A PLANETARY PUSH-PULL ELECTRIC MOTOR
FIELD OF THE INVENTION
The present invention is related to the field of electric motors, and in particular
to a planetary push-pull electric motor whose operation is based on the dynamics of
the physical interaction under a magnetic field between a stator and a planetary rotor
whose axes of rotation are eccentric in relation to each other.
BACKGROUND OF THE INVENTION
Electric motors are widely used in our modern life: in industrial applications;
in land vehicles, such as cars, trucks, and mobile machinery; in airplanes and other
airborne vehicles; in military applications; in mechanical and electrical devices used
in medical technology; and in home appliances.
As the demand for electric motors has increased over the years — and
continues to do so ~ many types of motors have been developed to satisfy the wide
variety of applications and needs of our technologically oriented society. In the field
of electric motors, for example, we can find high- and low-speed rotary motors,
torque motors, linear motors, nanomotion motors, and many more, each developed to
meet a specific purpose or purposes.
Since the invention of the first motor concept about 180 years ago, the
construction of electric motors has been based on the concept of an internal, rotating
body called a rotor and an outer, stationary body called the stator, where each was
concentrically located in respect to the other. The electromagnetic interaction between
these two elements produces S-shaped magnetic lines which are then induced to be
straightened, and the resultant semi-tangential vector results in the production of
rotational moment.
In consideration of the weight-to-power ratio of lightweight electric motors, it
is understood that a small, lightweight motor makes a trade-off due to its size in that
the motor velocity is generally of a very high speed if the motor is small, and
consequently, a high-reduction gear box is needed to obtain the desired speed.
In many applications gearboxes need to be used to engage with the electric
motors, either to reduce the speed and/or to increase the moment, or to convert a
rotary movement into a linear movement. In practice, a parallel gear train gearbox, a
planetary gearbox, or harmonic drive reducer can be used to reduce or increase rotary
motor speed and/or moment. Alternatively, a screw and nut, or rake and pinion, can
be used to convert rotary movement into linear movement.
However, gearboxes that are connected to electric motors suffer from a few
disadvantages. Gearboxes are normally connected to electric motors in serial and this
increases the total assembly length and or diameter of the combined unit. The weight
of gearboxes is generally high. Furthermore, the add-on gear assembly tends to be
noisy, expensive, and of low efficiency.
Thus it would be desirable to provide an innovative electric motor that
overcomes the above-mentioned disadvantages and improves on the current concept.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to overcome the
disadvantages and limitations of prior art systems and to provide an improved electric
motor comprising a planetary push-pull electric motor (hereinafter, "PPPEM") and
based on the interaction, when operated, between a stator, configured with a series of
electromagnets arranged radially around the stator axis, and a planetary rotor,
disposed eccentrically to the stator.
It should be understood that the use of the term "PPPEM" is meant to convey
the general idea that a planetary push-pull electric motor (PPPEM), when activated,
produces output power by planetary rotor rolling motion in two major ways: by offset,
pivotal motion of a gear-type ptanetary rotor in dynamic relation with a stator ringgear,
or, alternatively; offset rotation of a friction-type planetary rotor in friction to a
ring- stator. Both types of planetary rotors are impelled to pivot by an electromagnetic
force applied at a sequential series of moving, mesh pivot lines (see orthographic view
of item 60 in Fig. 24). The PPPEM can be activated by either a magnetic attraction
(pull) or a repulsion (push) force, depending on the particular embodiment of the
invention described herein. Unless otherwise stated (and intended as only one or the
other), PPPEM refers to the use of both push and pull electromagnetic forces in the
operation of the present invention.
It is another object of the present invention to provide a PPPEM having a
planetary rotor comprising a soft, ferromagnetic core whose stator electromagnets
induce only a pull magnetic force.
It is yet another object of the present invention to provide a PPPEM having a
radial magnet-ring, planetary rotor.
It is a further object of the present invention to provide a PPPEM having a
tubular, radial-magnet planetary rotor.
It is still another object of the present invention to provide a planetary push
electric motor having a radial magnet-ring, planetary rotor.
It is another object of the present invention to provide a PPPEM where the
stator magnetic forces radially push and/or pull a planetary rotor axis upon an outer
mesh pivot contact line.
It is yet another object of the present invention to provide a PPPEM having a
radial magnet-ring rotor operable utilizing both push and pull electromagnetic forces
to produce the planetary rotation of the rotor, which is integral to a rotor gear, upon a
stator ring-gear, resulting in a torque at a moving, mesh pivot contact line formed
between the stator and rotor gears.
It is still another object of the present invention to provide a PPPEM having a
series of stator electromagnets encased in soft, ferromagnetic cases forming a core so
as to concentrate magnetic flux from the magnetic poles of each encased
electromagnet towards the active face of each of a series of holding electromagnets in
closest proximity to the planetary rotor when the PPPEM is activated.
It is still another object of the present invention to provide a built-in planetary
mesh where the stator is a magnet ring-gear and the rotor is a planetary gear.
It is another object of the present invention to provide a PPPEM free of the
need for add-on gear boxes.
It is yet another object of the present invention to provide a PPPEM having a
built-in, semi- dual-stage planetary gear.
It is still another object of the present invention to provide an eccentrically
floating axis, radially loaded from the planetary rotor toward the stator.
It is a further object of the present invention to provide a planetary pull electric
motor having a zero backlash mechanism loaded by the pull magnetic forces between
the stator and the rotor.
It is still a further object of the present invention to provide a PPPEM having a
zero backlash mechanism loaded by springs that radially force a planetary rotor gear
against a stator gear.
It is another object of the present invention to provide a PPPEM having a
built-in, oversized, planetary rotor gear.
It is yet another object of the present invention to provide an almost zero air
gap, high-efficiency PPPEM.
It is a further object of the present invention to provide a PPPEM with an
eccentric planetary rotor for specific applications comprising only a sector of a full
PPPEM
It is still another object of the present invention to provide a PPPEM with an
eccentrically mounted, planetary rotor that operates with push-pull electromagnets in
an exterior ring stator.
It is still another object of the present invention to provide a PPPEM with a
planetary rotor for gearless control of a fixedly attached, rotatable lead screw shaft
provided with a laterally movable nut for attachment to devices requiring a
mechanism for simple back and forth movement.
Therefore there is provided a planetary push-pull electric motor (hereinafter:
"PPPEM") comprising:
a ring stator fixedly mounted on a central axis of the planetary electric
motor, wherein the central axis defines a ring stator centerline;
a planetary rotor arranged to be magnetically movable, rotatably mounted
on an eccentric rotor axis in respect to the ring stator centerline;
a series of electromagnets radially mounted about the ring stator centerline
for generating radial magnetic force upon the magnetic fields of the planetary rotor
when the series of electromagnets is activated,
a means for transferring rotation of the eccentric planetary rotor axis to
directly power an output shaft of the PPPEM .
wherein when the series of electromagnets is activated, radial push-pull
magnetic forces are generated, magnetically impelling the planetary rotor in proximal
radial contact with at least one electromagnet in the series such that the planetary rotor
pivots from one of the proximal tangential contact to an adjacent one in sequence,
effecting a continuous rolling motion of the planetary rotor about the eccentric rotor
axis and creating a rotary moment, such motion being translated into rotational
motion which, when applied to the output shaft of the PPPEM utilizing the rotation
transferring means, provides a source of power output from the PPPEM.
Further features and advantages of the present invention will be apparent from
the drawings attached and the description contained herein.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention with regard to the embodiments
thereof, reference is made to the accompanying drawings, in which like numerals
designate corresponding elements or sections throughout and in which:
Fig. 1 illustrates a typical, prior-art electric motor constructed with an
internally mounted stator and externally mounted rotor;
Fig. 2A shows a transverse, sectional view of a PPPEM with pul magnetic
poles constructed in accordance with a preferred embodiment of the present
invention;
Fig. 2B illustrates, in another view, the operation of the PPPEM from Fig. 2A
in accordance with the principles of the present invention;
Fig. 2C is an orthographic, partially sectional view of the major components of
the PPPEM from Figs. 2A and 2B;
Fig. 3 is an orthographic, partially cut-away view of yet another embodiment
of the present invention which provides a high gear-reduction ratio;
Fig. 4 is an orthographic, partially cut-away view of another embodiment of
the present invention which exhibits a low gear-reduction ratio;
Fig. 5 is an orthographic, partially sectional view of an alternate embodiment
of the present invention where the PPPEM comprises an external, eccentrically
mounted rotor ring-gear which meshes with an internal stator gear;
Fig. 6 is an orthographic, partially sectional view of yet another embodiment
of the present invention;
Fig. 7A is a partially cut-away orthographic view of an alternate embodiment
of the present invention showing a PPPEM whose externally mounted stator is
provided with a ring-gear larger in diameter than that of an internally mounted,
cylindrical rotor core coaxially fitted to a pair of oversized rotor gears which mesh
with the stator gear;
Fig. 7B is a sectional, axial view of the PPPEM from Fig. 7A showing the
arrangement of the radially mounted electromagnets;
Fig. 8A is an orthographic, partially cut-away view of the PPPEM from Fig.
