JPS58214649A - Control of air-fuel ratio of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the fuel consumption, reduce the harmful components in exhaust gas, and suppress acceleration and deceleration shock by correcting the value of lean air-fuel ratio determined in accordance with the load of an engine according to the load variation rate of the engine. CONSTITUTION:A controller 50 calculates a fuel injection quantity on the basis of the data of each sensor and outputs said value into a fuel injection valve 23, and further calculates a bypass air quantity and outputs said value into a bypass flow-rate controlling valve 20. Air-fuel rate control by the controller 50 is performed by switching the air-fuel ratio to either a theoretical air-fuel ratio or a lean air-fuel ratio. When control is executed through a lean air-fuel ratio, the lean air-fuel ratio is set to a value in correspondence with the load of the egine, and the value thus determined is corrected according to the engine load variation rate. Thus, improvement of fuel consumption, reduction of the harmful components in exhaust gas are permitted, and acceleration and deceleration shock can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control method for an internal combustion engine, and more particularly to an air-fuel ratio control method that performs control by switching to either a stoichiometric air-fuel ratio or a lean air-fuel ratio depending on the operating state of the engine. This is related to improvements.

In recent years, with the deterioration of the energy situation and the tightening of exhaust gas regulations to prevent air pollution, research and development have been conducted on devices that can further improve the thermal efficiency of internal combustion engines and make exhaust gas cleaner. , one is available on the market.

One of them is the air-fuel ratio (△/l-), which is 15, which is sent to the engine.
62 people are known to raise the level of Nesdo and Park by controlling the weight pressure of the air and fuel in the air-fuel mixture to keep the self-harming components in the gas to a lower level.

In addition, the method of controlling the air-fuel ratio is not only controlled by the stoichiometric air-fuel ratio determined theoretically, but also by controlling the air-fuel ratio if the operating condition of the engine is within a specified range. A method has been proposed in which the air-fuel ratio is controlled by switching to a lean air-fuel ratio that has better thermal efficiency than the stoichiometric air-fuel ratio and has fewer self-harmful components in the 411 engine.

In addition, in such a method, the air-fuel ratio of 16f+U is set to a certain value, for example, 20, within a range that does not cause the engine to misfire, or it is set to a value that changes according to the engine's negative ratio. However, even if the air-fuel ratio is changed in response to the engine load, if the engine load is the same, the air-fuel ratio is controlled both when the engine is in the acceleration state and in the steady state.

J: Also, during acceleration, control using a lean air-fuel ratio will result in an insufficient output of -2-, so the output is insufficient, and the lift platform has a lean air-fuel ratio J,st] Liff(illill)
Automatically switches to the densest stoichiometric air-fuel ratio. J. It's being treated like a sea urchin.

Therefore, in the acceleration state 'c1.1. , air-fuel conversion from lean air-fuel ratio to lllll stoichiometric fuel ratio 1, k, I'l' il
The air-fuel ratio is frequently switched from l air-fuel ratio to lean air-fuel ratio λj), and the air-fuel ratio is switched at point X/+ in Figure 0 below.
Item 5: The torque changes as shown in point 1.#":'>
, 1. II V) Shock occurs at 1%.

In this case, from the point of view of drivability, it is preferable to use 1.t <↑, and in order to reduce the occurrence of this phenomenon, the 18 air-defense fuel ratio is lower than the optimal 1n. As a result of setting a slightly rich value of 1°, the thermal efficiency could not be sufficiently improved to improve the fuel efficiency of low 11. There is still one problem remaining.

The primary objective of the present invention is to provide an air-fuel ratio control method for an internal combustion engine that solves the problems 1)d(II+', 41).

The main purpose of the engine is to control the internal combustion engine by switching the air-fuel ratio to any one of the following: In the air-fuel ratio control method for an engine, the lean air-fuel ratio is set to a value corresponding to the load of the engine, and the value is applied to the above-mentioned -8 lean air-fuel ratio. This is achieved by an air-fuel ratio control method for an internal combustion engine that requires correction according to the engine load change rate.

