JP2992382B2 - Engine fuel supply control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an engine for controlling the amount of fuel supplied to the engine so that the air-fuel ratio of the air-fuel mixture supplied to the engine for combustion matches the target air-fuel ratio.

[0002]

2. Description of the Related Art In an engine mounted on a vehicle,
When it is in an operating state or the like in which it is prioritized that exhaust gas purification is sufficiently performed, the air-fuel ratio of the air-fuel mixture supplied for combustion is made to coincide with a target air-fuel ratio set to a stoichiometric air-fuel ratio or a value near the stoichiometric air-fuel ratio. In such a state, the feedback control for the supplied fuel amount is performed, and a large output such as when the vehicle is accelerating, or an improvement in fuel efficiency should be given priority. When
The amount of fuel supplied so that the air-fuel ratio of the air-fuel mixture supplied for combustion is richer or leaner than the target air-fuel ratio under feedback control, and furthermore, the fuel supply is stopped. There is known a fuel supply control device that is provided with a fuel supply control device that is brought into a state in which open loop control is performed.

In a fuel supply control device which selectively performs such feedback control and open-loop control on the amount of supplied fuel in accordance with the operating state of the engine, the feedback control state is not taken. Oxygen concentration sensor (O
An air-fuel ratio feedback correction value is calculated based on a detection output obtained from an air-fuel ratio sensor such as a _two- sensor), and the calculated air-fuel ratio feedback correction amount is used to provide fuel injection disposed in the intake system of the engine. Correction is made for the fuel injection amount from the valve, that is, the fuel supply amount to the engine. At that time, the detection output obtained from the air-fuel ratio sensor takes a level that changes substantially linearly around the reference level according to the air-fuel ratio within a relatively narrow range around the stoichiometric air-fuel ratio. The deviated air-fuel ratio is assumed to have a substantially constant upper limit or lower limit. Therefore, under a feedback control state of the fuel supply amount, the target value of the air-fuel ratio is set to the stoichiometric air-fuel ratio. The air-fuel ratio will be within a relatively narrow range centered on the fuel ratio, and the actual air-fuel ratio obtained steadily under such conditions will fluctuate slightly around the stoichiometric air-fuel ratio or a value in the vicinity thereof. Value.

[0004] Therefore, the operating state of the engine should be such that the actual air-fuel ratio takes a value that is relatively significantly shifted from the stoichiometric air-fuel ratio to the rich side or the lean side, or the fuel supply is temporarily changed. When the state is to be stopped, the fuel supply control device switches from a feedback control state in which feedback control on the supplied fuel amount is performed to an open loop control state in which open loop control on the supplied fuel amount is performed. Made
The amount of fuel supplied is controlled so that an air-fuel ratio having a value relatively shifted to the rich side or lean side from the stoichiometric air-fuel ratio is obtained, or fuel supply to the engine is temporarily stopped.

[0005]

Under these circumstances, in the fuel supply control device, the feedback control of the amount of fuel supplied to the engine is performed in accordance with the operating state of the engine. transition to open loop control state open-loop control is performed occurs, and then, when the transition back from the open loop control state to the feedback control condition occurs, the feed bar click control state after the open loop control condition, The feedback control on the supplied fuel amount is restarted under the conditions related to the feedback control set in the feedback control state before the open loop control state. Control letter Depending on the state of the air-fuel ratio feedback correction value under the open loop control state and the fuel supply state under the open loop control state, the feedback control on the supplied fuel amount is stably performed in the feedback control state after the open loop control state. There is a possibility that an undesired delay time may be involved before the state is reached.

For example, when the vehicle is accelerated after being decelerated, the fuel supply control device performs feedback control at the start of the vehicle deceleration according to the operating state of the engine which changes accordingly. A transition from the state to the open loop control state occurs, and the open loop control state is continued during a period corresponding to the vehicle deceleration state,
When a transition from the open loop control state to the feedback control state occurs at the end of the deceleration state of the vehicle, the air-fuel ratio feedback correction value under the feedback control state before the open loop control state performs lean control, and In the case where a fuel supply stop operation is performed in which fuel supply to the engine is stopped under the open loop control state, the air-fuel ratio feedback correction value is set immediately after the start of the feedback control state after the open loop control state. Under the influence of the leaning of the air-fuel mixture due to the supply stop operation, the rich control is temporarily performed, and thereafter, the control is returned to the lean control, and therefore, the state is changed from the open loop control state to the feedback control state. After the transition, feedback control on the amount of fuel supplied By the state of stably carried out with the air-fuel ratio feedback correction value and performs the over emissions control, undesired delay occurs.

Further, in the fuel supply control device, a transition from the feedback control state to the open loop control state occurs at the start of the vehicle deceleration state, and thereafter, from the open loop control state to the feedback control state at the end of the vehicle deceleration state. When the return transition occurs, the air-fuel ratio feedback correction value under the feedback control state before the open loop control state performs rich control, and the amount of fuel supplied to the engine increases under the open loop control state. When the supplied fuel increase operation is performed, immediately after the start of the feedback control state after the open loop control state, the air-fuel ratio feedback correction value is temporarily affected by the enrichment of the air-fuel mixture due to the supplied fuel increase operation. It is assumed that lean control is performed, and then rich control is performed. Therefore, after the transition from the open loop control state to the feedback control state, the feedback control on the supplied fuel amount is stably performed with the air-fuel ratio feedback correction value that performs rich control. Until the operation is performed, an undesired delay time occurs.

In view of the above, the present invention provides a feedback control state in which feedback control is performed on the amount of fuel supplied to the engine and an open loop control state in which open loop control is performed on the amount of fuel supplied to the engine. If the transition from the feedback control state to the open loop control state occurs once, and then the transition from the open loop control state to the feedback control state occurs, the feedback before the open loop control state occurs. Regardless of the state of the air-fuel ratio feedback correction value under the control state and the fuel supply state under the open loop control state, in the feedback control state after the open loop control state, Bag The control, without undesired delay time, and an object thereof is to provide a fuel supply control device of the shall be able to make the state to be stably performed engines.

[0009]

In order to achieve the above-mentioned object, an engine fuel supply control apparatus according to the present invention is shown in FIG.
As shown in FIG. 1, an air-fuel ratio detecting means for outputting a detection output corresponding to an air-fuel ratio of an air-fuel mixture supplied to a combustion in an engine; an operating state detecting means for detecting an operating state of the engine; The air-fuel ratio of the air-fuel mixture is adjusted to a predetermined value according to the operating state of the engine detected by the detecting means.
A feedback control state in which feedback control on the amount of fuel supplied to the engine is performed based on a detection output from the air-fuel ratio detecting means so as to match the reference value, and an open loop control state in which open loop control on the amount of fuel supplied to the engine is performed. In addition to the supplied fuel amount control means that selectively takes the above, when the supplied fuel amount control means transitions from the feedback control state to the open loop control state and then to the feedback control state again, the feedback before the open loop control state After the transition from the open loop control state to the feedback control state of the supplied fuel amount control means according to the state of the air-fuel ratio feedback correction value under the control state and the fuel supply state under the open loop control state Feeding by the supplied fuel amount control means for a predetermined period Feedback to perform an operation for prohibiting updating of the air-fuel ratio feedback correction value in the click Control
Prohibition constructed and a stop means.

[0010]

In the fuel supply control device for an engine according to the present invention configured as described above, the supplied fuel amount control means temporarily shifts from the feedback control state to the open loop control state in accordance with the operation state of the engine. Then, when returning from the open loop control state to the feedback control state, the state of the air-fuel ratio feedback correction value under the feedback control state before the open loop control state and the fuel supply state under the open loop control state Specifically, for example, the air-fuel ratio feedback correction value under the feedback control state before the open loop control state is in a state in which lean control is performed, and the open loop control state If the fuel supply under the condition is in the supply stop state or before the open loop control state When the air-fuel ratio feedback correction value under the feedback control state is in a state where rich control is performed and the fuel supply under the open loop control state is in the increasing control state, The supplied fuel amount control means does not update the air-fuel ratio feedback correction value in the feedback control for a predetermined period after the shift from the open loop control state to the feedback control state.

Thus, in the feedback control state after the open-loop control state of the supplied fuel amount control means, the air-fuel ratio feedback correction value in the feedback control on the supplied fuel amount is determined by the open-loop control state of the supplied fuel amount control means. In response to the influence of the state of the fuel supply, for example, the effect of the fuel supply being stopped, or the effect of the fuel supply being in the increase control state, the opening of the supplied fuel amount control means It is possible to avoid a situation in which a predetermined time is required until a state similar to the air-fuel ratio feedback correction value in the feedback control under the feedback control state before the loop control state is achieved. In the feedback control state after the open loop control state by the control means Feedback control for the supply fuel amount is a state of stable carried out without undesirable delay.

[0012]

FIG. 2 shows an example of a fuel supply control device for an engine according to the present invention, together with a main part of the engine to which the fuel supply control device is applied.

In FIG. 2, an intake passage 9 and a cylinder 6 provided with an engine body 1 and having a piston 4 forming a combustion chamber 2 at an upper portion thereof are communicated through an intake valve 7 and an exhaust valve 8. An exhaust passage 10 is connected. In the intake passage 9, an air cleaner 11, an air flow meter 12 for detecting an intake flow rate, a throttle valve 13 for opening and closing the intake passage 9, and a surge tank 1 are arranged in this order from the upstream side.
5 and a fuel injection valve 17 for injecting fuel pumped from the fuel supply system toward the intake port are provided. Air-fuel mixture formed by intake air from the intake passage 9 and fuel injected from the fuel injection valve 17 is supplied to the combustion chamber 2, and the air-fuel mixture is subjected to combustion to generate exhaust gas. Is discharged to the exhaust passage 10. In the exhaust passage 10,
An O ₂ sensor 18 for detecting the oxygen concentration in the exhaust gas is provided, and a catalytic converter 19 is provided at a portion downstream of the O ₂ sensor 18. Each of the air flow meter 12 and the O ₂ sensor 18 is connected to the control unit 30.

The control unit 30 includes a detection output signal Sa obtained from the air flow meter 12, a detection output signal So obtained from the O ₂ sensor 18, and the throttle valve 13.
The detection output signal St obtained from the throttle opening sensor 14 for detecting the opening (throttle opening) of the engine, the detection output signal Sn obtained from the rotation speed sensor 20 for detecting the engine rotation speed, and cooling of the engine body 1 A detection output signal Sw obtained from a water temperature sensor 21 for detecting a water temperature, a shift position sensor 2 for detecting a position of a shift lever for switching a shift speed of a transmission attached to the engine body 1.
2 and a detection output signal Sk obtained from the clutch operation sensor 23 that detects a state in which the clutch pedal is depressed. Based on these various detection output signals, the control unit 30 adjusts the target air-fuel ratio to, for example, the stoichiometric air-fuel ratio so that the air-fuel ratio matches the target air-fuel ratio. Feedback control, deceleration fuel supply stop control for stopping fuel supply to the engine body 1 when the vehicle on which the engine body 1 is mounted is decelerated, and the engine body 1
Open-loop control for the amount of fuel supplied to the engine body 1 such as deceleration supply fuel increase control for increasing the amount of fuel supplied to the engine body 1 when the vehicle on which the vehicle is mounted is decelerated is selectively performed. .

In the feedback control of the amount of fuel supplied to the engine body 1 by the control unit 30, the operating state of the engine body 1 indicated by the detected output signals Sa and Sn is indicated by the intake flow rate and the engine speed, respectively. When the detected output signals Sa and Sn are detected as belonging to the operating region of the engine in which the feedback control is to be performed, the basic fuel injection amount Qb is determined based on the intake flow rate and the engine speed represented by the detected output signals Sa and Sn, respectively.
Is calculated, and an air-fuel ratio feedback correction value Cf, which is assumed to have a change corresponding to the detection output signal So obtained from the O ₂ sensor 18, is set. Injection amount Q
b, and the corrected fuel injection amount Qm [= Qb ·
Cf] is obtained, and the corrected fuel injection amount Qm
Is added to the final fuel injection amount Qv.
f [= Qm + Qv] is set. Then, an injection drive pulse signal PA having a pulse width corresponding to the set final fuel injection amount Qf is formed, and supplied to the fuel injection valve 17 at a timing synchronized with the rotation of the engine. As a result, the fuel injection valve 17 is opened only for a period corresponding to the pulse width of the injection drive pulse signal PA, and the fuel is injected from the fuel injection valve 17 into the cylinder 6 with an injection amount corresponding to the pulse width of the injection drive pulse signal PA. It is controlled so that the air-fuel ratio of the air-fuel mixture which is injected and supplied to the downstream of the intake passage 9 communicating with the combustion chamber 2 formed at the upper part of the combustion chamber 2 and used for combustion in the combustion chamber 2 matches the target air-fuel ratio. Will be.

On the other hand, when the control unit 30 performs the fuel supply stop control at the time of deceleration of the engine body 1, the operation of the engine body 1 is performed based on the throttle opening and the engine speed represented by the detection output signals St and Sn, respectively. Under the condition that the throttle valve 13 is substantially fully closed, it is detected that the engine speed is equal to or higher than a predetermined value, and the detected output signals Sp and Sk indicate the position of the shift lever and the operating state of the clutch pedal, respectively. On the basis of this, a gear other than “neutral” is selected from among the gears of the transmission attached to the engine body 1 and that the clutch pedal is not depressed and the engine body 1 It is detected that the power transmission path leading to the vehicle is in a connected state, and it is detected that the vehicle is in a decelerating traveling state. Luo, the detection output signal Sa of the time
, And Sn indicate that the operating state of the engine body 1 indicated by the intake flow rate and the engine speed, respectively, belongs to the operating region of the engine in which the preset fuel supply stop control at the time of deceleration is to be performed. Then, the above-described feedback control is stopped, the supply of the injection drive pulse signal PA from the control unit 30 to the fuel injection valve 17 is stopped, and the fuel injection supply from the fuel injection valve 17 is stopped. Then, thereafter, the detection output signals Sa and Sn
Is detected that the operating state of the engine main body 1 indicated by the intake flow rate and the engine rotation speed respectively no longer belongs to the operating region of the engine in which the fuel supply stop control at the time of deceleration is to be performed, or the detection output signal St It is detected that the deceleration traveling state of the vehicle has ended based on the throttle opening and the engine speed represented by Sn and Sn, respectively, and the shift lever position and the operation state of the clutch pedal represented by the detection output signals Sp and Sk, respectively. Then, the supply of the injection drive pulse signal PA from the control unit 30 to the fuel injection valve 17 is restarted, and the fuel injection valve 17 is returned to the state of performing the fuel injection supply.

When the control unit 30 performs the deceleration supply fuel increase control on the supply fuel amount to the engine body 1 at the time of deceleration, the detection output signals St and S
n represents the throttle opening and the engine speed,
And, based on the position of the shift lever and the operation state of the clutch pedal represented by the detection output signals Sp and Sk, respectively, it is detected that the vehicle is in the deceleration driving state, and the detection output signals Sa and Sn at that time are respectively detected. When it is detected that the operating state of the engine main body 1 indicated by the intake air flow rate and the engine speed belongs to an operating region of the engine in which the control of increasing the supplied fuel during deceleration is to be performed, a detection output signal is output. The basic fuel injection amount Qb is calculated based on the intake flow rate and the engine speed represented by Sa and Sn. Further, an open-loop correction value Cn based on the cooling water temperature or the like represented by the detection output signal Sw and an increase correction value Ci based on the engine speed or the like represented by the detection output signal Sn are set, and the open-loop correction value Cn is added to the basic fuel injection amount Qb. And the fuel injection amount Qm [= Qb · Cn · Ci] corrected by multiplying the fuel injection amount Qm and the increase correction value Ci.
Is required. Then, the invalid fuel injection amount Qv is added to the corrected fuel injection amount Qm, and the final fuel injection amount Qf
[= Qm + Qv] is set, and an injection drive pulse signal PA having a pulse width corresponding to the set final fuel injection amount Qf is formed and supplied to the fuel injection valve 17 at a timing synchronized with the rotation of the engine. Is done. As a result, the fuel injection valve 17 is opened only for a period corresponding to the pulse width of the injection drive pulse signal PA, and the fuel injection valve 1 is opened.
From 7, the fuel whose amount has been increased is injected and supplied to the downstream portion of the intake passage 9 leading to the combustion chamber 2 formed above the cylinder 6 with an injection amount corresponding to the pulse width of the injection drive pulse signal PA.

Thereafter, the detection output signals Sa and S
When it is detected that the operating state of the engine main body 1 indicated by the intake flow rate and the engine speed represented by n respectively does not belong to the operating region of the engine in which the supply fuel increase control at the time of deceleration is performed, or a detection output signal St
It is detected that the deceleration traveling state of the vehicle has ended based on the throttle opening and the engine speed represented by Sn and Sn, respectively, and the shift lever position and the operation state of the clutch pedal represented by the detection output signals Sp and Sk, respectively. Then, the fuel injection amount Q corrected from the basic fuel injection amount Qb
In order to obtain m, the increase correction value Ci is set to “1”, that is, the state where the increase correction to the basic fuel injection amount Qb is not performed (Qm = Qb · Cn). Fuel that is not to be increased
A state in which an injection amount corresponding to the pulse width of the injection drive pulse signal PA is injected and supplied to the downstream portion of the intake passage 9 that communicates with the combustion chamber 2 formed in the upper portion of the cylinder 6, or the amount of fuel supplied as described above. Is performed.

Under such circumstances, the vehicle is decelerated under the feedback control state in which the control unit 30 performs the feedback control using the air-fuel ratio feedback correction value Cf for the amount of fuel supplied to the engine body 1. The driving state is set, whereby the feedback control state is ended, and instead,
An open loop control state in which deceleration fuel supply stop control for the engine body 1 or deceleration supply fuel increase control for the amount of fuel supplied to the engine body 1 is performed, and thereafter, after the vehicle ends the deceleration running state , When the feedback control state is established again, the air-fuel ratio feedback correction value Cf under the feedback control state before the open loop control state performs lean control, and the engine is controlled in the open loop control state thereafter. When the fuel supply stop control at the time of deceleration for the main body 1 is performed, or the air-fuel ratio feedback correction value Cf under the feedback control state before the open loop control state performs rich control, and Engine in open loop control state When the deceleration supply fuel increase control for the supply fuel amount to the main body 1 is performed, the feedback control for the supply fuel amount to the engine main body 1 is performed for a predetermined period at the beginning of the feedback control state after the open loop control state. The update of the air-fuel ratio feedback correction value Cf is prohibited.

That is, when a transition from the open loop control state to the feedback control state occurs, the air-fuel ratio feedback correction value Cf under the feedback control state before the open loop control state performs lean control, Further, when the deceleration fuel supply stop control for the engine body 1 is performed in the open loop control state thereafter, or when the air-fuel ratio feedback correction value Cf under the feedback control state before the open loop control state performs rich control. To do,
Further, when the deceleration supply fuel increase control for the supply fuel amount to the engine main body 1 is performed in the subsequent open loop control state, in the predetermined period at the beginning of the feedback control state shifted from the open loop control state. The feedback control of the amount of fuel supplied to the engine body 1 is performed without changing the air-fuel ratio feedback correction value Cf set to a predetermined value, for example, “1” under the open loop control state. It is supposed to be used.

For example, as shown in FIGS. 3A and 3B,
An open-loop control state (O) in which the feedback control state (F / B) is taken until time point ta, the vehicle is decelerated from time point ta to time point tb, and the vehicle speed Vc is reduced.
PEN), and thereafter, when the feedback control state is resumed after the time point tb, as shown in FIG. 3C, the air-fuel ratio feedback correction value Cf under the feedback control state up to the time point ta becomes lean. Control is performed, and from time ta to time tb
The air-fuel ratio feedback correction value Cf is set to “1” during the period of the open loop control state until
When the deceleration fuel supply stop control for the engine body 1 is performed, as shown by a solid line in FIG.
A predetermined period TA from time tb to time tc under a feedback control state after time tb.
, The air-fuel ratio feedback correction value Cf is “1”.
, The feedback control on the amount of fuel supplied to the engine body 1 is performed. And
After time tc after a predetermined period TA from time tb to time tc has elapsed, the air-fuel ratio feedback correction value Cf is controlled by feedback control until time ta in accordance with the detection output signal So from the O ₂ sensor 18. The lean control is performed in the same manner as the air-fuel ratio feedback correction value Cf under the state, and is updated.

In this case, as shown by a dashed line in FIG. 3C, the air-fuel ratio feedback correction value Cf is detected from the O ₂ sensor 18 from the beginning under the feedback control state after the time point tb. Assuming that feedback control is performed on the amount of fuel supplied to the engine body 1 by being updated in response to the output signal So, during the period from time ta to time tb, the deceleration fuel for the engine body 1 is used. The air-fuel ratio feedback correction value Cf obtained immediately after the time point tb is subjected to the rich control under the influence of the leaned air-fuel mixture because the supply stop control is performed and the air-fuel mixture is lean. Will be obtained as And
The air-fuel ratio feedback correction value Cf obtained as a result of performing the rich control immediately after the time point tb is such that the lean control is gradually performed according to the detection output signal So from the O ₂ sensor 18. Therefore, in such a case,
Under the feedback control state after the time point tb, the air-fuel ratio feedback correction value Cf is stable under the condition that the lean control is performed similarly to the air-fuel ratio feedback correction value Cf under the feedback control state up to the time point ta. It will take a relatively long time to be implemented.

Actually, as shown by the solid line in FIG. 3C, under the feedback control state after the time point tb, the air-fuel ratio feedback correction value Cf is changed to a predetermined value from the time point tb to the time point tc. In the period TA, it is maintained at “1”, and is updated in accordance with the detection output signal So from the O ₂ sensor 18 after time tc after the period TA has elapsed.
Due to the fuel supply performed at A, the effect of the air-fuel mixture leaned by the deceleration fuel supply stop control on the engine body 1 during the period from the time point ta to the time point tb is affected by the air-fuel ratio feedback correction value Cf after the time point tc. It is assumed that it does not reach. Therefore, after time tc after the elapse of the period TA, the air-fuel ratio feedback correction value Cf, which is to be updated in accordance with the detection output signal So from the O ₂ sensor 18, is relatively short after time tb. In the meantime, the lean control is performed in the same manner as the air-fuel ratio feedback correction value Cf under the feedback control state up to the time point ta.

As shown in FIGS. 4A and 4B, the feedback control state is maintained until time ta ',
An open-loop control state in which the vehicle is decelerated and the vehicle speed Vc is reduced from a ′ to time tb ′,
Thereafter, when the feedback control state is taken again after the time point tb ′, as shown in FIG. 4C, the air-fuel ratio feedback correction value Cf under the feedback control state up to the time point ta ′ performs rich control. Further, during the period of the open loop control state from the time point ta ′ to the time point tb ′, the air-fuel ratio feedback correction value Cf is set to “1”, and the deceleration supply fuel increase control for the engine body 1 is performed. If
As shown by the solid line in FIG.
A predetermined period TA ′ from time tb ′ to time tc ′ under the following feedback control state
, The air-fuel ratio feedback correction value Cf is “1”.
, The feedback control on the amount of fuel supplied to the engine body 1 is performed. And
After time tc ′ after a predetermined period TA ′ from time tb ′ to time tc ′ has elapsed, the air-fuel ratio feedback correction value Cf is changed to the time ta at time ta in accordance with the detection output signal So from the O ₂ sensor 18. It is assumed that rich control is performed in the same manner as the air-fuel ratio feedback correction value Cf under the feedback control state up to ′, and is updated.

In this case, as shown by the dashed line in FIG. 4C, the air-fuel ratio feedback correction value Cf is supplied from the O ₂ sensor 18 from the beginning under the feedback control state after the time point tb ′. Assuming that the feedback control is performed on the amount of fuel supplied to the engine main body 1 by being updated in accordance with the detection output signal So, the time point t 'to the time point tb'
In the period until, the fuel supply increase control during deceleration for the engine body 1 is performed and the air-fuel mixture is enriched, so the air-fuel ratio feedback correction value Cf obtained immediately after the time point tb ′ is enriched. Under the influence of the air-fuel mixture, lean control is performed.
The air-fuel ratio feedback correction value Cf obtained as a result of performing the lean control immediately after the time point tb ′ is:
The rich control is gradually performed according to the detection output signal So from the O ₂ sensor 18. Therefore, in such a case, under the feedback control state after the time point tb ′, the air-fuel ratio feedback correction value Cf becomes the air-fuel ratio feedback correction value under the feedback control state until the time point ta ′. It takes a relatively long time until the control is performed to perform rich control similarly to Cf.

In practice, as shown by the solid line in FIG. 4C, the air-fuel ratio feedback correction value Cf is changed from the time tb 'to the time tc' under the feedback control state after the time tb '. Is maintained at "1" during the predetermined period TA ', and the predetermined period TA'
At time tc 'later after but a lapse, O ₂ sensor 1
8 is updated in response to the detected output signal So from the engine 8 in the predetermined period TA ′, the fuel supply during deceleration to the engine body 1 during the period from the time point ta ′ to the time point tb ′. It is assumed that the influence of the air-fuel mixture leaned by the stop control does not affect the air-fuel ratio feedback correction value Cf after the time point tc ′. Therefore, the time t after the elapse of the period TA '
After c ′, the detection output signal S from the O ₂ sensor 18
The air-fuel ratio feedback correction value Cf, which is updated in accordance with the value o, is set within a relatively short time after the time point tb ', under the feedback control state up to the time point ta'. In the same manner as described above, the control is stabilized by performing the rich control.

The control unit 30 for performing the operation control as described above is constituted by using, for example, a microcomputer. An example of a program executed by the microcomputer in such a case is shown in the flowchart of FIG. It will be described with reference to FIG.

In the program shown in FIG. 5, after the start, various detection output signals are fetched in step 41, and it is determined in step 42 whether a feedback control condition (F / B condition) is satisfied. Such a determination is made by the engine body 1 indicated by the intake flow rate and the engine speed represented by the detection output signals Sa and Sn, respectively.
Is determined by determining whether or not the operating state of the engine belongs to an operating area of the engine in which the preset feedback control is to be performed. As a result, when the F / B condition is satisfied, it is determined in step 43 whether or not the F / B condition is newly satisfied based on the determination result in the past step 43. If the result of determination in step 43 is that the F / B condition has not been newly established, in step 44, the timer flag F
It is determined whether or not t is “1”, and the timer flag F
If t is not "1", the process proceeds to step S48.

In step 48, the air-fuel ratio feedback correction value Cf is calculated based on the detected output signal So which changes according to the oxygen concentration in the exhaust gas. In the next step 49, the detected output signals Sa and Sn are respectively calculated. The basic fuel injection amount Qb is calculated based on the intake flow rate and the engine speed, and the routine proceeds to step 50. In step 50, the basic fuel injection amount Qb is multiplied by the air-fuel ratio feedback correction value Cf, and the corrected fuel injection amount Qm [=
Qb · Cf], and in step 51,
The final fuel injection amount Qf [= Qm + Qv] is calculated by adding the invalid fuel injection amount Qv to the corrected fuel injection amount Qm. In the subsequent step 52, a pulse corresponding to the final fuel injection amount Qf calculated in step 51 is calculated. An injection drive pulse signal PA having a width is formed and sent to the fuel injection valve 17 at a timing synchronized with the rotation of the engine, and the process returns to step 41.

If the result of determination in step 43 is that the F / B condition is newly established, it is determined in step 53 whether the state flag Fc or the state flag Fg is "1". If the state flag Fc or the state flag Fg is "1", the state flag Fc and the state flag Fg are determined in step 54.
The one that is “1” is set to “0”, and the routine proceeds to step 55.

In step 55, the built-in timer starts the measuring operation.
The timer flag Ft is set to "1". Then, in step 57, the air-fuel ratio feedback correction value Cf
Is determined to be a predetermined value Cfr, and if the air-fuel ratio feedback correction value Cf is not set to the predetermined value Cfr, in step 58, the air-fuel ratio feedback correction value Cf is set to the predetermined value Cfr. Then, the routine proceeds to step 49, where the air-fuel ratio feedback correction value C
When f is set to the predetermined value Cfr, the process directly proceeds to step 49, and the steps after step 49 are performed as described above.

If the result of the determination in step 53 is that the state flag Fc and the state flag Fg are not both "1", in step 59, the detection output signal So that changes in accordance with the oxygen concentration in the exhaust gas. After calculating the air-fuel ratio feedback correction value Cf based on
The process proceeds to step 9 and the steps after step 49 are performed as described above.

Further, if the result of the determination in step 44 is that the timer flag Ft is "1", in step 45, it is determined whether or not the measured time Tt of the timer has exceeded the period TA, and Time Tt is period T
If it exceeds A, proceed to step 46;
If the measured time Tt of the timer does not exceed the period TA, the process proceeds to step 57, and the steps after step 57 are performed as described above. In step 46, the measuring operation of the timer is stopped, and in step 4
At step 7, after setting the timer flag Ft to "0", the process proceeds to step 48, and the steps after step 48 are performed as described above.

On the other hand, as a result of the judgment in step 42, F /
If the condition B is not satisfied, it is determined in a step 60 whether or not the deceleration fuel supply stop control condition is satisfied. Such a determination is based on the detection output signals St and Sn
, Based on the throttle opening and the engine speed, respectively, and the detection output signals Sp and Sk, based on the position of the shift lever and the operating state of the clutch pedal, respectively.
It is determined whether or not the vehicle is in a decelerating running state. Further, the operating state of the engine main body 1 indicated by the intake flow rate and the engine speed represented by the detection output signals Sa and Sn is set to a predetermined fuel supply during deceleration. This is performed by determining whether or not the engine belongs to the operation area of the engine where the stop control is to be performed. As a result, when the fuel supply stop control condition at the time of deceleration is not satisfied, it is determined at step 61 whether or not the fuel supply increase control condition at the time of deceleration is satisfied. Such a determination is based on the detection output signals St and Sn
, Based on the throttle opening and the engine speed, respectively, and the detection output signals Sp and Sk, based on the position of the shift lever and the operating state of the clutch pedal, respectively.
It is determined whether or not the vehicle is in a decelerating running state. Further, the operating state of the engine body 1 indicated by the intake flow rate and the engine speed represented by the detection output signals Sa and Sn is a predetermined deceleration supply fuel. This is performed by determining whether or not it belongs to the operating region of the engine in which the increase control is to be performed. As a result, when the deceleration supply fuel increase control condition is satisfied, the routine proceeds to step 62.

In step 62, the status flag F
It is determined whether or not g is "1". If the status flag Fg is not "1", in step 63, the status flag Fg is set to "1", and the process proceeds to step 64. If Fg is “1”, the process proceeds directly to step 64. In step 64, it is determined whether the air-fuel ratio feedback correction value Cf is set to a predetermined value Cfr, and the air-fuel ratio feedback correction value Cf is determined.
If is not set to the predetermined value Cfr, in step 65, the air-fuel ratio feedback correction value Cf is set to the predetermined value Cfr, and then the process proceeds to step 66, and the air-fuel ratio feedback correction value Cf is set to the predetermined value Cfr. If so, the process proceeds directly to step 66.

In step 66, the detection output signal S
The open loop correction value Cn is calculated based on the cooling water temperature or the like represented by w, and the increase correction value Ci is calculated based on the engine speed or the like represented by the detection output signal Sn. Further, in step 67, the detection output signal Sa
And Sn to calculate the basic fuel injection amount Qb based on the intake flow rate and the engine speed, respectively.
In step 8, the basic fuel injection amount Qb calculated in step 67 is multiplied by the open loop correction value Cn and the increase correction value Ci calculated in step 66, and the corrected fuel injection amount Qm [= Qb · Cn · Ci] is obtained. And then step 5
The process proceeds to step 1 and the steps after step 51 are performed as described above.

If the result of the determination in step 61 is that the deceleration supply fuel increase control condition is not satisfied, in step 69, the open loop correction value Cn is determined based on the cooling water temperature and the like represented by the detection output signal Sw. Is calculated,
In the following step 70, the increase correction value Ci is set to "1", and then the process proceeds to step 68, and the steps after step 68 are performed as described above.

Further, if the result of the determination in step 60 is that the fuel supply stop control condition for deceleration is satisfied, it is determined in step 71 whether the state flag Fc is set to "1". , The state flag Fc is “1”
If not set in step 72,
After the state flag Fc is set to "1", the process proceeds to step 73. If the state flag Fc is set to "1", the process directly proceeds to step 73. Step 73
Is determined whether the air-fuel ratio feedback correction value Cf is set to the predetermined value Cfr. If the air-fuel ratio feedback correction value Cf is not set to the predetermined value Cfr, then at step 74, the air-fuel ratio feedback correction Step 75 after setting the correction value Cf to the predetermined value Cfr
If the air-fuel ratio feedback correction value Cf is set to the predetermined value Cfr, the process directly proceeds to step 7
Go to 5. Then, in step 75, the process returns to step 41 in a state where the transmission of the ejection drive pulse signal PA is stopped.

[0039]

As is clear from the above description, in the fuel supply control device for an engine according to the present invention, the supply fuel amount control means temporarily changes from the feedback control state to the open loop state according to the operation state of the engine. When transitioning to the control state and then returning from the open loop control state to the feedback control state, when the air-fuel ratio feedback correction value under the feedback control state before the open loop control state and the open loop control state In accordance with the fuel supply state, the air-fuel ratio feedback correction value in the feedback control is not updated for a predetermined period after the transition from the open loop control state to the feedback control state. Supply in the feedback control state after the open loop control state of the means The air-fuel ratio feedback correction value in the feedback control on the fuel amount is affected by the state of the fuel supply under the open loop control state of the supplied fuel amount control means, for example, the effect of the fuel supply being stopped. Alternatively, under the influence of the fuel supply being in the increase control state, the same as the air-fuel ratio feedback correction value in the feedback control under the feedback control state before the open loop control state of the supply fuel amount control means. It is possible to avoid a situation where a predetermined time is required until the state is set, and as a result, the feedback control of the supplied fuel amount by the supplied fuel amount control means in the feedback control state after the open loop control state is not performed. The operation is performed stably without a desired delay time.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing an engine fuel supply control device according to the present invention, corresponding to the claims.

FIG. 2 is a schematic configuration diagram showing an example of an engine fuel supply control device according to the present invention together with a main part of an engine to which the fuel supply control device is applied.

FIG. 3 is a characteristic diagram used to explain an operation in the example shown in FIG. 2;

FIG. 4 is a characteristic diagram used to explain an operation in the example shown in FIG. 2;

FIG. 5 is a flowchart illustrating an example of a program executed by the microcomputer when the control unit in the example illustrated in FIG. 2 is configured by the microcomputer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine main body 6 Cylinder 9 Intake passage 12 Air flow meter 13 Throttle valve 14 Throttle opening sensor 17 Fuel injection valve 18 O ₂ sensor 20 Speed sensor 21 Water temperature sensor 22 Shift position sensor 23 Clutch operation sensor 30 Control unit

Continuation of front page (56) References JP-A-64-36943 (JP, A) JP-A-64-36942 (JP, A) JP-A-3-70836 (JP, A) JP-A-63-219844 (JP, A) , A) Real opening 61-43953 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 41/14 310

Claims (3)

(57) [Claims] 1. An air-fuel ratio detecting means for outputting a detection output according to an air-fuel ratio of an air-fuel mixture provided for combustion in an engine; an operating state detecting means for detecting an operating state of the engine; In accordance with the operating state of the engine detected by the above, feedback control on the amount of fuel supplied to the engine is performed based on the detection output from the air-fuel ratio detecting means so that the air-fuel ratio of the air-fuel mixture matches a predetermined target value. A fuel supply amount control means for selectively taking a feedback control state to be performed and an open loop control state to perform an open loop control on the fuel supply amount to the engine; and When the state shifts to the feedback control state again after the Depending on the state of the air-fuel ratio feedback correction value under the feedback control state before the state and the fuel supply state under the open loop control state, the state of the open loop control state of the supplied fuel amount control means is changed. migration after a predetermined period to the feedback control state, anda feedback prohibition <br/> stopping means for performing an operation for prohibiting updating of the air-fuel ratio feedback correction value in accordance with the feedback control the fuel supply amount control means A fuel supply control device for the engine to be configured. 2. A feedback prohibition means, when the fuel supply amount control means changes from the feedback control state again feedback control state after shifting to the open loop control condition, the open loop control state prior to the feedback control The air-fuel ratio feedback correction value under the state is in a state where the lean control is performed, and
When the fuel supply under the open loop control state is in the supply stop state, the supply fuel amount control is performed for a predetermined period after the supply fuel amount control means shifts from the open loop control state to the feedback control state. 2. The fuel supply control device for an engine according to claim 1, wherein an operation of prohibiting updating of the air-fuel ratio feedback correction value in the feedback control by the means is performed. 3. A feedback prohibition means, when the fuel supply amount control means changes from the feedback control state again feedback control state after shifting to the open loop control condition, the open loop control state prior to the feedback control The air-fuel ratio feedback correction value under the state is in a state where rich control is performed, and
When the fuel supply under the open loop control state is in the increase control state, the supply fuel amount control is performed for a predetermined period after the supply fuel amount control means shifts from the open loop control state to the feedback control state. 2. The fuel supply control device for an engine according to claim 1, wherein an operation of prohibiting updating of the air-fuel ratio feedback correction value in the feedback control by the means is performed.