Crushed stone pile forming attachment and crushed stone pile forming device equipped with the same

Abstract

To prevent the normal operation of a clutch mechanism from being impaired.SOLUTION: A crushed stone pile forming attachment includes a cylindrical portion in which a crushed stone input hole is formed, a shaft rotatably disposed within the cylindrical portion, and a clutch mechanism that transmits driving force from the shaft to the cylindrical portion. The clutch mechanism includes a first engagement member 52 fixed to one of the cylindrical portion and the shaft, and a second engagement member 54 rotatably supported to the other of the cylindrical portion and the shaft. When the shaft rotates in the normal rotation direction, the first engagement member and the second engagement member abut and engage, and transmit the rotation of the shaft to the cylindrical portion. When the shaft rotates in the reverse direction, the second engagement member rides over the first engagement member, and the rotation of the shaft is not transmitted to the cylindrical portion.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an attachment for forming a crushed stone pile and a crushed stone pile forming device equipped with the attachment. [Background technology]

[0002] A method for forming crushed stone piles in the ground for ground improvement purposes, such as countermeasures against liquefaction, is known. One method for forming crushed stone piles in the ground involves using an attachment that is inserted into the ground to form a space and then deposits crushed stone into the space. This type of attachment includes a cylindrical portion with a crushed stone inlet and a shaft rotatably disposed within the cylindrical portion. The shaft is connected to a drive unit that generates a rotational driving force. The cylindrical portion is connected to the shaft via a clutch mechanism. When the drive unit generates a rotational driving force in the forward direction, the shaft and the cylindrical portion rotate due to the rotational driving force, and the attachment excavates the ground while being inserted into the ground. Crushed stone is deposited into the space formed by the excavation through a crushed stone inlet provided on the side of the cylindrical portion. When the drive unit generates a rotational driving force in the reverse direction, the shaft rotates in the reverse direction, pressing and discharging the crushed stone deposited in the cylindrical portion into the ground. During this process, the rotation of the shaft is not transmitted to the cylindrical portion, and the cylindrical portion is withdrawn from the ground without rotating. For example, Patent Document 1 discloses an example of an attachment for forming crushed stone piles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-248885 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, this type of attachment uses a clutch mechanism to transmit the rotation of the shaft to the cylindrical portion when excavating underground and to prevent the rotation of the shaft from being transmitted to the cylindrical portion when discharging crushed stone into the ground. Therefore, if the clutch mechanism does not operate properly, the rotation of the shaft in the forward direction will not be transmitted to the cylindrical portion, making it impossible to excavate the ground, or the rotation of the shaft in the reverse direction will be transmitted to the cylindrical portion, making it impossible to discharge crushed stone into the ground. Conventional clutch mechanisms have a risk of being impeded by pebbles or gravel that have entered the mechanism. This specification discloses a technology that prevents the normal operation of the clutch mechanism from being impaired even if pebbles or gravel have entered the clutch mechanism. [Means for solving the problem]

[0005] The attachment disclosed herein is an attachment for forming a crushed stone pile. The attachment is inserted into the ground to form a space, and then crushed stone is poured into the space to form a crushed stone pile. The attachment includes a cylindrical portion having a crushed stone inlet formed in its side, a shaft rotatably disposed within the cylindrical portion and rotated by a driving force transmitted from a drive unit, and a clutch mechanism that transmits the rotation of the shaft to the cylindrical portion so that when a driving force in a forward direction is transmitted from the drive unit to the shaft, the shaft and the cylindrical portion rotate together in the forward direction, and when a driving force in a reverse direction is transmitted from the drive unit to the shaft, the shaft rotates in the reverse direction but the cylindrical portion does not rotate in the reverse direction. The clutch mechanism includes a first engagement member provided on an upper portion of the cylindrical portion and one of the shaft, and a second engagement member provided on the upper portion of the cylindrical portion and the other of the shaft and rotatably supported around a pivot shaft. The second engagement member is rotatable between a first state in which the second engagement member is positioned at a first angle around the pivot shaft and a second state in which the second engagement member is positioned at a second angle around the pivot shaft. When no external force is acting on the second engagement member, the second engagement member is biased by its own weight to change from the second state to the first state. The clutch mechanism is configured so that when the shaft rotates in the forward direction, the second engagement member in the first state engages with the first engagement member to transmit the rotation of the shaft to the cylindrical portion, and when the shaft rotates in the reverse direction, the second engagement member in the first state changes from the first state to the second state and overcomes the first engagement member, thereby not transmitting the rotation of the shaft in the reverse direction to the cylindrical portion.

