Attachment detachment device for construction machine and construction machine equipped with same

Abstract

To provide an attachment attaching / detaching device for a construction machine capable of keeping a connected state of an attachment even when power to a hydraulic cylinder is cut off to achieve high safety.SOLUTION: An attachment attaching / detaching device 30 is provided with: a fixing frame 31 having a first hook 33; a moveable frame 32 having a second hook 34 and movably provided on the fixing frame 31; a first hydraulic cylinder 55 moving the movable frame 32 with respect to the fixing frame 31; a rear lock member 48 provided on the fixing frame 31; a second hydraulic cylinder 56 provided on the fixing frame 31 and rotating the rear lock member 48 to an unlock position after being biased to a lock position with a lock spring; a front lock member 58 provided on the moveable frame 32 and biased to the lock position with the lock spring; and a third hydraulic cylinder 57 provided on the moveable frame 32 and rotating the front lock member 58 to the unlock position.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an attachment attaching / detaching device for a construction machine that connects a work attachment of the construction machine to an arm of a working device, and to a construction machine equipped with the same. [Background technology]

[0002] Conventionally, for example, in excavation machines, which are a type of construction machinery, there are those configured such that a work attachment is detachably attached to an arm that constitutes an excavation device as a front work device. Attachments such as a bucket for excavation work or a crushing device (breaker) for crushing work are attached depending on the type of work. The attachment is connected to the arm via an attachment attachment / detachment device provided at the tip of the arm, and can be attached to or detached from the arm by operating the attachment attachment / detachment device.

[0003] There is a known attachment detachment device that has a fixed hook and a movable hook provided on a predetermined frame, and that is connected to the attachment by engaging each hook with a support pin that the attachment has as an engaged part. In this configuration, a hydraulic cylinder is provided to move the movable hook, and the attachment is attached and detached by extending and retracting the hydraulic cylinder (see, for example, Patent Document 1).

[0004] In addition, the attachment attachment / detachment device of Patent Document 1 is provided with a locking member to prevent the attachment's support pin from coming off the hook, and is configured so that the locking member's anti-detachment function is automatically activated and released when the attachment is attached or detached. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6284445 Summary of the Invention [Problem to be solved by the invention]

[0006] In the attachment detachment device disclosed in Patent Document 1, locking members provided on both the fixed hook and the movable hook are movable between a locked-on position, which prevents the attachment's support pin from coming loose, and a locked-off position, which releases the locking mechanism. The locking member on the movable hook is biased toward the locked-on position by a biasing member. The locking members on the fixed hook and the movable hook are linked to each other via a hydraulic cylinder that moves the movable hook. Therefore, if the biasing member on the movable hook breaks, the locking function provided by the locking member on both the movable hook and the fixed hook will be released. If the hydraulic pressure supply to the hydraulic cylinder is cut off in this situation, the attachment may come loose. Thus, conventional attachment detachment devices leave room for improvement in order to prevent attachment detachment and improve safety.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an attachment mounting / detaching device for construction machinery that can maintain the connected state of the attachment even if the supply of power to the hydraulic cylinder is cut off, thereby ensuring a high level of safety, and a construction machine equipped with the same. [Means for solving the problem]

[0008] The attachment attaching / detaching device for a construction machine according to the present invention is an attachment attaching / detaching device for a construction machine that attaches and detaches a work attachment to and from an arm of a work device, and includes: a first member having a first hook and connected to the arm; a second member having a second hook and rotatably supported by the first member; a first hydraulic cylinder having one end connected to a first support shaft provided on the first member and the other end connected to a second support shaft provided on the second member, and rotating the second member relative to the first member; and a first attachment that is rotatably supported by a third support shaft provided on the first member and positioned above the first hook, and that protrudes into an opening of the first hook. a second hydraulic cylinder that, in conjunction with the operation of the first hydraulic cylinder, moves the first prevention member against the biasing force of the first biasing member so as to retract from the opening of the first hook; a second prevention member that is rotatably supported on a fourth support shaft that is provided on the second member and positioned above the second hook, and is biased by the second biasing member so as to protrude into the opening of the second hook; and a third hydraulic cylinder that, in conjunction with the operation of the first hydraulic cylinder, moves the second prevention member against the second biasing member so as to retract from the opening of the second hook.

[0009] Another aspect of the present invention relates to an attachment mounting / detaching device for a construction machine, wherein in the attachment mounting / detaching device for a construction machine, the second hydraulic cylinder is arranged between the first support shaft and the third support shaft, and the third hydraulic cylinder is arranged between the second support shaft and the fourth support shaft.

[0010] Another aspect of the present invention relates to an attachment attaching / detaching device for a construction machine, wherein the distance between the axis centers of the first support shaft and the second support shaft is shorter than the distance between the axis centers of the third support shaft and the fourth support shaft.

[0011] In addition, another aspect of the present invention is an attachment mounting / detaching device for a construction machine, wherein the distance between the axis centers of a fifth support shaft supporting the second hydraulic cylinder and a sixth support shaft supporting the third hydraulic cylinder is shorter than the distance between the axis centers of the third support shaft and the fourth support shaft.

[0012] In addition, another aspect of the present invention is an attachment attaching / detaching device for a construction machine, in which, when the rod of the first hydraulic cylinder is fully extended, the tip of the second hook is located forward of the fourth support shaft.

[0013] Another aspect of the present invention provides an attachment attaching / detaching device for a construction machine, wherein in the attachment attaching / detaching device for a construction machine, the first hydraulic cylinder is a double-acting hydraulic cylinder, and the second hydraulic cylinder and the third hydraulic cylinder are single-acting hydraulic cylinders, and a branch block is provided inside the first member that branches into a path that supplies pressurized oil to one cylinder chamber of a cylinder tube to retract the rod of the first hydraulic cylinder, and simultaneously supplies pressurized oil to the second hydraulic cylinder and the third hydraulic cylinder to extend their respective rods, and a path that supplies pressurized oil to the other cylinder chamber of the cylinder tube to extend the rod of the first hydraulic cylinder.

[0014] Furthermore, another aspect of the present invention provides an attachment attaching / detaching device for a construction machine, wherein the branch block is arranged above the cylinder tube of the first hydraulic cylinder.

[0015] Another aspect of the present invention provides an attachment attaching / detaching device for a construction machine, wherein the end of each rod of the second hydraulic cylinder and the third hydraulic cylinder has a hemispherical shape, and when the second hydraulic cylinder and the third hydraulic cylinder are contracted, the end of the rod protrudes beyond the end of the cylinder tube.

[0016] The construction machine of the present invention comprises an attachment attachment / detachment device for the construction machine, a traveling device, and a front working device that is provided in front of the traveling device and includes the arm that detachably supports the attachment by the attachment attachment / detachment device. [Effects of the Invention]

[0017] According to the present invention, even if the supply of power to the hydraulic cylinder is cut off, the connection state of the attachment can be maintained, thereby achieving a high level of safety. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a left side view of an excavation machine according to an embodiment of the present invention. FIG. [Figure 2] 1 is a left side view showing a portion of an excavation device according to an embodiment of the present invention. FIG. [Figure 3] 1 is a perspective view showing an attachment attaching / detaching device according to an embodiment of the present invention and a state in which a bucket is detached. FIG. [Figure 4] 1 is a perspective view of an attachment attaching / detaching device according to an embodiment of the present invention. [Figure 5] 1 is a plan view of an attachment attaching / detaching device according to an embodiment of the present invention. [Figure 6] FIG. 2 is a bottom view of the attachment attaching / detaching device according to one embodiment of the present invention. [Figure 7] 1 is a perspective view showing the internal configuration of an attachment attaching / detaching device according to an embodiment of the present invention. [Figure 8] 3 is an enlarged perspective view showing a locking member of an attachment attaching / detaching device according to one embodiment of the present invention. FIG. [Figure 9] FIG. 3 is an explanatory diagram of a second hydraulic cylinder and a third hydraulic cylinder of an attachment attaching / detaching device according to one embodiment of the present invention. [Figure 10] FIG. 3 is an explanatory diagram of a second hydraulic cylinder and a third hydraulic cylinder of an attachment attaching / detaching device according to one embodiment of the present invention. [Figure 11] 1 is a circuit diagram showing a hydraulic circuit configuration for an attachment attaching / detaching device according to an embodiment of the present invention. [Figure 12] 5A to 5C are explanatory diagrams illustrating the operation of the attachment attaching / detaching device according to one embodiment of the present invention. [Figure 13] 5A to 5C are explanatory diagrams illustrating the operation of the attachment attaching / detaching device according to one embodiment of the present invention. [Figure 14] 5A to 5C are explanatory diagrams illustrating the operation of the attachment attaching / detaching device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention relates to an attachment attaching / detaching device for attaching and detaching a work attachment to and from an arm of a front working mechanism of a construction machine, and aims to improve safety by devising a structure for operating a movable hook. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] In this embodiment, an excavator, which is a slewing work vehicle, will be described as an example of the construction machine according to the present invention. However, the construction machine according to the present invention is not limited to excavators, and can be widely applied to other construction machines such as cranes and wheel loaders.

[0021] First, the overall configuration of an excavation machine 1 according to this embodiment will be described using Figure 1. In the following, unless a particular viewing direction is specified, the terms "front side," "rear side," "left and right sides," "flat side" or "upper side," "bottom side" or "lower side" will be used based on the position of an operator seated in the driver's seat of the excavation machine 1.

[0022] As shown in FIG. 1, the excavator 1 includes a traveling device 2 as a self-propelled traveling vehicle body, and an excavator 3 and an earth removal device 4 as working parts attached to the traveling device 2.

