JPS6248966A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable the safe operation of an engine by checking a secondary high voltage which is generated when an ignition coil is turned on, by means of a high voltage diode provided in an integrated form with the inside of said ignition coil. CONSTITUTION:In regular ignition timing, since a secondary side is connected so that a high voltage with negative polarity is generated on the bottom side terminal of both the terminals of a secondary coil 4b, a voltage applied to a high tension diode is in the forward direction. Thereby, when a power transistor 23 is off, the circuit for an ignition plug 8 is broken causing the plug 8 to be ignited. Although a secondary high voltage is generated when the power transistor 23 is on, however, a voltage with an opposite polarity to one in the case of regular ignition timing is generated on the secondary coil 4b, generating a high voltage with positive polarity on the bottom side terminal. Accordingly, an opposite voltage is applied to the high tension diode 7, and a secondary high voltage applied to the ignition plug 8 is checked, without causing the circuit of the ignition plug 8 to be broken when the transistor 23 is turned on. Thereby, an engine can be safety operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an internal combustion engine ignition system, and in particular, when the ignition coil is turned on (hereinafter referred to as ON), the secondary side generated on the secondary side of the ignition coil is This system is designed to prevent abnormal phenomena (failures) caused by high voltage internal combustion engines.

[Conventional technology]

In a conventionally well-known configuration, the secondary high voltage terminal on the secondary side of the ignition coil is connected to each spark plug via the rotor of the distributor and the electrode of the cap in the case of a distribution mechanism using a distributor. In those with simultaneous ignition coils, the two secondary high voltage terminals are directly connected to the spark plugs of each cylinder, and the ignition coils are turned on and off in synchronization with the rotation of the internal combustion engine. (hereinafter referred to as OFF), a secondary high voltage is supplied to each spark plug at the appropriate ignition timing.

In addition, the ON/OFF of the primary side of the ignition coil is usually a mechanical contact (point) built into the distributor.
Alternatively, a semiconductor such as a power transistor is used as the switching element of the ignition coil by waveform shaping the signal of the ignition signal source. Even with points or semiconductors, the opening and closing speed when turning on is not controlled, and the ignition coil is turned on at a speed determined by the switching speed of the capacitor or semiconductor inserted in parallel with the point. Ru.

[Problem that the invention seeks to solve]

However, in the conventional device described above, a voltage approximately equal to the power supply voltage minus the drop caused by the element is applied to both ends of the primary side of the ignition coil at the same time as the switching element is turned on, and the ignition coil is applied to the primary side of the ignition coil. The primary current determined by the ignition coil, external resistance, etc. that make up the circuit begins to flow.

Generally speaking, attention is focused only on the case where the switching element opens when determining the ignition timing and turns off the secondary current circuit to generate a secondary high voltage, but when the ignition coil is turned on, Naturally, a transient phenomenon occurs, and as a result, a secondary high voltage is generated on the secondary side of the ignition coil. The secondary high voltage generated when this ignition coil is turned on is turned off.
The polarity is opposite to that of the secondary high voltage that occurs at the normal ignition timing when the ignition occurs, and the oscillation frequency of the output voltage waveform is almost the same. This waveform is shown in FIG. In Figure 1, a, C
is the secondary waveform at the ignition timing, a is the waveform when the secondary side is open, C is the waveform at the time of break,
b is the waveform when the ignition coil is turned on. Although the value of the secondary high voltage (VZ in FIG. 1) at point b is about one-tenth of the output voltage level at the normal ignition timing, when the power source is 14V, the ignition coil generates about 2 to 4KV. FIG. 2 shows the power supply voltage characteristics of the secondary high voltage when this ignition coil is turned on. This voltage increases almost in proportion to the power supply voltage, and the output levels differ as shown by a, b, and c depending on the various ignition coils.

