Electromagnetically-controlled magnetic cycloidal gear assembly and method of operating same

The present disclosure to electromagnetically-controlled magnetic cycloidal gear assemblies and methods of operating same. In one example embodiment, such an assembly includes a stator that is concentric with respect to a primary axis of the assembly, and that includes a plurality of first magnetic devices, where each of those devices includes a respective electromagnet. Also, the assembly includes an input shaft that includes an offset cam, a cycloid mounted at least indirectly upon the offset cam, and an output hub. The cycloid is eccentric with respect to the primary axis and includes a plurality of second magnetic devices, and the output hub is at least indirectly rotationally coupled to the cycloid. The assembly also includes a controller coupled to each of the electromagnets by way of one or more linkages, and configured to govern at least one electric current that is passed through at least one of the electromagnets.

CROSS-REFERENCE TO RELATED APPLICATIONS

FIELD OF THE INVENTION

The present invention relates to gearboxes or gear assemblies or systems, and more particularly to magnetic cycloidal gearboxes or gear assemblies or systems, and methods of operating same.

BACKGROUND OF THE INVENTION

Gear assemblies are used in a wide variety of applications in order to transmit speed and torque from rotating power sources to other devices. Often, a gear assembly operates to communicate, for receipt by another device, output speed and output torque that are different from input speed and input torque that are received from a rotating power source. Various mechanical and magnetic gear assemblies are known. One type of known magnetic gear assembly is the magnetic cycloidal gear assembly.

The general principle of a magnetic cycloidal gear assembly can be understood to involve two circular structures of unequal size, with the larger circular structure being stationary, and with the smaller circular structure being positioned within the interior of the larger circular structure and arranged to be tangent (or substantially tangent) to an interior circular edge of the larger circular structure. Given such an arrangement, the smaller circular structure can be configured to rotate within the inside of the larger circular structure, along the interior circular edge, in an eccentric manner. Such rotational motion can be exploited for gearing when the outer, larger circular structure is a stator and the inner, smaller circular structure is a rotor.

More particularly,FIG.1is a schematic, front elevation view of a conventional magnetic cycloid gear10, having a stator12and a rotor14. The stator12and rotor14are positioned in an eccentric (or non-concentric) manner, such that a rotor axis20is displaced with respect to and not aligned with a stator axis22. An input drive shaft (not shown) that drives the rotor14has a central axis that is aligned with the stator axis22, such that the rotor axis20also is displaced with respect to the central axis of the input drive shaft. Although the rotor axis20is displaced from the central axis of the input drive shaft, the input drive shaft nevertheless is engaged with the rotor14in a manner (e.g., by way of a cam) such that rotation of the input drive shaft causes corresponding rotation of the rotor axis20about the stator axis22, such that the rotor axis20follows a trajectory T (shown in the dashed lines).

Although rotation of the input drive shaft causes rotation of the rotor axis20about the stator axis22that occurs at the same rotational frequency as the rotation of the input drive shaft itself, this is not to say that the entire rotor14rotates at that rotational frequency. Rather, magnetic pole pairs16are arrayed on the stator12and rotor14, and magnetic interactions between those of the magnetic pole pairs of the stator12and rotor14that are closest together depending upon the relative positioning of the stator and rotor at any given time, prevent relative “slipping” motion between the stator and rotor. Consequently, as governed by the interaction of the magnetic pole pairs16, rotation of the input drive shaft causes an outer circular edge24of the rotor14to “roll along” an inner circular edge18of the stator12(with those edges only being separated by an air gap), in an eccentric manner determined by the rotation of the rotor axis20about the stator axis22.

The amount of rotation that is experienced by the rotor14relative to the stator12(as the outer circular edge24of the rotor rolls along the inner circular edge18of the stator) is determined by the difference in the number of pole pairs arranged along the inner circular edge of the stator relative to the number of pole pairs arranged along the outer circular edge of the rotor. In general, because the stator12has more pole pairs along the inner circular edge18than the rotor14has along the outer circular edge24, the rotor14will rotate more than a full revolution for every revolution it travels around the stator12. The gear ratio is based on the number of pole pairs arrayed on the stator as compared to the number of pole pairs arrayed on the rotor. For example, if the stator has m+1 pole pairs, and the rotor has m pole pairs, then the gear ratio between the two is −1/m. In the embodiment ofFIG.1, the gear ratio also effectively corresponds to the difference in the circumferences between the inner circular edge18and the outer circular edge24because magnets of the same size are employed on each of the stator12and the rotor14. However, this is not fundamental and, in other embodiments (e.g., embodiments in which the magnets employed on the stator are sized differently than the magnets employed on the rotor), the gear ratio need not correspond particularly to the difference in the circumferences between the inner circular edge of the stator and the outer circular edge of the rotor.

In a magnetic cycloidal gear assembly, the rotor14is mounted on (or is formed by) a cycloidal disk. Although not shown inFIG.1, it should be appreciated that the cycloidal disk, in addition to being mounted eccentrically on the input shaft as described above, is also typically coupled to an output structure. The output structure serves to output rotational power from the magnetic cycloidal gear assembly. The output rotational torque and speed provided by the output structure typically differ respectively from the input rotational torque and speed (received via the input shaft) in accordance with the gear ratio established by the pole pairs16of the rotor14and the stator12.

Notwithstanding the existence of conventional magnetic cycloidal gear assemblies, such conventional magnetic cycloidal gear assemblies face certain challenges and concerns. Magnetic cycloidal gears assemblies often require large external diameters to achieve the same torque carrying capacity of equivalent mechanical gears (spur, planetary etc.). As such, to act as a direct replacement for mechanical gearboxes in actuation systems, space accommodations must be made, such as increasing the physical envelope or removing other features. Although such accommodations may be possible, such accommodations can involve tradeoffs that result in the loss of features or functions that are desirable.

For example, in the Integrated Servo Actuator and Controller (ISAAC) available from Kaney Aerospace, Inc. of Rockford, Ill., the disengage clutch has been removed to accommodate the magnetic gearbox. Yet removal of the disengage clutch is not preferable. If the disengage clutch were present, the disengage clutch would allow the actuator output to fully disengage and freewheel in certain operational circumstances, such as in the case of a manual override. Additionally, although the magnetic cycloidal gearbox can be back-driven when the motor is unpowered, the back-drive torque is significantly higher than the free-wheel torque that would arise during freewheeling if the disengage clutch were present. This correspondingly can increase the likelihood that the actuator may jam in a manner that is not easily overridden through manual intervention or by way of a parallel actuator, which may be undesirable in some aerospace applications.

For at least one or more of these reasons, or one or more other reasons, it would be advantageous if new or improved magnetic cycloidal gear assemblies or systems could be developed, and/or improved methods of operation of such assemblies or systems could be developed, so as to address any one or more of the concerns discussed above or to address one or more other concerns or provide one or more benefits.

SUMMARY

In at least one example embodiment, the present disclosure relates to an electromagnetically-controlled magnetic cycloidal gear assembly. The magnetic cycloidal gear assembly includes a stator that is fixed and concentric with respect to a primary axis of the magnetic cycloidal gear assembly, and that includes a plurality of first magnetic devices, and also includes an input shaft that is configured to rotate about the primary axis and that includes an offset cam that is offset with respect to the primary axis. Additionally, the magnetic cycloidal gear assembly also includes a cycloid mounted at least indirectly upon the offset cam and configured to rotate both relative to the offset cam and also within the stator, where the cycloid is eccentric with respect to the primary axis and includes a plurality of second magnetic devices. Further, the magnetic cycloidal gear assembly additionally includes an output hub that is concentric with the primary axis and includes a plurality of cam follower receivers, and a plurality of cam followers, each cam follower having a respective first end and a respective second end, where the respective first end of each cam follower is received within a respective one of the cam follower receivers and the respective second end of each cam follower is coupled to the cycloid at a respective location on the cycloid. Additionally, either each of the first magnetic devices or each of the second magnetic devices includes a respective electromagnet configured to produce a respective magnetic field in accordance with a respective current passing therethrough.

Further, in at least one example embodiment, the present disclosure relates to an electromagnetically-controlled magnetic cycloidal gear assembly. The magnetic cycloidal gear assembly includes a stator that is fixed and concentric with respect to a primary axis of the magnetic cycloidal gear assembly, and that includes a plurality of first magnetic devices, where each of the first magnetic devices includes a respective electromagnet. Also, the magnetic cycloidal gear assembly includes an input shaft that is configured to rotate about the primary axis and that includes an offset cam that is offset with respect to the primary axis. Further, the magnetic cycloidal gear assembly additionally includes a cycloid mounted at least indirectly upon the offset cam and configured to rotate both relative to the offset cam and also within the stator, where the cycloid is eccentric with respect to the primary axis and includes a plurality of second magnetic devices, and where each of the second magnetic devices includes a respective permanent magnet. Additionally, the magnetic cycloidal gear assembly also includes an output hub that is concentric with the primary axis and includes a plurality of cam follower receivers, where the output hub is at least indirectly rotationally coupled to the cycloid by way of a plurality of cam followers that are coupled to the cycloid and that respectively interface the cam follower receivers. Further, the magnetic cycloidal gear assembly additionally includes a controller coupled to each of the electromagnets by way of one or more linkages, where the controller is configured to govern at least one electric current that is passed through at least one of the electromagnets so as to produce a magnetic field.

Additionally, in at least one example embodiment, the present disclosure relates to a method of operating a electromagnetically-controlled magnetic cycloidal gear assembly. The method includes providing a stator that is fixed and concentric with respect to a primary axis of the magnetic cycloidal gear assembly, and that includes a plurality of first magnetic devices, where each of the first magnetic devices includes a respective electromagnet. Also, the method includes causing, at least indirectly by way of a controller, at least one current to flow through the respective electromagnets of the first magnetic devices so as to generate a magnetic field. Additionally, the method includes receiving input rotational power at an input shaft having an offset cam about the primary axis, where the offset cam is offset with respect to the primary axis. Further, the method includes, in response to the receiving of the input rotational power, eccentrically rotating a cycloid that is mounted at least indirectly upon the offset cam within the stator, where the cycloid is eccentric with respect to the primary axis and includes a plurality of second magnetic devices, and where each of the second magnetic devices includes a respective permanent magnet. The cycloid eccentrically rotates at least in part due to interactions between the first magnetic devices and the second magnetic devices. Additionally, the method also includes communicating at least one first portion of the input rotational power from the cycloid to an output hub that is concentric with the primary axis and includes a plurality of cam follower receivers, by way of a plurality of cam followers that are coupled to the cycloid and that interface the cam follower receivers, and outputting the at least one first portion of the input rotational power as output rotational power from the output hub.

Notwithstanding the above examples, the present invention is intended to encompass a variety of other embodiments including for example other embodiments as are described in further detail below as well as other embodiments that are within the scope of the claims set forth herein.

DETAILED DESCRIPTION

The present disclosure relates to embodiments of magnetic cycloid gear assemblies or systems, which can also be referred to as magnetic gearboxes, that employ electromagnets in place of at least some permanent magnets that might otherwise be employed in conventional magnetic gearboxes. In at least some such embodiments encompassed herein, the electromagnets are positioned on or as part of the stator in place of permanent magnets that conventionally might be employed on the stator. The electromagnets can be powered or unpowered as needed or depending upon the circumstance. Given this to be the case, the magnetic cycloid gear assembly or system operates as an electromagnetically-controlled (or powered) magnetic gearbox that both can operate as a conventional magnetic gearbox when powered, and also can “disengage” to allow freewheeling of the output when necessary.

Magnetic cycloidal gear assemblies as disclosed or encompassed herein can be used in a wide variety of applications. For example, in some embodiments, such magnetic cycloidal gear assemblies can be incorporated into servo actuators. In at least one example, servo actuators including such magnetic cycloidal gear assemblies of the present technology can be used for aerospace applications such as flight surface control applications. Further, magnetic cycloid gear assemblies of the present technology can be made with various gear ratios, and can have various rotations per minute, depending upon the application or desired level of power output. Although the present disclosure particularly envisions the application or implementation of electromagnets with respect to magnetic cycloidal gear assemblies or systems (or gearboxes), the present disclosure also encompasses embodiments in which electromagnets are applied to other topologies (e.g., other gearbox or transmission topologies) as well.

One example of a magnetic cycloidal gear assembly100that includes electromagnets in accordance with the present technology is shown inFIGS.2,3,4,5, and6. The magnetic cycloidal gear assembly100is shown, in its entirety, inFIGS.5and6, which (among other aspects) illustrate schematically a controller250that serves to govern the providing of power to the electromagnets of the magnetic cycloidal gear assembly, along with associated power/control linkages252. By contrast,FIGS.2and4show portions190of the magnetic cycloidal gear assembly100that omit the controller250and associated power/control linkages252, andFIG.3particularly shows a cycloid104of that gear assembly.FIG.4particularly provides a cross-sectional view of the portions190of the magnetic cycloidal gear assembly100when those portions are fully assembled. The particular cross-sectional view provided inFIG.4is taken along a plane that passes through a schematic primary axis101of the magnetic cycloidal gear assembly100.

As shown inFIGS.2and4, the magnetic cycloidal gear assembly100includes a stator102, a cycloid104, an input shaft106, an output hub108, a bushing214, a plurality of cam followers110, and a counterweight112. The stator102is fixed and concentric with respect to the schematic primary axis101of the magnetic cycloidal gear assembly100, such that the schematic primary axis101intersects a center point103of the stator102when the magnetic cycloidal gear assembly100is assembled and mounted. The stator102is generally annular in shape and has an outer cylindrical surface105and an inner cylindrical surface107. In the present example, the stator102includes a back-iron cylinder118having an outer rim that constitute the outer cylindrical surface105, and additionally a plurality of teeth (e.g., m teeth)120that each protrude radially inwardly from the back-iron cylinder towards the center point103of the stator102.

The stator102also has a number of (e.g., m) electromagnets122, with each of the electromagnets being mounted between a respective pair of the teeth120and facing inwardly towards the center point103of the stator102. Innermost surfaces of the teeth120and of the electromagnets122together form the inner cylindrical surface107of the stator102. Each of the electromagnets122has a respective inner surface along the inner cylindrical surface107and can be powered so that the respective inner surface constitutes a respective positive pole114. When the electromagnets122are powered to provide the positive poles114(along the inner surfaces of those electromagnets), then each of the teeth120is a respective negative pole116. In this regard, the respective teeth120also can be considered respective consequent poles by comparison with the positive poles114provided by the respective electromagnets122.

With such arrangement, the stator102can be understood to include a first number of electromagnetically-generated pole pairs, such as m (or alternatively m+1) magnetic pole pairs, with each magnetic pole pair having a respective one of the positive poles114and a respective one of the negative poles116. Although in this arrangement, it is particularly the positive poles114that are provided by the electromagnets (or windings or coils)122, with the negative poles116being provided by way of the teeth120as consequent poles, this need not be the case in other embodiments. In particular, in some alternate embodiments, electromagnets (or windings or coils) are employed for both the positive and negative poles—that is, certain ones of the electromagnets (or windings or coils) serve as the positive poles while other ones of the electromagnets (or windings or coils) serve as the negative poles.

Referring additionally toFIG.3, the cycloid104serves as a rotor that is configured to rotate within the stator102during operation of the magnetic cycloidal gear assembly100. The cycloid104is mounted eccentrically with respect to the schematic primary axis101of the magnetic cycloidal gear assembly100, such that the schematic primary axis101does not intersect a center point (or center axis)109of the cycloid104when the magnetic cycloidal gear assembly100is assembled and mounted. The cycloid104can be mounted onto the input shaft106by a rolling element bearing162on an offset cam136(seeFIGS.2and4). The rolling element bearing162can be, in an example embodiment, a radial bearing. An outer cylindrical surface111of the cycloid104particularly is the surface that effectively rolls around the inner cylindrical surface107of the stator102(except insofar as an air gap separates the two surfaces) when the cycloid rotates during operation of the magnetic cycloidal gear assembly100.

Further as shown inFIG.3, the cycloid104has a second number of magnetic pole pairs, such as n (or alternatively m) magnetic pole pairs, with each magnetic pole pair having a respective negative pole124and a respective positive pole126. Because the cycloid104is configured to fit and rotate within the stator102during operation as the rotor of the magnetic cycloidal gear assembly100, the number of magnetic pole pairs n of the cycloid is less than the number of magnetic pole pairs m of the stator102. Depending upon the embodiment, the number of magnetic pole pairs n of the cycloid104can be less than the number of magnetic pole pairs m of the stator102by at least one magnetic pole pair, or by more than one magnetic pole pair.

In the present example embodiment, the cycloid104includes a back-iron cylinder (or disk)128having a plurality of (e.g., n) teeth130, and additionally includes a number of (e.g., n) permanent magnets132, with each of the permanent magnets being mounted between a respective pair of the teeth. The permanent magnets132of the cycloid104are arranged to each face outwardly away from the center point109, and also each of the teeth130extends radially outwardly from the back-iron cylinder128, so as to extend in between a respective pair of the permanent magnets132. Given this arrangement, it can be seen that the outer cylindrical surface111of the cycloid104is formed by the radially-outermost surfaces of the permanent magnets132and teeth130. The polarities of the teeth130and permanent magnets132are opposite those of the teeth120and electromagnets122of the stator102when the electromagnets are powered. That is, each of the permanent magnets132of the cycloid104is a respective one of the negative poles124, and each of the teeth130is a respective one of the positive poles126. The respective teeth130also can be considered respective consequent poles by comparison with the respective permanent magnets132.

Notwithstanding the above discussion, the stator102in other embodiments can have any other suitable arrangement that provides magnetic pole pairs. For example, a Halbach array or series of Halbach arrays can be used in place of the back-iron of the stator102. Also, the electromagnets122on the stator102can be arranged to serve as negative poles (in terms of the polarity of the electromagnets along the inner cylindrical surface107), and the teeth120in between those permanent magnets can serve as positive poles. Likewise, in other embodiments the cycloid104(or rotor) can have any other suitable arrangement that provides magnetic pole pairs. Again for example, a Halbach array or series of Halbach arrays can be used in place of the back-iron of the cycloid104. Additionally, the permanent magnets132on the cycloid can be arranged to serve as positive poles (in terms of the polarity of the permanent magnets along the outer cylindrical surface111), and the teeth130can serve as negative poles. Also, different permanent magnets can be employed both to serve as positive poles and also to serve as negative poles on the cycloid.

Further, although in the present embodiment it is the stator102that includes the electromagnets122and the cycloid104that includes the permanent magnets132, in alternate embodiments encompassed herein it is the cycloid that includes electromagnets and the stator that includes permanent magnets. Additionally, in some further alternate embodiments, each of the stator and the cycloid includes electromagnets. In some such embodiments, the electromagnets of the stator can have one polarity (e.g., a positive polarity, or alternatively a negative polarity) and the electromagnets of the cycloid can have the opposite polarity (e.g., a negative polarity, or alternatively a positive polarity). Also, in some alternate embodiments, one or both of the stator and the cycloid include a combination of one or more electromagnets and one or more permanent magnets.

In the present embodiment, the cycloid104is caused to rotate as a result of rotation of the input shaft106. As shown inFIG.2, the input shaft106includes the offset cam136, which is positioned within and supports the cycloid104by way of the rolling element bearing162. In general, the input shaft106is concentric with respect to the schematic primary axis101of the magnetic cycloidal gear assembly100. However, the offset cam136is offset with respect to the schematic primary axis101of the magnetic cycloidal gear assembly100, with one side of the offset cam136extending outwardly from the input shaft106farther than the other side of the offset cam. In the present example embodiment, in which the offset cam136is circular, the offset cam136is concentric with the cycloid104.

As shown inFIG.4, the cycloid104can include a cycloid lip (or shoulder)168, and can be mounted on the rolling element bearing162in part by way of the cycloid lip168. As illustrated, the cycloid lip particularly extends radially inwardly along a side portion of the rolling element bearing162, along the side of the rolling element bearing that is closer to (rather than farther from) the output hub108. Further, the offset cam136includes an offset cam shoulder170that extends radially outward from the remainder of the offset cam alongside the rolling element bearing162, on the side of the rolling element bearing that is farther from (rather than closer to) the output hub108.

In addition to being caused to rotate as a result of rotation of the input shaft106, the cycloid104and magnetic cycloidal gear assembly100more generally are configured so that rotation of the cycloid additionally causes rotation of the output hub108. In this regard, the cycloid104includes a plurality of cam follower retainers134, each of which is configured to receive a respective one of the cam followers110. Each of the plurality of cam followers110has a first end138and a second end140. The second end140of each of the plurality of cam followers110is retained by a respective one of the cam follower retainers134, and is thus fixed to the cycloid104. Further, the output hub108presses against the bushing214, which can be an oil impregnated bushing, and the bushing can also press against the cycloid104. The bushing214can include a plurality of bores221(seeFIG.4), and each of the plurality of cam followers110can pass through a respective one of the bores221. The plurality of cam followers110can thus connect the bushing214to the cycloid104.

It should be appreciated that the exact arrangement of the bushing214, cam followers110, and cam follower retainers134can vary depending upon the embodiment. For example, any suitable number of the cam follower retainers134and any suitable number of the bores221can be included, preferably at least two of each, or more than two of each, such as three, four, five, or more than five. For example, in the present embodiment, six of the cam follower retainers134and six of the bores221are present in the cycloid104and the bushing214, respectively. Likewise, any suitable number of the cam followers110can be included in the magnetic cycloidal gear assembly100. Accordingly, at least two of the cam followers110can be provided, or more than two, such as three, four, five, or more than five. For example, in the present embodiment, six of the cam followers110are present. Preferably a respective one of the cam followers110is provided for each of cam follower retainers134of the cycloid104.

The cam followers110particularly allow for rotational motion of the cycloid104to be communicated to the output hub108, which is concentric with the schematic primary axis101of the magnetic cycloidal gear assembly100. The output hub108includes an output disk142, an output shaft144, and an intermediate portion164positioned between the output shaft and output disk and having a diameter that is larger than that of the output shaft. The output shaft144is concentric with the schematic primary axis101, can be connected to another device, and can be used to transmit the speed and torque output (or generated) by the magnetic cycloidal gear assembly100to another device (not shown). The output disk142includes a plurality of cam follower receivers146. Each of the cam follower receivers146has a receiver radius (or diameter) that is larger than a first end radius (or diameter) of each of the first ends138of each of the cam followers110. By virtue of this difference in size of the receiver radius and first end radius, the respective first end138of each of the cam followers110can rotate eccentrically within the respective one of the cam follower receivers146in which that first end is positioned, even though the output hub108and cam follower receivers146thereof do not vary in their radial positioning relative to the schematic primary axis101.

From the above discussion, it should be appreciated that the output hub108is interactively connected to the cycloid104by the cam followers110, and the cam followers110transmit output torque and rotation from the cycloid104to the output hub. That is, as the cycloid104rotates relative to the stator102, rotational power is transferred from the cycloid104to the output hub108by way of the plurality of cam followers110and their interactions with the cam follower receivers146. The use of the plurality of cam followers110can eliminate the need for rolling pin elements, and can significantly reduce the rolling resistance and therefore improve the efficiency of the magnetic cycloidal gear assembly100as compared to some conventional magnetic cycloidal gear assemblies. Additionally, oil (or other lubricant) can be delivered to the bores221, and thereby to the cam followers110, the cam follower receivers146, and the interface between output hub108and the bushing218to facilitate relative movement of these component parts (and especially any sliding movement of the bushing relative to the output hub).

In some embodiments, also encompassed herein, each of the cam followers110can include a respective roller bearing (or similar rolling head or wheel feature) at the respective first end138of the respective cam follower, as a respective head of the respective cam follower. With such an arrangement, movement of the cam followers110within the cam follower receivers146entails rotational motion of the roller bearings relative to the remaining portions of the cam followers (e.g., the second ends140), and sliding motion (and consequent friction) of the cam followers relative to the cam follower receivers is lessened or avoided. Also, in some embodiments encompassed herein, a set of rolling element bearings that are fixed to the cycloid104operate to transmit torque from the cycloid to the output hub108.

FIG.4additionally illustrates how the input shaft106and output hub108are supported relative to one another. In the present embodiment, an input shaft receiver165(which defines an input shaft receiving orifice) is provided within the output hub108and particularly extends inwardly from the end surface of the output disk142and into the intermediate portion164, toward (but not up to) the output shaft144. The input shaft receiver165is configured to receive a first end166of the input shaft106as well as an input shaft bearing212. More particularly, the input shaft bearing212can be inserted into the input shaft receiver165, and the first end166of the input shaft106can be inserted into the input shaft bearing. The input shaft bearing212can be a roller bearing, and can prevent radial movement of the input shaft106while allowing the input shaft106to rotate within the input shaft receiver165. Therefore, the input shaft106(at least the first end166of the input shaft) is rotatably supported upon and within the output hub108by way of the input shaft bearing212.

As for the counterweight112, as shown inFIGS.2and4, the counterweight is attached to the input shaft106. The counterweight112can have a clamp148, a first lobe150and a second lobe152. The clamp148can attach the counterweight112to the input shaft106such that the counterweight112can rotate with the input shaft106. The counterweight112can balance out the mass imbalance caused by the rotation of the eccentrically mounted cycloid104.

Referring additionally toFIGS.5and6, front elevation views are provided to illustrate the magnetic cycloidal gear assembly100at different times during operation, at which the cycloid104has two different positions relative to the stator102.FIG.5particularly provides a front elevation view of the magnetic cycloidal gear assembly100when the cycloid104is in a first position, which corresponds to what is shown inFIG.4(in terms of the rotational orientation of the cycloid104about the schematic primary axis101). By contrast,FIG.6provides a front elevation view of the magnetic cycloidal gear assembly100when the cycloid104is in a different, second position. Thus, the relative rotation of the rotor (cycloid104) and stator102of the magnetic cycloidal gear assembly100can be seen by comparingFIG.5withFIG.6. Additionally it should be appreciated thatFIGS.5and6also show corresponding different positions of other components or portions of the magnetic cycloidal gear assembly100that also vary in their positions when the cycloid varies in its rotational positioning.

As will be appreciated from the above discussion, movement of the cycloid104results from rotation of the input shaft106and offset cam136, which causes different ones of the positive poles114and negative poles116of the stator102to come into proximity with different ones of the negative poles124and positive poles126of the cycloid104. Due to the interactions between these pole pairs, slipping motion between the outer cylindrical surface111of the cycloid104and the inner cylindrical surface107of the stator102is prevented. Stated in another manner, the magnets in essence prevent “slippage” of the cycloid104(serving as the rotor) relative to the stator102and thus, due to the magnetic interaction between the pole pairs of the stator102and the pole pairs of the cycloid104, the cycloid rotation couples to the input shaft rotation as the magnets continue to seek their state of lowest potential (relatedly, it can be said that the magnetic forces provide the torque reaction allowing for the gearbox to transmit torque from input to output, as the cycloid would otherwise just spin on its bearing).

Consequently, as governed by the interaction of the magnetic pole pairs on the cycloid104and stator102, rotation of the input shaft106and offset cam136causes the outer cylindrical surface of the cycloid104to “roll along” the inner circular surface107of the stator102(with those surfaces only being separated by an air gap), in an eccentric manner. The first position ofFIG.5(andFIG.4) shows the magnetic cycloidal gear assembly100at the start of a 360° revolution of the input shaft106(and offset cam136), when the position of the cycloid104is closest to the uppermost portion of the inner cylindrical surface107of the stator102. By comparison, the second position ofFIG.6is half way through the revolution of the input shaft106, at 180° from the first position, when the position of the cycloid104is closest to the lowermost portion of the inner cylindrical surface107of the stator102.

The particular gear ratio achieved between the input rotation experienced by the input shaft106and the output rotation experienced by the output hub108depends upon the relative numbers of magnetic pole pairs on the stator102and on the cycloid104. If one assumes, as shown inFIGS.5and6, that the cycloid104has one fewer magnetic pole pair than the stator102, then for every full rotation of the input shaft106, the cycloid104must rotate one full rotation plus and additional amount to make up the difference. Supposing for example that the stator102has m+1 pole pairs and the cycloid104has m pole pairs, for a point on the cycloid after one full rotation of the input shaft106, the point will have moved to a position equivalent to −1/m rotations, where the negative sign indicates that the rotation is in the opposite sense to the rotation of the input shaft.

Because the cycloid104is supported upon the offset cam136and rotates eccentrically within the stator102, and given the magnetic interactions between the cycloid104and stator102, the amount of air gap (or space) between the stator102and the cycloid104varies at any given point around the inner cylindrical surface107of the stator102as the cycloid104rotates. Nevertheless, there is always a minimum gap220between the stator102and the cycloid104at a first point and a maximum gap222at a second point, and the locations of those points rotate as the cycloid104rotates in response to rotation of the input shaft106and offset cam136. The minimum gap220particularly always is in line with the high point of the offset cam136.

For example, as can be seen with reference toFIG.5(andFIG.4), when the cycloid104is in the first position, the minimum gap220between the stator102and the cycloid104is at the top (as illustrated inFIGS.5and4) of the stator102and the cycloid104, and then the maximum gap222is at the bottom of the stator102and the cycloid104. In contrast, as can be seen with reference toFIG.6, when the cycloid104in the second position, the minimum gap220between the stator102and the cycloid104is at the bottom (as illustrated inFIG.6) of the stator102and the cycloid104, while the maximum gap222is schematically at the top of the stator102and the cycloid104.

FIGS.5and6additionally show how other components or portions of the magnetic cycloidal gear assembly100rotate or otherwise move in conjunction with rotation of the input shaft106and offset cam136and consequent movement of the cycloid104. In particular,FIG.5shows that, when the cycloid104is in the first position, each of the first ends138of the respective cam followers110is at the respective top of the respective cam follower receiver146into which the respective first end is positioned. In contrast,FIG.6shows that, when the cycloid104is in the second position, each of the first ends138of the respective cam followers110is at the respective bottom of the respective cam follower receiver146into which the respective first end is positioned. Thus, the eccentric rotation of the cam followers110within the cam follower receivers146that accompanies the eccentric rotation of the cycloid104can be appreciated fromFIGS.5and6.

As noted above,FIGS.5and6show the entire magnetic cycloidal gear assembly100of the present embodiment and, more particularly, each ofFIGS.5and6(in contrast toFIGS.2and4) also shows schematically the controller250for governing actuation of the electromagnets122of the stator102of the magnetic cycloidal gear assembly100, along with the associated power/control linkages252. It should be appreciated that the controller250can take any of a variety of forms depending upon the particular embodiment or implementation. For example, the controller250can take the form of a microprocessor or computer, including a computerized device that operates in accordance with software. Also for example, the controller250can take the form a hardwired control device or a programmable logic device, or multiple such devices, or a drive.

Preferably, the controller250is able to output electric power (and particularly current) to the electromagnets122by way of the power/control linkages252that is sufficient to enable the electromagnets to generate sufficient magnetic fields to allow the magnetic cycloidal gear assembly100to transmit rotational power. Depending upon the embodiment, the controller250can operate independently or, alternatively, the controller250can operate at least partly based upon or in response to commands, control signals, or information received by way of wired or wireless communications from another device, source, or location, including for example a remote controller or from the cloud (not shown). Also, in at least some embodiments, the controller250operates directly or indirectly based upon or in response to operator input commands or signals, and/or based upon or in response to sensed information, including for example information regarding the speed or torque of the input shaft106or regarding the speed or torque of the output shaft144(or structure(s) coupled thereto).

With respect to the power/control linkages252, the manner in which these are illustrated inFIGS.5and6is merely intended to be illustrative of the existence of connections between the controller250and the electromagnets122by which electric power (and particularly current) can be provided to the electromagnets so that magnetic fields are generated by the electromagnets. The exact number and type of structures that are employed as the power/control linkages252can vary depending upon the embodiment. In the present example, the power/control linkages252include a first linkage254and a second linkage256. Each of the first and second linkages254and256extends from the controller250to the stator102and then, within (or alongside) the stator, is coupled to each of the electromagnets252. (For simplicity of illustration, the portions of the first and second linkages254and256that are within the interior of or alongside the stator102are illustrated by dashed lines, with only some portions of the linkages connected to some of the electromagnets122being shown, and other portions being cutaway and not shown.) Although the manner in which the first and second linkages254and256are shown inFIGS.5and6indicates that all of the electromagnets252are electrically coupled in parallel with one another between the first linkage254and the second linkage256, it should be appreciated that all of the electromagnets can alternatively be coupled in series between the first linkage254and the second linkage256.

Given this embodiment, when electric power (particularly current) is directed from the controller250to the electromagnets122via the first linkage254(or alternatively the second linkage256), that electric current is directed to and passes through the electromagnets and then returns via the second linkage256(or alternatively the first linkage254). During such operation, all of the electromagnets122turn “on” in response to the current conducted therethrough, and all of the electromagnets are simultaneously activated in terms of producing magnetic fields. Correspondingly, when the controller250ceases to direct electric power (particularly current) through the first linkage254(or alternatively the second linkage256), then all of the electromagnets122are turned “off” and simultaneously deactivated such that no magnetic fields are generated by the stator102.

In the present embodiment, the controller250particularly is configured to cause electric power (and current) to pass through the electromagnets122during a normal mode of operation, but to cease directing electric power (and current) flow through the electromagnets during a clutch mode of operation, when clutch functionality is desired. During normal operation when it is desired that the magnetic cycloidal gear assembly100generate output rotation at the output hub108in response to input rotation of the input shaft106in accordance with the gear ratio established by the pole pairs of the stator102and cycloid104, the controller250actuates the electromagnets122to prevent slippage between the cycloid and the stator as discussed above.

However, when the electromagnets122are disabled during the clutch mode of operation (or possibly under other special circumstances when normal operation is not desired), the electromagnets of the stator102and permanent magnets132of the cycloid104will no longer prevent slipping between the cycloid and stator, and the magnetic cycloidal gear assembly (or gearbox)100will be able to freewheel. Stated in another manner, the electromagnets122and permanent magnets132in this circumstance no longer provide a torque reaction, and any torque applied at the input or output will simply cause the rolling element bearing162to spin. In such circumstance, the freewheel torque (e.g., as provided at the output shaft108) will be a function only of the drag caused by the rolling elements, the inertia of the cycloid104, and any secondary electromagnetic effects caused between the magnets and the unenergized electromagnets122(or windings or coils).

It should be recognized that magnetic cycloid gear assemblies of the present technology can be supported or implemented within any of a variety of types of structures depending upon the embodiment, and can be employed in any of a variety of applications. Referring toFIG.7, in one example embodiment, the magnetic cycloidal gear assembly100can be contained within a housing300. As shown, the housing300includes an outer shell302that encloses the magnetic cycloidal gear assembly100. The housing300can also include a front cover304, which can be a removable access panel that, when removed, provides access to the inside of the housing300and the magnetic cycloidal gear assembly100. Additionally, the housing300can include one or more additional support and/or mounting structures to support, mount, or otherwise engage with the magnetic cycloidal gear assembly100.

For example, as shown inFIG.7, the housing300can include a connector306, which engages and connects at a first end to the output shaft144of the output hub108and at a second end to another device to transfer rotational power from the magnetic cycloidal gear assembly100to the other device, which can be external to the housing. If the input shaft106is also driven by a rotational power source external to the housing, a further connector (not shown) can also be provided to couple the input shaft with that rotational power source. Also for example, internally within the housing300, support and/or mounting structures (not shown) can be provided to support or mount the magnetic cycloidal gear assembly100within the housing300.

It should be appreciated that, in at least some embodiments, the controller250and power/control linkages252can be positioned with the housing300but that, in other embodiments, the controller250and/or portions of the power/control linkages252can be located outside of the housing even though other portions (e.g., the portions190discussed above) are positioned within the housing300. Also, it should further be appreciated that, although for purposes of the above discussion the magnetic cycloidal gear assembly100is considered to be distinct from (and situated within) the housing300, and is considered to not include the housing or any of the support or mounting structures or components associated therewith, nevertheless the magnetic cycloidal gear assembly can also be understood to include the housing and/or any such support or mounting structures or components.

In view of the above discussion it should be appreciated that the magnetic cycloidal gear assembly100described in regard toFIGS.2,3,4,5, and6can be operated in several modes of operation by virtue of the controller250causing the electromagnets122to be powered or unpowered. Referring toFIG.8, a flow chart800is provided to illustrate example steps of one example method of operation of the magnetic cycloidal gear assembly100in this regard. Notwithstanding what is shown inFIG.8, however, it should be understood that the present disclosure is intended to encompass numerous other methods of operation and associated steps of operation for magnetic cycloidal gear assemblies such as the magnetic cycloidal gear assembly100or other assemblies or systems, and is not limited to the method shown inFIG.8.

More particularly with respect to the method of operation illustrated by the flow chart800, the method begins at a first step802, at which a stator having magnetic devices including electromagnets is provided, such as the stator102with the electromagnets122. The first step802can also be considered an initial step at which the entire structure of the magnetic cycloidal gear assembly100is provided or set up for operation. Next, at a second step804, the controller250causes electric power (particularly current) to flow through the electromagnets122so as to generate magnetic fields. Further, at a third step806, rotational power transmission operation of the magnetic cycloidal gear assembly100begins insofar as input rotational power is received at the input shaft106including the offset cam136, such that the input shaft and offset cam rotate.

Then, at a fourth step808, the cycloid104is caused to eccentrically rotate within the stator102in response to the rotation offset cam136, consistent with magnetic interactions between the permanent magnets of the cycloid and the electromagnets122of the stator102. Further, at a fifth step810, at least one portion of the received input rotational power is communicated from the cycloid104to the output hub108. In at least the present embodiment, the communication of this rotational power occurs due to interactions of the cam followers110with the cam follower receivers146of the output hub108. Additionally, at a sixth step812, the at least one portion of the input rotational power is output via the output hub (e.g., for receipt by a load or receiving device).

All of the steps804,806,808,810, and812can be considered to occur at a first time (or during a first time period) during which the magnetic cycloidal gear assembly100is operating in a normal mode of operation of the magnetic cycloidal gear assembly100. During such normal operation, the magnetic cycloidal gear assembly100operates to transmit rotational power between the input shaft106and the output hub108, with the rotational power being modified in terms of the rotational speed and torque in a manner consistent with the gear ratio of the magnetic cycloid gear assembly. However, as described above, in a clutch mode or other mode of operation of the magnetic cycloidal gear assembly, it can be desired that the output hub108be decoupled from the input shaft106so that the output hub experiences freewheeling.

In this regard, the method ofFIG.8additionally includes a seventh step814, at which the controller250ceases causing the electric power (and electric current) to be provided to the electromagnets122of the stator102, such that the electric power (and current) ceases to flow through those electromagnets. Upon this occurring, then at an eight step816, the output hub816becomes rotationally decoupled from the input shaft106and freewheeling of the output hub is permitted. Although not shown inFIG.8, it should be appreciated that the steps of the flow chart800can be repeated such that the magnetic cycloidal gear assembly100repeatedly switches between operation in the normal mode and operating in a mode where freewheeling is possible. For example, upon completion of the eight step816, the method can return to the step804at which electric power (and current) is again caused to flow through the electromagnets during a return to the normal mode of operation.

Notwithstanding the above description, the present disclosure is intended to encompass numerous alternate embodiments. For example, although the electromagnets can be located on the stator102as shown inFIGS.2,4,5, and6, electromagnets can alternatively be mounted on the cycloid104(or rotor), or be mounted on each of the stator and the cycloid. Also, althoughFIGS.2through6concern the application of electromagnets and electromagnetic control to a particular example topology of a magnetic cycloidal gear assembly, the present disclosure is intended to encompass numerous other typologies including not only other typologies of cycloidal gears but also other topologies such as ones involving coaxial magnetic gears, magnetic spur gears, and other types of gears and gear arrangements.

Additionally, notwithstanding the above description, the controller250and power/control linkages252can take a variety of other forms depending upon the embodiment or circumstance. For example, in some alternate embodiments, the power/control linkages include a plurality of different linkages that are respectively coupled to different respective ones of the electromagnets122. In such embodiments, all of the electromagnets122need not be powered simultaneously. Rather, the controller250can actuate the different ones of the electromagnets122at respectively different times or in respectively different manners. Further for example, in some such embodiments, different respective actuating electrical currents can be applied by the controller250respectively to different ones of the electromagnets122so that different respective magnetic fields are generated by the different electromagnets (e.g., magnetic fields with different magnitudes or occurring at different times). Also, although it is envisioned that the controller250will provide direct current (DC) power to the electromagnets122in the magnetic cycloidal gear assembly100ofFIGS.2through6described above, in other embodiments other forms of power (or current or voltage) can be provided to one or more of the electromagnets, such as alternating current (AC) power.

The present disclosure further envisions and encompasses alternate embodiments in which the operation of electromagnets as controlled by a controller (e.g., via power/control linkages) occurs in any of a variety of different or additional manners. In at least some such alternate embodiments, control of the electromagnets (or windings or coils) permits improved performance of the magnetic cycloidal gear assembly (or gearbox) by comparison with magnetic cycloidal gear assemblies (or gearboxes) that only employ permanent magnets but not electromagnets. Also, in at least some such alternate embodiments, the electromagnets (or windings or coils) can be controlled in any of a variety of modulated manners to achieve any of a variety of goals.

For example, in one such alternate embodiment, the controller can operate to modulate the electromagnets on the stator (e.g., the stator windings or coils) to “lead” the cycloid, so as to improve the output speed of the system at a given input torque over what a motor alone would be able to achieve. Also for example, in an additional such alternate embodiment, the controller can operate to modulate the electromagnets on the stator (e.g., the stator windings or coils) in a manner such that the gearbox operates at a different gear ratio than the inherent gear ratio, potentially optimizing for motor power or some other parameter. Further for example, in another such alternate embodiment, the controller can operate to modulate the electromagnets on the stator (e.g., the stator windings or coils) in a manner that reduces or minimizes the forces on the input shaft (e.g., magnetic and centripetal forces), so as to reduce the burden on the shaft and bearings, and potentially reduce the size and weight of the counterweight/counterbalance.

Additionally for example, in a further such alternate embodiment, the controller can operate to modulate the electromagnets on the stator (e.g., the stator windings or coils) in a manner that is independent of the motor to provide small or high frequency position adjustments. Also for example, in an additional such alternate embodiment, the controller can operate to modulate the electromagnets on the stator (e.g., the stator windings or coils) with respect to torque to improve the stiffness of the gearbox. Although each of these alternate embodiments involving various types of modulation particularly involves modulation of the electromagnets on the stator (or the power or currents delivered thereto), the present disclosure also is intended to encompass embodiments that involve modulation of electromagnets on a cycloid or rotor, instead of (or in addition to) modulation of electromagnets on a stator.

One or more of the embodiments encompassed herein can be advantageous in any of a variety of respects. For example, in at least some embodiments, the benefits of the technology include the ability to achieve very high gear ratios in a single stage, true zero-backlash operation, as well as reduced wear, reduced noise and improved reliability and life due to the lack of mechanically meshing gear teeth. Also for example, with respect to at least some embodiments encompassed herein, because the magnetic cycloidal gear assemblies (or gearboxes) employ electromagnets, the magnetic cycloidal gear assemblies can operate both as conventional magnetic gearboxes when powered (e.g., during a normal mode of operation), and also can “disengage” to allow freewheeling of the output when necessary (e.g., during a clutch mode of operation). Further for example, with respect to at least some embodiments encompassed herein, any of a variety of different types of control over the actuation and deactivation (and/or modulation) of one or more of the electromagnets of a magnetic cycloidal gear assembly can be performed in order to achieve any of a variety of different types of operation. Additionally, the present disclosure is not limited to the embodiments employing magnetic cycloidal arrangements but rather encompasses embodiments having other structures and arrangements as well.