JPS59165844A - Feedback control method for idling speed of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent occurrence of engine stall by reducing gradually the aux. air amount from the amount corresponding to the fully opened state of a control valve at the starting time of feedback control for the idling speed, and thereby smoothing the change of the number of engine revolutions. CONSTITUTION:When it is judged (Step 3) that the engine is in cranking state, the open valve duty ratio DOUT of a control valve is set to 100% to supply much mixture gas to the engine. When a specific time tIU has passed since commencement of cranking, the process is proceeded to Step 10 so as to start the feedback control of the iding number of revolutions. In this feedback control, the aux. air amount is gradually substracted from the amount corresponding to the fully opened state of control valve. Thereby the change of the revolving speed of engine can be smoothed to ensure prevention of generation of engine stall.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the idle speed bulk pack of an internal combustion engine, and more particularly to a method for controlling the idle speed feedback to ensure stable idle operation immediately after starting the engine.

In an internal combustion engine, when an electrical load such as a headlight, an air conditioner, etc. or a mechanical load is applied to the engine during idling operation, the load on the engine increases, the idling speed decreases, and engine stall is likely to occur. For this reason, conventionally, a target idle speed is set according to the engine load condition, the difference between this target idle speed and the actual engine speed is detected, and the system is adjusted according to the size of the difference so that this difference becomes zero. An idle speed feedback control method is known in which the engine speed is controlled to be maintained at a target idle speed by supplying auxiliary air to the engine.

In such an idle speed feedback control method, the engine load increases not only when the electrical load and mechanical load described above but also when the engine cooling water temperature is low. especially,
Immediately after a cold start, the engine temperature is low and the lubricating resistance of the sliding parts increases, which increases the engine load.In addition, it is difficult to ensure complete combustion of the air-fuel mixture, so the engine speed at idle decreases. tends to become unstable. Further, immediately after starting the engine, the battery consumed by the starter operation during cranking is charged by the generator, so the operation of the generator becomes a load on the engine, which tends to cause the idle speed to become unstable. In order to avoid this instability of the idle speed, for example, the auxiliary air amount control valve should be fully opened for a predetermined period of time after the engine speed exceeds the cranking speed when the engine is started. After setting the idle speed to a higher speed than the target engine speed, the engine is warmed up by shifting to feedback control that controls the engine speed to the target engine speed, and the battery voltage is A method for recovery has been proposed by the present applicant (Japanese Patent Application No. 57-077250).

However, in such a method, when transitioning from operation in complete explosion mode to idle operation after the predetermined time has elapsed, the amount of auxiliary air is reduced from the amount corresponding to the fully open state of the control valve to a lower engine speed than in complete explosion mode. In order to rapidly reduce the engine speed to an amount commensurate with the target engine speed, the engine speed is suddenly reduced. Moreover, this sudden decrease in engine speed not only gives discomfort to the driver, but also causes the driver to feel uncomfortable when the engine speed decreases. If the voltage cannot be restored sufficiently, the alternator will still be in full power generation state even after the complete explosion mode, and the load of the alternator will continue to be applied to the engine, so the engine speed at the time of the transition will be lower. Despite the above conditions, the amount of auxiliary air is increased by feedback control when the engine speed decreases only when the engine speed falls below the target engine speed. There is a risk that the supply of auxiliary air will be delayed and the engine will stall.

The present invention has been made in view of the above points, and provides a control valve that adjusts the amount of auxiliary air supplied to the engine through an air passage that opens downstream of the throttle valve in the intake passage of an internal combustion engine and communicates with the atmosphere. In an idle rotation speed feedback control method that controls according to the difference between an actual engine rotation speed and a target engine rotation speed at idle, the control valve is operated for a predetermined period of time after the engine exits a cranking state at the time of engine startup. The idle rotation speed feedback control is started immediately after the predetermined period of time has elapsed, and the feedback control is started to gradually reduce the amount of auxiliary air from the amount corresponding to the fully open state of the control valve, and complete explosion is achieved. An idle speed feedback control method that avoids driver discomfort due to a sudden decrease in engine speed when transitioning from mode operation to idle operation, and prevents the occurrence of engine stall based on the engine load state during this transition. The purpose is to provide.

