crane

Abstract

To prevent interference between a backstop supported by a boom so that it can be hoisted and a crane body when the boom is hoisted in the crane.SOLUTION: A crane 10 includes an upper rotating body 12, a boom 16, a boom hoisting drive unit 31, a backstop 45 whose posture can be changed between a storage posture and a support posture, a limit switch 622 for detecting the posture of the backstop 45, and a hoist permitting unit 820. With the backstop 45 being in the storage posture, the hoist permitting unit 820 forcibly prevents the hoisting operation of the boom 16 by the boom hoisting drive unit 31 when a boom hoisting angle θ, which is the angle of the boom 16 relative to the upper rotating body 12, is within an interference prevention angle range set in advance to prevent a backstop contacting unit 451S and a part of the upper rotating body 12 different from a backstop receiving unit 121 (a gantry support unit 210) from interfering with each other.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a crane. [Background technology]

[0002] Conventionally, cranes including a crane body and a boom are known. The boom is supported by the crane body so as to be able to be raised and lowered around a horizontal rotation axis. In addition, as such a crane, one is known that further includes a pair of left and right backstops interposed between the boom and the crane body to prevent the boom from tipping backward. 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 surface 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 comes into contact with 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., the boom from tipping backward.

[0003] On the other hand, when the crane is transported or stored, each backstop is rotated about its base end as a fulcrum to be placed in a stored position overlapping the back of the boom, thereby reducing the space required for the boom on the transport vehicle or in the storage area.

[0004] Patent Document 1 discloses a backstop that can be separated into a base end support shaft rotatably supported on the crane body and a tip end support shaft 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. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-290782 A Summary of the Invention [Problem to be solved by the invention]

[0006] The technology described in Patent Document 1 has a problem in that 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.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object 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. [Means for solving the problem]

[0008] A crane according to an 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 on the crane body 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 is capable of receiving a hoisting command signal and 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 supporting posture is a posture in which the backstop extends obliquely 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 in which the boom is collapsed relative to the crane body. The storing posture is a posture in which the backstop tip of the backstop is disposed closer to the boom than the supporting posture. The posture detection unit is capable of detecting that the backstop is in at least one of the supporting posture and the storing posture. The boom hoisting prevention unit prevents the boom hoisting operation by the boom hoisting drive unit regardless of the input of the hoist command signal when the backstop is in the storing posture and a boom hoist angle, which is the relative angle of the boom with respect 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.

[0009] With this configuration, even if the boom is raised or lowered with the backstop 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 hoisting movement, thereby preventing interference between the tip of the backstop and the crane body.

[0010] In the above configuration, it is desirable that the boom can be lowered forward relative to the crane body until the boom hoist angle reaches the maximum hoisting angle, the maximum hoisting angle being the relative angle of the boom with respect to the crane body when the boom is in the maximum hoisted state so that the centre line of the boom extends forward and downward from the boom rotation centre axis, 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 the boom hoist prevention unit inputs a forced stop signal to the boom hoist drive unit to forcibly stop the boom raising operation when the boom is raised from the maximum hoisting angle by the boom hoist drive unit with the backstop in the stored position and the boom hoist angle reaches the lower limit angle.

[0011] With this configuration, even if the boom is raised from the maximum hoisting angle with the backstop in the stored position, the boom hoist prevention part forcibly stops the boom hoisting operation when the boom hoist angle reaches the lower limit of the interference prevention angle range, 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 supporting position during assembling the crane, the above-mentioned interference can be reliably prevented.

[0012] In the above configuration, it is desirable that the boom is capable of supporting a load connected to the boom tip when the boom is upright relative to the crane body and the boom hoist angle is within a predetermined 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 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 work angle range.

[0013] According to this configuration, when the boom hoisting angle is within the working angle range, the boom hoisting prevention section does not prevent the boom hoisting operation, so even if the attitude detection section erroneously detects the attitude of the backstop, it is possible to prevent the boom from stopping against the operator's intentions.

[0014] In the above configuration, it is preferable to further include 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.

[0015] With this configuration, by notifying the worker that there is a risk of interference between the tip of the backstop and the crane body, the worker can be made aware of the reason why the boom raising and lowering has stopped, and it is possible to reduce the likelihood that the worker will raise or lower the boom with the backstop in the stored position during subsequent work.

[0016] In the above configuration, it is preferable to further include a backstop attitude change unit that is capable of changing the attitude of the backstop between the support attitude and the storage attitude by rotating the backstop around the reference rotation center axis.

