Bucket control device for construction machinery

Abstract

To provide a bucket control device that is able to perform an opening / lowering operation with a simple operation in a construction machine and is able to prevent a bucket device from being closed during an opening / lowering operation even when a condition relating to a brake characteristic changes.SOLUTION: A bucket control device includes: an opening / closing state determination unit 71 that determines whether a bucket device 10 is in an open state or not; and brake force adjustment mechanisms 62, 64, 72 that, when a control mode is set to a synchronization control mode, such a first brake operation as to reduce first brake force is applied to a first brake operation device 52, and the opening / closing state determination unit 71 determines that the bucket device 10 is in the opening state, performs opening / lowering control, which is control for adjusting the first brake force and second brake force so that the bucket device 10 lowers by its own weight while an opening state of the bucket device 10 is maintained.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a bucket control device for controlling the operations of a first winch drum and a second winch drum in a construction machine such as a crane to open and close and raise and lower a bucket device.

Background Art

[0002] Among conventional construction machines, there are known ones equipped with a bucket device that can be opened and closed and raised and lowered, such as a clam shell bucket. Such a construction machine includes a first winch drum and a second winch drum for opening and closing and raising and lowering the bucket device, a first winch operation lever to which an operation for operating the first winch drum is given, a second winch operation lever to which an operation for operating the second winch drum is given, a first brake operation pedal for adjusting the braking force on the first winch drum, and a second brake operation pedal for adjusting the braking force on the second winch drum.

[0003] In order to cause the bucket device to perform various operations including, for example, an "open and lower" operation in which the bucket device is lowered while maintaining an open state, the operator of the construction machine needs to simultaneously perform a plurality of operations among the operations of the first winch operation lever, the operation of the second winch operation lever, the operation of the first brake operation pedal, and the operation of the second brake operation pedal. Performing such a plurality of operations simultaneously takes time for an unskilled operator who is not proficient in operating the construction machine, and also involves fatigue for a skilled operator who is proficient in operating the construction machine.

[0004] In order to solve the above problems, Patent Document 1 discloses a drive control device for a winch that enables various operations of a packet by the forward and reverse rotation of a support drum and a drive motor for an opening and closing drum, and the forward and backward swing of an operation lever, and separately provided push button switch operations.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, when the opening and lowering operation is performed among the various operations of the bucket device, there is a problem that the posture of the bucket device is likely to change from the open state to the closing direction during this opening and lowering operation. In the winch drive control device of Patent Document 1, such a problem is not considered at all.

[0007] Patent Document 2 discloses a winch drive control device that controls the braking force acting on the first winch device and the second winch device according to a preset braking characteristic representing the relationship between the operation amount of the braking command means and the braking force acting on the first winch device and the second winch device. However, when changes in conditions such as changes in the braking torque due to changes in the temperature of the hydraulic oil and changes in the specifications of the bucket device attached to the winch rope occur, the preset braking characteristic and the actually required braking characteristic may not always match. Therefore, in the drive control device of Patent Document 2, when a change in conditions related to the braking characteristic occurs as described above, the bucket device may close during the opening and lowering operation.

Means for Solving the Problems

[0008] The present disclosure aims to solve the above problems. That is, the present disclosure provides a bucket control device for a construction machine that can perform the opening-down operation with a simple operation, and can suppress the bucket device from closing during the opening-down operation even when a change in conditions related to the brake characteristics occurs.

[0009] Provided is a bucket control device for a construction machine including a first winch drum that pays out and winds up a first winch rope, a second winch drum that pays out and winds up a second winch rope, and a bucket device that is connected to the first winch rope and the second winch rope and can be opened and closed and lifted and lowered in response to the rotation of the first winch drum and the rotation of the second winch drum. The bucket control device includes a clutch brake mechanism that can put the first winch rope and the second winch rope in a free state in which they can be paid out from the first winch drum and the second winch drum by the weight of the bucket device, a clutch brake mechanism that can apply a first braking force and a second braking force to the first winch drum and the second winch drum respectively, a first brake operating device provided with a first brake operation for adjusting the first braking force, a second brake operating device provided with a second brake operation for adjusting the second braking force, a control mode setting unit that can set the control mode to a synchronous control mode in which the first braking force and the second braking force can be adjusted based on the first brake operation, an opening / closing state determination unit that determines whether the bucket device is in an open state, and a brake force adjustment mechanism that performs opening-down control, which is a control for adjusting the first braking force and the second braking force so that the bucket device descends by its own weight while maintaining the open state of the bucket device when the control mode is set to the synchronous control mode, a first brake operation for reducing the first braking force is applied to the first brake operating device, and the opening / closing state determination unit determines that the bucket device is in the open state.

[0010] In this bucket control device, the open / closed state determination unit actually determines the open state of the bucket device, and the first and second brake forces are adjusted so that the bucket device descends under its own weight while maintaining this actually determined open state. As a result, even if conditions related to the brake characteristics change, such as a change in brake torque due to a change in hydraulic oil temperature or a change in the specifications of the bucket device attached to the first and second winch ropes, the first and second brake forces can be adjusted to suit the actual situation at that time, and the bucket device can be prevented from closing during the opening and lowering operation. Moreover, in this bucket control device, when the operator causes the bucket device to perform the opening and lowering operation, the operator can adjust the first and second brake forces based on the operation of the first brake by setting the control mode to the synchronous control mode, eliminating the need to operate the second brake. The braking force adjustment mechanism automatically executes the opening and lowering control when the following determination conditions are met: the control mode is set to the synchronous control mode, a first brake operation that reduces the first braking force is applied to the first brake operation device (the first braking force is weakened), and the opening and closing state determination unit determines that the bucket apparatus is in the open state. This allows the operator to cause the bucket apparatus to perform the opening and lowering operation with a simple operation.

[0011] In the bucket control device, the opening / closing state determination unit can further determine whether the bucket device is in the closed state. The braking force adjustment mechanism performs closing-lowering control, which is control for adjusting the first braking force and the second braking force so that the bucket device descends under its own weight while maintaining the closed state of the bucket device when the control mode is set to the synchronization control mode, the first braking operation for reducing the first braking force is given to the first braking operation device, and the opening / closing state determination unit determines that the bucket device is in the closed state. With this configuration, even when a change in conditions related to braking characteristics occurs, it becomes possible to adjust the first and second braking forces according to the actual situation at that time. Therefore, the operator can surely cause the bucket device to perform the opening-lowering operation.

[0012] Specifically, the first winch rope is an opening / closing rope for opening and closing the bucket device, the second winch rope is a support rope for supporting the bucket device, the first winch drum is an opening / closing drum for paying out and winding up the opening / closing rope, the second winch drum is a support drum for paying out and winding up the support rope, the clutch brake mechanism includes a first clutch brake capable of applying the first braking force to the first winch drum and a second clutch brake capable of applying the second braking force to the second winch drum, the brake force adjustment mechanism includes a first proportional valve for brake that outputs a first pilot pressure for adjusting the first braking force to the first clutch brake, a second proportional valve for brake that outputs a second pilot pressure for adjusting the second braking force to the second clutch brake, and in the opening-down control, it preferably includes a brake force adjustment unit that gives commands to the first proportional valve for brake and the second proportional valve for brake so that the second braking force becomes higher than the first braking force by a preset ratio or more. In this configuration, the first and second braking forces are adjusted so that the second braking force on the support drum (the second winch drum) for paying out and winding up the support rope (the second winch rope) becomes higher than the first braking force on the opening / closing drum (the first winch drum) for paying out and winding up the opening / closing rope (the first winch rope) by the preset ratio or more. Thereby, the bucket device can be made to perform the opening-down operation more reliably.

[0013] The bucket control device further includes a first detector for detecting a first payout amount which is the payout amount of the first winch rope, and a second detector for detecting a second payout amount which is the payout amount of the second winch rope. The opening / closing state determination unit may be configured to determine the opening / closing state of the bucket device based on the difference between the first payout amount and the second payout amount. In this configuration, since the opening / closing state of the bucket device is determined based on the difference between the first payout amount and the second payout amount, the opening / closing state can be determined relatively accurately.

[0014] In the bucket control device, in the lowering control, the braking force adjustment mechanism sets a target value of the opening degree of the bucket device or a target value of a value corresponding to the opening degree based on the opening / closing state of the bucket device determined by the opening / closing state determination unit, calculates a deviation between the actual opening degree of the bucket device or a value corresponding thereto and the target value, and preferably performs control to reduce the deviation by feeding back the deviation. In this configuration, since feedback control for reducing the deviation is performed, even when a change in conditions related to braking characteristics occurs, it becomes possible to more appropriately adjust the first and second braking forces to match the actual situation at that time. Therefore, it is possible to more reliably suppress the bucket device from closing during the lowering operation.

[0015] The bucket control device further includes a first winch operation device provided with a first payout operation for rotating the first winch drum so as to pay out the first winch rope and a first winding operation for rotating the first winch drum so as to wind up the first winch rope, a second winch operation device provided with a second payout operation for rotating the second winch drum so as to pay out the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope, and a drum operation control unit. The clutch brake mechanism is configured to be switchable between the free state and a connected state in which a driving force for driving the first winch drum and the second winch drum can be transmitted to the first winch drum and the second winch drum. In the synchronization control mode, when the clutch brake mechanism is in the connected state, the operations of the first winch drum and the second winch drum can be controlled based on one of the first payout operation and the first winding operation. The drum operation control unit controls the operations of the first winch drum and the second winch drum such that the bucket device descends while maintaining the open / closed state of the bucket device when the control mode is set to the synchronization control mode and the first payout operation is given to the first winch operation device, and controls the operations of the first winch drum and the second winch drum such that the bucket device ascends while maintaining the open / closed state of the bucket device when the control mode is set to the synchronization control mode and the first winding operation is given to the first winch operation device. In this configuration, when the clutch brake mechanism is set to the connected state in which the driving force, such as a winch motor, can be transmitted to the first and second winch drums, the operator can lower or raise the bucket device using the driving force while maintaining the open / closed state of the bucket with a simple operation.

