Resistance

Abstract

To provide a resistor capable of improving heat dissipation property.SOLUTION: A resistor 1 includes a resistance body part 2, and a resin part 3 covering the resistance body part 2. The resin part 3 has a heat dissipation fin 32.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resistor. [Background technology]

[0002] Patent Document 1 discloses a cement resistor that includes a case, a resistor placed in the case, and a cement material that is filled in the case and seals the resistor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-38275 Summary of the Invention [Problem to be solved by the invention]

[0004] In the cement resistor described in Patent Document 1, heat generated in the resistor is transmitted through the cement and the case in order, and then dissipated to the outside of the cement resistor, but there is room for improvement in terms of improving heat dissipation.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resistor that can improve heat dissipation properties. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a resistor comprising a resistor body and a resin part covering the resistor body, the resin part having heat dissipation fins. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a resistor that can improve heat dissipation properties. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of a resistor according to the first embodiment. [Figure 2] 1 is a cross-sectional view perpendicular to the longitudinal direction of a resistor according to a first embodiment. [Figure 3] 1 is a cross-sectional view parallel to the longitudinal direction of a resistor according to a first embodiment. [Figure 4] 3 is a schematic enlarged view of a part of a cross section of a resin portion in the first embodiment. FIG. [Figure 5] FIG. 10 is a perspective view of a resistor according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view perpendicular to the longitudinal direction of a resistor according to a second embodiment. [Figure 7] FIG. 10 is a perspective view of a resistor according to a third embodiment. [Figure 8] FIG. 10 is a front view of a resistor according to a third embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a resistor according to a third embodiment taken at the center position in the longitudinal direction. [Figure 10] FIG. 10 is a cross-sectional view parallel to the longitudinal direction of a resistor according to a third embodiment. [Figure 11] FIG. 11 is an exploded perspective view of a resistor body and a pair of inserts in a third embodiment. [Figure 12] FIG. 11 is a perspective view showing a fixed mold, a movable mold, a slide core, and a resistance assembly before mold clamping in a third embodiment. [Figure 13] FIG. 11 is a cross-sectional view showing a fixed mold, a movable mold, a slide core, and a resistor assembly after mold clamping in a third embodiment. [Figure 14] FIG. 10 is a perspective view of a resistor according to a fourth embodiment. [Figure 15] FIG. 10 is a cross-sectional view perpendicular to the longitudinal direction of a resistor according to a fourth embodiment. [Figure 16] FIG. 13 is a cross-sectional view showing how a resistor body is attached to a fixed mold according to a fourth embodiment. [Figure 17]FIG. 13 is a cross-sectional view showing a state in which a movable mold is brought close to a fixed mold on which a resistor main body is provided in a fourth embodiment. [Figure 18] FIG. 10 is a cross-sectional view showing a clamped fixed mold and movable mold, and a resistor main body in a fourth embodiment. [Figure 19] FIG. 11 is a perspective view of a resistor according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 4. The embodiment described below is shown as a preferred specific example for carrying out the present invention, and although various technically preferable technical matters are specifically exemplified, the technical scope of the present invention is not limited to this specific embodiment.

[0010] Fig. 1 is a perspective view of a resistor 1 according to this embodiment. Fig. 2 is a cross-sectional view perpendicular to the longitudinal direction of the resistor 1. Fig. 3 is a cross-sectional view parallel to the longitudinal direction of the resistor 1. Fig. 3 illustrates a state in which the resistor 1 is attached to a circuit board 11.

[0011] The resistor 1 includes a resistor body 2 formed long in one direction and a resin part 3 in which the resistor body 2 is embedded. Hereinafter, the longitudinal direction of the resistor body 2 will be simply referred to as the longitudinal direction X. The side closer to the center of the resistor body 2 in the longitudinal direction X will be referred to as the inner longitudinal side, and the side farther from the center of the resistor body 2 in the longitudinal direction X will be referred to as the outer longitudinal side.

[0012] The resistor body 2 includes a resistor element 21 and a pair of cap electrodes 22 fitted to both ends of the resistor element 21. In this embodiment, the resistor element 21 is a so-called wire-wound resistor element, and includes an electrically insulating core material 211 and a winding 212 wound helically around the outer periphery of the core material 211. The core material 211 is formed by forming an electrically insulating material, such as ceramic, into a cylindrical shape. The winding 212 is made of a conducting wire, such as nichrome wire. Note that the resistor element 21 is not limited to a wire-wound resistor element, and may be a ceramic resistor element without a winding 212, such as a cylindrically formed conductive ceramic.

[0013] The cap electrode 22 is made of a conductive metal or the like. The cap electrode 22 has a disk-shaped bottom 221 perpendicular to the longitudinal direction X and a cylindrical side 222 extending inward in the longitudinal direction from the periphery of the bottom 221, and is formed in a cap shape. The side 222 of the cap electrode 22 is open on the side opposite the bottom 221. The pair of cap electrodes 22 are fitted to both ends of the resistance element 21 in the longitudinal direction X. When fitted to the resistance element 21, the side 222 of the cap electrode 22 is in electrical contact with the winding 212 of the resistance element 21, thereby electrically connecting the cap electrode 22 to the winding 212. Note that when the pair of cap electrodes 22 are fitted to the resistance element 21, the cap electrodes 22 and the winding 212 may be connected by welding or the like.

