|Components of the new 2500-bar DCR system. Click to enlarge.
Global automotive supplier DENSO Corporation has developed a new 2500-bar diesel common rail (DCR) fuel injection system; DENSO says this is the currently the world’s highest injection pressure for a diesel common rail fuel injection systems comprising injector, fuel pump and common rail.
Based on DENSO’s research, the new system can help increase fuel efficiency by up to 3% while also reducing particulate matter (PM) by up to 50% and NOx by up to 8%. This is compared to DENSO’s previous generation system. The new DCR system will launch later this year on passenger, commercial, agricultural and construction vehicles worldwide.
|Common rail systems
|In a DCR, the fuel—highly compressed by the fuel pump—is stored in an accumulator called a common rail. Then it is sprayed through the electrically controlled injectors into the combustion chambers.
|Storing highly compressed fuel in the common rail not only further increases the pressure of the fuel but also controls fuel injection pressure and timing without being effected by the engine’s rotation speed.
In a common rail system, a portion of the fuel delivered from the fuel pump to the injectors is used for purposes such as lubricating system components. That fuel is then returned back to the fuel tank, which puts an additional load on the fuel pump, instead of being injected into the engine combustion chambers.
By improving the design structure of the injector, fuel pump, and common rail, DENSO significantly decreased the workload of the fuel pump by reducing the amount of fuel that was sent back to the fuel tank by about 90%.
To generate a higher fuel injection pressure, DENSO redesigned components and used new materials. These changes allowed the fuel to atomize into finer droplets, which improved fuel ignition and combustion efficiency, resulting in increased fuel economy and cleaner exhaust emissions.
As automakers have limited space for component integration, DENSO was able to engineer and manufacture a fuel pump that is similar in size but more efficient than the previous system. DENSO was able to accomplish this by reducing the workload of the fuel pump.
DENSO was the first to commercialize diesel common rail systems in 1995. In 2002, DENSO offered an 1800 bar common rail system, the world’s highest injection pressure at the time. In 2008, DENSO released a 2,000 bar model into the market.
In 2012, DENSO commercialized the engine control system called intelligent-Accuracy Refinement Technology (i-ART), in which the injectors have a built-in pressure sensor to measure fuel injection pressure in real time and control the fuel injection quantity and timing of each injector. (Earlier post.)
DENSO is working to develop and commercialize a 3000-bar diesel common rail system. The company will continue to develop products and technologies that help improve the performance of diesel-powered vehicles to reduce its impact on the environment.