JP6491886B2 - Ignition coil for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition coil for an internal combustion engine, and is particularly suitable when a structure surface is formed by two types of resin structures.

  In recent years, for internal combustion engines used in automobiles and the like, a method for producing a caseless outer surface structure of an ignition coil has been studied (Japanese Patent Laid-Open No. 2009-182137). In such a manufacturing method, parts such as a coil assembly are arranged in a cavity in a mold, and an outer surface structure is formed by an overmolding method. For this reason, the resin structure formed around the coil assembly and the resin structure formed around the high-voltage terminal have their surfaces formed as one structure.

JP 2009-182137 A

  However, according to the technique of Patent Document 1, there is a problem that parts must be mounted inside the mold cavity, and the work at the time of mounting the parts becomes complicated. If attention is paid to the work at the time of conventional mounting, the work of providing a coil case as an outer surface structure and mounting a coil assembly or the like on this is made easier.

  Under such circumstances, it is also conceivable to mount a coil assembly or the like on a predetermined resin structure, and then attach the entire assembly to a mold cavity and overmold it. However, in this case, a boundary portion appears between the resin structure in which the coil assembly is mounted in advance and the resin structure formed by overmolding, and water or a humid atmosphere passes from here to the inside of the structure through the structure. There is a risk of intrusion.

  In view of the above problems, an object of the present invention is to provide an ignition coil for an internal combustion engine capable of ensuring a perfect sealing function even when a boundary between different structure surfaces is formed.

In order to solve the above problems, the present invention has the following configuration of an ignition coil for an internal combustion engine. That is, the high voltage terminal to which the output voltage of the coil assembly is applied, the high voltage side structure in which the high voltage terminal is accommodated in the structure made of the first resin material, and the second resin different from the first resin material at least a portion surrounding the overmolded coil side structure formed by bodies, a communication hole communicating to the high-voltage terminal attached to the high-pressure side structure formed of the resin material coil assembly and said high pressure side structure Plug boots and
The surface of the structure where the boundary between the high-pressure side structure and the coil-side structure appears is brought into contact with the plug boot and sealed.

  Preferably, the boundary is sealed between the coil assembly and the high voltage terminal in contact with the plug boot.

  Preferably, the boundary is accommodated in the plug hole.

  Preferably, a contact boundary portion where a boundary between the structure of either the high-voltage side structure or the coil-side structure and the plug boot appears outside is disposed outside the plug hole.

  Preferably, the second resin material is made of a polyamide resin.

  According to the ignition coil for an internal combustion engine according to the present invention, when the plug boot is mounted, the region including the boundary of the structure surface is sealed by the plug boot. For this reason, the ignition coil is spared from water entering through the boundary Y.

The figure which shows the internal structure of the ignition coil for internal combustion engines which concerns on embodiment. The figure which shows the external appearance of the ignition coil for internal combustion engines which concerns on embodiment. The figure explaining in detail the high voltage | pressure terminal of the ignition coil for internal combustion engines which concerns on embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an internal configuration of an ignition coil for an internal combustion engine according to the present embodiment. In this figure, a perspective view of an ignition coil for an internal combustion engine (hereinafter referred to as an ignition coil) is shown in (a), a front view of the ignition coil is shown in (b), and a side view of the ignition coil ( c). Please refer to these appropriately in accordance with the following description.

  As shown in the drawing, the internal structure of the ignition coil includes a coil assembly and a high-pressure side structure 131. Among these, the high pressure side structure 131 is made of a first resin material such as PBT (Polybutylene Terephthalate) or PPS (Poly Phenylene Sulfide), thereby forming a structure. However, the resins listed here are merely representative examples and are not limited thereto.

  In the high voltage side structure 131, a coil mounting portion and a high voltage terminal accommodating portion are integrally formed. Among these, the coil mounting part has a coil assembly mounted on its surface. The inside of the high voltage terminal accommodating portion is a cylindrical body, and a high voltage terminal (not shown) is provided at the inner end of the cylindrical body. The high-voltage terminal is electrically connected to the ignition plug of the internal combustion engine via a conductor (such as a spring) inserted into the cylindrical body.

  In the coil assembly, a secondary coil 120 and a primary coil (not shown) are combined, and these coils are arranged coaxially with respect to an internal I-shaped iron core (not shown). And the outer periphery iron cores 132 and 133 are arrange | positioned on the outer periphery of these components groups so that this may be enclosed. In this way, a closed path surrounding the inside and outside of the coil is formed around both the coils.

  In the present embodiment, an igniter 137 is provided in the coil assembly, and a plurality of terminals are arranged on a holder that holds the igniter 137. One of these terminals is connected to a battery power supply, the other is input with a drive signal, and the other is wired so as to match the GND potential. Furthermore, these terminals are appropriately connected to the terminal of the igniter 137, the energization terminal of the primary coil, and the like. On the other hand, the secondary coil has one end electrically connected to the high voltage terminal and the other end electrically connected to the GND side.

  When the coil assembly configured as described above receives the ignition signal, the primary current starts to rise, and generates a negative high voltage in response to the interruption of the ignition signal. Therefore, the negative high voltage is applied to the high voltage terminal and discharges the plug gap of the spark plug.

  The coil assembly and high-pressure side structure 131 described with reference to FIG. 1 is called an intermediate assembly assembled in a stage before being mounted in a mold cavity. After the intermediate assembly is set in the cavity of the mold, the second resin material is overmolded to form the coil side structure 140 of the ignition coil. As described above, in this embodiment, in order to avoid the trouble of directly attaching the coil assembly component to the mold cavity, the intermediate assembly is manufactured in advance and the procedure for mounting it to the mold cavity is taken. .

  As shown in FIG. 2, the coil-side structure 140 includes a covering portion 141 that directly covers a part of the coil assembly, and an outer layer portion 142 that covers a part of the high-pressure side structure (specifically, the high-pressure structure A part covering the body dish-like body from the outside), a shell-like part 143 in which the holder terminal is accommodated, and a flange part 144 in which a metal bush is embedded are integrally formed. Further, the structure (coil side structure) made of the second resin material surrounds a part of the high-pressure side structure, and a part of the high-pressure structure is exposed to form a surface portion (hereinafter referred to as structure). Called the body surface).

The surface of the structure refers to a portion where a surface is formed on each structure before the plug boot 150 is attached. Therefore, according to the present embodiment, each of the high-pressure side structure and the coil-side structure has a structure surface.

  As shown in FIG. 3A, in the region of the structure surface X where the high-voltage side structure and the coil-side structure are adjacent to each other, a boundary Y where both structures abut on the region is formed. In particular, in the ignition coil 100 according to the present embodiment, the first resin material and the second resin material are different materials. “Different” as used herein includes physical and chemical differences such as differences in physical properties of both or differences in composition of both, and is included if a cause that may cause separation between resins at boundary Y is recognized. It is. For example, when the two resins are compared, if the coefficients of thermal expansion are different, this is the cause of peeling at the boundary Y (difference in physical properties), and if a decrease in the binding force of both is recognized due to a difference in composition, this is the boundary. Caused by peeling at Y (difference in composition).

  Specifically, it is conceivable to use a polyamide resin (such as PA6) as the second resin material used in the present embodiment. Such a polyamide resin (Polyamide resin) is advantageous in that it generates less cracks around the iron core than PBT, PPS, and the like, and the buffer material around the iron core can be omitted. On the other hand, in the present embodiment, since the high-pressure side structure 131 is composed of PBT or the like, the difference in composition increases the risk of peeling at the boundary Y.

Therefore, in the ignition coil according to the present embodiment, as shown in FIG. 3B, the plug boot 150 is mounted on the cylindrical body forming the high-pressure side structure, and the inner wall of the plug boot 150 is the structure surface at the boundary Y. By being pressed, the boundary Y comes into contact with the inner wall of the plug boot and is sealed over the entire circumference. The plug boot 150 is provided with a communication hole 151 that communicates with the high-voltage terminal. When this is installed, the communication hole 151 can communicate with the high-voltage terminal. In the present embodiment, a constricted portion is provided on the inner wall of the plug boot 150, and this is brought into contact with the boundary Y so that the sealing function is perfect.

  As described above, according to ignition coil 100 according to the present embodiment, when plug boot 150 is attached, the region including boundary Y on the surface of the structure is sealed by plug boot 150. For this reason, the ignition coil 100 is spared from water and the like entering through the boundary Y.

In particular, in the present embodiment, the surface of the structure to be sealed is provided between the coil assembly and the high voltage terminal. That is, according to this embodiment, since the boundaries Y is accommodated in the inner wall of the plug boot 150 is because it is convenient to cause the seal boundary Y. Further, in the ignition coil 100, a sufficient distance from the end face of the plug boot 150 to the boundary Y is secured, and a seal structure can be easily provided on the inner wall of the plug boot 150. In this sense, the boundary Y is preferably arranged inside the plug hole of the internal combustion engine.

  Moreover, it is preferable that the boundary part Z where the end face of the plug boot 150 and the predetermined surface of the coil side structure abut is disposed outside the plug hole. According to this, since the distance between the boundary Y described above and the boundary portion Z above it is sufficiently secured, the dimensional margin for forming the seal structure is provided as before. In particular, when such a design is performed, the boundary portion Z is set to a sufficiently high position, so that the effect of reducing the risk of intrusion of water or the like can also be achieved. Here, the boundary part Z is a part where the end face of the plug boot 150 and the predetermined surface of the coil side structure abut. However, if the portion where the end face of the plug boot 150 and the predetermined surface of the high-pressure side structure abut is formed in addition to the boundary Y, this may be used as the boundary portion Z.

DESCRIPTION OF SYMBOLS 100 Ignition coil for internal combustion engines, 120 Secondary coil, 131 High pressure side structure 132 1st outer periphery iron core, 133 2nd outer periphery iron core, 137 igniter, 140 Coil side structure, 141 coating | coated part, 142 Outer layer part, 143 shell, 144 flange, 150 plug boot, 151 communication hole, X structure surface, Y boundary.

Claims (5)

A high voltage terminal to which the output voltage of the coil assembly is applied;
A high voltage side structure in which the high voltage terminal is accommodated in a structure made of a first resin material;
And the coil-side structure formed by overmolding around at least a portion of the coil assembly and the high-pressure side structure by a different second resin material and said first resin material,
A plug boot attached to the high-pressure side structure and formed with a communication hole communicating with the high-voltage terminal;
An ignition coil for an internal combustion engine, wherein a structure surface where a boundary between the high-pressure side structure and the coil-side structure appears is in contact with the plug boot and sealed.   2. The ignition coil for an internal combustion engine according to claim 1, wherein the boundary is sealed in contact with the plug boot between the coil assembly and the high-voltage terminal.   The ignition coil for an internal combustion engine according to claim 1 or 2, wherein the boundary is accommodated in a plug hole.   The contact boundary portion where the boundary between the structure of either the high-voltage side structure or the coil-side structure and the plug boot appears outside is disposed outside the plug hole. 3. An ignition coil for an internal combustion engine according to 3.   The ignition coil for an internal combustion engine according to any one of claims 1 to 4, wherein the second resin material is made of a polyamide resin.

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