Patent Publication Number: US-8529305-B2

Title: Electric outboard drive

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an outboard drive for propelling a boat and more particularly, to an electric outboard drive that is lightweight and low-pollution. 
     2. Description of the Related Art 
     An outboard drive for attaching to the transom of a boat is a propulsion system adapted to be especially used for small watercrafts, such as pneumatic boats and speedboats. To date, most of the outboard drives utilize gasoline engines as their power source. However, the gasoline engine will produce loud noise when it is running and the exhausted waste gas after combustion of gasoline will adversely affect the health of passages and the environment. In addition, the gasoline engine may discharge oil soil, which will contaminate water. Therefore, the outboard drives adopting gasoline engine as power source may be an unpopular option because they can hardly meet the environment protection requirements nowadays. Further, in order to effect the steering control of the boat, the outboard drive needs to be equipped with a steering mechanism, which is usually complicated in its structure, thereby raising the manufacturing coats. Furthermore, conventional gasoline engines are heavy in weight; therefore, they can not be conveniently detached from the boat for transportation and storage, thereby increasing the risk of being stolen. 
     U.S. Pat. No. 7,614,925 disclosed a transportable outboard motor which utilizes an electric motor as its power source. Using an electric motor substituting for the gasoline engine is an environmentally friendly option that can improve the above-mentioned disadvantages of the gasoline-powered outboard drive. However, in the aforesaid US patent, the electric motor is configured to be installed inside the pylon that has a limit space, which in turn limits the specifications of the electric motors that can be used in this design, i.e. a big electric motor having a relatively big power output may not be used in the aforesaid design. This setup limits the power output of the outboard drive, resulting in that the power output provided by this kind of electric outboard motor may be insufficient for a lager boat. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished in view of the above-noted circumstances. It is therefore one objective of the present invention to provide an electric outboard drive which is compact in configuration, light in weight, and low in pollution. 
     Another objective of the present invention is to provide an electric outboard drive, in which various sizes of electric motors without a special limit in specification can be used so as to provide sufficient power to propel the boat. 
     To achieve the above-mentioned objectives, the electric outboard drive provided by the present invention comprises a driving device, a mounting bracket, a propelling device and a connecting tube. The driving device includes a motor housing, an electric motor mounted inside the housing and provided with an output shaft, and a first transmission shaft extending downwardly and having a top end connected with the output shaft of the electric motor. The mounting bracket is adapted for being detachably mounted to the transom of the boat. The housing of the driving device is rotatably connected with the mounting bracket. The propelling device includes a fluid guiding member, a second transmission shaft and a propeller. A bottom end of the first transmission shaft extends into the fluid guiding member. The second transmission shaft is transversely and rotatably disposed in the fluid guiding member and provided with a front end engaged with the bottom end of the first transmission shaft, and a rear end extending out of the fluid guiding member. The propeller is connected with the rear end of the second transmission shaft. The connecting tube is connected between the motor housing of the driving device and the fluid guiding member of the propelling device and houses the first transmission shaft. As a result, when the electric motor drives the first transmission shaft to rotate, the second transmission shaft, which is synchronously rotated with the first transmission shaft, will drive the propeller to rotate so as to propel the boat. 
     It can be understood from the above-mentioned description that the electric outboard drive of the present invention utilizes the electric motor substituting for the conventional gasoline engine to reduce its overall weight and lower the pollution of the exhausted waste gas produced by the gasoline engine, such that the electric outboard drive of the present invention can meet the environmental protection requirement and be easily detached from the boat for storage and/or transportation. In addition, the motor used in the electric outboard drive of the present invention is not limited to special specifications. In other words, various electric motors having different sizes and powers can be chosen for providing sufficient propulsion power according to the actual need. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a perspective view of an electric outboard drive according to a preferred embodiment of the present invention; 
         FIG. 2  is a schematic drawing showing that the electric outboard drive of the present invention is mounted to the transom of a boat; 
         FIG. 3  is a partially exploded view of the electric outboard drive of the preferred embodiment of the present invention; 
         FIG. 4  is a cross-sectional view of the electric outboard drive of the preferred embodiment of the present invention; 
         FIG. 5  is a top view of the electric outboard drive of the preferred embodiment of the present invention; 
         FIG. 6  is similar to  FIG. 5 , but showing that the propeller is revolved counterclockwise; and 
         FIG. 7  is similar to  FIG. 5 , but showing that the propeller is revolved clockwise. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIGS. 1-2 , an electric outboard drive  20  provided according to a preferred embodiment of the present invention is adapted to be mounted on a transom  12  of a boat  10 . The electric outboard drive  20  comprises mainly a driving device  30 , a mounting bracket  40 , a propelling device  50  and a connecting tube  60 . Referring to  FIGS. 1-4 , the driving device  30  includes a motor housing  31 , an electric motor  32  and a first transmission shaft  34 . The motor housing  31  has a hollow shell  35  and a base  36  on which the shell  35  is fasted. The electric motor  32  is fixedly mounted on the base  36 , covered by the shell  35 , and electrically connected with a battery unit  14 , which is disposed under the deck of the boat  10  as shown in  FIG. 2 . Through a coupling  342 , a top end of the first transmission shaft  34  is connected with an output shaft  322  of the motor  32  in such a way that the first transmission shaft  34  extends vertically and downwardly relative to the motor housing  31  and is driven to rotate by the output shaft  322 . In addition, the bottom end of the first transmission shaft  34  is provided with a first gear  37 . 
