Lifting device for suspended load

Abstract

To provide a lifting device for a suspended load, which has a short vertical length, can easily secure a lifting height, and is small in size and light in weight.SOLUTION: A lifting device A for a suspended load, according to the present invention, comprises: a suspending member 1 provided with a locking portion for locking a crane hook; first and second hydraulic cylinders 2, 3 rotatably coupled to the suspending member 1 independently of each other, partitioned into upper and lower chambers by pistons 22, 32, and having connecting portions 24, 34 at respective lower ends of piston rods 23, 33 projectingly provided on respective lower surfaces of the pistons 22, 32; a third hydraulic cylinder in which a spring member 43 for pressing a piston 42 is disposed in one chamber 41a separated by the piston 42; and a conduit 5 by which inside of each of lower chambers 21b, 31b of the first and second hydraulic cylinders 2, 3 and inside of the other chamber 41b of the third hydraulic cylinder 4 connect and communicate with each other by means of an electromagnetic valve so as to be freely opened and closed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a load hoisting device that has the function of easily correcting the attitude of a load such as a container (hereinafter referred to as a "load") to a horizontal state when the load becomes tilted when the load is hoisted, and automatically returning the load to its original state when the load is removed. [Background technology]

[0002] Conventionally, to lift a load with a crane and lower it to a specified location, multiple cables such as wires are slung at the top end of the crane's lifting hook, and the load is supported by these cables, but if the center of gravity of the load is offset in either direction from the center of the load's length or width, the load is lifted in an inclined state, causing the load's posture to become unstable. For this reason, as disclosed in Patent Document 1, for example, a load lifting device equipped with a load posture correction mechanism has been proposed.

[0003] The load posture correction mechanism is configured such that a hydraulic cylinder such as a hydraulic cylinder is connected to the rope that supports the load, and when the load hoisted by the crane tilts, the piston rod of the hydraulic cylinder attached to the rope connected to the upper inclined end of the load is displaced downward, thereby correcting the posture of the load to a horizontal state.

[0004] Furthermore, in the load lifting device, a piston return tension spring is attached to the piston rod of the hydraulic cylinder in the posture correction mechanism, and when the load is lowered, this return spring moves the piston rod upward to return it to its original position, ready for lifting the next load. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-111609 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned load lifting device uses a double rod cylinder with rods on the top and bottom surfaces of the piston of the hydraulic cylinder, which makes the hydraulic cylinder long in vertical length, making it difficult to use in places where the lifting height when lifting a load is insufficient. Also, the return tension spring is long, making the load lifting device large and heavy.

[0007] The present invention has been made in consideration of the above problems, and its object is to provide a small, lightweight load lifting device that has a short vertical length, can easily ensure a lifting height, and is compact and lightweight. [Means for solving the problem]

[0008] The load hoisting device of the present invention comprises: a hoisting member having an engaging portion on an upper surface for detachably engaging a crane hook; a first hydraulic cylinder and a second hydraulic cylinder, the upper ends of which are connected to one end side and the other end side of the suspension member so as to be rotatable independently of each other, the first hydraulic cylinder and the second hydraulic cylinder are partitioned into upper and lower chambers by a piston, and the first hydraulic cylinder and the second hydraulic cylinder have a connecting portion for detachably connecting a rope connected to a suspended load to the lower end of a piston rod protruding from a lower surface of the piston; a third hydraulic cylinder which is integral with the suspension member and has two chambers defined by a piston, and a spring member which presses the piston is disposed in one of the chambers; The hydraulic cylinder is characterized in that it has a pipeline that connects and communicates the lower chambers of the first and second hydraulic cylinders and the other chamber of the third hydraulic cylinder in a manner that can be opened and closed by an electromagnetic valve, and is filled with pressure liquid. Effect of the Invention

[0009] In the load lifting device of the present invention, the first and second hydraulic cylinders having a connection part for connecting the rope connected to the load and the third hydraulic cylinder are provided independently on the lifting member, and the pressure liquid discharged from the lower chambers of the first and second hydraulic cylinders (the other chamber of the third hydraulic cylinder) as the pistons of the first and second hydraulic cylinders move downward (upward) is accommodated in the other chamber of the separate third hydraulic cylinder (the lower chamber of the first and second hydraulic cylinders). Therefore, it is not necessary to arrange the first and second hydraulic cylinders and the third hydraulic cylinder in parallel in the vertical direction, and it is possible to arrange the first and second hydraulic cylinders and the third hydraulic cylinder in the left-right direction, and it is possible to increase the length of the lower chambers of the first and second hydraulic cylinders while preventing the vertical dimension of the load lifting device from becoming long, thereby increasing the lifting distance of the load and reducing the vertical size of the load lifting device, and it is possible to lift the load with a sufficient lifting height even in a narrow working space.

