Ignition coil

Abstract

An ignition coil (2) according to one embodiment is provided with a primary coil (16), a secondary coil (18), a rod-shaped resistor (28), and a high-voltage terminal (22) that electrically connects the output of the secondary coil (18) to the resistor (28). The high-voltage terminal (22) is provided with a cover (22) which has an inner peripheral surface (50) and an inner bottom surface (52) and covers the end part of the resistor (28). The ignition coil (2) is further provided with at least one gas passage (55) connecting the inner bottom surface (52) and the outside.

Description

Technical Field

[0001] This specification discloses an ignition coil for an internal combustion engine. Background Art

[0002] A typical ignition coil includes: a primary coil and a secondary coil for generating high voltage, a resistor for reducing electrical noise, and a high-voltage terminal electrically connecting the secondary coil and the resistor. The high voltage from the secondary coil is applied to the resistor via the high-voltage terminal, and then applied to a spark plug disposed in the combustion chamber of a high-pressure internal combustion engine via the resistor. By applying this voltage, a spark caused by discharge is generated from the spark plug, and the fuel of the internal combustion engine is ignited.

[0003] The resistor is usually rod-shaped. In order to ensure the connection between the high-voltage terminal and the resistor, a high-voltage terminal having a lid-shaped connection portion with the resistor is sometimes used. An example of an ignition coil having such a high-voltage terminal is disclosed in Japanese Patent Application Laid-Open No. 2019-96788. Prior Art Documents Patent Documents

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-96788 Summary of the Invention Problems to be Solved by the Invention

[0005] In the assembly of the ignition coil, the resistor is sleeved with the lid portion of the high-voltage terminal. At this time, since air remains between the top end of the resistor and the lid portion, a relatively large force is sometimes required to insert the lid portion. This makes it difficult to install the lid portion onto the resistor and may be a main cause of damage to the top of the resistor. Therefore, an ignition coil in which the high-voltage terminal and the resistor can be easily connected is needed.

[0006] An object of the present invention is to provide an ignition coil in which a high-voltage terminal and a resistor can be easily connected. Technical Means for Solving the Problems

[0007] An ignition coil according to an embodiment includes: a primary coil, a secondary coil, a rod-shaped resistor, and a high-voltage terminal electrically connecting the output of the secondary coil and the resistor. The high-voltage terminal includes a lid having an inner peripheral surface and an internal bottom surface and covering the end of the resistor. The ignition coil further includes at least one air passage connecting the internal bottom surface and the outside. Effects of the Invention

[0008] The ignition coil has an internal bottom surface connecting the cover and an external air passage. When the cover is sleeved on the resistor, the air remaining between the top end of the resistor and the cover part is discharged to the outside through this air passage. In this ignition coil, the cover can be inserted into the resistor without applying a large force. In this ignition coil, the pressure terminal and the resistor can be easily connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a sectional view showing an ignition coil according to an embodiment. Figure 2 (a) of Figure 1 is a perspective view of the cover and the resistor of the high-voltage terminal of the ignition coil of Figure 2 (b) of Figure 2 is an exploded view of (a) of Figure 3 is a perspective view of the cover of (a) of Figure 2 showing Figure 4 (a) of Figure 3 is a sectional view taken along line IVa-IVa of Figure 4 (b) of Figure 4 is a sectional view showing the state where the resistor is inserted into the cover of (a) of Figure 5 is taken along Figure 4 line V-V of (b) of Figure 6 (a) and (b) of Figure 7 are sectional views showing the cover and the resistor of the ignition coil according to another embodiment. Figure 8 (a) of Figure 8 is a perspective view of the cover of the ignition coil according to another embodiment, Figure 8 (b) of Figure 9 is a bottom view of the cover of (a) of Figure 10 is a sectional view showing the cover and the resistor of the ignition coil according to another embodiment. Figure 11 is Figure 10 a bottom view of the cover of DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] Hereinafter, the present invention will be described in detail according to preferred embodiments with reference to appropriate drawings.

[0011] Figure 1 is a sectional view showing an ignition coil 2 according to an embodiment. InFigure 1 In Figure 1 , arrow X indicates the front of the ignition coil 2. The opposite direction is the rear. Arrow Z indicates the top of the ignition coil 2. The opposite direction is the bottom. The ignition coil 2 is used in an internal combustion engine. As Figure 1 shown, the ignition coil 2 includes a coil assembly 4, a connector portion 6, and an output portion 8. In the ignition coil 2, a filler 9 made of a thermosetting resin is further used to fill the internal gaps. In Figure 1 , a spark plug boot 10 and a spring 12 mounted on the ignition coil 2 are also shown together.

[0012] The coil assembly 4 includes a housing 14, a primary coil 16, a secondary coil 18, an iron core 20, and a high-voltage terminal 22. The primary coil 16, the secondary coil 18, the iron core 20, and the high-voltage terminal 22 are housed in the housing 14. The primary coil 16 is formed by winding a wire around the iron core 20, and the secondary coil 18 is formed by winding a wire outside the primary coil 16. The number of turns of the wire of the secondary coil 18 is much larger than that of the wire of the primary coil 16. Thus, by changing the current in the primary coil 16, a high voltage is generated in the secondary coil 18.

