Electric power steering system

Abstract

An electric power steering system in which assembling workability can be enhanced by reducing to a minimum required ground processing of each portion requiring grounding. The electric power steering system comprises a steering column (3) incorporating a steering shaft (2) to which steering torque is transmitted, and an electric motor (5) for transmitting a steering auxiliary power to the steering shaft (2) through the reduction mechanism in a reduction gear box (4), wherein a control unit (19) including substrates (23, 25) mounting a control circuit performing drive control on the electric motor is attached to the reduction gear box (4), the joint of the electric motor (5) is electrically connected with the control unit (19) directly, and connection of the reduction gear box (4) and the control unit (19) to the ground is made through a ground connection wire (29) arranged between the control unit (19) and a power supply section (30).

Description

technical field [0001] The present invention relates to an electric power steering apparatus having: a steering column housing a steering shaft to which steering torque is transmitted; and an electric motor which transmits steering power to the steering column through a reduction mechanism in a reduction gear box . Background technique [0002] As a conventional electric power steering device, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2005-329866), Patent Document 2 (Japanese Patent Laid-Open No. 2005-329867), Patent Document 3 (Japanese Patent Laid-Open No. 2005-329868 Publication) and Patent Document 4 (Japanese Patent Laid-Open No. 2005-329869), an electric power steering device is proposed in which a rack shaft or a steering gear A part of the housing that houses the motor and houses the control board that drives and controls the motor is formed on the rack case or the steering gear box. When the mounting boss (boss) at the bottom abuts, the board c...

AI Technical Summary

Problems solved by technology

[0005] In this way, in the column-type electric power steering device, since both the steering column case and the control circuit need to be grounded, the assembly workability of the electric power steering device is reduced, and since the grounding of the two paths The wires are wired to different parts of the vehicle, and there will be relative potential differences, and there will be unsolved problems such as a decrease in electromagnetic environment compatibility (EMC) or fluctuations in control accuracy due to ground potential differences.

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