Noise filter

Abstract

[Problem] To provide a noise filter which has higher heat dissipation performance than conventional products and can suppress temperature rise even when each part including a conductor is miniaturized. [Solution] This noise filter is provided with a magnetic core, a conductor, a mold part, and a heat conduction part. The mold part is composed of a first thermally conductive material. The heat conduction part is composed of a second heat conductive material having a thermal conductivity higher than that of the first heat conductive material. When the noise filter is used, the heat conduction part is disposed so as to be in contact with an external member to which heat is to be dissipated. In the mold part, an opening penetrating the mold part and reaching the outer peripheral surface of the magnetic core is formed. The heat conduction part has an insertion portion that extends into the opening part, and is configured to be in contact with the magnetic core at the insertion portion.

Description

Noise Filter

[0001] The present disclosure relates to noise filters.

[0002] Noise filters have been proposed, such as that disclosed in Patent Document 1. The noise filter described in Patent Document 1 includes a magnetic core and a conductor (a conductive bar as referred to in Patent Document 1), and has a structure in which the magnetic core and the conductor are partially molded with a resin material.

[0003] Japanese Patent Application Laid-Open No. 2020-5043

[0004] The above-described noise filter constitutes part of the power supply path to the motor that serves as the power source in, for example, electric vehicles or hybrid vehicles. In such applications, a large current flows through the conductor, causing the conductor to generate a considerable amount of heat. If the magnetic core becomes excessively hot due to the heat generated by the conductor, this may adversely affect the performance of the noise filter. Furthermore, if the noise filter becomes excessively hot, this may adversely affect the performance of electronic components or other devices located near the noise filter. Therefore, it is important to appropriately suppress the heat generated by the noise filter.

[0005] One way to suppress heat generation in conductors is to use thicker conductors. However, this would require larger noise filters, making it difficult to install them in small spaces. Furthermore, larger noise filters would also increase the weight of the equipment in which they are installed. While adding an air-cooling or water-cooling mechanism to combat heat generation would require additional space, making it difficult to install them in small spaces and resulting in increased weight.

[0006] In one aspect of the present disclosure, it is desirable to provide a noise filter that has higher heat dissipation performance than conventional products and is capable of suppressing temperature rise even when each part including a conductor is miniaturized.

[0007] (1) One aspect of the present disclosure is a noise filter comprising a magnetic core, a conductor, a molded portion, and a heat-conducting portion. The magnetic core is a magnetic material configured in an annular or cylindrical shape. The conductor is disposed so as to penetrate the inner periphery of the magnetic core. The molded portion is made of a first thermally conductive material and molds a portion of the magnetic core and a portion of the conductor. The heat-conducting portion is made of a second thermally conductive material having a higher thermal conductivity than the first thermally conductive material and is disposed so as to contact a portion of the magnetic core and a portion of the molded portion. When the noise filter is in use, the heat-conducting portion is disposed so as to contact an external member to which heat is dissipated, thereby conducting heat from the magnetic core and the molded portion to the external member. The molded portion has an opening that penetrates the molded portion and reaches the outer periphery of the magnetic core. The heat-conducting portion has an inlet that enters the opening and is configured to contact the magnetic core at the inlet.

[0008] In the noise filter configured as described above, the molded portion is made of the first thermally conductive material, and the heat conducting portion is made of the second thermally conductive material, so that when the temperatures of the magnetic core and the conductor rise, the heat from the magnetic core and the conductor can be released to the molded portion and the heat conducting portion, thereby preventing the magnetic core and the conductor from rising excessively in temperature.

[0009] In particular, the insertion portion of the heat conduction portion enters the opening formed in the molded portion and contacts the magnetic core, so that the heat of the magnetic core can be directly transferred to the heat conduction portion, improving the efficiency of heat transfer to the external component to which the heat is dissipated compared to a location where the molded portion is interposed between the magnetic core and the heat conduction portion.

[0010] Therefore, since the noise filter's heat dissipation performance is improved, the conductors can be allowed to generate more heat than in conventional products, making it possible to use thinner conductors that are more likely to generate heat than in conventional products, thereby enabling the noise filter to be made more compact.

[0011] The noise filter of the present disclosure can further optionally employ the following configurations.

[0012] (2) In one aspect of the present disclosure, the heat conduction portion may be configured to contact an inner circumferential surface of the opening.

[0013] (3) In one aspect of the present disclosure, the heat conduction portion may be configured to form a gap between itself and an inner circumferential surface of the opening.

