JPS631742A - Air-fuel ratio control method - Google Patents

Abstract

PURPOSE:To always control the air-fuel ratio with high accuracy by operating compensation quantity which increases and decreases the integration compensation value of the air-fuel ratio in response to specified operation condition in an engine operation area, and compensating basic fuel quantity based on said compensation quantity. CONSTITUTION:Upon operation of an engine 1, in a control unit 20, a compensation value K1 is first calculated according to the outputs of intake air temperature sensor 12 and a cooling water sensor 13, while an integrated compensation value K2 is increased or decreased according to the output of an air-fuel ratio sensor 14. Each engine condition compensation quantity is calculated by multiplying basic fuel ignition quantity by coefficients K1-K2 which are increased and decreased respectively according to said compensation value K2 at every respective operation conditions such as idle condition, normal operation condition and high load operation condition. The basic fuel injection quantity is calculated on the basis of outputs of an intake pressure sensor 11 and a rotation speed sensor 15. On the other hand, the basic fuel ignition quantity is compensated by engine compensation quantity and the like in each operation condition and is used as final injection quantity whereby a fuel injection valve 5 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an air-fuel ratio control method that detects an air-fuel ratio based on the exhaust components of an engine such as an automobile, and feedback-controls the air-fuel ratio of a mixture supplied to the engine to a predetermined air-fuel ratio based on this detection signal. Regarding the method.

The conventional air-fuel ratio control method integrates the output of the air-fuel ratio sensor,
It was simply integral control using this integrated signal. Therefore, during transient engine operation, if the basic air-fuel ratio changes faster than the correction speed of the integral control, the correction cannot catch up. Further, when the air-fuel ratio sensor is inactive, feedback control of the air-fuel ratio cannot be performed, and sufficient air-fuel ratio control cannot be performed, resulting in deterioration of exhaust gas. In other words, such a control method is good when the engine is operating in a relatively stable operating state, but it is difficult to learn in other acceleration ranges where a large amount of harmful exhaust gas components are emitted, so the correction speed of integral control is It cannot keep up with fluctuations in the basic air-fuel ratio, resulting in deterioration of exhaust gas. This problem is especially noticeable in fuel injection ψd, which programs the fuel supply amount using intake pipe pressure and rotational speed (see the margin below), and fuel injection system, which programs fuel supply amount using calibration valve opening and rotational speed.

Also, if you program with lll':Atsu pressure and rotational speed, to explain in more detail about fuel injection bagging, is the basic air-fuel ratio equal to v4 compared to the expected nitrogen-fuel ratio? The major causes of this are (1) variation in tappet clearance of the engine's suction νμ valve or production variations, 12) variation in injector raw material, oil pressure variation, (3) variation in atmospheric pressure ( For example, it was found that the errors due to these six factors differ depending on the conditions of the burial mounds 9) that are operated at high altitudes.

11) The error due to K is largest at idle, and becomes smaller as the intake pressure becomes larger in absolute value and as the rotation becomes easier.

The error due to factor (2) K is caused by operating conditions where the load is small (intake pressure is small).

1lfi, -% due to factor (3) has the same magnitude under any stray condition.

However, if errors due to three factors occur simultaneously, the error due to factor (1) is dominant in the idle state error, and the error due to the load A load 2! ! In the turning state, the factor (2
) is dominant, and in addition, with (6 loads and 4 payment widths), the difference due to factor (3) is dominant.
I made it clear.

