Noise filter

Abstract

A noise filter (1) comprises a first core (3) and a second core (4), both made of ferrite. The second core (4) faces the first core (3). The noise filter (1) includes a bus bar (2), a case (10), and an elastic means (12). The bus bar (2) penetrates between the first core (3) and the second core (4), and has a connection terminal at each end. The case (10) accommodates the first core (3) and the second core (4), and allows the bus bar (2) to penetrate therethrough. The elastic means (12) is provided in the case (10) and can bias the first core (3) toward the second core (4).

Description

Noise Filter

[0001] The present disclosure relates to a noise filter that is provided in an electrical path between, for example, a power conversion device and a member on a low-voltage output side to suppress the conduction of electromagnetic noise.

[0002] For example, an electric vehicle is equipped with a high-voltage power supply of several hundred volts for driving the vehicle, auxiliary machinery driven by a low voltage of about 12 volts, and a power conversion device such as a DC / DC converter that converts the high-voltage output to a low-voltage output. A conductive member such as a bus bar is provided between the power conversion device and a component on the low-voltage output side. To suppress the conduction of electromagnetic noise through the bus bar, a noise filter using, for example, a ferrite core is provided in the electrical path between the power conversion device and the component on the low-voltage output side. The ferrite core is provided so as to surround the outer periphery of the bus bar.

[0003] When suppressing electromagnetic noise, Joule heat is generated in the ferrite core. It is preferable to dissipate the heat from the heated ferrite core so that the noise filter function can be maintained. The noise filter is attached to a housing made of metal, such as aluminum. The ferrite core is urged toward the housing to make it adhere to the housing. This allows the heat from the ferrite core to be dissipated to the housing. It also prevents the ferrite core from shifting. Japanese Patent Laid-Open Publication No. 2005-340458 and Japanese Patent No. 5304730 describe a configuration in which the ferrite core is urged toward the housing to make it adhere to the housing, thereby dissipating heat.

[0004] For example, consider a noise filter in which a ferrite core is molded as a single ring-shaped component and a bus bar is inserted into the hollow portion. When the ferrite core is a single ring-shaped component, cracks occur if the amount of deformation due to thermal expansion is large. To prevent cracks due to thermal expansion, for example, the ferrite core is divided into two components and a bus bar is inserted into the hollow portion between the two components. Japanese Patent No. 5304730 and Japanese Patent Laid-Open No. 2004-040055 describe a configuration in which the ferrite core is divided into two cores: an E-type core and an I-type core.

[0005] Conventional noise filters used in electric vehicles and other vehicles are attached to the housing during the process of attaching the circuit board to the control unit, for example. Conventional noise filters are assembled in the order of components closest to the housing. For example, the first core, the insulating sheet between the cores, the resin component with the bus bar inserted, and the second core are placed in this order, and the bus bar insert component is then screwed to the housing. In addition, a biasing member that biases the ferrite core toward the housing is screwed to the housing. This large number of components and assembly steps during assembly increases manufacturing costs and work time. In addition, it is necessary to provide bosses or other parts on the housing for attaching the biasing member, which places constraints on the housing design.

[0006] Therefore, there is a need for a noise filter that has a core with good heat dissipation properties and is easy to assemble.

[0007] According to one aspect of the present disclosure, a noise filter includes a first core and a second core made of ferrite. The second core faces the first core. The noise filter includes a conductive member, a case, and elastic means. The conductive member passes between the first core and the second core and has connection terminals at each end. The case accommodates the first core and the second core and allows the conductive member to pass through. The elastic means is provided in the case and can urge the first core toward the second core.

[0008] Therefore, the case allows the first core, the second core, and the conductive member to be assembled as an integrated module. This allows the noise filter to be assembled to a housing or the like as a module. This reduces the number of parts and assembly steps required when assembling the noise filter to a housing or the like. Furthermore, simply by assembling the case to the housing or the like, the elastic means can urge the first core toward the second core. This allows the second core to be pressed against the housing or the like to dissipate heat. This allows for easy assembly of the noise filter, and also allows for good heat dissipation from the first core and second core when assembled to the housing or the like.

[0009] According to another feature of the present disclosure, the protrusion of the second core protrudes from the opening of the case and, when the biasing force of the elastic means is generated, is pushed against the biasing force and moves into the case. Therefore, when the case is assembled to a housing or the like, the protrusion is pushed from the case side and is accompanied by a repulsive force. The protrusion is biased toward the housing or the like by the elastic means. As a result, the protrusion is in close contact with the housing or the like. This improves the heat dissipation effect of the first core and the second core.

[0010] According to another feature of the present disclosure, the support piece of the case protrudes from the case body. The conductive member is inserted into the retaining recess of the support piece. Therefore, the support piece with the retaining recess can position the conductive member that penetrates the case in a stable posture. Moreover, the conductive member can be positioned so that it is inserted between the first core and the second core but does not contact either the first core or the second core. Therefore, when assembling the noise filter to a housing or the like, the effort required to adjust the position of the conductive member relative to the first core and the second core is reduced. This improves the ease of assembling the noise filter.

[0011] According to another feature of the present disclosure, the support piece is provided with a claw. The claw prevents the conductive member from coming out of the holding recess. Therefore, the claw can hold the conductive member in a predetermined position. This makes it easier to assemble the noise filter to a housing or the like.

[0012] According to another feature of the present disclosure, the case includes a first case and a second case. The first case covers the first core and includes elastic means. The second case covers the second core and engages with the first case. Therefore, for example, the second core, the conductive member, and the first core are assembled to the second case in this order, and then the first case is engaged with the second case. This allows the second core, the conductive member, and the first core to be easily assembled as a single module. Moreover, simply by engaging the first case with the second case to form a module, the elastic means can be prepared to bias the first core toward the second core. Therefore, simply by assembling the modularized noise filter into a housing or the like, the first core and the second core are biased toward the housing and tightly attached to each other upon completion of assembly, allowing heat dissipation.

[0013] According to another feature of the present disclosure, the first case is made of a metal plate, and the elastic means utilizes the elastic force of the metal plate. Therefore, by providing the first case including the elastic means as a single component, the number of components can be reduced, thereby improving the ease of assembly of the noise filter.

[0014] According to another feature of the present disclosure, the flange of the first case extends to both sides of the elastic means. The flange has a mounting hole. Therefore, the first case can be stably attached to a housing or the like by using the flange. As a result, the elastic force of the elastic means of the first case biasing the first core and the second core can be stabilized.

[0015] According to another feature of the present disclosure, the engagement portion of the first case is provided between the elastic means and the flange and engages with the second case. Therefore, the engagement portion is provided near the flange that is assembled to the housing or the like. This stabilizes the elastic force of the first case around the engagement portion. This allows the first case and the second case to be stably engaged with each other.

