JPH01271647A - Device for detecting intake air quantity of engine - Google Patents

Abstract

PURPOSE:To operate an intake air quantity with high accuracy by estimating the value of an intake air quantity during interruption control from the detected values of the intake air quantities immediately after and before the interruption control and calculating the average value in the interruption control prior to the average operating action of an intake air quantity. CONSTITUTION:An electronic control unit 9 reads the detected value of an air flow meter 2 at a defined period and operates the average value within the defined period to obtain a fuel injection quantity. In this case, as an interruption control prior to the operating action of an intake air quantity is optionally executed by a fuel-injection interruption routine 200, an intake-air quantity operation routine 300 is operated by an engine control main routine 100, and an intake air quantity detected value during the interruption control is estimated from an intake air quantity detected value immediately after the end of the interruption control and an intake air quantity detected value before the interruption control to the calculate the average value of the intake air quantity as a target. Thereby, the intake air quantity can be operated with high accuracy without reducing the original number of times of reading the intake air quantity because of the execution of the interruption control.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Use The present invention relates to an engine intake air amount detection device.

(Prior art) For example, in an electronically controlled fuel injection system that adopts a mass flow type, the fuel injection amount is determined according to the intake air amount measured by an intake air amount measuring device called an airflow meter. There is.

The measured value of the above-mentioned intake air amount measuring device is generally expressed in the form of an electrical signal such as a potential difference □ signal, and is read into the engine control unit for controlling the fuel injection amount at a predetermined periodic interrupt operation, and the average value is calculated as the above-mentioned average value. Used to calculate fuel injection amount.

By the way, in the engine control unit, for example, other subroutines (for example, fuel injection control) are performed in synchronization with the crank angle signal (1 pulse/chamber rotation) of the engine.
In such a case, the reading of the intake air amount measurement value will be delayed until the end of the subroutine. For this reason, under conditions where the intake pulsation of the intake system and the intake air amount measurement value match, it becomes impossible to obtain an accurate average value of the intake air amount, and the engine air-fuel ratio (A/F) There is a problem in which overlean and overridge conditions are becoming a concern.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and includes an intake air m detection means for detecting the intake air amount of an engine, and an intake air m detection means for detecting the intake air amount of an engine. an intake air amount calculation means which reads the detected values of at a predetermined period and calculates the average value within a predetermined period to obtain intake air m for fuel injection amount control; In an electronically controlled engine comprising an interrupt control means that performs interrupt control preferentially for reading operations of a predetermined period, a read value of the detected value of the intake air amount detection means immediately after the interrupt control of the interrupt control means ends; Predictive calculation means is provided for predicting and calculating the read detection value of the original detection cycle during the interrupt control of the interrupt control means based on the detection value of the same means read in the previous cycle.

(Function) In the configuration of the present invention described above, the detection value of the intake air claw detection means such as an air flow meter is read at a predetermined reading cycle and the average value within a predetermined period is calculated, thereby forming the basis of the fuel injection amount. It is designed to calculate the amount of intake air.

On the other hand, a predetermined interrupt control means is provided which gives priority to the calculation operation of the intake air amount, and the interrupt control which gives priority to the calculation operation of the intake air amount is arbitrarily executed. The calculation means operates to predict the intake air amount detected value during the interrupt control from the intake air amount detection value immediately after the interrupt control ends and the intake air amount detection value before the interrupt control, and calculates the desired intake. The average value of the air volume is calculated.

(Effects of the Invention) Therefore, according to the configuration of the present invention, the number of times the original intake air amount is read does not decrease due to execution of the interrupt control, and the predicted value itself is based on the most recent values before and after the interrupt control. Since it can be regarded as substantially equal to the actual measured value, the final calculated intake air m also has high accuracy.

(Example) First, FIGS. 1 to 3 show an embodiment of the air-fuel ratio control device during engine idling operation of the present invention, and FIG. 1 is a schematic diagram of the control system of the device according to the embodiment. ,
FIG. 2 is a basic circuit diagram of the same, and FIG. 3 is a flowchart showing intake air amount detection and air-fuel ratio control operations of the engine control unit in the same control system.

