JP6920076B2 - Noise suppression resistor - Google Patents

Description

The present invention relates to, for example, a noise suppression resistor mounted on a spark plug of an internal combustion engine such as an engine.

In a gasoline engine vehicle, a high-pressure current is passed through the spark plug of the engine ignition device to discharge the vehicle, and sparks are blown to the compressed mixed gas of gasoline and air in the cylinder to ignite the vehicle. Since the discharge requires a voltage of 10 kV or more, the gasoline engine vehicle is provided with an ignition coil for boosting the battery voltage (12 V). The ignition coil consists of a primary coil and a secondary coil housed in an insulating case, and a core (iron core) around which these primary coils and secondary coils are wound.

The engine ignition device is composed of a coil main body on which an IC chip or the like for ignition control via an ignition coil is mounted, a spring connected to a spark plug, a tubular insulating case for accommodating the spring, and the like. Further, in the engine ignition device, a noise prevention resistor is connected in series between the coil main body and the spring in order to suppress high frequency noise (noise) generated by electric discharge at the time of engine ignition.

Patent Document 1 describes an ignition coil for an internal combustion engine provided with a winding resistor for reducing discharge noise, which prevents the conductor winding of the winding resistor from being exposed and electrically conducts the metal cap and the conductor winding. In order to secure the above, a configuration is disclosed in which a ridge portion protruding inward is provided on the inner peripheral side of the side surface portion of the metal cap of the winding resistor, and the ridge portion and the conductor winding are brought into contact with each other. In Patent Document 1, one end face of the winding resistor press-fitted into the high-voltage tower portion abuts on the tip surface of the high-voltage output terminal, and the other end face hits a spring that electrically connects the high-voltage output terminal and the spark plug. I'm in contact.

Further, in Patent Document 2, a resistor for reducing discharge noise inserted into an ignition coil for an internal combustion engine is provided inside a cylinder of a high-pressure cylinder in order to prevent the resistor from falling off during assembly of the ignition coil. By providing an inwardly projecting portion that supports the lower surface, the lower surface of the resistor is supported by the inwardly projecting portion even during assembly, and the dimensional tolerance including the diameter dimension and the length dimension of the resistor with respect to the high pressure cylinder portion is large. Also discloses a technology to prevent it from falling out.

Japanese Unexamined Patent Publication No. 2016-134549 Japanese Unexamined Patent Publication No. 2011-35019

In Patent Document 1 described above, the inner diameter of the high-pressure tower portion on which the winding resistor is arranged is set to be larger than the outer diameter of the winding resistor, and a gap is provided between the winding resistor and the inner wall of the high-pressure tower portion. The winding resistor is press-fitted into the high-pressure tower portion. In such a structure in which the inner diameters are matched, poor contact may occur due to individual differences in resistors and towers (small differences in dimensions depending on the manufacturing lot). In addition, the structure in which a gap is interposed between the winding resistor and the inner wall of the high-voltage tower allows the resistor to be exposed to moisture and nitric acid, the bottom of the resistor cap and the coil body (high-voltage output terminal), and the structure. The contact with the spring may become unstable, which may cause poor continuity.

On the other hand, in the ignition coil described in Patent Document 2, the resistor is fixed by a high-voltage terminal and an inwardly projecting portion to protect the resistor from moisture and nitric acid, and the resistor, the coil main body (high-voltage output terminal), and the coil body (high-voltage output terminal), and The contact with the spring can be stabilized. However, when assembling the ignition coil, the resistor is press-fitted into the high-voltage tower, so a large compressive load is applied to the resistor, causing damage to the resistor and a load that exceeds the joint strength between the cap and the resistor element. This may cause problems such as unstable electrical continuity (poor connection).

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a noise prevention resistor that can prevent damage or the like when press-fitted into a high-pressure tower portion of an ignition coil of an internal combustion engine or the like. To provide.

