Noise Absorber

Abstract

To provide a highly reliable noise absorber that does not reduce the noise absorption effect of a magnetic core even when the hinge of a split case is damaged or deteriorated.SOLUTION: A noise absorber includes a cylindrical core case 2 composed of a first split case 2A and a second split case 2B holding split cores (split ferrite cores) 3A and 3B includes a hinge piece 6 provided on each first side edge of the first and second split cases 2A and 2B and connecting these split cases 2A and 2B so as to be able to open and close, and a main engagement portion 4 in which each second side edge of the first and second split cases 2A and 2B are connected, and a sub-engagement portion 5 in which the first side edges of the first and second split cases 2A and 2B are connected.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a noise absorbing device for absorbing noise (noise current) flowing in a cable (electric wire) of an electronic device to prevent the electronic device from malfunctioning due to the noise, and more particularly to a noise absorbing device with improved reliability of its noise absorption effect. [Background technology]

[0002] A noise absorber described in Patent Document 1 has been proposed as this type of noise absorbing device. This noise absorber has a pair of ferrite cores (split cores) made by splitting a cylindrical ferrite in half in the axial direction, and a pair of split cases that support the split cores, and is configured to be attached to an electric wire by sandwiching the split cores and the split cases from both sides of a cable connected to an electronic device. In addition, in the noise absorbing device of Patent Document 1, the pair of split cases are connected by a hinge, and by bending the hinge, the two split cases are assembled into a cylindrical container surrounding the electric wire, and the pair of split cores are formed into a cylindrical shape surrounding the electric wire to form a core loop (ferrite loop).

[0003] In this noise absorbing device, the pair of split cases are integrally formed with the hinge by resin molding, and the hinge is formed as thin as possible to allow bending. Therefore, the hinge may be damaged, such as cracked, by the stress applied to it when it is attached to the electric wire. If the hinge is damaged, it becomes difficult to maintain the cylindrical container shape of the pair of split cases, and the mutual adhesion of the pair of split cores that support it is lost. Even if the hinge is not damaged, the mutual adhesion of the pair of split cores may also be lost if the elastic force decreases due to aging. If the mutual adhesion of the pair of split cores is lost, the ferrite loop surrounding the electric wire cannot be secured, and the noise absorbing effect is reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6761355 [Patent Document 2] Patent No. 2775604 [Patent Document 3] JP 2011-71263 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the problem of the deterioration of the noise absorbing effect due to the damage or deterioration of the hinge, the noise absorbing device of Patent Document 1 forms the hinge from a different material. This causes a problem of the molding process becoming complicated. In addition, the noise absorbing device of Patent Document 2 configures a pair of separate cases separately, and connects both the separate cases with a hinge configured with a rotation center shaft and a bearing. Therefore, this noise absorbing device cannot configure the pair of separate cases as one body by resin molding, and the number of parts increases, the structure becomes complicated, and the cost becomes high. In addition, when configuring the noise absorbing device, it is necessary to assemble it using the rotation center shaft, which makes the assembly workability worse.

[0006] Furthermore, the noise absorbing device of Patent Document 3 has connection parts on both sides of the hinge that connects the pair of split cases, and these connection parts relieve the stress applied to the hinge to prevent damage to the hinge. Although it is possible to form the pair of split cases of this noise absorbing device by resin molding, the force required to bend the hinge is inevitably increased by providing the connection parts, which makes it difficult to install the noise absorbing device. In addition, since this connection part is bent in the same way as the hinge, it may crack or deteriorate due to aging, which reduces the support function of the ferrite core by the split cases and reduces the noise absorbing effect.

[0007] An object of the present invention is to provide a highly reliable noise absorbing device in which the noise absorbing effect of the split core is not reduced even if the hinge of the split case is damaged or deteriorated. [Means for solving the problem]

[0008] The present invention is a noise absorbing device that comprises a first split case and a second split case that hold a split core, and that forms a cylindrical core case in which the split core is housed when the first and second split cases are brought together. The device comprises hinge pieces provided on each first side edge of the first and second split cases to connect the first and second split cases so that the first and second split cases can be opened and closed, main engagement portions provided on each second side edge of the first and second split cases to connect the second side edges, and secondary engagement portions provided on each first side edge of the first and second split cases to connect the first side edges.

