Piezo stack temperature estimator

摘要

The invention relates to a method of estimating the temperature of a piezoelectric actuator body for controlling the operation of a fuel injector mounted within an engine housing and supplied with fuel from a high pressure fuel pump. The piezoelectric actuator body is housed within a volume of fuel. The method comprises determining a temperature (T_{-INJ IN}, T_{-PUMP IN}) of fuel upstream of the fuel volume, determining a temperature (T_-CYL) of the engine housing, and estimating a temperature (T_{-STACK STEADY STATE}; T_{-STACK DYNAMIC}) of the piezoelectric actuator body based on the upstream temperature (T_{-INJ IN}, T_{-PUMP IN}) and the temperature (T_-CYL) of the engine housing. By considering the heat transfer between the piezoelectric actuator body, the injector and fuel within the volume, and the heat transfer due to fuel flow through the volume for an injection, the temperature of the piezoelectric actuator body can be estimated by modelling or mapping.