JPS63186948A - Ignition timing control method directly after start of internal combustion engine - Google Patents

Abstract

PURPOSE:To stabilize the operability at the time directly after start and at the time of idling, by prohibiting the feedback control of a bypass valve at the time directly after the start of an engine, and on the other hand by controlling the ignition timing in response to the engine speed detected value and the target idling speed. CONSTITUTION:To an intake pipe 12, a bypass passage 17 which bypasses a throttle valve 16 is connected, and to the bypass passage 17, an idling speed control valve 18 is arranged. And the pulse motor 18b of the control valve 18 is controlled by an FCU 20, thus the valve body 18a of the control valve 16 is driven. Further, to the ECU 20, signals from various sensors 31 through 34 which detect the operating conditions of an engine are input. In this case, until the lapse of a prescribed period of time from directly after the start of the engine, the feedback control of the control valve 18 is prophibited, and the valve is controlled so as to keep a prescribed opening. Further, the ignition timing is feedback-controlled in response to the engine speed detected value and the target idling speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling ignition timing immediately after starting an internal combustion engine.

(Prior art) The valve opening degree of a bypass valve (hereinafter referred to as "RLSC pulp") provided in a bypass passage that bypasses a throttle valve during idling operation of an internal combustion engine is adjusted to a detected engine speed value and a target idle speed. A control method (hereinafter referred to as rl
SC control) is known.

On the other hand, an internal combustion engine is equipped with an electronic ignition timing control device, and the ignition timing is adjusted according to parameters representing the engine speed and engine load, such as a parameter value A/N calculated from the intake air amount A and the engine speed N. A method of controlling ignition timing is known in which the ignition timing is set to an optimal value depending on the operating state. This ignition timing control method normally sets the ignition timing in an advanced direction as the engine speed increases, and in a retarded direction as the parameter value A/N increases. and,
The electronic ignition timing control 'a device is also used to control the engine speed during idle operation, and depending on the difference between the detected engine speed and the target idle speed, when the detected engine speed is higher than the target idle speed, Retard the ignition timing,
When the engine speed is low, the ignition timing is advanced to stabilize idle speed.

However, in both the above-mentioned ISC control and ignition timing control, the engine speed is not yet stable immediately after the internal combustion engine starts, so after the engine reaches a complete explosion state, the engine speed rises once. Thereafter, normal oven loop control is performed until the rotational speed drops to the target idle rotational speed or the vicinity thereof.

(Problems to be Solved by the Invention) However, when the above-described conventional control method is applied to an internal combustion engine with a large intake passage volume between the throttle valve and the intake valve, the engine speed increases immediately after the engine starts, and
After this revving, the engine speed drops significantly,
There is a problem that hunting may occur in some cases.

Fig. 4 explains such a problem, and shows that the conventional ISC control immediately after the engine starts and the ISC using ignition timing control J.
It shows changes over time in pulp valve opening, ignition timing, and engine speed. In order to improve the startability of the engine, the ISC pulp is kept fully open until the engine reaches a complete explosion state at time t1 in FIG. 4. The negative pressure in the intake road downstream of the throttle valve immediately after startup is the same as the negative pressure in the intake road during steady-state idling, because even if the throttle valve is fully closed, air has just begun to be supplied into the engine cylinder. Therefore, together with the fact that the ISC valve is fully opened, the engine speed N will rise rapidly (between time t1 and time t3 in tc+ in FIG. 4).

At this time, as the engine speed increases, the ignition timing control device advances the ignition timing toward the optimum ignition timing (see the peak in Figure 4). When the ignition timing is advanced, the engine speed increases, and when the ignition timing is retarded, the engine speed decreases.) The engine speed increases rapidly.

