Introduction to Pollutant Emission
Diesel is obtained by the fractional distillation of petroleum and is formed by a variety of hydrocarbons with a boiling point ranging from 180°C to 360°C (Standard DIN 51 601 applied in Germany). The composition of Diesel after distillation will vary according to the quality of the Petroleum. used. the amount of sulfur and other undesirable compounds must be treated and monitored by the manufacturer. The ideal theoretical diesel air/fuel ratio is 14.5 parts air to 1 part diesel. During engine operation, the air/fuel mixture is extremely lean, with Lambda ranging from 1.1 to 1.4.
This system makes it possible to carry out a pre-injection (pilot) before the PMS, with the advantage of control the pressure rise inside the chamber, making the motor quieter, which is a characteristic of “Common Rail” engines. The electronic control unit controls the amount of fuel injected, regulating the pressure in the tubing and injection duration.
The information that the plant uses to control the amount of fuel to be injected are:
- Engine rotation.
- Overfeed pressure.
- Air temperature.
- Amount of air drawn in.
- Battery voltage.
- Fuel pressure.
- Position of the accelerator pedal.
Electronic injection advance control
The advance, moment of injection start, expressed in degrees, can be different from injection to injection, and also from cylinder to cylinder, is calculated similarly to dosage of fuel by injection and according to the engine load (position of the throttle, engine speeds and inlet air).
engine start
In the first rotations, during start-up, the phase and voltage signals are synchronized. recognition of cylinder number 1 (flywheel sensor and camshaft sensor). At start-up, the accelerator pedal sensor signal is ignored. the dosage of injection is determined, exclusively, through the water temperature, through a map in the central program. When the control unit identifies that the motor is already rotating at a speed higher than the starting speed (drag with the starter motor), the accelerator pedal is re-enabled.
cold start
If one (only one) of the temperature sensors (water, air or fuel) indicates a temperature below 10oC, the cold start system is activated. When the ignition switch is turned on, the cold start indicator light on the dashboard lights up, and it remains so for a period that varies according to the temperature (until the candle heater at the inlet to the intake manifold to heat the air). Then the light starts flashing. At this point, the engine can be started. With the engine running, the dashboard light goes out, however, the glow plug will remain on for a while, performing post-heating. If during the period when the indicator light is flashing intermittently, and the engine is not started within 20 to 25 seconds, the system will be deactivated so as not to drain the batteries.