Product category:
Bearings
News Release from: NSK UK | Subject: Clutch bearings
Edited by the Engineeringtalk Editorial
Team on 01 December 2000
Magnetic clutch bearings keep cars cool
NSK's new magnetic clutch bearings fulfil the demands of automotive customers for reduced weight, higher performance and easier assembly, with a new ultra-thin compact design.
NSK's new magnetic clutch bearings fulfil the demands of automotive customers for reduced weight, higher performance and easier assembly, with a new ultra-thin compact design that achieves the ideal balance between operating speed, load capacity and operating life The magnetic clutch bearings are a unique design of double row bearing with a one-piece inner ring, a two-point contact, low torque sealing system and special grease
The bearings are used within the clutch of an automotive air conditioner compressor and are located at the drive end of the unit.
As a result, they have to cope with the heavy loads, resulting from the use of poly-vee drive belts, and a severe operating environment of high speeds, high temperatures, vibration and contaminants.
The arrangement of the magnetic clutch bearings within the clutch assembly is that the inner ring is fixed to a spigot and the outer ring fits into a pulley.
The nature of the application means that the outer ring of the bearing has to be capable of high-speed operation.
However, this requirement had to be balanced with another key design demand: bearing life.
The problem the designers faced was a fundamental one: the larger the OD of the bearing outer ring, then the higher the surface speed in the outer raceway, and the shorter the life of the bearing.
The obvious answer was to keep the bearing envelope small.
This, however, solved one problem and created another: namely, designing a small bearing that was rugged enough to cope, yet still able to house the required sealing system.
NSK has managed to reconcile all of these conflicting demands in its final design.
The new double row bearings are compact and ultra thin.
They are manufactured from NSK's unique SUJ2 long-life, ultra clean steel and are designed with a one piece inner ring to ensure greater accuracy, in terms of radial run-out, concentricity and reduced levels of misalignment.
The bearings are also equipped with a one-piece Polyamide cage to enable high-speed operation and reliability in high temperature environments.
In addition, despite the design constraints imposed by the compact bearing envelope, an extremely effective 2-point contact sealing system has been integrated.
This ensures that the special, high temperature and long life grease is retained within the bearing (it must not come into contact with the clutch) and that contaminants such as dust and water are excluded.
Additional benefits of the sealing system also include high speed, low torque and low noise operation.
As well as meeting the key demands for reduced size, high speed and long life, the new ultra-thin bearings ensure optimum clutch plate contact, as a result of achieving minimum levels of angular misalignment in their design.
The double-row configuration is more effective in reducing misalignment than previous arrangements, which featured pairs of single row ball bearings.
The latter pairings invariably suffer from degrees of misalignment unless they are mounted in cross-located or angular contact configurations.
The corollary of this is very careful mounting arrangements by the maker of the housing (pulley) and careful work by the installer.
In contrast, the double-row bearing allows a more stable bearing set-up with the advantage of being a single modular item.
Sealing and installation are also easier, resulting, overall, in a much improved and more cost effective engineering solution. Request a free brochure from NSK UK ...
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