Patent ID: 9021791
Filing Date: 2015-05-05
Classification: F01N,F02D,Y02T

Abstract:
1. A method for diagnosing a metering valve that is configured to control a metering rate for metering a reagent into an exhaust gas region of an internal combustion engine, the method comprising: providing, by a pump, a reagent to the metering valve at a reagent pressure value based on a pulse width modulated (“PWM”) pump actuation signal; determining, by a control unit, the PWM pump actuation signal; determining, by the control unit, a reagent filling level of a selective catalytic reduction (“SCR”) catalytic converter; comparing, by the control unit, the reagent filling level with a first threshold value; storing, by the control unit, a first value of the PWM pump actuation signal in a memory if the reagent filling level is less than the first threshold value; increasing, by the metering valve, the metering rate after storing the first value of the PWM pump actuation signal; storing, by the control unit, a second value of the PWM pump actuation signal in the memory upon expiration of a time period following increasing the metering rate; and comparing, by the control unit, a difference between the first value and the second value of the PWM pump actuation signal with a second threshold value.