JPH0674081A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the emission characteristics of exhaust gas by adjusting an air-fuel ratio of air-fuel mixture to a desired air-fuel ratio even when an exhaust gas passage is switched. CONSTITUTION:A fundamental fuel injection time TiM and a fundamental ignition timing thetaIGM are calculated from a Ti map and a thetaIGM map set according to the set state of a switching valve and the set state of a valve timing at S3, S6, S10, and A13. Based on a thetaIGM value, an ignition timing thetaIG is decided and further, a fuel injection amount Tout is decided based on a TiM value as consideration is made on a fuel adhesion amount in an intake air pipe.

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 which controls the fuel supply amount and ignition timing according to the operating state of the engine.

[0002]

2. Description of the Related Art Conventionally, the exhaust passage of an internal combustion engine has two
It is known that individual catalyst devices (first and second catalyst devices) are arranged in series. According to this control device for an internal combustion engine, by disposing the first catalyst device having a relatively small volume in the vicinity of the engine and promoting activation of the catalyst device at the time of cold start, it is possible to efficiently perform at the time of cold start of the engine. It is possible to purify the exhaust gas. However, in this device, since the first catalyst device is arranged in the exhaust passage in the vicinity of the engine, the first catalyst device is exposed to high temperature exhaust gas for a long time after the engine is warmed up. Therefore, there is a drawback that the catalyst deteriorates severely and the life of the catalyst is short.

Therefore, in order to solve such a drawback, a bypass passage 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 device for an internal combustion engine, which has 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 prior art, the exhaust gas can be efficiently purified through the first catalyst device at the time of cold start, while the switching valve is moved to the bypass passage side after the engine is warmed up. By 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 connect the exhaust passage to the first catalyst device side, the exhaust pressure rises and the scavenging efficiency of the engine is increased. Engine intake efficiency (η
V) decreases, on the contrary, when the exhaust passage is switched to the bypass passage side, the exhaust pressure decreases and the scavenging efficiency of the engine increases, so that the intake efficiency (ηV) of the engine increases, but 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 stable and the emission characteristic is deteriorated.

The present invention has been made in order 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 and the emission characteristics of exhaust gas are improved. An object of the present invention is to provide a control device for an internal combustion engine capable of controlling

[0007]

In order to achieve the above object, the present invention provides a first catalyst device arranged in an exhaust passage near an internal combustion engine, and the exhaust gas downstream of the first catalyst device. A second catalyst device disposed in the passage, a bypass passage bypassing the first catalyst device, and exhaust gas from the engine is provided on one of the first catalyst device side and the bypass passage side. In a control device for an internal combustion engine, comprising: a switching means for switching to an operating state detecting means for detecting an operating state of the engine including at least an engine speed and a load state of the engine; and a detection result of the operating state detecting means. A basic control amount calculating means for calculating a basic control amount of at least one of a fuel supply amount and an ignition timing, wherein the basic control amount calculating means is responsive to the switching state of the switching means. That has a changing means for changing the present control amount is intended characterized.

[0008]

According to the above structure, the basic control amount calculated based on the operating state of the engine is changed according to the switching state of the switching means.

[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 the figure, reference numeral 1 denotes a DOHC in-line 4-cylinder internal combustion engine (hereinafter simply referred to as "engine") in which each cylinder is provided with an intake valve and an exhaust valve (not shown). In this engine 1, the valve timing (valve lift amount, valve opening period) of the intake valve and the exhaust valve is a high-speed valve timing (hereinafter, referred to as “HIV
/ T ") and a low speed valve timing (hereinafter referred to as" LOV / T ") suitable for a low speed rotation range.

Specifically, the valve timing switching mechanism 21 has an electromagnetic valve (not shown) for controlling valve timing switching, and the electromagnetic valve is an electronic control unit (hereinafter referred to as "ECU"). Connected to 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 according to the high / low of the hydraulic pressure. The hydraulic pressure of the valve timing switching mechanism 21 is
It is detected by the hydraulic 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 inside thereof.
Are arranged. Further, a throttle valve opening degree (θTH) sensor 4 is connected to the throttle valve 3 ′, and an ECU 5 outputs an electric signal according to the opening degree of the throttle valve 3 ′.
Supply to.

