Patent Publication Number: US-2022221041-A1

Title: Gearbox assembly for hobby robotics

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 63/136,925, filed Jan. 13, 2021, the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Hobby robotic systems often include a variety of structural and motion components coupled to one another. In the field of hobby robotics, it is common to assemble these various structural and motion components to create robotic systems. Components may include, for example, motors, coupling mechanisms, actuators, sensors, gear systems, and the like. Different components may be assembled in various configurations depending on the desired operation of the system by a user. 
     SUMMARY 
     A motor gearbox system includes a motor. The system further includes a mount configured to couple to the motor. The system also includes a housing configured to couple to the mount, and a coupler configured to couple to the housing, the coupler having at least one mounting feature configured to couple to a component. The system further includes a gear system operably coupled to the motor and configured to be disposed, at least in part, within a gearbox formed by the coupled mount, housing and coupler. The system includes an output shaft operably coupled to the gear system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an example motor and gearbox assembly with which embodiments of the present invention are particularly applicable. 
         FIG. 2  is a sectional view showing an example motor gearbox assembly with which embodiments of the present invention are particularly applicable. 
         FIG. 3  is a sectional view showing another example motor gearbox assembly with which embodiments of the present invention are particularly applicable. 
         FIG. 4  is a sectional perspective view showing an example motor gearbox assembly in accordance with an embodiment of the present invention. 
         FIG. 5  is a sectional view showing an example planetary gear assembly in accordance with an embodiment of the present invention. 
         FIG. 6  is an exploded perspective view showing an example motor gearbox assembly with which embodiments of the present invention are particularly applicable. 
         FIG. 7  is a perspective view showing an example output shaft in accordance with an embodiment of the present invention. 
         FIG. 8  is a perspective view showing an example output shaft assembly in accordance with an embodiment of the present invention. 
         FIG. 9  is a perspective sectional view showing an example gearbox housing assembly in accordance with an embodiment of the present invention. 
         FIG. 10  is a perspective sectional view showing an example gearbox housing assembly in accordance with an embodiment of the present invention. 
         FIG. 11  is a perspective view showing an example coupler in accordance with an embodiment of the present invention. 
         FIG. 12  is a bottom perspective view showing an example coupler in accordance with an embodiment of the present invention. 
         FIG. 13  is a perspective view showing an example mount in accordance with an embodiment of the present invention. 
         FIG. 14  is a perspective view showing an example the gearbox housing in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     In the field of hobby robotics, it is common to assemble various structural and motion components to create robotic systems. In such systems, motion components may include a rotational actuator with an output shaft, such as an electric motor. Such motors can lack the torque required for certain operations and in such situations a gearbox can be provided to increase the torque provided by the motor or other actuator. However, gearboxes can be overly cumbersome and increase the size of the system. Gearboxes can also limit the ways in which the motor/gearbox assembly can couple to other components. 
     Accordingly, this disclosure illustrates example gearbox assemblies that includes features to reduce the size of the gearbox assembly while retaining its functionality. In one example herein, the gearbox is substantially no larger than the motor in two dimensions and only increases the size the motor in a third direction (e.g., the height of the motor). To reduce the size of the gearbox, the mounting plate that typically mounts to the motor may be strategically placed. In one example, the plate is completely covered by a ring gear of the gearbox. In this way, the gearbox becomes more compact so that it can fit in space-limited assemblies. 
     Additionally, as further described below with respect to  FIG. 5 , the ring gear of the planetary gearbox has similar geometry on each end. The similar geometry allows the coupler (also referred to as a face) of the gearbox to be bolted to both ends, replacing the motor. Doing so would allow the construction of a reduction gearbox with an input shaft that would replace a motor. In one embodiment, the ring gear has a uniform and matching geometry on each end about the gearbox housing. 
     In one example, the gearbox output shaft bearings are sunken into the housing of the gearbox. The outer bearing that holds the output shaft is sunken into the face of the gearbox to allow components to more closely locate on a shelf between a thicker portion of the output shaft (that is disposed within the outer bearing), and an exposed smaller shaft portion. This recessed/sunken bearing makes room for items, such as thrust bearings, ball bearings, collars, pinion gears, etc. in space-limited assemblies. Additionally, the open space created about the output shaft allows collars and rotating components, with a diameter smaller than the open space to be mounted and/or coupled in the appropriate location. In some examples, diameter clearance cuts on the face allows for nearby bearings, collars, shafts and other rotating components to coexist. The clearance cuts may be, for example, 14 mm (millimeter) diameter clearance cuts. 
