JP3196294B2 - Auxiliary air flow control device for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary air flow for an engine for controlling the amount of auxiliary air supplied to an engine from an auxiliary air passage provided to bypass a throttle valve provided in an intake pipe of the engine. The present invention relates to a control device, and more particularly to control of an auxiliary air amount when a transition from a non-idle state to an idle state of an engine is performed.

[0002]

2. Description of the Related Art Conventionally, an auxiliary air amount control device for an engine is disclosed in Japanese Patent Application Laid-Open No. 3-258949.
This is because, as shown in FIGS. 21 and 22, the charging of the deceleration air amount is delayed due to the delay of the intake system, and the engine intake air amount is insufficient, so that the torque is insufficient and the rotation is reduced. Therefore,
In the above publication, as indicated by A in FIG. 22, the throttle passage air amount is supplemented so that the engine intake air amount does not fall below a required air amount (constant amount) during stable idling.

In FIG. 23, an engine intake air amount Gou
When t is constant, the engine speed N and the intake pressure P change along the equal air amount line shown in FIG. 24 so that the equal air amount is obtained. Considering the case where the vehicle is decelerated from a certain operation state on the iso-air flow line (rotation speed-intake pressure curve) in FIG.
The engine intake air amount (indicated by a dotted line in the figure) becomes lower than the stable idle intake air amount during deceleration. As a result, the rotation decreases. On the other hand, in order to control the engine intake air amount at the time of deceleration to be constant (= stable intake air amount at the time of stable idling), as shown by a solid line in the figure, along the constant air amount line required to maintain idling. Just return to idol.

Therefore, as shown in FIG. 25, the intake pressure when the engine intake air amount is constant can be uniquely determined with respect to the rotational speed from an equal air amount line required to maintain idling. That is, if the auxiliary air amount is controlled so that the intake pressure becomes a pressure determined from the constant air amount line at the time of stable idling, the engine intake air amount can be set to the air amount at the time of stable idling, thereby preventing a decrease in rotation.

More specifically, since the constant air amount line is shifted by the engine load, in the above-mentioned publication, the change in the intake pressure per unit time can be determined from the constant air amount line with respect to the rotational speed. An air amount proportional to the difference is added so that the amount (target value) is obtained, and feedback is performed by so-called proportional control.

[0006]

However, since there is a volume in the intake system, a delay occurs when the amount of air passing through the throttle is actually reflected in the torque. This delay varies from engine to engine. In the above publication, the amount of air proportional to the difference is added so that the amount of change in the intake pressure per unit time is the amount of change in the intake pressure that is uniquely determined with respect to the rotational speed from the constant air amount line. Therefore, in order to prevent a decrease in rotation immediately after deceleration, the proportional gain Kp had to be set larger for an engine with a larger delay in the intake system.

However, when the target value is generally constant in the feedback control, as shown in FIG.
When the proportional gain Kp is increased, the control amount is sensitively reflected even if the deviation is small. Therefore, the actual intake pressure change amount oscillates (hunts) around the target intake pressure change amount, and the control amount also increases. Hunting appears in the rotation speed repeatedly, and the feeling is adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to provide an auxiliary air amount control device for an engine that can make the engine speed equal to a target value while preventing hunting.

[0009]

According to the present invention, as shown in FIG. 27, an auxiliary air passage for guiding auxiliary air from a throttle valve upstream to a throttle valve downstream by bypassing a throttle valve disposed in an intake pipe of an engine. M1 and the auxiliary air passage M
1, an actuator M2 for adjusting a flow rate of the auxiliary air, and an intake pressure detecting means M3 for detecting an intake pressure.
And an engine speed detecting means M4 for detecting an engine speed, and a storage storing a relationship between the engine speed and the intake pressure when the engine intake air amount is constant when shifting from the non-idle state to the idle state. A target intake pressure corresponding to the engine speed by the engine speed detecting means M4 is obtained by using the means M5 and the data of the storage means M5, and a time differential value of the intake pressure and the intake pressure detecting means M3 are obtained.
And an actuator control means M6 for controlling the actuator M2 by feedback control having a proportional term and an integral term so that the time differential value of the intake air pressure caused by the intake air pressure coincides with the target intake air pressure.
Time differential value is corrected by the intake pressure at idle.
The gist of the present invention is an auxiliary air amount control device for an engine.

[0010]

[0011]

[0012]

The relationship between the engine speed and the intake pressure when the amount of engine intake air is constant when the engine shifts from the non-idle state to the idle state is stored in the storage means M5. Then, the actuator control means M6 stores the storage means M
5, the target intake pressure corresponding to the engine speed is obtained by the engine speed detecting means M4 so that the time differential value of the intake pressure and the time differential value of the intake pressure by the intake pressure detecting means M3 match. Then, the actuator M2 is controlled by feedback control having a proportional term and an integral term. In the actuator M2, the time of the target intake pressure
The derivative value is corrected by the intake pressure at idle. As a result, the feedback control by adding the integral element to the proportional element, the hunting of the engine speed is prevented co
Then, the engine speed matches the target value .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration diagram around an engine mounted on an automobile. In the intake system of the engine 1, a throttle valve 3 is disposed in an intake pipe 31 upstream of the surge tank 2, and an idle switch 4 that is turned on when the throttle valve 3 is fully closed is attached.
An auxiliary air passage 5 is provided to bypass the throttle valve 3 and supply air from the upstream side of the throttle valve to the surge tank 2 downstream of the throttle valve. The auxiliary air passage 5 is provided with an idle control valve (hereinafter, referred to as an ISC valve) 6 for controlling the amount of auxiliary air. This I
As the SC valve 6, a well-known proportional solenoid (linear solenoid) control valve or a vacuum switching valve (V
SV) or the like is appropriately used. Further, a temperature sensor 7 for detecting the intake air temperature is mounted on the upstream side of the throttle valve 3. Further, a pressure sensor 8 for detecting an intake pressure downstream of the throttle valve 3 is attached to the surge tank 2.
The surge tank 2 is connected to a combustion chamber of the engine 1 via an intake manifold 9 and an intake port 10.
A fuel injection valve 11 is attached to each cylinder so as to protrude into the intake manifold 9.

