Daimler Chrysler Ag

Other

Mercedes-benz Aktiengesellschaft

Daimchrysler Ag

Daimler Ag

Mathias Hartl

Hubert Bohner

Martin Moser

Reinhold Schneckenburger

Rainer Freitag

Gerhard Kurz

Harry Troester

Joachim Gloger

Wolfgang Schrock

Wilfried Huber

Lars Krüger

Tobias Speidel

Andreas Platte

Stefan Franz

Matthias Reichmann

A steering system functions in accordance with the &ldquo;steer by wire&rdquo; concept and has a normal operating system without positive coupling between the steering handle and the steered vehicle wheels, as well as an emergency operating system, which functions with positive coupling between the steered vehicle wheels and the steering handle. An auxiliary operating system is additionally provided, which, in response to malfunctions of the normal operating system, assumes its tasks and, in a transitional phase, adapts the performance characteristics of the steering system to those of the emergency system, which is switched on upon conclusion of the transitional phase. Thus, at the transition from the normal operating system to the emergency operating system, the driver is given time to become accustomed to the other steering performance.

Steering system for motor vehicles

Control system for brake power proportioning on a road vehicle

A way is provided to simulate the steering handle manual torques which correspond to a steering stop of the steered vehicle wheels for a vehicle steering system which can be operated in a normal mode and in an emergency mode. The steering system is capable of being switched between a steer-by-wire level assigned to the normal mode, on which level a steering handle is connected to steered vehicle wheels via an electric or electronic control system, and a fall-back level assigned to the emergency mode, on which level the steering handle is positively coupled mechanically and/or hydraulically to the steered vehicle wheels. The fall-back level is activated in normal mode if the steered vehicle wheels are displaced into the region of the steering stop.

Method for operating a vehicle steering system

A steering system for vehicles can be operated in a normal mode, in which a steering handle actuated by the driver and steered vehicle wheels are connected to one another via a control system, and in an emergency mode, in which the steering handle and the steered vehicle wheels are positively coupled. To achieve a steering system which increases the operational reliability of the steering system by simple design measures, a steering-angle control unit for a steering-angle actuator actuates the steered vehicle wheels. The control unit contains a first steering-angle control system, and a manual-torque control unit for a manual-torque actuator actuates the steering handle for the purpose of simulating manual torques. The control unit also contains a first manual-torque control system, and the steering-angle control unit comprises a second manual-torque control system, which is connected redundantly with the first manual-torque control system of the manual-torque control unit. The manual-torque control unit comprises a second steering-angle control system which is connected redundantly with the first steering-angle control system of the steering-angle control unit.

Steering system for a vehicle

High functional reliability for a vehicle steering system that can be switched between a normal mode with a steer-by-wire level and an emergency mode with a fall-back level is achieved by providing that the fall-back level has a hydraulic system which contains a manual-side double-acting piston-cylinder unit which is actuated with a steering handle, e.g. steering wheel. The unit is positively coupled hydraulically to a wheel-side double-acting piston-cylinder unit which actuates steered vehicle wheels. A hydraulic charging system has a hydraulic pump, the inlet side of which is connected to a hydraulic-fluid reservoir. Switchable hydraulic couplings are provided for hydraulically coupling and decoupling the hydraulic system of the fall-back level and the hydraulic charging system to and from one another, respectively.

A moved mass of hydraulic medium is used as a compensating mass at critical frequencies of the suspension system to achieve a frequency-selective dynamic damping, and a suitable hydraulic transmission ratio can ensure that a relatively small quantity of hydraulic medium is moved at high speed in order to achieve a good compensating effect, despite the low mass of moved hydraulic medium. A displacement unit can be connected to the sprung mass via an elastic bearing part and to the associated spring accumulator via a hydraulic line. The spring constant of the bearing part, the mass of that part of the displacement unit or of the spring unit mounted on the bearing part, the cross-section of the hydraulic line and its length, the effective cross-section of the displacement unit and the density of the hydraulic medium are so sized that the resonant frequency of the spring unit is near a critical frequency of the suspension system, for example near the frequency of the axle resonance of a vehicle. Alternatively, the displacement unit can be connected to a first spring accumulator which is connected to a second spring accumulator via a hydraulic channel. The length and cross-section of the channel are so coordinated with the density of the hydraulic medium and with the characteristics of the spring accumulators that the natural frequency of vibrations of the fluid mass in the channel coincides at least approximately with one of the critical frequencies of the suspension system.

Motor vehicle suspension system

Growing community of inventors

Kernen, Germany

Mathias Hartl