The object of the present invention is to improve the air-fuel ratio (R division) method based on the output number 1 of the conventional desired fuel-fuel ratio sensor, and to reduce response delay even when the engine is in transients or peaks. Fuel ratio K flllJ dU ”C: Along with the colander, the air-fuel ratio sensor is inactive when the engine is at low temperature, so it is impossible to return to normal conditions. In the present invention, the output of the air-fuel sensor is divided into items 'a' and 'a'. 2. Gourd ratio correction? No need! A predetermined value for heating the sweetener? Do not directly correct the predetermined basic fuel injection amount from the compensation correction MLK that changes its upper and lower VC centering (first, in the engine operating range) For a predetermined operating state, that is, an idle state, a steady running normal load state d, and a steady running high load state, the Hffg compensation 4+R positive value is decreased or increased according to the determination of whether it is larger or smaller than the above-mentioned predetermined 1. Calculate each engine condition correction amount and add these engine condition correction amounts to the basic fuel injection amount to obtain the engine condition head correction injection amount.Next, the engine condition correction injection amount is The fuel injection site is paralyzed by the east line of the control correction 4, and this fuel injection failure is expressed. For, the integral (+fi positive(i
Is [is larger or smaller than a predetermined value? From this, the basic fuel injection 1tmK is set to 2 to the coefficient that decreases or increases around the predetermined base $1.
Multiply the pre-intake negative pressure and the engine speed by multiplying it by a coefficient (' f < Coefficient kl that decreases or adds 1 centering on 菟$
6 fuel 1' is calculated by multiplying withstand capacity, and for steady running high load pH, (depending on whether the contribution is larger or smaller than the predetermined value, the predetermined 2's ft!l (centered on iK) The f-correction amount is 1/3 for the coefficient that decreases or increases.

In addition, these correction Jl; 2. As for the predetermined engine operating conditions for the calculation of k and ni 3, when these coefficients are stored in the Kyoto Changling, the base air-fuel ratio mentioned above is incorrect for the 0 gradual air-fuel ratio! For each factor that produces a head, 4 tables are the largest 1) 4 VC and the factor's character 11: tl
l 1.141, and the sample time for the study is required once, so sometimes self-help employment engine: 4 Zeng, Idle or fixed as a learnable luck contagion, l? Although relatively stable conditions such as when driving are selected,
When making corrections during emergency situations, [is the most effective correction percentage 1t2. lcl
Corrections according to and 3 are performed. Therefore, for example, in the tiddle state, the correction amount is calculated by the recent coefficients stored in addition to 2 and 3 for the coefficients calculated in that state and directly reflecting the situation, and the constant fi52 line is normally In the loaded state, in addition to the coefficients calculated in that state, the NFL's recent idle body moving into that state and running at a constant rate, <@ @ @ the coefficient calculated in the unloading class, is Using 2 and 3, a total of 4 engine state corrections are made. ◎Therefore, the engine operating state is one state! ,! 1
Even if the temperature changes from 1 to other cold temperatures, the overall correction amount will not change suddenly, and the engine will maintain smooth operation, and the response will be delayed even when the engine is running smoothly or when A marks occur. It is possible to correct 1llll'llllI41 without any correction. Also, 2.
Since the coefficients k and 3 are stored in the memory device, even if the air-fuel ratio sensor in 2 is inactive when the engine is at a low temperature, they are stored.The coefficients in 2 can be used to create a return leg with a 12P% ratio.

In addition, among the engine condition j order correction amounts, the idle reserve j net correct amount uses a coefficient C that is inversely proportional to the intake pipe pressure and rotation speed at the same time as 2 for #AI2, so the correction amount in the claw area where rotation and load are high is Since it is smaller, it is possible to supply pressure in response to changes in tappet clearance.

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

An engine 1 shown at 2 in FIG. 1 is a known four-stroke spark ignition type 1 engine mounted on an automobile, and intakes combustion air through an air cleaner 2, an intake pipe 3, and a throttle valve 4.

Further, fuel is supplied from a fuel system (not shown) through magnetic fuel injection valves 5 provided corresponding to each cylinder. The exhaust gas after combustion and phosphorus is released into the atmosphere through the exhaust manifold 6, the exhaust gas 177, and the three-way catalytic converter 8.
1 (Detected by the intake air/a pressure sensor. The pressure sensor outputs an analog voltage signal. In addition, the intake air/a3 is input to the engine! 2!''A intake air sensor 12 that detects the temperature The engine engine 1 is equipped with a water temperature sensor 13 that detects the cooling water temperature.Furthermore, the ηF air manifold 6 is equipped with an air-fuel ratio sensor based on the acid concentration in the exhaust gas, and the air-fuel ratio is smaller than the stoichiometric air-fuel ratio. (rich) and about 1 volt (IaJ level), the air-fuel ratio is 0.171 volts, and the air-fuel ratio is 0.171 volts (IaJ level). It is [there].

