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The development of a leanburn engine is described, in which optimized engine design, innovative engine management and exhaust gas aftertreatment using a special NOx-storage catalyst were combined to yield a significant improvement in fuel economy with reduced NOx emissions. To achieve stable combustion near the lean limit a swirl system was used and the appropriate parameters of the 2.2 I 4-cyIinder 4-valve SI engine were optimized. As a result, the mixture formation was improved and the lean limit was extended to higher air-fuel ratios. An adaptive lambda controller which was based on the evaluation of engine-smoothness calculated from the RPM-sensor was implemented to control each cylinder individually close to the lean limit. A model-based control system was developed to achieve extremely accurate air-fuel ratio control during transients.

For meeting 21st-century exhaust emission standards for HD diesel engines, new methods are necessary for reducing NOx and PM emissions without increasing fuel consumption. The stratified diesel fuel-water-diesel fuel (DWD) injection in combination with exhaust gas recirculation (EGR) is as a means for NOx and PM reduction without any negative effect on fuel economy. The investigation was performed on a charged HD single-cylinder direct-injection diesel engine with a modern low-swirl combustion system, 4-valve technology and high pressure injection. The application of DWD injection combined with EGR resulted in a 60 percent lower NOx emission at full load and a 75 percent reduced NOx emission at part load when compared with present day (EURO II) technology. This was achieved without any fuel economy penalty, but with an additional PM emission reduction.

Introduction of an array of new electrical and electronic features into future vehicles is generating vehicle electrical power requirements that exceed the capabilities of today's 14 volt electrical systems. In the near term (5 to 10 years), the existing 14V system will be marginally capable of supporting the expected additional loads with escalating costs for the associated charging system. However, significant increases in vehicle functional content are expected as future requirements to meet longer-term (beyond 10 years) needs in the areas of emission control, fuel economy, safety, and passenger comfort. A higher voltage electrical system will be required to meet these future requirements. This paper explores the functional needs that will mandate a higher voltage system and the benefits derivable from its implementation.

Extensive crash sled testing and analysis has recently led to the development of a new HANS prototypes for use in FIA F1. The performance of HANS prototypes has been studied with various conditions of HANS design geometry and impact direction. The new HANS prototypes have been found to substantially reduce injurious motions and forces of the head and neck, and the new HANS is lighter, more compact, and performs better than the currently available HANS. Use of HANS by FIA F1 drivers has been initiated.

Realization of the leanburn SI engine's potential for improved fuel economy strongly depends on precise control of the air-fuel ratio (AFR), especially during transients, for acceptable driveability and low exhaust emissions. The development of an adaptive-feedforward model-based AFR controller is described. A discrete, nonlinear, control-oriented engine model was developed and used in the AFR control algorithm. The engine model includes intake-manifold airflow dynamics, fuel wall-wetting dynamics, process delays inherent in the four-stroke engine cycle, and exhaust-gas oxygen (UEGO) sensor dynamics. The sampling period is synchronous with crank-angle (“event-based”) for more precise control. The controller relies on the engine speed and throttle position for load information. An intake-manifold pressure (MAP) sensor is used for identification of the airflow dynamics, but not for control. The MAP sensor would also be useful for the cold start and for engine diagnostics.

One possibility to improve the fuel economy of SI-engines is to run the engine with a lean air-fuel-ratio (AFR). Hydrocarbon and carbon monoxide after-treatment has been proven under lean operation, but NOx-control remains a challenge to catalyst and car manufacturers. One strategy that is being considered is to run the engine lean with occasional operation at stoichiometry. This would be in conjunction with a three-way-catalyst (TWC) to achieve stoichiometric conversion of the three main pollutants in the normal way and a NOx trap. The NOx trap stores NOx under lean operation to be released and reduced under rich conditions. The trap also functions as a TWC and has good HC and CO conversion at both lean and stoichiometric AFR's. Under lean conditions NO is oxidised to NO2 on Pt which is then adsorbed on an oxide surface. Typical adsorbent materials include oxides of potassium, calcium, zirconium, strontium, lanthanum, cerium and barium.

The use of pistons made of fine grain carbon was investigated in a spark-ignition engine within a European Community funded research project (TPRO-CT92-0008). Pistons were designed and manufactured and then tested in a single cylinder engine. Due to the carbon material's lower coefficient of thermal expansion the top land clearance between piston and cylinder can be reduced by a factor of three in comparison to standard aluminium designs. Under steady-state part-load operating conditions the emission of unburned hydrocarbons can be reduced by more than 15% compared to aluminium pistons, without significant penalties in NOx-emissions. Simultaneously, a small improvement in fuel economy of about 2% is observed. At full-load blow-by leakage flow is reduced by more than 50%. The piston crown temperature is about 30°C higher with the carbon piston than with the standard aluminium piston, due to the lower thermal conductivity of the carbon material.

Some special features of the turbocharged gasoline engine are discussed in comparison with the turbocharged Diesel engine. The influence of compression-ratio, temperature of the charge air, air/fuel-ratio and ignition-timing on combustion, fuel economy and power output is shown. A combined compressor- and engine air-flow-map of the turbocharged gasoline-engine is developed and the features of a compressor matching the special requirements of a TC gasoline engine are deduced from this map. The position of the throttle in the intake-system, which has great influence on governing-qualities and load-change-responce of a turbocharged gasoline engine is discussed and the problems and disadvantages of a waste-gate governed turbocharger especially in connection with a gasoline engine are figured out.

