Honda's New HEV Separately Controls Rear Wheels With 2 Motors

Dec 7, 2011
Naoshige Shimizu, Nikkei Electronics
The HEV has an engine, a DCT and a motor in the front part and two motors in the rear part.
The HEV has an engine, a DCT and a motor in the front part and two motors in the rear part.
[Click to enlarge image]
An example of drive force allocation
An example of drive force allocation
[Click to enlarge image]

Honda Motor Co Ltd prototyped a hybrid electric vehicle (HEV) that has an engine and a motor in the front part and two motors in the rear part.

The company aims to realize a performance equivalent to that of a V-eight engine and a fuel efficiency equivalent to that of an in-line four-cylinder engine at the same time. The HEV was prototyped based on the North American model of the "Accord."

The release date of the HEV has not been decided yet. The vehicle was announced at 2011 Honda Meeting, which took place Dec 5, 2011.

The HEV's hybrid system, which is transversely mounted in the front part of the vehicle, connects the engine and the motors via a seven-speed DCT (dual clutch transmission) being developed by Honda. On the rear side, two motors having the same output power are placed at the center of the axle and connected to the right and left tires, respectively.

When the HEV starts moving or runs at a low speed, it is driven by the rear motors. When a large drive force is required, the front motor is used in addition to the two rear motors. And when a larger force is required, the engine is used as well.

As for the motor control, Honda realized the function of the "SH-AWD," which was developed by the company in 2004 and changes the drive force allocation for the two rear wheels in accordance with running conditions, by using the two rear motors. Therefore, the company calls the new hybrid system "Electric-powered SH-AWD."

For example, when the HEV is turning to the right, the drive forces of (1) the motor for the right rear wheel, (2) the motor for the left rear wheel and (3) the motor for the front wheels are directed backward, forward and forward, respectively, so that the yaw moment of the vehicle is controlled and it becomes easy to turn to the right.

Furthermore, it is possible to charge the battery with the electricity regenerated by directing the drive force of the motor for the right rear wheel backward. In the case of the existing SH-AWD, the force of the engine is transmitted to the rear side by using a propeller shaft, and the drive force allocation for the two rear wheels is changed with an allocation device.

The HEV is equipped with a 3.5L direct-fuel-injection V-six gasoline engine. The output power of the front motor is 30kW or higher, and each of the two rear motors has an output power of 20kW or higher. There is a clutch between the two motors. The cells used for its lithium-ion rechargeable battery are made by Blue Energy Co Ltd, and their capacity has not been disclosed yet.