Method for controlling fuel metering in multiple injection operating mode

Abstract

The invention relates to two methods for controlling a fuel metering of a direct-injection internal combustion engine (10) in a multiple injection operating mode according to which at least two fuel injections into a cylinder (12) are carried out during a compression cycle of the cylinder (12) of the internal combustion engine (10) by means of at least one injection valve (22). The invention provides that a pressure (rail pressure, pR), under which the fuel is stored in front of the injection valve (22), is preset in such a manner and/or injected fuel portions of the individual injections of a combustion cycle and/or a total fuel quantity, which is injected during a multiple injection, are varied in such a manner as to prevent a forthcoming valve opening time (Deltat) of the injection valve (22) from falling below a preset valve opening time (DeltatK) during at least one injection of a combustion cycle. The inventive measures ensure, with simple means, a precise fuel metering in the multiple injection operating mode and thus enable an application of the multiple injection operating mode over wide operating ranges, particularly also in the low load operating mode and idle operating mode.

Description

technical field [0001] The invention relates to a method for controlling fuel metering of a direct-injection internal combustion engine in multi-stage injection operation, wherein at least two fuel injections into a cylinder of the internal combustion engine can be carried out within a working cycle of a cylinder of the internal combustion engine by means of an injection valve. Background technique [0002] It is known that there are many different ways to increase the exhaust gas temperature of an internal combustion engine after a cold start and thus accelerate the warm-up of the catalytic converters connected in series in order to replace them in the operational readiness. [0003] It is known that delay adjustment is required in order to achieve maximum efficiency in the ignition angle, that is, the moment at which the air-fuel mixture in the cylinder is ignited, during hot operation. By delaying the adjustment of the ignition angle, the working efficiency of the combust...

AI Technical Summary

Problems solved by technology

This problem of inaccurate fuel metering is especially serious when the engine is running at low load, especially in the idling range. At this time, the valve opening time is very short due to the small amount of fuel required.

Another difficulty to consider is that as yet there is no regulation scheme that provides feedback on the air-fuel ratio produced by two or more injections

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