JPS6181532A - Fuel feed controlling method of multicylinder internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent a misfire from occurring, by detecting a variation in engine speed in time of a specific stroke of each cylinder, while controlling a fuel quantity according to this variation. CONSTITUTION:A crank angle position signal (TDC signal) out of an engine speed sensor 11 is fed to a central processing unit 503 after its waveform is shaped up by a waveform shaping circuit 501. An Me counter 502 measures time ranging from the input of the last time TDC signal to that of this time TDC signal out of the Ne sensor 11. From this measured time, a variation in engine speed in time of a specific stroke of each cylinder is found. If the variation in a deceleration direction of the engine speed is less than the specified value, a fuel quantity is increased for only the cylinder. With this constitution, a misfire is from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fuel supply control method for a multi-cylinder internal combustion engine, and more particularly, to a method for controlling fuel supply for a multi-cylinder internal combustion engine, and in particular for reducing fluctuations in engine speed in the deceleration direction during a predetermined operating state such as an idling operating state of the internal combustion engine. The present invention relates to a fuel supply control method that simultaneously aims to improve exhaust gas characteristics.

(Technical Background of the Invention) During a predetermined operating state of a multi-cylinder internal combustion engine, particularly during an idling state, a particular cylinder may be prone to misfire. This is because the amount of fuel supplied to a particular cylinder is reduced compared to other cylinders due to variations in fuel supply amount characteristics due to durability deterioration between fuel injection valves arranged in each cylinder, and , due to variations in the valve clearance of the valve train installed in each cylinder, the residual gas in the aforementioned specific cylinder fluctuates compared to other cylinders, and the air-fuel mixture supplied to that cylinder becomes lean. It is thought that this is due to this.

If a specific cylinder misfires, the engine speed will fluctuate significantly, which will have a negative impact on driving performance. Therefore, in order to eliminate fluctuations in engine speed, the average value of engine speed is determined, the deviation between the actual engine speed and the average value is determined, and the amount of fuel supplied to each cylinder is determined according to the calculated deviation. A method of controlling fuel supply that increases or decreases is known, for example, from Japanese Patent Laid-Open No. 58-176424.

On the other hand, Go and HC are emitted from internal combustion engines.

In order to reduce the amount of harmful gas emissions such as NOX, an exhaust purification device such as a three-way catalyst is installed in the middle of the exhaust passage, and the air-fuel ratio of the air-fuel mixture supplied to the engine is adjusted so that the purification efficiency of the exhaust purification device is optimized. A fuel supply control method for controlling the fuel supply to a value is known.

However, in a fuel supply control method in which the amount of fuel supplied to each cylinder is increased in accordance with the above-mentioned deviation in order to reduce fluctuations in the deceleration direction of engine speed due to misfire, the air-fuel ratio of the entire engine is lower than that of the above-mentioned exhaust purification device. The purification efficiency becomes a value that deviates from the optimum value, which adversely affects the exhaust gas characteristics.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and is a multi-cylinder internal combustion engine that prevents fluctuations in the direction of deceleration of engine speed due to misfire and prevents deterioration of exhaust gas characteristics. The object of the present invention is to provide a method for controlling fuel supply to an engine.

(Structure of the Invention) In order to achieve the above object, according to the present invention, during a predetermined operating state of an internal combustion engine having a plurality of cylinders, an amount of fuel set for each cylinder is supplied to each cylinder. In the fuel supply control method, the magnitude of fluctuation in the engine speed is detected during a specific stroke of each cylinder, and when the detected magnitude of the fluctuation in the deceleration direction of the engine speed is greater than or equal to a predetermined value, the fuel supply to the cylinder is detected. Provided is a fuel supply control method for a multi-cylinder internal combustion engine, characterized in that the amount of fuel supplied to the cylinder is increased by a predetermined amount, and the amount of fuel supplied to each cylinder other than the cylinder is decreased.

(Example of the invention) An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, reference numeral 1 indicates, for example, a four-cylinder internal combustion engine, an intake pipe 2 is connected to the engine 1, and a throttle valve 3 is provided in the middle of the intake pipe 2. The throttle valve 3 is equipped with a throttle valve opening (θH) sensor 4.
is connected to the electronic control unit (hereinafter referred to as rECUJ) which converts the valve opening of the throttle valve into an electrical signal.
5.

A fuel injection valve 6 is provided in the intake pipe 2 between the engine 1 and the throttle valve 3. This fuel injection valve 6 is provided for each cylinder slightly upstream of an intake valve (not shown) in the intake space 2, and each injection valve is connected to a fuel pump (not shown) and electrically connected to the ECU 3. , the valve opening time of fuel injection is controlled by signals from the ECU 3.

On the other hand, the absolute pressure (
PaA) sensor 8 is provided, and the absolute pressure signal converted into an electrical signal by this absolute pressure sensor 8 is
Sent to CU3. Further, an intake air temperature (TA) sensor 9 is installed downstream thereof, and this intake air temperature sensor 9 also converts the intake air temperature into an electrical signal and sends it to the ECU 3.

The engine body 1 is provided with an engine water temperature (Tw) sensor 10, which is made of a thermistor or the like, and is inserted into the circumferential wall of the engine cylinder filled with cooling water, and supplies its detected water temperature signal to the ECU 3.

An engine rotation speed sensor (hereinafter referred to as "rN e sensor") 11 and a cylinder discrimination (CYL) sensor 12 are installed around the camshaft or crankshaft (not shown) of the engine, and the former 11 is installed around the 180° of the crankshaft of the engine. °
A crank angle position signal (hereinafter referred to as "rTDC signal") is generated at a predetermined crank angle position for each rotation, that is, at a crank angle position a predetermined crank angle before the top dead center (TDC) at the start of the intake stroke of each cylinder. The latter 12 outputs a cylinder discrimination signal pulse at a predetermined crank angle position of a specific cylinder, and these pulses are used as EC pulses.
Sent to U3.

A three-way catalyst 14 is disposed in the exhaust pipe 13 of the engine 1 to purify HC, GO, and NOx components in the exhaust gas. A 0□ sensor 15 is inserted into the exhaust pipe 13 on the upstream side of the three-way catalyst 14, and this sensor 15 detects the oxygen concentration in the exhaust gas and supplies the detected value signal to the ECU 3. Furthermore, E
Other engine operating parameter sensors 16, such as a sensor for detecting atmospheric pressure, are connected to the CU3.

Each time the TDC signal is input, the ECU 3 determines the engine operating state such as the 0□ feedback operating region and the idle operating region based on the various engine parameter signals described above, and also calculates the following equation ( The fuel injection time To+JT of the fuel injection valve 6 given by 1) and (2) is calculated for each injection valve.

T Out = Ti XKl + 2 ・=
(1) Here, Ti indicates the basic fuel injection time, and this basic fuel injection time Ti is calculated according to the intake pipe absolute pressure P[lA and the engine rotation speed Ne. K1 and K2 are the various sensors mentioned above, ie, the throttle valve opening sensor 4, the intake pipe absolute pressure sensor 8. Intake temperature sensor 9, engine water temperature sensor 1O-Ne sensor 11°Cylinder discrimination sensor 12.0□
Correction coefficients and correction variables that are set according to engine parameter signals from the sensor 15 and the like, and are starting characteristics and exhaust gas characteristics.

It is calculated based on a predetermined calculation formula so that various characteristics such as fuel efficiency characteristics and engine acceleration characteristics are optimized.

T 0IJT = T 0LIT + T 1AoJt
(2) The fuel injection time TOLIT determined by the above formula (1) is corrected by adding the idle rotation speed correction variable TiADJK according to the present invention. The correction variable TiAoJt has values TiAoax to T for each cylinder, respectively.
iAI)J.

, and each correction variable value is obtained by a program described later.

ECU3 calculates the fuel injection time Tot as described above.
, τ is used to supply the fuel injection valve 6 with a drive signal to open the fuel injection valve 6. FIG. 2 is a diagram showing the circuit configuration inside the ECU 3 of FIG.
The TDC signal from the Ne sensor 11 in FIG. 1 is waveform-shaped by a waveform shaping circuit 501, and then supplied to the central processing unit (hereinafter referred to as rCPUJ) 503 as an interrupt signal for executing various programs. It is also supplied to the Me counter 502.