     Since a gearbox receives a shaft of the motor and also has an output shaft of its own, the output shaft of the gearbox can include additional features that are not present on the motor output shaft. For example, the output shaft of the gearbox can have a profile that is a blend of a hexagon feature (to create a positive drive with a mating part of a profile-matched bore), and a round feature (to allow parts with an appropriate diameter bore to fit properly). In one example and further described below, the hexagon is a 7 mm flat to flat hexagon and the round has an 8 mm diameter. In some instances, the length of the shaft is chosen to protrude the right amount through the structure that the motor is attached to, such that the couplers and other mating components can fasten onto the shaft without interference with the structural walls or other pieces that coexist within the assembly. In one embodiment, this distance is 23.5 mm. However, in other embodiments, the shaft length may be adjusted based on the structural composition of the assembly. 
     In some examples, a threaded aperture is provided on the end of the shaft. In one example, the threaded aperture is a M4 hole. Further, the gearbox can have additional structural mounting components that allow the motor to be coupled to the items in other ways than standard motor mounts. For example, the gearbox coupler can have 8 mm, 16 mm and/or 24 mm mounting patterns. The 16 mm threaded hole pattern, for example, allows for the mating of the gear motor to any part that has through-holes corresponding to the 16 mm pattern. In one embodiment, the 24 mm threaded hole pattern is sunken into the face such that an object, such as a flat beam, can attach and remain on the grid pattern. For instance, the 24 mm threaded hole pattern may be sunken in by 4 mm. 
       FIG. 1  is a perspective view showing an example motor and gearbox assembly with which embodiments of the present invention are particularly applicable. Assembly  100  includes motor  102 , gearbox  104 , coupler  106  and output shaft  108 . Motor  102 , as shown, is an electrically driven motor. However, in other examples, motor  102  can be replaced with any other motion component that has an output shaft that can be received by the gearbox  104 . Gearbox  104  receives an output shaft of motor  102  and changes the driving ratio of the output shaft of motor  102  to output shaft  108  of gearbox  104 . Gearbox software can also include coupler  106  that has various mounting components that allow assembly  102  to be coupled to another object. For example, the gearbox coupler can have 8 mm, 16 mm and/or 24 mm mounting patterns, which allow for the mating of the gear motor to any part that has through-holes corresponding to the pattern. Output shaft  108  includes various features that couple to an external component. For example, as illustrated in  FIG. 1 , a threaded aperture is provided on the end of the shaft to allow for a unique way to attach components to output shaft  108 . Additionally, as illustrated, output shaft  108  may have a hexagonal shape to create a positive drive with a mating part with a profile-matched bore. Further, output shaft  108  may also include a round shape having a set diameter to allow parts with a corresponding diameter to fit properly. As shown gearbox  104 , coupler  106  and output shaft  108  can comprise a metal material such as aluminum and/or steel. In some examples, output shaft  108  comprises a stainless-steel material, and coupler  106  and gearbox  104  comprise aluminum. 
       FIG. 2  is a sectional view showing an example motor gearbox assembly with which embodiments of the present invention are particularly applicable. As shown, motor  102  is coupled to mount  126  by fasteners  130 , which is seen more clearly in  FIG. 3 . Additionally, mount  126  is coupled to housing  116  by fasteners  128 , and coupler  124  is coupled to housing  116  by fasteners  128 . As illustrated, fasteners  128  and  130  are threaded fasteners. Output shaft  108  is disposed within coupler  124  via carrier  118 . The output shaft is disposed within coupler  124  at a length strategically chosen such that the correct length of output shaft  108  protrudes through a desired structure that motor  102  is attached to. 
     Mount  126  includes through-holes that allow fasteners  130  to pass-through and couple to motor  102 . Additionally, housing  116  has through-holes that allow fasteners  128  to pass-through and couple to either mount  126  or coupler  124 . In some examples, housing  116  is reversible and can be reversed such that the apertures that are aligned with coupler  124  can be switched with the apertures that are aligned with mount  126 . Motor  102  has a motor shaft  110  that is coupled to a gear  112 . As shown, gear  112  is a sun gear in a planetary gear system. Gear  112  engages planetary gears  114  which further engage the ring gear of housing  116 , described further in  FIG. 5 . 
     As shown, planetary gears  114  are coupled to carrier  118  by pins  120 . In operation, as the motor shaft  110  coupled to gear  112  rotates, it drives gears  114 , which are rotated about pins  120  and motor shaft  110 . Thus, as gears  112  rotates, carrier  118  rotates at a slower pace. As shown, carrier  118  is coupled to the output shaft  108  and is held within coupler  124  by bearings  122 . Bearings  122  reduce the friction between output shaft  108  and coupler  124 . Bearings  122  can also help reduce sideloading on motor  102 . Output shaft  108  is prevented from being pushed into the gearbox by snap ring  109 . Specifically, a second portion of output shaft  108  within the bearings is of a larger diameter than the first portion, which allows snap ring  109  to couple to output shaft  108  and thus constrain output shaft  108  from being pushed into the gearbox. 
       FIG. 3  is a sectional view showing another example motor gearbox assembly with which embodiments of the present invention are particularly applicable.  FIG. 3  bear some similarities to  FIG. 2 , and like components are numbered similarly. In this view, a narrow portion of coupler  124  can be seen. The narrow portion of coupler  124  is defined by flat surfaces, such as flat surfaces  302  shown below with respect to  FIG. 11 . In some examples, the flat surfaces  302  are spaced such that an accessory or tool can interact with coupler  124 . Further, fasteners  130  are also more clearly illustrated, which serve to couple motor  102  to mount  126 . Additionally, the arrangement of gears  112  in gear  114  can be seen. As shown, there are three planetary gears, however, in other examples, there may be fewer or additional planetary gears  114 . Finally, mounting plate  132  is shown, which is configured to mount to motor  102 . As illustrated, mounting plate  132  is strategically placed to be completely covered by gears  112  of the gearbox. In this way, the gearbox becomes more compact so that it can fit in space-limited assembles. Thus, the size of the gearbox is reduced. 
       FIG. 4  is a sectional perspective view showing an example motor gearbox assembly in accordance with an embodiment of the present invention.  FIG. 4  bears some similarities to  FIGS. 2-3 , and like components are numbered accordingly. In this view, some contours of the components are more easily seen. For example, as illustrated, output shaft  108  is disposed within coupler  124  via carrier  118 . The output shaft is disposed within coupler  124  at a length strategically chosen such that the correct length of output shaft  108  protrudes through a desired structure that motor  102  is attached to. As illustrated, the second lower portion of output shaft  108  is of a larger diameter than the first portion, which allows a snap ring to couple to output shaft  108  and thus constrain it from being pushed further into the gearbox. Additionally, a threaded aperture disposed at an end of output shaft  108  is more visibly shown. In one example, the threaded aperture is a M4 hole. 
       FIG. 5  is a sectional view showing an example planetary gear assembly in accordance with an embodiment of the present invention. As shown, there are three planetary gears  114  and a singular sun gear  112  within a ring gear of housing  116 . In other examples, there may be additional gears or different arrangements of the gears. For instance, multiple planetary gear arrangements are stacked on one another to further alter the drive ratio between motor shaft  110  and output shaft  108 . In operation, gear  112  engages planetary gears  114  which further engage the ring gear of housing  116 . As illustrated, the ring gear of the planetary gearbox has a similar geometry on each end. The similar geometry allows the coupler to be bolted to both ends, replacing the motor. In doing so, this allows the construction of a reduction gearbox with an input shaft that would replace a motor. In one embodiment, the ring gear has a uniform and matching geometry on each end about housing  116 . 
       FIG. 6  is an exploded perspective view showing an example motor gearbox assembly with which embodiments of the present invention are particularly applicable.  FIG. 6  bears some similarities to  FIG. 2 , and like components are numbered accordingly. As illustrated, mounting plate  132  is more clearly shown to be a ring shape. Upon assembly, mounting plate  132  is strategically placed to be completely covered by gears  112  of the gearbox. Additionally, shown more clearly in this figure are bearings  122 , snap ring  109 , pins  115 , gears  114 , and shaft  110 . When shaft  110  and gears  112  rotate, the engagement drives gear  114 , as described in more detail below in  FIG. 8 . Finally, fasteners  128  and  130  are more visibly shown. As shown, fasteners  128  and  130  are threaded fasteners. 
       FIG. 7  is a perspective view showing an example output shaft in accordance with an embodiment of the present invention. As shown, output shaft  108  includes shaft  202 , snap ring groove  204 , hex portion  206 , threaded aperture  208 , carrier  210  and planetary apertures  212 . Shaft  202  allows output shaft  108  to couple to a bearing to reduce friction between output shaft  108  and another component. In some examples, shaft  202  is 10 mm in diameter and is received by a ball bearing. Output shaft  202  illustratively includes groove  204  that allows for the coupling of a snap ring onto output shaft  108 . As described above, the snap ring prevents or reduces the longitudinal movement of the output shaft  108 . Hex portion  206  includes hexagonal features such that output shaft  108  can be coupled to another component to provide rotational movement to the component. In this way, a positive drive is created with a mating part of a profile-matched bore. Hex portion  206  can also include round features such that the output shaft can be received in a (circular or otherwise) aperture. In some examples, hex portion  206  has a 7 mm flat to flat size and an 8 mm corner to corner size. This configuration allows portion  206  to be received by an 8 mm round aperture, or couple to a 7 mm hex component. Additionally, aperture  208  allows for the output shaft to be coupled to another component. In some examples, threaded aperture  208  is a 4 mm aperture. Output shaft  108  is driven by planetary gears that couple to the output shaft  108  through planetary apertures  212  located on planetary carrier  210 . As shown, there are three planetary apertures  212 , however, in other examples there may be a different amount of planetary apertures  212 . 
       FIG. 8  is a perspective view showing an example output shaft assembly in accordance with an embodiment of the present invention. As shown in this figure are bearings  122 , snap ring  109 , pins  115 , gears  114 , shaft  110  and gear  112 . When shaft  110  and gear  112  rotate, the engagement of gear  112  and gear  114  drives gear  114 . Gears  114 , when rotated, transfer energy to shaft  118  through pins  115 . In other words, in operation, as shaft  110  coupled to gear  112  rotates, it drives gears  114 , which are rotated about pins  115  and shaft  110 . Thus, as gears  112  rotates, the carrier (such as carrier  118 ) rotates at a slower pace. 
       FIG. 9  and  FIG. 10  illustrate a perspective sectional view showing an example gearbox housing assembly in accordance with an embodiment of the present invention.  FIG. 10  is a perspective sectional view of a gearbox housing assembly taken from a plane perpendicular to the plane of sectional plane of  FIG. 9 . As shown, mount  126  is coupled to housing  116  and housing  116  is coupled to coupler  124 . In other examples, coupler  124  can be interchangeable such that either part fits on either side of housing  116 . 
       FIG. 11  and  FIG. 12  are perspective views showing an example coupler in accordance with an embodiment of the present invention. Coupler  124  includes a variety of features that allow for coupling of coupler  124  to the motor/gearbox assembly and to another component in a robotic system. Mounting apertures  306  include threaded apertures that couple to a corresponding hole pattern of another component. Flat surfaces  302  are spaced such that an accessory or tool can interact with coupler  124 , and are configured to couple coupler  124  to a component having one or more corresponding flat surfaces. In one example, flat surfaces  302  are spaced apart 24 mm. In this way, the open space created by flat surfaces  302  allows components with a diameter of less than 24 mm to be mounted to an aperture only 24 mm away from the location of the gear motor. 
     Aperture  310  can include various features for various functions. Aperture  310  can be sized to accommodate ball bearings. Additionally, aperture  310  can be sized to allow a part to rotate without contacting the raised portions containing apertures  306 . Channel  304  can be sized to allow the mounting of components at least partially within channel  304 . 
       FIG. 13  is a perspective view showing an example mount in accordance with an embodiment of the present invention. As noted earlier, mount  126  couples a gearbox to a motor  102 . This mounting can be accomplished through the use of mounting apertures  404 . As shown, mounting apertures  404  are set within a recess  406  such that the heads of the fasteners that fit in mounting apertures  404  do not contact components that are above mount  126 . In one embodiment, mounting apertures  404  are threaded apertures. Additionally, threaded apertures  402 , as shown earlier, are provided to couple mount  126  to housing  116 . 
       FIG. 14  is a perspective view showing an example the gearbox housing in accordance with an embodiment of the present invention. Housing  116  includes wall  502 , gear portion  504 , surfaces  506  and mounting apertures  508 . Wall  502  can be shaped and sized to fit within a footprint of a motor such that the gearbox increases the size of a motor/gearbox assembly in only one dimension. A plurality of mounting apertures  508  are disposed within wall  502 . These mounting apertures  508  are used to couple housing  116  to other components, such as mount  126  and coupler  124 . In some examples, housing  116  is symmetrical such that mount  126  and coupler  124  can be mounted on either side of housing  116 . This symmetry may also allow for the stacking of multiple gearboxes on top one another to further modify the gear ratio of the overall drive system. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.