Bucket control device, construction machine, and bucket control method

Abstract

This bucket control device (200) is a control device for a construction machine (100) comprising machine bodies (101, 102), a raising / lowering member (104), a first winch drum (DR1), a second winch drum (DR2), and a bucket device (10). The bucket control device (200) comprises a controller (70) that performs a raising / lowering synchronization control for maintaining the open / closed state of buckets (13, 13) by adjusting the amount of unwinding of a first winch rope (R1) and / or the amount of unwinding of a second winch rope (R2) in response to changes in the angle of the raising / lowering member (104) during a raising / lowering operation of the raising / lowering member (104).

Description

Bucket control device, construction machine, and bucket control method

[0001] The present disclosure relates to a technology for a construction machine equipped with a bucket device.

[0002] Conventionally, construction machines equipped with bucket devices are known (for example, Patent Documents 1-2).

[0003] Even when the winch drum for opening and closing the bucket device is stopped, during the raising and lowering operation of the raising and lowering member including the boom, the bucket may change from a closed state to an open state or from an open state to a closed state against the operator's intention.

[0004] Japanese Patent Application Laid-Open No. 2023-23811, Japanese Patent Application Laid-Open No. 2023-23812

[0005] An object of the present disclosure is to provide a technology that can suppress the bucket from changing from a closed state to an open state or from an open state to a closed state against the operator's intention during the raising and lowering operation of the raising and lowering member.

[0006] A bucket control device according to one aspect of the present disclosure is a control device for a construction machine including a machine body, a raising and lowering member that can be raised and lowered with respect to the machine body, a first winch drum that feeds out and winds up a first winch rope hanging down from the raising and lowering member, a second winch drum that is arranged at a position different from the first winch drum and feeds out and winds up a second winch rope hanging down from the raising and lowering member, and a bucket device having a bucket that is connected to the first winch rope and the second winch rope and can be opened and closed according to the operation of the first winch drum and the operation of the second winch drum. The bucket control device includes a controller that performs raising and lowering synchronization control for maintaining the opening and closing state of the bucket by adjusting one or both of the feeding amount of the first winch rope and the feeding amount of the second winch rope according to the angle change of the raising and lowering member during the raising and lowering operation of the raising and lowering member.

[0007] Figure 1 is a side view showing a crane equipped with a bucket control device according to the first, second, or third embodiment of the present disclosure. Figure 2 is a block diagram showing the first winch, second winch, and bucket device and the main components related thereto in the crane according to the first, second, or third embodiment. Figure 3 is a diagram showing the portion of the hydraulic circuit of the crane according to the first, second, or third embodiment that relates to the first winch and the second winch. Figure 4 is a diagram illustrating the opening and closing operation of the bucket device of the crane according to the first, second, or third embodiment. Figure 5 is a diagram illustrating how the bucket changes from a closed state to an open state due to the luffing operation of the luffing member in the crane according to the first or second embodiment. Figure 6 is a diagram illustrating how the bucket changes from an open state to a closed state due to the luffing operation of the luffing member in the crane according to the first or second embodiment. Figure 7 is a diagram illustrating the relationship between a first distance from the first winch drum to a predetermined first part of the luffing member and the luffing angle of the luffing member, and the relationship between a second distance from the second winch drum to a predetermined second part of the luffing member and the luffing angle of the luffing member, in the crane according to the first or second embodiment. Figure 8 is a flowchart illustrating an example of calculation processing performed by the controller of the bucket control device in the crane according to the first or second embodiment. Figure 9 is a block diagram showing the controller of the bucket control device according to the second embodiment and its main related components. Figure 10 is a flowchart illustrating an example of calculation processing performed by the controller according to the second embodiment. Figure 11 is a flowchart illustrating an example of calculation processing performed by the controller according to the second embodiment. Figure 12 is a diagram illustrating an example of a map showing the relationship between the target pilot pressure and the command current value. Figure 13A is a graph illustrating limit control and ground-off control in the crane according to the third embodiment. Figure 13B is a graph illustrating limit control and ground-off control in the crane according to the third embodiment.Figure 13C is a graph illustrating limit control and ground lift control in the crane according to the third embodiment. Figure 14 is a diagram showing an example of a map representing the relationship between the amount of operation for hoisting and the target winding value in the crane according to the third embodiment. Figure 15 is a diagram showing an example of a map representing the relationship between the target pilot pressure and the command current value in the crane according to the third embodiment. Figure 16 is a flowchart illustrating an example of calculation processing performed by the controller of the bucket control device in the crane according to the third embodiment. Figure 17 is a diagram illustrating the switching between normal mode and slow operation mode in the crane according to the third embodiment. Figure 18 is a flowchart illustrating an example of calculation processing performed by the controller in the crane according to the third embodiment. Figure 19 is a block diagram showing the controller of the bucket control device according to a modified example of the third embodiment and the main components related thereto. Figure 20 is a flowchart illustrating an example of calculation processing performed by the controller of the bucket control device according to the modified example. Figure 21 is a graph illustrating ground lift control according to another modified example of the third embodiment. Figure 22 is a graph illustrating ground lift control according to yet another modified example of the third embodiment.

