JP7629191B2 - Noise Absorber - Google Patents

Description

The present invention relates to a noise absorbing device that absorbs noise (noise current) flowing through the cables (electric wires) of electronic devices to prevent malfunction of the electronic devices due to the noise, and in particular to a noise absorbing device that has improved reliability of its noise absorption effect.

The 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 cylindrical ferrite in half in the axial direction, and a pair of split cases that support each of the split cores. The cable connected to an electronic device is attached to the electric wire by sandwiching the split cores between the split cases from both sides. 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 that surrounds the electric wire, and the pair of split cores are formed into a cylindrical shape that surrounds the electric wire to form a core loop (ferrite loop).

In this noise absorbing device, the pair of split cases are formed integrally with the hinge by resin molding, and the hinge is formed as thin as possible to allow bending. As a result, the stress applied to the hinge when attaching it to the electric wire may cause damage such as cracking the hinge. 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 deterioration over time. 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 absorption effect is reduced.

Patent No. 6761355 Patent No. 2775604 JP 2011-71263 A

To solve this problem of reduced noise absorption effectiveness due to damage or deterioration of the hinges, the noise absorbing device of Patent Document 1 forms the hinges from a different material. This poses the problem of a complicated molding process. In addition, the noise absorbing device of Patent Document 2 constructs a pair of separate split cases, which are connected by a hinge consisting of a rotation center shaft and a bearing. As a result, this noise absorbing device cannot construct the pair of split cases as a single unit by resin molding, which increases the number of parts and complicates the structure, resulting in higher costs. In addition, when constructing the noise absorbing device, it is necessary to assemble it using the rotation center shaft, which reduces assembly workability.

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 construct this noise absorbing device by molding the pair of split cases with resin, the provision of the connection parts inevitably increases the force required to bend the hinge, making it difficult to install the noise absorbing device. Furthermore, 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 provided by the split cases and reduces the noise absorbing effect.

The 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.

The present invention is a noise absorbing device that includes a first split case and a second split case that hold a split core, and that forms a cylindrical core case that houses the split core when the first and second split cases are mated together. The device includes hinge pieces that are provided on the first side edges of the first and second split cases and connect the first and second split cases so that they can be opened and closed, main engagement parts that are provided on the second side edges of the first and second split cases and connect the second side edges, and secondary engagement parts that are provided on the first side edges of the first and second split cases and connect the first side edges.

In the present invention, of the end walls in the axial direction of the first and second separate cases, a protruding piece is formed on a first side edge portion of the end wall of one of the separate cases which overlaps in the axial direction with the first side edge portion of the end wall of the other separate case, and the secondary engagement portion is configured to include 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 protruding piece .

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

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 connection state of the first side edges of the first and second split cases, so the container shape of the core case is maintained, the core loop of the split core is secured, and the noise absorbing effect is maintained.

1 is an external perspective view of a noise absorbing device according to a first embodiment of the present invention. FIG. 2 is a perspective view of the noise absorbing device according to the first embodiment with a core case open. 1A is a front view, and FIG. 1B is a left side view of a noise absorbing device according to a first embodiment. 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. FIG. 11 is a perspective view of a noise absorbing device according to a second embodiment with a core case open. 11A is an external perspective view of a noise absorbing device according to a second embodiment, and FIG. 11B is an enlarged partial cross-sectional view taken along line b2-b2 thereof. FIG. 11 is a perspective view of a noise absorbing device according to a third embodiment with a core case opened. 3A is an external perspective view of a noise absorbing device according to a third embodiment, and FIG. 3B is an enlarged partial cross-sectional view taken along line b3-b3 thereof. FIG. 11 is a perspective view of a noise absorbing device according to a fourth embodiment with a core case open. 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. FIG. 13 is a perspective view of a noise absorbing device according to a fifth embodiment with a core case opened. 13A and 13B are external perspective views of a noise absorbing device according to a fifth embodiment, as viewed from different directions. An enlarged cross-sectional view taken along line b5-b5 in FIG.

