JPS6145345Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a non-contact ignition device for an internal combustion engine, and more particularly to a non-contact ignition device for an internal combustion engine that aims to reduce radio noise generated during ignition.

[Conventional technology]

Fig. 1 shows the circuit configuration of a conventional non-contact ignition device of this type. An ignition circuit 2 for switching the alternating current signal is connected to the output end of the machine. In the ignition circuit 2, 3 and 4 are surge absorption capacitors, 5 is a current limiting resistor,
6 is a power transistor, and the collector of the transistor 6 is connected to the primary coil 7 of the ignition coil 7.
a. Connected to the anode of the battery 8 via the power line 13.

Further, one end of the secondary coil 7b of the ignition coil 7 is connected to an anode of a battery 8 via a power line 13, and the other end is connected to an engine ground 10 via a spark plug 9. Further, the cathode of the battery 8 is connected to a body ground (referring to the body itself) 11 and also to an engine ground 10 via a wire 12.

Further, one ends of the primary coil 7a and the secondary coil 7b of the ignition coil 7 are connected in common, and are connected to one end of the capacitor 3 via a power supply line 14. Here, in order to simplify the explanation, the description of the destination viewer provided between the ignition coil 7 and the spark plug 9 is omitted.

In the above configuration, when an AC signal synchronized with engine rotation is output from the AC generator 1, the ignition circuit 2 switches the AC signal, and the primary current flows through the power transistor 6 to the primary coil 7a of the ignition coil 7. intermittent.

As a result, a high voltage is generated in the secondary coil 7b of the ignition coil 7, and an ignition spark is generated in the ignition plug 8.

Here, the capacitors 3 and 4 in the ignition circuit 2 absorb a surge such as a leakage spark from the ignition coil 7 when it is applied to the ignition circuit 2 via the power line 14, and 5, and is inserted for the purpose of preventing deterioration or destruction of a semiconductor element or resistor (not shown) due to the above-mentioned surge.

In the conventional device shown in FIG. 1, the spark current generated in the ignition plug 9 is caused by the ignition coil 7→power line 13→battery 8→wire 12→spark plug 9 because the power line 13 has inductance.
→It does not flow through the path of the ignition coil 7, and most of it flows through the path of the ignition coil 7 → power line 14 → capacitor 3 → body 11 → wire 12 → spark plug 9 → ignition coil 7. At this time, the spark current flowing through the power supply line 14 and the body 11 generates radio noise.

In addition, when the capacitor 3 is removed in the conventional device shown in FIG. 1, the spark current is changed due to the current limiting resistor 5 from the ignition coil 7 → power line 14 → resistor 5 → capacitor 4 → body 11 → wire 12 → spark plug 9 →
It is difficult for the flow to flow through the ignition coil 7 path, and most of it flows from the ignition coil 7 → power line 13 → battery 8 →
It flows through the path of wire 12 → spark plug 9 → ignition coil 7.

Therefore, since the spark current flowing through the power line 13 does not pass through the body 11, the generated radio noise is reduced compared to the case where the spark current flows through the power line 14 and the body 11.

However, as described above, when a surge voltage such as a leakage spark from the ignition coil 7 is applied to the ignition circuit 2 via the power supply line 14, the ignition circuit 2
This has the disadvantage that it causes deterioration or destruction of the internal resistor 5 and semiconductor elements and resistors (not shown).

Next, an improved example of the conventional device shown in FIG. 1 is shown in FIGS. 2 and 3. The non-contact ignition device shown in FIG. 2 is structurally different from the conventional device shown in FIG. Primary coil 7a of coil 7
A capacitor 21 is connected between the common connection part of the secondary coil 7b and the engine ground 10, and the other configurations are completely the same.

Note that the line 16 is shown to be connected through the engine body.

In this example, since the battery voltage applied to the Zener diode 15 is normally lower than the Zener voltage, the Zener diode 15 is in a cut-off state.

Therefore, most of the spark current generated in the ignition coil 7 during ignition flows from the ignition coil 7 to the capacitor 21 to
It flows through the engine body → spark plug 9 → ignition coil 7, and radio noise is reduced compared to when it flows through other routes.

Furthermore, when a surge voltage higher than the Zener voltage of the Zener diode 15 is applied to the ignition circuit 2, the Zener diode 15 absorbs the surge voltage and protects the ignition circuit 2 from the surge voltage.

[Problem that the invention attempts to solve]

However, this example has the disadvantage that if the battery is accidentally reversely connected in the vehicle, the Zener diode 15 will be short-circuited and destroyed.

FIG. 3 shows an improved example of the non-contact ignition device shown in FIG. 2, and the difference in configuration from the ignition device shown in FIG. diode 17,
18 was inserted, and the other configurations are exactly the same.

