crane

Abstract

The present invention aims to reduce the positional deviation between the boom tip and the hook after the start of the hoisting operation. The present invention provides a crane (1) having a boom (4) and hoisting a load (L) from the tip of the boom (4) via a hook (34), which performs positional adjustment control that brings the position of the hook (34) and the position of the tip of the boom (4) close to each other when viewed from the vertical direction during the period from the start of the hoisting operation until the load (L) leaves the ground surface. In the positional adjustment control, either one of the raising and lowering of the heave operation of the boom (4) can be performed in accordance with the relative movement direction of the hook (34) with respect to the crane body (3), and the speed adjustment of the hoisting operation of the hook (34) can also be performed.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-043651 filed on March 17, 2021. The entire contents of the Japanese application are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to a crane. BACKGROUND

[0003] In Patent Literature 1, there is proposed a method in which a GNSS (Global Navigation Satellite System) receiver is installed on a boom front end portion and a hook, and position adjustment of the boom front end portion is performed before start of hoisting so that the position of the boom front end portion when viewed from above coincides with the position of the hook when viewed from above.

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2020-169087

[0005] When the crane starts hoisting of a load, if the hook is not directly above the center of gravity of the load, the posture of the load can change from the start of hoisting, resulting in a positional deviation between the boom front end portion and the hook.

[0006] However, the above-described conventional crane does not deal with the positional deviation between the boom front end portion and the hook that occurs after the start of hoisting of the load. SUMMARY

[0007] An object of the present application is to effectively deal with the positional deviation between the boom front end portion and the hook that occurs from the start of hoisting of the load.

[0008] The present application is a crane having a boom and hoisting a load from the front end of the boom via a hook, which is configured to perform position adjustment control that brings the position of the hook and the position of the front end of the boom close to each other when viewed from the vertical direction during a period from the start of hoisting operation until the load leaves the ground surface.

[0009] According to the present application, the positional deviation between the front end of the boom and the hook that occurs from the start of hoisting of the load can be effectively dealt with. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a side view of a crane according to an embodiment of the present application.

[0011] Figure 2 is a schematic plan view of an upper slewing body of a crane.

[0012] Figure 3 is a block diagram showing the structure of a control device of a crane and its surroundings.

[0013] Figure 4 This is a flowchart of the position adjustment control.

[0014] Figure 5 This is an explanatory diagram showing the state in which the relative position of the hook relative to the boom changes when viewed from above during the hoisting operation.

[0015] Figure 6 This is an explanatory diagram showing the change in the relative position of the hook with respect to the boom when viewed from above, towards the upper rotating body.

[0016] Figure 7 This is an explanatory diagram showing the change in the relative position of the hook with respect to the boom when viewed from above, towards the side opposite to the upper rotating body (the side opposite to the main body of the crane).

[0017] Figure 8 This is a side view of a crane that shows the reason for the relative positional deviation of the hook relative to the front end of the boom when viewed from above.

[0018] Figure 9 This is an example of a display showing operating instructions for operators on the status display screen of a crane displayed on a display device.

[0019] In the diagram: 1-Crane, 2-Lower traveling body, 3-Upper slewing body, 4-Boom, 5-Counterweight, 32-Winding rope, 33-Operator's cab, 34-Hook, 36-Winding hoist, 37-Irregular rope, 42-Irregular winch, 44-Hanging rope, 60-Control device, 61-Controller, 611-Position adjustment control unit, 621-Input unit, 622-Display device, 624-Operating lever, 632-Boom angle sensor, 633-Slewing sensor, 635-Control valve, 641~643-Position measuring unit, m1, m2-Indication messages. Detailed Implementation

[0020] [Outline structure of a crane]

[0021] Figure 1 This is a side view of crane 1. Figure 2 This is a schematic top view of the upper rotating body 3 of crane 1. Crane 1 is a so-called mobile crawler crane. Regarding crane 1, see the following description: Figure 2 As shown, the forward, backward, left, and right directions in the line of sight of a passenger riding on the upper rotating body 3, which is the main body of the crane, will be described as the forward, backward, left, and right directions of the crane 1. In addition, unless otherwise specified, the directions of each part will be described in principle as if the lower traveling body 2 is in a state where its forward and backward direction is consistent with the forward and backward direction of the upper rotating body 3 (set as the reference posture).

[0022] Furthermore, in the following description, it is assumed that the crane 1 is located on a horizontal plane, and "view from above" means the state of observation from a direction perpendicular to the horizontal plane where the crane 1 is located (i.e., the vertical direction).

[0023] like Figure 1 As shown, the crane 1 is configured to include a self-propelled tracked lower traveling body 2, an upper slewing body 3 rotatably mounted on the lower traveling body 2, and a boom 4 that is undulatingly mounted on the front side of the upper slewing body 3.

[0024] The lower traveling body 2 includes a main body 21 and tracks 22 disposed on the left and right sides of the main body 21. The left and right tracks 22 are driven to rotate by hydraulic motors (not shown).

[0025] On the front side of the upper rotating body 3, the boom 4 is mounted in an undulating manner. Near the front end of the upper side of the boom 4, a pulley 43 for guiding the winch rope 32 is rotatably mounted.

[0026] Furthermore, the lower end of the mast 31 is supported at a position further rearward than the boom 4 on the upper rotating body 3.

[0027] Furthermore, the upper rotating body 3 is driven by a rotating hydraulic motor (not shown) to rotate relative to the lower traveling body 2 about a vertical axis.

[0028] A counterweight 5 is installed at the rear of the upper rotating body 3 to maintain weight balance between the boom 4 and the load L. The number of counterweights 5 can be increased or decreased as needed.

[0029] Near the counterweight 5, there is an undulating winch 42 that causes the boom 4 to undulate. In front of the winch 4, there is a hoisting winch 36 that winds up or winds out the hoisting rope 32. The hoisting winch 36 is driven by a hoisting hydraulic motor (not shown) to wind up or wind out the hoisting rope 32, thereby hoisting or winding out the hook 34 and the load.

[0030] Furthermore, an operator's cab 33 is located on the right front side of the upper rotating body 3.

[0031] The mast 31 has an upper spreading device 35 at its upper end, which is connected to the other end of the boom tension rope 44, one end of which is connected to the upper end of the boom 4. A lower spreading device (not shown) is located below the upper spreading device 35. If the undulating winch 42 winds up or unwinds the undulating rope 37 wound multiple times between the upper and lower spreading devices, the interval between them changes, causing the boom 4 to undulate. The undulating winch 42 is driven by an undulating hydraulic motor (not shown).

[0032] [Crane control system]

[0033] The crane's control device 60 is attached to the operator's cab 33 of the upper rotating body 3. Figure 3 This is a block diagram showing the control device 60 and its surrounding structure. The control device 60 is a control terminal mounted on the crane 1, mainly controlling various actions of the crane 1 such as traveling, rotating, hoisting and unhooking of loads.

[0034] The control device 60 includes a controller 61, which includes an arithmetic processing unit, a CPU, a storage device (i.e., ROM and RAM), and other peripheral circuits.

[0035] The controller 61 includes a software module for a position adjustment control unit 611, which performs position adjustment control of the front end of the boom 4 and the hook 34 (described later). Alternatively, the position adjustment control unit 611 can also be configured in hardware.

[0036] The controller 61 is connected to an input unit 621, a display device 622, an alarm 623, an operating lever 624, and a memory 625, which together constitute the control device 60.

[0037] Furthermore, the controller 61 is connected to a force sensor 631, a boom angle sensor 632, a slewing sensor 633, a control valve 635, and position measuring units 641 to 643.

[0038] The input unit 621 is, for example, an input interface such as a touch panel, which outputs control signals corresponding to the operations from the operator to the controller 61. The operator can operate the input unit 621 to perform various inputs required for setting or manipulating the boom length, the weight of the load, and other settings.

