Note: Descriptions are shown in the official language in which they were submitted.
-- 1 --
TANDEM COMMUTA~ORLESS DC MACHINE
Technical Field
The present invention relates generally -to commutator less DC
machines of the axial air gap type which readily function as
either DC motors or DC generators. Specifically, the present
invention relates to a DC machine having a plurality of disk-like
stators elements and one or more interleaved disk-like rotor
elements adapted to produce axial magnetic flux in the air gaps
between their adjacent planar surfaces, and employing umquely
configured, radially oriented armature conductor winding elen~nts
rotatable in the air gaps to produce the desired electromechanical
transducer actions. Both a basic embodiment, and an improved
embodiment comprising a number of basic units in tandem are disk
closed.
Background Art
Both ccmmutatorless rotary machines and axial air gap rotary
machines are well known in the electrical engineering art, and
have been the subject of much study and development over the years.
In their most basic forms, these two features are often found in
machine embodiments wherein thy magnetic flux passes in the same
direction from one member to the other over the whole of a single
axial air gap area, and are designated as cyclic, or alternatively
as homopolar machines While the present invention goes very far
beyond the basic cyclic approach and represents an entirely new
family of DC machines, it is of some interest to briefly describe
prior art machines exhibiting the commutator less and axial field
features.
--3--
US. Patent 1,465,251 to Broluska et at discloses an early
(1920) commutator less DC machine having a plurality or inter-
leaved stators and rotor disks wherein radially oriented armature
conductors are immersed in axially directed magnetic fluxes to
produce either motor or generator action The design however,
employs a totally unidirectional magnetic flux which is
customary and conventional. This purely unidirectional field
approach, unfortunately calls for the segmentation of the
armature conductors, which in turn gives rise to the need for
a set of collector rings and rollers which engage the outer
circumferences of the roller disks. The technical necessity
for the collector ring structure is well documented, and a
rigorous presentation of the phenomenon involved may be found
in the description of the "Multi-Spoke Wheel" generator on pages
57-69 of the text "Flux Linkages and Electromagnetic Induction"
by LO Boyle. (Dover Publications, New York, 1964).
More recent prier art homopolar machines are exemplified
by US. patents 3,743,874 to Shabbier and 3,699,370 to Colloidal.
Additional prior art approaches in the area of commutator less
and/or axial field machines are disclosed in US. patents
3,169,204 to Myers et at; 4,082,971 to Mohawk et at; 4,187,441
to Only; and in an IBM TUB authored by C. Dung, dated March 10,
1981.
Summary Of The Invention
__
It is therefore a primary object of the present invention
to provide an improved commutator less DC machine which may
readily function as either a DC motor or a DC generator.
Another object of the present invention is to provide a
DC machine which will be largely devoid of the design
limitations and operational problems associated with the use of
conunutation devices of all types.
, ,=~" I,
,, .
A further object of the present invention is to provide a
basic commutator less DC motor having axially oriented magnetic
flux between Lnterlea~ed stout and rotor disks, wherein the
rotor disks carry radially oriented armature conductors which
are uniquely interconnected and terminated at a pair of slip
rings; and wherein the magnetic flux incident upon the two
planar surfaces of any one rotor so are oppositely directed
thereby producing net torques which are directly additive
resulting in heretofore unrealized superior DC motor performance.
A yet further object of the present invention is to provide
a basic commutator less DC generator having axially oriented
magnetic flux between interleaved stators and rotor disks, wherein
the rotor disks carry radially oriented armature conductors which
are uniquely interconnected and terminated at a pair of slip
rings; and wherein the magnetic flux incident upon the two planar
surfaces of any one rotor disk are oppositely directed thereby
producing ems which are directly additive resulting in hereto-
fore unrealized superior DC generator performance.
A still further object of the present invention is to pro-
vise an improved co~mutatorless DC machine wherein the advantages
of the basic DC motor and basic DC generator outlined above are
achieved by combining a number of the basic unit together in
tandem.
By means of a number of illustrative and preferred basic
and improved embodiments, the present disclosure teaches the broad
principles of a DC machine having axially oriented magnetic flux
between interleaved Syria and rotor disks herein the rotor disks
carry radially oriented armature conductors which are uniquely
it reconnected and terminated at a pair of slip rings. The mug-
netic flux incident upon the two planar surfaces of any one rotor disk are oppositely directed thereby producing ems or
torques, which are additive resulting in heretofore unrealized
electromagnetic transducer actions.
