Knocking recognition method

FIELD: mechanical engineering; internal combustion engines.

SUBSTANCE: invention is aimed at increasing efficiency of discrimination of signals caused by knocking in internal combustion engine from signals caused by other noises in engine. Method is implemented by means of at least one detonation combustion sensor and signal processing unit installed after detonation combustion sensor and provided with at least one comparator. Output signal from detonation combustion sensor is compared after processing by comparator with variable reference value of level formed basing on preceding output signals of said combustion detonation sensor. Reference value of level passes into comparator through low-pass filter, and comparator indicates presence or absence of knocking basing on results of comparing. Tracking of reference value of level or calculation of value of input signal of low-pass filter are carried out at least by two different methods. Method is chosen depending on presence or absence of dynamic mode of engine operation.

EFFECT: improved efficiency of discrimination of signals caused by knocking.

5 cl, 6 dwg

 

The present invention relates to a method for recognition of detonation knock, detonation occurs when the fuel combustion in the internal combustion engine (ice).

It is known that in internal combustion engines equipped with a control system for detonation, use sensors detonation combustion, the output signals of which can determine the presence or absence of detonation combustion. Recognition detonation is used, for example, the structure-borne noise sensors, used for systems with a single gauge of detonation combustion system with two sensors detonation combustion engines to be installed in specified places of the engine block, or system, in which each cylinder is provided on the gauge of detonation combustion. The main problem faced when processing signals from the sensors detonation combustion is in the Department due to detonation knock signal from signals due to the remaining noise. Since the signal detonation and knock signal background noise depends on various conditions or operating modes of the internal combustion engine, the analysis on the presence or absence of detonation knock conduct, as it is known, depending on the shaft speed of the engine.

In the description it is known from DE-P 4332711 device detected is of detonation knocks the process of processing the output signals from the two sensors detonation combustion to detect detonation knock. In the microprocessor on the basis of the previous signal detonation knock formed the reference level values, which are compared with the actual output signal corresponding to the processed sensor signal detonation combustion. If the level of this signal exceeds the reference level value, this fact indicates the presence of detonation and in accordance with this, for example, the ignition system is given control signal, which ensures the elimination of detonation in subsequent cycles of combustion. With the purpose to take into account the dependence of the background signal noise and signal detonation knock on the frequency of rotation of the motor shaft and to provide optimal detection of detonation knocks, you can change the reference level value depending on the frequency of rotation, with the increase in rotational speed is increased and the reference level value.

To improve the efficiency of selection signals due to detonation knock proposed recognition method detonation knock in internal combustion engines. This method involves the use of at least one sensor detonation combustion and is installed behind the signal processing unit, having at least one comparator, which compares the processed output signal of the sensor detonation combustion is a variable reference level value, based on the previous output signal of this sensor detonation combustion. The reference level value supplied to the comparator through a low-pass filter, and a comparator depending on the result of this comparison establishes the fact of presence or absence of detonation.

The solution to the above problem is achieved by tracking the reference level values or the calculation of the value of the input signal of the lowpass filter perform at least two different methods, the choice of either method depends on the presence or absence of dynamic modes of the internal combustion engine.

The advantage of the proposed invention in the method of recognition of detonation knock is possible reliable detection of detonation knock irrespective of the intensity of noise throughout the range of operating conditions of the engine. This advantage is achieved due to the fact that in addition to the usual tracking the reference value level provides for more effective tracking this reference level values in the dynamic mode, primarily those of internal combustion engines, which are characterized by a significant increase in the noise level when operating in the dynamic mode. The proposed method allows to eliminate erroneous detection of detonation knock in the engine, the noise level which offset the em average, accordingly, in the engine, which in some modes is accompanied by a noise level above the average, because in this case provided associated with the above-mentioned advantage of the correction reference value level.

In preferred variants of the invention, the reference level rkr(new) can be formed depending on the pre-established presence or absence of detonation and the presence or absence of the dynamic mode using the following equations:

a) rkr(new)=(1-1/KRFTP)•rkr(previous)+1/KRFTP•ikr,

b) rkr(new)=(1-1/KRFTP)•rkr(previous)+l/KRFTP•(ikr/ke) or

in) rkr(new)=(1-1/KRFTP)•rkr(previous)+1/CRTR•(rkr(previous)•ke),

where rkr(previous) means the previous reference level value, KRFTP is a witness coefficient, ikr means the noise level in the current combustion cycle, and ke is a coefficient.

With particular advantage consists in the fact that more effective tracking of the reference level values in dynamic mode allows faster to track this reference level value. This fast tracking is achieved by reduction in the presence of the dynamic mode of the corresponding coefficient in comparison with the normal mode.

