Internal-combustion engines – Combustion chamber means combined with air-fuel mixture...
Patent
1995-09-01
1997-07-08
Argenbright, Tony M.
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
F02P 515
Patent
active
056450346
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND INFORMATION
A knock control is already known from German Patent Application No. 40 08 170, and in this the ignition angle is set by means of a characteristic diagram and, when knocking occurs, the ignition angle is retarded in order to prevent this knocking. Subsequently, this ignition angle is brought to the ignition angle of the characteristic diagram again by a return in steps in the direction of advance. Furthermore, the operating range of an internal combustion engine is subdivided into different ranges, so that, when a range is left, the ignition angle current at that moment is stored and, when the internal combustion engine is operated once more in this range, this stored ignition angle is outputted as a starting value. Now in the event of a change of range, the previously stored ignition angle may differ from the optimum ignition angle, so that, in the state of the art, the return of the ignition angle is carried out at increased speed. However, particularly when there is a large difference between the stored ignition angle and the optimum ignition angle guaranteeing operation near the knock limit, this method has the disadvantage that torque jumps detectable on the engine occur as a result of the ignition-angle jumps.
SUMMARY OF THE INVENTION
An advantage of the method according to the present invention is that the above-described ignition-angle jumps are reduced and therefore no detectable torque jumps occur on the engine. It is to be considered a further advantage that the exhaust-gas behavior of the engine is improved by the avoidance of unfavorable ignition angles. Furthermore, it is advantageous, for averaging, to employ all the ignition-angle retard values or the initial and final value of the ignition-angle retard values which are outputted in this range. However, the formation of a geometrical, quadratic or harmonic average of all the ignition-angle retard values of a range is also possible. Finally, it is advantageous to provide an ignition-angle change limitation, so that, when this ignition-angle change limitation is exceeded during the change from one operating range to another, the current ignition angle is brought to the stored ignition angle at increased speed, with the result that torque jumps are avoided.
This ignition-angle change limitation does not take effect when knocking occurs, so that, in the event of knocking, a sufficient ignition-angle shift takes place in any case for knock-free operation. It may also be mentioned that the adaption of the ignition angle, if the stored ignition angle deviates from the current ignition angle by less than a predeterminable difference amount, the step width and the step height of the ignition-angle return can be changed over to another set of parameters with slower control, so that a slower torque change and therefore a quiet running of the internal combustion engine are possible.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram for carrying out the method of adaptive knock control according to the present invention.
FIG. 2 shows an adaption characteristic diagram according to the present invention.
FIG. 3 illustrates the variation in the ignition angle in the method according to the present invention.
DETAILED DESCRIPTION
FIG. 1 shows a block diagram for carrying out the method of adaptive knock control. The internal combustion engine (not shown) is operated by means of a control unit 1 which has a knock-sensor evaluation circuit 2, a microprocessor 3, an analog/digital converter 4 and an ignition output stage 5. On the engine block of the internal combustion engine there are one or more knock sensors 6 which are connected to the knock-sensor evaluation circuit 2. The knock-sensor evaluation circuit 2 is connected to the microprocessor 3 via an analog/digital converter 4. Furthermore, the recorded parameters of the internal combustion engine are fed to the microprocessor 3. Thus, for example, the load L which is determined, for example, from the throttle-flap angle position or the intake-pipe pressure, t
REFERENCES:
patent: 4527526 (1985-07-01), Akasu
patent: 4617895 (1986-10-01), Sakakibara et al.
patent: 4699105 (1987-10-01), Jensen
patent: 5243942 (1993-09-01), Entenmann et al.
Baeuerle Michael
Entenmann Robert
Haeming Werner
Hilbert Wolfgang
Rothhaar Ulrich
Argenbright Tony M.
Robert & Bosch GmbH
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