D.C. motor with axially disposed working flux gap

A p.m. d.c. motor in which a stator is structured as a magnetically permeable base upon which stator pole components are mounted in upstanding fashion. Each of the stator pole components is formed as a laminar core of elongate rectangular shape about which a plastic bobbin is slideably positioned. The field windings of the stator are wound about this bobbin to provide a structure having no flared tips or the like and wherein winding can take place on bobbins separately from the stator structure. A disk-shaped rotor carrying a sequence of flat permanent magnets is positioned over the tips of the stator components and is rotatably driven by select energization of the latter. Select skewing of the stator poles and design of the geometry of the permanent magnets functions to significantly reduce detent torque phenomena.

BACKGROUND 
Investigators involved in modern electronic and electro-mechanical 
industries increasingly have sought more refined and efficient devices and 
techniques in the generation of motion and the effectuation of its 
control. For example, the mass storage of data for computer installations 
is carried out by recordation on magnetic disks which are rotatably driven 
under exacting specifications. The speed of data handling performance of 
these computation systems is very much dependent upon the available speed 
of recording and retrieval from the surfaces of the disks. Similar 
requirements of performance are to be observed in the fields of robotics, 
machine tools and the like. 
In the past, pneumatic and hydraulic movers were resorted to for a great 
many of the latter applications. However, a significant trend to 
electrically powered devices has occurred because of their inherently 
faster and more reliable motion control. Such control capability has 
greatly expanded with the emergence of the microprocessor on a significant 
scale. 
Permanent magnet (P.M.) direct current (d.c.) motors represent the largest 
and most cost effective portion of the current electrical motor market. 
These motors occur in a wide variety of designs. 
Generally, the classic P.M. d.c. motor is a three-phase device having a 
stator functioning to mount two or more permanent magnet poles which 
perform in conjunction with three of more rotor mounted field windings 
which are wound over the inward portions of pole structures typically 
formed of laminated steel sheets. The ends or tip portions of the rotor 
poles are flared or curved somewhat broadly to improve their magnetic 
interaction with the stator magnets. Typically, field windings are 
intercoupled in either a delta or Y circuit configuration and by exciting 
them in a particular sequence, an electromagnetic field, in effect, is 
caused to move from one flared pole tip to the next to achieve an 
interaction with the permanent magnets and evolve rotational motion. This 
interaction occurs in almost all designs through an air gap which is 
disposed "radially" to the motor shaft between the stator and rotor in 
parallel relationship with the axis of the rotor, i.e. a "radial gap" is 
provided. The interaction between the permanent magnet field and the field 
of the excited windings is one wherein force vectors are developed in 
consequence of an association of the exciting field with the field or flux 
sense of the magnets. Where typical ferrite or alnico type permanent 
magnets are used, any other disposition of the field interaction would 
effect a destructive demagnetization of these magnets. Classically, the 
switching providing select excitation of the field windings is provided by 
a commutator rotating with the rotor and associated with brushes 
representing a make and break mechanical switching device functioning to 
move the field along the pole tips. 
As the classic P.M. d.c. motor has been applied to more sophisticated 
electromechanical systems, it has been found to be dificient in many 
aspects. For example, the make and break commutation is electrically 
noisy, a condition which in many applications will be found to be 
unacceptable. The motors are heavy and are large and these aspects 
contribute to undesired design requirements for bulk where the designer 
loses much of the flexibility of innovation which is desired. While the 
motors have been produced in great quantities, their production is 
hindered by the nature of the pole structure carrying their field 
windings. Because of the flared ending or curved tips of the individual 
poles carrying the windings, the procedure for effecting winding is one 
somewhat complex and must be carried out underneath the flared tips on a 
fully assembled rotor. This requirement has impeded design progress which 
otherwise would be realized with motor structures which are simply changed 
to alter performance characteristics. 
To address the performance limitation of electrical noise caused by the 
brush type motors, brushless P.M. d.c. motors have been developed wherein 
field commutation otherwise carried out mechanically has been replaced 
with an electronic circuit. These motors generally provide a higher 
quality performance including a much quieter electrical performance. 
However, this quiet electrical system, wherein the magnetic components 
move as opposed to the field windings, to date, has been implemented in 
relatively larger sizes than otherwise desired. Further, the windings, as 
in earlier motors, are provided beneath flared pole tips on the inside of 
the stator surface and thus are even more difficult to assemble and are 
not amenable to simple alteration for customized manufacture and the like. 
Another characteristic of typical d.c. motors having poles configured as 
steel cores with associated field windings resides in a somewhat inherent 
development of detent torques. At rest, or in a static state, the steel 
poles of a typical rotor will assume an orientation with respect to 
associated permanent magnets which develops flux paths of highest density 
and least reluctance. Thus, were one to hand rotate the rotor of an 
unenergized motor, these positions of rest or detent positions can be felt 
or tactilly detected as well as the magnetic field induced retardation and 
acceleration developed in the vicinity of the detent positions. During an 
ensuing excitation state of the motor windings, this detnet torque will be 
additively and subtractively superimposed upon the operational 
characteristic of the motor output to develop instantaneous speed 
variations (ISV) which are generally uncorrectable, for example, by 
electronics. ISV characteristics also can be generated from mechanical 
unbalance phenomena in the rotor of a motor itself or the bearings thereof 
if they are a part of the rotating mass. Additionally, the effects of the 
above-described detent torque contribution to ISV can be somewhat 
amplified where the characteristics tend to distort the otherwise 
idealized torque characteristic curve which normally will exhibit a form 
of ripple often accommodated for by the addition of more phases to the 
architecture. Where these characteristics of distortion occur, the result 
can be quite pronounced at lower motor speeds. In the past, the output of 
the motors has been smoothed through resort to rotational masses such as 
flywheels and the like, however, for great numbers of modern applications, 
motors exhibiting large ISV characteristics are unacceptable. For this 
reason, spindle motors for floppy disk drives have been configured as 
vector cross products or B cross I devices, sometimes known as voice coil 
motors, which do not employ steel pole structures. Another approach which 
has been employed has been to alter the axially aligned gap of the motors 
to a twisted orientation by developing a step form of association of the 
sheets of steel forming the laminated steel pole cores. Of course, this 
leads to further complexity in the design of the motors and in the 
manufacture of them with internally manufactured field windings. 
