# US 9,752,898 B2 · Magnetic encoder and manufacturing method thereof

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- Number: US 9,752,898 B2
- Document ID: US9752898B2
- Status: Granted
- Kind: B2
- Application number: 14/707,305
- Filed: 2015-05-08
- Published: 2015-12-10
- Granted: 2017-09-05
- Earliest claimed: 2014-06-04
- Assignees: Nakanishi Metal Works Co., Ltd.
- Applicants: Nakanishi Metal Works Co., Ltd.
- Inventors: Masayuki Taki; Mitsuru Saitoh
- Web page: https://patentgrep.com/patent/US9752898B2

## CPC

- G01D 5/2006: {by influencing the self-induction of one or more coils (G01D5/22 takes precedence)}
- B29C 45/1418: {the inserts being deformed or preformed, e.g. by the injection pressure}
- B29C 45/1459: {Coating annular articles}
- F16C 41/007: {Encoders, e.g. parts with a plurality of alternating magnetic poles}
- G01D 5/2451: {Incremental encoders (G01D5/2454 takes precedence)}
- G01P 3/443: {mounted in bearings (bearings F16C)}
- G01P 3/487: delivered by rotating magnets
- B29K 2077/00: Use of {PA, i.e.} polyamides, e.g. polyesteramides {or derivatives thereof}, as moulding material
- B29K 2081/04: {Polysulfides, e.g. PPS, i.e. polyphenylene sulfide or derivatives thereof}
- B29K 2105/16: Fillers
- B29K 2505/12: Iron
- B29K 2995/0008: Magnetic or paramagnetic
- B29L 2031/752: {Measuring equipment}
- F16C 19/186: {with three raceways provided integrally on parts other than race rings, e.g. third generation hubs}
- F16C 33/723: {Shaft end sealing means, e.g. cup-shaped caps or covers}
- F16C 2326/02: Wheel hubs or castors
- G01D 2205/80: Manufacturing details of magnetic targets for magnetic encoders
- 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
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- 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})
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

An axial-type magnetic encoder includes an annular fixing member that is fabricated by press molding, and an annular plastic magnet that is attached by injection molding to a sensor-opposed surface of the annular fixing member. When the annular fixing member includes a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, the magnetic encoder has a high-form accuracy surface on the sensor-opposed surface more radially outward than a range of a diameter (d−2·r) determined by an inner diameter d of the cylindrical part and a radius r of a corner between the cylindrical part and the inward flange part. An outer diameter of the annular plastic magnet is positioned on the high-form accuracy surface.

## Claims

### Claim 1

An axial-type magnetic encoder, comprising:
an annular fixing member that has a cylindrical part attached to a rotating body and an inward flange part extended more radially inward than an end edge of the cylindrical part and is fabricated by press molding; and
an annular plastic magnet that is attached by injection molding to a sensor-opposed surface of the annular fixing member, wherein
when the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, the magnetic encoder has a high-form accuracy surface on the sensor-opposed surface more radially outward than a range of a diameter (d−2·r) determined by an inner diameter (d) of the cylindrical part and a radius (r) of a corner between the cylindrical part and the inward flange part, and
an outer diameter of the annular plastic magnet is positioned on the high-form accuracy surface.

### Claim 2 (depends on 1)

The magnetic encoder according to claim 1, wherein
the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, and
the high-form accuracy surface is formed on the sensor-opposed surface by performing a press process to press stepwise a back surface of the sensor-opposed surface.

### Claim 3 (depends on 1)

The magnetic encoder according to claim 1, wherein
the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, and
the high-form accuracy surface is formed on the sensor-opposed surface by performing a chamfering press process or stepwise press process to press by surface a round corner between the cylindrical part and the inward flange part.

### Claim 4 (depends on 1)

The magnetic encoder according to claim 1, wherein
the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, and
the high-form accuracy surface is formed on the sensor-opposed surface by performing a bead process on an annular blank in a concentric manner to form a ribbed portion and then performing a press process to squeeze an outer side of the ribbed portion to mold the annular fixing member, thereby to eliminate the round corner between the cylindrical part and the inward flange part.

### Claim 5 (depends on 1)

The magnetic encoder according to claim 1, wherein
the high-form accuracy surface is formed on the sensor-opposed surface by performing a press process on a member composed of a large-diameter cylindrical part larger in diameter than the cylindrical part and a large-diameter inward flange part extended radially inward from an end edge of the large-diameter cylindrical part to narrow the large-diameter cylindrical part, and then setting a radially outward portion of the large-diameter inward flange part as an outward projection projecting radially outward.

### Claim 6

A manufacturing method of an axial-type magnetic encoder, comprising:
a press molding step of fabricating by press molding an annular fixing member that has a cylindrical part attached to a rotating body and an inward flange part extended more radially inward than an end edge of the cylindrical part; and
an injection molding step of, while the annular fixing member is placed in an axial draw mold, injecting a dissolved annular plastic magnet material into the mold, wherein
the manufacturing method includes a step of, while the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, forming by a press process a high-form accuracy surface on a sensor-opposed surface more radially outward than a range of a diameter (d−2·r) determined by an inner diameter (d) of the cylindrical part and a radius (r) of a corner between the cylindrical part and the inward flange part, and
the injection molding step is performed in the state where the annular fixing member is placed in the mold such that a mold matching surface is positioned on the high-accuracy surface.

### Claim 7 (depends on 6)

The manufacturing method of a magnetic encoder according to claim 6, wherein
the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, and
the press process is a press process by which to press stepwise a back surface of the sensor-opposed surface.

### Claim 8 (depends on 6)

The manufacturing method of a magnetic encoder according to claim 6, wherein
the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, and
the press process is a chamfering press process or stepwise press process by which to press by surface a round corner between the cylindrical part and the inward flange part.

### Claim 9 (depends on 6)

The manufacturing method of a magnetic encoder according to claim 6, wherein
the annular fixing member is composed of a cylindrical part and an inward flange part extended radially inward from an end edge of the cylindrical part, and
the press process is a press process by which to subject an annular blank to a bead process in a concentric manner to form a ribbed portion and then squeeze an outer side of the ribbed portion.

### Claim 10 (depends on 6)

The manufacturing method of a magnetic encoder according to claim 6, wherein the press process is a press process performed on a member composed of a large-diameter cylindrical part larger in diameter than the cylindrical part and a large-diameter inward flange part extended radially inward from an end edge of the large-diameter cylindrical part to narrow the large-diameter cylindrical part and form the cylindrical part.