[0023] The traveling device 2 is the main part of the excavation machine 1 and has a pair of left and right crawler-type traveling units 5, 5, a machine body frame 6 as a base interposed between the left and right traveling units 5, 5, and a swivel base 7 provided on the machine body frame 6. The swivel base 7 is configured in a substantially circular shape in a plan view, and is provided so as to be swivel in either the left or right direction around an axis extending in the vertical direction by a swivel support part 6a provided on the machine body frame 6.

[0024] A driving section 8 is provided on the swivel 7. A prime mover section 9, which has an engine and the like covered by a bonnet or the like, is provided in the rear half of the swivel 7.

[0025] The driving section 8 is used to drive and operate the traveling device 2, the excavating device 3, and the soil removal device 4, and is provided in a cabin 10 provided on the swivel 7. The cabin 10 has a frame that forms its outer shape, and a plurality of windows made of transparent materials such as glass, and is configured to be roughly box-shaped overall.

[0026] In the driver's section 8, a driver's seat support base is provided on the floor, and a driver's seat 8a is provided on the driver's seat support base. The driver's section 8 is provided with, for example, a pair of left and right travel levers extending upward from the floor, and operation pedals for work arranged on the floor. In addition, in the driver's section 8, an operation panel unit having various operation units such as operation operation levers for operating the working unit (excavation device 3 or earth removal device 4) and switches for switching the operating state of the attachment attaching / detaching device 30 is provided around the driver's seat 8a.

[0027] The base end of the excavator 3 is attached to the left-right center of the front end of the swivel base 7. In addition, the earth removal device 4 is attached to the front side of the machine frame 6. The earth removal device 4 has a support frame 4a extending in the front-rear direction between the left and right running sections 5, 5, and a blade 4b serving as a blade attached to the tip side of the support frame 4a. The earth removal device 4 is mounted so that it can be raised, lowered, and rotated by a cylinder mechanism provided between the support frame 4a and the machine frame 6.

[0028] In the excavator 1 having the above-described configuration, the operator seated in the driver's seat 8a operates the travel lever and / or work control lever as appropriate to perform the desired operation and work. Specifically, for example, operation of the travel lever causes the travel device 2 to travel forward and backward in a straight line or to turn left and right. Furthermore, operation of the work control lever causes the excavator 3 to perform excavation work, or the earth removal device 4 to perform earth removal and / or ground leveling work.

[0029] The excavation device 3 will be described using Figures 1 to 3. The excavation device 3 is a front working device provided in front of the traveling device 2. A support bracket 15 protrudes forward from the center of the left and right of the front end of the swivel base 7, and the base end of the excavation device 3 is attached to the support bracket 15. The excavation device 3 has a boom support bracket 16 as a member that constitutes its base end. The excavation device 3 has the boom support bracket 16 supported by the support bracket 15 on the machine side so that it can rotate with the vertical direction as the rotation axis.

[0030] The excavator 3 is configured to swing left and right relative to the swivel base 7 by a swing cylinder (not shown) located on the right side of the boom support bracket 16. The swing cylinder is provided between the boom support bracket 16 and the swivel base 7.

[0031] The excavator 3 has a boom 17 that forms its base side portion, an arm 18 connected to the tip of the boom 17, and a bucket 20 attached to the tip of the arm 18. The excavator 3 has a boom cylinder 21 that rotates the boom 17, an arm cylinder 22 that rotates the arm 18, and a work tool cylinder 23 that rotates the bucket 20.

[0032] The boom 17 has a shape that is bent like a boomerang in a side view. The base end of the boom 17 is supported by the boom support bracket 16 so as to be rotatable with the left-right direction as the rotation axis. The boom cylinder 21 is disposed on the front side of the boom 17 in an upright state, and is installed between the boom support bracket 16 and a bracket 17a that protrudes inside the bent portion of the boom 17. The boom cylinder 21 extends and retracts, causing the boom 17 to rotate relative to the boom support bracket 16.

[0033] The base end of the arm 18 is connected to the tip of the boom 17 so as to be rotatable with the left-right direction as the rotation axis direction. The arm cylinder 22 is arranged on the upper side (back side) of the boom 17 in an upright state, and is installed between a bracket 17b protruding from the outer side of the bent portion of the boom 17 and the rear end of a rear bracket 18a protruding from the rear end of the arm 18. The arm 18 rotates relative to the boom 17 as the arm cylinder 22 extends and retracts.

[0034] The bucket 20 is connected to the tip of the arm 18 via an attachment attaching / detaching device 30. In other words, the attachment attaching / detaching device 30 is connected to the tip of the arm 18 and is also connected to the bucket 20 in a detachable manner.

[0035] The implement cylinder 23 is disposed on the front side (back side) of the arm 18, which hangs down from the upper end of the boom 17. The implement cylinder 23 has a cylinder 23a and a cylinder rod 23b having a piston at one end and slidably disposed within the cylinder 23a via the piston. One end of the implement cylinder 23, the bottom side (cylinder 23a side), is supported by a front bracket 18b so as to be rotatable with the left-right direction as the rotation axis direction. The front bracket 18b protrudes from the rear end of the arm 18 in front of the rear bracket 18a.

[0036] Meanwhile, the other end of the implement cylinder 23, that is, the rod side (cylinder rod 23b side), is connected to the attachment attaching / detaching device 30 via a first link 26. In addition, the rod side end of the implement cylinder 23 is supported by a portion near the tip of the arm 18 via a second link 27.

[0037] The second link 27 has a pair of left and right link arms 27 a, a base support shaft 27 b installed between one end of the pair of link arms 27 a, and a tip support shaft 27 c installed between the other end of the pair of link arms 27 a. The second link 27 is supported by the base support shaft 27 b so as to be rotatable relative to the arm 18.

[0038] The link arms 27a are formed of arm-shaped (longitudinal) plate-like members with their thickness direction in the left-right direction. One end of each of the pair of link arms 27a is positioned on the left and right outer sides of the left and right side surface portions 18c of the arm 18, and is supported rotatably with respect to the arm 18 by a base-side support shaft 27b that penetrates near the tip end of the arm 18 in the left-right direction.

[0039] The tip end of the cylinder rod 23b of the implement cylinder 23 is rotatably supported on the tip end support shaft 27c. A boss 23c, through which the tip end support shaft 27c passes, is provided at the tip end of the cylinder rod 23b. One end (rear end) of a first link 26 is rotatably supported on the tip end support shaft 27c. One end of the first link 26 branches into left and right ends, and a boss 26a, through which the tip end support shaft 27c passes, is provided at each of the left and right ends. The boss 23c of the cylinder rod 23b is located on the tip end support shaft 27c between the left and right bosses 26a of the first link 26.

[0040] The other end (front end) of the first link 26 is rotatably connected to the attachment attaching / detaching device 30 by a link support shaft 28 that is provided at a predetermined location on the attachment attaching / detaching device 30 with its axial direction running in the left-right direction. The tip of the arm 18 is rotatably connected to the attachment attaching / detaching device 30 by an arm support shaft 29 that is provided at a location on the attachment attaching / detaching device 30 different from the location where the link support shaft 28 is provided and with its axial direction running in the left-right direction.

[0041] In this configuration, extension and contraction of the work tool cylinder 23 causes the first link 26 and the second link 27 to rotate, and the attachment attaching / detaching device 30 rotates about the arm support shaft 29 as a rotation axis. Accordingly, the bucket 20 rotates integrally with the attachment attaching / detaching device 30.

[0042] In the excavator 3 having the above-described configuration, the bucket 20 is detachably attached to the arm 18 as a work attachment by the attachment attaching / detaching device 30. Then, depending on the work content to be performed by the excavator 1, another device such as a grapple or a breaker is attached as the work attachment instead of the bucket 20. In this way, the excavator 3 includes the arm 18 that detachably supports the work attachment by the attachment attaching / detaching device 30, and the arm 18 receives the attachment depending on the work content via the attachment attaching / detaching device 30 provided at the tip of the arm 18.

[0043] The following describes the connection between the attachment attaching / detaching device 30 and the bucket 20. The attachment attaching / detaching device 30 is a device for attaching and detaching the bucket 20 of the excavation machine 1 to and from the arm 18 of the excavation device 3.

[0044] As shown in FIG. 3, the attachment attaching / detaching device 30 is connected to the bucket 20 by engaging a first hook 33 and a second hook 34 with a rear support pin 35 and a front support pin 36 of the bucket 20, respectively.

[0045] The front support pin 36 and the rear support pin 35 are linear rod-shaped members with their axial direction extending in the left-right direction, and are respectively installed between a pair of left and right support ribs 37 that protrude from the back surface 20a of the bucket 20 at a predetermined interval in the left-right direction. The support ribs 37 are plate-shaped protruding pieces whose thickness direction is in the left-right direction.

[0046] The left and right support rib portions 37 support the front support pins 36 and the rear support pins 35 at positions spaced a predetermined distance apart. The left and right support rib portions 37 pass through both ends of the front support pins 36 and the rear support pins 35 and support these support pins in a fixed state. The left and right support rib portions 37 are provided on the base side (upper side in FIG. 3) of the back surface portion 20a of the bucket 20. A plurality of claws 20b are provided at the tip end of the back surface portion 20a of the bucket 20 at predetermined intervals in the left-right direction (see FIG. 2).

[0047] The configuration of the attachment attaching / detaching device 30 will be described with reference to Figures 4 to 13. The attachment attaching / detaching device 30 comprises a fixed frame 31 as a first member having a first hook 33 below it, and a movable frame 32 as a second member having a second hook 34 below it. The attachment attaching / detaching device 30 is configured to be approximately symmetrical overall.

