Patent Abstract:
A lubricated gear coupling for transmitting torque between an input shaft and an output shaft, comprising a first hub connected to the input shaft, the first hub comprising at least one gear tooth and a first raised edge, a second hub non-rotatably connected to the output shaft, the second hub comprising at least one gear tooth and a second raised edge, a sleeve gear comprising at least one gear tooth, wherein the first hub and the second hub are arranged within the sleeve gear, the gear tooth of the first hub and second hub corresponding with the gear tooth of the sleeve gear, wherein torque is transmitted from the input shaft to the output shaft with axial, radial, and angular movement occurring between the first hub and the second hub and, a draining means arranged on the sleeve gear, wherein the lubricant can flow through.

Full Description:
FIELD OF THE INVENTION 
     The invention relates generally to a gear coupling, and more specifically to an oil lubricated gear coupling. 
     BACKGROUND OF THE INVENTION 
     Couplings are used to transmit torque and rotational movement between two machines, where the input and output shafts are misaligned axially, radially, angularly, or a combination of the aforementioned. Different types of couplings have different characteristics and are used in different applications. 
     Gear couplings have high torque, high misalignment, and moderate speed capability with high torsional stiffness. Gear couplings are usually lubricated by grease, which tends to remain in a cylindrical shape around the outside of the sleeve gear away from the sealing devices. Grease lubricated gear couplings with low misalignment may use contact seals outboard of the gear teeth, while high misalignment couplings may have lips on the end plates extending under the hub gear teeth. However, it is sometimes advantageous to use a lubricant that has low viscosity such as oil where it is difficult or expensive to dismantle the associated machines, to enable the lubricant to be replaced by draining and refilling the coupling using suitable plugs. However, the use of a low viscous lubricant creates sealing problems, in particular, where the couplings are subject to frequent starting and stopping applications. 
     One embodiment of a lubricated gear coupling is disclosed in U.S. Pat. No. 6,171,197 (Boucquey) which discloses a coupling that allows angular and radial misalignment as well as axial displacement between two shafts. The coupling comprises two hubs, a sleeve tube, stop means to prevent excessive displacement, and sealing rings. Boucquey fails to disclose or teach, however, a lubricated gear coupling with plugs that can be removed and replaced in order to drain and fill lubricant. Boucquey also fails to disclose a channel between sealing rings which aids in preventing any contaminant from entering the chamber containing the lubricant. Instead, Boucquey teaches a lubricated gear coupling with a sealing ring that experiences negligible radial displacement when misalignment occurs and is the sole means for preventing any contamination of the lubricant. 
     Another embodiment of a lubricated gear coupling is disclosed in U.S. Pat. No. 6,524,191 (Tennies) which discloses an inverted coupling for transmitting power between the shafts of an electric motor and a gear box pinion. The coupling has a shaft hub mounted on the motor shaft, a gearbox hub mounted on the gearbox shaft, annular splines, sleeve ring gears, and a coupling member sleeve seal. Tennies fails to disclose or teach, however, a separate contaminant excluding seal in addition to the lubricant retaining seal. Tennies also fails to disclose a channel between sealing rings which aids in preventing any contaminant from entering the chamber containing the lubricant. 
     Yet another embodiment of a lubricated gear coupling is disclosed in United States Application Publication No. 2011/0012314 (Nakamura) which discloses an apparatus having a first member, a second member, a first sealing body, and a second sealing body. The lubricant is sealed between the first member and the second member by the first sealing body. The second sealing body is disposed adjacent to the first sealing body opposite the lubricant and slides from a reserve position to a sealing position in the event that the first sealing body is compromised. Each sealing body includes an oil seal and a dust seal. Nakamura fails to disclose or teach, however, a lubricated gear coupling that has individual seals for retaining lubricant and excluding contaminant. Additionally, Nakamura fails to disclose plugs that can be removed and replaced in order to drain and fill the lubricant. Instead, Nakamura teaches a sealing body that has the second sealing body in a reserve position and only functions as a seal when moved into a sealing position after the first sealing body has become compromised. 
     Thus, there exists a long felt need for a lubricated gear coupling that contains two separate seals for retaining lubricant and excluding contaminant from the lubricant, a means for easily draining the lubricant without completely dismantling the gear coupling, and having features within the gear coupling to minimize the amount of lubricant that migrates towards the lubricant seal. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention broadly includes a lubricated gear coupling for transmitting torque between an input shaft and an output shaft, comprising a first hub connected to the input shaft, the first hub comprising at least one gear tooth and a first raised edge, a second hub non-rotatably connected to the output shaft, the second hub comprising at least one gear tooth and a second raised edge, a sleeve gear comprising at least one gear tooth, wherein the first hub and the second hub are arranged within the sleeve gear, the gear tooth of the first hub and second hub corresponding with the gear tooth of the sleeve gear, wherein torque is transmitted from the input shaft to the output shaft with axial, radial, and angular movement occurring between the first hub and second hub, and a draining means arranged on the sleeve gear, wherein the lubricant can flow through. 
