Handle and power tool comprising same handle

To provide a handle that is effective at achieving both vibration resistance and usability. A handle attached to a tool body of a power tool has: a grip portion; a connecting portion that connects to the tool body; elastic element interposing regions that are formed between the grip portion and the connecting portion; elastic elements disposed in the elastic element interposing regions; a powder filling region formed between the grip portion and connecting portion; and a plurality of powder bodies that fill the powder filling region.

TECHNICAL FIELD

The present invention relates to a handle for a hand-held power tool.

BACKGROUND ART

Japanese non-examined laid-open Patent Publication No. 2005-138240 discloses a handle for a hand-held power tool. This handle has an elastic body formed of elastomer between a fixed part fixed to a tool body and a grip part.

Problem to be Solved by the Invention

In the above-described known handle, transmission of vibration caused in the tool body to the grip part is reduced by the elastomer elastic body.

In order to enhance the vibration proofing effect in a vibration proofing structure using an elastomer elastic body, it is necessary to soften the elastomer. If the elastomer is softened, however, the rigidity of the handle as a whole is reduced. Therefore, connection of the grip part with respect to the fixed part becomes unstable, so that the operability for a user holding the grip part is deteriorated. Thus, in the handle using elastomer, a tradeoff relation exists between the rigidity and the vibration proofing effect of the handle.

Accordingly, it is an object of the present invention to provide a handle that is effective in achieving both vibration-proof property and operability.

Means for Solving the Problem

In order to solve the above-described problem, according to a preferred aspect of the present invention, a handle which is mounted to a tool body of a power tool is provided. The handle has a grip, a connection part which is connected to the tool body, an elastic element interposing region formed between the grip and the connection part, an elastic element disposed in the elastic element interposing region, a powder filling region formed between the grip and the connection part, and powders filled in the powder filling region. The elastic element interposing region and the powder filling region may be formed as separate regions, or they may be formed integrally with each other as one region. The “power tool” typically represents a hand-held power tool such as an electric grinder and an impact tool, but also suitably includes a shouldering type power tool such as a bush cutter. Further, the “handle” of this invention suitably includes a main handle fixed to a power tool and an auxiliary handle which is removably attached separately from the main handle.

According to this invention, the grip is connected to the connection part via the elastic element and the powders. When an operation is performed with the connection part mounted to the tool body of the power tool, the elastic element elastically deforms in response to vibration caused in the tool body. As a result, transmission of vibration to the grip is reduced. The powders contact each other and vibrate in response to vibration caused in the tool body. At this time, frictional resistance is generated between the powders. As a result, transmission of vibration to the grip is reduced. The amount of elastic deformation of the elastic element is increased by reducing the hardness of the elastic element. Thus, the kinetic energy absorbed by elastic deformation of the elastic element is increased. Therefore, vibration which is transmitted to the grip is effectively reduced. On the other hand, the rigidity of the elastic element is reduced by reducing the hardness of the elastic element. The reduction of rigidity of the elastic element is however compensated by the powders. Thus, reduction of rigidity of the whole handle is prevented. Therefore, vibration which is transmitted from the connection part to the grip is effectively reduced, and the grip is stably held by the user. Specifically, the acceleration generated in the handle when a user holds the grip and operates the handle is smaller than the acceleration of vibration caused in the tool body. Therefore, the power inputted into the grip is received by the powders, so that the grip is stably held by the user. As a result, the vibration-proof property and operability of the handle is improved.

According to a further aspect of the handle of the present invention, the handle has a bag filled with the powders, and the bag is disposed in the powder filling region. The “bag” is preferably formed of a flexible material such as rubber, cloth and vinyl.

According to this aspect, with the structure in which the powders are filled in the bag, the powders can be easily arranged in the powder filling region.

According to a further aspect of the handle of the present invention, the elastic element interposing region and the powder filling region are formed side by side in a direction from a region of the connection part which is connected to the tool body toward the grip. Specifically, the elastic element interposing region and the powder filling region are arranged in order in a direction from a region of the connection part which is connected to the tool body toward the grip. In other words, the elastic element interposing region and the powder filling region are arranged side by side.

According to a further aspect of the handle of the present invention, the elastic element interposing region and the powder filling region are formed side by side in a direction crossing the direction from a region of the connection part which is connected to the tool body toward the grip. Specifically, the elastic element interposing region and the powder filling region are arranged in order in a direction crossing the direction from a region of the connection part which is connected to the tool body toward the grip. In other words, the elastic element interposing region and the powder filling region are arranged in parallel.

According to a further aspect of the handle of the present invention, the connection part is connected to the tool body by threadably engaging with the tool body. The grip and the connection part extend in a prescribed direction, and the connection part is arranged inside the grip. The handle has a rotation stopper that prevents the grip and the connection part from rotating around the prescribed direction by a prescribed amount or more with respect to each other. Typically, the rotation stopper is formed both in the elastic element interposing region and in the powder filling region. The rotation stopper may be formed in either the elastic element interposing region or the powder filling region.

According to this aspect, with the structure in which the rotation stopper prevents the grip and the connection part from rotating by a prescribed amount or more with respect to each other, operability of the handle is improved.

According to a further aspect of the handle of the present invention, the rotation stopper is formed both in the elastic element interposing region and in the powder filling region. In the case in which the elastic element interposing region and the powder filling region are separately formed, the rotation stopper is provided in both the elastic element interposing region and the powder filling region. With this structure, the grip can be effectively prevented from rotating with respect to the connection part.

According to a further aspect of the handle of the present invention, the powder filling region is formed inside the elastic element.

According to this aspect, the elastic element and the powders can be combined into a unit. This structure is effective in size reduction and improvement of assemblability of the unit of the elastic element and the powders. The unit is applied, for example, in a handle connecting part of a bush cutter as the power tool.

According to a different aspect of the present invention, a power tool having the handle according to any one of the above-described aspects is provided. The elastic element and the powders are arranged to reduce vibration which is caused in the tool body in a first direction and a second direction different from the first direction and transmitted from the connection part to the grip. As for “the first direction and the second direction different from the first direction” here, typically as a plurality of directions crossing a longitudinal direction of the grip, the longitudinal direction of the power tool is defined as the first direction, and a direction crossing the longitudinal direction of the power tool is defined as the second direction. Further, typically, the elastic element compressively deforms. Particularly, the elastic element compressively deforms in the first direction.

According to this aspect, operability of the grip (the handle) for operating the power tool is improved while transmission of vibration to the grip is prevented. Particularly, vibration which is caused in the tool body in the first and second directions and transmitted to the grip is effectively reduced by the elastic element and the powders.

According to a further aspect of the power tool of the present invention, the power tool includes an operation rod as the tool body, a cutting unit that is disposed on one end of the operation rod and rotatably supports a cutting blade, and a driving unit that is disposed on the other end of the operation rod and drives the cutting blade. The handle is connected to the operation rod. Further, the elastic element interposing region of the handle is formed between the operation rod and the connection part around a center line of the operation rod, and the powder filling region is formed in the elastic element. Specifically, the powder filling region is formed in the inside of the elastic element. In this case, preferably, a plurality of such elastic elements may be arranged in a circumferential direction around the center line of the operation rod, and the powders may be filled inside the elastic elements.

