Electromagnetic control apparatus for varying the driver steering effort of a hydraulic power steering apparatus.

摘要

A hydraulic power steering apparatus having conventional relatively rotatable valve spool (54) and valve body (64) for flow regulation, and an integral electromagnetic mechanism (92) which effectively varies the centring force between the valve spool and valve body to adjust the level of steering assist provided for a given operator steering input. The electromagnetic mechanism comprises a rotary multipole permanent magnet (100) supported for rotation with one of the valve spool and valve body, a rotary flux conducting element (142,144) supported for rotation with the other of the valve spool and valve body, and a stationary exciting coil (134) magnetically coupled thereto. The exciting coil is energized so as to produce a variable centring force between the valve spool and valve body with vehicle speed, which produces a corresponding variation in the driver steering effort.