[0048] The fixed frame 31 is a part of the attachment attaching / detaching device 30 that is connected to the arm 18 of the excavation device 3. The fixed frame 31 is supported by an arm support shaft 29 so as to be rotatable relative to the arm 18.

[0049] The arm support shaft 29 is rotatably supported at the tip of the arm 18 while passing through the arm 18 in the left-right direction.

[0050] The fixed frame 31 has a pair of left and right walls: a sidewall frame portion 41 and a rear wall portion 44. The left and right sidewall frame portions 41 are each plate-shaped with a thickness in the left-right direction. In a side view, they have a generally inverted trapezoidal shape with a concave upper edge and a tapered shape from the rear to the front. The rear wall portion 44 is located at the rear ends of the sidewall frame portions 41 and spans between the left and right sidewall frame portions 41. The vertical length of the rear wall portion 44 is shorter than the vertical length of the sidewall frame portions 41, and a rear opening is formed by the rear ends of the left and right sidewall frame portions 41 and the upper end of the rear wall portion 44. A cover plate 51 is provided behind the left and right sidewall frame portions 41 to cover the rear opening and prevent soil and sand from entering the attachment attaching / detaching device 30.

[0051] A hole is formed in the upper rear portion of the sidewall frame portion 41, into which the end portions of the arm support shafts 29 projecting on both the left and right sides at the tip of the arm 18 are inserted and supported. The sidewall frame portion 41 is connected to the arm support shaft 29 so as not to be rotatable relative to the arm, and rotates integrally with the arm support shaft 29 relative to the arm 18. A cylindrical boss portion 41a is provided on the outside of the sidewall frame portion 41 on the right side of the hole into which the arm support shaft 29 is inserted. The fixed frame 31 and the arm support shaft 29 are connected by a connecting bolt 42, a nut 42a, etc. that radially pass through the boss portion 41a and the arm support shaft 29.

[0052] Holes are formed in the upper front portions of the sidewall frame portions 41 to receive and support the left and right ends of the link support shaft 28. The left and right sidewall frame portions 41 are connected to the link support shaft 28 so as not to rotate relative to each other, and rotate integrally with the link support shaft 28 relative to the first link 26. A cylindrical boss portion 41b is provided on the outside of the right sidewall frame portion 41 for the hole that receives the insertion of the link support shaft 28. The sidewall frame portion 41 and the link support shaft 28 are connected by a connecting bolt 43, a nut 43a, and the like that radially penetrate the boss portion 41b and the link support shaft 28.

[0053] First hooks 33 are provided below the side wall frame portions 41. The first hooks 33 are provided as portions having a predetermined thickness in the left-right direction on the left and right inner sides of the side wall frame portions 41. The first hooks 33 have locking portions 46 that extend in a curved shape so as to form a hook shape in a side view.

[0054] An engagement surface 46a having a concave shape with the rear side open in a side view is formed in the locking portion 46. In the locking portion 46, the engagement surface 46a is the portion that comes into contact with the rear support pin 35 of the bucket 20.

[0055] A rear locking member 48 (described later) is provided above the locking portion 46 of the first hook 33 so as to face the engagement surface 46a. The rear locking member 48 is configured to be able to advance and retreat relative to the opening 46b of the locking portion 46.

[0056] Between the hole in the sidewall frame portion 41 that receives the insertion of the arm support shaft 29 and the first hook 33, there are provided holes that receive and support the left and right ends of a bottom-side support shaft 81 (described later). Cylindrical boss portions 41c are provided on the inside of the left and right sidewall frame portions 41 for the holes that receive the insertion of the bottom-side support shaft 81. The sidewall frame portions 41 and the bottom-side support shaft 81 are connected by set screws 81a that pass through the boss portions 41c and screw into screw holes 81b (see FIG. 7) provided in the circumferential surface of the bottom-side support shaft 81.

[0057] The first hook 33 is integrally formed with the left and right side wall frame portions 41, the rear wall portion 44, and the boss portion 41c by casting or the like.

[0058] The movable frame 32 is rotatably mounted on the fixed frame 31, and has a second hook 34 on its lower side that engages with a front support pin 36 of the bucket 20. The movable frame 32 has a pair of left and right wall portions, namely, an attachment frame portion 45 and a front wall portion 47. The second hook 34 is mounted between the left and right attachment frame portions 45.

[0059] The mounting frame portion 45 is a portion that rotatably mounts the movable frame 32 to the fixed frame 31. Each of the left and right mounting frame portions 45 is a plate-like wall portion with the plate thickness direction in the left-right direction, and has a substantially triangular outer shape in side view and a shape that tapers from the bottom to the top. The mounting frame portion 45 forms a frame body made up of a pair of left and right plate-like wall portions.

[0060] A hole through which the link support shaft 28 can be inserted is provided in the upper part of the mounting frame part 45. The mounting frame part 45 is located on the left and right inner sides of the side wall frame part 41, and in a side view, the upper end part along the circumferential shape overlaps with the portion where the hole is formed on the front side of the side wall frame part 41.

[0061] 3, link support shaft 28 passes laterally through boss portion 26b provided at one end of first link 26, the other end of which is connected to second link 27, and its left and right ends are inserted into an upper front hole of side wall frame portion 41 and an upper hole of mounting frame portion 45. By pivotably connecting mounting frame portion 45 to link support shaft 28 fixed to side wall frame portion 41 in this manner, movable frame 32 is provided to be pivotable relative to fixed frame 31.

[0062] The second hooks 34 are provided as portions having a predetermined thickness in the left-right direction on the left and right inner sides of the mounting frame portion 45. The second hooks 34 have locking portions 49 that extend in a curved shape so as to form a hook shape in a side view, similar to the first hooks 33.

[0063] An engagement surface 49a having a concave shape with the front side open in a side view is formed in the locking portion 49. In the locking portion 49, the engagement surface 49a is a portion that comes into contact with the front support pin 36 of the bucket 20.

[0064] A front locking member 58, which will be described later, is provided above the locking portion 49 of the second hook 34 so as to face the engagement surface 49a. The front locking member 58 is configured to be able to advance and retreat with respect to an opening 49b of the second hook 34, which is open facing forward.

[0065] The second hook 34 is integrally formed with the left and right mounting frame portions 45 and the front wall portion 47 by casting or the like.

[0066] Holes are provided between the upper hole of the mounting frame 45 and the second hook 34, for receiving and supporting left and right ends of a rod-side support shaft 82 (described later). Cylindrical bosses 45a are provided on the inside of the left and right mounting frames 45 relative to the holes for receiving the insertion of the rod-side support shaft 82 (see FIG. 5). The mounting frame 45 and the rod-side support shaft 82 are connected by set screws 82a that pass through the bosses 45a and screw into threaded holes 82b (see FIG. 7) provided in the circumferential surface of the rod-side support shaft 82.

[0067] The attachment attaching / detaching device 30 includes a first hydraulic cylinder 55 that rotates the movable frame 32 relative to the fixed frame 31. The first hydraulic cylinder 55 rotates the movable frame 32 back and forth around the axis of the link support shaft 28 by extending and retracting.

[0068] The first hydraulic cylinder 55 is provided in the left-right center of the attachment attaching / detaching device 30, with its extension and retraction direction aligned with the front-rear direction in a plan view. The first hydraulic cylinder 55 has a cylinder tube 61 and a piston rod 62 provided slidably relative to the cylinder tube 61, and extends and retracts due to the sliding movement of the piston rod 62 relative to the cylinder tube 61. A piston 63 that slides within the cylinder tube 61 is provided on one end of the piston rod 62 located within the cylinder tube 61 (see FIG. 11).

[0069] 11, the first hydraulic cylinder 55 is a double-acting hydraulic cylinder, and the internal space of the cylinder tube 61 is divided by the piston 63 into a bottom-side chamber 61a, which is the space on the cylinder tube 61 side (bottom side), and a rod-side chamber 61b, which is the space on the piston rod 62 side (rod side). The first hydraulic cylinder 55 expands and contracts by moving the piston rod 62 relative to the cylinder tube 61 by supplying and discharging pressure oil to and from the bottom-side chamber 61a and the rod-side chamber 61b.

[0070] The support structure of the first hydraulic cylinder 55 will now be described. The first hydraulic cylinder 55 is provided between the left and right side wall frame portions 41 of the fixed frame 31, and between the left and right mounting frame portions 45 of the movable frame 32. The first hydraulic cylinder 55 is provided with its piston rod 62 facing forward, with the piston rod 62 side supported by the movable frame 32 and the cylinder tube 61 side supported by the fixed frame 31. In other words, the first hydraulic cylinder 55 connects the movable frame 32 and the fixed frame 31 to each other.

[0071] The rear side of the first hydraulic cylinder 55 is rotatably supported by a bottom-side support shaft 81, which is a first support shaft. The bottom-side support shaft 81 is installed between the left and right side wall frame portions 41, with the left-right direction as the axial direction. A substantially cylindrical boss portion 61d having a hole through which the bottom-side support shaft 81 passes is provided at the rear end of the cylinder tube 61. The boss portion 61d is located at the center of the bottom-side support shaft 81 in the axial direction, and is supported so as to be rotatable relative to the bottom-side support shaft 81. The left and right ends of the bottom-side support shaft 81 are supported in a state where they are inserted into holes provided in the left and right side wall frame portions 41 of the fixed frame 31, respectively.

