Patent Publication Number: US-7220174-B2

Title: Drywall sander

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 60/614,189, entitled “Drywall Sander,” filed Sep. 29, 2004 and U.S. Provisional Patent Application Ser. No. 60/643,058, entitled “Drywall Sander with Interchangeable Heads,” filed Jan. 11, 2005 both of which are herein incorporated by reference in their entireties. 

   FIELD OF INVENTION 
   The present invention generally relates to the field of power tools, and more particularly to a device for sanding drywall. 
   BACKGROUND OF THE INVENTION 
   In order for the joints between drywall panels to disappear so that the walls and ceilings are smooth, a compound known as joint compound is employed. First, joint compound is applied over the joints in excess and allowed to dry. Second, the excess compound is removed by a sander. It is the removal of the excess joint compound that is often difficult as well as tedious. 
   Traditionally, a non-motorized, hand or pole sander was most commonly utilized to remove joint compound. However, use of a non-motorized sander often led to user fatigue and was very time consuming. Thus, the non-motorized, hand or pole sander has generally been replaced with a motorized drywall sander including a rotational sanding pad head. 
   Although currently available motorized drywall sanders have increased the speed in which the compound may be removed, such sanders are limited. First, the amount of time required to complete a sanding job may be actually increased when using such sanders when compared to a non-motorized sander. For example, while the speed of compound removal is increased with use of a motorized sander the overall time associated with the job may not be shortened because of the large amount of dust generated by the motorized sander, making clean-up more difficult and thus, time consuming. 
   Currently, two primary solutions have been employed to reduce the clean-up time associated with the sanding of drywall with a motorized sander. One solution confines the generated dust by the placement of plastic sheets over all openings leading to dwelling areas in which drywall work is not occurring. In addition to separating the work area from the other dwelling areas, a box fan may be placed in an open window in order to blow the dust outdoors. Such solution confines the majority of dust to the room in which the sanding is being performed, however, the user will still have significant clean-up in such room. In the alternative, a second solution which reduces the total clean-up significantly is the attachment of a dust collection system to the motorized sander whereby a vacuum draws the sanded drywall dust into a dust collecting vessel as the drywall compound is removed. 
   Although the utilization of a dust collection system with a motorized sander has greatly reduced the amount of dust and therefore, clean-up required, users of such sanders are currently required to purchase multiple sizes and types of these sanders to accomplish a single job. For instance, a user may need a pole sander to reach the ceiling, but wish to use a hand sander for jobs close to the ground. Further, to accomplish inside corner sanding a sander with a triangular head instead of a circular head may be desired. As a result, the user is forced to purchase multiple sanders or to use a sander which may not result in a completely smooth area because access is limited. 
   Therefore, it would be desirable to provide a drywall sander system capable of adjustment in length and collecting dust and debris, which system includes differently shaped interchangeable sanding heads to allow for multiple types of areas to be sanded with use of a single tool in an efficient manner. 
   SUMMARY OF THE INVENTION 
   In a first aspect of the present invention, a sander including a power unit is disclosed. The power unit includes a motor for supplying rotational torque to the sander. A sanding assembly is operationally coupled to the power unit. A telescopic support arm assembly is coupled to the sanding assembly and the power unit for supporting the sanding assembly. The telescopic support arm assembly includes a first support arm with a first and a second end and a second support arm with a first and second end. The first end of the first support arm may be coupled to the power unit while the second end of the second support arm may be coupled to the sanding assembly. Moreover, a collapsible drive shaft is substantially enclosed by the telescopic support arm assembly. The telescopic support arm assembly and the collapsible drive shaft allow the length of the telescopic assembly to be adjusted. 
   In a further aspect of the present invention, a sander including a power unit is provided. The power unit includes a motor for supplying rotational torque to the sander. A plurality of sanding heads each capable of being coupled to the power unit are included. The sander includes a sanding head connection assembly for coupling one of the plurality of sanding heads to the power unit. The sanding head connection assembly includes a planetary gear reduction system for imparting more than one type of motion to the sander. The ability of the planetary gear reduction system to impart more than one type of motion to the sander allows such sander to sand multiple types of areas. 