In order to make the engine speed quickly reach the target idle speed (fast idle speed), ISO control
The valve opening of the SC valve is rapidly closed at a predetermined valve closing speed from the time when a complete explosion state of the engine is detected until it reaches a predetermined valve opening (Fig. 4 (between time tl and t2 in al) After that, the valve is closed slowly at a speed slower than the predetermined valve closing speed until the target valve opening is reached (also from t2 to 4 in Fig. 4+al). In this way, the valve opening of the ISC valve is controlled. Then, the engine speed drops rapidly after time t3 in Figure 4, and further decreases across the target idle speed at time t4 in Figure 4. At this time, the change in engine speed N with respect to the change in intake fiA is larger, the parameter value A/N increases, and the ignition timing is set in the retarded direction (see Figure 4 fbl).Retarding the ignition timing acts in a direction that promotes a drop in engine speed. However, the engine speed drops further.

For example, the valve opening degree of the ISC valve is feedback-controlled according to the difference between the detected engine speed value and the target idle speed, starting from the 4th point in FIG. 4 when the engine speed crosses the target idle speed and decreases. If this is the case, the engine speed will eventually reach the target idle speed due to this feedback control, but if the engine speed rises or falls significantly as described above, hunting may occur.
There was a problem in that it took a long time to stabilize to the target idle speed.

In addition, in order to prevent the above-mentioned drop in engine speed and hunting, the opening degree of the ISC valve is gradually closed from time t1 when a complete explosion state is detected as shown in FIG. 4, and the target idle speed is reached. The problem is that it takes time to arrive.

The present invention was made to solve such problems, and it prevents the engine speed from rising or falling immediately after the engine starts, and furthermore from hunting, and also allows the engine speed to quickly reach the target idle speed after starting. An object of the present invention is to provide a method for controlling ignition timing immediately after the start of an internal combustion engine so as to stabilize the ignition timing.

(Means for Solving the Problems) In order to achieve the above-mentioned object, according to the present invention, a bypass passage that bypasses the throttle valve is connected to the intake passage of the internal combustion engine, and the bypass passage is connected to the intake passage of the internal combustion engine. Immediately after the internal combustion engine is started, a bypass valve is disposed in the internal combustion engine, and when the internal combustion engine is in an idling operating state, the opening degree of the bypass valve is feedback-controlled according to the detected engine speed value and the target idle speed. In this ignition timing control method, the feedback control of the bypass valve is prohibited until a predetermined period has elapsed from immediately after the start of the internal combustion engine, and the ignition timing is controlled to a predetermined valve opening, while the ignition timing is controlled based on the detected engine speed value and the target idle. Provided is a method for controlling ignition timing immediately after starting an internal combustion engine, which is characterized by performing feedback control according to the engine speed.

(Function) When the ignition timing is advanced near the idle speed, the engine speed increases, and when it is retarded, the engine speed decreases.

Immediately after the engine starts, the opening of the bypass valve is controlled to a predetermined valve opening by open-loop control, and the engine speed tends to rise rapidly after a complete explosion. Feedback control is performed according to the idle speed and the engine speed detection value, and by advancing or retarding the ignition timing, the engine speed is prevented from rising, dropping, hunting, etc.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 shows an ignition timing control device for an internal combustion engine that implements the method of the present invention, and reference numeral 10 in the figure indicates, for example, a four-cylinder gasoline engine.
is connected. An air cleaner 13 is attached to the end of the intake pipe 12 that is open to the atmosphere, and a Karman vortex type air flow sensor 14 that detects the air flow IA taken into the engine 10 is disposed. The electronic control unit (described later)
ECU) 20 and supplies an air flow rate detection signal to the electronic control unit 20.

A throttle valve 15 is disposed in the middle of the intake pipe 12, and a bypass passage 17 that bypasses the throttle valve 15 is connected to the intake pipe 12. One end of the bypass passage 17 is connected to the intake air upstream of the throttle valve 15 and downstream of the air flow sensor 14. The other end communicates with the pipe 12, and the other end communicates with the intake pipe 12 downstream of the throttle valve 15, respectively. An idle speed control valve (ISO valve) 18 is disposed in the middle of the bypass passage 17.