[0016] According to another feature of the present disclosure, one of the first core and the second core has an opposing surface that is flat over its entire area facing the other core. An insulating sheet is placed on the opposing surface. The other core has a recess formed therein through which a conductive member is passed. Therefore, by providing a recess in one core through which a conductive member is passed, the opposing surface can be made flat over its entire area. This allows the insulating sheet to be stably held on the opposing surface. Furthermore, various modules can be easily prepared by changing the thickness of the insulating sheet depending on the electromagnetic noise.

[0017] 12. A perspective view of a noise filter according to a first embodiment. A top view of the noise filter. A front view of the noise filter. An exploded perspective view of the noise filter as seen from above. An exploded perspective view of the noise filter as seen from below. A sectional view taken along line VI-VI in FIG. 2. A perspective view of a noise filter according to a second embodiment. An exploded perspective view of the noise filter as seen from above. An exploded perspective view of the noise filter as seen from below. A sectional view taken along line X-X in FIG. 7. A perspective view of a noise filter according to a third embodiment. A top view of the noise filter. An exploded perspective view of the noise filter. A sectional view taken along line XIV-XIV in FIG. 12. A sectional view of a noise filter according to a fourth embodiment.

[0018] [First Embodiment] A first embodiment of the present disclosure will be described with reference to Figures 1 to 6. In this disclosure, a noise filter 1 provided in, for example, a plug-in hybrid vehicle or an electric vehicle is exemplified. An electric vehicle or the like has a power conversion device that converts a high-voltage output of several hundred volts from a power source into a low-voltage output of, for example, 12 volts. The noise filter 1 is provided on an electrical path between the power conversion device and auxiliary equipment or the like on the low-voltage output side. In the following description, the up-down, front-rear, left-right directions of the noise filter 1 are defined as those shown in the drawings.

[0019] 1, 2, and 4, the noise filter 1 includes a bus bar 2 as a conductive member having connection terminals at both ends. The bus bar 2 is formed in a plate shape with its thickness extending in the vertical direction and extending generally in the front-to-rear direction. The bus bar 2 has a connection terminal 2a at its front end that is connected to the power converter side. The bus bar 2 has a connection terminal 2b at its rear end that is connected to the low-voltage output side. Holes for inserting male screws 6 are formed in the connection terminals 2a and 2b. The connection terminals 2a and 2b are fastened to mating terminals (not shown in FIG. 1) with the male screws 6 to form an electrical path, thereby being fixed and electrically connected.

[0020] As shown in Figure 4, a narrow portion 2c with a small lateral width is provided in the center of the busbar 2 in the front-to-rear direction. The narrow portion 2c is inserted between a first core 3 and a second core 4, which will be described later. The busbar 2 is provided with wide portions 2d on both the front and rear sides of the narrow portion 2c, each of which has a lateral width greater than that of the narrow portion 2c. The side surface of the narrow portion 2c and the side surface of the front wide portion 2d are connected by an inclined surface 2e. The inclined surface 2e extends in a plane inclined left-to-right with respect to the front-to-rear direction.

[0021] 1 and 4 , the noise filter 1 has a substantially rectangular box-shaped case 10. The bus bar 2 penetrates the case 10 in the front-rear direction and is supported by the case 10. The case 10 has an upper first case 11 and a lower second case 13. The case 10 is formed by assembling the first case 11 and the second case 13 together. The first case 11 is made of, for example, an elastic metal plate, such as iron or aluminum. The first case 11 may also be made of, for example, a highly elastic synthetic resin. The second case 13 is made of, for example, a highly insulating synthetic resin.

[0022] As shown in FIGS. 4 to 6 , the noise filter 1 has a first core 3, a second core 4, and an insulating sheet 5 housed in a case 10. The first core 3 and the second core 4 are made of a magnetic material, such as ferrite. The first core 3 is located above the second core 4. The first core 3 is primarily covered by the first case 11 and partially covered by the second case 13. The second core 4 is housed in and covered by the second case 13. The insulating sheet 5 is made of, for example, a synthetic resin with high insulating properties. The insulating sheet 5 is sandwiched between the lower surface 3 b of the first core 3 and the upper surface 4 a of the second core 4. The two-piece structure of the first core 3 and the second core 4 makes it possible to adjust the magnetic permeability by adjusting the gap between the cores, for example, by changing the thickness of the insulating sheet 5.

[0023] As shown in Figures 4 to 6, the first core 3 is U-shaped when viewed from the front. The first core 3 is rectangular when viewed from above. The top surface 3a of the first core 3 is a horizontal, flat surface. A U-shaped groove-shaped recess 3c is provided in the lower center of the first core 3. The recess 3c is recessed upward from the bottom surface 3b of the first core 3. The recess 3c penetrates the first core 3 in the front-to-rear direction. The bottom surface 3b of the first core 3 is divided into left and right halves by the recess 3c. The left and right bottom surfaces 3b extend horizontally and flatly at the same height.

[0024] As shown in Figures 4 to 6, the second core 4 has an I-shape elongated from side to side when viewed from the front. When viewed from above, the second core 4 has a rectangular shape of approximately the same size as the first core 3. The top surface 4a of the second core 4 is horizontally flat. The lower part of the second core 4 is formed in a stepped shape. The stepped surface 4b extends horizontally in a flat shape with approximately the same outer circumferential shape as the top surface 4a. The protrusion 4c protrudes downward from the step surface 4b with an outer circumferential shape slightly smaller than that of the step surface 4b. The bottom surface of the protrusion 4c extends horizontally in a flat shape. The second core 4 has four corners 4d on its side. The corners 4d are chamfered in an arc shape between the top surface 4a and the step surface 4b. When viewed from above, the insulating sheet 5 has approximately the same rectangular shape as the top surface 4a of the second core 4.

[0025] As shown in Figures 1 to 3, the first case 11 is U-shaped when viewed from the front, with both ends of the U-shape extending outward to the left and right. The first case 11 is rectangular when viewed from above. The first case 11 has a top surface 11a, a pair of upright surfaces 11b, and a pair of flanges 11c. The top surface 11a is rectangular and covers the upper part of the case body 10a. The top surface 11a extends horizontally in a flat shape. The pair of upright surfaces 11b extend downward in a flat shape from each of the left and right ends of the top surface 11a. The right flange 11c extends horizontally and flatly to the right from the lower end of the right upright surface 11b. The left flange 11c extends horizontally and flatly to the left from the lower end of the left upright surface 11b. The lower surfaces of the pair of left and right flanges 11c are approximately the same height. The height of each flange 11c may be different depending on the installation space required for the device. Furthermore, the horizontal extension lengths of the flanges 11c may be different between the left and right sides. The top surface 11a, the pair of upright surfaces 11b, and the pair of flanges 11c are formed by deforming a single plate-like member by, for example, pressing or bending.

