JPH0192576A - Ignition system for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a compact ignition coil by connecting magnetically cores of respective ignition coils provided in respective ignition plugs of cylinders to each other to control the supply and interruption of current to the coil in the ignition of ignition plug other than that to be discharged. CONSTITUTION:In an embodiment of an ignition system of a three-cylinder engine is provided a core 10 having a pair of longitudinal portions 11, 12 extending parallel to each other, connections 13, 14 interconnecting both ends of said portions and a projection 15 projecting from the central portion of the longitudinal portion 11 toward the longitudinal portion 12. Also, from the central lower surfaces of respective connections 13, 14 and the lower surface of end of the projection 15 are extended downward core portions 16-18 the lower ends of which are magnetically interconnected with a connection 19 parallel to the longitudinal members 11, 12. the respective core portions 16-18 are wound respectively by primary and secondary coils covered by a resin case 21, and ignition plugs 31-33 are connected to the respective secondary coils. Also, the primary coil is connected to an ignitor through a connector 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition device between internal combustion engines that controls the discharge of a spark plug.

[Conventional technology and problems]

Conventionally, in order to discharge electricity to a predetermined spark plug, there is a configuration in which power is distributed from one ignition coil to the spark plug by a distributor (Japanese Patent Publication No. 55-42266);
An ignition coil is provided for each cylinder, and a high voltage is generated in the designated ignition coil.
6133, Japanese Patent Application Laid-open No. 193776/1983) are known. Of these, the latter is often adopted in the case of engines that do not have space to mount a distributor, and is preferable in terms of efficiency because it causes less loss of discharge energy.

However, in the case of an independent ignition system, the size of the ignition coil is limited because there is a space limit for mounting it on the top of the engine's cylinder head. Therefore, the independent ignition system is
There is a problem in that the ignition coil is required to be downsized, and the discharge energy and generated voltage of the ignition coil may not be sufficiently increased. In order to increase the generated voltage, etc., it is possible to increase the primary current to the ignition coil, but the capacity and withstand voltage of the power transistor for controlling the primary current are also limited, so it is necessary to make the generated voltage, etc. sufficiently high. That is difficult.

In view of the above points, the present invention has been made with the object of providing an ignition device that is compact and capable of obtaining sufficient discharge energy and generated voltage.

[Means for solving problems]

The present invention has a primary coil, a secondary coil, and a core part, and is used to generate high voltage in the ignition coil provided for each spark plug of each cylinder and the secondary coil of the ignition coil of the spark plug to be discharged. In the ignition system for an internal combustion engine, the core portions of the ignition coils are magnetically connected to each other, and the control circuit shuts off current to the primary coils of the ignition coils other than the spark plugs to be discharged. This method is characterized in that a high voltage is generated in the secondary coil of the ignition coil of the spark plug to be discharged.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 2 shows the appearance of an ignition device according to a first embodiment of the present invention. In this embodiment, the present invention is applied to a three-cylinder engine.

The core 10 has a pair of longitudinal parts 11° and 12 that extend parallel to each other.
, connecting portions 13 and 14 that connect both ends of these longitudinal portions 11 and 12, and a projection portion 15 that projects from the center of one longitudinal portion 11 toward the other longitudinal portion 12.

Core portions 16 , 17 , 18 extend downward from the center lower surface of each connecting portion 13 , 14 and from the lower end surface of the protruding portion 15 , and the lower end portion of each core portion 16 , 17 , 18 extends from the longitudinal portion 11 . , 12 are connected by a connecting portion 19 parallel to them. Therefore, each core part 16 , 17 , 18
are magnetically coupled to each other.

A primary coil and a secondary coil (not shown) are wound around each core portion 16 , 17 , 18 , respectively, and these coils are covered with a resin case 21 . A high voltage diode (not shown) is accommodated in the case 21 . The connector 22 is provided adjacent to each of the core portions 16, 17, and 18, and has terminals for connecting the primary coil and the secondary coil to a battery or igniter (not shown). Spark plugs 31, 32.

33 is disposed below each core portion 16 , 17 , 18 and is electrically connected to the secondary coil within the resin case 21 .

The rubber cap 34 covers the insulators of the spark plugs 31, 82, and 33 to prevent electrical leakage on the surfaces of the insulators.

Therefore, the primary coil, secondary coil and core section 16,
Ignition coils 17 and 18 are provided for each cylinder and are controlled independently, as will be described later.

FIG. 3 shows an electrical circuit diagram of this embodiment. The ignition coil 41 connected to the ignition plug 31 of the first cylinder is connected to the core portion 16.
It has a primary coil 42 and a secondary coil 43 wound around this core portion 16.

Similarly, the ignition coil 44 connected to the spark plug 32 of the second cylinder includes the core portion 17 and the primary and secondary coils 45.
, 46, and the ignition coil 47 connected to the ignition plug 33 of the third cylinder has a core portion 18 and primary and secondary coils 48, 49.

In the ignition coil 41, the primary and secondary coils 42
, 43 are interconnected and connected to the battery 51. Similarly, the primary and secondary coils 45 , 46 and the primary and secondary coils 48 , 49 are also connected to the battery 51 . Further, each primary coil 42 , 45 , 48 is connected to an igniter 52 . The igniter 52 is controlled by a control circuit 53 and energizes the primary coils 42 , 45 , 48 . In order to prevent spark plugs other than those to be discharged from being discharged due to the back electromotive force generated in the corresponding secondary coils 43, 46, 49 when power is cut off to the primary coils 42, 45, 48, each Secondary coil 4
3, 46, 49 and spark plugs 31, 32, 33
High voltage diodes 54, 55, and
56 are connected.

