JPH0799108B2 - Fuel injection control method for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection control method for an internal combustion engine, and more particularly, to an acceleration in an internal combustion engine equipped with a throttle actuator that drives a throttle valve based on a signal from an accelerator opening sensor. The present invention relates to a fuel injection control method for an internal combustion engine that saves torque reduction at the start.

[Prior Art] When an access pedal of an internal combustion engine (hereinafter, also referred to as an engine) is depressed and an acceleration state is achieved, a fuel injection amount required for operating the engine changes abruptly. Therefore, when the engine is in an accelerating state, the required change in the fuel injection amount cannot be dealt with only by synchronous injection, which injects the fuel injection amount calculated in synchronization with the rotation of the engine, and the air-fuel ratio is lean.
Then, there was a problem that the engine torque was reduced and smooth acceleration could not be obtained.

Therefore, conventionally, as a measure against the above problem, a fuel injection control method as described below has been used.

Conventionally, when the engine is in a steady state, for example, the basic injection amount calculated based on the throttle valve opening (hereinafter referred to as the throttle opening) or the intake air amount and the engine speed is synchronized with the engine rotation. Then, fuel injection (hereinafter referred to as synchronous injection) is performed once every two revolutions of the engine, or once every one revolution to change the throttle opening, the intake air amount, or the accelerator opening. When the acceleration of the engine is detected by
The fuel injection amount (hereinafter, referred to as asynchronous injection) is performed in a manner that the fuel injection amount corresponding to the acceleration state is not synchronized with the rotation of the engine to supplement the fuel.

Next, as described above, the fuel injection control method will be described with reference to FIG. 1 by taking as an example the simultaneous injection every revolution in which the fuel is injected into each cylinder simultaneously once per revolution of the engine.

In the figure, the horizontal axis represents the rotation angle (hereinafter referred to as crank angle) α of the crankshaft, and the vertical axis represents the throttle opening θth and the intake air amount Q. In a steady state of the engine,
Synchronous injection is performed for a time corresponding to the pulse width Pa as shown in the synchronous injection timing. Although the calculation of the pulse width is performed based on the intake air amount Q,
As shown in the figure, for example, the calculation of the pulse width Pa ₁ is performed based on the intake air amount at the calculation timing a ₁ , and the actual fuel injection timing is slightly delayed from the calculation timing. Further, since the simultaneous injection is performed every rotation, for example, in the intake process indicated by E of the second cylinder, the pulse width Pa
_The total fuel amount of ₁ and pulse width Pa ₂ is inhaled.

Next, when acceleration is detected, the fuel injection amount is calculated based on the change of the throttle opening θth at the calculation timing b which is not synchronized with the rotation of the engine, and the fuel amount having the pulse width represented by Pb is asynchronously injected.

[Problems of the Prior Art] Conventionally, the fuel injection amount is corrected and the air-fuel ratio is slightly improved by the asynchronous injection in the acceleration state as described above, but in that case, the acceleration detection delay due to the throttle opening, At the time of D and E shown in FIG. 1 immediately after the start of acceleration of the engine, the fuel injection amount cannot be corrected and the fuel injection amount cannot be corrected because the delay time such as the injection amount correction calculation delay and the intake delay due to the adhesion of the fuel pipe wall occurs Since the fuel ratio became lean, it was not possible to completely solve the torque reduction of the engine, and a shock due to the torque reduction, so-called acceleration shock, occurred, and smooth acceleration could not be obtained. Further, it has been attempted to improve the torque reduction of the engine by increasing the asynchronous injection amount, but it was impossible to fundamentally solve the delay time because only extra fuel was required.

[Object of the Invention] An object of the present invention is to provide a fuel injection control method capable of completely solving the problem of torque reduction of an engine immediately after acceleration in an engine equipped with a throttle actuator, and performing smooth acceleration. To provide.

