Introduction to automotive thermal management knowledge
The automobile is a complex industrial product, consisting of many parts and assemblies, and each part's working temperature and material tolerance temperature are different. Only by ensuring that they operate at an appropriate temperature can the safe, efficient, and stable operation of the automobile be guaranteed. The automotive thermal management system is based on the system and the whole vehicle, and coordinates the heat of the whole vehicle and the ambient heat to keep each component working in the optimal temperature range.
Traditional automotive thermal management mainly includes the cooling of the engine and gearbox and the thermal management of the air-conditioning system.
New energy vehicle thermal management includes motor and electronic control system thermal management, battery system thermal management and passenger compartment air-conditioning thermal management.
Thermal management system
1. The difference between fuel vehicles and electric vehicles
Under the trend of electrification, the thermal management system of the whole vehicle has undergone major changes. New energy vehicles without heat engines require additional heat generation devices to maintain the efficient operation of the entire system. The high-temperature sensitivity of batteries makes the complexity and refinement of thermal management of new energy vehicles continue to increase. There is still a big difference between the thermal management of new energy vehicles and the thermal management system of fuel vehicles.
1. Traditional vehicles use engine lung heat to heat the passenger compartment, and new energy vehicles need heating devices to generate heat.
Traditional internal combustion engine vehicles use the waste heat generated by the engine, adjust it to a suitable temperature through the heater core, and blow it into the cockpit through the blower to achieve the purpose of heating the passenger compartment.
Since new energy vehicles do not have the heat generated by the internal combustion engine, they can only obtain additional heat from outside the system through additional PTC resistor heating or heat pump air conditioning to heat the passenger compartment.
2. The thermal management of traditional automobile power systems is mainly cooling, and the power battery needs to be cooled and heated.
After the engine and gearbox of traditional internal combustion engine vehicles run at high speed, a large amount of waste heat is generated, which needs to be discharged in time to ensure the efficient and stable operation of the mechanism. Therefore, the traditional automobile power system is mainly heat dissipation.
The performance of new energy vehicle power batteries is sensitive to temperature. The battery performance is best at 15℃~35℃. Therefore, the power battery thermal management system needs to always control the battery temperature in the appropriate temperature range to maximize the battery performance.
Compared with fuel vehicles, the thermal management system of new energy vehicles has more components and is more complex. The main changes are summarized as follows:
Change 1: Diversification of components, increase in electrical parts, and multiple new parts such as electric compressors, PTC heaters, electromagnetic expansion valves, battery water cooling plates, PTC air heater electromagnetic reversing valves, etc.
Change 2: Complex system, increased thermal management layout. PTC heating and heat pump systems are derived during heating. The three-electric thermal management system is a pure new system that needs to cover the entire chassis.
Change 3: Refined temperature control, higher requirements for software and hardware. The three-electric system is more sensitive to temperature than the engine. At the hardware level: a large number of P/T sensors need to be deployed; at the software level: the pursuit of segmented scenarios and intelligent modes needs to be increased.
