Patent Publication Number: US-11020846-B2

Title: Work tool

Description:
TECHNICAL FIELD 
     The present invention relates to a work tool and, more particularly, to a work tool having a main body to which an attachment device is connectable. 
     BACKGROUND ART 
     Conventionally, there are widely known work tools each configured to rotate and/or move an end bit, by driving force of a motor, to form a drill hole in a work piece or to apply an impact force to a work piece such as concrete. Among such work tools, there is also known a work tool having a tool main body to which an attachment device suitable for a work purpose is detachably attachable. For example, Patent Literature 1 discloses a drilling tool whose main body is detachably attachable with a dust collector as an example of such an attachment device. 
     CITATION LIST 
     [Patent Literature 1] Japanese Patent Application Publication No. 2009-136971 
     SUMMARY OF INVENTION 
     Technical Problem 
     An attachment device is connected to a main body of the tool when used. However, the tool main body and the attachment device connected thereto may not work well in cooperation with each other. Rather, in some cases, connection of the attachment device may result in deterioration in working efficiency. 
     The present invention has been made in view of the foregoing, and it is an object of the present invention to provide a work tool capable of realizing good cooperation between a tool main body and an attachment device connected thereto, for improving working efficiency. 
     Solution to Problem 
     In order to attain the above and other objects, the present invention provides a work tool including a main body and a controller configured to perform control over the main body. The main body includes a drive source and a work part configured to be driven by the drive source to perform a work. An attachment device is connectable to the main body. The controller is configured to: detect whether or not a connection of the attachment device to the main body is established; and change the control over the main body depending on whether or not the connection is established. 
     With this configuration, the controller is configured to appropriately change the control over the main body between a case where the attachment device is connected to the main body and a case where the attachment device is not connected to the main body. A suitable control over the main body can be realized depending on whether the main body is used alone or the main body is used with the attachment device connected thereto, thereby leading to enhancement of work efficiency. 
     In the configuration described above, it is preferable that: the main body further includes assisting means for assisting the work; and the controller is configured to further control an active state/non-active state of the assisting means depending on whether or not the connection is established. 
     With this configuration, the controller is configured to appropriately change whether or not the assisting means should be activated during a work depending on whether the main body is used alone or the main body is used with the attachment device connected thereto. Hence, the operation state of the assisting means while the work part is performing the work can be suitably controlled depending on whether or not the connection of the attachment device is available or not, thereby leading to improvement of working efficiency. Further, because the assisting means is put in the non-active state in which the assisting means is not activated during the work, power consumption can be reduced. 
     Further, in the configuration described above, it is preferable that: the controller places the assisting means in the active state in a case where the attachment device is not connected to the main body; and the controller places the assisting means in the non-active state in a case where the attachment device is connected to the main body. 
     With this configuration, such assisting means that need not be activated during a work or that may, if activated, deteriorate working efficiency of a work performed while being connected is configured to be activated only when the main body is used alone to perform the work, but not to be activated when the attachment device is connected. Accordingly, work efficiency during the connection of the attachment device can be enhanced, and an operator can perform the work comfortably. Further, since the assisting means that is not required to perform a work in the state where the attachment device is connected can be deactivated, power consumption can be reduced. 
     Further, in the configuration described above, it is preferable that: the assisting means is lighting means capable of irradiating light toward a work spot at which the working part performs the work; the attachment device is positioned between the lighting means and the work spot when connected to the main body; the controller places the lighting means in the active state during the work in the case where the attachment device is not connected to the main body; and the controller places the lighting means in the non-active state during the work in the case where the attachment device is connected to the main body. 
     With this configuration, the lighting means is turned off during a work performed in the state where the attachment device is connected. Thus, the connected attachment device neither bocks light of the lighting means, nor reflect the light in an unintended direction. Accordingly, work efficiency can be enhanced, and an operator can perform the work comfortably. Further, since the lighting means is configured not to be lit during a work performed when the attachment device is connected, power consumption can be reduced. 
     Further, preferably, the controller is configured to change control over driving of the driving source depending on whether or not the connection is established. 
     With this configuration, the controller is configured to appropriately change the control over the driving of the drive source between the case where the attachment device is connected to the main body and the case where the attachment device is not connected to the main body. Hence, a suitable control over the driving of the drive source can be realized depending on whether the main body is used alone or the main body is used with the attachment device connected thereto. Accordingly, when the attachment device is connected to the main body, the main body and the attachment device can suitably operate in cooperation with each other, thereby leading to enhancement of work efficiency. 
     Further, in the configuration described above, it is preferable that: the main body further includes a manipulation part configured to be subjected to a manual operation for controlling a start/stop of the drive source; the drive source is a motor; in a case where the attachment device is not connected to the main body, the controller causes a rotation speed of the motor to reach a target rotation speed after a lapse of a first time period from a timing when a starting operation is performed to the manipulation part; and, in a case where the attachment device is connected to the main body, the controller causes the rotation speed of the motor to reach the target rotation speed after a lapse of a second time period longer than the first time period from the timing when the starting operation is performed to the manipulation part. 
     With this configuration, normally, a certain time lag is generated from a timing when the attachment device is connected to the main body until a timing when the attachment device is driven fully enough to assist the work performed by the work part. However, a time period required for the rotation speed of the motor to reach the target rotation speed when the attachment device is connected is set longer than the time period required when the attachment device is not connected. Accordingly, the timing at which the connected attachment device is driven fully can be brought closer to the timing at which the rotation speed of the motor reaches the target rotation speed. Hence, it is unlikely that the motor of the main body is started to be driven to start the work before the attachment device is driven sufficiently. 
     Further, in the configuration described above, it is preferable that: the controller sets a maximum rotation speed of the drive source to a first rotation speed in the case where the attachment device is not connected to the main body; and the controller sets the maximum rotation speed of the drive source to a second rotation speed lower than the first rotation speed in the case where the attachment device is connected to the main body. 
     With this configuration, the controller makes the maximum rotation speed of the drive source lower when the attachment device is connected to the main body than when the attachment device is not connected. Accordingly, an amount of dust or the like generated as a result of the work by the work part can be reduced. This configuration is particularly effective in a case where a large amount of dust is assumed to be generated during the work, or in a case where a dust collector is connected to the main body as the attachment device. 
     Further, in the configuration described above, it is preferable that: the controller stops the attachment device after halting the drive source in a case where a stop operation is performed to the manipulation part. 
     With this configuration, when the stop operation is performed to the manipulation part, the attachment device is caused to stop after the drive source is halted. Normally, the work part is kept being driven for a while by inertia even after the drive source is stopped driving. Because the attachment device is configured to stop being driven after the driving of the drive source is halted, the attachment device can fully assist the work performed by the work part due to the inertia after the driving of the drive source is halted. 
     In particular, in a case where the attachment device is a dust collector configured to collect the dust generated as a result of the work, the above configuration is particularly effective because dust or the like generated until the work part comes to a complete stop after the drive source is stopped can be reliably disposed. Further, in a configuration where the drive source and the dust collector are to be stopped substantially at the same time as each other, the dust collector may be stopped before the sucked dust and the like is collected in a dust-collection case, with the dust left within the dust collector. In contrast, because the dust collector is caused to stop after the drive source is halted, the dust remaining in the dust collector can be reliably collected in the dust-collection case. 
     Further, it is preferable that: the main body further comprises an acceleration sensor configured to detect an acceleration of the main body; and the controller is configured to stop driving the drive source in a case where the acceleration detected by the acceleration sensor exceeds an acceleration threshold value. 
     With this configuration, the drive source is forced to stop being driven in the case where the acceleration of the main body exceeds the acceleration threshold value, for example, due to stall of the work part. Therefore, an excessive load is less likely to be impacted on the main body. 
     In the configuration described above, it is further preferable that the controller is configured to change the acceleration threshold value depending on whether or not the connection is established. 
     With this configuration, the acceleration threshold value can be set suitably depending on whether the main body is used alone or the main body is used with the attachment device connected thereto. Therefore, an excessive load is further less likely to be impacted on the main body. 
     Further, it is preferable that: the attachment device includes an attachment-device motor configured to be driven upon receipt of power supply from the main body in a state where the attachment device is connected to the main body, and switching means switchable between a first state allowing the power supply to the attachment-device motor and a second state interrupting the power supply; the main body includes a signal line connected to the switching means in the state where the attachment device is connected to the main body; the controller outputs, to the switching means, a control signal for bringing the switching means into the first state through the signal line to detect whether or not the attachment device is connected to the main body using the signal line. 
     With this configuration, the signal line for outputting the control signal can also be used to detect the connection of the attachment device. Therefore, there is no need to provide another signal line for the connection detection in addition to the signal line for outputting the control signal. Hence, the number of components required to manufacture the work tool can be reduced, thereby leading to lower manufacturing costs and improvement in assembly performance. 
     In the configuration described above, it is further preferable that: the attachment device further includes an attachment-device-side resistor connected to the signal line in the state where the attachment device is connected to the main body; the signal line includes a main-body-side resistor, one end of the main-body-side resistor being connected to the controller and another end of the main-body-side resistor being connected to the attachment-device-side resistor in the state where the attachment device is connected to the main body; and the controller detects whether or not the connection of the attachment device to the main body is established based on a value of a divided voltage divided by the attachment-device-side resistor and the main-body-side resistor. 
     With this configuration, the connection of the attachment device to the main body can be detected through a simple circuit architecture, without using complicated circuits. Hence, reduction in manufacturing costs and further improvement of assembly performance can be obtained. 
     Further, it is preferable that the attachment device is a dust collector configured to generate negative pressure at a work spot at which the work is performed by the work part. 