According to this aspect, operability of the grip (the handle) for operating the power tool is improved while transmission of vibration to the grip of the power tool is prevented.

According to a further aspect of the power tool of the present invention, a tool bit as an accessory tool is coupled to a front end region of the tool body. The power tool is configured such that the tool bit performs a hammering operation on a workpiece by linear motion at least in its axial direction. The handle is disposed on the tool body on a side opposite from the tool bit. The handle has a connecting region which connects the handle to the tool body so as to allow the handle to move with respect to the tool body in the axial direction of the tool bit. Further, the elastic element interposing region and the powder filling region are formed in the connecting region.

According to this aspect, in the power tool in which the tool bit performs a hammering operation on a workpiece by linear motion at least in its axial direction, operability of the grip (the handle) for operating the power tool is improved while transmission of vibration to the grip of the power tool is prevented.

According to a further aspect of the power tool of the present invention, a tool bit is coupled to a front end region of the tool body. The power tool is configured such that the tool bit performs a hammering operation on a workpiece by linear motion at least in its axial direction. The handle is disposed on the tool body on a side opposite from the tool bit. The handle has two connecting regions which are spaced apart from each other in a direction crossing the axial direction of the tool bit and which connect the handle to the tool body so as to allow the handle to move with respect to the tool body in the axial direction of the tool bit. Further, the elastic element interposing region and the powder filling region are formed in at least one of the connecting regions. The elastic element interposing region and the powder filling region may be formed in both of the connecting regions of the handle.

According to this aspect, in the power tool in which the tool bit performs a hammering operation on a workpiece by linear motion at least in its axial direction and the handle is connected to the tool body at two points, operability of the grip (the handle) for operating the power tool is improved while transmission of vibration to the grip of the power tool is prevented.

Effect of the Invention

According to the present invention, a handle that is effective in achieving both vibration-proof property and operability is provided.

Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.

BEST MODES FOR CARRYING OUT THE INVENTION

Each of the additional features and method steps disclosed above and below may be utilized separately or in conjunction with other features and method steps to provide improved handles, power tools and devices utilized therein. Representative examples of this invention, which examples utilized many of these additional features and method steps in conjunction, will now be described in detail with reference to the drawings. This detailed description is merely intended to teach a person skilled in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed within the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe some representative examples of the invention, which detailed description will now be given with reference to the accompanying drawings.

(First Embodiment of the Invention)

A first embodiment of the present invention is now described with reference toFIGS. 1 to 5, 11 and 12. In the first embodiment, a side grip100is explained which is mounted, for example, to an electric grinder150shown inFIG. 11or a hammer drill shown inFIG. 12as a representative example of a hand-held power tool according to the present invention.

The side grip100mainly includes a grip body110which is detachably connected to a tool body of a power tool, a grip part120to be held by a user, an elastic rubber130and powder140. The grip body110, the grip part120, the elastic rubber130and the powder140are example embodiments that correspond to the “connection part”, the “grip”, the “elastic element” and the “powder”, respectively, in the present invention.

As shown inFIGS. 1 and 2, the grip body110includes a metal mounting bolt111and a resin bolt holder113which are coaxially arranged. One end of the mounting bolt111and one end of the bolt holder113are joined by insert molding. A prescribed joining strength of the joint between the mounting bolt111and the bolt holder113is secured by forming a width across flat shank111a(seeFIG. 3) on one end of the mounting bolt111and by inserting an insert bolt112into the joint. The mounting bolt111has a threaded part111bon the other end. The side grip100(the grip body110) is mounted to the power tool by threadably engaging the threaded part111bwith a threaded hole of a body housing of the power tool.

The bolt holder113is a linearly extending rod-like member having a predetermined length and has a circular large-diameter shank114, a rod-like part115having a cross-shaped section and a circular small-diameter shank116. The large-diameter shank114, the rod-like part115and the small-diameter shank116are integrally and coaxially formed. Specifically, as shown inFIG. 2, the large-diameter shank114is formed on the tip side (the threaded part111bside) of the mounting bolt111with respect to the rod-like part115in the longitudinal direction of the bolt holder113, and the rod-like part115is formed between the large-diameter shank114and the small-diameter shank116. The large-diameter shank114has a flange114aextending outward (in the radial direction) on its end in the longitudinal direction. Further, an arcuate engagement groove114bis formed in an outer periphery of the large-diameter shank114on the side opposite to the flange114ain the longitudinal direction. Further, as shown inFIGS. 1 and 4, a plurality of (four in this embodiment) radially protruding rib-shaped projections114care formed contiguously to the back of the flange114aat prescribed intervals in the circumferential direction on the outer surface of the large-diameter shank114. As shown inFIG. 1, the projections114cextend from the back of the flange114asubstantially to a middle region of the large-diameter shank114in the longitudinal direction. As shown inFIG. 5, the rod-like part115is formed by plate-like members115aarranged in a cross shape.

As shown inFIGS. 1 and 2, an end cap117having a circular section is fitted on the small-diameter shank116. As shown inFIG. 2, the end cap117has a flange117aextending outward (in the radial direction) on its end in the longitudinal direction. Further, an arcuate engagement groove117bis formed in an outer periphery of the end cap117on the side opposite to the flange117ain the longitudinal direction. Further, as shown inFIG. 1, like in the large-diameter shank114, a plurality of (four in this embodiment) radially protruding rib-shaped projections117care formed contiguously to the back of the flange117aat prescribed intervals in the circumferential direction on the outer surface of the end cap117. The projections117cextend from the back of the flange117asubstantially to a middle region of the end cap117in the longitudinal direction.

As shown inFIGS. 1 and 2, the grip part120is a generally circular cylindrical member extending linearly with a prescribed length. The grip part120has a cylindrical part121, and a large-diameter cylindrical part122integrally formed on each end of the cylindrical part121and having a larger outside diameter than the cylindrical part121. As shown inFIG. 2, the large-diameter cylindrical part122has a stepped part122aformed on its connection to the cylindrical part121and having the same inside diameter as the cylindrical part121. An end region of the large-diameter cylindrical part122has a larger inside diameter than the cylindrical part121. Specifically, the large-diameter cylindrical part122has a step substantially in its middle in the longitudinal direction.

Further, as shown inFIG. 4, a plurality of (four in this embodiment) recesses122brecessed radially outward are formed at prescribed intervals in the circumferential direction in a region of the stepped part122ain an inside region of the large-diameter cylindrical part122of the grip part120. As shown inFIG. 5, a plurality of (four in this embodiment) inward protruding rib-shaped projections121aare formed at prescribed intervals in the circumferential direction on the inside of the cylindrical part121of the grip part120.

The grip part120is coaxially formed with the bolt holder113. A prescribed clearance is formed between the inner surface of the grip part120and the outer surface of the bolt holder113. As shown inFIG. 4, the projections114cof the large-diameter shank114of the bolt holder113are arranged in the middle of the recesses122bin the circumferential direction in one of the large-diameter cylindrical parts122. Similarly, the projections117cof the end cap117are arranged in the middle of the recesses122bin the circumferential direction in the other large-diameter cylindrical part122. Further, as shown inFIG. 5, part of the rod-like part115of the bolt holder113is arranged between tip ends of the projections121aof the cylindrical part121in the circumferential direction.