[0014] The flange portion 23 is formed so as to extend from an end of the side portion 222 of the cap electrode 22 opposite the bottom portion 221 toward the outer periphery of the side portion 222. The flange portion 23 is formed in a plate shape having a thickness in the longitudinal direction X. In this embodiment, the flange portion 23 is formed integrally with the cap electrode 22. For example, the cap electrode 22 and the flange portion 23 can be formed simultaneously by pressing a single plate. However, this is not limitative, and the flange portion 23 and the cap electrode 22 may be formed separately. In this case, the flange portion 23 and the cap electrode 22 may be connected by, for example, welding or the like.

[0015] The flange portion 23 has exposed terminals 20 exposed from the resin portion 3. As shown in FIG. 3 , the exposed terminals 20 are inserted into through holes 110 in the circuit board 11 and connected to the circuit board 11 using solder 12 or the like. In this embodiment, the direction in which the tips of the exposed terminals 20 face is referred to as the vertical direction Z, and one side of the vertical direction Z to which the tips of the exposed terminals 20 face is referred to as the lower side, and the opposite side is referred to as the upper side. Note that the expressions "upper" and "lower" are used for convenience and do not limit the orientation of the resistor 1 relative to the vertical direction when the resistor 1 is in use, for example. However, in this embodiment, it is assumed that the resistor 1 is used in an orientation in which the vertical direction Z is the vertical direction, the upper side of the vertical direction Z is the upper side in the vertical direction, and the lower side of the vertical direction Z is the lower side in the vertical direction. The resistor body 2, except for the exposed terminals 20, is embedded in the resin portion 3.

[0016] The resin part 3 has a rectangular columnar resin body 31 formed long in the longitudinal direction X and having the resistor body 2 embedded therein, and a plurality of heat dissipation fins 32 protruding from the resin body 31. In this embodiment, the resin part 3 is a single resin molded product, integrally including the resin body 31 and the plurality of heat dissipation fins 32. The resin part 3 is a molded resin in which the resin body 31 and the plurality of heat dissipation fins 32 are molded simultaneously by injecting molten resin into a cavity with the resistor body 2 placed in a mold and allowing it to harden.

[0017] The plurality of heat dissipation fins 32 protrude from the tip side (i.e., the lower side) of the exposed terminal portion 20 to the opposite side (i.e., the upper side). The heat dissipation fins 32 are long in the longitudinal direction X and are continuously formed from one end of the resin portion 3 in the longitudinal direction X to the other end. The spaces between adjacent heat dissipation fins 32 are open on both sides in the longitudinal direction X. The plurality of heat dissipation fins 32 are arranged at equal intervals and are formed parallel to each other. The length of the heat dissipation fins 32 protruding from the resin main body portion 31 is longer than their thickness.

[0018] FIG. 4 is a schematic diagram showing an enlarged portion of the cross section of the resin portion 3. As shown in FIG. 4, the resin portion 3 is made of an electrically insulating base resin 301 containing thermally conductive filler 302. The base resin 301 is made of an electrically insulating resin such as PPS (polyphenylene sulfide) resin or epoxy resin. The filler 302 can be made of, for example, metal powder or ceramic powder, and more specifically, powder of aluminum oxide, boron nitride, aluminum nitride, or the like. Note that, for convenience, the filler 302 is shown as a circle in FIG. 4, but the shape of the filler 302 is not limited to this.

[0019] By including the thermally conductive filler 302 in the resin portion 3, the thermal conductivity of the entire resin portion 3 is improved, and the temperature inside the resistor 1 is prevented from rising to a high temperature. In this embodiment, the thermal conductivity of the resin portion 3 is equal to or higher than that of cement, for example, 2 W / (m·K) or higher, and preferably 3 W / (m·K) or higher. The thermal conductivity of the resin portion 3 can also be 10 W / (m·K) or lower.

[0020] A typical cement resistor is constructed by filling a case with cement, which adheres tightly to the case. The resistor 1 of this embodiment adheres tightly to the resin part 3 and does not have a case to house the resin part 3. This prevents the resistor 1 from becoming large. When using the resistor 1, it is possible to assemble the resistor 1 into a case manufactured separately from the resistor 1. Even in this case, the resistor 1 is removably attached to the case, but the resistor 1 itself, which does not have a case, is formed small.

[0021] The resistor 1 may be disposed, for example, in the engine compartment of an automobile. In this case, the resistor 1 may be disposed in a motor wiring connecting a stator coil of the motor to a terminal block of the motor, forming a snubber circuit for suppressing surge voltage. When the resistor 1 is disposed in a high-temperature environment such as an engine compartment, the ambient temperature of the resistor 1 becomes high, and the resistor 1 is required to have high heat dissipation properties. The resistor 1 of this embodiment is therefore suitable for use. When the resistor 1 is attached to the circuit board 11, the lower surface of the rectangular columnar resin portion 3 faces the circuit board 11. Heat from the resistor 1 is dissipated through the resin portion 3, particularly from the portion where the heat dissipation fins 32 are provided, into the air surrounding the resistor 1, and is also dissipated by heat transfer to the circuit board 11.

[0022] The resistor 1 may be mounted on a mounting member other than the circuit board 11. In this case, for example, if the surface of the mounting member that comes into contact with the resistor 1 has a non-planar shape, such as a curved surface, the surface of the resin part 3 that comes into contact with the mounting member may be shaped to conform to the non-planar shape. The resin part 3 may also have a shape other than a rectangular columnar shape.

