Rotation number detector

Patent metadata

Field	Value
Publication number	US-9664535-B2
Application number	US-201314655837-A
Country	US
Kind code	B2
Filing date	Feb 22, 2013
Priority date	Feb 22, 2013
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

A rotation number detector according to an embodiment is a rotation number detector that detects the number of rotations of a magnet attached to a rotating body by using a power generation unit. The power generation unit includes N (N is a natural number equal to or larger than 1) power generation elements, each including a magnetic wire in which magnetization reversal occurs due to a large Barkhausen effect and a pickup coil that is wound around the magnetic wire. The magnetic wire is longer than a wound portion of the pickup coil in an extension direction of the magnetic wire of the power generation elements. The magnetic wire is set above a rotation center of the magnet.

First claim

The invention claimed is:

1. A rotation number detector that detects a number of rotations of a magnet attached to a rotating body by using a power generation unit, wherein
the power generation unit includes N power generation elements, each including a magnetic wire, in which magnetization reversal occurs due to a large Barkhausen effect, and a pickup coil that is wound around the magnetic wire, N being a natural number equal to or larger than 1,
the magnetic wire provided in each of the power generation elements is longer than a wound portion of the pickup coil in an extension direction of the magnetic wire,
the pickup coil provided in each of the power generation elements has two wound portions
that are separated from each other by a distance larger than an outer diameter of the pickup coil and
that are connected in series to each other, and

the magnetic wire provided in each of the power generation elements is provided above a rotation center of the magnet.

2. The rotation number detector according to claim 1 , wherein
N is a natural number equal to or larger than 2, and
portions of each of the magnetic wires about which the pickup coils of the N power generation elements are not wound overlap with each other above the rotation center.

3. The rotation number detector according to claim 1 , wherein
the distance between the two wound portions provided in each of the power generation elements is set such that a time difference between times at which the two wound portions respectively detect the magnetization reversal becomes a desired value, and is set based on magnetization reversal velocity and magnetic-reversal generating points of each of the magnetic wires provided in each of the power generation elements.

4. The rotation number detector according to claim 1 , wherein the magnet has a disc shape and is radially magnetized with one S pole and one N pole or double-sided four-pole magnetized with two S poles and two N poles, each set of poles on each side.

5. A rotation number detector that detects a number of rotations of a magnet attached to a rotating body by using a power generation unit, wherein
the power generation unit includes N power generation elements, each including a magnetic wire, in which magnetization reversal occurs due to a large Barkhausen effect, and a pickup coil that is wound around the magnetic wire, N being a natural number equal to or larger than 2,
the magnetic wire provided in each of the power generation elements is longer than a wound portion of the pickup coil in an extension direction of the magnetic wire,
the pickup coil provided in each of the power generation elements has two wound portions
that are separated from each other by a distance larger than an outer diameter of the pickup coil and
that are connected in series to each other, and

portions of each of the magnetic wires about which the pickup coils of the N power generation elements are not wound overlap with each other.

6. The rotation number detector according to claim 5 , wherein
the distance between the two wound portions provided in each of the power generation elements is set such that a time difference between times at which the two wound portions respectively detect the magnetization reversal becomes a desired value, and is set based on magnetization reversal velocity and magnetic-reversal generating points of each of the magnetic wires provided in each of the power generation elements.

7. The rotation number detector according to claim 5 , wherein
the magnet has a disc shape and is radially magnetized with one S pole and one N pole or double-sided four-pole magnetized with two S poles and two N poles, each set of poles on each side.

Assignees

• Tatei Yoshinao
• Musha Takeshi
• Nakajima Hajime
• Okamuro Takashi
• Nimura Masanori
• Mitsubishi Electric Corp

Inventors

• Tatei Yoshinao
• Musha Takeshi
• Nakajima Hajime
• Okamuro Takashi
• Nimura Masanori

Classifications

• G01P3/4815 Primary

  using a pulse wire sensor, e.g. Wiegand wire · CPC title

• G01D5/145

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title

• G01D5/244 Primary

  influencing characteristics of pulses or pulse trains; generating pulses or pulse trains · CPC title

• G01D5/2006

  by influencing the self-induction of one or more coils (G01D5/22 takes precedence) · CPC title