RU2528780C2 - Method and device for identification of knocks at changing ice operating conditions - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention can be used at designing control system for ICE 2 running on several types of fuel. Identification of knocks at changing the type of fuel consists in registration of characteristic of signal (ikr) describing the ICE housing noise and definition of base level of background noise (rkr) by filtration in low-pass filter (LPF) LPF filtration factor (TPF) is varied during transition from one fuel to the other. Note here that magnitude of said factor is set to lower value that moment. Occurrence of knocks is defined proceeding from threshold value (SW) to be coordinated at changing of fuel type. Proposed device comprises housing noise registration unit 5 to record the characteristic of signal (ikr) and knocks identification unit 4 to register aforesaid signal and to determine its base level (rkr). Adjustment is performed by changing the throttle position, amount of fed fuel or ignition dwell angle.

EFFECT: lower probability of false operation of control system.

7 cl, 3 dwg

Description

FIELD OF THE INVENTION

The present invention relates to the recognition of knocking sounds in internal combustion engines (ICE), especially in ICE, which optionally can operate on different types of fuel.

State of the art

For recognition of detonation knocks, ICEs are usually equipped with body noise sensors that detect body noise of the engine block of the engine and provide signals characterizing such body noise and proportional signals. Detonation knock recognition is based on the integration, respectively, of the averaged filtered and rectified signals characterizing the case noise and the reference levels calculated on their basis. The integration of signals characterizing the case noise is usually performed only during the time interval during which detonation is possible and the duration of which is determined by one or more measuring intervals within the internal combustion engine operating cycle. To recognize a knock, the signals characterizing the body noise and the reference level are processed or analyzed in the knock timing system.

Modern ICE can operate on several types of fuel, while the mode of operation of the internal combustion engine, i.e. its management is coordinated with the specific type of fuel the engine is running on. The transition to a different type of fuel during the operation of the internal combustion engine is accompanied by a rapid change in its noise characteristics. Although when changing the operating modes of the internal combustion engine, usually there is a sharp change in the measuring intervals, the position of which changes significantly in time due to the change in the ignition timing, the reference level with which the actual signal characterizing the body noise is correlated to detect detonation knocks can only adapt to the rapidly changing delay noise characteristics, since it is determined by integration, respectively averaging. For these reasons, under certain circumstances, the possibility of erroneous recognition of detonation knocks in their actual absence is not excluded, or, conversely, the possibility of unrecognized detonation knocks in their actual presence.

In addition, immediately after changing the operating modes, for example, when switching from the operating mode on (liquefied) natural gas to the operating mode on gasoline, the propensity of the engine to detonate can increase significantly. With an instantaneous change of operating modes, it is assumed that the engine’s tendency to detonate immediately after switching from the natural gas mode to the gas mode does not differ from the engine’s detonation tendency when it runs exclusively on gasoline. In fact, however, shortly after changing the operating modes, strong detonation appears, which must be prevented.

Based on the foregoing, the present invention was based on the task of developing a method and device that would avoid the unrecognition or erroneous recognition of detonation knocks when changing engine operating modes.

SUMMARY OF THE INVENTION

This problem is solved using the method claimed in claim 1, as well as using the device claimed in the corresponding independent claim.

One of the objects of the invention is a method for recognizing knocking when changing operating modes of an internal combustion engine (ICE). This method consists in registering the characteristic of the signal characterizing the body noise of the internal combustion engine, depending on the characteristics of the signal characterizing the body noise of the signal, its reference level corresponding to the parameters of the background noise generated by the engine is determined, and the fact of the appearance of a detonation knock is established depending on the reference level. The reference level characterizing the case noise of the signal is determined depending on the process of changing the operating modes of the internal combustion engine, i.e., for example, depending on whether the internal combustion engine is currently changing or not.

For recognition of detonation knocks on the basis of a signal characterizing the body noise of the engine block, the reference level is determined, which reflects the parameters of the background noise generated by the engine. A signal characterizing the case noise instantly detected by the case noise sensor is correlated with this reference level, and the presence of a knock is recognized based on the results of this correlation. When changing the operating modes of the internal combustion engine, a rapid change in the background noise created by it often occurs, which requires appropriate coordination of the reference level.

