Abstract:
A saw having a body, a continuous loop cutting chain, and a chain support extending from the body, the body comprising one or more handles, a motor, and a chain driver. The chain support comprises one or more chain support bars having one or more wheels mounted thereon, each wheel adapted to receive and guide a portion of the chain, at least one wheel of which is mounted at an end of the one or more support bars. The chain support may be pivotable to a desired angle within a range of angles relative to the body. An adjustable guide mechanism may enable setting a maximum distance that the saw blade is able to protrude through a workpiece.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This invention claims priority of U.S. provisional patent application Ser. No. 60/538,572, filed Jan. 23, 2004, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to saws, and more particularly to a chainsaw tool.  
       BACKGROUND OF THE INVENTION  
       [0003]     Chain saws are well known in the art for use primarily for sawing down trees, but also may be used in construction work for sawing boards and the like. Chain saws provide great versatility and speed in cutting operations. One drawback of chainsaws is that the chain tends to turn in a rather wide radius at the end of the saw, thereby limiting the turning radius of the saw for cutting within interior holes in a workpiece. Chain saws are also typically configured such that the user must position the cutting portion of the saw directly in front of his or her body.  
         [0004]     Angle grinders are also well known in the art and typically have a body platform as shown generally in U.S. Pat. No. 5,201,146, assigned to the Makita Corporation of Japan. This type of body platform allows a user to perform cuts on workpieces that may not be directly in front of his or her body. Angle grinders typically only have a circular cutting blade, however, limiting cutting operations to the radius of the circular blade.  
         [0005]     It would be desirable, therefore, to provide a saw that overcomes some or all of the deficiencies of standard chain saws and angle grinders, while combining some or all of the advantages.  
       SUMMARY OF THE INVENTION  
       [0006]     One aspect of the invention comprises a saw having a body, a continuous loop cutting chain, and a chain support extending from the body, the body comprising one or more handles, a motor, and a chain driver. The chain support comprises one or more chain support bars having one or more wheels mounted thereon, each wheel adapted to receive and guide a portion of the chain, at least one wheel of which is mounted at an end of the one or more support bars.  
         [0007]     The one or more chain support bars may extend from a swivel plate pivotably attached to the body and adapted to be fixed at a desired angle within a range of angles relative to the body. The one or more chain support bars may be attached to a chain tension adjusting mechanism mounted to the swivel plate and movable relative to the swivel plate to extend the one or more chain support bars inward or outward relative to the chain driver to increase or decrease tension on the cutting chain.  
         [0008]     The saw may further comprise an adjustable guide mechanism for fixing a maximum distance that the saw blade is able to protrude through a workpiece. The adjustable guide mechanism comprises a movable plate for contact with a surface of the workpiece and that is movable relative to a fixed plate that is fixed relative to the central support bar; a brace for connecting the movable plate to the fixed plate; and an adjustment mechanism for manipulating the brace to set a desired distance between the movable plate and the fixed plate. The fixed plate may be mounted to the chain tension adjusting mechanism.  
         [0009]     The one or more chain support bars may comprise an upper support bar and a lower support bar, in which the one or more wheels are mounted between the upper and lower support bars, or the one or more chain support bars may comprise only a single central support bar in which each of the one or more wheels comprises an upper portion and a lower portion between which the central support bar rests. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective view of an exemplary saw of the present invention.  
         [0011]      FIG. 2  is a cross-sectional view of the saw of  FIG. 1  taken along lines  2 - 2 .  
         [0012]      FIG. 3A  is an exploded perspective view of the exemplary saw of  FIG. 1 .  
         [0013]      FIG. 3B  is a perspective view of the underside of driving gear  30  shown in  FIGS. 1 and 3 A.  
         [0014]      FIG. 4  is an exploded perspective underside view of selected components of the saw shown in  FIG. 1 , including the guide and chain-tightening mechanisms.  
         [0015]      FIG. 5  is a cross-sectional view of the guide and chain tightening mechanisms of  FIG. 4 , taken across line  5 - 5  in  FIG. 7 .  
         [0016]      FIG. 6  is a top view of an the guide mechanism in an expanded configuration.  
         [0017]      FIG. 7  is a perspective view of the guide and chain tightening mechanisms of  FIGS. 4-6  and the chain driving gear, with a portion of the chain, upper flange, and lock nut removed for purposes of the drawing.  
         [0018]      FIG. 8  is a side view of a portion of the saw featuring the guide and chain tightening mechanisms with the chain removed.  
         [0019]      FIG. 9  is a bottom view of the saw of  FIG. 1  showing the adjustability of the blade relative to the body by illustrating a straight position in dashed lines and a pivoted position in solid lines.  
         [0020]      FIG. 10  is an exploded perspective view of an alternate chain bar/wheel configuration.  
         [0021]      FIG. 11  is a cross-sectional view of the chain bar/wheel configuration of  FIG. 10 .  
         [0022]      FIG. 12  is a detailed view of the chain bar/wheel configuration shown in  FIGS. 1-9 .  
         [0023]      FIG. 13  is a perspective view of an embodiment featuring the chain bar/wheel configuration of  FIG. 10  and a number of safety features.  
         [0024]      FIG. 14A  is a detailed view of the hand guard shown in  FIG. 13 .  
         [0025]      FIG. 14B  is a perspective view of the chain guard shown in  FIG. 13 .  
         [0026]      FIG. 15  is an exploded view showing the relationship between the chain guard and the chain bar of  FIG. 13 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     Referring now to the figures, there is shown an exemplary saw of the present invention comprising a body  10 , which may comprise a body and motor that is essentially identical in construction to any commercially available angle grinder known in the art. The body may be any type or style, however, and may have beneficial features found on any type of construction tool. What is important, is that the body hold the sawblade and rotate the chain drive gear. The saw further comprises a chain support  12  having a plurality of wheels  18  along which chain  14  rides. Chain  14  may be of any chain-saw chain construction known in the art. Typically, body  10  includes a handle  11 .  
         [0028]     Although not shown in  FIG. 1 , to more easily view the details of the drawing, the saw may further comprise one or more safety guards for safety purposes, as is known in the art, to protect the user from the chain and to keep the chain from being thrown a great distance if the chain starts to come off of the saw. An exemplary set of safety guards is shown in  FIGS. 13-15 .  
         [0029]     In the embodiment shown in  FIGS. 1 and 2 , chain support  12  comprises chain guide wheels  18  mounted on chain guide wheel axles  18   a  between identical upper and lower support arms  20  and  20 ′. Grooves  18   b  in the outer periphery of wheels  18  receive driver teeth  44   a  of chain  14 . More detail of this embodiment is shown in  FIG. 12 , which shows the components of a standard chain  14  known in the art, including driver links  44  having driver teeth  44   a  for being driven by sprocket  30  (shown in  FIG. 3A , for example) and for riding in chain wheel grooves  18   b , and cutter links  42  comprising cutter teeth  42   a  for cutting the work surface. As the chain moves in direction A, the wheels rotate in direction B. The invention is not limited to any particular chain design.  
         [0030]     In an alternate chain support embodiment  112 , shown in  FIGS. 10, 11 , and  13 , wheels  118  may be of a construction in which the wheels comprise an upper portion  118   a  and a lower portion  118   b  between which a central support arm  120  is positioned. Upper portion  118   a  may attach to lower portion  118   b  in any way known in the art, including but not limited to with screws  122  as shown in  FIGS. 10 and 11 . A ball-bearing mechanism  76  of any type known in the art may be mounted within opening  120   a  in arm  120  to allow for smooth rotation of wheels  118 .  
         [0031]     The use of wheels, as opposed to standard grooved chain support known in the art on chain saws, allows for less friction between the driver teeth and the chain support, and also allow for a tighter turning radius at the end of the chain support. Less friction may allow use of less lubrication oil on the chain. Although shown with wheels all along the distance of the chain support, one embodiment (not shown) may comprise just a single chain guide wheel at the end of the chain support, and a standard support bar having a grooved periphery for engaging the driver teeth along the length of the support bar between the drive sprocket  30  and the single chain guide wheel.  
         [0032]     In the embodiment shown in  FIGS. 1 and 2 , width W 1  of chain  14  must be wider than the overall distance from the outer surfaces of arms  20  and  20 ′, whereas in the embodiment shown in  FIGS. 10 and 11 , width W 2  of chain  114  must be wider than the overall distance from the outer surfaces of upper portion  118   a  and lower portion  118   b  of wheels  118 . It should be understood that although many of the figures depict the arm/wheel relationship shown in  FIGS. 1 and 2 , the relationship shown in  FIGS. 10 and 11  may be used instead. It should also be noted that although the  FIG. 1  shows a sizable space between adjacent wheels on the support arm or arms, the wheels may be closer together, such as the relatively minimal distance G shown in  FIG. 13 , in which the wheels almost touch one another, to minimize space over which the chain is unsupported between wheels.  
         [0033]      FIG. 3A  shows the general relationship between the body  10 , chain support  12 , swivel plate  16 , and the chain tightening and guide mechanism. Rounded portion  16   a  of swivel plate  16  fits over axle sleeve  38 , which is a cylindrical protrusion of bearing cover  39 . Swivel plate  16  comprises a screw/clamp mechanism  32  or other tightening means that allow the angle of the swivel plate relative to the body to be adjusted within the range of motion C shown in  FIG. 9 . When screw/clamp mechanism  32  is loosened, the swivel plate may be swiveled to a desired angle and then tightened to fix it in place. Although the swivel plate is a desirable feature, embodiments without such a swivel plate may also be provided, in which the relationship between the chain support and the body is fixed, for example, at the angle shown in  FIG. 3A .  
