JPH10141120A - Secondary air quantity control device of internal combust ton engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an engine from being stalled by determining the control input of a control valve opening according to the opening of a throttle when it is detected that the brake is operated below a designated car speed. SOLUTION: On deciding that a throttle opening sensor is normal, it is judged whether a detected velocity V is less than a designated car speed VAIC or less (S108), and if yes, it is judged whether a brake is operated or not (S110). If yes, it is judged what is a shift range of an automatic transmission is (S112), and when it is decided that the running range D, R is selected, a preset table is retrieved by a detected engine rotating speed to obtain a limit value IBSTPLT of the term IBSTP (S114), and this time term IBSTPn is calculated according to a detected throttle opening 6TH (S116). When the obtained term IBSTPn does not exceed this time term IBSTPTn, it is judged whether a value to which a very small value is added or not (S122), if not, it is judged whether designated time elapses or not (S130), and if yes, the term IBSTP is multiplied by this time subtraction coefficient KBSTPn to make decreasing correction (S134).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a secondary air amount control device for an intake system of an internal combustion engine.

[0002]

2. Description of the Related Art A secondary air passage (auxiliary air passage) is provided for bypassing a throttle valve provided in an intake system of an internal combustion engine. A technique of performing feedback control so that the engine speed reaches a target speed at one time and performing open-loop control when the engine is not in an idle state is known, for example, from Japanese Patent Publication No. 5-15909.

Furthermore, in the technique described in Japanese Patent Publication No. 2-43019, the control valve opening is controlled in accordance with the variation of the engine speed when the engine speed is decreasing toward the target speed. It is proposed to increase the amount of secondary air (so-called shot air correction) to thereby prevent engine stall when the engine speed drops sharply.

[0004] In the technology described in Japanese Patent Publication No. 2-43019, more specifically, the engine speed is lower than an idling speed (hereinafter referred to as "NA"), and the threshold value on the lower speed side ("NA") is further reduced. When the engine speed falls below “NSA”, the secondary air amount is supplied for a predetermined time according to the fluctuation amount of the engine speed during one cycle.

[0005]

However, in the above-described prior art (Japanese Patent Publication No. 2-43019), since the secondary air amount is supplied after the engine speed falls below a threshold value (NSA), the vehicle Is an engine load, for example, when the travel range is selected (in-gear) and the brake is operated when the vehicle is stopped (or at extremely low vehicle speed), the accelerator pedal is depressed once and suddenly closed. When the operation is performed, the supply of the secondary air amount cannot be made in time, and the engine speed drops rapidly, and in some cases, the engine may be stalled.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, to supply a secondary air amount in advance to an operation state in which the vehicle is subjected to an engine load, and to quickly close the accelerator pedal once depressed. It is an object of the present invention to provide a secondary air amount control device for an internal combustion engine in which even if a so-called snap operation is performed, the engine speed does not suddenly drop and the engine does not stall.

[0007]

To achieve the above object, according to the present invention, there is provided a secondary air passage which bypasses a throttle valve provided in an intake system of an internal combustion engine. A secondary air amount control device for an internal combustion engine having a control valve disposed therein and controlling a secondary air amount supplied to the internal combustion engine using the control valve opening as an operation amount. Vehicle speed detecting means for detecting a vehicle speed, brake operation detecting means for detecting an operation of a brake for braking the running of the vehicle, throttle opening detecting means for detecting an opening degree of the throttle valve, wherein the detected vehicle speed is equal to or less than a predetermined value. When the operation of the brake is detected, control value determining means for determining a control value of the control valve opening according to the detected throttle opening, based on at least the determined control value. Command value calculating means for calculating a command value of the control valve opening, and was composed as a control valve drive means for driving the control valve based on the output of the command value calculating means.

According to a second aspect of the present invention, an engine speed detecting means for detecting an engine speed of the internal combustion engine, and a limit value determining device for determining a limit value of the control value in accordance with the detected engine speed. Means, the control value determining means,
The control value is determined so as to be equal to or less than the determined limit value.

According to a third aspect of the present invention, the control value determining means is configured to determine the control value over a predetermined time.