[0006] In the above-described attachment, when the cylindrical portion and the shaft rotate relative to one another, the first engagement member also rotates integrally with one of the cylindrical portion and the shaft relative to the other. Therefore, a space is formed in the clutch mechanism for the first engagement member to rotate relative to the other of the cylindrical portion and the shaft. Furthermore, because the second engagement member is rotatably supported on the other of the cylindrical portion and the shaft, a space is formed in the clutch mechanism for the second engagement member to rotate. That is, a larger space is formed in the clutch mechanism compared to when the second engagement member is moved linearly. For these reasons, a relatively large space is formed around the first and second engagement members within the clutch mechanism. Therefore, even if pebbles, gravel, or the like get into the clutch mechanism, it is possible to prevent the clutch mechanism from being unable to operate normally. Furthermore, the second engagement member is biased by its own weight to move from the second state to the first state, eliminating the need for a biasing means (such as a spring) to return the second engagement member from the second state to the first state. This simplifies the configuration of the clutch mechanism and prevents the normal operation of the clutch mechanism from being impaired.

[0007] This specification also discloses a crushed stone pile forming device equipped with the above-described attachment. That is, the crushed stone pile forming device disclosed in this specification includes the above-described attachment and a drive device that generates a rotational drive force to drive the attachment. With this crushed stone pile forming device, normal operation of the clutch mechanism is maintained, allowing the crushed stone pile to be formed effectively. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a crushed stone pile forming device according to an embodiment. [Figure 2] A view of the attachment only from a different angle. [Figure 3] FIG. 2 is a partial longitudinal cross-sectional view showing a tip portion of the attachment shown in FIG. 1 . [Figure 4] FIG. 2 is a perspective view showing a schematic configuration of a clutch mechanism. [Figure 5]4 is a diagram illustrating the positional relationship of a knock and a knock pawl that constitute the clutch mechanism when viewed from above. FIG. [Figure 6] FIG. 4 is a diagram for explaining the operation of the clutch mechanism (in a state where the rotational driving force is not transmitted). [Figure 7] FIG. 4 is a diagram for explaining the operation of the clutch mechanism (in a state where a rotational driving force is transmitted). [Figure 8] 10A and 10B are diagrams for explaining the operation of the clutch mechanism of the modified example (in a state where the rotational driving force is not transmitted). [Figure 9] 10A and 10B are diagrams for explaining the operation of the clutch mechanism of the modified example (in a state where a rotational driving force is transmitted). [Figure 10] FIG. 10 is a schematic diagram showing a schematic configuration of a clutch mechanism according to another modified example. [Figure 11] 11 is a diagram for explaining the operation of the clutch mechanism shown in FIG. 10 (in a state in which a rotational driving force is transmitted). FIG. [Figure 12] 11 is a diagram for explaining the operation of the clutch mechanism shown in FIG. 10 (in a state where no rotational driving force is transmitted). FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Feature 1) In the attachment disclosed in this specification, the clutch mechanism may further include a first ring plate fixed to one of the upper part of the cylindrical portion and the shaft, and a second ring plate fixed to the other of the upper part of the cylindrical portion and the shaft. The upper surface of the first ring plate may face the lower surface of the second ring plate. The first engagement member may be a knock provided on the upper surface of the first ring plate. The second engagement member may be a knock pawl rotatably supported on a rotary shaft provided on the lower surface of the second ring plate. With this configuration, a space is formed between the first ring plate and the second ring plate, and the knock and knock pawl are disposed within the space. This allows the knock and knock pawl to be disposed in a relatively large space, making it possible to favorably maintain normal operation of the clutch mechanism.

[0010] (Feature 2) In the attachment disclosed in this specification, the first ring plate may be fixed to the shaft, and the second ring plate may be fixed to an upper portion of the cylindrical portion. [Example]

[0011] Hereinafter, a crushed stone pile forming device 100 according to this embodiment will be described. As shown in Fig. 1, the crushed stone pile forming device 100 includes a soil improvement machine 40 as a construction machine, and an attachment 10 attached to the soil improvement machine 40. As shown in Fig. 1, the soil improvement machine 40 includes a soil improvement machine main body structure 1, a cabin 7 as a driver's seat, crawlers 6 which are endless tracks that can move on uneven ground with low ground pressure, and outriggers 5 that suppress shaking of the soil improvement machine 40 during construction.