[0016] The bucket control device further includes a first winch operating device provided with a first payout operation for rotating the first winch drum so as to pay out the first winch rope and a first winding operation for rotating the first winch drum so as to wind up the first winch rope, and a second winch operating device provided with a second payout operation for rotating the second winch drum so as to pay out the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope. The control mode setting unit is configured to be able to set the control mode to any one of a plurality of modes including the synchronous control mode and the asynchronous control mode. When the control mode is set to the asynchronous control mode and the first winding operation is given to the first winch operating device, the brake force adjustment mechanism preferably performs bucket stationary closing control, which is control to operate the bucket device in a closing direction while maintaining the height of the bucket device. In this configuration, the operator can operate the bucket device in a closing direction while easily maintaining the height of the bucket device in the air with a simple operation.

[0017] The bucket control device further includes a first winch operation device provided with a first payout operation for rotating the first winch drum so as to pay out the first winch rope and a first winding operation for rotating the first winch drum so as to wind up the first winch rope, and a second winch operation device provided with a second payout operation for rotating the second winch drum so as to pay out the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope. The control mode setting unit is configured to be able to set the control mode to any one of a plurality of modes including the synchronous control mode and the asynchronous control mode. The braking force adjustment mechanism performs excavation control, which is a control to operate the bucket device in the closing direction and reduce the second braking force in response to a decrease in the operation amount of the first braking operation device when the control mode is set to the asynchronous control mode, the first winding operation is given to the first winch operation device, and the first braking operation device is operated to reduce the first braking force. In this configuration, the operator can operate the bucket device in the closing direction with a simple operation and reduce the second braking force in response to a decrease in the operation amount of the first braking operation device. In this excavation control, when the bucket device excavates earth and sand during the excavation work, the bucket device operates so as to sink downward in response to the excavation, so that the bucket device can grasp more earth and sand than in the bucket stationary closing control.

[0018] The bucket control device further includes a first winch operating device provided with a first payout operation for rotating the first winch drum so as to pay out the first winch rope and a first winding operation for rotating the first winch drum so as to wind up the first winch rope, and a second winch operating device provided with a second payout operation for rotating the second winch drum so as to pay out the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope. The control mode setting unit is configured to be able to set the control mode to any one of a plurality of modes including the synchronous control mode and the asynchronous control mode. When the control mode is set to the asynchronous control mode, neither the first payout operation nor the first winding operation is given to the first winch operating device, and when the first brake operating device is operated to reduce the first braking force, it is preferable to perform bucket stationary opening control, which is control to operate the bucket device in the opening direction while maintaining the height of the bucket device. In this configuration, the operator can operate the bucket device in the opening direction while easily maintaining the height of the bucket device in the air with a simple operation.

Advantages of the Invention

[0019] As described above, according to the present disclosure, in a construction machine, the operation of opening and lowering the bucket device can be performed with a simple operation, and moreover, even when a change in conditions related to the brake characteristics occurs, a bucket control device that can suppress the bucket device from closing during the opening and lowering operation is provided.

Brief Description of the Drawings

[0020] [Figure 1] It is a side view showing a crane equipped with the bucket control device according to the embodiment of the present disclosure. [Figure 2] It is a block diagram showing an outline of the functional configuration of the bucket control device. [Figure 3] FIG. 2 is a diagram showing a hydraulic circuit provided in the crane. [Figure 4] 4A and 4B are diagrams for explaining the opening and closing operation of a bucket device provided in the crane. [Figure 5] 5 is a diagram for explaining a load acting on a first winch rope and a second winch rope connected to the bucket device. FIG. [Figure 6] 4 is a flowchart showing a calculation control operation performed by a controller provided in the crane. [Figure 7] 6 is a graph showing an example of a map that defines the relationship between the operation amount of a first winch operation lever and a target value of the rotation speed. [Figure 8] 6 is a graph showing an example of a map that defines the relationship between the operation amount of a first winch operating pedal and a target value of braking force. [Figure 9] 6 is a graph showing an example of a map that defines the relationship between the operation amount of a first winch operating pedal and a target value of braking force. [Figure 10] FIG. 2 is a block diagram showing an arithmetic control operation performed by the controller. [Figure 11] 4 is a flowchart showing a calculation control operation performed by the controller. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present disclosure will now be described with reference to the drawings.

[0022] 1 shows a crane 100, which is a construction machine according to the embodiment. The crane 100 includes a lower body 101, an upper rotating body 102 rotatably supported on the lower body 101, a hoisting member 104 supported on the upper rotating body 102 so as to be able to rise and fall, a first point sheave 105 and a second point sheave 106 attached to the tip of the hoisting member 104, a plurality of winches arranged on the lower body 101 or the upper rotating body 102, a bucket unit 10, and a bucket control device.

[0023] The lower body 101 is provided with a traveling device such as a crawler traveling device and is configured to be self-propelled. However, the lower body may be configured by a structure such as a support base that rotatably supports the upper slewing body 102 and cannot self-propel. The upper slewing body 102 includes a slewing frame 103 rotatably attached to the lower body 101, a cabin supported at the front of the slewing frame 103, and a counterweight supported at the rear of the slewing frame 103. The plurality of winches includes a first winch WC1, a second winch WC2, and a luffing winch WC3.

[0024] The luffing member 104 is configured by a boom rotatably supported by the slewing frame 103. However, the luffing member may include a boom and a jib rotatably supported at the tip of the boom. A gantry 107 is erected on the slewing frame 103. A lower spreader 110 is disposed at the upper end of the gantry 107. One end of a guy line 108 is connected to the tip of the luffing member 104, and the other end of the guy line 108 is connected to an upper spreader 109. The lower spreader 110 and the upper spreader 109 are spaced apart from each other. A luffing rope 111 is wound around the lower spreader 110 and the upper spreader 109. The luffing winch WC3 is disposed on the slewing frame 103 and has a winch drum DR3 around which the luffing rope 111 is wound. The luffing winch WC3 reduces or increases the separation distance between the upper spreader 109 and the lower spreader 110 by winding in or paying out the luffing rope 111. As the separation distance is reduced or increased, the luffing member 104 is luffed.

[0025] FIG. 2 is a block diagram showing the functional configuration of the bucket control device. FIG. 3 is a diagram showing the hydraulic circuit provided in the crane 100.

[0026] The first winch WC1 and the second winch WC2 are driven to open, close, and raise and lower the bucket apparatus 10. Specifically, as shown in FIGS. 1 to 3, the first winch WC1 has a first winch drum DR1 around which a first winch rope R1 is wound, a first winch motor 34 connected to the first winch drum DR1, a first clutch brake 40A, and a reducer 47. Similarly, the second winch WC2 has a second winch drum DR2 around which a second winch rope R2 is wound, a second winch motor 35 connected to the second winch drum DR2, a second clutch brake 40B, and a reducer 47. The first clutch brake 40A and the second clutch brake 40B constitute a clutch brake mechanism 40. The first winch rope R1 is an opening / closing rope for opening and closing the bucket apparatus 10, and the second winch rope R2 is a support rope for supporting the bucket apparatus 10. The first winch drum DR1 is an opening / closing drum that pays out and takes up the opening / closing rope, and the second winch drum DR2 is a support drum that pays out and takes up the support rope.

[0027] The first winch drum DR1 is supported by a support member (not shown) so as to be rotatable about a horizontal axis to enable the first winch rope R1 to be let out and reeled in. The second winch drum DR2 is supported by a support member (not shown) so as to be rotatable about a horizontal axis to enable the second winch rope R2 to be let out and reeled in.

[0028] The first point sheave 105 and the second point sheave 106 are arranged side by side on the left and right, and are attached to the tip of the hoisting member 104. The first winch rope R1 is wound around the first point sheave 105 and hangs down from the first point sheave 105. The second winch rope R2 is wound around the second point sheave 106 and hangs down from the second point sheave 106. The lower ends (tips) of the first and second winch ropes R1, R2 are connected to the bucket device 10.

[0029] The bucket device 10 is a working device called a so-called clam shell bucket. The right figure of FIG. 4 shows the open state in which the bucket device 10 is open, and the left figure of FIG. 4 shows the closed state in which the bucket device 10 is closed. The bucket device 10 includes an upper member 11, a lower member 16 disposed below the upper member 11, a pair of link members 12, 12, a pair of buckets 13, 13, a lower sheave 14, and an upper sheave 15.

[0030] The pair of link members 12, 12 are arranged at intervals in the horizontal direction. The upper ends of the pair of link members 12, 12 are respectively connected to the upper member 11 so as to be rotatable about a horizontal axis. One lower end of the pair of link members 12, 12 is connected to one of the pair of buckets 13, 13 so as to be rotatable about a horizontal axis, and the other lower end of the pair of link members 12, 12 is connected to the other of the pair of buckets 13, 13 so as to be rotatable about a horizontal axis.

[0031] The lower sheave 14 is supported by the lower member 16 so as to be rotatable about a horizontal axis. Each of the pair of buckets 13, 13 has a supported portion supported by the lower member 16 so as to be rotatable about a horizontal axis. The upper sheave 15 is supported by the upper member 11 so as to be rotatable about a horizontal axis.

[0032] The pair of buckets 13, 13 has an accommodation space capable of accommodating an object to be transported such as earth and sand. The pair of buckets 13, 13 can be displaced between a state where the lower ends of the buckets 13, 13 are adjacent to each other (the closed state) and a state where the lower ends of the buckets 13, 13 are separated in the horizontal direction (the open state) by rotating about the supported portion. The pair of link members 12, 12 rotate with respect to the upper member 11 as the buckets 13, 13 are displaced while supporting the buckets 13, 13. The pair of buckets 13, 13 can hold the object to be transported accommodated in the accommodation space by maintaining the closed state. The pair of buckets 13, 13 can discharge the object to be transported from the accommodation space to the outside of the buckets 13, 13 by switching from the closed state to the open state.

[0033] The first winch rope R1 is wound around the lower sheave 14 and the upper sheave 15, and the tip of the first winch rope R1 is fixed to either the upper member 11 or the lower member 16. The tip of the second winch rope R2 is fixed to the upper member 11.

[0034] The first and second winch motors 34, 35 are hydraulic motors and are connected to the hydraulic pump 31. The first winch motor 34 operates to rotate the first winch drum DR1 in either the forward or reverse direction, that is, either the payout direction or the winding direction, by receiving the supply of hydraulic oil discharged from the hydraulic pump 31. Similarly, the second winch motor 35 operates to rotate the second winch drum DR2 in either the forward or reverse direction, that is, either the payout direction or the winding direction, by receiving the supply of hydraulic oil discharged from the hydraulic pump 31. Thereby, the opening / closing and raising / lowering of the bucket device 10 by the cooperation of the first winch WC1 and the second winch WC2 are achieved. The hydraulic pump 31 is driven by a drive source such as an engine (not shown).

