JP3489230B2 - Control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, which controls the output characteristics of the internal combustion engine by controlling fuel injection and ignition timing.

[0002]

2. Description of the Related Art Generally, in a control device for an internal combustion engine of this kind, a map having factors such as engine load and engine speed is used, and various corrections are added based on cooling water temperature information, etc. Is determined. Then, the injector (electromagnetic fuel injection valve) is driven during the energization time corresponding to this fuel injection amount, and fuel is injected and supplied from the injector to the cylinder of the internal combustion engine.

On the other hand, the injector has a minimum energization time as an individual injection characteristic that guarantees highly accurate injection performance, and that characteristic greatly affects the control accuracy of fuel injection. That is, as shown in FIG. 9, the energization time of the injector is the minimum energization time (this includes the invalid injection time).
In a longer region (region on the right side of the line A in the figure), the energization time and the fuel injection amount maintain a proportional relationship, and high control accuracy can be obtained. However, in a region where the energization time is shorter than the minimum energization time (region on the left side of the line A in the figure), variations in the fuel injection amount are caused due to variations in manufacturing of the coil and the magnetic circuit. For example, when the accelerator is returned in a high rotation range and the throttle valve is kept at a small opening (a position slightly open from the fully closed position), the intake air amount decreases, and the fuel demand amount decreases with this decrease. In this case, the energization time of the injector becomes shorter than the minimum energization time as described above, and the injection performance of the injector deteriorates.

Further, in recent years, the size of the injector has become large due to the high rotation speed and high output of the internal combustion engine, and if the metering range is made equal, the time specified as the minimum energization time in accordance with the size increase of the injector also becomes possible. growing. That is, for example, if the fuel flow rate is also increased by 30% in order to increase the engine speed by 30%, the minimum energization time becomes 1.3 times as long as before. In this case, the region where the current is equal to or shorter than the minimum energization time spreads, and the injection performance of the injector deteriorates as the energization time decreases.

Therefore, in order to solve the above problem, a device has been proposed in which fuel injection is forcibly stopped in a region where the energization time of the injector is shorter than the minimum energization time (region of energization time ≦ minimum energization time). . In addition, the engine 1
In a device that performs simultaneous injection of all cylinders once every two cycles, when energization time> minimum energization time, simultaneous injection of all cylinders is performed once per 1/2 cycle of the engine as described above, and energization time ≦ minimum energization time In this case, a device for switching the fuel injection operation so that the energization time is doubled and all cylinders are simultaneously injected once per engine cycle (Japanese Patent Publication No. 2-536).
Is proposed.

[0006]

However, in the device for forcibly stopping the fuel injection (the former device), for example, the accelerator is slightly opened during traveling on a downhill (that is, with a small opening of the throttle valve). When the vehicle is driven, the energization time changes in the vicinity of the minimum energization time. In this case, the injection stop and the return are repeated, and the pulsation of the engine output significantly deteriorates the drivability.

Further, in the device for switching the number of injections (the latter device), if the above-mentioned switching is performed when the accelerator is operated (when the throttle valve is opened), a shock sensation is generated. Therefore, it is not preferable to carry out the same processing during normal traveling, and its execution is limited only during idling.

The present invention has been made by paying attention to the above problems, and an object thereof is to provide a control device for an internal combustion engine capable of improving the drivability of the engine output without causing pulsation. To provide.

[0009]

In order to achieve the above object, the invention according to claim 1 is an electromagnetic system for injecting and supplying fuel to a cylinder of an internal combustion engine M1 as shown in FIG. Of the fuel injection valve M2 and the fuel injection amount according to the operating state of the internal combustion engine M1, and a fuel injection control means for driving the fuel injection valve M2 at an energization time corresponding to the calculated fuel injection amount. A control device for an internal combustion engine comprising M3 and an ignition timing control means M5 for calculating an ignition timing according to an operating state of the internal combustion engine M1 and controlling an ignition operation by an ignition plug M4 at the calculated ignition timing. In the above, the energization time determination means M that determines whether or not the energization time of the fuel injection valve M2 corresponding to the fuel injection amount is shorter than a predetermined minimum energization time that guarantees the operation of the fuel injection valve M2.
6, and when the energization time determination means M6 determines that the energization time of the fuel injection valve M2 at that time is shorter than the minimum energization time, the energization time is changed to the minimum energization time or a longer time. Energization time changing means M7
Similarly, when it is determined that the energization time of the fuel injection valve M2 at that time is shorter than the minimum energization time, the ignition timing changing means M8 for changing the ignition timing at that time to the retard side ,
Intake air amount for detecting the amount of air taken into the combustion engine M1
Detection means, and the ignition timing changing means M8 is a minimum
Intake air amount test for the intake air amount corresponding to energization time
Depending on the amount of decrease in intake air detected by the discharge means,
The point is to correct the fire timing to the retard side .

