Power-assisted steering device

Claim 1

In a power-assisted steering device for a vehicle, comprising control means acting on steering means, said control means incorporating a transmission element in two parts which parts are capable of limited relative angular displacement under the action of the said control means, and auxiliary assistance means operable to act on the steering means in the same direction as the control means in response to said relative angular displacement, the said auxiliary assistance means comprising a hydraulic power system including means for pressurizing a hydraulic fluid and a fluid reservoir, a hydraulic actuator acting on the said steering means, and a hydraulic distributor interposed between the power system and the actuator, the said distributor comprising an axially-stacked assembly composed of a first stator, a first rotor plate integral in rotation with one of said two parts of the transmission element, a second rotor plate integral in rotation with the other said part of the transmission element, and a second stator, said assembly comprising said first stator, said first rotor, said second rotor and said second stator stacked in side-by-side relationship with their side faces contiguous to each other, the said rotor plates having a series of hydraulic passages for feeding and returning fluid to and from the actuator by the power system via the stators; the improvement comprising at least one pressure-equilibrating channel, in which no liquid circulates, in at least one of the rotors, said channel emerging through at least one of the faces of this rotor in an occluded region of at least one of the adjacent faces of the rotor and stator that are on opposite sides of said at least one rotor.