[0026] As shown in Figures 1, 4, and 5, each upright surface 11b is provided with an engaging portion 11e penetrating in the left-right direction. The engaging portion 11e is provided as a rectangular through-hole at approximately the center of the upright surface 11b in the front-rear and up-down directions. Each flange 11c is provided with a mounting hole 11f penetrating in the up-down direction. The mounting hole 11f has an oval shape that is long in the left-right direction. A male screw 7 is inserted into each of the two mounting holes 11f. The first case 11 can be fixed to the housing 50 by screwing the two male screws 7 into the housing 50 (see Figure 6).

[0027] As shown in Figures 3, 4, and 6, the first case 11 has an elastic means (elastic piece) 12 on its top surface 11a. The elastic means 12 is a leaf spring member made of the same material as the first case 11 and integrally formed therewith. The elastic means 12 can urge the first core 3 in the case body 10a downward. A rectangular notch 11d is formed in the top surface 11a. The elastic means 12 is provided within the notch 11d. The elastic means 12 is connected to the top surface 11a at a base 12a on the left end. The base 12a is located near the connection between the top surface 11a and the left upright surface 11b. The elastic means 12 extends cantilevered to the right from the base 12a. The elastic means 12 has a tip 12b at its right end. As shown in Figure 1, the tip 12b is located approximately above the right end of the support piece 13d of the second case 13. The tip 12b can elastically move up and down with the base 12a as a fulcrum. The elastic means 12 has a pressing portion 12c slightly to the left of the tip 12b. The pressing portion 12c has a downwardly convex shape. The pressing portion 12c abuts against the upper surface 3a of the first core 3. The pressing portion 12c urges the first core 3 downward in response to the elastic deformation of the elastic means 12.

[0028] As shown in Figures 4 and 5, the second case 13 has a rectangular box shape. The top of the second case 13 is open upward. An opening 13e penetrating vertically is provided in the center of the bottom surface 13a of the second case 13. The opening 13e has a rectangular shape that is slightly larger than the outer periphery of the protruding portion 4c of the second core 4. The protruding portion 4c of the second core 4 housed in the second case 13 can protrude downward through the opening 13e. The second case 13 has side surfaces 13b on the front and rear sides. The second case 13 has side surfaces 13c on the right and left sides. The side surfaces 13b and 13c each extend upward substantially perpendicularly from the bottom surface 13a. The pair of side surfaces 13b and the pair of side surfaces 13c are interconnected to form a rectangular box-shaped space. When viewed from above, this box-shaped space is approximately the same size as or slightly larger than the outer periphery of the second core 4.

[0029] As shown in FIGS. 1 and 4 , a through hole 13f is provided at the center of the upper portion of each of the pair of side surfaces 13b. The through hole 13f is formed by cutting out a U-shape downward from the upper end of the side surface 13b. The pair of through holes 13f are aligned front to back, forming a passage that penetrates the second case 13 in the front-to-rear direction. The bus bar 2 is inserted through this passage. The second case 13 has a pair of front and rear support pieces 13d. The front support piece 13d extends forward approximately horizontally from the front side surface 13b. The front support piece 13d extends forward from the bottom (lower part) of the U-shaped through hole 13f. The rear support piece 13d extends rearward approximately horizontally from the rear side surface 13b. The rear support piece 13d extends rearward from the bottom (lower part) of the U-shaped through hole 13f.

[0030] As shown in FIGS. 1, 3, and 4, a groove-shaped retaining recess 13h extending in the front-rear direction is formed on the upper surface of the support piece 13d. The bus bar 2 is inserted into the retaining recess 13h. This positions the bus bar 2 in the left-right direction relative to the pair of support pieces 13d. A sloped portion 13k is formed on a part of the side surface of the retaining recess 13h, sloped in the left-right direction relative to the front-rear direction. The sloped surface 2e of the bus bar 2 faces and abuts against the sloped portion 13k. This positions the bus bar 2 in the front-rear direction relative to the pair of support pieces 13d. A claw 13i is formed on the upper surface of the support piece 13d adjacent to the retaining recess 13h. The tip of the claw 13i extends in the left-right direction so as to cover the upper part of the retaining recess 13h. The claw 13i is hooked onto the upper surface of the bus bar 2 inserted into the retaining recess 13h. This prevents the bus bar 2 from coming off the retaining recess 13h.

[0031] As shown in Figures 1, 4, and 6, a claw-shaped engaged portion 13g is provided on the upper portion of the side surface 13c. The engaged portion 13g is triangular when viewed from the front. The engaged portion 13g protrudes in the left-right direction as it extends downward. The engaged portion 13g provided on the right side surface 13c protrudes to the right. The engaged portion 13g provided on the left side surface 13c protrudes to the left. The engaged portion 13g can enter the engaging portion 11e of the first case 11. Each of the pair of engaged portions 13g enters the engaging portion 11e of the first case 11 while elastically deforming the first case 11. This allows the first case 11 and the second case 13 to engage with each other. When the engaging portion 11e and the engaged portion 13g are engaged with each other, the first case 11 and the second case 13 preferably have an engagement relationship that prevents them from coming loose but allows some relative movement.

[0032] Next, the assembly procedure for the noise filter 1 will be described with reference to Figures 4 to 6. First, the second core 4 is inserted into the second case 13 with the protruding portion 4c positioned downward. The stepped surface 4b abuts against the lower surface 13a, preventing the second core 4 from slipping out. An insulating sheet 5 is placed on the upper surface 4a of the second core 4. The bus bar 2 is placed on the insulating sheet 5 with the bus bar 2 extending in the front-to-rear direction. The bus bar 2 is inserted into the retaining recess 13h of the support piece 13d and held by the claws 13i. The first core 3 is then placed on the insulating sheet 5 with the bus bar 2 inserted into the recess 3c. The first case 11 is then placed over the first core 3. The engaging portion 11e of the first case 11 is elastically engaged with the engaged portion 13g of the second case 13. This allows the bus bar 2, first core 3, second core 4, insulating sheet 5, and case 10 to be assembled as a single module.

