JP7654989B2 - crane - Google Patents

Description

The present invention relates to a crane.

Conventionally, cranes equipped with a crane body and a boom are known. The boom is supported by the crane body so that it can be raised and lowered around a horizontal rotation axis. In addition, one such crane further equipped with a pair of left and right backstops interposed between the boom and the crane body to prevent the boom from tipping backward is known. Each backstop is extendable and retractable, and its base end is rotatably supported by the boom. When the crane is assembled, each backstop is placed in a support position in which it intersects with the back of the boom and can support the boom. When the boom is raised relative to the crane body with each backstop in the support position, the tip of each backstop eventually abuts against a backstop receiving portion provided on the crane body. As a result, the pair of backstops support the boom and prevent further rotation of the boom, i.e., preventing the boom from tipping backward.

On the other hand, when the crane is being transported or stored, each backstop as described above is rotated around its base end as a fulcrum and placed in a stored position overlapping the back of the boom. As a result, the space required for the boom on the transport vehicle or in the storage area can be reduced.

Patent Document 1 discloses a backstop that can be separated into a base end support shaft that is rotatably supported on the crane body, and a tip end support shaft that is rotatably supported on the boom. The tip end support shaft can be raised and lowered relative to the boom, and when the tip end support shaft stands up relative to the boom, the tip end support shaft and the base end support shaft are connected to each other, and the backstop can support the boom as the boom stands up.

JP 2007-290782 A

In the technology described in Patent Document 1, if the boom is mistakenly raised while the tip support shaft of the backstop is lying down relative to the boom, the tip support shaft will interfere with a part of the crane body other than the base support shaft, causing damage to the backstop or part of the crane body.

The present invention was made in consideration of the above problems, and aims to prevent interference between a backstop supported on a boom of a crane so that it can be raised and lowered, and the crane body when the boom is raised and lowered.

The crane according to one embodiment of the present invention includes a crane body having a backstop receiving portion facing upward, a boom, a boom hoisting drive unit, a backstop, a posture detection unit, and a boom hoisting prevention unit. The boom includes a boom base end supported forward of the backstop receiving portion so as to be rotatable in the hoisting direction around a boom rotation axis horizontal to the crane body, and a boom tip end opposite the boom base end. The boom hoisting drive unit receives a hoisting command signal and is capable of hoisting the boom relative to the crane body in response to the hoisting command signal. The backstop includes a backstop base end supported on a portion of the boom closer to the boom tip than the boom base end so as to be rotatable around a reference rotation axis parallel to the boom rotation axis, and a backstop tip end disposed opposite the backstop base end. The backstop can be changed in posture between a support posture and a storage posture by rotating around the reference rotation axis. The support posture is a posture in which the backstop extends diagonally upward from the boom in the collapsed state so that the backstop can restrict the boom from collapsing backward when the backstop tip abuts on the backstop receiving portion of the crane body as the boom rises from the collapsed state of the boom relative to the crane body. The storage posture is a posture in which the backstop tip of the backstop is positioned closer to the boom than the support posture. The posture detection unit is capable of detecting that the backstop is in at least one of the support posture and the storage posture. The boom hoist prevention unit prevents the boom hoisting operation by the boom hoist drive unit regardless of the input of the hoist command signal when the backstop is in the storage posture and the boom hoist angle, which is the relative angle of the boom to the crane body, is within a preset interference prevention angle range to prevent interference between the backstop tip and a portion of the crane body other than the backstop receiving portion.

With this configuration, even if the boom is raised or lowered while the backstop is in the stored position, if the boom hoisting angle falls within the interference prevention angle range, the boom hoisting prevention section can forcibly prevent the boom from being hoisted, thereby preventing interference between the tip of the backstop and the crane body.

In the above configuration, the boom can be lowered forward relative to the crane body until the boom hoisting angle reaches the maximum hoisting angle, and the maximum hoisting angle is the relative angle of the boom to the crane body when the boom is in the maximum hoisting state so that the center line of the boom extends forward and downward from the boom rotation center axis, and the interference prevention angle range has a lower limit angle greater than the maximum hoisting angle that is set to prevent the tip of the backstop from interfering with the front part of the crane body, and it is preferable that the boom hoisting prevention unit inputs a forced stop signal to the boom hoisting drive unit to forcibly stop the raising operation of the boom when the boom is raised from the maximum hoisting angle by the boom hoisting drive unit with the backstop in the stored position and the boom hoisting angle reaches the lower limit angle.

With this configuration, even if the boom is raised from the maximum hoisting angle with the backstop in the stored position, when the boom hoisting angle reaches the lower limit of the interference prevention angle range, the boom hoisting prevention section forcibly stops the boom hoisting operation, thereby preventing interference between the tip of the backstop and the front part of the crane body. Therefore, even if an operator raises the boom without first changing the position of the backstop to the support position during the crane assembly work, the above-mentioned interference can be reliably prevented.

In the above configuration, the boom is capable of supporting a load connected to the boom tip when the boom is raised relative to the crane body and the boom hoisting angle is within a preset work angle range, the interference prevention angle range has an upper limit angle greater than the lower limit angle, and the upper limit angle is set to an angle smaller than the work angle range, and it is desirable that the boom hoisting prevention unit allows the boom hoisting operation by the boom hoisting drive unit regardless of the magnitude of the boom hoisting angle when the boom hoisting angle is within the work angle range.

With this configuration, when the boom hoisting angle is within the working angle range, the boom hoisting prevention unit does not prevent the boom from being hoisted, so even if the posture detection unit erroneously detects the posture of the backstop, it is possible to prevent the boom from stopping against the operator's intention.

In the above configuration, it is preferable to further include an alarm device that notifies an operator of warning information when the boom hoisting angle falls within the interference prevention angle range with the backstop in the stored position.

This configuration notifies the worker that there is a risk of interference between the tip of the backstop and the crane body, allowing the worker to understand why the boom raising and lowering has stopped and reducing the chance of the worker raising and lowering the boom with the backstop in the stored position during subsequent work.

In the above configuration, it is preferable to further include a backstop position change unit that can change the position of the backstop between the support position and the storage position by rotating the backstop around the reference rotation center axis.

With this configuration, if the boom hoisting prevention unit forcibly stops the boom hoisting operation, the backstop can be changed from the stored position to the support position, allowing the boom hoisting operation to be resumed quickly.

In the above configuration, the crane further includes a gantry having a gantry base end supported by the crane body behind the boom base end and in front of the backstop receiving part, and supporting the boom so that the boom can be raised and lowered, the crane body further includes a gantry support part that is positioned so as to overlap the backstop when viewed from the front-rear direction and supports the gantry base end, and the interference prevention angle range may be set to prevent the backstop tip and the gantry support part from interfering with each other when the boom is raised with the backstop in the stored position.

With this configuration, even if a gantry is placed behind the boom and the gantry support part for supporting the gantry is placed in a position in front of the backstop receiving part that is likely to interfere with the tip of the backstop, interference between the tip of the backstop and the gantry support part can be prevented.