As mentioned above, even when the ignition coil is turned on, a secondary high voltage is generated on the secondary side of the ignition coil, but this secondary high voltage is normally passed through the rotary power distribution device of the distributor.
Furthermore, in those that do not use a distributor, the spark plug is connected directly to the spark plug, so a secondary high voltage is applied to the spark plug. In this way, since the secondary high voltage is applied at a point different from the normal ignition timing, if this secondary high voltage breaks and ignites, there is a possibility that an irreversible problem will occur for the engine. Most rotary power distribution devices using a distributor usually have a constant closing angle, and the ignition coil is turned on approximately halfway between the power distribution terminals of each cylinder (an angle equivalent to the closing angle).
At that time, there is a relatively large air gap between the rotor and the power distribution terminal, so there is almost no possibility that the spark plug will break, but it is not impossible. In addition, in an ignition system with closed angle control, the position of point b shown in Figure 1 can occur at any position between point a and point 0, and the spark plug may break due to insufficient air gap. There is a high possibility that the engine will malfunction, and for this reason, it will be necessary to take measures to withstand voltage, such as increasing the diameter of the high-voltage power distribution part of the distributor. Further, in the case of a spark plug directly connected to the spark plug, it goes without saying that problems may occur due to the secondary high voltage generated when the spark plug is turned on. Furthermore, such problems tend to occur as the secondary voltage increases and the winding ratio increases as the performance of the ignition device increases, and an increase in the secondary high voltage is unavoidable. For engines, the possibility of malfunctions caused by secondary high voltages is even greater.

The inventors confirmed that the ignition plug breaks due to the secondary high voltage generated in the ignition coil, and the results show that the arc time, arc current, and arc are almost the same as the break at normal ignition timing. Energy is confirmed together, and if a break occurs, the engine will malfunction. The secondary high voltage waveforms when turned ON and when turned OFF to interrupt the primary current of the ignition coil and break,
Figure 3 shows the arc current waveform. The condition of the engine malfunction is shown in the engine acupressure diagram in Figure 4. Under normal conditions, the pressure peak point appears approximately 100 degrees after top dead center, as shown by the solid line, whereas in the pressure waveform that breaks when the ignition coil is turned on, the pressure peak point appears approximately at top dead center, as shown by the broken line. The pressure value will also be about 2 to 3 times higher than normal, and the rate of pressure increase will naturally increase. When such a defective waveform occurs, the engine torque not only decreases rapidly, but also causes abnormal vibrations and the like, resulting in serious drawbacks such as destruction of the engine. Furthermore, there is a serious drawback that phenomena such as knocking and afterburn may occur.

Conventionally, in order to eliminate the above-mentioned drawbacks, it has been considered to provide an additional circuit to the circuit that intermittents the primary current of the ignition coil to slow the rise of the secondary current (for example, Although this method can reduce the secondary voltage when the ignition coil is turned on, it is still insufficient because it cannot prevent the secondary voltage from occurring.

Therefore, the present invention reliably prevents the ignition plug from erroneously igniting when the ignition coil is turned on without providing an external additional circuit.
This allows the engine to operate safely.

[Means for solving problems]

Therefore, the present invention has a switching means that opens and closes in synchronization with the rotation of the internal combustion engine, a primary current that flows only in one direction by opening and closing the switching means, and a high voltage terminal only at one end of the secondary side. The other end of the secondary side is connected to an ignition coil connected to the low voltage side, and the high voltage terminal of this ignition coil is connected to generate an ignition spark by the high voltage generated on the secondary side of the ignition coil when the switching means is opened. an ignition plug inserted and connected only between one end of the secondary coil and the high voltage terminal on the secondary side of the ignition coil, and when the switching means is closed, a transient voltage is applied to the secondary side of the ignition coil. an internal combustion engine ignition device comprising: a high-voltage diode that prevents high voltage generated by the spark plug from being applied to the spark plug; and the high-voltage diode is integrally insulated and provided within the ignition coil. It provides:

[Effect]

As a result, the secondary voltage generated on the secondary side of the ignition coil when it is ON is blocked by the high voltage diode that is integrally provided within the ignition coil and is not applied to the high voltage terminal, which is twice the normal ignition timing when it is OFF. The next voltage is supplied to the spark plug via a high voltage diode and a high voltage terminal.

(Example〕 The present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 5, 1 is an alternating current generator that serves as an ignition signal generator that generates a signal synchronized with the rotation of the internal combustion engine, 2 is a waveform shaping circuit that shapes the waveform of the alternating current signal, 3 is a battery that serves as a power source, and 4 is a battery that serves as a power source. The ignition coil has a primary coil 4a and a secondary coil 4b.