[0009] The present invention In the present invention, a protruding piece is formed on a first side edge portion of the end wall of one of the first and second separate cases in the axial direction of the cylinder, the protruding piece overlapping with the first side edge portion of the end wall of the other separate case in the axial direction of the cylinder, and the secondary engagement portion includes a first engagement projection formed on an outer surface of the end wall of the other separate case in the axial direction of the cylinder, and a second engagement projection capable of engaging with the first engagement projection and formed on an inner surface of the protruding piece in the axial direction of the cylinder. It is considered to be composed.

[0010] In the present invention, the auxiliary engagement portions are disposed on the end walls of both ends of the first and second separate cases in the axial direction. do. Effect of the Invention

[0011] According to the present invention, even if the flexibility of the hinge piece is reduced or the hinge piece is damaged, the secondary engagement portion maintains the connected state of the first side edge portions of the first and second split cases, so that the container shape of the core case is maintained and the core loop created by the split core is secured, thereby maintaining the noise absorption effect. [Brief description of the drawings]

[0012] [Figure 1] 1 is an external perspective view of a noise absorbing device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of the noise absorbing device of the first embodiment with a core case open. [Diagram 3] 1A is a front view, and FIG. 1B is a left side view of a noise absorbing device according to a first embodiment. [Figure 4] 4A and 4B are cross-sectional views taken along line aa of the noise absorbing device of the first embodiment, and FIG. 4B is an enlarged cross-sectional view taken along line b1-b1 of FIG. [Diagram 5] FIG. 11 is a perspective view of a noise absorbing device according to a second embodiment with a core case open. [Figure 6] 10A is an external perspective view of a noise absorbing device according to a second embodiment, and FIG. 10B is an enlarged partial cross-sectional view taken along line b2-b2 thereof. [Figure 7] FIG. 11 is a perspective view of a noise absorbing device according to a third embodiment with a core case opened. [Figure 8] 11A is an external perspective view of a noise absorbing device according to a third embodiment, and FIG. 11B is an enlarged partial cross-sectional view taken along line b3-b3 thereof. [Figure 9] FIG. 11 is a perspective view of a noise absorbing device according to a fourth embodiment with a core case opened. [Figure 10] 4A is an external perspective view of a noise absorbing device according to a fourth embodiment, and FIG. 4B is an enlarged partial cross-sectional view taken along line b4-b4 thereof. [Figure 11] FIG. 13 is a perspective view of a noise absorbing device according to a fifth embodiment with a core case opened. [Figure 12] 13A and 13B are external perspective views of a noise absorbing device according to a fifth embodiment, as viewed from different directions. [Figure 13] An enlarged cross-sectional view taken along line b5-b5 in Figure 12(b). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Embodiment 1) Next, a first embodiment of the present invention will be described. Fig. 1 is an external perspective view of a noise absorbing device 1 of the first embodiment attached to a cable C shown in phantom lines. A core case 2 that can be opened and closed and is assembled into a cylindrical shape when closed is formed by resin molding, and a ferrite core 3 is installed inside. In the noise absorbing device, the cable C is inserted into a cable insertion hole provided in the center of the core case 2, and the ferrite core 3 absorbs noise in the current flowing through the cable C.

[0014] FIG. 2 is a perspective view of the core case 2 in an open state. The core case 2 includes a pair of split cases 2A and 2B in the shape of a semi-cylindrical container. The split case 2A on the left side in FIG. 2 is called the first split case, and the split case 2B on the right side is called the second split case. Each split case 2A and 2B is composed of a pair of semi-annular end walls 21 facing each other at a required distance in the axial direction, and a semi-cylindrical peripheral wall 22 sandwiched between the end walls 21 and extending along the periphery of both end walls 21. A ferrite core 3 is installed inside the core case 2. The ferrite core 3 is configured as a pair of split cores 3A and 3B in the shape of a semi-cylindrical container obtained by dividing a cylindrical ferrite core into two in the radial direction, and is installed and supported by the first and second split cases 2A and 2B, respectively.

