JPH0347475A - Ignition coil - Google Patents

Abstract

PURPOSE:To provide possibility of compatible use of a plug type head terminal and an M4 screw type head terminal without causing increase in the price by dimensioning specifically the gap between the periphery of a coil spring and the inside surface of a high voltage tower and a high voltage terminal and also the gap between element wires of the coil spring in a plane. CONSTITUTION:The gap between element wires of a coil spring 6 constituting a spiral part shall be smaller than 4mm. This coil spring 6 is formed with such a dia. that the gap between the inside surface of a cylindrical part 4a and the periphery of spring in a plane including said spiral part is smaller than 4mm. In an ignition coil 1, therefore, any gap larger than the outside dia. of an M4 screw type head terminal 5 can be eliminated in the plane including the spiral part of the foremost end of the spring 6. Also in a high voltage tower 3, accordingly, the head terminal 5 of an ignition plug 2 will never intrude into the gap between the periphery of the spring 6 and the inside surface of the cylindrical part 4a nor be inserted into the bore of the spring 6 when the coil 1 is fitted to the ignition plug 2 while fitted to a connection cap, and stable contact with the spring 6 is secured by pressing the spiral part of the spring 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition coil that is directly attached to an ignition plug of an internal combustion engine.

[Prior Art] As mentioned above, when attaching the ignition coil directly to the ignition hydrant, the connection structure between the high voltage terminal of the ignition coil and the head terminal of the ignition hydrant depends on the type of the head terminal of the ignition hydrant. different.

There are two types of head terminals for spark plugs: bullet type head terminals (hereinafter abbreviated as bullet terminals) with a head outer diameter of φ6.4 and M4 screw type head terminals (hereinafter abbreviated as M4 terminals).

For example, a connection structure between an ignition plug and an ignition coil using a bullet terminal includes a cup-shaped high voltage terminal 102 connected to a secondary coil inside a high voltage tower 101 of an ignition coil 100, as shown in FIG. By burying the spark plug 200 and inserting the bullet terminal 201 of the spark plug 200 into the high voltage terminal 102,
The high voltage terminal 102 and the bullet terminal 201 are electrically connected to each other.

Alternatively, as shown in FIG. 5, when assembling, a conductive coil spring 300 is inserted between the high voltage terminal 102 and the bullet terminal 201 to absorb the dimensional tolerance and obtain a stable electrical connection. There is a connection structure with .

On the other hand, the connection structure between the ignition plug 200 and the ignition coil 100 using the M4 terminal 202 is as shown in FIG.
02 and bring the outer circumference of the M4 terminal 202 into contact with the inner diameter of the coil spring 300.
02 and the M4 terminal 202 are electrically connected.

[Problems to be Solved by the Invention] However, as described above, the connection structure of the high voltage terminal 102 of the ignition coil 100 is different between the bullet terminal 201 and the M4 terminal 202.
It is not possible to use both with 02.

That is, when the M4 terminal 202 is applied to the connection structure for the bullet terminal 201 shown in FIG. φ64, M4 terminal 202
:φ4), cup-shaped high voltage terminal 102, M4 terminal 202
A space is created between the outer periphery of the spark and a spark discharge occurs in that space. As a result, problems such as generation of harmful radio noise and wear of the head terminal due to discharge occur.

Furthermore, when the M4 terminal 202 is applied to the connection structure for the bullet terminal 201 shown in No. 5t171, the M4 terminal 202 and the coil spring 300 may be connected with misalignment or eccentricity between the two. , the M4 terminal 202 is connected to the inner diameter part of the coil spring 300 or the coil spring 3.
00 and the high pressure tower 101. Therefore, the M4 terminal 202 and the coil spring 300
Contact becomes unstable.

On the other hand, connect the bullet terminal 201 to the M4 terminal 2 shown in FIG.
When applied to the connection structure for 02, the inner diameter of the drum-shaped coil spring 300 does not match the bullet terminal 201, and if it is forcibly inserted, the coil spring 3
00 is crushed and transformed.

