Change of spring force by means of levers

What is this patent about?

’750 is related to the field of vehicle suspension systems, specifically those employed in vehicle seats or cabs to isolate occupants from chassis vibrations. Traditional systems often rely on complex pneumatic springs and dampers that require intensive maintenance and sophisticated control logic to adapt to different occupant weights. The background context suggests a need for a more robust, mechanically simple solution that can provide consistent vibration decoupling without the high costs associated with active air-spring management.

The underlying idea behind ’750 is to modulate suspension characteristics by using a deflection lever to translate the movement of a scissors-type frame into a specific spring response. Rather than mounting a spring directly between the seat base and the frame, the invention introduces a mechanical intermediary that alters the effective lever arm and force direction. This allows the system to maintain an optimal vibration frequency for different loads by simply adjusting the geometry of the connection between the spring and the scissor arms.

The claims of ’750 focus on a spring system comprising a scissors-type frame where a spring element is coupled to a deflection means that is directly attached to one of the scissor arm segments. A critical feature of the independent claim is that the angle between this deflection lever and the scissor arm remains fixed during normal operation, while the spring itself spans between this lever and a second, separate scissor arm. This specific geometry ensures that the force exerted by the spring is influenced by the momentary height and orientation of the frame segments.

In practice, the invention works by utilizing the rotating motion of the scissor arms to compress or extend a spring—such as a gas, coil, or rubber spring—via the deflection lever. Because the lever is fixed at a specific angle to the arm, the effective torque generated by the spring changes dynamically as the seat moves through its vertical travel. This mechanical arrangement allows for a compact, horizontal spring placement that can still provide the necessary vertical resistance to support a driver, effectively decoupling the seat from high-frequency chassis oscillations.

This approach differs from prior solutions by eliminating the need for complex external dampers and active air controls to handle weight variations. By adjusting the locked position of the deflection means relative to the scissor arm, the system can be tuned for different driver weights, shifting the force-travel curve to ensure a consistent ride quality. The integration of the spring directly into the frame geometry via a lever provides a more durable and cost-effective mechanism that achieves variable suspension rates through pure mechanical kinematics.