[0014] (4) In one aspect of the present disclosure, the first thermally conductive material may have a thermal conductivity of 1 W / m K or more and less than 1.4 W / m K. The second thermally conductive material may have a thermal conductivity of 1.4 W / m K or more and 5 W / m K or less.

[0015] (5) In one aspect of the present disclosure, the heat conduction portion may be configured such that, when the noise filter is in use and sandwiched between the magnetic core and the external member and / or between the molded portion and the external member and subjected to a compressive load, the heat conduction portion deforms and comes into close contact with the external member.

[0016] FIG. 1A is a perspective view of the noise filter of the first embodiment. FIG. 1B is a cross-sectional view of the noise filter of the first embodiment taken along the line IB-IB in FIG. 2C. FIG. 1C is a cross-sectional view of the noise filter of the first embodiment taken along the line IC-IC in FIG. 2B. FIG. 2A is a plan view of the noise filter of the first embodiment. FIG. 2B is a front view of the noise filter of the first embodiment. FIG. 2C is a right side view of the noise filter of the first embodiment. FIG. 2D is a bottom view of the noise filter of the first embodiment. FIG. 3A is a cross-sectional view of the noise filter of the first embodiment taken along the line IB-IB in FIG. 2C, with the heat conduction section further exploded. FIG. 3B is a cross-sectional view of the noise filter of the first embodiment taken along the line IC-IC in FIG. 2B, with the heat conduction section further exploded. FIG. 3C is a perspective view for explaining the use state of the noise filter of the first embodiment. FIG. 4A is a cross-sectional view of the noise filter of the second embodiment taken along the line IB-IBB in FIG. 2C. FIG. 4B is a cross-sectional view of the noise filter of the second embodiment taken along the line IC-IC in FIG. 2B. FIG. 4C is an enlarged view of the IVC portion shown in FIG. 4A. FIG. 4D is an enlarged view of the IVD portion shown in FIG. 4A. FIG. 4E is an enlarged view of the IVE portion shown in FIG. 4B. FIG. 4F is an enlarged view of the IVF portion shown in FIG. 4B. FIG. 5A is a perspective view of the noise filter of the third embodiment. FIG. 5B is a cross-sectional view of the noise filter of the third embodiment taken along the line VB-VB in FIG. 6C. FIG. 5C is a cross-sectional view of the noise filter of the third embodiment taken along the line VC-VC in FIG. 6B. FIG. 6A is a plan view of the noise filter of the third embodiment. FIG. 6B is a front view of the noise filter of the third embodiment. FIG. 6C is a right side view of the noise filter of the third embodiment. FIG. 6D is a bottom view of the noise filter of the third embodiment.

[0017] 1, 21, 31...noise filter, 3...magnetic core, 3A...outer surface, 5...conductor, 5A, 5B...through hole, 7...molded portion, 7A...opening, 9...thermal conduction portion, 9A...first surface, 9B...second surface, 11A, 11B...fixing portion, 13A, 13B...collar, 15...insertion portion, 17...external member, 23...gap, 33A, 33B...heat dissipation fin.

[0018] Next, the above-mentioned noise filter will be described with reference to exemplary embodiments.

[0019] (1) First Embodiment [Configuration of Noise Filter] As shown in Figures 1A, 1B, 1C, 2A, 2B, 2C, and 2D, a noise filter 1 according to the first embodiment includes a magnetic core 3, a conductor 5, a molded portion 7, and a heat-conducting portion 9. The left side view of the noise filter 1 is identical to the right side view (see Figure 2C). The back view of the noise filter 1 is identical to the front view (see Figure 2B).

[0020] 1B and 1C, the magnetic core 3 is a magnetic material configured in a ring-shaped or cylindrical shape. As shown in FIGS. 1B and 1C, the conductor 5 is arranged so as to penetrate the inner periphery of the magnetic core 3. In this embodiment, the conductor 5 is configured as a long, thin plate extending in the front-to-rear direction in the drawings, with its thickness oriented in the up-to-down direction in the drawings. Near both ends of the conductor 5 in the longitudinal direction (front-to-rear direction in the drawings), through holes 5A and 5B are formed that penetrate the conductor 5 in the thickness direction.