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 electrically connected to the ECU 5, and the EC
The valve opening time of fuel injection is controlled by the 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 the tip of the branch pipe 7. The PBA sensor 8 is electrically connected to the ECU 5, and the intake pipe 2
The absolute pressure PBA therein 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 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 water temperature (TW) sensor 10 composed of a thermistor or the like is attached to the peripheral wall of the cylinder filled with the cooling water of the cylinder block of the engine 1, and the engine cooling water temperature TW detected by the TW sensor 10 is converted into an electric signal. It is converted and supplied to the ECU 5.

Cylinder discrimination (CYL) is performed at a predetermined position around an unillustrated cam shaft or crank shaft of the engine 1.
A sensor 11 and an NE sensor 12 are attached respectively.

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 rotations of the crankshaft, and the NE signal is output.
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).
"DC signal pulse"), and these CYL signal pulse and TDC signal pulse are respectively supplied to the ECU 5.

The spark plug 23 of each cylinder of the engine 1 is
It is connected to the ECU 5, and the ignition timing is controlled by the ECU 5.

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
In No. 5, the sensor element is a zirconia solid electrolyte (ZrO ₂ )
The electromotive force has a characteristic that it rapidly changes before and after the stoichiometric air-fuel ratio, and the output signal is inverted from the lean signal to the rich signal or from the rich signal to the 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.
Supply to 5.

A first catalyst device 16 and a second catalyst device 17 are arranged in series in the exhaust pipe 14 downstream of the O 2 sensor 15.

The first catalyst device 16 is provided for activating the first catalyst device 16 promptly when the engine 1 is cold-started to improve the exhaust gas emission characteristics when the engine 1 is cold-started. The capacity is smaller than that of the second catalyst device 17. Then, by these first and second catalyst devices 16 and 17, HC and C in the exhaust gas are
The harmful components such as O and NOx are purified. Further, an exhaust communication passage (hereinafter referred to as “bypass passage”) 14a that bypasses the first catalyst device 16 side is provided so as to branch from the exhaust pipe 14 on the downstream side of the O 2 sensor 15. That is,
One end of the bypass passage 14a is connected to the exhaust pipe 14 on the upstream side of the first catalytic device 16 and the other end is connected to the first catalytic device 1.
6 is connected to the exhaust pipe 14 on the downstream side.

In the exhaust pipe 14 at the branch point between the upstream side of the first catalyst device 16 and the bypass passage 14a, the exhaust gas from the engine is supplied to the first catalyst device 16 side and the bypass passage 14.
A switching valve (bypass valve, hereinafter referred to as "BPV") 18 as switching means for switching to the a side is provided, and the BPV 18 is further provided with an electric actuator 19
(For example, a solenoid valve, a motor, etc.) are connected.

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 and driven by driving the electric actuator 19, so that 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 in operation (hereinafter referred to as "BPV OFF"), the BPV 18 is deenergized so that the exhaust gas from the engine is directed to the bypass passage 14a side, and when the electric actuator 19 is in operation (hereinafter referred to as "BPV OFF"). ,
"BPV ON") is urged to direct the exhaust gas to the first catalytic 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 side and the bypass passage 14a side, which of the first catalyst device 16 side and the bypass passage 14a side the exhaust gas passage of the BPV 18 is switched to. A BPV position detection sensor (hereinafter, referred to as “BP sensor”) 20 that detects the position is provided, and the BP sensor 20 detects the position of the BPV 18 and outputs the electric signal to the ECU 5. Also, BPV
Since 18 is driven by the electric actuator 19 by a signal from the ECU 5, the position detection of the BPV 18 may be replaced 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 if the operation of the PV 18 or the electric actuator 19 is delayed due to deterioration or the like.

The ECU 5 shapes the input signal waveforms from the various sensors described above, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, and the like, and a central processing unit. Circuit (hereinafter “CP
U ”), a storage means 5c including ROM and RAM for storing various calculation programs executed by the CPU 5b and various maps and calculation results 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 solenoid valve and the ignition plug 23.

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

First, in step S1, "BPV OF
If the answer is affirmative (YES), that is, if the exhaust gas passage is set to the bypass passage 14a side, the process proceeds to step S2, and the valve timing is HI V / T. Determine whether or not.

When the answer to step S2 is negative (NO), that is, when the valve timing is LO V / T, the routine proceeds to step S3, where Ti for LO V / T and BPV OFF is set.
Search the map and the θIG map to find the basic fuel injection amount T
iM and basic ignition timing θIGM are calculated.