SUMMARY 
The present invention is addressed to motion generating apparatus such as a 
d.c. motor of a brushless variety employing a rotor-stator pole 
architecture wherein the working flux gas is disposed axially 
(perpendicularly to the motor axis). This architecture further employs the 
use of field windings which are very simply structured, being supported 
from stator pole core members which, in turn, are mounted upon a 
magnetically permeable base. The core members preferably are formed as 
steel laminates of simple elongate rectangular shape which are nestable 
within the internal channels of simple, insulative bobbins about which the 
field windings are wound. 
A driven component or rotor is configured to mount permanent magnets which 
are movable with the rotor along a locus of motion defined by the stator 
component end regions. By selectively exciting the field windings, torque 
is developed in the rotor in consequence of a unique magnetic path wherein 
flux is directed perpendicularly to the surfaces of the permanent magnets 
carried by the rotor. As a consequence of the simple stator pole structure 
wherein the field windings may be wound about simple bobbins and then 
slideably placed over the core laminates, very significant manufacturing 
savings are avhieved. In addition to this significant simplification for 
manufacture, the structures involved permit the designer a significant 
latitude in design. For example, the windings readily may be altered to 
suit specific needs and the placement and number of stator poles may be 
varied quite readily. Through a unique skewed orientation of the stator 
poles, the deleterious effects of detent torques are significantly 
alleviated to an extent permitting the motors to be employed, for example, 
in conjunction with computer disk drives and the like. Further improvement 
over detent torque characteristic phenomena is achieved by the structuring 
of the permanent magnets employed with the rotor. For example, this 
structuring may be provided such that a form of detent torque cancellation 
is achieved. 
A feature of the invention is to provide motion generating apparatus 
wherein a magnetically permeable base is provided. Upon this base, a 
predetermined number of magnetically permeable core components are mounted 
in an upstanding fashion connected in magnetic flux transfer communication 
with the base and extending along their lengthwise extents to end 
locations arranged to define a locus of selectively spaced pole positions, 
the core components are insertably positioned within insulative devices 
which provide insulation along the lengthwise extent thereof. The field 
windings then are supported upon the insulative arrangement and are 
selectively excitable during an excitation state of the apparatus. A 
driven component such as a rotor is provided which includes a magnetically 
permeable disk shaped support, a select number of thin permanent magnet 
segments formed of magnetic material substantially resistant to 
demagnetization in the presence of flux directed thereinto, fixed to the 
noted support and movable therewith along the locus to provide flat, 
outwardly disposed surfaces extending over the pole positions and 
substantially perpendicular to the lengthwise extents thereof, these 
magnetic surfaces being spaced a predetermined gap width from the end 
locations and being configured having a dimension along the locus selected 
to effect a substantial minimization of static state attraction and 
repulsion characteristics between the driven component and the pole 
positions when the driven component is driven during an excitation state 
by select excitation of the field windings. 
Another feature of the invention is to provide a P.M. D.C. motor which 
includes a magnetically permeable base having a central axis and a 
predetermined number of stator pole components, each having a field 
winding insulated from and surrounding a magnetically permeable core are 
mounted in upstanding fashion from the base to extend along a lengthwise 
extent to an end location. The core components are in magnetic flux 
transfer communication with the base and the pole components are arranged 
about the axis in a manner wherein the end locations thereof define a 
circular locus of stator pole positions. A rotor is provided which is 
rotatable about the aforesaid central axis and which has a magnetically 
permeable mount, a select number of thin permanent magnet segments formed 
of a magnetic material substantially resistant to demagnetization in the 
presence of flux directed thereinto providing discrete outwardly diposed 
surfaces of predetermined field polarity. The permanent magnet segments 
are movable along the circular locus of stator pole positions and the 
surfaces of the magnets are disposed perpendicularly to said core 
lengthwise extents and spaced from the end locations of the stator poles 
to define a gap which is perpendicular to the central axis. 
Other objects of the invention will, in part, be obvious and will, in part, 
appear hereinafter. 
The invention, accordingly, comprises the apparatus possessing the 
construction, combination of elements, and arrangements of parts which are 
exemplified in the following detailed disclosure. 
For a fuller understanding of the nature and objects of the invention, 
reference should be had to the following detailed description taken in 
connection with the accompanying drawings.

DETAILED DESCRIPTION 
As a prelude to considering the instant invention in detail, the instant 
discourse initially looks to the general structuring of a standard P.M. 