Brief Description s
Additional objects and advantages of toe invention will
become apparent to those skilled in the art as the description
proceeds with reference to the accompanying drawings wherein:
FIG. 1 is half of a vertical cxoss-section through a
basic embodiment of a commutator less DC machine according
to top present invention;
FIG. 2 is a detailed vertical cross-section of the rotor
assembly shown in FIG. l;
FIG. PA and 3B snow side and end views, respectively, of
a typical rotor flange;
FIG. 4 is a detailed vertical cross-section of the stators
assembly shown in FIG. l;
FIGS. PA and 5B show side and end views, respectively, of
an illustrative plain type stators flange;
FIGS. PA and ÇB show side and end views, respectively, of
a typical core type stators flange
FIG. 7 is a highly schematic perspective drawing ox a
complete armature winding arrangement or a four-windinq-element,
three-section DC machine according to the present invention;
FIG. R it a simplifies electrical equivalent circuit cores-
pounding to the complete armature winding arrangement of FIG. 7
when used as a DC generator;
FIG. 9 is a simplified electrical equivalent circuit of
a complete armature winding arrangement for an eight-winding-
element, seven-section DC machine when used as a DC Myra
FIG. 10 is a simplified electrical equivalent circuit of
: a typical four winding stators field arrangement;
FOG. 11 shows typical magnetic circuits and flux paths of
the basic embodiment of FIG. 1, in highly schematic form;
FIGS. 12 and 13 show enlarged portions from FIG. 11) of
typical magnetic circuits and flux paths in Fleming's Rules
interaction regions for, respectively, operation as DC motors,
and as DC generators;
4'7
FIG. 14 is a vertical-cross section through an improved em-
bodiment of a commutator less DC machine according is the present
invention;
FIG. 15 shows typical magnetic circuits and toe resulting
flux paths of the improved embodiment of FIG. 14, in highly
schematic form;
FIG. 16 is a perspective drawing of a composite armature
winding arrangement for a four-winding-element,eleven-section,
three machine unit configuration corresponding to the improved
embodiment of FIG. 14;
PIG. 17 is a simplified electrical motor equivalent circuit
corresponding to PIG. 16, showing the array of torque producing
means;
FIGS. AYE and 18B show a simplified electrical equivalent
circuit of a typical four-winding, three machine unit stators field
arrangement;
FIG. 19 shows operating polarities/senses of a tandem DC
machine while functioning as a commutator less DC motor;
FIG. 20 is a simplified electrical generator equivalent
circuit corresponding to FIG. 16, showing the array of voltage
producing means; and
FIG. 21 shows operating polarities/senses of a tandem DC
machine while functioning as a co~mutatorless DC generator.
Detailed Description of the Preferred Embodiments
A Basic Embodiment
referring first to FIG. 1, there is shown a basic embodiment
of a commutator less DC machine according to the present m mention.
FIG. 1 shows half of a vertical cross-section through a multiple
disk, simply configured DC machine 10. As a brief introduction,
an overall DC machine 10 is shown as comprising two major sub-
assemblies including a multiple flange rotor assembly 12, rotatable
mounted within a multiple mating flange stators assembly 14. The
rotor assembly 12 includes a plurality of spaced apart rotor flanges
16 assembled onto a central shaft 18 which is concentric with a
machine axis of rotation 20. The stators assembly 14 includes a
corresponding plurality tress one) of spaced apart stators flanges
22, mounted within a hollow cylindrical yoke 24, which yoke forms
part of the outer casing of the DC machine 10. A pair of circular
end yokes 26F and 26R are affixed to the front and rear ends
respectively of the cylindrical yoke 24 to form an enclosed
compar~ent. The ends of the central shaft 18 pass through the
end yokes 25F and 25R via circular openings 28F and 28R, respect-
lively, and the shaft ends ye suitably retained and fitted with bearings snot shown) by well-known and conventional means. A pair
of slip rings 30F and OR are concentrically affixed on alternate
ends of the central shaft 18 and serve as the electrical input/output
terminals for a plurality of armature wind in elements distributed
over the rotor flanges. A typical armature winding element 32 is
shown in cross-section as being terminated at its forward end to the
slip ring 30F via a contact 34, and at its rearward end to the slip
ring 30R via a contact 36. The armature winding element 32 is con-
figured as a discreet electrical wire-like conductor, shaped to
follow the outer contours of the plurality of rotor flanges, and
appears in cross-section as a continuous and fairly regular
serpentine path confined to a particular radial plane, as is
detailed below.
I '7
The structure and functions of each of the above elements, as
well as additional elements, are described in more detail herein
below. It is worthy of note that thy! elements outlined above are
applicable to operation of the DC machine 10 as either a commute-
topless DC motor or as a commutator less direct DC generator. The term "direct DC" denotes that as a DC generator, the output voltage
is produced as a continuous unidirectional output and does not
require commutator action for rectification into DC.
Referring now to FIG. 2, there is shown a detailed vertical
cross-section of the rotor assembly 12 of FIG. 1. In the basic
embodiment of FIG. 1, a seven-section DC machine is shown, the
seYen-sectio~ rotor assembly depicted corresponds to that embody
mint. The rotor assembly 12 is pictured as comprising a plurality
of rotor flanges 16 longitudinally stacked along the central shaft
18. Reference to FIGS. PA and 3B show each of the flanges 16 to
be generally disk shaped, and to haze a thickness in the axial
(or longitudinal direction at its outer periphery of "if". The
flanges 16 further have a rim boss 38 at their inner periphery, and
a centrally located opening 40 to admit toe central shaft 18. The
rim boss 38 has an axial extent slightly larger than tub tycoons
"t " of the flange, and a radial dimension "rub" very much less than
the radial dimension "or" of the flange The flanges 16 are made
of material having predetermined desired magnetic properties and
may illustratively be of forged or cast steel. When assembled as
a seven-section embodiment as shown, the seven individual flange
16 (plus front and rear magnetic end pieces 38l and 38") create
an armature core region 42 by virtue of the increased mass of mug-
netic material provided by the thickened rim kisses and end pieces
being longitudinally stacked. Thy armature core region 42 (India-
acted generally by the multi headed arrow symbol of FIG. I so formed functions similarly to the armature core of a conventional
DC machine. The central shaft 18 may be made of steel suitable for
supporting the various rotor components during their high speed
rotation operation, and the entire assembly may be fastened together
by conventional means.
