Abstract:
A sander comprised of a high voltage direct current motor for providing rotational torque to the sander is disclosed. In an exemplary embodiment, a motor housing generally encompasses the motor for enclosure of the motor. The motor housing being generally contoured to be received by a human hand and sized to a generally sized human hand. Further, a sanding assembly is operationally coupled to the motor housing for providing an abrasive surface to be used to sand a desired surface. The use of a voltage direct current motor allows the belt sander to be generally the size of a human hand.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of woodworking and particularly to a belt sander. 
   BACKGROUND OF THE INVENTION 
   Woodworkers often have to smooth the surface of a workpiece prior to the completion of a woodworking project. For example, most workpieces require at least a minimal amount of sanding in order to remove any excess glue or rough edges prior to completion of the project. Currently, a number of different types of sanders are available to improve the surface quality and appearance of a workpiece. Such sanders range from a piece of sandpaper wrapped around a scrap of wood to motorized sanders including orbital sanders and quarter pad finishing sanders. 
   The selection of a specific type of sander depends upon the condition and type of workpiece. For example, for finer finishing work a quarter pad finishing sander or an orbital sander may be utilized. Both a quarter pad finishing sander and orbital sander utilize a sandpaper pad connected onto a plate on the bottom of the sander. Further, the height and shape of the housing of a quarter pad finishing sander is substantially similar to that of an orbital sander (e.g. relatively tall and conical in shape). The pattern of movement is different, however, between such sanders whereby the quarter pad finishing sander moves the pad back and forth while an orbital sander moves such pad in a small circular motion. Due to the type of action implemented by these sanders, however, if a woodworker desires to remove material quickly a more aggressive sander might be employed. 
   Although the conventional motorized sanders, e.g. orbital sanders and quarter pad finishing sanders, have increased the ease in which sanding may be performed, such sanders are disadvantageous in certain circumstances. First, current orbital sanders and quarter pad sanders are often relatively tall which results in a greater distance between the operator&#39;s hand and the work piece and the chance that the sander may drift. Further, the shape of such sanders is often conical which is difficult to grasp and thus, difficult for the user to control. For example, a user is often required to grip the sander in such a manner that one&#39;s hand is perpendicular to the sanding assembly. In addition, such sanders are designed mostly for finer finishing work in which the sander is designed to remove material more slowly when compared to other configurations of sanders. The currently available more aggressive type of sanders are often undesirable for they are typically large, bulky, and cumbersome to operate. 
   Therefore, it would be desirable to design a sander with a contour and size which allowed the user to exert better control over such sander while in use. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to a belt sander. In exemplary embodiments, the belt sander includes a high voltage direct current motor for providing rotational torque to the sander is disclosed. In an exemplary embodiment, a motor housing generally encompasses the motor for enclosure of the motor and motor control components. The motor housing is generally contoured to be received by a human hand and sized to a generally sized human hand. Further, a sanding assembly is operationally coupled to the motor housing for providing an abrasive surface to be used to sand a desired surface. The sanding assembly includes a plurality of rollers, the plurality of rollers including a front roller and a rear roller, the front roller being of a smaller diameter than the rear roller. The motor housing generally contoured to be received by the human hand and sized to the generally sized human hand allows a user to control the belt sander with one hand. 
   In specific aspects of the present invention, the motor is oriented in line with the direction of travel of the sanding assembly. Further, a power switch may be disposed within the front of the housing to control the transmission of electricity to the motor. In addition, a variable speed switch or dial may be disposed within the front of the housing to allow a user to vary the speed of the motor. In additional embodiments, the motor housing is contoured so that a user&#39;s hand and wrist occupy different planes during use of the belt sander. Moreover, the belt sander may include a gearing system for transmitting torque to the sanding assembly. In an exemplary embodiment, such gearing system is enclosed by a gear housing to prevent dust and debris from entering the gearing system and for dampening noise. In still further embodiments, the motor housing contouring defines an indentation for a user&#39;s thumb. 