The present invention will be explained below by giving examples and referring to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of an I5 twin engine to which the air-fuel ratio control method according to the present invention is applied.

In the figure, 1 indicates an engine (a3).The engine 1 has a cylinder block 2 and a cylinder head 3 on the right, and a cylinder tab has a tonk and a piston 4 is received in a cylinder bore formed inside the cylinder. The screw 1
A combustion chamber 5 is formed together with the cylinder head 3 on one side of the cylinder 4.

Cylinder head 3 has intake bow 1-〇 and υ1 air bow (~
7 are formed, and these boats are opened and closed by intake valve 8 and exhaust valve 9, respectively.
The spark plug 10 is attached to the cylinder head 3, which is located at 31. A current generated in the spark plug 10 is supplied to the distributor 12 and is discharged in the combustion chamber 5, causing a fire 1, 4 shots/1! J. The sea urchin is turning.

The intake boat 6 includes an intake hold 13, a surge tank 14, a suction body 15, an intake tube 16,
-)' No. 1-1 meter'17, ]-A-acrylic annular 1 are connected in this order, and the engine intake system has an
Bypassing the 1st 1-le body 15, the intake dicove 16
An air bypass passage '10 is installed to connect the air tank 17 and the air bypass passage 19.
is controlled by an electric ta type bypass flow rate control valve 20 to open and close the valve 1-1 degrees.

Further, a rigid air intake hold 21 and an exhaust pipe 22 are connected to the exhaust bow 1 to 7.

A 1,1 combustion nozzle/1 valve 23 is attached 1) near the connection end of the intake manifold 133 to each of the intake bows 1 to 6. The fuel is stored in the fuel tank 24 in the fuel injection valve 23)
Liquid fuel, such as gasoline, is supplied to the fuel pump 25.
The fuel is supplied via the fuel supply pipe 26.

S1] The amount of intake air is set for parts 1 to 15.
Ill! A throttle valve 27 is provided, and this throttle valve 27 is driven in response to depression of an accelerator pedal 28.

The air 70 meter 17 detects the flow rate of air flowing through the engine intake system and outputs a signal corresponding to the flow rate to the control unit 50.

Further, the distributor 1-12 has a built-in rotation speed tonk 29 that detects the rotation speed and rotation phase, in other words, the engine speed and crank angle, and the signal generated by this is input to the control device 50. It has become so.

IJI gas recirculation (FGR) passage 30 is an exhaust branch pipe 31
The exhaust gas recirculation valve 32 is connected to the exhaust gas tank 14, and the exhaust gas recirculation valve 32 is controlled by the exhaust gas recirculation valve 32 in response to electric pulses.
Change the aisle area. The exhaust gas recirculation valve 32 is controlled by the control device 150. cold 1. II Water temperature sensor 9-134 i; i Water temperature sensor 9-134 i;i Detects residual oxygen in IJ10,000 and outputs air/fuel signal Throttle 1 that detects the degree! Nri, :361.1. The intake air temperature detects the temperature of the intake air.

Next control υ11 device%! ') OL little one-C explanation J
Ru.

The control device M 50 I, 1 micro=] is an example of a control device shown in FIG. This microphone Dml player is sent to the central processing unit I (CPL).
J) 51, 1 and 11; Air-fuel ratio 11 and 11, etc.
The read memory 52 where the data is stored, and the memory 53 where the lamp data is stored. 11? +1. : If
b Maintaining memory through backup b
Random address memory 54 of depression, 1 to 51'1 including Δ/I) converters,
People who have eight power output boats! j6 and 4i11no,
These [31. It is directly connected to the common bus 57. This microcomputer~7-pico-controller is powered by a battery power source 37 as shown in Figure 1.
is supplied with an electric current, which causes it to operate.

