JP2002357151A - Control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an engine which can hold a good condition of combustion. SOLUTION: In the case that an engine speed is increased to a target value after the engine speed is lowered down, the timing of fuel supply to an intake port of an engine is set to before intake action, in the case that the engine speed is again lowered down by a prescribed value or more according to this intake asynchronous injection, the timing of fuel supply is switched during the intake action, and in the case that the engine speed is not lowered down by the prescribed value or more, a good condition of combustion can be maintained by not switching the timing of fuel supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an engine control device.

[0002]

2. Description of the Related Art A conventional engine control device is disclosed in Japanese Patent Laid-Open No.
No. 22997. In the engine control device described in the publication, the intake air amount during idle operation is feedback-controlled, and the engine speed is maintained at a target speed.

[0003]

However, when the fuel is different, that is, when heavy fuel is used,
Depending on the intake air amount feedback, the engine speed cannot reach the target speed.

That is, when heavy fuel is used, a large amount of fuel adheres to the intake port when the engine is cold started,
The fuel vaporization ratio decreases, and the combustion state deteriorates. When the combustion state is deteriorated, if feedback control for increasing the intake air amount is performed, the negative pressure in the intake pipe is reduced, so that the fuel vaporization amount is further reduced, and the combustion state is further deteriorated. Therefore, when such control is performed, the engine speed does not reach the target speed.

[0005] The present invention has been made in view of such problems, and an object of the present invention is to provide an engine control device capable of maintaining a good combustion state.

[0006]

In order to solve the above-mentioned problems, an engine control apparatus according to the present invention provides an "intake asynchronous injection" for terminating fuel injection before an intake period of the engine and a fuel injection control device in the intake period of the engine. The present invention is directed to a control device that controls an injector so that “suction synchronous injection” that terminates injection is performed in an intake port.

This control device performs intake-synchronous injection when the engine speed decreases, and then performs intake-asynchronous injection when the engine speed increases to a target value. When the number decreases again by the predetermined value or more, the injection is switched to the intake synchronous injection, and when the number does not decrease by the predetermined value or more, the injector is controlled to continue the intake asynchronous injection.

[0008] When heavy fuel is used, the amount of fuel attached during asynchronous intake injection is large, and the combustion state is likely to deteriorate.
At the time of engine start, intake synchronous injection is more preferable. On the other hand, if the fuel is not a heavy fuel, the amount of fuel adhesion is relatively small, so that asynchronous intake air injection in which air and fuel are sufficiently mixed is preferable. In addition, even if it is the same fuel, it is also possible to handle each as a separate fuel depending on the temperature difference between the regions where the engine is applied.

In order to determine the difference between these fuels, the control device of the present invention (1) performs intake-synchronous injection when the engine speed decreases, and attempts to improve the combustion state.
(2) Thereafter, when the engine speed has increased to the target value as a result of the trial, asynchronous intake injection is performed to promote the mixing of air and fuel, thereby attempting to further improve the combustion state. However, this step serves not only to improve the combustion state but also to determine the fuel characteristics. That is, as a cause of the decrease in the engine speed in the above (1), the case where the idle speed control (ISC) is separately functioning or the case where the amount of friction of the piston increases may be considered. Number drop phenomenon,
If a phenomenon in which the engine speed decreases is observed also in step (2), it can be assumed that the cause is that the fuel is heavy.

Therefore, in the step (3), when the engine speed drops again by a predetermined value or more due to the asynchronous intake injection in the step (2), the fuel having a large amount of adhesion, that is, the heavy fuel Therefore, it is switched to the intake synchronous injection. If the engine speed does not decrease by the predetermined value or more, the fuel can be treated as not being heavy fuel, and therefore, the asynchronous intake injection in step (2) is continued.

The duration of the continuation is several seconds or more. After a lapse of several seconds or more, the warm-up of the intake port of the engine is almost completed, so that another control may be started.

