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Electronic Fuel Injection Systems for Heavy-Duty Engines

Posted on 2/15/2016 4:36:04 PM

With the emission rules more and more strictly,lots of the heavy-duty diesel engine manufacturers have to make research and develop the their own electronic fuel injection systems.For example,Caterpillar develop the Hydraulic Electronic Unit Injector (HEUI) and the Mechanically actuated Electronically Controlled (MEUI) systems.Cummins gained the Accumulator Pump System (CAPS), Quantum CELECT, HPI, and XPI injection systems.

In order to meet the demand of lower emissions from diesel engines,the electronically controlled fuel injection systems became the first choice of many engine manufacurers in the late 1980s and early 1990s.Because it could offer the excellent performance.One of the important tool which helps reduce emission from diesel engine is fuel injection timing.It could varies over the speed and load range of the engine.While injection timing could be varied with a purely mechanical approach, electronic control offered a much more flexible and a potentially simpler way to achieve this while also providing the option of introducing a number of other desirable features. We could see Detroit Diesel Series 92 applied the first electronically controlled fuel injection systems in heavy-duty engines in 1985 and series 60 in 1987.While it also appeared in Caterpillar 3176 in 1988.

The unit injectors used in these engines lent themselves well to early adoption of solenoid actuated electronic fuel injectors.Solenoid actuator designs of that period were still relatively large and bulky and a unit injector for a heavy-duty engine provided ample room for it.It took several years for manufacturers to refine the actuator design to make it compact enough to use in common rail systems for light-duty applications and to produce a heavy-duty unit injector, Delphi’s E1 in 2000, which replaced the bulky side mounted actuator with a more compact design that could be integrated into the injector body.
Manufacturer’s quickly learned that electronic control offered not only the ability to control injection timing according to speed and load but also according to the type of driving the vehicle was experiencing. In the 1990s, it was common to program engine controllers to adjust injection timing to optimize fuel consumption in heavy-duty diesel engines when the operating conditions indicated highway cruise conditions. In some cases, this injection timing conflicted with that required to meet regulated emission limits.

As emission regulations continued to tighten, the demands placed on fuel systems increased further and it was not sufficient to simply provide flexibility in injection timing control. Additional drivers that pushed the evolution of diesel fuel injection systems included:
1.Maintaining accuracy of timing and fuel metering over the expected life of the engine placed increased demands on the repeatability of timing and injection quantity and on injector durability.
2.Injection pressures increased to maintain engine thermal efficiency and to enable some reduction in exhaust emissions.
3.Injector response times became faster to allow predictable injection of small injection quantities. This was an important feature to enable multiple injection events.
4.Better control over the opening and closing of the injection nozzle to avoid uncontrolled secondary injections and provide a sharp end of injection. This was also important for enabling multiple injections.
5.Improved mechanical efficiency of the injection system to contribute to the overall goal of improving engine efficiency.

Different engine manufacturers has their own unique fuel injection systems:
1.By cooperation with GM’s Rochester Products Division,Detroit Diesel Corporation develop electronically-controlled unit injector systems
2.Hydraulically-actuated electronically-controlled unit injector system (HEUI) owned by Caterpillar
3.By cooperation with Scania,Cummins develop HPI injection system

In other cases, major heavy-duty engine manufacturers were able to acquire patented technologies and further develop the concepts for their own engine line. An example is the Bendix Diesel Engine Controls unit injector system that was licensed by Cummins and used in the CELECT unit injector.

This article outlines the evolution of electronic fuel injection systems of Cummins and Caterpillar which cover the full range of heavy duty fuel injection systems.Fuel systems suppliers like Bosch,Delphi,Siemens/Continental, Denso,China Balin Parts Plant and others are also familiar in the industry.

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