     With this configuration, even if the dust or the like is generated as a result of the work performed by the work part, the dust collector connected to the main body can suck and collect the generated dust, by utilizing the negative pressure. Thus, working efficiency can be enhanced. 
     Further, preferably, the work wool is a drilling tool. 
     In a case where the work tool is configured as a drilling tool that may generate a large amount of dust by the work of the work part, connecting, as the attachment device, a dust collector capable of sucking the generated dust to the main body can particularly improve working efficiency. 
     Advantageous Effects of Invention 
     According to the work tool of the present invention, a tool main body and an attachment device connected thereto can suitably work in cooperation with each other, and, hence, working efficiency can be enhanced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a left side view illustrating an exterior of a hammer drill according to one embodiment of the present invention. 
         FIG. 2  is a vertical cross-sectional view illustrating an internal structure of a main body of the hammer drill according to the embodiment of the present invention. 
         FIG. 3  is an external view illustrating a state where a dust collector is connected to the main body of the hammer drill according to the embodiment of the present invention. 
         FIG. 4  is a vertical cross-sectional view illustrating an internal structure in the state where the dust collector is connected to the main body of the hammer drill according to the embodiment of the present invention. 
         FIG. 5  is a partially enlarged cross-sectional view illustrating a state where terminals of the dust collector are inserted in terminals of the hammer drill according to the embodiment of the present invention. 
         FIG. 6  is a schematic circuit diagram including a block diagram illustrating electrical configurations of the hammer drill according to the embodiment of the present invention. 
         FIG. 7  is a flowchart explaining a main body control according to the embodiment of the present invention that is executed by a controller. 
         FIG. 8  is a timing chart illustrating a relationship among driving of a motor and various signals in the main body control according to the embodiment executed by the controller in a state where the dust collector is not connected. 
         FIG. 9  is a timing chart illustrating a relationship among driving of the motor and various signals in the main body control according to the embodiment executed by the controller in the state where the dust collector is connected. 
         FIG. 10  is a flowchart explaining a main body control according to a first modification to the embodiment of the present invention that is executed by the controller. 
         FIG. 11  is a timing chart illustrating a relationship among driving of the motor and various signals in the main body control according to the first modification to the embodiment executed by the controller in the state where the dust collector is connected. 
         FIG. 12  is a timing chart illustrating a relationship among driving of the motor and various signals in the main body control according to a second modification to the embodiment executed by the controller in the state where the dust collector is connected. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, one embodiment in which a work tool according to the present invention is applied to a cordless-type hammer drill  1  will be described in detail based on  FIGS. 1 through 9 . 
     The hammer drill  1  according to the present embodiment includes a main body  2  constituting an outer contour of the hammer drill  1 . As illustrated in  FIG. 1 , the main body  2  of the hammer drill  1  has one end portion (front end portion) at which an end-bit mount portion  10  is provided. To the end-bit mount portion  10 , an end bit  14  suitable for a work purpose, such as a drill blade, can be attached (see  FIG. 2 ). At another end portion of the main body  2  opposite to the one end portion at which the end-bit mount portion  10  is provided (rear end portion), a handle  11  is provided so that an operator can grip the same. The handle  11  is provided with a trigger switch  12  as an example of a manipulation part that the operator can manually operate. Incidentally, a side handle (not illustrated) is further attachable to the main body  2  for operations with both hands, depending on work purposes. 
     Further, a dust collector  100  as an example of an attachment device is detachably connectable to the main body  2  (see  FIG. 3 ). That is, the hammer drill  1  can be used in a state where the dust collector  100  is connected to the main body  2 , or can be used alone with the dust collector  100  detached from the main body  2 . 
     Hereinafter, the “front”, “rear”, “upward” and “downward” indicated by arrows in  FIG. 1  are defined as a front side, a rear side, an upper side, and a lower side of the hammer drill  1 . Further, the left when the hammer drill  1  is viewed from its rear side is defined as a left side of the hammer drill  1 , and the right as a right side thereof. 
     As illustrated in  FIG. 1 , a battery attachment portion  21  is provided below the handle  11  of the main body  2 . A battery  15  for supplying power to drive a motor  3  (to be described later) can be attached to and detached from the battery attachment portion  21 . Specifically, as indicated by a double-headed arrow A in  FIG. 1 , the battery  15  can be attached and detached relative to the battery attachment portion  21  in a front-rear direction of the main body  2 . In the present embodiment, two types of batteries  15  can be attached to the battery attachment portion  21  according to work purposes: one type of the battery  15  having an output voltage of 18 V, and the other type of the battery  15  having an output voltage of 36 V. In the present embodiment, the battery  15  is a battery pack configured of a plurality of secondary battery cells for power tools. 
     In a state where the battery  15  is attached to the battery attachment portion  21 , the operator holds the handle  11  and operates the trigger switch  12  while the end bit  14  mounted on the end-bit mount portion  10  is in abutment with a work piece. Thus, the hammer drill  1  can be driven cordlessly. The end-bit mount portion  10  and the end bit  14  mounted on the end-bit mount portion  10  are an example of a “work part” of the present invention. 
     A switch  13  is provided on a left side surface of the main body  2  for switching an operation mode of the hammer drill  1 . By operator&#39;s operation to the switch  13 , the operation mode of the hammer drill  1  can be switched to one from among the following operation modes: a rotational-impacting mode; an impacting mode; and a rotation mode. 
     The battery attachment portion  21  includes a battery-connecting terminal part  21 A (see  FIG. 6 ). The battery-connecting terminal part  21 A includes a plurality of terminals (not illustrated) electrically connectable to the battery  15  when the battery  15  is attached to the main body  2 . 
     Inside the handle  11  provided is a switching mechanism  12 A electrically connected to the trigger switch  12  and a control substrate part  7  (to be described later). When the trigger switch  12  is pulled, i.e., subjected to a starting operation (for example, when the trigger switch  12  is pushed toward the inside of the handle  11  by an operator&#39;s finger), the switching mechanism  12 A outputs a start-up signal for starting the motor  3  to the control substrate part  7 . Further, when the trigger switch  12  is released from being pulled, i.e., subjected to a stop operation (for example, when the operator detaches the finger from the trigger switch  12  to release the pulling operation), the switching mechanism  12 A stops outputting the start-up signal. 
     As illustrated in  FIG. 2 , the motor  3 , a switching circuit board  22 , a drive-transmission part  4 , an impact mechanism part  5 , a reciprocating-movement conversion part  6 , the control substrate part  7 , a light part  8 , and a power-supply part  9  are accommodated inside the main body  2 . 
     The motor  3  is an example of a drive source. The motor  3  is housed in a lower portion of the main body  2 . The motor  3  is a brushless motor serving as a drive source for the hammer drill  1 . The motor  3  is configured to be driven upon receiving power supplied from the battery  15  attached to the battery attachment portion  21 . The motor  3  is disposed with a rotation shaft  31  thereof oriented in a vertical direction. The motor  3  is rotatably supported by the main body  2 . A fan  32  is fixed to an upper end portion of the rotation shaft  31  of the motor  3 . 
     The switching circuit board  22  is a board having a ring shape in a bottom view. The switching circuit board  22  includes a switching circuit  22 A (see  FIG. 6 ) for driving the motor  3 . The switching circuit board  22  is disposed below the motor  3 . A lower end portion of the rotation shaft  31  is inserted in a through-hole formed at a substantially center portion of the switching circuit board  22  in a bottom view to penetrate the same vertically. Details of the switching circuit  22 A will be described later. 
     The drive-transmission part  4  is disposed above the motor in the main body  2 . The drive-transmission part  4  includes an intermediate shaft  41  extending in the front-rear direction. The intermediate shaft  41  is rotatably supported with respect to the main body  2 . The intermediate shaft  41  is connected to the rotation shaft  31  of the motor  3  through a plurality of gears so that the intermediate shaft  41  can rotate in response to receiving a rotational force from the motor  3 . 
     The impact mechanism part  5  is disposed above the drive-transmission part  4  in the main body  2 . The impact mechanism part  5  includes a cylinder  51 , a piston  52 , an impact member  53  and an intermediate member  54 . 
     The cylinder  51  has a substantially cylindrical shape extending in the front-rear direction. The cylinder  51  is supported at an upper portion of the main body  2  so as to be rotatable relative to the main body  2 . The cylinder  51  is engageable with the intermediate shaft  41  of the drive-transmission part  4 . The cylinder  51  is thus rotatable upon receiving a rotational force from the intermediate shaft  41  when engaged with the intermediate shaft  41 . The cylinder  51  has a distal end portion (front end portion) that is accommodated inside the end-bit mount portion  10 . 
     The piston  52  has a substantially cylindrical shape extending in the front-rear direction. The piston  52  is slidably movably disposed within the cylinder  51 . The impacting member  53  is disposed within the piston  52  so as to be slidably movable in the front-rear direction. The intermediate member  54  is disposed forward of the impacting member  53  within the cylinder  51  so as to be slidably movable in the front-rear direction. The impacting member  53  has a front end that can abut against a rear end of the intermediate member  54 , while the intermediate member  54  can abut against a rear end of the end bit  14  mounted on the end-bit mount portion  10 . 
     The reciprocating-movement conversion part  6  is arranged to connect the drive-transmission part  4  to the impact mechanism part  5 . The reciprocating-movement conversion part  6  includes an arm  61 . The arm  61  extends in a direction crossing the intermediate shaft  41  and the cylinder  51 . The arm  61  has an upper end portion connected to a rear end portion of the piston  52 , and a lower end portion connected to a rear portion of the intermediate shaft  41  through a plurality of balls. With this structure, the arm  61  can convert the rotational force of the motor  3  transmitted thereto through the intermediate shaft  41  into a linear reciprocating movement in the front-rear direction, and transmit the linear reciprocating movement to the piston  52 . The reciprocating movement of the arm  61  causes the piston  52  to reciprocate in the front-rear direction within the cylinder  51 . While air inside the cylinder  51  is being compressed and expanded by the reciprocating movement of the piston  52 , the impacting member  53  is caused to reciprocate in the front-rear direction. The reciprocating movement of the impacting member  53  then causes the front end of the impacting member  53  to abut against the rear end of the intermediate member  54  to strike the intermediate member  54 . When the intermediate member  54  is struck, the front end of the intermediate member  54  then hits the rear end of the end bit  14  attached to the end-bit mount portion  10 . In this manner, an impacting (striking) force is imparted to the end bit  14 . 
     The rotational force (drive force) of the motor  3  is transmitted to the impact mechanism part  5  as a rotational force, an impacting force, or a rotational-impacting force by the drive-transmission part  4  and/or the reciprocating-movement conversion part  6  being driven either simultaneously or selectively. With this configuration, the three operation modes of the hammer drill  1  can be achieved. 
     The control substrate part  7  is disposed above the battery attachment portion  21 . The control substrate part  7  includes a control circuit  71  (see  FIG. 6 ) configured to perform various controls for the main body  2 . The control circuit  71  is an example of a “controller” of the present invention. Details of the control circuit  71  will be described later. 
     The light part  8  is disposed forward and downward of the motor  3  in the main body  2 . The light part  8  is arranged to have a distal end (front end part) thereof exposed from a front surface of the main body  2 . In the present embodiment, the light part  8  is configured as an LED light. The light part  8  is electrically connected to the control substrate part  7 . The control substrate part  7  can thus provide control over lighting-on/lighting-off (activation/non-activation) of the light part  8 . While lighting, the light part  8  can emit LED light in a substantially upper-front direction of the main body  2 , i.e., toward a position where the end bit  14  applies machining to the work piece (work spot). The light part  8  is an example of “assisting means” and “lighting means” of the present invention. 
     In the present embodiment, when the hammer drill  1  is used alone, the light part  8  is placed in a light-on state (active state) by the control substrate part  7  to emit LED light toward the work spot near a tip end of the end bit  14 . This ensures operator&#39;s visibility during working. On the other hand, in a state where the dust collector  100  is connected to the main body  2 , the dust collector  100  is positioned between the light part  8  and the end bit  14 , as illustrated in  FIG. 3 . That is, the connected dust collector  100  is positioned on a light path of the LED light of the light part  8 , i.e., at a position blocking the LED light. Hence, in the present embodiment, when the dust collector  100  is connected to the main body  2 , the light part  8  is controlled by the control substrate part  7  to be put in a light-off state (non-active state) so as not to emit the LED light. Details will be described later. 
     The power-supply part  9  is provided below the light part  8  and at a lower-front end portion of the main body  2 . As illustrated in  FIG. 5 , the power-supply part  9  includes a main-body-side positive terminal  91 A, a main-body-side negative terminal  91 B, and a main-body-side signal terminal  91 C. The power-supply part  9  is configured to be connected to a collector-side terminal portion  115  (to be described later) of the dust collector  100  in a state where the dust collector  100  is connected to the main body  2 . By the connection between the power-supply part  9  of the main body  2  and the collector-side terminal portion  115  of the dust collector  100 , power can be supplied from the main body  2  to the dust collector  100  through the power-supply part  9 ; and the control substrate part  7  can have control over operations of the dust collector  100 . 
     Further, an acceleration sensor  23  is provided in the main body  2  (see  FIG. 6 ). The acceleration sensor  23  is electrically connected to the control substrate part  7  and is configured to detect acceleration of the main body  2 . The acceleration sensor  23  is configured to output an acceleration signal corresponding to the acceleration of the main body  2  to the control substrate part  7 . 
     As illustrated in  FIG. 3 , the dust collector  100  is detachably connectable to the main body  2  having the above configuration. The dust collector  100  is a device for sucking and collecting dusts generated from a work piece as a result of rotation/impacting of the end bit  14  such as a drill blade against the work piece. By connecting the dust collector  100  to the main body  2 , efficiency in working such as drilling performed by the hammer drill  1  can be expected to improve. In the present embodiment, the dust collector  100  is connected to the main body  2  of the hammer drill  1  from below. 
     Next, a configuration of the dust collector  100  will be described with reference to  FIGS. 3 through 5 . 
     As illustrated in  FIGS. 3 and 4 , the dust collector  100  mainly includes a body portion  110 , a slider portion  120 , and an adaptor portion  130 . 
     The body portion  110  includes a housing  111  constituting an outer contour thereof. In the housing  111 , a collector motor  112  serving as a drive source of the dust collector  100 , and a dust-collection case  113  collecting the sucked dust are accommodated. Further, the collector-side terminal portion  115  is provided at a rear portion of the housing  111 . 
     The collector motor  112  is disposed at the rear portion of the housing  111 . The collector motor  112  has a rotation shaft  112 A oriented in the front-rear direction. The collector motor  112  is supported by the housing  111  so as to be rotatable relative to the housing  111 . A fan  112 B is fixed to a front end of the rotation shaft  112 A of the collector motor  112 . By the collector motor  112  being driven to rotate the fan  112 B, a suction force of the dust collector  100  is generated. The collector motor  112  is an example of an “attachment-device motor” of the present invention. 
     The collector-side terminal portion  115  is provided at the rear portion of the housing  111  to protrude upward from an upper surface thereof. As illustrated in  FIG. 5 , the collector-side terminal portion  115  includes a collector-side positive terminal  116 A, a collector-side negative terminal  116 B, and a collector-side signal terminal  116 C in one-to-one correspondence with the three terminals of the power-supply part  9  of the main body  2 . 
     When the dust collector  100  is connected to the main body  2  of the hammer drill  1 , the collector-side positive terminal  116 A is received by the main-body-side positive terminal  91 A; the collector-side negative terminal  116 B is received by the main-body-side negative terminal  91 B; and the collector-side signal terminal  116 C is received by the main-body-side signal terminal  91 C. That is, in a state where the dust collector  100  is connected to the main body  2 , the collector-side positive terminal  116 A is connected to the main-body-side positive terminal  91 A; the collector-side negative terminal  116 B is connected to the main-body-side negative terminal  91 B; and the collector-side signal terminal  116 C is connected to the main-body-side signal terminal  91 C. The main body  2  and the dust collector  100  are thus electrically connected to each other through the power-supply part  9  and the collector-side terminal portion  115 . 
     The dust-collection case  113  is disposed forward of the collector motor  112  in the housing  111 . The dust-collection case  113  can be detachably attached to the body portion  110  (housing  111 ). Thus, the dust-collection case  113  can be taken out of the housing  111  for disposal of the dust when the collected dust has been accumulated to some extent. The dust-collection case  113  is provided with a filter  114 . The filter  114  is positioned to oppose the fan  112 B fixed to the front end of the rotation shaft  112 A of the collector motor  112  when the dust-collection case  113  is attached to the body portion  110 . 
     The slider portion  120  is supported by a front portion of the body portion  110  so as to be slidable in the front-rear direction relative thereto. Movement of the slider portion  120  in the front-rear direction is guided by a guide mechanism (not illustrated) formed in an inner side wall of the housing  111 . That is, the slider portion  120  is received in the body portion  110  when being moved rearward, and protrudes forward from the body portion  110  when being moved forward. As illustrated in  FIG. 4 , the slider portion  120  has a hollow space therein, and a hose  121  is accommodated in the hollow space. The hose  121  can expand and contract in the front-rear direction in association with the sliding movement of the slider portion  120  in the front-rear direction. The hose  121  defines a space  121   a  therein. The space  121   a  inside the hose  121  communicates with an internal space of the dust-collection case  113  attached to the body portion  110 . 
     The adaptor portion  130  is provided to extend upward from a front end portion of the slider portion  120 . The adaptor portion  130  is a portion that is pressed against the work piece during working. An opening (not illustrated) is formed at a tip end portion of the adaptor portion  130 , and the adaptor portion  130  defines a space  130   a  therein in communication with the opening. The space  130   a  communicates with the space  121   a  inside the hose  121  of the slider portion  120 . 
     In the dust collector  100  having the above configuration, dust sucked from the opening (not illustrated) formed in the tip end portion of the adaptor portion  130  is carried to the dust-collection case  113  through the space  121   a  in the hose  121  of the slider portion  120 , and then accumulated within the dust-collection case  113 . The dust in the sucked air is caught by the filter  114  provided in the dust-collection case  113 , so that the sucked dust is reliably accumulated in the dust-collection case  113  without being moved toward the collector motor  112 . The air filtered by the filter  114  is exhausted outside the dust collector  100  from an exhaust port (not illustrated) formed in the vicinity of the fan  112 B. 
     Next, electrical configurations of the hammer drill  1  and dust collector  100  will be described with reference to  FIG. 6 .  FIG. 6  is a circuit diagram including a block diagram illustrating the electrical configurations of the hammer drill  1  and dust collector  100 . 
     First, the electrical configuration of the hammer drill  1  will be described. As illustrated in  FIG. 6 , the main body  2  of the hammer drill  1  includes a positive line  24 , a GND line  25 , a first signal line  26  and a second signal line  27 , in addition to the above-described battery-connecting terminal part  21 A, power-supply part  9 , switching circuit  22 A, motor  3 , control circuit  71 , switching mechanism  12 A, acceleration sensor  23 , and light part  8 . 
     One end of each of the positive line  24 , GND line  25  and first signal line  26  is connected to the battery-connecting terminal part  21 A, while another end of each of the positive line  24 , GND line  25  and first signal line  26  is connected to the control circuit  71 . In a state where the battery  15  is attached to the battery attachment portion  21 , a voltage of the battery  15  (18 V in the present embodiment) is applied across the positive line  24  and the GND line  25 . When the battery  15  outputs a battery-protection signal, the battery-protection signal is inputted to the control circuit  71  through the first signal line  26 . In this case, the control circuit  71  stops the motor  3 . 
     The second signal line  27  connects the main-body-side signal terminal  91 C of the power-supply part  9  to the control circuit  71 . The second signal line  27  includes a main-body-side voltage dividing resistor  27 A. The main-body-side voltage dividing resistor  27 A is provided on the second signal line  27 . The second signal line  27  has one end connected to the control circuit  71 , and another end connected to the main-body-side signal terminal  91 C. A node  27 B between the main-body-side voltage dividing resistor  27 A on the second signal line  27  and the main-body-side signal terminal  91 C is connected to the control circuit  71 . The second signal line  27  is an example of a “signal line” of the present invention. The main-body-side voltage dividing resistor  27 A is an example of a “main-body-side resistor” of the present invention. 
     The main-body-side positive terminal  91 A and the main-body-side negative terminal  91 B of the power-supply part  9  are connected to the positive line  24  and the GND line  25 , respectively. 
     The switching circuit  22 A is a circuit configured to supply power of the battery  15  to the motor  3 . The switching circuit  22 A is connected between the positive line  24  and GND line  25  and the motor  3 . The switching circuit  22 A includes six switching elements (not illustrated). In the present embodiment, these six switching elements are six FETs. The six FETs are connected in a three-phase bridge configuration, with each gate thereof connected to the control circuit  71 ; and with each drain or source thereof connected to the motor  3 . The six switching elements (FETs) perform switching operations to rotate the rotation shaft  31  of the motor  3  in a predetermined rotation direction based on drive signals (gate signals) outputted from the control circuit  71 . 
     The control circuit  71  is a circuit configured to perform a main body control of the hammer drill  1 . The control circuit  71  includes: a CPU for performing arithmetic operations based on a process program and various data used for the main body control; a ROM (not illustrated) for storing the process program, various data and various threshold values; a memory including a RAM (not illustrated) for temporarily storing data; and a timing part for measuring time. In the present embodiment, the control circuit  71  includes a microcomputer. 
     The control circuit  71  is configured to control the driving of the motor  3  as the main body control. In controlling the driving of the motor  3 , on the basis of a rotational position signal outputted from a rotational position detection circuit (not illustrated), the control circuit  71  outputs, to the switching circuit  22 A, drive signals for sequentially switching FETs to be rendered ON among the six FETs, thereby rotating the rotating shaft  31  of the motor  31  in the predetermined rotation direction. Further, the control circuit  71  is configured to adjust power supply to the motor  3  to thereby control a rotation speed of the rotation shaft  31 . As the rotation speed control, the control circuit  71  is configured to: control a time period from a time when the motor  3  starts to be driven to a time when the rotation speed of the motor  3  reaches a prescribed target rotation speed; and perform a constant speed control after reaching the prescribed target rotation speed. In the constant speed control, the control circuit  71  controls the rotation speed of the motor  3  so that the rotation speed can be maintained at the prescribed target rotation speed. Note that the controlling of the rotation speed is performed by outputting, as PWM drive signals, drive signals for driving (switching on) predetermined three FETs of the switching circuit  22 A (PWM control). Further, the control circuit  71  controls the start/stop of the motor  3  based on the start-up signal outputted from the switching mechanism  12 A. 
     Further, as the main body control, the control circuit  71  is configured to: detect whether or not the dust collector  100  is connected to the main body  2  (hereinafter, referred to as “connection detection”); and control activation/non-activation (i.e., light-on/light-off) of the light part  8  based on a result of the connection detection. Details of the connection detection will be described later. Further, the control circuit  71  is configured to stop driving the motor  3  when the acceleration sensor  23  detects that the acceleration of the main body  2  exceeds a predetermined acceleration threshold value while the motor  3  is being driven. 
     Further, the control circuit  71  is configured to control driving of the collector motor  112  in the state where the dust collector  100  is connected to the main body  2 . The control over the collector motor  112  is performed by outputting a dust-collector drive signal to the second signal line  27  to output the dust-collector drive signal to the dust collector  100  connected to the main body  2  through the main-body-side signal terminal  91 C and collector-side signal terminal  116 C. The dust-collector drive signal is an example of a “control signal” of the present invention. 
     Next, the electrical configuration of the dust collector  100  will be described. As illustrated in  FIG. 6 , the dust collector  100  includes an FET  140  and a dust-collector-side voltage dividing resistor  141 , in addition to the above-described collector motor  112  and collector-side terminal portion  115 . 
     The collector motor  112  is connected, through the FET  140 , to the collector-side positive terminal  116 A and collector-side negative terminal  116 B of the collector-side terminal portion  115 . That is, in the state where the dust collector  100  is connected to the main body  2 , the collector motor  112  is connected to the positive line  24  and GND line  25  of the main body  2  through the FET  140 . Thus, when the FET  140  is rendered ON (in a state where power supply to the collector motor  112  is allowed), the power of the battery  15  attached to the main body  2  is supplied to the collector motor  112 , thereby driving the collector motor  112 . On the other hand, when the FET  140  is rendered OFF (in a state where power supply to the collector motor  112  is shut off), the power of the battery  15  attached to the main body  2  is not supplied to the collector motor  112 , thereby halting the collector motor  112 . The FET  140  is an example of “switching means” in the present invention. The ON-state of the FET  140  is an example of a “first state”, and the OFF state thereof is an example of a “second state” in the present invention. 
     The dust-collector-side voltage dividing resistor  141  is connected between the gate and the source of the FET  140 . A connecting point  142  through which the dust-collector-side voltage dividing resistor  141  and the gate of the FET  140  are connected to each other is connected to the collector-side signal terminal  116 C. That is, in the state where the dust collector  100  is connected to the main body  2 , the gate of the FET  140  is connected to the control circuit  71  through the main-body-side signal terminal  91 C and collector-side signal terminal  116 C. In the present embodiment, the FET  140  is rendered ON while the control circuit  71  is outputting the dust-collector drive signal to the gate of the FET  140  through the main-body-side signal terminal  91 C and collector-side signal terminal  116 C; and the FET  140  is rendered OFF while the control circuit  71  is not outputting the dust-collector drive signal. The dust-collector-side voltage dividing resistor  141  is an example of an “attachment-device-side resistor” in the present invention. 
     Here, the connection detection by the control circuit  71  will be described. The control circuit  71  performs the connection detection using a value of the voltage (connection determination voltage) that appears at the node  27 B on the second signal line  27 . More specifically, the control circuit  71  outputs the dust-collector drive signal to the second signal line  27  to determine whether the dust collector  100  is connected to the main body  2 . The control circuit  71  determines that the dust collector  100  is not connected to the main body  2  when the voltage appearing at the node  27 B while the dust-collector drive signal is being outputted is higher than a predetermined voltage threshold value, whereas the control circuit  71  determines that the dust collector  100  is connected to the main body  2  when the voltage appearing at the node  27 B while the dust-collector drive signal is being outputted is lower than the predetermined voltage threshold value. 
     In the present embodiment, the dust-collector drive signal is a voltage signal of substantially 5 V. When the dust-collector drive signal (5 V) is outputted to the second signal line  27  in a state where the dust collector  100  is not connected to the main body  2 , the voltage appearing at the node  27 B (i.e., the connection determination voltage) is substantially 5 V. On the other hand, when the dust-collector drive signal (5 V) is outputted to the second signal line  27  in the state where the dust collector  100  is connected to the main body  2 , the dust-collector drive signal is divided by the main-body-side voltage dividing resistor  27 A and the dust-collector-side voltage dividing resistor  141 . Here, the resistance ratio between the main-body-side voltage dividing resistor  27 A and the dust-collector-side voltage dividing resistor  141  is set such that substantially 4 V appears at the node  27 B as a divided voltage, i.e., as the connection determination voltage. Thus, a value between 5 V and 4 V (4.5 V in the present embodiment) is used as the predetermined voltage threshold value. Hence, the control circuit  71  determines that the dust collector  100  is not connected to the main body  2  when the voltage appearing at the node  27 B while the dust-collector drive signal is being outputted is equal to or higher than 4.5 V, whereas the control circuit  71  determines that the dust collector  100  is connected to the main body  2  when the voltage appearing at the node  27 B is lower than 4.5 V. 
     Next, the main body control performed by the control circuit  71  (control substrate part  7 ) will be described while referring to the flowchart of  FIG. 7 . 
     When the battery  15  is attached to the battery attachment portion  21 , power is supplied to the control circuit  71 , and the control circuit  71  starts executing the main body control. After starting the main body control, the control circuit  71  determines whether or not the starting operation (pulling operation) to the trigger switch  12  is performed (S 101 ). Specifically, the control circuit  71  determines whether or not the trigger switch  12  is subjected to the starting operation based on presence/absence of the start-up signal from the switching mechanism  12 A. 
     When determining that the trigger switch  12  is not subjected to the starting operation (S 101 :NO), the control circuit  71  performs the determination of S 101  again. That is, the control circuit  71  waits until the starting operation to the trigger switch  12  is performed while repeating the determination of S 101 . On the other hand, when determining that the starting operation to the trigger switch  12  is performed (S 101 :YES), the control circuit  71  outputs the dust-collector drive signal for driving the dust collector  100  to the second signal line  27  (S 102 ). 
     Then, the control circuit  71  detects the connection determination voltage appearing at the node  27 B on the second signal line  27  (S 103 ), and determines, based on the detected connection determination voltage, whether or not the dust collector  100  is connected to the main body  2  (S 104 ). That is, the control circuit  71  performs the connection detection in S 103  and S 104 . Specifically, the control circuit  71  determines that the dust collector  100  is not connected to the main body  2  when the connection determination voltage is equal to or higher than 4.5 V; and the control circuit  71  determines that the dust collector  100  is connected to the main body  2  when the connection determination voltage is lower than 4.5 V. The result of the connection detection in S 103  and S 104  is temporarily stored in the non-illustrated memory (RAM) of the control circuit  71  as connection detection information about the connection/non-connection of the dust collector  100 . 
     When determining that the dust collector  100  is not connected to the main body  2  (S 104 : NO), the control circuit  71  stops outputting the dust-collector drive signal (S 105 ). That is, the control circuit  71  once outputs the dust-collector drive signal for the connection detection. In the case where the dust collector  100  is not connected to the main body  2 , since there is no need to continue outputting the dust-collector drive signal for driving the dust collector  100 , the control circuit  71  stops outputting the dust-collector drive signal upon completion of the connection detection. 
     The control circuit  71  then sets the light part  8  to the light-on state (activated state) (S 106 ). When the LED light of the light part  8  is turned on, the work spot at which the end bit  14  applies machining (near the tip end of the end bit  14 ) is illuminated by the LED light. 
     After illuminating the light part  8 , the control circuit  71  starts driving the motor  3  (S 108 ). 
     On the other hand, when determining in S 104  that the dust collector  100  is connected to the main body  2  (S 104 :YES), the control circuit  71  determines whether or not one second has elapsed from a point of time when the starting operation to the trigger switch  12  was determined to be performed in S 101  (since when “YES” determination is made in S 101 ) (S 107 ). 
     When determining that one second has not yet elapsed from the point of time when the starting operation to the trigger switch  12  was performed (S 107 :NO), the control circuit  71  performs the determination of S 107  again. That is, the control circuit  71  repeats the determination of S 107  until one second is determined to have elapsed from when the trigger switch  12  was subjected to the starting operation. 
     When determining that one second has elapsed since the execution of the starting operation to the trigger switch  12  (S 107 :YES), the control circuit  71  starts driving the motor  3  (S 108 ). That is, in the case where the dust collector  100  is connected to the main body  2 , the control circuit  71  is configured to delay the starting of the motor  3  by one second as compared to a case where the dust collector  100  is not connected to the main body  2 . This will be referred to as “start delay processing”. Once the driving of the motor  3  is started, the end bit  14  is driven. When the driven end bit  14  is made to abut against the work piece, working such as drilling can be applied to the work piece. 
     After starting to drive the motor  3  (S 108 ), the control circuit  71  then determines whether or not the starting operation for the trigger switch  12  has been released (S 109 ). The control circuit  71  makes the determination on whether the starting operation is released based on the presence/absence of the start-up signal from the switching mechanism  12 A. Specifically, the control circuit  71  determines that the starting operation for the trigger switch  12  is released at a point of time when the output of the start-up signal from the switching mechanism  12 A is stopped. 
     When determining that the starting operation for the trigger switch  12  has not been released (S 109 :NO), the control circuit  71  performs the determination of S 109  again. That is, the control circuit  71  continues driving the motor  3  until the starting operation for the trigger switch  12  is released while repeating the determination of S 109 . 
     When the starting operation for the trigger switch  12  is determined to have been released (S 109 :YES), the control circuit  71  determines whether the dust collector  100  is connected to the main body  2  (S 110 ). That is, the connection detection is performed in S 110 . Specifically, in the connection detection performed in S 110 , the control circuit  71  refers to the connection detection information obtained and stored in the non-illustrated memory (RAM) (not illustrated) in the determination of S 104 . That is, in S 110 , the control circuit  71  does not perform the same processing as S 104  but determines whether or not the dust collector  100  is connected by utilizing the result of the connection detection that was already obtained in S 104 . 
     When the dust collector  100  is determined not to be connected to the main body  2  (S 110 : NO), the control circuit  71  stops driving the motor  3  (S 111 ) and sets the LED light of the light part  8  to the turned-off state (non-active state) (S 112 ). After turning off the LED light of the light part  8 , the control circuit  71  waits for the operator to perform the starting operation for the trigger switch  12  while repeating the determination of S 101 . 
     On the other hand, when the dust collector  100  is connected to the main body  2  (S 110 : YES), the control circuit  71  stops driving the motor  3  in S 113 . 
     After stopping driving the motor  3 , the control circuit  71  determines in S 114  whether or not ten seconds has elapsed from a point of time when the driving of the motor  3  was stopped in S 113 . When determining that ten seconds has not elapsed from the point of time when the driving of the motor  3  was stopped (S 114 :NO), the control circuit  71  repeats the determination of S 114  until ten seconds elapses. 
     When determining that ten seconds has elapsed from the point of time when the driving of the motor  3  was stopped (S 114 :YES), the control circuit  71  stops, in S 115 , outputting the dust-collector drive signal that has been outputted continuously since S 102 . When the output of the dust-collector drive signal is terminated, the FET  140  of the dust collector  100  is rendered OFF to stop the driving of the collector motor  112 . The driving of the dust collector  100  is thus ended. That is, the control circuit  71  is configured to stop driving the collector motor  112  of the dust collector  100  after stopping driving the motor  3  of the main body  2 . This processing will be referred to as “stop delay processing”. After the collector motor  112  is halted, the control circuit  71  waits for the operator to perform the starting operation for the trigger switch  12  while repeating the determination of S 101 . 
     Here, relationship between the driving of the motor  3  and various signals in the above-described main body control performed by the control circuit  71  will be described using the timing charts of  FIGS. 8 and 9 . 
     First, with reference to  FIG. 8 , a case where the dust collector  100  is not connected to the main body  2  will be described. 
     When the starting operation is performed to the trigger switch  12  at a timing t 1 , the motor  3  starts to be driven. Note that, at the timing t 1 , the control circuit  71  performs: output of the dust-collector drive signal; detection of the connection determination voltage (substantially 5 V); the connection detection based on the detected connection determination voltage; and halt of the output of the dust-collector drive signal. These correspond to the processing of: from S 101 :YES to S 104 :NO, S 105 , and S 108  in the flowchart of  FIG. 7 . Further, at the timing t 1 , the LED light of the light part  8  is turned on (corresponding to the processing of S 106  in the flowchart of  FIG. 7 ). 
     In this timing chart, in order to facilitate description, the output of the dust-collector drive signal, the detection of the connection determination voltage, the connection detection, the halt of the output of the dust-collector drive signal, the lighting-on of the light part  8 , and the driving of the motor  3  are all assumed to be performed at the timing t 1 . Actually, however, the output of the dust-collector drive signal, the detection of the connection determination voltage, the connection detection, the halt of the output of the dust-collector drive signal, the lighting-on of the light part  8 , and the driving of the motor  3  are performed sequentially in this order in a very short period of time. 
     Once the driving of the motor  3  is started at the timing t 1 , the rotation speed of the motor  3  reaches a prescribed target rotation speed N 1  at a timing t 2  after a lapse of a time period T 1  from the timing t 1 . 
     Thus, in the case where the dust collector  100  is not connected to the main body  2 , the control circuit  71  controls the driving of the motor  3  such that the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  after the time period T 1  has elapsed from when the starting operation is performed for the trigger switch  12 . In other words, a time period required for the rotation speed of the motor  3  to reach the prescribed target rotation speed N 1  from when the starting operation is performed for the trigger switch  12  (hereinafter, referred to as “arrival required time period”) is the time period T 1 . 
     After the rotation speed reaches the prescribed target rotation speed N 1  at the timing t 2 , the control circuit  71  continues driving the motor  3  with the rotation speed thereof maintained at the target rotation speed N 1  under constant rotation speed control. Thereafter, when the starting operation for the trigger switch  12  is released at a timing t 3 , the driving of the motor  3  is halted at this point of time. This corresponds to the processing of S 109 :YES, S 110 :NO, and S 111  in the flowchart of  FIG. 7 . Further, at the timing t 3  when the starting operation for the trigger switch  12  is released, the LED light of the light part  8  is also turned off (corresponding to processing of S 112  in the flowchart of  FIG. 7 ). 
     On the other hand, referring to  FIG. 9 , in a case where the dust collector  100  is connected to the main body  2 , when the starting operation is performed for the trigger switch  12  at a timing t 11 , the control circuit  71  outputs the dust-collector drive signal, and a voltage of substantially 4 V is detected as the connection determination voltage. This corresponds to the processing from S 101 :YES to S 103  in the flowchart of  FIG. 7 . 
     Because the dust collector  100  is connected to the main body  2 , the driving of the motor  3  is started at a timing t 12  after a lapse of one second from the timing t 11 . This corresponds to the processing of S 104 :YES, S 107 , and S 108  in the flowchart of  FIG. 7 . When the motor  3  starts to be driven, the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  at a timing t 13  after a lapse of a time period T 2  from the timing t 11 . 
     In this way, in the case where the dust collector  100  is connected to the main body  2 , the control circuit  71  controls the driving of the motor  3  such that the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  after the lapse of the time period T 2  from when the starting operation is performed for the trigger switch  12 . In other words, the arrival required time period when the dust collector  100  is connected to the main body  2  is the time period T 2 . 
     Note that, in the present embodiment, a required time period from when the motor  3  is started until when the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  is constant regardless of whether the dust collector  100  is connected or disconnected relative to the main body  2 . That is, the required time period in  FIG. 8  (time period between the timing t 1  and timing t 2 ) and the required time period in  FIG. 9  (time period between the timing t 12  and timing t 13 ) are identical to each other. However, the arrival required time period differs depending on whether the dust collector  100  is connected or disconnected relative to the main body  2 . This is because the start delay processing (S 107 ) is performed when the dust collector  100  is connected to the main body  2 , while the start delay processing is not performed when the dust collector  100  is not connected. That is, the time period T 2  (i.e., the arrival required time period with execution of the start delay processing when the dust collector  100  is connected) is longer than the time period T 1  (i.e., the arrival required time period when the dust collector  100  is not connected). The time period T 1  is an example of a “first time period” in the present invention, and the time period T 2  is an example of a “second time period” in the present invention. 
     That is, in the main body control according to the present embodiment, there is no difference in the control to be performed after the motor  3  starts to be driven between the two cases; however, focusing on the point of time when the starting operation for the trigger switch  12  is performed, the rotation speed of the motor  3  is so configured to reach the target rotation speed N 1  at a later timing when the dust collector  100  is connected than when the dust collector  100  is not connected. 
     After the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  at the timing t 13 , the control circuit  71  continues to drive the motor  3  with the rotation speed thereof maintained at the target rotation speed N 1  under the constant rotation speed control. When the starting operation for the trigger switch  12  is released thereafter at a timing t 14 , the driving of the motor  3  is halted. This corresponds to the processing of S 109 :YES, S 110 :YES, and S 113  in the flowchart of  FIG. 7 . 
     Even after the driving of the motor  3  is stopped at the timing t 14 , the dust-collector drive signal is kept being outputted for a period of ten seconds (corresponding to the processing of S 114 :NO in  FIG. 7 ). That is, the output of the dust-collector drive signal is halted at a timing t 15  after a lapse of 10 seconds from the timing t 14 . This corresponds to the stop delay processing from S 114 :YES to S 115  in the flowchart of  FIG. 7 . Note that, in response to the halt of the output of the dust-collector drive signal, the output of the connection determination voltage from the node  27 B to the control circuit  71  is also halted at the timing t 15 . 
     As described above, in the main body control according to the present embodiment, the control circuit  71  is configured to detect whether or not the dust collector  100  is connected to the main body  2  by referring to the connection determination voltage, and to change the control for the main body  2  depending on whether or not the dust collector  100  is connected. That is, the control over the main body  2  can be changed appropriately between the case where the dust collector  100  is connected to the main body  2  and the case where the dust collector  100  is disconnected from the main body  2 . Thus, the operations of the hammer drill  1  can be controlled appropriately according to the connection status thereof to the dust collector  100 : whether the hammer drill  1  is used alone or where the hammer drill  1  is used with the dust collector  100  connected to the main body  2 . Hence, improved working efficiency can be realized. 
     In general, attachment devices are often developed so as to be light-weighted, inexpensive, and versatile. Hence, there are limited variations available as specifications for each attachment device, and designing attachment devices suitable for each working tool is difficult to realize. However, according to the main body control of the present embodiment, the main body control is performed by the control circuit  71  of the main body  2  to which the dust collector  100  is connectable so that the main body control can be made variant appropriately depending on whether or not the dust collector  100  is connected to the main body  2 . This configuration can improve working efficiency of the hammer drill  1  with the dust collector  100  connected thereto, while maintaining versatility in structure of the dust collector  100  as the attachment device. 
     Further, in the present embodiment, the control circuit  71  is configured to control whether the light part  8  as the assisting means should be set to the active state or the non-active state in a work initiated by the starting operation to the trigger switch  12  based on the connection status of the dust collector  100  relative to the main body  2 . That is, whether to activate the light part  8  or not can be appropriately determined depending on whether the hammer drill  1  is used alone or used with the dust collector  100  connected to the main body  2 . Thus, this configuration can provide suitable control over the operation state of the light part  8  during the work depending on whether or not the connection of the dust collector  100  is established, thereby leading to improvement of working efficiency. 
     Specifically, in the present embodiment, the control circuit  71  places the light part  8  into the light-on state (active state) during the work when the dust collector  100  is not connected to the main body  2 , while placing the light part  8  into the light-off state (non-active state) during the work when the dust collector  100  is connected to the main body  2 . 
     In a configuration where the dust collector  100  connected to the main body  2  is positioned between the tip end of the end bit  14  (as the work part) and the light part  8  as in the present embodiment, when the LED light is emitted from the light part  8  while the dust collector  100  is connected to the main body  2 , the emitted LED light may be blocked by the connected dust collector  100  or the emitted LED light may be reflected in an unintended direction, which may hinder the work. In order to cope with this problem, the light part  8  (lighting means) is set to the light-off state (non-active state) when the dust collector  100  is connected in the present embodiment, because the activation of the light part  8  may result in deterioration in working efficiency. This configuration can prevent occurrence of any inconvenience attributed to the LED light. Further, power consumption can be reduced, because the light part  8  is placed in the light-off state. 
     Further, when the hammer drill  1  is used alone, the light part  8  is configured to be illuminated. Hence, operator&#39;s visibility in working can be ensured. 
     Further, in the present embodiment, the control circuit  71  can change the drive control over the motor  3  depending on availability of the connection of the dust collector  100  relative to the main body  2 . That is, the control circuit  71  can provide the drive control for the motor  3  as appropriate in a different manner between the case where the dust collector  100  is connected to the main body  2  and the case where the dust collector  100  is not connected to the main body  2 . 
     As a result, the configuration of the embodiment can provide the drive control over the motor  3  suitably for each of the case where the hammer drill  1  is used alone and the case where the hammer drill  1  is used with the dust collector  100  connected to the main body  2 . Accordingly, the dust collector  100  and main body  2  can be operated in good cooperation with each other in the state where the dust collector  100  is connected to the main body  2 , leading to improvement in working efficiency. 
     The “main body control” of the present invention is a concept that includes not only the drive control for the motor  3  by the control circuit  71  (control substrate part  7 ), but also the control over the assisting means as described above. 
     Further, in the main body control according to the present embodiment, the control circuit  71  controls the rotation speed of the motor  3  to reach the target rotation speed N 1  after the lapse of the time period T 1  from when the starting operation is performed for the trigger switch  12  when the dust collector  100  is not connected to the main body  2 , while the control circuit  71  controls the rotation speed of the motor  3  to reach the target rotation speed N 1  after the lapse of the time period T 2  longer than the time period T 1  from when the starting operation is performed for the trigger switch  12  when the dust collector  100  is connected to the main body  2 . 
     In a case where a dust collector as the attachment device is connected to a main body of a work tool, usually a certain time lag is generated between a timing when the dust collector is connected and a timing when a negative pressure is generated within the dust collector. Thus, if the motor is controlled in the same way as each other regardless of whether the dust collector is connected or disconnected, conceivably, the motor may be driven to initiate machining before a sufficient sucking force is generated in the dust collector. However, in the present embodiment, the time period T 2  required for the rotation speed of the motor  3  to reach the target rotation speed N 1  after the starting operation is performed for the trigger switch  12  when the dust collector  100  is connected is set longer than the time period T 1  required when the dust collector  100  is not connected. That is, referring to the point of time when the starting operation is performed for the trigger switch  12 , the rotation speed of the motor  3  reaches the target rotation speed N 1  later when the dust collector  100  is connected than when the dust collector  100  is not connected. With this configuration, the timing at which the connected dust collector  100  is driven to generate a sufficient negative pressure can be brought closer to the timing at which the rotation speed of the motor  3  reaches the target rotation speed N 1 . Thus, the motor  3  of the main body  2  can be suppressed from starting to be driven before the dust collector  100  is driven sufficiently. 
     Further, in the main body control according to the present embodiment, when the starting operation for the trigger switch  12  is released, the dust collector  100  is caused to stop after the motor  3  is halted (stop delay processing). 
     Normally, the end bit  14  supported by the end-bit mount portion  10  driven by the motor  3  is kept being driven for a while by inertia even after the driving of the motor  3  is stopped. In the present embodiment, the dust collector  100  is stopped after the driving of the motor  3  of the main body  2  is stopped (after the lapse of 10 seconds from the time when the driving of the motor  3  is halted in the present embodiment). Accordingly, dust or the like generated as a result of the driving of the end bit  14  until the end bit  14  completely stops after the motor  3  is stopped can be reliably collected by the dust collector  100 . 
     In a configuration where the motor  3  and the collector motor  112  of the dust collector  100  are configured to be stopped substantially at the same time, conceivably, the dust collector  100  may be caused to stop before the sucked dust and the like is collected in the dust-collection case  113 , with the dust left in the space  121   a  of the hose  121  or in the space  130   a  of the adaptor portion  130 . In contrast, because the dust collector  100  is configured to be stopped after the motor  3  of the main body  2  is halted in the present embodiment, the dust remaining in the dust collector  100  can be reliably collected in the dust-collection case  113 . 
     Further, the hammer drill  1  according to the present embodiment includes the acceleration sensor  23  for detecting the acceleration of the main body  2 . The control circuit  71  is configured to stop driving the motor  3  when the acceleration detected by the acceleration sensor  23  exceeds the predetermined acceleration threshold value. 
     With this configuration, the motor  3  is forced to stop driving when the acceleration of the main body  2  exceeds the predetermined acceleration threshold value, for example, due to stall of the end bit  14  driven by the motor  3  during a work. An excessive load is thus less likely to be imparted on the main body  2 . 