Incoming capo-1-551; i, ■ Afrometer 17 occurs J
The intake air amount signal generated by the intake air temperature signal 36, the intake air temperature signal generated by the intake air temperature signal 36, and the engine cooling water temperature signal generated by the water recorder 3G are manually input, and these data are converted into △, /n and predetermined according to the instructions of the CPU 51. Cr P LJ at the time of
51 and random address memory 53 or 54.

In addition, for the engine output capos 1 to 56, the engine rotation speed No. 13 crank angle signal generated by the engine 29 and the air-fuel ratio signal generated by the 02 center 34 are input manually, and these data are sent to the CPU 51. CPU at specified timing according to instructions
51 and output to random address memory 53 or 54.

The bow is transferred to the fuel injection valve 23 via the output boat 56. Determined from the air amount and the rotational speed detected by the rotational speed sensor 2 [)]/, 21. The L control DI M is corrected according to the detected intake temperature 1α detected by the intake temperature sensor 36 and the engine cold IJI water shortage detected by the water temperature sensor υ33. ') 1', if the air-fuel ratio is controlled by the push wheel air-fuel ratio, 02 L? The CPU 51 feeds back the signal from the intake air temperature control 334 and makes corrections.The CPU 51 also adjusts the amount of bypass air during idling according to the intake air temperature detected by the intake air temperature control 36 and the cooling water temperature detected by the water temperature control 33. The signal is sent to the bypass flow control valve 20 via the output capos 1 to 56.
It is designed to output to. Bypass flow control valve 20
is from input/output boat 56! The degree of opening and opening 1α are determined according to the bypass air amount signal obtained.

In addition, CPU 511-L has started 1. T basic jet! ) J amount and rotation speed 1! The engine rotation speed and crank angle are detected in the engine 29, and the intake 111j
Based on the intake air temperature detected by 6, the R proper ignition time 1 times number is detected from the lead A rim 752, and this is detected from the input/output capo.
1-56 to output to the ignition coil 11.

Next, FIG. 3 shows the first actual M! of the present invention! 17-1 represents the control program Noro-f-17-1 applied to the air-fuel ratio control method of example i. The operation of this embodiment will be explained below along with this flowchart.

This program is interrupted as part of the main program for controlling the engine 1 or as a subroutine prior to predetermined fuel injection control processing.

When the processing of this program is started, in step 100, the intake air amount and the rotational speed sensor 1t29 to N are input from the air flow meter 17 through the input boat 55 and the input/output capo-56. Engine speed and water temperature sensor 9
59 to Tw] - Necessary data such as engine cooling water adjustment are input, these data are stored in a predetermined area in the random access memory 53, and the process proceeds to the next step 101.
-] 〇 - Transition to the process. .

STETSU 7101 i, - Hey ti, in the last program processing, 1) Expressed kQ/N, 1') engine load, and this time STETSU 7' 1 (1(') - C manual intake) Compare the air amount Q, engine rotation number NJ, and current engine negative/sensitivity Q/N sum 1. Set the increase/decrease in t as the engine load change rate △Q/N, and proceed to the next step 102.

In step 102 U 1.1. Based on the intake air 1iQ, the air excess ratio λ-1, i.e., I) is the fuel basic aI4II fjl ``I' +1 outputs 1 output (1 predetermined nozzle in the random access memory 53). In the next step 103, the current white level is stored based on data such as water temperature TW (read in step 100). It is determined whether 1 is in Article 4!1 or ti suitable for air-fuel ratio feedback (hereinafter abbreviated as 1/1) control, and it is determined that it is not in Article 1. If so, the processing shown in step 7104 is performed (line 1').

-11- In step 104, the basic injection amount Tp determined in step 102 is multiplied by the correction coefficient KO when no control is performed (1 in normal operating conditions). After calculating it T AU, the processing of the present program graph is terminated.

