Abstract:
An electrically driven power system includes a carrier structure rotatably supporting a power output. A plurality of individually electrically powered primary drive units are also mounted in the carrier structure. Each of the power units are in driving engagement with the power output for driving said power output in a rotating manner. The electric motors driving the power units are interchangeable thus eliminating a single point motor failure and their smaller size facilitates ease of replacement and repair.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to electric propulsion systems and more particularly to a propulsion system powered by a plurality of electric motors. 
   2. Discussion of the Related Art 
   For over a century, internal combustion engines have been a mainstay of portable or mobile propulsion systems. These engines have powered everything from automobiles to watercraft to airplanes. Additionally, these internal combustion engines have also been used to power various configurations of stationary machinery. In short, much of a person&#39;s everyday life is impacted by powered machines that are directly or indirectly linked to internal combustion engines. 
   Internal combustion engines possess many disadvantages. First, they are quite noisy and require substantial noise insulation if located in proximity to areas inhabited by humans for even brief periods of time. Further, internal combustion engines utilize fossil fuels that are pollutants if spilled or not handled in a correct manner. The combustion byproducts are also pollutants by injecting excess carbon dioxide, carbon monoxide, nitrous oxides, and forms of sulfur into the atmosphere. While strides have been made to reduce these pollutants, they will always be present in some quantity as a result of the burning of the fuel. 
   The majority of vehicles are powered by internal combustion engines and most often by a single internal combustion engine. Internal combustion engines are also inherently inefficient and thus require a substantial housing space with associated ventilation and insulation requirements. Even though the reliability of internal combustion engines has improved dramatically over the years, most vehicles are powered by only a single engine. The engine thus represents a single point of failure which can have disastrous and even life threatening results in the event of the engine failing. Further, in the event of a massive failure of the engine requiring its replacement, instead of the repair of a component, the engine must be removed from the vehicle. Often, this poses a very difficult and time-consuming effort resulting in considerable expense and downtime for the vehicle. 
   One solution has been the replacement of the internal combustion engine with an electric motor. However, electric motors also have some of the same disadvantages as the internal combustion engine. Typically, a single motor is used to provide driving power to each power output such as a single motor to drive each wheel of a car or the propeller of a watercraft. In those applications where a significant power output is required, a very large electric motor is required to provide such power. Again, a single motor equates to a single failure point. Additionally, as the power requirement increases, the size and weight of the electric motor also increases resulting in many of the same housing and replacement problems as an internal combustion engine. 
   Thus what is desired is an electric propulsion system that minimizes the probability of a single point failure while simultaneously being space adaptable and easy to repair and maintain. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to an electrically driven power system that satisfies the need to minimize single point failures and is yet space adaptable and easy to maintain and repair. The electrically driven power system includes a carrier structure rotatably supporting a power output. A plurality of individually electrically powered primary drive units are also mounted in the carrier structure. Each of the power units are in driving engagement with the power output for driving said power output in a rotating manner. 
   Another aspect of the present invention is an electrically driven power system for providing a rotational power output including a carrier structure rotatably supporting a power output. An electrically powered primary drive unit is mounted in the carrier structure and is in driving engagement with the power output for driving the power output in a rotating manner. Additionally a plurality of individually electrically powered secondary drive units are mounted in the carrier structure such that each of the secondary power units are in driving engagement with the primary drive unit for augmenting the primary drive unit in driving the power output in a rotating manner. 
   Yet another aspect of the present invention is an electrically driven power system for providing a rotational power output. The power system includes a first carrier plate affixed to a second carrier plate in a substantially parallel spaced apart manner defining a gear space therebetween. A sun gear and at least one primary planet gear are supported in the gear space in a like manner such that the primary planet gear is intermeshed with the sun gear. At least one secondary planet gear is also supported in the gear space and intermeshed with the primary planet gear. An electric motor is drivably coupled to each primary planet gear and the secondary planet gear for providing power to the sun gear. 
   A further aspect of the present invention is an electrically driven power system for providing a rotational power output that includes a first carrier plate affixed to a second carrier plate in a substantially parallel spaced apart manner defining a gear space therebetween. A sun gear and a plurality of primary planet gears are rotatably supported in the gear space such that each primary plant gear independently meshes with the sun gear to permit the rotation of the sun gear. An electric motor is drivably coupled to each primary planet gears for providing individual power to each of the primary planet gears. 
   The planet gears can also be coupled to two axially aligned electric motors. The system is thus powered by a plurality of substantially identical motors that are interchangeable one with the others. 
   These and other features, aspects, and advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a general perspective view of a watercraft embodying the present invention; 
       FIG. 2  is a cross-sectional elevation view of the watercraft shown in  FIG. 1  and taken along the lines  2 - 2 ,  FIG. 1  showing an electric gear driven propulsion system employed to power the watercraft; 
       FIG. 3  is perspective view of the electric gear driven propulsion system; 
       FIG. 4  is a side elevation view of the electric gear driven propulsion system of  FIG. 3 ; 
       FIG. 5  is an elevational cross-section view of the electric gear driven propulsion system shown in  FIG. 4  taken along the lines  5 - 5 ,  FIG. 4 ; 
       FIG. 6  is an elevation cross-sectional view of an individual drive assembly mounted in the carrier and taken along the lines  6 - 6 ,  FIG. 5 ; 
       FIG. 7  is an electrical schematic illustrating the wiring scheme for powering the propulsion system; and 
       FIG. 8  is an alternate gearing configuration illustrating the adaptability of the electric gear driven propulsion system. 
   

   Like reference numerals refer to like parts throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   For purposes of description herein, the terms “upper”, “lower”, “left”, “rear”, “right”, “front”, “vertical”, “horizontal”, and derivatives thereof shall relate to the invention as oriented in  FIG. 3 . However, one will understand that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
   Turning to the drawings,  FIGS. 1 and 2  show a boat  10  incorporating an electrically driven power system  20  which is one of the preferred embodiments of the present invention and illustrates its various components which include planet gears  30 ,  32  (driven by a plurality of electric motors  38  receiving electric power from electric wires  46 ,  48 ,  FIG. 3 ) engaged with sun gear  36  for rotating output shaft  40  for providing propulsive power to boat  10 . Power system  20  can be a primary source of propulsion in a powerboat, or an alternative propulsion source for a sailboat  10  as shown in  FIG. 1 . 
   Turning to  FIGS. 3-6 , one configuration of electrically driven power system  20  is illustrated wherein a carrier structure  22  comprises a first carrier plate  24  and a second carrier plate  26  affixed one to the other by a plurality of standoffs  28 . Standoffs  28  maintain first and second carrier plates  24 ,  26  in a spaced apart and substantially parallel relationship and define a gear space  25  therebetween. Carrier plates  24 ,  26  require no predefined geometric configuration and can be modified or tailored to conform to the space constraints of the parent structure in which electrically driven power system  20  is installed. Alternatively, carrier structure  22  can comprise an enclosed housing defining gear space  25 . An enclosed carrier structure  22  additionally facilitates the retention of gear lubricant in proximity to gears  30 ,  32 ,  36 . 
   Thus, electrically driven power system  20  can be geometrically configured to fit the application rather than tailoring the application to receive a predefined volume such as an internal combustion engine. This is especially advantageous in such applications as a marine craft wherein the shape of the application, i.e. boat hull, can be optimized for performance in the water and efficient use of space rather than compromised to receive a large internal combustion engine. The triangular configuration of carrier structure  22  is illustrative only and those skilled in the art will appreciate that the geometry of carrier  22  can assume infinite geometries as dictated by the parent structure in which it is to be installed. 
   As most clearly illustrated in  FIGS. 3 and 4 , a sun gear  36  is positioned in gear space  25  between first and second carrier plates  24 ,  26  and is affixed to power output shaft  40 . Power output shaft  40  is rotatably supported in first and second carrier plates  24 ,  26  by bearings  37  and extends from carrier structure  22 . Power output shaft can terminate with a coupler  42  for engaging a propulsive device such as a propeller or other device such as a pulley or gear for further transference of power generated by electrically generated power system  20 . 
   A plurality of drive units  60  are mounted and rotatably supported in carrier structure  22  in a manner such that the power generated by each of drive units  60  are combined for transference to sun gear  36 .  FIG. 6  illustrates a sample drive unit  60 . Each drive unit  60  includes a planet gear  30  when a drive unit  60  is utilized as a primary drive or a planet gear  32  when a drive unit  60  is utilized as a secondary drive (as shown). Planet gears  30 ,  32  include a plurality of teeth around its periphery for intermeshing with the teeth of sun gear  36  and other planet gears  30 ,  32  in a manner well known in the art. Those practiced in the art will readily recognize that the diameters of sun gear  36  and planet gears  30 ,  32  can be set at a desired ratio at the design stage of power system  20  to provide the desired torque or rotational speed of output shaft  40 . 
   Planet gear  32  defines an axis of rotation  29  on which are located a pair of electric motors  28 . Electric motors  38  are coupled to planet gear  30  or  32  with motor shaft  44 . Planet gears  30 ,  32  can be affixed to shafts  44  by utilizing set screws  46  through gear hub  33  to bear on shaft  44  to maintain planet gears  30 ,  32  in a fixed relationship to shafts  44  and to thus rotate in concert with shafts  44 . Electric motors  38  include wiring terminals A and B (here designated by  72 ,  74 ,  FIG. 4 ) for the connection of live conductor  52  and neutral conductor  54  to deliver electrical power to electric motors  38  (the wiring schematic is illustrated in  FIG. 7  and discussed below). While drive unit  60 , as illustrated, incorporates two axially aligned electric motors  38 , one of the motors  38  can optionally be deleted from a particular drive unit to conform to space constraints of the structure in which electrically driven power system  20  is housed. Thus, the total power required of power system  20  is satisfied by incorporating the necessary number of individual drive units  60 , which is a direct function of the number of electric motors  38 . If one particular drive unit  60  can only employ one electric motor  38 , the total power output of system  20  can be maintained by the inclusion of an additional drive unit  60  with one or two electric motors  38 . 
   Each of the individual drive units  60  are mounted in carrier structure  22  such that planet gears  30 ,  32  are substantially co-planar with sun gear  36  in gear space  25 . Electric motors  38  are affixed to first and second carrier plates  24 ,  26  in a fixed manner such as with fasteners  48  to prevent rotation of motors  38  with respect to carrier structure  22 . Shafts  44  can further be rotatably supported in carrier plates  24 ,  26  with bearings  34  to provide rotational stability to planet gears  30 ,  32 . 
   Referring now to  FIG. 5 , and for purposes of illustration, a primary planet gear  30  (and its associated drive unit  60 ) is defined as being in direct intermeshing engagement with sun gear  36 , and a secondary planet gear  32  (and its associated drive unit  60 ) is defined as being in direct intermeshing engagement with a primary planet gear  30  or another secondary planet gear  32 . A primary planet gear  30  transmits the power obtained from its associated electric motors  38  by rotating according to directional arrow “D.” The next adjacent intermeshing secondary planet gears  32  transmit the power obtained from their associated electric motors  38  by rotating according to directional arrow “C.” In this manner the entire arrangement of sun gear  36 , primary planet gears  30 , and secondary plant gears  32  rotate in an intermeshing fashion to drive output shaft  40  in a desired rotational manner. 
     FIG. 7  illustrates the electrical configuration of the individual electrical motors  38  and corresponds to the physical configuration of power system  20  as shown in  FIG. 4 . Each electrical motor  38  has an “A” terminal  72  and a “B” terminal  74 . In order for both motors  38  of a drive unit  60  to power its associated planet gear  30 ,  32  in one direction, one of motors  38  must rotate clockwise and the other of motors  38  must rotate counterclockwise. Since, motors  38  are preferably identical for interchangeability purposes, the motors  38  must be electrically wired to provide the desired rotational direction of the motor  38 . As shown in  FIG. 7 , an electrical power supply  12  delivers live electrical power through live lead  16  with a corresponding neutral lead  18  to complete the power circuit. While the motors  38  could be hard wired to electrical power supply  12 , a plug  50  and receptacle  14  are most preferably utilized for convenient disconnection of electric power from power system  20 . Plug  50  is wired such that when connected to receptacle  14 , lead  52  becomes the live conductor and lead  54  becomes the neutral conductor. 
   In order to correctly drive electric motors  38 , live conductor  52  is connected to terminal “A” of the rightmost electric motor  38  associated with primary planet gear  30  and neutral conductor  54  is connected to terminal “B” of the motor  38  thereby rotating primary planet gear according to directional arrow “D” ( FIG. 5 ). Concurrently, live conductor  52  is connected to terminal “B” of the leftmost motor  38  associated with primary planet gear  30  and neutral conductor  54  is connected to terminal “A.” In this manner, motors  38  while identical, can simultaneously power primary planet gear  30  while oriented in axial opposition one to the other. In like manner, secondary planet gear  32  rotating oppositely to primary planet gear  30  (direction “C”,  FIG. 5 ), is electrically connected in reverse manner, i.e. the rightmost motor associated therewith has its terminal “B” connected to live conductor  52  and its terminal “A” connected to neutral conductor  54 . The leftmost motor  38  is thus likewise electrically connected in reverse manner. 
   While  FIG. 7  shows a typical wiring scheme representative of motors  38  being DC motors, electric power source  12  could also be an AC power supply with motors  38  being AC motors. Those practiced in the art will recognize that the wiring interconnecting power source  12  with motors  38  in an alternating current system can be modified from that shown to power motors  38  in the desired direction of rotation. 
   Alternatively, power system  20  can employ alternate means of power other than electricity, such as hydraulic power. In a configuration utilizing hydraulic power, power source  12  becomes a source of pressurized hydraulic fluid. Live conductor  52  in turn becomes a pressurized hydraulic supply line while neutral conductor  54  becomes a hydraulic fluid return line. The medium of energy transfer becomes hydraulic fluid flowing through the supply and return lines instead of electric current. Finally, motors  38  become hydraulic motors instead of electric motors. 
     FIG. 7  also illustrates each motor  38  as being hard wired to live conductor  52  and neutral conductor  54 . However, those practiced in the art will recognize that a plug and receptacle can be introduced between each motor  38  and conductors  52 ,  54  to facilitate the disconnection of a single motor  38  from electrical power supply  12 . 
   While  FIGS. 2-7  illustrate a power system  20  having one primary planet gear  30  in driving engagement with sun gear  36  and two secondary planet gears  32  in driving engagement with primary planet gear  30  thereby augmenting the driving power of primary planet gear  30 , other configurations are also contemplated. With reference to  FIG. 8 , one or more of the concepts illustrated can be incorporated to customize a power system to a particular need and configuration. A power output  140  such as a rotating shaft is coupled to sun gear  136 . Sun gear  136  can be driven by a plurality of primary planet gears  130  (each planet gear representing an associated drive unit  60 ). A primary planet gear  130  can independently drive sun gear  136  or can be augmented by one or more secondary planet gears  132 . One or more first secondary planet gears  132  engage a primary planet gear  130  to augment its power. One or more second secondary planet gears  132  can in turn engage a first secondary planet gear  132  to form a chain of secondary planet gears extending from a primary planet gear  130 . Thus, a specific application can incorporate in combination any number and arrangements of primary planet gears, first secondary planet gears, and second secondary planet gears with their associated motors to satisfy a particular power requirement. 
   In the instances where insufficient space is present to chain together a required number of drive units, two or more electrically driven power systems such as system  20  can be chained together in series along a common power output shaft to provide the required power demanded by the application. Those practiced in the art will recognize that the possible combinations and configurations of drive units  60  to comprise an electrically driven power system are infinite. 
   The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and are not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.