Noise suppression cable, core assembly, and electrical device

A noise suppression cable includes an electrical wire, a first magnetic material including a pair of first surfaces formed along an axis direction of the electrical wire and a convex portion projecting from the first surfaces, and a second magnetic material including a pair of second surfaces disposed on a periphery of the electrical wire, the pair of the second surfaces contacting the pair of the first surfaces such that a tubular shape is formed by the first and second magnetic materials. The first magnetic material and the second magnetic material are configured to generate a compression stress in the convex portion of the first magnetic material by receiving an external force so as to reduce a relative permeability of the convex portion.

The present application is based on Japanese patent application No. 2014-029737 filed on Feb. 19, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a noise suppression cable, a core assembly used for the noise suppression cable and an electrical device using the noise suppression cable.

2. Description of the Related Art

For suppressing a radiation noise from a cable, a noise suppression cable has been proposed which has a signal wire, a dielectric layer disposed outside the signal wire, and a shield layer disposed outside the dielectric layer and a magnetic material layer disposed outside the shield layer, the magnetic material layer of a material including a ferrite (e.g., refer to JP-A-H06-181012).

For detecting the disconnection of an electrical wire, a disconnection detection device has been proposed which has a voltage detection part detecting a voltage value, a voltage storage part storing a voltage value detected by the voltage detection part when the power is supplied by a power supply part, and an abnormality detection part detecting an abnormality in parts from the power supply part to a power receiving part by comparing a voltage value stored in the voltage storage part and a voltage detected by the voltage detection part (e.g., refer to JP-A-2012-255747).

SUMMARY OF THE INVENTION

The noise suppression cable disclosed in JP-A-H06-181012 can suppress the radiation noise, but cannot control the emission direction of the radiation noise. For this reason, in order to detect the signal-wire disconnection of the noise suppression cable, the disconnection detection device disclosed in JP-A-2012-255747 may be further needed. Thus, a problem may arise that the detection of the signal-wire disconnection is complicated in device construction and operation.

It is an object of the invention to provide a noise suppression cable that is capable of suppressing the radiation noise and controlling the emission direction of the radiation noise, as well as a core assembly used for the noise suppression cable.

It is another object of the invention to provide an electrical device that is capable of suppressing the radiation noise and detecting the signal-wire disconnection with a simple construction.

(1) According to one embodiment of the invention, a noise suppression cable comprises:

an electrical wire;

a first magnetic material comprising a pair of first surfaces formed along an axis direction of the electrical wire and a convex portion projecting from the first surfaces; and

a second magnetic material comprising a pair of second surfaces disposed on a periphery of the electrical wire, the pair of the second surfaces contacting the pair of the first surfaces such that a tubular shape is formed by the first and second magnetic materials,

wherein the first magnetic material and the second magnetic material are configured to generate a compression stress in the convex portion of the first magnetic material by receiving an external force so as to reduce a relative permeability of the convex portion.

In the above embodiment (1) of the invention, the following modifications and changes can be made.

(i) The second magnetic material further comprises a concave portion corresponding to the convex portion in the second surfaces, and

wherein a height of the convex portion from the first surface is more than a depth of the concave portion from the second surface.

(ii) The convex portion is disposed at one of the pair of the first surfaces, and wherein the concave portion is disposed at one of the pair of the second surfaces.

(2) According to another embodiment of the invention, a core assembly comprises the first magnetic material and the second magnetic material according to the above embodiment (1).

(3) According to another embodiment of the invention, an electrical device comprises:

the noise suppression cable according to the embodiment (1);

a detection element to detect a magnetic flux emitted from the noise suppression cable; and

a substrate on which the noise suppression cable and the detection element are mounted.

Effects of the Invention

According to one embodiment of the invention, a noise suppression cable can be provided that is capable of suppressing the radiation noise and controlling the emission direction of the radiation noise, as well as a core assembly used for the noise suppression cable. Also, according to another embodiment of the invention, an electrical device can be provided that is capable of suppressing the radiation noise and detecting the signal-wire disconnection with a simple construction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the embodiments according to the invention will be explained referring to the drawings. Further, in each of the drawings, with regard to the components having the substantially same function, the same reference signs will be used, and the detail explanation will be omitted.

