Abstract:
A marine articulated surface drive propulsion system is provided with a housing construction that allows the direct application of an electric motor for power onto the drive structure. Alternatively, it can include a power transmitting element for reducing the rate of rotation or the position of the motor shaft with respect to the propeller shaft. The drive can be retrofitted to existing boat hulls and does not require a dedicated hull. The electric motor can be fitted to the surface drive housing on the inside of the transom. It is contemplated that an electric motor with very small dimensions can be mounted in the drive thrust tube and ball socket, eliminating the need for U joints. Notably, if the propeller is left free wheeling it becomes the propulser for the electric motor to become a generator and recharge the batteries.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention pertains to a marine propulsion system, and more particularly the present invention pertains to improvements to an environmentally friendly surface drive marine propulsion system. 
         [0003]    2. Discussion of the Related Art 
         [0004]    In light of numerous environmental concerns, vehicles that can be powered with electrical power instead of relying on internal combustion engines are becoming increasingly popular. To date, the most prevalent commercialized examples of this trend are found in the automobile industry. 
         [0005]    Some efforts have been made to utilize electric power drive technologies in the marine industry, but none that incorporate surface drives. Surface drives of all configurations have existed for some time, see, e.g., U.S. Pat. No. 4,645,463 to Arneson, which is expressly incorporated by reference herein. 
         [0006]    The use of an electrical motor as the power source to the propeller has also existed, especially in naval vessels. However, the most prevalent marine examples of electric motor usage have been implemented in hybrid electric-combustion systems in the largest of marine vessels and in electric trolling motors for small vessels, but none of these marine vehicles incorporate an electric motor powering a surface drive. 
         [0007]    Large pleasure boats or other boats may operate at lower speeds to avoid wakes and noise when at or near marinas, other mooring locations, or when traversing a no-wake designated portion of a waterway. Importantly, electric motors are more fuel efficient than combustion engines at lower speeds and benefit from reduced noise and non-existent exhaust emission when compared to combustion engines as well. 
         [0008]    It is further noted that in various jurisdictions, anti-idling rules and regulations are being proposed and implemented for boats and other watercraft. Some jurisdictions are proposing and implementing rules and regulations that prohibit the use of internal combustion engines, or establish maximum horsepower ratings for internal combustion engines, for certain portions of the waterways in these jurisdictions. 
         [0009]    The current surface drive systems fail to provide a solution to the problem of fuel overconsumption by and emissions from internal combustion engine powered boats. Known surface drives are driven by internal combustion engines which are both heavy and noisy. 
         [0010]    A green solution was desired that would create less environmental pollution in the form of decreased noise and exhaust emission and improved fuel efficiency. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a marine surface drive system that yields reduced noise and air pollution emissions utilizing an engine that is an electric motor. In some embodiments the electric motor can be configured as a generator. 
         [0012]    In recent years battery technology has developed rapidly to the point where the stored energy densities of some batteries make electric propulsion of marine vessels possible. Further, advances in semiconductor switching technology enable numerous electric motor improvements, such as reduced size, that would not have been possible in the past. The propulsion power of the present invention is provided by an electric motor that can be mounted directly and integrally to the inside housing of the surface drive system. Alternatively, there could be reduction gearing between the electric motor and the surface drive input shaft. It is contemplated that when technology will allow significantly reduced electric motor dimensions, the electric motor can be mounted in the socket ball of the surface drive thrust tube eliminating the coupling having universal joints. 
         [0013]    The electric motor may be inboard or outboard. The electric motor may directly turn the propeller at the same rate of revolutions per minute as the shaft of the electric motor. In another preferred embodiment, the electric motor may be connected to a transmission wherein the revolutions per minute of the motor are reduced such that the propeller turns at a slower RPM than the shaft of the electric motor. 
         [0014]    Accordingly, it is an object of the present invention to provide an electric marine surface drive system that can propel a boat with an electric motor, preferably for an extended period of time. Preferably, the marine propulsion system will take advantage of new battery and electric motor technology, as well as the anticipated introduction of cost effective fuel cells as energy sources for marine propulsion systems. Another object of this invention is to provide a marine propulsion system that is highly compact, flexible as to where it is mounted and still highly efficient and quiet. Thus, to the preferred embodiments provide an electric marine surface drive system that can be installed in an engine compartment which is smaller or substantially the same size as a typical engine compartment that houses a conventional internal combustion engine power train system. It is also an object of this invention to offer an integral electric propulsion system which may act as a generator and recharge its batteries. 