Daimler-Benz considers safety belts as the fundamental and essential restraining system. The company began offering a Supplemental Restraint System option consisting of a driver airbag system and an emergency tensioning belt retractor for the passenger in December 1980. The functional reliability of the system has proven satisfactory.

Among many tasks of car development, safety, economy, environmental benefits and convenience, safety should have a high priority. One of the main goals is the reduction of the number of accidents. Environment and situation recognition by autonomous vehicle-electronic systems can contribute to the recognition of problems together with information to the driver or direct intervention in the car's behaviour. This paper describes some techniques for environment recognition, the status of a present project, and the goals of some PROMETHEUS (Program for a European Traffic with Highest Efficiency and Unprecedented Safety) projects.

The ultimate goal of drive-line management is low fuel consumption as well as providing the highest possible driving performance within the bounds of good driving safety. This can only be achieved by shifting the operating region on the performance diagram. In order to do this the technical characteristics of the drive-line components must be taken into account. The development of drive-line optimization can be separated into two phases. In the first phase the driver is partially or entirely integrated into the control circuit via external visual and acoustic feedback inputs. In the second phase automatic controls take-over the drive-line management without putting stress on the driver so that the vehicle in effect controls itself.

Information on the driving stability can be obtained in the form of oversteer or understeer tendencies and acceleration limits on a circular path. Up to now the calculations have only been made on an ideal, even roadway. Significant dynamic characteristics, such as the tuning of the shock absorbers, which also play a role in evaluating the stability of a vehicle in a driving test, are thereby not included in the calculations. In this paper the unevenness of the roadway is taken into consideration in calculating steady state cornering tests. Different vehicle models can be evaluated in regard to their handling or active safety with the aid of the driver's steering actions required to keep the car on course.

In order to reduce the severity of injuries to pedestrians and cyclists, the sheetmetal contact zones of Mercedes-Benz cars are constructed of a yielding, smooth-surfaced design. Unfortunately, contradictory demands are made on some components. This is particularly true for the bumper in which avoiding or reducing the cost of repair requires a greater bumper height, overhang, and stiffness, which run counter to the requirements of pedestrian protection. Despite this conflict, however, the bumpers of recently developed Mercedes-Benz cars offer a high degree of pedestrian protection since they are faced with rigid foam. To assist in both mathematical and experimental pedestrian impact simulation, standard test dummies should be modified by reducing the stiffness at the waist in order to achieve a higher degree of faithfulness to human behaviour.

Daimler-Benz have developed an automatically/electronically controlled traction system, the 4MATIC. Great store has been set by active safety. This paper deals with the problems involved in 4-Wheel drive and analyzes the reasons which led to the 4MATIC concept. Depending on the conditions encountered, the drive components engage automatically one after the other in the sequence front-wheel drive - interaxle differential lock - rear axle differential lock. The engagement, and thus the approaching limits of driving dynamics, is indicated to the driver by an indicator lamp so that he can adjust to the deteriorated conditions in time. A further important advantage of this system is the automatic disengagement of the differential locks when braking so that the anti-lock braking remains fully effective.

This report deals with the development and use of the Daimler-Benz Isohuman Simulation Model for the mathematical simulation of dummy behaviour in an impact environment. Designated ISM, this computer program package is capable of handling both automobile occupant and pedestrian kinematics. Daimler-Benz safety engineers use the ISM to evaluate new safety designs before performing actual laboratory tests. The ISM code uses the theoretical algorithm of Prof. Wittenburg. The dummy is represented by 11 rigid body elements. Realistic and accurate simulations are assured by the fact that a considerable number of functional and sophisticated algorithms were developed to involve the different interactions of dummy-to-belt or dummy-to-vehicle. In particular, considerable work is being done to introduce a more precise and realistic dummy and vehicle geometry.

Distribution of load has a major influence on type and severity of chest injuries. The introduction of the Hybrid III dummy into crash testing along with the requirement to measure sternum deflection for injury assessment has brought about the need to evaluate how well its thorax senses various loading conditions. Tests revealed that different load distributions, i.e. due to a diagonal shoulder belt or an airbag, did not produce the expected chest deflection patterns. This appears to be the result of both a relatively stiff sternum assembly and a nonsuitable design of the clavicle. Chest compression responses became more realistically when both, sternum and clavicle of the Hybrid II were mounted into the Hybrid Ill's thorax. As a consequence, this study suggests that the thorax of the Hybrid III dummy must be improved.

The risk of head or chest injuries is usually evaluated by means of acceleration measurements using a dummy. Unfortunately, this data provides no information on load distribution over the contact areas which is often related to localized fractures of the bony structure. Therefore, new methods of measuring local forces were developed. 1. Pressure indicating devices attached to a dummy's face are capable of monitoring the local pressure during impact; foil's color change is interpreted by means of digital image analysis. 2. A velocity sensitive viscous tolerance criterion was calculated from the chest compression response of a dummy instrumented with strain gauges on the ribs. The application of advanced techniques in laboratory tests clearly supports the experience of improved protection potential through the use of airbag systems.