FUEL INJECTOR [SKYACTIV-D 2.2]

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Purpose, Function

Construction

Fuel injector (2pin type)

•  The fuel injectors are installed to the engine compartment.

•  The fuel injectors consist of a Piezo-electric element, a displacement magnification unit, control valve, and nozzle needle. In addition, there are a number of injection holes on the tip of the injector.

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Piezo-electric element

―  The element possesses a property which generates voltage when a load (displacement) is applied, and load (displacement) when voltage is applied.

Displacement magnification unit

―  Consisting of the sliding part (large-diameter piston, small-diameter piston) and the oil seal chamber, it magnifies the displacement of the Piezo-electric element and transmits it to the control valve.

Control valve

―  It opens/closes the upper seat and lower seat by the displacement of the Piezo-electric element, and controls the back pressure on the nozzle needle.

Nozzle needle

―  Injects fuel by moving up and down based on the opening/closing of the control valve.

Fuel injector (6pin type)

•  The fuel injectors are installed to the cylinder heads.

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•  Multi-hole piezoelectric type injectors have been adopted for the fuel injectors.

Note

•  The fuel injector has a built-in fuel pressure sensor/fuel temperature sensor.

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Fuel pressure sensor/fuel temperature sensor

•  Further precise fuel injection amount correction can be performed by a built-in fuel pressure sensor/fuel temperature sensor to improve fuel injection accuracy.

Piezoelectric element

•  The element possesses a property which generates voltage when a load (displacement) is applied, and load (displacement) when voltage is applied.

Operation

Fuel injector (2pin type)

•  Injects fuel according to the signal from the PCM. The fuel injection time is determined by the energization time of the coil.

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Fuel injection mechanism

1.  Applies electric charge to the Piezo-electric element, and utilizes the property of the Piezo-electric element to cause it to expand.

2.  The amount that the Piezo-electric element expands is magnified by the displacement magnification unit.

3.  The control valve is driven by the magnified expansion amount, causing the upper seat to open and the lower seat to close, which lowers the pressure in the nozzle back pressure chamber.

4.  Based on the lowering of the pressure, the fuel injection initiates by the upward movement of the nozzle.

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Fuel injector (6pin type)

•  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.

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Fuel injection mechanism

1.  Before fuel injection (while fuel injection is stopped)

―  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)

―  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)

―  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 up.

4.  Fuel injection stops (nozzle needle lowers)

―  The nozzle needle is closed instantaneously by increasing the pressure in the control chamber and the fuel injection is stopped.

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Fail-safe

DTC	Fail-safe
P0201:00 P0202:00 P0203:00 P0204:00 P1378:00 P1379:00 P2146:00 P2147:00 P2148:00 P2149:00 P2150:00 P2151:00	•  PCM restricts engine torque. •  Inhibits the EGR control. •  Inhibits the diesel particulate filter regeneration control. •  Inhibits engine-stop by operating the i-stop function. •  PCM restricts engine-transaxle integration control.
P1675:00 P1676:00	•  Limits the engine torque or the upper limit of the engine speed. •  Inhibits the auto DPF regeneration control. •  Fully open the intake shutter valve. •  Inhibits the compulsory DPF regeneration control. •  Inhibits the EGR control. •  PCM restricts engine-transaxle integration control. (ATX) •  Inhibits engine-stop by operating the i-stop function.