         [0015]    According to a preferred embodiment, a surface drive for a marine vehicle includes a support housing and at least one propeller wherein a portion of the propeller is above a water surface thereby substantially reducing underwater drag. In addition, the surface drive has at least one electric motor coupled to at least one propeller, the motor including a motor control device for actuating the electric motor and selecting a electric motor speed and a rotation direction. Further, at least one shaft that couples the electric motor to the propeller, and a shaft carrier are provided, wherein at least a portion of the at least one shaft extends through the shaft carrier. 
         [0016]    In another embodiment, at least one electric motor is mounted within the support housing. 
         [0017]    According to a further aspect of this embodiment, at least one shaft includes a drive shaft and a propeller shaft, and the electric motor is attached to the drive shaft that is coupled to the propeller shaft. Moreover, at least one propeller is coupled to the propeller shaft. 
         [0018]    In another aspect of this embodiment, the drive further includes an articulated trimming arm having an adjustable length and at least one movable joint at an arm end with an arm forward end connecting to the marine vehicle and an arm rear end connected to about the top of the shaft carrier such that the arm is substantially parallel to and above a shaft long axis. The articulated trimming arm may be lengthened or shortened thereby rotating the ball joint substantially downwards and upwards, respectively, thereby controlling a portion of the propeller that is submerged and a depth of submersion. 
         [0019]    In yet another aspect of this embodiment, the drive further includes at least one articulated steering arm having an adjustable length and at least one movable joint at an arm end with an arm rear end connecting to about the side of the shaft carrier and an arm forward end connected forward of a pivot point of the ball joint so that the arm forward end is at least substantially horizontally displaced from the shaft long axis. In this case, the articulated steering arm may be lengthened or shortened thereby rotating the ball joint to either side controlling the horizontal angle of the propeller shaft relative to the marine vehicle for steering. 
         [0020]    According to another aspect of this embodiment, the shaft includes at least a forward drive shaft and a propeller shaft with a power transmission unit there between. The power transmission transmits rotational movement from the forward drive shaft to the propeller shaft with at least one of the following: a reduced rotational speed of the propeller shaft or a displacement between the rotational axes of the forward drive shaft and the propeller shaft. 
         [0021]    According to another preferred embodiment, a surface drive for a marine vehicle includes a support housing securably mounted to the marine vehicle. Additionally, the surface drive has at least one electric motor by which the at least one propeller is drivable. The motor having a control device for actuating the electric motor and selecting a electric motor speed and a rotation direction, and an electric power source. The drive also includes at least one propeller, wherein the position of the propeller with respect to the marine vehicle is vertically controllable such that a portion of the propeller may be above a water surface thereby substantially reducing underwater drag. In addition, the position of the propeller with respect to the marine vehicle is horizontally controllable to steer the direction of the marine vehicle. In addition, the drive has at least one shaft having a forward end connected to the electric motor, a rear end connected to the propeller, and a shaft carrier. 
         [0022]    In another aspect of this embodiment, the drive of the electric motor is securably mounted in one of a group including a support housing and the shaft carrier. 
