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Wheel slip control system have found a remarkable penetration in all car segments. The information on the wheel behavior has lead to further developments which control the brake performance as well as the driving of the car in general. Latest systems introduced especially on luxury cars use wheel individual brake intervention to ensure vehicle stability under various driving maneuvers within the physical limits. Such systems use vehicle dynamic sensors and special hydraulics which serve as energy source for the automatic brake application. The technical effort of such systems like the Dynamic Stability Control DSC has limited the installation to upper class cars so far. New approaches are required to allow for a more wide spread penetration. Optimized hydraulics together with a rational design of the electronics seems to offer a basis for a more cost effective design.

Noise emitted from the pump can be a major influence on the overall noise created by a power steering system. Dynamic simulation can aid the designer by showing the effect of the pump geometry and oil properties on noise before the prototype has been built. This paper discusses a simulation of suction port flow ripple in a power steering vane pump, which is validated against experimental data. Results show that the mean pressure in the delivery line affects the amplitude of suction port flow ripple. Internal leakage in the pump was found to have little effect on suction port flow ripple. The level of high-frequency flow ripple from the suction port was found to be comparable with or greater than that from the delivery port. The simulation is used to recommend the addition of relief grooves to reduce the high-frequency flow ripple.

BMW, DaimlerChrysler, Motorola and Philips present their joint development activity related to the FlexRay communication system that is intended for distributed applications in vehicles. The designated applications for powertrain and chassis control place requirements in terms of availability, reliability and data bandwidth that cannot be met by any product currently available on the market under the testing conditions encountered in an automobile. A short look back on events so far is followed by a description of the protocol and its first implementation as an integrated circuit, as well as its incorporation into a complete tool environment.

The Milner CVT is a patented [1] rolling traction transmission offering advantages of high power density and simplicity of construction and operation. A 90 mm diameter prototype variator is described which was sized for a maximum rated input power of 12 kW. Experimental data are presented demonstrating high efficiency and low shift forces. Resistance to overload torque is shown to be exceptional and preliminary durability trials indicate a highly viable concept for series production. Based upon the measured data, characteristics of larger variators are predicted and prospects for automotive applications discussed.

A joint study was conducted between BMW and Goodyear with the objective of analysing the cause and identifying methods to reduce the structure-borne interior noise in a vehicle driving on rough road surfaces. A vibro-acoustic characterization of the car was performed by measuring the car vibro-acoustic transfer functions and by using a transfer path analysis technique to identify the main suspension parts affecting the interior noise at target frequencies. The vibration transmissibility characteristics of the tire were measured and also simulated by Finite Element in [1-200Hz] frequency range. The vibro-acoustic interaction between the tire and car sub-systems was examined. A Finite Element sensitivity analysis was used to define and build new prototype tires. A 3dB(A) interior noise improvement was obtained with these new tires at target frequencies.

The first part of the paper describes the brake system of the BMW 850i including brake actuation, brake split and ABS. ABS control philosophy and components are presented as well as performance date are shown. The BMW 850i will be available with two Automatic Stability Control systems ASC und ASC+T which are explained more in detail. Special attention is payed to the electronic and hydraulic interfacing of the different sub-systems required for ABS and ASC.

The design of quiet power steering vane pumps requires accurate experimental and analytical tools to assess fluidborne noise. Measurement of vane pump fluidborne noise-generating potential must minimize hydraulic circuit effects. The difficulties of distinguishing between pump and hydraulic circuit effects is discussed. A technique called the “secondary source” method for measuring positive displacement pump flow ripple is described. The technique allows evaluation of the pump discharge impedance and flow ripple based on the analysis of the wave propagation characteristics in a special test circuit. This test method is used to validate a computer model of the vane pump flow ripple at the rotating group discharge. The model computes the vane chamber pressure histories which are used to obtain net discharge flow ripple. Geometric definition is kept flexible in the model so that compression and leakage can be evaluated for any vane pump design.

For the first time in volume production, supporting welded aluminum structures were used in the chassis area. Metal sheets, extruded sections, longitudinally seam welded pipes and castings were used as semi-finished products. Extensive strength tests, in cooperation with the Design Department and Production, resulted in sophisticated design solutions. In considering matters important to the customer, these solutions were substantiated through numerous examinations which are especially necessary for aluminum.

Driver behaviour can strongly affect fuel consumption, and driver training in eco-driving techniques has been shown to reduce fuel consumption by 10% on average. However the effects of this training can be short-lived, so there is an apparent need for continuous monitoring of driver behaviour. This study presents a driver advisory tool which encourages eco-driving, and its evaluation in the field. The system, developed by Ashwoods Automotive Ltd (UK) and the University of Bath (UK), is aimed at fleet operators of light commercial vehicles, where the driver is typically a company employee. A significant strength of the system is that it has been designed for easy integration with the vehicle CAN-bus, reducing complexity and cost. By considering the Inertial Power Surrogate (speed times acceleration) the core algorithm is able to identify behaviour which is likely to increase fuel consumption.

The reduction of fuel consumption in vehicles remains an important target in vehicle development to meet the carbon dioxide emission reduction target. One of the significant consumers of energy in a vehicle is the hydraulic power-assisted steering system (HPS) powered by the engine belt drive. To reduce the energy consumption an electric motor can be used to drive the pump (electro-hydraulic power steering or EHPS). In this work a simulation model was developed and validated to model the energy consumption of the whole steering system. This includes an advanced friction model for the steering rack, a physically modeled steering valve, the hydraulic pump and the electric motor with the control unit. The model is used to investigate the influence of various parameters on the energy consumption for different road situations. The results identified the important parameters influencing the power consumption and showed the potential to reduce the power consumption of the system.

The new generation of drive-by-wire systems currently under development has demanding requirements on the electronic architecture. Functions such as brake-by-wire or steer-by-wire require continued operation even in the presence of component failures. The electronic architecture must therefore provide fault-tolerance and real-time response. This in turn requires the operating system and the communication layer to be predictable, dependable and composable. It is well known that this properties are best supported by a time-triggered approach. A consortium consisting of German and French car manufacturers and suppliers, which aims at becoming a working group within the OSEK/VDX initiative, the OSEKtime consortium, is currently defining a specification for a time-triggered operating system and a fault-tolerant communication layer.1 The operating system and the communication layer are based on applicable interfaces of the OSEK/VDX standard.

Integrated Chassis Management ICM is a novel and demanding approach to develop a vehicle chassis and all its control systems in a common process which explicitly addresses the interrelations between them. Primary aims are the improvement of driving safety and comfort by creating synergies in the use of sensor information, hardware, and control strategies. The Electronic Brake Management EBM is an essential part of ICM and an important step to its development.