[0015] Although not shown in the figure, each of the split cores 3A, 3B is supported by a support structure provided in each of the split cases 2A, 2B in a state where it is prevented from falling out of the respective split cases 2A, 2B. In addition, as shown only for the split case 2A in Fig. 1, a core pressing piece 24 is formed on the peripheral wall 22 of the split cases 2A, 2B, in which an area sandwiched between a pair of axially opposed slits 23 exerts an elastic force radially inwardly, and the elastic force of this core pressing piece 24 brings the pair of split cores 3A, 3B into close contact with each other inside the core case 2, forming a ferrite loop around the cable C.

[0016] The first and second separate cases 2A, 2B are connected to each other by a flexible hinge piece 6 made of a thin piece at opposing portions of the peripheral walls 22, i.e., the right side edge of the first separate case 2A and the left side edge of the second separate case 2B in Figure 2 (hereinafter referred to as the first side edge). The flexibility of the hinge piece 6 allows the other side edge of each of the two separate cases 2A, 2B to rotate about the hinge piece 6 (hereinafter referred to as the second side edge), and this rotation allows the two separate cases 2A, 2B to be opened and closed.

[0017] FIG. 3(a) is a front view of the noise absorbing device, and FIG. 3(b) is a left side view thereof. FIG. 4(a) is a cross-sectional view taken along line aa in FIG. 3(b), and FIG. 4(b) is an enlarged cross-sectional view taken along line b1-b1 in FIG. 3(a). An engagement protrusion 40 protruding from the peripheral surface of the peripheral wall 22 is provided on the second side edge of the first separate case 2A, and a frame-shaped engagement piece 41 having an engagement hole that engages with the engagement protrusion 40 is provided on the second side edge of the second separate case 2B. As a result, when both separate cases 2A and 2B are rotated to the closed state with the hinge piece 6 as a fulcrum, the engagement hole of the engagement piece 41 is engaged with the engagement protrusion 40, and both separate cases 2A and 2B are assembled into a cylindrical container. These engagement protrusions 40 and engagement pieces 41 are configured as the main engagement portion 4 of the present invention.

[0018] The end walls 21 of both sides of the first and second separate cases 2A and 2B are integrally formed with protruding pieces 25, 26 whose edges protrude in an arc shape by a required dimension at positions corresponding to the first and second side edges, respectively. Of these protruding pieces 25, 26, the protruding piece 25 of the first separate case 2A is formed in a state in which it is displaced by a required dimension inward in the plate thickness direction from the outer surface of the end wall 21. Due to this displacement, a recess 21a is formed in the outer surface of the end wall 21 in the thickness direction. On the other hand, the protruding piece 26 of the second separate case 2B is formed in a position along the outer surface of the end wall 21. Therefore, the protruding pieces 25, 26 of the first and second separate cases 2A, 2B are positioned at different positions in the axial direction of the cylinder, and the protruding piece 25 of the first separate case 2A is positioned further inward in the axial direction than the protruding piece 26 of the second separate case 2B, and when both separate cases 2A, 2B are closed, the protruding piece 26 of the second separate case 2B is positioned to enter along the recess 21a of the first separate case 2A.

[0019] The protruding piece 26 on the first side edge side of the second separate case 2B has an engagement hole 51 penetrating in the plate thickness direction, i.e., in the axial direction, at a required position. Here, the circular engagement hole 51 is opened. Meanwhile, a circular hook-shaped engagement protrusion 50 protruding in the axial direction is provided in the recess 21a formed on the outer surface of the first side edge side of the end wall 21 of the first separate case 2A. The engagement protrusion 50 is formed as a tapered (triangular) engagement protrusion 50 whose protrusion height gradually increases, and can be engaged with the engagement hole 51. When these are engaged, the protruding piece 26 of the second separate case 2B and the end wall 21 of the first separate case 2A can be connected to each other, and the engagement protrusion 50 and the engagement hole 51 are configured as the secondary engagement portion 5 in the present invention.