[0013] The high-voltage terminal 22 is electrically connected to the output terminal of the secondary coil 18 and is also electrically connected to a resistor 28 in the output portion 8 described later. The output of the secondary coil 18 is applied to the resistor 28 via the high-voltage terminal 22. The high-voltage terminal 22 includes an arm 24 and a cap 26. One end of the arm 24 is connected to the output terminal of the secondary coil 18, and the other end is connected to the cap 26. The high-voltage terminal 22 is made of a metal with excellent conductivity. Preferably, as the material of the high-voltage terminal 22, aluminum alloy and copper can be exemplified.

[0014] As Figure 1 shown, the connector portion 6 is located in front of the coil assembly 4. The connector portion 6 includes a cylindrical portion 30, external terminals 32, an igniter 34, and a housing 36. The housing 36 of the connector portion 6 is integrally formed with the housing 14 of the coil assembly 4.

[0015] The cylindrical portion 30 is in the shape of a cylinder with an open front. A plurality of external terminals 32 are located inside the cylindrical portion 30. A part of the external terminals 32 is connected to the igniter 34. The igniter 34 is located behind the cylindrical portion 30. The igniter 34 is a switch that controls the on and off of the current in the primary coil 16 according to an external signal. The housing 36 covers the periphery of the igniter 34.

[0016] As Figure 1 shown, the output terminal 8 is located below the coil assembly 4. The output portion 8 is in the shape of a cylinder extending downward from the coil assembly 4. The output portion 8 has a rod-shaped resistor 28 inside. In Figure 1In the embodiment, a spark plug boot 10 and a spring 12 are mounted on the output section 8. The high voltage generated by the secondary coil 18 is input to the resistor 28 via the high-voltage terminal 22, and then transmitted from the resistor 28 to the spring 12. When the ignition coil 2 is assembled to the engine, the spring 12 is connected to the spark plug.

[0017] Figure 2 (a) of is an enlarged perspective view of the cover 26 of the resistor 28 and the high-voltage terminal 22. Figure 2 (b) of is Figure 2 The exploded view of (a) of. The resistor 28 is rod-shaped. In this embodiment, the resistor 28 is cylindrical. The resistor 28 has an upper portion 28a, a central portion 28b, and a lower portion 28c. The outer diameters of the upper portion 28a and the lower portion 28c are slightly larger than the outer diameter of the central portion 28b. As Figure 1 shown, when the ignition coil 2 is installed on the internal combustion engine, the lower portion 28c of the resistor 28 contacts the spring 12. Although not shown, the top end of the spring 12 is connected to the spark plug. The cover 26 is sleeved on the upper portion 28a of the resistor 28. The resistor 28 has appropriate resistance value and inductance value to suppress the electrical noise (conduction noise and radiation noise) generated by the spark plug discharge.

[0018] The outer diameter size of the resistor 28 can remain unchanged from the upper end to the lower end. The shape of the resistor 28 can also not be cylindrical. For example, it can be prismatic.

[0019] As Figure 2 (a) and (b) of show, the cover 26 is cylindrical. A recess 42 is provided on the upper surface of the cover 26. As Figure 1 shown, the top end portion of the arm 24 has a downwardly protruding bent portion, and this bent portion is snapped into the recess 42 of the cover 26. Thus, the cover 26 is connected to the arm 24.

[0020] Figure 3 is a perspective view of the cover 26 observed from obliquely below. As Figure 2 (b) of and Figure 3 show, the cover 26 has a cavity 44 inside. An opening 48 of the cavity 44 is provided on the bottom surface 46 of the cover 26. Through this cavity 44, an inner peripheral surface 50 and an inner bottom surface 52 are formed on the cover 26. The inner peripheral surface 50 extends in the vertical direction (the direction in which the resistor 28 extends). The corner of the bottom surface 46 and the inner peripheral surface 50 of the cover 26 is in a rounded shape. As Figure 2 (a) of shows, the upper portion 28a of the resistor 28 is inserted into the cavity 44. The upper surface 29 of the resistor 28 contacts the inner bottom surface 52 of the cover 26. The cover 26 covers one end of the resistor 28. In this embodiment, the cover 26 covers the top portion 28a of the resistor 28. Thus, the high-voltage terminal 22 and the resistor 28 are electrically connected.

