JP2013163234A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact tool which is effective in reducing weight.SOLUTION: An impact tool has: a motor 110 which is provided with a rotor 112, a stator 111, and an output shaft 113 which rotates together with the rotor 112; a crank mechanism 120 which converts the rotational motion of the motor 110 into rectilinear motion; and a tool drive mechanism 140 which is driven by the crank mechanism 120 and drives a tool bit 119 in a rectilinear manner. The crank mechanism 120 has: a crankshaft 125 which is formed as a body separate from the output shaft 113 of the motor 110; and motion conversion members 127 and 129 which convert the rotational motion of the crankshaft 125 into rectilinear motion and drive the tool drive mechanism 140. The motor 110 is configured as an outer rotor motor in which the rotor 112 is arranged at the outside of the stator 111. Moreover, the output shaft 113 and the crankshaft 125 are arranged coaxially with each other and connected to each other.

Description

  The present invention relates to an impact tool for performing a predetermined processing operation on a workpiece by driving a tool bit linearly using a crank mechanism.

  Japanese Patent Laying-Open No. 2008-279987 discloses a crank-type electric hammer that drives a tool bit linearly using a crank mechanism. The electric hammer as an impact tool described in the above publication has a configuration in which a tool bit is linearly driven by a crank mechanism driven by an electric motor. The electric motor employs an inner rotor type motor in which a rotor is arranged inside the stator. The motor speed is reduced by a reduction mechanism using a gear and transmitted to the crank mechanism, thereby causing a predetermined impact. The power is secured.

  The crank type electric hammer having the above-described configuration has a reduction mechanism between the output shaft of the electric motor and the crankshaft, so that the weight increases, and there is still room for improvement in this respect.

JP 2008-279588 A

  The present invention has been made in view of the above, and an object thereof is to provide a striking tool effective in reducing the weight.

  In order to solve the above problems, according to a preferred embodiment of the present invention, an impact tool for performing a predetermined processing operation on a workpiece by an impact operation in the major axis direction of a tool bit is configured. The impact tool includes a rotor, a stator, and a motor having an output shaft that rotates integrally with the rotor, a crank mechanism that converts the rotational motion of the motor into a linear motion, and a crank mechanism that is driven to linearize the tool bit. And a tool driving mechanism for driving. The crank mechanism includes a crankshaft formed separately from the output shaft of the motor, and a motion conversion member that converts the rotational motion of the crankshaft into a linear motion and drives the tool drive mechanism. The motor is configured as an outer rotor type motor in which a rotor is disposed outside a stator, and an output shaft and a crankshaft are disposed coaxially and connected to each other.

  According to the present invention, the motor is an outer rotor type motor in which the rotor is disposed outside the stator, so that the outer diameter of the rotating portion is large and a large rotor inertia moment can be provided. As compared with the same inner rotor type motor, it is possible to generate a large torque. For this reason, the motor output shaft and the crankshaft are arranged coaxially and connected to each other, thereby making it possible to omit the speed reduction mechanism required for the inner rotor type motor, reducing the weight of the machine, and improving operability. can do. Further, when the output of the motor is constant, a large torque can be generated to reduce the rotation speed, so that the vibration of the impact tool due to motor vibration can be reduced. Further, according to the present invention, since the motor output shaft and the crankshaft are formed separately, it is possible to separate the motor side and the crank mechanism at the time of failure, thereby improving the repair exchangeability.

According to the further form of the impact tool which concerns on this invention, the output shaft and the crankshaft are each supported by the bearing in the axial direction several places.
According to this embodiment, the output shaft and the crankshaft can be stably rotated while supporting a high output by supporting a plurality of locations.

According to the further form of the impact tool which concerns on this invention, the several bearing which supports an output shaft is supported by the single bearing support member.
According to this aspect, by adopting a configuration in which a plurality of bearings are supported by a single bearing support member, the centering accuracy of the output shaft can be improved compared to a configuration in which the bearings are supported by separate bearing support members, The number of members can be reduced, the structure can be simplified, and the assemblability can be improved.

According to the further form of the impact tool according to the present invention, the output shaft and the crankshaft are connected via the interposition member, whereby torque is transmitted from the output shaft in the order of the interposition member and the crankshaft.
According to this embodiment, the interposed member can function as a torque transmission member.