In addition, in the above configuration, it is desirable that the height of the backstop in the supporting position relative to the base end of the boom is set so that when the backstop is in the supporting position and the boom is raised from the collapsed state, the tip of the backstop moves rearward above the portion of the crane body that is forward of the backstop receiving portion and then comes into contact with the backstop receiving portion.

With this configuration, when the backstop is in the supporting position, the tip of the backstop can pass above the front part of the crane body, so interference between the tip of the backstop and the crane body can be reliably prevented.

According to the present invention, it is possible to prevent interference between the backstop, which is supported on the boom of a crane so that it can be raised and lowered, and the crane body when the boom is raised and lowered.

FIG. 1 is a side view of a crane according to an embodiment of the present invention. FIG. 2 is a side view of a lower boom and a backstop when the boom of the crane according to one embodiment of the present invention is in a lowered position. FIG. 2 is a plan view of a lower boom and a backstop when the boom of the crane according to one embodiment of the present invention is in a lowered position. FIG. 2 is a side view of a state in which the backstop is placed in a supporting position by the backstop position changing device in the crane according to one embodiment of the present invention. FIG. 2 is a side view of a crane according to one embodiment of the present invention, in which the backstop is placed in a supporting position by the backstop position changing device and the boom is raised. FIG. 2 is a schematic diagram showing a hydraulic circuit of a backstop attitude changing device in a crane according to one embodiment of the present invention. FIG. 2 is a block diagram of a crane according to an embodiment of the present invention. FIG. 2 is an enlarged side view of the backstop of the crane in a stowed position according to one embodiment of the present invention. FIG. 2 is an enlarged side view of the backstop of the crane in a support position according to one embodiment of the present invention. FIG. 2 is a side view showing a state in which a boom is raised in the crane according to the embodiment of the present invention. FIG. 2 is a plan view showing a state in which a boom is raised in the crane according to one embodiment of the present invention. FIG. 12 is an enlarged side view showing the state in which the tip of the backstop interferes with the crane body, as viewed along the arrows XII-XII in FIG. 11 . 5 is a flowchart of a boom raising operation control in the crane according to the embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a side view of a crane 10 (work machine) according to one embodiment of the present invention. Note that although the directions of "up," "down," "front," and "rear" are shown in each figure hereafter, these directions are shown for the sake of convenience in explaining the structure and assembly method of the crane 10 according to this embodiment, and do not limit the direction of movement or the manner of use of the crane according to the present invention.

The crane 10 includes an upper rotating body 12, a lower running body 14, a boom 16, a lower spreader 18, an upper spreader 19, guy lines 20, a gantry 21, a boom raising and lowering rope 22, a boom raising and lowering winch 30, a main winch 34, an auxiliary winch 35, a counterweight 40, and a backstop 45.

The upper rotating body 12 constitutes the crane body of the crane 10 and is supported by the lower running body 14 so that it can rotate around a central axis of rotation that extends in the vertical direction. The lower running body 14 can run on a running surface such as the ground G.

The boom 16 has a boom base end 16P supported on the upper rotating body 12 so as to be rotatable in the hoisting direction around a horizontal boom rotation center axis, and a boom tip end 16Q arranged on the opposite side of the boom base end 16P in the longitudinal direction. In this embodiment, a boom foot 16S provided on the boom base end 16P is rotatably supported on a shaft support (not shown) of the upper rotating body 12. The boom 16 shown in FIG. 1 is a so-called lattice type, and is composed of a lower boom 16A including a boom foot 16S, one or more (one in the illustrated example) intermediate booms, and an upper boom. A pair of left and right backstops 45 are supported on the lower boom 16A. These backstops 45 each abut against the upper rotating body 12 when the boom 16 is further raised from the state shown in FIG. 1 to an upright position (working position). This abutment prevents the boom 16 from being blown backward by strong winds, etc. The structure of the backstop 45 will be described in detail later.

The lower spreader 18 is connected to the tip of the gantry 21 and has a lower sheave block (not shown). The lower sheave block has multiple sheaves arranged in the width direction (left-right direction).

The upper spreader 19 is disposed at a predetermined distance in front of the lower spreader 18. The upper spreader 19 is connected to the boom tip 16Q via the guy lines 20. The upper spreader 19 has an upper sheave block (not shown). The upper sheave block has multiple sheaves arranged in the width direction (left-right direction). A pair of guy lines 20 are disposed in the left-right direction perpendicular to the plane of the paper in FIG. 1. The rear end of the guy line 20 is connected to the upper spreader 19, and the front end of the guy line 20 is detachably connected to the boom tip 16Q. The guy lines 20 include guy links (metal plate material), guy ropes, guy wires (metal wire material), etc.

The gantry 21 is supported by the upper rotating body 12 behind the boom 16. As shown in FIG. 1, the gantry 21 is composed of two structures that form a roughly triangle with the upper rotating body 12. The rear part of the gantry 21 is also called a tension member, and extends roughly vertically upward from the rear end of the upper rotating body 12. The front part of the gantry 21 is also called a compression member, and connects the upper end of the tension member to the front part of the upper rotating body 12 along a diagonal direction. The tension member and compression member of the gantry 21 are foldable, and can be stored on the upper rotating body 12. The gantry 21 supports the boom 16 from the rear so that the boom 16 can be raised and lowered.

The boom hoisting rope 22 is pulled out from the boom hoisting winch 30 and hung around a sheave (not shown) located at the tip of the tension member, and then wound around the lower sheave block of the lower spreader 18 and the upper sheave block of the upper spreader 19 multiple times. After being wound around the lower sheave block and the upper sheave block, the tip of the boom hoisting rope 22 is fixed to the tip (upper end) of the gantry 21.

The boom hoist winch 30 is disposed on the upper rotating body 12. The boom hoist winch 30 changes the distance between the lower sheave block of the lower spreader 18 and the upper sheave block of the upper spreader 19 by winding and unwinding the boom hoist rope 22, thereby raising and lowering the boom 16 while rotating the boom 16 relative to the gantry 21.

The main winch 34 hoists and lowers the load using the main hoist rope 51 (Fig. 1). For this main hoist, a main hoist guide sheave (not shown) is rotatably provided at the boom tip 16Q of the boom 16, and a main hoist sheave block is provided adjacent to the main hoist guide sheave, with multiple main hoist point sheaves arranged in the width direction. A main hook 53 for the load is connected to the main hoist rope 51 suspended from the main hoist sheave block. The main hoist rope 51 drawn out from the main hoist winch 34 is hung in order on the main hoist guide sheaves, and is hung between the sheave of the main hoist sheave block and the sheave of the sheave block provided on the main hook 53. Therefore, when the main hoist winch 34 winds and unwinds the main hoist rope 51, the main hook 53 is hoisted and lowered.

Similarly, the auxiliary winch 35 hoists and lowers the load using the auxiliary hoist rope 52. This auxiliary hoisting has a structure (not shown) similar to that of the main hoist described above. When the auxiliary hoist winch 35 winds or unwinds the auxiliary hoist rope 52, the auxiliary hook 54 for the load connected to the end of the auxiliary hoist rope 52 is hoisted or lowered.