[0035] The speed reducer 47 of the first winch WC1 reduces the rotational speed of the first winch motor 34 and transmits the driving force (rotational force) from the first winch motor 34 to the first winch drum DR1. The speed reducer 47 of the second winch WC2 reduces the rotational speed of the second winch motor 35 and transmits the driving force (rotational force) from the second winch motor 35 to the second winch drum DR2. These speed reducers 47 each have, for example, a planetary gear mechanism.

[0036] The first clutch brake 40A can be switched between a connected state in which the driving force of the first winch motor 34 can be transmitted to the first winch drum DR1 and a free state in which the first winch rope R1 can be paid out from the first winch drum DR1 by the weight of the bucket device 10. The first clutch brake 40A can adjust the degree of connection between the first winch motor 34 and the first winch drum DR1 between the connected state and the free state.

[0037] Similarly, the second clutch brake 40B can be switched between a connected state in which the driving force of the second winch motor 35 can be transmitted to the second winch drum DR2 and a free state in which the second winch rope R2 can be paid out from the second winch drum DR2 by the weight of the bucket device 10. The second clutch brake 40B can adjust the degree of connection between the second winch motor 35 and the second winch drum DR2 between the connected state and the free state.

[0038] The connection state is a state in which the first and second winch ropes R1 and R2 can be paid out and wound up by the driving forces of the first and second winch motors 34 and 35. That is, when the first and second winch motors 34 and 35 are driven in the connection state, the driving forces of the first and second winch motors 34 and 35 are transmitted to the first and second winch drums DR1 and DR2 via the speed reducers 47 and 47, respectively. When the first and second winch drums DR1 and DR2 rotate, the first and second winch ropes R1 and R2 are paid out or wound up.

[0039] The free state is a state in which the first and second winch ropes R1 and R2 can be paid out from the first and second winch drums DR1 and DR2 by the tensions of the first and second winch ropes R1 and R2, that is, a state in which the bucket device 10 can freely fall. That is, the free state is a state in which the first and second winch ropes R1 and R2 can be paid out from the first and second winch drums DR1 and DR2 without rotating the first and second winch motors 34 and 35 in the pay-out direction for paying out the first and second winch ropes R1 and R2.

[0040] Further, the first clutch brake 40A can apply a first braking force to the first winch drum DR1, that is, can brake the first winch drum DR1. Similarly, the second clutch brake 40B can apply a second braking force to the second winch drum DR2, that is, can brake the second winch drum DR2.

[0041] When the first braking force against the rotation of the first winch drum DR1 becomes equal to or greater than a predetermined magnitude, a brake is applied to the first winch drum DR1, and it becomes impossible to pay out the first winch rope R1 from the first winch drum DR1. Similarly, when the second braking force against the rotation of the second winch drum DR2 becomes equal to or greater than a predetermined magnitude, a brake is applied to the second winch drum DR2, and it becomes impossible to pay out the second winch rope R2 from the second winch drum DR2. Therefore, the first braking force of the first clutch brake 40A and the second braking force of the second clutch brake 40B can maintain the state where the bucket device 10 is stationary without free-falling, and can also stop the freely falling bucket device 10.

[0042] In the present embodiment, each of the first clutch brake 40A and the second clutch brake 40B is a so-called wet brake, and includes a piston 42 driven by hydraulic pressure applied from a pilot hydraulic pressure source P, and a plurality of brake disks 41 (a plurality of clutch plates). Each of the plurality of brake disks 41 is, for example, a friction plate immersed in hydraulic oil.

[0043] The plurality of brake disks 41 can be switched between a state where the plurality of brake disks 41 are in contact with each other and a state where the plurality of brake disks 41 are separated from each other by the operation of the piston 42. Each of the first clutch brake 40A and the second clutch brake 40B is in the free state when the plurality of brake disks 41 are separated from each other, whereby the bucket device 10 can descend (free fall) by its own weight. Also, each of the first clutch brake 40A and the second clutch brake 40B enters the connected state when the plurality of brake disks 41 come into contact with each other.

[0044] More specifically, each of the first clutch brake 40A and the second clutch brake 40B includes a spring 46, and a pair of oil chambers 43 and 44 are formed in each of the first clutch brake 40A and the second clutch brake 40B. The piston 42 has a flange 45 that partitions the pair of oil chambers 43 and 44. When the hydraulic pressures applied from the pilot hydraulic pressure source P to the pair of oil chambers 43 and 44 are the same, the spring 46 biases the piston 42 so that the plurality of brake disks 41 are in contact with each other. When the hydraulic pressure applied from the pilot hydraulic pressure source P to one oil chamber 44 becomes larger than the hydraulic pressure applied to the other oil chamber 43 by a predetermined magnitude or more, the plurality of brake disks 41 are separated from each other.

[0045] The bucket control device is a device for opening, closing, raising, and lowering the bucket device 10 by controlling the driving of the first winch drum DR1 and the second winch drum DR2. This bucket control device includes a first control valve 32, a second control valve 33, a first payout proportional valve 61A, a first take-up proportional valve 61B, a second payout proportional valve 63A, a second take-up proportional valve 63B, a first brake proportional valve 62, a second brake proportional valve 64, a plurality of operating devices, and a controller 70. In the present embodiment, each of the proportional valves 61A, 61B, 62, 63A, 63B, and 64 is an electromagnetic proportional pressure reducing valve.

[0046] The first control valve 32 is interposed between the hydraulic pump 31 and the first winch motor 34, and the second control valve 33 is interposed between the hydraulic pump 31 and the second winch motor 35. Each of the first and second control valves 32 and 33 is constituted by a hydraulic pilot switching valve having a pair of pilot ports.

[0047] The pair of pilot ports are a pay-out pilot port and a take-up pilot port. Each of the first and second control valves 32, 33 is held in a neutral position to block the winch motor corresponding to the control valve (hereinafter referred to as the "corresponding winch motor") of the first and second winch motors 34, 35 from the hydraulic pump 31 when no pilot pressure is applied to both pilot ports. Each of the first and second control valves 32, 33 opens to form an oil passage for rotating the corresponding winch motor in the pay-out direction, that is, an oil passage for supplying hydraulic oil from the hydraulic pump 31 to the corresponding winch motor in the pay-out direction, when pilot pressure is applied to the pay-out pilot port. Each of the first and second control valves 32, 33 opens to form an oil passage for rotating the corresponding winch motor in the take-up direction, that is, an oil passage for supplying hydraulic oil from the hydraulic pump 31 to the corresponding winch motor in the take-up direction, when pilot pressure is applied to the take-up pilot port. The opening degree of each of the first and second control valves 32, 33 increases as the pilot pressure increases so as to allow hydraulic oil to flow at a flow rate corresponding to the pilot pressure input to the control valve.

[0048] The first pay-out proportional valve 61A is interposed between a pilot hydraulic source (not shown) and the pay-out pilot port of the first control valve 32, and opens to allow a pilot pressure proportional to the first pay-out command, which is an electric signal, to be input to the pay-out pilot port as the first pay-out command is input from the controller 70 to the proportional valve 61A. The first take-up proportional valve 61B is interposed between the pilot hydraulic source and the take-up pilot port of the first control valve 32, and opens to allow a pilot pressure proportional to the first take-up command, which is an electric signal, to be input to the take-up pilot port as the first take-up command is input from the controller 70 to the proportional valve 61B.

[0049] Similarly, the second payout proportional valve 63A is interposed between a pilot hydraulic source (not shown) and the payout pilot port of the second control valve 33, and opens to allow a pilot pressure proportional to the second payout command to be input to the payout pilot port as a second payout command, which is an electrical signal, is input to the proportional valve 63A from the controller 70. The second retraction proportional valve 63B is interposed between the pilot hydraulic source and the retraction pilot port of the second control valve 33, and opens to allow a pilot pressure proportional to the second retraction command to be input to the retraction pilot port as a second retraction command, which is an electrical signal, is input to the proportional valve 63B from the controller 70.

[0050] As described above, the first control valve 32, the first payout proportional valve 61A, and the first take-up proportional valve 61B constitute a first speed regulator that changes the flow rate and direction of hydraulic oil flowing into the first winch motor 34 in response to commands input to the proportional valves 61A and 61B. In other words, the first speed regulator changes the speed at which the first winch motor 34 rotates the first winch drum DR1. Similarly, the second control valve 33, the second payout proportional valve 63A, and the second take-up proportional valve 63B constitute a second speed regulator that changes the flow rate and direction of hydraulic oil flowing into the second winch motor 35 in response to commands input to the proportional valves 63A and 63B. In other words, the second speed regulator changes the speed at which the second winch motor 35 rotates the second winch drum DR2.

[0051] First brake proportional valve 62 is interposed between pilot hydraulic source P and first clutch brake 40A, and opens to allow hydraulic pressure (first pilot pressure) proportional to the first brake command, which is an electrical signal, to be input to oil chamber 43 of first clutch brake 40A as the first brake command is input to proportional valve 62 from controller 70. In this way, first brake proportional valve 62 can switch the state of first clutch brake 40A between the free state and the connected state.

[0052] Similarly, second brake proportional valve 64 is interposed between pilot hydraulic source P and second clutch brake 40B, and opens to allow hydraulic pressure (second pilot pressure) proportional to the second brake command to be input to oil chamber 43 of second clutch brake 40B as a second brake command, which is an electrical signal, is input to proportional valve 64 from controller 70. In this way, second brake proportional valve 64 can switch the state of second clutch brake 40B between the free state and the connected state.

[0053] The multiple operating devices include a first winch operating device 51, a second winch operating device 53, a first brake operating device 52, and a second brake operating device 54. The first winch operating device 51 has a first winch operating lever 51A and a first winch operating device main body 51B. The second winch operating device 53 has a second winch operating lever 53A and a second winch operating device main body 53B. The first brake operating device 52 has a first brake operating pedal 52A and a first brake operating device main body 52B. The second brake operating device 54 has a second brake operating pedal 54A and a second brake operating device main body 54B.

