Modified solenoid-valve injectors
The modular concept of the CRS2 common-rail system with solenoid-valve injectors covers the range from two- to eight-cylinder engines. Apart from the tried and true CRS2-16 and CRS2-18 models, which deliver 1,600 and 1,800 bar respectively, the system is now also available in a CRS2-20 version, delivering 2,000 bar. Higher injection pressure vaporises the fuel in the combustion chamber even more finely. This optimises combustion, thus reducing emissions and fuel consumption. Moreover, in the newly developed CRI-20 solenoid-valve injector, an integrated high-pressure reservoir is used for the first time. This reduces fluctuations in pressure. All CRS2 injectors allow a wide dynamic range when controlling the nozzle needle, and thus make short intervals between injections possible. That allows up to eight individual injections per cycle. Advance injection reduces combustion noise and NOx emissions, and post-injection reduces particulate emissions. For some applications, the CRS2 common-rail system can already be designed to meet the Euro 6 emission standard, which will come into effect in 2014. Especially for the Asian growth markets, and in particular India and China, Bosch continues to offer its CRS1-14UP and CRS1-16, which are especially robust and cost-effective solenoid-valve systems featuring injection pressures of 1,450 and 1,600 bar.
Piezo injectors: up to 2,500 bar in the future
The technically more complex CRS3 common-rail system with piezo injectors is designed for engines with very high specific power of more than 75 kilowatts per litre of displacement. It works in combination with the CP4 high-pressure pump and is so far available for system pressures of 1,800 and 2,000 bar. However, Bosch engineers are already working on systems with up to 2,500 bar. The piezo actuator develops some ten times more power than a solenoid valve, and is thus less sensitive to minor fuel impurities. For precisely metering the tiniest amounts for advance and post-injection, as well as for consistent quality over its service life, the inline piezo injector satisfies the highest standards. Thanks to its modular design, this system can be adapted to the requirements of engines with between four and twelve cylinders.
Diesel engines: fit for the future with Bosch technology
Modern diesel engines equipped with Bosch high-pressure injection systems have the potential to fulfil future emissions standards. All Bosch’s current common-rail systems can be combined with eco-friendly additional features such as start-stop. In addition, they work with the new downsized engines that automakers are increasingly bringing to market.