JPS59201971A - Method of controlling ignition timing for internal-combustion engine - Google Patents

Abstract

PURPOSE:To promptly eliminate variations in the rotational speed of an engine, by providing such an arrangement that, when the absolute value of variations in the engine rotational speed is above a predetermined value and as well the engine load is constant or decreases, the ignition timing is retarded or advanced in accordance with the negative or positive direction of the variations in the engine rotational speed. CONSTITUTION:Upon engine operation, a control circuit 30 performs the subtraction between the present value and the previous value in accordance with the output of a rotational speed sensor 28 to compute variations in the rotational speed of the engine, and judges whether the averaged value of the variations is above a predetermined value or not. If it is YES, the control circuit 30 then judges whether the pressure of an intake-air pipe detected by an intake-air pipe pressure sensor 10, or the load, is below a predetermined value or not, and, if it is YES, further judges whether a variation in the load is less than a predetermined value or not. If it is judged to be YES, the ignition timing is retarded when the averaged value of variations in the engine rotational speed is positive. However, when it is negative, an ignitor 32 is controlled to advance the ignition timing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control method for an internal combustion engine, and more particularly to a method for controlling ignition timing in accordance with a change in engine speed.

Conventionally, in fuel-injected internal combustion engines that control ignition timing using a microcomputer, the fuel injection is cut off when the throttle valve is fully closed and the engine speed is above a predetermined value. When the pedal was depressed and then returned to its original position (tip-in), the engine speed could fluctuate violently using this tip-in as a trigger. On the other hand, a method for controlling ignition timing according to fluctuations in engine speed is to prevent engine speed undershoot after racing when the amount of change in engine speed exceeds a predetermined value and when the throttle valve is fully There is a method of controlling the ignition timing to the advanced side according to the amount of change in engine speed when the engine is in the closed state. However, since this method only controls the ignition timing to the advanced side, it has little effect on the above-mentioned fluctuations during tip-in, and since the ignition timing is controlled only when the throttle valve is fully closed, it is difficult to suppress fluctuations. The problem was that it couldn't be done.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ignition timing control method for an internal combustion engine that cancels undesirable fluctuations in engine speed.

In order to achieve the above object, the configuration of the present invention is such that when the absolute value of the amount of change in the engine speed is equal to or greater than a predetermined value and the engine load is constant or decreasing, if the amount of change in the engine speed is positive, this change will occur. The angular ignition timing is retarded in proportion to the amount of change, and if the amount of change in engine speed is negative, the angular ignition timing is advanced in proportion to this amount of change. As a result, when the engine speed changes to increase, the ignition timing is retarded, and when the engine speed changes to fall, the ignition timing is advanced.

An example of an internal combustion engine to which the present invention is applied will be explained in detail with reference to FIG. Air cleaner (not shown)
An intake temperature sensor 2 is installed downstream of the intake air temperature sensor 2 for detecting the temperature of intake air and outputting an intake temperature signal. A throttle valve 4 is arranged downstream of the intake temperature sensor 2. A surge tank 8 is provided downstream of the throttle valve 4, and a pressure sensor 10 is installed in the surge tank 8 to detect the intake pipe pressure downstream of the throttle valve and output an intake pipe pressure signal.
is installed. The surge tank 8 is communicated with a combustion chamber 14 of the engine via an intake manifold 12. A fuel injection valve 16 is attached to the intake manifold 12 for each cylinder. The combustion chamber 14 of the engine is communicated via an exhaust manifold with a catalytic converter (not shown) filled with a three-way catalyst. Further, a water temperature sensor 20 is attached to the engine block to detect the engine cooling water temperature and output a water temperature signal. A tip of a spark plug 22 projects into the combustion chamber 14 of the engine, and the spark plug 22 is connected to a distributor 24+. distributor 2
4 includes a cylinder discrimination sensor 26 each consisting of a pickup fixed to the distributor housing and a signal rotor fixed to the distributor shaft.
and an engine rotation speed sensor 28 are provided. The cylinder discrimination sensor 26 sends a cylinder discrimination signal every 720° CA to a control circuit 30 composed of a microcomputer or the like.
For example, the engine rotation speed sensor 28 is output to 300C.
The control circuit 3Q- outputs an engine rotational speed signal for each A. Further, the distributor 24 is connected to the igniter 32.

As shown in FIG. 2, the control circuit 30 includes a central processing unit (C
PU) 36, read-only memory (ROM) 38, random access memory (RAM) 40, backup RAM (BU-RAM) 42, input/output port (■10) 4
4. An analog/digital converter (ADC) 46 and buses such as a data bus and a control bus connecting these are configured. A cylinder discrimination signal and an engine rotation speed signal are input to l1044, and
A fuel injection signal that controls the opening/closing time of the fuel injection valve 16 and an ignition signal that controls the on/off time of the igniter 32 are outputted via the drive circuit. In addition, in ADC46,
An intake pipe pressure signal, an intake air temperature signal, and a water temperature signal are input and converted into digital signals. The ROM 38 stores in advance a map of the basic ignition advance angle θBASF determined by the engine speed and the intake pipe pressure, an open side 1 program, and the like.

Next, a processing routine when the present invention is implemented using the engine as described above will be explained with reference to FIG.

This routine is an interrupt routine that is executed every predetermined time (for example, 32 m5ec).

