Work equipment

Abstract

Provided is a work machine in which a counterweight is appropriately supported, thereby avoiding deterioration of workability. This work machine comprises: a motor 20; a plunger 30 that is reciprocated in the front-rear direction by driving of the motor; a crankshaft 51 that is rotated around an axis extending in the up-down direction by driving of the motor; a counterweight 80 that is driven in the front-rear direction by the rotation of the crankshaft so as to cancel vibrations caused by the reciprocation of the plunger 30; a transmission mechanism (a gear 50, the crankshaft 51, and a connector 70) that converts a rotational driving force of the motor into a driving force for the plunger and the counterweight, and transmits the driving force to the plunger and the counterweight; and a gear case (a transmission mechanism housing part 61 and a lid part 62) that houses the transmission mechanism, and elastically supports the counterweight in the left-right direction.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a saber saw (reciprocating saw) as a working machine. In this working machine, a plunger reciprocates in the front-rear direction by driving a motor, and a blade provided at the tip of the plunger reciprocates to cut an object.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the working machine described in Patent Document 1, a counterweight is operated to reduce vibration in the front-rear direction. However, the operation of the counterweight may cause other vibrations and abnormal noises, which may hinder workability.

[0005] In view of the above problems, an object of the present invention is to provide a working machine in which workability is not impaired by appropriately supporting a counterweight.

Means for Solving the Problems

[0006] A working machine according to an embodiment includes a motor, a plunger that can be attached with a tool and reciprocates in the front-rear direction by driving the motor, and a rotation about an axis extending in the vertical direction by driving the motor It also has an eccentric portion that revolves around the aforementioned axis.A rotating body, an eccentric portion provided on the rotating body and revolving around the axis, and a counterweight connected to the eccentric portion, which reciprocates in the front-rear direction to cancel out vibrations caused by the reciprocating motion of the plunger by transmitting a forward biasing force from the eccentric portion that moves forward and a rearward biasing force from the eccentric portion that moves rearward. Including the eccentric portion and the rotating body, The system comprises a transmission mechanism for transmitting the rotational driving force of the motor to the plunger and the counterweight, a transmission mechanism case for housing the transmission mechanism, and an elastic body for elastically supporting the counterweight in the left-right direction. The elastic body is supported by the counterweight or the transmission mechanism case. The elastic body supports the counterweight left Movement to the right is buffered. [Effects of the Invention]

[0007] In one embodiment of the work machine, vibrations caused by the movement of the counterweight are suppressed by the elastic body, so work efficiency is not impaired. [Brief explanation of the drawing]

[0008] [Figure 1] This is a left side view of a work machine according to one embodiment. [Figure 2] This is a partial cross-sectional view of the left side of the work machine. [Figure 3] This is a perspective view of the development of the transmission mechanism. [Figure 4] This is a plan view showing the left-right tilt of the counterweight. [Figure 5] This is a cross-sectional left side view showing the inclination of the counterweight in the front-to-back direction. [Modes for carrying out the invention]

[0009] Hereinafter, an implement according to an embodiment of the present invention will be described with reference to the drawings. In Figures 1 and 2, the front-rear direction and the up-down direction are the directions shown in the figures. The direction perpendicular to the front-rear direction and the up-down direction (i.e., the direction perpendicular to the plane of the paper) is referred to as the left-right direction. The front-rear direction is an example of a first direction. The up-down direction and the left-right direction are examples of a second direction. The second direction is a direction perpendicular to the first direction.

[0010] In the work implement 10, as shown in Figure 2, the plunger 30 is reciprocated in the forward and backward direction by the drive of the motor 20. The work implement 10 according to this embodiment is a reciprocating saw, in which a blade 32 is attached to the front side of the plunger 30, and the blade 32 reciprocates in the forward and backward direction to cut the object. First, Figure 1 Referring to Figure 3, the outline of the work machine 10 will be explained.

