JP2000345883A - Fuel injection quantity controller for internal combustion engine and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce all the hydrocarbon delivery quantity of total hydrocarbon(THC) of a catalyst non-active condition which purifying capacity of a catalyst is low by multiplying a correction coefficient by a fuel corrective amount according to the catalyst active condition to collect the fuel corrective amount by the fuel correcting means, in the case where the catalyst active condition is not complete and an acceleration opening is increased. SOLUTION: In the case where a catalyst active condition is a non active and an acceleration opening has being accelerated, a fuel corrective amount is reduced. For example, a correction coefficient 0 is multiplied by the fuel corrective amount to make zero, and a fuel sticking correction is inhibited. An acceleration opening is increased at a time t1, and it is decreased again at a time t2 after holding a constant time. The fuel corrective amount is reduced when a catalyst is activated, smaller than an air-fuel ratio 14.7 when fuel sticking correction is carried out at the time of acceleration, and then, fuel sticking correction is carried out. As a result, acceleration is suppressed. At the time of deceleration, a fuel injection amount Qout is reduced, a fuel sticking amount stuck on an inner wall of an intake pipe is suppressed, and rich of acceleration is reduced. It is thus possible to reduce a discharge quantity of THC when the catalyst is not activated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for an internal combustion engine and a control method therefor.

FIG. 13 shows a system configuration diagram of a conventional internal combustion engine (engine). In the figure, 101
Is an engine, 102 is an air cleaner, 103 is an intake passage, 104 is a throttle valve, 105 is a surge tank, 106 is an accelerator pedal, 107 is an accelerator opening detection sensor that detects the amount of depression of the accelerator pedal, 10
8, an electronic control unit; 109, a throttle actuator for opening and closing a throttle valve according to the value of an accelerator opening sensor; 110, a throttle opening sensor for detecting the opening of the throttle valve;
A crank angle sensor 112 for detecting a crank angle of 1; a cylinder identification sensor 112 for detecting which cylinder of the engine 101 the output signal of the crank angle sensor corresponds to;
Is a fuel injection valve, 114 is an ignition coil, 115 is an ignition coil drive unit that amplifies the ignition coil drive signal from the electronic control unit 108 to a high voltage and ignites the ignition coil,
116 is a catalytic converter as a catalyst, 117 is an exhaust gas temperature sensor for checking the activation state of the catalytic converter 116, and 118 is an oxygen concentration detecting sensor for detecting the oxygen concentration in the exhaust gas.

Next, the operation will be described. When the driver depresses the accelerator pedal 106, the electronic control unit 108
Detects the driver's accelerator opening from the accelerator opening detection sensor 107, and controls the throttle actuator 1 so that the opening of the throttle valve 104 becomes equal to the accelerator opening.
09 and the throttle opening sensor 110 are subjected to feedback control. When the throttle valve 104 is opened, air is drawn into the engine 101 through the air cleaner 102 and the suction passage 103. The electronic control unit 108 calculates the fuel injection amount from the intake air amount and the cycle of the crank angle signal from the crank angle sensor 111, and calculates the amount of fuel injection.
The fuel injection valve 113 of the cylinder to be injected is driven from the output of No. 2 to inject fuel. And the ignition coil drive unit 1
By outputting a signal to the ignition plug 15 and igniting the ignition plug 114, the injected fuel is ignited and the fuel is burned to drive the engine. Also, the electronic control unit 1
In a step 08, the oxygen concentration in the exhaust gas is detected by the oxygen concentration detection sensor 118, and the fuel amount is feedback-controlled. The gas discharged after driving the engine is purified and discharged by the catalytic converter 116.

FIG. 14 is a graph showing the relationship between the accelerator opening, the fuel injection amount, and the air-fuel ratio in a conventional fuel injection control device in time series. In FIG. 14, the horizontal axis of the graph represents time. FIG. 14A shows that the accelerator opening increases at a certain time t1 and the accelerator opening is kept constant for a certain period of time, and then decreased again at a time t2. I have. FIG. 14B shows the fuel injection amount when the accelerator opening is changed as shown in FIG. 14A, and FIG. 14C shows the air-fuel ratio at that time. As described above, the air-fuel ratio is shifted toward the lean side when the accelerator opening is increased (during acceleration) with respect to the target air-fuel ratio (14.7), and conversely, when the accelerator opening is decreased (deceleration). At the time), it changes to the rich side. This is because, when the accelerator opening increases, the amount of fuel that has adhered to the inner wall of the intake pipe leading to the combustion chamber of the engine among the fuel injected from the fuel injection valve 113 increases. This is because vaporization increases. That is, when the amount of fuel adhering to the intake pipe increases, the fuel supplied into the combustion chamber becomes
Since the fuel is less than the fuel injected from the fuel injection 13, the actual air-fuel ratio is on the lean side. On the other hand, when the amount of fuel adhering to the intake pipe increases, the amount of fuel supplied to the combustion chamber becomes larger than the amount of fuel injected from the injection valve 113, so that the actual air-fuel ratio becomes richer.

