Yamaha Motor Co Ltd unveiled a concept model of a four-wheeled series hybrid vehicle (HEV) at Tokyo Motor Show 2017, which was open to the public from Oct 28 to Nov 5, 2017 (Yamaha to Exhibit 4-wheeled Compact Series HEV).
The HEV, "MWC-4," can be driven with an ordinary motor vehicle license in Japan. The company defines the vehicle as an "ultra-small mobility."
The most distinguishing feature of the MWC-4 is that it is equipped with a "leaning multi-wheel (LMW) mechanism" and runs on four wheels. Compared with Yamaha Motor's two-wheeled vehicles and "Tricity MW125" three-wheeled vehicle, the running stability of the MWC-4 can be more easily improved (See related article).
"The basic technologies (of the MWC-4) are based on those of our three-wheeled vehicles such as the Tricity, but we renovated the shape of the mechanism," Yamaha Motor said.
The previous mechanism consists of "parallelogram links" and "cantilever telescopic suspensions." There are two links arranged in parallel with each other. The center of each link is fixed to an auto body so that they form a rectangular shape when the vehicle is turning.
With this mechanism, the parallelogram links move the right and left suspensions to different positions when the vehicle is turning. The right and left wheels move in different directions (up and down) while being in parallel with each other. The vehicle leans its right and left wheels in a direction in which the driver moves the steering wheel.
This time, Yamaha Motor employed a double wishbone for both the front and rear wheels of the four-wheeled concept, in place of the rectangular link. The stability of the MWC-4 is high even when it is running at a high speed. The new system is being increasingly employed for four-wheeled sports cars.
The company made some original improvements to the concept car. For example, a shock absorber that absorbs impacts from the road surface is fixed while being separated from the vehicle frame.