JPS61182469A - Ingnition device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable a capacity discharge current to be controlled in accordance with a warmed condition of an engine, by electrically connecting a means, which forms an electrostatic capacity, in parallel to the spark gap of a spark plug while connecting in series to said means a resistance forming means which increases a resistance value if temperature rises. CONSTITUTION:If high voltage of an ignition coil 4 in an ingnition power supply 1 is fed to a spark plug 11 through a distributor 9, a discharge current is al lowed to flow in the spark plug 11. Here a device, generating a vibration of the discharge current between a spark gap 11d, of the spark plug 11 and an electrostatic capacity forming means 12 electrically connected in parallel to the gap 11d, increases the capacity discharge current. In this case, a resistance forming means 13, being connected in series to the electrostatic capacity forming means 12, limits the capacity discharge current. That is, the resistance forming means 13, having a positive temperature characteristic, is in a small value when an engine is in a cold state. Accordingly, the device, allowing the large capacity discharge current to flow in the spark plug 11 when the engine is in warming operation and/or cold starting operation, improves ignitionability of a mixture.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an ignition device for an internal combustion engine, and more particularly, a capacitor is connected in parallel with the spark gap of a spark plug to increase capacitance discharge energy during spark discharge. It relates to an ignition device that

(Prior Art) It is generally known that when a capacitor is electrically connected in parallel with the spark gap of a spark plug, the capacitive discharge energy during spark discharge increases. For example, the one published in Japanese Unexamined Patent Publication No. 123732/1983 is known.

This conventional ignition device has a multiple spark power source connected to a parallel-connected spark plug and capacitance forming means (for example, a capacitor) via an impedance element. Generate electrical discharge.

Therefore, a resonance phenomenon occurs between the capacitance and the impedance element, and the capacitive discharge current for ignition supplied to the spark plug increases, improving ignition performance. The carbon deposited on the spark plug is effectively removed.

(Problem to be Solved by the Invention) However, in such conventional ignition devices for internal combustion engines, the capacitive discharge current is always greatly increased due to the capacitance, and therefore, each ignition spark There is a problem in that increased capacitive discharge energy is applied to the spark gap of the spark plug, resulting in a very short life span of the electrodes of the spark plug.

In other words, an increase in capacitive discharge current improves startability and idling performance when the engine is cold, but after warm-up,
Particularly at high rotation speeds, when increased capacitive discharge energy is applied, the electrodes of the ignition flag become abnormally hot, causing severe wear and tear on the electrodes, resulting in a significantly shortened lifespan.

(Objective of the Invention) Therefore, the present invention improves engine startability, idling performance, etc. by adjusting the size of capacitance and adjusting the rate of increase in discharge current in accordance with the warm-up state of the engine. The purpose is to prevent abnormal deterioration of the electrodes and extend the life of the spark plug.

(Means for Solving the Problems) The ignition device for an internal combustion engine of the present invention includes a spark plug provided for each cylinder of the internal combustion engine, and a capacitance connected electrically in parallel with the spark gap of each spark plug. a capacitance forming means for forming;
In the ignition system for an internal combustion engine, a resistance forming means whose resistance value increases as the temperature rises is connected in series to the capacitance forming means, thereby supplying the spark plug to the spark plug according to the warm-up state of the engine. This adjusts the rate of increase in the number of discharge electrodes.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 to 3 are diagrams showing one embodiment of the present invention.

First, to explain the configuration, in FIG. 1, 1 is an ignition power source, and the ignition power source 1 includes a battery 2, an ignition switch 3, an ignition coil 4, a transistor 5, an ignition timing control circuit 6, and an ignition signal generator 7. We are prepared. The ignition signal generator 7 is composed of a magnetic pickup or the like, and outputs an ignition signal to the ignition timing control circuit 6 in synchronization with the crank angle of the engine. The ignition timing control circuit 6 outputs an ignition timing signal to the base terminal of the transistor 5 based on the ignition signal, and turns the transistor 5 on and off. When the ignition switch 3 is turned on, the transistor 5 turns ON and OFF.
By turning FF, the primary current flowing through the primary winding 4a of the ignition coil 4 is switched on and off, and a high voltage is induced in the secondary winding 4b.

