Common Rail
Injection (DCI) systems make diesel leaner, meaner and greener.
Compact Recreational Vehicles (CRVs) are trimming down in size and producing more efficient engine power. Major automakers are manufacturing new models using Diesel Common Rail Injection (DCI) systems for fuel injection. DCI is a systemic way of channeling more pressurized fuel loads into multiple, customized doses. An electronic monitor maintains common pressure, while improving fuel atomization in each engine cylinder. The bottom line is power, efficiency and stability for CRVs.
Controller
The backbone of CDI injection systems is a single automated controller, or pump, that governs the time, quantity and pressure of fuel injection events, according to Automotive Diagnostics and Publishing. Generally, automated control is aimed at reducing noise and emissions while fuel is being injected to the engine valves. In older, cam-driven engines, the duration and pressure of all injection was based on the parameters of each singular combustion event. The older systems applied generic fuel injection to engine valves regardless of combustion variables. By design, clean diesel fuel injection addresses each engine cylinder with its own injector.
Injection Array
A "fuel injection event," the process of injecting fuel to the engine cylinder, is a three-stage process in CDI systems. "Pilot" injections occur just before the main "event" is administered to a cylinder, followed by a "post" injection -- a final top-up supply. CDI contains three injections per event, per cylinder as detected by electronic monitor while fuel circulates through the CR-V's diesel engine. Common Rail Diesel engines allow controllers to apply specific quantities of injection based on variations in fuel performance. CDI systems can perform up to four fuel injections per engine stroke, according to Transport Canada.
Sustained Pressure
Prior to CDI, fuel injection pressures were dictated by engine speed, according to Automotive Diagnostics and Publishing. The highest fuel injection occurred at the highest speed, and fuel injection declined as a vehicle slowed. Common Rail Injection (DCI) systems monitor fuel valve pressure, limiting that pressure in the "common rail" pipe. Instead of opening fuel injectors with preloaded springs (as in the past), DCI engines store up to 29,000 pounds per square inch (psi) of fuel pressure in a reservoir. This way, individual injectors add smaller amounts of fuel as mechanically or electronically defined by CDI's technology. That pressure stays the same, even when fuel injectors are in "stand-by" mode. This produces balanced, or "square," injection patterns that stabilize fuel supply and efficiency.
Cleaner Air
In a Clean Air Task Force report, Dr. L. Bruce Hill contends that reducing "black carbon," the black particulate smoke that is emitted by diesel engines, would more quickly impact world temperature patterns than an equivalent reduction in carbon dioxide. U.S. Class 8 trucks (those exceeding 33,000 pounds, such as tractor-trailers, waste haulers and large buses) contribute significantly to U.S. diesel pollution, according to Dr. Hill. However, technology is readily available to bring black carbon emissions under control. Common-Rail Direct Injection engines reduce particulate emissions by 60 percent, according to Autozine. If so, truck fleets could reduce their environmental impact by retrofitting with the CDI fuel injection systems that have taken hold in Compact Recreational Vehicles.
Tags: fuel injection, Common Rail, Common Rail Injection, engine cylinder, Injection systems, Rail Injection, Rail Injection systems
