JP2002081360A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition device for internal combustion engine having a connection structure with an ignition coil to an ignition plug making it hard to produce, by vibration, a variation in a contact resistance or interruption of a conductive route for applying an igniting high voltage produced by the ignition coil to the ignition plug. SOLUTION: A connection electrode 31 electrically connected to one end of the secondary winding of the ignition coil 27 is provided on the forward inner side of a casing part 33. The connection electrode 31 is formed into a cylindrical shape, and comprises an elastic part 31a formed in a curved shape having an elasticity in the radial direction toward the center axis of a cylinder. The incoming terminal 13 of the ignition plug 11 is inserted from the forward side of the casing part 33, and disposed in the cylindrical part 31d of the connection electrode 31. Thus, the incoming terminal 13 of the ignition plug 11 comes into contact with the connection electrode 31, and the incoming terminal 13 of the ignition plug 11 is electrically connected to one end 27a of the secondary winding of the ignition coil 27 to form the conductive passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug which is mounted on a cylinder of an internal combustion engine and generates a spark discharge for burning an air-fuel mixture, and a high ignition voltage for generating a spark discharge on the spark plug. The present invention relates to an ignition device for an internal combustion engine including an ignition coil that generates the ignition coil.

[0002]

2. Description of the Related Art An internal combustion engine such as a gasoline engine for an automobile or the like is operated using energy generated by combustion of an air-fuel mixture as a power source, and an ignition plug is used to ignite the air-fuel mixture.

[0003] Generally, a spark plug has a shaft-shaped center electrode inserted at the tip end of a shaft hole of an insulator, and one end connected to a metal shell provided on the outer periphery of the insulator, and the other end connected. A ground electrode is provided which is bent back to the side and whose side surface is opposed to the tip of the center electrode. Then, a spark discharge gap formed between the center electrode and the ground electrode is located in the combustion chamber, and the mixture is ignited by generating a spark discharge. The ignition plug is provided with a shaft-like power receiving terminal electrically connected to the center electrode at the rear end of the shaft hole of the insulator. When a high voltage is applied, a potential difference occurs between the center electrode and the ground electrode, and a spark discharge occurs in a spark discharge gap.

Here, in order to generate spark discharge in the ignition plug, it is necessary to form a conductive path for applying a high ignition voltage generated in the secondary winding of the ignition coil to the power receiving terminal of the ignition plug. . As a connection structure between the ignition coil and the ignition plug for forming a conductive path, as shown in FIG. 8, a conductive material electrically connected to one end of the secondary winding of the ignition coil 270 has conventionally been used. One end of the coil spring SP (coil spring) is pressed against one end 181 (rear surface) of the power receiving terminal 180 of the ignition plug 160,
A connection structure for securing a conductive path is widely known. That is, the coil spring SP functions as a connection electrode for electrically connecting the ignition coil 270 and the ignition plug 160.

[0005]

However, in the connection structure between the ignition plug 160 and the ignition coil 270 using the above-mentioned conventional coil spring SP, the piston operation in the combustion chamber and the road surface condition (road surface) accompanying the operation of the internal combustion engine are performed. When the internal combustion engine is vibrated due to (irregularities), the contact state between the coil spring SP and the power receiving terminal 180 of the ignition plug 160 may be defective. Here, the direction (vibration mode) of the vibration applied to the ignition coil 270 and the ignition plug 160 due to the vibration of the internal combustion engine is almost the axis of the ignition plug 160 due to the vertical movement of the piston in the combustion chamber. Direction, that is, the same direction as the direction of expansion and contraction (pressure contact) of the coil spring SP pressed against the one end 181 of the power receiving terminal 180.

Therefore, when a high frequency vibration is applied to the internal combustion engine, depending on the spring constant of the coil spring SP, the coil spring SP itself has an inertia caused by vibration applied in the same direction as the expansion and contraction direction of the coil spring SP. You will not be able to withstand power. As a result, a change occurs in the pressing force acting between the coil spring SP and the power receiving terminal 180, causing a change in the contact resistance between the two. As a result, a repeated phenomenon that the coil spring SP separates from the power receiving terminal and comes into contact with the power receiving terminal 180 again occurs. Will happen. Thus, the coil spring SP and the power receiving terminal 18 of the ignition plug 160
If a contact failure of 0 occurs, the ignition coil 27
A change in the resistance value of the conductive path between 0 and the ignition plug 160,
There is a possibility that a fragmentary interruption of the conductive path may occur, preventing normal spark discharge at the spark plug 160 from being generated.

To solve such a problem, it is conceivable to increase the spring constant of the coil spring. However, the frequency range of the vibration of the internal combustion engine is from several hundred [Hz] to several tens [kHz].
z], it is practically very difficult to cancel the effect of the high frequency range vibration of the internal combustion engine by adjusting the spring constant.

The present invention has been made in view of the above problems, and has been made in consideration of a change in a resistance value in a conductive path connecting an ignition plug and an ignition coil and a fragmentary interruption of the conductive path due to the influence of vibration of an internal combustion engine. And to provide an ignition device for an internal combustion engine in which the ignition plug and the ignition coil are connected so that the ignition high voltage generated in the ignition coil can be reliably applied to the power receiving terminal of the ignition plug. With the goal.