[0033] When assembled as a module, it is preferable that the first case 11 and the second case 13 move relative to each other. Furthermore, it is preferable that the elastic means 12 does not elastically deform and does not generate a biasing force. This is because the noise filter 1 needs to be modularized to accommodate variations in the positions of the bus bar 2, housing 50, screw holes, electrical paths, etc. Furthermore, the noise filter 1 needs to be fixed to the housing 50 with screws while the first core 3 and the second core 4 are securely biased against the bottom surface 50a of the housing 50 and in close contact with it. Therefore, it is preferable that the biasing force of the elastic means 12 begins to be generated when the male screw 7 begins to be tightened. The first case 11, the second case 13, the first core 3, and the second core 4 can move relative to each other to accommodate variations in the positions of the bus bar 2, housing 50, screw holes, electrical paths, etc. Of course, if there is no problem in accommodating variations, the first core 3 and the second core 4 may already be biased by the elastic means 12 in the modular state before assembly into the housing 50. In this case, the displacement caused when the protruding portion 4c is pressed against the bottom surface 50a generates an additional biasing force in the elastic means 12, and the first core 3 and the second core 4 are pressed against the bottom surface 50a.

[0034] When assembling the noise filter 1 to, for example, an aluminum housing 50, first, the male screw 7 is inserted into the mounting hole 11f of the first case 11. The male screw 7 is then screwed into the threaded hole of the housing 50. When the male screw 7 begins to be tightened, the protrusion 4c of the second core 4 protrudes outward from the case body 10a through the opening 13e of the second case 13. When the male screw 7 is further tightened, the case 10 is pressed downward toward the bottom surface 50a of the housing 50. The lower surface 13a of the second case 13 moves to a height where it generally abuts against the bottom surface 50a. The protrusion 4c of the second core 4 protruding from the opening 13e is pressed upward by the bottom surface 50a. At this time, the upper surface 3a of the first core 3 abuts against the pressing portion 12c of the elastic means 12 provided on the first case 11. When the elastic means 12 elastically deforms, a biasing force that biases the first core 3 downward begins to be generated. The second core 4 also begins to receive the biasing force of the elastic means 12 via the first core 3 and the insulating sheet 5. As a result, the protruding portion 4c is pushed upward by the bottom surface 50a against the biasing force of the elastic means 12. The protruding portion 4c moves upward into the case body 10a as shown by the imaginary line.

[0035] The more the male screw 7 is tightened, the stronger the biasing force of the elastic means 12 becomes. When the noise filter 1 is completely assembled, the biasing force of the elastic means 12 causes the lower surface of the protrusion 4c to adhere tightly to the bottom surface 50a. This ensures that heat from the second core 4 is dissipated to the bottom surface 50a of the housing 50. The first core 3 and the second core 4 generate Joule heat when suppressing electromagnetic noise caused by current flowing through the bus bar 2. Because the biasing force of the elastic means 12 presses the first core 3 from above, heat generated in the first core 3 is also reliably dissipated to the second core 4 via the insulating sheet 5. This ensures that heat is dissipated from the first core 3 and the second core 4. Heat is also conducted from the top surface 3a of the first core 3 where the elastic means 12 abuts, and is dissipated to the housing 50 via the first case 11.

[0036] The interior of the case body 10a allows the first core 3, the insulating sheet 5, and the second core 4 to move up and down, but restricts their movement in the front-rear or left-right directions. This prevents the first core 3, the insulating sheet 5, and the second core 4 from shifting in their positions in the front-rear or left-right directions during assembly. The bus bar 2 inserted between the first core 3 and the second core 4 is held by the support piece 13d at a height that prevents it from contacting both the first core 3 and the second core 4, whether the first core 3 and the second core 4 are positioned downward (solid lines in FIG. 6 ) or upward (phantom lines in FIG. 6 ). This prevents current flowing through the bus bar 2 from flowing to the first core 3 or the second core 4.

[0037] After the case 10 is assembled to the housing 50, the male screws 6 are inserted into the connection terminals 2a, 2b. The male screws 6 are screwed into the mating terminals (not shown in FIG. 1) to form an electrical path. The connection terminals 2a, 2b are electrically connected to the electrical path. This completes the assembly of the noise filter 1. The assembly of the case 10 with the male screws 7 and the assembly of the bus bar 2 with the male screws 6 may be reversed. In either case, the noise filter 1 can be assembled to the housing 50 simply by screwing in the four male screws.

[0038] As described above, the noise filter 1 has a first core 3 and a second core 4 made of ferrite, as shown in FIGS. 3, 4, and 6. The second core 4 faces the first core 3. The noise filter 1 has a bus bar (conductive member) 2, a case 10, and elastic means 12. The bus bar 2 passes between the first core 3 and the second core 4 and has connection terminals 2a, 2b at each end. The case 10 houses the first core 3 and the second core 4 and allows the bus bar 2 to pass through. The elastic means 12 is provided in the case 10 and can urge the first core 3 toward the second core 4.

[0039] Therefore, the case 10 allows the first core 3, the second core 4, and the bus bar 2 to be assembled as an integrated module. This allows the noise filter 1 to be assembled to the housing 50 as a module. This reduces the number of parts and assembly steps required when assembling the noise filter 1 to the housing 50. Furthermore, simply by assembling the case 10 to the housing 50, the elastic means 12 can urge the first core 3 toward the second core 4. This allows the second core 4 to be pressed against the bottom surface 50a of the housing 50, allowing heat to be dissipated. This allows for easy assembly of the noise filter 1, and also allows for good heat dissipation from the first core 3 and the second core 4 when assembled to the housing 50.

[0040] As shown in Figure 6, the protruding portion 4c of the second core 4 protrudes from the opening 13e of the case 10, and when the biasing force of the elastic means 12 is generated, it is pushed against the biasing force and moves into the case 10. Therefore, when the case 10 is assembled to the housing 50, the protruding portion 4c is pushed by the bottom surface 50a of the housing 50 and is accompanied by a repulsive force. The protruding portion 4c is biased toward the bottom surface 50a of the housing 50 by the elastic means 12. As a result, the protruding portion 4c is in close contact with the bottom surface 50a of the housing 50. This improves the heat dissipation effect of the first core 3 and the second core 4.

[0041] As shown in Figures 1 and 4, the support piece 13d of the case 10 protrudes from the case body 10a. The bus bar 2 is inserted into the retaining recess 13h of the support piece 13d. Therefore, the support piece 13d with the retaining recess 13h allows the bus bar 2, which penetrates the case 10, to be positioned in a stable posture. Furthermore, the bus bar 2 can be positioned so that it is inserted between the first core 3 and the second core 4 without contacting either the first core 3 or the second core 4. Therefore, when assembling the noise filter 1 to the housing 50 (see Figure 6), the effort required to adjust the position of the bus bar 2 relative to the first core 3 and the second core 4 is reduced. This improves the ease of assembly of the noise filter 1.

