JP3708574B2 - Filtering method of differential value of intake and intake pressure - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electronically controlled fuel injection device that detects an intake air pressure to an internal combustion engine such as a vehicle engine to estimate an intake air amount and electronically controls a fuel injection amount, and differentiates a detected value of the intake air pressure. The present invention relates to a method for estimating an air amount with a small error by removing a noise component included in a detection value by performing a filtering process.
[0002]
[Prior art]
As a method for detecting the intake air pressure in the fuel injection electronic control for controlling the air-fuel ratio optimally satisfying the output of the vehicle engine, fuel economy, and exhaust gas countermeasures, an intake pipe pressure (PM) is provided by a sensor provided in the engine intake pipe. ) Was detected by Bosch in 1967, and the air-fuel ratio control that can improve engine torque characteristics and reduce harmful components of exhaust gas It has been adopted as a highly accurate method.
[0003]
The accuracy of the air-fuel ratio control is related to the accuracy of the measured value of the intake pipe pressure detected to estimate the intake air amount, but the pulsating ripple noise generated with the rotation of the engine included in this measured value. In addition, it is necessary to remove noise that interferes with various other controls.
[0004]
In the prior art, various devices have been devised for improving the air-fuel ratio control accuracy. For example, as disclosed in Japanese Patent Laid-Open No. 6-14695, pressure measuring means in a combustion chamber of an engine and noise removing means for the pressure measurement value To improve the fuel supply control method.
[0005]
In addition, generally, the detection value of the PM sensor is A / D-converted with a short period of, for example, 2/1000 seconds, and is 1 / m in order to remove noise superimposed on the PM sensor value. Better control (m = 8 in the current example) is performed. That is, when the current value of the PM sensor detection value is PMn and the value 2/1000 seconds ago is PMn-1, PMn = PMn + (PMn-PMn-1) / 8.
As removed.
[0006]
[Problems to be solved by the invention]
However, the removal of pressure measurement value noise by the fuel supply control method disclosed in Japanese Patent Laid-Open No. Hei 6-14695 smoothes the change in two or more in-cylinder pressure measurement values within a predetermined period during the compression process of the engine. Therefore, it is not possible to grasp and remove the pulsation accompanying the rotation of the engine, which is the main noise, and an optimal effect cannot be expected for engine control that requires delicate adjustment of the air-fuel ratio.
[0007]
In addition, when the 1 / m annealing control described above is performed, increasing the annealing (increasing m) increases the noise removal effect, but the response to changes in the intake air pressure value decreases, Conversely, if the annealing is made small (m is made small), the responsiveness increases, but the noise removal effect decreases.
[0008]
The object of the present invention is to solve the current situation as described above and to apply a filtering process to the differential value of the intake air pressure value in order to cope with a change in the vehicle state in order to cope with a transition due to a change in the vehicle state. An object of the present invention is to provide a method for filtering a differential value of intake air intake pressure, which can estimate an intake air amount with little error.
[0009]
[Means for Solving the Problems]
The present invention relates to a method for filtering a differential value dPM of a detected value PM of an intake air pressure in order to estimate an intake air amount to a vehicle engine and perform electronic control of a fuel injection amount.
Detects intake air pressure at a predetermined sampling cycle,
Calculate the amount of change in the detected value PM of the intake air pressure during the unit sampling period as a differential value,
Set an upper limit based on the maximum absolute value of the differential value for each pulsation cycle,
A method for filtering a differential value of intake air intake pressure, wherein the differential value of the next pulsation period is corrected to be deleted from the absolute value of the preceding pulsation period to the upper limit value and is derived as a differential value dPM. It is.
Further, the present invention is characterized in that the upper limit value is updated to the maximum value when the absolute value of the differential value for each pulsation period is not larger than a predetermined constant α.
Further, the present invention is characterized in that the upper limit value is not deleted when the modified differential value dPM is larger than a value obtained by multiplying the upper limit value by a predetermined coefficient β.
