JP3114352B2 - Air-fuel ratio 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 an air-fuel ratio control device for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, an air-fuel ratio control device for an internal combustion engine supplies an optimum amount of fuel in accordance with the amount of intake air. In this type of device, a hot-wire type air flow sensor is used to detect the amount of intake air. Used. However, when a hot-wire air flow sensor is used, there is a problem that when the intake air pulsates, a lean error occurs in the sensor output. In other words, particularly in a region where the throttle opening is substantially fully opened on the low rotation side, the pulsation propagates to the hot-wire air flow sensor on the upstream side of the intake due to the generation of the intake pulsation in the engine, causing a shift in the sensor output. Therefore, as disclosed in Japanese Patent Publication No. 59-17371, a method of detecting the magnitude of the pulsation of the sensor output and correcting the sensor output according to the magnitude is performed.

[0003]

Although the above description has been given of a correction method for a general engine, in recent years, many engines provided with an intake control device which changes the length of an intake pipe in accordance with an operating state have been developed. Can be seen. When the above-described pulsation correction method is applied to such an engine, the following problems occur. That is, as shown in FIG. 8, when the length of the intake pipe is not changed, the pulsation waveforms at the installation point of the hot-wire air flow sensor become uniform. However, when the length of the intake pipe is changed, as shown in FIG. 9, the pulsation waveform at the installation point of the hot-wire type air flow sensor becomes irregular due to the influence of the pulsation reflected wave and the like. Even when such a waveform occurs,
The same pulsation correction value was used irrespective of the operation state of the trachea length control device, and the intake air amount could not be calculated correctly.

An object of the present invention is to provide an air-fuel ratio control device for an internal combustion engine that can accurately correct the intake air amount by a hot-wire type air flow sensor and reflect it in air-fuel ratio control.

[0005]

SUMMARY OF THE INVENTION The present invention provides at least one of a variable intake pipe length control device and a variable valve timing device.
A rotation angle which is provided in an internal combustion engine having any one of the devices, and detects an engine speed of the internal combustion engine.
A sensor, disposed in an intake passage of the internal combustion engine, a hot wire type air flow rate sensor for detecting an intake air amount, the two devices
Due to the operating status of at least one of the devices
Storage means for storing a correction value in accordance with the hot-wire the magnitude of the pulsation of the air flow sensor output for each engine speed to the
The engine rotation speed detected by the rotation angle sensor and the above two devices
Based on the operating state of at least one of the devices ,
A correction unit for obtaining a correction value for the magnitude of the pulsation of the output of the hot-wire air flow sensor using the data of the storage unit, and correcting the intake air amount by the hot-wire air flow sensor using the correction value; Air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture by adjusting the fuel supply amount according to the intake air amount obtained by the correction means, and storing the air-fuel ratio in the storage means.
The corrected value is at least one of the two devices.
When one device is activated it is smaller than when it is not activated
The main point is that

[0006]

The storage means includes a variable intake pipe length control device and a variable intake pipe length control device.
At least one of the valve timing devices
A correction value corresponding to the magnitude of the pulsation of the output of the hot-wire type air flow sensor caused by the operation state of the device is stored for each engine speed . Further, the correction means is operated by using the data of the storage means.
At least one of the rotation speed and the two devices
A correction value for the magnitude of the pulsation of the sensor output is obtained based on the operating state of the device, and the correction value is used to correct the intake air amount by the hot-wire air flow sensor. Further, the air-fuel ratio control means controls the air-fuel ratio of the air-fuel mixture by adjusting the fuel supply amount according to the intake air amount obtained by the correction means. That is, the variable intake pipe length control device and the variable valve timing
Even when the operation state of at least one of the devices changes, the intake air amount is correctly calculated and reflected in the air-fuel ratio control.

