Self-aligning virtual elliptical drive unit

Abstract

To provide a wobble plate drive which is compact and cost-efficient and reduces vibration, heat produced by friction, and binding of gear teeth.SOLUTION: A self-aligning wobble plate drive (110) includes a stator gear (116), a wobble plate (114), and an output plate (118). The stator gear has a stator axis (154) as a central axis, and a plurality of stator teeth (132). The wobble plate has a wobble axis, a plurality of face teeth (128), and a plurality of wobble teeth (130), and is disposed such that the wobble axis makes a non-zero angle with the stator axis. The output plate includes a plurality of output teeth and is substantially aligned with the stator axis. At least two of the pluralities of teeth are configured to engage with each other in a self-aligning manner such that the wobble angle remains constant as the wobble plate nutates around the stator gear.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to wobble plate drives. More particularly, embodiments of the present disclosure relate to systems and methods for adjusting torque using an elliptically engaging gear system. [Background technology]

[0002] By using two or more gears, a mechanical advantage can be created through gear ratios. Various gear arrangements can be configured so that one revolution of the first gear causes one more or less revolution of the second gear in the same amount of time. In some applications, it may be desirable to have a motor with a very high gear ratio and minimal gear reduction.

[0003] Nucleation plate drives have long been considered a promising approach for achieving compact, high-gear ratio drives. In a nutation plate drive, one gear, e.g., a rotor gear, nutates around another gear, e.g., a stator gear. As used herein, the terms "nutate" or "nutation" refer to a wobble, sway, or circular rocking motion. The rotor gear is typically supported by a shaft or pivot that maintains gear tooth alignment. If the number of teeth on the rotor gear differs from the number of teeth on the stator gear by one, the system has a gear ratio equal to the number of teeth on the stator gear.

[0004] In reality, an efficient and effective nutation plate drive system has proven difficult to achieve because the forces acting within the system can cause the mechanism to disengage, bind, or jam. , over-constraint due to pivots, or inefficiencies due to friction, are often Because it occurs. Summary of the Invention

[0005] The self-aligning nutation plate drive device includes a stator gear, a nutation plate, and an output plate. The stator gear has a stator axis as a central axis and a plurality of stator teeth arranged on an inner cylindrical surface. The nutation plate has a nutation axis, an engagement surface perpendicular to the nutation axis, a plurality of surface teeth on the engagement surface, and a plurality of nutation teeth arranged along the outer periphery of the nutation plate and configured to engage with the stator teeth. The output plate includes a plurality of output teeth configured to engage with the surface teeth.

[0006] The nutation plate is positioned such that the nutation axis forms a non-zero nutation angle with respect to the stator axis, and the output plate is substantially aligned with the stator axis, and at least two of the sets of teeth are configured to engage each other in a self-aligning manner so that the nutation angle remains constant as the nutation plate nutates around the stator gear.

[0007] A method of operating a self-aligning nutation plate drive includes providing a stator gear, a nutation plate, and an output plate. The method further includes engaging a plurality of stator teeth of the stator gear with a plurality of nutation teeth of the nutation plate in a self-aligning manner. The method further includes engaging a plurality of face teeth of the nutation plate with a plurality of output teeth of the output plate in a self-aligning manner. Finally, the method includes nutating the nutation plate around the periphery of the stator gear.

[0008] The present disclosure discloses various devices and methods of use. In some embodiments, a nutation plate drive device can include an input plate, a nutation plate, and a stator. In some embodiments, the drive device can include a motor, a nutation plate, a stator, and an output plate. In some embodiments, the nutation plate, the stator gear, and the input plate or the output plate can each include a set of teeth configured to engage with each other in a self-aligning manner.

[0009] The features, functions, and advantages may be realized individually in various embodiments of the present disclosure, but may also be combined with one another in other embodiments, and further details will become apparent from the following description and by reference to the drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded isometric view illustrating an exemplary tumbling plate drive apparatus according to aspects of the present disclosure. [Figure 2] FIG. 2 is an enlarged bottom view showing a portion of the input plate of the nutation plate drive device of FIG. 1. [Figure 3] 2 is an enlarged top view showing a portion of the stator gear of the nutation plate drive device of FIG. 1. FIG. [Figure 4] FIG. 10 is an exploded isometric front view of another exemplary tumbling plate drive apparatus according to aspects of the present disclosure. [Figure 5] FIG. 5 is an exploded isometric rear view of the nutation plate drive mechanism of FIG. [Figure 6] FIG. 5 is an isometric view of the nutation plate of the nutation plate drive of FIG. [Figure 7] 5 is a cross-sectional view of the nutation plate drive device of FIG. 4 taken along a plane parallel to the rotation axis of the device. FIG. [Figure 8] 8 is a cross-sectional view of the nutation plate drive device of FIG. 4 along a plane rotated 45 degrees from the plane of FIG. 7. [Figure 9] FIG. 10 is an isometric view of a schematic of a nutation plate and motor according to aspects of the present disclosure. [Figure 10] FIG. 10 is an exploded isometric diagrammatic view of the motor of FIG. [Figure 11] 10 is a flowchart illustrating an exemplary method of use of a tumbling plate driver according to aspects of the present disclosure. [Figure 12] 10 is a flowchart illustrating another exemplary method of use of a tumbling plate driver according to aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Summary> Various embodiments of a self-aligning wobble plate drive having a nutation plate and a stator are described below and illustrated in the accompanying drawings. Unless otherwise specified, the nutation plate drive and / or its various components may, but need not, include at least one of the structures, components, functions, and / or variations thereof described, illustrated, and / or incorporated herein. Additionally, other nutation plate drives may, but need not, include the structures, components, functions, and / or variations thereof described, illustrated, and / or incorporated herein in connection with this disclosure. The following description of various embodiments is merely exemplary and is not intended to limit the present disclosure, its applications, or uses. Additionally, advantages provided by the embodiments are described below, but these are exemplary, and not all embodiments necessarily provide the same or similar advantages.

[0012] <Examples, parts and alternatives> The following sections describe exemplary tumbling plate drives and related systems and methods.

[0013] Examples in these sections describe selected aspects of the present disclosure and / or methods. The examples in these sections are for illustrative purposes and should not be construed as limiting the scope of the entire disclosure. Each section may include one or more different inventions and / or background or related information, functionality and / or structure.

[0013] Example 1 One embodiment of a self-aligning virtual elliptical drive, or nutation plate drive, can be seen in FIG. 1 and generally designated 10. Drive 10 includes an input plate 12, a nutation plate 14, and a stator gear 16. Input plate 12, also referred to as the output plate in some uses of the nutation plate drive, defines an axis of rotation 20 about which stator gear 16 is centered. Nucleation plate 14 has a nutation axis 22 disposed at a non-zero angle relative to the axis of rotation. This angle is referred to as the wobble angle.

[0014] Nucleation plate 14 has a substantially flat lower surface 24 and an upper engaging surface 26, and includes a plurality of surface teeth 28. Surface teeth 28 are disposed on upper engaging surface 26. A plurality of nutation teeth 30 are also disposed along the periphery of nutation plate 14 between surfaces 24 and 26 in a plane perpendicular to the nutation axis. The nutation teeth extend from surface 26 toward surface 24 parallel to the nutation axis.

[0015] Nucleation plate 14 is disposed between input plate 12 and stator 16. Lower surface 24 is perpendicular to the nutation axis and faces generally toward stator 16, while engagement surface 26 is parallel to the lower surface and defines a surface facing generally toward input plate 12. Nucleation teeth 30 and surface teeth 28 extend in opposite directions parallel to nutation axis 22.

[0016] Input plate 12 has an annular input surface 36 on its outer portion, best seen in FIG. 2. Input surface 36 may be frusto-conical. That is, the annular input surface 36 is inclined relative to a plane perpendicular to the rotation axis 20, and all points included in the annular input surface lie on a frusto-conical line 38 that can be extended to pass through an apex located below input plate 12 on the rotation axis. When the above elements are assembled into a drive unit, the apex of the frusto-conical annular input surface 36 is located near the center of gravity of nutation plate 14.