According to the further form of the impact tool which concerns on this invention, one axis | shaft of an output shaft and a crankshaft is inserted inside the other axis | shaft, and the interposed member is the outer side of one axis | shaft, and the other axis | shaft. It is arranged between the inside.
According to this aspect, the interposition member can function not only as a torque transmission member but also as a misalignment absorbing member that allows misalignment between the output shaft and the crankshaft.

According to the further form of the impact tool which concerns on this invention, it has a biasing member which biases an interposition member to an axial direction. A first recess along the axial direction is formed on the outer side of one shaft, a second recess along the axial direction is formed on the inner side of the other shaft, and the interposition member includes the first recess and the first recess. The torque can be transmitted by engaging the two recesses. Note that the “biasing member” in this embodiment typically corresponds to a compression coil spring.
According to this aspect, when one shaft is inserted inside the other shaft so as to assemble the output shaft and the crankshaft, the interposition member is engaged with any one of the first recess and the second recess. Even if they do not match, if the output shaft and the crankshaft are relatively rotated in the inserted state, the interposing member is engaged with one of the concave portions by the urging force of the urging member. For this reason, both shafts can be easily assembled.

  According to the present invention, an impact tool effective in reducing the weight is provided.

It is a sectional view showing the whole electric hammer composition concerning a 1st embodiment. It is sectional drawing which expands and shows the connection structure of a motor shaft and a crankshaft. It is the sectional view on the AA line of FIG. It is sectional drawing which shows the whole structure of the hammer drill which concerns on 2nd Embodiment. It is sectional drawing which expands and shows the structure of the drive mechanism part of a hammer drill. It is the BB sectional view taken on the line of FIG.

(First embodiment of the present invention)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. In the present embodiment, description will be made using an electric hammer as an example of an impact tool. As shown in FIG. 1, the electric hammer 100 is mainly configured by a main body portion 101 as a tool main body that forms an outline of the electric hammer 100. A hammer bit 119 is detachably attached to the distal end region of the main body 101 via a cylindrical tool holder 159. The hammer bit 119 is mounted so as to be relatively movable in the major axis direction with respect to the tool holder 159 and to rotate integrally in the circumferential direction. A hand grip 107 gripped by the operator is connected to the end of the main body 101 opposite to the tip region. The handgrip 107 extends in the vertical direction in FIG. 1 intersecting the major axis direction of the hammer bit 119, and is substantially D-shaped in a side view in which each end in the extending direction is connected to the main body 101. It is provided as a main handle.

  The hammer bit 119 corresponds to a “tool bit” in the present invention. In the present embodiment, for convenience, the hammer bit 119 side in the longitudinal direction of the main body 101 is defined as “front side” or “front side”, and the handgrip 107 side is defined as “rear side” or “rear side”. ”. 1 is defined as “upper side” or “upper side”, and the lower side of the page is defined as “lower side” or “lower side”.

  The main body 101 is mainly composed of an outer housing 103 that houses the electric motor 110, the motion conversion mechanism 120, and the striking element 140. The electric motor 110 corresponds to the “motor” in the present invention. The rotation output of the electric motor 110 is appropriately converted into a linear motion by the motion conversion mechanism 120 and then transmitted to the striking element 140, and the major axis direction of the hammer bit 119 (the left-right direction in FIG. 1) via the striking element 140. Generates an impact force on. The electric motor 110 is energized and driven by a pulling operation of a trigger 107 a disposed on the hand grip 107.

  As shown in FIG. 2, the electric motor 110 is configured as an outer rotor type motor in which a stator 111 is disposed on the inner side and a rotor 112 that rotates integrally with the motor shaft 113 is disposed on the outer side. 113) is arranged so as to intersect perpendicularly the major axis direction of the hammer bit 119 (hence, the major axis direction of the main body 101). The stator 111 is mainly composed of a coil holding member 111b for holding a drive coil 111a for driving the rotor 112 and a cylindrical mounting member 111c for supporting the coil holding member 111b. . The cylindrical mounting member 111 c is fixedly supported by an inner housing 104 that is disposed and fixed in the outer housing 103. The inner housing 104 is provided as a divided housing including an upper housing portion 104a and a lower housing portion 104b that are divided into two in the vertical direction. The lower housing part 104b is formed in a substantially cylindrical shape extending in the vertical direction, and the cylindrical mounting member 111c of the stator 111 is fitted and fixed to the outer side of the cylindrical part of the lower housing part 104b. .