When using conventional methods for determining the reference level, it usually only changes slowly when changing the operating modes of the internal combustion engine and therefore only gradually adapts to the changing noise characteristics of the engine. In such a case, in the process of changing the operating modes, the actual signal characterizing the case noise to a greater extent differs from the reference level, and therefore the possibility of erroneous recognition of the detonation knock in its actual absence is not excluded, respectively, the possibility of unrecognized detonation knock in its actual presence. For this reason, it is proposed that when changing the engine operating modes, it is faster to coordinate the reference level with the instantaneous parameters of the background noise generated by the engine than when the internal combustion engine operates in one of the modes.

In addition, the fact of the appearance of a knock can be established depending on the threshold value, which is agreed upon during the change of operating modes. In this way, when changing operating modes, which is primarily associated with a change in the noise characteristics of the internal combustion engine, it is possible to increase or decrease the sensitivity of recognition of detonation knocks.

The reference level can be determined during the period of time during which the change of operating modes occurs, primarily depending on the characteristics of the signal characterizing the case noise during the second period, which is shorter than the first period, while outside the period of time in which the change of operating modes occurs, the reference the level is determined depending on the characteristics of the signal characterizing the case noise during the first period. The foregoing means that before or after the process of changing the operating modes, the reference level is determined, for example, by averaging during the first period, while in the process of changing the operating modes, the reference level is determined by averaging during the second period, which is shorter in duration than the first period.

In yet another embodiment, the reference level can be determined by averaging the levels characterizing the package noise signal within the corresponding period or by integrating the characteristics of the registered package noise signal within the corresponding period.

To determine the reference level characterizing the case noise of a signal, it can be filtered in a low-pass filter using a low-pass filter coefficient, which is selected for a period of time during which a change of operating modes occurs, a smaller value than outside it.

Each of the operating modes of the internal combustion engine can correspond to its operation on fuel of one of different types, while the beginning of the period of time at which the change of operating modes occurs corresponds to a moment that depends on the end of the first operating mode. The operation of internal combustion engines on different types of fuel usually requires reconfiguration of the engine control system, and therefore, at the same time as the process of changing operating modes begins, or soon after its start, the background noise created by the engine changes.

The process of changing operating modes may primarily include working in a mixed mode in which the internal combustion engine runs on both types of fuel, and the beginning of the period of time during which the change of operating modes corresponds to the moment of the end of the first operating mode, or the moment in which the share to the first mode of operation in the general mode of operation of the internal combustion engine, reaches a predetermined value.

The duration of the period of time during which the change of operating modes occurs can be set constant or may depend on the moment of the final transition to the second operating mode.

In the process of changing the operating modes, it is possible to set the lead time of the ignition timing to change the actual ignition timing set for the internal combustion engine to a later one, and after a certain period of time, the value of such lead time of the timing of the ignition is smoothly or stepwise reduced. Changing the ignition timing to a later one can significantly reduce the likelihood of detonation knocking in the process of changing operating modes and soon after.

In addition, the lead of the ignition timing can be set depending on the temperature of the engine coolant and / or the temperature of the intake air.

In order to limit the check for the presence of detonation knocks to only those time periods during which detonation can occur, it is possible to envisage registration of the characteristic characterizing the body noise signal only at those time intervals during which the appearance of detonation knocks is possible in the internal combustion engine.

Another object of the invention is a device for recognizing a knock when changing operating modes of an internal combustion engine (ICE). Such a device has a housing noise registration unit for recording the characteristics of the signal characterizing the body noise in the internal combustion engine, and a detonation knock recognition unit for recording the characteristics of the body noise characterizing the signal, to determine its reference level, which corresponds to the parameters of the background noise generated by the engine, in depending on the characteristics of this signal characterizing the case noise and to establish the fact of the appearance of a detonation knock depending It differs from the reference level, and differs in that the detonation knock recognition unit for determining the reference level characterizing the case noise signal is configured to filter it in a low-pass filter using a low-pass filter coefficient, which is selected for the period of time during which the change of modes work of a smaller size than outside of it.

