This invention relates generally to the field of mechanical gears, and more specifically to a new and useful system for alternative gearing solutions.
Motor drives, transmissions, and gears are critical parts of robotics, manufacturing, automation, and many other fields. Such components must be carefully selected based on the performance requirements of a part's intended use. In many cases, this may mean using a variety of parts possibly from different vendors to accommodate different performance targets. Even more problematic is that, in some cases, a part with a particular performance property may not be readily available and may need to be custom made.
In particular, strain wave gears are one critical type of mechanical gearing system. Strain wave gears include a wave generator, a flex spline, and circular spline. The strain wave gear can provide high torque density—offering high torque in a relatively compact space and low weight. The strain wave gear can achieve high gear reduction ratios of 30:1 to even 320:1 in a space where planetary gears may only provide 10:1. Strain wave gears are additionally cited as providing “zero backlash”. However, such claims do not reflect true lifetime properties of a strain wave gear. Wear between the teeth leads to eventual backlash. Additionally, strain wave gears are very expensive and complex to manufacture. Individual parts are often individually customized almost to a molecular level to pair with other parts for a single unit. Other forms of drives include cycloidal drives. Cycloidal drives are generally heavier and are not typically backdrivable. Thus, there is a need in the gearing field to create a new and useful customizable planetary frictional gear system. Thus, there is a need in the mechanical gear field to create a new and useful system for alternative gearing solutions. This invention provides such a new and useful systems.
The following description of the embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention.
As shown in
As an exemplary application, gearing segments no can be hinged components that can be interconnected into varying sizes of rings with a continuous gearing surface. The diameter of a resulting gearing configuration (i.e., an assembled gear system) could be increased by adding one or more gearing segments no, and the diameter could be reduced by removing one or more gearing segments 110 as shown in
The modular gearing system is preferably used with a physical gearing system that can include non-parallel / perpendicular gearing (e.g., using traditional gear teeth engagement structures) and/or parallel gearing.
Perpendicular gearing (i.e., non-parallel gearing) is characterized as having gear teeth or physical structures that are defined along a direction that is not parallel to the rotation or translation path of a transmission/assembly during engagement with another gear component. At least one portion of the direction vector of a perpendicular gear tooth is perpendicular to the direction or rotation or translation. As another characteristic, perpendicular gearing includes gear teeth that are non-continuous. Perpendicular gearing includes gearing surfaces that include gear teeth with structure similar to a spur or straight-cut gear, a helical gear, a hypoid gear, a bevel gear, or any suitable type of gear tooth that extends across the width of the gearing surface.
Parallel gearing is characterized as having physical structure features (e.g., frictional contact surface, longitudinal grooves/teeth, perimeter grooves) that are defined along a direction that is parallel to the rotation path during engagement with another gear component. More specifically, the “teeth” of the gear are defined along a direction that is parallel to the tangent of the rotational arc of an engaged gear component. Another characteristic of parallel gearing can be gear teeth (or more specifically longitudinal structures or “grooves”) that are continuous along the length of a gearing system. A connected gearing surface with parallel gearing has gear teeth bridging between different gearing segments no. In other words the number of gearing segments does not alter the number of “gear teeth” in a parallel gearing variation. However, stacking and other alternatives may be employed to alter the number of “gear teeth”. The parallel gearing preferably operates at least partially through frictional surface interactions. Herein, such frictional contract surface features used for parallel gearing are generally referred to as longitudinal structures.
The modular gearing system could alternatively be used in magnetic gearing where inter-gear engagement occurs through magnetic field interactions or any suitable type of gearing.
The set of gearing segments 110 function to be connectable components that can be interconnected into different gearing configurations. A gear segment 110 preferably includes a base structure 112 that connects a gearing surface 120 and preferably two segment connectors 130. A gearing segment 110 preferably includes a length of gearing surface 120 with a segment connector 130 at opposing sides as shown in
A gearing segment 110 preferably includes at least one gearing surface 120. A gearing segment 110 could alternatively include two or more gearing surface as shown in
A gear segment can additionally include a fixture structure 114 that functions to facilitate physical/mechanical coupling to a gear brace 140. The fixture structure 114 is preferably on a surface opposite that of the gearing surface 120. In one implementation, the fixture structure 114 includes a rigid structure with at least one defined through hole that facilitates bolting of a gear segment to a gear brace 140. The set of gearing segments 110 are preferably of uniform segment size. However, a variety of segment sizes may be used.
In a link variation, a gearing segment 110 can be a gearing link 116 that includes a rigid base structure 112 as shown in
In a strip variation, a gearing segment 110 can include a flexible base structure as shown in
The gearing surface 120 of a gear segment 110 functions as the mechanism by which rotation and/or translation can be transferred to an engaged gear components. A gearing surface 120 can use physical gearing structures. Physical gearing structures can use parallel gearing or perpendicular gearing. Alternatively, magnetic gearing can be used where static magnetic regions or electromagnetically controlled regions can be arranged with alternating poles as shown in
A parallel gearing variation can include a gearing surface 120 with longitudinal structures (e.g., parallel grooves). A parallel gearing variation can be a rigid gearing link as shown in
A system variation that includes a parallel gearing surface 122 may be used with additional parallel gearing components such as a pressure control mechanism to promote frictive contact and may be used for particular configurations such as the planetary frictional gear system that employ parallel gearing as described below.
In a perpendicular gearing variation, the gearing surface can include a perpendicular gearing surface 124 with gear teeth structures periodically repeated longitudinally. Helical gear teeth configurations could similarly be used as a variation of a more general non-parallel gearing variation. The perpendicular gearing variation is preferably used in combination with a flexible gearing segment strip. The profile of the gear teeth may be adjusted to account for an operable range of flexibility. A perpendicular gearing variation could alternatively use a rigid gearing link variation of a gearing segment no.
The segment connector 130 functions to interconnect at least two gearing segments no. The segment connector 130 can be any suitable type of fastener, structure, or mechanism to support fastening two gearing segments no. The segment connectors 130 can all be uniform. Alternatively, there may be complementary (e.g., male and female versions) segment connectors 130, which may promote a particular side alignment of two gearing segments no.
Preferably, a segment connector 130 can have at least three connection modes: a disconnected mode, a rotation connection mode, and a fixed connection mode. The segment connectors 130 can preferably be disconnected and reconnected in setting up a gearing configuration. The disconnected mode is when a segment connector 130 is not connected to another segment connector 130. The rotation connection mode preferably enables rotation or flexibility between two gearing segments no. A fixed connection mode preferably rigidly restrains the relative angle between two gearing segments no. Such different modes may not be used or may not be discrete.
In some cases, the base structure is designed to accommodate intermeshing of two segment connectors. For example, defined indents may be provided in areas surrounding the segment connectors as shown in the side profile of a parallel gearing segment in
In a flexible gearing segment strip variation, the gearing segment is substantially continuously flexible across the length of the strip—the segment connector 130 design when connected is preferably similarly flexible.
As another variation, the segment connector 130 can include rotation restraints to limit the range or rotation between two interconnected gearing segments. In a similar variation, the segment connector can include a set of periodically spaced stable states through indents or other mechanical features such that discrete angles can be snapped into place. Various other features may additionally be include to enable mechanical conveniences in aligning, positioning, and locking interconnected gearing segments no.
In one exemplary implementation, the segment connector 130 can be a physical structure feature of a gearing link where a defined through-hole cavity is included at either end of the length of the gearing link as shown in
The gear brace 140 functions to provide a rigid support to a set of interconnected gear segments 110 in a gearing configuration. The gear brace 140 preferably provides rigidity and can restrict the form of the gearing configuration during use of the gearing configuration. In some variations, the gear brace 140 can be optional, and the system may not use a gear brace 140. For example, the segment connector 130 may be sufficient in restricting relative motion between interconnected gearing segments 110 when in a fixe connection mode.
The gear brace 140 can be a multi-party component that can be fixed in place. The gear brace 140 may alternatively be a modular system that is build by a set of interconnected gear brace segments.
The design of a gear brace 140 may differ depending on the type of gearing configurations supported by the system. Gear braces 140 may go around, within, along the side, or physically couple with a set of gearing segments no in any suitable manner. An exemplary set of gear brace variations can include an outer circular gear brace 142, an inner circular gear brace 144, a linear gear brace 146, and/or any suitable type of gear brace 140.
The outer circular gear brace 142 is preferably used with a gearing configuration that is an annular ring with an internal gearing surface. The outer circular gear brace 142 can substantially circumscribe the gearing configuration, preferably being able to be physically coupled to the set of gearing segments at multiple locations as shown in
The inner circular gear brace 144 is preferably used with a gearing configuration that is circular (or alternative shaped gear) with an external gearing surface. The inner circular gear brace 144 can fit within a defined cavity of interconnected gear segments as shown in
The outer circular gear brace 142 and the inner circular gear brace 144 can preferably adjust and/or accommodate different diameters. In one variation shown in
The linear gear brace 146 is preferably used for bracing different lengths of linear gear configurations as shown in
A gearing configuration is preferably reconfigurable such that the components can be disconnected and used in a different combination to create a different gearing configuration. The gearing brace no and the set of gearing segments can be disconnected and reused.
Alternatively though, the components of the system may be initially configured and then substantially permanently set in a gearing configuration. For example, an epoxy or material can be used as the gearing brace and used to set a gearing configuration. For example, an inner circular gear brace can be a composite material that is set within a defined cavity that substantially binds the interconnected gearing segments as shown in
In one variation, the system can additionally include an inter-stack brace 150 as shown in
Additionally, two or more sub-gearing configurations may be interconnected in a staged gearing configuration when connected through an inter-stack brace, which is substantially similar to the stacked gearing configuration but internal gearing components may be coupled for non-one-to-one arrangement. This can be particularly useful where the gearing segments are used to form an annular ring configuration with an internal gearing surface. Internal gear components can be set to engage with the internal gearing surface, and those gear components can be coupled between different stages to alter the gear ratios.
As discussed the system can be used to create a variety of gearing configurations. Different implementations of the system can be used for different types of configurations. Some system implementations may support multiple gearing configuration types. The system can support circular configurations of different sizes and with internal or external gearing surfaces. Alternative shape configurations such as ellipses or arbitrary smooth shape forms could similarly be supported. The system can support linear configurations of different lengths. The system can additionally support non-linear, continuous paths.
As shown in
The parallel gearing system may additionally include periodic protrusions 216 along the first gear component 210 that complimentary work with a planetary module variation of the second gear component. The parallel gearing system may additionally include a pressure control mechanism 230.
A parallel gearing system can be used with the modular gearing system described above, but may alternatively be manufactured and produced as a non-modular system.
The first gear component 210 and second gear component 220 function as at least the two gear components that transmit rotation and/or translation through a parallel gearing interaction. As with non-parallel gearing systems, there may be a wide variety of configurations and arrangements of these two or more gear components.
Parallel gearing can be used for a variety of applications such as linear gear systems (e.g., rack and pinion configuration), arbitrary gear paths, external gears, internal gears, bevel gears, and other suitable arrangements. As described below, parallel gearing can be particularly applicable to a planetary frictional gear system that can be used as an alternative and potential improvement over harmonic drives, cycloidal gearing systems, and/or other gearing systems.
As shown in
In one configuration of a contained gearing system, the first gear component 210 can be an annular ring with internal gearing surface 212, and the second gear component 220 can be a circular disk as shown in
The first gear component 210 and second gear component could alternatively be circular gears with outer gearing surfaces. Preferably, a pressure control mechanism 230 can promote appropriate contact pressure.
The gearing surface 212, which includes a set of longitudinal structures 214, and the gearing surface 222, which includes complementary longitudinal structures 224, functions to act as the gear teeth. In some respects the longitudinal structures 214 and 224 promotes increased friction and longer life of the gearing surface. Additionally, the longitudinal structures 214 and 224 can facilitate reduced backlash due to potentially a tighter fit and increased surface area contact. In other respects, the longitudinal structures 224 promote alignment. The pattern of the longitudinal structure is preferably a set of grooves (or conversely ridges, but herein grooves are used as the descriptor). The longitudinal structures 214 preferably extend along the length of a gearing surface as shown in
The grooves can have any suitable shape profile, such as a triangular pattern, a square pattern as shown in
The gearing surface 212 preferably includes periodic protrusions 216 that interact with the second gear component 220. The periodic protrusions 216 function to provide a secondary physical coupling interaction. Preferably, the periodic protrusions prevent gross slippage between the two gear components 210 and 220. In a variation with periodic protrusions 216, the second component 220 is preferably a planetary module as shown in
The pressure control mechanism 230 functions to apply an opposing force between the first gear component 210 and the second gear component 220. The pressure control mechanism 230 in one variation is a tunable setting such that a gear system could be “tuned” to proper settings. In another variation the pressure control mechanism 230 could be a spring or pressurized system that actively applies a force connecting the two gear components 210 and 220 as shown in
One particular parallel gearing system is a planetary frictional gear system. The planetary frictional gear system described herein can be used in combination with the modular gearing system described herein, but may alternatively be implemented without a modular design.
As shown in
The system in one preferred implementation can be used as a planetary gearing system. As a planetary gearing system, an instance of the system could be used in a multi-stage system. Additionally, multiple instances with different configurations can be used in combination with a multi-stage system. As discussed above, the planetary frictional gear system can be stacked for rigidity or staged in a stacked configuration for alternative gear transmissions.
As another potential benefit compared to a cycloidal system, the system can be backdrivable. For example, when applied to the field of robotics, the system can be backdriven and physically manipulated during a motion training process. Additionally, the system can lack the eccentric properties of a cycloidal system, and thus may avoid vibrational effects.
As shown in
As compared to a strain wave gear, the system may be more efficiently manufactured at a lower cost. The parallel gearing is frictional based, and may be manufactured using a horizontal lathe without the customized fitting of pieces common in the manufacturing of a strain wave gear.
The central core 310 functions as sun gear equivalent component of the system. The central core 310 is preferably a centrally located gearing component contained within the system. The central core 310 can have a centrally positioned shaft. The shaft of the central core 310 can be used to drive the system but may alternatively be used as an output. In some variations, the central core may be held stationary.
Within the system, the central core 310 functions as the mechanical coupling between a shaft in the center axis and the planetary modules 320. The central core 310 is preferably physically coupled to a set of planetary modules at a set of coupling points. The coupling points are preferably symmetrically distributed at a fixed distance about the center of the central core 310. The coupling points may alternatively be positioned to have an asymmetrical layout. The coupling point distance is preferably sufficient to enable the planetary modules 320 to engage with the internal perimeter of the annular ring 310 and to allow the planetary modules to rotate without restrictive contact with the other planetary modules 320.
The central core 310 preferably engages with the planetary modules 320 through a rotation axel that enables the planetary modules to rotate about the coupling point. Alternatively, the central core 310 can physically couple with a planetary module through a gearing interface which is preferably a perpendicular gearing interface but could alternatively be a parallel gearing interface.
The central core 310 can be a structural component. The central core 310 could be a solid structure that extends out to the axes of the planetary modules 320. The solid structure could be a disc, a polygon (e.g., with each point corresponding to an axis of a planetary module 320), or any suitable shape. The planetary modules may rotate about the coupling point. Alternatively, the central core 310 could be a central sun gear or other mechanical system that interacts with the planetary modules 320 through a geared or frictional interaction. In one variation, the central core 310 could use a tooth gear.
The set of planetary modules 320 functions as planetary units that rotate about the central core 310. There can be any suitable number of planetary modules 320. The set of planetary modules are preferably symmetrically positioned about the central core 310, which functions to provide balanced engagement with the annular ring 330. In one implementation, there are three planetary modules evenly distributed about the center of the system. Alternatively, the set of planetary modules may not be balanced. For example, there may be a single planetary module 320 in the set. In another example, in a set of three planetary modules 320, a first planetary module 320 could be at ninety degrees from a second and third planetary module 320, and the second and third planetary modules 320 could be one hundred and eighty degrees apart. The planetary modules 320 are preferably substantially identical in component design and configuration. Preferably, the planetary modules 320 are phase synced such that each planetary module engages with the annular ring 330 in a matching state. For example, a single sub-planet engages with the annular ring in between two protrusions at the same time across multiple planetary modules 320. Alternatively, the planetary modules 320 may be phase shifted such that at least two of the planetary modules engage with the annular ring 330 in offset states. For example, a sub-planet of a first planetary module 320 can engage with the annular ring in between two protrusions at the same time two sub-planets of a second planetary module 320 engage with a protrusion on either side.
A planetary module 320 can have a variety of designs. The overall profile of the planetary module 320 is preferably configured to steadily engage with set of annular protrusions 334 during a circular rotation along the internal perimeter of the annular ring 330. In other words as the planetary module 320 rotates in a circular path concentric with the annular ring, the profile of the planetary module 320 is such that the annular protrusions 334 provide substantially constant contact without preventing rotation, and the annular protrusions 334 do not cause oscillation of the center point of the planetary module 320. As shown in
The planetary module 320 preferably includes multiple sub-planet components 324. In one preferred implementation, each of the sub-planet components is an independent circular gear that is physically coupled about a common coupling point as shown in
Alternatively, the planetary module 320 can be a solid gearing piece wherein the sub-planet components 324 are structure features (i.e., protrusions) as shown in
A planetary module 320 engages with the annular ring along the perimeter surface of the planetary module 320. The perimeter surface is preferably defined as the surface along the sides of the planetary module. In other words, the perimeter surface is the surface(s) tracing the path of the shape profile and opposing the base surface of the planetary module 320.
The perimeter surface is preferably a parallel gearing surface 322 as described above. Parallel gearing surfaces preferably acts as a frictional contract feature that promotes relative translation and/or rotation between a planetary module 320 and the annular ring 330. The parallel gearing surface includes longitudinal structures or grooves that extend around the perimeter of the planetary module 320.
The parallel gearing surface 322 preferably physically couples with the parallel gearing surface 332 of the annular ring 330. In the independent gear variation, each gear can have parallel gearing 322. In the single unit planetary module 320, the parallel gearing can trace around the perimeter surface. The parallel gearing is preferably located where contact will be made, but areas that will not make contact may not have the parallel gearing 322. For example, a single unit planetary module 320 may have a form where the parallel gearing surface is not continuous around the entire perimeter because of interactions with the protrusions 334.
The annular ring 330 is the outer ring that circumscribes and/or contains the other components. The annular ring 330 defines an internal cavity such that the annular ring 330 has an internal surface. The planetary modules 320 preferably physically couples and interacts with the annular ring 330 at the internal surface. The internal perimeter surface of the annular ring 330 preferably includes complementary gearing to the gearing used in the planetary module 320. Preferably, the gearing is a parallel gearing surface 332 that follows the internal perimeter surface of the annular ring 330.
The annular ring 330 additionally includes a set of annular protrusions 334, which function as structural features. The annular protrusions 334 preferably form a macro cycloidal gear profile, where the cycloidal “tooth” profile is based on the size of the sub-planet components 324 of the planetary module 320. The annular protrusions 334 can mitigate the occurrence of backlash. A planetary module 330 will rotate about the annular protrusions 334, and potential slippage at the parallel gearing surface may be counteracted by the physical coupling of the planetary module with the annular protrusions 334. The primary mechanical coupling occurs at the gearing surface of the annular ring 330 and the planetary modules 320, but the annular protrusions 334 can act as a secondary mechanical coupling that can prevent gross gear “slippage”. The annular protrusions 334 are preferably structural elements that extend out from the body of the annular ring (i.e., inwards toward the defined center point of the annular ring 330). Alternatively, pegs or other forms may be used to achieve similar mechanical interactions between the annular ring and the planetary modules 320. The annular protrusions 334 are preferably regularly spaced defined around a defined circle. The depth, curve profile, spacing, and other physical characteristics are preferably configured such that functional contact can be established with the planetary modules 320 during operation. a sinusoidal undulating profile may be used.
As shown in
The assembly of the system preferably sets the planetary modules 320 at a displacement from the internal perimeter of the annular ring 330 such that a satisfactory level of surface pressure is established. In one variation, the planetary modules 320 are statically set. However, the system may include a pressure control mechanism 340, which can function to make the fitting of the planetary modules 320 adjustable.
The pressure control mechanism 340 in one instance may allow the torque properties of the system to be adjusted by adjusting the surface pressure between the parallel gearing of the annular ring 330 and the planetary modules 320. For example, the planetary modules may be set to more tightly press against the internal perimeter of the annular ring 330 for higher torque applications.
The pressure control mechanism 340 in another instance may function to enable maintenance to be applied to the system after components have worn down. As opposed to other systems where the wearing of teeth cannot be easily remedied, the use of parallel gearing enables the pressure to recalibrate to restore the system to desired operating parameters.
In one variation, the pressure control mechanism 340 includes a planetary module adjustment system as shown in
In one variation, the pressure control mechanism 340 includes a central core adjustment system which functions to vary the coupling point between a planetary module 320 and the central core 310. For example, the mounting point of the planetary module to the central core 310 could be variable. In one variation, the coupling point could be adjusted along a line defined that radially extends from the center of the central core 310 as shown in
The pressure control mechanism 340 could be a maintenance or configuration feature, but in some variations, the pressure control mechanism 340 could be dynamically controlled. A dynamic pressure control mechanism 340 could be used to change the pressure to operate the system in different modes. For example, a system could normally operate with a default torque performance property, but during particular times when high amounts of torque are desired, the pressure control mechanism 340 could switch the system to a high torque mode by increasing the surface pressure. In some implementations, this can function to enable a pressure control mechanism 340 to transition a system from operating in high and low torque modes, where a low torque mode may have less wear on the system, thereby can extend the life of the system.
The pressure control mechanism 340 or an alternative element of the system could additionally measure the pressure setting of the system such that the state of system could be observed. The pressure sensing could additionally be used in combination with observing usage of the system to an effective lifetime estimation based on the amount of usage and the pressure settings during usage. The pressure control mechanism 340 could include integrated sensors and control system such that the settings of the pressure control mechanism 340 can be monitored and controlled by an external system.
The system could be used as an alternative planetary gearing system. Various gear ratios may be achieved depending which components are used as the output, input, and held stationary.
In an alternative embodiment shown in
In the flex spline embodiment, the set of planetary modules 320 and the annular ring 330 do not physically engage directly. Instead, the planetary modules 320 engage with the annular ring 330 with the flex spline 350 as an intermediary element.
The flex spline 350 includes a flexible portion that circumscribes the set of planetary modules 320 and the central core 310. In one implementation, the flex spline 350 can include a defined concave cavity like a cup. The base of the flex spline 350 can be a rigid structure. The base could be attached to a shaft or mechanically coupled to some other component. The walls defining the concave cavity are preferably flexible and can be deformed. The thin walls of the flex spline 350 are the portions that are used in the physical interaction of the system. The length of the flex spline 350 is preferably less than the length of the internal perimeter of the annular ring 330 as shown in
The flex spline 350 in one variation includes a parallel gearing surface pattern such that when fully engaged, a planetary module 320, the flex spline 350 and the annular ring 330 have mating profiles as shown in
The components of the system can be made of any suitable material. The parallel gearing can be machined using a horizontal lathe, but the parallel gearing and other components may be made through any suitable manufacturing technique.
The components of the system can similarly be designed and implemented at a variety of scales. The system can be customized to satisfy a wide variety of torque performance properties and support different gear ratios.
An inter-stack brace may be used in connecting multiple planetary frictional gear systems, which as described, can be for mechanical properties or for staging and changing gear ratios. Instances of the system can be used in multiple stage gearing solutions. A set of planetary gear system variations, a set of flex spline system variations, and/or any suitable gear system may be used in combination. In one exemplary implementation, a planetary gear system variation with a five to one gear ratio could be combined with a flex spline system variation with a gear ratio of two hundred to one. The resulting gearing ratio would be one thousand to one.
As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the embodiments of the invention without departing from the scope of this invention as defined in the following claims.
This Application claims the benefit of U.S. Provisional Application No. 62/319,222, filed on 6-Apr.-2016, which is incorporated in its entirety by this reference.
Number | Date | Country | |
---|---|---|---|
62319222 | Apr 2016 | US |