JPS59101562A - Air-fuel ratio controller of multi-cylinder engine - Google Patents

Abstract

PURPOSE:To control air-fuel ratio without causing any increase of the number of exhaust sensors, by controlling a fuel supply amount to be corrected in the operating range, in which the concentration of exhaust gas can not be detected in each cylinder, on the basis of a fuel supply amount corrective value for every cylinder obtained in the operating range in which the concentration of exhaust gas can be detected in each cylinder. CONSTITUTION:An engine arranges an air flow sensor 4 in a main passage 2e, exhaust sensor 9 in a main pipe 8e in the downstream of a manifold part 8f and a reference timing detector sensor 13 in a gear 12 connected to the crankshaft of an engine 1. The first memory device 14 stores in memory a delay time, after the reference timing till the sensor 9 detects the concentration of exhaust gas in each cylinder 1a-1d, while the delay time is classified by operating ranges A1-A16. The second memory device 15 stores in memory a deviation factor of air-fuel ratio from the target air-fuel ratio for obtaining an injection amount corrective value for each cylinder. A control circuit 17 controls a fuel injection amount to each cylinder to be corrected by a fuel regulator device 16, and in the operating ranges A11-A16 where detection for every cylinder is incapable, the circuit 17 controls the fuel injection amount to be corrected on the basis of the detected concentration of exhaust gas by the exhaust sensor 9 and the injection amount corrective value for every cylinder in the second memory device 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for a multi-cylinder engine that performs feedback control of the air-fuel ratio of each cylinder of the engine to a target air-fuel ratio based on the output of one exhaust sensor. .

Conventionally, an air-fuel ratio control device 1y for a multi-cylinder engine includes one air-air sensor disposed downstream of a collecting part of an exhaust manifold, and controls fuel injection 1j to each cylinder based on the exhaust gas concentration detected by the exhaust sensor. is uniformly controlled, and the air-fuel ratio of the entire engine is feedback-controlled to the target air-fuel ratio.

However, the intake air to each cylinder varies among each cylinder, and such intake air) ji: l
If the force to each cylinder, which has variations, is uniformly controlled, it is not possible to control the air-fuel ratio of each cylinder to a uniform air-fuel ratio. Therefore, in order to solve this problem, the applicant of this application has focused on the fact that the engine exhaust gas υS flows in a layered manner in the υ direction in the downstream of the exhaust gas collection section, and the exhaust gas concentration in each cylinder has been reduced. An application has already been filed for an air-fuel ratio control device for a multi-gas engine which is capable of detecting the concentration of exhaust gas and controlling the rough fuel ratio and Iil for each cylinder based on the detected exhaust gas concentration (see Japanese Patent Application No. 131,659/1983).

However, when the load is low, the amount of the exhaust gas is small, the flow velocity is low, and it does not form a very clear stratified structure. Problem 4: In addition, in the engine speed rotation range, the flow velocity of exhaust gas increases, so there is a time delay in detection by the exhaust sensor, so even in such a high speed rotation range, the exhaust gas from each cylinder increases. Concentrations are difficult to detect.

Although it is conceivable to provide an exhaust sensor for each cylinder in order to solve this problem, this would result in a problem of increased costs.

The present invention has been made in view of this problem, and in an operating region where exhaust gas concentration can be detected for each cylinder, the amount of fuel supplied to the cylinder is corrected based on the detected exhaust gas concentration. At the same time, the correction control value is stored as the cylinder-by-cylinder fuel supply correction value for the cylinder, while in the cylinder-by-cylinder detection impossible operation region, the exhaust gas concentration detected by the exhaust sensor and the cylinder-by-cylinder fuel supply amount correction value are stored. By correcting and controlling the fuel supply amount to each cylinder based on the fuel supply amount correction value for each cylinder, it is possible to control the air-fuel ratio for each cylinder without increasing the number of exhaust sensors. The present invention aims to provide an air-fuel ratio control device for a cylinder engine.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and in the figure, 1 indicates a first
The engine 1 is a four-cylinder engine having the first to fourth cylinders 1a to 1d, and the engine 1 is ignited in the order of the first, third, fourth, and second cylinders. Reference numeral 2 denotes an intake passage consisting of a main passage 2e and first to fourth branch passages 2a to 2d, and the main passage 2C is provided with a throttle valve 3 for controlling the amount of air introduced into the passage 2C. Main passage 2 above
An air flow sensor 4 for detecting the intake air slope is provided on the upstream side of the throttle valve 3 of
An air cleaner 5 is provided at the upstream end of e. Further, the first to fourth branch passages 23 to 2d are the first to fourth branch passages 23 to 2d.
to the fourth cylinders 1a to 1d, and each branch communication ff? i 2 a to 2d have fuel injection valves 16a to 2d.
16d is provided.

