Small-size direct-acting actuator

• US 20050121984A1
• Filed: 12/07/2004
• Published: 06/09/2005
• Est. Priority Date: 12/08/2003
• Status: Active Grant

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Minowa, Takehisa, Nakamura, Hajime
• Granted Patent: US 7,355,305 B2
• Time in Patent Office: Days
• US Class Current: 310/12.30
• CPC Class Codes: H01F 2007/068 using printed circuit coils
• CPC Class Codes: H01F 7/122 by permanent magnets H01F7/1615, H01F7/1646 take precedence
• CPC Class Codes: H01F 7/14 Pivoting armatures H01F7/17 takes precedence
• CPC Class Codes: H02K 33/06 with polarised armatures

Abstract

A direct-acting actuator is provided comprising a stator section (16), an attachment section (6) secured to the stator section, micro-beams (8, 10) extending from the attachment section, a rotor section (12) supported for swing motion by the micro-beams, a permanent magnet (18) disposed in the stator section, and a coil (4) disposed in the rotor section. Electric current is conducted through the coil in the magnetic field created by the permanent magnet for causing the micro-beams to be displaced for inducing swing motion of the rotor section. The actuator can be assembled to a small size, typically a width of 1-10 mm, a length of 1-10 mm, and a height of 0.1-5 mm.

Claims

1. A small-size direct-acting actuator having a width of 1 to 10 mm, a length of 1 to 10 mm, and a height of 0.1 to 5 mm, comprising

a stator section,

an attachment section secured to the stator section,

metallic micro-beams extending from the attachment section and shaped by bending,

a rotor section supported for swing motion by the micro-beams,

a permanent magnet disposed in the stator or rotor section, and

a coil disposed in the rotor or stator section,

wherein electric current is conducted through the coil in the magnetic field created by the permanent magnet for causing the micro-beams to be displaced for inducing swing motion of the rotor section.

2. The actuator of claim 1, wherein a pair of said micro-beams are disposed at opposite sides of the stator section for supporting the rotor section, and said micro-beams are flexible enough to be displaced by a drive force developed between the stator and rotor sections in a drive direction which is parallel to a plane sandwiched between the pair of micro-beams and perpendicular to the longitudinal direction of the micro-beams, but highly stiff in other directions.

3. The actuator of claim 1, wherein each said micro-beam includes at least one fold.

4. The actuator of claim 1, wherein said micro-beams are formed integrally with the attachment section and the rotor section by punching and bending a metal plate having a gage of 0.025 to 0.5 mm.

5. The actuator of claim 1, wherein said stator section is made of a ferromagnetic material.

6. The actuator of claim 1, wherein said rotor section is made of a ferromagnetic material.

7. The actuator of claim 1, further comprising an auxiliary yoke opposed to said stator section for forming a magnetic circuit, with said rotor section being interposed between the auxiliary yoke and said stator section.

8. A small-size direct-acting actuator having a width of 1 to 10 mm, a length of 1 to 10 mm, and a height of 0.1 to 5 mm, comprising

a stator section where a permanent magnet or a coil is disposed, and

a member comprising a stator attachment section, micro-beams, and a rotor section where a coil or a permanent magnet is disposed,

the permanent magnet and the stator section forming a magnetic circuit, the permanent magnet and the coil being opposed to define a small gap therebetween and within the magnetic circuit, and

the micro-beams being juxtaposed and integrally formed at laterally opposed edges of the stator attachment section and stand along the edges at right angles toward the stator section so that the micro-beams are formed by furnishing elongated strips extending forward from the front side of the stator attachment section at opposed edges, folding the strips inside an angle of 180°

to form a first fold, then folding the strips inside an angle of 180°

at a position backward of the attachment section front side to form a second fold or in the reverse direction to the first fold and provide the last portions of the strips which extend forward again, and the rotor section is integrally formed through transition portions with the last forward extending portions of the strips,

wherein when electricity is conducted across the coil in the magnetic field created by the permanent magnet, the rotor section is arcuately moved by Lorentz forces in a latered direction.

9. The actuator of claim 8, wherein the member including the stator attachment section, micro-beams and rotor section is prepared by furnishing a blank in which the attachment section and the rotor section are bridged at laterally opposed sides by strips, folding inside the strips at a first intermediate point an angle of about 180°

so that the rotor section overlies the attachment section, then folding back the strips at a second intermediate point an angle of about 180°

so that the rear edge of the rotor section is situated close to the front edge of the attachment section, and finally folding the strips along their longitudinal inner side at right angles toward the stator section.