Work device for construction machine

Abstract

To enhance workability when stopping the coming-off of a left connection pin and a right connection pin connecting between a first member and a second member.SOLUTION: A connection device 15 for connecting between a lower boom 5A and an intermediate boom 5B includes a pin coming-off stopping mechanism 24 for limiting a connection part 16C between a left second link 21 and a right second link 22 and a hydraulic cylinder 16 moving in the direction approaching a pin axis A-A, in a front connection state.At the left second bracket 11 and the right second bracket 12, a connection pin contact member 29 is provided for limiting the movement by coming into contact with a left upper connection pin 13U and a right upper connection pin 14U when the connection part 16C between the left second link 21 and the right second link 22 and the hydraulic cylinder 16 moving in the direction away from the pin axis A-A, in a front connection state.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a work device provided on a construction machine such as a hydraulic excavator. [Background technology]

[0002] A hydraulic excavator, a typical example of construction machinery, is composed of a self-propelled vehicle body and a working device rotatably attached to the vehicle body. Hydraulic excavators equipped with a working device for demolition work are preferably used when demolishing structures that are high above ground, such as high-rise buildings. This working device for demolition work typically has multiple booms called multi-booms, with an arm attached to the tip of the uppermost boom of each boom, and a working tool such as a crusher or grapple attached to the tip of the arm.

[0003] A multi-boom for demolition work is configured to a desired length by connecting multiple booms together. These multiple booms are detachably connected using connecting pins. That is, of the two connected booms, a left first member and a right first member are provided facing each other in the left-right direction on one boom, and a left second member and a right second member are provided facing each other in the left-right direction on the other boom, and are connected by a left connecting pin and a right connecting pin, respectively.

[0004] A working apparatus has been proposed that includes a coupling device that inserts and removes a left connecting pin between a left first member provided on one boom and a left second member provided on the other boom, and inserts and removes a right connecting pin between a right first member provided on one boom and a right second member provided on the other boom. This coupling device includes a hydraulic cylinder, a floating link attached to the hydraulic cylinder, a left first link having one end connected to the left connecting pin and the other end connected to the floating link, a right first link having one end connected to the right connecting pin and the other end connected to the floating link, a left second link having one end connected to an intermediate portion of the left first link and the other end connected to a hydraulic cylinder, and a right second link having one end connected to an intermediate portion of the right first link and the other end connected to the hydraulic cylinder together with the other end of the left second link.

[0005] In the connecting device, when the hydraulic cylinder performs an extension / contraction operation, one end of the left first link and one end of the right first link move left and right around the connection point with the floating link as a fulcrum, whereby the left connecting pin and the right connecting pin are inserted into and removed from the pin insertion holes of the left first member and the right first member provided on one boom and the pin insertion holes of the left second member and the right second member provided on the other boom (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5139385 Summary of the Invention [Problem to be solved by the invention]

[0007] In the connecting device of Patent Document 1, a left connecting pin is inserted through the pin insertion hole of the left first member and the pin insertion hole of the left second member, and a state in which a right connecting pin is inserted through the pin insertion hole of the right first member and the pin insertion hole of the right second member is maintained by a hydraulic cylinder.

[0008] Here, an appropriate gap is formed between the left first member and the left second member, which are connected via the left connecting pin, and between the right first member and the right second member, which are connected via the right connecting pin. Therefore, the left connecting pin and the right connecting pin move little by little in the axial direction due to vibrations when the hydraulic excavator is performing demolition work, etc. As a result, a force acts on the left connecting pin in a direction that causes it to disengage from the pin insertion holes of the left first member and the left second member, and a force acts on the right connecting pin in a direction that causes it to disengage from the pin insertion holes of the right first member and the right second member. For this reason, it is necessary to prevent the left connecting pin and the right connecting pin from coming out of the first member or the second member using a bolt or the like.

[0009] However, the work of retaining the left and right connecting pins with bolts or the like is performed manually, which reduces workability. Furthermore, if the left and right connecting pins are located high above the ground, the work of retaining the left and right connecting pins with bolts or the like becomes high-altitude work, which further reduces workability.

[0010] An object of the present invention is to provide a working device for a construction machine that improves workability when retaining the left connecting pin and right connecting pin that connect the first member and the second member. [Means for solving the problem]

[0011] The present invention provides a first front member having a left first member with a left first pin insertion hole formed therein and a right first member with a right first pin insertion hole formed therein, a second front member having a left second member with a left second pin insertion hole formed therein and a right second member with a right second pin insertion hole formed therein, and a coupling device that couples the first front member and the second front member, the coupling device including a left connecting pin that is inserted into the left first pin insertion hole and the left second pin insertion hole, a right connecting pin that is inserted into the right first pin insertion hole and the right second pin insertion hole, and a coupling device that couples the left connecting pin and the a hydraulic cylinder disposed at a position spaced apart from the pin axis of the right connecting pin; a floating link attached to either the tube or the rod of the hydraulic cylinder and disposed in a floating state so as to be movable in a direction toward or away from the pin axis; a left first link having one end connected to the left connecting pin and the other end connected to the floating link; a right first link having one end connected to the right connecting pin and the other end connected to the floating link; and one end connected to an intermediate portion of the left first link and the other end connected to the other of the tube or the rod of the hydraulic cylinder. In a working device for a construction machine including a left second link and a right second link having one end connected to an intermediate portion of the right first link and the other end connected to the other of the tube or rod of the hydraulic cylinder, in a front connected state in which the first front member and the second front member are connected by the connecting device, the connecting portions of the left second link and the right second link and the hydraulic cylinder are located closer to the pin axis than the connecting portion of the left second link and the left first link and the connecting portion of the right second link and the right first link. The connecting device is provided with a pin prevention mechanism that restricts movement of the connecting portions between the left second link and the right second link and the hydraulic cylinder in a direction approaching the pin axis in the front connected state, and the left second member and the right second member are provided with connecting pin abutment members that abut against the left connecting pin and the right connecting pin to restrict movement when the connecting portions between the left second link and the right second link and the hydraulic cylinder in a direction away from the pin axis in the front connected state. [Effects of the Invention]

[0012] According to the present invention, the pin retention mechanism and the connecting pin abutment member can prevent the left connecting pin from falling out while inserted into the left first pin insertion hole and the left second pin insertion hole, and can prevent the right connecting pin from falling out while inserted into the right first pin insertion hole and the right second pin insertion hole. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a left side view showing a hydraulic excavator equipped with a multi-boom type working implement. [Figure 2] FIG. 2 is a left side view showing a front connected state in which the lower boom and intermediate boom of the working device are connected to each other. [Figure 3] FIG. 2 is a perspective view showing the lower boom, the intermediate boom, the upper left connecting pin, the connecting pin abutment member, etc. [Figure 4] 4 is a cross-sectional view of the connecting device and the connecting pin abutment member according to the first embodiment, as viewed in the direction of arrows IV-IV in FIG. 2. FIG. [Figure 5] 5 is a cross-sectional view of the upper left connecting pin, the connecting pin abutment member, etc., as viewed from the direction of arrows VV in FIG. 4. [Figure 6] 5 is a cross-sectional view taken from a position similar to that of FIG. 4, illustrating a state in which the upper left connecting pin and the upper right connecting pin have been inserted into the left inner first bracket and the right inner first bracket. FIG. [Figure 7] 5 is a cross-sectional view taken from a position similar to that of FIG. 4, illustrating a state in which the upper left connecting pin and the upper right connecting pin are inserted into the second left bracket and the second right bracket. FIG. [Figure 8] 5 is a cross-sectional view taken from the same position as FIG. 4, illustrating a state in which the columnar projections of the upper left connecting pin and the upper right connecting pin are inserted into the through-holes of the connecting pin abutment member. [Figure 9] 5 is a cross-sectional view taken from a position similar to that of FIG. 4, showing the state in which the left first bracket and the left second bracket are connected via the left upper connecting pin, and the right first bracket and the right second bracket are connected via the right upper connecting pin. [Figure 10]5 is a cross-sectional view taken from the same position as FIG. 4, illustrating a state in which the cylindrical projections of the upper left connecting pin and the upper right connecting pin are in contact with connecting pin contact members in the front connected state. [Figure 11] FIG. 10 is a work flow diagram showing a state in which a hydraulic excavator with a lower boom attached is brought close to an intermediate boom placed on the ground during front coupling work. [Figure 12] FIG. 10 is a work process diagram showing the state in which the lower boom and the intermediate boom are connected via the upper left connecting pin and the upper right connecting pin in the front connecting work. [Figure 13] 10 is a process diagram showing the state in which pin insertion holes through which the lower left connecting pin and the lower right connecting pin are inserted are aligned in the front connecting work. FIG. [Figure 14] FIG. 10 is a cross-sectional view showing a connecting device provided with a pin removal prevention mechanism according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of a working device for a construction machine according to the present invention will be described in detail below with reference to the accompanying drawings, taking as an example a multi-boom working device mounted on a hydraulic excavator. In this embodiment, the traveling direction of the hydraulic excavator is defined as the front-rear direction, and the direction perpendicular to the traveling direction of the hydraulic excavator is defined as the left-right direction.