[0017] According to this configuration, when the boom hoisting prevention section forcibly stops the boom hoisting operation, the backstop's posture can be changed from the stored posture to the supporting posture, so that the boom hoisting operation can be quickly resumed.

[0018] In the above configuration, the crane body may further include a gantry having a gantry base end supported by the crane body rearward of the boom base end and forward of the backstop receiving portion, and supporting the boom so that the boom can be raised and lowered, the crane body may further have a gantry support part arranged to overlap the backstop when viewed from the front-to-rear direction and supporting the gantry base end, and the interference prevention angle range may be set so as 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.

[0019] With this configuration, even if a gantry is positioned behind the boom and the gantry support part for supporting the gantry is positioned in front of the backstop receiving part in a position 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 advance.

[0020] Furthermore, 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 laid-down 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 abuts against the backstop receiving portion.

[0021] According to 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, thereby reliably preventing interference between the tip of the backstop and the crane body. Effect of the Invention

[0022] According to the present invention, it is possible to prevent interference between a backstop supported on a boom of a crane so as to be able to be raised and lowered and the crane body when the boom is raised and lowered. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a side view of a crane according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of a lower boom and a backstop of the crane according to one embodiment of the present invention when the boom is in a lowered position. [Diagram 3] 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. [Figure 4] 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. [Diagram 5] 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. [Figure 6] 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. [Figure 7] FIG. 2 is a block diagram of a crane according to an embodiment of the present invention. [Figure 8] 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. [Figure 9] 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. [Figure 10] FIG. 2 is a side view showing a state in which a boom is raised in the crane according to one embodiment of the present invention. [Figure 11] 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. [Figure 12]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. [Figure 13] 5 is a flowchart of a boom raising operation control in the crane according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a side view of a crane 10 (work machine) according to one embodiment of the present invention. In the following drawings, directions such as "up", "down", "front" and "rear" 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.

[0025] 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 hoisting rope 22, a boom hoisting winch 30, a main hoisting winch 34, an auxiliary hoisting winch 35, a counterweight 40, and a backstop 45.

[0026] The upper rotating body 12 constitutes the crane body of the crane 10, and is supported by a lower running body 14 so as to be rotatable about a rotation center axis extending in the vertical direction. The lower running body 14 is capable of running on a running surface such as the ground G.

[0027] 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 central 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 the 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 abut against the upper rotating body 12, respectively, when the boom 16 is in an upright position (working position) in which it is further raised from the state shown in FIG. 1. 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.

[0028] The lower spreader 18 is connected to the tip of the gantry 21, and has a lower sheave block (not shown). In the lower sheave block, a plurality of sheaves are arranged in the width direction (left and right direction).

[0029] 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 guy lines 20. The upper spreader 19 has an upper sheave block (not shown). The upper sheave block has a plurality of 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 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.

[0030] 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 substantial triangle with the upper rotating body 12. The rear portion of the gantry 21 is also called a tension member, and extends substantially vertically upward from the rear end of the upper rotating body 12. The front portion of the gantry 21 is also called a compression member, and connects the upper end of the tension member to the front portion of the upper rotating body 12 along an oblique direction. The tension member and the 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.

[0031] The boom hoist rope 22 is pulled out from the boom hoist winch 30 and hung around a sheave (not shown) arranged at the tip of the tension member, and then routed multiple times between the lower sheave block of the lower spreader 18 and the upper sheave block of the upper spreader 19. The tip of the boom hoist rope 22 after being routed around the lower sheave block and the upper sheave block is fixed to the tip (upper end) of the gantry 21.

[0032] 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 in and letting out the boom hoist rope 22, and raises or lowers the boom 16 while rotating the boom 16 relatively to the gantry 21.

[0033] The main winch 34 hoists and lowers a load using a main hoisting rope 51 (FIG. 1). For this main hoisting, a main hoisting guide sheave (not shown) is rotatably provided at the boom tip 16Q of the boom 16, and a main hoisting sheave block is provided adjacent to the main hoisting guide sheave, in which multiple main hoisting point sheaves are arranged in the width direction. A main hook 53 for a load is connected to the main hoisting rope 51 suspended from the main hoisting sheave block. The main hoisting rope 51 drawn out from the main hoisting winch 34 is hung in order on the main hoisting guide sheaves, and is hung between the sheave of the main hoisting sheave block and the sheave of the sheave block provided on the main hook 53. Therefore, when the main hoisting winch 34 winds and unwinds the main hoisting rope 51, the main hook 53 is hoisted and lowered.