(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.

Figure 2 is a perspective view of the core case 2 in an open state. The core case 2 has 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 Figure 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. The core case 2 also has a ferrite core 3 installed inside. The ferrite core 3 is configured as a pair of split cores 3A and 3B in the shape of a semi-cylindrical cylinder, which are formed by dividing a cylindrical ferrite core into two in the radial direction, and is supported inside the first and second split cases 2A and 2B, respectively.

Although not shown in the figure, each split core 3A, 3B is supported by a support structure provided in each split case 2A, 2B in a state that prevents it from falling out of the split case 2A, 2B. In addition, as shown only for split case 2A in Figure 1, the peripheral wall 22 of split cases 2A, 2B is formed with a core pressing piece 24 that exerts an elastic force radially inward in the area sandwiched between a pair of axially opposed slits 23, 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.

The first and second separate cases 2A and 2B are connected to each other by a flexible hinge piece 6 made of a thin piece at the opposing portions of the peripheral wall 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 FIG. 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 and 2B to rotate around the hinge piece 6 (hereinafter referred to as the second side edge), and this rotation opens and closes the two separate cases 2A and B.

Figure 3(a) is a front view of the noise absorbing device, and Figure 3(b) is its left side view. Also, Figure 4(a) is a cross-sectional view taken along line a-a in Figure 3(b), and Figure 4(b) is an enlarged cross-sectional view taken along line b1-b1 in Figure 3(a). The first separate case 2A has an engagement protrusion 40 protruding from the peripheral surface of the peripheral wall 22 at its second side edge, and the second separate case 2B has a frame-shaped engagement piece 41 having an engagement hole that engages with the engagement protrusion 40 at its second side edge. As a result, when the two separate cases 2A and 2B rotate to the closed state with the hinge piece 6 as a fulcrum, the engagement hole of the engagement piece 41 engages with the engagement protrusion 40, and the two 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.

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 of 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 inward in the plate thickness direction by a required dimension from the outer surface of the end wall 21. Due to this displacement, a recess 21a in the thickness direction is formed on the outer surface of the end wall 21. 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, and the protruding piece 25 of the first separate case 2A is positioned inside the protruding piece 26 of the second separate case 2B in the axial direction, 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.

The protruding piece 26 on the first side edge side of the second separate case 2B has an engagement hole 51 that penetrates in the plate thickness direction, i.e., in the axial direction, at a required position. Here, a circular engagement hole 51 is opened. On the other hand, a circular hook-shaped engagement protrusion 50 that protrudes in the axial direction is protruding from 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. This 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 these engagement protrusions 50 and engagement holes 51 are configured as the secondary engagement portion 5 in this invention.

As shown in Figs. 1 and 2, the noise absorbing device of embodiment 1 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, which open toward the peripheral wall. A fastener (not shown) is used to fix and support the noise absorbing device 1 to a chassis or the like and is fitted into the fitting grooves 27. This fastener is not relevant to the present invention and therefore will not be described in detail. In addition, 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, which is designed to allow a band (not shown) to be inserted for fixing the noise absorbing device 1 to the cable C. This band is also not relevant to the present invention and therefore will not be described in detail.

In the noise absorbing device 1 having the above configuration, the split cores 3A and 3B are mounted and supported in the first and second split cases 2A and 2B, respectively, as shown in FIG. 2, and then the first and second split cases 2A and 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 pieces 6 are bent, and for example, the second split case 2B is rotated counterclockwise in FIG. 2 relative to the first split case 2A. Then, the two split 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 split cases 2A and 2B are connected by the main engagement parts 4, and as shown in FIG. 1, the two split cases 2A and 2B are assembled into a cylindrical container around the cable C.

