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Low-torque Tappet Roller for Automobile Diesel Engines
NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Norio Otsuka) today announced that it has developed a low-torque tappet roller for the rocker arm* of automobile diesel engines.
This new product uses chrome plating on the shaft of the tappet roller to improve the durability for needle roller versions. As a result, it is now possible to replace double roller versions that have a sliding bearing with a needle roller version that has a roller bearing featuring low friction loss. NSK is targeting global sales of 1.5 billion yen in 2019 for this new product, which will help improve the fuel efficiency of automobiles.
* Rocker arm: A mechanism that utilizes the force of the cam to open and close engine valves.
Development Background
In recent years, there has been an increase in environmental awareness, which has led to the need for improved fuel efficiency in automobiles. This need has in turn driven the demand for diesel engines, as they have high thermal efficiency and low CO2 emissions.
However, diesel engines generate soot-NOx (nitrogen oxide) and SOx (sulfur oxide)-during combustion, making for a very harsh environment that increases the likelihood of corrosion wear in the shafts of tappet rollers. As such, tappet rollers used in rocker arms up until now have been designed with a high level of durability.
This time, NSK has developed a new needle roller version (roller bearing) that achieves low friction and high durability. As such, it can be used to replace the conventional double roller version (sliding bearing) used for diesel engines.
Product Features
(1) Low friction
Using the needle roller version (roller bearing) for tappet rollers results in 10% less friction than the conventional bearing.
(2) High durability
Chrome plating has been applied to the tappet roller shaft to suppress corrosion wear, thereby enabling the needle roller version (roller bearing) to achieve high durability in conditions produced by diesel engines.
(3) Possible to apply fixation method using dual swaging (deformation formation) of the tappet roller shaft
NSK utilizes high-adhesion plating on the tappet shaft that makes it possible to use swaging without concern for cracking occurring in the plating. This in turn makes it possible to secure the shaft in place, thereby making it possible to apply the same fixation method as conventional bearings.
Product Benefits
This product contributes to improved fuel efficiency in automobile diesel engines.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 230/530BK NTN | 530 | 780 | 185 |
| 230/530B NTN | 530 | 780 | 185 |