According to a second aspect of the invention, in the first aspect of the invention, the intake air amount detecting means is a slot.
The ignition timing changing means M8 is a throttle opening sensor which corresponds to the minimum energization time.
The throttle detected by the throttle opening sensor .
The ignition timing is corrected to the retard side according to the amount of decrease in the rottle opening .

According to a third aspect of the present invention, in the first aspect of the invention, the ignition timing changing means M8 has a delay corresponding to an intake air amount when the throttle valve is fully closed.
The angle amount is the retard amount of the most retard angle, based on the linear retard characteristic that connects the retard amount of the most retard angle and the retard amount when the intake air amount matches the minimum energization time, I am trying to correct the ignition timing.

[0012]

According to the first aspect of the invention, the fuel injection control means M3 calculates the fuel injection amount according to the operating state of the internal combustion engine M1 and the energization time corresponding to the calculated fuel injection amount. The fuel injection valve M2 is driven by. The ignition timing control means M5 calculates the ignition timing according to the operating state of the internal combustion engine M1, and controls the ignition operation by the spark plug M4 at the calculated ignition timing. That is, normally, the fuel injection control and the ignition timing control are performed according to the control command value calculated according to the engine operating state as described above.

On the other hand, the energization time determination means M6 determines whether or not the energization time of the fuel injection valve M2 corresponding to the fuel injection amount is shorter than a predetermined minimum energization time for guaranteeing the operation of the fuel injection valve M2. judge. Then, the energization time changing means M7
Is the fuel injection valve M at that time by the energization time determination means M6.
When it is determined that the second energization time is shorter than the minimum energization time, the energization time is changed to the minimum energization time or a longer time. Further, the ignition timing changing means M
Similarly, when it is determined that the energization time of the fuel injection valve M2 at that time is shorter than the minimum energization time, 8 changes the ignition timing at that time to the retard side.

In short, in the region where the energization time of the fuel injection valve M2 is shorter than the minimum energization time, the injection characteristic of the fuel injection valve M2 varies and the control accuracy deteriorates. However, according to the configuration of the present invention, the fuel injection valve Since M2 is always driven in the energization time region longer than the minimum energization time, the control accuracy does not deteriorate due to the variation in the injection characteristics of the fuel injection valve M2. Further, when the energization time is changed from the calculated value to the minimum energization time (when the calculated energization time <minimum energization time), more fuel than the originally required supply amount is injected, but the ignition timing is retarded. The output characteristic is held in the optimum state by correcting the output side. At this time, even if the energization time changes in the vicinity of the minimum energization time, the problem of pulsation of the engine output unlike the conventional case does not occur.

[0015] In addition, the ignition timing change means M8, the minimum power
The ignition timing is corrected to the retard side according to the amount of decrease in the intake air amount detected by the intake air amount detecting means with respect to the intake air amount corresponding to time. That is, in the regions to be less than the minimum conduction time, the fuel injection is continued at the minimum power supply time, the ignition timing in response to a decrease of the intake air amount is retarded. At this time, the engine output smoothly decreases. Claim
According to the invention described in 2, the ignition timing changing means M8 is
The throttle opening corresponding to the small energization time
Decrease in throttle opening detected by tor opening sensor
Correct the ignition timing to the retard side according to the amount. That is, the minimum
In the region where the energization time is shorter than the energization time, the fuel injection is
Fire continues and the throttle opening decreases.
Therefore, the ignition timing is retarded. At this time, the engine output slips
To decrease.

According to the third aspect of the present invention, the ignition timing changing means M8 sets the retard amount corresponding to the intake air amount when the throttle valve is fully closed as the maximum retard amount . based the retard amount of the outermost retarded, the linear retarded characteristic connecting the retard amount when the intake air amount matches the minimum energizing time, to correct the ignition timing. In this case, the engine output changes linearly with respect to the change in the intake air amount, and a smooth output change is obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram showing an outline of a control device of a spark ignition type multi-cylinder internal combustion engine (hereinafter referred to as an engine) in the present embodiment. In FIG.
A fuel pump 2 and a pressure regulator 3 are arranged in the fuel tank 1. The fuel (gasoline) stored in the fuel tank 1 is pumped up by the fuel pump 2, pressurized and sent to the pressure regulator 3. A delivery pipe 6 is connected to the pressure regulator 3 via a fuel filter 5, and an electromagnetic fuel injection valve (injector) 7 arranged in each cylinder in an intake pipe 10 is connected to the delivery pipe 6. Has been done.

