JP7476618B2 - Ignition coil - Google Patents

Description

The present invention relates to an ignition coil.

Patent Document 1 discloses an ignition coil for an internal combustion engine that includes a primary coil, a secondary coil, and a core that are magnetically coupled to each other, a resistor that suppresses noise when a discharge occurs in the spark plug, and a case. The case has a case body that houses the primary coil and secondary coil, and a cylindrical tower portion that protrudes from the case body.

In the ignition coil described in Patent Document 1, the case body is filled with a filling resin. Patent Document 1 also discloses an example in which filling resin is arranged around the resistor. By sealing the resistor with filling resin, deterioration of the resistor can be suppressed.

Furthermore, in Patent Document 1, the inner periphery of the tower section includes a tower reduced diameter section that protrudes toward the inner periphery, and the tip of the resistor includes a resistor protrusion that protrudes toward the tip. The resistor protrusion is press-fitted into the tower reduced diameter section, thereby sealing the gap between the tower reduced diameter section and the resistor protrusion.

JP 2018-155212 A

However, in the ignition coil described in Patent Document 1, stress occurs near the press-fit portion between the resistor and the tower section, and there is a risk of cracks occurring in the tower section due to thermal stress, raising concerns about reduced durability of the resistor and tower section.

The present invention was made in consideration of these problems, and aims to provide an ignition coil for an internal combustion engine that can improve the durability of the resistor and tower section.

One aspect of the present invention is a case (2) having a case body (21) and a cylindrical tower portion (22) protruding from the case body;
A resistor (3) disposed within the tower portion;
A filled resin (4) is filled in the case body,
The tower portion has a resistor arrangement portion (220) including a tip opposing wall (221) that faces the resistor from the tip side in the protruding direction (X) of the tower portion, a base end opposing wall (222 ) that faces the resistor from the base end side in the protruding direction, and a peripheral wall (223) that connects the tip opposing wall and the base end opposing wall ,
A tip opening (225) is formed in the tip facing wall to expose the resistor toward the tip side in the protruding direction,
When the resistor is sandwiched between the tip opposing wall and the base opposing wall, the tip opposing wall abuts against the resistor over the entire circumference of the tip opening,
the tower portion has a communication hole (220a) on a base end side of the peripheral wall located in the space within the case body, the communication hole (220a) communicating between an area within the resistor arrangement portion in the tower portion and an area within the case body,
The ignition coil (1) has a structure in which a part of the filling resin is filled around the resistor in the tower portion through the communication hole.

In the ignition coil of the above embodiment, the tower portion has a tip end facing wall that faces the resistor from the tip side in the protruding direction of the tower portion, and a base end facing wall that faces the resistor from the base side in the protruding direction. In this way, when the resistor is sandwiched between the tip end facing wall and the base end facing wall in the protruding direction, the tip end facing wall abuts the resistor over the entire circumference of the tip opening. Therefore, leakage of the filling resin at the abutment portion between the tip end of the resistor and the tip end facing wall can be prevented, and it is easy to suppress concentration of stress on the resistor and the tower portion. Furthermore, the tower portion has a communication hole that communicates the area in the tower portion where the resistor is arranged with the area in the case body. And, a part of the filling resin is filled around the resistor in the tower portion through the communication hole. Therefore, even if the resistor is sandwiched between the tip end facing wall and the base end facing wall in the protruding direction, the filling resin can be filled around the resistor through the communication hole. Therefore, surface deterioration of the resistor can be suppressed.

As described above, according to the above aspect, it is possible to provide an ignition coil for an internal combustion engine that can improve the durability of the resistor and the tower portion.
In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate a correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention.