  The rotor 112 is formed as a substantially cup-shaped member supported so as to be integrally rotatable with the motor shaft 113, and a magnet 115 is attached to the inner peripheral surface (side wall inner surface) facing the outer periphery of the stator 111, One end (lower end) in the axial direction of the motor shaft 113 is press-fitted into the center of the cup-shaped bottom and integrated. The motor shaft 113 corresponds to the “output shaft” in the present invention. The motor shaft 113 to which the rotor 112 is fixed extends through the inner space of the lower housing portion 104b of the inner housing 104 in a loosely fitting manner, and extends upward in the inner space with a bearing (ball bearing). ) 116, and the lower side is supported by a bearing (needle bearing) 117 to be rotatable. That is, the motor shaft 113 is supported by the bearings 116 and 117 at a plurality of locations in the axial direction. The bearings 116 and 117 correspond to “a plurality of bearings” in the present invention, and the lower housing portion 104 b that supports the bearings 116 and 117 corresponds to “a single bearing support member” in the present invention.

  As shown in FIG. 2, the motion conversion mechanism 120 connects the crankshaft 125, the eccentric shaft 127 provided at a position shifted from the rotation center of the crankshaft 125, the piston 131, and the piston 131 and the eccentric shaft 127. It is comprised by the crank mechanism which consists of a connecting rod 129 grade | etc.,. The crankshaft 125 is formed separately from the motor shaft 113 of the electric motor 110, and is disposed coaxially with the motor shaft 113 so as to rotate integrally therewith. The crankshaft 125 is disposed above the motor shaft 113 and is rotatably supported by bearings (ball bearings) 126 at two upper and lower positions in the axial direction. The bearing 126 of the crankshaft 125 is supported by the upper housing 104a of the inner housing 104. The rotational motion of the crankshaft 125 is converted into a linear motion via the eccentric shaft 127 and the connecting rod 129 and transmitted to the piston 131. The piston 131 is provided as a driver for driving the striking element 140 and is slid linearly in the cylinder 141 in the same direction as the long axis direction of the hammer bit 119. The eccentric shaft 127 and the connecting rod 129 correspond to the “motion converting member” in the present invention.

  Next, a connection structure between the crankshaft 125 and the motor shaft 113 will be described. As shown in FIG. 2, the crankshaft 125 has a through-hole 125a having a circular cross section passing through the center, and the upper end of the motor shaft 113 is inserted into the through-hole 125a from below (inserted). ) Two concave grooves 125b are formed in the inner surface of the through hole 125a so as to extend in the axial direction with a predetermined length downward from the upper end surface of the crankshaft 125. As shown in FIG. 3, the concave groove 125b is a groove having a substantially semicircular cross section provided at a symmetrical position across the central axis of the crankshaft 125, and each concave groove 125b has a substantially cylindrical engagement. The combined member 133 is fitted so that approximately half of the radial direction protrudes toward the through hole 125a. The engaging member 133 fitted in the concave groove 125b is allowed to move in the axial direction of the crankshaft 125, but is restricted in relative movement in the circumferential direction. The concave groove 125b is set to have an arc that is at least larger than a semicircle in order to prevent the engaging member 133 from falling off the concave groove 125b toward the through hole 125a. The concave groove 125b corresponds to the “first concave portion” in the present invention.

  Further, the engaging member 133 is always urged downward by a compression coil spring 135 disposed on the upper side of the through hole 125a. Therefore, in a state before assembly in which the motor shaft 113 is fitted into the crankshaft 125, the crankshaft 125 is in contact with the lower end of the concave groove 125b. The upper end of the compression coil spring 135 is supported by the crankshaft 125 via a retaining ring 137. The compression coil spring 135 corresponds to the “biasing member” in the present invention.

  On the other hand, on the outer surface of the upper shaft portion of the motor shaft 113, as shown in FIGS. 2 and 3, two engaging recesses that are point-symmetric with respect to the central axis of the motor shaft 113 corresponding to the recess groove 125 b of the crankshaft 125. 113a is formed. The engaging recess 113a is substantially semicircular in cross section, and the engaging member 133 is inserted and engaged from above in the axial direction, and relative movement in the circumferential direction with respect to the motor shaft 113 is restricted. As a result, the motor shaft 113 and the crankshaft 125 are connected via the engaging member 133, and torque is transmitted in the order of the motor shaft 113, the engaging member 133, and the crankshaft 125. The engagement member 133 corresponds to the “interposition member” in the present invention, and the engagement recess 113a corresponds to the “second recess” in the present invention.

  As shown in FIG. 1, the upper housing portion 104 a of the inner housing 104 extends in the front-rear direction for accommodating the cylinder 141 and the tool holder 159 and in the vertical direction for accommodating the crankshaft 125. A substantially cylindrical rear portion. Then, as shown in FIG. 2, the lower housing part 104b is arranged oppositely on the lower side of the rear part of the upper housing part 104a, and is fastened and joined by fastening means such as screws (not shown). The The electric motor 110 is preferably prepared as a motor assembly in which constituent members such as a stator 111, a rotor 112, and a motor shaft 113 are previously assembled to the lower housing portion 104b. The prepared motor assembly is assembled by inserting the upper end portion of the motor shaft 113 into the through hole 125a of the crankshaft 125 and joining the lower housing portion 104b to the rear portion of the upper housing portion 104a as described above. It is done.

  When the upper shaft portion of the motor shaft 113 is fitted into the through hole 125a of the crankshaft 125 from below during the above assembly, the positions of the concave groove 125b and the engaging concave portion 113a are shifted in the circumferential direction. The engaging member 133 is pushed by the upper end surface of the motor shaft 113 and moves upward in the concave groove 125b against the elastic force of the compression coil spring 135, and is held in the elastic state at the moved position. . Accordingly, when the motor shaft 113 is relatively rotated in the circumferential direction with respect to the crankshaft 125 in such a state, the engaging member 133 biased downward by the elastic force of the compression coil spring 135 is engaged with the concave groove 125b. At the same time that the circumferential position of the recess 113a coincides, it is inserted into the engagement recess 113a and engaged. For this reason, the motor shaft 113 can be easily assembled to the crankshaft 125.

  As shown in FIG. 1, the striking element 140 is slidably disposed in a striker 143 as a striking element slidably disposed on the bore inner wall of the cylinder 141 and in a front cylinder portion in the tool holder 159. At the same time, an impact bolt 145 serving as an intermediate for transmitting the operating energy (striking force) of the striker 143 to the hammer bit 119 is mainly used. The striker 143 is driven via an air spring in the air chamber 141a of the cylinder 141 in accordance with the sliding motion of the piston 131, and collides with (impacts) an impact bolt 145 disposed in the tool holder 159. The hammering force 119 is transmitted to the hammer bit 119. The striking element 140 corresponds to the “tool driving mechanism” in the present invention.

  When the electric motor 110 is energized and driven by the pull operation of the trigger 107a, the electric hammer 100 configured as described above is extended from the motion conversion mechanism 120 configured by a crank mechanism to the hammer bit 119 via the striking element 140. An axial striking force is applied. As a result, the hammer bit 119 performs a hammering operation in the long axis direction, and performs a drilling operation on the workpiece (concrete).

  Now, according to the present embodiment, the rotor 112 of the electric motor 110 is constituted by an outer rotor type motor arranged outside the stator 111. By adopting the outer rotor type motor, the outer diameter of the rotor 112 can be increased and a large rotor inertia moment can be provided. For this reason, compared with an inner rotor type motor, a big torque can be generated. If the electric motor is an inner rotor type motor, a speed reduction mechanism must be provided between the motor shaft and the intermediate shaft in order to secure the torque necessary to generate a predetermined striking force, which increases the weight. Or, there is a possibility that the aircraft will be enlarged. However, according to the present embodiment, since the electric motor 110 is composed of the outer rotor type motor, the speed reduction mechanism is not required, and thus the weight of the machine body can be reduced and the size can be reduced. The operability of the electric hammer 100 can be improved. In addition, when the output of the electric motor 110 is constant, the number of rotations can be lowered, so that vibration of the electric hammer 100 due to motor vibration can be reduced, and no countermeasure for resonance is required, and durability of the bearings 116 and 117 is improved. Can do.

  Further, according to the present embodiment, in the connection structure between the motor shaft 113 and the crankshaft 125, the engaging member 133 is inserted into the through hole 125a of the crankshaft 125 by the compression coil spring 135 toward the motor shaft 113 side. It is set as the structure which urged | biased in the direction of the bullet. For this reason, if the motor shaft 113 is inserted into the through hole 125a in order to assemble the motor shaft 113 to the crankshaft 125, the engaging member 133 does not engage with the engaging recess 113a of the motor shaft 113 at the time of the insertion. In addition, the engagement member 133 can be automatically engaged with the engagement recess 113a by the elastic force of the compression coil spring 135 when the motor shaft 113 and the crank shaft 125 rotate relative to each other after the insertion. For this reason, the motor shaft 113 and the crankshaft 125 can be easily assembled. In addition, since the motor shaft 113 and the crankshaft 125 are formed separately, the electric motor 110 side and the crank mechanism side can be separated in the event of a failure, so that the repair exchangeability can be improved.