[0011] As shown in Figure 1, the work machine 10 is equipped with a housing 11 made of metal and synthetic resin. The housing 11 can be divided into two parts, left and right. The housing 11 is provided with a plunger housing 12, a motor housing 13, a handle 14, a trigger 15, a mounting section 16, a base 19, and the like.

[0012] The plunger housing 12 is cylindrical in shape and extends in the front-to-back direction. The motor housing 13 is cylindrical in shape and extends downward from the lower part of the plunger housing 12. The handle 14 is shaped to extend downward from the rear of the plunger housing 12. The handle 14 is equipped with a trigger 15. The operator grasps the handle 14 and operates the trigger 15.

[0013] Mounting sections 16 are provided at the bottom of the motor housing 13 and the handle 14. A battery pack 17 is mounted on the mounting section 16. The battery pack 17 supplies power to the motor 20. A controller 18 is provided inside the motor housing 13 (see Figure 2).

[0014] When the operator operates the trigger 15, the operation of the trigger 15 is detected by the trigger switch, and a trigger operation signal is transmitted from the trigger switch to the controller 18. When receiving the trigger operation signal, the controller 18 performs control to operate the motor 20.

[0015] A base 19 is provided in front of the plunger housing portion 12. The blade 32 penetrates through the base 19. The base 19 is movable in the front-rear direction and tiltable with respect to the plunger housing portion 12. The position and angle of the base 19 are adjusted by moving or tilting the base 19 according to the object. By performing the cutting operation with the base 19 having its position and angle adjusted pressed against the object, the blade 32 can be smoothly reciprocated.

[0016] As shown in FIG. 2, a gear case 60 is provided inside the plunger housing portion 12. The gear case 60 is composed of a lower transmission mechanism housing portion 61 and an upper lid portion 62.

[0017] The transmission mechanism housing portion 61 extends in the front-rear direction, is closed at the lower side, and is open at the upper side. The transmission mechanism housing portion 61 is made of metal. A motor shaft hole 61a extending in the vertical direction is formed at the rear portion of the transmission mechanism housing portion 61. A central shaft 61b extending in the vertical direction is provided at the middle portion of the transmission mechanism housing portion 61. An abutting surface 61c extending in the front-rear direction is formed at the front portion of the transmission mechanism housing portion 61.

[0018] The lid portion 62 is a thin plate shape extending in the front-rear direction. The lid portion 62 is made of metal. Therefore, the lid portion 62 has flexibility. The lid portion 62 seals the opening of the transmission mechanism housing portion 61.

[0019] The plunger 30 is accommodated in the gear case 60. The plunger 30 is a cylindrical shape extending in the front-rear direction. The plunger 30 is made of metal. The plunger 30 is supported by the first roller 46 and the second roller 47 and is reciprocable in the front-rear direction.

[0020] The first roller 46 is an example of the first support portion. The first support portion is arranged on one side of the plunger 30 in the orthogonal direction orthogonal to the front-rear direction. The first roller 46 of the present embodiment is arranged above the plunger 30. The first roller 46 is made of resin.

[0021] The second roller 47 is an example of the second support portion. The second support portion is arranged on the other side of the plunger 30 in the orthogonal direction orthogonal to the front-rear direction. The second roller 47 of the present embodiment is arranged below the plunger 30. The second roller 47 is made of resin.

[0022] The first roller 46 is rotatably supported by the first shaft 48. The second roller 47 is rotatably supported by the second shaft 49. The first shaft 48 and the second shaft 49 are made of metal. The first shaft 48 and the second shaft 49 are non-rotatably supported by the holder 40.

[0023] As shown in FIG. 3, the holder 40 includes a right member 41, a left member 42, and a connecting member 43 that connects the right member 41 and the left member 42. Since the right member 41, the left member 42, and the connecting member 43 of the holder 40 are configured as an integral single member, the manufacturing cost of the holder 40 can be reduced. The holder 40 is made of metal. Returning to FIG. 2, the lower surface of the holder 40 abuts against the contact surface 61c of the transmission mechanism housing portion 61. The upper surface of the holder 40 abuts against the lower surface of the lid portion 62.

[0024] A blade holder 31 is provided on the front side of the plunger 30. The blade holder 31 is a tool gripping portion. The blade 32 is gripped by the blade holder 31. The blade 32 is an example of a tool and is a saw blade in the present embodiment. The blade 32 reciprocates in the front-rear direction together with the plunger 30 to cut an object.

[0025] A dust guard 33 is provided at the front of the gear case 60. An O-ring 34 is provided at the front of the gear case 60. These dust guard 33 and O-ring 34 prevent chips and other debris generated by cutting the object from entering the inside of the gear case 60.

[0026] The motor housing 13 houses the motor 20. The motor 20 includes a stator 22, a rotor 24, and a motor shaft 20a, etc.

[0027] The gear case 60 houses a gear 50 and a connector 70. The gear 50 is disc-shaped. The gear 50 is made of metal. The gear 50 is supported by a central shaft 61b within the transmission mechanism housing 61. A damper 54 and a thrust washer 55 are positioned between the gear 50 and the transmission mechanism housing 61. Numerous steel balls 56 are rotatably arranged within the thrust washer 55. The steel balls 56 are in contact with the lower surface of the gear 50. The gear 50 is rotatable on the steel balls 56 around the central shaft 61b.

[0028] A crankshaft 51 is provided protruding from the upper surface of the gear 50. As shown in Figure 3, the crankshaft 51 has a first eccentric shaft 51a at one end, a second eccentric shaft 51b at the other end, and a connecting rod 51c that connects the first eccentric shaft 51a and the second eccentric shaft 51b. The first eccentric shaft 51a is eccentric from the central shaft 61b. The lower end of the first eccentric shaft 51a is embedded in and fixed to the gear 50. The second eccentric shaft 51b is eccentric from the central shaft 61b and the first eccentric shaft 51a. The second eccentric shaft 51b is floating above the upper surface of the gear 50.

[0029] A needle bearing 52 is attached to the first eccentric shaft 51a. The needle bearing 52 is rotatable relative to the first eccentric shaft 51a. A sleeve 53 is attached to the second eccentric shaft 51b. The sleeve 53 is rotatable relative to the second eccentric shaft 51b. The crankshaft 51 corresponds to the rotating body of the present invention. The second eccentric shaft 51b corresponds to the eccentric portion of the present invention.

[0030] A connector 70 is provided above the gear 50. The connector 70 is made of metal. In the center of the connector 70, left and right An elongated hole 70a extending in the direction is formed. A needle bearing 52 is engaged with the elongated hole 70a, and the needle bearing 52 slides within the elongated hole 70a.

[0031] A plunger sleeve 71 is attached to the front of the connector 70. The plunger sleeve 71 secures the rear end of the plunger 30 to the connector 70. The left and right sides of the connector 70 are supported by sliding bearings 72.

[0032] The first eccentric shaft 51a is connected to the plunger 30 via a needle bearing 52 and a connector 70. The connector 70 is reciprocable in the front-rear direction together with the plunger 30.

[0033] The gear 50, crankshaft 51, and connector 70 are examples of a transmission mechanism. The transmission mechanism converts the rotational driving force of the motor 20 into reciprocating driving force and transmits it to the plunger 30. The gear case 60 is an example of a transmission mechanism case. The transmission mechanism case houses the transmission mechanism. The transmission mechanism housing section 61 is an example of a first case. The lid section 62 is an example of a second case.

[0034] A spacer 75 is provided above the connector 70. The spacer 75 is immovable. A counterweight 80 is provided above the spacer 75. The counterweight 80 is driven by the motor 20 to counteract vibrations caused by the reciprocating motion of the plunger 30. The counterweight 80 is made of metal. An elongated hole 80a extending in the left-right direction is formed in the center of the counterweight 80. A sleeve 53 is engaged with the elongated hole 80a, and the sleeve 53 slides within the elongated hole 80a.

