Abstract:
A power tool in accordance with the invention includes a housing having an internal compartment with a motor therein, a handle connected to the housing for maneuvering the power tool, a working element connected to and driven by the motor to work on a workpiece, and a removable, portable power source having a first position wherein the power source is located primarily in the internal compartment of the housing and being electrically connected to the motor to provide power to the motor for driving the working element and a second position wherein the power source is located remotely from the housing and detached electrically from the motor. A preferred embodiment of the tool also includes a lock associated with the apparatus which has a lock position that prevents the removable, portable power source from unintentionally becoming separated from the power tool, and an unlock position that enables the removable portable power source to be selectively removed from the internal compartment of the housing and separated from the power tool. A preferred embodiment of the power tool includes the use of a rechargeable, removable, portable power source and an electrical connector which allows the power tool to be powered by an alternate power source located externally of the power tool.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to a power tool having a removable, portable power source and, more particularly to a hand held polisher having a removable, portable power source in association with its housing. 
   BACKGROUND OF THE INVENTION 
   The tool industry offers a variety of cordless power tools for performing work on various types of workpieces. Each of these tools offer the advantage of being operated without a cord and/or remote from a generator or a hard wired power source, such as a conventional outlet. For example, cordless power tools allow the tool operator to use the tool without regard for both the proximity to a power outlet or to the length of available power. Battery-powered tools also allow the tool operator to operate the tool without interference and distracting concerns associated with an attached power cord. 
   Known power tools commonly locate the battery at the handle of the tool. This often tends to make the tool unbalanced and cumbersome to operate due to the unbalanced and oversized weight distribution. For example, a 14.4-volt or 18-volt battery located at the end of a power tool handle increases the weight distribution such that the tool becomes difficult to hold and operate steady for appropriate periods of time due to operator fatigue. This is of particular concern when working with generally vertical workpieces, such as a car door, as opposed to generally horizontal workpieces, such as a board laying flat on a workbench. 
   Experience also has revealed that an unbalanced tool renders it difficult to work evenly on a workpiece. For example, in the case of polishers, it is important to apply wax evenly over the workpiece and to polish and buff the workpiece evenly thereafter. If the power tool is unbalanced, the task of working the tool evenly about the workpiece becomes more difficult for the operator and has the tendency to make the tool work heavier on the side nearest the battery (the heavier portion of the tool). 
   Another shortcoming associated with handle located batteries is the tendency to require the handle to be larger than necessary. This compounds the difficulty and discomfort in holding the tool. For example, the size of a conventional battery pack often increases the handle size by at least 30 percent. The enlarged handle configuration tends to render the power tool more difficult and uncomfortable to handle. 
   An even further shortcoming with handle-mounted batteries is the limitation on the ability to provide a variety of gripping locations. For example, the addition of a battery pack to the handle often shortens the length of the portion of the handle on which one can grip. This results in reducing the number of different gripping positions on the handle. 
   Since a wide variety of individuals will be using the power tool, the shortcomings from having the battery pack in the handle make it difficult to meet the variety of demands each operator may have for the power tool. 
   Thus, there is a need for a power tool having a portable power source to enable the tool to be used in a variety of locations for a variety of different applications and in a convenient, efficient and effective manner. 
   SUMMARY OF THE INVENTION 
   A power tool in accordance with the invention includes a housing having an internal compartment with a motor therein, a handle connected to the housing for maneuvering the power tool, a working element connected to and driven by the motor to work on a workpiece, and a removable portable power source having a first position wherein the power source is located primarily in the internal compartment of the housing and being electrically connected to the motor to provide power to the motor for driving the working element and a second position wherein the power source is located remotely from the housing and detached electrically from the motor. A preferred embodiment of the tool also includes a battery release mechanism or lock associated with the housing and the removable portable power source. The lock has a lock position that prevents the removable portable power source from unintentionally becoming separated from the power tool, and an unlock position that enables the removable portable power source to be removed from the internal compartment of the housing and separated from the power tool. The lock may be connected to the housing and configured such that it remains connected to the housing when the removable portable power source is removed from the internal compartment, or may be connected to the removable portable power source and configured such that it remains connected to the removable portable power source when the removable portable power source is removed from the internal compartment of the housing. 
   The housing may also include a detachable portion that detaches at least in part from the housing to enable the removable portable power source to be selectively removed from the internal compartment of the housing. In a preferred embodiment, the detachable portion of the housing is attached to the removable portable power source and detaches entirely from the housing when the removable portable power source is removed from the internal compartment of the housing. 
   Ideally, the power tool will use a rechargeable removable portable power source so that the removable portable power source may be reused with the power tool. As such, the power tool may be configured with an electrical connector which is electrically connected to the motor for enabling the motor to be powered by an alternate power source located externally of the power tool when the removable portable power source is dissipated, or when the operator so desires to operate the power tool from an alternate power source. For example, the power tool may be connected via a power cord to an alternate power source located externally of the power tool. The alternate power source may be rechargeable and/or may require the use of a converter to convert the power output of the alternate power source from a first type of power to a second type of power for powering the motor. 
   The power tool may also include an outer elastomer surface, such as an elastomer injected overmolding, to facilitate enhanced gripping for control over the power tool. The handle may also be generally U-shaped to allow an operator a range of locations about the housing to facilitate an effective two-handed grip to maintain control over the power tool. In one embodiment, the handle may be designed with first and second end portions that are enlarged with respect to the remainder of the handle in order to provide the operator with a variety of grip sizes to choose from. 
   The power tool may also include an actuator electrically connected to the motor for activating and deactivating the power tool. The actuator may be positioned in a bridging member which connects the handle and the housing of the power tool, or may be recessed in the bridging member connecting the handle and the housing of the power tool in order to prevent accidental actuating thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a power tool embodying the features of invention; 
       FIG. 2  is a front elevational view of the power tool of  FIG. 1 ; 
       FIG. 3  is a left-side elevational view of the power tool of  FIG. 1 ; 
       FIG. 4  is a right side elevational view of the power tool of  FIG. 1 ; 
       FIG. 5  is a plan view of the power tool of  FIG. 1 ; 
       FIG. 6  is an exploded view of the power tool of  FIG. 1 ; 
       FIG. 7  is a cross sectional view of the power tool of  FIG. 1  taken along line  7 — 7  in  FIG. 3 ; 
       FIG. 8  is a cross sectional view of the operated power tool of  FIG. 1  taken along line  8 — 8  in  FIG. 2 ; 
       FIG. 9  is an enlarged view of a portion of  FIG. 8  to illustrate a power source release mechanism; 
       FIG. 10  is a cross-sectional view of the power tool of  FIG. 1  taken along line  10 — 10  in  FIG.2 ; 
       FIG. 11  is a perspective view of an alternate power tool embodying features of the present invention; 
       FIG. 12  is a front elevational view of the power tool of  FIG. 11 ; 
       FIG. 13  is a right-side elevational view of the power tool of  FIG. 11 ; 
       FIG. 14  is a plan view of the power tool of  FIG. 11 ; 
       FIG. 15  is an exploded view of the power tool of  FIG. 11 ; 
       FIG. 16  is a cross-sectional view of the power tool of  FIG. 11  taken along line  16 — 16  in  FIG. 12 ; 
       FIGS. 17A–D  are perspective views of alternate power source release mechanisms embodying feature of the present invention; 
       FIG. 18  is a perspective view of an alternate power tool in accordance with the invention showing a modular power cord; and 
       FIG. 19  is a bottom view of the power tool of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In  FIGS. 1–10 , there is illustrated a power tool  10  with a portable power source for working on a workpiece (e.g., waxing, buffing, polishing, etc.) in accordance with the present invention. The power tool  10  includes a housing  12 , a generally U-shaped handle  14  connected to the housing  12 , and a work element, such as a pad  16 , for working on a desired workpiece, such as the body of a automobile or hull of a boat. The power tool  10  includes a symmetrical design about a vertical reference plane (not shown) extending centrally from a forward end  18   a  to a rearward end  18   b  (see  FIGS. 3 and 4 ). The cross section illustrated in  FIG. 8  is taken along the vertical reference plane. 
   The housing  12  includes an upper housing shell  20  and a lower housing shell  22  which, when connected to each other, interface along a part line  24 . The upper housing shell  20  and lower housing shell  22  can be made of any suitably lightweight material and are preferably molded plastic parts. The upper housing shell  20  and the lower housing shell  22  are secured together by a number of screws recessed in the lower surface of the handle  14 . Collectively the upper and lower housing shells  20  and  22  define an internal cavity  26 . A motor  28  is disposed in the cavity  26  and is connected to a motor or gear mounting plate  30  also located within cavity  26 . The mounting plate  30  is preferably secured to the inside of the lower housing shell  22 . 
   The motor  28  is mechanically connected to the pad  16  and is capable of driving the pad  16  in an orbital path below the housing  12 . More particularly, a motor output shaft  28   a  drives a first gear or pinion gear  32 , which, in turn, drives a second gear or driven gear  34 . The gears  32  and  34  are at least partially covered by gear casing or cover  42  in order to protect the gears from contaminants, such as dust or other residual particles from materials, such as wax, which are used on the workpiece in conjunction with the tool  10 . A gear shaft  36  has a first end connected to the driven gear  34  and a second end to a counterweight  38 . Rotation of the gear shaft  36  results in rotation of the counterweight  38  about the shaft  36 . Moreover, rotation of counterweight  38  causes a corresponding rotation about the z-axis of the work element such as pad  16 , which is connected to the counterweight  38 . Bearings  40   a–d  are used to reduce the friction of the rotating members and allow the motor to operate more efficiently. 
   The housing  12  further defines a power source compartment  44  for holding a removable power source such as battery or battery pack  46 . For example, as illustrated in  FIG. 6 , the removable power source  46  includes a lower battery pack housing  46   a , multiple battery cells  46   b , and an upper battery pack cover  46   c . The battery pack housing  46   a  is complimentary shaped to fit within the housing  12 , and includes a lower protruding member  46   d  extending downward from and below the lower housing  46   a . When assembled, the battery cells  46   b  are inserted into the lower housing  46   a , which is attached to the cover  46   c  via fasteners, such as screws  46   e . The battery pack lower housing  46   a  is generally U-shaped or V-shaped with the protruding member extending downward below the general apex region of the U or V-shaped portion. The battery-style power source  46  is preferably designed to hold ten 1.2-volt cells and two dummy cells to produce a 12-volt power source, or twelve 1.2-volt cells to produce a 14.4-volt power source. In each instance, two cells are stored side-by-side in the lower protruding member  46   d . This configuration allows for two separate models of the tool  10  to be provided from the same platform, thereby reducing the costs associated with offering multiple models. 
   The contacts or terminals  55  for the power source  46  are located on the bottom and/or lower side surfaces of the protruding member  46   d , and are positioned to engage corresponding electrical contacts, such as spring contacts  56 . The contacts  56 , for example, are mounted on a printed circuit board (PCB)  58 , which is connected to the inside of the power source compartment. This configuration allows conventional battery pack-type terminal configurations to be used, thereby further reducing the cost associated with manufacturing the apparatus  10 . 
   The inside surface of the battery compartment  44  is separated from the internal cavity by a plastic lining wall or liner  48 , which is configured to closely correspond to the shape of the power source pack  46 . The shape of the liner  48  aids to properly guide the power source in and out of the compartment  44 . For example, with reference to the embodiment illustrated in  FIG. 6 , the battery pack  46  can only be inserted into the compartment  44  with one orientation, i.e., with the protruding member of the housing  46   a  extending downward and the U or V-shape of the battery pack housing  46   a  matching the corresponding curved shape of the liner  48 . Such configuration eliminates operator confusion with respect to installing the battery pack  46  and inadvertent or accidental electrical issues due to handling and installation of the battery pack  46 . 
   The upper housing shell  20  includes an inner surface  20   a  which extends inward to combine with at least a portion of liner  48  to define a generally oval shaped recess to receive the protrusion  46   d  of battery pack  46 . The electrical contacts or terminals  56  are located near the bottom of the recess  46   f , where the PCB  58  is connected to a lower tongue portion of the liner  48 . The remote location of the terminals  56  renders it even more difficult to improperly install and connect the battery  46  to the tool  10 . 
   The power source  46  and the upper housing shell  20  interface at a parting line  50  when the power source  46  is properly associated with the tool  10 . The parting line  50  runs about the periphery of the opening to the power source compartment  44 . In other words, the parting line  50  defines the outer periphery of the cover  46   c  when the power source  46  is installed. The power source  46  is released by operating the release mechanism or lock  52  located on the top of the housing  12  adjacent the parting line  50 . By actuating the release mechanism  52 , a lock member is removed from engagement with a lock engaging surface so that the power source  46  can be removed from housing  12 . 
   As illustrated in  FIGS. 6 ,  8  and  9 , the power source  46  is removed by sliding a button portion  52   a  of the release mechanism  52  toward the rear  18   b  of the housing  12 . This sliding,action causes a shoulder or hook portion  52   b  to disengage the lock engaging surface or lip  52   c  of power source  46 . The shoulder portion  52   b  is normally biased to a lock position by a spring member  53  positioned between a vertical wall  48   a  of the liner  48  and a vertical wall  52   d  extending downward from the button portion  52   a  of the release mechanism  52 . The length of travel of the button portion  52   a  in the locking direction is limited by an end stop  48   b  which also extends upward from the liner  48 . This action maintains the spring  53  under a minimal amount of compression so that it remains in position between the vertical walls  48   a  and  52   d , including when the power source  46  has been removed from the tool  10 . Thus, when the release mechanism  52  is actuated the button portion  52   a , shoulder  52   b  and vertical wall  52   d  are moved in the direction of the reference arrow  57 . As a result, the spring  53  is compressed, and the shoulder  52   b  disengages the lip portion  52   c  so that the power source  46  can be removed from the tool  10 . A guide member  52   e  extends out from the front of the button portion  52   a  and travels between the top end of the vertical wall  48   a  and another surface on the inside of the upper housing shell  20  to guide the movement made by the release mechanism  52  in a generally linear fashion. 
   Once the release mechanism  52  has been actuated, the operator may remove the power source  46  by grasping the shoulder or gripping grooves  54  ( FIG. 2 ) of the power source  46 , which are formed along the sides of the raised portion  60  of cover  46   c . The gripping grooves  54  form an ergonomic handle which the operator may use to pull the power source  46  from the tool  10 . In a preferred form, the spacing between the gripping grooves  54  tapers toward one another as they extend from the rear  18   b  of the housing  12  to the front  18   b  of the housing. This provides a grip of varying widths to accommodate operators with differing hand sizes. The raised portion  60  also tapers downward as it approaches the front of the housing  18   a  so as to become generally flush with the top edge of the housing  12  at the front of the tool  10 . To assist in the removal of the power source  46 , the button portion  52   a  defines an inclined recessed area  52   r  which facilitates an operator&#39;s ability to efficiently and effectively actuate the release mechanism  52   a . Thus, the power source  46  can be removed with a single hand. For example, an operator may press or slide the release switch  52  with his or her index finger and grasp the gripping grooves  54  with the thumb and remaining fingers. Alternatively, the operator may remove the power source  46  by grasping or palming the outer surfaces of the power source with his or her hand and actuating the release mechanism  52  with either the index finger on the same hand or with a finger or thumb from the other hand. In addition, the power source  46  may further include indentation or grooves  84  which provide enhanced engagement surfaces for the operator to position his or her fingers on the battery cover  46   c  to facilitate effective removal and installation of the power source  46 . 
   When the power source  46  is installed, the spring action of the release mechanism  52  allows the power source  46  to snap into its secure position in the housing  12 . More specifically, the shoulder  52   b  and the lip portion  52   c  of the release mechanism  52  have cooperating cam surfaces so that when the shoulder  52   b  is moved a sufficient amount, the lip portion  52   c  passes below the shoulder when the power source  46  is installed into the housing  12 . Once the lip  52   c  has cleared the shoulder  52   b , the spring  53  biases the shoulder  52   b  into engagement with the lip  52   c  so that the power source  46  is secured in the housing  12 . The power source  46  also has at least one tongue member or post  86  for inserting into a mating recess located on the housing  12  to help secure and align the battery pack  46  in the housing  12 . As illustrated in  FIGS. 6 and 8 , a preferred form of tongue member  86  has a rectangular cross-section and a tapered tip for sliding in and out of a cooperating aperture  86   a  defined by the housing shell  20 . The tapered tip enables effective insertion of the tongue member  86  into the recess  86   a . Other tongue members or alignment tabs may be positioned about the power source  46  in order to help align and/or secure the power source  46  in the housing  12 . For example in  FIG. 6 , additional tabs appear on the side of the power source  46  to assist the tongue  86 . In alternate embodiments, the tongue and/or tabs may extend from the housing  12  and the recesses may be defined by the power source  46 . In even other embodiments, a combination of tongue and/or tab members and recesses may appear on both the power source  46  and the housing  12 . 
   As illustrated in  FIGS. 1–10 , the remainder of the upper housing portion  20  is contoured to coordinate with the cover  46   c  of power source  46 . For example, the sidewalls of the upper housing shell  20 , which define the battery compartment  44  opening and form part of mating line  50 , are arcuately shaped to match the corresponding sidewalls of cover  46   c . Furthermore, the rear sidewall of the upper housing shell  20  contains recesses or shoulder portions which correspond to the gripping portions  54  of the cover  46   c.    
   The lower housing shell  22  is generally bowl-shaped with a planar bottom wall  22   a . An arcuate shield or skirt  74  is attached to the bottom wall  22   a  by screws  75 . As illustrated in  FIG. 7 , the upper and lower housing shells  20  and  22  are connected in a tongue and groove fashion along the parting line  24  and, when mated together, define the internal cavity  26  to house the motor and gearing. The lower wall  22   a  ( FIG. 19 ) of the lower housing shell  22  and the shield member  74  each define an opening  22   b ,  74   a , respectively, which are aligned and through which at least a portion of the gear/motor mount  30  passes. 
   As illustrated in  FIGS. 6 and 8 , the gear/motor mount  30  has a lower planar portion  68  with a frusto-conical portion  70  extending downward therefrom, and an annular wall portion  72  extending upward therefrom. The frusto-conical portion  70  defines a hollow inner region in which bearings  40   a  and  40   b  are disposed, and a passageway for the gear shaft  36 . Due to an internal shoulder portion  77  in the frusto-conical portion  70 , and the counterweight  38 , the bearings  40   a–b  are retained in the hollow region and the shaft  36  is allowed to pass through the portion  70 . The planar portion  68  of the mount  30  is attached to the lower housing shell  22  such that the frusto-conical shaped portion  70  and the gear shaft  36  extend through the opening  22   b  defined by the lower wall  22   a  of the lower housing shell  22  and the opening  74   a  defined by the shield member  74 . The gear/motor mount  30  and shield member  74  are fastened to the lower wall of the lower housing shell  22  by fasteners, such as the screws  75 . 
   The annular wall portion  72  of the gear/motor mount  30  defines a main cup portion to hold the driven gear  34  and defines a smaller secondary cup portion, adjacent the main cup portion, to hold the pinion gear  32  such that their teeth are intermeshed with one another. As an example, the tool  10  has a 4.56:1 gear ratio in order to step down the roughly 18,000 revolutions per minute (RPM) capable of being generated by motor  28  to approximately 2,400–4,000 RPM. This results in a significantly higher torque output than is currently available in the marketplace. 
   As mentioned above, the gear shaft  36  is connected to the driven gear  34 . More particularly, the upper end of the gear shaft  36  is polygonal in shape and extends through a central opening in the driven gear  34 , which is of a complementary polygonal shape so that rotation of gear  34  also rotates the shaft  36 . For example, the upper end of the gear shaft  36  preferably has a generally rectangular cross-section, and the opening in the gear  34  is of a complementary sized, generally rectangular cross-section. Thus, rotation of the gear  34  results in a corresponding rotation of the gear shaft  36 . 
   A stop  76 , such as a ring, clip or pin, is fitted on the upper end of the gear shaft  36  extending beyond the gear  34  in order to prevent the gear shaft  36  from sliding out of engagement with the gear  34 . For example, if a ring or clip is employed, such as a C-clip or E-clip, the gear shaft  36  has an annular groove about the end portion of the shaft that extends above the gear  34  so that the ring or clip  76  can be connected to the shaft  36 . 
   Below the driven gear  34 , the gear shaft  36  takes on a larger, circular cross-section creating a shoulder to support the gear  34  from below. This configuration limits the amount the shaft  36  can be inserted into the central opening of the gear  34 , allows the shaft  36  to better fit the circular openings of the bearings  40   a–b , and reduces friction caused by the rotation of the shaft  36 . The lower end of the gear shaft  36  is threaded to enable a threaded engagement with the counterweight  38 , as discussed in further detail below in connection with the work element  16 . 
   The gear cover or casing  42  is connected to the gear/motor mount  30  and is positioned over a majority of the annular wall  72  like a sleeve in order to aid in sealing the gears  32  and  34  and associated grease from contaminants. More particularly, the casing  42  forms a generally cylindrical sleeve over the driven gear  34  and has a raised center portion to accommodate the portion of the gear shaft  36  which extends slightly above the driven gear  34  and the associated stop  76 . The casing  42  also has a semicircular notch  42   a  formed in the side adjacent the smaller secondary cup portion of the annular wall  72  to provide clearance for the motor shaft  28   a  and pinion gear  32 . The notch  42   a  has a sidewall  42   b  extending upward therefrom which further serves to support and space the motor  28  with respect to the casing  42  and the gear/motor mount  30 . The casing  42  is secured to the gear/motor mount  30  via fasteners, such as screws  31 , which are thread into threaded columns or bores  33  attached to the outer sidewalls of the casing  42 . 
   A plurality of support gussets  79  and hollow posts  81  also extend from the planar portion  68  of gear/motor mount  30 . The hollow posts  81  are internally threaded and are used to mount the gear/motor mount  30  to the housing  22  and secure the motor  28  on the support gussets  79 . With this configuration, the internal mechanisms of the tool  10 , such as the motor  28 , the gears  32  and  34  and the gear shaft  36 , are held in operating position and reduce the occurrence of undesirable vibration when the tool is operated. 
   The handle  14  has a generally round cross-section and is generally U-shaped in order to provide the operator with a plurality of locations to facilitate an effective two-handed grip to maintain control over the tool  10 . More particularly, upper and lower handle portions  14   a  and  14   b  connect along the part line  24  in a tongue and groove fashion and are secured together by screws  23  or other fasteners which are inserted into recessed bores located in the lower portion  14   b  of the handle  14 . The handle  14  is preferably bowed, as best seen in  FIG. 3 , so that the ends  14   c  of the handle  14  dip slightly downward to form a more comfortable gripping region for the operator. In addition, the ends  14   c  of the handle  14  are enlarged with respect to the remainder of the handle  14  and have an outer elastomer surface or grip  88  to facilitate enhanced gripping for control over the tool  10 . For example, as shown in  FIG. 3 , the lower surface of the handle end  14   c  is curved in a convex manner to provide an enlarged gripping surface or enlarged handle portion. 
   Both the enlarging of the handle ends  14   c  and the bowing of the handle  14  provide the operator with a multi-dimensional handle which offers greater control over the tool than traditional handles in the market place. For example, the enlarged ends  14   c  offer the operator greater control over the tool  10  by increasing the surface area of the handle thereby allowing the operator to use more of his or her hand to grip the tool and to maintain a stronger grip thereon. The enlarged ends  14   c  also allow the operator to maintain a forward grip on the end of the handle which may assist the operator in drawing the tool  10  back towards the operator. In addition, the enlarged ends  14   c  allow the operator to “feel” the ends of the handle without the need to visually locate them. This allows the operator to frequently focus on the workpiece while grasping the tool rather than requiring the operator to break visual contact with the workpiece to determine where the ends of the handle  14  are. The enlarged ends  14   c  also provide the operator with a physical and visual end stop about which the operator knows he or she can not move beyond. Furthermore, the enlarged ends  14   c  position the operators hands when grasped in locations which are generally centrally balanced with respect to the tool  10  and generally balanced about the tools center of gravity. Thus, this provides the operator with a more comfortable, secure and strong grip of the tool  10 . 
   The elastomer grip  88  is provided on both the upper and lower portions  14   a  and  14   b  of the handle  14  and is preferably added via an injection overmolding process. More particularly, the handle  14  is preferably formed by a plastic injection molding process, which is later followed by injection of a grip layer material to form grip  88 . A preferred material for the elastomer grip is an elastomer/plastic blend, such as, for example, SANTOPRENE, which is a product of Advanced Elastomer Systems, L.P. of Akron, Ohio. The overmolded grip may be formed with a smooth outer surface or with a textured outer surface and provides a non-slip rubber (or rubber-like) gripping surface for the operator&#39;s hand to grasp. Preferably, the operator will grip the ends  14   c  of the handle  14  with his or her palm covering the grip  88  on the upper handle portion  14   a  and his or her fingers and thumb wrapping around the handle to grasp the grip  88  on the lower handle portion  14   b . Alternatively, however, the operator may grasp the handle along any of the plurality of locations about the U-shaped handle. Furthermore, in alternate embodiments of the invention, additional portions of the handle  14  (or the entire handle) may be covered with an elastomer overmolding. For example, an overmolded grip portion may be included in the rear of the unit near the actuator switch. 
   It should be understood that other materials may be used for the overmolded gripping portions  88 . For example, other thermal plastic elastomers or elastomer/plastic blends, such as rubber, nylon, butyl, EPDM, poly-trans-pentenarmer, natural rubber, butadiene rubber, SBR, ethylene-vinyl acetate rubber, acrylate rubber, chlorinated polyethylene, neoprene and nitrile rubber, may also be used for the overmolded grip  88 . Another material which may be used for the overmolded grip  88  is HERCUPRENE, which is manufactured by the J-Von company of Leominster, Mass. 
   It should also be understood that alternate embodiments of the apparatus may be provided with no elastomer overmolding whatsoever. For example, the tool  10  may be provided with a simple smooth or textured plastic handle created from a traditional plastic injection molding process. More particularly, in a preferred embodiment, the overmolded grip surfaces  88  of handle  14  are replaced with a textured surface such as Rawal#MT-11605, a mold texturization process provided by Mold-Tech/Rawal of Carol Stream, Ill. Similarly, other mold texturization processes may be used to create a variety of textured surfaces. 
   The handle  14  is connected to the upper and lower housing shells  20  and  22  of the housing  12  by three spoke-like members  62   a, b  and  c . The spokes  62   a–c  are generally rectangular in cross-section and have a generally hollow interior to conserve on material cost and reduce the overall weight of the tool  10 . The preferred spokes  62   a–c  extend integrally from the upper and lower housing shells  20  and  22  of the housing  12  and, thus, are separated into upper and lower portions  64   a–c  and  66   a–c  separated by parting line  24 . The upper spoke portions  64   a–c  are integrally connected to upper housing shell  20  and upper handle portion  14   a , and the lower spoke portions  66   a–c  are integrally connected to lower housing shell  22  and lower handle portion  14   b . Furthermore, as with the upper and lower housing shells  20  and  22  and the upper and lower handle portions  14   a  and  14   b , the upper and lower spokes  64   a–c  and  66   a–c , respectively, are preferably mated with a tongue and groove configuration along the part line  24 . 
   As illustrated in  FIGS. 5 ,  6 ,  8  and  10 , an actuator, such as a rocker switch  90 , is positioned at the top of the middle spoke  62   b , which is centrally located in the rear of the tool  10  adjacent the handle  14 . A switch cover  92  is positioned over the top of the switch  90  and encloses the switch  90  in order to prevent dust or other residual particles from interfering with the switch&#39;s operation. The switch cover is preferably a rubber cover. 
   The switch  90  snaps into a mounting plate  91 , which, in turn, is fastened to the tool  10  by screws  93  or other similar fasteners. More particularly, the switch cover  92  is sandwiched between the switch  90 , the mounting plate  91  and the inner surface of the bridging member  62   b . In order to reduce accidental or inadvertent operation of the tool  10 , the switch  90  is bounded on two sides by wall-like structures  96 , which extend upward from the rear portion of the spoke (behind the switch  90 ) and to the sidewalls of the housing  12  (in front of the switch  90 ). The wall-like structures  96  preferably are formed integral with the spoke portion  62   b  and the housing  12 . In alternate embodiments, the same function would be achieved by extending the side walls or wall-like structures  96  from the handle  14  to the sidewalls of the housing  12 , or by recessing the switch  90  further into the spoke  62   b.    
   As illustrated in  FIGS. 6 ,  8  and  19 , the rear spoke  62   b  includes a power connector  94 , such as a jack, for supplying an alternate means of power to the tool  10 , (i.e., for supplying power to the apparatus from a power supply external to the power tool). The rear spoke  62   b  also includes a strain relief  95  comprised of two tab members  95   a  and  95   b  partially covering a recess  95   c  and defining an S-shaped opening into the recess  95   c . A power cord can be fed into the recess  95   c  through the S-shaped opening and held in the recess  95   c  by the tabs  95   a  and  95   b  to prevent the power cord from accidentally being disconnected from the connector  94 . One end of the power cord includes a plug that fits complementarily into the connector  94  so that the tool  10  may continue to be used even when the power source  46  is dissipated. The various alternate power supplies and ways in which the apparatus can be connected thereto will be discussed further below with respect to  FIG. 18 ; however, regardless of which power supply is used, the switch  90  will be electrically connected between the motor  28  and the power supply of choice. Thus, when the switch  90  is placed into the “on” position, power will be supplied to the motor  28  in order to drive the work element  16  connected to the tool  10 . When the switch  90  is placed into the “off” position, no power will be supplied to the motor  28 , and the apparatus will remain in an inoperative state. 
   The hollow configuration of the body  12 , spokes  62   a–c  and handle  14  allow for a variety of alternate embodiments to be made. For example, in one alternate embodiment, the actuator  90  may be located in either of the other spokes  62   a  and  62   c  or in a portion of the handle  14 . In another embodiment, the connector  94  for the external power supply may be located on the housing  12  or handle  14  of the tool  10 . 
   The lower end of the gear shaft  36  extends into the shield member  74  and is threaded into a first threaded bore  38   a  defined by the counterweight  38 . The counterweight  38  is connected to the pad assembly  78  by a bolt  80 , which threads into a second bore  38   b  in the counterweight  38 . The second counterweight bore  38   b  is parallel to, and located generally adjacent to, the first counterweight bore  38   a . Thus, rotation of the gear shaft  36  results in a corresponding rotation in the counterweight  38  and the pad assembly  78  connected thereto. The pad assembly  78  preferably consists of a pad support  78   a , a first pad  78   b , a second pad  78   c  and a third pad  78   d . The pads  78   b–d  are overlaid and connected to one another and to the pad support  78   a  by an adhesive and, preferably, include a closed polyethylene pad, an ether foam pad, and a closed micro-cell polyethylene pad, respectively. 
   The pad support  78   a  has a generally planar disc portion  78   e  supporting a frusto-conical portion  78   f  extending upward from the middle and an annular wall  78   g  extending upward from the disc portion  78   e , about the frusto-conical portion  78   f . The annular wall  78   g  is positioned intermediate of the outer periphery of the disc  78   e  and the frusto-conical portion  78   f and, preferably, about two-thirds of the radial distance from the center of the disc  78   e  toward the periphery of the disc  78   e . Thus, the counterweight  38  will rotate within the annular wall  78   g  of the pad support  78   a , and the annular wall  78   g  remains under cover of the shield  74 . The skirt member  74  and the annular wall  78   g  of the pad support  78   a  combine to prevent direct access to the counterweight  38 . 
   The frusto-conical portion  78   f  of pad support  78   a  has a hollow center region that houses the bearings  40   c  and  40   d  and a spacer  98 . The bolt  80  passes through the central openings in the bearings  40   c  and  40   d  and the spacer  98  and is threaded into the second bore  38   b  of the counterweight  38 . The first pad  78   b , the second pad  78   c  and the third pad  78   d  also have central openings or passageways through which the bolt  80  passes in order to be threaded into the counterweight  38 . The end of bolt  80  includes an enlarged head to secure the pad assembly  78 , including bearings  40   a  and  40   b  and spacer  98 , to the tool  10 . During operation, the pad  14  will be orbitally rotated about the z-axis of the tool (defined by gear shaft  36 ) when the motor drives the shaft  36  and the counterweight  38 . 
   For maintenance purposes, for example, at least one small opening or notch  78   h  is defined by the annular wall  78   g  of the pad support  78   a  so that a hand tool or other instrument can be inserted into the interior region between the pad support  78   a  and the skirt member  74  to prevent the counterweight  38  from rotating while the bolt  80  is being unscrewed and removed from the counterweight  38 . This enables the pad assembly  78  to be removed from the tool  10  for access to the counterweight  38 , the screws and bolts connecting the skirt member  74  and the other internal components (e.g., the gear/motor mount  30 ) in the housing  12 . Such access may be required to repair or replace parts, including the pad assembly  78  or those parts internal to the housing  12 , the spokes  62   a–c  and the handle  14 . 
   Turning now to  FIGS. 11–17 , there is illustrated an alternate embodiment of tool  10  embodying features in accordance with the present invention. The release mechanism for the power source may be incorporated as part of the power source as opposed to the housing  12  as illustrated in  FIGS. 1–10 . For convenience, features of the alternate embodiment illustrated in  FIGS. 11–16  that correspond to features already discussed with respect to the embodiment of  FIGS. 1–10  are identified using the same reference numeral in combination with an apostrophe (&#39;) merely to distinguish one embodiment from the other, but otherwise such features are equivalent. 
