Noise absorption device

Abstract

The present invention provides a noise absorption device having a ferrite core that can suppress vibrations between ferrite cores even when attached to a high-voltage cable with a rated voltage of 600V or higher. [Solution] The present invention provides a noise absorption device that can be attached to a power cable, comprising: first and second split cylindrical first and second ferrite cores for clamping a power cable; first and second core cases for housing the first and second ferrite cores; and a fixing device for connecting the first and second core cases so that the joining surfaces of the first and second ferrite cores are in close contact with each other, wherein rubber-like first and second vibration damping members that press the first and second ferrite cores with a surface are each arranged between the first and second core cases and the first and second ferrite cores for a length of 70% or more of the length of the first and second ferrite cores in the direction in which the power cable is guided.

Description

Technical Field

[0001] The present invention relates to a noise absorption device that can be attached to the outer periphery of a power cable, and more particularly to a noise absorption device that can be used even for a high-voltage cable that is used on the output side of a switchboard or in a distribution board, has a high operating voltage, and has a relatively large outer diameter.

Background Art

[0002] Conventionally, a technique is known in which a noise absorption device in which a solid ferrite core or a ferrite core is held in a resin case is attached to a cable of an electronic device or the like to remove unnecessary noise generated by the cable.

[0003] For example, in Japanese Utility Model Publication No. 7-3677 (Patent Document 1), in order to attach a ferrite core to a cable connected to an electronic device such as a computer or a copying machine, a spring member is provided in a part of the storage portion of a resin case, and the joining surfaces of two split cylindrical ferrite cores are brought into close contact with each other by the pressing force of such a spring member, so that a noise absorption device capable of sandwiching the cable and removing the noise of the cable is disclosed.

[0004] Further, in Japanese Patent Application Laid-Open No. 2002-299125 (Patent Document 2), in order to attach a ferrite core to a cable connected to an electronic device such as a computer or a copying machine, a long spring member is disposed over the entire length of the cable guiding direction of the storage portion of the resin case, and the joining surfaces of two split cylindrical ferrite cores are uniformly brought into close contact with each other over the entire length by the pressing force of such a spring member, so that a noise absorption device capable of sandwiching the cable and more stably removing the noise of the cable is disclosed.

[0005] Furthermore, International Publication No. WO2022 / 079820 (Patent Document 3) discloses a noise filter (noise absorption device) that uses two split cylindrical ferrite cores, which have been made highly hard by incorporating a predetermined amount of rhodium, to sandwich a cable, and then uses a strong fastener such as a cable tie to tightly seal the joint surfaces of the ferrite cores together, thereby removing noise from the cable.

[0006] Furthermore, as described in Patent Document 3, noise absorption devices using cylindrical ferrite cores, as described in Patent Documents 1 to 3, when attached to power cables that generate electromagnetic waves, collect the magnetic field generated by the power cable in the ferrite core, convert the magnetic energy into heat due to magnetic loss in the ferrite core, and release the heat into the external atmosphere through a resin case, thereby attenuating the noise. Therefore, the noise absorption devices described in Patent Documents 1 to 3 not only remove unwanted noise generated in the cable, but also attenuate such noise (reactive power), allowing a clean current to flow through electronic devices, reducing the burden on the electronic devices and thus reducing power consumption. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Publication number 7-3677 [Patent Document 2] Japanese Patent Publication No. 2002-299125 [Patent Document 3] International Publication No. WO2022 / 079820 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, the noise absorption devices described in Patent Documents 1 and 2 are both intended to remove noise generated in cables connected to electronic devices such as computers and photocopiers, and are usually attached to low-voltage cables with a rated voltage of less than 600V.

[0009] Therefore, the noise absorption devices described in Patent Documents 1 and 2 had a problem in that, when attached to a main line connecting a distribution board (cubicle) that steps down 6600V electricity sent from a power plant through a substation to 100V or 200V electricity, and a distribution board that has a leakage breaker and safety breaker and further distributes the electricity sent from the distribution board to lighting, outlets, motors, etc. inside a home (indoors), or to a power cable within the distribution board, or in other words, a high-voltage cable with a rated voltage of 600V or more, the two ferrite cores, which are divided into two parts, vibrate violently due to the high-voltage current flowing through the cable, ultimately destroying the noise absorption device and its surrounding equipment.

