Piezo stack temperature estimator

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 being located within a fuel volume that receives fuel from the high pressure fuel pump, in use, the method comprising:

• determining a first temperature of fuel upstream of the fuel volume;
• determining a temperature of the engine housing;
• estimating a temperature of the piezoelectric actuator body based on the first temperature and the temperature of the engine housing;
• determining a pump outlet temperature of fuel at an outlet of the high pressure fuel pump;
• determining the injector inlet temperature based on the pump outlet temperature;
• and
• determining the injector inlet temperature based on the pump outlet temperature and a predetermined time constant representative of at least one system characteristic between the pump outlet and the injector inlet;
• wherein the step of determining the first temperature includes determining a temperature of fuel at an inlet of the fuel injector.

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 being located within a fuel volume which receives fuel from the high pressure fuel pump, in use, the method comprising:

• determining a first temperature of fuel upstream of the fuel volume;
• determining a temperature of the engine housing;
• estimating a temperature of the piezoelectric actuator body based on the first temperature and the temperature of the engine housing;
• and
• estimating a steady state temperature of the piezoelectric actuator body by means of a mapping function which receives inputs of the injector inlet temperature, the temperature of the engine housing, an engine speed condition and a fuel delivery condition;
• wherein the step of determining the first temperature includes determining a temperature (T13 INJ IN) of fuel at an inlet of the fuel injector.

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 being located within a fuel volume which receives fuel from the high pressure fuel pump, in use, the method comprising:

• determining a first temperature of fuel upstream of the fuel volume;
• determining a temperature of the engine housing;
• estimating a temperature of the piezoelectric actuator body based on the first temperature and the temperature of the engine housing;
• and
• determining a pressure of fuel at an outlet of the high pressure fuel pump and estimating a steady state temperature of the piezoelectric actuator body by means of a mapping function which receives inputs of the pump inlet temperature, the temperature of the engine housing, the pressure of fuel at the high pressure fuel pump outlet, an engine speed condition and a fuel delivery condition:
• wherein the step of determining the first temperature includes determining a pump inlet temperature at an inlet to the high pressure fuel pump.

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 being located within a fuel volume which receives fuel from the high pressure fuel pump, in use, the method comprising:

• determining a first temperature of fuel upstream of the fuel volume;
• determining a temperature of the engine housing;
• estimating a temperature of the piezoelectric actuator body based on the first temperature and the temperature of the engine housing;
• and
• estimating a dynamic temperature of the piezoelectric actuator body by means of a thermal model of heat transfer between the piezoelectric actuator body, the injector body and the fuel volume, wherein the thermal model receives inputs based on injector inlet temperature and the temperature of the engine housing;
• wherein the step of determining the first temperature includes determining a temperature of fuel at an inlet of the fuel injector.

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 being located within a fuel volume which receives fuel from the high pressure fuel pump, in use, the method comprising:

• determining a first temperature of fuel at an inlet of the fuel injector,
• determining a temperature of the engine housing,
• estimating a temperature of the piezoelectric actuator body based on the first temperature and the temperature of the engine housing,
• determining the injector inlet temperature based on the pump outlet temperature and a predetermined time constant representative of at least one system characteristic between the pump outlet and the injector inlet, and
• controlling the piezoelectric actuator body on the basis of the estimated temperature.

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 being located within a fuel volume which receives fuel from the high pressure fuel pump, in use, the method comprising:

• determining a pump inlet temperature at an inlet to the high pressure fuel pump,
• determining a temperature of the engine housing,
• estimating a temperature of the piezoelectric actuator body based on the pump inlet temperature and the temperature of the engine housing,
• determining the injector inlet temperature based on the pump outlet temperature and a predetermined time constant representative of at least one system characteristic between the pump outlet and the injector inlet, and
• controlling the piezoelectric actuator body on the basis of the estimated temperature.