[Structure of the Invention] As shown in FIG. 2, the present invention for achieving the above object directly calculates a throttle valve opening command value from an accelerator opening detected by an accelerator opening sensor, and opens the throttle valve opening command value. (P1) A change in the accelerator opening detected by the accelerator opening sensor in a fuel injection control method for an internal combustion engine that includes a throttle actuator that drives a throttle valve according to a degree command value and injects fuel according to the operating state. Directly detects the predetermined acceleration state of the internal combustion engine from the state, (P2) issues an asynchronous injection command at the time of detection of the predetermined acceleration state, and (P3, P4) rotates the internal combustion engine from the time of detection of the predetermined acceleration state. Fuel injection control of an internal combustion engine, characterized in that an increase in the opening of the throttle valve is restricted until a predetermined time corresponding to the number of times elapses. The law is the gist.

[Examples] Hereinafter, the present invention will be described with reference to the drawings with reference to Examples.

First, FIG. 3 is a schematic system diagram showing a four-cycle four-cylinder engine and its peripheral devices to which the method of the present invention is applied.

1 is an engine, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is an exhaust manifold 4,
An oxygen sensor for detecting the residual oxygen concentration in the exhaust gas, 6 is a fuel injection valve provided for each cylinder to inject fuel, 7 is an intake manifold, 8 is provided in the intake manifold 7, and is sent to the engine body 1. An intake air temperature sensor that detects the temperature of intake air, a water temperature sensor 9 that detects the cooling water temperature of the engine, a throttle valve 10 and a throttle position sensor 11 that detects the opening of the throttle valve 10 are provided to drive the throttle valve 10. Throttle actuator, 12 is an accelerator pedal, 13 is an accelerator opening sensor that outputs a signal according to the opening of the accelerator pedal 12 in conjunction with the accelerator pedal 12, 14 is a throttle valve 10
Is a bypass passage that is an air passage that bypasses the
An idle speed control valve (ISCV) that controls the opening area of 14 to control the idle speed, 16 is an air flow meter that measures the intake air amount, and 17 is an air cleaner that purifies the intake air.

Further, 18 is an igniter that includes an ignition coil and outputs a high voltage required for ignition, and 19 is a distributor that supplies the high voltage generated by the igniter 18 to the ignition plugs 3 of each cylinder in conjunction with a crankshaft (not shown). , 20 are installed in the distributor 19
A rotation angle sensor that outputs 24 pulse signals for one revolution of the crankshaft, that is, two revolutions of the crankshaft, 21 is a cylinder discrimination sensor that outputs one pulse signal for one revolution of the distributor 19,
22 are electronic control circuits, respectively.

Further, reference numeral 23 denotes a passage for air flowing around the throttle valve when the engine is cold, that is, a bypass passage for first idle. Reference numeral 24 denotes an air valve that controls the amount of air passing through the first idle bypass passage 23. The air valve 24 operates to open the bypass passage 23 for the first idle in order to secure the engine speed required for the warm-up operation during engine cold.

Next, FIG. 4 shows a block diagram of the electronic control circuit 22.

A central processing unit (hereinafter, simply referred to as CPU) 30 performs processing for inputting and calculating data output from each sensor according to a control program and controlling operation of various devices such as the fuel injection valve 6 and the throttle actuator 11. , 31 is a read-only memory (hereinafter simply referred to as ROM) in which data such as the control program and a map for calculating the fuel injection amount is stored, and 32 is data and arithmetic control input to the electronic control circuit 22. Random access memory (hereinafter simply referred to as RAM) where necessary data is temporarily read and written, 33 is a battery so as to retain learning value data necessary for subsequent engine operation even if the key switch is turned off. Backup Random Access Memory Backed Up (Hereafter, simply backup
(Referred to as RAM), 34 denotes an input port (not shown), a waveform shaping circuit provided as necessary, and output signals of each sensor.
The input sections are respectively provided with a multiplexer that selectively outputs to the CPU 30, an A / D converter that converts an analog signal into a digital signal, and the like. An output port 35 is provided in addition to an input port (not shown), and the fuel injection valve 6, the throttle actuator 11, etc. are provided as necessary.
An input / output unit provided with a drive circuit for driving in accordance with the control signal of the CPU30, 36 connects the respective elements such as the CPU30, ROM31 and the input unit 34 input / output unit 35, and a bus line to which each data is sent. Represents each.

