JP2696779B2 - 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 a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that controls a fuel supply amount and an ignition timing according to an operating state of the engine.

[0002]

2. Description of the Related Art Conventionally, an exhaust passage of an internal combustion engine has been used.
It is known that a plurality of catalyst devices (first and second catalyst devices) are arranged in series. According to the control device for an internal combustion engine, the first catalyst device having a relatively small volume is disposed near the engine, and the activation of the catalyst device at the time of low temperature start is promoted, so that the engine is efficiently started at the time of low temperature start of the engine. It is possible to purify exhaust gas. However, in this device, since the first catalyst device is disposed in the exhaust passage near the engine, the first catalyst device is exposed to high-temperature exhaust gas for a long time after the engine is warmed up. As a result, there is a disadvantage that the catalyst is severely deteriorated and the life of the catalyst is short.

[0003] In order to solve such a drawback, a bypass passage for bypassing the first catalyst device and an exhaust gas from the engine are provided in the exhaust passage of the internal combustion engine.
An exhaust gas purifying apparatus for an internal combustion engine having a switching valve for switching to the catalyst device side or the bypass passage side has already been proposed (for example, Japanese Utility Model Laid-Open No. 52-135713).

According to this conventional technique, exhaust gas can be efficiently purified through the first catalyst device at the time of low temperature start, while the switching valve is moved to the bypass passage side after the engine warm-up. By performing the switching, the exhaust gas is purified only by the second catalyst device, and the durability of the first catalyst device can be improved.

[0005]

However, according to the above-mentioned prior art, when the switching valve is switched to communicate the exhaust passage with the first catalyst device side, the exhaust pressure increases and the scavenging efficiency of the engine increases. Engine intake efficiency (η
On the other hand, when the exhaust passage is switched to the bypass passage side, the exhaust pressure is reduced and the scavenging efficiency of the engine is increased, so that the intake efficiency (ηV) of the engine is increased. Since the fuel supply and the ignition timing are not set according to the change of the characteristic of the intake efficiency (ηV), there is a problem that the air-fuel ratio of the air-fuel mixture is not stabilized and the emission characteristic is deteriorated.

The present invention has been made to solve such a conventional problem. Even if the exhaust passage is switched, the air-fuel ratio of the air-fuel mixture is set to a desired air-fuel ratio to improve the emission characteristics of the exhaust gas. It is an object of the present invention to provide a control device for an internal combustion engine that can perform the following.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first catalyst device disposed in an exhaust passage near an internal combustion engine and the first catalyst device downstream of the first catalyst device. A second catalyst device disposed in the exhaust passage, a bypass passage that bypasses the first catalyst device, and an exhaust gas from the engine that is provided on one of the first catalyst device side and the bypass passage side. on the other hand a switching means for switching to less
Both the engine speed and the load state of the engine
Operating state detection for detecting an operating state of the engine including:
Means, based on the detection result of the operating state detection means,
Basic system for calculating the basic control amount of fuel supply to the engine
Control amount calculating means, and injected into an intake pipe of the engine.
The amount of fuel adhering to the wall of the intake pipe,
Fuel adhering to the wall of the trachea evaporates and the engine
Considering the amount of fuel taken away to the combustion chamber,
The control apparatus for an internal combustion engine with adhesion correction means <br/> and for performing fuel supply amount of the adhesion correction to the engine, the attachment
The correction unit is configured to detect the adhesion according to a switching state of the switching unit.
The amount of attached fuel used in the correction means and the carry-off
It is characterized by having a changing means for changing the fuel amount .

[0008]

According to the above arrangement, according to the switching state of the exhaust passage.
To change the amount of deposited fuel and the amount of removed fuel.
The exhaust gas is switched
To accurately predict the effect of fuel attached to the intake pipe,
The air-fuel ratio of the mixture supplied to the combustion chamber
Control to improve emission characteristics of exhaust gas.
Can be.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of a control device for an internal combustion engine according to the present invention.

In FIG. 1, reference numeral 1 denotes a DOHC in-line four-cylinder internal combustion engine (hereinafter, simply referred to as "engine") in which each cylinder is provided with a pair of intake valves and exhaust valves (not shown). In the engine 1, the valve timing (valve lift amount, valve opening period) of the intake valve and the exhaust valve is adjusted to a high-speed valve timing (hereinafter, referred to as "HIV") suitable for a high-speed rotation region of the engine.
/ T ”) and a low-speed valve timing suitable for the low-speed rotation region (hereinafter referred to as“ LOV / T ”).

