A turning system is configured to move a turning shaft to turn a left wheel and a right wheel of a vehicle. The turning shaft is configured to couple the left wheel and the right wheel to each other. A torsion bar is engaged with the turning shaft via a steering gear box. The turning system includes: a turning mechanism including (i) an electric turning mechanism including an electric motor configured to rotate a portion of the torsion bar which is located upstream of the steering gear box and (ii) a hydraulic turning mechanism configured to apply a moving force to the turning shaft in an axial direction, the moving force being produced by a hydraulic pressure; and an electric-motor controller configured to control the electric motor based on a frictional force in the turning mechanism and a road-surface reaction force that acts between (a) a tire on the left wheel and a tire on the right wheel and (b) a road surface.

A turning system is configured to move a turning shaft to turn a left wheel and a right wheel of a vehicle. The turning shaft is configured to couple the left wheel and the right wheel to each other. A torsion bar is engaged with the turning shaft via a steering gear box. The turning system includes: a turning mechanism including (i) an electric turning mechanism including an electric motor configured to rotate a portion of the torsion bar which is located upstream of the steering gear box and (ii) a hydraulic turning mechanism configured to apply a moving force to the turning shaft in an axial direction, the moving force being produced by a hydraulic pressure; and an electric-motor controller configured to control the electric motor based on a frictional force in the turning mechanism and a road-surface reaction force that acts between (a) a tire on the left wheel and a tire on the right wheel and (b) a road surface.

Power steering device has steering mechanism 2, power cylinder 29 having a pair of hydraulic chambers 29a, 29b divided by piston 31 and providing steering force to steering mechanism, torque sensor 11 detecting steering torque Tr of steering mechanism, rotary valve 30 selectively supplying working fluid supplied from pump 9 to the pair of hydraulic chambers according to relative rotation between input and output shafts, hollow shaft motor 10 providing steering force to input shaft, control unit 13 in which microcomputer is mounted, and torque command signal operating section 61 provided in control unit and configured to calculate torque command signal Tm* for driving and controlling electric motor 10 on the basis of the steering torque Tr and vehicle speed Vs and when vehicle speed is a predetermined vehicle speed or greater, set torque command signal to 0. With this, physical size of power steering device can be decreased.

An improved steering shaft assembly is provided. The steering shaft assembly further includes an output shaft that is rotatable with respect to the input shaft. The output shaft includes a rotary valve portion and a longitudinal portion. The steering shaft assembly further includes a torsion bar coupled to the input shaft and coupled to the output shaft distal from the input shaft. The steering shaft assembly further includes a mid-coupler extending around about the longitudinal portion of the output shaft and adapted to cooperate with the rotary valve portion of the output shaft. The steering shaft assembly further includes a screw mechanism extending about the longitudinal portion of the output shaft and adapted to cooperate with the mid-coupler. The screw mechanism is adapted to move laterally relative to the output shaft to maintain transfer of power from between output shaft and the screw mechanism despite misalignments therebetween.

A variable ratio hydraulic steering device with two or more orbit displacers ensures steering with low actuating forces even in the event of a total or partial failure of the oil flow supply. In the event of a total or partial failure of the oil flow supply, the device is capable of switching from one orbit displacer to another, if necessary, independently of the pressure at the inlet connection of the steering device.

A variable ratio hydraulic steering device with two or more orbit displacers ensures steering with low actuating forces even in the event of a total or partial failure of the oil flow supply. In the event of a total or partial failure of the oil flow supply, the device is capable of switching from one orbit displacer to another, if necessary, independently of the pressure at the inlet connection of the steering device.

The invention relates to a hydraulic steering unit (1) including a housing (3), a spool, a sleeve (12) arranged between spool and housing (3), and a measuring motor (14) having a number of working chambers (15), wherein a first commutation geometry (18) and a second commutation geometry (19) are arranged between the sleeve (12) and the housing (3), wherein the commutation geometries (18, 19) are connected to the working chambers (15) of the measuring motor (14) and the housing includes a first direction port (4), a second direction port (5), a pressure port (6), and a return port (7). The object is to have a good steering behavior. To this end one of the commutation geometries (18) is directly connected to the first direction port (4).

The invention relates to a method for compensating a stick-slip effect in the case of a recirculating ball steering system (20) having a steering housing (22), in which a steering piston (24) is supported between a first working chamber (34) and a second working chamber (36), wherein the steering piston (24) has a toothed region (26) on the steering-piston outer wall of the steering position, with which toothed region teeth (28) of a segment shaft (30) mesh, the steering piston (24) can he moved along a longitudinal axis X-X, the working chambers (34, 36) are connected to a control valve (39) by means of pressure-medium lines in order to provide steering assistance, the control valve (39) is connected to a processor unit (40), by means of which valves of the control valve (39) can be actuated, and the processor unit (40) is connected to a sensor (42), which determines rotation of the steering column both in a first direction of rotation and in a second, opposite direction of rotation. When a rotational motion of the steering column in a first direction occurs and thereafter the rotational motion in said direction nearly or completely stops, the valves of the control valve (39) are opened by the processor unit (40) in such a way that the pressure in the working chamber (34, 36) of the steering piston (24) facing away from the direction of motion of the steering piston (24) is reduced and immediately thereafter the pressure in the same working chamber (34, 36) is increased again.

An operating method for a hydraulic servo steering system of a motor vehicle includes a steering cylinder that applies the supporting force to a steering gearing is integrated into a hydraulic circuit by means of a steering valve. The steering valve opening specifies the supporting force, wherein the supporting force is set by the steering valve in accordance with a steering torque applied to a steering wheel, by means of a gearing having play. The steering system further includes an actuator that acts on the gearing in order to cause relative adjustment of the gearing. The opening method provides for a compensation step in which, provided that a steering direction reversal is detected, the gearing is relatively adjusted by means of the actuator in a direction opposite the prior engagement direction of the gearing for a predefined duration or a predefined adjustment distance.

A steering valve includes a housing and a spool disposed inside the housing. The housing includes a top plane and a bottom plane, the top plane including an opening of a first port and the bottom plane including an opening of a second port. The spool includes a top plane including a first and second opening corresponding to a third port and a fourth port, one of which is configured to align with the opening of the first port depending on the orientation of the housing. The spool also includes a bottom plane including a first and second opening corresponding to the third port and fourth port, one of which is configured to align with the opening of the second port depending on the orientation of the housing. The housing is configured to rotate around the spool and wherein the orientation of the housing determines whether the first port is fluidly coupled to the third port via the first opening in the top plane of the spool while the second port is fluidly coupled to the fourth port via the first opening on the bottom plane of the spool or whether the second port is fluidly coupled to the third port via the second opening in the top plane of the spool while the first port is fluidly coupled to the fourth port via the second opening on the bottom plane of the spool.