[0035] Multiple grooves are formed in the counterweight 80. More specifically, the counterweight 80 has side grooves 80b and top grooves 80c. Steel balls 81 are arranged inside the side grooves 80b and top grooves 80c. The steel balls 81 are an example of rolling elements.

[0036] The side grooves 80b are formed on both the left and right sides of the counterweight 80. More specifically, side grooves 80b are formed at two locations on the front and rear of the left side. Although not shown in the figure, side grooves 80b are also formed at two locations on the front and rear of the right side. In other words, side grooves 80b are provided at four locations on the sides of the counterweight 80. Furthermore, steel balls 81 are inserted into each of the side grooves 80b. The steel balls 81 inserted into each side groove 80b are capable of rolling within the side groove 80b.

[0037] The top grooves 80c are formed on the upper surface of the counterweight 80. More specifically, there are two top grooves 80c, one at the front and one at the rear. A steel ball 81 is inserted into each top groove 80c. The steel balls 81 inserted into each top groove 80c are capable of rolling within the top groove 80c.

[0038] Weight guides 82 and dampers 83 are positioned on both the left and right sides of the counterweight 80. The weight guides 82 and dampers 83 are attached to the transmission mechanism housing 61 and are immovable. The weight guides 82 and dampers 83 are examples of sliding support parts. The sliding support parts elastically support the counterweight 80 so that it can slide. The dampers 83 are examples of elastic bodies. In this embodiment, the dampers 83 are made of rubber. A projection is formed on the dampers 83, and this projection is inserted into a hole in the weight guide 82, preventing the weight guide 82 and dampers 83 from shifting in the front-rear direction.

[0039] The second eccentric shaft 51b engages with the counterweight 80 via the sleeve 53. The gear 50, crankshaft 51, and connector 70, which are an example of the transmission mechanism, convert the rotational driving force of the motor 20 into a reciprocating driving force for the counterweight 80 and transmit it to the counterweight 80.

[0040] Referring to Figure 3, the assembly state of each component to the gear case, which consists of a transmission mechanism housing 61 and a lid 62, will be described. Each component is arranged sequentially from the bottom upwards of the transmission mechanism housing 61 and is assembled to the gear case by being covered with the lid 62.

[0041] First, the motor 20 consists of a motor holder 21, a stator 22, a fan guide 23, and a rotor 24. The motor shaft 20a of the motor 20 is inserted into the motor shaft hole 61a provided in the transmission mechanism housing 61.

[0042] A damper 54 and a thrust washer 55 are arranged inside the transmission mechanism housing 61, and a number of steel balls 56 are arranged inside the thrust washer 55. A gear 50 is arranged on top of the steel balls 56, and a central shaft 61b provided in the transmission mechanism housing 61 is inserted into the center of the gear 50. The motor shaft 20a is in contact with the side of the gear 50. The center of gravity G of the work machine 10 is located behind the central shaft 61b. The center of gravity G is located below the plunger 30.

[0043] A connector 70, to which a sliding bearing 72 is attached, is positioned above the gear 50. Of the crankshaft 51 protruding from the upper surface of the gear 50, the second eccentric shaft 51b and the connecting rod 51c protrude above the connector 70 through an elongated hole 70a formed in the connector 70. Of the crankshaft 51, the first eccentric shaft 51a is located within the elongated hole 70a, and a needle bearing 52 attached to the first eccentric shaft 51a is engaged with the elongated hole 70a.

[0044] A first shaft 48 and a second shaft 49 are inserted through the holder 40, and the first roller 46 and the second roller 47 are rotatably supported by the first shaft 48 and the second shaft 49. The holder 40 is positioned inside the transmission mechanism housing 61, and the lower surface of the holder 40 is in contact with the contact surface 61c of the transmission mechanism housing 61.

[0045] The plunger 30 is inserted through the dust guard 33 and the O-ring 34, and then through the transmission mechanism housing 61. The plunger 30 is inserted between the first roller 46 and the second roller 47. The plunger 30 is fixed to the connector 70 by the plunger sleeve 71.

[0046] A metal plate 76 and a spacer 75 are positioned on top of the connector 70. Of the crankshaft 51 protruding from the upper surface of the gear 50, the connecting rod 51c is at the same height as the spacer 75, and the second eccentric shaft 51b protrudes above the spacer 75. The metal plate 76 supports the sliding bearing 72 to prevent it from moving upward.

[0047] The left and right weight guides 82 and dampers 83 are positioned on the spacer 75. The weight guides 82 are made by bending a plate-shaped member into an L-shape in cross-section. The weight guides 82 have vertical wall portions 82a extending vertically (and front and back) and horizontal wall portions 82b extending left and right (and front and back). Two steel balls 81 are positioned on the left weight guide 82, and two steel balls 81 are also positioned on the right weight guide 82. The steel balls 81 positioned on the weight guides 82 are in contact with the vertical wall portion 82a and the horizontal wall portion 82b, respectively. A counterweight 80 is positioned between the left and right weight guides 82. As a result, the four steel balls 81 positioned on the left and right weight guides 82 are positioned in the four side grooves 80b formed on the counterweight 80. A sleeve 53 attached to the second eccentric shaft 51b is engaged with the elongated hole 80a. Two steel balls 81 are inserted into two upper surface grooves 80c formed in the counterweight 80.

[0048] A packing 63 and a cover 62 are placed on the transmission mechanism housing 61, and the cover 62 is screwed to the transmission mechanism housing 61, thereby sealing the gear case 60 as shown in Figure 2. The lower surface of the cover 62 abuts against the upper surface of the holder 40 and also abuts against the steel ball 81 inserted into the upper groove 80c.

[0049] The reciprocating motion of the plunger 30 and counterweight 80 driven by the motor 20 will now be described. When the motor 20 is activated, the gear 50 in contact with the motor shaft 20a rotates about the central axis 61b, and the crankshaft 51 protruding from the gear 50 also rotates about the central axis 61b.

[0050] As the crankshaft 51 rotates, the first eccentric shaft 51a revolves around the central shaft 61b, and the needle bearing 52 attached to the first eccentric shaft 51a also revolves around the central shaft 61b. Furthermore, as the needle bearing 52 revolves, it moves while rotating within the elongated hole 70a. As a result, the connector 70 is moved back and forth, and the plunger 30 connected to the connector 70 is also moved back and forth.

[0051] As the crankshaft 51 rotates, the second eccentric shaft 51b also revolves around the central shaft 61b, and the sleeve 53 attached to the second eccentric shaft 51b also revolves around the central shaft 61b. Furthermore, as the sleeve 53 revolves, it moves while rotating within the elongated hole 80a. As a result, the counterweight 80 is reciprocated in the front-rear direction.

[0052] In this embodiment, the first eccentric shaft 51a and the second eccentric shaft 51b, which are provided at both ends of the connecting rod 51c, are positioned at 180° apart with respect to the central axis 61b. Therefore, when the plunger 30 moves forward, the counterweight 80 moves backward, and when the plunger 30 moves backward, the counterweight 80 moves forward. In other words, the plunger 30 and the counterweight 80 operate in opposite phases.

[0053] The tilt of the counterweight 80 during operation will be explained with reference to Figures 4 and 5. Note that the actual tilt of the counterweight 80 is slight, but it is exaggerated in both figures.

[0054] Figure 4 is a plan view showing the left-right inclination of the counterweight 80. The counterweight 80 is reciprocated in the front-rear direction as the crankshaft 51 rotates counterclockwise together with the gear 50, and the sleeve 53 attached to the second eccentric shaft 51b moves within the elongated hole 80a.

