New Electric Axle Disconnect Promises 10-20 Percent Boost in EV AWD Range

Drivers increasingly demand all-wheel-drive security, but carmakers struggle to minimize the impact that has on vehicle efficiency. This issue is particularly acute for EVs, which have less stored energy to spare than combustion vehicles carry in their fuel tanks.

Amsted Automotive has introduced an electro-mechanical e-axle disconnect system dubbed the Dynamic Controllable Clutch that is optimized for the task of disconnecting the unneeded drive axle of AWD EVs. Combustion-powered vehicles commonly employ hydraulic axle disconnect systems, but the advantages of electric drivetrains include their simplicity and absence of liquids, so adding a hydraulic system would negate those benefits.

Because the DCC magnetically locks in its engaged and disengaged states, it requires no energy to maintain those states, according to the company. Meanwhile, eliminating the parasitic drag of the unneeded axle yields energy savings that contribute to a 10 to 20 percent increase in driving range compared to a full-time AWD system. When the disengaged axle needs to contribute power for traction, the DCC brings it back online in just 20 milliseconds.

“Traditional clutches, such as hydraulic or even electrically actuated dog clutches, dramatically increase power losses and system mass,” explains Amsted in a white paper posted on the company’s web site. “They also prove to be difficult to calibrate and are not the best solution for the instantaneous actuation desired by consumers. EV powertrains favor mechatronic solutions that are easily calibrated and draw very little power for engagement and holding state.”

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Sounds simple enough, but it is hard to get the necessary clamping strength to withstand the fierce torque delivered by electric motors. “One main challenge with the E-axle Disconnect project was the extremely high strength requirements of electric vehicle drivetrain as compared to traditional internal combustion engine powertrain designs,” observed Amsted Automotive Senior Business Development Engineer Dustin Finn.

Amsted engineers were able to overcome that challenge with continuous development, Finn added. “Overall, we were able to increase the disconnect strength by three times from the start of the program without changing the design.”

This accomplishment was made even harder to achieve by the OEM customer’s short deadline, he added. “To meet the aggressive milestone dates, the development phase of the disconnect system ran parallel with the production-level tooling phase,” Finn explained. “We overcame this with maximized collaboration that resulted from a strong customer relationship. This resulted in agile development of the new technology while meeting the customers very aggressive timeline.”

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Amsted Automotive Group was formed in 2021 from the merger of Means Industries Inc., SMW Manufacturing, and Burgess-Norton Mfg. Co., Inc. to global presence with 21 facilities in North America, Europe, and Asia.