Search Results

Attempts were made to measure knocking phenomenon by an optical method, which is free from influences of mechanical noises and is allowing an easy installation to an engine. Using a newly developed high durability optical probe, the light intensity of hydroxyl radical component, which is diffracted from the emitted light from combustion, was measured. The intensity of this emission component was measured at each crank angle and the maximum intensity in a cycle was identified. After that, the angular range in which the measured intensity exceeded 85% of this maximum intensity was defined as “CA85”. When a knocking was purposely induced by changing the conditions of the engine operation, there appeared the engine cycles that included CA85 less than a crank angle of 4 degrees. The frequency of occurrence of CA85 equal to or less than 4 degrees within a predetermined number of engine cycles, which can be interpreted as a knocking occurrence ratio, was denoted as “CA85-4”.

In the real site of engine development, new means are required for optical measurements under a wide variety of conditions including high-loaded operation. We have accordingly developed the new optical probe having less restriction when installing onto the engine as well as having high durability. The shape of connector end of newly developed optical probe that fits to the engine is interchangeable with the M5 sensor used for in-cylinder pressure measurement. The optical module of the optical probe can also be installed in the M10 spark plug or the M8 glow plug. The durability of the newly developed optical probe is; heat up to 400°C, pressure up to 25 MPa, and vibration up to 50 G. The durability of the optical probe was assessed using the engines of commercially available motorcycles. The 110 cm3 engine was used for the time-wise assessment. The 150 cm3 engine was used for the environment-wise assessment. Either one is a single cylinder engine.