By coaxially arranging the grip part120on the outside of the bolt holder113, a prescribed clearance is formed between the inner surface of the grip part120and the outer surface of the bolt holder113and between the inner surface of the grip part120and the outer surface of the end cap117. Specifically, as shown inFIGS. 1, 2 and 4, a first space S1is formed between the outer surface of the large-diameter shank114including the flange114a, the engagement groove114band the projections114c, and the inner surface of the one large-diameter cylindrical part122including the recesses122band the inner surface of the end region of the cylindrical part121. As shown inFIGS. 1 and 2, a second space S2is formed between the outer surface of the end cap117including the flange117a, the engagement groove117band the projections117c, and the inner surface of the other large-diameter cylindrical part122including the recesses122band the inner surface of the end region of the cylindrical part121. The first space S1and the second space S2are provided as a rubber arrangement space for the elastic rubber130. The first space S1and the second space S2are an example embodiment that corresponds to the “elastic element interposing region” in the present invention.

A third space S3is formed between the outer peripheral surface of the rod-like part115of the bolt holder113and the inner surface of the cylindrical part121including the projections121a. The third space S3is provided as a powder filling space for the powder140. The third space S3is an example embodiment that corresponds to the “powder filling region” in the present invention.

The first, second and third spaces S1, S2, S3are arranged side by side in the longitudinal direction (crossing the radial direction from the bolt holder113toward the grip part120) of the side grip100. The elastic rubber130is disposed in the first and second spaces S1, S2, and the powder140is disposed in the third space S3. The elastic rubber130disposed in the first space S1is shaped to correspond to the shape of the first space S1. Similarly, the elastic rubber130disposed in the second space S2is shaped to correspond to the shape of the second space S2.

Specifically, as shown inFIGS. 1, 2 and 4, the elastic rubber130disposed in the first space S1nearer to the mounting bolt111has a cylindrical part130ainterposed between the outer surface of the large-diameter shank114of the bolt holder113and the inner surface of the grip part120in the radial direction, a stepped part130binterposed between the flange114aof the large-diameter shank114and the stepped part122aof the large-diameter cylindrical part122of the grip part120in the longitudinal direction, and radially protruding parts130cinterposed between the projections114cof the large-diameter shank114and the recesses122bof the large-diameter cylindrical part122in the circumferential direction.

Further, as shown inFIGS. 1 and 2, the elastic rubber130disposed in the second space S2far from the mounting bolt111has a cylindrical part130ainterposed between the outer surface of the end cap117and the inner surface of the grip part120opposed to the outer surface of the end cap117in the radial direction, a stepped part130binterposed between the flange117aof the end cap117and the stepped part122aof the large-diameter cylindrical part122of the grip part120in the longitudinal direction, and radially protruding parts130cinterposed between the projections117cof the end cap117and the recesses122bof the large-diameter cylindrical part122in the circumferential direction.

When a force of moving the grip part120and the bolt holder113with respect to each other is applied to the grip part120and the bolt holder113, the elastic rubbers130disposed in the first space S1and the second space S2allow the relative movement of the grip part120and the bolt holder113by elastically deforming or mainly by compressively deforming in all of the radial, longitudinal and circumferential directions of the side grip100. Specifically, the grip part120is connected to the bolt holder113via the elastic rubbers130such that the grip part120can move with respect to the bolt holder113in the three directions, or the radial, longitudinal and circumferential directions of the side grip100.

When the protruding parts130cof the elastic rubber130interposed between the projections114cof the large-diameter shank114and the recesses122bof the large-diameter cylindrical part122and the protruding parts130cof the elastic rubber130interposed between the projections117cof the end cap117and the recesses122bof the large-diameter cylindrical part122are compressively deformed, the grip part120is prevented from rotating with respect to the bolt holder113in the circumferential direction. Thus, the projections114c,117c, the recesses122band the protruding parts130cof the elastic rubbers130form the “rotation stopper” in the present invention.

The elastic rubber130disposed in the first space S1has an engagement part130dformed on the inner circumferential surface of the cylindrical part130aand engaged with the groove114bof the large-diameter shank114, so that relative movement of the elastic rubber130and the large-diameter shank114in the longitudinal direction is prevented. Similarly, the elastic rubber130disposed in the second space S2has an engagement part130dformed on the inner circumferential surface of the cylindrical part130aand engaged with the engagement groove117bof the end cap117, so that relative movement of the elastic rubber130and the end cap117in the longitudinal direction is prevented. Further, the grip part120is arranged between the stepped parts130bof the both elastic rubbers130in the longitudinal direction, so that the elastic rubbers130and the grip part120are prevented from moving with respect to each other in the longitudinal direction.

The third space S3is filled with powders140. The powders140are an assembly of powders or granules. For example, powders such as sand, cement and wheat flour, and magnetic fine powder or toner are suitably used.

The powders140in the third space S3are interposed between the inner surface of the cylindrical part121of the grip part120and the outer surface of the rod-like part115of the bolt holder113opposed to the inner surface of the cylindrical part121, and as shown inFIG. 1, interposed between ends of the rib-shaped projections121aof the cylindrical part121in the extending direction and an inner end of the large-diameter shank114in the longitudinal direction. Further, as shown inFIG. 5, the powders140are interposed between side surfaces of the projections121aof the cylindrical part121and the plate-like members115aof the rod-like part115of the bolt holder113opposed to the side surfaces of the projections121a. Specifically, the powders140are disposed (filled) between the bolt holder113and the grip part120in the three directions, or the radial, longitudinal and circumferential directions of the side grip100. The projections121a, the plate-like members115aand the powders140interposed between the projections121aand the plate-like members115aprevent the grip part120from rotating with respect to the bolt holder113in the circumferential direction. The projections121a, the plate-like members115aand the powders140interposed therebetween form the “rotation stopper” in the present invention.

The powders140are filled when the side grip100is assembled. Specifically, the grip part120is moved in the longitudinal direction toward the bolt holder113with the elastic rubber130fitted on the large-diameter shank114in advance, and one end of the grip part120is fitted onto the elastic rubber130around the large-diameter shank114. Subsequently, the powders140are filled from the other end of the grip part120. After filling the powders140, the end cap117having the elastic rubber130fitted thereon in advance is inserted into the other end part of the grip part120and fitted in the grip part120and on the small-diameter shank116of the bolt holder113. Thereafter, the end cap117is fixed by threadably engaging a set screw (not shown) with a threaded hole116aof the small-diameter shank116through a through hole117dof the end cap117. Further, a clearance between the outer circumferential surface of the cylindrical part130aof the elastic rubber130and the inner circumferential surface of the cylindrical part121of the grip part120is sealed by a sealing material such as an adhesive, so that the powders140are prevented from flowing out of the side grip.

The side grip100of the first embodiment is applied to an electric grinder150shown inFIG. 11or a hammer drill160shown inFIG. 12as a hand-held power tool.

As shown inFIG. 11, the electric grinder150has a generally cylindrical body housing151, and a grinding wheel (not shown) as an accessory tool is attached to a front end region (on the left as viewed inFIG. 11) of the body housing151in the longitudinal direction. The body housing151is an example embodiment that corresponds to the “tool body” in the present invention. A region of the body housing151on the side opposite to the accessory tool side is set as a main grip part153to be held by a user. The side grip100is attached to the front end region side of the body housing151. Specifically, a grip mounting part having a threaded hole is provided on the front end region side of the body housing151, and the side grip100is attached to the electric grinder150by threadably engaging the threaded part111bof the mounting bolt111with the threaded hole of the grip mounting part. The user holds the main grip part153and the side grip100and performs a grinding operation.

As shown inFIG. 12, in the hammer drill160, a hammer bit (not shown) as the accessory tool is mounted to the front end region of a body housing161. A hand grip163is provided as a main handle on the side of the body housing161opposite to the hammer bit and extends in a direction crossing the longitudinal direction of the body housing161. The body housing161is an example embodiment that corresponds to the “tool body” in the present invention. The side grip100is attached to the front end region side of the body housing161via a detachable ring-like mounting member165. Specifically, the side grip100is attached by threadably engaging the threaded part111bof the mounting bolt111with a threaded hole of the ring-like mounting member165. The user holds the hand grip163and the side grip100and performs a drilling operation.

When performing an operation with the electric grinder150or the hammer drill160while holding the side grip100, the grip body110vibrates together with the body housing151or161. In the side grip100, the elastic rubber130interposed between the bolt holder113of the grip body110and the grip part120elastically deforms according to the vibration of the bolt holder113. As a result, transmission of vibration to the grip part120is reduced.

Specifically, as for vibration in the radial direction crossing the longitudinal direction of the side grip100(vibration in the longitudinal direction of the body housing151or161), transmission of vibration to the grip part120is reduced by compressive deformation of the cylindrical part130aof the elastic rubber130interposed between the large-diameter shank114and the grip part120and between the end cap117and the grip part120. Further, as for vibration in the longitudinal direction of the side grip100, transmission of vibration to the grip part120is reduced by compressive deformation of the stepped part130bof the elastic rubber130interposed between the flange114aof the large-diameter shank114and the stepped part122aof the large-diameter cylindrical part122and between the flange117aof the end cap117and the stepped part122aof the large-diameter cylindrical part122. As for vibration in the circumferential direction around the axis of the side grip100, transmission of vibration to the grip part120is reduced by compressive deformation of the protruding parts130cof the elastic rubber130interposed between the projections114cof the large-diameter shank114and the recesses122bof the grip part120and between the projections117cof the end cap117and the recesses122bof the grip part120.

The powders140contact each other and repeat micro vibration in response to vibration of the grip body110which is caused by vibration of the body housing151or161. At this time, kinetic energy of vibration of the body110is consumed by frictional resistance between the powders, so that vibration is reduced. As a result, transmission of vibration to the grip part120is reduced. Specifically, in the side grip100, the effect of reducing transmission of vibration is enhanced by reducing the hardness or the spring constant of the elastic rubber130, and transmission of vibration is also reduced by flow of the powders140. Thus, transmission of vibration caused in the bolt holder113is reduced by the elastic rubber130and the powders140. As a result, transmission of vibration from the bolt holder113to the grip part120is effectively reduced.

The acceleration generated when a user holds the side grip100and actuates the electric grinder150or the hammer drill160is smaller than the acceleration of vibration caused in the body housing151or161during operation. Therefore, the power inputted into the grip part120held by the user is received by the powders140. Thus, the powders140serve to enhance the rigid feeling of the connection between the bolt holder113and the grip part120and prevent wobble of the grip part120. As a result, operability for the user holding the grip part120is improved. With the structure in which the powders140are disposed between the bolt holder113including the end cap117and the grip part120in the three directions, or the radial, longitudinal and circumferential directions of the side grip100, the powders140effectively act upon the user's power inputted into the grip part120in any of the three directions.

As described above, the side grip100of the first embodiment ensures the vibration-proof property of the grip part120and improves the operability for operating the electric grinder150or the hammer drill160.

Further, according to the first embodiment, the entire region of the elastic rubber130in the circumferential direction is interposed between the inner surface of the cylindrical part121of the grip part120and the outer surface of the large-diameter shank114of the bolt holder113, and between the inner surface of the cylindrical part121of the grip part120and the outer surface of the end cap117. Further, the entire region of the powders140in the circumferential direction is interposed between the inner surface of the cylindrical part121of the grip part120and the outer surface of the rod-like part115of the bolt holder113. Therefore, the elastic rubber130and the powders140reduce vibration which is caused in a plurality of directions and transmitted from the body housing151or161to the grip part120via the grip body110in the radial direction of the grip part120. In the case of the electric grinder150shown inFIG. 11, for example, the longitudinal direction (the vertical direction inFIG. 11) and the vertical direction (a direction perpendicular to the paper plane ofFIG. 11) of the electric grinder150correspond to the “first direction” and the “second direction”, respectively, in the present invention. In the case of the hammer drill160shown inFIG. 12, the longitudinal direction (the horizontal direction inFIG. 12) and the transverse direction (a direction perpendicular to the paper plane ofFIG. 12) of the hammer drill160correspond to the “first direction” and the “second direction”, respectively, in the present invention.

Further, according to the first embodiment, the elastic rubber130is interposed between the projections114cof the large-diameter shank114and the recesses122bof the large-diameter cylindrical part122and between the projections117cof the end cap117and the recesses122bof the large-diameter cylindrical part122. Further, the powders140are interposed between the projections121aof the cylindrical part121and the plate-like members115aof the rod-like part115. With this structure, the grip part120is prevented from rotating with respect to the bolt holder113in the circumferential direction. When attaching the side grip100to the body housing151or161by threadably engaging the threaded part111bof the mounting bolt111with the threaded hole of the body housing151or161of the electric grinder150or the hammer drill160, rotation of the grip part120is reliably transmitted to the threaded part111b. Therefore, attachment and detachment of the side grip100can be reliably achieved.

In the first embodiment, when the grip mounting part of the electric grinder150has a different shape from the grip mounting part of the hammer drill160, the length or diameter of the mounting bolt111is adjusted in advance to correspond to the shapes of the grip mounting parts.

Further, in the first embodiment, each of the elastic rubbers130and the powders140are arranged over the entire region of the bolt holder113in the circumferential direction around the axis of the bolt holder113, but the arrangement is not limited to this. For example, a plurality of the elastic rubbers130and/or the powders140may be arranged at prescribed intervals in the circumferential direction of the bolt holder113.

Further, in the first embodiment, the elastic rubber130and the powders140are arranged side by side in a direction (the longitudinal direction of the side grip100) crossing a direction (the radial direction) from the bolt holder113toward the grip part120, but the arrangement is not limited to this. For example, the elastic rubber130and the powders140may be arranged side by side in the direction (the radial direction) from the bolt holder113toward the grip part120.

(Second Embodiment of the Invention)

The side grip100according to a second embodiment of the present invention is now described with reference toFIGS. 6 to 10. The second embodiment is different from the first embodiment in the manner of filling the powders140. The powders140are filled and sealed in advance in a tube-like bag141formed of a flexible material such as rubber, cloth and vinyl. The bag141filled with the powders140is disposed in the space between the inner surface of the cylindrical part121of the grip part120and the outer surface of the rod-like part115of the bolt holder113. In the other points, this embodiment has substantially the same structure as the first embodiment. Components or elements in the second embodiment which are substantially identical to those in the first embodiment are given like numerals as in the first embodiment and will not be described. The tube-like bag141is an example embodiment that corresponds to the “bag” in the present invention.

As shown inFIG. 10, the rod-like part115of the bolt holder113is generally cylindrically formed and has a plurality of (four in this embodiment) housing grooves115bhaving an arcuate section and extending in parallel to the longitudinal direction of the rod-like part115. The housing grooves115bare configured as powder arrangement space and formed at prescribed intervals in the circumferential direction of the rod-like part115. The housing groove115bis an example embodiment that corresponds to the “powder filling region” in the present invention. One end of each of the housing grooves115bon the large-diameter shank114side in the longitudinal direction is closed by the large-diameter shank114. The other end of the housing groove115bon the small-diameter shank116side in the longitudinal direction is open in the longitudinal direction. The bag141filled with the powders140is generally cylindrically formed and is inserted into each of the housing grooves115bfrom the open end on the small-diameter shank116side and held therein.

The housing groove115bhas a generally semi-circular arc shape. Therefore, as shown inFIG. 10, the bag141disposed in the housing groove115bis held so as to partially protrude on the outer surface of the rod-like part115from the housing groove115b. The part of the bag141protruding from the rod-like part115is held in contact with the inner surface of the cylindrical part121of the grip part120.

In the final process of assembling the side grip100, as shown inFIG. 7, the bag141filled with the powders140is disposed in the space between the inner surface of the cylindrical part121of the grip part120and the outer surface of the rod-like part115of the bolt holder113by inserting and fitting the end cap117on which the elastic rubber130is fitted in advance into the other end part of the grip part120. The end cap117is fixed to the bolt holder113by threadably engaging a set screw (not shown) with the threaded hole116aof the small-diameter shank116through the through hole117dof the end cap117.

Like in the first embodiment, the side grip100according to the second embodiment is mounted to an electric grinder150shown inFIG. 11or a hammer drill160shown inFIG. 12as a hand-held power tool. Like in the first embodiment, the side grip100of this embodiment ensures the vibration-proof property of the grip part120and improves the operability for operating the electric grinder150or the hammer drill160.

Further, according to the second embodiment, the powders140filled in the bag141formed of a flexible material such as rubber, cloth and vinyl are inserted into the housing grooves115bof the rod-like part115. Therefore, the powders140can be easily arranged in the space between the inner surface of the cylindrical part121of the grip part120and the outer surface of the rod-like part115of the bolt holder113. Therefore, the assembling operation of the side grip100is simplified.

In the second embodiment, the powders140are arranged at prescribed intervals in the circumferential direction of the bolt holder113, but the arrangement is not limited to this. For example, the powders140may be arranged continuously over the entire region of the bolt holder113in the circumferential direction.

(Third Embodiment of the Invention)

A third embodiment of the present invention is now described with reference toFIGS. 13 to 18. In the third embodiment, the present invention is applied to a handle of a bush cutter. As shown inFIG. 13, a bush cutter1includes an operation rod2, a power unit3mounted to one end of the operation rod2, a cutting unit4provided on the other end of the operation rod2, and a generally U-shaped handle7mounted to a middle of the operation rod2and protruding in a direction crossing the extending direction of the operation rod2. A cutting blade5as an accessory tool is rotatably held by the cutting unit4. The power unit3has an engine (not shown) for driving the cutting blade5. As shown inFIG. 14, the output of the engine is transmitted as rotating motion to the cutting blade5via a rotary shaft9extending within the operation rod2. The operation rod2, the power unit3, the cutting unit4and the handle7are example embodiments that correspond to the “operation rod”, the “driving unit”, the “cutting unit” and the “handle”, respectively, in the present invention.

As shown inFIGS. 14 and 15, two support parts21,23are provided on the operation rod2with prescribed spacing in the longitudinal direction of the operation rod2in order to mount the handle7onto the operation rod2. The support parts21,23are formed as flange-like members. The support part21formed on the end of the operation rod2on the power unit3side also serves as a connection member for connecting the operation rod2to the power unit3.

As shown inFIG. 14, the handle7mainly includes a grip part71to be held by a user, an elastic rubber80and powders90. The handle7has a cylindrical member73having a generally circular section and integrally connected to the grip part71. The grip part71is an example embodiment that corresponds to the “grip” in the present invention. As shown inFIG. 15, the cylindrical member73is coaxially disposed on the outside of the operation rod2between the support parts21,23of the operation rod2. A flange-like connecting part75is formed on one end of the cylindrical member73in the longitudinal direction and opposed to the support part21of the operation rod2in the longitudinal direction. Further, a flange-like connecting part77is formed on the other end of the cylindrical member73and opposed to the other support part23of the operation rod2in the longitudinal direction. The connecting parts75,77are connected to the support parts21,23, respectively, via a plurality of (four each in this embodiment) elastic rubbers80disposed at prescribed intervals around the center line of the operation rod2at positions offset from the center line. The elastic rubber80is an example embodiment that corresponds to the “elastic element” in the present invention.

As shown inFIG. 15, a plurality of cylindrical recesses75a,77aare formed at prescribed intervals in the circumferential direction of the cylindrical member73in the surfaces of the connecting parts75,77of the cylindrical member73which are opposed to the support parts21,23. Further, cylindrical shaft-like projections21a,23aare formed at prescribed intervals around the axis of the operation rod2on the surfaces of the support parts21,23which are opposed to the connecting parts75,77, so as to correspond to the recesses75a,77a.

As shown inFIGS. 16 to 18, each of the elastic rubbers80has a cylindrical shape having a mounting hole81in the center. The powders90are filled and sealed in the elastic rubber80. Specifically, the elastic rubber80has a cylindrical space S5continuously extending in the circumferential direction of the elastic rubber80and filled with the powders90. The cylindrical space S5of the elastic rubber80and the powder90are example embodiments that correspond to the “powder filling region” and the “powder”, respectively, according to the present invention. As shown inFIG. 15, the elastic rubbers80are fixedly fitted in the cylindrical recesses75a,77aof the connecting parts75,77. Further, the projections21a,23aof the support parts21,23are fixedly fitted in the mounting holes81of the elastic rubbers80. Therefore, the elastic rubbers80and the powders90are arranged along a direction (the longitudinal direction of the operation rod2) from the support parts21,23toward the cylindrical member73. A cylindrical space S4between the cylindrical recesses75a,77aof the connecting parts75,77and the projections21a,23aof the support parts21,23is an example embodiment that corresponds to the “elastic element interposing region” in the present invention. Further, the inner circumferential surface of the mounting hole81of the elastic rubber80is an example embodiment that corresponds to the “connection part” in the present invention.

As shown inFIG. 15, the support part21of the operation rod2close to the power unit3is formed integrally with the operation rod2. The support part23far from the power unit3is formed separately from the operation rod2. After the cylindrical member73of the handle7is assembled onto the operation rod2, the support part23is mounted onto the operation rod2. Further, the grip part71to be held by a user is connected to the connecting part77of the cylindrical member73far from the power unit3.

During bush cutting of weeds or small-diameter woods by the bush cutter1, the operation rod2vibrates by driving of the power unit3or cutting operation of the cutting unit4. The elastic rubbers80reduce transmission of vibration to the grip part71by elastically deforming in response to the vibration of the operation rod2. Specifically, as for vibration in radial directions crossing the longitudinal direction of the operation rod2or in the vertical and transverse directions, and vibration in a rotational direction around the axis of the operation rod2, transmission of vibration to the grip part71is reduced by elastic deformation (compressive deformation) of regions of the elastic rubbers80which are interposed between the inner circumferential walls of the recesses75a,77aof the connecting parts75,77and the outer circumferential surfaces the projections21a,23aof the support parts21,23, respectively. Further, as for vibration in the longitudinal direction of the operation rod2or in the longitudinal direction, transmission of vibration to the grip part71is reduced by elastic deformation (compressive deformation) of regions of the elastic rubbers80which are interposed between the bottoms of the recesses75a,77aand the side surfaces of the support parts21,23opposed to the bottoms of the recesses75a,77a, respectively. The radial direction crossing the longitudinal direction of the operation rod2and the longitudinal direction of the operation rod2are example embodiments that correspond to the “first direction” and the “second direction”, respectively, in the present invention.

The powders90in the elastic rubber80contact each other and repeat micro vibration in response to vibration of the operation rod2. At this time, kinetic energy of vibration of the operation rod2is consumed by frictional resistance between the powders, so that vibration is reduced. As a result, transmission of vibration to the grip part71is reduced. Thus, transmission of vibration caused in the operation rod2is reduced by the elastic rubbers80and the powders90. As a result, transmission of vibration from the operation rod2to the handle7is effectively reduced.

The acceleration generated when a user holds the grip part71and actuates the bush cutter1is smaller than the acceleration of vibration caused in the operation rod2during bush cutting operation. Therefore, the power inputted into the handle7held by the user is received by the powders90. Thus, the powders90serve to enhance the rigid feeling of the connection between the operation rod2and the cylindrical member73and prevent wobble of the cylindrical member73. As a result, operability for the user holding the handle7is improved. With the structure in which the powders90are filled in the elastic rubbers80and disposed between the support parts21,23and the connecting parts75,77in the three directions, or the longitudinal direction of the operation rod2, the radial direction crossing the longitudinal direction, and the circumferential direction around the axis of the operation rod2, the powders90effectively act upon the user's power inputted into the handle7in any of the three directions.

As described above, the handle7of the third embodiment ensures its vibration-proof property and improves the operability for operating the bush cutter1.

In the third embodiment, the elastic rubbers80are arranged at prescribed intervals in the circumferential direction of the operation rod2, but the arrangement is not limited to this. For example, the elastic rubbers80may be continuously arranged over the entire region of the operation rod2in the circumferential direction.

(Fourth Embodiment of the Invention)

A fourth embodiment of the present invention is now described with reference toFIGS. 19 and 20. In the fourth embodiment, the present invention is applied to a main handle of a hammer drill. As shown inFIGS. 19 and 20, a hammer drill200mainly includes a body housing201that forms an outer shell of the hammer drill200, a handgrip209as a main handle to be held by a user, and a tool holder250for holding a hammer bit219. The body housing201, the handgrip209and the hammer bit219are example embodiments that correspond to the “tool body”, the “handle” and the “tool bit”, respectively, in the present invention.

In the fourth embodiment, for the sake of convenience, the hammer bit219side is defined as “the front” and the handgrip209side is defined as “the rear”, in the axial direction of the hammer bit219(the longitudinal direction of the body housing201). Further, the upper side inFIG. 19is defined as “the upper side” and the lower side inFIG. 19is defined as “the lower side”.

The body housing201is formed by connecting a pair of generally symmetric housing halves together and houses an electric motor210, a motion converting mechanism, a power transmitting mechanism and a striking mechanism (not shown). The electric motor210is arranged such that its rotation axis is in parallel to the axial direction of the hammer bit219.

The handgrip209is connected to the body housing201in a rear region on the side opposite to the hammer bit219. The handgrip209extends in a vertical direction crossing the axial direction of the hammer bit219. A trigger209ais provided in the handgrip209, and when the user operates the trigger209a, the electric motor210is driven.

When the electric motor210is driven, rotation of the electric motor210is converted into linear motion by the motion converting mechanism and then transmitted to the hammer bit219as linear motion in the axial direction via the striking mechanism. Thus, the hammer bit219is struck. Further, the hammer bit219is caused to rotate via the power transmitting mechanism which is driven by the electric motor210. Therefore, the hammer bit219performs a hammer drill operation on a workpiece by hammering motion in the axial direction and rotating motion in the circumferential direction.

As shown inFIG. 19, the handgrip209mainly includes a vertically extending grip part223formed on the rear end of the body housing201to be held by a user, an elastic rubber230and powders240. The grip part223has a generally cylindrical housing part221having an open front. The grip part223is an example embodiment that corresponds to the “grip” in the present invention. The cylindrical housing part221is arranged to cover a rear part (also referred to as a motor housing) of the body housing201which houses the electric motor210. The motor housing is generally cylindrically shaped. The cylindrical housing part221is arranged to be movable with respect to the motor housing in the axial direction of the hammer bit219.

The grip part223of the handgrip209extends downward in a prescribed length from the rear end part of the cylindrical housing part221. The grip part223has an extending end formed as a free end. The handgrip209having the grip part223which is configured as described above is also referred to as a pistol type handle.

As shown inFIGS. 19 and 20, a plurality of (four in this embodiment) vibration-proofing elastic rubbers230are disposed between an outer surface of the body housing201and an inner surface of the cylindrical housing part221at prescribed intervals around the rotation axis of the electric motor210(in the circumferential direction of the cylindrical housing part221). Thus, the cylindrical housing part221is connected to the body housing201via the four elastic rubbers230disposed around the rotation axis of the electric motor210. The elastic rubbers230and the cylindrical housing part221are example embodiments that correspond to the “elastic element” and the “connecting region”, respectively, in the present invention.

As shown inFIG. 20, the four elastic rubbers230are arranged symmetrically with respect to a vertical line crossing the rotation axis of the electric motor210. Each of the elastic rubbers230is held between an outer rubber receiver221aformed in the cylindrical housing part221and having a generally hemispherical concave surface and an inner rubber receiver201aformed in the body housing201and having a generally hemispherical concave surface. A space S6defined by the generally hemispherical concave surface of the outer rubber receiver221aand the generally hemispherical concave surface of the inner rubber receiver201ais an example embodiment that corresponds to the “elastic element interposing region” in the present invention. Further, a part of the outer surface of the elastic rubber230which is held in contact with the inner rubber receiver201aof the body housing201is an example embodiment that corresponds to the “connection part” in the present invention.

In the connection part structure of connecting the cylindrical housing part221and the body housing201via the four elastic rubbers230, as for the upper right and left connection parts with respect to the horizontal axis crossing the rotation axis of the electric motor210, the opposed surfaces of the outer rubber receivers221aand the inner rubber receivers201aare formed to form a generally inverted-V shape as viewed from the handgrip209side (from behind). As for the lower right and left connection parts, the opposed surfaces of the outer rubber receivers221aand the inner rubber receivers201aare formed to form a generally V shape as viewed from the handgrip209side (from behind). Specifically, the opposed surfaces of the outer rubber receiver221aand the inner rubber receiver201aare configured to be parallel to the axial direction of the hammer bit219and inclined about 45 degrees in the horizontal (transverse) and vertical directions crossing the axial direction. With this structure, shearing force mainly acts upon the elastic rubbers230in the axial direction, and compression force mainly acts upon them in the directions crossing the axial direction.