Examples of the method of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram schematically showing the entire idle rotation speed feedback control device for an internal combustion engine to which the method of the present invention is applied. Reference numeral l indicates, for example, a four-cylinder internal combustion engine, and the engine 1 includes: An intake passage 3 with an air cleaner 2 attached to its open end is connected to an exhaust passage 4. A throttle valve 5 is disposed inside the intake passage 3, and an air passage 8 opens into the intake passage 3 downstream of the throttle valve 5 and communicates with the atmosphere.
is installed. An air cleaner 7 is attached to the open end of the air passage 8 on the atmosphere side, and an auxiliary air amount control valve (hereinafter simply referred to as "control valve") 6 is disposed in the middle of the air passage 8. This control valve 6 is a normally closed electromagnetic valve, and is composed of a solenoid 6a and a valve 6b that opens an air passage 8 when the solenoid 6a is energized. connected.

A fuel injection valve 10 is provided in the engine 1 of the intake passage 3 and the opening 8a of the air passage 8.
0 is connected to a fuel pump (not shown) and EC
Electrically connected to U9.

A throttle valve opening sensor 17 is connected to the throttle valve 5 and is connected to the intake passage 3.
An intake passage isolation pressure sensor 12 communicating with the intake passage 3 via a pipe 11 is located downstream of the opening 8a of the air passage 8, and an engine cooling water temperature sensor 13 and a rotation angle position sensor 14 are provided on the engine 1 body, respectively. installed, each sensor is E
It is electrically connected to CU9. Reference numeral 15 indicates an electrical device such as a headlight, and this electrical device 15 is electrically connected to the ECU 9 via a switch 16. Further, reference numeral 18 indicates a starter, and a starter switch 19
It is electrically connected to the ECU 9 via.

Next, the operation of the idle rotation speed feedback control device configured as described above will be explained.

Respective engine operating state parameter signals are supplied from the throttle valve opening sensor 17, absolute pressure sensor 12, water temperature sensor 13, engine rotation angle position sensor 17, and starter switch 19 to the ECU 9, and the ECU 9 receives these engine operating state parameter signals. The engine operating state and the engine load state are determined based on the value and the electrical load state signal from the electrical device 15, and the engine 1 is
The fuel supply amount, that is, the opening time of the fuel injection valve lO, and the amount of auxiliary air, that is, the valve opening duty ratio of the control valve 6, are respectively calculated, and the fuel injection valve 10 and the control valve 6 are operated according to each calculated value. A control signal for activation is provided to each.

The solenoid 6a of the control valve 6 is energized over the valve opening duty ratio according to the calculated value, opens the valve 6b, and opens the air passage 8, so that a predetermined amount of air according to the valve opening duty ratio flows into the air passage 8. and is supplied to the engine 1 via the intake passage 3.

The fuel injection valve 10 is opened for an opening time according to the above-mentioned calculated value to inject fuel into the intake passage 3, and the injected fuel is mixed with the intake air and always maintains a predetermined air-fuel ratio (for example, stoichiometric air-fuel ratio). The air-fuel mixture is supplied to the engine 1.

When the opening time of the control valve 6 is lengthened to increase the amount of auxiliary air, the amount of air-fuel mixture supplied to the engine (2) increases, the engine output increases, and the engine speed increases. Conversely, control valve 6
If the valve opening duty ratio is shortened, the amount of air-fuel mixture supplied will decrease and the engine speed will decrease. By controlling the amount of auxiliary air, that is, the valve opening duty ratio of the control valve 6 in this way, the engine speed can be controlled.

Figure 2 is a diagram showing the circuit configuration inside the ECU 9 in Figure 1.
The engine angular position from the engine rotational angular position sensor 14 in FIG. At the same time, - is also supplied to the Ne counter 902. The Me counter 902 indicates the previous T from the engine rotation angle position sensor 14.
It counts the time interval from when the DC signal is input to when the current TDC signal is input, and the count Me value is proportional to the reciprocal of the engine rotation speed Ne. The Me counter 902 is
This count value Me is sent to the CPU 90 via the data bus 910.
Supply to 3.

