JPS6045744A - Fuel controller for engine - Google Patents

Abstract

PURPOSE:To exactly control fuel at the high ratio of the fuel to air, without being affected by secondary air, by using an engine condition compensation value as basic data to calculate an engine condition compensation value at the high ratio of the fuel to the air. CONSTITUTION:An injected quantity is instructed to an injector 8 for injecting fuel into an intake passage 7 downstream to an air cleaner 6. Air sucked through the air cleaner 6 is pressurized by an air pump 9. The energizing and de-energizing of a solenoid valve 12 for secondary air control, which is provided in a passage 11 for supplying secondary air to the upstream part of the exhaust passage 10 of an engine E, are controlled by a microcomputer 5, which receives the output signals from a negative pressure sensor 13, a rotation sensor 15, an O2 sensor 1, an intake temperature sensor 17 and a water temperature sensor 18 to calculate an engine condition compensation value at the high ratio of fuel to air to perform the open-loop control of the ratio on the basis of the compensation value.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention controls fuel by using the output of an engine fuel control device, particularly an air-fuel ratio sensor such as an 02 sensor, as a feed bite signal, and learns the control results. The present invention relates to a fuel control device for an engine in which the learned value is stored as a value, and the next fuel control is started based on the learned value.

(Prior Art) A so-called learning control method has been proposed in order to improve the responsiveness of fuel control during transient engine operation in order to deal with so-called aging of engines and variations in performance among individual engines. This learning control method for fuel control uses the 02 sensor installed in the engine's exhaust system.
After determining whether the air-fuel ratio is correctly controlled to the stoichiometric air-fuel ratio from moment to moment, the fuel amount is feedback-controlled based on the output signal of the 02 sensor, and basically the intake negative pressure (engine load) and engine speed are controlled. The correct fuel amount for each operating zone of the engine, which is determined by the number, is learned (memorized) in advance at an appropriate timing by sampling, and when the operating condition changes, the learned value corresponding to the changed operating zone is read out. Therefore, the current fuel control is performed based on this learned value (Japanese Patent Laid-Open No. 55
(Refer to Publication No.-96339).

However, this learning control method only uses the 02 sensor to determine whether the control is correct or not, or whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio, so it is not possible to operate with the air-fuel ratio enriched. In the case of high-load operation of the engine (Ij) (so-called enrich zone), it is possible to determine whether the air-fuel ratio is rich, but it is not possible to determine whether the fuel is appropriate.

Therefore, in the conventional learning control method, in the high load operating range,
Currently, open-loop control is used, and fixed map control that is preset according to the operating state is performed.

In view of the current situation, the applicant of this application has filed a patent application filed in 1983-16.
In the patent application No. 1.698 (title of the invention ``Fuel control device for engines''), the values learned during closed-loop air-fuel ratio control are applied to various high-load operating ranges during open-loop air-fuel ratio control. We are proposing an engine fuel control device that can realize optimal control of fuel (air-fuel ratio) that takes into account aging and variations in the engine over the entire operating range of the engine by reflecting this in the fuel control of the operating state. .

(Object of the Invention) The present invention has been made based on the above-mentioned proposed invention, and provides two cases in which secondary air for purifying exhaust gas is supplied to the exhaust system of an engine even under the same operating condition. This method focuses on the fact that the engine condition correction value is different when the secondary air supply is stopped, that is, when the secondary air is cut.

In other words, in the operating range (feedback zone) where closed-loop control of the air-fuel ratio is performed, secondary air is normally supplied to the engine exhaust system, and the exhaust gas purification device, such as a catalyst type, installed in the exhaust passage is used to reduce the amount of exhaust gas contained in the exhaust gas. The unfired component is purified by reacting with oxygen in the secondary air. On the other hand, in the high-load operating range (enrich zone) where open-loop control is performed, the air-fuel ratio is set to the lean side to ensure high engine output, and the amount of exhaust gas also increases compared to the closed-loop control operating range. Therefore, when secondary air is supplied to the exhaust system, there is a problem in that the reaction heat generated in the exhaust power oceanicating device becomes excessive, leading to thermal deterioration of the catalyst and the like. Therefore, in the high load operating range where open loop cutoff 1 is performed, secondary air is usually cut.

