Abstract
The paper presents direct measurement of in-cylinder friction from a single cylinder motocross race engine under motored conditions and compares the same with a new analytical predictive method. These conditions are encountered in piston–cylinder system with the application of cylinder deactivation (CDA) technology, which is a growing trend. The analytical method takes into account the various regions within instantaneous contact of compression ring–cylinder liner, including lubricant film rupture, cavitation zone and the subsequent lubricant film reformation. The analysis also includes the effect of boundary friction and lubricant rheology. The predictions and direct measurements of cyclic friction show good agreement and indicate dominance of viscous friction under the investigated engine running conditions. In particular, it is shown that the compression ring contribution to in-cycle friction is most pronounced in the region of high cylinder pressures because of combined Poiseuille friction and some boundary solid interactions. The combined experimental-analytical approach has not hitherto been reported in literature.
Highlights
The engine friction consumes around 7–8% of generated combustion energy in an internal combustion (IC) engine
The paper presents direct in situ measurement of incylinder friction using a devised floating liner system
The difference in the cyclic frictional traces with and without the presence of the compression ring provided an assessment of incycle friction contributed by the compression ring
Summary
The engine friction consumes around 7–8% of generated combustion energy in an internal combustion (IC) engine. The parameters a, c, r and b represent the contact inlet, lubricant film rupture point (onset of cavitation region), lubricant reformation boundary and the outlet edge of the ring face width, respectively (see Figure 3).
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Schedule a callMore From: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
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