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'The following images were taken from Patent No. 6342746'

Patent Text

'The following text was taken from Patent No. 6342746'

Reference is made to FIGS. 11A-11F which depict

devices similar to that of FIGS. 5-6 except that a bypass,

formed of magnetic material, is provided in each case. In

device 220 of FIGS. 11A-11C a bypass 222 is provided from

pole piece 224 to pole piece 226 and is located between

permanent magnet 228 and control coils 230, 232, with

armature 234 located adjacent the ends of pole pieces 224,

226. In FIG. 11A with no coil energization, magnet flux

components 236 and 237 travel as shown. When coils 230

and 232 are energized in an aiding or adding manner as in

FIG. 11B, the result is permanent magnet magnetic flux

components 236 and 237 traveling as shown, and with the

added magnetic flux component 238 from coils 230 and 232

also traveling as shown. Thus, in device 220 energizing the

coils in an aiding manner results in an increased magnetic

coupling force on armature 234. In FIG. 11C coils 230,232

are energized in an opposing exceeding manner which

results in permanent magnetic flux components 236 and 237

traveling as shown and excess magnetic flux component 238

traveling as shown. Thus, in device 220 energizing the coils

in an opposing exceeding manner results in magnetic coupling

force on armature 234, albeit smaller than that in the

aiding exceeding case.

In device 240 of FIGS. 11D-11F a bypass 242 is provided

between pole piece 244 and pole piece 246 but is located on

an opposite side of permanent magnet 248 as compared to

control coils 250, 252 and armature 254. Permanent magnet

flux components 256 and 257 are shown for no coil energization

in FIG. 11D. In FIG. 11E the paths of permanent

magnet flux components 256 and 257, as well as excess coil

magnetic flux 258, are shown when coils 250, 252 are

energized in an aiding exceeding manner. In FIG. 11F the

path of each magnetic flux component 256, 257, and 258 is

shown when coils 230, 232 are energized in an opposed

exceeding manner.

FIGS. 12A-12E depict a device 270 similar to that shown

in FIGS. 7-9 except that bypasses 272 and 274 are provided

from pole piece 276 to pole piece 278. Bypass 272 is located

between permanent magnet 280 and control coils 282, 284

and bypass 274 is located between permanent magnet 280

and control coils 286, 288. Armatures 290 and 292 are also

provided. When no coils are energized permanent magnet

magnetic flux components 294, 296, 298, and 300 travel as

shown in FIG. 12A.

If coils 282, 284 are energized in an opposing manner

permanent magnet flux components 295, 297, and 299 travel

as shown, with no flux component traversing the path which

includes armature 290 and therefore no magnetic coupling

force acting thereon. This would be the case for when coils

282, 284 are energized to the level where the coils magnetic

flux just blocks, but does not exceed, the magnetic flux

component 294 (FIG. 12A) from permanent magnet 280. If,

however, coils 282, 284 are energized in an opposed exceeding

manner an excess coil magnetic flux component 301 is

produced which travels a path including armature 290 and

bypass 272 results as shown in FIG. 12C.

Coils 286, 288 may be energized in an aiding manner such

that all permanent magnet magnetic flux travels along the

path which includes armature 292 as shown in FIG. 12D. If

coils 286, 288 are energized in excess of the level of FIG.

12D then the excess magnetic flux component 304 traverses

the path which includes armature 292 and bypass 274 as

shown in FIG. 12E, thereby increasing the magnetic coupling

force on armature 292 as compared to FIG. 12D. The

advantage of incorporating such bypasses into permanent

magnet control components in certain applications will

become apparent below.