[0021] Figure 4 The (a) of Figure 3 is a cross-sectional view taken along line IVa-IVa of Figure 4 . This is a cross-section perpendicular to the extending direction of the resistor 28 in a state where the resistor 28 has not been inserted into the cavity 44. In

[0022] Figure 4 The (b) of Figure 4 is a cross-sectional view taken at a position where the resistor 28 is covered by the cover 26 in a state where the resistor 28 is inserted into the cavity 44, and is perpendicular to the extending direction of the resistor 28. In this figure, a state where the resistor 28 is inserted in the (a) of Figure 4 is shown. In this embodiment, the outer peripheral surface 53 of the resistor 28 is formed to be slightly larger than the inscribed circle Ic shown in the (a) of Figure 4 . Therefore, compared with the inner peripheral surface 50 in the (a) of Figure 4 , the inner peripheral surface 50 of the cover 26 in the (b) of Figure 4 is slightly deformed. As shown in the (b) of Figure 4 , the inner peripheral surface 50 of the cover 26 and the outer peripheral surface 53 of the resistor 28 substantially contact at a plurality of points 54. In this embodiment, the inner peripheral surface 50 of the cover 26 and the outer peripheral surface 53 of the resistor 28 contact at 3 points 54. Through this contact, the cover 26 is fixed to the resistor 28. In other words, the points 54 where the cover 26 contacts the resistor 28 are provided at positions where the cover 26 can be fixed to the resistor 28.

[0023] As Figure 4 shown in the (b) of Figure 4 , in this cross-section, there are sides on the inner peripheral surface 50 that contact the outer peripheral surface 53 of the resistor 28 and sides that do not contact the outer peripheral surface 53 of the resistor 28. Among the sides of the inner peripheral surface 50, the sides that contact the outer peripheral surface 53 of the resistor 28 are referred to as contact sides 56. Among the sides of the inner peripheral surface 50, the sides that do not contact the outer peripheral surface 53 of the resistor 28 are referred to as non-contact sides 58. In this embodiment, the number of contact sides 56 and non-contact sides 58 is 3 each. The contact sides 56 are sandwiched by two non-contact sides 58. The contact sides 56 and non-contact sides 58 are arranged alternately.

[0024] In addition, in this specification, the so-called "point contact" between the inner peripheral surface 50 of the cover 26 and the outer peripheral surface 53 of the resistor 28 means that: at the position where the inner peripheral surface 50 of the cover 26 and the outer peripheral surface 53 of the resistor 28 contact, the length of this contact portion measured along the circumferential direction of the resistor 28 is 5% or less of the outer circumference of the resistor 28.

[0025] In this embodiment, the three contact edges 56 have substantially the same length. The lengths of the three contact edges 56 may also be different. In this embodiment, the three non-contact edges 58 have substantially the same length. The lengths of the three non-contact edges 58 may also be different.

[0026] The contact edge 56 may not be sandwiched by the two non-contact edges 58. The multiple contact edges 56 may be continuous. The non-contact edge 58 may not exist. There may be multiple non-contact edges 58 between the two contact edges 56.

[0027] As described later, the number of points 54 where the inner circumferential surface 50 of the cover 26 and the outer circumferential surface 53 of the resistor 28 contact each other may not be 3. The number of points 54 where the inner circumferential surface 50 of the cover 26 and the outer circumferential surface 53 of the resistor 28 contact each other may be 3 or more and 6 or less.

[0028] Figure 5 is along Figure 4 (b) is a cross-sectional view of the VV line. Figure 5 As shown in the figure, there is a gap 55 between the inner peripheral surface 50 and the outer peripheral surface 53 at positions other than the position where the inner peripheral surface 50 and the outer peripheral surface 53 are in point contact. The gap 55 extends from the inner bottom surface 52 to the outside. When the cover 26 is put on the resistor 28, the air between the inner bottom surface 52 and the upper surface 29 of the resistor 28 is discharged to the outside through the gap 55. The gap 55 is an air passage 55 connecting the inner bottom surface 52 and the outside. In this embodiment, since the inner peripheral surface 50 and the outer peripheral surface 53 are in contact at three points 54, three air passages 55 are formed between these points 54.

[0029] The effects of this embodiment will be described below.

[0030] In the ignition coil 2, a gap 55 is provided between the inner peripheral surface 50 of the cover 26 and the outer peripheral surface 53 of the resistor 28. When the cover 26 is put on the resistor 28, the air remaining between the upper surface 29 of the resistor 28 and the inner bottom surface 52 of the cover 26 is discharged to the outside from the gap 55. The gap 55 is an air passage 55 connecting the inner bottom surface 52 of the cover 26 and the outside. In the ignition coil 2, the cover 26 can be inserted into the resistor 28 without applying a large force. In the ignition coil 2, the high voltage terminal 22 and the resistor 28 can be easily connected. When the cover 26 is put on the resistor 28, the upper part 28a of the resistor 28 is prevented from being damaged.

[0031] Generally, there are deviations in the size and shape of the outer diameter of resistors in each product. For example, in a cylindrical resistor, its outer diameter shape may deviate from a perfect circle. Due to this deviation, it is sometimes difficult to mount the cap on the resistor. In some cases, the cap cannot be sleeved onto the specified position of the resistor, and the upper part of the resistor may be damaged. An ignition coil is needed in which the high-voltage terminal and the resistor can be easily and reliably connected.