And 8 is the first to fourth branch pipes 8a to 8d and the main pipe 8e.
The branch pipes 8a to 8d of the exhaust manifold 8 are connected to the first to fourth cylinders 1a to 1d.
The main pipe 8C downstream of the collecting part 8f where the branch pipes 8a to 8d are collected includes the main pipe Qt 8e.
Exhaust sensor 9 for detecting the concentration of exhaust gas passing through
The exhaust sensor 9 is, for example, a U sensor, and is designed to generate a linear output corresponding to the exhaust gas concentration. Note that 10 is the main pipe 8e above.
This is an exhaust gas purification device disposed downstream of the exhaust sensor 9.

Further, a first gear 11 is connected to the crankshaft (not shown) of the engine 1, and a second gear 12 having twice the number of teeth is meshed with the first gear 11. rotates at a rotation speed of 172 of the engine 1, and a reference timing detection sensor 13 is disposed on the left side of the second gear 12 in the drawing. The reference timing detection sensor 13 is for detecting the reference timing of the operation of the engine 1, and detects, for example, the timing when the piston of the first cylinder 1a is at the compression top dead center.

Although not shown, a rotation sensor for detecting the engine rotation speed is provided near the first gear 11, and the outputs of the rotation sensor and the air flow sensor 4 are used as operating information indicating the operating state of the engine 1. I'm leaning on it.

Reference numeral 14 is a first storage device, which stores delay times tn and m for each cylinder 1a to ld in each operating state, which are determined in advance through experiments (hereinafter, n is the operating region number and n =
1 to 162m are cylinder numbers (m = 1 to 4) are stored, and here, 1 river at the time of delay means that the exhaust sensor 9 detects the exhaust gas concentration of each cylinder 1a to 1d from the reference timing. It is the time that elapses until the timing of engine rotation, and the operating range is divided into 16 ranges A corresponding to the values of the intake air amount q and the engine speed N, as shown in Fig. 2 (a).
+ M-Ass.

Further, as shown in map A, the first storage device 14 stores a target air-fuel ratio MAn having the same value for each cylinder for each of the above operating regions determined by the desired intake air amount q and the engine speed N. (See Figure 2(b)). Furthermore, 15 is a second storage device, which stores the actual air-fuel ratio and target air-fuel ratio for each cylinder in order to obtain the injection timing correction values for each cylinder 1a to 1d in each operating region, as shown in map B. Air-fuel ratio deviation rate EM
n, 1 are stored (see FIG. 2(c)).

Further, 16e is a drive circuit that opens and closes each of the fuel injection valves 16a to 16d, and the drive circuit iW416e and each of the fuel injection valves 161 to 16d control the amount of fuel to be supplied to each cylinder 1a to 1d for each cylinder. A fuel adjustment device 16 for adjustment is configured.

17 is a control circuit, which is connected to the exhaust sensor 9.
．． This is for correcting and controlling the fuel injection amount to each cylinder by the fuel adjustment device 16 in response to the outputs of the near flow sensor 41 rotation sensor and reference timing detection sensor J3. More specifically, the control cycle n'i'i 17 determines that the exhaust gas concentration detected by the exhaust sensor 9 at the present time is 1d, the concentration of the exhaust gas is determined from which cylinder, and based on the detected exhaust gas concentration, the amount of fuel injection to the cylinder is corrected and controlled, and the correction control is applied to the cylinder-by-cylinder injection of the cylinder. This is stored in the second storage device 15 as a partial correction value.

In the operation region in which every 10,000 cylinders cannot be detected (area All-At5), the control circuit 17 uses the exhaust gas concentration detected by the exhaust sensor 9 and the injection amount correction value for each cylinder in the second memory device -1α15. Based on this, the fuel injection amount to each cylinder is corrected and controlled.

FIG. 3 shows a flowchart of the arithmetic processing of the control circuit 17. In the figure, 20 reads the output of the two-legged reference timing detection sensor 13, and outputs the outputs of the two-legged airflow sensor 4 and rotational speed sensor to the operating range. Step 21 reads the target air-fuel ratio MAn in the operating range from the first storage device 14, and calculates the basic fuel injection amount 'I'Bn by TBn = k X94. This is the step to find out. Here, k is a constant determined in advance through experiments, and 22.23 is a determination step for determining whether the operating state of the engine 1 is in the cylinder-by-cylinder undetectable operation range, and determination step 22 is a step of determining a low load region when the intake air uQ is less than a predetermined air amount QO in the region, and determination step 23 is a step of determining the engine rotation speed N.
This is a step of determining a high rotation region when the rotation speed is higher than a predetermined rotation speed NO.