[0020] 1 and 2, the noise absorbing device of the first embodiment has a pair of bag-shaped fitting grooves 27 formed on the outer surface of one end wall 21 of the first separate case 2A, the pair opening toward the peripheral wall, and a fastener (not shown) used for fixing and supporting the noise absorbing device 1 to a chassis or the like is fitted into the fitting grooves 27. This fastener is not very relevant to the present invention, so a detailed description thereof will be omitted. Also, a band insertion portion 28 protruding in the axial direction is provided on the outer surface of the end wall 21 of the second separate case 2B, and a band (not shown) for fixing the noise absorbing device 1 to the cable C is inserted into the fitting grooves 27. This band is also not very relevant to the present invention, so a detailed description thereof will be omitted.

[0021] In the noise absorbing device 1 having the above configuration, the split cores 3A and 3B are mounted and supported in the first separate case 2A and the second separate case 2B, respectively, as shown in Fig. 2, and then the first separate case 2A and the second separate case 2B are closed so as to sandwich the cable C, and assembled into a cylindrical container-shaped core case 2. At this time, the hinge piece 6 is bent, and for example, the second separate case 2B is rotated counterclockwise in Fig. 2 relative to the first separate case 2A. Then, the two separate cases 2A and 2B are closed to face each other, and the engagement protrusion 40 is engaged with the engagement hole of the engagement piece 41. As a result, the second side edges of the two separate cases 2A and 2B are connected by the main engagement part 4, and the two separate cases 2A and 2B are assembled into a cylindrical container shape around the cable C, as shown in Fig. 1.

[0022] In this state, as shown in Fig. 4(a), the opposing surfaces of the split cores 3A, 3B housed in the split cases 2A, 2B are in close contact with each other to form a cylindrical shape, and a ferrite loop is formed surrounding the cable C. At this time, as the split cases 2A, 2B are closed, the protruding pieces 25, 26 are overlapped with each other, so that the arc-shaped edges of the protruding pieces 25, 26 come into contact with the cable C, preventing the cable C from being pinched between the split cores 3A, 3B that are in close contact with each other. This is as described in the applicant's Patent No. 6472977, and detailed description will be omitted.

[0023] When the core case 2 is assembled with the first and second separate cases 2A and 2B, the protruding piece 26 of the second separate case 2B, which has been rotated around the hinge piece 6 as a fulcrum, is positioned in the recess 21a of the first separate case 2A. When this protruding piece 26 is positioned in the recess 21a of the first separate case 2A, the secondary engagement portion 5 engages with the protruding piece 26. That is, as shown in FIG. 4(b), the engagement protrusion 50 of the first separate case 2A engages with the engagement hole 51 of the protruding piece 26 of the second separate case 2B. This engagement is performed at both ends of the first side edge of each separate case 2A and 2B in the axial direction. As a result, the first side edge of each separate case 2A and 2B is connected to each other in the axial direction of the cylinder, and this connection restricts the relative movement of the first side edge of each separate case 2A and the second separate case 2B, i.e., the side edge where the hinge piece 6 is provided, in the circumferential direction.

[0024] In the noise absorbing device 1 assembled in this manner, when the flexibility of the hinge piece 6 is reduced due to aging, or when the hinge piece 6 is damaged by an external force or internal stress, the connection state of the two separate cases 2A, 2B at the first side edge is deteriorated or damaged. Therefore, even if the connection state of the first separate case 2A and the second separate case 2B is maintained by the main engagement portion 4 at the second side edge, the first separate case 2A and the second separate case 2B are relatively moved or displaced in a direction in which they move away from each other at the first side edge. Therefore, the mutual adhesion of the pair of split cores 3A, 3B supported in the core case 2 is not maintained, a ferrite loop surrounding the cable C is not formed, and the noise absorbing effect is reduced.