[0021] The molded portion 7 is made of a first thermally conductive material. In this embodiment, the first thermally conductive material has a thermal conductivity of 1 W / m·K or more and less than 1.4 W / m·K, and a volume resistivity of 1.0×10 １３ The thermally conductive resin (trade name: Xecot (registered trademark), manufactured by Unitika Ltd.) with a thermal conductivity of more than Ω m is used. The molded portion 7 molds a part of the magnetic core 3 and a part of the conductor 5. The molded portion 7 fills the space between the inner periphery of the magnetic core 3 and the outer periphery of the conductor 5.

[0022] The molded portion 7 has fixing portions 11A and 11B that protrude in the left-right direction in the drawing. Metal collars 13A and 13B are provided on the fixing portions 11A and 11B. When the noise filter 1 is fixed to an installation location with a bolt (not shown), the bolt shaft is passed through the collars 13A and 13B.

[0023] The heat conducting portion 9 is made of a second heat conducting material having a higher thermal conductivity than the first heat conducting material. In this embodiment, the second heat conducting material has a thermal conductivity of 1.4 W / m K or more and 5 W / m K or less, and a volume resistivity of 1.0×10 １１ A thermally conductive resin (trade name: CPLK, manufactured by Kitagawa Industries Co., Ltd.) having a hardness (ASKER C) of preferably 5 to 50 (more preferably 30 to 50) is used.

[0024] The heat conductive portion 9 is disposed so as to contact a portion of the magnetic core 3 and a portion of the molded portion 7. More specifically, as shown in FIGS. 3A and 3B , an opening 7A is formed in the molded portion 7. The opening 7A penetrates the molded portion 7 and reaches the outer peripheral surface 3A of the magnetic core 3. The heat conductive portion 9 has an inlet portion 15 that protrudes upward in the figures. The heat conductive portion 9 is configured so that a first surface 9A at the tip of the inlet portion 15 in the protruding direction contacts the magnetic core 3, and a second surface 9B around the inlet portion 15 contacts the molded portion 7. In addition, in this embodiment, the inlet portion 15 is configured so as to also contact the inner peripheral surface of the opening 7A.

[0025] 3C , when the noise filter 1 is in use, the heat conductive portion 9 is arranged so as to be in contact with an external member 17 (e.g., a water-cooled cooling plate) to which heat is to be dissipated, and conducts heat from the magnetic core 3 and the molded portion 7 to the external member 17. When the heat conductive portion 9 is sandwiched between the magnetic core 3 and the external member 17 and / or between the molded portion 7 and the external member 17 and receives a compressive load, the heat conductive portion 9 deforms and comes into close contact with the external member 17. This can promote heat transfer from the heat conductive portion 9 to the external member 17 compared to when the heat conductive portion 9 does not deform easily.

[0026] In this embodiment, the thermal conductivities of the first and second thermally conductive materials were measured using a commercially available hot disk method thermal property measuring device (TPS-500, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) in accordance with a measurement method conforming to ISO 22007-2. The volume resistivities of the first and second thermally conductive materials were measured using a commercially available high-precision resistivity meter (MCP-HT450, manufactured by Mitsubishi Chemical Corporation) in accordance with a measurement method conforming to JIS K 6911.

[0027] [Effect] In the noise filter 1 configured as described above, the molded portion 7 is made of the first thermally conductive material, and the heat-conducting portion 9 is made of the second thermally conductive material. Therefore, when the temperatures of the magnetic core 3 and the conductor 5 rise, the heat of the magnetic core 3 and the conductor 5 can be released to the molded portion 7 and the heat-conducting portion 9, thereby preventing the temperatures of the magnetic core 3 and the conductor 5 from rising excessively.

[0028] In particular, the inlet portion 15 of the heat conductive portion 9 enters the opening 7A formed in the molded portion 7 and contacts the magnetic core 3. Therefore, the heat of the magnetic core 3 can be directly transferred to the heat conductive portion 9, and the efficiency of heat transfer to the external member 17, which is the heat dissipation destination, can be improved compared to a location where the molded portion 7 is interposed between the magnetic core 3 and the heat conductive portion 9.

[0029] In this embodiment, the insertion portion 15 is in contact with the inner peripheral surface of the opening 7A, so that heat transfer occurs from the molded portion 7 to the heat conduction portion 9 at the inner peripheral surface of the opening 7A, thereby facilitating heat dissipation from the molded portion 7.