In the pressure regulator 3, the fuel on the downstream side is adjusted to a pressure higher than the fuel pressure in the fuel tank 1 by a constant value (for example, 295 kPa), and the pressure-adjusted fuel is supplied to the fuel filter 5. After that, it is fed to the delivery pipe 6. At this time, excess fuel with respect to the adjusted pressure is returned to the fuel tank 1 through the return pipe 4. The detailed structure and operation of the pressure regulator 3 will be described later. Then, the fuel fed to the delivery pipe 6 is injected into each cylinder as the injectors 7 are opened.

On the upper plate of the fuel tank 1, a tank pressure sensor 8 for detecting a pressure difference between the atmospheric pressure and the pressure in the fuel tank 1 (relative pressure based on atmospheric pressure) is installed. The tank pressure sensor 8 may be a sensor that detects the tank pressure (absolute pressure). In this case, the differential pressure from the atmospheric pressure is detected based on the detection result of the atmospheric pressure detected by another sensor. To be done. As a method of detecting atmospheric pressure, for example, a method is known in which the pressure in the intake pipe detected when the starter is turned on is atmospheric pressure.

The engine body 10 has a piston 12 in a cylinder 11, and a combustion chamber 13 defined by a cylinder head 11a and a cylinder block 11b is formed above the piston 12. A spark plug 14 is arranged in the combustion chamber 13. The combustion chamber 13 communicates with an intake pipe 16 via an intake valve 15 and also communicates with an exhaust pipe 18 via an exhaust valve 17. Cylinder block 11b
A water temperature sensor 19 for detecting the water temperature of the cooling water is provided in the.

The intake pipe 16 is provided with an air cleaner 20 for purifying intake air and a surge tank 21 for suppressing pulsation of intake air. Surge tank 21
A throttle valve 22 that operates to open or close in conjunction with an accelerator pedal (not shown) is provided on the upstream side of the engine body 10 along with the operation of the throttle valve 22.
The amount of intake air supplied to each cylinder is controlled. The throttle valve 22 is provided with a throttle opening sensor 29 that detects the opening of the valve 22 (throttle opening). The throttle opening detected by the throttle opening sensor 29 corresponds to the intake air amount, and the sensor 29 constitutes the intake air amount detecting means in the present embodiment.

The surge tank 21 is provided with an intake pipe internal pressure sensor 25 for detecting the intake pipe internal pressure.
Further, the intake pipe 16 is provided with a bypass passage 23 that bypasses the throttle valve 22.
Idle speed control valve (hereinafter referred to as ISC valve) 2
4 are provided. The ISC valve 24 is provided in the bypass passage 2
The amount of intake air during idle operation is adjusted by opening / closing 3 to control the engine speed to a desired target speed.

Further, the exhaust pipe 18 has an oxygen concentration sensor (O ₂ sensor) 2 for detecting the oxygen concentration in the exhaust gas.
6 are provided. The rotation angle sensor 28 is attached to the distributor 27 that supplies a high voltage to the spark plug 14, and detects the engine speed and the rotation angle.

According to the above structure, the fuel injected by the injector 7 is mixed with the atmosphere sucked through the air cleaner 20, the throttle valve 22, the surge tank 21, etc., and the cylinder 11 is passed through the intake valve 15. It is supplied to the internal combustion chamber 13. Then, the air-fuel mixture supplied to the combustion chamber 13 is compressed therein, and is ignited by the ignition spark generated by the spark plug 14 to explode. The burned gas is discharged as exhaust gas to the exhaust pipe 18 via the exhaust valve 17. At this time, the oxygen concentration in the exhaust gas is measured by the O ₂ sensor 26.
Detected by.

Here, the pressure regulator 3 shown in FIG.
The configuration and operation will be described with reference to the sectional view of FIG. The pressure regulator 3 of the present embodiment adjusts the fuel pressure on the discharge side (injector 7 side) relative to the tank internal pressure, and the intake negative pressure for taking in the intake negative pressure from the intake pipe 16. The pressure introducing pipe is abolished and the return pipe 4 is shortened.