[0023] Next, an example of a method for manufacturing the resistor 1 of this embodiment will be described. In the method for manufacturing the resistor 1 of this embodiment, the resistor body 2 is manufactured and placed in a mold. Two molds can be used, each of which moves forward and backward in the direction in which the exposed terminals 20 protrude from the resistor body 2 (i.e., the vertical direction Z). The lower mold has an insertion hole for inserting the exposed terminals 20, and the resistor body 2 is placed in the lower mold by inserting the exposed terminals 20 into the lower mold. The upper mold has recesses and protrusions for forming a plurality of heat dissipation fins 32. After the resistor body 2 is placed in the mold, the resin portion 3 is molded integrally with the resistor body 2 by insert molding, in which molten resin is injected into the cavity and hardened. In this manner, the resistor 1 of this embodiment can be manufactured.

[0024] The plurality of heat dissipation fins 32 may be provided with a draft angle to facilitate removal from the upper mold later when molding the resin part 3. For example, the heat dissipation fins 32 may be formed with a slope on all surfaces other than the upper surface so that the thickness and length in the longitudinal direction X become smaller toward the upper side.

[0025] (Functions and Effects of the First Embodiment) In the resistor 1 of this embodiment, the resin portion 3 has heat dissipation fins 32. This increases the surface area of ​​the resistor 1, improving the heat dissipation performance of the resistor 1. Furthermore, by providing the heat dissipation fins 32 on the resin portion 3, the heat dissipation fins 32 can be easily formed by molding. Furthermore, by providing the heat dissipation fins 32 on the resin portion 3, the degree of freedom in forming the heat dissipation fins 32 is improved.

[0026] Moreover, the heat dissipation fins 32 are formed long in the longitudinal direction X. This makes it easier to increase the surface area of ​​the resin portion 3, thereby improving the heat dissipation performance of the resistor 1.

[0027] The resin portion 3 also has heat dissipation fins 32 that protrude from the side opposite the tip end of the exposed terminal portion 20. That is, the resin portion 3 has heat dissipation fins 32 that protrude from the side opposite the mounting member (circuit board 11 in this embodiment) of the resistor 1. Therefore, heat from the resistor 1 is dissipated from one side to the mounting member and from the other side into the air by the heat dissipation fins 32, improving the heat dissipation performance of the resistor 1.

[0028] Furthermore, resin portion 3 contains base resin 301 and filler 302 having a higher thermal conductivity than base resin 301. This improves the heat dissipation of resistor 1.

[0029] The thermal conductivity of the resin portion 3 is 3 W / (m·K) or more. By making the thermal conductivity of the resin portion 3 3 W / (m·K) or more, the heat dissipation performance of the resistor 1 can be improved. By making the thermal conductivity of the resin portion 3 10 W / (m·K) or less, the cost of the resin portion 3 can be reduced and the moldability can be improved. In order to increase the thermal conductivity of the resin portion 3, it is necessary to include a large amount of filler 302. However, the more filler 302 is added, the higher the cost of the resin portion 3 becomes, and the worse the fluidity of the molten raw material that becomes the resin portion 3 becomes, which tends to make the resin portion 3 less moldable. Therefore, by making the thermal conductivity of the resin portion 3 10 W / (m·K) or less, the cost of the resin portion 3 can be reduced and the moldability can be improved.

[0030] As described above, according to this embodiment, it is possible to provide a resistor that can improve heat dissipation properties.

[0031] [Second embodiment] Fig. 5 is a perspective view of the resistor 1 according to this embodiment, and Fig. 6 is a cross-sectional view of the resistor 1 taken along a plane perpendicular to the longitudinal direction.

[0032] In this embodiment, the resistor body 2 has a pair of lead wires 24 connected to the pair of cap electrodes 22, respectively. The lead wires 24 are joined to the bottoms 221 of the cap electrodes 22 by welding or the like. The lead wires 24 are made of, for example, tin-plated conductors. The pair of lead wires 24 have exposed terminals 20 exposed outside the resin part 3 at the ends opposite the cap electrodes 22. While FIG. 5 shows the pair of lead wires 24 in a straight state, when the resistor 1 is in use, for example, the exposed terminals 20 of the pair of lead wires 24 are bent in a direction perpendicular to the longitudinal direction X and inserted into through-holes or the like of a circuit board. In this embodiment, the direction in which the tips of the exposed terminals 20 in the bent state as described above face is defined as the vertical direction Z. The vertical direction Z is a normal direction to the main surface 300 of the resin part 3. In this embodiment, the side facing the main surface 300 is referred to as the lower side, and the opposite side is referred to as the upper side. The direction perpendicular to both the longitudinal direction X and the vertical direction Z is referred to as the horizontal direction Y. The main surface 300 is the surface that faces the support member when the resistor 1 is mounted on the support member such as a circuit board.

[0033] In this embodiment, the resin body 31 is formed in a cylindrical shape that is long in the longitudinal direction X, and the plurality of heat dissipation fins 33, 34 protrude from the resin body 31 to the outer periphery.

