The Next Generation BOSCH Common Rail Injectors with Digital Rate Shaping – A Key Factor for Meeting Future Requirements

摘要

Over the entire operating map of a Diesel engine there is a complex relationship between fuelconsumption, exhaust and noise emissions. Pilot injections (PI) can be applied to optimizethe combustion process – with the degrees of freedom being limited for conventional PIstrategies. However, these limitations can be overcome by launching the pilot injectionimmediately before the main injection. This digital injection pattern (pilot injection / maininjection) results in a "soft" and uninterrupted combustion process, reducing noise emissionsand permitting a further reduction in emissions and fuel consumption.This Digital Rate Shaping strategy places new requirements onto the injector in terms of thetime interval between pilot injection and main injection, the precision of quantities injected,and reproducibility. Development of the new solenoid-valve injector CRI2-20 which uses anew basic concept with an integral high-pressure volume and a "long-needle" design wastargeted to meet these requirements. This injector's multiple injection features a uniquemetering precision and bears the potential for a further reduction of noise emissions.Combustion concepts with extremely short injection intervals resulting in optimized CO2emissions can be applied to further increase the fuel economy of Diesel engines.The new CRI2-20 by BOSCH is part of a modular range which can be expanded towardshigher injection pressures; thus the advantages and the attractiveness of the Diesel enginecan be further enhanced in the future.