[0054] In the following description, the first winch drum DR1 may be referred to as the main winding drum, and the second winch drum DR2 may be referred to as the auxiliary winding drum. Also, the first winch operation lever 51A may be referred to as the main winding lever, and the second winch operation lever 53A may be referred to as the auxiliary winding lever. Further, the first brake operation pedal 52A may be referred to as the main winding pedal, and the second brake operation pedal 54A may be referred to as the auxiliary winding pedal. In the crane 100, instead of the bucket device 10, a main winding hook (not shown) may be attached to the tip of the first winch rope R1 (main winding rope), and an auxiliary winding hook (not shown) may be attached to the tip of the second winch rope R2 (auxiliary winding rope). "Main winding" is mainly used for heavy loads for lifting heavy loads, and "auxiliary winding" is mainly used for auxiliary use for lifting light loads.

[0055] The first winch operation lever 51A is an operation member to which a first rotation operation by an operator for specifying the driving speed (rotation speed) of the first winch drum DR1 is applied. Specifically, either a first payout operation for rotating the first winch drum DR1 in the payout direction so as to pay out the first winch rope R1 or a first winding operation for rotating the first winch drum DR1 in the winding direction so as to wind up the first winch rope R1 is applied as the first rotation operation to the first winch operation lever 51A.

[0056] The first winch operation device main body 51B inputs a command signal for commanding a rotation speed corresponding to the operation amount (lever operation amount) of the first rotation operation (first payout operation or first winding operation) applied to the first winch operation lever 51A to the controller 70.

[0057] Similarly, the second winch operation lever 53A is an operation member to which the operator applies a second rotation operation for specifying the drive speed (rotation speed) of the second winch drum DR2. Specifically, the second winch operation lever 53A is applied as the second rotation operation to rotate the second winch drum DR2 in the reeling direction so as to reel out the second winch rope R2, or to rotate the second winch drum DR2 in the reeling direction so as to reel in the second winch rope R2.

[0058] The second winch operating device main body 53B inputs a command signal to the controller 70 to command a rotational speed corresponding to the operation amount (lever operation amount) of the second rotation operation (second payout operation or second winding operation) applied to the second winch operating lever 53A.

[0059] The first brake operation pedal 52A is an operating member to which the operator applies a pedal operation (an example of a first brake operation) to specify a first braking force for the first winch drum DR1. The first brake operation device main body 52B inputs, to the controller 70, a command signal for commanding a braking force of a magnitude corresponding to the operation amount of the first pedal operation (pedal operation amount) applied to the first brake operation pedal 52A.

[0060] The second brake operation pedal 54A is an operating member to which the operator applies a pedal operation (an example of a second brake operation) to specify a second braking force for the second winch drum DR2. The second brake operation device main body 54B inputs, to the controller 70, a command signal for commanding a braking force of a magnitude corresponding to the amount of second pedal operation (pedal operation amount) applied to the second brake operation pedal 54A.

[0061] 2, the bucket control device further includes a first rotation sensor 81, a second rotation sensor 82, and a control mode setting unit. In this embodiment, the control mode setting unit includes an asynchronous control mode switch 90 (one-side open / close switch 90) and a bucket assist mode switch 91. The first rotation sensor 81 is an example of a first detector, and the second rotation sensor 82 is an example of a second detector.

[0062] The first rotation sensor 81 generates a first detection signal regarding a first rotation amount ωm, which is the rotation amount of the first winch drum DR1, and inputs the first detection signal to the controller 70. The second rotation sensor 82 generates a second detection signal regarding a second rotation amount ωa, which is the rotation amount of the second winch drum DR2, and inputs the second detection signal to the controller 70. Note that the first rotation sensor 81 may be a sensor that generates a detection signal regarding the rotation amount of the first point sheave 105 instead of the rotation amount of the first winch drum DR1, and the second rotation sensor 82 may be a sensor that generates a detection signal regarding the rotation amount of the second point sheave 106 instead of the rotation amount of the second winch drum DR2.

[0063] In this embodiment, the controller 70 sets the control mode by the controller 70 to one of a plurality of predetermined control modes based on a command signal input from the control mode setting unit. In this embodiment, the plurality of control modes include a bucket assist mode and a non-assist mode, and the bucket assist mode includes a synchronized control mode and a non-synchronized control mode. The plurality of control modes may further include other control modes.

[0064] The bucket assist mode is a control mode for the controller 70 to execute assist control to assist the operator so that the operator can cause the bucket device 10 to perform at least one of the opening / closing and lifting / lowering operations with simple operations. The non-assist mode is a control mode in which the above-described assist control is not executed. The assist control includes the main complementary synchronization control and the free synchronization control shown in FIG. 6, and the bucket stationary closing control, the excavation control, and the bucket stationary opening control shown in FIG. 11. These controls will be described later.

[0065] In the present embodiment, when the bucket assist mode switch 91 is in the on state, the control mode is set to the bucket assist mode, and when the bucket assist mode switch 91 is in the off state, the control mode is set to the non-assist mode. When the non-synchronization control mode switch 90 is in the on state in the bucket assist mode, the control mode is set to the non-synchronization control mode, and when the non-synchronization control mode switch 90 is in the off state in the bucket assist mode, the control mode is set to the synchronization control mode. Specifically, it is as follows.

[0066] The bucket assist mode switch 91 can set the control mode controlled by the controller 70 to bucket assist mode. When an operator turns on the bucket assist mode switch 91, the bucket assist mode switch 91 inputs an on command signal corresponding to the on operation to the controller 70, and the controller 70 sets the control mode to bucket assist mode. When the on operation is not performed on the bucket assist mode switch 91, the controller 70 does not set the control mode to bucket assist mode, but sets the control mode to another predetermined control mode (e.g., non-assist mode). The bucket assist mode switch 91 may be, for example, an input device provided on a monitor such as a touch panel located in the cabin, or may be an input device having a push button located in the cabin. The push button may be located on an operating member such as the first winch operation lever 51A.

[0067] The asynchronous control mode switch 90 can set the control mode controlled by the controller 70 to the asynchronous control mode. When the control mode is set to the bucket assist mode and an on operation for the asynchronous control mode is applied to the asynchronous control mode switch 90 by the operator, the asynchronous control mode switch 90 inputs an on command signal corresponding to the on operation to the controller 70, and the controller 70 sets the control mode to the asynchronous control mode. When the control mode is set to the bucket assist mode and the on operation is not applied to the asynchronous control mode switch 90, the controller 70 sets the control mode to the synchronous control mode. The asynchronous control mode switch 90 may be, for example, an input device having a push button located in the cabin, or may be an input device provided on a monitor such as a touch panel located in the cabin. The push button may be located on an operating member such as the first winch operation lever 51A.

[0068] In this embodiment, in the synchronization control mode, synchronization control such as main complementary synchronization control and free synchronization control, which will be described later, is performed. These main complementary synchronization control and free synchronization control will be described later.

[0069] Further, the control mode setting unit may include a plurality of schematic switches operated by an operator for more specifically specifying the operation of the bucket device 10 in the free synchronization control, and each of the plurality of switches may be configured to input a command signal corresponding to the operation to the controller 70. Examples of the operation of the bucket device 10 in the synchronization control mode include an "open and lower" operation in which the bucket device 10 is lowered in an open state and a "closed and lower" operation in which the bucket device 10 is lowered in a closed state.

[0070] In the free synchronization control in the synchronization control mode, the first and second braking forces in the first and second clutch brakes 40A and 40B are adjusted based on the operation amount (pedal operation amount) of the first pedal operation applied to the first brake operation pedal 52A.

[0071] The controller 70 is for controlling the driving of the first winch WC1 and the second winch WC2 to open / close and raise / lower the bucket device 10. As shown in FIG. 2, it has an open / close state determination unit 71, a braking force adjustment unit 72, and a drum operation control unit 73. The braking force adjustment unit 72, the first proportional valve 62 for braking, and the second proportional valve 64 for braking constitute a braking force adjustment mechanism.

[0072] The open / close state determination unit 71 determines the open / close state of the bucket device 10. That is, the open / close state determination unit 71 determines whether the bucket device 10 is in an open state or a closed state. The open / close state determination unit 71 in this embodiment determines the open / close state of the bucket device 10 based on the first rotation amount ωm and the second rotation amount ωa. Specifically, it is as follows.

[0073] First, the open / close state determination unit 71 estimates a first payout amount Lm, which is the payout amount of the first winch rope R1 paid out from the first winch drum DR1, based on the first rotation amount ωm, and estimates a second payout amount La, which is the payout amount of the second winch rope R2 paid out from the second winch drum DR2, based on the second rotation amount ωa. The first payout amount Lm is calculated, for example, using the following equation (1), and the second payout amount La is calculated, for example, using the following equation (2). Rm in equation (1) is the effective radius of the first winch drum DR1, and Ra in equation (2) is the effective radius of the second winch drum DR2.

[0074] Lm=Rm×ωm...Equation (1) La = Ra × ωa Equation (2) In the following description, the signs of the first and second payout amounts Lm, La when the bucket apparatus 10 is wound down (i.e., when the bucket apparatus 10 is lowered) are assumed to be positive, and the signs of the first and second payout amounts Lm, La when the bucket apparatus 10 is wound up (i.e., when the bucket apparatus 10 is raised) are assumed to be negative.

[0075] Next, the open / close state determination unit 71 calculates the relative difference (ΔL = Lm - La) between the first and second payout amounts Lm, La. For example, the state in which the bucket apparatus 10 is closed is set as the initial state, as shown in the left diagram of Fig. 4, and ΔL in this initial state is set to zero. When the bucket apparatus 10 is being wound up and down with the bucket apparatus 10 closed, the first and second payout amounts Lm, La each increase and decrease, but as long as the bucket apparatus 10 remains closed, the relationship "ΔL ≦ 0" is maintained.

[0076] On the other hand, when the bucket apparatus 10 is in an open state, the first extension amount Lm increases relatively to the second extension amount La. The open / closed state determination unit 71 can determine the opening degree of the bucket apparatus 10, for example, as follows.

[0077] Let L1 be the distance between the upper sheave 15 and the lower sheave 14 when the bucket device 10 is in a closed state (closed state) as shown in the left diagram of Fig. 4, let L2 be the distance between the upper sheave 15 and the lower sheave 14 when the bucket device 10 is in an open state (open state) as shown in the right diagram of Fig. 4, and let N be the number of turns (number of ropes) of the first winch rope R1 reeled around the upper sheave 15 and the lower sheave 14. In this case, the relative difference ΔL is expressed by the following equation (3).

[0078] ΔL=(L2-L1)×N (3) When the bucket device 10 is in a completely open state, that is, when the bucket device 10 is in a most open state, the distance between the upper sheave 15 and the lower sheave 14 is defined as L2max, and the relative difference between the first and second payout amounts Lm, La at this time is defined as ΔLmax. In this case, ΔLmax is expressed as in the following equation (4), and the opening degree of the bucket device 10 is expressed by the following equation (5).

[0079] ΔLmax=(L2max-L1)×N (4) Opening degree of the bucket device 10=ΔL / ΔLmax (5) Therefore, the open / closed state determining unit 71 can determine the open / closed state of the bucket apparatus 10 based on the opening degree of the bucket apparatus 10 calculated as described above.

[0080] The braking force adjustment unit 72 adjusts the first braking force and the second braking force. When the control mode is set to the synchronous control mode, a first brake operation to reduce the first braking force is applied to the first brake operating pedal 52A, and the opening / closing state determination unit 71 determines that the bucket apparatus 10 is in an open state, the braking force adjustment unit 72 performs the following opening / lowering control. The opening / lowering control is an example of free synchronous control. In this opening / lowering control, the first braking force and the second braking force are adjusted so that the bucket apparatus 10 descends by its own weight while maintaining the open state of the bucket apparatus 10. Furthermore, when the control mode is set to the synchronous control mode, a first brake operation to reduce the first braking force is applied to the first brake operating pedal 52A, and the opening / closing state determination unit 71 determines that the bucket apparatus 10 is in a closed state, the braking force adjustment unit 72 performs the following closing / lowering control. The closing / lowering control is an example of free synchronous control. In this closing-down control, the braking force adjustment unit 72 adjusts the first braking force and the second braking force so that the bucket apparatus 10 descends while maintaining the closed state of the bucket apparatus 10. The first braking operation that reduces the first braking force is, for example, an operation that reduces the pedal operation amount (depression amount) applied to the first brake operating pedal 52A.

[0081] The drum operation control unit 73 controls the operation of the first winch drum DR1 and the operation of the second winch drum DR2. In the main / auxiliary synchronization control in the synchronization control mode, the operation of the first winch drum DR1 and the operation of the second winch drum DR2 are controlled based on the first rotation operation applied to the first winch operation device 51.

[0082] Specifically, when the control mode is set to the synchronization control mode and a first payout operation is applied to the first winch operation lever 51A of the first winch operation device 51, the drum operation control unit 73 controls the operations of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 descends while maintaining the open / closed state of the bucket device 10. Further, when the control mode is set to the synchronization control mode and a first winding operation is applied to the first winch operation lever 51A of the first winch operation device 51, the drum operation control unit 73 controls the operations of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 ascends while maintaining the open / closed state of the bucket device 10. The open / closed state to be maintained is either the open state or the closed state.

[0083] FIG. 5 is a diagram for explaining the loads applied to the first winch rope R1 and the second winch rope R2 connected to the bucket device 10. The left diagram of FIG. 5 shows the first and second winch drums DR1, DR2, the first and second winch ropes R1, R2 wound around these winch drums DR1, DR2, and the bucket device 10 to which the tips of these winch ropes R1, R2 are connected. The right diagram of FIG. 5 is a schematic diagram for explaining the balance relationship of the forces in the left diagram of FIG. 5.

[0084] Let the tension of the first winch rope R1 be T1 (T opening / closing), and the tension of the second winch rope R2 be T2 (T support). Also, in the right diagram of FIG. 5, the case where the number of turns (number of rope passes) of the first winch rope R1 wound around the upper sheave 15 and the lower sheave 14 is 4 (the case of 4 ropes) is illustrated. From the right diagram of FIG. 5, the tension T1 is balanced with the sum of the acting forces (total of left and right) on the pair of left and right link members 12, 12 and three times T1 (T1×3) (Equation (6)).

[0085] T2 = T1×3 + acting force on the link (total of left and right) ···(6) Here, assuming that the weight of the bucket device 10 is supported approximately evenly by the link members 12, 12 and the lower sheave 14, the following equation (7) is established.

[0086] Force acting on the link (total of left and right) = T1 × 4 (7) Substituting equation (7) into equation (6), we obtain the relationship shown in the following equation (8).

[0087] T2=T1×3+T1×4=T1×7 (8) Therefore, when the relationship of the following formula (9) is satisfied, the bucket device 10 opens, and when the relationship of the following formula (10) is satisfied, the bucket device 10 closes.

[0088] T2>T1×7 (9) T2 <T1×7 ···(10) Note that the right-hand sides of formulas (9) and (10), "T1 x 7," are calculation examples for the case of four ropes being hung as described above, and if the number of ropes being hung changes, the right-hand sides can be changed accordingly. Also, if the shape of the bucket device 10 changes, the right-hand sides can be changed accordingly.

[0089] Further, the tension T1 of the first winch rope R1 and the tension T2 of the second winch rope R2, and the first braking force and the second braking force have the following relationship.

[0090] Tension T1 = First brake force (opening / closing side brake force) Tension T2 = Second brake force (support side brake force) From the above, when the bucket device 10 is opened and lowered, the first braking force and the second braking force are set as shown in the following formulas (11) and (12). The first set value and the second set value are preset values, and the second set value is set to, for example, a value seven times the first set value.

[0091] First brake force (open / close brake force) < First set value (11) Second brake force (support side brake force) > Second set value (12) Furthermore, during the closing and lowering operation of the bucket device 10, the first braking force and the second braking force are set as shown in the following formulas (13) and (14).

[0092] First brake force (open / close brake force) > First set value (13) Second brake force (support side brake force) < second set value (14) Next, the calculation and control operation performed by the controller 70 will be described with reference to the flowchart of FIG.

[0093] When the on command signal for specifying that the bucket assist mode is on is input from the bucket assist mode switch 91 (YES in step S10), the controller 70 sets the control mode to the bucket assist mode. When the on command signal for specifying that the asynchronous control mode is on is input from the asynchronous control mode switch 90 (YES in step S11), the controller 70 sets the control mode to the asynchronous control mode (step S12). The asynchronous control mode will be described later.

[0094] Furthermore, if the ON command signal for specifying that the bucket assist mode is ON is not input from the bucket assist mode switch 91 (NO in step S10), the controller 70 does not set the control mode to the bucket assist mode (step S19). In this case, the controller 70 may set the control mode to the non-assist mode in step S19.

[0095] If the ON command signal is not input from the non-synchronization control mode switch 90 in the bucket assist mode (NO in step S11), the controller 70 sets the control mode to the synchronization control mode and performs main and auxiliary synchronization control shown in steps S14 to S15, performs free synchronization control shown in steps S17 to S18, or performs neither main and auxiliary synchronization control nor free synchronization control (step S19).

[0096] When the bucket assist mode switch 91 is on (YES in step S10) and the asynchronous control mode switch 90 is off (NO in step S11), and when an operator's operation is applied to at least one of the first winch operation lever 51A and the first brake operation pedal 52A (YES in step S13 or YES in step S16), the controller 70 maintains the open / closed state of the bucket device 10 before the operation is input (that is, while maintaining the open / closed state of the bucket device 10 at the time when the operation is input), and controls the operations of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 is hoisted or lowered (steps S15, S18). When an operator's operation is applied to the first winch operation lever 51A and the first brake operation pedal 52A simultaneously, the operation applied to the first winch operation lever 51A takes precedence (YES in step S13).

[0097] Specifically, when a winding operation or a feeding operation is applied to the first winch operation lever 51A with the bucket device 10 in an open state or a closed state (YES in step S13), the controller 70 performs main complementary synchronization control to control the operations of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 is hoisted or lowered by the driving forces of the first winch motor 34 and the second winch motor 35 while maintaining the open or closed state of the bucket device 10 (steps S14, S15).

[0098] When the controller 70 is given an operation on the first brake operation pedal 52A without an operation being given to the first winch operation lever 51A while the bucket device 10 is in an open state or a closed state (NO in step S13, YES in step S16), the controller 70 performs free synchronization control to control the operations of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 descends due to its own weight while maintaining the open or closed state of the bucket device 10 (steps S17, S18).

[0099] The outline of the arithmetic control operation performed by the controller 70 is as described above. Hereinafter, the arithmetic control operation will be described in more detail.

[0100] [Master-Slave Synchronization Control] As shown in FIG. 6, when the controller 70 does not receive the on command signal from the non-synchronization control mode switch 90 in the bucket assist mode (NO in step S11), the controller 70 determines whether or not the first rotation operation has been given to the first winch operation lever 51A (step S13). When a command signal indicating that the first rotation operation has been given to the first winch operation lever 51A is input from the first winch operation device main body 51B to the controller 70 (YES in step S13), the controller 70 performs the following master-slave synchronization control (steps S14, S15).

[0101] In this master-slave synchronization control, the controller 70 controls the operations of the first winch drum DR1 and the second winch drum DR2 based on the first rotation operation given to the first winch operation lever 51A regardless of whether or not the second rotation operation has been given to the second winch operation lever 53A. In the master-slave synchronization control, the controller 70 controls the operations of the first winch drum DR1 (main winding drum) and the second winch drum DR2 (auxiliary winding drum) based on the first rotation operation so that they synchronize with each other. Thereby, the bucket device 10 can be wound up or down while maintaining the opening degree of the bucket device 10. Specifically, it is as follows.

[0102] In the master-slave synchronization control, first, the controller 70 sets target values for operating the first winch drum DR1 and the second winch drum DR2 (step S14). The target values may be, for example, target values related to the rotational speeds of the first and second winch drums DR1 and DR2, target values related to the master-slave payout amounts, or other target values other than these.

[0103] First, the case where the target values are target values related to the rotational speeds of the first and second winch drums DR1 and DR2 will be described. The controller 70 sets a target value of the rotational speed corresponding to the operation amount of the first rotation operation (the first payout operation or the first winding operation) given to the first winch operation lever 51A based on, for example, a preset map as shown in FIG. 7 and the command signal input from the first winch operation device main body 51B (step S14). The set target value is a target value common to both the first winch drum DR1 (main winding drum) and the second winch drum DR2 (auxiliary winding drum). Note that the setting of the target value does not have to be performed for each control cycle in the flowchart of FIG. 6, and may be performed in the first processing of step S14, and the target value set in the first processing may be maintained in the second and subsequent processes of step S14.

[0104] Next, the brake force adjustment unit 72 of the controller 70 inputs a command signal to the first proportional valve 62 for brakes so that the first clutch brake 40A is in the connected state, and inputs a command signal to the second proportional valve 64 for brakes so that the second clutch brake 40B is in the connected state. Specifically, for example, the brake force adjustment unit 72 adjusts the opening degrees of the first proportional valve 62 for brakes and the second proportional valve 64 for brakes so that the hydraulic pressures applied from the pilot hydraulic pressure source P to the pair of oil chambers 43 and 44 in the first clutch brake 40A are the same, and the hydraulic pressures applied from the pilot hydraulic pressure source P to the pair of oil chambers 43 and 44 in the second clutch brake 40B are the same. As a result, the first clutch brake 40A becomes the connected state in which the driving force of the first winch motor 34 can be transmitted to the first winch drum DR1, and the second clutch brake 40B becomes the connected state in which the driving force of the second winch motor 35 can be transmitted to the second winch drum DR2.

[0105] Next, the drum operation control unit 73 of the controller 70 inputs a command to the first proportional valve 61A for payout or the first proportional valve 61B for winding so that the first winch drum DR1 (main winding drum) and the second winch drum DR2 (auxiliary winding drum) rotate at a set target value (rotation speed) in a direction corresponding to the direction of the first rotation operation (payout direction or winding direction), and inputs a command to the second proportional valve 63A for payout or the second proportional valve 63B for winding (step S15). As a result, the opening degrees of the first proportional valve 61A for payout or the first proportional valve 61B for winding and the opening degrees of the second proportional valve 63A for payout or the second proportional valve 63B for winding are adjusted, and the bucket device 10 is hoisted or lowered by the driving forces of the first winch motor 34 and the second winch motor 35 while maintaining the open state or the closed state of the bucket device 10.

[0106] Next, a case where the target value is a target value related to the main and auxiliary payout amounts will be described. Based on the first detection signal input from the first rotation sensor 81 and the second detection signal input from the second rotation sensor 82, the controller 70 calculates the first payout amount Lm and the second payout amount La in the above-described procedure. Then, the controller 70 calculates the main-auxiliary payout amount relative difference ΔL, which is the relative difference between the calculated first payout amount Lm and the second payout amount La, and sets the calculated main-auxiliary payout amount relative difference ΔL as the target value ΔL1 (control target value) (step S14). This setting of the target value does not have to be performed for each control cycle in the flowchart of FIG. 6, and is performed in the first processing of step S14. In the processing after the second time of step S14, the target value set in the first processing is maintained.

[0107] When the first rotation operation applied to the first winch operation lever 51A is the first payout operation, the controller 70 inputs commands corresponding to the lever operation amount of the first payout operation to the proportional valve 61A and the proportional valve 63A. When the first rotation operation applied to the first winch operation lever 51A is the first winding operation, the controller 70 inputs commands corresponding to the lever operation amount of the first winding operation to the proportional valve 61B and the proportional valve 63B. Thereby, the first winch drum DR1 (main winding drum) and the second winch drum DR2 (auxiliary winding drum) rotate in the same rotation direction at substantially the same rotation speed.

[0108] Even if the same commands are given to the proportional valve 61A and the proportional valve 63A, or the same commands are given to the proportional valve 61B and the proportional valve 63B as described above, a difference may occur between the rotational speed of the first winch drum DR1 and the rotational speed of the second winch drum DR2 due to variations that can occur in the hydraulic circuit. When such a difference in rotational speed occurs, the main auxiliary payout amount relative difference ΔL changes with respect to the target value ΔL1. The controller 70 calculates the deviation (ΔL1 - ΔL) between the main auxiliary payout amount relative difference ΔL (current value ΔL) at that time and the above target value ΔL1, corrects the command for the proportional valve so that the deviation approaches zero, and performs feedback control (for example, PID control) to output the corrected command to the proportional valves 61A, 63A or the proportional valves 61B, 63B. Thereby, in the main auxiliary synchronization control, the hoisting or lowering of the bucket device 10 is performed while the opening degree of the bucket device 10 is maintained with higher accuracy.

[0109] [Free synchronization control] As shown in FIG. 6, when the on command signal is not input from the non-synchronization control mode switch 90 (NO in step S11) and the first rotation operation is not given to the first winch operation lever 51A (NO in step S13), the controller 70 determines whether or not a first pedal operation (main winding pedal operation) is given to the first brake operation pedal 52A (step S16). Specifically, in step S16, the controller 70 determines whether or not a first brake operation for reducing the first braking force is given to the first brake operation pedal 52A. When a command signal indicating that a first brake operation for reducing the first braking force is given to the first brake operation pedal 52A is input from the first brake operation device main body 52B (YES in step S16), the controller 70 performs the following free synchronization control (steps S17, S18).

[0110] In this free synchronization control, regardless of whether a second pedal operation (auxiliary winding pedal operation) is applied to the second brake operation pedal 54A, the first braking force for the first winch drum DR1 and the second braking force for the second winch drum DR2 are controlled based on the first pedal operation (main winding pedal operation) applied to the first brake operation pedal 52A. Thereby, in the free synchronization control, an appropriate opening-down operation and an appropriate closing-down operation of the bucket device 10 are performed. In this free synchronization control, each of the first and second control valves 32, 33 has no pilot pressure applied to both pilot ports and is held in the neutral position. Therefore, the first and second winch motors 34, 35 are not driven. In the free synchronization control, the controller 70 controls the proportional valves 62, 64 based on the first pedal operation applied to the first brake operation pedal 52A, thereby controlling the first braking force and the second braking force. Hereinafter, the free synchronization control will be specifically described.

[0111] In the free synchronization control, first, the controller 70 determines the open / closed state of the bucket device 10 (step S17). This determination process is automatically executed when it is determined in the process of step S16 that the first pedal operation is applied to the first brake operation pedal 52A.

[0112] Specifically, the opening / closing state determination unit 71 of the controller 70 calculates the opening degree (ΔL / ΔLmax) of the bucket device 10 in the above-described procedure based on the first and second detection signals input from the first and second rotation sensors 81 and 82. When the calculated opening degree is zero, the opening / closing state determination unit 71 determines that the bucket device 10 is in the closed state (step S17). Further, the opening / closing state determination unit 71 may determine that the bucket device 10 is in the closed state when the calculated opening degree is equal to or less than a closed state determination threshold value that is a preset threshold value. Further, when an opening / closing state input switch, which is a switch through which an operator can input the opening / closing state of the bucket device 10, is provided in the cabin, the opening / closing state determination unit 71 may determine whether the bucket device 10 is in the open state or the closed state based on the information input by the operator through the opening / closing state input switch.

[0113] Note that the determination of the opening / closing state (determination of the opening degree) of the bucket device 10 does not necessarily need to be performed for each control cycle of step S17 in the flowchart of FIG. 6, and may be performed in the first processing of step S17, and the determination result determined in the first processing may be maintained in the second and subsequent processes of step S17.

[0114] FIG. 8 is a graph showing an example of a map in which the relationship between the operation amount (horizontal axis) applied to the first brake operation pedal 52A (main winding pedal) and the target values of the first braking force and the second braking force (vertical axis) is defined in advance during the lowering operation of the bucket device 10.

[0115] When the opening / closing state determination unit 71 determines that the bucket apparatus 10 is in the open state (step S17), the braking force adjustment unit 72 of the controller 70 sets the target value of the first braking force and the target value of the second braking force based on the map shown in Fig. 8 and the command signal input from the first brake operating device main body 52B. In the map shown in Fig. 8 used during the operation of opening and lowering the bucket apparatus 10, the target value of the first braking force and the target value of the second braking force are set to values that satisfy the following equations (15) and (16), regardless of the amount of operation applied to the first brake operating pedal 52A (main hoist pedal).

[0116] Target value of first brake force (opening / closing side brake force) < first set value (15) Target value of second brake force (support side brake force) > second set value (16) Next, the braking force adjustment unit 72 of the controller 70 inputs a command signal corresponding to the target value of the first braking force to the first brake proportional valve 62, and inputs a command signal corresponding to the target value of the second braking force to the second brake proportional valve 64. That is, in the opening / lowering control, the braking force adjustment unit 72 imposes a lower limit on the second braking force (support-side braking force), and issues commands to the first brake proportional valve 62 and the second brake proportional valve 64 so that the second braking force is higher than the first braking force by at least a preset ratio (seven times in the above specific example). As a result, the first braking force and the second braking force can be made to approach their target values simply by operating the first brake operating pedal 52A, and the opening / lowering operation of lowering the bucket unit 10 while maintaining the bucket unit 10 in an open state can be appropriately performed.

[0117] As shown in Fig. 8, as the amount of operation applied to the first brake operating pedal 52A (main hoist pedal) decreases, the target value also decreases, and accordingly the first braking force and the second braking force gradually decrease. When the amount of operation of the first brake operating pedal 52A reaches a certain amount of operation indicated as "bucket starts moving" on the horizontal axis of Fig. 8, the bucket device 10 starts to descend.

[0118] FIG. 9 is a graph showing an example of a map that prescribes in advance the relationship between the amount of operation (horizontal axis) applied to the first brake operation pedal 52A (main winding pedal) and the target values of the first braking force and the second braking force during the closing operation of the bucket device 10.

[0119] When the opening / closing state determination unit 71 determines that the bucket device 10 is in the closed state (step S17), the brake force adjustment unit 72 of the controller 70 sets the target value of the first braking force and the target value of the second braking force based on the map shown in FIG. 9 and the command signal input from the first brake operation device main body 52B, respectively. In the map shown in FIG. 9 used during the closing operation of the bucket device 10, regardless of the amount of operation applied to the first brake operation pedal 52A (main winding pedal), the target value of the first braking force and the target value of the second braking force are set to values that satisfy the following formulas (17) and (18).

[0120] Target value of the first braking force (opening / closing side braking force) > first set value ···(17) Target value of the second braking force (support side braking force) < second set value ···(18) Next, the brake force adjustment unit 72 of the controller 70 inputs a command signal corresponding to the target value of the first braking force to the first brake proportional valve 62 and inputs a command signal corresponding to the target value of the second braking force to the second brake proportional valve 64. Thereby, each of the first braking force and the second braking force can be brought closer to the target value only by operating the first brake operation pedal 52A, and the closing operation of lowering the bucket device 10 while maintaining the closed state of the bucket device 10 is appropriately performed. Note that in the closing control, the brake force adjustment unit 72 releases the lower limit restriction of the second braking force (support side braking force) in the opening control.

[0121] In the specific example shown in Fig. 9, the first braking force indicated by the solid line and the second braking force indicated by the solid line are set to approximately the same value, but for example, the target value of the second braking force (support-side braking force) may be set so that there is a large difference between it and the target value of the first braking force, as indicated by the dashed line in Fig. 9. Even in this case, as long as the relationships of the above formulas (17) and (18) are satisfied, the closing-down operation of lowering the bucket assembly 10 while maintaining the closed state of the bucket assembly 10 is performed appropriately.

[0122] The braking force adjustment unit 72 of the controller 70 may calculate the command values for the first and second brake proportional valves 62, 64, for example, as follows: The following relationship exists between the braking forces shown in Figures 8 and 9 and the braking torques generated in the first and second clutch brakes 40A, 40B.

[0123] Braking force = effective drum radius x brake torque 8 and 9 and the above-mentioned relational expression, braking force adjuster 72 may determine the control target value of the braking torque. In addition, since a nearly proportional relationship generally holds between the current value input to proportional valves 62, 64 and the braking torque, braking force adjuster 72 can determine and control the command value to the proportional valve based on this proportional relationship (or may use a map of the relationship between the two).

[0124] It is preferable that the braking force adjuster 72 of the controller 70 performs the free tuning control of step S18 in the flowchart of Fig. 6 using feedback control as shown in Fig. 10. Specifically, this is as follows.

[0125] As shown in FIG. 10, the braking force adjustment unit 72 calculates the main winding free proportional valve target value (feed forward, hereinafter referred to as "FF"), which is the target value of the command input to the first braking proportional valve 62, and the auxiliary winding free proportional valve target value (FF), which is the target value of the command input to the second braking proportional valve 64, based on the determination result of the opening / closing state of the bucket device 10, the operation amount of the first pedal operation applied to the first braking operation pedal 52A, and the map shown in FIG. 8 or FIG. 9.

[0126] The braking force adjustment unit 72 sets the target value of the opening degree of the bucket device 10 or the target value ΔL2 of the value corresponding to the opening degree based on the opening / closing state of the bucket device 10 determined by the opening / closing state determination unit 71. Specifically, in the present embodiment, the braking force adjustment unit 72 calculates the main auxiliary payout amount relative difference target value ΔL2, which is the target value of the main auxiliary payout amount relative difference, based on the detection signals input from the first and second rotation sensors 81 and 82. The main auxiliary payout amount relative difference target value ΔL2 is an example of the target value of the value corresponding to the opening degree of the bucket device 10. The braking force adjustment unit 72 sets the difference (Lm - La) between the first payout amount Lm and the second payout amount La of the first winch rope R1 estimated (calculated for the first time) after the start of this free synchronization control as the main auxiliary payout amount relative difference target value ΔL2. Hereinafter, the main auxiliary payout amount relative difference target value ΔL2 may be simply referred to as the relative difference target value ΔL2.

[0127] The braking force adjustment unit 72 calculates the first payout amount Lm of the first winch rope R1 and the second payout amount La of the second winch rope R2 based on the detection signals input from the first and second rotation sensors 81 and 82, and calculates the actual relative difference ΔL (ΔL = Lm - La), which is the relative difference between these.

[0128] The braking force adjustment unit 72 calculates the deviation (ΔL2 - ΔL) between the relative difference target value ΔL2 and the actual relative difference ΔL, and applies feedback control (for example, PID control) based on this deviation (ΔL2 - ΔL) to calculate the main winding free proportional valve target value (feedback, hereinafter referred to as "FB") and the auxiliary winding free proportional valve target value (FB).

[0129] The braking force adjustment unit 72 can calculate the main winding free proportional valve target value (FB) and the auxiliary winding free proportional valve target value (FB) respectively by using the deviation (ΔL2 - ΔL) and, for example, the following formulas (19) and (20).

[0130] Main winding free proportional valve target value (FB) = proportional gain × deviation + integral gain × deviation integral value + derivative gain × deviation derivative value ··· (19) Auxiliary winding free proportional valve target value (FB) = -(proportional gain × deviation + integral gain × deviation integral value + derivative gain × deviation derivative value) ··· (20) The braking force adjustment unit 72 calculates the main winding free proportional valve target value (final) by adding the main winding free proportional valve target value (FB) to the main winding free proportional valve target value (FF), and calculates the auxiliary winding free proportional valve target value (final) by adding the auxiliary winding free proportional valve target value (FB) to the auxiliary winding free proportional valve target value (FF). The braking force adjustment unit 72 inputs the calculated main winding free proportional valve target value (final) to the first braking proportional valve 62, and inputs the calculated auxiliary winding free proportional valve target value (final) to the second braking proportional valve 64. Note that the "main - auxiliary free device" shown in FIG. 10 includes the proportional valves 62 and 64.

[0131] When the deviation (ΔL2 - ΔL) is, for example, a positive value, the difference between the first payout amount (the payout amount of the main winding) and the second payout amount (the payout amount of the auxiliary winding) is smaller than that in the initial posture which is the posture at the time when the free synchronization control is started. This means that the posture of the bucket device 10 is displaced in the closing direction (becoming self-closing) compared to the initial posture. In this case, it is necessary to increase the first payout amount by weakening the first braking force (the braking force of the main winding) or decrease the second payout amount by strengthening the second braking force (the braking force of the auxiliary winding) to increase the actual relative difference ΔL and make it closer to the relative difference target value ΔL2. As a method for this, for example, in P control, a proportional gain is multiplied by ΔL to calculate a correction amount of the proportional valve target value by P control, and this correction amount is given as an addition value to the proportional valve target value of the auxiliary winding or as a subtraction value to the proportional valve target value of the main winding, thereby performing the above-described correction control. The proportional gain may be different values for each calculation of the correction value of the main winding and each calculation of the correction value of the auxiliary winding. Also, an integral value of the deviation may be calculated and integral control may be performed by multiplying this by an integral gain. Further, a differential of the deviation may be calculated and differential control may be performed by multiplying this by a differential gain.

[0132] [Non-synchronization control mode] Next, the non-synchronization control mode will be described. As described above, when the controller 70 receives the on command signal for designating the activation of the non-synchronization control mode from the non-synchronization control mode switch 90 (YES in step S11), the control mode is set to the non-synchronization control mode (step S12).

[0133] FIG. 11 is a flowchart showing the arithmetic control operation related to the asynchronous control mode performed by the controller 70. When the bucket assist mode switch 91 is in the ON state and the asynchronous control mode switch 90 is in the ON state, if a winding operation is applied to the first winch operation lever 51A (YES in step S31), and the state where the first brake operation pedal 52A is depressed is maintained (YES in step S32), the controller 70 performs bucket stationary closing control to operate the bucket device 10 in the closing direction while maintaining the height of the bucket device 10. In this bucket stationary closing control, the brake force adjustment unit 72 controls the proportional valve 64 so that the second brake force on the bucket support side is increased to apply the brake, and the drum operation control unit 73 controls the proportional valve 61B so that the first winch drum DR1 on the bucket opening / closing side rotates in the winding direction according to the operation amount of the winding operation applied to the first winch operation lever 51A.

[0134] Note that the state where the first brake operation pedal 52A is depressed and maintained means the case where the first brake operation pedal 52A is depressed and the first brake operation pedal 52A is not operated to reduce the first brake force.

[0135] Also, when the bucket assist mode switch 91 is on and the non-synchronous control mode switch 90 is on, if a winding operation is applied to the first winch operation lever 51A (YES in step S31), and the first brake operation pedal 52A is operated so as to reduce (weaken) the first braking force (NO in step S32), the controller 70 operates the bucket device 10 in the closing direction, and performs excavation control to reduce the second braking force (the tension of the second winch rope R2) in accordance with the decrease in the operation amount of the first brake operation pedal 52A (step S34). In this excavation control, when excavating soil with the bucket device 10, the bucket device 10 can be operated so as to sink downward while excavating. This control enables more soil to be scooped compared to the above-described bucket stationary closing control in which the bucket device 10 is closed without changing the height of the bucket device 10. In this excavation control, the brake force adjustment unit 72 controls the proportional valve 64 so that the second braking force on the bucket support side decreases in accordance with the decrease in the operation amount of the first brake operation pedal 52A, and the drum operation control unit 73 controls the proportional valve 61B so that the first winch drum DR1 on the bucket opening / closing side rotates in the winding direction in accordance with the operation amount of the winding operation applied to the first winch operation lever 51A.

[0136] Furthermore, when the bucket assist mode switch 91 is on and the asynchronous control mode switch 90 is on, if neither a winding operation nor a paying-out operation is applied to the first winch operation lever 51A and the first winch operation lever 51A is in the neutral position (NO in step S31), and if the first brake operation pedal 52A is operated to reduce (weaken) the first brake force (YES in step S35), the controller 70 performs bucket static opening control such that the bucket apparatus 10 opens while maintaining the height of the bucket apparatus 10. In this bucket static opening control, the bucket apparatus 10 is supported by the second winch rope R2 (auxiliary hoisting rope), while the first winch rope R1 is set free and the tension of the first winch rope R1 is reduced, thereby executing an operation to open the bucket apparatus 10 in the air. In this bucket stationary opening control, the braking force adjustment unit 72 controls the first brake proportional valve 62 and the second brake proportional valve 64 so that, while the second braking force on the bucket support side is increased and the brake is applied, the first braking force on the bucket opening / closing side changes in accordance with the pedal operation amount of the first brake operating pedal.

[0137] The present disclosure is not limited to the above-described embodiments. The present disclosure includes, for example, the following embodiments.

[0138] (A) Crane specifications The crane according to the embodiment shown in Fig. 1 does not have a jib or struts, but the specifications of the crane are not limited to those shown in Fig. 1. The crane according to the present disclosure may be a luffing crane equipped with a jib, front struts, and rear struts, or may be a fixed jib crane equipped with a jib and one strut. The crane according to the present disclosure may also be a crane equipped with a mast instead of a gantry (for example, a large crane).