Another object of the invention is a motor system having an internal combustion engine and the above device.

Another object of the invention is a computer program product containing program code, which when executed by a data processor provides the implementation of the above method.

Brief Description of the Drawings

Below the invention is described in more detail by the example of some preferred variants of its implementation with reference to the accompanying drawings, which show:

figure 1 is a schematic view of a motor system with a function for recognizing detonation knocks,

figure 2 is a detailed view of a knocking knock recognition unit in the motor system shown in figure 1, and

on figa-3B - temporal characteristics of the signals, reflecting the nature of the change in the lead of the ignition timing, changes in the reference level for the recognition of detonation knocks, respectively, changes characterizing the modes of operation of the signals.

Description of Embodiments

Figure 1 shows a motor system 1 with ICE 2, the operation of which is controlled by a control unit 3. The control unit 3 is, for example, a component of a common common electronic engine control unit and can control all or some of the functions necessary for the operation of the engine 2.

ICE 2 is configured to operate on different types of fuel, such as, for example, natural gas (compressed natural gas) or gasoline, while one or another engine operating mode can be set automatically or manually through the control unit 3, i.e. the driver. The control unit 3 controls the operation of the engine 2 by supplying it with MS signals that can be used to set, for example, the position of the throttle valve, the amount of fuel injected (for example, by adjusting the opening and closing times of the fuel injectors), ignition times and other parameters.

In addition, a detonation knock recognition unit 4 is provided, into which from the engine block 2, for example, on its cylinder block, the body noise sensor 5, SS signals characterizing the body noise are received, which are issued, for example, in the form of an electrical quantity, and which based on such of signals can determine whether detonation combustion occurs in ICE 2 or not. When a knock is detected, a signal KS indicating the occurrence of a knock is issued to the control unit 3.

When changing the operating modes of the ICE, which is determined by the control unit 3 or is determined on the basis of an external signal, the control unit 3 issues a US signal to the detonation knock recognition unit 4, indicating a change in the US signal, according to which the knock recognition unit 4 can determine the moment of changing the internal combustion engine operation modes .

The recognition of detonation knocks by the unit 4 intended for this is based essentially on the correlation of the signals characterizing the case noise detected by the case noise sensor 5 with the reference level rkr. The reference level rkr should reflect the background noise generated by ICE 2 in the current mode of operation.

The reference level rkr is determined by averaging or integrating signals characterizing the case noise for a certain period of time, while the measurements take into account only those time intervals (measuring time intervals) in which a knock should be expected, i.e. signals characterizing the case noise are processed only at those time intervals in which the fuel-air mixture is located in the cylinders, the spontaneous ignition of which can lead to the appearance of a knock (explosion). Averaging, respectively, integration, as a rule, is performed over several similar time intervals, usually during one or more working cycles of ICE 2.

The average value of the signals characterizing the case noise corresponds to the conditional background noise generated by the engine, which can vary depending on the operating modes of the engine 2. Usually, when the engine is running on the same type of fuel, the background noise generated by the engine changes only relatively slowly, and therefore averaging is performed at that time. during which the reference level rkr can be matched with possible changes in the background noise generated by the engine. Averaging is usually performed by an integrator or low-pass filter, for which its low-pass filtering characteristic can be adjusted, for example, using the low-pass filtering coefficient TPF. The reference level rkr can be determined in a computational cycle in a discrete way based on the instantaneous signal ikr characterizing the case noise as follows:

rkr (k + 1) = ikr (k + 1) TPF + rkr (k) (1-TPF),

where k denotes the cycle number. The time constant of the low-pass filter is set by the duration of the cycle and corresponds approximately to the quotient of dividing the duration of the cycle by the low-pass filter coefficient.

The above calculations for determining the reference level rkr are performed continuously, and therefore, the reference level rkr is usually consistent with a change in the signal characterizing the case noise. Thus, the reference level always reflects the actual background noise generated by the engine.

