Development of dual-pinion type electric power steering (DP-EPS)
～High output and markedly improved engine room packaging～

JTEKT Corporation has developed a dual-pinion type electric power steering (DP-EPS) system that features both high output and improved engine room packaging.

There generally are three types of electric power steering (EPS), depending on the positioning of the motor/reducer unit: column type (C-EPS), pinion type (P-EPS), and rack type (R-EPS). The best type for any given vehicle model depends on that model’s particular characteristics.
　 In the case of P-EPS, the assist mechanism (motor/reducer unit) is positioned in the engine room and provides assist force to the shaft extending from the steering wheel. P-EPS excels in quietness and is used mainly on mini-vehicles and small-class cars.
　 This new DP-EPS was developed in response to demands for P-EPS with higher output and improved engine room packaging. Regarding the structure, JTEKT separated the assist mechanism from the steering wheel shaft and adopted a structure featuring two pinions meshing with the rack bar at separate locations to allow greater freedom in assist mechanism design. JTEKT also utilized its wealth of experience to develop new technology such as a compact, high-strength reducer for this product. As a result, the developed DP-EPS features better engine room packaging and higher output than conventional P-EPS. The greater output in particular makes it applicable on medium-sized vehicles. By development of this DP-EPS, JTEKT has succeeded in expanding its lineup of EPS products.
　JTEKT will begin mass-producing DP-EPS in Europe in the latter half of 2011 and aims to expand sales to automakers in Japan and overseas.

Features of developed product

1. Output: 20% higher than that of conventional (JTEKT) P-EPS

2. Improved engine room packaging

・Separation of assist mechanism and steering wheel shaft, improved vehicle layout centrality

・Structure allowing free assist mechanism positioning around and along the rack bar

Appearance

Structure