When the water temperature is equal to or lower than a predetermined value, the fuel is likely to adhere. Therefore, it is preferable that the control of the injector be performed when the water temperature at the time of starting the engine is equal to or lower than the predetermined value.

Further, if the engine speed is controlled by adjusting the ignition timing after detecting deterioration of the combustion of the engine, the engine speed can be controlled irrespective of the characteristics of the fuel. The rotation speed can be made closer to the target value.

In particular, if there is a history of the switching after detecting the deterioration of the combustion of the engine, it can be estimated that the fuel is heavy fuel. Therefore, if the engine speed is controlled by adjusting the ignition timing, it is possible to use heavy fuel. Since the engine speed can be controlled even if the engine speed is higher, the engine speed can be closer to the target value than the control based on the supply air amount.

In addition, after detecting the deterioration of engine combustion, if there is no history of the switching, it can be estimated that the fuel is not heavy fuel. Therefore, the advance amount of the current ignition timing is determined, and based on the determination result, Then, the subsequent control method may be determined.

At this time, since it is estimated that the fuel is not a heavy fuel, if the advance amount of the ignition timing is less than a predetermined value, it is not necessary to perform the control based on the ignition timing. However, the engine speed can be controlled by adjusting the amount of air supplied to the intake port, and the load on the engine can be reduced.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An engine control device according to an embodiment will be described below.

FIG. 1 is a block diagram of an engine system including an engine control device according to the embodiment.

The engine E is provided with an intake port PA for guiding air and fuel to the combustion chamber and an exhaust port PE for discharging exhaust gas generated in accordance with the combustion in the combustion chamber. The engine rotates at a rotational speed sensor R as the engine rotational speed.
Is detected by

An intake pipe TB is connected to the intake port PA, and a throttle valve V is interposed in the intake pipe TB. An injector I is attached to the intake port PA. Injector I has a fuel tank FT
Is supplied with fuel through a fuel pump FP. The opening degree of the throttle valve V and the timing of fuel injection from the injector I are controlled by control signals Si and Sv from the electronic control unit ECU. Note that a bypass passage may be provided in the intake pipe TB, and a flow rate of the bypass passage may be controlled in addition to the throttle valve V as a method of controlling the amount of air supplied to the intake port.

An exhaust pipe TB 'through which exhaust gas passes is attached to the exhaust port PE, and an oxygen sensor OX is arranged in the exhaust pipe TB'. The engine temperature is
The water temperature is detected by a water temperature sensor W attached to a water jacket of the engine E.

Output signals from the rotational speed sensor R, the water temperature sensor W, and the oxygen sensor OX are input to the electronic control unit ECU, and the electronic control unit ECU opens the throttle valve V based on these input signals. It functions as an engine control device that controls the degree and the timing of fuel injection from the injector I. The details are described below.

FIG. 2 is a timing chart for explaining control according to the embodiment. Electronic control unit EC
The injector U is controlled so that the “intake asynchronous injection” for terminating the fuel injection before the intake period of the engine E and the “synchronous intake injection” for terminating the fuel injection within the intake period of the engine E are performed in the intake port PA. Control. In other words, before the negative pressure is generated in the intake port PA, the injection method for terminating the fuel injection is defined as intake asynchronous injection, and the injection method in which the fuel injection is not completed until the negative pressure is generated is defined as the intake synchronous injection. Stipulate.

The electronic control unit ECU performs intake-synchronous injection when the engine speed input from the speed sensor R decreases, and thereafter performs intake-asynchronous injection when the engine speed increases to a target value. If the engine speed drops again by a predetermined value or more due to the asynchronous intake injection, the system switches to intake synchronous injection, and if not, the injector I is controlled to continue the intake asynchronous injection.

FIG. 3 is a graph showing the time dependence of the engine speed when heavy fuel is used. In addition,
In the graph, the fuel injection method performed at each time is described, in which a high level indicates intake asynchronous injection and a low level indicates intake synchronous injection.