[0017] A plurality or set of input teeth 34 are disposed on an annular input face 36. Any suitable number of input teeth 34 may be used. Each input tooth 34 includes two drive faces 40, 42, each of which may be planar, comprised of multiple planar faces, or comprised of one or more surfaces having curvature.

[0018] As shown in Figure 1, the upper engagement surface 26 of the nutation plate 14 has an annular nutation surface 64 on its outer portion, similar to the annular input surface 36 shown in Figure 2. That is, the annular nutation surface 64 is inclined with respect to a plane perpendicular to the nutation axis 22, and all points included in the annular nutation surface lie on a truncated cone line that can be extended to pass through the apex of the truncated cone located on the nutation axis. The apex of the truncated cone of the annular nutation surface 64 coincides with the center of gravity of the nutation plate 14. In other embodiments, the nutation surface may have a different shape.

[0019] The plurality or set of flank teeth 28 are arranged on an annular nutation surface 64. Any suitable number of flank teeth 28 can be selected, and the number of flank teeth can be greater than, less than, or equal to the number of input teeth 34. In the illustrated embodiment, the number of flank teeth 28 is equal to the number of input teeth 34. Each flank tooth includes two driven surfaces, which may be planar, comprised of multiple planar surfaces, or comprised of one or more surfaces having curvature.

[0020] The nutation plate 14 is configured to engage with the input plate 12. More specifically, The flank teeth 28 are configured to engage with the input teeth 34. When the input plate rotates in a predetermined rotational direction, the drive surfaces of the input teeth engage with the driven surfaces of the flank teeth. That is, contact forces can be applied from the input plate to the nutation plate through the interaction of the drive surfaces of the multiple input teeth and the driven surfaces of the multiple flank teeth. These contact forces cause the nutation plate to rotate in the same predetermined rotational direction.

[0021] In this embodiment of the drive 10, the input plate 12 and the nutation plate 14 interact and rotate according to a 1:1 gear ratio, i.e., for every full rotation of the input plate, the nutation plate also rotates exactly one full rotation. Other gear ratios can be selected, resulting in different rotational speeds.

[0022] The nutation plate 14 and input plate 12 may be configured so that any contact force between them is directed in the direction of a tangent to a circle lying in a plane perpendicular to the axis of rotation. By configuring the nutation plate and input plate so that the contact force between them is directed in this direction, eccentric forces can be avoided. Eccentric forces can cause the surface teeth 28 to disengage from the input teeth 34 or can cause the center of gravity of the nutation plate to wobble, thereby causing undesirable vibrations in the drive system.

[0023] The complementary frustoconical shapes of input face 36 and nutation face 64 result in input teeth 34 engaging surface teeth 28 at an angle such that tooth-to-tooth contact forces act to return input plate 12 and nutation plate 14 to alignment in the event of vibration or displacement of drive 10. Thus, input teeth 34 and nutation face teeth 28 engage in a self-centering manner, maintaining a constant nutation angle as the input plate and nutation plate rotate.

[0024] 1, the stator gear 16 has a base 48 that includes an inner cylindrical surface 50 and a stator tooth base 52. The base 48 may include mounting points configured to operatively couple the stator 16 to a mounting member of any device that uses the drive device 10 (e.g., a device incorporating the drive device 10 therein). The stator 16 may be fixed relative to the device. The stator gear defines a stator axis 54 that is substantially aligned with the axis of rotation 20.

[0025] The stator 16 has an interior space 56 defined in part by the inner cylindrical surface 50. The interior space 56 may be configured to accommodate a portion or all of the nutation plate 14, as described in more detail below.

[0026] The stator teeth 32 may be formed to connect to either or both of the inner cylindrical surface 50 and the stator tooth base 52. In the embodiment of Figure 1, the stator teeth extend from the inner cylindrical surface into the interior space 56 in a radial direction toward the rotation axis. In addition, the stator teeth also extend from the stator tooth base 52 in an axial direction parallel to the rotation axis. The number of stator teeth can be selected as desired depending on the application and the desired gear ratio.

[0027] FIG. 3 is a top view of the stator gear 16, showing some of the stator teeth 32. Each of the stator teeth has a proximal end and a distal end relative to the rotational axis 20. The distal end of the stator tooth is connected to the inner cylindrical surface 50, for example. Each tooth has a first engagement surface 66 and a second engagement surface 68 on the opposite side of the tooth. Each engagement surface may be flat, comprised of multiple planes, or comprised of one or more surfaces with curvature. For example, one or both of the engagement surfaces 66, 68 of the stator teeth 32 may be defined by a compound involute curve of a circle and an ellipse, as described above. Alternatively, the curve may be the projection of an imaginary ellipse onto the tooth location for all angles between 0 and 2π radians.

[0028] Each of the plurality of stator teeth 32 is wedge-shaped. Specifically, the first engagement surface 66 defines a line 70 extendable through the axis of rotation. Line 70 passes through the center of gravity of the nutation plate when both the nutation plate and the stator gear are coupled together in a drive device. The second engagement surface 68 also defines a line 72 extendable through the axis of rotation. Line 72 also passes through the center of gravity of the nutation plate when both the nutation plate and the stator gear are coupled together in a drive device.

[0029] Each of the plurality of stator teeth 32 includes an engagement portion and a support base. The engagement portion includes the first and second engagement surfaces described above. The support base connects the engagement portion to the stator tooth base 52. The stator teeth may be supported by other structures or may be connected to the stator tooth base in any suitable manner.

[0030] As shown in FIG. 1 , a plurality of nutation teeth 30 are disposed along the periphery of the nutation plate 14 between the lower surface 24 and the upper engagement surface 26 in a plane perpendicular to the nutation axis 22. The nutation teeth extend radially away from the nutation axis from the outer cylindrical surface 58 of the nutation plate. In addition, the nutation teeth extend axially along the nutation axis from a nutation tooth base 60. The nutation tooth base may be a generally annular member connected to or integral with the nutation plate. Connecting the nutation teeth to either the cylindrical surface or the nutation tooth base, or both, can provide physical support or a degree of rigidity to the plurality of nutation teeth. Any suitable number of nutation teeth 30 can be selected, and the number of nutation teeth may be greater than, less than, or equal to the number of stator teeth 32.

[0031] Similar to the stator tooth 32 shown in FIG. 3, each nut tooth 30 has a first engagement surface and a second engagement surface on the opposite side of the tooth. Each engagement surface may be planar, comprised of multiple planes, or comprised of one or more surfaces with curvature. One or both of the engagement surfaces of a nut tooth 30 may be defined by a compound involute curve of a circle and an ellipse, as previously described. Alternatively, the curve may be the projection of an imaginary ellipse onto the tooth position for all angles between 0 and 2π radians.

[0032] Each of the plurality of nutation teeth is wedge-shaped, such that the first engagement surface defines a first line extendable through the nutation axis, and the second engagement surface defines a second line extendable through the nutation axis, both of which pass through the center of gravity of the nutation plate.

[0033] Additionally, each nutation tooth 30 includes an engagement portion and a support base. The engagement portion includes a first engagement surface and a second engagement surface. The support base connects the engagement portion to the nutation tooth base 60. The nutation tooth may be supported by other structure or may be connected to the nutation tooth base in any suitable manner.

[0034] The nutation plate 14 is configured to engage with the stator gear 16. More specifically, the nutation teeth 30 are configured to engage with the stator teeth 32. When the input plate 12 rotates in a first direction, first engagement surfaces of the nutation teeth may engage with first engagement surfaces of the stator teeth. That is, contact forces may be applied from the stator gear to the nutation plate through interaction between the first engagement surfaces of the plurality of stator teeth and the first engagement surfaces of the plurality of nutation teeth. These contact forces cause the nutation plate to rotate in a first rotational direction and nutate in a first nutation direction.