[0030] Therefore, the noise filter 1's heat dissipation performance is improved, and the temperature rise of the noise filter 1 can be suppressed more than in conventional products. Alternatively, if the noise filter 1's temperature rise can be tolerated to the same extent as in conventional products, the conductor 5 can be allowed to heat up more than in conventional products. In this case, for example, it is possible to use a conductor 5 that is thinner and more likely to generate heat than in conventional products, thereby making it possible to reduce the noise filter 1's size.

[0031] (2) Second Embodiment Next, a second embodiment will be described. Note that the second embodiment and subsequent embodiments are embodiments in which a part of the configuration exemplified in the first embodiment is modified. Therefore, differences from the first embodiment will be mainly described in detail. Configurations equivalent to those in the first embodiment will be assigned the same reference numerals as in the first embodiment, and detailed description thereof will be omitted.

[0032] 4A and 4B, the noise filter 21 of the second embodiment differs from the noise filter 1 of the first embodiment in the structure shown in a cross-sectional view of the noise filter 21. More specifically, the noise filter 21 of the second embodiment differs from the noise filter 1 of the first embodiment in that it has a gap 23 between the molded portion 7 and the heat conductive portion 9, as shown in FIGS.

[0033] In the first embodiment, the gap 23 is formed between the inner periphery of the opening 7A and the outer periphery of the insertion portion 15 shown in Figures 3A and 3B. In the second embodiment, the shapes and dimensions of the magnetic core 3, the conductor 5, and the molded portion 7 are configured to be exactly the same as in the first embodiment. In the second embodiment, the shape and dimensions of the heat conductive portion 9 are configured so that the front-to-back dimensions and left-to-right dimensions in the figures are smaller than those of the insertion portion 15 of the first embodiment shown in Figures 3A and 3B, thereby forming the gap 23.

[0034] The gap 23 is located in a position that cannot be seen when looking at the exterior of the noise filter 21 of the second embodiment. Therefore, the six-sided view of the noise filter 21 of the second embodiment is exactly the same as the six-sided view of the noise filter 1 of the first embodiment.

[0035] [Effects] The noise filter 21 configured as described above also achieves the same effects and functions as the noise filter 1 described in the first embodiment. Therefore, the noise filter 21 has improved heat dissipation performance, which makes it possible to suppress temperature rise in the noise filter 21 more effectively than conventional products. Alternatively, if the noise filter 21 can tolerate a temperature rise to the same extent as conventional products, the conductor 5 can be allowed to generate more heat than conventional products. In this case, for example, it is possible to use a conductor 5 that is thinner and more likely to generate heat than conventional products, thereby enabling the noise filter 21 to be made more compact.

[0036] Furthermore, in the case of the second embodiment, the noise filter 21 has the gap 23 as described above between the molded portion 7 and the heat conductive portion 9. Therefore, in the second embodiment, it is easier to fit the insertion portion 15 into the inner periphery of the opening 7A than in the first embodiment, and the productivity of the noise filter 21 can be improved.

[0037] (3) Third Embodiment Next, a third embodiment will be described.

[0038] 5A, 5B, 5C, 6A, 6B, 6C, and 6D, the noise filter 31 of the third embodiment differs from the noise filter 1 of the first embodiment in that it has heat dissipation fins 33A and 33B. The heat dissipation fins 33A and 33B are molded integrally with the molded portion 7 using the first thermally conductive material that constitutes the molded portion 7.

[0039] [Effects] The noise filter 31 configured as described above also achieves the same effects and functions as the noise filter 1 described in the first embodiment. Therefore, the noise filter 31 has improved heat dissipation performance, which makes it possible to suppress temperature rise in the noise filter 31 more effectively than conventional products. Alternatively, if the noise filter 31 can tolerate a temperature rise to the same extent as conventional products, the conductor 5 can be allowed to generate more heat than conventional products. In this case, for example, it is possible to use a conductor 5 that is thinner and more likely to generate heat than conventional products, thereby enabling the noise filter 31 to be made smaller.

[0040] In the third embodiment, the noise filter 31 has the heat dissipation fins 33A and 33B as described above. This promotes heat dissipation from the heat dissipation fins 33A and 33B, improving the heat dissipation performance of the noise filter 21 compared to a case where no similar heat dissipation fins are provided.

[0041] (4) Other Embodiments While the noise filter has been described above using exemplary embodiments, the above-described embodiments are merely examples of one aspect of the present disclosure. In other words, the present disclosure is not limited to the above-described exemplary embodiments, and can be embodied in various forms without departing from the technical spirit of the present disclosure.

