Force analysis of the apex seals in the Wankel rotary compressor including the influence of fluctuations in the crankshaft speed

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This paper derives equations for the radial and transverse components of the acceleration of an apex seal in the rotor of a Wankel rotary compressor. Then the equations are modified to include the effects of two cyclic fluctuations in the crankshaft speed during start-up and a simple harmonic fluctuation in the nominal operating speed. Following this, we investigate a dynamic force analysis of the seal including the friction forces between the tip of the seal and the housing and between the side of the seal and the rotor. The investigation shows that the effects of the friction between the side of a seal and the rotor are insignificant. Therefore, ignoring this friction, plots are presented for the housing force and the normal force as a function of the crank position and the fluctuation in the operating speed for a specified trochoid ratio. The plots show that realistic values of the fluctuation in the operating speed do not have a significant effect on the forces acting on a seal and can, therefore, be safely neglected. Plots are also presented for the two forces, for a specified fluctuation in the operating speed, against a specified range of the trochoid ratio and different positions of the crank. Finally, for a specified trochoid ratio, the two forces are plotted against several values of start-up time as the compressor accelerates to the nominal operating speed with a constant acceleration. © 1997 Elsevier Science Ltd. All rights reserved.

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Mechanism and Machine Theory