[0010] In other words, the noise absorption devices described in Patent Documents 1 and 2 had a problem in that the two divided ferrite cores vibrated violently because they lacked sufficient adhesion between the joining surfaces of the ferrite cores, the surface roughness of the joining surfaces, and the adhesion accuracy, such as slight misalignment or gaps between the joining surfaces, which are necessary when the noise absorption device is attached to a high-voltage cable carrying high-voltage current. Furthermore, the above-mentioned problems caused by the adhesion force and adhesion accuracy of the joining surfaces of the ferrite cores were also common issues that arose when the noise filter (noise absorption device) described in Patent Document 3 was attached to a high-voltage cable carrying high-voltage current.

[0011] Therefore, the present invention has been made in view of the above-mentioned problems, and aims to provide a noise absorption device having two divided ferrite cores that can suppress vibrations between the ferrite cores even when attached to a high-voltage cable with a rated voltage of 600V or more. [Means for solving the problem]

[0012] To solve the above problems, the inventors diligently studied the shape of the ferrite core and the structure of the core case that holds the ferrite core in order to obtain high adhesion at the joint surface of the two divided ferrite cores. As a result, they discovered that instead of using a material with only elastic elements such as a spring or a resin cable tie to press the outer circumference of the two divided ferrite cores by point contact or line contact to bring the joint surfaces of the ferrite cores into close contact, using a material that combines elastic and damping elements such as silicon or urethane to press the outer circumference of the two divided ferrite cores by surface contact makes it less susceptible to the influence of the adhesion accuracy of the joint surface of the ferrite cores, thus enabling high adhesion between the joint surfaces of the ferrite cores, and thus completed the present invention.

[0013] In other words, according to the present invention, a noise absorption device that can be attached to a power cable comprises: a first ferrite core in the shape of a half-split cylinder for clamping a power cable; a second ferrite core in the shape of a half-split cylinder that forms a cylinder when joined with the first ferrite core; a first core case for housing the first ferrite core; a second core case for housing the second ferrite core; and a fastener for connecting the first core case and the second core case so that the joining surface of the first ferrite core and the joining surface of the second ferrite core are in close contact. The noise absorption device is provided, characterized in that a sheet-like first vibration damping member is placed between the first core case and the first ferrite core to press against the first ferrite core with a surface length of 70% or more of the length of the first ferrite core in the direction in which the power cable is guided, and a sheet-like second vibration damping member is placed between the second core case and the second ferrite core to press against the second ferrite core with a surface length of 70% or more of the length of the second ferrite core in the direction in which the power cable is guided.

[0014] Furthermore, the first vibration damping member and / or the second vibration damping member described above are preferably made of a silicone material or a urethane material. If the first vibration damping member and / or the second vibration damping member are made of a silicone material, the hardness of the silicone material is preferably 30 to 60 according to the International Rubber Hardness (IRHD) values ​​in accordance with JIS K6253.

[0015] Furthermore, the fasteners may be resin cable ties or the like that connect the first core case and the second core case at at least two points on their respective outer circumferences.

[0016] In this invention, the joint surfaces of the two divided ferrite cores are not directly pressed against the outer periphery of the ferrite core by an elastic element such as a spring or resin cable tie, but rather indirectly pressed against the outer periphery of the ferrite core by the pressing force generated by the fixing device via the core case and a vibration damping member that combines an elastic element and a damping element, such as a silicon material. Furthermore, the pressing force to the outer periphery of the ferrite core is not transmitted by point contact or line contact such as a spring or resin cable tie, but by surface contact by placing a vibration damping member on the outer periphery of the ferrite core with a certain width and a length of 70% or more of the total length of the ferrite core. Preferably, the "certain width" of the vibration damping member is the length of the vibration damping member in the direction perpendicular to the direction in which the power cable is guided, that is, a length of 70% or more of the width direction of the pressed surface of the ferrite core.

[0017] Therefore, in this invention, the pressing force generated by the fixing device is transmitted to the outer periphery of the two divided ferrite core so that a uniform adhesion force is generated across the entire bonding surface of each joint, or in other words, so that one bonding surface uniformly presses against the other bonding surface over its entire surface.

[0018] In particular, as described in Patent Document 3, when the outer periphery of a 2-part ferrite core is fastened together using a resin cable tie or the like, the adhesion force and pressing force between the joint surfaces located directly below the cable tie become greater than the adhesion force and pressing force between joint surfaces in other areas, resulting in an uneven distribution of adhesion force and pressing force even within the same joint surface. However, in the present invention, the pressing force transmitted to the outer periphery of the ferrite core by fastening with a cable tie is uniformly distributed over a certain width over a length of at least 70% of the total length of the ferrite core via the core case and vibration damping member, so that a uniform adhesion force and pressing force can be obtained over substantially the entire joint surface. Conversely, if the length of the vibration damping member is less than 70% of the total length of the ferrite core, a uniform adhesion force and pressing force cannot be obtained at the joint surface.

