TITLE OF THE INVENTION

MAGNETIC PLANETARY GEAR SYSTEM AND APPARATUS USING THE SAME

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0001] The present invention relates to a planetary gear system and an apparatus using a planetary gear system, and more particularly, to a magnetic planetary gear system and an apparatus using a magnetic planetary gear system. DISCUSSION OF THE RELATED ART

[0002] In general, the durability of mechanical gear systems is dependent upon the mechanical strength of the gears of the power transmission, or speed changing, system. The most common cause of mechanical failure is due to the cumulative fatigue effects resulting from cyclic loading and unloading of gear teeth, whereby, via sliding line contact tooth engagement, large contact stresses are generated. These stresses can break down lubrication films and thereby cause accelerated gear tooth wear and resultant reduction in the operational lifetime of the gearbox. [0003] In addition, precision machining of gear profiles is essential for realizing smooth engagement and disengagement of the gear teeth without chatter and/or backlash. Backlash causes additional transient loading above that of the normal dynamic loads, and also leads to accelerated wear and resultant reduction in gearbox life. This wear leads to significantly increased levels of heat generation, increased noise levels, and related losses in operational efficiency. The rise in heat and noise level generation increase exponentially over time, and, once observed, are strong indications of incipient failure. Excessive heating causes rapid deterioration in the quality of the lubrication fluids via loss of viscosity and exacerbates wear within the gear box, and necessitates periodic maintenance to assure that both lubricant quality, filtration of contaminants, and fill levels are maintained.

[0004] Finally, gear teeth provide "hard-coupling" from the input shaft to the output shaft, and shaft-line torsional vibrations, either from the drive input shaft or the load output shaft are directly coupled to one another. Transient shock loads may also be generated that can cause catastrophic gear tooth failure.

[0005) A need exists to replace gear teeth with a non-mechanical alternative, one that is more tolerant of minor dimensional variation in tooth profile and tooth spacing interval. This alternative would not be susceptible to high dynamic and transient stresses exhibited by the related art, would provide means to operate at greatly reduced stress levels, and would be capable of eliminating sliding line contact between gear teeth without the need for any lubrication, such that a highly efficient transfer of torque and speed is thereby accomplished.

[0006] This non-mechanical alternative would provide "soft-coupling" between the respective tooth features, such that both vibration isolation and dampening could be realized, and, due to the lack of any mechanical contact between respective tooth engagement, would result in the elimination of the need for lubrication, greatly reduce heat generation, and also achieve greatly reduced noise levels.

SUMMARY OF THE INVENTION

[0007] Accordingly, the invention is directed to a magnetic gear system and an apparatus using a magnetic gear system that substantially obviate one or more of the problems due to limitations and disadvantages of the related art. [0008] Particular embodiments of the invention provide a magnetic gear system for transferring rotational motion and torque in a manner that reduces or prevents generation of friction and heat.

[0009] Particular embodiments of the invention provide a magnetic gear system for transferring rotational motion and torque in a manner that reduces generation of noise. [0010] Particular embodiments of the invention provide a magnetic gear system for transferring rotational motion and torque in a manner that reduces weight of the system. [0011] Particular embodiments of the invention provide a magnetic gear system for transferring rotational motion and torque in a manner that reduces or eliminates the need for lubrication.

[0012] Particular embodiments of the invention provide the elimination of all or substantially all gear backlash.

[0013] Particular embodiments of the invention provide the elimination of all or substantially all gear chatter. [0014] Particular embodiments of the invention provide the function of a slip clutch.

[0015] Particular embodiments of the invention provide the benefits of vibration isolation and dampening.

[0016] Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. The above and other advantages of the invention will be realized and attained by the exemplary structure particularly pointed out in the written description hereof as well as the appended drawings.

[0017] Particular embodiments of the invention provide a planetary gear system that has a ring gear having an inner circumference; a planet gear having an outer circumference; and a sun gear having an outer circumference. One of the ring gear, the planet gear or the sun gear is a driving gear and one of the ring gear, the planet gear or the sun gear is a driven gear, and rotation of the driven gear is caused by magnetic forces between the driving gear and the driven gear.

[0018] Other embodiments of the invention provide a method of transferring rotational motion using a planetary gear system having a ring gear having an inner circumference, a planet gear having an outer circumference, and a sun gear having an outer circumference. The method includes rotating a first one of the ring gear, the planet gear or the sun gear by a rotational force outside the gear system; and magnetically coupling the first one of the ring gear, the planet gear or the sun gear to a second one of the ring gear, the planet gear or the sun gear. The rotation of the first one of the ring gear, the planet gear or the sun gear causes the second one of the ring gear, the planet gear or the sun gear to rotate.

[0019] Other embodiments of the invention provide a vehicle transmission for use in a vehicle. The transmission has a planetary gear system that has a ring gear having an inner circumference; a planet gear having an outer circumference; and a sun gear having an outer circumference. One of the ring gear, the planet gear or the sun gear is a driving gear and one of the ring gear, the planet gear or the sun gear is a driven gear, and rotation of the driven gear is caused by magnetic forces between the driving gear and the driven gear. The transmission also has a shaft for attaching the driven gear to a drive shaft of the vehicle.

[0020] Other embodiments of the invention provide a vehicle that has transmission. The transmission has a planetary gear system that has a ring gear having an inner

circumference; a planet gear having an outer circumference; and a sun gear having an outer circumference. One of the ring gear, the planet gear or the sun gear is a driving gear and one of the ring gear, the planet gear or the sun gear is a driven gear, and rotation of the driven gear is caused by magnetic forces between the driving gear and the driven gear. The transmission also has a shaft for attaching the driven gear to a drive shaft of the vehicle. The vehicle also has a drive shaft; a drive motor attached to the driving gear; and a motion transfer system attached to the drive shaft. The motion transfer system is for transmitting the rotation of the drive shaft to a propulsion force for propelling the vehicle.

