JPH08177581A - Intake pressure filter processing method - Google Patents

Abstract

PURPOSE: To enable the estimation of the intake quantity by filter processing the intake pressure detection value of an engine. CONSTITUTION: The detection value of intake pressure every 2mS is differentiated (101), the maximum value in the pulsation cycle of the differential value is made the upper limit value (102-105), and pulsation is eliminated by deducting the value up to the limit value from the differential value in the following pulsation cycle (109, 110) so as to attain the responsiveness of control. This prevents elimination other than pulsation by providing the upper limit value with other limits and cancels an eliminating process to the large change of the detection value caused by the change of state. The moderate change is obtained by the detection value every rotation of a crankshaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for detecting the intake air pressure to an internal combustion engine such as a vehicle engine to estimate the intake air amount and electronically controlling the fuel injection amount. The present invention relates to a method of estimating the air amount having a small error by removing the noise component included in the detected value by differentiating the detected value of 1. and filtering.

[0002]

2. Description of the Related Art A sensor installed in an intake pipe of an engine is used as a method for detecting intake air pressure in electronic fuel injection control for controlling an optimum air-fuel ratio that satisfies output of a vehicle engine, fuel economy and measures for exhaust gas. The D-Jetronic method, which detects the intake pipe pressure (PM) and estimates the intake air amount from the PM value, was announced by Bosch in 1967 to improve the torque characteristics of the engine and reduce harmful components of exhaust gas. It has been adopted as a method with good air-fuel ratio control accuracy.

The accuracy of the air-fuel ratio control depends on the accuracy of the measured value of the intake pipe pressure detected for estimating the intake air amount, but the pulsatility generated by the rotation of the engine included in this measured value. It is necessary to remove the ripple noise of the noise and other noises that interfere with various controls.

In the prior art, various measures have been taken to improve the accuracy of air-fuel ratio control.
As shown in 146995, an attempt is made to improve the fuel supply amount control method by providing a pressure measuring means in the combustion chamber of the engine and a noise removing means of the pressure measured value.

In general, the detected value of the PM sensor is generally subjected to A / D conversion arithmetic processing in a short cycle of, for example, 2/1000 seconds to remove noise superimposed on the PM sensor value. / M smoothing control (in the current example, there is m = 8). That is, when the current value of the PM sensor detection value is PMn and the value 2/1000 seconds before is PMn-1, PMn = PMn + (PMn-PMn-1) / 8 is removed.

[0006]

However, the noise removal of the pressure measurement value by the fuel supply control method of the above-mentioned Japanese Patent Laid-Open No. 6-146995 is performed by measuring two or more in-cylinder pressures within a predetermined period during the compression process of the engine. Since it is a method of smoothing the change in the value, it is not possible to grasp and remove the pulsation due to the rotation of the engine, which is the main noise, and it is expected to be the optimum effect for engine control that requires subtle adjustment of the air-fuel ratio Can not.

Further, in the case of performing the 1 / m smoothing control described above, if the smoothing is increased (m is increased), the noise removing effect is increased, but the responsiveness to changes in the intake air pressure value is increased. If the noise is reduced and conversely the noise is reduced (m is reduced), the responsiveness increases, but the noise removal effect decreases.

An object of the present invention is to solve the above-mentioned current situation and to cope with a transient state due to a change in vehicle state.
It is an object of the present invention to provide an intake air pressure filtering method capable of adding a filtering process to a differential value of an intake air pressure value to cope with a change in a vehicle state and estimating an intake air amount with a small error.

[0009]

SUMMARY OF THE INVENTION The present invention is a method for estimating the intake air amount to an engine of a vehicle and filtering a differential value dPM of a detected intake air pressure value PM for electronically controlling a fuel injection amount. In, the intake air pressure is detected at a predetermined sampling cycle, and the change amount of the detected value PM of the intake air pressure between unit sampling cycles is calculated as a differential value,
Set the upper limit value based on the maximum value of the absolute value of the differential value for each pulsation cycle, amended to delete the upper limit value of the preceding pulsation cycle from the absolute value of the differential value of the next pulsation cycle,
The intake air pressure filtering method is characterized by deriving as a differential value dPM. 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 cycle is not larger than a predetermined constant α by a predetermined constant α or more. Further, according to the present invention, the modified differential value dPM is a coefficient β that predetermines the upper limit value.
When it is larger than the value multiplied by, the deletion of the upper limit value is not performed. Further, according to the present invention, the difference in the detected value PM of the intake air pressure during one revolution of the crankshaft of the vehicle engine is detected, the detected difference is compared with the derived differential value dPM, and the difference is larger. In this case, the difference is derived as a differential value dPM.

[0010]

According to the present invention, the intake air amount to the engine of the vehicle is estimated, and the intake air pressure value PM to the engine is differentiated in order to electronically control the fuel injection amount based on the estimation. You are filtering the values.