[0034] In the same manner, the auxiliary winch 35 hoists and lowers the load using the auxiliary hoisting rope 52. For this auxiliary hoisting, a structure (not shown) similar to that for the main hoisting is provided. When the auxiliary hoisting winch 35 winds or unwinds the auxiliary hoisting rope 52, the auxiliary hook 54 for the load connected to the end of the auxiliary hoisting rope 52 is wound up or lowered.

[0035] In addition, a counterweight 40 for adjusting the balance of the crane 10 is mounted on the rear of the upper rotating body 12.

[0036] 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 the lowered position. Figure 4 is a side view of the crane 10 according to this embodiment when the backstop 45 is in the 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 when the backstop 45 is in the supporting position by the backstop lifting device 60 and the boom 16 is in the upright position.

[0037] Referring to Figures 2 to 5, when the boom 16 (lower boom 16A) is viewed in a state in which it is laid down 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.

[0038] 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 pipe 161 and the second main pipe 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 pipe 161 and the second main pipe 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 plurality of lattice pipes 165 connect the first main pipe 161 and the second main pipe 162, connect a pair of left and right first main pipes 161 to each other, and connect a pair of left and right second main pipes 162 to each other at a plurality of locations.

[0039] Furthermore, the lower boom 16A 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 a backstop fulcrum portion 452S of the backstop 45 described below.

[0040] As described above, the crane 10 is equipped with a pair of left and right backstops 45. The crane 10 further is equipped with a pair of left and right backstop lifting devices 60 (backstop attitude changing devices) that can be attached so as to be interposed between the backstop 45 and the boom 16. Each backstop 45 is disposed on a pair of left and right first main pipes 161. Since 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, hereinafter, the backstop 45 and backstop lifting device 60 on the right side (the front side of the paper in FIG. 2) will be described.

[0041] The backstop 45 has a backstop lower part 451, a backstop upper part 452, and a backstop spring 453. The backstop lower part 451 and the backstop upper part 452 have a cylindrical structure, and the backstop lower part 451 is inserted into the cylindrical interior of the backstop upper part 452 so as to be expandable and contractible. The backstop spring 453 is mounted in a compressible manner between flanges F (FIG. 2) provided on the backstop lower part 451 and the backstop upper part 452, respectively.

[0042] 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 part) 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) by the bracket 161S arranged in a part (a part closer to the boom tip part 16Q) of the lower boom 16A than the boom foot 16S.

[0043] 5, the upper rotating body 12 includes a rotating frame 120, which has a pair of left and right boom attachment 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 only the backstop receiving part 121 on the right side (the front side of the page) is shown in FIG. 5. The boom base end part 16P supported by the boom attachment part 12S is arranged in front of the backstop receiving part 121.

[0044] The backstop lifting device 60 (FIGS. 2 and 4) is capable of changing the position of the backstop 45 between a supporting position (FIG. 4) and a stored position (FIG. 2) by rotating the backstop 45 about a backstop fulcrum part 452S (reference rotation center axis) as a fulcrum when the boom 16 is in a lowered state relative to the upper rotating body 12. The supporting position is a position in which the backstop 45 extends obliquely upward from the boom 16 (lower boom 16A) in the lowered state so that the backstop 45 can restrict the boom 16 from lowering backward by the backstop abutment part 451S of the backstop 45 abutting against the backstop receiving part 121 of the upper rotating body 12 as the boom 16 stands up from the lowered state (see FIG. 4). On the other hand, the stored posture is a posture in which the backstop abutment portion 451S of the backstop 45 is disposed at a position closer to the lower boom 16A (boom 16) than in the supporting posture. Therefore, as shown in Figs. 2 and 4, the backstop lifting device 60 is disposed in the space between the backstop 45 and the first main pipe 161 of the lower boom 16A.

[0045] 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.

[0046] The first arm 61 and the second arm 62 are connected to be bendable and extendable, 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.

[0047] The lifting cylinder 66 is disposed on the upper part of the second arm 62 as shown in FIG. 4. The lifting cylinder 66 is composed of an extendable hydraulic cylinder. When the lifting cylinder 66 extends, the tip of the lifting cylinder 66 pushes up the first arm 61 to stand up against the second arm 62. As a result, the backstop 45 is changed to the supporting position as shown in FIG. 4. On the other hand, when the lifting 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 stored position as shown in FIG. 2.