A plurality of powder filling spaces S7are formed between the outer circumferential surface of the body housing201and the inner circumferential surface of the cylindrical housing part221behind the connection parts formed by the elastic rubbers230. The spaces S7are filled with powders240. Thus, the elastic rubbers230and the powders240are arranged side by side in a direction crossing a direction from the body housing201toward the cylindrical housing part221. The space S7and the powder240are example embodiments that correspond to the “powder filling region” and the “powder”, respectively, in the present invention. The powder filling spaces S7may be formed continuously over the entire region in the circumferential direction, or they may be formed at prescribed intervals in the circumferential direction. The powders240are filled and sealed in advance in a bag241formed of a flexible material such as rubber, cloth and vinyl, and the bag241filled with the powders240is disposed in each of the spaces S7.

The powders240disposed in the space S7is interposed between a rib-like projection201bformed on the outer circumferential surface of the body housing201and a rib-like projection221bformed on the inner circumferential surface of the cylindrical housing part221in the axial direction of the hammer bit219and also interposed between the outer circumferential surface of the body housing201and the inner circumferential surface of the cylindrical housing part221in the radial direction crossing the axial direction.

During hammer drill operation by the hammer drill200, vibration is caused in the body housing201. The elastic rubbers230disposed between the body housing201and the cylindrical housing part221of the handgrip209reduce transmission of vibration to the handgrip209by elastically deforming in response to vibration of the body housing201. Specifically, as for vibration in the axial direction of the hammer bit219, transmission of vibration to the handgrip209is reduced by shearing deformation of the elastic rubbers230in the axial direction of the hammer bit219between the outer rubber receivers221aand the inner rubber receivers201a. Further, as for vibration in directions crossing the axial direction, transmission of vibration to the handgrip209is reduced by compressive deformation of the elastic rubbers230in the vertical or transverse direction crossing the axial direction of the hammer bit219between the outer rubber receivers221aand the inner rubber receivers201a. The axial direction of the hammer bit219and the direction crossing the axial direction are example embodiments that correspond to the “first direction” and the “second direction”, respectively, in the present invention.

The powders240contact each other and repeat micro vibration in response to vibration of the body housing201. At this time, kinetic energy of vibration of the body housing201is consumed by frictional resistance between the powders, so that vibration is reduced. As a result, transmission of vibration to the handgrip209is reduced. Thus, transmission of vibration from the body housing201to the handgrip209is effectively reduced.

The acceleration generated when a user holds the handgrip209and actuates the hammer drill200is smaller than the acceleration of vibration caused in the body housing201during hammer drill operation. Therefore, the power inputted into the handgrip209held by the user is received by the powders240. Thus, the powders240serve to enhance the rigid feeling of the connection between the body housing201and the cylindrical housing part221and prevent wobble of the cylindrical housing part221. As a result, operability for the user holding the handgrip209is improved. Thus, the handgrip209of the fourth embodiment ensures its vibration-proof property and improves the operability for operating the hammer drill200.

(Fifth Embodiment of the Invention)

A fifth embodiment of the present invention is now described with reference toFIGS. 21 and 22. In the fifth embodiment, the present invention is applied to a main handle of a hammer drill. As shown inFIG. 21, a hammer drill300mainly includes a body housing301that forms an outer shell of the hammer drill300, a handgrip309as a main handle to be held by a user, and a tool holder350for holding a hammer bit319. The body housing301, the handgrip309and the hammer bit319are example embodiments that correspond to the “tool body”, the “handle” and the “tool bit”, respectively, in the present invention.

In the fifth embodiment, for the sake of convenience, the hammer bit319side is defined as “the front” and the handgrip309side is defined as “the rear”, in the axial direction of the hammer bit319(the longitudinal direction of the body housing301). Further, the upper side inFIG. 21is defined as “the upper side” and the lower side inFIG. 21is defined as “the lower side”.

The body housing301is formed by connecting a pair of generally symmetric housing halves together and houses an electric motor310, a motion converting mechanism311, a power transmitting mechanism313and a striking mechanism315. The electric motor310is arranged such that its rotation axis extends in a direction crossing the axial direction of the hammer bit319.

The handgrip309is disposed in a rear region of the hammer drill300on the side opposite to the hammer bit319. The handgrip309extends in a vertical direction crossing the axial direction of the hammer bit319. Ends of the handgrip309in the vertical direction are connected to the body housing301. A trigger309ais provided in the handgrip309, and when the user operates the trigger309a, the electric motor310is driven.

When the electric motor310is driven, rotation of the electric motor310is converted into linear motion by the motion converting mechanism311and then transmitted to the hammer bit319as linear motion in the axial direction via the striking mechanism315. Thus, the hammer bit319is struck. Further, the hammer bit319is caused to rotate via the power transmitting mechanism313which is driven by the electric motor310. Therefore, the hammer bit319performs a hammer drill operation on a workpiece by hammering motion in the axial direction and rotating motion in the circumferential direction.

As shown inFIG. 21, the handgrip309mainly includes a grip part309A extending in the vertical direction crossing the axial direction of the hammer bit319, an elastic rubber330and powders340. The grip part309A has an upper connecting region309B extending forward from an upper end of the grip part309A and connected to the body housing301, and a lower connecting region309C extending forward from a lower end of the grip part309A and connected to the body housing301. The grip part309A is an example embodiment that corresponds to the “grip” in the present invention.

A compression coil spring320is disposed between a front part of the upper connecting region309B and a rear upper part of the body housing301. The compression coil spring320is arranged such that the working direction of its spring force substantially coincides with the direction of vibration which is generated in the axial direction of the hammer bit319during hammer drill operation. Specifically, the compression coil spring320is arranged to extend in the axial direction of the hammer bit319. The compression coil spring320is arranged above the axis of the hammer bit319. One end of the compression coil spring320in the longitudinal direction is supported by a body-side spring receiver320aformed in the body housing301, and the other end is supported by a grip-side spring receiver320bformed in the upper connecting region309B. Thus, the upper connecting region309B of the handgrip309is connected to the body housing301via the compression coil spring320and can move with respect to the body housing301in the axial direction of the hammer bit319. The compression coil spring320is covered by an extensible rubber dustproof cover321disposed between the body housing301and the upper connecting region309B. The upper connecting region309B is an example embodiment that corresponds to the “connecting region” in the present invention.

As shown inFIGS. 21 and 22, the lower connecting region309C is connected to a rear lower part of the body housing301via the elastic rubber330. The elastic rubber330and the lower connecting region309C are example embodiments that correspond to the “elastic element” and the “connecting region”, respectively, in the present invention. The elastic rubber330has a cylindrical shape having a circular hole330ain the center. The inside of the elastic rubber330is filled with the powders340. Specifically, as shown inFIG. 22, a plurality of arcuate spaces S9are formed in the elastic rubber330in two rows in the radial direction and at prescribed intervals in the circumferential direction of the elastic rubber330. At least one end of the space S9in the longitudinal direction of the elastic rubber330is open as a filling port for the powders340and closed after the powders340are filled in. The arcuate space S9and the powder340are example embodiments that correspond to the “powder filling region” and the “powder”, respectively, in the present invention.

The elastic rubber330filled with the powders340is disposed between a cylindrical outer rubber receiver331aformed in the rear lower part of the body housing301and a columnar inner rubber receiver331bcoaxially arranged within the outer rubber receiver331a. Thus, the elastic rubber330and the powders340are arranged side by side in a direction from the outer rubber receiver331atoward the columnar inner rubber receiver331b(the center). The outer rubber receiver331aand the inner rubber receiver331bare configured such that their longitudinal direction coincides with the transverse direction crossing the axial direction of the hammer bit319. Ends of the columnar inner rubber receiver331bin the longitudinal direction are fixedly supported by a front end part of the lower connecting region309C. A space S8defined between the outer rubber receiver331aand the inner rubber receiver331bis an example embodiment that corresponds to the “elastic element interposing region” in the present invention. Further, a part of the outer circumferential surface of the elastic rubber330which is held in contact with the cylindrical outer rubber receiver331ais an example embodiment that corresponds to the “connection part” in the present invention.

The elastic rubber330is fitted in the outer rubber receiver331a, and the outer circumferential surface of the elastic rubber330is received by the inner circumferential surface of the outer rubber receiver331a. The inner rubber receiver331bis fitted in the circular hole330aof the elastic rubber330, and the inner circumferential surface of the elastic rubber330is received by the outer circumferential surface of the inner rubber receiver331b. Thus, the lower connecting region309C of the handgrip309is connected to the body housing301via the elastic rubber330filled with the powders340and can move with respect to the body housing301in the axial direction of the hammer bit319.

During hammer drill operation by the hammer drill300, vibration is caused in the body housing301. The compression coil spring320disposed between the body housing301and the upper connecting region309B and the elastic rubber330disposed between the body housing301and the lower connecting region309C reduce transmission of vibration to the handgrip309by elastically deforming in response to vibration of the body housing301. Specifically, as for vibration in the axial direction of the hammer bit319, transmission of vibration to the handgrip309is reduced by compressive deformation of the elastic rubber330in the axial direction of the hammer bit319between the outer rubber receiver331aand the inner rubber receiver331b. Further, as for vibration in directions crossing the axial direction, transmission of vibration to the handgrip309is reduced by compressive deformation of the elastic rubber330in the vertical or transverse direction crossing the axial direction of the hammer bit319between the outer rubber receiver331aand the inner rubber receiver331b. The axial direction of the hammer bit319and the direction crossing the axial direction are example embodiments that correspond to the “first direction” and the “second direction”, respectively, in the present invention.

The powders340filled in the inside of the elastic rubber330contact each other and repeat micro vibration in response to vibration of the body housing301. At this time, kinetic energy of vibration of the body housing301is consumed by frictional resistance between the powders, so that vibration is reduced. As a result, transmission of vibration to the handgrip309is reduced. Thus, transmission of vibration from the body housing301to the handgrip309is effectively reduced.

The acceleration generated when a user holds the handgrip309and actuates the hammer drill300is smaller than the acceleration of vibration caused in the body housing301during hammer drill operation. Therefore, the power inputted into the handgrip309held by the user is received by the powders340. Thus, the powders340serve to enhance the rigid feeling of the connection between the body housing301and the lower connecting region309C and prevent wobble of the lower connecting region309C. As a result, operability for the user holding the handgrip309is improved. Thus, the handgrip309of the fifth embodiment ensures its vibration-proof property and improves the operability for operating the hammer drill300.

In the fifth embodiment, the powders340are arranged at a plurality of positions in the inside of the elastic rubber330, but the arrangement is not limited to this. For example, the powders340may be arranged continuously over the entire region of the elastic rubber330in the circumferential direction. Further, the elastic rubber330has a cylindrical shape, but it may have a quadrangular prism shape. In this case, a front half of the quadrangular prism is supported by the body housing301, and a rear half of the quadrangular prism is supported by the lower connecting region309C. Further, the elastic rubber330filled with the powders340may be disposed in the upper connecting region309B.

In the above-described embodiments, the powders are described as being directly disposed between the “connection part” and the “grip” in this invention, or disposed between the elastic rubbers, but may be disposed otherwise. For example, the present invention also suitably includes the manner in which the powders are disposed between the elastic rubber and the “connection part”, and the manner in which the powders are disposed between the elastic rubber and the “grip”.

In the above-described embodiments, the electric grinder150, the bush cutter1and the hammer drills160,200,300are explained as representative examples of the power tool, but the present invention is not limited to them. For example, the present invention may also be applied to an auxiliary handle or a main handle of a reciprocating saw or a hammer.

In view of the nature of the present invention, the following features can be provided.

The power tool as defined in claim8, wherein the powder filling region is arranged between the elastic element and the connection part, between the elastic element and the grip, between the connection part and the grip, or between the elastic elements.

According to aspect 1, the powders are rationally arranged to cope with vibrations in a plurality of directions.

The power tool as defined in claim10, wherein the elastic element is directly connected to the tool body.

According to aspect 2, the elastic element is rationally connected to the tool body by direct connection.

(Correspondences Between the Features of the Embodiments and the Features of the Invention)

Correspondences between the features of the embodiments and the features of the invention are as follows. The above-described embodiments are representative examples for embodying the present invention, and the present invention is not limited to the structures that have been described as the representative embodiments.

The grip body110, a contact part of the elastic rubber80with the projection21a, a contact part of the elastic rubber230with the inner rubber receiver201a, a contact part of the elastic rubber330with the outer rubber receiver331aare example embodiments that correspond to the “connection part” according to the present invention.

The grip parts120,71,223,309A are example embodiments that correspond to the “grip” in the present invention.

The elastic rubbers130,80,230,330are example embodiments that correspond to the “elastic element” in the present invention.

The powders140,90,240,340are example embodiments that correspond to the “powder” according to the present invention.

The first space S1, the second space S2, the cylindrical space S4and the space S6and the space S8are example embodiments that correspond to the “elastic element interposing region” in the present invention.

The third space S3, the housing groove115b, the cylindrical space S5, the space S7and the space S9are example embodiments that correspond to the “powder filling region” in the present invention.

The projections114c,117c, the recesses122band the protruding parts130cof the elastic rubber130which are disposed between the projections114c,117cand the recesses122bare example embodiments that correspond to the “rotation stopper” in the present invention.

The powder140between the projections121aand the plate-like member115ais an example embodiment that corresponds to the “rotation stopper” in the present invention.

The tube-like bag141is an example embodiment that corresponds to the “bag” in the present invention.

The body housings151,161, the operation rod2, the body housings201,301are example embodiments that correspond to the “tool body” in the present invention.

The operation rod2is an example embodiment that corresponds to the “operation rod” in the present invention.

The power unit3is an example embodiment that corresponds to the “driving unit” in the present invention.

The cutting unit4is an example embodiment that corresponds to the “cutting unit” in the present invention.

The handgrips209,309are example embodiments that correspond to the “handle” in the present invention.

The hammer bits219,319are example embodiments that correspond to the “tool bit” in the present invention.

DESCRIPTION OF NUMERALS