JP3784628B2 - Engine idle speed control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an idle speed control device that controls the amount of intake air to an engine so that the engine speed in an idle state becomes a target value.
[0002]
[Prior art]
As this type of prior art, Japanese Patent Application Laid-Open No. 62-195430 discloses an “engine idle speed control device”. In the device disclosed in this publication, when the engine shifts from an idle state to a non-idle state. The control amount of the idle speed control valve (ISC valve) is attenuated over time. This eliminates a so-called breathing phenomenon caused by a sudden decrease in the intake air amount when shifting to the non-idle state.
[0003]
However, in the device of the above publication, the control amount of the ISC valve is attenuated at a predetermined rate with respect to the unit time, so the degree of attenuation of the control amount does not match the actual warm-up state of the engine, and the engine speed It is conceivable that the controllability deteriorates. In other words, when the engine is started, the degree of water temperature rise during non-idle differs depending on the water temperature at that time. The amount of intake air is reduced too much or the amount of reduction is insufficient. Further, adaptation is required to determine a constant for time decay, which causes problems such as an increase in the number of man-hours for design.
[0004]
In addition, the “throttle valve opening control device” disclosed in Japanese Patent Publication No. 2-26691 is disclosed, and in the device disclosed in the publication, every time the engine temperature reaches a predetermined value according to the engine state when not idling. In addition, the opening of the throttle valve is controlled to be reduced. As a result, when the engine returns from the running state to the idle state after the engine is started at a low temperature, an appropriate amount of air is supplied. Actually, the ratio of the output of the return pulse (control amount to the throttle valve closing side) with respect to the temperature rise is determined according to the engine water temperature when the accelerator is depressed from the idle state.
[0005]
However, the apparatus described in Japanese Patent Publication No. 2-26691 still has the following problems. That is, in the apparatus of the above publication, the water temperature threshold value for controlling the throttle valve to the closed side is determined immediately before the accelerator is depressed, and the lower the engine water temperature, the lower the water temperature threshold value is set (return pulse output). Is reduced). For this reason, if the engine becomes non-idle immediately after starting at a very low temperature and the non-idle state is continued and the engine warms up gradually, the water temperature threshold is set to the actual warm-up in a certain degree of warm-up. It will not fit the state. Therefore, the opening degree of the throttle valve does not match the engine warm-up state when returning from non-idle to idle, and the controllability of the rotational speed deteriorates. Also in this case, fine adaptation is required, which increases the design man-hours.
[0006]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above-mentioned problem, and its purpose is in the case where the feedback control of the idle speed is resumed after being interrupted, such as when returning from non-idle to idle. Another object of the present invention is to provide an engine idling engine speed control device capable of performing a suitable engine speed control suitable for the warm-up state of the engine.
[0007]
[Means for Solving the Problems]
In the idling engine speed control device of the present invention, the base air amount is calculated according to the warm-up state of the engine, and the deviation between the target engine speed and the actual engine speed when the idling engine speed feedback control condition is satisfied. Based on this, the air F / B amount is calculated. Then, the intake air amount to the engine is controlled in accordance with the base air amount and the air F / B amount so that the rotational speed in the idle state becomes the target value.
[0008]
In the first aspect of the invention, the ratio between the air F / B amount and the base air amount is calculated (air amount ratio calculating means). Then, when the feedback control condition shifts from satisfaction to failure, the ratio of the air F / B amount and the base air amount calculated immediately before is used. Thereafter, in the state where the condition is not satisfied, the air in accordance with the ratio is used. An F / B amount is set (air F / B amount setting means).
[0009]
In short, the base air amount changes according to the warm-up state of the engine and becomes smaller as the warm-up progresses. In this case, as described above, the ratio between the air F / B amount and the base air amount is used, and the air F / B amount and the base air amount are balanced by setting the air F / B amount according to this ratio. The air F / B amount is set while being always maintained. Therefore, after the feedback control condition is not satisfied, the air F / B amount changes according to the change in the base air amount, that is, the degree of warm-up of the engine. Therefore, when the feedback control condition is satisfied again and the idling speed control is resumed, the air F / B amount becomes commensurate with the warm-up state at that time, and the speed reaches the target immediately after the feedback control returns. It converges to the rotation speed. That is, it is possible to carry out a suitable rotational speed control that matches the warm-up state of the engine. In addition, unlike the above-described conventional device, the number of design steps can be reduced because no adaptation is required.
[0010]
Specifically, as described in claim 2, when the base air amount is a and the air F / B amount at the time when the feedback control condition is satisfied is b, the air F / B amount setting means provides feedback. Using the ratio “b / a” of the air F / B amount and the base air amount immediately before the control condition shifts from satisfaction to failure, the product of this ratio and the latest value QBASE of the base air amount,
QBASE x (b / a)
The air F / B amount may be set by In this case, when the feedback control condition is not satisfied, the air F / B amount required for the base air amount at that time can be easily calculated.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The apparatus of the present embodiment embodies an idle speed control device for suitably controlling the idling speed of an on-vehicle multi-cylinder engine, and applies the engine to the engine so as to converge the idling speed to a target value. Adjust the intake air volume. Hereinafter, an engine control device for realizing idle speed control will be described in detail.
