Increasing emissions from the common rail is a trend
In the stage of National III standards, diverse technological routes are presented, but solutions such as electronic control combination unit pump and inline pump with EGR can barely meet the National III standards. However, as emission standards become increasingly demanding, the technical bottlenecks of these technologies will become more apparent. In the future, more products will adopt high-pressure common rail systems to increase fuel injection pressure and achieve cleaner exhaust emissions.
Common rail operation
The diesel in the fuel tank is sucked in by the pump, which delivers it to another high-pressure pump. The second pump delivers diesel to the distribution pipe, which is the source of each injector for each cylinder. Diesel is injected into the cylinder at a pressure of 300 to 1600 bar (Toyota engines inject up to 2000 bar, compared to gasoline engines that inject no more than 5 bar). Due to the smaller nozzle, more powdered diesel enters the cylinder (as well as very fine mist), which contributes to spontaneous combustion.
The injection pressure and the possibility of pre injection before the main injection are controlled by the onboard computer to optimize power, consumption, and engine noise based on the engine load and power requirements.
The result of pre injecting diesel before the main diesel in the cylinder is to control the noise level and improve the performance of the engine. Fiat is the company that makes the system more advanced, with its technology called MultiJet, which can send up to 5 previous diesel injections to the cylinder before the main injection, improving control of the mixture and increasing pressure and temperature inside the cylinder.