Therefore, as shown in FIG.
A conductive contact (carbon, aluminum, etc.) 400 is attached to the end of the contactor 400, and by contacting the end surface of the bullet terminal 201 or the M4 terminal 202, stable contact can be obtained, and the bullet terminal 20
There is a connection structure that allows both the 1 and M4 terminals 202 to be used.

However, in this case, the cost increases due to the addition of the contactor 400. Furthermore, as the weight of the spring system increases, the natural frequency of the spring system decreases, leading to a decrease in vibration resistance. In other words, when the spring system resonates with the vibration frequency of the engine, which is the source of vibration, mechanical abrasion of the various contact parts and contact failure due to the contact 400 flying off may occur, and if used under such conditions, spark discharge may occur. will occur.

Therefore, this spark discharge causes problems such as generation of radio wave noise and wear of the head terminal.

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to connect bullet terminals and M4 without increasing costs.
An object of the present invention is to provide an ignition coil that can be used for both purposes as a terminal. [Means for Solving the Problems] In order to achieve the above object, the present invention embeds a high-voltage terminal to which a high voltage is applied, and An ignition coil in which a conductive coil spring for electrically connecting the head terminal and the high voltage terminal is disposed in an insulating high voltage tower into which the head terminal of the ignition plug is inserted, the coil spring being , a gap between the outer circumference of the coil spring and the inner circumferential surface of the high voltage tower or the inner circumferential surface of the high voltage terminal is provided to be smaller than 4 mm in a radial plane at the end on the head terminal side; The end of the coil spring on the terminal side is spirally or bent in the plane, and the distance between the strands of the coil spring in the plane is smaller than 4 mm (providing this is considered a technical means). .

Function and Effects of the Invention] The ignition coil of the present invention having the above-described configuration has the outer periphery of the coil spring and the inner periphery of the high voltage tower or the inner periphery of the high voltage terminal within a plane at the head terminal side end of the coil spring. The gap with the surface is set to be smaller than 4 mm.

Further, the end portion of the coil spring on the head terminal side is formed in a spiral shape or bent, and the interval between the strands of the coil spring in the plane is set to be smaller than 4 mm.

Therefore, within the plane at the head terminal side end of the coil spring, there is no gap larger than the outer diameter of the M4 screw type head terminal. As a result, even when the ignition coil of the present invention is applied to an ignition plug using an M4 screw type head terminal, stable contact between the M4 screw type head terminal and the coil spring can be achieved without using a conventional contactor. can be obtained. As a result, the ignition coil of the present invention can be used for both M4 screw type head terminals and bullet type head terminals having a larger head outer diameter than the M4 screw type head terminals, without increasing costs. .

[Example] Next, the ignition coil of the present invention will be explained based on an example shown in the drawings.

FIG. 1 is a sectional view of a main part of an ignition coil and a side view of a spark plug.

The ignition coil 1 of this embodiment is directly attached to the ignition plug 2 assembled to the cylinder head (not shown), and is made of rubber and attached to the head side (upper side in Figure 1) of the ignition plug 2. A connection cap (not shown) and a high voltage tower 3 of the ignition coil 1 are provided to fit together.

A high voltage terminal 4 to which a high voltage is applied from a secondary coil (not shown) is embedded in the high voltage tower 3 made of resin.

The high voltage terminal 4 has a cylindrical shape on the spark plug 2 side (lower side in Figure 1), and when the high voltage tower 3 is fitted into the connection cap, the spark plug is inserted into the cylindrical portion 4a of the high voltage terminal 4. The tip of the cylindrical portion 4a is provided close to the end surface of the high voltage tower 3 so that the second head terminal (M4 screw type head terminal) 5 can be inserted.

As a result, since the outer periphery of the head terminal 5 is surrounded by the inner wall of the high voltage terminal 4, even if spark discharge occurs between the high voltage terminal 4 and the head terminal 5, creeping discharge that propagates along the inner wall surface of the high voltage tower 3 The high pressure tower 3 made of resin prevents
It is possible to prevent erosion of the inner wall surface.

Inside the cylindrical portion 4a of the high voltage terminal 4, there are the high voltage terminal 4 and the cylindrical portion 4a.
A conductive coil spring 6 is provided for electrical connection with the head terminal 5 inserted therein.