[0019] Furthermore, in this invention, a vibration damping member such as a silicon material that combines an elastic element and a damping element is used as the member that presses the ferrite core. Therefore, even if a high-voltage current flows through the high-voltage cable equipped with a noise absorption device, the vibration between the ferrite cores is absorbed by the damping element, and a high degree of contact between the joint surfaces is maintained by the pressing of the elastic element.

[0020] Therefore, in order to suppress vibrations of the ferrite core, the noise absorption device of the present invention can be applied to high-voltage cables carrying high-voltage currents even with the same level of contact accuracy between the ferrite core's bonding surfaces that was previously only acceptable when the noise absorption device was attached to a low-voltage cable carrying a low-voltage current.

[0021] In this specification, "elastic element" refers to a material that can temporarily store force, such as a spring or a resin cable tie, and "damping element" refers to a material that can absorb force by converting it into heat, such as silicon or urethane. Furthermore, in this invention, "pressing with a surface" includes pressing with a flat surface, pressing with a curved surface, or both, as long as the surface can make contact with the outer circumference of the ferrite core in a manner that matches its shape.

[0022] In the present invention, in order to increase the adhesion between the joint surfaces of the two-split ferrite cores, in the first core case and the second core case, when the joint surface of the first ferrite core and the joint surface of the second ferrite core are brought into close contact with each other by a fixture, it is preferable that a gap allowing tightening by the fixture is provided between the end of the first core case and the end of the second core case.

[0023] In the present invention, on the outer peripheral portion of the first ferrite core, a first pressed surface parallel to the joint surface of the first ferrite core is formed for pressing by the first vibration damping member, and in the accommodating portion of the first core case, a first pressing surface arranged parallel to the first pressed surface for pressing the first vibration damping member is formed. And on the outer peripheral portion of the second ferrite core, a second pressed surface parallel to the joint surface of the second ferrite core is formed for pressing by the second vibration damping member, and in the accommodating portion of the second core case, a second pressing surface arranged parallel to the second pressed surface for pressing the second vibration damping member is formed, which is preferable.

[0024] Further, it is more preferable that the first vibration damping member and the second vibration damping member are arranged so as to be parallel to and face the joint surface of the first ferrite core and the joint surface of the second ferrite core.

[0025] When the first and second pressed surfaces parallel to the joint surfaces of the first and second ferrite cores are formed on the outer peripheral portions of the first and second ferrite cores, the pressing force generated by the fixture is efficiently input in a direction orthogonal to the first and second pressed surfaces, and the pressing force input from the first and second pressed surfaces is efficiently transmitted in a direction orthogonal to the joint surfaces of the first and second ferrite cores parallel to the first and second pressed surfaces. Therefore, the joint surfaces of the first and second ferrite cores to which the pressing force is transmitted are strongly pressed against the other joint surface facing each other and can be strongly adhered to the other joint surface.

[0026] Furthermore, the housing portions of the first and second core cases have first and second pressing surfaces formed parallel to the first and second pressed surfaces of the first and second ferrite cores, and flat, sheet-like first and second vibration damping members are placed between the first and second pressing surfaces and the first and second pressed surfaces. Therefore, the pressing force generated by the fixing device, even if it is a localized pressing force generated by a cable tie or the like, is uniformly distributed across the entire plane of the vibration damping member by deforming the first and second vibration damping members via the first and second pressing surfaces. As a result, the pressing force generated by the fixing device becomes a uniform surface pressure through the first and second vibration damping members, pressing the first and second pressed surfaces and being uniformly transmitted to the joint surfaces of the first and second ferrite cores. Thus, the first and second joint surfaces to which the pressing force has been transmitted can be precisely and uniformly in contact with the other opposing joint surface.

[0027] As described above, the noise absorption device of the present invention suppresses vibration of the ferrite core by pressing the outer periphery of the two divided ferrite cores together through surface contact, thereby strongly and uniformly bringing the joining surfaces of the ferrite cores into close contact. Therefore, it can be applied to high-voltage cables carrying high-voltage currents with a rated voltage of 600V or higher and an outer diameter of 15 to 35 mm. [Effects of the Invention]

[0028] According to the present invention, even if the pressing force is generated by a resin cable tie or the like, it can be uniformly distributed over a certain width over a length of 70% or more of the total length of the ferrite core via the core case and vibration damping member, and a uniform adhesion force and pressing force can be obtained over substantially the entire bonding surface.