[0032] In this ignition coil 2, in a cross-section perpendicular to the direction in which the resistor 28 extends, the outer peripheral surface 53 of the resistor 28 and the inner peripheral surface 50 of the cap 26 of the high-voltage terminal 22 are in contact at three points 54. Since the outer peripheral surface 53 of the resistor 28 and the inner peripheral surface 50 of the cap 26 of the high-voltage terminal 22 are in point contact, the contact area between the resistor 28 and the cap 26 is small. In addition, since the outer peripheral surface 53 of the resistor 28 and the inner peripheral surface 50 of the cap 26 of the high-voltage terminal 22 are in point contact, even if there are deviations in the outer diameter or shape of the resistor 28, the area of the deformable part of the inner peripheral surface 50 is small. The inner peripheral surface 50 of the cap 26 can deform softly. Even if there are deviations in the outer diameter or shape of the resistor 28, in this ignition coil 2, the high-voltage terminal 22 and the resistor 28 can be easily connected. Furthermore, since the inner peripheral surface 50 of the cap 26 is in contact with the resistor 28 at three points 54, the cap 26 can be stably fixed to the resistor 28. In this ignition coil 2, the high-voltage terminal 22 and the resistor 28 can be reliably connected.

[0033] In this embodiment, the inner peripheral surface 50 has a contact edge 56 and a non-contact edge 58. Compared with the case where the inner peripheral surface 50 only has a contact edge 56, the peripheral surface 50 can be made into a shape closer to a circle. Thereby, the deviation in the thickness between the inner peripheral surface 50 and the outer peripheral surface of the cap 26 due to different positions can be reduced. This helps to achieve excellent strength of the cap 26.

[0034] In this embodiment, the contact edge 56 is sandwiched by the non-contact edge 58. The non-contact edges 58 exist on both sides of the contact edge 56. In this way, when the resistor 28 comes into contact with the contact edge 56, the inner peripheral surface 50 of the cap 26 can deform softly. In this ignition coil 2, the high-voltage terminal 22 and the resistor 28 can be easily connected.

[0035] As Figure 4 shown in (a) and (b) of, in this embodiment, the corner between the contact edge 56 and the non-contact edge 58 has a rounded shape. Figure 4The symbol C in (a) indicates the intersection position of the contact edge 56 and the non-contact edge 58 when the contact edge 56 and the non-contact edge 58 are extended without the rounded corner. When the corners of the contact edge 56 and the non-contact edge 58 do not have rounded corners, the corners of the contact edge 56 and the non-contact edge 58 become the intersection positions. In this specification, the lengths of the contact edge 56 and the non-contact edge 58 are defined as the distances between two intersection positions C located at both ends of the edge. The double arrow L1 represents the length of the contact edge 56. The double arrow L2 represents the length of the non-contact edge 58 adjacent to the contact edge 56.

[0036] Preferably, the length L1 of the contact edge 56 is greater than the length L2 of the non-contact edge 58 adjacent to the contact edge 56. By making the length L1 greater than the length L2, when the resistor 28 contacts the contact edge 56, the inner peripheral surface 50 of the cover 26 can be deformed softly. In this ignition coil 2, the high-voltage terminal 22 and the resistor 28 can be easily connected. From this viewpoint, it is more preferable that the length of each contact edge 56 is greater than the lengths of all other non-contact edges 58.

[0037] Preferably, the length L1 is 1.5 times or more the length L2. By making the length L1 1.5 times or more the length L2, when the resistor 28 contacts the contact edge 56, the inner peripheral surface 50 of the cover 26 can be deformed softly. In this ignition coil 2, the high-voltage terminal 22 and the resistor 28 can be easily connected. Preferably, the length L1 is 2.5 times or less the length L2. By making the length L1 2.5 times or less the length L2, the inner peripheral surface 50 can be made into a shape close to a circle. Thereby, the deviation in the thickness between the inner peripheral surface 50 and the outer peripheral surface 53 of the cover 26 due to different positions can be reduced. This contributes to achieving excellent strength of the cover 26.

[0038] Figure 6 (a) is a cross-sectional view of the cover 60 of the high-voltage terminal and the resistor 62 of the ignition coil showing another embodiment. This is a cross-section perpendicular to the extending direction of the resistor 62 at the position where the resistor 62 is covered by the cover 60. This ignition coil is the same as the Figure 1 ignition coil 2 except for the cover 60.

[0039] As Figure 6 shown in (a), in this embodiment, the inner peripheral surface 64 of the cover 60 has a substantially octagonal shape. In this embodiment, the inner peripheral surface 64 is composed of eight sides. As Figure 6As shown in (a) of FIG. , the inner peripheral surface 64 of the cover 60 and the outer peripheral surface 66 of the resistor 62 are in contact at a plurality of points 68. In this embodiment, the inner peripheral surface 64 of the cover 60 and the outer peripheral surface 66 of the resistor 62 are in contact at four points 68. Through this contact, the cover 60 is fixed to the resistor 62. In this embodiment, the number of contact sides 70 and non-contact sides 72 is 4 respectively. The contact side 70 is sandwiched by two non-contact sides 72. The contact side 70 and the non-contact side 72 are arranged alternately. There is a gap 67 between the inner peripheral surface 64 and the outer peripheral surface 66. This gap 67 is an air passage connecting the inner bottom surface of the cover 60 and the outside.

