Measuring and testing – Test stand – For engine
Patent
1992-01-31
1993-10-26
Myracle, Jerry W.
Measuring and testing
Test stand
For engine
36443107, G01M 1500
Patent
active
052555607
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for measuring the irregular running of an internal combustion engine. As a rule, irregular running results from misfiring. It is detected, for example, from the occurrence of knocking noises near a knocking sensor or as the result of considerable fluctuations in the mean pressure of the combustion chamber. Other processes make use of fluctuations in the angular velocity of the crankshaft. The case at hand concerns such a process.
BACKGROUND OF THE INVENTION
DE 25 07 138 (U.S. Pat. No. 4,044,234) discloses measuring the angular velocity in a given angular interval before the top dead center and the angular velocity in a same angular interval after the top dead center of a cylinder situated in the expansion stroke. If the difference between the two values falls below a specified threshold value, it is concluded that the combustion in the monitored cylinder has failed. The mentioned differential measurement is performed for all the cylinders of an internal combustion engine. When one of the differential values falls below the specified threshold value, a misfiring is recognized.
Measurements for individual cylinders are also performed in a process as described in an article by I. Geiger al titled "Running Irregularity an Input Variable for Control Processes" in the conference report for the 8th Viennese Motor Symposium 1897, S. 277-295. A measurement is performed for each cylinder in an angular interval after the top dead center for three successive expansion strokes V1, V2 and V3. The time period T.sub.-- V1, T V2 or T.sub.-- V3 in which the crankshaft rotates by a specified angular interval is always measured. The runningirregularity value LUW is calculated according to the following formula: V2),.vertline. (1) V3)
The thus calculated running-irregularity value is applied in an idle speed control.
Unlike the above-mentioned processes, runningirregularity values are able to be determined not by applying successive expansion strokes of a same cylinder in the equation (1) indicated above as expansion strokes V1, V2 and V3 in which measurements are performed, but rather by applying immediately successive expansion strokes. Such a process is described in an article by V. Bianchi et al. titled "A Simple and Objective Process for Measuring Irregular Running" in MTZ 39/1978, Nr. 7/8, S. 1-5. The mentioned article does not specifically describe processes which make use of calculated runningirregularity values.
In practice, however, the process just mentioned leads again and again to false information, since the influences of the road and gear unit prove to be disturbing. Therefore, one has been confronted for quite some time with the problem of specifying a more reliable process for measuring running irregularity.
SUMMARY OF THE INVENTION
In the process according to the present invention, the running-irregularity values LUW are calculated according to equation (1) with time periods for different groups of cylinders, the maximum value and the minimum value of the calculated groups are determined, and the difference between the minimum value and the maximum value is calculated. This measure has the advantage, inter alia, that the running irregularity caused by ignition misfiring can be separated from the running irregularity caused by driving on rough roads. In the latter case, changes in angular velocity can occur on the crankshaft which are similar with respect to frequency and amplitude variations to those caused by ignition misfiring. All the running-irregularity values then rise above the commonly specified threshold value. If, however, the maximum and minimum value are determined, as mentioned, and the mentioned difference is formulated, it turns out that the magnitude of the differential value is largely independent of changes in the moment of rotation that are transferred from the drive wheels to the crankshaft, but that this differential value is, on the contrary, considerably dependent on ignition misfirings.
The mentioned time periods
REFERENCES:
patent: 3972230 (1976-08-01), Hanson et al.
patent: 4123935 (1978-11-01), Maringer
patent: 4608536 (1986-08-01), Jacobs et al.
patent: 5040412 (1991-08-01), Wannenwetsch
patent: 5044195 (1991-09-01), James et al.
patent: 5044336 (1991-09-01), Fukui
Klenk Martin
Moser Winfried
Myracle Jerry W.
Robert & Bosch GmbH
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