The combustion chamber of the engine 1 has an exhaust port 1
It is connected to a three-way catalyst (not shown) via the exhaust manifold 2 and the exhaust manifold 13. The exhaust manifold 13 is provided with an O ₂ sensor 14 for detecting a residual oxygen concentration in exhaust gas and outputting an air-fuel ratio signal. Further, a water temperature sensor 16 that penetrates through the engine block 15 and protrudes into the water jacket is attached to the engine block 15 so as to detect a cooling water temperature of the engine 1.

Further, the cylinder head 17 of the engine 1
A spark plug 18 is attached to each cylinder so as to penetrate through and protrude into the combustion chamber. The spark plug 18 is connected via a distributor 19 and an igniter 20 to an electronic control unit (hereinafter, referred to as ECU) 21 composed of a microcomputer or the like. Inside the distributor 19, a cylinder discriminating sensor 22 and a crank angle sensor 23 each composed of a single rotor fixed to a distributor shaft and a pickup fixed to a distributor housing are mounted. In the case of a six-cylinder engine, the cylinder discrimination sensor 22
Outputs a cylinder discrimination signal every 720 ° C., for example, and the crank angle sensor 23 outputs a rotation speed signal every 30 ° C., for example.

As shown in FIG. 2, the ECU 21 includes a central processing unit (CPU) 24, a read-only memory (ROM) 25, a random access memory (RAM) 26, and a backup RAM (hereinafter referred to as "RAM").
A Bu-RAM) 27, an input / output port 28, an analog / digital converter (ADC) 29, and a bus 3 such as a data bus or a control bus for connecting these.
0 is included. And the input / output port 28
, A cylinder discrimination signal, a rotation speed signal, a throttle fully closed signal, and an air-fuel ratio signal are input. Also, the input / output port 28
Is an ISC valve control signal for opening and closing the ISC valve 6, a fuel injection signal for opening and closing the fuel injection valve 11,
An ignition signal for turning on / off the igniter 20 is output to a drive circuit (not shown). The drive circuit controls the ISC valve 6, the fuel injection valve 11, and the igniter 20 according to these output signals.

The ADC 29 receives an intake pressure signal, an intake temperature signal, and a water temperature signal. And ADC2
Numeral 9 sequentially converts these signals into digital signals in accordance with an instruction from the CPU 24.

The Bu-RAM 27 stores an equal air amount map for each engine load shown in FIG.
The equal air amount curve indicates the relationship between the engine speed and the intake pressure when the engine intake air amount is constant when shifting from the non-idle state to the idle state.

In this embodiment, the ISC valve 6 controls the actuator, the pressure sensor 8 controls the intake pressure detecting means, the crank angle sensor 23 controls the engine speed detecting means,
In U24, the actuator control means is
7, a storage means.

Next, the operation of the thus configured auxiliary air amount control device for an engine will be described. 3 to FIG.
4 shows a deceleration control process executed by the PU 24. FIG. 14 is a time chart for explaining the flowchart. Here, the deceleration control is a routine that replaces the dashpot control during deceleration from the time when the idle switch 4 is turned on from the off state to the time when the engine speed reaches the target engine speed. The calculation is repeated until.

First, the state of the idle switch 4 is detected in step 100 of FIG. Here, when the idle switch 4 is off, the routine returns without executing the control amount calculation routine of step 102 and subsequent steps. If the idle switch 4 is ON (timing of t1 in FIG. 14), step 1
Move to 02. Here, the flag N representing the engine state
ISCMODE is the flag N when the idle switch is off.
Since the data has not been rewritten from ISCMODE = 5, the process proceeds to step 103. That is, the deceleration control is performed in step 100,
This is a routine that is executed after the idle switch 4 is changed from the off-state to the on-state at 102, and deceleration control is executed every 100 ms until the end condition is satisfied.

Steps 103 to 105 are an initial setting routine. First, in step 103, the engine 1
A predetermined control amount DISCLRN is set in accordance with the load state of, and the routine proceeds to step 104. More specifically, as will be described later, it corresponds to the load state at that time among the learning control amounts GLRN1, GLRN2, and GLRN3 stored in the Bu-RAM 27 according to the load state of the engine 1 (air conditioner operating state, electric load state, etc.). The learned learning control amount is equal to the predetermined control amount DIS.
Set as CLRN. In step 104, the predetermined control amount DISCLRN set in step 103 is set as the control amount DISC.