In FIG. 2, a housing 41 formed of a plurality of thin plate members has a substantially cylindrical shape, and a peripheral edge portion of a diaphragm 42 is gas-liquid tightly held in the housing 41. The diaphragm 42 divides the inside of the housing 41 into a diaphragm chamber 43 and a fuel chamber 44. A compression coil spring 45 that presses and urges the diaphragm 42 toward the fuel chamber 44 is housed in the diaphragm chamber 43. In the diaphragm chamber 43, a peripheral pressure introducing pipe 46 that introduces the tank internal pressure from the fuel tank 1. Are connected.
The peripheral pressure introducing pipe 46 is provided vertically downward at a position where the tip thereof does not penetrate the fuel, and prevents the fuel from entering the diaphragm chamber 43 even when the fuel jumps up due to vibration or the like.

In the fuel chamber 44, an inflow connection pipe 47 connected to the fuel pump 2 side pipe, an outflow connection pipe 48 connected to the injector 7 side pipe, and a return connection pipe 49 connected to the return pipe 4. Are connected. One of the return connection pipes 49 (on the left side of the drawing) extends into the fuel chamber 44,
A hollow cylindrical valve seat 50 is fixed to the tip thereof.
A valve holder 51 is attached to the center of the diaphragm 42. A rotatable ball 52 is supported by the valve holder 51, and a valve plate 53 is fixed to the ball 52. The valve plate 53 is installed so as to face the valve seat 50, and the opening area communicating with the return pipe 4 via the return connection pipe 49 changes depending on the distance between them.

The pressure regulator 3 constructed as described above operates as follows. That is, when the pressure in the fuel chamber 44 is relatively higher than the pressure in the fuel tank 1 (the pressure in the diaphragm chamber 43) (fuel pressure>
(Pressure in the tank + biasing force of the spring 45), the diaphragm 42 is displaced leftward in the drawing against the pressing force of the compression coil spring 45. At this time, the valve plate 53 and the valve seat 50 are separated (state shown in the drawing), and the fuel in the fuel chamber 44 flows into the return connection pipe 49 and is released to the fuel tank 1. as a result,
The pressure of the fuel supplied from the fuel pump 2 to the injector 7 drops.

On the other hand, the pressure in the fuel chamber 44 changes to the fuel tank 1
When the pressure is relatively lower than the internal pressure (fuel pressure <tank internal pressure + biasing force of spring 45), the diaphragm 4
2 is pushed by the compression coil spring 45, and the valve plate 53 moves to the valve seat 50.
Is displaced toward. When the valve plate 53 approaches the valve seat 50, the opening area leading to the return pipe 4 is restricted, and the fuel chamber 4
Fuel outflow from 4 is reduced. As a result, the fuel pump 2
The pressure of the fuel supplied to the injector 7 from increases. In this way, the pressure of the fuel supplied from the pressure regulator 3 to the injector 7 is kept constant with respect to the pressure in the fuel tank 1.

Further, in FIG. 1, an electronic control unit (hereinafter,
An ECU 30 is a RAM (random access memory) 31 for updating and storing information from various sensors at any time,
R that stores various control programs and control maps
An OM (read only memory (ROM) 32), a CPU (central processing unit) 33 that performs various calculations, an I / O circuit (input / output circuit) 34 that exchanges various data, and a common bus 35 that connects these are provided.

The ROM 32 stores an injection amount map for calculating the fuel injection amount (basic injection time) corresponding to the engine operating state (intake pipe pressure, engine speed) at that time. In addition, the injection amount map includes in advance, as the data acquired by the experiment, the injection amount correction related to the relative deviation between the intake pipe internal pressure and the pressure adjusted by the pressure regulator 3. That is, in the present embodiment, the fuel pressure applied to the injector 7 (adjustment pressure of the pressure regulator 3) is adjusted by the tank internal pressure, so that the relative pressure difference between the fuel pressure and the intake pipe internal pressure is always kept constant. It is not something that will be done. Therefore, the injection amount map is provided with data for correcting the relative pressure difference between the fuel pressure and the intake pipe internal pressure. Therefore, when the pressure in the intake pipe decreases, the injection amount data obtained from the injection amount map is automatically corrected in the decreasing direction. That is, the flow rate of the injector 7 is proportional to the product of the square root of the pressure difference before and after the injector (the difference between the pressure in the intake pipe and the pressure adjusted by the pressure regulator 3) and the energization time. This is compensated by reducing the injection amount (shortening the energization time of the injector 7).