[0010] In the above-mentioned load lifting device, when the above-mentioned solenoid valves are provided in each of the pipelines connecting and communicating the first hydraulic cylinder and the third hydraulic cylinder, and the pipelines connecting and communicating the second hydraulic cylinder and the third hydraulic cylinder, the downward movement of the pistons in the first hydraulic cylinder and the second hydraulic cylinder can be adjusted independently by operating these solenoid valves, and the inclined state of the load can be quickly and accurately corrected to a desired state, such as a horizontal state.

[0011] In the above-mentioned load lifting device, if the pipeline is provided with a bypass pipeline that bypasses the solenoid valve and a check valve is provided in the bypass pipeline to prevent the flow of pressurized liquid from the first and second hydraulic cylinders to the third hydraulic cylinder, then when the load suspended via a rope from the connection between the first and second hydraulic cylinders is detached and the load of the load is removed from the first and second hydraulic cylinders, the spring member of the third hydraulic cylinder returns the pressurized liquid contained in the other chamber of the third hydraulic cylinder to the first and second hydraulic cylinders via the bypass pipeline, and the connection between the first and second hydraulic cylinders is quickly restored to its original state (initial state) in preparation for the next load lifting operation.

[0012] In the above-mentioned load lifting device, one end of the pipeline is connected and communicated with the other chamber of the third hydraulic cylinder, while the other end is branched at a branching section, with one branched end connected and communicated with the lower chamber of the first hydraulic cylinder and the other branched end connected and communicated with the lower chamber of the second hydraulic cylinder. When the solenoid valve is interposed at the branching section, the third hydraulic cylinder connected and communicated with the lower chambers of the first and second hydraulic cylinders can be shared, thereby making it possible to reduce the size and weight of the load lifting device.

[0013] In the above-mentioned load lifting device, when the solenoid valve has an open position that allows communication between the lower chamber of only one of the first and second hydraulic cylinders and the other chamber of the third hydraulic cylinder, and a closed position that blocks communication between the lower chambers of both the first and second hydraulic cylinders and the other chamber of the third hydraulic cylinder, by setting the solenoid valve to the open position, the lower chamber of either the first hydraulic cylinder or the second hydraulic cylinder is communicated with the other chamber of the third hydraulic cylinder, and the piston rod of either hydraulic cylinder is moved downward to reliably correct the inclination of the load to a desired state such as a horizontal state, while by setting the solenoid valve to the closed position, the height position of the connection part of the lower ends of the piston rods of the first and second hydraulic cylinders is maintained, and the desired state of the load is reliably maintained. In this way, the downward movement of the connection part of the first hydraulic cylinder or the second hydraulic cylinder can be controlled by a single solenoid valve, and the load lifting device can be made smaller and lighter. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a front view showing the load lifting device of the present invention. [Diagram 2] FIG. 2 is a side view showing a load lifting device. [Diagram 3] FIG. 2 is a diagram showing the configuration of the pipeline of a lifting device for a suspended load. [Figure 4] FIG. 2 is a front view showing the load hoisting device in use (before the load posture is corrected). [Diagram 5] FIG. 2 is a front view showing the load hoisting device in use (after the load posture has been corrected). [Figure 6] FIG. 11 is a configuration diagram showing another example of a pipeline of a load lifting device. [Figure 7] FIG. 11 is a configuration diagram showing another example of a pipeline of a load lifting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An example of a load hoisting device of the present invention will be described with reference to the drawings. As shown in Figures 1 and 2, the load hoisting device A includes a hoisting member 1 having a locking portion B formed in the center of the upper surface side for detachably locking a crane hook (not shown), a first hydraulic cylinder 2 and a second hydraulic cylinder 3 integrally provided on the lower surface of the hoisting member 1 so as to be rotatable in the left-right direction, and a third hydraulic cylinder 4 integrally provided between the first hydraulic cylinder 2 and the second hydraulic cylinder 3 on the lower surface of the hoisting member 1.