7A shown together, by way of convenience only, with two types of anti-backlash
mechanisms (as detailed in Figs. 8B and 8C)
Fig. 8B illustrates an adjustable screw anti-backlash feature from Fig. 8A;
Fig. 8C illustrates an adjustable spring-type anti-backlash from Fig. 8A;
Fig. A is a sectional view of a PPPEM provided with tubular, radial magnetrings
in accordance with still another embodiment of the present invention;
Fig. 9B is a sectional, detailed view of the internal rotor from Fig. 9A showing
the tubular, radial magnet-rings;
Fig. 9C is a sectional view of the PPPEM from Figs. 9A/B showing an
exemplary manner of operation of magnetic forces to drive the rotation of an
internally mounted, planetary rotor in accordance with the principles of the present
invention;
Fig. 9D is a sectional view of the PPPEM from Figs. 9A/B/C showing radial
magnetic forces in operation in accordance with the principles of the present
invention;
Fig. 10 is a sectional view of a PPPEM, provided, by way of example, with a
mechanism to detect and measure planetary rotor speed and direction of rotation, cam
shaft-to-stator relative position, and rotor-to-stator orientation in accordance with the
principles of the present invention;
Fig. 11 is an orthographic, partially cut-away view of another embodiment of
the present invention showing a PPPEM with an eccentric, gearless, friction rotor;
Fig. 12A shows an orthographic, partially cut-away view of a friction PPPEM
in another embodiment of the present invention;
Fig. 12B is an orthographic, sectional view of the motor from Fig. 12A
showing details of the planetary rotor construction;
Fig. 13A is a sectional, cut-away view and an enlarged detail view of another
embodiment of a PPPEM provided with radial springs and tubular, bearings elements
to promote zero backlash;
Fig. 13B is a detail view of the action of a typical, radial compression spring
in aiding positive meshing between the gear teeth of a rotor gear and the stator ringgear
as shown in Fig. 13A;
Fig. 14 is an orthographic, sectional view of a PPPEM, in another embodiment
of the present invention, which utilizes a planetary rotor having flexible couplings to
realign the eccentric rotor output shaft to be coaxial with the stator axis for direct
power transfer through an output shaft;
Fig. 15A is a detailed, orthographic view of a holder-encased electromagnet
with an E-shaped profile constructed in accordance with another embodiment of the
present invention.
Fig. 15B is a sectional view of a PPPEM incorporating a series of single,
encased electromagnets from Fig. 15A, radially disposed within an externally
mounted stator;
Fig. 15C is an orthographic view showing the details of the ring stator with a
series of encased, E-shaped profile electromagnets from the PPPEM of Fig. 15B;
Fig. 16 is a sectional view of yet another embodiment of the present invention
comprising a PPPEM with an internally mounted, planetary rotor rotatably attached to
an eccentric, rotatable camshaft, and an externally mounted stator kept at a minimal
distance from contact with the planetary rotor;
Fig. 17A is an orthographic view of a prior art motor connected to a lead
screw shaft through a connection to a gear in a prior-art gear box;
Fig. 17B is an orthographic, partially cut-away drawing of a PPPEM
constructed with a gearless planetary rotor for direct operation of a ead screw shaft,
in accordance with the principles of the present invention;
Fig. 18A shows a general schematic view of a typical prior art, U-shaped
holding electromagnet;
Fig. 18B shows a general schematic view of a typical prior art, E-shaped
holding electromagnet;
Figs. 19A and 19B illustrate a typical two-step operation of a PPPEM having a
series of U-shaped profile cores and constructed in accordance with the principles of
the present invention;
Figs. 20A and 20B illustrate a typical two-step operation of a PPPEM having a
series of E-shaped profile cores and constructed in accordance with the principles of
the present invention;
Figs. 21A and 21B illustrate the front and back faces, respectively, of a prior
art ring magnet showing the opposite polarities of each face which are axially
oriented.
Fig. 22 shows a cross-sectional, orthographic view of another embodiment of
the present invention;
Fig. 23 is an orthographic, partially sectional view of still another embodiment
of the present invention;
Fig. 24 is an orthographic, sectional view of a gearless PPPEM in a further
embodiment of the present invention;
Fig. 25 is an orthographic, partially sectional view of yet another embodiment
of the present invention; and
Fig. 26 is an orthographic, sectional view of a preferred embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the drawings, Fig. 1 shows a general schematic overview of
a typical, prior-art electric motor 20 provided with an internally mounted stator 22
having electromagnetic coils 12, 14 and an externally mounted rotor 24 comprising
alternating adjacent magnetic poles marked North (N) and South (S). The axes of both
rotor 24 and stator 22 are coaxial at point 30 and output to a drive shaft (not shown) is
directly along the same axis at point 30.
When prior art electric motor 20 is activated, South (S) magnetic poles at
electromagnet coils 14 of stator 22 each attract the nearest North (N) magnetic pole on
rotor 24, attempting to "pull" the North (N) poles of rotor 24 closer to their nearest
oppositely-charged counterparts on stator 22 in accordance with the physical principle
of opposite magnetic poles attract. When polarity is reversed, North (N) magnetic
poles at coils 12 operate in a similar manner with their oppositely-charged
counterparts on stator 22.
The lines of pulling magnetic force are indicated by S-shaped arrows 26. The
S-shaped arrows 26 attempt to straighten, since magnetic lines tend to move in the
shortest possible paths, thus causing rotor 24 to rotate around a fixed, common central
axis 30 between rotor 24 and stator 22 and impelling rotor 24 to rotate in a clockwise
direction as indicated by arrow 32.
A Hall Effect sensor 34 is provided in proximity to the rotor 24 for measuring
magnetic flux when prior art electric motor 20 is operated.
Fig. 2A shows a sectional view of a PPPEM constructed in accordance with a
preferred embodiment of the present invention.
PPPEM 36 comprises: an externally mounted stator 38 having a stator ringgear
40, a series of radially mounted electromagnets 42 surrounded by and housed
within a stator envelope 44. PPPEM 36 further comprises an internally mounted
planetary rotor 46 having a planetary gear 48. The axis of PPPEM 36 is coaxial with
stator axis 52, i.e., in line with an output shaft (not shown), while the rotor axis 50 is
offset to a small degree, as indicated by eccentricity gap 54 (opposing arrows),
making planetary rotor gear 48 eccentrically disposed in relation to stator gear 40.
Note that, for clarity, both axes 50, 52 are indicated by enlarged points located
in the central area of rotor 46.
Power to an output shaft (not shown) is generated through the planetary
rotation of rotor gear 48 on a moving, pivot contact line 60 (shown as a point
indicated by dark arrow) to advance rotor gear 48 when magnetic pull forces are
activated during operation of electromagnets 42.
In a preferred embodiment of the present invention, both planetary rotor 46
and stator 38 are made of soft iron.
Rotor gear 48 and stator ring-gear 40 will not be in direct physical contact
with each other during operation, and gears 40, 48 are only for improvement of the
magnetic attraction between the gears 40, 48 by controlling and optimally reducing
the air gap between stator 3 and planetary rotor 46 as the latter is impelled to move
sequentially from one mesh pivot contact line 60 to another (see Fig. 2B) under the
impetus of the activated magnetic force generated by stator electromagnets. An
additional set of planetary gears (not shown) having high-tensile strength is provided
to keep the almost no-contact condition between rotor gear 48 and stator ring-gear 40
and is the gear set that produces and transfers torque to a motor output shaft (not
shown).
Fig. 2B illustrates, in a sectional, axial view, the operation of the PPPEM from
Fig. 2A in accordance with the principles of the present invention.
When PPPEM 36 is activated, planetary rotor 46 integral with rotor gear 48 is
magnetically pulled toward stator ring-gear 40 and tends to pivot in a rolling motion
upon moving contact pivot line 60 (indicated with a small, dark arrow) at
electromagnet 42a (electromagnets 42k and 421 are not involved at this stage of
operation) in order to generate a rolling motion force upon rotor gear 48. The next
sequential and adjacent electromagnet 42b with its magnetic poles facing planetary
rotor 46 is shown marked with N (= North magnetic pole) and is activated to attract
and pull planetary rotor 46 and integral rotor gear 48 so that planetary rotor 46
continues its planetary rolling motion. Electromagnet 42c now assumes greater
control of the rolling motion of planetary rotor 46 due to the growing proximity to
rotor gear 48 which now rolls away from one pivot contact line 60 to the next one
(arrow 58), and so on in a continuous rolling motion to produce a high torque force
sufficient to drive an output shaft (not shown) of PPPEM 36.
In another mode of operation, planetary rotor 46 may be kept in a balanced,
steady state. Referring again to Fig. 2B, when PPPEM 36 is operated, magnetic forces
(indicated by N-S magnetic poles) from electromagnets 42k and 421 create moving,
potential contact pivot lines 64, 62 (shown by respective arrows), by attracting rotor
gear 48 towards them on one side of moving, mesh contact pivot line 60 between
rotor gear 48 and stator gear 40. Simultaneously, equal magnetic forces (shown as NS
magnetic poles) from electromagnets 42b and 42c also act on rotor gear 48 to attract
it towards moving, potential contact pivot lines 58, 56 (shown by respective arrows)
on another side of moving, contact pivot line 60, providing equilibrium between the
magnetic forces (shown as N-S magnetic poles) and thus maintain rotor 46 in a
balanced steady state for applications requiring a sensitive positioning control.