[0035] Generally, the stator gear has n stator teeth and the nutation plate has m nutation teeth, where n and m are integers that are different by 1 or more, and typically are integers that are different by 1. As the nutation plate nutates around the periphery of the stator gear, each of the multiple nutation teeth rotates during one nutation. , may engage one of the stator teeth. If there is one more stator tooth than nutation tooth, the nutation plate rotates slightly during each nutation.

[0036] Specifically, the nutation plate rotates 1 / m of a full revolution during one nutation of the nutation plate. In other words, the nutation plate completes one full nutation when it rotates 1 / m of a full revolution, possibly through interaction with the input plate. Thus, the nutation plate and the stator gear may interact according to an m:1 gear ratio. For every m nutations of the nutation plate, the nutation plate completes exactly one revolution. Thus, the gear ratio of the disclosed system can be determined by the number of teeth, m, of the nutation plate and the number of teeth, n, of the stator gear.

[0037] The nutation plate and stator gear may be configured so that any contact force therebetween is directed in a direction tangent to a circle lying in a plane perpendicular to the axis of rotation, e.g., substantially perpendicular to the nutation axis 22 and to a radial line extending from the contact point between the nutation tooth 30 and the stator tooth 32 to the nutation axis 22.

[0038] The wedge shapes of the stator teeth 32 and nutation teeth 30 define complementary conical surfaces that provide an angular engagement such that the contact force created by the tooth engagement acts to return the nutation plate 14 to alignment with the stator gear 16 in the event of vibration or displacement of the drive 10. Thus, the teeth engage in a self-centering manner, maintaining a constant nutation angle as the nutation plate nutates along the stator.

[0039] The nutation plate 14 and the stator gear 16 are substantially circular, but due to their different orientations, the projection of the nutation plate onto the stator results in an ellipse. The nutation teeth 30 and the stator teeth 32 may be contoured by projecting this imaginary ellipse onto the tooth locations. The elliptical projection of the nutation plate 14 onto the stator 16 limits it to non-eccentric rotation. Allowing eccentric motion would generate large unbalanced forces and may result in unacceptable system performance.

[0040] The nutation plate drive is a mechanically constrained system that follows Euler's equation for the rotating inertial reference frame defined by the nutation of the plate. It can be understood that Euler's z-axis equation To defeat.

number

[0041] The nutation teeth 30 and stator teeth 32 can be configured to mechanically constrain the movement of the nutation plate 14, for example, by defining the tooth engagement surfaces as a compound involute curve of a circle and an ellipse. In this configuration, the maximum rotational speed possible at the nutation plate is less than or equal to the rotational speed required to satisfy the solution to Euler's equations. As the nutation plate accelerates, a force acts to increase the nutation angle. This force is counteracted by contact with the input plate 12, maintaining a constant nutation angle.

[0042] In other words, when the nutating nutation plate is subjected to torque due to engagement with the input plate, the nutation angle tends to increase. The nutation plate is spaced a predetermined distance from the stator gear to constrain it against rotation, so that as the nutation plate nutates around the stator, the nutation angle remains constant and no part of the nutation plate is more than the predetermined distance from the stator gear.

[0043] An exemplary nutation plate drive in this disclosure can either store and absorb input torque or output a limited amount of the stored torque. In the first case, input teeth 34 of input plate 12 engage face teeth 28 of nutation plate 14, causing the plate to rotate. Nucleation teeth 30 of the nutation plate engage stator teeth 32 of stator gear 16, causing nutation of the nutation plate. The nutation plate stores and absorbs input torque as nutation.

[0044] The nutation plate drive can be thought of as an imaginary ellipse formed by projecting the nutation plate onto the stator. The nutation plate 14 and the stator 16 generally have one contact point. The periphery of the imaginary ellipse defines a continuous contact line between the elliptical mating nutation plate and the stator. The line of contact can be defined in three dimensions. The shape of the imaginary ellipse can remain unchanged as the nutation plate nutates through an angle four times the angle between the nutation axis 22 and the rotation axis 20. It is simply the rotational frame of the contact line, defined by Euler's equation, that advances with nutation. Each point on the contact line is determined by a geometrically distorted compound involute function. The function corresponds to a geometrically distorted involute function, which is symmetric under both rotation and nutation. This allows for continuous energy transfer to and from the virtual ellipse.

[0045] The imaginary ellipse remains stationary as the inertial frame rotates, and all points on the contact line rotate with constant angular velocity in their respective horizontal planes. During nutation, if we observe a point located at the radial edge of the nutation plate 14, this point undergoes vertical motion with a constantly changing velocity. This change in velocity may require a constant acceleration relative to the inertia of the nutation plate, so that the kinetic energy input to the system is absorbed.

[0046] In the second case, the nutation plate drive outputs stored torque, causing rotation of the nutation plate to rotate the input plate. In this case, no external torque is applied to the input plate 12 during rotation and nutation of the nutation plate 14.

[0047] As the nutation plate rotates in a first rotational direction, the first driven surfaces of the face teeth can engage with the first drive surfaces of the input teeth. That is, through the interaction of the first driven surfaces of the plurality of face teeth with the first drive surfaces of the plurality of input teeth, the nutation plate applies contact forces to the input plate. These contact forces cause the input plate to rotate in the first direction. In other words, the input plate can be considered an output plate.

[0048] <Example 2> Another embodiment of a self-centering virtual elliptical drive can be seen from different angles in Figures 4 and 5 and is generally designated by the numeral 110. Drive 110 includes an input motor 112, a nutation plate 114, a stator gear 116, and an output plate 118. Motor 112 defines an axis of rotation 120 about which stator gear 116 and output plate 118 are disposed. Nunching plate 114 is disposed at a non-zero angle relative to the axis of rotation.

[0049] The nutation plate 114 has a substantially flat rear surface 124 and a front surface 126, and includes a plurality of surface teeth 128 and a plurality of nutation teeth 130. The surface teeth 128 are provided on the front surface 126. The nutation teeth 130 are provided along the periphery of the nutation plate between the surfaces 124 and 126, in a plane perpendicular to the nutation axis. The nutation teeth 130 and the surface teeth 128 are provided on the nutation plate (shown in FIG. 6). It extends in the same direction as the head axis 122 .

[0050] In the assembled drive 110, the motor 112 engages the rear surface 124 of the nutation plate 114, thereby nutating the nutation plate along the stator 116. The stator, sometimes referred to as a stator gear, includes a plurality of stator teeth 132 configured to engage with the nutation teeth 130, thereby rotating the nutation plate. The output plate 118 includes a plurality of output teeth 134 configured to engage with the surface teeth 128, thereby rotating the nutation plate. In this manner, the motor 112 can rotate the output plate 118 with a torque determined by a first gear ratio between the nutation plate 114 and the stator 116 and a second gear ratio between the nutation plate 114 and the output plate 118.

[0051] 4 and 5, the input motor 112 is an electric motor having a substantially flat surface 136 perpendicular to the axis of rotation 120 and includes a first cartridge bearing 138 and a second cartridge bearing 140 coupled to the flat surface. The bearings 138 and 140 are best seen in FIG. 4. The first bearing may be angularly spaced 89 degrees from the second bearing as measured about the axis of rotation 120. The bearings may be coupled adjacent a radial edge of the flat surface 136.

[0052] Bearings 138, 140 extend from planar surface 136, with either bearing 138 or bearing 140 contacting rear surface 124 of the nutation plate. This point of contact may be located 45 degrees from the closest point of the motor and nutation plate as measured about the axis of rotation. The bearings may be configured to make rolling contact with rear surface 124 of nutation plate 114, thereby engaging the nutation plate to create nutation.

[0053] In another embodiment, not shown, a single rounded protrusion (rather than two protrusions) may be formed on the flat surface 136 of the motor 112. This rounded protrusion may contact the nutation plate 114 at a point spaced apart by an angle of 45 degrees from the closest point, as measured around the axis of rotation. Other embodiments may include two protrusions spaced apart by an angle between 80 and 100 degrees, not necessarily exactly 89 degrees. Still other embodiments may include three or more protrusions extending from the flat surface 136.