   It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which: 
       FIG. 1  is an isometric illustration of a belt sander in accordance with the present invention; 
       FIG. 2  is an alternate side view of the belt sander shown in  FIG. 1 ; 
       FIG. 3  is a partial side view of the belt sander shown in  FIG. 1 , wherein a sanding assembly including a drive belt pulley and a pitch belt is illustrated; 
       FIG. 4  is an isometric view of the belt sander shown in  FIG. 1 , wherein the motor housing is removed revealing a gearing system, including a gear housing, for transmitting torque to the drive belt pulley; 
       FIG. 5  is a cross-sectional view of the belt sander shown in  FIG. 1 , wherein a sanding assembly including a sanding belt wrapped around a front roller and a rear roller is illustrated; and 
       FIG. 6  is an isometric view of the belt sander shown in  FIG. 1 , wherein the placement of a user&#39;s hand is illustrated. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. It is to be appreciated that corresponding reference numbers refer to generally corresponding structures. 
   Referring in general to  FIGS. 1–6 , a belt sander in accordance with the present invention is provided. The instant sander body is contoured to allow a woodworker to easily grip the sander and apply the sander to a workpiece. In an exemplary embodiment, the motor housing is substantially contoured to be received by a human hand. For example, the entire motor housing is configured to conform to a user&#39;s hand. In a further embodiment, the front roller of the sanding assembly is of a smaller diameter than the diameter of the rear roller adjacent to a power cord. Thus, the resulting configuration of the present belt sander allows a woodworker to exert better control over the leading edge of the sander by providing an ergonomically configured motor housing. The present invention therefore permits efficient control over the belt sander thereby overcoming the drawbacks experienced with the prior art. In addition, the instant belt sander permits material removal in limited work environments whereby the use of a high voltage direct current motor provides rotational torque to the sanding assembly in manner allowing the sander to be compact in size. 
   Referring specifically to  FIG. 1 , a belt sander  100  in accordance with an exemplary embodiment of the present invention is provided. The belt sander  100  includes a motor  102  (as shown in  FIG. 4 ) for providing rotational torque to a sanding assembly  104  included within the belt sander  100 . In an exemplary embodiment, a high voltage direct current (HVDC) motor is included in lieu of a traditional induction or synchronous motors. Use of a HVDC motor offers improved efficiency, multi-speed control and less/lower frequency noise when compared to traditional induction or synchronous motors. Additionally, in an exemplary embodiment, the motor  102  axis is oriented in-line with the direction of travel of a sanding assembly  104 . The in-line configuration of the motor  102  allows the weight of the motor  102  to be uniformly distributed over substantially the entire sanding interface. The in-line configuration allows the assembly to be lighter, when compared to transverse belt sanders, which is advantageous for decreasing user fatigue especially if a user is performing sanding overhead. 
   As illustrated by  FIG. 1 , in an exemplary embodiment of the present invention, a motor housing encloses the motor  102  and motor control components. In the exemplary embodiment, the housing motor  106  is contoured to provide a griping surface for a user. For example, the motor housing  106  is configured to the shape of a user&#39;s palm so that the user&#39;s palm is place directly over the motor housing  102  so that in use the user&#39;s hand and wrist are parallel with the direction of travel of the sanding assembly. Such configuration is advantageous over conventional belt sanders for it allows the user to maintain sufficient control of the sander. 
   In exemplary embodiments, the housing is formed of materials which include the desired rigidity, machinability and impact resistance such as polyvinyl chloride (PVC), acrylonitrate-butadiene-styrene (ABS), ultra high molecular weight polyethylene (UHMW) plastic, and the like. In additional embodiments, soft grip sides  108  and top  109  are included to reduce vibration transferred to the user and allow a user to maintain efficient control over the sander  100  by providing an easier to grip surface. In such embodiments, the soft grip sides  108  may be formed of elastomeric material such as foam, rubber, rubber impregnated with gel, or the like. It is contemplated that gripping pads may be included in addition to or instead of soft grips sides. 
