Zf Friedrichshafen Ag

Zf Lenksysteme Gmbh

Zf Friedrichshafen

Werner Breitweg

Rainer Sch&auml;nzel

Arthur Rupp

Alfred Brenner

Hans Hofmann

J&uuml;rgen Bieber

Bernd Koziara

Jurgen Bieber

A technique for manufacturing a gear rack ( ) for a rack-and-pinion steering gear for automobiles makes use of a blank ( ) for the gear rack ( ) having at least in the latter's toothed area a form deviating from a circular cylinder. Size and form of the cross-section of the blank ( ) are selected in a manner that the contour of the finished gear rack ( ) in the toothed area ( ) does not project beyond the envelope given by the dimensions of neighboring parts of the rack-and-pinion steering gear. The gear rack ( ) is formed from the blank ( ) by means of tumble-forging. After tumble-forging, the gear rack ( ) in its toothed area ( ) outside the toothed section has a convex or concave longitudinal profile, which serves to support the tumbling torques during tumble-forging.

Method for producing a rack

A rotary slide valve for power-assisted steering systems of motor vehicles includes a rotary slide which is connected fixedly in terms of rotation to a valve input member. The control bush is connected fixedly in terms of rotation to a valve output member. The two valve elements are arranged so as to be movable coaxially one in the other and are rotatable relative to one another at most by the amount of the rotary travel of a backlash coupling. The rotary slide has outer and the control bush inner longitudinal control grooves which cooperate with one another in order to control a pressure medium to and from two working spaces of a servomotor. The rotary slide is connected to the valve output member via a torsion-bar spring. Production-related tolerances which may lead to undesirable effects in driving behavior are compensated by a connecting element.

Rotary shift valve for servo-assisted steering systems of motor vehicles

A rotary shift or slide valve (,) for power steering systems of motor vehicles contains a rotary slide (,) linked to a valve input element (,). A control bush (,) is guided in an axial bore (,) of the rotary slide (,) and rotatable by a limited angle. The control bush (,) forms a rotation-fixed link with a valve output element (,). Between the rotary slide (,) and the valve output element (,), there is a centering device, which contains two centering elements (,), which can be rotated against each other, and at least one anti-friction element (,) located between the two centering elements (,). One of the centering elements (,) forms a fixed link with the reaction piston (,) and a rotation-fixed but axially displaceable link with the valve output element (,) via a metal bellows (,). The other centering element (,) forms a rotation-fixed and non-displaceable link with the rotary slide (,). The reaction piston (,) in the area of the centering device is arranged radially around the rotary slide (,) and projects in axial direction into the area of the rotary slide (,). As a result of this intra-positioning of components, the axial length of the rotary shift valve is reduced.

Rotary slide valve for power assisted steering of motor vehicles

Toothed-rack power-assisted steering in particular for motor vehicles

Rotary slide valve for power-assisted steering in motor vehicles

A centering device for steering valves which includes a rotary rod (1) that is firmly connected at an endpiece (1A) with a drive shaft (3) and at another endpiece (1B) with a power takeoff shaft (4). Fine-centering is provided because rotary rod (1) cannot establish any exact mid-way centering between a rotary slide (3A) and a valve bushing (6). The fine-centering device consists of a tube-shaped endpiece (7) that is attached to the drive shaft and that bears a metal bellows (8) and a centering piece (10) that is connected with the bellows. Centering piece (10) is axially prestressed by metal bellows (8) and, via roller bodies (12) presses against another centering piece (14). Centering piece (14) is part of a bearing race (15) of a needle bearing (16) that is pressed upon the endpiece (1B) of rotary rod (2), the endpiece (1B) being connected to the power takeoff shaft (3). The centering pieces (10, 14) are provided with oblique-surface grooves (11, 13) that--when the two shafts (3, 4) are twisted toward each other--generate a centering force via the roller body.

Centering device, especially for steering valves

Rotary slide valve for auxiliary power steering systems in motor vehicles

Growing community of inventors

Bargau, Germany

Werner Breitweg