September 18, 2007
First new product developed by blending high technologies of SNR and NTN
Development of “Hub Bearings with High resolution rotational sensors”
[ Contributing to better vehicle safety control ]
NTN Corporation (hereafter NTN) jointly with SNR (France) has developed Hub bearings with high resolution rotational sensors that contribute to vehicle safety control.
A wheel rotational sensor enabling precise control of ABS*1 and ESC*2 is integrated in a wheel bearing (Hub bearing). This sensor is composed of a magnetic sensor to detect the change of N/S polar characters and a magnetic encoder where N/S poles are magnetized alternatively in the same distance in a circumferential direction. The magnetic sensor detects magnetic encoder changes alternatively as the wheel rotates, and they are used for vehicle control. If the rotation detection signals are upgraded to higher resolution due to a smaller magnetization pattern, more precise vehicle control is achieved. However, it has been an issue that the smaller the magnetic pole, the weaker the generated magnetic force becomes and it’s hard to obtain a rotational signal.
“Hub bearings with high resolution rotational sensor” was made a reality by blending SNR’s magnetic sensor technology where it’s magnetic encoder achieved resolution 40 times that of conventional types. NTN’s 3rd generation hub bearing technology includes seal designs to protect sensor electronic parts from the external environment. The signal processing method was also improved to upgrade not only high resolution but also accuracy.
Optimum brake force adjustment timing becomes possible because the wheel rotational speed is detected in a shorter time interval by this new product. Also, the rotational speed of left and right wheels can be measured more precisely and the amount of tire skidding caused by wheel speed differences during cornering is more quickly predictable.
NTN will approach customers, proposing this new product that contributes to upgrading vehicle safety control. This is the first product jointly developed by NTN and SNR, and we will continue to pursue the synergistic effects of both companies in R & D.
| *1 ABS: | Antilock brake system (Antiskid brake system) |
| *2 ESC: | Electronic stability control (Vehicle stabilization system) |
[ Features ]
| a. | High resolution rotational signal (×40 relative to conventional types, Magnetic encoder is the same as conventional types) | |
| b. | Possible to distinguish the rotational direction by B phase pulse output | |
| c. | External dimensions are the same as conventional hub bearings, Applicable to both driven and non-driven wheels | |
[ Product Photo ]
[ Reference ]World top market share in Hub bearing business
| A Hub bearing is a power train component for vehicle applications. It is also called an axle bearing. It is fitted in a hub that connects vehicle body and wheels. Hub bearings are composed of inner rings, outer rings and steel balls or rollers. During modularization, evolution of the bearing from the 1st generation to the unitized 3rd generation is progressing by means of reduction of number of components, reduction in weight and compact designs. Hub bearings are one of NTN’s “Strategic products” and NTN is making every possible effort through development, production and sales, to concentrate resources on this product. Last year, NTN and SNR came to an agreement that will give NTN controlling interest in SNR. This agreement will yield a hub bearing world market share of 22%. NTN’s goal is to increase its world market share to 26% by March 2010. (Market share value is NTN’s estimation) |
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Sensor technology of SNR
SNR Roulements (hereafter SNR) is one of the world’s leading bearing manufacturers with it’s Head Office is in Annecy, France. SNR began bearing production in 1880. It was acquired by French auto maker, Renault in 1964 and became a 100% owned subsidiary. In March 2007, NTN and SNR reached an agreement on business and capital tie-up. In March 2008, NTN will acquire the majority of its capital and SNR will be a consolidated subsidiary of NTN.
SNR is a world leader in anti-lock brake sensor technology. This is the first NTN and SNR joint development since both companies entered into a business agreement.