[0021] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention without limiting the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a front view of an exemplary planetary gear system according to the invention;

[0023] FIG. 2 is a rear view of the exemplary planetary gear system of FIG. 1 according to the invention;

[0024] FIG. 3 is a cross-sectional view along IH-III of FIGs. 1 and 2 according to the invention;

[0025] FIG. 4 is a plan view of an exemplary ring gear of the planetary gear system of FIG. 1 according to the invention;

[0026] FIGs. 5 A and 5B are cross-sectional and plan views of an exemplary planet gear of the planetary gear system of FIG. 1 according to the invention; [0027] FIGs. 6A and 6B are cross-sectional and plan views of an exemplary sun gear of the planetary gear system of FIG. 1 according to the invention;

[0028] FIGs. 7A and 7B are cross-sectional and plan views of an exemplary planet gear carrier according to the invention;

[0029] FIGs. 8A and 8B are cross-sectional and plan views of an exemplary planet gear retainer according to the invention;

[0030] FIG. 9 is a cross-sectional view of an exemplary planet gear shaft according to the invention;

[0031) FIG. 10 is a cross-sectional view of another exemplary planetary gear system according to the invention;

[0032] FIG. 1 1 is a cross-sectional view of the coupling shaft of FIG. 10 according to the invention;

[0033] FIG. 12 is a cross-sectional view of another exemplary planetary gear system according to the invention.

[0034] FIG. 13 is a plan view of another exemplary planetary gear system according to the invention;

[0035] FIGs. 14A and 14B are schematic and cross-sectional views of an exemplary mode of operation for a planetary gear system according to the invention;

[0036] FIGs. 15A and 15B are schematic and cross-sectional views of another exemplary mode of operation for a planetary gear system according to the invention;

[0037] FIGs. 16A and 16B are schematic and cross-sectional views of another exemplary mode of operation for a planetary gear system according to the invention;

[0038] FIG. 17 is a schematic diagram showing the magnetic interactions between magnets of ring and planet gears at a first time period according to the invention;

[0039] FIG. 18 is a schematic diagram showing the magnetic interactions between magnets of ring and planet gears at a second time period according to the invention;

[0040] FIG. 19 is a schematic diagram showing the magnetic interactions between magnets of ring and planet gears at a third time period according to the invention;

[0041] FIG. 20 is a schematic diagram showing the magnetic interactions between magnets of sun and planet gears at a first time period according to the invention;

[0042] FIG. 21 is a schematic diagram showing the magnetic interactions between magnets of sun and planet gears at a second time period according to the invention;

[0043] FIG. 22 is a schematic diagram showing the magnetic interactions between magnets of sun and planet gears at a third time period according to the invention;

[0044] FIG. 23 is an enlarged view of a first interface between ring and planet gears according to the invention;

[0045] FIG. 24 is an enlarged view of a second interface between planet and sun gears according to the invention;

[0046] FIG. 25 is an enlarged view of a third interface between ring and planet gears according to the invention;

[0047 J FIG. 26 is an enlarged view of a fourth interface between planet and sun gears according to the invention;

(0048] FIG. 27 is a cross sectional view of an exemplary housing for a planetary gear system according to the invention;

[0049] FIG. 28 is a schematic diagram of an exemplary transmission in accordance with the invention; and

[0050] FIG. 29 is a schematic diagram of an exemplary vehicle in accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION [0051] Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. [0052] FIGs. 1 and 2 are front and rear views of an exemplary planetary gear system according to the invention. In FIGs. 1 and 2, a gear system 10 includes a ring gear body 12, a plurality of assembly holes 14, a plurality of planet gears 200, and a sun gear 300. Although this example has five planet gears 200, a single planet gear or any other number of planet gears may be used. Regardless of the number of planet gears used, it is preferred that the planetary system be balanced to avoid rotational vibration. This balancing may be achieved by symmetric placement of planet gears and/or the use of other balancing structures or voids. As shown in FIG. 1, the ring gear body 12 includes a plurality of ring gear magnets 120 disposed along an inner surface thereof. Each of the ring gear magnets 120 may have a trapezoidal shape such that the smaller side may be disposed to face toward a center portion of the ring gear body 12. The smaller sides of each of the ring gear magnets 120 may have only North magnetic polar orientations. In addition, each of the magnets 120 may have other geometries so long as the North magnetic polar orientations face inward. Throughout this example, the North magnetic polar orientations of one set of magnets face the North magnetic polar orientations of opposing magnets on other gears. It is noted that other examples of the invention orient the magnets so that the South magnetic polar orientations of one set of magnets face the South magnetic polar orientations of opposing magnets on other gears. [0053] In FIGs. 1 and 2, each of the planet gears 200 is disposed about the sun gear 300, and each includes a plurality of planet gear magnets 225. Each of the planet gear magnets 225 may have a trapezoidal shape such that the smaller side may be disposed

to face away from a planet gear rotational shaft 210 and toward the smaller sides of the ring gear magnets 120. The smaller sides of each of the planet gear magnets 225 may have North magnetic polar orientations facing outward. The magnetic polar orientations of the planet gear magnets 225 are preferably similar to the magnetic polar orientations of the ring gear magnets 120. Thus, repulsive forces are generated between the planet gear magnets 225 and the ring gear magnets 120. In addition, each of the magnets 225 and 120 may have other geometries so long as the North magnet polar orientations face outward.