[0029] According to the present invention, since a vibration damping member such as a silicon material that combines an elastic element and a damping element is used as the member that presses the ferrite core, even if a high-voltage current flows through the high-voltage cable equipped with a noise absorption device, the damping element can absorb vibrations between the ferrite cores, and furthermore, the pressing by the elastic element can maintain a high degree of contact between the joint surfaces.

[0030] Therefore, in order to suppress vibrations of the ferrite core, the noise absorption device of the present invention can be applied to high-voltage cables carrying high-voltage currents even with the same level of contact accuracy between the ferrite core's bonding surfaces that was previously only acceptable when the noise absorption device was attached to a low-voltage cable carrying a low-voltage current. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 is a cross-sectional view showing the longitudinal center of a noise absorption device according to one embodiment of the present invention. [Figure 2] Figure 2 shows external perspective views (a) and internal perspective views (b) of the first and second ferrite cores of the noise absorption device shown in Figure 1. [Figure 3A] Figure 3A shows a plan view (a) of the first core case of the noise absorption device shown in Figure 1, and a plan view (b) of the first core case with the first ferrite core housed inside. [Figure 3B] Figure 3B is a side view of the first core case shown in Figure 3A. [Figure 3C] Figure 3C is a bottom view of the first core case shown in Figure 3A. [Figure 3D] Figure 3D is a cross-sectional view of the AA section shown in the first core case in Figure 3A. [Figure 4A] Figure 4A shows a plan view (a) of the second core case of the noise absorption device shown in Figure 1, and a plan view (b) of the second core case with the second ferrite core housed inside. [Figure 4B] Figure 4B is a side view of the second core case shown in Figure 4A. [Figure 4C] Figure 4C is a bottom view of the second core case shown in Figure 4A. [Figure 4D] Figure 4D is a cross-sectional view of the BB section shown in the second core case of Figure 4A. [Modes for carrying out the invention]

[0032] A noise absorption device according to one embodiment of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and various modifications are possible without departing from the technical spirit of the invention. [Examples]

[0033] <Noise absorption device> Figure 1 shows a cross-sectional view of the longitudinal center of a noise absorption device 1 according to one embodiment of the present invention.

[0034] As shown in Figure 1, the noise absorption device 1 of this embodiment includes a split cylindrical first ferrite core 2a and a split cylindrical second ferrite core 2b that forms a cylindrical body when joined with the first ferrite core 2a, in order to clamp the power cable 5 (the central axis of the power cable is shown in the figure, the same applies hereinafter). The first ferrite core 2a is housed in a first core case 3a, and the second ferrite core 2b is housed in a second core case 3b.

[0035] Furthermore, sheet-like first vibration damping members 4a and second vibration damping members 4b made of silicon material are placed between the first core case 3a and the first ferrite core 2a, and between the second core case 3b and the second ferrite core 2b, so as to ensure strong and uniform contact between the joining surface 22a of the first ferrite core 2a and the joining surface 22b of the second ferrite core 2b. Fixing devices (not shown), such as resin cable ties, are attached to the outside of the first core case 3a and the second core case 3b to connect the two core cases 3a and 3b and to provide strong adhesion to the joining surfaces 22a and 22b of the first and second ferrite cores 2a and 2b.

[0036] <Filite Core> Figure 2 shows external perspective views (a) and internal perspective views (b) of the first and second ferrite cores 2a and 2b of the noise absorption device 1 shown in Figure 1. The first ferrite core 2a and the second ferrite core 2b have the same shape and are formed from the same material, mainly composed of iron oxide, by compression molding and sintering.

[0037] As shown in Figure 1, the first ferrite core 2a and the second ferrite core 2b together form a cylindrical cable guide hole 10 inside for guiding the power cable 5. Therefore, as shown in Figure 2, the first ferrite core 2a and the second ferrite core 2b have the same split cylindrical shape.

[0038] As shown in Figures 2(a) and 2(b), the split cylindrical first ferrite core 2a has a semicircular cable guide groove 20a formed on its inside, which constitutes part of the cable guide hole 10, and a planar first pressure surface 21a formed on its outside, which is pressed by the first vibration damping member 4a (Figure 1). In addition, a pair of joint surfaces 22a are formed on the outer and inner edges of the first ferrite core 2a, extending longitudinally to guide the power cable 5 while being continuous with both edges, and parallel to the first pressure surface 21a. In other words, the pair of joint surfaces 22a are formed parallel to an extension line extending radially from the central axis of the cable guide hole 10 (Figure 1) formed by the cable guide groove 20a.

