Shape Memory Alloy Actuators for Adjustable Lumbar Support Force

The patent replaces conventional mechanical adjustment mechanisms with shape memory alloy (SMA) actuators that use thermal-mechanical coupling to adjust lumbar support force. The SMA members transform thermal energy into mechanical contraction, enabling electrically controlled adjustment of the lumbar support element, thereby improving user control while maintaining relatively simple device architecture.

The invention changes the physical state of the shape memory alloy material through temperature variation to alter its mechanical properties. By heating the SMA members above their transformation temperature, they contract to apply lumbar support force; cooling them returns them to their original state. This parameter change enables dynamic control of support force without complex mechanical linkages.

The system employs periodic or intermittent activation of the shape memory alloy actuators rather than continuous operation. The control module can cycle the SMA members between activated and deactivated states, providing lumbar support force only when needed based on user requirements or detected postures, thereby reducing overall energy consumption while maintaining ergonomic comfort during active periods.

The invention utilizes the phase transition properties of shape memory alloys, which undergo reversible transformation between martensite and austenite phases at specific temperatures. This phase transition enables the material to generate significant mechanical force during contraction, providing effective lumbar support with relatively low energy input compared to conventional actuators that would require continuous power maintenance.