Ignition coil
The ignition coil with ribbed connecting parts addresses axial misalignment and wear issues in compact designs by enhancing stiffness and alignment, ensuring reliable installation and performance in curved spark plug holes.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-05
- Publication Date
- 2026-03-12
AI Technical Summary
Existing ignition coils face challenges in compact designs for curved spark plug holes, leading to axial misalignment and wear due to compressive forces and vibrations, which affect mountability and resistance voltage.
The ignition coil features a tubular connecting part with first and second ribs on its outer surface, designed to guide insertion and enhance stiffness, ensuring axial alignment and preventing wear by maintaining a larger diameter at the proximal end.
The design suppresses axial misalignment and wear, improving mountability and maintaining resistance voltage by guiding the coil through curved spark plug holes effectively.
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Abstract
Description
[CROSS-REFERENCE TO A SIMILAR REGISTRATION]
[0001] The present application is based on the Japanese patent application No. JP 2023-081022 A, filed on May 16, 2023, the contents of which are incorporated into the present application by reference. [TECHNICAL FIELD]
[0002] The present disclosure relates to ignition coils for use in ignition devices of internal combustion engines. [STATE OF THE ART]
[0003] Ignition devices provided in internal combustion engines generally include an ignition coil to apply a high voltage to a spark plug facing a combustion chamber. In recent years, high-efficiency internal combustion engines have needed to be more compact to improve fuel efficiency. Furthermore, the internal structures of cylinder heads for which ignition devices are provided have become increasingly complex, and there are increasing limitations on the cylinder head components where ignition devices are mounted. Therefore, research has been conducted to design spark plug holes, in which spark plugs are placed, in a curved shape, thereby making the mounting structures of ignition coils more compact.
[0004] In this case, it is necessary to design connecting parts of ignition coils attached to spark plugs with flexible, one-piece molded parts, for example made of rubber, and to mount the connecting parts in a bent state within the spark plug holes. For example, patent specification 1 discloses an ignition coil device for an internal combustion engine that includes a cylindrical connector socket serving as a connecting part. A thin-walled section is formed in the electrically insulating and flexible connector socket, which faces a bend in the spark plug hole. The thin-walled section can be easily bent when a spark plug is inserted into the centrally bent, constant-diameter spark plug hole in the spark plug boot.Furthermore, a radially projecting protective part is provided at a distal end of the plug sleeve to facilitate the alignment of the central axes of the plug sleeve and the spark plug, thereby improving insertion. [LITERATURE ON THE STATE OF THE ART][PATENT LITERATURE]
[0005] Patent Document 1: JP 4267042 B2 [SUMMARY OF THE INVENTION]
[0006] When installing an ignition device in a curved spark plug hole, it is necessary to insert a tool into the hole. Therefore, in practice, it is difficult to maintain a constant spark plug hole diameter, as disclosed in Patent Document 1; and the inner diameter of the spark plug hole on the entry side of the curve is generally larger than that on the spark plug side. In this case, if the entire connecting part is made of an elastic material, local compression or deflection is likely to occur due to the compressive force exerted during spark plug insertion. Consequently, it is difficult to install the connecting part while simultaneously preventing axial misalignment at the curve of the spark plug hole, both on its distal and proximal sides.Furthermore, in the case of the form of the connecting part with a thin wall section, as disclosed in patent document 1, if the thin wall section is brought into contact with the bend of the spark plug hole, for example by axial misalignment, wear due to vibration or the like may occur after the ignition coil has been mounted on an engine; thus the resistance voltage of the ignition coil may be reduced.
[0007] One objective of the present disclosure is to provide an ignition coil which, when mounted in a bent spark plug hole, can suppress axial misalignment while maintaining the insertability of a connecting part, thereby improving mountability and wear resistance.
[0008] According to the present disclosure, an ignition coil is provided which is configured to supply a high voltage to a spark plug which is arranged in a spark plug hole with a bend, the ignition coil comprising the following: a coil main body part configured to be arranged on a proximal-side inlet part of the spark plug hole, the proximal-side inlet part having an inner diameter larger than that of the bend; and a connecting part formed from a tubular elastic body which is bendable and deformable, wherein the connecting part has a proximal end which is attached to the coil main body part and a distal end which is to be attached to the spark plug, where: the connecting part has a plurality of first ribs formed on an outer circumferential surface or outer circumferential surface of a tubular main section of the connecting part, each of the first ribs extending along an axis of the connecting part, the tubular main section having a portion of it opposite the bend of the spark plug hole; the connecting part further comprises a plurality of second ribs formed on an outer circumferential surface of a proximal tubular section of the connecting part, each of the second ribs also extending along the axis of the connecting part, the proximal tubular section being located on a proximal side of the main tubular section; and Along the axis of the connecting part, a maximum value d1 of a first rib diameter, represented by the diameter of an imaginary circumscribing circle with its center on the axis and circumscribing tips of the first ribs, and a maximum value d2 of a second rib diameter, represented by the diameter of an imaginary circumscribing circle with its center on the axis and circumscribing tips of the second ribs, satisfy the relationship d2 > d1.
[0009] In the aforementioned configuration of the ignition coil according to the present disclosure, the stiffness of the connecting part is improved by the first ribs formed on the tubular main section of the connecting part and the second ribs formed on the proximal tubular section of the connecting part. Furthermore, the first and second ribs, each extending along the axis of the connecting part, act as guides, improving the insertion of the connecting part into the spark plug hole. Consequently, the tubular main section can be bent and deformed along the shape of the curved spark plug hole while suppressing axial misalignment; and the first ribs are arranged at a location facing the bend of the spark plug hole and coaxial with the spark plug hole.Furthermore, on the side of the proximal inlet section, whose inner diameter is larger than that of the bend, a proximal tubular section is arranged on which the second ribs are formed, the maximum diameter of which is larger than that of the first ribs. Consequently, it becomes possible to suppress axial misalignment during the insertion of the connecting part into the spark plug hole and displacement due to vibration or the like, thereby preventing a deterioration of properties due to wear.
[0010] In summary, according to the present disclosure, it will be possible to provide the ignition coil which, when mounted in the curved spark plug hole, can suppress axial misalignment while maintaining the insertability of the connecting part, thereby improving mountability and wear resistance. [BRIEF DESCRIPTION OF THE DRAWINGS]
[0011] The above-described task, other tasks, features and advantageous benefits according to the present disclosure will become clear from the following detailed explanation with reference to the accompanying drawings.
[0012] It shows / shows: Fig. 1 A partially cut-away front view of an ignition device with an ignition coil in an assembled state according to a first embodiment. Fig. 2 a partially cutaway front view of the ignition device, illustrating an assembly process of the ignition coil according to the first embodiment. Fig. 3 a front view of the ignition coil according to the first embodiment. Fig. 4 Cross-sectional views of the ignition coil according to the first embodiment, i.e. a cross-sectional view along line II in Fig. 3 and a cross-sectional view along line II-II in Fig. 3; Fig. 5 Cross-sectional views of the ignition coil according to the first embodiment, i.e. a cross-sectional view along line III-III in Fig. 3 and a cross-sectional view along line IV-IV in Fig. 3; Fig. 6 a longitudinal section view showing part of the ignition coil according to the first embodiment. Fig. 7 a diagram illustrating an assembly process of an ignition coil according to a first comparative example. Fig. 8 Another diagram illustrating the assembly process of the ignition coil according to the first comparative example; and Fig. 9 a cross-sectional view illustrating an assembled state of an ignition coil according to a second comparative example. [FORMS OF THE INVENTION][First embodiment]
[0013] With reference to the Fig. Sections 1 to 6 will describe an embodiment that forms an ignition coil according to the present disclosure. As in Fig. As shown in Figure 1, an ignition coil 1 is electrically connected to a spark plug P, which is provided in an internal combustion engine such as a vehicle engine, and is used to supply a high voltage to the spark plug P. The spark plug P is located in a spark plug hole H, which has a bend H1. The ignition coil 1 comprises a coil main body part 11, which is located at a proximal-side input part H2 of the spark plug hole H, and a connecting part 2.
[0014] The spark plug hole H, formed in a cylinder head E1, has a curved shape, with the bend H1 located in the center. The proximal inlet section H2 of the spark plug hole H has an inner diameter larger than that of the bend H1. The connecting section 2 is made of a tubular elastic body that is flexible and deformable. Within the spark plug hole H, the connecting section 2 is attached at its proximal end to the coil body section 11 and at its distal end to the spark plug P.
[0015] The proximal side is the spark plug hole entry side when the connecting part 2 is inserted into the spark plug hole H and mounted on the spark plug P in the extension direction of the curved spark plug hole H, as shown in Fig. Figure 2 shows the side on which the coil body part 11 is located. The distal side is the side opposite the proximal side and is the side on which the spark plug P is located. In the case of the curved spark plug hole H, the axis L2 on the proximal side of the bend H1 does not coincide with the axis L1 on the distal side of the bend H1; therefore, the direction of extension of the spark plug hole H also changes, which is the direction along the axes L1 and L2.
[0016] In the Fig. In the assembled state shown in Figure 1, the connecting part 2 has a tubular main section 21, which includes a section facing the bend H1 of the spark plug hole H, and a proximal tubular section 22 located on the proximal side of the tubular main section 21. As shown in Figure 1, the connecting part 2 has a tubular main section 21 which includes a section facing the bend H1 of the spark plug hole H and a proximal tubular section 22 located on the proximal side of the tubular main section 21. Fig. As shown in Figure 3, a plurality of first ribs 31 are formed on an outer circumferential surface of the tubular main section 21, each extending along the axis L of the connecting part 2. Conversely, a plurality of second ribs 32 are formed on an outer circumferential surface of the proximal tubular section 22, each extending along the axis L of the connecting part 2. The first ribs 31 and the second ribs 32 each project in a direction perpendicular to the axis L, i.e., they project outwards in a radial direction X of the connecting part 2.
[0017] Furthermore, as in Fig. As shown in Figure 4, when viewed in a direction along the axis L, a first rib diameter in the tubular main section 21 is represented by the diameter of an imaginary circumscribing circle C1, whose center c1 lies on the axis of the tubular main section 21 and circumscribes the tips of the first ribs 31; and a second rib diameter in the proximal tubular section 22 is represented by the diameter of an imaginary circumscribing circle C2, whose center c2 lies on the axis of the proximal tubular section 22 and circumscribes the tips of the second ribs 32. Furthermore, the maximum value d1 of the first rib diameter and the maximum value d2 of the second rib diameter satisfy the relationship d2 > d1.This means that the connecting part 2 is configured such that the maximum outer diameter of the proximal tubular section 22 is larger than the maximum outer diameter of the tubular main section 21.
[0018] In the configuration described above, the first ribs 31 and the second ribs 32 act as guides when the connecting part 2 of the ignition coil 1 is inserted into the curved spark plug hole H, thus improving its ease of insertion. Furthermore, the first ribs 31 and the second ribs 32 enhance the rigidity of the connecting part 2 of the ignition coil 1, enabling the ignition coil 1 to be mounted in the spark plug hole H while suppressing axial misalignment. Additionally, the first ribs 31 are positioned to face the bend H1 of the spark plug hole H, while the second ribs 32, whose maximum outer diameter is larger than that of the first ribs 31, are located on the inlet side of the spark plug hole, where the inner diameter of the spark plug hole H is larger than that at the bend H1.
[0019] In particular, the first ribs 31 can be arranged continuously on both the distal and proximal sides of the section of the connecting part 2 facing the bend H1 of the spark plug hole H. In this case, the first ribs 31 straddle the bend H1 of the spark plug hole H when the tubular main section 21, which includes the first ribs 31, is bent and deformed according to the curved shape of the spark plug hole H, thereby amplifying the effects of suppressing axial misalignment during insertion of the connecting part 2 into the spark plug hole H and displacement due to vibration or the like.
[0020] On the other hand, the second ribs 32 can be arranged continuously from the proximal side to the distal side and face a proximal end portion of the spark plug hole H, which includes the proximal inlet portion H2. As a result, the axial stiffness of the connecting part 2 on the proximal side is improved, thereby enhancing the effects of suppressing axial misalignment during insertion of the connecting part 2 into the spark plug hole H and displacement due to vibration or the like. Furthermore, when mounting the coil main body part 11 onto the spark plug hole H after insertion of the connecting part 2 into the spark plug hole H, axial misalignment is suppressed, thus improving assembly capability. The shape of the connecting part 2 will be described in more detail later.
[0021] Next, the mounting structure of the ignition coil 1 to the spark plug hole H will be described in detail. Fig. Figure 2 shows the state of the ignition coil 1 before bending the connecting part 2 during the mounting of the ignition coil 1 at the spark plug hole H. On the other hand, it shows Fig. 1. Check the condition of ignition coil 1 after mounting it at spark plug hole H. As shown in the Fig. 1 and Fig. As shown in Figure 2, the spark plug hole H, in which the connecting part 2 of the ignition coil 1 is received, has a distal half-section H21, located on the distal side of the bend H1, and a proximal half-section H22, located on the proximal side of the bend H1. The distal half-section H21 is a circular hole with a substantially constant diameter and extends to a mounting section of the spark plug P. The proximal half-section H22, on the other hand, is a tapered hole whose diameter gradually increases from the bend H1 to the proximal side. The bend H1 is located at an intermediate position in the direction of extension of the spark plug hole H. It should be noted that the bend H1 can be located either distal or proximal to its position shown in the drawings.
[0022] The spark plug hole H is formed at a predetermined position in the cylinder head E1 for each cylinder of the machine. The axis L1 of the distal half-section H21 is inclined relative to the axis L2 of the proximal half-section H22. The axis L2 extends in a direction perpendicular to a first surface E11 of the cylinder head E1, where the proximal half-section H22 opens. The bend angle of the bend H1 is determined by the inclination angle θ of the axis L1 with respect to the axis L2 (see Fig. 1) shown, which in the present embodiment is equal to the taper angle of the proximal half-part H22. That is, in the left half of the section shown in the Fig. 1 and Fig. In the cross-section shown in Figure 2, the inner circumferential surface of the proximal half-part H22 continues from the inner circumferential surface of the distal half-part H21 without bending; in contrast, the bend H1 is formed in the right half of the cross-section.
[0023] Furthermore, a first inner diameter D1 of the spark plug hole H at the distal half-part H21 and a second inner diameter D2 of the spark plug hole H at the proximal inlet part H2, which opens on the proximal side of the proximal half-part H22, satisfy the relationship D2 > D1 (compare Fig. 2) Therefore, the connecting part 2 has the tubular main section 21, which straddles the bend H1 of the spark plug hole H, and the proximal tubular section 22, which is located on the proximal side of the tubular main section 21. The first ribs 31 and the second ribs 32 are provided in the tubular main section 21 and the proximal tubular section 22, respectively. The tubular main section 21 is opposite both a section of the distal half H21 of the spark plug hole H and a section of the proximal half H22 of the spark plug hole H, which are continuous with each other, with the bend H1 located between them. On the other hand, the proximal tubular section 22 is opposite a section of the proximal half-part H22 of the spark plug hole H, which includes the proximal inlet part H2.
[0024] As in Fig. As shown in Figure 1, the spark plug P is arranged to close a distal end hole H3 that extends from the distal half-section H21. The distal end hole H3 is a circular hole with a substantially constant diameter that is smaller than the diameter of the distal half-section H21. The distal end of the spark plug P is arranged to face a (not shown) combustion chamber of the machine. The spark plug P has an insulator P1 and a terminal P2 (see Figure 1). Fig. 2) The spark plug P comprises a housing P3, which holds the insulator P1, a center electrode P4, which projects from the insulator P1 towards the proximal side, and a ground electrode P5 opposite the center electrode P4. Furthermore, the spark plug P also has a threaded section formed in an outer circumferential surface of the housing P3 and a hexagonal section formed on the proximal side of the threaded section for engagement with a tool. The spark plug P is fitted and secured in the spark plug hole H.
[0025] As in the Fig. As shown in Figures 3 to 5, the connecting part 2 consists of a tubular, one-piece molded part formed entirely from an electrically insulating elastic material such as rubber. The connecting part 2 is designed to be freely elastically deformable according to the shape of the spark plug hole H and to be held in a bent state. The connecting part 2 has a straight, distal tubular section 23 formed on the distal side of the tubular main section 21 and attached to a head section of the insulator P1 of the spark plug P. The connecting part 2 further has a straight, tubular intermediate section 24 formed between the tubular main section 21 and the proximal tubular section 22.Each of the distal tubular section 23 and the intermediate tubular section 24 has a flat cylindrical outer circumferential surface without ribs and has a substantially constant outer diameter. Furthermore, both the distal tubular section 23 and the intermediate tubular section 24 have a smaller thickness and lower stiffness and can therefore be elastically deformed more easily than those sections of the connecting part 2 on which ribs are formed. Moreover, the outer diameter d3 of the distal tubular section 23 and the outer diameter d4 of the intermediate tubular section 24 satisfy the relationship d4 > d3 (see Figure 1). Fig. 5).
[0026] As in Fig. As shown in Figure 2, an electrically conductive element 4 is received in a cylindrical bore 20 that axially penetrates the connecting part 2. This element electrically connects the coil main body part 11 and the spark plug P. In the present embodiment, the electrically conductive element 4 is formed from a spring that is elastically deformable in the axial direction. The distal end of the electrically conductive element 4 is located within the distal tubular section 23. The insulator P1 is inserted into the distal tubular section 23 from its proximal end, thereby bringing the electrically conductive element 4 into contact with the head terminal P2.The axial length of the distal tubular section 23 can be suitably adjusted to obtain a desired fit, taking into account the extent of compression deformation when the head section of the insulator P1 is inserted into the distal tubular section 23.
[0027] As in Fig. As shown in Figure 4, the first ribs 31, each having the form of a projection extending outwards in the radial direction X, are formed at a plurality of locations on the outer circumferential surface of the tubular main section 21 of the connecting part 2. In particular, in the present embodiment, eight first ribs 31 are formed at eight locations each on the outer circumferential surface of the tubular main section 21 of the connecting part 2. The first ribs 31 each have a substantially trapezoidal cross-sectional shape, project radially, and together form a gear-like outer shape. The first ribs 31 extend parallel to each other along the axis L of the connecting part 2. Furthermore, the first ribs 31 extend over the entire length from the proximal side to the distal side of the tubular main section 21, i.e.,from the distal end position of the tubular intermediate section 24 to the proximal end position of the tubular distal section 23 (see . Fig. 3).
[0028] As in Fig. As shown in Figure 3, each of the first ribs 31 has a tapered section 311 at a distal end, which slopes downwards towards the distal side. Therefore, in a distal end section of the tubular main section 21, the diameter of the first rib, which is the diameter of the Fig. The imaginary circumscribing circle C1 shown in Figure 4 gradually tapers towards the distal side. In the tubular main section 21, with the exception of its distal end portion, the first rib diameter is essentially constant and has a maximum value of d1. Furthermore, distal ends of the tapered sections 311 of the first ribs 31 are connected to the distal tubular section 23. Therefore, the minimum value d11 of the first rib diameter is greater than or equal to the outer diameter d3 of the distal tubular section 23, which is shown in Figure 4. Fig. 5 is shown. This means that the following relationship is satisfied: d1 > d11 ≥ d3. In the distal end part of the tubular main section 21, where the tapered sections 311 of the first ribs 31 are formed, the first rib diameter increases towards the proximal side and approaches the maximum value d1.
[0029] As above, each of the first ribs 31 of the tubular main section 21 has the tapered section 311 formed at its distal end, so that the tubular main section 21 as a whole has a tapered shape that tapers towards the distal side, thereby improving insertion.
[0030] The tubular main section 21 is connected at its proximal side and with the first rib diameter, which is kept essentially constant at the maximum value d1, to the tubular intermediate section 24, which has an essentially constant diameter. Furthermore, the outer diameter d4 of the tubular intermediate section 24, which is in Fig. As shown in Figure 5, the diameter of the first rib is greater than or equal to the maximum value d1 and is therefore larger than the outer diameter d3 of the distal tubular section 23 (i.e., d4 ≥ d1 > d11 ≥ d3). To achieve the above relationship, in an end part of the tubular main section 21 on the side of the tubular intermediate section 24, those sections of the tubular main section 21 located between the circumferentially adjacent first ribs 31 (i.e., those sections of the tubular main section 21 in which no first ribs 31 are formed) are designed to gradually thicken towards the proximal side and project radially outwards. Consequently, in the end part of the tubular main section 21 on the side of the tubular intermediate section 24, the stiffness of the tubular main section 21 is improved and the protruding height of the first ribs 31 decreases towards the proximal side.
[0031] It is preferred that the first ribs 31 are arranged uniformly at substantially equal intervals in the circumferential direction on the outer circumferential surface of the tubular main section 21. The projecting ends of the first ribs 31 point through a gap formed between them to the inner circumferential surface of the spark plug hole H, which is located outside the first ribs 31 in the radial direction X. The larger the gap, the more the insertion is improved. However, there is a risk of axial misalignment. Therefore, it is preferable that, near and on the distal side of the bend H1, the inner circumferential surface of the spark plug hole H and the first ribs 31 are formed close together with a small gap between them, which lies within a range that does not impair insertion. A first inner diameter D1 (compare Fig. 2) in the distal half H21 of the spark plug hole H and the maximum value d1 (compare Fig. 4) of the first rib diameter the relationship D1 > d1.
[0032] The axial length of the tubular main section 21, on which the first ribs 31 are arranged, is not necessarily limited, but can be suitably adjusted depending on the position of the bend H1 in the spark plug hole H. In particular, taking into account the length of the distal tubular section 23, which is mounted on the spark plug P, the length of the proximal tubular section 22, and the like, the proximal end position of the first ribs 31 can be adjusted to a position within a range of 30% to 80% of the length of the connecting part 2 from the distal end position of the connecting part 2 (i.e., the distal end position of the distal tubular section 23).Furthermore, to improve the stiffness of the connecting part 2, it is preferable that the axial length of the first ribs 31 be set as long as possible within the above range, such that the proximal end position of the first ribs 31 lies on the proximal side of the bend H1 of the spark plug hole H. Additionally, a sealing part 25 is typically provided integrally with the connecting part 2 on its proximal side. In this case, the length of the connecting part 2 (hereinafter referred to as the joint length, if applicable) is the length including the sealing part 25 (i.e., the axial length from the distal end position of the distal tubular section 23 to the proximal end position of the sealing part 25). The sealing part 25 will be described in detail later.
[0033] The number of first ribs 31 is not necessarily limited, but to improve insertion ease as guides during insertion of the connecting part 2 into the spark plug hole H, it is preferable for the first ribs 31 to be formed at three or more locations on the outer circumferential surface of the tubular main section 21. For example, the number of first ribs 31 can be suitably adjusted within a range of 4 to 10 locations on the outer circumferential surface of the tubular main section 21, according to the outer diameter of the proximal or distal end of the tubular main section 21, the inner diameter of the spark plug hole H, and the like, to achieve the desired insertion ease and rigidity. Similarly, the width and protruding height of the first ribs 31 can also be suitably adjusted.
[0034] As in Fig. As shown in Figure 6, the connecting part 2 is attached to a high-voltage tower part 12 on the proximal side of the spark plug hole H. The high-voltage tower part 12 protrudes from the coil body part 11. The high-voltage tower part 12 contains a high-voltage terminal 13 and a resistor 131. The high-voltage tower part 12 is inserted into the proximal tubular section 22 of the connecting part 2 from its distal end, so that the high-voltage tower part 12 is inserted into the cylindrical hole 20 and a proximal end of the electrically conductive element 4 is brought into contact with the resistor 131. Consequently, the high-voltage terminal 13 and the electrically conductive element 4 are electrically connected to each other via the resistor 131.
[0035] The main coil body part 11 has an electrically insulating coil housing 14, which is arranged on the proximal side of the high-voltage tower part 12. The coil housing 14 contains: a primary coil 151 and a secondary coil 152, which are arranged coaxially to each other; a central core 161, which is arranged inside the coils; and an outer circumferential core 162, which is arranged on the outer circumference of the coils. Consequently, a high voltage generated in the secondary coil 152 can be output from the high-voltage terminal 13 and then applied to the spark plug P via the electrically conductive element 4.
[0036] As in Fig. As shown in Figure 4, the second ribs 32, each projecting outwards in the radial direction X, are formed at a plurality of locations on the outer circumferential surface of the proximal tubular section 22 of the connecting part 2. In particular, in the present embodiment, eight second ribs 32 are formed at eight locations each on the outer circumferential surface of the proximal tubular section 22 of the connecting part 2. The second ribs 32 each have a substantially trapezoidal cross-sectional shape, project radially, and together form a gear-like outer shape. The second ribs 32 extend parallel to each other along the axis L of the connecting part 2. Furthermore, the second ribs 32 extend over the entire length from the proximal side to the distal side of the proximal tubular section 22, i.e., to the proximal end position of the tubular intermediate section 24.
[0037] As in Fig. As shown in Figure 3, each of the second ribs 32 has a tapered section 321 at its distal end, which slopes downwards towards the distal side. Therefore, the second rib diameter, which is the diameter of the in Fig. The imaginary circumscribing circle C2 shown in Figure 4 tapers gradually towards the distal side in a distal end section of the proximal tubular section 22. In the proximal tubular section 22, with the exception of its distal end portion, the second ribs 32 exhibit a slight inclination; and the second rib diameter has a maximum value d2 at the proximal end of the proximal tubular section 22. It is preferable that the second ribs 32 have an inclination equal to the taper angle of the proximal half-section H22, so that the proximal tubular section 22 comes into surface contact with the inner circumferential surface of the spark plug hole H on the proximal side. The inclination of the second ribs 32 at their tapered sections 321 is greater than that at the proximal tubular section 22 on the proximal side of the tapered sections 321.Furthermore, the distal ends of the tapered sections 321 of the second ribs 32 are connected to the tubular intermediate section 24. Therefore, the minimum value d21 of the second rib diameter is greater than or equal to the outer diameter d4 of the tubular intermediate section 24, which is located in . Fig. 5 is shown. This means that the following relationship is satisfied: d2 > d21 ≥ d4. In the distal end part of the proximal tubular section 22, where the tapered sections 321 of the second ribs 32 are formed, the second rib diameter increases towards the proximal side and approaches the maximum value d2.
[0038] As above, each of the second ribs 32 of the proximal tubular section 22 has the tapered section 321 formed at its distal end, so that the proximal tubular section 22 as a whole has a tapered shape that tapers towards the distal side, thereby improving insertion.
[0039] It is preferred that the second ribs 32 are arranged uniformly at substantially equal intervals in the circumferential direction on the outer circumferential surface of the proximal tubular section 22. The projecting ends of the second ribs 32 point, through a gap formed between them, to the inner circumferential surface of the spark plug hole H, which is located outside the second ribs 32 in the radial direction X. The larger the gap, the more the insertion is improved. However, there is a risk of axial misalignment. Therefore, it is preferable that the inner circumferential surface of the proximal half-section H22 on the spark plug hole entry side and the second ribs 32 are formed close together with a small gap between them, which lies within a range that does not impair insertion.In this case, the second inner diameter D2 at the proximal-side inlet part H2 of the spark plug hole H and the maximum value d2 of the second rib diameter satisfy the relationship. D2>d2(>D1>d4≥d1>d11≥d3).
[0040] The axial length of the proximal tubular section 22, on which the second ribs 32 are arranged, is not necessarily limited; however, it is preferred to adjust the axial length of the proximal tubular section 22 according to the length of the connecting part 2, including the sealing part 25, such that the axial length of the first ribs 31, which straddle the bend H1 of the spark plug hole H, is greater than the axial length of the proximal tubular section 22. In particular, the distal end position of the second ribs 32, which are inserted into the proximal inlet part H2 of the spark plug hole H, can, for example, be positioned within a range of 1% to 20% of the length of the connecting part 2 from the proximal end position of the connecting part 2 (i.e.,The proximal end position of the sealing part 25) is adjusted according to the arrangement of the first ribs 31 and the like, in order to maintain the effect of axial alignment on the spark plug hole inlet side of the proximal half-section H22 of the spark plug hole H. It is preferred to adjust the distal end position of the second ribs 32, within a range where the axial length of the first ribs 31 can be secured, to a position 5% or more of the length of the connecting part 2 from the proximal end position of the connecting part 2. In this case, it will be possible to secure the length for which the proximal tubular section 22 makes surface contact with the inner circumferential surface of the spark plug hole H near the proximal inlet section H2, thereby improving the function of the second ribs 32 as guides.
[0041] The number of second ribs 32 is not necessarily limited, but with a view to improving the ease of insertion as guides during the insertion of the connecting part 2 into the spark plug hole H, it is preferable that the second ribs 32 are formed at three or more locations on the outer circumferential surface of the proximal-side tubular section 22. For example, the number of second ribs 32 can be suitably adjusted within a range of 4 to 10 locations on the outer circumferential surface of the proximal-side tubular section 22, according to the shape of the proximal-side half-section H2 of the spark plug hole H in which the proximal-side tubular section 22 is arranged, the inner diameter of the proximal-side inlet section H2 of the spark plug hole H, and the like, to achieve the desired ease of insertion and rigidity.Likewise, the width and the projecting height of the second ribs 32 can also be adjusted appropriately.
[0042] As in the Fig. 1 and Fig. As shown in Figure 2, the sealing element 25 is arranged on the proximal side of the spark plug hole H between the proximal inlet part H2 and the coil body part 11. The sealing element 25 is made of rubber and is integrally formed with the proximal end of the proximal tubular section 22 of the connecting element 2, which forms part of the connecting element 2. In this case, the sealing element 25 can be configured to project outwards in a flange shape from the proximal end of the proximal tubular section 22 in the radial direction X, thereby covering the proximal inlet part H2 of the spark plug hole H. The proximal inlet part H2 is configured to project annularly from the first surface E11 of the cylinder head E1, where the proximal end of the spark plug hole H opens. The proximal-side inlet part H2 acts as a locking part that locks the sealing part 25.A protruding end of the L-shaped bent sealing part 25 is locked to the proximal inlet part H2, so that the proximal opening of the spark plug hole H can be sealed by the sealing part 25.
[0043] The coil main body part 11 has a mounting flange part 141, which projects from one side of the coil housing 14. Furthermore, the mounting flange part 141 has a through-hole 142 through which a bolt is inserted. A support base part 13 is formed on the first surface E11 of the cylinder head E1, which faces the mounting flange part 141, and projects from this surface. The support base part 13 also has a threaded bore E13. In the above configuration, the coil main body part 11 can be fixed by placing the mounting flange part 141 onto the support base part E12 and attaching a bolt (not shown) to the proximal end of the spark plug hole H via the sealing part 25; consequently, the spark plug hole H can be hermetically sealed by the sealing part 25.
[0044] The ignition coil 1 can be mounted at the spark plug hole H, for example, as follows. First, as shown in Fig. Figure 2 shows the connecting part 2, whose proximal end is attached to the coil body part 11, being inserted from the proximal inlet part H2 of the spark plug hole H towards the distal side into the spark plug hole H in which the spark plug P is mounted. Specifically, the connecting part 2 is inserted coaxially with the axis L1 of the distal half-part H21 of the spark plug hole H, with the first ribs 31 formed on the tubular main section 21 acting as guides. Furthermore, the tapered sections 311 formed at their distal ends prevent the first ribs 31 from catching during insertion of the connecting part 2 into the spark plug hole H.In this case, the insertion force will not increase even if the difference between the maximum value d1 of the first rib diameter and the inner diameter D1 of the distal half-section H21 of the spark plug hole H is reduced; furthermore, the stiffness of the connecting part 2 is improved, thereby facilitating axial alignment between the connecting part 2 and the spark plug hole H. Consequently, the distal tubular section 23 of the connecting part 2 can coaxially insert the spark plug P therein.
[0045] Next, the tubular main section 21 of the connecting part 2 is further inserted towards the distal side of the spark plug hole H, while at the bend H1 of the spark plug hole H it is bent along the curved shape of the spark plug hole H. Consequently, the tubular main section 21 of the connecting part 2 can be bent and deformed such that: on the distal side of the connecting part 2, the distal tubular section 23 is held coaxially with the spark plug P; and on the proximal side of the bend H1, the axis L of the first ribs 31 is held coaxially with the axis L2 of the proximal half-section H22 of the spark plug hole H. Then, on the proximal side of the spark plug hole H, the proximal tubular section 22 of the connecting part 2 is fitted into the proximal inlet section H2 of the spark plug hole H, with the second ribs 32 acting as guides.In this case, the tapered sections 321, each formed at the distal ends of the second ribs 32, improve the insertion; and the difference between the maximum value d2 of the second rib diameter and the inner diameter D2 of the proximal half-part H22 can be reduced, thereby limiting the proximal tubular section 22 of the connecting part 2 to a coaxial position with the proximal half-part H22.
