Fuel Injector - Technical Description (Edit)
Oct 20, 2006, 06:30 AM
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Fuel Injector - Technical Description (Edit)
I'm not sure where else to post this. I had to create a description of a fuel injector (for school). Just wondering if any information could be added.
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A standard automotive fuel injector is roughly 3 inches long and ½ inch wide. The injector is basically an electronically controlled valve, capable of being opened and closed once every 6 milliseconds. The injectors outer appearance consists of the upper o-ring that seals the top of the injector to the fuel rail (bottom right), and a lower o-ring that seals the bottom of the injector to the intake manifold (top left). The pintle cap is located below the lower o-ring, it functions to insulate the injector from the heat of the intake manifold, and it also acts as a support for the lower o-ring. An electrical connector is also present on the injector body.
In an operating cycle, the injector which is seated in the fuel rail has a constant supply of pressurized fuel, originating from the fuel tank, ending up inside the fuel rail where the injector is seated. Fuel is then forced into the injector fuel feed recess. Fuel then migrates down toward a small filter element inside the injector where the fuel is rid of any micro-particles that would inhibit proper atomization. After filtering, the fuel travels through the injector body awaiting the electronically controlled valve inside the injector fuel chamber to open, allowing fuel to flow past, and into the pintle. The pintle is a finely machined part, approximately ¼ inch in diameter with up to 6 evenly spaced pin holes designed to ensure fuel is injected into the engine in a uniform spray, also aiding in fuel atomization. Under pressure the fuel flows through the pintle and exits the injector through the spray tip. Atomized fuel then travels through the engines intake ports, and into the combustion chamber. That sums up ONE injector cycle, this process is undergone several times per second.
The fuel injector can inject fuel extremely precisely. It is a computer controlled device, the computer determines the amount of fuel to inject by receiving information from sensors that give information about the engines current operating conditions. The onboard computer makes fuel calculations according injectors flow rating. The injectors flow rating is determined when a given constant base fuel pressure is given, and the injector valve is fully opened. Fuel output is then measured for one minute. Most automotive fuel injectors are rated at 250cc/min – 600cc/min. Since pressure inside the fuel rail is constant, fuel metering is solely a function of injector open time. A value for injector open time is measured in milliseconds, and varies across the engines RPM (revolutions per minute), and load ranges (MAP(manifold absolute pressure)).
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ANY input would be helpful.
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A standard automotive fuel injector is roughly 3 inches long and ½ inch wide. The injector is basically an electronically controlled valve, capable of being opened and closed once every 6 milliseconds. The injectors outer appearance consists of the upper o-ring that seals the top of the injector to the fuel rail (bottom right), and a lower o-ring that seals the bottom of the injector to the intake manifold (top left). The pintle cap is located below the lower o-ring, it functions to insulate the injector from the heat of the intake manifold, and it also acts as a support for the lower o-ring. An electrical connector is also present on the injector body.
In an operating cycle, the injector which is seated in the fuel rail has a constant supply of pressurized fuel, originating from the fuel tank, ending up inside the fuel rail where the injector is seated. Fuel is then forced into the injector fuel feed recess. Fuel then migrates down toward a small filter element inside the injector where the fuel is rid of any micro-particles that would inhibit proper atomization. After filtering, the fuel travels through the injector body awaiting the electronically controlled valve inside the injector fuel chamber to open, allowing fuel to flow past, and into the pintle. The pintle is a finely machined part, approximately ¼ inch in diameter with up to 6 evenly spaced pin holes designed to ensure fuel is injected into the engine in a uniform spray, also aiding in fuel atomization. Under pressure the fuel flows through the pintle and exits the injector through the spray tip. Atomized fuel then travels through the engines intake ports, and into the combustion chamber. That sums up ONE injector cycle, this process is undergone several times per second.
The fuel injector can inject fuel extremely precisely. It is a computer controlled device, the computer determines the amount of fuel to inject by receiving information from sensors that give information about the engines current operating conditions. The onboard computer makes fuel calculations according injectors flow rating. The injectors flow rating is determined when a given constant base fuel pressure is given, and the injector valve is fully opened. Fuel output is then measured for one minute. Most automotive fuel injectors are rated at 250cc/min – 600cc/min. Since pressure inside the fuel rail is constant, fuel metering is solely a function of injector open time. A value for injector open time is measured in milliseconds, and varies across the engines RPM (revolutions per minute), and load ranges (MAP(manifold absolute pressure)).
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ANY input would be helpful.
