Water injection improves engines

摘要

Bosch is developing a water injection system that should increase efficiency in gasoline engines, improving performance on the NEDC test cycle by 4%. The supplier wants to address the compromise between part-load efficiency and performance and efficiency at full-load conditions. Bosch's board member for mobility solutions, Dr Rolf Bulander, said: "Current engines typically retard ignition timing at high loads to avoid knocking. This leads to a loss in fuel efficiency, reduced engine power, and increased exhaust-gas temperatures. Water injection can mitigate these drawbacks, if not remedy them completely." The firm has developed the technology to improve knock-limited operation areas such as the reduction of fuel consumption at high loads and low speeds and the reduction or avoidance of fuel enrichment and lower exhaust-gas temperatures at high loads and high speeds. Both effects result in lower CO_2 emissions in real driving conditions. The reduced knock tendency can also be used to increase engine compression, which has additional benefits at part load. It also results in lower fuel consumption and reduced CO_2 emissions in the NEDC and WLTC test cycles.