When changing operating modes, the tendency of ICE to detonate can significantly increase. This occurs primarily when changing from a natural gas mode to a gas mode. In addition, when changing one operating mode to another, the background noise generated by the engine changes relatively abruptly, and therefore, when taking the above low-pass filtering coefficient or the above low-pass filtering characteristic as the basis, the reference level only gradually reflects a change in the background noise created by the engine. Thus, in the transition phase, when changing the engine operating modes, a situation may arise in which the reference level rkr and the actual signal SS characterizing the case noise will significantly differ from each other, due to which, under certain conditions, the possibility of erroneous recognition of the detonation knock as such under its actual absence or the possibility of erroneous unrecognition of the detonation knock with its actual presence.

Therefore, when changing operating modes, the knock recognition unit 4 changes the low-pass filtering coefficient TPF used to calculate the reference level. In other words, in the process of changing the operating modes indicated by the corresponding signal US, the reference level rkr is quickly changed in accordance with the changed signal characterizing the case noise (generated by the engine background noise). To do this, increase the low-pass filtering coefficient TPF, respectively, change the time constant or perform another similar action. The low-pass filtering coefficient TPF may be changed in the knock recognition unit 4 based on a signal indicating a change in the signal US, or the corresponding low-pass filter coefficient may be output to the knock recognition unit 4 by the control unit 3.

Fig. 2 is a flowchart illustrating a knocking knock recognition process in the block 4 intended for this purpose. The above-described reference level calculation is performed by the first multiplier element 13, the summing element 14, and the second multiplier element 11 depending on the low-pass filtering coefficient TPF. To obtain an updated reference level rkr, the value of the signal ikr characterizing the case noise is multiplied in the first multiplier 13 by the low pass filter coefficient TPF, and then the result is added to the summing element 14 with the last calculated multiplied in the second multiplier 11 by (1-TPF) reference level rkr.

The calculated reference level rkr and the actual signal ikr characterizing the case noise are supplied to the comparison unit 12 with a threshold value (threshold block).

The threshold block 12 receives the threshold value SW, which can be set constant or can be variable and set, for example, by the control unit 3 depending on the operating mode of the engine 2. If the difference is too large or the ratio between the actual signal ikr characterizing the case noise ( actual noise) and reference level rkr (background noise generated by the engine), i.e. when the threshold value SW is exceeded by the above result, the presence of a detonation knock is detected, which is accompanied by the issuance of a signal KS indicating its appearance. Instead of the indicated difference or the indicated ratio, other relationships between the reference level and the actual case noise signal can also be used.

The threshold value of SW can be coordinated primarily in the process of changing operating modes. So, for example, when changing the first operating mode in which the internal combustion engine is quieter to the second operating mode in which the internal combustion engine 2 is louder, the threshold value SW can be increased in comparison with the threshold value SW adopted during the operation of the internal combustion engine in the first mode, and vice versa .

The time interval during which the fast tracking change of the reference level is activated can be set constant or may depend on the type of change of operating modes, i.e. from its direction (switching from working on natural gas to working on gasoline or vice versa). The period of time during which the change of operating modes takes place and during which the fast tracking change of the reference level is activated, you can first of all choose such that the reference level reached at the end of the process of changing the operating modes reflects the changed background noise created by the engine. For this purpose, it is possible, for example, to envisage the end of a period of time during which a change of operating modes occurs after a certain predetermined period of time has elapsed, after which the transition to a gas mode of operation (in a second mode of operation) is completed.

In addition, a fast tracking change in the reference level can be initiated immediately upon completion of the natural gas operation mode (first operation mode) or at the moment when the share determined by the natural gas operation mode in the general operation mode of ICE 2 falls below a certain threshold.

In addition, in the process of changing the operating modes, it is possible to set the lead time of the ignition timing, which is intended to change the ignition timing to the later side, which helps to prevent the occurrence of knocking when the engine is in mixed mode. The lead value of the ignition timing corresponds to the amount of bias added to the calculated ignition timing. Due to this, the tendency of ICE to detonation is significantly reduced. In this way, an uninterrupted change of operating modes can be additionally ensured.

