Abstract:To achieve the realtime monitoring of wear condition and the diagnosis of cylinder and piston ring defects,taking the cylinder and piston ring reciprocating machine as the research object,the acoustic emission signal characteristic parameters along with the change of crank angle in one cycle between cylinder and piston ring were studied based on acoustic emission technology,and the friction characteristic signals were analyzed.Results show that acoustic emission signals of cylinder and piston ring in one cycle change as a ‘double hump’ shape.The strength of acoustic emission signal at top dead centre(TDC)and bottom dead center(BDC)is the weakest,and it is the strongest around the midpoint of stroke.With the increase of rotational speed,acoustic emission characteristic parameters RMS and absolute energy are increased gradually,the increasement is smaller near the TDC and BDC,and bigger near the midpoint.Along with the increase of load,at low speeds,RMS and absolute energy present the trend of ascend,but the increasement is decreased gradually;while at high speed,RMS and absolute energy present the change trend of first increases and then decrease.