DE19930086B4 - Method for operating an internal combustion engine - Google Patents

Abstract

An internal combustion engine (1) is described, in particular for a motor vehicle, which is provided with a combustion chamber (4) into which fuel can be injected and injected directly from an injection valve (9) in a first operating mode during an intake phase or in a second operating mode during a compression phase is ignitable by a spark plug (10). For the purpose of detoxifying a storage catalytic converter, an additional late injection of fuel into the combustion chamber (4) is carried out.

Description

State of technology

The invention relates to a method for operating an internal combustion engine, in particular a motor vehicle according to the preamble of claim 1. The invention also relates a control unit for one Internal combustion engine in particular of a motor vehicle according to the preamble of claim 5.

Such a method and such a control device are, for example, from the DE 196 44 407 A1 known.

With a so-called gasoline direct injection the fuel is in a homogeneous mode during the intake phase or in a shift operation during the compression phase is injected into the combustion chamber of the internal combustion engine. Homogeneous operation is preferably for full-load operation of the internal combustion engine provided while the shift operation for idle and part-load operation is suitable. Possibly. are still additional operating modes are provided. For example depending In such a direct injection internal combustion engine, the requested torque is between the operating modes mentioned.

Especially for the execution of the Shift operation requires a storage catalytic converter is present, with which nitrogen oxides are temporarily stored can be to them during a subsequent homogeneous operation in a three-way catalytic converter to reduce. This storage catalytic converter is in shift operation loaded with the nitrogen oxides and unloaded in homogeneous operation. The sulfur content of the fuel leads to poisoning of the Storage catalyst with sulfur. So it has to be repeated a so-called sulfur detoxification of the storage catalyst can be carried out. A suitable fuel / air mixture and a temperature are required for this of the exhaust gas supplied to the storage catalytic converter is required, that in normal operation of the internal combustion engine not or only at a high load is reached.

The object of the invention is a To create method for operating an internal combustion engine with that even when the internal combustion engine is operated at low Sulfur detoxification of the storage catalytic converter is possible.

This task is done in a process of the type mentioned according to the invention by the features of the characteristic Part of claim 1 solved. With a control unit the task mentioned by the characteristics of the characterizing part of claim 5 solved.

There is therefore a double injection. additionally to the injection taking place in shift operation or in homogeneous operation is additional an even later one Fuel is injected into the combustion chamber. This additional Fuel leads to a reinforced one Combustion, which in turn leads to an increase in the temperature of the exhaust gas leads. This hotter Exhaust gas then reaches the storage catalytic converter and there has a sulfur detoxification result.

The inventive method can at any time carried out become. In homogeneous operation, as well as in shift operation, the additional late injection added become. It is possible sulfur detoxification even during normal operation of the internal combustion engine of the storage catalyst without much effort perform.

In the invention, the additional Injection during the expansion phase or during the ejection phase performed by the injector. This ensures that the additional Injection later takes place as the normal injection in stratified operation or in homogeneous operation.

According to the invention, the additionally injected Fuel from the spark plug inflamed. This ensures that the additional Fuel is burned in any case and not unburned to the Environment is released.

With an advantageous further education the invention is the additional Fuel over is continuously injected for a predetermined period of time. In order to is achieved that a complete Sulfur detoxification of the storage catalyst is carried out. The time period can depend on the operating parameters of the internal combustion engine depend and can also be applicable.

It is particularly advantageous if the temperature of the exhaust gas is raised to about 650 degrees or more and when the detoxification of the storage catalyst is repeated.

This way one becomes permanent constant storage capacity of the storage catalytic converter reached.

The is of particular importance Realization of the method according to the invention in the form of a control element for a control unit of an internal combustion engine, in particular a motor vehicle is provided. It is on the control, a program is stored, in particular on a computing device on a microprocessor, executable and for executing the inventive method suitable is.

In particular, as a control element an electrical storage medium can be used, for example a read-only memory or a flash memory.

Other features, possible applications and advantages of the invention will become apparent from the following description of embodiments of the invention, which are shown in the drawing.

Claims (5)

Method for operating an internal combustion engine ( 1 ) in particular of a motor vehicle in which fuel in a first operating mode during an intake phase or in a second operating mode during a compression phase directly from an injection valve ( 9 ) into a combustion chamber ( 4 ) injected and from a spark plug ( 10 ) is ignited, and in which an additional injection during the expansion phase or during the ejection phase from the injection valve ( 9 ) is carried out, characterized in that the additionally injected fuel from the spark plug ( 10 ) is ignited, and that the additional injection is carried out for the purpose of detoxifying a storage catalytic converter. A method according to claim 1, characterized in that the additional Fuel over is continuously injected for a predetermined period of time. Method according to one of claims 1 or 2, characterized in that that the temperature of the exhaust gas is raised to about 650 degrees or more. Method according to one of claims 1 to 3, characterized in that that the detoxification of the storage catalytic converter is repeated. Control unit ( 18 ) for an internal combustion engine ( 1 ) in particular of a motor vehicle for performing a method of one or more of claims 1 to 4, wherein the internal combustion engine ( 1 ) a combustion chamber ( 4 ) in the fuel in a first operating mode during an intake phase or in a second operating mode during a compression phase directly from an injection valve ( 9 ) injectable and from a spark plug ( 10 ) is flammable, and wherein an additional injection during the expansion phase or during the ejection phase from the injection valve ( 9 ) can be carried out, characterized in that the additionally injected fuel from the spark plug ( 10 ) is ignited and that the additional injection by the control unit ( 18 ) can be carried out for the purpose of detoxifying a storage catalytic converter.