Honda has revealed details of a new single-motor hybrid system that it plans to use for future small, efficient cars.
The system is to form part of the company’s petrol-electric hybrid drivetrain range, which will also include a two-motor system for larger cars and a high-performance three-motor arrangement.
Using a seven-speed dual-clutch gearbox with a 1.5-litre four-cylinder Atkinson Cycle engine, the next-generation drivetrain is claimed to raise efficiency by 30% over a conventional one-motor hybrid alternative.
Modern Atkinson Cycle engines use unusual valve timing to produce less heat and other effects linked to efficiency. Outright power is sacrificed in the process, but Honda’s system aims to use the electric element of the drivetrain to ensure driving enjoyment.
An active dual-clutch transmission engages and disengages the engine to allow electric-only running at low-to-medium speeds, while engaging both for faster acceleration and high-speed cruising. During deceleration the clutches decouple the engine for better energy recuperation.
The system joins a two-motor hybrid system that Honda claims is the world’s most efficient. Paired with a 2.0-litre Atkinson Cycle engine it has three drive cycles where it uses either the motors only, the engine only or a combination of both.
Acting as a halo drivetrain is the three-motor setup that has been confirmed for the forthcoming Honda NSX. It places a motor at each of the rear wheels, where torque can be managed directly and entirely independently to enhance handling. It is expected to function like a more complex version of the ‘torque vectoring’ seen on performance cars from manufacturers like Porsche.