SU1740764A1 - Method for identification of knocking combustion of fuel-air mixture in internal combustion engine - Google Patents

Abstract

The use of improving the accuracy of estimating the presence of detonation in a controlled cylinder is provided by successively generating signals from the first, second, and third sectors. Vibration signals are measured within the first two sectors, and measured signals are compared in the third sector. Moreover, the sector signals are arranged in the expansion stroke from the moment corresponding to the position of the piston in the upper dead point of the cylinder under control, up to the moment corresponding to the position of the piston in the upper dead point of the next cylinder engine operating parameters of the first and second sectors provide measurement of the vibration signals and their selection by zones of the most likely occurrence and complete absence of detonation. In this case, the vibration signal is measured within the entire informative zone and the influence of extraneous noise on the vibration signals recorded within the sectors is reduced. 2 hp f-ly, 2 ill. sl C

Description

The invention relates to the diagnosis of internal combustion engines (DIFS), in particular to methods of controlling the workflow, and can be used for forced ignition internal combustion engines.

Various methods are known for isolating a detonation combustion of an air-to-air mixture (FA) of a multi-cylinder engine, for example a method where detonation recognition is performed by comparing (subtracting) the current signal and the average amplitude of the signal of the detonation sensor in the absence of detonation recorded during a certain time after the ignition signal .

The main disadvantage of this method is that the recognition occurs in the constant time interval and after the arrival of the ignition signal. It is known that with an increase in the crankshaft rotation frequency (FWVM) the period of the signal decreases, therefore, recognition in the constant time interval leads to an unjustified increase in this interval at high FER values, which increases the likelihood of falling into the extraneous information interval. Conversely, with a decrease in the PNVKV, the constant time interval takes up a smaller part of the total increasing period of the signal, which is not enough to poll the entire detonation-hazardous zone of the sensor signal.

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Synchronization of the constant time interval from the moment of ignition also leads to a decrease in recognition accuracy due to excessive information, since the moment of sparking does not depend on the onset of the detonation mode of the fuel assembly.

The closest to the invention is the method according to which the formation of two constant in crankshaft angle (UPKV) sectors of a given duration, where in the first sector formed to the top dead center (TDC) of the controlled cylinder, information on mechanical DVB DVS noise, and in the second sector, formed immediately after the TDC of the cylinder to be monitored, information about the detonation component of the common UKB sensor signal is read. Information is read as peak values of the signals, and information is zeroed at the end of the detonation sector. Special means are provided for signal processing, resulting in detonation defined as the voltage Ua proportional to the percentage superiority of the peak voltage QVB, measured in the second sector, over The peak voltage UVB measured in the first sector, or instead of the percentage ratio Ua, can be attributed to some known maximum voltage UaMaKc, i.e. l

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The main disadvantage of the known device is the selection of the first sector at the position up to TDC, where gas pressure builds up in ICE cylinders due to the previous ignition of the fuel assembly. For example, research has revealed the random nature of the constituent vibrations from combustion in this particular sector. In addition, the value of the second sector is not justifiably increased, which leads to the reading of false information about detonation.

The purpose of the invention is to improve the recognition accuracy of the fuel assembly detonation combustion in each cylinder of an internal combustion engine.

The goal is achieved by the first and second crankshaft angles in the engine running mode of detecting the detonation combustion of the air / fuel mixture, and signals proportional to detonation in each engine cylinder are measured in these sectors, all sectors being arranged sequentially in an expansion stroke.

control cylinder in the interval after determining its TDC and prior to determining TDC of the next engine in accordance with the order of operation of the engine cylinders, the beginning of the first sector is placed through a constant angle of rotation of the crankshaft from the TDC of the controlled cylinder, and the duration of the sector is not less than the specified part tact, the beginning of the second sector is placed through a constant angle of rotation of the crankshaft interval after the first, and its duration is chosen not less than a predetermined part of the stroke, form Tille sector following the second, which compares the signal levels received in the first and second sectors, and results judged by the presence or absence of detonation in the cylinder is controlled, whereupon t reset information.

In addition, the method provides for the same duration of the first and second sectors, and the third sector is placed directly after the second.