More specifically, the valve timing switching mechanism 21 has a solenoid valve (not shown) for controlling the switching of the valve timing. The solenoid valve is an electronic control unit (hereinafter referred to as "ECU"). 5),
The opening / closing operation is controlled by the ECU 5. That is,
The solenoid valve switches the hydraulic pressure of the valve timing switching mechanism 21 between high and low, and the valve timing is switched between high-speed V / T and low-speed V / T in accordance with the high / low of the hydraulic pressure. The hydraulic pressure of the valve timing switching mechanism 21 is
The pressure is detected by the oil pressure (Poil) sensor 22, and the detection signal is supplied to the ECU 5.

A throttle body 3 is provided in the middle of an intake pipe 2 of the engine 1, and a throttle valve 3 'is provided therein.
Is arranged. Further, a throttle valve opening (θTH) sensor 4 is connected to the throttle valve 3 ′, and outputs an electric signal corresponding to the opening of the throttle valve 3 ′ to output a signal from the ECU 5.
To supply.

The fuel injection valve 6 is connected between the engine 1 and the throttle valve 3 'and to a fuel pump (not shown) of the intake pipe 2 and is also electrically connected to the ECU 5, and
The valve opening time of fuel injection is controlled by a signal from U5.

A branch pipe 7 is provided downstream of the throttle valve 3 ′ of the intake pipe 2, and an absolute pressure (PBA) sensor 8 is attached to a tip of the branch pipe 7. The PBA sensor 8 is electrically connected to the ECU 5, and
The absolute pressure PBA is converted into an electric signal by the PBA sensor 8 and supplied to the ECU 5.

An intake air temperature (TA) sensor 9 is mounted on the pipe wall of the intake pipe 2 downstream of the branch pipe 7, and the intake air temperature TA detected by the TA sensor 9 is converted into an electric signal.
It is supplied to the ECU 5.

An engine coolant temperature (TW) sensor 10 composed of a thermistor or the like is inserted into the cylinder peripheral wall of the cylinder block of the engine 1 filled with coolant, and the engine coolant temperature TW detected by the TW sensor 10 is converted into an electric signal. The converted data is supplied to the ECU 5.

A cylinder discrimination (CYL) is provided at a predetermined position around the camshaft (not shown) or around the crankshaft of the engine 1.
The sensor 11 and the NE sensor 12 are respectively mounted.

The CYL sensor 11 outputs a pulse signal (hereinafter, referred to as "CYL signal pulse") at a predetermined crank angle position of a specific cylinder every two revolutions of the crankshaft, and NE
The sensor 12 outputs a signal pulse (hereinafter referred to as “T”) at a predetermined crank angle position every 180 ° rotation of the crankshaft of the engine 1.
The CYL signal pulse and the TDC signal pulse are supplied to the ECU 5.

The ignition plug 23 of each cylinder of the engine 1
The ignition timing is controlled by the ECU 5.

An exhaust pipe (exhaust passage) 14 of the engine 1
An oxygen concentration sensor (hereinafter referred to as an “O2 sensor”) 15 is provided near the engine. The O2 sensor 1
5 is a sensor element having a zirconia solid electrolyte (ZrO ₂ )
The output signal is inverted from a lean signal to a rich signal or from a rich signal to a lean signal at the stoichiometric air-fuel ratio. That is, the output signal of the O2 sensor 15 has a high level on the rich side of the exhaust gas and has a low level on the lean side.
5

A first catalytic device 16 and a second catalytic device 17 are arranged in series in the exhaust pipe 14 downstream of the O2 sensor 15.

The first catalyst device 16 is provided for quickly activating the first catalyst device 16 when the engine 1 is started at a low temperature to improve the emission characteristics of exhaust gas at the time of low temperature start. The second catalyst device 17 is formed to have a smaller capacity than that of the second catalyst device 17. The first and second catalyst devices 16 and 17 control the amount of HC and C in the exhaust gas.
Harmful components such as O and NOx are purified. Further, an exhaust communication passage (hereinafter, referred to as a “bypass passage”) 14 a that bypasses the first catalyst device 16 side is provided to branch off from the exhaust pipe 14 on the downstream side of the O2 sensor 15. That is,
The bypass passage 14 a has one end connected to the exhaust pipe 14 on the upstream side of the first catalyst device 16 and the other end connected to the first catalyst device 1.
6 is connected to the exhaust pipe 14 on the downstream side.

In an exhaust pipe 14 at a branch point between the upstream side of the first catalytic device 16 and the bypass passage 14a, exhaust gas from the engine is supplied with the first catalytic device 16 and the bypass passage 14a.
A switching valve (bypass valve, hereinafter referred to as “BPV”) 18 is provided as switching means for switching to the “a” side.
(For example, a solenoid valve, a motor, and the like).