5 is an external resistor for limiting the primary current of the primary coil 4a of the ignition coil 4, and 6 is a switching circuit that amplifies the ignition signal from the waveform shaping circuit 2 and connects and disconnects the primary coil 4a of the ignition coil 4. 7 is a high voltage diode, 8 is an ignition coil 4
A spark plug 8 is connected to one end of the secondary coil 4b via a distributor (not shown) so that a negative voltage is applied to the spark plug 8 during normal ignition.

Describing the detailed circuits of the waveform shaping circuit 2 and the switching circuit 6, 9 is a temperature compensation diode, 10 is
12 is a bias resistance of the transistor 11, and 13 is a load resistance of the transistor 11. 14 is a constant voltage diode, 15
16 is a noise absorbing capacitor, and 16 is a dropper resistor for a constant voltage circuit. 17 is a base resistance of the transistor 18, 19 is a load resistance of the transistor 18, 20 is a current amplification transistor, 21 is a load resistance of the transistor 20, 2
2 is an oscillation prevention capacitor, and 23 is a power transistor as a switching means for turning on and off the primary side of the ignition coil 4, which is a Darlington transistor. 2
4 is a base-emitter resistance of the power transistor 23, and 25 is a Zener diode for voltage protection of the power transistor 23. 26 is a Zener diode for voltage protection protection of the power transistor 23, and its Zener voltage is set to about 350V.

Next, the operation of the above configuration will be explained.

The sixth AC signal generator 1 synchronizes with the rotation of the internal combustion engine.
An alternating current signal shown in FIG. 6(A) is generated, and based on this signal, the waveform shaping circuit 2 obtains a rectangular wave output shown in FIG. 6(B), and this rectangular wave output causes the primary coil 4a to
- Turns the OFF power transistor 23 ON and OFF. In the waveform of the AC signal generator l shown in FIG. 6(A), normally between a and b the transistor 11 is OFF, the transistor 18 is ON, the transistor 20 and the power transistor 23 are both OFF, and between b and c The above ON-OFF state is reversed, and the power transistor 23 is finally turned ON. FIG. 6(C) shows the collector waveform of the power transistor 23.

Points a and c in Figure 6 (8) are the normal ignition timing,
Since the secondary side is connected to the lower terminal of both terminals of the secondary coil 4b so that a negative high voltage is generated,
It is in the forward direction with respect to the high voltage diode 7, and when the power transistor 23 is OFF, the spark plug 8 breaks and ignites.

At point b, the power transistor 23 is turned on, but
Although a secondary high voltage is generated as described above at this ON time, the secondary high voltage generated at point b generates a voltage in the secondary coil 4b with a polarity opposite to that of the normal ignition timing as described above. A positive high voltage is generated at the lower terminal. Therefore, the voltage is reverse to the high voltage diode 7, and if the high voltage diode 7 is not present, the secondary high voltage applied to the spark plug 8 can be blocked by the high voltage diode 7. can be prevented from breaking. It is sufficient that the high voltage diode 7 has a withstand voltage equal to or higher than the withstand voltage of V2 at the point shown in FIG. 1, but in this embodiment, a high voltage diode with a reverse withstand voltage VRM=4 KV is used. FIG. 6(D) shows the waveform of the lower terminal of the secondary coil 4b (i.e., negative high voltage terminal) when the high voltage diode 7 is inserted, and FIG. 6(E) shows the waveform when the high voltage diode 7 is not inserted. The same waveforms as above are shown for the case. As can be seen from the waveforms (D) and (E) in FIG. 6, by using the high voltage diode 7, it is possible to reliably prevent the secondary high voltage generated when the spark plug is turned on from being applied to the spark plug 8. I can do it.

FIG. 7 shows an ignition coil according to the embodiment shown in FIG. 5, in which a high voltage diode 7 is integrated into the ignition coil 4. As shown in FIG. In FIG. 7, reference numeral 3o denotes an iron core constituting a magnetic circuit, which is of a closed magnetic circuit type, and is constructed by punching out cores in a figure 8 shape and stacking them.

31 are low voltage terminals provided at both ends of the primary coil 4a.