   In further additional embodiments of the present invention, the belt sander  100  includes a power cord  134  and switch  110  to control power transmission to the motor  102  and motor components. In an exemplary embodiment, the power cord  134  is located on the rear of the motor housing  106  to allow operation of the belt sander  100  without interference of the power cord  134 . The rear of the motor housing  106  being defined as the part of the sander  100  which is covered by the a user&#39;s wrist and the lower edge of a user&#39;s palm. In further exemplary embodiments, the power switch  110  is located on the front of the housing  106  relative to the power cord  134 . Such configuration allows a user to grip the belt sander  100  via the side grips  108 , gripping pads or the like while minimizing inadvertent manipulation of the power switch  110  (as illustrated in  FIG. 6 ). However, the power switch  110  is within a finger&#39;s reach allowing a user to reach the switch  110  if desired. 
   In additional embodiments, the belt sander  100  includes a mechanism to allow for speed variation. For example, in one embodiment, the power switch  110  is a multi-positional switch allowing a user to vary motor speed as desired. Use of the HVDC motor, as described above, allows the belt sander to be capable of operating at various speeds. In an exemplary embodiment, the switch  110  is located on the front of the motor housing  106  relative to the power cord  134  allowing a user to alter the speed of the sander without the user having to vary gripping position orientation. In further exemplary embodiments, the belt sander  100  includes a separate switch/dial for speed variation. In such embodiment, the additional switch/dial may also be located on the front of the motor housing  106  relative to the power cord  134 . The present configuration allows motor speed to be varied without the user having to vary gripping position orientation. For example, the switch/dial may be configured so that it may be manipulated by a user&#39;s index finger. Further, the dial may denote pre-defined increments of variations in speed. In addition, the dial may also allow for smaller incremental variations in speed within the pre-defined increments. 
   In an exemplary embodiment, the belt sander includes the sanding assembly  104 . Such assembly  104  is enclosed by a skirt  112  of the motor housing  106 . In exemplary embodiments, the skirt  112  is formed of materials which include the desired rigidity, machinability and impact resistance such as polyvinyl chloride (PVC), acrylonitrate-butadiene-styrene (ABS), ultra high molecular weight polyethylene (UHMW) plastic, and the like. In an advantageous embodiment, the skirt  112  is light weight and contoured to the general size of the motor housing  106 . Further, the skirt  112  protects the components within the sanding assembly  104  from damage as well as prevents dust and debris from entering the assembly  104 . 
   As illustrated in  FIG. 2 , the sanding assembly  104  includes a front roller  114  and a rear roller  116  relative to the power cord  134 . In an exemplary embodiment, the front roller  114  is of a smaller diameter than the rear roller  116  resulting in the rake of the motor housing  106  to be at an incline. Such configuration provides an inclined grip surface allowing a user hand, wrist and elbow to align in various planes. Providing the ability for the user&#39;s hand, wrist, and elbow allow the user to control the sander with one hand while in use whereby the inclined grip surface allows the sander  100  to fit snugly in the palm of the user&#39;s hand providing a user with better control over the leading edge of the belt sander  100  when a user&#39;s arm is angled. For example, the mushroom contour of the belt sander  100  allows a user to grip the sander  100  with one&#39;s thumb resting within a lower channel or recess. In further exemplary embodiments, the front roller  114  is an idle roller. In an alternative embodiment, power is transmitted to the front roller  114  from the rear roller  116  via a transmission system. 