FIG. 1 shows the circuit diagram of FIG. 3 with a modified shape in order to make it easier to understand. The igniter 52 has power transistors 57, 58, 59 connected to the primary coils 42, 45, 48 of each ignition coil 41, 44, 47, respectively. The control circuit 53 applies and releases voltage to the bases of predetermined power transistors 57 , 58 , 59 , energizes and cuts off predetermined primary coils 42 , 45 , 48 , and controls the secondary spark plugs to be discharged. A high voltage is generated in the secondary coils 43, 46, and 49.

The operation of this embodiment will be explained with reference to FIG.

A case where the spark plug 33 of the third cylinder is caused to discharge will be explained. The control circuit 53 includes a power transistor 57,
A voltage is applied to the bases of the power transistors 57 and 58 to turn them on, and the ignition coils 41 and 58 are turned on.
The primary coils 42 and 45 of 44 are energized.

As a result, a magnetic flux A consisting of a closed curve is generated in the core 10 from the core part 16 through the core part 18 and returning to the core part 16 again, and from the core part 17 to the core part 18 and returning to the core part 17 again. A magnetic flux B consisting of a closed curve is generated. That is, a magnetic flux that is twice as strong as the magnetic flux generated in the core portions 16 and 17 is generated in the core portion 18 . When the base voltages of the power transistors 57 and 58 are released to cut off the current supply to the primary coils 42 and 45, a high voltage is generated in the secondary coil 48 of the ignition coil 47, thereby causing the spark plug 33 to discharge.

Comparing the voltage and discharge energy generated in the secondary coil 48 with those in a configuration in which only one primary coil is energized, the voltage is 77 times higher, the discharge energy is twice as high, and the spark plug 33 is reliably activated. This will result in a discharge. At this time, the secondary coil 4 connected to the spark plugs 31 and 32
3 and 46, a back electromotive force is generated in the opposite direction to the back electromotive force generated in the secondary coil 49 connected to the spark plug 33, but the spark plugs 31 and 32 are not discharged due to the high voltage diodes 54 and 55.

Similarly, to cause the spark plug 31 of the first cylinder to discharge, the primary coils 45 and 48 are energized and cut off, and the
The primary coil 42 is used to discharge the spark plug 32 of the cylinder.
, 48 may be turned on and off.

FIG. 4 shows a second embodiment. This example demonstrates the invention in four ways.
This is an example applied to a cylinder engine, that is, the spark plugs 31, 32, 33, and 34 are discharged. The core 10 has a core part 61 in addition to the core parts 16, 17, and 18, and this core part 61 has other core parts 1B,
17 and 18, a primary coil 62 and a secondary coil 63 are wound, and the core portion 61 and the primary and secondary coils 62 and 63 form an ignition coil 64. The primary coil 62 is connected to a power transistor 65 provided in the igniter 52.

Further, a high voltage diode 65 is provided between the secondary coil 63 and the spark plug 34.

In this embodiment, in order to discharge the spark plug 34, the primary coils 42, 45, and 48 of the ignition coils connected to the spark plugs 31, 32, and 33 are energized. As a result, the core part 61 of the ignition coil 64 connected to the spark plug 34 has other core parts 16,
A magnetic flux three times that generated at 17 and 18 is generated.

Therefore, when power to the primary coils 42, 45, and 48 is cut off, a high voltage is generated in the secondary coil 63 of the ignition coil 64, and the spark plug 34 is discharged.

The voltage and discharge energy generated in the secondary coil 63 are
Compared to the case where only one primary coil is energized, the voltage is twice as high and the discharge energy is three times as high.

As described above, the present invention can be used not only for engines with an odd number of cylinders but also for engines with an even number of cylinders.

〔Effect of the invention〕

As described above, according to the present invention, when an ignition coil of the same size as the conventional one is used, the generated voltage and discharge energy of the ignition coil become large. The ignition coil can be downsized and can be easily mounted on a vehicle.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing a first embodiment of the present invention, Fig. 2 is a perspective view showing the external appearance of the device of the first embodiment, and Fig. 3 is a perspective view of the core of the first embodiment. Electrical Circuit Diagram FIG. 4 is an electrical circuit diagram showing the second embodiment. DESCRIPTION OF SYMBOLS 10... Core, 16, 17, 18... Core part, 31, 32, 33, 34... Spark plug, 41
, 44 , 47 , 64 ... ignition coil, 42 ,
45, 48, 62...Primary coil, 43, 46
, 49, 63... Secondary coil, 53... Control circuit, 54, 55, 56, 65... High voltage diode.

Claims (1)

[Claims] 1. The ignition coil has a primary coil, a secondary coil, and a core part, and is provided for each spark plug in each cylinder, and a high voltage is applied to the secondary coil of the ignition coil of the spark plug to be discharged. In the ignition system for an internal combustion engine, the core portions of the ignition coils are magnetically connected to each other, and the control circuit is configured to control the primary ignition coils other than the spark plugs to be discharged. An ignition device for an internal combustion engine, characterized in that a high voltage is generated in a secondary coil of an ignition coil of a spark plug to be discharged by cutting off current to the coil. 2. A patent characterized in that a high-voltage diode is connected to each secondary coil to prevent the spark plug from discharging due to the back electromotive force generated in the secondary coil of the ignition coil whose primary coil is cut off. An ignition device according to claim 1.