JP2018044288A - Work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work machine that promotes damping of vibration of a vehicle body, when force is exerted to lift a portion of the vehicle body around a weight.SOLUTION: A hydraulic shovel includes an undercarriage, a revolving superstructure, a work attachment, a lower weight 151, an upper weight 152, a guide unit 153, a push-up spring 154, and a cushioning unit 155. The guide unit 153 guides the upper weight 152 movably in a vertical direction. The push-up spring 154 energizes the upper weight 152 upward. The cushioning unit 155 mitigates an impact from the upper weight 152 on the lower weight 151. When the upper weight 152 moves upward, the upper weight 152 separates upward from a piston head 155A of the cushioning unit 155.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a work machine provided with a counterweight.

  Conventionally, as a working machine such as a hydraulic excavator, a machine including a vehicle body, a work attachment, and a counterweight is known. The work attachment is disposed in the front part of the vehicle body and performs a predetermined excavation work. The counterweight is disposed in the rear part of the vehicle body and has a function of maintaining the balance of the vehicle body.

  Patent Document 1 discloses a technique in which a counterweight of a work machine is attached to a vehicle body via a vibration buffer. The vibration shock absorber includes a cylindrical return rubber portion that connects the counterweight and the vehicle body, a cylinder disposed inside the return rubber, and a piston that expands and contracts inside the cylinder. Furthermore, the cylinder is filled with a viscous material. The vibration buffer reduces vibrations of the counterweight during operation.

JP-A-8-284211

  In the technique described in Patent Document 1, the vibration buffer is always connected to the counterweight. For this reason, when a force that lifts the rear portion of the vehicle body is applied to the work machine, the counterweight and the vehicle body move up and down substantially together. In this case, there is a problem that the vibration of the work machine is difficult to attenuate.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a work machine that promotes damping of vehicle body vibration when a force that lifts upward is applied to the periphery of the weight of the vehicle body. And

  A work machine according to one aspect of the present invention is disposed above a vehicle body, a work attachment disposed on one end side of the vehicle body, and on the other end side opposite to the one end side of the vehicle body. A movable weight, a guide portion that guides the movable weight with respect to the vehicle body, a biasing unit that biases the movable weight upward, and a gap between the movable weight and the vehicle body. A unit that is disposed and is pressed by the movable weight when the movable weight moves downward, and the movable weight moves when the movable weight moves upward by a moving force including a biasing force of the biasing unit. In response to the pressed portion being in contact with the movable weight and the pressed portion being pressed by the movable weight. And a cushion that generates a resistance force that the resistance of downward movement of the movable weight, has a, a buffer unit to buffer the impact of the movable weight relative to the vehicle body.

  According to this configuration, the vertical movement of the movable weight with respect to the vehicle body is guided by the guide portion. The movable weight is biased upward by the biasing unit while moving up and down. As a result, when a force that lifts upward is applied to the periphery of the movable weight of the vehicle body, the movable weight can be moved away from the vehicle body. At this time, the movement is prevented from being hindered by the urging unit and the buffer unit. Therefore, it is possible to increase the stroke when the movable weight is lowered as compared with the case where the movable weight and the vehicle body move up and down integrally. For this reason, the energy when the movable weight is lowered is efficiently absorbed by the buffer unit. As a result, it is possible to promote the attenuation of the vibration of the vehicle body of the work machine.

  In the above configuration, the vehicle body has a fixed weight disposed below the movable weight, and the movable weight is guided by the guide portion so as to be vertically movable with respect to the fixed weight, It is desirable to constitute a counterweight that adjusts the balance of the vehicle body together with a fixed weight.

  According to this configuration, the position of the center of gravity of the work machine can be adjusted by the movable weight and the fixed weight disposed above and below. Then, the movable weight moves up and down with respect to the fixed weight, thereby facilitating damping of the vibration of the vehicle body of the work machine.

