JPS62139973A - Device for controlling ignition timing for internal combustion engine - Google Patents

Abstract

PURPOSE:To stabilize rotation at the time of idling with a low cost structure by generating an ignition signal when a certain period of time has elapsed after a predetermined crank angle position is reached, under a low engine speed area. CONSTITUTION:When engine speed is in a defined range under an idling condition in which the outputs of both accelerator switch 1 and an engine speed judging circuit 5 become high-level signals, an ignition signal from a pick-up coil 2 is fed to a reference crank angle detecting circuit 11 via a switchover circuit 4 by means of a switchover signal. Then, a trigger signal which is outputted when a crank angle has reached a defined angle position, is set out to an igniter 8 as an ignition signal after being delayed for a certain time through a delay circuit 12, to spark an ignition plug 10 through the operation of an ignition system. Thus, since the ignition timing is generated being delayed by a certain time from a defined crank angle position, the lead angle of ignition timing can be automatically controlled in accordance with engine speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition timing control system for an internal combustion engine that can maintain a stable rotational speed of 1:1 particularly in a low rotational speed range such as during idling.

(Prior Art) It is well known that the rotational speed of an internal combustion engine during idling is extremely unstable.

For example, when the internal combustion engine is cold, especially when starting the internal combustion engine in the winter or when the internal combustion engine is idling when it has not warmed up sufficiently after starting, combustion efficiency may be poor or the oil may be warm. Due to its high viscosity, the rotation speed tends to be low. In addition, in the summer or when idling after the internal combustion engine has warmed up, the rotation speed may be lower than l11. There is a tendency to increase.

In order to eliminate the instability of the rotational speed during idling, for example, the rotational speed can be detected using electric f-control and fuel and air can be supplied. There is one that adjusts d slightly to A so that the rotation speed becomes constant.

(Problem to be solved by the invention) As described above, since the rotational speed during idling is unstable, stabilization is being carried out, but conventional control does not require mechanical mechanisms and their mechanisms. 7t to operate
lt? -There was a problem that the control circuit became complicated and expensive.

This invention was made in view of the above points, and it is easy to understand the following points:
An object of the present invention is to provide an ignition timing control device for an internal combustion engine that stabilizes the rotational speed during idling with a simple configuration.

(Means for Solving the Problems) In order to solve the problems described above, the present invention includes a rotation speed determination circuit that determines whether the rotation speed of an internal combustion engine is in a predetermined low rotation speed region; 1) An ignition signal generation control circuit that generates an ignition signal after a certain period of time has elapsed after the crank angle of the internal combustion engine reaches a predetermined angular position when it is determined that the engine is in the low rotational speed region. It is characterized by having the following.

(Function) In this invention, the rotation speed determination circuit determines that the rotation speed is in a predetermined low rotation speed region, and the ignition signal generation control circuit generates an ignition signal after a predetermined time elapses from a predetermined crank angle. let As a result, when the rotational speed of the internal combustion engine becomes high, the ignition timing is retarded, and when the rotational speed of the internal combustion engine is low, the ignition timing is advanced, so that a substantially constant idle-link rotational speed can be maintained.

(Example) Next, an example of the present invention will be described with reference to the drawings.

First, we will explain the principle of this invention using the timing chart in Figure 1.
This will be explained with reference to -h.

Generally, ignition during idling is carried out by generating ignition I':x'JSs when the crank reaches a certain angle position from the crankshaft dead center TDC, as shown in Fig. .

The ignition timing is preferably about 30 degrees BTDC from the standpoint of thermal efficiency, but as the ignition timing is advanced, the concentration of hydrocarbon components in the exhaust gas increases, so there are certain limitations from the standpoint of exhaust gas purification. In particular, the idle link g4i"f is a problem in 2
In the case of a cycle internal combustion engine, it is preferable to retard the timing as much as possible.