Fig. 2C is an orthographic, sectional, axial view of the major components of
the PPPEM from Figs. 2A/B showing details of the meshing of planetary rotor gear
48 with the stator gear 40 due to the action of a series of electromagnets 42a/b/c. ..k/1
radially mounted around ring stator 38. When electromagnets 42b and 42c are
activated together, planetary rotor 46 is impelled to revolve clockwise towards the
pull of magnetic forces (indicated by N-S magnetic poles) and away from
electromagnet 42a which has been deactivated. Rotor gear 48 moves in planetary
mesh upon stator gear 40 (as hereinbefore described) at a single stage ratio of about
1 : 10.
Fig. 3 is an orthographic, partially cut-away view of yet another embodiment
of the present invention, comprising a PPPEM having an externally mounted ring
stator; a two-step, internally mounted, planetary rotor with integral primary and
secondary step gears; and a gear ring integrally formed with an output shaft and
providing a high gear-reduction ratio.
PPPEM 66 comprises an externally mounted ring stator 38 housed in an
envelope 44, a series of electromagnets 42b/c arranged axially about ring stator 38
with integral stator gear 40. A two-step planetary rotor 68, whose secondary step-gear
76 is integrally formed with the larger, planetary rotor gear 70, is rotatable coaxially
along rotor axis 50.
This two-step-gear arrangement compensates for the eccentricity by returning
final rotational power output through the coaxial stator axis 52 of ring stator 3 and
output shaft 74, rather than through the eccentric rotor axis 50. Since output shaft
gear-ring 72, integrally formed with output shaft 74, directly meshes with secondary
step-gear 76, there is provided a high gear-ratio on the order, for example, of 1:150.
Fig. 4 is an orthographic view of another embodiment of the present invention.
PPPEM 78 comprises an externally mounted ring stator 38 provided with a series of
electromagnets, such as 42b/c, arranged axially, and an integral stator gear 40 about
which a primary planetary rotor gear 80 from rotor ring 82 revolves when PPPEM 78
is operated. At the same time, a planetary, output-shaft gear 84, which is integral to
output shaft 73, meshes with a secondary step-gear 86 to provide rotational motion to
output shaft 73 at a given ratio. Note that stator axis 52 is coaxial with the axis of
output shaft 73 for direct power transfer.
Fig. 5 is a general orthographic view of an alternate embodiment of the present
invention wherein the PPPEM comprises an external, planetary rotor ring integral to a
rotor gear, which meshes with an internally disposed stator integral to a stator gear.
PPPEM 88 is provided with an externally disposed, planetary ring rotor 90
integral to a rotor gear 92 eccentrically rotatable about a stator axis 52 to which stator
94 is fixed. Stator 94 comprises a series of electromagnets 42 arranged axially around
stator core 96. When PPPEM 88 is operated, electromagnets 42, which are angularly
located at about 90 degrees to pivot contact line 60, impel planetary rotor gear 92 to
mesh with stator gear 98 upon a temporary, moving, mesh pivot line 60 and to rotate
about stator 94 at eccentric rotor axis 50 in accordance with the principles of the
present invention. Output power is delivered through an output shaft (not shown)
connected to a stator shaft (not shown), both of which are in alignment with stator
axis 52.
Fig. 6 is a general orthographic view of another embodiment of the present
invention. PPPEM 100 comprises an internally mounted, centrally disposed stator 94
having a core 96 and provided with a gear 98 to mesh with a first inner gear 102 of a
middle-positioned planetary rotor ring 04 whose axis 50 is eccentric to stator axis 52.
Rotor ring 104 is provided with a second outer gear 106 which simultaneously
engages and meshes with an output-ring gear 108 of an externally mounted, output
ring 1 0 whose axis (not shown) is concentric with stator axis 52 so as to return the
eccentric rotational force to directly impel a drive shaft (not shown) when PPPEM
100 is operated in accordance with the principles of the present invention.
Fig. 7A is a partially cut-away orthographic view of an alternate embodiment
of the present invention.
PPPEM 114 comprises a relatively large diameter, oversized, externally
mounted stator 11 within stator envelope 118 and provided with a pair of stator ringgears
0. Integrally formed around supporting, round flanges 124 are a pair of
internal, oversized, relatively large diameter planetary rotor ring-gears 122. Rotor
ring-gears 122 have a diameter relatively greater than the diameter of rotor core 126.
A series of electromagnets 42 are arranged radially around stator 6 to impart
continuous rolling motion to planetary rotor 126 and rotor ring-gear 122 when
PPPEM 114 is operated. Rotor axis 50 is eccentric to stator axis 52 as indicated by the
offset gap 54.
It should be noted that a rotor planetary gear, which, in respect to
consideration of either moments, speed, or diameter-to-thickness ratio, could also
have a planetary mesh which is smaller than that of its rotor and operable in
conjunction with a suitable, smaller-sized stator ring-gear.
Fig. 7B is a sectional, partly cut-away, axial view of the PPPEM 114 from Fig.
7A showing the arrangement in axial profile of the series of radially mounted
electromagnets 42. Stator ring-gear 120 is shown oversized by way of example only,
as a stator ring-gear can also have a diameter smaller than the diameter of a rotor gear
with which it meshes as explained in the description of Fig. 7A.
Fig. 8A is an orthographic, cut-away view of the PPPEM 14 from Fig. 7
shown, by way of convenience only, provided with two, alternate types of antibacklash
mechanisms (as detailed in Figs. 8B and 8C) in accordance with another
embodiment of the present invention. PPPEM 1 4 is provided with at least a pair of
an anti-backlash mechanisms 128, 130 which are disposed around the axis of rotor
flange 124 on the exterior faces thereof. One type of anti-backlash mechanism
comprises a pair of adjustable screws 128. Alternatively, another type of anti-backlash
mechanism is a pair of curved compression springs 130. In actual practice only at
least one pair of either one or the other mechanism 128, 130 would be used to control
or eliminate planetary mesh backlash.
Fig. 8B is an axial view of the rotor flanges 124 with rotor gear 122 from Fig.
8A showing the disposition of the first type of anti -backlash mechanism in accordance
with the principles of the present invention. Compression screws 128 are adjustable
within respective curved slots which are oriented parallel to the circumference of
flanges 124 and equidistant from rotor axis 50. Anti-backlash mechanisms are paired
for balance when rotated, for example, clockwise in the direction of the curved arrows
132, when impelled by a PPPEM (not shown).
Fig. 8C is an axial view of the rotor from Fig. 8A showing the disposition of
the second type of anti-backlash mechanism in accordance with the principles of the
present invention. The pair of compression springs 130 are accommodated axially
within their respective, curved recesses of rotor flange 124. The pair of anti-backlash
springs 130— s well as the pair of adjustable screws 128—are balanced on rotor
flanges 124 by being positioned at equal distances and on opposite sides from rotor
axis 50 so as to eliminate planetary mesh backlash when rotor gear 122 is operated.
Fig. 9A is a sectional view of a PPPEM provided with tubular, radial magnetrings
in accordance with still another embodiment of the present invention.
PPPEM 134 is provided with an externally mounted ring stator 38 containing a
series of radially mounted electromagnets 42a/b/c. ..j k l and integral to a stator gear
40, all enclosed within a housing envelope 44.
An internal, eccentrically mounted planetary rotor 136 comprises a rotor gear
140 integral with a magnetic rotor-ring 138 seated on a rotor core 142. Rotor gear 140
meshes with stator gear 40 and rotates about eccentric rotor axis 50 when PPPEM 134
is operated. Tubular, radial magnets 144, which are part of rotor case 142, are
attached to planetary rotor 136 and concentric with rotor axis 50. Note that magnetic
North poles (N) are oriented so as to point radially outward and the South poles (S)
are consequently pointing towards rotor axis 50.
When stator electromagnets 42j, 42k, and 421 are turned on, their North (N)
poles point towards stator axis 52 at the same time that tubular, radial magnets 144 are
oriented such that a North (N) magnetic polarity causes repulsion between the like
magnetic poles to those of stator electromagnets 42j, 42k, and 421. Thus push forces
146 (arrow) are generated which push planetary rotor 136 to pivot upon moving, pivot
contact line 60 and planetary rotor gear 140 meshes with stator ring-gear 40.
Simultaneously, stator electromagnets 42b, 42c, and 42d, when turned on with
their South (S) magnetic poles pointing to the opposite, North (N) magnetic polarity
of tubular, radial magnets 144 cause a magnetic attraction. A magnetic pull force 148
is exerted on planetary rotor gear 140 which is integral to planetary rotor 136.
Consequently planetary rotor 136 is impelled by push-pull magnetic forces 146, 148,
respectively, to rotate in a continuous, rolling motion which advances planetary rotor
136 from moving, pivot contact line 60 to other temporary mesh contact positions
around stator gear 40.
