Fig. 1.11. 2.9L turbodiesel (view from the flywheel side). The flywheel, exhaust turbocharger and exhaust system components are visible here
Fig. 1.12. 2.9L turbodiesel (view from the suction side)
Another 5-cylinder engine model is the E 290 TD (on the domestic market OM 602) with a volume of 2.9 l (fig. 1.11 and 1.12) is the first direct injection diesel engine for a Mercedes-Benz passenger car.
Diesel has 2 valves per combustion chamber. The injector is screwed directly into it. In a conventional pre-chamber system, the fuel is, so to speak, "stored" in the pre-chamber before spontaneously igniting directly in the combustion chamber. The direct injection system differs from the pre-chamber system by a significant reduction in fuel consumption. This is achieved by more efficient combustion of the fuel, since it enters the combustion chamber under high pressure (up to 31 MPa), where it immediately ignites under the action of hot, high-pressure compressed air.
In the E 290 TD (OM 602) engine, the air is pre-compressed by the exhaust gas turbocharger (similar to KKK or Garrett), accelerates and is fed into the swirl chamber of the cylinder head.
Fig. 1.13. 2.9L turbodiesel with direct injection, exhaust gas turbocharger and charge air cooler
Additionally, a supercharged air radiator (Fig. 1.13) is used, located in front of the cooling system radiator, which brings the temperature of the intake air to 80°C, thereby increasing the density of the air supplied to the combustion chamber.
The compact turbocharger is adjusted in such a way that it reaches a maximum absolute pressure of 195 kPa at an engine crankshaft speed of 1900 min⁻¹. In previous models of turbo engines, when the car starts moving or when the gas pedal is pressed sharply, a "turbo dip" occurs - a lack of incoming air. In the E 290 TD (OM 602) engine, the compressor is adjusted so effectively that this deficiency is practically not felt.
The start and quantity of injection are controlled by the EDS system (Elektronic Diesel Control), which has about 50 preset parameters. Numerous engine condition sensors monitor changes in parameters during movement and provide readings in the form of electrical signals to the EDC, which in turn issues a control command for the amount and order of injection.
EDC controls both engine start and idle speed and the amount of exhaust gases diverted for afterburning. Control is based on the just enough principle – EDC supplies the combustion chambers with as much fuel as is necessary for optimal engine operation.
Fig. 1.14. Diesel 5-cylinder engine E 270 CDI
In June 1999, the new in-line 5-cylinder diesel engine E 270 CDI replaced the E 290 TD model. The E 270 CDI engine (Fig. 1.14) was a combination of optimum characteristics.
The output of the diesel engine in the E 270 CDI has increased by 31.5% compared to the previous model and now reaches 125 kW/170 hp at an engine speed of 4,200 min - 1, and the torque has increased to 370 Nm in the speed range of 1,600–2,400 min - 1. The vehicle's top speed is 225 km/h, and the average fuel consumption (NEFZ) is 6.9 l per 100 km.