Patent Grant
6946943
This application is based on and incorporates herein by reference Japanese Patent Applications No. 2004-49089 filed on Feb. 25, 2004 and No. 2004-327704 filed on Nov. 11, 2004.
The present invention relates to a stick-shaped ignition coil that generates high-voltage electric power supplied to an ignition plug, which ignites mixture gas in an internal combustion engine.
A stick-shaped ignition coil includes a coil portion, a control portion, and a tower portion. The coil portion is located in an axially intermediate position of the ignition coil. The control portion is located on the upper end side of the ignition coil. The tower portion is located on the lower end side of the ignition coil. The tower portion and the coil portion are inserted into a plughole formed in a cylinder head of the engine. The control portion protrudes from the upper plane of the cylinder head. The diameters of both the coil portion and the tower portion are determined to be slightly smaller than the inner diameter of the plughole, so that the coil portion and the tower portion can be easily inserted into the plughole. Specifically, the diameters of both the coil portion and the tower portion are within a range from 20 mm to 22 mm. The diameter of the control portion is within a range from 23 mm to 25 mm. Therefore, an annular gap is formed between the coil portion and the plughole, and another annular gap is formed between the tower portion and the plughole. The coil portion and the tower portion may be radially vibrated within the annular gap due to vibration of the engine. Accordingly, a radially positioning portion needs to be provided to the ignition coil to reduce vibration of the outer circumferential periphery of the coil portion with respect to the inner circumferential periphery of the plughole.
As shown in
However, the outer diameter of a coil portion of an ignition coil needs to be decreased, because of decrease of the inner diameter of the plughole in recent years. Therefore, the resinous case 101 is reduced from the conventional coil portion 100, and a thin film sheet is provided to the ignition coil instead of the resinous case 101. The thin film sheet is circumferentially covered with a metallic outer core that is exposed to the outermost periphery of the coil portion. In this structure, a positioning member may not be easily formed on the outer circumferential periphery of the metallic outer core. Accordingly, the coil portion may not be properly positioned in the plughole.
In view of the foregoing problems, it is an object of the present invention to produce a stick-shaped ignition coil that has a positioning portion for radially positioning a coil portion in the plughole, even when a metallic outer core is exposed to the outermost periphery of the coil portion to decrease the outer diameter of the coil portion.
According to the present invention, a stick-shaped ignition coil, which is received in a plughole formed in a cylinder head of an internal combustion engine, includes a coil portion, a first portion, and at least one first positioning portion.
The coil portion includes a center core, a secondary coil, primary coil, and an outer core. The secondary coil is arranged on the outer circumferential side of the center core. The secondary coil includes a secondary spool and a secondary winding. The secondary winding is wound around the secondary spool. The primary coil is arranged on the outer circumferential side of the center core. The primary coil includes a primary spool and a primary winding. The primary winding is wound around the primary spool. The secondary coil and the primary coil are substantially coaxially arranged. The outer core is arranged on the outer circumferential side of one of the primary coil and the secondary coil that is arranged on the outer circumferential side with respect to the other of the primary coil and the secondary coil. The outer core is arranged on the outermost side of the coil portion in the radial direction of the coil portion. The outer core has a middle portion that is located at the center of the outer core in the axial direction of the outer core. The first portion is connected to an upper end portion of the coil portion. The first portion is apart from the middle portion of the outer core in the axial direction of the outer core.
The at least one first positioning portion is formed on the first portion. The at least one first positioning portion is in proximity to the inner circumferential periphery of a first hole portion, which is formed in the plughole, in the radial direction of the plughole. Alternatively, the at least one first positioning portion makes contact with the inner circumferential periphery of the first hole portion, which is formed in the plughole, in the radial direction of the plughole.
The upper end portion of the coil portion is located on the opposite side as an ignition plug, which is inserted into a combustion chamber formed in the internal combustion engine, with respect to the outer core. The first portion is an upper case. The plughole has the first hole portion and a second hole portion. The first hole portion is formed on a side of an inlet of the plughole with respect of the second hole portion. The first hole portion is arranged on the opposite side as the combustion chamber of the internal combustion engine with respect to the second hole portion. The first hole portion has the inner diameter that is greater than the inner diameter of the second hole portion. The first portion is at least partially received in the first hole portion. The at least one first positioning portion is formed on the outer circumferential periphery of the first portion such that the at least one first positioning portion is at least partially received in the first hole portion. The at least one first positioning portion is at least partially in proximity to the inner circumferential periphery of the first hole portion in the radial direction of the plughole.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
As shown in
The ignition coil 60 inserted into the plughole 65 includes a coil portion 10, a control portion 40, and a tower portion 50. The coil portion 10 is located in an axially intermediate position of the ignition coil 60. The control portion 40 is located on one end (upper end) side of the ignition coil 60. The tower portion 50 is located on the other end (lower end) side of the ignition coil 60. The tower portion 50 and the coil portion 10 are inserted into the small-diameter long hole 66. The control portion 40 is partially received in the large-diameter short hole 67.
As shown in
As shown in
As referred to
A thin outer core 23, which is small in thickness, is provided on the side of the outer periphery of the thin film sheet 22. That is, the thin outer core 23 is arranged on the radially opposite side as the primary winding 19 with respect to the thin film sheet 22 such that the thin outer core 23 entirely covers the primary winding 19. The outer core 23 forms the outermost portion of the coil portion 10 such that the outer core 23 is exposed to the outermost periphery of the coil portion 10. The outer diameter of the coil portion 10 is within a range from substantially 15 mm to substantially 21 mm. As shown in
The terminal assembly 30 shown in
The upper end portion of the secondary winding 15 upwardly extends to the upper end plane of the upper end portion 31 of the terminal assembly 30 through a hollow portion of the upper end portion 31, and the end portion of the secondary winding 15 is electrically connected with a primary terminal (not shown). The upper end portion of the primary winding 19 upwardly extends over the collar portion 25 of the primary spool 18 to the upper end plane of the upper end portion 31 of the terminal assembly 30 through a hollow portion of the upper end portion 31. The end portion of the primary winding 19 is electrically connected with a secondary terminal (not shown).
Gaps, which are formed in the coil portion 10, such as a gap formed between the secondary winding 15 and the primary spool 18, and a gap formed between the primary winding 19 and the thin film sheet 22 are filled with electrically insulative resin. The intermediate portion 32 of the terminal assembly 30 tightly makes contact with the outer circumferential periphery of the thin film sheet 22, which extends to the upper end of the primary spool 18, so that the intermediate portion 32 seals a space formed between the primary winding 19 and the thin film sheet 22.
The upper case 41 of the control portion 40, which serves as a circuit case, includes a receiving portion 42, a connector portion 43, and the connecting portion 44. The upper case 41 is electrically insulative. An igniter 46 is arranged in the receiving portion 42 of the upper case 41, which is formed in a box shape. A terminal 47 is provided to the inside of the connector portion 43 that extends from the minus side of the receiving portion 42. The terminal 47 is electrically connected with both the igniter 46 and the other end portion of the primary winding 19. The space around the igniter 46 in the receiving portion 42 is filled with an electrically insulative resin (not shown).
The connecting portion 44, which extends from the lower plane of the receiving portion 42, is in a substantially cylindrical shape. The inner diameter of the connecting portion 44 is substantially the same as the outer diameter of the upper end portion 31 of the terminal assembly 30. The terminal assembly 30 is press-inserted into the primary spool 18, and the connecting portion 44 is press-inserted into the terminal assembly 30, so that the control portion 40 is fixed to the coil portion 10.
As shown in
All the axial protrusions 48 are in a substantially the same shape such as a substantially semicircular shape in cross section. The axial protrusion 48 extends in parallel with the axis of the connecting portion 44. The axial protrusions 48 are arranged in the circumferential direction of the connecting portion 44 at predetermined intervals.
