DD245730A1

DD245730A1 - METHOD FOR MEASURING THE SPEED OF A COMBUSTION ENGINE

Info

Publication number: DD245730A1
Application number: DD28584585A
Authority: DD
Inventors: Dieter Schmidt; Robert Mostroph
Original assignee: Verkehrswesen Forsch Inst
Priority date: 1985-12-31
Filing date: 1985-12-31
Publication date: 1987-05-13

Abstract

Das Verfahren kann zur Messung der Drehzahl rotierender Teile von Verbrennungsmotoren benutzt werden. Ziel ist die Ermittlung der Drehzahl ohne wesentliche Mitwirkung der zentralen Einheit eines Rechners, damit diese waehrend der Messzeit andere Aufgaben erfuellen kann. Die angewendete integrierende Messung erlaubt eine Eleminierung des Einflusses der unterschiedlichen Momentanwerte der Winkelgeschwindigkeit von rotierenden Teilen eines Verbrennungsmotors und ist an verschiedene Bedingungen (Gebertyp; Groesse des Integrationsbereiches der Messung) problemlos anpassbar. Die Drehzahlermittlung kann Bestandteil eines Diagnosesystems sein, das auf einem Mikrorechner mit entsprechenden peripheren Einrichtungen realisiert wird. Die Schaltung zur Drehzahlmessung zeigt Figur 1. Fig. 1The method can be used to measure the rotational speed of rotating parts of internal combustion engines. The aim is to determine the speed without significant involvement of the central unit of a computer so that it can perform other tasks during the measurement time. The applied integral measurement allows elimination of the influence of the different instantaneous values of the angular velocity of rotating parts of an internal combustion engine and is easily adaptable to different conditions (encoder type, size of the integration range of the measurement). The rotational speed determination can be part of a diagnostic system that is implemented on a microcomputer with corresponding peripheral devices. The circuit for speed measurement shows Figure 1. Fig. 1

Description

Nachstehend soll die Erfindung an einem Ausführungsbeispiel näher erläutert werden. Die zugehörige Figur 1 zeigt eine Schaltung zur Durchführung des Verfahrens, angewendet in einem Diagnosesystem für Verbrennungsmotoren. Die gesamte Anordnung stellt eine periphere Einrichtung eines Mikrorechners dar und ist an dessen zentraler Einheit über den Datenbus angeschlossen. Diese Einrichtung erhält Impulse von einem Geber, der mit dem rotierenden Teil des Motors verbunden ist. Der Vorteiler VT mit einem einstellbaren und damit an verschiedene Gebertypen anpaßbaren Teilungsverhältnis reduziert die Anzahl der Impulse. Diese werden in dem ersten Zähler Z1 aufsummiert. Bei Erreichen eines ebenfalls einstellbaren Zählerstandes, mit dem die Größe des Integrationsbereiches, über dem die Drehzahlmessung erfolgen soll, eingestellt wird, gibt Z1 ein Anforderungssignal zur zentralen Einheit und schaltet gleichzeitig den ersten Umschalter U1 und den zweiten Umschalter U 2 in der Art um, daß die von dem Zeitgeber ZG abgegebenen Impulse abwechselnd auf den zweiten Zähler Z2 und den dritten Zähler Z3 gelangen und daß der Ausgang des jeweils anderen Zählers zum Auslesen des Zählerstandes der zentralen Einheit bereitgestellt wird. Das Anforderungssignal veranlaßt den Rechner nach jedem abgeschlossenen Integrationsbereich (i.a. ein oder zwei Umdrehungen der Kurbelwelle) zur MeßwertverarbeitungThe invention will be explained in more detail with reference to an exemplary embodiment. The associated figure 1 shows a circuit for carrying out the method, applied in a diagnostic system for internal combustion engines. The entire arrangement represents a peripheral device of a microcomputer and is connected to the central unit via the data bus. This device receives pulses from an encoder which is connected to the rotating part of the motor. The prescaler VT with an adjustable division ratio, which can be adapted to different types of encoders, reduces the number of pulses. These are added up in the first counter Z1. Upon reaching a likewise adjustable meter reading, with the size of the integration area over which the speed measurement is to be set, Z1 is a request signal to the central unit and simultaneously switches the first switch U1 and the second switch U 2 in the way that the pulses emitted by the timer ZG alternately pass to the second counter Z2 and the third counter Z3 and that the output of the other counter is provided for reading the count of the central unit. The request signal causes the computer after each completed integration area (i.a., one or two revolutions of the crankshaft) for Meßwertverarbeitung

Bei dem erfindungsgemäßen Verfahren ergeben sich gegenüber b ekannten Verfahren folgende Vorteile: In the method according to the invention, there are the following advantages over known methods:

— Durch die Verwendung eines Vorteilers VT läßt sich das Verfahren an verschiedenste vorhandene Gebertypen anpassen.- By using a prescaler VT, the method can be adapted to a variety of existing encoder types.