Further, the present invention detects a difference in the detected value PM of the intake air pressure during one rotation of the crankshaft of the vehicle engine,
The detected difference is compared with the derived differential value dPM, and when the difference is larger, the difference is derived as the differential value dPM.
[0010]
[Action]
According to the present invention, in order to estimate the intake air amount to the engine of the vehicle and to electronically control the fuel injection amount based on the estimation, the intake air pressure value PM to the engine is differentiated and the differential value is filtered. Processing.
[0011]
The intake air pressure value PM is detected at each predetermined short sampling period, the amount of change between the sampling periods of the A / D converted detection value PM is calculated as a differential value, and each pulsation of the calculated differential value is calculated. For each period, the maximum absolute value of the differential value is set as the upper limit value. When the absolute value of the differential value calculated in the next pulsation cycle is larger than the upper limit value of the preceding cycle, the value is corrected to a value obtained by subtracting the upper limit value from the absolute value of the differential value. It is corrected to 0 and derived as a differential value dPM. As a result, the pulsation of the differential value dPM value is removed.
[0012]
Further, according to the present invention, when the maximum absolute value of the differential value for each pulsation period is not larger than a value obtained by adding a predetermined constant α to the upper limit value, the upper limit value is updated to the maximum value. If it is larger, it is updated to a value obtained by adding α to the upper limit value. As a result, a limit is set to the upper limit value, and the differential value dPM value is corrected based on the upper limit value. Therefore, it is possible to prevent an error in removing changes other than pulsation.
[0013]
Further, according to the present invention, when the value of the modified differential value dPM is larger than a value obtained by multiplying the predetermined constant β by the upper limit value, the subtracted upper limit value is added again to obtain the differential value dPM value. As derived. Accordingly, when a value that is β times the upper limit value is detected in the value obtained by removing the upper limit value, the change is other than pulsation, and it can be determined that the change is due to a change in the vehicle state, and the removal can be canceled.
[0014]
Further, according to the present invention, the difference in the intake air pressure value PM during one revolution of the crankshaft of the vehicle engine is detected, and the detected difference is compared with the derived differential value dPM, and the larger one is determined as the differential value dPM. The decision value. As a result, in all of the cases described above, the process emphasizes responsiveness to changes, but by detecting a value that is not easily affected by the pulsation, a gentle PM change smaller than the change detected from the pulsation is detected. The amount of air can be estimated.
[0015]
【Example】
FIG. 1 is a configuration diagram of a system that electronically controls fuel injection to a vehicle engine to which an embodiment of the present invention is applied. An intake pressure of the air 2 sucked into the engine 1 is detected by a PM sensor 3 which is an intake air pressure detection sensor, and the detected value is detected by an A / D converter 5 constituting an electronic fuel injection control device 4 called an EFi computer. A / D conversion is performed, and this is converted into a PM value and taken into a PM filter 6 which is an intake air pressure filter constituting the control device 4 and processed. The air amount estimation processing unit 7 constituting the control device 4 estimates the intake air amount to the engine based on the processing result of the PM filter 6 according to the present invention, and also configures the control device 4 based on the estimated air amount. The fuel amount calculation unit 8 calculates the amount of fuel injected into the engine. The injector valve opening controller 9 constituting the control device 4 controls the injector 10 which is a fuel injector based on the calculated value of the fuel amount, and injects the calculated amount of fuel 11. The fuel 11 injected into the engine 1 is mixed with the intake air 2, and the mixed gas 12 is compressed and ignited in the engine 1 to explode.