[0009]

According to a first aspect of the present invention, there is provided an electro-optical device comprising: a shaft-shaped center electrode inserted at a tip end of a shaft hole of an insulator; A ground electrode coupled to a metal shell provided on the outer periphery of the body, the other end of which is opposed to the center electrode to form a spark discharge gap; A spark plug having a shaft-like power receiving terminal, which is electrically connected, a primary winding and a secondary winding, and a high ignition voltage for generating spark discharge in a spark discharge gap of the spark plug. An ignition device for an internal combustion engine, comprising: an ignition coil generated in a secondary winding; and a connection electrode for electrically connecting one end of a secondary winding to a power receiving terminal. A cylindrical portion formed so as to surround the direction, and the cylindrical portion has a power receiving end. A plurality of elastic portions that can be pressed in the circumferential direction are provided, and the power receiving terminal is inserted into the cylindrical portion of the connection electrode, and the elastic portion presses against the outer peripheral surface of the power receiving terminal, thereby forming the secondary winding. One end and the power receiving terminal are electrically connected.

In the ignition device for an internal combustion engine according to the present invention (claim 1), the power receiving terminal is inserted into the cylindrical portion of the connection electrode, and the plurality of elastic portions formed in the cylindrical portion are formed on the outer periphery of the power receiving terminal. By pressing against the surface, the power receiving terminal of the ignition plug and one end of the secondary winding of the ignition coil are connected via the connection electrode. Note that the connection electrode is electrically connected to one end of the secondary winding.

That is, the connection electrode has a cylindrical portion surrounding the circumferential direction of the power receiving terminal of the ignition plug, and further has a cylindrical portion in the circumferential direction of the power receiving terminal (ie, substantially perpendicular to the axial direction of the spark plug). The connection electrode is compressed in the axial direction of the ignition plug (power receiving terminal), and one end thereof is not in contact with the power receiving terminal. The connection electrode comes into contact with the power receiving terminal in a direction substantially orthogonal to the axial direction of the ignition plug by the elastic portion. As a result, even when the connection electrode is subject to vibration in which the axial direction of the spark plug is vibrated along with the operation of the internal combustion engine, the influence of the vibration does not affect the expansion and contraction (pressure contact) directions of the plurality of elastic portions. In addition, poor contact such as a change in contact resistance between the connection electrode and the power receiving terminal can be suppressed even by the influence of vibration of the internal combustion engine.

Further, by providing a plurality of elastic portions in the tubular portion constituting the connection electrode, the contact area between the connection electrode (elastic portion) and the outer peripheral surface of the power receiving terminal is increased, and the connection between the ignition plug and the ignition coil is made. The contact resistance in the conductive path can be reduced. Further, since the plurality of elastic portions approach the power receiving terminal due to the elastic force, the contact between the power receiving terminal and the connection electrode can be more reliably maintained.

Therefore, according to the ignition device for an internal combustion engine of the present invention (claim 1), poor contact between the connection electrode and the power receiving terminal can be suppressed by the vibration generated by the operation of the internal combustion engine, and the ignition plug and the ignition coil The connection between the ignition plug and the ignition coil can be made such that an increase in the resistance value of the conductive path that connects the power supply and the fragmentary interruption of the conductive path hardly occurs.

The elastic force of each elastic portion provided on the cylindrical portion of the connection electrode may be increased in order to maintain a state of contact with the outer peripheral surface of the power receiving terminal. It becomes difficult to attach / detach. For this reason, it is preferable that the elastic force of each elastic portion be large enough to maintain the contact with the power receiving terminal and to allow the work of attaching and detaching to and from the power receiving terminal, from 3 [N / mm] to 50 [N / mm].

[0015] In the ignition device for an internal combustion engine described above (claim 1), the power receiving terminal may be formed in a substantially circular outer peripheral surface as described in claim 2. That is, the power receiving terminal is formed in a substantially circular shape on the outer peripheral surface, and thus has a cylindrical shape extending in the axial direction of the spark plug. Thus, the elastic portion provided on the cylindrical portion of the connection electrode is pressed against the outer peripheral surface of the power receiving terminal in a direction substantially orthogonal to the axial direction of the spark plug, and the vibration having the axial direction of the spark plug as the vibration direction. Occurs, the contact position with the elastic portion (connection electrode) on the outer peripheral surface of the power receiving terminal may slightly change.
The contact area between the power receiving terminal and the elastic portion (connection electrode) does not change, and the change in the contact resistance between the two can be effectively suppressed.

Some power receiving terminals are formed so that their axial cross-sectional shape (outer peripheral shape) is along the axial cross-sectional shape of the connection electrode. However, such power receiving terminals are subject to individual differences during manufacturing. Due to a dimensional error or a dimensional error in the mounting position, there is a possibility that the power receiving terminal and the connection electrode (elastic portion) do not abut at an appropriate position. On the other hand, the power receiving terminal according to claim 2 has a connection electrode (elastic portion) at the time of mounting even when a dimensional error or the like due to individual differences occurs.
Although the contact position with the connection electrode changes, the contact with the connection electrode can be surely maintained.

Therefore, according to the ignition device for an internal combustion engine of the present invention (claim 2), even when the axial vibration of the spark plug occurs due to the vibration of the internal combustion engine, the poor contact between the connection electrode and the power receiving terminal is prevented. Thus, a conductive path for applying the ignition high voltage generated in the secondary winding to the ignition plug can be secured.

Further, in order to more reliably prevent the connection electrode and the power receiving terminal from separating,
A resin layer having an urging force for urging the connection electrode toward the power receiving terminal may be provided around the cylindrical portion of the connection electrode. By providing such a resin layer, the elastic portion (connection electrode) is urged to the power receiving terminal by the urging force of the resin layer in addition to the elastic force of the elastic portion, and vibration of the internal combustion engine is generated. Even in this case, it is possible to more reliably maintain the pressure contact state of the elastic portion provided on the cylindrical portion of the connection electrode to the outer peripheral surface of the power receiving terminal in a direction substantially orthogonal to the axial direction of the ignition plug. Further, by providing the resin layer, the conductive path, which is a high-voltage path, and the external device can be more reliably insulated.