— Die Integrationszeit zur Erfassung der einzelnen Meßwerte ist ebenfalls variabel. Hierdurch sind Messungen, bei denen Kurzzeitschwankungen der Drehzahl gemittelt und auch Messungen während ausgewählter Teilarbeitsspiele innerhalb eines Gesamtarbeitszyklus des Verbrennungsmotors möglich. So ist es z. B. möglich, Angaben über das Verhalten einzelner Zylinderzu erhalten.- The integration time for recording the individual measured values is also variable. As a result, measurements in which short-term fluctuations in the speed averaged and also measurements during selected partial work cycles within a total work cycle of the internal combustion engine possible. So it is z. For example, it is possible to obtain information about the behavior of individual cylinders.

— Ein weiterer Vorteil des Verfahrens ist die Verwendung eines Umschalters U 2 und dessen Steuerung durch das Verfahren selbst, welches zur Entlastung der zentralen Einheit beiträgt. Es wird dadurch automatisch immer der richtige Zähler Z2 oder Z3 zur Übernahme der Meßwerte mit der zentralen Einheit verbunden.- Another advantage of the method is the use of a switch U 2 and its control by the process itself, which contributes to the discharge of the central unit. As a result, the correct counter Z2 or Z3 is always automatically connected to the central unit for taking over the measured values.

Claims

Invention claim:

A method for measuring the rotational speed of a rotating part of an internal combustion engine, wherein in a known manner a fixed predetermined number of pulses per revolution is delivered from a mounted on the rotating part, characterized in that the pulses in a prescaler (VT) by a predetermined division ratio can be reduced and counted in a first counter (Z 1), which has an output that emits a pulse itself upon reaching a predetermined number of pulses and thereby brings a first switch (U 1) in the other switching position, with pulses of a higher frequency , which are output by a timer (ZG), can pass alternately to a second counter (Z2) or third counter (Z3) and counted by these, wherein the pulse at the output of the first counter (Z 1) simultaneously a second switch ( U 2) in opposite directions to the first switch (U 1) controls, so that a connection to a be have been manufactured central unit of a computer, which is caused by the pulse at the output of the first counter (Z1) to detect the count of each resting second counter (Z2) or third counter (Z3) and further processing by the counter reading inversely proportional is a measure of the rotational speed of the rotating part, and the central unit of the computer can be released from the necessity of distinguishing the second counter (Z2) and the third counter (Z3) by the presence of the second switch (U 2).

For this 1 page drawing

Field of application of the invention

The method can be used to measure the rotational speed of rotating parts of internal combustion engines.

Characteristic of the known technical solution

In a known method (DE 3206954 A1, G01 P3 / 481) for speed and angle measurement on a rotating system, a predetermined number of pulses and additionally a zeroing signal are emitted per revolution. The speed pulses are used for the speed and angle measurement, wherein for the speed measurement between two successive speed pulses a measuring frequency is counted in a counter whose contents are taken at a new speed pulse in a memory and the counter is cleared and wherein for the angle measurement, the Drehzählimpulse in a pulse counter are counted, the contents are taken in the presence of a read signal in a second memory and the current state of the Meßfrequenzzählers in a third memory, and that the contents of the memory are read after applying the read signal in a computer or a meter for the calculation of Speed and angular position at the time of the read signal.

In this method, instantaneous values of the angular velocity are measured. If the actual rotational speed of the rotating part is to be determined, all occurring instantaneous values of one revolution must be stored in the abovementioned computer and then an average value must be formed.

Object of the invention

The aim of the method is to determine the speed without significant involvement of the central unit of the computer so that it can perform other tasks during the measurement time.

Explanation of the essence of the invention

In internal combustion engines, as is well known, the angular velocity of all rotating parts of a cycle (one or two revolutions of the crankshaft) is not constant.

If one can only use instantaneous values to determine the rotational speed, as in the above-mentioned method, it is necessary to store all the instantaneous values during a work cycle and then averaging by a computer.

The problem is to measure the actual rotational speed of the rotating part by a corresponding method so as to eliminate the influence of the different instantaneous values of the angular velocity on the measurement result, on the condition that the performance of the computer in certain time windows is not lowered by the rotational speed detection becomes.

According to the invention, the method consists in that in order to measure the rotational speed of a rotating part of an internal combustion engine from a device attached to the rotating part, a fixed number of pulses per revolution is emitted in a known manner. The pulses are reduced in a prescaler by a predeterminable division ratio and counted in a first counter which has an output which emits a pulse itself upon reaching a predetermined number of pulses and thereby brings a first switch in the other switching position, with pulses of a higher frequency , which are output by a timer, can pass alternately to a second or third counter and are counted by these, wherein the pulse at the output of the first counter simultaneously controls a second switch counter to the first switch, so that a connection to a known per se central unit of a computer, which is caused by the pulse at the output of the first counter, the count of each resting at the second or third counter is inversely proportional to a measure of the rotational speed of the rotating part, and wherein the central unit of the computercan be released from the necessity of distinguishing the second and the third counter by the presence of the second switch.