In one aspect of the invention, a retainer assembly for a power steering assist system is provided. The retainer assembly includes a retainer having an inner wall defining an opening, at least one permanent magnet coupled to the retainer, and at least one spiral channel formed in the inner wall.

The invention relates to a power steering assembly for a hydraulic power steering system of motor vehicles, comprising at least one hydraulic servo valve with a control member (3) for controlling the steering assistance in accordance with a relative rotation of an input shaft with respect to an output shaft (2), and at least one actuator (9) for the relative adjustment of the control member (3) with respect to the input shaft or output shaft (2) in order to influence the steering assistance characteristic. Further, the power steering assembly comprises a summation gearing having a first rotatable drive member (4) that is in operative engagement with the control member (3), and a second rotatable drive member (5) that is in operative engagement with an output element (8) of the actuator (9), and an output member (6). The summation gearing superposes a rotation of the first drive member (4) with a rotation of the second drive member (5) and drives, via the output member (6), an epicyclic gearing with at least one planetary gear (11), which is in operative engagement together with both the input shaft or output shaft (2) and with the control member (3) and can be rotated both about a planetary axis (14) fixed with respect to the frame and about its own axis of rotation (12) orbiting about the planetary axis (14), in such a way that a rotation of the first drive member (4) causes a rotation of the own axis of rotation (12) of the planetary gear (11) orbiting about the planetary axis (14) in such a way that no rotation of the planetary gear (11) about its own axis of rotation (12) occurs as a consequence, but a rotation of the second drive member (5) causes a rotation of the planetary gear (11) about its own axis of rotation (12), wherein the rotation of the planetary gear (11) about its own axis of rotation (12) causes a relative rotation of the input shaft or output shaft (2) with respect to the control member (3).

A control system and method for a hydraulic-power steering system of a vehicle including magnetic torque overlay (MTO) is provided. The control system and method minimize undesirable vibration in a handwheel of the vehicle as a result of disturbance in its front road wheels (e.g., road-wheel imbalance). In the control system and method, a base torque command is determined or generated. At least the base torque command is passed to a disturbance-rejection module. The disturbance-rejection module modifies the base torque command to minimize the vibration.

Technical solutions for compensating for lash in a steering system are described. An example method includes determining a rack pressure value based on a driver torque value and a differential pressure across a rack of the steering system. The method also includes determining a compensation friction value based on a position of a handwheel of the steering system and a speed of a vehicle equipped with the steering system. The method also includes computing a pressure value based on the rack pressure value and the compensation friction value. The method also includes generating a torque command using the pressure value, the torque command being added to the driver assist torque for the steering system.

A power steering assembly for a hydraulic power steering system of motor vehicles includes an input shaft configured for connection to a steering wheel, an output shaft coupled to the input shaft configured for operational engagement with a steering rod, a hydraulic servo valve, an actuator, a sensor system, and an evaluation unit. The coupling between the input and output shafts is realized by a torsion bar and permits a first relative rotation between the input and output shafts. The hydraulic servo valve, which controls a hydraulic pressure and thus a steering assistance depending on the steering torque applied by a driver, has a rotatable control element engaged with, and driven by, the output shaft. An engagement between the output shaft and control element provides for a second relative rotation therebetween. This engagement includes a multi-stage planetary gear unit. The steering power assistance system is controlled depending on a third relative roation between the input shaft and control element. The actuator relatively displaces the control element in relation to the output shaft to influence the steering power assistance characteristics. The sensor system measures at least one differential angle between the control element and input shaft, wherein the control element is a valve sleeve disposed coaxially with the input and output shafts and the sensor system includes an encoder sleeve non-rotatably connected to the valve sleeve.

A power steering assist system includes a hydraulic assist power steering assembly configured to couple to a vehicle steering gear, and a hydraulic pump having an electric motor, the hydraulic pump configured to supply pressurized hydraulic fluid to the hydraulic assist power steering assembly.