[0054] In FIGs. 1 and 2, each of the planet gears 200 is separated from the sun gear 300 and the ring gear body 12 by a gap within a range of, for example, about 0.005 inches to about 0.010 inches. Accordingly, none of the planet gears 200, the sun gear 300, and the ring gear body 12 contacts any other.

[0055] FIG. 3 is a cross-sectional view along III-III of FIGs. 1 and 2 according to the invention. In FIG. 3, each of the planet gears 200 is formed to simultaneously rotate about its planet gear rotational shafts 210. In addition, each of the planet gears 200 is coupled to a planet gear carrier plate 220 via a fastener,270b, and each of the planet gears 200 is coupled to a planet gear retainer plate 230 via a fastener 270a. Moreover, each of the planet gears 200 is coupled to the planet gear rotational shafts 210 using a pair of bearings 212a and 212b. Specifically, inner surfaces of the bearings 212a and 212b are disposed on exterior end portions of the planet gear rotational shaft 210, and outer surfaces of the bearings 212a and 212b are disposed within inner surfaces of the planet gears 200. For example, the bearings 212a and 212b may be ceramic bearings. [0056] In FIGs. 1 and 2, the sun gear 300 include a plurality of sun gear magnets 325 that may have trapezoidal shapes such that the smaller sides may be disposed to face away from sun gear rotational shaft 600 and toward the smaller sides of the planet gear magnets 225. The smaller sides of the sun gear magnets 325 each have North magnetic polar orientations. The magnetic polar orientations of the sun gear magnets 325 are preferably similar to the magnetic polar orientations of the planet gear magnets 225. Thus, repulsive forces may be generated between the sun gear magnets 325 and the planet gear magnets 225. In addition, each of the sun gear magnets 325 may have other geometries so long at the North magnet polar orientations face outward.

[0057] In FIG. 3, the sun gear 300 is coupled to the rotational shaft 600 using a fastener 610, a retainer 620, and a key 630 inserted into an end portion of the rotational shaft 600 and the sun gear 300. Similarly, the planet gear retainer plate 220 is coupled to the rotational shaft 500 using a fastener 510, a retainer 520, and a key 530 inserted into an end portion of the rotational shaft 500 and the planet gear retainer plate 220. [0058) FIG. 4 is a plan view of an exemplary ring gear of the planetary gear system of FIG. 1 according to the present invention. In FIG. 4, the ring gear 100 includes a ring gear body 1 10 and a plurality of assembly holes 130 disposed at four corner regions of the ring gear body 1 10. The ring gear body 1 10 includes a plurality of ring gear magnet grooves disposed along an inner surface. Each of the grooves includes tapered sidewalls 122a and a bottom 122b. The tapered sidewalls 122a have a major width Wmaj at a depth D from the inner surface of the ring gear body 1 10 and a minor width Wmin along the inner surface of the ring gear body 1 10. Here, the ring gear body 1 10 has a minor diameter Dmin at the inner surface of the ring gear body 1 10, and a major diameter Dmaj extending from opposing bottoms 122b that extend to the depth D. In addition, each of the grooves may be angularly offset from each other by an offset angle θl . For example, in FIG. 4, twenty grooves are shown at the offset angle 01 , which may be about 18 degrees. Alternatively, the total number of grooves may be varied depending upon the geometry and size of the magnets that are to be placed into the grooves of the ring gear body 1 10. This would change the offset angle 01. Although even spacing is shown in this example, other spacing can be used. [0059] FIGs. 5 A and 5B are cross-sectional and plan views of an exemplary planet gear of the planetary gear system of FIGs. 1-3 according to the invention. In FIGs. 5 A and 5B, a planet gear 200 may include a planet gear body 215 having a plurality of grooves 2001 , a through hole 230 and concentric recesses 240 and 250. In addition, the plurality of grooves 2001 are disposed along a circumference of the planet gear body 215 to extend into the planet gear body 215 to a depth Dmaj . Here, the planet gear body 215 includes a major outer diameter DPLANmaj and a minimum diameter DPLANmin. Each of the grooves 2001 may have a major width Wmaj at the depth Dmaj and a minor width Wmin at the circumferential surface of the planet gear body 215. Each of the grooves 2001 may receive a magnet 225. Although not explicitly shown, each of the grooves 2001 may be mutually offset by an angle of about 72

degrees. Alternatively, the total number and size of grooves 2001 and magnets 225 may be varied depending upon the geometry and size of the magnets that are to be placed into the grooves 2001 of the planet gear body 215.

[0060] In FIG. 5B, the planet gear body 215 includes the through hole 230 having a diameter DlPLAN, recesses 240 each having a diameter D2PLAN, and recesses 250 each having a diameter D3PLAN. As shown in FIG. 3, the through hole 230 accommodates the planet gear rotational shaft 210, the recesses 250 accommodate the bearings 212a and 212b, and the recesses 240 are unfilled spaces between the sidewall of the planet gear body 215 and the bearings 212a and 212b. [0061] FIGs. 6A and 6B are cross-sectional and plan views of a sun gear of the planetary gear system of FIGs. 1 -3 according to the invention. In FIGs. 6A and 6B, a sun gear 300 may include a sun gear body 310 having a plurality of grooves 320, a recess 330 having a diameter D2SUN and a through hole 340 having a diameter Dl SUN. In addition, the plurality of grooves 320 are disposed along a circumference of the sun gear body 310 to extend into the sun gear body 310 to a depth Dmaj. Here, the sun gear body 310 includes a major outer diameter DSUNmaj and a minimum diameter DSUNmin. Each of the grooves 320 may have a major width Wmaj at the depth Dmaj and a minor width Wmin at the circumferential surface of the sun gear body 310. Each of the grooves 320 may receive a magnet. Although not explicitly shown, each of the grooves 320 in this example are offset by an angle of about 36 degrees. Alternatively, the total number and size of grooves 320 and magnets may be varied depending upon the geometry and size of the magnets that are to be placed into the grooves 320 of the sun gear body 310.