[0048] 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 maintain 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.

[0049] Fig. 6 is a schematic diagram showing a hydraulic circuit of the backstop lifting device 60 in the crane 10 according to this embodiment. As shown in Fig. 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.

[0050] 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.

[0051] 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 when an operator turns on a switch 801 connected to the control unit 80, and the directional control valve 72 is switched to the contraction position when an operator turns 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 hydraulic oil discharged from the hydraulic pump 71 to the rod chamber 66B and guides hydraulic oil discharged from the head chamber 66A to 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 hydraulic oil discharged from the hydraulic pump 71 from being supplied to the head chamber 66A and the rod chamber 66B, and prevents 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 from some of the piping of the hydraulic circuit, but the cylinder rod 662 can maintain a state in which it is most extended relative to the cylinder body 661, in other words, a state in which the first arm 61 and the second arm 62 form the first angle and the stopper 63 can be attached and detached, for at least a predetermined time. 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 directly discharged into the tank.

[0052] Fig. 7 is a block diagram of the crane 10 according to this embodiment. The block diagram shown in Fig. 7 shows a part of the configuration for controlling the operation of the crane 10.

[0053] 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 a notification unit 95.

[0054] The boom hoist drive unit 31 is capable of receiving a hoist command signal and raising or lowering the boom 16 relative to the upper rotating body 12 in response to the hoist command signal. The boom hoist drive unit 31 includes the boom hoist winch 30 and boom hoist rope 22 described above, as well as a hydraulic circuit including a hydraulic pump and a control valve (not shown) for driving and rotating the boom hoist winch 30. The hoist command signal to the boom hoist drive unit 31 is input from a drive control unit 810 of the control unit 80, which will be described later.

[0055] The control unit 80 controls various operations of the crane 10, and Figure 7 particularly shows controls related to the raising and lowering operation of the boom 16, the lifting and lowering operation of the backstop 45, and the prevention of interference between the backstop 45 and the upper rotating body 12 during the raising and lowering operation of the boom 16.

[0056] The boom operation unit 91 is disposed in the cab of the crane 10, and includes an operation lever and the like that is operated by an operator. The boom operation unit 91 receives operations for raising and lowering the boom 16.

[0057] The lifting / lowering operation unit 92 is disposed in the cab of the crane 10 and is operated by an operator. In this embodiment, the lifting / lowering operation unit 92 is composed of switches 801 and 802 shown in Fig. 6. The lifting / lowering operation unit 92 receives an operation for raising and lowering the backstop 45, that is, for changing the position of the backstop 45 between the above-mentioned supporting position and the stored position.

[0058] 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 a 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.

[0059] The display unit 94 is disposed in the cab of the crane 10 and displays various operational information of the crane 10. Similarly, the alarm unit 95 is disposed in or outside the cab of the crane 10 and generates alarm sounds to notify the operator of various conditions in the crane 10.

[0060] Also, Fig. 8 is an enlarged side view of the backstop 45 of the crane 10 according to this embodiment in a stored position. Fig. 9 is an enlarged side view of the backstop 45 of the crane 10 in a supporting 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 left and right pairs have the same structure, the structure on the right side will be described below.

[0061] The arm support part 621 is provided on the first main pipe 161 of the boom 16, and rotatably supports the base end part of the second arm 62 described above. The limit switch 622 is fixed to the arm support part 621, and is capable of detecting that the backstop 45 is in the support posture. The limit switch 622 has a switch body (not shown) and a pressed part that can appear and disappear from the switch body. In addition, the striker 623 is fixed to the base end part of the second arm 62. As shown in FIG. 8, when the backstop 45 is in the stored posture by the backstop lifting device 60, the striker 623 is disposed away from the pressed part of the limit switch 622, and therefore the limit switch 622 inputs a LOW signal to the control part 80. 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 when a HIGH signal is not input from the limit switch 622.

[0062] 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, a non-illustrated angle meter 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. In addition, in a mode in which the posture detection unit detects only the stored posture of the backstop 45, the backstop 45 may be determined to be in the supporting posture when the posture detection unit does not detect the stored posture of the backstop 45. Note that it is preferable that the posture detection unit is capable of detecting both the supporting posture and the stored posture of the backstop 45. In this case, the posture detection unit is capable of detecting that the backstop 45 is held in an intermediate posture between the supporting posture and the stored posture against the intention of the operator, which prevents the backstop 45 from interfering with surrounding members and enhances safety.