In addition, a counterweight 40 is mounted on the rear of the upper rotating body 12 to adjust the balance of the crane 10.

Figures 2 and 3 are a side view and a plan view of the lower boom 16A and the backstop 45 when the boom 16 of the crane 10 according to this embodiment is in a lowered position. Figure 4 is a side view of the crane 10 according to this embodiment with the backstop 45 in a supporting position by the backstop lifting device 60 (backstop position changing device). Figure 5 is a side view of the crane 10 according to this embodiment with the backstop 45 in a supporting position by the backstop lifting device 60 and the boom 16 in an upright position.

Referring to Figures 2 to 5, when the boom 16 (lower boom 16A) is viewed in a state in which it is lowered relative to the upper rotating body 12, the lower boom 16A has a pair of left and right lower frames 160, a pair of left and right first main pipes 161, a pair of left and right second main pipes 162, a pair of left and right first connecting pipes 163, a pair of upper and lower second connecting pipes 164 (Figure 3), and a plurality of lattice pipes 165.

The pair of left and right first main pipes 161 and the pair of left and right second main pipes 162 are pipes that define the outer shape of the lower boom 16A, and extend from the vicinity of the boom foot 16S toward the tip side of the lower boom 16A so that the distance between them increases, as shown in FIG. 2 and other figures. The lower frame 160 is a plate-like member that connects the base ends of the first main pipes 161 and the second main pipes 162 to each other on both the left and right sides of the lower boom 16A. The pair of left and right first connecting pipes 163 connect the tips of the first main pipes 161 and the second main pipes 162 to each other. In addition, the pair of upper and lower second connecting pipes 164 connect the tips of the pair of left and right first main pipes 161 to each other and the tips of the pair of left and right second main pipes 162 to each other. The multiple lattice pipes 165 connect the first main pipe 161 and the second main pipe 162, the left and right pair of first main pipes 161, and the left and right pair of second main pipes 162 to each other at multiple locations.

The lower boom 16A further has a pair of left and right brackets 161S. The pair of left and right brackets 161S are disposed on the first main pipe 161 between the boom foot 16S and the tip of the first main pipe 161, more specifically, at a position close to the tip of the first main pipe 161. The brackets 161S rotatably support the backstop fulcrum portion 452S of the backstop 45 described below.

As mentioned above, the crane 10 is equipped with a pair of left and right backstops 45. The crane 10 further includes a pair of left and right backstop lifting devices 60 (backstop position changing devices) that can be mounted between the backstops 45 and the boom 16. Each backstop 45 is disposed on a pair of left and right first main pipes 161. The pair of left and right backstops 45 and the pair of left and right backstop lifting devices 60 have the same structure and function, so hereafter, only the backstop 45 and backstop lifting device 60 on the right side (the front side of the paper in FIG. 2) will be described.

The backstop 45 has a lower backstop part 451, an upper backstop part 452, and a backstop spring 453. The lower backstop part 451 and the upper backstop part 452 have a cylindrical structure, and the lower backstop part 451 is inserted into the cylindrical interior of the upper backstop part 452 so that it can expand and contract. The backstop spring 453 is mounted in a compressible manner between the flanges F (Figure 2) provided on the lower backstop part 451 and the upper backstop part 452, respectively.

The backstop lower part 451 has a backstop abutment part 451S, and the backstop upper part 452 has a backstop fulcrum part 452S. The backstop fulcrum part 452S corresponds to the base end part (backstop base end) of the backstop 45, and the backstop abutment part 451S corresponds to the tip part (backstop tip part) of the backstop 45 on the opposite side to the backstop fulcrum part 452S. As described above, the backstop fulcrum part 452S is supported rotatably around a horizontal rotation center axis (a rotation center axis extending in the left-right direction of the upper rotating body 12, a reference rotation center axis) on the bracket 161S arranged on the tip side of the lower boom 16A (a part closer to the boom tip part 16Q) than the boom foot 16S.

Referring to FIG. 5, the upper rotating body 12 includes a rotating frame 120, which has a pair of left and right boom mounting parts 12S that rotatably support the boom foot 16S, and a pair of left and right backstop receiving parts 121 that are arranged to face upward. Note that in FIG. 5, only the backstop receiving part 121 on the right side (the front side of the page) is visible. The boom base end part 16P that is supported by the boom mounting part 12S is disposed in front of the backstop receiving part 121.

The backstop lifting device 60 (FIGS. 2 and 4) can change the position of the backstop 45 between a support position (FIG. 4) and a storage position (FIG. 2) by rotating the backstop 45 about the backstop fulcrum 452S (reference rotation center axis) as a fulcrum when the boom 16 is in a collapsed state relative to the upper rotating body 12. The support position is a position in which the backstop 45 extends obliquely upward from the collapsed boom 16 (lower boom 16A) so that the backstop 45 can restrict the collapse of the boom 16 backward by the backstop abutment portion 451S of the backstop 45 abutting against the backstop receiving portion 121 of the upper rotating body 12 as the boom 16 stands up from the collapsed state (see FIG. 4). On the other hand, the storage position is a position in which the backstop abutment portion 451S of the backstop 45 is positioned closer to the lower boom 16A (boom 16) than in the support position. Therefore, as shown in Figures 2 and 4, the backstop lifting device 60 is positioned in the space between the backstop 45 and the first main pipe 161 of the lower boom 16A.

Referring to FIG. 4, the backstop lifting device 60 has a first arm 61, a second arm 62, a pair of left and right stoppers 63, and a lifting cylinder 66.

The first arm 61 and the second arm 62 are connected so as to be able to bend and extend, and one end of the first arm 61 is rotatably connected to the backstop connection portion 451T of the backstop 45. Meanwhile, the other end of the first arm 61 and one end of the second arm 62 are rotatably connected to each other. The other end of the second arm 62 is rotatably connected to the first main pipe 161 of the lower boom 16A.

The lift cylinder 66 is disposed on the top of the second arm 62, as shown in FIG. 4. The lift cylinder 66 is composed of an extendable hydraulic cylinder. When the lift cylinder 66 extends, the tip of the lift cylinder 66 pushes up the first arm 61, causing it to stand up against the second arm 62. As a result, as shown in FIG. 4, the backstop 45 is changed to the support position. On the other hand, when the lift cylinder 66 contracts, the first arm 61 and the second arm 62 are bent under the weight of the backstop 45, and the backstop 45 is changed to the storage position, as shown in FIG. 2.

The pair of left and right stoppers 63 connect the first arm 61 and the second arm 62 to each other when the backstop 45 is in the supporting position, and hold the backstop 45 in the supporting position. The pair of left and right stoppers 63 are detachable from the first arm 61 and the second arm 62.

