Synthesis and baseline testing of a digital pulse-width-modulated clutch

The switch-mode continuously variable transmission is the mechanical analog of a DC-DC boost converter circuit and allows coupling a high speed flywheel to a mechanical load. The system requires a high-frequency clutch with a variable duty ratio and low slip during engagement and disengagement. In this paper, the synthesis and baseline testing of a novel digital clutch for this application are presented. The custom clutch design utilizes a double dwell axial cam with a profile that varies with radius. The duty cycle of the clutch is controlled through positioning the radial location of three translating followers, connected through a linkage. The axial clamping force of the clutch is generated through designed deflection of the system components and springs in series with the cam followers. Through baseline testing, the clutch was operated at angular velocities up to 45 rad/s, creating clutch switching frequencies up to 22 Hz. The average clutch efficiency at 20% duty cycle was 55%, yet the efficiency is highly dependent on the duty cycle and can be improved in future testing.