[0042] As shown in Figures 1, 3, and 4, the support piece 13d is provided with a claw 13i. The claw 13i prevents the bus bar 2 from coming out of the holding recess 13h. Therefore, the claw 13i can hold the bus bar 2 in a predetermined position. This makes it easier to assemble the noise filter 1 into the housing 50 (see Figure 6).

[0043] As shown in FIGS. 4 to 6 , the case 10 includes a first case 11 and a second case. The first case 11 covers the first core 3 and is provided with elastic means 12. The second case 13 covers the second core 4 and engages with the first case 11. Therefore, for example, the second core 4, the bus bar 2, and the first core 3 are assembled to the second case 13 in this order, and then the first case 11 is engaged with the second case 13. This allows the second core 4, the bus bar 2, and the first core 3 to be easily assembled as a single module. Moreover, simply engaging the first case 11 with the second case 13 to form a module enables the elastic means 12 to bias the first core 3 toward the second core 4. Therefore, simply assembling the modularized noise filter 1 into the housing 50 allows the first core 3 and the second core 4 to be biased toward the housing 50 and to be in close contact with each other, allowing heat dissipation upon completion of assembly.

[0044] Furthermore, the first case 11 and the second case 13 are engaged to move relative to each other in the modular state, so that when the modularized noise filter 1 is assembled to the housing 50 with screws, it can be fixed while absorbing variations in relative positional misalignment between the bus bar 2 and the electrical path, the first core 3, the second core 4 and the bottom surface 50a, the noise filter 1 and the housing 50, etc.

[0045] 4 to 6, the first case 11 is made of a metal plate, and the elastic means 12 utilizes the elastic force of the metal plate. Therefore, by providing the first case 11 including the elastic means 12 as a single component, the number of components can be reduced, thereby improving the ease of assembly of the noise filter 1.

[0046] 3 and 6, the flange 11c of the first case 11 protrudes on both sides of the elastic means 12. Mounting holes 11f are formed in the flange 11c. Therefore, the first case 11 can be stably assembled to the housing 50 using the flange 11c. This stabilizes the elastic force with which the elastic means 12 of the first case 11 biases the first core 3 and the second core 4.

[0047] 4 to 6, the engaging portion 11e of the first case 11 is provided between the elastic means 12 and the flange 11c and engages with the second case 13. Therefore, the engaging portion 11e is provided near the flange 11c that is assembled to the housing 50. This stabilizes the elastic force of the first case 11 around the engaging portion 11e. This allows the first case 11 and the second case 13 to be engaged with each other in a stable manner.

[0048] As shown in Figures 4 and 6, the second core 4 has a flat upper surface (facing surface) 4a facing the first core 3. An insulating sheet 5 is placed on the upper surface 4a. The first core 3 has a recess 3c through which the bus bar 2 passes. Therefore, by providing the recess 3c through which the bus bar 2 passes in the first core 3, the upper surface 4a of the second core 4 can be made flat over its entire area. This allows the insulating sheet 5 to be stably held by the upper surface 4a. Furthermore, various modules can be easily prepared by changing the thickness of the insulating sheet 5 depending on the electromagnetic noise.

[0049] Second Embodiment A second embodiment of the present disclosure will be described with reference to FIGS. 7 to 10 . A noise filter 20 of the second embodiment has a substantially rectangular box-shaped case 21 instead of the case 10 of the first embodiment shown in FIG. 1 . The case 21 includes a first case 22 that covers the first core 3 and a second case 24 that covers the second core 4. The case 21 is formed by assembling the first case 22 and the second case 24 together. An elastic means 23 made of the same material is integrally provided on the first case 22. The first case 22 and the elastic means 23 are made, for example, of elastic metal plates, such as iron or aluminum. The first case 22 and the elastic means 23 may also be made, for example, of highly elastic synthetic resin. The second case 24 is made, for example, of highly insulating synthetic resin. In the following description, only differences from the first embodiment will be described in detail.

[0050] As shown in Figures 7 to 9, the first case 22 is U-shaped when viewed from the front, with both ends of the U-shape extending outward to the left and right. When viewed from above, the first case 22 is rectangular. The first case 22 has an upper surface 22a, a pair of upright surfaces 22b, and a pair of flanges 22c. The shapes and arrangement of the upper surface 22a, the upright surfaces 22b, and the flanges 22c are the same as those of the first case 11 of the first embodiment (see Figure 1). The heights of the lower surfaces of the pair of left and right flanges 22c are approximately the same.

[0051] As shown in Figures 7 to 9, each upright surface 22b has a notch 22e penetrating it in the left-right direction. The notch 22e is a rectangular through-hole located approximately in the center of the upright surface 22b in the front-rear and up-down directions. An engaging portion 22f is provided within the notch 22e of each upright surface 22b. The engaging portion 22f is a leaf spring integral with the upright surface 22b. The engaging portion 22f extends upward in a cantilevered manner from the lower end of the notch 22e. The vicinity of the tip of the engaging portion 22f protrudes toward the inside of the case main body 21a. The convex portion of this engaging portion 22f elastically engages with an engaged portion 24g of the second case 24, which will be described later. In other words, the convex-concave relationship between the engaging portion 22f and the engaged portion 24g is reversed from that in the first embodiment.

[0052] 8 to 10, each flange 22c is provided with a mounting hole 22g that penetrates in the vertical direction. The mounting holes 22g are circular. A male screw 7 is inserted into each of the two mounting holes 22g. The first case 22 can be fixed to the housing 50 by screwing the two male screws 7 into the housing 50.

[0053] As shown in Figures 7 to 10, the first case 22 has an elastic means 23 on its top surface 22a. The elastic means 23 is a leaf spring member integral with the first case 22. The elastic means 23 can bias the first core 3 in the case body 21a downward. A rectangular notch 22d is provided in the top surface 22a. The elastic means 23 is provided within the notch 22d. The elastic means 23 is connected to the top surface 22a at a base 23a on its left end. The base 23a is located approximately above the left end of a support piece 24d (described below). The elastic means 23 has a tip 23b on its right end. The tip 23b is located approximately above the right end of the support piece 24d. The tip 23b can elastically move up and down with the base 23a as a fulcrum. The elastic means 23 has a pressing portion 23c slightly to the left of the tip 23b. The pressing portion 23c has a downwardly convex shape and abuts against the upper surface 3a of the first core 3. The pressing portion 23c urges the first core 3 downward in response to the elastic deformation of the elastic means 23.