47
A wide variety of complete armature winding arrangements may be
used in conjunction with the rotor assembly of FIG. 2 depending on
the basic use to which the machine is being put (i.e., motor or
generator); and further depending on the particular electrical and
mechanical characteristics (i.e., electrical power/torque/speed) which
it is desired that the machine is to exhibit. In the embodiment of
FIG. 2, two armature winding elements are shown. These are winding
elements 32 and 32', both of which are identical and contain a to-
tat of seven contoured portions, corresponding to the number of
rotor flanges of the embodiment. Only the winding element 32 will
be described, it being understood that the winding element 32'
(plus other winding elements equally spaced circumferential around
the rotor flanges - not shown) will be identical. Basically, the
winding element 32 is a count m use electrical conductor, such as
a length of copper wire, formed into a serpentine contour to fit
along the surfaces of each of the stack Go rotor flanges in a rotor
assembly. For purposes of clarity, the winding elements 32 and 32'
are shown as affixed on the outer surfaces of the flanges. Winding
elements 32 and 32' ye confined to a single plane containing thy
axis of rotation 20, around which axis the plane (and the two winding
elements rotate. The plane containing the wincing element 32 is
bounded at its radially inwards extremity (lower edge as shown) by
- a tine parallel to the axis 20, and the plane containing the winding
element 32' is bounded at its radially inwards extremity (upper edge
as shown) by a line parallel to the axis 20. In an alternate embo-
Dante, the winding elements may be affixed into shallow slots (not
shown) formed into the flat side surfaces of the rotor flanges. Each
extremity of the winding element 32 is connected to its adjacent slip
ring for electrical contact. The slip ring 30F is mounted around the
3Q magnetic end piece 38' and insulated from it (concentrically with
the rotational axis 20), and connects with the winding 32 at the
contact point 34. Slip ring CRY is similarly insultingly mounted
around the magnetic end piece 38" and connects with the winding 32 at
the contact point 36.
'7
--10--
A clearer description of complete armature winding arrangements
contemplated may be had with reference to the perspective drawing of
FIG. 7, along with its corresponding simplified electrical equivalent
circuit of FIG. 8, m addition to the aforementioned FIGS. 2, PA
and 33. FIG. 7 shows a complete armature winding arrangement for
a DC machine coI~prisi~g, illustratively, a three-section rotor
assembly (i.e., three rotor flanges); and also comprising, illustra-
lively, four armature winding elements of the type 32 circumferen-
tidally spaced at 90 intervals around the rotor flanges. The winding
element designated as 32(0) corresponds nominally to the winding
element designated 32 in FIG. 2; while the winding element design-
ted 32tl80) corresponds nominally to the winding elements design
noted 32' in PIG. 2. The winding elements 32~0 s d 32(270)
which are not shown in FIG. 2, along with the 32(0) and 32(180)
winding elements are all connected in electrical parallel via Lye
termination of their corresponding extremities on slip rings 30F
and 30R. The number of rotor sections it shown in FIG. 7 as being
three, as compared to the even section embodiment of FIG. 2, largely
to provide an uncluttered illustration. In actual co~mutatorless
DC machines designed according to the principles taught herein,
it is contemplated that the number of rotor sections could be as
few as one, or as many as several dozen or more.
In the electrical equivalent circuit of FIG. 8, which is shown
for the case where the DC machine is being operated as a DC generator,
it is seen that the winding element designated 32C0) comprises
six independent em generators depicted as a pair of adjacent circle/
dot symbols I each circle of which corresponds to a radial
portion of an armature minding element. Thus, the winding portion
a-b-c-d corresponding to the first one of the three sections of
winding ODE) of FIG. 7 is electrically equivalent to the two em
generators designated a-h and c-d of the first one of the three
sections of winding 32(0l of FIG. 8. In like manner, the two
other sections of winding 32(0l, namely e-f-g-h and i-j-k-l of
FIG. 7 translate into the four em generators e-f and g-h, plus
i-j and k 1 of FIG. B. The remaining windings 32C90), 32(180),
~~ 7
and 32 (270), of both FIG. 7 and Fit;. 8 are similarly related. In
short, a complete armature winding arrangement consists of a number
of armature winding elements, each spanning from one slip ring to
the other; all of the armature winding elements being in parallel
between the slip rings. Conventional sets of brushes (not shown
contact the slip rings, and leads Fran the bushes are brought out
to the machine terTninal board for suitable external interconnections.
A further alternate embodiment of the present invention is shown
by way of the simplified electrical equivalent circuit of FIG. 9.
This embodiment depicts the DC machine 10 while it is bring operated
as a commutator less DC motor. By reference to a plurality of torque
generating elements depicted as a pair of adjacent circles "-00-"
yin positions analogous to the em generators of FIG. I there is
shown a seven section DC machine. The c~nplete armature winding
arrangement comprises eight separate winding elements, each
generally of the type 32, spaced 45 degrees apart. These eight
windings are designated 32(0), 32(45~), . . . 32(315). Each
armature winding element has a total of fourteen torque generators
(seven prows) with the third pair in the 32(0) winding designated
as consisting of an it part and a clue* part. As before, the
individual torque generating elements are associated only with the
radial portions of the armature winding elements. A fuller descrip-
lion of the modes of operation of the ccmmutatorless DC Tnachine 10
as both a motor and also as a generator is provided hereinbelow.
Referring now Jo FIG. 4, there is shown half of a detailed Yen-
tidal cross-section of the stators assembly 14 of FIG. 1. The assembly
14 is pictured as c~nprising a plurality of stators flanges 22
assembled within the cylindrical, longitudinal yoke 24, all of
which is rapped by a pair of end yokes 26F and 26R. longitudinal
bolts (not shown) may be used to align and fasten the various come
pennants together in any conventional nunnery. By reference to FIGS.