Next, the control program of this embodiment will be described with reference to FIGS.
A description will be given along the flowchart shown in the figure.

FIG. 5 shows the crankshaft 2 output from the rotation angle sensor 20.
It represents a control program in which the processing is started on the basis of 24 pulse signals for rotation, that is, pulse signals at every 30 ° CA. This is the same as in the above-mentioned conventional example, in which fuel is injected simultaneously into each cylinder once per engine revolution. It represents a control program for performing simultaneous injection every revolution.

When the engine is started, this routine 100 is started,
In step 101, the counter CL is incremented, and in the following step 102, it is determined whether the counter CL is 12 or more. When it is determined that the counter CL is less than 12, the processing of the routine 100 is finished as it is, and when it is determined that the counter CL is 12 or more, the process proceeds to the subsequent step 103.

In step 103, the counter CL is set to 0, and in the following step 104, the operating state of the engine is determined based on the engine speed N obtained from the signal of the rotation angle sensor 20 and the intake air amount Q detected by the air flow meter 16. The basic injection amount τp, which is the fuel injection amount corresponding to, is calculated by the following equation.

τp = K × (Q / N) (K: coefficient) Incidentally, the coefficient K is the state of the engine, for example, the intake air temperature sensor 8
It is a correction value that is changed by changes in the temperature of the intake air detected by the sensor, the cooling water temperature detected by the water temperature sensor 9, and the like.

Next, at step 105, the basic injection amount obtained at step 104 is fuel-injected from the fuel injection valve 6, and the processing of this routine 100 is ended.

When the process of the routine 100 is executed again after the fuel injection is performed in step 105, the counter CL has already been set to zero in step 103 in the previous process, and therefore CL = 1 in step 101. Then, it is determined in step 102 that CL <12, and the processing of this routine 100 ends.

When the counter CL is incremented every 30 ° CA in step 101 and CL = 12, it is determined in step 102 that CL ≧ 12, the counter CL is set to zero in step 103, and the basic injection is performed in step 104. The amount τp is calculated, and at step 105 fuel injection of the basic injection amount τp is performed.

As described above, the processing of this routine 100 is 30 ° CA × 12 = 3
The fuel injection is performed by calculating the basic injection amount once every 60 ° CA, that is, one revolution of the engine, and represents the fuel injection control that is always performed when the engine is started.

Next, the routine 200 shown in the flowchart of FIG.
Regardless of the engine rotation, a predetermined time (for example 5 to 50ms)
The value within ec. is selected. ), And represents a control program for fuel injection control in which fuel is injected by asynchronous injection only when the engine is in an accelerated state.

Note that the processing of routine 100 and routine 200 controls the fuel injection amount from the fuel injection valve 6 by synchronous injection or asynchronous injection, and the control of the throttle actuator 11 that drives the throttle valve 10 will be described later. 7
This is performed by the processing of routine 300 shown in the flowchart of the figure.

The process of the routine 200 of FIG. 6 is started when the engine is started as in the case of the routine 100, and in step 201, the accelerator opening θacc obtained by the signal from the accelerator opening sensor 13 is read, and in step 201 At 202, it is determined whether the delay flag Fdly is 1.

The signal from the accelerator opening sensor 13 is the accelerator opening voltage Vacc, and as shown in FIG.
It is set so that, for example, when the accelerator opening θacc is zero, the accelerator opening voltage Vacc is also zero, and when the accelerator opening θacc is 100 °, the accelerator opening voltage Vacc is 5V. ing.