In addition, it is possible to initialize the lead of the ignition timing, depending on the temperature of the coolant and the temperature of the intake air.

On figa-3c shows the temporal characteristics of the signals, reflecting the nature of the change in lead ZV of the ignition timing when changing the operating mode on natural gas to the operating mode on gasoline.

When changing operating modes, the operating mode only on liquefied natural gas is first deactivated, which is indicated by a change in the level of the B_cng signal that characterizes this operating mode from high to low. At the end of the period of operation in mixed mode, the operation mode only on gasoline is activated, which is indicated by a change in the level characterizing this mode of operation of the signal B_bz in a similar way (see figv).

During operation in the mixed mode MB, i.e. during the period during which both signals B_cng and B_bz have a low level, by shifting the ignition moment ZZP, expressed in ° (degrees) of the angle of rotation of the crankshaft, adjust the lead ZV of the ignition timing and either immediately after operation in mixed mode (signal level B_bz changes to high), or after a certain time t_del, the lead value ZV of the ignition timing angle is smoothly or stepwise changed in the opposite direction, as a result of which, after resetting the magnitude of the lead timing of the ignition timing ICE 2 operates with an optimum ignition timing for the selected operating mode. The resulting transition curve can be coordinated with the operation parameters of the engine by the steepness of its rise and its duration, i.e. with its modes of operation.

The diagram in FIG. 3b shows the next change in the reference level rkr when the engine is in mixed mode. The shape of the curve K1 indicates, for example, a fast tracking change in the reference level, while the shape of the curve K2 reflects a change in the reference level, which usually occurs without changing the characteristics of low-pass filtering.

Claims (7)

1. A method for recognizing a detonation knock when changing operating modes of an internal combustion engine (2) of an internal combustion engine (ICE) in the first and second types of fuel, which consists in registering a signal characteristic (ikr) characterizing the body noise of an internal combustion engine (2), depending on the characteristic the signal characterizing the case noise (ikr) determines its reference level (rkr), corresponding to the parameters of the background noise generated by the engine, and depending on the reference level (rkr), the fact of the appearance of a detonation knock is established, characterized in that for definiteness reference level (rkr) characterizing the structure-borne noise signal (rkr) it is subjected to filtering in the low pass filter by a factor (TPF) low-pass filtering, which is selected for the time interval in which there is a change of operating modes, of lesser magnitude than outside it. 2. The method according to claim 1, in the implementation of which the fact of the appearance of a knock is established depending on the threshold value (SW), which is agreed upon during the change of the operating modes of the internal combustion engine on the first and second types of fuel. 3. The method according to claim 1, in the implementation of which, in the process of changing the operating modes, the ignition timing is set to change the actual ignition timing set for the internal combustion engine (2) to be later, and after a certain period of time, the magnitude of such angle ignition lead smoothly or stepwise reduce. 4. The method according to claim 3, in the implementation of which the lead time of the ignition timing is set depending on the temperature of the engine coolant (2) and / or the temperature of the intake air. 5. The method according to one of claims 1 to 4, in which the characteristic of the signal characterizing the case noise is recorded only at those time intervals during which detonation knocks may occur in the internal combustion engine (2). 6. A device for recognizing a knock when changing operating modes of an internal combustion engine (2) internal combustion engine on the first and second types of fuel, having a body noise registration unit (5) for recording a signal characteristic (ikr) characterizing body noise in an internal combustion engine (2), and a knock recognition unit (4) for detecting detonation knock signals (ikr), to determine its reference level (rkr), which corresponds to the parameters of the background generated by the engine noise, depending on the characteristics of this signal characterizing the case noise (ikr) and to establish the occurrence of a knocking depending on the reference level (rkr), characterized in that the detonation knock recognition unit (4) for determining the reference level (rkr) characterizing the case the noise of the signal (rkr) is configured to filter it in a low-pass filter using a low-pass filter coefficient (TPF), which is selected for the period of time during which the operating mode changes you are smaller than outside of it. 7. A motor system having an internal combustion engine (2) and a device according to claim 6.

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