| 摘要 |
A power steering system operates with a servo-valve, which responds to the wheel angle of a hand steering wheel, for the operating pressure of a steering system servo-motor and with a modulating valve operating as a function of at least one parameter, in particular the travelling speed. The modulating valve produces a reaction pressure dependent on the parameters by reducing an output pressure derived from the operating pressure. A reaction pressure due to the action on a reaction pressure surface embodied at the valve setting element of the control valve and located in a rection pressure chamber can be felt exclusively, as pressure-dependent feedback, at the hand steering wheel, because the reaction pressure chamber is connected to an operating pressure chamber of the steering system servo-motor and the operating pressure chamber via an associated valve connection of the control valve to an operating pressure source, and, at the same time, the modulating valve is inserted, in series with at least one throttle, between the operating pressure source on one side and a pressure medium return, substantially relieved of pressure, on the other side. The reaction pressure chambers, each connected on one side to an operating pressure chamber, are connected to one another on the other side via a short-circuit pressure connection. To avoid quantities of leakage oil via the modulating valve during relatively low travelling speeds, the short-circuit pressure connection contains a throttle in series with the modulating valve. The modulating valve is inserted in the pressure connection between one reaction pressure chamber and the associated operating pressure chamber. At low travelling speeds, the modulating valve blocks the pressure connection.
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