[0072] A branch block 61c is provided above the first hydraulic cylinder 55 (see FIGS. 6 and 8). Furthermore, as shown in FIG. 4, the branch block 61c is covered from above with a cover plate 52. For convenience, in the plan view of FIG. 5, the front support pin 36, the rear support pin 35, and the cover plate 52 are indicated by dashed lines.

[0073] The bottom-side support shaft 81 is fixed to a hole formed in the side wall frame portion 41 by a set screw 81a or the like that is threaded through the boss portion 41c and along the radial direction of the bottom-side support shaft 81, thereby being supported so as not to rotate relative to the fixed frame 31. On the other hand, the cylinder tube 61 is supported so as to be rotatable relative to the bottom-side support shaft 81.

[0074] The front side of the first hydraulic cylinder 55 is rotatably supported by a rod-side support shaft 82, which is a second support shaft. The rod-side support shaft 82 is installed between the left and right mounting frame portions 45 with the left-right direction as the axial direction. That is, the rod-side support shaft 82 is installed parallel to the bottom-side support shaft 81. A substantially cylindrical boss portion 62a having a hole through which the rod-side support shaft 82 passes is provided at the tip of the piston rod 62. The boss portion 62a is located in the center of the rod-side support shaft 82 in the axial direction and is supported so as to be rotatable relative to the rod-side support shaft 82. The left and right ends of the rod-side support shaft 82 are supported in a state where they are inserted into holes provided in the left and right mounting frame portions 45 of the movable frame 32, respectively.

[0075] The rod-side support shaft 82 is fixed to a hole formed in the mounting frame portion 45 by a set screw 82a or the like that passes through the boss portion 45a and is screwed along the radial direction of the rod-side support shaft 82. This supports the rod-side support shaft 82 so as not to rotate relative to the movable frame 32. The piston rod 62 is supported so as to be rotatable relative to the rod-side support shaft 82 that is inserted into the hole of the boss portion 62a.

[0076] According to the support configuration of the first hydraulic cylinder 55 as described above, as the first hydraulic cylinder 55 extends and retracts, the bottom-side support shaft 81 rotates the first hydraulic cylinder 55, and the rod-side support shaft 82 moves integrally with the piston rod 62 which moves relative to the cylinder tube 61. This causes the movable frame 32 to rotate about the axis of the link support shaft 28 relative to the fixed frame 31 (see FIG. 13).

[0077] The structure for rotating the rear locking member 48 and the front locking member 58 will now be described.

[0078] The attachment attaching / detaching device 30 is provided, on the fixed frame 31, with a rear locking member 48 as a first retention member, a second hydraulic cylinder 56, and a lock spring 83a as a first biasing member. The attachment attaching / detaching device 30 is also provided, on the movable frame 32, with a front locking member 58 as a second retention member, a third hydraulic cylinder 57, and a lock spring 83b as a second biasing member. The rear locking member 48, second hydraulic cylinder 56, and locking spring 83a on the fixed frame 31 side and the front locking member 58, third hydraulic cylinder 57, and locking spring 83b on the movable frame side are arranged in approximate mirror symmetry in the front-to-rear direction of the attachment attaching / detaching device 30.

[0079] The components that make up the rear locking member 48 and the front locking member 58 are identical in shape. The second hydraulic cylinder 56 and the third hydraulic cylinder 57 are single-acting cylinders with the same specifications. Furthermore, the lock springs 83a and 83b are torsion coil springs with the same specifications. Details of each component are explained below, with the same reference numerals used to describe common components. Furthermore, unless otherwise specified, the lock springs 83a and 83b will be described as the lock spring 83.

[0080] The rear locking member 48 is rotatably provided on the fixed frame 31, and is a member that restricts the rear support pin 35 engaged with the first hook 33 from disengaging from the first hook 33. The rear locking member 48 is rotatably supported with respect to the fixed frame 31 by a rear support shaft 91 serving as a third support shaft that is installed between the left and right side wall frame portions 41 of the fixed frame 31 with its axial direction extending in the left-right direction.

[0081] The rear support shaft 91 is disposed above the first hook 33. The rear support shaft 91 is provided parallel to the bottom-side support shaft 81 with both ends supported at predetermined positions on the left and right side wall frame portions 41. For this reason, holes that support both ends of the rear support shaft 91 are formed in the left and right side wall frame portions 41.

[0082] The front locking member 58 is a member that prevents the front support pin 36 engaged with the second hook 34 from disengaging from the second hook 34 in the movable frame 32. The front locking member 58 is rotatably supported with respect to the fixed frame 31 by a front support shaft 92 serving as a fourth support shaft that is installed between the left and right mounting frame portions 45 in the movable frame 32 with its axial direction extending in the left-right direction.

[0083] The front support shaft 92 is disposed above the second hook 34. The front support shaft 92 is provided parallel to the rod-side support shaft 82 by having both ends supported at predetermined positions on the left and right mounting frame portions 45. For this reason, holes that support both ends of the front support shaft 92 are formed in the left and right mounting frame portions 45.

[0084] The rear locking member 48 and the front locking member 58 each have a locking claw 93, which is a portion having a predetermined dimension in the left-right direction, and left and right support portions 94, which are portions supported by the rear support shaft 91 or the front support shaft 92. The locking claw 93 has a tapered shape in side view. One of the left and right support portions 94 (the right side) is provided with an abutment portion 87 along the axial direction of the support shaft that is pressed by the piston rod 77 of the second hydraulic cylinder 56 or the third hydraulic cylinder 57, which will be described later. Between the left and right support portions 94 is a recess 95, with the support portion 94 as the side wall and the base end of the locking claw 93 as the bottom surface.

[0085] The lock spring 83 is disposed in a recess 95 between the left and right support portions 94. The lock spring 83 has extensions 84, 85 on both ends of a coil-shaped portion. The lock spring 83 exerts a force that presses the lock claw portion 93 downward by applying a biasing force in a direction that separates the extensions 84, 85 from each other. The lock spring 83 is disposed with its coil-shaped portion passing through the rear support shaft 91 or the front support shaft 92 that is located between the left and right support portions 94.

[0086] The contact portion 87 is a portion that receives an external force that rotates the rear locking member 48 or the front locking member against the biasing force of the lock spring 83. The contact portion 87 protrudes from one of the left and right support portions 94, forming an angle of approximately 90 degrees with the direction in which the locking claw portion 93 extends.

[0087] The rear locking member 48 has a hole in each support portion 94 through which the rear support shaft 91 passes. Each support portion 94 is fixed to the rear support shaft 91 by welding or the like, and the rear locking member 48 is configured as an integrated rotating body that rotates relative to the rear support shaft 91.

[0088] Regarding the rotational movement of the rear locking member 48 around the rear support shaft 91, a rotational position where the locking claw portion 93 protrudes from the underside of the side wall frame portion 41 into the opening 46b of the first hook 33 in a side view is a locked position where the rear support pin 35 engaged with the first hook 33 is prevented from disengaging from the first hook 33 (see FIG. 13). That is, the rear locking member 48 rotates within a range from an unlocked position where it is hidden within the outline of the fixed frame 31 in a side view, to a locked position, as shown in the drawings, etc. The rear locking member 48 moves from the unlocked position to the locked position by rotating leftward (counterclockwise) in a left side view shown in FIG. 13.

[0089] The lock spring 83a is disposed in a recess 95 between the left and right support portions 94 of the rear locking member 48. The lock spring 83a is a biasing member that biases the rear locking member 48 in a rotation direction toward a position (locked position) that restricts the release of the rear support pin 35 from the first hook 33. In other words, the lock spring 83a biases the rear locking member 48 in a rotation direction from the unlocked position to the locked position when the rear locking member 48 rotates about the rear support shaft 91. In other words, the lock spring 83a biases the rear locking member 48 in a counterclockwise rotation direction when viewed from the left side.

[0090] The lock spring 83a has one extension 84 located on the left or right outer side of the coiled portion engaged with the rear wall 44 of the fixed frame 31, and the other extension 85 located on the left or right inner side of the coiled portion engaged with the lock claw 93. In other words, the rear locking member 48 is urged by the lock spring 83a in the rotation direction around the axis of the rear support shaft 91 relative to the first hook 33 from the unlocked position to the locked position.

[0091] When the abutment portion 87 of the rear locking member 48 is pressed by the piston rod 77 of the second hydraulic cylinder 56 and rotates, the rear locking member 48 rotates in the direction opposite to the direction in which it assumes the locked position.

[0092] The second hydraulic cylinder 56 is provided on the fixed frame 31 and rotates the rear locking member 48 about the axis of the rear support shaft 91 via the abutment portion 87 by expanding and contracting.

[0093] The front locking member 58 is provided so as to be rotatable integrally with the front support shaft 92, and like the rear locking member 48, has a locking claw portion 93 which is a portion having a predetermined dimension in the left-right direction, and left and right support portions 94 which are portions supported by the front support shaft 92, and a recess 95 in which a lock spring 83b is disposed is provided between the left and right support portions 94. In addition, one of the left and right support portions 94 (the left side) is provided with an abutment portion 87 which is pressed by a piston rod 77 of a third hydraulic cylinder 57 (described later) along the axial direction of the front support shaft 92.

[0094] The lock spring 83b has one extension 84 located on the left or right outer side of its coiled portion engaged with the front wall 47 of the movable frame 32, and the other extension 85 located on the left or right inner side of its coiled portion engaged with the lock claw 93. In other words, the lock spring 83b urges the front locking member 58 in a rotational direction around the axis of the front support shaft 92 relative to the second hook 34 from the unlocked position to the locked position. In other words, the lock spring 83b urges the front locking member 58 in a clockwise rotational direction when viewed from the left side.