D.C. motor. Referring to FIG. 1, a stylized sectional view of such a d.c. 
motor is represented generally at 10. The motor 10 is shown having a 
stator structure 12 having a cylindrical outer casing or shell 14 which 
supports arcuately formed ferrite-type permanent magnets shown 
diametrically oppositely spaced at 16 and 18. Rotationally mounted along 
the central axis of the motor 10 is a rotor 20, the rotor bars or poles of 
which at 22-24 are mounted upon a rotational axle 26. The poles 22-24 
usually are formed as a lamination of steel sheets which facilitates 
magnetic flux transfer in consequence of their multiple surfaces. Each of 
the poles 22-24 is formed having an arcuate or flared outer tip as 
represented, respectively, at 28-30. Tips 28-30 are structured such that 
their outward ends are closely proximate each other to permit flux 
transfer thereacross. As represented at 32 and 34, each rotor pole rotates 
in proximity with the inwardly disposed surfaces of permanent magnets 16 
and 18 to define an air gap which conventionally is referred to as a 
"radial gap". The gap is parallel with axle 26 or the axis of motor 10. 
The final principal feature of the motor 10 is comprised of the field 
windings which are shown at 36-38 wound in conventional form about the 
respective poles 22-24 internally of their outer tip portions 28-30. By 
selectively exciting these field windings, for example, through a 
commutator with brushes, a field is caused to move about the tips 28-30 as 
thr rotor rotates and interact with the magnetic field of permanent 
magnets 16 and 18 to develop motion. As is apparent, a detent torque will 
be developed between the tips 28-30 of the rotor 20 and the permanent 
magnet poles 16 and 18. 
The field windings of motors as at 10 are provided either in a delta or Y 
configuration, the latter sometimes being referred to as a "star" winding. 
Looking to FIG. 2, a representation of a delta winding is provided showing 
pole windings 36-38 in delta form in association with their respective 
pole tips 28-30. For excitation of the delta coupling form from a 
commutator, current is caused to flow, for example, at point 40 by 
application of a plus polarity voltage at such point and ground or 
negative at point 42. Thus, current will flow through winding 37 and a 
current of half the value of that flowing through winding 37 will pass 
through windings 38 and 36 to point 42. The latter half value current 
occurs inasmuch as the two windings 38 and 36 are in series electrical 
connection. 
Looking to FIG. 3, a Y type winding structure for windings 36-38 and 
associated respective pole tips 28-30 is revealed. Assuming current flow 
by application of positive input to point 44 and ground or negative at 
point 46, a current will be caused to flow through winding 36 and thence 
through winding 38. No current flows through coil 37 because of its open 
circuit condition. Thus, in a Y form of structuring, power is on two of 
the windings but not on the third, however, the same amount of current 
occurs in each of the powered windings as at 36 and 38 to derive the same 
drive forces, a performance considered more efficient. 
In structuring of brushless d.c. motors, i.e. motors with no mechanical 
switching for commutation, the general practice is to position the field 
windings in stationary form within the stator of the motor, while mounting 
the permanent magnet components for rotation on the rotor. Referring to 
FIG. 4, a delta form of field winding configuration employed with a 
brushless d.c. motor is revealed generally at 48. The configuration 48 
includes field windings 50-52 which are joined to from a delta formation 
at connector points 54-56. The drive circuit for the configuration 48 is 
shown to be comprised of NPN-PNP transistors Q1-Q2 coupled at point 54, 
NPN-PNP transistors Q3 and Q4 at point 55 and NPN-PNP transistors Q5-Q6 
coupled at point 56. By appropriately positioned and controlled sensing 
devices, for example operating under the Hall effect, these transistor 
pairs can be appropriately switched to excite the field windings 50-52. 
For example, assuming that point 54 has been made positive or excited to 
derive a positive state, point 55 negative, and point 56 positive, then 
current will flow in windings 51 and 52 but not in winding 50. Thus, full 
current resides in two windings, 51 and 52 of full value in a fashion 
similar to a Y structure for a brush commutated motor. 
Now looking to FIG. 5, a brushless d.c. motor formed in accordance with the 
teachings of the instant invention is revealed in perspective at 60. Shown 
in the figure is a cylindrical stator housing 62 above which is positioned 
a flat, relatively thin rotor 64 from which extends a drive shaft 66. 
Looking additionally to FIG. 6, a sectional view additionally reveals that 
the stator housing 62 is formed having a support structure incorporating a 
centrally disposed cylindrical portion having a wall 68 supporting two 
spaced ball bearing type shaft supports as at 70 and 72. Journalled within 
the inner race of these bearings 70 and 72 is the necked down portion of 
shaft 66 shown at 74. A cylindrical spacer 76 is positioned intermediate 
bearings 70 and 72 and the lower disposed portion of bearing 72 is shown 
retained in position by a ring shaped sleeve 78 to complete the lower 
assembly. A spacer form of bushing at 82 upon which the output shaft 66 
rides functions to appropriately space the rotor 64 lower surface 84 from 
the stator structure housing 62. Positioned between the inner cylindrical 
wall 68 and the outer cylindrical wall 86 of the housing 62 are eight 
upstanding stator poles 90-97. These stator pole pieces or components 
90-97 are identically structured and, looking additionally to FIG. 8, each 
stator component is formed of an assemblage of rectangularly shaped stator 
core components 100 formed as a laminate of, for example, three 
magnetically permeable (steel) pole pieces 102-104. In the interest of 
clarity, these individual rectangular pole pieces 102-104 are shown at 
stator pole component 90 in FIG. 7. The stator core components 100 are 
retained together as a laminate by slidable insertion within the 
internally disposed channel of an electrically insulative bobbin 106 
having integrally formed flared ends 108 and 109 (FIG. 8). The bobbins 106 
are formed of a suitable plastic and have an externally disposed winding 
support surface which is wound with a field winding revealed at 112 in 
FIG. 8. Each of the stator pole pieces 90-97 is mounted within a 
magnetically permeable base represented generally at 114. as revealed in 
FIG. 6, the base 114 is configured from four stacked steel disks 116-119 
which form a laminate and within which are formed a sequence of 
rectangular slots within which the extended mounting region of the stator 
core components 100 are inserted and from which such core components as 
well as the entire stator pole structure 90-97 is supported. The 
ring-shaped base disks 116-119 are retained in the position shown by a 
corresponding ring-shaped housing base shown in FIG. 6 at 122. FIG. 7 
reveals further support and alignment of each of the stator pole 
components 90-97 by virture of shallow rounded elongate slots 124 and 126 
formed within the respective inner surface of wall 86 and the outer 
surface of wall 68 of housing 62. Certain of these slots are revealed in 
FIG. 7 and it may be observed that the outer flared portions 108 and 109 
of the bobbins 106 (FIG. 8) slide within these slots 122 and 124 during 
mounting procedures. 