[0062] FIGs. 7A and 7B are cross-sectional and plan views of an exemplary planet gear carrier plate according to the invention. In FIGs. 7A and 7B, the planet gear carrier plate 220 includes a body portion 221 having a first outer diameter D4PCAR and a stepped portion 222 having a second outer diameter D2PCAR. As shown, the first outer diameter D4PCAR has a first thickness WlPCAR and the second outer diameter D2PCAR has a second thickness W2PCAR that is greater than the first thickness WlPCAR. In addition, the second outer diameter D2PCAR includes a through hole 224 having a diameter DlPCAR and a keyway 226. Thus, as shown in FIG. 3, the rotational shaft 500 is coupled to the planetary gear carrier plate 220 using the fastener

510, the retainer 520, and the key 530 inserted into the keyway 226 of the planet gear carrier plate 220 and the end portion of the rotational shaft 500. [0063] In FIG. 7B, the body portion 221 includes a plurality of through holes 223 that are equally spaced apart along a third diameter D3PCAR of the planet gear carrier plate 220. Each of the plurality of through holes 223 includes a straight bore portion 223a and a counter-sink portion 223b. Accordingly, when fasteners, such as the fastener 270b (in FIG. 3), for example, are inserted into the through holes 223, the threaded region of the fasteners extend through the straight bore portion 223a and into the planet gear rotational shafts 210, and the head region of the fasteners are retained within the counter-sink portion 223b.

[0064] FIGs. 8A and 8B are cross-sectional and plan views of an exemplary planet gear retainer according to the invention. In FIGs. 8A and 8B, the planet gear retainer plate 230 includes a body portion 231 having a first outer diameter D3PRET and an opening 232 having a second inner diameter DlPRET. In addition, the body portion 231 includes through holes 233 distributed along a diameter D2PRET. Each of the through holes 233 includes a straight bore portion 233a and a counter-sink portion 233b. Accordingly, when fasteners, such as the fastener 270a (in FIG. 3), for example, are inserted into the through holes 233, the threaded regions of the fasteners extend through the straight bore portion 233a and into the planet gear rotational shafts 210, and the head region of the fasteners are retained within the counter-sink portion 233b. As shown in FIG. 3, the rotational shaft 600 extends through the opening 232. [0065] FIG. 9 is a cross-sectional view of an exemplary planet gear shaft according to the invention. In FIG. 9, a planet gear shaft 210 having a length Ll includes a central body portion 230a having a diameter D3 and a length L2, and first and second lateral body portions 230b and 230c each having diameters D2 and lengths L3. The first lateral body portion 230b includes a retainer ring groove 232a disposed adjacent to a chamfered edge 242a of the end region 240a. In addition, the end region 240a includes a threaded hole 250a having a diameter Dl extending through the first lateral body portion 230b into the central body portion 230a by a length L4. Similarly, the second lateral body portion 230c includes a retainer ring groove 232b disposed adjacent to a chamfered edge 242b of the end region 240b. In addition, the end region 240b includes

a threaded hole 250b having a diameter Dl extending through the second lateral body portion 230c into the central body portion 230a by a length IA. [0066] FIG. 10 is a plan view of another exemplary planetary gear system according to the invention. In FIG. 10, two of the exemplary planetary gear systems of FIGs. 1 -3 may be coupled together in order to provide a system 20 having an increased or decreased input/output ratio. As shown, a first planetary gear system 30 may be coupled to a second planetary gear system 40 using a coupling member 50. For example, the coupling member 50 may resemble the ring gear body 1 10 (in FIG. 4), or may simply comprise spacers aligned with and between the plurality of assembly holes 14 (in FIGs. 1 and 2). In this case, fasteners may be inserted through the plurality of assembly holes 14 (in FIGs. 1 and 2) and the coupling member 50. Alternatively, a single part may provide the functions of the ring gear bodies of both planetary gear systems 30 and 40 and coupling member 50.

[0067] In FIG. 10, a coupling shaft 700 may be coupled to the planet gear carrier 30a of the first planetary gear system 30 and the through hole 340 (in FIGs. 6A and 6B) of the sun gear 300 of the second planetary gear system 40. Accordingly, the second outer diameter D2PCAR (in FIGs. 7A and 7B) of the planet gear carrier 30a is less than the second inner diameter DlPRET (in FIGs. 8 A and 8B) of the planet gear retainer 40b. Thus, spacing between the first and second planetary gear systems 30 and 40 may be reduced.

[0068] In FIG. 10, the coupling shaft 700 is connected to the planet gear carrier 30a of the first planetary gear system 30 via a key 714a inserted into a groove of the coupling shaft 700 and the keyway 226 (in FIG. 7B) of the planet gear carrier 30a, and by a fastener 710a and a retainer 712a connected to a first end region of the coupling shaft 700. Similarly, the coupling shaft 700 is connected to the through hole 340 (in FIGs. 6 A and 6B) of the sun gear 300 of the second planetary gear system 40 via a key 714b inserted into a groove of the coupling shaft 700 and the keyway 632 (in FIG. 6B) of the sun gear 300, and by a fastener 710b and a retainer 712b connected to a second end region of the coupling shaft 700.

[0069] FIG. 1 1 is a cross-sectional view of the coupling shaft of FIG. 10 according to the invention. In FIG. 1 1 , the coupling shaft 700 may have a length Lc and a diameter Dc. Accordingly, the length Lc will determine the spacing between the first and second

planetary gear systems 30 and 40, and the diameter Dc may be equal to the diameter DlPCAR of the through hole 224 of the planet gear carrier plate 220 (in FIGs. 7 A and 7B) and the diameter Dl SUN of the through hole 340 of the sun gear 300 (in FIGs. 6A and 6B).

