Finite element analysis of PTC heating water tank for electric vehicle

- Aug 17, 2020-

In recent years, the trend of global warming has become more and more serious, and people have begun to seek effective methods to alleviate global warming. Because electric vehicles have significant advantages in energy saving, emission reduction and substitution, research on related technologies and applications of electric vehicles has become one of the focuses of many countries in the automotive industry. Electric vehicles use batteries as their driving power, which is very different from traditional fuel vehicles in terms of heating systems. Traditional fuel cars can use the car’s own engine waste heat for heating in winter, but electric cars do not use engine waste heat. Therefore, PTC water heater systems are used in some electric vehicles to heat the passenger compartment [. The working principle of the PTC water heater system: After the PTC water heater system is started, the low-temperature refrigerant is first transported by the electric water pump into the PTC heating water tank, heated in the PTC water tank, and then enters the warm air radiator. The cold air flows through the warm air radiator and absorbs the heat brought by the refrigerant into warm air. The warm air is sent into the car to provide heat to the passenger compartment. However, during the driving of the car, due to the acceleration, deceleration, bumps and lateral movement of the car, the force of the PTC heating water tank will be more complicated, and plastic deformation and resonance will easily occur. Therefore, finite element analysis is required for the strength, design and installation of the heating water tank itself to ensure its reliability under different working conditions. This article will use three-dimensional finite element software to simulate and analyze the basic strength of the PTC heating water tank of electric vehicles. It mainly includes two aspects: (1) In order to avoid resonance of the heating water tank during the driving process of the car, the PTC heating water tank is performed as a whole Modal analysis, extract the natural frequency of the heating water tank; (2) Simulate the impact of the heating water tank in the PTC water heater system during the driving process of the car, in the X, Y, Z three directions respectively to the overall heating water tank Apply corresponding acceleration to observe the static response of the heating water tank as a whole. The strength and safety of the heating water tank are evaluated through modal analysis and static analysis, which provides a certain reference for detailed design. Analysis process 1.1 The establishment and simplification of the finite element model The analysis object of this article is the PTC heating water tank. The water tank can be roughly divided into upper shell, upper shell insert, lower shell, grounding harness, water inlet pipe, water outlet pipe and electrical signal interface Among them, there are fixed positions for the heating water tank and the whole vehicle to be installed in the four oval wire frames. The installation method is fixed by bolt locking, and there is a copper insert in each of the four mounting holes. The positions marked by the six rectangular wire frames are the installation and fastening points of the upper and lower housings, which are also fixed by bolt locking. Before the finite element analysis of the heating water tank, in order to facilitate the analysis, the model needs to be simplified, and the following assumptions are made for the entire physical problem: (1) The grounding harness, electrical signal interface, water inlet and outlet pipes and other structures in the heating water tank are ignored; (2) Upper and lower shells It is fixed by bolt structure; (3) Assuming that the well-fixed upper and lower shells are a complete structure, ignoring the bolt structure, bind the upper and lower shells through surface contact; (4) Completely fix the inner surfaces of the 4 mounting foot bolt holes.