Patent Publication Number: US-10315747-B1

Title: Outboard motors having transmissions with laterally offset input and output driveshafts

Description:
FIELD 
     The present disclosure relates to outboard motors, and more particularly to transmissions for outboard motors. 
     BACKGROUND 
     This Background and Summary are provided to introduce a selection of concepts that are further described below in the Detailed Description. The Background and Summary are not intended to identify key or essential features of the claimed subject matter, nor are they intended to be used as an aid in limiting the scope of the claimed subject matter. 
     The following U.S. Patents and Application are incorporated herein by reference: 
     U.S. Pat. No. 3,994,254 discloses a multiple-speed transmission for coupling an engine to the impeller of a marine jet drive, such that an overdrive connection powers the jet drive under operating conditions up to a predetermined upper limit of cruising speeds and such that a reduced drive, for example a direct-drive connection, is automatically established for jet-drive speeds in excess of the cruising conditions. 
     U.S. Pat. No. 5,018,996 discloses a fluid coupling transmission adapted for interposition between the engine and the propulsion unit of a marine drive. The fluid coupling transmission provides variable speed operation in both forward and reverse. A fluid pump is drivingly connected to the engine crankshaft, and is adapted to drive a turbine. A series of variable position vanes are disposed between the fluid pump and turbine at the entrance of fluid into the pump, for controlling the power transfer there between by controlling the amount of fluid passing through the pump and acting on the turbine. A ring gear is connected to the turbine, and a sun gear is connected to the output shaft of the transmission. One or more planet gears are provided between the ring gear and the sun gear, and are rotatably mounted to a carrier member, which extends coaxially with respect to the output shaft. An output control mechanism, including a brake band and a plate clutch mechanism, is selectively engageable with the carrier member so as to control the direction of rotation of the transmission output shaft. 
     U.S. Pat. No. 6,755,703 discloses a hydraulic assist mechanism for use in conjunction with a gear shift device that provides a hydraulic cylinder and piston combination connected by a linkage to a gear shift mechanism. Hydraulic pressure can be provided by a pump used in association with either a power trim system or a power steering system. Hydraulic valves are used to pressurize selected regions of the hydraulic cylinder in order to actuate a piston which is connected, by an actuator, to the gear shift mechanism. 
     U.S. Pat. No. 7,544,110 discloses an actuator for a marine transmission that uses four cavities of preselected size in order to provide four potential forces resulting from pressurized hydraulic fluid within those cavities. The effective areas of surfaces acted upon by the hydraulic pressure are selected in order to provide increased force to move the actuator toward a neutral position from either a forward or reverse gear position. Also, the relative magnitudes of these effective areas are also selected to provide a quicker movement into gear than out of gear, given a similar differential magnitude of pressures within the cavities. 
     U.S. Pat. No. 9,441,724 discloses a method of monitoring and controlling a transmission in a marine propulsion device that comprises the steps of receiving a rotational input speed of an input shaft to the transmission, receiving a rotational output speed of an output shaft from the transmission, receiving a shift actuator position value, and receiving an engine torque value. The method further comprises calculating a speed differential based on the input speed and the output speed, and generating a slip profile based on a range of speed differentials, engine torque values, and shift actuator position values. 
     U.S. patent application Ser. No. 14/585,872 discloses a transmission for a marine propulsion device having an internal combustion engine that drives a propulsor for propelling a marine vessel in water. An input shaft is driven into rotation by the engine. An output shaft drives the propulsor into rotation. A forward planetary gearset that connects the input shaft to the output shaft so as to drive the output shaft into forward rotation. A reverse planetary gearset that connects the input shaft to the output shaft so as to drive the output shaft into reverse rotation. A forward brake engages the forward planetary gearset in a forward gear wherein the forward planetary gearset drives the output shaft into the forward rotation. A reverse brake engages the reverse planetary gearset in a reverse gear wherein the reverse planetary gearset drives the output shaft into the reverse rotation. 