FIG. 1 shows the waveforms of processes in the internal combustion engine, respectively, in the presence of detonation processes in a controlled cylinder of the engine; in fig. 2 - the same, in the absence of detonation processes.

FIG. 1 and 2, the following notation is entered: curve 1 - signal of TDC mark; curve 2 - the process of combustion in the cylinder of the engine; curve 3 - vibration signal occurring before TDC; curve 4 - vibration signal from detonation; curve 5 is the total vibration signal from detonation and vibration of non-detonation origin; curves 6, 7, 8 are the first, second, and third sectors, respectively; curve 9 is a signal proportional to the intensity of detonation; curve 10 is the generated detonation assessment signal.

The signal is implemented as follows.

With the engine running, the position of the TDC is determined using the UPKV sensor. A signal corresponding to the beginning of the first sector is formed through the angle specified for each type of engine after the mark of TDC. Moreover, this signal is formed at the moment of crankshaft position, corresponding to the maximum value of gas pressure in the cylinder, which is 10-12 ° UPKV after TDC.

The duration of the generated signal of the first sector is taken not less than 20 ° UPKV. Within the first sector, the detonation signal (curve 4) is measured and stored. The beginning of the signal of the second sector is formed with a delay of a given angle at the end of the signal of the first sector, while the duration of the signals of the first and second sectors are taken to be equal. Within the second sector, the detonation signal (curve 5) is also measured and stored. At the same time, the duration of the first and second sectors is limited to the value corresponding to half of the OPCW between successive flashes in the engine cylinders in accordance with the number of cylinders and engine responsiveness minus the delays between the beginning of the first sector and TDC, the beginning of the second and the end of the first sector and the duration of the third sector required to convert information.

At the end of the signal of the second sector, a signal of the third sector is formed, within which the signals obtained within the first and second sectors are compared, by subtracting the second signal from the first one. The difference from the zero or close to it value of the signal obtained from the comparison results indicates the presence of detonation in the controlled cylinder of the internal combustion engine (curve 10 of FIG. 1).

Sequential generation of signals from the first, second, and third sectors with the specified parameters on the extension line provides for the measurement of vibration signals and their selection by the zones of the most likely occurrence and complete absence of detonation. This provides a detonation measurement. At the same time, the vibration signal is measured within the entire informative zone and the influence of extraneous noise on the vibration signals recorded within the sectors is reduced, which provides an increase in the accuracy of estimating the presence of detonation in a controlled ICE cylinder.

Claims (3)

Claim 1. The method of recognizing a detonation combustion of an air-fuel mixture in an internal combustion engine, in which the angular position of the crankshaft is monitored while the engine is running, captures the moment corresponding to the position of the piston of the cylinder under control at top dead center, produces signals of the first and second sectors within which the measurement of the vibration signal, and the results of the comparison of signals measured within two sectors, assess the presence of detonation in a controlled cylinder, characterized in that, in order to improve accuracy, a signal is generated from the third sector of the crank angle, within which the signals are compared, measured within the first and second sectors, and the signals of the first, second and third sectors are formed successively in the expansion stroke of the cylinder under control, within the limits of the angle of rotation the crankshaft from the moment corresponding to the top dead center in the controlled cylinder to the moment corresponding to the upper dead point in the next order cylinder; at the same time, the beginning of the signal of the first sector is placed through a constant angle of rotation of the crankshaft interval from the top dead center of the controlled cylinder, the beginning of the signal of the second sector have a constant angle of rotation of the crankshaft at the end of the signal of the first sector, and the duration of the signals of the first and second sectors take at least a predetermined part of the cycle in the controlled cylinder, and after the signal of the third sector, the information about the measured vibration signals is reset compare. 2. The method of clause 1, which is different the fact that the duration of the signals of the first and second sectors are equal. 3. The method according to paragraphs. 1 and 2 are distinguished, and with the fact that the signal of the third sector is formed immediately upon the termination of the signal of the second sector. 31 V AND 2 J RE tLt / t m with/ 36 , w t-C2 7 sz at phage. one 27 / l H2 Xj 23 H | fHWWHH lUH HW HttH HH 26 277 / ten