Patent Publication Number: US-2006005673-A1

Title: Extendable chain saw system

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to electric power tools and, more particularly, to an extendable power tool system having an extension pole.  
      2. Brief Description of Prior Developments  
      U.S. Pat. No. 5,884,403 discloses a telescoping pole assembly for an electric chain saw. There is a desire to provide an extension pole for an electric chain saw which is easier to attached to the chain saw than conventional extension poles. There is also a desire to provide a connection system between an extension pole and an electric chain saw which is relatively easy and quick to disconnect the two components from each other. There is also a desire to provide an extension pole for an electric chain saw which provides an easier connection system for allowing the chain saw to be actuated by a remote user actuated switch on a rear end of the extension pole.  
     SUMMARY OF THE INVENTION  
      In accordance with one aspect of the present invention, a hand-held electric chain saw is provided comprising a frame forming a housing with a rear end handle; a motor connected to the frame; a chain bar connected to the frame; a saw chain movably mounted to the chain bar and connected by a drive to the motor; and an extension pole attachment system on a bottom surface of the frame adapted to receive a portion of an extension pole to fixedly attach the extension pole to the bottom surface of the frame.  
      In accordance with another aspect of the present invention, a hand-held electric chain saw is provided comprising a frame forming a housing; an electric motor connected to the frame; an electrical connector adapted to be coupled to a power source; a user actuated trigger switch connected to a rear end handle of the housing and adapted to supply electricity from the electrical connector to the motor; and an electrical bypass switch connected to the housing. The electrical bypass switch is adapted to electrically bypass the user actuated trigger switch to supply electricity from the electrical connector to the motor.  
      In accordance with another aspect of the present invention, a power tool extension pole is provided comprising a pole section having a front end and a rear end; a removable connection system at the front end of the pole section; and an electrical cord. The removable connection system comprises a rail adapted to slide into a slot at a bottom of a power tool to thereby mechanically connect the extension pole to the power tool. The electrical cord extends through the pole section and has an electrical connector proximate the front end of the pole section which is adapted to be removably connected to the power tool.  
      In accordance with one method of the present invention, a method of coupling an extension pole to an electric power tool is provided comprising sliding a track at a front end of the extension pole into a slot at a bottom of a housing of the electric power tool; and connecting an electrical connector of the extension pole to the electric power tool. The track slides generally parallel to a bottom surface of the bottom of the housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein:  
       FIG. 1  is an elevational side view of a power tool assembly incorporating features of the present invention;  
       FIG. 2  is a partial, exploded perspective view of the power tool and extension pole of the assembly shown in  FIG. 1 ;  
       FIG. 3  is a partial bottom plan view of the power tool shown in  FIGS. 1 and 2 ;  
       FIG. 4  is a cross sectional view of a portion of the housing of the power tool shown in  FIG. 3  and the front end of the extension pole shown in  FIG. 2 ;  
       FIG. 5  is a block diagram showing two electrical paths in the power tool shown in  FIGS. 1-3 ;  
       FIG. 6  is a partial perspective view of an alternate embodiment of a movable connection system between the two pole members of the extension pole shown in  FIG. 1 ;  
       FIG. 7  is a partial perspective view of a tool assembly of an alternate embodiment of the present invention;  
       FIG. 8  is a rear end view of the chain saw tool shown in  FIG. 7  with the mounting bracket attached, but without showing the rest of the extension pole;  
       FIG. 9  is a cross sectional view one portion of the tool assembly shown in  FIG. 7 ;  
       FIG. 10  is an exploded perspective view of the portion of the tool assembly shown in  FIG. 9 ;  
       FIG. 11  is a cross sectional view taken along line  11 - 11  in  FIG. 9 ; and  
       FIG. 12  is a cross sectional view taken along line  12 - 12  in  FIG. 11 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIG. 1 , there is shown an elevational side view of a power tool assembly  10  incorporating features of the present invention. Although the present invention will be described with reference to the exemplary embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used.  
      The power tool assembly  10  generally comprises a power tool  12  and an extension pole  14 . In the embodiment shown, the power tool assembly  10  forms an extendable chain saw system. Specifically, the power tool  12  comprises an electric chain saw. However, in alternate embodiments, features of the present invention could be embodied in any suitable type of electric power tool, such as an electric hedge trimmer, for example. The extension pole  14  is an extendable extension pole. More specifically, the extension pole comprises telescoping pole members  16 ,  18  which can be slid relative to each other to lengthen or shorten the length of the extension pole  14 . However, in an alternate embodiment, the extension pole might not be an extendable extension pole and could have a fixed length.  
      The extension pole  14  generally comprises the two pole members  16 ,  18 , a rear end handle  20 , a hand grip section  22 , a rotatable friction collet  24 , a removable connection system  26 , and a front end having a limb hook  28 . The two pole members  16 ,  18  forms a pole section for the extension pole. The pole members  16 ,  18  are preferably comprised of fiberglass. In an alternate embodiment, the pole section could be comprised of more than two pole members, such as three or more pole members. The second pole member  18  is slidably connected to the first pole member  16  inside the first pole member  16 . The friction collet  24  is adapted to be rotated to stationarily fix the longitudinal position of the two pole members  16 ,  18  relative to each other. In an alternate embodiment, any suitable type of system for fixedly, but movably or adjustably locating the two pole members relative to each other could be provided.  
      The rear end handle  20  is fixedly attached to a rear end of the first pole member  16 . An electrical cord  30  extends out of the handle  20  and preferably comprises an electrical plug (not shown) to be connected to an electrical extension cord or an electrical outlet (not shown). In an alternate embodiment, the handle  20  could comprise an electrical connector adapted to receive a socket of an electrical extension cord. The handle  20  comprises an electrical switch  32 . The switch  32  comprises a user actuated trigger switch. The switch  32  is connected to the electrical cord  30  and an electrical cord  34  extending through the pole section.  
      The electrical cord  34  preferably comprises an extendable electrical cord, such as an electrical cord which is resiliently coiled inside the second pole member  18 . In the embodiment in which the extension pole is not extendable, the electrical cord  34  does not need to be expandable. The electrical cord  34  extends out of a front end of the second pole member  18  and comprises an electrical connector  36 . The electrical connector  36  is adapted to be removably connected to an electrical connector  38  at the rear end of the chain saw  12 . The extension pole  14  is adapted to supply electricity to the chain saw  12  based upon whether the trigger switch  32  is depressed by a user. The trigger switch  32  could comprise any suitable safety interlock to prevent inadvertent actuation.  
      Referring also to  FIGS. 2-4 , the removable connection system  26  generally comprises a rail  40  and a tightening knob  42  at the front end  44  of the extension pole. The front end  44  is connected to the front end of the second extension pole  18 . The rail  40  is located along a top side of the front end  44 . In the embodiment shown, the rail  40  has a general T shaped cross section. The tightening knob  42  comprises a knob section  46  and a shaft section  48 . The shaft section  48  extends through the front end  44 . The tightening knob  42  is located at a bottom side of the front end  44  and is fixedly attached to the shaft section  48 . The shaft section  48  is adapted to axially rotate. The shaft section  48  can slightly longitudinally move on the front end  44 , but is preferably not removable from the front end (i.e., the shaft section is movably captured on the front end). The top end of the shaft section  48  comprises a threaded section  50 . A user can rotate the knob section  46  as indicated by arrow  52  to rotate the threaded section  50  clockwise or counterclockwise.  
       FIG. 3  shows a partial bottom plan view of the chain saw  12 . As seen best in  FIGS. 1 and 2 , the chain saw  12  comprises a frame forming a housing  54 , an electric motor  56 , a chain bar  58  and a saw chain  60 . The electric motor  56  is located inside the housing  54 . A drive  68  is provided between the electric motor  56  and the saw chain  60  to drivingly rotate the saw chain  60  on the chain bar  58 . The housing  54  forms a rear end handle  62 . The electrical connector  38  is located at the rear end of the handle  62 . A portion  64  of the housing  54  extends beneath the handle  62  and connects the rear end of the handle to the rest of the housing.  
