Patent Publication Number: US-8528217-B2

Title: Electric tool and remote control holder for the electric tool

Description:
TECHNICAL FIELD 
     The present invention relates to a rechargeable electric tool, such as a chain saw, in which an electric power source is supplied from a battery pack, and also to a remote control holder for holding the electric tool such that an operator can manipulate the electric tool remotely from his hand. 
     BACKGROUND ART 
     The applicant of this invention has proposed an invention disclosed in Patent Document 1 with respect to the aforementioned remote control holder (hereinafter simply referred to as a “holder”). This holder includes a connecting member connectable to an electric tool from which a battery pack has been removed, a switch restriction means provided on the connecting member and capable of retaining a switch of the electric tool in an ON state, a handle connected to the connecting member through a pipe and to which the battery pack is detachably mounted, a connecting means electrically connecting the electric tool and the battery pack mounted to the handle, and a switching means provided on the handle and configured to control an electric connection between the battery pack and the electric tool. 
     According to this holder, the connection between the electric tool and the connecting member is made only by utilizing an attachment structure between the electric tool and the battery pack. To be more specific, the connecting member has an insertion portion equipped with electrode terminal plates at the same positions as those of the battery pack, and at both sides of the insertion portion are provided hook buttons identical to those provided on the battery pack, so that when the insertion portion is inserted into an attachment portion of the electric tool, which is also used for insertion of the battery pack, the hook buttons can be engaged with and connected to corresponding recessed portions, etc. formed in the attachment portion of the electric tool. 
     As a connecting mechanism for connecting the electric tool and the battery pack, a slide connecting mechanism is also known, other than the hook buttons; the slide connecting mechanism includes a pair of guide rails provided on the attachment portion of the electric tool, a pair of slide rails provided on an upper surface of the battery pack and configured to be fitted inside and between the pair of guide rails by inserting the battery pack into a space between the pair of guide rails while sliding the slide rails relative to the guide rails, and a hook button provided on the battery pack and configured to be engageable with the attachment portion when the slide rails are snugly fitted into the corresponding guide rails. Further, electrode terminal plates are provided between the guide rails of the attachment portion in a manner parallel to the guide rails, and electrode terminals are disposed on the upper surface of the battery pack in the sliding direction so that when the battery pack is slid along the guide rails, the electrode terminal plates are held by the electrode terminals. 
     Therefore, when the slide connecting mechanism is used in the holder, slide rails and electrode terminals are respectively provided on upper surface of the connecting member.
     Patent Document 1: Japanese Laid-open Patent Publication No. 10-286786   

     DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
     However, if the above-mentioned connecting mechanism for connecting the electric tool and the battery pack is used for the holder, the weigh of the electric tool is applied to an interlocked portion, such as the recessed portions and the guide rails, during the use of the holder. As these recessed portions and the guide rails are originally designed to withstand only the weight of the battery pack, the interlocked portion subjected to repeated actions of attachment and detachment of the holder are worn out. As a result, backlash occurs at the connection area between the interlocked portion and the connecting member and is transmitted to the electrode terminals. Consequently, noise or vibration is generated in the case where the holder is connected and also in the case where the battery pack is connected. This may lead to uncomfortable feeling for a user, or poor contact which further results in reduced service life of the terminals. As an embodiment in which the connecting mechanism is not utilized as it is, Patent Document 1 discloses another structure in which the connecting member has an arm extending along the housing of the electric tool. However, such a structure disadvantageously involves complicated shape of the connecting member, which increases cost. 
     In view of the above, the present invention seeks to provide an electric tool and a holder, which are simple in structure without considerably increasing the cost, and which can maintain a better usability and a better electrical connection while burden on the attachment portion of the electric tool is restricted. 
     Means for Solving the Problems 
     In order to achieve the above object, the invention as disclosed in claim  1  is an electric tool comprising an attachment portion to which a battery pack is detachably mounted as an electric power source and an interlocked portion provided on the attachment portion that is configured to be used for connection with a remote control holder. The battery pack is attached to the attachment portion through sliding engagement such that a pair of slide rails provided on the battery pack is fitted inside and between a pair of guide rails provided on the attachment portion. The interlocked portion is arranged as a pair of ribs each provided on an outer surface of the attachment portion and protruding therefrom parallel to the pair of guide rails. 
     In order to achieve the above object, the invention as disclosed in claim  3  is a remote control holder for an electric tool of claim  1  comprising a connecting member connectable to the attachment portion of the electric tool. Additionally, a switch restriction device capable of retaining a switch of the electric tool is connected to the connecting member in an ON state, and a handle is connected to the connecting member through a pipe and is configured such that the battery pack is detachably mounted thereto. A connecting member is configured to electrically connect the electric tool attached to the connecting member with the battery pack mounted to the handle, and a switching member is provided on the handle and is capable of controlling an electric connection between the electric tool and the battery pack by means of the connecting member. Finally, the connecting member has an interlocking portion configured to engage with the pair of ribs for supporting the attachment portion, so that the connecting member is connectable to the attachment portion by the engagement between the ribs and the interlocking portion. 
     In this holder, it is preferable that the interlocking portion is arranged as a pair of wall members positioned outside the pair of guide rails and having opposed surfaces in which a pair of recessed grooves are formed for allowing the pair of ribs to be fitted into the recessed grooves. 
     Further, in order to achieve the above object, the invention as disclosed in claim  8  is an electric tool equipped with a remote control holder, wherein a connecting member of a remote control holder for an electric tool according to any one of claims  3  to  7  is connected to an electric tool according to claim  1  or  2 . 
     Effects of the Invention 
     According to the present invention, since the own weight of the electric tool is not applied to the guide rails provided on the attachment portion of the electric tool for detachably mounting the battery pack, it is possible to prevent the guide rails from being worn out. Therefore, when the holder or the battery pack is attached to the attachment portion of the electric tool, backlash does not occur. This can maintain a better usability and a better electrical connection. In particular, because of a simple structure including the pair of ribs additionally provided on the attachment portion for connection and the interlocking portion of the connecting member for the engagement with the ribs, a considerable increase in the cost can be avoided. 
     Further, the interlocked portion and the interlocking portion which maintain a conventional electric connection by means of a slide connecting mechanism can be simply provided, and the strength of the guide rails can be increased in the electric tool. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be described hereinafter with reference to the accompanying drawings. 
       FIG. 1  are perspective views of a chain saw as an example of a rechargeable electric tool, and a chain saw  1  has a conventional structure which includes a housing  2 , a guide bar  3  protruding from a front side of the housing  2 , a chain  4  looped around an outer periphery of the guide bar  3  in a tensioned state, and a drive mechanism, such as a motor (not shown), and a sprocket (not shown), which are built in the housing  2  for rotating the chain  4  along the guide bar  3 . A handle having a switch lever  6  is provided at an upper side of the housing  2 , and extending in a front-and-rear direction, and an attachment portion  7  to which a battery pack  11  as an electric power source is detachably mounted is arranged at a rear end of the handle  5 . The reference number  8  indicates a recess formed in a front-side inner surface of the handle  5  in the proximity of the switch lever  6 . The recess  8  is used for engagement with a switch rod  17  described later. 
     A pair of electrode terminal plates  9 ,  9  extending parallel to each other in an up-and-down direction are provided on the attachment portion  7 , and a pair of guide rails  10 ,  10  each having an L-shaped transverse section are provided outside the electrode terminal plates  9 ,  9 . The guide rails  10  protrude parallel to the electrode terminal plates  9 ,  9  such that end portions thereof face to each other. Although not shown in the figures, a pair of slide rails provided at an upper surface of the battery pack  11  is where the guide rails are fitted between the pair of guide rails  10 ,  10 , and a pair of electrode terminals which are electrically connected with the electrode terminal plates  9 ,  9  between the slide rails. To be more specific, when the slide rails of the battery pack  11  are fitted inside and between the pair of guide rails  10 ,  10  and slid along the guide rails  10 ,  10 , a hook button  12  provided on the battery pack  11  is brought into engagement with a locking hole  13  of the attachment portion  7 . Then, as seen in  FIG. 1(B) , the battery pack  11  is mounted to the attachment portion  7  and an electric connection is made. 
     A bolt attachment hole  14  used for connection with a holder  30  which will be described later is formed centrally in one end of the attachment portion  7  from which the battery pack  11  is inserted. The attachment hole  14  extends inward into the interior of the handle  5 . 
     Further, a pair of ribs  15 ,  15  as an interlocked portion used for connection with the holder protrudes from right and left outer surfaces of the attachment portion  7  that are outer sides of the guide rails  10 ,  10 . The ribs  15 ,  15  are parallel to the guide rails  10 ,  10  and have substantially the same length as that of the guide rails  10 ,  10 . Bolt attachment holes  16 ,  16  used for connection with the holder  30  are formed in one ends of the ribs  15 ,  15  opposite to the other ends from which the battery pack is inserted, in such positions that the attachment holes  16 ,  16  are coaxial with each other in a right-and-left direction orthogonal to the guide rails  10 ,  10 . 
     A switch rod  17  as a switch restriction device can be held bridging between the one end of one rib  15  near the attachment hole  16  and the recess  8  formed in the handle  5  of the chain saw  1 . As seen in  FIGS. 2 and 3 , the switch rod  17  has a distal end to be fitted into the recess  8 , and includes an extension portion  18  and a hook portion  19 . The extension portion  18  is an inverted L-shape and extends within a front-and-rear space surrounded by the handle  5 . The hook portion  19  extends from an end of the extension portion  18  while curving along an outer surface of the attachment portion  7  and has a distal end which can be engaged with the end of the rib  15 . Namely, in a state where the hook portion  19  is engaged with the end of the rib  15  with the distal end of the extension portion  18  being fitted into the recess  8 , the extension portion  18  depresses the switch lever  6  so that a switch (not shown) provided on the handle  5  is turned ON (see  FIG. 6 ). Further, the extension portion  18  has an insertion hole  20  into which one end of an L-shaped hexagonal wrench can be inserted, and an engagement strip  21  by which the other end of the hexagonal wrench can be held, so that the hexagonal wrench can be attached to the switch rod  17  along the extension portion  18 . 
     Next, a description will be given of a holder to which the chain saw  1  is connected. 
       FIG. 4  is a perspective view illustrating one example of the holder  30 . The holder  30  includes an elongated hollow pipe  31 , a connecting member  32  provided at one end of the pipe  31  and configured to connect the chain saw  1 , and a handle  33  provided at the other end of the pipe  31  and to which the battery pack  11  is mounted. 
     As seen in  FIGS. 5 to 8 , the connecting member  32  is a molded article made of synthetic resin and fixed to the distal end of the pipe  31  by screws. A connecting portion  34  for connecting the connecting member  32  to the chain saw  1  is provided at an upper surface of the connecting member  32  that is orthogonal to the pipe  31 . The connecting portion  34  includes a U-shaped connecting wall  35  as an interlocking portion protruding along an outer periphery of the connecting portion  34 , and a rectangular-shaped terminal connecting portion  36  protrusively provided inside the connecting wall  35 . A pair of parallel end portions  37 ,  37  of the connecting wall  35  are sized to cover the pair of guide rails  10 ,  10  of the chain saw  1  from outside, and have opposed surfaces in which a pair of recessed grooves  38 ,  38  are formed for allowing the pair of ribs  15  of the guide rails  10 ,  10  to be inserted from an open-side of the connecting wall  35 . 
     The reference number  39  indicates a through hole formed in each end portion  37  of the connecting wall  35  such that when the pair of ribs  15 ,  15  have been inserted into the corresponding recessed grooves  38 ,  38  into its connecting state, each of the attachment holes  16  of the ribs  15 ,  15  is aligned with the corresponding through hole  39 . A groove  40  is formed in the connecting portion  34  at an inner bottom portion of the end portion  37  corresponding to the rib  15  to which the switch rod  17  is attached. When the hook portion  19  of the switch rod  17  is fitted into the groove  40 , the hook portion  19  is allowed to be engaged with the rib  15 . 
     Further, the terminal connecting portion  36  has a pair of slits  41 ,  41  which extends from an upper surface of the terminal connecting portion  36  to an open-side surface of the connecting wall  35  in a manner parallel to each other and having the same distance as that of the pair of electrode terminal plates  9 ,  9  of the attachment portion  7 . An electrode terminal  42  is provided in each slit  41  so as to hold the inserted electrode terminal plate  9  and make an electric connection between them. 
     Meanwhile, the handle  33  consists of right and left halves which are made of synthetic resin using a split mold and symmetrical to each other. The handle  33  is formed by sandwiching the rear end of the pipe  31  between the right and left halves and fixing them by screws. As seen in  FIG. 9 , the handle  33  accommodates therein a switch  44  to which lead wires  43  extending from the electrode terminals  42  of the connecting member  32  and wired through the pipe  31  are connected, a switch lever  45  configured to depress a plunger of the switch  44  to turn ON the switch  44 , and a lock-off button  46  which is normally urged by a coil spring to a position where a depression of the switch lever  45  is inhibited but allows the depression of the switch lever  45  when the lock-off button  46  is depressed. 