[0042] For example, in the above embodiment, a first thermally conductive material and a second thermally conductive material in which components are blended in a specific composition ratio are exemplified, but the specific components and composition ratios of the first thermally conductive material and the second thermally conductive material are not limited to the above example.

[0043] Furthermore, for example, in the above third embodiment, an example was shown in which heat dissipation fins 33A, 33B were added to both the front and rear sides of the molded portion 7, but similar heat dissipation fins may also be added to the upper surface side or both the left and right sides of the molded portion 7.

[0044] Note that multiple functions realized by one component exemplified in the above embodiments may be realized by multiple components. One function realized by one component exemplified in the above embodiments may be realized by multiple components. Multiple functions realized by multiple components exemplified in the above embodiments may be realized by one component. One function realized by multiple components exemplified in the above embodiments may be realized by one component. Part of the configuration exemplified in the above embodiments may be omitted. At least part of the configuration exemplified in one of the above embodiments may be added to or replaced with a configuration exemplified in an embodiment other than that one embodiment.

[0045] (5) Technical Ideas Disclosed in the Specification [Item 1] A noise filter comprising: a magnetic core that is a magnetic body configured in an annular or cylindrical shape; a conductor arranged to penetrate the inner periphery of the magnetic core; a molded portion made of a first thermally conductive material and molding a part of the magnetic core and a part of the conductor; and a heat conduction portion made of a second thermally conductive material having a higher thermal conductivity than the first thermally conductive material and arranged to be in contact with a part of the magnetic core and a part of the molded portion, and arranged to be in contact with an external member to which heat is dissipated when the noise filter is in use, and to conduct heat from the magnetic core and the molded portion to the external member, wherein an opening is formed in the molded portion that penetrates through the molded portion and reaches the outer periphery of the magnetic core, and the heat conduction portion has an inlet portion that enters the opening and is configured to be in contact with the magnetic core at the inlet portion.

[0046] [Item 2] The noise filter according to item 1, wherein the heat conduction portion is configured to be in contact with an inner circumferential surface of the opening portion.

[0047] [Item 3] The noise filter according to item 1, wherein the heat conduction portion is configured to form a gap between itself and an inner circumferential surface of the opening.

[0048] [Item 4] The noise filter according to any one of items 1 to 3, wherein the first thermally conductive material has a thermal conductivity of 1 W / m·K or more and less than 1.4 W / m·K, and the second thermally conductive material has a thermal conductivity of 1.4 W / m·K or more and 5 W / m·K or less.

[0049] [Item 5] The noise filter according to any one of items 1 to 4, wherein the heat conduction portion is configured such that, when the heat conduction portion is sandwiched between the magnetic core and the external member and / or between the molded portion and the external member and receives a compressive load during use of the noise filter, the heat conduction portion deforms and comes into close contact with the external member.

Claims

1. A noise filter comprising: a magnetic core which is a magnetic body formed in a ring or cylindrical shape; a conductor arranged to penetrate the inner periphery of the magnetic core; a molded section made of a first thermally conductive material and molding a part of the magnetic core and a part of the conductor; and a heat conduction section made of a second thermally conductive material having a higher thermal conductivity than the first thermally conductive material and arranged to be in contact with a part of the magnetic core and a part of the molded section, and arranged to be in contact with an external member to which heat is dissipated when the noise filter is in use, and configured to conduct heat from the magnetic core and the molded section to the external member; wherein the molded section has an opening which penetrates through the molded section and reaches the outer periphery of the magnetic core, and the heat conduction section has an entry section which enters the opening and is configured to be in contact with the magnetic core at the entry section.

2. A noise filter according to claim 1, wherein the heat conductive portion is configured to be in contact with an inner peripheral surface of the opening portion.

3. A noise filter according to claim 1, wherein the heat conductive portion is configured to form a gap between the heat conductive portion and an inner peripheral surface of the opening.

4. A noise filter according to any one of claims 1 to 3, wherein the first thermally conductive material has a thermal conductivity of 1 W / m.K or more and less than 1.4 W / m.K, and the second thermally conductive material has a thermal conductivity of 1.4 W / m.K or more and 5 W / m.K or less.

5. A noise filter as claimed in any one of claims 1 to 3, wherein the heat conductive portion is configured such that, when the heat conductive portion is sandwiched between the magnetic core and the external member and / or between the molded portion and the external member and receives a compressive load during use of the noise filter, the heat conductive portion deforms and comes into close contact with the external member.

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