Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
2002-05-24
2004-05-04
Gimie, Mahmoud (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S406290
Reexamination Certificate
active
06729300
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for regulating knocking in an internal combustion engine, particularly of a motor vehicle, having the following steps:—determining a knocking combustion for a calculated first base ignition angle in one or more cylinders of the internal combustion engine originating from a previous operating condition; and setting a new, second base ignition angle taking into account the existing operating condition.
BACKGROUND INFORMATION
Methods are known for regulating knocking to avoid knocking combustion in an internal combustion engine cylinder by setting a suitable base ignition angle. The base ignition angle is defined as the earliest admissible angle prior to which knocking combustion does not occur in the combustion engine. Since knocking combustion may occur independently in each cylinder of the internal combustion engine, the corresponding base ignition angle must be set individually for each cylinder. The respective value of the base ignition angle is derived from the sum of a basic ignition angle value, an ignition angle correction value, and an ignition angle retardation value. The ignition angle correction is used to compensate for the effects of temperature and engine speed in the determination and calculation of the base ignition angle. The ignition angle retardation is thus provided as an active element in regulating knocking. Accordingly, the base ignition angle defines a currently determined cylinder-specific knocking limit which changes while the internal combustion engine is running.
However, an active knocking regulation method can only determine and set the actual knocking limit, and thereby also the actual base ignition angle with a corresponding ignition angle retardation, if the control circuit, including the knocking regulation (as the regulating unit) and the internal combustion engine (as the regulated system), is closed. This means that knocking regulation must actually act on the internal combustion engine, that is to say on each cylinder individually in order to ensure that the actual ignition angle has the same value as the base ignition angle.
Moreover, a setpoint ignition angle is defined for a torque conversion for actions synchronized with the crankshaft. The setpoint ignition angle is a setpoint variable for efficiency reduction derived from an engine torque controller using an ignition retardation angle. The setpoint ignition angle is limited upwardly to the earliest admissible ignition angle, that is to say the respective base ignition angle, and downwardly to a latest admissible ignition angle. This setpoint ignition angle is used as the actual ignition angle when active torque intervention is present, and is therefore output to the ignition. If no active torque intervention is present, the base ignition angle is used as the actual ignition angle.
When active torque intervention is present, the knocking regulation circuit is interrupted, with the result that the value of the actual ignition angle is equal to the setpoint ignition angle, and not equal to the base ignition angle. Since the knocking regulation circuit has been interrupted, the knocking regulation system can only register changes in the actual knocking limit with a delay, if at all. The disadvantageous result is an unacceptable increase in the frequency of knocking.
SUMMARY OF THE INVENTION
The method according to the present invention for regulating knocking in an internal combustion engine, particularly of a motor vehicle, is characterized in that the second base ignition angle is set to produce good operating and knock regulating conditions via a query with respect to the relative size of a compensating setpoint ignition angle and the first base ignition angle. The provision of a query step before the ignition angle retardation makes it possible to distinguish among different operating modes with respect to the relative size of the setpoint ignition angle and the base ignition angle, and to initiate appropriate measures. In such a case, the capability to detect an operating mode wherein the setpoint ignition angle is smaller than the prevailing base ignition angle is particularly advantageous so that the fastest possible and highly effective knocking regulation can be initiated via an appropriate ignition retardation angle. The appropriate ignition retardation angle can then be set using a variable and adjusted retardation value that is defined by the relationship between the setpoint ignition angle and the existing base ignition angle.
The query preferably provides for two decision options. Since only the operating mode where the setpoint ignition angle is smaller than the optimal ignition value is to be identified, a corresponding query with two decision options (yes or no) is appropriate.
In the event that the setpoint ignition angle is smaller than the first base ignition angle, the query is advantageously followed by ignition angle retardation by an adjustment value which is set anew and is formed from the sum of a previously determined, constant retardation value and an adjusted, variable retardation value. With an ignition angle retardation characterized in this way, that is to say one which is generated using a retardation value that is set anew based on the sum of a constant value and an adjusted value, fast and reliable knocking regulation may be achieved in particularly effective manner by appropriate selection of the adjusted value.
Advantageously, the ignition angle is retarded to set the second base ignition angle in a single regulating step. By appropriate selection of the adjusted retardation value, the ignition angle retardation for determining the second base ignition angle may be performed advantageously in a single regulating step. This allows reliable and particularly fast knocking regulation. Unacceptably frequent knocking combustion caused by the difference between the calculated (theoretical) and the actual base ignition angle (actual knocking limit) may be avoided by the provision of multiple constant, relatively small regulating steps.
The adjusted, variable retardation value is advantageously defined as the difference between the larger, first base ignition angle and the smaller setpoint ignition angle. An adjusted and variable retardation value defined in this way allows the second base ignition angle to be set using an ignition angle retardation in a single regulating step.
In the event that the setpoint ignition angle is greater than or equal to the first base ignition angle, the query is advantageously followed by an ignition angle retardation with an adjustment value that matches the previously determined, constant retardation value. Since in this operating mode the setpoint ignition value is not smaller than the first optimal ignition value, and there is accordingly no need to take into account an adjusted, variable retardation value to retard the ignition value, the adjustment value may be defined using a previously determined, constant retardation value.
Advantageously, the ignition angle is not retarded if knocking combustion does not occur with the first base ignition angle. If this further, alternative operating mode for combustion is considered, it is possible to create a closed regulating circuit for effective, reliable and fast knocking regulation of an internal combustion engine taking into account a variety of different operating conditions.
Further advantageous embodiments of the present invention are explained in the description.
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Franke Steffen
Haussmann Martin
Gimie Mahmoud
Kenyon & Kenyon
Robert & Bosch GmbH
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