Next, the routine proceeds to step 105, where necessary parameters are initialized during the deceleration calculation. For example, Pmr
0 = Pmr, Pt0 = Pt. Next, at step 106, the flag NISCMODE is set to "4" assuming that the idle switch 4 has been turned on from off to on (it is in a deceleration state) and the initial setting of the parameters required for the deceleration control calculation has been completed. That is, NISCMODE = 4 is a flag at the time of control entry during deceleration.

Thereafter, the process returns in FIG. At the next calculation, if the idle switch 4 remains on, the process proceeds from step 100 to step 102, where the flag N
Since ISCMODE has been rewritten to 4, the process proceeds from step 107 to step 108 in FIG.

Steps 108 to 114 determine whether an auxiliary air amount is required for deceleration control, that is, whether the engine intake air amount is less than the air amount necessary for maintaining idling. At 117, the auxiliary air amount DEC is calculated.

First, at step 108, the actual intake pressure Pmr detected by the pressure sensor 8 is read and at step 109
Sets the target intake pressure Pt. In this process, as described later, an equal air amount line is selected for each load applied to the engine,
The target intake pressure Pt is searched from the constant air amount map according to the read engine speed Ne.

Next, the routine proceeds to step 110, where the time differential value of the intake pressure (the amount of change per unit time) is calculated as DELPMR =
It is determined as Pmr-Pmr0. Here, Pmr is the current sampling value, and Pmr0 is the previous sampling value.

In step 111, a time differential value DE of the intake pressure is obtained.
It is detected whether or not LPMR is “0” or more. Here, if the time differential value DELPMR of the intake pressure is equal to or less than "0", the routine proceeds to step 112, where a flag NISC representing the engine state indicating that the intake pressure has shifted in the negative direction during deceleration.
MODE = 10 is set, and the routine proceeds to step 114.

As shown in FIG. 14, NISCMODE =
4 and NISCMODE = 10 indicate that the engine intake air amount Gout is larger than the throttle passing air amount Gin, that is, it is determined that the engine intake air amount is not less than the air amount necessary to maintain the idle state, In this state, the auxiliary air amount DEC is not required.

Since the auxiliary air amount DEC is required at the point where the engine intake air amount Gout is smaller than the air amount necessary to maintain the idle state, as shown in FIG. At a point (indicated by B in FIG. 24) at which the air pressure Pmr matches the target intake pressure Pt obtained from the isometric air volume map with respect to the engine speed Ne (Ne, Pmr behavior during deceleration intersects with the isometric air volume curve). is there. At this time, FIG.
As shown in FIG. 4, Gin ≧ Gout from Gin <Gout. That is, when DELPMR <0 from DELPMR <0. Therefore, the DEC calculation start point is set to DE
This is a point where LPMR <0 to DELPMR ≧ 0.

This will be described with reference to FIG. Immediately after the idle switch 4 is turned on, t1 to t in FIG.
In 2, DELPMR ≧ 0 and the flag NISCM
ODE = 4 is set, and steps 100 → 102 in FIG.
→ 107 → 108 → 109 → 110 → 111 → 1 in FIG.
13 → 114 → 118 → 119 → 120 → 121 in FIG.
And migrate. Then, at time t2 in FIG. 14, when the time differential value DELPMR <0 of the intake pressure is satisfied, step 10 in FIG.
0 → 102 → 107 → 108 → 109 → 110 → 111
In step 112, NISCMODE = 10 is set, and the flow proceeds to steps 114 → 118 → 119 → 120 → 121. In the next process, steps 100 → 102 →
107 → 122 → 108 → 109 → 110 → 111 → 1
The transition is 12 → 114 → 118 → 119 → 120 → 121. This operation is repeated from t2 to t3 in FIG.

When DELPMR ≧ 0 at time t3 in FIG. 14, step 100 in FIG.
102 → 107 → 122 → 108 → 109 → 110 → 1
The process proceeds from 11 to 113, and since NISCMODE = 10, the process proceeds to step 115. And the auxiliary air amount DEC
NISCMO
Set DE to "15". Then, step 116 →
The transition is 117 → 118 → 119 → 120 → 121.

Once NISCMODE = 15 is set, the auxiliary air amount DEC is changed every unit time unless the idle switch 4 is determined to be OFF in step 100 of FIG. 3 or the termination determination is not satisfied in step 121 of FIG. Is calculated.

Since NISCMODE = 15 during the DEC operation, steps 100 → 102 → 107 → 1 in FIG.
22 → 123 → The routine proceeds to 116 in FIG. 4, and in step 116, the time differential value DELPMR of the actual intake pressure Pmr (= Pmr−
Pmr0) is calculated.

Next, the DEC calculation routine of step 117 will be described later with reference to FIG. 8. In this routine, the target intake pressure Pt is searched from the equal air volume map given for each load on the engine, and Time derivative value DEL of intake pressure
The deviation DELP (= DELPT-DELPMR) so that the PMR becomes the time differential value DELPT of the target intake pressure.
The auxiliary air amount DEC is calculated by PI control according to

After the DEL calculation in step 117 in FIG. 4, the process proceeds to step 118 in FIG. 5, and DISCLRN (a value obtained by learning the amount of air necessary to maintain the idling for each load applied to the engine) is changed to the load on the engine. Select according to.