Therefore, when the high-voltage tower 3 of the ignition coil 1 is fitted into the connection cap of the ignition plug 2, the head terminal 5 of the ignition plug 2 is inserted into the cylindrical portion 4a of the high-voltage terminal 4 with the coil spring 6 compressed. inserted into.

The coil spring 6 has a slightly larger coil diameter at the bottom end (upper side in FIG. 1), and is inserted into the cylindrical portion 4a from the bottom side and pressed from the tip side.
The bottom side end portion of the coil having a large diameter is engaged with a large diameter portion 4b formed at the inner bottom of the cylindrical portion 4a, and is assembled into the cylindrical portion 4a. At this time, by inserting the coil spring 6 while rotating it in the opposite direction to the winding direction, it can be easily assembled into the cylindrical portion 4a.

As shown in FIG. 2, the tip end of the coil spring 6 is formed in a spiral shape toward the inner periphery, and is configured as a contact surface with the head terminal 5.

The interval between the wires of the coil spring 6 forming the spiral portion is set to be smaller than 4 mm. Further, the coil spring 6 is formed to have a coil diameter such that the gap between the outer circumference of the coil spring 6 and the inner circumferential surface of the cylindrical portion 4a in a plane including the spiral portion is smaller than 4 mm.

As a result, the above-mentioned ignition coil 1 can be configured to
A gap larger than the outer diameter of the M4 screw type head terminal 5 can be eliminated. Therefore, when the high voltage tower 3 is fitted into the connection cap and the ignition coil 1 is attached to the ignition plug 2,
The head terminal 5 of the ignition plug 2 does not enter the gap between the outer periphery of the coil spring 6 and the inner periphery of the cylindrical portion 4a or is inserted into the inner periphery of the coil spring 6. The spiral portion of the spring 6 can be pressed to ensure stable contact with the coil spring 6.

Therefore, the ignition coil 1 of this embodiment does not use a conventional conductive contactor (without increasing costs), and has a bullet-shaped head having a larger outer diameter than the M4 screw-type head terminal 5. It can also be applied to spark plugs using external terminals.

In addition, in order to prevent creeping discharge transmitted through the inner wall surface of the high-voltage tower 3, an example was shown in which the tip of the cylindrical portion 4a of the high-voltage terminal 4 was provided close to the end surface of the high-voltage tower 3; however, the cylindrical portion may be formed with a shallow depth. In the case of an ignition coil (see FIGS. 4 to 7), the gap between the outer circumference of the coil spring 6 and the inner circumferential surface of the high-pressure tower 3 is set in a plane that includes the spiral portion of the coil spring 6. It is necessary to provide the diameter smaller than 4 mm.

(Modification) In the above embodiment, the tip end of the coil spring 6 is formed in a spiral shape, but it may also be bent in a meandering shape as shown in FIG. Even in this case, the distance between the wires of the coil spring 6 bent in a meandering manner is set to be smaller than 4 mm.

[Brief explanation of drawings]

Figure 1 is a sectional view of the main parts of the ignition coil and a side view of the ignition plug, and Figure 2 is a top view of the tip side of the coil spring (Figure 1A
Fig. 3 is a front end side plan view showing a modified example of the coil ring, and Figs. 4 to 7 illustrate the prior art and show the connection structure between the ignition coil and the ignition plug. In the diagram 1...Ignition coil 2...Ignition plug 3...
・High voltage tower 4...High voltage terminal 5...
M4 screw type head terminal 6...Coil spring

Claims (1)

[Claims] 1) burying a high voltage terminal to which a high voltage is applied;
An ignition coil in which a conductive coil spring for electrically connecting the head terminal and the high voltage terminal is disposed in an insulating high voltage tower into which the head terminal of the ignition plug is inserted, the coil spring being , a gap between the outer circumference of the coil spring and the inner circumferential surface of the high voltage tower or the inner circumferential surface of the high voltage terminal is provided to be smaller than 4 mm in a radial plane at the end on the head terminal side; An ignition coil characterized in that an end portion on a terminal side is spirally or bent in the plane, and a distance between the strands of the coil spring in the plane is smaller than 4 mm.