  In the above configuration, the movable weight is movable up and down between a lower limit position that is closest to the vehicle body and an upper limit position that is furthest upward from the vehicle body while being guided by the guide portion. It is desirable to apply an upward biasing force to the movable weight disposed at any position from the lower limit position to the upper limit position.

  According to this configuration, the movable weight is always urged upward. Therefore, when a force that lifts upward is applied to the periphery of the movable weight of the vehicle body, the separation operation of the movable weight with respect to the vehicle body is quickly started.

  In the above configuration, the biasing unit includes a spring member that is disposed between the movable weight and the vehicle body and generates an elastic force that biases the movable weight upward by being compressed. It is desirable that the free length of the spring member is set to be larger than the interval in the vertical direction between the movable weight disposed at the upper limit position and the vehicle body.

  According to this configuration, while the movable weight moves between the lower limit position and the upper limit position, it is possible to continue to generate a biasing force that pushes the movable weight upward.

  In the above-described configuration, a plurality of the guide portions are arranged at intervals in the horizontal direction, and the urging unit and the buffering unit are configured such that one of the plurality of guide portions and another guide portion are It is desirable to be arranged between them.

  According to this configuration, the movable weight can be stably pushed up between the plurality of guide portions, and the impact of the movable weight on the vehicle body can be stably buffered.

  ADVANTAGE OF THE INVENTION According to this invention, the working machine which accelerated | stimulated attenuation | damping of the vibration of the vehicle body when the force which lifts upwards with respect to the weight periphery of a vehicle body is provided.

1 is a side view of a work machine according to an embodiment of the present invention. It is a front view of the movable weight periphery of the working machine which concerns on one Embodiment of this invention. It is a schematic diagram which shows a mode that force which a movable weight lifts upwards with respect to the working machine which concerns on one Embodiment of this invention is provided. It is a mimetic diagram showing signs that a work machine concerning one embodiment of the present invention absorbs vibration. It is a mimetic diagram showing signs that a work machine concerning one embodiment of the present invention absorbs vibration. It is a mimetic diagram showing signs that a work machine concerning one embodiment of the present invention absorbs vibration. It is a front view of the movable weight periphery of the working machine which concerns on the deformation | transformation embodiment of this invention. It is a front view of the movable weight periphery of the working machine which concerns on the deformation | transformation embodiment of this invention. It is a front view of the movable weight periphery of the working machine which concerns on the deformation | transformation embodiment of this invention. It is a front view of the movable weight periphery of the working machine which concerns on the deformation | transformation embodiment of this invention. It is an enlarged plan view which shows the guide part of the working machine of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a hydraulic excavator 10 (work machine) according to an embodiment of the present invention. In the following, directions such as “up”, “down”, “left”, “right”, “front” and “rear” are shown in each figure. The structure of the hydraulic excavator 10 is shown for the sake of convenience, and the usage mode of the hydraulic excavator 10 is not limited.

  The hydraulic excavator 10 includes a lower traveling body 11 (vehicle body) and an upper revolving body 12 (vehicle body) supported on the lower traveling body 11 so as to be rotatable about a vertical axis. The lower traveling body 11 and the upper swing body 12 constitute a base of the excavator 10. The upper swing body 12 includes an upper frame 13 and a cab 14 and a counterweight 15 provided on the upper frame 13. The upper frame 13 is composed of a plate-like member that extends along the horizontal direction. The cab 14 is provided with an operation unit (not shown) operated by an operator of the excavator 10. The counterweight 15 is provided in the rear portion (the other end side) of the upper frame 13 and has a function of maintaining the balance of the excavator 10.

  Furthermore, a work attachment 16 is attached to the front portion (one end side) of the upper frame 13. The work attachment 16 is supported on the upper frame 13 by a support mechanism (not shown). The work attachment 16 includes a boom 17 that is mounted on the upper swing body 12 so as to be raised and lowered, an arm 18 that is rotatably connected to the tip of the boom 17, and a pivot that is pivotally connected to the tip of the arm 18. And a bucket 19.