     SUMMARY 
     An outboard motor comprises an engine, an input driveshaft that is caused to rotate by the engine, an output driveshaft that extends parallel to and is laterally spaced apart from the input driveshaft, and a transmission that operatively connects the input driveshaft to the output driveshaft such that rotation of the input driveshaft causes rotation of the output driveshaft. The transmission is positionable into a forward gear in which forward rotation of the input driveshaft causes forward rotation of the output driveshaft, a reverse gear in which forward rotation of the input driveshaft causes reverse rotation of the output driveshaft, and neutral wherein forward rotation of the driveshaft does not cause rotation of the output driveshaft. A propulsor shaft transversely extends relative to the output driveshaft. A beveled gearset operatively couples the output driveshaft to the propulsor shaft so that rotation of the output driveshaft causes rotation of the propulsor shaft. Various other features, objects and advantages of the disclosure will be made apparent from the following description taken together with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate the best mode presently contemplated of carrying out the concepts of the present disclosure. The same numbers are used throughout the drawings to reference like features and like components. In the drawings: 
         FIG. 1  is a perspective view of a lower gearcase on an outboard motor. 
         FIG. 2  is a perspective view looking downward at a transmission for the outboard motor. 
         FIG. 3  is a perspective view looking upward at the transmission. 
         FIG. 4  is an exploded view of the transmission. 
         FIGS. 5-7  are view of section  5 - 5  taken in  FIG. 1 , showing alternative power flows through the transmission. 
         FIG. 8  is a view of section  5 - 5  taken in  FIG. 1 , showing a lubrication circuit for the transmission. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     During research and development of outboard motors, the present inventors have determined that dual propeller outboard motors offer several performance improvements over single propeller motors. However it can be difficult to design a dual propeller outboard motor that meets all performance goals and has little detrimental impact to the overall design of the outboard motor. Typical outboard motors transfer power through a driveshaft from a powerhead to a right angle gearset (i.e. a pinion with forward and reverse gears) that turns a propeller shaft. Shifting is typically accomplished with a clutching system, typically a dog clutch, which is moved from one gear to the other depending on the user&#39;s command. Through research and development, the present inventors have invented a transmission assembly for an outboard motor that allows use of several different types of clutching systems and adds an additional gear set and pressure lubrication to utilize dual counter rotating propellers within a traditional outboard motor structure. The transmission apparatuses disclosed herein provide simple direct mechanical activation of a shifting mechanism, to thereby provide a durable system for consistent performance. Dual parallel driveshafts allow for utilization of a simple gearset to provide the proper total output ratio. Several different clutching options provide function within a minimum package size. Dual floating idler gears provide power transfer within a minimum package size. A lubrication circuit provides lubrication where needed. A replaceable filter provides protection from debris in the system. 
       FIGS. 1-8  depict portions of an outboard motor  10  according to the present disclosure. The outboard motor  10  includes a transmission housing  12  and a lower gearcase housing  14 , which are located below a (not shown) driveshaft housing of the outboard motor  10 . The outboard motor  10  includes an internal combustion engine, shown schematically at  16  in  FIG. 1 . As is conventional, the internal combustion engine  16  is configured to cause rotation of an input driveshaft  18  that extends along an input driveshaft axis  20  into the transmission housing  12 . 
     Referring to  FIGS. 2-7 , a transmission  22  operatively connects the input driveshaft  18  to an output driveshaft  24  that extends parallel to and is laterally spaced apart from the input driveshaft  18 . As described further herein below, the transmission  22  is positionable into and between a forward gear ( FIG. 6 ) in which forward rotation of the input driveshaft  18  causes forward rotation of the output driveshaft  24 , a reverse gear ( FIG. 7 ) in which forward rotation of the input driveshaft  18  causes reverse rotation of the output driveshaft  24 , and neutral ( FIG. 5 ) wherein forward rotation of the input driveshaft  18  does not cause rotation of the output driveshaft  24 . 
