2.5.3. Diesel 5-cylinder engines: Е 250 D and E 290 TD
Diesel 5-cylinder engines E 250 D (in domestic market of OHMS 605) with a volume of 2,5 l technically correspond, despite various number of cylinders, to the known 4-cylinder engine E 220 D (OHM 604). Krivoshipno-shatunnaya the group is mounted on 6 bearings at the 5-cylinder engine (by analogy with 5 bearings at the 4-cylinder engine). Instead of distributive FPHP (fuel pump of high pressure) is installed line TNVD with electronic control. Besides, models with a mechanical box of gear shifting have a 2-mass flywheel for improvement of smoothness of the course.
Fig. 1.11. Turbodiesel of 2,9 l (view from the party of a flywheel). Here the flywheel, a turbocompressor of the fulfilled gases and elements of system of production of the fulfilled gases are visible
Other model of the 5-cylinder engine — E 290 TD (in domestic market of OHMS 602) with a volume of 2,9 l (fig. 1.11 and 1.12) is the first model of the diesel with direct injection for the Mercedes-Benz car.
The diesel has 2 valves on the combustion chamber. The nozzle is directly screwed in it. In usual forkamerny system fuel "is, if I may say so, stored" in the precamera before self-igniting directly in the combustion chamber. The system of direct injection differs from forkamerny in essential reduction of fuel consumption. It is provided due to more effective combustion of fuel as it under high pressure (to 31 MPa) gets directly to the combustion chamber where at once ignites under the influence of hot compressed air of high pressure.
At the engine E 290 TD (OHMS 602) air is condensed previously with a turbocompressor of the fulfilled gases (similarly to KKK or Garrett), accelerates and moves in the vortex camera of a head of cylinders.
Fig. 1.13. A turbodiesel of 2,9 l with direct injection, a turbocompressor of the fulfilled gases and a radiator of nadduvochny air
The radiator of nadduvochny air (fig. 1.13) located before a cooling system radiator which brings temperature of the soaked-up air to 80 °C thereby is in addition used increasing density of the air given to the combustion chamber.
The compact turbocompressor is adjusted in such a way that reaches the maximum absolute pressure of 195 kPa with a frequency of rotation of a bent shaft of the mines-1 engine 1900. At turbo engines of the previous models at a start of motion of the car or sharp pressing the accelerator pedal it was formed "turboprovat" – a lack of the arriving air. At the engine E 290 TD (OHMS 602) the compressor is adjusted so effectively that this shortcoming is practically not felt.
Management of the beginning and number of injection is carried out by the EDS system (Elektronic Diesel Control) having about 50 set parameters. Numerous sensors of a condition of the engine monitor change of parameters at the movement and issue indications in the form of electric signals on EDC which in turn issues the command of management for quantity and an order of injection.
EDC operates both start of the motor, and speed of idling and amount of the fulfilled gases which are taken away on reburning. Control is exercised by the principle of just enough – EDC gives so much fuel how many it is necessary for optimum operation of the engine to combustion chambers.
In June, 1999 the new line 5-cylinder diesel engine E 270 CDI replaced model E 290 TD. The engine E 270 CDI (fig. 1.14) became a combination of optimum characteristics.
Power of the diesel engine E 270 CDI increased by 31,5% in comparison with the previous model and reached 125 kW / 170 h.p. with a frequency of rotation of a bent shaft of the mines-1 engine 4200, and in the range of frequencies of 1600-2400 min.-1 the torque increased to 370 N · m. The maximum speed of the car made 225 km/h, and average fuel consumption (NEFZ) – 6,9 l on 100 km.