     The invention also comprises a first, second, third, and fourth seal, wherein the first seal and the second seal are operatively arranged between the first hub and the sleeve gear, the first seal preventing discharge of the lubricant, the second seal preventing contamination of the lubricant. The third seal and the fourth seal are operatively arranged between the second hub and the sleeve gear, the third seal preventing discharge of the lubricant, and the fourth seal preventing contamination of the lubricant. 
     A general object of the invention is to provide a lubricated gear coupling which performs the same function as prior gear couplings but minimizes the contamination or discharge of the lubricant. 
     A further object of the invention is to provide a cost savings for the maintenance and lubricant replacement of a lubricated gear coupling. 
     These and other objects, features and advantages of the present invention will become readily apparent upon a reading and review of the following detailed description of the invention, in view of the appended drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying figures, in which: 
         FIG. 1  is a perspective view of the gear coupling of the present invention; 
         FIG. 2  is a front view of the gear coupling; 
         FIG. 3  is a back view of the gear coupling; 
         FIG. 4  is a side view of the gear coupling; 
         FIG. 5  is a perspective view of input hub  12  and output hub  22 ; 
         FIG. 6  is a perspective view of the gear coupling with second end plate  50   b  removed; and, 
         FIG. 7  is a cross sectional view of the gear coupling, taken generally along line  7 - 7  in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. It is to be understood that the invention as claimed is not limited to the disclosed aspects. 
     Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention as claimed. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention pertains. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention. 
     Adverting now to the figures,  FIG. 1  is a perspective view of gear coupling  10  which broadly comprises input hub  12  (shown in  FIG. 2 ), output hub  22 , first sleeve gear  30 , second sleeve gear  36 , first end plate  50   a , second end plate  50   b , bolts  60 , nuts  62 , drain plugs  65   a  (shown in  FIG. 4 ), and drain plugs  65   b . Input hub  12  and output hub  22  are arranged within first sleeve gear  30  and second sleeve gear  36 , respectively. First sleeve gear  30  and second sleeve gear  36  are secured to one another by bolts  60  and nuts  62  which are operatively arranged on flange  31  of first sleeve gear  30  and flange  37  of second sleeve gear  36 . First end plate  50   a  is secured to first sleeve gear  30  by retaining screws  51   a . Additionally, second end plate  50   b  is secured to second sleeve gear  36  by retaining screws  51   b . Lubricant  72  (shown in  FIG. 7 ) is enclosed within first sleeve gear  30  and second sleeve gear  36  which reduces friction between input hub  12  and first sleeve gear  30  and between output hub  22  and second sleeve gear  36  while in operation (shown in  FIG. 7 ). Drain plugs  65   a  (shown in  FIG. 4 ) are operatively arranged on exterior surface  33  of first sleeve gear  30  to allow for the removal and replacement of lubricant  72  within first sleeve gear  30 . Additionally, drain plugs  65   b  are operatively arranged on exterior surface  39  of second sleeve gear  36  to allow for the removal and replacement of lubricant  72  within second sleeve gear  36 . This allows a user to perform regular maintenance on gear coupling  10  without completely dismantling gear coupling  10 . In a preferred embodiment, drain plugs  65   a  and  65   b  are screws which engage and secure with threaded inserts on exterior surfaces  33  and  39  of first sleeve gear  30  and second sleeve gear  36 . It should be appreciated, however, that the use of different types of removable plugs is possible and considered to be within the scope of the invention as claimed. 
       FIG. 2  and  FIG. 3  are a front and back view of gear coupling  10 , respectively. As shown in the figures, retaining plate  42  is concentrically arranged within input hub  12 . Retaining plate fastener  44  and pins  45  are operatively arranged on retaining plate  42 , which would engage an input means such as a shaft (not shown) to rotate gear coupling  10 . An input means (not shown) would also engage sleeve  40 , which is concentrically arranged within input hub  12 , in order to limit the torque applied to gear coupling  10 . In a preferred embodiment, retaining screws  51   a  and  51   b  are arranged symmetrically on the face of first end plate  50   a  and second end plate  50   b , respectively. Additionally, screws  60  and nuts  62  are symmetrically arranged on flanges  31  and  37  of first sleeve gear  30  and second sleeve gear  36 . It should be appreciated, however, that different asymmetrical arrangements are possible and considered to be within the scope of the invention as claimed. 
