POWER TOOL WITH HAMMER MECHANISM

Abstract

A power tool includes a motor, a hammer mechanism, and a housing. The motor includes a motor shaft that rotates about a motor axis. The hammer mechanism includes a cylinder and a hammer element adjacent to an air chamber defined within the cylinder, and is configured to convert rotational motion of the motor shaft into linear motion of the hammer element along a predetermined hammer axis by utilizing action of an air spring of the air chamber. The housing houses the motor and hammer mechanism. The motor axis is arranged parallel to the hammer axis and passes through the inside of the cylinder.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power tool having a hammer mechanism. BACKGROUND

[0002] For example, US 5 002 134 A discloses a power tool with a hammer mechanism. The power tool includes a support shaft rotated by the driving force of a motor, a rotary body rotated by rotation of the support shaft, a striking member mounted on the rotary body, and a blade as a tool accessory. In this power tool, a rotary motion of the motor is converted into a linear motion of the blade using a cam mechanism rotated by the driving force of the motor. SHORT SUMMARY

[0003] However, with such a state-of-the-art technology, the motor's driving force is mechanically converted into a reciprocating motion of the tool accessory. Therefore, vibration of the power tool may be increased, and sufficient hammer force of the tool accessory cannot be achieved.

[0004] One non-limiting aspect of the present disclosure provides a power tool comprising a motor, a hammer mechanism, and a housing. The motor has a motor shaft that rotates about a motor axis. The hammer mechanism includes a hammer element adjacent to an air chamber defined within the cylinder and is configured to convert rotational movement of the motor shaft into linear movement of the hammer element along a predetermined hammer axis by utilizing the action of an air spring of the air chamber. The housing houses the motor and the hammer mechanism. The motor axis is arranged parallel to the hammer axis and passes through the interior of the cylinder.

[0005] In the power tool according to the above-described aspect, by providing the hammer mechanism utilizing an air spring, vibration of the power tool can be reduced, and large kinetic energy is transmitted to the tool attachment compared to a hammer mechanism that mechanically transmits kinetic energy. Furthermore, the motor axis is arranged close to the hammer axis, and components from the motor to the tool attachment are arranged substantially in a straight line, so that a user can easily apply a linear force to the tool attachment. Therefore, the power tool suitable for earthwork (excavation work) is provided. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an external shape of a power tool with a hammer mechanism according to a first embodiment of the disclosure. Fig. 2 shows the configuration of a battery mounting part. Fig. 3 is a cross-sectional view taken along a line III-III in Fig. 2. Fig. 4 shows the configuration of a hammer mechanism. Fig. 5 is a cross-sectional view showing a part along a line VV in Fig. 1 shows. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0006] Representative and non-limiting embodiments according to the present disclosure are described in detail below with reference to the drawings. This detailed description is merely intended to show those skilled in the art details for practicing advantageous examples of the present disclosure and is not intended to limit the scope of the present disclosure. Furthermore, additional features and inventions disclosed below may be used separately or in conjunction with other features or inventions to provide further improved tools, and methods of making and using them.

[0007] Furthermore, combinations of features and methods disclosed in the following detailed description are not necessarily required in the practice of the present disclosure and are specifically provided to describe representative specific examples of the present disclosure. Moreover, in illustrating additional and effective embodiments of the present disclosure, various features of the representative specific examples described above and below, as well as various features described in independent and dependent claims, need not necessarily be combined as in the specific examples provided herein or in any particular order.

[0008] All features recited in the present disclosure and / or within the scope of the claims are intended to be considered separate and independent of each other for the purpose of the original disclosure and also for the purpose of limiting the claimed invention, regardless of the combination of features in the embodiments and / or the claims. Furthermore, descriptions referring to all numerical ranges and groups or collections are treated as intended to disclose configurations related thereto, as limitations on the disclosure at the time of filing and the specific subject matter claimed.

[0009] In addition or alternatively to the preceding embodiments, the power tool may further comprise a main handle. The main handle includes (i) a grip portion configured to be held by a user, (ii) a first connecting portion connecting a first end of the grip portion to the housing, and (iii) a second connecting portion connecting a second end of the grip portion to the housing. The hammer axis may pass between the first end and the second end of the grip portion when the power tool is viewed in a direction perpendicular to the hammer axis.

[0010] With the power tool according to this embodiment, a user can easily push the power tool forward along the hammer axis by operating the main handle, so that the power tool suitable for earthwork (excavation work) is provided.

