Sealed actuator

• US RE39,748 E1
• Filed: 06/22/2001
• Issued: 07/31/2007
• Est. Priority Date: 12/28/1995
• Status: Expired due to Term

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: Watanabe, Hayao, Horikoshi, Atsushi
• Primary Examiner(s): TAMAI, KARL I
• Application Number:
  US09/885,942
• Time in Patent Office: 2,230 Days
• Field of Search: 310/86, 310/87, 310/88, 310/89, 310/68.B, 310/112, 310/114
• US Class Current: 310/88
• CPC Class Codes: N/A

Abstract

A sealed actuator includes a motor stator having rotation-drive magnetic poles; a motor rotor arranged so as to confront magnetic pole surfaces of the motor stator while interposing a small distance therebetween and rotatably supported through roller bearings; and displacement detecting means for measuring displacement of the motor rotor. A partition wall made of a nonmagnetic metal is disposed in a clearance between the motor stator and the motor rotor, so that the inner space where the motor stator is disposed is hermetically covered. The bearings are disposed at both sides of the partition wall in the axial direction so that the load applied to the bearings are directly received by a housing. At least a part of the partition wall is reinforced by reinforcing members and a mold agent is charged into the space on the motor stator side.

Claims

1. A sealed actuator comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

housings to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

displacement measuring means for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space wherein said motor stator is disposed;

wherein said bearings are a plurality of rolling bearings, said rolling bearings supporting said motor rotor at positions on said housings at both sides of a member constituting said sealing partition wall in a longitudinal direction of said motor rotor so that said housings directly receive a load applied to said bearings,

wherein said displacement measuring means comprises a resolver rotor made of a mass of magnetic metal material, disposed at a side of said motor rotor, and includes a salient tooth cut from said mass of magnetic metal material; and

a resolver stator including a detection coil magnetic pole and disposed at a side of said motor stator.

2. A sealed actuator as claimed in claim 1, wherein said resolver rotor is fixed to a member of a nonmagnetic substance.

3. A sealed actuator as claimed in claim 1, wherein said resolver stator includes a differential circuit type winding.

4. A sealed actuator as claimed in claim 1, further comprising a magnetic shield plate made of a magnetic metal material disposed between said stator magnetic pole of said motor stator and said detection coil magnetic pole of said resolver stator.

5. A sealed actuator as claimed in claim 1, wherein said resolver rotor is fixed to a member of a nonmagnetic substance;

wherein said resolver rotor includes a differential circuit type winding; and

wherein said actuator further comprises a magnetic shield plate made of a magnetic metal material disposed between said stator magnetic pole of said motor stator and said detection coil magnetic pole of said resolver stator.

6. A sealed actuator comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

displacement measuring means for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space wherein said motor stator is disposed;

wherein said displacement measuring means comprises a resolver rotor made of a mass of magnetic metal material, disposed at a side of said motor rotor, and includes a salient tooth cut from said mass of magnetic metal material; and

a resolver stator including a detection coil magnetic pole and disposed at a side of said motor stator.

7. A sealed actuator as claimed in claim 6, wherein said resolver rotor is fixed to a member of a nonmagnetic substance.

8. A sealed actuator as claimed in claim 6, wherein said resolver stator includes a differential circuit type winding.

9. A sealed actuator as claimed in claim 6, wherein said displacement measuring means includes a coarse resolver and a fine resolver configured such that it is unnecessary to return to an origin to detect the position of the motor rotor.

10. A sealed actuator as claimed in claim 6, wherein said motor stator and said motor rotor constitutes a variable-reluctance motor.

11. A sealed actuator as claimed in claim 6, further comprising a magnetic shield plate made of a magnetic metal material disposed between said stator magnetic pole of said motor stator and said detection coil magnetic pole of said resolver stator.

12. A sealed actuator as claimed in claim 6, wherein said resolver rotor is fixed to a member of a nonmagnetic substance;

wherein said resolver rotor includes a differential circuit type winding; and

wherein said actuator further comprises a magnetic shield plate made of a magnetic metal material disposed between said stator magnetic pole of said motor stator and said detection coil magnetic pole of said resolver stator.

13. A sealed actuator comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

displacement measuring means for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space where said motor stator is disposed;

wherein said sealed actuator further comprises reinforcing means for reinforcing at least a part of said hermetically sealing partition wall, said reinforcing means being made of substantially the same nonmagnetic metal material as said partition wall.