Now, considering the case where secondary air is being supplied,
In this case, oxygen contained in the secondary air greatly affects the output of the 02 sensor provided in the exhaust system. Actually, 2
The next air supply position is relative to the 02 sensor setting position.
In the downstream direction of the exhaust gas, it may be upstream or downstream, but even in the downstream case, a part of the secondary air flows back to the 02 sensor position due to so-called exhaust pulsation.
The output of the 02 sensor will be affected by it. On the other hand, during operation in which the secondary air is cut, the output of the 02 sensor is naturally not affected by the secondary air.

In other words, for example, even if the operating conditions of the ennon specified by the intake negative pressure and engine speed are the same, two
The feedback signal that is the output of the 02 sensor differs between when the next air is supplied and when it is cut, and shows a small value. Therefore, it is extremely difficult to use the engine condition correction value obtained during closed-loop control that supplies secondary air as the basic data for setting the engine condition correction value during open-loop control that cuts secondary air. This is not preferable because it will include a large amount of error.

The present invention specifically aims to solve this problem, and when calculating the ennon state correction value during open loop control (enrich zone) where the supply of secondary air is stopped, closed loop During control, with the secondary air cut, calculate the engine condition correction value during closed-loop control, and use the engine condition correction value in the feed bank zone with the secondary air cut as basic data to calculate the engine condition correction value in the enrich zone. It is an object of the present invention to provide a fuel control device for an engine that calculates an engine state correction value.

(Structure of the Invention) Therefore, the present invention provides the following features in the feedback zone:
The engine condition correction value is learned with the secondary air supply and the secondary air cut, and the engine condition correction value in the enrich zone is calculated using the learned value (engine condition correction value) when the secondary air supply is stopped. Based on this engine condition correction value, open-loop control of the air-fuel ratio is executed.

As shown in the block diagram of the invention in FIG. 1, the present invention includes an air-fuel ratio sensor 1 that outputs a signal corresponding to the air-fuel ratio of the air-fuel mixture taken into Ennon E, and an operating state sensor that detects the engine operating state. 2, a first storage device 3 in which a basic control value for controlling the air-fuel ratio of the air-fuel mixture taken into the engine is given in advance in accordance with the engine operating state; and a first storage device 3 for correcting the basic control value. a second storage device 4 that stores ennon state correction values corresponding to each engine operating state; and during closed-loop air-fuel ratio control, calculates an air-fuel ratio correction value based on the output signal of the air-fuel ratio sensor, and processes the air-fuel ratio correction value. and update the engine state correction value corresponding to the engine operating state at the time of processing in the second storage device 4, and update the engine state correction value corresponding to the engine operating state at the time of processing in the second storage device 4. An air-fuel ratio correction value is determined based on the signal of the fuel ratio sensor 1, and an engine condition correction value during open-loop air-fuel ratio control and secondary air cut is determined based on the engine condition correction value obtained by processing the air-fuel ratio correction value. The engine state correction value is stored in the second storage device 4 at the time of open loop air-fuel ratio control and
The basic control value in the first storage device 3, the engine condition correction value stored in the pIS2 storage device 4, and the air-fuel ratio sensor 1 are stored in correspondence with the engine operating state at the time of the next air cut.
This is a fuel control device for an engine, which includes a control device 5 that controls the air-fuel ratio of the air-fuel mixture taken into the engine based on an air-fuel ratio correction value obtained based on an output signal of the air-fuel ratio correction value.

(Effects of the Invention) According to the present invention, during closed-loop control in the feedback zone, the engine condition correction value is set with the secondary air being cut, and the engine condition correction value thus set is used as the basic data. Since the engine condition correction value in the enrich zone is calculated as follows, the engine condition correction value obtained in a state that is close to the operating condition of the enrich zone without being influenced by secondary air is calculated as the engine condition correction value in the enrich zone (fee 1' The more accurate the fuel control in the enrichment zone, the more accurate the fuel control in the enrichment zone.

(Example) Examples of the present invention will be described in more detail below.

As shown in FIG. 2, the fuel control system for the engine E according to the present invention is installed in the intake passage 7 downstream of the air cleaner 6).
A secondary air supply passage which instructs the discharge amount to the innojector 8 that injects the heating charge, pressurizes the air sucked in through the air cleaner 6 with the air pump 9, and supplies it as secondary air to the upstream of the exhaust passage 10 of the engine E. Turn on the electromagnetically actuated secondary air control valve 12 installed in the coil 1.

It basically consists of a microcomputer 5 as a control device for controlling off, and the following sensors that provide various data necessary to this microcomputer 5.

Negative pressure sensor 13...Detects the intake negative pressure downstream of the throttle valve 14 in the intake passage 7.

