JPS5949331A - Fuel injection quantity controller - Google Patents

Abstract

PURPOSE:To increase the engine rotation smoothly under acceleration by disabling asynchronous injection in one stroke when the accumulated injection quantity through asynchronous injection has exceeded over the upper limit of synchronous injection quantity thereby controlling the asynchronous injection quantity in each stroke optimally. CONSTITUTION:The air flow to be controlled by a throttle valve 5 is measured by an air flow meter 7 while the oxygen concentration in exhaust gas is measured by O2 sensor 8 while fuel injection is operated in a control circuit 14 such that the air-fuel ratio in each cylinder will be theoretical level to inject fuel through an injector 20 with predetermined timing. The ignition coil primary signal 13 from an ignition circuit 12 is used as an engine rotation signal or basic information in the engine control. The control circuit 14 will prevent tardy rotation of engine caused by overrich occurring when the engine transfers from low rotation to abrupt acceleration thus to achieve smooth acceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device, and more specifically to a fuel injection control device for an engine.

In conventional devices of this kind, the throttle opening is sampled at regular intervals (for example, every 20 msec), and if the difference in the throttle opening between the sampling periods is greater than a predetermined value, the opening difference is detected. Asynchronous injection was performed at the time of sampling. In this case, when the engine is rapidly accelerating from a low speed state (for example, when the slot/l/valve is fully open from an idle state), a large amount of asynchronous injection is performed, or when the engine is at low speed, the ignition interval is long. Therefore, the number of asynchronous injections between one ignition increases. At this time, fuel is injected into each cylinder at the same time, resulting in over-richness in the cylinders that have not yet been ignited.
This causes rotational sluggishness.

An object of the present invention is to provide a fuel injection control device that can smoothly increase engine speed during acceleration by optimally controlling the amount of asynchronous injection in each stroke.

The first feature of the present invention is that asynchronous injection is performed when the rate of change in throttle opening is greater than or equal to a predetermined value, and the integrated value of the injection amount due to the asynchronous injection performed during one stroke is determined by the operating state of the engine. When the upper limit value of the injection amount due to synchronous injection during one stroke is exceeded, asynchronous injection is prohibited thereafter during the one stroke.

The second feature of the present invention is that asynchronous injection is performed when the time rate of change of the throttle opening is equal to or higher than a predetermined value, and that the integrated value of the injection amount due to the asynchronous injection performed during one stroke is determined by the operating state of the engine. When an upper limit value of the injection amount due to synchronous injection during one stroke is exceeded, asynchronous injection is performed by the difference between the upper limit value and the integrated value, and thereafter, asynchronous injection is prohibited during the one stroke period. .

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

Figure 1 shows the overall configuration of the engine system, in which 1 is the engine, 2 is the air cleaner, and 3 is the engine.
1 is a throttle chamber, 4 is an inch manifold that sends air to each cylinder, 6 is an exhaust manifold that introduces exhaust gas from each cylinder into an exhaust pipe 17, and 16
is a three-way catalyst. By operating the accelerator pedal (not shown), the opening degree of the throttle valve 50 provided in the system four-way chamber 3 is controlled, thereby controlling the amount of air supplied from the share cleaner 2 to each cylinder of the engine 1. controlled. The throttle valve 5 is provided with a throttle opening sensor 15 that detects the opening iTA of the throttle valve 5, and the detection output of the throttle opening sensor 15 is input to the control circuit 14.

The amount of air controlled by the opening degree of the throttle valve 5 is measured by an air flow meter 7 provided upstream of the throttle valve 5 in the throttle chamber 3, and its detection signal is input to the control circuit 14. Note that the intake air amount can also be determined by detecting the intake pipe pressure and calculating from the detected output.