[0012]
FIG. 1 is a configuration diagram showing an outline of an engine control apparatus according to the present embodiment. In FIG. 1, an intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. The intake pipe 2 is provided with a throttle valve 4, and the opening degree of the throttle valve 4 is controlled by driving a throttle actuator 5. The throttle valve 4 is provided with a throttle opening sensor 6, and the surge tank 7 of the intake pipe 2 is provided with an intake pressure sensor 8.
[0013]
A piston 10 is disposed in the cylinder 9, and a combustion chamber 13 above the piston 10 communicates with the intake pipe 2 and the exhaust pipe 3 via an intake valve 14 and an exhaust valve 15. The cylinder 9 (water jacket) is provided with a water temperature sensor 21 for detecting the cooling water temperature. The intake port 17 of the engine 1 is provided with an electromagnetically driven injector 18 for each cylinder. The injector 18 injects fuel (gasoline) supplied from a fuel tank (not shown). A spark plug 19 is disposed on the cylinder head 12. The rotation of a crankshaft (not shown) accompanying combustion is detected by a rotation speed sensor 20.
[0014]
The ECU 30 is mainly composed of a microcomputer including a CPU 31, a ROM 32, a RAM 33, a backup RAM 34, and the like. Each detection signal is input to the ECU 30 from the throttle opening sensor 6, the intake pressure sensor 8, the rotation speed sensor 20, the water temperature sensor 21, etc., and the ECU 30 determines the throttle opening, the intake pressure, Detects engine speed and engine water temperature.
[0015]
The CPU 31 performs various calculations according to the program in the ROM 32, calculates the optimal fuel injection amount, ignition timing, and intake air amount based on the engine operating state at that time, and controls the injectors 18 according to the control signals corresponding to the calculation results. The driving of the spark plug 19 and the throttle actuator 5 is controlled. In particular, the CPU 31 controls the intake air amount to the engine 1 by driving the throttle actuator 5 to adjust the opening degree of the throttle valve 4 so that the engine speed in the idle state becomes a target value.
[0016]
Next, details of idle speed control will be described. FIG. 2 is a flowchart showing a calculation procedure of an air control amount for idle speed control. This process is performed, for example, for each fuel injection of each cylinder (180 ° CA for a four-cylinder engine) or for every predetermined time. Is implemented.
[0017]
In FIG. 2, first, at step 101, the base air amount QBASE is calculated according to the water temperature Tw at that time. At this time, as the engine coolant temperature Tw is lower, a larger value is set as the base air amount QBASE. In the following step 102, it is determined whether or not the F / B condition for the idle speed is satisfied. When determining the F / B condition, it is determined mainly whether or not the engine is in the idle state. However, in addition, it may be determined whether or not the ignition timing F / B control is being performed as the engine speed falls, and if the ignition timing F / B control is being performed, a negative determination may be made in step 102.
[0018]
If the idle speed F / B condition is satisfied, the routine proceeds to step 103, where the air F / B amount QI is calculated based on the deviation between the engine speed Ne and the target speed Nt. In the following step 104, the ratio KQI of the air F / B amount QI to the base air amount QBASE is calculated (KQI = QI / QBASE). When the base air amount QBASE and the air F / B amount QI are calculated as described above, the throttle actuator 5 is driven based on the QBASE and QI. Accordingly, the intake air amount is adjusted, and as a result, the idle speed is controlled to the target value.
[0019]
On the other hand, if the F / B condition for the idling speed is not satisfied and the open control is performed, the process proceeds to step 105, and the air F / B amount QIOPN at the time of opening is calculated using the ratio KQI previously calculated in step 104. Is calculated. That is, the ratio KQI is multiplied by the base air amount QBASE calculated this time, and the product is set as the air F / B amount QIOPN at the time of opening (QIOPN = KQI · QBASE).
[0020]
Thereafter, in step 106, it is determined whether QI> 0 and QIOPN <QI. In subsequent step 107, it is determined whether QI <0 and QIOPN> QI. Steps 106 and 107 determine whether or not the air F / B amount QIOPN is changing in the direction of reducing the control amount. If any of steps 106 and 107 is YES, the process proceeds to step 108 and QIOPN. To update the air F / B amount QI (QI = QIOPN). In short, regardless of whether QI is positive or negative, QI update is permitted only when the absolute value of QIOPN decreases. In the present embodiment, step 104 corresponds to the “air amount ratio calculating means” of the present invention, and steps 105 and 108 correspond to “air F / B amount setting means”.
[0021]
Next, an outline of the idle rotation speed control will be described with reference to the time chart of FIG. FIG. 3 shows the behavior of the engine speed Ne and the transition of various control amounts when the engine is started.
