Abstract:
An axle drive apparatus includes a first rotor assembly with a first output shaft and a second rotor assembly with a second output shaft for providing independent rotation of the first and second output shafts. There also includes a first and second conductive assembly for, respectively, conducting electrical current into a inducing rotation of the first and the second rotor. Finally, an axial housing commonly connects the first and second rotor and the first and second brush card assembly. 
     A method of operating an axle drive apparatus includes supplying current to a first conductive and second conductive assembly, respectively, to conduct the current into and inducing rotation of a first and second rotor assembly. Then the axle drive is operated by engaging a first rotor assembly and a second rotor assembly, respectively, providing independent rotation of a first and a second output shaft.

Description:
FIELD OF THE INVENTION 
     The present invention relates to dual axles, and more particularly to dual drive axles, which are used, for example, in electric powered vehicles like wheelchairs. 
     BACKGROUND OF THE INVENTION 
     Manufacturers use two separate motors to improve maneuverability of electric powered vehicles or drive elements requiring independent control. For example, an electric lawn and garden tractor has independent electric motors for both driven wheels. The independent motors include separate reduction gearboxes and their wheels mounted on the output shaft of the gearboxes. The motors are controlled independently to allow each wheel to rotate at different speeds or in opposite directions. The power to the motors is controlled by an electric controller independent of the wheel, as to speed, with the power being increase or decreased in accordance with whether the wheels are under running or over running, relative to a manually-controlled speed setting. This allows a tight turning radius, that is, a zero turning radius when desired. 
     In electric motors the armature and commutator are generally spaced apart from each other axially along the motor shaft and wired in a manner to function as part of the motor. The armature is mounted to the motor shaft within a magnetic field. The armature is usually rotatably supported on the shaft by bearings. Consequently, a typical motor design includes one rotating armature. What is needed is an axle drive apparatus that is inexpensive to build with two separate armatures that independently rotate within one or two magnetic fields using a continuous common structure assembly. 
     SUMMARY OF THE INVENTION 
     It is an aspect of the claimed invention to provide an inexpensive axle apparatus with dual driven output shafts. 
     It is another aspect of the claimed invention to provide a dual drive axle apparatus sharing one or two magnetic fields. 
     It is yet another aspect of the claimed invention to provide a dual drive axle apparatus with two independently controlled armatures. 
     An axle drive apparatus includes a first rotor assembly with a first output shaft and a second rotor assembly with a second output shaft for providing independent rotation of the first and second output shafts. There also includes a first and second conductive assembly for, respectively, conducting electrical current into a inducing rotation of the first and the second rotor. Finally, an axial housing commonly connects the first and second rotor and the first and second brush card assembly. 
     A method of operating an axle drive apparatus includes supplying current to a first conductive and second conductive assembly, respectively, to conduct the current into and inducing rotation of a first and second rotor assembly. Then the axle drive is operated by engaging a first rotor assembly and a second rotor assembly, respectively, providing independent rotation of a first and a second output shaft. 
     These and other aspects of the invention will become apparent from the following description, the description being used to illustrate a preferred embodiments of the invention when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows individual components that are a part of the preferred embodiment of the invention. 
     FIG. 2 shows the assembly of the preferred embodiment of the invention. 
     FIG. 3 shows components of the preferred embodiment of the invention. 
     FIG. 4 shows an isometric drawing of the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the claimed invention is described below with reference to a wheel chair with dual drive, a practitioner in the art will recognize the principles of the claimed invention are viable to other applications. 
     In FIG. 4, a powered axle drive assembly, apparatus  40 , shows an isometric view of the preferred embodiment of the invention with the combination of the axle-drive housing  11 , the first gearbox  41 , and the second gearbox  42 . The first end  11   b  of axle-drive housing  11  communicates with a first end plate  31  that further communicates with the first gearbox  41 . The second end  11   c  of axle drive housing  11  communicate with a second end plate  32  that further communicates with a second gearbox  42 . Furthermore, the side of the first end plate  31  that touches the first end  11   b  is connected a first brush card assembly  12 , while the side of the second end plate  32  that touches the second end  11   c  is connected a second brush card assembly  24 . It is shown the first brush card assembly  12  and the second brush card assembly  24  project into the axle-drive housing  11  that allows them to be properly positioned and fitted to the axle-drive housing  11 . A second output shaft  43  rotates independent of a first output shaft  44 . Furthermore, the second output shaft  43  is capable of rotating in the opposition direction from the first output shaft  44 . Internally, as shown in FIG. 3, are the powered axle drive components allowing the independent rotation of the first output shaft  44  and the second output shaft  43 .. 
     Now referring to FIG. 1 it shows components  10   a  that are separate pieces of the preferred embodiment of the invention. The rotor assembly  15  and rotor assembly  16  fit into the magnet assembly  23  that further fit into axle-drive housing  11 . The components  10   a  are for a DC motor but are also available for AC motor applications with the required modifications. 