When it is determined in step 202 that the delay flag Fdly is 1, the processing of the routine 200 is ended, and when it is determined that the delay flag Fdly is not 1, the process proceeds to the following step 203 and proceeds to step 201. The difference between the accelerator opening .theta.acc read in and the accelerator opening .theta.acc _(i-1) read last time (5 to 50 msec before), that is, the amount of change .DELTA..theta.acc in the accelerator opening is calculated.

When the accelerator opening change amount Δθacc is calculated in step 203, the process proceeds to the following step 204, it is determined whether the accelerator opening change amount Δθacc is equal to or more than the set change amount A, and the accelerator opening change amount Δθacc is determined. Is determined to be smaller than the setting change amount A, the processing of the routine 200 is ended, and if it is determined that the accelerator opening change amount Δθacc is equal to or larger than the setting change amount A, the process proceeds to the following step 205.

In step 205, the fuel injection amount τa for performing asynchronous injection is searched from the map A based on the accelerator opening change amount Δθacc, and in the subsequent step 206, the delay flag Fdly is set to 1 and the engine speed is further increased. The delay time f ₂ (N) corresponding to the number N is searched from the map B,
It is set in the counter Cdly.

It should be noted that the map A stores data of the asynchronous injection amount τa with the accelerator opening change amount Δθacc as a parameter as shown in FIG. 9, for example, the accelerator opening change amount Δ.
Asynchronous injection amount τa when θacc is less than 1.0 °
Is zero, and when Δθacc is 3 °, τa is 5 msec.
Further, the map B stores data of the delay time f ₂ (N) using the engine speed N as a parameter as shown in FIG. 10, and the engine speed N is 1000 rpm, for example.
Delay time f ₂ when the (N) is 60 msec., And the delay time when the engine rotational speed N is 2000 rpm f ₂ (N)
Is 30 msec. This means that the delay time of the fuel intake caused by the injection amount correction calculation, the adhesion of the fuel to the pipe wall, etc. is obtained from the engine speed N. Further, in the figure, when the engine speed N increases, the delay time f ₂ (N)
The reason why is smaller is that when the engine speed is large, the interval of synchronous injection is shortened, so the acceleration response is improved, and it is not necessary to increase the delay time. The delay time is a time that the driver does not feel at all.

Next, at step 207, the asynchronous injection amount τa obtained at step 205 is injected from the fuel injection valve 6, and the processing of this routine 200 ends.

As described above, in this routine 200, it is determined in step 202 that the delay flag Fdly is not 1, and in step 204
Only when acceleration is detected based on the accelerator opening θacc at step 207, asynchronous injection is performed at step 207, and once fuel injection is performed, delay flag F is set at step 206.
dly is set to 1, and the delay flag Fd is set in routine 300 described later.
Asynchronous injection is not performed until ly is set to 0. That is, the fuel is supplemented by the asynchronous injection only when the engine is in the accelerating state and the fuel injection amount is insufficient.

The processing of the routine 300 shown in the flowchart of FIG.
Similar to the routine 200, it is performed regardless of the rotation of the engine, is processed every 1 msec., And the throttle valve 10 is controlled by controlling the throttle actuator 11.
Drive.

When the engine is started, in step 301 the throttle opening θth actually opened at that time is detected based on the signal from the throttle position sensor in the throttle actuator 11, and in step 302 the delay flag F
It is determined whether or not dly is 1, and the delay flag Fdly
If it is determined that the delay flag Fdly is 1, the process proceeds to step 306 described later, and if it is determined that the delay flag Fdly is 1, the process proceeds to the subsequent step 303.

In step 303, the counter Cdly is decremented,
Next, in step 304, it is determined whether or not the counter Cdly is zero, and if it is determined that the counter Cdly is not zero, the process proceeds to step 306 described later, and the counter Cdly
If is determined to be zero, the following step 305
At, the delay flag Fdly is set to zero.