[0010]

According to the first aspect of the present invention, when the detected vehicle speed is equal to or lower than a predetermined value, and when the operation of the brake is detected, the control value of the control valve opening is determined according to the detected throttle opening. (Operating amount), the so-called snap operation in which the accelerator pedal is once depressed once and suddenly closed by increasing the secondary air amount in advance to an operating state in which the vehicle becomes an engine load. Even if it is performed, the engine speed does not drop sharply, so that the engine does not stall.

According to a second aspect of the present invention, the control value is determined in accordance with the detected engine speed and the control value is determined to be equal to or less than the limit value. Values can be kept to the minimum necessary.

According to the third aspect of the present invention, since the control value is determined over a predetermined time, the supply of the secondary air amount can be performed smoothly, and the engine speed does not change suddenly.

[0013]

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

FIG. 1 is a schematic diagram generally showing a secondary air amount control device for an internal combustion engine according to the present invention, and reference numeral 10 indicates, for example, a four-cylinder internal combustion engine. An intake pipe 12 is connected to the internal combustion engine 10, a throttle body 14 is provided in the middle of the intake pipe 12, and a throttle valve 16 is disposed inside. The throttle valve 16 has a throttle opening sensor 18.
(Shown as “θTH” in the figure) is connected, converts the throttle opening into an electric signal, and sends it to an electronic control unit (hereinafter “EC”).
U ") 20.

A fuel injection valve 24 is provided downstream of the throttle body 14 and slightly upstream of an intake valve (not shown) of each cylinder combustion chamber (not shown). The fuel injection valve 24 is connected to a fuel pump (not shown) and is electrically connected to the ECU 20. The valve opening time is controlled by a signal from the ECU 20, and a corresponding amount of fuel is supplied to the cylinder.

In the intake pipe 12, the fuel injection valve 24
A secondary air passage 26 that connects the inside of the intake pipe 12 and the atmosphere is connected between the throttle body 14 and the throttle body 14. An air cleaner 28 is attached to the open end of the secondary air passage 26, and a control valve (EACV) 30 for controlling the amount of secondary air is disposed in the middle of the secondary air passage 26.

The control valve 30 is a normally-closed type, and is a valve body 30a that continuously changes the opening degree (opening area) of the secondary air passage 26.
And a spring 3 for urging the valve body 30a in the closing direction.
0b, an electromagnetic solenoid 30c for moving the valve 30a in the opening direction against the urging force of the spring 30b when energized.
Consists of

An absolute pressure sensor 34 is provided downstream of the throttle valve 16 of the throttle body 14 via a branch pipe 32.
(Indicated as “PBA” in the figure) is provided to detect the intake pipe pressure in absolute pressure. In the vicinity of a cooling water passage (not shown) of the internal combustion engine 10, an engine cooling water temperature sensor 40 ("TW" in the figure) is provided.
) Is provided to detect the engine cooling water temperature.

A crank angle sensor 42 (“N” in the figure) is provided near a rotating portion such as a crankshaft (not shown) of the engine.
E) is provided to detect a predetermined crank angle related to TDC and a unit crank angle obtained by subdividing it. An atmospheric pressure sensor 44 is provided near the internal combustion engine 10 and detects the atmospheric pressure at a location where the internal combustion engine 10 is located.

Further, the output of the internal combustion engine 10 is provided with an automatic transmission (FIG. 1) having a four-speed forward and reverse one-speed transmission mechanism and a travel range such as D and R and a non-travel range such as P and N. And "A / T"), and the internal combustion engine 10 and the automatic transmission AT are integrally mounted on a vehicle (not shown).

A vehicle speed sensor 46 is provided near a drive shaft (not shown) of the vehicle.
A signal per rotation is output, and a brake switch 48 is provided near the brake (not shown).
Detects whether the brake has been actuated.

Further, a power steering switch 50 for detecting the operation of the hydraulic power steering mechanism (not shown) is provided near the automatic transmission. The internal combustion engine 1
At 0, a variable valve timing mechanism (indicated as "VT" in the figure) that switches the lift amount and opening / closing timing of the intake valve and the exhaust valve according to two kinds of high and low characteristics according to the engine speed (and the engine load). Provided. The variable valve timing mechanism VT is provided with a valve timing sensor 52 for detecting a selected timing characteristic.

The output of the absolute pressure sensor 34 and the like is
It is sent to the ECU 20. The ECU 20 includes an input circuit 20a and a CPU 20b that shape input signal waveforms from various sensors, correct a voltage level to a predetermined level, and convert an analog signal into a digital signal.

The CPU 20b counts the output of the crank angle sensor 42 to calculate the engine speed NE, counts the output of the vehicle speed sensor 46 to calculate the vehicle speed V, and performs other operations temporarily stored in the storage means 20c. Based on the parameters, an energization current command value (hereinafter, referred to as "ICMD") is determined according to a program stored in the storage means 20c, supplied to the electromagnetic solenoid 30c as an operation amount via the output circuit 20d, and its opening degree (opening area). ) And adjust 2
Control the amount of secondary air.

In the illustrated device, ICMD and
It is configured to be proportional to the amount of secondary air supplied to the intake pipe 12 through the secondary air passage 26.

Next, the operation of the secondary air amount control device for an internal combustion engine according to the present invention will be described.

FIG. 2 is a main flow chart showing the operation. The illustrated program is started at a predetermined crank angle of each cylinder TDC or the like.

First, in S10, various load terms ILOAD are calculated. This is the AC not shown
It is a total value of terms for loads such as a generator, an air conditioner, an electric load, and the above-described hydraulic power steering mechanism. However, the throttle fully closed load term IBSTP described later is not included.

Then, the process proceeds to S12, where the dashpot term I
Calculate DP. In order to prevent the air-fuel ratio from becoming over-rich when the engine is decelerated, the throttle valve 16 is temporarily stopped at a position where it is opened at a constant opening, and then gradually closed to a fully closed position to prevent sudden opening of the throttle valve. Pot control is performed, and IDP is a term corresponding thereto.

Then, the program proceeds to S14, in which a throttle fully closed load term IBSTP (corresponding to the above-mentioned "control value") is calculated.

FIG. 3 is a subroutine flowchart showing the operation.

As described above, when the vehicle is under engine load, for example, when the travel range is selected (in-gear) and the brake is operated when the vehicle is stopped (or at extremely low vehicle speed), the accelerator pedal is released. Once the so-called snap is performed once the pedal is stepped on and suddenly closed, the supply of the secondary air amount cannot be made in time, and the engine speed falls sharply, possibly causing the engine to stall.

Therefore, when this term or control value (operating amount) is newly established and the vehicle is in an operating state in which the engine load is applied, FIG.
As shown in (2), even if the secondary air amount is increased over a predetermined period in advance, even if the throttle valve is returned to the fully closed position, the engine speed NE does not drop sharply with respect to the target speed so that engine stall does not occur. did.

In the following, in S100, it is determined by an appropriate method whether or not the throttle opening sensor 18 has failed (failure). If a failure has occurred, the process proceeds to S102 and the value of the subtraction coefficient KBSTP (described later) is used as it is as the current value. KBSTP
n.

In this and other figures, n added to the quantity symbol is a discrete sample time (more specifically, FIG.
(Start time of the flow chart) indicates the current time, and nm indicates the time m times earlier than that. Therefore, n
Indicates the current value, and the case where n-1 is added indicates the previous value. However, if the current time n and the time are not important, the additional description is omitted.

Then, the program proceeds to S104, in which the value of the throttle fully closed load term IBSTP is set to zero, and to S106, tmIBSTP is set in a timer (down counter), that is,
Start timing.

When the result in S100 is NO, the program proceeds to S108, in which the detected vehicle speed V is adjusted to a predetermined vehicle speed VAIC (for example, 3 kV).
m / h) or less, and if not, the term IBSTP is not calculated because the load acting on the engine of the vehicle is small, and the process proceeds to S102 and thereafter.

When the determination in S108 is affirmative, for example, when it is determined that the vehicle is stopped, the process proceeds to S110, and it is determined whether or not the brake is operated based on the output of the brake switch 48. When the determination is negative, the process proceeds to S102 and thereafter. Along with
When the result is affirmative, the program proceeds to S112, in which the shift range of the automatic transmission is determined. When it is determined that the vehicle is in the non-traveling range such as N or P, the process proceeds to S102 and thereafter.

No in S108, S110, or S1
When the vehicle is in the non-traveling range in step 12, the routine proceeds to step S102, where the term IB
STP is not calculated because these conditions are
This is because it does not impose a great load on

On the other hand, when the driving ranges D and R are selected in S112, that is, when it is determined that the
The routine proceeds to 14, where a preset table is searched from the detected engine speed NE to obtain a limit value (upper limit value) IBSTPLT of the term IBSTP. FIG. 5 is an explanatory graph showing the characteristics of the table, and the limit value IBSTPL
T is set to increase as the engine speed NE increases. Needless to say, the higher the engine speed NE, the greater the degree of sudden decrease in the engine speed. Therefore, it is necessary to increase the term IBSTP.

Then, the program proceeds to S116, in which the current term IBSTPn is calculated in accordance with the detected throttle opening θTH. More specifically, from the detected throttle opening θTH, the throttle opening corresponding to the fully closed position (θTHIDLL + D
(θTHBSTP) is multiplied by a coefficient KIBSTP (for example, 50).

The reason why the throttle opening corresponding to the fully closed position is subtracted is that the throttle valve 16 mechanically assumes that the fully closed position is not zero, and considers this equivalent position to be the fully closed position. The reason why the term IBSTP is basically calculated in proportion to the throttle opening is that the larger the throttle opening is, the larger the sudden change of the load is, and hence the larger the sudden decrease of the engine speed is.

Then, the program proceeds to S118, in which the obtained term IBST is obtained.
P, more specifically, it is determined whether or not the current term IBSTPn exceeds the retrieved current limit value IBSTPLTn. IBST
It is determined whether or not P is equal to or less than a value obtained by adding the minute value DIBSTP to the current value.

When the result in S122 is affirmative, the program proceeds to S124, in which the subtraction coefficient KBSTP is updated, and the program proceeds to S126, where the current term IBSTPn is determined. This is to prevent the control hunting by passing the reduction process because the secondary air amount fluctuation amount is small, in other words, the throttle opening degree closing direction fluctuation is small. Then, the program proceeds to S128, in which the timer tmIBSTP is set to start counting down.

On the other hand, when the result in S122 is NO, S13
The program proceeds to 0 to determine whether or not the timer value tmIBSTP has reached zero, in other words, whether or not a predetermined time has elapsed. If not, the procedure proceeds to S132, where the term IBSTP is left as it is, and the program is temporarily terminated. .

In the next and subsequent program loops, S1
If affirmative in step 30, the process proceeds to step S134, where the term IBSTP
Is multiplied by the current subtraction coefficient KBSTPn (for example, 0.992), and the decrease is corrected. That is, as shown in FIG. 4, after the elapse of a predetermined time, the process of decreasing the increased secondary air amount is started.

Subsequently, the flow advances to S136, where the above-described load term I
It is determined whether or not the value of the power steering term IPS in LOAD is zero, in other words, whether or not the power steering mechanism has been operated by turning the steering wheel (not shown). If the result is affirmative, the process proceeds to S138. , Previous subtraction coefficient KBSTP
The difference obtained by subtracting the minute value DKBSTP (for example, 0.047) from n-1 is used as the current subtraction coefficient KBSTPn. If the difference is negative, the process proceeds to S140, and the previous subtraction coefficient KBST
Pn-1 to another minute value DKBSTPPS (for example, 0.
035) is used as the current subtraction coefficient KBSTPn.

As described above, the reason why the subtraction coefficient when turning, that is, when the power steering mechanism operates is smaller than the subtraction coefficient when not operating is that the load on the hydraulic pump increases when the power steering mechanism operates. As a result, the amount of decrease in the engine speed increases, and accordingly, the degree of decrease in the increased secondary air amount is reduced.

Then, the process proceeds to S142, in which the current subtraction coefficient KB is calculated.
It is determined whether or not STPn is less than zero.
The process proceeds to 44 to replace the value with zero. If the result is negative, the process proceeds to S146 to determine whether the term IBSTP is less than the current item IBSTPn. If the result is affirmative, the process proceeds to S148 to determine the current item IBSTPn. This is because, when the throttle valve driving is stopped halfway, the reduction processing is not performed below the secondary air amount corresponding to the throttle opening. Then S
Proceeding to 150, the timer tmIBSTP is set to start counting down.

Returning to the flow chart of FIG.
Proceeding to 16, it is determined whether the engine is in the start mode.
This is performed, for example, by detecting whether the ignition switch is turned on or whether the cranking motor is operating. When the result in S16 is affirmative, the program proceeds to S18, in which the flag F. The bit of FB (to be described later) is reset to zero, and the process proceeds to S20 to set the secondary air amount in the start mode equation, specifically, ICMD = (ICRST + ILOAD) × KIPA + I
Calculate with PA.

Here, ICRST: basic value of the starting mode, KIPA, IPA: terms for compensating the charging efficiency due to the atmospheric pressure in the multiplication form and the addition form. Subsequently, the program proceeds to S22, where the calculated command value ICMD is changed from 0% to 1
A limit check is performed so as to be within the range of 00%.

When the result in S16 is NO, the program proceeds to S24, in which the flag F. It is determined whether the bit of THIDLE is 1 or not.
This flag is set to 1 when the detected throttle opening is equal to or greater than a predetermined opening (e.g., 5 degrees) corresponding to full closing. If the determination in S24 is negative, that is, if it is determined that the detected throttle opening is at the fully-closed equivalent opening, the process proceeds to S26,
Flag F. It is determined whether the NA bit has been reset to 0.

Flag F. The bit of NA is reset to zero when the engine speed NE falls below the idle determination speed NA. That is, the fact that the bit of this flag is zero means that the engine speed is decreasing toward the target speed.

When the result in S26 is affirmative, the program proceeds to S28,
The aforementioned dashpot term IDP is set to zero, and S30
The program proceeds to S32, where the current term IBSTPn is set to zero, and the program proceeds to S32, where the shot air term ISA is calculated in preparation for idle speed feedback control. This shot air term is, as mentioned above, one cycle of the engine speed (ie, 4 cycles).
It is calculated according to the rate of change between TDCs.

FIG. 6 is a subroutine flowchart showing the calculation of the shot air term ISA.

In the following, a description will be given of the case where the flag F. A
It is determined whether or not the bit of ST is set to 1, in other words, whether or not it is after the start. If not, the process proceeds to S202, where the bit of the timer tmSA is reset to zero, and S2
In step 04, the value of the shot air term ISA is set to zero, and the program ends.

On the other hand, if affirmative in S200, that is, if it is determined that the engine has been started, the routine proceeds to S206, where the detected engine coolant temperature TW is detected.
, A table is searched for, and a shot air start rotation speed (the threshold value) NSA, a rotation speed variation threshold value DNSA, a timer value tmSA, and a coefficient KISA are obtained. 7 to 9 show the characteristics of these tables.

Then, the program proceeds to S208, in which it is determined whether or not the detected engine speed NE is greater than the threshold value NSA. If the result is affirmative, that is, if it is determined that the engine speed is still above the threshold value, the program proceeds to S202. As the process proceeds, when the result is denied, S210
Then, it is determined whether or not the previously detected rotational speed NEn-1 exceeds the threshold value in the same manner. If the result is negative, the process proceeds to S212 to determine whether or not tmSA has reached zero. S212
When affirmative, the program proceeds to S202 and thereafter, and when negative, the program ends.

On the other hand, if the result in S210 is affirmative, S21
4, one cycle before the current detected rotation speed, that is, 4T
The amount of change DENEYL from the detected rotational speed before DC is obtained, and the sign thereof, that is, whether the value is a positive value (increase in rotational speed) or a negative value (decrease in rotational speed) is determined. If it is determined in step S214 that the rotation speed is increasing, the flow proceeds to step S202 because the shot air term for preventing the rotation speed from decreasing is unnecessary.

When it is determined in S214 that the rotational speed is decreasing, the flow proceeds to S216, where the rotational speed variation DN
It is determined whether or not the absolute value of ECYL exceeds the search value DNSA.
If affirmative, the process proceeds to S218, where the timer value tmS
Set A to start counting down. Then S2
Proceeding to 20, the multiplication of the rotational speed fluctuation amount DENEYL by the above-mentioned search coefficient to calculate the shot air term ISA, and proceeding to S222, the limit value is determined.

FIG. 10 is a subroutine flowchart showing the operation.

In the following, the shift range is determined in S300, and if the shift range is determined to be the D range or the R range, the flow proceeds to S302, where the detected vehicle speed V is compared with the predetermined vehicle speed VAIC, and S304 or S306 is performed according to the comparison result. Proceed to. If it is determined in step S300 that the vehicle is not in the travel range, the process immediately proceeds to step S304.

Returning to the flow chart of FIG.
Proceeding to 224, it is determined whether the calculated shot air term exceeds the currently determined limit value.
Proceeding to 26, the calculated value is limited to the limit value, and if negative, the process proceeds to S212.

Returning to the flow chart of FIG.
34, the shift range is determined. If the shift range is determined, the process proceeds to S36, where the flag F. The bit of FB is reset to zero, and the routine proceeds to S38, where the secondary air amount is calculated as follows based on the open (control) mode equation. ICMD = (ITW × IXREFM + ISA + ILOA)
D) × KIPA + IPA Here, ITW is a basic value determined based on the engine cooling water temperature TW, and IXREFM is a learning correction term.

Then, the program proceeds to S40, in which it is determined whether or not a failure has occurred in the control valve 30 or the like.
Proceeding to 2, the secondary air amount is calculated based on the same fail-safe mode equation as the above-described open mode equation.

On the other hand, when it is determined in S34 that the vehicle is not in the travel range, the flow proceeds to S44, the bit of the flag is set to 1, and the flow proceeds to S46 to determine the secondary air amount based on the feedback (control) mode equation. calculate. For more information: a. Flag F. When FB = 1, feedback control is performed. ICMD = (IFBn + ISA + ILOAD) × KIP
A + IPA Here, IFBn is a feedback correction term calculated according to a deviation from a predetermined target rotation speed. b. Flag F. When FB = 0, open loop control is performed. If V> VAIC ICMD = (IDP + ILOAD) × KIPA + IPA If V ≦ VAIC ICMD = (IBSTP + ILOAD) × KIPA + I
PA

As described above, the shot air term ISA and the throttle fully closed load term IBSTP or the dashpot term IDP are alternatively used, and the throttle fully closed load term IBSTP and the dashpot term ID according to the vehicle speed.
P is also used alternatively.

On the other hand, if affirmative in S24, that is, if it is determined that the detected throttle opening is relatively high, the program proceeds to S48.
To flag F. Reset the bit of FB to zero,
The program proceeds to 50, where it is determined whether the detected engine speed NE exceeds a predetermined engine speed NG (for example, 6000 rpm). ) Is calculated in accordance with the following formula, and the process proceeds to S22. If the result is NO, the process proceeds to S46 to calculate the secondary air amount according to the feedback (control) mode equation.

If the result in S26 is NO, the program proceeds to S54, in which the bit of the flag is reset to zero, and the program proceeds to S56, in which the deceleration secondary air amount term IDEC is calculated. this is,
When the intake negative pressure is large (that is, the absolute pressure is small) at the time of full throttle deceleration of the throttle, the oil pressure consumption increases, and this is a term set as a preventive measure.

FIG. 11 is a subroutine flowchart showing the operation.

In the following, it is determined whether or not the detected engine speed NE exceeds NIDEC (for example, 1000 rpm) in S400. If the result is negative, that is, if the engine speed is relatively low, the process proceeds to S402 and the deceleration secondary is performed. Air volume term I
The value of DEC is set to zero, and when the result is affirmative, that is, when it is determined that the engine is running at a relatively high speed, the routine proceeds to S404, where it is determined whether or not the fuel is cut.

If the result in S404 is NO, S4
02, when the result is affirmative, the process proceeds to S406 to determine whether the engine cooling water temperature TW exceeds the predetermined water temperature TWIDEC. When the result is negative, the process proceeds to S402, and when the result is affirmative, the process proceeds to S408 to perform detection. It is determined whether the vehicle speed V exceeds a predetermined vehicle speed VIDEC (for example, 5 km / h). If not, the process proceeds to S402.

On the other hand, if affirmative, the process proceeds to S410, where it is determined whether the value of the dashpot term IDP is zero. If negative, the process proceeds to S402.
Proceeding to 412, it is determined whether the value of the throttle fully closed load term IBSTP is zero. If the result is negative, the process proceeds to S402, and if the result is affirmative, the process proceeds to S414. That is, the deceleration secondary air amount term IDEC is set so that the dashpot term IDP and the throttle fully closed load term IBSTP do not overlap.

Subsequently, the flow advances to S414, and F.S. From VTEC, high-side characteristics (HiV /
T) or the lower side characteristic (LoV / T) is determined, and S416 or S4 is selected according to the determination result.
The program proceeds to step 18, wherein a corresponding table is searched by the detected engine speed NE to calculate a deceleration secondary air amount term IDEC. FIG.
Shows the characteristics of the table. Here, the deceleration secondary air amount term IDEC increases in proportion to the engine speed because the higher the engine speed, the greater the deceleration.

Returning to the flow chart of FIG.
Proceeding to 58, it is determined whether the value of the term IDEC is zero or not. If affirmative, the process proceeds to S46, and if negative, S6
Go to 0 and set the secondary air volume according to the DEC open loop (control) equation ICMD = (IDEC + IXREF) × KIPA + IP
A is calculated. Here, IXREF is a learning correction term.

With the above configuration, the secondary air amount is supplied in advance to an operating state in which the vehicle becomes an engine load, and the engine is operated even if a so-called snap operation is performed, in which the accelerator pedal is once depressed and suddenly closed. There is no sudden drop in the engine speed, so that the engine does not stall.

FIG. 13 is a timing chart showing the control according to this embodiment in comparison with the prior art.
Although it is a chart, the term IBSTP (control value (operating amount))
Is provided in advance, the supply delay of the secondary air amount does not occur.

Further, the control value is determined in accordance with the detected engine speed, and the control value is determined so as to be equal to or less than the determined limit value. Since the control value can be set to the limit and the control value is determined over a predetermined time, the secondary air amount can be supplied smoothly and the engine speed does not change suddenly.

As described above, in this embodiment,
Throttle valve 1 provided in intake system 12 of internal combustion engine 10
Secondary air amount control for an internal combustion engine, which has a control valve 30 disposed in a secondary air passage 26 bypassing the control valve 6 and controls the amount of secondary air supplied to the internal combustion engine using the control valve opening as an operation amount In the apparatus, a vehicle speed detecting means (vehicle speed sensor 46) for detecting a vehicle speed V of a vehicle on which the internal combustion engine is mounted, a brake operation detecting means (brake switch 48) for detecting an operation of a brake for braking the running of the vehicle, Throttle opening detecting means (throttle opening sensor 18) for detecting the opening θTH of the throttle valve;
Is equal to or less than a predetermined VAIC, and when the operation of the brake is detected, control value determining means for determining a control value IBSTP of the control valve opening in accordance with the detected throttle opening θTH (FIG. 2 flow chart). S14 and FIG.
S108, S110, S112, S of the flow chart
116) a command value calculating means for calculating a command value ICMD of the control valve opening based on at least the determined control value; and a control valve for driving the control valve 30 based on the output of the command value calculating means. The driving means (electromagnetic solenoid 30c) is provided.

Further, an engine speed detecting means for detecting an engine speed NE of the internal combustion engine, and a limit value IBS of the control value IBSTP according to the detected engine speed NE.
Limit value determining means for determining TPLT (FIG. 3 flow
S114) of the chart, wherein the control value determining means includes:
The control value is determined so as to be equal to or less than the determined limit value (S118 and S120 in the flowchart of FIG. 3).
It was configured so that

The control value determining means is configured to determine the control value IBSTP over a predetermined time tmIBSTP.

[0082]

According to the first aspect, the so-called snap operation in which the accelerator pedal is depressed once and suddenly closed by increasing the amount of secondary air in advance in an operating state in which the vehicle becomes an engine load. Is performed, the engine speed does not drop sharply, so that the engine does not stall.

According to the second aspect, the control value can be reduced to a necessary minimum.

According to the third aspect, the supply of the secondary air amount can be performed smoothly, and the engine speed does not suddenly change.

[Brief description of the drawings]

FIG. 1 is a schematic diagram generally showing a secondary air amount control device for an internal combustion engine according to the present invention.

FIG. 2 is a main flow chart showing the operation of the apparatus shown in FIG.

FIG. 3 is a subroutine flowchart showing a calculation operation of a throttle fully closed load term in the flowchart of FIG. 3;

FIG. 4 is an explanatory graph showing a throttle fully closed load term calculated in FIG. 3;

FIG. 5 is an explanatory graph showing characteristics of a limit value of a throttle fully closed load term calculated in FIG. 3;

FIG. 6 is a subroutine flowchart showing a calculation operation of a shot air term in the flowchart of FIG. 2;

7 is a shot air start rotation speed NSA and a rotation speed fluctuation amount threshold value D used in the calculation of the flow chart of FIG. 6;
4 is an explanatory graph showing characteristics of NSA.

FIG. 8 is an explanatory graph showing characteristics of a timer value tmSA used in the calculation of the flowchart of FIG. 6;

FIG. 9 shows a coefficient K used in the calculation of the flow chart of FIG.
4 is an explanatory graph showing characteristics of ISA.

FIG. 10 is a subroutine flowchart showing a calculation operation of a limit value of a shot air term used in the calculation of the flowchart of FIG. 6;

FIG. 11 is a subroutine flowchart showing a calculation operation of a deceleration secondary air amount term in the flowchart of FIG. 3;

FIG. 12 is an explanatory graph showing characteristics of a deceleration secondary air amount term in the flowchart of FIG. 11 for each valve timing.

FIG. 13 is a timing chart showing the secondary air amount control according to the present invention in comparison with the prior art.

[Explanation of symbols]

 Reference Signs List 10 internal combustion engine 12 intake pipe 16 throttle valve 18 throttle opening sensor 20 ECU 26 secondary air passage 30 control valve 46 vehicle speed sensor 48 brake switch

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Ryuji Sato 1-4-1 Chuo, Wako-shi, Saitama Pref.

Claims (3)

[Claims] A control valve is provided in a secondary air passage that bypasses a throttle valve provided in an intake system of an internal combustion engine, and a secondary valve that supplies the control valve opening as an operation amount to the internal combustion engine. A secondary air amount control device for an internal combustion engine for controlling an air amount, comprising: a. Vehicle speed detecting means for detecting the speed of a vehicle on which the internal combustion engine is mounted; b. Brake operation detecting means for detecting operation of a brake for braking the traveling of the vehicle, c. Throttle opening detecting means for detecting the opening of the throttle valve; d. Control value determining means for determining a control value of the control valve opening in accordance with the detected throttle opening when the operation of the brake is detected when the detected vehicle speed is equal to or lower than a predetermined value; e. Command value calculation means for calculating a command value of the control valve opening based on at least the determined control value,
And f. A control valve driving means for driving the control valve based on an output of the command value calculating means. 2. g. Engine speed detecting means for detecting the engine speed of the internal combustion engine; h. Limit value determining means for determining a limit value of the control value according to the detected engine speed, wherein the control value determining means determines the control value so as to be equal to or less than the determined limit value. 2. The secondary air amount control device for an internal combustion engine according to claim 1, wherein: 3. The secondary air amount control device for an internal combustion engine according to claim 1, wherein the control value determining means determines the control value over a predetermined time.