14. A sealed actuator as claimed in claim 13, wherein said reinforcing means is at least one selected from a group consisting of a reinforcing member and a molding agent.

15. A sealed actuator comprising a plurality of unit sealed actuators connected in series to each other, each of said unit sealed actuators comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

displacement measuring means for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space where said motor stator is disposed;

wherein said bearings are a plurality of rolling bearings, said rolling bearings supporting said motor rotor at positions on said housings at both sides of a member constituting said sealing partition wall in a longitudinal direction of said motor rotor so that said housings directly receive a load applied to said bearings;

wherein said rotor magnetic pole includes a salient pole tooth of a steel material of a magnetic substance subjected to salient pole working; and

wherein said displacement measuring means comprises a resolver rotor made of a magnetic metal material, disposed at a side of said motor rotor, and include a salient pole tooth; and

a resolver stator including a detection coil magnetic pole and disposed at a side of said motor stator.

24. A sealed actuator as claimed in one of claims 15 to 22, wherein said rotation shaft of said motor rotor is an extension shaft fixed to said motor rotor.

16. A sealed actuator comprising a plurality of unit sealed actuators connected in series to each other, each of said unit sealed actuators comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

displacement measuring means for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space where said motor stator is disposed;

wherein said bearings are a plurality of rolling bearings, said rolling bearings supporting said motor rotor at positions on said housings at both sides of a member constituting said sealing partition wall in a longitudinal direction of said motor rotor so that said housings directly receive a load applied to said bearings.

17. A sealed actuator comprising a plurality of unit sealed actuators connected in series to each other, each of said unit sealed actuators comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

displacement measuring means for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space where said motor stator is disposed;

wherein said displacement measuring means comprises a resolver rotor made of a magnetic metal material, disposed at a side of said motor rotor, and including a salient tooth; and

a resolver stator including a detection coil magnetic pole and disposed at a side of said motor stator.

18. A sealed actuator as claimed in claim 17, wherein said resolver rotor is fixed to a member of a nonmagnetic substance.

19. A sealed actuator as claimed in claim 17, wherein said resolver stator includes a differential circuit type winding.

20. A sealed actuator as claimed in claim 17, wherein said displacement measuring means includes a coarse resolver and a fine resolver.

21. A sealed actuator as claimed in claim 17, wherein said motor stator and said motor rotor constitutes a variable-reluctance motor.

22. A sealed actuator as claimed in claim 17, further comprising a magnetic shield plate made of a magnetic metal material disposed between said stator magnetic pole of said motor stator and said detection coil magnetic pole of said resolver stator.

23. A sealed actuator as claimed in claim 17, wherein said resolver rotor is fixed to a member of a nonmagnetic substance;

wherein said resolver rotor includes a differential circuit type winding; and

wherein said actuator further comprises a magnetic shield plate made of a magnetic metal material disposed between said stator magnetic pole of said motor stator and said detection coil magnetic pole of said resolver stator.

25. A sealed actuator comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

an encoder for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space where said motor stator is disposed;

wherein said sealed actuator further comprises reinforcing means for reinforcing at least a part of said hermetically sealing partition wall, said reinforcing means being made of the same nonmagnetic metal material as said partition wall, wherein said partition wall is disposed between said reinforcing means and said motor rotor.

26. A sealed actuator as claimed in claim 25, wherein said encoder is an optical encoder.

27. A sealed actuator as claimed in claim 25, wherein said encoder is a magnetic encoder.

28. A sealed actuator comprising a plurality of unit sealed actuators connected in series to each other, each of said unit sealed actuators comprising:

a motor stator including a stator magnetic pole excited by a rotation-drive coil;

a housing to which said motor stator is attached;

a motor rotor including a rotor magnetic pole disposed opposite to a surface of said stator magnetic pole through a gap;

bearings for rotatably supporting a rotation shaft of said motor rotor to said housing;

an encoder for measuring displacement of said motor rotor; and

a hermetically sealing partition wall made of a nonmagnetic metal material and disposed at the gap between said stator magnetic pole and said rotor magnetic pole, a space where said motor rotor is disposed being hermetically isolated from a space where said motor stator is disposed;

wherein said bearings support said motor rotor at positions on said housing at both sides of a member constituting said sealing partition wall in a longitudinal direction of said motor rotor so that said housing directly receives a load applied to said bearings.

29. A sealed actuator as claimed in claim 28, wherein said encoder is an optical encoder.

30. A sealed actuator as claimed in claim 28, wherein said encoder is a magnetic encoder.