[0063] The control unit 80 described above is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) used as a work area for the CPU, etc. Also connected to the control unit 80 are the boom hoisting drive unit 31, the lift cylinder 66, the boom operation unit 91, the lift operation unit 92, the boom hoist angle detection unit 93, the limit switch 622, the display unit 94, and the notification unit 95. The control unit 80 functions as including 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.

[0064] The drive control unit 810 executes the hoisting operation of the boom 16 and the lifting and lowering operation of the backstop 45 by inputting various command signals to the boom hoisting drive unit 31 and the lifting cylinder 66. The drive control unit 810 inputs the lifting command signal to the boom hoisting drive unit 31 so as to raise and lower the boom 16 in the direction of operation (raising direction, lowering direction) input to the boom operation unit 91 at a drive speed according to the amount of operation. 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 stored position to the supporting position and an instruction to lower the backstop 45 from the supporting position to the stored position, thereby expanding and contracting the lifting cylinder 66 and lifting and lowering the backstop 45.

[0065] 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.

[0066] The determination unit 830 executes various determination processes in the hoisting permission operation of the boom 16 executed by the hoisting permission unit 820.

[0067] The storage unit 840 stores in advance various thresholds, parameters, and the like that are referred to by the drive control unit 810, the undulation permission unit 820, and the determination unit 830.

[0068] Fig. 10 is a side view showing how the boom 16 is raised in the crane 10 according to this embodiment. Fig. 11 is a plan view showing how the boom 16 is raised in the crane 10. Fig. 12 is an enlarged side view showing how the tip of the backstop 45 interferes with the upper rotating body 12, as viewed along the arrows XII-XII in Fig. 11. Note that Figs. 10 and 11 show only the lower boom 16A of the boom 16, and the illustration of other portions is omitted.

[0069] The revolving frame 120 of the upper revolving body 12 has a pair of left and right gantry support parts 210 (Figs. 10 to 12). The gantry support parts 210 are disposed rearward of the boom base end part 16P of the boom 16 and forward of the backstop receiving part 121 (Fig. 5). The gantry support parts 210 rotatably support base ends (gantry base ends) of a pair of left and right tension members of the gantry 21. In the enlarged side view of Fig. 12, the rotation axis 21S of the tension members is shown. As shown in Fig. 11, the pair of gantry support parts 210 are disposed so as to overlap the pair of backstops 45, respectively, when viewed from the front-rear direction.

[0070] With reference to FIG. 10, when the crane 10 is assembled and disassembled, the boom 16 can be lowered with respect 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 such that the center line 16L of the boom 16 extends forward and downward from the boom foot 16S (the 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.

[0071] When the boom 16 or the lower boom 16A is raised from a state in which it is lowered relative to the upper revolving body 12 (the lowered state of the boom) as described above, the backstop 45 is set in a supporting position beforehand. On the other hand, if the boom 16 (the 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 cannot 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 described above, the backstop 45 is extended to its free length by the biasing force of the backstop spring 453 in the unloaded state, and therefore a complex structure is required to shorten the length of the backstop 45 in the stored position in order to prevent the above-mentioned interference.

[0072] In order to solve the above problems, in this embodiment, the control unit 80 has a function of restricting 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, a case where 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 will be described as an example. In this case, if the boom hoist 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 hoist angle θ when the tip of the lower boom 16A is in contact with the ground G is, for example, -10 degrees.

[0073] When this control is started, the determination unit 830 of the control unit 80 determines whether or not a hoisting operation (here, a raising operation) of the boom 16 has been input through the boom operation unit 91 (step S1 in FIG. 13). If a raising operation of the boom 16 has not been input, the determination of step S1 is repeated until a raising operation is input. On the other hand, if a raising operation of the boom 16 has been input in step S1, the boom hoist angle detection unit 93 measures the boom hoist angle θ of the boom 16 (lower boom 16A) (step S2). Note that the boom hoist angle detection unit 93 may constantly acquire the boom hoist angle θ, and the control unit 80 may acquire the detection result in step S2.

[0074] Next, the determination unit 830 determines whether the boom hoisting angle θ acquired in step S2 is included in 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 obliquely upward relative to the upper rotating body 12 and the boom hoisting angle θ is included in 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 manner. 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 in FIG. 10 and the center line 16L of the boom 16 overlap.