The electric actuator 19 is connected to the ECU 5 and is driven by a signal from the ECU 5. That is, the BPV 18 is switched by the driving of the electric actuator 19, and the exhaust gas from the engine can be switched between the first catalyst device 16 side and the bypass passage 14a side.

When the electric actuator 19 is not operated (hereinafter referred to as "BPV OFF"), the BPV 18 is deenergized so that exhaust gas from the engine is directed to the bypass passage 14a side, and when the electric actuator 19 is operated (hereinafter referred to as "BPV OFF"). ,
"BPV ON") is urged so that the exhaust gas is directed to the first catalyst device 16 side. That is,
The BPV 18 is set at the position shown by the solid line in FIG. 1 when the BPV is off, and at the position shown by the broken line in FIG. 1 when the BPV is on.

At the branch point between the first catalyst device 16 and the bypass passage 14a, the BPV 18 determines whether the exhaust gas passage is switched to the first catalyst device 16 or the bypass passage 14a. A BPV position detection sensor (hereinafter, referred to as “BP sensor”) 20 for detecting the position of the BPV 18 is provided, and the BP sensor 20 detects the position of the BPV 18 and outputs an electric signal to the ECU 5. Also, BPV
Since 18 is driven by the electric actuator 19 in response to a signal from the ECU 5, the position of the BPV 18 may be detected by a drive signal of the electric actuator 19 output from the ECU 5. The BP sensor 20 is provided by B
This is to improve the controllability by reliably detecting the position of the BPV 18 even when the operation of the PV 18 or the electric actuator 19 is delayed due to deterioration or the like.

The ECU 5 has an input circuit 5a having functions of shaping input signal waveforms from the above-mentioned various sensors, correcting a voltage level to a predetermined level, converting an analog signal value to a digital signal value, and the like, and a central processing unit. Circuit (hereinafter “CP
U) 5b, storage means 5c comprising a ROM and a RAM for storing various calculation programs executed by the CPU 5b, various maps and calculation results to be described later, the fuel injection valve 6, the electric actuator 19, and a switching mechanism. 21
And an output circuit 5d for supplying a drive signal to the ignition plug 23 and the ignition plug 23.

FIGS. 2 and 3 are flowcharts of a program for calculating the opening time of the fuel injection valve 6, ie, the fuel injection time (fuel injection amount) Tout and the ignition timing θIG of the ignition plug 23 (first embodiment). Example). This program
It is executed in synchronization with the generation of the TDC signal pulse.

First, in step S1, "BPV OF
F "is determined, and if the answer is affirmative (YES), that is, if the exhaust gas passage is set on the bypass passage 14a side, the process proceeds to step S2 to determine whether the valve timing is at HIV / T. It is determined whether or not.

If the answer to step S2 is negative (NO), that is, if the valve timing is at LO V / T, the process proceeds to step S3, where Ti for LO V / T and BPV OFF is turned off.
Search for the basic fuel injection amount T
iM and the basic ignition timing θIGM are calculated.

The Ti map and the θIG map specifically show the engine speed NE as shown in FIGS. 4 (a) and 4 (b).
1 to NE20 and the absolute pressure PBA1 to PBA17 in the intake pipe
On the other hand, TiM (1, 1) to TiM (20, 17) and θIGM (1, 1) to θIGM (20, 17) are provided in a matrix, and the basic fuel injection amount TiM and the basic ignition timing θIGM Is the Ti map and θI
It is read out by searching the G map or calculated by an interpolation operation method.

In step S3, the basic fuel injection amount TiM
And the basic ignition timing θIGM is LOV / T, BPV OF
From the Ti map and θIG map for F, the NE value and P
The data is read out according to the detected value of the BA value. At this time, the interpolation calculation is performed as necessary, so that the LO V / T, BPV
Basic fuel injection amount TiM for OFF and basic ignition timing θI
GM is calculated.

Next, in steps S4 and S5, the amount of fuel adhering to the intake pipe wall of the fuel injected into the intake pipe of the engine and the amount of adhering fuel adhering to the intake pipe wall evaporate to produce a combustion chamber of the engine. Is carried out in consideration of the amount of fuel removed.

First, in step S4, LO V / T, B
The direct rate A and the carry-out rate B for PV OFF are calculated. Here, the direct rate A is the proportion of the fuel injected into a combustion chamber in a form that includes the amount sucked by evaporation or the like during the cycle out of the fuel injected in a certain cycle, and the carry-off rate B Is the proportion of fuel that has been drawn into the combustion chamber due to evaporation or the like during the cycle of the fuel that has adhered to the intake pipe wall up to the previous time. The direct rate A and the carry-out rate B are L set according to the engine coolant temperature TW and the intake pipe absolute pressure PBA.
A map and a B map (not shown) for OV / T and BPV OFF are searched according to the detected values of the TW value and the PBA value. At this time, by performing an interpolation operation as needed, the direct rate A for LO V / T and BPV OFF can be obtained.
And the carry-out rate B are calculated.