Specifically, the Ti map and the θIG map are, as shown in FIGS. 4 (a) and 4 (b), the engine speed NE.
1 to NE20 and absolute pressure in intake pipe PBA1 to PBA17
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 are given. Is the Ti map and θI
It is read out by searching the G map or calculated by the interpolation calculation method.

In step S3, the basic fuel injection amount TiM
And basic ignition timing θIGM is LOV / T, BPV OF
From the Ti map and the θIG map for F, NE value and P
It is read out according to the detected value of BA value, and LOV / 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 adhered to the wall of the intake pipe by the fuel injected into the intake pipe of the engine and the amount of fuel adhered to the wall of the intake pipe evaporate and the combustion chamber of the engine is evaporated. Adhesion correction is performed in consideration of the amount of fuel taken away.

First, in step S4, LO V / T, B
The direct rate A and the take-away rate B for PV OFF are calculated. Here, the direct ratio A is the ratio of the fuel injected into the combustion chamber in the form of the fuel injected in a certain cycle, including the amount sucked by evaporation during the cycle, and the carry-out ratio B. Is the ratio of the fuel that has been attached to the wall of the intake pipe up to the previous time and that is sucked into the combustion chamber during the cycle due to evaporation or the like. The direct rate A and the take-away rate B are L set according to the engine water temperature TW and the intake pipe absolute pressure PBA.
The A map and the 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, the direct ratio A for LO V / T and BPV OFF is calculated by performing interpolation calculation as necessary.
And the carry-out rate B are calculated.

In the following step S5, LO V / T, B
The correction factors KA and KB of the direct rate A and the take-away rate B for PV OFF are calculated, and the process proceeds to step 16. The correction coefficients KA and KB are LO V / T and BP shown in FIG.
With KA table and KB table for V OFF,
It is set according to the engine speed NE. That is, the correction coefficient KA for the direct rate A and the correction coefficient KB for the take-away rate B are
It is set so that it increases as the NE value increases.

Here, when the engine speed NE rises, the correction factors KA and KB are increased because the intake flow velocity in the intake pipe is increased, so that the direct ratio A and the carry-out ratio B are apparently increased. Because.

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

That is, in step S6, H
From the Ti map and the θIG map for IV / T and BPV OFF, the basic fuel injection amount TiM and the basic ignition timing θIG
M is searched, then the A map and the B map (not shown) for HI V / T and BPV OFF are searched, and the direct rate A and the take-away rate B are calculated (step S7). Then, after this, the HIV / T, BPV shown in FIG.
By searching the KA table and the KB table for OFF, the correction coefficient KA for HI V / T, BPV OFF,
Calculate KB (step S8).

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 BPV ON, the process proceeds to step S9, and it is determined whether or not the valve timing is HI V / T.

The answer to step S9 is negative (NO), that is, L.
When it is in OV / T, similar to steps S6 to S8, the basic fuel injection amount TiM for LO V / T and BPV ON, the basic ignition timing θIGM, the direct ratio A and the take-away ratio B, and the correction coefficient. 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 calculated from the Ti map and θIG map for LO V / T and BPV ON which are substantially the same as 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 take-away rate B, and in step S12, the LO V / T, BPV shown in FIG.
Search KA table and KB table for ON, and
The correction factors KA and KB for OV / T and BPV ON are calculated.

If the answer to step S9 is affirmative (YES), HI is carried out in the same manner as 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 take-away rate B, and the correction coefficients KA and KB are calculated (steps S13 to S1).
5) and proceeds to step S16.

That is, in step S13, the basic fuel injection amount TiM and the basic ignition timing θIG are determined from the HI V / T, BPV ON Ti map and θIG map which are substantially the same as those in FIG.
M is searched, and in step S14, HI V / T, BP
By searching the A map and the B map (not shown) for V ON to calculate the direct rate A and the take-away rate B, step S
In No. 15, HI V / T, BPV O shown in FIG.
Search the KA and KB tables for N and
The correction coefficients KA and KB for V / T and BPV OFF are calculated.

The basic fuel injection amount TiM, the basic ignition timing θIGM, the direct rate A and the take-away rate B are all BP.
Since different tendencies are shown depending on ON / OFF of V18 and each valve timing, the Ti map, θIG map, A map, B map, KA table, and KB table are set corresponding to this tendency.

In this way, HI V / T, LO V / T,
The four types of Ti map, θIG map, A map and B map, which are different depending on the BPV OFF and BPV ON conditions, and the KA table and the KB table are provided because the intake efficiency of the engine generated by switching the exhaust gas passage ( This is to cope with fluctuations in ηV) and fluctuations in the flow velocity near the intake valve, which is one of the controlling factors of the fuel transport parameter caused by the valve timing of the intake valve, and pressure fluctuations caused thereby.