The Me counter 502 counts the time interval from when the previous TDC signal was input from the Ne sensor 11 to when the current TDC signal was input, and the counted value Me is equal to the engine rotation speed N.
It is proportional to the reciprocal of e. Me counter 502 supplies this counted value Me to CPU 503 via data bus 510 6 Intake air temperature TA sensor 9, intake pipe absolute pressure PEA sensor 8, engine coolant temperature Tw sensor 10.02 sensor 15 in FIG.
The respective output signals from the various sensors are corrected to a predetermined voltage level by a level correction circuit 504, and then sequentially supplied to an A/D converter 506 by a multiplexer 505. The A/D converter 506 sequentially converts the output signals from the aforementioned sensors into digital signals and supplies the digital signals to the CPU 503 via the data bus 510.

The CPU 503 further connects a read-only memory (hereinafter referred to as rROMj) 507, a random access memory (ROM) 508, and a drive circuit 5 via a data bus 510.
09, the RAM 508 temporarily stores the calculation results etc. of the CPU 503, and the ROM 507
The control program executed at 503, the basic injection time Ti map of the fuel injection valve 6, etc. are stored. CPU503
In accordance with the control program stored in the ROM 507, the fuel injection time TO, JT of the fuel injection valve 6 is calculated for each cylinder according to the various engine parameter signals mentioned above.

These calculated values are sent to the drive circuit 50 via the data bus 510.
The fuel injection valves 6a to 6d of each cylinder are connected to the 6 drive circuit 509 that supplies the fuel injection valves 6a to 6d for each cylinder, and the drive circuit 509 controls the drive circuit 509 to open the fuel injection valve corresponding to the current TDC signal pulse according to the calculated value. A signal is supplied to the injection valve 6.

FIG. 3 is a timing chart illustrating the generation timing of the cylinder discrimination (CYL) signal pulse from the cylinder discrimination (CYL) sensor 12 and the TDC signal pulse from the Ne sensor 11 in FIG. 1, and corresponds to cylinder #1. A CYL signal pulse (Sa and sb) is generated at a crank angle position slightly before the TDC signal pulse (Sal and sb□) that occurs, and this CYL signal pulse causes the TDC signal pulse that occurs immediately after
It is identified which cylinder the DC signal pulse corresponds to. After the TDC signal pulse (sb,) corresponding to cylinder #1 is generated, #3, 84. $2. TDC signal pulses corresponding to each cylinder (s b2.s b3.s b4
) is repeatedly generated in sequence, and the fuel injection valves 6a to 6b of each cylinder are driven to open in synchronization with this TDC signal pulse ((C) in FIG. 3).

FIG. 4 shows a predetermined operating state 71 of the engine according to the present invention which is executed in the CPU 503 of FIG. 2 every time the TDC signal pulse is generated. 2 is a flowchart showing a fuel supply control procedure during (idling operation state).

First, in steps 1 and 2, it is determined whether the engine is in a predetermined operating state. That is, in the embodiment shown in FIG. 4, in step 1, it is determined whether the engine is in the idle operating range. This determination is made, for example, by determining that the engine is in the idle operating range when the engine rotation speed Ne is below a predetermined rotation speed NIDL (for example, 101000 rpm or less and the intake pipe absolute pressure PBA is below a predetermined value PeA+oL (for example, 360 mmHg). Also, in step 2 The valve opening θTH of the throttle valve 3 detected by the throttle valve opening (θ〒H) sensor 4 in FIG. 1 is the idle opening θII.
)L (For example, 1.5° for the total rA opening of the throttle valve
(added value) or less. Step 2
This determination is to ensure acceleration responsiveness from idling operation, and even if it is determined in step 1 that the engine is in the idling range, when it is detected that the throttle valve 3 is opened, the engine will start accelerating operation. It is determined that it is in the state.

The determination result of either step 1 or 2 is negative (No)
In this case, the program is terminated without executing the steps after step 3. If both of the determination results in steps 1 and 2 are affirmative (Yes), proceed to step 3 and determine whether the magnitude of the fluctuation in the deceleration direction of the engine speed (ΔMe) is greater than or equal to a predetermined value (ΔMeAons). . (6M e)
can be obtained as described above.