In the following step S5, LO V / T, B
The correction coefficients KA and KB of the direct rate A and the carry-off rate B for PV OFF are calculated, and the process proceeds to step S16. The correction coefficients KA and KB are calculated as LO V / T, BP shown in FIG.
By the KA table and the KB table for V OFF,
It is set according to the engine speed NE. That is, the correction coefficient KA of the direct rate A and the correction coefficient KB of the carry-out rate B are
Each is set so as to increase as the NE value increases.

Here, when the engine speed NE increases, the correction coefficients KA and KB are increased because the intake flow velocity in the intake pipe is increased, so that the direct rate A and the carry-out rate B apparently increase. Because it becomes.

On the other hand, if the answer in step S2 is affirmative (YE
In the case of S), the basic fuel injection amount Ti for HIV / T and BPV OFF is set in the same manner as in steps S3 to S5.
M, basic ignition timing θIGM, direct rate A and carry-out rate B
And the correction coefficients KA and KB are calculated (steps S6 to S6).
8) Go to step S16.

That is, in step S6, H substantially the same as in FIG.
From the Ti / θIG map for IV / T and BPV OFF, the basic fuel injection amount TiM and the basic ignition timing θIG
M is searched, and then the A map and the B map (not shown) for HIV / T and BPV OFF are searched to calculate the direct rate A and the carry-out rate B (step S7). Then, after that, the HIV / T, BPV shown in FIG.
The KA table and the KB table for OFF are searched, and the correction coefficient KA for HIV / T, BPV OFF,
KB is calculated (step S8).

If the answer to step S1 is negative (N
O), that is, when the BPV 18 is set to the first catalyst device 16 side with the BPV ON, the process proceeds to step S9, and it is determined whether or not the valve timing is at HIV / T.

If the answer to step S9 is negative (NO), that is, L
When it is at OV / T, the basic fuel injection amount TiM for LOV / T, BPV ON, the basic ignition timing θIGM, the direct rate A, the carry-out rate B, and the correction coefficient are set in the same manner as in steps S6 to S8. KA and KB are calculated (steps S10 to S12), and the process proceeds to step S16.

That is, in step S10, the basic fuel injection amount TiM and the basic ignition timing θIG are obtained from the Ti map and the θIG map for LOV / T and BPV ON substantially similar to those in FIG.
Search for M. In step S11, LO V / T, B
The A map and the B map (not shown) for PV ON are searched to calculate the direct rate A and the carry-out rate B. In step S12, LO V / T, BPV shown in FIG.
The KA table and the KB table for ON are searched, and L
The correction coefficients KA and KB for OV / T and BPV ON are calculated.

When the answer to step S9 is affirmative (YES), HI is set in the same manner as in steps S10 to S12.
The basic fuel injection amount TiM for V / T and BPV ON, the basic ignition timing θIGM, the direct rate A and the carry-out rate B, and the correction coefficients KA and KB are calculated (steps S13 to S1).
5) Go to step S16.

That is, in step S13, the basic fuel injection amount TiM and the basic ignition timing θIGM are searched from the HIG / T, BPV ON Ti map and θIG substantially the same as in FIG. 4, and in step S14, the HIV / T T, BPVO
Search A map and B map (not shown) for N,
The direct rate A and the carry-out rate B are calculated, and in step S15, the HI table is searched for the HI V / T and BPV ON KA table and the KB table shown in FIG.
The correction coefficients KA and KB for T and BPV ON are calculated.

The basic fuel injection amount TiM, basic ignition timing θIGM, direct rate A and carry-out rate B are all BP.
The above-mentioned Ti map, θIG map, A map, B map, KA table, and KB table are set corresponding to this tendency in order to show a different tendency depending on ON / OFF of V18 and each valve timing.

Thus, HI V / T, LO V / T,
The four types of Ti maps, θIG maps, A maps, and B maps, which are different depending on the conditions of BPV OFF and BPV ON, and the KA table and the KB table are provided because the intake efficiency of the engine caused by switching the exhaust gas passage ( This is to cope with fluctuations in flow velocity near the intake valve, which is one of the dominant factors of the fuel transfer parameters caused by the valve timing of the intake valve, and pressure fluctuations caused by the fluctuation of ηV).