[0016] A first hydraulic cylinder 2 and a second hydraulic cylinder 3 are provided at the upper ends of the left and right ends of the lower surface of the suspending member 1, integrally and rotatably with respect to the suspending member 1. The first hydraulic cylinder 2 and the second hydraulic cylinder 3 are provided rotatably in the left and right directions independently of each other with respect to the suspending member 1. The first hydraulic cylinder 2 and the third hydraulic cylinder 3 rotate independently of each other with respect to the suspending member 1 according to the degree of inclination of the load C, and by moving downward a piston 22 (32) of either the first hydraulic cylinder 2 or the third hydraulic cylinder 3 described later, the load C in an inclined state can be quickly corrected to a horizontal state. Moreover, by rotating the first hydraulic cylinder 2 and the second hydraulic cylinder 3 independently of each other, excessive stress is prevented from being applied to the piston rods 23, 33 protruding downward from the cylinder tubes 21 and 31 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 when correcting the inclined state of the load, and damage such as bending of the piston rods 23, 33 is prevented.

[0017] The first hydraulic cylinder 2 and the second hydraulic cylinder 3 (collectively sometimes simply referred to as "hydraulic cylinders") have the same structure. However, the first hydraulic cylinder 2 and the second hydraulic cylinder 3 may have structures different from each other.

[0018] The first hydraulic cylinder 2 and the second hydraulic cylinder 3 each include a cylinder tube 21, 31 having a fixed length, a piston 22, 32 disposed within the cylinder tube 21, 31 so as to be able to slide vertically, a piston rod 23, 33 of a fixed length provided at the center of the lower surface of the piston 22, 32 to protrude downward and to protrude liquid-tightly and slidably from the lower end surface of the cylinder tube 21, 31, and a connecting portion 24, 34 such as a hook provided integrally with the lower end of the piston rod 23, 33 protruding downward from the cylinder tube 21, 31.

[0019] The inside of the cylinder tubes 21, 31 of the hydraulic cylinders is divided into upper and lower chambers 21a, 21b (31a, 31b) by pistons 22, 32. The lower chambers 21b, 31b of the cylinder tubes 21, 31 in the hydraulic cylinders are filled with pressure liquid (pressure oil, pressure water, etc.) E.

[0020] Furthermore, since no piston rods are protruding from the upper surfaces of the pistons 22, 32 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3, and there is no inflow or outflow of pressure liquid E into the upper chambers 21a, 31a, there is no need to provide a structure for circulating pressure liquid E, and the vertical length of the cylinder tubes 21, 31 of the hydraulic cylinders can be shortened, preventing the vertical dimension of the lifting device for the load from becoming long. Therefore, the posture of the load can be easily corrected even in a narrow working space where a sufficient lifting height cannot be secured.

[0021] In addition, the upper chambers 21a, 31a of the cylinder tubes 21, 31 in the hydraulic cylinder are hollow and have air holes (not shown) formed penetrating inward and outward directions of the upper chambers 21a, 31a, so that air can flow in and out of the upper chambers 21a, 31a through the air holes in response to the up and down movement of the pistons 22, 32 of the hydraulic cylinder.

[0022] A third hydraulic cylinder 4 is provided integrally between the first hydraulic cylinder 2 and the second hydraulic cylinder 3 at the center of the underside of the hanging member 1. The third hydraulic cylinder 4 has a cylinder tube 41 having a certain length, and a piston 42 that is disposed within this cylinder tube 41 so as to be able to slide vertically and divides the inside of the cylinder tube 41 into two chambers (one chamber 41a and the other chamber 41b).

[0023] A spring member 43 is disposed in a compressed state in one chamber 41a formed in the cylinder tube 41, and constantly presses the piston 42 toward the other chamber 41b. The other chamber 41b of the cylinder tube 41 in the third hydraulic cylinder 4 is filled with pressure fluid E.

[0024] A piston stop mechanism (not shown) is provided in the cylinder tube 41. The piston stop mechanism restricts the piston 42 from moving beyond a predetermined position toward one chamber 41a in the cylinder tube 41, and prevents the spring member 43 from being fully contracted. This prevents the spring member 43 from being damaged unexpectedly when an excessive load is applied to either the first hydraulic cylinder or the second hydraulic cylinder and the pressure liquid E in the first hydraulic cylinder 2 or the second hydraulic cylinder 3 excessively flows into the other chamber 41b of the third hydraulic cylinder 4 by an operation described later, when a load C suspended by the connecting parts 24, 34 of the hydraulic cylinders via the ropes D, D exceeds the allowable weight or when the center of gravity of the load is significantly biased in either direction.