In order to achieve the above object, the present invention is a noise prevention resistor in which cap terminals are attached to both ends of a substantially columnar resistor, and the cap terminal has a bottom surface portion, a side surface portion, and an opening portion. It has a bottomed tubular shape, and the side surface portion has an expansion portion that expands in a direction in which the diameter of the cap terminal gradually increases, and the expansion portion is divided into a plurality of portions in the circumferential direction of the cap terminal. A groove is formed, and the groove is formed only in the expansion portion of the side surface portion of the cap terminal, and the expansion portion has a shape in which the diameter of the cap terminal increases toward the opening. It is characterized by having flexibility to swing with respect to a compressive load from the outside.

The extension For example, the diameter of the cap pin in said opening, characterized in that a maximum. For example, of al, the groove is characterized in that it is formed at four positions in the circumferential direction of the extension portion. Also, for example, the resistor is characterized by a winding resistor formed by winding a resistance wire on the outer periphery of the core material was molded by bundling a fibrous insulating material.

Further, in order to achieve the above object, the mounting structure of the present invention is a mounting structure in which a noise prevention resistor is mounted in a case made of an insulating member and having a protrusion protruding inward in the circumferential direction on the inner wall surface. Therefore, the noise suppression resistor includes a resistor and cap terminals attached to both ends of the resistor, and the side surface portion of the cap terminal has a larger diameter of the cap terminal toward the opening. The noise prevention resistor is accommodated and supported in the case in a state where the expansion portion is in contact with the tip edge portion of the protrusion portion. ..

According to the present invention, when a noise prevention resistor is press-fitted into a high-voltage tower portion, an expansion portion provided at a cap terminal of the resistor reduces the load applied to the resistor during mounting to prevent damage to the resistor. At the same time, it is possible to prevent poor continuity between the cap terminal, the high voltage output terminal, and the spring.

The noise suppression resistor according to the embodiment of the present invention is shown, (a) is an external perspective view of the noise suppression resistor, and (b) is a resistor along the line of sight of AA'in (a). It is a cut sectional view. It is a flowchart which shows the manufacturing process of the noise prevention resistor which concerns on this Embodiment example in time series. It is sectional drawing which shows typically an example of the ignition coil for an engine which mounted the noise prevention resistor which concerns on this Embodiment example. It is a figure for demonstrating the state at the time of press-fitting and mounting of the noise prevention resistor in the ignition coil in comparison with the conventional example, and the Example of this Embodiment. It is a figure which shows the 1st shape example of the cap terminal of the resistor which concerns on this Embodiment example. It is a figure which shows the 2nd shape example of the cap terminal of the resistor which concerns on this Embodiment example. It is a figure which shows the 3rd shape example of the cap terminal of the resistor which concerns on this Embodiment example. It is a figure which shows the deformation example of the arrangement state in the high pressure tower part of a noise prevention resistor. It is external perspective view of the noise prevention resistor which concerns on the modification.

Hereinafter, examples of embodiments according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1A is an external perspective view of a noise prevention resistor (hereinafter, also simply referred to as a resistor) according to the embodiment of the present embodiment. Further, FIG. 1 (b) is a cross-sectional view of the resistor cut along the line of sight of AA'in FIG. 1 (a). The resistor 10 according to the embodiment of the present embodiment is a resistor in which a resistance wire 7 is wound around the outer circumference of a rod-shaped (cylindrical) core material 5 formed by bundling fibers made of a fibrous insulator, for example, an insulator such as glass. It is configured to include an element (also referred to as a resistor) 2 and cap terminals 3a and 3b attached to both ends of the resistance element 2 by press fitting or the like and electrically connected to the end of the resistance wire 7. ..