Further, the power receiving terminal may have a conductive film formed on an outer peripheral surface thereof. That is, the power receiving terminal is exposed to an environment at a high temperature (for example, 800 to 900 [° C.]) in the manufacturing process of the ignition plug, and an insulating oxide film may be formed on a part of the surface. Although the thickness of the conductive oxide film itself varies, a relatively thick (for example, 5 [μm] or more) insulating oxide film is formed on a part of the surface of the power receiving terminal that is in contact with the connection electrode (elastic portion). In such a case, the contact resistance between the connection electrode and the power receiving terminal increases.

Therefore, by applying a conductive film made of a metal having high conductivity (conductivity) such as gold, silver or nickel on the surface of the power receiving terminal, the conductive film contacts the thin portion of the insulating oxide film. Therefore, even if the connection electrode (elastic part) contacts any part of the surface of the power receiving terminal,
It is possible to prevent an increase in the contact resistance of both, and by using the connection electrode of the present invention, even when affected by the vibration of the internal combustion engine, the contact electrode can be satisfactorily changed without changing the value of the contact resistance. Can be maintained.

Next, in the ignition device for an internal combustion engine according to any one of claims 1 to 4, as described in claim 5, the ignition plug and the ignition coil are arranged in the axial direction. It is preferable to make it impossible to rotate. Thereby, the connection state of the connection electrode to the power receiving terminal can be more stably maintained even after the connection between the ignition plug and the ignition coil and the vibration of the internal combustion engine.

Incidentally, a method of detecting an ionic current is known as one method for detecting misfire or knocking of an internal combustion engine, for example, by detecting the ionic current between electrodes of a spark plug (a center electrode and a ground electrode). This is performed by applying a detection voltage having a polarity opposite to that of the ignition high voltage and detecting a current flowing between the electrodes. The application of the detection voltage between the electrodes of the ignition plug is often performed by using a conductive path including the secondary winding of the ignition coil, the connection electrode, and the power receiving terminal of the ignition plug. When the ion current is detected by using the internal combustion engine, if the resistance of the conductive path increases or the conductive path is interrupted due to poor contact between the power receiving terminal and the connection electrode due to the vibration of the internal combustion engine, the ion current must be accurately detected. Can not be done. In particular, since the ionic current is a very small current, a slight change in the resistance value of the conductive path greatly affects the detection accuracy.

Therefore, the ignition device for an internal combustion engine described above (any one of claims 1 to 5) may include an ionic current detecting means. That is, the above (claims 1 to 5)
The ignition device for an internal combustion engine according to any one of the above, can suppress poor contact between the connection electrode and the power receiving terminal due to the vibration generated by the operation of the internal combustion engine, and reduce the resistance value in the conductive path connecting the ignition plug and the ignition coil. The ignition plug and the ignition coil are connected so that the increase and the fragmentary interruption of the conductive path hardly occur. Thereby, it is possible to suppress a decrease in detection accuracy when detecting the ion current.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a connection structure between an ignition coil and an ignition plug in an ignition device 1 for an internal combustion engine according to an embodiment, and a part thereof is shown in a sectional view.

In FIG. 1, the spark plug 11 generates a spark discharge in the spark discharge gap g formed between the center electrode 19 and the ground electrode 21, and the spark plug 11 generates a spark discharge. 3 shows a connection structure of the ignition coil 27 for generating a high voltage for ignition. Hereinafter, the side where the spark discharge gap g is formed in the axial direction of the spark plug 11 is referred to as a front end side (front side), and the opposite side is referred to as a rear end side (rear side).

The ignition unit 41 has a built-in igniter (not shown) and a connector 45, and receives a signal from an external device and outputs a signal to the external device via the connector 45. It is carried out. In addition, a cylinder head 5 is provided in front of the ignition unit 41.
A casing portion 33 made of a substantially cylindrical insulating resin material that can be inserted into the plug hole 53 provided in the housing 1 is integrally provided. A connection electrode 31 that is electrically connected to one end of the secondary winding of the ignition coil 27 is disposed inside the casing 33 on the front side.

An ignition coil 27 is built in the casing 33. Although not shown in detail, the ignition coil 27 is provided with an iron core at a central shaft portion. A secondary winding and a primary winding are coaxially wound therearound. The ignition coil 27 is formed by molding an epoxy resin with one end 27a of the secondary winding being led out. Then, by connecting one end 27a of the secondary winding derived from the ignition coil 27 to the connection portion 31c of the connection electrode 31, the secondary winding and the connection electrode 31 are electrically connected to each other. A conductive path for applying the ignition high voltage generated in the next winding to the ignition plug 11 is formed.

When the primary coil is energized or cut off by an igniter according to an external command, the ignition coil 27 applies a high voltage for ignition to generate spark discharge at the ignition plug 11 to the secondary coil. Occurs at both ends of the line. Here, FIG. 2 is a perspective view showing the connection electrode 31 when the front side portion of the casing portion 33 is enlarged and the inside is seen through. FIG. 4 is a development view of the connection electrode 31 (FIG. 4).
(A)) and a side view (FIG. 4 (b)).