[0025] 1 shows a case where the upper chamber of the cylinder tube 41 is the one chamber 41a and the spring member 43 is disposed in this one chamber 41a, but the lower chamber of the cylinder tube 41 may be the one chamber 41a. That is, in FIG. 1, the spring member may be disposed in the lower chamber of the cylinder tube 41, while the upper chamber may be filled with pressure liquid.

[0026] 3, the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4 are connected and communicated by a pipe 5 filled with pressure liquid E. The pipe 5, the solenoid valve 5a and the check valve interposed in the pipe 5, and the bypass pipe are accommodated in an accommodation chamber F that is integrally provided on the lower surface of the hanging member 1.

[0027] In detail, one end 51 of the pipe 5 is connected and communicated with the other chamber 41b of the third hydraulic cylinder 4, while the other end of the pipe 5 is branched into two at a branching portion 52, one branched end 53 is connected and communicated with the lower chamber 21b of the first hydraulic cylinder 2, and the other branched end 54 is connected and communicated with the lower chamber 31b of the second hydraulic cylinder 3. The lower chambers 21b, 31b of the hydraulic cylinders and the pipe 5 are completely filled with pressure liquid E.

[0028] A solenoid valve 5a is interposed in the branching portion 52 of the pipe 5. The solenoid valve 5a has an open position that allows communication between the lower chamber 21b (31b) of only one of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4, and a closed position that blocks communication between the lower chambers 21b, 31b of both of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4. The solenoid valve 5a is in the closed position in the initial state, and is configured to prevent the pressure liquid E in the lower chambers 21b, 31b of both the first hydraulic cylinder 2 and the second hydraulic cylinder 3 from flowing into the other chamber 41b of the third hydraulic cylinder 4, and to prevent the connection portions 24, 34 of the first hydraulic cylinder and the second hydraulic cylinder 3 from moving downward.

[0029] A control device (not shown) including a CPU that controls the solenoid valve 5a, and a ROM, RAM, storage device (e.g., HDD, SSD, etc.) and a communication device electrically connected to the CPU is housed in the accommodation chamber F. The control device is configured to communicate with a remote controller operated by an operator via the communication device, receive a signal transmitted from the remote controller, and switch the solenoid valve 5a between a closed position and an open position under the control of the CPU.

[0030] In other words, the solenoid valve 5a interposed in the branching portion 52 of the pipe 5 is configured to either communicate the other chamber 41b of the third hydraulic cylinder 4 with only one of the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 to allow communication therebetween (open position), or not to simultaneously communicate the lower chambers 21b, 31b of both the first hydraulic cylinder 2 and the second hydraulic cylinder 3 with the other chamber 41b of the third hydraulic cylinder 4 (closed position). The solenoid valve 5a is configured so that the pressure liquids in the lower chambers 21b, 31b of both the first hydraulic cylinder 2 and the second hydraulic cylinder 3 do not flow simultaneously into the other chamber 41b of the third hydraulic cylinder 4, causing the connections 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 to move downward simultaneously.

[0031] Since the third cylinder 4, which allows the pressure liquid in the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 to flow in and evacuate when the connecting parts 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 move downward, is provided independently of the first hydraulic cylinder 2 and the second hydraulic cylinder 3, it is possible to adjust the size of the other chamber 41b of the third cylinder 4 and evacuate the required amount of pressure liquid in the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 by adjusting the horizontal cross-sectional area without changing the height of the third cylinder 4, without needing to change the vertical height of the first hydraulic cylinder 2 and the second hydraulic cylinder 3. Therefore, the first hydraulic cylinder 2 and the second hydraulic cylinder 3 only need to have a vertical height slightly higher than the desired downward movement distance of the connecting parts 24, 34, and the vertical height can be suppressed by adjusting the horizontal cross-sectional area of ​​the third hydraulic cylinder 4, so that the vertical height of the load lifting device can be made as small as possible to achieve a compact size.

[0032] Furthermore, by sharing the other chamber 41b of the third hydraulic cylinder 4 as the evacuation location for the pressurized liquid E in the lower chambers 21b, 31b when the connection parts 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 move downward, the size of the other chamber 41b of the third hydraulic cylinder 4 can be reduced, and ultimately the load lifting device A can be made smaller and lighter.

[0033] The pipeline 5 is provided with a first bypass pipeline 6 and a second bypass pipeline 7 which bypass the solenoid valve 5a.