The resistor 10 is a resistor that functions as a noise prevention resistor, that is, is mounted on an engine ignition device and functions as a noise filter that effectively suppresses radiated noise such as ignition noise generated when the engine is ignited. If it is a resistor that can achieve such a purpose, for example, a winding resistance element formed by winding a resistance wire such as Ni-Cr around a core material, or a ceramic formed by forming powders such as tin oxide and antimony oxide into a columnar shape. A resistor having a cap terminal attached to a resistance element or a metal film resistance element obtained by trimming a metal plating film such as electroless Ni can be used.

The resistance wire 7 wound around the outer circumference of the core material 5 is, for example, a metal wire such as a nickel / iron (Ni—Fe) wire, a nickel (Ni) wire, or a chromium (Cr) wire, depending on the resistance value of the resistor. To select. Here, the resistance wire 7 having a wire diameter of about several tens of μm (for example, 50 to 60 μm) is wound around the core material 5 at a narrow pitch. The metal wire may be used as it is as the resistance wire 7, or a coated conductor wire having a resin coating formed on the surface of the metal wire may be used.

On the other hand, as the core material 5, for example, a core material made by bundling a large number of fibers made of an insulating material such as glass, ferrite, resin, or alumina is used. Glass fiber bundles are suitable from the viewpoint of cost and high heat resistance. The glass fiber bundle is a bundle obtained by combining a plurality of glass fibers and has a fiber diameter of several μm to several tens of μm. Therefore, if the glass fiber is conveyed in a long state before cutting, the shape of the core material cannot be maintained and the glass fiber is curved. Therefore, the glass fiber is impregnated with an epoxy resin, a silicone resin, or the like and heat-cured to maintain the shape.

The cap terminals 3a and 3b attached to both ends of the resistance element have a bottomed tubular shape having openings, are made of a conductive metal such as iron or stainless steel, and the surface thereof is plated with copper, nickel or the like. ing. As shown in FIG. 1 (b), the cap terminals 3a and 3b have a bottom surface portion 11a and 11b which are the end portions in the axial direction of the resistor 10 and a side surface portion formed in a wall shape along the periphery of the bottom surface portion. It is composed of 13a and 13b and openings 15a and 15b for press-fitting cap terminals into both ends of the resistor 2.

Expansion portions 17a and 17b are provided on the side surface portions 13a and 13b of the cap terminal, and flat portions 19a and 19b continuous with the expansion portions 17a and 17b and flat in the circumferential direction are provided on the openings 15a and 15b sides. ing. The diameter D (maximum value of the diameter of the cap terminal) of the expansion portions 17a and 17b may be, for example, the inner wall of the high-pressure tower portion described later + 0.1 mm or more.

FIG. 2 is a flowchart showing the manufacturing process of the noise prevention resistor according to the embodiment of the present embodiment in chronological order. First, the core material is formed in step S11 of FIG. Here, for example, glass fibers having a fiber diameter of about several μm are bundled, impregnated with an epoxy resin or a silicone resin, and formed into a long rod shape to form a core material. In the following step S13, resistance wires such as nickel / iron (Ni-Fe) wire, nickel (Ni) wire, chromium (Cr) wire, and nickel / chromium (Ni-Cr) wire are specified on the outer peripheral surface of the core material. Wrap continuously at the pitch of. The resistance value of the resistor is adjusted according to the type of wire and the winding pitch.

In step S15, the core material around which the resistance wire is wound is dried to cure the resin. In step S17, for example, an epoxy resin or a silicon resin is applied and coated on the outer peripheral surface of the core material that has been dried and cured by winding the resistance wire as described above. Since the purpose of the resin coating is to fix the resistance wire, the resin coat to be formed may be thick enough to hide the resistance wire. Then, in step S19, the resin coat is cured.

In step S21, the resistance wire is wound as described above, and the long core material coated with the resin is cut to a predetermined size together with the resistance wire by a cutter or the like. As a result, individual pieces of winding resistance elements (resistors) are manufactured. In step S23, cap terminals are attached to both ends of the winding resistance element. For example, the cap terminal is mechanically pushed in the axial direction from both ends of the winding resistance element, temporarily fixed, and then the side surface portion of the cap terminal excluding the expansion portion and the flat portion is pressed from the outer peripheral surface thereof. By deforming (caulking), the resistance wire and the cap terminal are electrically conducted.

