Development of rack-cross type electric power steering
〜 World's first application of electric power steering on large SUV 〜
A rack-cross type electric power steering (RC-EPS) system JTEKT Corporation developed has been adopted by General Motors for use on its Chevrolet Tahoe Hybrid and hybrid GMC Yukon Hybrid, both full-sized SUVs that entered the market in November 2007.
Full-sized SUVs and pickup trucks conventionally have used hydraulic power steering systems, which provide steering force assistance by means of a hydraulic pump driven by the engine. The RC-EPS developed by JTEKT this time boasts world-class output for an EPS system, enabling it to become the world's first EPS system to be installed on a full-sized SUV or pickup truck.
In comparison with hydraulic power steering, EPS, which provides steering force assistance by means of an electric motor, reduces the amount of engine energy loss and improves fuel efficiency from three to five percent. Although this has brought about a rapid shift from hydraulic to electric power steering systems, conventionally the limited output of EPS systems has prevented its application on full-sized vehicles with weight over three tons.
In response to this problem, JTEKT has striven to increase the output of its lineup of EPS systems and has succeeded in developing a rack-coaxial type EPS system for application on the Lexus LS, etc. as well as the RC-EPS for application on full-sized SUVs and pickups. JTEKT will continue efforts to increase the output of EPS systems to enable their application on a greater range of vehicles in order to further contribute to environmental protection.
RC-EPS features
High output, high efficiency
- Development of a special motor for high-output applications
- Achievement of high efficiency by application of a two-stage reduction mechanism using a ball screw and bevel gear
Pleasurable performance
- Development of a resin spiral bevel gear excelling in quietness and heat/wear resistance
Other features
- Improved freedom of vehicle packaging by cross-positioning separating the motor and reduction gear
- Development of an absolute angle sensor in a one-piece structure with the torque sensor
RC-EPS appearance
Relationship between vehicle overall weight and rack output
