Patent ID: 8468810
Filing Date: 2013-06-25
Classification: F01N,Y02A,Y02T

Abstract:
1. An NOx injection system for treating a vehicle exhaust system comprising: an injector for injecting a select material into the vehicle exhaust system and including an electrical coil; and an injector firing control circuit electrically connected to the injector for driving the coil comprising a switch selectively coupling a supply to the electrical coil, a flyback diode connected across the electrical coil and an impedance element connected in series with the flyback diode to increase reverse voltage to increase injector turn off response, wherein the injector firing control circuit comprises a voltage source generating a first select voltage level, a voltage storage circuit and a switching circuit, comprising the switch, operatively coupling the voltage source and the voltage storage circuit to the electrical coil, the switching circuit operating in an on mode to fire the injector and in an off mode to turn off the injector, the voltage storage circuit being charged during the off mode and in the on mode both the voltage source and the voltage storage circuit being electrically connected to the injector whereby the electrical coil is initially driven by a second select voltage level higher than the first select voltage level and thereafter by the first select voltage level.