In step 119, the control amount DISC of the ISC valve 6 is changed to the auxiliary air amount DEC and the control amount DI.
The result is obtained by adding SCLRN. Further, in step 120, parameters to be used in the next calculation are stored in the respective RAMs 26, and in step 121, it is determined whether or not an end condition is satisfied.

This termination determination routine will be described later with reference to the flowchart of FIG. 10, but the criteria is that the termination condition is satisfied when the target idle speed Ne is reached. That is,
The engine speed Ne is equal to the target idle engine speed Ne.
And the amount of change in the engine speed Ne | Ne-N
When the state where e0 | is equal to or less than a predetermined value continues for a predetermined time or more, it is determined that the target idle engine speed Ne has been reached, and the auxiliary air amount DEC = 0, and the state is set to a flag NIS
It is represented by CMODE = 7 (see FIG. 14). If the idle switch is on at the next calculation, NISCMODE =
7, step 100 → 102 → 107 in FIG.
→ 122 → 123 → 124 next control (Ne feedback control). The next control in step 124 is to perform rotation feedback control after the engine speed reaches the target idle engine speed, and will be described later.

Since the ISC control amount at the time of shifting to the deceleration control (t1 to t3 in FIG. 14) in step 119 in FIG. 5 is DEC = 0, DISC = DISCLRN
It is.

FIG. 6 shows the DISCLRN selection routine of step 103 of FIG. 3 and step 118 of FIG.
This DISCLRN selection subroutine is a routine for reading out the result of learning the amount of air necessary to maintain idle for each load applied to the engine.

First, at steps 200 and 201, the load on the engine is determined. That is, it is determined in step 200 whether the air conditioner and the electric load are turned on. If the engine is not loaded, the process proceeds to step 202, and the learning value GLRN1 (ISC learning value when the engine is not loaded) is set to DISCLRN.

On the other hand, if it is determined in step 200 that the engine is under load, the routine proceeds to step 201, where it is determined whether the air conditioner is on. And the air conditioner
If it is on (or both the air conditioner and the electric load are on), the process proceeds to step 203, where the learning value GLRN2 (the ISC learning value when the air conditioner is on or the air conditioner and the electric load are on) is set to DISCLRN. Further, when it is determined in step 201 that the air conditioner is not on, that is, when only the electric load is on, the process proceeds to step 204, where the learning value GL is set.
RN3 (ISC learning value when only electric load is on) is DIS
CLRN.

Next, the Pt search routine of step 109 in FIG. 4 will be described with reference to FIG. In this Pt search subroutine, the target intake pressure Pt is searched for the engine speed from an equal air volume map given for each engine load.

First, at step 300, the engine speed N
In step 301, 302, the load applied to the engine is determined. That is, in step 301, the air conditioner
It is determined whether or not the electric load is off. If the electric load is off, in step 303, the engine speed N
The target intake pressure Pt obtained for e is searched. On the other hand, if both or one of them is on in step 301, the process proceeds to step 302 to determine whether the air conditioner is on.

When the air conditioner is on (only the air conditioner is on or both the electric load and the electric load are on), at step 303, a target intake pressure Pt obtained for the engine speed Ne is retrieved from the equal air volume map when the air conditioner is on. .

On the other hand, if it is determined in step 302 that the air conditioner is off (only the electric load is on), step 30
In step 3, a target intake pressure Pt obtained with respect to the engine speed Ne is searched from the equal air amount map when only the electric load is on.

Next, the DEC calculation routine of step 117 in FIG. 4 will be described with reference to FIG. In the DEC calculation routine, during deceleration from the time when the idle switch is turned off to on to the time when the target idle speed Ne is reached, the engine intake air amount falls below the air amount necessary for maintaining idling stably. In order to avoid this, the shortage is calculated as the auxiliary air amount DEC.

First, in step 400, a target intake pressure Pt is searched for an engine speed Ne from an equal air volume map given for each load applied to the engine. Next, in step 401, the target intake pressure Pt0 taken in the previous calculation is calculated.
Then, the time differential value DELPMR of the intake pressure calculated in step 116 of FIG. 4 is read. Then, in step 402, a time differential value DELPT of the intake pressure obtained from the equal air amount curve with respect to the engine speed is calculated as Pt-Pt0. Further, in step 403, a correction coefficient K0 for engine aging is searched from a map provided for each engine load (both the electric load and the air conditioner are off, only the electric load is on, and the air conditioner is on). This processing will be described later.

At step 404, the time differential value D of the intake pressure
By multiplying the ELPT by the correction coefficient K0, the time differential value DELP of the target intake pressure in consideration of the aging of the engine is obtained.
Calculate T. Then, the time differential value DELP of the target intake pressure corrected for the time change of the engine in step 405.
Deviation DE between T and the time differential value DELPMR of the actual intake pressure
Calculate LP.

Thereafter, in step 406, the auxiliary air is controlled by the PI control in accordance with the deviation DELP so that the time differential value DELPMR of the actual intake pressure becomes the time differential value DELPT of the target intake pressure corrected for measures against engine aging. Quantity DEC (= a · DEC0 + b · DELP−c · DELP
0) is calculated. However, DEC0 and DELP0 are
These are the previous values of DEC and DELP.

