求翻译：世界性大公司研究开发和生产的共轨喷油系统，其基本原理大同小异，但在一些关键零部件的设计上则各有特色。BOSCH公司对共轨喷油技术的研究与开发1997年才起步，但是发展迅速，现在已经发展到了第四代，累计已经生产出了大约1500万套共轨燃油喷射系统。是什么意思？

Global research and development and production of common rail injection system, whose basic principle similar, but in some of the key components of the design have their own characteristics. bosch company research and development of common rail fuel injection technology in 1997 to start, but the rap