Bucket control device, construction machine, and bucket control method

Abstract

The present invention provides a bucket control device that can suppress malfunctions such as turbulence even when the bucket device is operated excessively in the opening or closing direction. [Solution] The bucket control device includes a controller 70 that performs at least one of over-opening suppression control and over-closing suppression control. The over-opening suppression control is a control in which the controller 70 stops paying out the rope of the opening / closing drum, which is the drum responsible for opening and closing the bucket device 10, among the first winch drum DR1 and the second winch drum DR2, when the bucket device 10 is in an over-open state, being operated in the direction to open the bucket device 10 further from a predetermined open state. The over-closing suppression control is a control in which the controller 70 stops winding up the rope of the opening / closing drum when the bucket device 10 is in an over-closed state, being operated in the direction to close the bucket device 10 further from a predetermined closed state.

Description

Technical Field

[0001] The present disclosure relates to a bucket control device for opening and closing and raising and lowering a bucket device mounted on a construction machine such as a crane, a construction machine equipped with the bucket control device, and a bucket control method.

Background Art

[0002] Patent Document 1 and Patent Document 2 describe a bucket control device mounted on 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 raised and lowered according to the rotation of the first winch drum and the rotation of the second winch drum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in Patent Documents 1 and 2, an operation for further opening the bucket device may be performed even though the bucket device is already open, or an operation for further closing the bucket device may be performed even though the bucket device is already closed. In this case, excessive slack may occur in one of the winch ropes, leading to problems such as the ropes getting tangled and causing a mess.

[0005] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a bucket control device that can suppress malfunctions such as rope entanglement even when the bucket device is operated excessively in the opening direction or excessively in the closing direction, a construction machine equipped with the bucket control device, and a bucket control method. [Means for solving the problem]

[0006] The bucket control device according to the first embodiment is a control device for a construction machine comprising: a first winch drum for paying out and winding up a first winch rope; a second winch drum for paying out and winding up a second winch rope; a bucket device connected to the first and second winch ropes, which can be opened and closed and raised and lowered in accordance with the rotation of the first and second winch drums; a first winch operating device that is given an operation to rotate the first winch drum; and a second winch operating device that is given an operation to rotate the second winch drum. The bucket control device includes a controller that performs at least one of over-opening suppression control and over-closing suppression control. The over-opening suppression control is a control in which, when the bucket device is in an over-open state, being operated in the direction of further opening the bucket device from a predetermined open state, the controller stops paying out the rope from the opening / closing drum, which is one of the first and second winch drums responsible for opening and closing the bucket device. The over-closing suppression control is a control in which, when the bucket device is in an over-closed state, being operated in the direction of further closing the bucket device from a predetermined closed state, the controller stops winding up the rope from the opening / closing drum.

[0007] According to the first embodiment, when the bucket device is in an over-open state, the extension of the drum responsible for opening and closing the bucket device is stopped, and when the bucket device is in an over-closed state, the winding of the drum responsible for opening and closing the bucket device is stopped, thereby reducing slack in the winch rope and suppressing problems such as tangled rope winding.

[0008] A bucket control device according to a second embodiment preferably has the following additional features compared to a bucket control device according to a first embodiment. That is, in the second embodiment, the construction machine includes a first detector for detecting a first payout amount, which is the amount of the first winch rope paid out, or a first lifting value, which is the lifting value of the first winch rope; a second detector for detecting a second payout amount, which is the amount of the second winch rope paid out, or a second lifting value, which is the lifting value of the second winch rope; and a storage unit. The storage unit pre-stores a first reference value which is the difference between the amount of the first winch rope unwound and the amount of the second winch rope unwound when the bucket device is in the predetermined open state, and a second reference value which is the difference between the amount of the first winch rope unwound and the amount of the second winch rope unwound when the bucket device is in the predetermined closed state. Alternatively, the storage unit pre-stores a first lifting reference value which is the difference between the lifting height of the first winch rope and the lifting height of the second winch rope when the bucket device is in the predetermined open state, and a second lifting reference value which is the difference between the lifting height of the first winch rope and the lifting height of the second winch rope when the bucket device is in the predetermined closed state. The controller determines whether the bucket device is in either the over-open state or the over-closed state based on the relative difference which is the difference between the first payout amount and the second payout amount, the first reference value, and the second reference value. Alternatively, the controller determines whether the bucket device is in either the over-open state or the over-closed state based on the difference in lift values ​​which is the difference between the first lift value and the second lift value, the first lift reference value, and the second lift reference value.

[0009] According to the second embodiment, the first detector continuously detects the first payout amount or the first lifting height value, and the second detector continuously detects the second payout amount or the second lifting height value, thereby enabling real-time determination of whether the bucket device is in an over-open or over-closed state.

[0010] A bucket control device according to a third embodiment preferably has the following additional features compared to a bucket control device according to a second embodiment. That is, in a bucket device according to a third embodiment, the controller determines that the bucket device is in the over-open state if the relative difference is greater than the first reference value, and determines that the bucket device is in the over-closed state if the relative difference is less than the second reference value. Alternatively, the controller determines that the bucket device is in the over-open state if the difference in lifting value is greater than the first lifting reference value, and determines that the bucket device is in the over-closed state if the difference in lifting value is less than the second lifting reference value.

[0011] According to the third embodiment, it is possible to easily determine whether the bucket device is in an over-open or over-closed state from the relative difference, which is the difference between the first and second payout amounts. Alternatively, it is possible to easily determine whether the bucket device is in an over-open or over-closed state from the difference in lift values, which is the difference between the first lift value and the second lift value.

[0012] A bucket control device according to a fourth embodiment is preferably a bucket control device according to a second or third embodiment that further includes the following features. That is, in the fourth embodiment, the construction machine further includes a first proportional valve capable of stopping the rotation of the first winch drum and a second proportional valve capable of stopping the rotation of the second winch drum, and the controller, when it is determined that the bucket device is in the over-open state, inputs a command to the proportional valve of the first proportional valve and the second proportional valve that corresponds to the opening / closing drum to stop the rotation of the opening / closing drum in the unwinding direction, and the controller, when it is determined that the bucket device is in the over-closed state, inputs a command to the proportional valve of the first proportional valve and the second proportional valve that corresponds to the opening / closing drum to stop the rotation of the opening / closing drum in the winding direction.

[0013] According to the fourth aspect, if the bucket device is determined to be in an over-open state, a command is input to the proportional valve corresponding to the opening / closing drum responsible for opening and closing the bucket device to stop the rotation of the opening / closing drum in the unwinding direction, thereby stopping the rotation of the opening / closing drum and reducing the slack in the rope responsible for opening and closing the bucket device. Also, if the bucket device is determined to be in an over-closed state, a command is input to the proportional valve corresponding to the opening / closing drum responsible for opening and closing the bucket device to stop the rotation of the opening / closing drum in the winding direction, thereby stopping the rotation of the opening / closing drum and reducing the slack in the rope that supports the bucket device.

[0014] A bucket control device according to the fifth embodiment preferably further comprises the following features in a bucket control device according to any of the second to fourth embodiments. That is, in a bucket control device according to the fifth embodiment, the first reference value is set to the average of a first reference value set when the lifting height of the bucket device is at a predetermined maximum lifting height and a first reference value set when the lifting height of the bucket device is at a predetermined minimum lifting height; the second reference value is set to the average of a second reference value set when the lifting height of the bucket device is at the maximum lifting height and a second reference value set when the lifting height of the bucket device is at the minimum lifting height; the first lifting height reference value is set to the average of a first lifting height reference value set when the lifting height of the bucket device is at the maximum lifting height and a first lifting height reference value set when the lifting height of the bucket device is at the minimum lifting height; and the second lifting height reference value is set to the average of a second lifting height reference value set when the lifting height of the bucket device is at the maximum lifting height and a second lifting height reference value set when the lifting height of the bucket device is at the minimum lifting height.

[0015] According to the fifth aspect, the first reference value, second reference value, first lifting height reference value, and second lifting height reference value are all set to the average value of the value set when the bucket device is at its maximum lifting height and the value set when the bucket device is at its minimum lifting height. This reduces the influence of changes in the effective radius of the first and second winch drums due to changes in the winding layers of the first and second winch drums. As a result, the accuracy of determining the over-open and over-closed states of the bucket device is improved.

[0016] A bucket control device according to the sixth embodiment preferably has the following additional features in addition to the bucket control device according to any of the second to fifth embodiments. That is, in the bucket control device according to the sixth embodiment, the controller calculates a first change amount which is the difference between the first payout amount of the first winch rope when the bucket device is in the predetermined open state and the first payout amount of the first winch rope when the bucket device is in the predetermined closed state, and a second change amount which is the difference between the second payout amount of the second winch rope when the bucket device is in the predetermined open state and the second payout amount of the second winch rope when the bucket device is in the predetermined closed state, and if the first change amount is greater than the second change amount, the controller determines that the first winch rope is the rope responsible for opening and closing the bucket device, and if the first change amount is less than the second change amount, the controller determines that the second winch rope is the rope responsible for opening and closing the bucket device. The controller determines that the first winch rope is responsible for opening and closing the bucket device, or calculates a first lift change amount which is the difference between the first lift value of the first winch rope when the bucket device is in the predetermined open state and the first lift value of the first winch rope when the bucket device is in the predetermined closed state, and a second lift change amount which is the difference between the second lift value of the second winch rope when the bucket device is in the predetermined open state and the second lift value of the second winch rope when the bucket device is in the predetermined closed state. If the first lift change amount is greater than the second lift change amount, the controller determines that the first winch rope is responsible for opening and closing the bucket device, and if the first lift change amount is less than the second lift change amount, the controller determines that the second winch rope is responsible for opening and closing the bucket device.

[0017] According to the sixth aspect, by determining the rope responsible for opening and closing the bucket device, it is possible to prevent the operator from mistakenly using the wrong rope.

[0018] The bucket control device according to the seventh embodiment preferably further comprises the following features in addition to the bucket control device according to any of the second to sixth embodiments. That is, in the seventh embodiment, the construction machine further comprises an alarm device, and the controller activates the alarm device when it is determined that the bucket device is in the over-open state or the over-closed state.

[0019] According to the seventh aspect, if the bucket device is determined to be in an over-open or over-closed state, the alarm device will activate and generate an alarm sound, allowing the operator to quickly recognize that the bucket device is in an over-open or over-closed state.

[0020] The bucket control device according to the eighth embodiment comprises a first winch drum for paying out and winding up a first winch rope, a second winch drum for paying out and winding up a second winch rope, a bucket device connected to the first and second winch ropes and capable of opening and closing and moving up and down in accordance with the rotation of the first and second winch drums, a first winch operating device that is given an operation to rotate the first winch drum, a second winch operating device that is given an operation to rotate the second winch drum, and a controller that performs over-opening suppression control, wherein the over-opening suppression control is a control in which, when the bucket device is in an over-open state, being operated in the direction of further opening the bucket device from a predetermined open state, the controller stops paying out the rope of the opening / closing drum, which is the drum responsible for opening and closing the bucket device, among the first and second winch drums.

[0021] According to the eighth aspect, when the bucket device is in an over-open state, the extension of the drum responsible for opening and closing the bucket device is stopped, which reduces slack in the winch rope and suppresses problems such as rope entanglement.

[0022] The bucket control device according to the ninth aspect includes 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 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, a first winch operating device to which an operation for rotating the first winch drum is applied, a second winch operating device to which an operation for rotating the second winch drum is applied, and a controller that performs over-closure suppression control. The over-closure suppression control is a control in which the controller stops the winding of the rope of the opening and closing drum when the bucket device is in an over-closed state in which the bucket device is further operated in the direction of closing the bucket device from a predetermined closed state.

[0023] According to the ninth aspect, when the bucket device is in an over-closed state, the winding of the drum responsible for opening and closing the bucket device is stopped, thereby reducing the slack of the winch rope and suppressing problems such as the rope being wound up disorderly.

[0024] A construction machine equipped with the bucket control device according to the tenth aspect includes the first winch drum, the second winch drum, the bucket device, the first winch operating device, the second winch operating device, and the bucket control device according to any one of the first to seventh aspects.

[0025] According to the tenth aspect, when the bucket device is in an over-opened state, the payout of the drum responsible for opening and closing the bucket device is stopped, and when the bucket device is in an over-closed state, the winding of the drum responsible for opening and closing the bucket device is stopped, thereby reducing the slack of the rope and suppressing problems such as the rope being wound up disorderly. It is possible to provide a construction machine equipped with a bucket control device.

[0026] The 11th aspect is a bucket control method for a construction machine, comprising: 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 connected to the first winch rope and the second winch rope, which can be opened and closed and lifted and lowered according to the rotation of the first winch drum and the rotation of the second winch drum; a first winch operating device to which an operation for rotating the first winch drum is given; and a second winch operating device to which an operation for rotating the second winch drum is given. When the bucket device is in an over-opened state where the bucket device is further operated in the opening direction from a predetermined opened state, the controller stops the payout of the rope of the opening and closing drum, which is the drum responsible for opening and closing the bucket device, among the first winch drum and the second winch drum. And when the bucket device is in an over-closed state where the bucket device is further operated in the closing direction from a predetermined closed state, the controller stops the winding up of the rope of the opening and closing drum. At least one of these is included.

[0027] According to the 11th aspect, when the bucket device is in an over-opened state, the payout of the drum responsible for opening and closing the bucket device is stopped. When the bucket device is in an over-closed state, the winding up of the drum responsible for opening and closing the bucket device is stopped, thereby reducing the slack of the winch rope and suppressing problems such as rope entanglement, and a bucket control method can be provided.

Advantages of the Invention

[0028] According to the present disclosure, even when an over-opening operation and an over-closing operation of the bucket device are performed, a bucket control device that can suppress the bucket device from being in an over-opened state and an over-closed state and a construction machine equipped with the bucket control device can be provided.

Brief Description of the Drawings

[0029] [Figure 1] It is a side view showing a crane equipped with a bucket control device according to an embodiment of the present disclosure. [Figure 2] This is a block diagram outlining the functional configuration of the aforementioned crane. [Figure 3] This is a diagram showing the hydraulic circuit installed in the aforementioned crane. [Figure 4] This is a diagram illustrating the opening and closing operation of the bucket device provided by the crane. [Figure 5] This is a block diagram illustrating the schematic functional configuration of the bucket control device. [Figure 6] This diagram shows the state of the bucket device in the fully open and fully closed positions. [Figure 7] This figure shows an example of the change in the degree of opening and closing of the bucket device during crane operation. [Figure 8] This figure shows the state of the bucket device in an over-open and over-closed state. [Figure 9] This flowchart illustrates the control operation of the controller that suppresses over-opening and over-closing of the bucket device. [Figure 10] This is an example of an image displayed on the monitor when setting the fully open and fully closed states of the bucket device. [Figure 11] This diagram shows the bucket device at its maximum lifting height and at its minimum lifting height. [Figure 12] This is an example of an image displayed on the monitor when moving the bucket device to its maximum and minimum lifting heights. [Figure 13] This flowchart shows the control operations performed when determining the rope responsible for opening and closing the bucket device. [Figure 14] This is an example of an image displayed on the monitor when verifying whether the judgment result for the rope responsible for opening and closing is correct. [Modes for carrying out the invention]

[0030] Preferred embodiments of this disclosure will be described with reference to the drawings.

[0031] [First Embodiment] Figure 1 shows a crane 100, which is a construction machine according to the above embodiment. This crane 100 comprises a lower body 101, an upper slewing body 102 that is rotatably supported on the lower body 101, a luffing member 104 that is luffably supported on the upper slewing body 102, a first point sheave 105 and a second point sheave 106 attached to the tip of the luffing member 104, a plurality of winches arranged on the lower body 101 or the upper slewing body 102, a bucket device 10, and a bucket control device.

[0032] The lower body 101 is equipped with a travel device, such as a crawler track, and is configured to be self-propelled. However, the lower body may be composed of a structure such as a support base that rotatably supports the upper slewing body 102 and is not self-propelled. The upper slewing body 102 comprises 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 include a first winch WC1, a second winch WC2, and a luffing winch WC3.

[0033] The luffing member 104 consists of a boom supported on a slewing frame 103 so as to be luffable. However, the luffing member may also 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 positioned 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 wrapped around the lower spreader 110 and the upper spreader 109. The luffing winch WC3 is positioned 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 distance between the upper spreader 109 and the lower spreader 110 by winding in or unwinding the luffing rope 111. The luffing member 104 is raised or lowered in accordance with the reduction or increase in this distance.

[0034] Figure 2 is a block diagram showing the functional configuration of the bucket control device. Figure 3 is a diagram showing the hydraulic circuit provided by the crane 100.

[0035] The first winch WC1 and the second winch WC2 are driven to open, close, and raise the bucket device 10. Specifically, as shown in Figures 1 to 3, the first winch WC1 has a first winch drum DR1 around which the 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 reduction gear 47. Similarly, the second winch WC2 has a second winch drum DR2 around which the 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 reduction gear 47. The first winch rope R1 is an opening and closing rope for opening and closing the bucket device 10, and the second winch rope R2 is a support rope for supporting the bucket device 10. The first winch drum DR1 is an opening / closing drum that pays out and retracts the first winch rope R1 (opening / closing rope), and the second winch drum DR2 is a support drum that pays out and retracts the second winch rope R2 (support rope).

[0036] The first winch drum DR1 is supported by a support member (not shown) so as to be rotatable around a horizontal axis, allowing for the unwinding and winding of the first winch rope R1. The second winch drum DR2 is supported by a support member (not shown) so as to be rotatable around a horizontal axis, allowing for the unwinding and winding of the second winch rope R2.

[0037] The first point sheave 105 and the second point sheave 106 are arranged side by side and attached to the tip of the luffing 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 and R2 are connected to the bucket device 10.

[0038] The bucket device 10 is a working device known as a clamshell bucket. The bucket device 10 is connected to the first winch rope R1 and the second winch rope R2, and can be opened and closed and raised and lowered in accordance with the rotation of the first winch drum DR1 and the second winch drum DR2. The right diagram of Figure 4 shows the bucket device 10 in the open state, and the left diagram of Figure 4 shows the bucket device 10 in the closed state. The bucket device 10 comprises an upper member 11, a lower member 16 positioned 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.

[0039] The pair of link members 12, 12 are arranged horizontally, spaced apart from each other. The upper ends of the pair of link members 12, 12 are connected to the upper member 11 so as to be rotatable around 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 around 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 around a horizontal axis.

[0040] The lower sheave 14 is supported by the lower member 16 so as to be rotatable around a horizontal axis. Each of the pair of buckets 13, 13 has a supported portion that is supported by the lower member 16 so as to be rotatable around a horizontal axis. The upper sheave 15 is supported by the upper member 11 so as to be rotatable around a horizontal axis.

[0041] The pair of buckets 13, 13 have a storage space capable of accommodating materials such as soil and sand. The pair of buckets 13, 13 can rotate around the supported part, allowing them to be displaced between a state where the lower ends of the buckets 13, 13 are adjacent to each other (closed state) and a state where the lower ends of the buckets 13, 13 are separated horizontally (open state). The pair of link members 12, 12 support the buckets 13, 13 and rotate relative to the upper member 11 in accordance with the displacement of the buckets 13, 13. By maintaining the closed state, the pair of buckets 13, 13 can hold the materials to be transported contained in the storage space. By switching from the closed state to the open state, the pair of buckets 13, 13 can discharge the materials to be transported from the storage space to the outside of the buckets 13, 13.

[0042] The first winch rope R1 is routed around the lower sheave 14 and the upper sheave 15, and the end of the first winch rope R1 is fixed to either the upper member 11 or the lower member 16. The end of the second winch rope R2 is fixed to the upper member 11.

[0043] The first and second winch motors 34 and 35 are variable displacement hydraulic motors connected to the hydraulic pump 31. The first winch motor 34 operates by receiving hydraulic fluid discharged from the hydraulic pump 31 to rotate the first winch drum DR1 in either the forward or reverse direction, i.e., the unwinding direction and the winding direction. Similarly, the second winch motor 35 operates by receiving hydraulic fluid discharged from the hydraulic pump 31 to rotate the second winch drum DR2 in either the forward or reverse direction, i.e., the unwinding direction and the winding direction. This enables the opening and closing and raising and lowering of the bucket device 10 through the cooperation of the first winch WC1 and the second winch WC2. The hydraulic pump 31 is driven by a power source such as an engine (not shown).

[0044] The reduction gear 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 reduction gear 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 reduction gears 47 each have, for example, a planetary gear mechanism.

[0045] The first clutch brake 40A can switch 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 unfurled 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.

[0046] Similarly, the second clutch brake 40B can switch 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 unfurled 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.

[0047] The aforementioned connection state is one in which the first and second winch ropes R1 and R2 can be unwound and wound up by the driving force 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 aforementioned connection state, the driving force of the first and second winch motors 34 and 35 is transmitted to the first and second winch drums DR1 and DR2, respectively, via the reduction gears 47 and 47. When the first and second winch drums DR1 and DR2 rotate, the first and second winch ropes R1 and R2 are unwound or wound up.

[0048] The free state is a state in which the first and second winch ropes R1 and R2 can be unfurled from the first and second winch drums DR1 and DR2 by the tension of the first and second winch ropes R1 and R2, that is, a state in which the bucket device 10 can free fall. In other words, the free state is a state in which the first and second winch ropes R1 and R2 can be unfurled from the first and second winch drums DR1 and DR2 without rotating the first and second winch motors 34 and 35 in the unfurling direction of the first and second winch ropes R1 and R2.

[0049] Furthermore, the first clutch brake 40A can apply a first braking force to the first winch drum DR1, that is, it 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, it can brake the second winch drum DR2.

[0050] When the first braking force against the rotation of the first winch drum DR1 exceeds a predetermined magnitude, the first winch drum DR1 is braked, making it 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 exceeds a predetermined magnitude, the second winch drum DR2 is braked, making it 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 are sufficient to maintain the bucket device 10 in a stationary state without free-falling, and to stop the bucket device 10 if it is free-falling.

[0051] In this embodiment, the first clutch brake 40A and the second clutch brake 40B are each so-called wet brakes and include a piston 42 driven by hydraulic pressure supplied from a pilot hydraulic power source P, and a plurality of brake discs 41 (a plurality of clutch plates). Each of the plurality of brake discs 41 is, for example, a friction plate immersed in hydraulic fluid.

[0052] The multiple brake discs 41 can be switched between a state in which the multiple brake discs 41 are in contact with each other and a state in which the multiple brake discs 41 are separated from each other by the operation of the piston 42. When the multiple brake discs 41 are separated from each other, the first clutch brake 40A and the second clutch brake 40B are in the free state, which allows the bucket device 10 to descend (free fall) by its own weight. The first clutch brake 40A and the second clutch brake 40B are in the connected state when the multiple brake discs 41 come into contact with each other.

[0053] More specifically, each of the first clutch brake 40A and the second clutch brake 40B is equipped with a spring 46, and each of the first clutch brake 40A and the second clutch brake 40B has a pair of oil chambers 43, 44 formed therein, and the piston 42 has a flange 45 that separates the pair of oil chambers 43, 44. When the hydraulic pressure applied to the pair of oil chambers 43, 44 from the pilot hydraulic power source P is the same, the spring 46 biases the piston 42 so that the multiple brake discs 41 come into contact with each other. When the hydraulic pressure applied to one oil chamber 44 from the pilot hydraulic power source P becomes greater than the hydraulic pressure applied to the other oil chamber 43 by a predetermined amount or more, the multiple brake discs 41 come apart from each other.

[0054] The bucket control device is a device for opening, closing, and raising / lowering the bucket device 10 by controlling the drive of the first winch drum DR1 and the second winch drum DR2. This bucket control device comprises a first control valve 32, a second control valve 33, a first payout proportional valve 61A, a first winding proportional valve 61B, a second payout proportional valve 63A, a second winding 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 this embodiment, each of the proportional valves 61A, 61B, 62, 63A, 63B, and 64 is an electromagnetic proportional pressure reducing valve that can linearly adjust the output pressure.

[0055] 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 composed of a hydraulic pilot switching valve having a pair of pilot ports.

[0056] The pair of pilot ports are a pay-out pilot port and a retraction pilot port. When no pilot pressure is applied to either of the pilot ports, the first and second control valves 32 and 33 are held in a neutral position, disconnecting the winch motor corresponding to the control valve (hereinafter referred to as the "corresponding winch motor") among the first and second winch motors 34 and 35 from the hydraulic pump 31.

[0057] Each of the first and second control valves 32 and 33 opens when pilot pressure is applied to the unwinding pilot port to form an oil passage for rotating the corresponding winch motor in the unwinding direction, that is, an oil passage for supplying hydraulic fluid from the hydraulic pump 31 to the corresponding winch motor in the unwinding direction. Each of the first and second control valves 32 and 33 opens when pilot pressure is applied to the rewinding pilot port to form an oil passage for rotating the corresponding winch motor in the rewinding direction, that is, an oil passage for supplying hydraulic fluid from the hydraulic pump 31 to the corresponding winch motor in the rewinding direction. The opening degree of each of the first and second control valves 32 and 33 increases with increasing pilot pressure to allow hydraulic fluid to flow at a flow rate corresponding to the pilot pressure input to the control valve.

[0058] The first dispensing proportional valve 61A is interposed between a pilot hydraulic power source (not shown) and the dispensing pilot port of the first control valve 32. When a first dispensing command, which is an electrical signal, is input to the proportional valve 61A from the controller 70, the valve opens to allow a pilot pressure proportional to the first dispensing command to be input to the dispensing pilot port. The first retracting proportional valve 61B is interposed between the pilot hydraulic power source and the retracting pilot port of the first control valve 32. When a first retracting command, which is an electrical signal, is input to the proportional valve 61B from the controller 70, the valve opens to allow a pilot pressure proportional to the first retracting command to be input to the retracting pilot port.

[0059] Similarly, the second dispensing proportional valve 63A is interposed between a pilot hydraulic power source (not shown) and the dispensing pilot port of the second control valve 33, and opens to allow a pilot pressure proportional to the second dispensing command to be input to the dispensing pilot port when the controller 70 inputs a second dispensing command, which is an electrical signal, to the proportional valve 63A. The second retracting proportional valve 63B is interposed between the pilot hydraulic power source and the retracting pilot port of the second control valve 33, and opens to allow a pilot pressure proportional to the second retracting command to be input to the retracting pilot port when the controller 70 inputs a second retracting command, which is an electrical signal, to the proportional valve 63B.

[0060] As described above, the first control valve 32, the first dispensing proportional valve 61A, and the first retracting proportional valve 61B constitute a first speed controller that changes the flow rate and direction of the hydraulic fluid 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 controller changes the speed at which the first winch motor 34 rotates the first winch drum DR1. Similarly, the second control valve 33, the second dispensing proportional valve 63A, and the second retracting proportional valve 63B constitute a second speed controller that changes the flow rate and direction of the hydraulic fluid 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 controller changes the speed at which the second winch motor 35 rotates the second winch drum DR2.

[0061] Even when a first unwinding operation is applied to the first winch operating lever 51A of the first winch operating device 51, as described later, if the controller 70 inputs a command to the first unwinding proportional valve 61A to set the pilot pressure input to the unwinding pilot port of the first control valve 32 to a predetermined value or less (for example, zero), the spool of the first control valve 32 moves to the neutral position. As a result, the supply of hydraulic fluid to the first winch motor 34 is stopped, and the rotation of the first winch motor 34 stops, thereby stopping the rotation of the first winch drum DR1. Note that when stopping the rotation of the first winch drum DR1 in the unwinding direction, the controller 70 may input the command to the first unwinding proportional valve 61A and also input a command to the first winding proportional valve 61B to set the pilot pressure input to the winding pilot port of the first control valve 32 to a predetermined value or less (for example, zero).

[0062] Even when a first winding operation is applied to the first winch operating lever 51A of the first winch operating device 51, if the controller 70 inputs a command to the first winding proportional valve 61B to set the pilot pressure input to the winding pilot port of the first control valve 32 to a predetermined value or less (for example, zero), the spool of the first control valve 32 moves to the neutral position. As a result, the supply of hydraulic fluid to the first winch motor 34 is stopped, the rotation of the first winch motor 34 is stopped, and the rotation of the first winch drum DR1 is stopped. Note that when stopping the rotation of the first winch drum DR1 in the winding direction, the controller 70 may input the command to the first winding proportional valve 61B and also input a command to the first unwinding proportional valve 61A to set the pilot pressure input to the unwinding pilot port of the first control valve 32 to a predetermined value or less (for example, zero).

[0063] As described above, the first control valve 32 also functions as a first stop device that stops the rotation of the first winch drum DR1. Furthermore, the first payout proportional valve 61A and the first winding proportional valve 61B are examples of first proportional valves capable of stopping the rotation of the first winch drum DR1.

[0064] Even when a second unwinding operation is applied to the second winch operating lever 53A of the second winch operating device 53 (described later), if the controller 70 inputs a command to the second unwinding proportional valve 63A to set the pilot pressure input to the unwinding pilot port of the second control valve 33 to a predetermined value or less (for example, zero), the spool of the second control valve 33 moves to the neutral position. As a result, the supply of hydraulic fluid to the second winch motor 35 is stopped, the rotation of the second winch motor 35 is stopped, and the rotation of the second winch drum DR2 is stopped. Note that when stopping the rotation of the second winch drum DR2 in the unwinding direction, the controller 70 may input the command to the second unwinding proportional valve 63A and also input a command to the second winding proportional valve 63B to set the pilot pressure input to the winding pilot port of the second control valve 33 to a predetermined value or less (for example, zero).

[0065] Even when the second winch operating lever 53A of the second winch operating device 53 is assigned a first winding operation, if the controller 70 inputs a command to the second winding proportional valve 63B to set the pilot pressure input to the winding pilot port of the second control valve 33 to a predetermined value or less (for example, zero), the spool of the second control valve 33 moves to the neutral position. As a result, the supply of hydraulic fluid to the second winch motor 35 is stopped, the rotation of the second winch motor 35 is stopped, and the rotation of the second winch drum DR2 is stopped. Note that when stopping the rotation of the second winch drum DR2 in the winding direction, the controller 70 may input the command to the second winding proportional valve 63B and also input a command to the second unwinding proportional valve 63A to set the pilot pressure input to the unwinding pilot port of the second control valve 33 to a predetermined value or less (for example, zero).

[0066] As described above, the second control valve 33 also functions as a second stop device that stops the rotation of the second winch drum DR2. Furthermore, the second payout proportional valve 63A and the second rewind proportional valve 63B are examples of second proportional valves capable of stopping the rotation of the second winch drum DR2.

[0067] The first brake proportional valve 62 is interposed between the pilot hydraulic power source P and the first clutch brake 40A. When the first brake command, which is an electrical signal, is input to the proportional valve 62 from the controller 70, the valve opens to allow hydraulic pressure (first pilot pressure) proportional to the first brake command to be input to the oil chamber 43 of the first clutch brake 40A. As a result, the first brake proportional valve 62 can switch the state of the first clutch brake 40A between the free state and the connected state.

[0068] Similarly, the second brake proportional valve 64 is interposed between the pilot hydraulic power source P and the second clutch brake 40B. When a second brake command, which is an electrical signal, is input to the proportional valve 64 from the controller 70, the valve opens to allow hydraulic pressure (second pilot pressure) proportional to the second brake command to be input to the oil chamber 43 of the second clutch brake 40B. As a result, the second brake proportional valve 64 can switch the state of the second clutch brake 40B between the free state and the connected state.

[0069] 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 body 51B. The second winch operating device 53 has a second winch operating lever 53A and a second winch operating device body 53B. The first brake operating device 52 has a first brake operating pedal 52A and a first brake operating device body 52B. The second brake operating device 54 has a second brake operating pedal 54A and a second brake operating device body 54B.

[0070] In the following description, the first winch rope R1 may be referred to as the main hoisting rope, the second winch rope R2 as the auxiliary hoisting rope, the first winch drum DR1 as the main hoisting drum, and the second winch drum DR2 as the auxiliary hoisting drum. Also, the first winch operating lever 51A may be referred to as the main hoisting lever, and the second winch operating lever 53A as the auxiliary hoisting lever. Also, the first brake operating pedal 52A may be referred to as the main hoisting pedal, and the second brake operating pedal 54A as the auxiliary hoisting pedal. In the crane 100, instead of the bucket device 10, a main hoisting hook (not shown) may be attached to the end of the first winch rope R1 (main hoisting rope), and an auxiliary hoisting hook (not shown) may be attached to the end of the second winch rope R2 (auxiliary hoisting rope). "Main slings" are primarily used for heavy loads, such as for lifting heavy loads, while "supplementary slings" are primarily used as auxiliary slings for lifting lighter loads.

[0071] The first winch operating device 51 is a device that is operated by the operator to rotate the first winch drum DR1. The first winch operating lever 51A is an operating member that is rotated by the operator to specify the drive speed (rotational speed) of the first winch drum DR1. Specifically, the first winch operating lever 51A is provided with either a first payout operation to rotate the first winch drum DR1 in the payout direction to pay out the first winch rope R1, or a first winding operation to rotate the first winch drum DR1 in the winding direction to wind up the first winch rope R1.

[0072] The first winch operating device body 51B inputs a command signal to the controller 70 to command a rotational speed corresponding to the amount of operation (lever operation amount) of the rotational operation (first payout operation or first winding operation) applied to the first winch operating lever 51A.

[0073] Similarly, the second winch operating device 53 is a device to which the operator can perform a rotational operation to rotate the second winch drum DR2. The second winch operating lever 53A is an operating member to which the operator can perform a rotational operation to specify the drive speed (rotational speed) of the second winch drum DR2. Specifically, the second winch operating lever 53A is provided with either a second payout operation to rotate the second winch drum DR2 in the payout direction to pay out the second winch rope R2, or a second winding operation to rotate the second winch drum DR2 in the winding direction to wind up the second winch rope R2.

[0074] The second winch operating device body 53B inputs a command signal to the controller 70 to command a rotational speed corresponding to the amount of operation (lever operation amount) of the rotational operation (second payout operation or second winding operation) applied to the second winch operating lever 53A.

[0075] The first brake operation pedal 52A is an operating member to which the operator performs a pedal operation (an example of a first brake operation) to specify the first brake force to the first winch drum DR1. The first brake operation device body 52B inputs a command signal to the controller 70 to command a brake force of a magnitude corresponding to the amount of the first pedal operation (pedal operation amount) applied to the first brake operation pedal 52A.

[0076] The second brake operation pedal 54A is an operating member to which the operator performs a pedal operation (an example of a second brake operation) to specify the second brake force applied to the second winch drum DR2. The second brake operation device body 54B inputs a command signal to the controller 70 to command a brake force of a magnitude corresponding to the amount of the second pedal operation (pedal operation amount) applied to the second brake operation pedal 54A.

[0077] The bucket control device further includes, as shown in Figure 2, 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 a non-synchronized control mode switch 90 (single-sided on / off switch 90) and a bucket assist mode switch 91. The first rotation sensor 81 is an example of the first detector of this disclosure, and the second rotation sensor 82 is an example of the second detector of this disclosure.

[0078] The first rotation sensor 81 generates a first detection signal for the first rotation amount nm, which is the amount of rotation of the first winch drum DR1, and inputs it to the controller 70. The second rotation sensor 82 generates a second detection signal for the second rotation amount na, which is the amount of rotation of the second winch drum DR2, and inputs it to the controller 70. The first rotation amount nm and the second rotation amount na are rotation amounts from a set reference value, respectively. Note that the first rotation sensor 81 may be a sensor that generates a detection signal for the amount of rotation of the first point sheave 105 instead of the amount of rotation of the first winch drum DR1, and the second rotation sensor 82 may be a sensor that generates a detection signal for the amount of rotation of the second point sheave 106 instead of the amount of rotation of the second winch drum DR2.

[0079] In this embodiment, the controller 70 sets the control mode of the controller 70 to one of a predetermined number of control modes based on a command signal input from the control mode setting unit. In this embodiment, the number of control modes includes 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 number of control modes may further include other control modes.

[0080] The bucket assist mode is a control mode in which the controller 70 performs assist control to enable the operator to perform at least one of the operations of opening / closing and raising / lowering the bucket device 10 with simple operation. The non-assist mode is a control mode in which the above-mentioned assist control is not performed. Assist control includes main auxiliary synchronization control and free synchronization control.

[0081] The above-described main auxiliary synchronization control is a control that synchronizes the operation of the first winch drum DR1 and the operation of the second winch drum DR2. In the main auxiliary synchronization control, the controller 70 controls the operation of the first winch drum DR1 and the operation of the second winch drum DR2 based on the operation given to the first winch operating device 51.

[0082] For example, in main-auxiliary synchronization control, when an unwinding operation is applied to the first winch operating device 51, the controller 70 performs the following opening down control or unwinding control. In the above opening down control, the controller 70 controls the operation of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 descends while maintaining the open state of the bucket device 10. In the above closing down control, the controller 70 controls the operation of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 descends while maintaining the closed state of the bucket device 10. Furthermore, in main-auxiliary synchronization control, when a winding operation is applied to the first winch operating device 51, the controller 70 performs the following opening up control or closing up control. In the above opening up control, the controller 70 controls the operation of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 rises while maintaining the open state of the bucket device 10. In the above closing control, the controller 70 controls the operation of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 is maintained in a closed state.

[0083] The above-described free-synchronization control is a control that motivates the first braking force of the first winch drum DR1 and the second braking force of the second winch drum DR2. In free-synchronization control, the controller 70 controls the first braking force of the first winch drum DR1 and the second braking force of the second winch drum DR2 based on the amount of operation of the first brake operating device 52.

[0084] For example, in free-synchronized control, if a braking operation that reduces the first braking force is applied to the first brake operating device 52, the controller 70 performs the following opening-down control or closing-down control. In the opening-down control, the controller 70 adjusts the first and second braking forces so that the bucket device 10 descends by its own weight while maintaining the open state of the bucket device 10. In the closing-down control, the controller 70 adjusts the first and second braking forces so that the bucket device 10 descends by its own weight while maintaining the closed state of the bucket device 10.

[0085] In this embodiment, the control mode is set to bucket assist mode when the bucket assist mode switch 91 is ON, and the control mode is set to non-assist mode when the bucket assist mode switch 91 is OFF. In bucket assist mode, the control mode is set to non-synchronized control mode when the non-synchronized control mode switch 90 is ON, and the control mode is set to synchronized control mode when the non-synchronized control mode switch 90 is OFF.

[0086] In this embodiment, in the synchronization control mode, synchronization control such as main and auxiliary synchronization control and free synchronization control is performed. The operation of the bucket device 10 in the synchronization control mode includes a "closed-up" operation, which is the operation of raising the bucket device 10 with the bucket device 10 closed; an "opened-up" operation, which is the operation of raising the bucket device 10 with the bucket device 10 open; an "opened-down" operation, which is the operation of lowering the bucket device 10 with the bucket device 10 open; and a "closed-down" operation, which is the operation of lowering the bucket device 10 with the bucket device 10 closed.

[0087] Figure 5 is a block diagram illustrating the main components of the control function of the controller 70. The controller 70 controls the driving of the first winch WC1 and the second winch WC2 to open, close and raise / lower the bucket device 10. The controller 70 has a computer including a central processing unit (such as a CPU) and a storage unit 78 consisting of ROM and RAM, and performs various processes including opening, closing, raising, and lowering the bucket device 10. The controller 70 has a brake force adjustment unit 71, a drum operation control unit 72, an opening / closing state determination unit 73, an over-opening / closing suppression unit 74, a screen display control unit 75, a notification unit 76, a condition setting unit 77, a storage unit 78, and an opening / closing rope determination unit 79. These functions are realized when the processing unit executes a control program stored in the storage unit 78.

[0088] The controller 70 receives various command signals, including the first rotation amount nm of the first winch drum DR1 detected by the first rotation sensor 81, the second rotation amount na of the second winch drum DR2 detected by the second rotation sensor 82, an ON command signal that switches the control mode output from the non-synchronized control mode switch 90 to non-synchronized control mode, an ON command signal that switches the control mode output from the bucket assist mode switch 91 to bucket assist mode, and an ON command signal that activates the monitor 120 output from the monitor switch 92.

[0089] Furthermore, the controller 70 receives command signals corresponding to the operator's operations (operator operations in Figure 5). Specifically, the controller 70 receives command signals corresponding to the operator's lever operation amount output from the first winch operating device body 51B, command signals corresponding to the operator's lever operation amount output from the second winch operating device body 53B, command signals corresponding to the operator's brake operation amount output from the first brake operating device body 52B, and command signals corresponding to the operator's brake operation amount output from the second brake operating device body 54B (see Figure 2).

[0090] The controller 70 outputs command signals to various proportional valves (61A, 61B, 62, 63A, 63B, 64) calculated by the brake force adjustment unit 71 and the drum motion control unit 72, command signals related to the screen display of the monitor 120, and command signals to generate an alarm sound in the alarm device 126.

[0091] The brake force adjustment unit 71 adjusts the first brake force applied to the first winch drum DR1 and the second brake force applied to the second winch drum DR2. For example, when the control mode is set to synchronized control mode, a first brake operation that reduces the first brake force is applied to the first brake operation pedal 52A, and it is determined that the bucket device 10 is in an open state, the brake force adjustment unit 71 performs the following opening down control. In the opening down control, the first brake force and the second brake force are controlled so that the bucket device 10 descends by its own weight while maintaining the open state of the bucket device 10. Furthermore, when the control mode is set to synchronized control mode, a first brake operation that reduces the first brake force is applied to the first brake operation pedal 52A, and it is determined that the bucket device 10 is in a closed state, the brake force adjustment unit 71 performs the following closing down control. In the closing down control, the brake force adjustment unit 71 adjusts the first brake force and the second brake force so that the bucket device 10 descends while maintaining the closed state of the bucket device 10.

[0092] The drum operation control unit 72 controls the operation of the first winch drum DR1 and the second winch drum DR2. In the main auxiliary synchronization control in synchronization control mode, the operation of the first winch drum DR1 and the second winch drum DR2 is controlled based on the rotational operation applied to the first winch operating device 51.

[0093] Specifically, the drum operation control unit 72 controls the operation of the first winch drum DR1 and the second winch drum DR2 so that, for example, when the control mode is set to synchronized control mode and a first unwinding operation is applied to the first winch operating lever 51A of the first winch operating device 51, the bucket device 10 descends while maintaining its open / closed state. Also, when the control mode is set to synchronized control mode and a first winding operation is applied to the first winch operating lever 51A of the first winch operating device 51, the drum operation control unit 72 controls the operation of the first winch drum DR1 and the second winch drum DR2 so that the bucket device 10 rises while maintaining its open / closed state.

[0094] [Over-opening / closing suppression control] The controller 70 performs over-opening / closing suppression control. This over-opening / closing suppression control includes over-opening suppression control and over-closing suppression control. The over-opening suppression control is a control in which the controller 70 stops paying out the rope from the opening / closing drum, which is the drum responsible for opening and closing the bucket device 10, when the bucket device 10 is in an over-open state, being operated in the direction of opening the bucket device from a predetermined open state. The over-closing suppression control is a control in which the controller 70 stops winding up the rope from the opening / closing drum, when the bucket device 10 is in an over-closed state, being operated in the direction of closing the bucket device from a predetermined closed state. Specifically, it is as follows.

[0095] The opening / closing state determination unit 73 calculates the degree of opening / closing α of the bucket device 10 and determines the opening / closing state (degree of opening / closing) of the bucket device 10 from the calculated degree of opening / closing α. The opening / closing state determination unit 73 calculates the degree of opening / closing α from the following equation (1). In equation (1), ΔL is the difference between the first payout amount Lm of the first winch rope R1 and the second payout amount La of the second winch rope R2 (hereinafter, relative difference ΔL), and is calculated from the following equation (2). In the following explanation, the first payout amount Lm of the first winch rope R1 and the second payout amount La of the second winch rope R2 are considered positive when the bucket device 10 is being lowered (i.e., when the bucket device 10 is descending), and the signs of the first payout amount Lm and the second payout amount La are considered negative when the bucket device 10 is being raised (i.e., when the bucket device 10 is rising).

[0096] α=(ΔL-ΔLmin) / (ΔLmax-ΔLmin)×100 (1) ΔL = Lm - La ···(2)

[0097] In equation (1), ΔLmax is the relative difference (hereinafter referred to as the maximum relative difference ΔLmax) between the amount Lm of the first winch rope R1 and the amount La of the second winch rope R2 when the bucket device 10 is fully open (hereinafter referred to as the fully open state). Also, ΔLmin is the relative difference (hereinafter referred to as the minimum relative difference ΔLmin) between the amount Lm of the first winch rope R1 and the amount La of the second winch rope R2 when the bucket device 10 is fully closed (hereinafter referred to as the fully closed state). The maximum relative difference ΔLmax and the minimum relative difference ΔLmin are set in advance by the operator. The method for setting the maximum relative difference ΔLmax and the minimum relative difference ΔLmin will be described later. The fully open state is an example of a predetermined open state in this disclosure, and the fully closed state is an example of a predetermined closed state in this disclosure.

[0098] The opening / closing state determination unit 73 calculates the degree of opening / closing α of the bucket device 10 by applying the relative difference ΔL, which is calculated as it occurs, the maximum relative difference ΔLmax when the bucket device 10 is in the fully open state, and the minimum relative difference ΔLmin when the bucket device 10 is in the fully closed state, to equation (1). From equation (1), it is normalized so that when the relative difference ΔL is the maximum relative difference ΔLmax, the degree of opening / closing α is 100%, and when the relative difference ΔL is the minimum relative difference ΔLmin, the degree of opening / closing α is 0%.

[0099] Figure 6 shows the state of the bucket device 10 in the fully open and fully closed states. The right diagram in Figure 6 shows the fully open state, and the left diagram in Figure 6 shows the fully closed state. In the fully open state of the bucket device 10 shown in the right diagram of Figure 6, the first winch rope R1 is loose, and the bucket device 10 is supported by the second winch rope R2. At this time, the lower ends of the pair of buckets 13 of the bucket device 10 are furthest apart. As the first winch rope R1 is wound up from this state, the first winch rope R1 becomes taut, and as the first winch rope R1 is further wound up, the bucket device 10 is gradually closed. When the bucket device 10 is completely closed, it is in the state shown in the left diagram of Figure 6, where the first winch rope R1 is taut, while the second winch rope R2 is loose. At this time, the bucket device 10 is supported by the first winch rope R1, and the lower ends of the pair of buckets 13 of the bucket device 10 are adjacent to each other. The relative difference ΔL increases as the bucket device 10 transitions from a closed state to an open state, and the maximum relative difference ΔLmax in the fully open state becomes greater than the minimum relative difference ΔLmin in the fully closed state.

[0100] Here, it is preferable that the maximum relative difference ΔLmax is set based on the state in which the bucket device 10 is fully open as shown in the right diagram of Figure 6, and there is almost no slack in the first winch rope R1. It is also preferable that the minimum relative difference ΔLmin is set based on the state in which the bucket device 10 is fully closed as shown in the left diagram of Figure 6, and there is almost no slack in the second winch rope R2. The maximum relative difference ΔLmax and the minimum relative difference ΔLmin are set in advance by the operator and then stored, for example, in a memory unit 78 built into the controller 70. Alternatively, the maximum relative difference ΔLmax and the minimum relative difference ΔLmin may be stored in a memory unit provided separately from the controller 70. Note that the maximum relative difference ΔLmax corresponds to the first reference value of this disclosure, and the minimum relative difference ΔLmin corresponds to the second reference value of this disclosure.

[0101] The first payout amount Lm of the first winch rope R1 is estimated from the following equation (3). In equation (3), Rm is the design effective radius of the first winch drum DR1. In equation (3), nm is the first rotation amount, which is the number of rotations of the first winch drum DR1 from a reference. In equation (3), once the effective radius Rm is set, the first payout amount Lm of the first winch rope R1 is calculated from the first rotation amount nm of the first winch drum DR1 detected by the first rotation sensor 81. Since the first payout amount Lm is calculated from the first rotation amount nm of the first winch drum DR1 detected by the first rotation sensor 81, the first rotation sensor 81 functions as a first detector for detecting the first payout amount in this disclosure.

[0102] Lm = Rm × nm ... (3)

[0103] The second payout amount La of the second winch rope R2 is estimated from the following equation (4). In equation (4), Ra is the design effective radius of the second winch drum DR2. In equation (4), na is the second rotation amount, which is the number of rotations of the second winch drum DR2 from the reference. In equation (4), once the effective radius Ra is set, the second payout amount La of the second winch rope R2 is calculated from the second rotation amount na of the second winch drum DR2 detected by the second rotation sensor 82. Since the second payout amount La is calculated from the second rotation amount na of the second winch drum DR2 detected by the second rotation sensor 82, the second rotation sensor 82 functions as a second detector for detecting the second payout amount in this disclosure.

[0104] La = Ra × na ···(4)

[0105] As a result, the first payout amount Lm of the first winch rope R1 calculated from equation (3) and the second payout amount La of the second winch rope R2 calculated from equation (4) are applied to equation (2) to calculate the relative difference ΔL. Furthermore, the degree of opening and closing α is calculated by applying the relative difference ΔL to equation (1).

[0106] Figure 7 shows an example of the change in the degree of opening / closing α of the bucket device 10 during operation, calculated by equation (1). In Figure 7, the horizontal axis represents time t [sec] and the vertical axis represents the degree of opening / closing α [%]. A degree of opening / closing α of 100% corresponds to the bucket device 10 being fully open and the relative difference ΔL being the preset maximum relative difference ΔLmax. A degree of opening / closing α of 0% corresponds to the bucket device 10 being fully closed and the relative difference ΔL being the preset minimum relative difference ΔLmin.

[0107] In Figure 7, as the bucket device 10 is opened, that is, as the first winch rope R1 is paid out, the first payout amount Lm increases, and the degree of opening / closing α increases toward 100%. When the degree of opening / closing α reaches 100%, the bucket device 10 is fully open, and the relative difference ΔL becomes the maximum relative difference ΔLmax. If the bucket device 10 is operated further in the opening direction from this state, that is, as the first winch rope R1 is paid out, the first winch rope R1 becomes excessively loose, as shown in the right-hand diagram of Figure 8, resulting in an over-open state where the relative difference ΔL exceeds the maximum relative difference ΔLmax. The over-open state corresponds to the portion in Figure 7 where the degree of opening / closing α is greater than 100%, indicated by the dashed line.

[0108] Furthermore, as the bucket device 10 is closed, that is, as the first winch rope R1 is wound up, the first payout amount Lm decreases, and the degree of opening / closing α decreases toward 0%. When the degree of opening / closing α reaches 0%, the bucket device 10 is in a fully closed state, and the relative difference ΔL becomes the minimum relative difference ΔLmin. If the bucket device 10 is operated further in the closing direction from this state, that is, as the first winch rope R1 is wound up, the second winch rope R2 becomes excessively loose, as shown in the left diagram of Figure 8, resulting in an over-closed state where the relative difference ΔL becomes smaller than the minimum relative difference ΔLmin. The over-closed state corresponds to the portion shown by the dashed line in Figure 7 where the degree of opening / closing α is less than 0%.

[0109] In the over-open state described above, the first winch rope R1 becomes excessively loose, and in the over-closed state described above, the second winch rope R2 becomes excessively loose, which may cause the ropes to become tangled and unruly, which is undesirable. Although the over-open and over-closed states described above can be prevented by visually inspecting the bucket device 10, in some work sites, the bucket device 10 may not be visible due to obstacles or other factors. In this case, the bucket device 10 may unintentionally become over-open or over-closed.

[0110] In response to this, the controller 70 is equipped with an over-opening / closing suppression unit 74. When the bucket device 10 is in an over-open state, the over-opening / closing suppression unit 74 stops the payout of the ropes of the opening / closing drums, which are among the first winch drum DR1 and the second winch drum DR2 that are responsible for opening and closing the bucket device 10, and when the bucket device 10 is in an over-closed state, the over-opening / closing suppression unit 74 stops the winding of the ropes of the opening / closing drums, which are among the first winch drum DR1 and the second winch drum DR2 that are responsible for opening and closing the bucket device 10.

[0111] In this embodiment, the first winch drum DR1 is set as an opening / closing drum responsible for opening and closing the bucket device 10. As a result, the over-opening / closing suppression unit 74 stops paying out the first winch rope R1 from the first winch drum DR1 when the bucket device 10 is in an over-open state. Also, the over-opening / closing suppression unit 74 stops winding up the first winch rope R1 from the first winch drum DR1 when the bucket device 10 is in an over-closed state.

[0112] Furthermore, the open / closed state determination unit 73 has the function of determining whether the bucket device 10 is in an over-open state or an over-closed state. The open / closed state determination unit 73 makes the determination based on the relative difference ΔL, which is calculated as it occurs, the maximum relative difference ΔLmax, and the minimum relative difference ΔLmin. Specifically, if the relative difference ΔL is greater than the maximum relative difference ΔLmax, the open / closed state determination unit 73 determines that the bucket device 10 is in an over-open state, meaning it is being operated in the direction of opening the bucket device 10 further from an open state (fully open state). Also, if the relative difference ΔL is less than the minimum relative difference ΔLmin, the open / closed state determination unit 73 determines that the bucket device 10 is in an over-closed state, meaning it is being operated in the direction of closing the bucket device 10 further from a closed state (fully closed state).

[0113] When the over-opening / closing suppression unit 74 determines that the bucket device 10 is in an over-open state, it performs over-opening suppression control to stop the rotation of the first winch drum DR1 in the unwinding direction. Specifically, the over-opening / closing suppression unit 74 controls the pilot pressure of the first unwinding proportional valve 61A and the secondary pressure (pilot pressure) of the first winding proportional valve 61B to provide an output to the first winch drum DR1 that stops its rotation. More specifically, the over-opening / closing suppression unit 74 may control the pilot pressure of the first unwinding proportional valve 61A and the pilot pressure of the first winding proportional valve 61B to zero and switch the first control valve 32 to the neutral position to stop the rotation of the first winch drum DR1 in the unwinding direction.

[0114] Furthermore, if the over-opening / closing suppression unit 74 determines that the bucket device 10 is in an over-closed state, it performs over-closing suppression control to stop the rotation of the first winch drum DR1 in the winding direction. Specifically, the over-opening / closing suppression unit 74 controls the pilot pressure of the first pay-out proportional valve 61A and the secondary pressure (pilot pressure) of the first winding proportional valve 61B to provide an output that stops the rotation of the first winch drum DR1. Specifically, the over-opening / closing suppression unit 74 may control the pilot pressure of the first pay-out proportional valve 61A and the pilot pressure of the first winding proportional valve 61B to zero, and switch the first control valve 32 to the neutral position to stop the rotation of the first winch drum DR1 in the winding direction.

[0115] As described above, if the bucket device 10 is determined to be in an over-open state, the over-opening / closing suppression unit 74 performs over-opening suppression control, stopping the rotation of the first winch drum DR1 and stopping the payout of the first winch rope R1. As a result, as shown by the solid line in Figure 7, the degree of opening / closing α is prevented from becoming greater than 100%, and the first winch rope R1 is prevented from becoming excessively loose. Similarly, if the bucket device 10 is determined to be in an over-closed state, the over-opening / closing suppression unit 74 performs over-closed suppression control, stopping the rotation of the first winch drum DR1 and stopping the winding of the first winch rope R1. As a result, as shown by the solid line in Figure 7, the degree of opening / closing α is prevented from becoming less than 0%, and the second winch rope R2 is prevented from becoming excessively loose.

[0116] When the opening / closing state determination unit 73 determines that the bucket device 10 is in an over-open or over-closed state, the notification unit 76 activates the alarm device 126, which generates a buzzer sound or voice message. This notifies the operator that the bucket device 10 is in an over-open or over-closed state and prompts the operator to stop operating the bucket device 10 in the opening or closing direction. Furthermore, when the bucket device 10 is determined to be in an over-open or over-closed state, the notification unit 76 may display this on the monitor 120 and prompt the operator to stop operating the bucket device 10 in the opening or closing direction.

[0117] Figure 9 is a flowchart illustrating the control operation of the controller 70, which prevents the bucket device 10 from moving further in the opening direction when it is determined to be in an over-open state, and prevents the bucket device 10 from moving further in the closing direction when it is determined to be in an over-closed state. This flowchart is executed repeatedly while the crane 100 is in operation.

[0118] First, the controller 70 stores the maximum relative difference ΔLmax and minimum relative difference ΔLmin set by the operator in the storage unit 78 (step S10). Next, the controller 70 calculates the current relative difference ΔL from equation (2) (step S20). Then, the controller 70 determines whether the relative difference ΔL calculated in step S20 is greater than the maximum relative difference ΔLmax (step S30).

[0119] If the relative difference ΔL is greater than the maximum relative difference ΔLmax (YES in step S30), the controller 70 provides an output to the first payout proportional valve 61A and the first retraction proportional valve 61B to prevent the first winch drum DR1 from rotating in the payout direction (step S40). This prevents the first winch drum DR1 from rotating in the payout direction. In this case, output in the retraction direction of the first winch drum DR1 is permitted.

[0120] On the other hand, in step S30, if the relative difference ΔL is less than or equal to the maximum relative difference ΔLmax (NO in step S30), the controller 70 determines whether the relative difference ΔL is less than the minimum relative difference ΔLmin (step S50).

[0121] If the relative difference ΔL is less than the minimum relative difference ΔLmin (YES in step S50), the controller 70 provides an output to the first pay-out proportional valve 61A and the first rewind proportional valve 61B to prevent the first winch drum DR1 from rotating in the rewinding direction (step S60). This prevents the first winch drum DR1 from rotating in the rewinding direction. In this case, output in the pay-out direction of the first winch drum DR1 is permitted. If the relative difference ΔL is greater than or equal to the minimum relative difference ΔLmin in step S50 (NO in step S50), the controller 70 terminates control.

[0122] [Setting conditions] Next, the method for setting the maximum relative difference ΔLmax and the minimum relative difference ΔLmin will be described. The controller 70 is equipped with a condition setting unit 77 for setting the maximum relative difference ΔLmax and the minimum relative difference ΔLmin.

[0123] When the condition setting unit 77 receives an ON command signal from the monitor switch 92, for example, to activate the monitor 120, it starts setting the maximum relative difference ΔLmax and the minimum relative difference ΔLmin. The condition setting unit 77 outputs a command to the screen display control unit 75 to start setting the maximum relative difference ΔLmax when the bucket device 10 is at a predetermined lifting height. Upon receiving the above command, the screen display control unit 75 displays an image on the monitor 120 as shown in the left diagram of Figure 10.

[0124] The left side of Figure 10 shows an example of an image displayed on the monitor 120 when setting the maximum relative difference ΔLmax. At the bottom of the monitor 120, text instructions are displayed stating that the bucket device 10 should be opened (to the fully open state) to the extent that the first winch rope R1 and the second winch rope R2 do not slacken. On the left side of the monitor 120, an image diagram shows a preferred example (right side) and an unpredictable example (left side) of the bucket device 10 being in the fully open state. The preferred example is when the bucket device 10 is fully open and the first winch rope R1 and the second winch rope R2 are not slack. The unpredictable example is when the bucket device 10 is fully open and the first winch rope R1 is slack. The left side of Figure 10 also shows the OK button 122, which is selected when the adjustment of the bucket device 10 is complete, and the BACK button 124, which returns to the previous setting.

[0125] The operator operates the first winch operating lever 51A of the first winch operating device 51 and the second winch operating lever 53A of the second winch operating device 53 in accordance with the display on the monitor 120, so that the bucket device 10 is fully open. When the operator confirms that the bucket device 10 is fully open with the first winch rope R1 and the second winch rope R2 not slackening, the operator selects the OK button 122. When the OK button 122 is selected, the condition setting unit 77 obtains the first payout amount Lm of the first winch rope R1 and the second payout amount La of the second winch rope R2 in this state, and calculates the relative difference ΔL from equation (2). Next, the condition setting unit 77 sets the calculated relative difference ΔL to the maximum relative difference ΔLmax and stores the set maximum relative difference ΔLmax in the storage unit 78.

[0126] Next, the condition setting unit 77 starts setting the minimum relative difference ΔLmin. The condition setting unit 77 outputs a command to the screen display control unit 75 to start setting the minimum relative difference ΔLmin when the bucket device 10 is at a predetermined lifting height. Upon receiving the above command, the screen display control unit 75 displays an image on the monitor 120 as shown in the right-hand figure of Figure 10.

[0127] The right-hand diagram in Figure 10 shows an example of an image displayed on the monitor 120 when setting the minimum relative difference ΔLmin. At the bottom of the monitor 120, text instructions are displayed indicating that the bucket device 10 should be closed (fully closed) to the extent that the first winch rope R1 and the second winch rope R2 do not slacken. On the left side of the monitor 120, an image diagram shows a preferred example (right) and an unpredictable example (left) of the bucket device 10 being fully closed. The preferred example is when the bucket device 10 is fully closed and the first winch rope R1 and the second winch rope R2 are not slack. The unpredictable example is when the bucket device 10 is fully closed and the second winch rope R2 is slack. The right-hand diagram in Figure 10 also shows the OK button 122, which is selected when the adjustment of the bucket device 10 is complete, and the BACK button 124, which returns to the previous setting.

[0128] The operator operates the first winch operating lever 51A and the second winch operating lever 53A according to the display on the monitor 120 so that the bucket device 10 is fully closed. When the operator confirms that the bucket device 10 is fully closed with the first winch rope R1 and the second winch rope R2 not slackening, the operator selects the OK button 122. When the OK button 122 is selected, the condition setting unit 77 obtains the first payout amount Lm of the first winch rope R1 and the second payout amount La of the second winch rope R2 in this state and calculates the relative difference ΔL from equation (2). Next, the condition setting unit 77 sets the calculated relative difference ΔL to the minimum relative difference ΔLmin and stores the set minimum relative difference ΔLmin in the storage unit 78.

[0129] Incidentally, the winding layers of the first winch rope R1 in the first winch drum DR1 change according to the first rotation amount nm of the first winch rope R1. In connection with this, the actual effective radius Rm of the first winch drum DR1 changes according to the first rotation amount nm. As a result, there is an error Δrm in the effective radius Rm of the first winch drum DR1. The effective radius Rmer considering the above error Δrm is shown by equation (5) below. For similar reasons, there is also an error Δra in the effective radius Ra of the second winch drum DR2. The effective radius Raer considering the above error Δra is shown by equation (6) below.

[0130] Rmer = Rm + Δrm ... (5) Raer = Ra + Δra ···(6)

[0131] To reduce the effects of these errors Δrm and Δra, the maximum relative difference ΔLmax and minimum relative difference ΔLmin, taking into account the above errors Δrm and Δra, are determined as follows.

[0132] The maximum relative difference ΔLmax is set as the average of the maximum relative difference ΔLmax(Hhigh) set when the bucket device 10 is at its highest lift height Hhigh and the maximum relative difference ΔLmax(Hlow) set when the bucket device 10 is at its lowest lift height Hlow. Specifically, the maximum relative difference ΔLmax is calculated from equation (7) below. The minimum relative difference ΔLmin is set as the average of the minimum relative difference ΔLmin(Hhigh) set when the bucket device 10 is at its highest lift height Hhigh and the minimum relative difference ΔLmin(Hlow) set when the bucket device 10 is at its lowest lift height Hlow. Specifically, the minimum relative difference ΔLmin is calculated from equation (8) below.

[0133] ΔLmax=(ΔLmax(Hhigh)+ΔLmax(Hlow)) / 2 ···(7) ΔLmin=(ΔLmin(Hhigh)+ΔLmin(Hlow)) / 2 ···(8)

[0134] Figure 11 shows the bucket device 10 at its maximum lift height Hhigh and at its minimum lift height Hlow. The maximum lift height Hhigh is the highest position the bucket device 10 can reach. That is, the maximum lift height Hhigh is the value at which the rotation amounts nm and na of each winch drum DR1 and DR2 are minimized, and the distance between the bucket device 10 and the ground G is maximized. The minimum lift height Hlow is the lowest position the bucket device 10 can reach from the ground G. That is, the minimum lift height Hlow is the position at which the rotation amounts nm and na of each winch drum DR1 and DR2 are maximized within the range where the bucket device 10 is away from the ground G. Note that in defining the maximum lift height Hhigh and minimum lift height Hlow of the bucket device 10, the luffing member angle θ (boom angle θ) of the luffing member 104 with respect to the horizontal line is predetermined as a reference angle (for example, 45 degrees).

[0135] As described above, by using the average values ​​of the maximum relative difference ΔLmax and minimum relative difference ΔLmin, which are set at the maximum head Hhigh and minimum head Hlow, the effects of errors Δrm and Δra can be reduced.

[0136] When setting the maximum relative difference ΔLmax and the minimum relative difference ΔLmin, the condition setting unit 77 outputs a command to prompt the operator to move the bucket device 10 to, for example, the maximum lift height Hhigh. Specifically, the condition setting unit 77 issues a command to the screen display control unit 75 to display an instruction on the monitor 120 to move the bucket device 10 to the maximum lift height Hhigh.

[0137] The screen display control unit 75 receives the above command from the condition setting unit 77 and displays an image on the monitor 120 as shown in the left diagram of Figure 12. In the upper right corner of the monitor 120, the instruction to raise the bucket device 10, that is, to move the bucket device 10 to the maximum lifting height Hhigh, is displayed in text. Also, on the left side of the monitor 120, a simplified diagram illustrating the above instruction is displayed. Furthermore, the monitor 120 displays an OK button 122 to be selected when the adjustment of the position of the bucket device 10 is complete, and a BACK button 124 to return to the previous setting.

[0138] The operator raises the bucket device 10 to the maximum lift height Hhigh according to the display on the monitor 120, and then selects the OK button 122. After the OK button 122 is selected, the condition setting unit 77 sets the maximum relative difference ΔLmax(Hhigh) and the minimum relative difference ΔLmin(Hhigh) at the maximum lift height Hhigh.

[0139] Next, the condition setting unit 77 outputs a command to prompt the operator to move the bucket device 10 to the lowest lifting height, Hlow. Specifically, the condition setting unit 77 issues a command to the screen display control unit 75 to display on the monitor 120 an instruction for the operator to move the bucket device 10 to the lowest lifting height, Hlow.

[0140] The screen display control unit 75 receives the above command from the condition setting unit 77 and displays an image on the monitor 120 as shown in the right-hand diagram of Figure 12. In the upper right corner of the monitor 120, a text instruction is displayed to lower the bucket device 10, that is, to move the bucket device 10 to the lowest lifting height, Hlow. Also, on the left side of the monitor 120, a simplified diagram illustrating the above instruction is displayed. Furthermore, the monitor 120 displays an OK button 122 to be selected when the adjustment of the position of the bucket device 10 is complete, and a BACK button 124 to return to the previous setting.

[0141] The operator lowers the bucket device 10 to the minimum lift height Hlow according to the display on the monitor 120, and then selects the OK button 122. After the OK button 122 is selected, the condition setting unit 77 sets the maximum relative difference ΔLmax(Hlow) and the minimum relative difference ΔLmin(Hlow) at the minimum lift height Hlow.

[0142] By performing the above operations, the maximum relative difference ΔLmax(Hhigh) and minimum relative difference ΔLmin(Hhigh) at the highest head height Hhigh, and the maximum relative difference ΔLmax(Hlow) and minimum relative difference ΔLmin(Hlow) at the lowest head height Hlow are obtained. Then, the condition setting unit 77 calculates the maximum relative difference ΔLmax and minimum relative difference ΔLmin from equations (7) and (8), taking into account the errors Δrm and Δra. When calculating the degree of opening α, the influence of the errors Δrm and Δra is reduced by using the above maximum relative difference ΔLmax and minimum relative difference ΔLmin.

[0143] [Determination of the rope responsible for opening and closing] Furthermore, the controller 70 is equipped with an opening / closing rope determination unit 79 that determines whether the winch rope responsible for opening and closing the bucket device 10 is the first winch rope R1 or the second winch rope R2. The opening / closing rope determination unit 79 has the function of determining whether the rope responsible for opening and closing the bucket device 10 is the first winch rope R1 (main winding rope) or the second winch rope R2 (auxiliary winding rope). Depending on how the winch ropes R1 and R2 are connected to the bucket device 10, the first winch rope R1 (main winding rope) may become the rope responsible for opening and closing the bucket device 10, or the second winch rope R2 (auxiliary winding rope) may become the rope responsible for opening and closing the bucket device 10. For example, it is possible that the rope responsible for opening and closing the bucket device 10 may be different from the rope intended by the operator. Therefore, the opening / closing rope determination unit 79 determines the rope responsible for opening and closing the bucket device 10 in accordance with the settings of the maximum relative difference ΔLmax and minimum relative difference ΔLmin described above.

[0144] The opening / closing rope determination unit 79 calculates the first change amount ΔLm and the second change amount ΔLa without changing the lifting height of the bucket device 10. Specifically, the opening / closing rope determination unit 79 calculates, for example, the first change amount ΔLm of the first payout amount Lm of the first winch rope R1 and the second change amount ΔLa of the second payout amount La of the second winch rope R2 when the bucket device 10 is at its lowest lifting height Hlow. The first change amount ΔLm is calculated from the following equation (9). In equation (9), Lmopn is the first payout amount Lm when the bucket device 10 is in the fully open state, and Lmcls is the first payout amount Lm when the bucket device 10 is in the fully closed state. The second change amount ΔLa is calculated from the following equation (10). In equation (10), Laopn is the second payout amount La when the bucket device 10 is fully open, and Lacls is the second payout amount La when the bucket device 10 is fully closed. From equation (9), the first change ΔLm is the difference between the first payout amount Lmopn of the first winch rope R1 when the bucket device 10 is fully open and the first payout amount Lmcls of the first winch rope R1 when the bucket device 10 is fully closed. Also, from equation (10), the second change ΔLa is the difference between the second payout amount Laopn of the second winch rope R2 when the bucket device 10 is fully open and the second payout amount Lacls when the bucket device 10 is fully closed.

[0145] ΔLm = Lmopn - Lmcls ···(9) ΔLa = Laopn - Lacls ···(10)

[0146] The opening / closing rope determination unit 79 calculates the first change amount ΔLm and the second change amount ΔLa, and then determines whether the calculated first change amount ΔLm is greater than the second change amount ΔLa. If the first change amount ΔLm is greater than the second change amount ΔLa, the opening / closing rope determination unit 79 determines that the first winch rope R1 is responsible for opening and closing the bucket device 10, and the second winch rope R2 is responsible for supporting the bucket device 10. On the other hand, if the first change amount ΔLm is less than the second change amount ΔLa, the unit determines that the second winch rope R2 is responsible for opening and closing, and the first winch rope R1 is responsible for supporting the bucket device 10.

[0147] Figure 13 is a flowchart illustrating the control operations performed by the opening / closing rope determination unit 79 when determining which rope is responsible for opening and closing the bucket device 10. The flowchart in Figure 13 is performed when setting initial conditions, for example, when the bucket device 10 is at its lowest lifting height, Hlow.

[0148] First, the opening / closing rope determination unit 79 calculates the change in the first payout amount Lm of the first winch rope R1, ΔLm, from the first payout amount Lmopn of the first winch rope R1 when the bucket device 10 is fully open, and the first payout amount Lmcls of the first winch rope R1 when the bucket device 10 is fully closed (step S110). Next, the opening / closing rope determination unit 79 calculates the change in the second payout amount La of the second winch rope R2, ΔLa, from the second payout amount Laopn of the second winch rope R2 when the bucket device 10 is fully open, and the second payout amount Lacls of the second winch rope R2 when the bucket device 10 is fully closed (step S120). Next, the opening / closing rope determination unit 79 determines whether the change in ΔLm calculated in step S110 is greater than the change in ΔLa calculated in step S120 (step S130). If the change amount ΔLm is greater than the change amount ΔLa (Yes in step S130), the opening / closing rope determination unit 79 determines that the first winch rope R1 is the rope responsible for opening and closing the bucket device 10 (step S140). On the other hand, if the change amount ΔLm is less than the change amount ΔLa (No in step S130), the opening / closing rope determination unit 79 determines that the second winch rope R2 is the rope responsible for opening and closing the bucket device 10 (step S150).

[0149] Based on the flowchart in Figure 13, for example, if the first winch rope R1 is determined to be the rope responsible for opening and closing the bucket device 10, the opening / closing rope determination unit 79 issues a command to the screen display control unit 75 to display an image as shown in Figure 14 on the monitor 120 in order to confirm whether this determination is what the operator intended. The screen display control unit 75 displays an image as shown in Figure 14 on the monitor 120 in accordance with the above command. If the rope responsible for opening and closing the bucket device 10 is determined to be the first winch rope R1, the connection destination of the rope responsible for opening and closing will be displayed as "main winding (first winch rope R1)" as shown in Figure 14. On the other hand, if the rope responsible for opening and closing the bucket device 10 is determined to be the second winch rope R2, the connection destination of the rope responsible for opening and closing will be displayed as "auxiliary winding (second winch rope R2)".

[0150] If the display on monitor 120 matches the operator's intention, the operator selects the OK button 122. On the other hand, if, for example, the display on monitor 120 does not match the operator's intention, the operator selects the BACK button 124 and reconfirms the rope connection destination. This operation prevents the operator from using the wrong rope to open and close the bucket device 10.

[0151] [Second Embodiment] In the first embodiment described above, the degree of opening / closing α of the bucket device 10 was calculated using the relative difference ΔL (=Lm-La) between the first payout amount Lm and the second payout amount La. Alternatively, the opening / closing state determination unit 73 may calculate the degree of opening / closing α using the difference in lifting values ​​ΔLF (=ΔLFm-ΔLFa), which is the difference between the lifting value of the first winch rope R1 (first lifting value LFm) and the lifting value of the second winch rope R2 (second lifting value LFa).

[0152] The lifting height value LF referred to here is different from the lifting height of the bucket device 10 (height from the ground G), and corresponds to the change in lifting height based on a specific state. For example, a specific state may be set to a state where the first winch drum DR1 is at 0 rotations, the second winch drum DR2 is at 0 rotations, and the luffing member angle θ (boom angle θ) of the luffing member 104 with respect to the horizontal line is 45 degrees. The state of "first winch drum DR1 at 0 rotations" is the state in which the first winch rope R1 has been fully extended from the first winch drum DR1. The state of "second winch drum DR2 at 0 rotations" is the state in which the second winch rope R2 has been fully extended from the second winch drum DR2. When the lifting height value of the first winch rope R1 in this specific state is taken as the reference (zero), the first lifting height value LFm is the change in lifting height from that reference. Similarly, when the lifting height of the second winch rope R2 in the aforementioned specific state is taken as the baseline (zero), the second lifting height value LFa is the amount of change in lifting height from that baseline.

[0153] The controller 70 can calculate the first lifting height value LFm of the first winch rope R1 based on the amount of rotation nm of the first winch drum DR1 detected by the first rotation sensor 81 and the luffing member angle θ detected by the luffing member angle detector 83 (see Figure 10). Similarly, the controller 70 can calculate the second lifting height value LFa of the second winch rope R2 based on the amount of rotation na of the second winch drum DR2 detected by the second rotation sensor 82 and the luffing member angle θ. Specifically, it is as follows.

[0154] The first lifting height value LFm of the first winch rope R1 changes not only according to the amount of the first winch rope R1 unfurled from the first winch drum DR1, but also according to the luffing member angle θ of the luffing member 104. Similarly, the second lifting height value LFa of the second winch rope R2 changes not only according to the amount of the second winch rope R2 unfurled from the second winch drum DR2, but also according to the luffing member angle θ of the luffing member 104.

[0155] The controller 70 may pre-store specification data including the length of the luffing member 104, data relating to the relative position of the first winch drum DR1 with respect to a specific part of the luffing member 104 (for example, the base end of the luffing member 104), and data relating to the relative position of the second winch drum DR2 with respect to the said specific part of the luffing member 104. In this case, the controller 70 can calculate a first distance and a second distance that change according to the luffing member angle θ from the geometric positional relationship of the luffing member 104, the first winch drum DR1, and the second winch drum DR2. The first distance is the distance from the first winch drum DR1 to a predetermined first part of the luffing member 104 (for example, the upper end of the luffing member 104). The second distance is the distance from the second winch drum DR2 to a predetermined second part of the luffing member 104 (for example, the upper end of the luffing member 104). Furthermore, the controller 70 may pre-store a relational expression representing the relationship between the luffing member angle θ and the first distance, and a relational expression representing the relationship between the luffing member angle θ and the second distance. In this case, the controller 70 may calculate the first distance and the second distance using the luffing member angle θ detected by the luffing member angle detector 83 and the two relational expressions described above.

[0156] The controller 70 uses information such as specification data including the length of the luffing member 104, data regarding the relative position of the first winch drum DR1 with respect to the specific part of the luffing member 104, and data regarding the relative position of the second winch drum DR2 with respect to the specific part of the luffing member 104, as well as detection results input to the controller 70 from the rotation sensors 81 and 82, and the luffing member angle θ of the luffing member 104 input to the controller 70 from the luffing member angle detector 83, to calculate the first lifting height value LFm of the first winch rope R1 and the second lifting height value LFa of the second winch rope R2, respectively.

[0157] Specifically, for example, the controller 70 may calculate the first lifting height value LFm of the first winch rope R1 based on the change in the first distance ΔL1 for the specific state, the change in the height position of the upper end of the luffing member 104 ΔH1 for the specific state, and the change in the amount of the first winch rope R1 extended ΔR1 for the specific state. The controller 70 may also calculate the first lifting height value LFm of the first winch rope R1 using, for example, the following equation (11).

[0158] First head value LFm = -(ΔL1 + ΔH1 + ΔR1) ... (11)

[0159] Similarly, the controller 70 may calculate the second lifting height value LFab of the second winch rope R2 based on the change in the second distance ΔL2 for the specific state, the change in the height position of the upper end of the luffing member 104 ΔH2 for the specific state, and the change in the amount of the second winch rope R2 extended ΔR2 for the specific state. The controller 70 may calculate the second lifting height value LFab of the second winch rope R2 using, for example, the following equation (12).

[0160] Second head value LFab = -(ΔL2 + ΔH2 + ΔR2) ... (12)

[0161] In the second embodiment, the opening / closing state determination unit 73 calculates the degree of opening / closing α using the following equation (13). In equation (13), the maximum lift value difference ΔLFmax and the minimum lift value difference ΔLFmin are preset values. The maximum lift value difference ΔLFmax is the difference in lift values ​​between the first lift value LFm of the first winch rope R1 and the second lift value LFa of the second winch rope R2 when the bucket device 10 is in the fully open state, and is preset in the same way as the maximum relative difference ΔLmax described above. The minimum lift value difference ΔLFmin is the difference in lift values ​​between the first lift value LFm of the first winch rope R1 and the second lift value LFa of the second winch rope R2 when the bucket device 10 is in the fully closed state, and is preset in the same way as the minimum relative difference ΔLmin described above. The opening / closing state determination unit 73 calculates the degree of opening / closing α of the bucket device 10 by applying the lifting height difference ΔLF, the maximum lifting height difference ΔLFmax, and the minimum lifting height difference ΔLFmin, which are calculated as needed, to equation (13). The maximum lifting height difference ΔLFmax corresponds to the first lifting height reference value of this disclosure, and the minimum lifting height difference ΔLFmin corresponds to the second lifting height reference value of this disclosure.

[0162] α=(ΔLF-ΔLFmin) / (ΔLFmax-ΔLFmin)×100 ···(13)

[0163] Furthermore, in order to improve the calculation accuracy of the degree of opening α, the maximum head difference ΔLFmax may be the average of the maximum head difference ΔLFmax(Hhigh) set when the head of the bucket device 10 is at the highest head height Hhigh and the minimum head difference ΔLFmin(Hlow) set when the head of the bucket device 10 is at the lowest head height Hlow. Similarly, the minimum head difference ΔLFmin may be the average of the minimum head difference ΔLFmin(Hhigh) set when the head of the bucket device 10 is at the highest head height Hhigh and the minimum head difference ΔLFmin(Hlow) set when the head of the bucket device 10 is at the lowest head height Hlow. This further improves the calculation accuracy of the degree of opening α.

[0164] Furthermore, the opening / closing state determination unit 73 determines whether the bucket device 10 is in an over-open state or an over-closed state based on the lifting height difference ΔLF, the maximum lifting height difference ΔLFmax, and the minimum lifting height difference ΔLFmin. Specifically, the opening / closing state determination unit 73 determines that the bucket device 10 is in an over-open state if the lifting height difference ΔLF is greater than the maximum lifting height difference ΔLFmax, and determines that the bucket device 10 is in an over-closed state if the lifting height difference ΔLF is less than the minimum lifting height difference ΔLFmin.

[0165] Furthermore, the opening / closing rope determination unit 79 can determine which of the first winch rope R1 and the second winch rope R2 is responsible for opening and closing the bucket device 10, based on the first lifting height value LFm of the first winch rope R1 and the second lifting height value LFa of the second winch rope R2.

[0166] Specifically, the opening / closing rope determination unit 79 calculates a first lift change amount ΔLFm, which is the difference (=LFmopn-LFmcls) between the first lift value LFmopn of the first winch rope R1 when the bucket device 10 is in a fully open state and the first lift value LFmcls of the first winch rope R1 when the bucket device 10 is in a fully closed state. Furthermore, the opening / closing rope determination unit 79 calculates a second lift change amount ΔLFa, which is the difference (=LFaopn-LFacls) between the second lift value LFabapn of the second winch rope R2 when the bucket device 10 is in a fully open state and the second lift value LFacls of the second winch rope R2 when the bucket device 10 is in a fully closed state. If the calculated first lift change amount ΔLFm is greater than the second lift change amount ΔLFa, the opening / closing rope determination unit 79 determines that the first winch rope R1 is the rope responsible for opening and closing the bucket device 10. Furthermore, the opening / closing rope determination unit 79 determines that the second winch rope R2 is responsible for opening and closing the bucket device 10 if the calculated first lifting height change amount ΔLFm is smaller than the second lifting height change amount ΔLFa. In this way, the bucket device 10 can be over-opened and over-closed, and the rope responsible for opening and closing the bucket device 10 can be determined by the first lifting height value LFm of the first winch rope R1 and the second lifting height value LFa of the second winch rope R2, thereby obtaining the same operation and effects as in the first embodiment.

[0167] [Differentiation] In the above embodiment, the final maximum relative difference ΔLmax and minimum relative difference ΔLmin were determined from the average values ​​of the maximum relative difference ΔLmax and minimum relative difference ΔLmin when the bucket device 10 is at its highest lift height Hhigh and when the bucket device 10 is at its lowest lift height Hlow, but the disclosure is not limited thereto. For example, the maximum relative difference ΔLmax(Hhigh) and minimum relative difference ΔLmin(Hhigh) may be set based on the bucket device 10 being at a predetermined lift height. Similarly, the maximum lift value difference ΔLFmax and minimum lift value difference ΔLFmin may also be set based on the bucket device 10 being at a predetermined lift height.

[0168] In the above embodiment, the rotation of the first winch drum DR1 was stopped based on the pilot pressure output from the first pay-out proportional valve 61A and the pilot pressure output from the first rewind proportional valve 61B, but this disclosure is not limited to the above configuration. For example, the rotation of the first winch drum DR1 may be stopped based on the pilot pressure output from one proportional valve. Similarly, the rotation of the second winch drum DR2 may be stopped based on the pilot pressure output from one proportional valve. In other words, the structure of the first stop device for stopping the rotation of the first winch drum DR1 and the second stop device for stopping the rotation of the second winch drum DR2 may be changed as appropriate.

[0169] In the above embodiment, the bucket device 10 was mounted on a crane 100 as a construction machine, but this disclosure applies to any construction machine that is equipped with a bucket device, and is not limited to cranes.

[0170] In the above embodiment, the storage unit 78 was built into the controller 70, but the storage unit 78 may be located separately from the controller 70.

[0171] In the above embodiment, the control mode of the bucket device 10 was configured to be switchable between assist mode, non-assist mode, synchronized control mode, and non-synchronized control mode. However, this disclosure is not limited to embodiments that have the above control modes. That is, this disclosure is also applicable to conventional cranes that do not have the above control modes.

[0172] In the above embodiment, the bucket control device is provided on the crane 100, but the bucket control device in this disclosure does not necessarily have to be provided on a construction machine such as the crane 100, and may be located at a location away from the construction machine. In this case, the bucket control device is configured to be able to send and receive information between the bucket control device and the construction machine via a network such as the internet or a mobile phone network.

[0173] In the above embodiment, the luffing member 104 shown in Figure 1 is a boom having a lattice structure (lattice boom), but the luffing member may include a boom having a lattice structure and a jib having a lattice structure, or it may be an extendable boom (telescopic boom). The construction machine may be placed on the ground, on a structure, or on a ship. In any of these cases, the lower body of the construction machine may have a crawler running device as shown in Figure 1, a running device including tires, or it may be composed of a structure such as a support platform that cannot move on its own.

[0174] In the above embodiment, both over-opening suppression control and over-closing suppression control were performed, but the present disclosure is not limited thereto. That is, the controller 70 may perform over-opening suppression control but not over-closing suppression control, or vice versa. [Explanation of symbols]

[0175] 10: Bucket device 32: First control valve (first stop device) 33: Second control valve (second stop device) 51: First winch operating device 53: Second winch operating device 61A: First dispensing proportional valve (first proportional valve) 61B: First winding proportional valve (first proportional valve) 63A: Second proportional valve for dispensing (second proportional valve) 63B: Second winding proportional valve (second proportional valve) 70: Controller 73: Open / Close State Determination Unit 74: Over-opening / closing suppression part 76: Hochi Department 78: Storage section 79: Opening / closing rope determination unit 81: First rotation sensor (first detector) 82: Second rotation sensor (second detector) 100: Crane (construction machinery) 126:Alarm device DR1: First winch drum DR2: Second winch drum R1: First winch rope R2: Second winch rope

Claims

1. A bucket control device for a construction machine comprising: a first winch drum for paying out and reeling in a first winch rope; a second winch drum for paying out and reeling in a second winch rope; a bucket device connected to the first and second winch ropes, which can be opened and closed and raised and lowered in accordance with the rotation of the first and second winch drums; a first winch operating device that provides an operation for rotating the first winch drum; and a second winch operating device that provides an operation for rotating the second winch drum, wherein A controller is provided that performs at least one of over-opening suppression control and over-closing suppression control. The over-opening suppression control is a control that stops the controller from paying out the rope of the opening / closing drum, which is the drum responsible for opening and closing the bucket device, among the first and second winch drums, when the bucket device is in an over-open state, being operated in the direction to open the bucket device further from a predetermined open state. The bucket control device is a control that stops the winding of the rope of the opening / closing drum when the bucket device is in an over-closed state, where it is being operated in the direction of closing the bucket device further from a predetermined closed state.

2. In the bucket control device according to claim 1, The aforementioned construction machine, A first detector for detecting a first payout amount, which is the amount of the first winch rope that is paid out, or a first lifting value, which is the lifting value of the first winch rope, A second detector for detecting the second payout amount, which is the amount of the second winch rope that is paid out, or the second lifting value, which is the lifting value of the second winch rope, It comprises a memory unit, The storage unit pre-stores a first reference value which is the difference between the amount of the first winch rope unwound and the amount of the second winch rope unwound when the bucket device is in the predetermined open state, and a second reference value which is the difference between the amount of the first winch rope unwound and the amount of the second winch rope unwound when the bucket device is in the predetermined closed state, or the storage unit pre-stores a first lifting reference value which is the difference between the lifting height of the first winch rope and the lifting height of the second winch rope when the bucket device is in the predetermined open state, and a second lifting reference value which is the difference between the lifting height of the first winch rope and the lifting height of the second winch rope when the bucket device is in the predetermined closed state. A bucket control device wherein the controller determines whether the bucket device is in either the over-open state or the over-closed state based on the relative difference which is the difference between the first discharge amount and the second discharge amount, the first reference value and the second reference value, or the controller determines whether the bucket device is in either the over-open state or the over-closed state based on the lift value difference which is the difference between the first lift value and the second lift value, the first lift reference value and the second lift reference value.

3. In the bucket control device according to claim 2, A bucket control device wherein the controller determines that the bucket device is in the over-open state if the relative difference is greater than the first reference value, and determines that the bucket device is in the over-closed state if the relative difference is less than the second reference value, or the controller determines that the bucket device is in the over-open state if the difference in lifting height is greater than the first lifting height reference value, and determines that the bucket device is in the over-closed state if the difference in lifting height is less than the second lifting height reference value.

4. In the bucket control device according to claim 2, The aforementioned construction machine, A first proportional valve capable of stopping the rotation of the first winch drum, The system further includes a second proportional valve capable of stopping the rotation of the second winch drum, When the controller determines that the bucket device is in the over-open state, it inputs a command to the proportional valve corresponding to the opening / closing drum among the first proportional valve and the second proportional valve to stop the rotation of the opening / closing drum in the unwinding direction. The controller is a bucket control device that, when it is determined that the bucket device is in the over-closed state, inputs a command to the proportional valve corresponding to the opening / closing drum among the first proportional valve and the second proportional valve to stop the rotation of the opening / closing drum in the winding direction.

5. In the bucket control device according to claim 2, The first reference value is set as the average of the first reference value set when the lifting height of the bucket device is at a predetermined maximum lifting height and the first reference value set when the lifting height of the bucket device is at a predetermined minimum lifting height. The second reference value is set as the average of the second reference value set when the lifting height of the bucket device is at the maximum lifting height and the second reference value set when the lifting height of the bucket device is at the minimum lifting height. The first lifting height reference value is set as the average of the first lifting height reference value set when the lifting height of the bucket device is at the maximum lifting height and the first lifting height reference value set when the lifting height of the bucket device is at the minimum lifting height. A bucket control device in which the second lifting reference value is set to the average value of the second lifting reference value set when the lifting height of the bucket device is at the maximum lifting height and the second lifting reference value set when the lifting height of the bucket device is at the minimum lifting height.

6. In the bucket control device according to claim 2, The aforementioned controller, The first change is the difference between the first payout amount of the first winch rope when the bucket device is in the predetermined open state and the first payout amount of the first winch rope when the bucket device is in the predetermined closed state. The second change is calculated as the difference between the second payout amount of the second winch rope when the bucket device is in the predetermined open state and the second payout amount of the second winch rope when the bucket device is in the predetermined closed state. If the first change is greater than the second change, the first winch rope is determined to be the rope responsible for opening and closing the bucket device; if the first change is less than the second change, the second winch rope is determined to be the rope responsible for opening and closing the bucket device; or The aforementioned controller, The first lifting height change is the difference between the first lifting height value of the first winch rope when the bucket device is in the predetermined open state and the first lifting height value of the first winch rope when the bucket device is in the predetermined closed state. The second lifting height change is calculated as the difference between the second lifting height value of the second winch rope when the bucket device is in the predetermined open state and the second lifting height value of the second winch rope when the bucket device is in the predetermined closed state. A bucket control device that determines that the first winch rope is responsible for opening and closing the bucket device when the first change in lifting height is greater than the second change in lifting height, and determines that the second winch rope is responsible for opening and closing the bucket device when the first change in lifting height is less than the second change in lifting height.

7. In the bucket control device according to claim 2, The aforementioned construction machine is further equipped with an alarm device, The controller is a bucket control device that activates the alarm device when the bucket device is determined to be in the over-open state or the over-closed state.

8. A bucket control device for a construction machine comprising: a first winch drum for paying out and reeling in a first winch rope; a second winch drum for paying out and reeling in a second winch rope; a bucket device connected to the first and second winch ropes, which can be opened and closed and raised and lowered in accordance with the rotation of the first and second winch drums; a first winch operating device that provides an operation for rotating the first winch drum; and a second winch operating device that provides an operation for rotating the second winch drum, wherein Equipped with a controller that performs over-opening suppression control, The bucket control device is a bucket control device in which, when the bucket device is in an over-open state, being operated in the direction of further opening the bucket device from a predetermined open state, the controller stops paying out the rope of the opening / closing drum, which is one of the first and second winch drums responsible for opening and closing the bucket device.

9. A bucket control device for a construction machine comprising: a first winch drum for paying out and reeling in a first winch rope; a second winch drum for paying out and reeling in a second winch rope; a bucket device connected to the first and second winch ropes, which can be opened and closed and raised and lowered in accordance with the rotation of the first and second winch drums; a first winch operating device that provides an operation for rotating the first winch drum; and a second winch operating device that provides an operation for rotating the second winch drum, wherein A controller that performs at least one of the over-closing suppression controls, The bucket control device is a control that stops the winding of the rope of the opening / closing drum when the bucket device is in an over-closed state, where it is being operated in the direction of closing the bucket device further from a predetermined closed state.

10. The first winch drum and, The aforementioned second winch drum, The aforementioned bucket device, The first winch operating device and, The second winch operating device and, A construction machine comprising a bucket control device according to any one of claims 1 to 7.

11. A bucket control method for a construction machine comprising: a first winch drum for paying out and reeling in a first winch rope; a second winch drum for paying out and reeling in a second winch rope; a bucket device connected to the first and second winch ropes, which can be opened and closed and raised and lowered in accordance with the rotation of the first and second winch drums; a first winch operating device that provides an operation for rotating the first winch drum; and a second winch operating device that provides an operation for rotating the second winch drum, wherein If the bucket device is in an over-open state, being operated to open it further from a predetermined open state, the controller stops paying out the rope from the opening / closing drum, which is the drum responsible for opening and closing the bucket device, among the first and second winch drums, and A bucket control method comprising at least one of the following: if the bucket device is in an over-closed state, being operated in the direction of closing the bucket device further from a predetermined closed state, the controller stops winding up the rope of the opening / closing drum.

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