The respective output signals from various sensors such as the throttle valve opening sensor 17, intake road absolute pressure sensor 12, and engine cooling water temperature sensor 13 shown in FIG. The signals are sequentially supplied to an A/D converter 906 by 905 . The A/D converter 906 sequentially converts the output signals from each sensor described above into digital signals and sends the digital signals to the data bus 910.
It is supplied to the CPU 903 via.

The on-off signals from switch 16 and starter switch 19 of electrical device 15 in FIG.
After the voltage is corrected to a predetermined voltage level, the data input circuit 91
3 is converted into a predetermined signal and sent to the CP via the data bus 910.
Supplied to U903.

The CPU 903 is further connected via a data bus 910 to a remote only memory (hereinafter referred to as rROMJ) 907, a random access memory (hereinafter referred to as rRAMJ) 908, and drive circuits 909 and 911.
08 temporarily stores calculation results etc. in the CPU 903,
The ROM 907 stores control programs and the like executed by the CPU 205.

The CPU 903 determines the engine operating state such as the starting state and the engine load state according to the various engine parameter signals described above according to the control program stored in the ROM 907, and determines the valve opening duty ratio DouT of the control valve 6 that controls the amount of auxiliary air. is calculated, and a control signal corresponding to this calculated value is supplied to the drive circuit 911, and the fuel injection valve 10
A control signal based on the calculated value is supplied to the drive circuit 909 via the data bus 910. The drive circuit 909 supplies the injection valve operator 0 with a drive signal for opening the fuel injection valve 10 in accordance with the control signal, and the drive circuit 909
Reference numeral 11 supplies the control valve 6 with a drive signal for turning the control valve 6 on and off based on the control signal.

3(,) to (c) are flowcharts showing the control procedure of the control valve 6 executed within the ECU 9, and the above-mentioned control procedure will be explained below with reference to FIG. 4.

This engine control program is executed by the ECUe shown in FIG.
After turning on the ignition switch (not shown in FIG. 1) and initializing the ECU 9 (step 1 in FIG. 3(a)), this is executed every time the TDC signal is generated. T from the rotation angle position sensor 14
When the DC signal is input to the ECU 9 (step 2), it is first determined whether the engine is in a cranking state (step 3).

This determination is made, for example, by determining whether or not the engine rotational speed is equal to or higher than a predetermined cranking rotational speed N e CR (for example, 400 rpm) and the starter switch 19 is on. If the determination result in step 3 is affirmative (YES), the process advances to step 4, that is, if the engine speed Ne is
When it is determined that the starter switch 19 is lower than CR (Sm in Fig. 4 (a)) and refluxing is in progress, the control valve 6 is fully opened to make the start easier and to quickly reach the idle speed. The valve opening duty ratio DouT of the control valve 6 is set to 100% so as to supply the air-fuel mixture to the engine l (Sm in FIG. 4(b), this is referred to as "control in complete explosion mode"). If the determination result is negative (NO) for the first time after starting, that is, does the engine speed Ne become equal to or higher than the cranking speed N e CR for the first time?
Sm) in FIG. 4(a) or when the starter switch 19 is turned off, only immediately after that, that is, only when the determination result in step 3 becomes negative for the first time, step 6 is executed and continues to be completed even after cranking is completed. The period tau for supplying the auxiliary air amount in the explosion mode is determined as described below. Next, it is determined whether or not a predetermined time tau has elapsed after the end of cranking (Step 7 in FIG. 3), and the valve opening duty ratio DOut of the control valve 6 continues to be 100% until the predetermined time tau has elapsed. (Step 4 in Figure 3(a)
). This predetermined time Iu is for stabilizing the combustion state immediately after starting, and since this time is changed depending on the engine temperature, the engine cooling water temperature sensor 13 at the time of engine starting
It is calculated based on a predetermined calculation formula using the water temperature signal from
The predetermined time t+u is set to become longer as the engine cooling water temperature decreases.

When a predetermined time tau has elapsed immediately after cranking, the process proceeds to step 8 (FIG. 3(b)), where a value MH proportional to the reciprocal of the target carrot rotational speed NH during idling is set. This value MH is set, for example, in accordance with the water temperature signal from the cooling water temperature sensor 13 and the magnitude of the engine load on the near conditioner, etc., so that the exhaust gas characteristics, fuel efficiency characteristics, etc. are optimized.