The existence of detonation can be installed in the case, when the value vrkr, calculated as the ratio of the level values of the detonation noise ikr in the current cycle combustion to the previous reference level rkr(previous), exceeds the value of ke.

In addition, when setting the new reference level values can be taken into account also the previous values defined when the fact of detonation, and when forming the reference level rkr may optionally be taken into account, does not exceed the ratio virkr threshold value ke•(KRRPN•(ke-1)+1), where ke characterizes the recognition threshold knock knock, a KRRPN is a factor that takes values from 0 to 1.

Below the invention is described in more detail on the example of some variants of its implementation with reference to the accompanying drawings on which is shown:

figure 1 is a possible embodiment of a device for recognition of detonation knock, allowing proposed in the invention methods of recognition of detonation,

figure 2 and 3 is a flowchart which illustrates operations performed in the implementation of the two proposed in the invention methods for recognition of detonation knock,

figure 4 - characteristics of various quantities used to calculate the reference values of the level.

Shown in figure 1 embodiment, the device for recognizing deton the traditional knock in internal combustion engines has two sensors 10, 11 detonation combustion, for example in the form of structure-borne noise sensors that are installed in predetermined locations of the block of cylinders of internal combustion engine 12. Granted these sensors 10, 11 detonation combustion signals S1, S2 depend on the noise of the engine and may present unwanted sounds (noise) and may present a detonation knock. For reliable recognition of detonation issued by the knock sensor signals must be divided into these components, respectively, to distinguish them from the generated sensor signals. With this purpose, issued by the sensors 10, 11 detonation combustion signals S1 and S2 are served at the appropriate subsequent processing in the signal processing unit, the output signal S3 which indicates the presence or absence of detonation.

Unit 13, the signal processing can be performed in a separate schema or can be part of the microcomputer. Unit 13, the signal processing can be integrated, for example, in the control unit of the engine. The microcomputer 14, performing the further processing of the signals S3, coming from block 13 signal processing, may constitute, for example, the microprocessor control unit. The microcomputer 14 controls the devices 15 of the ignition system and/or device 16 of the system of injection of fuel depending on the signal S3, which allows to determine under what or absence of detonation, and regulates the way the flow of the combustion in the individual cylinders of the engine.

For optimum control of the combustion in the microcomputer 14 receives other signals, for example from sensor 17, which represents, for example, sensor throttle position. Obviously, you can use any number of sensors, the output signals which, after appropriate pre-treatment received in the microcomputer and processed therein. Shown in figure 1 embodiment, each of the signals fed to the respective input, which are indicated by the positions E1 and E2, while the output signals are sent to the outputs, indicated by the positions A1, A2 and A3.

The actual recognition detonation knock, i.e. the determination of the presence or absence of detonation, occurs in block 13 of the signal processing. Part of this block 13 of the signal processing in the present embodiment, execution includes at least one amplifier 18 with adjustable gain, in which the output signals S1 and S2 sensors 10 and 11 of detonation combustion. At the input of the amplifier in each case receives the output signal for that cylinder, which cylinder, in which at the moment is actually happening combustion of fuel, specified by the respective program. With the output of the amplifier with the United bandpass filter 19, of the subject in which filtering the amplified signals are allocated components with typical detonation knock frequencies. With the output of bandpass filter connected to the demodulator (detector) 20, such as a rectifier. The output signal of the demodulator 20 are integrated in the integrator 21 and then integrated signals KI received at the first input of the comparator 22.

To another input of the comparator 22 receives the reference signal, respectively, the reference level signal Ref generated, for example, using 5 filter 23 of the lower frequencies by averaging pre-treated as specified in the signals from sensors detonation combustion. How is formed the actual reference level signal and what values they take, is the main object of the invention is described in more detail below.

Specific device separate block elements 13 of the signal processing is not significant for the invention and therefore not described in detail. Unit 13, the signal processing may be performed entirely in the digital processing unit such as a microprocessor.

Using shown in figure 1, the device recognition process of detonation, respectively, knock knock occurs as follows. The sensors 10, 11 detonation combustion registration shall irout noise created by the engine, and generates the appropriate signals S1 and S2 in block 13 of the signal processing. In this unit, these signals are appropriately filtered and amplified. By comparing the integrated signals KI detonation knock with the reference level signal Ref generated signal S3 indicating the presence or absence of detonation.

Specifically, the process of recognition of detonation knock in internal combustion engines using sensors detonation combustion, working as structure-borne noise sensor, can be explained on the example of the flowchart presented in figure 2. In this embodiment, the first step SCH1 is determined by the noise level ikr in the current cycle of combustion. Based on this noise ikr step SCH3 determines the magnitude of the virkr, calculated as the ratio of noise ikr registered on the current cycle of combustion, averaged over multiple combustion cycles in the same cylinder, the noise, the so-called reference level rkr, while previously in step SCH2 introduced the previous reference level rkr(previous).

Then calculated in step SCH3 attitude virkr is checked in step SCH4 order to determine whether it exceeds the coefficient ke, an appropriate threshold value recognition detonation knock. If the relation virkr=ikr/rkr(previous) exceeds this porogo the second value ke recognition knock knock, this indicates the presence of detonation, and in this case, given the signal KL. Thus, also holds the following condition: if the value of ikr is greater than the value rkr(previous)•ke, it indicates the presence of detonation and outputs a corresponding signal KL.

If at step SCH4 it is determined that the value virkr does not exceed the value of ke, it indicates the absence of detonation, and therefore, the transition to step SCH5 on which the reference level rkr(previous) when the engine is in bezdetnaya mode is calculated recursively according to the following formula:

rkr(new)=(1-1/KRFTP)•rkr(previous)+1/KRFTP•ikr.

Value KRFTP is the so-called witness coefficient. This witness coefficient can be properly aligned with a specific type of internal combustion engine.

Thus obtained a new reference level rkr(new) describes the background noise created by the engine during its operation without detonation. In the next cycle of execution of the above procedure is calculated in step SCH5 new reference level rkr(new) is equal to the step SCH6 to the previous reference level rkr(previous) and used for the next calculation relationships virkr. If at step SCH4 combustion is registered as detonation, the value measured for this cycle combustion noise ikr not fully include the W in the calculation of the reference level rkr. How this value is taken into account in the calculations in the presence of detonation depends on the presence or absence of dynamic mode. With this purpose in step SCH7 is checked whether the internal combustion engine in dynamic mode. To determine the presence or absence of such a dynamic mode can, for example, to test whether a significant change in speed.

In the absence of dynamic mode, the value of the measured noise level ikr is divided by the value of ke and accounted for to avoid increasing the reference level rkr resulting detonation knock. In this case, the new reference level rkr(new) is calculated in step SCH8 by the following formula:

rkr(new)=(1-1/KRFTP)•rkr(previous)+1/KRFTP•(ikr/ke).

Not be taken into account in the calculations of detonation combustion cycles in principle impossible, as presented by this knock noise in the dynamic mode components are also present, due to the natural increase of the noise level internal combustion engine, and therefore, such noise is necessary to register with the other noises.

In order to eliminate with the rapid and significant increase in background noise in dynamic mode (the presence of which indicates a received in step SCH7 solution) erroneous detection of detonation, so what. in order to eliminate erroneous acceptance of combustion cycles, suddenly creating a more loud noise, detonation, provided the following two measures introduced at the time of engine operation in dynamic mode: acceleration tracking the reference values of the level by selecting a smaller factor KRFTP and increasing recognition threshold detonation knock.

Despite these countermeasures against wrongful taking of other noises for detonation in internal combustion engines, and engines with above-average increase in the noise level, for example due to misalignment of the piston, it is possible erroneous detection of detonation knock at their actual absence. However, such combustion, mistakenly taken for detonation, results in the above described process of determining the share of noise ikr generated in the current cycle of combustion, by dividing by the value of ke for inclusion in the calculation of the reference level rkr unnecessarily slow tracking of the estimated background noise rkr. The discrepancy between estimated and actual values of the background noise can result in the subsequent occurrence of additional errors in the detection of detonation. Because each time it detects detonation knocks response is ultimately changing the angle of operazioni the ignition to the side later the result of a wrong-making other noise for detonation may be a corresponding reduction in power and efficiency, in the case of such erroneous recognition of detonation is absolutely unnecessary. Therefore, the above-described reference level value when there is detected at step SCH7 dynamic mode of operation of the engine is calculated according to the invention another method that reduces the probability of false acceptance of other noise for detonation and yet still provide reliable detection of actually having a place of detonation.

Depending on the presence or absence of dynamic regime, the new reference level value is calculated either according to the formula specified for step SCH8 or formula specified for step SCH9. In this case, in step SCH6 previous reference level rkr(previous) every time is replaced by its new value rkr(new), which step SCH3 again used to calculate the relationship.

Thus, when the detected detonation, when in fact taking place detonation or wrong when making other noise for detonation in the above method in the presence of dynamic mode reference level rkr(new) is calculated according to the following modified formula:

rkr(new)=(1-1/KRFTP)•rkr(previous)+1/KRFTP•(rkr(previous)•ke).

