Improved rotary direction control valve for a power assisted steering mechanism

摘要

Rotary direction control valve for power-assisted steering mechanisms of the type comprising coaxial cylindrical elements 32, 33 capable of limited relative rotation about their common axis, in which the internal element 32 is mounted rotatably in the bore of the outer element 33, the latter being mounted rotatably in a fixed housing 30, in which the distribution circuit defined especially by these elements 32, 33 is composed of openings and cavities of fluid connected between a fluid source 15 and a reservoir 17 and which comprises two uptakes for working pressure 18, 19 to make fluid passages of variable cross-section operating by recovery during a limited relative rotation of the said elements 32, 33 and the obtention of a rise in pressure in either of the working pressure uptakes 18, 19, characterised in that the bore 31 of the casing 30, in contact with the external element 33, carries two leakage orifices 43, 44 which emerge into a cylindrical chamber 40 auxiliary to the housing 30, in which the active element 41 of a by-pass passage valve 42 is mounted with displacement, which valve puts the said leakage orifices 43, 44 in communication especially in response to a change of speed of the vehicle. IMAGE