Patent ID: 12246427

DETAILED DESCRIPTION OF THE EMBODIMENTS

In one or more of embodiments, the at least one elastic member may be disposed only one of between the at least one guiding member and the housing and between the at least one guiding member and the first part of the handle. According the present aspect, satisfactory sliding property can be achieved at the other of between the at least one guiding member and the housing and between the at least one guiding member and the first part of the handle. Therefore, the at least one guiding member can smoothly guide relative movement between the handle and the housing.

In one or more of embodiments, the at least one elastic member may be disposed only between the at least guiding member and the housing. The at least one guiding member may be disposed to be movable relative to the housing in the crossing direction. According to the present aspect, satisfactory sliding property can be achieved between the at least one guiding member and the first part of the handle. Therefore, the at least one guiding member can smoothly guide relative movement between the handle and the housing. Furthermore, according to the present aspect, the at least one elastic member and the at least one guiding member can be disposed on an outer surface of the housing. This enables easy assembly of the power tool.

In one or more of embodiments, the at least one elastic member may be at least one sponge fixedly attached to the housing. The sponge is easily deformable. Therefore, according to this aspect, the at least one elastic member can have a large amount of elastic deformation in the crossing direction. This results in improved effect in reducing transmission of vibration to the handle for vibration in the crossing-direction. Also, the sponge is made of a low-cost, lightweight material. This enables the power tool to have reduced cost and weight.

In one or more embodiments, the at least one guiding member may be fixedly attached to the at least one sponge. According to the present aspect, the at least one elastic member and the at least one guiding member are fixed relative to the housing. This enables easy assembly of the power tool.

In one or more embodiments, an allowable amount of movement of the handle relative to the housing in the axial direction may be larger than an allowable amount of movement of the at least one guiding member relative to the housing or the handle in the crossing direction. According to the present aspect, the allowable amounts of relative movements are set based on the magnitude of vibration caused. More specifically, in order to reduce the amount of vibration in the axial direction, that is, vibration of a relatively large magnitude, transmitted to the handle, the allowable amount of movement of the handle relative to the housing is set to a relatively large amount; whereas in order to reduce the amount of vibration in the crossing-direction, that is, vibration of a relatively small magnitude, transmitted to the handle, the allowable amount of movement of the at least one guiding member relative to the housing or the handle is set to a relatively small amount. That is, the two allowable amounts of relative movements are respectively optimized according to the required level of vibration-isolating performance. This prevents increase in size of the power tool.

In one or more embodiments, the at least one elastic member may include a first elastic member and a second elastic member disposed to be spaced apart from each other in the axial direction. According to the present aspect, the at least one elastic member may be subjected to a force in the crossing direction more concentrically in a small area compared to a case in which a single elastic member extends from where the first elastic member is located to where the second elastic member is located and a single guiding member extends from where the first elastic member is located to where the second elastic member is located. Therefore, the at least one elastic member can have an increased amount of elastic deformation. This results in improved effect in reducing transmission of vibration to the handle for vibration in the crossing-direction.

In one or more embodiments, the at least one guiding member may include a first guiding member and a second guiding member disposed to be spaced apart from each other in the axial direction. The at least one elastic member may be disposed so as to extend in the axial direction from where the first guiding member is located to where the second guiding member is located. According to the present aspect, the at least one elastic member may be subjected to a force in the crossing direction more concentrically in a small area compared to a case in which a single elastic member extends from where the first elastic member is located to where the second elastic member is located and a single guiding member extends from where the first elastic member is located to where the second elastic member is located. Therefore, the at least one elastic member can have an increased amount of elastic deformation. This results in improved effect in reducing transmission of vibration to the handle for vibration in the crossing-direction. Moreover, the at least one guiding member can have a shortened distance of extension as a whole. This enables the power tool to have a reduced weight. Furthermore, there is no need to distribute the at least one elastic member at where the first guiding member is located and where the second guiding member is located in the axial direction. This enables a simplified process for manufacturing.

In one or more embodiments, the at least one guiding member may be at least one pin having a circular cross section. According to the present aspect, satisfactory sliding property can be achieved in relation to the at least one guiding member. Also, manufacturing can be easy.

In one or more embodiments, the at least one guiding member and the at least one elastic member may be disposed at three locations around a circumferential direction with respect to the rotation axis. According to the present aspect, the at least one guiding members can guide relative movement between the handle and the housing with more stability. Furthermore, the at least one elastic member elastically deform in different directions from each other, respectively. This results in improved effect in reducing transmission of vibration to the handle for vibration in the crossing-direction.

The embodiment of the present disclosure is now described in more detail with reference to the drawings.

In this embodiment, a rotary hammer (hammer drill)101is described as an example of a power tool according to the present teachings. The rotary hammer101is a hand-held power tool that may be used for processing operations such as chipping and drilling. The rotary hammer101is configured to be capable of performing the operation (hereinafter referred to as a hammering operation) of linearly reciprocally driving a tool accessory91along a driving axis A1and of performing the operation (hereinafter referred to as a drilling operation) of rotationally driving the tool accessory91around the driving axis A1.

First, the general structure of the rotary hammer101is described with reference toFIGS.1and2. As shown inFIG.1, an outer shell of the rotary hammer101is mainly formed by a body housing10and a handle17connected to the body housing10.

The body housing10is a hollow body that accommodates parts such as a spindle31, a driving mechanism5, a motor2, and the like. The spindle31is an elongate member having a hollow circular cylindrical shape. At its end portion in the axial direction, the spindle31has a tool holder32configured to removably hold the tool accessory91. A longitudinal axis of the spindle31defines a driving axis A1of the tool accessory91. The body housing10extends along the driving axis A1. The tool holder32is disposed within one end portion of the body housing10in an extension direction of the driving axis A1(hereinafter simply referred to as a driving-axis direction).

The handle17is disposed in one side of the body housing in the axial direction (i.e. the side opposite to the side in which the tool holder31is disposed). The handle17includes a grip part171extending in a direction crossing (more specifically, generally orthogonal to) the driving axis A1. The grip part171is a portion intended to be held by a user and is formed so as to protrude in the direction crossing the driving axis A1.

In the following description, for convenience sake, the extension direction of the driving axis A1(the longitudinal direction of the body housing10) is defined as a front-rear direction of the rotary hammer101. The side of one end of the rotary hammer101in the front-rear direction in which the tool holder32is disposed is defined as a front side of the rotary hammer101; whereas the opposite side (the side of one end in which the motor2is disposed) is defined as a rear side of the rotary hammer101. The direction that is orthogonal to the driving axis A1and corresponds to a direction in which the grip part171extends is defined as an up-down direction of the rotary hammer101. In the up-down direction, the side of one end in which the body housing10is located is defined as an upper side and the side of the protruding end of the grip part171is defined as a lower side. Further, the direction that is orthogonal to both the front-rear direction and the up-down direction is defined as a left-right direction of the rotary hammer101. In the left-right direction, the side to the right when viewed from the rear side to the front side is defined as a right side of the rotary hammer101and the opposite side is defined as a left side of the rotary hammer101.

The detailed structure of the rotary hammer101is now described. First, the structure of the body housing10is described. As shown inFIG.2, the body housing10has a gear housing13and a motor housing11. The spindle31and the driving mechanism5are accommodated in the gear housing13. The gear housing13has a front end portion of a hollow circular cylindrical shape. The portion is referred to as a barrel part131. The remaining portion of the body housing10other than the barrel part131has a generally rectangular box-like shape. A bearing support15is fitted into a rear end portion of the gear housing13.

The motor2is accommodated in the motor housing11. The motor housing11is disposed adjacent to and in the rear side of the gear housing13. The motor housing11is a single (integral) member and includes a tubular part111and a bearing holding part113.

The tubular part111is a tubular member extending in the axial direction. More specifically, the tubular part111includes a front end portion and a rear side portion located in the rear of the front end portion. The front end portion of the tubular part111has a width (in other words, a diametrical dimension around the driving axis A1) generally identical to that of the rear end portion of the gear housing13. The rear side portion of the tubular part111has a smaller outer diameter than the front end portion of the tubular part111. The bearing holding part113protrudes rearward from a rear end surface of the tubular part111.

With the motor2disposed within the tubular part111, a baffle plate16is fitted into the tubular part111and connected to the tubular part111by a plurality of screws114. The motor2is thus fixedly held within the motor housing11. The baffle plate16also serves to direct flow of air generated by a cooling fan27described later. The motor housing11and the gear housing13are fixedly connected together by means of fixation such as screws or the like.

The internal structures of the body housing10are now described. First, the motor2is described. In this embodiment, an AC motor, which may be powered by an external AC power source, is employed as the motor2. As shown inFIG.2, the motor2has: a motor body20including a stator and a rotor; and a motor shaft25configured to rotate together with the rotor. In this embodiment, a rotation axis A2of the motor2(in other words, of the motor shaft25) extends below the driving axis A1and in parallel to the driving axis A1.

The motor shaft25is supported via two bearings251and252so as to be rotatable around the rotation axis A2relative to the body housing10. The front bearing251is held on a rear surface side of the bearing support15, and the rear bearing252is held within the bearing holding part113of the motor housing11. The cooling fan27for cooling the motor2is fixed to a portion of the motor shaft25between the motor body20and the front bearing251.

A front end portion of the motor shaft25extends through the bearing support15and protrudes into the gear housing13. A pinion gear255is fixed to this end portion of the motor shaft25that protrudes into the gear housing13.

The spindle31is now described. The spindle31is a final output shaft of the rotary hammer101. As shown inFIG.2, the spindle31is arranged within the gear housing13along the driving axis A1and is supported to be rotatable around the driving axis A1relative to the body housing10. The spindle31is configured as an elongate, stepped hollow circular cylindrical member.

A front half of the spindle31forms the tool holder32to or in which the tool accessory91can be removably attached. The tool accessory91is inserted into a bit-insertion hole330formed in a front end portion of the tool holder32such that a longitudinal axis of the tool accessory91coincides with the driving axis A1. The tool accessory91is held in the insertion hole330so as to be movable relative to the tool holder32in the axial direction while its rotation around the axial direction is restricted (blocked). A rear half of the spindle31forms a cylinder33configured to slidably hold a piston65described later. The spindle31is supported by bearings316and317. The bearing316is held within the barrel part131and the bearing317is held within an inner housing132formed integrally with the gear housing13.

The driving mechanism5is now described. In this embodiment, the driving mechanism5is configured to be capable of performing hammering operations of linearly reciprocally driving the tool accessory91along the driving axis A1and of performing drilling operations of rotationally driving the tool accessory91around the driving axis A1.

More specifically, the driving mechanism5includes a striking mechanism6for performing hammering operations. The striking mechanism6includes a motion-converting member61, an arm part62, a piston65, a striker67, and an impact bolt68. The motion-converting member61is disposed around an intermediate shaft41. The intermediate shaft41extends in parallel to the rotation axis A2of the motor shaft25. The intermediate shaft41is rotatably supported by two bearings (not shown) disposed to be immovable relative to the body housing10. Rotational force of the motor shaft25is transmitted to the intermediate shaft41via a gear (not shown) meshed with the pinion gear255attached to the front end of the motor shaft25. The motion-converting member61is configured to oscillate (pivot or rock back and forth) in the front-rear direction in response to rotation of the intermediate shaft41. The arm part62connects the motion-converting member61and the piston65. Rotational motion of the intermediate shaft41is converted into linear motion by the motion-converting member61and transmitted to the piston65via the arm part62.

The piston65is a bottomed hollow circular cylindrical member, and is disposed within the cylinder33of the spindle31so as to be slidable along the driving axis A1. The striker67is disposed within the piston65so as to be slidable along the driving axis A1. An internal space of the piston65in the rear of the striker67is defined as an air chamber that serves as an air spring. The impact bolt68is an intermediate element for transmitting kinetic energy of the striker67to the tool accessory91. The impact bolt68is disposed within the tool holder32in front of the striker67so as to be movable along the driving axis A1.

When rotational motion of the intermediate shaft41is converted into linear motion and transmitted to the piston65as described above, the piston65is moved in the front-rear direction. At this time, the air pressure within the air chamber fluctuates and the striker67slides in the front-rear direction within the piston65by the action of the air spring. More specifically, when the piston65is moved forward, the air within the air chamber is compressed and its internal pressure increases. Thus, the striker67is pushed forward at high speed by the action of the air spring and strikes the impact bolt68. The impact bolt68transmits the kinetic energy of the striker67to the tool accessory91. Thus, the tool accessory91is linearly driven along the driving axis A1. On the other hand, when the piston65is moved rearward, the air within the air chamber expands and its internal pressure decreases so that the striker67is retracted (moved) rearward. The tool accessory91moves rearward along with the impact bolt68by being pressed against a workpiece. In this manner, the striking mechanism6repetitively performs the hammering operation.

Furthermore, the driving mechanism5includes a rotation-transmitting mechanism (not shown) for drilling operations. The rotation-transmitting mechanism is configured to transmit rotational motion of the intermediate shaft41to the spindle31and rotationally drive the tool accessory91around the driving axis A1. More specifically, a driving gear (not shown) is fixed to a front end portion of the intermediate shaft41. This driving gear is meshed with a driven gear79fixed to an outer periphery of the cylinder33of the spindle31. Therefore, the spindle31is rotated together with the driven gear79in response to rotation of the driving gear together with the intermediate shaft41. The drilling operation is thus performed in which the tool accessory91held by the tool holder32is rotationally driven around the driving axis A1.

In this embodiment, the rotary hammer101is switched between three action modes, namely a hammer-drill mode (rotation with hammering), a hammer mode (hammering only), and a drill mode (rotation only). The hammer-drill mode is a mode in which the striking mechanism6and the rotation-transmitting mechanism are both driven, so that the hammering operation and the drilling operation are both performed, i.e. the tool accessory91is simultaneously rotated and axially hammered. The hammer mode is a mode in which power transmission for the drilling operation is interrupted and only the striking mechanism6is driven, so that only the hammering operation is performed, i.e. the tool accessory91is only hammered (without rotation). The drill mode is a mode in which power transmission for the hammering operation is interrupted and only the rotation-transmitting mechanism is driven, so that only the drilling operation is performed, i.e. the tool accessory91is only rotated (without hammering). These action modes are switched in response to the manipulation of a mode-changing dial80. Such mechanisms for switching between the action modes are well known and thus not described here.

The above-described driving mechanism5is disclosed in, for example, US Patent Applications No. 2015/144366 and NO. 2016/136801, the disclosed contents of all of which are hereby fully incorporated herein by reference.

The structure of the handle17is now described. As shown inFIGS.1and2, the handle17includes the grip part171and a tubular part172. The tubular part172is a tubular portion extending in the front-rear direction. As shown inFIG.2, the tubular part172is disposed radially outside of the motor housing11with respect to the rotation axis A2so as to circumferentially surround the motor housing11. The grip part171is an elongate hollow body extending from a rear end of the tubular part172in a direction crossing the rotation axis A2. In this embodiment, the tubular part172is integrally formed with a front side portion of the grip part171. The integrally formed tubular part172and the front end portion of the grip part171are connected with a rear side portion of the grip part171by screws so as to form the handle17.

A power cable179extends from the lower end of the grip part171and can be connected to an external alternate current (AC) power source. The grip part171has a trigger141to be depressed (pulled) by a user. A switch142configured to be turned ON in response to a depressing operation of the trigger141is disposed within the grip part171. In the rotary hammer101, when the switch142is turned ON, the motor2is energized and the driving mechanism5is driven so that the hammering operation and/or the drilling operation is performed.

In this embodiment, the body housing10and the handle17are connected via an extendable bellows198. More specifically, as shown inFIGS.2and4, the bellows198has a ring shape circumferentially surrounding the rotation axis A2. A front end of the bellows198is connected with the motor housing11and a rear end of the bellows198is connected with the tubular part172of the handle17.

In this embodiment, the rotary hammer101is configured to reduce the amount of vibration caused by the operation of the motor2and the driving mechanism5to be transmitted to the handle17. The structure for isolating such vibration is described below.

As a vibration-isolating structure, the body housing10and the handle17are configured to be movable relative to each other in the front-rear direction. This relative movement is slidably guided by three guiding members191disposed between the body housing10(more specifically, the motor housing11) and the handle17(more specifically, the tubular part172) and extending in the front-rear direction. More specifically, as shown inFIGS.2to4, three grooves115are formed in an outer surface of the tubular part111of the motor housing11and extend in the front-rear direction. As shown inFIG.3, a front end of each groove115reaches a front end of the tubular part111and a rear end of each groove115ends at a rear side inner surface116without reaching the rear end surface117of the tubular part111. As shown inFIG.4, the three grooves115are respectively disposed at three locations around a circumferential direction with respect to the rotation axis A2. In this embodiment, the three grooves115are arranged equiangularly (that is, to be rotationally symmetric through 120 degrees with respect to the rotation axis A2). As shown inFIG.9, each groove115has an arc-shaped cross section.

As shown inFIGS.3and9, the three guiding members191are respectively disposed inside the three grooves115. Each guiding member191is partially accommodated within the corresponding groove115, with its majority located outside of the groove115. As shown inFIG.3, the length of each guiding member191is slightly smaller than the length of the corresponding groove115. The front end of each groove115is blocked with the baffle plate16. Therefore, the guiding member191is located within the groove115in a state in which its movement in the front-rear direction is substantially restricted by the baffle plate191and the rear side inner surface161.

As shown inFIG.9, in this embodiment, the guiding member191is in the form of a pin having a circular cross section. In particular, in this embodiment, the guiding member191has a hollow shape. This enables the guiding member191and thus the rotary hammer101to have reduced weights.

Also, as shown inFIGS.3and9, three guiding grooves174are formed in an inner surface of the tubular part172of the handle17and extend in the front-rear direction. As shown inFIG.9, each guiding groove174has an arc-shaped cross section conforming to an outer peripheral surface of the corresponding guiding member191. As shown inFIG.8, the three guiding grooves174are respectively located at positions corresponding to the three grooves115and the three guiding members191, respectively. The handle17can move relative to the body housing10in the front-rear direction by having the inner surface of the tubular part172, in which the guiding grooves174are formed, sliding on the guiding members191.

The use of a pin having a circular cross section as the guiding member191as in this embodiment can provide satisfactory sliding property and also enables easy manufacturing. Note that, however, each guiding member191and its corresponding guiding groove174can have freely-selected shapes conforming to each other. Also, in this embodiment, the guiding members191are respectively disposed at three locations around the circumferential direction. Therefore, relative movement between the handle17and the body housing10can be guided with more stability.

As shown inFIGS.3and9, within each groove115, an elastic member192is disposed between the tubular part111and the guiding member191. The elastic member192in this embodiment is formed of sponge, that is, resin made by foam molding (e.g., polyurethane). In this embodiment, the elastic member192is fixedly attached to the tubular part111by using freely-selected means for fixation (e.g., adhesive). Furthermore, the guiding member191is fixedly attached to the elastic member192by using freely-selected means for fixation (e.g., adhesive). According to this structure, the elastic members192and the guiding members191are fixed to the tubular part111. This enables easy assembly of the rotary hammer101(more specifically, easy process of fitting the tubular part111into the tubular part172of the handle17). Note that, however, the means for fixation may be omitted at least between the tubular part111and the elastic member192or between the guiding member191and the elastic member192. In this embodiment, the elastic member192is disposed in a slightly compressed state between the tubular part111and the guiding member191. When subjected to a force in a direction crossing the rotation axis A2(also referred to as a crossing direction), the elastic member192can elastically deform further in the crossing direction. By initially placing the elastic member192in this slightly compressed state, satisfactory sliding property can be achieved between the guiding member191and the tubular part172.

As such, the guiding member191is fixed to the motor housing11via the elastic member192, rather than being directly fixed to the motor housing11. Therefore, the guiding member191is movable relative to the motor housing11in the crossing direction according to the amount of elastic deformation of the elastic member192in the crossing direction. In other words, the guiding member191is held in a floating state (in a state in which the guiding member191is floated) between the tubular part111and the tubular part172.

As shown inFIG.3, in this embodiment, two elastic members192are provided for each groove115. One of the elastic members192is disposed in the front end of the groove115and the other one of the elastic members192is disposed in the rear end of the groove115. A clearance radially extends between the tubular part111and the guiding member191in the space between the two elastic members192.

In such a structure in which the handle17is movable relative to the body housing10in the front-rear direction, the handle17is biased rearward (in other words, in a direction away from the spindle31in the front-rear direction). More specifically, as shown inFIGS.4and5, the rotary hammer101includes four biasing springs193. As shown inFIG.5, the biasing spring193is in the form of a coil spring and is disposed in a compressed state between the tubular part111and the tubular part172. The tubular part172includes a projection175near its front end. The projection175protrudes frontward inside the outer periphery of the tubular part172. A stepped part176is formed at the base of the projection175by having an increased diameter. The biasing spring193is disposed such that the projection175is located within the biasing spring193and the stepped part176serves as a seat for the spring. The handle17is always biased rearward by the biasing spring193.

As shown inFIG.4, in this embodiment, the biasing spring193and the projection175are disposed near every corner of the rotary hammer101such that four pairs of the biasing spring193and the projection175are arranged symmetrical both laterally and vertically in the longitudinal cross section of the rotary hammer101. Therefore, the handle17can be biased uniformly on a plane orthogonal to the rotation axis A2.

With such a structure, in the rotary hammer101, the handle17is movable relative to the body housing10in the front-rear direction between an initial position shown inFIGS.1to3andFIG.5and a closest position shown inFIGS.6,7, and10. The initial position is a relative position of the handle17when no force is applied to the body housing10and the handle17in the front-rear direction. The closest position is another relative position of the handle17when a force is applied to the body housing10and the handle17in the front-rear direction so that the body housing10and the handle17are closest to each other. The closest position is defined by the rear end surface117(seeFIG.3) of the tubular part111abutting on an abutment part173(seeFIG.3) of the tubular part172. The abutment part173is a part protruding radially inward from the inner surface of the tubular part172and serves as a stopper for restricting movement of the handle17relative to the body housing10in the front-rear direction. Meanwhile, the initial position is defined by abutment parts (not shown) respectively provided on the motor housing11and the handle17abutting with each other.

According to the rotary hammer101described hereinabove, when the tool accessory91is subjected to a rearward reaction force during the hammering operation, the spindle31holding the tool accessory91as well as the body housing10supporting the spindle31and the driving mechanism5are also subjected to a rearward reaction force. This causes the handle17to move from the initial position to the closest position relative to the body housing10(in practice, the body housing10moves since the handle17is held by a user). That is, while being slidably guided by the guiding member191, the body housing10and the handle17move relative to each other in the front-rear direction so that the handle17gets closer to the spindle31against a biasing force from the biasing spring193. At this time, the reaction force is partially cushioned by elastic deformation of the biasing spring193. This cushioning effect serves to reduce transmission of vibration to the handle17for vibration generated in the front-rear direction due to the reaction force.

Furthermore, according to the rotary hammer101, when vibration is generated in a direction crossing the front-rear direction (hereinafter also referred to as a crossing direction) due to the operation of the motion converting member61and/or the motor2, the elastic member192disposed between the motor housing11and the tubular part172of the handle17elastically deforms in the direction of the vibration and thereby absorbs the vibration. This serves to reduce transmission of vibration to the handle17also for vibration in the crossing direction.

Furthermore, according to the rotary hammer101, the elastic member192is disposed only between the guiding member191and the motor housing11but not between the guiding member191and the tubular part172of the handle17. Therefore, satisfactory sliding property can be achieved between the guiding member191and the tubular part172. Therefore, the guiding member191can smoothly guide relative movement between the body housing10and the handle17.

Furthermore, easily deformable sponge is used as the elastic member192. Therefore, the elastic member192can have an increased amount of elastic deformation in the crossing direction. This results in improved effect in reducing transmission of vibration to the handle17for vibration in the crossing direction.

Furthermore, in the rotary hammer101, two elastic members192are provided for one guiding member191and are disposed to be spaced apart from each other in the front-rear direction. Therefore, the elastic member192may be subjected to a force in the crossing direction more concentrically in a small area compared to a case in which a single elastic member192having the same length as the guiding member191is used (that is, the guiding member191and the elastic member192are in contact with each other over the overall length of the guiding member191). Therefore, the elastic member192can have an increased amount of elastic deformation, and this results in improved effect in reducing transmission of vibration to the handle17for vibration in the crossing direction.

Furthermore, the elastic members192are respectively disposed at three locations around the circumferential direction. Therefore, the elastic members192at different circumferential positions elastically deform in directions different from each other. This results in improved effect in reducing transmission of vibration to the handle17for vibration in the crossing direction.

In the rotary hammer101, in this embodiment, the allowable amount of movement of the handle17relative to the body housing10in the front-rear direction (that is, the amount of movement of the handle17between the initial position and the closest position) may be set larger than the allowable amount of the guiding member191relative to the body housing10in the crossing direction (in other words, the amount of elastic deformation of the elastic member192from its initial state). Normally, vibration in the front-rear direction due to the reaction force is larger than vibration in the crossing direction. Therefore, with this structure, the two allowable amounts of relative movements are respectively optimized according to the amount of vibration (that is, according to the required level of vibration-isolating performance). This prevents increase in size of the rotary hammer101.

