Internal-combustion engines – Engine speed regulator – Responsive to deceleration mode
Patent
1997-10-06
1998-11-24
Argenbright, Tony M.
Internal-combustion engines
Engine speed regulator
Responsive to deceleration mode
123481, 123493, F02D 4112
Patent
active
058394095
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND INFORMATION
German Patent Application No. DE 43 28 835 A1 describes a method that determines an additional injected quantity on a cylinder-selective basis after reactivation following injection suppression operations for individual cylinders. Examples of suppression operations include automatic slip control (ASR), deactivation while coasting, or an engine speed or vehicle speed limiter. In this context, the initial value upon reactivation of fuel delivery depends on the number of injections that were suppressed to the cylinder in question. After reactivation, the additional injected quantity is modulated back down to zero, as a function of the number of injections into the cylinder in question after suppression thereof was ended. The additional injected quantity required at the time of reactivation is based on a permanently predefined injection value that is modulated up with a certain time constant.
It is the object of the present invention to indicate a method for determining an additional injected quantity upon reactivation of at least one suppressed cylinder of an internal combustion engine which improves emissions and fuel consumption values as compared to the existing art.
SUMMARY OF THE INVENTION
The present invention provides a method for determining the additional injected quantity by multiplying a load-dependent wall-film quantity, read from a characteristic curve at the time of activation, by a correction factor. This correction factor is modulated up, during the coasting deactivation time until reactivation, with a first time constant. After reactivation, the previously calculated additional injected quantity is modulated back down with a second time constant.
Improved emissions and fuel consumption value result from deriving the additional injected quantity upon reactivation from a current value for the wall-film quantity.
BRIEF DESCRIPTION OF THE DRAWINGS
The Figure shows a block diagram for a method for determining an additional injected quantity upon reactivating of an internal combustion engine.
DETAILED DESCRIPTION
Cylinder-selective injection suppression is usually performed, for example, with automatic slip control (ASR), during coasting, and in the case of engine speed or vehicle speed limiting. If rotation speed falls below a minimum threshold, or if the throttle is opened, the transition occurs from coasting deactivation (i.e. from injection suppression of individual cylinders) to cylinder-selective reactivation. The sequence of cylinders to be reactivated and their number can be defined by way of specific suppression patterns. If the change in throttle valve angle or rotation speed is small, a staged (soft) reactivation occurs; in the event of large changes in throttle valve angle or rotation speed, reactivation is abrupt (hard). During reactivation, a cylinder-selective additional fuel quantity is required in order to build back up the wall film in the air intake duct that was degraded during suppression, which can be of different durations for the individual cylinders.
The Figure depicts a block diagram which illustrates how the additional injected quantity necessary upon reactivation is determined for a cylinder. Block 1 contains a characteristic curve for the load-dependent wall-film quantity in the air intake duct. From this characteristic curve, the particular present value of the wall-film quantity is read off as a function of the load signal t1. At node 2, a value WOFF, which indicates the minimum wall film at idle, is added to the wall-film quantity WF(k) (ki is a time index) taken from characteristic curve 1. This value WOFF is taken from a characteristic curve 3 dependent on engine speed n, or from a characteristics diagram dependent on engine speed and engine temperature. This minimum wall-film quantity WOFF can, however, also be taken into account in characteristics diagram 1.
A sample-and-hold circuit in block 4 retains that value of the wall-film quantity WFM1=WF(k)+WOFF that is present when a reactivation signal B-WE appears at block 4. This samp
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Bottcher Klaus
Denz Helmut
Kloos Alfred
Pfitz Manfred
Argenbright Tony M.
Robert & Bosch GmbH
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