JP3076884B2 - Engine 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 control device for an engine, and more particularly, to the prevention of thermal deterioration of a catalyst provided in an exhaust passage for purifying exhaust gas.

[0002]

In the control of an engine, the air-fuel ratio conventionally, for example as described in JP 61-252352 discloses a load of the engine to normal operating conditions at the time of warm-up, based on the number of revolutions Set the feedback area,
In this region, the air-fuel ratio feedback control is performed by controlling the fuel injection amount, etc., and the fuel increase region is set on the high load side to secure the output by increasing the fuel and to cool the exhaust system catalyst by the unburned gasoline. There is a known fuel increase. Separately, when the engine speed becomes high, for example, 7000 rpm, the fuel is stopped to prevent overspeed, or when the vehicle speed exceeds, for example, 180 km / h, the fuel is stopped. Conventionally, a fuel cut region is set so as to prevent overspeed.

[0003]

However, the engine control device is configured to set the fuel increase region on the high load side as described above and to secure the output and cool the catalyst by correcting the fuel increase. In the conventional technology, when the fuel is stopped to prevent overspeed and overspeed, the catalyst temperature rises rapidly at the time of transition from the fuel cut region to the fuel increase region, and the catalyst heats up. Deterioration cannot be avoided. That is, when the fuel increase region and the fuel cut region are set, the fuel is stopped in the fuel cut region, the output decreases, the rotation decreases, and when the fuel enters the fuel increase region, the catalyst disposed in the exhaust passage is set. A large amount of air is adsorbed when the fuel is stopped, and a large amount of fuel suddenly enters, causing a sudden reaction, and especially in a high-power engine with a large fuel increase value, the catalyst temperature rises sharply. The catalyst is thermally degraded.

[0004] The present invention was made in view of the above problems, and an object thereof is to prevent thermal degradation of the exhaust system catalyst during the transition to fuel increase state from a fuel cut state of the engine.

[0005]

FIG. 1 is an overall configuration diagram of the present invention for achieving the above object. That is, the engine control device according to the present invention includes an operating state detecting unit that detects a parameter related to an operating state of the engine, a fuel control unit that controls a basic fuel supply amount according to an output of the operating state detecting unit, An operating area determining means for receiving an output of the operating state detecting means and determining an operating area of the engine, and an output of the operating area determining means for determining whether the operating state of the engine is engine.
When the engine is in the fuel increasing region at high load and the output of the operating region determining device receives the output of the fuel increasing device for performing the fuel amount increasing correction for controlling the basic fuel supply amount by the fuel controlling device and the operating region determining device, the operation state of the engine is changed. a control device for an engine that includes a fuel cut means for stopping the fuel supply Ri by the fuel control means when in the predetermined fuel cut region, when the operating condition of the engine changes from the fuel cut region to the fuel increase region Is detected, and the fuel increase means is provided for a predetermined period from the transition.
, An increase limiting means for limiting the increase correction by means of the above is provided.

[0006] Here, the fuel cut means may be an over-speed fuel cut means operative during overspeed fuel cut means or vehicle overspeed operates when the engine overspeed.

[0007]

When the operating state of the engine is detected and it is determined that the fuel is in a predetermined fuel increase region for a high load increase or the like, a fuel increase correction is performed and the fuel supplied to the engine is increased. Also, the operating state of the engine is
When it is determined that the predetermined fuel cut region is for preventing the vehicle from overspeeding, the supply of fuel to the engine is stopped. When the operating state of the engine shifts from the fuel cut state to the fuel increase state, the fuel increase correction is limited for a predetermined period from the shift. As a result, a sudden reaction caused by a large amount of fuel flowing suddenly to the catalyst that has absorbed a large amount of air with the fuel cut is suppressed, and thermal deterioration of the catalyst is prevented.

[0008]

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

FIG . 2 is an overall system diagram of the first embodiment of the present invention. In this embodiment, an air flow sensor 3 for detecting an intake air amount and a throttle valve 4 for adjusting the intake air amount are arranged in the intake passage 2 of the engine 1 in order from the upstream side.
And an injector 5 for fuel injection, and a bypass passage 6 for bypassing the throttle valve 4 is formed. The bypass passage 6 is provided with an ISC valve 7 for controlling idle speed, which is constituted by a solenoid valve. Are arranged. A catalyst device 9 for purifying exhaust gas is provided in the exhaust passage 8 of the engine 1, and an air-fuel ratio of the engine is determined upstream of the catalyst device 9 based on an oxygen concentration in the exhaust gas for air-fuel ratio feedback control. Is provided with an O ₂ sensor 10 for detecting the pressure. An ignition plug 12 is provided in a combustion chamber 11 of the engine. The ignition plug 12 is connected to an igniter 14 via a distributor 13.

[0010] air-fuel ratio of the engine 1, ignition timing, control such as idle speed is performed by the control unit 15 constituted by a microcomputer. for that reason,
The control unit 15 receives an intake air amount signal from the air flow sensor 3, an engine rotation signal from a rotation sensor attached to the distributor 13 as information, and an engine water temperature signal from a water temperature sensor 16 attached to the engine 1. Further, an air-fuel ratio signal is input from the O ₂ sensor 10. The control unit 15 determines the fuel injection amount, ignition timing, ISC
Calculation of the control amount and the like is performed, and the injector 5, the igniter 1
4. Output a control signal to the ISC valve 7 and the like.

In this embodiment, the ignition timing and IS
The control of C is not different from the conventional control. In the fuel injection control, in a warm-up state in which the engine water temperature is equal to or higher than a predetermined value, the air-fuel ratio feedback control by controlling the fuel injection amount is performed in a predetermined region (air-fuel ratio feedback control region) defined by the engine load and the rotation speed. In the high-load / high-speed region (high-load increasing region) that exceeds the air-fuel ratio feedback region, the air-fuel ratio feedback control is stopped and the high-load fuel is increased. Further, in this embodiment, an overspeed fuel cut region is set to prevent the engine speed from exceeding a predetermined value (for example, 7000 rpm) and becoming an overspeed state. A fuel control system is configured. The air-fuel ratio feedback control region, the high load increase region, and the overspeed fuel cut region are defined by a region diagram shown by the engine load and the rotation speed shown in FIG. Further, in this embodiment, an overspeed fuel cut region is separately set so that fuel cut is performed even when the vehicle speed becomes equal to or higher than a fixed speed (for example, 180 km / h). Also, when the fuel cut is performed after entering the overspeed fuel cut area or entering the overspeed fuel cut area, the engine speed decreases and shifts to the high load increase area, or the vehicle speed decreases and the fuel increase also occurs. However, if the load is increased suddenly at this time, a large amount of fuel flows into the catalytic device 9 in a state where a large amount of air is adsorbed, and a rapid reaction occurs, which causes thermal degradation of the catalyst. Therefore, in order to prevent this, when shifting from the fuel cut region to the high load increasing region, for example, as indicated by an arrow B in FIG.
The fuel is not increased for a predetermined period. When the air-fuel ratio feedback control region shifts to the high load increase region as indicated by the arrow A in FIG. 3, the fuel increase is executed immediately as usual.

FIG . 4 is a flowchart for executing the control of the fuel injection of this embodiment, and S101 to S117 show each step. Start by this flow,
First, in S101, an intake air amount signal, an engine rotation signal,
Various signals such as a water temperature signal and an air-fuel ratio signal are read. Then, the process proceeds to S102, in which the vehicle speed is set to a constant speed α (α = 18
0 km / h) is determined, and if not (YES), the flow proceeds to S103.

In S103, it is determined whether or not the operating state of the engine is in a warm-up state and is in an air-fuel ratio feedback control region (F / B zone) set by the load and the rotation speed shown in FIG. In the feedback control region, the feedback correction amount CFB for performing the normal air-fuel ratio feedback control based on the air-fuel ratio signal in S104.
Then, in S105, a basic injection amount (pulse width) Tp is calculated based on the intake air amount and the engine speed. Then, various correction amounts C such as water temperature correction are calculated in S106, and a final injection amount (pulse width) Ti is calculated by adding C and CFB to Tp in S107, and a pulse width corresponding to the final injection amount Ti is calculated. An injection pulse is output to the injector 5 to execute injection.

On the other hand, if it is determined in step S103 that the engine is not in the air-fuel ratio feedback control area (NO), the process proceeds to step S109 to determine whether the operating state of the engine is in the predetermined high load increasing area (high load zone) shown in FIG. It is determined whether or not it is in the high load increasing area (YES),
Proceeding to 110, the previous time is the overspeed fuel cut area or the overspeed fuel cut area, and the fuel cut (F /
See if C) was being performed. If the previous time is the fuel cut state (YES), it is determined that the current fuel cut area has shifted to the high load increase area, the timer value T is set in S111, and the flow proceeds to S112 to perform the high load increase correction amount Cer. Is set to 0 (zero),
Proceed to S105. Then, the basic injection amount Tp is calculated in S105, the various correction amounts C are calculated in S106, and the process goes to S107 to add C and Cer (= 0) to Tp, that is, to stop the air-fuel ratio feedback control. In addition, the final injection amount Ti in a state where the high load increase correction is also stopped is calculated and output to the injector in S108.

If it is determined in S110 that the last time is not the fuel cut state (NO), the flow goes to S113 to see if the timer value T is not 0 (zero), and T = 0.
If not (YES), the timer value T is decremented (decremented) in S114, and the routine proceeds to S112, in which the suspension of the high load increase correction is continued. Then, the determination in S113 is NO
That is, if T = 0, the flow goes to S115 to clip the timer value T to 0 (zero), and then goes to S116 to set the high load increase correction amount Cer to a predetermined value, and goes to S105.
From step S106 to step S107, and set Tp to C and Ce.
r, the final injection amount Ti is calculated, and S10
Output at 8.

If the determination in S103 is NO (not in the air-fuel ratio feedback control area) and the determination in S109 is NO (not in the high load increase area), the fuel cut-off area is set. Ti is 0 (zero)
And

In this embodiment, the case where the high load increase correction amount is set to zero for a predetermined period when shifting from the fuel cut region to the high load increase region has been described. Even if it is not set to zero, it is also possible to appropriately limit the high load correction as long as the catalyst protection can be achieved.

As means for preventing thermal deterioration of the catalyst when shifting from the fuel cut area to the high load increase area, other means include:
It is also possible to use advance correction of the ignition timing. That is, in the second embodiment of the present invention, when shifting from the overspeed fuel cut region and the overspeed fuel cut region to the high load increase region, the regular high load increase is performed as usual, and the ignition timing is set for a predetermined period. correcting the predetermined amount advance, thereby to suppress an increase in unburned component flowing into the catalyst device earn combustion period.

In the second embodiment, the overall system diagram is the same as that of FIG. 2, and the control of the fuel injection is performed based on the same region diagram as that of FIG. And
When shifting from the fuel cut area to the high load increase area,
Advance correction of the ignition timing is performed by the flow chart shown in FIG.

In the flowchart shown in FIG .
01 to S212 indicate each step. Starting with this flow, first, in S201, an intake air amount signal,
Reads various signals such as the engine rotation signal. Then, the process proceeds to S202, and the basic ignition timing IgB is set from a map of the engine load and the rotation speed.

Next, in S203, determines whether a predetermined high-load increase amount region operating state of the engine makes a fuel increase (high-load zone), it means that a high-load increase amount region (YES) For example, the process proceeds to S204, and it is determined whether or not the fuel cut (F / C) was performed in the previous time in the overspeed fuel cut region or the overspeed fuel cut region. Then, if the previous time is the fuel cut state (YES), it is determined that the current fuel cut area has shifted to the high load increasing area, and a timer value T is set in S205, and the processing proceeds to S206, where a predetermined advance correction amount is set. I
gA is set, and the routine proceeds to S207, where the final ignition timing Ig is set by adding IgA to IgB, and is output to the igniter in S208.

If it is determined in S204 that the last time is not the fuel cut state (NO), the flow goes to S209 to check whether the timer value T is not 0 (zero), and if it is not T = 0 (YES). Subtracts the timer value T in S210, proceeds to S206, and continues the advance angle correction. And S
If the determination in 209 is NO, that is, if T = 0, S211
To clip the timer value T to 0 (zero), then to S212 to set the advance correction amount IgA to 0 (zero), set the final ignition timing in S207, and set S208.
To output.

The above embodiments relate to the protection of the catalyst at the time of shifting from the overspeed fuel cut region and the overspeed fuel cut region to the high load increase region. It may be applied only to control when shifting to the high load increase area from either the fuel cut area or the overspeed fuel cut area, and the fuel increase area covers acceleration increase other than high load increase. It is also possible to extend the control to the above. Further, as the catalyst protection means, it is also possible to use both the limitation of fuel increase such as high load increase and the advance correction of the ignition timing, and it is also possible to use other means such as secondary air control of the exhaust system. It is.

[0024]

Since the present invention is configured as described above, when the operation state of the engine shifts from the fuel cut state to the fuel increase state, the exhaust system in which a large amount of air is adsorbed in the fuel cut state. It is possible to prevent the catalyst from being thermally degraded due to a large amount of air flowing through the catalyst.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is an overall system diagram of a first embodiment of the present invention.

FIG. 3 is a control area diagram according to the first embodiment of the present invention.

FIG. 4 is a flowchart for executing control according to the first embodiment of the present invention;

FIG. 5 is a flowchart for executing control according to a second embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 engine 3 air flow sensor 5 injector 8 exhaust passage 9 catalyst device 12 spark plug 13 distributor 14 igniter 15 control unit

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F02P 5/15 F02P 5/15 B (56) References JP-A-63-280832 (JP, A) JP-A-59-155549 ( JP, A) JP-A-59-28029 (JP, A) JP-A-54-55237 (JP, A) JP-A-52-72026 (JP, A) JP-A-63-255537 (JP, A) JP-A-1-167442 (JP, A) JP-A-62-168944 (JP, A) JP-A-2-50039 (JP, U) JP-A-61-126024 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) F02D 41/04 330 F02D 41/10 330 F02D 41/14 310 F02D 41/22 330

Claims (3)

(57) [Claims] An operating state detecting means for detecting a parameter relating to an operating state of the engine; a fuel controlling means for controlling a basic fuel supply amount according to an output of the operating state detecting means; receiving the output, and determines the operation region determining means for operating region of the engine, receives the output of the operating range determining means, operating state of the engine en
When the engine is in the fuel increasing area at high load, the fuel increasing means for increasing the amount of fuel for controlling the basic fuel supply amount by the fuel controlling means for catalyst cooling , and receiving the output of the operating area determining means, and operating condition is an engine control system and a fuel cut means for stopping by Ri fuel supplied to said fuel control means when in the predetermined fuel cut region, the operating state of the engine from the fuel cut region Detecting a time when the fuel increasing region has been shifted to, and restricting the fuel increasing correction by the fuel increasing means for a predetermined period from the time of the shift .
Engine control apparatus is characterized by providing a bulking limiting means that. 2. An engine control apparatus according to claim 1 , wherein said fuel cut means is an overspeed fuel stop means which operates when the engine is overspeeding. Wherein said fuel cut means, the control device for an engine of Ah <br/> Ru claim 1, wherein the over-speed fuel stop means operative when the vehicle overspeed.