On the Ineffective Lift of Poppet Valves in Internal Combustion Engines

抄録

To examine the effects of various factors on the ineffective angle or the corresponding valve lift, the authors carried out some experiments with two model pieces of piston head and a regular one in an air-cooled, single cylinder, four-stroke cycle engine. A summary of the results is as follows; a) If the ineffective valve lift be used instead of the ineffective angle, it is not necessary at all to consider the values of tappet clearance and the kinds of valve lift curve. b) It is possible to estimate the ineffective lift not only by the measurement of air flow, but also by the analysis of pressure diagrams. c) The ineffective lift increases with the engine speed, but decreases as the pressure difference between suction and exhaust ports increases. d) The minimum value of the ineffective lift remains constant irrespective of the engine speed and the pressure difference.