[0055] When the second eccentric axis 51b is at the 0° position (the right end of the elongated hole 80a), the counterweight 80 is in a neutral state with no tilt in the left-right direction.

[0056] When the second eccentric shaft 51b rotates counterclockwise from the 0° position, passes through the 45° position, and reaches the 90° position (the center of the elongated hole 80a), the counterweight 80 is pushed by the counterclockwise rotating second eccentric shaft 51b and tilts slightly in the counterclockwise direction.

[0057] When the second eccentric shaft 51b rotates counterclockwise from the 90° position, passing through the 135° position and reaching the 180° position (the left end of the elongated hole 80a), the counterweight 80 returns to the neutral position.

[0058] When the second eccentric shaft 51b rotates counterclockwise from the 180° position, passes through the 225° position, and reaches the 270° position (center of the elongated hole 80a), the counterweight 80 is pushed by the counterclockwise rotating second eccentric shaft 51b and tilts slightly in the counterclockwise direction.

[0059] When the second eccentric axis 51b rotates counterclockwise from the 270° position, passing through the 315° position and reaching the 360° (0°) position, the counterweight 80 returns to the neutral position.

[0060] When the second eccentric axis 51b reaches the 90° and 270° positions, the counterweight 80 tends to tilt slightly in the counterclockwise direction. This is because it is subjected to a force in the front-to-back direction at a point offset from the center of the counterweight 80 in the left-to-right direction.

[0061] Conventionally, vibrations occurred when the force of the counterweight 80 attempting to tilt was transmitted to the gear case 60, or when the tilted counterweight 80 directly or indirectly contacted the gear case 60 in the left-right direction.

[0062] However, in this embodiment, the counterweight 80 is movable (tiltable) in the left-right direction, and dampers 83 are also arranged on both the left and right sides of the counterweight 80. Since vibrations are absorbed by the dampers 83, vibrations caused by the movement of the counterweight 80 are suppressed.

[0063] Figure 5 is a cross-sectional left side view showing the inclination of the counterweight 80 in the front-rear direction. During operation, the gear 50 receives a reaction force from the object and tilts slightly in the front-rear direction about the central axis 61b. When the gear 50 tilts, the counterweight 80, which is engaged with the crankshaft 51 and sleeve 53, also tilts slightly in the front-rear direction about the central axis 61b.

[0064] Figure 5(A) shows the normal state in which the counterweight 80 is not tilted in the front-to-back direction. In this state, the distance D between the lower surface of the lid 62 and the upper front end surface of the counterweight 80 is denoted as D0. Figure 5(B) shows the state in which the counterweight 80 is tilted forward. In this state, the distance D is D1. Figure 5(C) shows the state in which the counterweight 80 is tilted backward. In this state, the distance D is D2. The distance D is D1. <D0<D2である。

[0065] When the counterweight 80 tilts, the steel ball 81 positioned in the upper groove 80c also moves slightly in the vertical direction, and this movement generates vibration. However, in this embodiment, since the lid 62 is made of a thin metal plate and is flexible, the movement of the steel ball 81 in the vertical direction is absorbed by the bending of the lid 62, thereby suppressing vibration caused by the operation of the counterweight 80.

[0066] As explained above, the counterweight 80 is elastically supported by the damper 83 in the direction perpendicular to the front-rear direction, i.e., the left-right direction, and elastically supported by the lid 62 of the gear case 60 in the up-down direction. As a result, vibrations generated in the left-right direction by the movement of the counterweight 80 are absorbed by the damper 83. Furthermore, vibrations generated in the up-down direction are absorbed by the deflection of the lid 62. Therefore, the left-right and up-down movement (tilting) of the counterweight 80 is buffered, and vibrations and noise caused by this are suppressed.

[0067] Furthermore, during the reciprocating motion of the plunger 30, a large vibration occurs in the front-rear direction, but as a reaction to the movement, a rotational movement (up-down oscillation) occurs around a left-right axis (virtual axis) passing through the center of gravity G. In this embodiment, since the center of gravity G is located below the plunger 30 and the counterweight 80 is located above the plunger 30, the above-mentioned up-down oscillation can be effectively dampened even when a light counterweight is used. As a result, in addition to vibration reduction, the intermittent application of vertical loads to the support members (first roller 46 and second roller 47) supporting the plunger 30 can also be suppressed, thereby improving the lifespan of the support members. This invention relating to the positional relationship between the plunger 30 and the counterweight 80 with respect to the center of gravity is a separate invention from the elastic support mechanism of the counterweight 80.

[0068] [Modifications] The present invention is not limited to the embodiments described above, and can be modified in various ways without departing from its spirit.

[0069] In the above embodiment, an example was described in which the counterweight 80 is driven in the opposite phase to the plunger 30. However, the counterweight 80 may also operate with a phase difference of a few degrees from the opposite phase. That is, the counterweight 80 should be driven in a manner that cancels out vibrations caused by the reciprocating motion of the plunger 30.

[0070] In the above embodiment, an example was described in which the counterweight 80 is elastically supported by dampers 83 on both sides in the left-right direction. However, this elastic support may be on only the left or right side. Also, although the counterweight 80 is configured to be elastically supported by the dampers 83 via a weight guide 82, the weight guide 82 may be omitted, and the counterweight may be directly supported by an elastic body. For example, the weight guide 82 may be provided with a leaf spring-like portion that elastically deforms in the left-right direction, and the counterweight 80 may be directly supported by this leaf spring portion. In this case, frictional heat will be generated with the elastic body, raising concerns about reduced durability due to heat, but there is an advantage in that the number of parts can be reduced. Also, when the leaf spring-like portion is provided on the weight guide 82, it may be provided on either the inner surface or the outer surface, or both. When the leaf spring-like portion is provided on the outer surface, there is an advantage in that the elastically deformable portion and the counterweight 80 do not come into direct contact. Also, although the damper 83 is configured to be supported by the gear case 60 (transmission mechanism housing 61), it may be configured to be supported by the counterweight 80. In other words, the counterweight 80 and the elastic body may be configured to reciprocate as a single unit. For example, grooves may be provided in the left-right direction of the counterweight 80, and a linear elastic body may be embedded in these grooves, or O-rings (annular elastic bodies) may be fitted to the front, back, left, and right sides to absorb vibrations in the left-right direction. Alternatively, the counterweight itself may be configured to have an elastic portion. In other words, an elastically deformable portion may be provided within a single component called the counterweight.

[0071] In the above embodiment, an example was described in which the counterweight 80 is elastically supported in the vertical direction by the upper cover portion 62. However, this elastic support may also be provided directly or indirectly via a spring or the like by the lower transmission mechanism housing portion 61. Furthermore, this elastic support may be provided on both the upper and lower sides.

[0072] In the above embodiment, an example was described in which the damper 83 is made of rubber, but the damper 83 may be any elastic body containing rubber, urethane, sponge, or a spring. The spring may be a metal leaf spring, spring, disc spring, etc.

[0073] In the above embodiment, an example was described in which the rolling elements disposed inside the side grooves 80b and top grooves 80c of the counterweight 80 are steel balls 81 (spherical), but the rolling elements may also be, for example, rollers (columnar).

[0074] In the above embodiment, an example was described in which the counterweight 80 is driven by the operation of the crankshaft 51. However, the counterweight 80 may be driven by a configuration other than the crankshaft 51, for example, by attaching an eccentric pin directly to a gear that rotates about an axis in the vertical direction, and the elastic support mechanism can also be applied in that case. [Explanation of Symbols]