That is, the resistance wire is cut at the same time when the glass fiber is cut into individual pieces, and the end thereof is accommodated in the cap terminal and fixed by caulking. The cap terminal is made of a conductive metal such as iron or stainless steel, and its surface is plated with copper, nickel or the like. The cap terminal may be press-fitted (fitted) to both ends of the winding resistance element.

In step S25, the winding resistor produced in the above step is immersed in a tank filled with, for example, urethane resin, epoxy resin, etc., dried and cured to protect the resistance wire and the opening of the cap terminal. Form a film. As a method for forming the protective film, it may be applied or sprayed with a brush or the like. Further, the protective film may be formed if necessary. Then, in step S27, which is the final step, inspections such as appearance image inspection and resistance value inspection of the manufactured resistor are performed.

The method for curing the resin or the like in step S15 or the like may be any of curing at room temperature, heat curing (for example, 100 to 150 ° C.), or curing by ultraviolet irradiation. Further, from the viewpoint of shortening the drying time, the resin of the protective film formed on the entire outer surface of the resistor may be limited to the quick-drying urethane resin.

FIG. 3 is a cross-sectional view schematically showing an example of an ignition coil for an engine (internal combustion engine) on which the noise prevention resistor according to the present embodiment is mounted. As shown in FIG. 3, the ignition coil 20 is a coil portion 30 in which a boosting coil (ignition coil) 26 or the like is housed in an insulating case 21 made of a thermoplastic resin or the like, and a noise prevention resistor 10 or the like protruding from the coil portion 30. It is provided with a high-pressure tower unit 40 in which the coil is stored. In FIG. 3, the joint portion and the like which are arranged in the lower part of the high-pressure tower portion 40 and are inserted into the plug holes of the engine block are not shown.

The boost coil 26 housed in the coil portion 30 has a configuration in which a primary coil 22 and a secondary coil 24 are wound around a core (iron core) 23, and the primary and secondary coils are magnetically coupled to ignite. Generates high voltage for. Further, the control unit 25 functions as an igniter that controls ignition timing, power control, etc. via the boost coil 26, and is composed of, for example, an IC chip.

Inside the high-voltage tower unit 40, a high-voltage output terminal 29 electrically connected to the step-up coil 26 via the connection terminal 27 is arranged on the coil unit 30 side. The insulating case 21 is filled with a resin 31 that seals the primary coil 22, the secondary coil 24, and the like. By arranging the high-voltage output terminal 29 along the inner diameter of the top of the high-voltage tower portion 40 so as to close the top, the resin 31 filling the insulating case 21 is prevented from flowing into the high-voltage tower portion 40. There is.

A coil-shaped spring 33 extending in the axial direction is inserted into the joint portion (not shown) of the ignition coil 20. One end (cap terminal 3b) of the resistor 10 housed in the high-voltage tower portion 40 abuts on one end surface of the high-voltage output terminal 29, and the other end (cap terminal 3a) of the resistor 10 is a spring 33. It is in close contact with the upper end. Therefore, the boost coil 26 is electrically connected to a spark plug (not shown) connected to the lower end of the spring 33 via the high voltage output terminal 29 and the resistor 10.

That is, a high voltage ignition timing signal of 10 kV or more induced by the step-up coil 26 of the coil portion 30 is applied to the spark plug via the resistor 10 and the spring 33, and is between the center electrode and the ground electrode of the spark plug. Sparks fly into the gap, igniting a compressed mixture of gasoline and air in the engine coil.

FIG. 4 is a diagram for explaining a state of the ignition coil when the noise prevention resistor is press-fitted and mounted (when the ignition coil is assembled) in comparison with the conventional example and the embodiment of the present embodiment. In each of the examples, the inner wall of the cylinder of the high-pressure tower portion of the ignition coil is provided with a protrusion 41 projecting toward the inside of the cylinder in order to support the accommodated resistor.

FIG. 4A is a cross-sectional view schematically showing a state in which a resistor is press-fitted into the cylinder of a conventional high-pressure tower portion. When the resistor 50 is press-fitted into the cylinder downward from the upper surface side of the high-pressure tower portion 40, the force indicated by the arrow is applied to the resistor 50, so that the cap 53a descends along the inner wall 45a of the cylinder. , The circumferential edge portion 52a of the tip surface (bottom surface) 51a of the cap abuts on the protrusion 41. Then, the state in which the resistor 50 is supported by the protrusion 41 is maintained.

FIG. 4B is a detailed perspective view of the portion shown by the broken line B in FIG. 4A. The resistor 50 has a structure in which the entire surface of the side surface portion 55 of the cap 53a is in close contact with the wall surface on the tip end side of the main body portion of the resistor 50 along the circumferential direction thereof. Therefore, when the resistor 50 abuts on the protrusion 41 when the resistor 50 is press-fitted into the ignition coil, the peripheral edge portion 52a (shaded portion of FIG. 4B) of the cap tip surface 51a is shown in FIG. 4B. The impact force (reaction force) indicated by the white arrow acts. This impact force is absorbed by the resistor 50 or the like while propagating to the main body or the like of the resistor 50 in close contact with the cap 53a. Therefore, the resistor 50 may be damaged due to the impact force received.

On the other hand, FIG. 4C is a cross-sectional view schematically showing a state in which the noise prevention resistor according to the embodiment of the present embodiment is press-fitted into the cylinder of the high-voltage tower portion. The cap terminal 3a of the resistor 10 according to the present embodiment gradually expands outward in the axial direction of the resistor as the side surface portion 13a toward the opening 15a, and the diameter of the cap terminal gradually increases. Has. Therefore, when the resistor 10 is press-fitted into the cylinder from the upper surface side of the high-pressure tower portion, the force indicated by the arrow is applied to the resistor 10, and the expansion portion 17a is provided in the cylinder of the high-pressure tower portion in the circumferential direction thereof. The resistor 10 is supported inside the cylinder while abutting against the tip edge portion of the protruding portion 41 and maintaining the state of contact with the tip edge portion.

FIG. 4D is a detailed perspective view of the portion shown by the broken line C in FIG. 4C. As described with reference to FIG. 4 (b), the conventional resistor 50 has a cap when the resistor is press-fitted into the high-pressure tower portion and when the resistor is in a supported state in the cylinder thereafter. The circumferential edge 52a of the tip surface is in surface contact with the protrusion 41 in the cylinder. On the other hand, the cap terminal 3a of the resistor 10 according to the embodiment of the present embodiment is a portion of the dotted line 44 whose expansion portion 17a is virtually drawn in FIG. 4 (d), and is a protrusion 41 in the cylinder. Is in line contact with. Therefore, an external force (reaction force from the protrusion 41) indicated by a white arrow in FIG. 4D acts on the portion shown by the dotted line 44 due to a collision with the protrusion 41 or the like on the expansion portion 17a. , The load at the time of press-fitting is concentrated on the expansion portion 17a.

In the resistor 10 according to the embodiment of the present embodiment, the side surface portion of the cap terminal is not in close contact with the outer peripheral wall surface of the resistor at the portion where the expansion portion 17a is provided, and the edge portion 37 of the opening portion 15a is a free end. It has become. Therefore, the expansion portion 17a where the load is concentrated at the time of collision with the protrusion 41 exhibits flexibility, and the edge portion 37 is slightly narrowed toward the center side of the shaft, for example, over the entire circumference thereof. Deform. As a result, the expansion portion 17a functions as a cushioning material when press-fitting and mounting, and absorbs vibrations and shocks generated when press-fitting and mounting, and the impact force on the resistor is relaxed.