As referred to
The tower portion (high-voltage tower portion) 50 shown in
An annular protrusion (lower positioning portion, second positioning portion) 58 is formed on the outer circumferential periphery of the connecting portion 53. The annular protrusion 58 may be formed simultaneously with forming of the connecting portion 53. That is, the second positioning portion 58 is formed on the integrated member that is formed of the tower case 51, the primary spool 18, and the connecting portion 53.
The annular protrusion 58 is formed to be in a substantially semicircular shape in cross-section with respect to the circumferential direction thereof. The height of the annular protrusion 58 is in a range from substantially 0.5 mm to substantially 2.0 mm. The tip end of the annular protrusion 58 on the radially outer side thereof makes contact with the inner periphery of the small-diameter long hole 66 of the plughole 65. Alternatively, the tip end of the annular protrusion 58 on the radially outer side thereof is in proximity radially to the inner periphery of the small-diameter long hole 66 of the plughole 65.
The tower case 51 is inserted into a cylindrical concavity 56 formed in the upper end portion of the rubber cap 55. The spring 57 is provided to a hollow space that is axially formed through the tower case 51 and the rubber cap 55.
As referred to
Next, an assemble process of the stick-shaped ignition coil is described in reference to
Lead portions of both the primary and secondary windings 19, 15 are upwardly drawn from the upper end plane of the terminal assembly 30 through a hollow space formed in the terminal assembly 30. The lead portion of the primary winding 19 is electrically connected to the primary terminal provided to the terminal assembly 30. The lead portion of the secondary winding 15 is electrically connected to the secondary terminal. The lead portion of the primary winding 19 is electrically connected to the igniter 46 and the terminal 47 that are received in the control portion 40.
Subsequently, the secondary coil 13 is inserted into the inner circumferential periphery of the primary coil 17. The center core 11 is inserted into the inner circumferential periphery of the secondary coil 13. The igniter 46 and the terminal 47 are arranged in the upper case 41 of the control portion 40 in advance. The connecting portion 44 of the upper case 41 is press-inserted into the outer circumferential periphery of the terminal assembly 30. In this situation, melted resin is injected into a space formed in the upper case 41, so that the melted resin flows over the space in the upper case 41. Thus, gaps such as the gap formed between the secondary winding 15 and the primary spool 18, and the gap formed between the primary winding 19 and the thin film sheet 22 can be filled with the melted resin. The control portion 40 is connected with the coil portion 10.
The ignition coil 60, which is completely assembled, is inserted into the plughole 65 formed in the cylinder head 70 from the side of the tower portion (high-voltage tower portion) 50. The ignition coil 60 is inserted into the plughole 65, so that the tip end of the annular protrusion 58, which is formed on the connecting portion 53 (
Thus, the ignition coil 60, specifically the coil portion 10 can be radially set at the predetermined position in the plughole 65. The coil portion 10 is in a long slender shape, and a gap is formed between the outer circumferential periphery of the coil portion 10 and the inner circumferential periphery of the small-diameter long hole 66 of the plughole 65. However, even in this structure, the upper and lower end portions of the coil portion 10 can be positioned in the radial direction thereof using the annular protrusion 58 and the axial protrusions 48, so that coil portion 10 can be restricted from radially moving in the plughole 65.
As referred to
As referred to
The intermediately outer periphery of the coil portion 10 is formed of the thin film sheet 22, and the outermost periphery of the coil portion 10 is formed of the outer core 23. The outer circumferential periphery of the coil portion 10 is exposed without being covered with a cylindrical resinous case, i.e., coil case. The thickness of the thin film sheet 22 is substantially half or substantially one-third of the thickness of a conventional coil case. Therefore, the outer diameter of the coil portion 10 can be significantly reduced in the above structure.
The primary spool 18 of the coil portion 10 is connected with the upper case 41 of the control portion 40 via the terminal assembly 30. Specifically, the upper end portion of the primary spool 18 of the coil portion 10 is press-inserted into the terminal assembly 30, and the upper case 41 of the control portion 40 is press-inserted into the terminal assembly 30. Therefore, shortage of rigidity of the thin film sheet 22 can be compensated by the rigid structure of the entire coil portion 10. Thus, the coil portion 10, which has the intermediately outer periphery formed of the thin film sheet 22, can be steadily connected with the control portion 40.
The terminal assembly 30 seals the gap formed between the primary spool 18 and the thin film sheet 22. Besides, the terminal assembly 30 seals the gap formed between the primary spool 18 and the upper case 41. Therefore, the electrically insulative resin such as epoxy resin injected into the space formed in the coil portion 10 can be protected from leakage through the gaps.
As shown in
The positioning portions 48, 58, 82, i.e., the axial protrusions 48, the annular protrusions 58, 82 are respectively formed on axially intermediate portions of the ignition coil 60. The axially intermediate portions of the ignition coil 60 are axially apart from the axially middle portion of the ignition coil 60 in the axial direction of the ignition coil 60. The axially middle portion of the ignition coil 60 is located in the center of the ignition coil 60 in the axial direction of the ignition coil 60. Thus, the outer core 23 of the ignition coil 60 can be stably positioned in the radial direction of the plughole 65 by the positioning portions 48, 58, 82.
The ignition coil 60 can be stably positioned in the plughole 65 by the upper case 41 of the control portion 40 without reducing the length of the coil portion 10 in the above structure of the ignition coil 60.
The annular protrusion 58 is proximity to or makes contact with the inner periphery of the small-diameter long hole 66 at an intermediate portion between the coil portion 10 and the tower portion 50. The intermediate portion between the coil portion 10 and the tower portion 50 is located at a substantially middle position of the total length of both the coil portion 10 and the tower portion 50. Thus, the ignition coil 60 can be stably positioned by the annular protrusion 58.
The cylinder head 70 constructs a lid member of a cylinder block of the internal combustion engine 200 for an automobile such as a vehicle. The plughole 65 is formed in the cylinder head 70 in the direction of the thickness of the cylinder head 70. The plughole 65 includes the large-diameter short hole 67 and the small-diameter long hole 66. The large-diameter short hole 67 is located on the side of the inlet, i.e., opening of the plughole 65. That is, the large-diameter short hole 67 is located on the opposite side as the combustion chamber 220, which is formed in the internal combustion engine 200, with respect to the small-diameter long hole 66.
The small-diameter long hole 66 is located on the side of the intermediate portion of the plughole 65, or located on the side of the deep portion of the plughole 65. The control portion 40 is at least partially inserted to the large-diameter short hole 67, so that the control portion 40 is at least partially received in the large-diameter short hole 67. The length of the large-diameter short hole 67 in the axial direction of the plughole 65 may be small, however, the inner diameter of the large-diameter short hole 67 needs to be large. The coil portion 10 and the tower portion 50 are inserted into the small-diameter long hole 66 of the plughole 65. The inner diameter of the small-diameter long hole 66 may be small, however, the length of the small-diameter long hole 66 in the axial direction of the plughole 65 needs to be large.
The center core 11 and the outer core 23 are made of a magnetic material. The outer core 23 is substantially coaxially arranged with respect to the center core 11 on the radially outer side of the center core 11, so that the outer core 23 and the center core 11 form a closed magnetic circuit. Any member is not provided to the radially outer side of the outer core 23, so that the outer circumferential periphery of the outer core 23 exposes to the outermost periphery of the coil portion 10. Thus, the outer diameter of the coil portion 10 becomes small.
The terminal assembly 30, which is formed in a substantially cylindrical shape, has a predetermined length in the axial direction of the terminal assembly 30. The inner periphery of the terminal assembly 30 has a predetermined shape and a predetermined dimension, so that the terminal assembly 30 can be stably press-inserted to the primary spool 18. The outer periphery of the terminal assembly 30 has a predetermined shape and a predetermined dimension that are suitable to be press-inserted into the upper case 41 of the control portion 40. The outer diameter of the outer periphery of the terminal assembly 30 and the inner diameter of the inner periphery of the terminal assembly 30 may be uniform over the total axial length of the terminal assembly 30, and may be changed lengthwise in the terminal assembly 30.
The cylindrical thin film sheet 22, which is electrically insulative, has a thickness, which is in a range from substantially 0.1 mm to substantially 0.3 mm.
The control portion 40, which switches primary current supplied to the primary coil 17, may be directly connected to the coil portion 10 without providing the connecting portion 44 therebetween.
The tower portion 50, which supplies the ignition plug 210 with high-voltage secondary current, may be connected to the primary spool 18 via a tower case 51 that is separate from both the tower portion 50 and the primary spool 18. The tower portion 50 may be integrally formed directly with the primary spool 18.
The positioning portions 48, 58, 82 are formed on portions of the ignition coil 60, which are away from the axially middle portion of the outer core 23. The positioning portions 48, 58, 82 may be formed at a portion that is completely apart from the outer core 23 in the axial direction of the outer core 23. Alternatively, the positioning portions 48, 58, 82 may be formed on axial end portions of the outer core 23 of the ignition coil 60. The outer core 23 may be arranged substantially over the entire portion of the coil portion 10 lengthwise. In this structure, at least one of the axial protrusions 48, the annular protrusion 82, and the annular protrusion 58, which are positioned to be upwardly and downwardly away from the middle portion of the outer core 23, are arranged at both the upper and lower end portions of the coil portion 10. Alternatively, in this structure, at least one of the axial protrusions 48, the annular protrusion 82, and the annular protrusion 58 may be arranged in the vicinities of both the upper and lower end portions of the coil portion 10.
Specifically, the axial protrusions 48 and/or the annular protrusion 82 may be arranged at the upper case 41 that is located on the upper side, i.e., the side of the control portion 40 axially apart from the outer core 23. The annular protrusion 58 may be arranged at a connecting portion 53 that is located on the lower side in
The connecting portion 53 is included in the coil portion 10 and/or the tower portion 50. The connecting portion 53 radially oppose to the small-diameter long hole 66 of the plughole 65. When the primary spool 18 of the coil portion 10 is a member, which is separate from the tower case 51 of the tower portion 50, the annular protrusion 58 may be formed on at least one of the primary spool 18 and the tower case 51. Specifically, the annular protrusion 58 may be formed in the vicinity of the lower end portion of the primary spool 18. Besides, the annular protrusion 58 may be formed in the vicinity of the upper end portion of the tower case 51. When the primary spool 18 is integrated with the tower case 51, the annular protrusion 58 may be formed on a portion that is in a boundary between the primary spool 18 and the tower case 51. That is, the tower case 51 is integrally formed with the primary spool 18 to be an integrated member 18, 14, and the second positioning portion 58 may be formed on the integrated member 18, 14.
The annular protrusion 58 is constructed of at least one annular protrusion that substantially circumferentially extends. At least one lib 58, which substantially axially extends, may be formed on the ignition coil 60 instead of the annular protrusion 58. Alternatively, at least one lib 58 may be formed in addition to the annular protrusion 58. The annular protrusion 58 need not to be formed on the ignition coil 60. Even when the annular protrusion 58 is not formed on the ignition coil 60, the axial end portion of the tower portion 50 is connected to the ignition plug 210, so that the connection between the end portion of the tower portion 50 and the ignition plug 210 may become a rigid positioning structure.
The primary coil 17 may be arranged on the inner peripheral side with respect to the secondary coil 13 in the radial direction of the coil portion 10. Even in this structure, current can be supplied and shut by the igniter 46, so that high-voltage current can be generated using the primary and secondary coils 13, 17, as well as a generally known ignition coil.
A resinous cylindrical member may be provided between the primary spool 18 and the outer core 23.
Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-049809 | Feb 2004 | JP | national |
| 2004-327704 | Nov 2004 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6011457 | Sakamaki et al. | Jan 2000 | A |
| 6622712 | Nakashima et al. | Sep 2003 | B2 |
| 6639498 | Shimada et al. | Oct 2003 | B2 |
| Number | Date | Country |
|---|---|---|
| A-9-222067 | Nov 1996 | JP |
| B2-3393770 | Mar 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20050184845 A1 | Aug 2005 | US |