  A boom cylinder 20 that is a boom hydraulic actuator, an arm cylinder 21 that is an arm hydraulic actuator, and a bucket cylinder 22 that is a bucket hydraulic actuator are mounted on the work attachment 16, and these cylinders can be extended and contracted. It is composed of a hydraulic cylinder. The boom cylinder 20 is interposed between the boom 17 and the upper swing body 12 so as to expand and contract by receiving the supply of hydraulic oil and rotate the boom 17 in the undulation direction. The arm cylinder 21 is interposed between the arm 18 and the boom 17 so as to expand and contract by receiving the supply of hydraulic oil and rotate the arm 18 around the horizontal axis with respect to the boom 17. Further, the bucket cylinder 22 is interposed between the bucket 19 and the arm 18 so as to expand and contract by receiving the supply of hydraulic oil and to rotate the bucket 19 around the horizontal axis with respect to the arm 18.

  The work machine to which the present invention is applied is not limited to the hydraulic excavator 10. The present invention can be widely applied to work machines including an object to be driven that is driven by hydraulic pressure or electric power.

  FIG. 2 is a front view of the periphery of the counterweight 15 (upper weight 152) of the excavator 10 according to the present embodiment. FIG. 2 corresponds to a view of the periphery of the counterweight 15 from the cab 14 side in FIG. The excavator 10 includes an upper weight 152 (movable weight), a pair of guide units 153 (guide portions), a push-up spring 154 (biasing unit), and a buffer unit 155. Further, the upper swing body 12 includes a lower weight 151 (fixed weight) disposed on the upper frame 13. In the present embodiment, the lower weight 151 and the upper weight 152 constitute a counterweight 15 that adjusts the balance (center of gravity position) of the excavator 10.

  The upper weight 152 is a weight portion having a rectangular parallelepiped shape that is disposed above the upper swing body 12 on the opposite side of the upper swing body 12 from the work attachment 16 (the rear portion of the excavator 10).

  The lower weight 151 is a weight portion having a rectangular parallelepiped shape fixed to the upper frame 13 of the upper swing body 12 below the upper weight 152. The lower weight 151 supports the guide unit 153, the push-up spring 154, and the buffer unit 155. In other words, in this embodiment, the counterweight portion that maintains the balance of the excavator 10 has a structure that is vertically divided into two. In another embodiment, the upper swing body 12 may not include the lower weight 151 and the upper frame 13 may support the guide unit 153, the push-up spring 154, and the buffer unit 155.

  The guide unit 153 guides the upper weight 152 to be movable up and down with respect to the lower weight 151 fixed to the upper frame 13. At this time, the upper weight 152 is between a first position (also referred to as a lower limit position) that is closest to the lower weight 151 in the vertical direction and a second position (also referred to as an upper limit position) that is above the first position. And be guided. As shown in FIG. 2, in this embodiment, a pair of guide units 153 are arranged in the left-right direction (horizontal direction), but in other embodiments, the guide units 153 are spaced in the front-rear direction. Alternatively, two pairs may be arranged. A plurality of guide units 153 may be arranged according to the weight of the upper weight 152.

  The guide unit 153 includes a guide cylinder 151A and a guide piston 152A. The guide cylinder 151A is a cylindrical member fixed to the lower weight 151. The upper end side of the guide cylinder 151A is opened, and a guide piston 152A is inserted into the opening. The guide piston 152A is a cylindrical member that is fixed to the upper weight 152 and protrudes downward. The pair of guide pistons 152 </ b> A reciprocate in the vertical direction inside the cylinder of the guide cylinder 151 </ b> A, whereby the vertical movement of the upper weight 152 is guided.

  The push-up spring 154 is a spring (spring member) disposed between the upper weight 152 and the lower weight 151 and between the pair of guide units 153. The lower end (one end) of the push-up spring 154 is fixed to the upper surface portion of the lower weight 151. The upper end (the other end) of the push-up spring 154 is fixed to the lower surface portion of the upper weight 152. The push-up spring 154 has a function of urging the upper weight 152 upward in the region from the first position to the second position. The push-up spring 154 generates an elastic force that urges the upper weight 152 upward by being compressed.