[0011] In addition or alternatively to the foregoing embodiments, the hammer mechanism may comprise (i) a second bevel gear meshing with a first bevel gear provided on the motor shaft, and (ii) a crankshaft formed integrally with the second bevel gear and rotating together with the second bevel gear.

[0012] In the power tool according to this embodiment, the driving force of the motor is transmitted efficiently.

[0013] Additionally or alternatively to the preceding embodiments, an extension direction of the handle part may be (i) parallel to a plane perpendicular to a rotational axis of the second bevel gear and (ii) cross the hammer axis.

[0014] According to this embodiment, the power tool is provided to have a good balance when the main handle is held by a user.

[0015] In addition or alternatively to the preceding embodiments, the power tool may include a controller. The controller may control the motor. The main handle may be connected to a rear end portion of the housing. The controller may be (i) housed in the housing and (ii) arranged between the motor and the handle portion in a direction of extension of the hammer axis.

[0016] In the power tool according to this embodiment, the controller is efficiently arranged within the housing.

[0017] In addition or alternatively to the preceding embodiments, the housing may further comprise a battery mounting portion to which a battery (battery pack) for supplying power to the motor is removably attachable. The hammer axis is arranged to pass through at least a portion of the battery mounting portion.

[0018] In the power tool according to this embodiment, with the arrangement of the battery on the hammer axis, the increase in size of the housing in a direction crossing the hammer axis is reduced or prevented.

[0019] Additionally or alternatively to the preceding embodiments, the battery mounting part can be arranged between the first connecting part and the second connecting part on the housing in an extension of the handle part.

[0020] In the power tool according to this embodiment, the battery is surrounded by the main handle so that the battery is protected by using the main handle.

[0021] In addition or alternatively to the preceding embodiments, the housing may include an inner housing. The inner housing may include the motor and the hammer mechanism. An outer housing may house the inner housing. The main handle may be connected to the outer housing. An elastic member may be disposed in contact with the inner housing and the outer housing between the inner housing and the outer housing.

[0022] In the power tool according to this embodiment, the transmission of vibration from the inner casing accommodating a vibration source(s) to the outer casing while the power tool is driven can be reduced or prevented.

[0023] Additionally or alternatively to the preceding embodiments, the power tool with a hammer mechanism may further include a front handle. The front handle may be configured to be held by a user. An extension direction of the hammer axis may define a front-to-back direction of the power tool. The main handle may be connected to the housing rearward of the rotational axis of the second bevel gear. The front handle may be connected to the housing frontward of the rotational axis of the second bevel gear.

[0024] With the power tool according to this embodiment, a user can easily transmit force for pressing the tool attachment against a working object to the power tool using the main handle and the front handle. Thus, the power tool suitable for excavation work is provided.

[0025] In addition or alternatively to the preceding embodiments, the power tool with a hammer mechanism may further comprise a light-emitting part. The light-emitting part may be configured to emit light toward a work area.

[0026] With the power tool according to this embodiment, the visibility of the working area of the power tool is improved by providing the light emitting part. A. First embodiment:

[0027] A power tool 100 with a hammer mechanism (hereinafter simply referred to as the power tool 100) according to the first embodiment of the present disclosure will now be described with reference to the drawings. In this embodiment, an electric shovel is described as a representative example of the power tool 100. The electric shovel is a handheld power tool configured for digging, shoveling, scooping, or crushing earth, sand, gravel, coal, snow, or the like, or for other similar work. The electric shovel is configured to linearly reciprocate a bucket as a tool accessory TT mounted to a front end of a housing 60 along a hammer axis TX (a movement which will hereinafter simply be referred to as a hammer movement) by utilizing the driving force of the motor. The bucket is intended, for example,For use in civil engineering, agriculture, or home use. The bucket is also referred to as a shovel. The 100 power tool can also be used for work other than earthworks by replacing the TT tool accessory.

[0028] In this specification, for the sake of simplicity, the extending direction of the hammer axis TX is defined as a front-to-back direction of the power tool 100. In the front-to-back direction, one side of a front end part 61 of the housing 60, on which a tool holder 90 (see Fig. 3) is defined as the front side of the power tool 100, and the opposite side is defined as the rear side of the power tool 100. A direction parallel to a rotation axis CX (see Fig. 3) A crankshaft 564 (described later) is defined as an up-down direction of the power tool 100. In the up-down direction, the direction from the crankshaft 564 toward the hammer axis TX is defined as an upward direction, and the opposite direction is defined as a downward direction. A direction perpendicular to the front-back direction and the up-down direction is defined as a left-right direction.

[0029] The power tool 100 comprises a housing 60, a motor 20 (see Fig. 3) and a hammer mechanism 50 (see Fig. 3) which are accommodated in the housing 60. As shown in Fig. 1, the housing 60 is an elongated hollow housing having a substantially circular cylindrical shape and extending along the hammer axis TX. The housing 60 includes the front end portion 61 on the front side of the housing 60, a hammer mechanism housing portion 62, a motor housing portion 63, and a rear end portion 64 on the opposite side to the front end portion 61.

[0030] A main handle 70 is connected to the rear end portion 64 of the housing 60, and a front handle 80 is connected to the hammer mechanism housing portion 62. The main handle 70 is generally U-shaped and includes a grip portion 76 configured to be held by a user, a first extension portion 71, a second extension portion 72, a first connecting portion 70L, and a second connecting portion 70R. The main handle 70 is fixed to the housing 60 at both ends via the first connecting portion 70L and the second connecting portion 70R. Thus, the main handle 70 and the housing 60 together form an annular (loop-shaped) configuration when viewed from above.

[0031] The grip portion 76 is a part of the main handle 70 that is configured to be held by a user. The grip portion 76 has a generally circular-cylindrical shape. The extension direction of the grip portion 76 can be defined, for example, by a direction of a central axis HX of the grip portion 76. As shown in Fig. 3 and Fig. 5, the extending direction of the handle portion 76 is, for example, parallel to a plane OS perpendicular to the rotational axis CX of a second bevel gear 562 and perpendicular to the hammer axis TX. In this embodiment, the extending direction of the handle portion 76 coincides with the left-right direction. With such a configuration, the gripping position of the main handle 70 and the positions of the center of gravity of the second bevel gear 562 and the crankshaft 564 are arranged such that the power tool 100 has good weight balance in the left-right direction. In another embodiment, the extending direction of the handle portion 76 may be a direction that crosses the hammer axis TX at a predetermined angle, provided that it is, for example, parallel to the plane OS.An intersection point of the central axis HX of the handle part 76 and a left outer peripheral surface of the handle part 76 is referred to as a first end 76L of the handle part 76, and an intersection point of the central axis HX and a right outer peripheral surface of the handle part 76 is referred to as a second end 76R of the handle part 76. The first extension part 71 is a part of the main handle 70 that connects the first connecting part 70L and the first end 76L of the handle part 76. The second extension part 72 is a part of the main handle 70 that connects the second connecting part 70R and the second end 76R of the handle part 76.

[0032] As in Fig. 3, the grip portion 76 of the main handle 70 is arranged rearward of the rotational axis CX of the second bevel gear 562 and rearward of the housing 60. Furthermore, the hammer axis TX passes through between the first end 76L and the second end 76R of the grip portion 76 when the power tool 100 is rotated in a direction perpendicular to the hammer axis TX (specifically, from above in the up-down direction as shown in Fig. 5). In this embodiment, the hammer axis TX passes through the handle part 76. In the example shown in Fig. 3, the hammer axis TX crosses the central axis HX of the handle portion 76. With the extension direction of the main handle 70 arranged along the hammer axis TX, a user can easily push the tool accessory TT along the hammer axis TX by pushing the rear end of the main handle 70. Furthermore, with the extension direction of the handle portion 76 arranged on the hammer axis TX, a user can easily push the tool accessory TT along the hammer axis TX by pushing the rear end of the main handle 70. Therefore, the power tool 100 is suitable for earthwork (excavation work). The hammer axis TX does not have to be perpendicular to the extension direction of the handle portion 76, but may, for example, cross the extension direction of the handle portion 76 at a predetermined angle in a range between the first end 76L and the second end 76R of the handle portion 76.The handle portion 76 may be offset upwardly or downwardly relative to the hammer axis TX, or may be offset upwardly and downwardly relative to the plane OS.

[0033] The plane OS perpendicular to the rotational axis CX of the second bevel gear 562 passes through the handle portion 76 and the first and second connecting portions 70L, 70R. In other words, the main handle 70 is configured to extend rearwardly along the plane OS from the housing 60. In the example shown in Fig. 1, the first extension portion 71 extends rearward from the first connecting portion 70L, and the second extension portion 72 extends rearward from the second connecting portion 70R. With such a configuration of the power tool 100, a user can easily apply a force along the plane OS using the main handle 70, making the power tool 100 suitable for excavation work. In this embodiment, the plane OS includes the central axis HX of the handle portion 76.