The intake air pressure value PM is detected for each predetermined short sampling period, the change amount of the A / D converted detection value PM between the sampling periods is calculated as a differential value, and the calculated differential value is calculated. For each cycle of pulsation, the maximum absolute value of the differential value is set as the upper limit value. If the absolute value of the differential value to be calculated in the next pulsation cycle is larger than the upper limit value of the preceding cycle, correct the value by subtracting the upper limit value from the absolute value of the differential value. It is corrected to 0 and is derived as the differential value dPM. As a result, the pulsation of the differential value dPM value is removed.

According to the present invention, when the maximum absolute value of the differential value for each pulsation cycle is not larger than the value obtained by adding a predetermined constant α to the upper limit value, the upper limit value is set to the maximum value. The value is updated, and when it is larger, it is updated to the value obtained by adding α to the upper limit value. As a result, a limit is set on the upper limit value, and the differential value dPM value is corrected by the upper limit value, so that an error of removing changes other than pulsation can be prevented.

Further, according to the present invention, when the value of the modified differential value dPM is larger than the value obtained by multiplying the upper limit value by a predetermined constant β, the subtracted upper limit value is added again to differentiate. The value is derived as the dPM value. In this way, 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 something other than pulsation, and the removal can be canceled by judging that it is due to a change in the vehicle state.

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 larger than the derived differential value dPM. It is the determined value of the differential value dPM. As a result, in any of the above-described cases, the process that attaches importance to the responsiveness to changes, whereas the detected value that is less susceptible to pulsation causes a slow P
It is possible to estimate the air amount by detecting the M change.

[0015]

1 is a block diagram of a system for electronically controlling fuel injection to an engine of a vehicle to which an embodiment of the present invention is applied. The intake pressure of the air 2 drawn 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 which constitutes an electronic fuel injection control device 4 called an EFi computer. A / D conversion is performed, the PM value is taken as a PM value, and the PM value is taken into a PM filter 6 which is an intake air pressure filter constituting the control device 4 and processed.
Based on the processing result of the PM filter 6 according to the present invention, the air amount estimation processing unit 7 constituting the control device 4 estimates the intake air amount to the engine, and also configures the control device 4 based on the estimated air amount value. The fuel amount calculation unit 8 calculates the amount of fuel injected into the engine. The injector valve opening controller 9 that constitutes the control device 4 controls the injector 10, which is a fuel injector, based on the calculated fuel amount, and injects the calculated amount of fuel 11. Fuel 1 injected into the engine 1
1 is mixed with intake air 2 and mixed gas 12 is mixed with engine 1
It is compressed inside, ignited and exploded.

In FIG. 2, in one embodiment of the present invention, the PM sensor samples and detects the intake air pressure to the engine every 2/1000 seconds, that is, every 2 mS, and the detected value is detected by an A / D converter. The operation in which the PM filter performs arithmetic processing on the PM data that has been D / D converted is shown. In step 101, the current PM value PMn is subtracted by 2 mS before, that is, the previously input PM value PMn-1 is calculated, and the change amount of PM data between 2 mS is calculated as a differential value dPM. Absolute value of dPM calculated in step 102 | dPM
n | is compared with the maximum value (maxdPM) of dPM during the pulsation cycle of the current PM stored in the memory for calculation, and | d
If PMn | is larger, the routine proceeds to step 103, where the maximum value (maxdPM) of the calculation memory is calculated and the current d
The absolute value of PM is updated to | dPMn | and the routine proceeds to step 104. If it is judged in step 102 that | dPMn | is not larger, the routine proceeds to step 104 without updating.
In step 104, it is determined whether the positive or negative sign of the calculated differential value dPMn is inverted with respect to the previous input. (MaxdP
Let M) be the maximum value maxdPMk of the latest pulsation cycle, and go 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 in step 104, the process proceeds to step 108 and the maximum value max of the pulsation cycle is max.
The dPMk is not updated, and the maximum value of the last pulsation cycle, that is, maxdPMk-1 is left as it is, and the routine proceeds to step 107.
In step 107, | dPMn |, which is the absolute value of the differential value of PM in the next pulsation cycle, is the maximum value maxdPMk of the preceding cycle.
It is judged whether or not it is larger than that. If it is not larger, step 109 is proceeded to, and | dPMn | is set to 0, and if it is larger, step 110 is proceeded to from | dPMn | to maxd.
A value obtained by deleting PMk is derived as a modified differential value.
Note that the mark at the bottom of FIG. 2 is a symbol for the description below.

FIG. 3 shows an operation of the embodiment in which an upper limit value in the pulsation cycle set in the operation of FIG. 2 is limited. Steps 201 to 204 are step 1 in FIG.
This is exactly the same as 01 to 104, and steps 205 and 20
Step 6 is the same as steps 108 and 107 in FIG. In step 207, the upper limit value (maxdPM) set in step 203 is the maximum value maxdP of the preceding pulsation cycle.
It is determined whether it is smaller than a value obtained by adding a preset value α to Mk-1, and if not smaller, the routine proceeds to step 208, where the maximum value pulsation cycle maxdPMk is set to the maximum value pulsation cycle maximum value maxdPMk-1 α. If it is smaller, the procedure proceeds to step 209 as in the case of FIG. 2 and the upper limit value (maxdPM) in the pulsation cycle is set to the maximum value max of the latest pulsation cycle.
Let dPMk. In step 210, step 1 in FIG.
After clearing the calculation memory similarly to 06, the routine proceeds to step 206, where | d which is the absolute value of the differential value in the next cycle.
It is determined whether PMn | is larger than the maximum value maxdPMk of the preceding cycle, and if it is not larger, step 211
Then, | dPMn | is set to 0, and if larger, the value obtained by deleting maxdPMk from | dPMn | in step 212 is derived as a modified differential value. The mark at the bottom of FIG. 3 is also a symbol for the description below.

