1-D Modellering av Piezoelektrisk Injektor
A piezoelectric injector was modeled, in this Master Thesis Project which was carried out at Scania CV AB in Södertälje, in GT-Fuel. GT-Fuel is simulation program from Gamma Technology.The simulation model for the piezo injector was divided into a hydro-mechanical system and an electrical system (Piezoelectric element). First the hydro-mechanic model was duplicated from Advance Continuous Simulation Language model (ACSL). The simulation results were then compared to the ACSL, to verify that the hydro-mechanical system was modeled correctly. The simulation results for the electrical model were also compared with a Simulink model. Comparison shows that the simulation results correspond with results from other simulations.The piezoelectric element in GT-Fuel is a relatively simple model, not all of the electrical circuits in the element are covered. This limitation gave an inaccurate value of needle displacement, that is to say it generates too large needle displacement. The piezoelectric element can be modeled in GT-Fuel by using a couple of functions in order to model electrical circuit. This would take time so therefore some limitations have been made. Another solution would be to couple GT-Fuel to Simulink, but this was difficult to achieve.A study has been made around some significant parameters (for instance; Injector Body volume, orifice diameter and clearance diameter), which affect injector performance. The results shows that by increasing the clearance diameter affected the needle lift, which caused the needle to close earlier. Decreasing the orifice diameter resulted in changing the needle profile. In other words, the needle closes slower because it takes time to refill the Control Chamber. Increasing the Injector Body volume did not affect injector performance but it gave a better profile for the needle.