       FIG. 4  is a side view of gear coupling  10 . As shown in the figure, input hub  12  is co-linear with output hub  22  and first sleeve gear  30  is co-linear with second sleeve gear  36 . Input hub  12 , output hub  22 , first sleeve gear  30 , and second sleeve gear  36  all rotate about axis  80  while gear coupling  10  is in operation and no misalignment occurs. It is important to note that input hub  12  and output hub  22  can be misaligned axially, radially, and angularly. Also shown in the figure is the symmetrical arrangement of drain plugs  65   a  on exterior surface  33  of first sleeve gear  30  and the symmetrical arrangement of drain plugs  65   b  on exterior surface  39  of second sleeve gear  36 . It is also shown that input shaft IS and output shaft OS are secured within input hub  12  and output hub  22 , respectively. In a preferred embodiment, input hub  12  is secured to input shaft IS via an interference fit and output hub  22  is secured to output shaft OS via an interference fit. 
       FIG. 5  is a perspective view of input hub  12  and output hub  22 . Input hub  12  comprises gear teeth  14 , first surface  16 , second surface  18 , and sleeve  40 . Output hub  22  comprises gear teeth  24 , first surface  26 , and second surface  28  (shown in  FIG. 7 ). In a preferred embodiment, input hub  12  and output hub  22  are manufactured from a high strength material such as steel. It should be appreciated, however, that the use of different materials is possible and considered to be within the scope of the invention as claimed. For example, input hub  12  and output hub  22  could be manufactured from a composite material if the operating environment is corrosive to steel or a ductile iron if stresses are within an acceptable range. Additionally, gear teeth  14  and gear teeth  24  comprise a spherical crown at the outer most edge of each gear tooth and axially tapered flank  14   a  and  24   a , respectively, to permit angular misalignment. 
       FIG. 6  is a perspective view of gear coupling  10  with second end plate  50   b  removed from second sleeve gear  36 . As shown in the figure, gear teeth  38  are concentrically arranged within sleeve gear  36 . Output hub  22  is substantially non-rotatable with respect to second sleeve gear  36  via gear teeth  38  engaging with gear teeth  24  of output hub  22  (shown in  FIG. 7 ). Gear teeth  38  and gear teeth  24  are designed to allow for axial, radial, or angular misalignment of input hub  12  and output hub  22 . Additionally, gear teeth  14  of input hub  12  and gear teeth  32  of first sleeve gear  30  are designed to allow for axial, radial, or angular misalignment of input hub  12  and output hub  22 . In order to ensure that output hub  22  stays engaged with sleeve gear  36  via gear teeth  24  and gear teeth  38  while misalignment occurs, bump stops  58   c  and  58   d  are concentrically arranged within second sleeve gear  36  at the sides of gear teeth  38 . In a preferred embodiment, bump stops  58   a ,  58   b ,  58   c , and  58   d  are manufactured from rubber seals. It should be appreciated, however, that any suitable material could be used such as plastic or metal. As misalignment between input hub  12  and output hub  22  occurs while gear coupling  10  is in operation, output hub  22  slides axially, radially, and angularly within second sleeve gear  36  along gear teeth  38  and gear teeth  24  to ensure that there is no excessive torque or stress on gear coupling  10 . Additionally, input hub  12  slides axially, radially, and angularly within first sleeve gear  30  along gear teeth  32  and gear teeth  14  due to misalignment of input hub  12  and output hub  22  while gear coupling  10  is in operation (shown in  FIG. 7 ). To ensure that gear teeth  14  of input hub  12  stay engaged with gear teeth  32  of first sleeve gear  30 , bump stops  58   a  and  58   b  are concentrically arranged within first sleeve gear  30  at the sides of gear teeth  32  (shown in  FIG. 7 ). In a preferred embodiment, gear teeth  12 ,  24 ,  32 , and  38  are substantially similar to spur gears which allow axial, angular, and radial displacement of input hub  12  and output hub  22  while having input hub  12  engaged with first sleeve gear  30  and output hub  22  engaged with second sleeve gear  36 . It should be appreciated, however, that the use of different gear configurations is possible and considered to be within the scope of the invention as claimed. For example, a planetary gear could be used to transmit torque from input hub  12  to first sleeve gear  30  but a spur gear can be used to transmit torque from second sleeve gear  36  to output hub  22 . 