[0015] 1 to 13 show a first embodiment of the present invention. In the drawings, a hydraulic excavator 1 comprises a self-propelled crawler-type lower traveling body 2 and an upper rotating body 3 rotatably mounted on the lower traveling body 2. The lower traveling body 2 and the upper rotating body 3 form the vehicle body of the hydraulic excavator 1, and a cab 3A is disposed on the front left side of the upper rotating body 3. A multi-boom type working device 4 is rotatably attached to the front side of the upper rotating body 3. The hydraulic excavator 1 is suitably used for demolition work in which the working device 4 is used to demolish structures that are high above the ground.

[0016] The multi-boom working device 4 has a boom 5 consisting of a lower boom 5A, an intermediate boom 5B, and an upper boom 5C that are rotatably attached to the front side of the upper rotating body 3. The lower boom 5A forms a first front member, and is provided with a left first bracket 9 and a right first bracket 10, which will be described later. The intermediate boom 5B forms a second front member, and is provided with a left second bracket 11 and a right second bracket 12, which will be described later. A middle arm 6 is rotatably attached to the tip of the upper boom 5C. An arm 7 is rotatably attached to the tip of the middle arm 6, and a crusher 8, serving as a working tool, is rotatably attached to the tip of the arm 7.

[0017] The vehicle body of the hydraulic excavator 1 and the working implement 4 are usually loaded onto separate transport vehicles and transported to the work site. Then, as shown in FIGS. 11 to 13 , an operation is performed to connect the lower boom 5A attached to the hydraulic excavator 1 (upper rotating body 3) to the intermediate boom 5B of the working implement 4, which is placed on the ground using a dedicated support 100. By this connection operation, as shown in FIG. 4 , the left first bracket 9 attached to the tip of the lower boom 5A and the left second bracket 11 attached to the base end of the intermediate boom 5B are connected via the left connecting pin 13 (upper left connecting pin 13U and lower left connecting pin 13L), and the right first bracket 10 attached to the tip of the lower boom 5A and the right second bracket 12 attached to the base end of the intermediate boom 5B are connected via the right connecting pin 14 (upper right connecting pin 14U and lower right connecting pin 14L).

[0018] The left first bracket 9 serving as the left first member is fixed to the left side of the tip of the lower boom 5A by means of welding or the like. The left first bracket 9 has a left inner first bracket 9A and a left outer first bracket 9B that face each other in the left-right direction with a certain distance between them. The left inner first bracket 9A and left outer first bracket 9B connect the lower boom 5A and the intermediate boom 5B, and therefore extend in the vertical direction when the lower boom 5A is in the connected position (the position shown in FIG. 2) in which it is extended forward.

[0019] A left second bracket 11, which will be described later, is disposed between the left inner first bracket 9A and the left outer first bracket 9B. Left first pin insertion holes 9C penetrating in the left-right direction are bored in both up-down ends of the left inner first bracket 9A and the left outer first bracket 9B when the lower boom 5A is in the coupled position. An upper-left connecting pin 13U is removably inserted through the two left first pin insertion holes 9C located at the upper ends of the left inner first bracket 9A and the left outer first bracket 9B. A lower-left connecting pin 13L is removably inserted through the two left first pin insertion holes 9C located at the lower ends of the left inner first bracket 9A and the left outer first bracket 9B.

[0020] The right first bracket 10, which serves as the right first member, is fixed to the right side of the tip of the lower boom 5A by means of welding or the like. The right first bracket 10 is bifurcated and consists of a right inner first bracket 10A and a right outer first bracket 10B that face each other in the left-right direction with a certain distance between them. The right inner first bracket 10A and the right outer first bracket 10B extend in the vertical direction when the lower boom 5A is in the coupled position.

[0021] A right second bracket 12, which will be described later, is disposed between the right inner first bracket 10A and the right outer first bracket 10B. Right first pin insertion holes 10C penetrating in the left-right direction are formed at both ends of the right inner first bracket 10A and the right outer first bracket 10B in the up-down direction when the lower boom 5A is in the coupled position. An upper right connecting pin 14U is removably inserted through two right first pin insertion holes 10C located at the upper ends of the right inner first bracket 10A and the right outer first bracket 10B. A lower right connecting pin 14L is removably inserted through two right first pin insertion holes 10C located at the lower ends of the right inner first bracket 10A and the right outer first bracket 10B.

[0022] The left first pin insertion hole 9C drilled in the left inner first bracket 9A and the left outer first bracket 9B of the left first bracket 9, and the right first pin insertion hole 10C drilled in the right inner first bracket 10A and the right outer first bracket 10B of the right first bracket 10 are positioned on the pin axis AA of the left connecting pin 13 and the right connecting pin 14 described later.

[0023] The left second bracket 11, which serves as the left second member, is fixed to the left side of the base end of the intermediate boom 5B by means of welding or the like. The left second bracket 11 is disposed between the left inner first bracket 9A and the left outer first bracket 9B of the left first bracket 9, and faces the left inner first bracket 9A and the left outer first bracket 9B in the left-right direction. A left second pin insertion hole 11A penetrating in the left-right direction is drilled in the left second bracket 11 at a position corresponding to the left first pin insertion hole 9C of the left first bracket 9.

[0024] The right second bracket 12, which serves as the right second member, is fixed to the right side of the base end of the intermediate boom 5B by means of welding or the like. The right second bracket 12 is disposed between the right inner first bracket 10A and the right outer first bracket 10B of the right first bracket 10, and faces these right inner first bracket 10A and right outer first bracket 10B in the left-right direction. A right second pin insertion hole 12A penetrating in the left-right direction is drilled in the right second bracket 12 at a position corresponding to the right first pin insertion hole 10C of the right first bracket 10.

[0025] The left second pin insertion hole 11A of the left second bracket 11 overlaps on the same pin axis AA as the left first pin insertion hole 9C of the left first bracket 9, and the right second pin insertion hole 12A of the right second bracket 12 overlaps on the same pin axis AA as the right first pin insertion hole 10C of the right first bracket 10.

[0026] The left connecting pin 13 connects the first left bracket 9 and the second left bracket 11. The left connecting pin 13 has an upper left connecting pin 13U and a lower left connecting pin 13L that form a pair in the vertical direction when connecting the lower boom 5A and the intermediate boom 5B. The upper left connecting pin 13U is removably inserted into a first left pin insertion hole 9C located at the upper end of the first left bracket 9 and a second left pin insertion hole 11A located at the upper end of the second left bracket 11. The lower left connecting pin 13L is removably inserted into a first left pin insertion hole 9C located at the lower end of the first left bracket 9 and a second left pin insertion hole 11A located at the lower end of the second left bracket 11. A cylindrical protrusion 30, which will be described later, is provided on an end face 13U1 on one axial side of the upper left connecting pin 13U.

[0027] The right connecting pin 14 connects the right first bracket 10 and the right second bracket 12. The right connecting pin 14 has an upper right connecting pin 14U and a lower right connecting pin 14L that form a pair in the vertical direction when connecting the lower boom 5A and the intermediate boom 5B. The upper right connecting pin 14U is removably inserted into a right first pin insertion hole 10C located at the upper end of the right first bracket 10 and a right second pin insertion hole 12A located at the upper end of the right second bracket 12. The lower right connecting pin 14L is removably inserted into a right first pin insertion hole 10C located at the lower end of the right first bracket 10 and a right second pin insertion hole 12A located at the lower end of the right second bracket 12. The upper right connecting pin 14U and the upper left connecting pin 13U are arranged on the same pin axis AA, and the lower right connecting pin 14L and the lower left connecting pin 13L are arranged on the same pin axis AA. A cylindrical projection 30, which will be described later, is provided on one axial end face 14U1 of the upper right connecting pin 14U.

