Patent Publication Number: US-2023137602-A1

Title: Counter Rotating Gear Case for a Drive Unit

Description:
RELATED APPLICATIONS 
     This application is related and claims priority to U.S. Provisional Patent Application No. 63/274,772, entitled “Counter Rotating Gear Case for Marine Drive Unit” filed on Nov. 2, 2021, the application of which is incorporate herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The subject matter of the present invention relates generally to a counter rotating gear case, and more particularly to a counter rotating gear case for converting a standard single prop drive unit to a double prop counter rotating drive unit. 
     BACKGROUND 
     Typical motors, such as trolling motors for boats, use a single (one) prop design. However, the single prop design can be inefficient. Since, trolling motors are typically battery powered, these inefficiencies can lead to reduced running time as the battery life may be drained quicker. This can be especially true in certain fishing conditions, such as in areas with higher aquatic vegetation, strong currents, rough water, chasing fast schools of fish, etc. 
     Additionally, anglers may want to change or customize their prop type/design based on certain types of fishing and/or conditions. For example, a bass angler may need a prop design that can more easily cut through aquatic vegetation (grass, lily pads, etc.), whereas an angler fishing inshore flats might need blades designed for higher speed for chasing fast larger fish. A typical trolling motor prop is not easily changed out, and may require differing drive units to accommodate the differing prop designs. 
     What is needed is an improved system and method of increasing the efficiencies of these types of motors, as well, as making it easier to modify such motors to customize to an anglers preference/type of fishing. 
     SUMMARY 
     In one embodiment, a counter rotating gear case is provided. The counter rotating gear case may include a forward gear assembly; an aft gear assembly; a pinion gear assembly; a spool adapter having a first portion and a second portion, wherein the forward gear assembly, the aft gear assembly, and pinion gear assembly may be supported on the second portion of the spool adapter; and wherein, the pinion gear assembly may be disposed between the forward gear assembly and the aft gear assembly, and wherein the pinion gear assembly may be operatively engaged with both the forward gear assembly and the aft gear assembly, such that rotation of one of the forward gear assembly or the aft gear assembly in one direction causes rotation of the other of the forward gear assembly or the aft gear assembly in a second direction opposite that of the first direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Having thus described the subject matter of the present invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG.  1    illustrates a cross-sectional view of an example counter rotating gear case, in accordance with an embodiment of the invention; 
         FIG.  2    illustrates a view of the example counter rotating gear case of  FIG.  1   , in accordance with an embodiment of the invention; 
         FIG.  3    illustrates a partial exploded view of the example counter rotating gear case of  FIG.  1   , in accordance with an embodiment of the invention; 
         FIG.  4    illustrates a side perspective view of an assembled example counter rotating gear case with props attached, in accordance with an embodiment of the invention; 
         FIG.  5    illustrates a side view of a spool adapter, in accordance with an embodiment of the invention; 
         FIG.  6    illustrates a front view of a forward drive gear hub, in accordance with an embodiment of the invention; 
         FIG.  7    illustrates a front view of a forward drive gear, in accordance with an embodiment of the invention; 
         FIG.  8    illustrates a view of components of a forward gear thrust bearing, in accordance with an embodiment of the invention; 
         FIG.  9    illustrates a perspective view of a spool adapter assembled with a forward drive gear hub, in accordance with an embodiment of the invention; 
         FIG.  10    illustrates a front view of a forward drive gear installed in a housing, in accordance with an embodiment of the invention; 
         FIG.  11    illustrates a side cross-sectional view of an aft drive gear hub, in accordance with an embodiment of the invention; 
         FIG.  12    illustrates a side view of an aft gear assembly, in accordance with an embodiment of the invention; 
         FIG.  13    illustrates a view of components of an aft gear thrust bearing, in accordance with an embodiment of the invention; 
         FIG.  14    illustrates a side cross-sectional view of a pinion spool spacer, in accordance with an embodiment of the invention; 
         FIG.  15    illustrates a side view of a pinion spool spacer with a pinion gear installed, in accordance with an embodiment of the invention; 
         FIG.  16    illustrates a partial side cross-sectional view of a counter rotating gear assembly, in accordance with an embodiment of the invention; 
         FIG.  17    illustrates a side view of an assembled gear housing, in accordance with an embodiment of the invention; 
         FIG.  18    illustrates a perspective view of an assembled gear housing, in accordance with an embodiment of the invention; 
         FIG.  19    illustrates a side view of an assembled gear housing with a forward drive gear hub and spool adapter installed, in accordance with an embodiment of the invention; 
         FIG.  20    illustrates a perspective view of counter rotating gear case disassembled from a host drive unit, in accordance with an embodiment of the invention; 
         FIG.  21    illustrates a side view of counter rotating gear case partially assembled with a host drive unit, in accordance with an embodiment of the invention; 
         FIG.  22    illustrates a perspective view of an assembled counter rotating gear case with counter rotating props, in accordance with an embodiment of the invention; and 
         FIG.  23    illustrates a side view of an assembled counter rotating gear case with counter rotating props, in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The subject matter of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the subject matter of the present invention are shown. Like numbers refer to like elements throughout. The subject matter of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the subject matter of the present invention set forth herein will come to mind to one skilled in the art to which the subject matter of the present invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated Drawings. Therefore, it is to be understood that the subject matter of the present invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. 