  The buffer unit 155 buffers the impact of the upper weight 152 on the lower weight 151 (upper swing body 12). The buffer unit 155 is disposed between the upper weight 152 and the lower weight 151 and between the pair of guide units 153. Specifically, the buffer unit 155 is fixed to the upper surface portion of the lower weight 151 so as to be adjacent to the push-up spring 154. In the present embodiment, the buffer unit 155 is a known rubber buffer. The buffer unit 155 is pressed downward by the upper weight 152 moving from the second position to the first position, thereby generating a resistance force that serves as a resistance to the movement of the upper weight 152 to the first position. To do. Further, the buffer unit 155 generates a resistance force that pulls the upper weight 152 downward when the upper weight 152 moves from the first position to the second position by the moving force including at least the urging force of the push-up spring 154. There is nothing to do.

  The buffer unit 155 includes a piston head 155A (a pressed portion), a cylindrical housing 155H, and a buffer rubber 155P (buffer body) disposed inside the housing 155H. The piston head 155A can reciprocate up and down with respect to the housing 155H. The piston head 155A is lowered by being pressed downward by the upper weight 152 that is lowered from the second position toward the first position. The piston head 155A has an upper weight so as to allow the upper weight 152 to move upward from the piston head 155A when the upper weight 152 moves upward by a moving force including the biasing force of the push-up spring 154. 152 abuts. The buffer rubber 155P is connected to the piston head 155A. The shock absorbing rubber 155P is compressed by the piston head 155A to generate a resistance force when the piston head 155A is pressed by the upper weight 152 and moves downward from a predetermined reference position. As a result, the buffer unit 155 buffers the impact of the upper weight 152 on the lower weight 151. In other embodiments, the buffer unit 155 is not limited to a rubber shock absorber, and may be a shock absorber, a damper, or the like having the above function.

  With reference to FIG. 2, in the present embodiment, when the excavator 10 is not being operated, the upper weight 152 has a predetermined weight depending on the balance between its own weight and the upward biasing force of the push-up spring 154. It is arranged at the standby position. At this time, a predetermined gap is formed in the vertical direction between the lower surface portion of the upper weight 152 and the piston head 155A. In the standby position, the push-up spring 154 is compressed from a predetermined free length.

  FIG. 3 is a schematic diagram showing a state in which a force that lifts the counterweight 15 (upper weight 152) upward is applied to the excavator 10 according to the present embodiment. 4A to 4C are schematic views showing a state in which the excavator 10 according to the present embodiment absorbs vibration. Referring to FIG. 3, when excavating the hydraulic excavator 10, if the tip of the bucket 19 comes into strong contact with the ground G, the counterweight 15 is lifted upward with respect to the counterweight 15 on the rear end side of the excavator 10. A force is applied (arrow D1 in FIGS. 3 and 4A). Along with this reaction force, the lower weight 151 fixed to the upper frame 13 is pushed upward. On the other hand, the timing at which this reaction force is transmitted to the upper weight 152 is shifted, and there is a time during which the upper weight 152 temporarily stops even after the reaction force is generated, so that the upper weight 152 relatively approaches the lower weight 151. (Arrow D2 in FIG. 4A). At this time, the push-up spring 154 is further compressed and deformed. Further, the lower surface portion of the upper weight 152 comes into contact with the piston head 155 </ b> A, and a resistance force that prevents the upper weight 152 from moving relative to the lower weight 151 is generated. As a result, the buffer unit 155 absorbs a part of the energy of the reaction force. Thereafter, the lower weight 151 and the upper weight 152 are pushed upward substantially integrally. As shown in FIG. 4A, the position at which the upper weight 152 is closest to the lower weight 151 in the vertical direction is defined as a first position (lower limit position) of the upper weight 152. The first position is a relative position of the upper weight 152 with respect to the lower weight 151.

  Referring to FIG. 4B, the lower weight 151 and the upper weight 152 are pushed upward and positioned at the uppermost position, and then the lower weight 151 starts to descend (arrow D3 in FIG. 4B). At this time, since the upper weight 152 is pushed upward by the push-up spring 154, the lowering timing of the upper weight 152 is delayed with respect to the lowering of the lower weight 151 (arrow D4 in FIG. 4B). As a result, as shown in FIG. 4B, the upper weight 152 is disposed at a second position spaced upward from the lower weight 151 relative to the first position in FIG. 4A. The second position is also a relative position of the upper weight 152 with respect to the lower weight 151, like the first position. In the present embodiment, the second position corresponds to a position (upper limit position) at which the upper weight 152 is spaced apart from the lower weight 151 (upper swing body 12) to the uppermost position.

  Thereafter, the upper weight 152 is lowered after the lower weight 151 that has been lowered first (arrow D5 in FIG. 4C). At this time, the downward energy of the upper weight 152 is efficiently absorbed by the compressive deformation of the push-up spring 154 and the buffer action by the buffer unit 155. Thereafter, the movement of the lower weight 151 and the upper weight 152 in FIGS. 4A to 4C is repeated while the amplitude of the vertical movement of the upper weight 152 with respect to the lower weight 151 is reduced.

  As described above, in the present embodiment, the vertical movement of the upper weight 152 relative to the upper swing body 12 (lower weight 151) is guided by the guide unit 153. Further, the upper weight 152 is urged upward by the push-up spring 154 at any position from the first position to the second position. Further, a predetermined interval is formed between the upper weight 152 disposed at the standby position and the second position and the piston head 155A of the buffer unit 155 (FIG. 4B). Therefore, when a force that lifts upward is applied to the periphery of the counterweight 15 of the excavator 10, the upper weight 152 can move away from the lower weight 151. At this time, the push-up spring 154 and the buffer unit 155 prevent the movement of the upper weight 152 from being hindered. In particular, the buffer unit 155 is prevented from pulling back the upper weight 152 that is being lifted. Further, the urging force of the push-up spring 154 can promote the upward movement of the upper weight 152. Therefore, the upper weight 152 is greatly separated upward from the lower weight 151, and the stroke with respect to the lower weight 151 when the upper weight 152 is lowered again can be increased. Therefore, the energy when the upper weight 152 is lowered is efficiently absorbed by the buffer unit 155. As a result, damping of the vibration of the vehicle body of the hydraulic excavator 10 is promoted.

  In other words, when the push-up spring 154 has an elastic force that pulls the upper weight 152 downward, or when the piston head 155A of the buffer unit 155 is always connected to the lower surface of the upper weight 152. The upper weight 152 cannot be freely separated from the lower weight 151. In this case, the upward movement (separation operation) of the upper weight 152 is limited, and the vibration of the excavator 10 is difficult to attenuate.

  In the present embodiment, the center of gravity of the excavator 10 can be adjusted by the upper weight 152 and the lower weight 151 that are arranged vertically. Then, the upper weight 152 moves up and down with respect to the lower weight 151, so that the vibration of the lower traveling body 11 and the upper swing body 12 is attenuated. Further, the weight having the same weight as the sum of the weights of the upper weight 152 and the lower weight 151 is smaller in weight than the case where the weight is reciprocated up and down like the upper weight 152, and the movable weight is energized. The urging force of the push-up spring 154 and the buffer performance of the buffer unit 155 can be set low.

  In the present embodiment, the push-up spring 154 includes a spring member having a lower end portion fixed to the lower weight 151 and an upper end portion fixed to the upper weight 152. The free length of the push-up spring 154 is set to be larger than the distance in the vertical direction between the upper weight 152 and the lower weight 151 arranged at the second position. In other words, while the lower weight 151 moves up and down, the push-up spring 154 is not always extended and is in a compressed state. Therefore, while the upper weight 152 moves between the first position and the second position, it is possible to generate a biasing force that the push-up spring 154 always pushes the upper weight 152 upward. As a result, the stroke when the upper weight 152 is lowered is set large.

  In the present embodiment, as shown in FIG. 2, in the static standby state of the excavator 10, the upper weight 152 is formed so that a gap is formed between the lower surface portion of the upper weight 152 and the piston head 155A. And the urging force of the push-up spring 154 are preset. For this reason, even when a large reaction force is suddenly applied to the rear end side of the excavator 10, the reaction force can be quickly absorbed and buffered.

  In the present embodiment, the push-up spring 154 and the buffer unit 155 are disposed between the plurality of guide units 153. Therefore, the upper weight 152 can be pushed up stably, and the impact of the upper weight 152 on the lower weight 151 can be buffered stably.

  The hydraulic excavator 10 (work machine) according to the embodiment of the present invention has been described above. The present invention is not limited to these forms. The following modified embodiments are possible as the working machine according to the present invention.

  (1) In the above-described embodiment, as illustrated in FIG. 2, in the static standby state of the excavator 10, the lower surface portion of the upper weight 152 and the piston head 155 </ b> A are not in contact with each other. However, the present invention is not limited to this. In the standby state of the excavator 10, the lower surface portion of the upper weight 152 may be in contact with the piston head 155A. Even in this case, the counterweight 15 of the excavator 10 is applied with a reaction force in the direction of the arrow DA in FIG. 3, and when the upper weight 152 is separated from the lower weight 151, the lower surface portion of the upper weight 152 is separated from the piston head 155A. do it. In addition, the upper limit position (second position) of the upper weight 152 guided by the guide unit 153 changes depending on the magnitude of the impact and external force applied to the excavator 10. Therefore, it is desirable that the upper weight 152 is guided so as to be movable up and down so that the upper weight 152 can be separated to a predetermined height with a margin with respect to the lower weight 151. Further, the free length of the push-up spring 154 may be set so that the urging force of the push-up spring 154 against the upper weight 152 becomes zero when the upper weight 152 is disposed at the second position. Further, the upper end portion of the push-up spring 154 may be separated from the lower surface portion of the upper weight 152 before the upper weight 152 reaches the second position. A spring member instead of the push-up spring 154 may be connected to the upper surface portion of the upper weight 152. In this case, the spring member is extended from a predetermined free length, thereby generating an urging force that pulls the upper weight 152 upward by the pulling force.

  (2) Moreover, in said embodiment, although demonstrated using the hydraulic shovel 10 as a working machine which concerns on this invention, this invention is not limited to this. The work machine according to the present invention may be a crane, a dismantling machine, an excavator, a handling machine, or the like. Further, the work machine may be composed of a single vehicle body, such as the hydraulic excavator 10, without including the vehicle bodies separated above and below the lower traveling body 11 and the upper swing body 12.

  (3) In the above embodiment, the push-up spring 154 included in the excavator 10 is described as the urging unit according to the present invention. However, the present invention is not limited to this. FIG. 5 is a front view of the periphery of a counterweight 15M provided in a hydraulic excavator (work machine) according to a modified embodiment of the present invention. In this modified embodiment, the work machine is different from the previous embodiment in that the working machine includes a hydraulic cylinder 161, a pressure oil supply unit 162A, a relief valve 162B, and an oil discharge tank 162C. The description of common points is omitted. The hydraulic cylinder 161 is disposed between the upper weight 152 and the lower weight 151, and urges the upper weight 152 upward in a region from the first position to the second position. The hydraulic cylinder 161 is connected to the upper weight 152 and urges the upper weight 152 upward by the pressure of pressure oil (working fluid). The pressure oil supply unit 162 </ b> A supplies pressure oil to the hydraulic cylinder 161. Note that the pressure oil supply unit 162A includes a pressure reducing valve (not shown) inside, and adjusts the pressure of the pressure oil supplied to the hydraulic cylinder 161 to be constant. The relief valve 162B is opened when the upper weight 152 is lowered and the pressure in the hydraulic cylinder 161 is increased. Then, the pressure oil discharged from the hydraulic cylinder 161 is discharged to the oil discharge tank 162C. As a result, when the upper weight 152 moves up and down, the pressure of the pressure oil in the hydraulic cylinder 161 is kept constant.