[0054] Regardless of the number of rounded protrusions, a lubricant may be disposed between the motor 112 and the nutation plate 114 to reduce friction between the rounded protrusions and the nutation plate rear surface 124. Additionally, the protrusions may be any shape and may include any feature that contributes to providing low-friction rolling engagement of the protrusions with the nutation plate 114.

[0055] As shown in Figure 6, the nutation plate 114 may be disk-shaped, having a rear surface 124, a front surface 126, and a central axis or nutation axis 122. The nutation plate 114 is aligned so that the nutation axis 122 forms a non-zero angle with respect to the rotation axis 120. The rear surface 124 may be perpendicular to the rotation axis, for example, and the front surface 126 may define a plane parallel to the rear surface. As shown in Figures 4-5, the rear surface 124 generally faces toward the input motor 112, and the front surface 126 generally faces away from the motor.

[0056] 4-5, a plurality of nutation teeth 130 are provided along the periphery of the nutation plate 114 between the rear surface 124 and the front surface 126 in a plane perpendicular to the nutation axis 122. The nutation teeth extend radially away from the nutation axis from the outer cylindrical surface 158 of the nutation plate. The nutation teeth may also extend axially along the nutation axis from a nutation tooth base 160. The nutation tooth base may be, for example, a generally annular member connected to or integrally formed with the nutation plate. The multiple nut teeth may extend from both the cylindrical surface 158 and the nut tooth base 160. By connecting the nut teeth to either the cylindrical surface or the nut tooth base, or both, the multiple nut teeth may be provided with physical support or a degree of rigidity. The number of nut teeth 130 may be selected as desired.

[0057] Each nutation tooth 130 has a first engagement surface and a second engagement surface on the opposite side of the tooth. Each engagement surface may be planar, comprised of multiple planes, or comprised of one or more surfaces with curvature. One or both of the engagement surfaces of a nutation tooth 130 may be defined by a compound involute curve of a circle and an ellipse, as described in more detail below. Alternatively, the curve may be the projection of an imaginary ellipse onto the tooth position at all angles between 0 and 2π radians.

[0058] Each nut tooth 130 also includes an engagement portion and a support base. The engagement portion includes a first engagement surface and a second engagement surface. The support base connects the engagement portion to the nut tooth base 160.

[0059] For each of the plurality of nut teeth 130 and stator teeth 132, one or both of the first and second engagement surfaces may be defined by a compound involute curve of a circle and an ellipse. That is, the curve of the second engagement surface may be defined by Equation 2 below.

number

[0060] Alternatively, the curve of the second engagement surface may be defined by Equation 3 below:

number

[0061] Equation 3 above may be normalized to the radius of the nutation plate. The curve of the second engagement surface may be the projection of an imaginary ellipse onto the tooth position at all angles between 0 radians and 2π radians. The curve of the first engagement surface may be a mirror image of the curve of the second engagement surface, inverted about a plane that passes through the apex of the tooth and contains the axis of rotation. The first engagement surface and the second engagement surface may also be smoothly connected at the apex of each tooth. Thus, the cross-sectional shape of the tooth is defined by a compound involute curve of a circle and an ellipse.

[0062] As shown in FIG. 6 , the front surface 126 of the nutation plate 114 includes an annular nutation surface 164, which, in the illustrated embodiment, is a frustoconical surface. That is, the annular nutation surface 164 is inclined relative to a plane perpendicular to the nutation axis 122, and every point on the annular nutation surface includes a frustoconical line that can be extended to a frustoconical apex that lies on the nutation axis. The apex of the frustoconical apex of the annular nutation surface 164 coincides with the center of gravity of the nutation plate 114. In other embodiments, the nutation surface may have a different shape.

[0063] A plurality or group of flank teeth 128 are arranged on the annular nutation surface 164. The number of flank teeth 128 can be selected arbitrarily and may be greater than, less than, or equal to the number of output teeth 134. In the illustrated embodiment, the number of flank teeth 128 is the same as the number of output teeth 134. Each flank tooth includes two drive surfaces, which may be planar, comprised of multiple planes, or comprised of one or more surfaces with curvature.

[0064] 4-5, the stator gear 116 has a base 148 that includes an inner cylindrical surface 150 and a stator tooth base 152. The base 148 may include mounting points configured to operably couple the stator 116 to a mounting member of any device that uses the drive device 110. The stator 116 is stationary relative to the device. The stator gear defines a stator axis 154 that is substantially aligned with the rotation axis 120 and, therefore, with the output shaft. The stator is disposed between the nutation plate 114 and the output plate 118.

[0065] The stator 116 has an interior space 156 defined in part by the inner cylindrical surface 150. The interior space 156 may be configured to accommodate a portion or all of the nutation plate 114, as described in more detail below.

[0066] The stator teeth 132 may be provided on either or both of the inner cylindrical surface 150 and the stator tooth base 152. The stator teeth extend from the inner cylindrical surface into the interior space 156 along a radial direction toward the rotation axis. In addition, the stator teeth also extend axially from the stator tooth base 152 along the rotation axis. The number of stator teeth can be selected arbitrarily depending on the application and the desired gear ratio. The number of stator teeth may be more than, less than, or the same as the number of nut teeth 130.

[0067] Each of the plurality of stator teeth can have a proximal end and a distal end relative to the axis of rotation 120. The distal end of the stator tooth can be connected to the inner cylindrical surface 150. Each tooth has a first engagement surface and a second engagement surface on an opposite side of the tooth. Each engagement surface can be flat, comprised of multiple flat surfaces, or comprised of one or more surfaces with curvature.

[0068] The engagement surface of one or both of the stator teeth 132 may be defined by a compound involute curve of a circle and an ellipse, as previously described, or the curve may be the projection of an imaginary ellipse onto the tooth position at all angles between 0 and 2π radians.

[0069] Each of the plurality of stator teeth 132 includes an engagement portion and a support base. The engagement portion includes a first engagement surface and a second engagement surface. The support base connects the engagement portion to the stator tooth base 152.

[0070] 4-5, the output plate 118 includes a plurality of output teeth 134 arranged on an annular output surface 162. The output plate 118 also has an output shaft that is substantially aligned with the rotational axis 120.

[0071] 5, the output surface 162 is frusto-conical. That is, the annular output surface 162 is inclined relative to a plane perpendicular to the rotation axis 120, and every point on the annular output surface includes a frusto-conical line that can be extended to the frusto-conical apex, which is located on the rotation axis and forward of the output plate 118. When the above-described elements are assembled into the drive unit 110, the apex of the frusto-conical annular output surface 162 coincides with the center of gravity of the nutation plate 114. In other embodiments, the output surface may have a different shape, such as a cylinder or a frusto-conical shape with another apex.

[0072] The number of output teeth 134 can be selected arbitrarily and may be greater than, less than, or equal to the number of surface teeth 128. Each output tooth may include two driven surfaces. Each driven surface may be planar, comprised of multiple planar surfaces, or comprised of one or more surfaces with curvature. It may be possible.

[0073] 7-8 are cross-sectional views of drive unit 110, showing motor 112, nutation plate 114, stator gear 116, and output plate 118 in an assembled state. The motor and output plate are aligned along stator axis 154; that is, the rotation axis, output axis, and stator axis are substantially aligned. The nutation plate and nutation axis 122 can be positioned at any desired and suitable non-zero angle relative to the stator axis. As nutation plate 114 nutates around stator 116 and output plate 118, the center of gravity of the nutation plate remains substantially fixed.

[0074] FIG. 8 is a cross-sectional view in a plane rotated 45 degrees about stator axis 154 from the plane of the cross section of FIG. 7, the angles in each view being exaggerated to more clearly show the relationships between the parts.

