JPH04116240A - Intake air quantity controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent decrease in responsiveness of feedbacking by setting a control parameter to a specified value when an output duty ratio to an intake control valve is maximum, and a relation in intensity between a real current and target current flowing to a solenoid coil is inverted. CONSTITUTION:A target current for adjusting an intake control valve V to a specified opening from an operational condition of an internal combustion engine E is calculated, a standard duty ratio corresponding to the target current is calculated so as to determine an output duty ratio DOUT from the standard duty ratio and specified control parameter. Current feedback control which increases and decreases the control parameter, that is, the output duty ratio DOUT is performed based on the difference between a real current IACT and the target current which passes through a solenoid coil S so that the real current IACT is collected to the target current. In this case, when the output duty ratio DOUT becomes 100%, and the intensity of the real current IACT and the target current is inverted the control parameter is set to a specified value. Consequently, the overshoot of the real current IACT is prevented so as to improve responsiveness of current feedback control.

Description

Detailed Description of the Invention A9 Object of the Invention (I) Industrial Application Field The present invention provides an intake control valve in the intake passage of an internal combustion engine, and allows a predetermined duty current to flow through a solenoid coil of the intake control valve. The present invention relates to an intake air amount control device for an internal combustion engine that obtains an intake air amount of .

(2) Conventional technology Conventionally, it has been possible to control the intake air amount of an internal combustion engine by passing current through a solenoid-operated intake control valve installed in the intake passage of the internal combustion engine and adjusting the opening degree of the intake control valve. It is being done. At this time, the opening characteristics of the intake control valve are as follows:
It is determined by the current flowing through that solenoid coil.

By the way, the solenoid coil of the intake control outlet valve is driven by an electronic control device at a predetermined duty ratio, and its average current is equal to the product of the duty ratio and the special current flowing through the solenoid coil, and it is not affected by fluctuations in battery voltage or ,
It varies depending on individual differences in the excitation circuit (resistance and inductance of transistors and solenoid coils, etc.). Therefore,
In order to prevent the valve opening characteristics of the intake control valve from changing due to such causes, the actual current flowing through the solenoid coil is detected and compared with the target current that should be passed through the solenoid coil, and the duty for the solenoid coil is adjusted so that the two match. A method of increasing/decreasing the ratio ('GL flow shift feedback control) has been proposed (for example, see Japanese Patent Laid-Open No. 61-53437).

In addition, as another method of current feedback, instead of immediately increasing or decreasing the duty ratio based on the comparison result between the actual current and the target current, a control variable is provided intermediately, and this control variable is increased or decreased, resulting in an increase or decrease in the duty ratio. There are several possible methods.

Output duty ratio = Control variable * Basic duty ratio In this method, the output duty ratio is set according to the normal internal combustion engine operating condition (the battery voltage is about 14V) and the average intake control valve characteristics (the inductance of the solenoid coil, the winding resistance, etc.). The average (basic) duty ratio is memorized in advance (
(open loop control), fluctuations in battery voltage, individual differences in intake control valves, etc. are absorbed by the current feedback control. Therefore, unlike the method described in the above-mentioned publication, which performs feedback control on all control variables, this method provides a control variable close to the target value in advance in an open loop, so the burden of feedback is small.
Convergence is improved.

(3) Problems to be Solved by the Invention For example, when the battery voltage changes due to the load of the starter motor when starting an internal combustion engine, the duty ratio is adjusted using the current feedback to bring the actual current closer to the target current. However, especially when starting an internal combustion engine at low temperatures when the battery voltage tends to drop, if you try to provide the relatively large amount of opening of the intake control valve required at startup, the duty ratio will be 100%. In such a case, the current cannot actually be increased any further, but the electronic control unit calculates the control variable to a predetermined upper limit value (for example, 9.0%) in an attempt to increase the current. 0).

However, when the internal combustion engine is started and the load on the starter motor is removed, the battery voltage, which had been decreasing until then, increases to a normal value. As a result, the actual current now exceeds the target current, so the control variable is decreased in order to reduce the actual current.

By the way, at this time, the control variable has increased to the upper limit value, so it takes time for the control variable to decrease to a value suitable for normal battery voltage after startup, and during that time, the responsiveness of the actual current decreases. This problem arises.

The present invention has been made in view of the above-mentioned circumstances, and prevents the actual current flowing through the solenoid coil of the intake control valve from overshooting and reducing feedback responsiveness when the voltage suddenly changes. An object of the present invention is to provide an intake air amount control device for an internal combustion engine.

B1 Structure of the invention (I) Means for solving the problem In order to achieve the above object, the present invention provides an intake control valve in the intake passage of an internal combustion engine, as shown in FIG. 1 which is a diagram corresponding to the claims, means for determining a target current for the intake control valve from the operating state of the internal combustion engine in order to obtain a predetermined amount of intake air by passing a duty current through the solenoid coil of the intake control valve; means for determining the ratio; means for determining an output duty ratio for the intake control valve based on the basic duty ratio and a predetermined control variable; means for detecting the actual current flowing through the solenoid coil; and current feedback means comprising means for increasing or decreasing the control variable according to the comparison result of the comparison means, and the current feedback means causes the actual current to converge to the target current. The intake air amount control device sets the control variable to a predetermined value when the output duty ratio is maximum and the magnitude relationship between the actual current and the target current determined by the comparing means is reversed. The invention is characterized by further comprising means for.

(2) Effect According to the feature of the present invention described above, when a target current for adjusting the intake control valve to a predetermined opening is determined from the operating state of the internal combustion engine, the basic duty ratio corresponding to the target current is determined. Further, the output duty ratio is determined from the basic duty ratio and a predetermined control variable. Then, current feedback control is performed to increase or decrease the control variable, that is, the output duty ratio, based on the difference between the actual current flowing through the solenoid coil of the intake control valve and the target current, so that the actual current converges to the target current. At this time, when the output duty ratio reaches 100% and the magnitudes of the actual current and target current are reversed, the control coefficient is set to a predetermined value. This prevents overshoot of the actual current and improves the responsiveness of the current feedback control.

(3) Examples Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 2 is an overall configuration diagram of an air amount control device according to an embodiment of the present invention. A well-known intake control valve (2) is provided for controlling the idling speed by adjusting the amount of intake air passing through the passage. The intake control valve V includes a solenoid coil S for driving the valve body to open and close, and the degree of opening thereof is determined according to the value of the current flowing through the solenoid coil S.

A sensor group Se such as a cooling water temperature sensor for detecting the operating state of the internal combustion engine E is connected to the electronic control unit U. Further, a resistor R for detecting the actual current IAC flowing through the solenoid coil S is connected in series with the solenoid coil S, and the voltage across the resistor R is applied via an amplifier A and an A/D converter C. and is input to the electronic control unit U. By supplying a duty signal from the electronic control unit U to the base terminal of the chopping transistor Tr connected in series to the solenoid coil S, the current flowing through the solenoid coil S is controlled.

Next, the main flow of the present invention will be explained based on the flowchart of FIG.

When the output signal of the sensor group Se is read in order to detect the operating state of the internal combustion engine E in step S1, the target air amount Q corresponding to the operating state is determined in step S2.

That is, the amount of air to be supplied to the internal combustion engine E via the intake control valve (2) is calculated. In the ROM of the electronic control unit U,
A function (
(see graph) is stored, and the target air amount Q is calculated in step S2 based on the function in step S3.

Target current corresponding to 1. eND is calculated. Further, the ROM of the electronic control unit U stores a function (see graph) that provides the relationship between the current flowing through the solenoid coil S and the duty ratio of the base current of the chopping transistor Tr necessary for causing the current to flow. In step S4, the basic duty ratio DC1 corresponding to the target current ICa1l calculated in step S3 is calculated based on the function.
Next, in step S5, the actual current I Act flowing through the solenoid coil S is read through the resistor R1 amplifier A and the A/D converter C.