[0075] 10…Work implement, 20…Motor, 30…Plunger, 40…Holder, 46…First roller, 47…Second roller, 48…First shaft, 49…Second shaft, 50…Gear, 51…Crankshaft, 51a…First eccentric shaft, 51b…Second eccentric shaft, 51c…Connecting rod, 52…Needle bearing, 53…Sleeve, 60…Gear case, 61…Transmission mechanism housing, 62…Lid, 70…Connector, 70a…Slotted hole, 80…Counterweight, 80a…Slotted hole, 80b…Side groove, 80c…Top groove, 81…Steel ball, 82…Weight guide, 83…Damper

Claims

1. Motor and, A plunger to which a tool can be attached and which is reciprocated in the front-rear direction by the drive of the motor, A rotating body having an eccentric portion that rotates around a shaft extending vertically by the drive of the motor and revolves around the shaft, A counterweight is connected to the eccentric portion and reciprocates in the front-rear direction to cancel out vibrations caused by the reciprocating motion of the plunger, by transmitting a forward biasing force from the eccentric portion as it moves forward and a rearward biasing force from the eccentric portion as it moves rearward. A transmission mechanism comprising the eccentric portion and the rotating body, which transmits the rotational driving force of the motor to the plunger and the counterweight, A transmission mechanism case housing the aforementioned transmission mechanism, The system comprises an elastic body that elastically supports the counterweight in the left-right direction, The elastic body is supported by the counterweight or the transmission mechanism case. A work machine in which the elastic body dampens the lateral movement of the counterweight.

2. Motor and, A plunger to which a tool can be attached and which is reciprocated in the front-rear direction by the drive of the motor, A counterweight is driven by the motor to cancel out vibrations caused by the reciprocating motion of the plunger, A transmission mechanism that transmits the rotational driving force of the motor to the plunger and the counterweight, The transmission mechanism comprises the aforementioned transmission mechanism, an elastic body, a metal rolling element, and a transmission mechanism case that houses them. The elastic body is supported by the transmission mechanism case, the elastic body and the rolling element are arranged on at least one side of the counterweight in the left-right direction, and the rolling element is positioned between the elastic body and the counterweight in the left-right direction. A work machine in which the counterweight is supported so as to be able to reciprocate in the front-rear direction by the rolling element, which is elastically supported by the elastic body.

3. The work machine according to claim 2, wherein the counterweight is configured to reciprocate in the front-rear direction by a rotating body that rotates about an axis extending in the vertical direction by the drive of the motor.

4. The work machine according to claim 1 or 2, wherein the counterweight is elastically supported in the vertical direction.

5. The counterweight is provided with an elongated hole extending in the left-right direction. The work machine according to claim 1, wherein the counterweight receives power from the eccentric portion inserted through the elongated hole.

6. The work machine according to claim 1 or 2, wherein the center of gravity is located on the opposite side of the counterweight from the plunger.

7. The work machine according to claim 1, wherein the elastic body is arranged on at least one side of the counterweight in the left-right direction.

8. Having a metal rolling element, The transmission mechanism case houses the elastic body and the metal rolling element. The work machine according to claim 1, wherein the counterweight is supported so as to be reciprocable by the rolling element elastically supported by the elastic body.

9. The work machine according to claim 1 or 2, wherein the elastic body includes rubber, urethane, sponge, or a spring.

10. The transmission mechanism includes a gear that is rotationally driven by the motor around a shaft extending in the vertical direction, and a crankshaft that rotates together with the gear. One end of the crankshaft is eccentric from the shaft and connected to the plunger, The other end of the crankshaft is eccentric from the shaft and is engaged with the counterweight. The work machine according to claim 2, wherein the plunger and the counterweight are driven by the operation of the crankshaft.

11. The counterweight has a plurality of grooves, Rolling elements are arranged inside the groove. The transmission mechanism case has a flexible plate-shaped lid portion, The work machine according to claim 1, wherein the lid portion abuts against the rolling element.

12. The work machine according to claim 1, wherein the counterweight is rotatable about an axis in the vertical direction, and the elastic body undergoes elastic deformation by the rotation of the counterweight about the axis in the vertical direction.

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