[0028] In this way, the upper left connecting pin 13U and the lower left connecting pin 13L are respectively inserted into the left first pin insertion hole 9C of the left first bracket 9 and the left second pin insertion hole 11A of the left second bracket 11. The upper right connecting pin 14U and the lower right connecting pin 14L are respectively inserted into the right first pin insertion hole 10C of the right first bracket 10 and the right second pin insertion hole 12A of the right second bracket 12. As a result, the left first bracket 9 and the left second bracket 11 are connected via the upper left connecting pin 13U and the lower left connecting pin 13L, and the right first bracket 10 and the right second bracket 12 are connected via the upper right connecting pin 14U and the lower right connecting pin 14L, thereby connecting the lower boom 5A and the intermediate boom 5B.

[0029] Next, we will explain the connecting device 15 arranged between the left first bracket 9 and the right first bracket 10. The connecting device 15 inserts and removes the upper-left connecting pin 13U and the lower-left connecting pin 13L into the left first pin insertion hole 9C and the left second pin insertion hole 11A, and inserts and removes the upper-right connecting pin 14U and the lower-right connecting pin 14L into the right first pin insertion hole 10C and the right second pin insertion hole 12A.

[0030] Two coupling devices 15 are provided: one between the upper-left connecting pin 13U and the upper-right connecting pin 14U, and one between the lower-left connecting pin 13L and the lower-right connecting pin 14L. Because these two coupling devices 15 have the same configuration, the following describes the coupling device 15 located between the upper-left connecting pin 13U and the upper-right connecting pin 14U. The coupling device 15 includes the upper-left connecting pin 13U, the upper-right connecting pin 14U, a hydraulic cylinder 16 (described below), a floating link 17, a first left link 19, a first right link 20, a second left link 21, a second right link 22, and a pin retention mechanism 24. Similarly to the above, the coupling device 15 located between the lower-left connecting pin 13L and the lower-right connecting pin 14L also includes the hydraulic cylinder 16, the floating link 17, the first left link 19, the first right link 20, the second left link 21, the second right link 22, and a pin retention mechanism 24.

[0031] The hydraulic cylinder 16 is disposed at a position spaced apart from the pin axis AA of the upper left connecting pin 13U and the upper right connecting pin 14U. The hydraulic cylinder 16 is composed of a tube 16A, a piston (not shown), and a rod 16B whose base end is fixed to the piston and whose tip end protrudes from the tube 16A. The hydraulic cylinder 16 extends and retracts the rod 16B by supplying and discharging pressure oil from a hydraulic source.

[0032] The floating link 17 is attached to the hydraulic cylinder 16. The floating link 17 is formed of two triangular plates that face each other with the tube 16A of the hydraulic cylinder 16 in between, and is attached to the tube 16A. The floating link 17 is not attached to either the left first bracket 9 or the right first bracket 10, and is disposed in a floating state so that it can move toward or away from the pin axis AA of the upper-left connecting pin 13U and the upper-right connecting pin 14U.

[0033] The length of the floating link 17 in the left-right direction is set to be smaller than the distance between the left inner first bracket 9A and the right inner first bracket 10A. As a result, a gap is formed between the left end of the floating link 17 and the left inner first bracket 9A, and between the right end of the floating link 17 and the right inner first bracket 10A. Therefore, the floating link 17 can move between the left inner first bracket 9A and the right inner first bracket 10A in response to the extension and contraction of the hydraulic cylinder 16. The bottom side of the hydraulic cylinder 16 (tube 16A) is rotatably attached to a middle portion of the floating link 17 in the left-right direction via a pin 18. In addition, the base ends of a left first link 19 and a right first link 20, which will be described later, are each rotatably connected to the floating link 17.

[0034] The left first link 19 connects the upper left connecting pin 13U and the floating link 17. The left first link 19 is formed of two plates facing each other with the floating link 17 in between. One end 19A of the left first link 19 is connected to the upper left connecting pin 13U via pin 19B. The other end 19C of the left first link 19 is connected to the floating link 17 via pin 19D.

[0035] The right first link 20 connects the upper right connecting pin 14U and the floating link 17. The right first link 20 is formed of two plates facing each other with the floating link 17 in between. One end 20A of the right first link 20 is connected to the upper right connecting pin 14U via pin 20B. The other end 20C of the right first link 20 is connected to the floating link 17 via pin 20D.

[0036] The left second link 21 connects the intermediate portion of the left first link 19 in the longitudinal direction to the rod 16B of the hydraulic cylinder 16. The left second link 21 is formed of two plates facing each other with the rod 16B of the hydraulic cylinder 16 in between, and transmits the expansion and contraction force of the hydraulic cylinder 16 to the left first link 19. One end 21A of the left second link 21 is connected to the intermediate portion of the left first link 19 via a pin 21B. The other end 21C of the left second link 21 is connected to the tip of the rod 16B of the hydraulic cylinder 16 via a pin 16C.

[0037] The right second link 22 connects the intermediate portion of the right first link 20 in the longitudinal direction to the rod 16B of the hydraulic cylinder 16. The right second link 22 is formed of two plates facing each other with the rod 16B of the hydraulic cylinder 16 in between, and transmits the expansion and contraction force of the hydraulic cylinder 16 to the right first link 20. One end 22A of the right second link 22 is connected to the intermediate portion of the right first link 20 via a pin 22B. The other end 22C of the right second link 22 is connected to the tip of the rod 16B of the hydraulic cylinder 16 via a pin 16C. In other words, the pin 16C forms a connection between the left second link 21 and the right second link 22 and the hydraulic cylinder 16.

[0038] In this way, the three members, the other end 21C of the left second link 21, the other end 22C of the right second link 22, and the tip of the rod 16B of the hydraulic cylinder 16, are rotatably connected via a single common pin 16C. The expansion and contraction force of the hydraulic cylinder 16 is transmitted to the left first link 19 via the left second link 21, and is also transmitted to the right first link 20 via the right second link 22. As a result, the left first link 19 rotates left and right around the connecting part (pin 19D) with the floating link 17 as a fulcrum, and the right first link 20 rotates left and right around the connecting part (pin 20D) with the floating link 17 as a fulcrum.

[0039] 4, when the hydraulic cylinder 16 is extended, the upper-left connecting pin 13U connected to one end 19A of the left first link 19 is inserted into the left first pin insertion hole 9C of the left first bracket 9 and the left second pin insertion hole 11A of the left second bracket 11. Furthermore, the upper-right connecting pin 14U connected to one end 20A of the right first link 20 is inserted into the right first pin insertion hole 10C of the right first bracket 10 and the right second pin insertion hole 12A of the right second bracket 12. As a result, the left first bracket 9 and the left second bracket 11 are connected via the upper-left connecting pin 13U, and the right first bracket 10 and the right second bracket 12 are connected via the upper-right connecting pin 14U.

[0040] 6, when the hydraulic cylinder 16 is retracted, the left upper connecting pin 13U disengages from the left second pin insertion hole 11A of the left second bracket 11, and the right upper connecting pin 14U disengages from the right second pin insertion hole 12A of the right second bracket 12. This allows the left second bracket 11 to be separated from the left first bracket 9, and the right second bracket 12 to be separated from the right first bracket 10.

[0041] In this way, the connecting device 15 is displaced between a connected position (position shown in Figure 4) in which the upper left connecting pin 13U is inserted into the first left pin insertion hole 9C and the second left pin insertion hole 11A and the upper right connecting pin 14U is inserted into the first right pin insertion hole 10C and the second right pin insertion hole 12A, and a disconnected position (position shown in Figure 6) in which the upper left connecting pin 13U is removed from the second left pin insertion hole 11A and the upper right connecting pin 14U is removed from the second right pin insertion hole 12A, by the extension and contraction action of the hydraulic cylinder 16.

[0042] When the hydraulic cylinder 16 is retracted and the upper-left connecting pin 13U is removed from the left second pin insertion hole 11A, the upper-left connecting pin 13U remains inserted only through the left first pin insertion hole 9C of the left inner first bracket 9A. Furthermore, when the hydraulic cylinder 16 is retracted and the upper-right connecting pin 14U is removed from the right second pin insertion hole 12A, the upper-right connecting pin 14U remains inserted only through the right first pin insertion hole 10C of the right inner first bracket 10A. As a result, the connecting device 15 is held between the left inner first bracket 9A and the right inner first bracket 10A in a cantilevered state by the upper-left connecting pin 13U and the upper-right connecting pin 14U.

[0043] The left inner first bracket 9A of the left first bracket 9 and the right inner first bracket 10A of the right first bracket 10 are each provided with a rotation-preventing member 23. The rotation-preventing member 23 is made of a rectangular block body and is fixed to the inner surface of the left inner first bracket 9A and the inner surface of the right inner first bracket 10A at positions corresponding to the floating link 17. The rotation-preventing member 23 is disposed with a gap between the two plates that make up the floating link 17, and restricts the coupling device 15 from rotating about the left upper connecting pin 13U and the right upper connecting pin 14U.

[0044] The pin retention mechanism 24 is provided on the left second link 21 and the right second link 22. The pin retention mechanism 24 is composed of a pin 25 and an engaging member 26 (described later), and limits movement of the hydraulic cylinder 16 in the extension direction in the front connected state. As a result, the pin retention mechanism 24 prevents the upper-left connecting pin 13U inserted through the left first pin insertion hole 9C and the left second pin insertion hole 11A from falling out, and also prevents the upper-right connecting pin 14U inserted through the right first pin insertion hole 10C and the right second pin insertion hole 12A from falling out.

[0045] The pins 25 are provided on the two plates that make up the right second link 22. The pins 25 are made of cylindrical shafts and are fixed to the other end 22C of the right second link 22. The pins 25 are located adjacent to the pins 16C that connect the left second link 21 and the right second link 22 to the hydraulic cylinder 16, and protrude in a direction away from the hydraulic cylinder 16.

[0046] Engagement members 26 are provided on each of the two plates constituting left second link 21. Engagement members 26 are made of, for example, plates having the same thickness as left second link 21, and are fixed to a position adjacent to pin 16C on the outer circumferential edge of other end 21C of left second link 21. Engagement members 26 protrude in a direction perpendicular to the longitudinal direction of left second link 21, and recessed hooks 26A that engage with pin 25 are formed on the protruding end side of engagement members 26.

[0047] The hook 26A of the engaging member 26 engages with the pin 25 when the connecting device 15 is moved from the disconnected position shown in FIG. 6 to the connected position shown in FIG. 4 by the extension operation of the hydraulic cylinder 16, i.e., when the upper left connecting pin 13U is inserted into the first left pin insertion hole 9C and the second left pin insertion hole 11A, and the upper right connecting pin 14U is inserted into the first right pin insertion hole 10C and the second right pin insertion hole 12A.

[0048] Here, attention will be paid to the displacement of pins 16C, 21B, and 22B accompanying the extension operation of the hydraulic cylinder 16. As shown in Figures 6 and 7, when the upper-left connecting pin 13U is not inserted into the left first pin insertion hole 9C of the left outer first bracket 9B and the upper-right connecting pin 14U is not inserted into the right first pin insertion hole 10C of the right outer first bracket 10B, pins 21B and 22B are arranged in an isosceles triangle on the pin axis AA side of pin 16C. As shown in Figure 8, when the upper-left connecting pin 13U protrudes significantly from the left first pin insertion hole 9C of the left outer first bracket 9B and the upper-right connecting pin 14U protrudes significantly from the right first pin insertion hole 10C of the right outer first bracket 10B, the centers of pins 16C, 21B, and 22B are arranged on a straight line.

[0049] 4, when hook 26A of engagement member 26 is engaged with pin 25, pin 16C is arranged in an isosceles triangle on the pin axis AA side of pins 21B and 22B. Thus, in the front coupled state in which the lower boom 5A and the intermediate boom 5B are coupled by coupling device 15, the coupling portion (pin 16C) between left second link 21 and right second link 22 and hydraulic cylinder 16 is located on the pin axis AA side of the coupling portion (pin 21B) between left second link 21 and left first link 19 and the coupling portion (pin 22B) between right second link 22 and right first link 20.

[0050] In the front coupled state in which the lower boom 5A and the intermediate boom 5B are coupled by the coupling device 15, a force (force in the direction of arrow F) may act on the upper left connecting pin 13U and the upper right connecting pin 14U in a direction that moves them closer to each other along the pin axis AA, for example, due to vibrations during operation of the hydraulic excavator 1. When a force in the direction of arrow F acts on the upper left connecting pin 13U and the upper right connecting pin 14U in this way, a force acts in the extension direction on the rod 16B of the hydraulic cylinder 16. As a result, the coupling portions (pins 16C) between the left second link 21 and the right second link 22 and the hydraulic cylinder 16 attempt to move in a direction that moves closer to the pin axis AA.

[0051] In contrast, when the coupling device 15 is in the coupled position, the engagement member 26 (hook 26A) of the pin retention mechanism 24 engages with the pin 25, thereby preventing the hydraulic cylinder 16 (rod 16B) from moving further in the extension direction. Thus, in the front coupled state in which the lower boom 5A and the intermediate boom 5B are coupled by the coupling device 15, the pin retention mechanism 24 limits (prevents) the coupling portions (pins 16C) between the left second link 21 and the right second link 22 and the hydraulic cylinder 16 from moving in a direction approaching the pin axis AA due to movement of the hydraulic cylinder 16 in the extension direction. As a result, the upper left coupling pin 13U is prevented from falling out of the first left pin insertion hole 9C and the second left pin insertion hole 11A, and the upper right coupling pin 14U is prevented from falling out of the first right pin insertion hole 10C and the second right pin insertion hole 12A.

[0052] The left and right upper centering members 27 are provided on the end face of the base end side (lower boom 5A side) of the intermediate boom 5B. The left upper centering member 27 is located adjacent to the left first pin insertion hole 9C of the left inner first bracket 9A and has an arcuate portion that engages with the outer peripheral surface of the left upper connecting pin 13U. The right upper centering member 27 is located adjacent to the right first pin insertion hole 10C of the right inner first bracket 10A and has an arcuate portion that engages with the outer peripheral surface of the right upper connecting pin 14U. These left and right upper centering members 27 guide the left upper connecting pin 13U and the right upper connecting pin 14U so that they align with the pin axis AA during the operation of connecting the intermediate boom 5B and the lower boom 5A, thereby centering the left upper connecting pin 13U and the right upper connecting pin 14U.

[0053] The left and right lower centering members 28 are located below the upper centering member 27 and are provided on the end surface of the base end of the intermediate boom 5B. The left lower centering member 28 is located adjacent to the left first pin insertion hole 9C of the left inner first bracket 9A and has an arcuate portion that engages with the outer peripheral surface of the left lower connecting pin 13L. The right lower centering member 28 is located adjacent to the right first pin insertion hole 10C of the right inner first bracket 10A and has an arcuate portion that engages with the outer peripheral surface of the right lower connecting pin 14L. These left and right lower centering members 28 guide the left lower connecting pin 13L and the right lower connecting pin 14L so that they are aligned with the pin axis AA during the operation of connecting the intermediate boom 5B and the lower boom 5A, thereby centering the left lower connecting pin 13L and the right lower connecting pin 14L.

[0054] Next, a description will be given of the left and right connecting pin abutment members 29 used in this embodiment. As shown in Figures 3 to 5, the left connecting pin abutment member 29 is provided on the outer surface of the left outer first bracket 9B (the surface opposite to the left inner first bracket 9A), and the right connecting pin abutment member 29 is provided on the outer surface of the right outer first bracket 10B (the surface opposite to the right inner first bracket 10A).

[0055] 4, in the front connected state in which the lower boom 5A and the intermediate boom 5B are connected by the connecting device 15, movement of the hydraulic cylinder 16 in the extension direction is restricted by the pin retaining mechanism 24. As a result, the pin retaining mechanism 24 prevents the upper left connecting pin 13U from coming off the left second bracket 11 (left second pin insertion hole 11A) and the upper right connecting pin 14U from coming off the right second bracket 12 (right second pin insertion hole 12A).

[0056] In response to this, for example, due to vibrations during operation of the hydraulic excavator 1, a force (force in the direction of arrow F') may act on the upper left connecting pin 13U and the upper right connecting pin 14U in a direction that moves them away from each other along the pin axis AA. When a force in the direction of arrow F' acts on the upper left connecting pin 13U and the upper right connecting pin 14U in the front connected state, a force in the contracting direction acts on the hydraulic cylinder 16, and the pin 16C, which connects the left second bracket 11 and the right second bracket 12 to the hydraulic cylinder 16, moves in a direction away from the pin axis AA. As a result, the coupling device 15 may transition from the connected position shown in FIG. 4 to the positions shown in FIGS. 8 and 7, and then to the disconnected position shown in FIG. 6, which may cause the upper left connecting pin 13U to disengage from the left second bracket 11 and the upper right connecting pin 14U to disengage from the right second bracket 12.