[0075] The nutation plate 114 is configured to engage with the stator gear 116. More specifically, the nutation teeth 130 are configured to engage with the stator teeth 132. When the motor 112 rotates in a first direction, first engagement surfaces of the nutation teeth may engage with first engagement surfaces of the stator teeth. That is, the interaction of the first engagement surfaces of the plurality of stator teeth with the first engagement surfaces of the plurality of nutation teeth may impart contact forces to the nutation plate by the stator gear. These contact forces cause the nutation plate to rotate in the first direction and nutate in a first nutation direction.

[0076] Typically, the stator gear has n stator teeth and the nutation plate has m nutation teeth, where n and m are integers that differ by 1 or more, and typically by 1. As the nutation plate nutates around the periphery of the stator gear, each of the nutation teeth may engage one of the stator teeth during a single nutation. If there is one more stator tooth than nutation teeth, the nutation plate may rotate only slightly during a single nutation.

[0077] Specifically, the nutation plate may rotate 1 / m of a full revolution during one nutation of the nutation plate. In other words, when the nutation plate rotates 1 / m of a full revolution, possibly through interaction with the motor, the nutation plate completes one full nutation. Thus, the nutation plate and the stator gear may interact according to an m:1 gear ratio. The nutation plate may rotate exactly one time for every m nutations. Therefore, the gear ratio of the system of the present disclosure may be determined by the number of teeth, m, of the nutation plate and the number of teeth, n, of the stator gear.

[0078] The nutation plate and stator gear may be configured so that any contact force therebetween is oriented tangentially to a circle lying in a plane perpendicular to the axis of rotation, e.g., substantially perpendicular to the nutation axis 122 and substantially perpendicular to a radial line extending from the contact point between the nutation tooth 130 and the stator tooth 132 to the nutation axis 122.

[0079] The nutation plate 114 and the stator gear 116 may be substantially circular, but may be shaped such that their different orientations result in an elliptical projection of the nutation plate onto the stator. The nutation teeth 130 and the stator teeth 132 may be contoured by projecting this imaginary ellipse onto the tooth locations. The elliptical projection of the nutation plate 114 onto the stator 116 is thereby constrained to non-eccentric rotation. Allowing eccentric motion would generate large unbalanced forces, potentially resulting in unacceptable system performance.

[0080] The nutation plate 114 is rotated by the engagement of the surface teeth 128 with the output teeth 134. 18. When the nutation plate rotates in a first rotational direction, a first drive surface of the face teeth can engage a first driven surface of the output teeth. That is, the interaction of the first drive surfaces of the plurality of face teeth with the first driven surfaces of the plurality of output teeth can impart contact forces to the output plate by the nutation plate. These contact forces cause the output plate to rotate in the first direction. When the nutation plate rotates in a second direction, a contact force between a second drive surface of the face teeth and a second driven surface of the output teeth can cause the output plate to rotate in the second rotational direction.

[0081] In the exemplary nutation plate drive 110, the output plate and the nutation plate have the same number of teeth; that is, the number of output teeth equals the number of face teeth. Thus, in the illustrated embodiment, the output plate and the nutation plate interact and rotate according to a 1:1 gear ratio; that is, for every full rotation of the nutation plate, the output plate also rotates exactly one full rotation. Other choices for the number of output teeth and face teeth are possible, resulting in other output gear ratios.

[0082] The nutation plate 114 and the output plate 118 may be configured so that any contact force therebetween is oriented tangentially to a circle that lies in a plane perpendicular to the axis of rotation, for example, substantially perpendicular to the nutation axis 122 and substantially perpendicular to a radial line extending from the contact point between the face tooth 128 and the output tooth 134 to the nutation axis 122.

[0083] By configuring the nutation plate and the output plate so that the contact force between them is oriented in this manner, eccentric forces can be avoided that could cause the face teeth to disengage from the output teeth or could cause the center of gravity of the nutation plate to wobble, resulting in undesirable vibrations in the drive system.

[0084] The nutation plate 114 may have a 0-degree position or 0-degree point 142 on the nutation plate that is the farthest position or point from the output plate 118, as measured in a direction parallel to the rotation axis 120. The nutation plate 114 is closest to the motor 112 at the 0-degree position shown in FIG. 7 . The nutation plate 114 may have a 90-degree position or 90-degree point that is one-quarter of the way around the nutation plate in the first nutation direction from the 0-degree position. For example, from a vantage point above the nutation plate near the output plate, the 90-degree position is 90 degrees counterclockwise around the nutation plate. Continuing along the nutation plate's periphery, opposite the 0-degree position 142, is a 180-degree position or 180-degree point 144. The 180-degree position may be the point where the nutation plate is closest to the output plate and stator gear, and farthest from the motor. The 270 degree position or point is opposite the 90 degree position on the nutation plate.

[0085] The motor 112 may be positioned so that the 0-degree point 142 contacts the flat surface 136 between the motor's bearings 138, 140 (not shown) at any given moment, as shown in FIG. 7. At that same moment, only one of the bearings 138 and 140 may contact a point 146 on the rear surface 124 of the nutation plate 114, as shown in FIG. 8. The motor rotates the bearing about the stator axis 154, thereby nutating the nutation plate 114 around the stator gear 116 such that the nutation axis 122 precesses about the stator axis. Thus, the contact point 146 between the bearing and the nutation plate 114 may be forward of the 180-degree point 144.

[0086] When the motor rotates in a first direction, bearing 138 contacts rear surface 124 of the nutation plate at a point between 0 degree position 142 and 270 degree position, and engagement with the nutation plate may cause the nutation plate to nutate in the first direction. Figure 8 shows bearing 138 in such a case. When the motor rotates in a second direction, bearing 140 contacts rear surface 124 of the nutation plate at a point between 0 degree position 142 and 270 degree position. and the 90 degree position, and engagement with the nutation plate may cause the nutation plate to nutate in a second direction.

[0087] During use of the drive 110, the nutation plate 114 will typically nutate and rotate. The nutation plate may be configured to nutate around the periphery of the stator gear 116, motor 112, and / or output plate 118. As the nutation plate nutates in a first nutation direction, the 0-degree position of the nutation plate moves toward the current 90-degree position, so that after nutating one-quarter of a full nutation, the 90-degree position becomes the 0-degree position, the 180-degree position becomes the 90-degree position, and so on. Additionally, the nutation plate does not have to rotate at the same rate as the nutation. That is, as the nutation plate completes one full nutation, the 0-degree position may move around the entire circumference of the nutation plate. During this same time, the nutation plate may rotate less than one full rotation. The rotation rate may be determined by the nutation rate and the gear ratio between the nutation teeth 130 and the stator gear 116.

[0088] At any instant during nutation of the nutation plate, the nutation teeth 130 may engage with one-quarter of the stator gear's stator teeth 132. This engagement may be in the form of rolling contact, where the primary engagement surfaces roll against each other. This rolling contact contrasts with many standard gear engagements, where opposing surfaces of gear teeth engage through sliding contact. Generally, given the same two surfaces, rolling contact results in much less friction between the two surfaces than sliding contact.

[0089] The nutation teeth 130 may contact the stator teeth 132 only between the 0-degree and 270-degree positions during the first nutation direction. This contact may be limited to rolling contact between the nutation teeth and portions of the stator teeth. Thus, the nutation plate can nutate around the stator with less friction than would be the case with sliding contact. This configuration allows for efficient conversion of nutation motion or energy into rotational motion or energy.

[0090] Similarly, the flank teeth 128 may engage with one-quarter of the output teeth 134 of the output plate at any instant as the nutation plate nutates. When the nutation plate nutates in a first direction, the flank teeth and the output teeth may engage between the 180-degree position 144 and the 90-degree position. This engagement allows the nutation plate 114 to rotate the output plate 118 in the same direction as the nutation plate. In the illustrated embodiment, if the gear ratio between the flank teeth 128 and the output teeth 134 is 1, the output plate 118 may also rotate at the same speed as the nutation plate 114. Therefore, the rotation of the motor 112 can be transmitted to the output plate 118 with a higher torque.