[0034] Specifically, the first bypass pipeline 6 has one end 61 connected and communicating between the solenoid valve 5a in the pipeline 5 and the other chamber 41b of the third hydraulic cylinder 4, and the other end 62 connected and communicating between the solenoid valve 5a in the pipeline 5 and the lower chamber 21b of the first hydraulic cylinder 2.

[0035] Furthermore, a check valve 6a is provided in the first bypass line 6 which always allows communication from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 21b of the first hydraulic cylinder 2, while always blocking communication from the lower chamber 21b of the first hydraulic cylinder 2 to the other chamber 41b of the third hydraulic cylinder 4.

[0036] The second bypass pipe 7 has one end 71 connected and communicating between the solenoid valve 5a in the pipe 5 and the other chamber 41b of the third hydraulic cylinder 4, and the other end 72 connected and communicating between the solenoid valve 5a in the pipe 5 and the lower chamber 31b of the second hydraulic cylinder 3.

[0037] Furthermore, a check valve 7a is provided in the second bypass line 7 which always permits communication from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 31b of the second hydraulic cylinder 3, while always blocking communication from the lower chamber 31b of the second hydraulic cylinder 3 to the other chamber 41b of the third hydraulic cylinder 4.

[0038] Further, in the pipe 5, a first flow rate control valve 5b is interposed between the other end 62 of the first bypass pipe 6 and the lower chamber 21b of the first hydraulic cylinder 2. Similarly, in the pipe 5, a second flow rate control valve 5c is interposed between the other end 72 of the second bypass pipe 7 and the lower chamber 31b of the second hydraulic cylinder 3. By adjusting the degree of opening of the first flow rate control valve 5b and the second flow rate control valve 5c, the inflow speed of the pressure liquid E from the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 to the other chamber 41b of the third hydraulic cylinder 4 can be adjusted, and the downward movement speed of the connection parts 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 can be adjusted.

[0039] The first flow rate control valve 5b always allows flow from the lower chamber 21b of the first hydraulic cylinder 2 to the other chamber 41b of the third hydraulic cylinder 4. The first flow rate control valve 5b may have a built-in check valve that always blocks flow from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 21b of the first hydraulic cylinder 2. Similarly, the second flow rate control valve 5c always allows flow from the lower chamber 31b of the second hydraulic cylinder 3 to the other chamber 41b of the third hydraulic cylinder 4. The first flow rate control valve 5b may have a built-in check valve that always blocks flow from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 31b of the second hydraulic cylinder 3.

[0040] Furthermore, a third bypass pipe 8 that bypasses the first flow rate control valve 5b is provided in the pipe 5. One end 81 of the third bypass pipe 8 is connected and communicated between the first flow rate control valve 5b in the pipe 5 and the other end 62 of the first bypass pipe 6, and the other end 82 is connected and communicated between the first flow rate control valve 5b and the lower chamber 21b of the first hydraulic cylinder 2. A check valve 8a is interposed in the third bypass pipe 8, which always allows communication from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 21b of the first hydraulic cylinder 2, but always blocks communication from the lower chamber 21b of the first hydraulic cylinder 2 to the other chamber 41b of the third hydraulic cylinder 4.

[0041] Further, a fourth bypass pipe 9 that bypasses the second flow control valve 5c is provided in the pipe 5. One end 91 of the fourth bypass pipe 9 is connected and communicated between the second flow control valve 5c in the pipe 5 and the other end 72 of the second bus path pipe 7, and the other end 92 is connected and communicated between the second flow control valve 5c and the lower chamber 31b of the second hydraulic cylinder 3. A check valve 9a is interposed in the fourth bypass pipe 9, which always allows communication from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 31b of the second hydraulic cylinder 3, but always blocks communication from the lower chamber 31b of the second hydraulic cylinder 3 to the other chamber 41b of the third hydraulic cylinder 4.

[0042] Next, we will explain how to use the load hoisting device A. In the initial state, the solenoid valve 5a in the pipeline 5 of the load hoisting device A is in the closed position, and the flow of pressure liquid E between the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4 in the pipeline 5 is blocked.

[0043] On the other hand, the first bypass line 6 and the third bypass line 8 always allow communication from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 21b of the first hydraulic cylinder 2, and the second bypass line 7 and the fourth bypass line 9 always allow communication from the other chamber 41b of the third hydraulic cylinder 4 to the lower chamber 31b of the second hydraulic cylinder 3.

[0044] In the load lifting device A, in the initial state where the load C is not suspended from the connection parts 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3, the force pressing the piston 42 by the spring member 43 of the third hydraulic cylinder 4 toward the other chamber 41b is configured to be greater than the weight of the pistons 22, 32, piston rods 23, 33 and connection parts (hooks) 25, 35 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3. Therefore, due to the pressing force of the spring member 43, the pressurized liquid E in the other chamber 41b of the third hydraulic cylinder 4 bypasses the solenoid valve 5a of the pipe line 5, and flows into the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 through the pipe line portion on the third hydraulic cylinder 4 side of the solenoid valve 5a and the first to fourth bypass pipe lines 6-9, thereby moving the pistons 22, 32 upward and positioning the connection parts 24, 34 at the lower ends of the piston rods 23, 33 at their highest positions (initial positions).

[0045] A single rope D is connected to the connection part 24 of the first hydraulic cylinder 2 of the load lifting device A in the initial state as described above by engaging the upper end bent part, which is bent from the center into an inverted V shape, in a manner that allows it to be freely engaged and detached, and both ends of the rope D engaged to the connection part 24 are respectively attached to the front and rear corner parts at the upper end of the load C.

[0046] Similarly, another cable D is connected to the connection part 34 of the second hydraulic cylinder 3 by engaging its upper bent part, which is bent from the center into an inverted V shape, and both ends of the cable D engaged with the connection part 34 are attached to the front and rear corner parts of the other upper end part of the suspended load C. Furthermore, a hook (not shown) of a crane is hooked and engaged with the engaging part B of the suspension member 1 of the lifting device A for the suspended load.

[0047] Thereafter, the crane is operated to hoist the load C as shown in Fig. 4. Then, a force is applied by the weight of the load C to move the connections 24, 34 of the hydraulic cylinders downward, but since the solenoid valve 5a of the pipeline 5 is in the closed position and the check valves 6a, 7a of the first bypass pipeline 6 and the second bypass pipeline 7 prevent the flow of pressure liquid E from the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 to the other chamber 41b of the third hydraulic cylinder 4, the connections 24, 34 at the lower ends of the piston rods 23, 33 do not move downward, and the load C is hoisted via the ropes D, D.

[0048] When lifting load C as described above, for example, if the center of gravity of load C is offset from the center of the length of load C (left-right direction in Figures 4 and 5) toward one end, load C will be lifted by ropes D, D in an attitude inclined diagonally upward from one end (left end) to the other end (right end) as shown in Figure 4.

[0049] On the other hand, since the first hydraulic cylinder 2 and the second hydraulic cylinder 3 are independently connected to the hoisting member 1 so as to be rotatable about their upper ends, the first hydraulic cylinder 2 and the second hydraulic cylinder 3 can be independently rotated and displaced so as to be located on the extension line of the ropes D, D, and can be inclined. Therefore, in the initial state, the inclination state of the load C is corrected to be as small as possible, and the protruding length (stroke length) of the piston rods 23, 33 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 can be shortened when correcting the load C to a desired state. Therefore, the vertical length of the cylinder tubes 21, 31 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 can be shortened, and the size and weight can be reduced. Furthermore, the load is applied evenly to the pistons 22, 32 and the piston rods 23, 33 in the cylinder tubes 21, 31 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3, and damage caused by partial application of excessive load can be prevented in advance.

[0050] An operator visually checks the inclined posture of the load C, communicates with the control device of the load lifting device A using a remote controller (not shown), and corrects the posture of the load C so that it is in a stable horizontal state as shown in Figure 5.

[0051] That is, when the load C is lifted in a state inclined upward from one end side to the other end side due to the unbalanced load of the load C as described above, the solenoid valve 5a of the pipe 5 is controlled to change the solenoid valve 5a from the closed position to the open position, thereby communicating the lower chamber 31b of the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4 and enabling the flow of pressure liquid E between the two chambers. Meanwhile, the flow of pressure liquid between the lower chamber 21b of the first hydraulic cylinder 2 and the other chamber 41b of the third hydraulic cylinder 4 remains blocked.

[0052] The piston 32 of the second hydraulic cylinder 3 moves downward while pressure-feeding the pressure liquid E in the lower chamber 31b into the other chamber 41b of the third hydraulic cylinder 4 through the pipe 5 due to the load of the suspended load C applied to the connection part 34. At this time, the pressure liquid E is pressure-feed into the other chamber 41b of the third hydraulic cylinder 4 against the elastic force of the spring member 43 of the third hydraulic cylinder 4, and the spring member 43 of the third hydraulic cylinder 4 becomes contracted from the initial state. In addition, a second flow control valve 5c is interposed in the pipe 5 to adjust the flow rate of the pressure liquid E flowing through the pipe 5, so that the piston 32 moves downward at an appropriate speed. On the other hand, the piston 22 of the first hydraulic cylinder 2, which supports the downward inclined end side (one end side) of the suspended load C, is in an inoperative state because the flow of the pressure liquid E between the lower chamber 21b of the first hydraulic cylinder 2 and the other chamber 41b of the third hydraulic cylinder 4 is blocked.

[0053] As described above, when the piston 32 of the second hydraulic cylinder 3 moves downward, the connection part 34 at the lower end of the piston rod 33 integrally formed with the piston 32 also moves downward integrally, and the suspension fulcrum (upper end bent part) of the rope D, which is engaged with this connection part 34 and connected at its lower end to the other end of the load C to suspend the other end of the load C, moves downward around the suspension fulcrum (upper end bent point) of the rope D, which is engaged with the connection part 24 of the first hydraulic cylinder 2 and connected at its lower end to one end of the load C to suspend one end of the load C, as a fulcrum, and the load C is corrected from its inclined posture to a horizontal state. After achieving this state, the solenoid valve 5a is switched to the closed position by remote control to block communication between the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4, and fixes the connection parts 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 so that they do not move up and down.

[0054] When one end of the load C is inclined upward relative to the other end, the solenoid valve 5a of the pipe 5 is controlled to change the solenoid valve 5a from the closed position to the open position, thereby communicating the lower chamber 21b of the first hydraulic cylinder 2 with the other chamber 41b of the third hydraulic cylinder 4 to enable the flow of pressure liquid E between the two chambers, and the piston 22 of the first hydraulic cylinder 2 is moved downward by the load of the load C applied to the connection part 24 while pressure-feeding the pressure liquid E in the lower chamber 21b into the other chamber 41b of the third hydraulic cylinder 4 through the pipe 5. Meanwhile, the piston 32 of the second hydraulic cylinder 3 supporting the downward inclined end side (other end side) of the load C is in an inoperative state since the flow of pressure liquid E between the lower chamber 31b of the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4 is blocked.

[0055] In this way, the posture of the load C is corrected to a horizontal state, and the load C is transported to a specified location by a crane, and then lowered at that location and allowed to touch the ground, etc., whereupon the tension in the rope D is released and the load of the load C acting on the connection parts 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 is released.

[0056] Then, the piston 42 is displaced toward the other chamber 41b by the pressing force of the spring member 43 of the third hydraulic cylinder 4, and the pressurized liquid in the other chamber 41b of the third hydraulic cylinder 4 flows through the pipe portion on the third hydraulic cylinder 4 side rather than the solenoid valve 5a and the first bypass pipe lines 6-9, bypassing the solenoid valve 5a which is in the closed position, and into the lower chambers 21b, 31b of the first hydraulic cylinder 2 and the second hydraulic cylinder 3, moving the pistons 22, 32 upward and returning the connection parts 24, 34 at the lower ends of the piston rods 23, 33 to their initial positions, in preparation for the next lifting operation.

[0057] The above describes a method for correcting the load C from an inclined position to a horizontal position, but it is also possible to use the load hoisting device A to move the connections 24, 34 of the first hydraulic cylinder 2 and the second hydraulic cylinder 3 downward in the same manner as described above to correct the load C from a horizontal position to an inclined position. Thereafter, the load C in an inclined position can be returned to a horizontal position in the same manner as described above. In this way, the load hoisting device A described above can correct the load C from an inclined position to a horizontal position or vice versa, and can also correct the load C from an inclined position having a predetermined inclination angle to an inclined position having a different inclination angle.

[0058] In the load lifting device A described above, one solenoid valve 5a is provided at the branching portion 52 of the pipe 5, and this solenoid valve 5a establishes or blocks communication between the other chamber 41b of the third hydraulic cylinder 4 and the lower chambers 21b, 31b of the hydraulic cylinders. However, as shown in FIG. 6, solenoid valves 5a' (5a") may be provided at positions shifted toward the first hydraulic cylinder 2 (second hydraulic cylinder 3) from the branching portion 52 of the pipe 5, and communication between the other chamber 41b of the third hydraulic cylinder 4 and the lower chamber 21b of the first hydraulic cylinder 2 and communication between the other chamber 41b of the third hydraulic cylinder 4 and the lower chamber 31b of the second hydraulic cylinder 3 may be established or blocked independently of each other.