         [0023]    These and other aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description while indicating preferred embodiments of the present invention is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
           [0025]      FIG. 1  is a side elevational view of an embodiment of the marine surface drive apparatus of the present invention; 
           [0026]      FIG. 2  is a sectional side view of a section of the embodiment of  FIG. 1 ; 
           [0027]      FIG. 3  is a perspective view of another embodiment of the marine surface drive apparatus of the current invention having steering cylinders; 
           [0028]      FIG. 4  is a fragmentary top plan view of another embodiment of the marine surface drive apparatus of the current invention having steering cylinders mounted to the support casing; 
           [0029]      FIG. 5  is a perspective view of another embodiment of the marine surface drive apparatus of the current invention having steering cylinders mounted to the transom of the marine vessel and showing hydraulic fluid conduits; 
           [0030]      FIG. 6  is a schematic view of the steering and trim control system for the apparatus of the preferred embodiments; 
           [0031]      FIG. 7  is a perspective view of another embodiment of the marine surface drive apparatus of the current invention having a single steering cylinder mounted to the transom of the marine vessel; 
           [0032]      FIG. 8  is a side elevational view of another embodiment of the marine surface drive apparatus of the present invention having a power transmission apparatus; 
           [0033]      FIG. 9  is a side elevational view of another embodiment of the marine surface drive apparatus of the present invention having an internal electric motor; 
           [0034]      FIG. 10  is a side elevational view of another embodiment of the marine surface drive apparatus of the present invention having an integral electric motor within the housing ball joint; 
           [0035]      FIG. 11  is a vertical sectional side view taken along the long axis of the apparatus of  FIG. 9  showing the mounting of the electric motor with the housing ball joint; 
           [0036]      FIG. 12  is a block diagram showing the electric motor control system according to a preferred embodiment; and 
           [0037]      FIG. 13  is a block diagram showing the electric charging system according to a preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    With reference to the drawings, and particularly to  FIGS. 1 and 2 , there is shown a first embodiment of the electric marine surface drive apparatus  10  adapted for use with a marine vehicle having a transom  20  upon which the apparatus  10  is mounted or integrated. Drive  10  includes a support housing, such as the tubular support casing  22  secured to transom  20 , having at its rear end a ball socket  24  ( FIG. 2 ) preferably formed of a synthetic plastic, such as nylon. A propeller shaft  40  is journaled by bearings  45 ,  47 ,  49  in propeller shaft carrier  30 . The rear end of the propeller shaft  40  receives propeller  44 , for example a conventional surface-piercing propeller. The propeller shaft carrier  30 , for example a tubular propeller shaft carrier, comprises a ball  32  at its front end which is pivotally mounted in the ball socket  24  (collectively, a ball joint  25 ) as shown in  FIG. 2 , and a propeller shaft housing  74  connected to the ball socket  24  at the shaft carrier  30  rear end. The propeller shaft housing is preferably frusto-conical. Ball joint  25  allows the angle of the propeller  44  relative to the marine vehicle to be changed to either affect the marine vehicle speed or direction. 
         [0039]    A forward drive shaft  38  is journaled by bearings  54 ,  56  in support casing  22 . The forward drive shaft  38  comprises a front end connected to an inboard electric motor  11  as shown in  FIG. 1 , and a rear end connected to a universal joint  46 , preferably a conventional double universal or constant speed joint, as shown in  FIG. 2 . The electric engine  11  may be any conventional electric motor such as any appropriate horsepower AC or DC electric motor, or for example, an HTS technology super conductor motor. 
         [0040]    The universal joint  46  couples the rear of the drive shaft  38  with the front of propeller shaft  40  such that the propeller shaft  40  rotates at the same rate as the forward drive shaft  38  while allowing an angular displacement of the propeller shaft long axis from the drive shaft long axis in one or more directions. This angular displacement occurs when the ball joint  25  rotates or pivots, which is to say that ball  32  pivots relative to ball socket  24  about pivot point  50 . In other words, the center of universal joint  46  corresponds to the pivot point  50 . 
         [0041]    Support housing  22  has a rear main body  51  having an open rear end. The rear main body  51  is integral or connected to a front end body  52 . Front end body  52  extends through transom  20  and has an open front end. Preferably both the rear main body  51  and the front end body  52  are substantially cylindrical as shown in  FIGS. 1 and 2 . Support casing  22  is rigidly affixed to the rear surface of transom  20  by a plurality of bolts  62 . A stabilizing fin  90  is secured or integral to propeller shaft housing  74 . The stabilizing fin  90  acts to help counter the lift of the propeller shaft while the boat is turning. 
         [0042]    In addition, embodiment  10  of  FIGS. 1 and 2  shows trim assembly  141  for vertical control (i.e. raising and lowering the drive) to control the portion of the propeller that is above the water thereby controlling drag and thrust. Trim assembly  141  is pivotally attached to housing  74  by vertical ear  154  and bracket  152 , which is affixed to the end of piston rod  142  and shiftably coupled to of power-operated hydraulic trim cylinder  140 . Trim assembly  141  has ball joint member  144  for insertion into ball receiving socket  145  contained within socket assembly  146  affixed to the transom  20  with bolts  151 . 