     In some embodiments, the subject matter of the invention provides a counter rotating gear case to apply to a drive unit, such as a marine trolling motor. However, the counter rotating gear case may be used with a drive unit for other marine/non-marine propulsion system including gas/diesel, electric, etc. 
     In some embodiments, the subject matter of the invention provides a counter rotating gear case that may be adaptable to any type of drive system, such as, pin drive, square drive, or spline drive, and may be used for drive units of mud motors, trolling motors, bow and stern thrusters, and the like. 
     In some embodiments, the subject matter of the invention may provide a self-contained counter rotating gear case, for example, for a marine drive unit, which requires no modification to the original marine drive unit, and converts the original single prop drive unit to a double prop counter rotating drive unit. 
     Referring now to  FIGS.  1 - 23   , a counter rotating gear case  100  for a host drive unit  10  is provided. The counter rotating gear case  100  may include a housing  103 , spool adapter  105 , forward gear assembly  107 , an aft gear assembly  109 , a pinion gear  111 , a pinion spool spacer  113 . In one example, spool adapter  105 , forward gear assembly  107 , aft gear assembly  109 , pinion gear  111 , pinion spool spacer  113  may be configured together in an assembled state in housing  103 . The counter rotating gear case  100  may further include one or more of one or more inner seals  121 , and one or more outer seals  123 , a prop nut/bolt  115 , set screw  119 , and drain plug  117 . 
     Spool adapter  105  may be generally tubular in shape, and may include a first portion  125  and a second portion  127 . In one example, the first portion  125  of the spool adapter  105  may have a larger diameter than that of the second portion  127 . Spool adapter  105  may engage the counter rotating gear case  100  with, for example, a host drive unit  10 . In one non-limiting example, the host drive unit  10  may be a trolling motor drive unit. The size and specifications of pool adapter  105 , may change depending on the type/brand of host drive unit  10 . 
     Spool adapter  105 , in one example, may slide on the prop drive shaft  15  of the host drive unit  10 . The first portion  125  of the spool adapter  105  may engage with a hub  25  of the host drive unit  10 . In one example, an inner diameter of the first portion  125  of the spool adapter  105  is sized to closely fit about an outside diameter of the hub  25  thereby anchoring the spool adapter  105  (and thereby the entire counter rotating gear case  100 ) to the host drive unit  10  in stable manner. Set screw  119  may be tightened, as needed, to further secure the spool adapter  105  in place. 
     Spool adapter  105  may further support the forward drive gear assembly  107  and the aft drive gear assembly  109 . The forward drive gear assembly  107  may include drive gear thrust bearings  147 , a forward drive gear  149 , and a forward drive gear hub  151 . The aft drive gear assembly  109  may include drive gear thrust bearings  147 , an aft drive gear  153 , and an aft drive gear hub  155 . Each set of the drive gear thrust bearings  147  may include, for example, inner and outer flat races  173  and a bearings  175 . Bearings  175  may be of any suitable type (or types) of bearing, including but not limited to ball, needle, needle, ball, or other type bearing. 