[0034] The plurality of heat dissipating fins 33, 34 include a plurality of heat dissipating fins 33 formed in a radial pattern on the upper half of the resin portion 3, and a plurality of heat dissipating fins 34 formed below the heat dissipating fins 33 and protruding from the resin main body portion 31 on both sides in the lateral direction Y. The plurality of heat dissipating fins 33 are formed to be radial when viewed from the longitudinal direction X. The plurality of heat dissipating fins 33 are formed at equal angular intervals around a predetermined central axis. The plurality of heat dissipating fins 33 have the same protruding length. The central heat dissipating fin 33 among the plurality of heat dissipating fins 33 protrudes on the opposite side (i.e., upward) from the protruding side of the exposed terminal portion 20 in the bent state. Furthermore, a pair of heat dissipating fins 33 located at the bottom of the plurality of heat dissipating fins 33 protrude on both sides in the lateral direction Y and are formed parallel to the plurality of heat dissipating fins 34. The protruding length of the plurality of heat dissipating fins 34 increases as they are positioned lower. The lower surfaces of the pair of heat dissipation fins 34 located at the bottom form the main surface 300 .

[0035] The resistor 1 of this embodiment can be manufactured by insert molding, for example, in which the resistor body 2 is placed in a pair of molds that move back and forth in the longitudinal direction X, and molten resin is injected into the cavity and hardened.

[0036] Other configurations of this embodiment are the same as those of the first embodiment. In addition, among the symbols used in the second embodiment and the following embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as in the previous embodiments, unless otherwise specified.

[0037] (Functions and Effects of the Second Embodiment) In this embodiment, the resin portion 3 has a plurality of radially formed heat dissipation fins 33. Therefore, the resistor 1 can be made smaller without impairing heat dissipation properties. In addition, the second embodiment has the same functions and effects as the first embodiment.

[0038] In this embodiment, the protruding length of the pair of heat dissipation fins 34 located at the bottom may be made longer than the length shown in Figures 5 and 6, and bolt insertion holes for inserting bolts for attaching the resistor 1 to a mounting base may be formed in the heat dissipation fins 34. Similar modifications are possible in the following embodiments.

[0039] [Third embodiment] Fig. 7 is a perspective view of the resistor 1 in this embodiment. Fig. 8 is a front view of the resistor 1. Fig. 9 is a cross-sectional view at the center position in the longitudinal direction of the resistor 1. Fig. 10 is a cross-sectional view parallel to the longitudinal direction of the resistor 1.

[0040] In this embodiment, the configuration of the resistor 1 is improved to improve formability compared to the second embodiment.

[0041] The resistor body 2 has a pair of protruding pieces 25 protruding from each of the pair of cap electrodes 22 to one side perpendicular to the longitudinal direction X. The protruding pieces 25 extend from the end of the side portion 222 of the cap electrode 22 opposite the bottom portion 221. In this embodiment, the protruding pieces 25 are integrally formed with the cap electrode 22. The protruding ends of the protruding pieces 25 form exposed terminals 20 exposed to the outside of the resin portion 3 from the main surface 300 of the resin portion 3. The exposed terminals 20 are provided with positioning holes 251 for enabling positioning relative to a mold. This positioning will be described later. In this embodiment, as in the first embodiment, the direction in which the tips of the exposed terminals 20 face is referred to as the vertical direction Z, and the side of the vertical direction Z toward which the tips of the exposed terminals 20 face is referred to as the lower side, and the opposite side is referred to as the upper side. The direction perpendicular to the vertical direction Z and the longitudinal direction X is referred to as the horizontal direction Y.

[0042] A nest 26 is fitted into each of the pair of cap electrodes 22 of the resistor body 2. The nest 26 is made of resin and formed in a cap shape into which the cap electrodes 22 can be inserted. The nest 26 has a disk-shaped nest bottom 261 facing the bottom 221 of the cap electrode 22, and a cylindrical nest side 262 extending from the periphery of the nest bottom 261 in the longitudinal direction X and facing the side 222 of the cap electrode 22. The nest 26 also has a plate-like portion 263 at its lower end that has a thickness in the vertical direction Z.

[0043] As shown in FIG. 10 , the outer peripheral surface 262a of the insert side portion 262 is tapered so that the outer diameter increases toward the inside in the longitudinal direction. Also, as shown in FIG. 8 , the upper surface 263a of the plate-like portion 263 is inclined upward toward the inside in the longitudinal direction. Furthermore, the end surfaces 263b on both sides of the plate-like portion 263 are inclined toward the outside in the lateral direction Y toward the inside in the longitudinal direction. The outer end surface 264 of the insert 26 in the longitudinal direction and the upper surface 263a and the lower surface 263c of the plate-like portion 263 are exposed from the resin portion 3. Furthermore, the outer peripheral surface 262a of the insert side portion 262 where the heat dissipation fins 35, 36 are not formed are exposed from the resin portion 3. The other portions of the insert 26 are covered within the resin portion 3.

[0044] The resin part 3 has a cylindrical resin body 31 in which the resistor body 2 is embedded, and a plurality of heat dissipation fins 35, 36 protruding from the resin body 31. As shown in Fig. 10, the resin body 31 is formed between a pair of nests 26.

[0045] As shown in FIGS. 7 to 9 , the resin portions 3 each have a plurality of heat dissipation fins 35 that radially protrude when viewed from the longitudinal direction X, and a plurality of heat dissipation fins 36 that are formed at the lower end of the resin portion 3 and protrude to both sides in the lateral direction Y. The heat dissipation fins 35 are arranged at equal angular intervals around a predetermined central axis. As shown in FIG. 9 , in a cross section of the resistor 1 perpendicular to the longitudinal direction X, the length L of each heat dissipation fin 35, 36 is at least twice, and preferably at least 2.5 times, the maximum thickness H of each heat dissipation fin 35, 36. A pair of heat dissipation fins 35 located at the bottom of the plurality of heat dissipation fins 35 protrude to both sides in the lateral direction Y and are formed parallel to the plurality of heat dissipation fins 36. As shown in FIG. 10 , both ends of the heat dissipation fin 35 in the longitudinal direction X protrude from the resin main body 31 to both sides in the longitudinal direction X and are in close contact with the outer peripheral surface 262a of the insert side portion 262.