     Referring to  FIGS. 5-7 , a propulsor shaft  26  transversely extends relative to the output driveshaft  24 . The propulsor shaft  26  is located in the lower gearcase housing  14  and is rotationally connected to a propulsor  28  (see  FIG. 1 ) which rotates with the propulsor shaft  26 . In the illustrated example, the propulsor  28  includes a pair of counter rotating propellers  30  that are configured to interact with the surrounding body of water to propel the marine vessel to which the outboard motor  10  is attached. The type and configuration of the propulsor  28  can vary from that which shown and for example can include different propeller configurations, impellers, and/or the like. A conventional beveled gearset  31  (see  FIGS. 5-8 ) operatively couples the output driveshaft  24  to the propulsor shaft  26  so that rotation of the output driveshaft  24  causes corresponding rotation of the propulsor shaft  26 . 
     Referring to  FIGS. 2-7 , the transmission  22  includes a reverse driving gear  32  on the input driveshaft  18  and a reverse driven gear  34  on the output driveshaft  24 . The reverse driving rear  32  is rotatably fixed to the input driveshaft  18  and the reverse driven gear  34  is rotatably fixed to the output driveshaft  24 . The reverse driving gear  32  and reverse driven gear  34  are meshed together such that forward rotation of the input driveshaft  18  causes forward rotation of the reverse driving gear  32 , which thereby causes reverse rotation of the reverse driven gear  34 . Reverse rotation of the reverse driven gear  34  causes reverse rotation of the output driveshaft  24 . Reverse rotation of the output driveshaft  24  causes reverse rotation of the propulsor shaft  26 , via the beveled gearset  31 . Reverse rotation of the propulsor shaft  26  causes the propulsor  28  to rotate so that a reverse thrust is imparted on the marine vessel. 
     The transmission  22  also includes a forward driving gear  37  on the input driveshaft  18 , a forward driven gear  38  on the output driveshaft  24 , and a pair of idler gears  40  that is meshed between so as to connect the forward driving gear  36  and the forward driven gear  38 . The pair of idler gears  40  is supported by a floating idler gear mounting bracket  41  carrying pivot axles  43  about which the pair of idler gears  40  rotates. The forward driving gear  37  is rotatably fixed to the input driveshaft  18  and the forward driven gear  38  is rotatably fixed to the output driveshaft  24 . Forward rotation of the input driveshaft  18  causes forward rotation of the forward driving gear  36 , which causes reverse rotation of the pair of idler gears  40 , which causes forward rotation of the forward driven gear  38 . Forward rotation of the forward driven gear  38  causes forward rotation of the output driveshaft  24 . Forward rotation of the output driveshaft  24  causes forward rotation of the propulsor shaft  26  via the beveled gearset  31 , which causes the propulsor  28  to rotate so that a forward thrust is imparted on the marine vessel. 
     In the illustrated embodiment, a cone clutch  42  is operable to position the transmission  22  into and between the above-described forward gear in which forward rotation of the input driveshaft  18  causes forward rotation of the propulsor shaft  26 , reverse gear in which forward rotation of the input driveshaft  18  causes reverse rotation of the propulsor shaft  26 , and neutral in which forward rotation of the input driveshaft  18  does not cause forward or reverse rotation of the propulsor shaft  26 . The type and configuration of clutch can vary from that which is shown. In the illustrated example, the cone clutch  42  has a central cone  44  that is coupled to the input driveshaft  18 , for example via helical or axial splines  45 , so that rotation of the input driveshaft  18  causes rotation of the central cone  44  in each of the noted forward gear, reverse gear and neutral. The central cone  44  is axially movable, e.g., slideable, along the input driveshaft  18  into and between a reverse position ( FIG. 7 ) in which the central cone  44  enacts the reverse gear, a forward position ( FIG. 6 ) in which the central cone  44  enacts the forward gear, and a neutral position ( FIG. 5 ), in which the central cone  44  enacts neutral. In other examples, the clutch can include a mechanical actuated wet plate clutch, an electro actuated wet plate clutch, a dog clutch, and/or the like. 