Fig. 9B is a detailed sectional view of planetary rotor 136 from Fig. 9A
showing the tubular, radial magnets 144 integral to rotor case 142 and the orientation
of the S and N magnetic poles as explained heretofore in respect to Fig. 9A. Tubular,
radial magnets 144 are built into rotor case 142 as a one-piece unit with given
magnetic poles configured around the outer edge of rotor case 142 with all like
magnetic poles inwardly or outwardly oriented, as needed for various applications.
Fig. 9C is a sectional view of the planetary push-pull motor from Figs. 9A B
showing an exemplary manner of operation of magnetic forces to drive the rotation of
an internally mounted planetary rotor in accordance with the principles of the present
invention.
A series of stator electromagnets 42 a-1, in a preferred embodiment of the
present invention, can be activated in any sequence. For example, stator
electromagnets 42b, 42c, and 42d are shown activated in Fig. 9C with their North
poles (N) directed radially outwardly. Simultaneously, stator electromagnets 42j, 42k,
and 421 are activated with their North poles (N) directed radially inward. This
combination of magnetic forces (indicated by magnetic poles marked N or S) impels
rotor 6 to pivot clockwise about moving, contact pivot line 60 where rotor gear 140
and stator gear 40, temporarily come into balanced mesh contact with one another
until actuation of the aforementioned electromagnets 42.
Similarly, a counterclockwise rotation of rotor 136 can be made utilizing these
same six electromagnets, where 42j is off, 42k, 421 are live with their North poles (N)
directed radially outwardly, while simultaneously 42b, 42c, and 42d are activated with
their North poles (N) directed radially and inward.
Other combinations and sequences of activation of the stator electromagnets
42, wherein even numbers of them can be made live simultaneously, will provide
different angles between activated magnetic poles to pivot planetary rotor 136 one
way or another about any desired pivot contact line, such as moving, contact pivot
line 60, as may be required in various applications of PPPEM 134.
Fig. 9D is a sectional view of the PPPEM from Figs. 9A/B/C showing radial
magnetic forces in operation in accordance with the principles of the invention.
Unlike conventional, prior art electric motors where the rotational vector is
approaching the tangential rotating force in relation to a rotor, and the rotor axis is
coaxial with the stator axis, in the PPPEM 134 illustrated in Fig. 9D of the present
invention, the magnetic pull forces 146 and push forces 148 (series of arrows)
between planetary rotor 136 and stator 38 are radial and produce a push-pull effect
where the axis of rotation is not the rotor axis 50 (shown on end as a point), but the
tangent to the line of contact, i.e., the moving, mesh contact pivot line 60 (shown as a
point) between stator gear 40 and rotor gear 140.
Fig. 10 is a sectional view of a PPPEM, by way of example, provided with a
mechanism to detect and measure rotor speed and direction of rotation, cam shaft-tostator
relative location, and rotor-to-stator orientation to a pivot contact line in a
specified location, in accordance with the principles of the present invention.
PPPEM 150 comprises an external ring stator 38 and stator gear 40 within a
stator casing 44, and an eccentric planetary rotor 46 integral to rotor gear 48. A cam
shaft indicator 156 (represented by a large, downward pointing arrow) is rotationally
attached to the cam shaft 152 coaxial with stator axis 52 and set so as to initially point
in the direction of mesh contact point 60 (by way of example) between stator 8 and
rotor 46. Cam shaft 152 can rotate, for example, about 24 revolutions during the same
period of time that planetary rotor 46 rotates only one revolution, therefore it is
possible to accurately detect and measure rotor speed and/or direction of rotor rotation
and/or rotor relative position to the stator 38 via cam shaft 152 which rotates at a
speed multiple to that of planetary rotor 46.
A single Hall Effect sensor 34 is disposed at the stator 38 for measuring the
magnetic flux in the system when PPPEM 150 is operated. At least three small
magnets 154a-c are positioned on the cam shaft indicator 156 in close proximity to
Hall sensor 34. When magnets 154a and 154c are asymmetrically oriented to magnet
154b, it is possible to measure cam shaft speed and direction of rotation, and cam
shaft-to-stator absolute orientation and at a high resolution by use of an optical
encoder, resolver, photo diode sensor, or any other method as is known to those
skilled in the art.
Alternatively, a digital converter (not shown) can be provided to convert the
analog data provided by indicator 156 into a convenient digital form for display on a
standard monitor screen as is known to those skilled in the art.
Fig. 11 is an orthographic, partial cut-away view of another embodiment of the
present invention. PPPEM 160 comprises an external, gearless, friction stator 164 and
an internally mounted, eccentric, gearless, friction planetary rotor 162.
In this friction mesh concept, the at least a pair of friction rings 158 can be in a
diameter slightly smaller than the stator internal diameter; the rotor-to-stator
eccentricity, therefore, will be very small and the rotor-to-stator air gap will also be
very small. The magnetic interaction forces will be stronger and the cam shaft-to-rotor
ratio will consequently be higher.
Rotor 162 rotates eccentrically about axis 50 when PPPEM 160 is operated,
being offset from stator axis 52 by a gap 54. Rotor 162 is provided with at least a pair
of friction rings 158. This construction increases the rotor-to-stator ratio up to about
1:100.
Stator 164 is provided with a series of electromagnets 42 arranged radially
about the stator axis 52 which is coaxial with an output shaft (not shown). Stator 164
is housed in stator casing 44 which also conveniently serves as housing for PPPEM
160.
Fig. 12A shows an orthographic partial cut-away view of a friction-type
PPPEM in yet another embodiment of the present invention. PPPEM 166 comprises
an external friction stator 164, which is provided with a series of electromagnets 42
arranged radially about the stator axis (not shown) and which defines the centerline of
PPPEM 166. Stator 164 is housed in an envelope 44 which also serves as a convenient
housing for PPPEM 166. Planetary friction rotor 162 is provided with at least a pair of
friction rings 158 as in PPPEM 160 (see Fig. 11).
An eccentric cam shaft 170 (see details in Fig. 3A) and a tubular bearings
element 1 6 are provided to maintain the eccentricity gap 54 (see Fig. 1) between
the axes 50, 52 (see Fig. 11) of planetary friction rotor 162 and stator 164,
respectively, and also to reduce friction during the rotation of eccentric cam shaft 170
and planetary friction rotor 162, which are the principal rotating elements when
PPPEM 166 is operated. Each of these rotating elements rotates at different speeds,
but they are all dynamically balanced.
The eccentric cam shaft 170 has a double-D section profile that slidingly f t
with the internal double-D openings at the bearing filler seats 178. This particular
mechanism keeps the cam shaft 170 and bearing seat at the same orientation but
permits a radial movement of rotor 2 toward stator 164 to produce the friction
contact needed for the planetary mesh torque transfer.
PPPEM 1 6 is also provided with at least a pair of axially mounted, radial
compression springs 1 2 preloaded for ensuring positive rotor-to-stator engagement at
a predetermined load for the desired friction needed for a specific torque transfer. The
at least a pair of compression springs 172 are each fitted with matching spring shoe
elements 174 housed inside eccentric cam shaft 170 for applying pressure on the
planetary friction rotor 162 at the moving mesh contact point 60 (see Fig. 12B)
between rotor 162 and stator 164 which varies with the rotation of planetary friction
rotor 162. Enclosing compression springs 172 and spring shoe elements 174 are
bearing element seats 178 which maintain compression springs 172 oriented radially
during rotation of planetary friction rotor 162.
Fig. 12B is an orthographic, partially cut-away, sectional view of the motor
from Fig. 12A showing details of the rotor construction. PPPEM 166 is shown
provided with two rotating elements: eccentric cam shaft 170 and planetary friction
rotor 162 with at least a pair of friction rings 158. Cam shaft 170 is
eccentrically mounted so that planetary friction rotor 162 is offset from stator axis 52
(see Fig. 11) of friction stator 164 at a specified gap 54 (see Fig. 11). Cam shaft 170
also maintains the centerline of rotation which is defined as rotor axis 50 (see Fig. 11)
at a specified offset from stator axis 52 (see Fig. 11). The two rotating elements 170,
162 are free to rotate independently of one another and at different speeds.
Tubular, bearings element 176 is provided to reduce rotational friction
between them. A pair of compression springs 172, as in Fig. 12A, is seen in profile
here housed within eccentric cam shaft 170. Note the moving, pivot contact line 60
between planetary friction rotor 162 and stator 164 which are in contact only through
friction rings 158. Other elements are as described heretofore in relation to Fig. 12A.
Fig. 13A is a sectional, cut-away view and an enlarged detail view of another
embodiment of a PPPEM provided with gears, radial springs and a tubular bearings
element to promote zero backlash.
PPPEM 180 comprises an externally mounted ring stator 38 integral to an
internal stator gear 40 and is provided with a series of electromagnets 42 enclosed in a
stator envelope 44. Planetary gear motor 0 further comprises an internally mounted,
soft steel planetary rotor 190 integral to planetary rotor gear 48 and a tubular, bearings
element 176 centrally mounted within planetary rotor 190. Moving, mesh, pivot line
60 (shown as a point in this axial view) represents the closest proximity between
planetary rotor gear 48 and stator gear 40 by way of illustrating the eccentric
relationship between them.