Rotation sensor 15...Detects the rotation speed of the engine E. This rotation sensor 15 together with the negative pressure sensor 13 constitutes the operating state sensor 2 according to the present invention.

02 sensor 1...Engine E exhaust passage 10
The air-fuel ratio of the air-fuel mixture taken into the engine E is detected from the oxygen concentration in the exhaust gas, whether the air-fuel ratio is rich or lean.

Intake temperature sensor 17...Detects the temperature of intake air.

Water temperature sensor 18...Detects the cooling water temperature of the engine cooling water passage 19.

As shown in FIG.
5, 17. Input the output of 18, or injector 8
and an I10 ink face 20 for outputting commands to the secondary air control valve 12, a central processing unit (CPU) 21, and a read-only memory (RO).
M) 22, random access memory (RAM) 23
These are connected to a data bus 24 and an address bus 2.
It has a basic structure connected by 5.

Each address of the read-only memory 22 is stored in each engine operating state specified by the engine speed r and the intake negative pressure.More specifically, as shown in FIG. Negative pressure ■-V,・V2. V3. Engine operating states Z 1 to zl defined by the curve V
o, zA to ZC, and each corresponding @ field indicates the basic fuel discharge amount Q'(r.

2) is stored in advance to create a basic control map, and a part of this read-only memory 22 is used as the first storage device 3 according to the present invention.

Similarly, each address in the random access memory 23 corresponds to each engine operating state specified by the engine speed r and the intake negative pressure, and the corresponding address contains an engine state correction value, which will be explained in detail below. 3 is stored as a learning value in an updatable manner, and a part of this random access memory 23 is used as the second storage location 4 referred to in the invention.

Then, the CPU 2 of the microcomputer 5 is stopped.
As shown in the flowchart in the figure, it is determined that the pulse is in progress during the execution of the main routine. Then, the pulse is outputted by an interrupt signal during execution of the main routine.

This fuel control routine starts with I10 by the start signal.
After initializing the interface 20 and necessary data, execute step 7 below and repeat this.

In Step], the rotation sensor 15, the negative pressure sensor 13, the water temperature sensor 18, the intake temperature sensor 17 and ○, the sensor 1, the engine rotation speed r, the intake negative pressure -■, the cooling water temperature θ, the intake temperature θa and the 02 sensor signal P to I/6 Inter 7
Load via Aku20.

In step 2, the engine operating state at that point is detected from the read engine speed r and intake negative pressure V,
The basic discharge amount Q'(
r, V) is read from the basic control map of the device 3 to the first entry.

Next, in step 3, (θ, θa) is calculated as a temperature correction coefficient for the basic discharge amount Q′ based on the read cooling water temperature θ and intake temperature θa.

Calculation of 1 for this temperature correction coefficient can be performed using the map as described above, but it is also possible to use a formula without using the map. In any case, when the cooling water temperature θa is low, or when the intake air temperature θa is low and cold, the temperature correction coefficient is set to a larger value of 1 than during normal operation.

Furthermore, in step 4, an air-fuel ratio correction value of 2 is calculated based on the o22 sensor signal P.

This air-fuel ratio correction value is 2, for example, the previous 02 sensor 1
If the output signal P is lean and the current output signal P is also lean, the increase amount Δ is calculated as 2 so that the discharge amount is increased by an appropriate amount from the previous discharge amount, and the previous air-fuel ratio is The correction value is set to the value obtained by adding 2 to the increase amount Δ calculated in ← as 2+Δ as 2. Also, when the output signal J:fP reverses from lean to rich, it is considered that the previous discharge amount was too large, so the current reduction amount △IK2 is calculated based on the previous air-fuel ratio correction value and 2, and this time The air-fuel ratio correction value of is set as 2←2-Δ'2.

Conversely, if the previous output signal P was rich and the current output signal P is also rich, 2 is calculated for the j component △゛ and the current air-fuel ratio correction value is 2←. −△゛′ to 2
In this case, the increase amount ΔIIIK2 is calculated and the current air-fuel ratio correction value is set to 2+Δ+nK2.

Note that the air-fuel ratio correction value 2 is a constant value, that is, 22, during open-loop control, that is, in the high-load operating range of Ennon (the operating range shown with diagonal lines in Fig. 5, hereinafter referred to as the enriched zone). Set to 1.

In the next step 5, an engine condition correction value of 3 corresponding to each engine operating condition is calculated based on the air-fuel ratio correction value of 1 and 2.