The generation timing of the ignition signal Ss is set to a predetermined ignition timing in consideration of these points, but since this ignition timing is fixed, for example, when the internal combustion engine is cold, especially in the winter, The rotational speed decreases during startup or when the internal combustion engine is not yet sufficiently warmed up after it has started. Moreover, in summer or when the internal combustion engine is idling after it has warmed up, the rotational speed tends to increase.

In this embodiment, in order to keep the rotational speed of the internal combustion engine constant during idling, ignition No. 13 is generated after a certain period of time has elapsed from the time when a predetermined reference crank angle position is detected. That is, 1. For example, as shown in FIG. 1(B), when the crank angle position reaches 55 degrees BTDC from the F dead center TDC, a trigger signal St is generated, and this trigger signal St
The ignition signal S is activated after a certain period of 5m5ec has elapsed since the occurrence of
It is generating s. The crank rotation angle that rotates during the fixed time of 5 ms depends on the rotation speed, and the higher the rotation speed, the larger the crank rotation angle becomes, and the one ignition timing becomes retarded. Conversely, when the rotational speed becomes low, the ignition timing is set in an advanced direction, and the rotational speed becomes high and stabilized.

Fig. 1 (B) shows the generation timing of the ignition signal at a rotational speed of 11,000 rpm of the internal combustion engine.If the trigger signal St is generated at 55 degrees BTDC, and then the ignition signal Ss is generated after 5 m5ec has elapsed, the timing is 25 degrees. The ignition signal Ss comes to be generated at BTDC.

Similarly, Fig. 1 (C) shows the rotational speed of the internal combustion engine at 1500 rpm.
Showing an example of the timing of ignition A and No. 3 of m, 55 degrees BTD
A trigger signal St is generated at C, and its fQ 5 m
If the ignition signal Ss is generated after s e c has elapsed, the ignition signal Ss will eventually be generated at 10 degrees BTDC.

FIG. 2 is a block diagram showing an embodiment of the present invention. As described above, in this invention, since the rotational speed of the internal combustion engine is controlled in a low rotational speed state such as during idling, that state is first detected. Therefore, the accelerator switch 1 is set to low level No. 14 when the accelerator is depressed and under load, and to high level S when the accelerator is not depressed and under no load.
Output the number. In other words, the accelerator switch 1 produces an output when the throttle valve is closed.

The pickup coil 2 is provided close to the tooth width provided on the crankshaft of the internal combustion engine, and can obtain an output proportional to the rotational speed of the internal combustion engine. This output is manually input to the rotational speed calculation circuit 3 and the switching circuit 4, and the rotational speed calculation circuit 3 determines the rotational speed of the internal combustion engine based on the output from the pickup coil 2, and supplies it to the rotational speed determination circuit 5. The rotational speed determination circuit 5 determines whether or not the rotational speed of the internal combustion engine is in the low rotational speed region that is controlled by the present invention. For example, as shown in FIG. When the speed is 1500 rpm, the high level signal is output, and when the speed is below 11000 rpm or at 1500 rpm.
When the rotation speed is below rpm, a low level signal is output.

The output of the rotational speed determination circuit 5 is manually input to a determination circuit 7 that constitutes a part of the ignition signal generation control circuit 6. This determination circuit 7 is composed of an AND circuit 70, and the AND circuit 70 supplies a switching signal to the switching circuit 4 when both the output of the accelerator switch 1 and the output of the rotational speed determination circuit 5 are high level signals. By inputting the switching signal, the switching circuit 4
and the output of the pull-up coil 2 can be switched. In other words, the accelerator switch 1 may not be in the idling state, or the rotational speed of the internal combustion engine may be lower than 1000.
When the rpm is other than 1500 rpm, the ignition from the pickup coil 2 (No. ii is manually powered by the igniter 8) via the switching circuit 4.

This igniter 8 energizes the primary side of the ignition coil 9 at the set ignition timing and time to induce a high voltage on the secondary side of the ignition coil 9, and the ignition plug lO provided in the internal combustion engine
It is designed to spark.