[0012] The ground improvement machine 40 further includes, as components for operating the attachment 10, a drive unit 11 that supplies rotational driving force to the attachment 10 via an output shaft 27, a leader 4 having a lifting guide rail 9, a lifting platform 17 that raises and lowers the drive unit 11 and attachment 10 along the lifting guide rail 9, a leader mounting base 2 for supporting the leader 4, a hydraulic cylinder 3 that controls the inclination of the leader 4, and an extension column 8 that is formed integrally with the leader 4 at the lower end of the leader 4.

[0013] As shown in Figures 1 and 2, the attachment 10 comprises a cylindrical portion 12 provided with fins 13, a shaft 22 (shown in Figure 3), a joint rod 26, a spiral portion 14, an enclosing frame 30 for preventing the cylindrical portion 12 from vibrating, a hanger stay 18 attached to the lifting platform 17, a top cover case 16, a crushed stone feeding device 32, a support plate 37 supporting the enclosing frame 30, a support arm 39 supporting the crushed stone feeding device 32, and a construction management device 41 for managing the construction status using the attachment 10.

[0014] The cylindrical portion 12 has a crushed stone injection hole 15 formed in the axial direction on its side surface. The crushed stone injection hole 15 extends in the axial direction of the cylindrical portion 12 and is closed by an opening / closing door 20, which is an elastically deformable door made of rubber or resin.

[0015] The crushed stone feeding device 32 includes a hopper section 33 and a chute section 34 disposed below the hopper section 33. The crushed stone feeding hole 15 is closed by an opening / closing door 20 when the attachment 10 is excavating the ground. This prevents soil and sand from entering the cylindrical section 12 through the crushed stone feeding hole 15. Furthermore, when crushed stone is to be fed into the cylindrical section 12, the opening / closing door 20 is opened. This allows the crushed stone fed into the crushed stone feeding device 32 to be fed into the cylindrical section 12 through the crushed stone feeding hole 15. Furthermore, because the crushed stone feeding hole 15 is provided as an elongated hole along the axial direction, the crushed stone can be fed into the cylindrical section 12 without changing the crushed stone feeding position even when the cylindrical section 12 is raised.

[0016] As shown in Figures 1 and 2, the helical portion 14 is located at the tip of the cylindrical portion 12 and is connected to the tip side of the shaft 22 (shown in Figure 3) so as to be rotatable together. An excavation blade is provided at the tip of the helical portion 14. The excavation blade is formed in a spiral shape with a diameter that increases toward the tip of the helical portion 14. Almost the entire excavation blade is disposed within the cylindrical portion 12, and only a portion of the tip of the excavation blade protrudes from the tip of the cylindrical portion 12. A helical fin 13 is provided on the outer periphery of the cylindrical portion 12. The fin 13 has a helical shape that rotates in the same direction as the helix of the helical portion 14 (i.e., the excavation blade). In other words, during excavation, the cylindrical portion 12 and the helical portion 14 rotate in the same direction. As a result, the excavated soil produced by the excavation of the helical portion 14 is transported to the ground surface by the fin 13.

[0017] As shown in Figure 3, shaft 22 is a member rotatably arranged along its central axis within cylindrical portion 12, and is made of a steel pipe with a fixed diameter (approximately 8 cm). Radial stays 24 are provided at multiple locations within cylindrical portion 12, and bearing pipes 23 are fixed via these radial stays 24. Shaft 22 is supported by being inserted into these bearing pipes 23.

[0018] The base end side of the shaft 22 is connected to a joint rod 26. The joint rod 26 is disposed at the upper end of the cylindrical portion 12 with a portion of it protruding from the top cover case 16, and is connected to an output shaft 27 of the drive unit 11. The joint rod 26 rotates in response to the rotational driving force of the output shaft 27, and transmits the rotational driving force to the helical portion 14 via the shaft 22, which is integrally connected to the joint rod 26. A ring plate 51 (an example of a "first ring plate") is fixed to the joint rod 26. The ring plate 51 is located at the lower end inside the top cover case 16. A small gap is formed between the outer peripheral surface of the ring plate 51 and the inner peripheral surface of the top cover case 16, allowing the ring plate 51 to rotate with respect to the top cover case 16.

