JPH11343914A - Starting controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the improvement of startability and the reduction in HC exhaust quantity. SOLUTION: Fuel injection is performed in an intake process at the starting time, thereby reducing the attachment of the fuel to an intake port or the like. Furthermore, if the engine speed rise value DNE is larger than the fuel judgement value α at the starting time, the engine speed rise upper limit value βis determined (steps 304, 306), and if the engine speed rise value DNE is larger than the engine speed rise upper limit value β, it is judged not to ensure the intake open valve time required to cause the fuel quantity necessary for the starting to flow in the combustion chamber, so that by determining the ignition delay angle collection value FAOP in accordance with the guard-over value γ(=DNE-β) of the engine speed rise, the starting time ignition timing AST is delayed for angle correction (steps 307-310). This permits the engine speed rise at the starting time to be controlled to the engine speed rise upper limit value β or less, and the intake open valve time necessary at the starting time can be ensured, thereby permitting the fuel quantity necessary for the continuous combustion to surely flow in the combustion chamber at the low-temperature starting time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start control device for an internal combustion engine having an improved control system at start.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine of an intake pipe injection type in which a fuel injection valve is attached to an intake pipe, generally, asynchronous startup injection and group injection are performed at the time of starting, and fuel is injected in a stroke other than the intake stroke. I'm trying to start.

[0003]

However, since a part of the fuel injected at the time of starting adheres to the intake port and the intake valve,
As a result, the amount of fuel sucked into the combustion chamber becomes smaller than the required fuel injection amount. For this reason, in the initial stage of the start, the air-fuel ratio of the air-fuel mixture sucked into the combustion chamber becomes leaner than the combustible range, and the air-fuel mixture does not burn. HC) had the disadvantage of increasing the amount of emissions. After the start is completed, as the engine temperature increases, the fuel attached to the intake port and the like evaporates and is taken into the combustion chamber. Since the fuel amount is balanced, the above-described problem at the initial stage of the start does not occur.

The present invention has been made in view of such circumstances, and accordingly, an object of the present invention is to provide a start control device for an internal combustion engine capable of improving startability and reducing HC emission at start. To provide.

[0005]

In order to achieve the above-mentioned object, one feature of the present invention is that fuel injection is performed during the intake stroke at the time of starting by the starting injection timing control means. As a result, the injected fuel is directly sucked into the combustion chamber, and the amount of fuel attached to the intake port and the like is reduced, so that more fuel is supplied to the combustion chamber at the time of starting.

[0006] At the time of starting, since the temperature of the internal combustion engine is generally low, it is necessary to make the air-fuel mixture rich (to make the air-fuel ratio rich), and more fuel is required than after the start is completed. The increase in the fuel injection amount becomes the maximum, and the required fuel injection time becomes considerably long. Therefore, if the engine speed excessively rises due to combustion during the transition period from the start of cranking to the completion of the start, the opening time of the intake valve becomes considerably shorter than the required fuel injection time, and the amount of fuel required for the start Cannot be sufficiently supplied into the combustion chamber.

In view of this point, in the first aspect, when the fuel injection is performed during the intake stroke at the time of starting, the ignition timing is corrected by the rotation increase suppressing means so as to suppress the rotation increase within a predetermined range. That is, if the ignition timing is corrected to the retard side when the engine speed excessively increases at the time of starting, the engine speed decreases and the opening time of the intake valve (intake stroke) can be prolonged. As a result, even at a low temperature start, the fuel amount required for combustion can reliably flow into the combustion chamber. As a result, even at a low temperature start, the air-fuel ratio of the air-fuel mixture can be within the combustible range, the air-fuel mixture can be reliably burned, the startability can be improved, and the HC emission amount at the time of the start can be reduced. Can be reduced.

In this case, the increase in the engine speed at the time of starting is determined by the rotation increase determining means, and the opening of the intake valve required to allow the fuel amount required for starting to flow into the combustion chamber. The upper limit value of the rotation rise for securing the valve time (hereinafter referred to as "rotation rise upper limit value") is calculated by the rotation rise upper limit calculation means, and the rotation rise value is compared with the rotation rise upper limit value. The ignition timing may be corrected based on the rotation increase value to be equal to or less than the rotation increase upper limit value.
With this configuration, when the actual rotation increase value exceeds the rotation increase upper limit value, for example, as the difference between the two increases, the ignition timing retard correction amount is set to be large, and the decrease in the engine rotation speed is increased. As a result, the minimum necessary retardation correction amount corresponding to the difference between the actual rotation increase value and the rotation increase upper limit value (that is, the required rotation decrease width) can be set, and the ignition timing is retarded. Suppression of rotation rise by angle correction can be minimized.

Further, the engine speed may be detected, and a rotation increase value may be obtained from the engine speed. With this configuration, it is possible to obtain a rotation increase value reflecting the actual engine rotation speed in real time, and it is possible to accurately obtain an ignition timing correction amount corresponding to the actual rotation increase value.

Alternatively, the rotation increase value may be predicted based on at least the cooling water temperature of the internal combustion engine and the number of injections from the start of cranking. In this way, before the actual excessive rotation increase occurs,
It is possible to retard the ignition timing by predicting the rotation increase value and prevent an excessive rotation increase.

Incidentally, the temperature of the internal combustion engine at the time of starting varies depending on the cooling water temperature and the number of combustions since the start of cranking. As the temperature of the cooling water increases, and as the number of combustions increases from the start of cranking, the internal combustion engine increases. The required fuel injection amount at startup (required fuel injection time) because the temperature of the fuel increases and the amount of fuel injected (wet amount) into the intake port and the combustion chamber and the evaporation rate of the deposited fuel change accordingly. Also changes according to the temperature of the internal combustion engine.

Taking this point into consideration, the upper limit of the rotation increase may be set based on at least the cooling water temperature and the number of combustions from the start of cranking. By doing so, it is necessary to set an appropriate upper limit of the rotation increase and thus an appropriate opening time of the intake valve in response to a change in the temperature of the internal combustion engine and thus the required fuel injection amount according to the cooling water temperature and the number of combustions. Therefore, the engine speed can be smoothly increased toward the completion of the start.

Further, in the present invention, since the combustibility at the start can be improved by the intake stroke synchronous injection at the start and the rotation rise suppression control, it is estimated that the number of combustions increases as the number of injections from the start of cranking increases. it can. Therefore, instead of the number of combustions from the start of cranking, the number of injections from the start of cranking is used, and the rotation increase upper limit is set based on the number of injections and the coolant temperature. Is also good. It is necessary to detect the presence or absence of combustion at the time of starting, for example, by rotation fluctuation, combustion pressure in the combustion chamber, ion current, etc., but the number of injections can be determined only by counting the injection signal (injection pulse). It is extremely easy to count the number of injections. Therefore, if the rotation increase upper limit is set based on the number of injections from the start of cranking and the cooling water temperature, the processing or configuration relating to the setting of the rotation increase upper limit can be simplified.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS << Embodiment (1) >> An embodiment (1) in which the present invention is applied to a four-cylinder engine will be described below with reference to FIGS. First, a schematic configuration of the entire engine control system will be described with reference to FIG. A throttle valve 14 is provided in the middle of an intake pipe 13 connected to an intake port 12 of an engine 11 which is an internal combustion engine.
The opening (throttle opening) T of the throttle valve 14
A is detected by the throttle opening sensor 15. An intake pipe pressure sensor 18 for detecting an intake pipe pressure PM is provided downstream of the throttle valve 14, and a fuel injection valve 19 is attached near the intake port 12 of each cylinder.

On the other hand, in the middle of an exhaust pipe 21 connected to an exhaust port 20 of the engine 11, a catalyst 2 for purifying exhaust gas is provided.
2 are installed. The cylinder block of the engine 11 is provided with a cooling water temperature sensor 23 for detecting the cooling water temperature THW. A crank angle sensor 26 is installed facing the outer periphery of a signal rotor 25 fitted on a crank shaft 24 of the engine 11, and a pulse signal NE having a frequency corresponding to the rotation speed of the signal rotor 25 is output from the crank angle sensor 26. Is done.

The outputs of these various sensors are input to an engine control circuit (hereinafter referred to as "ECU") 27. The ECU 27 is mainly composed of a microcomputer, and is stored in a ROM (storage medium) shown in FIGS.
By executing each routine of FIGS. 6 and 9, the fuel injection valve 1 according to the engine operating state detected by various sensors
9 and the ignition timing of the ignition plug 17 via the ignition device 16.

Here, an outline of the starting control of the embodiment (1) will be described with reference to a time chart of FIG. The crank angle counter CCRNK detects a crank angle by counting pulse signals output from the crank angle sensor 26 at every 30 ° C., for example. Further, based on cylinder discrimination signals G1 and G2 output from a cylinder discrimination sensor (not shown), intake TDC (top dead center) of cylinder # 1 and intake TD of cylinder # 4 are determined.
C is detected to perform cylinder discrimination.

At the time of starting, after the cylinder discrimination is completed, an injection pulse is applied to the fuel injection valve 19 in the intake stroke of each cylinder based on the count value of the crank angle counter CCRNK to execute the fuel injection in the intake stroke. At the time of starting, since the engine temperature is generally low, it is necessary to enrich the air-fuel mixture (enrich the air-fuel ratio). Therefore, the fuel injection amount of the first cycle injection (-) is an increased value in consideration of the wet amount. Becomes For this reason, when the engine speed NE excessively increases due to the combustion (explosion) of the injected fuel as in the comparative example shown in FIG. 3, the intake stroke (valve opening time of the intake valve 28) is increased as in the injection. This is much shorter than the time (the width of the injection pulse). For this reason, in the injection, the fuel amount required for combustion cannot be sufficiently supplied into the combustion chamber, and the air-fuel mixture becomes leaner than the combustible range, causing misfiring, deteriorating startability and increasing HC emission. .

As a countermeasure against this, in this embodiment (1),
By retarding the ignition timing AOP so as to suppress the rotation increase of the engine 11 at the time of starting to be equal to or less than the rotation increase upper limit value β, the valve opening time (intake stroke) of the intake valve 28 is lengthened. Thereby, even if the opening time of the intake valve 28 at the time of starting is equal to or longer than the fuel injection time, or if the opening time of the intake valve 28 is shorter than the fuel injection time, the difference between the two is minimized.

Hereinafter, the processing contents of each routine for fuel injection / ignition control shown in FIGS. 4 to 6 and 9 executed by the ECU 27 will be described.

[Fuel Injection / Ignition Control Base Routine] The fuel injection / ignition control base routine shown in FIG. 4 is executed after an ignition switch (not shown) is turned on.
In this base routine, first, in step 100, an initialization routine is executed to set initial values in a storage area such as a RAM and to check various input signals. In the next step 200, the fuel injection amount calculation routine shown in FIG. 5 described below is executed to calculate the optimum fuel injection amount TAU using the engine operating state detected by the various sensors. The ignition timing AOP is calculated by executing the ignition timing calculation routine of FIG.

Thereafter, the routine proceeds to step 400, in which the fuel injection is performed in the intake stroke with the fuel injection amount TAU obtained in step 200, and in the next step 500, step 300 is executed.
The ignition is performed at the ignition timing AOP determined in step (1). During the operation of the engine, the processing after step 200 is repeatedly executed.

[Fuel Injection Amount Calculation Routine] The fuel injection amount calculation routine shown in FIG. 5 (step 200 in FIG. 4) is executed by interrupt processing every time a crank signal is input from the crank angle sensor 26 (every 30 ° C. A). Is performed as follows. First, in step 201, the cooling water temperature THW, the engine speed NE, and the intake pipe pressure P detected by various sensors.
Read M. Thereafter, in step 202, it is determined whether or not the engine is at the start. This start determination is made based on, for example, whether the engine speed NE is equal to or less than the start completion speed. If it is determined in step 202 that the starting is completed, the routine proceeds to step 207, where the post-starting fuel injection amount TAU is calculated, and this routine ends.

On the other hand, if it is determined in step 202 that the engine has been started (before the start is completed), the flow advances to step 203 to read the number of injection cycles CCYCL from the start of cranking. The injection cycle number CCYCL is counted by the injection cycle number calculation routine shown in FIG. This injection cycle number calculation routine is executed, for example, every 18 ms as follows. First, at step 210, it is determined whether or not the injection processing has been completed. If the injection processing has been completed, the routine proceeds to step 211, where the injection number counter CINJ is incremented by “1”, and then the processing proceeds to step 212. Then, the injection cycle number CCYCL is calculated by the following equation.

CCYCL = CINJ / 4 + 1 In the above equation, "4" is the number of cylinders of the engine 11,
Four injections are converted into one cycle, and “1” is added to make the first cycle the first cycle.

After reading the injection cycle number CCYCL, the process proceeds from step 203 to step 204 in FIG.
A map of the basic fuel injection amount at the start TAUST using the injection cycle number CCYCL as a parameter shown in FIG. 7 is searched,
A starting basic fuel injection amount TAUST corresponding to the current injection cycle number CCYCL is determined. In general, the injected fuel has a greater amount of wetness attached to the intake port and the inner wall surface of the cylinder at an early stage of the start (that is, as the engine temperature is lower). In order to correct this wet amount, the basic fuel injection amount T at the time of starting shown in FIG.
The map characteristic of AUST is set such that the smaller the injection cycle number CCYCL, the larger the starting basic fuel injection amount TAUST.

In the next step 205, a map of the cooling water temperature correction coefficient FTHW using the cooling water temperature THW as a parameter shown in FIG. 8 to correct the change in the wet amount and the evaporation time constant of the injected fuel due to the change in the cooling water temperature. And a cooling water temperature correction coefficient FTHW corresponding to the current cooling water temperature THW.
Ask for. The map characteristic of the cooling water temperature correction coefficient FTHW is set such that, in a region where the cooling water temperature THW is low, the cooling water temperature correction coefficient FTHW is increased as the cooling water temperature THW is lowered, so that the basic fuel injection amount TAUST at start is increased and corrected. In a region where the cooling water temperature is high, the cooling water temperature correction coefficient FTHW is reduced as the cooling water temperature increases,
The starting basic fuel injection amount TAUST is set so as to be reduced.

Thereafter, the routine proceeds to step 206, in which the starting fuel injection amount TAU is calculated by multiplying the starting basic fuel injection amount TAUST by the coolant temperature correction coefficient FTHW (TAU = TAU = TAU = TAUW).
TAUST × FTHW), and terminates this routine.

[Ignition Timing Calculation Routine] In the ignition timing calculation routine shown in FIG. 9 (step 300 in FIG. 4), first, in step 301, the coolant temperature THW, the engine speed NE and the intake pipe pressure PM are read. Step 3
At 02, for example, it is determined whether or not the engine has been started based on the engine speed NE.

If it is determined in step 302 that the start has been completed, the process proceeds to step 311 to calculate the ignition timing AOP of the normal ignition control after the start has been completed, and terminates this routine. On the other hand, if it is determined in step 302 that the engine has been started (before the start is completed), the process proceeds to step 303, and FIG.
A starting time ignition timing AST corresponding to the current cooling water temperature THW is obtained by searching a map of the starting ignition timing AST using the cooling water temperature THW as a parameter shown in FIG.

Thereafter, in steps 304 to 310, in order to secure the opening time of the intake valve at the time of starting, the ignition timing AST at the starting time is controlled so that the rotation increase of the engine 11 at the start is suppressed to the rotation increase upper limit β or less. Is retarded. In particular,
First, at step 304, for each combustion (explosion) timing,
Engine speed N from last combustion to current combustion
The deviation of E, that is, the rotation increase value DNE is calculated, and it is determined whether or not the rotation increase value DNE is larger than the combustion determination value α (see FIG. 11). The process of step 304 functions as a rotation increase determination unit described in the claims.

Here, the combustion determination value α is a rotation increase value at a level that leads to continuous explosion. The combustion determination value α may be a fixed value set in advance, but it is taken into consideration that the engine speed NE near the explosion stroke of each cylinder is affected by a change in the battery voltage due to the engine temperature and a change in the viscosity of the engine oil. Then, the combustion determination value α may be set according to the cooling water temperature THW at the time of starting using a map using the cooling water temperature THW (engine temperature) as a parameter shown in FIG.

If it is determined in step 304 that the rotation rise value DN
If it is determined that E is not at a level that will lead to continuous explosion (DNE ≦ α), the routine proceeds to step 312, where the number of combustion counter C
Clear FIRE (CFIRE = 0), step 30
The starting ignition timing AST obtained in 3 is maintained as it is.

On the other hand, if it is determined in step 304 that the rotation increase value DNE is a level (DNE> α) leading to continuous explosion, the process proceeds to step 305, where the count value of the combustion number counter CFIRE is increased by one. Increment. As a result, the number of times the continuous explosion level combustion has occurred since the start of cranking is counted by the combustion number counter CFIRE.

Thereafter, in step 306, a rotation rise upper limit β which is a guard value at the time of starting the rotation rise value DNE is calculated based on the number of combustions (CFIRE) from the start of cranking and the coolant temperature THW. The process of step 306 functions as a rotation rise upper limit value calculating means described in claims 2 and 5 of the claims. Here, the rotation increase upper limit value β is a rotation increase that can secure an intake valve opening time (hereinafter, referred to as a “required intake valve opening time”) required to allow a fuel amount necessary for a continuous explosion to flow into the combustion chamber. This is the upper limit value, and the characteristic line of the rotation increase upper limit value β using the number of combustions (CFIRE) shown in FIG. The characteristic line of the rotation increase upper limit β is selected, and the rotation increase upper limit β corresponding to the number of combustions (CFIRE) is obtained from the characteristic line.

In general, the higher the cooling water temperature THW and the greater the number of combustions (CFIRE) from the start of cranking, the higher the engine temperature, the smaller the required fuel injection amount, and the shorter the fuel injection time (injection pulse). Width) becomes shorter. Considering this point, the map characteristic of the rotation rise upper limit value β in FIG. 13 shows that the rotation rise upper limit value β increases as the cooling water temperature THW increases and as the number of times of combustion (CFIRE) increases. (The valve opening time is short.) In addition, as the number of combustions (CFIRE) increases, the starting completion time is approached.
If the rotation increase upper limit β is increased with an increase in the number of combustions (CFIRE), the engine speed NE can be smoothly increased to the start completion rotation speed. This figure 1
The map of the rotation increase upper limit β of No. 3 is set in advance by experimental data and theoretical formulas, and is stored in the ROM of the ECU 27.

After calculating the rotation increase upper limit value β, step 30
At 7, it is determined whether or not the rotation increase value DNE is larger than the rotation increase upper limit β. If the rotation increase value DNE is equal to or less than the rotation increase upper limit value β, the necessary intake valve opening time can be secured, so that the subsequent ignition timing retard correction (rotation increase suppression) is not performed, and the starting calculated in step 303 is performed. Ignition timing AST
Is maintained.

On the other hand, if it is determined in step 307 that the rotation increase value DNE is larger than the rotation increase upper limit value β, the process proceeds to step 308, where the rotation increase upper limit value β is subtracted from the rotation increase value DNE. An over value γ is obtained (γ = DNE-β). Thereafter, in step 309, FIG.
A search is made for a map of the ignition retard correction value FAOP using the guard over value γ as a parameter shown in FIG. 4, and according to the guard over value γ, the ignition retard correction value FAOP for suppressing the rotation increase to the rotation increase upper limit β or less. Ask for. Thereafter, at step 310, the ignition timing at start AST obtained at step 303 is retarded by the ignition retard correction value FAOP to obtain the final ignition timing AOP at start (AOP = AST-FAO).
P), this routine ends.

As described above, from the start of cranking to the completion of the start, the rotation increase is guarded by the rotation increase upper limit value β, and the intake valve necessary to allow the fuel amount necessary for the continuous explosion to flow into the combustion chamber is opened. Secure valve time.

According to the embodiment (1) described above, the fuel injection is performed during the intake stroke at the time of starting.
The injected fuel is directly sucked into the combustion chamber, and the adhesion of the fuel to the intake port 12 and the like can be reduced.
To that extent, more fuel can be supplied into the combustion chamber than before in the startup.

In addition, when the engine speed is excessively increased at the time of starting, the ignition timing is corrected by retarding the ignition timing so as to suppress the rotation increase to be equal to or less than the rotation increase upper limit value β. The opening time of the intake valve required to allow the fuel amount to flow into the combustion chamber can be secured, and the fuel amount required for continuous explosion can be reliably flown into the combustion chamber even at a low temperature start. As a result, even at the time of low-temperature start, the air-fuel ratio of the air-fuel mixture can be set within a range in which consecutive explosions can be performed, so that startability can be improved and HC emission at the time of start can be reduced.

Further, in the embodiment (1), only when the rotation increase value DNE is larger than the rotation increase upper limit β (that is, when the required intake valve opening time cannot be secured), the rotation increase value DNE and the rotation increase upper limit Since the ignition retard correction value FAOP is set in accordance with the difference from the value β, the necessary minimum ignition retard correction value FAOP can be set, and the ignition timing retard correction (rotation increase suppression) Can be minimized, and it is possible to prevent excessive increase in rotation during startup. The rotation increase value DNE and the rotation increase upper limit β
Instead of the difference (DNE-β), the ratio (DNE /
The ignition retard correction value FAOP may be set according to β).

<< Embodiment (2) >> Next, an embodiment (2) of the present invention will be described with reference to FIGS. In the embodiment (1), the ignition timing is retarded by calculating the actual rotation increase value DNE from the engine speed NE detected by the crank angle sensor 26. However, in the embodiment (2), the cooling is performed. The rotation rise value DNE is predicted from the water temperature and the number of injections from the start of cranking, and the ignition timing is retarded.

The fuel injection / ignition control base routine of FIG. 15 executed in the embodiment (2) is the same as that of the embodiment (1) except for step 250 (rotation rise prediction) and step 300a (calculation of ignition timing). This is the same as the fuel injection / ignition control base routine of FIG.

In this base routine, after the initialization processing, the fuel injection amount is calculated (steps 100 and 200), and a rotation increase prediction routine shown in FIG. 16 described later is executed, and the rotation is calculated from the cooling water temperature THW and the number of injections CINJ. The rise value DNE is predicted (step 250). The processing of the rotation increase prediction routine functions as rotation increase determination means described in claim 4 of the present invention. Thereafter, an ignition timing is calculated by executing an ignition timing calculation routine of FIG. 18 described later (step 300a), and fuel injection and ignition are executed (steps 400 and 500).

A rotation rise prediction routine shown in FIG. 16 (FIG. 1)
In step 250 of 5), first, in step 251,
After reading the number of injections CINJ from the start of cranking, in step 252, the cooling water temperature THW is read. In the next step 253, a rotation rise value DNE characteristic corresponding to the cooling water temperature THW is obtained by using a map in which a plurality of characteristic curves of the rotation increase value DNE using the number of injections CINJ shown in FIG. 17 as parameters are set according to the cooling water temperature THW. A curve is selected, and a rotation increase value DNE corresponding to the number of injections CINJ is obtained from the characteristic curve. At start-up, the first injected fuel is
Since the combustion (explosion) stroke is reached after the elapse of 360 ° C. A (two injections), the rising point of the rotation increase value DNE characteristic curve is CINJ = 3. The map of the rotation increase value DNE is set in advance by experimental data and theoretical formulas,
It is stored in the ROM of the CU 27.

An ignition timing calculation routine shown in FIG. 18 (FIG. 1)
In step 300a) of step 5, steps 305 and 312 (processing of the number-of-combustion counter) are omitted from the ignition timing calculation routine of FIG. 9 to calculate the rotation increase upper limit β (step 30).
The map used in 6a) is changed, and the other processing is the same as the ignition timing calculation routine in FIG. In step 304, if the rotation increase value DNE predicted by the rotation increase prediction routine in FIG. 16 is larger than the combustion determination value α, the process proceeds to step 306a, and the rotation is performed based on the number of injections CINJ from the start of cranking and the coolant temperature THW. The rise upper limit value β is obtained. At this time, as shown in FIG. 19, using a map in which a plurality of characteristic lines of the rotation rise upper limit value β using the number of injections CINJ as a parameter in accordance with the cooling water temperature THW, a rotation corresponding to the cooling water temperature THW at the time of start-up Select the rise upper limit β characteristic line, and select the injection number CI from the characteristic line.
A rotation increase upper limit β corresponding to NJ is obtained. The map of the rotation increase upper limit value β is set in advance by experimental data and theoretical expressions, and is stored in the ROM of the ECU 27. The processing of step 306a functions as a rotation rise upper limit value calculation means described in claims 2 and 6 of the claims.

Thereafter, when the predicted rotation increase value DNE is larger than the rotation increase upper limit value β, that is, when it is predicted that the necessary intake valve opening time cannot be secured, the rotation increase guard over value γ (= After the ignition retard correction value FAOP according to (DNE-β) is obtained, the ignition timing AST at the start is corrected by the ignition retard correction value FAOP to obtain the final ignition timing AOP at the start (steps 307 to 310). .

In the embodiment (2) described above, FIG.
As shown in the figure, before the excessive rotation increase actually occurs,
The rotation increase value DNE is predicted, and the guard over value γ (=
Since the ignition timing AOP can be retarded by calculating the ignition retard correction value FAOP according to (DNE-β), it is possible to prevent an excessive increase in rotation from the first combustion at the start.

In this embodiment (2), the rotation increase upper limit β is determined from the number of injections CINJ and the cooling water temperature THW. However, as in the first embodiment, the number of combustion CFIRE and the cooling water temperature THW are obtained. From this, the rotation increase upper limit β may be obtained. In addition to the cooling water temperature THW and the number of combustions CFIRE (or the number of injections CINJ), for example, an intake air temperature (or an outside air temperature) may be added as a parameter used for calculating the rotation increase upper limit β.

In addition, the present invention can be variously modified and implemented without departing from the gist, such as being applicable to an engine having a number of cylinders other than four cylinders.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system according to an embodiment (1) of the present invention.

FIG. 2 is a time chart for explaining a control behavior at the time of starting according to the embodiment (1).

FIG. 3 is a time chart for explaining a control behavior at the time of starting in a comparative example.

FIG. 4 is a flowchart showing the flow of processing of a fuel injection / ignition control base routine according to the embodiment (1).

FIG. 5 is a flowchart showing the flow of processing of a fuel injection calculation routine;

FIG. 6 is a flowchart showing a processing flow of an injection cycle number calculation routine.

FIG. 7 is a diagram showing a map defining a relationship between the number of injection cycles CCYCL and a basic fuel injection amount at start TAU.

FIG. 8 is a diagram showing a map defining a relationship between a cooling water temperature THW and a cooling water temperature correction coefficient FTHW.

FIG. 9 is a flowchart showing a process flow of an ignition timing calculation routine according to the embodiment (1).

FIG. 10 is a view showing a map defining a relationship between a cooling water temperature THW and a starting ignition timing AST.

FIG. 11 is a diagram for explaining a method of determining rotation increase;

FIG. 12 is a view showing a map defining a relationship between a cooling water temperature THW and a combustion determination value α.

FIG. 13 is a diagram showing a map defining a relationship between the number of combustion times CFIRE, a rotation rise upper limit value β, and a cooling water temperature THW.

FIG. 14 shows a guard over value γ and an ignition retard correction value FAOP.
Figure showing a map that defines the relationship with

FIG. 15 is a diagram showing fuel injection and fuel injection according to embodiment (2) of the present invention.
Flow chart showing the flow of processing of the ignition control base routine

FIG. 16 is a flowchart showing the flow of processing of a rotation rise prediction routine.

FIG. 17 is a diagram showing a map defining a relationship among the number of injections CINJ, a rotation rise value DNE, and a cooling water temperature THW.

FIG. 18 is a flowchart showing the flow of processing of an ignition timing calculation routine according to the embodiment (2).

FIG. 19 is a diagram showing a map that defines a relationship among the number of injections CINJ, a rotation rise upper limit value β, and a cooling water temperature THW.

FIG. 20 is a time chart for explaining a control behavior at the time of starting according to the embodiment (2).

[Explanation of symbols]

11: engine (internal combustion engine), 13: intake pipe, 17: spark plug, 19: fuel injection valve, 23: cooling water temperature sensor,
26 ... crank angle sensor, 27 ... ECU (start-up injection timing control means, rotation rise suppression means, rotation rise determination means, rotation rise upper limit value calculation means), 28 ... intake valve.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI F02P 5/15 F02P 5/15 E

Claims (6)

[Claims] 1. A start control device for an internal combustion engine for injecting fuel from a fuel injection valve for each cylinder of the internal combustion engine, wherein fuel injection of each cylinder is executed during an intake stroke of each cylinder at the time of start. A start-up control device for an internal combustion engine, comprising: a start-up control unit that corrects an ignition timing so that the start-up of the internal combustion engine is suppressed within a predetermined range at the time of starting. 2. A rotation increase determining means for determining an increase in engine speed at the time of starting, and a rotation increase for securing an intake valve opening time required for flowing a fuel amount necessary for starting into the combustion chamber. A rotation rise upper limit value calculating means for calculating an upper limit value (hereinafter referred to as a “rotation rise upper limit value”), wherein the rotation rise suppression means includes a rotation rise value determined by the rotation rise determination means and the rotation rise upper limit. The ignition timing is corrected so as to compare the rotation increase value calculated by the value calculation means with the rotation increase upper limit value and to suppress the rotation increase value to the rotation increase upper limit value or less based on the comparison result. A start control device for an internal combustion engine according to claim 1. 3. The start control device for an internal combustion engine according to claim 2, wherein the rotation increase determination means detects an engine rotation speed and obtains the rotation increase value from the engine rotation speed. 4. The internal combustion engine according to claim 2, wherein the rotation increase determination means predicts the rotation increase value based on at least a cooling water temperature of the internal combustion engine and the number of injections from the start of cranking. Engine start control. 5. The rotation increase upper limit value calculating means sets the rotation increase upper limit value based on at least a cooling water temperature of the internal combustion engine and the number of combustions from the start of cranking. 4. The start control device for an internal combustion engine according to claim 1. 6. The rotation increase upper limit value calculating means sets the rotation increase upper limit value based on at least a cooling water temperature of the internal combustion engine and the number of injections from the start of cranking. 4. The start control device for an internal combustion engine according to claim 1.