[0034] As in Fig. 1, the front handle 80 is generally U-shaped and includes a grip portion 86 configured to be held by a user and connecting portions 80L, 80R. The grip portion 86 has a generally circular cylindrical shape extending in the left-right direction and is disposed above the housing 60. The front handle 80 is connected at both ends to the housing 60 via the connecting portions 80L, 80R. In this embodiment, the connecting portions 80L, 80R support the front handle 80 in such a manner as to enable adjustment of the position of the front handle 80 about a support axis FX relative to the housing 60. However, the front handle 80 is not limited to being of the position adjustment type, but may be immovably fixed to the housing 60. For example, the front handle 80 may be reversed relative to the assembled state in Fig. 1. In this case, the front handle portion 86 is located below the housing 60. Furthermore, the front handle 80 may, for example, be configured such that it is removable from the housing 60. In this case, the front handle 80 may be configured such that it can be freely changed in position, either to the position above the housing 60 or to the position below the housing 60, if desired.

[0035] The connecting parts 80L, 80R are connected to the housing 60 at a position slightly forward of the center of the housing 60 in the front-back direction. Specifically, as shown in Fig. 4, the front handle 80 is connected to the housing 60 at a position forward of the rotation axis CX of the second bevel gear 562. With this arrangement, a user can easily transmit a force to the power tool 100 for pressing the tool attachment TT against a work object using the front handle 80, so that the power tool 100 is suitable for excavation work.

[0036] In this embodiment, the support axis FX of the front handle 80 is perpendicular to the hammer axis TX. When the housing 60 is pushed forward using the front handle 80, a user can transmit the force to the housing 60 via the support axis FX by operating the front handle 80. With such a configuration of the power tool 100 of this embodiment, a user can easily push the housing 60 forward along the hammer axis TX, making the power tool 100 suitable for excavation work.

[0037] As in Fig. 1, a switch trigger 77 is provided on the grip portion 76 of the main handle 70. The switch trigger 77 is a so-called momentary switch. For example, when a user presses the switch trigger 77 while holding the grip portion 76, the power tool 100 is turned on and the motor 20 is driven.

[0038] The trigger switch 77 is disposed at a position opposite the rear end portion 64 of the housing 60 on the grip portion 76. For example, when using the power tool 100, a user holds the grip portion 76 of the main handle 70 with one hand while holding the grip portion 86 of the front handle 80 with the other hand. The user can perform shoveling of a working object, such as soil, by pushing the power tool 100 forward using the main handle 70 while pressing the tool attachment TT against the working object. The user can start and stop a hammer motion at any time during excavation work by turning the trigger switch 77 on and off while operating (gripping) the main handle 70. Furthermore, the user can appropriately perform the shoveling operation (work) with the power tool 100 by using the front handle 80.This makes the power tool 100 suitable for earthworks.

[0039] A light-emitting part LT is provided on the housing 60. The light-emitting part LT is, for example, an LED light that uses a battery BAT as a power source. The light-emitting part LT is configured to emit (illuminate) light toward the tool accessory TT or a work area including a work object or its surroundings. The visibility of the work area of the power tool 100 is improved by providing the light-emitting part LT. In this embodiment, the light-emitting part LT is located in a position surrounded by the front handle 80, so that the light-emitting part LT is protected from impact by utilizing the front handle 80.

[0040] The battery BAT for supplying power to the motor 20 is arranged at the rear end portion 64 of the housing 60. In this disclosure, a rechargeable battery (battery pack) having a known structure is used as the battery BAT.

[0041] Fig. 2 shows the power tool 100 in a state where the battery BAT is removed therefrom. As in Fig. 2, a battery mounting part 30 for mounting the battery BAT is provided on the rear end part 64 of the housing 60. In Fig. 2, the position of the battery BAT attached to the battery mounting part 30 is shown by a dashed line for easier technical understanding.

[0042] The battery mounting part 30 has guide rails 32 and terminals 34. The battery mounting part 30 may further include a locking mechanism for restricting the falling of the battery BAT. The guide rails 32 are formed as projections extending in the up-down direction. The guide rails 32 are configured to fit into recessed rail receiving parts (not shown) of the battery BAT. The guide rails 32 define an attachment / removal direction DB in which the battery BAT, which is shown in Fig. 1. The battery BAT, which is attached to the battery mounting part 30, is electrically connected via the terminals 34 and can supply power to the motor 20.