Figure 6 is a schematic diagram showing the hydraulic circuit of the backstop lifting device 60 in the crane 10 according to this embodiment. As shown in Figure 6, the cylinder rod 662 of the lifting cylinder 66 divides the internal space of the cylinder body 661 into a head chamber 66A and a rod chamber 66B and has a piston portion 66P that is movable within the internal space. The backstop lifting device 60 also has a hydraulic pump 71, a relief valve 71R, and a directional control valve 72.

The hydraulic pump 71 is capable of discharging hydraulic oil supplied to the head chamber 66A and the rod chamber 66B of the cylinder rod 662.

The directional control valve 72 is disposed between the hydraulic pump 71 and the cylinder body 661. The directional control valve 72 can be switched between an extension position, a contraction position, and a neutral position by a pair of solenoids receiving a command signal from the control unit 80. Specifically, as shown in FIG. 6, the directional control valve 72 is switched to the extension position by an operator turning on a switch 801 connected to the control unit 80, while the directional control valve 72 is switched to the contraction position by an operator turning on a switch 802. In the extension position (the position on the right side in FIG. 6), the directional control valve 72 supplies hydraulic oil discharged from the hydraulic pump 71 to the head chamber 66A and guides hydraulic oil discharged from the rod chamber 66B to a tank T, thereby extending the cylinder rod 662 relative to the cylinder body 661. Furthermore, in the contraction position (the position on the right side in FIG. 6), the directional control valve 72 supplies the hydraulic oil discharged from the hydraulic pump 71 to the rod chamber 66B and guides the hydraulic oil discharged from the head chamber 66A to the tank T, thereby contracting the cylinder rod 662 relative to the cylinder body 661. In the neutral position (the center position in FIG. 6) where switches 801 and 802 are turned OFF, the directional control valve 72 prevents the hydraulic oil discharged from the hydraulic pump 71 from being supplied to the head chamber 66A and the rod chamber 66B, and prevents the hydraulic oil from being discharged from the head chamber 66A and the rod chamber 66B. When the directional control valve 72 is set to the neutral position, some of the hydraulic oil in the head chamber 66A and the rod chamber 66B may leak out from some of the piping of the hydraulic circuit, but the cylinder rod 662 can be maintained in the most extended state relative to the cylinder body 661 for at least a certain period of time, in other words, the first arm 61 and the second arm 62 can be maintained at the first angle and the stopper 63 can be attached and detached. When the directional control valve 72 is switched to the neutral position (the center position in FIG. 6), the hydraulic oil discharged from the hydraulic pump 71 is discharged directly into the tank.

Figure 7 is a block diagram of the crane 10 according to this embodiment. Note that the block diagram shown in Figure 7 shows a part of the configuration that controls the operation of the crane 10.

Referring to FIG. 7, the crane 10 further includes a boom hoisting drive unit 31, a control unit 80, a boom operation unit 91, a lifting operation unit 92, a boom hoisting angle detection unit 93, a display unit 94, and an alarm unit 95.

The boom hoisting drive unit 31 is capable of receiving a hoisting command signal and raising or lowering the boom 16 relative to the upper rotating body 12 in response to the hoisting command signal. In addition to the boom hoisting winch 30 and boom hoisting rope 22 described above, the boom hoisting drive unit 31 includes a hydraulic circuit such as a hydraulic pump and control valve (not shown) for rotating the boom hoisting winch 30. The hoisting command signal to the boom hoisting drive unit 31 is input from a drive control unit 810 (described below) of the control unit 80.

The control unit 80 controls various operations of the crane 10, and FIG. 7 shows in particular the control related to the raising and lowering operation of the boom 16, the raising and lowering operation of the backstop 45, and the control to prevent interference between the backstop 45 and the upper rotating body 12 during the raising and lowering operation of the boom 16.

The boom operation unit 91 is disposed in the cab of the crane 10 and includes an operation lever that is operated by the operator. The boom operation unit 91 receives operations for raising and lowering the boom 16.

The lifting/lowering operation unit 92 is disposed in the cab of the crane 10 and is operated by the operator. In this embodiment, the lifting/lowering operation unit 92 is composed of switches 801 and 802 in FIG. 6. The lifting/lowering operation unit 92 accepts operations to raise and lower the backstop 45, i.e., to change the position of the backstop 45 between the aforementioned support position and the storage position.

The boom hoist angle detection unit 93 detects the boom hoist angle (angle θ in FIG. 10), which is the relative angle of the boom 16 with respect to the upper rotating body 12. The boom hoist angle detection unit 93 is composed of a goniometer provided on the boom foot 16S or a rotation goniometer provided on the boom hoist winch 30. As an example, in this embodiment, the boom hoist angle θ is the angle of the center line 16L of the boom 16 with respect to the horizontal line CL passing through the boom foot 16S (see FIG. 10). Information on the boom hoist angle detected by the boom hoist angle detection unit 93 is input to the control unit 80.

The display unit 94 is disposed inside the cab of the crane 10 and displays various operational information of the crane 10. Similarly, the alarm unit 95 is disposed inside or outside the cab of the crane 10 and generates alarm sounds to notify the operator of various conditions of the crane 10.

Figure 8 is an enlarged side view of the backstop 45 of the crane 10 in the stored position according to this embodiment. Figure 9 is an enlarged side view of the backstop 45 of the crane 10 in the supported position. The boom 16 of the crane 10 further has a pair of left and right arm support parts 621 provided for the pair of left and right backstops 45, respectively, a pair of left and right limit switches 622 (position detection parts), and a pair of left and right strikers 623. Note that since the structures of these pairs of left and right are the same, the structure of the right side will be described below.

The arm support 621 is provided on the first main pipe 161 of the boom 16 and rotatably supports the base end of the second arm 62. The limit switch 622 is fixed to the arm support 621 and is capable of detecting that the backstop 45 is in the support position. The limit switch 622 has a switch body (not shown) and a pressed part that can be moved in and out of the switch body. The striker 623 is fixed to the base end of the second arm 62. As shown in FIG. 8, when the backstop 45 is in the storage position by the backstop lifting device 60, the striker 623 is disposed away from the pressed part of the limit switch 622, so that the limit switch 622 inputs a LOW signal to the control unit 80. On the other hand, as shown in FIG. 9, when the backstop 45 is placed in the supporting position by the backstop lifting device 60, the striker 623 presses the pressed portion of the limit switch 622 from above, causing the limit switch 622 to input a HIGH signal to the control unit 80. As a result, the control unit 80 can recognize that the backstop 45 is held in the supporting position. Note that the control unit 80 may determine that the backstop 45 is in the stored position if a HIGH signal is not input from the limit switch 622.