Furthermore, an 02 sensor 8 is provided near the outlet of the exhaust manifold 6 to detect the oxygen concentration in the exhaust gas.
Based on the detection signal of the 02 sensor and the air amount detection signal, the control circuit 14 calculates the fuel injection amount so that the supplied air-fuel ratio in each cylinder becomes the stoichiometric air-fuel ratio, and injects fuel into the vicinity of the inlet of each cylinder of the engine 1. (5) A control signal for injecting fuel for a predetermined period of time is output to the provided injector 20 at a predetermined timing. Further, 12 is an ignition circuit that sends an ignition signal to the ignition plug provided in each cylinder via the distributor 11, and an ignition coil return signal 13 is inputted from the ignition circuit 12 to the control circuit 14. This ignition coil return signal is processed by the control circuit 14 as an engine speed signal and is used as basic information in various engine controls including air-fuel ratio control. Distributor 11
One pulse is output to the control circuit 14 for every unit crank rotation angle (for example, 15 degrees), and the control circuit 14 counts the number of pulses and accepts a crank rotation angle interrupt at every predetermined crank rotation angle. .

Furthermore, 9 is a water temperature sensor that detects the engine cooling water temperature, and 10
is an intake temperature sensor that detects the temperature of intake air, and these detection outputs are also input to the control circuit 14 and used for fuel injection control.

Note that a description of the fuel supply system will be omitted since it is not the main point of the present invention.

Next, FIG. 2 shows the specific configuration of the control circuit 14 (6), in which 30 is a frequency dividing circuit, and the frequency dividing circuit 30 receives the ignition-next signal 13. , outputs a pulse signal with a predetermined frequency division ratio to the basic injection amount calculation circuit 40.

The basic injection amount calculation circuit 40 uses a basic injection pulse (pulse width Tp
) is outputted to the injection amount correction circuit 50 via the diode 25 and also outputted to the interrupt control section 52 in the microcomputer 60. In the injection amount correction circuit 50, the water temperature sensor 9
, takes in the detection output of the intake temperature sensor 10 and the air-fuel ratio correction signal 29 output from the microcomputer 60,
Based on these signals, the basic injection pulse (pulse width Tp
) and outputs the injector drive pulse (pulse width 7') to the base of the output transistor 24 via the OR gate 23.

A current adjustment resistor 22 and a parallel circuit of a solenoid 2OA that controls the injection valve of the injector 20 provided in each cylinder are connected in series between the collector of the output transistor 24 and the battery vn. The driving pulse (pulse width 7't) is applied to the output transistor 24.
each time the solenoid 20 of each injector 20 is applied.
An excitation current flows through A, and as a result, the opening time of the injector 2o (11 to the pulse width T of the injector drive pulse)
In other words, the fuel injection amount is controlled.

Further, the injection amount correction circuit 5o is configured so that a basic injection pulse cut signal 27 is inputted, and a fuel-rich cut is performed based on this signal 27. Further, an injection amount increase pulse 28 for increasing the fuel injection amount is input to the OR gate 23 asynchronously with the injector drive pulse under specific operating conditions of the engine (for example, during acceleration, idling, etc.).

And basic injection pulse cut signal 27 and injection t increase i
Both pulses 28 are output from a digital output port 58 within the microcomputer 60. 42 is a central processing unit (CPU) that performs digital arithmetic processing related to air-fuel ratio control; 44 is a readable and writable memory element (CRAM);
6 is a memory element (fLOM) for storing control programs such as an air-fuel ratio control program and fixed data.

Further, a timer 48 measures the startup cycle of the interrupt processing program. 52 is an interrupt control unit, which accepts various interrupts and sends them to the CP via a path line 70.
It outputs an interrupt signal to U42, takes in the basic injection pulse, and monitors the rising and falling points of the basic injection pulse.

54 is a digital input port that takes in the detection outputs of various sensors that output digital signals, and this digital input port 54 has a
, a sensor 8, a detection output of a starter switch 18 that detects the starting state of the engine, and a crank rotation angle pulse output from the distributor 11 are input.

Furthermore, 56 is an A/D converter, and the A/D converter 56 has an air flow meter 7 that outputs an analog signal.
, the detection outputs of the water temperature sensor 9 and the throttle opening sensor 15 are taken in and converted into digital signals. 58 is a digital output port that outputs a digital control signal, and the basic injection pulse cut signal 2 is output from the digital output port 58 as described above.
7 and an injection amount increase pulse 28 are output. Further, 62 is a D/A converter that outputs an analog control signal;
The D/A converter 62 outputs the air-fuel ratio correction signal 29 described above.

