Abstract:
The present invention provides a rechargeable electric tool in which a battery pack detachably mounted to a mounting part, which is formed lower than an opening provided at a housing, wherein a seal member is held in the housing to seal between the opening and the battery pack mounted to the mounting part. A projection projecting toward the opening side is provided at the seal member, and a passing hole that penetrates the projection and the seal member and allows a lead line connecting an electric component accommodated on the opening side in the housing to the battery pack to pass therethrough is formed.

Description:
BACKGROUND OF THE INVENTION 
     This application claims the entire benefit of Japanese Patent Application Number 2010-217589 filed on Sep. 28, 2010 and Japanese Patent Application Number 2011-002143 filed on Jan. 7, 2011, the entirety of which is incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a rechargeable electric tool in which a battery pack serving as an electric power source is detachably mounted to a mounting part formed lower than openings provided at a housing. 
     BACKGROUND ART 
     For example, Japanese Patent Application Laid-Open Publication No. 2009-78322 discloses a rechargeable electric tool in which a battery pack is detachably mounted to a battery mounting part a grip part. The grip part is continuously provided at a housing in which a motor, a driving mechanism, and the like are mounted. 
     In general, a hole is provided at a housing to expose a trigger of a switch necessary for electrical operations or/and a ventilation hole is provided at the housing to cool a motor in such rechargeable electric tool. 
     However, for example, in the case where such rechargeable electric tool is left outside during rain, the rainwater or the like occasionally enters the housing from an opening such as the hole or the ventilation hole. In such a case, the rainwater or the like having entered the housing passes through the grip part or the battery mounting part, and then enters a gap between the battery mounting part and the battery pack. Thus, the waterproof property of the battery mounting part and the battery pack has been insufficient. 
     The present invention has been proposed in view of the foregoing circumstances, and an object thereof is to provide a rechargeable electric tool in which the waterproof property of the battery mounting part and the battery pack is improved. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention, a rechargeable electric tool including a housing having openings, a mounting part that is located lower than the openings and is formed at the housing, a battery pack detachably mounted to the mounting part to serve as an electric power source, and a seal member disposed in the housing to seal between the openings and the battery pack mounted to the mounting part. 
     According to a second aspect of the present invention, an electric component is accommodated in the opening side of the housing in which openings are provided, and the seal member includes a covering member that closely covers a lead line connecting the electric component to the battery pack and penetrating the seal member, and elastic members that are pressed into and brought into contact with the covering member in the first aspect of the present invention. 
     According to a third aspect of the present invention, a projection projecting toward the opening side at the seal member, and a passing hole that penetrates the projection and the seal member and allows the lead line connecting the electric component accommodated on the opening side in the housing to the battery pack to pass therethrough is formed in the first aspect of the present invention. 
     According to a fourth aspect of the present invention, the housing is formed by combining two divided housings with each other. Ribs capable of pressing the seal member may protrude from inner surfaces of the two divided housings while facing each other. The ribs hold the seal member in the housing in a state where the two divided housings are combined with each other in any one of the first to third aspects of the present invention. 
     According to a fifth aspect of the present invention, the electric component is accommodated on the opening side in the housing, and the seal member is held in the housing in a state where the seal member is twisted around an outer circumferential surface of the electric component in the first aspect of the present invention. 
     According to a sixth aspect of the present invention, the seal member is held in the housing in a state where the seal member is inclined relative to a bottom surface of the battery pack mounted to the mounting part. A drainage port which communicates inside of the housing to outside thereof is provided near an inclined lower end of the seal member on the opening side in the housing in the first aspect of the present invention. 
     According to a seventh aspect of the present invention, the electric component is a switch that includes an operation part to control supplying of electric power to a motor that drives an output shaft protruding from a tip end of the housing. The operation part is allowed to be exposed from the opening. The seal member is held in the housing in a state where the seal member is inclined relative to the bottom surface of the battery pack mounted to the mounting part and the inclined lower end is directed toward the opening in the fifth aspect of the present invention. 
     According to the rechargeable electric tool in the first aspect of the present invention, even if rainwater or the like enters inside of the housing from the openings of the housing, the seal member can prevent the rainwater or the like from entering a gap between the mounting part and the battery pack, and the battery pack. Accordingly, it is possible to improve the waterproof property of the gap and the battery pack. 
     According to the second aspect of the present invention, the covering member is closely attached to the lead line to cover it. As a result, there is no gap between the covering member and the lead line. Therefore, the rainwater or the like having entered inside of the housing from the openings can be prevented from flowing toward the battery pack along the lead line. 
     In addition, the elastic members are pressed into and brought into contact with the covering member to seal the surfaces of the covering member facing the elastic members. Accordingly, there is no gap between the covering member and the elastic members, and the rainwater or the like can be prevented from flowing toward the battery pack along the covering member. 
     According to the third aspect of the present invention, even if the rainwater or the like having entered inside of the housing from the openings passes between an inner surface of the housing and the electric component and flows toward the seal member, the projection of the seal member can prevent the rainwater or the like from flowing back to the opening side, and the rainwater or the like can be prevented from flowing toward the passing hole. Accordingly, the rainwater or the like can be prevented from flowing toward a gap between the mounting part for the battery pack and the battery pack, and the battery pack along the lead line passing through the passing hole. 
     According to the fourth aspect of the present invention, the seal member is not shaken by being pressed between the both ribs, and the seal member can be prevented from being moved in the housing. Accordingly, the seal member can be preferably positioned in the housing. 
     According to the fifth aspect of the present invention, the electric component around the outer circumferential surface of which the seal member is twisted is only combined with and accommodated in the housing, so that the seal member can be positioned in the housing. Accordingly, the seal member can be easily positioned. 
     According to the sixth aspect of the present invention, even if the rainwater or the like having entered the inside of the housing from the openings passes through the housing and flows toward the seal member, the rainwater or the like having reached the seal member can be guided to the drainage port along the inclination of the seal member. Accordingly, the rainwater or the like is discharged to the outside of the housing, and can be prevented from entering the gap and the battery pack. 
     According to the seventh aspect of the present invention, the rainwater or the like is discharged from the openings to the outside of the housing by using the openings without additionally providing the drainage port in the housing. As a result, the rainwater or the like can be prevented from entering a gap between the mounting part for the battery pack and the battery pack, and the battery pack. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, other advantages and further features of the present invention will become more apparent by describing in detail illustrative, non-limiting embodiments thereof with reference to the accompanying drawings. 
         FIG. 1  is a lateral cross-sectional view of main parts of an impact driver according to a first embodiment of the present invention. 
         FIG. 2  is a rear cross-sectional view of the main parts of the impact driver according to the first embodiment of the present invention. 
         FIG. 3  is an exploded perspective view of left and right half housings and a seal member forming the impact driver according to the first embodiment of the present invention. 
         FIG. 4  is a lateral cross-sectional view of main parts of an impact driver according to a second embodiment of the present invention. 
         FIG. 5  is a cross-sectional view taken along the line A-A of  FIG. 4 . 
         FIG. 6  is a cross-sectional view taken along the line B-B of  FIG. 4 . 
         FIG. 7  is a lateral cross-sectional view of main parts of an impact driver according to a third embodiment of the present invention. 
         FIG. 8  is a cross-sectional view taken along the line C-C of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     An Illustrative embodiment of the present invention will be described in detail with reference to the drawings. 
     First Embodiment 
     A first embodiment of the present invention will be described with reference to  FIG. 1  to  FIG. 3 . As shown in  FIG. 1 , an impact driver  1  includes a main-body housing  10 , a hammer case  20 , a seal member  50 , and the like. 
     As shown in  FIG. 1  and  FIG. 2 , a main-body housing  10  is formed by combination of left and right half housings  10 L and  10 R made of resin, and includes a body  11 , a handle part  12 , a battery mounting part  13 , and rear cover R. The body  11  is in a tubular shape and extends in the impact driver  1  in the vertical direction of  FIG. 1 . Inside of the body  11 , a motor M is accommodated, and plural inlet ports  14 A and outlet ports  14 B (see  FIG. 3 ) are provided at positions near the motor M. Further, the rear cover R formed in a tubular shape that is opened toward the body  11  is attached to a rear end of the body  11  by screwing. Plural inlet ports R 1  (see  FIG. 3 ) are provided even at the rear cover R, and these inlet ports  14 A and R 1  are used to draw in cooling air for the motor M in the body  11 . The plural outlet ports  14 B are used to discharge the cooling air to the outside of the body  11 . It should be noted that the main-body housing  10  is an example of a housing of the present invention, the both half housings  10 L and  10 R are examples of two half housings of the present invention, and the inlet ports  14 A and R 1  are examples of openings of the present invention. 