FIG. 2 is a cross-sectional view of an ignition coil according to the first embodiment. FIG. 4 is an enlarged cross-sectional view of a resistor and its surroundings in the ignition coil according to the first embodiment. FIG. 4 is an enlarged cross-sectional view of the periphery of a resistor in the ignition coil according to the first embodiment, the cross-sectional view passing through a communication hole. 4 is a view taken along line IV in FIG. 2, showing a base end portion of a resistor arrangement portion and a resistor body. 3 is a view taken along line V in FIG. 2 , showing the tip of the resistor arrangement portion and a resistor body; FIG. 4 is a perspective view of a base end portion of a resistor arrangement portion in the first embodiment. FIG. 11 is a cross-sectional view illustrating the state in which the resistor is inserted into the tower portion, illustrating the state in which the resistor is assembled into the case in the first embodiment. FIG. 11 is a cross-sectional view illustrating a state in which a resistor arrangement portion is sandwiched between a receiving jig and an ultrasonic horn, illustrating a state in which a resistor is assembled to a case in the first embodiment. FIG. 10 is a cross-sectional view illustrating how the resistor is assembled to the case in the first embodiment, showing how the tip opposing wall is welded to the resistor. FIG. 11 is a perspective view of a base end portion of a resistor arrangement portion in a second embodiment. FIG. 11 is an enlarged cross-sectional view of a resistor and its surroundings in an ignition coil according to a third embodiment. FIG. 11 is an enlarged cross-sectional view of the periphery of a resistor in an ignition coil according to a third embodiment, the cross-sectional view passing through a communication hole. FIG. 13 is a cross-sectional view illustrating the state in which the resistor is inserted into the tower portion, illustrating the state in which the resistor is assembled into the case in the third embodiment. FIG. 13 is a perspective view of a resistor arrangement portion before welding in the third embodiment; FIG. 13 is a cross-sectional view illustrating a state in which a resistor is assembled to a case in the third embodiment, the cross-sectional view showing a state in which a resistor arrangement portion is sandwiched between a receiving jig and an ultrasonic horn. FIG. 13 is a cross-sectional view illustrating how the resistor is assembled to the case in the third embodiment, the cross-sectional view showing how the tip opposing wall and the base opposing wall are each welded to the resistor. FIG. 13 is a perspective view of a base end portion of a resistor arrangement portion before welding in the fourth embodiment. 13 is a cross-sectional view of a base end portion of a resistor arrangement portion before welding in embodiment 5. FIG.

(Embodiment 1)
An embodiment of an ignition coil will be described with reference to FIGS.
As shown in FIG. 1, the ignition coil 1 of this embodiment includes a case 2, a resistor 3, and a filling resin 4.

The case 2 has a case body 21 and a cylindrical tower portion 22 that protrudes from the case body 21. Hereinafter, the direction in which the tower portion 22 protrudes from the case body 21 is referred to as the X direction. One side in the X direction, the side where the tower portion 22 protrudes from the case body 21 (e.g., the lower side in Fig. 1), is referred to as the tip side, and the opposite side is referred to as the base side. The resistor 3 is disposed in the tower portion 22. The filling resin 4 is filled in the case body 21.

As shown in Figs. 1 to 3, the tower section 22 includes a tip end facing wall 221 and a base end facing wall 222. The tip end facing wall 221 faces the resistor 3 from the tip side. The base end facing wall 222 faces the resistor 3 from the base end side. The tip end facing wall 221 is formed with a tip opening 225 that exposes the resistor 3 toward the tip side. The tip end facing wall 221 abuts against the resistor 3 over the entire circumference of the tip opening 225. As shown in Figs. 3 and 6, the tower section 22 has a communication hole 220a that communicates between the region in the tower section 22 where the resistor 3 is disposed and the region in the case main body 21. A part of the filling resin 4 is filled around the resistor 3 in the tower section 22 through the communication hole 220a.
The ignition coil 1 of this embodiment will now be described in detail.

The ignition coil 1 is connected to a spark plug installed in an internal combustion engine of an automobile, cogeneration system, etc., and is used as a means for applying high voltage to the spark plug.

As shown in FIG. 1, the case 2 is made of electrically insulating thermoplastic resin or the like, and is formed by integrally molding the case body 21 and the tower section 22. The case body 21 is open on the base end side in the X direction. The case body 21 has a case side wall 211 that covers the inner space from the outer periphery side, and a case bottom wall 212 that is formed to cover the case side wall 211 from the tip side. The tower section 22 extends from approximately the center position of the case bottom wall 212 toward the tip side.

3 and 4, the tower section 22 is formed in a cylindrical shape having a certain thickness. When the case 2 is viewed alone (i.e., when the filling resin 4 or the like is not filled in the case 2), the space in the tower section 22 is connected to the space in the case body 21. The base end of the tower section 22 is provided with a resistor arrangement section 220 in which the resistor 3 is arranged. The resistor arrangement section 220 has a tip facing wall 221, a base end facing wall 222, and a peripheral wall 223. As described above, the tip facing wall 221 faces the resistor 3 from the tip side, and the base end facing wall 222 faces the resistor 3 from the base end side. The peripheral wall 223 connects the tip facing wall 221 and the base end facing wall 222 in the X direction and is formed to cover the resistor 3 from the outer periphery.