As shown in FIG. 4A, when the cylindrical connection electrode 31 is expanded, the connection electrode 31 becomes a rectangular shape. By providing a plurality of vertically long slits 31b, a plurality of vertically long elastic portions 31a are formed. And one side 31 of the rectangle
f and the elastic portion 3 on the opposite side 31e.
1a is overlapped to form a cylindrical portion (cylindrical portion) 31d as shown in FIG. 4 (b). At this time, the cylindrical portion 31
The inner diameter of d is formed larger than the outer diameter of the power receiving terminal 13 of the ignition plug 11 described later. In addition, the connection electrode 31
A connecting portion 31c to which one end of the secondary winding is joined is integrally provided.

When the cylindrical portion 31d is formed by the connection electrode 31, each of the plurality of elastic portions 31a is connected to the central axis of the cylindrical portion 31d (shown by a dotted line in FIG. 4B).
It is formed in a curved shape so as to have a radial elastic force toward. The elastic force of each elastic portion 31a provided on the cylindrical portion 31d of the connection electrode 31 is applied to a power receiving terminal 1 described later.
3 can be reliably maintained in contact with the outer peripheral surface,
Also, in order to be able to attach / detach to / from the power receiving terminal 13,
It is set in the range of 3 [N / mm] to 50 [N / mm].

Also, as shown in FIG.
Are a shaft-shaped center electrode 19 inserted at the end of the shaft hole of the insulator 15 and the metal shell 1 provided on the outer periphery of the insulator 15.
7, the other end of which is bent back to the side, the side of which is opposed to the tip of the center electrode 19 to form a spark discharge gap g; And a power receiving terminal 13 electrically connected to the center electrode 19. And the power receiving terminal 13
The outer peripheral surface is formed in a substantially circular shaft shape, and the surface thereof is plated with gold.

Then, as shown in FIG.
Is inserted from the front side of the casing 33 and inserted and arranged in the cylindrical portion 31d of the connection electrode 31,
The power receiving terminal 13 of the ignition plug 11 comes into contact with the connection electrode 31, and the power receiving terminal 13 of the ignition plug 11 and one end 27a of the secondary winding of the ignition coil 27 are electrically connected. At this time, each of the plurality of elastic portions 31a provided on the cylindrical portion 31d of the connection electrode 31 comes into pressure contact with the outer peripheral surface of the power receiving terminal 13 in a direction substantially orthogonal to the axial direction of the ignition plug.

In this embodiment, when the power receiving terminal 13 of the ignition plug 11 is actually connected to the connection electrode 31, a substantially cylindrical resin layer 35 made of silicon rubber is used as shown in FIG. However, the illustration of the resin layer 35 is omitted in FIG. A connection procedure for connecting the power receiving terminal 13 of the ignition plug 11 to the connection electrode 31 and a procedure for mounting the ignition device 1 for an internal combustion engine of the present embodiment to the internal combustion engine will be described below.

First, the spark plug 11 is inserted into a plug hole 53 provided in a cylinder head 51 of an internal combustion engine. The ignition plug 11 is rotated by applying a tightening tool such as a plug wrench to a hexagonal portion 17 a formed on the metal shell 17. Attach to the institution.

On the other hand, a resin layer 35 is mounted on the tip side of a casing portion 33 having a built-in connection electrode 31 connected to one end of the ignition coil 27 and a secondary winding of the ignition coil 27, and a base of the casing portion 33. Grommets 43 for preventing water droplets from entering the plug holes 53
Attach. At this time, the output terminal contact portion 35b formed on the inner surface on the rear side of the resin layer 35 is
The resin layer 35 and the casing part 33 are mounted in a state in which the resin layer 3 is sandwiched.

Then, the resin layer 35 and the grommet 43
Is inserted into the plug hole 53, and the resin layer 35 is mounted on the ignition plug 11 so that the resin layer 35 covers the insulator 15 from the rear end of the hexagonal portion 17a to the power receiving terminal 13. . An insulator contact portion 35a having an elastic force for sandwiching the insulator 15 is formed on the inner surface of the resin layer 35 so as not to fall off from the ignition plug 11.

Thus, the spark plug 11 and the casing 33 are mounted, and at this time, the power receiving terminal 13 of the spark plug 11 and the connection electrode 31 (elastic portion 31a) come into contact. Then, the power receiving terminal 13 of the ignition plug 11 and one end 27a of the secondary winding of the ignition coil 27 are electrically connected, and the ignition high voltage generated in the secondary winding of the ignition coil 27 is ignited. A conductive path for applying to the plug 11 is formed.

As described above, the ignition plug 11 and the ignition coil 27 in the ignition device for an internal combustion engine of this embodiment are described.
According to the connection structure, the connection electrode 31 is connected to the ignition plug 1.
The power receiving terminal 13 includes a cylindrical portion 31d surrounding the circumferential direction of the power receiving terminal 13, and the cylindrical portion 31d can be pressed in the circumferential direction of the power receiving terminal 13 (that is, a direction substantially orthogonal to the axial direction of the ignition plug 11). Since the elastic portion 31a is provided, the connection electrode 31 is moved relative to the power receiving terminal 13 by the elastic portion 31a.
It takes a form that makes contact in a direction substantially perpendicular to the axial direction of the spark plug 11. For this reason, even when vibration occurs in the axial direction of the spark plug 11 due to the vibration of the internal combustion engine, the vibration exerts an influence on the expansion and contraction (pressure contact) direction of the plurality of elastic portions 31a. Although the contact position of the connection electrode 31 on the outer peripheral surface of the power receiving terminal 13 changes, contact failure such as a change in contact resistance between the power receiving terminal 13 and the connection electrode 31 can be suppressed, and the secondary winding of the ignition coil 27 can be suppressed. Can be reliably applied to the ignition plug 11.

