JPH01106934A - Control device for air-fuel ratio of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve an operating property at a steady time and at a gently accelerating time by correcting an injecting quantity based on a changing quantity when the changing quantity of a load parameter is above a defined value, while averaging a defined number of changing quantities immediately before to correct the injection quantity when the changing quantity is less than the defined value. CONSTITUTION:The detected value from an intake pressure sensor 3 is inputted as a load parameter into a control circuit 10 and, together with the detected values of crank angle sensors 5, 6, an O2 sensor 9, a water temperature sensor 11, a throttle switch 13, a throttle opening sensor 14, etc., used to operate and control the valve opening time of a fuel injection valve 7. The control circuit 10 calculates a changing quantity per unit time based on the detected value of the intake pressure sensor 3 and, when this changing quantity is above a defined value, judging to be the transient state of acceleration/deceleration, etc., corrects the injection quantity based on this changing quantity. When the changing quantity is less than the defined value, changing quantities (n) in number which are stored last time are modulatingly controlled to correct the injecting quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air-fuel ratio control device for an internal combustion engine, and more particularly, the present invention relates to an air-fuel ratio control device for an internal combustion engine. The present invention relates to an air-fuel ratio control device for an internal combustion engine that performs correction.

[Conventional technology]

Equipped with an electronic control device that detects engine load status parameters (for example, intake pipe pressure and throttle opening), calculates the amount of fuel to be injected according to the detected parameters, and injects fuel according to the calculated value. Some engines correct the fuel injection amount TAU based on the amount of change in a parameter per unit time.

In such an engine, for example, when the detected value PM of the intake air pressure is used as a load state parameter, the intake air pressure within a unit time can be detected using the formula: TAU=TP+K ・ΔPM...■ Amount of change in value PM ΔPM
The basic injection amount TP is corrected to obtain the injection amount TAU. Note that K is a coefficient.

In the above engine, when calculating the injection amount TAU using the formula (■), it is difficult to place too much emphasis on the transient response of the detected intake air pressure value PM in the input circuit of the detected intake air pressure value PM and the subsequent digital filter processing. Even though the engine is in steady operation due to the influence of ripple during steady operation, unnecessary injection amount correction is performed due to the amount of change ΔPM in the detected value H of the intake air pressure. performance) and emissions deteriorate.

Therefore, as a countermeasure, the above-mentioned organization has adopted (1)
When the amount of change Δ is less than a predetermined value, the engine is considered to be in steady operation, and the injection amount is not corrected based on the amount of change Δ.

(2) Powerful digital filter processing is performed in engine operating ranges where the throttle opening is large and the ripple is particularly large during steady engine operation.

A technology has been proposed (Patent Application No. 6l-27702
0).

[Problem that the invention seeks to solve]

However, in the countermeasure shown in (1) above, when the amount of change ΔPM is less than a predetermined value, ΔPM is set to O, so in slow acceleration or slow deceleration where the amount of change in load is less than the predetermined value, There is a problem that no transient correction is applied to the injection amount, resulting in poor acceleration performance.

In addition, with the countermeasure shown in (2), in engine operating ranges where the throttle opening is large and the ripple is particularly large during steady engine operation, the time constant of the filter is increased to more powerfully reduce high-frequency noise. However, it has no effect on ripples in steady-state operating conditions where the throttle opening is not large, and conversely, unnecessary transient corrections are performed when ripples exceed the predetermined value in steady-state operating regions. There is.

The purpose of the present invention is to solve the problems with the conventional engine that performs transient correction of the injection amount, to avoid impairing the calculation of the transient correction amount in a slow transient state, and to make the calculation of the transient correction amount stable even in any steady operating state. Change amount Δ due to constant ripple
An object of the present invention is to provide an excellent air-fuel ratio control device for an internal combustion engine that can prevent calculation of PH, eliminate fluctuations in injection amount in the steady operating range of the engine, and improve drivability and emissions.

[Means for solving problems]

The configuration of an air-fuel ratio control device for an internal combustion engine according to the present invention that achieves the above object is shown in FIG.

The load detection means detects a load state parameter of the engine, and the change amount detection means detects the amount of change in this load state parameter within a unit time. Then, when the amount of change is less than a predetermined value, the average value calculation means calculates the average value of this amount of change and the amount of change within a predetermined unit time immediately before, and the injection amount correction means calculates the average value of the amount of change within a predetermined number of unit times immediately before. The transient correction amount is calculated based on the average value obtained.