The manner in which the attitude detection unit of the present invention, represented by the limit switch 622, detects the attitude of the backstop 45 is not limited to the above manner (FIGS. 8 and 9). For example, the limit switch structure shown in FIG. 8 and FIG. 9 may be disposed on the backstop 45 side. Also, an angle meter (not shown) may be installed at the portion where the backstop 45 is attached to the lower boom 16A, and the attitude of the backstop 45 may be determined according to the detection result of the angle meter. Also, the attitude of the backstop 45 may be detected by detecting the presence or absence of a fixing member (pin) that fixes the backstop 45 to the storage attitude and the support attitude, respectively, using a proximity sensor or the like. Furthermore, the attitude of the backstop 45 detected by the attitude detection unit may be at least one of the support attitude and the storage attitude. In an embodiment in which the attitude detection unit detects only the support attitude of the backstop 45, if the attitude detection unit does not detect the support attitude of the backstop 45, it may be determined that the backstop 45 is in the storage attitude. Also, in a mode in which the posture detection unit detects only the storage posture of the backstop 45, the backstop 45 may be determined to be in the support posture when the posture detection unit does not detect the storage posture of the backstop 45. It is preferable that the posture detection unit is capable of detecting both the support posture and the storage posture of the backstop 45. In this case, the posture detection unit is able to detect that the backstop 45 is held in an intermediate posture between the support posture and the storage posture against the operator's intention, which prevents the backstop 45 from interfering with surrounding members and enhances safety.

The control unit 80 described above is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, and a RAM (Random Access Memory) that is used as a working area for the CPU. The control unit 80 is also connected to the boom hoisting drive unit 31, the lifting cylinder 66, the boom operation unit 91, the lifting operation unit 92, the boom hoisting angle detection unit 93, the limit switch 622, the display unit 94, and the notification unit 95. The control unit 80 functions as a drive control unit 810, a hoisting permission unit 820 (hoisting prevention unit), a determination unit 830, and a memory unit 840 by the CPU executing the control program stored in the ROM.

The drive control unit 810 inputs various command signals to the boom hoisting drive unit 31 and the lifting cylinder 66 to perform the lifting operation of the boom 16 and the lifting and lowering operation of the backstop 45. The drive control unit 810 inputs the lifting command signal to the boom hoisting drive unit 31 so that the boom 16 is raised and lowered at a drive speed corresponding to the amount of operation in the direction (raising direction, lowering direction) input to the boom operation unit 91. The drive control unit 810 also inputs command signals to a pair of solenoids of the directional control valve 72 in FIG. 6 in response to instruction information input to the lifting and lowering operation unit 92, i.e., an instruction to raise the backstop 45 from the storage position to the support position and an instruction to lower the backstop 45 from the support position to the storage position, thereby expanding and contracting the lifting cylinder 66 and raising and lowering the backstop 45.

The hoisting permission unit 820 has the function of permitting or preventing the hoisting operation of the boom 16 by the boom hoisting drive unit 31 depending on information regarding the posture of the backstop 45 detected by the limit switch 622 and the boom angle detected by the boom hoisting angle detection unit 93.

The determination unit 830 performs various determination processes in the boom 16 raising/lowering permission operation performed by the raising/lowering permission unit 820.

The memory unit 840 pre-stores various thresholds, parameters, etc. referenced by the drive control unit 810, the undulation permission unit 820, and the determination unit 830.

Figure 10 is a side view showing how the boom 16 is raised in the crane 10 according to this embodiment. Figure 11 is a plan view showing how the boom 16 is raised in the crane 10. Figure 12 is an enlarged side view showing how the tip of the backstop 45 interferes with the upper rotating body 12, as viewed along arrows XII-XII in Figure 11. Note that Figures 10 and 11 only show the lower boom 16A of the boom 16, and the other parts are not shown.

The rotating frame 120 of the upper rotating body 12 has a pair of left and right gantry support parts 210 (Figs. 10 to 12). The gantry support parts 210 are arranged rearward of the boom base end 16P of the boom 16 and forward of the backstop receiving part 121 (Fig. 5). The gantry support parts 210 rotatably support the base ends (gantry base ends) of a pair of left and right tension members of the gantry 21. The enlarged side view of Fig. 12 shows the rotation axis 21S of the tension members. As shown in Fig. 11, the pair of gantry support parts 210 are arranged so as to overlap (overlap) the pair of backstops 45 when viewed from the front-rear direction.

Referring to FIG. 10, when the crane 10 is assembled and disassembled, the boom 16 can be lowered relative to the upper rotating body 12 until the boom hoisting angle θ becomes the maximum lowering angle. The maximum lowering angle is the relative angle of the boom 16 with respect to the upper rotating body 12 when the boom 16 is in the maximum lowering state, so that the center line 16L of the boom 16 extends forward and downward from the boom foot 16S (boom rotation center axis). In FIG. 10, the state in which the tip of the boom 16 (not shown) abuts on the ground G corresponds to the maximum lowering angle. In addition, when the crane 10 is transported, the member of the boom 16 on the tip side of the lower boom 16A is detached from the lower boom 16A as shown in FIG. 10. In this case, the state in which the tip of the lower boom 16A in FIG. 10 abuts on the ground G (or the loading platform T of the transport vehicle) corresponds to the maximum lowering angle.

When the boom 16 or the lower boom 16A is raised from a state in which it is lowered relative to the upper rotating body 12 (the state in which the boom is lowered) as described above, the backstop 45 is set in a support position in advance. On the other hand, if the boom 16 (lower boom 16A) is raised with the backstop 45 in the stored position, as shown in FIG. 12, the backstop abutment parts 451S of the pair of left and right backstops 45 interfere with the pair of left and right gantry support parts 210, and at least one of the backstop abutment parts 451S and the gantry support parts 210 may be broken or damaged. In particular, if the backstop abutment parts 451S are damaged, the backstop abutment parts 451S will not be able to normally abut against the backstop receiving parts 121 with which they should abut, making it difficult for the backstop 45 to support the boom 16 from the rear. In addition, as mentioned above, the backstop 45 is extended to its free length by the biasing force of the backstop spring 453 when in an unloaded state, so a complex structure would be required to shorten the length of the backstop 45 in the stored position to prevent the above-mentioned interference.

In order to solve the above problems, in this embodiment, the control unit 80 has a function to restrict the hoisting operation of the boom 16. Next, a control flow until the hoisting operation of the boom 16 is permitted or blocked by the hoisting permission unit 820 in this embodiment will be described. FIG. 13 is a flowchart of the raising operation control of the boom 16 in the crane 10 according to this embodiment. Here, an example will be described in which the lower boom 16A is raised upward from the state shown in FIG. 10 in which the tip of the lower boom 16A is in contact with the ground G. In this case, if the boom hoisting angle θ is defined as zero degrees when the horizontal line CL passing through the boom foot 16S in FIG. 10 overlaps with the center line 16L of the boom 16, the boom hoisting angle θ when the tip of the lower boom 16A is in contact with the ground G is, for example, -10 degrees.

When this control is started, the determination unit 830 of the control unit 80 determines whether or not a boom hoisting operation (here, a standing operation) of the boom 16 has been input through the boom operation unit 91 (step S1 in FIG. 13). If a standing operation of the boom 16 has not been input, the determination of step S1 is repeated until a standing operation is input. On the other hand, if a standing operation of the boom 16 has been input in step S1, the boom hoisting angle detection unit 93 measures the boom hoisting angle θ of the boom 16 (lower boom 16A) (step S2). Note that the boom hoisting angle detection unit 93 may always obtain the boom hoisting angle θ, and the control unit 80 may obtain the detection result in step S2.