PA, 5B~ PA, and 6B, in addition to FIG. 4, the stators flanges 22
art shown to be of two distinct types. These types are designated
a stators core flange 22C, and a stators plain flange 22P. The plain
type flange 22P of FIGS. PA and 5B is shown a generally disc-shaped,
-12-
and having a thickness at its inner periphery of "t ". The plain
flanges 22P further have a rip boss 44 at the outer periphery on one
side, and a centrally located Gore of radius "r ". The rim boss 44
has an axial extent approximately the same as the thickness "t "
and a radial extent very much less than the dimension "us" of the
flange 22P. Momentary reference to the overall DC macho of FIG.
1 shows that the central bore 46 has radius "r " slightly larger
than the radial dimension "rub" of the boss 38 shown in FIG. 3B,
allowing the rotor assembly 12 to rotate smoothly within the stators
assembly 14.
The core type flange 22C of FIGS. PA and 6B is shown as also
being generally disk-sha~ed,and having a thickness at its inner
periphery of "t ". The core flange 22C also has a rim boss OR at
its outer periphery on one side, and further has four radial pole
core projections 50 spaced at 90 degree intervals around its air-
cumference. The rim boss 48 extends over the pole core projections
50. Except for the presence of the core projections 50, the overall
configurations and dimensions of the core flange 22C are the same
as those of the plain flange 22P. On close assembly, these pole
core projections 50 for a pole core region 52 (its extent indicated
generally my the associated multiple headed arrows around which a
field core winding 54 is wound. Of the four projections shown in
FIG. PA, only one pole core region 52 is shown in FIG. 2. It is
to be understood that the four pole core configuration shown is
illustrative only, and that the actual number of poles to be used
in any particular DC machine is largely established as a matter of
design choice. Thus, DC machines according to the present invention
may contain more or less pole core projections, and may also be of
odd or even numbers.
A cylindrical stators core region 56 (its extent indicated
generally by the associated multiple headed arrows is formed by
the close assembly of the plain type and core toe stators flanges.
As with the pole core region 52, this g atop core region 56 is not
a separate component as such, but is defined largely in terms of
its function. the function of the stators core region 56 is similar
aye
to that of pole shoes in a conventional DC machine. Additional
pieces of magnetic structure such as an end piece 57 may be included
as necessary to suitably shape the magnetic circuit paths. Further,
in selected alternate embodiments of the stators assembly 14, supple-
Monterey plain flanges 22P* (indicated in dotted lines as slightly modified, i.e., not having significant rim bosses 44) may be in-
eluded at the forward and rearward ends of the stators assembly to
produce a stators flange/rotor flange interleaving arrangement wherein
all rotor flanges 16 are surrounded on both of their planar sun
faces my stators flanges of the types 22C and/or 22P and/or 22P*.
In the embodiment of FIG. 4, separate field coils would be
mounted on each of the four pole core regions (only one shown) and
the ends of each of these coils are brought out to the DC machine
terminal board (not shown) for mutual and external electrical con-
sections. A simplified electrical schematic of the stators field windings is shown in FIG. 10 as four identical sets of field windings
54 connected in series and brought out to a pair of terminals " "
and "En"- The particular arrangement of field windings is largely
- determined by the design requirements a given machine is a responseto. The number of individual coils (such as the single field core
winding 54) on each pole core and their specific winding and inter-
connection pattern is dependent on the type of DC machine contem-
plated. Illustrative DC machine types include separately excited,
shunt excited, series excited and compound excited. Audi, field
control rheostats external to the DC machine (not shown) may be
employed as part of the excitation source applied to the " "/" "
terminals. While toe arrangement of field windings is a matter of
design choice, it is significant to observe in the embodiment of
FIG. 10 that the resulting magneto motive force (hereinafter mmf),
as depicted by the arrow symbols "-I ", are unidirectional. In
this case, all four "--I " are directed radially inwards to pro-
dupe the desired magnetic circuit paths, as is detailed below.
Based on the structures detailed above, a description of
the operating principles of the DC machine both as a DC motor and
as a DC generator is now facilitated. While the rotor and stators
electrical circuits are comparatively straightforward, the magnetic
circuits of the present invention contrast significantly with the
magnetic circuits ox the conventional DC machine, and warrant
special attention. Referring now to FIG. 11, there is shown half
of a typical magnetic circuit and the resulting flux paths of the
basic embodiment DC machine shown in FIG. 1. To provide improved
emphasis on the magnetic circuit paths of interest, a number of
symbols have been omitted from this drawing, but it is to be under-
stood that FIG. 11 represents the same seven-section DC machine
described in connection with FIGS. 1, 2 and 4.
In operation, all of the yield coils of the DC machine
are excited from a suitable DC source such that the my produced
by the field coils can be made to be directed either radially
inwards or radially outwards depending on the direction of the
currents in the coils. The direction chosen does not matter to
establish the operating principles. In the present description,
all of the field coil excitations are chosen so as to produce mmf's
directed radially inwards such that all of to pole cores have
radially inward directed magnetic fluxes. This flu gets distributed
as shown in the stators core to all the stators flanges, and takes the
two major paths indicated by two sets of flu arrows - F _ and
I - to axially cross the air gaps 58 between contiguous stators
and rotor flange surfaces over their overlapping portions. There-
after as shown by the arrows, the flux paths enter the rotor
flanges; reach the armature core; and travel allele towards the
front (or rear of the machine towards the encase. The flux paths
then cross the two very thin air gaps between 38' and 38" to reach
respectively, the end yokes 26F and 26R; whereupon thy flux travels
radially outwards in the two end yokes; then turns to travel
axially inward towards the pole in the longitudinal yoke 24; and
finally returns to the pole core regions 52, thereby completing the
magnetic circuit. Because of the symmetry of parts, there are two
it
symmetrical magnetic circuit paths beyond the pole cores. The for-
warmly extending circular path (towards 26F) making a clockwise pat-
tern indicated generally by its arrow ; and the rearwardly
extending circular path (towards 26R~ making a counterclockwise
pattern indicated generally by its arrows I - .
