# US 12,216,138 B2 · Rotation speed detector

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- Number: US 12,216,138 B2
- Document ID: US12216138B2
- Status: Granted
- Kind: B2
- Application number: 18/707,180
- Filed: 2022-05-16
- Published: 2024-12-19
- Granted: 2025-02-04
- Earliest claimed: 2022-05-16
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Toshio Mekata; Takeshi Musha; Hitoshi Hasegawa; Takuya Noguchi
- Web page: https://patentgrep.com/patent/US12216138B2

## CPC

- G01P 3/44: for measuring angular speed (G01P3/56 takes precedence)
- G01D 5/245: using a variable number of pulses in a train
- G01P 3/481: of pulse signals
- G01P 3/4815: {using a pulse wire sensor, e.g. Wiegand wire}
- G01P 3/487: delivered by rotating magnets
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

A rotation speed detector includes: a base material to be attached to a rotating body; a first magnetic pole having an arcuate strip shape and provided on the base material; a second magnetic pole having an arcuate strip shape and provided on the base material; and a power generation element including a magnetic wire configured to cause a large Barkhausen effect, and a pickup coil. The power generation element is arranged to face the first magnetic pole and the second magnetic pole so that a longitudinal direction of the magnetic wire is provided along a radial direction of the first magnetic pole and the second magnetic pole. A non-magnetic gap is provided between the first magnetic pole and the second magnetic pole.

## Claims

### Claim 1

A rotation speed detector comprising:
a non-magnetic base material to be attached to a rotating body;
a first magnetic pole having an arcuate strip shape and provided on the base material such that an outer peripheral side serves as an N pole and an inner peripheral side serves as an S pole;
a second magnetic pole having an arcuate strip shape and provided on the base material such that an outer peripheral side serves as the S pole and an inner peripheral side serves as the N pole; and
a power generation element including, a magnetic wire configured to cause a large Barkhausen effect, and a pickup coil configured to detect magnetization reversal of the magnetic wire, wherein
the power generation element is arranged to face the first magnetic pole and the second magnetic pole so that a longitudinal direction of the magnetic wire is provided along a radial direction of the first magnetic pole and the second magnetic pole, and
a non-magnetic gap is provided between the first magnetic pole and the second magnetic pole, wherein
each of the first magnetic pole and the second magnetic pole includes a plurality of bar magnets, and
an installation interval of the plurality of bar magnets included in the first magnetic pole and the second magnetic pole is equal to or less than a half of a half bandwidth, wherein
the half bandwidth is a dimension in a direction parallel to a surface of the base material on which the first magnetic pole and the second magnetic pole are provided and orthogonal to a longitudinal direction of the bar magnet and is a dimension of a range in which a magnetic field generated by the bar magnet is equal to or more than a half of a peak.

### Claim 2 (depends on 1)

The rotation speed detector according to claim 1, wherein
the gap is larger than a vibration width in a rotation direction generated in the rotating body.