[0039] The split cylindrical second ferrite core 2b has a semicircular cable guide groove 20b formed on its inside, which constitutes part of the cable guide hole 10, and a planar second pressure surface 21b formed on its outside, which is pressed by the second vibration damping member 4b (Figure 1). In addition, a pair of joint surfaces 22b are formed on the outer and inner edges of the second ferrite core 2b, extending longitudinally to guide the power cable 5 while being continuous with both edges, and parallel to the second pressure surface 21b. In other words, the pair of joint surfaces 22b are formed parallel to an extension line extending radially from the central axis of the cable guide hole 10 (Figure 1) formed by the cable guide groove 20b.

[0040] Therefore, as shown in Figure 1, the first pressed surface 21a and the second pressed surface 21b are arranged to be parallel and facing each other when the joining surface 22a of the first ferrite core 2a and the joining surface 22b of the second ferrite core 2b are aligned and in close contact with each other.

[0041] In this way, by forming first and second pressed surfaces 21a and 21b parallel to the joining surfaces 22a and 22b of the first and second ferrite cores 2a and 2b on the outer circumference of the first and second ferrite cores 2a and 2b, the pressing force transmitted by the first and second vibration damping members 4a and 4b is efficiently input in a direction perpendicular to the first and second pressed surfaces 21a and 21b, and the pressing force input from the first and second pressed surfaces 21a and 21b is also efficiently transmitted in a direction perpendicular to the joining surfaces 22a and 22b of the first and second ferrite cores 2a and 2b, which are parallel to the first and second pressed surfaces 21a and 21b. Therefore, the joint surfaces 22a and 22b of the first and second ferrite cores 2a and 2b, to which the pressing force is transmitted, are strongly pressed against the other opposing joint surface 22b and 22a, and tightly adhere to the other joint surface 22b and 22a.

[0042] <Core Case> Figure 3A shows a plan view (a) of the first core case 3a of the noise absorption device 1 shown in Figure 1, and a plan view (b) of the first core case 3a with the first ferrite core 2a housed inside. Figure 3B shows a side view of the first core case 3a shown in Figure 3A, Figure 3C shows a bottom view of the first core case 3a shown in Figure 3A, and Figure 3D shows a cross-sectional view of the AA section of the first core case 3a shown in Figure 3A.

[0043] Figure 4A shows a plan view (a) of the second core case 3b of the noise absorption device 1 shown in Figure 1, and a plan view (b) of the second core case 3b with the second ferrite core 2b housed inside. Figure 4B shows a side view of the second core case 3b shown in Figure 4A, Figure 4C shows a bottom view of the second core case 3b shown in Figure 4A, and Figure 4D shows a cross-sectional view of the BB section of the second core case 3b shown in Figure 4A.

[0044] As shown in Figures 3A to 3D, the first core case 3a has a trough-shaped housing portion 30a that curves downward to accommodate the first ferrite core 2a inside it, and a planar first pressing surface 31a is formed inside the housing portion 30a of the first core case 3a, which is arranged parallel to the first pressed surface 21a of the first ferrite core 2a in order to press the first vibration damping member 4a (Figure 1).

[0045] As shown in Figures 4A to 4D, the second core case 3b has a trough-shaped housing portion 30b that curves upward to accommodate the second ferrite core 2b inside it, and a planar second pressing surface 31b is formed inside the housing portion 30b of the second core case 3b, which is arranged parallel to the second pressed surface 21b of the second ferrite core 2b in order to press the second vibration damping member 4b (Figure 1). There are no particular limitations on the material of the first core case 3a and the second core case 3b, but in this embodiment they are made of a resin material such as polyvinyl chloride.

[0046] Thus, in the housing portions 30a and 30b of the first and second core cases 3a and 3b, first and second pressing surfaces 31a and 31b are formed parallel to the first and second pressed surfaces 21a and 21b of the first and second ferrite cores 2a and 2b described above, in order to press the first and second vibration damping members 4a and 4b. Between the first and second pressing surfaces 31a and 31b and the first and second pressed surfaces 21a and 21b, the first and second vibration damping members 4a and 4b (Figure 1) are respectively positioned. Therefore, localized pressing force generated by fasteners such as resin cable ties, which will be described later, is uniformly distributed across the entire plane of the vibration damping members 4a and 4b by deforming them via the first and second pressing surfaces 31a and 31b. Therefore, the pressing force generated by the fixing device becomes a uniform surface pressure due to the first and second vibration damping members 4a and 4b, pressing the first and second pressed surfaces 21a and 21b, and is uniformly transmitted to the joint surfaces 22a and 22b of the first and second ferrite cores 2a and 2b. As a result, the first and second joint surfaces 22a and 22b to which the pressing force has been transmitted are in close and uniform contact with the other opposing joint surfaces 22b and 22a.

