GM’s working on a clutch for an electric car transmission

Electric cars don’t require multiple gears, but they still have transmissions. And General Motors is working on a way to make them better.

A patent filing from the automaker detailing a new type of clutch actuation for EV transmissions recently surfaced. It was published by the United States Patent and Trademark Office (USPTO) May 16, 2024, and originally filed by GM November 10, 2022.

2024 Chevrolet Blazer EV RS

In this document, GM discusses using a hydraulic actuator to operate a clutch in automatic transmissions used in electric cars. A controller would vary the pressure of the fluid in the actuator, which in turn would move a piston that would open or close the clutch depending on what the controller determines is best in a given scenario.

This setup would be simpler than conventional automatic transmissions, something enabled by an electric motor’s need for fewer gearshifts, GM states in the patent filing. It would also avoid “instabilities at the electric motor” inherent in other types of clutch actuation, according to GM.

2024 Cadillac Optiq

A clutch setup like this could be used to decouple a motor from a set of drive wheels to improve efficiency. That also seems like a more probable application, as most current EVs don’t have multi-speed transmissions, taking full advantage of the instantly available torque of electric motors. The Porsche Taycan has a 2-speed gearbox, and Stellantis has patented a 2-speed transmission for off-road EVs.

Ford and Toyota have both patented manual transmissions for electric cars, which would allow drivers to control shifting and clutch actuation even though it’s mechanically unnecessary. Stellantis has also patented simulated shift points for EV transmissions, achieved by altering motor torque rather than through means of a physical shifter or clutch.