Further, in the resistor 10 according to the embodiment of the present embodiment, as shown in FIGS. 4C and 4D, the reaction force from the protrusion 41 at the time of press-fitting and mounting is oblique to the expansion portion 17a. It works. Therefore, compared to the conventional resistor 50 in which the impact force due to press-fitting or the like is directly transmitted, in the resistor 10 according to the embodiment of the present embodiment, the impact load (compressive load) is dispersed by the expansion portion 17a, so that the load can be increased. Suppression effect and impact resistance are improved.

Further, in the resistor 10 according to the embodiment of the present embodiment, the winding resistance element and the cap terminal 3a are fixed by caulking the side surface portion of the cap terminal, but the cross-sectional shape of the side surface of the cap terminal is changed by caulking. , For example, it is assumed that the shape is other than a circle such as a hexagon or an octagon. In the conventional resistor mounting structure, when the cross-sectional shape of the side surface portion of the cap terminal is not circular, it is difficult to bring it into close contact with the inner wall of the cylindrical high-pressure tower portion. In No. 10, even if the side surface portion of the cap terminal 3a has a flat surface portion (caulking mark), the expansion portion 17a having a circular cross-sectional shape can be brought into close contact with the inner wall (projection portion) of the high-pressure tower portion. Therefore, there is no possibility that the resistor 10 is exposed to moisture (humidity) and nitric acid.

Next, the shape of the cap terminal of the resistor according to the present embodiment will be described with reference to FIGS. 5 to 7. In addition, each of FIGS. 5 to 7 is composed of a side view of the cap terminal and a top view when viewed from the opening side.

FIG. 5 shows an example of the shape of a cap terminal provided with an expansion portion (also referred to as a protruding portion) inclined toward the opening. The cap terminal of FIG. 5A has a shape in which the extension portion 65a toward the opening 67a extends outward in a straight line in cross section. On the other hand, the cap terminal of FIG. 5B has a shape in which the expansion portion 65b toward the opening 67b is inclined (curved) outward, and the cap terminal of FIG. 5C has an expansion toward the opening 67c. The portion 65c is inclined (curved) inward and has a rounded shape.

As shown in FIG. 5A, the height H1 of the cap terminal in the central axis direction is, for example, 2.5 mm to 5 mm, and the height H2 of the expansion portion is, for example, 1 mm to 3.5 mm. The height dimension is not limited to this, and the height H2 of the expansion portion may be about 2/3 of the height H1 of the cap terminal. Further, the position, height, and diameter of the expansion portion can be arbitrarily changed depending on the structure of the high-pressure tower portion on which the resistor is mounted.

FIG. 6 is an example of the shape of a cap terminal provided with an expansion portion and a flat portion formed in the vicinity of the opening. The cap terminal of FIG. 6A has a shape in which the cross section of the expansion portion 75a extends linearly outward toward the opening 77a, and a flat portion 78a continuous with the expansion portion 75a is provided on the opening 77a side. I have. The cap terminal of FIG. 6B has a shape in which the expansion portion 75b toward the opening 77b is inclined (curved) outward, and the opening 77b side is provided with a flat portion 78b continuous with the expansion portion 75b. ing.

The cap terminal of FIG. 6C has a rounded shape in which the expansion portion 75c toward the opening 77c is inclined (curved) inward, and the opening 77c side is flat and continuous with the expansion portion 75c. The part 78c is provided. Further, the cap terminal of FIG. 6D has a shape in which the outer side of the expansion portion 75d extends linearly toward the opening 77d, but the inner side extends parallel to the central axis direction. Here, the height of the flat portion 78d continuous with the expansion portion 75d on the opening 77d side in the axial direction is made higher than in the other examples shown in FIGS. 6A to 6C, and is directed toward the axial center. The wall thickness is made thicker than those in FIGS. 6 (a) to 6 (c). In FIG. 6D, the inside of the expansion portion 75d and the flat portion 78d (the inner surface side of the cap terminal) are continuous and identical surfaces.

