ELECTROMAGNETIC LINEAR MOTION DEVICE

• US 3,746,937 A
• Filed: 07/12/1971
• Issued: 07/17/1973
• Est. Priority Date: 07/12/1971
• Status: Expired due to Term

• Current Assignee: Hiroshi Koike
• Original Assignee: Hiroshi Koike
• Inventors: Koike, Hiroshi
• Primary Examiner(s): Duggan, D. F.
• Application Number:
  US05/161,706
• Time in Patent Office: 736 Days
• Field of Search: 310/12-14,27
• US Class Current: 318/122
• CPC Class Codes: H02K 35/04 with moving coil systems and stationary magnets
• CPC Class Codes: H02K 41/0356 moving along a straight path

Abstract

Herein disclosed is an electromagnetic linear motion device having an armature or movable core which is wrapped with a control coil cutting across a magnetic field established through a rectilinear air gap which is defined by inner and outer pole pieces having opposite polarities and positioned in parallel to and at least partly coextensive to each other. The device uses a support mechanism including bearings to longitudinally movably support the movable core and resilient suspension means which is adapted to have the movable core balanced in the longitudinal direction of the device. Such device can be used as a linear motor or a signal generator where minute and precise linear motions are required.

Claims

1. An electromechanical linear motion device comprising magnet means for establishing a magnetic field, an inner pole piece connected to one pole of said magnet means, an outer pole piece connected to the other pole of the magnet means and at least partly coextensive with said inner pole piece, the inner and outer pole pieces defining therebetween an elongated air gap through which said magnetic field passes, a movable core having a bore having at least one control coil wrapped therearound and longitudinally movable in said elongated air gap, said air gap having a length which is substantially greater than a length of strokes of said movable core in both directions, a plurality of guiding rods connected to said movable core and projecting outwardly of said inner and outer pole pieces and substantially in parallel to said air gap and to the direction of strokes of the movable core, a plurality of substantially equidistantly spaced bearings which are in rolling contact with said movable core and which are supported on shafts stationary relative to said inner and outer pole pieces, and spring means extending longitudinally through said movable core for biasing the movable core to a neutral position.

2. An electromagnetic linear motion device as set forth in claim 1, in which said bearings are grooved rollers which are in rolling contact with said guiding rods through their circumferential grooves.

3. An electromagnetic linear motion device as set forth in claim 1, in which said guiding rods are bored throughout their lenghts.

4. An electromagnetic linear motion device as set forth in claim 3, in which said control coil is led out of said device through at least one of the bored guiding rods.

5. An electromagnetic linear motion device as set forth in claim 1, in which said magnet means comprises a first pair of permanent magnet elements which are positioned between facing end portions of said inner and outer pole pieces and a second pair of permanent magnet elements which are positioned between the other end portions of said inner and outer pole pieces.

6. An electromagnetic linear motion device as set forth in claim 5, in which said outer pole piece consists of a pair of outer pole piece elements extending at spacings from and substantially in parallel to both sides of said inner pole piece.

7. An electromagnetic linear motion device as set forth in claim 1, in which said bearings are rotatably received in slots which are formed in said outer pole piece.

8. An electromagnetic linear motion device as set forth in claim 1, in which said bearings are rotatably received in recesses which are formed in an outer peripheral wall of said inner pole piece.

9. An electromagnetic linear motion device as set forth in claim 1, in which said spring is secured at one end to said movable core and at the other end to a member which is stationary

10. An electromagnetic linear motion device as set forth in claim 1, in which said resilient suspension means comprises a pair of springs, one of which is mounted between one end of said movable core and an end wall of a stationary member positioned opposite said outer pole piece and the other of which is mounted between the other end of said movable core and an end wall of said outer pole piece.

11. An electromagnetic linear motion device as set forth in claim 1, in which said resilient suspension means comprises a plurality of connecting rods extending from opposite ends of said movable core and projecting outwardly through both ends of said inner and outer pole pieces, a pair of end plates each connected to leading ends of said connecting rods, and a pair of springs each seated at one end on an outer face of each of said end plates and at the other end on stationary means which is stationary relative to said inner and outer pole pieces.

12. An electromagnetic linear motion device as set forth in claim 11, in which said connecting rods, said end plates, and said springs are made of an electrically conductive material and are electrically connected to said control coil.

13. An electromagnetic linear motion device as set forth in claim 11, in which said stationary means comprises adjusting bolt and nut for varying a prestress in each of said springs.

14. An electromagnetic linear motion device as set forth in claim 1, in which said magnet means comprises a permanent magnet.

15. An electromagnetic linear motion device as set forth in claim 14, in which said permanent magnet is positioned internally of said outer pole piece and substantially in line with said inner pole piece.

16. An electromagnetic linear motion device as set forth in claim 1, in which said magnet means comprises at least one magnetizing coil wrapped around said inner pole piece and located relative to said movable core, the magnetizing and control coils being wound in the same direction.

17. An electromagnetic linear motion device as set forth in claim 16, in which at least two magnetizing coils are wrapped around said inner pole piece, said magnetizing coils being connected in series with said control coil.

18. An electromagnetic linear motion device as set forth in claim 16, in which at least two magnetizing coils are wrapped around said inner pole piece, said magnetizing coils being connected in parallel to said control coil.

19. An electromagnetic linear motion device as set forth in claim 18, in which said magnetizing coils are connected in parallel to each other.

20. An electromagnetic linear motion device as set forth in claim 16, in which said magnetic means further comprises a rheostat which is connected in series with said control coil.

21. An electromagnetic linear motion device as set forth in claim 1, in whIch at least two control coils are wrapped around said movable core, said control coils being associated with respective brushes leading to conductors.