Work equipment

Abstract

The present invention improves workability while achieving reduction in size. In vibration reduction mechanisms 80 of a hammer drill 10, weight members 90 are disposed at locations, in an inner case 72, that overlap a ring gear 56 in the right-left direction and vertical direction when viewed from the front-back direction. Weight springs 96 are disposed so as to be displaced downward from the centers of gravity G of the weight members 90 when viewed from the front-back direction. More specifically, in each of the weight members 90, a spring mounting part 94 having the corresponding weight spring 96 mounted thereto and a weight part 92 serving as a weight section in which the center of gravity G is located are disposed so as to be displaced from each other in the vertical direction, and the weight part 92 extends upward from the spring mounting part 94. Accordingly, it is possible to reduce the physical size of the weight members 90 and eventually reduce the physical size of the hammer drill 10.

Description

Technical Field

[0001] The present invention relates to a working machine.

Background Art

[0002] In the working machine described in Patent Document 1 below, a gear housing is provided inside an outer housing that constitutes the outer shape of the working machine. Further, a power transmission mechanism is provided inside the gear housing, and a striking force in the front-rear direction is applied to the tip tool by the power transmission mechanism. The working machine also has a vibration reduction mechanism that reduces the vibration generated by the power transmission mechanism. Thereby, for example, the workability for an operator can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above working machine, the vibration reduction mechanism is disposed between the gear housing and the outer housing. Specifically, the vibration reduction mechanisms are respectively disposed on the outer sides in the left-right direction of the gear housing. For this reason, the size of the working machine tends to increase.

[0005] In consideration of the above facts, an object of the present invention is to provide a working machine that can improve workability while achieving miniaturization.

Means for Solving the Problems

[0006] One or more embodiments of the present invention include a drive source, a tip tool, and a cylindrical member that is connected to the drive source and the tip tool and has an axial direction in the front-rear direction It is formed in such a way that it rotates by the drive source, thereby imparting rotational force to the tip tool. a cylindrical member a rotating shaft is positioned below the cylindrical member, meshes with the cylindrical member, and rotates in response to the driving force of the drive source, thereby imparting rotational force to the cylindrical member.An impact element that, by being operated within the cylindrical member by the drive source, applies the forward and backward striking force to the tip tool, A power transmission unit comprising, The device comprises at least a case for housing the cylindrical member, and a vibration reducing unit housed inside the case for reducing vibrations in the front-rear direction that occur in the case, wherein the vibration reducing unit includes a guide member extending in the front-rear direction, a weight member supported by the guide member so as to be movable in the front-rear direction, and a biasing member for biasing the weight member in the front-rear direction, wherein, in a front-rear view, at least a portion of the weight member is located below the upper end of the cylindrical member and above the lower end of the cylindrical member, and at least a portion of the weight member is located to the left of the right end and to the right of the left end of the cylindrical member. ,before The center of gravity of the weight member is the same as that of the cylindrical member. So that it is located below the upper end and above the lower end of the cylindrical member. Left and right line up The work machine is arranged such that the biasing member is positioned vertically offset from the center of gravity of the weight member when viewed in the front-to-back direction.

[0007] One or more embodiments of the present invention are: It is connected to the aforementioned rotating shaft so as to be able to rotate integrally with the aforementioned rotating shaft, The driving force of the aforementioned drive source via the rotating shaft and the cylindrical member The work machine further comprises a power transmission member that transmits power to the tip tool, wherein, in a view from the front and rear, the power transmission member extends in the left-right direction below the cylindrical member, and at least a portion of the weight member is sandwiched in the up-down direction by the cylindrical member and the power transmission member.

[0008] One or more embodiments of the present invention are that the power transmission member is the vertical direction This is a work machine that has its axis oriented and is a gear that transmits rotational force to the cylindrical member.

[0009] One or more embodiments of the present invention are work machines in which the weight member has a curved surface extending along the circumferential direction of the cylindrical member.

[0010] One or more embodiments of the present invention are such that the weight member is the vertical direction This is a work machine supported by a pair of guide members arranged at a distance from each other.

[0011] One or more embodiments of the present invention are work machines in which the biasing member is a coil spring attached to the guide member.

[0012] One or more embodiments of the present invention are provided inside the case, and the vibration reducing parts are provided relative to the cylindrical member. Left and right direction These are work machines positioned on one side and the other side, respectively.

[0013] One or more embodiments of the present invention are work machines in which the weight members in a pair of vibration reduction units are connected by a weight connecting unit.

[0014] One or more embodiments of the present invention are working machines in which the vibration reduction unit has holders that support both longitudinal ends of the guide member, and the holders are pressed against the wall surface of the case by the biasing force of the biasing member. [Effects of the Invention]

[0015] According to one or more embodiments of the present invention, it is possible to improve workability while miniaturizing the product. [Brief explanation of the drawing]

[0016] [Figure 1] This is a longitudinal cross-sectional view from the right side showing a hammer drill according to this embodiment. [Figure 2] Figure 1 is a perspective view taken from the left rear, showing the housing of the power transmission mechanism and vibration reduction mechanism in the inner case. [Figure 3] Figure 2 is a top view showing the power transmission mechanism and vibration reduction mechanism housed in the inner case. [Figure 4]It is a cross-sectional view seen from the rear showing the state of accommodation of the power transmission mechanism and the vibration reduction mechanism shown in FIG. 3 in the inner case (cross-sectional view taken along line 4-4 of FIG. 3). [Figure 5] It is a perspective view seen from the left rear obliquely, showing an enlarged view of the state of accommodation of the vibration reduction mechanism shown in FIG. 2 in the inner case. [Figure 6] (A) is a perspective view showing an enlarged view of the right vibration reduction mechanism shown in FIG. 5, and (B) is a side view seen from the left side of the vibration reduction mechanism shown in (A). [Figure 7] (A) is a perspective view showing the weight member of the vibration reduction mechanism shown in FIG. 6(A), (B) is a side view seen from the left side of the weight member shown in (A), and (C) is a rear view seen from the rear side of the weight member shown in (A). [Figure 8] It is a side view seen from the left side showing Modification 1 of the vibration reduction mechanism used in the hammer drill according to the present embodiment. [Figure 9] It is a side view seen from the left side showing Modification 2 of the vibration reduction mechanism used in the hammer drill according to the present embodiment. [Figure 10] It is a perspective view seen from the left rear obliquely showing Modification 3 of the vibration reduction mechanism used in the hammer drill according to the present embodiment. [Figure 11] It is a cross-sectional view corresponding to FIG. 4 showing the state of accommodation of the vibration reduction mechanism shown in FIG. 10 in the inner case.