[For production]

According to the air-fuel ratio control device for an internal combustion engine of the present invention, the amount of change in the load state parameter of the engine within a unit time is detected, and if the detected amount of change exceeds a set value, the amount of change is determined based on the amount of change. When the injection amount is corrected and the detected amount of change is lower than the set value, the average value of this amount of change and the amount of change detected in each of the n unit times immediately before this unit time is calculated. , the injection amount is corrected based on this average value.

Embodiments of the present invention will be described in detail below using the drawings.

〔Example〕

FIG. 2 schematically shows an electronically controlled fuel injection type internal combustion engine equipped with an embodiment of the air-fuel ratio control device for an internal combustion engine according to the present invention. In this figure, an intake passage 2 of an engine 1 is provided with a pressure sensor 3 for detecting the internal pressure of the intake pipe as means for detecting the amount of intake air. For example, a SAW type sensor using a surface acoustic wave that causes a propagation phase delay due to strain proportional to pressure is used as the pressure sensor 3, and a pressure signal is extracted at an oscillation frequency that is inversely proportional to this phase delay time. This pressure signal is supplied to an A/D converter 101 with a built-in multiplexer of the control circuit 10. The distributor 4 is provided with a crank angle sensor 5 whose axis generates a pulse signal for detecting a reference position every 180° CA, and a crank angle sensor 6 which generates a pulse signal for detecting a reference position every 30' CA. There is. Pulse signals from these crank angle sensors 5 and 6 are supplied to an input/output ink face 102 of a control circuit 10, and the output of the crank angle sensor 6 is supplied to an interrupt terminal of a CPU 103.

Further, the intake passage 2 is provided with a fuel injection valve 7 for supplying pressurized fuel from a fuel supply system to the intake port for each cylinder.

In addition, in the cooling water passage W of the cylinder block of engine 1,
A water temperature sensor 11 is provided to detect the temperature of cooling water. The water temperature sensor 11 generates an analog voltage electrical signal corresponding to the temperature THW of the cooling water. This output is also A/
The signal is supplied to the D converter 101.

The control circuit 10 is configured using, for example, a microcomputer, and includes the aforementioned A/D converter 101. Input/output interface 102. In addition to the CPU 2O5, a ROM 2O3, a RAM 2O3, a backup RAM 109 that retains information even after the ignition switch is turned off, and the like are provided, and these are connected by a bus 110.

In this control circuit 10, a down counter 106° flip-flop 107. and a drive circuit 108 for controlling the fuel injection valve 7. That is, the fuel injection amount T
When AU is calculated, the fuel injection amount TAU is preset in the down counter 106 and the flip-flop 1
07 is also set. As a result, the drive circuit 108 starts energizing the fuel injection valve 7.

On the other hand, when the down counter 106 counts the clock signal (not shown) and the carrier voltage terminal reaches "1 level", the flip-flop 107 is reset and the drive circuit 108 activates the fuel injection valve 7. In other words, the fuel injection valve 7 is energized by the above-mentioned fuel injection amount TAU, and therefore, an amount of fuel corresponding to the fuel injection amount TAU is sent into the combustion chamber of the engine 1.

The control circuit 10 also includes an intake air temperature sensor (not shown),
Detection signals are sent from a throttle switch 13 that detects the opening of the throttle valve 12, an opening sensor 14 of the throttle valve 12, an oxygen concentration sensor 9, a vehicle speed sensor 17 provided on a speedometer cable from the transmission 16, etc. . Furthermore, an ignition signal is output from the control circuit 10 to an igniter built in the distributor 4, and thereby the energization of the spark plug 15 is controlled, but since these are not directly related to the present invention, a description thereof will be omitted.

The detection signal of the pressure sensor 3 is detected by the A
The signal is converted into a binary signal by the /D conversion routine, and stored in the RAM 105 each time as data representing the intake pipe pressure value PM, either as is or after being subjected to rough processing.

Signals for every 30'' crank angle from the crank angle sensor 6 in the distributor 4 are sent to the input/output interface 10.
2 into the control circuit 10, and the rotational speed Ne
and a 30°-interrupt signal for calculating the fuel injection amount TAU.

Next, the operation of the above-mentioned control circuit 10 will be explained using the flowcharts of FIGS. 3 and 4.

FIG. 3 shows the operating procedure of the air-fuel ratio control device for an internal combustion engine according to the present invention, and this procedure is performed every revolution in the case of an engine that injects once per revolution.

