JPH08144811A - Fuel supply amount controller for internal combustion engine with supercharger - Google Patents

Abstract

PURPOSE: To prevent an air flow sensor from making too large or small measurement and reduce a harmful discharged gas component by restricting either of intake amount information or fuel supply amount to a prescribed restricting range if an internal combustion engine is in a lower load operating condition than a decelerating operating condition or a prescribed load. CONSTITUTION: ECU 50, when a throttle valve 9 is fully opened and such decelerating operation as a bypass valve 42 is opened starts, computes the first clip value from theoretical frequency which is computed from the opening of an ISC11, and then the second clip value by giving tailing to an intake amount at the starting time of decelerating operation. A larger one of both the clip values is taken as an upper limit clip value, and when intake amount information obtained from the outputs of an air flow sensor 6 and a crank angular sensor 23 exceeds the upper limit clip value, a fuel injection amount is determined based on the upper limit clip value to control a fuel injection valve 3. A lower limit clip value is computed in the same way to add some restriction to the fuel injection amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine with a supercharger, and more particularly to a technique for reducing harmful exhaust gas components during deceleration and improving drivability.

[0002]

2. Description of the Related Art In recent years, in the electronically controlled fuel injection system that has become mainstream in gasoline engines, an air flow sensor is provided downstream of an air cleaner, and a crank angle sensor is attached to a crankshaft, a camshaft, etc., and measurement is performed by these sensors. The control device determines the fuel injection amount, that is, the valve opening time of the fuel injection valve from the intake flow rate and the engine rotation speed. As the type of the air flow sensor, the Karman vortex type and the hot wire type, which have smaller intake resistance than the conventional vane type, are often used. In the Karman vortex type air flow sensor, a vortex generator (triangular prism, etc.) that generates Karman vortices in the intake pipe downstream of the air cleaner.
Is arranged, and the amount of intake air is measured by detecting the number (frequency) of generated Karman vortices with an ultrasonic sensor or the like.

On the other hand, in many automobile engines, turbochargers, roots type blowers and other superchargers have been used to obtain a large output with a relatively small displacement. As is well known, a supercharger is a device that pressurizes intake air by driving a compressor using exhaust gas or crank output as a power source.By installing this supercharger in an engine, mixing into a combustion chamber is performed. The air charging efficiency is improved, and it is possible to obtain an output equivalent to that of a large displacement engine. As a supercharger mounted on an automobile engine, a turbocharger, which is relatively simple and has low drive loss and noise, is most often used.

Generally, in a turbocharged engine, when the engine speed increases, the supercharging pressure rises accordingly, which may cause knocking or blow-up. Therefore, in order to prevent such a situation, when the supercharging pressure becomes higher than a predetermined value, exhaust gas is discharged to the exhaust system without being sent to the turbine using a waste gate or the like. Also, when the driver fully closes the throttle valve during high-speed operation, supercharging does not stop instantaneously due to response delay due to inertia of the compressor, etc., but pressure is applied between the compressor and throttle valve. Inhaled air accumulates. Therefore, a bypass passage that connects the downstream side and the upstream side of the compressor is provided in parallel with the intake pipe line,
A bypass valve is provided in the bypass passage, and the bypass valve is operated by negative pressure of the manifold to circulate the pressurized intake air to the upstream side of the compressor.

[0005]

However, such a system in which the intake air is recirculated to the upstream side of the compressor through the bypass passage has a problem that the following problems occur. Normally, the intake air that has recirculated from the bypass passage to the intake conduit flows downstream and flows into the compressor, and then recirculates to the intake conduit through the bypass passage and circulates. However, depending on the layout of the intake system, the operating state of the engine, etc., the recirculated intake air may flow to the upstream side and flow back to the air flow sensor. In this case, in the Karman vortex type air flow sensor, the Karman vortex once flowing downstream together with the intake flow passes through the ultrasonic sensor again, and the intake amount is excessively or excessively measured. As a result, the fuel injection amount according to the command from the control device becomes excessive or excessive with respect to the actual intake air amount, which deteriorates drivability due to overrich or over lean and CO.
And, HC and the like are increased.

As a device for preventing the excessive measurement of the intake air amount during deceleration of the engine with a turbocharger, for example, JP-A-2-267345 and JP-A-4-191 are available.
There is one described in Japanese Patent No. 451 or the like. However, since these devices sequentially correct the measurement value of the air flow sensor according to the fluctuation of the supercharging pressure, there is a problem that the control becomes very complicated. In addition, JP-A-1-1909
Japanese Patent Publication No. 43, etc. describes a device that removes measurement noise of a Karman vortex airflow sensor due to a change in supercharging pressure via a low-pass filter. However, this device simply removes the noise appearing on the waveform of the frequency measured by the air flow sensor, and it is impossible to prevent the excessive measurement of the air flow sensor due to the backflow.

The present invention has been made in view of the above circumstances,
Providing a fuel supply control device for an internal combustion engine with a supercharger that prevents over-riching of air-fuel mixture due to excessive measurement of an air flow sensor during deceleration, thereby improving drivability and reducing harmful exhaust gas components The purpose is to do.

[0008]

Therefore, a fuel supply control device according to claim 1 of the present invention is provided in an intake system of an internal combustion engine, and supercharges the intake air by pressurizing it and supplying it to a combustion chamber of the internal combustion engine. Machine, an air flow sensor provided on the upstream side of the supercharger in the intake system and detecting intake air amount information of the internal combustion engine, and fuel supply of the internal combustion engine based on the intake air amount information detected by the air flow sensor. Fuel supply amount setting means for setting the amount, operating state detecting means for detecting the operating state of the internal combustion engine, and the internal combustion engine is in a decelerating operating state or a low load operating state lower than a predetermined load by the operating state detecting means. When it is detected that the intake air amount information and the fuel supply amount are limited to a predetermined limit range, a limiter is provided.

A fuel supply control device according to a second aspect of the present invention is the fuel supply control device according to the first aspect, further comprising a bypass passage that is provided in the intake system and connects the downstream side and the upstream side of the supercharger. A bypass valve provided in the bypass passage for opening the bypass passage during deceleration or low load operation of the internal combustion engine. Also,
A fuel supply control device according to a third aspect of the present invention is the fuel supply control device according to the first or second aspect, wherein the limiting means is an intake air detected by the air flow sensor in a stable idle state in which a detection value of the air flow sensor is stable. The limit range is set based on the quantity information.

A fuel supply control device according to a fourth aspect is the fuel supply control device according to any one of the first to third aspects, wherein the limiting means limits the intake air amount information to the predetermined range. It is characterized by being a thing. The fuel supply control device according to claim 5 is the fuel supply control device according to any one of claims 1 to 4.
In the fuel supply control device according to the item (3), a throttle means that is provided on the downstream side of the supercharger in the intake system and that adjusts the intake amount of the internal combustion engine according to an artificial operation,
An idle intake air amount adjusting means for adjusting an intake air amount when the internal combustion engine is in an idle operation state, and a setting means for setting the limit range according to an operating state of the idle intake air amount adjusting means are provided. And

A fuel supply control device according to a sixth aspect of the present invention is the fuel supply control device according to the fifth aspect, wherein the setting means calculates the theoretical intake air amount calculated from the operating state of the idle intake air amount adjusting means. It is characterized by setting based on information. A fuel supply control device according to a seventh aspect is the fuel supply control device according to the fifth aspect, wherein the limit range is equal to or more than a predetermined lower limit value and is equal to or less than a predetermined upper limit value, and the setting unit is the idle engine. A value set based on theoretical intake air amount information calculated from the operating state of the intake air amount adjusting means, and a value obtained by temporarily reducing the intake air amount information detected by the air flow sensor at the start of deceleration operation at a predetermined gradient. Is set as the upper limit value.

Further, a fuel supply control device according to an eighth aspect is the fuel supply control device according to any one of the first to seventh aspects, wherein the intake amount information or the fuel supply amount is limited by the limiting means. It is characterized in that it is released when a predetermined time has elapsed after entering the deceleration operation. Further, a fuel supply control device according to claim 9 is the fuel supply control device according to any one of claims 1 to 8, wherein the operating state detection means has a vehicle traveling speed of a predetermined value or less and the throttle. It is characterized in that deceleration or low load operation is detected when the means is equal to or less than a predetermined opening degree.

[0013]

In the fuel supply control device according to the first aspect of the present invention, when the operating state detecting means detects that the internal combustion engine is in the decelerating or low load operating state, the limiting means limits the intake air amount information or the fuel supply amount. Limit to range. As a result, even if the pressurized intake air in the intake system flows back to the air flow sensor side and the intake flow rate is measured excessively or excessively, the intake air amount information and the fuel supply amount are out of a certain limit range. As a result, the air-fuel mixture is prevented from becoming overrich or lean.

Further, in the fuel supply control device of claim 2,
For example, when the bypass valve is opened by abruptly closing the throttle means and the intake air that has recirculated from the bypass passage to the upstream side of the supercharger flows back to the air flow sensor side, the intake air amount information or the fuel supply amount is limited to some extent. The value does not fall outside the range, and overriching or over leaning of the air-fuel mixture is prevented.

Further, in the fuel supply control device of claim 3,
Since the limit range is set based on the intake amount information obtained in the stable idle state, for example, even if the intake amount information changes due to clogging of the intake system, learning will make the limit range always an appropriate value. Maintained. Further, in the fuel supply control device of the fourth aspect, when the operating state detecting means detects that the internal combustion engine is in the decelerating or low load operating state, the limiting means limits the intake air amount information to the limited range. As a result, even if the pressurized intake air in the intake system flows back to the air flow sensor side and the intake flow rate is excessively or excessively measured, the fuel supply amount calculated from the intake air amount information is out of the certain limit range. Therefore, the air-fuel mixture is prevented from becoming rich or over lean.

Further, in the fuel supply control device of claim 5,
For example, the setting means sets the upper limit value of the intake air amount information according to the valve opening amount of the idle intake air amount adjusting means. As a result, even if the intake air flow rate is excessively or excessively measured by the air flow sensor when the throttle means is fully closed, the fuel supply amount calculated from the intake air amount information does not fall outside a certain limit range, and the mixture Over-rich or over-lean is prevented.

Further, in the fuel supply control device of claim 6,
For example, the setting means, after fully closing the throttle means, after calculating the output frequency of the air flow sensor according to the valve opening amount of the idle intake air amount adjusting means based on the map,
Based on this, the upper limit value of the intake air amount information is set. Further, in the fuel supply control device according to claim 7, for example, the setting means is
While calculating the first upper limit value based on the output frequency of the air flow sensor according to the valve opening amount of the idle intake air amount adjusting means,
The second upper limit value is calculated by temporarily reducing the intake air amount information at the time of entering the deceleration operation at a predetermined gradient, and the larger one of the two upper limit values is set as the upper limit value of the intake air amount information.

Further, in the fuel supply control device of claim 8,
When the predetermined time has elapsed after entering the deceleration operation and there is no risk of excessive or undermeasurement of the air flow sensor due to the backflow of the intake air, the restriction on the intake air amount information and fuel supply amount by the restriction means is released, and Return to the fuel supply control of. Further, in the fuel supply control device according to claim 9, the vehicle speed sensor is used to detect the traveling speed of the vehicle, and the throttle sensor is used to detect the opening degree of the throttle means. The state detection means detects that the vehicle is in the deceleration or low load operation state.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an engine control system to which a fuel supply control device according to the present invention is applied. In the figure, 1 is an in-line 4-cylinder gasoline engine for automobiles (hereinafter, simply referred to as an engine), and its intake port 2 is provided with an intake manifold 4 to which a fuel injection valve 3 is attached for each cylinder. Air cleaner 5, Karman vortex type air flow sensor 6 with integrated atmospheric pressure sensor 6, intake pipe 8 with intake air temperature sensor 7, etc., throttle valve 9, throttle sensor 10 with integrated idle switch, bypass step It is connected to a throttle body 12 including a motor type ISC (idle speed controller) 11 and the like. In addition, the exhaust port 13
An exhaust pipe 17 including a three-way catalyst 16 and a muffler (not shown) is connected via an exhaust manifold 15 equipped with an O ₂ sensor 14. Further, the engine 1 has a spark plug 20 connected to an ignition coil 19 at an upper portion of the combustion chamber 18.
Is arranged. In FIG. 1, 21 is a throttle body 1.
The wax type FIAV (Fast Idle Air Valve) provided in 2 is a water temperature sensor 22 for detecting the cooling water temperature TW, and 23 is a crank angle sensor for detecting the engine speed Ne and the like.

A turbocharger 34 consisting of a turbine 32 and a compressor 33 housed in respective housings 30 and 31 is installed between the exhaust manifold 14 and the intake pipe 8. When the turbine 32 is rotated by the exhaust gas passing through the exhaust manifold 15, the compressor 33 coaxial with the turbine 32 is also rotated and the intake pipe 8
The intake air therein is compressed and sent to the combustion chamber 18. The turbine housing 30 is provided with a swing-type wastegate 35 that bypasses exhaust gas, and is opened and closed by a supercharging pressure-operated wastegate actuator 36. 37, 38 in the figure
Is an air pipe for introducing supercharged air and atmospheric air into the wastegate actuator 36, and 39 is a solenoid valve for controlling the amount of atmospheric air introduced from the air pipe 36.
Reference numeral 40 is an intercooler that cools the intake air that has become hot due to supercharging.

A bypass pipe 41 is connected to the intake pipe 8 to connect the downstream side and the upstream side of the turbocharger 34. The downstream side of the bypass pipe 41 is opened between the intercooler 40 and the throttle valve 9, and the upstream side is opened between the air flow sensor 6 and the compressor 33. A differential pressure actuated bypass valve 42 is disposed upstream of the bypass pipe 41, and opens or blocks the passage of the bypass pipe 41. The bypass valve 42 has a valve body 44, a diaphragm 45, a pressure adjusting spring 46, and the like inside a valve body 43, and an air pipe 47 communicating with the intake manifold 4 is connected to the valve body 43. The passage is opened when the pressure difference overcomes the spring force of the pressure adjusting spring 46.

On the other hand, an input / output device (not shown) and a storage device (RO
M, RAM, BURAM, etc., central processing unit (CP)
U), a timer counter, etc., and an ECU (engine control unit) 50 is installed to perform comprehensive control of the engine 1. On the input side of the ECU 50, the detection information from the above-mentioned various sensors and a vehicle speed sensor attached to a transmission (not shown) is input, and the ECU 50 determines the fuel injection amount and the ignition timing from the detection information and the control map. Etc. are calculated and the drive control of the fuel injection valve 3, the ignition coil 19, etc. is performed.

The specific procedure of the control in this embodiment will be described below with reference to the control flowcharts of FIGS. 2 to 6 and the graphs of FIGS. 7 to 12. Prior to this, the outline of the control will be briefly described. Describe. When the driver stops pressing the throttle pedal while traveling at a predetermined speed,
From that point, the vehicle shifts to deceleration operation. In this case, the throttle valve 9 is fully closed, and ISC11 and FIAV21
The intake air is supplied to the combustion chamber 18 of the engine 1 only from. On the other hand, when the throttle valve 9 is fully closed,
Although the exhaust gas amount sharply decreases, as described above, the supercharging does not stop instantaneously due to the response delay of the turbocharger 34, and the differential pressure across the throttle valve 9 increases. Then, the bypass valve 42 that has closed the bypass pipe 41 is opened, the intake air begins to flow back to the upstream side of the compressor 33, and the pressure between the compressor 33 and the throttle valve 9 gradually decreases. Therefore, 1 of engine 1
Actual intake amount per intake stroke (hereinafter, actual intake amount) A /
As indicated by the solid line in the graph of FIG. 7, Nreal decreases with a steep slope from the start of the deceleration operation.

However, at this time, if a backflow of the recirculated intake air to the airflow sensor 6 occurs, the airflow sensor 6 is oversized or undermeasured as described above.
As a result, the intake air amount calculation value (hereinafter, intake air amount information) A / N per one intake stroke of the engine 1 calculated from the output value of the air flow sensor 6 and the engine rotation speed Ne is shown in FIG.
As shown by the alternate long and short dash line in the graph, the actual intake air amount A / Nre
Occurrence of a situation where the value becomes larger or smaller than al,
The fuel injection amount is larger than the actual intake air amount, which causes a problem due to overrich. Therefore, in the present embodiment, as shown by the broken line in the graph of FIG. 7, when the intake air amount clip value A / Nclip is set and the intake air amount information A / N exceeds this value (hatched area), Alternatively, if it falls below the value, the fuel injection amount is calculated using the intake amount clip value A / Nclip. As a result, the air flow sensor 6
While performing highly accurate fuel injection control based on the output value of, it is possible to prevent a clear overshoot or undershoot due to backflow.

Further, in the normal state, the acceleration amount is increased when the charging efficiency rapidly increases, but in this embodiment, the acceleration amount is prohibited until a predetermined time elapses after the idle switch is switched from OFF to ON. Therefore, at the time of deceleration such that the throttle valve 9 is fully closed, the acceleration amount is not increased even if the intake air is excessively or insufficiently measured due to the backflow of the airflow sensor 6, so that the air-fuel mixture is overriched. Is also prevented.

Now, the driver turns on the ignition key.
Then, when the engine 1 is started, the ECU 50 causes the ECU 50 to perform a predetermined control interval TCI (for example, 10 ms) as shown in FIG.
The fuel injection control main routine shown in the flowchart is repeatedly executed. When this main routine is started, the ECU 50 first reads the operation information from the various sensors described above into the RAM in step S1, and then, in step S3, the intake air amount information based on the output values of the air flow sensor 6 and the crank angle sensor 23. Calculate A / N. next,
The ECU 50 determines in step S5 whether or not the deceleration operation is being performed, and if the determination is No (negative), the step S5 is performed.
In step 6, the value of the first countdown timer TCD1 is set to the predetermined time T
After resetting to S1 (1 second in this embodiment), the routine proceeds to step S13 in FIG. 3 and fuel injection is performed based on the intake air amount information A / N calculated in step S3. The deceleration operation is performed under the following various conditions: the idle switch is ON, the volumetric efficiency EV is a predetermined value (20% in this embodiment) or more, and the vehicle speed V is a predetermined value (in this embodiment). , 90km
/ H) or less, when the engine is stalled or not, and when the output value of the water temperature sensor 22 is normal, the answer is Yes.

When all the above-mentioned conditions are satisfied and the determination in step S5 becomes Yes, the ECU 50 causes the step S5 to proceed.
At 7, it is determined whether or not the value of the first countdown timer TCD1 is 0. If this determination is Yes, the process proceeds to step S13. Immediately after the start of the deceleration operation, the determination in step S7 is naturally No, and therefore the ECU 50 determines in step S8.
After subtracting the value of the control interval TCI from the first countdown timer TCD1, the process proceeds to step S9 of FIG. 3 to execute the A / Nclip calculation subroutine of FIG. 4 to calculate the intake amount clip value A / Nclip.

When this subroutine is started, the ECU 5
0 is the first ISC1 at step S21.
The ISC frequency FISC determined by the opening of 1 is searched from the map of FIG. The ISC frequency FISC is the output frequency of the air flow sensor 6 according to the amount of intake air passing through the ISC 11, and as indicated by the broken line in the map of FIG.
It increases according to the opening degree of 11 (the number of steps). Then E
In step S23, the CU 50 searches the map of FIG. 9 for the FIAV frequency FFIAV determined by the current output value of the water temperature sensor 22. FIAV frequency FFIAV is F
It is the output frequency of the air flow sensor 6 according to the amount of intake air passing through the IAV 21, decreases as the water temperature WT rises, and becomes 0 when the warm-up ends.

ISC frequency FISC and FIAV frequency FFI
When the search with the AV is completed, the ECU 50 determines in step S25.
Then, the theoretical frequency Flog at the present time is calculated by the following formula.
In the map of FIG. 8, the theoretical frequency Flog is shown by the alternate long and short dash line. Flog = FISC + FFIAV + ΔFlog where ΔFlog is the fully closed frequency correction value, and is calculated by the ΔFlog learning subroutine described later.

After calculating the theoretical frequency Flog, the ECU 5
0 is the upper limit clip frequency FHclip and the lower limit clip frequency FLclip according to the following equation in step S27,
The first upper limit clip value A / NHclip 1 and the lower limit clip value A / NLclip are calculated. FHclip = (FISC + ΔFlog) · KCH + FFIAV FLclip = (FISC + ΔFlog) · KCL + FFIAV A / NHclip 1 = FHclip / Ne A / NLclip = FLclip / Ne Here, KCH and KCL are the upper and lower limits, and the upper and lower limits are KCH and KCL. Then, in order to prevent misfire due to overrich, the upper limit clip correction coefficient KCH is about 1.2,
The lower limit clip correction coefficient KCL is set to a value of about 0.8. In the map of FIG. 8, the upper and lower clip frequencies FHclip and FLclip are indicated by solid lines.

When the calculation of the first upper limit clip value A / NHclip 1 and the lower limit clip value A / NLclip is completed, the ECU
In step S29, 50 calculates the second upper limit clip value A / NHclip 2 by the following formula. A / NHclip 2 = A / NDC-ΔA / Ntail · n where A / NDC is the intake air amount when entering the deceleration state, ΔA / N
tail is a predetermined tailing constant, n is the number of times of control, and as shown in FIG. 10, the second upper limit clip value A / NHclip
2 decreases by ΔA / Ntail each time the control is repeated.

First upper limit clip value A / NHclip 1 and second
When the calculation with the upper limit clip value A / NHclip 2 is completed, E
In step S31, the CU 50 uses the larger value of the two as the upper limit clip value A / NHclip. A / NHclip = max [A / NHclip 1, A / NHclip 2] As a result, the upper limit clip value A / NHclip is gradually reduced with a predetermined gradient from the start of the deceleration state, as shown by the solid line in the graph of FIG. After that, it will converge to a certain value.
The alternate long and short dash line in FIG. 11 indicates the first upper limit clip value A / NHc.
Lip 1 is shown, the broken line shows the lower limit clip value A / NLclip, and the chain double-dashed line shows the second upper limit clip value A / NHclip 2.

Upper limit clip value A / NHclip and lower limit clip value A / NLclip in the A / Nclip calculation subroutine
When the calculation of the
Then, it is determined whether or not the intake air amount information A / N obtained from the detection result of the air flow sensor 6 is between the upper limit clip value A / NHclip and the lower limit clip value A / NLclip. If this determination is Yes, then step S13 is performed as it is.
If No, the process proceeds to step S11. If it is larger than the upper limit clip value A / NHclip, the upper limit clip value A / NHclip is changed to the lower limit clip value A / NLc.
Lower limit clip value A / NLclip if smaller than lip
Are respectively substituted into the intake air amount information A / N. When the value of the first countdown timer TCD1 becomes 0 during the control and the determination in step S7 becomes Yes, the ECU 50 stops the intake amount clipping and proceeds to step S13. This is because when the predetermined time TS1 elapses after the entry of the deceleration operation, the excessive measurement of the airflow sensor 6 due to the backflow can be ignored in terms of time. The ECU 50 thus performs the intake air amount information A
When / N is obtained, the ECU 50 proceeds to step S13, as shown in FIG.
The TINJ calculation subroutine shown in the flowchart of FIG. 12 and the time chart of FIG. 12 is executed.

Now, when the TINJ calculation subroutine is started, the ECU 50 firstly executes the engine 1
The cooling water temperature TW is a predetermined value TWA (20 ° C. in this embodiment)
Determine if it is higher. If the determination is No, the process proceeds to step S55, which will be described later, and the acceleration amount is permitted to calculate the fuel injection time TINJ. This is because there is no possibility that the recirculated intake air will flow back to the air flow sensor 6 because the opening degree of the ISC 11 and the FIAV 21 is large in the cold state.

When the cooling water temperature TW rises and the determination in step S41 becomes Yes, the ECU 50 subtracts the value of the control interval TCI from the second countdown timer TCD2 described later in step S43. The second countdown timer TCD2 is set so that the value at the time of starting the engine is 0 and does not become 0 or less. Next, the ECU 50 determines in step S45 whether the idle switch is ON, that is, whether the throttle valve 9 is fully closed. If the determination is No, the process proceeds to step S55 described below, but Yes
If so, the ECU 50 determines in step S47 whether the idle switch is switched from OFF to ON. Note that this determination is Yes when the previous value of the output of the idle switch is OFF and the current value is ON.

When the driver stops depressing the accelerator pedal and the idle switch is switched from OFF to ON (points a, b and c in FIG. 12), the determination in step S47 is Yes and the ECU 50 Is step S
After the value of the second countdown timer TCD2 is reset to a predetermined time TS2 (4 seconds in this embodiment) at 49, the fuel injection amount (fuel injection time) TIN is calculated by the following equation at step S51.
Calculate J. In the following equation, C is a conversion constant, KT is a correction coefficient based on the air-fuel ratio, water temperature, etc., and TD is an invalid injection time. That is, immediately after the idle switch is switched on, the ECU 50 prohibits the acceleration increase with respect to the fuel injection time TINJ, as shown in the time chart of FIG.

TINJ = C.A / N.KT + TD Then, when the idle switch continues to be ON even in the next control, and the determination in step S47 is No,
The ECU 50 proceeds to step S53 and determines whether or not the value of the second countdown timer TCD2 has become 0.
This determination is Yes until the predetermined time TS2 has elapsed, so the ECU 50 calculates the fuel injection time TINJ by prohibiting the acceleration increase in step S51.

On the other hand, the idle switch is turned from ON to OFF.
When the determination in step S45 is No (points d and e in FIG. 12) or the predetermined time TS2 has elapsed and the determination in step S47 is Yes (f in FIG. 12). , G point), the ECU 50 permits the acceleration increase, retrieves the acceleration increase value Tacc from the map of FIG. 13 based on the time change rate ΔA / N of the intake air amount in step S55, and then in step S57, performs the fuel injection according to the following equation. Calculate the time TINJ.

TINJ = C.A / N.KT + Tacc + TD Here, the reason why the acceleration increase is allowed when the idle switch is switched from ON to OFF or when the predetermined time TS2 elapses even when the idle switch is ON is: This is because the driver depresses the accelerator pedal to request acceleration, and the latter is because overmeasurement of the airflow sensor 6 due to backflow can be ignored in terms of time. As a situation in which the acceleration amount is increased while the idle switch is ON, there is a case where the load increases suddenly, such as when switching from the N range to the D range in the automatic transmission or when the clutch is connected in the manual transmission. To be Further, even if there is an acceleration increase request while the acceleration increase is prohibited and the acceleration increase is allowed thereafter, the acceleration increase (between points e and c in FIG. 12) due to the acceleration increase request is performed. Absent.

When the calculation of the fuel injection time TINJ in the fuel injection time calculation subroutine is completed, the ECU 50 drives the fuel injection valve 3 in step S15 of FIG. 3, returns to the start and repeats the control. Next, the aforementioned fully closed frequency correction value ΔFlog and ΔFlog learning subroutine will be described.

The frequency correction value ΔFlog at the time of full closure is ISC1
A correction value for compensating for secular change of 1 and the initial value is 0.
Is set to Also, turn off the ignition key
Even in the case of, the backup value is backed up by the in-vehicle battery so that the learning value is not erased. And EC
U50 is a predetermined learning interval (in this embodiment,
6.4 seconds), ΔFlog shown in the flowchart of FIG.
Repeat the learning subroutine.

When this subroutine is started, the ECU 5
In step S61, 0 is first read in the RAM with the operation information from the various sensors described above, and then in step S63,
It is determined whether or not learning is possible. If this determination is No (negative), the learning is not performed and the process returns to the start. The learning is performed under the following various conditions, that is, the water temperature WT is equal to or higher than a predetermined value (83 ° C. in this embodiment), the rotation speed feedback control of the ISC 11 is being executed, and the air conditioner switch is off.
That is, a predetermined range in which the output voltage V of the throttle sensor 10 is considered to be fully closed (in this embodiment, 0.2 V to
1.5V), and the change rate of the output voltage V of the throttle sensor 10 is a predetermined value (0.04V / in this embodiment).
Yes (affirmative) when all satisfying that the deviation between the target rotation speed NeO and the actual rotation speed NeR is less than or equal to a predetermined value (50 rpm in this embodiment).

When all the above-mentioned conditions are satisfied and the determination in step S63 is Yes, the ECU 50 determines in step S65 the current output frequency F of the air flow sensor 6.
It is determined whether or not real is equal to the theoretical frequency Flog calculated by the following formula. And if this determination is Yes,
It returns to the start without updating the frequency correction value ΔFlog when fully closed. Note that the determination in step S63 becomes Yes when the warm-up operation is completed, and the FIAV 21 is in the fully closed state. Therefore, the FIAV frequency FFIAV is not added in the following equation.

Flog = FISC + ΔFlog On the other hand, if the determination in step S65 is No, the ECU 50
Indicates that the output frequency Freal is the theoretical frequency F in step S67.
Determine if it is greater than log. Then, if this determination is Yes, in step S69 the fully closed frequency correction value Δ
A predetermined value α (1.56 Hz in this embodiment) is added to Flog, and if No, the predetermined value α is conversely subtracted from the fully closed frequency correction value ΔFlog in step S71. As a result, the fully closed frequency correction value ΔFlog is always learned and corrected, and the accuracy of the theoretical frequency Flog is maintained. Therefore, due to clogging of the throttle body 12, etc.
Even if the ISC frequency FISC commensurate with the opening of SC11 cannot be obtained, the A / N clip calculation subroutine can be correctly performed.

In the present embodiment, by performing the fuel injection control as described above, it is possible to suppress a transient deterioration of drivability and an increase in harmful exhaust gas components during deceleration operation while adopting a relatively simple processing procedure. I was able to. Although the description of the specific example is finished, the embodiment of the present invention is not limited to this example. For example, the above-described embodiment is one in which the present invention is applied to a fuel injection type internal combustion engine equipped with a turbocharger, but may be applied to one equipped with another supercharger such as a roots blower, or vaporization. It may be applied to those equipped with a container. Further, the present invention can be applied to an internal combustion engine that does not include a bypass passage or a bypass valve that communicates the downstream side and the upstream side of the supercharger, or an internal combustion engine that includes another type of air flow sensor such as a hot wire type. Is. Further, in the above embodiment, the intake air amount information is limited to the upper limit value or less when the deceleration operation state is detected, but may be limited when the high load operation state is changed to the low load operation state. However, instead of the intake air amount information, the fuel supply amount itself may be limited to the upper limit value or less. Incidentally, it is desirable that various judgment values, coefficients, etc. used for the above-mentioned control are appropriately set according to the characteristics of the air flow sensor, the supercharger and the like. Further, it is needless to say that the specific control procedure can be changed without departing from the gist of the present invention.

[0046]

According to the fuel supply control device of the first aspect of the present invention, a supercharger which is provided in an intake system of an internal combustion engine and pressurizes intake air to supply it to a combustion chamber of the internal combustion engine, An air flow sensor that is provided on the upstream side of the supercharger in the intake system and detects the intake air amount information of the internal combustion engine, and sets the fuel supply amount of the internal combustion engine based on the intake air amount information detected by the air flow sensor. Fuel supply amount setting means, operating state detecting means for detecting an operating state of the internal combustion engine, and the operating state detecting means detected that the internal combustion engine is in a decelerating operating state or a low load operating state lower than a predetermined load. At this time, since a limiter that limits at least one of the intake air amount information and the fuel supply amount to a predetermined limit range is provided, the pressurized intake air in the intake system is Even if the backflow to the sensor side causes the intake flow rate to be measured excessively or excessively, the intake air amount information or the fuel supply amount does not fall outside a certain limit range, resulting in overrich or over lean mixture. It is possible to suppress deterioration of drivability and increase of harmful exhaust gas components.

According to the fuel supply control device of the second aspect, in the fuel supply control device of the first aspect, the bypass provided in the intake system and connecting the downstream side and the upstream side of the supercharger. Since the bypass valve is provided in the bypass passage and is provided in the bypass passage and opens the bypass passage when the internal combustion engine is decelerated or the load is low, the bypass valve is opened by rapidly closing the throttle means, and the bypass valve is opened from the bypass passage. Even if the intake air that has recirculated to the upstream side of the turbocharger flows back to the air flow sensor side, the intake air amount information or the fuel supply amount does not exceed a certain limit range, and the air-fuel mixture becomes overrich or lean. It is possible to suppress the deterioration of drivability and the increase of harmful exhaust gas components due to.

Further, according to the fuel supply control device of the third aspect, in the fuel supply control device of the first or second aspect, the limiting means is in a stable idle state in which the value detected by the air flow sensor is stable. Since the limit range is set based on the intake air amount information detected by the air flow sensor, even if the intake air amount information changes due to clogging of the intake system, learning will keep the limit range at an appropriate value. And appropriate control is performed.

Further, according to the fuel supply control device of claim 4, in the fuel supply control device according to any one of claims 1 to 3, the limiting means sets the intake air amount information within the predetermined range. Due to the limitation, even if the pressurized intake air in the intake system flows back to the air flow sensor side and the intake flow rate is excessively measured, the fuel supply amount calculated from the intake air amount information has a limited range. The value does not become an outside value, so that deterioration of drivability and increase of harmful exhaust gas components due to overriching and over leaning of the air-fuel mixture can be suppressed.

According to a fifth aspect of the fuel supply control device, in the fuel supply control device according to any one of the first to fourth aspects, the fuel supply control device is provided in the intake system downstream of the supercharger. A throttle means for adjusting an intake air amount of the internal combustion engine according to an artificial operation; an idle intake air amount adjusting means for adjusting an intake air amount when the internal combustion engine is in an idle operation state; and an idle intake air amount adjusting means. Since the setting means for setting the limit range according to the operating state is provided, even if the intake flow rate is excessively or excessively measured by the air flow sensor when the throttle means is fully closed, it is calculated from the intake air amount information. The amount of fuel supply does not fall outside a certain limit range, which deteriorates drivability and increases harmful exhaust gas components due to overriching and over leaning of the air-fuel mixture. It can be suppressed.

According to a sixth aspect of the fuel supply control device of the present invention, in the fuel supply control device of the fifth aspect, the setting means calculates the limit range from the operating state of the idle intake air amount adjusting means. Since the setting is made based on the intake air amount information, the upper limit value is set with high accuracy, and it is possible to prevent the air-fuel mixture from becoming rich or rich. Further, according to the fuel supply control device of claim 7, in the fuel supply control device of claim 5, the limit range is not less than a predetermined lower limit value and not more than a predetermined upper limit value, and the setting means is It is obtained by temporarily reducing the value set based on the theoretical intake air amount information calculated from the operating state of the idle intake air amount adjusting means and the intake air amount information detected by the air flow sensor at the start of deceleration operation at a predetermined gradient. Since the larger value is set as the upper limit value, the upper limit value is set in response to a transient change in the intake air amount at the time of entering the deceleration operation, and the drivability and the like are further improved.

Further, according to the fuel supply control device of the eighth aspect, in the fuel supply control device according to any one of the first to seventh aspects, the intake amount information or the fuel supply amount of the limiting means is controlled. Since the restriction is released after a lapse of a predetermined time after entering the deceleration operation, the normal fuel supply control is quickly returned to when the overflow or undermeasurement of the air flow sensor due to the backflow of the intake air disappears. As a result, overcontrol is prevented.

According to a ninth aspect of the fuel supply control apparatus of the present invention, in the fuel supply control apparatus of any one of the first to eighth aspects, the driving state detecting means determines that the traveling speed of the vehicle is a predetermined value. Since the deceleration or the low load operation is detected when the throttle opening is equal to or less than the predetermined opening degree, the deceleration or the low load operation is surely detected, and unnecessary control is not performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an engine control system to which a fuel injection device according to the present invention is applied.

FIG. 2 is a flowchart showing a processing procedure of a fuel injection control main routine.

FIG. 3 is a flowchart showing a processing procedure of a fuel injection control main routine.

FIG. 4 is a flowchart showing a processing procedure of an A / N clip calculation subroutine.

FIG. 5 is a flowchart showing a processing procedure of a TINJ calculation subroutine.

FIG. 6 is a flowchart showing a processing procedure of a ΔFlog learning subroutine.

FIG. 7 is a graph showing an outline of control in the embodiment.

FIG. 8 is a map showing the relationship between ISC opening and ISC output frequency.

FIG. 9 is a map showing the relationship between cooling water temperature and FIAV frequency.

FIG. 10 is a graph showing the relationship between the elapsed time after entering the deceleration operation and the second upper limit clip value A / NHclip 2.

FIG. 11 is a graph showing the relationship between the elapsed time after entering the deceleration operation and the upper limit clip value A / NHclip.

FIG. 12 is a time chart showing the relationship between ON / OFF of the idle switch and acceleration increase.

FIG. 13 is a map showing the relationship between the time change rate of the intake air amount and the acceleration increase value.

[Explanation of symbols]

 1 Engine 3 Fuel Injection Valve 4 Intake Manifold 6 Air Flow Sensor 8 Intake Pipe 9 Throttle Valve 10 Throttle Sensor 11 ISC 12 Throttle Body 15 Exhaust Manifold 21 FIAV 22 Water Temperature Sensor 23 Crank Angle Sensor 34 Turbocharger 41 Bypass Pipe 42 Bypass Valve 47 Air Pipe 50 ECU

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02D 41/18 C 45/00 312 F J 366 H C (72) Inventor Takanori Fujimoto Himeji City, Hyogo Prefecture 840 Chiyoda-cho Mitsubishi Electric Corporation Himeji Works

Claims (9)

[Claims] 1. A supercharger, which is provided in an intake system of an internal combustion engine and pressurizes intake air to supply it to a combustion chamber of the internal combustion engine; and a supercharger provided in the intake system upstream of the supercharger. An air flow sensor for detecting intake air amount information of the internal combustion engine, a fuel supply amount setting means for setting a fuel supply amount of the internal combustion engine based on the intake air amount information detected by the air flow sensor, and an operating state of the internal combustion engine At least one of the intake air amount information and the fuel supply amount when the internal combustion engine is detected to be in a deceleration operating state or a low load operating state lower than a predetermined load by the operating state detecting means. Is provided within a predetermined limit range, and a fuel supply control apparatus for an internal combustion engine with a supercharger. 2. A bypass passage which is provided in the intake system and which communicates a downstream side and an upstream side of the supercharger with each other, and the bypass passage which is provided in the bypass passage when the internal combustion engine is decelerated or operated under a low load. 2. A fuel supply control device for an internal combustion engine with a supercharger according to claim 1, further comprising a bypass valve that opens. 3. The limiting means sets the limiting range based on the intake air amount information detected by the air flow sensor in a stable idle state where the detection value by the air flow sensor is stable. A fuel supply control device for an internal combustion engine with a supercharger according to claim 1 or 2. 4. The internal combustion engine with a supercharger according to claim 1, wherein the limiting means limits the intake air amount information to the predetermined range. Fuel supply control device. 5. Throttle means provided downstream of the supercharger in the intake system for adjusting the intake air amount of the internal combustion engine in accordance with an artificial operation; and a throttle means when the internal combustion engine is in an idle operation state. 5. An idle intake air amount adjusting means for adjusting an intake air amount, and a setting means for setting the limit range according to an operating state of the idle intake air amount adjusting means. 2. A fuel supply control device for an internal combustion engine with a supercharger according to item 1. 6. The internal combustion engine with a supercharger according to claim 5, wherein the setting means sets the limit range based on theoretical intake air amount information calculated from an operating state of the idle intake air amount adjusting means. Engine fuel supply control device. 7. The limit range is a range of a predetermined lower limit value or more and a predetermined upper limit value or less, and the setting unit sets based on theoretical intake air amount information calculated from an operating state of the idle intake air amount adjusting unit. And a value obtained by temporarily reducing the intake air amount information detected by the air flow sensor at the start of deceleration operation at a predetermined gradient, the larger one is set as the upper limit value. The fuel supply control device for an internal combustion engine with a supercharger according to claim 5. 8. The method according to claim 1, wherein the restriction of the intake air amount information or the fuel supply amount by the restriction means is canceled when a predetermined time has elapsed after the entry of the deceleration operation.
7. The fuel supply control device for an internal combustion engine with a supercharger according to any one of 7 above. 9. The driving state detecting means detects that the vehicle is decelerating or operating under a low load when the traveling speed of the vehicle is a predetermined value or less and the throttle means is a predetermined opening or less. , Any one of claims 1 to 8
Item 7. A fuel supply control device for an internal combustion engine with a supercharger according to item.