[0091] Example 3 9 illustrates another embodiment of a self-centering virtual elliptical drive, generally designated 210, and its motor 212 and nutation plate 214. Because the embodiment of FIG. 9 is similar to nutation plate drive 110 described in Example 2, the description of the various features and advantages of drive 110 will not be repeated in full for drive 210. Similar parts are designated by numbers incremented by 200 from the original numbers.

[0092] The nutation plate 214 includes a nutation axis 222, a substantially flat rear surface, a front surface with a plurality of surface teeth, and a plurality of nutation teeth disposed along the periphery of the nutation plate between the flat surface and the front surface. The surface teeth and nutation teeth are not shown in FIG. 9 but are similar to those shown in, for example, FIG. 6. The nutation plate drive device further includes an output plate with output teeth and a stator with stator teeth. These are not shown in the figures but are as already described in, for example, Example 2 (see FIGS. 4-5).

[0093] Motor 212 has a motor shaft 220. The nutation plate is configured to nutate around the motor's circumference, with the nutation axis precessing about the motor shaft. That is, nutation plate 214 has a mobile point of closest approach 242 to the motor. Mobile point of closest approach 242 moves about motor shaft 220 in the impulse direction indicated by arrow 243.

[0094] In the exemplary drive system 210, nutation of the nutation plate 214 around the periphery of the motor 212 is driven by an electromagnetic force applied to the nutation plate. This force is generated by the motor and applied to the nutation plate at a location forward in the nutation direction 243 from the closest point of travel 242.

[0095] A force indicated by arrow 245 in FIG. 9 is applied to the nutation plate 214 at a leading point 246 that is 90 degrees forward from the closest point of travel 242. Force 245 is an attractive force and The force 245 is a force directed toward the motor 212 or a force along a direction parallel to the motor shaft 220. As the nutation plate nutates and both the 0-degree position 242 and the leading position 246 move around the periphery of the nutation plate, the force 245 also moves around the periphery of the nutation plate. Thus, the force 245 is always applied near the leading position 246 of the nutation plate. In other words, the applied force 245 can be said to precede the closest point of movement in the nutation direction 243. The application of a force to the nutation plate at a position preceding the closest point of movement causes the nutation plate to nutate.

[0096] Force 245 is generated as a result of the material of nutation plate 214 reacting to an electromagnetic field generated by motor 212. The motor includes a permanent magnet and a set of electromagnetic coils. The permanent magnet and the set of electromagnetic coils are configured to cooperate to generate a magnetic field between the motor and the nutation plate. That is, the magnetic field is generated in gap 266 between motor 212 and nutation plate 214. The nutation plate is formed of a magnetically sensitive material configured to react to the magnetic field. The magnetically sensitive material becomes magnetized in the presence of the magnetic field. The nutation plate is subjected to and reacts to forces such as force 245.

[0097] The force applied to the nutation plate may be proportional to the magnetic flux density of the magnetic field between the nutation plate and the motor. To apply the applied force at a translation position preceding closest point of approach 242, the permanent magnet and set of electromagnetic coils are configured to create a magnetic field with a highest magnetic flux density at a translation position ahead of closest point of approach in the nutation direction 243. The electromagnetic coils are configured so that the location of highest magnetic flux density in the magnetic field always precedes closest point of approach during nutation of the nutation plate.

[0098] 10 is an exploded isometric diagrammatic view of motor 212. The motor includes a permanent magnet 268, a motor core 270, a set of responsive pole pieces 272, and a set of electromagnetic coils 274. The relative locations and orientations of the components of motor 212 may be specified with reference to the motor axis. The term "axial" refers to linear directions parallel to motor axis 220. The term "radial" refers to linear directions perpendicular to motor axis 220. The term "circumferential" refers to angular directions about the motor axis, rather than along or away from the motor axis.

[0099] The permanent magnet 268 may have any suitable shape and may be configured to generate any suitable magnetic field. In the illustrated example, the permanent magnet is cylindrical with the motor axis 220 as its axis of symmetry and has a passage 276 extending through the permanent magnet along the motor axis. The permanent magnet 268 may be constructed of any suitable ferromagnetic material. The permanent magnet 268 has north and south poles substantially aligned along the motor axis 220. The magnetic field generated by the permanent magnet may be referred to as the primary magnetic field.

[0100] A motor core 270 is disposed below the permanent magnets 268. The motor core 270 may be formed of a magnetically sensitive material capable of acquiring a magnetic moment when placed in a magnetic field. For example, the motor core 270 may be formed of magnetic steel or iron. The motor core 270 may have any suitable shape. In the illustrated example, the motor core is cylindrical with an axis of symmetry about the motor axis 220 and a radius that matches the radius of the permanent magnets 268. The motor core includes a passage 278 that aligns with a passage 276 through the permanent magnets.

[0101] Motor 212 includes a horizontal spacer 280 positioned between permanent magnets 268 and motor core 270. Horizontal spacer 280 limits the magnetic field transmitted from the permanent magnets to the motor core and helps adjust the magnitude of the magnetic field generated by motor 212.

[0102] A set of magnetically sensitive pole pieces 272 are arranged circumferentially around the motor core 270. The pole pieces 272 can direct the magnetic field within the motor 212 from one component of the motor to another. The pole pieces can be formed of any suitable magnetically sensitive material, such as electromagnetic steel. Any suitable number of pole pieces can be provided. For example, the embodiment shown in FIG. 10 includes 12 pole pieces. The pole pieces can have any suitable shape. For example, the 12 pole pieces shown in FIG. 10 are wedge-shaped and may be referred to as wedge pieces instead of pole pieces. The pole pieces 272 are separated from one another by a set of vertical spacers 282. The vertical spacers help isolate the magnetic fields of the pole pieces located between them.

[0103] The set of magnetically sensitive pole pieces 272 collectively have a top surface area 284. The pole pieces are configured so that the top surface area is a predetermined multiple of the top surface area of ​​the permanent magnet 268. In some embodiments, the top surface area 284 of the pole pieces is three times the top surface area of ​​the permanent magnet.

[0104] A set of electromagnetic coils 274 is arranged along the circumferential direction of the motor core 270 between the motor core 270 and the sensitive pole pieces 272. The set of electromagnetic coils includes a first set of electromagnetic coils and a second set of electromagnetic coils. In the illustrated example, the first set of electromagnetic coils includes three inner electromagnetic coils 286, and the second set of electromagnetic coils includes three outer electromagnetic coils 288. The three outer electromagnetic coils 288 are arranged, for example, between the inner electromagnetic coil 286 and the set of sensitive pole pieces 272. The first and second sets of electromagnetic coils can include any suitable number of coils, for example, two, three, four or more. The number of electromagnetic coils in the first set and the number of electromagnetic coils in the second set do not have to be the same.

[0105] Each of the first set of electromagnetic coils 286 circumferentially overlaps each of adjacent pairs of electromagnetic coils in the second set of electromagnetic coils 288. Each of the second set of electromagnetic coils 288 also circumferentially overlaps each of adjacent pairs of electromagnetic coils in the first set of electromagnetic coils 286. Each of the set of electromagnetic coils 274 has a coil axis 290 oriented perpendicular to the motor shaft 220. Each electromagnetic coil includes one or more conductors that form multiple closed loops centered on the coil axis 290. When current flows through each of the set of electromagnetic coils, each coil generates a magnetic field therein that is oriented substantially parallel to the coil axis.

[0106] When the inner electromagnetic coil 286 and the outer electromagnetic coil 288 are circumferentially overlapped as described above, the magnetic field lines formed by one of the electromagnetic coils pass through one or more closed loops formed by another electromagnetic coil. A portion of the magnetic field formed by one of the inner electromagnetic coils 286 may pass through each of an adjacent pair of outer electromagnetic coils 288. When an angular gap 292 exists between an adjacent pair of outer electromagnetic coils, the magnetic field lines formed by the inner electromagnetic coils may pass through each of the adjacent pair of outer electromagnetic coils 288. It is possible that a portion of the magnetic field generated by the coil does not pass through either of the adjacent pair of outer electromagnetic coils.