FIG. 6 reveals that the stator core components 100 extend upwardly through 
the top surface of stator housing 62 such that their tips represented in 
the figure at 128 are spaced across an interactive gap from thin permanent 
magnets 130 and 131 of a grouping thereof mounted within a magnetically 
permeable disk shaped mount or part 136 of rotor 64. Looking additionally 
to FIG. 9, these permanent magnet segments are seen to include additional 
magnets 132 and 133 which are spaced by the non-magnetic sections of the 
rotor 64 at 138-141 from magnets 130 and 131. The thin magnets 130-133 
will have a thickness, for example, of 0.060 inch for a typical 
application and are formed of a magnetic material which is substantially 
resistant to demagnetization in the presence of flux directed into them in 
a direct, demagnetizing direction. For example, magnets having such high 
resistance to demagnetization include those formed of samarium, cobalt, 
neodinium, iron, or boron containing magnets, and others in the rare earth 
family. This magnetic material selection is made because of the unusual 
flux interaction developed by the architecture of the instant d.c. motor. 
FIG. 9 further reveals that the arcuate extent of magnets 132 and 133 is 
greater than that of magnets 130 and 131. 
Looking to FIG. 6 it may be observed that the gaps between tips 128 and the 
rotor magnets 130-133 is one which is not "radial" as in typical d.c. 
motors. In the instant motor, the gap is perpendicular to the axis of the 
motor. Thus, instead of flux flowing from rotor tip to rotor tip as 
described above in conjunction with FIGS. 1-3, the flux from the stator 
pole components 90-97 is applied somewhat directly into the faces of 
magnets 130-133. The excitation of the field windings will be seen to be 
designed such that the flux generated from an excited initial stator pole 
component flows through an associated magnet within rotor 64 then through 
the magnetically permeable mount or support 136 and down into a selected 
second stator pole component which may or may not reside in adjacency with 
the initial pole. 
The selection of the number of self-supporting stator pole components 90-97 
as well as their orientation upon the base or base block 114 and the 
number and extent of permanent magnets of the rotor are selected for the 
characteristic torque desired in the operation of the motor of the 
invention. FIG. 7 futher reveals that the stator pole components are 
configured in somewhat nested fashion in that they are skewed from being 
aligned along their lengthwise extents in a radial sense from the center 
of the motor. In the latter regard, it may be observed that the stator 
core components 100 and the overall shape of the stator pole components 
90-97 is one having a directional sense, the rectangular shape shown, 
having an extended lengthwise extent, being preferred. As is apparent, 
there is a broad versatility in designing the motor 10 for a given 
function. Each of the stator pole components, in effect, represents a 
design module which is supported from a stator core component 100 as it is 
inserted within the base block 114 slot. 
Looking additionally to FIG. 10, aspects of this design approach as they 
concern the orientation of the stator pole components as at 90-97 are 
considered. In FIG. 10, a circle 150 is provided to represent the outer 
periphery of a given motor 10, the axis of which is represented at 152 as 
the center of the circle. For demonstrative purposes, a stator pole 
component is shown at 154 having a principal dimension or directional 
sense which is radially aligned through the center of the component as 
represented by the radius 156 drawn through the center 152 of circle 150. 
In similar fashion, a stator component is shown at 158 similarly aligned 
with a radius 160. To provide an arrangement of eight stator pole 
components, radius 160 will be displaced 45.degree. from radius 156. 
Similarly, a third component 162 is shown aligned along radius 164. If the 
components 154, 158, and 162 were to be aligned as shown wherein their 
principal dimension or directional sense is radially aligned, then the 
stator structure would exhibit spaced apart concentrated areas of steel 
which would develop a more pronounced undesirable detent torque 
characteristic. To minimize this effect, the pole components are turned 
about their axes such that component 154 assumes, for example, an 
orientation as shown in phantom at 166. Similarly, component 158 can be 
rotated about its center such that it assumes the orientation shown in 
phantom at 168. It may be observed that the amount of steel or the 
lengthwise extent of the stator pole arrangement as observed from the 
center 152 encompasses a greater angular extent represented at .theta.1 
and .theta.2. By not so orienting the pole components, the lesser angle 
.theta.3 is developed as shown in conjunction with pole component 162. 
