Steering device
A steering system, e.g., a hydraulic rack and pinion steering system for motor vehicles, includes a steering handle for prescribing a steering intention, a pressure medium source and a control valve device for controlling a flow of pressure medium to and from a servomotor in order to deflect vehicle wheels. The control valve device has a closed center, and a pressure medium accumulator is provided for producing and/or assisting a flow of pressure medium to and from the servomotor.
1. A steering system for a motor vehicle including a hydraulic rack and pinion steering system, comprising
a steering handle configured to prescribe a steering intention and adjustable by a driver,
a rotatably mounted pinion arranged in engagement with an axially displaceable rack,
a control valve device having a closed center,
a hydraulic servomotor including a piston rod drive-connected to the rack and arranged to provide power assistance, the servomotor including two cylinder spaces connected to two cylinder connection on the control valve device via working lines,
a pressure medium source, the pressure medium source and the control valve device configured to provide control of a fluid of pressure medium to and from the servomotor to deflect vehicle wheels,
a pressure medium accumulator configured to produce and/or assist the flow of the pressure medium to and from the servomotor so that the vehicle wheels are steerable at least three times from a first stop to a second stop, if the pressure medium source fails, and,
an electric actuating motor arranged at one end of the pinion, and not positively coupled to the steering handle,
the actuating motor controllable via a control circuit by the steering handle, and is configured to actuate the control valve device.
2. The steering device according to claim 1 , wherein the actuator motor has a redundant configuration.
3. The steering device according to claim 1 , wherein the pressure medium source includes a pump having a non-return valve and an electric motor configured to drive the pump.
4. The steering device according to claim 3 , wherein the pump is arranged as a switchable charge pump for mean energy supply to the servomotor.
5. The steering device according to claim 1 , wherein the pressure accumulator, supplied by the pressure medium source, is configured to reliably ensure energy supply to the servomotor for a parking maneuver.
6. The steering device according to claim 1 , wherein the pressure medium accumulator includes a device configured to sense accumulator pressure.
7. The steering device according to claim 1 , wherein the actuator motor is configured to produce a torque of at most 5 Nm.
8. The steering device according to claim 1 , wherein the pressure medium accumulator is mounted on a steering mechanism.
9. The steering device according to claim 1 , wherein the pressure medium accumulator includes rigid tubes.
10. The steering device according to claim 1 , wherein the control valve device is configured as two seat valves.
11. The steering device according to claim 1 , wherein the control valve device is configured as a rotational slide valve.
12. A steering system for a motor vehicle including a hydraulic rack and pinion steering system, comprising
a steering handle configured to prescribe a steering intention and adjustable by a driver,
a rotatably mounted pinion arranged in engagement with an axially displaceable rack,
a control valve device having a closed center,
a hydraulic servomotor including a piston rod drive-connected to the rack and arranged to provide power assistance, the servomotor including two cylinder spaces connected to two cylinder connection on the control valve device via working lines,
a pressure medium source, the pressure medium source and the control valve device configured to provide control of a fluid of pressure medium to and from the servomotor to deflect vehicle wheels,
a pressure medium accumulator configured to produce and/or assist the flow of the pressure medium to and from the servomotor so that the vehicle wheels are steerable at least three times from a first stop to a second stop, if the pressure medium source fails, and,
an electric actuating motor arranged at one end of the pinion, and not positively coupled to the steering handle,
the actuating motor controllable via a control circuit by the steering handle, and is configured to actuate the control valve device.
13. The steering device according to claim 12 , wherein the driving part and the driven part form one of a recirculating ball mechanism and a recirculating roller mechanism.