24 is a step of calculating the current actual air-fuel ratio M A n, Hl of each cylinder 1a to 1d when the operating state of the engine 1 is in the operating region that can be detected for each cylinder. Actual air-fuel ratio MA r of cylinder 1a
, I, when the delay time t1,1 of 41 IJ1a stored in the first storage device a14 has elapsed after receiving the output of the reference timing detection sensor 13, the exhaust gas at this point is determined. The output of the sensor 9 is read as the detected exhaust gas M degrees of the first cylinder 1λ, and the actual air-fuel ratios MA+, + are determined based on the concentration.

In addition, 25 represents each energy at the present moment (ratio ratio F of Gi 1 a to 1d, Mr1.■-= MAH, nl/ MAn
Step 26 is to obtain the air-fuel ratio ratio Eht.
"n, m for each cylinder m and operation failure area" second storage device i
This is the step of storing the data in J.'15.

27 is cylinder), H, (2\fuel injection t7 Tl n
, m, and this (t is the step 2 above)
Tl using the air-fuel ratio deviation rate EM+i, m recorded in 6.
Determined from n, m-'I'Bri X EMn9m.

28 is 19 kokumachi fuel injection lit'rx, 1. I.

In this step, an interrupt is processed at the timing of the 1.d shot.

29 is a step of reading the current revised air-fuel ratio M A H, Hl of each cylinder 1a to 1d when the four-wheel rotation state of the engine 1 is in the undetectable operation i region for each cylinder;
30 is the revised air-fuel ratio MA'n for each cylinder,, the Ura IE air-fuel ratio MM with a curved version of n! This is a step to obtain 1 m, and this is for each driving area memorized in step 26 above.
From the average of the air-fuel ratio deviation rate EMn,m of the cylinder core, here E r, 101 is the air-fuel ratio deviation rate in Mag B.
II and I11 are averaged over areas A1 to A++i in Baura m, or the market value is calculated by averaging them, and in the latter case, the vehicle size can be determined as appropriate by experiment. .

31 is the corrected air-fuel ratio deviation rate EMn, m = MMn,
, 11/MAn, the extracted air-fuel ratio deviation rate EM11. Inject iij into the cylinder 41 in step 27 using n: -1'In, m-'
Find I″Bn
8, the output is output for each cylinder.

Next, the operation will be explained.

During operation of the engine 1, fresh air is taken into the intake passage 2 according to the opening degree of the throttle valve 3, and the intake air is detected by the air flow sensor 4, and the exhaust passage Ig is detected by the air flow sensor 4.
The exhaust gas concentration in the main pipe 8e of the engine B is detected by the exhaust sensor 9, and the reference timing detection sensor 13 detects the engine 1 base (1β timing, that is, the timing when the piston of the first cylinder 1a is at its compression top dead center). The engine speed is detected by a rotation sensor,
The outputs of these sensors 4, 9, 13 and the rotation sensor are applied to the control circuit 17. The first storage device 14 also stores the target air-fuel ratio MA for each operating region shown in map A.
Delay times tn and m for each cylinder and each operating range are stored.

First, the operating state of the engine l is detected every 14 times +jJ
The following describes the case where the function operation fit J area number is used. Here, the above-mentioned cylinder-by-cylinder detection iiJ function operating range and (J, each cylinder-by-cylinder exhaust gas concentration 1y can be detected) are defined as
) as shown in 4-Shoulder Area 81 to Ag, when the intake air amount Q is greater than the predetermined air 1 (4HQo and the engine speed N
is an operating range lower than the predetermined rotation speed NO, and the engine 1 is currently in the operating range A4 (i = 1 to 9), the exhaust gas from each cylinder 1a to 1 (1 is as shown in Fig. 4 (a) As shown in the ignition order, the exhaust gas of 1st, 3rd, 4th, 1st, 2nd air, I, III, IV
, H flows through the main pipe 8C of the exhaust manifold 8 in the order of yz L. In this case, the system? 11v times ii
As shown in FIG. 3, in step 20, the outputs of the airflow sensor 4 and rotation sensor, that is, the intake air amount 9 and the engine speed N, are read as operating information, and in step 21: A31-1 (! The target air-fuel ratio MAi in the operating state is read based on the operating information read from the manufacturing unit 14, and the basic fuel injection (K'I'B) is calculated using the target air-fuel ratio MAi in the operating state.
Find i.