This ISC valve 18 consists of a valve body 18a that opens and closes the bypass passage 17, and a pulse motor 18b that is connected to this valve body 18a and controls the valve opening degree.
b is electrically connected to the output side of the electronic control unit 20, and controls the valve opening degree of the valve body 18a according to the number of drive pulse signals supplied from the electronic control unit 20. When the ISC valve 18 is opened, air passing through the bypass passage 17 and bypassing the throttle valve 15 is supplied to the engine 10.

An ignition plug 26 is attached to each cylinder 10a of the engine 10, and the ignition plug 26 is connected to the output side of the electronic control unit 20 via a distributor 24 and an evening knife device 22. The Eve knife device 22 generates a secondary high voltage using an ignition coil (not shown) based on an ignition control signal from the electronic control unit 20, and this high voltage is supplied to the distributor 24.
The fuel is sequentially supplied to the spark plugs 26 of each cylinder in a predetermined order to ignite the air-fuel mixture in the cylinder 10a.

Various sensors are attached to the input end of the electronic control unit 20, such as an idle switch 30 that detects the fully closed position of the throttle valve 15, and a camshaft (not shown) that detects the rotation angle (crank angle) θ of the engine 10. Crank angle sensor 31, engine coolant temperature T
A cooling water temperature sensor 32 that detects W, a vehicle speed sensor 33 that is attached to a speedometer cable (not shown) and detects vehicle speed, and a starter switch that detects the on/off state of a starter switch (key switch) that operates a starter motor (not shown). The sensors 34 etc. are connected respectively,
These sensors provide detection signals to the electronic control unit 20.

Next, the operation of the control device configured as described above will be explained with reference to FIGS. 1 and 3.

First, to explain the ISC control at the time of engine starting, the IS
The O valve 18 is kept fully open to ensure startability. For example, if the engine rotation speed is a predetermined rotation speed (for example, 450
When it is detected that the engine 10 has risen across rpI11), it is determined that the engine 10 has reached a complete explosion state. After the complete explosion state of the engine 10 is detected, the valve opening of the ISC valve 18 is set to a predetermined opening (for example, a valve opening that is larger than the target valve opening required to maintain the engine speed at the target idle speed NIDL). (from time 111 to time t13 in FIG. 1), the valve rapidly closes at a predetermined valve closing speed, and then the engine speed decreases until the target idle speed is reached (from time 111 to time t13 in FIG. 1). (from time tla to time tld in the figure), the valve is closed slowly at a predetermined speed smaller than the above-mentioned valve closing speed (valve closing speed from time tll to time tla in Figure 1),
After the target idle speed is reached, the opening degree of the ISC valve 18 is feedback-controlled according to the deviation between the detected engine speed and the target idle speed. In this way, the valve opening degree of the ISC valve 18 is determined from the start of the engine 10 until the engine speed once exceeds the target idle speed and then drops across the target idle speed (from time t10 in FIG. 1). tld), feedback control is prohibited and oven loop control is performed at a predetermined valve opening.

On the other hand, control of the ignition timing by the ignition timing control device is executed according to the procedure shown in FIG.

The idle stabilization ignition timing control program shown in FIG.
The ignition timing θ until a complete explosion state is detected is set to a predetermined value θsr (constant value) that is optimal for starting the engine 10.

When a complete explosion state is detected, the electronic control unit 20
First, in step 40 of FIG. 3, it is determined whether the idle switch 30 is outputting an on signal (or the throttle valve 15 is fully closed). This discrimination result is negative (
In the case of NO), that is, when the throttle valve 15 is not fully closed, the engine 10 is in a state other than the state in which it should be idle, and in this case, the execution of the idle stabilization ignition timing control program is terminated.

If the determination result in step 40 is affirmative (Yes), subsequent steps 41 and 42 are executed to determine whether or not the idle stabilization ignition timing control may be executed. That is, in step 41, it is determined whether the vehicle equipped with the engine 10 is stopped, and in step 42, it is determined whether the coolant temperature Tw detected by the coolant temperature sensor 32 is equal to or higher than a predetermined value. If the engine 10 is not stopped, it is determined that the engine 10 is not in a state immediately after starting and there is no need to stabilize the idle rotation by ignition timing control, and if the cooling water temperature TW is below a predetermined value, ignition timing control is performed when the engine is cold. Execution of the program is ended in order to execute the program.