[0040] In this ignition coil, a gap 67 is provided between the inner peripheral surface 64 of the cover 60 and the outer peripheral surface 66 of the resistor 62. When the cover 60 is sleeved on the resistor 62, the air remaining between the upper surface of the resistor 62 and the inner bottom surface 52 of the cover 60 is discharged to the outside through this gap 67. In this ignition coil, the cover 60 can be inserted into the resistor 62 without applying a large force. In this ignition coil, the high-voltage terminal can be easily connected to the resistor 62. It is possible to prevent the upper part of the resistor 62 from being damaged when the cover 60 is sleeved on the resistor 62.

[0041] In this ignition coil, in a cross-section perpendicular to the direction in which the resistor 62 extends, the outer peripheral surface 66 of the resistor 62 and the inner peripheral surface 64 of the cover 60 of the high-voltage terminal are in contact at four points 68. Since the outer peripheral surface 66 of the resistor 62 and the inner peripheral surface 64 of the cover 60 of the high-voltage terminal are in point contact, the contact area between the resistor 62 and the cover 60 is small. In addition, since the outer peripheral surface 66 of the resistor 62 and the inner peripheral surface 64 of the cover 60 of the high-voltage terminal are in point contact, the inner peripheral surface 64 of the cover 60 can be deformed softly. Even if there are deviations in the outer diameter or shape of the resistor 62, in this ignition coil, the high-voltage terminal and the resistor 62 can be easily connected. In addition, since the inner peripheral surface 64 of the cover 60 is in contact with the resistor 62 at four points 68, the cover 60 can be stably fixed to the resistor 62. In this ignition coil, the high-voltage terminal and the resistor 62 can be reliably connected.

[0042] Figure 6 FIG. (b) is a cross-sectional view showing the cover 80 of the high-voltage terminal and the resistor 82 of an ignition coil according to another embodiment. This is a cross-section perpendicular to the extending direction of the resistor 82 at the position covered by the cover 80 of the resistor 82. This ignition coil is the same as the ignition coil 2 except for the cover 80. Figure 1 of FIG.

[0043] As shown in Figure 6 FIG. (b), in this embodiment, the inner peripheral surface 84 of the cover 80 is in a substantially dodecagonal shape. In this embodiment, the inner peripheral surface 84 is composed of twelve sides. As shown in Figure 6As shown in FIG. (b), in this embodiment, the inner peripheral surface 84 of the cover 80 and the outer peripheral surface 86 of the resistor 82 are in contact at six points 88. By this contact, the cover 80 is fixed to the resistor 82. In this embodiment, the number of contact sides 90 and non-contact sides 92 is 6 respectively. The contact side 90 is sandwiched by two non-contact sides 92. The contact sides 90 and non-contact sides 92 are arranged alternately. There is a gap 87 between the inner peripheral surface 84 and the outer peripheral surface 86. This gap 87 is an air passage connecting the inner bottom surface of the cover 80 and the outside.

[0044] Although not shown, in the ignition coil of another other embodiment, the inner peripheral surface has a substantially decagonal shape. In this embodiment, the inner peripheral surface is composed of ten sides. In this embodiment, the inner peripheral surface of the cover and the outer peripheral surface of the resistor are in contact at 5 points. By this contact, the cover is fixed to the resistor. In this embodiment, the number of contact sides and non-contact sides is 5 respectively. The contact side is sandwiched by two non-contact sides. The contact sides and non-contact sides are arranged alternately. There is a gap between the inner peripheral surface and the outer peripheral surface. This gap is an air passage connecting the inner bottom surface of the cover and the outside.

[0045] Figure 7 is a cross-sectional view of the cover 100 and the resistor 102 of the high-voltage terminal of the ignition coil of another other embodiment. This is a cross-section perpendicular to the extending direction of the resistor 102 at the position covered by the cover 100 of the resistor 102. This ignition coil is the same as the Figure 1 ignition coil 2 except for the cover 100.

[0046] As Figure 7 shown, in this embodiment, the inner peripheral surface 104 of the cover 100 and the outer peripheral surface 106 of the resistor 102 are in contact at 3 points 108. In this embodiment, the number of contact sides 110 and non-contact sides 112 is 3 respectively. The contact side 110 is sandwiched by two non-contact sides 112. The contact sides 110 and non-contact sides 112 are arranged alternately. There is a gap 107 between the inner peripheral surface 104 and the outer peripheral surface 106. As Figure 7 shown, in this embodiment, the non-contact side 112 is curved. The non-contact side 112 is in an arc shape.

[0047] In this ignition coil, in a cross-section perpendicular to the direction in which the resistor 102 extends, the outer peripheral surface 106 of the resistor 102 and the inner peripheral surface 104 of the cover 100 of the high-voltage terminal are in contact at three points 108. Further, in the present embodiment, since the non-contact edge 112 is arc-shaped, the thickness between the outer peripheral surface 106 and the inner peripheral surface 104 of the cover 100 at this portion can be reduced. As a result, the inner peripheral surface 104 of the cover 100 can be deformed softly. Even if there are deviations in the outer diameter or shape of the resistor 102, in this ignition coil, the high-voltage terminal and the resistor 102 can be easily connected. Further, since the inner peripheral surface 104 of the cover 100 is in contact with the resistor 102 at three points 108, the cover 100 can be stably fixed to the resistor 102. In this ignition coil, the high-voltage terminal and the resistor 102 can be reliably connected.