In the embodiment shown in FIG. 3, the intake air pressure PM during one rotation is
Control in an engine that measures the intake air amount using the intake air pressure that performs transient correction of the injection amount using the following equation, TAU=TP+K・ΔPM・old...■ will be explained using the change amount ΔPM.

In step 301, the A/D conversion value PMN of the latest PM detection value from the pressure sensor 3 is stored in the RAM 105 as the current smoothed value PMN. Annealed value PM
N, is the A/D conversion value of the current PM value detected by the pressure sensor 3, and is the previously calculated PM smoothing value PMN.
This is the weighted average value of M+ −+ .

This smoothed value PMN is obtained by interrupt processing at predetermined time intervals, for example every 4 ms, by the PM A/D conversion post-processing routine shown in FIG.

In FIG. 4, first, in step 401, the A/D conversion value of the latest PM value detected by the pressure sensor 3 is PMA.
D and is stored in the RAM 105 as C.
P U2O5 stores the previous rounded value PMN=-+ in RAM1
05, and calculate the smoothed value PMN direct using the following formula.

PMN+ =1/m((m-1)PMN=-+ +PM
AD)--■Then, in step 403, the current rounded value PMN is calculated.

is stored in the RAM 105 as the previous rounded value PMN+-+, and the process returns.

In step 302, the current rough value PMN is subtracted from the previous rough value PMNO (one revolution before the engine), and the amount of change ΔPM in intake air pressure between the previous time and this time is determined, and this amount of change ΔPM is stored in the RAM 105 as DLPMI. is memorized.

In step 303, the absolute value of this amount of change DLPMI is compared with a reference value LVLPM for transient discrimination.

Step 303 DLPMI ≧LVLPM
(7) (YES) indicates that the engine is in a transient operating state, and the process proceeds to step 304, where DLPMI is stored in the RAM 105 as the amount of change DLPM for correction, and the DLPM
= DLPMI and proceeds to step 306. on the other hand,
l DLP indicates the steady operating state or slow acceleration state of the engine.
If MI l < LVLPM (NO), step 30
Proceeding to step 5, the value of the amount of change DLPM for correction is calculated using the following equation.

DLPM ←! /i (DLPM1+DLPM2+DL
PM3+DLPM4) ...DLPM in 00 type
2 is the amount of change DLPMI in the intake air pressure at step 302 of the previous routine, and DLPM3 is the amount of change DLP of the intake air pressure at step 302 of the routine before the previous one.
MI, DLPM4 is step 30 of the three previous routines.
2, and in this example, the amount of change DLPMI in the intake air pressure between this time and the past three times.
The average of MI is used as the amount of change DLPM for correction.

Steps 306 to 308 are for updating the past three intake air pressure changes DLPMI to the latest values. In step 306, DLPM4 is updated by DLPM3, and in step 307, DLPM3 is updated to DLPM3.
In step 30B, DLPM2 is updated by DLPMI. And step 30
At step 9, the current rounded value PMN is stored in the RAM2O3 as the previous rounded value PMNO (one revolution before the engine).

After this, in step 310, the amount of change OLP for correction obtained in step 303 or step 305 is
Find the transient correction amount K - DLPM from M, TAU = T
Transient correction of the injection amount to -DLPM is performed on P+. After that, corrections are made using detection signals from the cooling water temperature sensor 11, intake temperature sensor (not shown), throttle switch 13, opening sensor 14, oxygen concentration sensor 9, battery voltage, etc., and the final fuel injection amount is determined. Although it is determined as the injection pulse width, this calculation is not directly related to the present invention and will therefore be omitted. Thereafter, the pulse width is temporarily stored in the RAM 105, and the fuel is injected by the CPU 2O5 when the injection timing comes. At the same time, the CPU 103 enters the injection amount end time in the down counter 106 according to the injection pulse width calculated as described above.

Next, a change in the value of the correction change amount DLPH calculated by the air-fuel ratio control device for an internal combustion engine of the present invention will be explained using FIG. In this embodiment, the reference value LVLPM for transient discrimination is set to 7, and a state in which the amount of change in intake air pressure DLPMI does not reach 7 is defined as a steady-state ripple or slow acceleration state of the engine, and a state in which the amount of change in intake air pressure DLPMI is 7 or more. It is considered as a transient state at the time of .

As shown in FIG. 5 (al), the operating mode of the engine is in a steady operating state from time to to time t1;
From time t2 to time t2 is a slow acceleration state in the early acceleration stage, from time t2 to time t3 is a transient state in the middle acceleration stage, from time t3 to time t4 is a slow acceleration state in the late acceleration stage, and from time t4 to time t5. It is assumed that the period up to this point is a steady operating state, and that noise occurs between time t5 and time t6. In such an operation mode, when the reference value for transient discrimination is less than 7, the amount of change DLPM D for correction is the amount of change in the intake air pressure obtained in the past four times in step 305. Therefore, time t.

The correction variation DLPM is not affected by ripples during normal operation from to time t1. Furthermore, during the initial slow acceleration from time t1 to time t2, the correction change amount DLPM increases, although there is some time delay, so the fuel injection amount is corrected in the direction of increasing the amount, so that acceleration performance is not impaired.

On the other hand, when the reference value for transient discrimination after time t2 is 7 or more, the DLPM (=DLPM
The transient correction amount is calculated using 1) as is. Also,
When DLPMI falls below the reference value 7 between time t3 and time t4, the value obtained in step 305 is entered in DLPM, and the fuel injection amount is rapidly reduced even during slow acceleration in the latter half of acceleration. There is no.

As described above, the air-fuel ratio control device for an internal combustion engine of the present invention does not impair the calculation of the transient correction amount in a slow transient state, and also prevents the calculation of the amount of change in intake air pressure due to steady ripple in a steady operating state. , fluctuations in the injection amount in steady state are eliminated.

Although the present embodiment describes correction of the fuel injection amount, the present invention is also effective when applied to a structure in which the ignition timing is transiently corrected using the Δ gate. Further, the present invention is effective for all phase advance control using differential element Δgate, and PM+KI・ΔPM PM+KI・ΔPM 10a・ΔΔPM PM+KI・ΔPM+Kg・ΔΔPM+3・ΔΔΔ
Even in the case of high-order derivatives such as PM, noise components can be removed by using an average Δ gate with a long unit time during slow acceleration/deceleration, and high-order derivatives that use it can also prevent unnecessary value calculations during steady state. This makes it possible to eliminate fluctuations in the injection amount and ignition timing in a steady state without impairing the calculation of the transient correction amount in slow transients.

In addition, in the above embodiment, ΔPM for determining the transient state is set to engine 1.
It is calculated for each rotation, but in the 4ms interrupt routine, the PM value before the smoothing process (directly or using the PM value after the smoothing process,
ΔPM may be calculated every A/D conversion period of the gate value. Furthermore, when the PM value is A/D converted through a filter that achieves both ripple removal and responsiveness, smoothing of the PM value is not necessary.

Furthermore, the present invention can be similarly applied to an engine that calculates the amount of fuel to be injected using a load condition parameter (for example, throttle opening) other than the engine's intake pipe pressure, and injects fuel according to the calculated value. It is possible.

〔Effect of the invention〕

As explained above, according to the present invention, when the amount of change in the engine load condition parameter within a unit time exceeds the set value, the injection amount is corrected based on this amount of change, and the amount of change is adjusted to the set value. If it is lower, the injection amount is corrected based on the average value of this amount of change and the amount of change in each of the n unit times immediately before this unit time, so the drivability during slow acceleration and steady operation is improved. This has the effect of improving emissions and preventing deterioration of emissions.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram showing the configuration of the air-fuel ratio control device for an internal combustion engine according to the present invention, FIG. 2 is a schematic diagram of an engine equipped with the air-fuel ratio control device for an internal combustion engine according to the present invention, and FIGS. 3 and 4 is a flowchart showing the operation of the control circuit of FIG. 2, and FIG. 5 is a time chart showing the operation of the air-fuel ratio control device for an internal combustion engine of the present invention. 2...Intake passage, 3...Pressure sensor, 4...
...Distributor, 5.6...Crank angle sensor, 7...Fuel injection valve, 1o river control circuit.

Claims (1)

[Scope of Claims] 1. Load detection means for detecting a load state parameter of the engine; Change amount detection means for detecting the amount of change in this load state parameter within a unit time; When the amount of change is less than a predetermined value includes an average value calculation means for calculating the average value of this amount of change and the amount of change in a predetermined unit time immediately before this, and an injection amount correction unit that calculates a transient correction amount based on the obtained average value. An air-fuel ratio control device for an internal combustion engine, comprising: means; 2. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the load state parameter is a detected value of intake air pressure. 3. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the load state parameter is a detected value of intake air amount. 4. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the load condition parameter is a detected value of a throttle opening of the internal combustion engine.