Correspondences between the features of the above-described embodiment and the features of the claims are as follows. The features of the above-described embodiment are, however, merely exemplary and do not limit the features of the present invention. The rotary hammer101is an example of the “power tool”. The spindle31is an example of the “final output shaft”. The driving axis A1is an example of the “driving axis”. The motor2is an example of the “motor”. The driving mechanism5is an example of the “driving mechanism”. The body housing10(more specifically, the motor housing11) is an example of the “housing”. The handle17is an example of the “handle”. The tubular part172is an example of the “first part”. The grip part171is an example of the “second part”. The biasing spring193is an example of the “biasing member”. The guiding member191is an example of the “at least one guiding member”. The elastic member192is an example of the “at least one elastic member”.

The above-described embodiment is merely an exemplary embodiment of the present disclosure, and power tools, such as rotary hammers and hammer drills, according to the present disclosure are not limited to the rotary hammer101of the illustrated structure. For example, the following modifications may be made. One or more of these modifications may be employed in combination with the rotary hammer101of the above-described embodiment or any one of the claimed aspects.

Instead of the guiding member191and the elastic member192, guiding members191aand an elastic member192amay be used as shown inFIG.11. In this example, two guiding members191a, namely a front guiding member and a rear guiding member, are provided for one groove115. The guiding members191aare coaxially disposed to be spaced apart from each other in the front-rear direction. The front guiding member191ais disposed in the front end of the groove115and the rear guiding member191ais disposed in the rear end of the groove115. Therefore, the two guiding members191aas a whole can deliver a guiding performance equivalent to that by the above-described guiding member191. The elastic member192ais disposed to extend over the overall length of the groove115in the front-rear direction.

With this structure, the elastic member192amay be subjected to a force in the crossing direction concentrically in a small area, as with the structure shown inFIG.3. Therefore, the elastic member192acan have an increased amount of elastic deformation, and this results in improved effect in reducing transmission of vibration to the handle17for vibration in the crossing direction. In a further alternative embodiment, elastic members192amay also be disposed to be spaced apart from each other in the front-rear direction. That is, the elastic member192amay only be disposed at positions where the guiding members191aare located in the front-rear direction. This provides the similar effect as with the structure shown inFIG.11. Note that, in a further alternative embodiment, both the guiding member191and the elastic member192may be disposed to extend over the overall length of the groove115.

The material of the elastic member192is not limited to sponge, but may be a freely-selected elastic material that is elastically deformable in the crossing direction. For example, the elastic member192may be formed of flexible resin such as silicone resin, urethane, and the like.

A freely-selected number of elastic members192may be used. For example, the guiding member191and the elastic member192may be disposed at four locations around the circumferential direction similarly to the biasing member193.

In addition to between the tubular part111and the guiding member191, the elastic member192may also be disposed between the tubular part172and the guiding member191(that is, on the interface where sliding occurs). In this case, the elastic member192may be formed of a material more wear-resistant than sponge.

Alternatively, instead of between the tubular part111and the guiding member191, the elastic material192may be disposed between the tubular part172and the guiding member191such that the guiding member191is movable relative to the handle17in the crossing direction. In this case, the guiding member191and the tubular part111(more specifically, an inner surface of a guiding groove formed in the tubular part111) may slide relative to each other. The elastic member192may be disposed within the groove formed in the inner surface of the tubular part172.

In the above-described embodiments, the rotary hammer101capable of performing hammering operations and drilling operations is illustrated as an example of a power tool. However, the power tool may alternatively be an electric hammer (scraper, demolition hammer) capable of performing hammering operations only.

DESCRIPTION OF THE REFERENCE NUMERALS

2: motor,5: driving mechanism,6: striking mechanism,10: body housing,11: motor housing,13: gear housing,15: bearing support,16: baffle plate,17: handle,20: motor body,25: motor shaft,27: cooling fan,31: spindle,32: tool holder,33: cylinder,41: intermediate shaft,61: motion-converting member,62: arm part,65: piston,67: striker,68: impact bolt,79: driven gear,80: mode-changing dial,91: tool accessory,101: rotary hammer,111: tubular part,113: bearing holding part,114: screw,115: groove,116: rear side inner surface,117: rear end surface,131: barrel part,132: inner housing,141: trigger,142: switch,171: grip part,172: tubular part,173; abutment part,174: guiding groove,175: projection,176: stepped part,179: power cable,191,191a: guiding member,192,192a: elastic member,193: biasing spring,198: bellows,251,252: bearing,255: pinion gear,316,317: bearing,330: bit-insertion hole, A1: driving axis, A2: rotation axis.