When heavy fuel is used, if the water temperature (the temperature of the intake port) is low, the amount of fuel deposited during the asynchronous injection of the intake is large, and the combustion state is likely to be deteriorated. Is preferred. On the other hand, if the fuel is not a heavy fuel (it is assumed to be a light fuel) and the water temperature (the temperature of the intake port) is high, the amount of deposited fuel is relatively small.
Intake asynchronous injection, in which the air and fuel are well mixed, is preferred. In addition, even if it is the same fuel, it is also possible to handle each as a separate fuel depending on the temperature difference between the regions where the engine is applied.

The electronic control unit ECU performs intake synchronous injection immediately after turning on the ignition switch, and thereafter performs intake asynchronous injection when the (actual) engine speed exceeds the target engine speed. In the description, the actual engine speed is simply referred to as the engine speed.

After switching to the asynchronous intake injection, (1) when the engine speed decreases (by a given value or more than the target engine speed), intake synchronous injection is performed again (time T1) and its combustion Try to improve the condition.

(2) Thereafter, when the engine speed increases to the target value as a result of the improvement trial, intake asynchronous injection is performed (T2) to promote the mixing of air and fuel, thereby further improving the combustion state. Try to improve. However, this step serves not only to improve the combustion state but also to determine the fuel characteristics. That is, as a cause of the decrease in the engine speed in the above (1), the idle speed control (I
SC) may function separately, or the amount of friction of the internal components of the engine such as the piston may increase. However, the second engine speed reduction phenomenon at the time T2, that is, also in the process (2), If a phenomenon in which the engine speed decreases is observed, it can be assumed that the cause is that the fuel is heavy.

Therefore, in the step (3), if the engine speed drops again by a predetermined value or more due to the asynchronous intake injection in the step (2), the fuel having a large amount of adhesion, that is, the heavy fuel Therefore, the mode is switched to the intake synchronous injection (time T3).

FIG. 4 is a graph showing the time dependence of the engine speed when using light fuel. In the graph, the fuel injection method performed at each time is described. The high level indicates intake asynchronous injection, and the low level indicates intake synchronous injection. The control up to immediately before step (3) is the same as the method described with reference to FIG. 3, but here, in step (3), the engine speed does not decrease by a predetermined value or more. In this case, since the fuel can be handled as not being a heavy fuel, the asynchronous intake air injection in the step (2) performed after the time T2 is continued.

The duration of the continuation is several seconds or more. When the time of several seconds or more has elapsed, the warm-up of the intake port of the engine is completed, and the above-described sensors R, W, and OX are used.
Air-fuel ratio (A / F) feedback (F
B) Another control such as control may be started. This embodiment does not prevent the asynchronous intake injection from being performed in the air-fuel ratio feedback control.

FIG. 5 is a flowchart for executing the above control. By turning on the ignition switch, the engine E is started, and the idling fuel injection timing control routine is started.

First, it is determined whether or not combustion deterioration is detected, for example, when the engine speed falls below the target engine speed (S1). Until combustion deterioration is detected, intake asynchronous injection is performed (S10).

When the deterioration of the combustion is detected, it is determined whether or not the air-fuel ratio feedback control has been started (S2). If the conditions for starting the air-fuel ratio feedback control are satisfied, the air-fuel ratio feedback control is started. .
In this example, the air-fuel ratio feedback control is performed by intake asynchronous injection (S10).

If the conditions for starting the air-fuel ratio feedback control are not satisfied, it is determined whether the flag E is OFF (S3). If the flag E is OFF, the engine speed is restored to the target engine speed. It is determined whether or not it has been performed (S4). That is, the deviation of the current engine speed from the target engine speed is ΔR,
If the threshold value is NE1 (for example, NE1 = −20 rpm), and ΔR is larger than NE1, for example, ΔR = −1
In the case of 0 rpm, it is determined that the engine speed has recovered to the target engine speed.

