KYMCO manufactures in-wheel motor for its electric motorbike

Tinuku - Kwang Yang Motor Co (KYMCO) developed a compact electric motorbike that has an in-wheel motor (IWM) for driving the motorbike in its rear wheel. The largest manufacturer of two-wheeled vehicles in Taiwan, developed the IWM and manufactures it in house.

It realized the cost-competitive, low-priced IWM and manufactures it in its factory in Kaohsiung, Taiwan, together with the motorbike. The company plans to release the vehicle equipped with the IWM in Taiwan in October 2018 and in other regions including China and India in three years.

Tinuku KYMCO manufactures in-wheel motor for its electric motorbike

The vehicle to be released by KYMCO is a scooter-type motorbike and will be sold under the name of "Nice 100 EV." It measures 1,710 (L) x 650 (W) x 1,010mm (H). Its wheelbase and mass are 1,200mm and 87kg, respectively. Its maximum speed is 45km/h (approx 28mph).

The maximum output and maximum torque of the IWM are 1.5kW and 50N·m, respectively. Small-output motors are suited for use in wheels. They reduce speed by using planetary gears embedded inside, making it possible to eliminate the need for reduction gears, which are normally combined.

The number of their parts can be easily reduced, and, therefore, their size and weight can be reduced. As a result, they can be easily contained in rear wheels, KYMCO said.

"IWMs can be manufactured at lower costs than normal driving motors, enabling to reduce the costs of vehicles," KYMCO said.

On the other hand, when the output of a motor increases, so do the size of the motor and the weight of the wheel. As a result, it becomes necessary to thicken the swing arm and body frame, which support the wheel, weakening the advantage of in-wheel motors.

"With existing technologies, the maximum output of an IWM can be increased up to 2kW," the company said.

For electric motorbikes that need an output higher than 2kW, normal external motors are used. For example, "Many 110 EV," which KYMCO decided to release two month earlier than the Nice 100 EV, does not use an IWM.

The distance between its rear axle and the drive axle of its motor is about 10-15cm, and they are connected by using a few reduction gears between them. Its maximum output is 3.2kW, which is more than 100% higher than that of the IWM of the Nice 100 EV. On the other hand, its maximum torque is as low as 16.5N·m.

It is rare that a major motorbike maker manufactures an IWM in house. Even China-based motorbike makers that have mass-produced compact electric motorbikes procure motors from, for example, Robert Bosch GmbH, relying on other companies' technologies in many cases. KYMCO manufactures in-wheel motor for its electric motorbike

On the other hand, KYMCO sticks to the in-house production of motors, considering that they directly influence the traveling performance of electric motorbikes and considering them as a key component that determines the value of the vehicle.

Even Honda Motor Co Ltd and Yamaha Motor Co Ltd, which have large shares of the global market for motorbikes, have not yet mass-produced electric motorbikes equipped with an IWM. In regard to electric motorbikes, Japanese manufactures are lagging behind foreign manufacturers.

Both the Many 110 EV and Nice 100 EV come with a "replaceable" lithium-ion rechargeable battery pack. As in the case of the motor, KYMCO manufactures the battery pack in house but procures battery cells from Panasonic Corp, the LG group and Samsung Electronics Co Ltd.

The capacity of the battery pack is 0.65kWh, and two units of the pack are inserted into the footrest. In addition, the Many 110 EV and Nice 100 EV are equipped with a 0.4-0.5kWh battery pack called "Core Battery" in the seat.

With the three battery packs, they can travel about 100km. Also, three more batteries can be stored in the space for a helmet, enabling to travel up to 200km without charging a battery. Basically, electricity is supplied to the Core Battery and replaceable battery packs by using a home-use charger.

If the remaining battery level becomes low at the time of traveling, the battery packs can be replaced with fully charged packs at a charging station. While it takes about four hours to fully charge the battery pack with the home-use charger, it can be shortened to less than 10 seconds by replacing battery packs.

The charging platform of KYMCO is called "iOnex," which the company will deploy in 20 countries in the next three years. KYMCO pans to release 10 kinds of electric motorbikes during the period.

However, few of them have an output equivalent to or lower than that of the Nice 100 EV, and, probably, few of them will come with an IWM. KYMCO is making efforts to increase the number of components shared among motors in the aim of reducing costs of the entire product line.