Tubular, bearings element 176 is shown in the detailed enlargement as
containing bearings 186 confined between inner and outer walls, 182 and 184,
respectively. Eccentric cam shaft 170 is provided with at least one pair of
compression springs 172 each mounted on an inverted, T-shaped, spring shoe element
174 which is kept in place by a retainer filler seat 178.
A pair of spring shoe elements 174 is oriented in such a way within the
confines of cam shaft 170 and bearings filler seat 1 8 so as to exert a radial pushing
force towards the inner bearings housing 182 by force of a pair of compression
springs 172. A small clearance gap 192 is provided for expansion of compression
springs 172 which applies a positive force at any mesh pivot line along the path of
planetary motion taken by planetary rotor 190, such as, for example, mesh pivot line
60 on planetary rotor gear 48.
The downward, radial expansion movement of the pair of compression springs
72 and resultant movement of spring shoe elements 174 promote zero backlash when
planetary rotor gear 48, for example, fully meshes with stator ring-gear 40 at a typical
mesh pivot line 60 upon operation of PPPEM 180.
Fig. 13B is a simplified schematic view of the action of one of the pair of
typical radial compression springs 172 (see Fig. 1 A and detailed view). As indicated
by arrow 188, compression springs 172 are free to move, together with planetary rotor
190, towards stator gear 40 to eliminate possible backlash caused by gear meshing
and to adjust the eccentricity between gears 40, 48 when they engage and mesh.
Fig. 14 is a sectional view of a PPPEM, in another embodiment of the present
invention, which utilizes a planetary rotor having flexible couplings to align the rotor
output shaft coaxial with the axis of the stator for direct power transfer.
PPPEM 200 comprises an externally mounted, gearless, stator 164 provided
with a series of electromagnets 42 mounted on coil cores 196. The series of
electromagnets 42 are arranged radially about stator axis 52 which defines the
center line of PPPEM 200.
Internally mounted, gearless planetary rotor 62 is provided with at least a pair
of elastomeric friction rings 158 to establish a constant, rolling force, temporarily
shown as pivot contact line 62 between gearless, planetary rotor 162 and gearless
stator 164. The eccentric rotor axis 50 passes through an offset cam shaft 168, but is
aligned to meet with and connect to an angled coupling rod 202 through a rotor flange
204 and then a first flexible coupling 206a.
The connection between coupling rod 202 and output shaft 74 is through a
second flexible coupling 206b which restores the axis of PPPEM 200 from the
eccentric rotor axis 50 through cam shaft 169 at the proximal end of PPPEM 200
which is shown aligned with stator axis 52 and output shaft 74. Output shaft 74,
whose centerline is thus coaxial with stator axis 52, receives a direct power transfer
along the common axis between them.
The entire mechanism of flexible couplings 206a/b and connecting rod 202 is
advantageously housed within a tubular bearings element 176 disposed coaxially
within planetary, gearless rotor 162 to reduce friction between moving parts. Flexible
couplings 206a/b are of any kind as is known to those skilled in the art.
Fig. 15A is a detailed, orthographic view of a holder-encased electromagnet
with an integral, E-shaped profile core constructed in accordance with another
embodiment of the present invention.
Single electromagnet 208 comprises windings 214 wound on a central arm
2 of an E-shaped profile case 210.
It should be noted that an electromagnetic core in general may be configured
with a C-shaped, U-shaped, or E-shaped profile, as is commonly known to those
skilled in the art, to accommodate different numbers of coil windings to produce
greater or lesser torque power from magnetic flux as may be required in different
applications. This is true also for various embodiments of the PPPEM of the present
invention.
Fig. 15B is a sectional view of a PPPEM incorporating a series of encased
electromagnets from Fig. 5A, radially disposed within an externally mounted stator.
PPPEM 220, which may be of either the gear type (see Fig. 2) or friction type
(see Fig. 11), is constructed in accordance with the principles of the present invention
and incorporates a series of electromagnet units 208 as shown in detail in Fig. 15A.
A series of encased electromagnets, such as electromagnet 208, optimizes the volume
of ring stator 216 to accommodate more electromagnet windings 14 by encasing
them in E-shaped profile, soft metal cases 210. This advantageously concentrates
magnetic flux from both magnetic poles towards one active face of an electromagnet,
such as central arm 212, in closest proximity to planetary rotor 218 when PPPEM 220
is activated. Planetary rotor 218 is shown in an axial sectional view to illustrate the
eccentric relationship between rotor axis 50 and stator axis 52.
Fig. 15C is an orthographic view showing the details of the ring stator 216
with a series of encased, E-shaped profile electromagnets 208 from the PPPEM 220 of
Fig. 15B.
Ring stator 216 from Fig. 15B is shown with a series of holder-encased
electromagnets 208 arranged within ring stator 216 at an angle to the centerline of
planetary rotor 218 (see 15B), but coaxial with and defined by rotor axis 50 (see Fig.
15B). The holder-encased electromagnets 208 are arranged at an angle within ring
stator 216 primarily to reduce the cogging effect in a typical PPPEM of the present
invention when planetary gears are used.
Fig. 16 is a sectional view of another embodiment of the present invention
comprising a PPPEM with an internally mounted, planetary rotor.
PPPEM 222 comprises an externally mounted, ring stator 164, shown
disposed within a housing envelope 44; a series of electromagnets 42 arranged around
ring stator 164; and an internally disposed, planetary rotor 224. Planetary rotor 224 is
rotatably fixed on a cam shaft (not shown) coaxial with rotor axis 50. Ring stator axis
52 is offset from this by a minimum offset gap 54 which allows for no direct rotor-tostator
contact at all, as reflected by the minimum clearance gap 226. The efficiency in
the output of PPPEM 222, when operated in accordance with the principles of the
present invention, is greatly increased.
Planetary rotor 224, in a preferred embodiment of the present invention, is
made from ferromagnetic material, such as soft iron, nickel, cobalt, ferrite, and the
like, having a high magnetic permeability for use within a stator magnetic field.
Fig. 17A is an orthographic view of a prior art motor connected to a lead
screw shaft through a prior art gear box. A prior art electric motor 20 is connected to a
gear box 230 and connected through a flange 234 to drive a lead screw shaft 232 that
provides output power as is known to those skilled in the art. Lead screw shaft 232
rotates as indicated by rotational arrow 2 8. A movable nut 236 travels laterally
(shown by arrow 228) along the length of lead screw shaft 232 in either direction, in
accordance with the direction of rotation, clockwise or counterclockwise, of lead
screw shaft 232.
Fig. 17B is an orthographic, partially cut-away drawing of a PPPEM
constructed with a gearless planetary rotor for direct operation of a lead screw shaft,
in accordance with the principles of the present invention.
PPPEM 240 comprises an externally mounted stator 164 having a series of
electromagnets 42 (see Fig. 1 ) and having an internally mounted planetary rotor 162,
with at least one elastomeric friction ring 158. Planetary rotor 162 provides for direct,
control of a fixedly attached, rotatable lead screw shaft 232 having a laterally movable
nut 232 and rotatably attached at a distal end to a ball joint 242.
Planetary rotor 162 is gearless and integrally connected to lead screw shaft
232 such that rotation of planetary rotor 162 causes the direct rotation (rotation arrow
238) of lead screw shaft 232 without the need for connection to gears through a gear
box 230 (Fig. 17A) as used in the prior art. The distal end of lead screw shaft 232
comprises a ball joint 242 to anchor lead screw shaft 232 while continuing to allow
rotational movement so that movable nut 236 is free to move in either axial direction
(arrow 228) along the fixed length of lead screw shaft 232 when motor 240 is
operated. The direction of rotation of lead screw shaft 232, and hence the direction of
lateral movement of movable nut 236, is directly dependent upon the clockwise or
counterclockwise rotation (arrow 238) of rotor 162.
The present invention shown in Figs. 17A/B is an improvement over the prior
art electric motor and useful for devices with movable elements requiring b i
directional back and forth movement, such as the zoom lenses in cameras, mobile
portions of advertising displays, and the like. These movable elements are connected
to movable nut 236 and thus move with it when PPPEM 240 is operated.
Fig. ISA shows a general schematic view of a typical prior art, U-shaped
holding electromagnet whose two arms on a ferromagnetic core are wound with two
electrical coils and shows the flow and polarity of a resultant magnetic flux through
the core and an associated armature when the electrical coils are activated.
The prior art electromagnet 250 comprises a U-shaped profile, ferromagnetic
core 246 which has electrical coils 244a and 244b wound, respectively, on polar arms
252a and 252b (shown as N=North; S=South, respectively) so that their polarities are
oppositely charged. An armature 248 is provided to allow the magnetic field to flow
in a closed circuit in the direction as indicated by the arrow 254.
Fig. 18B shows a general schematic view of a typical prior art, E-shaped
holding electromagnet whose three arms on a ferromagnetic core are wound with
three electrical coils and showing the flow and polarity of a resultant magnetic flux
through the core and an associated armature when the electrical coils are activated.