  Further, according to the present embodiment, the motor shaft 113 and the crankshaft 125 are connected by engaging the engaging member 133 fixed in the circumferential direction of the crankshaft 125 with the engaging recess 113a of the motor shaft 113. It is the structure to do. For this reason, even if there is a slight misalignment between the motor shaft 113 and the crankshaft 125 by setting a predetermined gap in the radial direction or circumferential direction between the engagement member 133 and the engagement recess 113a, The misalignment can be allowed. That is, the engaging member 133 functions not only as a torque transmission member but also as a misalignment absorbing member that allows misalignment between the motor shaft 113 and the crankshaft 125.

  Further, according to the present embodiment, the motor shaft 113 is supported by the bearings 116 and 117 at a plurality of axial positions, and the crankshaft 125 is configured by the bearing 126 at a plurality of axial positions. Therefore, the motor shaft 113 and the crankshaft 125 can be stably rotated while supporting high output. The upper and lower bearings 116 and 117 for supporting the motor shaft 113 are supported by a single member, that is, the lower housing portion 104 b of the inner housing 104. For this reason, compared with the case where the upper and lower bearings 116 and 117 are supported by separate bearing support members, the number of members can be reduced, the structure can be simplified, and the assemblability can be improved.

(Second embodiment of the present invention)
Next, a second embodiment of the present invention will be described with reference to FIGS. This embodiment is an example in which the hammer is changed from an electric hammer to a hammer drill. FIG. 4 shows the overall configuration of the hammer drill 200. The hammer drill 200 is configured such that a rotation operation around the long axis direction is added to the hammer bit 119 in addition to a striking operation in the long axis direction. That is, it differs from the electric hammer 100 in that it further includes a power transmission mechanism 150 for transmitting the rotation output of the electric motor 110 to the hammer bit 119 separately from the motion conversion mechanism 120 and the striking element 140. The configuration is the same as that of the electric hammer 100 described in the first embodiment. Therefore, in this embodiment, the power transmission mechanism 150 that is different from the first embodiment will be mainly described, and the other components are denoted by the same reference numerals as those used in the first embodiment. Description is omitted or simplified.

  As shown in FIG. 5, the power transmission mechanism 150 according to this embodiment includes a first intermediate shaft 151 and a second intermediate shaft 152 that are arranged in parallel to the motor shaft 113 (accordingly, the crankshaft 125). A first intermediate gear 154 and a second intermediate gear 155 having a smaller diameter than the first intermediate gear 154 are fixedly attached to the first intermediate shaft 151, and the second intermediate gear 155 is always attached to the second intermediate shaft 152. A third intermediate gear 156 that meshes and engages is fixedly attached. The first intermediate gear 154 always meshes and engages with a drive gear 153 driven by the electric motor 110. Accordingly, the torque of the electric motor 110 is reduced from the drive gear 153 through the first to third intermediate gears 154, 155 and 156 at a predetermined reduction ratio and transmitted to the second intermediate shaft 152.

  The torque transmitted to the second intermediate shaft 152 is transmitted from the small bevel gear 157 integrally formed with the second intermediate shaft 152 to the large bevel gear 157 engaged with the small bevel gear 157, and the large bevel gear. It is configured to be transmitted to the hammer bit 119 via a tool holder 159 as a final output shaft coupled to 158.

  In this embodiment, in the inner housing 104, the lower housing portion 104b that supports the electric motor 110 includes a first intermediate shaft 151 in addition to a motor support region that supports the electric motor 110, as shown in FIG. And an intermediate shaft support region that rotatably supports the second intermediate shaft 152 via bearings 151a and 152a, and is joined to the lower side of the upper housing portion 104a.

  In the hammer drill 200 configured as described above, the electric motor 110 is configured as an outer rotor type motor in which the rotor 112 is disposed outside the stator 111, and the motor shaft 113 is coaxial with the crankshaft 125 of the motion conversion mechanism 120. It arrange | positions and is connected through the engaging member 133 (refer FIG.5 and FIG.6). The details of the connection structure are the same as those in the first embodiment described above. In this embodiment, the drive shaft 153 is provided on the motor shaft 113 so that the torque of the motor shaft 113 is transmitted to the hammer bit 119.

  Therefore, according to this embodiment, in the hammer drill 200, it is possible to reduce the weight and size of the machine body, thereby improving the operability of the electric hammer 100 when performing a machining operation, and the like. Similar effects can be obtained.

  In this embodiment, the drive gear 153 is described as being attached to the motor shaft 113, but the configuration may be changed to a configuration provided on the crankshaft 125.

  In the first and second embodiments, the engaging member 133 is a cylindrical member, but may be replaced with a steel ball. In the first and second embodiments, an engaging member is disposed as an interposed member between the outer side of the motor shaft 113 and the inner side of the crankshaft 125, and both shafts 113 and 125 are connected. For example, you may change to the structure which connects both the shafts 113 and 125 using a coupling.

  Further, regarding the connection structure between the motor shaft 113 and the crankshaft 125, the motor shaft 113 and the crankshaft 125 are connected via an engaging member 133 that is elastically biased in the axial direction by the compression coil spring 135. Although it was set as the structure, you may change into the structure which changes to this structure and connects a key as an interposed member. Alternatively, without using an intervening member, a spline hole may be set on one shaft, a spline shaft may be set on the other shaft, and the connection may be changed by spline fitting. It is also possible to change to a connected structure used.

100 Electric hammer (blow tool)
DESCRIPTION OF SYMBOLS 101 Main body part 103 Outer housing 104 Inner housing 104a Upper housing part 104b Lower housing part (Single bearing support member)
107 hand grip 107a trigger 110 electric motor (motor)
111 Stator 111a Drive coil 111b Coil holding member 111c Cylindrical mounting member 112 Rotor 113 Motor shaft (output shaft)
113a Engaging recess (second recess)
115 Magnet 116 Bearing (multiple bearings)
117 Bearing (multiple bearings)
119 Hammer Bit (Tool Bit)
120 Motion conversion mechanism (crank mechanism)
125 Crankshaft 125a Through hole (hole)
125b Groove (first recess)
126 Bearing 127 Eccentric shaft (motion conversion member)
129 Connecting rod (motion conversion member)
131 piston 133 engaging member (intervening member)
135 Compression coil spring (biasing member)
137 Retaining Ring 140 Impact Element (Tool Drive Mechanism)
141 cylinder 141a air chamber 143 striker 145 impact bolt 150 power transmission mechanism 151 first intermediate shaft 151a bearing 152 second intermediate shaft 152a bearing 153 drive gear 154 first intermediate gear 155 second intermediate gear 156 third intermediate gear 157 small bevel gear 158 Large bevel gear 159 Tool holder

Claims (6)

A striking tool that performs a predetermined processing operation on a workpiece by a striking motion in the long axis direction of a tool bit,
A motor having an output shaft that rotates integrally with the rotor, the stator, and the rotor;
A crank mechanism for converting the rotational motion of the motor into linear motion;
A tool drive mechanism that is driven by the crank mechanism and drives the tool bit linearly;
The crank mechanism has a crankshaft formed separately from the output shaft of the motor, and a motion conversion member that converts the rotational motion of the crankshaft into a linear motion to drive the tool drive mechanism,
The motor is configured as an outer rotor type motor in which the rotor is disposed outside the stator,
The impact tool, wherein the output shaft and the crankshaft are coaxially arranged and connected to each other. The impact tool according to claim 1,
Each of the output shaft and the crankshaft is supported by a bearing at a plurality of locations in the axial direction. The impact tool according to claim 2,
A plurality of bearings that support the output shaft are supported by a single bearing support member. The impact tool according to any one of claims 1 to 3,
The impact tool according to claim 1, wherein the output shaft and the crankshaft are connected via an interposed member, whereby torque is transmitted from the output shaft in the order of the interposed member and the crankshaft. The impact tool according to claim 4,
One of the output shaft and the crankshaft is inserted inside the other shaft, and the interposition member is disposed between the outside of the one shaft and the inside of the other shaft. A striking tool characterized by The impact tool according to claim 5,
A biasing member for biasing the interposition member in the axial direction;
A first recess along the axial direction is formed outside the one shaft,
A second recess along the axial direction is formed inside the other shaft,
The impact tool is characterized in that the torque can be transmitted by engaging the interposition member with the first recess and the second recess.

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