     As shown in  FIG. 1  to  FIG. 3 , the handle part  12  is formed by combining a left handle part  12 L of the left-half housing  10 L with a right handle part  12 R of the right-half housing  10 R. The handle part  12  extends from the body  11  so as to form a substantially T-shape when viewed from the lateral side of the impact driver  1 . Inside of the handle part  12 , a box-like switch S having a trigger  15  is accommodated at an upper position relative to the seal member  50  in the vertical direction of the impact driver  1 . In addition, the handle part  12  is provided with a drainage port  17  at the base of the handle part  12 , namely, at a position near a boundary between the handle part  12  and the battery mounting part  13 . The drainage port  17  can be communicated inside of the handle part  12  with the outside thereof. The position where the switch S is accommodated and the position where the drainage port  17  is provided in the handle part  12  correspond to the side where the inlet ports  14 A and R 1  are located with the seal member  50  serving as a boundary. It should be noted that the positions inside of the handle part  12  corresponding to the side where the inlet ports  14 A and R 1  are located are examples in the housing on the opening side of the present invention. 
     As shown in  FIG. 2  and  FIG. 3 , a rib  18 L protrudes from an inner surface of the left handle part  12 L, and a rib  18 R protrudes from an inner surface of the right handle part  12 R. Each of the both ribs  18 L and  18 R is formed in a moderate S-shape in accordance with the lateral shape of the seal member  50 . In a state where the left and right half housings  10 L and  10 R are combined with each other, the rib  18 L faces the rib  18 R in the handle part  12  in the vertical direction of  FIG. 2 . A cylindrical protrusion  19 A protrudes from the rib  18 R. The protrusion  19 A is provided so as to face a position near a front end of an upper curved part  50 A of the S-shape of the seal member  50  on a surface of the rib  18 R facing the seal member  50 . In addition, a cylindrical protrusion  19 B protrudes from the rib  18 R. The protrusion  19 B is provided so as to face a position near a rear end of a lower curved part  50 B of the S-shape of the seal member  50  on a surface of the rib  18 R facing the seal member  50 . 
     The battery mounting part  13  is formed by combining a left battery mounting part  13 L of the left-half housing  10 L with a right battery mounting part  13 R of the right-half housing  10 R. This battery mounting part  13  is formed on the lower side relative to the inlet ports  14 A and R 1  in the vertical direction of the impact driver  1 , namely, at a lower end of the handle part  12 . A terminal stage is accommodated in the battery mounting part  13 , and a battery pack  16  formed in a substantially rectangular solid shape is detachably mounted to the terminal stage. The battery pack  16  is a rechargeable electric power source. The trigger  15  is pushed into the inside of the handle part  12  to turn on the switch S, so that the battery pack  16  supplies electricity to the motor M. Further, a hook F (see  FIG. 2 ) used to hang the impact driver  1  on a belt of a worker is swingably attached to a left lateral surface of the battery mounting part  13  when viewed from the backside. It should be noted that the impact driver  1  is an example of a rechargeable electric tool of the present invention, and the battery mounting part  13  is an example of a mounting part of the present invention. In addition, the trigger  15  is an example of an operating part of the present invention. 
     The hammer case  20  is made of metal (for example, aluminum), and is combined with the front side (right direction of  FIG. 1 ) of the body  11 . Inside of the hammer case  20 , a hammering mechanism and an anvil  21  are accommodated. The anvil  21  is rotatably supported by a bearing in the hammer case  20 , and projects from a tip-end surface of the hammer case  20 . A chuck  22  is provided at a tip end of the anvil  21 , so that a tip-end tool can be mounted. The hammering mechanism converts the rotation of the motor M into rotational hammering force to be transmitted to the tip-end tool. It should be noted that the anvil  21  is an example of an output shaft of the present invention. 
     A cover  30  is mounted at a part exposed from the body  11  on the front outer circumference of the hammer case  20 . A bumper  40  is combined with a front end of the cover  30  and is mounted at the exposed part. The cover  30  and the bumper  40  prevent the front outer circumference of the hammer case  20  from being exposed. 
     The seal member  50  is arranged between the switch S and the battery pack  16  in the handle part  12 . In other words, the seal member  50  is located between the opening including inlet ports  14 A, R 1  and an opening H used for exposing the trigger  15  from the handle part  12 , and the battery pack  16 . Accordingly, the seal member  50  can seal between the side where the inlet ports  14 A, R 1  and the opening H are located and the side where the battery pack  16  is provided in the handle part  12 . The seal member  50  is made of elastic material such as rubber, has a thickness in the horizontal direction of the handle part  12 , and each of the lateral surfaces of the seal member  50  is formed in a moderate S-shape. 
     As shown in  FIG. 1  and  FIG. 3 , the seal member  50  is configured in such a manner that an upper surface of the upper curved part  50 A forming the S-shape serves as an inclined surface (upper inclined surface) S 1 . The inclined surface S 1  is inclined upward in the front direction relative to a bottom surface  16 A of the battery pack  16  mounted to the battery mounting part  13 . A projection  51  is formed at a front end of the upper inclined surface S 1 . The projection  51  projects upward (toward the side where the inlet ports  14 A and R 1  and the opening H are located) from the upper inclined surface S 1 . A lead-line passing hole  52  penetrating the projection  51  and the upper curved part  50 A is formed in the vertical direction of the seal member  50 . In addition, a through-hole  53 A is formed at a position on the upper-end side (a position on the front side) of the upper curved part  50 A in the projection  51 . The through-hole  53 A is formed in the thickness direction of the projection  51  (seal member  50 ), and the protrusion  19 A can be inserted into the through-hole  53 A. 
     On the other hand, an upper surface of the lower curved part  50 B forming the S-shape serves as an inclined surface (lower inclined surface) S 2 . The inclined surface S 2  is inclined downward in the rear direction relative to the bottom surface  16 A of the battery pack  16  mounted to the battery mounting part  13 . As shown in  FIG. 1 , the drainage port  17  is located near a lower end of the lower inclined surface S 2 . In addition, a through-hole  53 B is formed at a position on the rear side of the lower curved part  50 B. The through-hole  53 B is formed in the same direction as the through-hole  53 A, and the protrusion  19 B can be inserted into the through-hole  53 B. 
     In a state where the left and right half housings  10 L and  10 R are combined with each other as shown in  FIG. 2 , the protrusion  19 A is inserted into the through-hole  53 A, and the protrusion  19 B is inserted into the through-hole  53 B, so that the rib  18 L is pressed into a left lateral surface of the seal member  50 , and the rib  18 R is pressed into a right lateral surface of the seal member  50 . Accordingly, the left and right lateral surfaces of the seal member  50  are elastically deformed to be closely attached to the both ribs  18 L and  18 R, respectively. At the same time, the seal member  50  is sandwiched and held between the both ribs  18 L and  18 R in a state where the seal member  50  is fitted into the handle part  12 . In a state where the seal member  50  is held in the handle part  12 , the seal member  50  is inclined downward toward the rear side of the battery pack  16  relative to the bottom surface  16 A of the battery pack  16 . It is due to the presence of the upper inclined surface S 1  and the lower inclined surface S 2 . 
     As shown in  FIG. 1 , an internal connector C 1  is accommodated in the handle part  12  on the battery pack  16 -side. A lead line L connected to the internal connector C 1  is allowed to pass through the lead-line passing hole  52  to extend from the battery pack  16 -side to the side where the inlet ports  14 A and R 1  and the opening H are located in the handle part  12 . The lead line L is electrically connected to the switch S on the side where the inlet ports  14 A and R 1  and the opening H are located in the handle part  12 . A lead line (not shown) for supplying electricity to the motor M is electrically connected between the switch S and the motor M. In addition to the lead line L, a communication line (not shown) and the like are allowed to pass through the lead-line passing hole  52  without a gap. 
     An external connector C 2  is accommodated on the battery pack  16 -side in the handle part  12  in a state where the external connector C 2  is coupled to the internal connector C 1 . A lead line (not shown) connected to the external connector C 2  extends toward the lower end side (battery mounting part  13 ) of the handle part  12  to be electrically connected to the terminal stage. In the illustrated impact driver  1 , the switch S and the battery pack  16  are electrically connected to each other through the both connectors C 1  and C 2 , the lead line L, and the like. In the embodiment, non-waterproof connectors are used as the both connectors C 1  and C 2 . Accordingly, the both connectors C 1  and C 2  are small in size as compared to waterproof connectors. Therefore, the both connectors C 1  and C 2  can be accommodated in a narrow space in the handle part  12  surrounded by the seal member  50 , an inner surface of the handle part  12  on the battery pack  16 -side, and the battery mounting part  13 . It should be noted that the switch S is an example of an electric component of the present invention, and the lead-line passing hole  52  is an example of a passing hole of the present invention. 
     For example, even if the impact driver  1  of the embodiment is left outside in a standing posture while the bottom surface  16 A of the battery pack  16  is brought into contact with the ground, and rainwater or the like enters from the inlet ports  14 A and R 1  and the opening H (see  FIG. 1 ), the rainwater or the like can be prevented from entering the battery pack  16  and the like in the following manner. The rainwater or the like having entered from the inlet ports  14 A and R 1  flows down from the inside of the body  11 . It flows down toward the seal member  50  and the ribs  18 L and  18 R through a gap between an inner surface of the handle part  12  and the switch S. At this time, there is no gap between the side where the inlet ports  14 A and R 1  are located and the battery pack  16 -side in the handle part  12  due to the presence of the seal member  50 . Thus, the rainwater or the like can be prevented from entering the battery pack  16 -side from the side where the inlet ports  14 A and R 1  are located. 
     In addition, the rainwater or the like having reached the seal member  50  flows down on the upper inclined surface S 1  and the lower inclined surface S 2  to be guided to the drainage port  17 . Further, the rainwater or the like having reached the ribs  18 L and  18 R is guided to the drainage port  17  along upper surfaces of the ribs  18 L and  18 R. Thereafter, the rainwater or the like passes through the drainage port  17  from the inside of the handle part  12  to be discharged to the outside of the handle part  12 . In addition, the rainwater or the like having reached the seal member  50  hardly flows back to the side where the inlet ports  14 A and R 1  are located due to the upward inclination of the upper inclined surface S 1 , and the projection  51  serves as a barrier against backflow. Thus, the rainwater or the like is prevented from flowing into the lead-line passing hole  52 . Further, since the projection  51  projects upward relative to the upper surfaces of the ribs  18 L and  18 R, the rainwater or the like flowing on the upper surfaces of the ribs  18 L and  18 R is prevented from flowing into the lead-line passing hole  52  by the projection  51  serving as a barrier. Therefore, the rainwater or the like can be prevented from entering the battery pack  16 -side in the handle part  12  along the lead line L and the like allowed to pass through the lead-line passing hole  52 . Accordingly, the rainwater or the like is prevented from flowing into the internal connector C 1  and the external connector C 2  connected to the lead line L, and thus the waterproof property of the both connectors C 1  and C 2  is improved. 
     On the other hand, the rainwater or the like having entered from the opening H is also prevented from entering the battery pack  16 -side from the side where the inlet ports  14 A and R 1  and the opening H are located in the handle part  12 , as similar to that having entered from the inlet ports  14 A and R 1 . In addition, the rainwater or the like having entered from the opening H is guided to the drainage port  17 , as similar to that having entered from the inlet ports  14 A and R 1 . Thereafter, the rainwater or the like is discharged to the outside of the handle part  12 . In addition, the rainwater or the like having entered from the opening H is prevented from flowing into the lead-line passing hole  52 , as similar to that having entered from the inlet ports  14 A and R 1 . Accordingly, the rainwater or the like having entered from the opening H can be prevented from entering the battery pack  16 -side, as similar to that having entered from the inlet ports  14 A and R 1 . It should be noted that the opening H is an example of an opening of the present invention. 
     Effect of the First Embodiment 
     In the impact driver  1  of the first embodiment, the seal member  50  seals a portion in the handle part  12  between the inlet ports  14 A and R 1  and the opening H, and the battery pack  16  mounted to the battery mounting part  13  located lower in the vertical direction of the impact driver  1  than the inlet ports  14 A and R 1  and the opening H. Thus, even if the rainwater or the like flows down from the inlet ports  14 A and R 1  toward the handle part  12  through the body  11 , or the rainwater or the like enters from the opening H and flows down along an inner surface of the handle part  12 , the seal member  50  can prevent the rainwater or the like from entering a gap between the battery mounting part  13  and the battery pack  16 , and the battery pack  16 . Accordingly, it is possible to improve the waterproof property of the gap and the battery pack  16 . 
     Further, even if the rainwater or the like having entered from the inlet ports  14 A and R 1  flows down to the seal member  50  from the inside of the body  11  through a gap between an inner surface of the handle part  12  and the switch S, the projection  51  can prevent the rainwater or the like from flowing back to the side where the inlet ports  14 A and R 1  are located. As a result, the rainwater or the like can be prevented from flowing into the lead-line passing hole  52 . In addition, the rainwater or the like having entered from the opening H can be also prevented from flowing back to the side where the inlet ports  14 A and R 1  and the opening H are located by the projection  51 . As a result, the rainwater or the like can be prevented from flowing toward the lead-line passing hole  52 . Accordingly, the rainwater or the like can be prevented from entering the battery pack  16 -side along the lead line L and the like allowed to pass through the lead-line passing hole  52 . 
     Further, in a state where the left and right half housings  10 L and  10 R are combined with each other, the seal member  50  is held in the handle part  12  while being sandwiched between the both ribs  18 L and  18 R. Therefore, the seal member  50  is not shaken by being pressed between the both ribs  18 L and  18 R, and the seal member  50  can be prevented from being moved in the handle part  12 . Accordingly, the seal member  50  can be preferably positioned in the handle part  12 . 
     Furthermore, the drainage port  17  is provided at a position corresponding to the side where the inlet ports  14 A and R 1  and the opening H are located in the handle part  12 . The drainage port  17  is positioned near a lower end of the lower inclined surface S 2  of the seal member  50 . Therefore, even if the rainwater or the like having entered from the inlet ports  14 A and R 1  and the opening H flows down in the handle part  12 , the rainwater or the like having reached the seal member  50  flows down on the upper inclined surface S 1  and the lower inclined surface S 2  to be discharged from the drainage port  17  to the outside of the handle part  12 . Accordingly, the rainwater or the like having entered from the inlet ports  14 A and R 1  and the opening H can be prevented from entering the gap and the battery pack  16 . 
     Second Embodiment 
     A second embodiment of the present invention will be described with reference to  FIG. 4  to  FIG. 6 . In the second embodiment, the same constitutional elements as those in the first embodiment are given the same reference numerals and the explanations thereof will not be repeated. In addition, the same effects as those in the first embodiment will not be repeated. Further, the lead line L is not illustrated in  FIG. 4 . However, the lead line L same as that in the first embodiment is also provided in an impact driver  1 A of the second embodiment. The impact driver  1 A includes a heat-shrinkable tube  55 , single-bubble sponges  56  ( 56 A and  56 B), and a seal member  60 . An inner circumferential surface of the heat-shrinkable tube  55  is coated with an adhesive. The heat-shrinkable tube  55  is heated after being mounted to the lead line L and a communication line L 1 , so that the heat-shrinkable tube  55  is shrunk and closely attached to the lead line L and the like. Accordingly, as shown in  FIG. 5  and  FIG. 6 , the heat-shrinkable tube  55  covers the lead line L and the communication line L 1 . At the same time, the adhesive is melted to flow between the lead line L and the communication line L 1 . Then, the adhesive is hardened after cooling, so that the heat-shrinkable tube  55 , the lead line L and the communication line L 1  are tightly closed to each other. 
     The single-bubble sponge  56 A includes a concave groove  57  that extends in the vertical direction and is opened on the lateral side. A concave groove  61  extending in the vertical direction of the seal member  60  is formed at a projection  51  of the seal member  60 . The single-bubble sponge  56 A is fitted into the concave groove  61  in a state where tip-ends of the single-bubble sponge  56 A project from the concave groove  61  in the horizontal direction. A concave groove  58  that is opened toward an inner surface of the handle part  12 L is formed at a single-bubble sponge  56 B whose cross-section is U-shaped as shown in  FIG. 6 . The single-bubble sponge  56 B is formed in a substantially rectangular shape in planar view, and is fitted into the concave groove  57  from the proximal side of the single-bubble sponge  56 B. 
     Before combining the left and right half housings  10 L and  10 R with each other, the lead line L and the communication line L 1  covered with the heat-shrinkable tube  55  are allowed to pass through the concave groove  57  of the single-bubble sponge  56 A and to penetrate the seal member  60 , so that the switch S and the internal connector C 1  are electrically connected to each other. As shown in  FIG. 5  and  FIG. 6 , when the left and right half housings  10 L and  10 R are combined with each other, the rib  18 R is pressed into a right lateral surface of the seal member  60 . At the same time, the rib  18 L presses the single-bubble sponge  56 B into the heat-shrinkable tube  55  in a state where the rib  18 L is fitted into the concave groove  58  of the single-bubble sponge  56 B. At this time, the rib  18 L is closely attached to the single-bubble sponge  56 A while deforming the same. As a result, the single-bubble sponge  56 A and the single-bubble sponge  56 B are pressed into and brought into contact with an outer circumferential surface of the heat-shrinkable tube  55 , so that surfaces of the heat-shrinkable tube  55  facing the single-bubble sponge  56 A and the single-bubble sponge  56 B are sealed. It should be noted that the heat-shrinkable tube  55  is an example of a covering member of the present invention, and the single-bubble sponges  56 A and  56 B are examples of elastic members of the present invention. 
     In the second embodiment, even if rainwater or the like reaches the lead line L and the communication line L 1  through the inlet ports  14 A and R 1  and the opening H, the rainwater or the like can be prevented from entering the battery pack  16 -side in the following manner. Since there is no gap between the heat-shrinkable tube  55  and the lead line L and the communication line L 1 , the rainwater or the like flowing toward the heat-shrinkable tube  55  along the lead line L and the communication line L 1  neither passes between the heat-shrinkable tube  55  and the lead line L and the like, nor enters the battery pack  16 -side in the handle part  12 . Further, since the surfaces of the heat-shrinkable tube  55  facing the single-bubble sponge  56 A and the single-bubble sponge  56 B are sealed, there is no gap between the heat-shrinkable tube  55  and each of the single-bubble sponges  56 A and  56 B. Thus, the rainwater or the like flowing along the lead line L and the communication line L 1  neither passes between the heat-shrinkable tube  55  and each of the single-bubble sponges  56 A and  56 B, nor enters the battery pack  16 -side in the handle part  12 . 
     Effect of the Second Embodiment 
     In the impact driver  1 A of the second embodiment, the heat-shrinkable tube  55  is closely attached to the lead line L and the communication line L 1  to cover the lead line L and the like. As a result, there is no gap between the heat-shrinkable tube  55  and the lead line L and the like. Therefore, the rainwater or the like having entered from the inlet ports  14 A and R 1  and the opening H can be prevented from flowing toward a gap between the battery mounting part  13  and the battery pack  16 , and the battery pack  16  from between the heat-shrinkable tube  55  and the lead line L and the like. 
     In addition, the surfaces of the heat-shrinkable tube  55  facing the single-bubble sponge  56 A and the single-bubble sponge  56 B are sealed, so that there is no gap between the heat-shrinkable tube  55  and each of the single-bubble sponges  56 A and  56 B. Therefore, the rainwater or the like can be prevented from flowing toward the gap between the battery mounting part  13  and the battery pack  16  or toward the battery pack  16  from between the heat-shrinkable tube  55  and each of the single-bubble sponges  56 A and  56 B. 