[0047] In this embodiment, the inner side surface of the housing portion 30a of the first core case 3a is provided with a side support rib 300a having an end face that substantially matches the shape of the outer peripheral side surface of the first ferrite core 2a (see Figures 3A(a)(b), 3D).

[0048] The first core case 3a has semicircular locking walls 32a at its longitudinal leading and trailing ends that guide the power cable 5, in a direction perpendicular to the longitudinal direction to prevent the first ferrite core 2a from moving longitudinally within the housing 30a, and a semicircular opening 33a for guiding the power cable 5 is provided near the center of the locking wall 32a. In addition, an end face support rib 320a is provided on the inside of the locking wall 32a, having a vertical end face that substantially matches the shape of the end face of the first ferrite core 2a (see Figures 3A(a)(b), 3D).

[0049] The side support ribs 300a and end support ribs 320a of the housing portion 30a of the first core case 3a reduce the insertion resistance when setting the first ferrite core 2a into the housing portion 30a, making it easier to set. After insertion, they also function to hold the first ferrite core 2a in place within the housing portion 30a by forming a gap between the first ferrite core 2a and the housing portion 30a, preventing it from moving in any direction other than the direction in which it is pressed by the first vibration damping member 4a. Therefore, the first vibration damping member 4a can press the first ferrite core 2a and absorb its vibrations without being obstructed by the first core case 3a or its side support ribs 300a and end support ribs 320a.

[0050] On the inner side surface of the housing portion 30b of the second core case 3b, similar to the first core case 3a, side support ribs 300b are provided, having end faces that substantially match the shape of the outer peripheral side surface of the second ferrite core 2b (see Figures 4A(a)(b), 4D).

[0051] The second core case 3b has semicircular locking walls 32b at its longitudinal leading and trailing ends that guide the power cable 5, in a direction perpendicular to the longitudinal direction to prevent the second ferrite core 2b from moving longitudinally within the housing 30b, and a semicircular opening 33b for guiding the power cable 5 is provided near the center of the locking wall 32b. In addition, an end face support rib 320b is provided inside the locking wall 32b, having a vertical end face that substantially matches the shape of the end face of the second ferrite core 2b (see Figures 4A(a)(b), 4D).

[0052] The side support ribs 300b and end support ribs 320b of the housing portion 30b of the second core case 3b reduce the insertion resistance when setting the second ferrite core 2b into the housing portion 30b, making it easier to set. After insertion, they also function to hold the second ferrite core 2b in place within the housing portion 30b by forming a gap between the second ferrite core 2b and the housing portion 30b, preventing it from moving in any direction other than the direction in which it is pressed by the second vibration damping member 4b. As a result, the second vibration damping member 4b can press the second ferrite core 2b and absorb its vibrations without being obstructed by the second core case 3b or its side support ribs 300b and end support ribs 320b.

[0053] The outer sides of the first core case 3a and the second core case 3b are provided with fixing guides 34a (see Figures 3A(a)(b), 3D) and 34b (see Figures 4A(a)(b), 4D) that protrude radially from the edges, and a square-shaped through hole is formed inside the fixing guides 34a and 34b. When fastening the joint surface 22a of the first ferrite core 2a and the joint surface 22b of the second ferrite core 2b using fasteners such as cable ties, as shown in Figure 1, if the fasteners are passed through both through-holes of the fastener guides 34a and 34b and the first and second core cases 3a and 3b are fastened in the circumferential direction, the fasteners will not shift or detach from their predetermined positions on the outer circumference of the first and second core cases 3a and 3b even when high voltage current is flowing through the power cable 5. This ensures that the close contact between the first ferrite core 2a and the second ferrite core 2b, and the attachment of the noise absorption device 1 to the power cable are stably maintained.

[0054] Furthermore, it is preferable that the fasteners connect (fasten) the first core case 3a and the second core case 3b at at least two points on their respective outer circumferences so that the pressing force generated by the fasteners, such as cable ties, is transmitted uniformly to the joint surface 22a of the first ferrite core 2a and the joint surface 22b of the second ferrite core 2b without bias.

[0055] Furthermore, the outer side surface of the first core case 3a is provided with a projection 35a (see Figures 3B and 3D) that protrudes radially from the edge, and the outer side surface of the second core case 3b is provided with a hook 35b (see Figures 4B and 4D) that extends tangentially from the edge and engages with the projection 35a. In other words, the projection 35a and the hook 35b serve as a latching mechanism that detachably engages the first core case 3a and the second core case 3b.

