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Products (Transport Instrument - Automobile Parts)

NTN: Hub Bearing with a High-resolution Rotation Sensor & IC Tag Integrated Bearing


History of NTN Corporation
A bearing is a vital mechanical part that enables an axle to rotate. Japanese manufacturers occupy a significant share of the global bearings market, at about one third, with NTN one of three companies making up the majority of this overall Japanese share.

NTN was founded in 1918, specializing in the manufacturing and sale of bearings, going on to gradually establish an international market presence. It has also been strongly focused on basic research in the field. NTN’s findings have contributed to the development of better solutions to combat friction from bearings, and improvements in lubrication and material surfacing. It has also conducted basic research in the development of new materials, such as functional resins and ceramics, as well as measurement technologies. 

Findings from this research led, from the 1980s onwards, to the company launching the manufacturing and sale of constant velocity joints for automobiles, in addition to bearings. Since then, NTN has continued to expand the range of products that make up its core market performers, including axle units. It has successfully transformed itself from a specialist bearings manufacturer into a company producing a diverse range of precision machinery and machine components. Today, in addition to precision instruments, NTN is enterprisingly diversifying its business to cover a wide range of other sectors.

Herein its two latest products, among those representing the broadly diversified business, are showcased.

Hub bearing with a wide-range high-resolution small sensor
In 2009, NTN announced a hub bearing with a wide-range high-resolution small sensor, which is equipped with a high-resolution rotation sensor jointly developed with the French company NTN-SNR (former SNR) (Fig. 1).
This hub bearing enables the sophisticated control of vehicles.
Fig 1
Figure 1. Hub bearing equipped with a wide-range high-resolution small sensor.

In general, axle rotation sensors such as antilock brake systems (ABS) and electric stability controls (ESC) that detect vehicle speed and allow greater control are integrated into the vehicle’s axles. An axle rotation sensor has the capability to detect magnetic pole changes in an encoder (rotating side), which is alternately magnetized by NS magnetic poles with an equal interval in a circumferential direction, with a sensor (fixed side). It is utilized in the control of vehicles as a device to provide information on axle rotation.

NTN integrated this axle rotation sensor into a wheel bearing (hub bearing), which can provide two types of signals, conventional ABS signals and high-resolution signals, thus developing a hub bearing with a compact wide-range high-resolution sensor. At low and medium velocities, wheel rotation speeds can be detected at a resolution up to 40 times better than conventional techniques by utilizing this high-resolution signal. Thus slight changes in a vehicle’s motion can be detected and it is possible to control the braking force with optimum timing. On the other hand, at high speeds, data processing loads can be reduced using conventional ABS signals. A tiny backward-and-forward motion of a vehicle can be detected with this axle rotation sensor, which is expected to be utilized for a wide variety of vehicle control applications such as backward motion detection on a hill start and sensing during automated parking. Additionally, the continuing reduction in integrated circuit (IC) size has resulted in improved freedom of design and reduced whole sensor size.

NTN is conducting marketing activities around the world for this newly developed product, which would contribute to increased sophistication of vehicle control.

IC tag integrated bearing
NTN’s manufacturing technologies of established bearing products have a global reputation. Such product lines are markedly superior in wear resistance; repair and replacement are normally due to long term use of the bearings. Bearings are important components of many systems and more detailed information management is required.

NTN has developed an ‘IC tag integrated bearing,’ in which the detailed quality information and usage history of the bearing can be stored and read out as necessary (Fig. 2).

Fig 2
Figure 2. IC tag integrated bearing

So far, ideas to integrate IC tags into bearings to aid required daily maintenance routines have indeed been proposed. However, they have not been realized because data cannot be read out in principle from IC tags that are embedded in metals, or if the size of the IC tag itself is too large to be practically incorporated.

To overcome these difficulties, NTN has manufactured IC tag integrated bearings by developing a small IC tag (4.5 mm in diameter) that does not affect overall bearing size and can store electronic information even when embedded in bearings. Data on these IC tag integrated bearings can be read out and stored using a dedicated reader–writer. Example data fields that can be stored include inner and outer diameters and accuracy of breadth before shipment, as well as date of manufacture and inspection date. What’s more users can freely specify stored data.  

Future of NTN
NTN is working hard to diversify their business; it is aggressively undertaking development not only in precision machine components like bearings but also in areas that are expected to have a growing demand in society in the future, such as natural energy and in-wheel motors.

Since a sales office was established in Germany in 1961, NTN has been actively pursuing globalization and is currently based in the Americas, Europe, Asia, and Oceania, covering the growing worldwide market. NTN will not only continue to diversify and globalize, but also make the transition in several years from a precision machinery component manufacturer to a conglomerate enterprise with annual sales of over 10 billion US dollars, while placing utmost importance on field technologies.

Sep 21, 2011

About the author
Eriko Kinashi is a reporter for Japanest NIPPON
(NTN Corporation)