On the other hand, in step 103, engine 1
If it is determined that the condition fl is suitable for performing R1blJ in, the process moves to step 105, and condition A'1, which allows the air-fuel ratio to be reduced to 5111 parts by the M-engineered fuel ratio (lean air-fuel ratio), is satisfied. It is determined whether or not there is one, and if the determination result is rNOJ, the process moves to step 106 η.

In step 106, since the ordinance for controlling the air-fuel ratio in a lean state is not satisfied, a correction coefficient for the basic injection amount "1" for maintaining the air-fuel ratio at the stoichiometric air-fuel ratio,
That is, [-/B control coefficient "EΔ[ is calculated based on the output of the 02 sensor 34 read in step 100,"
The process moves to the next step 107 and is overwritten.

In step 107, the [/[3 curvature coefficient 1-ΔI: calculated in the previous step 106 is added to the kite book chanting To stored in a predetermined register in the random access memory 53. Actual performance IJ-1tri Find r△U l
After this, finish the wood block 1-1gram-1'-Jru, 1Meanwhile, step 10! If the condition 1'1, which can be controlled by the lean air-fuel ratio, is satisfied, the process immediately shifts to 1'L (step 10E).

In step 108, the graph as shown in FIG. Calculated from intake air amount Q and engine rotational speed N? *: i Based on Q/N,
Suitable for current engine square load Q,,,'N1. The set value of the lean coefficient K l corresponds to a provisional value that does not indicate a lean air-fuel ratio.
-1 is calculated.

Here, C will be explained with reference to FIG. Figure 4 shows the air-fuel ratio (△/IN on the vertical axis and the T engine load Q/N on the horizontal axis).
Table 1 shows the lean air-fuel ratio that changes according to the engine t''+6:+Q/N.
Kooi C S1-I1141, stoichiometric air fuel ratio Ho 11lr
i, and in the high angular range of graph 13, a hysteresis is provided for the purpose of preventing hunting when switching the air-fuel ratio.

Then, in step 108, the setting value K L 1 is calculated/
, m, in step 109, step 10
1. What is the change criterion for the engine load change rate ΔQ/N and the set value correction coefficient? What is the engine load change rate Δ (A indicates an acceleration state above a certain level) Which comparison judgment is made,
Judgment is l-No, 1. , that is, 15[ΔQ/N>Δ11. [
If so, the process immediately moves to step 110.

In step 110, since the second engine 1 is accelerating above a certain level and needs to be controlled with a slightly rich air-fuel ratio, it is multiplied by a relatively large set value correction coefficient KLB, and the product is the final set value ( <1-Finding, followed by step 112
to move to.

- In step J1 step 109, the determination is "rYFS",
That is, if "ΔQ/N≦A", the process moves to step 111.

In step 11, since it is in a gentle acceleration, steady state or deceleration state, in step-14-1゛10, J is relatively small. Multiply (^ to the final set value K l - doji, and proceed to step 1111 in step 112).

In step 1'12, the basic 11J in the register
'I set the final setting 1 (f K l to the p, set the optimal air-fuel ratio (l) to the actual nozzle of the I, and end this program. .

In this way, as a result of controlling the lean air-fuel ratio fJ, , J, -1 (when controlled, the L engine* '4F+ rate of change is Δ(:
)/'N is less than A, as shown by the one-dot chain line in Figure 55.
If N/l<8, then the solid line in the figure shows 1, and the air-fuel ratio becomes <7.

In other words, in this embodiment, the air-fuel ratio is determined based on the misfire range of the changing air-fuel ratio, or according to the degree of engine load iQ/N. As shown in 1, the load change rate ΔQ/N is ΔJ
, J, l, 11.1Δ or less), set the lean coefficient +ff K i 1 to i+ll 1l-iJ.
K l-13> knee 1h Replaced with one stage.