     Further, in the present embodiment, the dust collector  100  includes the collector motor  112  and the FET  140 . The collector motor  112  is configured to be driven in response to receipt of power supply from the main body  2  connected thereto. The FET  140  is switchable between an ON state where power supply to the collector motor  112  is allowed and an OFF state where power supply to the collector motor  112  is shut off. The main body  2  includes the second signal line  27  connected to the FET  140  in the state where the main body  2  is connected to the dust collector  100 . The control circuit  71  is configured to: output, to the FET  140 , the dust-collector drive signal for rendering the FET  140  ON through the second signal line  27 ; and perform the connection detection to detect whether the dust collector  100  is connected to the main body  2  using the second signal line  27 . 
     That is, the second signal line  27  that is used to output the dust-collector drive signal for switching between the ON and OFF states of the FET  140  can also be used to perform the connection detection for detecting the connection status of the dust collector  100 . This configuration can eliminate the need to provide another signal line for the connection detection in addition to the second signal line  27 . This configuration can therefore reduce the number of components required to manufacture the hammer drill  1 , thereby leading to lower manufacturing costs and improvement of assembly performance. 
     Further, the dust collector  100  further includes the dust-collector-side voltage dividing resistor  141  connected to the second signal line  27  in the state where the dust collector  100  is connected to the main body  2 . The second signal line  27  of the main body  2  includes the main-body-side voltage dividing resistor  27 A having one end connected to the control circuit  71  and another end connected to the dust-collector-side voltage dividing resistor  141  in the state where the dust collector  100  is connected to the main body  2 . The control circuit  71  is configured to perform the connection detection for detecting the connection status of the dust collector  100  relative to the main body  2  based on the value of the divided voltage divided by the dust-collector-side voltage dividing resistor  141  and the main-body-side voltage dividing resistor  27 A (i.e., based on the voltage appearing at the node  27 B). 
     With this configuration, the connection/non-connection of the dust collector  100  relative to the main body  2  can be detected with a simple circuit configuration. Further reduction in manufacturing costs and further improvement of assembly performance can be obtained. 
     Further, in the present embodiment, as the attachment device, the dust collector  100  can be attached to and detached from the main body  2  for generating the negative pressure at the work spot at which the end bit  14  applies machining. 
     Thus, the dust or the like generated as a result of the machining performed by the end bit  14  can be sucked and collected by utilizing the negative pressure of the connected dust collector  100  as the attachment device. Improved working efficiency can be obtained. In particular, just as the hammer drill  1  of the present embodiment, in a case where the work tool is a drilling tool that may generate a large amount of dust by the working of the end bit  14 , connecting the dust collector  100 , as the attachment device, to the main body  2  can obtain further improved working efficiency because the connected dust collector  100  can suck and collect the generated dust. 
     While the main body control according to the present embodiment has been described, the main body control according to the present invention is not limited to the described one. Hereinafter, a main body control according to a first modification to the depicted embodiment will be described with reference to a flowchart of  FIG. 10 . 
     The main body control according to the first modification differs from the main body control of the above embodiment in processing to be performed during a period from when the starting operation for the trigger switch  12  is performed until when the motor  3  starts to be driven. 
     Specifically, upon starting the main body control, the control circuit  71  determines whether or not the starting operation has been performed for the trigger switch  12  (S 201 ). When determining that the starting operation has been performed for the trigger switch  12  (S 201 :YES), the control circuit  71  outputs the dust-collector drive signal to the second signal line  27  (S 202 ) and detects the connection determination voltage (S 203 ). Then, the control circuit  71  performs the connection detection to determine whether or not the dust collector  100  is connected to the main body  2  based on the connection determination voltage detected in S 203  (S 204 ). The above processing from S 201  to S 204  is the same as the processing from S 101  to S 104  of the flowchart of  FIG. 7  in the main body control according to the above embodiment. 
     When determining in S 204  that the dust collector  100  is not connected to the main body  2  (S 204 :NO), the control circuit  71  stops outputting the dust-collector drive signal (S 205 ). 
     Then, in S 206 , the control circuit  71  sets a time period from a time when the motor  3  starts to be driven to a time when the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  (target-rotation-speed arrival time period) to 0.2 seconds. That is, the control circuit  71  performs the drive control of the motor  3  such that the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  in 0.2 seconds after the motor  3  is started to drive. 
     Subsequently, the control circuit  71  sets the light part  8  to the light-on state (S 207 ) and starts driving the motor  3  (S 209 ). In the main body control according to the first modification, the processing of S 210 :YES and from S 211 :NO to S 213  to be performed after the motor  3  is started in S 209  when the dust collector  100  is not connected to the main body  2  is the same as the processing of S 109 :YES and from S 110 :NO to S 112  of the flowchart of  FIG. 7  in the main body control according to the above embodiment. 
     On the other hand, when determining in S 204  that the dust collector  100  is connected to the main body  2  (S 204 :YES), the control circuit  71  sets the target-rotation-speed arrival time period of the motor  3  to one second (S 208 ). That is, the control circuit  71  performs the drive control of the motor  3  such that the rotation speed of the motor  3  reaches the prescribed target rotation speed N 1  in one second after the motor  3  is started to drive. 
     After setting the target-rotation-speed arrival time period to one second in S 208 , the control circuit  71  starts driving the motor  3  (S 209 ). In the main body control according to the first modification, the processing of S 210 :YES and from S 211 :YES to S 216  to be performed after the motor  3  is started in S 209  when the dust collector  100  is connected to the main body  2  is the same as the processing of S 109 :YES and from S 110 :YES to S 115  of the flowchart of  FIG. 7  in the main body control according to the above embodiment. 
     Next, a relationship between the driving of the motor  3  and various signals in the case where the dust collector  100  is connected to the main body  2  in the above-described main body control performed by the control circuit  71  will be described with reference to a timing chart of  FIG. 11 . 
     When the starting operation is performed for the trigger switch  12  at a timing t 21 , the motor  3  is started to drive. At the timing t 21 , the control circuit  71  performs: output of the dust-collector drive signal; detection of the connection determination voltage (substantially 4 V), the connection detection based on the detected connection determination voltage; and setting of the target-rotation-speed arrival time period (one second) of the motor  3 . This corresponds to the processing from S 201 :YES to S 204 :YES, S 208 , and S 209  in the flowchart of  FIG. 10 . At this time, because the dust collector  100  is connected, the LED light of the light part  8  is kept turned off. 
     For facilitating description, in this timing chart as well, the following are all assumed to be performed at the timing t 21 : the output of the dust-collector drive signal; the detection of the connection determination voltage; the connection detection; the setting of the target-rotation-speed arrival time period; and the start of the motor  3 . Actually, however, the output of the dust-collector drive signal, the detection of the connection determination voltage, the connection detection, the setting of the target-rotation-speed arrival time period, and the start of the motor  3  are performed sequentially in this order in a very short period of time. 
     In the main body control according to the first modification, the rotation speed of the motor  3  reaches the target rotation speed N 1  at a timing t 22  after a lapse of one second from the timing t 21  based on the target-rotation-speed arrival time period set in S 208  of  FIG. 10 . That is, in the main body control according to the first modification, the arrival required time period (time period from the time when the starting operation is performed for the trigger switch  12  to the time when the rotation speed of the motor  3  reaches the target rotation speed N 1 ) when the dust collector  100  is connected to the main body  2  is a time period T 3  (a time period between the timing t 21  and timing t 22 ). 
     In the main body control according to the first modification, in the case where the dust collector  100  is not connected to the main body  2 , the target-rotation-speed arrival time period of the motor  3  is set to 0.2 seconds (S 206  in  FIG. 10 ). Hence, the time period T 3  which is the arrival required time period when the dust collector  100  is connected is longer than the arrival required time period when the dust collector  100  is not connected. That is, also in the main body control according to the first modification, the rotation speed of the motor  3  is configured to reach the target rotation speed N 1  at a later timing when the dust collector  100  is connected than when the dust collector  100  is not connected. In the first modification, the arrival required time period when the dust collector  100  is not connected is an example of the “first time period” in the present invention, and the time period T 3  is an example of the “second time period” in the present invention. 
     After the rotation speed reaches the prescribed target rotation speed N 1  at the timing t 22 , the control circuit  71  continues driving the motor  3  with the rotation speed thereof maintained at the target rotation speed N 1  through the constant rotation speed control. 
     When the starting operation for the trigger switch  12  is released thereafter at a timing t 23 , the driving of the motor  3  is halted. This corresponds to the processing of S 210 :YES, S 211 :YES, and S 214  in the flowchart of  FIG. 10 . 
     Even after the driving of the motor  3  is halted at the timing t 23 , the dust-collector drive signal is kept being outputted for 10 seconds (corresponding to the stop delay processing of S 215 :NO in the flowchart of  FIG. 10 ). Subsequently, the output of the dust-collector drive signal is halted at a timing t 24  after a lapse of 10 seconds from the timing t 23  when the driving of the motor  3  was stopped. This corresponds to the processing from S 215 : YES to S 216  in the flowchart of  FIG. 10 . In response to the halt of the output of the dust-collector drive signal, the output of the connection determination voltage from the node  27 B is also halted at the timing t 24 . 
     As described above, in the main body control according to the first modification as well, the time period T 3  which is the arrival required time period from the time when the starting operation is performed for the trigger switch  12  to the time when the rotation speed of the motor  3  reaches the target rotation speed N 1  when the dust collector  100  is connected is set longer than the arrival required time period when the dust collector  100  is not connected. With this structure, the timing at which the connected dust collector  100  is sufficiently driven can be brought closer to the timing at which the rotation speed of the motor  3  reaches the target rotation speed N 1 . Thus, the driving of the motor  3  is less likely to be started before the dust collector  100  is sufficiently driven. 
     In addition, the same technical advantages as the main body control according to the above embodiment can be obtained. 
     The work tool according to the present invention is not limited to the embodiment described above, but many modifications and variations may be made therein without departing from the scope of the appended claims. 
     For example, in each of the main body control according to the above embodiment and the first modification, a maximum rotation speed of the motor  3  is set to the same value, i.e., the target rotation speed N 1 , for both of the cases where the dust collector  100  is connected and the dust collector  100  is not connected. However, the maximum rotation speed of the motor  3  may be made different between the case where the dust collector  100  is connected and the case where the dust collector  100  is not connected. 
       FIG. 12  is a timing chart illustrating a relationship between a control performed by the control circuit  71  and the driving of the motor  3  when the dust collector  100  is connected to the main body  2  in the main body control according to a second modification to the embodiment. 
     As illustrated in  FIG. 12 , in the main body control according to the second modification, the maximum rotation speed of the motor  3  when the dust collector  100  is connected is set to a target rotation speed N 2  lower than the target rotation speed N 1 . That is, the maximum rotation speed of the motor  3  when the dust collector  100  is connected may be set lower than the maximum rotation speed of the motor  3  when the dust collector  100  is not connected. The target rotation speed N 1  according to the second modification is an example of a “first rotation speed” in the present invention, and the target rotation speed N 2  is an example of a “second rotation speed” in the present invention. 
     With this configuration, the amount of dust or the like generated by a work performed by the end bit  14  can be reduced. This configuration is particularly effective in a case where a large amount of dust is likely to be generated during a work; or in a configuration where the dust collector  100  as the attachment device is connected to the main body  2 . In other words, even when dust collecting performance of the dust collector  100  is kept constant, dust collection efficiency can be increased by the reduction in the amount of the generated dust. 
       FIG. 12  illustrates a case where the main body control according to the second modification is combined with the main body control of the above embodiment. Note that the main body control according to the second modification may also be combined with the main body control according to the first modification. 
     In the above embodiment and the first modification, the target rotation speed is one predetermined value, but need not to be limited thereto. For example, there may be provided a dial for changing the target rotation speed. In this case, a prescribed target rotation speed can be set according to an operation amount (position) of the dial. Still further, the target rotation speed corresponding to the operation amount of the dial may be made different depending on whether the dust collector  100  is connected or not. For example, a target rotation speed corresponding to a predetermined dial operation amount when the dust collector  100  is connected may be set lower than a target rotation speed corresponding to a predetermined operation amount when the dust collector  100  is not connected. In this case, the maximum rotation speed of the motor  3  when the dust collector is connected can be lower than the maximum rotation speed of the motor  3  when the dust collector  100  is not connected. Accordingly, the similar technical advantages as the above second modification can be obtained. 
     Alternatively, for example, in the case where the dust collector  100  is not connected, the target rotation speed may be made proportional to the dial operation amount such that the target rotation speed becomes maximum when the dial operation amount is maximum; however, when the dust collector  100  is connected, the target rotation speed may not be increased proportionally but made constant in a case where the dial operation amount is equal to or larger than a predetermined amount. In this case, as long as the dial operation amount is equal to or larger than the predetermined amount, the maximum rotation speed of the motor  3  when the dust collector  100  is connected can be made lower than the maximum rotation speed of the motor  3  when the dust collector  100  is not connected. Accordingly, the similar technical advantages as the above second modification can be obtained. 
     Further, the switching mechanism  12 A of the above embodiment is configured to output the start-up signal of a fixed value to the control circuit  71  (control substrate part  7 ) irrespective of an amount by which the trigger switch  12  is pulled in the starting operation. However, the present invention is not limited to this configuration. For example, the start-up signal of a value corresponding to the amount by which the trigger switch  12  is puled may be outputted to the control circuit  71 . In this case, the control circuit  71  may set a target rotation speed according to the value of the start-up signal. 
     Further, in the above embodiment, the light part  8  as the assisting means is configured to be placed in the light-off state (non-active state) when the dust collector  100  is connected, while placed in the light-on state (active state) when the dust collector  100  is not connected. In addition to the lighting means like the light part  8 , a display that can display information on the main body  2  may be available as the assisting means that is deactivated when the attachment device is connected but activated when the attachment device is not connected. 
     Further, contrary to the depicted embodiment, the assisting means may be activated when the attachment device is connected, but may be deactivated when the attachment device is not connected. As the assisting means as such, an indication lamp or a display may be provided in the main body of the work tool in order to allow an operator to be notified of an operating state of the attachment device and/or necessity of maintenance (for example, if the attachment device is a dust collector, such information that a dust-collection case is full, or whether a filter should be replaced or not). 
     Further, in the above embodiment, the light part  8  as the assisting means is put in the light-off state (non-active state) when the dust collector  100  is connected, while being put in the light-on state (active state) when the dust collector  100  is not connected; that is, power to be supplied to the assisting means is rendered ON/OFF depending on whether the connection/non-connection of the dust collector  100 . However, the present invention is not limited to this. For example, power to be supplied to the assisting means may be changed depending on the connection/non-connection of the dust collector  100 . 
     Further, in the above embodiment, the light part  8  (lighting means) is provided only at the main body  2  and is configured to be put in the light-off state (non-active state) when the dust collector  100  is connected. However, the lighting means may be provided not only at the main body  2  but also at the dust collector  100  connectable to the main body  2 . In this case, when the dust collector  100  is connected to the main body  2 , the lighting means provided at the dust collector  100  may be placed in the light-on state (active state) but the light part  8  provided at the main body  2  may be placed in the light-off state (non-active state). On the other hand, only the light part  8  of the main body  2  may be placed in the light-on state (active state) when the dust collector  100  is not connected. 
     In the present embodiment, in the case where the hammer drill  1  is used alone, the LED light of the light part  8  is configured to be automatically tuned on in conjunction with the starting operation for the trigger switch  12 . However, the operator may be able to select, as appropriate, whether the light part  8  should be turned on or off. 
     Further, in the present embodiment, the main body control (such as the control over the motor  3  and the light part  8 ) is configured to be automatically changed depending on the connection/non-connection of the dust collector  100 . However, the operator may be able to select, as appropriate, whether the control for the hammer drill  1  should be changed or not. That is, even when the dust collector  100  is connected, the operator may be able to select that the behavior of the hammer drill  1  when used alone should be maintained. Advantageously, in this case as well, the driving of the dust collector  100  may be started in conjunction with the trigger switch  12  of the hammer drill  1 . 
     Note that, the “turn-off” state of the lighting means in the present invention not only includes a case where the lighting means is completely turned OFF as in the present embodiment, but also includes a case where the lighting means is not completely turned OFF but is slightly lit by receiving a very small amount of power. Further, the “turned-on” state of the lighting means not only includes a case where the lighting means is illuminated as in the above embodiment but also includes a case where the lighting means flashes. 
     Further, in the above embodiment, the control circuit  71  is configured to stop driving the motor  3  when the acceleration detected by the acceleration sensor  23  exceeds the predetermined acceleration threshold value. Further, the control circuit  71  may be configured to change the acceleration threshold value depending on the presence/absence of the connection of the dust collector  100 . With this configuration, the acceleration threshold value can be appropriately set based on whether the hammer drill  1  is used alone or used with the dust collector  100  connected to the main body  2 . The main body  2  can be reliably suppressed from being applied with an excessive load. 
     In the present embodiment, the battery  15  (DC power supply) is used as a power source of the hammer drill  1 . However, the hammer drill  1  may receive power from a commercial power source (AC power supply), instead of the battery  15 . 
     Further, the attachment device configured to be detachably connected to the main body of the work tool according to the present invention is not limited to the dust collector as described in the present embodiment for sucking the dust and the like generated from a work piece. For example, as the attachment device, a blower having a blast function to blow off dust or the like generated from a work piece may be connected to the main body of the work tool. Alternatively, a dust collector having a blast function may be connected to the main body of the work tool, as the attachment device. 
     While the hammer drill  1  according to the present embodiment can impart an impacting force and a rotational force to the end bit  14 , the hammer drill  1  may impart only the impacting force or only the rotational force. Further, the end bit  14  may be a driver bit for fastening a screw, or may be a drill bit for drilling or chipping concrete or a stone material. 
     In the present embodiment, the hammer drill  1  is employed as an example of the work tool. However, the present invention may be applied to a motor-driven work tool other than a hammer drill, for example, to a drilling tool such as an electric hammer, an electric drill, a vibration drill, or a driver drill. 
     REFERENCE SIGNS LIST 
     
         
           1  . . . hammer drill 
           2  . . . main body 
           3  . . . motor 
           4  . . . drive-transmission part 
           5  . . . impact mechanism part 
           6  . . . reciprocating-movement conversion part 
           7  . . . control substrate part 
           8  . . . light part 
           9  . . . power-supply part 
           12  . . . trigger switch 
           12 A . . . switching mechanism 
           15  . . . battery 
           21 A . . . battery-connecting terminal part 
           22 A . . . switching circuit 
           23  . . . acceleration sensor 
           27  . . . second signal line 
           91 A . . . main-body-side positive terminal 
           91 B . . . main-body-side negative terminal 
           91 C . . . main-body-side signal terminal 
           100  . . . dust collector 
           112  . . . collector motor 
           116 A . . . collector-side positive terminal 
           116 B . . . collector-side negative terminal 
           116 C . . . collector-side signal terminal