[0057] 8 before transitioning from the connected position of Fig. 4 to the disconnected position of Fig. 6, the connection portion (pin 16C) between the left second link 21 and the right second link 22 and the hydraulic cylinder 16, the connection portion (pin 21B) between the left second link 21 and the left first link 19, and the connection portion (pin 22B) between the right second link 22 and the right first link 20 are aligned in a straight line. In this state, the left upper connecting pin 13U protrudes significantly from the outer surface of the left outer first bracket 9B, and the right upper connecting pin 14U protrudes significantly from the outer surface of the right outer first bracket 10B.

[0058] When the pin 16C, which connects the left second bracket 11 and the right second bracket 12 to the hydraulic cylinder 16, moves in a direction away from the pin axis AA, the left and right connecting pin abutment members 29 abut against the cylindrical protrusion 30 of the upper-left connecting pin 13U and the cylindrical protrusion 30 of the upper-right connecting pin 14U, thereby limiting the movement of the upper-left connecting pin 13U and the upper-right connecting pin 14U. The left connecting pin abutment member 29 is disposed in the left outer first bracket 9B near the left first pin insertion hole 9C through which the upper-left connecting pin 13U is inserted, and the left connecting pin abutment member 29 is disposed in the right outer first bracket 10B near the right first pin insertion hole 10C through which the upper-right connecting pin 14U is inserted. Since the left and right connecting pin abutment members 29 have the same configuration, only the left connecting pin abutment member 29 will be described below.

[0059] 3 to 5, connecting pin abutment member 29 is formed from a plate bent into an L-shape and is located near left second pin insertion hole 11A, through which upper-left connecting pin 13U is inserted, and is fixed to the outer surface of left second bracket 11. Connecting pin abutment member 29 is fixed to left second bracket 11 by means of welding or the like, and has a fixed portion 29A protruding from left second bracket 11, and a pin abutment portion 29B bent from the protruding end of fixed portion 29A toward left second bracket 11 and facing left second bracket 11 at a fixed distance. Pin abutment portion 29B abuts against cylindrical protrusion 30 of upper-left connecting pin 13U, thereby limiting (prohibiting) further movement of upper-left connecting pin 13U.

[0060] The pin abutment portion 29B is disposed on the pin axis AA, and four through holes 29C are formed in the pin abutment portion 29B, penetrating in the plate thickness direction (left-right direction). These four through holes 29C constitute an abutment member side engaging portion, and are formed at 90° intervals on a circumference centered on the pin axis AA. In addition, two L-shaped reinforcing ribs 29D are fixed at intervals in the vertical direction to the outer surfaces of the fixing portion 29A and the pin abutment portion 29B (the surfaces opposite to the left second bracket 11).

[0061] Four convex columnar projections 30 serving as pin-side engaging portions are fixed to the end face 13U1 of the upper-left connecting pin 13U that faces the connecting pin abutment member 29 (pin abutment portion 29B). These four columnar projections 30 are arranged at 90° intervals on a circle centered on the pin axis AA and form part of the upper-left connecting pin 13U. The circumference centered on the pin axis AA on which the four columnar projections 30 are arranged has the same diameter as the circumference centered on the pin axis AA on which the four through holes 29C of the connecting pin abutment member 29 are arranged. The diameter of the columnar projections 30 is set slightly smaller than the diameter of the through holes 29C.

[0062] Therefore, when the upper-left connecting pin 13U is moved toward the connecting pin abutment member 29 in a state where the circumferential positions of the four columnar projections 30 and the circumferential positions of the four through holes 29C are aligned about the pin axis AA, the four columnar projections 30 each fit into the through holes 29C, as shown in Fig. 8. On the other hand, when the upper-left connecting pin 13U is moved toward the connecting pin abutment member 29 in a state where the positions of the four columnar projections 30 and the positions of the four through holes 29C do not match, as shown in Fig. 10, the four columnar projections 30 abut against the pin abutment portions 29B of the connecting pin abutment member 29 without fitting into the through holes 29C, and further movement of the upper-left connecting pin 13U is prohibited.

[0063] Like the left connecting pin abutment member 29, the right connecting pin abutment member 29 has a fixing portion 29A, a pin abutment portion 29B, four through holes 29C, and two reinforcing ribs 29D. Four columnar protrusions 30 corresponding to the four through holes 29C are fixed to the end face 14U1 of the right connecting pin 14U, and these columnar protrusions 30 constitute part of the right connecting pin 14U. Therefore, when the right upper connecting pin 14U is moved toward the connecting pin abutment member 29 with the positions of the four columnar protrusions 30 aligned with the positions of the four through holes 29C, the four columnar protrusions 30 fit into the through holes 29C (see FIG. 8). On the other hand, when the positions of the four cylindrical protrusions 30 and the four through holes 29C do not match and the upper right connecting pin 14U is moved toward the connecting pin abutment member 29, the four cylindrical protrusions 30 abut against the pin abutment portion 29B of the connecting pin abutment member 29 without fitting into the through holes 29C, and further movement of the upper right connecting pin 14U is prohibited (see Figure 10).

[0064] A retaining plate 31 is attached to an axial end face 13L1 of the lower-left connecting pin 13L and an axial end face 14L1 of the lower-right connecting pin 14L, respectively. The retaining plate 31 is formed of a plate having a circular portion with a larger diameter than the lower-left connecting pin 13L and the lower-right connecting pin 14L, and is attached to the end face 13L1 of the lower-left connecting pin 13L and the end face 14L1 of the lower-right connecting pin 14L using a plurality of bolts 31A. As a result, in the front connected state shown in FIG. 4 , even if a force in the direction of arrow F or F′ acts on the lower-left connecting pin 13L and the lower-right connecting pin 14L due to vibrations during operation of the hydraulic excavator 1, the retaining plate 31 abuts against the left outer first bracket 9B and the right outer first bracket 10B, thereby preventing the lower-left connecting pin 13L and the lower-right connecting pin 14L from coming out.

[0065] The working device 4 of the hydraulic excavator 1 according to this embodiment has the configuration described above, and the operation of connecting the lower boom 5A and the intermediate boom 5B of the working device 4 will be described below.

[0066] First, as shown in Fig. 11, the working implement 4 detached from the lower boom 5A is placed on the ground using the support 100, and the intermediate boom 5B and upper boom 5C are held so that they extend along the ground. Meanwhile, with the lower boom 5A attached to the upper rotating body 3 tilted toward the ground, the hydraulic excavator 1 is self-propelled toward the working implement 4, and the tip of the lower boom 5A, to which the first left bracket 9 and the first right bracket 10 are attached, is positioned toward the base end of the intermediate boom 5B, to which the second left bracket 11 and the second right bracket 12 are attached.

[0067] 6, with the hydraulic cylinder 16 of the upper coupling device 15 retracted, the upper-left coupling pin 13U is inserted into the left first pin insertion hole 9C of the left inner first bracket 9A, and the upper-right coupling pin 14U is inserted into the right first pin insertion hole 10C of the right inner first bracket 10A. Meanwhile, with the hydraulic cylinder 16 of the lower coupling device 15 retracted, the lower-left coupling pin 13L is inserted into the left first pin insertion hole 9C of the left inner first bracket 9A, and the lower-right coupling pin 14L is inserted into the right first pin insertion hole 10C of the right inner first bracket 10A. As a result, the upper connecting device 15 is held between the left inner first bracket 9A and the right inner first bracket 10A via the upper left connecting pin 13U and the upper right connecting pin 14U, and the lower connecting device 15 is held between the left inner first bracket 9A and the right inner first bracket 10A via the lower left connecting pin 13L and the lower right connecting pin 14L.

[0068] Next, the left second bracket 11 provided on the intermediate boom 5B is inserted between the left inner first bracket 9A and the left outer first bracket 9B, and the right second bracket 12 provided on the intermediate boom 5B is inserted between the right inner first bracket 10A and the right outer first bracket 10B provided on the lower boom 5A. Then, the left second pin insertion hole 11A of the left second bracket 11 is aligned on the same pin axis AA as the left first pin insertion hole 9C of the left first bracket 9, and the right second pin insertion hole 12A of the right second bracket 12 is aligned on the same pin axis AA as the right first pin insertion hole 10C of the right first bracket 10.

[0069] In this case, by supporting the working device 4 using the support tool 100, when the left first pin insertion hole 9C of the left first bracket 9 and the left second pin insertion hole 11A of the left second bracket 11 are aligned, the four columnar protrusions 30 fixed to the upper left connecting pin 13U and the four through holes 29C formed in the connecting pin abutment member 29 are preset to coincide in the circumferential direction. Similarly, when the right first pin insertion hole 10C of the right first bracket 10 and the right second pin insertion hole 12A of the right second bracket 12 are aligned, the four columnar protrusions 30 fixed to the upper right connecting pin 14U and the four through holes 29C formed in the connecting pin abutment member 29 are preset to coincide in the circumferential direction.

[0070] In this state, hydraulic cylinder 16 of upper connecting device 15 is extended by supplying pressure oil to it. As a result, as shown in Fig. 7, one end 19A of left first link 19 rotates around pin 19D as a fulcrum in a direction approaching left first bracket 9, and upper left connecting pin 13U is inserted into left second pin insertion hole 11A of left second bracket 11. Similarly, one end 20A of right first link 20 rotates around pin 20D as a fulcrum in a direction approaching right first bracket 10, and upper right connecting pin 14U is inserted into right second pin insertion hole 12A of right second bracket 12.

[0071] Further extending the hydraulic cylinder 16 causes pins 16C, 21B, and 22B to align in a straight line, maximizing the distance between the upper-left connecting pin 13U and the upper-right connecting pin 14U, as shown in Fig. 8. In this state, the upper-left connecting pin 13U is inserted through the left first pin insertion hole 9C of the left first bracket 9 and the left second pin insertion hole 11A of the left second bracket 11, and the upper-right connecting pin 14U is inserted through the right first pin insertion hole 10C of the right first bracket 10 and the right second pin insertion hole 12A of the right second bracket 12.

[0072] Here, when the working device 4 is supported using the support tool 100, the four columnar protrusions 30 of the upper-left connecting pin 13U and the four through holes 29C of the connecting pin abutment member 29 are set to circumferentially coincide with each other, and the four columnar protrusions 30 of the upper-right connecting pin 14U and the four through holes 29C of the connecting pin abutment member 29 are set to circumferentially coincide with each other. As a result, the columnar protrusions 30 of the upper-left connecting pin 13U are inserted into the through holes 29C of the connecting pin abutment member 29, and the columnar protrusions 30 of the upper-right connecting pin 14U are inserted into the through holes 29C of the connecting pin abutment member 29. This makes it possible to avoid the columnar protrusions 30 of the upper-left connecting pin 13U and the columnar protrusions 30 of the upper-right connecting pin 14U abutting against the connecting pin abutment member 29 (pin abutment portions 29B), which would restrict (prohibit) the extension operation of the hydraulic cylinder 16.

[0073] When the hydraulic cylinder 16 is further extended from the state shown in FIG. 8 , as shown in FIG. 9 , pin 16C moves closer to the pin axis AA than pins 21B and 22B. Therefore, the upper-left connecting pin 13U and the upper-right connecting pin 14U move toward each other, and the extension of the hydraulic cylinder 16 stops when the hook 26A of the engaging member 26 provided on the left second link 21 engages with the pin 25 provided on the right second link 22. As a result, the upper-left connecting pin 13U connects the left first bracket 9 and the left second bracket 11 with the cylindrical projection 30 disengaged from the through-hole 29C of the connecting pin abutment member 29. Similarly, the upper-right connecting pin 14U connects the right first bracket 10 and the right second bracket 12 with the cylindrical projection 30 disengaged from the through-hole 29C of the connecting pin abutment member 29.

[0074] 12, the left first bracket 9 of the lower boom 5A and the left second bracket 11 of the intermediate boom 5B are connected via the left upper connecting pin 13U, and the right first bracket 10 of the lower boom 5A and the right second bracket 12 of the intermediate boom 5B are connected via the right upper connecting pin 14U. The work of connecting the lower boom 5A and the intermediate boom 5B using this left upper connecting pin 13U and right upper connecting pin 14U is performed at a position high above the ground, but this connecting work does not require the worker to work at a height, and the connecting work can be performed safely and quickly using the upper connecting device 15.

[0075] After the lower boom 5A and the intermediate boom 5B are connected via the upper left connecting pin 13U and the upper right connecting pin 14U, the tip of the lower boom 5A attached to the hydraulic excavator 1 is rotated upward as shown in FIG. 13. When the lower boom 5A rotates upward, the intermediate boom 5B rotates around the upper left connecting pin 13U and the upper right connecting pin 14U within the range of an acute angle indicated by angle θ in FIG. 12, and the lower left connecting pin 13L and the lower right connecting pin 14L abut against the lower centering member 28. As a result, the lower left connecting pin 13L is centered with the left second pin insertion hole 11A of the left second bracket 11, and the lower right connecting pin 14L is centered with the right second pin insertion hole 12A of the right second bracket 12. In this state, pressure oil is supplied to the hydraulic cylinder 16 of the lower connecting device 15, thereby extending the hydraulic cylinder 16.

[0076] 4, the left-lower connecting pin 13L is thereby inserted into the left-second pin insertion hole 11A of the left-second bracket 11 and the left-first pin insertion hole 9C of the left-outer first bracket 9B. Similarly, the right-lower connecting pin 14L is inserted into the right-second pin insertion hole 12A of the right-second bracket 12 and the right-first pin insertion hole 10C of the right-outer first bracket 10B. In this state, retaining plates 31 are fixed to end faces 13L1 of the left-lower connecting pin 13L and 14L1 of the right-lower connecting pin 14L using bolts 31A, respectively, to prevent the left-lower connecting pin 13L and the right-lower connecting pin 14L from coming out.

[0077] In this way, the intermediate boom 5B of the working implement 4 supported by the support tool 100 can be connected to the lower boom 5A attached to the hydraulic excavator 1 via the upper left connecting pin 13U, upper right connecting pin 14U, lower left connecting pin 13L, and lower right connecting pin 14L. After connecting the lower boom 5A and the intermediate boom 5B, the boom 5 can be raised as shown in FIG. 1, allowing the working implement 4 to be used for work such as dismantling a structure.

[0078] Here, when the hydraulic excavator 1 is operating, due to vibrations and the like generated by the hydraulic excavator 1, a force may act on the upper left connecting pin 13U and the upper right connecting pin 14U in a direction that moves them closer to each other along the pin axis AA (a force in the direction of arrow F in Figure 4), or a force that moves them away from each other along the pin axis AA (a force in the direction of arrow F' in Figure 4).

[0079] When a force in the direction of arrow F acts on the upper-left connecting pin 13U and the upper-right connecting pin 14U, a force acts in the extension direction on the rod 16B of the hydraulic cylinder 16. At this time, when the coupling device 15 is in the coupled position, the engaging member 26 (hook 26A) of the pin retention mechanism 24 engages with the pin 25, thereby preventing the hydraulic cylinder 16 (rod 16B) from moving further in the extension direction. As a result, in the front coupled state in which the lower boom 5A and the intermediate boom 5B are coupled by the coupling device 15, even if a force in the direction of arrow F acts on the upper-left connecting pin 13U and the upper-right connecting pin 14U, the pin retention mechanism 24 can prevent the upper-left connecting pin 13U from coming out of the first left pin insertion hole 9C and the second left pin insertion hole 11A, and can prevent the upper-right connecting pin 14U from coming out of the first right pin insertion hole 10C and the second right pin insertion hole 12A.

[0080] On the other hand, when a force in the direction of arrow F' acts on the upper left connecting pin 13U and the upper right connecting pin 14U, a force in the contracting direction acts on the rod 16B of the hydraulic cylinder 16. If the hydraulic cylinder 16 moves in the contracting direction, the pin 16C, which is the connection portion between the hydraulic cylinder 16 and the left second bracket 11 and the right second bracket 12, moves in a direction away from the pin axis AA, and the coupling device 15 transitions from the connected position shown in Figure 4 to the positions shown in Figures 8 and 7, and then to the disconnected position shown in Figure 6.

[0081] In contrast, in this embodiment, connecting pin abutment members 29 are fixed to the left second bracket 11 and the right second bracket 12. Therefore, even if the upper-left connecting pin 13U protrudes from the left outer first bracket 9B and the upper-right connecting pin 14U protrudes from the right outer first bracket 10B as the pin 16C moves in a direction away from the pin axis AA, the columnar protrusions 30 of the upper-left connecting pin 13U and the upper-right connecting pin 14U abut against the pin abutment portion 29B of the connecting pin abutment member 29, as shown in FIG.

