Abstract
The GDI (Gasoline Direct Injection) injector is influenced by electro-magnetic-thermal coupling, and has strong nonlinearity and coupling. Temperature rise greatly impacts the performance of the GDI injector and makes the ECU of the engine difficult to control fuel injection quantity accurately. According to the coupling relationship of electric, magnetic and thermal subsystems of the GDI injector, the physical model of coupled process was established. The energy loss and transformation of the GDI injector in work process was explored, and revealed that the energy loss in electromagnetic conversion was a key factor to cause the GDI injector temperature rise. The energy loss coming from electromagnetic conversion was regarded as heat source. The temperature field of the GDI injector contains heat conduction and thermal radiation was analyzed based on the finite element theories. By using the ANSYS software to simulate multiple physical fields of the GDI injector, and then experiment method to verify the simulation results, distribution characteristics of temperature field and variations of temperature rise effect on the performance of the GDI injector was analyzed. The results show that, higher temperature rise is concentrated on coil and core part and with the higher temperature rise the response time of the GDI injector get longer, the fuel injection quantity becomes less. The value and pulse width of the holding current I have great impact on the GDI injector performance and temperature rise.
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