First, the outline of the control system according to the embodiment of the present invention will be explained with reference to FIG. 1, and then the control of the main parts will be explained.

In FIG. 1, reference numeral l is the engine body, and intake air is taken in from the outside via an air cleaner 30.
Thereafter, the air is supplied to each cylinder via an air flow meter 2 and a throttle chamber 3.

Further, fuel is supplied from the fuel tank 12 to the engine side by the fuel pump I3, and is injected by the fuel injector 5. The amount of air taken into the cylinder when the accelerator pedal is operated, such as when the vehicle is running, is controlled by a throttle valve 6 provided in the throttle chamber 3. The throttle valve is
When operated in conjunction with the accelerator pedal and in an idling state, the opening state is maintained at the minimum opening state. And the minimum (
Fully closed) In the open state, the idle switch swr.

turns on.

The throttle chamber 3 is provided with a bypass intake passage 7 that bypasses the throttle valve 6, and the bypass intake passage 7 serves as an intake air ffi adjusting means for controlling the engine speed during idling. A current-controlled solenoid valve Cl5C valve) 8 is provided. Therefore, in the idle operating state, the intake air that has passed through the air flow meter 2 is supplied to each cylinder via the bypass intake passage 7, and the amount of intake air supplied is adjusted by the solenoid valve 8. The opening/closing state (valve opening degree) of the solenoid valve 8 is controlled by the duty ratio of a solenoid valve control signal supplied from an engine control unit (hereinafter referred to as ECU 18) 9.

That is, in the case of idling operation, for example, as will be described later, an ECU 9 constituted by a microcomputer is used to constitute an electronic intake air amount control means, and the current-controlled solenoid valve 8, which is the intake air amount adjustment means, is activated. is controlled by a predetermined basic control ffi Ga set corresponding to a preset predetermined idle target rotation speed No, and the actual engine rotation speed NE obtained by the predetermined basic control amount GB is the set idle target. If it does not match the rotational speed No., the actual rotational speed NE is changed to the idle target set above by correcting the predetermined basic control amount Ga according to the rotational deviation amount ΔN [and the engine external load ff1EL, etc.] at that time. A configuration is adopted that allows the rotation speed to converge to NO.

In this case, the final solenoid valve control amount (final control amount) including the various correction amounts described above is generally determined as follows.

Final control amount G=Gn+ΣGL+GF8+GFB fist LRN
...(1) However, GB: Basic control amount GL: Load correction amount corresponding to various engine loads GF8: Feedback correction amount based on rotational deviation Q ra -LRN: Learning correction amount Here, the above basic control ff1GB is generally It is set in correspondence with the engine rotation speed and the cooling water temperature value based on characteristic values unique to the engine when the engine is under no load and without deterioration. The load correction 1iGL corresponding to every engine load (for example, air conditioner, power steering, etc.) is determined as a unique value according to each load amount EL, and acts as an intake air amount increase value. Furthermore, the feedback correction ff1GF8 is a correction amount during closed-loop control that is arbitrarily determined according to the operating state and according to the deviation amount between the actual engine speed and the target engine speed. Further, the learning correction IIGFB-LRN is a value calculated based on the average value of the feedback correction ff1GF8 within a predetermined sampling period under learning conditions, and is a value that is calculated based on the average value of the feedback correction ff1GF8 within a predetermined sampling period, and is used to correct aging changes in engine characteristics and to maintain the hunting limit. It acts as a positive hrI value for feedback control to improve control response and stability.

That is, as is clear from the above general formula (which is a formula for calculating the duty ratio of the control signal that drives and controls the solenoid of the solenoid valve 8, which is the intake air amount adjusting means described above), the final control fiG is as follows: Based on the basic control amount CB determined by the characteristic value unique to the engine and the cooling water temperature, a correction amount GL corresponding to the load amount, a feedback correction fitGFB% corresponding to the deviation amount of the rotation speed, and also based on the feedback correction ffi G F8. The learning control ff1GFB-LnN is calculated using the learning control ff1GFB-LnN. Furthermore, the reference numeral 1O indicates, for example, an exhaust pipe having a three-way catalytic converter (catalyst converter) 11 in the middle of the exhaust passage and having an exhaust gas purification function. Further, in the upstream portion of the three-way catalytic converter 11 of the exhaust pipe IO of the exhaust pipe 10, there is an O for detecting the oxygen concentration (A/F') in the exhaust gas.