[0054] As shown in Figures 8 to 10, the second case 24 has a rectangular box shape. The top of the second case 24 opens upward. An opening 24e penetrating in the vertical direction is provided in the center of the bottom surface 24a of the second case 24. The opening 24e has a rectangular shape that is slightly larger than the outer periphery of the protruding portion 4c of the second core 4. The protruding portion 4c of the second core 4 housed in the second case 24 can protrude downward through the opening 24e. The front and rear side surfaces 24b and the left and right side surfaces 24c of the second case 24 each extend upward substantially perpendicularly from the bottom surface 24a. The pair of side surfaces 24b and the pair of side surfaces 24c are connected to each other to form a rectangular box-shaped space. This box-shaped space is approximately the same size as or slightly larger than the outer periphery of the second core 4 when viewed from above. An arc-shaped curved surface 24i is provided at the lower part of the connecting portion between the side surfaces 24b and 24c. The curved surface 24 i faces the chamfered shape of the corner 4 d of the second core 4 .

[0055] As shown in Figures 7 and 8, a through hole 24f is provided at the center of the upper portion of each of the pair of side surfaces 24b. The through hole 24f is formed by a U-shaped notch extending downward from the upper end of the side surface 24b. The pair of through holes 24f are aligned front to back, forming a passage that penetrates the second case 24 in the front-to-rear direction. The bus bar 2 is inserted through this passage. The second case 24 has a pair of front and rear support pieces 24d. The front support piece 24d extends substantially horizontally forward from the bottom of the U-shaped through hole 24f on the front side surface 24b. The rear support piece 24d extends substantially horizontally rearward from the bottom of the U-shaped through hole 24f on the rear side surface 24b.

[0056] 7 and 8 , a groove-shaped holding recess 24h extending in the front-rear direction is formed in the upper surface of the support piece 24d. The bus bar 2 is inserted into the holding recess 24h. A sloped portion 24k that slopes in the left-right direction with respect to the front-rear direction is formed on a part of the side surface of the holding recess 24h. The sloped surface 2e of the bus bar 2 faces and abuts against the sloped portion 24k. Thus, the bus bar 2 is positioned in the left-right and front-rear directions relative to the pair of support pieces 24d by the holding recess 24h and the sloped portion 24k.

[0057] 7 to 10, rectangular hole-shaped engaged portions 24g penetrating in the left-right direction are provided at the top of the side surface 24c. A pair of engaging portions 22f of the first case 22 enters the pair of engaged portions 24g and elastically engages with them. This allows the first case 22 and the second case 24 to be engaged with each other.

[0058] Next, the assembly procedure for the noise filter 20 will be described with reference to Figures 8 to 10. First, the second core 4 is inserted into the second case 24 with the protruding portion 4c positioned downward. The stepped surface 4b abuts against the lower surface 24a, preventing the second core 4 from slipping out. An insulating sheet 5 is placed on the upper surface 4a of the second core 4. The bus bar 2 is placed on the insulating sheet 5 with the bus bar 2 extending in the front-to-rear direction. The bus bar 2 is inserted into the retaining recess 24h of the support piece 24d. The first core 3 is then placed on the insulating sheet 5 with the bus bar 2 inserted into the recess 3c. The first case 22 is then placed over the first core 3. The engaging portion 22f of the first case 22 is elastically engaged with the engaged portion 24g of the second case 24. This completes the assembly of the bus bar 2, first core 3, second core 4, insulating sheet 5, and case 21 into a single module. The assembly relationship between the core and case when modularized is the same as in the first embodiment.

[0059] When assembling the noise filter 20 to, for example, an aluminum housing 50, first, the male screw 7 is inserted into the mounting hole 22g of the first case 22. The male screw 7 is then screwed into the threaded hole of the housing 50. When the male screw 7 begins to be tightened, the protrusion 4c of the second core 4 protrudes outward from the case body 21a through the opening 24e of the second case 24. When the male screw 7 is further tightened, the case 21 is pressed downward toward the bottom surface 50a of the housing 50. The lower surface 24a of the second case 24 moves to a height where it generally abuts against the bottom surface 50a. The protrusion 4c of the second core 4 protruding from the opening 24e is pressed upward by the bottom surface 50a. At this time, the upper surface 3a of the first core 3 abuts against the pressing portion 23c of the elastic means 23 provided on the first case 22. When the elastic means 23 elastically deforms, a biasing force that biases the first core 3 downward begins to be generated. The second core 4 also begins to receive the biasing force of the elastic means 23 via the first core 3 and the insulating sheet 5. As a result, the protruding portion 4c is pushed upward by the bottom surface 50a against the biasing force of the elastic means 23. The protruding portion 4c moves upward into the case main body 21a as shown by the imaginary line.

[0060] The more the male screw 7 is tightened, the stronger the biasing force of the elastic means 23 becomes. When the noise filter 20 is completely assembled, the biasing force of the elastic means 23 causes the lower surface of the protrusion 4c to adhere tightly to the bottom surface 50a of the housing 50. This ensures that heat generated in the second core 4 is dissipated to the bottom surface 50a of the housing 50. Because the biasing force of the elastic means 23 presses the first core 3 from above, heat generated in the first core 3 is also dissipated reliably to the second core 4 via the insulating sheet 5. Heat is also conducted from the top surface 3a of the first core 3 where the elastic means 23 abuts, and can be dissipated to the housing 50 via the first case 22.

[0061] The interior of the case body 21a allows the first core 3, the insulating sheet 5, and the second core 4 to move up and down, but restricts movement in the front-rear or left-right directions. The bus bar 2 inserted between the first core 3 and the second core 4 is held by the support piece 24d at a height that does not contact either the first core 3 or the second core 4, whether the first core 3 and the second core 4 are positioned downward (solid lines in FIG. 10 ) or upward (phantom lines in FIG. 10 ). This prevents the current flowing through the bus bar 2 from flowing to the first core 3 or the second core 4.

[0062] Before or after assembling the case 21 to the housing 50 with the male screws 7, the male screws 6 are inserted into the connection terminals 2a, 2b. The male screws 6 are screwed into mating terminals (not shown in FIG. 7) to form electrical paths. The connection terminals 2a, 2b are electrically connected to the electrical paths. This completes the assembly of the noise filter 20. The noise filter 20 described above provides the same effects as the noise filter 1 of the first embodiment (see FIG. 1).

[0063] A third embodiment of the present disclosure will be described with reference to Figures 11 to 14. A noise filter 30 of the third embodiment has a substantially rectangular box-shaped case 31 instead of the case 10 of the first embodiment shown in Figure 1. An elastic means 32 is integrally provided on the case 31 and made of the same material. The case 31 and the elastic means 32 are made of, for example, a synthetic resin that is highly elastic and insulating. In the following description, only the differences from the first embodiment will be described in detail.