     The mounting bracket  40  is composed of a mounting collar  41 , a needle roller bearing  42 , two links  43 , a hanger  44  and a tightening bolt  45 . The mounting collar  41  is sleeved onto the base  36  of the motor housing  31  in such a way that the needle roller bearing  42  is disposed between the mounting collar  41  and the base  36  of the motor housing  31 . In this way, the driving device  30  is rotatable relative to the mounting bracket  40 . Each of the two links  43  has a first end pivotally connected to one of two opposite sides of the mounting collar  41 . The hanger  44  has a top edge pivotally connected with the mounting collar  41  and a bottom edge pivotally connected with a second end of each of the links  43 . A front portion of the hanger  44  is bent to form a hanging rack  422  for being hung on the transom  12  of the boat  10 . The tightening bolt  45  is screwingly inserted into the hanging rack  442  and has a free end for stopping at the transom  12  of the boat  10  to therefore fix the hanger  40 . 
     The propelling device  50  is composed of a fluid guiding member  51 , a second transmission shaft  52  and a propeller  53 . The bottom end of the first transmission shaft  34  is inserted into the fluid guiding member  51  in such a way that a needle roller bearing  54  is disposed between the first transmission shaft  34  and the fluid guiding member  51 . The second transmission shaft  52  is transversely and rotatably disposed in the fluid guiding member  51  and provided with a front end having a second gear  55  engaged with the first gear  37 , and a rear end extending out of the fluid guiding member  51  and being connected with the propeller  53  in such a way that the first transmission shaft  34  is substantially perpendicular to the second transmission shaft  52 . By means of the engagement of the first gear  37  with the second gear  55 , the second transmission shaft  52  can be driven by the actuation of the first transmission shaft  34  to rotate, which in turn can drive the propeller  53  to rotate. 
     The connecting tube  60  is an aluminum-extruding tube and connected between the base  36  of the motor housing  31  of the driving device  30  and the fluid guiding member  51  of the propelling device  50  in such a way that the connecting tube  60  houses the first transmission shaft  34 . The connecting tube  60  can enhance the overall structural strength of the electric outboard drive. 
     When the electric motor  32  is started, the first transmission shaft  34  is driven by the output shaft  322  to rotate, which in turn drives the second transmission shaft  52  to synchronously rotate due to the engagement of the first gear  37  with the second gear  55 , which in turn drives the propeller  53  to rotate so as to propel the boat forward. If the electric motor  32  runs reversely, the boat will sail backward. In addition, the electric outboard drive  20  is further equipped with a tiller  70  having an end mounted to the base  36  of the motor housing  31  for turning the driving device  30  leftward or rightward, as shown in  FIGS. 5-7 . When the tiller  70  is turned by a user, because the motor housing  31  of the driving device  30 , the connecting tube  60  and the fluid guiding member  51  of propelling device  50  are connected with each other, the propeller  53  of the propelling device  50  will be synchronously revolved about the center axis of the mounting collar  41  so as to effect the steering control of the boat  10 . 
     As indicated above, the electric outboard drive  20  of the present invention has the advantages as follows. 
     1. Utilizing the electric motor  32  as the propulsion power makes the electric outboard drive  20  of the present invention have a light weight and a low pollution so as to meet the environmental protection requirement. Because of the lightweight design, the electric outboard drive  20  of the present invention can be conveniently detached from the boat  10  for transportation and/or storage so as to minimize the risk of being stolen. 
     2. The steering control of the boat  10  can be effected by a tiller  70  having a simple structure, which simplifies the overall construction of the outboard drive of the present invention. 
     3. The installation location of the battery unit  14  can be adjusted according to an actual need to shift the center of gravity of the boat. In addition, since the electric motor that can be used in the electric outboard drive present will not be limited by the available space of the electric outboard drive, various specifications of the electric motors can be chosen subject to the size of the boat for providing sufficient propulsion power to the boat. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.