Basic Function Of Injection Valve - GF07.03-P-2001A

Engine 139, 176, 177, 254, 256, 260, 264, 274, 279, 282 

Engine 177, 256 

Example illustration of 6-cylinder spark-ignition engine (direct injection) 

Overview 

This document contains information on:

• General 
• Function 
  • Fuel injection 
  • Injection valves with multi-hole nozzles 

General 

The injection valves (1.1 - 1.6) inject the fuel into the respective cylinder (direct injection) and/or into the intake manifold (intake manifold injection).

The respectively injected fuel quantity depends on the actuation duration of the corresponding injection valve (1.1 - 1.6).

The injection quantity is determined by additional factors:

• Opening and closing speed of nozzle needle.
• Needle lift height.
• Nozzle geometry.
• Fuel distributor pressure.

Function 

Fuel injection 

The injection valves (1.1 - 1.6) switch extremely quickly and can also inject the smallest of fuel quantities.

Due to the high fuel pressure of approx. 130 to 250 bar, the outward opening nozzle produces a stable hollow-cone jet under all operating conditions, this is a basic requirement for an interruption-free stratified charge operation. The combustion engine control unit generates the control voltage of 140 to 210 V for the fuel injectors and actuates the fuel injectors with a ground signal. The stroke of the nozzle needle is, in this connection, approx. 35 μm. The piezo actuator module represents a capacitative load for the combustion engine control unit.

When opening, a current of approx. 8 A flows for a few milliseconds. The combustion engine control unit reverses the polarity for opening and closing. The short switching times of the piezo injectors facilitate a multiple injection with short breaks during a combustion cycle.

Injection valves with multi-hole nozzles 

Multi-hole injection valves are very similar to conventional fuel injectors (diesel engine) in terms of their design. The multi-hole nozzle enables very flexible types of jets, as the number and location of the injection jets can be adapted to the combustion chamber and the requirements of the combustion system. For example, an asymmetrical spray contour allows emission-critical areas in the combustion chamber to be left out in a targeted way, thereby preventing the open intake valves from being wetted during the injection as part of the intake stroke. A gap in the spray can also prevent the spark plug from being wetted with fuel. The injection orifices can vary depending on the insert. Variants usually have between 4 and 12 injection orifices. There is also the possibility of tilting the injection jets opposite the axis of the injection valves (1.1 - 1.6), which further increases the flexibility of the installation. Due to the design, there is always a dead volume between the valve seat and the injection orifice outlet. After the float needle is closed, the fuel that remains here evaporates into the combustion chamber. The residual fuel can cause carbonization on the nozzle, which may affect the distribution of the jet. The geometric design of the injection orifices can influence the spray distribution and mixture formation.

Injection valves with multi-hole nozzles are commonly used for direct injection.

Injection valves with C-nozzles are normally used for intake manifold injection.

	Component descriptions
	Injection valve, component description	Model 223	GF07.03-P-6121A
		Model 232	GF07.03-P-6121F
		Model 254	GF07.03-P-6121H
		Model 214	GF07.03-P-6121K
		Model 118 as of model year 2023 Model 177, 247 as of model year 2022	GF07.03-P-6121L
		Model 167 as of model year 2023	GF07.03-P-6121M
		Model 192	GF07.03-P-6121R
		Model 236	GF07.03-P-6121S