[0022]
The engine speed Ne rapidly rises as the engine starts, reaches a peak speed, then turns down, and once falls below the target idling engine speed (target speed Nt) at time t1. The target rotational speed Nt is an idle rotational speed set according to the engine water temperature or the like, and as an example, Nt = 1200 rpm when the engine is cold started. The base air amount QBASE is set at any time according to the engine warm-up state (water temperature Tw).
[0023]
Further, at the time t1, the idling engine speed F / B control is started in order to converge the engine speed Ne to the target engine speed Nt. That is, the control amount corresponding to the deviation between the engine speed Ne and the target speed Nt is sequentially accumulated to calculate the air F / B amount QI. Then, based on the air F / B amount QI and the base air amount QBASE, an air control amount required for idle speed control is calculated, and the throttle actuator 5 is thereby driven.
[0024]
Thereafter, at time t2, for example, the accelerator pedal is depressed, and the engine speed Ne increases. At this time, since the state transitions from the idle state to the non-idle state, the F / B condition for the idle speed is not satisfied, and the open control is started. After time t2, the open air F / B amount QI (QIOPN) is calculated according to the ratio of the air F / B amount QI immediately before t2 and the base air amount QBASE ("QI1 / QBASE1" in the figure). In this case, the air F / B amount QI is set while the balance with respect to the base air amount QBASE is always maintained. That is, when the base air amount QBASE changes as shown in the figure as the engine warms up (changes in the water temperature Tw), the air F / B amount QI (QIOPN) gradually changes (attenuates) in accordance with the change.
[0025]
Thereafter, at time t3, the engine returns to the idle state again, and the F / B control of the idle rotation speed is resumed. At this time, the air F / B amount QI is commensurate with the warm-up state at time t3. ing. Therefore, the engine speed Ne converges to the target speed Nt immediately after the return of the F / B control. Accordingly, as indicated by a two-dot chain line in the figure, the air F / B amount QI is too large immediately after the return to idling, resulting in an increase in the engine speed Ne (circle numeral 1 in the figure) or the air F / B amount QI. The engine speed Ne will be low (circle numeral 2 in the figure), and there will be no inconvenience.
[0026]
According to the embodiment described in detail above, the following effects can be obtained.
When the F / B condition for the idling speed is not satisfied, the ratio of the air F / B amount QI and the base air amount QBASE just before that is used, and the air F / B amount QI according to the ratio at the time of open control thereafter. Therefore, when the F / B control of the idling engine speed is resumed, the air F / B amount QI corresponds to the warm-up state at that time. Therefore, the rotational speed converges to the target rotational speed immediately after the return of the F / B control, and suitable rotational speed control that matches the warm-up state of the engine can be performed. Further, the above apparatus does not require adaptation for control amount attenuation, and the design man-hour can be reduced.
[0027]
In addition to the above, the present invention can be embodied in the following forms.
In the above embodiment, the base air amount QBASE is calculated according to the water temperature Tw, but this is changed. For example, a learning value or a target rotational speed change correction term is added to the water temperature correction term based on the water temperature Tw, and the sum is used as the base air amount QBASE, or the elapsed time from the start of starting is added to the parameter for QBASE calculation. You may do it. The base air amount QBASE may be calculated according to the warm-up state of the engine, and the base air amount QBASE is calculated according to the cylinder wall temperature, the intake air temperature, etc. instead of the water temperature Tw. Also good.
[0028]
In the above embodiment, the throttle actuator is used to control the intake air amount during idle operation by electronically controlling the opening of the throttle valve. Instead of this, a throttle valve (so-called, An ISC valve) may be provided, and the intake air amount may be controlled by adjusting the opening of the throttle valve during idle operation. Also in this case, the above-described excellent effect can be obtained similarly.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of an engine control apparatus according to an embodiment of the invention.
FIG. 2 is a flowchart showing a calculation procedure of an air control amount for idle speed control.
FIG. 3 is a time chart showing an outline of idle speed F / B control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 30 ... ECU, 31 ... CPU.

Claims (2)

The base air amount is calculated according to the warm-up state of the engine, and the air F / B amount is calculated on the basis of the deviation between the target rotational speed and the actual rotational speed when the idle rotational speed feedback control condition is satisfied. In the idling engine speed control device that controls the intake air quantity to the engine in accordance with the base air quantity and the air F / B quantity so that the engine speed at the engine reaches a target value,
An air amount ratio calculating means for calculating a ratio between the air F / B amount and the base air amount;
When the feedback control condition shifts from satisfaction to failure, the ratio of the air F / B amount and the base air amount calculated by the air amount ratio calculation unit immediately before is used. Air F / B amount setting means for setting the air F / B amount according to
An engine idling speed control device comprising: When the base air amount is a and the air F / B amount at the time when the feedback control condition is satisfied is b, the air F / B amount setting means has the air F / B immediately before the feedback control condition shifts from satisfaction to failure. Using the ratio “b / a” between the B amount and the base air amount, the product of this ratio and the latest value QBASE of the base air amount,
QBASE x (b / a)
The engine idle speed control device according to claim 1, wherein the air F / B amount is set by the engine.

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