Gerhard Stumpp

Common Rail - An Attractive Fuel Injection System for Passenger Car DI Diesel Engines

Passenger car DI Diesel engines need a flexible fuel injection system. Bosch developed a common rail system for this purpose. Besides variation of fuel quantity and start of injection, it allows choosing injection pressure in the range of 150 to 1,400 bar and injecting fuel in several portions. These new means will contribute to further improvements of DI engines concerning noise, exhaust emissions and engine torque.

An Exhaust Gas Recirculation System for Diesel Engines

The paper describes an EGR-system for diesel engines which senses the air-flow and the fuel-flow of the engine and limits the EGR-rate so, that the air-fuel-ratio is lean enough for a clean combustion. Furthermore the paper shows the emission results which have been obtained with the described EGR-system on different diesel passenger cars.

STRATEGY FOR A FAIL-SAFE ELECTRONIC DIESEL CONTROL SYSTEM FOR PASSENGER CARS

Mechanical control systems for diesel engines are reliable and exhibit a low failure rate. However, rising demands for improved functional characteristics and closer tolerances require electronic diesel control. The electronic diesel control (EDC) offers functional advantages over mechanical controls. In order to obtain a fail-safe system it is necessary to detect defects in sensors, in the digital processor, in actuators and in the overall system. The failure of exhaust gas recirculation is uncritical, the failure of start of injection control needs countermeasures to avoid a damage of the engine. Without countermeasures fuel delivery control failure may lead to safety risks. All required countermeasures will be explained in detail.

Fuel Injection Equipment for Heavy Duty Diesel Engines for U. S. 1991/1994 Emission Limits

The particulate emissions can be reduced by increasing injection pressure. The NO/sub chi/ -emission can be lower to the required amount with a retarded injection-begin. These measures raise fuel consumption by approximately 8 - 10%. To avoid blue smoke from the cold engine, it is advantageous that the fuel injection is advanced during the warm-up period. These statements apply for injection systems with unit injectors as well as for pump-line-nozzle-systems. In this paper, the pump-line-nozzle-system will be described. With this system, injection pressures of 1200 to 1400 bar at the injection nozzle are reached. The injection-begin can be changed with a control-sleeve in-line pump. The injection-begin and fuel quantity can be flexibly and accurately adjusted by means of an electronic governor.