       FIG. 7  is a cross section of gear coupling  10  taken generally along line  7 - 7  in  FIG. 2 . As shown in the figure, first end plate  50   a  comprises extension  52 , surface  52   a , and surface  52   b  and second end plate  50   b  comprises extension  53 , surface  53   a , and surface  53   b . Retaining seal  54   a  is arranged between extension  52  and input hub  12  along surface  52   b  of extension  52  and surface  18  of input hub  12 . Additionally, retaining seal  54   b  is arranged between extension  53  and output hub  22  along surface  52   b  of extension  52  and surface  18  of input hub  12 . Lubricant  72  is arranged between gear teeth  14  of input hub  12  and gear teeth  32  of first sleeve gear  30  as well as between gear teeth  24  of output hub  22  and gear teeth  38  of second sleeve gear  36  to reduce friction during misalignment. Input hub  12  and output hub  22  have raised edges  74   a  and  74   b , respectively, to mitigate lubricant  72  from approaching retaining seals  54   a  and  54   b  while gear coupling  10  is in operation. To prevent contamination of lubricant  72 , excluding seal  56   a  is arranged between extension  52  and input hub  12  along surface  52   a  of extension  52  and surface  16  of input hub  12 . Additionally, excluding seal  56   b  is arranged between extension  53  and output hub  22  along surface  53   a  of extension  53  and surface  26  of output hub  22 . In a preferred embodiment, retaining seals  54   a  and  54   b  and excluding seals  56   a  and  56   b  are rubber lip seals. It should be appreciated, however, that the use of different materials for the seals is possible and considered to be within the scope of the invention as claimed. Additionally, seals  54   a  and  56   a  are arranged within recesses  12   a  and  12   b  of input hub  12 , respectively, while seals  54   b  and  56   b  are arranged within recesses  22   a  and  22   b  of output hub  22 , respectively. Channel  75   a  is formed between input hub  12  and extension  52  and allows for axial, radial, and angular movement of input hub  12  with relation to first sleeve gear  30 . Channel  75   b  is formed between output hub  22  and extension  53  and allows for the axial movement of output hub  22  with relation to second sleeve gear  36 . Channel  75   a  and  75   b  also aid in preventing contamination of lubricant  72  if excluding seals  56   a  or  56   b  begin to fail and stop preventing substances from migrating towards retaining seals  54   a  and  54   b . The design of channels  75   a  and  75   b  pull contaminants away from retaining seals  54   a  and  54   b  while gear coupling  10  is in operation. 
     To ensure lubricant  72  is retained within gear coupling  10 , besides the use of retaining seals  54   a  and  54   b , static seal  68  is operatively arranged between first end plate  50   a  and first sleeve gear  30  and static seal  70  is operatively arranged between second end plate  50   b  and second sleeve gear  36 . Additionally, static seal  69  is arranged between first sleeve gear  30  and second sleeve gear  36  in order to achieve a tight seal which lubricant  72  cannot pass through since the bolted connection between first sleeve gear  30  and second sleeve gear  36  is not sufficient to keep lubricant  72  within gear coupling  10 . In a preferred embodiment, lubricant  72  is a fluid such as oil, which allows for lubricant  72  to not only have superior friction reducing capabilities, but also allows for the removal and replacement of lubricant  72  within gear coupling  10  by simply removing drain plugs  65   a  and  65   b . It should be appreciated, however, that the use of different friction reducing substances is possible and considered to be within the scope of the invention as claimed. For example, a grease could be used within gear coupling  10 . 
     It will be appreciated that various features of the above-described invention and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. 
     LIST OF REFERENCE NUMBERS 
     
         
           10  gear coupling 
           12  input hub 
           14  gear teeth 
           16  first surface 
           18  second surface 
           22  output hub 
           24  gear teeth 
           26  first surface 
           28  second surface 
           30  first sleeve gear 
           31  flange 
           32  gear teeth 
           33  exterior surface 
           36  second sleeve gear 
           37  flange 
           38  gear teeth 
           39  exterior surface 
           40  sleeve 
           42  retaining plate 
           44  retaining plate fastener 
           45  pin 
           50   a  first end plate 
           50   b  second end plate 
           51   a  retaining screw 
           51   b  retaining screw 
           52  extension 
           52   a  first surface 
           52   b  second surface 
           53  extension 
           53   a  first surface 
           53   b  second surface 
           54   a  retaining seal 
           54   b  retaining seal 
           56   a  excluding seal 
           56   b  excluding seal 
           58   a  bump stop 
           58   b  bump stop 
           58   c  bump stop 
           58   d  bump stop 
           60  bolt 
           62  nut 
           65   a  drain plug 
           65   b  drain plug 
           68  static seal 
           69  static seal 
           70  static seal 
           72  lubricant 
           74   a  raised edge 
           74   b  raised edge 
           75   a  channel 
           75   b  channel 
           80  axis

Technology Classification (CPC): 5