In this state, as shown in FIG. 4(a), the opposing surfaces of the split cores 3A, 3B housed inside the split cases 2A, 2B are in close contact with each other to form a cylindrical shape, forming a ferrite loop that surrounds 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, so a detailed explanation will be omitted.

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 is 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 and the engagement hole 51 of the protruding piece 26 of the second separate case 2B are engaged. 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, both separate cases 2A and 2B are connected to each other at the first side edge in the direction around the axial direction, and this connection restricts the relative movement in the circumferential direction of the first side edge of the first separate case 2A and the second separate case 2B, i.e., the side edge where the hinge piece 6 is provided.

When the bending property of the hinge piece 6 of the noise absorbing device 1 assembled in this manner 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 split cases 2A, 2B at the first side edge is deteriorated or damaged. Therefore, even if the first split case 2A and the second split case 2B are maintained in a connected state by the main engagement portion 4 at the second side edge, the first split case 2A and the second split 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 no longer maintained, the ferrite loop surrounding the cable C is not formed, and the noise absorbing effect is reduced.

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, enhancing the effect of maintaining the cylindrical container shape.

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 connection at the secondary engagement portion 5. Therefore, just like a conventional core case, releasing the engagement at the primary engagement portion 4 allows the first and second separate cases 2A and 2B to return to the open state, making them reusable.

(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 modification 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 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.

In the noise absorbing device 1A of the second embodiment, 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. 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 cylinder 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 cylinder axis, and this connection restricts the relative movement of the first side edge portions of the first separate case 2A and the second separate case 2B, i.e., the side edge portions where the hinge piece 6 is provided, in the circumferential direction. Although details are omitted, at this time the first engagement protrusion 52 and the second engagement protrusion 53 are inserted into recesses provided on the other side, so the axial position of the protruding piece 26 and the end wall 21 is maintained.

As a result, as in the first embodiment, even if the hinge piece 6 deteriorates or breaks when the noise absorbing device 1A is assembled, the engagement at the secondary engagement portion 5 prevents relative movement or displacement at the first side edge of the first separate case 2A and the second separate case 2B, and the cylindrical container shape of the core case 2 is maintained. 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.

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 engagement protrusion 50 are not exposed to the outside as in the first embodiment, the external appearance can be improved.

(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 split cores 3A and 3B are also formed to have a corresponding dimension in the axial direction.

As a result of the increased length in the axial direction, the hinge pieces 6 connecting the first side edges of the first and second separate cases 2A and 2B are provided at two locations spaced apart in the axial direction, and the stress applied to the hinge pieces 6 is dispersed by the pair of hinge pieces 6, thereby improving the reliability of the hinge pieces 6, such as their durability. The main engagement portion 4 is also provided at two locations in the axial direction. That is, a pair of engagement protrusions 40 are provided at the second side edge of the first separate case 2A, and a pair of engagement pieces 41 are provided at the second side edge 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 edges of the first and second separate cases 2A and 2B.

In the core case 2 of the third embodiment, a narrow groove 21b is formed in the outer surface of the end walls 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.

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 the required dimension. These engagement pieces 55 are formed as plate pieces of the required width dimension in the region on the first side edge side of the second separate case 2B, and an engagement hole 55a that penetrates in the plate thickness direction is 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 molding the engagement hole 55a. The secondary engagement portion 5 is composed of these engagement projections 54 and engagement pieces 55 (engagement hole 55a).

The core case 2 of the third embodiment has a pair of cable clamping pieces 29 erected at both ends of the first separate case 2A in the axial direction, and these cable clamping pieces 29 are configured to restrict the cable to the axial position of the core case 2. The cable clamping pieces 29 are as described in the applicant's Patent No. 5,526,007, so a detailed description will be omitted.

In the noise absorbing device 1B of the third embodiment, the hinge piece 6 is bent and the second side edge portions of the two 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 the first and second split cases 2A and 2B are connected by the secondary 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 at both ends in the axial direction is restricted.