he flux in the air spaces 58 sandwiched by the rotor and
stators flanges (hereinafter called the air gap or air gap flux)
has the following features of importance. Firstly, the air gap
fluxes are substantially all axially directed. Secondly, the
air gap fluxes leave the stators flange surfaces substantially
normal to the surfaces, and Roth the forwardly and rearwaxdly
facing surfaces of all stators flanges act as if they are flux
emitter surfaces. idly the air gap fluxes enter the rotor
flange surfaces substantially normal to those surfaces, and both
the forwardly and rearwardly facing surfaces of all the rotor
flanges (except for the end flanges) act as if they are flux
collector surfaces. As will be described below, the magnetic
flux incident upon the two planar surfaces of any one rotor flange
are oppositely directed - i.e., Roth fluxes are interiorly directed
Gore detailed description of the magnetic circuits and
flux paths is facilitated by reference to FIGS. 12 and 13 which
show enlarged portions of a typical rotor/stator interaction
areas extracted from FIG. 11. In both FIGS. 12 and 13, the path
DEFGHI shows a typical portion of the armature winding element.
(These capital-lettered conductor paths are generally the same
as those indicated in lower-case letters in FIG. 7). As seen,
lengths EN and GO have radial runs, while lengths DE, FOG, and I have
axially runs. It it significant to note that the interaction
it linkages) of the magnetic flux with the axial Hun portions
(DE, FOG, and HI) is assent, because the magnetic flu and these
conductor lengths are parallel, and/or lie in fringe magnetic
field regions. Over the radial run portions (i.e., EN and GO
the length of the conductor lying in the magnetic field air gap
58 has full interaction Linkages with the air gap magnetic flux,
because the two are normal to each other. The above flux/conductor
-16-
orientations are typical, and extend over the full run of each
armature winding element. The same relationships obtain for all
other winding elements in a complete armature winding arrangement
Considering now operation of the DC machine 10 as a comma-
tutorials DC motor, let all the field coils be excited to establish
a magnetic field as shown in FIG. 12. Note that the flux path
designated err - divides further into two paths in the stators
flanges to enter each rotor flange from opposite directions. Thus,
the rotor flange within the conductors EN and GO experiences front-
to-rear directed flux from the stators flange emitter surface closest
to the EN surface; and that the same rotor flange experiences rear-
to-front directed flux from the stators flange emitter surface
closest to the GO surface. jet the forward slip ring 30F of the
machine be connected to a suitable external DC source (through a
stating rheostat, not shown) positive terminal, and the rearward
slip ring 30R be connected to the negative terminal. The direction
of the resulting armature current is shown by motor current arrows
- I . The interaction of the air gap magnetic flux with the
orthogonally oriented current carrying conductor portions causes
mechanical forces on the conductor. Applying Flings Left-Hand
Rule (the motor rule) and looking at the machine from the rearward
end of the shaft, the mechanical forces on the conductors EN and GO
are both in the clockwise direction. These forces constitute a
clockwise torque T on the rotor assembly 12. This condition extends
over the particular armature winding element 32, and further over
the complete armature winding arrangements, for the portions of the
conductors similarly disposed. All of these forces being
additive, a large resultant torque is created on the rotor
assembly thereby producing the desired operation as a DC motor.
on operation, the commutator less DC motor of the present invention
exhibits the usual rotary device properties such as counter em,
losses, and the like.
Considering operation of the DC machine 10 as a commutator less
DC generator, let all the field coils again be excited to establish
a magnetic field as shown in FIG. 13 identical to that of FIG. 12).
Ill the rotary shaft 18 be coupled to a prime mover to cause clock-
I.,
I
-17-
wise rotation looking from the rearward end of the DC machine.
Consider the interaction of the air gap flux as before with the now
rotating active armature conductor portions EN and GO. Applying
Fleming's Right Rand Rule (the generator rule the conductors
experience dynamically induced ems, the directions of which are
from H to G and from F to E as shown by the induced current arrows
I in FIX. 13. These ems are directly additive in thy
winding element. This condition extends over the particular armature
winding element 32 and for the complete armature winding element
arrangements, for the conductors similarity disposed. All other
portions of armature conductors disposed substantially differently
from EN and GO do not produce any induced ems. Thus the DC machine
10 operates as a DC generator and produces the resultant em between
the two slip rings, the onward slip ring attaining positive polarity,
and the rearward slip ring attaining negative polarity. The DC
machine functioning either as a motor or as a generator can be
loaded as in conventional DC machines, and control similar to those
used in conventional DC machines may be incorporated into it. Further,
the DC machine can be built for different types of excitation to
obtain different characteristics as in conventional DC machines.
In summary, it is noted that basic commutator less DC machines
acting either as motors or as generators may be realized using
the teachings of the present invention, which simultaneously
exhibit the following desirable properties. Commutators of all
types are specifically absent thereby completely eliminating
the full range of electrical problems they present, and further
eliminating the design limitations they conventionally impose
on rotating machines. Direct current exists in all of the
armature winding conductors, and slip rings only are used as
electrical inputs or outputs from the machine. Thy stacking of
any number of separate disk (both rotor and stators sections
along with the straightforward armature winding arrangements,
permits the realization of commutator less DC machines for
operation at almost literally any voltage or current desired.