In the following step S16, the following equation (1),
According to (2), the corrected direct rate Ae and the corrected take-away rate Be
Is calculated, and (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 the starting mode. If the answer is affirmative (YES), the basic starting procedure is performed. 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 mode is not the starting mode, an addition correction term Ttota described later is obtained.
The required fuel amount Tcyl (N) for each cylinder not including 1 is calculated by the following equation (3) (step S19).

Tcyl (N) = TiM × Ktotal (N) (3) Here, (N) represents a cylinder number, and the parameter with this is calculated for each cylinder. TiM is the basic fuel amount calculated in any of the 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 operating 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, according to the following equation (4),
The combustion chamber supply fuel amount TNET, which is the fuel amount 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 (for example, acceleration increase correction) calculated based on engine operating parameter signals from various sensors. The term TACC, etc.). However, the invalid time TV described later is not included. TWP (N)
Is the intake pipe adhering fuel amount (predicted value) calculated by executing the flowchart of FIG. 6 to be described later, and (Be × TWP
(N)) corresponds to the amount of carry-away fuel that the fuel adhering to the intake pipe is carried away into the combustion chamber. Since it is not necessary to newly inject the amount of fuel to be carried away, 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, TNET≤0, the fuel injection amount Tout is set to 0. It proceeds to step S25. On the other hand, the answer in 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) where 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), the combustion chamber has (TN
An amount of fuel corresponding to ET (N) × KO2 + Be × TWP (N)) is supplied.

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

ΘIG = θIGM + θIGK (6) where θIGM is the above-mentioned steps S3, S6, S10,
It 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 operating mode, acceleration / deceleration state, exhaust gas recirculation ratio in the exhaust gas recirculation system. .

The ignition timing θIG of the spark 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 of FIGS. 2 and 3. Can be obtained, 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 take-away 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 switching state of the exhaust gas passage and switching state of the valve timing, it is possible to accurately predict the influence of the fuel amount adhering 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 flow chart of a program for calculating the intake pipe adhering fuel amount TWP (N). This program is for generating a crank angle pulse generated at every predetermined rotation (for example, 30 degrees) of the crankshaft. It is executed synchronously.

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

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

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 programs of FIGS. 2 and 3. Also, the first on the right side
The term corresponds to the amount of fuel that remained without being taken away this time among the fuel that was attached last time, and the second item on the right side corresponds to the amount of fuel that has newly attached to the intake pipe among the fuel that was injected this time. To do.

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

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

In step S37, it is determined whether or not the TWP (N) value is larger than the minute predetermined value TWPLG, and if the answer is affirmative (YES), that is, TWP (N)> TWPLG, the routine proceeds to step S40. When the answer to step S37 is negative (NO), that is, TWP (N) ≦ TWPLG, TWP (N) = 0 is set (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 intake pipe adhering fuel amount TWP (N) can be accurately calculated by the program of FIG. 6, and the calculated TWP (N) value can be calculated as shown in FIG.
By using the calculation of the fuel injection amount Tout in the program of FIG. 3, an appropriate amount of fuel in consideration of the amount of fuel adhering to the intake pipe and the amount of fuel carried away from the adhering fuel is supplied to the combustion chamber of each cylinder. be able to.

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

First, in step S61, it is determined whether or not the valve timing is "HI V / 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, and the basic fuel injection amount TiM for LO V / T and the basic ignition timing θIGM are calculated.

Basic fuel injection amount TiM for LO V / T,
The basic ignition timing θIGM is T for LO V / T set according to the engine speed NE and the intake pipe absolute pressure PBA.
The i map and the θ IG map (not shown) are searched 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 interpolation calculation as necessary.

Next, in step S63, the direct rate A and the take-away rate B for LO V / T are calculated. The direct rate A and the take-away rate B are the engine water temperature TW and the intake pipe absolute pressure P.
The LO V / T A map and 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 rate A and the take-away rate B for LO V / T are calculated by performing interpolation calculation as needed.

In the following step S64, the correction factors KA and KB of the direct ratio A and the carry-out ratio B for LO V / T are calculated, and the process proceeds to step S68. In step S64,
The correction coefficients KA and KB are LO V / shown in FIG.
The KA table and the KB table for T are searched according to the engine speed NE.

