Volkswagen Ag

Bernd Stiebels

Ekkehard Pott

Leo Spiegel

Eduard Lippert

Michael Lindlau

Rudolf Krebs

Oliver Fladung

J&ouml;rg Theobald

Marc Schweizer

A direct injection internal combustion engine, especially an Otto engine, is provided with layered lean operation and internal exhaust-gas recirculation. An exhaust-gas aftertreatment for reducing Nox using an Nox storage catalyst is also provided. This combination is to achieve the highest possible exhaust-gas recirculation rates with the lowest HC and Nox emission values. A tumble flow is provided for the incoming fresh gases, which may contain recirculated exhaust gas from external exhaust-gas recirculation. The swirl axis of the incoming fresh gases therefore extends substantially crosswise to the piston movement. This results in an emissions-reducing, optimal mixture inside the cylinder during the layered lean operation.

Direct injection internal combustion engine with NOx-reduced emissions

A method for operating an internal combustion engine with at least one working piston with a variable compression ratio, which can be changed as a function of an operating state of the internal combustion engine, the method including the steps of: detecting, with a knock sensor, when the compression ratio is too high; reducing the compression ratio (V) when the knock limit (L) is at least reached by a first, predetermined value (V ), which is a function of the operating state, over a first, predetermined time period (t -t ); subsequently increasing the compression ratio (V) by a second, predetermined value (V ) over a second, predetermined time period (t -t ) until the knock limit (L) is at least reached again; and determining at least one of the first predetermined value (V ), the first time period (t -t ), the second predetermined value (V ), and the second time period (t -t ) as a function of load demand on the internal combustion engine.

Method for operating an internal combustion engine comprising at least one working piston

The invention relates to a four stroke internal combustion engine with applied ignition, wherein fuel is directly injected into a combustion chamber by means of an injector. Said engine comprises at least one admission channel with an admission valve and at least one exhaust channel with an exhaust valve, the admission valve and the exhaust valve being placed on opposite sides of the combustion chamber and the injector being placed on the admission valve side. Said engine also comprises a cavity formed in a piston top. A piston exhibits a central longitudinal axis extending in the direction of displacement of said piston. The cavity is placed on the admission valve side and exhibits, relatively to said admission valve and the injector, a marginal area forming the highest point of the piston top so that an airflow originating in the appropriately designed admission channel and penetrating into the combustion chamber through the admission valve and an injection jet originating in the injector and penetrating into the combustion chamber enter the cavity at opposite points.

Four-stroke internal combustion engine with direct injection

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Adenbuttel, Germany

Bernd Stiebels