In this way, the input/output interface 80 composed of the digital input port 54, the digital output port 58, the A/D converter 56, and the D/A converter 62 takes in the detection outputs of various sensors and transfers them to the pass line 70.
is sent to the CPU 42 via the R
After arithmetic processing is performed based on the control program stored in the OM 46, the control signal is output from the digital output port 58 and the D/A converter 62 to the outside.

Next, FIG. 3 shows the contents of the crank rotation interrupt task. The crank rotation interrupt task is a task that is activated every predetermined crank rotation angle, for example, every 30 degrees, in accordance with the crank rotation angle pulse outputted from the distributor 11 (10). In the figure, when a task is activated in step 100, it is determined in the next step 102 whether or not the count value of a soft counter CTDC provided in the RAM 44 for counting the number of interrupts has reached 7. Here, the soft counter CTDC counts 1 for every 3 cP of crank rotation angle as shown in Figure 6, and when the count reaches 7, it counts 1.
Indicates that a stroke, for example, an inhalation stroke has ended. Step 1
If it is determined that n No. 1 in step 02, step 10
At step 6, the task is completed, and at step 102, the answer is “Ye”.
If it is determined that s, then in the next step 104, the time ΣT ass corresponding to the integrated value of the asynchronous injection amount during one stroke is determined.
y is set to O (FIG. 6, 0), and the execution of the task is ended in the next step 106.

Next, FIG. 4 shows the contents of the fuel injection control task.

The fuel injection control task is performed every certain period of time, for example, 20m5ec.
It is a task that is started every time! 11 (FIG. 6(C)). In the figure, when the task is activated in step 110, the throttle opening TA detected by the throttle opening sensor 15 is captured in the next step 112. Then, in step 114, it is determined whether the time rate of change of the throttle opening degree rA is greater than or equal to a predetermined value, that is, whether the following equation holds true.

TA-TA ol d'gt, t 7°-(1,)
In this ζ, TA is the currently captured throttle opening,
T A o ta is the throttle opening degree taken last time. If "Y e 81, l!:" is determined in step 114, the process moves to step 11.6, and in step 116, the asynchronous injection time 7'as8)' is calculated from the following equation.

T assy=99X (TA-TAold) +10
00 (usec)... (2) Then, in the next step 118, the asynchronous injection time T assy calculated in step 116 and the integrated value ΣT assy of the asynchronous injection time up to the previous time are added, and this is calculated as the integrated value of the asynchronous injection time. Let it be Σr assy.

Furthermore, in step 120, it is determined whether the integrated value ΣT a88y of the asynchronous injection time calculated in step 118 is less than or equal to the upper limit value 101 of the injection amount by synchronous injection during one stroke (intake stroke) K, which is determined depending on the operating state of the engine. If it is determined in step 120 that the time T assy (μs
Figure 6: Drive the injector 20A by e c)
F]), the execution of the task ends in step 124.

On the other hand, if it is determined in steps 114 and 120 that % N Ol, the execution of the task is terminated in step 124.

As is clear from the above, in this embodiment, the point in time when the cumulative value of the injection amount due to asynchronous injection performed during one stroke exceeds the upper limit value of the injection amount due to synchronous injection during one stroke, which is determined by the operating state of the engine. The configuration is such that asynchronous injection is prohibited thereafter during the one stroke.

Next, FIG. 5 shows another embodiment of the fuel injection control task.

Once the task is launched in step 130, step 13
In step 2, the throttle opening degree TA is captured, and in step 134, it is determined whether the time rate of change of the throttle opening degree TA is equal to or greater than a predetermined value, that is, TA(13) −TA o l d−E: 1.17°. It is determined whether or not there is.

If it is determined in step 134 that II y eS, then in step 136 the asynchronous injection time T88 is determined by the following formula.
8)' calculation is performed.