The secondary winding 4b of the ignition coil 4 is connected to a power distributor 9 by a center cable 8, and the power distributor 9 connects the spark plug 1 provided for each cylinder by a high tension cable 10.
Connected to 1. High voltage terminal 11 of spark plug 11
In a, a capacitance forming means 12 and a resistance forming means 13 are electrically connected in parallel with the spark gap 11d formed between the center electrode 11b and the side electrodes 11c, and are connected in series with each other. is connected.

As the capacitance forming means 12, a normal ceramic capacitor may be used, or a shield camp of the spark plug 11 may be used. The resistance forming means 13 is, for example, a resistance mainly made of barium titanate, etc.
As shown in the figure, it is a resistor with positive temperature characteristics whose resistance value increases exponentially as the temperature rises.

Next, the action will be explained.

At the ignition timing, when the high voltage of the ignition coil 4 is supplied from the ignition power source 1 to the ignition plug 11 via the power distributor 9, a discharge current flows through the ignition plug 11. At this time, spark plug 1
Oscillation of the discharge current occurs due to a kind of oscillation phenomenon between the spark gap lid of No. 1 and the capacitance forming means 12 electrically connected in parallel, and the capacitance discharge current of the discharge current shown in FIG. To increase. This capacitive discharge current is influenced by the resistance value of the resistance forming means 13 connected in series with the capacitance forming means 12, and the resistance forming means 13 acts to limit the capacitive discharging current. And the resistance forming means 13 is
As shown in Figure 2, it has a positive temperature characteristic, and when the engine is cold, the value is small (10Ω or less), and at about 80℃ when the engine has been warmed up, it is 1. becomes Ω or more. Therefore, when the engine is warmed up or started when the engine is cold, a large capacity discharge current flows to the spark plug 11, and the ignitability of the air-fuel mixture is greatly improved. As a result, the startability and idling performance of the engine are improved, and the spark plug 11 can be prevented from becoming contaminated. Furthermore, as the engine warms up, the temperature near the resistance forming means 13 also rises, and the resistance value of the resistance forming means 13 increases in accordance with the warm-up state, thereby limiting the capacitive discharge current. (According to experiments, this discharge current is limited when the resistance value of the resistance forming means 13 is approximately 1Ω.
Therefore, it is preferable to limit the maximum value of the capacitive discharge current to approximately IOA. ) Therefore, the capacitive discharge current can be adjusted according to the warm-up state of the engine, and while maintaining good operating performance of the engine, abnormal deterioration of the electrode 11b of the spark plug 11 and IIC due to large discharge current can be prevented. can do. As a result, the life of the spark plug 11 can be extended.

(Effects of the Invention) According to the present invention, a large discharge current can be supplied when the engine is cold, and the discharge current can be adjusted in response to the warm-up state of the engine, thereby improving engine startability and idling performance. In addition, abnormal deterioration of the electrodes of the spark plug can be prevented and the life of the spark plug can be extended.

[Brief explanation of the drawing]

1 to 3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is an overall configuration diagram thereof, FIG. 2 is a temperature dependence characteristic diagram of the resistance value of the resistance forming means, and FIG. 3 is a diagram showing an example of the present invention. is a waveform diagram of the discharge current supplied to the spark plug. 11-m one spark plug, 11 d--- one spark gap, 12-1111 capacitance forming means, 13-1111 resistance forming means.

Claims (1)

[Claims] An ignition device for an internal combustion engine, comprising: a spark plug provided for each cylinder of the internal combustion engine; and a capacitance forming means that forms a capacitance electrically in parallel with the spark gap of each spark plug. An ignition device for an internal combustion engine, characterized in that a resistance forming means whose resistance value increases as the temperature increases is connected in series to the capacitance forming means.