Mode for Carrying Out the Invention

[0017] The hammer drill 10 as a work machine according to this embodiment will be described with reference to Figures 1 to 7. The hammer drill 10 is configured as a tool for performing drilling and other operations on a workpiece. The arrows UP, FR, and RH shown in the drawings as appropriate indicate the upper, front, and right sides of the hammer drill 10, respectively. In the following description, when using the directions of up / down, front / back, and left / right, unless otherwise specified, they refer to the up / down, front / back, and left / right directions of the hammer drill 10. The front / back direction corresponds to the first direction of the present invention, the up / down direction corresponds to the second direction of the present invention, and the left / right direction corresponds to the third direction of the present invention. The lower side corresponds to one side of the second direction of the present invention. Furthermore, hatching has been omitted in the drawings as appropriate for convenience.

[0018] As shown in Figure 1, the hammer drill 10 comprises a housing 12, a motor 34 housed within the housing 12 as a drive source, and a power transmission mechanism 40 as a power transmission unit that transmits the driving force of the motor 34 to the cutting tool T. The hammer drill 10 also has a mode switching mechanism 66, and by operating the switching lever 67 of the mode switching mechanism 66, the transmission path to the cutting tool T in the power transmission mechanism 40 is switched, so that the hammer drill 10 switches between a hammer mode that applies impact force to the cutting tool T, and a hammer drill mode that applies rotational force and impact force to the cutting tool T. The hammer drill 10 also has a pair of left and right vibration reduction mechanisms 80 (see Figures 2 and 3) as vibration reduction units, which absorb vibrations in the front-rear direction that occur when the hammer drill 10 is in operation. The various components of the hammer drill 10 will be described below.

[0019] (Regarding Housing 12) Housing 12 is formed in a hollow shape and constitutes the outer casing of the hammer drill 10. Housing 12 has a main body housing 14 and a handle 16 positioned on the rear side (one side in the front-rear direction) of the main body housing 14. The main body housing 14 extends in the front-rear direction, and the rear end of the main body housing 14 protrudes downward. The main body housing 14 is composed of a plurality of housing members.

[0020] The handle 16 extends vertically, and its upper and lower ends are connected to the main body housing 14 by a vibration isolation mechanism 20, so that the handle 16 can move relative to the main body housing 14 in the front-rear direction. The vibration isolation mechanism 20 has a hinge connection portion 21 that connects the lower end of the handle 16 to the main body housing 14, and the hinge connection portion 21 is rotatably connected to the rear lower end of the main body housing 14 with the left-right direction as the axial direction. The vibration isolation mechanism 20 has an elastic connection portion 22 that connects the upper end of the handle 16 to the main body housing 14. The elastic connection portion 22 is made of an elastic material such as an elastomer, and is formed in a cylindrical and bellows shape with the front-rear direction as the axial direction, and both front-rear ends of the elastic connection portion 22 are integrally formed with the handle 16 and the main body housing 14.

[0021] Furthermore, the vibration isolation mechanism 20 has a vibration isolation spring 23 configured as a compression coil spring, which is positioned within the elastic connecting portion 22 and biases the handle 16 and the main body housing 14 outward in the front-rear direction. In addition, the vibration isolation mechanism 20 has a stopper mechanism (not shown) that holds the handle 16 in the non-retracted position shown in Figure 1. When machining a workpiece, the handle 16 is pushed forward, causing it to displace forward from the non-retracted position.

[0022] The upper and lower middle portion of the handle 16 is configured as a gripping portion 16A for the operator to grasp. A trigger 26 is provided at the upper part of the gripping portion 16A. The trigger 26 is formed in a substantially elongated block shape that extends in the vertical direction and is exposed to the front from the gripping portion 16A so as to be operable. The lower end of the trigger 26 is rotatably connected to the handle 16 with the left-right direction as the axial direction, and the trigger 26 is configured to be pullable to the rear. A switch 28 is provided inside the handle 16 behind the trigger 26. When the operator pulls the trigger 26, the switch 28 is turned on. The switch 28 is electrically connected to a control unit 30 provided at the lower end of the main body housing 14 and outputs an output signal to the control unit 30 according to the operating state of the trigger 26.

[0023] A power cord 32 is provided at the lower end of the handle 16. The power cord 32 extends downward from the handle 16 and is configured to be connectable to a commercial power supply. The power cord 32 is electrically connected to the control unit 30, and power is supplied to the control unit 30 from the commercial power supply via the power cord 32.

[0024] (Regarding the motor 34) The motor 34 is configured as a three-phase brushless motor and is housed in the lower part of the main body housing 14 and positioned in front of the control unit 30. The motor 34 includes a drive shaft 34A whose axial direction is vertical, a substantially cylindrical rotor 34B fixed to the drive shaft 34A, and a substantially cylindrical stator 34C positioned radially outward of the rotor 34B. The lower end of the drive shaft 34A is rotatably supported by a bearing 35, and the upper end portion of the drive shaft 34A is rotatably supported by a bearing 36. A pinion gear 34A1 is formed at the upper end of the drive shaft 34A. The motor 34 is electrically connected to the control unit 30 and is driven by the control of the control unit 30.

[0025] (Regarding the power transmission mechanism 40) The power transmission mechanism 40 is composed of a crank mechanism 42, a rotating mechanism 47, and a power supply mechanism 53. The power transmission mechanism 40 is housed in an inner case 72, which is housed in the upper part of the main body housing 14. In the power transmission mechanism 40, the crank mechanism 42 and the rotating mechanism 47 constitute the lower part of the power transmission mechanism 40, and the power supply mechanism 53 constitutes the upper part of the power transmission mechanism 40, with the crank mechanism 42 and the rotating mechanism 47 arranged side by side in the front-rear direction. The configuration of the inner case 72 will be described first, followed by a description of each component of the power transmission mechanism 40.

[0026] (Regarding the inner case 72) As shown in Figures 1 to 5, the inner case 72 is composed of a case body 73 and a case cover 74, and the case cover 74 is assembled to the case body 73 to form the inner case 72. The rear part of the case body 73 is composed of a gear case section 73A, and the gear case section 73A is formed in a substantially concave shape that is open to the upper side. The front part of the case body 73 is composed of a cylindrical case section 73B, and the cylindrical case section 73B is formed in a substantially cylindrical shape with the front-rear direction as the axial direction and extends forward from the upper part of the gear case section 73A. The case cover 74 is formed in a substantially plate shape with the vertical direction as the thickness direction and is assembled to the upper opening of the gear case section 73A to close the opening. Furthermore, the bearing 36 that supports the drive shaft 34A of the aforementioned motor 34 is fixed to the bottom wall of the gear case portion 73A, and the pinion gear 34A1 of the drive shaft 34A is positioned inside the lower end of the gear case portion 73A.

[0027] (Regarding the crank mechanism 42) As shown in Figure 1, the crank mechanism 42 is housed in the rear part of the gear case 73A. The crank mechanism 42 includes a crankshaft 43 and a crank gear 44. The crankshaft 43 is formed in a substantially cylindrical shape with a bottom that is open to the bottom and is located behind the pinion gear 34A1 of the motor 34, with the lower end of the crankshaft 43 fixed to the bottom wall of the gear case 73A. The crank gear 44 is formed in a substantially cylindrical shape with its axial direction in the vertical direction and is rotatably supported on the crankshaft 43 via a bearing 45. A gear portion is formed on the outer circumference of the lower end of the crank gear 44, and this gear portion meshes with the pinion gear 34A1 of the motor 34. The upper end of the crank gear 44 is provided with a connecting shaft 44A that protrudes upward, and the connecting shaft 44A is positioned eccentrically with respect to the center of the crank shaft 43.

[0028] (Regarding the rotating mechanism 47) As shown in Figures 1 and 4, the rotating mechanism 47 is housed in the front part of the gear case 73A. The rotating mechanism 47 has a rotating shaft 48 and a transmission gear 50 as a power transmission member. The rotating shaft 48 is formed in a substantially cylindrical shape with its axial direction in the vertical direction and is positioned in front of the pinion gear 34A1 of the motor 34. The lower part of the rotating shaft 48 is rotatably supported by the bottom wall of the gear case 73A via a bearing 49. A bevel gear 48A is formed at the upper end of the rotating shaft 48.

[0029] The transmission gear 50 is formed in a substantially disc shape with its thickness oriented vertically, and is integrally rotatably connected to the upper end portion of the rotating shaft 48. The transmission gear 50 has a slip clutch 51, which connects the transmission gear 50 to the rotating shaft 48. Specifically, a recess opening downwards is formed on the lower surface of the transmission gear 50, and the slip clutch 51 is positioned in this recess to connect the transmission gear 50 to the rotating shaft 48. A gear portion is formed on the outer circumference of the transmission gear 50, and this gear portion meshes with the pinion gear 34A1 of the motor 34. Furthermore, when a rotational torque exceeding a predetermined value is applied to the slip clutch 51, the connection between the rotating shaft 48 and the transmission gear 50 by the slip clutch 51 is released. In other words, the slip clutch 51 is configured as a so-called torque limiter mechanism, and is configured to prevent overloading of the motor 34 by the slip clutch 51. Furthermore, the transmission gear 50 constitutes the outermost part in the left-right direction of the power transmission mechanism 40. In other words, in the power transmission mechanism 40, the transmission gear 50 is configured as the largest component in the left-right direction. As a result, the maximum left-right dimension of the inner case 72 (gear case portion 73A) is set by the diameter of the transmission gear 50.

[0030] (Regarding the power supply mechanism 53) As shown in Figures 1 to 4, the power supply mechanism 53 is composed of a cylinder 54, a retainer sleeve 55, a ring gear 56 as a cylindrical member, a clutch 58, a piston 60, a striking element 63, and an intermediate element 64.

[0031] The cylinder 54 and retainer sleeve 55 are formed in a substantially cylindrical shape with the front-to-back direction as the axial direction and are arranged coaxially. The front end of the cylinder 54 is fitted into the rear end of the retainer sleeve 55, so that the cylinder 54 and retainer sleeve 55 are connected so that they can rotate together as a single unit. The cylinder 54 and retainer sleeve 55 are housed in the upper part of the gear case portion 73A and the cylindrical case portion 73B of the inner case 72. More specifically, the rear end of the cylinder 54 is positioned above the rotating mechanism portion 47 and in front of the connecting shaft 44A in the crank mechanism portion 42. On the other hand, the front end of the retainer sleeve 55 protrudes forward from the inner case 72. The cylinder 54 and retainer sleeve 55 are rotatably supported by the inner case 72 and the main housing 14 via bearings. The tip tool T is attached to the front end of the retainer sleeve 55 and protrudes forward from the front end of the main housing 14.

[0032] The ring gear 56 is formed in a substantially cylindrical shape with its axial direction in the front-rear direction, and is externally fitted to the rear end portion of the cylinder 54, and is rotatably supported by the cylinder 54. More specifically, the ring gear 56 is positioned above the transmission gear 50 and housed in the gear case portion 73A. A bevel gear 56A is formed at the rear end of the ring gear 56, and the bevel gear 56A meshes with the bevel gear 48A of the rotating shaft 48 in the rotating mechanism portion 47. In a longitudinal cross-sectional view, the rear end of the ring gear 56 is bent radially outward in a substantially crank shape, and protrudes radially outward compared to other parts of the ring gear 56. Furthermore, the axis AL1 of the aforementioned transmission gear 50 passes through the axis AL2 of the ring gear 56 (cylinder 54). Furthermore, the outermost diameter of the ring gear 56 is set to be smaller than the diameter of the transmission gear 50 (see Figure 4), and the ring gear 56 constitutes the outermost part in the left-right direction at the upper part (power application mechanism section 53) of the power transmission mechanism 40.