-18
An Improved Embodiment
Referring now to FIG. 14, there is show an improved embo-
dominate of a commutator less DC machine according to the present
invention. FIG. 14 shows half of a vertical cross-section through
a multiple disc, tandem configured, commutator less DC machine 400.
Brief reference to FIG. 1 shows that the tandem configuration of
FIG. 14 contains largely the same structural elements as the simply
configured (basic embodiment of FIG. 1. Thus, the structural
elements of FIG. 14 which perform substantially the same functions
as those of FIG. 1 are correspondingly numbered (with differing
prefixes) as an aid to clarity.
Briefly, the improved DC machine 400 is shown as comprising
three rotor/stator units in tandem - designated as a central machine
unit 100, a forward end machine unit 200, and a rearward end machine
unit 300. Taken by to selves, each of the three tandem units
functions generally the same as the single unit of the basic embo-
dominate. However, the addition of the two end units produces new
and highly useful operating modes which give rise to a marked imp
provement in machine operation as is described below. While
correspondingly numbered, the various structural elements are
designated by differing leading digits which designate their distinct
positions within the overall DC machine 400. For instance: central
shaft 118 corresponds functionally to central shaft 18; and pole
core region 152 of the central unit 100, plus pole core region 252
of the forward end unit 200, and pole core region 352 of the rearward
end unit correspond functionally to pole core region 52. However,
as will be described, end flanges 402F and 402R do not correspond
to end yokes 26~ and 26R.
In FIG. 14, a hollow cylindrical yoke 124 houses stators asset-
bites 114, 214, and 314 which are functionally associated with the
central, forward, and rearward machine units respectively. Each of
these assemblies comprises spaced apart stators flanges 122, 222 and
322, which are shaped and assembled to create pole core regions 152,
252, and 352, as well as stators core regions 156, 256 and 356 - when
I
--19--
energized by their respective field core windings 154, 254 and 354.
A pair of circular nonmagnetic end flanges 402F and 402R are affixed
to the forward and rearward ends respectively of the cylindrical yoke
124 to form an enclosed compartment. me ends of the central shaft
118 pass through the end flanges 402F and 402R, and are suitably no-
twined and fitted with bearings snot shown) m the regions 404F and
404R by well-known and conventional means.
The central shaft 118 (which is concentric with a machine
axis of rotation 120~ carries three flanged rotor assemblies 112,
212, and 312, which are functionally associated with their cores-
pondingly positioned central forward and rearward machine unit asset-
bites. Each of these rotor assemblies comprises spaced apart
rotor flanges 116, 216 and 316, on which are formed armature
winding elements 132, 232, and 332 respectively. Each rotor assembly
further comprises a concentric pair of slip rings FRY, 230F/
230R and FRY. As before, these armature winding elements
are shown in cross-section, and each is terminated at its forward
and rearward ends to its correspondingly lettered slip ring.
(i.e., the forward end of armature winding element 132 is terminated
on slip ring 13aF, and the rearward end of armature winding element
132 is terminated on slip ring 130R; similarly for armature winding
elements 232 and 332.
In the improved embodiment of FIG. 14, the central unit 100
is shown as having five illustratively) longitudinally stacked
rotor flanges of thy type 116 which produce an armature core region
142, while the forward end unit 200 is shown as hazing three
(illustratively) longitudinally stacked rotor flanges which produce
an armature core region 242. Similarly, the three rotor flanges
of rearward end unit 300 produce an armature core region 342. On
close inspection it is seen that the actual shapes of a number of
rotor and stators elements of the basic and improved embodiments
are slightly different. For example, cross-sectional views of the
bases of elements 116 (plus 216 and 3161 of FIG. 14 are different
from the bases of the elements 16 of FIG. 1. These (plus others)
are minor structural changes permissible within the overall machine
I
I
designs contemplated. Other than the one exception mentioned above,
the magnetic properties of the elements of both the basic and the
improved embodiments are the same. On a unit by unit basis, the
operating principles of the central lit 100 and end units 200 and
300 are identical to those previously described in connection with
the basic embodiment of FIGS. 1-12. This is so with respect to
operations as both a Gcmmutatorless lo motor and as a c~m~utatorless
DC generator. however, when the three units are positioned in tandem
on a common shaft within a common housing, significantly improved
performance in all operating modes is realized. This is primarily
due to the more effective magnetic circuit which now links the
three machine units together. Whereas the basic embodiment included
air gaps between the rotor bosses (elements 38' and 38") and the end
yokes (elements 26F and 26R) as part of the magnetic flux paths
(all as shown in FIG. 11), to present improved embodiment has no
such lousy gaps. Instead, the armature core regions 242 and 342 do
not extend far enough along the shaft 118 to mate with the end
yokes 402F and 402R, thereby producing an effective break in the mug-
netic circuit path at regions 406F and 406R. The two end machine
units 200 and 300 therefore experience the overall machine flux paths
as now described.
Referring to FIG. 15, there it shown half of a simplified
magnetic circuit and the resulting flux paths of the improved embo-
dominate of the DC machine 400. To emphasize the magnetic circuit
paths of interest, a number of element designations have been
omitted from this drawing, but it is to be understood that FIG. 15
represents the same eight-section, three-unit DC machine of FIG. 14.
