery temperature is >10℃ and then stops heating. When the internal cooling water temperature of the diesel engine is ≤-30℃, the PTC heater opens the four-way valve to heat the internal cooling water of the diesel engine until the cooling water temperature is >40℃ and then stops heating; at the same time, the APU intake air is preheated; the preheating time is checked by the heating time pulse map of the heating device. After preheating, it enters the normal low temperature cold start condition.

7. The low-temperature cold start method for diesel engine hybrid vehicles as described in any one of claims 1-5, characterized in that, When there is no low-voltage alarm for the high-voltage power supply but a low-voltage alarm for the low-voltage battery: When the ambient temperature is >-10℃: When the circulating water temperature of the power battery is <5℃, the PTC heater heats the circulating water of the power battery until the battery temperature is >10℃ and then stops heating. -10℃ < diesel engine internal cooling water temperature < -5℃. The APU uses ISG speed control mode to drive the APU to run at a constant low speed. The running time can be viewed by checking the low temperature cold start reverse pulse. The piston movement heats the diesel engine cylinder to start the diesel engine. The APU does not require intake air preheating, which reduces the power consumption of the low-voltage battery. When -30℃ < ambient temperature ≤ -10℃: When the circulating water temperature of the power battery is <5℃, the PTC heater heats the circulating water of the power battery until the battery temperature is >10℃ and then stops heating. When the temperature of the diesel engine's internal circulating coolant is between -30℃ and -10℃, the PTC heater opens the four-way valve to heat the diesel engine's internal circulating coolant until the coolant temperature exceeds 10℃. This method increases the diesel engine's coolant temperature, thereby raising the engine block temperature and improving the APU's starting performance. At this time, the intake air begins to preheat. The heating time of the heating device can be found in the intake air preheating time and intake air postheating time table. When the ambient temperature is ≤-30℃: When the temperature of the power battery circulating water is <5℃, the PTC heater heats the power battery circulating water until the battery temperature is >10℃ and then stops heating. The internal cooling water temperature of the diesel engine is ≤-30℃. The PTC heater opens the four-way valve to heat the internal cooling water of the diesel engine until the cooling water temperature reaches 40℃, then the heating is stopped. This method increases the engine body temperature of the diesel engine and improves the starting conditions of the APU. Then the intake air is preheated. The intake air preheating time is shown in the intake air preheating time and intake air postheating time table.

8. The low-temperature cold start method for diesel engine hybrid vehicles as described in claim 7, characterized in that, The reverse drag pulse is t isg =f(T, T0), where: t isg T is the motor reversing time, in seconds; T is the cooling water temperature, in degrees Celsius; and T0 is the ambient temperature, in degrees Celsius.

9. The low-temperature cold start method for diesel engine hybrid vehicles as described in any one of claims 1-5, characterized in that, When there is a low-voltage alarm for the high-voltage power supply but no low-voltage alarm for the low-voltage battery: When the ambient temperature is >-10℃: When the battery temperature is <5℃, the PTC heater heats the circulating water of the power battery until the battery temperature is >10℃ and then stops heating. When the temperature of the diesel engine's internal circulating coolant is -10℃ to -5℃, the APU intake air is preheated. The preheating time is shown in the intake air preheating time table. After preheating, the engine enters the normal low-temperature cold start condition. The intake air warm-up time is shown in the intake air warm-up time table. When -30℃ < ambient temperature ≤ -10℃: When the battery temperature is <5℃, the PTC heater heats the circulating water of the power battery until the battery temperature is >10℃ and then stops heating. When the diesel engine internal cooling water temperature is -30℃ to -10℃, the APU intake air is preheated. Check the intake air preheating time table for the preheating time. After preheating, the engine enters the normal low-temperature cold start condition. Check the intake air warm-up time table for the warm-up time. When the ambient temperature is ≤-30℃: When the temperature of the power battery circulating water is <5℃, the PTC heater heats the power battery circulating water until the battery temperature is >10℃ and then stops heating. When the internal circulating coolant temperature of the diesel engine is ≤-30℃, the PTC heater opens the four-way valve to heat the internal circulating coolant until the coolant temperature is >-10℃ and then stops heating. At the same time, the APU uses the ISG speed control mode to drive the ISG motor to run the APU at a constant low speed. The running time can be found in the motor reverse drag time table. After the reverse drag is completed, the APU intake air preheats. The preheating time can be found in the intake air preheating time and intake air post-heating time table to start the diesel engine.

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