[0019] The top cover case 16 (an example of an "upper part of the cylindrical portion") is cylindrically formed, attached to the rear end (base end) of the cylindrical portion 12, and integrated with the cylindrical portion 12. A ring-shaped ring plate 55 (an example of a "second ring plate") is disposed at the upper end of the top cover case 16. Therefore, the lower surface of the ring plate 55 faces the upper surface of the ring plate 51. The outer periphery of the ring plate 55 is fixed to the top cover case 16 by welding or the like, and the upper end of the top cover case 16 is closed by the ring plate 55. The joint rod 26 passes through a central through-hole of the ring plate 55. A bearing portion 57 is provided in the ring plate 55, and the joint rod 26 is rotatably supported by the bearing portion 57. Therefore, even if the joint rod 26 (shaft 22) is rotationally driven, the cylindrical portion 12 does not rotate together with the joint rod 26 (shaft 22) and remains free. As is clear from the above description, the gap between the ring plate 55 and the joint rod 26 is closed by the bearing portion 57.

[0020] A clutch mechanism C1 is disposed inside the top cover case 16. When the drive device 11 drives the helical portion 14 in the rotation direction during excavation, the clutch mechanism C1 rotates the helical portion 14 (i.e., the joint rod 26 and shaft 22) and the cylindrical portion 12 as a single unit. On the other hand, when the drive device 11 drives the helical portion 14 in the direction opposite to the rotation direction during excavation, the clutch mechanism C1 rotates the helical portion 14 (i.e., the joint rod 26 and shaft 22) in the reverse direction, while interrupting the transmission of power from the helical portion 14 (i.e., the joint rod 26 and shaft 22) to the cylindrical portion 12 to stop the rotation of the cylindrical portion 12. Hereinafter, the direction in which the cylindrical portion 12 and the helical portion 14 rotate in the same direction, i.e., the rotation direction during excavation, will be referred to as the "forward direction," and the direction in which they rotate in the direction opposite to the rotation direction during excavation will be referred to as the "reverse direction." In addition, the rotation in the forward direction will be described as right rotation (clockwise), and the rotation in the reverse direction will be described as left rotation (counterclockwise).

[0021] 4 to 7, the clutch mechanism C1 is made up of a ring plate 51 fixed to the joint rod 26 (shaft 22), a ring plate 55 fixed to the top cover case 16 (cylindrical portion 12), a knock 52 provided on the upper surface of the ring plate 51, and a knock pawl 54 rotatably supported on the lower surface of the ring plate 55. Note that in FIG. 4, the top cover case 16, ring plate 55, etc. are not shown in order to illustrate the knock pawl 54 and knock 52.

[0022] As shown in Fig. 5, two knocks 52 are provided on the upper surface of the ring plate 51. In a plan view, the two knocks 52 are arranged at positions that are point-symmetric with respect to the rotation axis A of the joint rod 26. As shown in Figs. 6 and 7, the knock 52 has a triangular shape in a side view, and has a first inclined surface 52a that forms an acute angle with the upper surface of the ring plate 51 and a second inclined surface 52b that forms an obtuse angle with the upper surface of the ring plate 51.

[0023] As shown in FIGS. 4, 6, and 7, the knock pawl 54 is attached to the underside of the ring plate 55 via a mounting plate 58. Specifically, the knock pawl 54 has a pivot shaft 56, which is pivotally supported by a pair of mounting plates 58, which are fixed to the underside of the ring plate 55. This allows the knock pawl 54 to be pivotally supported relative to the ring plate 55. As is apparent from FIGS. 6 and 7, the distance between the ring plate 51 and the ring plate 55 is shorter than the length from the tip to the base end of the knock pawl 54. Therefore, the knock pawl 54 cannot rotate around the axis of the pivot shaft 56, but can rotate between an angular position where the knock pawl 54 abuts on the top surface of the ring plate 51 (the state shown in FIG. 7 (an example of a "first state")) and an angular position where the knock pawl 54 overcomes the knock 52 (the state shown in FIG. 6 (an example of a "second state")). The knock pawl 54 is not biased by a spring or the like, but is acted upon only by gravity. Therefore, when no external force is acting on the knock pawl 54, the knock pawl 54 is biased by its own weight from the state shown in FIG. 6 to the state shown in FIG.