[0046] 9, in a cross section of the resistor 1 perpendicular to the longitudinal direction X, the heat dissipation fins 36 are formed so that the position of the protruding end portion is the same in the lateral direction Y as the position of the lowermost heat dissipation fin 35 among the plurality of heat dissipation fins 35. The lower surfaces 361 of the pair of heat dissipation fins 36 form the main surface 300 of the resin part 3. As shown in FIG. 7, both ends of the heat dissipation fin 36 in the longitudinal direction X protrude from the resin main body part 31 on both sides in the longitudinal direction X and are in close contact with the end surface 263b in the lateral direction Y of the plate-like part 263 of the insert 26.

[0047] The surface of the resin portion 3 is sloped to facilitate removal of the fixed mold 5 and the movable mold 6, which will be described later, when manufacturing the resistor 1, as shown in FIG. 10 . First, as shown in FIG. 10 , the outer circumferential surface 311 (excluding the main surface 300) of the resin body 31 is sloped so that the outer diameter increases toward the center of the resistor 1 in the longitudinal direction X. The taper angle of the outer circumferential surface 311 of the resin body 31 and the taper angle of the outer circumferential surface 262a of the insert side portion 262 are substantially the same, and the outer circumferential surface 311 of the resin body 31 and the outer circumferential surface 262a of the insert side portion 262 are flush with each other. As shown in FIGS. 7 and 8 , the heat dissipation fin 35 has a thickness that increases toward the inside in the longitudinal direction, and the end surface 351 on the protruding side and the side surfaces 352 on both sides are sloped so that the protruding length increases. The heat dissipation fins 36 have upper surfaces 362 that are inclined upward as they extend inward in the longitudinal direction. The inclination angle of the upper surfaces 362 of the heat dissipation fins 36 with respect to the longitudinal direction X and the inclination angle of the upper surfaces 263a of the plate-like portions 263 of the insert 26 with respect to the longitudinal direction X are substantially the same, and the upper surfaces 362 of the heat dissipation fins 36 and the upper surfaces 263a of the plate-like portions 263 of the insert 26 are formed flush with each other. Other configurations of the resistor 1 are the same as those in the first embodiment.

[0048] Next, a method for manufacturing the resistor 1 of this embodiment will be described. 11 is an exploded perspective view of the resistor body 2 and a pair of nests 26. The pair of nests 26 are fitted into the pair of cap electrodes 22 of the resistor body 2. Hereinafter, the resistor body 2 fitted with the pair of nests 26 will be referred to as a resistor assembly 4.

[0049] Fig. 12 is a perspective view showing the fixed mold 5, the movable mold 6, the slide core 7, and the resistance assembly 4 before mold clamping. Fig. 13 is a cross-sectional view showing the fixed mold 5, the movable mold 6, the slide core 7, and the resistance assembly 4 after mold clamping.

[0050] After the resistor assembly 4 is obtained, it is placed in a fixed-side mold 5 as shown in FIG. 12 . The fixed-side mold 5 has a fixed-side cavity surface 51 that opens in the removal direction (longitudinal direction X) of the movable-side mold 6. The fixed-side cavity surface 51 forms half of the resin portion 3 in the longitudinal direction X, and therefore has a shape corresponding to the outer shape of that portion. The fixed-side mold 5 also has a fixed-side opening 52 that communicates with the inner space of the fixed-side cavity surface 51 and opens in the removal direction (vertical direction Z) of the slide core 7. As shown in FIG. 13 , a fixed-side arrangement recess 53 is formed on the inner surface of the fixed-side opening 52, in which one of the protruding pieces 25 is arranged. A fixed-side pin 54 that is inserted into a positioning hole 251 of the protruding piece 25 is formed in the fixed-side arrangement recess 53. The fixed-side pin 54 is inserted into the positioning hole 251 of the protruding piece 25, and the resistor assembly 4 is positioned relative to the fixed-side mold 5. The surface of the resistor assembly 4 that is exposed from the resin portion 3 of the insert 26 abuts against the fixed mold 5. The resistor assembly 4 is moved in the longitudinal direction X of the resistor body 2 and placed in the fixed mold 5, and then the movable mold 6 approaches the fixed mold 5 in the longitudinal direction X to clamp the mold.

[0051] As shown in FIG. 12 , the movable-side mold 6 has a movable-side cavity surface 61 that opens toward the fixed-side cavity surface 51 of the fixed-side mold 5. The movable-side cavity surface 61 forms half of the resin portion 3 in the longitudinal direction X, and therefore has a shape corresponding to the outer shape of that portion. The movable-side mold 6 also has a movable-side opening 62 that communicates with the inner space of the movable-side cavity surface 61 and opens in the removal direction of the slide core 7. As shown in FIG. 13 , the inner surface of the movable-side opening 62 has a movable-side arrangement recess 63 in which a protruding piece 25 different from the protruding piece 25 positioned in the fixed-side mold 5 is arranged. The movable-side arrangement recess 63 has a movable-side pin 64 that is inserted into a positioning hole 251 of the protruding piece 25. The resistor assembly 4 is positioned relative to the movable-side mold 6 by inserting the movable-side pin 64 into the positioning hole 251 of the protruding piece 25. In addition, the surface of the resistor assembly 4 that is exposed from the resin portion 3 of the insert 26 abuts against the movable mold 6.