When it is determined in step 302 that the delay flag Fdly is not 1, the counter Cdly is counted in step 304.
Is determined to be non-zero, or step 30
In step 306, which is processed when the delay flag Fdly is set to zero in step 5, the delay flag Fdl is set.
It is determined whether y is 1, and when it is determined that the delay flag Fdly is 1, the processing of this routine 300 is ended, and when it is determined that the delay flag Fdly is not 1, the next step Move to 307.

In step 307, the steps of the routine 200 described above are performed.
The basic throttle opening [theta] th ₁ searches the map C corresponding to the accelerator opening θacc detected by 201, performs control of the throttle valve 10 so as to be in the next step 308 to the basic throttle opening degree [theta] th _1, the routine Finish processing 300.

Note that the processing performed in step 308 is the throttle opening θth currently detected which is actually opened in step 301.
And the basic throttle opening θt obtained in step 307
The throttle actuator 11 drives the throttle valve 10 by the difference from h _1, and the signal detected by the throttle position sensor in the throttle actuator 11 in step 301 is the accelerator opening sensor shown in FIG. Similar to the signal of 13, the voltage Vth proportional to the throttle opening θth is detected as shown in FIG. Further, FIG. 12 shows the basic throttle opening θt with the accelerator opening θacc stored in the map C as a parameter.
h ₁ data, for example, accelerator opening θacc
When is 10 °, the basic throttle opening θth ₁ is 7 °.

Thus, in the routine 300, the accelerator opening θacc
When the delay flag Fdly is not 1, the throttle actuator 10 is controlled at step 308 only when the delay flag Fdly is 1 and the counter Cdly is 0. Throttle actuator 11 at step 308
Is being stopped. That is, the control of the throttle valve 10 is stopped until the delay flag Fdly becomes 1, the counter Cdly is decremented, and Cdly = 0.

As described above, in the present embodiment, the normal routine
By the processing of 100, the synchronous injection is performed once per one revolution of the engine, and the processing of the routine 300 in that case is step 303.
Further, the processing of step 305 is not performed, and the throttle valve 10 is changed according to the change of the accelerator rotation degree θacc. Then, if it is detected in step 204 that the engine is in an accelerating state, an asynchronous injection command is issued in step 207, and after the acceleration is detected by the processing of steps 303 to 305 of routine 300. The time is counted, and the opening of the throttle valve is maintained during the delay time f ₂ (N). And
After the delay time f ₂ (N) has elapsed, the throttle valve is driven. The processing of steps 303 to 305 is performed in order to supply the required intake air amount with a delay after the fuel injection delay time f ₂ (N) so that the air-fuel ratio does not become lean when asynchronous injection is performed. It is being done.

[Operation and Effect of Embodiment] Next, the above-mentioned embodiment will be described with reference to FIG. In the figure, the horizontal axis is the crank angle α, and the vertical axis is the throttle opening θt.
h, intake air amount Q, and accelerator opening θacc. Synchronous injection is performed for a time of a pulse width Pa calculated based on the intake air amount Q in the steady state of the engine as in FIG. 1 of the prior art. ing.

Next, when the accelerator is opened and acceleration is detected, the accelerator opening θacc is read at the timing of C, and the asynchronous injection amount τa is read in step 205 according to the accelerator opening θacc.
Is calculated, and the asynchronous injection is performed for the time of the pulse width Pc corresponding to the asynchronous injection amount τa. On the other hand, in the present embodiment, the throttle opening θth has a predetermined delay with respect to the accelerator opening θacc, and normally, for example, the accelerator opening θth.
The throttle opening θth increases from a point right below the point C in FIG. 13 with respect to the acc increasing timing.
However, the processing of steps 303 to 305 is performed by this control, and the delay time f set in step 206 is set.
₂ (N) limits the increase in the opening of the throttle valve 10, so the delay time f
_{During 2} (N), the throttle opening θth does not change. Then, the increase starts with a delay of the delay time f ₂ (N). By doing so, the asynchronous injection with the pulse width Pc coincides with the increase in the intake air amount, and the air-fuel ratio is improved.