[0025] In this embodiment 1, the secondary engagement portion 5 engages the first side edge of the first and second separate cases 2A, 2B, thereby maintaining the connection state at the first side edge of both separate cases 2A, 2B, i.e., the connection state at the side edge where the hinge piece 6 is present. This prevents relative movement or displacement between the first and second separate cases 2A, 2B due to deterioration or damage to the hinge piece 6, maintaining the cylindrical container shape of the core case 2 and maintaining the noise absorbing effect. In particular, the secondary engagement portion 5 engages on both sides of the core case 2 in the axial direction, which enhances the effect of maintaining the cylindrical container shape.

[0026] When disassembling the noise absorbing device 1, an appropriate jig or tool can be used to elastically deform the protruding piece 26 of the second separate case 2A toward the outer surface in the axial direction, thereby releasing the engagement between the engagement protrusion 50 and the engagement hole 51 and releasing the connected state at the secondary engagement portion 5. Therefore, similar to a conventional core case, by releasing the engagement at the primary engagement portion 4, the first and second separate cases 2A, 2B can be returned to the open state, making them reusable.

[0027] (Embodiment 2) FIG. 5 is a perspective view of the noise absorbing device 1A of the second embodiment in an open state, FIG. 6(a) is a perspective view of the device in an assembled state, and FIG. 6(b) is an enlarged partial cross-sectional view taken along the line b2-b2 in FIG. 6(a). The second embodiment corresponds to a modified example of the first embodiment, and the parts equivalent to those of the first embodiment are given the same reference numerals and will not be described. In the second embodiment, the basic structure of each of the first and second separate cases 2A and 2B is the same as that of the first embodiment. Also, each of the separate cases 2A and 2B is provided with a protruding piece 25, 26, respectively, and the auxiliary engagement portion 5 is also provided for the protruding piece 26 of the second separate case 2B. Meanwhile, in the second embodiment, as the configuration of the auxiliary engagement portion 5, the protruding piece 26 of the second separate case 2B has a hook-shaped second engagement protrusion 53 formed on the inner surface thereof, and the recess 21a provided in the end wall 21 of the first separate case 2A has a hook-shaped first engagement protrusion 52 formed on the outer surface thereof.

[0028] In the noise absorbing device 1A of the second embodiment, the hinge piece 6 connecting the first side edges of the two separate cases 2A and 2B is bent, and the second side edges of the two separate cases 2A and 2B are connected by the main engagement portion 4 to assemble the core case 2. At this time, the protruding piece 26 of the second separate case 2B enters the recess 21a of the end wall 21 of the first separate case 2A, so that the first engagement protrusion 52 of the first separate case and the second engagement protrusion 53 of the second separate case 2B are engaged with each other in the direction around the cylindrical axis. As a result, the protruding piece 26 of the second separate case 2B and the end wall 21 of the first separate case 2A are connected in the circumferential direction around the cylindrical axis, and this connection restricts the relative movement in the circumferential direction of the first side edges of the first separate case 2A and the second separate case 2B, i.e., the side edges where the hinge piece 6 is provided. Although details are omitted, at this time, the first engagement projection 52 and the second engagement projection 53 are inserted into recesses provided on the other projection, so that the positions of the protruding piece 26 and the end wall 21 in the axial direction of the cylinder are maintained.

[0029] As a result, similarly to the first embodiment, even if the hinge piece 6 is deteriorated or broken when the noise absorbing device 1A is in an assembled state, the engagement at the secondary engagement portion 5 prevents relative movement or displacement at the first side edge portion of the first separate case 2A and the second separate case 2B, and maintains the cylindrical container shape of the core case 2. Therefore, the mutual adhesion of the pair of internally mounted split cores 3A, 3B is maintained, a ferrite loop surrounding the cable is secured, and the noise absorbing effect is maintained.

[0030] In the second embodiment, since there is no engagement hole 51 in the protruding piece 26 as in the first embodiment, there is no need for a slider or the like for forming the engagement hole 51 when resin molding the core case 2, and this has the advantage of simplifying the mold structure for molding. In addition, since the engagement hole 51 and the engagement protrusion 50 are not exposed to the outside as in the first embodiment, the appearance can be improved.