Next, the determination unit 830 determines whether the boom hoisting angle θ acquired in step S2 is within a preset work angle range (step S3). The work angle range corresponds to the range of the boom hoisting angle θ for performing normal work on the crane 10. That is, when the boom 16 is raised diagonally upward relative to the upper rotating body 12 and the boom hoisting angle θ is within the preset work angle range, the boom 16 can support a load connected to the boom tip 16Q. Note that even when a jib (not shown) is connected to the tip of the boom 16 and a load is suspended from the tip of the jib, the boom 16 will support the load as a result, and the work angle range is set in the same way. As an example, the work angle range in this embodiment is set to a range of +30 degrees to +80 degrees, assuming that the boom hoisting angle θ is zero degrees when the horizontal line CL and the center line 16L of the boom 16 overlap in FIG. 10.

In step S3, if the current boom hoisting angle θ is within the working angle range (NO in step S3), as shown in Figures 1 and 5, the backstop 45 is positioned away from the gantry support part 210, and there is no risk of interference between the backstop abutment part 451S and the gantry support part 210, so the hoisting permission part 820 permits (continues) the raising operation of the boom 16 in response to the operation input to the boom operation part 91 (step S7).

On the other hand, in step S3, if the current boom hoisting angle θ is not within the working angle range (YES in step S3), the determination unit 830 receives the output signal from the limit switch 622 and determines whether the backstop 45 is in the supporting position (step S4). If the backstop 45 is not in the supporting position (NO in step S4), the determination unit 830 determines whether the current boom hoisting angle θ is within the interference prevention angle range (step S5). Note that even if the backstop 45 is in the supporting position (YES in step S4), there is no risk of interference between the backstop abutment portion 451S and the gantry support portion 210, so the hoisting permission unit 820 permits (continues) the raising operation of the boom 16 in accordance with the operation input to the boom operation unit 91 (step S7).

The interference prevention angle range is a preset angle range for the boom hoisting angle θ to guard against (prevent) interference between the backstop abutment portion 451S and the gantry support portion 210 (a portion of the upper rotating body 12 other than the backstop receiving portion 121) when the backstop 45 is in the stored position, as shown in FIG. 12. In other words, if the boom hoisting angle θ is not included in the interference prevention angle range, there is no risk of interference between the backstop abutment portion 451S and the gantry support portion 210. In this embodiment, the interference prevention angle range is set to a range in which the boom hoisting angle θ is -5 degrees or more and +5 degrees or less. In other words, the lower limit of the interference prevention angle range (lower limit angle, -5 degrees) is set to an angle larger than the maximum lowering angle (-10 degrees) described above. Also, the upper limit of the interference prevention angle range (upper limit angle, +5 degrees) is set to an angle larger than the lower limit and smaller than the working angle range described above.

Therefore, in step S5, if the current boom hoisting angle θ is not within the interference prevention angle range (NO in step S5), the hoisting permission unit 820 permits (continues) the raising operation of the boom 16 in accordance with the operation input to the boom operation unit 91 (step S7).

On the other hand, in step S5, if the current boom hoist angle θ is within the interference prevention angle range (YES in step S5), the hoist permission unit 820 inputs a forced stop command signal to the boom hoist drive unit 31 to forcibly stop the raising of the boom 16, regardless of the operation input to the boom operation unit 91, and automatically stops the raising of the boom 16 (step S6). Therefore, in the state shown in Figure 10, the raising operation starts when the boom hoist angle θ is -10 degrees, and when the boom hoist angle θ reaches -5 degrees, the raising operation of the lower boom 16A automatically stops.

In addition, in this embodiment, when the raising operation of the lower boom 16A is automatically stopped in step S6, the raising/lowering permission unit 820 inputs information (alarm information) to the display unit 94 to notify that there is a possibility of interference between the backstop abutment portion 451S and the gantry support portion 210, and causes the display unit 94 to display the information. Similarly, the raising/lowering permission unit 820 inputs the information to the notification unit 95, and notifies the operator of the possibility of interference by a buzzer sound or the like.

The operator recognizes that the lower boom 16A has automatically stopped and that the lower boom 16A has been raised with the backstop 45 in the stored position based on the information notified by the display unit 94 and the notification unit 95. Therefore, the operator interrupts the operation of raising the lower boom 16A through the boom operation unit 91 and operates the lift operation unit 92 to change the position of the backstop 45 from the stored position to the supporting position.

When the backstop 45 is in the support position as described above, the backstop abutment portion 451S is positioned above the gantry support portion 210 at a distance, so there is no risk of the two interfering with each other. Therefore, when the worker operates the boom operation unit 91 again to resume the raising operation of the lower boom 16A, the determination unit 830 determines YES in step S4 of FIG. 13, allowing the raising operation to continue (step S7).

As described above, in this embodiment, the crane 10 has a control unit 80 including a hoisting permission unit 820. When the boom hoisting angle θ, which is the relative angle of the boom 16 with respect to the upper rotating body 12, is within a preset interference prevention angle range to prevent interference between the backstop abutment portion 451S and the gantry support portion 210, based on the detection result of the limit switch 622, the hoisting permission unit 820 prevents the boom hoisting operation of the boom 16 by the boom hoisting drive unit 31 regardless of the input of a hoisting command signal to the boom hoisting drive unit 31. On the other hand, the hoisting permission unit 820 allows the boom hoisting operation of the boom 16 by the boom hoisting drive unit 31 when the backstop 45 is in the support position based on the detection result of the limit switch 622, regardless of the magnitude of the boom hoisting angle θ.

With this configuration, even if the boom 16 is raised or lowered while the backstop 45 is in the stored position, if the boom hoisting angle θ is within the interference prevention angle range, the hoisting permission unit 820 can forcibly prevent the boom 16 from being hoisted, thereby preventing interference between the backstop abutment portion 451S and a portion of the upper rotating body 12 other than the backstop receiving portion 121, such as the gantry support portion 210.

The above-described control is effective when the crane 10 is transported by a transport vehicle with the lower boom 16A attached to the upper rotating body 12, as shown in FIG. 10. In such a case, when the transport vehicle arrives at the work site, the lower boom 16A, whose tip is in contact with the loading platform T, is slightly raised, and the lower running body 14 is caused to run, thereby moving the crane 10 from the loading platform T to the ground G. At this time, if the worker raises the lower boom 16A while the backstop 45 is in the stored position, there is a possibility that interference will occur as described above. Therefore, the raising and lowering permission unit 820 can be used to prevent the raising operation, thereby preventing such interference from occurring.

In addition, even when the lower boom 16A is separated from the upper rotating body 12 during transportation as described above and the boom 16 is attached to the upper rotating body 12 at the work site, interference between the backstop abutment portion 451S of the backstop 45 in the stored position and the crane body such as the gantry support portion 210 can be effectively prevented.

