Patent ID: 12194596

DESCRIPTION OF EMBODIMENTS

In one or more embodiment(s), a tool may include a first accessory, a second accessory, a first attachment portion configured to allow the first accessory to be detachably attached thereto, a second attachment portion configured to allow the second accessory to be detachably attached thereto, a first intermediate member configured to be displaced from a first non-attachment position to a first attachment position by the attachment of the first accessory to the first attachment portion, a second intermediate member configured to be displaced from a second non-attachment position to a second attachment position by the attachment of the second accessory to the second attachment portion, and a single sensor configured to detect a specific state in which the first intermediate member is located at the first attachment position and the second intermediate member is located at the second attachment position.

According to this tool, the tool detects that the first intermediate member is located at the first attachment position and the second intermediate member is located at the second attachment position using the single sensor. The first intermediate member located at the first attachment position means that the first accessory is attached, and the second intermediate member located at the second attachment position means that the second accessory is attached, and therefore the attachment of the two types of accessories can be detected using the single sensor.

In one or more embodiment(s), the single sensor may be a photoelectric sensor including a light emitter and a light receiver, or an ultrasonic sensor. The first intermediate member may be configured to be displaced between a position of blocking light emitted from the light emitter or an ultrasonic wave emitted from the ultrasonic sensor and a position of not blocking the light or the ultrasonic wave due to the attachment or no attachment of the first accessory to the first attachment portion. The second intermediate member may be configured to be displaced between a position of blocking the light or the ultrasonic wave and a position of not blocking the light or the ultrasonic wave due to the attachment or no attachment of the second accessory to the second attachment portion. According to this configuration, the attachment of the two types of accessories can be easily detected using the single photoelectric sensor or the single ultrasonic sensor.

In one or more embodiment(s), the single sensor may be a reflection-type photosensor. In one or more embodiment(s), the single sensor may be a transmission-type photosensor.

In one or more embodiment(s), the tool may include an electric motor, and a controller configured to control driving of the electric motor. The controller may permit the electric motor to be driven when the single sensor detects the specific state and prohibit the electric motor from being driven when the single sensor does not detect the specific state.

In one or more embodiment(s), the tool may be a grinder including a tool accessory configured to be rotated by the electric motor. The first accessory may be a side grip, and the second accessory may be a cover that partially covers the tool accessory.

In one or more embodiment(s), the first attachment portion may include at least two side grip attachment portions for selectively attaching the side grip. The first intermediate member may be a single member provided in common for the at least two side grip attachment portions and configured to be rotatable about a rotational axis of the electric motor. The at least two side grip attachment portions may be located at positions spaced apart from each other in a circumferential direction around the rotational axis, respectively. The first intermediate member may include at least one pressed portion configured to, when the side grip is attached to one side grip attachment portion arbitrarily selected from the at least two side grip attachment portions, be directly or indirectly pressed by the side grip, and the first intermediate member may be rotated about the rotational axis when the at least one pressed portion is pressed. According to this configuration, regardless of which is selected from the at least two side grip attachment portions to attach the side grip, this attachment can be detected. In addition, the single first intermediate member is used in common for the at least two side grip attachment portions, and therefore the number of components can be reduced.

In one or more embodiment(s), the first intermediate member may have an annular shape or a partially annular shape. According to this configuration, the first intermediate member is shaped to correspond to the layout of the at least two side grip attachment portions, and therefore the single first intermediate member can be used in common for the at least two side grip attachment portions with a simple structure.

In one or more embodiment(s), the at least one pressed portion may protrude radially outward from a first intermediate member main body. The at least one pressed portion may be provided at at least two positions respectively corresponding to positions of the at least two side grip attachment portions, respectively. According to this configuration, the first intermediate member can be easily rotated.

In one or more embodiment(s), the at least one pressed portion may include a pressed surface angled with respect to a longitudinal direction of the side grip in such a manner that the first intermediate member is displaced in a direction different from the longitudinal direction of the side grip. The longitudinal direction of the side grip is a longitudinal direction of the side grip when the side grip is attached to the one side grip attachment portion. According to this configuration, the first intermediate member can be easily rotated.

In one or more embodiment(s), the first intermediate member main body may include a first through-hole having a circular-arc shape centered at the rotational axis. The first intermediate member main body may be attached rotatably along the circular-arc shape using a screw via the first through-hole. According to this configuration, the first intermediate member can be held rotatably with a simple structure.

In one or more embodiment(s), the first intermediate member may include a second through-hole. The light or the ultrasonic wave may pass through the second through-hole when the first intermediate member is located at the position of not blocking the light or the ultrasonic wave. According to this configuration, the first intermediate member can have a compact size.

In one or more embodiment(s), the second intermediate member may be configured to be linearly moved by being directly or indirectly pressed by the cover when the cover is attached to the second attachment portion. According to this configuration, the tool does not have to include a direction conversion mechanism by being designed in such a manner that the attachment direction of the cover matches a linear motion direction of the second intermediate member, thereby allowing the second intermediate member to be displaced with a simple structure.

In one or more embodiment(s), the second intermediate member may include a third through-hole in the form of an elongated hole having a longitudinal direction extending along a direction in which the second intermediate member is linearly moved. The second intermediate member may be attached linearly movably along the elongated hole using a screw via the third through-hole. According to this configuration, the second intermediate member can be held linearly movably with a simple structure.

In one or more embodiment(s), the tool may include a single holding member that holds the first intermediate member and the second intermediate member. According to this configuration, mounting each of the first intermediate member and the second intermediate member on the holding member automatically determines the relative positions of the first intermediate member and the second intermediate member. In other words, the relative positions of the first intermediate member and the second intermediate member do not have to be adjusted when the tool is assembled.

In the following description, the embodiments of the present invention will be described in further detail with reference to the drawings. First, a first embodiment of the present invention will be described with reference toFIGS.1to14. In the embodiments that will be described below, a handheld-type electric disk grinder (hereinafter simply referred to as a grinder)10will be cited as an example of the tool.

As illustrated inFIGS.1and2, the grinder10is configured to rotationally drive a generally disk-like tool accessory28mounted around a spindle25. The spindle25is rotated by a rotational driving force provided from an electric motor31as the prime mover. A grinding stone, a rubber pad, a brush, a blade, and the like are prepared as the tool accessory28mountable on the grinder10. A user selects the appropriate tool accessory28according to desired processing work and mounts it on the grinder10. According to the grinder10, processing work such as grinding, polishing, and cutting can be performed on a processing target material according to the type of the tool accessory28.

In the following description, a direction in which a rotational axis AX1of the electric motor31(i.e., a motor shaft32) extends is defined to be a front-rear direction of the grinder10. One side in the front-rear direction on which the tool accessory28is located is defined to be a front side, and the opposite side therefrom is defined to be a rear side. Further, a direction in which a rotational axis AX2of the spindle25(i.e., a rotational axis of the tool accessory28) extends is defined to be a vertical direction of the grinder10. One side in the vertical direction on which the tool accessory28is located is defined to be a lower side, and the opposite side therefrom is defined to be an upper side. Further, a direction perpendicular to the vertical direction and the front-rear direction is defined to be a left-right direction of the grinder10. A right side in the left-right direction when the front side is viewed from the rear side is defined to be a right side of the grinder10, and the opposite side therefrom is defined to be a left side of the grinder10.

As illustrated inFIGS.1and2, the grinder10includes a gear housing20, a motor housing30, and a handle housing40. The electric motor31is contained in the motor housing30, which is located between the gear housing20and the handle housing40in the front-rear direction, i.e., the longitudinal direction of the grinder10. The electric motor31is configured to be driven by electric power supplied from outside (alternating-current power supplied from an AC power source in the present embodiment, but may be direct-current power supplied from a battery). Further, a controller33is contained between the electric motor31and a switch41in the front-rear direction in the handle housing40. The controller33receives the electric power supplied from outside and supplies this electric power to the electric motor31and a sensor80, which will be described below. The controller33controls the driving of the electric motor31by controlling the electric power supplied to the electric motor31.

A mechanism for transmitting the rotational driving force of the electric motor31to the tool accessory28is contained in the gear housing20. More specifically, a small bevel gear23, a large bevel gear24, and the spindle25are contained in the gear housing20. The small bevel gear23is fixed around the motor shaft32at the front end portion of the motor shaft32of the electric motor31. The spindle25is supported rotatably about the rotational axis AX2by bearings disposed so as to be vertically spaced apart from each other. The rotational axis AX2intersects with (more specifically, intersects perpendicularly to) the rotational axis AX1of the electric motor31. The large bevel gear24is fixed around the spindle25on the upper side of the spindle25, and is meshed with the small bevel gear23. The gear housing20includes a second attachment portion22at the lower edge portion thereof. The second attachment portion22is used to detachably attach a cover300. The second attachment portion22has a vertically extending cylindrical shape. The spindle25extends vertically in the gear housing20, and extends out of the gear housing20(more specifically, the second attachment portion22) on the lower side.

An inner flange26is attached around the spindle25at the lower end portion of the spindle25extending out of the gear housing20. A male screw portion is formed on a lower portion of the spindle25with respect to the inner flange26, and a lock nut27is attached to this male screw portion. The position of the tool accessory28relative to the spindle25is fixed by interposing the tool accessory28between the inner flange26and the lock nut27and tightening the lock nut27.

The handle housing40is a portion to be held by the user with one of his/her hands when the grinder10is in use. The handle housing40has a hollow circular cylindrical shape extending generally in the front-rear direction. The switch41for driving the electric motor31is contained inside the handle housing40. An operation member50is provided under the handle housing40. The operation member50is configured to be displaceable between an OFF position of bringing the switch41into an OFF state and an ON position of bringing the switch41into an ON state.FIGS.1and2illustrate the operation member50located at the OFF position. A lock-off switch57is provided near the front end of the operation member50in the front-rear direction. The lock-off switch57is used to engage the operation member50at the OFF position, thereby prohibiting the operation member50from being displaced to the ON position. When the operation member50is operated from the OFF position to the ON position by the user, the switch41detects that and transmits a detection signal to the controller33. Upon receiving this detection signal, the controller33supplies the electric power to the electric motor31, thereby driving the electric motor31. When the electric motor31is driven, the rotation of the motor shaft32is transmitted to the spindle25while being slowed down via the small bevel gear23and the large bevel bear24. At this time, the direction of the rotational motion is converted from the direction around the motor shaft32into the direction around the rotational axis AX2of the spindle25. According to this mechanism, the spindle25is rotated about the rotational axis AX2in response to the rotation of the motor shaft32, and the tool accessory28fixed by the inner flange26and the lock nut27is rotated together with the spindle25as a result thereof.

As illustrated inFIG.1, the grinder10further includes a side handle200and the cover300as the accessories thereof. The side handle200is prepared to be held by the user with the opposite hand from his/her hand holding the handle housing40. The user can further stably hold the grinder10by using the side handle200. The side handle200includes a grip portion210to be held by the user, and an attachment portion220to be attached to the gear housing20. The attachment portion220has a circular columnar shape extending in the longitudinal direction of the side handle200, and extends out of one end of the grip portion210in the longitudinal direction of the side handle200. A male screw is formed on the outer peripheral surface of the attachment portion220.

As illustrated inFIG.9, the gear housing20includes three first attachment portions29ato29cfor detachably attaching the side handle200. The first attachment portions29ato29care disposed at positions spaced apart from each other in the circumferential direction around the rotational axis AX1. More specifically, the first attachment portion29ais formed on the left surface of the gear housing20, the first attachment portion29bis formed on the upper surface of the gear housing20, and the first attachment portion29cis formed on the right surface of the gear housing20. The three first attachment portions29ato29care provided at positions rotational symmetric with respect to the rotational axis AX1, respectively. Each of the first attachment portions29ato29cis provided in the form of a through-hole that establishes communication between the inside and the outside of the gear housing20. A female screw threadedly engageable with the male screw of the attachment portion220is formed on the inner surface forming this through-hole.

The side handle200can be attached to the gear housing20by screwing the attachment portion220of the side handle200into selected one from the three first attachment portions29ato29c. The user can arbitrarily select the attachment portion of the side handle200from the first attachment portions29ato29caccording to the type of the work intended to perform using the grinder10or according to whether the user is right-handed or left-handed. The three first attachment portions29ato29care provided in the present embodiment, but the number of first attachment portions is not especially limited and may be any number equal to or greater than 1. For example, the grinder10may include only two first attachment portions29aand29c.

As illustrated inFIG.1, the cover300includes a cover main body310to cover a part of the tool accessory28therewith, and an attachment portion320to be attached to the second attachment portion22. The cover main body310covers an approximately rear half portion of the tool accessory28. The cover main body310covers the upper surface, the lower surface, and the circumferential surface between the upper surface and the lower surface of the tool accessory28in the present embodiment, but may cover only the upper surface and the circumferential surface depending on the type of the tool accessory28in use. The attachment portion320has a generally annular shape with an opening, and extends upward from the upper surface of the cover main body310. The attachment portion320includes opposing two flanges at two distal ends in the circumferential direction, although they are not illustrated because the structure of the attachment portion320is well known. A bolt is inserted into a screw hole formed at each of the flanges and is tightened in a state that the attachment portion320is disposed so as to surround the second attachment portion22of the gear housing20, by which the radius of the annular shape of the attachment portion320reduces and the attachment portion320is fixed to the second attachment portion22.

The above-described grinder10is configured to permit the electric motor31to be driven only in a state that the side handle200is attached to any of the first attachment portions29ato29cof the gear housing20and the cover300is also attached to the second attachment portion22of the gear housing20. In a state that at least one of the side handle200and the cover300is not attached, the controller33prohibits the electric motor31from being driven even when the user operates the operation member50to the ON position and the detection signal is transmitted from the switch41to the controller33. The state in which both the side handle200and the cover300are attached is detected by the single sensor80, which will be described below, and is output from the sensor80to the controller33via a signal line (not illustrated). In the following description, a configuration for this detection will be described in detail with reference to the drawings.

As illustrated inFIGS.1and2, the grinder10further includes a first intermediate member60, a second intermediate member70, a holding member140, and the sensor80. First, the first intermediate member60, the second intermediate member70, the holding member140, and the sensor80will be described in outline.

The first intermediate member60is configured to be pressed and displaced by the attachment portion220of the side handle200by the attachment of the side handle200to any of the first attachment portions29ato29c. The first intermediate member60is rotated by a predetermined angle about the rotational axis AX1as such a displacement operation in the present embodiment. The position of the first intermediate member60when the side handle200is attached to none of the first attachment portions29ato29cof the gear housing20will be referred to as a first non-attachment position (refer toFIGS.4and9). The position of the first intermediate member60when the side handle200is attached to any of the first attachment portions29ato29cwill be referred to as a first attachment position (refer toFIGS.3,10, and11). The first intermediate member60is a generally annular member, and is disposed inside the gear housing20so as to surround the motor shaft32on the front side with respect to the electric motor31.

The second intermediate member70is configured to be pressed and displaced by the attachment portion320of the cover300by the attachment of the cover300to the second attachment portion22. The second intermediate member70is linearly moved upward as such a displacement operation in the present embodiment. The position of the second intermediate member70when the cover300is not attached to the second attachment portion22of the gear housing20will be referred to as a second non-attachment position (refer toFIGS.4,9, and10). The position of the second intermediate member70when the cover300is attached to the second attachment portion22will be referred to as a second attachment position (refer toFIGS.5and16). The second intermediate member70is disposed between the motor shaft32and the tool accessory28on the front side with respect to the first intermediate member60.

The holding member140is disposed on the front side with respect to the first intermediate member60, and holds the first intermediate member60and the second intermediate member70together.

The sensor80detects a state in which the first intermediate member60is located at the first attachment position and the second intermediate member70is located at the second attachment position. In the present embodiment, the sensor80is a photoelectric sensor.

In the following description, the first intermediate member60, the second intermediate member70, the holding member140, and the sensor80will be described in detail. First, the first intermediate member60will be described. As illustrated inFIG.5, the first intermediate member60is a single member, and is provided in common for the first attachment portions29ato29c. The first intermediate member60includes a first intermediate member main body61. The first intermediate member main body61has an annular shape centered at the rotational axis AX1of the electric motor31in the present embodiment. However, the first intermediate member60may have a partially annular shape (i.e., an unclosed annular shape). A through-hole is formed at the central portion of the first intermediate member main body61. The motor shaft32extends through this through-hole.

The first intermediate member60further includes three pressed portions62ato62cand a second through-hole64. The three pressed portions62ato62care disposed so as to be circumferentially spaced apart from each other. The pressed portion62ais a portion pressed by the side handle200(more specifically, the distal end of the attachment portion220) when the side handle200is attached to the first attachment portion29aof the gear housing20. Similarly, the pressed portion62bis a portion pressed by the side handle200when the side handle200is attached to the first attachment portion29b, and the pressed portion62cis a portion pressed by the side handle200when the side handle200is attached to the first attachment portion29c. Therefore, the pressed portions62ato62care disposed at angular positions corresponding to the angular positions of the first attachment portions29ato29c, respectively (refer toFIG.14). Each of the pressed portions62ato62cprotrudes radially outward from the first intermediate member main body61.

As described above, the first intermediate member60is configured to be rotated about the rotational axis AX1when any of the pressed portions62ato62cis pressed by the side handle200. A comparison betweenFIG.9andFIG.10makes it understandable that, due to the attachment of the side handle200to the first attachment portion29c, the pressed portion62cis pressed by the side handle200, and the first intermediate member60is rotated in the counterclockwise direction from the position illustrated inFIG.9to the position illustrated inFIG.10.

As illustrated inFIGS.5and9, the pressed portion62aincludes a pressed surface63aangled with respect to the longitudinal direction of the side handle200when the side handle200is attached to the first attachment portion29a(i.e., the attachment direction of the side handle200). Similarly, the pressed portion62bincludes a pressed surface63bangled with respect to the longitudinal direction of the side handle200when the side handle200is attached to the first attachment portion29b. Similarly, the pressed portion62cincludes a pressed surface63cangled with respect to the longitudinal direction of the side handle200when the side handle200is attached to the first attachment portion29c. The pressed surfaces63ato63care angled at approximately 45 degrees with respect to the corresponding longitudinal direction of the side handle200(refer toFIG.9). This angle can be set to any angle so as to allow the first intermediate member60to be displaced in a direction different from the longitudinal direction of the side handle200. In an alternative embodiment, this angle may be set within a range of 30 degrees or larger and 60 degrees or smaller. According to the pressed surfaces63ato63cangled in this manner, the first intermediate member60can be easily rotated.

The second through-hole64extends through the first intermediate member60in the front-rear direction. When the first intermediate member60is located at the first non-attachment position illustrated inFIG.9, the second through-hole64is located at an angular position offset from the lowermost portion of the first intermediate member60slightly to the left side and the upper side (i.e., a position at which the second through-hole64does not overlap a blocking portion73of the second intermediate member70, which will be described below, as viewed in the front-rear direction). On the other hand, when the first intermediate member60is located at the first attachment position illustrated inFIG.10, the second through-hole64is located at an angular position of the lowermost portion of the first intermediate member60(i.e., a position at which the second through-hole64overlaps the blocking portion73of the second intermediate member70, which will be described below, as viewed in the front-rear direction).

As illustrated inFIG.5, the first intermediate member main body61includes first through-holes65and66. Each of the first through-holes65and66has a circular-arc shape centered at the rotational axis AX1. The first through-holes65and66are disposed at positions rotational symmetric by 180 degrees with respect to the rotational axis AX1. The first intermediate member60is attached to the holding member140using screws via these first through-holes65and66. More specifically, bolts91are inserted in the first through-holes65and66as illustrated inFIGS.9to11. These bolts91are threadedly engaged with screw holes143aand144aof the holding member140, which will be described below. Actually, a sensor board holding member85(refer toFIG.8), which will be described below, is disposed between the first intermediate member60and the heads of the bolts91, and the bolts91are disposed so as to extend through through-holes87and88of the sensor board holding member85and the first through-holes65and66, respectively, although this is not illustrated inFIGS.9to11. Due to a predetermined clearance secured between the holding member140and/or the sensor board holding member85and the first intermediate member60, the first intermediate member60is held by the holding member140rotatably along the circular-arc shapes of the first through-holes65and66. According to this configuration, the first intermediate member60can be held with a simple structure.

The first intermediate member60further includes a protrusion67. The protrusion67extends forward from the front surface of the first intermediate member main body61. This protrusion67is used to bias the first intermediate member60toward the first non-attachment position (refer toFIGS.4and9) by a spring68(refer toFIG.7), which will be described below.

Next, the second intermediate member70will be described. As illustrated inFIG.6, the second intermediate member70includes a base71, a pressed portion72, a blocking portion73, support portions74and75, and a spring seat78. The base71is a portion shaped like a flat plate which has a longitudinal direction extending along the front-rear direction and lies perpendicularly to the vertical direction. The pressed portion72is a portion pressed upward by the attachment portion320of the cover300when the cover300is attached to the second attachment portion22, and is located at the front edge of the second intermediate member70. The pressed portion72is shaped like a flat plate lying in parallel with the base71. A stepped portion is formed between the base71and the pressed portion72. The displacement amount of the second intermediate member70when the cover300is attached can be reduced due to this stepped portion. More specifically, when the cover300is attached, the second intermediate member70is not displaced since the attachment portion320of the cover300is in a state of being raised to the same position as the base71until the attachment portion320is brought into a state of abutting against the pressed portion72, and therefore the displacement amount of the second intermediate member70is reduced by an amount corresponding the step compared to a configuration in which the pressed portion72is located at the same vertical position as the base71. This can lead to a reduction in a space for the displacement of the second intermediate member70. In other words, this can cut down an increase in the vertical size of the grinder10.

The blocking portion73is a portion that blocks light emitted from the sensor80when the second intermediate member70is located at the second attachment position. The blocking portion73is located at the rear edge of the second intermediate member70, and extends upward from the rear edge of the base71. The blocking portion73is shaped like a flat plate extending perpendicularly to the front-rear direction.

The support portions74and75are disposed opposite from each other in the left-right direction on the front side with respect to the blocking portion73near the blocking portion73. The support portions74and75have generally L-like shapes extending from the base71in directions away from each other in the left-right direction, and then bent and extending upward after that. Third through-holes76and77are formed on the support portions74and75, respectively. The third through-holes76and77extend through the support portions74and75in the front-rear direction, respectively. The third through-holes76and77are each in the form of an elongated hole having a longitudinal direction extending along the vertical direction (i.e., a direction in which the second intermediate member70is linearly moved when being pressed by the cover300). The second intermediate member70is attached to the holding member140using screws via these third through-holes76and77. More specifically, bolts92are inserted in the third through-holes76and77as illustrated inFIGS.9to11. These bolts92are threadedly engaged with screw holes145aand146aof the holding member140, which will be described below. Due to predetermined clearances secured between the heads of the bolts92and the support portions74and75, respectively, the second intermediate member70is held by the holding member140linearly movably along the third through-holes76and77. According to this configuration, the second intermediate member70can be held with a simple structure.

The spring seat78is provided so as to protrude upward from the base71. A spring79(refer toFIG.4) is held between the spring seat78and a spring seat148of the holding member140(refer toFIG.7). The spring79biases the second intermediate member70toward the second non-attachment position (refer toFIGS.4,9, and10).

Next, the holding member140will be described. As illustrated inFIG.7, the holding member140includes an annular portion141, a hollow circular cylindrical portion142, protrusion portions143and144, protrusion portions145and146, the spring seat148, and a spring housing portion149. The annular portion141has a disk-like shape centered at the rotational axis AX1of the electric motor31, and a through-hole is formed at the center thereof. A cutout147is formed on the lower side of the annular portion141to secure the space for the displacement of the second intermediate member70.

The hollow circular cylindrical portion142has a hollow circular cylindrical shape extending rearward from the annular portion141. The diameter of the hollow circular cylindrical portion142is smaller than the diameter of the annular portion141. The spring housing portion149is formed at the upper side of the hollow circular cylindrical portion142adjacently to the hollow circular cylindrical portion142. The spring housing portion149is formed to have a circular-arc shape centered at the rotational axis AX1. The spring68is housed in the spring housing portion149. The spring68is extensible and compressible along the circular-arc shape of the spring housing portion149. The rear side of the spring housing portion149is opened, and the protrusion67of the first intermediate member60is inserted in the spring housing portion149via this opening. One end of the spring68is supported on the inner surface of the spring housing portion149(a flat surface located at one end portion of the circular-arc shape), and the other end of the spring68is engaged with the protrusion67. Due to this configuration, the first intermediate member60is biased in the clockwise direction (i.e., toward the first non-attachment position).

The protrusion portions143and144are disposed so as to be spaced apart from each other in the left-right direction. The protrusion portions143and144extend rearward from the annular portion141at approximately vertically central positions of the annular portion141. The protrusion portions143and144include the screw holes143aand144ahaving female screws formed thereon, respectively. The screw holes143aand144aextend forward from the rear end surfaces of the protrusion portions143and144, respectively. The bolts91are threadedly engaged with the screw holes143aand144ato mount the first intermediate member60to the holding member140in the above-described manner (refer toFIG.9).

The protrusion portions145and146are disposed so as to be spaced apart from each other in the left-right direction on the lower side with respect to the protrusion portions143and144. The protrusion portions145and146include the screw holes145aand146ahaving female screws formed thereon, respectively. The screw holes145aand146aextend forward from the rear end surfaces of the protrusion portions145and146, respectively. The bolts92are threadedly engaged with the screw holes145aand146ato mount the second intermediate member70to the holding member140in the above-described manner (refer toFIG.9). The lengths of the protrusion portions145and146in the front-rear direction are shorter than the lengths of the protrusion portions143and144in the front-rear direction to allow the second intermediate member70to be held on the front side with respect to the first intermediate member60.

The above-described spring seat148is formed at the lower edge of the hollow circular cylindrical portion142. This holding member140is fitted in the gear housing20so as to bring the outer periphery of the annular portion141and the inner periphery of the hollow circular cylindrical portion142into abutment with the gear housing20in a state that the first intermediate member60and the second intermediate member70are mounted thereto. As a result, the holding member140is fixed to the gear housing20. Mounting the first intermediate member60and the second intermediate member70to the single holding member140automatically determines the relative positions of the first intermediate member60and the second intermediate member70, and therefore the relative positions of the first intermediate member60and the second intermediate member70do not have to be adjusted when the grinder10is assembled. In addition, as described above, the holding member140holds the sensor board holding member85holding the sensor80, and the first intermediate member60together. Therefore, mounting the sensor board holding member85also automatically determines the relative position of the sensor80to the first intermediate member60and the second intermediate member70, and therefore the position of the sensor80neither has to be adjusted.

Next, the sensor80will be described. The sensor80is a reflection-type photosensor in the present embodiment. As illustrated inFIG.4, the sensor80includes a light emitter82, a light receiver83, and a sensor board81on which the light emitter82and the light receiver83are mounted together. The light emitter82and the light receiver83are disposed on the front surface of the sensor board81. The sensor80is disposed near the bottom portion of the gear housing20to detect the displacements of the first intermediate member60and the second intermediate member70. More specifically, the sensor board81and the light emitter82are disposed behind the first intermediate member main body61in proximity to the first intermediate member main body61.

This sensor80is held by the sensor board holding member85illustrated in FIG.8. The sensor board holding member85is a generally Y-shaped plate-like member. The sensor board81, on which the light emitter82and the light receiver83are mounted, is held at a proximal portion from which the sensor board holding member85is forked. The sensor board81is fixed to the sensor board holding member85by any method (for example, screwing, snap-fit, or engagement using a partial heated deformation). Further, the through-holes87and88are formed near the forked distal ends of the sensor board holding member85, respectively.

The first intermediate member60is displaced between a position of blocking light emitted from the light emitter82and a position of not blocking this light due to the attachment of the side handle200. Similarly, the second intermediate member70is displaced between a position of blocking the light emitted from the light emitter82and a position of not blocking this light due to the attachment of the cover300. The sensor80detects the state in which the side handle200and the cover300are attached, based on whether or not the light receiver83receives the light based on these differences in the positions of the first intermediate member60and the second intermediate member70. In the following description, this will be described more specifically.