Further, the CPU 33 uses the O ₂ sensor 26
The air-fuel ratio feedback and the air-fuel ratio learning control are performed according to the output result of. Further, the CPU 33 calculates the basic injection time by using the injection amount map and executes necessary injection time correction according to the output results of the various sensors described above. Further, the CPU 33 calculates an optimum ignition timing according to the output results of various sensors, and generates an ignition spark of the ignition plug 14 at the ignition timing. Others, CPU33
Drives the ISC valve 24 to perform ISC control. In addition,
In the present embodiment, the ECU 30 constitutes fuel injection control means, ignition timing control means, energization time determination means, energization time change means, and ignition timing change means.

Next, the operation of the present control device configured as described above will be described focusing on the operation of the ECU 30. FIG. 3 is a flowchart showing a calculation process of the fuel injection time (that is, the energization time of the injector 7), which is the ECU.
A predetermined cycle (for example, 2 ms) by the CPU 33 in 30
Every time).

Now, when the routine of FIG. 3 is started, C
The PU 33 first takes in the intake pipe internal pressure Pm calculated based on the output signal of the intake pipe internal pressure sensor 25 in step 101, and takes in the engine speed NE calculated based on the output signal of the rotation angle sensor 26 in subsequent step 102. Next, the CPU 33 at step 103 stores the ROM 32.
The required injection amount corresponding to the intake pipe internal pressure Pm and the engine speed NE at that time is read out as the basic injection time TP0 by using the injection amount map stored in. At this time, as described above, the correction of the fuel amount corresponding to the difference between the intake pipe internal pressure and the pressure adjusted by the pressure regulator 3 is also automatically performed.

Then, the CPU 33 fetches the tank internal pressure Pt calculated in step 104 based on the output signal of the tank internal pressure sensor 8. Further, the CPU 33 in the following step 105, the tank internal pressure correction coefficient K for correcting the change in the fuel injection amount with respect to the change in the tank internal pressure Pt.
Calculate TP. Here, the tank pressure correction coefficient KTP is
For example, it is calculated using the relationship of FIG. According to FIG.
When the tank pressure Pt is the reference pressure, KTP = 1 (no tank pressure correction). Above that, KTP> 1, and below that KTP <1.

Thereafter, in step 106, the CPU 33 calculates the water temperature correction coefficient FWL according to this cooling water temperature based on the signal from the water temperature sensor 19. Also, CP
In the next step 107, the U33 calculates the air-fuel ratio feedback coefficient FAF and the air-fuel ratio learning value FLRN for the air-fuel ratio feedback based on the signal from the O ₂ sensor 26.

Then, in step 108, the CPU 33 multiplies the basic injection time TP0 by each of the correction coefficients KTP, FWL, FAF, FLRN to calculate the fuel injection time TP by the following mathematical formula 1.
Calculated from This fuel injection time TP corresponds to the injector 7
It is the energizing time to. Note that Tv is the invalid injection time of the injector 7.

[0038]

TP = TP0 × KTP × FWL × FAF × FLRN + Tv At this time, the fuel injection time TP is calculated by using the tank pressure correction coefficient KTP, so that the fuel injection amount error due to the change in the tank pressure Pt is Will be corrected. That is, the pressure regulator 3 of the present embodiment adjusts the fuel pressure with respect to the tank internal pressure Pt.
The correction is performed according to the change of.

After that, the CPU 33 determines in step 109 whether the fuel injection time TP is longer than the minimum injection time TPmin (corresponding to the minimum energization time, which is 2 ms in this embodiment). Here, the minimum injection time TPmi
n corresponds to the minimum flow rate within the range in which the relative relationship between the energization time of the injector 7 and the fuel flow rate is guaranteed within a predetermined error rate, and is, for example, the time at which accuracy of at least ± 2% can be guaranteed. is there.

The fuel injection time TP is the minimum injection time T
Although it can be said that it is desirable to ensure the stable operation of the injector 7 when Pmin or more, the fuel injection time TP may be shorter than the minimum injection time TPmin in the following cases.

That is, first, since the pressure regulator 3 determines the adjusted pressure in accordance with the pressure difference from the tank internal pressure, for example, the above adjustment is performed in the low load region where the intake pipe internal pressure is low (= intake negative pressure is large). The pressure difference between the pressure and the intake pipe pressure increases. In this case, in order to obtain the required fuel amount, the energization time of the injector 7 is corrected to the shorter side (ROM3
2 automatic correction by map data), fuel injection time TP
May be shorter than the minimum injection time TPmin.