In the figure, it is assumed that the Zener diodes 17 and 18 have the same characteristics, and if their Zener voltage is V _z and the forward voltage drop is V 〓, then ±(V
The surge voltage and battery voltage are clipped at the voltage _z + V〓).

Therefore, even if the battery 8 is reversely connected as in the improved example shown in FIG. 2, the Zener diode will not be damaged by short circuit.

However, in the case of this example, two Zener diodes are required, which increases the cost and increases the storage space for the ignition circuit.

[Purpose of the invention] The purpose of the invention is to reduce the radio noise generated during ignition, protect the ignition circuit itself from surge voltages generated by ignition coils, etc., and protect the semiconductors constituting the ignition circuit that may be caused by incorrect battery connection. An object of the present invention is to provide an ignition device for an internal combustion engine that prevents deterioration and destruction of elements and the like.

[Means for solving problems]

The feature of this invention is that the current flowing through the primary coil of the ignition coil is switched to generate a high voltage in the secondary coil of the ignition coil to generate an ignition spark. A series circuit of a Zener diode and a capacitor having a Zener voltage higher than the voltage of the power supply line between a power supply input terminal and a ground terminal in an ignition circuit, and a capacitor connected between the power supply line and the engine ground; The point is that the limiting resistor and the series circuit of the capacitor are connected in parallel.

〔Example〕

An embodiment of the ignition system for an internal combustion engine according to the present invention is shown in FIG. This embodiment differs in structure from the improved example shown in FIG. 3 in that a series circuit of a Zener diode 19 and a capacitor 20 is used instead of the Zener diodes connected in series in opposite directions between the power supply line 14 and the body ground 11. Since the other configurations are exactly the same, a redundant explanation of the operation will be omitted.

In FIG. 4, the normal spark current in the spark plug 9 that occurs during ignition is due to the inductance and resistance 5 of the power line 13. And ignition coil 7 → power line 14 → resistor 5 → capacitor 4 → body 11 →
It is difficult to flow in the path of wire 12 → spark plug 9 → ignition coil 7, and most of the flow is from ignition coil 7 → capacitor 21 → engine body 16 → spark plug 9
→It flows through the path of the ignition coil 7, and the generated radio noise is reduced compared to when it flows through other paths.

Further, when a surge voltage higher than the Zener voltage of the Zener diode 19 is applied to the ignition circuit 2, the surge voltage is absorbed by the Zener diode 19, and the ignition circuit 2 is protected from the surge voltage.

Furthermore, if the battery 8 is incorrectly connected, the capacitor 20 protects the Zener diode 19 from conduction breakdown, and in the case of this embodiment,
Since only one Zener diode is required, the storage space for the ignition circuit is small.

Incidentally, to give an example of circuit constants, the battery voltage is
For 12V, select Zener voltage between 18 and 24V,
Capacitor 20 is 0.1μF or less, capacitor 21
By setting it to about 0.5 μF, a normal spark current can flow through the circuit of the capacitor 21, and a small forward surge in energy can be sufficiently absorbed, and destruction of the Zener diode due to reverse current can be sufficiently prevented. can.

[Effect of idea]

As explained above, according to the present invention, it is possible to reduce radio noise caused by spark current generated during ignition, protect the ignition circuit from surge voltage, and prevent deterioration and destruction of the protection circuit due to reverse battery connection. It is possible to realize a non-contact ignition system for an internal combustion engine.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the configuration of a conventional non-contact ignition device for an internal combustion engine, Figs. 2 and 3 are circuit diagrams showing an improved example of the conventional device in Fig. 1, and Fig. 4 is a circuit diagram showing an improved example of the conventional device in Fig. 1. FIG. 2 is a circuit diagram showing the configuration of a non-contact ignition device for an internal combustion engine. 1... Alternator, 2... Ignition circuit, 7... Ignition coil, 9... Spark plug, 19... Zener diode, 20... Capacitor.

Claims (1)

[Scope of utility model registration request] An alternator that generates an alternating current signal synchronized with engine rotation, an ignition circuit that switches the alternating current signal, an ignition coil connected to the output end of the ignition circuit, and an ignition coil connected in series to the secondary side of the ignition coil. The non-contact ignition device for an internal combustion engine includes an ignition plug whose one end is connected to engine ground, generates high voltage on the secondary side of the ignition coil, and generates an ignition spark at the ignition plug. A capacitor is connected between the power supply line of the coil and the engine ground, and a Zener diode having a Zener voltage higher than the voltage of the power supply line is connected in series with the capacitor between the power input terminal and the ground terminal in the ignition circuit. A non-contact ignition device for an internal combustion engine, characterized in that a circuit is connected in parallel with a series circuit of a current limiting resistor and a capacitor.