Measuring and testing – Vehicle chassis – Steering
Patent
1995-12-26
1997-08-12
Dombroske, George M.
Measuring and testing
Vehicle chassis
Steering
324379, 324380, G01M 1500
Patent
active
056567707
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention starts from a method for testing a spark-ignited internal combustion engine according to the generic type of the main claim. In the technical book by P. PAULSEN, "Elektronische Motortestgerate" [Electronic Motor Testing Devices], Franzis-Verlag, 1977, chapter 4.12 describes electronic rpm counters on pages 78-84, each having a monostable multivibrator at the input. The known rpm counters derive a pulse-shaped signal from the ignition system of the internal combustion engine, which signal is converted into a square wave signal by means of the monostable multivibrator. The use of the monostable multivibrator reduces the influence of interfering signals which are suppressed during the active phase of the multivibrator.
It is the object of the invention to propose a method for testing a spark-ignited internal combustion engine which allows the supply of a signal derived from the ignition system which signal is largely free of undesired signal portions.
This object is solved by the characteristics defined in the main claim.
ADVANTAGES OF THE INVENTION
It is provided according to the invention that a first pulse of the pulse group of the pulse-shaped signal derived from the ignition system, which signal allocates a pulse to each switching operation occurring in the ignition system, starts a retriggerable timer whose active phase is longer than the maximum interval between the pulses of a potentially occurring pulse group. With this measure it is possible to suppress the pulses of the group which follow the first pulse. The method according to the invention suppresses particularly those pulses corresponding to every switching operation in the ignition system which occur after the first pulse of a spark band ignition.
The spark band ignition provides that, at least in certain operating conditions of an internal combustion engine, for example, at low rpm's or during cold starting, a pulse spark group instead of a single ignition spark is generated in a fast time sequence. The pulse spark group is set to a predetermined range of the crankshaft angle. Therefore, it can be assumed that the-interval between the pulses of a pulse group to which the time to be predetermined for the timer must be matched is known.
An essential advantage of the method according to the invention is that devices for the testing of a spark-ignited internal combustion engine, particularly the trigger segment, can continue to employ the known circuitry. The method according to the invention supplies the device with the information regarding which pulses are to be suppressed. The method according to the invention allows, for example, a detection of the rpm of the internal combustion engine from pulses which occur in the ignition system without resulting in disturbances or measuring errors during a spark band ignition due to the further pulses of the pulse group.
Advantageous modifications and improvements of the method according to the invention ensue from the dependent claims.
An advantageous embodiment provides that the time to be predetermined for the timer is longer than the maximum expected ignition spark duration. The maximum ignition spark duration may be longer than the maximum interval between the pulses of a pulse group. This measure accomplishes a further increased resistance to interfering signals. Such a disturbance could take place, for example, when the spark breaks.
A particularly advantageous modification provides that the retriggerable timer is switched off when the rpm of the internal combustion engine exceeds a predetermined threshold value. A spark band ignition is not provided at higher rpm's. The proposed measure thus allows a processing of ignition pulses even at the highest rpm's at which the intervals between the ignition sparks enter the time range allocated to the retriggerable timer.
Another embodiment, which might be combined, if required, with the already described switching-off of the retriggerable timer provides that the time which is to be predetermined for the timer is set as a funct
REFERENCES:
patent: 4661778 (1987-04-01), Anderson
patent: 4893085 (1990-01-01), Taruya et al.
patent: 5387870 (1995-02-01), Knapp et al.
P. Paulsen: "Elektronische Motortestgerate" [Electronic Motor Testing Devices], Franzis-Verlag, 1977, pp. 78-84.
Dittmann Karl-Heinz
Fischer Uwe
Dombroske George M.
McCall Eric S.
Robert & Bosch GmbH
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