JP2003293924A - Ignition device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of component items, a diameter of an ignition device for an internal combustion engine, and cost, in the ignition device where an ignition plug 2 and ignition coil 3 are integrally mounted to a cylinder head. <P>SOLUTION: The ignition device has a cylindrical case 1 where a part for storing components of the ignition plug 2 and a part for storing components of the ignition coil 3 are integrally formed, and the case 1 is made of magnetic and conductive metal material. The case 1 including the part for storing components of the ignition coil is integrally formed of the metal material, so that the case 1 itself has a function of the outer peripheral core of the ignition coil. Therefore, the number of component items, the diameter of the ignition device, and the cost are reduced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine ignition device in which an ignition plug and an ignition coil are integrated.

[0002]

2. Description of the Related Art Conventionally, various ignition devices for internal combustion engines in which an ignition coil and an ignition plug are integrated have been proposed (Japanese Unexamined Patent Application Publication No. 2-212058).
000-252040, European Patent Application Publication No. 09
07019). Further, an internal combustion engine ignition device in which an ignition coil and an ignition plug are integrated with a pressure detection element for detecting a pressure in a combustion chamber is also disclosed.
No. 0-277232.

In this kind of ignition device, generally, ignition coil components such as a primary winding, a secondary winding, a central core and an outer peripheral core are housed in a resin case for the ignition coil, Further, the spark plug components such as the insulator and the center electrode are housed in a metal case for the spark plug.

[0004]

However, since the case for accommodating the ignition coil components is made of resin as described above, the magnetic path of the magnetic flux generated by energizing the primary winding of the ignition coil is A peripheral core was required to construct.

The present invention has been made in view of the above points, and in an internal combustion engine ignition device in which an ignition plug and an ignition coil are integrated and mounted on a cylinder head, an outer peripheral core is unnecessary and the number of parts is reduced. The purpose is to reduce the diameter of the ignition device and to reduce the cost.

[0006]

In order to achieve the above object, in the invention described in claim 1, the central electrode (22) is built in the cylindrical insulator (5), and the discharge is generated in the combustion chamber of the internal combustion engine. An ignition plug (2) for performing, and an ignition coil (3) having a primary winding (31) and a secondary winding (32) for supplying a high voltage to the ignition plug (2) are provided. In an ignition device for an internal combustion engine in which (2) and an ignition coil (3) are mounted on a cylinder head of an internal combustion engine, a portion in which a component of an ignition plug (2) is stored and a component in an ignition coil (3) are stored. A cylindrical case (1) integrally formed with a portion to be formed is provided, and the case (1) is formed of a magnetic material and a conductive metal material.

According to this, since the case itself can be provided with the function of the outer peripheral core of the ignition coil, it is not necessary to separately provide an outer peripheral core as in the conventional case. Therefore, the diameter of the ignition device can be reduced and the cost can be reduced. Is possible.

Further, since the case including the portion for accommodating the ignition coil constituent parts is integrally formed of a metal material, the ignition coil constituent parts are better than those in which the ignition coil constituent parts are accommodated in the resin case. The heat dissipation property of can be improved.

In the invention according to claim 2, the ignition coil (3) is provided with a rod-shaped central core (33), and the case (1).
A slit (15) extending in the axial direction of the central core (33) is formed in a portion surrounding the central core (33) in the above.

According to this, it is possible to prevent the loss due to the annular current generated by the change in the magnetic flux.

According to the invention of claim 3, the case (1)
Is electrically connected to the cylinder head.

With this configuration, the ignition coil portion is covered by the metal case grounded to the cylinder head, so that the ignition noise generated in the ignition coil is shielded by the case and hardly leaks to the outside.

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the specific means described in the embodiments described later.

[0014]

1 to 3 show an embodiment of an ignition device for an internal combustion engine according to the present invention. FIG. 1 is a sectional view showing the overall construction of the ignition device, and FIG. 2 is an illustration of the ignition device. FIG. 3 is an external perspective view showing the whole, and FIG. 3 is a sectional view of a main part of the ignition device showing a flow of magnetic flux generated by energizing the primary winding.