4 and 6, the base end facing wall 222 is formed in an annular shape. That is, the base end facing wall 222 has a base end opening 224 penetrating in the X direction at its center. As shown in FIG. 4, when viewed from the base end side, the base end opening 224 is formed to have a smaller diameter than the base end surface 331 of the resistor 3 so as to fit inside the base end surface 331 of the resistor 3. As shown in FIG. 2 and FIG. 3, the base end facing wall 222 abuts against the outer peripheral end of the base end surface 331 of the resistor 3. A connection member 5 for establishing electrical continuity between the resistor 3 and the secondary coil 12 described below is inserted into the base end opening 224, and the connection member 5 is in contact with the resistor 3. The outer peripheral edge of the base end facing wall 222 is connected to the base end of the peripheral wall 223.

As shown in Figures 3, 4, and 6, the base end of the peripheral wall 223 has a communication hole 220a formed so as to be recessed from the base end edge of the peripheral wall 223 toward the tip end. The communication hole 220a penetrates the peripheral wall 223 in the radial direction and is open on the base end side. A plurality of communication holes 220a (specifically, four) are formed and are provided at equal intervals in the circumferential direction. The portion between the communication holes 220a adjacent in the circumferential direction at the base end of the peripheral wall 223 is a protruding piece 223a formed to protrude toward the base end side. A base end opposing wall 222 is formed so as to be connected to the inner circumferential surface of the protruding piece 223a.

2 and 3, the tip position of the communication hole 220a is located on the base end side of the resistor 3, which will be described later, but is not limited to this. The communication hole 220a is not blocked by the resistor 3. In this embodiment, the peripheral wall 223 is formed to provide a radial gap with the resistor 3. That is, the diameter of the inner peripheral surface of the peripheral wall 223 is larger than the diameter of the resistor 3. As a result, a gap is also formed between the communication hole 220a and the resistor 3. The aforementioned tip facing wall 221 is formed on the tip side of the resistor 3. It is also possible to make the diameter of the inner peripheral surface of the peripheral wall 223 equal to the diameter of the resistor 3. In this case, if the communication hole 220a is formed to be longer in the X direction than the base end cap 33, which will be described later, and to open toward the resistor body 31, which will be described later, of the resistor 3, it is possible to arrange the filling resin 4 around the resistor body 31.

As shown in Figures 2, 3, and 5, the tip facing wall 221 is formed to enclose the entire outer circumference of the tip surface 321 of the resistor 3. The tip facing wall 221 is formed to abut against the entire circumference of the tip surface 321 of the resistor 3 by welding, which will be described later. The tip facing wall 221 has a tip opening 225 that penetrates in the X direction at its center. As shown in Figure 5, when viewed from the tip side, the tip opening 225 is formed to have a smaller diameter than the tip surface 321 of the resistor 3 so that it fits inside the tip surface 321 of the resistor 3.

As shown in Figures 2 and 3, a large-diameter cylindrical surface portion 226 is formed on the tip side of the resistor arrangement portion 220 in the tower portion 22, and has an inner diameter larger than the inner diameter of the resistor arrangement portion 220 and is open on the tip side. Although not shown, a part of a coil spring arranged in a joint member attached to the tower portion 22 is inserted into the large-diameter cylindrical surface portion 226. The coil spring is used to provide electrical continuity between the resistor 3 and the spark plug.

A fitting protrusion 227 is formed on the outer periphery of the tower section 22 for fitting and holding a joint member (not shown). The fitting protrusion 227 is formed around the entire circumference of the tower section 22 and is formed to protrude toward the outer periphery. The joint member is formed with a recess that can fit into the protrusion of the tower section 22, and when the joint member is assembled to the tower section 22, the protrusion of the tower section 22 fits into the recess of the joint member, preventing the joint from coming off the tower section 22.

2 and 3, the resistor 3 is arranged in the resistor arrangement section 220. In this embodiment, the resistor 3 includes a resistor body 31, a tip cap 32 that covers the tip of the resistor body 31, and a base cap 33 that covers the base of the resistor body 31. The resistor body 31 is made of, for example, a ceramic resistor or a wire-wound resistor. The tip cap 32 and the base cap 33 are formed, for example, by pressing a metal plate into a cup shape. The tip of the resistor body 31 is inserted into the tip cap 32, and the base of the resistor body 31 is inserted into the base cap 33. The resistor 3 is formed so that the part where the tip cap 32 and the base cap 33 are arranged has a larger diameter than the other parts. The resistor 3 is formed symmetrically in the X direction.

2 and 3, the tip surface 321 of the tip cap 32 of the resistor 3 abuts against the tip facing wall 221 of the resistor arrangement section 220 around the entire circumference. The base end surface 331 of the base end cap 33 abuts against the base end facing wall 222 of the resistor arrangement section 220. A small gap is formed between almost the entire resistor 3 and the peripheral wall 223 of the resistor arrangement section 220.

As shown in FIG. 1, the case body 21 contains the primary coil 11, secondary coil 12, and core 13, which are magnetically coupled to each other. The primary coil 11 and secondary coil 12 are arranged concentrically on the inner and outer periphery. The secondary coil 12 is formed by winding a secondary electric wire, which is thinner than the primary electric wire constituting the primary coil 11, with more turns than the primary electric wire on the outer periphery side of the primary coil 11. The primary coil 11 is electrically connected to a terminal (not shown) of a connector part 213 formed to protrude from the case body 21. Power is supplied to the primary coil 11 from an external device through the connector part 213. The high voltage output side of the secondary coil 12 is electrically connected to the resistor 3 through a conductive connection member 5. The core 13 is inserted on the inner periphery side of the primary coil 11. The core 13 passes the magnetic flux generated by the current passing through the primary coil 11. For example, the core 13 can be made of an iron core, ferrite, amorphous, etc.

The filled resin 4 is filled in the case 2. The filled resin 4 is made of, for example, an electrically insulating thermosetting resin, and seals the components of the ignition coil 1 housed in the case 2. When filling the filled resin 4 in the case 2, the liquid resin before hardening that constitutes the filled resin 4 is poured from the opening on the base end side of the case body 21. As a result, the liquid resin fills the gaps in the case body 21. Here, as shown in FIG. 3, the liquid resin passes through the communication hole 220a and is also filled around the resistor 3 in the resistor arrangement section 220. As described above, the tip surface 321 of the tip cap 32 of the resistor 3 and the periphery of the tip opening 225 of the tip facing wall 221 are in contact with each other all around, which prevents the liquid resin from leaking out beyond the contact portion toward the tip side. That is, in this embodiment, liquid resin is filled into the inner area of the case 2 on the base end side from the contact portion between the tip surface 321 of the tip cap 32 of the resistor 3 and the tip facing wall 221. After the liquid resin has spread throughout the case 2, the temperature of the liquid resin is lowered, causing the liquid resin to harden and become the filled resin 4.

Next, an example of a method for arranging resistor elements 3 in resistor arrangement section 220 in this embodiment will be described with reference to FIGS.
In this embodiment, the shape of the resistor arrangement section 220 of the case 2 differs between a state after molding and before the resistor 3 is inserted and a state in which the resistor 3 is held. As shown in Fig. 7, in a state after molding the case 2 and before the resistor 3 is inserted into the case 2, the tip of the resistor arrangement section 220 (i.e., the portion that will eventually become the tip opposing wall 221) is a cylindrical initial tip section 61 that is aligned in the X direction. Then, the resistor 3 is inserted into the resistor arrangement section 220 from the tip side of the initial tip section 61.

Next, as shown in FIG. 8, a receiving jig 14 is placed on the base end side of the resistor arrangement section 220, an ultrasonic horn 15 is placed on the tip end side of the resistor arrangement section 220, and the resistor arrangement section 220 is sandwiched between the receiving jig 14 and the ultrasonic horn 15. The ultrasonic horn 15 is capable of generating ultrasonic vibrations. The horn end surface 151 facing the base end side of the ultrasonic horn 15 is curved to follow the initial tip portion 61 after deformation (i.e., the tip facing wall 221 after welding).

Then, while sandwiching the resistor arrangement portion 220 between the receiving jig 14 and the ultrasonic horn 15, ultrasonic vibration is generated in the ultrasonic horn 15. As a result, as shown in FIG. 9, the initial tip portion 61 melts and deforms along the horn end surface 151, and the ultrasonic horn 15 moves toward the base end by the amount of melting of the initial tip portion 61. Finally, the initial tip portion 61 is welded to cover the tip cap 32 of the resistor 3 all around, thereby forming the tip facing wall 221. In FIG. 9, the initial tip portion 61 before melting is shown by a dashed line. As described above, a state in which the resistor 3 is surrounded by the tip facing wall 221 and the base end facing wall 222 can be formed.

Next, the effects of this embodiment will be described.
In the ignition coil 1 of this embodiment, the tower section 22 has a tip end facing wall 221 facing the resistor 3 from the tip side, and a base end facing wall 222 facing the resistor 3 from the base end side. In this manner, when the resistor 3 is sandwiched between the tip end facing wall 221 and the base end facing wall 222 in the X direction, the tip end facing wall 221 abuts against the resistor 3 over the entire circumference of the tip opening 225. Therefore, leakage of the filled resin 4 at the abutment portion between the tip end of the resistor 3 and the tip end facing wall 221 can be prevented, and compared to the case where the resistor 3 is press-fitted into the tower section 22, radial stress is not generated in the resistor 3 and the tower section 22, and cracks can be prevented from occurring in the tower section 22. In addition, when the resistor 3 is press-fitted into the tower section 22, the relationship between the radial dimension of the resistor 3 and the radial dimension of the tower section 22 must be strictly defined, but since the press-fitting process is not necessary in this embodiment, it is easy to lower the requirement for dimensional accuracy between the resistor 3 and the tower section 22.

The tower section 22 also has a communication hole 220a that connects the area in the tower section 22 where the resistor 3 is arranged to the area in the case body 21. A part of the filling resin 4 is filled around the resistor 3 in the tower section 22 through the communication hole 220a. Therefore, even if the resistor 3 is sandwiched in the X direction between the tip end facing wall 221 and the base end facing wall 222, the filling resin 4 can be filled around the resistor 3 through the communication hole 220a. Therefore, surface deterioration of the resistor 3 can be suppressed.

The tip facing wall 221 is welded to the resistor 3. Therefore, as in the ignition coil 1 of this embodiment, after inserting the resistor 3 into the resistor arrangement section 220 with the tip side open, the tip facing wall 221 is welded to the resistor 3 to close the tip of the resistor arrangement section 220, thereby realizing a state in which the resistor 3 is sandwiched between the tip facing wall 221 and the base end facing wall 222. In addition, the vibration resistance of the resistor 3 can be improved. Accordingly, it is possible to suppress the contact between the resistor 3 and the member connected thereto, such as the coil spring, becoming unstable due to the generation of vibration in the ignition coil 1.

The base end facing wall 222 also has a base end opening 224 into which a connection member 5 that electrically connects the secondary coil 12 and the resistor 3 is inserted. Therefore, even if the base end facing wall 222 is disposed so as to face the resistor 3 from the base end side, it is easy to easily establish an electrical connection structure between the base end of the resistor 3 and the secondary coil 12.

The resistor 3 also has a shape that is symmetrical in the X direction. Therefore, when inserting the resistor 3 into the resistor arrangement section 220, there is no need to identify the position of the resistor 3 in the X direction, which makes it easier to improve the productivity of the ignition coil 1.

As described above, this embodiment provides an ignition coil for an internal combustion engine that can improve the durability of the resistor and tower section.

(Embodiment 2)
As shown in FIG. 10, this embodiment is an embodiment in which the shape of a base end opposing wall 222 is changed from that of the first embodiment.

In this embodiment, four base end opposing walls 222 are formed. The four base end opposing walls 222 are formed radially from the tips of the four protruding pieces 223a toward the inner periphery. The inner periphery end faces of the four base end opposing walls 222 are formed to face the center of the peripheral wall 223. The inner periphery region of the four base end opposing walls 222 constitutes the base end opening 224. The inner periphery end faces of the four base end opposing walls 222 are curved in an arc shape along an imaginary circle formed between them, but are not limited to this, and may be formed in other shapes, such as a flat shape. The gaps between the protruding pieces 223a adjacent to each other in the circumferential direction and between the base end opposing walls 222 form the communication holes 220a. In this embodiment, the communication holes 220a communicate with the base end opening 224.

The rest is the same as in the first embodiment.
In addition, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified.

This embodiment also provides the same effects as embodiment 1.

(Embodiment 3)
As shown in FIGS. 11 to 16, this embodiment is an embodiment in which the configurations of a distal end facing wall 221 and a proximal end facing wall 222 are changed from those of the first embodiment.

11 and 12, the tip facing wall 221 has a first portion 221a that protrudes from the peripheral wall 223 toward the inner periphery, and a second portion 221b that protrudes from the inner periphery of the first portion 221a toward the base end. The tip surface 321 of the tip cap 32 of the resistor 3 abuts against the base end side surface of the second portion 221b over the entire circumference. As described below, the second portion 221b is welded to the resistor 3 over the entire circumference.

The base end opposing wall 222 is formed from the tip of the peripheral wall 223 toward the inner periphery. In this embodiment, there are four base end opposing walls 222 formed at equal intervals in the circumferential direction. Note that FIG. 14 shows the initial base end 63, which is the state before the base end opposing walls are deformed. As shown in FIG. 11, each base end opposing wall 222 abuts against the outer periphery of the base end surface 331 of the base end cap 33 of the resistor 3 by welding, which will be described later. The inner periphery of the four base end opposing walls 222 constitutes the base end opening 224. The gap between the base end opposing walls 222 adjacent in the circumferential direction is the communication hole 220a. In this embodiment, the communication hole 220a and the base end opening 224 are in communication.

Next, an example of a method for arranging resistors 3 in resistor arrangement section 220 in this embodiment will be described with reference to Figures 12 to 16.

In this embodiment, the shape of the resistor arrangement section 220 of the case 2 differs between the state after molding and before the resistor 3 is inserted and the state in which the resistor 3 is held. As shown in FIG. 13, in the state after molding the case 2 and before the resistor 3 is inserted into the case 2, the tip end of the resistor arrangement section 220 (i.e., the portion that will eventually become the tip-facing wall 221) includes the above-mentioned first portion 221a and a cylindrical initial tube portion 62 that protrudes from the inner peripheral end of the first portion 221a toward the base end and has a smaller thickness than the first portion 221a.

After molding the case 2 and before inserting the resistor 3 into the case 2, the base end of the resistor arrangement section 220 (i.e., the portion that will eventually become the base end opposing wall 222) has a cylindrical initial base end 63 along the X direction. The initial base ends 63 are formed at four locations in the circumferential direction at predetermined intervals. The spaces between the initial base ends 63 in the circumferential direction form slits 64 that will eventually form communication holes. As shown in Figures 13 and 15, the resistor 3 is inserted into the resistor arrangement section 220 from the base end side of the initial base end 63 and is arranged on the end face on the base end side of the initial cylindrical section 62.

Next, as shown in FIG. 15, a receiving jig 14 is placed on the tip side of the resistor arrangement portion 220, an ultrasonic horn 15 is placed on the base end side of the resistor arrangement portion 220, and the resistor arrangement portion 220 is sandwiched between the receiving jig 14 and the ultrasonic horn 15. Here, the horn end surface 151 facing the tip side of the ultrasonic horn 15 is curved so as to follow the initial base end portion 63 after deformation (i.e., the base end facing wall 222 after welding). In addition, the center portion of the horn end surface 151 has a horn protrusion 152 that protrudes toward the center portion of the base end cap 33 of the resistor 3. The horn protrusion 152 is formed to a size that allows the connection member 5 to be inserted into the aforementioned base end opening 224 surrounded by the four base end facing walls 222 after deformation of the initial base end portion 63.