[0033] The clutch 58 is formed in a substantially cylindrical shape with its axial direction in the front-rear direction and is externally fitted onto the cylinder 54 at the rear of the ring gear 56. The clutch 58 is spline-caught with the cylinder 54. That is, the clutch 58 is connected to the cylinder 54 so as to be able to rotate integrally with it and move relative to it in the front-rear direction. The front end of the clutch 58 is positioned radially inward of the rear end of the ring gear 56 and engages with the ring gear 56 in the circumferential direction. As a result, the driving force of the motor 34 is transmitted to the cylinder 54 by the rotating mechanism 47, the ring gear 56, and the clutch 58, causing the cylinder 54 and the retainer sleeve 55 to rotate and impart rotational force to the tip tool T. On the other hand, when the clutch 58 is moved to the rear by the mode switching mechanism 66, which will be described later, the engagement between the clutch 58 and the ring gear 56 is released, and the transmission of driving force from the rotating mechanism 47 to the cylinder 54 is interrupted.

[0034] As shown in Figure 1, the piston 60 is formed in a substantially bottomed cylindrical shape that is open to the rear and is inserted into the rear of the cylinder 54 so as to be movable relative to it in the front-rear direction. The piston 60 is also provided with a piston connecting shaft 61 whose axis is oriented in the vertical direction. The front end of a piston rod 62, which extends in the front-rear direction, is rotatably connected to the piston connecting shaft 61, and the rear end of the piston rod 62 is rotatably connected to the connecting shaft 44A of the crank mechanism 42. As a result, the driving force of the motor 34 is transmitted to the piston 60 by the crank mechanism 42 and the piston rod 62, causing the piston 60 to reciprocate in the front-rear direction.

[0035] The striking element 63 is formed in a substantially cylindrical shape with its axis oriented in the front-rear direction, and is inserted into the cylinder 54 so as to be movable relative to it in the front-rear direction. The striking element 63 is positioned spaced apart in front of the piston 60, and the space between the piston 60 and the striking element 63 within the cylinder 54 is configured as an air chamber 54A.

[0036] The meson 64 is formed in a substantially cylindrical shape with its axial direction in the front-rear direction and is inserted into the retainer sleeve 55 so as to be able to move relative to it in the front-rear direction. The meson 64 is positioned adjacent to the front of the striker 63. As a result, when the piston 60 moves forward and the pressure in the air chamber 54A increases, the striker 63 and meson 64 move forward, and a striking force along the front-rear direction is applied to the tip tool T.

[0037] (Regarding the mode switching mechanism 66) The mode switching mechanism 66 is composed of a switching lever 67 and a switching arm 69.

[0038] The selector lever 67 is formed in a substantially bottomed cylindrical shape that is open to the bottom, and is positioned at the rear end of the main body housing 14, while also being operably exposed upward from the main body housing 14. A lever shaft 68 is fixed to the center of the selector lever 67, and the lever shaft 68 is formed in a substantially cylindrical shape with its axis oriented vertically, and protrudes downward from the selector lever 67. The lever shaft 68 is rotatably supported by the case cover 74 of the inner case 72.

[0039] The switching arm 69 is formed in a substantially elongated shape that extends in the front-rear direction. The front end of the switching arm 69 is connected to the clutch 58 of the power supply mechanism 53, and the rear end of the switching arm 69 is connected to the lever shaft 68 via the arm connecting shaft 70. The arm connecting shaft 70 is positioned eccentrically with respect to the central axis of the lever shaft 68. As a result, when the switching lever 67 rotates, the switching arm 69 is displaced in the front-rear direction. Specifically, in the hammer drill mode of the hammer drill 10, the switching arm 69 is positioned as shown in Figure 1, and the ring gear 56 and the clutch 58 are engaged. On the other hand, although not shown in the figure, in the hammer mode of the hammer drill 10, rotating the switching lever 67 displaces the switching arm 69 to the rear, and the engagement between the ring gear 56 and the clutch 58 is released.

[0040] (Regarding the vibration reduction mechanism 80) As shown in Figures 3 and 4, the left and right pair of vibration reduction mechanisms 80 are housed at both ends in the left-right direction of the gear case portion 73A of the inner case 72. Specifically, the left and right pair of vibration reduction mechanisms 80 are housed above the transmission gear 50 in the gear case portion 73A and within the space S on both sides in the left-right direction of the ring gear 56. The left and right pair of vibration reduction mechanisms 80 are configured symmetrically with respect to the left-right central portion of the inner case 72. For this reason, the following description will focus on the right vibration reduction mechanism 80, and the description of the left vibration reduction mechanism 80 will be omitted as appropriate.

[0041] As shown in Figures 2 to 7, the vibration reduction mechanism 80 is composed of a pair of front and rear holders 82, an upper guide shaft 84 and a lower guide shaft 86 as guide members, a weight member 90, and a pair of front and rear weight springs 96 as biasing members.

[0042] (Regarding the holders 82) The pair of holders 82 are formed in a substantially rectangular plate shape with the front-to-back direction as the plate thickness direction and the up-to-down direction as the longitudinal direction, and constitute both front-to-back ends of the vibration reduction mechanism 80. The lower ends of the holders 82 engage with the inner case 72 in the front-to-back and left-to-right directions, and the upper ends of the holders 82 engage with the case cover 74 in the front-to-back and left-to-right directions, thereby fixing them to the inner case 72. The front holder 82 is biased forward by a front weight spring 96, which will be described later, and the rear holder 82 is biased backward by a rear weight spring 96, so that the pair of holders 82 are pressed against the wall surface of the case body 73. This maintains the fixed state of the holders 82 (vibration reduction mechanism 80).

[0043] A pair of upper bearing portions 82A are formed on the upper part of the front and rear holders 82. The upper bearing portions 82A are formed in a substantially cylindrical shape with the front-rear direction as the axial direction and protrude inward from the holders 82 in the front-rear direction. A lower bearing portion 82B is formed on the lower part of the pair of holders 82. The lower bearing portion 82B is formed in a substantially cylindrical shape with the front-rear direction as the axial direction, similar to the upper bearing portion 82A, and protrudes inward from the holders 82 in the front-rear direction. Furthermore, the positions of the upper bearing portions 82A and lower bearing portions 82B in the left-right direction are set so that, when viewed from the front-rear direction, the lower bearing portion 82B is positioned between the left and right pair of upper bearing portions 82A.

[0044] (Regarding the upper guide shaft 84 and lower guide shaft 86) The upper guide shaft 84 and lower guide shaft 86 are formed in a substantially cylindrical shape with the front-rear direction as the axial direction. The longitudinal ends of the upper guide shaft 84 are fitted into the upper bearing portion 82A on the left-right outer side (i.e., the right side) of the holder 82, and the upper guide shaft 84 is held by the pair of front and rear holders 82. Similarly, the longitudinal ends of the lower guide shaft 86 are fitted into the lower bearing portion 82B of the holder 82, and the lower guide shaft 86 is held by the pair of front and rear holders 82. In other words, the lower guide shaft 86 is positioned closer to the left-right inner side (towards the ring gear 56) relative to the upper guide shaft 84. Also, when viewed from the front-rear direction, the upper guide shaft 84 is positioned slightly below the axis AL2 of the ring gear 56. Furthermore, ring dampers 88 are externally fitted to both front-rear ends of the upper guide shaft 84. The ring damper 88 is made of an elastic material such as rubber and is configured as a member that mitigates the collision between the weight member 90 (described later) and the upper bearing portion 82A of the holder 82.

[0045] (Regarding the weight member 90) The weight member 90 is composed of a weight portion 92 which constitutes the upper part of the weight member 90 and a spring mounting portion 94 which constitutes the lower part of the weight member 90.

[0046] The weight portion 92 is oriented with its thickness in the left-right direction and is formed in a roughly inverted T-shape when viewed from the left-right direction. An upper guide hole 92A is formed through the lower end of the weight portion 92 in the front-rear direction. The upper guide shaft 84 is inserted into the upper guide hole 92A, and the weight portion 92 is supported by the upper guide shaft 84 so as to be movable relative to it in the front-rear direction. Furthermore, when viewed from the front-rear direction, the center of gravity G of the weight member 90 (see Figure 4) is positioned to overlap with the weight portion 92. More specifically, when viewed from the front-rear direction, the center of gravity G of the weight member 90 is located near the upper guide hole 92A.

[0047] The spring mounting portion 94 is formed in a plate shape with the front-to-rear direction as the thickness direction and extends downward from the front-to-rear center of the weight portion 92. The spring mounting portion 94 also has a pair of front and rear mounting cylinder portions 94A for attaching the weight spring 96, which will be described later. The mounting cylinder portions 94A are formed in a cylindrical shape with the front-to-rear direction as the axial direction and protrude outward from the spring mounting portion 94 in the front-to-rear direction. The inside of the mounting cylinder portion 94A is configured as a lower guide hole 94B, and the lower guide hole 94B penetrates in the front-to-rear direction so that the insides of the pair of front and rear mounting cylinder portions 94A are in communication. The lower guide shaft 86 is inserted into the lower guide hole 94B, and the spring mounting portion 94 is supported on the lower guide shaft 86 so that it can move relative to it in the front-to-rear direction. As a result, in the weight member 90, the spring mounting portion 94 for attaching the weight spring 96 and the weight portion 92 which functions as a weight are positioned offset from each other in the vertical direction.

[0048] Here, the weight member 90 is positioned close to the right side of the ring gear 56, and in the left-right direction, the weight member 90 and the ring gear 56 overlap almost entirely (see Figure 4). Specifically, the upper end of the weight member 90 is positioned below the uppermost end of the ring gear 56, and the lower end of the weight member 90 is positioned slightly below the lowest end of the ring gear 56. Furthermore, the position of the weight member 90 in the front-rear direction is set so that, when viewed from above, the entire weight member 90 overlaps with the transmission gear 50.

[0049] Furthermore, the outer shape of the spring mounting portion 94 is formed in a substantially circular shape centered on the lower guide hole 94B when viewed from the front-rear direction, and the outer circumferential surface of the weight portion 92 and the outer circumferential surface of the spring mounting portion 94 are smoothly connected. Specifically, a curved surface 90A is formed on the inner side surface of the weight member 90 in the left-right direction (i.e., the left side surface, which is the surface radially opposite to the ring gear 56). When viewed from the front-rear direction, the curved surface 90A is curved in an arc shape centered on the axis AL2 of the ring gear 56, and is formed on the lower part of the weight portion 92 and the upper part of the spring mounting portion 94, and is smoothly connected to the lower surface of the spring mounting portion 94.

[0050] In other words, in the weight member 90, a portion of the spring mounting portion 94 extends to the left of the weight portion 92 and is positioned to fit between the ring gear 56 and the transmission gear 50 in space S. To put it another way, the weight member 90 extends vertically along the circumferential direction of the ring gear 56 on the right side of the ring gear 56. As a result, in the vertical direction, the outermost part of the ring gear 56 (the part where the bevel gear 56A is formed) and a portion of the weight member 90 overlap. Furthermore, the left and right outer side surface 90B of the weight member 90 is formed in a planar shape along a plane perpendicular to the left and right direction and is smoothly connected to the lower surface of the spring mounting portion 94. The side surface 90B of the weight member 90 is positioned close to the left and right side surfaces of the gear case portion 73A.

[0051] (Regarding the weight springs 96) The front and rear pair of weight springs 96 are configured as compression coil springs. The weight springs 96 are positioned on the front-rear outer side of the spring mounting portion 94 on the weight member 90 and are mounted on the lower guide shaft 86. Specifically, the rear end of the front weight spring 96 is fitted onto the front mounting cylinder portion 94A, and the front end of the front weight spring 96 is fitted onto the lower bearing portion 82B of the front holder 82. On the other hand, the front end of the rear weight spring 96 is fitted onto the rear mounting cylinder portion 94A, and the rear end of the rear weight spring 96 is fitted onto the lower bearing portion 82B of the rear holder 82. As a result, the weight springs 96 are positioned at a position shifted downward relative to the weight portion 92 (center of gravity G of the weight member 90). In other words, in a view in the front-to-back direction, the center AL3 of the weight spring 96 is positioned at a different location from the center of gravity G of the weight member 90. To put it another way, in a view in the front-to-back direction, the center of gravity G of the weight member 90 is positioned outside the range of the weight spring 96. Furthermore, although the lower guide shaft 86 is inserted through the inside of the weight spring 96, a gap equal to the thickness of the mounting cylinder portion 94A and the lower bearing portion 82B is provided radially between the lower guide shaft 86 and the weight spring 96.

[0052] The front weight spring 96 biases the spring mounting portion 94 towards the rear, and the rear weight spring 96 biases the spring mounting portion 94 towards the front, so that the weight member 90 is held in a position at the center of the upper guide shaft 84 and the lower guide shaft 86 in the front-rear direction. The radius of the weight spring 96 is set to be slightly smaller than the radius of the spring mounting portion 94 of the weight member 90, so that when viewed from the front-rear direction, the weight spring 96 does not protrude beyond the spring mounting portion 94.