Prior art electromagnet 260 comprises an E-shaped profile, ferromagnetic core
256 which has electrical coils 244a and 244b alternatively wound, respectively, on the
three adjacent polar arms 252b, 252a and 252b (shown as S=South, N=North;
S=South, respectively) so that their polarities alternate between S-N-S (or optionally,
N-S-N). An armature 248 is provided to allow the magnetic field to flow in a closed
circuit, but unlike the flow in the U-shaped profile electromagnet of Fig. , the
magnetic flow in the E-shaped profile electromagnet 260 follows the dual paths as
indicated by arrow 254.
Figs. 19A and 19B illustrate a typical first and second step operation,
respectively, of a PPPEM constructed in accordance with the principles of the present
invention. PPPEM 262 is provided with an externally mounted ring stator 264 whose
stator axis 52 defines and is coaxial with the centerline for the output shaft (not
shown) of PPPEM 262. An internally mounted, planetary rotor 266 comprises a
tubular, soft iron, radial ring 278 having an integral rotor core 272. Rotor axis 50 is
eccentric to the centerline axis of ring stator 264.
Ring stator 264 is provided with a series of electromagnets 268 (such as
268c/d in Fig. 19A and also, by way of example, 268e in Fig. 19B) with U-shaped
profile cores 246 (see Fig. 18A), which are configured with a North (N) magnetic pole
on one core arm 252c and a South (S) magnetic pole on the other core arm 252d. All
the electromagnets 268 in ring stator 264 are disposed within stator 280. PPPEM 262
is enclosed in a motor housing 280 which also serves as a casing to ring stator 264.
Referring now to Fig. 1 A in particular, ring stator 264 comprises a series of
2 electromagnets, by way of example, electromagnet 268c whose magnetic polarity
is shown as N (North) on one arm 252c of a U-shaped profile core 246 (see Fig. 18A)
and on the second arm 252d, the magnetic polarity is shown as S (South) such that
electromagnet 268c and adjacent electromagnet 268d are serially connected although
their coi! windings 270c and 270d, respectively, create opposite magnetic polarity on
each of the arms of the U-shaped profile core 246.
In a first step of operation, electromagnets 268c and 268d, although of
opposite magnetic polarity, work in tandem (on the same U-shaped profile core 246 -
see Fig. 8A) to impel planetary rotor 266 to rotate in pivotal increments of 60
degrees in relation to the rotational movement of a cam shaft (not shown, but coaxial
with eccentric rotor axis 50) from a first, moving pivot line 60a in a direction of
rotation dependent on the pull forces when PPPEM 262 is operated.
Referring now to Fig. 19B, electromagnet 268d whose magnetic polarity is
now shown as S (South) and electromagnet 268e whose magnetic polarity is now
shown as N (North) have attracted tubular, soft iron ring 278 from a first, moving
pivot line 60a (Fig. 19A) to a sequential, second pivot line 60b at about 30 degrees
from the first, moving pivot line 60a.
Electromagnet coil 270d is serially connected through its windings to coil
270e which has a North (N) magnetic polarity and creates a new impetus for planetary
rotor 266 to continue rolling. There are always at least two adjacent electromagnets
268 which operate together in series connection to pull planetary rotor 266 by creating
opposite magnetic polarity on each of the arms 252d/e of the U-shaped profile core
246 (see Fig. 18A).
Figs. 20A and 20B illustrate a typical two-step operation of a PPPEM having a
series of E-shaped profile electromagnet cores and constructed in accordance with the
principles of the present invention. In PPPEM 282 of Figs. 20A/B, a group of coils
286c/d/e, such as in electromagnets 284c/d/e are activated simultaneously, where the
mean attracting vector of the three coils 286c/d/e always remains perpendicular to the
rotor radius and oriented toward the temporary, rolling-motion pivot contact line 60a
in a kind of balance.
Referring now in particular to Fig. 20A, PPPEM 282 comprises an externally
mounted, ring stator 264, with a series of electromagnets, such as 284c/d/e provided
with E-shaped profile cores 256 (see Fig. 18B) arranged around the central axis 52 of
ring stator 264; and an internally disposed, planetary rotor 266 having a magnet core
272 integrally constructed with six arms 274 disposed equidistant from one another in
a radial arrangement. The PPPEM 282 is housed in motor housing 280 while
planetary rotor 266 is provided with a tubular, soft iron, radial ring 278 integral to
planetary rotor 266.
PPPEM 282 is provided with coil windings 286 c/d/e which are serially
connected so that the magnetic polarity of the middle core arm (marked S=South
pole), by way of example, is opposite to that of the two adjacent end core arms
(marked N=North). The same construction principle that applies to electromagnets
284c/d/e in ring stator 264 are also applicable to the other electromagnets 284 in
groups of three.
In a preferred embodiment of the present invention, ring stator 264 is provided
with electromagnets 284, but any number of electromagnets may be used having
an E-shaped profile core 256 (see Fig. 18B). Contact pivot ine 60a is shown disposed
at a six o'clock position in relation to the axial sectional view of PPPEM 282, and
therefore a first step in the operation of PPPEM 282 is the activation of
electromagnets 284c/d/e to pivotally rotate planetary rotor 266 utilizing the magnetic
force of attraction on planetary, rotor ring 278, which is advantageously made from
soft iron.
The primary difference between the embodiments of the present invention
shown in Figs. 19A/B and Figs. 20A B is the use of a U-shaped profile core 246 (see
Fig. 18A) for the electromagnets 268 in the former drawings, as opposed to the use of
an E-shaped profile core 256 (see Fig. 18B) for the electromagnets in Figs. 20A/B.
Other features are primarily the same between the drawings, but there are some
differences in operation as explained hereinafter due to the nature of the profiles of
the electromagnet cores 246, 256 used in each embodiment of the present invention.
In the case where mesh gears are used in PPPEM 282, movement of planetary
rotor 266 results in a temporary mesh on the pivot contact line (such as 60a) between
a stator gear and a rotor gear (not shown). But PPPEM 282 may also be gearless and
operate with a friction type planetary rotor 162 provided with friction rings 158 (see
Fig. 11).
Referring to Fig. 20B, a second pivot line 276b is now established in the five
o'clock position between stator 264 and planetary rotor 266. Electromagnet 284c will
be deactivated and electromagnet 284f at the one o'clock position will be activated at
the same time to continue the pivotal rolling motion of planetary rotor 266. Note that
in this second step, electromagnets 284d/e/f are now activated. Further movement will
result with continuous activation and deactivation of relevant electromagnets in a
sequential, running series.
Figs. 2 A and 2IB illustrate the front face 288a and back face 288b,
respectively, of a prior art ring-magnet 290 showing the opposite, axially oriented
magnetic polarities (N and S) of each face. Ring magnet 290 may be a ring or a
cylinder magnet, but they both have axially oriented magnetization and are quite
commonly used since they are much cheaper to produce than radial magnets. In
particular applications, the magnetic flux lines can be selected that are radially
oriented and this face ring magnet can them be used in constructing an improved
PPPEM combining conventional ring magnets with the push-pull advantages in
accordance with the principles of the present invention.
Fig. 22 shows a cross-sectional orthographic view of a PPPEM comprising an
externally mounted, ring stator with a series of electromagnets with windings on
axially oriented U-shaped profile cores and constructed in accordance with another
embodiment of the present invention.
PPPEM 300 comprises an externally mounted stator 294 with a series of
electromagnets 250 with windings 270a/b on U-shaped profile cores 246 and the
whole enclosed in a stator case 44 which conveniently also serves as a motor housing
for PPPEM 300. An internally disposed planetary rotor 296 is formed from a
conventional, prior art ring-magnet 290 which is axially oriented and encapped on
each face 288a/b (see Figs. A/B) with a magnetic flux guide 292a .
Stator electromagnets 250a/b are operated in close proximity to the magnetic
poles of magnetic flux guides 292a/b and rotor ring-magnet 290 when the opposite
magnetic polarity is given to electromagnet 250a as that of the poles of magnetic flux
guides 292a/b and rotor ring-magnet 290. This produces an attraction force that pulls
rotor ring-magnet 290 in a downward direction.
Meanwhile, an electromagnet 250b disposed at an upper portion of PPPEM
300, shown in Fig. 22 above rotor ring-magnet 290, is given the same magnetic
polarity as that of the poles of magnetic flux guides 292b and rotor ring-magnet 290.
The sum of both repulsion and attraction magnetic forces acting downward impels a
series of pivotal movements which results in production of a torque in an output shaft
(not shown) which can be put to use in many applications within the power range of
PPPEM 300.
Fig. 23 is an orthographic, partially sectional view of still another embodiment
of the present invention. Fig. 23 shows a PPPEM 302 with an externally mounted
stator 318 integral to a stator ring-gear 314 which meshes with planetary rotor gear
312 when PPPEM 302 is operated. Electromagnets 250 with U-shaped profile cores
246 are arranged in a series in stator 318 and enclosed in a case 44.
An internally disposed planetary rotor 316 is provided with a rotor gear 312
and attached to an Oldham coupling device 304 through an Oldham rotor plate 306,
mid-plate 308, and finally to an Oldham output shaft 310. The Oldham output shaft
3 10 is coaxial with the stator axis 52 (see Fig. 2) which defines the centerline of
PPPEM 302 so that the offset between rotor axis 320 is restored coaxially with the
stator axis 52 at output shaft 310. Planetary rotor 316 comprises an axial ring-magnet
290 provided with magnetic flux guides 292a/b. Other features displayed in Fig. 23
are as those described heretofore in regard to Fig. 22.
Fig. 24 is an orthographic, sectional view of a gearless, PPPEM in yet another
embodiment of the present invention. PPPEM 322 is provided with an externally
mounted stator 164 having a series of electromagnets 42, an internally disposed,
gearless, planetary rotor 162, and provided with an anti-backlash mechanism (see
Figs. 3A/B), but also comprising prior art, axial ring-magnets 290 encapped on two
faces with a pair of magnetic flux guides 292a b. Other features and elements of
W
PPPEM 322 are similar to those shown in the embodiment of the present invention
shown in Fig. 1.
The principle feature of the embodiment shown in Fig. 24 is the improved
anti-backlash mechanism which operates to pull planetary rotor 162 in a downward
direction by force of attraction between planetary rotor 162 and ring stator 164, by
using an axial ring-magnet 290 (with or without the magnetic flux guides 292a/b
which are rigidly connected to and are a part of planetary rotor 162) which will
provide attraction between planetary rotor 162 which is made of soft iron material and
ring stator 164.
Fig. 25 is an orthographic, partially sectional view of another embodiment of
the present invention. Fig. 25 shows a PPPEM 324 constructed with multiple,
relatively thin, U-shaped profile electromagnet core arms 332a (N pole) and 332b (S
pole) axially arranged on a wide, inner backing surface 330 of an external ring stator
326 to accommodate multiple N and S magnetic poles 332a b to magnetically rotate
an internally disposed, soft metal, rotor ring 328. Rotor ring 328 may be made of
other ferromagnetic materials as are known to those skilled in the art, but herein the
preferred material is soft iron.
Fig. 26 is an orthographic, sectional view of a preferred embodiment of the
present invention. Fig. 26 shows a PPPEM 334 comprising an externally mounted
stator 336 with a stator gear 338 and stator electromagnets 340 arranged radially in a
series about a central stator axis 52 (see Fig. 2) coaxial with the axis of PPPEM 334
output shaft 352. An offset, rotor cam shaft 342 is provided with an anti-backlash
mechanism 344 which may be any type known to those skilled in the art, but
preferably a pair of compression springs 172 as shown in detail in Fig. 13A.
Internal planetary rotor 346 is equipped with a first rotor ring-gear 312 that is
in mesh contact with stator gear 338 at moving, contact pivot line 60. A second rotor
ring-gear 348 is in mesh with output ring-gear 350 for both converting planetary rotor
eccentric rotation into a concentric output rotation for output shaft 352, and as an
output reduction stage of, for example, about 1:20. In this way, therefore, cam shaft
342 is the perfect place to implement a shaft encoder, resolver, and/or a brake.
Ring 288 is attached to the cam shaft 342 and acts as an interrupter to the
photo interrupter sensors 353 in order to detect the relative orientation of pivot contact
line 60 to the electromagnets 340. A secondary set of planetary gears 348 and 350 are
either for speed reduction moment multiplication or for bringing the output shaft 3 2
to be concentric with that of the stator centerline, defined by ring stator axis 52 (see
Fig. 2)
A pair of compression springs 172 (see detail view in Fig. A) of antibacklash
mechanism 344 are loaded for rotor ring-gears 312 and 348 to engage with
stator ring-gear 338 and output gear 350 to produce the two-stage, anti-backlash
mechanism.
It should be noted that PPPEM 3 4 has three main rotating elements.
1) the planetary rotor 346 with its integral gears 312, 348 which rotate in a planetary
mode upon stator gear 338;
2) the eccentric, rotor cam shaft 342, which rotates at a relatively higher speed than
that of planetary rotor 346 (for example, the eccentric, rotor cam shaft 342 will rotate
5 or 30 times faster than the speed of planetary rotor 346); and
3) the output shaft 352 with its integrated, internal ring-gear 350 which rotates at a
relatively lower speed than that of planetary rotor 346.
Planetary rotor 346 is the element that is impelled by electromagnets 340 and
wil transfer a given torque in a certain direction and at a given speed to the second
output planetary mesh gears 348, 350, of output shaft 352. The eccentric cam shaft
342 is intended to keep planetary rotor 346 at a given offset and at a parallel
orientation in relation to ring stator axis 52. Since the eccentric rotor cam shaft 342
rotates at a speed multiple to that of planetary rotor 346, it is the optimal element for
placing any kind of sensor, either for indicating position or velocity, or for
accommodating a holding brake, which is a very low torque brake (for example, the
brake holding torque will be times less than the maximum rotor torque).
An optical absolute encoder constructed of washer plate 288 and about eight
photo-interrupter sensors 353, are used to identify rotor-to-stator relative position, and
in particular the relative position of the rotor pivot contact line 60 in relation to the
magnetic poles of the stator electromagnets 340.
Washer plate 288 is rotatably fixed with eccentric rotor cam shaft 342 where
the photo interrupters 353 are fixedly connected to a stator case 44 including motor
rear cover 354.
As is known by those skilled in the art, the relative location of a given pivot
contact line to the electromagnets is essential for an optimal activation of the
electromagnets for impelling planetary rotor 346 at maximum moment and or
maximum efficiency (for example, in a clockwise or counter-clockwise direction).
It will therefore be appreciated that the device described herein and illustrated
in the accompanying drawings is set forth merely for purposes of example and that
many other variations, modifications, and applications of the present invention may
be made. Having described the present invention with regard to certain specific
embodiments thereof, it is to be understood that the description is not meant as a
limitation, since further modifications may now become apparent to those skilled in
the art, and it is intended to cover such modifications as fall within the scope of the
description, drawings, and appended claims.
I claim;
. A planetary push-pull electric motor (hereinafter: "PPPEM") comprising:
a ring stator fixedly mounted on a central axis of said PPPEM, wherein
said central axis defines a centerline of said ring stator;
a planetary rotor arranged to be magnetically movable, rotatably mounted
on an eccentric rotor axis in respect to said ring stator centerline;
a series of electromagnets radially mounted about said ring stator
centerline for generating radial magnetic force upon the magnetic fields of said
planetary rotor when said series of electromagnets is activated,
a means for transferring rotation of said eccentric planetary rotor axis to
directly power an output shaft of said PPPEM .
wherein when said series of electromagnets is activated, radial push-pull
magnetic forces are generated, magnetically impelling said planetary rotor in
proximal radial contact with at least one electromagnet in said series such that said
planetary rotor pivots from one of said proximal tangential contact to an adjacent one
in sequence, effecting a continuous rolling motion of said planetary rotor about said
eccentric rotor axis and creating a rotary moment, such motion being translated into
rotational motion which, when applied to said output shaft of said PPPEM utilizing
said rotation transferring means, provides a source of power output from said PPPEM.
2 . The PPPEM of claim 1, wherein said ring stator and said planetary rotor are
gearless.
3. The PPPEM of claim 1, wherein said ring stator comprises an internally toothed
stator ring-gear and said planetary rotor comprises a toothed rotor gear that mesh with
each other and act as a planetary gear set.
4 . The PPPEM of claim 2, wherein said gearless planetary rotor is radially
loaded upon said ring stator and provides a zero backlash friction drive mechanism.
5. The PPPEM of claim 2, wherein said planetary rotor rotates in an eccentric
movement about an inner surface of said ring stator in tangential friction contact
therewith via at least one friction ring provided on the outside surface of said
planetary rotor and disposed so as to be coaxial with said rotor axis.
6. The PPPEM of claim 2, wherein said PPPEM is a planetary friction motor
comprising an internally mounted, friction, planetary rotor in contact with an
externally mounted, gearless stator, said planetary rotor being directly connected to a
lead screw at a proximal end, and to a ball joint at a distal end allowing for free
rotation of said planetary rotor and attached lead screw, said lead screw being
provided with a movable nut mounted thereon such that said movable nut is impelled
to travel along the length of said lead screw in either direction.
7. The PPPEM of claim 1, wherein said rotor axis is radially loaded upon said
stator such that the pull forces pull said planetary rotor toward said stator in order to
ensure zero backlash when said planetary rotor and said stator are equipped with
toothed gear.
8. The PPPEM of claim 1, wherein said rotor gear is mounted on a flange
provided with an anti-backlash mechanism.
9. The PPPEM of claim 8, wherein said anti-backlash mechanism comprises a
balanced pair of compression springs.
10. The PPPEM of claim 8, wherein said anti-backlash mechanism comprises a
balanced pair of screws and associated locking nuts.
1. The PPPEM of claim 8, wherein said anti-backlash mechanism comprises a
balanced pair of radial magnet-rings which produces a constant attraction force
between said planetary rotor and said stator.
12. The PPPEM of claim 1, wherein said push-pull magnetic forces generated by
said series of radially oriented electromagnets interacting with a radial rotor magnet
produce vectors which are radially directed inwardly toward and outwardly about said
rotor axis.
13. The PPPEM of claim 1, wherein the axis of said planetary rotor is parallel
oriented with the axis of said stator, but has a radial degree of freedom.