[0082] During the operation of connecting the lower boom 5A and the intermediate boom 5B described above, the four cylindrical projections 30 fixed to the upper-left connecting pin 13U and the upper-right connecting pin 14U are set to align with the four through holes 29C formed in the connecting pin abutment member 29. Therefore, when the hydraulic cylinder 16 contracts and the pin 16C moves away from the pin axis AA, the upper-left connecting pin 13U protrudes from the left outer first bracket 9B and the upper-right connecting pin 14U protrudes from the right outer first bracket 10B, and the cylindrical projections 30 of the upper-left connecting pin 13U and the upper-right connecting pin 14U are housed in the through holes 29C of the connecting pin abutment member 29 (see FIG. 8 ).

[0083] After the lower boom 5A and the intermediate boom 5B are connected via the upper-left connecting pin 13U and the upper-right connecting pin 14U in this manner, the distal end of the lower boom 5A is rotated upward to rotate the intermediate boom 5B about the upper-left connecting pin 13U and the upper-right connecting pin 14U, thereby aligning the lower-left connecting pin 13L and the lower-right connecting pin 14L. At this time, the intermediate boom 5B rotates within an acute angle θ about the upper-left connecting pin 13U and the upper-right connecting pin 14U (see FIG. 12). Therefore, the four cylindrical protrusions 30 fixed to the upper-left connecting pin 13U and the upper-right connecting pin 14U abut against the pin abutment portion 29B without engaging with the four through-holes 29C formed in the connecting pin abutment member 29.

[0084] 10, further movement of the upper-left connecting pin 13U and the upper-right connecting pin 14U is prohibited by the cylindrical projections 30 of the upper-left connecting pin 13U and the upper-right connecting pin 14U coming into contact with the connecting pin abutment member 29. As a result, in the front connected state in which the lower boom 5A and the intermediate boom 5B are connected by the connecting device 15, even if a force in the direction of arrow F' acts on the upper-left connecting pin 13U and the upper-right connecting pin 14U, the connecting pin abutment member 29 can prevent the upper-left connecting pin 13U from coming out of the first left pin insertion hole 9C and the second left pin insertion hole 11A, and can prevent the upper-right connecting pin 14U from coming out of the first right pin insertion hole 10C and the second right pin insertion hole 12A.

[0085] Thus, in the embodiment, in the working device 4 of the hydraulic excavator 1, in a front coupled state in which the lower boom 5A and the intermediate boom 5B are coupled by the coupling device 15, the pin 16C that is the coupling portion between the left second link 21 and the right second link 22 and the hydraulic cylinder 16 is located closer to the pin axis AA than the pin 21B that is the coupling portion between the left second link 21 and the left first link 19 and the pin 22B that is the coupling portion between the right second link 22 and the right first link 20. The left second bracket 11 member and the right second bracket 12 are provided with a pin stop mechanism 24 that restricts movement of the pin 16C, which is the connecting portion between the left second link 21 and the right second link 22 and the hydraulic cylinder 16, in a direction approaching the pin axis AA, and the left second bracket 11 member and the right second bracket 12 are provided with connecting pin abutment members 29 that abut against the left upper connecting pin 13U and the right upper connecting pin 14U to restrict its movement when the pin 16C, which is the connecting portion between the left second link 21 and the right second link 22 and the hydraulic cylinder 16, moves in a direction away from the pin axis AA in the front connected state.

[0086] According to this configuration, when a force acts on the upper-left connecting pin 13U and the upper-right connecting pin 14U in a direction moving them toward each other due to vibrations or the like during operation of the hydraulic excavator 1, the upper-left connecting pin 13U and the upper-right connecting pin 14U can be prevented from coming out by the pin retaining mechanism 24. On the other hand, when a force acts on the upper-left connecting pin 13U and the upper-right connecting pin 14U in a direction moving them away from each other, the connecting pin abutment member 29 can prevent the upper-left connecting pin 13U and the upper-right connecting pin 14U from coming out.

[0087] In the embodiment, the axial end faces 13U1 and 14U1 of the upper left connecting pin 13U and the upper right connecting pin 14U that face the connecting pin abutment member are provided with cylindrical protrusions 30 that are convex or concave in the axial direction, and the connecting pin abutment member 29 is provided with a concave or convex through hole 29C that engages with the cylindrical protrusions 30. With this configuration, the cylindrical protrusions 30 abut against the connecting pin abutment member 29 to prohibit movement of the upper left connecting pin 13U and the upper right connecting pin 14U, thereby preventing the upper left connecting pin 13U and the upper right connecting pin 14U from coming out, for example, in the front connecting state. Meanwhile, the cylindrical protrusions 30 are inserted into the through holes 29C, allowing the upper left connecting pin 13U and the upper right connecting pin 14U to protrude from the left first bracket 9 and the right first bracket 10, for example, during the operation of connecting the lower boom 5A and the intermediate boom 5B.

[0088] In this embodiment, the left connecting pin 13 has an upper-left connecting pin 13U and a lower-left connecting pin 13L that form a pair in the vertical direction when connecting the lower boom 5A and the intermediate boom 5B, and the right connecting pin 14 has an upper-right connecting pin 14U and a lower-right connecting pin 14L that form a pair in the vertical direction when connecting the lower boom 5A and the intermediate boom 5B, and the connecting pin abutment member 29 is provided at a position where the upper-left connecting pin 13U and the upper-right connecting pin 14U abut. With this configuration, for example, when connecting the lower boom 5A and the intermediate boom 5B, the lower boom 5A and the intermediate boom 5B are connected via the upper-left connecting pin 13U and the upper-right connecting pin 14U and can be prevented from coming out by the connecting pin abutment member 29. This allows the intermediate boom 5B to be rotated around the upper left connecting pin 13U and the upper right connecting pin 14U relative to the lower boom 5A, and the work of connecting the lower boom 5A and the intermediate boom 5B using the lower left connecting pin 13L and the lower right connecting pin 14L to be carried out quickly and safely.

[0089] In the embodiment, the columnar protrusion 30 abuts against the connecting pin abutment member 29 in the front connected state in which the lower boom 5A and the intermediate boom 5B are connected, and engages with the through hole 29C of the connecting pin abutment member 29 during the operation of connecting the lower boom 5A and the intermediate boom 5B. With this configuration, in the front connected state in which the lower boom 5A and the intermediate boom 5B are connected, the columnar protrusion 30 abuts against the connecting pin abutment member 29, thereby preventing the upper left connecting pin 13U and the upper right connecting pin 14U from coming out. On the other hand, during the operation of connecting the lower boom 5A and the intermediate boom 5B, the columnar protrusions 30 of the upper left connecting pin 13U and the upper right connecting pin 14U engage with the through hole 29C without abutting against the pin abutment portion 29B of the connecting pin abutment member 29, allowing the connecting operation to be performed smoothly.

[0090] In this embodiment, the pin retaining mechanism 24 is composed of a pin 25 provided on one of the left second link 21 and the right second link 22, and an engaging member 26 provided on the other of the left second link 21 and the right second link 22, which engages with the pin 25 to limit the extension of the hydraulic cylinder 16 after the left connecting pin 13 is inserted into the left first pin insertion hole 9C and the left second pin insertion hole 11A and the right connecting pin 14 is inserted into the right first pin insertion hole 10C and the right second pin insertion hole 12A due to the extension of the hydraulic cylinder 16. With this configuration, displacement of the left second link 21 and the right second link 22 is prohibited when the engaging member 26 is engaged with the pin 25, so further extension of the hydraulic cylinder 16 can be limited and the left connecting pin 13 and the right connecting pin 14 can be prevented from falling out.

[0091] Next, Figure 14 shows a second embodiment of the present invention. A feature of this embodiment is that the pin retention mechanism is configured by a stopper that abuts against the left second link and the right second link to limit the extension operation of the hydraulic cylinder. In this embodiment, the same components as those in the first embodiment are given the same reference numerals, and their description will be omitted.

[0092] Upper and lower stoppers 32 serving as pin removal prevention mechanisms are provided between the left first bracket 9 and the right first bracket 10. The upper stopper 32 is disposed on the opposite side of the upper coupling device 15 to the upper coupling device 15 across the pin axis AA of the upper-left connecting pin 13U and the upper-right connecting pin 14U, and the lower stopper 32 is disposed on the opposite side of the lower coupling device 15 to the pin axis AA of the lower-left connecting pin 13L and the lower-right connecting pin 14L. The upper stopper 32 is abutted by the left second link 21 and the right second link 22 of the upper coupling device 15, thereby limiting the extension of the hydraulic cylinder 16, and the lower stopper 32 is abutted by the left second link 21 and the right second link 22 of the lower coupling device 15, thereby limiting the extension of the hydraulic cylinder 16.

[0093] These upper and lower stoppers 32 are fixed with bolts 33 to the end face of the lower boom 5A that faces the intermediate boom 5B, and have link abutment portions 32A that protrude toward the other end 21C of the left second link 21 and the other end 22C of the right second link 22. When the connecting device 15 is in the connected posture shown in Fig. 14, the other end 21C of the left second link 21 and the other end 22C of the right second link 22 abut against the link abutment portions 32A of the stoppers 32, thereby prohibiting further extension of the hydraulic cylinder 16 (rod 16B).

[0094] The connecting device 15 according to the second embodiment has the upper and lower stoppers 32 as described above, and when the connecting device 15 is in the connected position shown in FIG. 14 and pin 16C is positioned closer to the pin axis AA than pins 21B and 22B, the other end 21C of the left second link 21 and the other end 22C of the right second link 22 abut against the link abutment portion 32A of the stopper 32. This prevents further extension of the hydraulic cylinder 16 by the stopper 32. As a result, the upper-left connecting pin 13U and the lower-left connecting pin 13L are prevented from coming out of the left first bracket 9 and the left second bracket 11, and the upper-right connecting pin 14U and the lower-right connecting pin 14L are prevented from coming out of the right first bracket 10 and the right second bracket 12.

[0095] In the first embodiment, the pin 25 provided on the right second link 22 and the engaging member 26 provided on the left second link 21 constitute the pin dropout prevention mechanism 24, and the engaging member 26 engages with the pin 25 to limit the extension operation of the hydraulic cylinder 16. In the second embodiment, a stopper 32 is provided between the left first bracket 9 and the right first bracket 10, and the left second link 21 and the right second link 22 abut against the stopper 32 to limit the extension operation of the hydraulic cylinder 16. However, the present invention is not limited to this, and the pin dropout prevention mechanism may be constituted by, for example, the stroke end on the extension side of the hydraulic cylinder 16. That is, the hydraulic cylinder 16 may be configured to reach the stroke end when the hydraulic cylinder 16 is extended, the left connecting pin 13 is inserted into the left first pin insertion hole 9C of the left first bracket 9 and the left second pin insertion hole 11A of the left second bracket 11, and the right connecting pin 14 is inserted into the right first pin insertion hole 10C of the right first bracket 10 and the right second pin insertion hole 12A of the right second bracket 12.

[0096] Furthermore, in the embodiment, the upper left connecting pin 13U and the upper right connecting pin 14U are provided with cylindrical protrusions 30 as pin-side engaging portions, and through holes 29C as abutment-member-side engaging portions are provided in the connecting pin abutment member 29. However, the present invention is not limited to this, and, for example, a configuration in which concave pin-side engaging portions are provided in the upper left connecting pin 13U and the upper right connecting pin 14U, and convex abutment-member-side engaging portions are provided in the connecting pin abutment member 29 may also be used.

[0097] Furthermore, in the embodiment, the upper left connecting pin 13U and the upper right connecting pin 14U are provided with four columnar protrusions 30 arranged at equal intervals on a circumference centered on the pin axis AA, and the connecting pin abutment member 29 is provided with four through holes 29C arranged at equal intervals on the same circumference as the columnar protrusions 30 centered on the pin axis AA. However, the present invention is not limited to this, and for example, the upper left connecting pin 13U and the upper right connecting pin 14U may be provided with one or more columnar protrusions on the circumference centered on the pin axis AA, and the connecting pin abutment member 29 may be provided with one or more through holes on the same circumference as the columnar protrusions centered on the pin axis AA.

[0098] Furthermore, in the embodiment, the case where the coupling device 15 is used at the connecting portion between the lower boom 5A and the intermediate boom 5B that constitute the boom 5 of the working device 4 is exemplified. However, the present invention is not limited to this, and a coupling device may also be used at the connecting portion between the intermediate boom 5B and the upper boom 5C, for example. [Explanation of symbols]

[0099] 5A Lower boom (first front member) 5B Intermediate boom (second front member) 9 Left first bracket (left first component) 9C Left first pin insertion hole 10 Right first bracket (right first member) 10C Right first pin insertion hole 11 Left second bracket (left second member) 12 Right second bracket (right second member) 13 Left connecting pin 13U upper left connecting pin 13L Lower left connecting pin 14 Right connecting pin 14U upper right connecting pin 14L Lower right connecting pin 15 Coupling device 16 Hydraulic cylinder 16C, 21B, 22B pin (connection part) 17 Floating Links 19 Left 1st link 20 Right 1st link 21 Left 2nd link 22 Right second link 24-pin retaining mechanism 25-pin 26 Engagement member 29 Connecting pin abutment member 29C Through hole (contact member side engagement part) 30 Cylindrical protrusion (pin side engagement member)

Claims

1. a first front member having a left first member in which a left first pin insertion hole is formed and a right first member in which a right first pin insertion hole is formed; a second front member having a left second member in which a left second pin insertion hole is formed and a right second member in which a right second pin insertion hole is formed; and a connecting device that connects the first front member and the second front member; The connecting device includes a left connecting pin inserted into the left first pin insertion hole and the left second pin insertion hole; a right connecting pin inserted through the right first pin insertion hole and the right second pin insertion hole; a hydraulic cylinder disposed at a position spaced apart from the pin axes of the left connecting pin and the right connecting pin; a floating link attached to either a tube or a rod of the hydraulic cylinder and disposed in a floating state so as to be movable in a direction approaching or moving away from the pin axis; a left first link having one end connected to the left connecting pin and the other end connected to the floating link; a right first link having one end connected to the right connecting pin and the other end connected to the floating link; a left second link having one end connected to an intermediate portion of the left first link and the other end connected to the other of the tube or rod of the hydraulic cylinder; a right second link having one end connected to an intermediate portion of the right first link and the other end connected to the other of the tube or rod of the hydraulic cylinder, In a front coupled state in which the first front member and the second front member are coupled by the coupling device, coupling portions between the left second link and the right second link and the hydraulic cylinder are located closer to the pin axis than coupling portions between the left second link and the left first link and between the right second link and the right first link, the connecting device includes a pin removal prevention mechanism that restricts movement of connecting portions between the left second link and the right second link and the hydraulic cylinder in a direction approaching the pin axis in the front connected state, a connecting pin abutment member provided on the left second member and the right second member that abuts against the left connecting pin and the right connecting pin to limit their movement when the connection portions between the left second link and the right second link and the hydraulic cylinder move in a direction away from the pin axis in the front connected state.

2. a pin-side engaging portion having a convex or concave shape in the axial direction is provided on an end surface of each of the left connecting pin and the right connecting pin that faces the connecting pin abutment member, 2. A working device for a construction machine according to claim 1, wherein the connecting pin abutment member is provided with an abutment member side engaging portion that is concave or convex and engages with the pin side engaging portion.

3. the left connecting pin includes an upper left connecting pin and a lower left connecting pin that form a pair in the up-down direction during a connecting operation between the first front member and the second front member, the right connecting pin includes an upper right connecting pin and a lower right connecting pin that form a pair in the up-down direction during a connecting operation between the first front member and the second front member, 3. The working device for a construction machine according to claim 2, wherein the connecting pin abutment member is provided at a position where the upper left connecting pin and the upper right connecting pin abut against each other.

4. 3. A work device for a construction machine as described in claim 2, characterized in that the pin side engagement portion abuts against the connecting pin abutment member in the front connected state, and engages with the abutment member side engagement portion during the connecting operation of the first front member and the second front member.

5. 2. The working device for a construction machine according to claim 1, wherein the pin retention mechanism is provided at a stroke end of the hydraulic cylinder.

6. The pin retaining mechanism includes a pin provided on one of the left second link and the right second link; 2. The working device of a construction machine according to claim 1, further comprising an engaging member that is provided on the other of the left second link and the right second link, and that engages with the pin to limit the extension operation of the hydraulic cylinder after the left connecting pin is inserted into the left first pin insertion hole and the left second pin insertion hole and the right connecting pin is inserted into the right first pin insertion hole and the right second pin insertion hole due to the extension operation of the hydraulic cylinder.

7. 2. A working device for a construction machine according to claim 1, wherein the pin withdrawal prevention mechanism is configured as a stopper that is provided between the left first member and the right first member and that abuts against the left second link and the right second link to limit the extension movement of the hydraulic cylinder after the left connecting pin is inserted into the left first pin insertion hole and the left second pin insertion hole and the right connecting pin is inserted into the right first pin insertion hole and the right second pin insertion hole due to the extension movement of the hydraulic cylinder.

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