FIG.12schematically illustrates the positional relationship between the first intermediate member60and the second intermediate member70(refer toFIGS.4and9), and the sensor80when neither of the side handle200and the cover300is attached. In the state that neither of the side handle200and the cover300is attached, the first intermediate member60is located at the position where the first intermediate member main body61blocks the light emitted from the light emitter82as illustrated inFIG.12. Since the first intermediate member main body61is disposed in proximity to the light emitter82and the light receiver83, the light receiver83cannot receive the light emitted from the light emitter82. In the state that only the cover300of the side handle200and the cover300is attached, the first intermediate member main body61is also located at the position illustrated inFIG.12and therefore the light receiver83can neither receive the light emitted from the light emitter82, although this is not illustrated.

When only the side handle200is attached in the state illustrated inFIG.12, the first intermediate member60is displaced to the first attachment position illustrated inFIGS.3and10. At this time, light89emitted from the light emitter82passes through the second through-hole64and therefore is not blocked by the first intermediate member main body61, as illustrated inFIG.13. Further, at this time, the blocking portion73of the second intermediate member70is located at the position of not blocking the light89, and therefore the light receiver83cannot receive the light emitted from the light emitter82.

When the cover300is attached in the state illustrated inFIG.13, the second intermediate member70is displaced to the second attachment position illustrated inFIGS.3and11. At this time, the light89emitted from the light emitter82is blocked by the blocking portion73after passing through the second through-hole64, as illustrated inFIG.14. As a result, the light89is reflected by the blocking portion73and is received by the light receiver83.

In this manner, according to the above-described grinder10, the light89emitted from the light emitter82can be received by the light receiver83on the single sensor80only in the state that both the side handle200and the cover300are attached. In other words, the state in which both the side handle200and the cover300are attached can be detected using the single sensor80. Therefore, the present configuration can reduce the number of components and the cost compared to a configuration in which an individual sensor is prepared for each of the side handle200and the cover300.

Further, the first intermediate member60is configured to be rotated about the rotational axis AX1when any of the pressed portions62ato62cis pressed by the side handle200. This eliminates the necessity of securing a space for the displacement of the first intermediate member60in the front-rear direction, thereby allowing the grinder10to have a compact size in the front-rear direction.

Further, the second intermediate member70is pressed by the cover300(more specifically, the attachment portion320) and is linearly moved in the attachment direction of the cover300(i.e., upward) when the cover300is attached. This eliminates the necessity of a direction conversion mechanism, thereby contributing to the simplification of the apparatus configuration.

In the following description, a second embodiment of the present invention will be described with reference toFIGS.15and16. The second embodiment is different from the first embodiment in terms of using a sensor180instead of the sensor80, using a first intermediate member160instead of the first intermediate member60, and using a second intermediate member170instead of the second intermediate member70. InFIGS.15and16, components similar to the components in the first embodiment are identified by the same reference numerals as the first embodiment. In the following description, the second embodiment will be described focusing only on differences from the first embodiment. The sensor180is a transmission-type photosensor in the present embodiment. As illustrated inFIGS.15and16, the sensor180includes a light emitter182, a light receiver183, and a sensor board181on which the light emitter182and the light receiver183are mounted together. The first intermediate member160does not include the second through-hole64, but instead includes a cutout on the radial outer edge portion thereof. The second intermediate member170includes a blocking portion173instead of the blocking portion73. The blocking portion173extends downward from the rear edge of the base71.

The light emitter182and the light receiver183are arranged in such a manner that the blocking portion173and the first intermediate member main body61are located between the light emitter182and the light receiver183in the front-rear direction. In this configuration, the first intermediate member main body61is located at a position of blocking light emitted from the light emitter182when the first intermediate member160is located at the first non-attachment position, and the blocking portion173is located at a position of blocking the light emitted from the light emitter182when the second intermediate member170is located at the first non-attachment position (refer toFIG.16). In other words, when at least one of the side handle200and the cover300is not attached, the light emitted from the light emitter182is blocked by at least one of the first intermediate member160and the second intermediate member170. Therefore, the light receiver183cannot receive the light emitted from the light emitter182. On the other hand, the light emitted from the light emitter182can pass through the cutout of the first intermediate member160when the first intermediate member160is located at the first attachment position, and the blocking portion173is displaced to the position of not blocking the light emitted from the light emitter182when the second intermediate member170is located at the first attachment position (refer toFIG.15). In other words, when both the side handle200and the cover300are attached, the light emitted from the light emitter182is received by the light receiver183. Therefore, the state in which both the side handle200and the cover300are attached can be detected using the single sensor180.

Having described the embodiments of the present invention, the above-described embodiments are intended to only facilitate the understanding of the present invention, and are not intended to limit the present invention thereto. The present invention can be modified or improved without departing from the spirit thereof, and includes equivalents thereof. Further, each of the elements described in the claims and the specification can be combined in any manner or omitted in any manner within a range that allows it to remain capable of achieving at least a part of the above-described objects or bringing about at least a part of the above-described advantageous effects.

For example, the shapes and the forms of the components of the above-described grinder10are merely examples, and can be changed in any manner as long as the functions of these components can be maintained. For example, the pressed portions62ato62cof the first intermediate member60may protrude forward or rearward instead of protruding radially outward. Alternatively, the first intermediate member60may include a blocking portion protruding radially outward from the first intermediate member main body61instead of the second through-hole64. In this case, the light emitted from the light emitter82is blocked by the blocking portion when the first intermediate member60is located at the first non-attachment position, and the blocking portion is brought into a state of being displaced to the position of not blocking the light emitted from the light emitter82when the first intermediate member60is located at the first attachment position.

Further, the first intermediate member60may be indirectly pressed by the side handle200when the side handle200is attached. More specifically, an additional member that is displaced by being pressed by the side handle200may be provided, and the first intermediate member60may be displaced by this additional member. Similarly, the second intermediate member70may be indirectly pressed by the cover300when the cover300is attached.

Further, the first intermediate member60may be configured to be tilted by being pressed by the side handle200when the side handle200is attached instead of being configured to be rotated when the side handle200is attached. For example, the first intermediate member60may include a support shaft on the lower side of the first intermediate member60and be tilted about this support shaft in such a manner that the lower edge of the first intermediate member60approaches the front side.

Further, the second intermediate member70may be located at the position of blocking the light emitted from the light emitter82when being located at the second non-attachment position, and located at the position of not blocking the light emitted from the light emitter82when being located at the second attachment position. In this case, for example, a low-reflective coating material may be applied to the second intermediate member70in advance, and a reflection board may be disposed in such a manner that the first intermediate member60and the second intermediate member70are located between the reflection plate and the sensor80in the front-rear direction. Employing this layout allows the light receiver83to receive the light emitted from the light emitter82only in the state that both the side handle200and the cover300are attached.

Each of the sensors80and180is not limited to the photoelectric sensor, and may be any other known type of sensor. For example, an ultrasonic distance sensor may be employed. In this case, the state in which both the side handle200and the cover300are attached can also be detected if the first intermediate member60and the second intermediate member70are each configured to be displaced between a position of blocking an ultrasonic wave emitted from the sensor (hereinafter also referred to as a blocking position) and a position of not blocking this ultrasonic wave (hereinafter also referred to as a non-blocking position) according to whether the side handle200or the cover300is attached. For example, the first intermediate member60may be located at the blocking position when the side handle200is not attached, and be located at the non-blocking position when the side handle200is attached. Further, the second intermediate member70may be located at the blocking position when the cover300is not attached, and be located at the non-blocking position when the cover300is attached. Employing this configuration allows the sensor80or180to detect the state in which both the side handle200and the cover300are attached based on a difference in the detected distance. Alternatively, an eddy current displacement sensor may be employed. In this case, each of the first intermediate member60and the second intermediate member70is at least partially made from metal. Alternatively, a color sensor may be employed. In this case, the first intermediate member60and the second intermediate member70are colored in different colors from each other.

Further, the grinder10may include a notification unit for notifying the user that at least one of the side handle200and the cover300is not attached instead of or in addition to the configuration that permits or prohibits the driving of the electric motor31according to the attachment states of the side handle200and the cover300.

The notification method may be light emission, a sound output, a character display, or a combination of them. For example, the notification unit may include at least one of a light-emitting element such as an LED, a GUI screen, and a speaker.

Further, the above-described embodiments can be applied to not only the grinder10but also any tool configured to allow two types of accessories to be detachably attached thereto.

DESCRIPTION OF NUMERALS

10grinder20gear housing22second attachment portion23small bevel gear24large bevel gear25spindle26inner flange27lock nut28tool accessory29ato29cfirst attachment portion30motor housing31electric motor32motor shaft33controller40handle housing41switch50operation member60,160first intermediate member61first intermediate member main body62ato62cpressed portion63ato63cpressed surface64second through-hole65first though-hole67protrusion68spring70,170second intermediate member71base72pressed portion73,173blocking portion74support portion76third through-hole78spring seat79spring80,180sensor81,181sensor board82,182light emitter83,183light receiver85sensor board holding member87,88through-hole89light91,92bolt140holding member141annular portion142hollow circular cylindrical portion143,144,145,146protrusion portion143a,144a,145a,146ascrew hole147cutout148spring seat149spring housing portion200side handle210grip portion220attachment portion300cover310cover main body320attachment portionAX1, AX2rotational axis