   More specifically, the power source  46   c ′ includes the release mechanism  100 . The release mechanism  100  is located on the top of the power source  46 ′ adjacent the battery pack cover  46   c ′ and the power source compartment parting line  50 ′. The mechanism  100  is a depressable button or paddle portion  100   a , which, when pressed, causes a leg of a resilient release member  100   b  to bow a sufficient amount to release a clip  100   c  attached to the leg from engagement with a lock surface or lip  100   d  formed on the housing  12 ′. The power source  46 ′ is secured to the housing  12 ′ using an alternate tongue member or post  86 ′ ( FIG. 16 ) consisting of a hook or clip portion which is inserted into a mating recess on the housing  12 ′. The post  86 ′ serves the same function as its corresponding part in  FIGS. 1–10 , which is to help secure and/or align the power source  46 ′ with the housing  12 ′. The clip is tapered and the recess is beveled in order to make insertion and removal of the post  86 ′ easier to accomplish. 
   To assist in removing the power source  46 ′, the mechanism  100  has a recessed area  100   r  located at the paddle portion  100   a  to allow the operator to more easily grip and actuate the release mechanism  100 . For example, an operator may palm the cover of the power source  46 ′, or grasp the lip portions  54 ′ with his or her thumb and pinky finger and grip and actuate the release mechanism  100  via the recessed portion  100   r  with his or her index finger, middle finger and/or ring finger. Thus, the operator is able to “feel” when his or her fingers are in the correct position by locating the recessed portion  100   r . Alternatively, the operator may remove the battery pack  46 ′ by using two hands. This configuration also allows the operator to actuate the release mechanism in the same direction the power source  46 ′ is to be removed. Thus, the power source  46 ′ can be removed in one general motion of pressing down and pulling the power source  46 ′ toward the front of the tool  10 . 
   With reference to  FIGS. 17A–D , alternate release mechanisms may be used instead of the sliding switch or push button release mechanisms discussed above. For example, the release mechanism may consist of an alternate sliding switch  102   a , a compressible clip  102   b , locking clips  102   c , latch  102   d  or other like structures. Thus, it should be understood that a variety of different release mechanisms may be used in order to release the power source from the housing. 
   In other alternate embodiments, the housing cover may be separate and distinct from the removable power source so that removal of the power source does not remove a portion of the housing  12 . For example, a portion of the housing located about the power source may operate like a hinged door giving an operator access to the power source and its compartment. Alternatively, a portion of the housing may operate as a removable panel, which can be temporarily separated from the housing to provide access to the power source and its compartment. With either of these configurations, the portion of housing  12  that is moved to gain access to the power source compartment may be replaced on the tool with or without the power source installed. 
   Referring now more specifically to the wiring of the apparatus  10 , it will be noted that the embodiments illustrated use a direct current (DC) configuration for supplying power to the power tool. For example, the battery pack  46  is electrically connected to one terminal of the motor  28  and electrically connected to one terminal of the switch actuator  90 . Another terminal of the switch actuator  90  is electrically connected to the motor  28  so that DC power will be supplied to the motor  28  by turning on the actuator  90 . The apparatus  10  is further wired to include DC jack  94  which allows the apparatus  10  to be operated using an alternate power supply which is electrically connected to jack  94 . The alternate power supply may be another DC power supply (e.g., a 3–25 V power supply) such as a 12 V car battery or generator, or may be an alternating current (AC) power supply (e.g., a 85–265 V power supply), which is connected to a AC-DC converter (or adapter) for converting the AC power into DC power. For example, as illustrated in  FIG. 18 , a power cord  150  may be connected between the DC jack  94  via plug  152  and a DC or AC supply via plug  154 . More particularly, plug  154  may be connected to a cigarette lighter adapter (CLA)  156  which, in turn, is connected to a DC power supply such as a 12 V battery. Alternatively, plug  154  maybe connected to an AC adapter  158  which is connected to an AC power supply, such as a conventional wall outlet in a residence, and converts the AC power to DC power via a AC-DC adapter. 
   Preferably, the apparatus  10  is wired such that the power source  46  can be charged in the housing  12  while the tool is connected to an alternate power supply via power cord  150 . In addition, a charger (not shown) and extra power source can be supplied with the tool  10 , so that one portable power source can be re-charged while the other portable power source is installed in the housing  12 . Thus, when the installed power source becomes dissipated, the operator may continue to use the tool in a cordless fashion by inserting the second power source in the housing and placing the dissipated battery in the charger. The charger may be a separate component or may be connected to one of the power cord  150 , CLA  156 , and AC adapter  158 . 
   Alternatively, the tool  10  may use an AC configuration in which an AC socket or terminal is located on the tool in place of the DC jack so that a power or extension cord can be connected between the apparatus  10  and an alternate AC power supply. The AC terminal located in the housing is electrically connected to a AC-DC converter located within the housing  12  in order to convert the AC power input into DC power which is supplied to the motor  28  to drive a working element, such as the pad  16 . Similar to the configuration discussed above, the tool may be setup to charge the power source in the housing while the tool is plugged into the AC power supply, or charge the power source in an external charger while operating the apparatus using an alternate power supply. 
   Thus, it is apparent that there has been provided, in accordance with the invention, a portable power tool having a removable power source associated with the housing of the tool that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.