   In an additional aspect of the present invention, a sander including a power unit is disclosed. The power unit includes a motor for supplying rotational torque to the sander. The sander includes a plurality of sanding heads each capable of being coupled to the power unit. A telescopic support arm assembly is coupled to one of the plurality of sanding heads and the power unit for supporting the sanding head. The telescopic support arm assembly may include a first support arm and a second support arm in which the first and second support arms substantially surround a collapsible drive shaft. Moreover, a sanding head connection assembly is included for coupling one of the plurality of sanding heads to the power unit. The sanding head connection assembly includes a planetary gear reduction system for imparting more than one type of motion to the sander. The sanding head connection assembly also includes a sanding head connection adapter for coupling the sanding head connection assembly to one of the plurality of sanding heads. The sanding head connection adapter allows the sanding head to pivot rotationally in relation to the sanding head connection assembly. 
   It is to be understood that both the foregoing 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 view of a powered drywall sander in accordance with an exemplary embodiment of the present invention, wherein the sander includes a telescopic shaft which allows the length of the sander to be adjusted; 
       FIG. 2  is an isometric view of the powered drywall sander in accordance with  FIG. 1 , wherein the telescopic shaft is in an extended position; 
       FIG. 3  is a cross-sectional view of a powered drywall sander in accordance with  FIG. 1 , wherein the powered drywall sander includes a collapsible drive shaft; 
       FIG. 4  is a partial isometric bottom view of a sanding head connection assembly in accordance with an exemplary embodiment of the present invention, wherein the sanding head connection assembly includes a sanding head connection adapter; 
       FIG. 5A  is an isometric view of a planetary gear reduction system in accordance with an exemplary embodiment of the present invention; 
       FIG. 5B  is an exploded view of the planetary gear reduction system illustrated in  FIG. 5A , wherein the planetary gear reduction system includes a shaft with a sun gear and a plurality of planets contained within a ring gear; 
       FIG. 6A  is an isometric view of a rotational sanding pad head in accordance with an exemplary embodiment of the present invention, wherein the head includes a connector with teeth for connecting the head to a sanding head connection assembly; 
       FIG. 6B  is an isometric view of a orbital sanding pad head in accordance with an exemplary embodiment of the present invention, wherein the head includes a connector with teeth for connecting the head to a sanding head connection assembly; 
       FIG. 7  is a partial isometric view of a powered drywall sander in accordance with an exemplary embodiment of the present invention, wherein a rotational head is connected to the sanding head connection assembly; 
       FIG. 8  is a partial isometric view of a powered drywall sander in accordance with an exemplary embodiment of the present invention, wherein an orbital head is connected to the sanding head connection assembly; 
       FIG. 9  is a cross-sectional side view of a sanding head connection assembly in accordance with an exemplary embodiment of the present invention, wherein the positioning of the components of the sanding head connection assembly without a sanding head attached is illustrated; 
       FIG. 10  is a cross-sectional side view of a sanding head connection assembly in accordance with an exemplary embodiment of the present invention, wherein a sanding head is engaged with the assembly; and 
       FIG. 11  is a cross-sectional front view of the sanding head connection assembly as illustrated in  FIG. 10 . 
   

   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. 
   Referring in general to  FIGS. 1 through 11 , a drywall sander including a telescopic support arm assembly and the capability of receiving variously shaped interchangeable sanding heads and providing different motions is provided. Conventional drywall sanders include a rotational pad head capable of rotating at a single speed (e.g. two thousand revolutions per minute, 2000 rpm). Although such sanding head works well for most areas of a wall, access into corners or edges is often limited. For example, a user might not be able to access the corners or edges of a wall easily, causing such surface to be uneven when compared to the surrounding area. In addition, a user may need to sand a portion of the ceiling as well as an area relatively close to the ground surface. The present invention provides a sander which includes a planetary gear reduction system which allows the sanding assembly to impart different motions (e.g., rotational or orbital). Further, the disclosed sander includes a telescopic support arm assembly, allowing a user to adjust the length of the shaft so that the sander may be used as both a hand sander and a pole sander. 