In addition, in a region where the accelerator is slightly opened on a downhill or the like, the flow velocity of the intake air is maintained at a constant value (for example, the speed of sound) due to the minute throttle opening. that time,
The intake air amount becomes 1 / engine speed per combustion, and the fuel injection time TP becomes shorter than the minimum injection time TPmin at high speed.

In the case described above, step 109
Is positively determined (TP <TPmin), the CPU 33 proceeds to step 110 and sets the fuel injection time TP to the above step 1
The calculated value of 08 is changed to the minimum injection time TPmin. Further, the CPU 33 sets "1" to the guard flag FG in the following step 111, and ends this processing. Here, the guard flag FG is a flag indicating that the lower limit guard of the fuel injection time TP has been executed. Then, the injector 7 is driven for injection at a predetermined timing based on the fuel injection time TP.

On the other hand, if the determination in step 109 is negative (TP ≧ TPmin), the CPU 33 determines in step 1
Proceed to 12. In this case, the CPU 33, step 112
Then, the guard flag FG is reset to "0", and this processing ends.

Next, the ignition timing calculation process will be described with reference to the flowchart of FIG. The process of FIG. 4 is C
It is executed by the PU 33 in a predetermined cycle (for example, every 2 ms).

In the process of FIG. 4, the CPU 33 first determines in step 201 whether or not the guard flag FG is in the reset state (FG = 0), and the set state (FG
= 1), the process proceeds to step 202, and if the reset state (FG = 0), the process proceeds to step 209. When the process proceeds to step 202, the CPU 33 causes the minimum injection time TP
A throttle opening for determining min (for convenience, an opening determination value VTATPL) is calculated. Here, the opening degree determination value VTATPL indicates the throttle opening degree corresponding to the minimum injection time TPmin, and is calculated by, for example, interpolating a table value having the relationship of FIG. 6 (in the figure, the opening degree determination value VTATPL
Is proportional to the engine speed NE). That is, the opening degree determination value VTATPL corresponds to the required amount of fuel at the small throttle opening degree, and increases as the engine speed NE increases.

After that, the CPU 33 determines the actual throttle opening calculated based on the output signal of the throttle opening sensor 29 in step 203 (for convenience, the detected opening value VTAi).
Is larger than the opening degree determination value VTATPL. When VTAi ≤ VTATPL (NO in step 203), the CPU 33 proceeds to step 204 and determines the opening determination value VTATL and the opening detection value V.
The difference from TAi (= VTATPL-VTAi) is calculated.

After that, the CPU 33 calculates the coefficient fk using the following equation 2 in step 205.

[0049]

[Formula 2] fk = RD / (VTATPL-VTA0) Here, RD is the retard amount in the fully closed state of the throttle,
Different values are set for each rotation speed (substantially the maximum retardation amount). VTA0 is the throttle opening when the throttle valve 22 is fully closed (for convenience, this is the opening fully closed value). It should be noted that a fixed value may be given in advance as the opening degree fully closed value VTA0, but it is also possible to set the initial value to a slightly large value and update it to the minimum value at any time by learning.

At step 206, the CPU 33 calculates the retard angle amount RCA according to the opening degree detection value VTAi at that time by using the following mathematical expression 3.

[0051]

## EQU3 ## RCA = fk.multidot. (VTATPL-VTAi) After that, the CPU 33 uses the ignition timing map (not shown) in step 207, and the basic ignition timing according to the engine speed NE and the engine load (for example, the intake pipe pressure) at that time. To calculate. Further, the CPU 33 causes the step 208.
Then, the final ignition timing is calculated by adding the retard amount RCA to the basic ignition timing. At this time, according to the equation 3, the smaller the opening detection value VTAi (actual throttle opening), the larger the retard amount RCA, and the final ignition timing largely shifts to the retard side. Then, after the calculation of the ignition timing, an ignition signal is output at a timing corresponding to the final injection timing, and the spark plug 14 generates an ignition spark.

In short, in the above process, the throttle is fully closed.
Equivalent to the throttle opening (opening fully closed value VTA0)
Delay amount RDThe most retardedDelay amountAnd the most retarded angleDelay amount
And the throttle opening that matches the minimum injection time TPmin
(Opening judgment value VTATPL)Delay amountAnd straight from
The retardation characteristic is obtained (the above-mentioned formulas 2 and 3). And that
The ignition timing is retarded according to the retardation characteristic. This and
By changing the ignition timing with a linear retard angle characteristic,
The engine output changes smoothly.