     The cone clutch  42  includes a reverse cone  46  that is fixed to the reverse driving gear  32 . When the transmission  20  is engaged in the noted reverse gear, the central cone  44  engages the reverse cone  46  so that rotation of the central cone  44  causes rotation of the reverse cone  46  and thus rotation of the reverse driving gear  32 . The cone clutch  42  further includes a forward cone  48  that is fixed to the forward driving gear  36 . When the transmission  20  is engaged in the noted forward gear, the central cone  44  engages the forward cone  48  so that rotation of the central cone  44  causes rotation of the forward cone  48  and thus rotation of the forward driving gear  36 . 
     A shift actuator  50  is configured to axially move the central cone  44  along the input driveshaft  18  so as to enact the noted reverse, neutral and forward gears. The shift actuator  50  includes a shift shaft  51  and a camming mechanism  52  that cams the shift shaft  51  up and down with respect to a shift shaft axis  54  upon rotation of the shift shaft  50  in opposite directions about the shift actuator axis  54 . The camming mechanism  52  includes shifter plates  53 , each having a contoured camming surface  55 . Rotation of the shifter plates  53  with respect to the shift shaft axis  54  causes the contoured camming surfaces  55  to engage the reverse or forward cone  46 ,  48  and thus causes the camming mechanism  52  and shift shaft  51 , to raise or lower depending on the direction of rotation. A shift fork  56  is sandwiched between the shifter plates  53  and travels with the shifter plates  53  along the shift shaft axis  54 . The shift fork  56  connects the shift actuator  50  to the central cone  44  such that movement of the shift actuator  50  up and down causes commensurate movement of the central cone  44  up and down along the input driveshaft  18  into the reverse and forward gear positions described herein above. 
     A detent mechanism  58  detents the shift actuator  50  in its neutral position along the shift actuator axis  54 . The detent mechanism  58  includes a ball  59  that is biased into engagement with the shift shaft  51  by a spring  61  when the shift shaft  51  is located in neutral. Rotation of the shift shaft  51  about the shift shaft axis  54  causes the camming mechanism  52  to overcome the bias of the spring  61  and allows the shift shaft  51  to move out of the neutral position. Opposite rotation of the shift shaft  51  about the shift shaft axis  54  causes the camming mechanism  52  to bring the shift shaft  51  back into the neutral position wherein the spring  61  biases the ball  59  back into engagement with the shift shaft  51  to retain the shift shaft  51  in the neutral position. 
     In operation, rotation of the shift shaft  51  rotates the camming mechanism  52 , as described above, to thereby raise or lower the shift fork  56  depending on the direction of rotation. The shift fork  56  carries the cone clutch  42  up or down on the input driveshaft  18 , to thereby enact the above-described reverse gear, forward gear, and neutral 
     Referring to  FIG. 8 , a lubrication circuit  60  provides lubrication to the transmission  22 . A lubrication pump  62  (for example a Gerotor) is coupled to the input driveshaft  18 . Rotation of the input driveshaft  18  causes the lubrication pump  62  to pump the lubrication through the lubrication circuit  60 . A lubrication reservoir  64  is located in the lower gearcase housing  14 . The lubrication pump  62  draws lubrication from the lubrication reservoir  64  through a conduit  65  having a filtering screen, and pumps the lubrication to the transmission  22 , specifically via axial channels  66  and a plurality of transverse openings  68  in the input driveshaft  18  and output driveshaft  24 . Via the transverse openings  68 , the lubrication is sprayed onto the surfaces of the cone clutch  42  requiring lubrication. The lubrication drains by gravity through the transmission  22 , back to the lubrication reservoir  64 . A replaceable filter  70  is disposed in the lubrication circuit  60 . The lubrication pump  62  is configured to pump the lubrication through the replaceable filter  70  and then to the transmission  22  via the axial channels  66  and transverse openings  68 . A spring-actuated bypass check valve  72  opens under pressure from the lubrication when the replaceable filter  70  becomes plugged and allows flow of lubrication to bypass the filter  70  on its way to the transmission  22 . 
     This written description uses examples to disclose embodiments of a marine propulsion device, including the best mode, and also to enable any person skilled in the art to make and use the same. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.