Patent ID: 7930093

Claim:
A method for filtering a disturbed cylinder pressure signal from a cylinder in an internal combustion engine, wherein during one operating cycle of the engine, the disturbed cylinder pressure signal is affected by multiple disturbance variables occurring during specific time periods in the operating cycle, the multiple disturbance variables including multiple different types of disturbance variables, the method comprising the steps of: maintaining assignments of different filter types to the different types of disturbance variables, each assignment comprising an assignment of one of the different filter types to one of the different types of disturbance variables, such that at least two different filter types are assigned to at least two different types of disturbance variables, for each disturbance variable in the pressure signal occurring during the operating cycle: determining the type of the disturbance variable and applying the type of filter that is assigned to that type of disturbance variable in order to filter the disturbance variable from the pressure signal, such that different filter types are used to filter different disturbance variables during the operating cycle, and controlling the timing of applying the filters to the multiple disturbance variables in the cylinder pressure signal as a function of a crankshaft angle and predetermined time windows corresponding to the disturbance variables.