In the shape example shown in FIG. 6, by providing a flat portion continuous with the expansion portion, it is possible to prevent the cap terminal from being distorted by a compressive load toward the axial center of the cap terminal, and further, when press-fitting into the high-pressure tower portion. The positioning and mounting of the resistor in the above is facilitated. As shown in FIG. 6A, for example, the height H3 of the flat portion in the axial direction of the cap terminal is set to about 1/5 of the height H2 of the expansion portion.

FIG. 7 is an example of the shape of the cap terminal with the extended portion protruding. The cap terminal of FIG. 7A has a shape in which a part of the side surface portion 83a is projected outward in the circumferential direction to form an expansion portion 85a while having the same inner diameter of the opening portion 87a and the bottom surface portion 81a. The cap terminal of FIG. 7B includes an expansion portion 85b in which a part of the side surface portion 83b is projected outward in the circumferential direction, and a side surface portion 83b is provided on the upper portion of the expansion portion 85b on the opening 87b side. It has a shape in which a constriction 88 is provided, which is recessed inward in the circumferential direction and has an inner diameter smaller than the inner diameter of the bottom surface portion 81b. The constriction 88 has a role of electrically conducting the resistance wire and the cap terminal instead of caulking.

Similar to the cap terminal of FIG. 7 (a), the cap terminal of FIG. 7 (c) has the same inner diameter of the opening 87c and the bottom surface 81c, and a part of the side surface 83c is widely projected in the axial direction. It has a shape in which the expansion portion 85c is formed.

As described above, in the noise prevention resistor according to the embodiment of the present embodiment, the side surface portions of the cap terminals mounted on both ends of the resistance element gradually expand outward in the axial direction toward the opening, and the diameter of the cap terminal becomes larger. Since it has an expansion portion that gradually increases, the expansion portion comes into contact with the tip edge portion of the cylinder inner wall protrusion portion of the high pressure tower portion when the resistor is press-fitted into the high pressure tower portion or the like. At that time, by providing the expansion portion, the load (pressure) applied to the resistor at the time of mounting is reduced, so that the resistor can be prevented from being damaged. At the same time, since the resistor is firmly fixed to the inner wall of the high-voltage tower, the contact between the cap terminal, the coil body (high-voltage output terminal), and the spring is stable, and poor continuity can be prevented.

Also, when fixing the cap terminals to both ends of the noise prevention resistor by caulking, even if the cross section of the side surface of the cap terminal has a shape other than a circle, the cap terminal is cylindrical due to the expansion part whose cross section remains circular. It can be brought into close contact with the inner wall of the high-pressure tower portion of the above, and it is possible to suppress poor conductivity of the resistor and improve moisture resistance, acid resistance and corrosion resistance.

Furthermore, the shape of the expansion part is such that the diameter of the cap terminal gradually increases toward the opening, so that there is an individual difference (dimensional tolerance) in the inner diameter of the cylinder part of the high-pressure tower part on which the noise prevention resistor is mounted. Even if there is, the cap terminal moves in the axial direction of the cylinder portion at the time of press-fitting and stops at a position that matches the inner diameter of the cylinder portion. As a result, the presence of the expansion portion cancels out individual differences in the inner diameter of the cylinder portion of the high-pressure tower portion, and the loss of moisture resistance and airtightness due to poor connection or the like can be avoided.

The present invention is not limited to the above-described embodiment, and various modifications are possible. As an example of mounting the noise prevention resistor, in the example shown in FIG. 3, a high-voltage output terminal 29 is arranged on the top of the high-voltage tower portion 40 so as to close the top along the inner diameter of the cylinder portion, and the insulating case 21 is provided. The resin 31 to be filled is prevented from flowing into the high-pressure tower portion 40.