[0075] 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 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).

[0076] On the other hand, if the current boom hoist angle θ is not within the working angle range in step S3 (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 posture (step S4). If the backstop 45 is not in the supporting posture (NO in step S4), the determination unit 830 determines whether the current boom hoist angle θ is within the interference prevention angle range (step S5). Note that even if the backstop 45 is in the supporting posture (YES in step S4), there is no risk of interference between the backstop abutment portion 451S and the gantry support portion 210, so the hoist 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).

[0077] The interference prevention angle range is an angle range for the boom hoisting angle θ that is set in advance to guard against (prevent) interference between the backstop abutment part 451S and the gantry support part 210 (a part of the upper rotating body 12 other than the backstop receiving part 121) when the backstop 45 is in the stored posture, 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 part 451S and the gantry support part 210. In this embodiment, the interference prevention angle range is set to a range of the boom hoisting angle θ of -5 degrees or more and +5 degrees or less. That is, the lower limit value 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 value of the interference prevention angle range (upper limit angle, +5 degrees) is set to an angle larger than the lower limit value and smaller than the working angle range described above.

[0078] Therefore, in step S5, if the current boom hoisting angle θ is not included in 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).

[0079] On the other hand, if, in step S5, 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). For this reason, 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.

[0080] Furthermore, in this embodiment, when the raising operation of the lower boom 16A is automatically stopped in step S6, the hoisting permission unit 820 inputs and displays 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. Similarly, the hoisting permission unit 820 inputs the information to the notification unit 95, which notifies the operator of the possibility of interference by a buzzer sound or the like.

[0081] The worker recognizes that the lower boom 16A has been raised with the backstop 45 in the stored position based on the automatic stop of the lower boom 16A and the information notified by the display unit 94 and the notification unit 95. Therefore, the worker interrupts the operation of raising the lower boom 16A through the boom operation unit 91, and operates the lifting operation unit 92 to change the position of the backstop 45 from the stored position to the supporting position.

[0082] When the backstop 45 is in the supporting posture as described above, the backstop abutment portion 451S is disposed above and spaced from the gantry support portion 210, so there is no risk of interference between them. 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, so that the raising operation can be continued (step S7).

[0083] As described above, in this embodiment, the crane 10 has a control unit 80 including a hoist permission unit 820. When the boom hoist 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 for preventing interference between the backstop abutment portion 451S and the gantry support portion 210, with the backstop 45 in the stored posture based on the detection result of the limit switch 622, the hoist permission unit 820 prevents the boom hoist drive unit 31 from performing the hoisting operation of the boom 16, regardless of the input of a hoist command signal to the boom hoist drive unit 31. On the other hand, the hoist permission unit 820 allows the boom hoist drive unit 31 to perform the hoisting operation of the boom 16 with the backstop 45 in the supporting posture based on the detection result of the limit switch 622, regardless of the magnitude of the boom hoist angle θ.

[0084] With this configuration, even if the boom 16 is raised or lowered with the backstop 45 in the stored position, if the boom hoisting angle θ falls within the interference prevention angle range, the hoisting permission section 820 can forcibly prevent the hoisting movement of the boom 16, thereby preventing interference between the backstop abutment section 451S and parts of the upper rotating body 12 other than the backstop receiving section 121, such as the gantry support section 210.

[0085] The above-mentioned 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, the tip of which is in contact with the platform T, is slightly raised, and the lower running body 14 is caused to travel, thereby moving the crane 10 from the 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 is used to prevent the raising operation, thereby preventing such interference from occurring.

[0086] Furthermore, 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.

[0087] Furthermore, in the above description, the lower boom 16A is raised from the ground G or the loading platform T. However, even when 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 hoist permission portion 820 automatically stops the lowering operation of the boom 16, thereby preventing 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 supporting position.

[0088] 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.

[0089] 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 hoist angle reaches the lower limit angle of the interference prevention angle range, the hoist 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 (gantry support unit 210) of the upper rotating body 12. In particular, even if an operator raises the boom 16 without first changing the position of the backstop 45 to the supporting position during the assembly work of the crane 10, the above-mentioned interference can be reliably prevented.

[0090] Furthermore, in this embodiment, when the boom hoisting angle θ is within the work 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.

[0091] 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 intentions during normal operation of the crane 10.