[0031] (Embodiment 3) Fig. 7 is a perspective view of the noise absorbing device 1B of the third embodiment in an open state, Fig. 8(a) is a perspective view of the device in an assembled state, and Fig. 8(b) is an enlarged partial cross-sectional view taken along line b3-b3 in Fig. 8(a). Parts equivalent to those of the first embodiment are given the same reference numerals and will not be described. In the third embodiment, the core case 2 is made up of a first separate case 2A and a second separate case 2B, and this core case 2 is formed to have a longer dimension in the axial direction than the core cases of the first and second embodiments. Therefore, the pair of separate cores 3A and 3B are also formed to have a corresponding dimension in the axial direction.

[0032] As the dimension in the axial direction is lengthened in this manner, the hinge pieces 6 connecting the first side edge portions of the first and second separate cases 2A and 2B are provided at two locations spaced apart in the axial direction, and the reliability of the hinge pieces 6, such as durability, is improved by dispersing the stress applied to the hinge pieces 6 by the pair of hinge pieces 6. The main engagement portion 4 is also provided at two locations in the axial direction. That is, a pair of engagement protrusions 40 is provided at the second side edge portion of the first separate case 2A, and a pair of engagement pieces 41 is provided at the second side edge portion of the second separate case 2B, and the engagement protrusions 40 engage with the engagement holes provided in these engagement pieces 41 to form the main engagement portion 4. This improves the reliability of the connection strength at the second side edge portions of the first and second separate cases 2A and 2B.

[0033] In the core case 2 of the third embodiment, a narrow groove 21b is formed in the outer surface of the end wall 21 at both ends of the first separate case 2A at a position along the first side edge, and a hook-shaped engagement protrusion 54 is formed on the inner bottom surface of the groove 21b, i.e., the outer surface of the end wall 21, protruding outward in the axial direction. The groove 21b is used to allow the die to escape when the engagement protrusion 54 is molded.

[0034] On the other hand, the end walls 21 at both ends of the second separate case 2B are formed with engagement pieces 55 that protrude by a required dimension. These engagement pieces 55 are formed in the shape of plate pieces of a required width dimension in the region on the first side edge side of the second separate case 2B, and engagement holes 55a that penetrate in the plate thickness direction are opened at the tip side of the protruding direction. In addition, a recessed groove 21c that connects to the engagement hole 55a is formed on the outer surface of the end wall 21, and this is for allowing the die to escape when the engagement hole 55a is molded. The secondary engagement portion 5 is composed of these engagement projections 54 and engagement pieces 55 (engagement holes 55a).

[0035] In the core case 2 of the third embodiment, a pair of cable clamping pieces 29 are provided at both ends in the axial direction of the first separate case 2A, and these cable clamping pieces 29 regulate the cable to the axial position of the core case 2. The cable clamping pieces 29 are as described in the applicant's Japanese Patent No. 5526007, and therefore a detailed description thereof will be omitted.

[0036] In the noise absorbing device 1B of the third embodiment, the hinge piece 6 is bent and the second side edge portions of both the split cases 2A and 2B are connected by a pair of main engagement portions 4 to assemble the core case 2 with the first and second split cases 2A and 2B. In the assembled state, the engagement piece 55 of the second split case 2B is inserted into the recessed groove 21b of the first split case 2A, and at the same time, the engagement hole 55a is engaged with the engagement protrusion 54. As a result, the first side edge portions of both the first and second split cases 2A and 2B are connected by the sub-engagement portion 5 at both ends in the axial direction. That is, at both ends of the core case 2, the engagement hole 55a of the engagement piece 55 of the second split case 2B is engaged with the engagement protrusion 54 of the first split case 2A, and the first side edge portions of the first and second split cases 2A and 2B are connected to each other, so that the relative movement is restricted at both ends in the axial direction.

[0037] This prevents relative movement or displacement even if the hinge piece 6 is damaged or if the first side edges of the first and second separate cases 2A, 2B move apart due to a decrease in flexibility caused by aging, as in the first embodiment. This maintains the cylindrical container shape of the core case 2, maintains the mutual adhesion of the pair of internally supported split cores 3A, 3B, and ensures the ferrite loop, thereby maintaining the noise absorption effect.