This calculation (learning) of the Ennon state correction value 1<,
Follow the flowchart shown in the figure.

A detailed explanation will be given below with reference to FIG.

In step 501, at the start of learning, if 3 is learned with the supply of secondary air stopped, the learning state value IF is set to "1", and otherwise takes "0". Next, determine whether the engine is in the operating zone based on the engine speed r and the intake negative pressure V.As shown in Figure 6, if the engine is in the operating zone, the Enrich zones z A, z indicated by diagonal lines as feedback zones zl, ..., ZIO for each engine operating state specified by the engine speed r and intake negative pressure V (excluding acceleration/deceleration operating ranges). The engine speed r that was divided into B, z and C and read in step 1
And from the intake negative pressure V, it is determined to which zone the current engine operating state belongs.

The feedback zones Z1 to zloi: k, 02 are zones that perform learning control based on the output signal P of the sensor 1, that is, closed loop control, and these zones t'li, t, and the secondary air control valve 12 are While maintaining this state, 2* air supplied by the air pump 9 is supplied to the exhaust passage 10 via the secondary air supply passage 11 to purify the exhaust gas going up to the catalyst device 16. On the other hand, enrich zones ZA, z B, and z C are open-loop control zones corresponding to the high-load operating range of engine E, i.e., ○, sensor 1
The air-fuel ratio of the air-fuel mixture is controlled to be richer than the stoichiometric air-fuel ratio, and the secondary air is cut in this zone and the air-fuel ratio of the catalytic converter 16 is controlled based on the output signal P of the air-fuel mixture. Prevents thermal deterioration.

Next, in step 7 step 502, it is determined whether it belongs to the determined zone 10 or the enriched zone zA, zB+zC, and the enriched zone ZA+zBH
If any of zC is, for example, ZA, step 5
At step 29, 3 (zA) is read out as the previous engine condition correction value stored in the second storage device 4, and this is discharged a! It is used as a correction value for the I quantity Q.

In steps 503 and 504, it is determined whether the engine is in acceleration/deceleration operation or not, and whether it is in cold engine operation, and in step 505, if the operating state belongs to the feed bank zone, the enrich zone zA-zC is selected. It is determined whether the adjacent fee belongs to any of the hack zones 28.z9+210.

(I)Z 8. z 9. z If the feedback zone is other than 10 (low 21 to 7.7), in this case, the process moves to step 51G and basically steps 5
The sampling of the air-fuel ratio correction value is performed by repeating the routine from 16 to 529.

3 is calculated as the engine state correction value through learning.

In other words, when the number of sample links reaches 1 power and 28,
Set I=O, k=O (k is the sum of 2) and (
Step 517), every time the output signal P of the 02 sensor 1 inverts from rich to lean or from lean to rich, sampling (see Figure 7) is performed and 2 is added to the air-fuel ratio correction value at that time (step 517). , Pu 518. 519
). When the number of Sambli jigs 1 reaches 11811, after confirming that I F = 0, in step 528, according to the following formula, 3 (beats) is added to the Ennon state correction value.
I put it on.

Note that K,'(m) is the previous engine state correction value currently stored in the second storage device 4, and α is a constant smaller than 1.

Add 3([n) to the engine condition correction value determined in this way.
is read into the corresponding address of the second storage device 4 in step 528, and 3' (+n) is added to the previous engine condition correction value.
Replace 3(m) with the engine condition correction value found this time.

(II) Feedback zone 28. Z9 or 210 In this case, for example, after the transition to feedback zone Z8, learning during secondary air supply, learning with secondary air supply temporarily stopped, secondary air The N13 stage of learning is performed by restarting the supply of .

That is, as shown in FIG.
Let T be the time from the time when the transition to IJI t,i is reached at the first setting, which is set appropriately in advance.
The supply of secondary air is continued, and then the supply of secondary air is temporarily stopped from the first set time t1 until the second set time opening t2, which is set in consideration of the transition time, reaches the third set time t3. Learning is performed according to a time chart in which the secondary air is stopped and the supply of secondary air is restarted after the third set time L3.

Note that in FIG. 8, L is a fourth set time t, which is preset as a transition time when the supply of secondary air is restarted.

The learning at each stage above will be explained below.