1 to 3, the ignition device has a cylindrical case 1 in which a spark plug 2, an ignition coil 3 and a pressure detecting element 4 are housed, and both electrodes (details of which will be described later) of the spark plug 2 are shown. It is mounted in the plug hole of the cylinder head so as to be exposed in the combustion chamber of the internal combustion engine for a vehicle.

The case 1 is made of a magnetic and conductive metal material, more specifically, a steel material such as S35C material which is carbon steel. The case 1 has an external thread portion 11 on the combustion chamber side on the outer peripheral surface thereof. While being formed, a tightening nut portion 12 is formed on the side opposite to the combustion chamber, and the case 1 is rotated by using the nut portion 12 to screw the male screw portion 11 to a female screw portion (not shown) of the cylinder head. Thus, the ignition device is fixed to the cylinder head.

In the case 1, a cylindrical insulator 5 made of a highly heat-resistant electric insulating material such as ceramic is housed.
The insulator 5 includes a plug-side tube portion 51 located on the combustion chamber side.
And a coil side tubular portion 52 extending from the plug side tubular portion 51 toward the side opposite to the combustion chamber.

On the inner peripheral surface of the case 1, a stepped receiving surface 13 is formed near the combustion chamber side, while on the other hand, on the outer peripheral surface of the plug side cylindrical portion 51 of the insulator 5, the receiving surface 13 is formed. Is formed with a stepped contact surface 53 that abuts against. Then, by the contact between the receiving surface 13 and the contact surface 53,
The case 1 and the insulator 5 are axially positioned and the leakage of combustion gas from between the case 1 and the insulator 5 is prevented. A washer made of an elastic material may be inserted between the receiving surface 13 and the contact surface 53 in order to improve the sealing property.

The spark plug 2 comprises a stem 21 made of a conductive metal, a center electrode 22 made of a conductive metal, a ground electrode 23 made of a conductive metal, and the like. The stem 21 and the center electrode 22 are inserted into the center hole of the plug-side tube portion 51 of the insulator 5, and one end of the center electrode 22 is exposed to the combustion chamber. The ground electrode 23 is integrated with the case 1 by welding or the like,
The ground electrode 23 faces one end of the center electrode 22.

The ignition coil 3 includes a primary winding 31, a secondary winding 32, a cylindrical central core 33 made of a magnetic material, and a secondary spool formed of an electrically insulating resin in a bottomed cylindrical shape. It is composed of 34 and the like.

The primary winding 31 is wound directly on the recess 54 on the outer peripheral surface of the coil side tubular portion 52 of the insulator 5. Both ends of the primary winding 31 are connected to the connector terminals 61 of the connection connector 6 via terminals (not shown) so that a control signal from an igniter (not shown) is input to the primary winding 31. It has become.

Here, in the case 1, the portion surrounding the central core 33 has the function of an outer peripheral core through which magnetic flux flows, and as shown in FIG. 3, the magnetic flux 100 generated in the primary winding 31 is at the center. It flows into the core 33 and the case 1.

A slit 15 extending in the axial direction of the central core 33 is formed in a portion surrounding the central core 33 in the case 1 in order to prevent loss due to an annular current generated by a change in magnetic flux (see FIGS. 2 and 3). Are formed.

The length of the slit 15 is longer than the length of the central core 33. Further, the combustion chamber side end portion 15 a of the slit 15 corresponds to the combustion chamber side end portion 33 a of the central core 33.
To the combustion chamber side, the anti-combustion chamber side end portion 15b of the slit 15 extends to the anti-combustion chamber side from the anti-combustion chamber side end portion 33b of the central core 33. The width of the slit 15 is preferably as narrow as possible in terms of processing.

The secondary spool 34 has a winding cylinder portion 34a around which the secondary winding 32 is wound, and a protruding cylinder portion 34b protruding from the winding cylinder portion 34a toward the side opposite to the combustion chamber. There is. Then, the secondary winding 32 is wound around the outer periphery of the winding cylinder portion 34 a, and the central core 3 is inserted in the central hole of the secondary spool 34.
3 is inserted. After inserting the central core 33, the core holding lid 35 made of an elastic material such as rubber or sponge is inserted into the opening of the central hole of the secondary spool 34, thereby closing the central hole of the secondary spool 34. There is.

The high voltage end of the secondary winding 32 is connected to the spark plug 2
It is electrically connected to the center electrode 22 via the stem 21 of the. On the other hand, the low-voltage end of the secondary winding 32 is electrically connected to the case 1 through the components arranged in the case 1, that is, the first terminal 36, the ground plate 9, and the bolt 8, and , And is electrically connected to the ground electrode 23 via the case 1. In other words, the low voltage end of the secondary winding 32 is electrically connected to the ground electrode 23 without going through the internal combustion engine. Further, it is grounded by contacting the cylinder head via the male screw 11.

The pressure detecting element 4 is one whose potential changes with a change in load applied to it, and is made of lead titanate, for example, and is formed in a thin plate ring shape. And
The pressure detection element 4 is arranged at the end of the coil side tubular portion 52,
One end of the pressure detection element 4 is electrically connected to the cylinder head via the ground plate 9, the bolt 8 and the case 1.

Further, the pressure detecting element 4 and the coil side tubular portion 52
A combustion pressure signal terminal 7 formed of a conductive metal in the shape of a thin plate is arranged between the end and the end. A connector terminal 61 is formed integrally with the combustion pressure signal terminal 7. As a result, the output signal of the pressure detection element 4 is output to a control device (not shown).

The pressure detecting element 4 is connected to the coil side tubular portion 52.
In order to be able to arrange the coil side tubular portion 52, the end portion of the coil side tubular portion 52 is extended to an upper portion in the paper surface of FIG. 1 than the primary winding 31 and the secondary winding 32. In other words, the end portion of the coil side tubular portion 52 projects more toward the side opposite to the combustion chamber than the primary winding 31 and the secondary winding 32.

The bolt 8 is formed of a conductive metal in a cylindrical shape, and the bolt 8 is screwed to the female screw portion 14 formed on the side opposite to the combustion chamber of the case 1, whereby the earth plate 9 and the pressure detecting element 4 are connected. And terminal 7 for combustion pressure signal
Is held between the end of the coil side tubular portion 52 and the bolt 8.

Then, by tightening the bolt 8, a compressive preload is applied to the pressure detecting element 4, and at the contact portion between the receiving surface 13 of the case 1 and the contact surface 53 of the insulator 5, the case 1 and the insulator 5 are connected. It is designed to prevent the leakage of combustion gas from between.

After the bolt 8 is screwed to the female screw portion 14, the resin case 62 of the connector 6 is inserted into the hollow hole of the bolt 8.

In the ignition device having the above structure, the ignition coil 3 generates a high voltage based on the control signal from the igniter, and the spark plug 2 discharges the high voltage in the spark gap to ignite the air-fuel mixture in the combustion chamber. Let Further, the pressure generated by the combustion in the combustion chamber is transmitted to the pressure detecting element 4 via the insulator 5, whereby the pressure detecting element 4 receives a compressive load. Then, the pressure detection element 4 outputs an output signal of a voltage corresponding to the load.

In the present embodiment, the low voltage side of the secondary winding 32 and the ground electrode 23 of the spark plug 2 are electrically connected via the case 1, so that the low voltage side of the secondary winding 32 is connected to the internal combustion engine. A connector terminal and a wire harness for electrically connecting to the engine can be eliminated. Along with this, the connector 6 can be downsized, and the wire harness for electrically connecting the low voltage side of the secondary winding 32 to the internal combustion engine does not crawl and the reliability of the device is improved.

Further, since the distance between the low voltage side of the secondary winding 32 and the ground electrode 23 of the spark plug 2 is shortened and the number of connection points is reduced, the resistance loss of the discharge circuit is reduced and the efficiency is improved. Good ignition is possible.

Further, one end of the pressure detecting element 4 is connected to the case 1
Since it is electrically connected to the internal combustion engine via the connector, a connector terminal and a wire harness for electrically connecting one end of the pressure detection element 4 to the internal combustion engine can be eliminated.