On the other hand, when the outputs of the accelerator switch 1 and the rotational speed determination circuit 5 are both high-level signals, that is, when the rotational speed is 1000 rpm to 1500 rpm in an idling state, the switching signal connects to the switching circuit 4. Then, the ignition signal from the pickup coil 2 is supplied to the reference crank angle detection circuit 11 via the switching circuit 4.

The reference crank angle detection circuit 11 is for determining the timing at which trigger No. 13 St in FIG. 1 is generated.
For example, the trigger signal St is output when the crank angle reaches the angular position of 55 degrees from top dead center. This trigger signal St is delayed by a predetermined time (here, 5 m5ec is set as shown in FIG. 1) in the delay circuit 12, and then sent to the igniter 8 as an ignition signal Ss, and the ignition system operates in the same way as described above. This causes the spark plug 10 of the internal combustion engine to spark.

As mentioned above, in this embodiment, when the rotation speed is within a predetermined low rotation speed region, the ignition timing is delayed by a certain period of time from the predetermined crank angle position, so that the ignition timing is advanced in accordance with one rotation speed. It is automatically controlled, and as a result, a constant rotational speed can be maintained.

In addition, in the embodiment described in ntt, the ignition timing is controlled based on both the operating state of the accelerator switch 1 and the determination result of the rotational speed of the internal combustion engine, or the rotational speed is stabilized in a low rotational speed state. Therefore, depending on the internal combustion engine, the ignition timing may of course be controlled when the rotational speed is in a low rotational speed region set as f.

Further, in the embodiment described in t1η, the input parameters of the determination circuit 7 were the outputs of the accelerator switch l and the rotational speed determination circuit 5, but a choke operation state output may be added to these.

In this case, the determination circuit 7 has a configuration in which an OR circuit 71 is added, as shown in FIG. That is, the operation state output and the output of the rotational speed determination circuit 5 are connected to the OR circuit 71.
The output of the OR circuit 71 and the accelerator switch 1 are
The output of the AND circuit 70 becomes the output of the AND circuit 70, and the output of the AND circuit 70 is switched to the VJ switching circuit 4 in FIG. Supplied as an I signal. Other operations are the same as those in FIG.

(Effects of the Invention) As described above, in the present invention, when it is determined that the rotational speed of the internal combustion engine is in a predetermined low rotational speed region,
Since the ignition signal is generated after a certain period of time has elapsed after the crank angle of the internal combustion engine reaches a predetermined angular position f, the crank angle at which the ignition signal is generated is determined automatically according to the rotational speed of the internal combustion engine. Changes to Therefore, by simply adding a simple circuit, it is possible to automatically advance or retard the angle depending on the rotational speed of the internal combustion engine, and it is possible to stabilize the rotation during idling with an inexpensive configuration.

[Brief explanation of drawings]

Figures 1 (A) to (C) are timing charts for explaining the operating principle of this invention, Figure 2 is a basic configuration block diagram of an embodiment of this invention, and Figure 3 is the rotation speed in Figure 2. Fig. 4 is a block diagram showing another embodiment of the judgment circuit in Fig. 2; ! ...Accelerator switch 2...Pickup coil 3...Rotation speed judgment circuit 4...Switching circuit 5...Rotation speed judgment circuit 6...Ignition signal generation control circuit 7...Judgment circuit 8. ... Igniter 9 ... Ignition coil 10 ... Spark plug 11 ... Base, crank angle detection circuit 12 ... Reciprocal circuit

Claims (1)

[Claims] A rotation speed determination circuit that determines that the rotation speed of the internal combustion engine is in a predetermined low rotation speed region, and a crank angle of the internal combustion engine that determines that the rotation speed of the internal combustion engine is in the predetermined low rotation speed region. An ignition timing control device for an internal combustion engine, comprising an ignition signal generation control circuit that generates an ignition signal after a predetermined period of time has elapsed after reaching an angular position.