[0053] (Effects and Effects) Next, the effects and functions of this embodiment will be described.

[0054] In the hammer drill mode of the hammer drill 10, the ring gear 56 and the clutch 58 are engaged by the switching arm 69 of the mode switching mechanism 66. As a result, when the motor 34 is driven by the operator pulling the trigger 26, the crank mechanism 42 and the rotation mechanism 47 are activated, and impact force and rotation force are applied to the tip tool T from the power supply mechanism 53.

[0055] On the other hand, in hammer mode of the hammer drill 10, the clutch 58 is displaced to the rear by the switching arm 69 of the mode switching mechanism 66, and the engagement between the ring gear 56 and the clutch 58 is released. As a result, when the motor 34 is driven by the operator pulling the trigger 26, the crank mechanism 42 is activated, and only the impact force is applied from the power supply mechanism 53 to the tip tool T.

[0056] In both the hammer drill mode and the hammer mode of the hammer drill 10, the power transmission mechanism 40 is activated, and a forward-backward impact force is applied to the tip tool T. As a result, vibrations generated when the power transmission mechanism 40 is activated are transmitted to the inner case 72.

[0057] In the hammer drill 10, a vibration reduction mechanism 80 is provided inside the inner case 72. The vibration reduction mechanism 80 has a weight member 90, which is supported so as to be able to move relative to the front and rear by a pair of upper and lower guide shafts 84 and lower guide shafts 86. The weight member 90 is also biased in the front and rear direction by a pair of front and rear weight springs 96. As a result, when the power transmission mechanism 40 is operated, the weight member 90 vibrates in the front and rear direction, and the vibration energy transmitted to the inner case 72 can be absorbed by the vibration reduction mechanism 80. Therefore, the vibration transmitted to the operator is reduced, and the workability of the hammer drill 10 can be improved.

[0058] Furthermore, the weight member 90 is positioned within the inner case 72 so as to overlap with the ring gear 56 in the left-right and up-down directions when viewed from the front-rear direction, and the weight spring 96 is positioned so as to be offset downward from the center of gravity G of the weight member 90 when viewed from the front-rear direction. Specifically, the weight member 90 has a spring mounting portion 94 to which the weight spring 96 is attached, and a weight portion 92 that functions as a weight where the center of gravity G is located, which are positioned offset vertically, with the weight portion 92 extending upward from the spring mounting portion 94. This makes it possible to reduce the size of the weight member 90, and consequently, the size of the hammer drill 10.

[0059] The following will explain this point in comparison with the comparative example's weight. The comparative example's weight is formed in a cylindrical shape with the front-to-back direction as its axial direction. That is, in the comparative example's weight, the weight portion that functions as a counterweight and the spring mounting portion for attaching the weight spring 96 are not misaligned in the vertical direction. When the comparative example's weight member is movably connected to the upper guide shaft 84 or the lower guide shaft 86, and biased by a pair of front and rear weight springs 96 that sandwich the comparative example's weight member from the outside in the front-to-back direction, it is necessary to increase the size of the weight member in order to ensure sufficient weight in the weight member. For example, if the size of the weight member in the comparative example is increased in the radial direction, it is necessary to increase the size of the inner case 72 in the left-to-right and up-to-down directions. Also, for example, if the size of the weight member in the comparative example is increased in the front-to-back direction, it is necessary to increase the size of the inner case 72 in the front-to-back direction. This may result in an increase in the overall size of the hammer drill 10.

[0060] In contrast, in this embodiment, as described above, the weight member 90 is positioned within the inner case 72 so as to overlap with the ring gear 56 in the left-right and up-down directions when viewed from the front-rear direction. Furthermore, the weight member 90 has a spring mounting portion 94 to which the weight spring 96 is attached, and a weight portion 92 that functions as a weight, which are positioned offset in the up-down direction. That is, the weight member 90 can be made to extend vertically along the circumferential direction of the ring gear 56 on the left-right outer side of the ring gear 56. Therefore, the size of the weight member 90 can be made smaller than that of the weight member in the comparative example above, and the size of the hammer drill 10 can also be made smaller. As a result, the hammer drill 10 can be made smaller while improving workability.

[0061] Another comparative example is a configuration in which the vibration reduction mechanism 80 is provided outside the inner case 72. In this other comparative example, the wall surface of the inner case 72 is interposed between the space inside the inner case 72 where the power transmission mechanism 40 is housed and the space where the vibration reduction mechanism 80 is housed, making it difficult to position the weight member 90 so that it overlaps with the ring gear 56 in the vertical and horizontal directions. In addition, since an outer wall is provided separately outside the space where the vibration reduction mechanism 80 is housed, the size of the hammer drill 10 may increase. In contrast, in this embodiment, since both the vibration reduction mechanism 80 and the power transmission mechanism 40 are housed inside the inner case 72, the weight member 90 can be positioned so that it overlaps with the ring gear 56 in the vertical and horizontal directions, and there is no need to provide an outer wall other than the inner case 72, making it possible to miniaturize the hammer drill 10.

[0062] Furthermore, in the weight member 90, the weight portion 92 is positioned on the left-right outer side of the ring gear 56 (cylinder 54), and the spring mounting portion 94 is positioned below the weight portion 92. More specifically, when viewed from the front-rear direction, the weight portion 92, where the center of gravity G of the weight member 90 is located, is positioned slightly below the axis AL2 of the ring gear 56 (cylinder 54), and the spring mounting portion 94 is positioned below the weight portion 92. As a result, compared to a configuration in which the positions of the weight portion 92 and the spring mounting portion 94 of the weight member 90 are inverted vertically, the center of gravity G of the weight member 90 can be positioned closer to the axis AL2 in the vertical direction. In other words, compared to a configuration in which the weight portion 92 is movably connected to the lower guide shaft 86 and the spring mounting portion 94 is movably connected to the upper guide shaft 84, the amount of vertical offset of the center of gravity G of the weight member 90 from the axis AL2 can be reduced. This allows the center of gravity G of the weight member 90 to be positioned on the left-right outer side of the cylinder 54 that houses the piston 60 and the striking element 63, which impart forward and backward striking force to the tip tool T. Therefore, the vibration reduction effect of the vibration reduction mechanism 80 can be enhanced.

[0063] Furthermore, the power transmission mechanism 40 has a transmission gear 50. When viewed from the front-rear direction, the transmission gear 50 extends in the left-right direction below the ring gear 56, and at least a portion of the weight member 90 is sandwiched vertically between the ring gear 56 and the transmission gear 50. Specifically, the spring mounting portion 94 of the weight member 90 protrudes further toward the ring gear 56 than the weight portion 92, and this protruding portion is sandwiched vertically between the ring gear 56 and the transmission gear 50. This allows the spring mounting portion 94 and a portion of the weight spring 96 to be positioned by utilizing the space S of the gear case portion 73A between the ring gear 56 and the transmission gear 50. Therefore, while ensuring the diameter (spring diameter) of the weight spring 96, it is possible to suppress the weight spring 96 from protruding outward in the left-right direction from the weight member 90.

[0064] Furthermore, a curved surface 90A is formed on the inner surface of the weight member 90 in the left-right direction, and the curved surface 90A is formed in an arc shape that extends along the circumferential direction of the ring gear 56. This makes it possible to position the weight member 90 close to the ring gear 56 while ensuring the weight of the weight member 90. As a result, it is possible to effectively contribute to reducing the size of the weight member 90 in the left-right direction.

[0065] Furthermore, the weight member 90 is supported by a pair of upper guide shafts 84 and lower guide shafts 86 so as to be movable relative to each other in the front-rear direction. This allows the weight member 90 to be positioned along the circumferential direction of the ring gear 56 while stabilizing its posture.

[0066] Furthermore, the weight spring 96 is a compression coil spring attached to the lower guide shaft 86. This allows the lower guide shaft 86 to stabilize the posture of the weight spring 96, while the weight spring 96 biases the weight member 90 in the front-rear direction.

[0067] Furthermore, in the hammer drill 10, a pair of left and right vibration reduction mechanisms 80 are provided in the inner case 72, and the vibration reduction mechanisms 80 are positioned on both the left and right sides relative to the ring gear 56. This allows the vibrations transmitted to the inner case 72 when the power transmission mechanism 40 is operating to be absorbed in a balanced manner by the pair of vibration reduction mechanisms 80.

[0068] Furthermore, the vibration reduction mechanism 80 has a pair of front and rear holders 82 that support both longitudinal ends of the upper guide shaft 84 and the lower guide shaft 86, and the holders 82 are pressed against the gear case portion 73A of the inner case 72 by the biasing force of the weight spring 96. In this way, the biasing force of the weight spring 96 that biases the weight member 90 in the front and rear directions can be utilized to maintain a good fixed state of the holders 82 to the inner case 72.

[0069] Furthermore, since the vibration reduction mechanism 80 is also located within the inner case 72 that houses the power transmission mechanism 40, the power transmission mechanism 40 can be maintained at the same time as the inner case 72 is opened for maintenance, resulting in improved maintainability of the hammer drill 10. Moreover, since the lubricant such as grease applied to the power transmission mechanism 40 to lubricate it can be scattered to the vibration reduction mechanism 80 during operation, the power transmission mechanism 40 is also lubricated, making it less prone to wear and tear, and improving reliability.

[0070] (Modified versions of the vibration reduction mechanism 80) Next, modified versions of the vibration reduction mechanism 80 will be described.

[0071] (Modified Example 1 of Vibration Reduction Mechanism 80) Modified Example 1 of the vibration reduction mechanism 80 will be described below with reference to Figure 8. Modified Example 1 of the vibration reduction mechanism 80 is configured in the same way as the vibration reduction mechanism 80 of this embodiment, except for the points shown below. Figure 8 shows the vibration reduction mechanism 80 located on the right side, and in Figure 8, the same reference numerals are used for parts that are configured in the same way as the vibration reduction mechanism 80 of this embodiment.

[0072] In the first modified example of the vibration reduction mechanism 80, the upper guide shaft 84 is omitted, and the weight member 90 is supported only by the lower guide shaft 86. The lower guide shaft 86 is formed in a non-circular shape when viewed from its longitudinal direction. In this modified example, the lower guide shaft 86 is formed in a substantially track shape in cross-section.

[0073] In the weight member 90, the upper guide hole 92A is omitted, and the lower guide hole 94B is formed in an elongated shape corresponding to the outer shape of the lower guide shaft 86. As a result, the weight member 90 is connected to the lower guide shaft 86 so that it can move relative to it in the front-rear direction but cannot rotate relative to it.

[0074] Furthermore, in the modified example 1 of the vibration reduction mechanism 80, similar to this embodiment, the weight member 90 is arranged radially outward of the ring gear 56, along the circumferential direction of the ring gear 56, and the spring mounting portion 94 to which the weight spring 96 is attached is extended toward the ring gear 56, so that the weight spring 96 can be positioned lower to the center of gravity G of the weight member 90 and toward the ring gear 56. Therefore, in the modified example 1 of the vibration reduction mechanism 80, it is possible to improve workability while miniaturizing the hammer drill 10.

[0075] Furthermore, in the modified example 1 of the vibration reduction mechanism 80, the upper guide shaft 84 is omitted. This reduces the number of parts and assembly man-hours, and contributes to cost reduction of the vibration reduction mechanism 80.

[0076] (Modified Version 2 of the Vibration Reduction Mechanism 80) Modified Version 2 of the vibration reduction mechanism 80 will be described below with reference to Figure 9. Modified Version 2 of the vibration reduction mechanism 80 is configured in the same way as the vibration reduction mechanism 80 of this embodiment, except for the points shown below. Figure 9 shows the vibration reduction mechanism 80 located on the right side, and in Figure 9, the same reference numerals are used for parts that are configured in the same way as the vibration reduction mechanism 80 of this embodiment.

[0077] In the second modified example of the vibration reduction mechanism 80, the lower guide shaft 86 is omitted, and the weight member 90 is supported only by the upper guide shaft 84. The upper guide shaft 84 is formed in a non-circular shape when viewed along its longitudinal direction, similar to the lower guide shaft 86 in the first modified example of the vibration reduction mechanism 80.

[0078] In the weight member 90, the lower guide hole 94B is omitted, and the upper guide hole 92A is formed in an elongated shape corresponding to the outer shape of the upper guide shaft 84. As a result, the weight member 90 is connected to the upper guide shaft 84 so that it can move relative to it in the front-rear direction but cannot rotate relative to it.