The value of the rkr(previous)#x02022; ke corresponds to the noise level, which is still not taken for detonation. In other words, in contrast to the way in which does not distinguish between the presence and absence of a dynamic mode, in this case to track the reference level values in the calculations included a larger value, which, however, clearly follows from the mean value of the noise level. This method of determining the reference values of the level eliminates erroneous acceptance of the other noise for detonation, and thus useless power reduction and efficiency

Figure 3 shows the following variant of the invention, in which in the presence of dynamic mode accounted for tracking the reference value level. This method differs from the method illustrated in figure 2, the only additional step SCH10, which provides additional query threshold. When it detects detonation in step SCH4 and identifying the dynamic mode at step SCH7 (if any actually having a place of detonation or erroneous recognition of detonation) operation is performed directly provided on the specified step SCH10. This step is virkr is compared with the threshold value ke•(KRRPN•(ke-l)+1), while the ratio KRRPN can take values in the interval from 0 to 1 (0, 1), lying in predlahat ke to ke 2. If the specified threshold is not exceeded, then the reference level value is calculated in step SCH9 by the following formula:

rkr(new)=(1-1/KRFTP)•rkr(previous)+1/KRFTP•(rkr(previous)•ke).

If the value of the ratio virkr beyond this threshold, then the new reference value is calculated according to the following specified for a step SCH8 formula, which corresponds to the formula previously used in the case of detected detonation

rkr(new)=(1-1/KRFTP)•rkr(previous)+l/KRFTP•(ikr/ke).

Additional introduction of such a variable threshold allows to use when the value KRRPN equal to 0, still tracking mode reference level value, and Vice versa, is KRRPN equal to 1, provides fast tracking the reference values of the level that is necessary for the internal combustion engine, respectively, of the motors with the rapid increase of the noise level when the dynamic change of the rotation frequency. Thus it is possible for a long period of time to reduce the probability of erroneous recognition of detonation in dynamic mode and the associated power loss and reduced efficiency

Figure 4 (4A, 4B and 4C) show examples obtained by simulating the characteristics for the following values:

virkr_P: noise ikr generated in the current cycle of combustion, to the average value of the noise level, registered the date in the last cycle combustion in the same cylinder,

kekref: threshold detection detonation knock,

rkrref: reference level value=smoothly changing the average value of the last cycle combustion

eingangneu: the value used to calculate the actual reference level,

ikrref: the level of noise generated in the current cycle combustion for the coefficient KRRPN were selected respectively the values 0 (figa), 0,5 (figb) and 1.0 (pigv). Line B_kl indicates the presence of a detected detonation (high level) or in the absence of detonation (low level).

1. The method of recognition of detonation knocking in the internal combustion engine (ice) using at least one sensor detonation combustion and is installed behind the signal processing unit, having at least one comparator, which compares the processed output signal of the sensor detonation combustion engines with a variable reference level value, based on the previous output signal of this sensor detonation combustion reference level value supplied to the comparator through a low-pass filter, and a comparator depending on the result of this comparison establishes the fact of presence or absence of detonation, characterized in that the tracking reference level values or the calculation of the values of the input signal of the lowpass filter done is make at least two different methods, the choice of either method depends on the presence or absence of dynamic modes of the internal combustion engine.

2. The method according to claim 1, characterized in that the reference level rkr(new) form depending on the pre-established presence or absence of detonation and the presence or absence of the dynamic mode using the following equations:

a) rkr(new)=(1-1/KRFTR)·rkr(previous)+1/KRFTR·ikr,

b) rkr (new)=(1-1/KRFTR)· rkr(previous)+1/KRFTR·(ikr/ke) or

in) rkr(new)=(1-1/KRFTR)·rkr(previous)+1/KRFTR·(rkr (previous)·ke),

where rkr (previous) means the previous reference level value, KRFTP is a witness coefficient, ikr means the noise level in the current cycle combustion and ke is a coefficient.

3. The method according to claim 1 or 2, characterized in that the existence of detonation sets in the case when the value virkr, calculated as the ratio of the level values of the detonation noise ikr in the current cycle combustion to the previous reference level rkr (previous), exceeds the value of ke.

4. The method according to claim 2, characterized in that when you specify a new reference level values also take into account previous values defined when the fact of detonation.

5. The method according to claim 2, characterized in that when forming the reference level rkr addition take into account do not exceed the ratio virkr threshold value ke· (KRRPN·(ke-1)+1), where ke characterizes the recognition threshold knock knock, a KRRPN is a factor that takes values from 0 to 1.



 

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