[0095] Regarding the rotational movement of the front locking member 58 around the front support shaft 92, a rotational position where the locking claw portion 93 protrudes from the underside of the mounting frame portion 45 into the opening 49b of the second hook 34 in a side view is a locked position where the front support pin 36 engaged with the second hook 34 is prevented from disengaging from the second hook 34 (see FIG. 13). That is, as shown in FIGS. 12 and 13, the front locking member 58 rotates within a range from an unlocked position where it is hidden within the outline of the movable frame 32 in a side view to a locked position. The front locking member 58 moves from the unlocked position to the locked position by rotating leftward (counterclockwise) in a left side view.

[0096] The third hydraulic cylinder 57 is provided on the movable frame 32 and rotates the front locking member 58 about the axis of the front support shaft 92 via the abutment portion 87 by expanding and contracting.

[0097] As shown in Figures 7 and 12, the second hydraulic cylinder 56 and the third hydraulic cylinder 57 are hydraulic cylinders smaller than the first hydraulic cylinder 55, and are provided so that their extension and contraction directions are in the front-to-rear direction in a plan view. The second hydraulic cylinder 56 and the third hydraulic cylinder 57 each have a cylinder tube 76 and a piston rod 77 provided slidably relative to the cylinder tube 76, and are extended and contracted by the sliding movement of the piston rod 77 relative to the cylinder tube 76. A piston 78 that slides within the cylinder tube 76 is connected to one end of the piston rod 77, and the other end forms an abutment end 77a that abuts against the abutment portions 87 of the rear locking member 48 and the front locking member 58, respectively.

[0098] As shown in FIG. 11 , the piston 78 defines a bottom-side chamber 76a, which is a space on the bottom side of the cylinder tube 76, within the internal space of the cylinder tube 76. As shown in FIGS. 9 and 10 , the rod-side end of the cylinder tube 76 is open so that the piston rod 77 can be movably housed within the cylinder tube 76 and the end of the piston rod 77 opposite the end connected to the piston 78 can protrude from the cylinder tube 76. The end of the piston rod 77 protruding from the cylinder tube 76 has a hemispherical shape and forms a contact end 77a that abuts against the contact portions 87 of the rear locking member 48 and the front locking member 58. By supplying and discharging pressure oil to and from the bottom-side chamber 76a, the piston rod 77 moves between a contracted state shown in the perspective view of FIG. 9A and the cross-sectional view of FIG. 9B and an extended state shown in the perspective view of FIG. 10A and the cross-sectional view of FIG. 10B. When the piston rod 77 is retracted, the hemispherical abutment end 77a protrudes outward from the rod-side end of the cylinder tube 76. Therefore, for example, when operating the bucket 20 to perform excavation work, it is possible to prevent soil and sand and the like from entering between the inside of the cylinder tube 76 and the sliding surface of the piston rod 77. Furthermore, in this embodiment, a seal member 79 is provided at the rod-side end of the cylinder tube 76, which further prevents soil and other foreign matter from entering the cylinder tube 76.

[0099] One ends of branch pipes 80a, 80b branching off from the rod-side hydraulic pipe 66 are connected to the second hydraulic cylinder 56 and the third hydraulic cylinder 57 so as to communicate with the bottom-side chamber 76a. A connection port 76c for receiving connection of the branch pipe 80a protrudes from the cylinder tube 76. The branch pipes 80a, 80b are formed of hoses or the like. The other ends of the branch pipes 80a, 80b are connected to and communicate with the rod-side hydraulic pipe 66.

[0100] Branching of the rod-side hydraulic piping 66 into branch piping 80a, 80b is achieved by a branch block 61c. The branch block 61c, together with the check valve 65a shown in FIG. 11, is arranged above the cylinder tube 61 of the first hydraulic cylinder 55, and is a member that receives connection of the bottom-side hydraulic piping 65 and the rod-side hydraulic piping 66. The branch block 61c is connected to the branch piping 80a, 80b that supplies pressure oil to the second hydraulic cylinder 56 and the third hydraulic cylinder 57. The branch block 61c branches the pressure oil flowing through the rod-side hydraulic piping 66 into the branch piping 80a, 80b. That is, the branch block 61c branches into a path that supplies pressurized oil to one cylinder chamber (rod side chamber 61b) of the cylinder tube 61 to contract the piston rod 62 of the first hydraulic cylinder 55, and at the same time supplies pressurized oil to the second hydraulic cylinder 56 and the third hydraulic cylinder 57 to extend their respective piston rods 77, and a path that supplies pressurized oil to the other cylinder chamber (bottom side chamber 61a) of the cylinder tube 61 to extend the piston rod 62 of the first hydraulic cylinder 55.

[0101] Furthermore, when the hydraulic pressure supplied to the bottom-side chamber 76a through the branch pipe 80 exceeds a predetermined value, the second hydraulic cylinder 56 and the third hydraulic cylinder 57 extend, causing the piston rod 77 to further protrude from the cylinder tube 76. The piston rod 77 may return by either a load-return mechanism or a spring-return mechanism. For example, in the load-return mechanism, when the hydraulic pressure in the bottom-side chamber 76a falls below a predetermined value, the rear locking member 48 and the front locking member 58 are rotated by the biasing force of the lock spring 83, and the abutment portion 87 rotates, exerting an external force on the abutment end 77a of the piston rod 77, thereby moving the piston rod 77 in a retracting direction. In the spring-return mechanism, a coil spring is provided on the back side of the piston 78 in the cylinder tube 76. When the hydraulic pressure in the bottom-side chamber 76a falls below a predetermined value, the elastic force of the coil spring moves the piston rod 77 in a retracting direction via the piston 78.

[0102] The positional relationship between the first hydraulic cylinder 55, the second hydraulic cylinder 56, and the third hydraulic cylinder 57 in the attachment attaching / detaching device 30 will be described.

[0103] In the attachment attaching / detaching device 30, the first hydraulic cylinder 55 is provided between the left and right side wall frame portions 41 and between the left and right mounting frame portions 45. In this embodiment, the first hydraulic cylinder 55 is disposed in the center of the left and right side wall frame portions 41 in the left-right direction.

[0104] In this configuration, the second hydraulic cylinder 56 is disposed below the first hydraulic cylinder 55 on the side of one of the left and right sidewall frame portions 41 via a second hydraulic cylinder support shaft 98 serving as a fifth support shaft. The second hydraulic cylinder support shaft 98 is located between the bottom-side support shaft 81, which is the first support shaft, and the rear support shaft 91, which is the third support shaft, in the up-down direction, and is provided parallel to the bottom-side support shaft 81 and the rear support shaft 91. In this embodiment, the second hydraulic cylinder 56 is disposed between the first hydraulic cylinder 55 and the left sidewall frame portion 41 of the pair of left and right sidewall frame portions 41 in the left-right direction.

[0105] The third hydraulic cylinder 57 is disposed below the first hydraulic cylinder 55 on the side of one of the left and right mounting frame portions 45 via a third hydraulic cylinder support shaft 99 serving as a sixth support shaft. The third hydraulic cylinder support shaft 99 is located between the rod side support shaft 82 serving as the second support shaft and the front support shaft 92 serving as the fourth support shaft in the up-down direction, and is provided parallel to the rod side support shaft 82 and the front support shaft 92. In this embodiment, the third hydraulic cylinder 57 is disposed between the first hydraulic cylinder 55 and the left side wall frame portion 41 of the pair of left and right mounting frame portions 45 in the left-right direction.

[0106] The hydraulic circuits that operate the first hydraulic cylinder 55, the second hydraulic cylinder 56, and the third hydraulic cylinder 57 will be further described.

[0107] 11, one end of bottom-side hydraulic piping 65, which is formed of a hose or the like, is connected to the first hydraulic cylinder 55 so as to communicate with the bottom-side chamber 61a. The other end of the bottom-side hydraulic piping 65 is connected to a bottom-side cylinder port (A) of an electromagnetic switching valve 67 for switching the flow path. The bottom-side hydraulic piping 65 is provided with a check valve 65a.

[0108] Furthermore, one end of a rod-side hydraulic pipe 66 formed of a hose or the like is connected to the first hydraulic cylinder 55 so as to communicate with the rod-side chamber 61b. The other end of the rod-side hydraulic pipe 66 is connected to a rod-side cylinder port (B) of an electromagnetic switching valve 67.

[0109] One end of a supply pipe 68 is connected to a supply port (P) of the electromagnetic directional control valve 67. The other end of the supply pipe 68 opens toward an oil tank 69 provided on the traveling device 2 side. A hydraulic pump 64 is provided on the supply pipe 68, and operation of the hydraulic pump 64 supplies hydraulic oil in the oil tank 69 to the first hydraulic cylinder 55 via the electromagnetic directional control valve 67. One end of a discharge pipe 70, which is a return pipe to the oil tank 69, is connected to a discharge port (T) of the electromagnetic directional control valve 67. The other end of the discharge pipe 70 opens toward the oil tank 69. A relief valve 71 is interposed between the supply pipe 68 and the discharge pipe 70 to control the pressure of the hydraulic oil delivered from the hydraulic pump 64.

[0110] The operation of attaching and detaching bucket 20 using attachment attaching and detaching device 30 will be described with reference to Figures 12 and 13. Note that, for the sake of simplicity, some components of attachment attaching and detaching device 30 are not shown in these figures. In addition, in these figures, the external shape of attachment attaching and detaching device 30 is shown by a dashed line, and rear support pin 35 and front support pin 36 of bucket 20 are shown by a dashed double-dashed line.