If the engine speed has recovered, it is determined that the ignition timing advance margin is greater than or equal to a predetermined value (S
5) If the advance angle has a margin, the intake asynchronous injection is performed, the flag E is turned ON (S6), and if there is no margin, the intake synchronous injection is performed.

That is, the ignition timing is set to a predetermined value (for example, crank angle: 5) with respect to the advance side guard value (near MBT).
If there is a margin, the operation returns to the asynchronous intake injection, but if it is less than the predetermined value, the return to the asynchronous intake injection is not performed. This is because, in the case of heavy fuel, the transition from intake synchronous injection to intake asynchronous injection causes a decrease in the rotational speed.However, if there is enough advance in the advance angle guard value, the ignition timing must be advanced. In addition, it is possible to suppress a decrease in the engine rotation speed, and when there is no margin, when the fuel injection method is switched to the intake asynchronous injection by setting the fuel injection method to the intake synchronous injection without advancing the ignition timing. This is because it is possible to suppress a sense of discomfort due to the change in the number of rotations. Further, when such a guard value is used, the threshold value NE2 of the decrease width of the engine speed can be set small.

Since the flag E is turned on in step S6, in the next flow, it is determined that the flag E is not off in step S3. Further, by changing to asynchronous intake air injection in step S6, the engine speed is reduced. Is determined whether or not (S
7). That is, assuming that the deviation of the current engine speed from the target engine speed is ΔR and the second threshold value is NE2 (for example, NE2 = −100 rpm), when ΔR is smaller than NE1, for example, when ΔR = −150 rpm,
It is determined that the engine speed has dropped below the target engine speed by a predetermined value or more.

When the engine speed decreases (S7),
The intake asynchronous injection is switched to the intake synchronous injection, and the flag X is turned ON (S8).

When the engine speed does not decrease (S
7) It is determined whether or not the flag X is ON (S9). If it is not ON, that is, if the engine speed does not decrease due to the intake asynchronous injection, it is estimated that this is light fuel, and the intake asynchronous The injection is continued (S10). If the flag X has been turned ON even once, that is, if the engine speed has decreased due to the asynchronous intake injection, the flag X is determined (S9).
In, it is determined that this is heavy fuel, and intake synchronous injection is performed (S8).

When the water temperature is equal to or lower than a predetermined value, fuel is likely to adhere. Therefore, it is preferable that the above-described control is performed when the water temperature at the time of starting the engine is equal to or lower than the predetermined value.

FIG. 6 is a graph showing the time dependency of the amount of hydrocarbon (HC) discharged from the engine per unit time. FIG. 3 also shows the speed of the vehicle on which the engine is mounted. Is a graph when the intake asynchronous control is performed from the start of the engine to the time when the air-fuel ratio feedback control is performed, the graph when the control according to the above-described embodiment is performed, and the air-fuel ratio feedback control after the determination of combustion deterioration. It is a graph at the time of performing intake synchronous control until it performs. The graph shows that the amount of HC is smaller than when the control is used.

FIG. 7 is a flow chart for performing feedback control of the engine speed during idling of the engine.

When the ignition switch is turned on, the engine E is started, and an idling engine speed feedback control routine is started.

First, it is determined whether or not combustion deterioration is detected, for example, when the engine speed falls below the target engine speed (S21). Until combustion deterioration is detected, the engine speed is maintained at the idling engine speed by controlling the amount of air supplied to the intake port, and the speed feedback control is performed (S28).
When the deterioration of combustion is detected, it is determined whether the air-fuel ratio feedback control has not been started (S22). If the conditions for starting the air-fuel ratio feedback control are satisfied, the air-fuel ratio feedback control is started. In this example, the air-fuel ratio feedback control performs feedback control of the engine speed by adjusting the air amount (S2).
8).

If the conditions for starting the air-fuel ratio feedback control are not satisfied, it is determined whether or not the flag E is OFF (S23).
If the asynchronous intake air injection is not set after the recovery of the engine speed, the engine speed is feedback-controlled by controlling the ignition timing (S24).