[0056] Therefore, when bringing the joining surface 22a of the first ferrite core 2a and the joining surface 22b of the second ferrite core 2b into close contact, as shown in Figure 1, for example, the second core case 3b containing the second ferrite core 2b can be brought into contact with the first core case 3a containing the first ferrite core 2a so as to align with it, and the projection 35a of the first core case 3a can be inserted into the hook 35b of the second core case 3b and engaged. Furthermore, since the hook 35b is elastic, disengaging it radially will release the engagement with the projection 35a, allowing the first core case 3a and the second core case 3b to be separated.

[0057] <Vibration damping member> In this embodiment, as shown in Figure 1, a first vibration damping member 4a and a second vibration damping member 4b are inserted between the first ferrite core 2a and the first core case 3a, and between the second ferrite core 2b and the second core case 3b, in order to uniformly distribute the pressing force generated by the fixing device and transmit it to the first ferrite core 2a and the second ferrite core 2b.

[0058] Furthermore, in this embodiment, in order to further enhance the adhesion between the joint surfaces 22b, 22a of the two divided first and second ferrite cores 2a, 2b, the first core case 3a and the second core case 3b are provided with a gap 36 between the end of the first core case 3a and the end of the second core case 3b to allow for further tightening by the fastener when the joint surface 22a of the first ferrite core 2a and the joint surface 22b of the second ferrite core 2b are brought into close contact with the fastener.

[0059] The first and second vibration damping members 4a and 4b have an elastic function that allows them to temporarily store and disperse external forces through deformation, and a damping function that allows them to absorb external forces such as vibrations by converting them into heat or other forms of energy. Known materials such as silicone or urethane can be used without particular limitation as long as they have both functions. In the first vibration damping member 4a and the second vibration damping member 4b of this embodiment, a sheet of silicone rubber with a thickness of about 3 to 7 mm is used, and the hardness of the silicone rubber is 30 to 60 according to the International Rubber Hardness (IRHD) value in accordance with JIS K6253.

[0060] As shown by the dashed lines in Figures 3A(b) and 4A(b), the first vibration damping member 4a is positioned between the first core case 3a and the first ferrite core 2a for a length in the direction that guides the power cable of the first ferrite core 2a, i.e., 70% or more of the longitudinal length of the first pressed surface 21a of the first ferrite core 2a, and the second vibration damping member 4b is positioned between the second core case 3b and the second ferrite core 2b for a length in the direction that guides the power cable of the second ferrite core 2b, i.e., 70% or more of the longitudinal length of the second pressed surface 21b of the second ferrite core 2b.

[0061] Furthermore, the widths of the first and second vibration damping members 4a and 4b are arranged to be at least 70% of the length in the width direction of the first and second ferrite cores 2a and 2b on the first and second pressed surfaces 21a and 21b, which are perpendicular to the direction in which the power cables of the first and second ferrite cores 2a and 2b are guided.

[0062] Thus, in this embodiment, the joint surfaces 22a, 22b of the two divided first and second ferrite cores 2a, 2b are joined together by applying a pressing force generated by a fastener made of resin cable ties to the first and second core cases 3a, 3b and the first and second vibration damping members 4a, 4b made of silicone rubber that combines elastic and damping elements, thereby indirectly pressing the first and second pressed surfaces 21a, 21b on the outer periphery of the first and second ferrite cores 2a, 2b. Furthermore, the pressing force of the first and second ferrite cores 2a and 2b to the first and second pressed surfaces 21a and 21b is transmitted by surface contact by arranging the first and second vibration damping members 4a and 4b on the first and second pressed surfaces 21a and 21b, each having a length of at least 70% of the total length (length in the longitudinal direction) of the first and second ferrite cores 2a and 2b, and a length of at least 70% of the length in the width direction of the pressed surfaces 21a and 21b of the first and second ferrite cores 2a and 2b.

[0063] Therefore, in this embodiment, the pressing force generated by the fixing device is transmitted to the first and second pressed surfaces 21a and 21b of the two divided first and second ferrite cores 2a and 2b so as to generate a uniform adhesion force over the entire joint surfaces 22a and 22b, in other words, so that one joint surface 22a and 22b presses the other opposing joint surface 22b and 22a uniformly over its entire surface.

[0064] In particular, in this embodiment, the pressing force generated by the fixing device is uniformly distributed over a region having a length of at least 70% of the total length (length in the longitudinal direction) of the first and second ferrite cores 2a and 2b, and a length of at least 70% of the widthwise length of the pressed surfaces 21a and 21b of the first and second ferrite cores 2a and 2b, via the first and second core cases 3a and 3b and the first and second vibration damping members 4a and 4b. As a result, a uniform adhesion force and pressing force can be obtained over substantially the entire surface of the joint surfaces 22a and 22b.