[0038] (Embodiment 4) Fig. 9 is a perspective view of the noise absorbing device 1C of the fourth embodiment in an open state, Fig. 10(a) is a perspective view of the device in an assembled state, and Fig. 10(b) is an enlarged partial cross-sectional view taken along line b4-b4 in Fig. 10(a). The fourth embodiment corresponds to a modified example of the third embodiment, and the same reference numerals are used for equivalent parts to the third embodiment, and the description thereof will be omitted. In particular, as the dimension of the core case 2 in the axial direction is lengthened, the hinge pieces 6 are provided at two positions spaced apart in the axial direction, and the main engagement parts 4 are also provided at two positions in the axial direction.

[0039] In the fourth embodiment, the second separate case 2B has a hook-shaped second engagement protrusion 57 formed on the outer surface facing the recessed groove 21c, instead of the engagement piece 54 and engagement hole 55a of the third embodiment. On the other hand, the first separate case 2A has a recess 21d formed on the inner surface side of the end wall 21, and is configured so that the engagement protrusion 57 of the second separate case 2B enters this recess 21d when the core case 2 is closed. In addition, a hook-shaped first engagement protrusion 56 is formed on the inner surface of the recess 21d, and is capable of engaging with the second engagement protrusion 57. The first engagement protrusion 56 and the second engagement protrusion 57 form the sub-engagement portion 5.

[0040] In the noise absorbing device 1C of the fourth embodiment, the pair of hinge pieces 6 connecting the first side edges of the two separate cases 2A and 2B are bent, and the second side edges of the two separate cases 2A and 2B are connected by the main engagement portion 4 to assemble the core case 2. At this time, the second engagement protrusion 57 of the second separate case 2B enters the recess 21d on the inside of the end wall 21 of the first separate case, and the entered second engagement protrusion 57 and the first engagement protrusion 56 in the recess 21d are engaged with each other. That is, the first side edges of the first separate case 2A and the second separate case 2B are connected to each other by the sub-engagement portion 5. Therefore, the relative movement of the first side edges of the first and second separate cases 2A and 2B is restricted at both ends in the axial direction.

[0041] As a result, even if at least one of the pair of hinge pieces 6 is damaged, or even if the flexibility decreases due to aging and the first side edges of the first and second separate cases 2A, 2B move or displace in the direction separating them, relative movement or displacement of the first and second separate cases 2A, 2B is prevented, and the cylindrical container shape of the core case 2 is maintained. As a result, the mutual adhesion of the pair of internally supported split cores 3A, 3B is maintained, a ferrite loop surrounding the electric wire is secured, and the noise absorption effect is maintained.

[0042] (Embodiment 5) FIG. 11 is a perspective view of the noise absorbing device 1D of the fifth embodiment in an open state, and FIG. 12(a) and FIG. 12(b) are perspective views of the assembled state seen from different directions. FIG. 13 is an enlarged cross-sectional view of the b5-b5 line of FIG. 12(a). In the fifth embodiment, parts equivalent to those in the fourth embodiment are given the same reference numerals and will not be described. In the fifth embodiment, the hinge pieces 6 connecting the first and second separate cases 2A and 2B are composed of a pair of hinge pieces 6 spaced apart in the axial direction as in the fourth embodiment, and the reliability of the hinge pieces 6, such as durability, is improved. Also, the main engagement portions 4 are provided at two locations in the axial direction as in the fourth embodiment.

[0043] On the other hand, the auxiliary engagement portion 5 in the fifth embodiment is disposed at a central position in the axial direction between the pair of hinge pieces 6. That is, an engagement protrusion 58 is formed in a protruding state on the first side edge of the first separate case 2A at a central position in the axial direction between the pair of hinge pieces 6. Also, an engagement piece 59 having an engagement hole 59a that can engage with the engagement protrusion 58 is formed in a protruding state on the first side edge of the second separate case 2B. The engagement protrusion 58 and the engagement piece 59 (engagement hole 59a) constitute the auxiliary engagement portion 5.

