Power-assisted steering system

Claim 2

A power-assisted steering system for a motor vehicle such as an automobile and truck for travel over a roadway, the vehicle including a wheel carrier assembly having wheels rotatably journalled thereon and a steering wheel assembly having a steering wheel on which forces act and to which a driver of the vehicle applies a steering wheel torque (m LR ) when manipulating the steering wheel assembly for steering the vehicle, the wheels being subjected to mechanical reaction from the roadway travelled on by the vehicle, the power-assisted steering system comprising: a servo drive operatively connected to said wheel carrier assembly for articulating said wheels whereby an actuating torque (m Lenk ) is developed between said servo drive and said wheel carrier assembly; steering wheel torque supply means for supplying a first signal indicative of the steering wheel torque (m LR ); actuating torque (m Lenk ) supply means for supplying a second signal indicative of said actuating torque (m Lenk ); and, controller means receiving said first and second signals to form a control difference (r d ) and for controlling said forces acting on said steering wheel to predetermined values while considering the mechanical reaction from the roadway.

Claim 3

The power-assisted steering system of claim 1, wherein the values for the steering wheel torque (m LR ) are influenced in dependence upon road and driving conditions by means of a set of characteristic curves.

Claim 4

The power-assisted steering system of claim 1, wherein the values of the steering wheel torque (m LR ) are influenced in dependence upon vehicle and road conditions by means of an algorithm of an evaluating circuit.

Claim 5

The power-assisted steering system of claim 1, wherein said steering wheel torque (m LR ) defines an actual value for said controller means and said actuating torque (m Lenk ) defines a desired value for said controller means.

Claim 6

The power-assisted steering system of claim 1, wherein the actuating torque (m Lenk ) defines an actual value and the steering wheel torque (m LR ) defines a desired value for said controller means for a self-acting return movement of the wheel carrier assembly.

Claim 7

The power-assisted steering system of claim 1, wherein the vehicle travels at a road speed (V F ) along the roadway; and, an evaluation circuit is connected upstream of said controller means and said evaluation circuit being influenced by the road speed (V F ) of the vehicle.

Claim 8

The power-assisted steering system of claim 1, further comprising a dynamic controller connected in parallel to said controller means; said first and second signals being applied to said dynamic controller as respective input variables.

Claim 9

The power-assisted steering system of claim 1, said servo drive including a servo motor having a moment of inertia and said system further comprising a secondary servo motor speed controller for eliminating the moment of inertia of the servo motor.

Claim 10

The power-assisted steering system of claim 8, further comprising a linearization circuit connected downstream of said secondary servo motor speed controller.

Claim 11

The power-assisted steering system of claim 9, further comprising an actuator for driving said servo motor; and, said actuator including a current control loop.

Claim 12

The power-assisted steering system of claim 1, said servo drive being hydraulic.

Claim 13

The power-assisted steering system of claim 1, said servo drive being electro-mechanical.

Claim 14

A power-assisted steering system for a motor vehicle such as an automobile and truck for travel over a roadway, the vehicle including a wheel carrier assembly having wheels rotatably journalled thereon and a steering wheel assembly having a steering wheel on which forces act and to which a driver of the vehicle applies a steering wheel torque (m LR ) when manipulating the steering wheel assembly for steering the vehicle, the wheels being subjected to mechanical reaction from the roadway travelled on by the vehicle, the power-assisted steering system comprising: a servo drive operatively connected to said wheel carrier assembly for articulating said wheels whereby an actuating torque (m Lenk ) is developed between said servo drive and said wheel carrier assembly; steering wheel torque supply means for supplying a first signal indicative of the steering wheel torque (m LR ); actuating torque (m Lenk ) supply means for supplying a second signal indicative of said actuating torque (m Lenk ); controller means receiving said first and second signals to form a control difference (r d ) and for controlling said forces acting on said steering wheel to predetermined values while considering the mechanical reaction from the roadway; a summing point connected to the input of said controller means; an evaluation circuit connected to said summing point; and, said second signal being applied as an input to said evaluation circuit and said evaluation circuit being configured to supply a characteristic torque as an output variable to said summing point to form said control difference (r d ).

Claim 15

A power-assisted steering system for a motor vehicle such as an automobile and truck for travel over a roadway, the vehicle including a wheel carrier assembly having wheels rotatably journalled thereon and a steering wheel assembly having a steering wheel on which forces act and to which a driver of the vehicle applies a steering wheel torque (m LR ) when manipulating the steering wheel assembly for steering the vehicle, the wheels being subjected to mechanical reaction from the roadway travelled on by the vehicle, the power-assisted steering system comprising: a servo drive operatively connected to said wheel carrier assembly for articulating said wheels whereby an actuating torque (m Lenk ) is developed between said servo drive and said wheel carrier assembly; steering wheel torque supply means for supplying a first signal indicative of the steering wheel torque (m LR ); actuating torque (m Lenk ) supply means for supplying a second signal indicative of said actuating torque (m Lenk ); controller means receiving said first and second signals to form a control difference (r d ) and for controlling said forces acting on said steering wheel to predetermined values while considering the mechanical reaction from the roadway; a summing point connected to the input of said controller means; an evaluation circuit connected to said summing point; and, said second signal being applied as an input to said evaluation circuit and said evaluation circuit being configured to supply a characteristic torque as an output variable to said summing point to form said control difference (r d ).

Claim 16

The power-assisted steering system of claim 13, further comprising damping circuit means for supplying a damping torque (m d ) to said summing point for influencing said control difference (r d ).

Claim 17

The power-assisted steering system of claim 14, wherein at least one of the following are applied to said damping circuit means for influencing said damping torque (m d ); said actuating torque (m Lenk ), said steering velocity ( L ) and said road speed ( F ).