Injector
Injector
Injector
The injector sprays the fuel into the combustion chamber under high pressure. The injector opens the tip of the nozzle needle outwards and forms a ring gap that is only a few micrometers wide. The ring gap shapes the high precision injection and ensures even, cone-shaped divergence. The piezo-electric activation has the following advantages compared to activation via solenoid coils:
- improved possibilities for multiple fuel injection due to rapid switching times with very short response times
This results in significant improvements with regard to pollutant emission as well as fuel consumption.
Functional description
The outwards-opening injector enables high precision injection. Only this makes it possible to keep the injected fuel cone stable, also under the prevailing influences of pressure and temperature in the combustion chamber. This injector enables injection pressures of up to 200 bar and extremely fast opening of the nozzle needle. This means it is possible to inject fuel into the combustion chamber, regardless of the operation cycles that are restricted by the valve opening times.
The fuel quantity required for the operating situation is injected by the injector in the combustion chamber. This volume can be influenced with three control variables:
- Rail pressure
- Opening period of injector
- Opening stroke of injector
The nozzle opening period and opening stroke are specified by the engine control. The nozzle opening period is controlled via the fuel injection signal (Ti signal). The opening stroke is controlled via the energy quantity used for activation of the injector.
Structure and inner electrical connection
A piezo element is an electromechanical converter. The piezo element is a type of ceramic that converts electrical energy directly into mechanical energy (power/travel). The piezo element expands when voltage is applied. This creates the stroke of the nozzle needle. To achieve a greater stroke, a piezo element can be structured in a number of layers.
Activation and setpoint values
Vehicle voltage is supplied to the engine control. The engine control contains a DC/DC converter that steps up the voltage required for activation of the injector. The injector is activated by the engine control on the ground side.
Observe the following setpoint values for the injector:
Size Value
Maximum supply voltage 190 Volts
System pressure 5 to 20 MPa
Opening period, closing period 100 to 200 micro s
Dynamic flow at 0.4 ms 14.5 mg/stroke
Temperature range -30 °C to 140 °C
Diagnosis instructions
Failure of the component
If an injector fails, the following behavior is to be expected:
- Fault entry in the engine control unit
- Cylinder cutout
- The emissions warning light lights up in the instrument panel
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.