[0079] Furthermore, in the modified example 2 of the vibration reduction mechanism 80, similar to the embodiment, the weight member 90 is arranged radially outward of the ring gear 56, along the circumferential direction of the ring gear 56, and the spring mounting portion 94 to which the weight spring 96 is attached is extended toward the ring gear 56, so that the weight spring 96 can be positioned lower to the center of gravity G of the weight member 90 and toward the ring gear 56. Therefore, in the modified example 2 of the vibration reduction mechanism 80, it is possible to improve workability while miniaturizing the hammer drill 10.

[0080] Furthermore, in the modified example 2 of the vibration reduction mechanism 80, the upper guide shaft 84 is omitted. This reduces the number of parts and assembly man-hours, and contributes to cost reduction of the vibration reduction mechanism 80.

[0081] (Modification 3 of the vibration reduction mechanism 80) Hereinafter, modification 3 of the vibration reduction mechanism 80 will be described with reference to Figures 10 and 11. Modification 3 of the vibration reduction mechanism 80 is configured in the same way as the vibration reduction mechanism 80 of this embodiment, except for the points shown below. In Figures 10 and 11, the same reference numerals are used for parts that are configured in the same way as the vibration reduction mechanism 80 of this embodiment.

[0082] In the modified example 3 of the vibration reduction mechanism 80, a connecting arm 98 is provided as a weight connecting part for connecting the weight members 90 of the left and right vibration reduction mechanisms 80. The connecting arm 98 is positioned above the ring gear 56 and is formed in a substantially semicircular disc shape that opens downward along the circumferential direction of the ring gear 56. Both longitudinal ends of the connecting arm 98 are connected to the upper ends of the weight members 90. As a result, in the modified example 3 of the vibration reduction mechanism 80, the left and right pair of vibration reduction mechanisms 80 operate as a single unit.

[0083] Furthermore, in the third modified example of the vibration reduction mechanism 80, similar to this embodiment, the weight member 90 is positioned radially outward of the ring gear 56, along the circumferential direction of the ring gear 56, and the spring mounting portion 94 to which the weight spring 96 is attached is extended toward the ring gear 56, allowing the weight spring 96 to be positioned lower to the center of gravity G of the weight member 90 and closer to the ring gear 56. Therefore, in the third modified example of the vibration reduction mechanism 80, the hammer drill 10 can be miniaturized while improving workability.

[0084] Furthermore, in the modified example 3 of the vibration reduction mechanism 80, the left and right pair of vibration reduction mechanisms 80 can be operated as a single unit by the connecting arm 98. Also, since the left and right weight members 90 are connected by the connecting arm 98, the total weight of the left and right weight members 90 can be made heavier compared to this embodiment. Therefore, for example, the total weight of the weight members 90 can be adjusted to correspond to the resonant frequency during operation of various hammer drills. Consequently, vibrations generated during operation can be absorbed in accordance with various hammer drills. [Explanation of Symbols]

[0085] 10...Hammer drill (working tool), 34...Motor (drive source), 40...Power transmission mechanism (power transmission section), 50...Transmission gear (power transmission member), 56...Ring gear (cylindrical member), 72...Inner case (case), 80...Vibration reduction mechanism (vibration reduction section), 82...Holder, 84...Upper guide shaft (guide member), 86...Lower guide shaft (guide member), 90...Weight member, 90A...Curved surface, 96...Weight spring (biasing member), 98...Connecting arm (weight connecting section), G...Center of gravity of weight member, T...Tip tool

Claims

1. Power source and Cutting tools and, A power transmission unit comprising: a cylindrical member connected to the drive source and the end tool, formed in a cylindrical shape with the front-rear direction as its axial direction, which rotates by the drive source to impart rotational force to the end tool; a rotating shaft positioned below the cylindrical member, meshing with the cylindrical member, which rotates in response to the driving force of the drive source to impart rotational force to the cylindrical member; and a striking element which operates within the cylindrical member by the drive source to impart striking force in the front-rear direction to the end tool; A case for housing at least the cylindrical member, A vibration reduction unit housed inside the case reduces the vibrations in the front-to-back direction that occur in the case, Equipped with, The vibration reduction unit is The guide member extending in the front-rear direction, A weight member supported by the guide member so as to be movable in the front-rear direction, A biasing member that biases the weight member in the front-rear direction, It consists of, The weight members are arranged such that, in a view in the front-to-back direction, at least a portion of the weight member is located below the upper end of the cylindrical member and above the lower end of the cylindrical member, and at least a portion of the weight member is located to the left of the right end and to the right of the left end of the cylindrical member, and the weight members are arranged side by side in the left-to-right direction such that the center of gravity of the weight members is located below the upper end of the cylindrical member and above the lower end of the cylindrical member. The biasing member is positioned in a work machine that is offset vertically from the center of gravity of the weight member when viewed in the front-to-back direction.

2. The power transmission member is further connected to the rotating shaft so as to be rotatable integrally with the rotating shaft and transmits the driving force of the drive source to the tip tool via the rotating shaft and the cylindrical member, The work machine according to claim 1, wherein, in the front-to-back view, the power transmission member extends in the left-to-right direction below the cylindrical member, and at least a portion of the weight member is sandwiched in the up-to-down direction by the cylindrical member and the power transmission member.

3. The work machine according to claim 2, wherein the power transmission member is a gear whose vertical direction is axial and which transmits rotational force to the cylindrical member.

4. The work machine according to claim 1, wherein the weight member has a curved surface that extends along the circumferential direction of the cylindrical member.

5. The work machine according to claim 1, wherein the weight member is supported by a pair of guide members arranged to be spaced apart in the vertical direction.

6. The work machine according to claim 1, wherein the biasing member is a coil spring attached to the guide member.

7. The work machine according to claim 1, wherein a pair of vibration reducing units are provided inside the case, and the vibration reducing units are arranged on one side and the other side in the left-right direction relative to the cylindrical member.

8. The work machine according to claim 7, wherein the weight members in a pair of vibration reduction sections are connected by a weight connecting section.

9. The work machine according to any one of claims 1 to 8, wherein the vibration reduction unit has holders that support both longitudinal ends of the guide member, and the holders are pressed against the wall surface of the case by the biasing force of the biasing member.

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