[0016]
FIG. 2 shows an embodiment of the present invention in which an intake air pressure to an engine is detected by a PM sensor sampling every 2/1000 seconds, that is, every 2 mS, and the detected value is A / D converted by an A / D converter. An operation in which the PM filter performs arithmetic processing on the obtained PM data is shown. In step 101, PMn-1 which is the PM value inputted 2mS before, that is, the PM value inputted last time is subtracted from PMn which is the current PM value, and the change amount of PM data between 2mS is calculated as a differential value dPM. The absolute value | dPMn | of dPM calculated in step 102 is compared with the maximum value (maxdPM) of dPM during the current PM pulsation period stored in the memory for calculation. If | dPMn | The process proceeds to 103, and the maximum value (maxdPM) of the memory for calculation is updated to the current absolute value of dPM | dPMn |, and the process proceeds to step 104. If | dPMn | Without proceeding to step 104. In step 104, it is determined whether or not the sign of the calculated differential value dPMn is inverted with respect to the previous input. When the sign is inverted, the process proceeds to step 105, where it is considered that the pulsation has been exceeded and is the upper limit value in the pulsation cycle. Set (maxdPM) to the maximum value maxdPMk of the latest pulsation cycle, and proceed to Step 106. In step 106, (maxdPM) of the calculation memory is cleared to 0, and the process proceeds to step 107. If the sign of dPMn is not inverted at step 104, the routine proceeds to step 108, where the maximum value of the pulsation period maxdPMk is not updated, and the maximum value of the previous pulsation period, maxdPMk-1, remains unchanged and the routine proceeds to step 107. . In step 107, it is determined whether or not | dPMn | which is the absolute value of the differential value of PM in the next pulsation cycle is larger than the maximum value maxdPMk of the preceding cycle. If not, the routine proceeds to step 109, where | dPMn | If the value is larger than 0, the process proceeds to step 110, and a value obtained by deleting maxdPMk from | dPMn | is derived as a modified differential value. 2 is a symbol for explanation to be described later.
[0017]
FIG. 3 shows the operation of the embodiment in which a limit is set on the upper limit value during the pulsation period set in the operation of FIG. Steps 201 to 204 are exactly the same as steps 101 to 104 in FIG. 2, and steps 205 and 206 are the same as steps 108 and 107 in FIG. In step 207, it is determined whether or not the upper limit value (maxdPM) set in step 203 is smaller than a value obtained by adding a preset value α to the maximum value maxdPMk−1 of the previous pulsation cycle. The maximum value of the pulsation cycle maxdPMk is set to a value obtained by adding α to the maximum value of the previous pulsation cycle maxdPMk-1, and if it is smaller, the process proceeds to step 209 as in FIG. 2, and the upper limit value in the pulsation cycle is reached. Let (maxdPM) be the maximum value maxdPMk of the latest pulsation cycle. In step 210, the calculation memory is cleared in the same manner as in step 106 of FIG. 2, and then the routine proceeds to step 206, where is the absolute value of the differential value in the next cycle | dPMn | is greater than the maximum value maxdPMk of the preceding cycle? If it is not larger, the process proceeds to step 211 where | dPMn | is set to 0. If it is larger, the value obtained by deleting maxdPMk from | dPMn | is derived as a modified differential value in step 212. In addition, (1) mark of the lower part of FIG. 3 is also a symbol for the following description.
[0018]
FIG. 4 shows the operation of the embodiment adopted as a countermeasure when the fluctuation of the detected value is much larger than the pulsation width, and steps 301 to 311 are exactly the same as steps 201 to 211 of FIG. In step 313, the maximum value maxdPMk of the preceding period is deleted from | dPMn | which is the absolute value of the differential value in the cycle as in step 212 of FIG. If the value is larger than the value obtained by multiplying the upper limit by a preset value, β is derived by adding again the maximum value maxdPMk of the preceding period deleted in step 313 in step 314. In addition, (1) mark of the lower part of FIG. 4 is also a symbol for the below-mentioned description.
[0019]
FIG. 5 shows the operation of an embodiment in which a gradual change is detected and controlled. In step 401, sampling is performed every rotation of the crankshaft of the engine, that is, every 360 degrees, the difference between the detected values is set to dPMm, and the process proceeds to step 402 together with the output indicated by the symbol at the bottom of FIGS. The absolute value of the difference is compared with | dPMn | derived in any of the cases of FIGS. 2 to 4 at 402, and when the difference of one rotation is larger, dPMm is adopted as dPM at step 403, If not, dPMn is adopted in step 404, and dPM is determined in step 405.
