Electricity: measuring and testing – Electrical speed measuring – Speed comparing means
Patent
1986-12-05
1989-02-28
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Electrical speed measuring
Speed comparing means
73518, 324163, 324166, G01P 356
Patent
active
048089206
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
One of the most important operating characteristic values for controlling and/or regulating an internal combustion engine is the speed of the internal combustion engine. The speed value is picked up by means of corresponding transmitters and, if need be, prepared for the further processing by means of signal adaptation and amplifications. It is known to monitor the tachometer to determine whether it delivers an output signal or not. If an output signal is present it is used for the control and/or regulation, while a non-present output signal of the tachometer triggers corresponding erroneous functions.
It is now possible that the tachometer delivers an output signal, but that the same does not have any meaningful value. Such meaningless speed signals may be generated by electromagnetic stray effects, by defects of the tachometer, or by mechanical defects of for example, the rotating part of the internal combustion engine which is in operating connection with the tachometer. The disadvantage of the known monitoring devices of tachometer signals consists in that they do not recognize such meaningless signals as being erroneous, but feed them for further processing as correct speed signals. Therefore, in the known systems no plausibility monitoring of the tachometer signals is performed.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a method for monitoring a tachometer signal in which meaningless signals are recognized and only the actual correct tachometer output signals are fed for further processing. In the method in accordance with the invention a plausibility monitoring of the tachometer signals is performed.
In accordance with a particular further embodiment of the invention this object is attained in that for each new tachometer output signal limit values are advanced which at least are dependent from the last tachometer output signal. If the new tachometer signal exceeds these limit values or falls below the same, the monitoring recognizes this tachometer signal as being not meaningful. However, if the new tachometer signal is within the preestablished limits, such a speed signal is then fed for further processing.
In a further advantageous design of the invention a marker is set for each recognized meaningless speed signal, which results in that a speed signal which had been recognized to be correct is only fed for further processing when this marker had been available for a defined preestablished duration of time. Therefore, with the assistance of this marker is is possible to prevent a continuous and rapid reciprocating switching between meaningless and correct speed signals and thereby between a normal operation and erroneous functions.
Finally, it is also possible to perform the monitoring of the tachometer signal if this signal has exceeded a preestablished value. This is advantageous in that interferences may be eliminated which may be generated during the start of the internal combustion engine.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a block circuit diagram of the device in accordance with the invention;
FIG. 2 illustrates a flow chart diagram of the method in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The subsequently described exemplified embodiment relates to monitoring of the output signal of a tachometer. Principally it is also possible with the assistance of the method in accordance with the invention to monitor given signals, the changes of which are performed within known limits. The described exemplified embodiment may be realized in different ways and manners, for example,
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Brauninger Jurgen
Holmes James
Sieber Albrecht
Eisenzopf Reinhard J.
Mueller Robert W.
Robert & Bosch GmbH
Striker Michael J.
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