Mazda patents hybrid powertrain with rotating, 3 electric motors

For many purists, Mazda will forever be linked to the rotary engine that the company first launched in the 1967 Cosmo Sport and later in a range of RX-badged sports cars.

Over the years, rotary engines have played an important role in the company’s history, including powering a Le Mans winner, and the engine made a comeback earlier this year, as a range extender for the MX30 compact electric crossover, although not in the US market.

But might we see a more powerful rotary in a modern RX? The biggest hurdle remains making sure the fuel-thirsty engine meets strict emissions regulations while increasing power. Mazda’s last rotary sports car, the RX-8, had only 232 horsepower but a V-8-like thirst.

Patent activity suggests Mazda is looking at hybrid technology as a possible solution for a turntable car that directly drives the wheels.

As first noted by The Drive, a patent filed by Mazda was published this week at the United States Patent and Trademark Office describing a hybrid system that combines a front-mounted rotary engine (12) with one of the two power units send drive to a transaxle (14c) and finally to the rear wheels (2a). Two more electric motors (20), described as in-wheel hub motors, complete the powertrain, turning it into an all-wheel drive setup.

A similar patent surfaced last year, but the latest gives much more detail on the electric side of the powertrain. The two motors in the wheel are described as 17 kW (23 hp) induction motors, while the motor combined with the rotary is described as a 25 kW (36 hp) permanent magnet synchronous motor.

The latest patent also has an interesting concept for the battery system (18) to store recovered energy and power the electric motors. The system is a unique variable voltage system where four individual 48-volt battery systems are packaged for ideal weight distribution. The systems operate individually during normal driving, but when peak power is required, switches can connect the batteries to form 96-volt units. Such a design means fewer high voltage connections are required, helping to reduce weight.

Mazda has made no mention of plans to launch a modern rotary sports car, although there have been plenty of hints over the years, culminating in the unveiling of the RX-Vision concept in 2015. All patent activity suggests that Mazda i haven’t given up on the idea of ​​a rotating sports car, even in a world of increasingly stringent emissions standards.