JPS6053671A - Ignitor for internal-combustion engine - Google Patents

Abstract

PURPOSE:To adjust the replacing time for plugs by making same the polarity of the voltage distributed onto a spark plug, thus eliminating the difference in the consumption amount of plug electrodes. CONSTITUTION:When a cylinder discriminating signal Ns and an ignition signal A are input into an ignitor 3, a drive circuit 34 turns ON a transistor 32a, and a high voltage is generated in a secondary coil 4a, and a spark is generated in a plug 102. When the rotor of a distributor 20 rotates by 45 deg. and an ignition signal B is input into the drive circuit 34, the transistor 32a is turned ON, and a high voltage having a reverse polarity is generated in the secondary coil 4c. At this time, in an electric-current passage through high withstand-voltage diodes 5 and 6, each of the voltages spplied onto plugs 101 and 102 is a voltage having a positive polarity, and a difference is not generated in the exhaustion of the plugs. Therefore, the necessity of an expensive plug is obviated, and the replacing time for plugs can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition device for distributing voltage to a plug used in a multi-cylinder internal combustion engine.

[Prior art]

As shown in Figure 1, the ignition system of a conventional multi-cylinder internal combustion engine is
The control unit 40 sends an ignition signal to the coil with igniter 3 based on the intake air amount, battery voltage, and rotation signal.
There is a method in which a command is issued alternately to the power supply terminals a and 3b, and the power is distributed to the plugs of each cylinder at the distributor 2o, which waits for the double power distribution function. The disadvantage of using this method is that two coil-with igniters are required, which is not desirable due to problems such as installation space and cost. Also, Japanese Patent Application Publication No. 5
The systems disclosed in Japanese Patent Application Laid-Open No. 7-18456 and Japanese Patent Application Laid-Open No. 57-16260 are shown in FIG. This is crank angle sensor 1
Based on the detection signal No. 2, the control unit 40 controls the drive circuit 34 to alternately turn on and off the transistors 32a and 32b, thereby alternately energizing the primary coils 4a and 4b of the ignition coil 41, and the secondary coil 4c.
generates a voltage whose polarity changes alternately. When a positive polarity voltage is generated in the secondary coil 4c, the secondary coil 4c
c, diode 2a, side polarity 24, and plug 1
A positive spark current flows in the current path of 04, and then when the rotor rotates 45 degrees, a negative voltage is generated in the secondary coil 4c, and the secondary coil 4C, ground, plug 1o3, diode 2b, and secondary A negative spark current flows through a current path returning to the coil 4c. However, since this spark current has a different polarity, experimental results have shown that as the mileage increases, as shown in Figure 3, there is a difference in the wear of the plug electrodes, which causes a difference in the timing of replacing the plugs.

Conventionally, a platinum plug with a platinum alloy tip welded to the electrode has been used, which requires less wear and tear on the electrode over the distance traveled than a regular plug, but is more expensive.

[Purpose of the invention]

In order to solve the above-mentioned problems, the present invention eliminates the difference in the amount of wear of the plug electrodes depending on the mileage by making the polarity of the voltage distributed to the plugs the same. The purpose is to provide engine ignition systems.2. .

〔Example〕

The present invention will be described below with reference to an embodiment not shown in FIG.

1 is the battery, 20 is the two rotors 2C22d, and the corresponding sizes 1: electrodes 22.23°, 25.28 and 2
1, 24, 26, and 27 are equipped with a double power distribution mechanism. 3 is a drive circuit 34 and a transistor 32.
an igniter that turns on and off alternately a and 32b, 40
is the ignition timing and closing angle (ignition energization,
41 is an ignition coil having primary coils 4a, 4b and a secondary coil 4c;
5 and 6 are high voltage diodes whose cathodes are connected to both ends of the secondary coil 4c and whose anodes are grounded;
is a key switch, and 101 and 102 are plugs connected to side electrodes 21 and 22 of the distributor 20 to distribute power. However, although this embodiment is for an eight-cylinder internal combustion engine, only two plugs are shown and the others are omitted for the sake of simplicity.

