US Patent 10508721 Load-adjustable constant-force mechanisms

A compliant crank slider with adjustable constant-force output. Constant-force mechanisms (CFM) are used to maintain a constant output reaction force throughout a large range of compressive motion. The invention improves on existing CFM by introducing a second degree of freedom that adjusts the mechanism's output without changing its kinematic structure. This second degree of freedom is the rotation of a compliant beam about its longitudinal axis as it is constrained to the initial plane of bending. The resulting change in the beam's stiffness allows for adjustment to a specifiable range of constant-force outputs.