Annular magnetic body for noise control and member for noise control

Patent metadata

Field	Value
Publication number	US-12476030-B2
Application number	US-202218998122-A
Country	US
Kind code	B2
Filing date	Jul 27, 2022
Priority date	Jul 27, 2022
Publication date	Nov 18, 2025
Grant date	Nov 18, 2025

Abstract

A split-type annular magnetic body for noise control, which has been difficult to produce with Fe-based nanocrystalline alloys, is provided and obtains an excellent noise reduction effect. The annular magnetic body for noise control includes thin strips of soft magnetic metal laminated along a radial direction and is used by having a cable inserted therethrough. The annular magnetic body for noise control includes a plurality of split pieces divided into a non-annular shape and is used by placing split surfaces of the split pieces in contact with each other to form an annular shape. The product FL×Hc of the flatness FL of the split surfaces and the coercivity Hc of the split pieces is 7.0 μm·A/m or less. The flatness FL is the sum of absolute values of the maximum value and the minimum value of a cross-sectional curve measured in accordance with JIS B 0601:2001.

First claim

The invention claimed is:

1 . An annular magnetic body for noise control comprising thin strips of soft magnetic metal laminated along a radial direction, the annular magnetic body being used by having a cable inserted therethrough, wherein
the annular magnetic body for noise control comprises a plurality of split pieces divided into a non-annular shape and is used by placing split surfaces of the split pieces in contact with each other to form an annular shape, a product FL×Hc of a flatness FL of the split surfaces and a coercivity Hc of the split pieces is 7.0 μm·A/m or less, where the flatness FL is a sum of absolute values of a maximum value and a minimum value of a cross-sectional curve measured in accordance with JIS B 0601:2001, an arithmetic mean roughness Ra and a maximum height roughness Rz of the split surfaces satisfy Ra≤0.7 μm and Rz≤10 μm, respectively, a radial crushing strength is 50 MPa or more, the soft-magnetic metal strips include an Fe-based nanocrystalline alloy, and a surface pressure on the split surfaces is 0.05 MPa or more.

2 . The annular magnetic body for noise control according to claim 1 , wherein an impedance relative permeability μrz at a frequency of 100 kHz is 6000 or more.

3 . A member for noise control comprising:
the annular magnetic body for noise control according to claim 1 ; and a split-type core case in which subcases formed by dividing a cylinder into a non-annular shape are connected in an openable and closable manner to form a cylindrical shape, the subcases storing the split pieces of the annular magnetic body for noise control one by one, wherein when the split-type core case is closed, the split surfaces of the split pieces come in contact with each other inside the split-type core case to form the annular magnetic body for noise control.

Assignees

• Kk Riken

Inventors

• KAIMAI Nozomu
• Ishihara Daisuke
• HASHIMOTO Koushi

Classifications

• H01F17/06

  with core substantially closed in itself, e.g. toroid · CPC title

• H01F2017/065

  Core mounted around conductor to absorb noise, e.g. EMI filter · CPC title

• H01F1/16

  in the form of sheets (H01F1/147 takes precedence) · CPC title

• H05K9/0075

  Magnetic shielding materials · CPC title

• H01F27/245

  made from sheets, e.g. grain-oriented (H01F27/26 takes precedence) · CPC title