Conventionally, as shown in Fig. 6, when the lean air-fuel ratio at point X is in an acceleration state, that is, the engine load Q/N is increased, when the air-fuel ratio switches to the stoichiometric air-fuel ratio due to insufficient output, Y. The value is shown as a point. Therefore, the difference in output between point X and point Y (
When switching from point Y to point X, a shock of sudden speed increase occurred, and conversely, a shock of sudden deceleration occurred when switching from Y point to When controlled by the air-fuel ratio, fuel is injected so that the air-fuel ratio is close to a rich value, thereby eliminating the lack of output during acceleration and making it difficult to switch to the 1p stoichiometric air-fuel ratio. As a result, the shock that occurs when switching between 1 and 2 hours is eliminated.

Furthermore, even when the air-fuel ratio is suddenly switched to the stoichiometric air-fuel ratio in a state of acceleration, the shock is small because the difference between 1 and 1 lux is small.

In addition, since there is no need to set the air-fuel ratio to a lean air-fuel ratio in a steady state, and there is no need to adjust the air-fuel ratio to a value close to a rich one in consideration of the lack of output during acceleration, unlike in the past, it is possible to reach a lean air-fuel ratio that is suitable for a steady state. This makes it possible to achieve the original effect of lean air-fuel ratio control by improving fuel efficiency and reducing acidic components in υF gas.

In the 1711 embodiment described below, two sets of set value correction coefficients and l] are provided, 1<1-Δ, K1-1], but in order to perform more precise lean air-fuel ratio control. Set value correction coefficient to engine t'< M epidemic rate ΔQ/
The function binding determined by N is good. In the second embodiment described below, the set value correction coefficient is
The value of J- changes in Q/N.

FIG. 7 shows the control program of the second embodiment of the present invention1), so steps 200 to 203 and 205 to 2
Steps 10013 and 105 to 10 of the first embodiment described in 081
8 and 11, so the explanation will be omitted.

Now, in step 203, the condition f1 for satisfying the 1''/8 condition and performing lean air-fuel ratio control in step 205 is established.
If it is determined that 111 is satisfied, step 20
The process moves to step 8.

-17- In step 208, as in the first embodiment, the set value of the lean coefficient corresponding to the current engine load Q/N is set to 1-1, and the process moves to the next step 209.

In step 209, a linear function (1
+(80/N)g+(80/N) -a x (△Q
/N) 10b (a, b are constants) Or, quadratic function 92 of engine load change rate ΔQ/N
(ΔQ/N) (+2(ΔQ/N) -a -x (80/N)+b
The correction coefficient KLF is determined by 'x(ΔQ/N)0c (according to a-1b-1c is a constant), and the process proceeds to the first step.

Furthermore, the function g+(△Q/N > or !+2(ΔQ
/N) Approximately determined in accordance with the curve indicating the limit of the lean air-fuel ratio depending on the acceleration state.

In the next step 210, the correction coefficient Kl-F is set to -1.
8- Find with step number 208/,=setting 1+I'f K l
In step 211, the product is multiplied by 1, the product is finalized, and the process proceeds to the next step 211. Basic blowout collapse i
11, set the final set value KL obtained in step 7' 2 '10, and set the current [engine negative +:i] to l/N and the engine negative front change 5←△Q/N to immediately () Find the fuel corresponding to the air-fuel ratio (1.1 item 1△U and end this program.)
If 1 is not added, it becomes '1111i/;:<'r
(, "Proceed to step 204A, and in step 202, supplement 11 for correcting the basic jet q.1 suspension Tp.
Calculate & K o based on engine load Q/N,
The process moves to the next step 204B.

Sfutu 120413 smell-(, ^11 step 2
Correction coefficient 1 (0djJ book III!l) expanded in 04A
Multiply by the shooting height Tp, F/I'311. The actual injection IJ amount TAU of the lift platform where no II brightness is performed is determined and the processing of this program [1 gunm] is completed. In the first embodiment, the correction coefficient 1<() was set as a constant, for example, Ko=1, but in this embodiment, it is set as a value corresponding to the engine load Q/N. Actual injection amount 1-△ (J is being optimized when BlII God is not performed.