[0008] Embodiments of this disclosure will be described with reference to the drawings.

[0009] This disclosure includes a first technology and a second technology. The first technology mainly includes the first and second embodiments described below. The second technology mainly includes the third embodiment described below. Figures 1 to 4 show the technical content common to the first, second, and third embodiments. Figures 5 to 12 show the technical content relating to the first and second embodiments. Figures 13A to 22 show the technical content relating to the third embodiment.

[0010] [Overview of the Crane] First, an overview of the crane 100 common to the first, second, and third embodiments will be described with reference to Figures 1 to 4.

[0011] Figure 1 shows a crane 100, which is a construction machine according to the first, second, or third 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 plurality of winches arranged on the upper slewing body 102, and a bucket device 10.

[0012] The lower body 101 is a self-propelled lower traveling body equipped with a traveling device such as a crawler traveling device. However, the lower body in this disclosure may be a structure such as a support base that rotatably supports the upper rotating body 102 and is not self-propelled.

[0013] The upper slewing body 102 comprises a slewing frame 103 rotatably attached to the lower body 101, a cabin 114 supported at the front of the slewing frame 103, and a counterweight 115 supported at the rear of the slewing frame 103. The lower body 101 and the upper slewing body 102 are examples of the machine body in this disclosure. However, if the lower body is the structure such as the support base, the machine body in this disclosure may consist of the structure and the upper slewing body.

[0014] The luffing member 104 includes a boom that is supported to be luffable on the slewing frame 103. However, the luffing member in this disclosure may also include a boom and a jib (not shown) that is rotatably supported on the upper end of the boom. The luffing member 104 includes a luffing member body 104A and a plurality of sheaves. The luffing member body 104A is the portion of the upper slewing body 102 that is positioned to protrude from the slewing frame 103 and constitutes the majority of the luffing member 104. In the specific example shown in Figure 1, the luffing member body 104A is composed of a boom having a lattice structure. The plurality of sheaves include a first point sheave 105, a second point sheave 106, a first idler sheave 112, and a second idler sheave 113, which are attached to the upper end of the luffing member body 104A as shown in Figure 1.

[0015] 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 upper end 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 R3 is wrapped around the lower spreader 110 and the upper spreader 109.

[0016] The plurality of winches include a first winch WC1, a second winch WC2, and a luffing winch WC3. The first winch WC1 has a first winch drum DR1 that performs an unwinding operation to unwind a first winch rope R1 (wire rope) and a winding operation to wind up the first winch rope R1. The second winch WC2 has a second winch drum DR2 that performs an unwinding operation to unwind a second winch rope R2 (wire rope) and a winding operation to wind up the second winch rope R2. The luffing winch WC3 has a luffing winch drum DR3 that unwinds and winds up a luffing rope R3 (wire rope).

[0017] The first winch WC1 and the second winch WC2 open and close the bucket device 10 and raise and lower it.

[0018] The luffing rope R3 extends from the luffing winch drum DR3 to the lower spreader 110 and is wrapped around the lower spreader 110 and the upper spreader 109. 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 R3. As this distance decreases or increases, the luffing member 104 reclines. In other words, the luffing winch WC3 can cause the luffing member 104 to recline relative to the upper slewing body 102 by winding in or unwinding the luffing rope R3.

[0019] Figure 2 is a block diagram showing the first winch WC1, the second winch WC2, and the bucket device 10 of the crane 100, and the main components related thereto. Figure 3 is a diagram showing the parts of the hydraulic circuit of the crane 100 that are related to the first winch WC1 and the second winch WC2.

[0020] As shown in Figures 1 to 3, the first winch WC1 includes 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 40, and a reduction gear 47. Similarly, the second winch WC2 includes 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 40, and a reduction gear 47.

[0021] The first winch rope R1 is an opening / 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 for paying out and winding up the first winch rope R1 as an opening / closing rope, and the second winch drum DR2 is a support drum for paying out and winding up the second winch rope R2 as a support rope.

[0022] The first winch drum DR1 is supported by a support member (not shown) on the upper slewing body 102 so as to be rotatable around a horizontal axis, enabling it to pay out and retract the first winch rope R1. The second winch drum DR2 is supported by a support member (not shown) on the upper slewing body 102 so as to be rotatable around a horizontal axis, enabling it to pay out and retract the second winch rope R2.

[0023] The first winch drum DR1 and the second winch drum DR2 are positioned at different locations from each other. Both the first winch drum DR1 and the second winch drum DR2 are located behind the luffing member 104, with the second winch drum DR2 located behind the first winch drum DR1. However, the first winch drum DR1 may be located behind the second winch drum DR2.

[0024] The front-rear direction is based on the orientation of the upper rotating body 102. Specifically, the horizontal direction from the counterweight 115 toward the cabin 114 is forward, and the opposite direction is backward. The left-right direction is the horizontal direction perpendicular to the front-rear direction.

[0025] The first point sheave 105 and the second point sheave 106 are arranged side by side and attached to the upper end of the undulating member 104. The first idler sheave 112 and the second idler sheave 113 are arranged side by side and attached to the upper end of the undulating member 104. The first idler sheave 112 is located behind the first point sheave 105, and the second idler sheave 113 is located behind the second point sheave 106.

[0026] The first winch rope R1 extends from the first winch drum DR1 to the upper end of the luffing member 104, hangs down from the upper end, and is connected to the bucket device 10. Specifically, the first winch rope R1 is supported by the first idler sheave 112 and the first point sheave 105, and hangs down from the first point sheave 105. The second winch rope R2 extends from the second winch drum DR2 to the upper end of the luffing member 104, hangs down from the upper end, and is connected to the bucket device 10. Specifically, the second winch rope R2 is supported by the second idler sheave 113 and the second point sheave 106, and hangs down from the second point sheave 106. The lower ends (tips) of the first winch rope R1 and the second winch rope R2 are each connected to the bucket device 10.

[0027] The bucket device 10 is a work device known as a clamshell bucket. The bucket device 10 has buckets 13, 13 to which the first winch rope R1 and the second winch rope R2 are connected, and which can be opened and closed and raised and lowered in accordance with the operation of the first winch drum DR1 and the second winch drum DR2.

[0028] Specifically, as shown in Figure 4, 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. The right side of Figure 4 shows the open state in which the buckets 13, 13 of the bucket device 10 are open, and the left side of Figure 4 shows the closed state in which the buckets 13, 13 of the bucket device 10 are closed.

[0029] 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.

[0030] 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 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.

[0031] The pair of buckets 13, 13 have a storage space capable of accommodating materials to be transported, 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 (the closed state) and a state where the lower ends of the buckets 13, 13 are separated horizontally (the 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.

[0032] The first winch rope R1 (the opening / closing rope) is wrapped around the lower sheave 14 and the upper sheave 15, and the tip of the first winch rope R1 is fixed to either the upper member 11 or the lower member 16. The tip of the second winch rope R2 (the support rope) is fixed to the upper member 11.

[0033] The first winch motor 34 and the second winch motor 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., either the unwinding direction or 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., either the unwinding direction or 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).

[0034] 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.

[0035] The first clutch brake 40 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 unwound from the first winch drum DR1 by the weight of the bucket device 10. The first clutch brake 40 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.

[0036] Similarly, the second clutch brake 40 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 40 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.

[0037] The aforementioned connection state allows the first winch rope R1 and the second winch rope R2 to be unwound and wound up by the driving force of the first winch motor 34 and the second winch motor 35. That is, when the first winch motor 34 and the second winch motor 35 are driven in the aforementioned connection state, the driving force of the first winch motor 34 and the second winch motor 35 is transmitted to the first winch drum DR1 and the second winch drum DR2, respectively, via the reduction gears 47, 47. When the first winch drum DR1 and the second winch drum DR2 rotate, the first winch rope R1 and the second winch rope R2 are unwound or wound up.

[0038] The free state is a state in which the first winch rope R1 and the second winch rope R2 can be unfurled from the first winch drum DR1 and the second winch drum DR2 by the tension of the first winch rope R1 and the second winch rope 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 winch rope R1 and the second winch rope R2 can be unfurled from the first winch drum DR1 and the second winch drum DR2 without rotating the first winch motor 34 and the second winch motor 35 in the unfurling direction of the first winch rope R1 and the second winch rope R2.

[0039] Furthermore, the first clutch brake 40 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 40 can apply a second braking force to the second winch drum DR2, that is, it can brake the second winch drum DR2.

[0040] 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 unwind 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 unwind the second winch rope R2 from the second winch drum DR2. Therefore, the first braking force of the first clutch brake 40 and the second braking force of the second clutch brake 40 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.

[0041] Each of the first clutch brake 40 and the second clutch brake 40 is a so-called wet brake and comprises 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 lubricating oil.

[0042] 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, each of the first clutch brake 40 and the second clutch brake 40 enters the free state, thereby allowing the bucket device 10 to descend (free fall) by its own weight. Conversely, when the multiple brake discs 41 enter the contact state, each of the first clutch brake 40 and the second clutch brake 40 enters the connected state.

[0043] More specifically, each of the first clutch brake 40 and the second clutch brake 40 is equipped with a spring 46, and each of the first clutch brake 40 and the second clutch brake 40 has a pair of oil chambers 43 and 44 formed therein, and the piston 42 has a flange 45 that separates the pair of oil chambers 43 and 44. When the hydraulic pressure applied to the pair of oil chambers 43 and 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 or equal to a predetermined amount than the hydraulic pressure applied to the other oil chamber 43, the multiple brake discs 41 move away from each other.

[0044] The crane 100 includes a first control valve 32, a second control valve 33, a first payout proportional valve 61A, a first take-in proportional valve 61B, a second payout proportional valve 63A, a second take-in proportional valve 63B, a first brake proportional valve 62, a second brake proportional valve 64, and a plurality of operating devices. Each of the proportional valves 61A, 61B, 62, 63A, 63B, 64 is an electromagnetic proportional pressure reducing valve.

[0045] 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 control valve 32 and the second control valve 33 is constituted by a hydraulic pilot switching valve having a pair of pilot ports.

[0046] The pair of pilot ports are an unwinding pilot port and a winding pilot port. When no pilot pressure is applied to either pilot port, the first control valve 32 and the second control valve 33 are held in a neutral position, shutting off the winch motor corresponding to the control valve (hereinafter referred to as the "corresponding winch motor") from the hydraulic pump 31. When pilot pressure is applied to the unwinding pilot port, the first control valve 32 and the second control valve 33 open 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. When pilot pressure is applied to the winding pilot port, the first control valve 32 and the second control valve 33 open to form an oil passage for rotating the corresponding winch motor in the winding direction, that is, an oil passage for supplying hydraulic fluid from the hydraulic pump 31 to the corresponding winch motor in the winding direction. The opening degrees of the first control valve 32 and the second control valve 33 increase as the pilot pressure increases, so as to allow the hydraulic fluid to flow at a flow rate corresponding to the pilot pressure input to the control valve.

[0047] 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 a controller 70 (described later), 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.

[0048] Similarly, the second payout proportional valve 63A is interposed between a pilot hydraulic pressure source (not shown) and the payout pilot port of the second control valve 33. As a second payout command, which is an electric signal, is input from the controller 70 to the proportional valve 63A, the proportional valve 63A opens to allow a pilot pressure proportional to the second payout command to be input to the payout pilot port. The second take-up proportional valve 63B is interposed between the pilot hydraulic pressure source and the take-up pilot port of the second control valve 33. As a second take-up command, which is an electric signal, is input from the controller 70 to the proportional valve 63B, the proportional valve 63B opens to allow a pilot pressure proportional to the second take-up command to be input to the take-up pilot port.

[0049] The first braking proportional valve 62 is interposed between the pilot hydraulic pressure source P and the first clutch brake 40. As a first braking command, which is an electric signal, is input from the controller 70 to the proportional valve 62, the proportional valve 62 opens to allow a hydraulic pressure (first pilot pressure) proportional to the first braking command to be input to the oil chamber 43 of the first clutch brake 40. Thereby, the first braking proportional valve 62 can switch the state of the first clutch brake 40 between the free state and the connected state.

[0050] Similarly, the second braking proportional valve 64 is interposed between the pilot hydraulic pressure source P and the second clutch brake 40. As a second braking command, which is an electric signal, is input from the controller 70 to the proportional valve 64, the proportional valve 64 opens to allow a hydraulic pressure (second pilot pressure) proportional to the second braking command to be input to the oil chamber 43 of the second clutch brake 40. Thereby, the second braking proportional valve 64 can switch the state of the second clutch brake 40 between the free state and the connected state.

[0051] As shown in Figures 1 to 3, the multiple operating devices include a first winch operating device 51, a second winch operating device 53, a first brake operating device 52, a second brake operating device 54, and a luffing operating device 55 (see Figure 1).

[0052] As shown in Figure 2, the first winch operating device 51 includes a first winch operating lever 51A and a first lever input detector 51B. The second winch operating device 53 includes a second winch operating lever 53A and a second lever input detector 53B. The first brake operating device 52 includes a first brake operating pedal 52A and a first pedal input detector 52B. The second brake operating device 54 includes a second brake operating pedal 54A and a second pedal input detector 54B. As shown in Figure 1, the luffing operating device 55 includes a luffing operating lever 55A and a luffing lever input detector 55B.

[0053] The first winch operating lever 51A is an operating member to which an operator performs a first lever operation to specify the rotation direction and rotation 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, as the first lever operation.

[0054] The first lever input detector 51B detects the amount of the first lever operation (extend or retract operation) applied to the first winch operating lever 51A, and inputs the detection result to the controller 70.

[0055] Similarly, the second winch operating lever 53A is an operating member to which a second lever operation is performed by an operator to specify the rotation direction and rotation 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, as the second lever operation.

[0056] The second lever input detector 53B detects the amount of operation of the second lever (extend or retract) applied to the second winch operating lever 53A, and inputs the detection result to the controller 70.

[0057] The first brake operation pedal 52A is an operating member to which an operator performs a first pedal operation to specify a first braking force on the first winch drum DR1. The first pedal input detector 52B detects the amount of the first pedal operation applied to the first brake operation pedal 52A and inputs the detection result to the controller 70.

[0058] The second brake operation pedal 54A is an operating member to which an operator performs a second pedal operation to specify a second braking force on the second winch drum DR2. The second pedal input detector 54B detects the amount of the second pedal operation applied to the second brake operation pedal 54A and inputs the detection result to the controller 70.

[0059] The luffing lever 55A is an operating member that allows an operator to perform luffing operations to specify the rotation direction and rotation speed of the luffing winch drum DR3. Specifically, the luffing lever 55A is provided with either a lowering operation to rotate the luffing winch drum DR3 in the unwinding direction to unwind the luffing rope R3, or an uprighting operation to rotate the luffing winch drum DR3 in the winding direction to wind up the luffing rope R3.

[0060] The luffing lever input detector 55B detects the amount of luffing operation (lowering operation or raising operation) applied to the luffing operation lever 55A, and inputs the detection result to the controller 70.

[0061] When the luffing lever 55A is lowered, hydraulic fluid discharged from the hydraulic pump 31 is supplied to the luffing motor, which is a hydraulic motor not shown in the figure. As a result, the luffing member 104 performs a lowering operation in which the luffing angle θ, described later, gradually decreases. When the luffing lever 55A is raised, hydraulic fluid discharged from the hydraulic pump 31 is supplied to the luffing motor. As a result, the luffing member 104 performs a raised operation in which the luffing angle θ gradually increases. The luffing operation includes the lowering operation and the raised operation.

[0062] The crane 100 includes a luffing member angle detector 22, a first drum rotation detector 81, and a second drum rotation detector 82.

[0063] The luffing member angle detector 22 detects the luffing angle θ of the luffing member 104 and inputs the detection result to the controller 70. In this embodiment, the luffing member angle detector 22 detects the boom angle, which is the angle of the boom of the luffing member 104, as the luffing angle θ. The luffing angle θ is the angle of the luffing member 104 with respect to a predetermined reference. The reference may be, for example, a horizontal line or a horizontal plane, another straight line or another plane, the upper slewing body 102, or the lower body 101.