Sensor 2K is provided.

The air-fuel ratio during idle operation in the above-mentioned idle speed control system is determined based on the detected output value AFSo of the air flow meter 2, for example, in the air-fuel ratio control system on the side of the electronic fuel injection control device. First, the basic fuel injection amount Tp is determined based on the calculated intake air flIQ and the engine speed NE, and the above 0.
The sensor 2K is used to detect the actual engine air-fuel ratio, and the basic fuel injection fiTp is feedback-corrected according to the deviation between the detected value and the set target air-fuel ratio, so that the set air-fuel ratio (in general, the theoretical Therefore, the final fuel injection ff1T in the air-fuel ratio control system is such that the air-fuel ratio is maintained at a value near 1).
The calculation formula is as follows.

T=Tp-a ・(1+KTw+KAs+KA!+K
M R) ... (2) However, Tp: Basic fuel injection amount α: 0. Air-fuel ratio feedback correction coefficient based on output Ktw: Water temperature correction coefficient KAS: Start-up correction coefficient KAI Increase correction coefficient after near idling KMR: Air-fuel ratio (mixture ratio) increase correction coefficient On the other hand, code 14
is an ignition plug provided in the cylinder head of the engine body 1, and a predetermined ignition voltage is applied to the ignition plug 14 via a distributor 17 and an igniter 18. The application timing, that is, the ignition timing, is controlled by the ignition timing control signal Igt supplied from the ECU 9 to the igniter 18. Further, reference numeral 19 denotes a knock sensor provided in the sill block portion of the engine main body I, which outputs a voltage output Vo corresponding to the intensity of occurrence of knocking in the engine, and inputs it to the ECU 9. Furthermore, reference numeral 20 is a boost pressure sensor 20, which detects the engine boost pressure B corresponding to the engine load and
Input to CU9.

The E'CU 9 is composed of, for example, a micro combimeter (CPU) which is a calculation unit, a control circuit for intake air amount, ignition timing, etc., memory (It OM and RAM), an interface (Ilo) circuit, etc. ing. In addition to the above-mentioned detection signals, the interface circuit of the ECU 9 receives, for example, an engine starting signal (ECU trigger) from a starter switch (not shown), an engine rotation speed detection signal NE from the crank angle sensor 15, and a crank angle signal SGT. , a detection signal TW% of the engine cooling water temperature detected by the water temperature thermistor 16, a throttle opening detection signal TVO detected by the throttle opening sensor 4, and an intake air amount detection signal AI? detected by the air flow meter 2, for example. Various detection signals necessary for normal engine control, such as '5o (Q), are also input.

The functions of the control section of the ECU 9 can be conceptualized as shown in FIG. 2, where, for example, an interrupt routine 200 for fuel injection control and an intake air amount calculation routine 300 are divided into a main routine 100 for various engine controls. At least two subroutines are provided.

Next, the detection control of the intake air m during idling operation by the ECU 9 of this embodiment will be described in detail with reference to the flowcharts in FIG. 3.

First, in step S1, a read timer TIME is set to read the detected value AFSo of the air flow meter 2.
The reading period T i (T i = I m5ec) and the value 5GF (l or O) of the crank angle signal SGT are read respectively.

Next, proceed to step S, where the above read timer TI
It is determined whether the ME setting value Ti=O (reading timing has arrived). If the result is YES, the intake air amount calculation timer interrupt flag Ti is set in step S3.
The value of p is set to Tir = 1 (interrupt execution), and the value of the read timer TIME is set to the initial value To in step S4, and the process proceeds to step S. However, if the answer is NO, the same process continues. The process proceeds to the judgment operation in step S.

In step S6, it is determined whether the value of the read value SGF of the crank angle signal SGT is 5GF=1, that is, whether the interrupt timing for fuel injection control has arrived, and if YES (arrival) In step S6,
After setting the value of the crank angle signal SG'r to O in step S
The fuel injection control (see FIG. 6), which is the interrupt routine of step 7, is executed.