     The axle-drive housing  11  contains a first conductive brush card assembly recessed surface  12   a  on a first end  11   b , and a second conductive brush card assembly recessed surface  24   a  on a second end  11   c . This allows a first conductive brush card assembly  12 , and second conductive brush card assembly  24 , as shown in FIG. 4, to properly fit into axle-drive housing  11  when they are assembled in the housing The housing material is metal, plastic or molded resin depending upon the desired application. However, the preferred embodiment of the invention uses a metal axle-drive housing  11 . If a non-metallic axle-drive housing  11  is used, then it additionally contains a first metallic flux ring  25  and a second metallic flux ring  26 , communicating circumferentially with the inside of axle-drive housing  11 . The first metallic flux ring  25  and the second metallic flux ring  26  correspond, respectively, to a first magnet set  13  and a second magnet set  14 . As is known to the practitioner in the art the metallic flux ring is substituted for the loss of conduction present in the non-metallic axle-drive housing  11 . 
     The magnet assembly  23  includes magnet set  13  and magnet set  14  creating two independent magnetic fields. The magnets are a solid material and consist of one of the following: ceramic, samarium cobalt, neodymium iron boron, alnico, bonded ferrite, bonded neodymium, and bonded samarium cobalt. Furthermore, each magnet set includes a plurality of magnets and magnetic poles depending on the design criteria. Finally, the magnet assembly in another embodiment of the invention combines magnet set  13  and magnet set  14  into one set creating one magnetic field. 
     The first rotor assembly  15  includes a first co-axial armature core  20 , a first commutator  21  assembled on a first shaft  22 . The second rotor assembly  16  includes a second co-axial armature core  17 , a second commutator  18  assembled on a second shaft  19 . The rotor assemble  15  and rotor assembly  16  acts independently, receives separate independent signals from an external controller. The armature core and commutator are constructed as one skilled in the art would typically find in other DC motor applications. However, the armature core and commutator can be designed to work in AC motor applications. 
     FIG. 2 shows component  30   a  as designed for use in the preferred embodiment of the invention. The component  30   a  includes a first gearbox housing  41   a  that mounts with a second gearbox housing  41   b  of the first gearbox  41 , and a third gearbox housing  42   a  mounts with a fourth gearbox housing  42   b  of a second gearbox  42 . The first gearbox  41  has a first out put shaft  44 . The second gearbox  42  has a second output shaft  43 . The first gearbox housing  41   a  has securely connected a first end plate  31  that securely connects a first conductive brush card assembly  12 . The third gearbox housing  42   a  is securely connected to a second end plate  32  that securely connects a second brush card assembly  24 . The second gearbox housing  41   b , with its assembly, communicates with a first end  11   b  of axle-drive housing  11  that is shown in FIG.  1 . The fourth gearbox housing  42   b , with its assembly, communicates with a second end  11   c  of axle-drive housing  11  that is shown in FIG.  1 . 
     FIG. 3 shows axle drive apparatus  10  that is the assembly of the preferred embodiment of the invention, and include the assembly components  10   a  that are shown in FIG.  1 . The first magnet set  13  and the second magnet set  14  communicate with the internal surface  11   a  of axle-drive housing  11 . The first armature core  20 , of the first rotor assembly  15 , revolves within a first internal surface  13   a  of first magnet set  13 . The second armature core  17 , of the second rotor assembly  16 , revolves within a second internal surface  14   a  of the second magnet set  14 . 
     The first end  11   b  of axle-drive housing  11  is connected to a first gearbox  41  with a first armature shaft  22  inserted into the first gearbox  41 . The second end  11   c  of axle-drive housing  11  is connected to a second gearbox  42  with a second armature shaft  19  inserted into the second gearbox  42 . A first end plate  31  that mounts a first conductive brush card assembly  12  communicates with the first gearbox  41  and the first end  11   b  of axle-drive housing  11 . A second end plate  32  that mounts a second conductive brush card assembly  24  communicates with a second gearbox  42  and the second end  11   c  of axle-drive housing  11 . Furthermore, a first shaft bearing housing  49  securely connects a first bearing  46  that further rotatably connects to the first shat  22  second end  22   b . The first bearing housing  49  communicates with the internal surface  11   a  of axle-drive housing  11 . The second bearing housing  50  securely connects a second bearing  47  that further rotatably connects to the second shaft  19  fourth end  19   b . The second bearing housing  50  communicates with the internal surface  11   a  of axle-drive housing  11 . Finally, a first gearbox bearing  45  and a second gearbox bearing  45   a  rotatably secure the first shaft  22 , first end  22   a , to the first gearbox  41 . The third gearbox bearing  48  and a fourth gearbox bearing  48   a  rotatably secure the second shaft  19 , third end  19   a , to the second gearbox  42 . 
     The first conductive brush card assembly  12  is controlled independently from the second conductive brush card assembly  24 . The first rotor assembly is energized by the first conductive brush card assembly  12  that receives a first signal from an external controller. The second rotor assembly  16  is energized by the second conductive brush card assembly  24  that receives a second signal from an external controller. A practitioner in the art fully understands that each rotor assembly can be energized by a brush card containing multiple poles, or substituted for a conductive brushless card assembly, depending on the application. The preferred embodiment of the invention is a DC voltage design. However, AC line voltage is another option for axle drive apparatus  10 . 
     Independent control, along with the two magnetic fields, allows the building of a low-cost and efficient axle drive apparatus. The independent control of each rotor eliminates the need for separate motors in devices, for example, which require wheels to rotate at different speeds or different directions. The speed of the first rotor assembly  15  and the second rotor assembly  16  are increased/decreased by varying its voltage, which is supplied through independent signals from an external controller. The controller varies the direction of the rotation of the first rotor assembly  15  and second rotor assembly  16 , allowing one rotor assembly to rotate clockwise while the other rotor assembly rotates counter-clockwise or in a reverse direction. Furthermore, the external controller will vary the direction of the first and second rotor assembly allowing both to rotate clockwise or counter-clockwise at the same time. 
     The first gearbox bearing  45  and second gearbox bearing  45   a  are generally lubricated from gearbox grease internal to the first gearbox  41 . The third gearbox bearing  48  and fourth gearbox bearing  48   a  are generally lubricated from gearbox grease internal to the second gearbox. A practitioner in the art fully understands that with some modification to the gearbox design, gearbox oil is substituted for grease in different applications. 
     The first gearbox bearing  45 , of the first gearbox  41 , connects to the second gearbox housing  41   b  by a slip fit. The second gearbox bearing  45   a , of the first gearbox  41 , connects to the first gearbox housing  41   a  by a slip fit. The first end  22   a , of the first shaft  22 , connects to the first gearbox bearing  45  and to the second gearbox bearing  45   a  by interference fit. The second gearbox housing  41   b  is securely connected to the first end  11   b  of axle-drive housing  11 . The first gearbox housing  41   a  is connected to the second gearbox housing  41   b . The third gearbox bearing  48 , of the second gearbox  42 , connects to the fourth gearbox housing  42   b  by slip fit. The fourth gearbox bearing  48   a , of the second gearbox  42 , connects to the third gearbox housing  42   a  by a slip fit. The third end  19   a , of the second shaft  19  connects to the third gearbox bearing  48  and fourth gearbox bearing  48   a  by an interference fit. The fourth gearbox housing  42   b  is securely connected to the second end  11   c  of axle-drive housing  11 . Finally, the third gearbox housing  42   a  is connected to the fourth gearbox housing  42   b . A practitioner in the art fully understands that the first gearbox  41  and the second gearbox  42  are substitutable for other combinations including, but not limited to, pulleys with drive belts connected to the first shaft  22  and the second shaft  19 , and sprockets with drive chains connected to the first shaft  22  and the second shaft  19 . 
     The first bearing  46  and second bearing  47  are typically ball type bearings that are sealed requiring no additional lubrication. The bearings in other embodiments include, but are not limited to needle, roller, tapered, or self-aligning, depending on the application and duty requirements. The first bearing  46  is connected to a first bearing housing  49  by a slip fit. The second end  22   b , of the first shaft  22 , is connected to the first bearing  46  by an interference fit. The second bearing  47  is connected to the second bearing housing  50  by a slip fit. Furthermore, the fourth end  19   b , of the second shaft  19  is connected to the second bearing  47  by an interference fit. While the first bearing housing  49  and the second bearing housing  50  slip into axle-drive housing  11 , the first end plate  31  and second end plate  32  are securely connected to axle-drive housing  11 . In another embodiment of this invention the first bearing housing  49  and the second bearing housing  50  are securely connected to axle-drive housing  11 . 
     In FIG. 3 axle drive apparatus  10  is operated by engaging a first rotor assembly within a common magnetic field providing independent rotation when the magnet assembly and first rotor commutator are energized, and by engaging a second rotor assembly within a common magnetic field providing independent rotation when the magnet assembly and second rotor commutator are energized. Supplying a current to a first conductive brush in communication with a first rotor commutator energizes the first rotor. Supplying a current to a second conductive brush in communication with a second rotor commutator energizes the second rotor. Engaging a first brush card in an external controller to provide a first independent signal to the first conductive brush allows independent operation of the first rotor. Engaging a second brush card in an external controller to provide a second independent signal to the second conductive brush allows independent operation of the second rotor. 
     Referring back to FIGS. 1 through 4, a practitioner in the art will readily see many applications of the claimed invention. The preferred embodiment of the invention is available for use on a plurality of transportation devices including, but not limited to, wheel chairs, floor cleaners, equipment movers, personnel vehicles, material handling systems, and the like. The axle-drive apparatus eliminates the need for additional mechanical assemblies associated with systems requiring two individual motors along with the independent motors. 
     While there has been illustrated and described what is at present to be a preferred embodiment of the claimed invention, it will be appreciated that numerous changes and modifications are likely to occur to those skilled in the art. It is intended in the appended claims to cover all those changes and modifications that fall within the spirit and scope of the claimed invention.