POSITION DETECTOR, SEAT BELT RETRACTOR HAVING THIS POSITION DETECTOR, AND SEAT BELT APPARATUS HAVING THIS SEAT BELT RETRACTOR

• US 20110278905A1
• Filed: 05/13/2011
• Published: 11/17/2011
• Est. Priority Date: 05/17/2010
• Status: Active Grant

• Current Assignee: Joyson Safety Systems Japan GK
• Original Assignee: Takata Corporation (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Ikeda, Kenji
• Granted Patent: US 9,333,941 B2
• Time in Patent Office: Days
• US Class Current: 297/475
• CPC Class Codes: B60R 22/34 Belt retractors, e.g. reels anchoring devices , e.g. guide loops , with means to tension the belt in an emergency B60R22/195
• CPC Class Codes: B60R 22/46 Reels with means to tension the belt in an emergency by forced winding upelectrical circuits for triggering safety arrangements B60R21/01 ; tensioners using reels only guiding the belt during normal use, e.g. splitted reels B60R22/195
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

A position detector is provided that can detect the position of a moving member with a higher degree of accuracy. In one form, a rotation sensor includes a magnet in which N-pole magnets and S-pole magnets are arranged alternately and circularly and that rotates in conjunction with the rotation of a spool, and first and second Hall elements and that are disposed apart from each other in the circumferential direction of the magnet and detect the poles of the N-pole magnets and S-pole magnets. In that case, the first and second Hall elements and are both unipolar detection type Hall elements that detect only the S-pole. The magnetization width of the S-pole magnets is set large, and the magnetization width of the N-pole magnets is set small.

Claims

1. A position detector comprising:

a magnetic member in which N-poles and S-poles are arranged alternately and that moves in conjunction with the movement of a moving member; and

at least one magnetic detecting member that detects only the N-poles or S-poles of the magnetic member,

wherein the position detector detects the position of the moving member by detecting only the N-poles or S-poles of the magnetic member using the at least one magnetic detecting member, and

the magnetization width of the N-poles or S-poles of the magnetic member detected by the at least one magnetic detecting member is larger than the magnetization width of the other poles.

2. The position detector according to claim 1,

wherein the moving member is a rotating member,

the N-poles and S-poles of the magnetic member are arranged alternately and circularly, and the magnetic member rotates about the center of the circular arrangement of the N-poles and S-poles in conjunction with the rotation of the rotating member, and

the at least one magnetic detecting members comprises a first magnetic detecting member and a second magnetic detecting member disposed apart from the first magnetic detecting member in the circumferential direction of the circular arrangement of the N-poles and S-poles.

3. The position detector according to claim 1 or 2,

wherein the magnetic member includes a predetermined number of magnets that are the N-pole magnets and S-pole magnets arranged alternately and circularly, and

the at least one magnetic detecting member is at least one Hall element that detects only the N-poles of the N-pole magnets or the S-poles of the S-pole magnets.

4. A seat belt retractor comprising at least:

a spool that retracts a seat belt;

a driving means for rotating this spool; and

a rotation amount detector that detects the rotation amount of the spool,

wherein the rotation amount of the spool is controlled by controlling the driving of the driving means on the basis of the rotation amount of the spool detected by the rotation amount detector,

the rotation amount detector is the position detector according to claim 3, and the moving member is the spool,

the rotation amount detector has a rotating disk, the rotating disk has the predetermined number of magnets arranged concentrically with the rotating disk, and a driven member that is rotatable integrally with the predetermined number of magnets,

the seat belt retractor has a driving member provided rotatably integrally with the spool and transmitting the rotation of the spool to the driven member,

the seat belt retractor has a speed increasing mechanism that increases the rotation speed of the driving member and transmits to the driven member, and accelerates the rotation of the spool and rotates the magnets, and

the seat belt retractor has a magnetic detecting member that detects, of the predetermined number of magnets, a magnet located at a predetermined position.

5. The seat belt retractor according to claim 4,

wherein the rotation amount detector is disposed eccentrically relative to the rotating shaft of the spool and in the radial direction of the rotating shaft,

the driven member is a driven gear, and the driving member is a driving gear meshing with the driven gear, and

the speed increasing mechanism includes the driven gear and the driving gear.

6. The seat belt retractor according to claim 4,

wherein the rotation amount detector is disposed eccentrically relative to the rotating shaft of the spool and in the radial direction of the rotating shaft,

the driven member is a driven pulley, and the driving member is a driving pulley, and

the speed increasing mechanism includes the driven pulley, the driving pulley, and an endless belt looped over the driven pulley and the driving pulley.

7. The seat belt retractor according to claim 4,

wherein the rotation amount detector is disposed concentrically with the rotating shaft of the spool, and

the speed increasing mechanism is a planetary gear mechanism.

8. The seat belt retractor according to claim 7,

wherein the driven member is a sun gear of the planetary gear mechanism, and

the driving member is a carrier of the planetary gear mechanism.

9. A seat belt apparatus comprising at least:

a seat belt retractor that retracts a seat belt;

a tongue that is slidably supported by the seat belt withdrawn from this seat belt retractor; and

a buckle with which the tongue is releasably engaged,

wherein the seat belt apparatus restrains an occupant with the seat belt, and

the seat belt retractor is the seat belt retractor according to any one of claims 4 to 8.