In the following step S16, the following equation (1) is obtained.
According to (2), the corrected direct rate Ae and the corrected carry-out rate Be
Is calculated, (1-Ae) and (1-Be) are calculated (step S17), and the process proceeds to step S18 (FIG. 3).

Ae = A × KA (1) Be = B × KB (2) In step S18, it is determined whether or not the engine is in a start mode. When the answer is affirmative (YES), the basics for starting are determined. The fuel injection amount Tout is calculated based on the fuel amount Ti (step S24), and the process proceeds to step S25.

If the answer to step S18 is negative (NO), that is, if the engine is not in the start mode, an addition correction term Ttota described later is used.
The required fuel amount Tcyl (N) for each cylinder not including l is calculated by the following equation (3) (step S19).

Tcyl (N) = TiM × Ktotal (N) (3) Here, (N) indicates a cylinder number, and a parameter to which this is assigned is calculated for each cylinder. TiM is the basic fuel amount calculated in any of steps S3, S6, S10, and S13. Ktotal (N) is the product of all correction coefficients (for example, engine water temperature correction coefficient KTW, lean correction coefficient KLS, etc.) calculated based on engine operation parameter signals from various sensors. However, the air-fuel ratio correction coefficient KO2 calculated according to the output of the O2 sensor 15 is not included.

In step S20, the following equation (4) is used.
The fuel supply amount TNET, which is the amount of fuel to be supplied to the combustion chamber of the corresponding cylinder by the current fuel injection, is calculated.

TNET = Tcyl (N) + Ttotal−Be × TWP (N) (4) where Ttotal is all addition correction terms calculated based on engine operation parameter signals from various sensors (for example, acceleration increase correction). Term TACC). However, it does not include the invalid time TV described later. TWP (N)
Is the intake pipe adhering fuel amount (predicted value) calculated by executing the flowchart of FIG. 6 described later, and (Be × TWP)
(N)) corresponds to the carry-out fuel amount in which the fuel attached to the intake pipe is carried away to the combustion chamber. Since there is no need to newly inject the removed fuel amount, Tcyl in equation (4) is used.
This amount is subtracted from the (N) value.

In step S21, it is determined whether or not the TNET value calculated by the equation (4) is larger than 0. If the answer is negative (NO), that is, if TNET ≦ 0, the fuel injection amount Tout is set to 0. Proceed to step S25. On the other hand, the answer to step S21 is affirmative (YES), that is, TNE
When T> 0, the Tout value is calculated by the following equation (5), and the process proceeds to step S25.

Tout = TNET (N) / Ae × KO2 + TV (5) Here, KO2 is an air-fuel ratio correction coefficient calculated based on the output of the O2 sensor 15, and TV is an invalid time correction term.

By opening the fuel injection valve 6 by the Tout value calculated by the equation (5), (TN)
An amount of fuel corresponding to ET (N) × KO2 + Be × TWP (N)) is supplied.

In step S25, the following equation (6) is used.
The θIG value is calculated and the program ends.

ΘIG = θIGM + θIGK (6) Here, θIGM is calculated in steps S3, S6, S10,
This is the basic ignition timing calculated in any of S13.

ΘIGK is a correction value calculated by a subroutine (not shown) according to various engine parameter signals such as water temperature TW, intake air temperature TA, engine operation mode, acceleration / deceleration state, and exhaust gas recirculation rate in the exhaust gas recirculation system. .

The ignition timing θIG of the ignition plug 23 of each cylinder of the engine 1 is controlled based on the θIG value calculated by the above equation (6).

As described above, in the present embodiment, the fuel injection amount Tout and the ignition timing θIG are appropriately adjusted according to the switching state of the exhaust gas passage and the switching state of the valve timing by the programs in FIGS. Thus, the air-fuel ratio in the exhaust gas of the engine can be stabilized, and the emission characteristics can be improved.

Further, in this embodiment, the direct rate A and the carry-out rate B are calculated and corrected according to the switching state of the exhaust gas passage and the switching state of the valve timing.
In each exhaust gas passage switching state and valve timing switching state, it is possible to accurately predict the effect of the amount of fuel attached to the intake pipe and accurately control the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber to a desired value. it can.

FIG. 6 is a flowchart of a program for calculating the amount of fuel TWP (N) attached to the intake pipe. This program is used to generate a crank angle pulse that is generated every time the crankshaft rotates a predetermined angle (for example, 30 degrees). Executed synchronously.