  Even with such a configuration, it is possible to generate an urging force that always pushes the upper weight 152 upward while the upper weight 152 is lifted from the first position to the second position. For this reason, the stroke when the upper weight 152 descends becomes large, and vibration based on the reaction force applied to the periphery of the counterweight 15M can be attenuated at an early stage. In another modified embodiment, a predetermined gas spring may push up the upper weight 152 in place of the hydraulic cylinder 161. Also in this case, it is desirable that a member corresponding to the pressure oil supply unit 162 adjusts the gas pressure in the gas spring to be constant. Further, the pressure of the working fluid may be adjusted to be constant by a hydraulic circuit including an air compressor or a hydraulic pump instead of the pressure oil supply unit 162.

  (4) Furthermore, in the above-described embodiment, the guide unit 153 (FIG. 2) included in the excavator 10 is described as the guide portion according to the present invention, but the present invention is not limited to this. FIG. 6 is a front view of the periphery of a counterweight 15N provided in a hydraulic excavator (work machine) according to a modified embodiment of the present invention. In this modified embodiment, the work machine is different from the previous embodiment in that the work machine includes a guide link 163 (guide portion). Therefore, the difference will be mainly described and description of common points will be omitted. . In the present embodiment, the guide link 163 guides the upper weight 152 so as to be vertically movable between the first position and the second position. The guide link 163 includes an upper link 163A and a lower link 163B. An upper end portion of the upper link 163A is rotatably supported by the upper weight 152, and a lower end portion of the lower link 163B is rotatably supported by the lower weight 151. Further, the lower end portion of the upper link 163A and the upper end portion of the lower link 163B are connected to each other so as to be rotatable. The vertical movement of the upper weight 152 is also stably guided by the guide link 163 having such a link structure.

  FIG. 7 is a front view of the periphery of a counterweight 15P provided in a hydraulic excavator (work machine) according to a modified embodiment of the present invention. In this modified embodiment, the work machine is different from the previous embodiment in that the work machine includes a guide slider 164 (guide portion). Therefore, the difference will be mainly described and description of common points will be omitted. . In the present embodiment, the guide slider 164 guides the upper weight 152 so as to be vertically movable between the first position and the second position. The guide slider 164 includes a slider hole 164A and a rubber support 164B. The slider hole portion 164 </ b> A is a cylindrical space portion that is opened so as to penetrate the upper weight 152. The rubber column 164 </ b> B is a rubber column member protruding upward from the upper surface of the lower weight 151. The rubber column 164B is inserted into the slider hole 164A. The vertical movement of the upper weight 152 is also stably guided by the guide slider 164 having such a cylinder structure.

  FIG. 8 is a front view of the periphery of the counterweight 15Q provided in the hydraulic excavator (work machine) according to a modified embodiment of the present invention. In this modified embodiment, the work machine is different from the previous embodiment in that the work machine includes a side guide 165 (guide portion). Therefore, the difference will be mainly described and description of common points will be omitted. . FIG. 9 is an enlarged plan view showing a part of the side guide 165. In the present embodiment, the side guide 165 guides the upper weight 152 so as to be vertically movable between the first position and the second position. The side guide 165 includes a protrusion 165A and a guide rail 165B. The protrusions 165A are formed at both ends of the upper weight 152 in the left-right direction. The protrusion 165A is a hexagonal protrusion in a top view and extends long in the vertical direction. On the other hand, the guide rail 165B is a substantially U-shaped frame body as viewed from above, which is disposed so as to protrude upward from the upper surface portion of the lower weight 151. As shown in FIG. 9, the protrusion 165A is fitted inside the guide rail 165B. The vertical movement of the upper weight 152 is also stably guided by the side guide 165 having such a rail structure. The protrusion 165A may be made of a material such as cast iron or brass, and grease (lubricant) may be applied to the sliding portion between the protrusion 165A and the guide rail 165B. Furthermore, the sliding part may be composed of an oilless bearing structure.

  (5) In the above embodiment, the counter weight 15 is integrally disposed on the rear side of the upper swing body 12. However, the present invention is not limited to this. A plurality of counterweights 15 shown in FIG. 2 may be arranged adjacent to each other in the front-rear direction. In this case, referring to FIG. 3, in order to suitably absorb the reaction force (arrow D1) applied to the rear side of the excavator 10, a plurality of counterweights 15 that are far from the bucket 19 and that In the counterweight 15 located on the rear side of the frame 13, it is desirable that the vertical movement amount of the upper weight 152, the urging force (pushing force) by the push-up spring 154, and the buffering performance by the buffer unit 155 are set to be larger.

10 Hydraulic excavator 11 Lower traveling body (vehicle body)
12 Upper swing body (car body)
13 Upper frame 14 cab 15, 15M, 15N, 15P, 15Q Counterweight 151 Lower weight (fixed weight)
151A Guide cylinder 152 Upper weight (movable weight)
152A Guide piston 153 Guide unit (guide part)
154 Push-up spring (biasing unit, spring member)
155 Buffer unit 155A Piston head (pressed part)
155P Buffer rubber (buffer)
16 Work Attachment 161 Hydraulic Cylinder 162 Pressure Oil Supply Unit 163 Guide Link (Guide Unit)
163A Upper link 163B Lower link 164 Guide slider (guide part)
164A Slider hole 164B Rubber strut 165 Side guide (guide part)
165A Projection 165B Guide rail 17 Boom 18 Arm 19 Bucket 20 Boom cylinder 21 Arm cylinder 22 Bucket cylinder

Claims (5)

The car body,
A work attachment disposed on one end of the vehicle body;
A movable weight disposed above the vehicle body on the other end side opposite to the one end side of the vehicle body;
A guide portion that guides the movable weight so as to be vertically movable with respect to the vehicle body;
A biasing unit that biases the movable weight upward;
A unit disposed between the movable weight and the vehicle body,
When the movable weight moves downward, the movable weight is pressed by the movable weight, and when the movable weight moves upward by the moving force including the urging force of the urging unit, the movable weight is allowed to be separated upward. A pressed portion that comes into contact with the movable weight;
In response to the pressed portion being pressed by the movable weight, a buffer that generates a resistance force that is a resistance to the downward movement of the movable weight;
A buffer unit for buffering the impact of the movable weight on the vehicle body,
Having working machine. The vehicle body has a fixed weight disposed below the movable weight,
The work machine according to claim 1, wherein the movable weight is guided by the guide portion so as to be movable up and down with respect to the fixed weight, and constitutes a counterweight that adjusts a balance of the vehicle body together with the fixed weight. The movable weight is movable up and down between a lower limit position closest to the vehicle body and an upper limit position farthest away from the vehicle body while being guided by the guide portion,
The work machine according to claim 1 or 2, wherein the biasing unit applies a biasing force directed upward to the movable weight disposed at any position from the lower limit position to the upper limit position. The biasing unit includes a spring member that is disposed between the movable weight and the vehicle body and generates an elastic force that biases the movable weight upward by being compressed,
4. The work machine according to claim 3, wherein a free length of the spring member is set to be larger than a distance in a vertical direction between the movable weight disposed at the upper limit position and the vehicle body. 5. A plurality of the guide portions are arranged at intervals in the horizontal direction,
5. The work machine according to claim 1, wherein the biasing unit and the buffer unit are disposed between one guide portion and the other guide portion of the plurality of guide portions. .

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