Also, in step 22, it is determined whether or not the intake air fit Q is greater than the predetermined intake air amount Qo. Rotation speed No.
7, and determine whether this IL″3 is N〈IN
O, so step 23 to step 24゜25.2
6. Proceed at Keiwa on 27th.

Then, in the upper grip control cycle 1 (, 17 is step 24, the delay time for each cylinder ' I ' + ' 1, 8 +
[1 r 4 + ' 1 r 2 elapses (
(see FIG. 4), the outputs of the exhaust sensor 9 at this point are respectively the first and second outputs. Third. 4th. It can be read as the detected exhaust gas concentration of the second cylinder, and from the valley detected exhaust gas concentration, the volume 1
i-, j to the actual air-fuel ratio of l a to l d 1A i,
+ x MA i,4 is determined, and in step 25, the air-fuel ratio deviation rate EMi,
1-EMi,4 is determined, and in step 26, the air-fuel ratio deviation ratios EMi,l, EMi,4 are recorded in the second storage device 15 for each operating region and cylinder as shown in map B.
4. Fuel injection every time. I
``qt'l'Ii, t~''Ii, 4. '(
L/Ni control cycle 1) i417 is in step 28 '-fuel injection #'J'rti for each cylinder: 'Ii, m to v
4++ut times IFij 16 e and fuel injector t6
After doing steps a to l6d, the fuel is injected at the injection timing for each cylinder, and the process returns to step 20 and circulates through steps 20 to 28.

Next, the operating state of engine 1 is cylinder word undetectable operation fu'.
The case where it is in the i area will be explained. Here, the cylinder-by-cylinder undetectable operation region is the 1. 'η (There are three areas A10 to A+r+゛C, which is intake air Rj)
Low load area A10 to A where Q is less than/S the specified air meter QO
Assuming that I2 and the engine speed N are comprised of high speed ranges AI8 to A16 where the engine speed is higher than the predetermined speed NO, and the engine 1 is currently in the operating range AJ (j=10 to 12), each cylinder 1
The exhaust gases from 3 to 1d are mixed as shown by X in Figure 5(a), and in this case, the control circuit 17 in F is at step 22, and the operating state in this case is low load overhead, i.e. It is determined that the operation is in the undetectable operation III region, and the process proceeds from step 22 to steps 29, 30 and 31, and in step 29, the delay time 'J+' is determined from the waste C store timing.
+ 'J+8+ '' 4 + Ej, 2 has passed J! Then, the output of the exhaust sensor 9 at that point is read as the detected provisional exhaust gas concentration of the 1st, 3rd, 4th, and 2nd cylinders. Temporary air-fuel ratio M from each exhaust gas concentration
Aj, l, MA'j, 8. MA'j, 41ΔIA
Find 'j, 2. Here, nr from each cylinder 1a to 1d
This provisional air-fuel ratio M, A'J
, 1 to MA'j, and 4 are often the same values, and in this embodiment, as shown in FIG. 5(1)), they are a constant value and 1. It's on. Then, in step 30, '1.' is written in the second storage device d15. Area A1 for each cylinder that is tt
Read the air-fuel ratio deviation ratio EN1n,m of A9, and use the average air-fuel ratio deviation ratio EMm averaged for each cylinder to correct the "predetermined air-fuel ratio MA° ~ MA j, 4" to obtain the corrected air-fuel ratio. MM3.~J,1 MMj,4 is determined, and in step 31, the corrected air-fuel ratio ratio EMj,1~EMj,< for each cylinder is determined.

After this, the -F,,i12 control cycle 17 proceeds from the step knob 31 through the path of steps 27 and 28, and the step knob 27 injects the corrected fuel injection hl T1 j , 1-TI
J, 4 is determined, and in step 28, the iE fuel injection amount ``In, m'' is determined by the fuel injection valve 1 at a predetermined injection timing.
61 to 16d to inject, then return to step 20, and further step 20, 21, 22, 29, 30,
It will circulate along the routes 31, 27, and 28.

Also, when the engine 1 is in the operating range A4 sy A46, the exhaust gas from each cylinder 1a to 1d is in a stratified manner.
However, because the flow rate is fast, the time required for the exhaust gas to pass through the exhaust sensor 9 is shortened, and the exhaust sensor 9 has a time delay in its detection, making it difficult to detect the exhaust gas concentration for each cylinder. It is something that cannot be done. In this case, the control port d (i 17 is the step
9, and thereafter proceed in the same manner as in the case of the iul area AIO to AI2.