If the determinations in steps 42 and 43 are both affirmative, the process proceeds to step 43, and the starting start time t (for example, 7
(seconds) or less. When the engine 10 leaves the idle state, the engine speed reaches a predetermined value Nmax (for example,
If the engine speed exceeds 1300 rpm), it is not necessary to execute this idle stabilization ignition timing control program and the program may be terminated, but the engine speed may exceed this predetermined value when the engine speed rises immediately after starting. Therefore, if the program is terminated when the engine speed increases, it is inconvenient that the idle speed cannot be stabilized. Therefore, the determination in step 43 is made to avoid such inconvenience, and if the predetermined time t has not elapsed (the determination result is affirmative), the determination of the engine rotation speed, which will be described later, is performed in step 44. Instead, the process proceeds to step 46, where calculation of ignition timing by idle stabilization ignition timing control is executed. On the other hand, when the predetermined time t has elapsed (if the determination result in step 43 is negative), the process proceeds to step 44, where it is determined whether the engine rotation speed Ne is equal to or less than the predetermined value Nmax. If this determination is affirmative, the ignition timing calculations from step 46 onward are continued. If the determination result in step 44 is negative, it is not necessary to execute the idle stabilization ignition timing control as described above, and the program ends.

In step 46, the engine rotation speed Na is calculated based on the detection signal of the crank angle sensor 31. The crank angle sensor 31 generates a crank angle position signal every time it detects a predetermined crank angle position, and supplies this to the electronic control unit 20.
0, the engine rotation speed Ne is calculated from the input time interval of the input crank angle position signal.

Next, the electronic control unit 20 sets the target idle rotation speed N1° based on the engine coolant 17w detected by the coolant temperature sensor 32. (step 47), this target idle rotation speed Nl0L is determined by the engine cooling water 17w.
The rotation speed is set to the minimum rotation speed that allows the engine 10 to operate stably and independently. Then, this set target idle rotation speed N,. , and the engine rotational speed Ne detected in step 46, and then calculate the ignition timing (steps 48 and 49). There are various methods of calculating the ignition timing correction value θIIIL. For example, the following formula +11 and (
2) calculates the ignition timing correction value θIOL and the ignition timing θ.

θIOL −K ・(NIDL −Ne) =K ・Δ
N... (1) θ = θ8. +θ+ o L
--(2) Here, K is a proportional control constant, θ, is the basic ignition timing set according to engine speed Ne, engine load parameter value A/N, engine cooling water temperature Tw, etc. θ is set to a positive value on the advance side with reference to the top dead center of the compression stroke. As can be seen from the above equation, when the engine speed detection value Ne is smaller than the target idle speed NIIIL, the ignition timing correction value θIOL is set to a positive value according to its deviation ΔN, and the ignition timing θ is set to the basic ignition timing. θ most.

It is set to the more advanced angle side. In addition, the engine rotation speed detection value N
8 is larger than the target idle rotation speed NIDL, it is set to the retarded side in accordance with the deviation ΔN. Therefore, the ignition timing θ immediately after the complete explosion of the engine 10 (at time tl1 in FIG. When the idle speed N8 exceeds the idle speed NIDL and the engine speed N8 is greater than the target idle speed N1° (at t12 in Figure 1)
to tld), it is set to a value on the retard side.

When the ignition timing θ is set to the advanced side, the engine speed increases, and when it is set to the retarded side, the engine speed can be lowered. From time tlZ to tlA so as to increase the engine speed from time t12 to time t12.
It acts to reduce the engine speed between times.

This ignition timing control prevents the engine speed from rapidly increasing.

It is checked in subsequent steps 50 and 51 whether the ignition timing θ set in step 49 is within the upper and lower limit values (clip values) ranges set on the advance side and the retard side.