[0052] After the movable-side mold 6 is clamped to the fixed-side mold 5, the slide core 7 is inserted into the fixed-side opening 52 and the inside of the fixed-side opening 52. The side surface of the slide core 7, the inner surface of the fixed-side opening 52, and the inner surface of the movable-side opening 62 are formed with draft angles to make it easier to remove the slide core 7 from the fixed-side opening 52 and the movable-side opening 62. After the slide core 7 is clamped to the fixed-side mold 5 and the movable-side mold 6, molten resin is injected into the region surrounded by the fixed-side cavity surface 51, the movable-side cavity surface 61, and the slide core 7 and hardened, thereby insert-molding the resin portion 3. After the resin portion 3 is molded, the slide core 7 is removed from the fixed-side opening 52 and the movable-side opening 62, and the movable-side mold 6 is separated from the fixed-side mold 5 in the longitudinal direction X, thereby enabling the resistor 1 to be removed from the fixed-side mold 5.

[0053] (Functions and Effects of the Third Embodiment) In a cross section of the resistor 1 perpendicular to the longitudinal direction X, the length L of the heat dissipation fins 35, 36 is at least twice the maximum thickness T of the heat dissipation fins 35, 36. This makes it easy to increase the overall surface area of ​​the resistor 1 and improve the heat dissipation performance of the resistor 1. Furthermore, by configuring the heat dissipation fins 35, 36 as part of the resin portion 3, the heat dissipation fins 35, 36 with the long protruding lengths described above can be easily formed by molding. Furthermore, in this embodiment, the surface of the resin portion 3 is sloped to facilitate removal of the fixed mold 5 and the movable mold 6. This makes it easier to mold the resin portion 3. In addition, the same functions and effects as those of the first and second embodiments are provided.

[0054] [Fourth embodiment] Fig. 14 is a perspective view of the resistor 1 in this embodiment. Fig. 15 is a cross-sectional view perpendicular to the longitudinal direction X of the resistor 1 in this embodiment.

[0055] 14, in this embodiment, the outer longitudinal ends of each of the pair of cap electrodes 22 constitute a cap exposed portion 223 exposed from the resin portion 3. The cap exposed portion 223 is constituted by the bottom portion 221 and the outer longitudinal portions of the side portions 222.

[0056] The resistor body 2 has a pair of terminal pieces 27 respectively joined to the bottoms 221 of the pair of cap electrodes 22. Each terminal piece 27 protrudes from the cap electrode 22 in a direction perpendicular to the longitudinal direction X. The terminal pieces 27 constitute exposed terminal portions 20 whose entirety is exposed from the resin portion 3. In this embodiment, as in the first embodiment, the direction in which the tip of the exposed terminal portion 20 faces is referred to as the vertical direction Z, and one side of the vertical direction Z to which the tip of the exposed terminal portion 20 faces is referred to as the lower side, and the opposite side is referred to as the upper side. The direction perpendicular to the vertical direction Z and the longitudinal direction X is referred to as the horizontal direction Y.

[0057] The resin part 3 has a resin body part 31 in which the resistor body part 2 is embedded, and horizontal fins 37 and vertical fins 381, 382 protruding from the resin body part 31. The horizontal fins 37 are heat dissipation fins protruding from the resin body part 31 on both sides in the horizontal direction Y. The vertical fins 381, 382 are heat dissipation fins protruding from the resin body part 31 in the vertical direction Z. In this embodiment, the resin part 3 has two horizontal fins 37 on each side in the horizontal direction Y. The resin part 3 also has six vertical fins 381, 382 protruding upward.

[0058] The four horizontal fins 37 are formed at the lower end of the resin part 3. The four horizontal fins 37 have the same protruding length. As shown in FIG. 15 , the two upper horizontal fins 37 of the four horizontal fins 37 have inclined side surfaces 371 on both sides so that the thickness decreases toward the protruding end. The two lower horizontal fins 37 of the four horizontal fins 37 have inclined upper side surfaces 371 that slope downward toward the protruding end. These inclinations are intended to facilitate the removal of the slide core 7, which will be described later, during the manufacture of the resistor 1. The lower surfaces of the two lower horizontal fins 37 of the four horizontal fins 37 are flat surfaces perpendicular to the longitudinal direction Z and form the main surface 300 of the resin part 3.

[0059] The upper ends of the six vertical fins 381, 382 are at the same height in the vertical direction Z. The six vertical fins 381, 382 include four first vertical fins 381 formed straight upward from the resin main body 31, and two second vertical fins 382 each having a base end 382a along the horizontal direction Y and a tip end 382b protruding upward from the base end 382a. The two second vertical fins 382 are formed on both sides of the four first vertical fins 381 in the horizontal direction Y. The second vertical fins 382 are formed at positions overlapping with the horizontal fins 37 in the vertical direction Z. In other words, the formation regions of the second vertical fins 382 and the formation regions of the horizontal fins 37 overlap when viewed from the vertical direction Z. In this embodiment, the length in the horizontal direction Y of the base end 382a of the second vertical fin 382 is shorter than the length in the horizontal direction Y of the horizontal fin 37. The six vertical fins 381, 382 are formed so as to fit within a range in the horizontal direction Y from the protruding end of the horizontal fin 37 on one side to the protruding end of the horizontal fin 37 on the other side.

