Internal-combustion engines – Engine speed regulator – Having condition responsive means with engine being part of...
Patent
1990-03-05
1991-11-26
Miller, Carl Stuart
Internal-combustion engines
Engine speed regulator
Having condition responsive means with engine being part of...
123358, 123479, F02D 3100
Patent
active
050674617
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention is based on a method and apparatus for metering fuel to a diesel engine. The fuel quantity required for the particular operating condition of a diesel engine is generally determined in dependence upon the rotational speed of the engine and from the accelerator pedal position (also in dependence upon other variables as required). Since driving is done with an excess of air, the quantity of the fresh air drawn in by suction is of only subordinate significance. Requirements for a reduction of contaminant exhaust gases and a possible reduction of exhaust particles in internal combustion engines lead, however, to the consequence that the quantity of the fresh air drawn in by suction in diesel engines is also considered in the determination of the fuel quantity.
BACKGROUND OF THE INVENTION
A method and an apparatus are known from DE-OS 28 03 750 wherein the fresh air quantity drawn in by suction is considered in the determination of the fuel quantity. Air quantity and fuel quantity are precontrolled starting with the accelerator pedal position which signals a desire for a quantity of fuel. Thereafter, the exact values are taken from multi-dimensional characteristic fields. Air quantity and fuel quantity are then controlled to these precise values. The fuel quantity is limited by limitations stored in the characteristic fields. The ratio of air to fuel (lambda) influences these limitations especially with respect to the particle exhaust. Corresponding lambda values are stored in the characteristic fields.
It has been shown that with aging of the engine, deviations between the data stored in the characteristic fields and the actual conditions of the engine occur. As a consequence of such a deviation, an increased exhaust of particles during full-load operation can often occur.
Furthermore, a control arrangement for a fuel metering system of an internal combustion engine is known from DE-OS 30 39 436. With the arrangement described here, a PI-controller determines the quantity of fuel to be injected into the engine in dependence upon the comparison between the desired lambda value and the actual lambda value. The PI-constants of the controller are stored in a characteristic field in dependence upon load and rotational speed. The controller is preferably switched out during the full-load condition.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method and apparatus with which the increased particle exhaust caused by aging is avoided with the lambda control being only active when it is necessary.
The method with the features of the main claim has the advantage with respect to the state of the art that the actual lambda value is measured directly and is applied during full-load operation for controlling the highest permissible quantity of fuel. A further advantage is seen in the simple technique of the replacement of conventional lambda control of the fuel quantity by a minimum value selection. The influence of system-conditioned dead times is avoided by a rapid control to an effective "catch curve" and a subsequent slow lambda control.
Further advantages and configurations of the invention become evident from the measures provided in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention is shown in the drawing and is more carefully described in the description which follows.
FIG. 1 shows a block circuit diagram wherein the essential elements for fuel quantity open-loop control and fuel quantity closed-loop control are contained;
in FIG. 2, the essential elements are shown which are required for controlling the highest permissible fuel quantity,
FIG. 3a shows the time course of different fuel quantity signals,
FIG. 3b shows the time course of the lambda probe signal,
FIG. 3c shows the time course of the start signal for the ramp,
FIG. 4 illustrates the dependence of the ramp slope on the rotational speed of the engine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
In FIG. 1, 100 identifies a diesel en
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patent: 4476829 (1984-10-01), Straubel
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patent: 4589392 (1986-05-01), Wirz
patent: 4709335 (1987-11-01), Okamoto
patent: 4730586 (1988-03-01), Yamaguchi
patent: 4836166 (1989-06-01), Wietelmann
patent: 4881404 (1989-11-01), Siegl
Joachim Ernst-Ulrich
Kull Hermann
Miller Carl Stuart
Ottesen Walter
Robert & Bosch GmbH
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