[0048] The shape of the cover of the ignition coil is not limited to the shape of the above-described embodiment. For example, the contact edge may be curved. It is sufficient that the outer peripheral surface of the resistor and the inner peripheral surface of the cover of the high-voltage terminal are in contact at 3 or more and 6 or less points.

[0049] From the viewpoint that the high-voltage terminal and the resistor can be more easily connected, the number of points at which the outer peripheral surface of the resistor and the inner peripheral surface of the cover of the high-voltage terminal are in contact is more preferably 5 or less, further preferably 4 or less, and most preferably 3.

[0050] Figure 8 (a) is a perspective view of the cover 120 of the high-voltage terminal of the ignition coil according to another other embodiment as viewed obliquely from below. Figure 8 (b) is Figure 8 the bottom view of the cover 120 of (a). This ignition coil is the same as the ignition coil 2 shown in Figure 1 except for the cover 120.

[0051] As Figure 8 (a) shows, the cover 120 has a cavity 122 inside. Through this cavity 122, an inner peripheral surface 124 and an inner bottom surface 126 are formed on the cover 120. The inner peripheral surface 124 extends in the vertical direction (the direction in which the resistor extends). As Figure 8 (a) shows, a groove 128 is provided on the inner peripheral surface 124 of the cover 120. When viewed from below, except for the groove 128, the inner peripheral surface 124 is substantially circular. The upper part of the resistor is inserted into this cavity 122. At this time, the inner peripheral surface 124 is in contact with the outer peripheral surface of the resistor. The cover 120 covers one end of the resistor. As a result, the high-voltage terminal and the resistor are electrically connected.

[0052] As Figure 8 (a) shows, in this embodiment, three grooves 128 are provided on the inner peripheral surface 124. As Figure 8As shown in (b) thereof, these three slots 128 are substantially equally spaced. Each slot 128 extends from the end on the inner bottom surface 126 side to the end on the bottom surface 130 side. When the cover 120 is sleeved on the resistor, the air between the inner bottom surface 126 and the upper surface of the resistor is discharged through the slot 128. The slot 128 is an air passage 128 connecting the inner bottom surface 126 and the outside.

[0053] In this ignition coil, a slot 128 connecting the inner bottom surface 126 of the cover 120 and the outside is provided. When the cover 120 is sleeved on the resistor, the air remaining between the upper surface of the resistor and the inner bottom surface 126 of the cover 120 is discharged from the slot 128. In this ignition coil, the cover 120 can be inserted into the resistor without applying a large force. In this ignition coil, the high-voltage terminal and the resistor can be easily connected. Breakage of the upper part of the resistor is prevented when the cover 120 is sleeved on the resistor.

[0054] In Figure 8 In (b), the double arrow W represents the width of the slot 128. From the viewpoint of effectively discharging the air between the inner bottom surface 126 and the upper surface of the resistor when the cover 120 is sleeved on the resistor, the width W is preferably 0.5 mm or more, more preferably 1.0 mm or more, and further preferably 2.0 mm or more. From the viewpoint of easy processing, the width W is preferably 5 mm or less.

[0055] In Figure 8 In (b), the double arrow D represents the depth of the slot 128. From the viewpoint of effectively discharging the air between the inner bottom surface 126 and the upper surface of the resistor when the cover 120 is sleeved on the resistor, the depth D is preferably 0.5 mm or more, more preferably 1.0 mm or more, and further preferably 1.2 mm or more. From the viewpoint of easy processing, the depth D is preferably 3 mm or less.

[0056] Preferably, the three slots 128 are equally spaced. By doing so, when the cover 120 is sleeved on the resistor, the air between the inner bottom surface 126 and the upper surface of the resistor can be evenly discharged from the respective slots 128. In this ignition coil, the high-voltage terminal and the resistor can be easily connected.

[0057] Figure 9 is a bottom view of the cover 140 of the high-voltage terminal of the ignition coil showing another other embodiment. In this ignition coil, slots 144 are provided on the inner peripheral surface 142 of the cover 140. In this embodiment, two slots 144 are provided. This ignition coil is the same as the ignition coil shown in Figure 8 except for the number of slots 144.

[0058] In this embodiment, two slots 144 are provided at opposite positions. By doing so, when the cover 140 is sleeved on the resistor, the air between the inner bottom surface 146 and the upper surface of the resistor can be uniformly discharged from the respective slots 144. In this ignition coil, the high-voltage terminal and the resistor can be easily connected.

[0059] The number of the slots 144 can be more than 4 or 1. From the viewpoint of effectively discharging the air remaining between the upper surface of the resistor and the inner bottom surface 146 of the cover 140, the number of the slots 144 is preferably 2 or more. From the viewpoint of ease of processing, the number of the slots 144 is preferably 6 or less, more preferably 5 or less, and further preferably 4 or less.

