JPS61116074A - Igniting device for 2-cycle engine - Google Patents

Abstract

PURPOSE:To prevent the irregular rotation of a 2-cycle engine by providing the engine with means intermittently igniting same at the idling rotation time whereby the scavenging in a cylinder thereof is bettered. CONSTITUTION:With the ON-OFF operation of a switching element within an ignition circuit synchronized with the rotation of a 2-cycle engine the primary current flowing in the primary coil 3 of an ignition coil 2 is abruptly intercepted, while at the secondary coil 4 side high voltage is obtained. In the above, an igniting device is provided with a monostable multiplexer 8 which is adapted to receive a signal a which turned over the primary current. From the monostable multiplexer 8, a pulse signal b whose pulse width being larger than that of the input signal a is generated and divided into 1/2 at a FF circuit 9 to form a division pulse signal c. Then it is supplied to an ignition circuit 5 via a drive circuit 10 to generate sparks intermittently in an ignition plug 1. While in the area beyond the idling rotation range, the drive circuit 10 is intercepted by the action of an circuit 11 intermittently stopping the ignition whereby the intermittent ignition is interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an ignition device for a two-stroke engine.

<Prior art> There are various types of ignition devices for two-stroke engines, including transistor types, but conventional ignition devices generate a spark from the spark plug once every revolution of the engine to ignite the engine. Normal.

<Problems to be Solved by the Invention> However, conventionally, two-stroke engines have had the disadvantage that rotational irregularities during idling are much larger than four-stroke engines. In other words, in a 2-stroke engine, when igniting by generating a spark every time as before, it is difficult to completely scavenge the air in the cylinder during idling, and the fresh air (mixture of unburned air and gasoline) in the cylinder is completely exhausted. The amount is around 5 to 10% of the total amount, and most of it is already burned gas. Therefore, even if a spark is emitted by a spark plug, the probability of ignition is low; it may or may not ignite, and after a mis-ignition, two doses of fresh air will accumulate in the cylinder, resulting in a strong explosion. This caused large rotation spots.

Means for Solving the Problems> In view of the problems of the prior art, the present invention aims to improve scavenging air in the cylinder during idling rotation and prevent uneven rotation. As a specific means for this purpose, a means for intermittently igniting the engine during idling rotation is provided.

<Function> If ignition occurs intermittently during idling, the scavenging air will improve by the amount of ignition that is thinned out, and fresh air between the cylinders will increase, increasing the probability of ignition (and preventing uneven rotation.

<Example> Hereinafter, the present invention will be described in detail with regard to the illustrated example.
In the figure, 1 is a spark plug, 2 is an ignition coil, and has a primary coil 3 and a secondary coil 4. 5 is the ignition circuit,
For example, it has a switching element such as a transistor that turns on and off in synchronization with engine rotation, and is designed to suddenly cut off the primary current flowing to the primary coil 3 side of the ignition coil 2 and generate a high voltage in the secondary coil 4. It is composed of Reference numeral 6 denotes a constant voltage circuit that rectifies and stabilizes the AC voltage generated in the primary coil 3, and has terminals 7 for applying Vcc voltage to various parts. 8 is a monostable multi-by-break, primary coil 3
An input signal (FIG. 2(a)) which is an inversion of the primary current flowing through the circuit is input, and the waveform is shaped into a pulse signal having a larger pulse width (FIG. 2(b)). 9 is a flip-flop circuit, which divides the pulse signal (bl) from the monostable multivibrator 8 into 1/2 to generate a frequency-divided pulse signal [second
(C)], and the ignition circuit 5 is operated intermittently via the drive circuit 10. 11
is an intermittent ignition stop circuit for shutting off the drive circuit 10 and operating the ignition circuit 5 every revolution when the engine rotates above idling (2000 to 4000 rpm), and is composed of, for example, a frequency/voltage conversion circuit. , FIG. 2 (d+) is equipped with a charging/discharging circuit that charges the capacitor when the frequency-divided pulse signal (C) from the flip-flop circuit 9 is on and discharges it when it is off, and the voltage across the capacitor is the reference value Vs. F-V turns on when
It is configured to generate a signal [FIG. 2(e)], and when the engine speed exceeds 400 rpm, the off time becomes shorter as shown by the dotted line, and the drive circuit 10 is cut off. In addition, when the engine speed is 200 Orpm or less,
Since the voltage generated by the primary coil 3 is small, the Vcc voltage applied from the terminal 7 of the constant voltage circuit 6 is insufficient and the drive circuit 10 does not work, so that the divided pulse signal tc+ is not supplied to the ignition circuit 5. It has become.