[0060] 15, the four first vertical fins 381 have inclined side surfaces 381a on both sides so that the thickness decreases toward the top. The tip portions 382b of the two second vertical fins 382 have inclined side surfaces 382c on both sides so that the thickness decreases toward the top. These inclinations are intended to facilitate the release of a movable mold 6, which will be described later, when manufacturing the resistor 1, as will be described later.

[0061] In a cross section of the resistor 1 perpendicular to the longitudinal direction X, the length of the heat dissipation fins (i.e., the horizontal fins 37 and the vertical fins 381, 382) is at least twice, and preferably at least 2.5 times, the maximum thickness T. In the case where the heat dissipation fin has a curved shape like the second vertical fin 382, ​​the length of the second vertical fin 382 means the total length of the length L1 of the base end portion 382a and the length L2 of the tip end portion 382b.

[0062] Next, a method for manufacturing the resistor 1 of this embodiment will be described. FIG. 16 is a cross-sectional view showing how the resistor body 2 is assembled to the fixed mold 5. As shown in FIG. 16, the resistor body 2 is first placed in the fixed mold 5. The fixed mold 5 has a fixed cavity surface 51 that opens to one side. The resistor body 2 is moved in the vertical direction Z relative to the fixed mold 5 and placed at a predetermined position in the fixed mold 5. By placing the resistor body 2 in the fixed mold 5 in a direction perpendicular to the longitudinal direction X, the assembly of the resistor body 2 to the fixed mold 5 is facilitated compared to a configuration in which the resistor body 2 is placed in the longitudinal direction X relative to the fixed mold 5. When the resistor body 2 is placed in the fixed mold 5, the cap exposed portion 223 and the terminal piece 27 are held in the holding recess 55 of the fixed mold 5.

[0063] A slide core 7 that is movable in the horizontal direction Y is disposed within the fixed mold 5. The slide core 7 is used to form the horizontal fins 37 of the resin part 3 together with the fixed mold 5. The pair of slide cores 7 are fixed to the fixed mold 5 at predetermined positions in the horizontal direction Y according to the length of the horizontal fins 37. Then, the movable mold 6 moves in the vertical direction Z relative to the fixed mold 5, and the mold is clamped.

[0064] FIG. 17 is a cross-sectional view showing the movable mold 6 being brought closer to the fixed mold 5 on which the resistor body 2 is mounted. FIG. 18 is a cross-sectional view showing the clamped fixed mold 5, movable mold 6, and resistor body 2. The movable mold 6 has a movable cavity surface 61 that opens toward the fixed cavity surface 51. The movable cavity surface 61 is used to form six vertical fins 381, 382. Of the six vertical fins 381, 382, ​​the second vertical fin 382 is formed in a space defined by the fixed cavity surface 51, the movable cavity surface 61, and the slide core 7. The movable mold 6 also has a holding portion 65 that protrudes toward the fixed mold 5 and is used to hold the cap exposed portion 223 of the resistor body 2 together with the holding recess 55.

[0065] Molten resin is injected into the area surrounded by the clamped fixed-side cavity surface 51, the movable-side cavity surface 61, and the pair of slide cores 7, and then hardened, thereby insert-molding the resin part 3. After the resin part 3 is molded, the pair of slide cores 7 are moved in the horizontal direction Y so as to move away from each other, and the movable-side mold 6 moves away from the fixed-side mold 5 in the vertical direction Z, thereby enabling the resistor 1 to be removed from the fixed-side mold 5.

[0066] (Functions and Effects of the Fourth Embodiment) In this embodiment, the resin part 3 has, as heat dissipation fins, only horizontal fins 37 and vertical fins 381, 382. Therefore, the structure of the mold for molding the resin part 3 can be simplified.

[0067] The resin part 3 also includes a plurality of horizontal fins 37 protruding on both sides in the horizontal direction Y, and a plurality of vertical fins 381, 382 protruding only upward in the vertical direction Z. The plurality of vertical fins 381, 382 include a first vertical fin 381 formed straight in the vertical direction Z, and a second vertical fin 382 having a base end 382a along the horizontal direction Y and a tip end 382b protruding from the base end 382a to one side in the vertical direction Z. The second vertical fin 382 is formed at a position overlapping the horizontal fin 37 in the vertical direction Z. As a result, the second vertical fin 382 is formed in the space between the first vertical fin 381 and the horizontal fin 37, i.e., in the dead space, so that the surface area of ​​the resin part 3 can be increased while preventing the resistor 1 from becoming large. In addition, the second embodiment has the same functions and effects as the first embodiment.

[0068] [Fifth embodiment] FIG. 19 is a perspective view of the resistor 1 in this embodiment.

[0069] This embodiment has the same basic configuration as the fourth embodiment, but the shape of the terminal piece 27 and the area where the resin portion 3 is formed are changed.

[0070] The terminal piece 27 has a first portion 271 overlapping and joined to the bottom portion 221 of the cap electrode 22, a second portion 272 extending outward in the longitudinal direction from an end portion of the first portion 271 opposite to the protruding sides of the vertical fins 381, 382, ​​and a third portion 273 extending from an outer end portion of the second portion 272 in the longitudinal direction to the opposite side to the protruding sides of the vertical fins 381, 382. The terminal piece 27 configures an exposed terminal portion 20 in which the outer longitudinal portion of the second portion 272 and the third portion 273 are exposed from the resin portion 3. The resin portion 3 is formed to extend outward in the longitudinal direction beyond the pair of cap electrodes 22. Other configurations of the resistor 1 are the same as those in the fourth embodiment.

