Accurate Detection of Engine Knock

Engine knock is caused by the auto-ignition of the fuel and air mixture compressed in the cylinder before normal combustion is complete. A vehicle with engine knock will quickly suffer engine damage, yet operating at conditions far from the knock limit will quickly reduce fuel economy. Because engine knock typically generates high frequency vibrations in the engine, it can be measured by accelerometers mounted on the engine block. The intensity of the engine knock varies from cycle to cycle and can lead current knock detection systems to underestimate the level of knock resulting in possible engine damage or overestimate the level of knock resulting in fuel economy losses.

The solution to accurate engine knock measurement lies with statistical characterization. The invention is a software algorithm that capitalizes on current Engine Control Unit (ECU) hardware to fit the cycle-cycle knock intensities to a probability density function. The statistical characterization is more accurate for both stationery and non-stationery detection of engine knocks. The model was developed using a standard 3.0 liter, V-6 internal combustion engine.

Minimizing engine knock provides many advantages including reduced fuel consumption, reduced engine noise and improved tolerance to alternative fuels including biofuel blends. The developed software algorithm improves the robustness of existing ECU hardware with a more accurate measuring system. This calculation improves performance and extends internal combustion engine life while being applicable to most ECUs on the market.

Exclusive and nonexclusive license terms are available on this innovation (U.S. Patent No. 7,415,347, issued January 2008). For more information contact John Diebel in the Office of Innovation and Industry Engagement, 906-487-1082.