         [0043]    Referring to  FIG. 3 , another preferred embodiment  200  has steering assemblies  117 ,  119  which attach to ears  100 ,  102  extending laterally from the housing  74 . The ears  100 ,  102  are pivotally connected to brackets  107 ,  103  affixed to the ends of piston rods  104 ,  106  shiftably coupled to power-operated hydraulic steering cylinder  108 ,  110 , respectively. Steering assemblies  117 ,  119  have ball joint members  112 ,  114  for insertion into ball receiving sockets (not shown) affixed to the transom. In addition, embodiment  200  of  FIG. 3  has a trim assembly such as trim assembly  141  first shown in  FIGS. 1 and 2 , for raising and lowering the drive. Trim assembly  141  is pivotally attached to housing  74  by vertical ear  154  and bracket  152 , which is affixed to the end of piston rod  142  and shiftably coupled to power-operated hydraulic trim cylinder  140 . Trim assembly  141  has ball joint member  144  for insertion into ball receiving socket affixed to the transom. The operation of the trim assembly  141  rotatably raises the drive when piston rod  142  is retracted into hydraulic cylinder  140  and rotatably lowers the drive when piston rod  142  is extended from hydraulic cylinder  140  with both movements primarily rotating the ball joint  25 . 
         [0044]    Referring to  FIG. 4 , preferred embodiment  210  has two articulated steering assemblies  117 ,  119  with adjustable length such as hydraulic steering cylinders  108 ,  110 . The steering arms  117 ,  119  have respective movable ball and socket joints  111 , 113 . The forward ends of steering cylinders  108 ,  110  are provided with ball pivots  112  and  114 , respectively, rotatably received within complimentary recesses  116  and  118  formed in a pair of mounts  120  and  122 . Another aspect of this preferred embodiment is that the mounts  120 ,  122  may be attached or integral with support casing  22 . With reference to  FIG. 5 , in another preferred embodiment  220  the mounts  120 ,  122  are secured to transom  20  rather than the support casing  22  to alleviate some stress from casing  22 . 
         [0045]    Continuing with  FIG. 5 , the embodiment  220  has a hydraulic system whereby the front and rear portions of steering cylinders  108  and  110  are provided with fluid conduits  130 ,  131  and  132 ,  133 , respectively. The fluid conduits are in communication with conventional hydraulic steering system  190  shown in  FIG. 6  described further below. Referring again to  FIG. 5 , an articulated trimming arm  141  has fluid conduits  158 ,  160  which are in communication with, for example, a conventional hydraulic trimming system  192  shown in  FIG. 6 . 
         [0046]    Referring to  FIG. 5 , the front end of the trim cylinder  140  is provided with a ball pivot  144  pivotally received within a socket  145  of a mount secured to transom  20  by fasteners  151 . The rear end of trim arm  141  is provided with a bifurcated bracket  152  which straddles an upwardly extending pad  154  rigidly affixed to the upper, intermediate portion of tube  74 . A pivot pin  156  interconnects bracket  152  and pad  154 . Hydraulic conduits  158  and  160  connect the front and rear ends of trim cylinder  140  with the hydraulic system shown in  FIG. 6 . 
         [0047]    Referring now primarily to  FIG. 6 , the hydraulic system includes a conventional power source  180 , coupled to a hydraulic pump  181 . A reservoir  182 , and conventional control valves  184  and  186  are coupled to pump  181 . In one preferred embodiment, steering cylinders  108  and  110  and trim cylinder  140  are connected to valves  184  and  186 , respectively, by conduits  130 ,  131 ,  132 ,  133 ,  158  and  160 . Valve  184  is operatively connected to a steering wheel  190  of the boat in a conventional manner while valve  186  is operatively connected to an up-down trim lever  192  in a conventional manner. Rotation of steering wheel  190  will operate valve  184  so as to control the flow of pressurized hydraulic fluid from pump  181  to steering cylinders  108  and  110 . In this manner, piston rods  104  and  106  of the steering cylinders will be concurrently extended and retracted, respectively. Referring to  FIG. 3 , the extension and retraction of steering cylinders  108  or  110  provide horizontal control of drive  200  by swinging propeller shaft carrier  30  laterally about a steering axis S-S which also pivots ball joint  25  laterally about axis S-S. In addition, pivot point  164  of ball pivot  144  lies on steering axis S-S such that the lateral movement about axis S-S pivots trim arm  141  laterally. In another preferred embodiment  230 , there is only a single steering cylinder  161 , for example, as shown in  FIG. 7 . In yet another preferred embodiment, valve  186  of  FIG. 6  may be connected to an automated trim controller, which may be used rather than, or in addition to, the manual up-down trim lever  192  of  FIG. 6 . 