[0044] In the noise absorbing device 1D of the fifth embodiment, when the hinge piece 6 connecting the first side edge portions of the two separate cases 2A and 2B is bent and the second side edge portions of the two separate cases 2A and 2B are connected by the main engagement portion 4 to assemble the core case 2 with the first and second separate cases 2A and 2B, the engagement protrusion 58 of the first separate case 2A is engaged with the engagement hole 59a of the engagement piece 59 of the second separate case 2B. That is, the secondary engagement portion 5 is in an engaged state, and the first side edge portions of the first separate case 2A and the second separate case 2B are connected to each other. Therefore, the relative movement of the first and second separate cases 2A and 2B is restricted at approximately the center position in the cylindrical axis direction.

[0045] As a result, even if one or both of the pair of hinge pieces 6 are damaged, or if flexibility decreases due to deterioration over time and the first side edges of the first and second split cases 2A, 2B move or displace in a direction separating them, relative movement or displacement between the first and second split cases 2A, 2B is prevented, the cylindrical container shape of the core case 2 is maintained, the mutual adhesion of the pair of split cores 3A, 3B is maintained, a ferrite loop surrounding the electric wire is secured, and the noise absorption effect is maintained.

[0046] In the fifth embodiment, the sub-engagement portion 5 is provided at only one location, at a central position in the axial direction of the core case 2, and therefore the configuration of the sub-engagement portion 5 can be simplified. On the other hand, since the sub-engagement portion 5 is provided at only one location, it is considered that the connecting force between the first and second separate cases 2A, 2B is relatively lower than in the configurations of the first to fourth embodiments in which the sub-engagement portions are provided at both ends in the axial direction. However, since the dimension in the axial direction where the engaging projection 58 and the engaging hole 59a engage can be designed to be larger than in the first to fourth embodiments, the overall connecting force can be made approximately the same as in the first to fourth embodiments.

[0047] In the above-described first to fifth embodiments, various modifications are possible, particularly with respect to the engagement holes and engagement protrusions constituting the secondary engagement portion. For example, the engagement pieces and engagement holes in the first, third and fifth embodiments may be provided in the first separate case, and the engagement protrusions in the second separate case. Also, in the fifth embodiment, the engagement protrusions may be provided in both the first and second separate cases. [Explanation of symbols]

[0048] 1,1A~1D Noise absorber 2 Core Case 2A First Separate Case 2B Second separate case 3 Ferrite core 3A, 3B split core 4 Main engagement part 5 Secondary engagement part 6 Hinge piece

Claims

1. A noise absorbing device comprising a first separate case and a second separate case for holding a split core, the first separate case and the second separate case being fitted together to form a cylindrical core case in which the split core is housed, the noise absorbing device comprising: hinge pieces provided on first side edges of the first and second separate cases for connecting the first and second separate cases so as to be able to open and close; main engagement portions provided on second side edges of the first and second separate cases for connecting the second side edges; and a hinge member provided on the first side edges of the first and second separate cases for connecting the second side edges. a secondary engagement portion that connects the first side edge portions to each other, and a protrusion portion is formed on the first side edge portion of the end wall of one of the end walls in the axial direction of the first and second separate cases, the protrusion portion comprising a first engagement projection formed on the outer surface in the axial direction of the end wall of the other separate case, and a second engagement projection capable of engaging with the first engagement projection and formed on the inner surface in the axial direction of the protrusion.

2. 2. The noise absorbing device according to claim 1, wherein the main engagement portion comprises an engagement protrusion provided on a second side edge portion of one of the first and second split cases, and an engagement piece provided on the second side edge portion of the other of the first and second split cases and having an engagement hole that engages with the engagement protrusion.

3. 3. The noise absorbing device according to claim 1, wherein the auxiliary engagement portions are disposed on end walls of both sides in the axial direction of the first and second separate cases.

4. A noise absorbing device as described in Claim 3, wherein the protruding piece cooperates with a protruding piece formed on a first side edge portion of the end wall of the other split case to prevent a cable inserted into the core case from being pinched between the one and the other split cases.

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