[0020]
【The invention's effect】
As described above, according to the present invention, every time the detected value PM of the intake air pressure detected at each sampling cycle is detected, the difference from the previous detected value is calculated as a differential value. Further, the extreme value of the pulsation of the pulsating noise component accompanying the rotation of the engine included in the PM value is regarded as a conversion point of the sign of the differential value. The maximum value within the pulsation cycle of the absolute value of the differential value is detected as the pulsation cycle between the extreme values, and the upper limit value is detected every time the pulsation cycle is repeated. A value obtained by removing the minute is used as a modified value of the differential value dPM. By this process, noise mainly including the pulsation component is removed. In addition, the present invention sets a limit on the magnitude of the update of the upper limit value, and updates the upper limit value when a maximum value within the limit is detected, but does not update it to a value exceeding the limit. This process can prevent errors that remove changes other than pulsation.
[0021]
In the present invention, when the differential value dPM after correction by subtracting the upper limit value is larger than the value obtained by multiplying the upper limit value by a predetermined number, a process for canceling the correction is performed. This can be dealt with as a change in the vehicle state.
[0022]
Further, according to the present invention, the intake air pressure is detected every 360 degrees of rotation of the crankshaft, and the difference between the detected values is compared with the difference between the correction values, and the larger one is used as the determined value of the differential value dPM. Thus, it is possible to detect a gradual change in the differential value that is smaller than the change amount detected from the pulsation value.
[0023]
As described above, according to the present invention, dPM, which is a differential value of the intake air pressure value, is obtained, and the true air amount is estimated by performing a filter process to cope with the fuel injection control at the time of transition due to a change in the vehicle state. can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the relationship between an electronically controlled fuel injection system for a vehicle engine and an engine, air, fuel and fuel injector for implementing the present invention.
FIG. 2 is a flowchart showing an operation of an intake pressure filter process according to an embodiment of the present invention.
FIG. 3 is a flowchart showing an operation of intake pressure filter processing according to another embodiment of the present invention.
FIG. 4 is a flowchart showing an operation of intake pressure filter processing according to still another embodiment of the present invention.
FIG. 5 is a flowchart showing an operation of intake pressure filter processing according to still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vehicle engine 2 Air which engine takes in 3 Air pressure detection sensor 4 Electronic fuel injection system 5 A / D converter 6 Intake pressure filter 7 Air quantity estimation processing part 8 Fuel quantity calculation part 9 Injector valve opening control part 10 Injector 11 Fuel 12 Mixed gas dPM differential value of air and fuel

Claims (4)

In a method for estimating an intake air amount to a vehicle engine and filtering a differential value dPM of a detected value PM of an intake air pressure in order to perform electronic control of a fuel injection amount,
Detects intake air pressure at a predetermined sampling cycle,
Calculate the amount of change in the detected value PM of the intake air pressure during the unit sampling period as a differential value,
Set an upper limit based on the maximum absolute value of the differential value for each pulsation cycle,
A method for filtering a differential value of intake air intake pressure, wherein the differential value of the next pulsation period is corrected to be deleted from the absolute value of the preceding pulsation period to the upper limit value and is derived as a differential value dPM. .   2. The inhalation and intake air according to claim 1, wherein the upper limit value is updated to the maximum value when the absolute value of the differential value for each pulsation cycle is not greater than a predetermined constant α. Filtering method for differential pressure value.   3. The intake air intake pressure according to claim 1, wherein when the modified differential value dPM is greater than a value obtained by multiplying the upper limit value by a predetermined coefficient β, the upper limit value is not deleted. Differential value filtering method. Detecting a difference in the detected value PM of the intake air pressure during one rotation of the crankshaft of the vehicle engine;
4. The intake and intake air according to claim 1, wherein the detected difference is compared with the derived differential value dPM, and when the difference is larger, the difference is derived as the differential value dPM. Filtering method for differential pressure value.

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