First Embodiment

FIG. 1is a perspective view schematically showing a noise suppression cable according to a first embodiment of the invention.FIG. 2is a cross-sectional view taken along the line A-A inFIG. 1.

The noise suppression cable1includes internal conductors2constituted of a plurality (7 in the embodiment) of conductors which are stranded, an insulating layer3covering the periphery of a plurality of the internal conductors2so as to insulate the internal conductors, an external conductor layer4formed on the periphery of the insulating layer3, a resin tape layer5formed on the periphery of the external conductor layer4, a magnetic material tape layer6formed on the periphery of the resin tape layer5, a sheath7formed on the periphery of the magnetic material tape layer6as an insulating protective layer, the sheath7being comprised of a resin or the like, a core assembly8formed on the periphery of the sheath7, and a pair of fixtures9A,9B configured to fix the core assembly8to the sheath7by fastening a screw. Further, the resin tape layer5, the insulating layer3, the external conductor layer4, the resin tape layer5, the magnetic material tape layer6, and the sheath7are one example of an electrical wire.

The internal conductors2are signal wires constituted of a metal such as a copper alloy, and for example, to transmit a signal of 1 kHz to 10 kHz. Further, the internal conductors2may be constituted of a single wire. In addition, each conductor of the internal conductors2can be covered. The insulating layer3is formed by, for example, an extrusion molding by using a vinyl chloride resin, an ethylene-vinyl acetate copolymer, a fluorine based resin, a silicone based resin or the like.

The external conductor layer4is formed by, for example, braiding thin wires comprised of a metal such as a copper alloy, so as to be connected to a ground of a device or the like to which the noise suppression cable1is connected.

The resin tape layer5is formed by, for example, by winding a resin tape on the periphery of the external conductor layer4along the longitudinal direction of the noise suppression cable1. As the resin tape, for example, a tape comprised of a resin such as a polyethylene terephthalate (PET) resin, a polypropylene based resin can be used.

The sheath7is formed by, for example, similarly to the insulating layer3, an extrusion molding by using a vinyl chloride resin, an ethylene-vinyl acetate copolymer, a fluorine based resin, a silicone based resin or the like. Further, the sheath7and the insulating layer3can be constituted of a heat shrinkable tube or the like.

The fixture9A includes a main body90ahaving an almost C-shape and seat portions90bdisposed on both ends of the main body90a. In the seat portion90b, a hole (not shown) through which a screw91is passed is formed. The fixture9B includes a main body90ahaving an almost C-shape and seat portions90cdisposed on both ends of the main body90a. In the seat portion90c, a screw hole (not shown) with which a screw91is fastened is formed. The fixtures9A,9B are comprised of, for example, a metal such as a carbon steel.

FIG. 3Ais a transverse cross-sectional view schematically showing a principal part of a core assembly before assembly.FIG. 3Bis a perspective view schematically showing a principal part of a core assembly before assembly. The core assembly8has, for example, an almost cylindrical shape in cross-section, and be divided into two parts by a pair of first surfaces81a,81band a pair of second surfaces82a,82balong the axis direction of the almost cylindrical shape. The core assembly8is configured such that a first magnetic material81formed in an almost arc shape and a second magnetic material82formed in an almost arc shape similarly to the first magnetic material81are combined with each other in the first and second surfaces81a,81b,82a,82b. Further, the cross-sectional shape of the core assembly8is not particularly limited so long as it is a tubular shape, but for example, it may be a polygonal shape such as a rectangular shape or a rectangular shape of which corners are rounded.