     In one embodiment, a first set of drive gear thrust bearings  147   a  may be inserted on a neck portion of the second portion  127  of spool adapter  105 , and positioned generally where the neck of second portion  127  and first portion  125  of the spool adapter  105  meet. In one example, the first set of gear thrust bearings  147   a  may rest against a distal most portion of the first portion  125  of the spool adapter  105 . Forward drive gear hub  151  may also be inserted on the neck of second portion  127  of spool adapter  105 , such that the first set of gear thrust bearings  147   a  is sandwiched between the distal portion of the first portion  125  of the spool adapter  105  and a first face of the forward drive gear hub  151 , thereby allowing the forward drive gear hub  151  to rotate about the spool adapter  105 , which is stationary. Forward drive gear  149  may be attached to a second face of the forward drive gear hub  151 , such that rotation of the forward drive gear  149  causes the forward drive gear hub  151  to rotate in the same rotational direction as that of the forward drive gear  149 . A second set of gear thrust bearings  147   b  may be inserted on the spool adapter  105 , and positioned immediately adjacent to a side of the forward drive gear  149  opposite that of the side attached to the forward drive gear hub  151 . Forward drive gear hub  151  may include flange  157 , whereby a forward prop  159  may be attached thereto, such that rotation of the forward drive gear hub  151  causes the forward prop  159  to rotate in the same rotational direction as that of the forward drive gear hub  151 . An outer seal  123  may be disposed between an outer surface of the spool adapter and an inward facing surface of the forward gear drive hub. The outer seal  123 , in one example, may function to keep water and debris (mud, etc.) from getting into the counter rotating gear case  100 , and/or to keep gear oil/lubricant within the counter rotating gear case  100 . The outer seal  123 , may be made of any suitable material, such as, but not limited to, rubber, silicone, or any other suitable material. 
     The aft drive gear hub  155  may be generally tubular in shape, and may include a first portion  161  and a second portion  163 , wherein the first portion  161  of the aft drive gear hub  155  may have a smaller diameter than that of the second portion  163 . In one example, the first portion  161  of the aft drive gear hub  155  is sized such that it may be inserted into an interior region of the second portion  127  of the spool adapter  105 , and extends into the first portion  125  of the spool adapter  105 . An end most portion of the first portion  161  of the aft drive gear hub  155  may have a one or more cut out regions  165 . The one or more cut out regions  165  are capable of receiving a horizontal profile of a drive/shear pin  20  of the drive shaft  15  of the host drive unit  10 , such that when received within the one or more cut out regions  165 , rotation of the drive/shear pin  20  by the drive shaft  15  of the host drive unit  10 , causes the aft drive gear hub  155  to rotate in the same rotational direction as that of the drive shaft  15 . An inner seal  121  may be disposed between an outer surface of the first portion  161  of the aft drive gear hub  155  and an inner surface of the of the spool adapter  105  within which the first portion  161  of the aft drive gear hub  155  is inserted in. The inner seal  121 , in one example, may function to keep water and debris (mud, etc.) from getting into the interior region of the counter rotating gear case  100 , and/or to also keep gear oil/lubricant within the interior region of the counter rotating gear case  100 . The inner seal  121  may be made of any suitable material, such as, but not limited to, rubber, silicone, or any other suitable material. The first portion  161  of the aft drive gear hub  155  may further include a groove  166 , for example for a snap ring (not shown) or the like. 
     The aft drive gear  153  may be attached to a first face of the aft drive gear hub  155 , such that rotation of the aft drive gear hub  155  causes the aft drive gear  153  to rotate in the same rotational direction as that of the aft drive gear hub  155 . A third set of gear thrust bearings  147   c  may be inserted on the aft drive gear hub  155  and positioned immediately adjacent to a side of the aft drive gear  153  opposite that of the side attached to the aft drive gear hub  155 . An aft prop  169  may be attached to an outward facing surface  167  of the second portion  163  of the aft drive gear hub  155 , such that rotation of the aft drive gear hub  155  causes the aft prop  169  to rotate in the same rotational direction as that of the aft drive gear hub  155 . 
     The counter rotating gear case  100  may further include a pinion gear  111  and pinion spool spacer  113 . Pinion gear  111  and pinion spool spacer  113  function to enable the counter rotation action of the forward prop  159  and aft prop relative to one another. In one example, pinion spool spacer  113  is installed on the second portion  127  of the spool adapter  105 , and positioned between the second set of gear thrust bearings  147   b  and third set of gear thrust bearings  147   c,  such that forward drive gear  149  and aft drive gear  153  are spaced apart from one another by the width of pinion spool spacer  113 , and wherein the second set of gear thrust bearings  147   b  and third set of gear thrust bearings  147   c  allow the forward drive gear  149  and aft drive gear  153  to rotate against the pinion spool spacer  113 , which remains stationary. 
     In one example, pinion gear  111  is installed in the counter rotating gear case  100 , by for example a pinion bolt  171 , or other suitable mechanism. Pinion gear  111  is positioned between the forward drive gear  149  and the aft drive gear  153 , such that the gear teeth of pinion gear  111  engage simultaneously with the gear teeth of both the forward drive gear  149  and the aft drive gear  153 . 
     In one example, when the counter rotating gear case  100  is installed on the drive shaft  15  of the host drive unit  10 . The drive shaft  15  passes through a center portion of the counter rotating gear case  100 , i.e., through spool adapter  105  and a portion of the aft drive gear hub  155 , thus allowing the counter rotating gear case  100  to reach down to the drive/shear pin  20  of the host drive unit  10 . The drive pin  20  engages with the one or more cut out regions  165  of the aft drive gear hub  155  and acts to rotate the aft drive gear hub  155  as the drive shaft  15  of the host drive unit  10  rotates, and in the same rotational direction. As the aft drive gear hub  155  rotates in a first rotational direction, for example, counterclockwise, the aft drive gear  153 , attached to the aft drive gear hub  155 , also rotates in the same first rotational direction. The rotation of the aft drive gear  153 , which is engaged with the pinion gear  111 , reacts against the pinion gear  111  causing the pinion gear  111  to rotate. Rotation of the pinion gear  111 , which is also engaged with the forward drive gear  149 , causes forward drive gear hub  151 , attached to the forward drive gear  149 , to turn in a second rotational direction, i.e., opposite that of the first rotational direction, for example, clockwise. As a result, the forward prop  159 , engaged with the forward drive gear hub  151 , and the aft prop  169 , engaged with the aft drive gear hub  155 , counter rotate relative to one another. 
     The counter rotating gear case  100 , may further include a drain plug  117 . The drain plug  117 , may be positioned on an underside portion of the housing  103 . In one example, drain plug  117  may be removed to fill or drain gear oil from the interior of counter rotating gear case  100 . The drain plug  117 , may further include a gasket (not shown) to seal the drain plug  117  when installed. 
     To install the counter rotating gear case  100  to the host drive unit  10 , the original propeller, if installed, may be removed from the host drive unit  10 , and counter rotating gear case  100  is slide onto the drive shaft  15  of the host drive unit  10 . Once seated in place on the drive shaft  15 , with the one or more cut out regions  165  of the aft drive gear hub  155  engaged with the drive pin  20 , the set screw  119  of the counter rotating gear case  100  may be tightened and the prop nut  115  installed to secure the counter rotating gear case  100  to the drive shaft  15  of the host drive unit  10 . Different props or prop blades, designed for differing conditions or preferences, may be installed. 
     To remove the counter rotating gear case  100  from the host drive unit  10 , the prop nut  115  may be removed and the set screw  119  on the counter rotating gear case  100  loosened. Once the prop nut  115  is removed and the set screw  119  loosened, the counter rotating gear case  100  maybe slid off the drive shaft  15  of the host drive unit  10 . At this point, the original prop may be reinstalled, or a different counter rotating gear case  100  may be installed and/or different props. 
     Following long-standing patent law convention, the terms “a,” “an,” and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to “a subject” includes a plurality of subjects, unless the context clearly is to the contrary (e.g., a plurality of subjects), and so forth. 
     Throughout this specification and the claims, the terms “comprise,” “comprises,” and “comprising” are used in a non-exclusive sense, except where the context requires otherwise. Likewise, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items. 
     For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing amounts, sizes, dimensions, proportions, shapes, formulations, parameters, percentages, quantities, characteristics, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are not and need not be exact, but may be approximate and/or larger or smaller as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art depending on the desired properties sought to be obtained by the subject matter of the present invention. For example, the term “about,” when referring to a value can be meant to encompass variations of, in some embodiments ±100%, in some embodiments ±50%, in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions. 
     Further, the term “about” when used in connection with one or more numbers or numerical ranges, should be understood to refer to all such numbers, including all numbers in a range and modifies that range by extending the boundaries above and below the numerical values set forth. The recitation of numerical ranges by endpoints includes all numbers, e.g., whole integers, including fractions thereof, subsumed within that range (for example, the recitation of 1 to 5 includes 1, 2, 3, 4, and 5, as well as fractions thereof, e.g., 1.5, 2.25, 3.75, 4.1, and the like) and any range within that range. 
     Although the foregoing subject matter has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be understood by those skilled in the art that certain changes and modifications can be practiced within the scope of the appended claims.