Thus by so skewing the pole components as shown, the period of the detent 
torque otherwise developed will not have changed, but the amplitude of the 
detent torque is reduced considerably. Further, the center of magnetic 
influence has a tendency to move outwardly from the mechanical center of 
the motor structure. Generally, in the design of the motor 10, it is 
desired to maintain the inductance of the motor low such that low 
electrical time constant is achieved. This permits faster switching of the 
field windings of the stator. However, some drive developing flux density 
is surrendered. Recall with the instant approach, that there is a direct 
flux transfer in opposition to the permanent magnet field which would 
otherwise tend to demagnetize them. In effect, there is a different field 
interaction to achieve motor motion which might be considered a "B cross 
B" approach. The field flow, for example, is one extending outwardly from 
pole component 154 and through an adjacent permanent magnet, having a mu 
of 1, thence through the permeable rotor support 136 to an oppositely 
excited stator pole component, for example at 162. Accordingly the fields 
developed create a repelling force at one rotor position while becoming 
attracting at another position, thus achieving rotor movement. 
Where high volume production is contemplated for a given design of the 
motor of the instant invention, then efficiencies may be achieved by 
providing castings of the permeable magnetic base of the motor with 
integrally formed stator core components as described at 100 in FIG. 8. 
Powder metallurgy techniques may be used for such castings. With the 
arrangement, the bobbin structure 106 having been previously wound with a 
field winding 112 is simply inserted over the upstanding integrally case 
core component 100. 
Looking to FIG. 11, the motor 10, as representing an eight pole embodiment, 
may be considered and analyzed from a developed or linear aspect. In this 
regard, consider an axis of movement as represented by line 170. Line 170 
may be arbitrarily divided into 30.degree. segments of a total 
circumferential extent of 360.degree.. Beneath these subdivisions of 
degrees at line 170, the positions of each stator pole may be located as 
represented by an array 172 of arrows, each arrow being assigned a 
designated numbered pole from 1 through 8. Note that poles 7 and 8 are 
repeated on the left of the drawing to clarify the analysis at hand and, 
further, the assignment of 30.degree. divisions is expanded to the left at 
line 170 in correpsondence therewith. Now, the location of the peranent 
magnets may be assigned. For purposes of illustration, four permanent 
magnet poles having full 90.degree. orientations on the rotor of the motor 
may be provided as represented by blocks 174-177. By so assigning the 
extent of the permanent magnets of the rotor, each one of the permanent 
magnet poles will be symmetrically disposed over either one or a pair of 
the stator pole components of array 172. These two positions will 
represent the relative orientations achieving least reluctance between the 
rotor and stator and highest flux density, i.e. they represent static 
detent positions or positions of zero static torque. In this regard, the 
orientation represented by blocks 174-177 is one wherein one stator pole 
or component is centered with respect to the extent of any given rotor 
magnet. The other available static detent orientation is represented by 
the magnets now numbered 180-183. In the latter arrangement, two stator 
pole components are symmetrically disposed with respect to each permanent 
magnet. 
Looking additionally to FIG. 12, a torque graph aligned with the pole array 
172 of FIG. 11 is provided wherein, on somewhat exaggerated scale, torque, 
+T, meaning a torque in the direction to the right in the sense of FIG. 11 
is plotted in conjunction with a corresponding negative valuation of 
torque, -T, or a torque urging the rotor to move to the left. Employing 
FIG. 12, a detent torque curve may be developed. In this regard, the 
influence of magnet 174 may be considered as the rotor is moved to the 
right in the sense of the drawing. As that movement commences to occur, 
the torque experienced will be one of retardation, the rotor being drawn 
to the left or in the negative torque sense so as to retain the detent 
rest status. Accordingly, for an interval representing 221/2.degree. as 
shown at curve 186, the static curve will be negative representing 
retardation. However, at that position where curve 186 crosses the 
rotational position axis 184, an accelerating influence will be observed 
which is represented as a positive torque or torque to the right in the 
sense of the figure. Accordingly, torque will be developed as represented 
at curve portion 188 for an ensuing 221/2.degree.. Without correction, 
such a detent torque characteristic will severely distort the energized 
output torque characteristic curve of the motor under consideration. To 
significantly alleviate the impact of such detent torque characteristics, 
the rotor magnet 174-177 structure may be organized such that one-half of 
the magnets thereon are arranged so that their detent orientation is 
directly in line with a given pole, while the other one-half of the 
magnets on the rotor are oriented so that their stator orientation, for 
detent torque purposes, is one aligned between the stator poles as in 
magnets 180-183. Returning to FIG. 11, the result may be plotted with 
respect to development line 170 such that a permanent magnet array 190 is 
developed incorporating permanent magnets 192-195. Array 190 thus 
represents a shortening of components within magnet grouping 180-183. The 
shortened magnets 192 and 194 now generate curve components 196 and 198 in 
FIG. 12 which are seen to effect a substantial cancellation of detent 
torque curves 186 and 188. This arrangement has been observed to reduce 
the effect of the static detent torque by a factor of 5 or 6 with respect 
to rotor magnet segments of equal proportions. It may be observed that the 
rotor arrangement 130-133 of FIG. 9 corresponds with the array development 
190 of FIG. 11. 
