Electric noise absorber

• US 5,343,184 A
• Filed: 10/16/1992
• Issued: 08/30/1994
• Est. Priority Date: 05/29/1989
• Status: Expired due to Term

• Current Assignee: Kitagawa Industries Company Limited
• Original Assignee: Kitagawa Industries Company Limited
• Inventors: Matsui, Kazuhiro, Kitagawa, Hiroji
• Primary Examiner(s): Kozma, Thomas J.
• Application Number:
  US07/962,067
• Time in Patent Office: 683 Days
• Field of Search: 174/92, 174/65 R, 336/174, 336/175, 336/176, 336/212, 336/92, 336/83, 336/178, 333/12, 333/185, 324/127
• US Class Current: 336/92
• CPC Class Codes: H01F 17/06 with core substantially closed in itself, e.g. toroid
• CPC Class Codes: H01F 2017/065 Core mounted around conductor to absorb noise, e.g. EMI filter
• CPC Class Codes: H01F 27/027 specially adapted for combination of signal type inductors or transformers with electronic circuits, e.g. mounting on printed circuit boards
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus

Abstract

An electric noise absorber comprising at least two ferrite pieces having abutting planes, at least two case members containing the ferrite pieces respectively and being closed by means of engagement members, and a spring member provided in at least one of the case members for pressing the ferrite pieces against each other when the case members are closed. Since the case members for keeping the ferrite pieces in appropriate positions and the spring member for pushing up the ferrite pieces for close contact are separately molded, the case members are bestowed with strength and the spring member with elasticity, both suitable for their own purposes. The case members requires no apertures for biasing members and therefore outside magnetic substance is prevented from contacting with the ferrite pieces contained in the case members.

Another type of electric noise absorber comprising longitudinally divided pieces of magnetic substance shaped to surround the periphery of an electric cable when closed, and magnetic fluid applied to at least one of abutting planes of the divided pieces for securely contacting the abutting planes with each other. Even if the abutting planes are rough and/or are not exactly horizontal surfaces, the magnetic fluid allows the ferrite pieces to be closed with no gaps between them. Consequently, the ferrite pieces keep substantially as low impedance as that of a non-divided ferrite piece.

Claims

1. An electric noise absorber for attenuating electric noise on an electric cable, the noise absorber comprising:

two bodies of magnetic material movable relative to each other, each magnetic body having an abutment surface which is movable towards and away from the abutment surface of the other magnetic body;

fastening means including (i) lockable engagement means for, when locked, attaching the bodies of magnetic material together around an electric cable with the abutment surfaces facing each other and (ii) means for unlocking the fastening means to detach the bodies of magnetic material from around an electric cable and thereby to allow the abutment surfaces to move away from facing each other; and

means comprising a deformable magnetic coating for, when deformed, providing a smooth abutment plane for the abutment surfaces, the deformable magnetic coating including at least one coating on one of the abutment surfaces, the deformable magnetic coating being in contact with both of the abutment surfaces when the abutment surfaces face each other and the bodies of magnetic material are attached together around an electric cable to deform the magnetic coating between the abutment surfaces, the deformable magnetic coating in the form of a nonhardening, liquid colloidal solution which does not change state being in contact with each of the abutment surfaces when the bodies of magnetic material are detached from around an electric cable and the abutment surfaces are moved away from facing each other.

2. An electric noise absorber of claim 1 wherein the deformable magnetic coating is made from a colloidal solution of ferromagnetic grains dispersed in an non-magnetic solution.

3. An electric noise absorber of claim 1 wherein the fastening means further includes two cases members which are relatively movable into a closed position, each of the case members receiving a magnetic body, the case members being retained in their closed position when the engagement means is locked.

4. An electric noise absorber for attenuating electric noise on an electric cable, the noise absorber comprising:

two bodies of magnetic material movable relative to each other, each magnetic body having an abutment surface which is movable towards and away from the abutment surface of the other magnetic body;

fastening means including (i) lockable engagement means for, when locked, attaching the bodies of magnetic material together around an electric cable with the abutment surfaces facing each other and (iii) means for unlocking the means for unlocking the engagement means to detach the bodies of magnetic material from around an electric cable and thereby to allow the abutment surfaces to move away from facing each other;

a first deformable magnetic coating including at least one coating on one of the abutment surfaces; and

a second deformable magnetic coating separate from the first magnetic coating and including at least one coating on the other one of the abutment surfaces;

the first and second deformable magnetic coatings being in contact with each other and deforming to provide a smooth abutment plane for the abutment surfaces when the abutment surfaces face each other and the bodies of magnetic material are attached together around an electric cable, the first and second deformable magnetic coatings in the form of a nonhardening, liquid colloidal solution which does not change state and being spaced apart from each other when the bodies of magnetic material are detached from around an electric cable and the abutment surfaces are moved away from facing each other.

5. An electric noise absorber of claim 4 wherein the first and second deformable magnetic coatings are made from a colloidal solution of ferromagnetic grains dispersed in a non-magnetic solution.

6. An electric noise absorber of claim 4 wherein the fastening means further includes two case members which are relatively movable into a closed position, each of the case members receiving a magnetic body, the case members being retained in their closed position when the engagement is locked.