Audi patents new range-extender system that drops one motor for quattro AWD

Patent explores a leaner architecture

Audi is investigating a range-extender electric vehicle (EREV) layout that would remove a standalone generator from the powertrain. The firm confirmed there is no production vehicle, platform or timeline tied to the concept yet.

Going without one extra motor gives the company room to trim parts, wiring and installation space, which should reduce material cost and weight. The trade-off is that managing Audi’s signature quattro all-wheel-drive system becomes noticeably more complex.

How the system is meant to work

Under normal operation, the high-voltage battery supplies the primary drive motor, which powers one axle. When four-wheel drive is required, a second drive motor takes care of the other axle.

In a typical two-wheel-drive plug-in range-extender setup, the vehicle carries one generator and one drive motor. A conventional four-wheel-drive range-extender usually adds another drive motor and keeps the generator separate. Audi’s proposal removes that dedicated generator entirely and links the internal-combustion engine to the second drive motor through a clutch assembly.

With a healthy state of charge, both motors can propel the wheels and recover energy during braking. As the battery depletes, a controller engages the clutch so the engine mechanically drives the second motor, which then acts as a generator to replenish the pack.

In certain conditions the patent also describes the engine delivering power directly to the wheels through the rear motor’s transmission path, further blurring the line between a pure range extender and a conventional plug-in hybrid.

Cost savings versus control challenges

The chief attraction is economics. Removing a motor also cuts associated power electronics, harness length and packaging volume. In theory, fewer components should simplify manufacturing and lower the vehicle’s bill of materials.

However, canceling that motor forces the introduction of clutches, linkages and additional mechanical hardware, making the overall architecture more intricate rather than simpler.

The real engineering headache centers on quattro functionality. When the second motor is being used as a generator, it cannot simultaneously provide traction to its axle, so four-wheel-drive capability is curtailed. The control system must constantly balance charging needs against immediate wheel-traction demand, and transitions between modes need to be smooth enough that drivers do not notice them.

Audi has not disclosed whether the patent covers a specific model or when such a system could reach the road. The filing remains at the intellectual-property stage.