[0107] For example, a portion of the magnetic field generated by one of the outer electromagnetic coils 288 may pass through each of an adjacent pair of inner electromagnetic coils 286. If an angular gap 294 exists between an adjacent pair of inner electromagnetic coils, a portion of the magnetic field generated by the outer electromagnetic coil may not pass through either of the adjacent pair of inner electromagnetic coils.

[0108] The motor 212 includes an upper member 296 disposed above the permanent magnets and a set of sensitive pole pieces 272. The upper member covers upper surface areas of the pole pieces and upper surface areas of the permanent magnets. The upper member has a passage 298 that substantially aligns with the passage 276 through the permanent magnets. The upper member 296 may be formed from any suitable material, such as a magnetically sensitive material such as electromagnetic steel.

[0109] The magnetic field generated by the motor enters and exits the upper member axially. Nucleation plate 214 is positioned with a gap between the motor and the nutation plate such that the substantially flat rear surface of the nutation plate is adjacent to upper member 296. The magnetic field lines pass substantially axially through the upper member to exit the motor, cross the motor-nutation plate gap, pass through the nutation plate, cross the nutation plate-motor gap again, and pass substantially axially through the upper member to enter the motor.

[0110] When motor 212 nutates the nutation plate, the nutation teeth of nutation plate 214 engage with the stator teeth of the stator, causing the nutation plate to rotate. The face teeth of nutation plate 214 engage with the output teeth of the output plate, causing the output plate to rotate in the same direction as the nutation plate. In this manner, electromagnetic energy from motor 212 can be converted into rotation of the output plate.

[0111] <How to operate / use> 11 illustrates a method of operation of a self-aligning virtual elliptical drive, generally designated 300. In step 302, method 300 includes providing an input plate having input teeth, providing a nutation plate having nutation teeth and face teeth, and providing a stator gear having stator teeth. The input plate, nutation plate, and stator gear may be manufactured and assembled, for example, as shown in FIG. 1 and described in Example 1. Alternatively, they may be manufactured and assembled in any other suitable manner and configuration consistent with the present disclosure.

[0112] In step 304, method 300 includes rotating the input plate about the axis of rotation. In step 306, method 300 includes engaging the input teeth with the face teeth, thereby rotating the nutation plate. The input teeth and face teeth may be frustoconical surfaces defining two complementary cones, such that engagement between the teeth returns the complementary cones to alignment. In step 308, method 300 includes engaging the nutation teeth with the stator teeth, thereby nutating the nutation plate. The nutation teeth and stator teeth may be wedge-shaped, such that they define two complementary cones, such that engagement between the teeth returns the complementary cones to alignment.

[0113] The input plate can be spaced a predetermined distance from the stator to constrain the nutation plate to the stator gear, thereby maintaining a constant nutation angle and preventing any portion of the nutation plate from exceeding the predetermined distance from the stator gear.

[0114] In some embodiments, the method may include dissipating rotational energy by nutating the nutation plate. This can include stopping the rotation of the force plate and then allowing the input plate to rotate due to inertial energy causing the nutation plate to nutate and rotate.

[0115] In FIG. 12 , a method of operation of a self-centering virtual elliptical drive is generally indicated by the numeral 400. In step 402, method 400 includes providing a motor, e.g., having at least one rounded protrusion on a substantially flat surface and defining an axis of rotation; providing a nutation plate having nutation teeth and surface teeth; providing a stator gear having stator teeth; and providing an output plate having output teeth. The motor, nutation plate, stator gear, and output plate may be manufactured and assembled, for example, as shown in FIGS. 4-8 and described in Example 2. Alternatively, they may be manufactured and assembled in any other suitable manner and configuration consistent with the present disclosure.

[0116] In step 404, the method 400 includes energizing the motor to rotate about the axis of rotation. In step 406, the method 400 includes engaging the motor with the nutation plate. This engagement may include engaging one or more rounded protrusions on the motor with a substantially flat surface on the nutation plate, thereby nutating the nutation plate. In step 408, the method 400 includes engaging the nutation teeth with the stator teeth, thereby rotating the nutation plate. In step 410, the method 400 includes engaging the surface teeth of the nutation plate with the output teeth of the output plate, thereby rotating the output plate.

[0117] The output teeth and face teeth may be provided on frustoconical surfaces that define two complementary cones such that engagement of the teeth returns the complementary cones to alignment. The nut and stator teeth may be wedge-shaped and shaped such that they define two complementary cones such that engagement of the teeth returns the complementary cones to alignment.

[0118] The method may further include stopping rotation of the motor to stop the output plate. The method may further include energizing the motor to rotate in a second rotational direction about the rotation axis, thereby rotating the output plate in the second direction.

[0119] Method 400 can also be utilized to operate a self-centering virtual elliptical drive consistent with the configuration described in Example 3. For example, method 400 can include, in step 402, providing a motor having a permanent magnet and a set of electromagnetic coils defining a central axis; providing a nutation plate formed from a magnetically sensitive material and having nutation teeth and face teeth; providing a stator gear having stator teeth; and providing an output plate having output teeth. The motor, nutation plate, stator gear, and output plate can be manufactured and assembled, for example, as described above for Example 3. Alternatively, they can be manufactured and assembled in any other suitable manner and configuration consistent with the present disclosure.

[0120] When performing method 400 using magnetic forces, method 400 may include, in step 404, energizing the motor to create a magnetic field between the motor and the nutation plate that causes a location of highest magnetic flux density to move. In this case, method 400 may also include, in step 406, magnetizing a magnetically sensitive material of the nutation plate with the motor's magnetic field to engage the motor with the nutation plate, thereby applying a force to the nutation plate. The force is applied to a location of highest magnetic flux density that moves prior to the closest point of movement between the nutation plate and the motor, thereby nutating the nutation plate.

[0121] In step 408, the method 400 engages the nut teeth with the stator teeth, thereby In step 410, method 400 includes engaging the face teeth of the nutation plate with the output teeth of the output plate, thereby rotating the output plate. In some embodiments, the method may further include stopping rotation of the motor to stop the output plate. When performed using magnetic force, the method may further include energizing the motor to move the location of highest magnetic flux density in the opposite direction, thereby rotating the output plate in a second direction.

[0122] Methods of use according to the present disclosure may be employed in combination with any of the previously described embodiments of a self-aligning mechanical drive. Although various steps of methods 300 and 400 have been described and illustrated in Figures 11-12, not all of these steps need be performed, and in some cases, these steps may be performed in a different order than that shown, and in some cases, they may be performed simultaneously.

[0123] Furthermore, the present disclosure encompasses embodiments according to the following notes.

[0124] Clause 1. A nutation plate drive device comprising: a stator gear having a stator axis that is a central axis and a plurality of stator teeth disposed on an inner cylindrical surface; a nutation plate having a nutation axis disposed at a non-zero nutation angle relative to the stator axis, an engagement surface perpendicular to the nutation axis, a plurality of surface teeth on the engagement surface, and a plurality of nutation teeth disposed along an outer periphery of the nutation plate and configured to engage the stator teeth; and an output plate having a plurality of output teeth substantially aligned with the stator axis and configured to engage the surface teeth; wherein at least two sets of the plurality of teeth are configured to engage with one another in a self-aligning manner, whereby the nutation angle is maintained constant as the nutation plate nutates around the periphery of the stator gear.

[0125] Appendix 2. The nutation plate drive device of Appendix 1, wherein at least one of the nutation teeth is wedge-shaped, and a surface of the at least one nutation tooth defines a first line extendable through the center of gravity of the nutation plate; and at least one of the stator teeth is wedge-shaped, and a surface of the at least one stator tooth defines a second line extendable through the center of gravity of the nutation plate.

[0126] Appendix 3. The nutation plate drive device described in Appendix 1, wherein the surface teeth are provided on a truncated cone surface of the nutation plate, and the center of gravity of the nutation plate coincides with the apex of the truncated cone surface of the nutation plate; and the output teeth are provided on a truncated cone surface of the output plate, and the center of gravity of the nutation plate coincides with the apex of the truncated cone surface of the output plate.