[0060] Figure 10 is a cross-sectional view of the cover 150 and the resistor 152 of the high-voltage terminal of the ignition coil according to another other embodiment, and Figure 10 shows a cross-section taken along a plane parallel to the direction in which the high-voltage terminal extends. Figure 11 is shown Figure 10 is a bottom view of the cover 150. This ignition coil is the same as the ignition coil 2 shown in Figure 1 except for the cover 150.

[0061] As Figure 10 shown, the cover 150 has a hole 158 extending from the inner bottom surface 154 to the top surface 156. As Figure 10 shown, in this embodiment, one opening of the hole 158 is located at the bottom of the recess 160 on the upper surface 156. As Figure 11 shown, the other opening of the hole 158 is provided at the center of the inner bottom surface 154. When viewed from below, the inner peripheral surface 155 of the cover 150 is substantially circular. The inner peripheral surface 155 contacts the outer peripheral surface of the resistor. When the cover 150 is sleeved on the resistor 152, the air between the inner bottom surface 154 and the upper surface 162 of the resistor 152 is discharged through the hole 158. The hole 158 is an air passage connecting the inner bottom surface 154 and the outside.

[0062] In this ignition coil, a hole 158 connecting the inner bottom surface 154 of the cover 150 and the outside is provided. When the cover 150 is sleeved on the resistor 152, the air remaining between the upper surface 162 of the resistor 152 and the inner bottom surface 154 of the cover 150 is discharged to the outside through the hole 158. In this ignition coil, the cover 150 can be inserted into the resistor 152 without applying a large force. In this ignition coil, the high-voltage terminal and the resistor 152 can be easily connected. It is possible to prevent the upper part of the resistor 152 from being damaged when the cover 150 is sleeved on the resistor 152.

[0063] The opening of the hole 158 is preferably provided at the center of the inner bottom surface 154. In this way, when the cover 150 is sleeved on the resistor 152, the air between the inner bottom surface 154 and the upper surface 162 of the resistor 152 can be evenly discharged from the hole 158. In this ignition coil, the high-voltage terminal and the resistor 152 can be easily connected.

[0064] In Figure 11 it, the double arrow E represents the inner diameter of the hole 158. The inner diameter E is preferably 0.5 mm or more. By making the inner diameter E 0.5 mm or more, the air remaining between the upper surface 162 of the resistor 152 and the inner bottom surface 154 of the cover 150 is effectively discharged to the outside from the hole 158. From this viewpoint, the inner diameter E is more preferably 1.0 mm or more.

[0065] As Figure 1 shown in, the bent portion of the arm enters the recess 160 on the upper surface 156 of the cover 150. By the surface contact between the bent portion and the recess 160, a good contact area between the arm and the cover 150 is ensured. When the inner diameter E of the hole 158 exceeds 2.0 mm, the corner of the bent portion easily enters the opening of the hole 158, and this contact area may become smaller. From the viewpoint of ensuring a good contact area between the arm and the cover 150, the inner diameter E is preferably 2.0 mm or less.

[0066] In the above, as an embodiment of the ignition coil having an air passage, an ignition coil in which the outer peripheral surface of the resistor is in point contact with the inner peripheral surface of the cover, an ignition coil in which the inner peripheral surface of the cover has a groove, and an ignition coil in which the cover has a hole extending from the inner bottom surface to the upper surface are described. The ignition coil may also have a plurality of these features. For example, in another embodiment of the ignition coil, the outer peripheral surface of the resistor and the inner peripheral surface of the cover may be in point contact, and the cover may have a hole extending from the inner bottom surface to the upper surface. In another embodiment of the ignition coil, the inner peripheral surface of the cover may have a groove, and the cover may have a hole extending from the inner bottom surface to the upper surface.

[0067] As described above, in this embodiment, an ignition coil in which the high-voltage terminal and the resistor can be easily connected is obtained. Thus, the superiority of this embodiment is obvious.

[0068] [Disclosed Items] The following items are disclosures of preferred embodiments.

[0069] [Item 1] An ignition coil for an internal combustion engine, comprising: a primary coil, a secondary coil, a rod-shaped resistor, and a high-voltage terminal that electrically connects the output of the secondary coil to the resistor, the high-voltage terminal includes a cover having an inner peripheral surface and an inner bottom surface and covering an end of the resistor, The ignition coil further includes at least one air passage connecting the inner bottom surface and the outside.

[0070] [Item 2] For the ignition coil according to Item 1, in a cross-section perpendicular to the extending direction of the resistor at the position covered by the cover, the outer peripheral surface of the resistor contacts the inner peripheral surface at three or more and six or less points. One of the air passages is a gap between the outer peripheral surface and the inner peripheral surface.

[0071] [Item 3] For the ignition coil according to Item 2, in the cross-section, the outer peripheral surface of the resistor contacts the inner peripheral surface of the cover at three points.

[0072] [Item 4] For the ignition coil according to Item 2 or 3, in the cross-section, the inner peripheral surface has a plurality of contact edges that are in point contact with the resistor and a plurality of non-contact edges that are not in contact with the resistor, and each contact edge is sandwiched by two non-contact edges.