[0111] In the following description, the state in which the bucket 20 is connected and supported on the excavator 3 and the attachment attaching / detaching device 30 is engaged with the bucket 20 will be referred to as the "engaged state." In the attached attachment attaching / detaching device 30 in the engaged state, the first hydraulic cylinder 55 is extended, and the second hook 34 of the movable frame 32 is farthest from the first hook 33 of the fixed frame 31. At this time, as shown in FIG. 13 , the distance L1 between the axis centers of the bottom side support shaft 81 and the rod side support shaft 82 is shorter than the distance M1 between the axis centers of the rear support shaft 91 and the front support shaft 92. In addition, the distance N1 between the axis centers of the second hydraulic cylinder support shaft 98 and the third hydraulic cylinder support shaft 99 is shorter than the distance M1 between the axis centers of the rear support shaft 91 and the front support shaft 92.

[0112] Furthermore, the state before the bucket 20 is attached to the excavator 3 or after it is detached, in which the attachment attaching / detaching device 30 has released its engagement with the bucket 20, is referred to as the "disengaged state." With the attachment attaching / detaching device 30 in the disengaged state, the first hydraulic cylinder 55 is retracted, and the second hook 34 of the movable frame 32 is closest to the first hook 33 of the fixed frame 31. At this time, as shown in FIG. 12 , the distance L2 between the axis centers of the bottom-side support shaft 81 and the rod-side support shaft 82 is shorter than the distance M2 between the axis centers of the rear support shaft 91 and the front support shaft 92. Furthermore, the distance N2 between the axis centers of the second hydraulic cylinder support shaft 98 and the third hydraulic cylinder support shaft 99 is shorter than the distance M1 between the axis centers of the rear support shaft 91 and the front support shaft 92.

[0113] That is, the attachment attaching / detaching device 30 is in an engaged state when the first hook 33 and the second hook 34 are engaged with the rear support pin 35 and the front support pin 36 of the bucket 20, respectively, and is in a disengaged state when the first hook 33 and the second hook 34 are disengaged from their respective support pins (disengaged state). In either the engaged state or the disengaged state, the following relationship holds in the fore-and-aft direction of the attachment attaching / detaching device 30: distance between the axis centers of the rear support shaft 91 and the front support shaft 92 > distance between the axis centers of the bottom side support shaft 81 and the rod side support shaft 82 > distance between the axis centers of the second hydraulic cylinder support shaft 98 and the third hydraulic cylinder support shaft 99. The length of the distance between the axes of the second hydraulic cylinder support shaft 98 and the third hydraulic cylinder support shaft 99 relative to the distance between the axes of the rear support shaft 91 and the front support shaft 92 may be changed depending on the size of the first hydraulic cylinder 55 and / or where the support shafts (98, 99) are located on the second hydraulic cylinder 56 and the third hydraulic cylinder 57.

[0114] The attachment and detachment work of the bucket 20 using the attachment detachment device 30 is performed by operating the boom 17 and arm 18 of the excavation device 3 by operating an operating unit etc. provided in the cabin 10 with the bucket 20 placed on the ground etc. with the front support pin 36 and rear support pin 35 side facing up, and moving the attachment detachment device 30.

[0115] In other words, when attaching the bucket 20 to the attachment detachment device 30, the attachment detachment device 30 is brought closer to the bucket 20, which is placed on the ground or the like, by operating an operating unit or the like provided in the cabin 10, and the attachment detachment device 30 is brought into an engaged state while engaging with the bucket 20 in a predetermined procedure, thereby attaching the bucket 20 to the attachment detachment device 30.

[0116] On the other hand, when removing the bucket 20 from the attachment detachment device 30, the bucket 20 is placed on the ground or the like by operating an operating unit or the like provided in the cabin 10, and the attachment detachment device 30 is brought into a disengaged state by disengaging the attachment detachment device 30 from the bucket 20 in a predetermined procedure, and the attachment detachment device 30 is then separated from the bucket 20 by operating an operating unit or the like provided in the cabin 10, thereby removing the bucket 20 from the attachment detachment device 30.

[0117] The operation of the attachment attaching / detaching device 30 when attaching the bucket 20 to the attachment attaching / detaching device 30 (when attaching the bucket) will be described. When the attachment attaching / detaching device 30 is in a disengaged state and no hydraulic pressure is supplied to the attachment attaching / detaching device 30, the first hydraulic cylinder 55, the second hydraulic cylinder 56, and the third hydraulic cylinder 57 are in a contracted state. In other words, the rear locking member 48 on the first hook 33 side and the front locking member 58 on the second hook 34 side are in a locked position biased by the lock spring 83 so that the tips of the locking claws 93 face downward.

[0118] When attaching the bucket 20, the attachment attaching / detaching device 30 in a disengaged state is moved closer to the bucket 20 by operating an operating unit or the like provided inside the cabin 10 (see FIGS. 3 and 13). With the attachment attaching / detaching device 30 in a disengaged state, the distance between the tips of the engaging portions 46, 49 of the first hook 33 and the second hook 34 is shorter than the distance between the rear support pin 35 and the front support pin 36 of the bucket 20.

[0119] Next, an operation command from the operating unit inside the cabin 10 operates the hydraulic circuit of the attachment attaching / detaching device 30, moving the rear locking member 48 and the front locking member 58 to the unlocked position and enabling the first hook 33 and the second hook 34 to receive the rear support pin 35 and the front support pin 36. At this time, the solenoid directional control valve 67 in the hydraulic circuit is in a flow path switching state, connecting the supply port (P) to the rod-side cylinder port (B) and connecting the discharge port (T) to the bottom-side cylinder port (A). Therefore, operation of the hydraulic pump 64 causes pressure oil to be supplied from the supply piping 68 via the solenoid directional control valve 67 to the rod-side hydraulic piping 66 and the rod-side chamber 61b of the first hydraulic cylinder 55, and also to the bottom-side chambers 76a of the second hydraulic cylinder 56 and the third hydraulic cylinder 57 via branch piping 80, 80a, 80b branching from the rod-side hydraulic piping 66.

[0120] That is, in the first hydraulic cylinder 55, the piston rod 62 is maintained in a contracted state, whereas in the second hydraulic cylinder 56 and the third hydraulic cylinder 57, pressure oil is supplied to each bottom-side chamber 76a, and the piston rod 77 is extended. As a result, a pressing force is applied to the abutment portion 87 of the rear locking member 48, causing the abutment portion 87 and the locking claw portion 93 to rotate together with the rear support shaft 91, and the locking claw portion 93 is accommodated above the first hook 33. Similarly, a pressing force is applied to the abutment portion 87 of the front locking member 58, causing the abutment portion 87 and the locking claw portion 93 to rotate together with the front support shaft 92, and the locking claw portion 93 is accommodated above the second hook 34. That is, the rear locking member 48 and the front locking member 58 move to the unlocked position.

[0121] As the rear locking member 48 and the front locking member 58 move to the unlocked position, the rear support pin 35 can be received in the locking portion 46 of the first hook 33, and the front support pin 36 can be received in the locking portion 49 of the second hook 34.

[0122] Once the rear locking member 48 and the front locking member 58 have moved to the unlocked position, first, the rear support pin 35 is engaged with the first hook 33. Next, with the rear support pin 35 engaged with the first hook 33, the first hydraulic cylinder 55 is extended. That is, by operation of the hydraulic pump 64, pressure oil is supplied from the supply piping 68 through the solenoid directional control valve 67 to the bottom-side chamber 61a by the bottom-side hydraulic piping 65, and as shown in FIG. 13, the first hydraulic cylinder 55 is extended. Here, in the hydraulic circuit shown in FIG. 11, the solenoid directional control valve 67 is in a flow path switching state, so that the supply port (P) communicates with the bottom-side cylinder port (A) and the discharge port (T) communicates with the rod-side cylinder port (B).

[0123] As the first hydraulic cylinder 55 extends, the movable frame 32 rotates forward about the link support shaft 28, and the locking portion 46 of the second hook 34 engages with the front support pin 36 (see FIG. 13). Here, with respect to the rotation direction of the movable frame 32, the direction in which the second hook 34 engages with the front support pin 36 is clockwise when viewed from the left side, and the direction in which the second hook 34 releases the engagement with the front support pin 36 is counterclockwise when viewed from the left side.

[0124] Furthermore, during the extension operation of the first hydraulic cylinder 55, hydraulic oil is discharged from the rod-side chamber 61b to the rod-side hydraulic piping 66 in accordance with the movement of the piston 63. Thereafter, hydraulic oil in the bottom-side chambers 76a of the second hydraulic cylinder 56 and the third hydraulic cylinder 57 is also discharged from the branch piping 80a, 80b, 80b to the rod-side hydraulic piping 66. Here, the contraction operation of the second hydraulic cylinder 56 and the third hydraulic cylinder 57 is performed after the extension operation of the first hydraulic cylinder 55. This is because the force that contracts the second hydraulic cylinder 56 and the third hydraulic cylinder 57 is sufficiently smaller than the force of the hydraulic pump 64 that extends the first hydraulic cylinder 55, and therefore the discharge of hydraulic oil from the bottom-side chambers 76a of the second hydraulic cylinder 56 and the third hydraulic cylinder 57 occurs later than the discharge of hydraulic oil from the rod-side chamber 61b of the first hydraulic cylinder 55.

[0125] When further extension of the first hydraulic cylinder 55 is restricted by the engagement of the second hook 34 with the front support pin 36, the pressure in the path from the hydraulic pump 64 to the bottom-side chamber 61a of the first hydraulic cylinder 55 is maintained at a predetermined value by the action of the relief valve 71. In other words, the force that separates the first hook 33 and the second hook 34, generated by the extension operation of the first hydraulic cylinder 55, causes the rear support pin 35 to engage with the engagement surface 46a of the first hook 33, and the front support pin 36 to engage with the engagement surface 49a of the second hook 34.