In the above configuration, the ignition circuit 5 is originally an on/off operation of a switching element synchronized with the engine rotation, and suddenly cuts off the primary current flowing through the primary coil 3 of the ignition coil 2, causing a high current to flow to the secondary coil 4 side. It operates to generate voltage.

On the other hand, the input signal (al) which is an inversion of the primary current flowing through the primary coil 3 acts as a monostable multi-by-break, 8, to generate a pulse signal (b) having a larger pulse width than the input signal (a). The frequency of this pulse signal fb) is divided into 1/2 by a flip-flop circuit 9 to generate a frequency-divided pulse signal (C1), which is then passed through a drive circuit 10 to an ignition circuit 5.
supply to. Therefore, if the engine speed is, for example, 2000
During idling rotation between rpm and 400 Orpm, the ignition circuit 5 operates when the pulse signal [C] is in the rising state and performs the original ignition operation, so sparks are generated intermittently in the ignition plug 1, causing intermittent ignites. In other words, when the engine speed is 3000 rpm,
Normally, 3000 explosion sounds are generated, but as shown in Figure 3 (^)
Because a high voltage is intermittently generated in the secondary coil 4 of the ignition coil 2 and the secondary coil 4 of the ignition coil 2 is intermittently ignited, the number of explosions is 1500 times, making it sound as if the engine is rotating at 1500 rpm. Then, by thinning out the ignition, the scavenging air becomes better and fresh air increases, and when the ignition becomes reliable, the explosion becomes more stable.

When the engine speed reaches 400 rpm or more, which is above the idling speed range, the intermittent ignition stop circuit 11 operates and cuts off the drive circuit 10. In other words, if the throttle is operated to increase the rotation speed, the frequency will increase accordingly, so the charging/discharging cycle of the charging/discharging circuit of the intermittent ignition stop circuit 11 will be short (so that the voltage across the capacitor will be equal to or lower than the reference value V).
s or more, the on time becomes much longer than the off time, and by shortening this off time, the drive circuit 10
cut off.

Therefore, the ignition circuit 5 returns to its original operation, as shown in FIG. 3(B).
As shown in the figure, high voltage is generated by the ignition coil 2 once every rotation, and the ignition returns to ignition each time.

When the engine rotation decreases from the idling rotation range to a low speed, the potential of the terminal 7 that applies the Vcc voltage to each part from the constant voltage circuit 6 decreases, the drive circuit 10 does not operate, and the ignition circuit 5 performs the ignition operation every time.

Therefore, there is no problem with starting performance at the time of starting, and even if the engine speed drops from idling for some reason, ignition starts every time, so unexpected engine stops can be prevented.

In the embodiment, a frequency/voltage conversion circuit is illustrated as the intermittent ignition stop circuit 11, but this essentially distinguishes between the idling rotation range and the other rotation range, and turns off the intermittent ignition when the rotation range is in the latter rotation range. Any configuration is acceptable as long as it can be stopped.

In addition, in the example, the idling rotation is 2000 to 4.
Although 00 rpm and 2 as the ignition thinning amount are illustrated, the rotation speed and the ignition thinning amount are arbitrary and change depending on the engine and its use.

Furthermore, the present invention is not limited to those having the transistor type ignition circuit 5, and can be implemented in CDI ignition devices and other devices. The configuration is not limited to the multi-by-break 8, the flip-flop circuit 9, the drive circuit 10, and the intermittent ignition stop circuit 11, but can be modified as appropriate depending on the type of ignition device.

<Effects of the Invention> According to the present invention, since the engine is ignited intermittently during idling, the scavenging performance during idling is improved, and stable rotation without irregular rotation can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart of each part thereof, and FIG. 3 is an operation waveform diagram. 1-・Spark plug, 2--Ignition coil, 5--Ignition circuit, 8
- Monostable multi-bi break, 9- Flip-flop circuit, 10- Drive circuit, 11- Intermittent ignition stop means.

Claims (1)

[Claims] 2, characterized in that the one- and two-stroke engine is equipped with a means for intermittently igniting the engine during idling.
Cycle engine ignition system.