[0007]

【Example】

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

FIG. 1 shows a gasoline-type multi-cylinder internal combustion engine mounted on a vehicle. An intake pipe 2 and an exhaust pipe 11 are connected to the internal combustion engine body 1. Air is drawn into the intake pipe 2 through an air cleaner 3, and the air is supplied from the intake valve 4 to the combustion chamber 5 of the internal combustion engine body 1 through the intake pipe 2. The combustion chamber 5 is defined by a cylinder head 6, a cylinder block 7, and a piston 8, and an air-fuel mixture in the combustion chamber 5 ignited by the ignition plug 9 is discharged from an exhaust valve 10 to an exhaust pipe 11.

A hot-wire type air flow sensor 12 for detecting the amount of intake air and an intake temperature sensor 1
3. Throttle valve 14, linked to the accelerator pedal,
A surge tank 15 is provided. An electromagnetic fuel injection valve 16 is attached to the intake pipe 2 near the intake port, and the electromagnetic fuel injection valve 16 operates by an electric pulse to inject fuel to the intake system. The cylinder discriminating sensor 17 and the rotation angle sensor 18 detect the crank angle from the rotation of the shaft 20 of the power distributor 19 and generate respective pulses. Ignition device 21
Includes an ignition coil, and sends a secondary ignition current to the ignition plug 9 via the distributor 19.

[0010] The water temperature sensor 22 is attached to the cylinder block 7 and detects the temperature of the cooling water. The throttle switch 23 detects that the throttle valve 14 is at an idling opening. The bypass passage 24 is connected at one end upstream of the throttle valve 14 and at the other end to the surge tank 15, and is provided to bypass the throttle valve 14. The bypass passage 24 is provided with an ISC (idle speed control) valve 25 for controlling the engine speed during idling.

Further, the intake system is provided with an intake pipe length variable control device 26. That is, the surge tank 15 is provided with a plate 27 that divides the intake passage into two, and one of the intake passages is provided with a bi-fly type on-off valve 28. A motor 29 is connected to the on-off valve 28, and the on-off valve 28 is opened and closed by the motor 29. The electronic control unit (hereinafter, referred to as ECU) 30
In the high load range where the engine speed is equal to or higher than the predetermined speed by the rotation angle sensor 18, the motor 29 is controlled to close the on-off valve 28 from the previously opened state, and one of the intake passages defined by the plate 27 is shut off. I do.

Further, the ECU 30 receives detection signals from the hot-wire type air flow sensor 12, the intake air temperature sensor 13, the cylinder discriminating sensor 17, and the water temperature sensor 22, and
6. A drive signal is output to the ignition device 21 and the ISC valve 25. Here, the output signal (analog signal) of the hot wire type air flow sensor 12 is A / D converted every 1 ms and the sensor output V
s.

The ECU 30 has a backup memory 3
1, the memory 31 retains its stored contents by power supply even when the key switch is turned off. The backup memory 31 stores a map for each engine speed as shown in FIG. In this map, the horizontal axis represents the pulsation rate PL of the output of the hot wire air flow sensor 12, and the vertical axis represents the correction value CPL. The map shows a characteristic line L1 when the intake pipe length variable control device 26 is off (opening / closing valve 28; open) and a characteristic line when the intake pipe length variable control device 26 is on (opening / closing valve 28; closed). Line L2.
This map is prepared for each engine speed, and the map shown in FIG. 2 is at 1000 rpm. here,
As shown in FIG. 3, the pulsation rate PL of the output of the hot-wire type air flow sensor 12 is within one intake pulsation (180 ° C. for four cylinders).
This is determined from the maximum output value (maximum air amount Gmax) and the minimum output value (minimum air amount Gmin) of the hot-wire air flow sensor 12 at each A).

[0014] In this embodiment, an intake passage in the intake pipe 2,
Hand compensation means E CU 30, the air-fuel ratio control means, the storage means at the backup memory 31 constitute respectively.

Next, the operation of the air-fuel ratio control device for an internal combustion engine configured as described above will be described. FIG. 4 shows a process (flow chart) executed by the ECU 30. This process
It is started every one intake pulsation (in the case of four cylinders, every 180 ° CA).

In steps 101 and 102, the ECU 30 determines the maximum air amount Gmax and the minimum air amount Gmax during that period from the output value VS of the hot-wire air flow sensor 12 for each intake pulsation (180 ° CA for four cylinders). Calculate the quantity Gmin (Fig. 3
reference). Then, in step 103, the ECU 30 calculates a pulsation rate PL from the maximum air amount Gmax and the minimum air amount Gmin using a map or the like. Further, in step 104, the ECU 30 reads the engine speed Ne.

In step 105, the ECU 30 determines whether or not the variable intake pipe length control device 26 is on. If it is off, the ECU 30 determines in step 106 the PL according to the engine speed Ne.
Using the CPL map (FIG. 2), read the correction value CPL corresponding to the pulsation rate PL based on the characteristic line L1. On the other hand, if the intake pipe length variable control device 26 is turned on in step 105, then in step 107 PL −
The correction value CPL corresponding to the pulsation rate PL based on the characteristic line L2 is read using the CPL map (FIG. 2).

After the processing of step 106 or 107, the ECU 30 proceeds to step 108 and calculates an average air amount Gav as shown in FIG. Then, in step 109, the ECU 30 calculates the intake air amount G by multiplying the average air amount Gav by the correction value CPL.

The ECU 30 calculates the valve opening time (fuel supply amount) of the fuel injection valve 16 according to the intake air amount G thus obtained, and further calculates the valve opening time (fuel supply amount) of the fuel injection valve 16. ) Is corrected by the cooling water temperature. Then, the ECU 30 controls the valve opening time of the fuel injection valve 16 to control the air-fuel ratio of the air-fuel mixture.

As described above, according to the present embodiment, the backup memory 31 is caused by the operation state of the intake pipe length variable control device 26.
To hot-wire the correction value CPL and stored for each engine rotation speed corresponding to the magnitude of the pulsation of the air flow sensor output, ECU 30 (compensation means, air-fuel ratio control means), the pulsation rate the magnitude of the pulsation of the sensor output Detected as PL. Then, the ECU 30 uses the map data in the backup memory 31 to execute the engine
A correction value CPL for the pulsation rate PL in the operating state of the variable speed and intake pipe length control device 26 is obtained, and this correction value CPL
Is used to correct the amount of intake air by the hot-wire type air flow sensor 12. Then, the ECU 30 controls the air-fuel ratio of the air-fuel mixture by adjusting the fuel supply amount by the fuel injection valve 16 according to the intake air amount. Therefore, the intake pipe length variable control device 26
Even when the operating state of the air conditioner changes, the intake air amount can be correctly calculated and reflected in the air-fuel ratio control. (Second embodiment) Next, a second embodiment will be described focusing on differences from the first embodiment.

As shown in FIG. 5, the characteristic lines are linearly approximated to the characteristic lines L1 and L2 of the pulsation correction value (CPL).
1 = a1.PL + b1, CPL2 = a2.PL + b2).
Then, the correction terms of the slopes a1 and a2 of the straight line are set as a slope correction coefficient CKPa (= a2 / a1), and the intercept b1
, B2 by the intercept correction coefficient CPLb (= b1 -b2
). As shown in FIG. 6, CKPa and CPLb are tabulated for each engine speed and stored in the backup memory 31.

As described above, the off-time correction value CPL1 of the variable intake pipe length control device 26 having a uniform pulsation waveform is corrected by the above table values CKPa and CPLb to correct the on-time correction of the variable intake pipe length control device 26. The value CPL2 is determined.

Hereinafter, a specific operation will be described with reference to FIG. In steps 201 and 202, the ECU 30 determines whether or not the hot-wire air flow sensor 12 for each intake pulsation (between 180 ° CA).
From the output value VS, the maximum air amount Gmax and the minimum air amount Gmin during that period are calculated. Then, the ECU 30
In step 203, the maximum air amount Gmax and the minimum air amount Gmin
From the pulsation rate PL. Further, in step 204, the ECU 30 reads the engine speed Ne.

In step 205, the ECU 30 determines whether or not the intake pipe length variable control device 26 is on.
In steps 206 and 207, the intercept correction coefficient CPLb = 0 and the inclination correction coefficient CKPa = 1. E
If the intake pipe length variable control device 26 is on in step 205, the CU 30 calculates the intercept correction coefficient C corresponding to the engine speed from the table in FIG.
PLb and the inclination correction coefficient CKPa are obtained.

Next, the ECU 30 determines in step 210
Variable intake pipe length control device 26 according to the engine speed at that time
The base pulsation correction value CPL1 at the time of turning off is determined. That is,
If it is 1000 rpm, it corresponds to L1 in FIG.
The base pulsation correction value CPL1 is calculated by (PL + b1).
Then, in step 211, the ECU 30 calculates the final pulsation correction value CPL by subtracting the intercept correction coefficient CPLb from the base pulsation correction value CPL1 and multiplying the value by a slope correction coefficient CKPa.

Thereafter, the ECU 30 determines in step 212 that
The average air amount Gav is calculated as shown in FIG. And
In step 213, the ECU 30 calculates the intake air amount G by multiplying the average air amount Gav by the correction value CPL.

In the above case, the case where there is only one intake control device such as a variable intake pipe length control device has been described. However, in the case of a system having a plurality of intake control devices, step 20 is adopted.
In the processing of steps 5 to 209, tables as shown in FIG. 6 may be set for the number of intake control devices. As a result, it is not necessary to prepare many maps, and the pulsation correction value can be advantageously compensated for in terms of memory capacity.

The present invention is not limited to the above-described embodiment. For example, the intake control device may be an inertial supercharger, a resonance supercharger, a variable valve timing device, or the like, in addition to the variable intake pipe length control device. It may be a turbo / supercharger device or the like.

[0029]

As described in detail above, according to the present invention,
An excellent effect of accurately correcting the intake air amount by the hot wire type air flow sensor and reflecting the corrected amount on the air-fuel ratio control is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an air-fuel ratio control device for an internal combustion engine.

FIG. 2 is a diagram showing a map for determining a correction value CPL.

FIG. 3 is a diagram showing a change in the output of a hot wire air flow sensor.

FIG. 4 is a flowchart illustrating an operation.

FIG. 5 is a diagram for explaining a second embodiment.

FIG. 6 is a diagram for explaining a second embodiment.

FIG. 7 is a flowchart for explaining the operation of the second embodiment.

FIG. 8 is a diagram showing a change in the output of a hot wire air flow sensor.

FIG. 9 is a diagram showing a change in the output of a hot-wire air flow sensor.

[Explanation of symbols]

Intake pipe length varying control device 30 compensation means as an intake pipe 12 hot wire type air flow sensor 18 rotation angle sensor 26 intake air control device as a second intake passage, the backup memory as ECU 31 storage means as an air-fuel ratio control means

Continuation of the front page (56) References JP-A-63-80037 (JP, A) JP-A-53-139938 (JP, A) JP-A-62-157245 (JP, A) JP-A-1-273856 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/18 F02D 41/34

Claims (1)

(57) [Claims] A variable intake pipe length control device and a variable valve plug
A rotation angle sensor for detecting an engine speed of the internal combustion engine , which is provided in the internal combustion engine having at least one of the imaging devices, and provided in an intake passage of the internal combustion engine, A hot-wire air flow sensor for detecting an intake air amount, and operation of at least one of the two devices
Storage means for storing, for each engine speed, a correction value corresponding to the magnitude of the pulsation of the output of the hot-wire type air flow sensor caused by the state; and the engine speed detected by the rotation angle sensor and the values of the two devices.
Based on the operating status of at least one of the devices
Correction means for obtaining a correction value for the magnitude of the pulsation of the output of the hot wire air flow sensor using the data of the storage means, and correcting the intake air amount by the hot wire air flow sensor using the correction value. the a air-fuel ratio control means for controlling the air-fuel ratio of the mixture to adjust the fuel supply amount according to the intake air amount calculated by the correction means, said stored correction value in the storage unit, the two devices Out of
When at least one of the devices is activated rather than inactive
An air-fuel ratio control device for an internal combustion engine, characterized in that: