The water pump is the heart of the liquid delivery of the automobile cooling system, and its normal operation has an important impact on the operation, reliability and comfort of the vehicle. According to different power sources, automotive water pumps can be divided into mechanical water pumps and electronic water pumps. Among them, the biggest advantage of the electronic coolant pump is that the speed can be controlled, which can not only reduce energy consumption, but also improve the heat dissipation effect. Hoon Cho et al. used electronically controlled electric water pumps to replace traditional water pumps. Through experiments and simulation analysis, they found that by controlling the speed of water pumps and improving the efficiency of electronically controlled water pumps, the power consumption was reduced by more than 87%. If the speed of water pumps is increased to the maximum value, The radiator size can be reduced by more than 27%, which has great potential for improving engine performance and fuel economy.

Different from the optimized design of traditional mechanical water pumps, the speed of electronic water pumps is controllable and adjustable, which makes the design of electronic water pumps more flexible and flexible, but at the same time increases the difficulty of designing both efficiency and energy consumption. This paper will refer to the existing pump design, adjust and optimize according to the new project requirements, and predict through numerical simulation before the test verification, so as to avoid invalid tests and speed up the development and design process of the pump.

1 Vehicle electronic water pump demand matching

The working temperature of the driving system of new energy vehicles and the thermal management system of the power battery is quite different, so the same model often needs to be equipped with multiple water pumps of different specifications to match the cooling cycle of different temperature requirements.

1.1 Analysis of Vehicle Thermal Management Requirements

The drive system includes drive motor, motor controller and reducer. The drive motor and the controller will generate a lot of heat when they are running under heavy load. Excessive temperature is not conducive to the operation of the motor or even burns out. If the temperature of the lubricating oil in the high-speed reducer is too high, the viscosity will decrease, which will affect the lubrication effect. Lithium-ion power batteries of electric vehicles will generate heat during charging and discharging, especially during fast charging and high-power discharging. If the temperature is too high or too low, it will affect the battery life and performance, and even spontaneous combustion. In addition, components such as chargers, inverters and DC transformers also require cooling systems. In this paper, the drive system and power battery are selected as the main cooling objects, and the electronic water pump for vehicles is studied and analyzed.

1.2 Cooling system structure

Based on the research status of electric vehicle cooling system, this paper intends to use water cooling to cool or adjust the temperature of the drive system and power battery. As shown in Figure 1, the vehicle cooling system consists of one “big cycle” and two “small cycles”. In addition to the conventional water-cooling cycle used for the car’s own components, the air-conditioning system for passengers in the car will also be involved in the thermal management of the vehicle to enhance or share the heat in the cooling cycle.

2 Electronic water pump scheme design

The hydraulic mechanical design of the electronic water pump for vehicles is similar to that of the mechanical water pump. The main difference lies in the motor of the electronic water pump and its controller. The speed of the water pump is no longer coupled with the speed of the engine. Matching control commands. Since the development and design process of the electronic water pump used in the power battery cooling system and the driving system cooling system is similar, one of them can be selected as the research object. Here, the electronic coolant pump used in the cooling system of the drive system is taken as an example for research and analysis. The electronic water pump for vehicles consists of three parts: a centrifugal water pump, a brushless DC motor (Brushless Direct Motor, BLDC Motor) and a motor controller. Among them, the impeller of the water pump is integrated with the shaft of the motor, so the structure is compact and the mechanical loss is small. The rotor of the motor drives the impeller of the water pump to rotate, sucking in the coolant from the vertical direction and throwing it to the inner wall of the pump volute. and energy into the next cycle.