Now, assuming that the TDC signal pulse this time is Sa (Fig. 3 (b)), the pulse generation time of the previous TDC signal pulse Sb4 and the current TDC signal pulse Sa immediately after the generation of the current TDC signal pulse Sa The interval Me□n is detected by the Me counter 502 in FIG. As mentioned above, this pulse generation time interval M e in value is proportional to the reciprocal of the engine speed Ne.
The smaller the M e 1n value is, the larger the M e 1n value becomes. Then, the previous pulse (Sb, ) and current pulse (Sb, ) of the TDC signal are
The period between a□) is a specific stroke of the cylinder (#1 cylinder) corresponding to the current TDC signal pulse, for example, the period of the combustion stroke, more specifically, a predetermined crank angle before top dead center at the start of the combustion stroke. The above-mentioned time interval Me1n corresponds to the period from the moment of ignition of the air-fuel mixture that takes place at the position to the point at which the effective torque has been generated through the chemical change (combustion) of the air-fuel mixture.
is the WI (81 cylinders) that corresponds to the TDC signal pulse this time.
The combustion state of the air-fuel mixture supplied to the same cylinder when the previous TDC signal pulse (sb□) was generated is correctly reflected. Then, the memory value of the pulse generation time interval Meln-t detected when the previous TDC signal pulse (sbl) was generated for the same cylinder as the cylinder corresponding to the current TDC signal pulse (#1) is stored in the ECU. Then, the value Me 1n and the value Me,n
-1 deviation is the magnitude of the change in engine speed in the deceleration direction 6M e (= M e in - M e in -x
) is required. In this way, since the pulse generation time interval Me in value and Me 1n -L value detected when the TDC signal pulse is generated for the same cylinder are used to calculate the magnitude of the fluctuation in the deceleration direction of the engine speed ΔMe□, it is possible to prevent a misfire in the cylinder. can be detected accurately.

The deviation ΔMe can be calculated using the following formula (3) and (instead of the above method)
4) may be obtained.

B A-B Meav= Meavn-1+ , Men...
(3) ΔMe=Me n−Me av −(4)
Here, Men is the pulse generation time interval counted by the Ms counter 502 in FIG. It is an average value. A and B are constants.

For example, A is set to 256, and B is set to an appropriate value between 1 and 255.6 The deviation ΔMe obtained as described above is set to the predetermined value ΔMe.
ADJG (for example, 3.8 m5), and when the deviation ΔMe is smaller than a predetermined value ΔMeA□Q, that is, when the fluctuation in the deceleration direction of the engine speed is smaller than the predetermined value, it is determined that a misfire has not occurred in the relevant cylinder. Step 10, which will be described later
Proceed to. On the other hand, when the deviation ΔMe is larger than the predetermined value ΔMeADJG, it is determined that the cylinder (#1 cylinder) has misfired, and the process proceeds to step 4, where the idle rotation speed correction variable T i ADJK( T i ADJ
A predetermined value .DELTA.T is added to .DELTA.T) and stored in the RAM 508 in FIG. 2 as a new correction variable value. Next, each idle rotation speed correction variable T i ADJK (TiAoJz to Ti) of the cylinders (#2, 83, and #4 cylinders) other than the cylinder determined to have misfired in step 5 is determined.

, 4), the value ΔT/KIC corresponding to the value ΔT added in step 4 is subtracted, and this is stored in the RAM 508 as a new correction variable value. The value KIC is set to a value obtained by subtracting 1 from the number of cylinders (value 3 in this embodiment). In this case, the amount of fuel to be reduced in each cylinder other than the cylinder determined to be misfiring is ΔT/3, and the sum of the fuel reductions in each cylinder is equal to T to the amount of fuel to be increased in step 4 (see Figure 3). (c) T
DC signal pulse S all S az+ S ai,・
(fuel supply amount that increases or decreases immediately after each pulse occurs).

Each step from Steps 6 to 9 uses the correction variable value TiADJ.
In order to prevent the mixture from becoming over-rich or over-lean when the amount of fuel supplied to each cylinder is increased or decreased due to It is determined whether the Ti45J value is larger than the upper limit value TiLMH for each cylinder, and when the TiADJK value of any cylinder is larger than the upper limit value TiLMH, that is, if the determination result in step 6 is affirmative (Yes), the Rewrite the TiADJK value to the upper limit value TiLMH.

This value is stored in RAM 508 (step 7).

The TiADJK value of any cylinder is the lower limit T i L
When it is smaller than M L, that is, when the determination result in step 8 is affirmative (Yes), the TiAoJz value of the relevant cylinder is rewritten to the lower limit value T IL M L , and the value is stored in the RAM 508.
(Step 9).