In step S31, it is determined whether or not the current execution of the program is within a period from the start of the calculation of the fuel injection time Tout to the end of the fuel injection (hereinafter referred to as "injection control period"). If affirmative (YES), the first flag FCTWP (N) is set to a value of 0 (step S42), and the program ends. If the answer to step S31 is negative (NO), that is, if it is not within the injection control period, the first flag FCTWP (N) is set to the value 1
Is determined (step S32). When this answer is affirmative (YES), that is, when FCTWP (N) = 1, the process immediately proceeds to step S41, and when negative (NO), that is, FC
When TWP (N) = 0, it is determined whether or not fuel cut (fuel supply cutoff) is being performed (step S33).

When the answer to step S33 is negative (NO), that is, when fuel cut is not being performed, the intake pipe adhering fuel amount TWP (N) is calculated by the following equation (7) (step S33).
34), the second flag FTWPR (N) is set to a value of 0, and the first flag FCTWP (N) is set to a value of 1 (steps S40, S41), and the program ends.

TWP (N) = (1−Be) × TWP (N) (n−1) + (1−Ae) × (Tout (N) −TV) (7) where TWP (N) (n -1) is the previous value of TWP (N), and Tout (N) is the latest fuel injection amount calculated by the program in FIGS. Also, the first on the right side
The term corresponds to the amount of fuel that has not been removed this time among the fuel that was previously deposited, and the second term on the right side corresponds to the amount of fuel that has newly adhered to the intake pipe of the fuel injected this time. I do.

If the answer in step S33 is affirmative (YE
S), that is, during fuel cut, it is determined whether or not the second flag FTWPR (N) has a value of 1 (step S35). This answer is affirmative (YES), that is, FTW
When PR (N) = 1, the process immediately proceeds to step S41, and when negative (NO), that is, when FTWPR (N) = 0, the attached fuel amount TWP (N) is calculated by the following equation (8) (step S36). The process proceeds to step S37.

TWP (N) = (1−Be) × TWP (N) (n−1) (8) Equation (8) corresponds to the above equation (1) with the second term on the right-hand side deleted. . This is because the fuel is being cut and there is no newly attached fuel.

In step S37, it is determined whether or not the TWP (N) value is greater than a small predetermined value TWPLG. If the answer is affirmative (YES), that is, if TWP (N)> TWPLG, the process proceeds to step S40. If the answer to step S37 is negative (NO), that is, if TWP (N) ≦ TWPLG, then TWP (N) = 0 (step S38), and the second
The flag FTWPR (N) is set to a value of 1 (step S39), and the process proceeds to step S41.

As described above, the fuel quantity TWP (N) adhering to the intake pipe can be accurately calculated by the program of FIG. 6, and the calculated TWP (N) value can be calculated by using the program shown in FIG.
By using the program of FIG. 3 to calculate the fuel injection amount Tout, an appropriate amount of fuel is supplied to the combustion chamber of each cylinder in consideration of the amount of fuel attached to the intake pipe and the amount of fuel removed from the attached fuel. be able to.

FIGS. 7 and 8 are flowcharts showing a program (second embodiment) for calculating the fuel injection amount Tout and the ignition timing θIG. This program is executed in synchronization with the generation of the TDC signal pulse. .

First, in a step S61, it is determined whether or not the valve timing is "HIV / T". When the answer to step S61 is negative (NO), that is, when the valve timing is "LO V / T", the process proceeds to step S62 to calculate the basic fuel injection amount TiM for LO V / T and the basic ignition timing θIGM.

The basic fuel injection amount TiM for LO V / T,
The basic ignition timing θIGM is a T for LO V / T set according to the engine speed NE and the intake pipe absolute pressure PBA.
A search is performed from the i map and the θIG map (not shown) according to the detected values of the NE value and the PBA value. At this time, the basic fuel injection amount TiM for LO V / T and the basic ignition timing θIGM are calculated by performing an interpolation operation as needed.

Next, in step S63, the direct rate A and the carry-out rate B for LOV / T are calculated. The direct rate A and the carry-out rate B are the engine water temperature TW and the absolute pressure P in the intake pipe.
A LO V / T A map and a B map (not shown) set according to the BA are searched according to the detected values of the TW value and the PBA value. At this time, the direct ratio A and the carry-out ratio B for LO V / T are calculated by performing an interpolation operation as needed.

In the following step S64, the correction coefficients KA and KB for the direct rate A and the carry-out rate B for LOV / T are calculated, and the flow advances to step S68. In step S64,
The correction coefficients KA and KB are calculated as LO V /
The KA table and the KB table for T are searched according to the engine speed NE.

On the other hand, if the answer in step S61 is affirmative (Y
ES), the basic fuel injection amount TiM for HIV / T, the basic ignition timing θIGM, the direct rate A and the carry-out rate B, and the correction coefficients KA and KB are calculated in the same manner as in steps S62 to S64 (step S62). S65-S67),
Proceed to step S68.