[0073] [Item 5] For the ignition coil according to Item 4, the length of each contact edge is longer than the length of the adjacent non-contact edge.

[0074] [Item 6] For the ignition coil according to Item 5, the length of each contact edge is 1.5 times or more and 2.5 times or less the length of the adjacent non-contact edge.

[0075] [Item 7] For the ignition coil according to any one of Items 2 to 6, in the cross-section, the inner peripheral surface of the resistor is polygonal.

[0076] [Item 8] For the ignition coil according to any one of Items 1 to 7, a groove extending from the end on the inner bottom surface side is provided on the inner peripheral surface, and one of the air passages is the groove.

[0077] [Item 9] For the ignition coil according to Item 8, the number of the grooves is two, and one groove and the other groove are provided at opposite positions.

[0078] [Item 10] For the ignition coil according to Item 8, the number of the grooves is three, and these grooves are provided at equal intervals.

[0079] [Item 11] The ignition coil according to any one of Items 1 to 10, wherein the cover has a hole extending from the inner bottom surface to the upper surface of the cover, and one of the air passages is the hole.

[0080] [Item 12] The ignition coil according to Item 11, wherein the opening of the hole is located at the center of the bottom surface.

[0081] [Item 13] The ignition coil according to Item 11 or 12, wherein the inner diameter of the hole is 0.5 mm or more and 2.0 mm or less. Industrial applicability

[0082] The ignition coil described above is used in various internal combustion engines. Symbol description

[0083] 2... Ignition coil 4... Coil assembly 6... Connector part 8... Output part 10... Spark plug boot 12... Spring 14, 36... Housing 16... Primary coil 18... Secondary coil 20... Iron core 22... High-voltage terminal 24... Arm 26, 60, 80, 100, 120, 140, 150... Covers of high-voltage terminals 28, 62, 82, 102, 152... Resistors 29, 162... Upper surfaces of resistors 30... Cylindrical part 32... External terminal 34... Igniter 42, 160... Depressions 44, 122... Cavities 46, 130... Bottom surfaces 48... Opening 50, 64, 84, 104, 124, 142, 155... Inner peripheral surfaces of the cover 52, 126, 146, 154... Inner bottom surfaces of the cover 53, 66, 86, 106... Outer peripheral surfaces of the resistors 54, 68, 88, 108... Contact points 55, 67, 87, 107... Clearances (air passages) 56, 70, 90, 110... Contact edges 58, 72, 92, 112... non-contact edges 128, 144... grooves (air channels) 156... upper surface of the cover 158... holes

Claims

1. An ignition coil for an internal combustion engine, characterized in that, the ignition coil includes: a primary coil, a secondary coil, a rod-shaped resistor, and a high-voltage terminal that electrically connects the output of the secondary coil to the resistor, the high-voltage terminal includes a cover having an inner peripheral surface and an inner bottom surface and covering the end of the resistor, the ignition coil further includes at least one air passage connecting the inner bottom surface and the outside.

2. The ignition coil according to claim 1, characterized in that, in a cross-section perpendicular to the direction in which the resistor extends at a position covered by the cover, the outer peripheral surface of the resistor contacts the inner peripheral surface at more than 3 and less than 6 points, one of the air passages is a gap between the outer peripheral surface and the inner peripheral surface.

3. The ignition coil according to claim 2, characterized in that, in the cross-section, the outer peripheral surface of the resistor and the inner peripheral surface of the cover contact at 3 points.

4. The ignition coil according to claim 2 or 3, characterized in that, in the cross-section, the inner peripheral surface has a plurality of contact edges that contact the resistor at points and a plurality of non-contact edges that do not contact the resistor, and each contact edge is sandwiched by two non-contact edges.

5. The ignition coil according to claim 4, characterized in that, the length of each contact edge is longer than the length of the adjacent non-contact edge.

6. The ignition coil according to claim 5, characterized in that, the length of each contact edge is 1.5 times or more and 2.5 times or less the length of the adjacent non-contact edge.

7. The ignition coil according to any one of claims 2 to 6, characterized in that, in the cross-section, the inner peripheral surface of the resistor is polygonal.

8. The ignition coil according to any one of claims 1 to 7, characterized in that, a groove extending from the end on the inner bottom surface side is provided on the inner peripheral surface, and one of the air passages is the groove.

9. The ignition coil according to claim 8, characterized in that, the number of the grooves is 2, and one groove and the other groove are arranged at opposite positions.

10. The ignition coil according to claim 8, characterized in that, the number of the grooves is 3, and these grooves are arranged at equal intervals.

11. The ignition coil according to any one of claims 1 to 10, characterized in that, the cover has a hole extending from the inner bottom surface to the upper surface of the cover, and one of the air passages is the hole.

12. The ignition coil according to claim 11, characterized in that, the opening of the hole is located at the center of the bottom surface.

13. The ignition coil according to claim 11 or 12, characterized in that, the inner diameter of the hole is 0.5 mm or more and 2.0 mm or less.

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