The success story of the innovative SD oil separator from MANN+HUMMEL continues. The product now finds application in a highly integrated module for crankcase ventilation with Mercedes-Benz.

In combustion engines gases are generated during combustion which, for example, can be pressed past the piston rings into the crankcase. The oil particles contained in this blowby can deposit themselves on the turbocharger, the intercooler and the inlet valves and as a result cause damage. The separation of oil droplets from the blowby returned to the intake air is therefore important and also relevant for the reduction of oil consumption. Effective oil separation is a condition to meet the emission standards of modern engines and is also necessary for the protection of the components of the intake system.

Clever design

The SD oil separator (structured deflection) which MANN+HUMMEL presented in 2013 was and remains pioneering in terms of efficiency and its compact design. In 2015 the product went into series for the first time with an Indian car manufacturer. Since then the solution has established itself on the market. Now the component will also find application in a 2.0 liter 4-cylinder gasoline engine from Mercedes-Benz, mounted longitudinally for models with rear wheel drive and transversely for vehicles with front wheel drive. The ambitious aim of the customer here was to achieve a considerably greater oil separation in a smaller installation space with less interfaces.

Firstly coarse, then fine

The blowby which escapes from the crankcase contains oil particles with varied sizes. It includes visible droplets as well as droplets which are substantially smaller than one micrometer. The challenge here is to separate all the sizes with a high level of efficiency. The MANN+HUMMEL experts solved this task by fitting the pressure control valve with the SD oil separator on the crankcase such that the cylinder head is closed by the component like a cover. This type of mounting creates a settling chamber between the cylinder head and SD fine separator where the blowby loses kinetic energy. Consequently, large and heavy oil particles are released from the gas and can be efficiently separated. The settling chamber becomes a coarse separator. In the follow-up this pre-cleaned blowby is directed through a number of nozzles bores in the SD oil separator. The narrowing of the cross section in this process causes the gas to accelerate again and it impacts the deflector plate with a high amount of kinetic energy. There the air/oil mix is radically deflected by the special pyramid-shaped structure of the plate which causes even the smallest particles to coalesce, i.e. to come together to form an oil film, which then flows back to the oil circuit. The pyramid structure of the SD deflector plate significantly increases the efficiency of the oil separator.

Robust, reliable and variable

Also this new variant of the oil separator from MANN+HUMMEL convinces with its robust component concept which can find application in very small installation spaces. According to the California Air Resources Board (CARB), crankcase ventilation is relevant for exhaust emissions. The laser-welded pressure control valve cannot be opened without damage and therefore meets the requirements of the OBD II on-board diagnostics standard. Numerous control and safety valves ensure that the crankcase ventilation works perfectly in all situations. Two non-return valves, one for the full-load and one for the part-load ventilation, ensure that the cleaned air reaches the fresh air path against the prevailing pressure gradient. A ball-type non-return oil valve prevents the bypass of blowby and the drawing in of oil from the sump. If it is technically necessary the oil separator can, however, be bypassed using a bypass valve.

The new crankcase ventilation system for Mercedes-Benz is the latest series product of the MANN+HUMMEL SD oil separator family. MANN+HUMMEL experts are currently working on approximately ten development projects for oil separation with international car manufacturers. As a result, many new products will enter series production in the coming months and years.