Next, the operation of the above configuration will be explained. When the key switch 7 is in the closed state, the ignition signal A of the control unit 40, which is instructed from the cylinder discrimination signal Ns and ignition signal NP among the intake pipe pressure signal P, battery voltage signal 8, and crank angle signal, is sent to the igniter 3. When input, the drive circuit 34 turns on the transistor 32a. When a current controlled to a predetermined value by the drive circuit 34 is applied from the battery 1 to the secondary coil 4a, a high voltage is generated in the secondary coil 4c at the ignition timing Sa as shown in FIG. The current path of this high voltage spark current is from the secondary coil 4c, through the rotor 2C% side electrode 22, to spark at the plug 102 (FIG. 5 (C1)), and then to the secondary via the ground and high voltage diode 5. Returning to the coil 4C.Next, when the rotor of the distributor 20 has rotated 45 degrees, when the ignition signal B is input to the drive circuit 34, the transistor 32b is turned on and the primary coil 4b is turned on.
is energized, and a high voltage having a polarity opposite to that described above is generated in the secondary coil 4c. In this case, the current path includes the secondary coil 4c, the rotor 2d, the side electrode 21, the plug 101,
ground, and returns via the high voltage diode 6. Although the high voltage generated in the secondary coil 4C changes alternately in this way, the voltage applied to the plugs 101 and 102 in the current path via the high voltage diodes 5 and 6 is FC+ in FIG. As shown in FIG. 3, the voltage is positive, and there is no difference in plug wear as shown in FIG. 3 of the above-mentioned experimental results. Therefore, there is no need for 1f1i+a'[i platinum plugs, and the plugs can be replaced at the same time.

In the embodiment described above, the anodes of the high voltage diodes 5 and 6 were grounded, and the cathodes were connected to both ends of the secondary coil 4C, but the orientation of the high voltage diodes 5 and 6 was reversed, that is, the anodes were connected to both ends of the secondary coil 4C. It goes without saying that the same effect can be obtained by connecting the cathode to the ground at both ends of the secondary coil 4C to unify the spark current into a negative polarity current.

In addition, a high voltage diode 5.6 was published in Japanese Patent Application Laid-Open No. 56-16576.
If it has a breakdown voltage as shown in Publication No. 7,
This prevents leakage from the rotor to open side electrodes and ground, and also prevents deterioration of the distributor cap and grease due to flashover.

Further, as shown in FIG. 6, by inserting a high voltage diode 8.9, the potential difference between the rotors can be reduced. In other words, when a negative polarity current flows through the plug 102, the anode of the high voltage diode 5 is at almost zero potential, and a negative voltage of about -30 to -40 KV is applied to the side voltage 822. Without the high voltage diode 9, the rotor The potential difference between 2C and 2d is 30
~40 to about ■. Therefore, high voltage diode 8
By adding 9°, the potential difference between the rotors 2C and 2d can be reduced.

Further, as shown in FIG. 7, a DC-DC converter 11 for plasma ignition may be added to improve ignition performance. To explain its operation using the time chart of FIG. 8, the resistors 33a and 33b (
When the potential of Fig. 4) reaches the operating level (v+b), D(,
-Start the DC converter 11 and set it to the output (Fig. 8 (C)
) By repeatedly performing the operation of generating a voltage of minus several kilovolts and stopping at the spark timing S, sufficient energy can be supplied without the need for a special high-voltage diode or the like.

Also, the high voltage diodes 6.7 and 8.9 are connected to the ignition coil 41.
It may be built inside.

〔Effect of the invention〕

As described above, according to the present invention, the same poles are connected to both ends of the secondary coil of the ignition coil, and the polarity is set in the forward direction on the spark current path of the voltage generated in the secondary coil. By providing a diode, the polarity of the voltage distributed to the plugs is the same, which eliminates the difference in the wear amount of the plug electrodes used depending on the mileage, and has the excellent effect that all plugs can be replaced at the same time. There is.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 are block diagrams of a conventional ignition device, Fig. 3 is a consumption characteristic diagram of a plug electrode, Fig. 4 is a block diagram of an ignition device of the present invention, and Fig. 5 is an embodiment of the present invention. 6 and 7 are block diagrams showing another embodiment of the present invention, and FIG. 8 is a time chart showing the operation of another embodiment of the present invention. 2, c, 2d...rotor, 4a, 4h...-next
f no 1 no, 4C...Secondary coil, 5.6...High voltage diode, 20...Distributor, 21-2
B... side electrode, 101, 102... plaque. Representative Patent Attorney Ken Okabe Figure 3 114 (Manful Figure 5 Figure 4)

Claims (1)

[Claims] An ignition coil that generates a voltage whose polarity changes alternately in the secondary coil by controlling the energization of the primary coil, and an ignition coil that has terminals of the same polarity connected to both ends of the secondary coil, and a current path when the voltage is generated. An ignition device for an internal combustion engine, comprising: a diode installed at the top so that the polarity is in the forward direction.