That is, in step S65, the basic fuel injection amount TiM and the basic ignition timing θIGM are retrieved from the HI V / T Ti map and θIG map (not shown), and in step S66, the HI V / T A Searching the map and the B map (not shown), the direct rate A and the carry-out rate B
Is calculated, and in step S67, the HI shown in FIG.
The KA table and the KB table for the V / T are searched to calculate the correction coefficients KA and KB for the HIV / T.

In the following step S68, “BPV OF
F ", the answer is negative (NO), that is, if the exhaust gas passage is set to the first catalyst device 16 side, the process proceeds to step S69, and the direct rate A for BPV ON is determined. Correction coefficient KAB and correction coefficient KB for carry-out rate B
B is calculated respectively.

Here, the correction coefficient KAB of the direct rate A for BPV ON and the correction coefficient KBB of the carry-out rate B are calculated based on the engine speed NE and the absolute pressure PBA in the intake pipe. And a KBB map (not shown) according to the detected values of the NE value and the PBA value. At this time, by performing an interpolation operation as needed, the correction coefficient KAB of the direct rate A for BPV ON
The correction coefficient KBB of the carry-out rate B is calculated.

In the following step S70, a correction coefficient KTiB of the basic fuel injection amount TiM for BPV ON is calculated.

Here, the correction coefficient KTiB of the basic fuel injection amount TiM for BPV ON is determined according to the engine speed NE and the intake pipe absolute pressure PBA.
NE value and PB from KTiB map (not shown)
The search is performed according to the detected value of the A value. At this time, the correction coefficient KTiB of the basic fuel injection amount TiM for BPV ON is calculated by performing an interpolation operation as needed.

In the following step S71, a correction coefficient KθIGB of the ignition timing θIG for BPV ON is calculated, and the routine proceeds to step S75.

Here, the ignition timing θIG for BPV ON
Is obtained from a KPVIGB map (not shown) for BPV ON set in accordance with the engine speed NE and the intake pipe absolute pressure PBA.
It is read according to the detected value of the value. At this time, an interpolation operation is performed as necessary, whereby a correction coefficient KθIGB of the ignition timing θIG for BPV ON is calculated.

On the other hand, if the answer to step S68 is affirmative (YES), the flow proceeds to step S72, where the direct rate A
And the correction coefficient KBB of the carry-out rate B are set to a value of 1, respectively. Subsequently, steps S73 and S74
, The correction coefficient KTiB of the basic fuel injection amount TiM and the correction coefficient KθIGB of the ignition timing θIG each have a value of 1
And proceed to step S75.

Here, when the BPV is turned off, each correction coefficient K
AB, KBB, KTiB, and KθIGB each have a value of 1.
The reason is that when the BPV is OFF, the exhaust gas passage is on the exhaust bypass passage 14a side and the intake efficiency of the engine (η
This is because V) does not decrease, and therefore no correction is required.

In the following step S75, the following equation (9) is obtained.
According to (10), the corrected direct rate Ae and the corrected carry-out rate B
e, (1-Ae) and (1-Be) are calculated (step S76), and the process proceeds to step S77 (FIG. 8).

Ae = A × KA × KAB (9) Be = B × KB × KBB (10) In step S77, it is determined whether or not the engine is in a start mode. When the answer is affirmative (YES), The fuel injection amount Tout is calculated based on the basic fuel amount Ti for starting, and the ignition timing θIG is calculated based on the ignition timing θIG for starting (steps S84 and S85), and the program ends.

If the answer to step S77 is negative (NO), that is, if the engine is not in the start mode, the required fuel amount Tcyl (N) for each cylinder is calculated by the following equation (11) (step S7).
8).

Tcyl (N) = TiM × KTiB × Ktotal (N) (11) TiM is the basic fuel amount calculated in either of the steps S62 and S65. KTiB is a correction coefficient of the basic fuel injection amount TiM calculated in any of steps S70 and S73.

In step S79, the combustion chamber supply fuel amount TNET is calculated by the equation (4) shown in the first embodiment. In step S80, the TNET value calculated by the equation (4) is changed from the value 0. It is determined whether it is larger.

If the answer to step S80 is negative (NO), that is, if TNET.ltoreq.0, the fuel injection amount Tout is set to 0 (step S82), and the process proceeds to step S83. The answer to step S80 is affirmative (YES), that is, TNET> 0. In the case of, T is calculated by using the equation (5) shown in the first embodiment.
An out value is calculated (step S81), and step S83 is performed.
Proceed to.

Thus, in step S83, the ignition timing θIG is calculated according to the following equation (12), and the program ends.

ΘIG = (θIGM + θIGK) × KθIGB (12) Here, θIGM on the right side of the equation (12) is calculated in step S6.
2, the basic ignition timing calculated in S65.

ΘIGK is the water temperature T as in the first embodiment.
W, intake air temperature TA, engine operation mode, acceleration / deceleration state,
This is a correction value calculated according to various engine parameter signals such as an exhaust gas recirculation rate in the exhaust gas recirculation system.

KθIGB is a correction coefficient for the ignition timing θIG calculated in either of steps S71 and S74.

The ignition timing θIG of the ignition plug 23 of each cylinder of the engine 1 is controlled based on the θIG value calculated by the above equation (12).

As described above, also in the second embodiment of the present invention, the switching state of the exhaust gas passage by the BPV 18 and the selected valve are controlled by the programs of FIGS. 7 and 8 in the same manner as in the first embodiment. The fuel injection amount Tout and the ignition timing θIG can be appropriately obtained according to the timing, and the air-fuel ratio in the exhaust gas of the engine can be stabilized, and the emission characteristics can be improved.

[0097]

As described in detail above, according to the present invention, the exhaust
The adhering fuel amount and the holding
The amount of fuel left was changed, so each exhaust
Correct the influence of the amount of fuel attached to the intake pipe when the passage is switched.
Predict the air mixture that is supplied to the combustion chamber of the engine.
Precisely control the fuel ratio to the desired value to reduce emissions
Characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a control device for an internal combustion engine according to the present invention.

FIG. 2 shows the fuel consumption (Tout) according to the first embodiment.
And a flowchart (1/2) of a program for calculating an ignition timing (θIG).

FIG. 3 shows the fuel consumption (Tout) according to the first embodiment.
4 is a flowchart (2/2) of a program for calculating an ignition timing (θIG) and a program for calculating an ignition timing (θIG).

FIG. 4 is a Ti map and a θIG map for calculating a basic fuel injection amount TiM and a basic ignition timing θIGM according to the engine speed NE and the intake pipe absolute pressure PBA.

FIG. 5 is a flowchart of a program for calculating an intake pipe attached fuel amount (TWP (N)).

FIG. 6 is a diagram showing a table for calculating correction coefficients for a direct rate (A) and a carry-out rate (B).

FIG. 7 shows the fuel consumption (T) according to the second embodiment of the present invention.
(out) and a flowchart (1/2) of a program for calculating an ignition timing (θIG).

FIG. 8 shows the fuel consumption (T) according to the second embodiment of the present invention.
(out) and a flowchart (2/2) of a program for calculating an ignition timing (θIG).

FIG. 9 is a diagram showing a table for calculating correction coefficients for a direct rate (A) and a carry-out rate (B).

[Explanation of symbols]

1 internal combustion engine 5 ECU (basic control amount calculation means, change means , adhesion
Correction means ) 8 PBA sensor (operating state detecting means) 12 NE sensor (operating state detecting means) 14 Exhaust pipe (exhaust passage) Second catalyst device 18 Switching valve (switching means)

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F02D 9/04 F02D 9/04 C 43/00 301 43/00 301H 301T (56) References JP JP-A-3-229948 (JP, A) JP-A-4-50422 (JP, A) JP-A-63-272946 (JP, A) JP-A-61-53430 (JP, A) JP-A-3-229947 (JP) JP-A-61-283735 (JP, A) JP-A-62-159749 (JP, A) JP-A-3-156117 (JP, A) JP-A-4-31615 (JP, A) 3-210035 (JP, A) Japanese Utility Model Showa 63-132820 (JP, U) Japanese Utility Model Showa 52-135713 (JP, U)

Claims (1)

(57) [Claims] A first catalyst device disposed in an exhaust passage near an internal combustion engine; a second catalyst device disposed in the exhaust passage downstream of the first catalyst device; The first
Switching means for switching exhaust gas from the engine to one of the first catalyst device side and the bypass passage side ;
At least the engine speed and the load condition of the engine
Operating state detection for detecting the operating state of the engine including:
Based on the detection result of the operating state detecting means.
Basic calculation of basic control amount of fuel supply to engine
Control amount calculating means for injecting fuel into an intake pipe of the engine;
The amount of fuel deposited on the wall of the intake pipe,
The fuel adhering to the wall of the intake pipe evaporates and the engine
Taking into account the amount of fuel removed to the combustion chamber
An adhesion correction method for correcting the amount of fuel supplied to the engine
The control apparatus for an internal combustion engine equipped with a stage, with the
The arrival correction means is provided with the attachment according to the switching state of the switching means.
The attached fuel amount used by the arrival correction means and the carry-off
A control device for an internal combustion engine, comprising a change means for changing a fuel amount .