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DENSO develops new 2500-bar diesel common rail system; reductions in fuel consumption and emissions

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.



This is a demo of what could have been done with ICEVs years ago.


If it would have been possible, somebody would have done it (why didn´t you do it???). Engine developers were asking for 2500 bar already 20 years ago but nobody could provide it. The second generation of the "pumpedüse" (unit injector) that VW used a couple of years ago, could manage 2500 bar but had so many other drawbacks that it was dropped in favour of common rail. CR systems at that time could cope with only 1800 bar but VW changed to CR nevertheless. Denso is aiming for 3000 bar in the future. In your world, they should introduce it right now, since most likely, they have such systems running the lab already now. However, why do you think they go for “only” 2500 bar today? For sure, they have a number of issues to work on before 3000 bar could be achieved in a reliable way. You seem to lack fundamental understanding about the process of technical development.


VW has announced a variable valve diesel engine delivering 100KW per liter fitted with a 3000 bar injection system along with a 10 speed dual clutch transmission. See the June SAE Automotive Engineering International publication.


I would have to disagree - a demo of what people might have been thinking bout 20 years ago - 1993 - I doubt it.

No-one was thinking about 2500 Bar diesel back then.

This is engineering evolution, grinding away, problem by problem, year by year, and solving them as the controllers get better and faster and a whole host of peripheral innovations/improvements become available at the right price.

Very few people cared about CO2 back then, and oil was cheap at approx $25/barrel. There was little demand for highly efficient engines and it is to the credit of these companies that they remembered the lessons of 1973 and 1979 and kept plugging away at the technologies that we currently use to keep people on the road (in Europe at least).


I have read the same article that you have read. This is something that VW test in the lab and nothing we can expect on the road until a couple of years from now. It is obvious that Denso is testing 3000 bar already in their labs. A HD engine manufacturer tested 3000 bar 20 years ago but still we have not seen any such injection system in production. So, Denso´s 3000 bar system might not be just around the corner. For sure, they have this ambition. So does everybody else. However, it is more likely that they would jack up the pressure in steps of 200-300 bar, with 2-3 years interval between the steps. Thus, we could perhaps expect 3000 bar in about 5 years. The first passenger car Common Rail system was introduced in 1997/1998. It was capable of 1350 bar. 15 years later, we now have 2200 bar. It is not likely that the development would make a giant leap in just no time today. Eventually, the metallic materials we have available today are already stressed to the limit. New materials and design features will of course enable higher pressured but we should not expect something like ~5000 bar in just a few years. Only someone like HarveyD could expect that.

The more we increase the pressure, the more energy is required for injection. Finally, we would reach a point of no return, where this “parasitic” energy loss is higher than the gain due to improvements of combustion. Actually, we did reach this point already a couple of years ago. However, the internal leakage of the fuel injection systems at that time was great, i.e. about as much as the injected fuel (requiring 2x the injected amount of fuel to be pumped). Recent design changes have reduced the leakage to a minimum. Thus, there is again some scope for further increasing the injection pressure. This is just what we see now. From this point we might extrapolate one or two steps further but after that, we are in unknown territory again.

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