Data processing: measuring – calibrating – or testing – Calibration or correction system – Sensor or transducer
Reexamination Certificate
1999-06-16
2001-11-27
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Calibration or correction system
Sensor or transducer
C073S116070, C073S117020
Reexamination Certificate
active
06324483
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an angular acceleration transducer and a use of the angular acceleration transducer, for example in connection with detection of misfiring of internal combustion engines. The angular acceleration transducer may also advantageously be used for detection of torsional oscillations in drive shafts, for example in electric trains and motor cars, etc. The angular acceleration transducer may thus be used in connection with drive devices of various kinds.
A misfire of an internal combustion engine indicates a fault condition which, depending on the nature of the fault, may have more or less serious consequences. To avoid the complications which may arise, it is therefore of great importance, as a first step in eliminating the fault, to be able to detect a misfire as quickly as possible after the occurrence thereof.
If an internal combustion engine misfires, this normally means that guaranteed values of the contents and composition of the exhaust gases cannot be kept. This is one of the most important reasons for the desirability of rapidly detecting a misfire.
There are a plurality of different reasons for the misfiring of an internal combustion engine. A misfire may, for example, be due to a fault in the electric ignition system, incorrect time for ignition, a faulty spark plug, too fat or too thin fuel mixture, etc. The intention of the present invention is to enable, by simple means and independently of the reason for the fault, detection of misfiring in order thus to be able to rapidly initiate measures such that the internal combustion engine may resume a faultless operating state again.
BACKGROUND ART, THE PROBLEMS
The known technique for detecting misfiring is primarily based on two different methods, namely, measuring the rotational speed of the flywheel or crankshaft of the internal combustion engine, or measuring the torque of the crankshaft of the internal combustion engine.
The most commonly used method is based on measurement of the rotational speed of the flywheel. This measurement occurs either instantaneously with the aid of some kind of analog speed sensor, or as a mean value; in which case the measurement is normally digital. Then, an analysis is made of the very small differences in the rotational speed which arise, especially during misfiring, in order to determine whether or not misfiring has occurred. From a purely general point of view, this method is very sensitive to measurement errors and does not function satisfactorily for all loads and speeds.
An embodiment comprising the above method is described in U.S. Pat. No. 5,239,473 “Method and system for detecting the misfire of an internal combustion engine utilizing angular velocity fluctuations”. In this case, the rotational speed of the crankshaft and electronic signal processing are utilized. After the speed signal has been processed to reduce random faults and external disturbances, the signal may be utilized in four different described methods of calculation to obtain information as regards the torque developed in each cylinder. This results in a vector with M dimensions for the behaviour of each cylinder for each cycle of the internal combustion engine. Here, M represents the number of cylinders of the engine. By analysis of this vector with the aid of statistical decision theory, it is possible, according to the patent specification, to obtain information about any misfire.
The other method, as mentioned above, comprises directly measuring the torque in the crankshaft. The principle as such functions very well for detecting misfiring. However, the problem is that the application of a torque transducer requires quite an extensive intervention in an existing engine design and is, therefore, not particularly attractive to the automobile industry.
An embodiment comprising this method is described in WO 92/10733 A2, “Engine misfire, knock or roughness detection method and apparatus”. The method comprises determining, at regular intervals, the mean and standard deviation of a number of signals originating from torsional stresses of the crankshaft, determining the difference in mean value between consecutive measurements, determining the ratio between this difference and the standard deviation and then comparing the difference against a threshold value. This ratio for a given cylinder is then compared with one or more corresponding ratios for other cylinders in the internal combustion engine. It is further clear from the patent document that magneto-strictive sensors may be used to obtain a measure of the torsional stresses.
As will have been clear from the above description, misfiring of internal combustion engines is detected on the basis of measurement of the rotational speed of the crankshaft or the torque developed in the crankshaft and by means of advanced and extensive analytical and statistical methods. It has also been mentioned that there are problems in connection with the sensitivity to measurement errors when analyzing speed signals and in connection with the application of current measuring transducers and, in particular, with the application of torque transducers.
REFERENCES:
patent: 4606005 (1986-08-01), Ribbens
patent: 4898025 (1990-02-01), Weyland
patent: 5200899 (1993-04-01), Ribbens et al.
patent: 5239473 (1993-08-01), Ribbens et al.
patent: 5287735 (1994-02-01), Klauber et al.
patent: 5824890 (1998-10-01), La Palm et al.
patent: 5954784 (1999-09-01), Inada et al.
patent: 6006155 (1999-12-01), Wu et al.
patent: 6062071 (2000-05-01), Henn et al.
patent: 1538929 (1979-01-01), None
patent: WO 97/48894 (1997-12-01), None
Asea Brown Boveri AB
Connolly Bove & Lodge & Hutz LLP
Hoff Marc S.
Pretlow Demetrius
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