[0039] The display device 622, for example, includes a touch panel display that also serves as an input unit 621. Based on control signals output from the controller 61, it displays information such as the weight of the suspended load, the boom angle, and the rotation angle of the upper slewing body 3 on the display screen (see reference). Figure 9 ).

[0040] Alarm 623 issues an alarm based on the control signal output from controller 61.

[0041] The control lever 624 is used to manually input various operations to make the crane 1 perform various actions, and the control signal corresponding to the operation amount of the control lever 624 is input to the controller 61.

[0042] For example, the control lever 624 can input the movement of the lower traveling body 2, the rotation of the upper rotating body 3, the undulating movement of the boom 4, and the lifting and lowering of the suspended object.

[0043] Force sensor 631 is installed on the upper lifting device 35. It detects the tension of the boom rope 44 that causes the boom 4 to rise and fall, and outputs a control signal corresponding to the detected tension to the controller 61.

[0044] A boom angle sensor 632 is mounted on the base end side of the boom 4. It detects the undulation angle of the boom 4 (hereinafter also referred to as the boom angle) and outputs a control signal corresponding to the detected boom angle to the controller 61. The boom angle sensor 632 detects, for example, the angle relative to the horizontal plane (i.e., the angle relative to the ground) as the boom angle.

[0045] A rotation angle sensor 633 is installed between the lower traveling body 2 and the upper rotating body 3. It detects the rotation angle of the upper rotating body 3 and outputs a control signal corresponding to the detected rotation angle to the controller 61. For example, the rotation angle is detected by the rotation angle centered on the vertical axis.

[0046] The control valve 635 consists of multiple valves that can be switched according to the control signal from the controller 61.

[0047] For example, the control valve 635 includes valves that control the rotation drive of the left and right tracks 22 of the lower walking body 2, valves that control the rotation of the upper rotating body 3, valves that control the rotation drive of the undulating winch, and valves that control the rotation drive of the hoisting winch, etc.

[0048] Positioning units 641, 642, and 643 are respectively installed in the operator's cab 33 of the upper rotating body 3, near the front end of the boom 4, and on the hook 34. They are composed of GNSS receivers that detect their respective positions. In addition, the positioning unit 641 is not limited to being installed on the operator's cab 33, but can also be installed at any position on the upper rotating body 3.

[0049] Each measuring unit 641 to 643 measures the current position (latitude, longitude, altitude) of its respective installation location and periodically outputs the measuring data, representing the current position, to the controller 61.

[0050] Additionally, in the following description, "the front end of the boom 4" refers to the position where the winch rope 32 begins to hang from the boom 4 toward the hook 34. Figure 2 The symbol C in the text.

[0051] When viewed from above (projected onto a horizontal plane), the measuring part 642, which is installed near the front end of the boom 4, is slightly separated from the "front end of the boom 4," and their positions are not strictly consistent.

[0052] On the other hand, the relative positional relationship between the positions of the measuring parts 641 and 642 and the "front end of the boom 4" is known. Therefore, the controller 61 calculates the position of the "front end of the boom 4" when viewed from above, based on the positions of the measuring parts 641 and 642 and the undulation angle of the boom 4.

[0053] In the following description, the position of the "front end of boom 4" when viewed from above is referred to as the "front end position of boom", and the position of the "hook 34" when viewed from above is referred to as the "hook position".

[0054] Furthermore, the "hook position" can be the installation position of the measuring part 643 on the hook 34, or it can be the position of the center of gravity of the hook 34. When the hook position and the installation position of the measuring part 643 are inconsistent, the control device 60 preferably has their relative positional relationship as the setting data.

[0055] [Position Adjustment Control]

[0056] according to Figures 1 to 8 The position adjustment control based on the position adjustment control unit 611 will be described in detail.

[0057] Figure 4 This is a flowchart of the position adjustment control. Figure 5 This is an explanatory diagram showing the state in which the relative position of the hook 34 with respect to the boom 4 changes when viewed from above during the hoisting operation of the load L without any change in position. Figure 6 This is an explanatory diagram showing the changing relative position of the hook 34 with respect to the boom 4 when viewed from above, towards the upper rotating body 3 (crane main body side). Figure 7 This is an explanatory diagram showing the state in which the relative position of the hook 34 with respect to the boom 4 changes towards the side opposite to the upper rotating body 3 (the side opposite to the crane body side) when viewed from above. Additionally, in Figures 5 to 7 The illustration of the suspended object L is omitted.

[0058] The position adjustment control is to reduce the motion control of the position change if the relative position of the hook 34 with respect to the boom 4 changes during the period from the start of the hoisting action of the load L until the load L leaves the ground.

[0059] like Figure 4 As shown, when hoisting the load L, the hook 34 is connected to the load L. For example, if the hoisting action is executed by inputting the input unit 621 (step S1), the hoisting winch 36 is driven to start hoisting (step S3).

[0060] In addition, before starting to drive the winch 36, the operator can make a pre-positioning adjustment using the operating lever 624 so that the front end of the boom 4 is directly above the hook 34 to which the load L is attached.

[0061] If the hoisting operation begins, the position adjustment control unit 611 obtains the position coordinates of the control room 33 of the upper rotating body 3, the front end of the boom 4 and the hook 34 from the positioning data of each measuring unit 641 to 643 (step S5).

[0062] In addition, the position adjustment control unit 611 unfolds the crane coordinate system onto the horizontal plane of the upper rotating body 3 of the crane 1 and calculates the position coordinates of each measuring unit 641 to 643 projected onto the crane coordinate system.

[0063] Here, as Figure 2 As shown, the crane coordinate system is an orthogonal coordinate system unfolded on a horizontal plane, consisting of a front-to-back axis parallel to the length direction of the boom 4 when viewed from above, and a left-to-right axis orthogonal to the front-to-back axis.

[0064] The position adjustment control unit 611 calculates the position of the boom tip and the hook position in the crane coordinate system from the position coordinates of each measuring unit 641 to 643. Then, it calculates the deviation between the boom tip position and the hook position (step S7).

[0065] Furthermore, the position adjustment control unit 611 determines whether there is a deviation between the boom tip position and the hook position based on the above calculation (step S9). At this time, a threshold value is preferably preset for the amount of deviation between the boom tip position and the hook position. Therefore, if the calculated deviation is less than the threshold value, the position adjustment control unit 611 determines that the boom tip position and the hook position are consistent; if it is greater than or equal to the threshold value, it determines that there is a deviation between the boom tip position and the hook position.

[0066] Furthermore, if it is determined that there is a deviation between the boom tip position and the hook position ("Yes" in step S9), the position adjustment control unit 611 performs at least one of the following actions: the boom 4's up-and-down movement and the upper slewing body's rotation, to bring the boom tip position and the hook position closer to each other (step S11). At this time, the winch speed can also be adjusted.

[0067] Then, proceed to step S13.

[0068] Furthermore, if it is determined that there is no deviation between the boom front position and the hook position ("No" in step S9), the position adjustment control unit 611 skips step S11 and proceeds to step S13.

[0069] Then, in step S13, the position adjustment control unit 611 determines whether the suspended object L is in a state of being off the ground. Being off the ground means that all parts of the suspended object L have been removed from the ground contact area (ground) by the winch.

[0070] The position adjustment control unit 611 can determine whether the position is off the ground after a specified time has elapsed since the start of hoisting, or it can determine whether the position is off the ground after a specified hoisting amount has been reached since the start of hoisting.

[0071] Then, if it is determined that the load L has not yet left the ground, the position adjustment control unit 611 returns the process to step S5, obtains the current position coordinates of the control room 33 of the upper rotating body 3, the front end of the boom 4 and the hook 34 again, and repeats the subsequent steps S5 to S13.

[0072] Furthermore, if it is determined that the suspended object L has already left the ground, the position adjustment control unit 611 terminates the position adjustment control.

[0073] Alternatively, it is not necessary to strictly end position adjustment control when the object leaves the ground; it is sufficient to end position adjustment control at least after the object leaves the ground.

[0074] Furthermore, in step S13, the position adjustment control ends, but the hoisting action of the suspended object L continues.

[0075] Next, we will further explain in detail the multiple states of deviation between the boom front end position and the hook position in step S9 of the above position adjustment control, as well as the motion control of boom 4 undulating and lifting motion, upper slewing body 3 slewing motion and winch speed adjustment performed in each state.

[0076] like Figure 5 As shown, when the hook 34 is located directly below the front end of the boom 4 (i.e., the ideal state where the front end of the boom is aligned with the hook position), the position adjustment control unit 611 does not need to change the undulation angle of the boom 4 or the rotation angle of the upper rotating body 3, and maintains the preset hoisting speed Pu to perform the hoisting action of the load L.

[0077] On the other hand, sometimes when viewed from above, the position of the hook may deviate from the front end of the boom towards the rear. Figure 6 When viewed from above, the position of the hook deviates forward relative to the front end of the boom. Figure 7 And when viewed from above, the position of the hook deviates to the left or right relative to the front end of the boom. Figure 2 The hook 34 is represented by a double-dotted line.

[0078] One of the reasons for this is as follows: Figure 8 Arrow a indicates the forward tilting of the upper rotating body 3 of the crane 1 or the deflection of the boom 4 caused by the weight of the load L. At this time, when viewed from above, the position of the hook deviates rearward relative to the front end of the boom.

[0079] Furthermore, other reasons can be cited such as Figure 8 Arrow b indicates that, in a top-down view at the start of the hoisting operation, the relative position of the hook 34 deviates from the center of gravity g of the suspended load L. At this time, the hoisting causes the suspended load L to tilt, and consequently, the hook 34 is pulled and moved by the suspended load L, resulting in a deviation. Under these circumstances, the initial direction of the hook's position deviation relative to the center of gravity g of the suspended load L determines the direction of deviation after the start of hoisting; therefore, deviation can occur in any direction on the horizontal plane.

[0080] like Figure 6 As shown, when viewed from above, if the hook position deviates rearward relative to the boom tip position, the position adjustment control unit 611 drives the undulating winch 42 to cause the boom 4 to undulate upward in the direction of arrow Bu. This causes the boom tip position to move rearward, thus reducing or eliminating the deviation between the boom tip position and the hook position.

[0081] At this time, as the boom 4 rises and falls, the hook 34 will rise upwards. Therefore, the position adjustment control unit 611 performs operation control of the winch 36 to decelerate the specified winch speed Pu by adjusting the speed Ad in the opposite direction of the winch direction, so as to prevent the winch action of the suspended object L from accelerating rapidly.

[0082] In addition, regarding the adjustment speed Ad, its size can be determined based on the relative deviation between the front end position of the boom and the position of the hook in the forward and backward directions when viewed from above.

[0083] For example, regarding the deviation between the boom front position and the hook position and the adjustment speed Ad, a data table showing the corresponding relationship can be prepared, and the adjustment speed Ad can be determined by referring to the data table.

[0084] Furthermore, the relationship between the deviation between the boom tip position and the hook position and the adjustment speed Ad can be quantified and the adjustment speed Ad can be calculated from the deviation.

[0085] In these situations, the absolute value of the adjustment speed Ad in the direction opposite to the hoisting direction may sometimes be greater than the specified hoisting speed Pu. In this case, the hoist 36 is driven in the winding direction instead of the hoisting direction.

[0086] like Figure 7 As shown, when viewed from above, if the hook position deviates forward relative to the boom tip position, the position adjustment control unit 611 drives the undulating winch 42 to cause the boom 4 to undulate and descend in the direction of arrow Bd. This causes the boom tip position to move forward, thus reducing or eliminating the deviation between the boom tip position and the hook position.

[0087] At this time, as the boom 4 descends, the hook 34 will descend downwards. Therefore, the position adjustment control unit 611 performs operation control of the winch 36 to accelerate the adjustment of the specified winch speed Pu by adjusting the winch direction speed Au, so as to prevent the winch speed of the suspended object L from decreasing or the suspended object L from colliding with the ground.

[0088] Regarding the adjustment speed Au, its value can also be determined based on the relative deviation between the front end of the boom and the hook position in the forward and backward directions when viewed from above.

[0089] At this point, regarding the deviation between the boom front position and the hook position and the adjustment speed Au, the adjustment speed Au can be determined using data from a data table representing the corresponding relationship, or the relationship between the deviation between the boom front position and the hook position and the adjustment speed Au can be quantified to calculate the adjustment speed Ad.

[0090] like Figure 2 As shown, when viewed from above, if the hook position deviates to the left or right relative to the boom tip position, the position adjustment control unit 611 drives the slewing hydraulic motor to rotate the upper slewing body 3 and the boom 4 to the right or left. The amount of rotational motion is preferably set to be equal to the amount that counteracts the deviation to the left or right.

[0091] As a result, the deviation between the front end of the boom and the hook position is reduced or eliminated.

[0092] Furthermore, the relative deviation of the hook position from the front end of the boom when viewed from above can sometimes occur simultaneously in both the front-to-back and left-to-right directions.

[0093] At this point, it is only necessary to proceed in parallel. Figure 6 or Figure 7 Position adjustment in the front and rear directions as shown Figure 2 Simply adjust the position in the left and right directions as shown.

[0094] [Technical Effects of Embodiments of the Invention]

[0095] As described above, the controller 61 of the control device 60 of the crane 1 includes a position adjustment control unit 611, which performs position adjustment control to bring the position of the hook and the front end of the boom closer to each other when viewed from the vertical direction from the start of the hoisting operation until the load L leaves the ground.

[0096] Therefore, in crane 1, the positional deviation between the boom tip position and the hook position that occurs after the hoisting of the load L begins can be effectively reduced. Moreover, this effectively suppresses the swaying of the load L after it leaves the ground.

[0097] Furthermore, the position adjustment control unit 611 detects the direction of movement of the hook 34 relative to the upper rotating body 3 to perform position adjustment control, thus enabling more accurate reduction of positional deviation between the boom front position and the hook position.

[0098] Furthermore, the position adjustment control unit 611 adjusts the lifting and lowering of the boom 4 and the speed of the hoisting action of the hook 34 according to the direction of movement of the hook 34 relative to the crane body during position adjustment control.

[0099] Therefore, by the undulating motion of the boom 4, the positional deviation between the boom front end and the hook position after the start of hoisting can be effectively reduced, and the change in hoisting speed caused by the undulating motion of the boom 4 can be suppressed.

[0100] In particular, during position adjustment control, if the hook 34 moves relative to the side (rear) of the upper rotating body 3, the position adjustment control unit 611, together with the undulating upward movement of the boom 4, adjusts the speed of the hook 34's winch movement to either reduce the winch speed (including reducing it to zero) or switch the winch movement to a winding-out movement. Thus, through the undulating movement of the boom 4, the positional deviation between the boom tip position and the hook position after the start of winch is effectively reduced. Furthermore, it prevents the winch speed of the load L from increasing abruptly due to the undulating upward movement of the boom 4, thereby enabling stable winch operation.

[0101] Furthermore, during position adjustment control, if the hook 34 moves to the side opposite to the upper rotating body (front), the position adjustment control unit 611 adjusts the speed of the hook 34's winch motion to increase the winch speed, in conjunction with the undulating and lowering motion of the boom 4. Thus, through the undulating motion of the boom 4, the positional deviation between the boom tip position and the hook position after the start of winch is effectively reduced. Moreover, it prevents the winch of the load L from slowing down drastically due to the undulating and lowering motion of the boom 4, thereby enabling stable winch operation.

[0102] Furthermore, during position adjustment control, if the hook 34 moves relative to the boom 4 to either the left or right side, the position adjustment control unit 611 rotates the upper slewing body 3 in that direction of movement. Therefore, it can effectively reduce the left-right positional deviation between the boom tip position and the hook position after the start of hoisting.

[0103] Furthermore, by performing the rotation of the upper rotating body 3 in parallel with the lifting and lowering of the boom 4, it is possible to cope with the all-round relative positional deviation between the boom front end position and the hook position after the start of hoisting.

[0104] [other]

[0105] Without departing from the spirit of the invention, the specific structure shown in the embodiments of the invention described above may be appropriately modified.

[0106] For example, in the position adjustment control described above, an example is shown where the boom 4 rises and falls, the upper slewing body 3 rotates, and the hook 34 is wound out by the position adjustment control unit 611 after the hoisting of the load L is started, without relying on the operation of the operator.

[0107] Alternatively, the aforementioned actions can also be performed by a staff member. In this case, the position adjustment control unit 611 preferably provides operation instructions to the staff member via, for example, a display device 622.

[0108] Figure 9 This is an example of a display screen G showing the status of crane 1 on display device 622.

[0109] For example, if a horizontal deviation occurs between the boom tip position and the hook position during the period from the start of the hoisting operation until the load L leaves the ground, the position adjustment control unit 611 displays instruction messages m1 and m2 on the status display screen G for providing operational instructions to the operator. Figure 9 The example illustrates a display as described above. Figure 6 The example shown is the case where the hook position deviates from the rearward position relative to the front end of the boom, indicating the boom 4 to rise and fall, and the example shown is the case where the boom 4 rises and falls ...

[0110] In addition to the examples mentioned above, in such Figure 7 When the hook position is deviated from the forward position relative to the front end of the boom, or as shown... Figure 2 If the position of the hook shown deviates to the left or right relative to the front end of the boom, an instruction message indicating the corresponding action can be displayed.

[0111] Furthermore, as an instruction for staff, it is not limited to displaying the instruction on the display device 622; any mechanism that staff can recognize, such as lighting up a light to indicate the instruction or a voice message based on a voice output mechanism, may also be used.

[0112] Furthermore, the boom 4 is raised and lowered by the controller 61, but the winch speed can also be accurately adjusted by the controller 61.

[0113] Furthermore, the position adjustment control described above is applicable to all types of cranes that lift loads, including bridge cranes, jib cranes, truck cranes, crab cranes, and wheeled cranes. That is, it is also applicable to cranes that have a supporting hook beam as a non-undulating boom.

[0114] Furthermore, the position adjustment control used to bring the position of the hook and the position of the front end of the boom closer to each other is not limited to the rotation of the boom, but can also be performed by the extension and retraction of the boom, just like in telescopic cranes.

Claims

1. A crane having a movable boom and hoisting a load from a front end of the movable boom via a hook, the crane characterized by, during a period from the start of a hoisting operation until the load departs from a ground surface, performing position adjustment control that brings the position of the hook and the position of the front end of the movable boom close to each other when viewed from a vertical direction, performing the position adjustment control in accordance with the direction of relative movement of the hook with respect to the crane main body during the period from the start of the hoisting operation until the load departs from the ground surface, in the position adjustment control, performing either of raising and lowering of a heave operation of the movable boom in accordance with the direction of relative movement of the hook with respect to the crane main body, and performing speed adjustment of the hoisting operation of the hook in accordance with the direction of relative movement of the hook with respect to the crane.

2. The crane according to claim 1, characterized by, in the position adjustment control, if the hook moves to the side of the crane main body, causing the movable boom to perform a heave raising operation, and causing the hoisting speed of the hoisting operation of the hook to be reduced or switching the hoisting operation of the hook to a winding-out operation in accordance with the speed of raising of the hook caused by the heave raising operation.

3. The crane according to claim 1 or 2, characterized by, in the position adjustment control, if the hook moves to the side opposite to the side of the crane main body, causing the movable boom to perform a heave lowering operation, and causing the hoisting speed of the hoisting operation of the hook to be increased in accordance with the speed of lowering of the hook downward caused by the heave lowering operation.

4. The crane according to claim 1 or 2, characterized by, in the position adjustment control, if the hook moves to either of the left and right sides with respect to the movable boom, causing the crane main body to perform a turning operation toward the direction of the movement.

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