[0071] The resistor 1 of this embodiment can be manufactured by the same method as that of the fourth embodiment. In this embodiment, when the resistor body 2 is held by the fixed mold 5, only the exposed terminal portion 20 is held by the fixed mold 5.

[0072] (Functions and Effects of the Fifth Embodiment) In this embodiment, the same functions and effects as those of the fifth embodiment are achieved, and the resin portion 3 is formed over a wider area, so that the heat dissipation of the resistor 1 can be further improved.

[0073] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0074] [1] A resistor (1) comprising a resistor body (2) and a resin part (3) covering the resistor body (2), the resin part (3) having heat dissipation fins (32, 33, 34, 35, 36, 37, 381, 382).

[0075] [2] The resistor (1) according to [1], wherein the heat dissipation fins (32, 33, 34, 35, 36, 37, 381, 382) are formed elongated in the longitudinal direction (X) of the resistor body (2).

[0076] [3] The resistor (1) according to [1] or [2], wherein in a cross section perpendicular to the longitudinal direction (X) of the resistor body (2), the length (L) of the heat dissipation fins (35, 36, 37, 381, 382) is at least twice the maximum thickness (T) of the heat dissipation fins (35, 36, 37, 381, 382).

[0077] [4] The resistor (1) according to any one of [1] to [3], wherein the resin part (3) has, as the heat dissipation fins (37, 381, 382), horizontal fins (37) protruding in a horizontal direction (Y) perpendicular to the longitudinal direction (X) of the resistor main body part (2), and vertical fins (381, 382) protruding in a vertical direction (Z) perpendicular to both the longitudinal direction (X) and the horizontal direction (Y).

[0078] [5] The resistor (1) described in [4], wherein the resin part (3) comprises a plurality of horizontal fins (37) protruding on both sides in the horizontal direction (Y) and a plurality of vertical fins (381, 382) protruding only on one side in the vertical direction (Z), and the plurality of vertical fins (381, 382) comprise a first vertical fin (381) formed straight in the vertical direction (Z), and a second vertical fin (382) having a base end (382a) along the horizontal direction (Y) and a tip end (382b) protruding from the base end (382a) to the one side in the vertical direction (Z), and the second vertical fin (382) is formed at a position overlapping with the horizontal fins (37) in the vertical direction (Z).

[0079] [6] A resistor (1) according to any one of [1] to [3], wherein when viewed from the longitudinal direction (X) of the resistor body (2), the resin part (3) has a plurality of the heat dissipation fins (33, 35) that protrude radially.

[0080] [7] A resistor (1) according to any one of [1] to [6], wherein the resistor body (2) has an exposed terminal portion (20) exposed from the resin portion (3), and the resin portion (3) has the heat dissipation fins (32, 33, 35, 381, 382) protruding on the side opposite to the tip side of the exposed terminal portion (20).

[0081] [8] The resistor (1) according to any one of [1] to [7], wherein the resin portion (3) contains a base resin (301) and a filler (302) having a higher thermal conductivity than the base resin (301).

[0082] [9] The resistor (1) according to [8], wherein the thermal conductivity of the resin portion (3) is 3 W / (m·K) or more and 10 W / (m·K) or less.

[0083] (Addendum) Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above-described embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented within the scope of its spirit. [Explanation of symbols]

[0084] 1...Resistor 2...Resistor body 20...Exposed terminal section 3...Resin part 301...Base resin 302...Filler 32~37...Heat dissipation fins 381...First vertical fin 382...Second vertical fin 382a...Proximal end 382b…Tip T: Maximum thickness X: Longitudinal direction Y: Horizontal Z: Vertical direction

Claims

1. A resistor main body; a resin portion covering the resistor body, the resin portion has a heat dissipation fin, the resin portion has, as the heat dissipation fins, only a plurality of horizontal fins protruding on both sides in a horizontal direction perpendicular to the longitudinal direction of the resistor body, and a plurality of vertical fins protruding only on one side in a vertical direction perpendicular to both the longitudinal direction and the horizontal direction; the plurality of vertical fins include a first vertical fin formed straight in the vertical direction, and a second vertical fin having a base end portion along the horizontal direction and a tip end portion protruding from the base end portion to the one side in the vertical direction, The second vertical fin is formed at a position overlapping with the horizontal fin in the vertical direction. resistor.

2. The heat dissipation fins are formed long in the longitudinal direction of the resistor body.

2. The resistor of claim 1.

3. In a cross section perpendicular to the longitudinal direction of the resistor body, the length of the heat dissipation fin is at least twice the maximum thickness of the heat dissipation fin.

3. The resistor according to claim 1 or 2.

4. the resistor body has an exposed terminal portion exposed from the resin portion, The resin portion has the heat dissipation fins protruding on the side opposite to the tip end side of the exposed terminal portion.

4. A resistor according to claim 1.

5. The resin portion contains a base resin and a filler having a thermal conductivity higher than that of the base resin.

5. A resistor according to claim 1.

6. The thermal conductivity of the resin portion is 3 W / (m·K) or more and 10 W / (m·K) or less.

6. The resistor of claim 5.

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