In step 51, the latest engine speed NE calculated from the engine speed signal and stored in the RAM
i is taken in, and in step 52, the engine rotation speed N
The previous engine speed NEi-1 is subtracted from Ei to calculate the amount of change ΔNEi in the engine speed. This amount of change ΔN E 1 in the engine speed has a relatively large deviation, so in step 53, the change amount ΔN in the previous engine speed and the current change in engine speed ΔN
The average value ΔNE of the change meter of the engine speed is determined by taking the average with El. In the next step 54, the absolute value l,v N E+ of the average value of the amount of change is set to a predetermined value (for example, 37,
5 r, p, m 732 m 3ec ) or more. When the absolute value II M E+ of the average value of the amount of change is greater than a predetermined value, that is, when the amount of change in the engine speed is large, in step 55, the current engine speed N E i changes to the engine speed. It is determined whether the value is within a predetermined range (for example, 700≦NEi≦2500), and if the engine speed N b h is within a predetermined range, the intake pipe pressure signal is changed in step 56. Based on this, it is determined whether the intake/α pressure PM is below a predetermined value (for example, 400 mrrLHg), that is, whether the load is low.

If the intake pipe pressure PM is less than or equal to the predetermined value, the amount of change ΔPM in the intake pipe pressure is set to a predetermined value (for example, 2
0 mmHg/24 m 5ec)
F1] Cut. The amount of change ΔPM in this intake pipe pressure is 19"
When it is less than a fixed value, that is, when the load is constant (ΔPM=0) and the load is decreasing, the retard amount θT is calculated in step 58 based on the following equation.

Note that when the load decreases, the intake pipe pressure may resonate and the value of ΔPM may become positive, so the predetermined value in step 57 is set to an extremely small positive value.

θT←−α・ΔN E・・・・・・・・・・・・・・・
...(1) However, α is a positive constant.

As a result, when the average value ring of the amount of change in engine speed is positive, that is, when the engine speed changes to increase, the retard amount 19T becomes negative, and when the average value JNE of the amount of change is negative. That is, when the engine speed changes to decrease, the 1[) angle j14: 0' T becomes positive.

On the other hand, when the absolute value 1 nl is the predetermined value, when the engine speed NEi is outside the predetermined value, and when the intake pipe pressure exceeds the predetermined value, the amount of change ΔPM in the intake accessory force is When it is equal to or greater than the predetermined value, in step 59, the retard amount θ
Let the value of T be 0.

After determining the retardation amount OT/ζ as described above, the ignition shearing angle θ is determined in the ignition advance angle calculation routine shown in FIG. That is, in step 61, the ignition advance angle O is determined by adding the Y angle amount θT to the basic ignition advance angle 61 BASE determined by the two-dimensional method from the map stored in the ROM. In the next step 62, the ignition advance angle O is corrected based on the intake temperature, cooling water temperature, etc., to determine the effective ignition advance angle.

Then, in the next ignition timing side @l routine (not shown), the igniter is turned off so that it is ignited at the actual ignition advance angle.

As a result of the above, under low load, steady operating conditions, and deceleration, if the engine speed changes to rise, the ignition timing will be delayed, and if the engine speed changes to fall, the ignition timing will change. The engine rotational speed is controlled to move forward, and fluctuations in engine speed 75 are prevented.

FIG. 5 shows a comparison between the conventional ignition timing Il control and the ignition timing control of this embodiment when the accelerator pedal is depressed for a very short time from the fuel injection cut state.

In the case of this embodiment shown in FIG. 5(B), the ignition timing is retarded and advanced by the retard amount θT, so that fluctuations in engine speed converge more quickly than in the conventional example shown in FIG. 5 (■). It has become.

Although the above description has been made regarding an engine in which the basic ignition advance angle is determined based on intake pipe pressure and engine speed, the present invention determines the basic ignition advance angle based on the intake air per engine revolution. It can also be applied to engines.

As explained above, according to the present invention, it is possible to promptly prevent fluctuations in the engine speed 75E, and also to prevent undershoot of the engine speed after racing or when transitioning from a deceleration state to an idling state. You can get the effect that you can do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an engine to which the present invention is applied, FIG. 2 is a block diagram showing the control circuit of FIG. 1, and FIG.
Figure 4 is a flowchart showing the retard amount calculation routine, Figure 4 is a flowchart showing the ignition advance calculation routine, and Figure 5 (B) compares the characteristics of conventional ignition timing control and the ignition timing control of the present invention. FIG. 10... Pressure sensor, 16... Fuel injection valve. 28°°°゛engine rotation speed sensor. 32...Igniter, 30...Control circuit. Agent Tatsuyuki Unuma (and 1 other person) Figure 3 Figure 4 Figure 51 (A) (B)

Claims (1)

[Claims] (1) When controlling the ignition timing according to the amount of change in engine speed, when the absolute value of the amount of change in engine speed is more than a predetermined value and the engine load is less than a predetermined value, and the engine load is constant or decreasing, If the amount of change in the engine speed is positive, the angle ignition timing is retarded in proportion to the amount of change, and if the amount of change in the engine speed is negative, the angle ignition timing is retarded in proportion to the amount of change. A method for controlling ignition timing for an internal combustion engine, characterized by advancing the ignition timing.