Servomotor for braking assistance

Claim 1

A servomotor for braking assistance incorporating: a casing, a piston structure dividing the casing internally into two chambers, distribution valve means situated in a valve body firmly fixed centrally to the piston structure and actuated by an input component to create selectively a differential pressure between the chambers, the valve means incorporating: a plunger mounted so as to slide in the valve body, joined to the input component and defining at one of its ends a movable valve seat, a valve body seat formed in the valve body, concentric with the movable valve seat, valve means mounted in the valve body and elastically pushed towards the valve body seat and movable valve seat, a return spring bearing against the valve body and pushing the input component in the direction opposite to that of the valve body seat and movable valve seat, and a retaining component lying in the valve body and incorporating a first zone co-operating in contact engagement with a shoulder of the plunger and a second zone, outside the valve body, intended to co-operate in abutment with a stationary component firmly fixed to the casing in order to determine, in the configuration of the servomotor at rest, the rest position of the plunger, characterized in that the retaining component is mounted in the valve body so as to pivot about an axis perpendicular to the direction of sliding of the plunger and incorporates a third zone intended, during hinging of the retaining component about the said axis, to co-operate in abutment with a corresponding surface of the plunger in order to determine for the latter a position of maximum retraction relative to the valve body under the effect of the return spring.