On the other hand, if the flag E is ON, that is, if the asynchronous intake air injection is set after the engine speed is recovered, as in step S7 in FIG.
Further, it is determined whether or not the engine speed has decreased (S25). If the engine speed has decreased, the ignition timing is controlled to perform feedback control of the engine speed (S2).
4). If the engine speed does not decrease, it is determined whether or not the advance amount of the ignition timing is smaller than a predetermined value (for example, 3 degrees of crank angle) (S26). It is attenuated to zero, and is switched to feedback control of the engine speed by controlling the air amount (S
27).

If the advance amount of the ignition timing is equal to or more than the predetermined value, the feedback control of the engine speed by adjusting the ignition timing is continued because the feedback control by adjusting the air amount is impossible (S24). ).

With the above control, the engine speed feedback control based on the ignition timing can be terminated early, so that the advance amount is attenuated to zero, and a decrease in catalyst warm-up can be suppressed.

In this control, after detecting deterioration of engine combustion, the engine speed is controlled by adjusting the ignition timing. Therefore, the engine speed can be controlled irrespective of the characteristics of the fuel, and the engine speed can be controlled by the supply air amount. The engine speed can be closer to the target value than the control.

The control of this embodiment can be used in combination with the above control. That is, in the control of the present example, if there is a history of switching the injection method after detecting the deterioration of the combustion of the engine (S8, S25), it can be estimated that the fuel is heavy fuel. The engine speed can be controlled even if the fuel is heavy, and the engine speed can be made closer to the target value than the control based on the supply air amount.

In the control according to the present embodiment, it is possible to estimate that the fuel is not heavy if there is no history of the switching after detecting the deterioration of the engine combustion. (S26), and the subsequent control method is determined based on the determination result. At this time, since it is estimated that the fuel is not heavy fuel, when the advance amount of the ignition timing is less than a predetermined value, it is not necessary to perform control based on the ignition timing. Therefore, since the engine speed is controlled by reducing the advance angle and adjusting the amount of air supplied to the intake port, the load on the engine can be reduced (S27).

Next, control for suppressing hunting immediately after the start of the engine will be described. This control can also be combined with the control described above. The engine speed is detected, and if hunting is likely to occur, the feedback gain in the engine speed feedback control may be reduced, or the engine speed region (dead zone) where feedback control is not performed may be expanded. The details are described below.

FIG. 8 is a flowchart for performing feedback control of the engine speed when the engine is idling. By turning on the ignition switch,
The engine speed feedback control routine when the engine E is idling starts. First, a water temperature at the time of engine start (engine temperature: intake port temperature) is detected, and it is determined whether the water temperature is equal to or lower than a predetermined value (the engine is in a cold state or a semi-warm state) (S31). If the water temperature is higher than the predetermined value, the feedback gain of the ISC or the dead zone is set to a normal value, and the amount of air supplied to the intake port is controlled so that the engine speed during idling becomes substantially constant (S36).

If the water temperature is equal to or lower than the predetermined value, it is detected whether or not the engine speed after the start is lower than the predetermined value (S32). Until the water temperature drops, the control in step S36 is performed. Then, it is detected whether or not the engine speed has increased or decreased by a predetermined value or more from the target engine speed, that is, whether or not the engine speed has overshot (S33).

If the engine speed does not overshoot, the control in step S36 is performed. If it does, it is determined whether the conditions for starting the air-fuel ratio feedback control are satisfied (S34). Is satisfied, the air-fuel ratio feedback control is started, the control in step 36 is performed.

When it is determined whether the start condition of the air-fuel ratio feedback control is satisfied (S34), if the air-fuel ratio feedback control is not started because the condition is not satisfied, the feedback gain of the ISC is increased. The feedback control of the engine speed during idling is suppressed or prohibited by reducing the above-mentioned normal value or expanding the above-mentioned dead zone beyond the above-mentioned normal value (S3).
5). Here, instead of the feedback control, a feedback control for keeping the engine speed at idling constant by controlling the ignition timing may be performed.