T assy=90X (TA-TAold) +10
00 (, usec) Here, TA is the current throttle opening obtained in step 132, and T A old is the throttle opening obtained last time. and step 1
In 38, the asynchronous injection time r assy data is RA
3 set in the register in M44, and further step 14
0, the asynchronous injection time T, 1l obtained in step 136
-assy and the cumulative value of the asynchronous injection time up to the previous time Σ17
'assyt-1 is added to obtain the current integrated value ΣT assy 4 of the asynchronous injection time (FIG. 6, 0). Next, in step 142, the current integrated value Σ7'assy of the non-scheduled injection time determined in step 140 is less than or equal to the upper limit value 107' of the injection amount by synchronous injection during one stroke determined by the engine operating state. If it is determined in step 142 that it is to y e8, flag A is set to (14) 0 in step 144. Here, flag A is the integrated value ΣT assy t of the current asynchronous injection time. This is a flag indicating that T has exceeded the upper limit value 107'.Furthermore, in step 146, the asynchronous injection time T set in the RAM 44 in step 138 is
The injector 20A is driven by assy (μ5ec) (see FIG. 6), and the execution of the task is ended in step 148.

On the other hand, if the determination in step 142 is NO9, the process moves to step 150, where it is determined whether flag A is O or not. Flag A is 0 in step 150
1, that is, tt yes, the flag A is set to 1 in step 152 and the upper limit value is set to 10 in step 154.
T and integrated value of asynchronous injection time up to the previous time ΣTFLB8y
The difference from i-1 is set in the RAM 44, and step 146
Then, in step 154, the injector 2OA is driven for the time D (μ5ec) set in the RAM 44, and in step 148, the execution of the task is ended.

In the embodiment shown in FIG. 4, asynchronous injection is not performed at the time tj when the integrated value ΣT a88yt of the asynchronous injection time shown in FIG. tj is the cumulative value Σ of the asynchronous injection time up to the previous time
Asynchronous injection is performed by the difference between Ta88yi-1 and the upper limit value 10T. Therefore, in the case of this embodiment, the control accuracy is higher than that of the previous embodiment.

As explained above, in the present invention, the air-fuel ratio is optimized in relation to the upper limit of the injection amount by synchronous injection during one stroke, which is determined by the engine operating state, and the asynchronous injection amount between each stroke. Therefore, according to the present invention, it is possible to prevent the engine rotation from becoming sluggish due to the air-fuel ratio becoming overrich due to the conventional asynchronous injection when the engine suddenly accelerates from a low speed state, and to prevent sudden acceleration when the engine is in a high speed state. This makes it possible to smoothly accelerate even when the vehicle is moving.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of the engine system, Fig. 2 is a block diagram showing the specific configuration of the control circuit 14, Fig. 3 is a flowchart showing the contents of the crank rotation interrupt task, and Fig. 4 is a fuel injection control task. A flowchart showing an example of
FIG. 5 is a flowchart showing another embodiment of the fuel injection control task, and FIG. 6 is a timing chart showing the relationship between synchronous injection and asynchronous injection. Agent Tatsuyuki Unuma (and 2 others) (17) Figure 3 Figure 4

Claims (2)

[Claims] (1) The detection outputs of various sensors that detect the operating state of the engine are taken in, and the fuel injection amount to each cylinder of the engine is determined from the oxygen concentration in the exhaust gas and the amount of air taken into the throttle chamber. In an engine fuel injection control device that performs multi-control by performing asynchronous injection in addition to synchronous injection to optimize the air-fuel ratio within and the cumulative value of the injection amount due to the asynchronous injection performed during one stroke exceeds the upper limit value of the injection amount due to the synchronous injection during the one stroke, which is determined by the operating state of the engine.
A fuel injection control device characterized by prohibiting asynchronous injection between strokes. (2) The detection outputs of various sensors that detect the operating state of the engine are received, and the amount of fuel injection to each cylinder of the engine is determined from the oxygen concentration in the exhaust gas and the amount of air taken into the throttle chamber. In an engine fuel injection control device that performs multi-control by performing asynchronous injection in addition to synchronous injection to optimize the air-fuel ratio within and when the cumulative value of the injection amount due to asynchronous injection performed during one stroke exceeds the upper limit value of the injection amount due to synchronous injection during one stroke, which is determined by the operating state of the engine, the upper limit value and the cumulative value are determined. A fuel injection control device characterized in that the asynchronous injection is performed by the difference in value, and thereafter the asynchronous injection is prohibited during the one stroke.