Now, considering an energization situation with respect to the developed 
magnet architecture of FIG. 11, assume that stator component or pole 1 is 
energized in a north (N) magnetic sense, then stator pole 3 would be 
energized in a south (S) sense while pole 5 would be energized in a north 
(N) sense and pole 7 in a south (S) sense. By so energizing the system a 
force is created on any permanent magnet in line with pole 1 which will 
require a satisfaction of lining up, for example with pole 3. This can 
only occur after a rotor movement amounting to the equivalent of 
90.degree.. Looking again to FIG. 12, this drive effect will create a 
torque in a positive sense represented by curve 200 which has a peak value 
at the 45.degree. location. Notice that the period for the energizing 
torque is 180.degree., whereas the corresponding period for the static or 
detent torque is 45.degree.. If the latter static detent torque 
represented by curve segments 186 and 188 were permitted to remain, then a 
dramatic distortion of the curve 200 will be seen, as represented by the 
dashed summation curve 202. However, assuming an ideal case, the energized 
output of the motor under consideration, when the stator windings are 
appropriately energized, will develop a sequence of positive torque output 
curves including earlier-described curve 200 and subsequent output curves 
204 and 206, etc. With the arrangement shown, curve 200, is developed by 
the energization of stator pole components 1, 3, 5, 7. Correspondingly, to 
maintain a positive torque sense, curve 204 is developed with the 
energization of stator poles 2, 4, 6, 8. The switching system then repeats 
the energization of stator pole components 1, 3, 5, 7 in an opposite polar 
sense to generate curve 206. Generally, the motor is commutated with Hall 
effect sensing devices which are positioned to carry out commutation at 
the intersection of curves 200 and 204, i.e. at point 208 or point 210. 
Thus, for the switching at hand, sensing would occur at sensor positions 
H1 and H2, as shown by the labelled arrows in FIG. 11 and also shown 
positioned in FIG. 7. This is suited for a two-phase operation with 
unipolar drive. These sensors H1 and H2 may be combined with a relatively 
simple solid-state binary gate array to carry out appropriate switching in 
conjunction with Boolean logic as follows: 
______________________________________ 
H1 H2 
______________________________________ 
1 0 
0 0 
0 1 
1 1 
1 0 
______________________________________ 
It is interesting to observe that by altering the control switching of the 
instant motor a variety of drive functions can be developed. For example, 
curve 200 can be generated to the extent where it again reaches an 
intersection with position axis 184. Under these circumstances, 
performance will be that of a step motor. 
Looking to FIG. 13, a control circuit which may be employed with the motor 
of FIGS. 6 and 9 is schematically portrayed. The circuit is basically a 
series of logic gates which perform in conjunction with the 
earlier-described Hall effect devices H1 and H2 which function to sense 
rotor position. The gate array then functions to actuate a motor drive 
circuit of conventional variety. In the Figure, Hall effect sensing 
devices H1 and H2 which have been described in terms of position in FIG. 
11 and shown in FIG. 7 are respectively represented by blocks 220 and 221. 
Provided, for example as Sprague type UGN3030 digital type Hall effect 
sensors, the output of Device 220 is provided at line 222, while the 
output of device 221 is represented at line 224. Line 222 is coupled 
through line 226 and pull-up resistor R1 to plus power supply, while 
correspondingly, line 224 is coupled via line 228 and pull-up resistor R2 
to that same plus supply. Accordingly, the output of the sensors 220 and 
221 at respective lines 222 and 224 is either a logic 1 state as the plus 
voltage supply, while a corresponding zero state will be presented as 
about a zero voltage value. Thus influenced by the opposite polarities of 
the magnetic field of the magnets of the rotor, for the instant 
demonstration, when a north pole is influencing the Hall effect device a 
"1" logic output is developed, while a south polar influence will be 
represented as a "zero" logic state. It may be noted that this logic can 
be reversed by simply turning the devices upside down in their mounting. 
The Hall effect devices 220 and 221 are mounted apart by an amount of 
45.degree. of rotation of the rotor of the motor design incorporating 
eight poles and four rotor magnets. Thus, a two phase form of the motor 
architecture is developed and as the rotor is rotated, the pattern of 
logic represented by the above-noted tabulation occurs. 
The figure shows that the outputs at lines 222 and 224 are directed to an 
array 230 of exclusive OR gates shown at 232-235. Gates 232-235, in 
conventional fashion, provide a zero output when the inputs thereto are 
logic 0, 0 as well as when the inputs are a logic 1, 1. Output line 222 is 
shown directed to one input of gate 232, while corresponding Hall effect 
device output line 224 is shown directed to one input of gate 233. The 
opposite input to these gates 232 and 233 emanates from a directional 
control switch S1 through lines 236 and 238. Thus, when switch S1 is 
coupled to plus supply through line 240 the motor will be driven in a 
counter-clockwise direction, while when the switch is thrown to its 
terminal at line 242 the motor will be driven in a clockwise direction. 
The outputs of gates 232 and 233 are provided respectively at lines 244 and 
245 which are directed through respective inverters 246 and 247. The 
outputs of inverters 246 and 247 are provided respectively at lines 248 
and 240 which are coupled with the respective P.sub.A and P.sub.B input 
terminals of a dual, H-bridge motor driver 250. Driver 250 may be 
provided, for example, as a type UDN-2993B Dual H-bridge Motor Driver by 
Sprague Electric Company of Worcester, Massachusetts. Each of the included 
full-bridge drivers has separate input level shifting, internal logic, 
source and synch drivers in an H-bridge configuration, and internal clamp 
diodes. Additionally, a phase input to each bridge determines load-current 
direction. 