In this way, in the cylinder-by-cylinder detectable operating region, this performance 1 giant example device corrects and controls the fuel injection [11] to the cylinder based on the exhaust gas concentration detected for each cylinder. In this case, the exhaust gas concentration detected by the 4JL air sensor and "-"? n! , iE ib'l @l
.

In the above embodiment, the target air-to-air heat ratio MA,n is set to the same value for each cylinder in each operating region, but a different value may be used for each cylinder. Furthermore, although the provisional air-fuel ratio MA'j1m in the low load range of 60 was explained as being a constant value as shown in Fig. 5(b), this is not necessarily constant and variations may occur. In this case, you can calculate the average and use it.

Furthermore, the above-mentioned air-fuel ratio deviation rate EM port 2m is determined and stored for each cylinder and for each operating head A+ -Ao, but this is not necessarily necessary for each f, K I:f1 region. For example, it may be stored as an average or a weighted average over 1 to A9 in the driver's head for each cylinder. Further, the exhaust gas sensor 9 may be one that shows a sudden change in output near the stoichiometric air-fuel ratio.

The air-fuel ratio side of the multi-cylinder engine according to the present invention as described above?
According to the dtl device, in the cylinder 4fi detectable operating region where the exhaust gas concentration can be detected for each cylinder, the fuel supply 171 to the cylinder is corrected based on the detected exhaust gas concentration, and the correction control amount is is stored as the cylinder-by-cylinder lighting supply ii correction copy of the relevant cylinder, while in the operation region where cylinder-by-cylinder detection cannot be performed, the above-mentioned exhaust sensor detects the The fuel supply to each cylinder is based on the positive value of the fuel supply for each cylinder (A is set to the correction side Ql, so the number of exhaust sensors is increased by 7). Accuracy of air-fuel ratio control every 4A16'' even in the range (
There are effects that can be done.

[Brief explanation of the drawing]

Figure 1 shows the air-fuel ratio of a multi-cylinder engine according to an embodiment of the present invention! FIG. 2(a) is a characteristic diagram for explaining the driver's head installation, and FIG. 2(b) is a diagram showing the connection configuration of the l+' control system. fc) is a diagram showing the map, FIG. 3 is a diagram showing a flowchart of the processing procedure of the control circuit, and WS 4 #! 7
．． 1 (Xl). 5(b), FIGS. 5(a) and 5(b) are diagrams for explaining the effect. DESCRIPTION OF SYMBOLS 1...Engine, 4...Operating state detection sensor (air flow sensor), 8...Exhaust manifold, 8f...Collection part, 9...Exhaust sensor, 13...Reference timing detection sensor, 14...first storage device α, 15...5'
Rod 2 memory device, 16...Fuel adjustment device 6 (drive circuit,
fuel injection valve), 17... control circuit. Patent applicant Toyo Kogyo Co., Ltd. Agent Patent attorney Hayase ψ −1
Figure 17N-N during the engine cycle. Engineering υ5:/Nippon t■-

Claims (1)

[Claims] (1) An exhaust sensor disposed downstream of the collecting part of the exhaust manifold, an operating state detection sensor that detects the operating state of the engine, a reference timing detection sensor that detects the base 7F timing of the engine, and the above base timing. A first memory device stores in advance the delay time 11 from 11 to the timing at which the exhaust sensor detects 61 degrees of exhaust gas in each cylinder in correspondence with each operating state of the engine; a second storage device in which a cylinder combustible supply amount correction value related to variation is stored; a fuel adjustment device that adjusts the amount of fuel supplied to each cylinder by θM for each cylinder; and the exhaust sensor; Driving letter! Receives each output of the dust detection sensor and the reference timing detection sensor, and in the 4:1 transmission range where each cylinder can be detected, each cylinder corresponds to the above basic timing and the current operating state stored in the above J151 storage device. It is determined from which cylinder the exhaust gas concentration currently detected by the exhaust sensor is coming from from the delay time data of At the same time, the correction control amount is adjusted to 1 of the cylinder.
'' is stored in the second storage device as a cylinder fuel supply amount correction value regarding variations from the standard air-fuel ratio, while in the cylinder-by-cylinder undetectable operating region, the exhaust gas concentration detected by the exhaust sensor and the exhaust gas concentration in the second storage device are and a control circuit that corrects and controls the amount of fuel supplied to each cylinder by the fuel adjustment device based on the cylinder fuel supply amount correction value.