KR20160065543A - Engine Combustion Noise Feedback Control Method based Estimation of Engine Vibration Signal - Google Patents

Abstract

The present invention relates to an engine combustion noise feedback control method based on estimation of an engine vibration signal. According to an engine combustion noise feedback control method based on estimation of an engine vibration signal, an engine combustion noise estimation value following a predetermined engine combustion noise target value is estimated by an engine vibration signal to be continuously changed. Thus, the engine combustion noise estimation value with respect to the engine combustion noise target value can accurately follow the engine combustion noise target value with feedback control changed by a first, second, and n_th engine combustion noise estimation value, and more specifically, a high-priced combustion pressure sensor to detect combustion pressure needs not to be used.

Description

[0001] The present invention relates to an engine vibration signal,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to engine combustion noise control, and more particularly to a method of controlling combustion noise feedback predicted by an engine vibration signal.

In general, combustion control that satisfies the combustion stability control (stable combustion and combustion noise control) aspects of the engine is very important even in disturbance conditions such as environment, fuel difference, and engine aging. This is more important in engines with high compression ratios (eg diesel engines).

As an example of such engine combustion control, there is a method of using the in-cylinder combustion pressure during engine driving. To this end, in the engine control system, a combustion pressure sensor installed in a cylinder constituting a combustion chamber is linked.

For example, when the engine is driven, the engine speed, the engine load, and the crank angle are checked from the engine, and the combustion pressure sensor directly detects the combustion pressure of the cylinder in the cylinder in accordance with the crank angle. Then, the pressure detection value of the combustion pressure sensor is applied to the determination of the MFB50 (mass fraction burned 50%) in which the heat release rate due to the combustion pressure is 50%, thereby determining the crank angle at which the MFB50 is obtained . Next, the point of the MFB 50 is calculated according to the operation state of the engine, defined as the measurement MFB 50, and then the measurement MFB 50 is compared with the target MFB 50, and the MFB 50 correction value (target MFB 50 - measurement MFB 50) is calculated. Then, the main injection timing is controlled by applying the MFB50 correction value calculated in the main injection timing control of the fuel.

As described above, the MFB50 is calculated by the combustion pressure of the combustion pressure sensor and the crank angle of the crank angle sensor during the engine operation, and then the calculated MFB50 is used to control the maximum pressure generation timing of the cylinder. Difference, and engine aging (engine aging).

U.S. Published Patent Application 2004-0050363 (2004, 03, 18)

However, the combustion pressure is used to determine the MFB50 (mass fraction burned 50%), and the combustion pressure sensor is used to detect the combustion pressure.

This is because the side on which the high-pressure combustion pressure sensor should be installed for each individual cylinder is the greatest cause, but the wire layout is also required so that the multiple-combustion pressure sensor is constructed as a system connected to each other.

Further, in the system using the combustion pressure detected by the combustion pressure sensor, it is inevitable that the pressure should be measured based on the crank angle in order to obtain the factor necessary for the control.

In view of the above, the present invention calculates an engine combustion noise estimation value based on a position of a maximum heat release rate predicted from an engine vibration signal and a primary or secondary correlation of the engine combustion noise, The injector injection quantity is controlled by the fuel injection parameter under the condition that the estimated value is larger than the engine combustion noise target value, and the feedback of the estimated value of the engine combustion noise is repeatedly performed to improve the accuracy of the engine combustion noise target value tracking. Which is predicted by an engine vibration signal which does not require the use of a high-pressure combustion pressure sensor.

In order to achieve the above-mentioned object, the present invention provides a method for estimating an engine noise level by an engine vibration signal, the method comprising: (A) setting an engine combustion noise target value of an engine in which an engine ECU is in operation; Compare it with the annual noise estimate; (B) detecting an engine vibration signal according to the combustion of the engine after changing the injection parameter of the injector to the engine if the engine combustion noise estimation value is larger than the engine combustion noise target value, Calculating a new engine combustion noise estimate by correlating the maximum heat release rate occurrence position with engine combustion noise after obtaining a maximum heat release rate; (C) if the new engine combustion noise estimate value is greater than the engine combustion noise target value, a new engine vibration signal is detected after changing the injection parameter to obtain a new maximum heat release rate, A feedback procedure is repeated in which a new engine combustion noise estimation value is calculated again with a correlation between an occurrence rate occurrence position and an engine combustion noise value and is compared with the engine combustion noise target value and the feedback procedure is repeated until the engine combustion noise target value and the engine combustion noise estimation value And stops when there is no difference.

The engine combustion noise target value is set for each engine fuel amount and engine RPM. In order to set the engine combustion noise target value, the engine ECU checks the amount of fuel, the engine RPM, the gear stage, the intake air temperature, and the cooling water temperature.

One or both of the main injection timing and the pilot injection amount are applied to the injection parameters of the injector.

(B-1) converting the engine vibration signal to a specific frequency band, (b-2) converting the value of the converted specific frequency band to an absolute value, (B-3) selecting a plurality of local peaks from the average target frequency pattern, comparing the sizes of selected local peaks, and comparing the local peaks with the largest difference to the maximum peak positions The heat generation rate occurrence position is calculated.

The correlation relationship is ^{y = (-0.0247x 2) + (} 0.942x) is represented by +69.069, x is a maximum heat generation rate occurs where, y is an engine, open noise estimate.

In the present invention, since the acquisition of the maximum heat release rate (MHRR) for controlling the engine combustion noise is performed by an acceleration sensor for detecting the engine vibration, engine combustion noise control can be performed without using an expensive combustion pressure sensor have.

Further, since a low-cost acceleration sensor is used in comparison with a high-pressure combustion pressure sensor, the engine system for controlling the noise can be constructed at low cost.

The present invention also provides a method of estimating the engine combustion noise by calculating an engine combustion noise estimate of a position of a maximum heat release rate (MHRR) predicted from an engine vibration signal, ) / Pmax (Maximum Cylinder Pressure) can be used in addition to the control method using the acceleration sensor.

FIG. 2 is an example of an engine combustion noise target value applied to the combustion noise feedback control method predicted by the engine vibration signal according to the present invention, and FIG. FIG. 3 is a flowchart for predicting the maximum heat generation rate with the engine vibration signal according to the present invention, and FIG. 4 is an example in which the estimated engine combustion noise is calculated from the maximum heat generation rate according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which illustrate exemplary embodiments of the present invention. The present invention is not limited to these embodiments.

FIG. 1 shows a flowchart of a method of estimating an engine noise vibration signal according to an embodiment of the present invention.

As shown in the figure, the combustion noise feedback control method predicted by the engine vibration signal is implemented by an engine ECU (Electronic Control Unit) 10, and the fuel injection amount of the injector 30 is controlled by the feedback control of the engine ECU 10, And the vibration signal corresponding to the operation of the engine 30 is detected by the acceleration sensor 40. [

Therefore, the combustion noise feedback control method predicted by the engine vibration signal, which will be described below, is implemented in the engine ECU 10, and particularly the engine ECU 10 is provided with a maximum heat release rate (MHRR) , The FBB50 target value / Pmax target value, and the first order correlation between MHRR and engine combustion noise are embedded in the map or logic.

Specifically, S10 is a step in which the engine ECU 10 sets the engine combustion noise target value for each engine fuel amount and engine RPM. To this end, the data read by the engine ECU 10 includes the amount of fuel, the engine RPM, the gear stage, the intake air temperature, the cooling water temperature, and the like, and may include the injection parameter if necessary. An example of setting the engine combustion noise target value is illustrated in FIG. As shown in the figure, engine load (unit bar) is divided into full load regions by engine RPM, and these values are measured through engine test and stored as data or maps. As an example, the engine combustion noise target value is set at 1500 RPM and about 76 at 5 bar.

S20 is a step of comparing the engine combustion noise target value with the engine combustion noise estimation value of the engine in operation. It is judged whether or not the estimated value of the engine soft noise is larger than the engine soft noise target value. In this case, the engine combustion noise estimation value is defined as the first engine combustion noise estimation value.

Equation: engine combustion noise estimate> engine combustion noise target value

Here, ">" indicates that the two values are large and small.

If the first engine combustion noise estimation value is not larger than the engine combustion noise target value in S20, combustion is performed in the engine 30 by entering S30. At this time, the fuel injection amount of the injector 20 injecting the fuel into the engine 30 is controlled so as to follow the engine combustion noise target value. On the other hand, if the first engine combustion noise estimate value is larger than the engine combustion noise target value in S20, the fuel injection quantity of the injector 20 following the engine combustion noise target value is changed in accordance with the first engine combustion noise estimation value by entering S70 . In this case, the injection variable control is the main injection timing and / or the pilot injection amount.

Next, the engine ECU 10 calculates the vibration detection of the engine 30 in S40, the MHRR generation position in S50, the engine combustion noise estimation value based on the MHRR generation position-engine combustion noise correlation in S60, And compared with the engine combustion noise target value. In this case, the engine combustion noise estimation value is defined as a second engine combustion noise estimation value.