Therefore, as compared with the example shown in FIG.
When the air-fuel ratio is lean at the time of, the value (rich) equal to or larger than the theoretical value can be set, the torque reduction of the engine can be improved, and the acceleration performance can be improved. Note in Figure 13, even when the throttle opening θth is detected accelerated in the middle increases, the throttle opening degree θth at this point in time can be predetermined delay time f ₂ (N) retention, delay time f ₂ (N) After that, the change in the opening degree starts again, so that leaning is similarly suppressed.

In this embodiment, the simultaneous rotation injection method is used. However, the fuel injection is performed once every two rotations of the engine.
The same effect can be obtained by group injection in which fuel injection is performed for each group such as single injection, first and third cylinders, second cylinder and fourth cylinder, or independent injection in which fuel injection is performed for each cylinder separately. To be

As described above in detail, according to the method of the present invention, the throttle valve opening command value is directly calculated from the accelerator opening detected by the accelerator opening sensor, and the throttle valve opening command value is used to determine the throttle opening. It drives the valve, directly detects the predetermined acceleration state of the internal combustion engine from the detected change state of the accelerator opening, issues an asynchronous injection command at the time of detection of the predetermined acceleration state, and accelerates the predetermined acceleration. The throttle actuator is controlled so that the throttle valve has a throttle opening degree corresponding to the accelerator opening degree after a predetermined time period corresponding to the number of revolutions of the internal combustion engine has elapsed since the state was detected. Therefore, according to the method of the present invention, the conventional delay time from the detection of acceleration to the fuel intake can be eliminated, the torque reduction of the engine immediately after acceleration can be improved, and smooth acceleration without acceleration shock can be obtained. Further, it is not necessary to inject extra fuel in order to reduce the acceleration shock, so that the fuel efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a timing chart for explaining the operation of the conventional fuel injection control method, FIG. 2 is an explanatory diagram showing the configuration of the present invention, and FIG. 3 is a schematic system diagram of an engine of an embodiment to which the present invention is applied. FIG. 4 is a block diagram showing the electronic control circuit, FIG. 5, FIG. 6, and FIG. 7 are flowcharts showing a control program, and FIG. 8 is an explanatory diagram showing a detection signal of an accelerator opening sensor, and FIG. The figure is step 205 in Fig. 6.
10 is an explanatory view showing a map A used in FIG. 10, FIG. 10 is an explanatory view showing a map B similarly used in step 206, FIG. 11 is an explanatory view showing a detection signal of a throttle opening sensor, and FIG. Is an explanatory view showing the map C used in step 307 of FIG. 7, and FIG. 13 is a timing chart for explaining the operation of the fuel injection control method of this embodiment. 6 ... Fuel injection valve 10 ... Throttle valve 11 ... Throttle actuator 13 ... Accelerator opening sensor 20 ... Rotation angle sensor 22 ... Electronic control circuit 30 ... CPU

Claims (1)

[Claims] 1. A throttle actuator for directly calculating a throttle valve opening command value from an accelerator opening detected by an accelerator opening sensor, and driving a throttle valve according to the throttle valve opening command value,
In a fuel injection control method for an internal combustion engine that performs fuel injection according to an operating state, a predetermined acceleration state of the internal combustion engine is directly detected from a change state of the accelerator opening detected by the accelerator opening sensor, and a predetermined acceleration state Along with issuing an asynchronous injection command at the time of detection, the increase in the opening of the throttle valve is limited from the time when the predetermined acceleration state is detected until a predetermined time corresponding to the rotation speed of the internal combustion engine elapses. Fuel injection control method for internal combustion engine.