Contributing to improved fuel efficiency through reduced friction loss
NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Toshihiro Uchiyama) today announced that it has developed the world’s smallest roller thrust needle bearing for planetary gear mechanisms* for use in automobile multistage automatic transmissions (step AT).
Washers (slide bearings) are used in planetary gear mechanisms for step AT; however, their friction loss reduction became an issue. To solve this, NSK developed the world’s smallest roller at a diameter of Φ1 mm x length 1.8 mm, making it possible to replace the washers with thrust needle bearings. This solution significantly reduces friction loss.
NSK is targeting 1.8 billion yen in global annual sales in 2020, enhancing the efficiency of step AT’s and thus increasing automobile fuel efficiency.
* Planetary mechanism: A reduction mechanism adjusts output speed and torque by utilizing a combination of rotation and revolution movements of multiple gears.
In recent years, the demand for improved automobile fuel efficiency has grown on a global scale, resulting in the development of more efficient transmissions. The step AT multistage design improves transmission efficiency, which has resulted in the significant growth of this technology.
The number of planetary mechanism increases along with the multistage design of step AT. Therefore the number of washers (slide bearings), which comprise the planetary mechanism, increase. This results in the generation of friction loss, which then becomes an issue.
NSK developed a thrust needle bearing that is the same size as the washer (slide bearing), and it can thereby replace it. This product reduces friction loss and improves durability in high-speed revolution environments.
(1) Reduced friction loss
Friction loss is reduced by 70 to 80% compared with washers.
(2) Changes to dimension of peripheral parts are kept to an absolute minimum
By combining the world’s smallest roller at a diameter of Φ1 mm (length, 1.8 mm) and a 0.2 mm thick race, the component is the same size as the washer, making it replaceable.
(3) Improved durability in high-speed revolution environments
By placing lubrication holes on the inner side of the plastic retainer, lubrication is maintained in high-speed revolution environments.
This design results in improved anti-seizure performance.
This product contributes to higher step AT efficiency and improved automobile fuel efficiency.