Furthermore, in the above description, the lower boom 16A is raised from the ground G or the loading platform T as an example. However, even if the boom 16 is raised to a predetermined angle greater than the interference prevention angle range, the backstop 45 is in the stored position, and the boom 16 is lowered, the backstop abutment portion 451S may approach the gantry support portion 210 from above, causing interference between them. In such a case, when the boom hoisting angle θ reaches the upper limit of the interference prevention angle range, the hoisting permission portion 820 automatically stops the lowering operation of the boom 16 to prevent the above-mentioned interference. Then, the operator can safely lower the boom 16 (lower boom 16A) to the maximum lowering angle after changing the position of the backstop 45 to the support position.

In addition, in this embodiment, when the boom hoisting drive unit 31 raises the boom 16 from the maximum hoisting angle with the backstop 45 in the stored position and the boom hoisting angle θ reaches the lower limit angle of the interference prevention angle range, the hoisting permission unit 820 inputs a forced stop signal to the boom hoisting drive unit 31 to forcibly stop the raising operation of the boom 16.

With this configuration, even if the boom 16 is raised from the maximum hoisting angle with the backstop 45 in the stored position, when the boom hoisting angle reaches the lower limit angle of the interference prevention angle range, the hoisting permission unit 820 forcibly stops the hoisting operation of the boom 16, thereby preventing interference between the backstop abutment unit 451S and the front part of the upper rotating body 12 (gantry support unit 210). In particular, even if an operator raises the boom 16 without first changing the position of the backstop 45 to the support position during the assembly work of the crane 10, the above-mentioned interference can be reliably prevented.

Furthermore, in this embodiment, when the boom hoisting angle θ is within the working angle range, the hoisting permission unit 820 allows the boom hoisting drive unit 31 to perform the hoisting operation of the boom 16 regardless of the magnitude of the boom hoisting angle θ.

With this configuration, when the boom hoisting angle θ is within the working angle range, the hoisting permission unit 820 does not prevent the hoisting operation of the boom 16. Therefore, even if the limit switch 622 erroneously detects the position of the backstop 45, it is possible to prevent the boom 16 from stopping against the operator's intention during normal operation of the crane 10.

In this embodiment, the crane 10 is also equipped with a display unit 94 and an alarm unit 95 (both of which are alarm devices). The alarm device issues a warning to the operator when the boom hoisting angle θ falls within the interference prevention angle range with the backstop 45 in the stored position based on the detection result of the limit switch 622.

With this configuration, by notifying the operator that there is a risk of interference between the backstop abutment portion 451S and the upper rotating body 12, the operator can be made aware of the reason why the raising and lowering of the boom 16 has stopped, and the operator can be less likely to raise and lower the boom 16 while keeping the backstop 45 in the stored position during subsequent work. The above notification may also be made immediately before the automatic stop by the raising and lowering permission unit 820.

In addition, in this embodiment, the crane 10 is equipped with a backstop lifting device 60 (backstop position change unit) that can change the position of the backstop 45 between the support position and the storage position by rotating the backstop 45 around the reference rotation center axis.

With this configuration, when the hoisting permission unit 820 forcibly stops the hoisting operation of the boom 16, the backstop lifting device 60 can change the position of the backstop 45 from the stored position to the support position, so that the hoisting operation of the boom 16 can be quickly resumed.

In this embodiment, the crane 10 includes a gantry 21, and the rotating frame 120 of the upper rotating body 12 includes a gantry support portion 210. The interference prevention angle range is set so as to prevent the backstop abutment portion 451S and the gantry support portion 210 from interfering with each other when the boom 16 is raised with the backstop 45 in the stored position.

With this configuration, even if the gantry 21 is disposed behind the boom 16 and the gantry support part 210 for supporting the gantry 21 is disposed in a position in front of the backstop receiving part 121 that is likely to interfere with the backstop abutment part 451S, interference between the backstop abutment part 451S and the gantry support part 210 can be prevented in advance.

Furthermore, in this embodiment, the height of the backstop 45 in the support position relative to the boom base end 16P is set so that when the backstop 45 is in the support position and the boom 16 (lower boom 16A) is raised from its collapsed state, the backstop abutment portion 451S moves rearward above the portion of the upper rotating body 12 that is forward of the backstop receiving portion 121 and then abuts against the backstop receiving portion 121.

With this configuration, when the backstop 45 is in the support position, the backstop abutment portion 451S can pass above the front portion of the upper rotating body 12, so interference between the backstop abutment portion 451S and the upper rotating body 12 can be reliably prevented.

The crane 10 according to one embodiment of the present invention has been described above. However, the present invention is not limited to these embodiments. The following modified embodiments are possible with the present invention.

(1) In the above embodiment, the gantry support 210 is used as the part with which the backstop abutment portion 451S may interfere, but the present invention is not limited to this. The part with which the backstop abutment portion 451S may interfere may be another part other than the backstop receiving portion 121, such as the front end portion of the upper rotating body 12.

(2) In the above embodiment, the crane 10 is described as having the backstop lifting device 60, but the present invention is not limited to this. The crane 10 may not have the backstop lifting device 60, and the position of the backstop 45 may be switched between a support position and a storage position by an operator. In addition, the structure of the backstop lifting device 60 is not limited to the bending and extending structure including the first arm 61 and the second arm 62 as in the above embodiment, but may be a cylinder structure or a rod-shaped support member that supports the backstop 45 along a direction perpendicular to the longitudinal direction of the backstop 45.

(3) In addition, while the above embodiment has been described using the crane 10 shown in FIG. 1, the present invention is not limited to this and can be applied to cranes with other structures. In other words, the crane to which the present invention is applied may be one equipped with a lattice mast or box mast instead of the gantry 21. Also, it may be one equipped with a jib or strut attached to the tip of the boom. In addition, while the above embodiment has been described using a backstop for the boom, the present invention can also be applied to backstops equipped on the mast (lattice mast), struts (rear strut, front strut), and jib.