     Third Embodiment 
     A third embodiment of the present invention will be described with reference to  FIG. 7  and  FIG. 8 . In the third embodiment, the same constitutional elements as those in the first and second embodiments are given the same reference numerals and the explanations thereof will not be repeated. Unlike the first and second embodiments, an impact driver  1 B of the third embodiment has a body  11 A formed in a tubular shape without providing the rear cover R. The impact driver  1 B is provided with a seal member  70 . The seal member  70  is made of elastic material such as rubber. As shown in  FIG. 7 , the seal member  70  is fitted into a position in the handle part  12  between the inlet port  14 A and the opening H, and the battery pack  16  in a state where the seal member  70  is twisted around an outer circumferential surface of the switch S. Accordingly, the seal member  70  seals between the side where the inlet port  14 A and the opening H are located and the battery pack  16 -side in the handle part  12 . The seal member  70  is twisted around the outer circumferential surface in a state where the seal member  70  is inclined downward toward the front side of the battery pack  16  relative to the bottom surface  16 A of the battery pack  16 . A rib guiding grove  71  is provided on the entire circumference of the seal member  70 . Further, as shown in  FIG. 8 , a thin-plate rib  18 L 1  protrudes across the entire inner circumference of the left handle part  12 L, and a thin-plate rib  18 R 1  protrudes across the entire inner circumference of the right handle part  12 R. The ribs  18 L 1  and  18 R 1  are arranged on a plane that is inclined downward in the front direction relative to the bottom surface  16 A. 
     When the left and right half housings  10 L and  10 R are combined with each other, the ribs  18 L 1  and  18 R 1  are engaged with the rib guiding groove  71  while the trigger  15  is exposed from the opening H in a state where the seal member  70  is twisted around the outer circumferential surface of the switch S, so that the switch S is accommodated in the handle part  12 . Accordingly, the seal member  70  is positioned and held in the handle part  12 . At this time, the seal member  70  is arranged in such a manner that its inclined lower end is directed toward the opening H. 
     In the third embodiment, even if rainwater or the like enters the inside of the handle part  12  through the inlet port  14 A and the opening H, the rainwater or the like can be prevented from entering the battery pack  16 -side in the following manner. Due to the presence of the seal member  70 , there is no gap between the side where the inlet port  14 A and the opening H are located and the battery pack  16 -side in the handle part  12 . Thus, the rainwater or the like cannot enter the battery pack  16 -side from the side where the inlet port  14 A and the opening H are located. In addition, the rainwater or the like having reached the seal member  70  flows down on an upper surface of the seal member  70  to be guided to the opening H. Thereafter, the rainwater or the like passes through the opening H to be discharged to the outside of the handle part  12 . Accordingly, the rainwater or the like cannot enter the battery pack  16 -side in the handle part  12 . 
     Effect of the Third Embodiment 
     In the impact driver  1 B of the third embodiment, the seal member  70  is twisted around the outer circumferential surface of the switch S, and the switch S is only accommodated in the handle part  12  while the seal member  70  is engaged with the ribs  18 L 1  and  18 R 1  using the rib guiding groove  71 , so that the seal member  70  can be positioned in the handle part  12 . Accordingly, the seal member  70  can be easily positioned. 
     Further, unlike the first and second embodiments, the rainwater or the like having entered inside of the handle part  12  through the inlet port  14 A and the opening H is discharged from the opening H to outside of the handle part  12  by using the opening H without additionally providing the drainage port  17  in the handle part  12 . As a result, the rainwater or the like can be prevented from entering a gap between the battery mounting part  13  and the battery pack  16 , and the battery pack  16 . 
     The present invention is not limited to the above-described embodiments, but can be implemented by appropriately changing a part of the configuration within a range without departing from the scope of the present invention. Unlike the first and second embodiments, the shape of each lateral surface of the seal member is not limited to the S-shape, but may be, for example, a shape that is linearly inclined from side where the inlet ports  14 A and R 1  and the opening H are located toward the battery pack  16 -side. 
     Further, in the case where the shape of each lateral surface of the seal member is linearly inclined, the shape of each rib protruding from the respective handle parts  12 L and  12 R may be changed to a shape enabling to press each of the linearly inclined lateral surfaces, unlike the above-described embodiments. In addition, the switch S may be accommodated in the handle part  12  by engaging a convex part provided on the entire circumference of the seal member  70  with concave parts provided on the entire circumferences of the both handle parts  12 L and  12 R, unlike the above-described embodiments. Alternatively, the switch S may be accommodated in the handle part  12  by directly engaging the seal member  70  with the concave parts provided on the entire circumferences of the both handle parts  12 L and  12 R without providing the convex part at the seal member  70 . Further, the present invention may be applied to not only the above-described impact drivers  1 ,  1 A, and  1 B, but also an electric tool such as a rechargeable hammer drill. 
     It is explicitly stated that all features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure as well as for the purpose of restricting the claimed invention independent of the composition of the features in the embodiments and/or the claims.