     An attachment portion  47  for the battery pack  11  is arranged at a lower end of the handle  33 . Similar to the attachment portion  7  of the chain saw  1 , the attachment portion  47  includes a pair of guide rails  48 ,  48  (without ribs at their outer surfaces), a pair of electrode terminal plates  49 ,  49  positioned inside and between the guide rails  48 ,  48 , and a locking hole  50  with which the hook button  12  of the battery pack  11  is engaged. The electrode terminal plates  49 ,  49  are connected to the switch  44  through lead wires (not shown). 
     According to the chain saw  1  and the holder  30  configured as described above, the attachment portion  7  of the chain saw  1  from which the battery pack  11  has been removed and the connecting portion  34  of the connecting member  32  are coupled in such a manner that the pair of ribs  15 ,  15  of the guide rails  10 ,  10  are positioned to be fitted into the recessed grooves  38 ,  38  of the connecting wall  35 . Then the guide rails  10 ,  10  are slid along and between the end portions  37 ,  37  of the connecting wall  35  and the terminal connecting portion  36 . When the ends of the guide rails  10 ,  10  are brought into contact with inner base portions of the connecting wall  35 , the sliding movement of the guide rails  10 ,  10  is stopped. In this position, the electrode terminal plates  9 ,  9  of the attachment portion  7  enter the slits  41 ,  41  of the terminal connecting portion  36  so that an electric connection with respect to the electrode terminals  42 ,  42  can be made. 
     Thereafter, the switch rod  17  is attached in such a manner that the hook portion  19  is engaged with the rib  15  between the end portion  37  of the connecting wall  35  and the guide rail  10  while the distal end of the extension portion  18  is engaged with the recess  8  of the handle  5 . In this position of the switch rod  17 , a hexagon socket head cap bolt  22  is screwed into the attachment hole  14  and the attachment holes  16 ,  16 , respectively, from below and from right and left sides of the connecting member  32  by means of the hexagonal wrench. Accordingly, as seen in  FIGS. 6-8  and  10 , the chain saw  1  can be connected to the connecting member  32  through the connecting portion  34 . Since the weight of the chain saw  1  is applied to the ribs  15 ,  15  provided on the outer surfaces of the guide rails  10 ,  10  and the end portions  37 ,  37  of the connecting wall  35 , the guide rails  10 ,  10  are free from the load. 
     In this connecting state, the extension portion  18  of the switch rod  17  depresses the switch lever  6  so as to always maintain the ON state of the chain saw-side switch. It should be noted that the handle  5  of the chain saw  1  has a lock-off button  23  identical to that provided on the handle  33 , and upon connection, it is necessary to attach the switch rod  17  while the lock-off button  23  is being depressed. 
     In the case of the handle  33 , the slide rails of the battery pack  11  are fitted inside and between the pair of guide rails  48 ,  48  of the attachment portion  47  and then slid along the guide rails  48 ,  48  to thereby cause the hook button  12  to be brought into engagement with the locking hole  50 . This can cause the electrode terminal plates  49 ,  49  of the attachment portion  47  to be electrically connected with the electrode terminals on the battery pack  11 , and as seen in  FIGS. 9 and 10 , the battery pack  11  is assembled with the handle  33 . 
     According to the chain saw  1  and the holder  30  in the above embodiment, since the own weight of the chain saw  1  is not applied to the guide rails  10 ,  10  of the chain saw  1 , it is possible to prevent the guide rails  10 ,  10  from being worn out. Therefore, when the holder  1  or the battery pack  11  is attached, backlash does not occur. This can maintain a better usability and a better electrical connection. In particular, because of a simple structure including a pair of ribs  15 ,  15  provided on the guide rails  10 ,  10  and the connecting wall  35  of the connecting member  32  for retaining the ribs  15 ,  15 , a considerable increase in the cost can be avoided. 
     Further, the interlocked portion is arranged as a pair of ribs  15 ,  15  each provided on a corresponding outer surface of the pair of guide rails  10 ,  10  and protruding parallel to the pair of guide rails  10 ,  10 , to be connecting wall  35  positioned outside the pair of guide rails  10 ,  10  and having opposed surfaces in which a pair of recessed grooves  38 ,  38  are formed for allowing the pair of ribs  15 ,  15  to be fitted into the recessed grooves  38 ,  38 . Therefore, the interlocked portion and the interlocking portion which maintain a conventional electric connection by means of a slide connecting mechanism can be simply provided, and the strength of the guiderails  10 ,  10  can be increased. 
     In the above embodiment, a connection using the bolts is employed in addition to the engagement between the ribs and the connecting wall. However, the number of bolts and/or the connecting positions may be changed where appropriate. In the case where a locking mechanism such as a hook button is employed, the connection using the bolts may be omitted. 
     Further, the interlocked portion of the electric tool and the interlocking portion of the holder are not limited to those disclosed in the above embodiment, and various design changes may be made where appropriate. For example, a plurality of ribs and recessed grooves may be formed on each of the right and left sides, a plurality of projections may be arranged in line in place of the rib, and the connecting wall may be divided into a pair of right and left walls in place of a U-shaped wall. 
     Further, in the above embodiment, the present invention has been applied to a structure in which the electric tool and the battery pack are slidably coupled. However, the present invention may be applicable to a conventional structure as described in the background art, in which a hook button is brought into engagement with the attachment portion by inserting an insertion portion of the battery pack into the attachment portion. To be more specific, while an additional interlocked portion (recess, etc.) is formed in an outer surface of the attachment portion other than the interlocked portion for the hook button, the connecting member has a connecting wall or the like that is positioned outside the attachment portion and provided with an interlocking portion (hook portion, etc.) engageable with the interlocked portion. This can also provide a connection without utilizing the interlocked portion for the battery pack. 
     On the contrary, the switch restriction device is not limited to the switch rod disclosed in the above embodiment, and in accordance with the position, etc. of the switch lever, the configuration of the switch rod and/or the engagement position, etc. of the switch rod with respect to the electric tool may be modified where appropriate. However, as described in the above embodiment, if the switch rod is configured to be engageable with the end portion of the rib, and in addition to the connection of the connecting member, to be interposed and fixed by sandwiching between the attachment portion and the connecting wall, the attachment of the switch rod can be advantageously performed without any difficulty. 
     Other than those described above, various design changes may be made on the handle of the holder; for example, the lock-off button may not be provided, an auxiliary handle may be provided in a continuous manner, and the pipe may be a telescopically expandable member. Further, the electric tool connected to the holder is not limited to a chain saw, and other types of tools such as pruning shears, reciprocating saws, hedge trimmers, circular saws (for pruning), and grass shears may be used. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  are perspective views of a chain saw, in which (A) shows a state in which a battery pack is removed, and (B) shows a state in which the battery pack is mounted. 
       FIG. 2  are explanatory views of a switch rod, in which an upper view is a perspective view as viewed from above, and a lower view is a perspective view as viewed from below. 
       FIG. 3  are explanatory views of the switch rod, respectively showing a back view, a top view, a front view, and a bottom view from the upper-side of the drawing, and a right side view at the right-hand side of the drawing. 
       FIG. 4  is a perspective view of a holder, illustrating a state in which the battery pack is mounted. 
       FIG. 5  is an explanatory view illustrating an attachment portion of the chain saw and a connecting member of the holder. 
       FIG. 6  is a partial cross section illustrating a state in which the chain saw is connected to the connecting member of the holder. 
       FIG. 7  is a sectional view taken along the line A-A. 
       FIG. 8(A)  is a sectional view taken along the line B-B, and  FIG. 8(B)  is a sectional view taken along the line C-C. 
       FIG. 9  is a partial cross section illustrating a state in which the battery pack is mounted to a handle of the holder. 
       FIG. 10  is an explanatory view of the chain saw to which the holder is connected. 
     EXPLANATION OF REFERENCE NUMERALS 
       1 —CHAIN SAW,  2 —HOUSING,  5 —HANDLE,  6 —SWITCH LEVER,  7 —ATTACHMENT PORTION,  8 —RECESS,  9 —ELECTRODE TERMINAL PLATE,  10 —GUIDE RAIL,  11 —BATTERY PACK,  15 —RIB,  17 —SWITCH ROD,  18 —EXTENSION PORTION,  19 —HOOK PORTION,  30 —HOLDER,  31 —PIPE,  32 —CONNECTING MEMBER,  33 —HANDLE,  34 —CONNECTING PORTION,  35 —CONNECTING WALL,  36 —TERMINAL CONNECTING PORTION,  37 —END PORTION,  38 —RECESSED GROOVE,  42 —ELECTRODE TERMINAL,  44 —SWITCH,  45 —SWITCH LEVER,  47 —ATTACHMENT PORTION,  48 —GUIDE RAIL,  49 —ELECTRODE TERMINAL PLATE