In operation, the field core winding 154 of the central unit 100
is energized so as to produce mmf directed radially inward, giving
rise to the inwardly directed central magnetic flux, indicated by
the arrows - C . The field core windings 254 and 354 are ever-
gibed so as to produce mums directed radially outward giving rise
to the outwardly directed magnetic flux paths indicated by the flux
arrows - I for the forward end unit 200, and I - the rear-
ward end unit 300. The forward end unit flux arrow - Foe is
.-,,
147
shown in FIG. 15 as directed upwards through the stators core region
256, and thereafter to the rearward (towards thy right in the
cylindrical yoke 124. The rearward end unit flux arrow I
is shown as also directed upwards through the stators core region
356, and thereafter pharaoh do (towards the Lotte in the cylindrical
yoke 124. Due to the magnetic circuit breaks at 406~ and 406R and
the nonmagnetic materials of the end flanges 402F and 402R, the
resulting overall flux paths are distributed as shown in two air-
cuter paths. The forward flux - I passes via its stators core
region 256 and then joins with the central flux - C in a
clockwise fashion; and subsequently passes back through its aroma-
lure core region 242 thereby completing the magnetic circuit.
Similarly, the rearward flux I - passes via its stators core
region 356 and also joins with the central flux - I , but in a
counterclockwise fashion; and subsequently pauses back through its
armature core region 342 to complete its magnetic circuit.
Preferably, this two-looped magnetic circuit is arranged such that
the forward and rearward end units are of the same magnetic sizes,
and the sum of the two equals the magnetic size of the central unit,
so that the two end units share equally the magnetic flux handled
by the central unit. Clearly, however, other relative sizes may
also be used between the three machine units as required to meet
varying operating requirements of the overall DC machine 400.
Examination of the flux directions in the two end units -
US in the rotor flanges; air gaps; stators flanges; stators cores;
and pole cores - reveals that the flux direction-in all of these
are reversed from those in the corresponding portions of the
central unit. So, while the central unit 100 functions identically
to that of the basic embodiment the two end units function the
same but with opposite polarity/senses. In effect then, the improved
embodiment has merely distributed its active portions in a more
advantageous manner, and thereby has eliminated the magnetic circuit
path losses by fully utilizing all major legs of the flux path.
to
I
Operation of the ccmmutatorle~s DC machine 400 as a tandem
configured motor is now described with reference to PIGS. 16-19;
plus brief references to selected fiches associated with the basic
embodiment. FIG. 16 shows a perspective drawling of a composite aroma-
lure winding arrangement 408 hazing eye following components four armature winding elements I 90, 180, and 360 9 circus-
ferentially spaced around the rotor flanges; three machine units,
forward, central and rearward; and a total of eleven-sections,
distributed as three sections each for the two end units and five-
sections for the central unit. Expressed in terms of previously used designations, the composite armature winding assembly 408 con-
sits of at least three (one per unit) complete armature winding
arrangements of the type shown in FIG. 7. Expressed quantitatively,
the composite may be described as a "4x3/5/3." The four armature
winding elements for the forward unit 200 are designated as 232(0 ,
232(909, 232(180 I; and 232(270 - and are shown to be connected
in parallel and terminated on slip rings 230P and 230R. The dusk
nations of the armature winding elements of the central unit 100
and rearward unit 300 (designations not shown to eliminate drawing
clutter) are similarly implied. The mature winding elements for
the machine units 100 and 300 are shown as terminated in their
respective slip ring pairs of FRY and FRY. Several
aspects of this composite armature winding æ rangement 408 are
illustrative only. Firstly, the number of armature winding elements
per unit are shown as four, but any number may actually be employed
depending upon. design criteria. Secondly, the number of sections
are shown as eleven - distributed as 3/5/3 over the three units -
but any number may actually be employed, also depending on design
criteria. However, for the tandem principle to ye optimized, at
least two machine units are required; and in a preferred embody-
mint, three are æ ranged in tandem as shown.
FIG. 17 shows a simplified electrical schematic of the equiva-
lent composite armature winding arrangement of FIG 16 operating as
a motor. Brief review of thy description ox motor operation for the
basic embodiment associated with F~CS. 7 and mull serve to facile-
9L7
-23-
late the present description. As before, torque is produced only
in the radial portions of each armature winding element again
depicted as a pair of adjacent circles " Ox-"). A pair of such torque
producers are designated as en and go for the second from left
section of the armature winding element 132(0 if. the central unit
100. Thus, FIG. 17 shows an array of 44 pairs of torque producers
grouped together as 3x4=12 for each of the end machine units, and
4x5=20 for the central unit 100.
FIG. AYE and 18B show simplified electrical schematics of a
It composite stators field core winding 410 suitable for use with the
improved DC machine of FIG. 14. Four identical sets of field
windings 54* are confected in series (illustratively) and are
energized by a DC source by a pair of terminals " " and "En".
Each of the four windings 54* in turn comprise a field core winding
for each of the three machine units, wound in the proper sense so
as to produce the flux patterns of FIG. 18B. By brief reference to
the flux patterns of FIG. 15, recall that the required mmf's are:
radially outward for the forward and rearward end units 200 and 300
shown by the - F* and I - flux arrows, and radially
inward for the central unit lQ0, shown by thy - I flux arrow.
The number of individual field core windings used on each pole
core (in this case four), and the manner of interconnecting the
windings (in this case all in series are factors which are determined
by design convenience and requirements. Thus, the total number
of field core windings (a total of twelve - four per machine unit
times three units) and various series/parallel interconnection schemes
are considered design choices; the primary criteria being the
production of properly oriented flux of the proper magnitude in the
air gaps between the spaced apart rotor and stators flanges.