Further, the end portion of the coil side tubular portion 52 is projected to the side opposite to the combustion chamber from the primary winding 31 and the secondary winding 32, and the pressure detecting element 4 is provided at the end portion of the coil side tubular portion 52. Since it is arranged, the signal line of the pressure detection element 4 is connected to the ignition coil 3
It can be taken out of the case 1 without passing it by the side. Therefore, the diameter of the case 1 is not increased, the output signal of the pressure detection element 4 is less susceptible to the influence of the discharge noise from the ignition coil 3, and the processing such as the crawling of the signal line is unnecessary or easy. .

Further, since the compression preload is applied to the pressure detecting element 4 by tightening the bolt 8, it is possible to ensure the output accuracy with respect to the pressure fluctuation of the combustion chamber.

Further, the case 1 is tightened by tightening the bolt 8.
Since the contact surface 53 of the insulator 5 is pressed against the receiving surface 13 of the insulator 5, combustion gas is prevented from leaking between the case 1 and the insulator 5 at the contact portion between the receiving surface 13 and the contact surface 53. can do.

Further, since the case 1 including the portion for accommodating the ignition coil constituent parts is integrally formed of a metal material, the ignition coil constitution is better than the case where the ignition coil constituent parts are accommodated in the resin case. The heat dissipation of the parts can be improved.

Further, since the case 1 itself can be provided with the function of the outer peripheral core of the ignition coil, it is not necessary to separately provide an outer peripheral core as in the conventional case, and therefore the diameter of the ignition device can be reduced and the cost can be reduced. It will be possible.

Further, the slit 15 provided in the portion surrounding the central core 33 in the case 1 can prevent the loss due to the annular current generated by the change in the magnetic flux.

Further, since the windings 31, 32, etc. of the ignition coil 3 are covered with the metal case 1 which is grounded to the cylinder head, the ignition noise generated in the ignition coil 3 is shielded by the case 1. Hard to leak to the outside.

(Other Embodiments) In the above embodiments, the inner winding side is the secondary winding 32 and the outer circumference side is the primary winding 31, but the present invention is not limited to this. The outer peripheral side may be the secondary winding 32 and the inner peripheral side may be the primary winding 31.

In the above embodiment, the pressure detecting element 4 is preloaded by tightening the bolt 8. However, instead of the bolt 8, a holding member having no screw is used, and the holding member is used as the case 1. A preload may be applied to the pressure detection element 4 by press-fitting into the case or by caulking the case 1 after inserting the holding member into the case 1. Further, the holding member may be welded to the case 1 after the holding member is inserted into the case 1 and a preload is applied to the pressure detection element 4.

Further, the case 1 may be made by integrating the divided pieces by welding or the like. More specifically, for example, the part in which the components of the ignition plug 2 are housed and the part in which the components of the ignition coil 3 are housed may be separately formed, and they may be integrated by welding or the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an ignition device according to the present invention.

2 is an external perspective view of the ignition device of FIG. 1. FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of the ignition device in FIG.

[Explanation of reference numerals] 1 ... Case, 2 ... Spark plug, 22 ... Center electrode, 3 ... Ignition coil, 31 ... Primary winding, 32 ... Secondary winding, 5 ... Insulator.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) H01F 31/00 501A

Claims (3)

[Claims] 1. A spark plug (2) having a center electrode (22) built in a cylindrical insulator (5) for discharging in a combustion chamber of an internal combustion engine, a primary winding (31) and a secondary winding. (32) and an ignition coil (3) for supplying a high voltage to the ignition plug (2), wherein the ignition plug (2) and the ignition coil (3) are provided in a cylinder head of the internal combustion engine. In an internal combustion engine ignition device to be mounted, a tubular case in which a part in which the components of the spark plug (2) are housed and a part in which the components of the ignition coil (3) are housed are integrally formed. An ignition device for an internal combustion engine, comprising: (1), wherein the case (1) is made of a magnetic material and a conductive metal material. 2. The ignition coil (3) comprises a rod-shaped central core (33), and a portion of the case (1) surrounding the central core (33) extends in the axial direction of the central core (33). The ignition device for an internal combustion engine according to claim 1, wherein a slit (15) is formed. 3. The ignition device for an internal combustion engine according to claim 1, wherein the case (1) is electrically connected to the cylinder head.