The output of device 250 is shown providing for simultaneous energization 
of field windings 1, 3, 5, and 7 as described in conjunction with FIG. 11 
via lines 252 and 254. Similarly, the ouput provides for the simultaneous 
excitation of correpsonding field windings 2, 4, 6, and 8 through lines 
256 and 258. 
Returning to gate array 230, it may be observed that the outputs of Hall 
effect devices 220 and 221 additionally are directed via respective lines 
260 and 262 to the inputs of gate 235. Gate 235 then functions to develop 
a tachometer form of signal at its output at line 264. This signal may be 
employed, for example, to determine motor speed or for use in conjunction 
with speed regulation circuits. 
Line 262 is coupled through line 266 to the one input of gate 234 of array 
230, while the other input to the gate is derived from line 260 via line 
268. Thus, the two outputs of Hall effect devices 220 and 221 are summed 
at the input of gate 234 and this information is used with other gate 
logic to supply the motor driver circuit 250 with requisite signals for 
developing unipolar drive or bipolar drive operation. In this regard, 
under unipolar drive, one-half of the field windings, i.e. as at 1, 3, 5, 
and 7 are driven and, subsequently, field windings 2, 4, 6, and 8 then are 
driven. The sequence then reverts back to effecting excitation of poles 1, 
3, 5, and 7 in an opposite polar sense and subsequently the same form of 
drive is applied to windings 2, 4, 6 and 8, whereupon the sequence repeats 
itself. Under bipolar drive, all field windings 1-8 are driven 
simultaneously in a predetermined sequence of polar designations. The 
development of these bipolar or unipolar drive attributes is achieved by 
appropriate signal inputs to the enable terminals, E.sub.A and E.sub.B of 
the motor driver circuit 250. The logic to these inputs is developed from 
gate 234 of array 230. Looking to that gate it may be observed that the 
output thereof at line 270 is directed to a line 272 which inverts the 
output signal at inverter 274 for presentation via line 276 to one input 
of NAND gate 278. The opposite, non-inverted output of gate 234 is 
directed to one input of corresponding NAND gate 280. The opposite inputs 
to gates 278 and 280 is derived via respective lines 282 and 284 which 
carry either +v or ground in consequence of the orientation of a switch 
S2. The latter switch, when connected to +v supply via line 286 provides 
for unipolar drive logic, while when coupled via line 288 to ground, 
provides for bipolar drive logic. The logic outputs of gates 278 and 280 
are shown at respective lines 290 and 292 being directed to one input of 
respective NAND gates 294 and 296. The output of gate 294 at line 298 is 
directed through inverter 300 and line 302 to the E.sub.B enable gate for 
phase B of driver 250, while the corresponding output of NAND gate 296 at 
line 304 is directed through inverter 306 and line 308 to the enable 
terminal, E.sub.A for phase A of the motor driver 250. 
To turn the motor on and off, the opposite inputs to NAND gates 294 and 296 
is coupled via lines 310 and 312 to the output terminal of switch S3. With 
the arrangement shown, the motor is turned on when switch S3 is coupled 
with +v through line 314 and is turned off when the switch S3 couples line 
310 to ground via line 316. Generally, to shut the motor off, the two 
enable inputs, E.sub.A and E.sub.B are held at zero logic level while 
turning the motor on, provides for their selectively receiving a logic 
high signal. 
The gate array 230 including the NAND and inverter logic shown in the 
figure are arranged such that a brushless type motor drive function may be 
carried out for use in computer devices and the like. By altering this 
gate input logic, the motor of the invention can be caused to assume any 
of a variety of operational modes of performance depending upon the needs 
of a particular user. Thus, the univeral form of motor structure is 
achieved which may be varied by appropriate selection of input logic. For 
example, if it were desired to operate the motor of the invention as a 
step motor, then the Hall devices would not be employed but an inputting 
clock signal would be used in their place in conjunction with a 
reconfigured array of logic gating. Further, both a Hall device input and 
a clock input may be used together wherein the Hall effect devices are 
employed to develop position data in conjunction with the clock input to 
evolve a closed loop form of performance. Another application of the gate 
array may, for example, provide for operation over a limited angle of 
rotation as a torque device. For all of these applications, the logic is 
developed on a gate array chip customized to the user's desires, for 
example, by a mask change at the semiconductor level. 
The motor architecture of the invention can be altered to different 
combinations of numbers of stator pole components and rotor permanent 
magnet components as part of its unique modularity. In this regard, 
reference is made to FIG. 14 where a stator structure 318 is shown having 
a permeable base 320 structured similarly to base 114 which supports and 
is in magnetic communication with 14 stator pole components 321-334. Each 
of these components may be structured identically to that discussed in 
FIG. 8. A rotor mounting shaft is shown at 336 extending through an 
appropriate support structure including bushings, bearings and the like, 
as discussed in conjunction with FIG. 6. This shaft 336 extends to a rotor 
structure similar to that discussed in connection with FIG. 6 and 
represented at 340 in FIG. 15. Note that the rotor 340 includes six 
permanent magnet sectors 341-346 which are of the same arcuate extent with 
respect to their relative instantaneous positioning before the stator 
components 320-334. As before, these magnets are thin and are selected 
having a significant resistance to demagnetization occasioned by a direct 
interaction of an opposing field, as is developed with the stator 
components 321-334. 