FIG. 9 is a graph showing the time dependency of the engine speed when the feedback gain is reduced. If the engine speed drops below the rotation speed detection threshold immediately after the engine is started, it is determined that the engine speed has dropped, and then the deviation of the engine speed from the target engine speed is detected as the lower limit or upper limit overshoot. If the threshold value is exceeded, it is determined that the engine speed has hunted and the feedback controllability has been degraded.
The feedback gain in the engine speed feedback control by C (control for adjusting the amount of air supplied to the intake port so that the engine speed becomes the idle speed) is reduced, and hunting of the engine speed is suppressed. The dotted line shows the engine speed when such a gain reduction is not performed.

The time dependence of the rotational speed feedback air amount (correction amount) by ISC is also shown in FIG. As the feedback gain decreases, the amount of time change of the air amount decreases. Note that the dotted line indicates the amount of air when gain reduction is not performed.

In this control, a dead zone in which feedback control of the engine speed is not performed is set within a predetermined range from the target engine speed.

FIG. 10 is a graph showing the time dependency of the engine speed when the dead zone is expanded. If the engine speed drops below the rotation speed detection threshold immediately after the engine is started, it is determined that the engine speed has dropped, and then the deviation of the engine speed from the target engine speed is detected as the lower limit or upper limit overshoot. If the threshold value is exceeded, it is determined that the engine speed has hunted and the feedback controllability has deteriorated, and a dead zone in which the engine speed feedback control by the ISC is not applied is expanded to suppress the engine speed hunting.
The dotted line indicates the engine speed when such a dead zone is not expanded.

FIG. 9 also shows the time dependency of the rotational speed feedback air amount (correction amount) based on the ISC. As the dead zone expands, the amount of time change of the air amount decreases. The dotted line indicates the air amount when the dead zone is not expanded.

In the above-described control, the hunting suppression control such as the reduction of the feedback gain is started with the detection of the deterioration of the feedback control property as a trigger. Alternatively, hunting suppression control may be performed.

FIG. 11 is a flowchart for performing feedback control of the engine speed during idling based on such a method. Turn on ignition switch
As a result, the engine speed feedback control routine when the engine E is idling starts. First, the water temperature at the start of the engine is detected, and it is determined whether the water temperature is equal to or lower than a predetermined value (S41). If the water temperature is higher than the predetermined value, the feedback gain of the ISC is set to a normal value, and the amount of air supplied to the intake port is controlled so that the engine speed during idling becomes substantially constant (S4).
7).

If the water temperature is equal to or lower than the predetermined value, it is detected whether or not the engine speed after starting has become lower than the predetermined value (S42). Until the engine speed decreases, the control in step S47 is performed. Then, it is determined whether a predetermined time has elapsed after the engine is started (S43).

If the predetermined time has not elapsed after the start of the engine, the above-described hunting suppression control such as reducing the feedback gain of the ISC is performed (S44). If a predetermined time has elapsed after the engine is started, it is determined whether the start condition of the air-fuel ratio feedback control is satisfied (S45). If the condition is satisfied, the air-fuel ratio feedback control is started. Then, it is determined whether or not the increase width of the water temperature from the start is less than a predetermined value, and if it is more than the predetermined value, the control in step S47 is performed, and if it is less than the predetermined value, the control in step S44 is performed. In addition, as a result of determining whether or not the start condition of the air-fuel ratio feedback control is satisfied, the control of step S44 is also performed when the air-fuel ratio feedback control is not started because the condition is not satisfied.

The above steps S43, S44, S4
5 as independent determination conditions in step S42.
After the determination condition, the process may proceed to step S44 or S47.

As described above, in the present embodiment, after the temperature of the intake port rises, the amount of fuel adhering to the port decreases, and after the responsiveness of the rotational speed to the change in the ISC air amount is restored, By setting the feedback gain as usual, hunting can be suppressed.