FIG. 15 is a conceptual diagram showing the adhesion of fuel on the inner wall surface of the intake pipe 307. In the figure, 301 is a fuel injection valve, 302 is a surge tank, 307 is an intake pipe, 303 is fuel attached to the intake pipe 307, 304 is an intake valve, 3
05 is a piston, 306 is a cylinder. Cylinder 3
Reference numeral 06 denotes a combustion chamber, and the fuel amount Q sucked into the cylinder 306 is the fuel amount Q injected from the fuel injection valve 301.
The fuel Qf attached to the intake pipe 307 at the out or the fuel Qw vaporized from the intake pipe 307 is considered. Q = Qout−Qf + Qw where Q: fuel amount to be taken into the cylinder Qout: fuel amount injected from the fuel injection valve Qf: fuel amount adhering to the intake pipe Qw: intake pipe It is the amount of fuel that evaporates more. As described above, the fuel amount Qout injected from the fuel injection valve 301 is not directly sucked into the cylinder 306. Therefore, during the transient operation in which the opening degree of the throttle valve 104 changes and the intake pressure in the intake pipe 307 changes. , Fuel amount Qf adhering to intake pipe 307 and intake pipe 3
Since the fuel amount Qw vaporized from 07 changes transiently,
As described above, the actual air-fuel ratio fluctuates.

In order to suppress such a phenomenon that the air-fuel ratio fluctuates during acceleration / deceleration, which is a transient operation in which the accelerator opening changes, the target air-fuel ratio is set so that the actual air-fuel ratio becomes the target air-fuel ratio during acceleration / deceleration. Conventionally, a fuel adhesion correction for correcting the fuel amount with respect to the fuel amount corresponding to the above has been performed.

FIG. 16 is a graph showing, in a time series, the relationship between the accelerator opening, the fuel injection amount, and the air-fuel ratio when the fuel adhesion correction for correcting the fuel amount in consideration of the fuel adhering to the inner wall surface of the intake pipe is performed. is there. In the figure, the horizontal axis of the graph represents time, and FIG. 16A shows that the accelerator opening increases at a certain time t1, keeps the accelerator opening constant for a certain period of time, and then decreases again at t2. . FIG. 16B shows the fuel injection amount when the accelerator opening is changed as shown in FIG. 16A, and FIG. 16C shows the air-fuel ratio at that time.
When the fuel adhesion correction is performed in this manner, the air-fuel ratio is maintained at 14.7 as shown in FIG.

As described above, in the conventional fuel adhesion correction, since a large amount of fuel adheres to the inner wall surface of the intake pipe during acceleration, the amount of fuel to be injected is increased, and a large amount of fuel adheres to the inner wall surface of the intake pipe during deceleration. Therefore, the injection is performed so as to reduce the amount of fuel to be injected. Accordingly, when the fuel adhesion correction is performed, the air-fuel ratio fluctuates toward the rich side when the accelerator opening increases and toward the lean side when the accelerator opening decreases as compared to when the correction is not performed.

[0009]

Here, when considering the exhaust gas generated after the fuel supplied to the combustion chamber is burned, if the catalyst for purifying the exhaust gas is completely activated, the exhaust gas is converted to the exhaust gas. The contained THC (total hydrocarbon) emissions are not increased by the catalyst. However, if the fuel adhesion correction is performed in the catalyst inactive state, the air-fuel ratio at the time of increasing the accelerator opening becomes richer.
There is a problem that the amount of HC emission increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem, and a fuel injection amount control device for an internal combustion engine for reducing the amount of THC emission in a catalyst inactive state having a low catalyst purification ability and its control. Is to provide a way.

[0011]

According to the present invention, there is provided a fuel injection amount control device for an internal combustion engine, comprising: accelerator opening detecting means for detecting an accelerator opening which is a stepping amount of a driver's accelerator; and a predetermined air-fuel ratio. A fuel injection amount calculating means for calculating a fuel injection amount based on at least an accelerator opening degree, a fuel correction amount storing means for storing a fuel correction amount in consideration of a fuel amount adhering to an intake pipe inner wall surface, and a fuel injection amount. A fuel correction means for correcting the fuel injection amount by adding or subtracting a fuel correction amount, a catalyst activity detection means for detecting an active state of a catalyst for purifying exhaust gas, and a correction based on an active state of the catalyst. Correction coefficient storage means for storing a coefficient, wherein when the catalyst activation state is not the complete activation state and the accelerator opening increases, the fuel correction means By correcting the fuel correction amount by multiplying the correction coefficient to a positive amount, it is intended to reduce the THC emissions.

Further, in the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient is a predetermined constant value.

Further, in the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient increases according to the degree of the catalyst activity.

Further, in the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient changes according to the magnitude of the accelerator opening.

Further, in the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient increases stepwise or continuously from a predetermined value including 0 according to the magnitude of the accelerator opening.