[0070) In FIG. 1 1 , the coupling shaft 700 includes a retainer ring groove 714 and threaded holes 712 extending into the coupling shaft 700. Here, a retainer ring (not shown) may be disposed within the retainer ring groove 714 to separate the planet gear carrier 30a of the first planetary gear system 30 from the sun gear 300 of the second planetary gear system 40. Similarly, each of the rotational shafts 500 and 600 may include retainer ring grooves to receive retainer rings. In addition, the fasteners 710a and 710b couple the coupling shaft 700 between the planet gear carrier 30a of the first planetary gear system 30 and the sun gear 300 of the second planetary gear system 40.

[0071) FIG. 12 is a plan view of another exemplary planetary gear system according to the invention. In FIG. 12, two of the exemplary planetary gear systems of FIGs. 1-3 are coupled together in order to provide a system 20' having an increased or decreased input/output ratio. However, as shown in FIG. 12, use of a coupling shaft 700, as well as the associated hardware, is unnecessary. Specifically, the planet gear carrier 30a of the first planetary gear system 30' may include a first portion 30al that functions as the sun gear of the second planetary gear system 40', and may include a second portion 30a2 that functions as the planet gear carrier 30a of FIG. 10. Accordingly, by providing a single planetary gear carrier 30a having both first and second portions 30al and 30a2, a distance between the first and second planetary gear systems 30' and 40' may be reduced, and overall weight of the exemplary planetary gear system of FIG. 12 may be reduced.

[0072] According to the invention, as exemplarily shown in FIG. 10 and 12, if the rotational shaft 600 is to be an input shaft and the rotational shaft 500 is to be an output shaft, then the input/output ratio of the exemplary planetary gear system of FIG. 10 would be about 9: 1. Specifically, for every nine full rotations of the input shaft 600, the output shaft 500 would rotate one full rotation. Conversely, if the rotational shaft 500 is to be an input shaft and the rotational shaft 600 is to be an output shaft, then for every full rotation of the input shaft 500, the output shaft 600 would rotate nine full rotations. Of course, additional individual planetary gear systems may be added to the

first and second planetary gear systems 30 and 40 to further increase or decrease the input/output ratio(s). In addition, by changing the relative sizes of the various gears, other gear ratios can be provided.

[0073] FIG. 13 is a plan view of another exemplary planetary gear system according to the invention. In FIG. 13, a planetary gear system 10 may include the fundamental elements of FIGs. 1-3, but the ring gear 12c may have a circular geometry. Moreover, although not specifically shown, the planetary gear system 10 may include the multiple configurations of FIGs. 10 and 12, such that a plurality of the individual planetary gear systems of FIG. 13 may be provided.

[0074] According to the invention, any one of the ring gear body, planet carrier, and sun gear body may be held stationary (i.e., locked). Accordingly, the other two of the ring, planet, and sun gears are rotatable, thereby providing selectable input/output ratio(s). Moreover, each of the ring, planet, and sun gears may all rotate without any single one of the ring, planet, and sun gears being locked.

[0075] FIGs. 14A and 14B are schematic and sectional views of an exemplary mode of operation for the planetary gear system according to the present invention. In FIGs. 14A and 14B, the sun gear 300 may remain stationary (ω4=0), whereas each of the planet gears 200 may rotate about their respective axes 210 (ω3>0) and each of the planet gears 200 may revolve about the sun gear 300 via the planet carrier and retainer plates 220 and 230 (ω2>0), as shown in FIG. 14B. In addition, the ring gear 12c may revolve about the sun gear 300 (ωl>0). Accordingly, the ring gear 12c may be coupled to a rotational shaft 800, such that a rotational shaft 500 coupled to the planet gear retainer plate 220 attached to each of the planet gears 200 may be used as an input or output of the exemplary planetary gear system and the rotational shaft 800 coupled to the ring gear 12c may be used as an output or input of the exemplary planetary gear system.

[0076] In FIG. 14B, the ring gear 12c may be coupled to the rotational shaft 800 using an assembly 12cl and fasteners 12c2. Specifically, the ring gear 12c may extend circumferentially and be symmetrically connected to the assembly 12cl using the fasteners 12c2. With this configuration, the spider assembly 12cl may have a circular geometry commensurate with the geometry of the ring gear 12c.

[0077] As shown in FIG. 14B, the rotational shaft 800 may be coupled to a central region of the assembly 12cl . In addition, the sun gear 300 may extend through the opening of the planet gear retainer plate 230 to provide stability and strength to the planetary gear system. However, the sun gear 300 may be provided to not extend through the opening of the planet gear retainer plate 230 if overall size of the planetary gear system is to be made a smaller.

[0078] FIGs. 15A and 15B are schematic and cross-sectional views of another exemplary mode of operation for the planetary gear system according to the invention. In FIGs. 15A and 15B, the planet gear carrier and retainer plates 220 and 230 may remain stationary (ω2=0), whereas the sun gear 300 and ring gear 12c may rotate. In addition, although the planet gear carrier and retainer plates 220 and 230 may remain stationary, each of the planet gears 200 may rotate (ω3>0) about their individual axes 210. Since the planet gear carrier and retainer plates 220 and 230 may remain stationary, the thickness of the planet gear carrier and/or retainer plates 220 and 230 may be larger than the thicknesses of the planet gear carrier and retainer plates 220 and 230 shown in FIGs. 14A and 14B.