That is, FIG. 3 shows a state in which the noise prevention resistor is arranged in the high-voltage tower unit 40 in a state where it is not embedded with resin, but when the configuration is such that the high-voltage output terminal is not provided, the high-voltage tower unit The resin filled in the case also enters around the resistor in the cylinder. In that case, as shown in FIG. 8, when the resistor is mounted on the high-pressure tower portion (when the ignition coil is assembled), the resistor 10 is strongly pushed downward of the cylinder, so that the expansion portion 17a of the cap terminal 3a has a high pressure. Since it is pressed against the protrusion 41 provided on the inner wall of the tower portion and fits into the tower portion, the expansion portion 17a can surely prevent the resin 31 from leaking to the lower side of the protrusion 41 or the like.

Further, in the above-described embodiment, cap terminals having expansion portions 17a and 17b are attached to both ends of the noise prevention resistor 10, but the present invention is not limited to this, and the expansion portion is provided only at one end of the resistor. A noise prevention resistor may be provided with a cap terminal having a cap terminal attached and a cap terminal having no expansion portion provided at the other end. As a result, it is possible to provide a resistor having a simplified structure by providing an expansion portion only on the end portion side that receives an impact at the time of press-fitting.

Further, in the noise prevention resistor 10 according to the above embodiment, the expansion portions 17a and 17b are continuously formed over the entire circumference of the cap terminal, but the present invention is not limited to this. For example, like the noise prevention resistor 60 shown in FIG. 9, expansion portions 97a and 97b are formed in a plurality of directions in the circumferential direction of the cap terminals 93a and 93b, and they are arranged so as to be symmetrical when viewed from the axial direction. You may. By doing so, when an impact is received at the time of mounting or the like, the expansion portions 97a and 97b are easily swung, and the impact force on the resistor is further relaxed by efficient distribution of the load (compressive load).

2 Resistance element (resistor)
3a, 3b, 93a, 93b Cap terminal 5 Core material 7 Resistance wire 10, 50, 60 Noise prevention resistor 11a, 11b, 61a to 61c, 71a to 71d, 81a to 81c Bottom part 13a, 13b, 63a to 63c, 73a -73d, 83a-83c Side surface portions 15a, 15b, 67a-67c, 77a-77d, 87a-87c Openings 17a, 17b, 65a-65c, 75a-75d, 85a-85c, 97a, 97b Expansion portions 19a, 19b, 78a to 78d Flat part 20 Ignition coil 21 Insulation case 22 Primary coil 23 Core (iron core)
24 Secondary coil 25 Control unit 26 Boost coil (ignition coil)
27 Connection terminal 30 Coil part 31 Resin 33 Spring 37 Edge end 40 High-voltage tower part 41 Protrusion 45a Inner wall of cylinder 52a Circumferential edge 88 Constriction

Claims (4)

It is a noise prevention resistor with cap terminals attached to both ends of a substantially cylindrical resistor.
The cap terminal has a bottomed tubular shape having a bottom surface portion, a side surface portion, and an opening portion, and the side surface portion has an expansion portion that expands in a direction in which the diameter of the cap terminal gradually increases, and the side portion thereof. A groove is formed to divide the expansion portion into a plurality of parts in the circumferential direction of the cap terminal .
The groove is formed only in the expansion portion of the side surface portion of the cap terminal.
The expansion portion has a shape in which the diameter of the cap terminal increases toward the opening, and has flexibility to swing with respect to a compressive load from the outside . .. The noise prevention resistor according to claim 1 , wherein the expansion portion has a maximum diameter of the cap terminal at the opening. The noise prevention resistor according to claim 1 or 2 , wherein the grooves are formed at four locations in the circumferential direction of the expansion portion. Any one of claims 1 to 3 , wherein the resistor is a wound resistor formed by winding a resistance wire around the outer periphery of a core material formed by bundling fibrous insulators. The noise suppression resistor described in.

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