FUNCTIONAL MONITORING OF AN INJECTION SYSTEM

摘要

An injection system (115) for injecting a liquid medium (120) into an exhaust gas system (100) comprises a positive displacement pump (125) for delivering the medium (120), a drive device (130) for the positive displacement pump (125), a control device (135) for controlling the drive device (130) in a manner dependent on a pressure of the delivered medium (120), and a valve (140) for injecting the delivered medium into the exhaust gas system, wherein a malfunction determination of the injection system (115) comprises the steps of determining a first delivery volume of the positive displacement pump (125) per movement cycle of the drive device (130) with regard to a first preceding time period, determining a second delivery volume of the positive displacement pump (125) per movement cycle of the drive device (130) with regard to a second preceding time period, wherein the first time period is multiple times longer than the second time period, and there is a malfunction if the second delivery volume differs from the first delivery volume by at least a predefined fraction.