   In additional exemplary embodiments, the sanding assembly  104  includes a pulley system which transmits the torque provided from the motor  102  to the sanding assembly  104 . The pulley system includes a plurality of pulleys and belts. As illustrated in  FIG. 3 , in an exemplary embodiment the plurality of pulleys include a drive belt pulley  118  and a driven pulley  120 . Further, in such embodiment, a pitch belt  122  is present to transfer rotation from the drive belt pulley  118  to the driven pulley  120  which is connected to the rear sanding belt roller  116 . In an advantageous embodiment, the width of the pitch belt  122  is three (3) millimeters. Such size of belt allows rotation to be transferred from the drive belt pulley  118  to the driven pulley  120  effectively while minimizing the footprint of the belt sander  100 . Additionally, the plurality of pulleys and the pitch belt are enclosed by a belt or transmission housing  124  (shown in  FIG. 1 ). Such housing  124  prevents dust and debris from entering and possibly interfering with the function of various components. 
   In even further exemplary embodiments, as illustrated in  FIG. 4 , power is transmitted to the drive belt pulley  118  via a gearing system  126 . In an advantageous embodiment, the gearing system  126  is a crossed helical gearing system or a worm-drive gearing system is utilized to transmit power to the drive belt pulley  118 . The use of a crossed helical gearing system or a worm-drive gearing system is advantageous for such systems reduce vibration/noise generated during operation as well as the stress placed on the gearing system in comparison to alternative gearing systems (e.g. spur gearing systems). In additional embodiments, the gearing system  126  is enclosed by a gear housing  127 . The gear housing  127  provides an additional barrier to dust and debris, dampen noise, and to allow for subassembly. 
   Additionally, as demonstrated in  FIG. 5 , a sanding belt  128  includes abrasive material extending around the front roller  114  and the rear roller  116 . In an exemplary embodiment, the sanding belt  128  is two and a fourth (2¼) inches wide and thirteen (13) inches long. In an alternative embodiment, the sanding belt  128  is two and a half (2½) inches wide and thirteen (13) inches long. Such size provides a maximum sanding surface while maintaining the size of the belt sander  100  to one which may fit snuggly within that of a typical human hand to allow for efficient control. It is contemplated that the type as well as the size of abrasive material included within the sanding belt may vary depending upon the users need such as to allow for less aggressive fine sanding. 
   In additional exemplary embodiments, the sanding assembly  104  includes a belt tensioning adjuster  130  allowing a user to apply or release tension to the sanding belt  128 . For example, the sanding assembly  104  may include an extending platen to extend or shorten the path of travel of the sanding belt or to extend an idle roller forward and back. Further, an additional belt tracking adjuster  132  may also be included to allow for tool free alignment of the sanding belt  132 . In an exemplary embodiment, the belt tracking adjuster  132  is included within the front of the sanding assembly  104 . For example, if the sanding belt  128  starts to track to one side of the sander  100 , a user may adjust the belt tracking by rotating the belt tracking adjuster  132  whereby clockwise movement of the belt tracking adjuster moves the belt to the right when facing the sander  100  while counterclockwise movement moves the belt to the left. 
   In use, the motor provides torque to the sanding assembly  104  via a gearing system  126  (e.g. a cross helical or worm drive gearing system) wherein such system transmits power to the drive belt pulley  118 . In turn, the pitch belt  122  then transfers rotation from the drive belt pulley  118  to the driven pulley  120  and the rear sanding belt roller  116 . The instant configuration thereby allows a user to operate the belt sander  100  vertically, horizontally or at various angles in-between. 
   In additional embodiments, it is contemplated that the belt sander  100  may include mechanisms designed to minimize or eliminate dust generated by fast sanding action. For example, in one embodiment, the belt sander  100  may include an integrated dust collection system which allows dust to be collected within a receptacle during operation. In an additional embodiment, the belt sander  100  may include a dust outlet allowing the belt sander  100  to be directly connected to a conventional shop vacuum hose or a centralized vacuum system. In further exemplary embodiments, a dust collection skirt may be included for managing dust generated during use. In an exemplary embodiment, the dust collection skirt may be located towards the rear of the sander  100  towards the power cord  134  in order to not interfere with the operation of the sander  100  and to direct dust away from the workpiece. 
   It is believed that the present invention and many of its attendant advantages will be understood by the forgoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.