[0064] As shown in Figures 11 to 13, the case 31 is open toward the front. An opening 31g is provided in the center of the lower surface 31b of the case 31. The opening 31g penetrates the lower surface 31b in the vertical direction and communicates with the front opening of the case main body 31a. The opening 31g is rectangular and slightly larger than the outer periphery of the protruding portion 4c of the second core 4. The protruding portion 4c of the second core 4 housed in the case main body 31a can protrude downward from the opening 31g. The rear side surface 31c and the left and right side surfaces 31d of the case 31 each extend upward approximately perpendicularly from the lower surface 31b. A pair of side surfaces 31d is connected to each of the left and right ends of the side surface 31c.

[0065] As shown in Figures 11 to 14, the case 31 has a pair of left and right flanges 31e. The right flange 31e extends substantially horizontally to the right from approximately the vertical center of the right side surface 31d. The left flange 31e extends substantially horizontally to the left from approximately the vertical center of the left side surface 31d. The lower surfaces of the pair of left and right flanges 31e are substantially the same height. A cylindrical boss portion 31m protrudes downward from the lower surface of the flange 31e. The boss portion 31m is provided in place of the male screw 7 (see Figure 1). The case 31 can be fixed to the housing 50 by assembling the boss portion 31m into a predetermined hole in the housing 50.

[0066] As shown in Figures 11 to 14, the case 31 has a pair of left and right elastic means 32. The pair of left and right elastic means 32 are provided symmetrically and have the same shape. The elastic means 32 has a base 32a connected to the upper part of the side surface 31d. The elastic means 32 is cantilevered and extends from the base 32a to the tip 32b. When viewed from the front, the elastic means 32 has a triangular shape that tapers from the base 32a to the tip 32b. The lower surface of the elastic means 32 is approximately horizontal. When viewed from above, the elastic means 32 is rectangular. The right elastic means 32 extends from the base 32a to the left tip 32b. The left elastic means 32 extends from the base 32a to the right tip 32b. The elastic means 32 elastically deforms in the vertical direction with the base 32a as a fulcrum. The tip (pressing portion) 32b of the elastic means 32 can be brought into contact with the upper surface 3a of the first core 3 housed in the case body 31a and urged downward.

[0067] As shown in Figures 11 to 13, a through hole 31h is provided in the upper center of the side surface 31c. The through hole 31h is formed as a U-shaped notch extending downward from the upper end of the side surface 31c. The bus bar 2 passes through the through hole 31h in the front-to-rear direction. A support piece 31f is provided in the center of the case body 31a. The support piece 31f extends approximately horizontally forward from the bottom of the U-shaped through hole 31h on the side surface 31c. A groove-shaped holding recess 31i extending in the front-to-rear direction is recessed in the upper surface of the support piece 31f. The bus bar 2 is inserted into the holding recess 31i for positioning. A claw 31j is provided on the upper surface of the support piece 31f adjacent to the holding recess 31i. The tip of the claw 31j extends in the left-to-right direction above the holding recess 31i. The claw 31j is hooked onto the upper surface of the bus bar 2 inserted into the holding recess 31i. This can prevent the bus bar 2 from coming off the holding recess 31i.

[0068] 13 and 14 , a step 31k is provided on the inner wall of the side surface 31c, 31d. The area below the step 31k is sized to accommodate the second core 4. The area above the step 31k is sized to be smaller than the second core 4 but large enough to accommodate the first core. Movement of the top surface 4a of the second core 4 above the step 31k is restricted.

[0069] Next, the assembly procedure for the noise filter 30 will be described with reference to Figures 13 and 14. First, the second core 4 is inserted from the front to the rear of the case 31 with the protruding portion 4c positioned downward. The stepped surface 4b abuts against the lower surface 31b, preventing the second core 4 from slipping out. An insulating sheet 5 is placed on the upper surface 4a of the second core 4. The insulating sheet 5 is inserted below the support piece 31f and the stepped portion 31k. The stepped portion 31k prevents the second core 4 and the insulating sheet 5 from moving upward. The bus bar 2 is inserted into the retaining recess 31i of the support piece 31f with the bus bar 2 extending in the front-rear direction. The first core 3 is inserted from the front to the rear of the case 31 so that it rests on the insulating sheet 5 with the bus bar 2 inserted into the recess 3c. The upper surface 3a of the first core 3 is biased downward by the elastic means 32. In this way, the bus bar 2, the first core 3, the second core 4, the insulating sheet 5, and the case 31 are assembled as one module.

[0070] When assembling the noise filter 30 into, for example, an aluminum housing 50, the boss 31m is first inserted into the hole in the housing 50. At the stage where the boss 31m begins to be inserted, the protrusion 4c of the second core 4 protrudes outward from the opening 31g of the case body 31a. When the boss 31m is further inserted, the case 31 moves downward toward the bottom surface 50a of the housing 50. The protrusion 4c of the second core 4 protruding from the opening 31g is pressed against the bottom surface 50a against the biasing force of the elastic means 32.

[0071] Meanwhile, the top surface 3a of the first core 3 abuts against the tip 32b of the elastic means 32 provided on the case 31. The first core 3 is biased downward by the elastic means 32. The second core 4 is also subjected to the biasing force of the elastic means 32 via the first core 3 and the insulating sheet 5. The biasing force of the elastic means 32 causes the lower surface of the protrusion 4c to adhere closely to the bottom surface 50a. Moreover, the step portion 31k restricts the upward movement of the second core 4. Therefore, heat generated in the second core 4 can be reliably dissipated to the bottom surface 50a of the housing 50. Because the biasing force of the elastic means 32 presses the first core 3 from above, heat generated in the first core 3 can also be reliably dissipated to the second core 4 via the insulating sheet 5. Furthermore, although heat dissipation is lower than that of the metallic elastic means 12, 23 and first case 11, 22 of the first and second embodiments, heat can still be dissipated via the elastic means 32 and the case 31.

[0072] The bus bar 2 inserted between the first core 3 and the second core 4 is held by the support piece 31f at a height that prevents it from contacting either the first core 3 or the second core 4. This prevents the current flowing through the bus bar 2 from flowing to the first core 3 or the second core 4. Before or after assembling the case 31 to the housing 50 at the boss portion 31m, male screws 6 are inserted into the connection terminals 2a, 2b. The male screws 6 are screwed into mating terminals (not shown in FIG. 11 ) to form an electrical path. The connection terminals 2a, 2b are electrically connected to the electrical path. This completes the assembly of the noise filter 30. The noise filter 30 described above provides the same effects as the noise filter 1 of the first embodiment (see FIG. 1 ).