Looking to FIG. 16, a development of a 14 stator pole, six permanent magnet 
rotor pole motor assemblage, as discussed in connection with FIGS. 14 and 
15 is set forth in similar fashion as FIG. 11. Accordingly, the rotational 
locus of the permanent magnets is identified in terms of degrees from 
0.degree. through 360.degree. and the permanent magnets 341-346 are shown 
having a rotational influence representing 60.degree. of rotation per 
magnet. Essentially no variation in this locus of association between the 
stator components and the magnets is provided. In the interest of clarity, 
the stator pole component array described at 321-334 in FIG. 14 is 
represented by arrows which are numbered 1 through 14 in conjunction with 
the above-noted general designation. Stator position 1 in the development 
is arbitrarily positioned at the center of magnet 341 or at a 30.degree. 
position. By so positioning the magnet at this location and assuming equal 
orientations of the stator components 321-334, then the stator centers of 
influence will be mutually separated by an amount of 25.7.degree.. This 
results in stator component number 8 being at the center of permanent 
rotor magnet 344 as shown in the drawings. To study an energization drive 
scheme for the stator components, certain arbitrary initial assumptions 
are made. In this regard, it is assumed that a maximum torque contribution 
between the rotor and a given stator pole occurs when that stator pole in 
its energized state is located closely adjacent the north-south (N-S) 
union between two adjacent rotor magnets. In the assumption to follow, 
where this positioning occurs, then the stator position is assumed to be 
contributing 100% of available torque. A positive direction is assumed, 
for the instant demonstration, to be in a direction from left-to-right in 
the sense of FIG. 16. Thus, where the rotor has moved such that the stator 
pole is displace 10.degree. away from the center of an associated rotor 
magnet, then it is assumed to be contributing 40% of otherwise maximum 
available torque either in a positive or negative direction depending upon 
excitation. Where the stator pole is positioned 20.degree. away from the 
center of an associated rotor magnet, then it is closer to the union of 
that magnet with the next succeeding permanent magnet and its developed 
torque is arbitrarily assigned a 70% available contribution. Finally, 
where the rotor magnet has been so positioned that the stator pole is 
30.degree. away from the center of the magnet, then it is essentially 
adjacent to the union of that magnet with the next rotor magnet and it is 
assigned a 100% contribution to available torque. The relative 
contributions for a given movement of the rotor 340 then can be charted. 
Accordingly, these contributions are established for rotation of the rotor 
340 in 10.degree. increments under the offset amount column labelled 
"O.S." in the figure. Because of the flexibility inherent in electronic 
control over the excitation of the stator field windings at components 
321-334, selections of which windings are to be energized and the polar 
sense of such energization can be assigned on a basis tending to maximize 
torque or any other parameter desired by the designer. For the instant 
illustration, north-south polar assignments (N,S) are provided for each of 
the windings of the stator components represented in the figure as 1-14. 
Beneath each of the stator winding positions, there is assessed a 
contribution of torque on the above percentage basis along with the 
direction which that torque may take. For example, at 0.degree., there is 
no torque developed at stator component locations 1 or 8. However, as the 
rotor is moved from left to right 10.degree. (in the sense of FIG. 16), 
then the contribution at the first stator component position 1 becomes 40% 
as it does at pole 8. Note that the values for the positions pole 8 
through pole 14 repeat those given for positions 1 through 7. However, the 
assignment of polar sense to the excitation of the stator windings for 
component locations 8 through 14 are reversed with respect to the position 
1 through 7. When operating this motor as a torque motor with limited 
rotation, all the poles that are a positive contributing factor or force 
may be summed. These contributing percentages then can be summed as set 
forth in the vertical column labelled "Cont.Sum". However, in arriving at 
these sums, it may be observed that stator pole component positions 4 and 
11 are not included, inasmuch as their contributions are essentially 
negated by the combination positive and negative values. The shape of the 
combined torque curve can be modified depending on which stator poles are 
summed. In the application shown, twelve stator poles are summed to give a 
broad (flatter) top torque curve for torque motor operation. When 
operating this design as a continuously rotating motor, an appropriate 
number of stator poles may be summed to represent a "phase" of motor 
excitation. For instance, for three phase (3.phi.) operation four stator 
pulses are summed for each phase and commutation occurs at approximately 
20 degree increments. 
When the assignment of excitation locations is appropriately set forth, 
then each stator pole contribution may be plotted as represented in FIG. 
17 which has been developed in identical manner as the plot represented at 
FIG. 12 with respect to curves 200, 204, and 206. Thus, optimization of 
motor design may be achieved. The above analysis indicates that, while a 
first evaluation would show that a motor having a combination of 12 stator 
components in conjunction with six permanent magnet rotor components would 
provide maximum energized torque output, investigations as above, have 
found that the minimization of detent torque phenomena is improved with 
the addition of a thirteenth stator component and is further improved over 
that configuration with the provision of fourteen stator component 
location as described above. 
From the foregoing it may be observed that the motor of the instant 
invention represents a unique form of drive architecture which is more 
fascile to produce and thus, is less expensive. The design of the motor is 
such that it is readily developed in a modular sense such that it may be 
modified or customized to suit the needs of a particular application. In 
this regard, the windings are readily altered and the flexibility of 
design is such that motors produced with the system can range from 
consistent torque output devices to step-type motors or torque devices of 
limited rotation. As is apparent from the development diagrams, the 
architecture can be applied to a linear form of drive device. 
Since certain changes may be made in the above-described apparatus without 
departing from the scope of the invention herein involved, it is intended 
that all matter contained in the description thereof or shown in the 
accompanying drawings shall be interpreted as illustrative and not in a 
limiting sense.