[0059] In addition, in the above-mentioned load lifting device A, the pipeline 5 between the third hydraulic cylinder 4 and the solenoid valve 5a is shared as a single pipeline, but as shown in FIG. 7, the pipeline 5' connecting and communicating the lower chamber 21b of the first hydraulic cylinder 2 and the other chamber 41b of the third hydraulic cylinder 4, and the pipeline 5'' connecting and communicating the lower chamber 31b of the second hydraulic cylinder 3 and the other chamber 41b of the third hydraulic cylinder 4 may be provided independently of each other, and solenoid valves 5a', 5a'' may be interposed in each pipeline.

[0060] In the above, the case where the first hydraulic cylinder 2 and the second hydraulic cylinder 3 are provided as hydraulic cylinders having a piston rod with a connection portion at the lower end in the load lifting device A has been described, but three or more hydraulic cylinders, for example, four hydraulic cylinders, may be provided and each of these hydraulic cylinders may be connected to the other chamber 41b of the third hydraulic cylinder 4 via a pipe in the same manner as the first hydraulic cylinder 2 and the second hydraulic cylinder 3. In this case, solenoid valves for opening and closing these pipes are provided in the pipes connecting and communicating the lower chambers of each hydraulic cylinder with the other chamber of the third hydraulic cylinder in the same manner as described above. [Explanation of symbols]

[0061] 1 Hanging member 2. First hydraulic cylinder 21 Cylinder tube 21a Upper chamber 21b Lower chamber 22 Piston 23 Piston rod 24 Connection 3. No. 2 hydraulic cylinder 31 Cylinder tube 31a Upper chamber 31b Lower chamber 32 Piston 33 Piston rod 34 Connection 4. No. 3 hydraulic cylinder 41 Cylinder tube 41a One Room 41b The other room 42 Piston 43 Spring parts 5 conduit 5a, 5', 5" solenoid valve 5b First flow control valve 5c Second flow control valve 6 First bypass pipeline 7 Second bypass pipeline 8. Third bypass pipeline 8a Check valve 9. 4th Bypass Pipeline 9a Check valve A device B Locking part C Hanging load D cable E Pressure Fluid F Containment Room

Claims

1. A hanging member having an engaging portion on an upper surface for detachably engaging a crane hook; a first hydraulic cylinder and a second hydraulic cylinder, the upper ends of which are connected to one end side and the other end side of the suspension member so as to be rotatable independently of each other, the first hydraulic cylinder and the second hydraulic cylinder are partitioned into upper and lower chambers by a piston, and the first hydraulic cylinder and the second hydraulic cylinder have a connecting portion for detachably connecting a rope connected to a suspended load to a lower end of a piston rod protruding from a lower surface of the piston; a third hydraulic cylinder which is integrally provided with the suspension member and has two chambers defined by a piston, and a spring member which presses the piston is disposed in one of the chambers; a hydraulic cylinder that is connected to the lower chambers of the first and second hydraulic cylinders and the other chamber of the third hydraulic cylinder by an electromagnetic valve so as to be freely opened and closed, and a pipeline filled with pressurized liquid.

2. 2. The load lifting device according to claim 1, wherein the solenoid valve is provided in each of a pipeline connecting and communicating the first hydraulic cylinder and the third hydraulic cylinder, and a pipeline connecting and communicating the second hydraulic cylinder and the third hydraulic cylinder.

3. 2. The load lifting device according to claim 1, wherein the pipeline is provided with a bypass pipeline that bypasses the solenoid valve, and a check valve is provided in the bypass pipeline to prevent the flow of pressure liquid from the first hydraulic cylinder and the second hydraulic cylinder to the third hydraulic cylinder.

4. 2. The load lifting device according to claim 1, wherein one end of the pipeline is connected and communicated with the other chamber of the third hydraulic cylinder, while the other end is branched at a branching portion, one branched end is connected and communicated with the lower chamber of the first hydraulic cylinder, and the other branched end is connected and communicated with the lower chamber of the second hydraulic cylinder, and the solenoid valve is interposed in the branching portion.

5. 5. The load lifting device according to claim 4, wherein the solenoid valve has an open position which allows communication between a lower chamber of only one of the first and second hydraulic cylinders and the other chamber of the third hydraulic cylinder, and a closed position which blocks communication between the lower chambers of both the first and second hydraulic cylinders and the other chamber of the third hydraulic cylinder.

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