On the other hand, when step 201 becomes YES and the process proceeds to step 209 (when FG = 0), the CPU 3
3, after setting the retard angle RCA to “0” in step 209,
Go to step 207. Then, the CPU 33 performs the above ignition timing calculation in steps 207 and 208.

According to the control device of this embodiment detailed above, the following effects can be obtained. That is, when the fuel injection time TP (the energization time of the injector 7) corresponding to the required fuel injection amount becomes the minimum injection time TPmin or less (when step 109 in FIG. 3 is YES), the fuel injection time TP is the minimum. The lower limit is guarded at the injection time TPmin (step 110 in FIG. 3). Therefore, the deterioration of the control accuracy due to the variation of the injection characteristic of the injector 2 is avoided. Further, in this case, the retard amount R of the throttle fully closed
D (substantially the most retarded amount ) and the minimum injection time TPmi
The ignition timing is corrected by using a linear retarding characteristic that connects the retardation amount of the throttle opening that matches n (steps 205 to 208 in FIG. 4). As a result, the engine output changes linearly with respect to changes in the opening (corresponding to changes in the intake air amount) in the minute throttle opening range (low load range). That is, unlike the conventional device that involves the pulsation of the engine output, it is possible to obtain a smooth output change according to the intake air amount and exhibit excellent drivability.

The output from the throttle fully closed position can be easily reduced by correcting the ignition timing. (Second Embodiment) Next, a second embodiment of the present invention will be described focusing on the differences from the first embodiment. FIG. 7 is a flowchart showing the calculation process of the fuel injection time in the second embodiment. This FIG. 7 is obtained by adding steps 301 and 302 to the processing of FIG. 4 of the first embodiment,
Steps 201 to 209 in this figure are common to the flowchart in FIG.

Now, when the processing of FIG. 7 is started, the CPU
In step 301, it is determined whether or not the opening detection value VTAi (actual throttle opening) is in a predetermined idle determination range. Here, the idle determination range is VTA0 +
Within α (for example, α = 1 °). If the opening detection value VTAi is not within the idle determination range (VTAi
> VTA0 + α), the CPU 33 causes the step 2
01 to 209, and if it is in the idle judgment area (VT
If Ai ≤ VTA0 + α), proceed to step 302.

In step 302, the CPU 33 uses the map based on the relationship shown in FIG. 8 to determine the engine speed NE at that time.
Idle ignition timing corresponding to is calculated. In FIG. 8, a region on the right side of the broken line B is a region where fuel cut is performed at the time of idling, and a value on the advance side to prevent afterburn during cut delay (= processing for prohibiting fuel cut immediately after shift change). Has been selected. Further, in the region on the left side of the broken line B, the exhaust temperature at the time of idling is raised to maintain the activity of the catalyst and unburned HC (hydrocarbon)
The ignition timing on the retard side is selected in order to reduce the emission of CO2.

According to the second embodiment, when the throttle opening is very small (VTAi≤VTA0 + α) and in the idle state, the ignition timing at that time can be properly set.

The present invention can be embodied as follows in addition to the above embodiments. (1) In the above embodiment, if the fuel injection time TP (energization time of the injector 7) is shorter than the minimum injection time TPmin, the fuel injection time TP is changed to the minimum injection time TPmin, but this process may be replaced. . For example, in the above case (when TP <TPmin), the minimum injection time TPmin
Slightly longer than the predetermined time TA (for example, TA = TPmi
It may be changed to n × 1.1, or TA = TPmin + β). Also in this case, it is possible to prevent variations in the injection characteristics of the injector 7, and the accuracy of fuel injection is improved.

(2) In the above embodiment, the intake air amount detecting means is constituted by the throttle opening sensor 29, and the detection result is made to correspond to the intake air amount, but this may be changed. For example, the intake pipe 16 may be provided with a thermal air flow meter, and the intake air amount may be detected from the detection result. In this case, since the air flow rate when the throttle is fully closed differs depending on the engine speed, it is difficult to calculate the intake air amount that is the minimum injection time TPmin using the arithmetic expression.
Therefore, the retard amount RCA is assigned to the map of the engine speed and the intake air amount, and the retard amount RCA is calculated by interpolation.

