(LFT Series) Development of Low Friction Torque Ball Bearing for Differential
JTEKT Corporation has developed a next-generation angular contact ball bearing which is used for the pinion support of automobile differentials which has improved low friction torque performance. With adoption of the oil flow control technology developed for JTEKT’s next-generation ultra-low friction torque tapered roller bearing (hereinafter LFT-IV), this developed product achieves further torque reduction and contributes to the improvement of automobile fuel efficiency.
1. Background of development
Generally, a tapered roller bearing is the mainstream among bearings for the differential pinion of automobile which require the high load capacity and high rigidity. However, tandem angular contact ball bearings (hereinafter tandem AC), to which different ball pitch circle diameters (hereinafter ball P.C.D) are applied to a double-raw ball bearing having the same contact angle direction in order to improve the load capacity and rigidity, have been practically used mainly in Europe since 2005 with the purpose of reducing CO2 emissions and improving fuel efficiency.
We have developed the product which achieves further torque reduction and long life by adopting the technologies for LFT-IV to this tandem AC.
2.Features of this developed product
For this developed product, the oil flow was analyzed utilizing CAE in order to optimize the resin cage and inner/outer ring shape so that the oil flowed into the bearing is limited. We succeeded in reducing a maximum of 30% of agitation loss compared with the conventional tandem AC. With the lowest friction torque among bearings for differential pinion support, this developed product contributes to the improvement of vehicle fuel efficiency by 1%.
Moreover, the amount of contaminant which flows into the bearing is also reduced. Durability is improved by 1.5 times compared with the life of the conventional tandem AC in the contaminated lubricating oil. This technology, which is able to be adopted to the single-row angular contact ball bearing, improves the environmental performance of the differential in which ball bearings are installed and contributes to the improvement of automobile fuel efficiency.
[What is “LFT series”?]
JTEKT has been putting a special focus on “friction” and “lubrication” since our predecessor “Koyo Seiko” time and pursuing low friction torque of bearings. In 1980s, we achieved the reduction of sliding friction on the inner ring rib face and roller large end face of tapered roller bearings and developed world’s first low friction torque tapered roller bearing “LFT” that contributes to the improvement of vehicle fuel efficiency.
After the development, JTEKT continued further research on low friction torque and kept the evolution of tapered roller bearings to “LFT-II”, “LFT-III”, and “LFT-IV”. We have been always leading this field with our No.1 performance and responding to the recent growing environmental awareness.
JTEKT decided to establish the “LFT series” lineup, not only expanding the low friction torque technologies fostered through the development of tapered roller bearing, but also adopting the technologies to the ball bearings, hub units and other bearing-related products.
We will provide low friction torque bearings which contribute to the energy loss reduction for customers in the automotive industry as well as in various industries.
*LFT is the abbreviation for Low Friction Torque, and is a registered trademark of JTEKT Corporation.