Specifically, the MHRR generation position calculation of S50 is illustrated in FIG. S51 is a raw vibration signal received by the engine ECU 10. The engine vibration signal is detected by the engine ECU 10 in S40 detected by the acceleration sensor provided in the engine 30 and transmitted It is a vibration signal. Then, the engine ECU 10 converts the engine vibration signal (Raw Vibration Signal) into a specific frequency band (for example, 0.3 to 0.8 kHz) as in S51, accumulates values for the specific frequency band converted as in S52 And obtains an Average Target Frequency Pattern (ATFP) having a maximum peak by switching to an absolute value. At this time, ATFP acquisition is a wavelet transform applied to a signal processing technology for decomposing a signal into different frequency partial regions. However, in some cases, a simple transform using a filter can also be applied. Also, in the accumulation method for a specific frequency band in which absolute value conversion is performed, a method of reading and accumulating numerical values at intervals of 100 Hz based on the same time (time) is applied. Next, the engine ECU 10 selects a plurality of local peaks from the ATFP as in S53, S54, and S55, compares the sizes of the selected local peaks, and then calculates the local peaks (local peak) to the maximum peak position. In this case, the MPP in which the maximum peak position is selected from local peaks may be calculated by reading the values at intervals of 100 Hz based on the same time (time). As a result, the engine ECU 10 completes the MHRR generation position calculation as in S56.

Specifically, calculation of engine combustion noise estimation value by MHRR generation position-engine combustion noise correlation of S60 is illustrated in FIG.

As shown, in the HRR-crank angle diagram, it can be seen that when the operating conditions of the engine 30 are 1500 RPM and 5 bars, the MHRR occurrence position is at a crank angle of 13 degrees, and in the engine combustion noise- It can be seen that the engine combustion noise and MHRR generation position are expressed by the mathematical expression.

^{Equation: y = (-0.0247x 2) +} (0.942x) +69.069, where x is a maximum heat generation rate occurs where, y is an engine, open noise estimate. In this ^{case, y = (-0.0247x 2) +} (0.942x) +69.069 may be expressed by a primary expression bangbeong as follows. Equation: y = Ax + B, where A and B are coefficient values, respectively.

Therefore, by substituting x = 13 into the above equation, the engine combustion noise estimation value y = 77.1 is calculated. This engine combustion noise estimate value 77.1 is greater than the engine combustion noise target value 76 set at 1500 RPM and 5 bars when referring to FIG. Therefore, the engine ECU 10 defines the engine combustion noise estimation value 77.1 as the second engine combustion noise estimation value in S20, compares the second engine combustion noise estimation value with the engine combustion noise target value and confirms that it is a large value, and then proceeds to S70 And changes the fuel injection amount of the injector 20 in accordance with the second engine combustion noise estimation value. In this case, the injection variable control is the main injection timing and / or the pilot injection amount.

As described above, in the combustion noise feedback control method predicted by the engine vibration signal according to the present embodiment, the combustion noise feedback control method predicted by the engine vibration signal determines that the engine combustion noise estimation value following the set engine combustion noise target value is the engine vibration As the signal is predicted and changed continuously, the accuracy of the engine combustion noise target value follow-up is achieved by the feedback control in which the engine combustion noise estimate value is changed to the first, second, ... n engine combustion noise estimation value with respect to the engine combustion noise target value, In particular, the use of a high-pressure combustion pressure sensor for detecting combustion pressure is unnecessary.

10: Engine ECU (Electronic Control Unit)
20: injector 30: engine
40: Accelerometer

Claims (6)

(A) setting an engine combustion noise target value of an engine in which an engine ECU is operating, comparing the engine combustion noise target value with an engine combustion noise estimate;
(B) detecting an engine vibration signal according to the combustion of the engine after changing the injection parameter of the injector to the engine if the engine combustion noise estimation value is larger than the engine combustion noise target value, Calculating a new engine combustion noise estimate by correlating the maximum heat release rate occurrence position with engine combustion noise after obtaining a maximum heat release rate;
(C) if the new engine combustion noise estimate value is greater than the engine combustion noise target value, a new engine vibration signal is detected after changing the injection parameter to obtain a new maximum heat release rate, A feedback procedure is repeated in which a new engine combustion noise estimation value is calculated again with a correlation between an occurrence rate occurrence position and an engine combustion noise value and is compared with the engine combustion noise target value and the feedback procedure is repeated until the engine combustion noise target value and the engine combustion noise estimation value And stopping when there is no difference.
2. The method as claimed in claim 1, wherein in (A), the engine combustion noise target value is set for each engine fuel amount and engine RPM.
The method according to claim 2, wherein the engine ECU checks the amount of fuel, the engine RPM, the number of gears, the intake air temperature, and the cooling water temperature for the engine combustion noise target value setting.
The method according to claim 1, wherein the injection parameter of the injector is one of a main injection timing and a pilot injection amount, or both of them are applied.
The method of claim 1, wherein the new engine combustion noise estimate value is calculated by (b-1) converting the engine vibration signal to a specific frequency band, (b-2) (B-3) selecting a plurality of local peaks from the average target frequency pattern, comparing sizes of the selected local peaks, and obtaining the largest difference Wherein the maximum heat generation rate generating position is calculated to a maximum peak position at which a local peak is generated. The method according to claim 1, wherein in the (B), the correlation relationship is ^{y = (-0.0247x 2) + (} 0.942x) is represented by +69.069, x is generating maximum heat release rate location, y is the engine soft noise estimate Wherein the engine vibration signal is predicted as an engine vibration signal.

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