32 is a high voltage terminal provided at one end of the secondary coil 4b;
A negative secondary voltage is generated at the high voltage terminal 32 during normal ignition. The anode side of the high voltage diode 7 is connected to the high voltage terminal 32, and the cathode side is connected to one end of the secondary coil 4b.

The other end of the secondary coil 4b is connected to one end (low voltage side) of the primary coil 4a. 36 is a case which is bolted and fixed with epoxy resin 37.

As shown in FIG. 7, the high voltage diode 7 is connected to the ignition coil 4.
Since it is potted in the same case 36 with epoxy resin 37, there is no possibility of leakage along the surface of the high voltage diode 7, etc., and there is an excellent feature that a small and lightweight ignition coil can be provided.

〔Effect of the invention〕

As described above, in the present invention, the ignition coil is
The secondary high voltage that occurs when the ignition coil is turned on is blocked by the high voltage diode that is built into the ignition coil, ensuring that the spark plug will not break due to the secondary high voltage that is generated when the ignition coil is turned on. This has the excellent effect of preventing malfunctions to the internal combustion engine caused by this break, and allowing the internal combustion engine to be operated safely without providing an external additional circuit.

Furthermore, on the secondary side of the ignition coil, one end is connected to the low voltage side, and the high voltage diode is connected only between the other end of the secondary coil and the high voltage terminal, so wiring is not only simple and inexpensive, but also Since the reverse polarity voltage generated on the high voltage terminal side of the ignition coil is reliably blocked by the high voltage diode, it is possible to reliably prevent the reverse polarity voltage from being applied to the high voltage terminal itself.

In addition, conventionally, the purpose of distributing high voltage to the spark plugs of each cylinder without using a distributor was
It has been considered that a primary current is passed alternately between positive and negative through a double ignition coil, and high voltage is generated alternately between positive and negative on the secondary side of the ignition coil, and the high voltage is distributed to each spark plug via each high-voltage diode ( For example, Japanese Patent Application Laid-Open No. 50-43327), but in this case, the secondary voltage generated when the ignition coil is turned on is applied to the spark plugs of other cylinders, which may cause the spark plugs to break. However, the above-mentioned effects unique to the present invention cannot be exhibited at all.

[Brief explanation of drawings]

Figure 1 is a diagram of the secondary high voltage waveform generated on the secondary side of a general ignition coil, Figure 2 is a diagram of secondary high voltage generation characteristics when the coil is turned on due to the ignition coil and power supply voltage, and Figure 3 is a diagram of the secondary high voltage generation characteristic of the ignition coil and power supply voltage. Figure 4 shows the secondary voltage and arc current waveform diagrams during normal ignition and when the coil is ON when there is a break.
5 is an electric circuit diagram showing one embodiment of the device of the present invention; FIG. 6 is a waveform diagram of each part to explain the operation of the device shown in FIG. 5; FIG. 7 is a diagram of the above-mentioned implementation. It is a longitudinal cross-sectional view showing an ignition coil applied to an example. 4...Ignition coil, 7...High voltage diode, 8...
- Spark plug, 23... Power transistor as switching means, 32... High voltage terminal. Representative Patent Attorney Takashi Okabe OFF ON OFF
F Figure 1 @ Miku Electric Works Figure 2 Figure 3 (TDC)

Claims (1)

[Claims] A switching means that opens and closes in synchronization with the rotation of the internal combustion engine, and a primary current that flows in only one direction is interrupted by opening and closing of this switching means, and has a high voltage terminal only at one end of the secondary side, and has a high voltage terminal at one end of the secondary side. an ignition coil whose end is connected to a low voltage side; an ignition plug that is connected to a high voltage terminal of the ignition coil and generates an ignition spark by a high voltage generated on the secondary side of the ignition coil when the switching means is opened; The secondary side of the ignition coil is inserted and connected only between one end of the secondary coil and the high voltage terminal, and is connected to the high voltage terminal that transiently occurs on the secondary side of the ignition coil when the switching means is closed. An internal combustion engine ignition device comprising: a high-voltage diode that prevents voltage from being applied to the spark plug, the high-voltage diode being integrally and insulated within the ignition coil.