(3) In the above embodiment, step 2 in FIG.
Although the ignition timing is retarded using the coefficient fk calculated in 05 and the retard amount RCA calculated in step 206, this can be changed. For example, a fixed value may be given as the retard angle amount. Also, in order to reduce the shock when changing the ignition timing, it is possible to shift to the retard side at a constant change rate with the passage of time, or to return from the retard side to the normal control at a constant change rate. May be.

(4) In the above embodiment, the pressure regulator 3 for adjusting the fuel pressure relative to the tank pressure is provided, and the fuel injection amount is corrected according to the tank pressure at any time. The control system may be constructed by changing to a pressure regulator that adjusts the fuel pressure relative to the pressure in the intake pipe.

(5) When step 109 of FIG. 3 is affirmatively determined (when TP <TPmin), that is, when the fuel injection time TP is guarded by the minimum injection time TPmin and the ignition timing is retarded. May prohibit the air-fuel ratio feedback correction and the air-fuel ratio learning.

[0064]

As described above, according to the invention described in each claim , the excellent effect that the drivability can be improved without causing the pulsation of the engine output is exhibited. Also, a smooth engine output change can be obtained.

[0065]

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a control device for an internal combustion engine in an embodiment.

FIG. 2 is a sectional view showing the configuration of a pressure regulator.

FIG. 3 is a flowchart showing a calculation process of a fuel injection time.

FIG. 4 is a flowchart showing an ignition timing calculation process.

FIG. 5 is a diagram corresponding to a calculation table of a tank pressure correction coefficient KTP.

FIG. 6 is a diagram for calculating an opening determination value VTATL.

FIG. 7 is a flowchart showing an ignition timing calculation process in the second embodiment.

FIG. 8 is a diagram showing a relationship between engine speed and idle ignition timing.

FIG. 9 is a diagram showing an injection characteristic of an injector.

FIG. 10 is a block diagram corresponding to a claim.

[Explanation of symbols]

7 ... Injector (electromagnetic fuel injection valve), 14 ... Spark plug, 30 ... Fuel injection control means, ignition timing control means, energization time determination means, energization time change means, ECU (electronic control device) as ignition timing change means , 29 ... A throttle opening sensor as an intake air amount detecting means.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F02M 51/00 F02P 5/15 A (56) References JP-A-1-237343 (JP, A) JP-A-6-249025 ( JP, A) JP 7-19084 (JP, A) JP 5-99032 (JP, A) JP 5-33711 (JP, A) JP 5-1606 (JP, A) Flat 3-95047 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02P 5/15 F02D 41/00-41/40 F02D 43/00 F02D 45/00

Claims (3)

(57) [Claims] 1. An electromagnetic fuel injection valve for injecting and supplying fuel to a cylinder of an internal combustion engine, and a fuel injection amount according to an operating state of the internal combustion engine, and the calculated fuel injection amount. And a fuel injection control means for driving the fuel injection valve at an energization time corresponding to the above, and an ignition timing according to the operating state of the internal combustion engine, and controlling an ignition operation by an ignition plug at the calculated ignition timing. In a control device for an internal combustion engine, comprising: an ignition timing control means for controlling whether or not the energization time of the fuel injection valve corresponding to the fuel injection amount is shorter than a predetermined minimum energization time that guarantees the operation of the fuel injection valve. If it is determined by the energization time determining means that determines whether or not the energization time of the fuel injection valve at that time is shorter than the minimum energization time, the energization time is set to the minimum energization time or If it is determined that the energization time changing means that changes the time to a longer time than that, and that the energization time of the fuel injection valve at that time is also shorter than the minimum energization time, ignition that changes the ignition timing to the retard side A timing changing means and an intake air amount detector for detecting the amount of air taken into the internal combustion engine.
Output means, and the ignition timing changing means corresponds to the minimum energization time.
The intake air amount is detected by the intake air amount detecting means.
The ignition timing is retarded according to the amount of decrease in the intake air amount.
A control device for an internal combustion engine, characterized in that: 2. The intake air amount detecting means is a throttle.
The opening timing sensor, and the ignition timing changing means corresponds to the minimum energization time.
The control device for an internal combustion engine according to claim 1, wherein the ignition timing is corrected to a retard side in accordance with a reduction amount of the throttle opening detected by the throttle opening sensor with respect to the throttle opening . Wherein said ignition timing changing means, the retard amount corresponding to the intake air amount when the throttle valve is fully closed and the retard amount of the most retarded, the retard amount of the outermost retard based on the linear retarded characteristic connecting the retard amount when the intake air amount matches the minimum energization time, the control apparatus for an internal combustion engine according to claim 1 for correcting the ignition timing.