US 4,373,598 AGranted

Auxiliary steering for motor vehicles

AssigneeZahnradfabrik Friedrichshafen AG

InventorDieter Elser

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Abstract

A conventional power steering cylinder and valve assembly of the kind having a steering spindle and a torsion rod between relatively rotative valve members is provided with a steering resistance simulating means in the form of a tubular piston that surrounds the torsion rod and axially abuts the manually rotated portion of the steering spindle through a rotation resisting cam device. The reaction piston is axially movable but splined to the torsion rod in a manner to prevent rotation, and subjected to axial pressure force to thus resist manual rotation of the steering spindle. Manual force is exerted to act through the cam device to effect axial movement of the reaction piston against the pressure force thereon to achieve a steering resistance simulation. A particular feature resides in optional use of the reaction piston in an otherwise known cylinder and valve construction, depending on market choice.

Claims19

Dependent claims

In a power steering device comprising a housing having a valved steering spindle therein comprised of two sections connected by a torsion rod (6) for return rotation to a neutral position and wherein one of the sections (1) is manually operable and carries a rotary valve plug (3) and the other of the sections (2) has a valve sleeve (5) encompassing and coacting with said rotary valve plug for flow control to and from pressure chambers (10, 11) within said housing, upon relative rotation of said sections, a piston (13) in said housing movable between said pressure chambers to activate a steering mechanism, and drive means (W, etc.) intermediate said valve sleeve section and said piston;

the improvement residing in road resistance simulating means which comprises:
a reaction piston (20) encompassing said torsion rod within said valve sleeve section and having an end adjacent an end of said steering spindle and rotation resisting means (21, 22, 25) comprising cam means intermediate said adjacent ends;
and force means (30) acting on said reaction piston in axially spaced relation to said cam means remote from the rotary valve plug for exerting force against said steering spindle through said cam means upon rotation of said steering spindle to resist rotation thereof.

the improvement residing in road resistance simulating means which comprises:
a reaction piston (20) encompassing said torsion rod within said valve sleeve section and having an end adjacent an end of said steering spindle and rotation resisting means (21, 22, 25) comprising cam means intermediate said adjacent ends;
and force means (30) acting on said reaction piston in axially spaced relation to said cam means remote from the rotary valve plug for exerting force against said steering spindle through said cam means upon rotation of said steering spindle to resist rotation thereof;
said valve section having a tubular end portion enclosing a reaction chamber;
said reaction chamber having a portion of said torsion rod therein;
sets of complementary opposed retaining grooves arrayed respectively in said reaction chamber and in said torsion rod and ball bearings retained in said grooves to maintain said reaction piston non-rotational relative to said torsion rod and to effect ease of axial motion of said reaction piston wherein at least one of said set of grooves is axially elongated.

3 more elements

In an auxiliary fluid power steering mechanism including a steering spindle assembly (1) formed by a manually rotatable plug valve section (3), a driving sleeve section (2) having a valve control portion (5) axially aligned with the plug valve section, a torsion rod (6) having opposite end portions (23, 24), means (26, 28) coupling said opposite end portions to the plug valve section and the sleeve section, respectively, and an operating piston (13) drivingly engaged with the sleeve section, the improvement comprising a tubular reaction piston (20) enclosing the torsion rod and connected thereto at one of the opposite end portions (24) thereof remote from the plug valve section of the spindle assembly, complementary cam surfaces (21, 22) respectively formed on the plug valve section and the tubular reaction piston at said other of the opposite end portions of the torsion rod, a plurality of ball elements (25) axially spacing the cam surfaces radially between the sleeve section and said other of the end portions of the torsion rod, and means (30, 31) for exerting an axial centering bias on the reaction piston at said one of the opposite end portions of the torsion rod to maintain the cam surfaces in parallel spaced relation.

Dependencies are inferred from the claim text.