JPH11173249A - Ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil which prevents an elastic member electrically connecting the high voltage side of a secondary coil with an ignition plug from getting caught on the inner periphery of a rubber cap following attaching/detaching of the ignition coil, and impresses a desired high voltage onto an ignition device. SOLUTION: This ignition coil 10 is formed in the stick shape and is loaded directly on a plug hole. A rib 13b is formed on the inner peripheral wall of a second case 13 of the ignition coil 10. Since a spring 42 expands due to a guide by the rib 13b even when one end 42b of the spring 42 passes through a tip 15d of an inner periphery 15b following attaching/detaching of the ignition coil 10, the spring 42 does not get caught on the inner periphery 15b. Thus, since insulation destruction is prevented from occurring between the spring 42 and an engine block positioned near the outer periphery of the ignition coil, a desired high voltage can be impressed onto an ignition plug.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil, and more particularly to a stick-shaped ignition coil directly mounted on a plug hole.

[0002]

2. Description of the Related Art A conventional stick-shaped ignition coil is shown in FIG.
And FIG. Since the ignition coil 100 is directly mounted on a plug hole formed in the engine block, the engine block is located near the outer periphery of the ignition coil 100. The case 101 is made of resin and houses a primary coil and a secondary coil (not shown). The high voltage terminal 103 is electrically connected to the high voltage side of the secondary coil, and one end 104 a of the spring 104 is electrically connected to the high voltage terminal 103. Rubber cap 1
02 is fitted to the high voltage side end of the case 101, and the ignition plug 110 is fitted to the rubber cap 102.
When the ignition plug 110 is inserted into the rubber cap 102, the other end 104 b of the spring 104 and the coil side terminal 111 of the ignition plug 110 come into contact and the spring 104 is compressed, and the high-voltage terminal 103 and the ignition plug 110 are electrically connected. I do. Spark plug 11 on rubber cap 102
0, the other end 1 of the spring 104 is inserted.
04b is the tip 1 of the inner peripheral portion 102a of the rubber cap 102.
02b is located on the compression direction side of the spring 104.

[0003]

When the ignition coil 100 is pulled out, for example, obliquely from the ignition plug 110, as shown in FIG. 7, the spring 104 is extended and the spring 104 is attached to the tip 102b of the inner peripheral portion 102a. The other end 104b may be caught. When the ignition plug 110 is fitted into the rubber cap 102 in such a state,
Since the spring 104 is pushed in a bent state, the spring 104 and the engine block locally approach each other. Since the engine block maintained at the ground voltage is located near the outer periphery of the rubber cap 102, the spring 104 is bent in a state where the spring 104 is bent.
When a high voltage is applied to the spark plug 110, a dielectric breakdown is likely to occur at a location where the spring 104 and the engine block are locally approached. Therefore, there is a problem that a desired high voltage cannot be applied to the ignition plug 110.

An object of the present invention is to prevent an elastic member for electrically connecting a high voltage side of a secondary coil and an ignition plug from being caught on an inner peripheral portion of a rubber cap due to attachment / detachment of an ignition coil. It is to provide an ignition coil for applying a high voltage to a spark plug.

[0005]

According to the ignition coil of the present invention, the other end of the elastic member electrically connected to the ignition plug when the ignition plug is inserted into the rubber cap is connected to the rubber cap. When the ignition plug is inserted into the rubber cap, the other end of the elastic member is located at the tip of the inner peripheral portion when the ignition plug is inserted into the rubber cap. It is located on the compression direction side of the elastic member. Therefore, when the elastic member expands and contracts with the attachment and detachment of the ignition coil, the other end of the elastic member passes through the tip of the inner peripheral portion.

Since the ignition coil according to the first aspect of the present invention includes a guide member for guiding the elastic member when the elastic member expands and contracts, the elastic member extends from a compressed state when the ignition coil is removed from the ignition plug. However, since the elastic member is guided by the guide member, the elastic member does not catch on the inner peripheral portion. Therefore, even if the elastic member expands and contracts, the radial position of the elastic member does not change, so that the elastic member is prevented from locally approaching the low-voltage member located near the outer periphery of the ignition coil.
Thereby, insulation between the elastic member and the low-voltage member is maintained, so that a desired high voltage can be applied to the ignition plug.

According to the ignition coil according to the second aspect of the present invention, since the guide member is formed integrally with the case, the number of parts is reduced, and the assembly of the ignition coil is facilitated. According to the ignition coil according to the third aspect of the present invention, the guide member is provided between at least the distal end position of the inner peripheral portion and the other end position of the elastic member when the ignition plug is inserted into the rubber cap. . Therefore, it is possible to reliably prevent the elastic member from being caught on the inner peripheral portion.

[0008] According to the ignition coil according to claim 4 of the present invention, when the inner diameter of the inner peripheral portion d _1, the inner diameter of the guide member and d _2, the guide member has a portion serving as d ₂ ≦ d _1. Therefore, the elastic member is prevented from being displaced radially outward from the inner peripheral surface of the inner peripheral portion, so that the elastic member can be reliably prevented from being caught on the inner peripheral portion. According to the ignition coil according to the fifth aspect of the present invention, the guide member is constituted by a rib extending substantially from the elastic member side end of the high voltage terminal to the tip of the inner peripheral portion. Therefore, it is possible to prevent the elastic member from being bent between the high-voltage terminal and the tip of the inner peripheral portion. Furthermore, since the wall pressure of the guide member can be reduced, distortion and cavities generated when the guide member is formed of resin can be reduced.

According to the ignition coil of the present invention, the other end of the elastic member for electrically connecting the high voltage side of the secondary coil and the ignition plug is in a state where the ignition plug is inserted into the rubber cap. Is located closer to the extension direction of the elastic member than the tip of the inner peripheral portion. Therefore, even if the elastic member expands and contracts with the attachment and detachment of the ignition coil, the other end of the elastic member does not pass through the tip of the inner peripheral portion, so that the elastic member can be reliably prevented from being caught on the inner peripheral portion. Therefore, since the elastic member is prevented from locally approaching the low-voltage member located near the outer periphery of the ignition coil, insulation between the elastic member and the low-voltage member is maintained, and a desired high voltage is applied to the ignition plug. can do.

According to the ignition coil of the present invention, the other end of the elastic member electrically connected to the ignition plug before the ignition plug is inserted into the rubber cap is connected to the inner peripheral portion of the rubber cap. It is located on the compression direction side of the elastic member from the tip. Therefore, even if the elastic member expands and contracts with the attachment and detachment of the ignition coil, the other end of the elastic member does not pass through the tip of the inner peripheral portion, so that the elastic member can be reliably prevented from being caught on the inner peripheral portion. Therefore, since the elastic member is prevented from locally approaching the low-voltage member located near the outer periphery of the ignition coil, insulation between the elastic member and the low-voltage member is maintained, and a desired high voltage is applied to the ignition plug. can do.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIGS. 1, 2 and 3 show an ignition coil according to a first embodiment of the present invention. Ignition coil 1 shown in FIG.
Numeral 0 is housed in a plug hole formed for each cylinder above an engine block (not shown), and is electrically connected to a spark plug (not shown) below in FIG.

The case 11 of the ignition coil 10 comprises a first case 12 and a second case 13, and is formed of a resin material in a cylindrical shape. The first case 12 includes the central core 1
6, magnets 17, 18, secondary spool 20, secondary coil 2
1, a terminal plate 40 electrically connected to the secondary coil 21, a primary spool 23, a primary coil 24, an outer core 25, and the like are housed. The second case 13 houses a high voltage terminal 41 and a spring 42 as a high voltage part. The epoxy resin 26 filled in the case 11 penetrates between the members in the ignition coil 10 to ensure electrical insulation between the members as a resin insulating material. A plug cap 14 as a rubber cap is fitted to the high voltage side end of the second case 13. Plug cap 14
The spring 42 as an elastic member electrically connects the high voltage side of the secondary coil 21 to the spark plug by inserting the spark plug into one end of the spark plug.

The cylindrical central core 16 is assembled by laminating thin silicon steel plates in the radial direction so that the cross section is substantially circular. Magnets 17 and 18 having polarities opposite to the direction of the magnetic flux generated by the excitation of the coil are mounted on both ends of the central core 16 in the axial direction. Further, a rubber material 19 covers the outer periphery of the central core 16 as an insulating material.

The secondary spool 20 is provided on the outer periphery of the rubber material 19 and is formed of a resin material. The secondary coil 21 is wound around the outer periphery of the secondary spool 20, and a dummy coil 22 is further wound around the high voltage side of the secondary coil 20 in a single winding. The dummy coil 22 electrically connects the secondary coil 21 and the terminal plate 40. Secondary coil 2 with dummy coil 22 instead of single wire
By electrically connecting 1 to terminal plate 40, the surface area of the electrical connection between secondary coil 21 and terminal plate 40 is increased, and electric field concentration on the electrical connection is avoided.

The primary spool 23 is provided on the outer periphery of the secondary coil 21 and is formed of a resin material. The primary coil 24 is wound around the primary spool 23.
The outer core 25 is mounted further outside the primary coil 24. The outer peripheral core 25 is formed by winding a thin silicon steel sheet in a cylindrical shape and does not connect the winding start end and the winding end end, so that a gap is formed in the axial direction. The outer peripheral core 25 has an axial length extending from the outer peripheral position of the magnet 17 to the outer peripheral position of the magnet 18.

A connector 30 for inputting control signals is provided at the low voltage end of the secondary spool 20 so as to protrude from the plug hole. Plural terminals 31 connected to the ground side of primary coil 21 and primary coil 24
Are insert-molded. The igniter 32 supplies a control signal to the primary coil 24.

The high-voltage terminal 41 is insert-molded in the second case 13. The central portion of the terminal plate 40 forms a claw portion bent in the direction in which the high-voltage terminal 41 is inserted. High voltage terminal 4
The high-voltage terminal 41 is electrically connected to the terminal plate 40 by inserting the tip of the terminal 1. The wire at the high voltage end of the dummy coil 22 is electrically connected to the terminal plate 40 by fusing or soldering.

In the state shown in FIG. 1 before the spark plug is inserted into the plug cap 14, the other end 42b of the spring 42 is larger than the tip 15d of the inner peripheral portion 15b.
2 in the direction of extension. One end 42 a of the spring 42 is electrically connected to the high voltage terminal 41.
When the ignition plug is inserted into the ignition coil 10, the other end 42b of the spring 42 is electrically connected to the ignition plug, so that the spring 42 electrically connects the high voltage terminal 41 to the ignition plug. When a control signal is supplied from the igniter 32 to the primary coil 24, a high voltage is generated in the secondary coil 21, and this high voltage is applied to the ignition plug via the dummy coil 22, the terminal plate 40, the high voltage terminal 41, and the spring 42. .

Next, the second case 13 and the plug cap 1
4 will be described in detail. As shown in FIG. 1, an annular projection 13 a is formed on the outer peripheral wall of the second case 13 fitted with the plug cap 14. Projection 13a
Is formed to prevent the plug cap 14 fitted to the second case 13 from coming off. On the inner peripheral wall of the second case 13, the tip 15 d of the inner peripheral portion 15 b of the plug cap 14 is almost
Up to this point, six ribs 13b are formed as shown in FIG. As shown in FIG. 1, the rib 13b is
In order to facilitate the work of assembling the spring 42 with the spring 1, the spring 42 is formed in a tapered shape whose diameter decreases from the spark plug side toward the high-voltage terminal 41.

A fitting portion 15 formed at the other end of the plug cap 14 is fitted to the second case 13, and has a cylindrical outer peripheral portion 15a and an inner peripheral portion 15b, respectively.
Having. The high voltage side end of the second case 13 is fitted in an annular gap 15c formed between the outer peripheral portion 15a and the inner peripheral portion 15b. The inner peripheral portion 15b is in contact with the inner peripheral wall surface at the end on the high voltage side of the second case 13, and the plug cap 1
In the state where the ignition plug is inserted into the ignition plug 4, an insulation creepage distance between the ignition coil side terminal of the ignition plug and the engine block as a low voltage member which is located near the outer periphery of the ignition coil and held at the ground voltage is secured. It is provided for. In order to facilitate the fitting between the plug cap 14 and the second case 13, the inner peripheral portion 15b has a shorter axial length than the outer peripheral portion 15a within a range where the insulation creepage distance can be ensured.

Next, the operation of the ignition coil 10 when attaching and detaching the ignition coil 10 will be described. (1) When the ignition plug is inserted into the ignition coil 10 in the state shown in FIG. 1, the spring 42 is compressed, and the other end 42b of the spring 42 is located closer to the compression direction of the spring 42 than the tip 15d.

(2) When the ignition coil 10 is pulled out of the ignition plug, for example, when the ignition coil 10 is pulled out in an oblique direction, the spring 42 shifts in the radial direction as the ignition coil 10 comes out of the ignition plug, and comes into contact with the rib 13b. Sometimes. However, the inner diameter d ₂ of the ribs 13b the inner periphery 1
Since 5b is the inner diameter d ₁ below, the distal end of the inner peripheral portion 15b and the other end 42b of the spring 42 by the spring 42 is guided by the rib 13b is also in contact with the rib 13b 15
It returns to the state shown in FIG. 1 without being caught by d.

[0023] In the first embodiment, is formed continuously rib 13b to the tip 15d of the inner peripheral portion 15b from the spring-side end portion of the high-tension terminal 41, the inner diameter d ₁ of the inner diameter d ₂ is the inner peripheral portion 15b of the rib 13b Therefore, even if the ignition coil 10 is removed from the ignition plug, the spring 42
b is reliably prevented from being caught. Furthermore, rib 1
Since the thickness of 3b is thin, the rib 13 is formed together with the second case 13.
Even if b is integrally formed of resin, it is possible to reduce distortion of the rib 13b and generation of a cavity in the rib 13b.

Further, since the rib 13b is formed in a tapered shape so as to increase in diameter from the end of the high-voltage terminal 40 insert-molded in the second case 13 toward the open end.
The second case 13 can be molded. In the first embodiment, the rib 13b extending from the spring-side end of the high-voltage terminal 41 to the tip 15d of the inner peripheral portion 15b is formed as a guide member on the inner peripheral wall of the second case 13, but the spring pitch of the spring 42 during compression is reduced. The length of the spring 42 is longer than that of the
The guide member may be formed in a circular shape, for example, as long as the guide member can be prevented from being caught on the inner peripheral portion 15b. Further, a guide member may be used in which the inner peripheral wall has a circular cross section so as to satisfy d ₂ ≦ d ₁ without forming irregularities in the circumferential direction of the second case. In the first embodiment, the inner diameter d ₂ of the ribs 13b are all formed so as to satisfy d ₂ ≦ d _1, only a portion may be formed so as to satisfy d ₂ ≦ d _1.

(Second Embodiment) FIG. 4 shows an ignition coil according to a second embodiment of the present invention. Components substantially the same as those in the first embodiment are denoted by the same reference numerals. The inner peripheral wall of the fitting portion of the second case 50 to be fitted with the plug cap 51 is formed to have substantially the same diameter. The fitting portion 52 of the plug cap 51 fitted to the second case 50 includes an outer peripheral portion 52 a and an inner peripheral portion 5.
2b, and the high-voltage side end of the second case 50 is fitted in an annular gap 52c formed between the outer peripheral portion 52a and the inner peripheral portion 52b. The outer peripheral portion 52a and the inner peripheral portion 52b extend with substantially the same length.

Even if the ignition plug is inserted into the plug cap 51 of the ignition coil in the state shown in FIG. 4, the other end 42b of the spring 42 is located closer to the extension direction of the spring 42 than the other end 52d of the inner peripheral portion 52b. . Therefore, even if the spring 42 expands and contracts with the attachment and detachment of the ignition coil, the other end 42b of the spring 42 is always located on the extension direction side of the spring 42 beyond the tip 52d of the inner peripheral portion 52b. Regardless of the spring 42,
b is prevented from being caught.

(Third Embodiment) FIG. 5 shows an ignition coil according to a third embodiment of the present invention. Components substantially the same as those in the first embodiment are denoted by the same reference numerals. The inner peripheral wall of the fitting portion of the second case 55 to be fitted with the plug cap 56 has substantially the same diameter. The fitting portion 57 of the plug cap 56 fitted to the second case 55 includes an outer peripheral portion 57 a and an inner peripheral portion 5.
7b, and the high voltage side end of the second case 55 is fitted into an annular gap 57c formed between the outer peripheral portion 57a and the inner peripheral portion 57b.

In the state shown in FIG. 5 in which the ignition coil is removed from the ignition plug, the other end 42b of the spring 42 is located closer to the compression direction of the spring 42 than the tip 57d of the inner peripheral portion 57b. Therefore, even if the spring 42 expands and contracts with the attachment and detachment of the ignition coil, the other end 4 of the spring 42
Since 2b is always located on the compression direction side of the spring 42 with respect to the tip 57d of the inner peripheral portion 57b, the spring 42 is prevented from being caught on the inner peripheral portion 57b regardless of the attachment / detachment of the ignition coil.

In the above-described embodiments of the present invention, since the spring 42 does not catch on the plug cap even when the attachment and detachment of the ignition coil are repeated, the engine block located near the outer periphery of the ignition coil held at the ground voltage. Part of the spring 42, which is a high voltage member, is prevented from locally approaching. Therefore, the spring 4
Since it is possible to prevent the occurrence of insulation breakdown between the engine block 2 and the engine block, it is possible to apply a desired high voltage to the ignition plug.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a high voltage side of an ignition coil according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view showing an ignition coil according to the first embodiment.

FIG. 4 is a sectional view showing a high voltage side of an ignition coil according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a high voltage side of an ignition coil according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a connection state between a conventional ignition coil and a spark plug.

FIG. 7 is a cross-sectional view showing a state where a conventional ignition coil is removed from an ignition plug.

[Explanation of symbols]

 Reference Signs List 10 ignition coil 11 case 12 first case 13 second case 13b rib (guide member) 14 plug cap (rubber cap) 15 fitting portion 15a outer peripheral portion 15b inner peripheral portion 15c annular gap 15d tip 16 center core 20 secondary spool 21 Secondary coil 23 Primary spool 24 Primary coil 40 Terminal plate 41 High voltage terminal 42 Spring (elastic member) 42a One end 42b Other end 50, 55 Second case 51, 56 Plug cap (rubber cap) 52, 57 Fitting portion 52a, 57a Outer peripheral part 52b, 57b Inner peripheral part 52c, 57c Annular gap 52d, 57d Tip

Claims (7)

[Claims] 1. A stick-shaped ignition coil for generating a high voltage to be applied to an ignition plug of an internal combustion engine, comprising: a primary coil and a secondary coil; a cylindrical case accommodating both the coils; The ignition plug is inserted into the case, the other end has a fitting portion that fits with the high-voltage side end of the case, and an inner peripheral portion that contacts an inner peripheral wall surface of the high-voltage side end. The rubber cap of the fitting portion is electrically connected at one end to the high voltage side of the secondary coil, and the other end of the secondary coil comes into contact with the ignition plug when the ignition plug is inserted into the rubber cap. And an elastic member for electrically connecting the high voltage side of the secondary coil and the ignition plug, wherein the elastic member is in a state before the ignition plug is inserted into the rubber cap. The other end is from the tip of the inner periphery The other end of the elastic member is located on the compression direction side of the elastic member with respect to the tip of the inner peripheral portion in a state where the ignition plug is inserted into the rubber cap and is located on the extension direction side of the elastic member. An ignition coil, comprising: an elastic member configured to move; and a guide member that guides the elastic member when the elastic member expands and contracts. 2. The ignition coil according to claim 1, wherein the guide member is formed integrally with the case. 3. The guide member is provided at least between the distal end position of the inner peripheral portion and the other end position of the elastic member in a state where the ignition plug is inserted into the rubber cap. 3. The method according to claim 1, wherein
The ignition coil as described. 4. d ₁ the inner diameter of the inner peripheral portion, the inner diameter of the guide member when the d _2, according to claim 1 wherein the guide member is characterized by having a portion serving as d ₂ ≦ d ₁ Or 3
The ignition coil as described. 5. A high voltage terminal for electrically connecting a high voltage side of the secondary coil and the one end of the elastic member, wherein the guide member is substantially connected to the elastic member side end of the high voltage terminal. The ignition coil according to any one of claims 1 to 4, wherein the ignition coil is a rib extending to the tip of an inner peripheral portion. 6. A stick-shaped ignition coil for generating a high voltage to be applied to an ignition plug of an internal combustion engine, comprising: a primary coil and a secondary coil; a cylindrical case accommodating both the coils; The ignition plug is inserted into the case, the other end has a fitting portion that fits with the high-voltage side end of the case, and an inner peripheral portion that contacts an inner peripheral wall surface of the high-voltage side end. The rubber cap of the fitting portion is electrically connected at one end to the high voltage side of the secondary coil, and the other end of the secondary coil comes into contact with the ignition plug when the ignition plug is inserted into the rubber cap. An elastic member that electrically connects the high voltage side of the secondary coil and the ignition plug, and the other end of the elastic member has the ignition plug fitted into the rubber cap. In the state than the tip of the inner peripheral part Ignition coil and being located in the extension direction of the serial elastic member. 7. A stick-shaped ignition coil for generating a high voltage to be applied to an ignition plug of an internal combustion engine, comprising: a primary coil and a secondary coil; a cylindrical case accommodating both the coils; The ignition plug is inserted into the case, the other end has a fitting portion that fits with the high-voltage side end of the case, and an inner peripheral portion that contacts an inner peripheral wall surface of the high-voltage side end. The rubber cap of the fitting portion is electrically connected at one end to the high voltage side of the secondary coil, and the other end of the secondary coil comes into contact with the ignition plug when the ignition plug is inserted into the rubber cap. And an elastic member for electrically connecting the high voltage side of the secondary coil and the ignition plug, and the other end of the elastic member is fitted with the ignition plug in the rubber cap. In the previous state, Ignition coil characterized in that it also located in the compression direction of the elastic member.