Internal-combustion engines – Combustion chamber means combined with air-fuel mixture...
Patent
1991-07-25
1992-08-04
Nelli, Raymond A.
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
F02P 514
Patent
active
051349809
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a knock generation control system for engines for controlling a knock control factor (for example, ignition timing, air/fuel ratio, supercharging pressure or the like) by detecting a knock generated in an engine, and, more particularly, to a knock generation control system for engines including the setting of a knock decision level.
BACKGROUND ART
Generally, a knock decision level V.sub.KD is produced by multiplying a mean level of a knock sensor signal by a constant K. In such a KCS (knock control system), there is a problem that an optimum value of K changes due to manufacturing disperison, variations with time, etc. of engines, knock sensors and so on, which makes it difficult to perform accurate knock detection. In order to solve this problem, a system has been proposed which pays attention to the fact that, as shown in FIG. 15, the shape of a frequency distribution curve (broken line) of representative values of a knock sensor signal, in the case where a knock is generated, is distorted in the direction of a region of greater representative values of the knock sensor signal, in the case where a knock is generated, is distorted in the direction of a region of greater representative values of the knock sensor signal as compared with that of a frequency distribution curve (solid line) in the case where no knock is generated, and which contemplates to automatically correct a knock decision level on the basis of a degree of the distortion (for example, a relation in magnitude between the area of a region 1 and that of a region 2 in FIG. 15) (for example, see JP-A-62-267574).
However, when the region 1 or region 4 in FIG. 15 is used as a parameter for correcting the knock decision level as in the above system, a long time is required before a sufficient amount of data for correcting the knock decision level is obtained, since the probability for a representative value to fall within the region 1 or region 4 is small. Accordingly, there is a problem that a long time would elapse before the knock decision level is automatically corrected to have an adequate level and, as a result, inadequate knock detection is made during that time.
DISCLOSURE OF THE INVENTION
The present invention is made to solve the above-mentioned problem, and an object of the present invention is to provide a system which enables automatic correction of a knock decision level so as to make it have an adequate level within a short period of time.
FIG. 1 is a functional block diagram which comprehensively illustrates a functional relation between constituent elements of the system of the present invention.
In order to attain the above-mentioned object, the present invention proposes a knock generation control system for engines which comprises, as shown in FIG. 1:
a knock sensor for detecting a knocking phenomenon generated in an engine;
standard deviation detecting means for detecting a quantity SGM corresponding to a standard deviation of a frequency distribution of logarithmic conversion values lV of said representative values V;
cumulative percentage point detecting means for detecting a value V.sub.P of a cumulative percentage point of said frequency distribution;
knock decision level setting means having u-value calculating means for calculating a value of u, which becomes greater as the rotational speed of said engine increases, and setting a knock decision level V.sub.KD in accordance with said quantity SGM corresponding to the standard deviation, and said value V.sub.P of the cumulative deviation, and said value of u;
knock detecting means for detecting generation of a knock in accordance with said representative values V and said knock decision level V.sub.KD and producing a knock generation detection signal; and
adjusting means responsive to said knock generation detection signal from said knock detecting means for adjusting a knock control factor which is used to suppress generation of a knock.
It should be noted that the value of the cumulative percentage point of the fre
REFERENCES:
patent: 4711212 (1987-12-01), Haraguchi et al.
patent: 4967710 (1990-11-01), Komurasaki et al.
patent: 5000149 (1991-03-01), Miyama
patent: 5029566 (1991-07-01), Komurasaki
Sakakibara Koji
Yamada Hirohiko
Nelli Raymond A.
Nippondenso Co. Ltd.
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