When vibration occurs in a direction perpendicular to the longitudinal direction of the ignition plug 11, one of the plurality of elastic portions 31 a having a radial elastic force toward the central axis is applied to the power receiving terminal 13. As a result, the electrical connection between one end of the secondary winding and the power receiving terminal can be maintained, and a conductive path can be secured.

Further, the cylindrical portion 3 forming the connection electrode 31
Since the plurality of elastic portions 31a are provided in 1d, the connection electrode 3
1 (the elastic portion 31a) and the outer peripheral surface of the power receiving terminal 13 have a large contact area, and the resistance value of the conductive path connecting the ignition plug 11 and the ignition coil 27 can be reduced. Further, since the plurality of elastic portions 31a are arranged concentrically in the cylindrical portion 31d and abut against the power receiving terminal 13 by the elastic force of the elastic portion 31a, the contact between the power receiving terminal 13 and the connection electrode 31 is more reliably performed. Can be maintained.

Next, as a second embodiment, a connection structure between an ignition plug and an ignition coil in an ignition device for an internal combustion engine in which the ignition plug and the ignition coil are not rotatable in the axial direction will be described. FIG. 3 is a configuration diagram of the ignition device 3 for an internal combustion engine according to the second embodiment, a part of which is shown as a cross-sectional view.

As shown in FIG. 3, an ignition device 3 for an internal combustion engine
Is a spark plug 1 that generates a spark discharge in a spark discharge gap g formed between the center electrode 19 and the ground electrode 21.
1, an ignition coil 27 for generating a high voltage for ignition for generating spark discharge in the ignition plug 11, a casing 33 having the ignition coil 27 therein, and a substantially cylindrical resin layer 35 made of silicon rubber. And a substantially cylindrical housing 37 having an ignition coil 27 and a casing portion 33 therein, and a tip portion formed so as to be fitted to the hexagonal portion 17a of the ignition plug 11; An ignition unit 41 having a built-in igniter that receives a signal and outputs a signal to an external device, and controls energization and cutoff of the ignition coil 27 in accordance with an external command is provided. Ignition coil 27
Are not rotatable in the axial direction.

The ignition plug 11, the ignition coil 27,
The resin layer 35 and the connection electrode 31 are respectively formed by the ignition plug 11 and the
It has the same configuration as the ignition coil 27, the resin layer 35, and the connection electrode 31. The same components as those in the first embodiment are denoted by the same reference numerals.

The power receiving terminal 13 of the ignition plug 11
When the connection electrode 31 and the connection electrode 31 are connected, the rear side of the power receiving terminal 13 is inserted from the front side of the casing 33 as shown in FIG. Insert and arrange in the cylindrical part 31d. At this time, as in the first embodiment, each of the plurality of elastic portions 31a provided on the cylindrical portion 31d of the connection electrode 31 is oriented substantially orthogonal to the axial direction of the ignition plug with respect to the outer peripheral surface of the power receiving terminal 13. Is brought into pressure contact with.

In the second embodiment, the casing 33 is formed separately from the ignition unit 41.
The casing 33, the ignition coil 27, and the connection electrode 31 are provided inside the housing 37. Although not shown, the ignition unit 41 is provided with a terminal having the same shape as the above-described power receiving terminal 13, and an electrode having the same shape as the above-described connection electrode 31 is provided on the rear side of the casing 33. The ignition unit 41 and the casing 33 are provided.
Are connected, the terminal and the electrode are electrically connected.

Further, the housing 37 is made of a ferromagnetic material, and the front end portion 37a is formed in a shape (having a hexagonal cross section) that can be fitted to the hexagonal portion 17a of the spark plug 11, and the rear end portion 3a is formed.
7b is formed in a shape (having a hexagonal cross section) that can be fitted with a tightening tool (such as a wrench). The housing 37 thus configured plays a role similar to that of a tightening tool such as a plug wrench when the ignition plug 11 is mounted on the internal combustion engine. The method of mounting the spark plug 11 on the internal combustion engine will be described later.

Here, a procedure for assembling the ignition device 3 for an internal combustion engine of the second embodiment using the above-described components,
And a procedure for mounting the engine on an internal combustion engine will be described. First,
A resin layer 35 is fitted to the front end side of a casing 33 having a built-in connection electrode 31 connected to one end of an ignition coil 27 and a secondary winding of the ignition coil 27.
And the resin layer 35 are connected.

On the other hand, the spark plug 11 is inserted into the housing 37 from the opening on the side of the front end portion 37a, and the hexagonal portion 17a of the metal shell 17 of the spark plug 11 and the front end portion 37a of the housing 37 are fitted. Thereafter, at least one of the side surfaces of the front end portion 37a of the housing 37 is crimped inward to form an inward projection on the side surface, so that the housing 37 and the ignition plug 11 (specifically, the hexagonal portion 17a) are connected. It is configured so that it cannot rotate in the axial direction.

Subsequently, the connected casing portion 33 and resin layer 35 are inserted into the inside of the housing 37 from the opening on the rear end portion 37b side, and the resin layer 35 is inserted into the hexagonal portion 17a of the metal shell 17 of the ignition plug 11. To cover the insulator 15 from the rear end to the power receiving terminal 13.
The casing 33 is arranged inside the housing 37 while the resin layer 35 is mounted on the housing 37.

At this time, similarly to the first embodiment, the power receiving terminal 13 of the ignition plug 11 is inserted into the cylindrical portion 31d of the connection electrode 31, and the plurality of elastic portions 31a formed on the cylindrical portion 31d receive the power. The outer peripheral surface of the terminal 13 has a spark plug 11
The connection electrode 31 and the power receiving terminal 13 are connected by pressure contact in a direction substantially orthogonal to the axial direction of the connection electrode 31. Thus, the power receiving terminal 13 of the ignition plug 11 and the ignition coil 27
Is electrically connected to one end of the secondary winding of the ignition coil 2.
High voltage for ignition generated in the secondary winding of the ignition plug 11
Is formed.

Thus, the casing 33 (the ignition coil 27), the resin layer 35, the housing 37 and the ignition plug 11 are combined in an integrated state to form an assembly.
Then, the rear end portion 37b of the housing 37 in the assembly
The assembly is inserted into the plug hole 53 while a tightening tool (such as a wrench) is fitted in the plug hole 53. Then, by rotating the assembly with a tightening tool, a screwing groove 17 provided on the outer periphery of the metal shell 17 of the ignition plug 11 is formed.
By b, the assembly is mounted on the internal combustion engine.

The grommet 43 for preventing intrusion of water droplets and the like into the plug hole 53 and the ignition unit 41 for transmitting and receiving signals to and from the outside are mounted after the assembly is mounted on the internal combustion engine. Engine ignition device 3
Is completed. Next, as a third embodiment, in the assembly to which the connection structure between the ignition plug and the ignition coil of the present invention is applied, the ignition plug is not provided with a screw groove (screw groove), and The case where the ignition plug and the ignition plug are integrated so as not to rotate will be described.

FIG. 5 is a configuration diagram of an ignition device 5 for an internal combustion engine according to a third embodiment, a part of which is shown in a sectional view. As shown in FIG. 5, the ignition device 5 for an internal combustion engine
A spark plug 11 that generates a spark discharge in a spark discharge gap g formed between the electrode 9 and the ground electrode 21, and an ignition coil 27 that generates a high ignition voltage for generating a spark discharge in the spark plug 11 A casing portion 33 made of an insulating resin material having an ignition coil 27 therein, a substantially cylindrical resin layer 35 made of silicone rubber, an ignition coil 27 and a casing portion 33 inside, and a tip portion 37a having A substantially cylindrical housing 37 formed so as to be fittable with the hexagonal portion 17a of the ignition plug 11;
An ignition unit 41 that receives a signal from an external device and outputs a signal to the external device via the control unit 5, and controls the energization and cutoff of the ignition coil 27 according to an external command.
And

The ignition coil 27, the resin layer 35, the casing 33, the ignition unit 41, and the connection electrode 31 are respectively composed of the ignition coil 27, the resin layer 35, the casing 33, and the ignition unit shown in the first embodiment. 41, the same configuration as the connection electrode 31. The same components as those in the first embodiment are denoted by the same reference numerals. The ignition unit 41 shown in FIG. 5 is different from the ignition unit 41 shown in FIG. 1 in the outer shape, but the operation is the same.

The ignition device 5 for an internal combustion engine according to the third embodiment
Is similar to that of the second embodiment. When the power receiving terminal 13 of the ignition plug 11 is connected to the connection electrode 31, as shown in FIG. 2, the rear side of the power receiving terminal 13 is connected to the front side of the casing 33 as in the first embodiment. And the cylindrical portion 31 of the connection electrode 31
Insert and place in d. At this time, as in the first embodiment, each of the plurality of elastic portions 31a provided on the cylindrical portion 31d of the connection electrode 31 is oriented substantially orthogonal to the axial direction of the ignition plug with respect to the outer peripheral surface of the power receiving terminal 13. Is brought into pressure contact with.

Here, a procedure for assembling the ignition device 5 for an internal combustion engine of the third embodiment and a procedure for mounting the same to the internal combustion engine will be described. First, the ignition coil 27 and the connection electrode 31 connected to one end of the secondary winding of the ignition coil 27
Is connected to the resin layer 35 and the distal end side of the casing 33 in which is embedded. In this embodiment, the casing 33 and the ignition unit 41 are integrally formed in advance.

On the other hand, the ignition plug 11 is inserted into the inside of the housing 37 from the opening on the side of the distal end portion 37a, and the hexagonal portion 17a of the metal shell 17 of the ignition plug 11 and the distal end portion 37a of the housing 37 are fitted. Thereafter, at least one side surface of the front end portion 37a of the housing 37 is swaged inward to form an inward projection on the side surface, so that the housing 37 and the ignition plug 11 (specifically, the hexagonal portion 17a) are connected. It is configured so that it cannot rotate in the axial direction.

Subsequently, the connected casing portion 33 (including the ignition unit 41) and the resin layer 35 are removed from the rear end portion 37.
The spark plug 11 is inserted into the housing 37 through the opening on the side b so that the resin layer 35 covers the insulator 15 from the rear end of the hexagonal portion 17 a of the metal shell 17 of the spark plug 11 to the power receiving terminal 13. The casing 33 is arranged inside the housing 37 while the resin layer 35 is mounted on the housing 37. At this time, similarly to the first embodiment, the power receiving terminal 13 of the ignition plug 11 is inserted into the cylindrical portion 31d of the connection electrode 31, and the plurality of elastic portions 31 formed on the cylindrical portion 31d are formed.
a is pressed against the outer peripheral surface of the power receiving terminal 13 in a direction substantially orthogonal to the axial direction of the ignition plug 11 so that the connection electrode 3
1 and the power receiving terminal 13 are connected. In this manner, the power receiving terminal 13 of the ignition plug 11 and one end of the secondary winding of the ignition coil 27 are electrically connected, and the ignition high voltage generated in the secondary winding of the ignition coil 27 is applied to the ignition plug. 11 is formed.

