2011
Development and Commercialization of Various New Systems for Drive and Steering Systems of Next-Generation EVMarch 25, 2011
NTN Corporation (hereafter, NTN) has developed and commercialized an “In-wheel motor system” where a motor and speed reduction mechanism are directly mounted to the wheel, and a one motor type “One motor type EV drive system” for the drive system, and a “Steering system for steer-by-wire” for the steering system, for use in next-generation electric vehicles (hereafter, EV).
The outline of each of the developed systems is as follows. Please refer to the New Product and Technology Info for details.
(1) In-wheel Motor System
NTN developed an “In-wheel motor system” in which a control system (including an inverter) coupled to the sensor information, is incorporated in the in-wheel motor.
The in-wheel motor system does not require an engine, transmission, gears, drive axles and etc. compared to internal combustion engine vehicles, which improves the mileage per charge (electric costs) due to the reduced weight, and greatly increases the flexibility of the space and body design. Drive shafts are also unnecessary, which enables parallel movement and turning on the spot. Furthermore, it is possible to adjust the driving force of each right and left wheel with a control system, which improves the traveling safety.
NTN has already performed various durability tests, such as submersion tests and vibration tests repeatedly, and ensured sufficient reliability during actual running, and even when this system is applied to only two wheels of a passenger vehicle, a driving performance equivalent to a compact vehicle can be achieved.
(2) In-wheel Motor System for Electric Commuters
NTN developed an “In-wheel motor system for electric commuters”, while promoting the development and commercialization of the in-wheel motor system.
As for future expansion, this system is expected to be used in an EV for use in short driving distances for shopping and commuting, an EV friendly to senior citizens which is easy to get in and out of, two-seater electric commuters suitable for practical use in EV towns and one-seater electric minicars.
A compact and lightweight in-wheel motor system was realized, which can be applied to electric commuters by changing the mechanism of the hub bearing, reduction gear and motor which are the component parts.
(3) One Motor Type EV Drive System
NTN developed the world's first “One motor type EV drive system” with an automatic transmission which consists of a compact and lightweight drive motor, differential and inverter, using a new two-speed automatic transmission which is an alternative to the conventional fixed type transmission for the one motor type, which is currently the mainstream for EV.
The motor can be used at a high efficiency by using the uniquely compact two-speed automatic transmission for the transmission mechanism, which improves the system efficiency and increases the cruising range per charge. In addition, weight reduction of the system was achieved in contrast to the conventional fixed transmission type EV drive system, by utilizing a high-speed compact motor.
NTN will offer this system as the “NTN one motor type EV power train” by adding a constant-velocity joint, Multi Axis Load Sensor Integrated Hub Bearing and etc., which are the main products of NTN.
(4) Steering System for Steer-by-Wire
NTN developed a “Steering system for steer-by-wire” which transmits the steering wheel operation by an electrical signal, as a next-generation vehicle steering system.
This system converts the steering amount of the steering wheel to an electric signal, and drives the wheel-turning actuator depending on the amount to change the direction of the tires. NTN developed the world's first system which ensures safety, by instantly switching the sub-motor to a wheel-turning function when a failure occurs, such as a burnout of the main motor as the system is equipped with a sub-motor for the right and left independent wheel-turning operation, in addition to the main motor for the wheel-turning operation.
In the future, NTN will offer these system products, and continue to respond to the various EV development needs by proposing and offering complex system products combined with “Electric brake actuators”, “Multi axis load sensors”, “High-resolution rotary sensors”, “High precision magnetic type high resolution angle sensors” and etc.