Linear actuation drive mechanism for power-assisted chairs and base thereof

摘要

A chair including a power-assisted linear actuation drive mechanism having a cam guide which is linearly movable upon retraction of a shaft for selectively actuating a lift and tilt linkage mechanism, and for causing forward lifting and tilting movement of the chair when a motor of the mechanism is operated in a first direction. Extension of a shaft in a second opposite direction acts to lower the chair to a normal seating position. Continued extension in the second direction causes a first cam block pivotably mounted to the cam guide to engage a first follower assembly for causing extension of a leg rest assembly. Further extension in the second direction causes a second cam block pivotably mounted to the cam guide to engage a second follower assembly for causing reclining movement of the chair. This sequential operation of the leg rest assembly and the reclining linkage are independent and may be easily disabled to selectively eliminate either of the features. In an alternative preferred embodiment a chair base includes a lift arm for providing additional vertical lift to the front portion of the chair base when the chair is raised to its lifted position. In an alternative preferred embodiment, the chair base includes a brake assembly, wheel assemblies, and various structural improvements to the power-assisted drive mechanism.