(0079] Accordingly, the sun gear 300 may rotate (ω4>0) and the ring gear 12c may rotate (ωl>0). Thus, the ring gear 12c may be coupled to a rotational shaft 800, such that a rotational shaft 600 coupled to the sun gear 300 may be used as an input or output of the exemplary planetary gear system and the rotational shaft 800 coupled to the ring gear 12c may be used as an output or input of the exemplary planetary gear system. [0080] In FIG. 15B, the ring gear 12c may be coupled to the rotational shaft 800 using an assembly 12cl and fasteners 12c2. With this configuration, the assembly 12cl may have a geometry, for example circular, commensurate with the geometry of the ring gear 12c.

[0081] As shown in FIG. 15B, the rotational shaft 800 may be coupled to a central region of the assembly 12cl . The rotational shaft 600 may be coupled to the sun gear 300 using, for example, the fastener/retainer/key combination as shown in FIG. 3. [0082] FIGs. 16A and 16B are schematic and cross-sectional views of another exemplary mode of operation for the planetary gear system according to the present invention. In FIGs. 16A and 16B, the ring gear 12c may remain stationary (ωl=0), whereas the planet gears 200 may rotate (ω3>0), the planet gear carrier and retainer

plates 220 and 230 may rotate (ω2>0), and the sun gear 300 may rotate (ω4>0). A rotational shaft 500 coupled to the planet gear carrier plate 220 may be used as an input or output of the exemplary planetary gear system and the rotational shaft 600 coupled to the sun gear 300 may be used as an output or input of the exemplary planetary gear system.

[0083] In FIG. 16B, the rotational shaft 600 may be coupled to the sun gear 300 using the fastener/retainer/key combination as shown in FIG. 3, for example. Similarly, the rotational shaft 500 may be coupled to the planet gear carrier plate 220 using the fastener/retainer/key combination as shown in FIG. 3, for example. [0084) FIG. 17 is a schematic diagram showing the magnetic interactions between magnets of ring and planet gears at a first time period according to an example of the invention. In FIG. 17, the magnets 225(1) and 225(2) of the planet gear 200 are disposed on opposite sides of the magnet 120(1) of the ring gear 12. Accordingly, the repulsive magnetic forces Rl and R2 between the North face of the magnet 120(1) and North faces of the magnets 225(1) and 225(2) are relatively equal. [0085] FIG. 18 is a schematic diagram showing the magnetic interactions between magnets of ring and planet gears at a second time period according to an example of the invention. In FIG. 18, as the planet gear 200 rotates at a second time period after the first time period, the planet gear 200 rotates about its center 210 with an angular velocity ω3 and revolves about the sun gear (not shown) with a rotational velocity ω2. Accordingly, an attractive magnetic force A3 is established between the North face of ^' the magnet 225(2) and the South face of the magnet 120(2), and another attractive magnetic force A4 is established between the South face of the magnet 225(2) and the North face of the magnet 120(2). In addition, a repulsive magnetic force R3 is established between the North face of the magnet 120(2) and the North face of the magnet 225(2).

[0086] FIG. 19 is a schematic diagram showing the magnetic interactions between magnets of ring and planet gears at a third time period according to an example of the invention. In FIG. 19, as the planet gear 200 rotates at a third time period after the second time period, the planet gear 200 rotates about its center 210 with an angular velocity ω3 and revolves about the sun gear (not shown) with a rotational velocity ω2. Accordingly, an attractive magnetic force A3 is established between the South faces of

the magnets 120(1) and 120(2) and the North face of the magnet 225(2), and an attractive force A4 is established between the South face of the magnet 225(2) and the North faces of the magnets 120(1) and 120(2). In addition, a repulsive magnetic force R3 is established between the North face of the magnet 225(2) and the North face of the magnet 120(2).

[0087) FIG. 20 is a schematic diagram showing the magnetic interactions between magnets of sun and planet gears at a first time period according to an example of the invention. In FIG. 20, the magnets 225(1) and 225(2) of the planet gear 200 are disposed on opposite sides of the magnet 325(1) of the sun gear 300. Accordingly, the repulsive magnetic forces Rl and R2 between the North face of the magnet 325(1) and North faces of the magnets 225(1) and 225(2) are relatively equal. In addition, the attractive forces Al are established between the North face of the magnet 325(1) and the South faces of the magnets 225(1) and 225(2), and the attractive forces A2 are established between the South face of the magnet 325(1) and the North faces of the magnets 225(1) and 225(2).

[0088] FIG. 21 is a schematic diagram showing the magnetic interactions between magnets of sun and planet gears at a second time period according to an example of the invention. In FIG. 21, as the planet gear 200 rotates at a second time period after the first time period, the planet gear 200 rotates about its center 210 with an angular velocity ω3 and revolves about the sun gear (not shown) with a rotational velocity ω2. Accordingly, an attractive magnetic force A2 is established between the North face of the magnet 225(1) and the South face of the magnet 325(2), and a repulsive magnetic force R3 is established between the North face of the magnet 225(1) and the North face of the magnet 325(2). Concurrently, the repulsive magnetic force Rl decreases, as well as the attractive forces A 1.

[0089] FIG. 22 is a schematic diagram showing the magnetic interactions between magnets of sun and planet gears at a third time period according to an example of the invention. In FIG. 22, the magnets 325(1) and 325(2) of the sun gear 300 are disposed on opposite sides of the magnet 225(1) of the planet gear 200. Accordingly, the repulsive magnetic forces R2 and R3 between the North face of the magnet 225(1) and North faces of the magnets 325(1) and 325(2) are relatively equal. In addition, the attractive forces Al are established between the South face of the magnet 225(1) and

the North faces of the magnets 325(1) and 325(2), and the attractive forces A2 are , established between the North face of the magnet 225(1) and the South faces of the magnets 325(1) and 325(2).

[0090] As shown in FIGs. 17-22, multiple magnetic interactions takes place between the planet gears and the ring and sun gears. For example, the planet gears undergo net repulsive and net attractive modes of operation due to the North-North repulsive magnetic interactions between facing portions of the respective magnets and North- South attractive magnetic interactions between other portions of the respective magnets. However, the predominate magnetic interaction of the planetary gear system may be considered repulsive since it is the North-North repulsive magnetic interactions that are stronger than the North-South attractive magnetic interactions during operation of the system.

[0091] FIG. 23 is an enlarged view of a first interface between ring and planet gears according to an example of the invention. In FIG. 23, the ring gear 12 and the planet gear 200 may be separated by a first gap Gl , which may, for example, be within a range of about 0.010 inches to about 0.100 inches. The ring gear 12 may include the plurality of the magnets 120 having, for example, a trapezoidal shape. The magnet 120 in this example includes tapered sides 120sl and 120s2, a minor face 120minor, and an opposing major surface 120major. Here, the minor face 120minor has the North magnetic polar orientation and the major face 120major has the South magnetic polar orientation. In addition, the minor face 120minor is disposed within the corresponding groove disposed along the inner circumference 12ic of the ring gear 12. The minor face 120minor may protrude slightly from, be flush with, or be slightly recessed from the inner circumference 12ic of the ring gear 12.

[0092] In FIG. 23, the planet gear 200 may include the plurality of the magnets 225 having, for example, a trapezoidal shape. The magnet 225 includes tapered sides 225s 1 and 225s2, a minor face 225minor, and an opposing major surface 225major. Here, the minor face 225minor has the North magnetic polar orientation and the major face 225major has the South magnetic polar orientation. In addition, the minor face ?25minor is disposed within the corresponding groove disposed along the outer circumference 215oc of the planet gear body 215. Thus, the minor face 225minor may

protrude slightly from, be flush with, or be slightly recessed from the outer circumference 215oc of the planet gear body 215.

[0093] FIG. 24 is an enlarged view of a second interface between planet and sun gears according to an example of the invention. In FIG. 24, the planet gear 200 and the sun gear 300 may be separated by a second gap G2, which, for example, may be within a range of about 0.010 inches to about 0.100 inches. The planet gear 200 may include the plurality of magnets 225 having, for example, a trapezoidal shape. The magnet 225 in this example includes tapered sides 225s 1 and 225s2, a minor face 225minor, and an opposing major surface 225major. Here, the minor face 225minor has the North magnetic polar orientation and the major face 225major has the South magnetic polar orientation. In addition, the minor face 225minor is disposed within the corresponding groove disposed along the inner circumference 215oc of the planet gear body 215. Thus, the minor face 225minor may protrude slightly from, be flush with, or be slightly recessed from the outer circumference 215oc of the planet gear body 215. [0094] In FIG. 24, the sun gear 300 may include the plurality of the magnets 325 having, for example, a trapezoidal shape. The magnet 325 includes tapered sides 325s 1 and 325s2, a minor face 325minor, and an opposing major surface 325major. Here, the minor face 325minor has the North magnetic polar orientation and the major face 325major has the South magnetic polar orientation. In addition, the minor face 325minor is disposed within the corresponding groove disposed along the outer circumference 310oc of the sun gear body 310. Thus, the minor face 325minor may protrude slightly from, be flush with, or be slightly recessed from the outer circumference 310oc of the sun gear body 310.

[0095] FIG. 25 is an enlarged view of a third interface between ring and planet gears according to an example of the invention. In FIG. 25, the ring gear 12 and the planet gear 200 may be separated by a third gap G3, which, for example, may be within a range of about 0.010 inches to about 0.100 inches. The ring gear 12 may include the plurality of the magnets 120 having, for example, a trapezoidal shape. The magnet 120 in this example includes tapered sides 120sl and 120s2, a minor face 120minor, and an opposing major surface 120major. Here, the minor face 120minor has the North magnetic polar orientation and the major face 120major has the South magnetic polar orientation. In addition, the minor face 120minor is disposed within the corresponding

groove disposed along the inner circumference 12ic of the ring gear 12. Here, the minor face 120minor may have a curved surface about equal to the curvature of the inner circumference 12ic of the ring gear 12. In addition, the curved minor face 120minor may be flush with the inner circumference 12ic of the ring gear 12, extend past the inner circumference 12ic of the ring gear 12 by a distance less than the third gap G3, or be recessed below the inner circumference 12ic of the ring gear 12. [0096] In FIG. 25, the planet gear 200 may include the plurality of the magnets 225 having, for example, a trapezoidal shape. The magnet 225 includes tapered sides 225s 1 and 225s2, a minor face 225minor, and an opposing major surface 225major. Here, the minor face 225minor has the North magnetic polar orientation and the major face 225major has the South magnetic polar orientation. In addition, the minor face 225minor is disposed within the corresponding groove disposed along the outer circumference 215oc of the planet gear body 215. Here, the minor face 225minor may have a curved surface about equal to the curvature of the outer circumference 215oc of the planet gear body 215. In addition, the curved minor face 225minor may be flush with the outer circumference 215oc of the planet gear body 215, or may extend past the outer circumference 215oc of the planet gear body 215 by a distance less than the third gap G3, or be recessed below the outer circumference 215oc of the planet gear body 215.

[0097] FIG. 26 is an enlarged view of a fourth interface between planet and sun gears according to an example of the invention. In FIG. 26, the planet gear 200 and the sun gear 300 may be separated by a fourth gap G4, which, for example, may be within a range of about 0.010 inches to about 0.100 inches. The planet gear 200 may include the plurality of the magnets 225 having, for example, a trapezoidal shape. The magnet 225 includes tapered sides 225s 1 and 225s2, a minor face 225minor, and an opposing major surface 225major. Here, the minor face 225minor has the North magnetic polar orientation and the major face 225major has the South magnetic polar orientation. In addition, the minor face 225minor is disposed within the corresponding groove disposed along the inner circumference 215oc of the planet gear body 215. Here, the minor face 225minor may have a curved surface about equal to the curvature of the outer circumference 215oc of the planet gear body 215. In addition, the curved minor face 225minor may be flush with the outer circumference 215oc of the planet gear body

215, extend past the outer circumference 215oc of the planet gear body 215 by a distance less than the fourth gap G4, or be recessed below the outer circumference 215oc of the planet gear body 215.

[0098] In FIG. 26, the sun gear 300 may include the plurality of the magnets 325 having, for example, a trapezoidal shape. The magnet 325 includes tapered sides 325s 1 and 325s2, a minor face 325minor, and an opposing major surface 325major. Here, the minor face 325minor has the North magnetic polar orientation and the major face 325major has the South magnetic polar orientation. In addition, the minor face 325minor is disposed within the corresponding groove disposed along the outer circumference 310oc of the sun gear body 310. Here, the minor face 325minor may have a curved surface about equal to the curvature of the outer circumference 310oc of the sun gear body 310. In addition, the curved minor face 325minor may be flush with the outer circumference 310oc of the sun gear body 310, extend past the outer circumference 210oc of the sun gear body 310 by a distance less than the fourth gap G4, or be recessed below the outer circumference 310oc of the sun gear body 310. [0099] FIG. 27 is a cross sectional view of an exemplary housing for a planetary gear system according to an example of the invention. In FIG. 27, an exemplary planetary gear system may include a housing having a first outer casing portion OCl and a second outer casing portion OC2. The first outer casing portion OCl includes an upper region OCIa having conical-shaped outer walls, and a central region OCIb that houses a casing bearing CB 1 and allows the rotational shaft 500 to extend therethrough. In addition, the upper region OCIa includes recessed inner walls to accommodate the planet gear carrier plate 220. Here, the upper region OCIa may be connected to the ring gear body 12. Alternatively, the first outer casing portion OCl may be formed integrally with the ring gear body 12.

[00100] In FIG. 27, the second outer casing portion OC2 may include a middle region OC2b disposed between an upper region OC2a and a central region OC2c. The central region OC2c may house a casing bearing CB2 and allow the rotational shaft 600 to extend therethrough, and the middle region OC2b may extend substantially normal to the rotational shaft 600. The upper region OC2a may overlap the ring gear body 12 and the upper portion OCIa of the first outer casing portion OCl . Here, the upper region OC2a may be connected to the ring gear body 12 and to the first outer casing

portion OCl . Alternatively, the second outer casing portion OC2 may be formed integrally with the ring gear body 12. Moreover, the middle region OC2b of the second outer casing portion OC2 may have conical-shaped walls much like the conical-shaped outer walls of the upper region OC 1 a of the first outer casing portion OC 1. Although not shown, the first and second outer casing portions OCl and OC2 may further include various ports in order to monitor operation of the planetary gear system. For example, a Hall sensor may be positioned through a port in the first and/or second outer casing portions OCl and OC2 to measure passing of any of the magnets of the ring, planet, or sun gears. Thus, operational function of the exemplary planetary gear system may be monitored.

[00101] In FIG. 27, the rotational shafts 500 and 600 may be connected to the planet gear carrier plate 220 and sun gear 300, respectively, using, for example, keyless bushing systems, and the case bearings CB 1 and CB2 may be, for example, ceramic bearings. In addition, the torque that can be transmitted by the planetary gear system may be directly related to a first length Ll , which corresponds to the length of the various magnets disposed in the ring, planet, and sun gears. Moreover, a second length L2 of the housing may be varied to accommodate various changes in the first length Ll . [00102] According to the exemplary planetary gear systems of the invention, an inherent safety condition is provided such that if the torque imparted to the system by either the input shaft or the output shaft exceeds the torque handling capacity of one of the magnetic couplings, then a "slip" condition between the magnets of the ring, planet, and sun gears will be invoked to prevent damage to any of the individual components of the planetary gear system, as well as the driving source and load. Thus, until the over-torque condition is brought into acceptable limits, the "slip" condition will continue without any damage to the driving source or load. In addition, the "slip" condition (whether continuous or momentary) will not impede performance of the planetary gear system once the slip condition subsides.

[00103] According to the invention, all three of the ring, planet, and sun gears may be allowed to rotate, for example, for use in a vehicle transmission. Accordingly, the "slip" condition may provide for preventing damage to the transmission, as well as provide additional benefits of use of the planetary gear system according to the present invention.

[00104] FIG. 28 shows an example of a transmission 1500 in accordance with the invention. In FIG. 28, a magnetic planetary gear system 1510 in accordance with the invention is attached to a shaft 1520. The shaft 1520 can be attached to a drive shaft of a vehicle.

[00105] FIG. 29 shows an example of a vehicle 1600 in accordance with the invention. In FIG. 29, a drive motor 1610 is attached to a transmission 1500 (described above), which is in turn attached to a drive shaft 1620. The drive shaft 1620 is attached to a motion transfer system 1630 that transmits the rotation of the drive shaft to a propulsion force for propelling the vehicle. In this example, the motion transfer system 1630 is a wheel. However, various other motion transfer systems, such as, for example, tracks, paddles, propellers, rotor blades, etc., can be used.

[00106] It will be apparent to those skilled in the art that various modifications and variations can be made in the magnetic gear system of the invention without departing from the spirit or scope of the invention.