Patent ID: 7433776

Claim:
A method for quantizing fuel dilution of a supply of engine motor oil in a lubrication system of an internal combustion engine due to post-injection of fuel into a cylinder of the engine that occurs after a main injection to create rich exhaust leaving the cylinder, the method comprising: in a data processing system associated with the engine, executing an algorithm for a) calculating a quantity of post-injected fuel that is retained in a film of engine motor oil on a wall of the cylinder and that, as a consequence of such retention and continuing operation of the engine, is returned to the engine motor oil supply, the algorithm comprising processing various data including data indicative of the quantity of post-injected fuel, data indicative of in-cylinder pressure at some point in the engine cycle that bears on the quantity of post-injected fuel retained in the film, data indicative of in-cylinder temperature at some point in the engine cycle that bears on the quantity of post-injected fuel retained in the film, and data indicative of engine speed, and b) using the calculated quantity of post-injected fuel that is retained in the film to quantize fuel dilution of the engine motor oil supply.