[0092] In this embodiment, the crane 10 is equipped with a display unit 94 and an alarm unit 95 (both of which are alarm devices). The alarm device issues warning information to the operator when the boom hoisting angle θ falls within the interference prevention angle range with the backstop 45 in the stored posture based on the detection result of the limit switch 622.

[0093] According to 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, it is possible to make the operator recognize the reason why the hoisting of the boom 16 has stopped, and it is possible to reduce the operator from hoisting the boom 16 with the backstop 45 in the stored position during subsequent work. The above notification may be made immediately before the automatic stop by the hoisting permission portion 820.

[0094] 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.

[0095] According to this configuration, when the hoisting permission section 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 supporting position, so that the hoisting operation of the boom 16 can be quickly resumed.

[0096] In this embodiment, the crane 10 includes a gantry 21, and the revolving frame 120 of the upper revolving 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.

[0097] With this configuration, even if the gantry 21 is positioned behind the boom 16 and the gantry support part 210 for supporting the gantry 21 is positioned in front of the backstop receiving part 121 in a position 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.

[0098] Furthermore, in this embodiment, the relative height of the backstop 45 in the supporting position with respect to the boom base end 16P is set so that when the backstop 45 is in the supporting position and the boom 16 (lower boom 16A) is raised from its laid-down 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.

[0099] With this configuration, when the backstop 45 is in the supporting position, the backstop abutment portion 451S can pass above the front part of the upper rotating body 12, thereby reliably preventing interference between the backstop abutment portion 451S and the upper rotating body 12.

[0100] 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 present invention allows for the following modified embodiments.

[0101] (1) In the above embodiment, the gantry support part 210 is used as a part with which the backstop abutment part 451S may interfere, but the present invention is not limited to this. The part with which the backstop abutment part 451S may interfere may be a part other than the backstop receiving part 121, such as the front end part of the upper rotating body 12.

[0102] (2) In the above embodiment, the crane 10 is described as being equipped with 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 stored 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, and 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.

[0103] (3) In the above embodiment, the crane 10 shown in FIG. 1 is used for explanation, but the present invention is not limited thereto and can be applied to cranes having other structures. That is, the crane to which the present invention is applied may be one equipped with a lattice mast or a box mast instead of the gantry 21. Also, it may be one equipped with a jib or a strut attached to the tip of the boom. In the above embodiment, the backstop of the boom is used for explanation, but the present invention can be applied to backstops equipped on the mast (lattice mast), struts (rear strut, front strut), and jib. [Explanation of symbols]

[0104] 10. Crane 12 Upper rotating body (crane body) 120 Swivel Frame 121 Backstop receiving part 16. Boom 160 Lower Frame 161 First Main Pipe 16A Lower Boom 16P Boom base end 16Q Boom tip 16S Boom Foot 21 Gantry 210 Gantry support 21S Gantry support part 31 Boom hoisting drive unit 45 Backstop 451 Backstop Lower 451S Backstop contact part (backstop tip) 452 Backstop Top 452S Backstop fulcrum (backstop base end) 453 Backstop Spring 60 Backstop lifting device 61 First Arm 62 Second Arm 621 Arm support 622 Limit switch (posture detection part) 623 Striker 63 Stopper 66 Lifting cylinder 80 Control section 810 Drive control unit 820 Hilling permission section (hilling prevention section) 830 Judgment section 840 Storage section 91 Boom control unit 92 Lifting operation unit 93 Boom hoisting angle detector 94 Display section 95 Notification Department G ground T loading platform

Claims

1. A crane body having an upwardly facing backstop receiving portion; A boom including a boom base end portion 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 portion opposite to the boom base end portion; a boom hoisting drive unit that receives a hoisting command signal and is capable of raising and lowering the boom relative to the crane body in response to the hoisting 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.

2. 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.

3. A crane body having a backstop receiving portion facing upward, A boom including a boom base end portion 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 portion opposite to the boom base end portion; a boom hoisting drive unit that receives a hoisting command signal and is capable of raising and lowering the boom relative to the crane body in response to the hoisting 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.

4. The crane according to any one of claims 1 to 3, further comprising a backstop attitude changing 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.

5. A crane body having a backstop receiving portion facing upward, A boom including a boom base end portion 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 portion opposite to the boom base end portion; a boom hoisting drive unit that receives a hoisting command signal and is capable of raising and lowering the boom relative to the crane body in response to the hoisting 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. 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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