Control apparatus for a diesel exhaust fluid injector

摘要

A control apparatus is disclosed for a diesel exhaust fluid injector located in an exhaust pipe of a diesel internal combustion engine. The control apparatus includes an electronic control unit configured to: energize a solenoid of the injector to perform a diesel exhaust fluid injection; determine an electric voltage value indicative of the electric voltage applied to the injector solenoid during the diesel exhaust fluid injection; determine an electric current value indicative of the electric current flowing through the injector solenoid during the diesel exhaust fluid injection; calculate an electric resistance value of the injector solenoid as a function of the determined electric voltage value and the electric current value; and estimate an injector temperature value as a function of the calculated electric resistance value.

主权项

1. A control apparatus for an exhaust fluid injector located in an exhaust pipe of an internal combustion engine and operable for exhaust fluid injection, wherein the control apparatus comprises an electronic control unit configured to:
energize a solenoid of the exhaust fluid injector to perform an exhaust fluid injection using a pulse width modulation (PWM) strategy or a peak to hold strategy communicated from the electronic control unit (ECU) to the exhaust fluid injector, wherein the ECU is configured to operate the exhaust fluid injector; determine, by the ECU, an electric voltage value (Vcoil) indicative of an electric voltage applied to the solenoid during the exhaust fluid injection, wherein the exhaust fluid injector comprises the injector solenoid; determine an electric current value (Icoil) indicative of an electric current flowing through the injector solenoid during the exhaust fluid injection; calculate an electric resistance (Rcoil) value of the injector solenoid as a function of the determined electric voltage value (Vcoil) and the electric current value (Icoil); and estimate an exhaust fluid injector temperature value (Tcoil) as a function of the calculated electric resistance value (Rcoil); determine an exhaust temperature value (Texh) of temperature of the exhaust gas flowing along the exhaust pipe during the exhaust fluid injection; determine an exhaust mass flow rate value (Qexh) indicative of a mass flow rate of the exhaust gas flowing along the exhaust pipe during the exhaust fluid injection; estimate an exhaust gas contribution (ΔTexh) to an exhaust fluid injector temperature as a function of the determined exhaust temperature value (Texh) and exhaust mass flow rate value (Qexh); correct an estimated value (Tcoil) of the exhaust fluid injector temperature with the exhaust gas contribution (ΔTexh); and activate a cooling phase of the exhaust fluid injector when an estimated value of the exhaust fluid injector temperature (Ttip) exceeds a predetermined threshold value (Tth), by:
determining a quantity of diesel exhaust fluid (DEF) required to cool the exhaust fluid injector; andinjecting the quantity of DEF, by the exhaust fluid injector, by energizing the exhaust fluid injector using the PWM strategy or the peak to hold strategy communicated from the ECU to the exhaust fluid injector.