In order to suppress radiation noise, it is exemplary that the first and second magnetic materials81,82are comprised of a soft magnetic material that has a small coercive force and a high permeability. As the soft magnetic material, for example, an amorphous alloy such as a Co-based amorphous alloy, a Fe-based amorphous alloy; a ferrite such as a Mn—Zn-based ferrite, a Ni—Zn-based ferrite, a Ni—Zn—Cu-based ferrite; a soft magnetic metal such as a Fe—Ni-based alloy (Permalloy), a Fe—Si—Al-based alloy (Sendust), a Fe—Si-based alloy (silicone steel); and the like can be used. The first and second magnetic materials81,82are manufactured by, for example, molding powder of the above-mentioned soft magnetic material and sintering the molded soft magnetic material.

The first magnetic material81has a plurality (6 in the embodiment) of convex portions811having a triangular shape in cross-section and projecting from the first surface81a. The second magnetic material82has a plurality (6 in the embodiment) of concave portions821on the second surface82a, the concave portions821corresponding to a plurality of the convex portions811of the first magnetic material81and having a triangular shape in cross-section. Further, the shape of the convex portion811may be a conical shape, a columnar shape, a prismatic shape or the like.

The convex portion811and the concave portion821are formed in plural rows (2 rows in the embodiment) at intervals along the axis direction of the core assembly8. The convex portion811has a shape that the height (h1) from the first surface81ais larger than the depth (h2) of the concave portion821from the second surface82a. It is exemplary that a difference between the height (h1) of the convex portion811and the depth (h2) of the concave portion821falls within the range of approximately 0.05 mm to approximately 0.5 mm. Further, the one or not less than seven convex portion811and concave portion821may be formed on the first surface81aand the second surface82a. In addition, the convex portion811and the concave portion821may be also formed on the first surface81band the second surface82b. Further, the convex portion811and the concave portion821may be formed continuously in the axis direction of the core assembly8.

The core assembly8is assembled, for example, as follows. First, the sheath7of the noise suppression cable1is sandwiched, in a predetermined position thereof, between the first magnetic material81and the second magnetic material82. Next, the first and second magnetic materials81,82are held, in the outer periphery thereof, by the fixtures9A,9B and the screws are fastened. Due to this, the first and second magnetic materials81,82themselves are pressed in a direction approaching each other, and the convex portions811of the first magnetic material81are fitted in the concave portions821of the second magnetic material82. Furthermore, when the screws91are fastened, the first surfaces81a,81band the second surfaces82a,82bare brought into contact with each other, and compression stress occurs in the convex portion811and the concave portion821. Parts of the convex portion811and the concave portion821in which compression stress occurs are reduced in the relative permeability in comparison with the parts of the first and second magnetic materials81,82in which compression stress does not occur.

(Action of Noise Suppression Cable)

Next, an action of the noise suppression cable1is explained. When the internal conductor2of the noise suppression cable1transmits signals of for example, 1 kHz to 10 MHz, the signals transmitted through the internal conductor2generate magnetic flux inside of the core assembly8in the circumferential direction of the core assembly8.

A part of the magnetic flux generated in the core assembly8is emitted from the regions of the first and second magnetic materials81,82in which relative permeability is reduced to the normal direction of the core assembly8, namely to the “B” direction shown inFIG. 1from the first and second surfaces81a,82alocated in the one side.

(Advantageous Effect of First Embodiment)

According to the embodiment, the following advantageous effect is provided.

(1) By generating compression stress in a part of the core assembly8mounted on the electric wire so as to reduce relative permeability, the magnetic flux (radiation noise) can be exteriorly emitted from the part thereof in which the relative permeability is reduced. Namely, it becomes possible to control the direction of the radiation noise emitted from the core assembly8.
(2) By forming the convex portion811and the concave portion821on the first and second surfaces81a,82alocated in the one side, it becomes possible to emit the core magnetic flux from the first and second surfaces81a,82alocated in the one side, and simultaneously to control the magnetic flux so as not to leak from the first and second surfaces81b,82blocated in the other side of the core assembly8.

Second Embodiment

FIG. 4is a top view schematically showing a control substrate according to the second embodiment of the invention. The control substrate10according to the embodiment is a substrate configured such that the noise suppression cable1according to the first embodiment is mounted. Hereinafter, different points from the first embodiment will be mainly explained.