The rotational speed sensor 15 detects the rotational speed of the crankshaft of the engine 1 and outputs a pulse signal with a frequency corresponding to the rotation jK degrees. Tll1l@XI unit 20 has each sensor 1
By controlling the opening time of the electromagnetic fuel injection valve 5 using a circuit that calculates fuel injection based on the starting signals 1 to 15, fuel injection is performed as a shrine.

The 1b Lee unit 20 will be explained in detail with reference to FIG.

100 is a microprocessor (C
PU). Reference numeral 101 is a number counter A which counts the number of engine rotations based on a signal from the rotation speed sensor 15. Further, this rotation/collection counter 101 sends mowing control tllEG 102K/mowing command No. 16 in synchronization with the engine rotation. When the interrupt processor 102 receives this number 1g, it interrupts the microprocessor 100 through the common bus 150.
((Output the subsumed bond.

Reference numeral 103 is a digital input boat, which is the output of the air-fuel ratio sensor 14 which is compared with a predetermined comparison level. 104 is an analog input port consisting of an analog multiplexer and an A-D converter, which transmits the !?+1 bar from the Ia tracheal pressure sensor 11, intake air temperature sensor 12, and cooling water temperature sensor 13 to A- It has the function of converting the data into D and inserting it into the 4th order microprocessor 100.
02,103. IU4 output information is common path 1501
idl and transmitted to the microprocessor 100.
105 is RAM IQ 7, which will be described later in the IJL extraction circuit.
dt source. 11 is a battery, 18 is a key switch, and ta1! ! 1wIt105 kl dt
- 3Hb directly to battery 1γ without passing through switch 18
)R has been done. Therefore, the RAM 107, which will be described later, is
There is no 1A for the switch 18 (l''fl is always applied).

106 is also a power supply circuit, but it is connected to the battery 17 through the switch 1B. The ridge source circuit 106 supplies a partial TCT source other than the RAM 107, which will be described later. 1
07 is the 14th Kiku Units (RAM) used when the Dakugu 2 is in operation, but as mentioned above, the key switch 1
Regardless of 8, 'U time frame is 19 mouths and key switch 1
It is an F4 configuration in which the contents of the RID do not disappear even if the engine is stopped for one rotation at 8t toy F, making it a non-rA older memory. # k2 according to the engine-like coarse positive coefficient described later
1 k3 is also stored in this lake 10γ.

10B is a program? 109 is a memo for starting the fuel injection time (ROM).109 is a kakunta for controlling the fuel injection time including a register, which is used for down-counting, and a microphone calculation processor (CPU) 1
The opening time of the electromagnetic injector 5, that is, the fuel injection amount calculated by tX at 00, is converted into a pulse signal with a pulse duration that gives the actual opening time of the 4-magnetic fuel injector 5. Convert.

What about 110? l! This is a tortoise force amplifying part that drives the magnetic fuel injection valve 5. 111 is a timer that measures the running time of CPU 1
It's low to 00. The times % generates an interrupt signal from that signal, and causes the microprocessor 100KNpS to execute an interrupt processing routine for calculating the fuel injection amount.

The 31st threshold shows a schematic flowchart of the microcomputer computer 100, and this 7c! - f52t on chart
4 of 100 microcomputers: @Noze explains. When the key switch 18 and the starter switch 16 are turned on and the engine is started, the first step 10 start r [and the main routine's itch treatment is started. /7 periodization processing is executed, and in step 1002, the digital values corresponding to the cooling water temperature and intake air temperature from the analog input capacitor 104 are incorporated into e.