[0139] (B) Winch rope and winch drum In the above-described embodiment, the first winch rope R1 is the opening / closing rope, the second winch rope R2 is the support rope, the first winch drum DR1 is the opening / closing drum, and the second winch drum DR2 is the support drum. However, these may have the reverse configuration. That is, the first winch rope R1 may be the support rope, the second winch rope R2 may be the opening / closing rope, the first winch drum DR1 may be the support drum, and the second winch drum may be the opening / closing drum.

[0140] (C) The opening / closing state determination unit may be configured to determine the opening / closing state of the bucket device 10 based on the relative position between the lower ends of the pair of buckets 13, 13. In this case, the bucket control device includes a detection sensor that detects the relative position between the lower ends of the pair of buckets 13, 13. The detection sensor may be, for example, a sensor that detects whether or not the lower ends of the pair of buckets 13, 13 are in contact with each other, or a sensor that detects the distance between the lower ends of the pair of buckets 13, 13.

[0141] (D) Regarding the target value of the opening degree In the above-described embodiment, the main supplementary payout amount relative difference target value ΔL2 is used as the target value of the value corresponding to the opening degree of the bucket device 10. However, the opening degree of the bucket device 10 may be used as the target value.

[0142] (E) Regarding the operating device The operating device according to the present disclosure may be appropriately selected according to the types of the first and second winches and their driving devices. For example, each of the operating device bodies 51B, 53B, 52B, and 54B of the first winch operating device 51, the second winch operating device 53, the first brake operating device 52, and the second brake operating device 54 shown in FIGS. 2 and 3 may be replaced with a remote control valve that outputs a pilot pressure according to an operation. In this case, proportional valves 61A and 61B are respectively interposed between the remote control valve of the first winch operating device 51 and a pair of pilot ports of the first control valve, and proportional valves 63A and 63B are respectively interposed between the remote control valve of the second winch operating device 53 and a pair of pilot ports of the second control valve 33. Further, a proportional valve 62 is interposed between the remote control valve of the first brake operating device 52 and the first clutch brake 40A, and a proportional valve 64 is interposed between the remote control valve of the second brake operating device 54 and the second clutch brake 40B.

[0143] (F) Regarding winches The first and second winches according to the present disclosure may be, for example, electric winches. In this case, the hydraulic circuit shown in FIG. 3 can be replaced with an electric circuit (for example, a circuit including an inverter) that drives the electric winch.

Description of reference numerals

[0144] 10: Bucket device 34: First winch motor 35: Second winch motor 40: Clutch brake mechanism 40A: First clutch brake 40B: Second clutch brake 51: First winch operating device 52: First brake operating device 53: Second winch operating device 54: Second brake operating device 61A: First proportional valve for payout 61B: First proportional valve for winding 62: Proportional valve for the first brake 63A: Proportional valve for the second payout 63B: Proportional valve for the second take-up 64: Proportional valve for the second brake 70: Controller 71: Opening / closing state determination unit 72: Brake force adjustment unit 73: Drum operation control unit 90: Non-synchronous control mode switch (single-sided opening / closing switch) 91: Bucket assist mode switch 100: Crane DR1: First winch drum (an example of an opening / closing drum) DR2: Second winch drum (an example of a support drum) La: Second payout amount Lm: First payout amount R1: First winch rope (an example of an opening / closing rope) R2: Second winch rope (an example of a support rope) ΔL2: Target value

Claims

1. A first winch drum that pays out and winds up a first winch rope, A second winch drum that pays out and winds up a second winch rope, A bucket device to which the first winch rope and the second winch rope are connected and which can be opened and closed and raised and lowered in response to the rotation of the first winch drum and the rotation of the second winch drum. A bucket control device in a construction machine, comprising: A clutch brake mechanism that can put the first winch rope and the second winch rope in a free state in which they can be paid out from the first winch drum and the second winch drum according to the weight of the bucket device, and can apply a first braking force and a second braking force to the first winch drum and the second winch drum respectively. A clutch brake mechanism, A first brake operating device to which a first brake operation for adjusting the first braking force is applied, A second brake operating device to which a second brake operation for adjusting the second braking force is applied, A control mode setting unit that can set the control mode to a synchronization control mode in which the first braking force and the second braking force can be adjusted based on the first brake operation, An opening / closing state determination unit that determines whether or not the bucket device is in an open state, When the control mode is set to the synchronization control mode, a first brake operation for reducing the first braking force is applied to the first brake operating device, and the opening / closing state determination unit determines that the bucket device is in the open state, the opening lowering control for adjusting the first braking force and the second braking force so that the bucket device descends under its own weight while maintaining the open state of the bucket device. A brake force adjustment mechanism that performs control,

2. A bucket control device in a construction machine according to Claim 1, The opening / closing state determination unit can further determine whether or not the bucket device is in a closed state, The brake force adjustment mechanism performs closing and lowering control, which is control for adjusting the first brake force and the second brake force so that the bucket device descends due to its own weight while maintaining the closed state of the bucket device when the control mode is set to the synchronization control mode, the first brake operation for reducing the first brake force is applied to the first brake operation device, and the opening / closing state determination unit determines that the bucket device is in the closed state. A bucket control device for a construction machine.

3. A bucket control device for a construction machine according to claim 1 or 2, wherein the first winch rope is an opening / closing rope for opening and closing the bucket device, and the second winch rope is a support rope for supporting the bucket device, the first winch drum is an opening / closing drum for feeding out and winding up the opening / closing rope, and the second winch drum is a support drum for feeding out and winding up the support rope, the clutch brake mechanism includes a first clutch brake capable of applying the first brake force to the first winch drum, and a second clutch brake capable of applying the second brake force to the second winch drum. The brake force adjustment mechanism includes a first proportional valve for a brake that outputs a first pilot pressure for adjusting the first brake force to the first clutch brake, and a second proportional valve for a brake that outputs a second pilot pressure for adjusting the second brake force to the second clutch brake. In the opening and lowering control, the brake force adjustment mechanism includes a brake force adjustment unit that gives commands to the first proportional valve for a brake and the second proportional valve for a brake so that the second brake force becomes higher than the first brake force by a preset ratio or more. A bucket control device for a construction machine.

4. A bucket control device for a construction machine according to any one of claims 1 to 3, further comprising a first detector for detecting a first payout amount that is the payout amount of the first winch rope, and a second detector for detecting a second payout amount that is the payout amount of the second winch rope. The bucket control device in a construction machine, wherein the opening / closing state determination unit determines the opening / closing state of the bucket device based on the difference between the first payout amount and the second payout amount.

5. A bucket control device in a construction machine according to claim 4, wherein, in the lowering control, the brake force adjustment mechanism sets a target value of the opening degree of the bucket device or a target value of a value corresponding to the opening degree based on the opening / closing state of the bucket device determined by the opening / closing state determination unit, calculates a deviation between the actual opening degree of the bucket device or a value corresponding thereto and the target value, and performs control to reduce the deviation by feeding back the deviation. A bucket control device in a construction machine.

6. A bucket control device in a construction machine according to any one of claims 1 to 5, a first winch operation device provided with a first payout operation for rotating the first winch drum so as to payout the first winch rope and a first winding operation for rotating the first winch drum so as to wind up the first winch rope; a second winch operation device provided with a second payout operation for rotating the second winch drum so as to payout the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope; and a drum operation control unit, wherein the clutch brake mechanism is configured to be able to switch between the free state and a connected state in which a driving force for driving the first winch drum and the second winch drum can be transmitted to the first winch drum and the second winch drum, and in the synchronization control mode, when the clutch brake mechanism is in the connected state, it is possible to control the operation of the first winch drum and the operation of the second winch drum based on one of the first payout operation and the first winding operation, the drum operation control unit When the control mode is set to the synchronization control mode and the first payout operation is applied to the first winch operating device, the operation of the first winch drum and the operation of the second winch drum are controlled so that the bucket device descends while the open / closed state of the bucket device is maintained. A bucket control device for a construction machine that controls the operation of the first winch drum and the operation of the second winch drum so that the bucket device ascends while maintaining the open / closed state of the bucket device when the control mode is set to the synchronization control mode and the first winding operation is applied to the first winch operating device.

7. A bucket control device for a construction machine according to any one of claims 1 to 5, A first winch operating device to which a first payout operation for rotating the first winch drum to payout the first winch rope and a first winding operation for rotating the first winch drum to wind up the first winch rope are applied, A second winch operating device to which a second payout operation for rotating the second winch drum to payout the second winch rope and a second winding operation for rotating the second winch drum to wind up the second winch rope are applied, further comprising: The control mode setting unit is configured to be able to set the control mode to any one of a plurality of modes including the synchronization control mode and the non-synchronization control mode. A bucket control device for a construction machine that performs bucket stationary closing control, which is control to operate the bucket device in a closing direction while maintaining the height of the bucket device when the control mode is set to the non-synchronization control mode and the first winding operation is applied to the first winch operating device.

8. A bucket control device for a construction machine according to any one of claims 1 to 5, A first winch operating device to which a first payout operation for rotating the first winch drum to payout the first winch rope and a first winding operation for rotating the first winch drum to wind up the first winch rope are applied, A second winch operating device provided with a second payout operation for rotating the second winch drum so as to pay out the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope, The control mode setting unit is configured to be able to set the control mode to any one of a plurality of modes including the synchronous control mode and the asynchronous control mode, The bucket control device for a construction machine, wherein the braking force adjustment mechanism performs excavation control which is control to operate the bucket device in a closing direction and reduce a second braking force in response to a decrease in an operation amount with respect to the first braking operation device when the control mode is set to the asynchronous control mode, a first winding operation is given to the first winch operating device, and the first braking operation device is operated to reduce the first braking force.

9. A bucket control device for a construction machine according to any one of claims 1 to 5, A first winch operating device provided with a first payout operation for rotating the first winch drum so as to pay out the first winch rope and a first winding operation for rotating the first winch drum so as to wind up the first winch rope, A second winch operating device provided with a second payout operation for rotating the second winch drum so as to pay out the second winch rope and a second winding operation for rotating the second winch drum so as to wind up the second winch rope, The control mode setting unit is configured to be able to set the control mode to any one of a plurality of modes including the synchronous control mode and the asynchronous control mode, The bucket control device for a construction machine, wherein the braking force adjustment mechanism performs bucket stationary opening control which is control to operate the bucket device in an opening direction while maintaining the height of the bucket device when the control mode is set to the asynchronous control mode, neither the first payout operation nor the first winding operation is given to the first winch operating device, and the first braking operation device is operated to reduce the first braking force.

Images