The control substrate10according to the embodiment is mounted on, for example, an electrical device so as to control each part of the electrical device. The control substrate10includes a CPU11configured to execute a predetermined processing based on a program stored in a storage part not shown, a connection part12configured to connect the noise suppression cable1to the control substrate10, a magnetic sensor13configured to detect the magnetic flux emitted from the core assembly8of the noise suppression cable1and a printed circuit board100configured such that the CPU11, the connection part12, the magnetic sensor13and the noise suppression cable1are mounted thereon. To the end part opposite to the connection part12of the noise suppression cable1, for example, an electrical device not shown is connected. Further, the magnetic sensor13is one example of the detection element.

The magnetic sensor13is arranged on the side of the first and second surfaces81a,82alocated in the one side of the core assembly8, and the CPU11is arranged on the side of the first and second surfaces81b,82blocated in the other side thereof.

(Operation of Control Substrate)

Next, one example of an operation of the control substrate10is explained.

The CPU11is configured to transmit signals to the noise suppression cable1via the connection part12when executing a predetermined processing, and simultaneously to receive signals transmitted from the other electrical device or the like via the noise suppression cable1.

The magnetic sensor13is configured to detect a magnetic flux density based on the magnetic flux C emitted from the first and second surfaces81a,82aso as to output the detection result to the CPU11.

The CPU11is configured to compare the magnetic flux density detected by the magnetic sensor13and the threshold value of the magnetic flux density, and in case of judging that the magnetic flux density detected is lower than the threshold value, to decide that signals do not flow through the noise suppression cable1, and in case of judging that the magnetic flux density detected is higher than the threshold value, to decide that signals flow through the noise suppression cable1. The CPU is configured to judge that disconnection of the internal conductor2of the noise suppression cable1or breakdown of the connection part12and the like occur, in case of detecting no signals flowing through the noise suppression cable1by the magnetic sensor13in spite of outputting signals to the noise suppression cable1.

The CPU11is configured to display an occurrence of disconnection or breakdown on a screen not shown or the like when judging that disconnection of the internal conductor2of the noise suppression cable1or breakdown of the connection part12and the like occur. Further, the occurrence of disconnection or breakdown may be notified by a buzzer or the like.

(Advantageous Effect of Second Embodiment)

According to the embodiment, the following advantageous effect is provided.

(1) By mounting the noise suppression cable1including the core assembly8on the control substrate10, it becomes possible to detect disconnection of the internal conductor2of the noise suppression cable1or breakdown of the connection part12and the like based on the magnetic flux emitted from the noise suppression cable1.
(2) By controlling the direction of the magnetic flux (radiation noise) generated from the noise suppression cable1, it becomes possible to suppress the CPU or the like arranged on the side opposite to the magnetic sensor13from being exposed to the magnetic flux.
(3) With a small number of components and a simple configuration, it becomes possible to suppress the radiation noise, and simultaneously to detect disconnection of the internal conductor2of the noise suppression cable1or breakdown of the connection part12and the like.

Although the invention has been described with respect to the specific embodiments for complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth. For example, the noise suppression cable1may be a cable that does not include the resin tape layer5and the magnetic material tape layer6.

In addition, a configuration may be adopted that the second magnetic material82does not include the concave portions821, and the convex portion811of the first magnetic material81is projected from the first surface81awithin the range of approximately 0.05 mm to approximately 0.5 mm.

In addition, in the second embodiment, a configuration may be also adopted that a noise level of the radiation noise generated from the noise suppression cable1is detected based on the magnetic flux density detected by the magnetic sensor13.

In addition, a configuration may be also adopted that for example, an antenna is connected to the end part opposite to the connection part12of the noise suppression cable1, and the control substrate10is configured to input an electric wave received by the antenna, and simultaneously to supply electric power to the antenna. Due to this, it becomes possible to detect disconnection of the internal conductor2of the noise suppression cable1or the like in accordance with a detection result of the magnetic flux density by the magnetic sensor13based on the electric wave.