As a result, as in the first embodiment, even if the hinge piece 6 is damaged or the flexibility is reduced due to aging, causing relative movement or displacement in the direction in which the first side edges of the first and second split cases 2A, 2B move apart, such relative movement or displacement is prevented. Therefore, the cylindrical container shape of the core case 2 is maintained, the mutual adhesion of the pair of split cores 3A, 3B that are internally supported is maintained, the ferrite loop is secured, and the noise absorption effect is maintained.

(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 the equivalent parts to the third embodiment, and the description thereof will be omitted. In particular, since the dimension of the core case 2 in the axial direction is increased, the hinge pieces 6 are provided at two positions spaced apart in the axial direction, and the main engagement portions 4 are also provided at two positions in the axial direction.

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. Meanwhile, 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 secondary engagement portion 5.

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. In other words, the first side edges of the first separate case 2A and the second separate case 2B are connected to each other by the secondary 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.

As a result, even if at least one of the pair of hinge pieces 6 is damaged, or if the flexibility of the first and second split cases 2A, 2B decreases due to aging and the first side edges of the first and second split cases 2A, 2B move or displace in a direction that separates them, relative movement or displacement of the first and second split 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 split cores 3A, 3B that are supported internally is maintained, a ferrite loop surrounding the electric wire is secured, and the noise absorption effect is maintained.

(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 taken along the line b5-b5 of FIG. 12(a). In the fifth embodiment, parts equivalent to those in the fourth embodiment are given the same reference numerals, and the description thereof is omitted. 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.

On the other hand, the secondary engagement portion 5 in the fifth embodiment is disposed at the midpoint 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 the 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 secondary engagement portion 5.

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. In other words, 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 axial direction.

As a result, even if one or both of the pair of hinge pieces 6 are damaged, or if the flexibility of the first and second split cases 2A, 2B decreases due to aging and the first side edges of the first and second split cases 2A, 2B move or displace in a direction that separates them, the relative movement or displacement of the first and second split cases 2A, 2B is prevented, the cylindrical container shape of the core case 2 is maintained, and the mutual adhesion of the pair of split cores 3A, 3B is maintained, ensuring a ferrite loop surrounding the electric wires, and maintaining the noise absorption effect.

In the fifth embodiment, the secondary engagement portion 5 is provided at only one location, at the middle position in the axial direction of the core case 2, so that the configuration of the secondary engagement portion 5 can be simplified. On the other hand, since the secondary 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 will be relatively lower compared to the configurations of the first to fourth embodiments in which secondary engagement portions are provided at both ends in the axial direction. However, since the dimension in the axial direction where the engagement protrusion 58 and the engagement hole 59a engage can be designed to be larger compared to the first to fourth embodiments, the overall connecting force can be made to be about the same as the first to fourth embodiments.

In the above-described embodiments 1 to 5, various modifications are possible, particularly with respect to the engagement holes and engagement protrusions that constitute the secondary engagement portion. For example, the engagement pieces and engagement holes in embodiments 1, 3, and 5 may be provided in the first separate case, and the engagement protrusions may be provided in the second separate case. Also, in embodiment 5, engagement protrusions may be provided in both the first separate case and the second separate case.

Reference Signs List 1, 1A to 1D Noise absorbing device 2 Core case 2A First split case 2B Second split case 3 Ferrite core 3A, 3B Split core 4 Main engagement portion 5 Second engagement portion 6 Hinge piece

Claims (4)

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 . The noise absorbing device according to claim 1, wherein the main engagement portion comprises an engagement protrusion provided on the second side edge of one of the first and second separate cases, and an engagement piece provided on the second side edge of the other of the first and second separate cases and having an engagement hole that engages with the engagement protrusion. 3. The noise absorbing device according to claim 1, wherein the auxiliary engagement portions are disposed on end walls on both sides in the axial direction of the first and second separate cases. 4. The noise absorbing device according to 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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