October 5, 2006
NTN Develops an Environmental Friendly Low Friction Needle Roller Bearing For Automotive Engines
Improves Automotive Fuel Efficiency by 3% and Makes Oil Pumps
and Starters More Compact and Light Weight
NTN Corporation (NTN) has developed Low Friction Needle Roller Bearings for automotive crankshaft and camshaft support applications. These bearings reduce torque considerably when compared to conventional plain bearings.
In recent years, engine oil viscosity has become lower to help reduce friction and improve fuel efficiency. In light of this, the use of rolling bearings instead of plain bearings has been considered to help reduce friction in the engine shaft support applications.
However, it is impossible to mount normal rolling bearings in these applications. Because of the crank arm and cam on the crankshaft and camshaft, only split type bearings with small cross-sectional heights will work. There have been no rolling bearings available to meet these needs. For this application, until now, either split type plain bearings have been used or the aluminum housing and shaft were placed directly in sliding contact.
In response to this, NTN has developed a split type rolling bearing for these two applications. NTN's newly developed Low Friction Needle Roller Bearings have a small cross-sectional height and can be easily mounted on the crankshaft and camshaft, contributing to increased automotive fuel economy and a more compact design.
For crank-shaft support applications:
Both the outer ring and the cage are split into two pieces. NTN's new split technology has made possible a high precision outer ring with a small cross-sectional height of 2mm. NTN's engine bearing technology also improves the cage's anti-seizure property and strength.
For cam-shaft support applications:
The drawn-cup outer ring is split into two pieces and the plastic cage is one piece but cut at one place. The use of a split drawn-cup made it possible to decrease the outer ring cross-sectional height to 0.6mm, which contributes to space reduction. Also, the outer ring strength was increased by optimizing its configuration using FEM analysis.
[Features: (compared with plain bearings)]
| (1) | Startup torque reduced by approximately 90% |
| (2) | Rotational torque reduced by approximately 50% |
| (3) | Increased vehicle fuel efficiency by approximately 3% (measured by "10.15" gas emission test run mode) |
| (4) | Making engine oil-pump and starter more compact and light weight (VA/VE can be expected) |
[Photos]
[Advantages]
[How it Works]
| (1) | For crank-shaft support applications: | |
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Outer ring sectional height decreased to 2mm by NTN's new production method to split outer ring ⇒ Contributing to space reduction Cage anti-seizure property and strength improved by NTN's engine bearing technology |
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| (2) | For cam-shaft support applications: | |
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Outer ring sectional height decreased to 0.6mm by using press formed drawn-cup outer ring ⇒ Contributing to space reduction Outer ring strength improved by optimum design using FEM analysis | ||
[Performance:
(Measured torque value, in comparison with plain bearing)]
| · | Startup torque | : 90% less |
| · | Rotating torque | : 50% less |