FUEL INJECTOR [SKYACTIV-D 1.8]
id0114q9108200
Purpose, Function
• The fuel injectors inject fuel in the cylinder over a wide area, intake air and fuel are mixed efficiently, and the optimum air-fuel mix are formulated according to the driving conditions.
Construction
• The fuel injectors are located on the cylinder heads.
• Multi-hole piezoelectric type injectors have been adopted for the fuel injectors.
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Note
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• The fuel injector has a built-in fuel pressure sensor/fuel temperature sensor.
Operation
• The fuel injectors inject fuel according to the signal from the PCM. The fuel injection time is determined by the energization time to the piezoelectric element.
Fuel injection mechanism
1. Before fuel injection (while fuel injection is stopped)
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• Because the three-way valve is pressed up when there is no energization to the piezoelectric element, the passage flowing fuel from the intermediate chamber is closed. Because the pressurized fuel fills the control chamber and pressure for pressing down the nozzle needle is applied, fuel injection is not performed.
2. Fuel injection starts (nozzle needle rises)
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• When energization to the piezoelectric element starts, the three-way valve is pressed down and fuel in the control chamber passes through the control plate and flows out. When the fuel flows out, the pressure in the control chamber decreases, the nozzle needle is pressed up, and fuel injection is started.
3. Fuel injection stops (nozzle needle lowering start)
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• When energization to the piezoelectric element stops, the three-way valve is pressed up and the high pressure fuel flows into the intermediate chamber from the orifice (sub). When the high pressure fuel flows in, the pressure in the intermediate chamber increases and the control plate is pressed down.
4. Fuel injection stops (nozzle needle lowers)
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• The nozzle needle is closed instantaneously by increasing the pressure in the control chamber and the fuel injection is stopped.