Next, the process proceeds to step 9, where it is determined whether or not the previous loop was in the complete explosion mode. This determination result is positive (YES)
In the case of , that is, when the previous loop was in complete explosion mode (4th
Sp +) in Figure (b), proceeding to step 1 (described in detail later), the calculation of the valve opening duty ratio DOut of the control valve 6 in this loop is based on the valve opening duty ratio set during control in the complete explosion mode of the previous loop. Ratio DouT(=10
0%) as the initial value (Sp in FIG. 4(b)). This step 9 is provided so that the engine speed does not suddenly decrease in steps due to the transition to the deceleration mode described later immediately after the completion of the complete explosion mode, and the amount of auxiliary air decreases rapidly.If step 9 is not provided, Immediately after executing step 8, the process proceeds to step 11, and control is performed in the deceleration mode of step 13 until Me≧MH is satisfied in step 11, that is, until the engine speed Ne becomes equal to or less than the upper limit value NH of the target engine speed. The valve opening duty ratio DouT of the valve 6 is calculated.

The calculation of the valve opening duty ratio DouT in this deceleration mode is performed using, for example, a duty ratio Dx set as a deceleration mode term and a duty ratio DE set as an electrical load term.
It is given as the sum of For example, the deceleration modes Dx maintain the engine speed Ne at the target engine speed NH when there is no electrical load such as the electrical device 15 and the engine water temperature is in an idling state at a predetermined value (for example, 70'C) or higher. The electric load term DE is set to a constant value corresponding to the amount of auxiliary air required to
This is a predetermined value that is set according to the on-off signal of Therefore, when the complete explosion mode is immediately shifted to the deceleration mode, the valve opening duty ratio Dou of the control valve 6 is as shown in Fig. 4 (
It decreases in a stepwise manner as shown by the broken line in b).

Along with this, the engine speed Ne suddenly decreases (broken line in FIG. 4(a)). The amount of auxiliary air is increased by feedback control despite the sudden decrease in engine speed when the engine speed Ne falls below the target engine speed N14. be. Depending on the engine load condition at this time, the engine speed drops sharply as indicated by the broken line in FIG. 4(a), leading to an engine stall.

If step 9 is provided, in the current loop immediately after the completion of the complete explosion mode, the process will proceed from step 9 to step 10 as described above, and the control M~ will be executed in the feedback mode, so in the next loop, the determination result of step 9 will be negative (No). Become. However, even if the engine speed Ne at this time is greater than the target engine speed NH, that is, even if the determination result in step 11 is negative (No), it is determined in step 12 that the previous loop was in the feedback mode, and step 10 Proceed to. Therefore, the feedback control continues without calculating the valve opening duty ratio D o u T in the deceleration mode (Fig. 4(, ), (b).
) Sp 10+).

The valve opening duty ratio DouT in the deceleration mode is calculated by fully closing the engine throttle valve 5 (Fig. 1) and changing the engine speed Ne from the high engine speed side to a predetermined engine speed (for example, ' + 50 Or pm). ) or less and the engine speed Ne is higher than the target engine speed No.

FIG. 3(c) is a flowchart detailing the calculation procedure of the valve opening duty ratio DouT of the control valve 6 calculated in the feedback mode of step 10 shown in flowchart I- of FIG. 3(b), The valve opening duty ratio DouT of the control valve 6 is calculated as the sum of feedback modes Dp+n and electric load term DE, which will be described later.

First, in step 100, the electrical load term DE is determined in the same manner as determined in the deceleration mode described above.

After that, it is determined whether the previous loop was in feedback mode or not (step 101), and the determination result is negative (NO).
), the process proceeds to step 102.

In step 102, it is determined whether the previous loop was in the complete explosion mode, and if it is in the complete explosion mode, that is, if the determination result is affirmative (YES), the feedback mode term Dp+n-1 value is set to 100%. (Step 10)
3). If the determination result in step 102 is negative (No), that is, if the aforementioned deceleration mode is to be shifted to the feedback mode, then in step 104 the feedback mode term Dp+n-1 value is set to the value of the aforementioned deceleration mode class Dx.

If it is determined in step 101 that the previous loop was in feedback mode (affirmative (YES)), step 1
In step 05, the Dp+n'l value, which will be described later, is set to the value of the feedback mode type DP+n set during the previous J sheep.

Next, in steps 106 and 107, the control amount for feedback control is calculated. In step 10G, it is calculated using a proportional-integral control term and a feedback control term. Find the feedback modes D p + 'n. The integral control term is the target engine speed N H and the actual engine speed Ne.
The proportional control term is obtained by multiplying the deviation ΔMn from the above deviation value by 1, and the constant value Kp. It is found by the product of The value obtained by adding the feedback control term Dp+n-1 obtained in steps 103 to 105 to the proportional/integral control term obtained in this way is set as the feedback mode class Dp+n for this loop, and the process proceeds to step 107, where the feedback control amount is The valve opening duty ratio DOLIT is determined as the sum of the feedback modes and the above-mentioned electric load term DE.

In this way, the valve opening duty ratio D immediately after the completion of the complete explosion mode is
outT sets the DpIn-1 value to 100%, and this Dp
Since the proportional control term ΔDp and the integral control term ΔD+ are added to the In-1 value, the valve opening duty ratio DouT is 1.
The engine speed gradually decreases from 00%, and the engine speed changes from the speed during operation in complete explosion mode to the target engine speed N.
It is possible to smoothly transition to H (Fig. 4 (a)
solid line).

Note that once the engine speed Ne is controlled to the target engine speed NH as described above, the battery electricity Vo
reaches the predetermined voltage V Bo and charging is completed.
), even if the alternator stops operating and the engine load is reduced, the valve opening duty ratio DouT is reduced by the amount of the load reduction through feedback control, and the engine speed is maintained at the target engine speed No. .

As described above, according to the idle speed feedback control method of the present invention, the control valve is kept fully open for a predetermined period of time after the engine exits the cranking state when the engine is started, and the control valve is kept fully open for a predetermined period of time. Immediately after, the idle speed feedback control is started, and the feedback control is started to gradually reduce the amount of auxiliary air from the amount corresponding to the fully open state of the control valve, so that the operation is changed from the complete explosion mode to the idle operation. It is possible to smooth the change in the engine speed when transitioning to the current state, avoid driver discomfort due to a sudden decrease in the engine speed during this transition, and prevent the occurrence of engine stall based on the engine load condition at this time. It can be prevented.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an internal combustion engine control device to which the idle speed feedback control method of the present invention is applied;
The diagram shows the electronic control unit (ECU) shown in Figure 1.
3(a) to (C) are program flowcharts showing the control procedure of the auxiliary air amount control valve shown in FIG. 1, and FIG. 4 is a timing chart of the control method when starting the engine. The figure (,) shows the engine speed at startup, and the figure (b) shows the change in the opening duty ratio D o u T of the auxiliary air amount control valve shown in Fig. 1. ) is a chart showing the state of the starter switch, and (d) of the same figure is a chart showing changes in battery voltage. 1... Internal combustion engine, 3... Intake passage, 5... Throttle valve, 6... Control valve, 8... Air passage, 9... Electronic control unit, Ne... Actual engine rotation NH... Target engine speed, tlu... Predetermined time, DouT... Valve opening duty ratio of the control valve. Applicant Honda Motor Co., Ltd. Agent Patent Attorney Toshihiko Watanabe Figure 3 (b) Figure 3 (C) F-guchi Town

Claims (1)

[Claims] 1. The control amount of the control valve that adjusts the amount of auxiliary air supplied to the engine through the air passage that opens downstream of the throttle valve in the intake passage of the internal combustion engine and communicates with the atmosphere is calculated based on the actual engine speed at idle and the target. In the idle speed feedback control method that controls according to the difference from the engine speed, the control valve is fully opened for a predetermined period of time after the engine exits the cranking state when starting the engine;
Immediately after the predetermined period of time has elapsed, the idle speed feedback control is started, and the feedback control is started so as to gradually reduce the amount of auxiliary air from the amount required to reach the fully open state of the control valve. Rotation speed feedback control method.