[0046] Fig. Figure 7 illustrates a first comparative example where the connecting part 2 has no second ribs 32 and has a constant diameter from a section of it facing the bend H1 of the spark plug hole H to its proximal end. In this configuration, it is difficult to perform the axial alignment between the connecting part 2 and the proximal half-section H22 of the spark plug hole H when the connecting part 2 is mounted at the proximal opening edge of the spark plug hole H while the connecting part 2 is bent along the curved shape of the spark plug hole H (e.g., in the curve indicated by the arrow in Figure 7). Fig. (in the direction specified in 7). Furthermore, with this configuration, as in Fig. As shown in Figure 8, the difference between the inner diameter D2 of the proximal inlet part H2 and the outer diameter of the connecting part 2 is large. Consequently, when a fastening bolt B is tightened and attached to the fastening flange part 141 of the coil body part 11, a rotational force acts (e.g., in the direction indicated by the arrow in Figure 8). Fig. (in the direction indicated in 8), making it easy for axial misalignment of the connecting part 2 to occur. As a result, it becomes necessary to provide a rotational stop or similar device to suppress displacement of the coil body part 11.
[0047] Fig. Figure 9 illustrates a second comparative example where a section of the connecting part 2 is thin-walled. In this configuration, the connecting part 2 can be easily deformed along the curved shape of the spark plug hole H; however, if the connecting part 2 is brought into contact with the bend H1 of the spark plug hole H, the contact section (e.g., the one in Fig. Section A) of the connecting part 2 with bend H1, as shown in Figure 9, may wear down. For example, if, in a state of the ignition coil 1 being mounted on an engine, the contact section of the connecting part 2 is displaced due to vibration or the like while in contact with bend H1, the thickness of the contact section may gradually decrease due to wear, leading to a decrease in the resistance voltage of the ignition coil 1.
[0048] In contrast, according to the present embodiment, the connecting part 2 has the first ribs 31 opposite the bend H1 of the spark plug hole H and the second ribs 32 opposite the proximal-side inlet part H2. This makes it possible to prevent axial misalignment over the entire length of the connecting part 2. Furthermore, the second ribs 32, which are arranged on the proximal-side inlet part H2, make it possible to constrain the connecting part 2 to be coaxial with the spark plug hole H, thus eliminating the need for a rotation stop when mounting the ignition coil 1 at the spark plug hole H.
[0049] Furthermore, the first ribs 31 and the second ribs 32 improve the stiffness of the connecting part 2, so that even if the first ribs 31 come into contact with the bend H1 of the ignition hole H, displacement of the connecting part 2 due to vibration or the like can be suppressed. Moreover, even if displacement of the connecting part 2 does occur, only the first ribs 31, which extend in the axial direction, come into contact with the bend H1 of the ignition hole H. Consequently, it becomes possible to prevent the thickness of the main body of the tubular main section 21 from being reduced due to wear; thus, it becomes possible to prevent the dielectric strength of the ignition coil 1 from being reduced. Other embodiments
[0050] In the first embodiment described above, the electrically conductive element 4 arranged within the connecting part 2 is formed by a spring and is electrically connected to the high-voltage terminal 13 via the resistor 131 of the high-voltage tower part 12. However, the electrically conductive element 4 can be formed from any electrically conductive element that can be bent and deformed together with the connecting part 2. Furthermore, in the first embodiment described above, the ignition coil 1 is applied to a vehicle engine. Alternatively, however, the ignition coil 1 can be attached to an internal combustion engine of a combined heat and power plant or the like.Furthermore, it should be noted that, unless otherwise specified, the reference numerals used in the first and subsequent embodiments are the same as those used in the previous embodiments and refer to the same components.
[0051] The present disclosure is not limited to the embodiments described above, but can also be implemented by various modifications of the embodiments described above without departing from the core of the present disclosure. For example, the configuration of the coil main body part 11 of the ignition coil 1 and the connection structure of the coil main body part 11 with the connecting part 2 can be suitably modified in various ways.
[0052] The following notes summarize the features of the present disclosure. [First clue]
[0053] Ignition coil (1) configured to supply a high voltage to a spark plug (P) arranged in a spark plug hole (H) with a bend (H1), the ignition coil comprising: a coil main body part (11) configured to be arranged on a proximal-side inlet part (H2) of the spark plug hole, the proximal-side inlet part having an inner diameter larger than that of the bend; and a connecting part (2) formed from a tubular elastic body which is bendable and deformable, wherein the connecting part has a proximal end which is attached to the coil main body part and a distal end which is to be attached to the spark plug, where: the connecting part has a plurality of first ribs (31) formed on an outer circumferential surface of a tubular main section (21) of the connecting part, each of the first ribs extending along an axis (L) of the connecting part, the tubular main section having a portion of it opposite the bend of the spark plug hole; The connecting part further comprises a plurality of second ribs (32) formed on an outer circumferential surface of a proximal tubular section (22) of the connecting part, each of the second ribs also extending along the axis of the connecting part, the proximal tubular section being located on a proximal side of the tubular main section; and when viewed along the axis of the connecting part, a maximum value d1 of a first rib diameter, represented by the diameter of an imaginary circumscribing circle (C1) with its center (c1) on the axis and circumscribing tips of the first ribs, and a maximum value d2 of a second rib diameter, represented by the diameter of an imaginary circumscribing circle (C2) with its center (c2) on the axis and circumscribing tips of the second ribs, satisfy the relationship d2 > d1. [Second clue]
[0054] Ignition coil according to the first indication, wherein the first ribs are arranged continuously on both a distal side and a proximal side of the part of the tubular main section that is to be opposite the bend of the spark plug hole. [Third clue]
[0055] Ignition coil according to the first or second indication, wherein each of the first ribs has a tapered section (311) at a distal end thereof, where the first rib diameter decreases towards the distal side. [Fourth clue]
[0056] Ignition coil according to one of the first to third indications, wherein the second ribs are arranged continuously from a proximal side to a distal side in order to be directed towards a proximal end part of the spark plug hole which includes the proximal inlet part. [Fifth clue]
[0057] Ignition coil according to one of the first to fourth notes, wherein each of the second ribs has a tapered section (321) at a distal end thereof, where the second rib diameter decreases towards the distal side. [Sixth clue]
[0058] Ignition coil according to one of the first to fifth instructions, wherein: the maximum value d1 of the first rib diameter and a first inner diameter D1, which is the inner diameter of the spark plug hole at the bend, satisfy the relationship D1 > d1; and the maximum value d2 of the second rib diameter and a second inner diameter D2, which is the inner diameter of the spark plug hole on the proximal-side inlet part, satisfy the relationship D2 > d2. [Seventh clue]
[0059] Ignition coil according to one of the first to sixth instructions, wherein: the connecting part further comprises a straight shaped distal tubular section (23) formed on the distal side of the tubular main section in order to be mounted on a head section of the spark plug; and An outer diameter d3 of the distal tubular section and the maximum value d1 and a minimum value d11 of the first rib diameter satisfy the relationship d1 > d11 ≥ d3. [Eighth clue]
[0060] Ignition coil according to the seventh note, wherein the connecting part further comprises a straight tubular intermediate section (24) formed between the tubular main section and the proximal tubular section; and An outer diameter d4 of the tubular intermediate section and the maximum value d2 and a minimum value d21 of the second rib diameter satisfy the relationship d2 > d21 ≥ d4. [Ninth clue]
[0061] Ignition coil according to the eighth note, wherein the outer diameter d3 of the distal tubular section and the outer diameter d4 of the tubular intermediate section satisfy the relationship d4 > d3.
[0062] Although the present disclosure has been described according to the foregoing embodiments, it is understood that the present disclosure is not limited to these embodiments and structures. Instead, the present disclosure includes various modifications and changes within equivalent areas. Additionally, it also includes various combinations and modes within the category and scope of the technical idea of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION
[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature
[0000] JP 2023-081022 A
[0001] JP 4267042 B2
[0005]
Claims
[1] Ignition coil (1) configured to supply a high voltage to a spark plug (P) arranged in a spark plug hole (H) with a bend (H1), the ignition coil comprising: a coil main body part (11) configured to be arranged on a proximal-side inlet part (H2) of the spark plug hole, the proximal-side inlet part having an inner diameter larger than that of the bend; and a connecting part (2) formed from a tubular elastic body which is bendable and deformable, wherein the connecting part has a proximal end which is attached to the coil main body part and a distal end which is to be attached to the spark plug, where: the connecting part has a plurality of first ribs (31) formed on an outer circumferential surface of a tubular main section (21) of the connecting part, each of the first ribs extending along an axis (L) of the connecting part, the tubular main section having a portion of it opposite the bend of the spark plug hole; the connecting part further comprises a plurality of second ribs (32) formed on an outer circumferential surface of a proximal tubular section (22) of the connecting part, each of the second ribs also extending along the axis of the connecting part, the proximal tubular section being located on a proximal side of the tubular main section; and When viewed along the axis of the connecting part, a maximum value d1 of a first rib diameter, represented by the diameter of an imaginary circumscribing circle (C1) with its center (c1) on the axis and circumscribing tips of the first ribs, and a maximum value d2 of a second rib diameter, represented by the diameter of an imaginary circumscribing circle (C2) with its center (c2) on the axis and circumscribing tips of the second ribs, satisfy the relationship d2 > d1. [2] Ignition coil according to claim 1, wherein the first ribs are arranged continuously on both a distal side and a proximal side of the part of the tubular main section which is to be opposite the bend of the spark plug hole. [3] Ignition coil according to claim 2, wherein each of the first ribs has a tapered section (311) at a distal end thereof, where the first rib diameter decreases towards the distal side. [4] Ignition coil according to claim 1, wherein the second ribs are arranged continuously from a proximal side to a distal side in order to be directed towards a proximal end part of the spark plug hole which includes the proximal inlet part. [5] Ignition coil according to claim 4, wherein each of the second ribs has a tapered section (321) at a distal end thereof, where the second rib diameter decreases towards the distal side. [6] Ignition coil according to claim 1, wherein: the maximum value d1 of the first rib diameter and a first inner diameter D1, which is the inner diameter of the spark plug hole at the bend, satisfy the relationship D1 > d1; and the maximum value d2 of the second rib diameter and a second inner diameter D2, which is the inner diameter of the spark plug hole on the proximal side of the inlet part, satisfy the relationship D2 > d2. [7] Ignition coil according to claim 6, wherein the connecting part further comprises a straight-shaped distal tubular section (23) formed on the distal side of the tubular main section in order to be mounted on a head section of the spark plug; and An outer diameter d3 of the distal tubular section and the maximum value d1 and a minimum value d11 of the first rib diameter satisfy the relationship d1 > d11 ≥ d3. [8] Ignition coil according to claim 7, wherein: the connecting part further comprises a straight tubular intermediate section (24) formed between the tubular main section and the proximal tubular section; and An outer diameter d4 of the tubular intermediate section and the maximum value d2 and a minimum value d21 of the second rib diameter satisfy the relationship d2 > d21 ≥ d4. [9] Ignition coil according to claim 8, wherein the outer diameter d3 of the distal tubular section and the outer diameter d4 of the tubular intermediate section satisfy the relationship d4 > d3.
Citation Information
Patent Citations
Electronic apparatus, computer program and job execution method
JP2023081022A
Ignition coil device for internal combustion engine
JP4267042B2