Electromagnetic actuator

• US 5,187,398 A
• Filed: 03/23/1992
• Issued: 02/16/1993
• Est. Priority Date: 08/31/1988
• Status: Expired due to Term

• Current Assignee: Aura Systems Inc.
• Original Assignee: Aura Systems Inc.
• Inventors: Bulgatz, Dennis C., Stuart, Keith O.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): JONES, JUDSON
• Application Number:
  US07/855,771
• Time in Patent Office: 330 Days
• Field of Search: 310/14, 310/30, 310/34, 310/35, 335/255, 335/256, 335/266, 335/279, 280/703, 280/707, 280/690, 280/840
• US Class Current: 310/14
• CPC Class Codes: B60G 17/0157 non-fluid unit, e.g. electric motor
• CPC Class Codes: B60G 2202/422 Linear motor
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2600/26 Electromagnets; Solenoids
• CPC Class Codes: H01F 2007/1692 Electromagnets or actuators with two coils
• CPC Class Codes: H01F 7/1615 Armatures or stationary parts of magnetic circuit having permanent magnet
• CPC Class Codes: H02K 1/17 Stator cores with permanent magnets
• CPC Class Codes: H02K 41/035 DC motors; Unipolar motors
• CPC Class Codes: H02K 41/0352 Unipolar motors
• CPC Class Codes: H02K 41/0354 Lorentz force motors, e.g. voice coil motors
• CPC Class Codes: H02K 41/0356 moving along a straight path

Abstract

An electromagnetic actuator includes a magnetic flux conductive material case, an electrical current conductive coil, a magnetic flux conductive material core, and a pair of radially polarized magnetic flux developing elements. The coil is disposed in the case coextensively adjacent to its interior wall. The core is movably received within the chamber with motion of the core occurring between the first end and the second end of the case such that a first region of the core traverses the coil between its first end and its midpoint, and a second region of the core traverses the coil between its second end and its midpoint. A first one of the magnetic elements is carried by the first region and a second one of the magnetic elements is carried by the second region so that magnetic flux across the coil between the first region and the case is in a first direction, and magnetic flux across the coil between the second region and the case is in a second direction. The coil is arranged so that an electrical current in the coil between the first coil and the midpoint flows in an opposite direction with respect to the direction of the current in the coil between the second coil and the midpoint. Therefore, the flux current cross product of the flux in the first direction with the coil current and the flux current cross product of the flux in the second direction with the coil current are additive.

Claims

1. An electromagnetic actuator comprising:

a magnetic flux conductive material case having a first case end, a second case end, and an interior wall extending between said first case end and said second case end, and a chamber confined by said interior wall;

an electrical current conductive coil disposed in said chamber coextensively adjacent said wall, said coil having a first coil end disposed proximate said first case end, the second coil end disposed proximate said second case end, and a midpoint;

a magnetic flux conductive material core having a first core end, a second core end, and an exterior wall extending between said first core end and said second core end, said exterior wall having a first region adjacent said first core end and a second region spaced from said first region adjacent said second core end, said core being movably received in said chamber with motion of said core occurring between said first case end and said second case end such that said first region traverses said coil between said first coil end and said midpoint and said second region traverses said coil between said second coil end and said midpoint, said coil and said exterior wall being in a facing relationship with respect to each other;

a pair of magnetic elements, each of said elements having a first magnetic pole face of a first polarity and second magnetic pole face of a second polarity opposite said first polarity, a first one of said magnetic elements being carried by said first region with said first pole face thereof being adjacent said first region and said second pole face thereof being distal said first region in a spaced relationship to said coil, a second one of said magnetic elements being carried by said second region with said first pole face thereof being distal said second region in a spaced relationship to said coil and said second pole face thereof being adjacent said second region so that magnetic flux across said coil between said first region and said interior wall is in a first direction and magnetic flux across said coil between said second region and said interior wall is in a second direction opposite said first direction, said coil being arranged so that an electrical current in said coil between said first coil end and said midpoint flows in an opposite direction with respect to the direction of said current and said coil between said second coil end and said midpoint whereby the flux current cross products of said flux in said first direction with said current and the flux current cross products of said flux in said second direction in said current are additive.

2. An electromagnetic actuator is set forth in claim 1 wherein each of said magnetic elements include a plurality of flat permanent magnets disposed edge to edge on each respective one of said first region and said second region.

3. An electromagnetic actuator is set forth in claim 1 wherein said coil is continuously wound from said first coil end to said second coil end and includes a current input at said midpoint at a commonly connected current return at each of said first coil end and said second coil end.

4. An electromagnetic actuator is set forth in claim 1 wherein said coil is wound in a first direction between said first coil end and said midpoint, and counterwound in a second direction between said midpoint and said second coil end, and includes a current input at said first coil end and a current return at said second coil end.

5. An electromagnetic actuator is set forth in claim 1 wherein said actuator further comprises an eddy current suppression laminate disposed intermediate said interior wall and said coil.

6. An electromagnetic actuator is set forth in claim 1 wherein said coil is of edge wound construction.

7. An electromagnetic actuator comprising:

a cylindrical magnetic flux conductive material case having a first case end, a second case end, and a cylindrical interior wall extending between said first case end and said second case end, and a chamber confined by said interior wall;

an electrical current conductive coil coaxially disposed in said chamber coextensively adjacent said wall, said coil having a first coil end disposed proximate said first case end, the second coil end disposed proximate said second case end, and a midpoint;

a cylindrical magnetic flux conductive material core having a first core end, a second core end, and a cylindrical exterior wall extending between said first core end and said second core end, said exterior wall having a first region adjacent said first core end and a second region spaced from said first region adjacent said second core end, said core being movably received coaxially in said chamber with motion of said core occurring between said first case end and said second case end such that said first region traverses said coil between said first coil end and said midpoint and said second region traverses said coil between said second coil end and said midpoint, said coil and said exterior wall being in a facing relationship with respect to each other;

a pair of radially polarized magnetic elements, each of said elements having a first magnetic pole face of a first polarity and second magnetic pole face of a second polarity opposite said first polarity, a first one of said magnetic elements being carried by said first region with said first pole face thereof being adjacent said first region and said second pole face thereof being distal said first region in a spaced relationship to said coil, a second one of said magnetic elements being carried by said second region with said first pole face thereof being distal said second region in a spaced relationship to said coil and said second pole face thereof being adjacent said second region so that magnetic flux across said coil between said first region and said interior wall is in a first direction and magnetic flux across said coil between said second region and said interior wall is in a second direction opposite said first direction, said coil being arranged so that an electrical current in said coil between said first coil end and said midpoint flows in an opposite direction with respect to the direction of said current and said coil between said second coil end and said midpoint whereby the flux current cross products of said flux in said first direction with said current and the flux current cross products of said flux in said second direction in said current are additive.

8. An electromagnetic actuator is set forth in claim 7 wherein each of said magnetic elements include a plurality of flat permanent magnets disposed edge to edge on each respective one of said first region and said second region.

9. An electromagnetic actuator is set forth in claim 7 wherein said coil is continuously wound from said first coil end to said second coil end and includes a current input at said midpoint at a commonly connected current return at each of said first coil end and said second coil end.

10. An electromagnetic actuator is set forth in claim 7 wherein said coil is wound in a first direction between said first coil end and said midpoint, and counterwound in a second direction between said midpoint and said second coil end, and includes a current input at said first coil end and a current return at said second coil end.

11. An electromagnetic actuator is set forth in claim 7 wherein said actuator further comprises an eddy current suppression laminate disposed intermediate said interior wall and said coil.

12. An electromagnetic actuator is set forth in claim 7 wherein said coil is of edge wound construction.