10 Crane 12 Upper rotating body (crane body)
120 Swivel frame 121 Backstop receiving portion 16 Boom 160 Lower frame 161 First main pipe 16A Lower boom 16P Boom base end portion 16Q Boom tip portion 16S Boom foot 21 Gantry 210 Gantry support portion 21S Gantry fulcrum portion 31 Boom hoisting drive portion 45 Backstop 451 Backstop lower portion 451S Backstop abutment portion (backstop tip portion)
452 Backstop upper part 452S Backstop fulcrum part (backstop base end part)
453 Backstop spring 60 Backstop lifting device 61 First arm 62 Second arm 621 Arm support part 622 Limit switch (posture detection part)
623 Striker 63 Stopper 66 Lifting cylinder 80 Control unit 810 Drive control unit 820 Raising/lowering permission unit (raising/lowering prevention unit)
830 Determination unit 840 Memory unit 91 Boom operation unit 92 Lifting operation unit 93 Boom hoisting angle detection unit 94 Display unit 95 Notification unit G Ground T Loading platform

Claims (6)

A crane body having a backstop receiving portion facing upward;
A boom including a boom base end supported on the crane body forward of the backstop receiving portion so as to be rotatable in a hoisting direction about a horizontal boom rotation central axis, and a boom tip end opposite to the boom base end;
a boom hoisting drive unit that receives a hoist command signal and is capable of raising and lowering the boom relative to the crane body in response to the hoist command signal;
a backstop including a backstop base end supported rotatably about a reference rotation center axis parallel to the boom rotation center axis in a portion of the boom closer to the boom tip than the boom base end, and a backstop tip end disposed on the opposite side to the backstop base end, the backstop being capable of changing its position between a support position and a storage position by rotating about the reference rotation center axis, the support position being a position in which the backstop extends obliquely upward from the boom in the collapsed state in which the boom is collapsed relative to the crane body, so that the backstop can restrict the boom from collapsing backward by the backstop tip end abutting on the backstop receiving portion of the crane body as the boom rises from a collapsed state in which the boom is collapsed relative to the crane body, and the storage position being a position in which the backstop tip of the backstop is disposed closer to the boom than the support position;
A posture detection unit capable of detecting that the backstop is in at least one of the support posture and the storage posture;
a boom hoist prevention unit that prevents the boom hoisting operation by the boom hoist drive unit regardless of input of the hoist command signal when a boom hoist angle, which is the relative angle of the boom to the crane body, is within a preset interference prevention angle range to prevent interference between the tip of the backstop and a portion of the crane body other than the backstop receiving portion, when the backstop is in the stored posture;
Equipped with
the boom can be lowered forward relative to the crane body until the boom hoisting angle reaches a maximum lowering angle, and the maximum lowering angle is a relative angle of the boom with respect to the crane body when the boom is in a state where it is lowered to the maximum such that the center line of the boom extends forward and downward from the boom rotation central axis,
The interference prevention angle range has a lower limit angle greater than the maximum lowering angle, which is set to prevent the tip of the backstop from interfering with the front part of the crane body,
the boom hoisting prevention unit inputs a forced stop signal to the boom hoisting drive unit to forcibly stop the boom raising operation when the boom is raised from the maximum hoisting angle by the boom hoisting drive unit with the backstop in the stored position and the boom hoisting angle reaches the lower limit angle . The boom is capable of supporting a load connected to the boom tip when the boom is raised relative to the crane body and the boom hoisting angle is within a preset working angle range,
the interference prevention angle range has an upper limit angle larger than the lower limit angle, and the upper limit angle is set to an angle smaller than the work angle range,
2. The crane according to claim 1, wherein the boom hoist prevention section allows the boom hoisting operation of the boom by the boom hoist drive section regardless of the magnitude of the boom hoist angle when the boom hoist angle is within the working angle range. A crane body having a backstop receiving portion facing upward;
A boom including a boom base end supported on the crane body forward of the backstop receiving portion so as to be rotatable in a hoisting direction about a horizontal boom rotation central axis, and a boom tip end opposite to the boom base end;
a boom hoisting drive unit that receives a hoist command signal and is capable of raising and lowering the boom relative to the crane body in response to the hoist command signal;
a backstop including a backstop base end supported rotatably about a reference rotation center axis parallel to the boom rotation center axis in a portion of the boom closer to the boom tip than the boom base end, and a backstop tip end disposed on the opposite side to the backstop base end, the backstop being capable of changing its position between a support position and a storage position by rotating about the reference rotation center axis, the support position being a position in which the backstop extends obliquely upward from the boom in the collapsed state in which the boom is collapsed relative to the crane body, so that the backstop can restrict the boom from collapsing backward by the backstop tip end abutting on the backstop receiving portion of the crane body as the boom rises from a collapsed state in which the boom is collapsed relative to the crane body, and the storage position being a position in which the backstop tip of the backstop is disposed closer to the boom than the support position;
A posture detection unit capable of detecting that the backstop is in at least one of the support posture and the storage posture;
a boom hoist prevention unit that prevents the boom hoisting operation by the boom hoist drive unit regardless of input of the hoist command signal when a boom hoist angle, which is the relative angle of the boom to the crane body, is within a preset interference prevention angle range to prevent interference between the tip of the backstop and a portion of the crane body other than the backstop receiving portion, when the backstop is in the stored posture;
Equipped with
The crane further includes an alarm device that issues warning information to an operator when the boom hoisting angle falls within the interference prevention angle range with the backstop in the stored posture. The crane according to any one of claims 1 to 3, further comprising a backstop attitude change unit capable of changing the attitude of the backstop between the support attitude and the stored attitude by rotating the backstop around the reference rotation center axis . A crane body having a backstop receiving portion facing upward;
A boom including a boom base end supported on the crane body forward of the backstop receiving portion so as to be rotatable in a hoisting direction about a horizontal boom rotation central axis, and a boom tip end opposite to the boom base end;
a boom hoisting drive unit that receives a hoist command signal and is capable of raising and lowering the boom relative to the crane body in response to the hoist command signal;
a backstop including a backstop base end supported rotatably about a reference rotation center axis parallel to the boom rotation center axis in a portion of the boom closer to the boom tip than the boom base end, and a backstop tip end disposed on the opposite side to the backstop base end, the backstop being capable of changing its position between a support position and a storage position by rotating about the reference rotation center axis, the support position being a position in which the backstop extends obliquely upward from the boom in the collapsed state in which the boom is collapsed relative to the crane body, so that the backstop can restrict the boom from collapsing backward by the backstop tip end abutting on the backstop receiving portion of the crane body as the boom rises from a collapsed state in which the boom is collapsed relative to the crane body, and the storage position being a position in which the backstop tip of the backstop is disposed closer to the boom than the support position;
A posture detection unit capable of detecting that the backstop is in at least one of the support posture and the storage posture;
a boom hoist prevention unit that prevents the boom hoisting operation by the boom hoist drive unit regardless of input of the hoist command signal when a boom hoist angle, which is the relative angle of the boom to the crane body, is within a preset interference prevention angle range to prevent interference between the tip of the backstop and a portion of the crane body other than the backstop receiving portion, when the backstop is in the stored posture;
Equipped with
The crane further includes a gantry having a gantry base end supported by the crane body at a rear of the boom base end and in front of the backstop receiving portion, and supporting the boom so that the boom can be raised and lowered.
The crane body further includes a gantry support portion that is arranged so as to overlap the backstop when viewed from the front-rear direction and supports the gantry base end portion,
the interference prevention angle range is set so as to prevent the tip of the backstop and the gantry support from interfering with each other when the boom is raised with the backstop in the stored position. 6. The crane according to claim 1, wherein a height of the backstop in the supporting posture relative to the boom base end is set so that, when the backstop is in the supporting posture and the boom is raised from the laid-down state, the tip end of the backstop moves rearward above a portion of the crane body that is forward of the backstop receiving portion and then comes into contact with the backstop receiving portion.

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