As described above, according to the engine control apparatus described with reference to FIGS. 1 to 6, when the engine speed increases to the target value after the engine speed decreases, the fuel supply timing to the intake port of the engine is reduced by the intake air. The fuel supply timing is set before the operation, and when the engine speed again decreases by a predetermined value or more due to the asynchronous intake injection, the fuel supply timing is switched during the intake operation. In addition, a good combustion state can be maintained according to the type of fuel.

According to the engine control device described in the above, the engine speed feedback control based on the ignition timing can be terminated early.

According to the engine control device described in FIG. 8 and subsequent figures, hunting can be suppressed by detecting overshoot of the engine speed.

[0073]

According to the engine control device of the present invention, a good combustion state can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an engine system including an engine control device according to an embodiment.

FIG. 2 is a timing chart for explaining control according to the embodiment.

FIG. 3 is a graph showing the time dependence of the engine speed when heavy fuel is used.

FIG. 4 is a graph showing the time dependence of the engine speed when light fuel is used.

FIG. 5 is a flowchart by the control device.

FIG. 6 is a graph showing the time dependency of the amount of hydrocarbon (HC) discharged from the engine per unit time.

FIG. 7 is a flowchart for performing feedback control of the engine speed during idling of the engine.

FIG. 8 is a flowchart for performing feedback control of the engine speed during idling of the engine.

FIG. 9 is a graph showing the time dependence of the engine speed when the feedback gain is reduced.

FIG. 10 is a graph showing the time dependency of the engine speed when the dead zone is expanded.

FIG. 11 is a flowchart for performing feedback control of the engine speed during idling.

[Explanation of symbols]

E: engine, ECU: electronic control unit, FP: fuel pump, FT: fuel tank, I: injector, OX ...
Oxygen sensor, PA: intake port, PE: exhaust port, R
... Rotation speed sensor, TB ... Intake pipe, TB '... Exhaust pipe, V ...
Throttle valve, W ... water temperature sensor.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F02D 43/00 F02D 43/00 301K F02P 5/15 F02P 5/15 Z F-term (reference) 3G022 AA01 CA02 DA00 3G084 AA05 BA03 BA04 BA15 BA17 CA02 DA08 EB16 EC03 FA20 FA33 3G301 HA24 JA07 KA05 LA01 LB01 MA19 MA21 NE01 PE01A PE08Z

Claims (7)

[Claims] 1. A control device for controlling an injector so that asynchronous intake injection that terminates fuel injection before an intake period of an engine and synchronous intake injection that terminates fuel injection within an intake period of the engine are performed in an intake port. In the above, when the engine speed decreases, the intake synchronous injection is performed. Thereafter, when the engine speed increases to a target value, the asynchronous intake injection is performed. The engine control device switches to the intake synchronous injection when the value decreases by more than a predetermined value, and controls the injector to continue the intake asynchronous injection when the value does not decrease by a predetermined value or more. 2. The engine control device according to claim 1, wherein the continuation period is several seconds or more. 3. The engine control device according to claim 1, wherein the control of the injector is performed when a water temperature at the time of starting the engine is equal to or lower than a predetermined value. 4. The engine control device according to claim 1, wherein after detecting deterioration of combustion of the engine, the engine speed is controlled by adjusting ignition timing. 5. The engine control according to claim 1, wherein after detecting the deterioration of the combustion of the engine, if there is a history of the switching, the engine speed is controlled by adjusting the ignition timing. apparatus. 6. The method according to claim 1, wherein after detecting the deterioration of the combustion of the engine, if there is no history of the switching, an advance amount of the ignition timing is determined, and a subsequent control method is determined based on the determination result. The engine control device according to claim 1, wherein 7. When the advance amount of the ignition timing is less than a predetermined value, the advance amount is reduced, and the engine speed is controlled by adjusting the amount of air supplied to the intake port. The engine control device according to claim 6, wherein: