JPH09112395A - Ignition control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of the overload of an ignition coil and to increase ignition energy by a method wherein a lapse time after an energizing time of an ignition coil is extended is clocked, and when a lapse time exceeds a set time, extension of the energizing time of the ignition coil is stopped. SOLUTION: A detecting signal from a sensor switch inputted through an I/O interface 46 and a battery voltage are processed according to a control program stored at an ROM 42 by a CPU 41. Based on various data contained at an ROM 43 and a backup RAM 44 and fixed data stored at the ROM 42, a lapse time after the energizing time of an ignition coil 15b is extended is clocked by a counter timer group 45. When the lapse time exceeds a set time, extension of the energizing time of the ignition coil 15b is suspended. This constitution increases ignition energy as the overload of the ignition coil 15b is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition control device for an engine for controlling ignition time of an ignition coil to increase ignition energy.

[0002]

2. Description of the Related Art Generally, in a spark ignition engine,
Ignition devices that apply a secondary high voltage generated when the primary current of the ignition coil is interrupted to a spark plug to discharge it are widely adopted, but the ignition energy required to secure stable combustion is: It changes depending on the combustion method and operating conditions.

For example, exhaust gas recirculation (EG) for recirculating a part of the exhaust gas of the engine to the intake side to lower the combustion temperature of the air-fuel mixture to reduce nitrogen oxides (NOX) in the exhaust gas.
A large amount of R) and a lean burn engine that performs combustion with a lean mixture require a large amount of ignition energy to ensure stable combustion.

For this reason, various techniques for increasing the ignition energy have been proposed in the past, and JP-A-60-220 has been proposed.
Japanese Unexamined Patent Publication No. 72-72 discloses a technique of increasing the energization time by accelerating the energization start timing of the engine in accordance with the acceleration state of the engine as compared with the steady state, and also in JP-A-62-62
No. 174566 discloses that the maximum energization time of the ignition coil is determined, the energization current of the ignition coil is detected, and the maximum closed circuit rate (closed circuit rate: ratio of ignition coil energized time to ignition cycle) is determined by the engine operating condition and the battery. A technique of changing the voltage is disclosed.

[0005]

However, the prior art is to control the primary current of the ignition coil for each ignition, so that the ignition energy is increased when it is necessary to increase the ignition energy according to the operating condition. Since the coil energization time is set longer than usual, if the operating state in which the required ignition energy is large continues for a long time, the ignition coil may be overloaded.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an ignition control device for an engine capable of increasing ignition energy while preventing overload of the ignition coil.

[0007]

According to the first aspect of the present invention,
As shown in the basic configuration diagram of FIG. 1, ignition setting means for setting the energization time and the energization interruption timing of the ignition coil based on the crank position of the engine, and extending the energization time of the ignition coil under the set operating condition. An energization time extension means and an energization time restoration means for measuring the elapsed time after the energization time of the ignition coil is extended and stopping the extension of the energization time of the ignition coil when the elapsed time exceeds a set time It is characterized by having and.

According to a second aspect of the present invention, in the invention according to the first aspect, the set operating state is an operating state based on combustion control of a lean air-fuel mixture, and the energizing time returning means sets the energizing time of the ignition coil. When the extension is stopped, the combustion control of the lean air-fuel mixture is stopped at the same time.

According to a third aspect of the present invention, in the first aspect of the present invention, the set operating state is an operating state in which exhaust gas recirculation of a set amount or more is performed, and the energization time returning means is provided for the ignition coil. When the extension of the energization time is stopped, at the same time, the exhaust gas recirculation of a set amount or more is stopped.

That is, according to the first aspect of the present invention, under the set operating condition, ignition energy is increased by extending the energization time of the ignition coil to perform ignition, and when the set time elapses, the energization time extension is stopped. And protect the ignition coil.

In this case, as described in claim 2, under the operating condition by the lean air-fuel mixture combustion control, the lean air-fuel mixture combustion control is stopped at the same time when the ignition coil energization time is extended and stopped. As described in item 3, under the operating condition in which a large amount of exhaust gas recirculation of the set amount or more is performed, the exhaust gas recirculation of a large amount of the set amount or more is stopped at the same time as the extension of the ignition coil energization time is stopped.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The drawings show an embodiment of the present invention, FIG. 2 is a flowchart of a dwell extension execution / stop determination routine, FIG. 3 is a flowchart of a cylinder determination / engine speed calculation routine, FIG. 4 is a flowchart of a fuel injection amount setting routine, 5 is a flowchart of the EGR control routine, FIG. 6 is a flowchart of the ignition control routine, FIG. 7 is a flowchart of the θ1 crank pulse interrupt routine, FIG. 8 is a flowchart of the TDWL interrupt routine, and FIG. 9 is a flowchart of the θ2 crank pulse interrupt routine. 10 is a flowchart of the TADV interrupt routine,
11 is an ignition timing chart, FIG. 12 is a schematic configuration diagram of an engine control system, FIG. 13 is a front view of a crank rotor and a crank angle sensor, FIG. 14 is a front view of a cam rotor and a cam angle sensor, and FIG. 15 is an electronic control system. 2 is a circuit configuration diagram of FIG.

In FIG. 12, reference numeral 1 is an engine, and in the figure, a horizontally opposed four-cylinder engine is shown. Cylinder heads 2 are provided on both left and right banks of a cylinder block 1a of the engine 1, and an intake port 2a and an exhaust port 2b are formed on each cylinder head 2.

An intake manifold 3 is connected to the intake port 2a, and an intake pipe 5 is connected to the intake port 2a through an air chamber 4 formed at an upstream side collecting portion of the intake manifold 3. On the other hand, in the exhaust port 2b,
An exhaust pipe 7 is connected through the exhaust manifold 6, and a catalytic converter 8 is inserted in the exhaust pipe 7 and is connected to a muffler 9.

An air cleaner 10 is attached to the upstream side of the intake pipe 5 on the side of the air intake, and a throttle valve 11 is interposed midway. Furthermore, in the intake pipe 5,
Bypass passage 12 that bypasses the throttle valve 11
Is connected, and an idle speed control valve (ISCV) 13 is interposed in the bypass passage 12.

Further, an injector 14 is provided immediately upstream of each intake port 2a of each cylinder of the intake manifold 3.
A spark plug 15a, the tip of which is exposed to the combustion chamber, is attached to each cylinder of the cylinder head 2. An igniter 16 is connected to the ignition plug 15a via an ignition coil 15b arranged for each cylinder.

On the other hand, reference numeral 17 is an EGR passage, one end of which is connected to at least one exhaust port 2b formed in the cylinder head 2, and the other end is connected to the air chamber 4. . An EGR valve 18 composed of a diaphragm actuator is provided in the middle of the EGR passage 17.

The EGR valve 18 is provided in the EGR passage 17
18a for opening and closing the valve and the valve 1 by the diaphragm
The pressure chamber 18b is partitioned from the 8a side and stores a spring for urging the valve element 18a in the valve closing direction. The pressure chamber 18b communicates with the intake pipe 5 immediately downstream of the throttle valve 11 via a control pressure passage 19, and an EGR control duty solenoid valve 20 is provided in the control pressure passage 19.

The EGR control duty solenoid valve 20 is an electromagnetic three-way valve having a port communicating with the control pressure passage 19, a port communicating with the pressure chamber of the EGR valve 18, and a port communicating with the atmosphere side. The control pressure passage 1 according to the duty ratio of the control signal output from the electronic control unit 40 (ECU 40; see FIG. 15) described later.
The valve opening of the port communicating with 9 is adjusted, and the intake pipe 5
The pressure on the side and the atmospheric pressure are adjusted, and the control pressure is supplied to the pressure chamber 18b of the EGR valve 18.

In the present embodiment, the smaller the duty ratio of the control signal output to the EGR control duty solenoid valve 20, the smaller the valve opening of the port communicating with the control pressure passage 19 and the EGR valve 18 described above. Pressure chamber 1
The control pressure supplied to 8b becomes close to the atmospheric pressure, and
The opening degree of the R valve 18 becomes smaller and the EGR amount decreases. On the other hand, as the duty ratio of the control signal output to the EGR control duty solenoid valve 20 increases, the valve opening degree of the port communicating with the control pressure passage 19 increases, and the pressure chamber 18b of the EGR valve 18 increases. A high negative pressure is supplied, the valve opening of the EGR valve 18 increases, and the EGR amount increases.

Next, the arrangement of the sensors will be described.
Reference numeral 21 is a thermal type intake air amount sensor using a hot wire or a hot film or the like, and is provided in the intake pipe 5 immediately downstream of the air cleaner 10. Further, the throttle valve 11 is provided with a throttle sensor 22 in which a throttle opening sensor 22a and an idle switch 22b which is turned on when the throttle is fully closed are incorporated.

Further, a knock sensor 23 is attached to the cylinder block 1a of the engine 1, and a cooling water temperature sensor 24 is exposed to a cooling water passage 1d which connects the left and right banks of the cylinder block 1a to the exhaust pipe 7.
A wide-range air-fuel ratio sensor 25 faces the upstream side of the catalytic converter 8. Further, the crank angle sensor 27 is provided on the outer periphery of the crank rotor 26 that is axially attached to the crankshaft 1b.
Further, a cam angle sensor 29 for cylinder discrimination is provided opposite to a cam rotor 28 which is provided continuously with the cam shaft 1c.

As shown in FIG. 13, the crank rotor 26 has protrusions 26a, 26b and 26c formed on the outer periphery thereof, and these protrusions 26a, 26b and 26c are associated with the cylinders (# 1, # 2 and #). Before # 3, # 4 compression top dead center (BTD
C) It is formed at the positions of θ1, θ2, and θ3. In this embodiment, θ1 = 97 ° CA, θ2 = 65 ° CA, and θ3 = 1.
0 ° CA.

Further, as shown in FIG. 14, on the outer circumference of the cam rotor 28, there are projections 28a, 28b for cylinder discrimination,
28c is formed, and the protrusion 28a is formed at the position after compression top dead center (ATDC) θ4 of the # 3 and # 4 cylinders.
b is composed of three protrusions, and the first protrusion is A of the # 1 cylinder.
It is formed at the position of TDC θ5. Further, the protrusion 28
c is formed by two protrusions, and the first protrusion is A for cylinder # 2.
It is formed at the position of TDC θ6. In this embodiment, θ4 = 20 ° CA, θ5 = 5 ° CA, θ6 = 20 ° C.
A.

Then, as shown in the timing chart of FIG. 11, each protrusion of the crank rotor 26 is detected by the crank angle sensor 27, and θ1, θ2, θ3 (B
While the crank pulse of TDC 97 °, 65 °, 10 °) is output for every 1/2 engine revolution (every 180 ° CA), each protrusion of the cam rotor 28 is between the θ3 crank pulse and the θ1 crank pulse. The cam angle sensor 29 detects and outputs a predetermined number of cam pulses.

As will be described later, the ECU 40 calculates the engine speed NE based on the input interval time of the crank pulse output from the crank angle sensor 27, and the combustion stroke order of each cylinder (for example, # 1 cylinder → #
(3 cylinder → # 2 cylinder → # 4 cylinder) and the cam angle sensor 2
Based on the pattern of the cam pulse from No. 9 and the value counted by the counter, cylinder discrimination of the fuel injection target cylinder and the ignition target cylinder is performed.

As shown in FIG. 15, the ECU 40 is
CPU 41, ROM 42, RAM 43, backup R
An AM 44, a counter / timer group 45, and an I / O interface 46 are mainly configured by a microcomputer connected to each other via a bus line 47, and a constant voltage circuit 47 for supplying a stabilized power source to each unit, the I / O described above. A drive circuit 48 and A / connected to the interface 46
Peripheral circuits such as the D converter 49 are built in.

The counter / timer group 45 is used for various counters such as a free-run counter, a counter for counting input of cam angle sensor signals, a fuel injection timer, an ignition timer, and a periodic interrupt for generating a periodic interrupt. Various timers, such as a timer, a crank interval sensor signal input interval timing timer, and a watchdog timer for system abnormality monitoring, are generically referred to for convenience, and various software counter timers may also be used. .

The constant voltage circuit 47 is connected to the battery 51 via the first relay contact of the power supply relay 50 having two relay contacts, and the battery 51 is also connected.
Is connected directly to the O of the ignition switch 52.
Regardless of N or OFF, the backup RAM 44 is always supplied with power for backup.
Further, one end of a relay coil of the power supply relay 50 is connected to the battery 51 via the ignition switch 52, and the other end of the relay coil is grounded.

The idle switch 22b and the knock sensor 2 are connected to the input port of the I / O interface 46.
3, a crank angle sensor 27, a cam angle sensor 29 are connected, and further, an intake air amount sensor 21, a throttle opening sensor 22a, a cooling water temperature sensor 24, and a wide area are provided via the A / D converter 49. The air-fuel ratio sensor 25 is connected and the battery voltage VB is input and monitored.

On the other hand, at the output port of the I / O interface 46, the ISCV 13, injector 14, E
The GR control duty solenoid valve 20 is connected via the drive circuit 48, and # 1, # 2, # 3 are connected.
An igniter 16 composed of four power transistors for driving each ignition coil 15b of the # 4 cylinder is connected.

The power supply + V to the primary side of each ignition coil 15b is connected to a power supply line extending from the battery 51 through the second relay contact of the power supply relay 50 to supply power to each actuator. It is connected.

The CPU 41 processes the detection signals from the sensors and switches input via the I / O interface 46, the battery voltage, etc. according to the control program stored in the ROM 42, and the RAM 4
3 and various data stored in the backup RAM 44, fixed data stored in the ROM 42, and the like, the fuel injection amount, the ignition timing, the duty ratio of the drive signal for the EGR control duty solenoid valve 20, IS
Calculate the duty ratio of the drive signal for CV13,
Engine control such as air-fuel ratio control, ignition timing control, EGR control, idle speed control, etc. is performed.

In this engine control, in order to save fuel consumption, the air-fuel ratio control for stoichio in a normal air-fuel mixture is switched to the air-fuel ratio control by lean combustion, that is, lean burn control, depending on the operating region, and the exhaust gas is also controlled. N in
In order to reduce the amount of OX emissions as much as possible, a large amount of EGR (high EGR) is implemented depending on the operating region.
During lean burn control or high EGR control, a large amount of ignition energy is required as compared with normal control because the ignition performance of the air-fuel mixture is poor.

Therefore, the ECU 40 ensures the required ignition energy according to the operating state of the engine and prevents the ignition coil 15b from being overloaded due to the increase of the ignition energy. The functions of the ignition setting means, the energization time extending means, and the energization time restoring means according to the present invention are realized by the sensors and actuators connected to the ECU 40.

The process relating to the increase in ignition energy during lean burn control or high EGR control will be described below with reference to the flowcharts shown in FIGS.

First, the ignition switch 52 is turned on.
Then, when power is supplied to the ECU 40, the system is initialized and each flag and each counter are initialized. When a starter switch (not shown) is turned on and the engine is operated, the cylinder discrimination / engine speed calculation routine shown in FIG. 3 is started each time a crank pulse is input from the crank angle sensor 27.

In this cylinder discrimination / engine speed calculation routine, when the crank rotor 26 rotates with engine operation and a crank pulse is input from the crank angle sensor 27, first, in step S101, the crank pulse input this time is input. Is determined as a signal corresponding to a crank angle of θ1, θ2, or θ3 based on the input pattern of the cam pulse from the cam angle sensor 29, and in step S102, the fuel injection target cylinder is determined from the input pattern of the crank pulse and the cam pulse. Determine.

That is, as shown in the timing chart of FIG. 11, for example, if there is a cam pulse input between the previous crank pulse input and the current crank pulse input, the current crank pulse is θ1 crank. It can be identified as a pulse, and the crank pulse to be input next time can be identified as a θ2 crank pulse.

If there is no cam pulse input between the crank pulse inputs of the previous time and this time, and there is a cam pulse input between the crank pulse inputs of the time before two times and the previous time, the current crank pulse can be identified as a θ2 crank pulse, The crank pulse input next time can be identified as the θ3 crank pulse. In addition, when there is no cam pulse input between the previous time and this time, and between the crank pulse input two times before and the previous time, the crank pulse input this time can be identified as the θ3 crank pulse, and the crank pulse input next time is It can be identified as θ1 crank pulse.

Furthermore, three cam pulses are input between the crank pulse input of the previous time and the crank pulse input of the present time (θ corresponding to the protrusion 28b).
It is possible to determine that the next compression top dead center is the # 3 cylinder, and the fuel injection target cylinder is the # 4 cylinder, which is two cylinders after that, when the cam pulse is 5). Further, when two cam pulses are input (θ6 cam pulse corresponding to the protrusion 28c) between the crank pulse inputs of the previous time and this time, the next compression top dead center is the # 4 cylinder and the fuel injection target cylinder is the # 4 cylinder.
It can be identified as 3 cylinders.

Further, one cam pulse is input between the crank pulse input at the previous time and the crank pulse input at this time (θ4 corresponding to the protrusion 28a).
When the previous compression top dead center determination is the # 4 cylinder, the next compression top dead center is the # 1 cylinder, and the fuel injection cylinder can be determined to be the # 2 cylinder. Similarly, when one cam pulse is input between the crank pulse inputs of the previous time and this time and the previous compression top dead center determination is # 3 cylinder, the next compression top dead center is # 2 cylinder, and the fuel injection is performed. The target cylinder can be identified as the # 1 cylinder.

In the four-cycle four-cylinder engine 1 of the present embodiment, the combustion stroke is in the order of cylinders # 1 → # 3 → # 2 → # 4, and the cylinder #i which becomes the compression top dead center after the output of the cam pulse is #.
If one cylinder is used, the fuel injection target cylinder #i (+2) at this time
Is the # 2 cylinder, the next fuel injection target cylinder is the # 4 cylinder, and the fuel injection is performed once for every 720 ° CA (two engine revolutions).

After that, the above steps S102 to S1
In step 03, the pulse input interval time (for example, θ1 crank pulse and θ2 crank pulse input interval time) between the previous crank pulse input and the current crank pulse input is measured, and the rotation cycle f is determined. Find, step S1
In 04, the engine speed NE is calculated from this rotation cycle f, stored in a predetermined address of the RAM 43, and the routine exits.

Next, the flow chart shown in FIG. 4 is a fuel injection amount setting routine executed every set time after the system initialization, and the fuel injection pulse width Ti as the fuel injection amount is set for each fuel injection target cylinder. To be done.

In this fuel injection amount setting routine,
In step S201, the intake air flow rate Qcy per unit rotation is calculated from the engine speed NE calculated by the cylinder discrimination / engine speed calculation routine and the intake air amount Q based on the output signal from the intake air amount sensor 21. Is calculated as the engine load (Qcy ← Q / NE), and step S202
Then, a stop flag FS for instructing the stop of the lean burn control and the stop of the high EGR control (set / cleared in a dwell extension execution / stop determination routine of FIG. 2 described later;
Refer to the value 0) for the initial value.

When FS = 0 and there is no instruction to stop the lean burn control and the high EGR control, the routine proceeds from step S202 to step S203, where the engine speed NE and the engine load, that is, step S201.
The target air-fuel ratio A / F is referred to by referring to the map in which the lean target value during lean burn control is stored for each operating region based on the intake air flow rate per unit rotation Qcy calculated in
Is set, the count value C2 for counting the elapsed time after stopping the lean burn control or the high EGR control is cleared in step S204 (C2 ← 0), and the process proceeds to step S209.

On the other hand, in the above step S202, FS = 1
If the lean burn control and the high EGR control are instructed to be stopped and the normal control is being performed, the above step S202 is performed.
To step S205, the target air-fuel ratio A / F is set to the theoretical air-fuel ratio (A / F) STO (A / F ← (A / F) STO), and then the count value C2 reaches the set value C2S in step S206. Check whether or not.

As described later, the set value C2S is the energization time (dwell) of the ignition coil 15b for each ignition of each cylinder.
Represents the waiting time until the state where there is no problem even if the dwell of the ignition coil 15b is extended again after the process of extending the ignition energy to stop the process for coil protection and returning to the normal dwell. , The coil characteristics of the ignition coil 15b, the primary current value, the surrounding environmental conditions, and the like are set in advance.

When C2 <C2S, the process proceeds from step S206 to step S207 to count up the count value C2 (C2 ← C2 + 1) and then to step S2.
The procedure proceeds to 09, and when C2 ≧ C2S, in order to restart the lean burn control or the high EGR control, the above step S206
To step S208, the stop flag FS is cleared (FS ← 0), and the process proceeds to step S209.

In step S209, the basic fuel injection amount (basic fuel injection pulse width) Tp is calculated based on the intake air flow rate Qcy per unit rotation and the target air-fuel ratio A / F (Tp ← K
× Qcy / (A / F); where K is an injector characteristic correction constant, and in step S210, the cooling water temperature by the cooling water temperature sensor 24, the throttle opening by the throttle opening sensor 22a, the idle output from the idle switch 22b, etc. Based on the cooling water temperature correction, acceleration / deceleration correction, full throttle increase correction,
Various increase amount correction coefficient C related to increase correction after idling
Set OEF.

Next, in step S211, the air-fuel ratio feedback correction coefficient λ set according to the deviation between the actual air-fuel ratio based on the output of the wide-range air-fuel ratio sensor 25 and the target air-fuel ratio.
Is read from a predetermined address of the RAM 43, step S2
At 12, the voltage correction coefficient TS for interpolating the invalid injection time of the injector 14 is set based on the battery voltage VB.

Then, the routine proceeds to step S213, where the basic fuel injection pulse width Tp is multiplied by various increasing amount correction coefficient COEF and the air-fuel ratio feedback correction coefficient λ, and then the voltage correction coefficient TS is added to correct the air-fuel ratio and the voltage. When the final fuel injection amount (fuel injection pulse width) Ti is set (Ti ← Tp × COEF × λ + TS), this fuel injection pulse width Ti is set in the injection timer of the fuel injection target cylinder in step S214. , Exit the routine.

On the other hand, FIG. 5 shows the EG executed every set time.
This is an R control routine, and it is checked in step S301 whether the EGR condition is satisfied. For this EGR condition, for example, when the throttle opening degree, the cooling water temperature, etc. satisfy the set conditions and the engine operating condition is in the region where EGR is required, it is determined that the EGR condition is satisfied.

When the EGR condition is not satisfied, the process proceeds from step S301 to step S302, and the duty ratio DUTYEGR of the drive signal for the EGR control duty solenoid valve 20 is set to 0 (DUTYEGR ← 0),
In step S306, the duty ratio DUTYEGR is set to the corresponding output port of the I / O interface 46, and the routine is exited. That is, when the EGR condition is not satisfied,
The port communicating with the control pressure passage 19 of the EGR control duty solenoid valve 20 is fully closed to introduce atmospheric pressure into the pressure chamber 18b of the EGR valve 18, and the EGR valve 18 is fully closed to close the EGR passage 17 so that the EGR passage 17 is closed. To cut.

On the other hand, when the EGR condition is satisfied in step S301, the process proceeds from step S301 to step S303 to refer to the value of the stop flag FS, and when FS = 0, the stop of the lean burn control and the high EGR control is instructed. If it is not, step S304 is executed. If FS = 1 is instructed to stop lean burn control and high EGR control, the duty of the EGR control duty solenoid valve 20 is referred to in step S305 with reference to the corresponding maps. The ratio DUTYEGR is set, the duty is set in step S306, and the routine exits.

In each of the above maps, the duty ratio of the EGR control duty solenoid valve 20 corresponding to the target EGR rate is set for each operating region specified by the engine speed NE and the basic fuel injection pulse width Tp. Cage,
The map referred to in step S304 is NOX.
The duty ratio for setting a high EGR rate (hatched area shown in step S304) in a large generation area is stored, and the map referred to in step S305 does not extend the dwell of the ignition coil 15b. The duty ratio for setting the EGR rate at which normal ignition energy can be burned is stored in.

When the lean burn control is executed by the above fuel injection amount setting routine, or when the high EGR control is executed by the above EGR control routine, the required ignition energy increases. Therefore, in the ignition control routine of FIG. The dwell of the ignition coil 15b is extended each time the ignition is performed to increase the energy accumulated on the primary side.

In this case, in order to prevent the overload of the ignition coil 15b by continuously executing the process for extending the dwell for each ignition, the dwell extension execution / stop determination routine in FIG. 2 is performed. It is configured to determine the stop, and the dwell extension execution / stop determination routine will be described below.

This dwell extension execution / cancellation determination routine is executed every set time. First, in step S401, EG
Duty ratio D of the R control duty solenoid valve 20
UTYEGR is compared with the set value DUTYS, and now high EGR
Check whether control is in progress, and DUTYEGR ≤ DUTYS,
When high EGR is not being executed, further steps
In S402, the current target air-fuel ratio A / F is compared with the set value (A / F) S to check whether lean burn control is being performed.

As a result, in the step S402, A /
When F ≦ (A / F) S and the normal stoichiometric control is currently being performed, the above steps S402 to S4 are performed.
Go to 09 to clear the count value C1 for counting the elapsed time after the dwell extension is carried out (C1 ← 0), and at step S410, clear the dwell extension flag FUP for instructing the dwell extension (FUP ← 0) Routine Exit through.

On the other hand, in step S401, the DUTY
When EGR> DUTYS and the high EGR control is in progress, or when A / F> (A / F) S in the above step S402 and lean burn control is in progress, the process proceeds from the corresponding step to step S403 and the stop flag is issued. Refer to the value of FS.

When FS = 1 and it is already instructed to stop the lean burn control and the high EGR control, the routine exits from step S409 to step S410, and when FS = 0, the above step S403 is executed. From step S404, the maximum allowable use duration setting value Tlim of the ignition coil 15b during lean burn control or high EGR control is set by table reference or calculation based on the battery voltage VB.

Maximum allowable use duration setting value Tlim
In consideration of the increase in heat generation due to the increase in the primary current of the ignition coil 15b due to the extension of the dwell, the variation in the characteristics of the ignition coil 15b, the expected surrounding environmental conditions, etc., even if ignition is repeated with the dwell extended, This corresponds to a set time that defines the maximum allowable time that can be continuously used within a range where no problem occurs in use, and as shown in step S404, the higher the battery voltage VB, the higher the maximum allowable usage. The value of the duration setting value Tlim becomes smaller.

After that, the process proceeds to step S405, and it is checked whether or not the current count value C1 representing the elapsed time after the dwell extension has reached the maximum allowable use duration setting value Tlim. If C1 <Tlim, step S406. In step S407, the dwell extension flag FUP is set (FUP ← 1) to instruct the dwell extension, the count value C1 is incremented (C1 ← C1 + 1), and the routine exits.

On the other hand, in step S405, C1 ≧ T
lim, and when the energization time of the ignition coil 15b after the dwell extension has reached the maximum allowable use duration setting value Tlim, the stop flag FS is set in step S408 (FS ← 1) and the lean burn is accompanied by the dwell extension. Coil protection is achieved by instructing to stop the control and the high EGR control, and the routine exits through steps S409 and S410 described above.

The dwell extension flag FUP is referred to in the ignition control routine of FIG. 6 executed at every ignition timing setting. When FUP = 1, the dwell of the ignition coil 15b is switched from the normal setting to the extension setting.

In this ignition control routine, step S501
Then, when the basic advance value table ADVBASE is set by referring to the basic advance value table (see the drawing) with interpolation calculation based on the engine speed NE and the basic fuel injection pulse width Tp, the knock sensor 23 from the knock sensor 23 is set in step S502. A knock correction value ADVN is set according to the presence or absence of knocking based on the signal.

In the following step S503, the above step S501
Knock correction value ADV to the basic advance value ADVBASE set in
N is added to set the control advance angle ADV (ADV ← ADVB
ASE + ADVN), the ignition timing (energization cutoff timing of the ignition coil 15b) T based on the control advance angle ADV
ADV is set in step S504. As shown in FIG.
When the time from the input of the θ1 crank pulse to the input of the θ2 crank pulse is Tθ12, and the angle between the θ1 and θ2 crank pulses (for example, 32 ° CA) is θ12,
In this embodiment, the ignition timing TADV is set based on the θ2 crank pulse (TADV ← (Tθ12 / θ12) × (θ2
-ADV)).

Next, in step S505, the battery voltage V
When the basic energization time DWLB of the ignition coil 15b is set by referring to the table with interpolation calculation based on B, step S
At 506, the rotation correction coefficient KDWLN is set by referring to the table with interpolation calculation based on the engine speed NE. The basic energization time DWLB is a basic value of the energization time based on the coil primary current that depends on the battery voltage VB. The higher the battery voltage VB, the shorter the basic energization time DWLB is stored in the table. The rotation correction coefficient KDWLN is a coefficient for correcting the influence of the non-energization time (pause time) of the coil, which becomes shorter as the engine speed NE becomes higher. The higher the engine speed NE, the smaller the value becomes. The rotation correction coefficient KDWLN of is stored in the table.

After that, the routine proceeds to step S507, refers to the value of the dwell extension flag FUP, and when FUP = 0 does not indicate the dwell extension, it proceeds to step S508 and multiplies the basic energization time DWLB by the rotation correction coefficient KDWLN. To set the energization time DWL during normal control (DWL ← DWLB × KDWL
N) On the other hand, when FUP = 1 and the dwell extension is instructed, the process proceeds from step S507 to step S509,
The energization time extension value DWLUP is set by table reference or calculation based on the battery voltage VB, and in step S510 the value obtained by adding the energization time extension value DWLUP to the basic energization time DWLB is multiplied by the rotation correction coefficient KDWLN to perform lean burn control or Set the energization time DWL during high EGR control (D
WL ← (DWLB + DWLUP) × KDWLN).

The energization time extension value DWLUP is a dwell extension amount of the ignition coil 15b for increasing ignition energy so as to prevent misfire during lean burn control and high EGR control. The higher the battery voltage VB, the higher the primary Considering that the current increases and the coil heat generation increases,
As shown in step S509, the higher the battery voltage VB, the smaller the value is set. Incidentally, step S5
In 09, the energization time extension value DW based on the battery voltage VB
Although LUP is set, the energization time extension value DWLUP may be set in consideration of parameters such as the engine speed NE in addition to the battery voltage VB.

Then, after the energization time DWL is set in the step S508 or the step S510, the process proceeds from the corresponding step to the step S511, and the time Tθ12 from the input of the θ1 crank pulse to the input of the θ2 crank pulse is reached. The energization time DWL is subtracted from the value obtained by adding the ignition timing TADV based on the θ2 crank pulse to set the energization start timing TDWL based on the θ1 crank pulse (TDWL ← Tθ12 + TADV-DWL). The ignition timing TADV is set in the ignition timing timer, the energization start timing TDWL is set in the energization start timing timer of the cylinder in step S513, and the routine exits.

As a result, the routine of FIG. 7 is started in synchronization with the θ1 crank pulse input, and in step S601, the energization start timing timer of the cylinder to be ignited is started. When the energization start timing TDWL is reached, the routine shown in FIG.
Then, the dwell of the cylinder to be ignited is set and the ignition signal for the cylinder is output from the ECU 40 to the igniter 16 (see FIG. 11), and the energization of the ignition coil 15b of the cylinder is started.

Further, the routine of FIG. 9 is started in synchronization with the θ2 crank pulse input, and in step S801, the timing of the ignition timing timer of the cylinder to be ignited is started. Then, when the ignition timing TADV is reached, the routine shown in FIG. 10 is activated by interruption, the dwell of the ignition target cylinder is cut in step S901, a high secondary voltage is induced in the ignition coil 15b, and the ignition plug of the ignition target cylinder is sparked. 15a sparks.

That is, during lean burn control and high EGR
During control, the dwell of the ignition coil 15b is extended and an ignition signal is output at an earlier timing than during normal control.
By increasing the energy stored on the primary side of the ignition coil 15b, the discharge energy from the ignition plug 15a is increased.

As a result, stable combustion can be secured even during lean burn control or high EGR control, and when the period during which the ignition energy increasing process is performed by the dwell extension reaches the set time, By stopping the dwell extension and stopping the lean burn control or the high EGR control, it is possible to prevent overload of the ignition coil 15b and prevent deterioration of controllability.

In the present embodiment, an example in which an ignition coil is provided for each cylinder and the ignition timing is controlled for each cylinder has been described. However, a type in which one ignition coil distributes power to the ignition plug of each cylinder by a distributor or It goes without saying that the present invention can also be applied to a type in which two cylinders are simultaneously ignited by one ignition coil.

[0079]

As described above, according to the first aspect of the invention, ignition is performed by extending the energization time of the ignition coil under the set operating condition, and when the set time elapses, the energization time extension is stopped. Therefore, it is possible to both increase the ignition energy by extending the energization time and protect the ignition coil. At that time, in the invention according to claim 2, the combustion control of the lean air-fuel mixture is stopped at the same time as the extension of the ignition coil energization time is stopped under the operating state by the combustion control of the lean air-fuel mixture. According to the invention, in an operating state in which a large amount of exhaust gas recirculation of a set amount or more is stopped, a large amount of exhaust gas recirculation of a set amount or more is stopped at the same time as the extension of the ignition coil energization time is stopped. It is possible to prevent the controllability from being deteriorated by stopping the extension of the energization time.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a flowchart of a dwell extension execution / cancellation determination routine.

FIG. 3 is a flowchart of a cylinder discrimination / engine speed calculation routine.

FIG. 4 is a flowchart of a fuel injection amount setting routine.

FIG. 5 is a flowchart of an EGR control routine.

FIG. 6 is a flowchart of an ignition control routine.

FIG. 7: Flow chart of θ1 crank pulse interrupt routine

FIG. 8: Flowchart of TDWL interrupt routine

FIG. 9 is a flowchart of a θ2 crank pulse interrupt routine.

FIG. 10: Flow chart of TADV interrupt routine

FIG. 11: Timing chart of ignition

FIG. 12 is a schematic configuration diagram of an engine control system.

FIG. 13 is a front view of a crank rotor and a crank angle sensor.

FIG. 14 is a front view of a cam rotor and a cam angle sensor.

FIG. 15 is a circuit configuration diagram of an electronic control system.

[Explanation of symbols]

1 ... Engine 15b ... Ignition coil 40 ... ECU (ignition setting means, energization time extending means, energization time restoring means) DWL ... Dwell (ignition coil energization time) TADV ... Ignition timing (energization cutoff timing) DWLUP ... Energization time extension value Tlim: Maximum permissible use duration set value (set time)

Claims (3)

[Claims] 1. An ignition setting means for setting an energization time and an energization interruption timing of an ignition coil based on a crank position of an engine, and an energization time extension means for extending an energization time of the ignition coil under a set operating condition. A time period after the energization time of the ignition coil is extended, and when the elapsed time is equal to or longer than a set time, an energization time returning means for stopping the extension of the energization time of the ignition coil is provided. A characteristic engine ignition control device. 2. The set operating state is an operating state based on combustion control of a lean air-fuel mixture, and the energization time returning means simultaneously stops combustion of the lean air-fuel mixture when the extension of the energization time of the ignition coil is stopped. The engine ignition control device according to claim 1, wherein the ignition control device is stopped. 3. The set operating state is an operating state in which exhaust gas recirculation of a set amount or more is performed, and the energization time returning means simultaneously stops the extension of the energization time of the ignition coil, and at the same time, sets the amount of the set amount or more 2. The engine ignition control device according to claim 1, wherein the exhaust gas recirculation of the engine is stopped.