[0024] As shown in FIG. 5, two knock pawls 54 are attached to the underside of the ring plate 55. In a plan view, the two knock pawls 54 are arranged in positions that are point-symmetric with respect to the rotation axis A of the joint rod 26. The two knock pawls 54 are also arranged relative to the two knocks 52 so that when one knock pawl 54 engages with one knock 52, the other knock pawl 54 engages with the other knock 52. As shown in FIGS. 6 and 7, the knock pawls 54 have a pointed shape that is larger on the rotation axis 56 side and smaller toward the tip. The pointed (wedge-shaped) tip of the knock pawl 54 is configured to engage between the first inclined surface 52a of the knock 52 and the upper surface of the ring plate 51.

[0025] Next, the operation of the crushed stone pile forming device 100 when the crushed stone pile forming device 100 forms a crushed stone pile will be described.

[0026] First, the attachment 10 is aligned. The alignment of the attachment 10 is performed by adjusting the position and direction of the soil improvement machine 40 by driving the crawler 6. After adjusting the position and direction of the soil improvement machine 40, the soil improvement machine 40 may be fixed to the ground by the outriggers 5. This makes it possible to suppress shaking and displacement of the soil improvement machine 40 during construction.

[0027] Next, the attachment 10 is inserted into the ground to excavate the ground. Specifically, after the soil improvement machine 40 is fixed to the ground, the attachment 10 is lowered while the drive unit 11 is driven. At this time, the drive unit 11 is driven to generate a rotational drive force in the forward direction. When the drive unit 11 generates a rotational drive force in the forward direction, the clutch mechanism C1 causes the spiral portion 14 and the cylindrical portion 12 to rotate in the forward direction. In other words, when the drive unit 11 generates a rotational drive force in the forward direction, the joint rod 26 and the shaft 22 rotate in the forward direction, which causes the ring plate 51 fixed to the joint rod 26 to also rotate in the forward direction. Here, the angular position of the knock pawl 54 around the rotation axis 56 is such that its tip abuts against the upper surface of the ring plate 51 due to its own weight (the state shown in FIG. 7). 7, when the ring plate 51 rotates in the forward direction, the knock pawl 54 comes into contact with the first inclined surface 52a of the knock 52 fixed to the upper surface of the ring plate 51. At this time, the tip of the knock pawl 54 engages in the gap between the first inclined surface 52a of the knock 52 and the upper surface of the ring plate 51, and the knock pawl 54 becomes unable to rotate. Therefore, when the ring plate 51 (i.e., the joint rod 26) rotates in the forward direction, the ring plate 55 also rotates in the forward direction accordingly. Because the ring plate 55 rotates in the forward direction, the top cover case 16 and the cylindrical portion 12 fixed to the ring plate 55 also rotate in the forward direction.

[0028] As described above, the helical portion 14 and the cylindrical portion 12 rotate in the forward direction, causing the attachment 10 to be inserted into the ground and excavate. The soil and sand excavated from the ground is carried to the outer periphery of the cylindrical portion 12 and discharged to the ground surface by the fins 13. When the attachment 10 reaches a predetermined depth, the forward rotation of the drive unit 11 is stopped, and excavation ends.

[0029] Next, the attachment 10 is raised, and a crushed stone pile is formed in the ground. The formation of a crushed stone pile is performed in the following procedure. First, with the opening and closing door 20 open, crushed stone is fed into the crushed stone feeding device 32. The crushed stone fed into the crushed stone feeding device 32 is fed into the cylindrical portion 12 through the crushed stone feeding hole 15. Next, the drive device 11 is driven so as to generate a rotational driving force in the reverse direction. This causes the spiral portion 14 to rotate in the reverse direction, and the crushed stone fed into the cylindrical portion 12 is discharged out of the cylindrical portion 12 while being pressed by the spiral portion 14. As a result, the attachment 10 is pushed out of the ground, and a crushed stone pile is formed in the space formed by the cylindrical portion 12.