[0043] The attachment / removal direction DB of the battery BAT is set to a direction crossing the central axis HX, which is the central axis of the grip part 76, provided that the battery BAT does not interfere with the main handle 70. In the example shown in Fig. 2, the attachment / removal direction DB is perpendicular to the hammer axis TX. Thus, the attachment / removal direction DB coincides with the up-down direction and is perpendicular to the central axis HX. A user can remove the battery from the battery mounting part 30 by pulling the battery BAT upward along the attachment / removal direction DB. Furthermore, the user can attach the battery BAT to the battery mounting part 30 by pushing the battery BAT downward along the attachment / removal direction DB. The user can attach and remove the battery BAT in the direction crossing the central axis HX of the grip part 76 in this way, so that the user can easily attach and remove the battery BAT with one hand even while holding the main handle 70 or the front handle 80 with the other hand.In another embodiment, the attachment / removal direction DB of the battery BAT may be set to a direction obliquely crossing the hammer axis TX, provided that the battery BAT does not interfere with the main handle 70. The battery BAT can be removed by pulling downward along the attachment / removal direction DB and attached by pushing upward.

[0044] As in Fig. 2, the battery mounting part 30 is arranged between both ends of the main handle 70 at the rear end part 64 of the housing 60. In the example shown in Fig. As shown in FIG. 2, the battery mounting part 30 is arranged between the first and second connecting parts 70L, 70R in the extending direction of the handle part 76. With such an arrangement that the battery BAT attached to the battery mounting part 30 is surrounded by the main handle 70, the battery BAT can be protected by utilizing the main handle 70. For example, the battery BAT is protected from impact when the power tool 100 is dropped.

[0045] As in Fig. 3, the battery mounting portion 30 is configured such that the hammer axis TX passes through the battery mounting portion 30. In this embodiment, the battery mounting portion 30 is disposed on a rear surface of the housing 60. With the battery BAT disposed on the hammer axis TX, the increase in size of the housing 60 in a radial direction crossing the hammer axis TX is reduced or prevented.

[0046] The structures of the elements arranged within the housing 60 will now be described with reference to Fig. 3 to 5. In this embodiment, as shown in Fig. 3, the housing 60 includes an inner housing 602 and an outer housing 604. The outer housing 604 houses the inner housing 602 and forms an outer shell of the housing 60. The main handle 70 and the front handle 80 are connected to the outer housing 604. The inner housing 602 houses the motor 20, a controller 40, a hammer mechanism 50, and a tool holder 90. The tool holder 90 removably holds the tool accessory TT in an insertion hole 92 formed in the front end portion 61 of the housing 60.

[0047] The motor 20 is driven by power supplied from the battery BAT attached to the battery mounting part 30. The motor 20 is a brushless DC motor (direct current motor) driven under the control of the controller 40. As shown in Fig. As shown in Fig. 3, the motor 20 is housed in the motor housing part 63 behind the hammer mechanism housing part 62 within the housing 60, so that the hammer axis TX passes through the motor 20. The motor axis MX of the motor 20 is arranged relatively close to the hammer axis TX, so that the power tool 100 can be reduced in size in the radial direction.

[0048] As in Fig. As shown in Figure 4, the motor 20 includes a motor body 22 having a stator and a rotor, a motor shaft 24, and a fan 26. The motor body 22 is disposed in the inner casing 602 within the motor housing portion 63. The motor shaft 24 rotates about the motor axis MX together with the rotor. A front end of the motor shaft 24 projects into the hammer mechanism housing portion 62. A first bevel gear 561 is provided at the front end of the motor shaft 24. The fan 26 rotates together with the motor shaft 24 and generates an airflow for cooling the motor body 22.

[0049] As in Fig. 3, the controller 40 is formed by a computer including a CPU as a processor and memories such as RAM and ROM. The controller 40 is configured to control the driving of the motor 20 and other various operations in the power tool 100. The controller 40 is disposed between the motor 20 and the grip portion 76 of the main handle 70 in the front-to-rear direction. The controller 40 is arranged within the housing 60 such that its surface direction crosses the motor axis MX. The controller 40 is housed within a rear end portion of the housing 60, in which a space can be easily formed, so that the controller 40 is efficiently arranged within the housing 60. In this embodiment, the controller 40 is arranged in the rear end portion 64 behind the motor housing portion 63 within the housing 60 and between the motor 20 and the battery mounting portion 30.Furthermore, the controller 40 is arranged such that the hammer axis TX passes through the controller 40. With such a configuration, the housing 60 can be reduced in size in the radial direction.

[0050] As in Fig. 4, the hammer mechanism 50 includes a hammer portion (impact portion) 52 and a crank portion 56. The crank portion 56 is configured to convert rotational motion of the motor shaft 24 into linear motion of a hammer element (impact element) 524 along the hammer axis TX and to transfer the kinetic energy of the rotational motion of the motor shaft 24 to the hammer element 524. The hammer portion 52 transfers the kinetic energy of the hammer element 524 from the crank portion 56 to the tool accessory TT.

[0051] The crank part 56 includes the first bevel gear 561, the second bevel gear 562, the crankshaft 564, a rod 568, and a piston 569. The first bevel gear 561 is provided at the front end of the motor shaft 24 and meshes with the second bevel gear 562 within the hammer mechanism housing part 62. The crankshaft 564 includes a body part 564B, a crank plate 564T, and a peripheral part 564W. The peripheral part 564W is a part of the crankshaft 564 that is continuous with the crank plate 564T about the rotation axis CX.

[0052] The second bevel gear 562 is provided on an outer periphery of the crankshaft 564. The second bevel gear 562 is integrally formed with the crankshaft 564. In this embodiment, the second bevel gear 562 is formed separately from the crankshaft 564, and an inner peripheral surface 562W of the second bevel gear 562 is secured to the peripheral part 564W of the crankshaft 564, for example, by press fitting, so that a single component part is formed that has a function of the crankshaft 564 and a function of the second bevel gear 562. The driving force of the engine 20 is efficiently transmitted via the crankshaft 564 and the second bevel gear 562. The crankshaft 564 is rotatably supported relative to the inner case 602 by a bearing 565 and rotates together with the second bevel gear 562 about the rotation axis CX. Thus, an axis of rotation of the second bevel gear 562 coincides with the axis of rotation CX of the crankshaft 564.The rotation axis CX is perpendicular to the motor axis MX and the hammer axis TX. A space 564S for arranging the bearing 565 is provided between the peripheral part 564W and the body part 564B under the crank plate 564T. By arranging the bearing 565 in the space 564S, the crankshaft 564, the bearing 565, and the second bevel gear 562 are arranged side by side in the radial direction of the crankshaft 564. With this arrangement, the size of the arrangement area of the crankshaft 564, the bearing 565, and the second bevel gear 562 in the axial direction of the rotation axis CX can be reduced. The second bevel gear 562 can be formed integrally with the crankshaft 564, for example, by casting.

[0053] Rotation of the motor shaft 24 is transmitted to the second bevel gear 562 and the crankshaft 564 via the first bevel gear 561. The second bevel gear 562 and the crankshaft 564 are rotated about the rotation axis CX perpendicular to the motor axis MX by rotation of the first bevel gear 561.

[0054] The crankshaft 564 transfers the kinetic energy from the engine 20 to the hammer part 52. A crank pin 566 is provided on the crank plate 564T of the crankshaft 564. A rod 568 is mounted on the crank pin 566 and connects the crank pin 566 and the piston 569.

[0055] The crank pin 566 is offset (eccentric) from the rotation axis CX. When the crankshaft 564 rotates, the crank pin 566 rotates about the rotation axis CX. The rod 568 is oscillated in the front-to-back direction perpendicular to the rotation axis CX by rotation of the crankshaft 564. Rotational motion of the crankshaft 564 is transmitted to the piston 569 via the rod 568.

[0056] The piston 569 is a generally cylindrical member. The piston 569 is arranged to slide along the hammer axis TX within a cylinder 520 formed in the inner housing 602. The piston 569 is configured to reciprocate in the front-to-back direction via the rod 568 in conjunction with the rotation of the crank pin 566.

[0057] The hammer part 52 includes the hammer element 524 and a firing pin 526. The hammer element 524 applies a hammer force to the tool accessory TT. The hammer element 524 is arranged such that it is slidable along the hammer axis TX within the cylinder 520. An air chamber SP, which functions as an air spring, is defined between the piston 569 and the hammer element 524 within the cylinder 520. The firing pin 526 is an intermediate element that transfers the kinetic energy of the hammer element 524 to the tool accessory TT. The firing pin 526 is arranged at the front of the hammer element 524 such that it is movable along the hammer axis TX.

[0058] When the piston 569 reciprocates in the front-to-back direction, the pressure within the air chamber SP fluctuates, and the hammer element 524 is displaced in the front-to-back direction within the cylinder 520 by the action of the air spring. Specifically, when the piston 569 moves forward, the distance between the piston 569 and the hammer element 524 decreases, so that air within the air chamber SP is compressed and the pressure within the cylinder 520 increases. The hammer element 524 is pushed forward at high speed by the action of the air spring and hammers (strikes, impacts) the firing pin 526.

