Moving magnet motors

Patent metadata

Field	Value
Publication number	US-9763013-B2
Application number	US-201414766317-A
Country	US
Kind code	B2
Filing date	Mar 7, 2014
Priority date	Mar 15, 2013
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

An apparatus includes a load, a lever that is coupled to the load, and an electric motor that is coupled to the lever for driving the lever in oscillatory, rotary motion about a pivot axis. The electric motor includes an armature and a stator. The armature is coupled to the lever and includes a permanent magnet. The stator defines an air gap within which the armature is disposed. The stator is configured for creating magnetic flux across the air gap for the permanent magnet to interact with, thereby to drive motion of the load. The electric motor is configured such that substantially no detent forces (a/k/a cogging forces) are generated between the stator and the permanent magnet as the lever is driven by the motor.

First claim

What is claimed is:

1. An apparatus comprising:
I.) a load;
II.) a lever coupled to the load; and
III.) an electric motor coupled to the lever for driving the lever in oscillatory, rotary motion about a pivot axis, the electric motor comprising:
A.) an armature comprising a permanent magnet, the armature being coupled to the lever; and
B.) a stator defining an air gap within which the armature is disposed, the stator being configured for creating magnetic flux across the air gap for the permanent magnet to interact with, thereby to drive motion of the load,

wherein the electric motor is configured such that substantially no detent forces are generated between the stator and the permanent magnet as the lever is driven by the motor, wherein the stator is configured to generate magnetic flux which passes across the air gap in two opposing directions at the same time.

2. The apparatus of claim 1 , wherein the stator defines:
a first pole including a first pair of opposed pole faces, and
a second pole including a second pair of opposed pole faces, and
wherein the air gap separates the first pair of opposed pole faces, and the gap separates the second pair of opposed pole faces.

3. The apparatus of claim 2 , wherein the stator is configured to generate magnetic flux which passes in a first one of the two opposing directions between the first pair opposed pole faces, while, at the same time, passing in a second one of the two opposing directions, opposite the first one of the two opposing directions, between the second pair of opposed pole faces.

4. The apparatus of claim 1 , wherein the stator comprises:
a pair of cores of high magnetic permeability material, the cores together defining:
a first pole;
a second pole; and
an air gap within which the permanent magnet is suspended; and

a pair of coils, each coil wrapped around one of the cores for carrying current to generate magnetic flux across the air gap for the permanent magnet to interact with.

5. The apparatus of claim 1 , wherein the lever is coupled to the load such that oscillatory, rotary motion of the lever moves the load in a pistonic motion.

6. The apparatus of claim 1 , wherein the apparatus is a loudspeaker, and wherein the load is an acoustic diaphragm.

7. The apparatus of claim 6 , wherein the loudspeaker has a sealed box construction.

8. The apparatus of claim 6 , wherein the lever is coupled to the acoustic diaphragm such that oscillatory, rotary motion of the lever moves the acoustic diaphragm in a pistonic motion.

9. A loudspeaker comprising:
I.) an acoustic diaphragm; and
II.) an electric motor coupled to the acoustic diaphragm for driving motion of the acoustic diaphragm, the electric motor comprising:
A.) a stator comprising:
i.) a pair of cores of high magnetic permeability material, the cores together defining:
a.) a first pole,
b.) a second pole, and
c.) an air gap separating opposed faces of the first and second poles;

ii.) a pair of coils, each coil wrapped around one of the cores for carrying current to generate magnetic flux across the air gap; and

B.) an armature comprising a single permanent magnet, the armature disposed within the air gap in non-contacting relationship with the stator and supported to allow the permanent magnet to interact with magnet flux in the air gap for moving the armature between the first and second poles, wherein the stator is configured to generate magnetic flux which passes across the air gap in two opposing directions at the same time.

10. The loudspeaker of claim 9 , wherein the stator is configured to generate magnetic flux which passes in a first one of the two opposing directions between opposed pole faces of the first pole, while, at the same time, passing in a second one of the two opposing directions, opposite the first one of the two opposing directions, between opposed pole faces of the second pole.

11. The loudspeaker of claim 9 , wherein the stator is configured to generate magnetic flux across the air gap such that the permanent magnet is attracted to one of the first and second poles and is repelled by the other one of the first and second poles.

Assignees

• Bose Corp

Inventors

• Lucas Brian M
• Isaksson Johan H

Classifications

• H04R11/02 Primary

  Loudspeakers · CPC title

• H04R9/04

  Construction, mounting, or centering of coil · CPC title

• H04R2400/07

  Suspension between moving magnetic core and housing · CPC title

• H02K16/00

  Machines with more than one rotor or stator {(machines for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts H02K51/00; permanent magnet machines with multiple rotors or stators relatively rotated for vectorially combining the excitation fields or the armature voltages H02K21/029)} · CPC title

• H04R9/027

  Air gaps using a magnetic fluid · CPC title