On the other hand, in the case of NO (not arrived), the other side step S,
Then, it is determined whether or not the value of the interrupt timer flag TiF is 1, that is, whether or not the above-mentioned output of the air flow meter 2 can be calculated.
If YES, first in step S, the value of the above-mentioned interrupt timer flag TiF is reset to 0, and further in step S. The reading value AF S (i) of the output of the air flow meter 2 is the actual air flow meter output AFS.

4, and then proceed to step S II to calculate the reading value AFSo of the air flow meter output.
Linear interpolation shown in Figure 5 (prediction calculation using proportional allocation method)
, A F S (i)= ((1-T i/To)A
FS+, +AFSi)/(2-(Ti/To)).

Then, by the linear interpolation (prediction calculation), the step S
Intake air ffi while interrupt control of 7 is being executed
A F S i reading timing (see Figure 6a)
After calculating the intake air fi A F S i in step S11, in step Sat, the intake air amount A F S (i) within a predetermined sampling period (i) is calculated as shown in the following equation as before. The average value AFSs is calculated and used as the final intake air amount.

AFSs+=(AFS(i)+APS(i-+)+...
・A F S (i − n))/i In the configuration of the above embodiment, the detected value AF So of the air flow meter 2 is read at a predetermined reading cycle T i (1 m5ec), and the predetermined value of the read value A F S (i) is read. Period (i cycle period)
By calculating the average value AFSm, the intake air amount Q (Q=AFSa+), which is the basis of fuel injection amount control, is calculated.

On the other hand, a predetermined interrupt control means (step S7) is provided which gives priority to the calculation operation of the intake air ff1Q,
Interrupt control that gives priority to the calculation operation of the intake air amount Q is arbitrarily executed, but in such a case, the prediction calculation means (step S, ~5at) is activated to determine the intake air amount immediately after the interrupt control ends. As shown in Figs. 4 and 5, the intake air amount detection value ASFi during the interrupt control is proportionally distributed by linear interpolation from the detected value AFSo and the intake air amount detection value AFSi-+ before the interrupt control. A predictive calculation is performed to calculate the target average value AFS- of the intake air m.

Therefore, the execution of the above interrupt control does not reduce the number of times the original intake air amount is read, and the predicted value A
SFi itself is also proportionally distributed based on the most recent values before and after the interrupt control, and can be considered to be approximately equal to the actual measurement value, so the final calculated intake air m
Naturally, Q is also highly accurate.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram of an engine intake air amount detection device according to an embodiment of the present invention, Fig. 2 is a basic conceptual diagram of the control section of the device, and Fig. 3 is an intake air amount detection device of the above embodiment device. Flowchart showing detection and fuel injection side control operations,
FIG. 4 is a graph showing the characteristics of the airflow meter output in the above embodiment, FIG. 5 is an explanatory diagram showing the linear interpolation operation in the same embodiment, and FIG. 6 is the reading operation (a) of the airflow meter output It is a time chart showing the relationship with fuel injection control operation (b). l...Engine body 2...Air flow meter 3...Intake passage 5...Fuel injector 9...Engine control unit 15...
・Crank angle sensor 100...Engine control main routine 200...Fuel injection interrupt routine 300...Intake air amount calculation routine (air flow meter output) Fig. 5 Fig. 6

Claims (1)

[Claims] 1. An intake air amount detection means for detecting the intake air amount of the engine, and a detection value of the intake air amount detection means is read at a predetermined period;
An intake air amount calculation means that calculates the intake air amount for controlling the fuel injection amount by calculating the average value within a predetermined period, and a priority is given to the reading operation of the intake air amount calculation means in the predetermined period. In an electronically controlled engine, an electronically controlled engine is provided with an interrupt control means for performing interrupt control at a time, and a read value of a detection value of the intake air amount detection means immediately after the interruption control of the interrupt control means is completed, and a detection value read by the same means in the previous cycle. An intake air amount detecting device for an engine, characterized in that a predictive calculation means is provided for predicting and calculating a reading detection value of an original detection cycle during interrupt control of the interrupt control means based on the above value.