The new M 282 petrol engine: four-cylinder with cylinder shutoff
The new entry-level engine in the A 200 is the M 282 with a displacement of 1.33 litres. Compared to the previous 1.6-litre engine, the output of this all-aluminium engine has increased by up to eleven percent and the output per litre by no less than 25 percent. This engine excels with very compact dimensions, low weight and high static and dynamic rigidity. The turbocharger features an electronically controlled wastegate: thanks to flexible charge pressure control, it is also possible to set an optimum charge pressure under partial-load conditions.
This is the first four-cylinder Mercedes-Benz engine to feature cylinder shutoff (initially in conjunction with the 7G-DCT transmission). In the partial load range between 1250 and 3800 rpm, and depending on the power requirement, the intake and exhaust valves of the second and third cylinder are closed by valve clearance adjustment. The remaining two cylinders therefore operate under higher loads, and more efficiently. To minimise friction, the cylinder walls are coated using the patented NANOSLIDE® process. The piston skirts are given an Eco-Tough coating, a special graphite coating for optimised friction and high wear resistance.
Another special technical feature is the delta cylinder head, so called because of its shape. It is slightly higher when installed, but much narrower and lighter than conventional cylinder heads. Further advantages include the semi-integrated intake and exhaust manifolds, which allow compact construction. Daimler holds a patent for the compact arrangement of the high-pressure injection pump with a maximum of 250 bar. The multi-hole injection nozzles are centrally located in the combustion chamber, and injection occurs without the valves being subjected to the jet of fuel.
This new, high-compression four-cylinder engine has a particulate filter as standard. Particular effort was also devoted to noise emissions. The intake air duct features a Helmholtz resonator, the catalytic converter has insulating seals and the cover also has a noise-reducing role.
The new engine will initially be available with the 7G-DCT dual clutch transmission, and later also with a six-speed manual transmission and 4MATIC all-wheel drive.
The M 282 was developed by Mercedes-Benz in cooperation with Renault. It is produced at the Kölleda plant in Thuringia, Germany and in future it will also be produced in Beijing, China. Renault supplies the components of the long block engine.
The new M 260 petrol engine: premiere of CONICSHAPE®
The M 260 four-cylinder engine of the A 250 is essentially a further development of the previous M 270, with an output increase of over 6 percent compared to its predecessor. Its engine block of diecast aluminium with cast iron cylinder liners conceals a world premiere in large-scale production: CONICSHAPE®, also known in-house as "trumpet-honing". To further minimise piston friction and lower fuel consumption, the cylinder bore is widened at the lower end of the cylinder liners. The resulting, conical shape resembles the mouth of a trumpet. An innovative low-friction oil and optimised piston rings also reduce friction losses. To take account of the higher specific output, the pistons themselves feature cooling ducts. This also ensures more efficient combustion. The balance shafts for smooth engine-running are located in the lower section of the crankcase.
Also new in the aluminium four-valve cylinder head of the two-litre engine is CAMTRONIC, a variable valve timing system that allows two-stage adjustment of the valve lift on the intake side of the valve assembly. In the partial-load range, this variable valve lift adjustment allows less air to be fed to the combustion chamber with a smaller valve lift, which leads to lower gas cycle losses. In higher load ranges the system switches to the higher valve lift to achieve the engine's full power delivery.
Multiple fuel injection ensures optimum combustion despite the smaller valve lift. This compensates the reduced turbulence of the fuel/air mixture in the combustion chamber in the area of the spark plug. The four-cylinder has direct injection with latest-generation piezo injection valves. The position of the injectors has been optimised to achieve low cylinder wall coverage and therefore lower untreated emissions, especially particulate emissions. A particulate filter is included as standard. Thanks to optimised injection with partial valve lift, the engine runs even more quietly in wide operating ranges. A low level of exhaust emissions has been achieved by further development of the well-proven BlueDIRECT combustion system in conjunction with the standard petrol particulate filter.
The single-pipe turbocharger features an electronically controlled wastegate valve. The previously vacuum-operated actuator has been replaced by a precision electrical actuator, which reports its position and has a higher actuating speed, so that charge pressure control and diagnosis are significantly improved. This allows charging to be more precisely controlled.
The oil circuit is supplied with engine oil on a demand basis. Sensors monitor the oil pressure so that the supply volume can be adjusted. The cooling circuit has an electronically controlled thermostat which allows the engine temperature to be optimally set to suit needs.
To make engine operation more comfortable, a new centrifugal damper has been introduced into the powertrain as an addition to the balance shafts. This improves the engines NVH characteristics and allows comfortable driving possible at lower rpm. The exhaust system with flap control has the same purpose.
The engine is configured for front-wheel drive and 4MATIC all-wheel drive, and combined with the 7G-DCT dual clutch transmission. The M 260 engine is produced by the Kölleda plant.
The new OM 608 diesel engine: quieter and cleaner
The entry-level OM 608 diesel engine in the A 180 d is a new development based on the OM 607. It is more powerful (85 kW, 5 kW more), has further reduced emissions, complies with EU 6d temp including the new requirements relating to Real Driving Emissions – RDE, and has optimised noise characteristics.
New technological components include the improved turbocharger with variable turbine geometry integrated into the exhaust manifold. An electric actuator now adjusts the turbine geometry Together this makes for a more immediate charging response. The intake air is now cooled by an engine-mounted water intercooler.
The installed height of the new aluminium cylinder head has been reduced, and the moving masses of the valve assembly reduced. The intake manifold is now integrated into the cylinder head cover. The pressure of the common-rail injection system has been increased to 2000 bar (previously: 1600 bar). The electro-magnetically controlled injectors have eight injection holes. This allows precise combustion control by up to six injections per working cycle. Dual pre-injection is used to optimise combustion noise in wide operating ranges, and the injectors are sealed in their shafts.
The cast-iron engine block has been made lighter, while increasing its rigidity. Weight-optimised steel pistons are used as before. A demand-controlled oil pump is used, with a pressure regulating valve adjusting the oil pressure on the basis of need and temperature-dependent characteristics maps.
For sound insulation, the sump has a polyurethane foam cover, the engine cover an interior foam lining and the design cover an interior PET lining.
For low emissions, the OM 608 is equipped with high and low-pressure exhaust gas recirculation. The compact exhaust aftertreatment system is near-engine mounted. Alongside the oxidation catalytic converter and the particulate filter, SCR catalytic converters with AdBlue® metering are used for the first time in this engine class. The particulate filter also has an SCR coating. A large AdBlue® tank with a capacity of 23.8 litres ensures long refilling intervals, and has its own, externally accessible filler neck next to the diesel filler neck.
At market launch the engine is available with a new 7G-DCT dual clutch transmission. The OM 608 was developed as part of a strategic cooperation with Renault. The Mercedes-Benz specific technology components include: