JP3572368B2 - Engine idle speed learning control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine idle speed learning control device.
[0002]
[Prior art]
Conventionally, an automobile engine is provided with an auxiliary air control valve in an auxiliary air passage that bypasses a throttle valve in an intake passage, and compares an actual idle speed with a target idle speed during idle operation, and according to the comparison result. Thus, the opening degree of the auxiliary air control valve is controlled to feedback control the idle speed.
[0003]
Then, based on a feedback control amount (particularly, an increase / decrease amount) that is increased / decreased for the feedback control of the idle speed under a predetermined learning condition, the amount of change (clogging amount) of the leaked air amount when the throttle valve is fully closed is determined. A corresponding learning correction amount is set, and the correction is performed based on the learning correction amount, thereby performing more advanced learning control.
Further, in the learning control, in order to prevent erroneous learning, the absolute value of the learning correction amount is limited to a certain range, or as described in Japanese Patent Application Laid-Open No. 61-210248, one update per learning is performed. The amount is limited.
[0004]
[Problems to be solved by the invention]
However, in such a conventional engine idle speed learning control device, even if the absolute value of the learning correction amount is limited to a certain range, the range is limited to the amount of leaked air due to clogging of the throttle valve and the like. Since it must be wider than the range of change, there is no way to prevent erroneous learning within that range.
[0005]
Further, even if the amount of update per learning is limited, if erroneous learning continues, it cannot be prevented from accumulating and causing the learning correction amount to become an abnormal value.
Therefore, the conventional limiting method has a problem in that it is not possible to completely prevent the engine speed from rising and falling (and even engine stall) due to erroneous learning.
[0006]
In the present invention, in view of such a conventional problem, a change due to a clogged throttle valve or the like is generally a gradual change such that a slight change is recognized in one trip (from ON to OFF of the engine key switch). In view of the above, it is an object of the present invention to further appropriately limit the update of the learning correction amount, and to more completely prevent the engine speed from rising or falling due to erroneous learning.
[0007]
[Means for Solving the Problems]
Therefore, in the invention according to claim 1, in an engine having an auxiliary air control valve in an auxiliary air passage that bypasses a throttle valve in an intake passage, a means as shown in FIG. Constitute.
That is, a feedback control amount setting means for comparing the actual idle speed with a predetermined target idle speed during idling operation, and increasing or decreasing the feedback control amount according to the comparison result, and a rewritable storage for storing a learning correction amount. Learning correction amount storage means, control amount calculating means for calculating a control amount for the auxiliary air control valve based on the feedback control amount and the learning correction amount, and the auxiliary air control based on a signal corresponding to the control amount. Auxiliary air control valve driving means for driving the valve to open and close is provided.
[0008]
A learning correction amount updating unit that updates a learning correction amount of the storage unit in a direction to decrease the deviation based on a deviation between the feedback control amount and a predetermined target feedback control amount; Update limiting means is provided for limiting the update so that the new learning correction amount is within a predetermined range with respect to the learning correction amount when the engine key switch is turned on.
[0009]
Generally, the change due to the clogging of the throttle valve or the like is a gradual change such that a slight change is recognized in one trip (from ON to OFF of the engine key switch).
Therefore, when updating the learning correction amount, the updating amount is limited so that the new learning correction amount is within a predetermined range with respect to the learning correction amount when the engine key switch is turned on, thereby limiting the updating amount per trip. By doing so, the learning correction amount can be restricted within the range considered from the actual clogging of the throttle valve and the like, and erroneous learning can be reliably prevented.
[0010]
In the invention according to claim 2, the learning correction amount updating means sets an average value of the feedback control amount to ISCIave and a target feedback control amount to ISCIset,
The learning correction amount ISCLRC is
ISCLRC = ISCLRC + (ISCIave−ISCIset) / β
(However, β is an update rate constant, β ≧ 1)
It is characterized by being updated by
[0011]
In the invention according to claim 3, the update restricting means includes means for setting an upper limit value and a lower limit value by adding and subtracting a predetermined value to and from the learning correction amount when the engine key switch is turned on, and Means for comparing the new learning correction amount with the upper limit when updating, and limiting the upper limit when the learning correction amount is exceeded, and comparing the new learning correction amount with the lower limit when updating the learning correction amount and setting the lower limit And means for limiting to a lower limit when the number exceeds the limit.
[0012]
The invention according to claim 4 is characterized in that the addition value for setting the upper limit value and the subtraction value for setting the lower limit value have different sizes.
[0013]
【The invention's effect】
According to the first aspect of the present invention, when the learning correction amount is updated, the amount of update per trip is limited. Therefore, the learning correction amount can be restricted within a range that can be considered from the actual clogging of the throttle valve and the like. Can be reliably prevented, so that an effect of more completely preventing the engine speed from rising or falling due to erroneous learning can be obtained.
[0014]
According to the second aspect of the present invention, by adding and updating the predetermined ratio (1 / β) of the deviation between the average value of the feedback control amount and the target feedback control amount, temporary erroneous learning within the limit range is performed. Even if there is, the effect that the influence can be minimized can be obtained.
According to the third aspect of the invention, an effect is obtained that the upper limit and the lower limit of the learning correction amount can be appropriately limited.
[0015]
According to the fourth aspect of the invention, the effect that the restriction in the clogging increasing direction and the restriction in the clogging decreasing direction can be set separately according to the clogging characteristic of the throttle valve is obtained.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 2 is a system diagram of one embodiment.
A throttle valve 3 is provided in an intake passage 2 of the engine 1, and an auxiliary air passage 4 that bypasses the throttle valve 3 is provided. In the auxiliary air passage 4, an electromagnetic auxiliary air control valve 5 is provided. Is equipped.
[0017]
The auxiliary air control valve 5 is driven by a duty signal that changes the ON time ratio (duty) within a certain period, and the opening increases as the duty increases and decreases as the duty decreases. Therefore, the duty (%) here corresponds to the control amount.
The intake passage 2 is provided with an electromagnetic fuel injection valve 6 for each cylinder to supply fuel.
[0018]
Signals are input to the control unit 7 for controlling the operation of the auxiliary air control valve 5 and the fuel injection valve 6 from various sensors and switches.
Specifically, a crank angle sensor 8 that outputs a signal at each predetermined crank angle of the engine 1 is provided, so that the crank angle can be detected and the engine speed N can be calculated.
[0019]
Further, an air flow meter 9 for detecting an intake air flow rate Q in the intake passage 2, a throttle sensor 10 for detecting an opening TVO of the throttle valve 3, and a water temperature sensor 11 for detecting an engine cooling water temperature Tw are provided.
In addition, although not shown, signals from an engine key switch, a vehicle speed sensor, and the like are input to the control unit 7.
[0020]
Here, the microcomputer in the control unit 7 controls the control amount (duty) to the auxiliary air control valve 5 in accordance with the routine shown in FIGS.
Further, a basic fuel injection amount Tp = K · Q / N (K is a constant) is calculated from the intake air flow rate Q and the engine speed N, and various corrections are performed on the basic fuel injection amount Tp to obtain a final fuel injection amount Ti = Tp · COEF (COEF is various correction coefficients including an air-fuel ratio feedback correction coefficient) is set, and at a predetermined timing synchronized with engine rotation, a drive pulse signal having a pulse width corresponding to Ti is output to the fuel injection valve 6. Then, the fuel is injected.
[0021]
The duty control routine of FIG. 3 will be described. This routine is executed every predetermined time.
In step 1 (indicated as S1 in the figure, the same applies hereinafter), it is determined whether or not an idle speed feedback control condition (ISC condition) is satisfied.
Here, the ISC conditions are at least when the throttle valve 3 is fully closed (TVO = 0), the vehicle speed VSP is equal to or less than a predetermined value, and the start switch is OFF, and the engine is idling.
[0022]
If it is not the ISC condition, steps 2 and 3 are executed.
In step 2, the target feedback control amount ISCIset is retrieved from the actual water temperature Tw detected by the water temperature sensor 11 with reference to a table in which the target feedback control amount ISCIset is determined according to the engine cooling water temperature Tw.
Then, in step 3, the feedback control amount ISCI = ISCIset is set.
[0023]
In the case of the ISC condition, steps 4 to 8 are executed.
In step 4, the actual engine speed (idling speed) N is detected based on the signal from the crank angle sensor 8.
In step 5, the target idle speed Nset is searched from the actual water temperature Tw detected by the water temperature sensor 11 with reference to a table in which the target idle speed Nset is determined according to the engine cooling water temperature Tw.
[0024]
In step 6, the actual idle speed N and the target idle speed Nset are compared. If N <Nset, the feedback control amount ISCI is increased by a predetermined integral ΔI in step 7. Conversely, if N> Nset, in step 8, the feedback control amount ISCI is reduced by a predetermined integral ΔI.
Here, steps 4 to 8 correspond to feedback control amount setting means.
[0025]
After setting the feedback control amount ISCI, steps 9 to 11 are executed.
In step 9, the learning correction amount ISCLRC stored in the rewritable RAM as the learning correction amount storage means is read. The learning correction amount ISCLRC corresponds to a change in the amount of leaked air (clogging) when the throttle valve 3 is fully closed. A backup power supply circuit is used for the RAM in order to store and hold the learning correction amount ISCLRC even after the engine key switch is turned off.
[0026]
In step 10, the control amount (duty) ISCON is calculated by adding the feedback control amount ISCI and the learning correction amount ISCLRC as in the following equation. This part corresponds to the control amount calculating means.
ISCON = ISCI + ISCLRC
In step 11, a duty signal corresponding to the control amount (duty) ISCON is output to drive the auxiliary air control valve 5 to open and close. This part corresponds to the auxiliary air control valve driving means.
[0027]
Next, the learning routine of FIG. 4 will be described. This routine is executed every predetermined time or every predetermined rotation.
In step 21, it is determined whether or not the engine key switch is turned on (OFF → ON). When the engine key switch is turned on, the learning correction amount ISCLRC stored and held is read in step 22 and the next step 23 The upper limit value A and the lower limit value B are set by adding and subtracting predetermined values L1 and L2 to the learning correction amount ISCLRC when the engine key switch is turned on as in the following equation. This part corresponds to the upper limit value and lower limit value setting means.
[0028]
A = ISCLRC + L1
B = ISCLRC-L2
In step 24, it is determined whether a predetermined learning condition is satisfied.
Here, the predetermined learning condition is at least during idling operation and feedback control of the idle speed is being performed. Further, in order to learn in a stable state, the condition may be such that the air conditioner is turned off.
[0029]
If the predetermined learning condition is not satisfied, this routine ends. If the predetermined learning condition is satisfied, the process proceeds to step 25 and subsequent steps.
In step 25, the current feedback control amount ISCI is fetched, and the average feedback control amount ISCIave is calculated by the following equation.
ISCIave = [ISCIave · (α−1) + ISCI] / α
(However, α is an averaging ratio constant, α> 1)
In step 26, the target feedback control amount ISCIset is determined from the actual water temperature Tw detected by the water temperature sensor 11 by referring to a table (used in step 2) in which the target feedback control amount ISCIset is determined according to the engine cooling water temperature Tw. Search for.
[0030]
In step 27, a deviation ΔISCI between the average feedback control amount IScav and the target feedback control amount ISCIset is calculated by the following equation.
ΔISCI = ISCave−ISCIset
In step 28, a new learning correction amount ISCLRC is set by adding a predetermined ratio (1 / β) of the deviation ΔISCI to the current learning correction amount ISCLRC as in the following equation.
[0031]
ISCLRC = ISCLRC + (ISCIave−ISCIset) / β
(However, β is an update rate constant, β ≧ 1)
In step 29, the new learning correction amount ISCLRC is compared with the upper limit value A, and if ISCLRC> A, the process proceeds to step 30, where the learning correction amount ISCLRC is limited to A. This portion corresponds to the upper limit value limiting means.
[0032]
In step 31, the new learning correction amount ISCLRC is compared with the lower limit value B, and if ISCLRC <B, the process proceeds to step 32, where the learning correction amount ISCLRC is limited to B. This part corresponds to the lower limit value limiting means.
In step 33, the data of the learning correction amount ISCLRC on the RAM is rewritten with the newly set learning correction amount ISCLRC.
[0033]
The rewritten data of the learning correction amount ISCLRC corresponds to the amount of change in the leaked air amount (clogging amount) when the throttle valve 3 is fully closed, and correction is made based on this from the next time. Further, based on this, the degree of deterioration can be self-diagnosed.
In the present invention, when the learning correction amount ISCLRC is updated, the update per trip is limited by limiting the update so that the new learning correction amount is within a predetermined range with respect to the learning correction amount when the engine key switch is turned on. Limiter processing is performed to limit the amount. Generally, a change due to a throttle valve clogging or the like is a gradual change such that a slight change is recognized in one trip. Therefore, by limiting the update amount per trip, a learning correction amount ISCLRC is set. Can be restricted within a range considered from actual clogging of the throttle valve and the like, and erroneous learning can be reliably prevented.
[0034]
In addition, when setting the upper limit value A and the lower limit value B by adding and subtracting predetermined values L1 and L2 to the learning correction amount ISCLRC when the engine key switch is turned on, the magnitude of the addition value L1 and the subtraction value L2 is set. By making the lengths different, it is possible to separately set the restriction in the clogging increasing direction and the restriction in the clogging decreasing direction in accordance with the clogging characteristics of the throttle valve.
[0035]
That is, since the amount of clogging usually increases with deterioration, it is better to make L1 larger than L2. However, if the throttle valve portion is cleaned during maintenance and inspection work or the like, the clogging changes abruptly in the direction of decreasing clogging. In this case, the learning correction amount should be initialized. In the case of initialization, it is preferable that ISCLRC is set to a value slightly larger than 0, rather than 0, so that stalling due to initial friction can be prevented although there is some blow-up.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing the configuration of the present invention. FIG. 2 is a system diagram showing an embodiment of the present invention. FIG. 3 is a flowchart of a duty control routine. FIG. 4 is a flowchart of a learning routine.
DESCRIPTION OF SYMBOLS 1 Engine 2 Intake passage 3 Throttle valve 4 Auxiliary air passage 5 Auxiliary air control valve 6 Fuel injection valve 7 Control unit 8 Crank angle sensor 9 Air flow meter 10 Throttle sensor 11 Water temperature sensor

Claims (4)

In an engine having an auxiliary air control valve in an auxiliary air passage that bypasses a throttle valve in an intake passage,
Feedback control amount setting means for comparing the actual idle speed and a predetermined target idle speed during idle operation, and increasing or decreasing the feedback control amount according to the comparison result.
Rewritable learning correction amount storage means for storing a learning correction amount;
Control amount calculating means for calculating a control amount for the auxiliary air control valve based on the feedback control amount and the learning correction amount,
Auxiliary air control valve driving means for driving the auxiliary air control valve to open and close by a signal corresponding to the control amount;
A learning correction amount updating unit that updates a learning correction amount of the storage unit in a direction to decrease the deviation based on a difference between the feedback control amount and a predetermined target feedback control amount;
Update limiting means for limiting the update so that the new learning correction amount is within a predetermined range with respect to the learning correction amount when the engine key switch is turned on when updating the learning correction amount;
An engine idle speed learning control device configured to include: The learning correction amount updating means sets the average value of the feedback control amounts to ISCIave and the target feedback control amount to ISCIset,
The learning correction amount ISCLRC is
ISCLRC = ISCLRC + (ISCIave−ISCIset) / β
(However, β is an update rate constant, β ≧ 1)
2. The engine idle speed learning control device according to claim 1, wherein the engine speed is updated by: The update restricting means includes:
Means for setting an upper limit value and a lower limit value by adding and subtracting a predetermined value to and from a learning correction amount when the engine key switch is turned on;
Means for comparing the new learning correction amount with the upper limit value when the learning correction amount is updated, and for limiting the upper limit value when the learning correction amount is exceeded,
Means for comparing the new learning correction amount with the lower limit value when the learning correction amount is updated, and limiting the learning correction amount to the lower limit value when the lower limit value is exceeded;
The idle speed learning control device for an engine according to claim 1 or 2, wherein: The engine idle speed learning control device according to claim 3, wherein the addition value for setting the upper limit value and the subtraction value for setting the lower limit value are different in magnitude.

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