Then, while the resistor arrangement portion 220 is sandwiched between the receiving jig 14 and the ultrasonic horn 15, ultrasonic vibration is generated in the ultrasonic horn 15. As a result, as shown in FIG. 16, the initial base end portion 63 melts and deforms along the horn end surface 151 of the ultrasonic horn 15, and ultrasonic vibration is transmitted to the resistor 3 by the horn protruding portion 152. Then, as the ultrasonic vibration is transmitted to the resistor 3, the initial tubular portion 62 that is in contact with the tip end portion of the resistor 3 melts and deforms. Finally, the initial tubular portion 62 is welded to cover the tip cap 32 of the resistor 3 over the entire circumference, becoming a second portion 221b (described later) of the tip facing wall 221, and the initial base end portion 63 is partially welded to the base end cap 33 of the resistor 3 in the circumferential direction. Then, the region where the initial base end portion 63 after deformation in the circumferential direction does not reach the base end cap 33 of the resistor 3 becomes a communication hole 220a as shown in FIG. 12. As described above, a state can be formed in which the resistor 3 is surrounded by the tip end opposing wall 221 and the base end opposing wall 222 .
The rest is the same as in the first embodiment.

In this embodiment, the tip opposing wall 221 is welded to the tip portion of the resistor 3, and the base opposing wall 222 is welded to the base end portion of the resistor 3, so that the resistor 3 is reliably fixed by the tip opposing wall 221 and the base opposing wall 222. This improves the vibration resistance of the resistor 3. Accordingly, it is possible to suppress the contact between the resistor 3 and the member such as the coil spring connected thereto from becoming unstable due to the generation of vibration in the ignition coil 1.
In addition, the second embodiment has the same effects as the first embodiment.

(Embodiment 4)
17 , this embodiment is an embodiment in which the shape of the base end of the resistor arrangement portion 220 after the case 2 is molded and before the resistor 3 is inserted into the case 2 is changed from that of the third embodiment. Specifically, the outer circumferential surface of the initial base end 63 is a tapered surface 631. The tapered surface 631 is formed so that the thickness becomes smaller toward the base end of the initial base end 63.
The rest is the same as in the third embodiment.

In this embodiment, the initial base end portion 63 is easily melted during welding, and the productivity of the ignition coil 1 is easily improved.
In addition, the second embodiment has the same effects as the third embodiment.

(Embodiment 5)
18, this embodiment is an embodiment in which the shape of the base end of the resistor arrangement portion 220 after the case 2 is molded and before the resistor 3 is inserted into the case 2 is changed from that of the third embodiment. Specifically, the inner circumferential surface of the initial base end 63 is a tapered surface 632. The tapered surface 632 is formed so that the thickness becomes smaller toward the base end of the initial base end 63.
The rest is the same as in the third embodiment.

In this embodiment, the resistor 3 can be easily inserted into the resistor arrangement section 220 .
Furthermore, the initial base end portion 63 is easily melted during welding, which makes it easy to improve the productivity of the ignition coil 1.
In addition, the present embodiment has the same effects as the third embodiment.

The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the spirit of the present invention.

Reference Signs List 1 Ignition coil 2 Case 21 Case body 22 Tower portion 220a Communication hole 221 Tip end facing wall 222 Base end facing wall 3 Resistor 4 Filling resin

Claims (3)

A case (2) having a case body (21) and a cylindrical tower portion (22) protruding from the case body;
A resistor (3) disposed within the tower portion;
A filled resin (4) is filled in the case body,
The tower portion has a resistor arrangement portion (220) including a tip opposing wall (221) that faces the resistor from the tip side in the protruding direction (X) of the tower portion, a base end opposing wall (222 ) that faces the resistor from the base end side in the protruding direction, and a peripheral wall (223) that connects the tip opposing wall and the base end opposing wall ,
A tip opening (225) is formed in the tip facing wall to expose the resistor toward the tip side in the protruding direction,
When the resistor is sandwiched between the tip opposing wall and the base opposing wall, the tip opposing wall abuts against the resistor over the entire circumference of the tip opening,
the tower portion has a communication hole (220a) on a base end side of the peripheral wall located in the space within the case body, the communication hole (220a) communicating between an area within the resistor arrangement portion in the tower portion and an area within the case body,
A part of the filling resin is filled around the resistor in the tower portion through the communication hole. The communication hole is provided in a plurality of holes in a circumferential direction of the peripheral wall, the communication hole radially penetrating the peripheral wall and having an open base end side,
2. The ignition coil according to claim 1, wherein the tip opposing wall is welded to the resistor. An ignition coil according to claim 1 or 2, in which a primary coil (11) and a secondary coil (12) that are magnetically coupled to each other are arranged in the case body, and the base end facing wall has a base end opening (224) into which a connecting member (5) that electrically connects the secondary coil and the resistor is inserted.

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