[0073] [Fourth Embodiment] A fourth embodiment of the present disclosure will be described with reference to FIG. 15 . A noise filter 40 of the fourth embodiment has a substantially rectangular box-shaped case 41 instead of the case 10 of the first embodiment shown in FIG. 1 . The case 41 has a first case 42 instead of the first case 11 shown in FIG. 1 . The case 41 is formed by assembling the first case 42 with the second case 13 of the first embodiment. The first case 42 is made of, for example, an elastic metal plate, such as iron or aluminum. The first case 42 may also be made of, for example, a highly elastic synthetic resin. In the following description, only the differences from the first embodiment will be described in detail.

[0074] As shown in FIG. 15 , the first case 42 is U-shaped when viewed from the front, with both ends of the U-shape extending outward to the left and right. The first case 42 has an upper surface 42a, a pair of upright surfaces 42b, and a pair of flanges 42c. The upright surfaces 42b and the flanges 42c are provided with the same shape and arrangement as the first case 11 of the first embodiment (see FIG. 1). The lower surfaces of the pair of left and right flanges 42c are at approximately the same height. Each upright surface 42b is provided with a hole-shaped engaging portion 42d that penetrates in the left-right direction. Each flange 42c is provided with a mounting hole 42e that penetrates in the up-down direction. The engaging portion 42d and the mounting hole 42e are provided with the same shape and arrangement as the first case 11 of the first embodiment (see FIG. 1).

[0075] As shown in FIG. 15 , the top surface 42a is formed in the shape of a flat plate extending substantially horizontally. An elastic member 43 is held on the inner surface of the top surface 42a. The elastic member 43 may be, for example, a coil spring, a leaf spring, or the like. The elastic member 43 is made of a material separate from but integral with the first case 42. The elastic member 43 biases the first core 3 downward within the case body 41a. Therefore, the second core 4 is also biased downward by the biasing force of the elastic member 43. The second core 4 also receives the biasing force of the elastic member 43 via the first core 3 and the insulating sheet 5. The biasing force of the elastic member 43 causes the lower surface of the protrusion 4c to adhere tightly to the bottom surface 50a of the housing 50. Therefore, heat generated in the second core 4 can be reliably dissipated to the bottom surface 50a of the housing 50. The first core 3 is pressed down from above by the biasing force of the elastic means 43, so that heat generated in the first core 3 can be reliably dissipated to the second core 4 via the insulating sheet 5. The noise filter 40 described above has the same effects as the noise filter 1 of the first embodiment (see FIG. 1).

[0076] The noise filters of the first to fourth embodiments described above can be modified in various ways. For example, a noise filter installed on an electrical path between a power conversion device and low-voltage output auxiliary equipment in an electric vehicle has been described as an example. However, the noise filters of the present disclosure can be applied to a variety of electrical products. The up / down, front / rear, left / right directions exemplified in this disclosure do not indicate the actual orientations of the product and may be changed as appropriate. For example, even if the bottom surface 50a of the housing 50 faces the ceiling, the first core 3 and the second core 4 can be biased toward the bottom surface 50a by elastic means, thereby allowing the second core 4 to adhere closely to the bottom surface 50a.

[0077] The bus bar 2 is exemplified as the conductive member. However, the conductive member may be, for example, an electric cord. For example, the case material may be made of metal as long as the structure can ensure the insulation of the conductive member. For example, the case material may be made of synthetic resin as long as the elasticity of the elastic means provided in the case can be ensured. The first case and the second case may be made of the same material or different materials.

[0078] In the example shown, the first core 3 and the second core 4 are made of ferrite. Alternatively, the first core 3 and the second core 4 may be made of, for example, permanent magnets made of a material other than ferrite. In the example shown, the insulating sheet 5 is placed between the first core 3 and the second core 4. Alternatively, for example, a thin metal plate may be placed between the first core 3 and the second core 4. A configuration in which no intervening member is placed between the first core 3 and the second core 4 may also be used.

[0079] The first core 3 is U-shaped and the second core 4 is I-shaped. Alternatively, the first core may be I-shaped and the second core may be U-shaped. For example, both the first core and the second core may be U-shaped. For example, the first core may be E-shaped, and separate conductive members may pass through each of the two grooves in the E-shape.

[0080] In the examples shown, the elastic means 12, 23, 32 are integrally formed from the same material as the case. Alternatively, for example, the elastic means may be formed from a material different from the case and assembled integrally. In the examples shown, the elastic means 12, 23, 32 are cantilevered leaf springs. In the example shown, the elastic means 43 is a coil spring. Alternatively, for example, the elastic means may be replaced with a highly elastic rubber member.

[0081] In the illustrated example, the case is fixed to the housing 50 at two locations, such as the male screw 7 and the boss portion 31m. Alternatively, the case may be fixed to the housing 50 at one location, or at three or more locations. The aluminum housing 50 is illustrated as an object to which the noise filter is to be attached. Alternatively, the case may be fixed to another object with good thermal conductivity.

[0082] The hole-shaped engaging portion 11e has been exemplified as the engaging portion of the first case 11. The protrusion-shaped engaging portion 22f has been exemplified as the engaging portion of the first case 22. However, the first case engaging portion that engages with the second case may be, for example, groove-shaped.

Claims

1. A noise filter comprising: a first core made of ferrite; a second core made of ferrite facing the first core; a conductive member that passes between the first core and the second core and has connection terminals at each end; a case that houses the first core and the second core and allows the conductive member to pass through; and elastic means that is provided in the case and can urge the first core toward the second core.

2. A noise filter according to claim 1, wherein the second core has a protrusion that protrudes from the opening of the case and that, when the biasing force of the elastic means is generated, is pushed against the biasing force and moves into the case.

3. A noise filter according to claim 1 or 2, wherein the case has a support piece that protrudes from the case body and has a holding recess formed therein into which the conductive member is inserted.

4. A noise filter according to claim 3, wherein the support piece is provided with a claw that prevents the conductive member from coming off the holding recess.

5. A noise filter according to any one of claims 1 to 4, wherein the case includes a first case that covers the first core and is equipped with the elastic means, and a second case that covers the second core and engages with the first case.

6. A noise filter according to claim 5, wherein the first case is made of a metal plate, and the elastic means utilizes the elastic force of the metal plate.

7. A noise filter according to any one of claims 1 to 6, wherein the first case has flanges that extend out on both sides of the elastic means and have mounting holes formed therein.

8. A noise filter according to claim 7, wherein the first case has an engaging portion that engages with the second case between the elastic means and the flange.

9. A noise filter according to any one of claims 1 to 8, wherein one of the first core and the second core has an opposing surface that is entirely flat and faces the other core, an insulating sheet is placed on the opposing surface, and the other core has a recess formed therein through which the conductive member is passed.

Images