Next, the process proceeds to step 10, in which the correction variable value (Ti
ADJ1) is read out, and the correction variable value is added to the fuel injection time T OUT obtained by the above equation (1), this is set as a new fuel injection time, and this program is ended.

As described above, the ECU 3 sends a drive signal (see Fig. 3) to open the fuel injection valve 6 of the cylinder (#1 cylinder) corresponding to the current TDC signal pulse (Sa) based on the fuel injection time TOUT obtained in step 10. c) TDC signal pulse Sa□
A fuel injection valve drive signal for the immediately following #1 cylinder is supplied to the injection valve. Then, if the deviation ΔMe is equal to or less than the predetermined value ΔMCADJG in the determination in step 3 executed immediately after the next TDC signal pulse (Sa2), the cylinder corresponding to the TDC signal pulse (Sa2) (#3 cylinder) Correction variable value T
As i ADJK (T i ADJ3), this time T
The value set in step 5 (increased by ΔT/3) executed when the DC signal pulse (Sal) is generated is maintained as it is, and the injection time TOIJT is calculated by applying this correction variable value. Then, the ECU 3 outputs the next TDC signal pulse (Sa,) based on the calculated value ToUT.
A drive signal (TDC signal pulse Sa in FIG. 3(c), fuel injector drive signal for the immediately following #3 cylinder) is supplied to the fuel injection valve 6 of the cylinder corresponding to (#3 cylinder).

(Effects of the Invention) As described above, according to the fuel supply control method for a multi-cylinder internal combustion engine of the present invention, the magnitude of fluctuation in the engine speed is detected during a specific stroke of each cylinder, and the engine speed is adjusted accordingly. When the magnitude of the detected change in the deceleration direction is greater than or equal to a predetermined value, the amount of fuel supplied to the relevant cylinder is increased by a predetermined amount, and the amount of fuel supplied to each cylinder other than the cylinder concerned is decreased, thereby preventing misfires. It is possible to prevent the engine rotational speed from changing in the direction of deceleration caused by the engine rotation, and at the same time prevent the deterioration of the exhaust gas characteristics.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a fuel supply control device for a multi-cylinder internal combustion engine to which the method of the present invention is applied;
The figure is a block diagram showing the internal configuration of the electronic control unit (EC:U) in Figure 1, and Figure 3 is a block diagram showing the internal configuration of the electronic control unit (EC:U) in Figure 1.
) signal, a TDC signal, and a timing chart for explaining how each pulse of a drive signal for a fuel injection valve of each cylinder is generated. Figure 4 shows the correction variable T1AD applied during a predetermined operating state.
It is a flowchart showing the setting procedure of JK. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 5... Electronic control unit, 6, 6a to 6b... Fuel injection valve, 11... Engine speed (N e ) sensor, 12... Cylinder discrimination (CYL) sensor, 502-Me counter, 503...
・CPU, 507...ROM, 508...RAM,
509...Drive circuit.

Claims (4)

[Claims] 1. In a fuel supply control method for supplying a predetermined amount of fuel to each cylinder during a predetermined operating state of an internal combustion engine having a plurality of cylinders, the method includes: When the magnitude of the detected change in the engine speed in the deceleration direction is greater than or equal to a predetermined value, the amount of fuel supplied to the cylinder is increased by a predetermined amount, and the amount of fuel supplied to each cylinder other than the cylinder is increased by a predetermined amount. A fuel supply control method for a multi-cylinder internal combustion engine, characterized by reducing the supply amount. 2. 2. The fuel for a multi-cylinder internal combustion engine according to claim 1, wherein the sum total of the amount of fuel to be reduced in each cylinder other than the cylinder is substantially equal to the predetermined amount to be increased in the cylinder. Supply control method. 3. Claims characterized in that the amount of fuel to be reduced in each cylinder other than the cylinder concerned is substantially equal to a value obtained by dividing the predetermined amount to increase in the cylinder concerned by a value obtained by subtracting 1 from the number of cylinders. 2. The fuel supply control method for a multi-cylinder internal combustion engine according to item 2. 4. 2. The fuel supply control method for a multi-cylinder internal combustion engine according to claim 1, wherein the predetermined operating state is an idle state.