Further, the fuel injection amount control device for an internal combustion engine according to the present invention includes an accelerator speed calculating means for calculating an accelerator depression speed which is a time change of the accelerator opening from the accelerator opening, and the correction coefficient is determined by the accelerator depression. It changes according to the speed.

Further, in the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient is increased stepwise or continuously from a predetermined value including 0 according to the magnitude of the accelerator pedal depression speed.

Further, according to a fuel injection amount control method for an internal combustion engine according to the present invention, a catalyst activity detecting step for detecting an active state of a catalyst for purifying exhaust gas, and an accelerator opening which is a driver's accelerator depression amount are determined. An accelerator opening detection step for detecting, a fuel injection amount calculating step for calculating a fuel injection amount based on at least the accelerator opening so as to obtain a predetermined air-fuel ratio, and a correction coefficient based on an activation state of the catalyst. A correction coefficient calculating step of correcting the fuel correction amount by multiplying the fuel correction amount by a correction coefficient according to the catalyst activation state when the catalyst activation state is not the complete activation state and the accelerator opening is increased. And T
This is to reduce the amount of HC emission.

Also, the fuel injection amount control method for an internal combustion engine according to the present invention includes an accelerator speed calculating step of calculating an accelerator stepping speed which is a time change of the accelerator opening from the accelerator opening, wherein the correction coefficient is determined by the accelerator stepping. It changes according to the speed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 An embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows a configuration of an engine system including a fuel injection control device for an internal combustion engine according to the present invention. This is almost the same as FIG. 12, but differs in the control content depending on the components constituting the electronic control unit 200. In the following drawings, the same or equivalent members and portions as those in FIG. 12 are denoted by the same reference numerals, and redundant description will be omitted.

An accelerator opening detecting sensor 107 for detecting the amount of depression of the accelerator pedal 106 by the driver constitutes an accelerator opening detecting means. Electronic control unit 208 mainly composed of CPU 203 (central processing unit)
Then, for example, the fuel injection amount Qout injected from the fuel injection valve 113 so as to reach a predetermined target air-fuel ratio of 14.7.
The fuel injection amount calculating means for calculating the fuel injection amount based on at least the accelerator opening, the fuel correction amount storing means storing the fuel correction amount Q 'in consideration of the fuel amount adhering to the inner wall surface of the intake pipe, the fuel injection amount Qout A fuel correction means for correcting the fuel injection amount Qout by adding or subtracting a fuel correction amount Q ′, a catalyst activity detecting means for detecting an active state of a catalyst for purifying exhaust gas, and a catalyst activity based on the activity of the catalyst. There is provided a correction coefficient storage means for storing a correction coefficient. For example, the electronic control unit 208 includes the AD converter 20
1 is provided, and converts an analog signal of the accelerator opening from the accelerator opening detection sensor 107 into a digital signal. Also,
A ROM 204 is provided, and stores a fuel correction amount in consideration of a fuel amount adhering to the inner wall surface of the intake pipe and a correction coefficient based on the activity of the catalyst. Further, an input / output interface 202 is provided, through which an output signal from the crank angle sensor 112 is input to the CPU 203,
The PU 203 detects whether or not the engine 101 is in the starting state, and determines the operating time of the engine 101 after the engine is started by the clock pulse C from the clock generation circuit 206.
The PU 203 calculates a catalytic converter 116 which is a catalyst for purifying exhaust gas based on the operation time of the engine 101.
Activated state is detected.

Next, the operation will be described. First, a method for detecting the active state of the catalytic converter 116 as a catalyst will be described with reference to FIG. FIG. 10 is a graph that determines the relationship between the elapsed time of the state in which the engine 101 has been started and continues to operate and the catalyst activation state. That is, FIG.
Represents the elapse of the engine operating time from the start of the engine. The catalyst is deactivated in a state where the catalyst is not completely activated from the start of the engine until a certain time t, and the catalyst is completely activated after the time t. The catalyst activity is in the state of being in the state.

FIG. 6 is a flowchart for executing the fuel injection control according to the embodiment of the present invention, which is executed by the CPU 203 for each fuel injection of each cylinder. In step S901, the activation state of the catalyst is determined. If the catalyst is inactive, that is, if t time has not elapsed since the start of the engine, the process proceeds to step S902. Step S90
In step 2, it is determined whether the accelerator opening is increasing (accelerating). If the accelerator opening is increasing, the fuel correction amount Q 'is decreased in step S904. For example, the fuel correction amount Q ′ is multiplied by a correction coefficient 0 to set the fuel correction amount Q ′ to 0.
And fuel adhesion correction is prohibited. Instead of using a value greater than 0 and less than 1 as the correction coefficient to prohibit the fuel adhesion correction, the fuel correction amount Q ′ may be reduced compared to when the catalyst is active.

If the accelerator opening has not increased, the flow advances to step S903 to determine whether the accelerator opening is decreasing (during deceleration). If the accelerator opening is decreasing, in step S905, the fuel adhesion correction (Qo
ut = Qout−Q ′).

FIG. 2 is a graph showing the relationship between the accelerator opening (APS), the fuel injection amount (Qout), and the air-fuel ratio (A / F) in this embodiment in a time series. In the figure, the horizontal axis of the graph represents time, and FIG.
In (a), the accelerator opening increases at a certain time t1, the accelerator opening is kept the same for a certain time, and then decreases again at t2. FIG. 2B shows the fuel injection amount when the accelerator opening is changed as shown in FIG. 2A, and FIG. 2C shows the air-fuel ratio at that time. As shown in FIG. 2 (c), the air-fuel ratio when the conventional fuel adhesion correction is performed during acceleration is 14.7.
It can be seen that the enrichment caused by performing the fuel adhesion correction is more suppressed in the embodiment of the present invention in which the fuel correction amount Q ′ is reduced than when the catalyst is active. Also, during deceleration, the fuel injection amount Qout is reduced, and the intake pipe 30
The amount of fuel adhering to the inner wall of the fuel cell 7 is suppressed, and the enrichment during the next acceleration is reduced. Since the air-fuel ratio is prevented from being enriched, the amount of THC emission when the catalyst is inactive is reduced.

In the above-described embodiment, the elapsed time from the start of the engine is used as means for detecting the activation state of the catalyst. However, the integrated amount of the fuel injection amount from the start of the engine is equal to the predetermined integrated amount Qtotal. Up to the total amount Qtotal may be the catalyst activity.
Alternatively, depending on the travel distance from the start of the engine, the catalyst may be deactivated up to a predetermined travel distance L, and the catalyst activation may be performed over the travel distance L. Alternatively, the temperature of the catalytic converter 116 may be directly detected, and the catalyst may be deactivated when the temperature of the catalytic converter 116 is equal to or lower than a predetermined temperature TC, and the catalyst may be activated when the temperature is equal to or higher than the temperature TC. The catalyst may be deactivated when the engine cooling water temperature is equal to or lower than a predetermined temperature TR, and may be set to be catalytically active when the temperature is equal to or higher than the temperature TR. The catalyst may be deactivated when the exhaust temperature of the exhaust temperature sensor 117 is lower than the predetermined temperature TE, and the catalyst may be activated when the exhaust temperature is higher than the exhaust temperature TE. Further, the catalyst activation state may be detected by combining the above-described elapsed time from the engine start, integration of the fuel injection amount from the engine start, travel distance from the engine start, catalyst temperature, engine cooling water temperature, and exhaust temperature. .

Embodiment 2 FIG. FIG. 7 is a flowchart for executing the fuel injection control according to another embodiment of the present invention, which is executed by the CPU 203 for each fuel injection of each cylinder. FIG. 7 differs from FIG. 6 in that the correction coefficient is changed and the fuel correction amount Q ′ is changed depending on the degree of the active state of the catalyst even when the catalyst is in an inactive state.

First, a method of detecting the degree of activation of the catalytic converter 116, which is the degree of activation of the catalytic converter 116, will be described with reference to FIG. FIG. 11 is a graph that determines the relationship between the elapsed time and the catalyst activity in a state where the engine 101 is started and continues to operate. That is, FIG. 11 shows the lapse of the engine operating time, in which the catalyst is inactive in a state where the catalyst is not completely activated from the start of the engine until a certain time t, and the catalyst is completely activated after the time t. The catalyst activity Ac is a function of time t when the catalyst is inactive, that is, when the catalyst is inactive, that is, when the engine operation time has not reached time t. %, The catalyst activity Ac at the time t is defined as 100%, and the catalyst activity Ac at each time is set to gradually increase with the elapsed time after starting the engine.

Returning to FIG. 7, in step S1001,
The activation state of the catalyst is determined by the method described in FIG. The catalyst is inactive, that is, the catalyst activity Ac is 100%
If not, the process proceeds to step S1002. Step S1
In step 002, it is determined whether the accelerator opening is increasing (accelerating). If the accelerator opening is increasing, in step S1004, the correction coefficient f (C
t), the fuel correction amount Q ′ is corrected, and the fuel injection amount Q
The corrected fuel correction amount Q ′ is added to out.

Here, the correction coefficient f (Ct) is a predetermined value based on the catalyst activity Ac and is stored in the correction coefficient storage means RO.
It is stored in M204. As the catalyst activity Ac increases, the correction coefficient f (Ct) also increases stepwise within a range of 0 or more and 1 or less. Other points are the same as those in FIG.

FIG. 3 shows an accelerator opening (APS), a fuel injection amount (Qout), and an air-fuel ratio (A) in this embodiment.
/ F) is a graph showing the relationship in chronological order. In the figure, the horizontal axis of the graph represents time, and FIG.
At a certain time t1, the accelerator opening increases, and after keeping the accelerator opening the same for a certain period of time, the accelerator opening is decreased again at t2, and this operation is repeated. At a certain time t (2n-1), the accelerator opening increases, After keeping the accelerator opening constant for a certain period of time, t
In (2n), it is reduced again. FIG. 3B shows the fuel injection amount when the accelerator opening is changed as shown in FIG. 3A, and FIG. 3C shows the air-fuel ratio at that time. FIG.
As shown in (c), at the time of the first acceleration 601, the air-fuel ratio becomes equal to that of the above-described embodiment, but thereafter the air-fuel ratio gradually approaches the ideal air-fuel ratio of 14.7. The fuel correction amount approaches the fuel correction amount in the fully activated state as the catalyst approaches the fully activated state, and the air-fuel ratio is enriched, so that the THC emission is reduced in the same manner as in the above-described embodiment. And accelerated driving performance is improved.

In the above-described embodiment, as a means for detecting the catalyst activity Ac, the time from the start of the engine is used. However, the integrated amount of the fuel injection amount from the start of the engine or the travel distance from the start of the engine is different. The catalyst activity Ac may be set so as to increase as it increases.
In addition, as shown in FIG. 12, the catalyst activity Ac may be determined to increase as the temperature of the catalytic converter 116 increases. Further, the catalyst activity Ac may be set so as to increase as the cooling water temperature of the engine or the exhaust gas temperature of the exhaust gas temperature sensor 117 becomes higher. Further, the catalyst activity Ac may be detected by combining the above-described time from the engine start, integration of the fuel injection amount from the engine start, travel distance from the engine start, catalyst temperature, engine cooling water temperature, and exhaust gas temperature. . Further, the correction coefficient f (Ct) according to the catalyst activity is not limited to a value that increases stepwise, but may be continuously increased in a range of 0 to 1 in proportion to the catalyst activity Ac. Good.

Embodiment 3 FIG. 8 is a flowchart for executing the fuel injection control according to another embodiment of the present invention, which is executed by the CPU 203 for each fuel injection of each cylinder. FIG. 8 is different from FIG. 6 in that the correction coefficient is changed in accordance with the accelerator opening and the fuel correction amount Q ′ is changed in the inactive state of the catalyst.

In the figure, the difference from FIG. 6 is step S1104, and the other steps are the same as in FIG. In step S1104, the fuel correction amount Q 'is corrected by multiplying the fuel correction amount Q' by a correction coefficient f (TH) corresponding to the accelerator opening, and the corrected fuel correction amount Q 'is calculated for the fuel injection amount Qout. Is added.

Here, as the correction coefficient f (TH), a predetermined value corresponding to the accelerator opening is stored in the ROM 2 as the correction coefficient storage means.
04. The correction coefficient f (TH) gradually increases in the range of 0 or more and 1 or less as the accelerator opening increases. For example, when the accelerator opening is larger than the first predetermined value AC1, the correction coefficient f (TH) is set to 1;
If the second predetermined value AC2 is smaller than the first predetermined value AC1, the correction coefficient f (TH) is set to 0. If the second predetermined value AC2 is between the first predetermined value AC1 and the second predetermined value AC2, the correction coefficient f (TH) is set. (TH) is set to 0.5.

FIG. 4 shows an accelerator opening (APS), a fuel injection amount (Qout), and an air-fuel ratio (A) in this embodiment.
/ F) is a graph showing the relationship in chronological order. In the figure, the horizontal axis of the graph represents time, and FIG.
At a certain time t1, the accelerator opening increases, and after keeping the accelerator opening equal to or more than the first predetermined value AC1 for a certain period of time, t
2, the accelerator opening increases at a certain time t3, the accelerator opening is kept at the same value for a certain period of time below the second predetermined value AC2, and then decreased again at t4.
At a certain time t5, the accelerator opening increases, the accelerator opening is kept the same between the first predetermined value AC1 and the second predetermined value AC2 for a certain period of time, and then reduced again at t6. FIG.
4B shows the fuel injection amount when the accelerator opening is changed as shown in FIG. 4A, and FIG. 4C shows the air-fuel ratio at that time.

In FIG. 4B, when the accelerator opening is equal to or more than the first predetermined value AC1 during acceleration, the same fuel adhesion correction as in the catalyst activation state is performed, and the accelerator opening is changed to the second opening.
Is equal to or less than the predetermined value AC2, the fuel correction amount Q ′ is set to 0,
Fuel adhesion correction is prohibited. In addition, the accelerator opening changes the accelerator opening between a first predetermined value AC1 and a second predetermined value AC2.
In the meantime, the fuel adhesion amount correction in which the fuel correction amount Q ′ is reduced is performed. As shown in FIG. 4 (c), in this embodiment, when the accelerator opening is large, the operation is at a high load, so that the traveling performance is improved by shifting the air-fuel ratio to the rich side. On the other hand, when the accelerator opening is small during acceleration, the fuel correction amount Q ′ is reduced, and the THC emission amount is reduced.

Note that a correction coefficient f corresponding to the accelerator opening is
(TH) is not limited to a value that increases stepwise, and may increase continuously in the range of 0 to 1 in proportion to the catalyst activity Ac.

Embodiment 4 FIG. 9 is a flowchart for executing the fuel injection control according to another embodiment of the present invention, which is executed by the CPU 203 for each fuel injection of each cylinder. FIG. 9 differs from FIG. 6 in that the correction coefficient is changed and the fuel correction amount Q ′ is changed in accordance with the accelerator depression speed, which is a time change of the accelerator opening, when the catalyst is in an inactive state.

In the figure, the difference from FIG. 6 is step S1204, and the other steps are the same as in FIG. In step S1204, the fuel correction amount Q 'is corrected by multiplying the fuel correction amount Q' by a correction coefficient f (Vth) corresponding to the accelerator pedal depression speed, and the corrected fuel correction amount Q 'is corrected for the fuel injection amount Qout. Is added.

Here, as the correction coefficient f (Vth), the CPU 203 calculates the accelerator depression speed from the accelerator opening, and a predetermined value corresponding to the accelerator depression speed is stored in the ROM 204 as the correction coefficient storage means. The correction coefficient f (Vth) gradually increases in the range of 0 or more and 1 or less as the accelerator depression speed increases.
For example, when the accelerator depression speed is the first predetermined value ACV1
If larger, the correction coefficient f (Vth) is set to 1 and the first
Is smaller than a second predetermined value ACV2 that is smaller than the predetermined value ACV1, the correction coefficient f (Vth) is set to 0, and if it is between the first predetermined value ACV1 and the second predetermined value ACV2, the correction coefficient f (Vth) is set. ) Is set to 0.5.

FIG. 5 shows an accelerator opening (APS), a fuel injection amount (Qout), and an air-fuel ratio (A) in this embodiment.
/ F) is a graph showing the relationship in chronological order. In the figure, the horizontal axis of the graph represents time, and FIG.
At a certain time t1, the accelerator pedal 106 is rapidly depressed, the accelerator opening increases at an accelerator depressing speed equal to or higher than the first predetermined value ACV1, and the accelerator opening is kept the same for a certain period of time, and then reduced at t2. Next, at a certain time t
At 3, the accelerator opening increases at the accelerator depression speed equal to or less than the second predetermined value ACV2, and the accelerator opening is kept the same for a certain period of time, and then decreased at t4. Further, at a certain time t5, the first predetermined value ACV1 and the second predetermined value ACV
The accelerator opening increases at the accelerator depressing speed between 2 and 2, and after keeping the accelerator opening constant for a certain period of time, t6
It is decreasing by. FIG. 5 (b) shows the fuel injection amount when the accelerator opening is changed as shown in FIG. 5 (a) due to a difference in accelerator pedal depression speed, and FIG. 5 (c) shows the air-fuel ratio at that time.

In FIG. 5 (b), when the accelerator opening increases at the accelerator depression speed equal to or higher than the first predetermined value ACV1 during acceleration, the same fuel adhesion correction as in the catalyst active state is performed. When the accelerator opening increases slowly at an accelerator depression speed equal to or less than the second predetermined value ACV2, the fuel correction amount Q 'is set to 0, and the fuel adhesion correction is prohibited.
Further, when the accelerator opening increases at the accelerator depression speed between the first predetermined value ACV1 and the second predetermined value ACV2, the fuel adhesion correction is performed with the fuel correction amount Q ′ reduced.

As shown in FIG. 5C, in this embodiment, when the accelerator pedal is depressed at a high speed, the vehicle is rapidly accelerated. Therefore, the traveling performance is improved by changing the air-fuel ratio to the rich side. On the other hand, when the accelerator stepping speed is low during acceleration, the fuel correction amount Q ′ is reduced, and the THC emission amount is reduced.

It should be noted that the correction coefficient f (Vth) corresponding to the accelerator pedal depression speed is not limited to a value that increases stepwise, but increases continuously in the range of 0 to 1 in proportion to the catalyst activity Ac. May be.

Embodiment 5 FIG. In the above-described first to fourth embodiments, the fuel correction amount Q ′ is set by using any one of the activation state of the catalyst, the accelerator opening, and the accelerator depression speed as a parameter.
Is corrected, and the fuel correction amount Q ′ when the accelerator opening is increased is reduced with respect to the fully activated state of the catalyst, but these parameters may be combined. For example, a two-dimensional or three-dimensional map in which the catalyst activity, the accelerator opening, and the accelerator depression speed are set on each axis is provided in the ROM 204 or the RAM 205, and 0 or more corresponding to the values of the catalyst activity, the accelerator opening, and the accelerator depression speed are provided. 1
The following one correction coefficient f (Ct, TH, Vth) is obtained. In this case, both the acceleration running performance and the THC emission reduction effect can be improved in a well-balanced manner.

[0047]

According to the fuel injection amount control apparatus for an internal combustion engine according to the present invention, the accelerator opening detecting means for detecting the accelerator opening, which is the amount of depression of the accelerator by the driver, is provided so as to achieve a predetermined air-fuel ratio. A fuel injection amount calculating unit that calculates a fuel injection amount based on at least an accelerator opening degree; a fuel correction amount storing unit that stores a fuel correction amount in consideration of a fuel amount attached to an intake pipe inner wall surface; A fuel correction means for correcting the fuel injection amount by adding or subtracting the fuel correction amount, a catalyst activity detection means for detecting an active state of the catalyst for purifying exhaust gas, and a correction coefficient based on the active state of the catalyst. And a correction coefficient storage means for storing, wherein when the catalyst activation state is not the full activation state and the accelerator opening increases, the fuel correction means adjusts the fuel correction amount according to the catalyst activation state. Since multiplying a positive coefficient for correcting the fuel correction amount, thereby reducing the THC emissions low catalytic inactive capable of purifying exhaust gas.

Further, according to the fuel injection amount control apparatus for an internal combustion engine according to the present invention, since the correction coefficient is a predetermined constant value, it is possible to reduce the amount of THC emission when the catalyst is in an inactive state with a simple configuration.

Further, according to the fuel injection amount control apparatus for an internal combustion engine according to the present invention, the correction coefficient increases in accordance with the degree of catalyst activity. The traveling performance during acceleration can be improved while reducing the amount.

Further, according to the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient changes according to the magnitude of the accelerator opening. The driving performance during acceleration can be improved while reducing the THC emission while responding to the driver's intention that appears in the above.

Further, according to the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient increases stepwise or continuously from a predetermined value including 0 in accordance with the degree of accelerator opening. In high load operation with a large accelerator opening, the driving performance is improved, and when the accelerator opening is small, T
The amount of HC emission is reduced, and the traveling performance during acceleration can be improved while reducing the amount of THC emission.

Further, according to the fuel injection amount control device for an internal combustion engine according to the present invention, there is provided an accelerator speed calculating means for calculating an accelerator depression speed which is a time change of the accelerator opening from the accelerator opening, and the correction coefficient is determined by the accelerator coefficient. It changes according to the stepping speed, so while reducing THC emissions,
Drivability according to the accelerator depression speed can be improved.

Further, according to the fuel injection amount control device for an internal combustion engine according to the present invention, the correction coefficient increases stepwise or continuously from a predetermined value including 0 according to the magnitude of the accelerator pedal depression speed. When the accelerator stepping speed is high, the traveling performance at the time of sudden acceleration can be improved, and when the accelerator stepping speed is low, the THC emission can be reduced.

Further, according to the fuel injection amount control method for an internal combustion engine according to the present invention, a catalyst activity detecting step of detecting an active state of a catalyst for purifying exhaust gas, and an accelerator opening which is a driver's accelerator pedal depression amount. An accelerator opening detecting step of detecting the degree of fuel injection, a fuel injection amount calculating step of calculating a fuel injection amount based on at least the accelerator opening so that a predetermined air-fuel ratio is obtained, and a correction coefficient based on an activation state of the catalyst. A correction coefficient calculating step of calculating the fuel correction amount by multiplying the fuel correction amount by a correction coefficient according to the catalyst activation state when the catalyst activation state is not the complete activation state and the accelerator opening increases. Since the correction step is provided, it is possible to reduce the THC emission in the catalyst inactive state having a low ability to purify the exhaust gas.

Further, according to the fuel injection amount control method for an internal combustion engine according to the present invention, there is provided an accelerator speed calculating step of calculating an accelerator depression speed which is a time change of the accelerator opening from the accelerator opening, and the correction coefficient is Since it changes according to the accelerator pedal depression speed, it is possible to improve the traveling performance according to the accelerator pedal depression speed while reducing the THC emission.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an engine including a fuel injection control device according to an embodiment of the present invention.

FIG. 2 is a time-series graph showing a relationship between an accelerator opening, a fuel injection amount, and an air-fuel ratio in the fuel injection control operation according to the first embodiment of the present invention.

FIG. 3 is a graph showing a time-series relationship among an accelerator opening, a fuel injection amount, an air-fuel ratio, and a catalyst activity in a fuel injection control operation according to the second embodiment of the present invention.

FIG. 4 is a graph showing a time-series relationship between an accelerator opening, a fuel injection amount, and an air-fuel ratio in a fuel injection control operation according to a third embodiment of the present invention.

FIG. 5 is a graph showing a time-series relationship between an accelerator opening, a fuel injection amount, and an air-fuel ratio in a fuel injection control operation according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart showing a fuel injection control operation showing the operation of the first embodiment of the present invention.

FIG. 7 is a flowchart showing a fuel injection control operation showing an operation of the second embodiment of the present invention.

FIG. 8 is a flowchart showing a fuel injection control operation showing an operation of the third embodiment of the present invention.

FIG. 9 is a flowchart showing a fuel injection control operation showing an operation of the fourth embodiment of the present invention.

FIG. 10 is a graph illustrating a method for detecting a catalyst activation state according to the first embodiment of the present invention.

FIG. 11 is a graph illustrating a method for detecting catalyst activity according to Embodiment 2 of the present invention.

FIG. 12 is a graph illustrating a method for detecting catalyst activity in a modification of the second embodiment of the present invention.

FIG. 13 is a system configuration diagram of a conventional engine.

FIG. 14 is a graph showing, in a time series, a relationship among an accelerator opening, a fuel injection amount, and an air-fuel ratio in a conventional fuel injection control device.

FIG. 15 is a conceptual diagram showing fuel adhesion on the inner wall surface of an intake pipe in a conventional fuel injection control device.

FIG. 16 is a graph showing a time-series relationship between an accelerator opening, a fuel injection amount, and an air-fuel ratio when a conventional fuel adhesion correction is performed in a conventional fuel injection control device.

[Explanation of symbols]

107 accelerator opening sensor (accelerator opening detecting means), 116 catalytic converter (catalyst), 117 exhaust temperature sensor (catalytic activity detecting means), 200 electronic control unit (fuel injection amount calculating means, fuel correcting means, catalyst activity) Detecting means, accelerator speed calculating means), 203 CP
U (fuel injection amount calculating means, fuel correcting means, catalyst activity detecting means, accelerator speed calculating means), 204 ROM (fuel correcting amount storing means, correction coefficient storing means), 206 clock pulse generating circuit (catalytic activity detecting means) ), 307
Intake pipe, Q 'fuel correction amount, Qout fuel injection amount, f
(Ct), f (TH), f (Vth) correction coefficient.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02D 45/00364 F02D 45/00 364N (72) Inventor Tadahiro Higashi 2-6 Otemachi, Chiyoda-ku, Tokyo No. 2 Mitsubishi Electric Engineering Co., Ltd. F term (reference) 3G084 BA09 BA13 CA01 CA04 CA06 DA10 DA25 DA27 EA07 EA11 EC03 FA10 FA13 FA20 FA27 FA36 3G301 JA26 JB09 KA01 KA09 KA12 KA16 KA16 MA01 MA11 NA04 NA08 NE06 NE13 NE23 PB03Z PB10Z PF03Z PF04Z PF16Z

Claims (9)

[Claims] 1. An accelerator opening detecting means for detecting an accelerator opening which is a driver's accelerator depression amount, and a fuel injection calculating a fuel injection amount based on at least the accelerator opening so as to attain a predetermined air-fuel ratio. An amount calculating unit; a fuel correction amount storing unit storing a fuel correction amount in consideration of an amount of fuel adhering to the inner wall surface of the intake pipe; and adding or subtracting the fuel correction amount to or from the fuel injection amount to obtain the fuel injection amount. Fuel correction means for correcting the catalyst, catalyst activity detection means for detecting an active state of a catalyst for purifying exhaust gas, and correction coefficient storage means for storing a correction coefficient based on the active state of the catalyst. When the catalyst activation state is not the full activation state and the accelerator opening increases, the fuel correction means adjusts the fuel correction amount to the fuel correction amount according to the catalyst activation state. The fuel correction amount is corrected by multiplying
Fuel injection amount control apparatus for internal combustion engine, characterized in that emission amount is reduced 2. The fuel injection amount control device for an internal combustion engine according to claim 1, wherein the correction coefficient is a predetermined constant value. 3. The fuel injection amount control device for an internal combustion engine according to claim 1, wherein the correction coefficient increases according to the magnitude of the catalyst activity. 4. The apparatus according to claim 1, wherein the correction coefficient changes according to the magnitude of the accelerator opening.
The fuel injection amount control device for an internal combustion engine according to any one of the above. 5. The fuel injection for an internal combustion engine according to claim 4, wherein the correction coefficient increases stepwise or continuously from a predetermined value including 0 according to the magnitude of the accelerator opening. Quantity control device. 6. An accelerator speed calculating means for calculating an accelerator stepping speed which is a time change of the accelerator opening from the accelerator opening, wherein the correction coefficient changes according to the accelerator stepping speed. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 5. 7. The fuel injection of an internal combustion engine according to claim 6, wherein the correction coefficient increases stepwise or continuously from a predetermined value including 0 in accordance with the magnitude of the accelerator pedal depression speed. Quantity control device. 8. A catalyst activity detecting step for detecting an active state of a catalyst for purifying exhaust gas, an accelerator opening detecting step for detecting an accelerator opening which is an accelerator depression amount of a driver, and a predetermined air-fuel ratio. A fuel injection amount calculation step of calculating a fuel injection amount based on at least the accelerator opening degree; a correction coefficient calculation step of calculating a correction coefficient based on the activity degree of the catalyst; and If not fully activated, and if the accelerator opening increases, according to the catalyst activation state, multiplying the fuel correction amount by the correction coefficient to correct the fuel correction amount, A fuel injection amount control method for an internal combustion engine, characterized in that the THC emission amount is reduced. 9. An accelerator speed calculating step for calculating an accelerator stepping speed which is a time change of the accelerator opening from the accelerator opening, wherein the correction coefficient changes according to the accelerator stepping speed. 9. The method for controlling a fuel injection amount of an internal combustion engine according to claim 8, wherein