JP3336080B2 - 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 misfire when supplying fuel to a lean burn engine.

[0002]

2. Description of the Related Art So-called evaporative fuel supply aiming at both improvement of fuel efficiency and purification of exhaust gas by temporarily trapping fuel vaporized in a fuel tank, vaporizing (purging) the trapped fuel again, and supplying it to an engine. Engines equipped with the device have been put to practical use.

[0003] In the engine that supplies the evaporated fuel, the timing of supplying the purged gas is performed after confirming the warm-up state based on the engine water temperature (for example, Japanese Utility Model Publication No. 60-33316). On the other hand, for the purpose of improving fuel efficiency, a technique has been proposed in which an air-fuel ratio of an air-fuel mixture is set to a limit of lean combustion to operate an engine.

[0004]

As described above, in the lean burn engine, since the air-fuel ratio is usually set to the limit of the lean burn for λ = 1, as described above, the lean gas is used even in the lean burn engine. Even if the air is supplied after warming up, a misfire state may occur. This misfire tends to occur particularly at the start of the introduction of the purge gas in which the fluctuation of the air-fuel ratio is remarkable. This is because the air-fuel ratio feedback control has not yet been able to cope with the introduction of the purge gas at the start of the introduction of the purge gas.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned drawbacks of the prior art.
An engine control device capable of preventing occurrence of a misfire state when supplying evaporated fuel to a lean-burn engine is proposed. The configuration of the present invention for this purpose operates with a relatively lean air-fuel ratio for λ = 1.
An engine that controls the supply of evaporated fuel to a lean burn engine
Means for supplying fuel vapor in the gin control device;
Suppressing means to suppress engine misfire and supply evaporated fuel
Control means for operating the suppression means when
The control means performs the operation with the target of λ = 1 combustion and the lean operation.
Equipped with means for switching between operation and target combustion state
At the same time, the suppression means reduces the supply of the evaporated fuel to λ = 1 combustion.
Limiting misfires by restricting driving
Features. Also, relatively lean air-fuel for λ = 1
Supply of evaporated fuel to a lean-burn engine operating at
Evaporated fuel is supplied to the control device of the controlled engine
Means for suppressing engine misfire,
Control to operate the suppression means when supplying fuel
Means, and means for detecting an engine load.
The suppressing means stops the supply of the evaporated fuel during the lean burn operation.
Suppress misfire by limiting gin load to high load area
It is characterized by doing. Also, for λ = 1, relatively
Fuel in lean-burn engines operating at lean air-fuel ratios
In the engine control device that controls the feed
Means for supplying fuel and suppression of engine misfire
Means and the suppression means are operated when supplying evaporated fuel.
Control means for causing the control means to temporarily
Means for increasing the amount of fuel supplied, and the control means
Synchronized the supply of evaporative fuel and the increase
It is characterized by that.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. The present embodiment is an example in which the present invention is applied to, for example, an in-line four-cylinder engine for an automobile. First, FIG. 2 shows an overall system configuration of an evaporative fuel supply device for an engine according to the embodiment of the present invention.

First, an outline of a fuel supply control system according to an embodiment of the present invention will be described with reference to FIG. 2, and then control of main parts will be described. <Fuel Supply Control System> In FIG. 2, reference numeral 1 denotes an engine main body. Intake air is taken in from the outside via an air cleaner 30, and then supplied to each cylinder via an air flow meter 2 and a throttle chamber 3. The fuel is supplied from the fuel tank 12 to the engine side by the fuel pump 13, and is injected by the fuel injector 5. The amount of air taken into the cylinder when an accelerator pedal (not shown) is operated, such as when the vehicle is running, is controlled by a throttle valve 6 provided in the throttle chamber 3. The throttle valve 6 is operated in conjunction with the access pedal, and is maintained at the minimum opening degree in the deceleration running state and the idling operation range. In the minimum (fully closed) opening state, the idle switch ID / SW (not shown) is energized to turn on a signal indicating the idle state, and the ECU 9 detects an idle state based on this signal. be able to.

The throttle chamber 3 is provided with a bypass intake passage 7 which bypasses the throttle valve 6. The bypass intake passage 7 controls the engine speed during idling and when dashpot air is supplied. The current control type electromagnetic valve (ISC valve) 8 is provided. Therefore, in the idle operation region and the dashpot air supply state, the intake air that has passed through the air flow meter 2 is
It is supplied to each cylinder via the bypass intake passage 7, and the supply amount is adjusted by the solenoid valve 8. The open / close state of the solenoid valve 8 is controlled by a duty ratio D of a control signal supplied from an engine control unit (hereinafter abbreviated as ECU) 9.

Reference numeral 10 denotes a three-way catalytic converter (catalyst converter) 11 in the exhaust passage, for example.
1 shows an exhaust pipe having an exhaust gas purifying function provided with an exhaust pipe. The three-way catalytic converter 1 of the exhaust pipe 10
1 has an oxygen concentration in the exhaust gas (air-fuel ratio A /
An O2 sensor S1 for detecting F) is provided. The engine body 1 is provided with a knock sensor (not shown) for detecting occurrence of a knocking state.

The air-fuel ratio (A /
F) In the air-fuel ratio control system on the side of the electronic fuel injection control device in the ECU 9, the basic fuel injection amount TP is first determined based on the output value Q of the air flow meter 2 and the engine speed Ne, for example. O2 above
Using the sensor S1, the actual air-fuel ratio (A /
F) is detected, and the basic fuel injection amount TP is feedback-corrected in accordance with the deviation between the detected value and the set target air-fuel ratio, so that the set air-fuel ratio (generally, the stoichiometric air-fuel ratio A / F = 14) is always obtained. (A value near 0.7).

Accordingly, a general system for calculating the final fuel injection amount TO in the air-fuel ratio control system is as shown in FIG. 3 (described later). On the other hand, reference numeral 14 denotes an ignition plug provided in the cylinder head portion of the engine body 1, and a predetermined ignition voltage is applied to the ignition plug 14 via a distributor 17 and an igniter 18. The application timing, that is, the ignition timing is controlled by an ignition timing control signal θIgt supplied from the ECU 9 to the igniter 18. Further, reference symbol S2 is a boost pressure sensor,
An engine boost pressure B corresponding to the engine load is detected and input to the ECU 9.

The ECU 9 includes, for example, a microcomputer (CPU) as a calculation unit, a circuit for detecting an intake air amount Q, a circuit for calculating a fuel injection amount and an ignition timing, a circuit for determining an octane number of fuel, Memory (ROM
And RAM), an interface (I / O) circuit, and the like. The interface circuit of the ECU 9 includes an engine start signal (EC) from a starter switch (not shown) in addition to the detection signals described above.
U trigger), an engine speed detection signal Ne from the engine speed sensor 15, a detection signal Tw of the engine coolant temperature detected by the water temperature thermistor 16, for example, a throttle opening detection signal detected by the throttle opening sensor 4. Various detection signals necessary for engine control, such as a TVO and an intake air amount detection signal Q detected by the air flow meter 2, are input.

The ECU 9 controls the fuel injection amount according to the operating range as shown in FIG. 4, for example. On the other hand, reference numeral 31 denotes a canister provided between the downstream side of the throttle valve 6 in the intake passage of the engine and the upper portion of the fuel tank 12 for collecting fuel vapor in the fuel tank 12. The canister 31 has a charcoal filter inside its body, for example.
The fuel vapor in the fuel tank 12 is collected by being introduced into the filter unit through the fuel vapor inlet and adsorbed.

The fuel vapor in the canister 31 is purged into the intake passage of the engine through the fuel vapor supply passage 32 when the purge valve 33 is opened. The open / close state of the purge valve 33 is also controlled by the purge control signal PG from the ECU 9. As described above, the present invention is based on the premise that a means for suppressing the occurrence of a misfire is provided, and when supplying the evaporated fuel in which the misfire easily occurs, the suppression means is operated to prevent the misfire. is there. Hereinafter, four specific examples of the present invention will be described. : In the first embodiment, when the introduction of the purge gas is started,
By delaying the fuel injection timing, the air-fuel ratio around the ignition plug is made rich, and as a result, misfire is prevented. In the second embodiment, the start of the introduction of the purge gas is limited to the operation region of λ = 1, thereby preventing the occurrence of the excessive lean state of the air-fuel ratio and preventing the misfire. In the third embodiment, during the lean burn operation, the misfire is prevented by limiting the introduction of the purge gas to a load region of a predetermined value or more. In the fourth embodiment, the misfire is suppressed by temporarily increasing the fuel supply at the start of the introduction of the purge gas. <First Embodiment> FIG. 3 is a flowchart showing a control procedure according to the first embodiment.

In step S2, the cooling water temperature Tw,
The intake air amount Q and the engine speed Ne are taken in from each sensor. In step S4, it is determined based on these data whether a condition for introducing the purge gas is satisfied. The introduction conditions include that the engine water temperature is equal to or higher than a predetermined value, that the conditions for performing the air-fuel ratio feedback control are satisfied, and the like. When the introduction condition is not satisfied, the flag F indicating that the purge gas is not introduced is set to 0 in step S6. Then, in step S8, normal fuel injection timing is set.

FIG. 4 shows the injection timing of the fuel injected from the injector 5 as set in the engine of FIG. In this embodiment, the injection timing is
It is set according to the air-fuel ratio of the air-fuel mixture according to FIG. 8
The normal timing set means that a timing corresponding to the air-fuel ratio is set according to the characteristics of FIG. Step S
If it is determined that the introduction condition is satisfied in step 4,
By checking whether or not the value of the flag F is 0 in step S10, it is determined whether or not the introduction of the purge gas is to be started. If it is the start timing of the introduction of the purge gas, the flag F is set to 1 in step S12, and the timer is started in step S14. Then, in step S16, PG = 1 is set to introduce a purge gas. Then, in step S18, the fuel injection timing is set to timing B.

In FIG. 4, the injection timing A is a timing delayed from the top dead center TDC, and the timing B is further delayed. At the beginning of the purge gas introduction, by setting the timing B in step S18,
The fuel injection timing is delayed. If the injection timing is delayed, uniformity of the mixture in the combustion chamber is prevented, and a denser mixture layer is formed closer to the spark plug. Such stratification around the ignition plug makes it easier for the air-fuel mixture to ignite, and prevents misfire due to a delay in the air-fuel ratio feedback control.

Once the flag F = 1 is set in step S12, the process proceeds from step S4 to step S10 to step S20 as long as the purge gas introduction condition is satisfied. In step S20, it is checked whether the timer set in step S14 has timed out. This timer is a time that the air-fuel ratio feedback would have been able to follow the introduction of the purge gas, and is a time previously obtained by an experiment or the like. Before this time has elapsed (NO in step S20), the signal P is output in step S22.
G is maintained at 1, and the fuel injection timing is set to B in step S24. Thereby, the purge gas is introduced in a state where the introduction of the purge gas is delayed in the fuel injection timing (timing B). That is, during the period in which the air-fuel ratio feedback may not be able to follow, the injection timing is delayed, so that even if the purge gas is introduced, misfire hardly occurs.

If the timer times out, the process proceeds from step S20 to step S26, and the injection timing is set according to timing A. <Second Embodiment> In the second embodiment, the start of the introduction of the purge gas is limited to the operation region where λ = 1, thereby preventing the occurrence of the excessive lean state of the air-fuel ratio and preventing the misfire.

FIG. 5 is a flowchart showing the control procedure of the second embodiment. First, in step S30, the cooling water temperature Tw, the intake air amount Q, and the engine speed Ne are taken in from each sensor. In step S32, it is confirmed that the engine water temperature is higher than a predetermined value a, and it is checked whether the engine is warmed up. When the engine has not been warmed up, the routine returns to the main routine, and the purge gas is not introduced. When the engine is warmed up, the process proceeds to step S34, and it is determined whether or not the engine is in an operation range in which the air-fuel ratio feedback control is to be performed based on the data collected in step S30.

If it is not in the feedback operation region, the routine proceeds to step S38, at which a purge gas is introduced. On the other hand, when it is in the feedback control region, step S
When the air-fuel ratio is not λ = 1 at 36, the purge gas is not introduced. That is, in the second embodiment, even when the air-fuel ratio feedback control is performed in the warmed-up state, the introduction of the purge gas is postponed until a relatively rich mixture of λ = 1 is supplied. You. FIG. 6 conceptually shows the operation of the second embodiment. <Third Embodiment> In the third embodiment, misfire is prevented by restricting the introduction of the purge gas to a load region of a predetermined value or more during the lean burn operation. FIG. 7 shows a control procedure of the third embodiment.

Steps S40 to S44 are the same as steps S30, S32, and S34 of the second embodiment. When the engine is warmed up and the feedback control is being executed, it is checked in step S46 whether the air-fuel ratio is lean. The lean operation area is determined according to the map of FIG.
It is determined based on the engine speed Ne and the load Pe obtained at 0. The engine load Pe is a so-called pseudo load (= Q
/ Ne) or a negative pressure sensor (not shown).

When it is not in the feedback operation region or when it is not in the lean operation region, the process proceeds to step S50 to introduce the purge gas. In step S50, the purge gas is supplied with the signal PG = 1. In the feedback operation range and the lean operation range, the load state is checked in step S48. If the load Pe satisfies Pe ≧ Pa, there is no risk of misfiring, and the process proceeds to step S50 to start purging. <Fourth Embodiment> In the fourth embodiment, a misfire is suppressed by temporarily increasing the fuel supply at the start of the introduction of the purge gas. FIG. 9 shows the control procedure.

In step S60, it is determined whether the conditions for introducing the purge gas are satisfied. When the condition is not satisfied, the purge gas is not introduced. If the condition is satisfied, it is checked in step S62 whether the engine is in a lean operation state. When the engine is not in the lean operation state, there is no risk of misfire even if the purge gas is introduced. Therefore, PG = 1 is set in step S64. Step S6
If it is determined in step 2 that the engine is in the lean operation state, the process proceeds to step S66 to check whether the introduction of the purge gas has been performed for a predetermined time since the start of the introduction. If the time has not yet elapsed, the air-fuel ratio is forcibly made rich in step S68. In other words, if the condition for introducing the purge gas has not been satisfied until then and at some later time, the introduction of the purge gas is started and the air-fuel ratio is forcibly enriched for a predetermined time from that time. To This prevents misfire in the transitional period until the air-fuel ratio feedback is performed.

[0025]

Therefore, according to the engine control apparatus of the present invention, it is possible to appropriately prevent a misfire state in the case where fuel vapor is supplied.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a diagram illustrating the entire control system of the engine according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating a control procedure according to the first embodiment.

FIG. 4 is a diagram illustrating the operation of the first embodiment.

FIG. 5 is a flowchart illustrating a control procedure according to a second embodiment.

FIG. 6 is a diagram showing an operation area of the second embodiment.

FIG. 7 is a flowchart illustrating a control procedure according to a third embodiment.

FIG. 8 is a diagram showing an operation area of the third embodiment.

FIG. 9 is a flowchart illustrating a control procedure according to a fourth embodiment.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuaki Tanaka 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-5-163980 (JP, A) JP-A-Hei 4-362244 (JP, A) JP-A-4-365926 (JP, A) JP-A-2-91478 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 25/08 301 F02D 41/02 325 F02D 41/04 330 F02D 45/00 345

Claims (3)

(57) [Claims] 1. With a relatively lean air-fuel ratio for λ = 1
Controlling the supply of evaporated fuel to the operating lean-burn engine
In the engine control device, the means for supplying the evaporated fuel, the suppressing means for suppressing the engine from misfiring, and the control for operating the suppressing means when supplying the evaporated fuel are provided.
; And a control means, said control means when provided with a means for switching the operation to target operation and lean combustion condition to target lambda = 1 combustion DOO
In particular , the engine control device is characterized in that the suppression means suppresses misfire by limiting the supply of evaporative fuel to λ = 1 combustion operation. 2. With a relatively lean air-fuel ratio for λ = 1
Controlling the supply of evaporated fuel to the operating lean-burn engine
In the engine control device, the means for supplying the evaporated fuel, the suppressing means for suppressing the engine from misfiring, and the control for operating the suppressing means when supplying the evaporated fuel are provided.
And control means, and means for detecting an engine load, the suppressing means, during lean-burn operation, and characterized by inhibiting the misfire by engine load the supply of evaporative fuel is limited to the high load region Engine control device. 3. A relatively lean air-fuel ratio for λ = 1
Controlling the supply of evaporated fuel to the operating lean-burn engine
In the engine control device, the means for supplying the evaporated fuel, the suppressing means for suppressing the engine from misfiring, and the control for operating the suppressing means when supplying the evaporated fuel are provided.
Control means, wherein the suppression means includes means for temporarily increasing the amount of supplied fuel.
Mutotomoni, the control means control apparatus for an engine, wherein the synchronizing the increase of supply and the fuel supply of the fuel vapor.