   Referring specifically to  FIGS. 1 through 3 , a drywall sander  100  in accordance with an exemplary embodiment of the present invention is provided in which the sander  100  includes a housing  102  for substantially enclosing a drywall sander power unit. In the present embodiment, the drywall sander power unit includes a motor  104  for supplying rotational torque to the drywall sander  100  and a drive shaft for transferring the rotational torque of the motor  104  to a sanding assembly  108 . For example, the sanding assembly  108  may be capable of coupling to varying shaped heads, each capable of being operationally coupled to the power unit for removing joint compound. In an exemplary embodiment, a sanding head connection assembly  110  is employed to couple a sanding head to the power unit. It is contemplated that more than one drive shaft may be employed to transfer the rotational torque generated by the motor  104  to a sanding head. For example, a first drive shaft  106  formed of metal or the like may be operationally coupled to the motor  104 . In turn, a second drive shaft  114  which is capable of collapsing may be mechanically coupled to the first drive shaft  106 . The second drive shaft  114  may be formed of a lightweight material to minimize the weight of the drywall sander and may extend the length of a telescopic support arm assembly  112 . In addition, a third drive shaft may be coupled to the second drive shaft  114  and the sanding head connection assembly  110 . As illustrated in  FIGS. 1 and 2 , the shaft which connects the second drive shaft to the sanding head connection assembly  110  may be flexible or irregular in shape. 
   In the present embodiment, the telescopic support arm assembly  112  is operationally coupled to the sanding assembly  108  and the power unit for supporting the sanding assembly  108  and substantially enclosing the second or collapsible drive shaft  114  extending to the sanding assembly  108 . In such embodiment, the telescopic support arm assembly  112  includes a first support arm  116  with a first and a second end  118 ,  120  and a second support arm  122  with a first and second end  124 ,  126 , the first end  118  of the first support arm  116  is operationally coupled to the power unit and the second end  126  of the second support arm  122  is operationally coupled to the sanding assembly  108 . As such, the telescopic support arm assembly  112  with the collapsible drive shaft  114  allows the length of the telescopic assembly to be adjusted according to the worksurface which is to be sanded. 
   In the exemplary embodiment, as illustrated in  FIG. 3 , the collapsible drive shaft  114  is held within the telescopic support arm assembly  112  by a collapsible joint  128 . For example, the collapsible joint  128  is a threaded locking collar. It is contemplated that additional mechanisms may be used in addition to the collapsible joint  128  without departing from the scope and spirit of the present invention. In use, a user may extend ( FIG. 2 ) or retract ( FIG. 1 ) the telescopic support arm assembly  112  by loosening the collapsible joint  128 , extending or retracting the first  116  and second  122  support arms including the collapsible drive shaft  114  to a desired position, and then, locking the drive shaft  114  into place by tightening the collapsible joint  128 . For instance, a user may extend the telescopic support arm assembly  112  completely in order to sand a ceiling or completely retract such shaft assembly  112  for use in a small or enclosed area. Therefore, the present invention is advantageous in that it provides the user with both a hand sander and pole sander in one device. Further, the ability of the sander to collapse allows the sander to be stored more easily whereby less space is required when compared to traditional non-adjustable pole sanders. Moreover, shipping costs are also reduced because the retractable sander may be shipped in a smaller box. 
   In an advantageous embodiment, the telescopic support arm assembly  112  is formed of carbon fiber tubing. Use of carbon fiber tubing allows the sander  100  to be lightweight and thus, possibly decrease user fatigue. However, those of ordinary skill in the art will appreciate that the telescopic assembly  112  may be formed by use of numerous types of materials including plastic, fiberglass, metal, metal alloy, and the like without departing from the scope and spirit of the present invention. 
   In accordance with an exemplary embodiment of the powered drywall sander  100 , a user may control the power supplied by the motor  104  to the sanding assembly  108  via use of a power switch  130 . Moreover, in additional embodiments, the powered drywall sander may be equipped with a speed dial (not shown) allowing the speed of the sanding head to be controlled. 
   It is to be understood by those of ordinary skill in art that any standard universal motor may be employed to power the present drywall sander. In an advantageous embodiment, the motor  104  is located in the lower portion of the drywall sander  100  in order to minimize user fatigue. Further, a handle  132  may be defined within the power unit housing  102  for providing a user grip surface. 
   In additional exemplary embodiments, the sander  100  includes a built in dust collection system to contain drywall dust as sanding is performed to minimize the amount of clean-up. In the present embodiment, a built in dust collection vacuum hose  134  travels from a sanding head down the telescopic support arm assembly  112 . Dust and debris may ultimately be deposited into a dust bag, canister or receptacle. In an advantageous embodiment, the handle  132  defined within the power unit housing  102  includes a dust collection tube which allows dust to pass from the telescopic support arm assembly  112  to the desired dust collecting receptacle. In an alternative embodiment, an adapter  135  may be employed to allow the sander  100  to be connected to various types of wet/dry shop vacuums and vacuum cleaners to allow dust to be contained, thereby minimizing clean-up. 
   Referring to  FIGS. 1 and 4  through  11 , the capability of the drywall sander  100  to accommodate varying sized sanding heads and impart more than one type of motion to the sanding system is provided. In an exemplary embodiment, as illustrated in  FIG. 1 , the drywall sander  100  sanding system  108  includes the sanding head connection assembly  110  for connecting a sanding head to the collapsible drive shaft  114  defined within the telescopic support arm assembly  112 , allowing more than one type of motion to be provided by the sander  100 . 
   Referring to  FIG. 4 , an exemplary sanding head connection assembly  110  is provided in which such assembly  110  includes a sanding head connection adapter  136  for allowing a sanding head to pivot rotationally in relation to the sanding head connection assembly  110 . In an exemplary embodiment, a plurality of teeth  142  are defined within the sanding head connection adapter  136 . Such teeth  142  may align with teeth  144  on a sanding head connector  146  allowing the head to be placed in any rotational position relative to the sanding head connection adapter. For example, a circular or rotational sanding pad head  138  in accordance with an exemplary embodiment of the present invention is illustrated in  FIG. 6A  in which the head  138  includes the connector  146  with teeth  144  for connecting the head  138  to a sanding head connection assembly  110 . Alternatively,  FIG. 6B  illustrates an exemplary rectangular shaped or orbital sanding pad head  140  including a connector  146  with teeth  144 . In a preferred embodiment, the outer diameter of the connector on the rotational head is approximately the same size and shape as the outer diameter of the orbital head connector. The presence of the teethed-connector  146  with approximately the same outer diameter size and shape allows the heads to be interchanged with the sanding head connection assembly  110  with little effort. For example, to change from a rotational sanding head to an orbital sanding head, a user simply disconnects the rotational sanding head from the sanding head connection adapter and then, connects the orbital head. Thus, no reconfiguration of the adapter or the sanding head is necessary. In addition, the sanding head connection adapter  136  imparts an additional degree of freedom to the sanding assembly. For example, during use, a sanding head is biased to return to its installed location, but the head is configured to pivot rotationally in relation to the sanding head connection assembly  110  plus or minus approximately forty-five degrees, making it easier for a user to use the sander in the orbital sanding configuration. For instance, it is not necessary for a user to stand directly in-line with the sander when using the sander. 
   In further exemplary embodiments, the sanding head connection adapter  136  included within the sanding head connection assembly  110  may include a compression spring and at least one lever to provide centering load for such adapter  136 . In addition, a lever  150  may be included to assist in securing a sanding head to the sanding head connection assembly  110 . 
   In an additional exemplary embodiment, the sanding head connection assembly  110  includes the planetary gear reduction system  152  for imparting more than one type of motion to the sanding system. An exemplary planetary gear reduction system  152  is illustrated in  FIGS. 5A and 5B . In the exemplary embodiment, the planetary gear reduction system  152  includes a shaft  154  with a sun gear  156  and a plurality of planets  158  contained within a ring gear  160 . Further, the shaft  154  with the sun gear  156  includes a first drive member  162  and a second drive member  164 . In such embodiment, the sun gear  156  is surrounded by a first planet  166 , a second planet  168 , and a third planet  170 , each of which is threaded thereby allowing the planets to be coupled with the ring gear  160  and the sun gear  156 . It is contemplated that the plurality of planets  152  may be coupled to the ring  160  and the second drive member  164  via pins disposed within the second drive member  164 . This arrangement allows the axis of the output gear to be approximately equivalent to that of the input gear. In addition, use of three planets instead of one yields a gear train capable of withstanding a great deal of use and strain. Further, the described configuration provides a planetary gear reduction system capable of imparting both rotational and orbital motion to the sanding head. It is contemplated that additional gear configurations may be employed without departing from the scope and spirit of the present invention. 
   In use, the present invention forms a two-stage planetary gear system. First, the first drive member  162  including the sun gear  156  is employed to drive a orbital sanding head  140  at a suitable speed (e.g. to spin at 6000 rpm). For example, an orbital sanding pad head may includes an eccentric recess and the first drive member drives a pin which drives the eccentric recess to create orbital motion. Second, the second drive member  164  is driven by the planets to provide the speed necessary to drive a rotational head  138  at a suitable speed (e.g. 2000 rpm). In one embodiment, a three to one ratio of speeds is employed whereby the sun gear  156  turns at 6000 rpm to drive the orbital sanding head  140  and the second drive member  164  turns at 2000 rpm to drive the rotational head  138 . 
   As illustrated in  FIG. 7 , a circular shaped sanding head  138  may be connected to the sanding head connection assembly  110  for rotational sanding. In an alternative embodiment, as illustrated in  FIG. 8 , a rectangular shaped or orbital sanding head  140  may be connected to the sanding connection assembly  140  for orbital sanding. It is contemplated that additional shapes of heads may be employed including triangular without departing from the scope and spirit of the present invention. 
   In an exemplary embodiment, the positioning of the sanding head on the sanding head connection assembly  110  is determined by the shape and size of the inner diameter of the connector  146  defined on a sanding head. As described previously, the outer diameter of the connector  146  may be approximately equivalent in shape and size on the various sanding heads, allowing the adapter  136  and the desired sanding head to be connected efficiently. In contrast, the shape and size of the inner diameter of such connector  146  may vary depending upon the type of motion (e.g., rotational or orbital) the sanding assembly  108  is to impart. For example, as illustrated in  FIG. 6A , the inner diameter of the connector  146  on the rotational or circular shaped sanding pad  138  is circular and a plurality of teeth travel along the perimeter of the circle. The plurality of teeth assist in positioning the rotational shaped sanding pad  138  with the sanding head connection assembly  110  so that the planetary gear reduction system  152  is capable of imparting rotational motion to the rotational sanding pad head  138 . The positioning of the rotational sanding pad head  138  relative to the various components of the sanding head connection assembly  110  is illustrated in  FIGS. 9 through 11 .  FIG. 9  demonstrates a sanding head connection assembly  110  without a sanding head attached.  FIGS. 10 and 11  illustrate the sanding head connection assembly  110  with the rotational sanding head  138  connected to the assembly  110 . In addition, as illustrated in  FIG. 6B , the inner diameter of the connector  146  disposed on the orbital sanding pad head  140  is also circular; however, the perimeter of the circle is smooth and an extension extends up through the center of the circle. Such configuration allows the orbital sanding head  140  to align with the planetary gear reduction system  152  so that the sanding head connection assembly imparts orbital motion to the orbital sanding pad  140 . 
   Although the present disclosure describes a sander for removing drywall, it is contemplated that such sander may be utilized to removed additional types of materials including plaster, concrete, wood, and the like without deviating from the scope and spirit of the present invention. 
   It is believed that the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in size, materials, shape, form, function, manner of operation, assembly and use 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.