[0065] Furthermore, in this embodiment, first and second vibration damping members 4a and 4b made of silicon material that combines elastic and damping elements are used as members that press the first and second ferrite cores 2a and 2b. Therefore, even if a high-voltage current flows through the high-voltage cable 5 to which the noise absorption device 1 is attached, the vibrations between the first and second ferrite cores 2a and 2b are absorbed by the damping element, and a high degree of contact between the joint surfaces 22b and 22a is maintained by the pressing of the elastic element.

[0066] Therefore, in order to suppress vibrations of the first and second ferrite cores 2a and 2b, the noise absorption device 1 of this embodiment can be applied to high-voltage cables 5 through which high-voltage currents flow, even if the contact accuracy between the ferrite core joints was previously only acceptable when the noise absorption device was attached to a low-voltage cable through which low-voltage currents flowed.

[0067] As described above, the noise absorption device 1 of this embodiment presses the first and second pressed surfaces 21a and 21b of the outer circumference of the two divided first and second ferrite cores 2a and 2b by surface contact, thereby strongly and uniformly bringing the joint surfaces 22b and 22a of the first and second ferrite cores 2a and 2b into close contact and suppressing vibration of the first and second ferrite cores 2a and 2b. Therefore, it can be applied to high-voltage cables 5 that carry high-voltage currents with a rated voltage of 600V or more and an outer diameter of 15 to 35 mm. [Explanation of symbols]

[0068] 1. Noise absorption device 10······Cable guide hole 2a, 2b... First and second ferrite cores 20a, 20b... Cable guide groove 21a, 21b...First and second pressed surfaces 22a,22b...Joint surface 3a, 3b... First and second core cases 30a, 30b... Storage area 300a, 300b... Side support ribs 31a, 31b...First and second pressing surfaces 32a,32b...locking wall 320a, 320b... End face support ribs 33a,33b...Opening 34a, 34b... Guide for fasteners 35a...Protrusion 35b...Hook 36...Gap 4a, 4b... First and second vibration damping members 5. Power cables (high-voltage cables)

Claims

1. A first ferrite core in the shape of a split cylinder for clamping a power cable, A split cylindrical second ferrite core, which forms a cylindrical body when joined with the first ferrite core, A first core case housing the first ferrite core, A second core case housing the second ferrite core, A fastener for connecting the first core case and the second core case such that the joining surface of the first ferrite core and the joining surface of the second ferrite core are in close contact, In a noise absorption device that can be attached to a power cable equipped with, Between the first core case and the first ferrite core, a sheet-like first vibration damping member is placed to press the first ferrite core with a surface, with a length of 70% or more of the length of the first ferrite core in the direction guiding the power cable. A noise absorption device characterized in that a sheet-like second vibration damping member is placed between the second core case and the second ferrite core, pressing the second ferrite core with a surface, for a length of 70% or more of the length of the second ferrite core in the direction in which the power cable is guided.

2. The noise absorbing device according to claim 1, characterized in that when the joint surface of the first ferrite core and the joint surface of the second ferrite core are brought into close contact by the fixing device, a gap is formed between the end of the first core case and the end of the second core case, allowing for further tightening by the fixing device.

3. A first pressing surface is formed on the outer periphery of the first ferrite core, parallel to the joining surface of the first ferrite core, for pressing with the first vibration damping member, and a first pressing surface is formed in the housing portion of the first core case, arranged parallel to the first pressing surface, for pressing with the first vibration damping member, and The noise absorption device according to claim 1, characterized in that a second press surface is formed on the outer periphery of the second ferrite core, parallel to the joint surface of the second ferrite core, for pressing with the second vibration damping member, and a second pressing surface is formed in the housing portion of the second core case, arranged parallel to the second press surface, for pressing with the second vibration damping member.

4. The noise absorption device according to claim 1, characterized in that the first vibration damping member and the second vibration damping member are arranged parallel to and facing each other with respect to the joint surface of the first ferrite core and the joint surface of the second ferrite core.

5. The noise absorption device according to claim 1, characterized in that the first vibration damping member and / or the second vibration damping member are made of a silicon material or a urethane material.

6. The noise absorbing device according to claim 5, characterized in that the hardness of the silicon material is 30 to 60 according to the International Rubber Hardness (IRHD) values ​​in accordance with JIS K6253.

7. The noise absorbing device according to claim 1, characterized in that the fastener is a cable tie that connects the first core case and the second core case at at least two locations.

8. The noise absorption device according to any one of claims 1 to 7, characterized in that the power cable has an outer diameter of 15 to 35 mm and is a high-voltage cable with a rated voltage of 600 V or more.

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