Information on the 4 Cylinder Gasoline Engine M 271 EVO | Mercedes-Benz

Brief description: M 271 EVO From September 2009 the M 271 EVO will be used in the BlueEFFICIENCY models of the C-Class and E-Class. There are three power variants: 115, 135 and 150 kW. The development of the M 271 EVO combines the following objectives: • Improved responsiveness due to increased power and higher torque • Improved comfort thanks to smoother running • Significantly lower fuel consumption and reduced CO2 emissions • Compliance with the Euro 5 standard The M 271 EVO therefore combines the BlueEFFICIENCY requirements for economy and environmental compatibility with comfort and driving pleasure. These objectives are realized by a variety of technical innovations and improvements: • Low-noise and low-maintenance chain drive • Camshaft adjustment • Lanchester balancer • Homogeneous direct injection with 140 bar injection pressure • Fuel injectors • Quantity-controlled fuel pump • Turbocharger • Lambda control • Secondary air injection for rapid heating of the catalytic converter • Two-disk thermostat with three-disk functionality • Radiator shutters • Regulated oil pump with high efficiency • Ignition system • ECO start/ stop system Overview of new features and improvements 1 Exhaust system with turbocharger, optimized lambda control and secondary air injection 2 Ignition system 3 Homogeneous direct injection with quantity-controlled fuel pump 4 Fuel injectors 5 ECO start / stop system 6 Regulated oil pump 7 Lanchester balancer 8 Radiator shutters 9 Two-disk thermostat with three-disk functionality 10 Low-noise and low-maintenance chain drive with optimized camshaft adjustment Cylinder head: The cylinder head and the intake valves have been adapted to cope with the demands of homogeneous direct injection. The M 271 EVO operates according to the four-valve concept with two camshafts, two camshaft adjusters and central spark plugs. Camshaft adjuster The camshaft adjusters of the forged intake and exhaust camshafts are vane-cell adjusters and have been further improved. They allow the timing to be varied steplessly and more quickly than before. The camshaft adjuster is a hydraulic swivel drive. The adjustment angle is 40° (crank angle) – corresponding to an angle of 20° performed at the adjuster (exhaust). The adjustment of the camshafts optimizes the engine torque curve and improves exhaust charac- teristics. A spring-loaded pin locks the camshaft adjuster in the basic position when the engine is switched off in order to prevent uncontrolled movement of the adjuster during start-up. The new camshaft adjuster is 34% lighter while the rate of adjustment is twice as fast. Crankcase Crankcase ventilation The M 271 EVO features two crankcase ventilation systems: • Partial load ventilation with single cyclone oil separator • Full load ventilation with double cyclone oil separator Partial load ventilation The single cyclone oil separator is responsible for separating the oil at the partial load ventilation line. The partial load ventilation line runs from the left engine support flange into the charge air distribution line downstream of the throttle valve actuator. Via an opening in the crankcase the blow-by gas (blow- by quantity) flows into the single cyclone separator which is located behind the left engine support. The oil separator is in the form of a cyclone: Incoming air is made to spiral and the resulting centrifugal forces separate the oil, which flows back into the housing. The air cleaned in this way leaves the oil separator through a combination valve installed above the cyclone, which acts as a check valve in the event of overpressure in the charge air distribution line and as an air shutoff valve to protect the catalytic converter.