[0126] As shown in FIG. 13, when the first hook 33 engages with the rear support pin 35 and the second hook 34 engages with the front support pin 36 and the extension of the first hydraulic cylinder 55 stops, the second hydraulic cylinder 56 and the third hydraulic cylinder 57 automatically retract the piston rod 77 into the cylinder tube 76 to shorten it.

[0127] When the second hydraulic cylinder 56 contracts and no longer applies a pressing force to the abutment portion 87, the biasing force of the lock spring 83a acts on the rear locking member 48, causing the rear locking member 48 to rotate together with the rear support shaft 91. As a result, the rear locking member 48 moves (rotates) from the unlocked position to the locked position. Similarly, when the third hydraulic cylinder 57 contracts and no longer applies a pressing force to the abutment portion 87, the biasing force of the lock spring 83 acts on the front locking member 58, causing the front locking member 58 to rotate together with the front support shaft 92. As a result, the front locking member 58 moves (rotates) from the unlocked position to the locked position. In other words, a locked state is obtained in which the rear support pin 35, which is engaged with the first hook 33, is prevented from disengaging from the first hook 33 by the rear locking member 48, and a locked state is obtained in which the front support pin 36, which is engaged with the second hook 34, is prevented from disengaging from the second hook 34 by the front locking member 58.

[0128] In this way, the attachment detachment device 30 is engaged, and the attachment state of the bucket 20 to the attachment detachment device 30 is such that the second hook 34 and the first hook 33 are engaged with the front and rear support pins (35, 36), respectively, and a locked state is obtained by the front and rear locking members (58, 48) at the engagement portions of each hook (33, 34) with the support pins (35, 36).

[0129] The locked state by the front and rear locking members (58, 48) is achieved by the biasing force of the lock spring 83 causing the front and rear locking members (58, 48) to protrude into the respective openings (49b, 46b) of the second hook 34 and the first hook 33.

[0130] Next, we will explain the operation of the attachment attaching / detaching device 30 when removing the bucket 20 from the attachment attaching / detaching device 30 (when removing the bucket). The operation of the attachment attaching / detaching device 30 when removing the bucket is basically the reverse of the operation when attaching the bucket.

[0131] As shown in Figure 13, from a state in which the attachment detachment device 30 is engaged and the bucket 20 is attached, the second hydraulic cylinder 56 and the third hydraulic cylinder 57 are extended while the first hydraulic cylinder 55 is retracted.

[0132] 11, operation of the hydraulic pump 64 supplies pressure oil from the supply piping 68 via the solenoid directional control valve 67 to the rod-side hydraulic piping 66 and branch piping 80 to the bottom-side chamber 76a, causing the second hydraulic cylinder 56 and the third hydraulic cylinder 57 to extend. Also, hydraulic pressure is supplied to the rod-side chamber 61b of the first hydraulic cylinder 55, causing the first hydraulic cylinder 55 to retract. Here, the solenoid directional control valve 67 is in a flow path switching state, connecting the supply port (P) to the rod-side cylinder port (B) and connecting the discharge port (T) to the bottom-side cylinder port (A).

[0133] When the second hydraulic cylinder 56 extends, a pressing force is applied from the piston rod 77 to the abutment portion 87, causing the rear locking member 48 to rotate together with the rear support shaft 91 against the biasing force of the lock spring 83a. As a result, the rear locking member 48 moves (rotates) from the locked position to the unlocked position. Similarly, when the third hydraulic cylinder 57 extends, a pressing force is applied from the piston rod 77 to the abutment portion 87, causing the front locking member 58 to rotate together with the front support shaft 92 against the biasing force of the lock spring 83a. As a result, the front locking member 58 moves (rotates) from the locked position to the unlocked position. In other words, the rear locking member 48 and the front locking member 58 can achieve an unlocked state in which the rear support pin 35, which is engaged with the first hook 33, can be disengaged from the first hook 33, and an unlocked state in which the front support pin 36, which is engaged with the second hook 34, can be disengaged from the second hook 34.

[0134] According to the hydraulic circuit configuration (see FIG. 11 ) of the excavator 1, the retraction operation of the first hydraulic cylinder 55 and the extension operation of the second hydraulic cylinder 56 and the third hydraulic cylinder 57 are executed simultaneously in response to a command to switch the flow path of the solenoid controlled directional control valve 67 from the operation unit inside the cabin 10, but there is a time lag between the start timing of these two operations. The second hydraulic cylinder 56 and the third hydraulic cylinder 57 are hydraulic cylinders that are sufficiently smaller than the first hydraulic cylinder 55. Therefore, when pressure oil is supplied from the rod-side hydraulic piping 66 to the rod-side chamber 61 b ​​of the first hydraulic cylinder 55, the pressure oil supplied to the second hydraulic cylinder 56 and the third hydraulic cylinder 57 by the branch piping 80, 80 a, 80 b branching from the rod-side hydraulic piping 66 causes the second hydraulic cylinder 56 and the third hydraulic cylinder 57 to extend before the retraction operation of the first hydraulic cylinder 55.

[0135] When the first hydraulic cylinder 55 is contracted, the movable frame 32 rotates rearward about the link support shaft 28, and the engagement of the locking portion 46 of the second hook 34 with the front support pin 36 is released.

[0136] In this way, the attachment attaching / detaching device 30 is put into a disengaged state. Then, the boom 17 and / or arm 18 of the excavator 3 is operated in response to an operation command from the operating unit inside the cabin 10, and the attachment attaching / detaching device 30 is moved, thereby releasing the engagement of the first hook 33 with the rear support pin 35. This allows the bucket 20 to be detached from the attachment attaching / detaching device 30.

[0137] FIG. 14 shows a state in which an attachment having rear support pins 35a and front support pins 36a with a pin-to-pin distance longer than the distance between the rear support pins 35 and front support pins 36 of the bucket 20 is mounted.

[0138] The attachment attaching / detaching device 30 can change the distance between the first hook 33 and the second hook 34 between a state in which the piston rod 62 of the first hydraulic cylinder 55 is minimally retracted and a state in which it is maximally extended. When the first hydraulic cylinder 55 is maximally extended, the tip E of the second hook 34 is forward of the position (axial center position) of the front support shaft 92 in the extension / retraction direction of the first hydraulic cylinder 55. The third hydraulic cylinder 57 provided on the movable frame 32 is connected to a branch block 61c on the cylinder tube 61 of the first hydraulic cylinder 55 by flexible piping. This piping flexibly deforms when the movable frame 32 rotates in conjunction with the extension of the first hydraulic cylinder 55, and therefore does not restrict the extension of the first hydraulic cylinder 55. Therefore, the movable frame 32 can be rotated relative to the fixed frame 31 to a position in which the tip E of the second hook 34 is forward of the front support shaft 92 in the extension / retraction direction of the first hydraulic cylinder 55. In this way, the rotation angle of the movable frame 32 relative to the fixed frame 31 can be made larger than before, and the distance between the first hook 33 and the second hook 34 can also be made longer than before. With this attachment attaching / detaching device 30, multiple attachments can be connected by using different distances between the support pins.

[0139] With the attachment attaching / detaching device 30 according to this embodiment and the excavator 1 equipped with it as described above, even if the supply of hydraulic pressure to the first hydraulic cylinder 55 is cut off while the bucket 20 is connected to the attachment attaching / detaching device 30, the rear locking member 48 and the front locking member 58, which do not require hydraulic pressure to maintain the locked state of the support pins, can prevent the support pins from falling off the first hook 33 and the second hook 34. Therefore, the connected state of the bucket 20 can be maintained, ensuring a high level of safety.

[0140] The attachment attaching / detaching device 30 of this embodiment supports the support pins (35, 36) of the attachment by extending the first hydraulic cylinder 55, and holds the rear locking member 48 and the front locking member 58 in the locked position by the biasing force of lock springs 83 provided on the rear locking member 48 side and the front locking member 58 side, respectively. The rear locking member 48 is moved from the locked position to the unlocked position by operation of the second hydraulic cylinder 56, and the front locking member 58 is moved from the locked position to the unlocked position by operation of the third hydraulic cylinder 57. The operations of the second hydraulic cylinder 56 and the third hydraulic cylinder 57 at this time are linked to the operation of the first hydraulic cylinder 55.

[0141] With this configuration, good workability is achieved when attaching or detaching the bucket 20 to or from the attachment attaching / detaching device 30, and even if the power supply to the second hydraulic cylinder 56 is cut off due to, for example, damage to the hydraulic equipment, the biasing force of the lock spring 83 ensures that the rear locking member 48 locks the first hook 33 to the rear support pin 35, and that the front locking member 58 locks the second hook 34 to the front support pin 36. This ensures safety.

[0142] Furthermore, in the attachment attaching / detaching device 30, the structure for holding the rear locking member 48 in the locked position and the structure for holding the front locking member 58 in the locked position are formed from members with the same function and shape, and are arranged so as to be mirror images in the front-to-rear direction when viewed from the left side of the attachment attaching / detaching device 30. With this configuration, the first hook 33 and the second hook 34 can share the same retaining member for the support pins (35, 36) of the bucket 20, thereby improving the assembly efficiency of the attachment attaching / detaching device 30. Furthermore, a double lock structure can be easily realized, which can effectively prevent the bucket 20 from detaching from the attachment attaching / detaching device 30, thereby improving safety.

[0143] In addition, in the attachment attaching / detaching device 30, the second hydraulic cylinder 56 is arranged between the first hydraulic cylinder 55 and the right side wall frame portion 41 between the left and right side wall frame portions 41 of the fixed frame 31, and the third hydraulic cylinder 57 is arranged between the first hydraulic cylinder 55 and the right mounting frame portion 45 between the left and right mounting frame portions 45 of the movable frame 32.

[0144] With this configuration, the space between the first hydraulic cylinder 55 and the side wall frame portion 41 can be used as the operating space for the second hydraulic cylinder 56, and the space between the first hydraulic cylinder 55 and the movable frame 32 can be used as the operating space for the third hydraulic cylinder 57, so the attachment attaching / detaching device 30 can be designed compactly.

[0145] The above-described embodiment is merely an example of the present invention, and the attachment attaching / detaching device and construction machine according to the present invention are not limited to the above-described embodiment. Therefore, even if the embodiment is different from the above-described embodiment, various modifications can be made depending on the design, etc., as long as they do not deviate from the technical concept of the present invention.

[0146] For example, in the above-described embodiment, the second hydraulic cylinder 56 is arranged on the right side wall frame portion 41 of the left and right side wall frame portions 41 via the second hydraulic cylinder support shaft 98, and the third hydraulic cylinder is arranged on the right mounting frame portion 45 of the left and right mounting frame portions 45 via the third hydraulic cylinder support shaft 99, but they may also be arranged on the left side wall frame portion 41 and the left mounting frame portion 45, respectively.

[0147] Furthermore, in the above-described embodiment, the hydraulic circuit configuration (see FIG. 11) for operating the first hydraulic cylinder 55 and the second hydraulic cylinder 56 is merely an example. In other words, the hydraulic circuit configuration for operating these hydraulic cylinders is not particularly limited as long as it can obtain the operation of each of the first hydraulic cylinder 55, the second hydraulic cylinder 56, and the third hydraulic cylinder 57 when attaching and removing the bucket as described above.

[0148] The present invention can take the following forms. (1) An attachment attachment / detachment device for a construction machine that attaches and detaches a work attachment to and from an arm of a work device, a first member having a first hook and connected to the arm; a second member having a second hook and pivotally supported by the first member; a first hydraulic cylinder having one end connected to a first support shaft provided on the first member and the other end connected to a second support shaft provided on the second member, for rotating the second member relative to the first member; a first retaining member that is rotatably supported by a third support shaft that is provided on the first member and positioned above the first hook, and that is biased by a first biasing member so as to protrude into an opening of the first hook; a second hydraulic cylinder that, in conjunction with the operation of the first hydraulic cylinder, moves the first retaining member against the biasing force of the first biasing member so as to retreat from the opening of the first hook; a second retaining member that is rotatably supported by a fourth support shaft that is provided on the second member and disposed above the second hook, and that is biased by a second biasing member so as to protrude into an opening of the second hook; a third hydraulic cylinder that, in conjunction with the operation of the first hydraulic cylinder, moves the second retaining member against the second biasing member so as to retract from the opening of the second hook; An attachment attaching / detaching device for a construction machine, comprising: (2) the second hydraulic cylinder is disposed between the first support shaft and the third support shaft, The third hydraulic cylinder is disposed between the second support shaft and the fourth support shaft. An attachment attaching / detaching device for a construction machine as described in (1). (3) The distance between the axis centers of the first support shaft and the second support shaft is shorter than the distance between the axis centers of the third support shaft and the fourth support shaft. An attachment attaching / detaching device for a construction machine as described in (1) or (2). (4) a distance between the axis centers of a fifth support shaft supporting the second hydraulic cylinder and a sixth support shaft supporting the third hydraulic cylinder is shorter than a distance between the axis centers of the third support shaft and the fourth support shaft; (2) An attachment attaching / detaching device for a construction machine. (5) When the rod of the first hydraulic cylinder is fully extended, the tip of the second hook is located forward of the fourth support shaft. An attachment attaching / detaching device for a construction machine according to any one of (1) to (4). (6) the first hydraulic cylinder is a double-acting hydraulic cylinder, the second hydraulic cylinder and the third hydraulic cylinder are single-acting hydraulic cylinders, A branch block is provided inside the first member, which branches into a path that supplies pressure oil to one cylinder chamber of a cylinder tube to contract the rod of the first hydraulic cylinder and simultaneously supplies pressure oil to the second hydraulic cylinder and the third hydraulic cylinder to extend their respective rods, and a path that supplies pressure oil to the other cylinder chamber of the cylinder tube to extend the rod of the first hydraulic cylinder. An attachment attaching / detaching device for a construction machine according to any one of (1) to (5). (7) The branch block is disposed above the cylinder tube of the first hydraulic cylinder. (6) An attachment attaching / detaching device for a construction machine. (8) The end of each rod of the second hydraulic cylinder and the third hydraulic cylinder has a hemispherical shape, and when the second hydraulic cylinder and the third hydraulic cylinder are contracted, the end of the rod protrudes beyond the end of the cylinder tube. (6) An attachment attaching / detaching device for a construction machine. (9) An attachment attaching / detaching device for a construction machine according to any one of (1) to (8), Running gear and a front working device provided on the front side of the traveling device and including the arm that detachably supports the attachment by the attachment attaching / detaching device, Construction machinery. [Explanation of symbols]

[0149] 1 Excavation machine (construction machinery) 2 Running gear 3 Excavation equipment (front work equipment) 18 Arm 20 Bucket (attachment) 30 Attachment detachment device 31 Fixed frame (first member) 32 Movable frame (second member) 33 First Hook 34 Second Hook 35 Front support pin 36 Rear support pin 41 Side wall frame part (wall part) 44 Rear wall 45 Mounting frame (wall) 47 Front wall 48 Rear locking member (first retaining member) 55 First hydraulic cylinder 56 Second hydraulic cylinder 57 Third hydraulic cylinder 58 Front locking member (second retaining member) 81 Bottom side support shaft (first support shaft) 82 Rod side support shaft (second support shaft) 86 Lock spring (first biasing member, second biasing member) 87 Contact part 77a Contact end (end of piston rod) 91 Rear support shaft (3rd support shaft) 93 Front support shaft (4th support shaft) 98 Second hydraulic cylinder support shaft (fifth support shaft) 99 Third hydraulic cylinder support shaft (sixth support shaft)

Claims

1. An attachment attachment / detachment device for a construction machine that attaches and detaches a work attachment to and from an arm of a work device, a first member having a first hook and connected to the arm; a second member having a second hook and pivotally supported by the first member; a first hydraulic cylinder having one end connected to a first support shaft provided on the first member and the other end connected to a second support shaft provided on the second member, for rotating the second member relative to the first member; a first retaining member that is rotatably supported by a third support shaft that is provided on the first member and disposed above the first hook, and that is biased by a first biasing member so as to protrude into an opening of the first hook; a second hydraulic cylinder that, in conjunction with the operation of the first hydraulic cylinder, moves the first retaining member against the biasing force of the first biasing member so as to retreat from the opening of the first hook; a second retaining member that is rotatably supported by a fourth support shaft that is provided on the second member and disposed above the second hook, and that is biased by a second biasing member so as to protrude into an opening of the second hook; a third hydraulic cylinder that moves the second retaining member against the second biasing member so as to retract from the opening of the second hook in conjunction with the operation of the first hydraulic cylinder; An attachment attaching / detaching device for a construction machine, comprising:

2. the second hydraulic cylinder is disposed between the first support shaft and the third support shaft, The third hydraulic cylinder is disposed between the second support shaft and the fourth support shaft.

2. The attachment attaching / detaching device for a construction machine according to claim 1.

3. a distance between the axial centers of the first support shaft and the second support shaft is shorter than a distance between the axial centers of the third support shaft and the fourth support shaft; 2. The attachment attaching / detaching device for a construction machine according to claim 1.

4. a distance between the axis centers of a fifth support shaft supporting the second hydraulic cylinder and a sixth support shaft supporting the third hydraulic cylinder is shorter than a distance between the axis centers of the third support shaft and the fourth support shaft; 3. The attachment attaching / detaching device for a construction machine according to claim 2.

5. When the rod of the first hydraulic cylinder is fully extended, the tip of the second hook is located forward of the fourth support shaft.

2. The attachment attaching / detaching device for a construction machine according to claim 1.

6. the first hydraulic cylinder is a double-acting hydraulic cylinder, the second hydraulic cylinder and the third hydraulic cylinder are single-acting hydraulic cylinders, A branch block is provided inside the first member, which branches into a path that supplies pressure oil to one cylinder chamber of a cylinder tube to contract the rod of the first hydraulic cylinder and simultaneously supplies pressure oil to the second hydraulic cylinder and the third hydraulic cylinder to extend their respective rods, and a path that supplies pressure oil to the other cylinder chamber of the cylinder tube to extend the rod of the first hydraulic cylinder. The attachment attaching / detaching device for a construction machine according to any one of claims 1 to 5.

7. the branch block is disposed above the cylinder tube of the first hydraulic cylinder.

7. The attachment attaching / detaching device for a construction machine according to claim 6.

8. an end of each rod of the second hydraulic cylinder and the third hydraulic cylinder has a hemispherical shape, and when the second hydraulic cylinder and the third hydraulic cylinder are contracted, the end of the rod protrudes beyond the end of the cylinder tube; 7. The attachment attaching / detaching device for a construction machine according to claim 6.

9. The attachment attaching / detaching device for a construction machine according to claim 1; Running gear and a front working device provided on the front side of the traveling device and including the arm that detachably supports the attachment by the attachment attaching / detaching device, Construction machinery.

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