GM Files Patent To Develop Adaptive Suspension Springs

Getting a good balance between suspension performance and comfort is the reason for suspensions with adjustable spring rates, letting the user tweak the rate to specific conditions between uses. Now, GM has filed a patent for an adaptive suspension system that can change the rate on the fly.

The United States Patent and Trademark Office (USPTO) assigned the patent application by GM for “Variable Suspension Spring Rates Using Magnetorheological Fluid” patent number US 2024/0367473 A1. The application was originally filed on May 5^th, 2023 and was published on November 7^th, 2024, with two U.S. engineers – Brian K. Saylor and Robert P. Marble – and one Canadian – Christopher J. Mettrick – as the inventors.

The patent application describes a suspension system in which an inner spring core is surrounded by a sealed spring seat filled with magnetorheological fluid, with a second spring surrounding this in turn. The viscosity, or resistance to a change in shape, by the magnetorheological fluid, can be altered by activating nearby electromagnets that act on the metallic particles in the fluid.

The system, if it works as intended, will send a signal to a suspension control module to change the resistance or rate of the springs during vehicle operation. This will activate the electromagnets and alter the viscosity of the magnetorheological fluid, immediately changing the suspension spring rate without the need for mechanical adjustments.

These adaptive suspension springs use technology already used in dampers, with a silicon oil holding metallic particles in suspension, but include the novel feature of enabling adjustment of spring travel using controls in the vehicle, altering the balance between performance and comfort in real time as driving conditions change. Energizing the fluid creates a stiffer suspension while reducing electromagnetic energy or switching it off loosens the spring.

The patent filing envisions using automatic systems to change spring rate for different wheels based on detected driving conditions. Going over a sharp bump could trigger a brief stiffening of the spring in the affected wheel, the return to a normal comfort driving level when back on smooth pavement. Sensors could also detect road hazards like potholes immediately ahead and alter the spring rate to lessen the jarring effect on the vehicle and occupants.

The adaptive suspension system builds on existing GM technology and would have wide applications across The General’s model range. More upscale models such as the Chevrolet Corvette and the Cadillac Escalade are obvious potential candidates, but the tech would be theoretically applicable across the whole lineup to provide a smoother and more consistent ride.