FIG. 4 shows the operation of the embodiment adopted as a countermeasure when the fluctuation of the detected value is extremely large beyond the pulsation width. Steps 301 to 311 are steps 201 to 201 of FIG.
~ 211 is exactly the same. In step 313, as in step 212 of FIG. 2, the absolute value of the differential value in the cycle is |
After the maximum value maxdPMk of the preceding cycle is deleted from dPMn |, when the absolute value of the modified differential value determined in step 312 is larger than the value obtained by multiplying the upper limit value preset by β. Is derived by adding again the maximum value maxdPMk of the preceding cycle deleted in step 313 in step 314. The mark at the bottom of FIG. 4 is also a symbol for the description below.

FIG. 5 shows the operation of the embodiment for detecting and controlling the gradual change. In step 401, sampling is performed every one rotation of the crankshaft of the engine, that is, every 360 degrees, and the difference between the detected values is set to dPMm.
02, in step 402, the absolute value of the difference is compared with | dPMn | derived in any of the cases of FIGS. 2 to 4, and if the difference of one rotation is greater, step 403
In step 404, dPMm is adopted as dPMm. If not, dPMn is adopted in step 405.
Determine M.

[0020]

As described above, according to the present invention, the detected value PM of the intake air pressure detected at each sampling cycle is calculated as the differential value every time it is detected, from the previous detected value PM. 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 the conversion point of the positive / negative sign of the differential value. The maximum value in the pulsation cycle of the absolute value of the differential value is detected as the upper limit value with the interval between the extreme values as the pulsation cycle, and the upper limit value is changed from the derivative value of the next pulsation cycle while repeating the updating of the upper limit value for each pulsation cycle. The corrected value of the differential value dPM is obtained by removing the amount. By this processing, noise mainly composed of the pulsating component is removed. The present invention also sets a limit on the magnitude of updating the upper limit value and updates the upper limit value when a maximum value within the limit is detected, but does not update the value above the limit. By this processing, it is possible to prevent an error of removing changes other than pulsation.

Further, according to 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. You can go and react as if due to changes in vehicle conditions.

Further, according to the present invention, the intake air pressure is detected every 360 ° rotation of the crankshaft, the difference between the detected values and the difference between the correction values are compared, and the larger one is determined as the determined value of the differential value dPM. By doing so, it is possible to detect a gradual change in the differential value smaller than the change amount detected from the pulsation value.

As described above, according to the present invention, dPM which is the differential value of the intake air pressure value is obtained, and the true air amount is estimated by performing the filtering process to inject the fuel during the transition due to the change of the vehicle condition. Can respond to control.

[Brief description of 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 a fuel injector for carrying out the present invention.

FIG. 2 is a flowchart showing an operation of intake pressure filtering processing according to an embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of intake pressure filtering processing according to another embodiment of the present invention.

FIG. 4 is a flowchart showing an operation of intake pressure filtering processing according to still another embodiment of the present invention.

FIG. 5 is a flowchart showing an operation of intake pressure filtering processing according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Engine of Vehicle 2 Air Intaken by Engine 3 Air Pressure Detection Sensor 4 Electronic Fuel Injection System 5 A / D Converter 6 Intake Pressure Filter 7 Air Quantity Estimation Processing Section 8 Fuel Quantity Calculation Section 9 Injector Valve Control Section 10 Injector 11 Fuel 12 Mixed gas of air and fuel dPM Differential value

Claims (4)

[Claims] 1. A method for estimating a quantity of intake air into a vehicle engine and filtering a differential value dPM of a detected value PM of intake air pressure for electronically controlling a fuel injection quantity, wherein intake is performed at a predetermined sampling cycle. The air pressure is detected, the amount of change in the detected value PM of the intake air pressure between unit sampling cycles is calculated as a differential value, and the upper limit value based on the maximum absolute value of the differential value is set for each pulsation cycle. The absolute value of the differential value of the cycle is corrected so as to be deleted up to the upper limit value of the preceding pulsation cycle, and the differential value dP
An intake-intake-pressure filter method, characterized in that it is derived as M. 2. The upper limit value is updated to the maximum value when the absolute value of the differential value for each pulsation cycle is not larger than a predetermined constant α by a predetermined constant α or more. 1. The method for filtering intake and intake pressure according to 1. 3. When the modified differential value dPM is larger than a value obtained by multiplying the upper limit value by a predetermined coefficient β,
The intake / intake pressure filtering method according to claim 1, wherein the upper limit value is not deleted. 4. A difference in the detected value PM of the intake air pressure 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 difference is larger. The intake / intake pressure filtering method according to any one of claims 1 to 3, wherein the difference is derived as a differential value dPM.