[0127] Clause 4. The nutation plate drive apparatus of Clause 1, wherein the nutation plate is constrained so that no portion of the nutation plate exceeds a predetermined distance from the stator gear during nutation.

[0128] Appendix 5. The nutation plate drive device of Appendix 1, wherein the nutation teeth and the face teeth extend in opposite directions parallel to the nutation axis, and the nutation plate is disposed between the stator gear and the output plate.

[0129] Appendix 6. The nutation plate drive device of Appendix 1, wherein the nutation teeth and the surface teeth extend in the same direction parallel to the nutation axis, and the stator gear is disposed between the nutation plate and the output plate.

[0130] Appendix 7. The nutation plate is configured to nutate along the circumference of the stator gear. wherein the nutation plate rotates when the nutation plate nutates around the periphery of the stator gear, and the rotation of the nutation plate rotates the output plate.

[0131] Appendix 8. The nutation plate drive device of Appendix 7, wherein the motor is an electric motor having a substantially flat surface and at least one rounded protrusion extending from the substantially flat surface; the nutation plate has a substantially flat surface opposite the engagement surface; and the at least one rounded protrusion is configured to engage the substantially flat surface of the nutation plate.

[0132] Appendix 9. The rubbing plate drive device of Appendix 7, wherein the motor includes a permanent magnet and a set of electromagnetic coils; the rubbing plate is made of a magnetically sensitive material; and the permanent magnet and the set of electromagnetic coils are configured to cooperate to form a magnetic field between the motor and the rubbing plate along which a position of highest magnetic flux density moves.

[0133] Clause 10. A nutation plate drive apparatus comprising: a stator gear having a central stator axis and a plurality of stator teeth disposed on an inner cylindrical surface; a nutation plate having a nutation axis disposed at a non-zero nutation angle relative to the stator axis, an engagement surface normal to the nutation axis, a plurality of surface teeth on the engagement surface, and a plurality of nutation teeth disposed in a plane normal to both the engagement surface and the nutation axis along an outer periphery of the nutation plate; an output plate having a plurality of output teeth substantially aligned with the stator axis and configured to engage the surface teeth; and means for self-aligning engagement of the stator teeth with the nutation teeth, thereby maintaining the nutation angle constant as the nutation plate nutates around the periphery of the stator gear.

[0134] Appendix 11. The nutation plate drive device of Appendix 10, wherein at least one of the nutation teeth is wedge-shaped, and a surface of the at least one nutation tooth defines a first line extendable through a center of gravity of the nutation plate; and at least one of the stator teeth is wedge-shaped, and a surface of the at least one stator tooth defines a second line extendable through a center of gravity of the nutation plate.

[0135] Appendix 12. The nutation plate drive device of Appendix 10, wherein the surface teeth are provided on a frustum surface of the nutation plate, and the center of gravity of the nutation plate coincides with the apex of the frustum surface of the nutation plate; and the output teeth are provided on a frustum surface of the output plate, and the center of gravity of the nutation plate coincides with the apex of the frustum surface of the output plate.

[0136] Clause 13. The nutation plate drive apparatus of Clause 10, wherein the nutation plate is constrained so that no portion of the nutation plate exceeds a predetermined distance from the stator gear during nutation.

[0137] Appendix 14. The nutation plate drive device of Appendix 10, wherein the nutation teeth and the face teeth extend in opposite directions parallel to the nutation axis, and the nutation plate is disposed between the stator gear and the output plate.

[0138] Appendix 15. The nutation plate drive device of Appendix 10, wherein the nutation teeth and the surface teeth extend in the same direction parallel to the nutation axis, and the stator gear is disposed between the nutation plate and the output plate.

[0139] CLAIM 16. Providing a stator gear, a nutation plate, and an output plate; and connecting a plurality of stator teeth of the stator gear to a plurality of nutation teeth of the nutation plate in a self-aligning manner. engaging a plurality of face teeth of the nutation plate with a plurality of output teeth of the output plate in a self-aligning manner; and nutating the nutation plate around the circumference of the stator gear.

[0140] Clause 17. The method of clause 16, wherein nutating the nutation plate includes: energizing a motor having a substantially flat surface and at least one rounded protrusion extending from the substantially flat surface to rotate the motor about an axis of rotation; and engaging the at least one rounded protrusion with the substantially flat surface of the nutation plate, thereby nutating the nutation plate.

[0141] Clause 18. The method of clause 16, wherein nutating the nutation plate includes energizing a motor having a permanent magnet and a set of electromagnetic coils to create a magnetic field between the motor and the nutation plate that shifts the location of highest magnetic flux density, thereby nutating the nutation plate.

[0142] Clause 19. The method of clause 16, wherein nutating the nutation plate includes rotating the output plate; rotating the output plate with the face teeth engaged with the output teeth rotates the nutation plate; and rotating the nutation plate with the stator teeth engaged with the nutation teeth nutates the nutation plate.

[0143] Clause 20. The method of clause 16, further comprising constraining the nutation plate so that no portion of the nutation plate is more than a predetermined distance from the stator gear during nutation.

[0144] <Effects, features, advantages> The various embodiments of the self-aligning nutation plate drive described herein offer several advantages over known techniques for designing compact, cost-effective nutation plate drives. For example, the exemplary embodiments of the self-aligning nutation plate drive described herein enable a drive without a support shaft or pivot. Of particular note, the exemplary embodiments of the self-aligning nutation plate described herein also reduce vibration, heat from friction, and gear tooth jamming. No known system or device can achieve these features, especially in such a compact size. However, not all embodiments described herein provide the same advantages or the same degree of advantages.

[0145] <Conclusion> The foregoing disclosure may encompass multiple separate inventions with unique utility. While each of these inventions is disclosed in a preferred form, the specific embodiments disclosed and illustrated herein should not be construed in a limiting sense, as many variations are possible. Where section headings are used in this disclosure, such headings are for organizational purposes only and do not constitute a defining feature of the invention sought to be patented. The subject matter of the invention includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions, and / or properties disclosed herein. The following claims particularly set forth certain combinations and subcombinations that are deemed novel and non-obvious. Inventions embodying features, functions, elements, and / or properties in other combinations and subcombinations may also be included in the claims of any application claiming priority from this or a related application. Such claims, whether directed to different inventions, to the same invention, or broader, narrower, equivalent, or different in scope than the original claims, are considered to be within the subject matter of the present disclosure.

Claims

1. a stator gear having a stator shaft as a central shaft and a plurality of stator teeth; a nutation plate having a nutation axis disposed at a non-zero nutation angle relative to the stator axis, a plurality of surface teeth, and a plurality of nutation teeth configured to engage the stator teeth; an output plate substantially aligned with the stator axis and having a plurality of output teeth configured to engage the face teeth, no part of the rubbing plate drive device penetrates a central portion of the rubbing plate; the nutation angle is maintained constant without supporting the nutation plate at a fulcrum as the nutation plate nutates relative to the stator gear. Nucleation plate drive device.

2. The plurality of surface teeth are formed on a truncated cone-shaped surface of the head plate, and the plurality of output teeth are formed on a truncated cone-shaped surface of the output plate, and the plurality of surface teeth and the plurality of output teeth are configured to engage with each other in a self-aligning manner.

2. The pivoting plate drive device according to claim 1.

3. the nutation plate is constrained so that no portion of the nutation plate is more than a predetermined distance from the stator gear during nutation.

2. The pivoting plate drive device according to claim 1.

4. The nutation teeth and the surface teeth extend in opposite directions parallel to the nutation axis, and the nutation plate is disposed between the stator gear and the output plate.

2. The pivoting plate drive device according to claim 1.

5. a motor configured to nutate the nutation plate relative to the stator gear, wherein nutation of the nutation plate around the periphery of the stator gear causes rotation of the nutation plate, and rotation of the nutation plate causes rotation of the output plate.

2. The pivoting plate drive device according to claim 1.