On the other hand, the answer in step S61 is affirmative (Y
In the case of (ES), the basic fuel injection amount TiM for HI V / T, the basic ignition timing θIGM, the direct rate A and the take-away rate B, and the correction coefficients KA and KB are calculated in the same manner as in steps S62 to S64. S65 to S67),
It proceeds to step S68.

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

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

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

In the following step S70, the 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 set according to the engine speed NE and the intake pipe absolute pressure PBA.
NETi and PB from the KTiB map (not shown) for
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 interpolation calculation as needed.

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

Here, the ignition timing θIG for BPV ON
The correction coefficient KθIGB is calculated from the NE value and the PBA from the KPVIGB map for BPV ON (not shown) set according to the engine speed NE and the intake pipe absolute pressure PBA.
It is read according to the detected value. At this time, the correction coefficient KθIGB of the ignition timing θIG for BPV ON is calculated by performing interpolation calculation as necessary.

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

Here, each correction coefficient K when BPV is OFF
AB, KBB, KTiB and KθIGB are each 1
The reason is that when BPV is OFF, the exhaust gas passage is on the exhaust bypass passage 14a side and the intake efficiency (η
This is because V) does not decrease, and therefore it is not necessary to correct.

In step S75, the following equation (9),
According to (10), the corrected direct rate Ae and the corrected take-away rate B
e is calculated, (1-Ae) and (1-Be) are further 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 the start mode, and if 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 present program is ended.

If the answer to step S77 is negative (NO), that is, if it is not the starting 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 any of steps S62 and S65. KTiB is a correction coefficient for the basic fuel injection amount TiM calculated in either 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, and in step S80, the TNET value calculated by the equation (4) is calculated from the value 0. It is determined whether it is large or not.

When the answer to step S80 is negative (NO), that is, TNET≤0, the fuel injection amount Tout is set to 0 (step S82), the process proceeds to step S83, and the answer to step S80 is affirmative (YES), that is, TNET> 0. Then, using the equation (5) shown in the first embodiment, T
The out value is calculated (step S81), and step S83
Proceed to.

As a result, in step S83, the ignition timing θIG is calculated by the following equation (12), and this program ends.

ΘIG = (θIGM + θIGK) × KθIGB (12) Here, θIGM on the right side of Expression (12) is calculated in step S6.
It is the basic ignition timing calculated in any one of S2 and S65.

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

KθIGB is a correction coefficient for the ignition timing θIG calculated in either step S71 or S74.

The ignition timing θIG of the spark 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 as in the case of the first embodiment. The fuel injection amount Tout and the ignition timing θIG can be appropriately determined according to the timing, 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 air-fuel ratio of the air-fuel mixture can be set to a desired value even if the exhaust passage is switched, and the emission characteristics of exhaust gas can be improved.

[Brief description of 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 is a flowchart (1/2) of a program for calculating a fuel injection amount (Tout) and an ignition timing (θIG) according to the first embodiment.

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

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 adhering fuel amount (TWP (N)).

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

FIG. 7 is a fuel injection amount (T according to a second embodiment of the present invention;
out) and the ignition timing (θIG).

FIG. 8 is a fuel injection amount (T according to a second embodiment of the present invention;
out) and an ignition timing (θIG) are a flowchart (2/2) of the program.

FIG. 9 is a diagram showing a table used to calculate a correction coefficient for a direct rate (A) and a carry-out rate (B).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 5 ECU (basic control amount calculating means, changing means) 8 PBA sensor (operating state detecting means) 12 NE sensor (operating state detecting means) 14 Exhaust pipe (exhaust passage) 14a Bypass passage 16 First catalyst device 17 Second catalyst device 18 Switching valve (switching means)

Claims (1)

[Claims] 1. A first catalyst device arranged in an exhaust passage near an internal combustion engine, and a second catalyst device arranged in the exhaust passage downstream of the first catalyst device, The first
A control device for an internal combustion engine, comprising: a bypass passage for bypassing the catalyst device of 1), and a switching means for switching the exhaust gas from the engine to one of the first catalyst device side and the bypass passage side. An operating state detecting means for detecting an operating state of the engine including a rotational speed and a load state of the engine,
A basic control amount calculation unit for calculating a basic control amount of at least one of a fuel supply amount and an ignition timing based on a detection result of the operating state detection unit, wherein the basic control amount calculation unit is a switching state of the switching unit. A control device for an internal combustion engine, comprising: changing means for changing the basic control amount according to the above.