[0059] The struck striker 526 transfers the kinetic energy of the hammer element 524 to the tool accessory TT. The tool accessory TT is then driven linearly along the hammer axis TX. In the power tool 100 of this embodiment, by utilizing the action of the air spring, vibration of the power tool 100 is reduced, and greater kinetic energy is transferred to the tool accessory TT compared to a tool in which the kinetic energy is mechanically transferred to the tool accessory TT.

[0060] When the piston 569 is moved rearward, the distance between the piston 569 and the hammer element 524 increases, so that air within the air chamber SP is expanded. Thus, the pressure within the cylinder 520 decreases, and the hammer element 524 is retracted rearward. The struck tool accessory TT comes into contact with a machining object and moves rearward together with the striking pin 526 due to a reaction force from the machining object. A similar hammering movement of the hammer mechanism 50 is repeated.

[0061] As in Fig. 4, the power tool 100 of this embodiment is configured such that the motor axis MX is arranged near the hammer axis TX. To this end, the motor axis MX is arranged such that it passes through the interior of the cylinder 520. In the example shown in Fig. 4, the motor axis MX of the motor shaft 24 is arranged slightly below the hammer axis TX and parallel to the hammer axis TX. Components from the motor 20, which is a driving source of kinetic energy, to the tool accessory TT are arranged substantially in a straight line by disposing the motor axis MX and the hammer axis TX close to each other, so that the hammer axis TX is located close to the center of gravity of the entire power tool 100. This improves the power tool 100 in operation. In another embodiment, the motor axis MX may coincide with the hammer axis TX. Alternatively, the motor axis MX may be arranged close to the hammer axis TX and above or to the left or right side of the hammer axis TX. Even with such a configuration, the power tool 100 is improved in operability by disposing the hammer axis TX close to the center of gravity of the entire power tool 100.

[0062] As in Fig. 5, in this embodiment, elastic members 606 are disposed between the inner casing 602 and the outer casing 604. Each of the elastic members 606 is a synthetic resin material, such as urethane or silicone. The elastic members 606 have, for example, a generally cuboid shape. The elastic members 606 are held in contact with the inner casing 602 and the outer casing 604. In the example shown in Fig.5, the housing 60 includes four elastic members 606. Specifically, two of the elastic members 606 are disposed at the front of the rotation axis CX, and the other two are disposed at the rear of the rotation axis CX in the front-to-rear direction of the housing 60. The two elastic members 606 at the front are disposed on the left and right sides of the hammer axis TX. Similarly, the two elastic members 606 at the rear are disposed on the left and right sides of the hammer axis TX.

[0063] The provision of the elastic members 606 between the inner housing 602 and the outer housing 604 reduces transmission of vibration from the inner housing 602, which is a vibration source, to the outer housing 604 during hammer movement. Furthermore, this provision also reduces play between the inner housing 602 and the outer housing 604 due to dimensional deviations of the inner housing 602 and the outer housing 604 during manufacturing. Any number (one, two, or more) of elastic members 606 can be provided. The elastic members 606 are not limited to a synthetic resin material but may be a metal material such as a metal spring. The shape of the elastic members 606 is not limited to a cuboid shape but may be any shape such as a rectangular parallelepiped shape, a spherical shape, and a columnar shape.The elastic elements 606 may be an annular member, such as an O-ring, arranged continuously around the circumference of the inner housing 602. B. Further embodiments:

[0064] (B1) The above-described embodiment is described using a shovel as an example of the tool accessory TT, but the tool accessory TT may be a tool other than a shovel. The tool accessory TT may be, for example, a so-called spatula or scraper used for scraping work on a processing object. In scraping work, similar to earthwork, the power tool 100 can be pressed against a processing object, so that the power tool 100 of the above-described embodiment is suitable for scraping work. The tool accessory TT may be, like a needle scaler, a needle gun scaler, and a needle gun, for scraping rust or coatings from the surface of a workpiece by pressing a plurality of needle-like members against the processing object while reciprocating them.The shovel can be either standardized according to the Japanese Industrial Standard (JIS) or non-standardized. The shovel may have a part on which the user's foot can be placed. (B2)

[0065] Given the nature of the present disclosure and the above-described embodiments, the following aspects may be provided. These aspects may be applied in combination with the power tool 100 of the above-described embodiments, the above-described modifications, or the claimed invention. (Aspect 1) The hammer axis passes through the motor. (Aspect 2) The front handle is mounted in such a way that its position relative to the housing is adjustable, and a bearing axis of the front handle is perpendicular to the hammer axis. (Aspect 3) The hammer axis passes through the control. (Aspect 4) The control is located at the rear of the motor in the housing. (Aspect 5) The controller is located between the motor and the battery mounting part. List of reference symbols

[0066] 20: Motor, 22: Motor body, 24: Motor shaft, 26: Fan wheel, 30: Battery mounting part, 32: Guide rail, 34: Connector, 40: Controller, 50: Hammer mechanism, 52: Hammer part, 56: Crank part, 60: Housing, 61: Front end part, 62: Hammer mechanism housing part, 63: Motor housing part, 64: Rear end part, 70: Main handle, 70L: First connecting part, 70R: Second connecting part, 71: First extension part, 72: Second extension part, 76: Grip part, 77: Switch trigger, 80: Front handle, 80L, 80R: Connecting part, 86: Grip part, 90: Tool holder, 92: Insertion hole, 100: Power tool, 502: Cylinder, 524: Hammer element, 526: firing pin, 561: first bevel gear, 562: second bevel gear, 562W: inner peripheral surface, 564: crankshaft, 564B: body part, 564T: crank plate, 564W: peripheral part, 565: bearing, 566: crank pin, 568: rod, 569: piston, 602: inner casing, 604: outer casing, 606: elastic element, BAT: battery, LT: light-emitting part, SP: air chamber,TT: Tool accessories, QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 5 002 134 A

[0002]

Claims

[1] Power tool, with a motor having a motor shaft rotating about a motor axis, a hammer mechanism comprising a cylinder and a hammer element adjacent to an air chamber defined within the cylinder, and configured to convert a rotary motion of the motor shaft into a linear motion of the hammer element along a predetermined hammer axis by utilizing an action of the air spring of the air chamber, and a housing that houses the motor and the hammer mechanism, in which the motor axis is parallel to the hammer axis and passes through the inside of the cylinder. [2] Power tool according to claim 1, further comprising a main handle having (i) a grip portion configured to be held by a user, (ii) a first connecting portion connecting a first end of the grip portion to the housing, and (iii) a second connecting portion connecting a second end of the grip portion to the housing, in which the hammer axis passes between the first end and the second end of the handle portion when the power tool is viewed in a direction perpendicular to the hammer axis. [3] A power tool according to claim 2, wherein the hammer mechanism further comprises (i) a second bevel gear meshing with a first bevel gear provided on the motor shaft, and (ii) a crankshaft formed integrally with the second bevel gear and rotating together with the second bevel gear. [4] A power tool according to claim 3, wherein an extending direction of the handle part is (i) parallel to a plane perpendicular to a rotational axis of the second bevel gear and (ii) crosses the hammer axis. [5] Power tool according to one of claims 2 to 4, with a controller that controls the engine, in which the main handle is connected to a rear end part of the housing, and the control (i) is accommodated in the housing and (ii) is arranged between the motor and the handle part in an extension direction of the hammer axis. [6] Power tool according to one of claims 1 to 5, in which the housing further comprises a battery mounting part to which a battery for supplying power to the motor is removably attachable, and the hammer axis is arranged such that it passes through the battery mounting part. [7] Power tool according to claim 6, further comprising a main handle having (i) a grip portion configured to be held by a user, (ii) a first connecting portion connecting a first end of the grip portion to the housing, and (iii) a second connecting portion connecting a second end of the grip portion to the housing, in which the battery mounting part is arranged between the first connecting part and the second connecting part on the housing in an extension direction of the handle part. [8] Power tool according to claim 1, further comprising a main handle having (i) a grip portion configured to be held by a user, (ii) a first connecting portion connecting a first end of the grip portion to the housing, and (iii) a second connecting portion connecting a second end of the grip portion to the housing, in which the housing has an inner housing which houses the motor and the hammer mechanism, and an outer housing which houses the inner housing, the main handle is connected to the outer casing, and an elastic member in contact with the inner casing and the outer casing is arranged between the inner casing and the outer casing. [9] Power tool according to claim 3 or according to any one of claims 4 to 8 directly or indirectly dependent on claim 3, further comprising a front handle configured to be held by a user in which if an extension direction of the hammer axis defines a front-back direction of the power tool, the main handle is connected to the housing at a point rearward of the rotational axis of the second bevel gear, and the front handle is connected to the housing at a point in front of the axis of rotation of the second bevel gear. [10] The power tool according to any one of claims 1 to 9, further comprising a light emitting part configured to emit light toward a working area.

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