[0030] When the drive unit 11 generates a rotational driving force in the reverse direction, the clutch mechanism C1 causes only the spiral portion 14 to rotate in the reverse direction, and the cylindrical portion 12 does not rotate in either the forward or reverse direction. That is, when the drive unit 11 generates a rotational driving force in the reverse direction, the joint rod 26 and the shaft 22 rotate in the reverse direction, causing the ring plate 51 fixed to the joint rod 26 to also rotate in the reverse direction. Here, the tip of the knock pawl 54 abuts against the upper surface of the ring plate 51 due to its own weight. Therefore, when the ring plate 51 rotates in the reverse direction, the knock pawl 54 abuts against the second inclined surface 52b of the knock 52, as shown in FIG. 6. When the joint rod 26 and the ring plate 51 further rotate in the reverse direction after abutting against the second inclined surface 52b of the knock pawl 54, the knock pawl 54 is guided by the second inclined surface 52b and rotates around the pivot shaft 56, moving to a position where it clears the knock 52 (the state shown in FIG. 6). As the ring plate 51 continues to rotate in the reverse direction, the knocking claw 54 rotates around the pivot 56 due to its own weight, returning to a position where its tip abuts the top surface of the ring plate 51. Thereafter, while the ring plate 51 continues to rotate in the reverse direction, the knocking claw 54 repeatedly climbs over the knock 52. As a result, the rotation of the joint rod 26 in the reverse direction is not transmitted to the cylindrical portion 12, and the cylindrical portion 12 maintains its stopped rotation. This prevents the position of the crushed stone injection hole 15 provided in the cylindrical portion 12 from changing circumferentially, allowing crushed stone to be injected into the cylindrical portion 12 without adjusting the position of the crushed stone injection device 32. When the attachment 10 is pushed to the ground surface, the drive unit 11 stops driving in the reverse direction, and the formation of the crushed stone pile is completed.

[0031] In the attachment 10 of this embodiment, a relatively large space is formed between the ring plates 51 and 55, and the knock 52 and knock pawl 54 are disposed within this space. Therefore, even if soil or pebbles enter the space between the ring plates 51 and 55, this prevents the knock pawl 54 from interfering with its normal operation. Furthermore, the knock pawl 54 is rotatably supported on the underside of the ring plate 55, and no mechanical element such as a spring is provided to bias the knock pawl 54. Therefore, the knock pawl 54 can freely rotate in the space below the ring plate 55, preventing soil or pebbles from becoming caught between the knock pawl 54 and the knock 52. As a result, the clutch mechanism C1 operates normally, allowing the crushed stone pile to be formed properly.

[0032] In the above-described embodiment, the clutch mechanism C1 is configured by the knock pawl 54 rotatably supported on the lower surface of the ring plate 55 and the knock 52 provided on the upper surface of the ring plate 51. However, the technology disclosed in this specification is not limited to this example. For example, as shown in FIGS. 8 and 9 , a knock 66 may be provided on the lower surface of the ring plate 55, and the knock pawl 64 may be rotatably supported on the upper surface of the ring plate 51. In this configuration, the knock pawl 64 is attached to the upper surface of the ring plate 51 via an attachment plate 60 and is supported by the attachment plate 60 so as to be rotatable about a rotation shaft 62. The knock pawl 64 rotates about the rotation shaft 62, thereby switching between a state in which the lower end of the knock pawl 64 is separated from the upper surface of the ring plate 51 (the state shown in FIG. 8 ) and a state in which the lower end of the knock pawl 64 abuts against the upper surface of the ring plate 51 (the state shown in FIG. 9 ). Because the center of gravity of the knock pawl 64 is located to the right of the position of the rotation shaft 62, the knock pawl 64 is urged by its own weight from the state shown in Figure 8 to the state shown in Figure 9. Even in this configuration, when the joint rod 26 and the shaft 22 rotate in the forward direction, the knock pawl 64 and the knock 66 engage with each other, and the forward rotation of the joint rod 26 and the shaft 22 can be transmitted to the cylindrical portion 12. Furthermore, when the joint rod 26 and the shaft 22 rotate in the reverse direction, the knock pawl 64 overcomes the knock 66, and therefore, the reverse rotation of the joint rod 26 and the shaft 22 is not transmitted to the cylindrical portion 12.