(II) -1T<t, (when secondary air is supplied) In this case, sampling is performed in the same manner as described above in steps 516 to 529 until T reaches the first set time (step 514). Feedback zone z8. z9. 3 (z8) for the engine operating condition correction value when supplying secondary air, 3 (z 9) for zlO,
, calculate 3 (210). That is, as mentioned above,
In each feedback zone 7-8.29 or zlo, 0. Every time the output signal P of sensor 1 inverts, 2 is added to the air-fuel ratio correction value, and after confirming that secondary air is being supplied, in step 528, (m ), and the memory at the corresponding address in the second storage device 4 is updated in step 528. (II) If -2t2≦T<t, (at the time of secondary air cant), first, the time T is changed to the first set time t1. When it reaches, the number of sampling times ■
, add the added value k to "°0".

Then, in the path of steps 507, 508, and 509,
When tl<T<t2, a secondary air stop command is output in step 510 to temporarily stop the supply of secondary air.

The second cut of the secondary air is performed by applying an off signal to the secondary air control valve 12 shown in FIG. 2 to shut off the secondary air supply passage 1.

Next, in step 511, 1 (z 8) is set as the Ennon state correction value in the transition period by interpolation calculation. That is, the latest Ennon state correction value at T<t is 3(y, 8
) is Q, and T2 is the previous engine state correction value at 3'(z 8 ) is Q2, then the transition period (
t,<T<L2), the engine condition correction value at
(28) is determined by the following equation.

This ', (z8) is used as a correction value for the discharge amount Q during the transition period.

Next, when the time T becomes equal to or longer than the second set time t2, steps 50g, 512. 513, the engine condition correction value layer (z8
) to learn. That is, when Tit2 is reached, the supply of secondary air is stopped in step 512 so as to continue to step 510, and the state function IP is set to 1 in step 513.
At this point, we move on to learning with the secondary air stopped.

In this learning, as described above, 2 is sampled and sequentially added to the air-fuel ratio correction value as an extreme value for each Lean-Lynch reversal, and when the number of samplings reaches "8" (step 520), the state function Since the IP is not 0, the process moves to step 522, and when m=z 8, l
On Saturday, step 523 performs the substitution nl←zA, and similarly m=29. z ] and O, step 525 . 527 performs the substitution 111←z B, z C.

This substitution is carried out in the enriched zone 7 with open-loop control.
−(Z
/l), 3 (2B), and 3 (ZC), the engine condition correction value Kg (z 8 ) lKT (
This is because z 9 ) and K'R(z 10 ) are used. That is, the correction value set in step 528 corresponds to the calculation of, for example, zone zA, and since m is rewritten to ZA at this point, the correction value is stored in the second storage device 4 in step 528.
To rewrite the memory at the address corresponding to zone zA (
Engine condition correction value K3' (ZA))
・It is carried out. 9. Through the above learning process, '(z A ), 3'(z
B), Ki'(zC)("old"(zB)I4K":
'(z 9 )+K'3'(z 10 )) is the current engine state correction value 1. (ZA), ..., ni3(
2C) can be rewritten.

(It)-3t3<T (in the case of restarting the supply of secondary air) During the transition period of t, ≦T<t, step 507,5 (') 8,509. 511
Release the stoppage of the secondary air along the route shown in Figure 8.

Then, in step 511, in order to prevent thermal shock in the catalyst device 16 when the supply of secondary air is resumed, the latest engine state correction value at T=t3 is added by 3(+n)(m=zA+2B Or zC) 01
Then, 3 is added to the previous engine condition correction value at T=L4.
'(+n) is set as Q2, 2*1 interpolation calculation is performed in the same way as the interpolation calculation at the time of air stop, 4 (m) is set as the engine condition correction value in the transition period, and this correction value t is calculated as follows: Set the discharge amount in .

Next, at the stage when t<T, the learning returns to normal, in other words, to the feedback zone and to the learning during secondary air supply.

Returning to FIG. 4, in the next step 6, the engine operating state determined in the previous step (specifically, the zone m
), use 1 for the temperature correction coefficient, 2 for the current air-fuel ratio correction value, and use the latest engine condition correction value currently stored at the address corresponding to the enon operation condition = ( m) is read from the second storage device 4,
The discharge amount is calculated by the following calculation.

Q= Q'x Klx K2 x The claimed discharge amount Q is converted into a pulse to be applied to the injector 8 in step 7, and the injector 8 injects fuel into the intake passage 7 in response to the pulse corresponding to the discharge iQ. Exhale.

In the above embodiment, the enriched zone ZA.

The Ennon state correction value at ZB and ZC is 3 (7
, A)+, (zB), (zC) are adjacent to each other, respectively. 8. z 9. Engine condition correction value KW (z
B ), ni'F (z 9), ni'F (z ], 0
) In short, the engine condition correction value at the time of secondary air cant is enriched with snow (to) (1n = zl ~ Z 10 ) as basic data in the feed chain. What is necessary is to calculate the engine condition correction value in the zone.For example, the engine condition correction value in the enrich zone 2A is calculated using the quadratic feedback zone z2.z5.zB that shares the engine speed r as (ZA). Ennon state correction value at air cut is blue (z2), narrow Z5).

A value obtained by appropriately manipulating the learning value of the feedback zone may be used, such as using the average value of K=(z8).

Further, in the above embodiment, the enrich zone, that is, the secondary air cut zone, and the feedback zone, that is, the secondary air supply zone are used. For example, the feedback zone, z8°, z9. zlo may be set as a secondary air cut zone. In this case, each feedback zone z8. z9. zH), the supply of secondary air is automatically stopped (cut), so there is no need to temporarily cut the secondary air. K
3(z 9 ), '=(z 10 ) can be used as is to calculate the engine condition correction values in the enrich zones z A, z B, and z C.

Further, in the above embodiment, the present invention is applied to so-called speed density fuel control in which each operating zone is specified based on the engine speed and intake negative pressure, and fuel control is performed for each operating zone. is not limited to this.

That is, the present invention provides an air meter (sensor) that detects the amount of intake air from time to time in the intake passage of the engine, and controls the operation of the engine based on the amount of intake air detected by this and the engine speed. The present invention can also be applied to a fuel control method in which a state is specified and a fuel supply amount is set in accordance with the operating state.

Further, in the above embodiment, the secondary air is supplied by the air pump 9, but instead of the air pump 9, it is possible to use a riet valve device (not shown) that closes with the positive pressure of exhaust pulsation and opens with the negative pressure. You can also do this.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of the present invention, FIG. 2 is a system configuration diagram of a fuel control system according to an embodiment of the present invention, FIG. 3 is a schematic diagram of the configuration of the computer in FIG. 2, and FIG. 4 is a fuel FIG. 5 is a flowchart showing the routine for calculating the engine condition correction value; FIG. 6 is a graph showing the engine operating range divided into a plurality of zones depending on the engine speed and intake negative pressure; FIG. 7 is a graph for explaining sampling of the air-fuel ratio correction value, and FIG. 8 is a time chart showing the timing of temporary stop and restart of secondary air at the learned value of the engine condition correction value. 1... Air-fuel ratio sensor (02 sensor) 2... Operating state sensor 3... First storage device 1... Second storage device 5... Control device 8... Injector 11... Secondary air supply passage 12...Secondary air control valve Patent applicant: Toyo Kogyo Co., Ltd. Representative: Patent attorney: Mr. Hajime and two others Fig. 1 Fig. 2 Fig. 3 Fig. 8 Fig. 4

Claims (1)

[Claims] (1) An air-fuel ratio sensor that outputs a signal corresponding to the air-fuel ratio of the air-fuel mixture taken into the engine, an operating state sensor that detects the engine operating state, and an air-fuel ratio sensor that controls the air-fuel ratio of the air-fuel mixture taken into the engine. a first storage device in which basic control values are given in advance in accordance with engine operating conditions; and a second storage device in which engine condition correction values respectively corresponding to engine operating conditions are stored in order to correct the basic control values. During closed-loop air-fuel ratio control, an air-fuel ratio correction value is calculated based on the output signal of the air-fuel ratio sensor, and the air-fuel ratio correction value is processed to obtain an engine condition correction value, which is stored in the second storage device at the time of processing. Updates the engine condition correction value corresponding to the engine operating state, calculates the air-fuel ratio correction value based on the signal from the air-fuel ratio sensor, and processes the air-fuel ratio correction value during closed-loop air-fuel ratio control and with secondary air cut. An engine condition correction value during open-loop air-fuel ratio control and when secondary air is activated is calculated based on the calculated engine condition correction value, and the engine condition correction value is stored in the open-loop air-fuel ratio control in the 152 storage device. Toki Dekatsu 2
The data is stored in correspondence with the engine operating state at the time of the next air cut, and is based on the basic control value in the first storage device, the engine condition correction value stored in the second storage device, and the output signal of the air-fuel ratio sensor. A fuel control device for an engine, comprising: a control device for controlling an air-fuel ratio of an air-fuel mixture taken into an ennon based on an air-fuel ratio correction value obtained by the air-fuel ratio correction value.