      The chain saw  12  comprises a user actuated trigger switch  66 . The trigger switch  66  is connected to the rear handle  62  at a front bottom side of the rear handle. The chain saw  12  can be operated without the extension pole  14 . More specifically, an extension cord can be plugged into the electrical connector  38  and a user can depress the trigger switch  66  to actuate the chain saw. The chain saw  12  comprises an interlock button  70  to prevent the trigger switch  66  from being inadvertently depressed.  
      As seen in  FIG. 3 , the bottom side of the housing  54  comprises an extension pole attachment system. The extension pole attachment system generally comprises a slot  72  and a hole  74  having a threaded fastener  76  located in the hole. The slot  72  is located in the bottom surface of the housing portion  64  located beneath the rear end handle  62 . As seen best in  FIG. 4 , the slot  72  comprises a general T shaped cross-section. The slot  72  is adapted to slidably received the rail  40  of the extension pole therein. The front end of the rail  40  can be slid into the rear end of the slot  72  as indicated by arrow  78 . The track slides generally parallel to a bottom surface of the bottom of the housing. When the rail  40  reaches the front end of the slot  72 , the shaft section  48  of the tightening knob  42  is located in registry with the hole  74  in the bottom side of the housing  54 . A user can rotate the tightening knob while pressing the shaft section  48  into the hole  74 . The threaded section  50  of the tightening knob can thread into the threaded fastener  76 . Further rotation of the tightening knob causes the tightening knob  42  and the threaded fastener  76  to clamp the front end  44  against the bottom side of the housing  54  and, in conjunction with the rail  40  in the slot  72 , fixedly and stationarily attach the front end  44  of the extension pole to the housing  54  of the chain saw  12 . The electrical connector  36  can then be plugged into the electrical connector  38 . One of the features of the present invention is the fact that the connection system provides a tool-less connection system. In other words, the connection system does not require the use of connection tools to connect and disconnect the power tool with the extension pole. This speeds up assembly and disassembly of the components. It also makes assembly and disassembly of the components easier than conventional types of systems.  
      In order to disassemble the extension pole from the chain saw, the user can merely reverse the process. The user can disconnect the electrical connector  36  from the electrical connector  38 , rotate the tightening knob  42  to disconnect the threaded section  50  from the threaded fastener  76 , and slide the front end  44  out of the slot  72  in a direction reverse to arrow  78 .  
      As seen in  FIG. 3 , in the embodiment shown the chain saw  12  comprises an electrical bypass switch  80 . The bypass switch  80  is separate and apart from the user actuated trigger switch  66 . The bypass switch  80  comprises an actuator lever  82 . The lever  82  extends into the slot  72 . When the rail  40  is inserted into the slot  72 , the rail  40  moves the lever  82  to thereby actuate the bypass switch  80 . In an alternate embodiment, the power tool could have an additional or optional bypass switch  81  which is adapted to be actuated when the knob  42  of the extension pole is attached to the power tool. The act of tightening the knob  42  can mechanically actuate the secondary, bypass switch mounted internally in the chainsaw. The present invention allows the chain saw to be actuated without requiring a bracket to be mounted to the rear handle of the chain saw, and does not require the primary user actuated trigger switch of the chain saw to be locked on.  
      Referring also to  FIG. 5 , the chain saw  12  comprises an electrical system comprising the motor  56 , the electrical connector  38 , the user actuated trigger switch  66 , and the bypass switch  80 . Electricity can be supplied from the electrical connector  38  to the motor  56  by two paths  82 ,  84 . The first path  82  is through the user actuated trigger switch  66 . The second path  84  is through the bypass switch  80 .  
      When the extension pole  14  is attached to the chain saw  12  and the bypass switch  80  is actuated by the rail  40  sliding into the slot  72 , a user does not need to depress the user actuated trigger switch  66  to actuate the chain saw  12 . Instead, in order to actuate the chain saw  12  a user needs to depress the user actuated trigger switch  32  at the rear end handle  20  of the extension pole  14 . The bypass switch  80  is automatically actuated when the extension pole  14  is properly connected to the chain saw  12 . Although the bypass switch  80  has been described above as comprising a lever which is moved by the rail  40 , in an alternate embodiment the bypass switch  80  could comprise any suitable type of switch, such as a Reed switch activated by a magnet  86  (see  FIG. 2 ) in the front end  44 . In alternate embodiments, any suitable type of automatic bypass switch could be provided. In another type of alternate embodiment, the bypass switch might not be automatic, but could be a manual switch. One of the features of the present invention is the fact that the user actuated trigger switch  66  does not need to be moved or depressed by the extension pole  14 . This allows for a connection system between the extension pole and the power tool which is easier and faster to connect and disconnect than conventional types of known systems.  
      Another feature of the present invention is the provision of the limb hook  28  on the front end  44  of the extension pole  14 . When the extension pole is attached to the chain saw  12 , the limb hook  28  is located beneath the chain saw, and is preferably behind the open saw chain  60 . The limb hook  28  allows the front end  44  to be hooked onto a limb of a tree to temporarily rest of the assembly  10  on the tree limb. Location of the limb hook  28  beneath the chain saw and behind the open portion of the saw chain allows for easier positioning of the limb hook onto a tree limb and, easier removal of the limb hook from the tree limb with quicker initiation of cutting once the limb hook is moved off of the tree limb. In an alternate embodiment, the limb hook  28  might not be provided.  
      Referring now also to  FIG. 6 , an alternate embodiment of the coupling between the first and second pole members is shown. In this embodiment, the coupling  88  comprises a bracket  90  and a tightening knob  92 . The front end of the first pole member  16  comprises a slot  94 . The bracket  90  is located around the front end of the first pole member  16  and comprises two flanges  96 ,  98  which are located opposite each other. The tightening knob  92  is adapted to clamp the flanges  96 ,  98  against each other to thereby tighten the bracket  90  on the front end of the first pole member  16 . As the bracket  90  is tightened onto the first pole member  16 , the front end of the first pole member  16  is compressed onto the second pole member  18  with the slot  94  being reduced. This forms a friction grip between the front end of the first pole member  16  and the second pole member  18 . The tightening knob  92  can be loosened to allow the second pole member  18  to longitudinally slide relative to the first pole member  16 . As noted above, in alternate embodiments, any suitable type of movable, but stationarily fixable connection system between the pole members could be provided.  
      In an alternate embodiment, the front end of the extension pole could comprise multiple projections adapted to be received into multiple slots in the power tool housing, similar to a multiple scabbard attachment system. In one type of alternate embodiment of the present invention, the front end of the extension pole could comprise a longitudinal slot or slots, and the housing or frame of the power tool could comprise one or more projections or rails adapted to extend into the slot(s) to attach the extension pole to the power tool.  
      Referring now to  FIGS. 7-12  an alternate embodiment of the present invention is shown. The tool assembly  100  generally comprises a power tool  102  and an extension pole  104 . The power tool  102  comprises an electric chain saw. The extension pole  104  generally comprises the two pole members  106 ,  108 , a rear end handle  120 , a friction clamp  124 , a removable connection system  126 , and a front end having a limb hook  128 . The two pole members  106 ,  108  forms a pole section for the extension pole. The pole members  106 ,  108  are preferably comprised of fiberglass. In an alternate embodiment, the pole section could be comprised of more or less than two pole members, such as three or more pole members. The second pole member  108  is slidably connected to the first pole member  106  inside the first pole member  106 . The friction clamp  124  is adapted to stationarily fix the longitudinal position of the two pole members  106 ,  108  relative to each other. In an alternate embodiment, any suitable type of system for fixedly, but movably or adjustably locating the two pole members relative to each other could be provided.  
      The rear end handle  120  is fixedly attached to a rear end of the first pole member  106 . An electrical cord  130  extends out of the handle  120  and preferably comprises an electrical plug (not shown) to be connected to an electrical extension cord or an electrical outlet (not shown). In an alternate embodiment, the handle  120  could comprise an electrical connector adapted to receive a socket of an electrical extension cord. The handle  120  comprises an electrical switch  132 . The switch  132  comprises a user actuated trigger switch. The switch  132  is connected to the electrical cord  130  and an electrical cord  134  extending through the pole section.  
      The electrical cord  134  preferably comprises an extendable electrical cord, such as an electrical cord which is resiliently coiled inside the second pole member  108 . In the embodiment in which the extension pole is not extendable, the electrical cord  134  does not need to be expandable. The electrical cord  134  extends out of a front end of the second pole member  108  and comprises an electrical connector (not shown). The electrical connector is adapted to be removably connected to an electrical connector  138  at the rear end of the chain saw  102 . The extension pole  104  is adapted to supply electricity to the chain saw  102  based upon whether the trigger switch  132  is depressed by a user. The trigger switch  132  could comprise any suitable safety interlock to prevent inadvertent actuation.  
      As seen best in  FIGS. 8-10 , the removable connection system  126  generally comprises a mounting bracket  144  having rails  140  and a two tightening knobs  142  at the front end of the extension pole. The mounting bracket  144  is connected to the front end of the second extension pole  108  at a lateral side tube section  145 . The tube section  145  is preferably aligned with the right/left center of gravity of the chain saw  102 . Thus, no gravitational twisting torque is exerted on the pole.  
      The rails  140  are located along sides of the mounting bracket  144  and project inward towards each other and form a receiving area  147  (see  FIG. 10 ) therebetween. As seen in  FIG. 9 , the tightening knobs  142  each comprise a knob section  146  and a shaft section  148 . The shaft section  148  extends through the mounting bracket  144 . The knob section  146  is located at a bottom side of the mounting bracket  144  and is fixedly attached to the shaft section  148 . The shaft section  148  is adapted to axially rotate. The shaft section  148  can slightly longitudinally move on the mounting bracket  144 , but is preferably not removable from the front end (i.e., the shaft section is movably captured on the front end) such as by the use of lock washers  178 . The top end of the shaft section  148  comprises a threaded section  150 . A user can rotate the knob section  146  to rotate the threaded section  150  clockwise or counterclockwise.  
      As seen best in  FIG. 10 , the chain saw  102  comprises a frame forming a housing  154 , an electric motor  156 , a chain bar  158  and a saw chain  160 . The electric motor  156  is located inside the housing  154 . A drive  168  is provided between the electric motor  156  and the saw chain  160  to drivingly rotate the saw chain  160  on the chain bar  158 . The housing  154  forms a rear end handle  162 . The electrical connector  138  is located at the rear end of the handle  162 . A portion  164  of the housing  154  extends beneath the handle  162  and connects the rear end of the handle to the rest of the housing.  
      As seen in  FIGS. 9 and 10 , the chain saw  102  comprises a user actuated trigger switch  166 . The trigger switch  166  is connected to the rear handle  162  at a front bottom side of the rear handle. The chain saw  102  can be operated without the extension pole  104 . More specifically, an extension cord can be plugged into the electrical connector  138  and a user can depress the trigger of the trigger switch  166  to actuate the chain saw. The chain saw  102  comprises an interlock button  170  (see  FIGS. 7 and 9 ) to prevent the trigger switch  166  from being inadvertently depressed.  
      The bottom side of the housing  154  comprises an extension pole attachment system. The extension pole attachment system generally comprises two slots  172  and a two holes  174  having threaded fasteners  176  located in or behind the holes. The slots  172  are located in the lateral sides of the bottom of the housing portion  164  located beneath the rear end handle  162 . The slots  172  are adapted to slidably received the rails  140  of the extension pole therein. The front end of the rails  140  can be slid into the rear end of the slots  172 .  
      The rails slide generally parallel to a bottom surface of the bottom of the housing. When the rails  140  reach the front end of the slots  172 , the shaft sections  148  of the tightening knobs  142  are located in registry with the holes  174  in the bottom side of the housing  154 . A user can rotate the tightening knobs while pressing the shaft sections  148  into the holes  174 . The threaded sections  150  of the tightening knobs can thread into the threaded fasteners  176 . Further rotation of the tightening knobs causes the tightening knobs  142  and the threaded fasteners  176  to clamp the mounting bracket  144  against the bottom side of the housing  154  and, in conjunction with the rails  140  in the slots  172 , fixedly and stationarily attach the mounting bracket  144  of the extension pole to the housing  154  of the chain saw  102 . The electrical connector (not shown) of the extension pole can be plugged into the electrical connector  138 .  
      In order to disassemble the extension pole from the chain saw, the user can merely reverse the process. The user can disconnect the pole&#39;s electrical connector from the electrical connector  138 , rotate the tightening knobs  142  to disconnect the threaded sections  150  from the threaded fasteners  176 , and slide the mounting bracket  144  out of the slots  172 .  
      As seem in  FIGS. 9-10 , the chain saw  102  comprises an electrical bypass system which comprises an electrical bypass switch  180 . The chain saw  102  comprises an electrical system comprising the motor  156 , the electrical connector  138 , the user actuated trigger switch  166 , and the bypass switch  180 . Electricity can be supplied from the electrical connector  138  to the motor  156  by two paths. The first path is through the user actuated trigger switch  166 . The second path is through the bypass switch  180 . The bypass switch  180  is separate and apart from the user actuated trigger switch  166 . The bypass switch  180  comprises an actuator button  182 . The bypass switch  180  can be actuated by slide block  184 . The slide block  184  is slidably mounted in the housing  154 . The slide block  184  has a front end with a cam surface  186  and a rear end with a button contact surface  188 . The slide block  184  is biased by a spring  190  towards a forward position.  
      The front knob  142  has an extension  192  at the end of its shaft section. When the front knob  142  is screwed into the front fastener  176 , the extension  192  is adapted to contact the cam surface  186  and cam the slide block  184  rearward. This causes the button contact surface  188  to actuate the bypass switch  180 . Thus, the act of tightening the front knob  142  can mechanically actuate the bypass switch. The present invention does not require the primary user actuated trigger switch  166  of the chain saw to be locked ON. When the front knob is unscrewed, the spring  190  can return the slide block  184  to its forward position and the bypass switch  180  becomes deactivated.  
      When the extension pole  104  is attached to the chain saw  102  and the bypass switch  180  is actuated by the slide block  184  moved by the front knob, a user does not need to depress the user actuated trigger switch  166  to actuate the chain saw  102 . Instead, in order to actuate the chain saw  102  a user needs to depress the user actuated trigger switch  132  at the rear end handle  120  of the extension pole  104 . The bypass switch  180  is automatically actuated when the extension pole  104  is properly connected to the chain saw  102 .  
      Although the bypass switch  180  has been described above as comprising a plunger moved by a cam which is moved by the fastener, in an alternate embodiment the bypass switch  180  could comprise any suitable type of switch. In alternate embodiments, any suitable type of automatic bypass switch could be provided. In another type of alternate embodiment, the bypass switch might not be automatic, but could be a manual switch. One of the features of the present invention is the fact that the user actuated trigger switch  166  does not need to be moved or depressed by the extension pole  104 . This allows for a connection system between the extension pole and the power tool which is easier and faster to connect and disconnect than conventional types of known systems.  
      In the embodiment shown, the chain saw  102  comprises a cover to cover the front hole  174  and prevent debris from clogging access to, or actuating movement of, the slide block  184 . As seen best in  FIGS. 9, 11  and  12 , the cover comprises a plate  194  and a spring  196 . The plate  194  is slidably mounted to the housing  154  between a forward position and a rearward position. The spring  196  biases the plate  194  is a rearward position. The plate  194  has side projections  198  which are adapted to be contacted by front recessed ledges  200  of the rails  140  when the mounting bracket  144  is slide forward on the housing. The mounting bracket  144  is, thus, able to move the plate  194  from its rearward position to its forward position. When the mounting bracket  144  is removed, the spring  196  is able to return the plate  194  back to its rearward position.  
      The plate  194  has a front section  202  with a hole  204 . When the plate  194  is in its forward position, the hole  204  is aligned with the front hole  174 . Thus, the shaft section of the front knob passes through the hole  204  into the front fastener  176 . When the plate  194  is in its rearward position, such as when the bracket  144  is not mounted to the chain saw  102 , the plate&#39;s hole  204  is not in alignment with the front hole  174 . Thus, the front section  202  of the plate  194  closes access to the front fastener  176  and the slide block  184  from the front hole  174 .  
      It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.