Honda Announces Japan's Most Efficient HEV

Jul 20, 2013
Yutaka Chikaoka, Nikkei Monozukuri
The new model of the "Fit Hybrid"
The new model of the "Fit Hybrid"
[Click to enlarge image]
The "Sport Hybrid Intelligent Dual Clutch Drive" single-motor hybrid system
The "Sport Hybrid Intelligent Dual Clutch Drive" single-motor hybrid system
[Click to enlarge image]

Honda Motor Co Ltd announced July 19, 2013, that it has developed a new model of the "Fit Hybrid" as a hybrid electric vehicle (HEV) based on a compact car and realized the highest fuel efficiency in Japan.

The fuel efficiency of the new HEV is 36.4km/L (approx 85.6mpg) under the JC08 test mode, which is 10.0km/L and 1.0km/L higher than the fuel efficiencies of the previous model of the Fit Hybrid (26.4km/L) and Toyota Motor Corp's "Prius c" HEV (35.4km/L), respectively. Honda plans to release the new HEV in September 2013.

The new Fit Hybrid is the first vehicle that comes with the "Sport Hybrid Intelligent Dual Clutch Drive," a single-motor hybrid system that Honda developed for compact cars. For the combustion cycle of the gasoline engine, Honda employed the Atkinson cycle, which has a high expansion ratio and high thermal efficiency.

For the in-line four-cylinder engine, whose displacement is 1.5L, Honda used a seven-speed dual-clutch transmission (DCT) equipped with a high-output motor and an intelligent power unit (IPU) equipped with a lithium-ion (Li-ion) rechargeable battery. The IPU controls the motor and supplies electricity.

To the hybrid system, Honda added an electric servo brake, which improves electric power regeneration efficiency, and a fully-electric compressor, which reduces engine load. As a result, the company improved fuel efficiency by 35% or higher, compared with the "IMA," its previous single-motor hybrid system.

The Sport Hybrid Intelligent Dual Clutch Drive hybrid system switches power sources depending on driving situations. Specifically, when the vehicle is accelerating or running at a high speed, it engages the clutch to drive both the engine and motor.

When the vehicle is starting up or running at a low or medium speed, it disengages the engine by using the clutch and runs only on the motor. When the vehicle is decelerating, it disengages the engine by using the clutch to increase the amount of regenerated energy. As a result, both fuel efficiency and driving performance were improved.

Honda has not yet decided the price of the new HEV.