Here, the ignition plug 11 of the third embodiment is
Of the metal shell 17, a screw groove (the screw groove in the second embodiment) is provided on the outer periphery of a tip portion 17d located further forward than the largest diameter portion 17c located on the front side of the hexagonal portion 17a. 17b) is not provided and the outer peripheral surface has a substantially cylindrical shape. In the plug hole 53 of the cylinder head 51 in which the spark plug 11 is mounted, a portion in which the tip of the metal shell 17 is located is not formed with a screwing groove. Plug hole 53
Can be inserted in a loose fit.

Further, in the ignition device 5 for an internal combustion engine according to the third embodiment, a predetermined portion on the outer peripheral surface of the housing 37 is provided.
A flange portion 39 that can be detachably attached to the cylinder head 51 is formed. Here, in order to explain the flange portion 39 in detail, FIG. 6 is an enlarged perspective view centered on the flange portion 39. As shown in FIG. 6, a plurality of (three in the third embodiment) flange portions 39 are provided at equal intervals from the outer peripheral surface of the housing 37 so as to protrude outward in the radial direction. Here, the flange portion 39 has a first plate surface 39a and a second plate surface 39b, which are integrally connected.

The first plate surface 39a is a portion to be fitted to a plurality (three in the third embodiment) of mounting portions 55 provided in the cylinder head 51 in advance and having a substantially L-shaped cross section. . Also, the second plate surface 39b is connected to the first plate surface 39a.
, And when the first plate surface 39a is fitted to the mounting portion 55 of the cylinder head 51, the cylinder head 51 comes into contact with the mounting portion 55 to restrict the movement of the first plate surface 39a. Fulfill.

Further, of the first plate surface 39a, the second plate surface 3
The plate surface 39c occupying substantially half of the side on which the 9b is erected is configured to slightly warp upward in the drawing at a boundary portion occupying the other approximately half, and the first plate surface 39a is formed of a cylinder head. When or after fitting to the mounting portion 55 of the 51, it functions as an elastic portion that exerts a pressing action on the cylinder head 51. The elastic portion (plate surface 39c) allows the ignition device 5 for the internal combustion engine to move in the direction of the combustion chamber 57 (FIG. 5).
(In other words, it is urged toward the axially forward side of the spark plug).

Next, a procedure for mounting the ignition device 5 for an internal combustion engine of the third embodiment on the cylinder head 51 will be described. First, in the plug hole 53 of the cylinder head 51,
The ignition device 5 for an internal combustion engine assembled according to the above-described procedure is inserted from the side of the ignition plug 11. At this time, the ignition device 5 for the internal combustion engine is loosely inserted into the plug hole 53 because no screw groove is formed at the tip end 17 d of the metal shell 17 of the ignition plug 11. Then, after the internal combustion engine ignition device 5 is inserted until the first plate surface 39a of the flange portion 39 formed on the housing 37 abuts against one end surface of the cylinder head 51, the internal combustion engine ignition center is set around the axial direction of the ignition plug. The ignition device 5 is rotated until the second plate surface 39b comes into contact with the mounting portion 55, and the flange portion 39 and the mounting portion 55 are fitted.

At this time, the ignition device 5 for the internal combustion engine uses the elastic portion (plate surface 39c) which is a part of the first plate surface 39a forming the flange portion 39 (see FIG. 6) to move in the direction of the combustion chamber 57 (see FIG. 6). For example, on the front side in the axial direction of the spark plug)
It is adjusted so as to be urged with a force of [N / mm ² ]. Thus, the ignition device 5 for the internal combustion engine is mounted on the cylinder head 51.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various embodiments can be adopted. For example, in each of the embodiments described above, an ion current detection circuit can be provided inside the ignition unit 41. Here, FIG. 7 shows an example of an electric circuit diagram of an ignition device for an internal combustion engine provided with an ion current detection circuit (ion current detection unit). As the ignition device for the internal combustion engine, the one described in the third embodiment is used.

As shown in FIG. 7, an ignition device 5 for an internal combustion engine is provided.
Means that electric energy (for example, voltage 12V) is applied to the primary winding L1.
DC power supply (battery) 111 for supplying power, an ignition coil 27 having a primary winding L1 and a secondary winding L2, and an npn as an igniter connected in series with the primary winding L1
Main Control Transistor 115 composed of Transistor Type Transistor
And a spark plug 11 that forms a closed loop with the secondary winding L2 to generate a spark discharge between the center electrode 19 and the ground electrode 21, and is provided on a closed loop including the secondary winding L2 and the spark plug 11. An ion current detection circuit 129 that outputs a first detection voltage Vio proportional to the magnitude of the ion current; and an ion current that outputs an ion current signal Sio based on the first detection voltage Vio output from the ion current detection circuit 129. A conversion circuit 141 and a main control transistor 115 for generating spark discharge in the spark plug 11
An electronic control unit (hereinafter referred to as an ECU) for controlling the internal combustion engine to which an ignition command signal IG is output based on the operating state of the internal combustion engine, and to which an ion current signal Sio from the ion current conversion circuit 141 is input. ) 121.