14. The PPPEM of claim 1, wherein the axis of said planetary rotor is radially
loaded toward said stator in order to keep said planetary rotor idle when said PPPEM
s not operating.
15. The PPPEM of claim 1, wherein the axis of said planetary rotor is radially
loaded upon said stator in order to create a given friction between said planetary rotor
and said stator.
16. The PPPEM of claim 1, wherein said radial load comprises a tubular, bearings
element.
17. The PPPEM of claim 16, wherein said tubular, bearings element comprises:
a compression spring;
a spring shoe element driven by said compression spring;
an eccentric rotor cam shaft for housing said compression spring and
spring shoe element; and
bearings rotatably confined within an inner and outer tube of said
tubular, bearings element, and accommodating said cam shaft, said compression
spring, and said spring shoe element within a hollow core of said tubular, bearings
element,
wherein when said compression spring compresses said spring shoe element
mounted within said cam shaft, radial force is applied against said planetary rotor gear
for positive, gear-tooth meshing with said stator ring-gear without backlash.
18. The PPPEM of claim 16, wherein said tubular, bearings element comprises:
an eccentric rotor cam shaft;
a pair of flexible couplings connected to a respective pair of flanges; and
a connecting rod mounted between said pair of flexible couplings through
respective flanges thereof,
wherein when said planetary rotor rotates, said rotor axis is shifted so as to be
coaxial with said stator axis, said PPPEM provides direct power output through said
output shaft.
1 . The PPPEM of claim 1, wherein the pull forces pull said planetary rotor
toward said stator and produce a given friction force between them.
20. The PPPEM of claim 1, wherein only a segmental portion thereof comprises
said PPPEM.
21. The PPPEM of claim 20, wherein said segmental portion has at least two
segments of said radially mounted electromagnets on said stator while virtually
maintaining the planetary gear ratio as in the whole of said PPPEM.
22. The PPPEM of claim 1, wherein said PPPEM has a low gear-ratio of about
1:4.
23. The PPPEM of claim 1, wherein said PPPEM has a high gear-ratio of about
1:500.
24. The PPPEM of claim 1, wherein said planetary rotor comprises a primary
planetary gear in mesh contact with said stator gear, and a secondary step-gear
integral with said primary planetary gear in planetary mesh contact with an output
ring-gear integrally connected to an output shaft, such that when said PPPEM is
operated, said secondary step-gear acts as a reducer, and so as to minimize the offset
between said stator axis and said rotor axis to provide a high gear-ratio directly to said
output shaft in alignment with said stator central axis.
25. The PPPEM of claim 24, wherein said secondary step-gear, in planetary mesh
contact with an output ring-gear, integrally accommodates three rotating elements
comprising said planetary rotor, said eccentric cam shaft, and said output shaft, each
rotatable at a different speed.
26. The PPPEM of claim 1, wherein said stator, and said planetary rotor act as a
planetary gear set, but without any contact between them, said stator and said
planetary rotor being kinematically supported by at least one additional pair of
planetary mesh gears to maintain the non-contact condition.
27. The PPPEM of claim 26, wherein said non-contact condition strengthens the
magnetic attraction and/or repulsion between said stator and said planetary rotor when
said stator electromagnets are activated.
28. The PPPEM of claim 26, wherein said at least one additional pair of planetary
mesh gears produces and transfers the output torque of said PPPEM to provide said
power output.
29. The PPPEM of claim 26, wherein said at least one additional pair of planetary
mesh gears is comprised of high-tensile strength materials.
30. The PPPEM of claim 1, wherein said planetary rotor comprises a soft-metal
part.
31. The PPPEM of claim 1, wherein said planetary rotor comprises at least one
permanent magnet.
32. The PPPEM of claim 1, wherein said planetary rotor further comprises a
series of radial tube-magnets, where all similar poles are similarly oriented in one of
an outward direction and n a direction towards said planetary rotor axis.
33. The PPPEM of claim 1, wherein said planetary rotor comprises a one-piece,
homogeneous, radial magnet.
34. The PPPEM of claim 33, wherein said radial magnet is formed as a tube.
35. The PPPEM of claim 1, wherein said planetary rotor is formed as a tubular
ring.
36. The PPPEM of claim 35, wherein said tubular ring comprises an axial magnet
whose magnetic face is directed to be in close proximity to a U-shaped electromagnet.
37. The PPPEM of claim 36, wherein said magnetic face of said axial magnet is
oriented in an outwardly radial direction so the flow of the magnetic flux therefrom
merges radially with the magnetic flux in the core arms of said U-shaped
electromagnet.
38. The PPPEM of claim 36, wherein said axial magnet is provided with a
magnetic elbow guide to direct the flow of the magnetic flux from the face of said
axial magnet in an outwardly radial direction so as to merge radially with the
magnetic flux in the core arms of said U-shaped electromagnet.
39. The PPPEM of claim 1, further comprising an internally mounted, output stepgear.
40. The PPPEM of claim 1, further comprising an externally mounted, output
step-gear.
41. The PPPEM of claim 1, wherein said push-pull forces, when simultaneously
activated, enables accurate control of said planetary rotor position in and about a
steady state condition when aiming, following, and acting as a slave to a target.
42. The PPPEM of claim 1, wherein the planetary mesh gears have a diameter
larger than the diameter of said planetary rotor.
43. The PPPEM of claim 1, wherein the planetary mesh gears have a diameter
smaller than the diameter of said planetary rotor.
44. The PPPEM of claim 1, wherein said planetary rotor and said stator provide
given output torque that varies depending on the diameter of their associated gears.
45. The PPPEM of claim 1, wherein said rotor shaft and an associated cam shaft
comprise two, independent, output shaft elements, each rotatable at a different speed
than the other.
46. The PPPEM of claim 1, wherein said rotor shaft comprises a oad output shaft
which rotates at a relatively low speed.
47. The PPPEM of claim 45, wherein said associated cam shaft rotates at a
relatively high speed.
48. The PPPEM of claim 45, wherein said associated cam shaft accommodates an
add-on device selected from at least one of a low-torque electrical brake, an optical
encoder/resolver, and a combination of the two.
4 The PPPEM of claim 1, wherein both push and pull forces acting at the same
time impel said planetary rotor to rotate in one of a clockwise and a counterclockwise
direction.
50. The PPPEM of claim 1, wherein a serial connection is used to connect
between two oppositely disposed electromagnetic coils when acting at the same time.
51. The PPPEM of claim 1, wherein a parallel connection is used to connect
between two oppositely disposed electromagnetic coils when acting at the same time.
52. The PPPEM of claim 1, wherein at least one magnetic pole at a time of said
series of electromagnets can be activated during motor operation to optimize different,
changing motor missions including: speed change, load change, and an energy saving
mode.
53. The PPPEM of claim , further comprising:
an indicator rotatably connected to said cam shaft, said cam shaft being
coaxial with said stator axis;
a Hall Effect sensor mounted on said stator; and
at least one permanent magnet mounted on said cam shaft in proximity to
said Hall Effect sensor,
wherein, when said PPPEM is operated, said indicator measures relative
position in between said cam shaft and said electromagnets, speed and direction of
rotor rotation, and magnetic flux of said PPPEM.
54. The PPPEM of claim 1, further comprising:
a coupling rod;
a pair of flexible couplings attached at each end of said coupling rod;
a tubular bearings element for housing said coupling rod and said pair of
flexible couplings,
wherein one of said pair of flexible couplings is connected to said rotor
through a flange at said rotor offset axis, and the second of said pair of flexible
couplings is connected to said output shaft along the central axis aligned with the axis
of said stator.
55. The PPPEM of claim 1, wherein said series of electromagnets comprise
holding electromagnets encased in ferromagnetic cases so as to concentrate magnetic
flux from both magnetic poles towards one active face of each of said holding
electromagnets in closest proximity to said planetary rotor when said PPPEM is
activated.
56. The PPPEM of claim 55, wherein said holding electromagnets are connected
in adjacent pairs via the housing formed by said stator where, in one electromagnet of
said pair, the South pole is oriented inwardly and in a second electromagnet of said
pair, the North pole is oriented inwardly in alternating sequence so as to magnetically
rotate said planetary rotor and operate said PPPEM.
57. The PPPEM of claim 55, wherein said holding electromagnets are provided
with soft-iron cores selected from at least one of C-shaped profile cores, U-shaped
profile cores, and E-shaped profile cores.
58. A PPPEM with push-pull poles comprising:
a stator comprising an internally mounted stator integral with a stator gear,
said stator having a series of electromagnets disposed radially around a stator
centerline; and
a planetary rotor comprising an externally mounted, rotor ring integral with
a rotor ring-gear, said rotor-ring and rotor ring-gear being eccentrically aligned in
respect to said stator central axis,
wherein when said series of electromagnets is sequentially activated, said
rotor-ring is impelled by radial, push-pull magnetic forces to roll about a continuous
series of moving tangential contact lines formed by the temporary, sequential, mesh
contact between said rotor ring-gear and said stator gear, such that said planetary rotor
ring advances around the inner circumference of said stator in a continuous rolling
motion providing a source of power output from said PPPEM.