Input Torque Balancing Using a Cam-Based Centrifugal Pendulum: Design Procedure and Example

Input torque balancing is a well known way to reduce drive speed fluctuations in high speed machinery and combustion engines. This paper introduces a cam-based centrifugal pendulum (CBCP) and a design procedure for it which results in quasi perfect balancing of inertial torques for any drive speed. The CBCP combines the centrifugal pendulum vibration absorber, well-known in mechanical vibration literature, with a torque balancing principle well-known in mechanism literature, that is, the use of cams to generate arbitrary torques. For given design parameters (such as the link lengths and link inertial parameters), the cam design is governed by a nonlinear, second-order, explicit differential equation. This differential equation is numerically solved by reformulating it as a nonlinear least squares problem. The design parameters themselves are determined by means of an optimization problem, the goal of which is to minimize the (constant) equivalent inertia of the combined system, consisting of the original mechanism to be balanced and the CBCP. Application of the CBCP to torque balance a high-speed, purely inertial cam-follower mechanism, driving the sley of a weaving loom, shows that the optimization results in a compact and technologically feasible mechanism.