FIG. 19 provide a visual summary of the primary operating
parameters of the DC machine 400 while it is functioning as a
tandem commutator less DC motor. Armature current is applied to the
three machine units by a number of molar current arrow I
as follows: current into the forward end unit 200 via slip ring
35 230R, out via slip ring 230F; into the central unit 100 via the
-2~1-
slip ring 130F and out via the slip ring 130R; and into the rearward
end unit 300 via the slip ring 330R; and out via slip ring 330F.
(The motor current arrows ---O*- of FIG. 19 are functionally
analogous to the motor current arrows I of FIG. 12, but of
course, not necessarily of the same magnitude; and similarly for
the flux arrows - I and - I ; and I - and I - .
upon applying a DC source via a pair of terminals I' Q and
as shown in JIG. 17, and further upon energizing the composite field
coils of FIG. AYE to produce the flux orientations as shown in
FIG. 18B and FIG. 15, operation as a commutator less DC motor results.
As before, a straightforward application of Fleming's Left-Hand Rule
for motors applies, and describes the action. Consider one part-
cuter portion of the air gap designated as 258 as typical. In that
portion of the armature winding element 232, armature current is
directed radially inwards. The air gap portion of the flux - F*--
vector is directed rearward left to right) giving rise to a torque
(into the plane of the paper) producing clockwise rotation as
viewed from the rearward end of the central shaft 118. Thus, a net
torque "T" is exerted via the shaft 118 responsive to the series
aiding effect of all active portions of the rotor/stator air gaps.
Operation of the commutator less DC machine 400 as a tandem con-
figured generator is now described with reference to FIGS. 16, 18,
20 and 21; plus brief reference to selected figures associated with
the basic embodiment. FIG. 20 shows a simplified electrical schematic
of the composite armature winding arrangement of FIG. 16 operating
as a generator. Brief reference to the description associated with
FIGS. 7 and 9 will facilitate the present description. As before,
voltage is induced only in the radial portions of each armature
wading element (again depicted as a pair of adjacent circle/dot
symbols "-OX-"). A pair of such em generators are designated as "e-f"
and "g h" for the second from left section in the central unit
100. Thus, FIG. 20 shows an array of 44 pairs of em producers
grouped together as twelve each for the forward and rearward end
units 200 and 300, and twenty for the central unit 100.
Lo
-US-
FIG. 21 provides a visual Syria of the primary operating
parameters of the DC machine 400 while it is functioning as a tan-
dim commutator less DC generator. upon energizing the composite
field coils of FIG. AYE, as for motor operation, and applying
clockwise (as viewed from the machine rearward end) rotation
to the shaft 118, operation as a cGmmutatorless DC generator
results. A straightforward application of Fleming's Right-Hand
Rule for generators applies, and describes the action. By
selecting a representative portion of the air gap, designated 258
as before, we note that the air gap portion of the flux F* _
vector is directed rearward (left to right), and that the rotation I
causes the rotor flanges 216 to move clockwise (into the plane of
the paper). Thus, voltage is induced in the radial portion of the
armature winding element in the gap 358, giving rise to conventional
currents as indicated by a number of current arrows {I* .
The net voltage produced by all active rotor~stator regions in the
three tandem machine units produce generator currents as follows:
current leaves the forward end machine unit 200 from slip ring
230R; leaves the central machine unit 100 from slip ring 130F; and
leaves the rearward end machine unit 300 from the slip ring 330R.
Interconnection of the outputs from the three tandem machine units
to be series aiding produces a highly effective commutator less DC
generator embodying the principles of the present invention.
As with the basic embodiment, the improved DC machine lung-
toning either as-a motor or as a generator can be loaded the same
as conventional DC~machines; and well-known controls similar to
those used in conventional DC machines may be incorporated into
it. Further, both the basic and the improved DC machines can be
built for different types of excitation to obtain different kirk-
teristics as in conventional DC machines.
In summary, it is noted that the commutator less DC machines acting either as motors or as generator, and configured as either
basic or improved embodiments, may be realized using the teachings
of the present invention, which simultaneously exhibit the following
desirable properties. Commutators of all types are specifically
,.
47
26~
absent, thereby completely eliminating the full range of electric
eel problems they present, and further eliminating the design limit
stations they conventionally impose on rotating machines. Direct
current exists in all of the armature winding conductors, and slip
rings only are used as electrical inputs or outputs from the machine.
me stacking of any number of separate disk (both rotor and stators
sections, plus the use of various types of field core winding
arrangements, and various tandem combinations of machine units,
permits the realization of c = utatorless DC machines for operation
at almost literally any voltage/current/torque/speed range desired.
Although the invention has been described in terms of basic
and improved embodiments and selected preferred alternates thereof,
the invention should not be deemed limited thereto, since other
embodiments and modifications will readily occur to one skilled
in the art. For example, while the embodiments described show
the rotor structure as rotating within stationary stators structure,
as is conventional; it would be merely a design choice to embody the
disclosed inventive concepts into a machine wherein the stators struck
lure were rotated around stationary rotor structure. Also, arranging
the improved embodiment into a 4x3/5/3 configuration is merely a design
choice, illustrative other choices such as 4x3/6/3 or 8xlO/20/lO
would be equally feasible. And, the present descriptions have been
facilitated by assuming that the flux linkages in the non radial portions
of the armature winding elements are Nero. This may not necessarily
be the case for all configurations. Leakage flux from stators to rotor
linking the axial run portions may in some cases produce electromagnetic
results that are additive to the outputs of the machine embodiments
working either as motors or as generators. It is therefore to be under-
stood that the appended claims are intended to cover all such modifica-
lions and variations as fall within the true spirit and scope of the
invention.
