JPS5846676B2 - Ignition system for internal combustion engines - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ignition device for an internal combustion engine.

Conventionally, an ignition system for an internal combustion engine uses a method in which an ignition coil generates high voltage, and a distributor distributes it to the spark plugs of each cylinder of the internal combustion engine (hereinafter referred to as engine).

This method has the drawbacks of generating high frequency noise from the disk I-IJ computer and being expensive due to the large number of parts.

On the other hand, 2
It has a secondary winding, and both ends of this secondary winding are installed in two cylinders with opposite strokes (in a 4-cycle engine, if the first cylinder is in the compression stroke, the second cylinder is in the exhaust stroke). A method is being considered in which the spark plug is connected to two spark plugs and the two spark plugs are used to simultaneously ignite the spark (hereinafter referred to as a double coil ignition method).

However, in the conventional double-coil ignition system described above, since the secondary winding has two spark plugs (or discharge gaps) in series, the discharge end time is dependent on the relationship between the conditions between the two discharge gaps. Slightly different depending on the product.

That is, even after the first discharge gap finishes discharging, the second discharge gap continues discharging for a while, charging the stray capacitance between the secondary winding and the engine to a positive or negative potential.

Since the secondary winding does not have a DC return path between it and the engine, the charging potential of the secondary winding is preserved until the time when energization of the primary winding starts.

Next, when the primary winding starts to be energized, a voltage corresponding to the voltage applied to the primary winding and the winding ratio is generated across both ends of the secondary winding.

That is, the potential of the first spark plug is twice the charging potential compared to the potential of the second spark plug.

As a result, the first or second spark plug starts discharging even when the primary winding is energized.

By the way, since either the first spark plug or the second spark plug is always in the cylinder during the intake or compression stroke, the discharge at the start of energization has the serious drawback of causing backfire or pre-ignition. have

In order to solve the above-mentioned drawbacks, the present invention connects the secondary winding of an ignition coil having a secondary winding that does not have a DC return path with the engine with a high resistance. , an ignition device for an internal combustion engine that can quickly reduce the charging potential of the secondary winding to prevent discharge at the spark plug when the primary winding of the ignition coil is energized, which causes backfire or pre-ignition; The purpose is to provide the following.

An embodiment of the present invention will be described below with reference to the drawings.

In the accompanying drawings, 10 indicates a primary winding 11 and a secondary winding 12 with both ends open and having a stray capacitance of 13° 14 between ground and ground.
21.22 is an ignition coil installed in cylinders with different strokes and connected to both ends of the secondary winding 12; 31.32 is an ignition coil having the secondary winding 12;
It has a high resistance and serves as a direct current return path between the engine ground 44 and the engine ground 44.

Reference numerals 41 and 42 are contact points and capacitors for intermittent current flowing through the primary winding 11, and 43 is a battery.

In the above configuration, first, when the contact point 41 is closed, current flows through the primary winding 11 and magnetic energy is accumulated within the ignition coil 10.

Next, when the contact point 41 is closed, a high voltage is generated across the secondary winding 12, and discharge begins at each spark plug 21, 22 connected to both ends of the secondary winding 12, causing the above-mentioned Electromagnetic energy is released.

At this time, set the value of high resistance 31.32 to a sufficiently large value (IO
(about MΩ), the existence of these high resistances 31 and 32 can be ignored.

When the discharge starts at the spark plugs 21 and 22, the airflow, pressure, etc. in each engine cylinder vary irregularly, so the end time of the discharge differs between the spark plugs 21 and 22.

Now, assuming that the discharge on the spark plug 21 side ends first, the electric charge that flows into the secondary winding 12 through the spark plug 22 during the time from the end of the discharge of the spark plug 21 to the end of the discharge of the spark plug 22 causes The stray capacitances 13 and 14 are charged to a positive or negative potential depending on the sign of the charge.

Here, since the high resistance 31.32 is connected in parallel to the stray capacitance 13.14, the stray capacitance 13.
．． The charging potential of 14 quickly decreases.

In the above-described embodiment, the present invention is applied to a device in which the primary current of the ignition coil 10 is switched on and off using the contact point 41, but the present invention can also be applied to a device in which the primary current of the ignition coil 10 is switched on and off using a transistor. Of course, it can be applied.

As described above, in the device of the present invention, there is provided an ignition coil having a secondary winding connected to two spark plugs installed in different cylinders and having no DC return path with the engine; Since it includes at least one high resistance that connects the wire and the engine, the stray capacitance between the secondary winding and the engine can be discharged by the high resistance without adversely affecting the secondary generated voltage. This has the remarkable effect of eliminating discharge at the spark plug when the primary winding of the ignition coil is energized, which causes backfire and pre-ignition.

[Brief explanation of drawings]

The accompanying drawing is an electrical wiring diagram showing one embodiment of the device of the present invention. 10...Ignition coil, 12...
...Secondary winding, 13, 14... Stray capacitance, 21
, 22... Spark plug, 31, 32... High resistance, 44... Engine ground.

Claims (1)

[Claims] 1. Two spark plugs installed in different cylinders, an ignition coil that has a secondary winding with no direct current return path between the spark plugs and the ground, and the secondary winding of the ignition coil. An ignition device for an internal combustion engine, comprising: a high resistance connected between the ignition device and ground.