If the ignition timing θ is set to a value far outside the upper and lower limit value ranges, there is a risk that undesirable situations such as afterfire may occur. If it is larger (when the determination result in step 50 is negative), the process proceeds to step 52, where the ignition timing setting value θ is reset to the upper limit value on the advance side, and the ignition timing setting value θ is
is outside the retard side lower limit range and is smaller than this (
If the determination result in step 51 is negative), the process proceeds to step 53, where the ignition timing setting value θ is reset to the lower limit value on the retard side. If both of the determination results in steps 50 and 51 are affirmative and the ignition timing setting value θ is within the upper and lower limit value ranges, the set value is maintained at step 49 and the program is terminated.

The electronic control unit 20 outputs a drive signal to the igniter device 22 based on the ignition timing θ set by executing the program shown in FIG. 3, and generates a high voltage at a crank angle position corresponding to the set ignition timing θ. In this way, by executing the idle stabilization ignition timing control, the engine speed is quickly stabilized near the target idle speed NIDL after starting, and the idle operation can be stabilized.

In addition, in the above-mentioned embodiment, the ISC valve 18 immediately after starting
Although various modifications are conceivable for oven loop control of the valve opening of the ISC valve 18, any type of oven loop control that controls the ISC valve 18 at a predetermined valve opening for a predetermined period after startup is possible. It's okay.

Furthermore, the starting point of feedback control of the valve opening degree of the SC valve 18 is not limited to the time point shown in the embodiment (time tld in FIG. 1); Feedback control may be started when the valve opening degree is reached.

(Effects of the Invention) As detailed above, according to the ignition timing control method immediately after the start of an internal combustion engine of the present invention, the bypass passage bypasses the throttle valve until a predetermined period has elapsed from immediately after the start of the internal combustion engine. The feedback control of the bypass valve disposed in The engine speed rises and falls immediately after starting,
Hunting etc. can be prevented, and the engine speed can be quickly stabilized to the target idle speed, thereby stabilizing the idle operation.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a timing chart showing changes over time in the valve opening degree of the ISC valve (bypass valve), ignition timing, and engine speed for explaining the method of the present invention. FIG. 2 is a block diagram showing the overall configuration of an ignition timing control device that implements the method of the present invention, and FIG.
FIG. 2 is a flowchart showing the ignition timing control procedure for idle stabilization, which is executed by the electronic control unit 20 immediately after the engine starts, and FIG. 2 is a timing chart showing changes over time in the valve opening degree of a valve (bypass valve), ignition timing, and engine rotation speed. 10... Internal combustion engine, 12... Intake passage, 15.
...Throttle valve, 17...Bypass passage, 18...
・IsC valve (bypass valve), 20... Electronic control unit, 22... Igniter device, 24
...Distributor, 26...Spark plug, 30.
...Idle switch, 31...Crank angle sensor. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagato Figure 2 Figure 4 Time Figure 1

Claims (2)

[Claims] (1) A bypass passage that bypasses a throttle valve is connected to an intake passage of an internal combustion engine, and a bypass valve is disposed in the middle of the bypass passage, and when the internal combustion engine is in an idling operating state, a detected engine rotational speed value is In the ignition timing control method immediately after the start of an internal combustion engine, which feedback controls the valve opening of the bypass valve according to the target idle speed, the feedback control of the bypass valve is performed immediately after the start of the internal combustion engine until a predetermined period has elapsed. 1. A method for controlling ignition timing immediately after starting an internal combustion engine, characterized in that the ignition timing is controlled to a predetermined valve opening by prohibiting the engine speed, and the ignition timing is feedback-controlled according to a detected engine speed value and a target idle speed. (2) The ignition timing set by the feedback control is compared with at least one of a predetermined retard limit value and a predetermined advance limit value, and when the ignition timing set value exceeds at least one of the limit values, it is fixed to the limit value. An ignition timing control method immediately after starting an internal combustion engine according to claim 1, characterized in that: