CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority to U.S. patent application Ser. No. 12/176,700, filed Jul. 21, 2008, titled “CONVEYOR DRIVE ROLLER,” now U.S. Pat. No. 7,806,252, which issued on Oct. 5, 2010, and Canadian Application No. 2619247, filed Feb. 5, 2008, titled “CONVEYOR DRIVE ROLLER,” the contents of which are incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The present invention relates generally to conveyor roller systems for conveying or moving objects from one place to another. Conveyor systems generally employ a series of rollers on which a continuous belt or other conveyor medium travels. Some of the rollers in such a system act as drive rollers and are rotated to move the belt. The present invention relates, in particular, to conveyor drive rollers driven by electric motors for use in such conveyor belt systems. 
     BACKGROUND OF THE INVENTION 
     A variety of conveyor roller systems have been designed and utilized. A large variety of known conveyor systems comprise a continuous belt or conveyor medium which travels over a series of conveyor rollers. 
     Early conveyor roller systems utilized at least one conveyor drive roller which was driven by an electric motor positioned outside of, and connected to, the conveyor drive roller typically via a chain or rubber belt, and often with an external gear assembly positioned between the motor and the conveyor roller. The conveyor drive roller thereby translated the rotational movement of the electric motor to linear movement of the conveyor medium. The main disadvantage of these early designs, which are still utilized today, is that they take up a lot of space. However, the exposed moving parts also pose a hazard to workers, especially the external gear assembly and chain from the external gear assembly to the conveyor roller, which output high levels of torque, as compared to the motor on its own. The exposed moving parts also pick up debris which damages the conveyor roller system. 
     In later conveyor roller systems, the electric motor was arranged within the conveyor drive roller to provide a more compact conveyor roller system as taught, for example, in U.S. Pat. No. 1,725,740 to Schulte. 
     An example of an even more advanced conveyor drive roller is disclosed in U.S. Pat. No. 5,088,596 to Agnoff; which teaches a motorized conveyor drive roller mounted in a conveyer frame to support and propel articles from one end of the conveyor path towards the opposite end. The Agnoff conveyer drive roller includes a roller tube rotatably mounted in the conveyor frame and drive means contained inside the roller tube for driving the roller tube. The drive means includes a motor, a gear reducer assembly operatively connected to the motor, and a drive member connected to the outward shaft of the speed reducer for engaging and rotating the roller tube. 
     Conveyor roller systems having conveyor drive rollers which are driven by motor and gear combinations, contained entirely within the conveyor drive roller itself, are of particular utility in many applications. The internal motor and gear system makes for a compact, space saving installation. Furthermore, the linear arrangement of the motor and gearing within the conveyor drive roller means that the transmission of power from the motor to the roller is carried out more directly resulting in higher levels of efficiency than is possible in conventional conveyor roller systems where the motor is located externally to the conveyor drive roller, especially where the axis of rotation of the rotor is at a 90° angle to the axis of rotation of the roller. The internal motor and gear combination also largely eliminates the risk of accident caused by contact with employees. Furthermore, it eliminates contamination of the motor/gear drive from dust and debris in the environment in which it is running, thereby greatly reducing maintenance, and the likelihood of failure, all of which results in less down time for the conveyor system. 
     All of these factors make the use of such conveyor drive rollers particularly useful and desirable. However, they also have disadvantages. 
     One such disadvantage is that while the likelihood of failure of such a conveyor drive roller is decreased, when it does fail servicing is very difficult and expensive, since it requires the shutting down of the conveyor roller system, removal of the entire defective conveyor drive roller (which is quite heavy since it contains the motor and gearing), which is then sent elsewhere for servicing. The conveyor roller system remains shut down until a new or repaired conveyor drive roller is installed in the conveyor system in place of the removed, defective one. Since conveyor drive rollers of this type (i.e. having the motor and gearing within them) are fairly expensive, companies that employ conveyor systems which utilize them typically do not stock spare conveyor drive rollers. This means that the conveyor system remains shutdown until the defective conveyor drive roller is repaired and re-installed. 
     Therefore, there is a need for improvement in the design of conveyor drive rollers. 
     SUMMARY OF THE INVENTION 
     Although mechanical breakdown of conveyor drive motors in which the motor and gear mechanism is entirely contained within the conveyor drive roller itself is far less likely than traditional conveyor drive rollers, they do still break down. It is typically the motor which fails in such units. However, accessing and repairing the motor when it is located inside the conveyor drive roller requires special tooling and significant time, and expense as described above. 
     Therefore, what is desired is a conveyor drive roller which has the advantages of the prior art conveyor drive rollers with the internal motor and gear combination, but which results in less down time when a failure in the motor occurs, by virtue of the motor being outside of the drive roller where it can be more easily accessed, repaired, and/or replaced. 
     Accordingly, the present invention provides a conveyor drive roller in which the gear assembly is contained inside a sealed conveyor drive roller and protected from the environment, while the electric motor is located outside of the conveyor drive roller and connected to the internal gear assembly. This facilitates preventative servicing and maintenance, and simplifies replacement and repair of the motor if it fails. 
     Furthermore, workers near the conveyor drive roller are protected from accidentally coming into contact with the moving parts of the gear assembly (since it is located within the conveyor drive roller), which may cause physical damage or catch any loose clothing into the system, as may otherwise occur in a conventional conveyor drive roller, in which the gear reducer, motor, couplings, and belts or chains are exposed outside of the roller. 
     Another advantage is that with the internal gear assembly and external motor, the conveyor drive roller of the conveyor drive roller of the present invention is more compact than the conventional drive roller, in which the gear reducer, motor, couplings, and belts or chains are outside of the roller. 
     Yet another advantage of the conveyor drive roller of the present invention is that by locating the motor outside of the conveyor drive roller the motor does not need to be sold with the conveyor drive roller. This allows the user to purchase an economical spare motor, from any supplier, to be kept in stock in case it becomes needed to replace a defective motor. The replacement of the motor in this invention is much faster and easier than replacing the motor in a drive roller where the motor is located within the roller. This arrangement also allows the user to select from a range of standard motors when building the conveyor system, or to upgrade or change an installed conveyor system to perform in a different application or environment. 
     Yet another advantage is that by coupling the external motor directly to the internal gear assembly and aligning the axis of rotation of the rotor parallel with the axis of rotation of the conveyor drive roller the transfer of power from motor to roller is very efficient. Such an arrangement results in energy cost savings relative to conventional conveyor drive rollers, in which the axis of rotation of the rotor is typically at a 90° angle to the axis of rotation of the roller, for space conservation. 
     Therefore, in accordance with one aspect of the present invention there is provided a conveyor drive roller comprising: 
     a hollow drum defining a rotatable supporting surface having a cylindrical shape and an internal surface, said hollow drum being rotatably connected to a first and a second support structure; 
     an internal gear assembly disposed inside said hollow drum and operably connected to said internal surface of said hollow drum; 
     said second support structure being adapted to permit a rotor of a motor located outside of said hollow drum to releasably couple to said internal gear assembly through said second support structure; 
     wherein when said rotor is coupled to said internal gear assembly, through said second support structure, rotation of said rotor is transmitted by said internal gear assembly to said hollow drum to cause rotation of said hollow drum about said first and second support structures. 
     In accordance with another aspect of the present invention there is provided a conveyor drive roller comprising: 
     a hollow drum defining a rotatable supporting surface having a cylindrical shape, said hollow drum being rotatably connected to a first and a second support structure; 
     an internal gear assembly disposed inside said hollow drum and operably engaging said hollow drum; 
     a rotatable element rotatably carried by said second support structure, said rotatable element having two ends, one of said ends operably engaging said internal gear assembly, and the other of said ends being adapted to couple to a rotor of a motor; 
     wherein when said rotor is coupled to said other end of said rotatable element, rotation of said rotor is transmitted by said rotatable element and said internal gear assembly to said hollow drum to cause rotation of said hollow drum about said first and second support structures. 
     In accordance with yet another aspect of the present invention there is provided a conveyor drive roller for supporting and driving a conveyor medium, said conveyor drive roller comprising: 
     a hollow drum defining a rotatable supporting surface having a cylindrical shape, said hollow drum being rotatably connected to a first and a second support structure, said second support structure having a channel therethrough, and an exterior end adapted to mount a motor with a rotor; 
     an internal gear assembly disposed inside the hollow drum; 
     said internal gear assembly being operably connected to said hollow drum; 
     said internal gear assembly also being adapted to operably couple to said rotor; 
     wherein when said motor is mounted to said exterior end and said internal gear assembly is operably coupled to said rotor, through said hollow channel, rotation of said rotor is transmitted by said internal gear assembly to said hollow drum to cause rotation of said hollow drum about said first and second support structures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the preferred embodiments of the present invention with reference, by way of example only, to the following drawings in which: 
         FIG. 1  is a full cross-sectional view of a conveyor drive roller according to an embodiment of the present invention; 
         FIG. 2  is partial view of a cross-section of one end of the conveyor drive roller of  FIG. 1 ; 
         FIG. 3  is a partial view of a cross-section of the other end of the conveyor drive roller of  FIG. 1 , with parts omitted for clarity; 
         FIG. 4  is a partial view of a cross-section of the other end of the conveyor drive roller of  FIG. 3  with omitted parts present and a motor mounted thereto; 
         FIG. 5  is a partial view of a cross-section of a portion of the conveyor drive roller of  FIG. 1  showing the internal gear assembly; and 
         FIG. 6  is a full cross-sectional view of a conveyor drive roller according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is described in more detail with reference to exemplary embodiments thereof as shown in the appended drawings. While the present invention is described below including preferred embodiments, it should be understood that the present invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments which are within the scope of the present invention as disclosed and claimed herein. In the figures, like elements are given like reference numbers. For the purposes of clarity, not every component is labelled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. 
     A conveyor drive roller  10  according to the present invention is disclosed in FIG.  1 . The conveyor drive roller  10  consists of a cylindrical drum  12 , having ends  14  and  16 . Stationary shafts  18  and  20  extend through respective ends  14 ,  16 . The stationary shafts  18  and  20  can be mounted on any suitable support or frame work (not shown) and secured on for example blocks or clamps (not shown), all of which is known and requires no detailed description. 
     The conveyor media (not shown) typically a belt or flexible strip of any suitable material, or a matrix of chain links, or the like runs around the outer surface  22  of the drum  12  and is driven by drum  12 , which rotates about shafts  18  and  20 . Such conveyor media may also run around other conveyor drive rollers (not shown), and may run over intermediate support rollers (not shown). Furthermore the outer surface  22  can include any variety of means to increase the co-efficient of friction between the outer surface  22  and the conveyor medium such as for example by knurling or machining a spiral at each end toward the center or by covering the outer surface  22  with rubber or the like. 
     As shown in  FIG. 2  in an enlarged view of end  14 , an annular end flange  24 , is press fit into the drive drum  12 . The end flange  24  has a hole in the middle, which defines a lip  26  facing outside of the drive drum  12 . A bearing cassette  28  is fit within the hole in the end flange  24 . The cassette has a collar  32  for securement to the lip  26  of the end flange  24  by fasteners  30 , such as socket head caps as shown. Two spaced apart bearings  34  are positioned within the cassette  28  about the shaft  18 . The exterior portion  17  of shaft  18  is preferably mountable on, and securable to, a suitable support or frame work (not shown). For example, the exterior portion  17  of shaft  18  may have a generally cylindrical profile with two flat sections at opposite sides, for locking in a U-shaped member, or clamp on the frame. Furthermore, although two bearings  34  are preferred in order to reduce the amount of play on the shaft  18 , as is well known in the art, it is contemplated that one bearing positioned in the cassette  28  will also work. It is also contemplated that the end flange  24  and cassette  28  may be provided as a unitary construction. What is important is that drum  12  is rotatably connected to shaft  18  at end  14 . 
       FIG. 3  is an enlarged view of end  16 , with parts omitted to more clearly show how drum  12  is rotatably connected to shaft  20 . As shown, a securing ring  36  is press fit into the drive drum  12 . End flange  38  is secured to the securing ring  36  by fasteners  40 , such as socket head caps as shown, with a gasket  37  positioned between the securing ring  36  and the end flange  38 . The end flange  38  is sized and shaped with a hole to accommodate bearing  42 , bearing race and oil seal  46  about shaft  20 . Preferably, shaft  20  has a hollow interior and comprises three components, namely a C-flange motor mount  48 , an extender  50 , and an internal gear assembly mount  52 . C-flange motor mount  48  is preferably sized and shaped for mounting a motor  54  according to the National Electrical Manufacturers Association (NEMA) standards. The three components are secured together with fasteners  53  in a known manner. However, it will be appreciated that the shaft  20  may comprise more or fewer components. What is important is that drum  12  is rotatably connected to shaft  20  at end  16 , and be capable of operably mounting an external motor  54 . Shaft  20  is preferably mountable on, and securable to, a suitable support or frame work (not shown) at extender  50 . For example, the exterior of extender  50  may have a generally cylindrical profile with two flat sections at opposite sides, for locking in a U-shaped member, or clamp on the frame. 
     As can now be understood shafts  18  and  20  form a support structure about which drum  12  can rotate, when mounted on a suitable frame (not shown). 
       FIG. 4  is an enlarged view of end  16 , with parts omitted to more clearly show how motor  54  is coupled to the internal gear assembly (omitted from this view). As shown, motor  54  is a conventional electric motor, and is therefore not described in any more detail. Preferably the motor is sized and shaped in accordance with the NEMA standards, which will fit an appropriately sized and shaped C-flange motor mount  48  of shaft  20 . The motor  54  is mounted to the C-flange motor mount  48  by fasteners  56 , such as socket head caps as shown. The rotor  58  of the mounted motor  54  extends through bearings into the hollow of shaft  20 . One half of a Lovejoy® coupling (i.e. LO 95)  62  is secured to the operative end of the rotor  58 . The other half of the Lovejoy® coupling  64  is secured (i.e. by press fitting) to one end of a rotational element  66 . The other end of the rotational element  66  has a pinion  68 . A spider insert  70  is positioned between the two halves of the Lovejoy® coupling. As is known in the art the spider  70  has vibration dampening properties and misalignment correction capabilities, etc. While the preferred mode of coupling the motor  54  to the internal gear assembly is described as using a Lovejoy® coupling, it will be understood that many other types of coupling are possible and will be known to persons skilled in the art, such as a tongue and groove couplings. What is important is that the mode of coupling will permit the motor  54  to easily decouple from the rotational element  60 , such as for example by simply sliding the motor  54  away from the C-flange motor mount  48 . This permits easy access to the motor  54  for maintenance, repair and replacement, without necessitating the removal of the entire conveyor drive roller  10  from the conveyor frame (not shown). Thus, repair or replacement of a faulty motor  54  will typically result in only a brief down time of the conveyor. Furthermore, with the internal gear assembly being provided inside the drum  12 , the conveyor drive roller  10  according to the present invention takes up less space as compared to a conventional conveyor drive roller (not shown) in which the gear reducer, motor, and couplings and belts or chains are all located outside of the conventional conveyor drive roller. Moreover, providing the internal gear assembly inside the drum  12  removes the possibility of debris (which can cause damage to the conventional conveyor drive roller), and especially worker&#39;s clothing being caught (which is a hazard), both of which possibilities are issues with conventional conveyor drive rollers in which the moving parts of the gear reducer, motor, couplings and belts or chains being exposed. The torque from the gear reducer and belts or chains is much higher, and more dangerous to nearby workers, than the torque from the motor itself. 
     With continued reference to  FIG. 4 , the rotational element  66  is shown preferably of unitary construction, and being sized and shaped to pass through the hollow of shaft  20  to extend past the gear assembly mount  52  inside the drum  12 . Also shown are a bearing  72  and oil seal  74 , between the gear assembly mount  52  and the mid portion of the rotational element  66 . What is important is that the rotational element  66  be capable of transferring the torque from the rotor  58  of the motor  54  to the internal gear assembly (not shown in this view) through the hollow of shaft  20 . 
       FIG. 5  is an enlarged view of a portion of the conveyor drive roller  10  containing the internal gear assembly according to a preferred embodiment of the present invention. As shown, a gear housing  76  is secured to the gear assembly mount  52  with fasteners  78  such as the one socket head cap which can be seen in this view. The gear housing  76  is sized and shaped to hold a bearing  80  about the rotational element  66  adjacent the pinion  68 , and a drive gear  82  in engaging relation with the pinion  68 . The drive gear  82  preferably comprises an output gear  84  with a shaft  86  extending therefrom, a sleeve  88  press fit about a portion of the shaft  86 , and a gear  90  press fit about a portion of the sleeve  88 . The drive gear  82  is rotatable in the gear housing  76  by bearing  92  and needle bearing  94 . A spacer  96  is shown about the sleeve  94  between the gear  90  and the bearing  92  to prevent the gear  90  from rubbing against the gear housing  76 . As can now be understood, the teeth of the pinion  68  mesh with the teeth of the gear  90  so that rotation of the rotational element  66  causes rotation of the drive gear  82  within the gear housing  76 . 
     The teeth of the output gear  84  mesh with interior ring gear  98  on plate  100 , which is secured to mid flange  102 , which in turn is sealingly secured to a mounting ring  106  which is press fit inside the drum  12 . As will be appreciated, the securement of the plate  100  to mid flange  102 , and the mid flange  102  to the mounting ring  106  may be by fasteners  104 . It is also contemplated that mounting ring  106 , plate  100 , and mid flange  102  may be provided as a unitary construction, or a two, or more piece construction. What is important is that rotational movement of output gear  84  is translated into a rotational movement of drum  12 . Furthermore, it is preferable to extend a stabilizing shaft  108  from the gear housing  76 , along the axis of rotation of the drum  12  to a bearing  110  held in mid flange  102  to help prevent the gear assembly from wobbling inside the drum  12  during use. 
     In a preferred embodiment of the present invention the internal gear assembly is configured to reduce the rate of rotational movement of the drum  12  relative to the rate of rotational movement of the rotor  58  by the motor  54 . However, it will be appreciated that the internal gear assembly can be configured to also increase the rotational movement of the drum  12  relative to the rotational movement of the rotor  58  of motor  54 . The use of gears and gear ratios to be used, which will be understood by those skilled in the art; and therefore, requires no detailed description. 
     A compartment  112  containing the gear assembly is formed between the mid flange  102  and end flange  38 . Preferably, the compartment  112  is partly filled with gear oil, ensuring proper lubrication and cooling during operation of the conveyor drive roller  10 . 
     In use, conveyor drive roller  10  is mounted to a frame (not shown) by shafts  18  and  20 , in a manner which prevents shafts  18 ,  20  from rotating. When energised by operation of a suitable start switch (not shown) motor  54 , spins rotor  58 , which is coupled to rotational element  66  by the Lovejoy® coupling  60 ,  62 ,  64 . Rotational element  66  has at its other end a pinion  68  which meshes with gear  90 , at one end of drive gear  82 , causing the output gear  84 , at the other end of drive gear  82  to rotate in gear housing  76 . Output gear  84  meshes with ring gear  98  which causes the drum  12  to rotate about stationary shafts  18  and  20 , since output gear  84  is linked to the inside of the drum  12  by virtue of the securement to mid plate  102  and ultimately to the inside of the drum  12  via mounting ring  106 . Rotation of drum  12  in turn causes movement of the conveyor media (not shown) carried on drum  12 , which will move any product on the conveyor along its desired path. 
     The inline mounting of the motor  54  to the conveyor drive roller  10  according to the present invention, wherein the motor  54  is directly coupled to the internal gear assembly, and the rotor&#39;s  58  axis of rotation is parallel with the conveyor drive roller&#39;s  10  axis of rotation results in significant energy savings compared to conventional conveyor drive rollers with external gear reducers, motors, couplings, and belts or chains, because the transfer of power is much more efficient. 
     While reference has been made to various preferred embodiments of the invention other variations are comprehended by the broad scope of the appended claims. Some of these have been discussed in detail in this specification and others will be apparent to those skilled in the art. 
     For example, according to another embodiment of the present invention, it is contemplated that to take up less space, the motor  54  may be mounted underneath the drum  12 . Accordingly, the conveyor drive roller  10  may be provided with a shaft  20  without the C-flange motor mount  48 , and in place of the Lovejoy® coupler  64 , the end of the rotational element  66  may be provided with a pulley  114 . Thus, as shown by way of example in  FIG. 6 , the motor  54  is coupled to the rotational element  66  by a power transmission belt  116 . 
     All such variations and alterations are comprehended by this specification are intended to be covered, without limitation.
There is disclosed a conveyor drive roller of the type which may be used for example for supporting and driving a conveyor medium. The conveyor drive roller has a hollow drum which defines a cylindrically shaped rotatable supporting surface, and an internal surface. The hollow drum is rotatably connected to a first and a second support structure. An internal gear assembly is disposed inside of the hollow drum and operably connected to the internal surface of the hollow drum. The second support structure is adapted to permit a rotor of a motor located outside of the hollow drum to releasably couple to the internal gear assembly through the second support structure, so that when the rotor is coupled to the internal gear assembly, through the second support structure, rotation of the rotor is transmitted by the internal gear assembly to the hollow drum to cause rotation of the hollow drum about the first and second support structures.