As shown in -1- below, since the correction coefficient that corrects the set value of the lean coefficient by 1-1 is changed according to the acceleration state, the empty air corresponding to the actual injection amount TAU is The fuel ratio is
As shown in FIG. 8, in a steady state, the air-fuel ratio is indicated by a solid line, α; in an acceleration state, the air-fuel ratio becomes, for example, a dashed line indicated by β, and in a deceleration state, the air-fuel ratio becomes t, L, for example, a If the air-fuel ratio is as shown by the dotted chain line, the air-fuel ratio will change according to the load change rate △Q/N, and even more precise lean air-fuel ratio control will be possible. It's like that.

In the embodiment described below, the engine load is expressed as Q/N and is explained as a 1 value. The basic suspension Tp,
Alternatively, volumetric efficiency ηV or the like may be used.

In case A, the rate of change is 8Tp and ΔηV is -20, respectively.
= Used.

Furthermore, in each of the embodiments (1, 1, 'd\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\, -) A ratio 1
For carburetor-type 1 engines that control the air-fuel ratio with 'l all, etc., the fuel adjustment hanging part has been changed] Jru1, f()C'
fV can easily apply the present invention.

More details! The method for controlling the air-fuel ratio of an internal combustion engine according to the present invention (in which the air-fuel ratio is controlled depending on the operating state of the internal combustion engine)
In an air-fuel ratio control method for an internal combustion engine in which the stoichiometric air-fuel ratio is controlled by switching to one of the rarest air-fuel ratios, -1
i nl'! Control 11 with J, -) to lean air-fuel ratio
When in an operating state in which It is characterized by

For this reason, the present invention improves the output irregularity caused by GJ in the acceleration state during lean air-fuel ratio control, and matches the engine characteristics.
By setting the air-fuel ratio to 1-11ν11, it is possible to improve fuel efficiency and reduce harmful components in the exhaust gas.

-21- According to the present invention, the lack of output in the acceleration state is improved, so it is possible to reduce the frequency of switching from the stoichiometric air-fuel ratio to the lean air-fuel ratio, or from the lean air-fuel ratio to the stoichiometric air-fuel ratio. , and since there is little output difference when switching,
It becomes possible to suppress both the frequency and magnitude of shocks that occur during the switching.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an internal combustion engine and its peripheral equipment in an embodiment to which the present invention is applied, Fig. 2 is a block diagram showing its control circuit, and Fig. 3 is a block diagram of the first embodiment. FIG. 4 is a flowchart showing the control program, FIG. 4 is a graph showing the relationship between the air-fuel ratio temporarily set in each embodiment and the engine load Q/N, and FIG. 5 is a graph explaining the operation of the first embodiment. , Figure 6 shows air-fuel ratio switching and output (torque)
FIG. 7 is a graph showing the control program of the second embodiment of the present invention. FIG. 8 is a graph explaining the operation of the second embodiment. 1...Engine (internal combustion engine) -22- 17...1 nonoso 11 meter 23...Fuel gauge q/1 valve 29...RPM E 33...Wood tone 1 pin 34...・02L! 50... Control strength 1N 51... c l) 1. J Sokujin Patent Attorney L Foot)l Tsutomu-23- Figure 4 ωN Q/N Figure 6 Go to Figure 8

Claims (1)

[Claims] In an air-fuel ratio control method for an internal combustion engine, which controls the air-fuel ratio by switching it to either a stoichiometric air-fuel ratio or a lean air-fuel ratio according to the operating state of the engine, when the operating state is such that control is performed using the lean air-fuel ratio, An air-fuel ratio control method for an internal combustion engine, characterized in that a lean air-fuel ratio is determined at a value corresponding to the load of the engine, and the determined value is corrected according to a rate of change in the load of the engine.