Then, the ECU 121 controls the drive of the main control transistor 115 to supply current to the primary winding L1.
By performing the cutoff, a high voltage for ignition is generated at both ends of the secondary winding L2, and a spark discharge is generated between the electrodes 19-21 of the ignition plug 11. Next, the ion current detection circuit 129
Is an ion current detection resistor 131 having one end grounded, a capacitor 135 connected in series to an end of the ion current detection resistor 131 opposite to the ground side, a cathode grounded, and an anode connected to the ion current detection resistor 131. A diode 133 connected to a connection point between the resistor 131 and the capacitor 135 and connected in parallel to the ion current detection resistor 131;
The cathode 135 is connected to the end of the capacitor 135 on the side opposite to the side connected to the ion current detection resistor 131, and has a Zener diode 137 whose anode is grounded. In the ion current detection circuit 129 thus configured, the connection point between the capacitor 135 and the Zener diode 137 is connected to the secondary winding L2, and the connection point between the ion current detection resistor 131 and the capacitor 135 is connected to the ion current. It is connected to the conversion circuit 141.

Then, in the ion current detection circuit 129,
Immediately after the spark discharge occurs, the secondary current i2 (discharge current) flowing from the secondary winding L2 is
5, flows through a path passing through the diode 133;
Thereafter, the high voltage for ignition in the secondary winding L2 decreases and the spark discharge ends, and the secondary current i2 due to the high voltage for ignition is reduced.
Is stopped flowing, the charged capacitor 135 is discharged, so that the capacitor 135, the secondary winding L2, the spark plug 11, and the ion current detection resistor 131 are turned on in this order.
o flows. At this time, since the voltage across the ion current detection resistor 131 is proportional to the magnitude of the ion current Iio, the first detection voltage Vio indicates a value proportional to the ion current Iio, and the ion current conversion circuit 141 An ion current signal Sio is output to the ECU 121 based on the detection voltage Vio. It should be noted that the ECU 121 is provided with the ion current signal Si.
By performing the analysis processing of o, for example, misfire determination, knock determination, and the like are performed.

The ECU 121 comprehensively controls the ignition timing, fuel supply amount, and the like of the internal combustion engine based on the results of these determinations. As described above, when the ion current is detected, the change in the resistance value in the conductive path connecting the secondary winding L2 and the ignition plug 11 greatly affects the detection accuracy. By using the connection structure, a change in the resistance value of the conductive path can be suppressed, and the detection accuracy of the ion current can be improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various embodiments can be adopted. For example, in the above-described embodiment, the ignition coil 27 is disposed inside the casing 33, but the ignition coil may be incorporated in the ignition unit 41.

In other words, when the ignition coil is arranged inside the casing 33, the arrangement space is limited by the size of the plug hole, so that the usable coil is limited, but the ignition coil is built in the ignition unit. In this case, the size restriction is relaxed, and it is possible to use an ignition coil having a relatively large shape.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an ignition device for an internal combustion engine according to a first embodiment.

FIG. 2 is an enlarged perspective view of a connection structure between a connection electrode electrically connected to one end of a secondary winding of an ignition coil and a power receiving terminal of an ignition plug.

FIG. 3 is a configuration diagram of an internal combustion engine ignition device according to a second embodiment.

4A is a development view of a connection electrode, and FIG. 4B is a side view of the connection electrode in a cylindrical shape.

FIG. 5 is a configuration diagram of an internal combustion engine ignition device according to a third embodiment.

FIG. 6 is an enlarged perspective view centering on a flange portion formed on a housing constituting an ignition device for an internal combustion engine according to a third embodiment.

FIG. 7 is an electric circuit diagram of an ignition device for an internal combustion engine provided with an ion current detection circuit.

FIG. 8 is a configuration diagram showing a conventional connection structure between an ignition coil and an ignition plug.

[Explanation of symbols]

1, 3, 5: ignition device for internal combustion engine, 11: ignition plug,
13: power receiving terminal, 15: insulator, 17: metal shell, 19
... Center electrode, 21 ... Ground electrode, 27 ... Ignition coil, 31
... Connection electrode, 31a elastic part, 31d cylindrical part (cylindrical part), 33 casing part, 35 resin layer, 37 housing, 129 ion current detection circuit.

Claims (5)

[Claims] 1. An axial center electrode inserted into the distal end of a shaft hole of an insulator, one end of which is coupled to a metal shell provided on the outer periphery of the insulator, and the other end facing the center electrode. A spark plug including a ground electrode that forms a spark discharge gap and a shaft-shaped power receiving terminal that is inserted into the rear end side of the shaft hole of the insulator and is electrically connected to the center electrode; An ignition coil that includes a winding and a secondary winding, and generates an ignition high voltage for generating a spark discharge in the spark discharge gap of the spark plug in the secondary winding. An ignition device for an internal combustion engine, comprising: a connection electrode for electrically connecting one end and the power receiving terminal, wherein the connection electrode is formed in a cylindrical shape so as to surround a circumferential direction of the power reception terminal. The cylindrical portion is pressable in the circumferential direction of the power receiving terminal. A plurality of elastic portions are provided, and the power receiving terminal is inserted into a cylindrical portion of the connection electrode, and the elastic portion is pressed against an outer peripheral surface of the power receiving terminal, so that one end of the secondary winding is connected to the power receiving terminal. An ignition device for an internal combustion engine, wherein the terminal is electrically connected to the terminal. 2. The ignition device for an internal combustion engine according to claim 1, wherein the power receiving terminal is formed in a substantially circular outer peripheral surface. 3. A resin layer having a biasing force for biasing the connection electrode toward the power receiving terminal is provided around a cylindrical portion of the connection electrode. 3. The ignition device for an internal combustion engine according to 2. 4. The ignition device for an internal combustion engine according to claim 1, wherein a conductive film is formed on an outer peripheral surface of the power receiving terminal. 5. The ignition plug and the ignition coil,
The ignition device for an internal combustion engine according to any one of claims 1 to 4, wherein the ignition device is configured so as not to rotate in the axial direction.