In step 1003, 1 is calculated as a correction value by the well-known Nobi 4 formula based on the results of the 4 results, and the s4 dye is stored in the RAM 107. In step 1004, the signal from the fuel-fuel ratio sensor 14 is input from the digital human-powered boat, and the elapsed time determined by the timer 111 is subtracted by the amount of time (described later), and this correction (Poni 2 RAM I 7 K, stored.The 4th IA is a detailed flowchart of the processing step 1P1004 that increases or decreases this integral correction value by 2, that is, integrates it.In step f400, the air-fuel ratio is detected?
Check whether J is deactivated or cooling water Lj
, from the 1st place, it is determined whether or not the return 1111 prisoners can be taken, and when the death j1 cannot be determined, the power of the open loop goes to Stella 7° 406, and the correction is 19, 2 is 2 = 1, and Stella is 7'40 Stζjlm. Return! If you can use II Gri, go to 2ttsu f401. In step 401, it is measured whether the elapsed time has passed the unit time Δt1, and if it has not passed, the process step 1004
to be exterminated. If the time Δt has passed, the process advances to step 4Q2, and if the air-fuel ratio is rich and the output of the air-fuel ratio sensor 14 is rich (high level No. 18), step 41:13KA is executed. 2 for what I asked for in the previous cycle?
: Decrease Δ by 2, go to step 405; Escape, new correction value Kg? :RA) Store in J107. In step 402, if the air-fuel ratio is lean and the output of the air-fuel ratio sensor 14 is a low level 16 indicating lean, the process proceeds to step 404, where Δ is increased by 2, and the process proceeds to step 405. In this way, the correction value x2 is increased or decreased.

The integral correction value 2 thus changes above and below the predetermined K, which represents the state d in which air-fuel ratio correction is desired.

At step 1005 in the diagram r, g3, the engine condition correction value k2. Calculate k3 by increasing or decreasing tlIi and store Kinumi in 10T.

Figure 5 shows coefficients □ and 2. k and s are @ear processed and stored. In other words, this is a detailed flowchart of step 1005 for storage processing.

In step 501, it is measured whether the elapsed time has passed the Rin'i time Δt2, and if Δt2 has not passed, write 1.1! Processing process ends. If the elapsed time has elapsed, the process advances to step 502, and the rotation speed N, which is taken into consideration in the RAM 107, is
@Air pressure C pressure is in idle state L4m listed in Tatsuwa-cho
Conditions (600<N<90 Orpm, 200<P
<400 mwrHg)? 44J is different.

When the ridge arrangement condition is satisfied, 7A is applied to the stellar f5θ3, and a value of 2 is determined as the integral correction value. K2; If it is 1, do not do any number,
This processing Stella 7#1°005 ends.

If 2>1 in step 503, the process proceeds to step 504, and if K2<1, the process proceeds to step 505.

In Stella f50, 4, 505, 2 is added to 2rCΔ and 4 or subtracted 74 times to the coefficient, and in step 506, the accumulated 2 is stored in RAM i 07, and step 1005
1h: Finish.

In step 502, if the 4d relative condition t is n, it is interrupted in step 507, and the rotation speed N is steady running.
400-6000 rpm! Lii! If it is not in this area, in step 1005 +dj
Terminates without processing. #1 of 1400~6U00rpm
When it is within the range of 250 to 400 mpnHg, the intake pipe pressure P passes through the Stella F508 and absorbs the V load.If it is within the above range, proceed to step 509. When the intake pipe pressure P is not within the range of 250 to 400 mn*E4g, proceed to step 513 and further increase the pressure P to 400 to 650 mn*Hg f.
) Determine whether it is within the range.

If it is not in the upper ad, do not process Fl, and perform this step i.
o”as ends.

In step 509, a value of 2 is determined as the integral correction value.

If K2=1, this processing step 1005 is ended without any exception.

If K,>1, proceed to step 510; if K2<1, proceed to Stella 21''511. Stella 7P510°5
In step 11, 3 is added to the coefficient and 3 is added to Δ, and in step 512, 3 is added to the newly obtained coefficient. ■ 4f is added to 107.
fi, and the step 1005χ ends.

1&q'8 When the pressure P is between 400 and 65 Q *mJLg, proceed to step 514 and integrate? +fl positive value 2
Determine the size of the bag.

If K2=1, it can be defeated, this processing step 1005χ
, 5) Complete.