         [0048]    Next, turning to  FIG. 8 , in another preferred embodiment, a drive  240  includes a drive shaft  38  that may be coupled to any conventional power transfer apparatus such as, for example, the power transmission unit  61  rather than coupled directly to the electric motor  11  as shown in  FIG. 1 . Power transmission  61  of drive  240  of  FIG. 8  allows for displacement D between the input shaft  39  axis “I” and the output shaft  38  axis “O.” Power transmission  61  may rotate the output shaft  38  at a reduced velocity from the input shaft  39 . Still referring to  FIG. 8 , power transmission unit  61  of drive  240  has a gear  65  connected to the input shaft  39  and a gear  63  connected to the rear shaft portion, wherein the gears could be spur gears, planetary gears, helical gears, herringbone gears, straight bevel gears, spiral bevel gears, hypoid gears, worm gears, and may alternatively include a chain or toothed belt drive. Electric motor  11  turns shaft  39  causing gear  65  to turn intermediate shaft  66 , which causes gear  63  to rotate output propeller shaft  40  and propeller  44 . 
         [0049]    Electric motor II of the preferred embodiment may be inboard as shown in  FIG. 1 . In alternative embodiments, the electric motor may be outboard and contained within the support housing  22  in a position that is forward of the ball socket  24  as shown in  FIG. 9 . Drive  250  includes an electric motor  252  that is secured to transom  20 , either directly or indirectly. 
         [0050]    In another alternative shown in  FIGS. 10 and 11 , a drive  260  includes an electric motor  262  that is positioned within support housing  22  and within ball socket  24 . In this case, electric motor  262  is free to move with respect to housing  22  as ball joint  25  is rotated, while staying rigidly affixed to propeller shaft  40 . This mounting position allows motor  262  to be connected directly or indirectly to propeller shaft  40  without an intervening universal joint  46  ( FIG. 2 ). 
         [0051]    Referring primarily now to  FIG. 12 , electric motor  11  requires an electrical power source  204 , which may comprise electrical storage devices such as batteries or capacitors; controls  206  for the speed and direction of the marine vessel; and a motor drive unit  208 . Motor drive unit  208  has connections  216  to a power source  204 , one or more control signals from motor control device  214 , and connections to the electric motor  210 . The connections to electric motor  210  comprise output motor control signals which power the electrical motor  11  to rotate electric motor shaft  212  at a commanded electric motor speed “v” having a rotational velocity and a clockwise or a counterclockwise rotation direction corresponding to forward and reverse directions commanded by speed and direction control signals from the motor control device  206 . 
         [0052]    In another preferred embodiment the connections  210  from motor drive  208  to electric motor  11  may also include inputs indicating the velocity and direction of rotation of the electric motor  11 . Another preferred embodiment may also include one or more signals indicating the marine vessel speed and direction. Another embodiment includes a neutral setting of the motor control device  206  where no electric power is provided to the electric motor  11  thereby ceasing rotation. 
         [0053]    Now turning to  FIG. 13 , in one preferred embodiment, rotation “A” of the propeller  44  by another source of power, such as water current, creates some rotation “B” in the electric motor  11 . This rotation causes the electric motor  11  to generate one or more electric currents  224  which inverter  222  utilizes to provide electric current  226  to charge the electrical power storage device  220 . In one preferred embodiment, the electric motor produces 3-phase AC currents  224 , and the inverter  222  produces a direct current  226  to charge a storage device, such as a lead-acid battery  220 . The electrical storage device  220  provides electrical power to motor  11  and, in another preferred embodiment, the power source  180  for hydraulic pump  181  ( FIG. 6 ) has electrical power supplied by electrical storage device  220 . 
         [0054]    It is noted that many changes and modifications may be made to the present invention without departing from the spirit thereof. The scope of some of these changes is discussed above. The scope of others will become apparent from the appended claims.