         [0034]     Chain  14  is driven by sprocket  30 , the underside of which is shown in  FIG. 3B . Sprocket  30  fits over axle  22 , with non-round section  22   a  of the axle interfacing with non-round recess  30   a  in the drive gear. Chain  14  fits around sprocket  30 , with upper flange  26  providing support for the chain as it goes around the sprocket, and lock nut  28  holding the assembly in place on the axle. The chain drive components are not limited to the design schematically shown here, however, and may be of any design known in the art for chain saw assemblies.  
         [0035]     Mounting portion  36  of chain support  12  mounts on swivel plate  16  with post  40   a  mounted through slot  24  and with recesses  62   b  (shown in  FIG. 4 ) aligned with protrusions  62   a  (shown in  FIG. 3A ) of chain tension adjusting mechanism  60 . Body  61  of chain tension adjusting mechanism  60  comprises a C-shaped opening  68  for receiving swivel plate  16 . Nut  40   b  holds down chain support  12  relative to body  61 . With nut  40   b  in a relatively loose configuration, knob  56  may be turned, which rotates worm gear  72 , which turns positioning gear  70 , which protrudes through opening  74  in body  61 . The teeth of positioning gear  70  engage indentations  64  in lower surface  66  of swivel plate  16  to move the chain support  12  in the direction of arrow E (shown in  FIG. 5 ) to tighten or loosen the chain by changing the overall distance between the end of the support arm and chain driving gear  30 . It should be understood, however, that myriad other types of chain adjustment mechanisms can be developed that perform the function of changing the distance between the end chain guide wheel on the chain support and chain drive sprocket  30 , so the invention is not limited to any particular type of chain adjustment mechanism.  
         [0036]     Mounted to the front of chain tension adjusting mechanism body  61  is optionally a guide mechanism  46 , shown in more detail in  FIGS. 6-8 , capable of setting a maximum distance the saw blade will be allowed to protrude through a workpiece. Guide mechanism comprises a guide plate  46   b  that is movable relative to a support plate  46   a . Support plate  46   a  may be attached to chain tension adjusting mechanism body  61  with mounting posts  63   a , which may be threaded to receive fastening nuts  63   b . The support plate may be referred to as being “essentially fixed” relative to the body. By this it is meant that the support plate is fixed relative to the body during the process of adjusting the movable guide plate position. As shown in this particular embodiment, the support plate is actually attached to the chain tension adjusting mechanism, so it is movable within the distance permitted by the chain during the chain tension adjusting process. Nonetheless, the position of the support plate relative to the body is fixed for a given chain of a given length at a given tension.  
         [0037]     The distance D between the guide plate and the support plate, as shown in  FIG. 6 , is set by the position of X-brace  58  mounted between the two plates. X-brace  58  is manipulated by brace-adjusting mechanism  54 , comprising knob  48 , worm gear  50 , and X-brace  58 . X-brace  58  comprises a first member  58   a  comprising driving gear portion  52  and rail-engaging end  53   a . Second member  58   b  comprises a pinned end  55 , which is mounted to plate  46   b  with pin  57   a , and a rail-engaging end  53   b . The first member  58   a  and second member  58   b  are pivotably attached to one another, such as with a pin (not shown) that fits in recesses of both the members, or a pin in one member that fits into a corresponding hole (also not shown). Pin  57   b  mounts first member  58   a  to plate  46   a . Each of plates  46   a  and  46   b  comprise a rail  47  which receives the respective rail-engaging end  53   a  or  53   b  to allow the rail-engaging end to slide relative to the plate  46   a  or  46   b  as the X-brace is expanded or contracted. Rotating knob  48  turns worm gear  50 , which moves driving gear portion  52  of X-brace  58 . The guide mechanism is not limited to the particular mechanism shown here, however, nor is the saw limited to having any such guide mechanism.  
         [0038]      FIGS. 13-15  depict an embodiment comprising a plurality of safety features, each of which may also be present in the other embodiments shown herein, but omitted from the figures for clarity of the details discussion with respect to those figures. Hand guard  78  is provided around handle  11  to guard against a loose chain from kicking back and striking the user in the hand. Chain guard  80  is placed over the mounting portion  112   a  of chain support  112  to keep the chain from completely coming off of the chain support and being thrown when in use, and to further protect the user from the rapidly rotating chain by providing a guard surface  84  that is aligned in a plane parallel to the surface of guide  46 . Chain support  112  comprises a single chain support arm  120 , positioned between upper and lower reinforcing plates  88   a  and  88   b , respectively, in mounting portion  112   a . Chain guard  80  is fastened in place with nut  40   a  and comprises underside slide bars  86   a  and  86   b , which are adapted to contact upper reinforcing plate  88   a  to reduce friction between the guard and the reinforcing plate as the chain support slides back and forth during adjustment. It should be understood that safety guards of any type may be provided, however.  
         [0039]     While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.