Initial flag F, which will be described in detail later, in step S6
The state of IIIa is determined and the initial flag FI
If NIT is 0, the actual current! 1
□ and target current 1 cso are compared. Then, in step S8, based on the comparison result, the current gain G a is set in order to converge the actual current Iact to the target current 1 eNll.
i Ia I L N is calculated by the following equation.

G a t * I L where k is a proportionality constant (for example, 0.0625), G, and positive n1LP are the previous gain.

Next, as will be described in detail later, in step S9 it is checked whether the gain G a in is within an allowable range, and in step S10 the output duty ratio D is determined based on the following formula.
o u L is calculated.

I) oat=Gm1y+ILH'' On the other hand, if the initial flag F111 is 1 in step S6, the gain G1.I is initialized in step Sll instead of step S7.8 based on the following equation.

When the output duty ratio □ is calculated in this way, a duty current corresponding to the output duty ratio D6□ is supplied to the chopping transistor Tr, so that the solenoid coil of the intake control valve ■ The current flowing through S is feedback controlled. Therefore, the target air amount Q is applied to the internal combustion engine E.

In order to supply the air, the opening degree of the intake control valve (2) is controlled to a predetermined value.

Next, based on the flowchart of FIG. 4, the gains G, 1. ．． Checking and setting the initial flag FINIT will be explained.

In step S21, the current gain G * i n I L
If H exceeds the gain upper limit value G, 8, □ (for example, 8.92), the previous gain CII i is determined in step S22.
,, I L P is the gain upper limit value G Air+MAM
replaced by On the other hand, even if the answer is NO in step S21, the current gain G*i s l is determined in step S23.
If L)II is less than the gain lower limit value Gm1allIN (for example, 0.0), the previous gain GsimILP is replaced with the gain lower limit value G, 10, in step S24. Also, step S21,
23, this time the gain CII i n l L H is the gain upper limit value G. mNAM and lower gain limit G Ili++MI
If it is between N, the previous gain G□n1LP is replaced with the current gain G a i n +I in step S25.

In this way, the gain G111. When the upper and lower limits of l are limited, in subsequent steps S26 to S30, an inversion flag F representing the magnitude relationship between the target current ICHD and the actual current IAC is set.

That is, in step S26, the inversion flag F_INV is set to 1.
(in the case of r c,, ≧I ACT), and if target current 1 c14D≧actual current I ACT is not established in step S27, the inversion flag FINV is set in step S2B.
is taken to be 0. On the other hand, in step S26, the inversion flag Ft
Nw is O (if I CHD < I act)
, and in step S29, target current I CM11≧actual current! 1. If a is established, the inversion flag F is set in step S30.
INV is set to 1. In any of the above cases, the inversion flag FINV changes from 1 to 0 or from 0 to 1.
This means that it has been reversed. Thus the target current I,. If the magnitude relationship between the actual current IAeT and the actual current IAeT is reversed, and the output duty ratio Dou has reached 100% in the next step S31, the initial flag FIIT is set to 1 in a step S32. , As explained in step Sll of FIG. 3, the current gain G m i , , I
Iga I ACT/I c. is initialized to the value of .

On the other hand, if YES in step S26 and step S
If there is YES/S in step S27, or N in step S26.
O, and No in step S29, that is, if the inversion flag F INV remains 1 or 0 and the magnitude relationship between the target current I COD and the actual current I Act is not inverted, the initial flag F INV is set in step S33. engineering,
T is set to 0, and the current flowing through the solenoid coil S is feedback-controlled by increasing/decreasing the current gain Ga1fiILN as explained in step S7.8 of FIG.

Note that even if the magnitude relationship between the target current ICHD and the actual current IAC is reversed (step 328.30),
In step S31, the output duty ratio D Ou L is 10.
If it does not reach 0%, initial flags FIN, T
is also set to O.

Next, calculate the output duty ratio based on FIGS. 5 and 6. A failsafe system using the utO value will be explained.

In step S41 of FIG. 5, the output duty ratio is determined. If uL is greater than or equal to the upper limit L□ (I00%), in step 342, the function (see Figure 6) that gives the characteristics of the battery power supply voltage and target current ICMEI stored in the ROM is set. Based on the maximum reference target current ICM□
, H are searched. Then, in step S43, the target current 1 CMEI is changed to the maximum reference target current I CNDF! H
If the target current I is below, that is, the target current I. If □ exceeds 100% compared to the output duty even though is small, the timer is counted in step S44,
Furthermore, when 5 seconds have passed in this state in step S45,
It is determined that a disconnection has occurred in the solenoid coil C, and the failure flags FF and IL are set to 1 in step S46. Furthermore, even if the answer in step S43 is NO,
Actual current I flowing through solenoid coil S in step S47
If ACT is less than the minimum reference actual current IACTFSL, a failure flag FFAIL is set to 1, indicating that a disconnection has occurred in the signal line for detecting disconnection of the solenoid coil C. On the other hand, if both steps S43 and 47 are NO, or if the count time of the timer does not exceed 5 seconds in step S45, the timer is reset in step 34B, and the failure flag FFAIL is set to 0 in step S49. cents.

The output duty ratio is determined in step S41. If uL is less than the upper limit value DLALNN (I00%), in step S50 the target current ICM my minimum reference target current I
If it is less than CMDFSL, it is assumed that the state is normal and the process moves to step 348. However, step S
At 50, the target current I COD is the minimum reference target current ICM□
, L or more, and the output duty ratio is determined in step S51. . is less than the lower limit value DLAL, 4L (0%), that is, the output duty ratio D05. is less than 0%,
It is determined that there is a possibility that the chopping transistor Tr has an ON failure, and the process moves to step S44. Incidentally, in the case of NO in step S51, the process moves to step 347 to confirm the disconnection of the signal line for detecting the disconnection of the solenoid coil S.

Note that when performing failure detection as described above, the gain G
Output the initial of M in as the duty ratio Dout
If performed only under the condition of ≧100%, the gain G*
= Output duty ratio D when n is initialized
Since the condition of a u t ≧ 100% is canceled,
Failure detection becomes impossible. However, as in the present invention, the output duty ratio Dout≧100% and the actual current ■, 6. If the gain G*iF is initialized when the magnitude relationship between the target current ICMfl and the target current ICMfl is reversed, it becomes possible to improve the responsiveness of current feedback and perform fault diagnosis at the same time.

Next, the intake air amount control will be explained in more detail based on FIG. 7, taking as an example the time of starting the internal combustion engine E.

When starting the internal combustion engine E, especially when starting from a low water temperature, it is necessary to open the intake control valve ■ to increase the amount of intake air in order to improve the startability. Target current ■ to be supplied to solenoid coil C of intake control valve ■ until NCI is reached, that is, until internal combustion engine E starts. , has a relatively large value. On the other hand, the terminal voltage of the battery, which is approximately 12V when the internal combustion engine E is stopped, decreases due to the load of the starter motor as soon as the starter switch is turned on, and particularly decreases significantly when the water temperature is low. As a result, the target current I C,D
Since a deviation occurs between the actual current I ACT and the actual current I ACT, the gain G1.7 is increased from 1.0 to the upper limit value 9.0 in order to converge the actual current I ACT to the target current I CMfl. The above gain G□. In the process of increasing, if the output duty ratio D o u L reaches 100%,
The actual current IAC is unable to converge to the target current ICHD, and remains in the state of target current 1c, 4D>actual current 1Ac7.

Now, when the internal combustion engine E starts, the load on the starter motor disappears and the generator starts operating, causing the battery terminal voltage V to rise rapidly to about 14V, while the required amount of intake air decreases. Target current IC
M. decreases. As a result, the actual current I ACT rises to exceed the target current I CKD, so it becomes necessary to reduce the gain G1, 7 from the upper limit value 9°0.

However, in a normal control system, the gain G1,7 and the output duty ratio. Since uL decreases slowly as shown by the broken line, the actual current IAC□ exceeds the target current IC)ID and overshoots as shown by the broken line.
This has the disadvantage that its convergence is reduced. In order to prevent such inconveniences, this control device adjusts the output duty ratio. ,, when t is maximum and the magnitude relationship between the actual current I ACT and the target current ICN is reversed, the gain G m
= a to about 1.0 (= I ACT / T CN
D) is initialized. As a result, the gain G 11
Ia and output duty ratio. □ quickly decreases, and the actual current I ACT can be quickly converged as shown by the solid line.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various small design changes can be made without departing from the scope of the invention described in the claims. Is possible.

For example, although the embodiment has been described with respect to the time when the internal combustion engine E is started, the present invention is applicable to intake air amount control in all operating ranges of the internal combustion engine E.

C1 Effects of the Invention As described above, according to the present invention, the output duty ratio is changed by increasing/decreasing the control variable in order to converge the actual current flowing through the solenoid coil of the intake control valve of the internal combustion engine to the target current. In a device that performs current feedback control, when two drastic responses of the control variables are required due to sudden changes in the situation, that is, when the output duty ratio is 100%.
and when the magnitude relationship between the actual current and the target current is reversed, the control variable is forcibly set to a predetermined value.

Therefore, even in a normal control system in which the control variable responds only at a normal speed, it is possible to improve the responsiveness of the current feed hack control depending on the situation.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is an overall configuration of an intake air control device according to an embodiment of the present invention, Fig. 3 is a flowchart showing its main flow, and Fig. 4 is a flowchart showing a gain check. FIG. 5 is a flowchart explaining the setting of the initial flag, FIG. 5 is a flowchart explaining the fail-safe mechanism, FIG. 6 is a graph showing the relationship between battery terminal voltage and actual current, and FIG. 7 is a time chart when starting the internal combustion engine. . M, . . . means for determining the target current ICMIll, M2.
・Means for determining the basic duty ratio D c+tn, M,
. . . Means for determining the output duty ratio D out , M4 . . . Means for determining the actual current I ACT, M5-.
・Means for increasing/decreasing the control variable, M6...gain Ga
l Means for increasing or decreasing h, M7... Current feedback means, M6... Means for setting control variables, E... Internal combustion engine, ■... Intake passage, S... Solenoid coil pipe V...・Intake control valve N2 flash Figure 6

Claims (1)

[Claims] An intake control valve (V) is provided in the intake passage (I) of the internal combustion engine (E), and a predetermined intake is controlled by passing a duty current through the solenoid coil (S) of the intake control valve (V). Means (M_1) for determining the target current (I_C_M_D) for the intake control valve (V) from the operating state of the internal combustion engine (E) in order to obtain the air amount.
From this target current (I_C_M_D), the intake control valve (V)
means (M_2) for determining a basic duty ratio (D_C_M_D) for the intake control valve (V); M_3) and the actual current (I_A_
C_T), a means (M_4) for detecting this actual current (I_
A_C_T) and the target current (I_C_M_D); a comparison means (M_5) for comparing the target current (I_C_M_D); and a current feedback means (M_6) for increasing or decreasing the control variable (G_a_i_n) based on the comparison result of the comparison means (M_5).
M_7) and; The current feedback means (M_7) converts the actual current (I_A_C_T) into the target current (I_C
_M_D), the intake air amount control device is configured such that the output duty ratio (D_o_u_t) is maximum, and the actual current (I_
An intake air amount control device for an internal combustion engine, further comprising means (M_8) for setting the control variable (G_a_i_n) to a predetermined value when the magnitude relationship between the target current (A_C_T) and the target current (I_C_M_D) is reversed.