[0033] 10 to 12, the clutch mechanism may be formed by a first rod-shaped member 72 rotatably supported on the lower surface of a ring plate 70 fixed to the cylindrical portion 12, and a second rod-shaped member 76 fixed to the joint rod 26. In this example, the first rod-shaped member 72 has a rotation shaft 74 at its upper end, and a lower portion thereof is capable of contacting the second rod-shaped member 76. The first rod-shaped member 72 is not provided with a biasing means such as a spring, and is in a hanging state due to its own weight when no external force is applied (the state shown in FIGS. 10 and 11). Furthermore, the first rod-shaped member 72 can rotate in one direction from the hanging state, but its rotation is restricted by a stopper 78 so that it cannot rotate in the other direction. Meanwhile, the second rod-shaped member 76 extends radially from the joint rod 26 and is capable of contacting the first rod-shaped member 72. In this configuration, when the joint rod 26 rotates in the forward direction, the second rod-shaped member 76 abuts against the first rod-shaped member 72. At this time, the rotation of the first rod-shaped member 72 is restricted by the stopper 78, so that the second rod-shaped member 76 and the first rod-shaped member 72 rotate together in the forward direction, causing the cylindrical portion 12 to rotate in the forward direction (the state shown in FIG. 11 ). On the other hand, when the joint rod 26 rotates in the reverse direction, the second rod-shaped member 76 abuts against the first rod-shaped member 72, causing the first rod-shaped member 72 to rotate about the rotation axis, causing the first rod-shaped member 72 to climb over the second rod-shaped member 76, and only the second rod-shaped member 76 rotates in the reverse direction together with the joint rod 26. This prevents the rotation of the joint rod 26 in the reverse direction from being transmitted to the cylindrical portion 12.

[0034] Furthermore, although the present embodiment has been described as an attachment 10 of a type that discharges excavated earth and sand to the ground surface (a so-called earth discharge type), the present invention is not limited to such an example. The technology disclosed in this specification can also be employed, for example, in a non-earth discharge type attachment that does not discharge excavated earth and sand to the ground surface.

[0035] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. [Explanation of symbols]

[0036] 10 Attachments 11 Drive unit 12 Cylindrical part 15 Crushed stone injection hole 51,55 Ring plate 52 Knock 54 Knock Claw 100 Crushed stone pile forming device C1 clutch mechanism

Claims

1. An attachment for forming a crushed stone pile that is inserted into the ground to form a space and then pours crushed stone into the space to form a crushed stone pile, a cylindrical portion having a crushed stone injection hole formed on its side; a shaft rotatably disposed within the cylindrical portion and rotated by a driving force transmitted from a driving device; a clutch mechanism that transmits the rotation of the shaft to the cylindrical portion so that, when a driving force in a forward rotation direction is transmitted from the drive device to the shaft, the shaft and the cylindrical portion rotate integrally in the forward rotation direction, and, when a driving force in a reverse direction is transmitted from the drive device to the shaft, the shaft rotates in the reverse direction while the cylindrical portion does not rotate in the reverse direction; The clutch mechanism includes: a first engagement member provided on one of the upper portion of the cylindrical portion and the shaft; a second engagement member supported rotatably around a rotation axis provided on the other of the upper portion of the cylindrical portion and the shaft, the second engagement member is rotatable between a first state in which the angular position around the rotation axis is a first angle and a second state in which the angular position around the rotation axis is a second angle, the second engaging member is biased by its own weight to move from the second state to the first state when no external force is acting on it, The clutch mechanism includes: When the shaft rotates in the forward direction, the second engaging member in the first state engages with the first engaging member to transmit the rotation of the shaft to the cylindrical portion, An attachment for forming crushed stone piles that is configured such that when the shaft rotates in the reverse direction, the second engaging member in the first state changes from the first state to the second state and overcomes the first engaging member, thereby preventing the rotation of the shaft in the reverse direction from being transmitted to the cylindrical portion.

2. the clutch mechanism further includes a first ring plate fixed to one of an upper portion of the cylindrical portion and the shaft, and a second ring plate fixed to the other upper portion of the cylindrical portion and the shaft, an upper surface of the first ring plate facing a lower surface of the second ring plate; the first engagement member is a knock provided on an upper surface of the first ring plate, 2. The attachment for forming a crushed stone pile according to claim 1, wherein the second engaging member is a knock pawl rotatably supported on the rotating shaft provided on the underside of the second ring plate.

3. the first ring plate is fixed to the shaft, The crushed stone pile forming attachment according to claim 2 , wherein the second ring plate is fixed to an upper portion of the cylindrical portion.

4. An attachment according to any one of claims 1 to 3; A crushed stone pile forming device comprising: a drive device that generates rotational driving forces in a forward rotation direction and a reverse rotation direction to drive the attachment.

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