K2> 1 f) t'g hass f t f 515! Mi, K
If 2<1, 1A is sent to step 516. Step 51
5゜516, the coefficient is Δkl and 0 swords or subtraction f1
Process and R to the newly found coefficient in Stella 7p517.
pat 107 and ends step 1005.

Normally, the main routine processing from 1002 to 1005 is repeated in X lines according to the control program. When the vA9-inclusive code of the fuel injection operation 4 is input from the U section 102, the microcomputer 100 immediately interrupts the main routine even if it is in the middle of processing the main routine and returns to step 1010. 6. Move to the interrupt processing routine. stella f1
At step 011, the engine rotational speed N is taken in from the rotational speed counter 101, and at step 1012, the 1st number that eliminates the 1&a pressure P is taken in from the analog input capo) 104. (In step 1013, the rotation speed N and the pressure P are stored in the RAM 1 [37] for use in the anti-pruritic treatment of the main routine.

Next, in step 1014, RO! , (1Q
3 circle engine 1g 1 rotation number N and intake pipe pressure P 2 arrows of Mazda
Find Kawahin by tlf1 interval. Next step 10
15 in the Flea Emain Routine) ・Unit for direct firing, ・Injection t to determine the air-fuel ratio read from RAM 107 and correction coefficient of electricity ("R injection time width")
Perform the correction lff paralysis. Injection time width TI) 8t'-
Equation 4 is T = ((1 + cl + m2 honor c) aTp + 3
) Masu is 0 and Homare is 2.

As can be seen from this equation, (1 + kl + 2 C) soup Tν + 3 is calculated by six correction amounts α, k2. Based on k3, tt
, the engine condition correction amount Y is added to the basic injection amount, and among these, □Tp is the steady λ traverse load condition correction failure t, k2 Hakama C Homare Tp is the idle 3 is the normal load correction company for regular running. Then, in step 1016tC, data of heavy pressure 1t$t and fuel injection iT are set in the kakunta 109.

Next, Stella 7'1017KaA returns to the main routine. When returning to the main routine, the process returns to the processing step at which it was interrupted due to interrupt processing. microprocessor 10
The general function of 0 is as above.

As described above, the engine condition correction amount is divided into three coefficients,
, , , , etc. Therefore, deviations in the basic air-fuel ratio in each operation mode caused by various factors can be finely corrected.

Furthermore, since +, kz, and ks are all learned only under idle or stable operating conditions, and correction is performed over the entire range, it is possible to appropriately correct the acceleration/deceleration range that cannot be learned.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an apparatus for explaining the present invention in detail, FIG. 2 is a block diagram of the control circuit shown in FIG. 1, and FIG.
This figure is a schematic flowchart of the microprocessor shown in FIG. 2, FIG. 4 is a detailed flowchart of step 1004 shown in FIG. 3, and FIG. 5 is a detailed flowchart of step 1004 shown in FIG. 3.
05 is shown in detail. DESCRIPTION OF SYMBOLS 1... Engine, 5... Fuel injection valve, 11... Intake pressure sensor, 14... Air-fuel ratio sensor, 15... Rotational speed sensor, 20... Control unit.

Claims (1)

[Scope of Claims] A method comprising an air-fuel ratio sensor that detects an air-fuel ratio based on engine exhaust gas components, and controlling the air-fuel ratio of a mixture supplied to the engine to a predetermined air-fuel ratio based on a signal from the air-fuel ratio sensor. Then, calculate the first correction value by integrating the signal from the air-fuel ratio sensor, and calculate the first correction value for three of the idle state, normal load operating state, and high load operating state.
Each engine state correction value is calculated based on the first correction value for each engine operating state, and updated and stored in a storage device, and the basic fuel amount to the engine is updated and stored in the idle state of the engine. The state correction value and the engine state correction value updated and stored in the normal load state are multiplicatively corrected, and the engine state correction value updated and stored in the high load state is further corrected additively, and the corrected fuel is An air-fuel ratio control method, characterized in that the air-fuel ratio is supplied to the engine.