Torque of the town
From car ashtrays to toilet seats and substantial pieces of office furniture, viscous gels are key to a family of devices that control or modify the motion of products
. Japanese manufacturer Sugatsune Kogyo lumps them all together as “torque dampers”. And it’s all delivered at low cost.
The smallest units are made of plastic, with or without a gear attached to the shaft, and incorporate an internal shaft equipped with a vane running round the inside of gel-filled cylinder. By making the vane compliant, it is possible to ensure it lies down, resulting in little to no resistance to motion when the shaft is rotated in one direction. Conversely, when the shaft is rotated in the other direction, the vane stands up, ensuring maximum resistance as it pushes through the gel. It then functions as a one-way clutch, slipping at a much higher torque in one direction than the other.
The devices can be made to damp motion either in one or both directions. Damping torques range from 10gf-cm (0.001N-m) to 1500gf-cm (0.15N-m). Applications include retractable car ashtrays, loading trays for DVD players, arm rests, camcorders and mobile phone lids.
Slightly stronger cylindrical units have been designed for, among other things, damping the descent of toilet seats and lids. These push gel through an orifice and damp in one direction only. Damping torques are from 15 to 40 Kgf-cm (1.5 to 4N-m). The company also makes one-way rotary disk dampers, with damping torques from 20 to 110 Kgf-cm (2 to 11N-m); two-way disk dampers, with damping torques from 20 to 87 Kgf-cm (2 to 9 N-m); and an adjustable vane damper, one way or two way, with a maximum damping torque of 100kgf-cm (10N-m). The damping torque is controlled by the size of the vane in the damper body. Applications include home and office furniture, and printer and copier covers.
