Internal-combustion engines – Engine speed regulator – Having plural throttle valve structure
Patent
1996-11-12
1998-05-05
Moulis, Thomas N.
Internal-combustion engines
Engine speed regulator
Having plural throttle valve structure
123399, 123683, 123403, F02D 4100, F02D 3300
Patent
active
057461767
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
A method and arrangement for controlling an internal combustion engine is disclosed in U.S. Pat. No. 5,014,668. There, the internal combustion engine is driven in the lower and mid load ranges with an excess of air, that is, with a lean air/fuel mixture (.lambda.>1). If the accelerator pedal position signal exceeds a pregiven position threshold value in the upper load range, then a throttle flap (that is, the air supply to the engine) is adjusted in such a manner that an essentially stoichiometric mixture (.lambda.=1) is maintained. With this measure, the advantages of an engine driven with a lean mixture can be used in the part-load range without it being necessary to accept a loss of power in the upper load range. In this way, a reduced toxic-substance emission and a reduced consumption of fuel is obtained. The adjustment of the throttle flap in order to pass from operation with a lean mixture into an operation with a stoichiometric mixture or vice versa is undertaken slowly within a pregiven time span in order to exclude jumps in torque. With this slow transition, high loads of toxic substances can arise in the exhaust gas so that a slow adjustment of the throttle flap in some operating states can have unwanted consequences.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide measures according to which the transition from lean operation into the stoichiometric operation and vice versa takes place while reducing the toxic-substance emissions and while avoiding jumps in torque.
In addition, it is a target of the procedure of the invention to indicate under which conditions a change of the type of operation appears suitable, that is, for example, in which operating state the one or other mode of operation is to be selected and on the basis of which signals or signal traces the transition is to be detected.
Furthermore, in the known state of the art, the control of the throttle flap is undertaken in all operating ranges via an electrical path, that is, a so-called electronic accelerator pedal system is utilized. Such a control system is very extensive so that the complexity and the cost to realize the control of the engine can be considerable.
According to a further aspect of the invention, a control system is therefore provided for an internal combustion engine for a lean operation in first operating states and a stoichiometric operation in second operating states which is less complex and nonetheless exhibits an adequate influence on the supply of air to the engine for a satisfactory transition from the lean region into the stoichiometric region.
DE 4,111,078 A1 provides, for traction control, a second throttle flap which is electrically actuable from its fully open position to its closed position. This is in addition to the main throttle flap in the intake system of the engine which is actuable by the driver via a mechanical path. The second throttle flap is, as a rule, in the fully open position and is actuated in the closing direction to reduce the power of the engine when there is slippage at the drive wheels.
With the procedure of the invention, a control system for an internal combustion engine is provided wherein a transition from a mode of operation with a lean mixture composition in first operating states to a mode of operation with a stoichiometric mixture composition in second operating states is ensured without a jump in torque and increased emissions of toxic substances.
It is especially advantageous that, with the procedure of the invention, an operation of the internal combustion engine with a lean mixture composition is possible in large load ranges. It is further advantageous that, at increased power requirement (for example, in the acceleration phase, during transient operation or in the upper load range of the engine), a comfortable rapid switchover to a stoichiometric mixture composition takes place; whereas, for reduced power requirement, a corresponding transition into the mode of operation with a lean mixture takes place
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"Powertrain Control System for Lean Combustion Engines" by Y. Ohyama et al, Hitachi Review, vol. 35 (1986), No. 3, Tokyo, Japan, pp. 141 to 144.
Damson Eckart
Klenk Martin
Miller Stefan
Moulis Thomas N.
Ottesen Walter
Robert & Bosch GmbH
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