That is, the inverse Laplace transform of Gc (s) = Kp (1+ (1 / Kis)) gives DEC = DEC0 + {(Kp (1 + Ki / dt) dt / Ki} .DELP−Kp.DELP0 (a = 1, b = ｛(Kp (1 + Ki / dt) dt
/ Ki｝, c = Kp).

Next, the K0 search routine in step 403 in the DEC calculation routine shown in FIG. 8 will be described with reference to FIG. The air flow curve (iso-air flow curve) required to maintain the idling changes with the aging of the engine. Therefore, a term for correcting the deviation of the contour line is required. In the deceleration control, the auxiliary air amount is determined according to the time differential value of the intake pressure obtained for the engine speed from the equal air amount map, so that the time differential of the intake pressure searched from the previously given map is used. It corrects how the time derivative of the required intake pressure at the time of engine aging changes from the value. The correction coefficient K0 is obtained by comparing the intake pressure value at the time of stable idling with the intake pressure value at the time of stable idling (when the rotational speed is the target idle rotational speed) on the predetermined constant air amount line, and calculates the following equation ( 15), which is given as a map for the intake pressure learning value.

First, at steps 450 and 451, the load on the engine is determined. That is, when both the electric load and the air conditioner are off, the operation proceeds to step 452, when the air conditioner is on, the operation proceeds to step 453, and when only the electric load is on, the operation proceeds to step 454. The intake pressures PLRN1 to PLRN3 learned for each engine load during stable idling. Is read, and a correction coefficient K0 is retrieved from a correction coefficient map provided for each engine load in steps 455 to 457 in accordance with the intake pressure learning value.

Here, a method of determining the correction coefficient K0 for countermeasures against engine aging will be described. If the weight of air that the four-cylinder engine takes into the cylinder per second is Gout, Gout is expressed by the following equation.

Gout = (N / 120) · Vc · ηv · γs (1) ηv is a volume efficiency and is represented by the following equation.

Ηv = intake air weight / exhaust weight when engine rotates at stoichiometric air / fuel ratio = G / (Vc · γs)

[0057]

(Equation 1) AF; air-fuel ratio ε; compression ratio Pa; throttle upstream pressure Ps; intake pipe pressure Ra; gas constant upstream of the throttle Ta; gas temperature upstream of the throttle Vs; intake pipe volume γs; air density in the intake pipe Gin; Gout; engine intake air weight N; engine speed Vc; cylinder volume From equations (1) and (2)

[0058]

(Equation 2) Here, AF, Vc, Ra, Ta, ε, and Pa are constants.

The rotational speed N and the intake pressure Ps at the time of stable idling are known. Therefore, Gout = constant (the amount of air required for maintaining idling). Gout = N-P when constant
The curve (isometric curve) is shown in FIG.

The isometric air volume curve given in advance as a map is

[0061]

(Equation 3) k0, k1, k2 and K are constants. N and P change to satisfy the following.

Accordingly, when the amount of air necessary for maintaining the idling changes due to a change with time of the engine (the intake pressure changes at the time of stable idling (when the target idling speed is kept stable)), the equal air The quantity line is

[0063]

(Equation 4) k0, k1, k2 and K 'are constants. To satisfy N,
P changes.

Here, it is difficult for the microcomputer to calculate an equal air amount curve (NP curve) satisfying the expression (5).
Therefore, it will be verified how the time differential value of the intake pressure used in the deceleration control calculation changes when the engine intake air amount Gout = K during stable idling becomes K ′.

Now, as shown in FIG. 17, when the engine speed per unit time has changed from the previous value Nn-1 to the current value Nn, when the engine changes over time, the air amount line required to maintain the idle is Satisfies the expression (5). N = Nn-1 P =
If Ptn-1 ', N = Nn and P = Ptn', the equation (5) becomes

[0066]

(Equation 5) (7)-(6)

[0067]

(Equation 6) The term in equation (8) is of the order of 10 ^-3 and can be ignored.

[0068]

(Equation 7) However, during the deceleration control calculation, according to the intake pressure change per unit time (intake pressure time differential value) obtained with respect to the rotation speed from the constant air volume line given as a map satisfying the equation (4) in advance. The amount of auxiliary air is determined.

Therefore, when N = Nn-1 and N = Nn, the intake pressures (determined from the equal air amount map) satisfying the equation (4) are P = Ptn-1 and P = Ptn, respectively.

[0070]

(Equation 8) Formula (11)-(10)

[0071]

(Equation 9) The terms in equation (12) are negligible compared to terms.

[0072]

(Equation 10) From equations (9) and (13)

[0073]

[Equation 11] That is, when the engine changes over time, the target intake pressure time differential value (a) is a constant ((b) ) K ′ / K), it is possible to obtain the correct amount, and the required amount of auxiliary air can be correctly determined.

Next, a method of calculating K '/ K will be described. Substituting the intake pressure (PTA) into the equation (3) at the time of engine aging and at the time of stable idling (when the engine is running steadily at the target idling speed) in the iso-air curve given in advance as a map Can be obtained.

Intake pressure PTA during stable idling at the time of change over time of the engine PTA = PLRN ', intake pressure PTA during stable idling in an equal air amount curve given in advance as a map =
Assuming PLRN, from equation (3)

[0076]

(Equation 12) ε: compression ratio, Pa: atmospheric pressure, PLRN; known PLRN ′ is substituted into equation (15) as a parameter and K ′
/ K (= K0) is mapped as shown in FIG.

Thus, by learning the intake pressure PTA when the idling is stabilized, the correction coefficient K0 can be retrieved from the three maps. As described above, the correction coefficient K0 is obtained by the correction coefficient map given for each engine load according to the intake pressure learning value.
(= K ′ / K) (Equation (b) of equation (14)), and a time differential value of the intake pressure obtained with respect to the engine speed from the iso-air quantity map given as a map in advance (Equation c of (14)) )
By multiplying the above by K0, a target time differential value of the intake pressure (the term (a) of the equation (14)) can be obtained without depending on the engine aging for each engine load.

Next, the end determination routine of step 121 in FIG. 5 will be described with reference to FIG. Since the control during deceleration is a control during deceleration, that is, from when the idle switch is turned off to on until the target idle engine speed Ne is reached, the engine speed Ne changes | Ne of the target idle engine speed Ne. When the state where -Ne0 | is equal to or less than the predetermined value continues for the predetermined time or more, the control at the time of deceleration is determined to have reached the target idle engine speed Ne and reached.

First, at step 500, the engine speed Ne taken in every calculation during deceleration and the engine speed Ne0 taken in the previous calculation are read. And step 5
Unit time of engine speed Ne at 01 (100 ms)
The change amount per contact ΔNe = | Ne−Ne0 | is calculated.

Thereafter, in step 502, it is determined whether ΔNe is equal to or smaller than a predetermined value K10 (the amount of change is small). Predetermined value K
If it is 10 or more (large change), the counter CNT is set to "0" in step 503, and since the counter COUNT is equal to or less than the predetermined value K20 in step 505, it is determined that the end condition is not satisfied, and the process goes to step 509.

On the other hand, if it is determined in step 502 that ΔNe is equal to or smaller than the predetermined value K10 (the amount of change is small), the counter CNT is incremented by “1” in step 504.
Next, at step 505, the counter COUNT is set to a predetermined value K2.
If 0 or less, the termination condition is not satisfied and the routine proceeds to step 509. In step 505, the counter CNT is set to a predetermined value K20.
If it is determined that the above condition is satisfied (the state of ΔNe ≦ K10 continues for a predetermined time or more), it is determined that the engine speed Ne has approached the target idle speed and the termination condition has been satisfied in step 506, and NISCMODE = 7.

Thereafter, in step 507, a learning value DISCLRN (air amount required during stable idling) of the ISC control amount corresponding to each engine load is read. Then, in step 508, the control at the time of deceleration is completed with the control amount DISC = DISCLRN. In step 509, the engine speed Ne taken in this time is stored in Ne0 for the next calculation.

GLRN of steps 202 to 204 in FIG.
1 to GLRN3 are set in the control subsequent to step 124 in FIG. 3 (during rotation feedback control). Hereinafter, the next control subroutine will be described with reference to FIG.

Steps 700 to 702 are routines for setting the control amount DISC so that the engine speed Ne becomes the target speed NT set according to the engine state such as the water temperature. First, at step 700, it is detected whether or not the engine speed Ne is lower than the target speed NT. If the engine speed Ne is lower than the target speed NT, the process proceeds to step 701. In step 701, the control amount DIS
C is the control amount DISC set at the previous control timing.
A predetermined amount ΔG is added to 0, and the process proceeds to step 703. On the other hand, if the engine speed Ne is equal to or higher than the target speed NT in step 700, the process proceeds to step 702. In step 702, the control amount DISC is subtracted by a predetermined amount ΔG from the control amount DISC0 set at the previous control timing, and the process proceeds to step 703.

Steps 703 to 707 are a routine for detecting the load state of the engine 1. Step 7
At 03, the condition of the air conditioner and the electric load is detected. If the air conditioner and the electric load are both off, the process proceeds to step 704. In step 704, the flag MODE2
Is set to “1”, and the process proceeds to step 708. Here, the flag MODE2 indicates the load state of the engine 1. In step 705, the state of the air conditioner is detected.
If the air conditioner is on, the process proceeds to step 706. At step 706, the flag MODE2 is set to "2", and the routine proceeds to step 708. On the other hand, if the air conditioner is off at step 705, that is, if only an electric load is applied to the engine 1, the process proceeds to step 707. In step 707, the flag MODE2 is set to "3", and the flow advances to step 708.

Step 708 is a routine for setting the learning control amounts GLRN1, GLRN2, and GLRN3 according to the load state. This learning control amount setting routine is shown in FIG.
This will be described based on the flowchart shown in FIG.

At step 800, it is detected whether or not the content of the flag MODE2 is equal to the content of the flag MODE21 at the previous control timing. Here, the flag MO
DE2 and the flag M at the previous control timing
If the content of the ODE 21 is different, the process proceeds to step 801. At step 801, the counter C1 is reset (C1 =
0) and proceed to step 802. Here, the counter C1
Is for measuring the duration time from the current load state. In step 802, the counter C2 is reset (C2 = 0), and this control ends. Here, the counter C2 is for measuring the duration of the current control amount DISC.

On the other hand, in step 800, the flag MODE2
And MODE of the flag at the previous control timing
If the contents of the contents are the same, the process proceeds to step 803. In step 803, the counter C1 is counted up by "1", and the process proceeds to step 804. In step 804, it is detected whether or not the value of the counter C1 is equal to or more than a predetermined value K1, that is, whether or not a predetermined time has elapsed since the current load state.
Here, when the value of the counter C1 is less than the predetermined value K1, the present process is terminated.

If the value of the counter C1 has reached the predetermined value K1 in step 804, the flow advances to step 805. In step 805, it is detected whether or not the control amount DISC is equal to the control amount DISC0 at the previous control timing.
If the control DISC is different from the control amount DISC0 at the previous control timing, the process proceeds to step 806. In step 806, the counter C2 is reset (C2 =
0) and proceed to step 808. On the other hand, step 805
If the control amount DISC is equal to the control amount DISC0 at the previous control timing, the process proceeds to step 807. In step 807, the counter C2 is counted up by "1", and the process proceeds to step 808.

At step 808, it is detected whether or not the value of the counter C2 is equal to or greater than a predetermined value K2, that is, whether or not a predetermined time has elapsed since the present control amount DISC. here,
If the value of the counter C2 is less than the predetermined value K2, the process ends. If the value of the counter C2 is equal to or more than the predetermined value K2 in step 808, the process proceeds to step 809.

Steps 809 to 812 are a routine for updating the learning control amount. At step 809, it is detected whether or not the flag MODE2 is "1". Here, when the flag MODE2 is “1”, the process proceeds to step 810. In step 810, the learning control amount GLRN1 corresponding to the load state where neither the air conditioner nor the electric load is input.
Is updated to the current control amount DISC, and this processing ends.
If the flag MODE2 is not “1” in step 809, the process proceeds to step 811. At step 811, it is detected whether or not the flag MODE2 is "2". If the flag MODE2 is "2", the process proceeds to step 812. In step 812, the learning control amount GLRN2 corresponding to the load state in which the air conditioner is input is changed to the current control amount DI.
SC, and the process ends. Step 811
And the flag MODE2 is not "2", that is, the flag M
If ODE2 is “3”, the flow proceeds to step 813.
In step 813, the learning control amount GLRN3 corresponding to the load state in which only the electric load is input is changed to the current control amount DI.
SC, and the process ends.

Returning to FIG. 11, the next step 709 is to set the learned intake pressures PLRN1, PLRN2, PRN according to the load condition.
This is a routine for setting the LRN3. The learning intake pressure setting routine will be described with reference to the flowchart shown in FIG. First, at step 900, the contents of the flag MODE2 and the flag MODE2 at the previous control timing are set.
It is detected whether or not the content of 1 is equal. If the content of the flag MODE2 is different from the content of the flag MODE21 at the previous control timing, step 901 is executed.
Proceed to. At step 901, the counter C3 is reset (C
3 = 0), and the process proceeds to step 902. Here, the counter C3 is for measuring the duration time from the current load state. In step 902, the counter C4 is reset (C4 = 0), and this control ends. here,
The counter C4 is for measuring the duration of the current intake pressure.

On the other hand, in step 900, the flag MODE2
And MODE of the flag at the previous control timing
If the contents of the contents are the same, the process proceeds to step 903. In step 903, the counter C3 is counted up by "1", and the process proceeds to step 904. In step 904, it is detected whether or not the value of the counter C3 is equal to or greater than a predetermined value K3, that is, whether or not a predetermined time has elapsed since the current load state.
Here, when the value of the counter C3 is smaller than the predetermined value K3, the present process is terminated.

If it is determined in step 904 that the value of the counter C3 is equal to or larger than the predetermined value K3, the process proceeds to step 905. At step 905, it is detected whether or not the intake pressure Pmr is equal to the intake pressure Pmr0 at the previous control timing. If the intake pressure Pmr is different from the intake pressure Pmr0 at the previous control timing, the process proceeds to step 906. At step 906, the counter C4 is reset (C4 = 0).
Then, the process proceeds to step 908. On the other hand, at step 905, the intake pressure Pmr and the intake pressure Pm at the previous control timing are determined.
If r0 is equal, the process proceeds to step 907. In step 907, the counter C4 is counted up by "1", and the process proceeds to step 908.

At step 908, it is detected whether or not the value of the counter C4 is equal to or greater than a predetermined value K4, that is, whether or not a predetermined time has elapsed since the present intake pressure Pmr. Here, when the value of the counter C4 is less than the predetermined value K4, the present process is terminated. Also, at step 908, the value of the counter C4 is
If it is four or more, the process proceeds to step 909.

Steps 909 to 913 are a routine for updating the learned intake pressure. At step 909, it is detected whether or not the flag MODE2 is "1". Here, when the flag MODE2 is “1”, the process proceeds to step 910. In step 910, the learned intake pressure PLRN1 corresponding to the load state where neither the air conditioner nor the electric load is input.
Is updated to the current intake pressure Pmr, and this processing ends.
If the flag MODE2 is not "1" in step 909, the process proceeds to step 911. At step 911, it is detected whether or not the flag MODE2 is "2". Here, when the flag MODE2 is “2”, the process proceeds to step 912. In step 912, the learned intake pressure PLRN2 corresponding to the load state in which the air conditioner is input is changed to the current intake pressure Pm.
r, and the process ends. If the flag MODE2 is not "2" in step 911, that is, if the flag
When DE2 is “3”, the process proceeds to step 913. In step 913, the learned intake pressure PLRN3 corresponding to the load state in which only the electric load is input is changed to the current intake pressure Pmr.
And the process ends.

As described above, in this embodiment, the target intake pressure Pt corresponding to the engine speed Ne is obtained from the constant air amount map, and the time differential value DELPT of the intake pressure Pt and the time differential value DELPMR of the actual intake pressure Pmr are obtained. Is equal to or smaller than I in feedback control having a proportional term and an integral term.
A so-called PI control for controlling the SC valve 6 (actuator) is performed (step 40 in FIG. 8).
5,406). As a result, not only the term proportional to the difference between the target intake pressure change and the actual intake pressure change but also the product of the deviation is reflected in the control amount, so the proportional gain can be reduced,
Excessive control can be prevented. Therefore, in the control using only the proportional element shown in FIG.
As shown by 0, the hunting is also eliminated in the engine speed by matching the intake pressure with the intake pressure uniquely obtained from the equal air amount curve with respect to the engine speed without excessively increasing or decreasing the control amount by the PI control. In this way, the engine speed can be made to match the target value while preventing hunting.

Further, when the time differential value DELPMR of the actual intake pressure is inverted from negative to positive (timing t3 in FIG. 14), the feedback control is started, so that the calculation start point can be reliably recognized. You can do it. In other words, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 3-258949, the equation of state of gas

[0099]

(Equation 13) Therefore, utilizing the fact that dPmr <0 when Gin <Gout, the time differential value DELPMR of the actual intake pressure is used.
Is positive (DELPMR ≧ 0) as a deceleration correction amount calculation start point. In this case, as shown in FIG. 14, the calculation start point is erroneously recognized in rapid racing or deceleration after a short step. Would. However, by starting the correction amount calculation at the time of deceleration when the time differential value DELPMR of the actual intake pressure reverses from negative to positive as in the present embodiment, the calculation start point can be reliably recognized.

Further, the time differential value DELPT of the target intake pressure obtained from the relationship between the engine speed and the intake pressure when the engine intake air amount is constant is corrected by the intake pressure during idling. Steps 403 and 404 in FIG. 8), it is possible to prevent the isometric air amount line from deviating from the air amount necessary for maintaining the idling due to the aging of the engine.

[0101]

As described in detail above, according to the present invention,
It provides an excellent effect that the engine speed can be matched with the target value while preventing hunting.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an engine auxiliary air amount control device of an embodiment.

FIG. 2 is a diagram showing an electrical configuration of an engine auxiliary air amount control device.

FIG. 3 is a flowchart illustrating an operation.

FIG. 4 is a flowchart illustrating an operation.

FIG. 5 is a flowchart for explaining an operation.

FIG. 6 is a flowchart for explaining an operation.

FIG. 7 is a flowchart for explaining an operation.

FIG. 8 is a flowchart for explaining the operation.

FIG. 9 is a flowchart for explaining the operation.

FIG. 10 is a flowchart for explaining the operation.

FIG. 11 is a flowchart illustrating an operation.

FIG. 12 is a flowchart illustrating an operation.

FIG. 13 is a flowchart for explaining the operation.

FIG. 14 is a time chart for explaining the operation.

FIG. 15 is a schematic diagram of an intake system of the engine.

FIG. 16 is a diagram showing an equal air amount curve.

FIG. 17 is a diagram showing an equal air amount curve.

FIG. 18 is a diagram for obtaining a correction coefficient.

FIG. 19 is a time chart.

FIG. 20 is a time chart.

FIG. 21 is a schematic diagram of an intake system of an engine for explaining a conventional technique.

FIG. 22 is a time chart for explaining the related art.

FIG. 23 is a schematic diagram of an intake system of an engine for explaining a conventional technique.

FIG. 24 is a diagram for explaining a conventional technique.

FIG. 25 is a time chart for explaining the related art.

FIG. 26 is a time chart for explaining the related art.

FIG. 27 is a diagram corresponding to claims.

[Description of Signs] 1 Engine 3 Throttle valve 5 Auxiliary air passage 6 ISC valve as actuator 8 Pressure sensor as intake pressure detecting means 23 Crank angle sensor as engine speed detecting means 24 CPU as actuator controlling means 27 Storage means Bu-RAM 31 as a suction pipe

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 41/00-41/40

Claims (1)

(57) [Claims] An auxiliary air passage that bypasses a throttle valve provided in an intake pipe of an engine and guides auxiliary air from an upstream of the throttle valve to a downstream of the throttle valve; and an auxiliary air passage that is provided in the auxiliary air passage. An actuator for adjusting the flow rate, an intake pressure detecting means for detecting the intake pressure, an engine speed detecting means for detecting the engine speed, and a constant engine intake air amount when shifting from the non-idle state to the idle state. Storage means for storing the relationship between the engine speed and the intake pressure at the time, and obtaining a target intake pressure corresponding to the engine speed by the engine speed detection means using the data of the storage means, The actuation is performed by feedback control having a proportional term and an integral term so that the derivative value and the time derivative value of the intake pressure by the intake pressure detecting means match. And an actuator control means for controlling the eta, said actuator control means, the time of the target intake pressure
An auxiliary air amount control device for an engine, wherein a differential value is corrected by an intake pressure at the time of idling .