[0064] The first drum rotation detector 81 detects a first rotation amount ωm, which is the amount of rotation of the first winch drum DR1, and inputs the detection result to the controller 70. The second drum rotation detector 82 detects a second rotation amount ωa, which is the amount of rotation of the second winch drum DR2, and inputs the detection result to the controller 70.

[0065] [First Embodiment] Next, a bucket control device 200 according to the first embodiment will be described.

[0066] The bucket control device 200 is a control device for the crane 100. In the first embodiment, the bucket control device 200 is provided on the crane 100.

[0067] The bucket control device 200 includes a controller 70. The controller 70 performs luffing synchronization control to maintain the open and closed states of the buckets 13, 13 by adjusting one or both of the payout amounts of the first winch rope R1 and the second winch rope R2 in accordance with the angle change of the luffing member 104 during the luffing operation of the luffing member 104.Therefore, it is suppressed that the buckets 13, 13 will change from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member 104.

[0068] The controller 70 comprises a computer having an arithmetic processing unit and memory. The elevation synchronization control by the controller 70 is achieved by the arithmetic processing unit executing a control program stored in the memory.

[0069] The controller 70 can calculate the amount of the first winch rope R1 to be unwound based on a first rotation amount ωm input from the first drum rotation detector 81. The controller 70 can also calculate the amount of the second winch rope R2 to be unwound based on a second rotation amount ωa input from the second drum rotation detector 82.

[0070] Figure 5 is a diagram illustrating how the buckets 13, 13 change from a closed state to an open state during the luffing operation of the luffing member 104 when the luffing synchronization control is not performed. Figure 6 is a diagram illustrating how the buckets 13, 13 change from an open state to a closed state due to the luffing operation of the luffing member 104 when the luffing synchronization control is not performed.

[0071] If the luffing synchronization control described above is not performed, even if the first winch drum DR1 and the second winch drum DR2 for opening and closing the buckets 13, 13 are stopped, a difference will occur between the change in the length of the first winch rope R1 from the first winch drum DR1 to the bucket device 10 during luffing operation and the change in the length of the second winch rope R2 from the second winch drum DR2 to the bucket device 10 during luffing operation, due to the difference in the relative position of the first winch drum DR1 with respect to the luffing member 104 and the relative position of the second winch drum DR2 with respect to the luffing member 104. For this reason, as shown in Figure 5, the bucket may change from a closed state (left diagram in Figure 5) to an open state (right diagram in Figure 5) during luffing operation, or the bucket may change from an open state (left diagram in Figure 6) to a closed state (right diagram in Figure 6).

[0072] If the luffing synchronization control described above is not performed, as shown in the right diagram of Figure 5, the portion of the second winch rope R2 hanging down from the upper end of the luffing member 104 remains taut during the luffing motion, while the portion of the first winch rope R1 hanging down from the upper end of the luffing member 104 becomes loose during the luffing motion. As a result, the buckets 13, 13 change from a closed state to an open state.

[0073] If the luffing synchronization control described above is not performed, as shown in the right diagram of Figure 6, the portion of the first winch rope R1 hanging down from the upper end of the luffing member 104 remains taut during the luffing operation, while the portion of the second winch rope R2 hanging down from the upper end of the luffing member 104 becomes loose during the luffing operation. As a result, the buckets 13, 13 of the bucket device 10 will change from an open state to a closed state.

[0074] In the bucket control device 200 according to the first embodiment, the controller 70 performs the luffing synchronization control, so that the buckets 13, 13 do not change from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member 104.

[0075] Figure 7 is a diagram illustrating the relationship between the first distance Ltop-m(θ), which is the distance from the first winch drum DR1 to a predetermined first portion P1 of the luffing member 104, and the luffing angle θ of the luffing member 104, and the relationship between the second distance Ltop-a(θ), which is the distance from the second winch drum DR2 to a predetermined second portion P2 of the luffing member 104, and the luffing angle θ of the luffing member 104.

[0076] In the first embodiment, the first part P1 is the upper end of the luffing member 104, and the second part P2 is the upper end of the luffing member 104. The first part P1 may be the part of the luffing member 104 that supports the first winch rope R1. Specifically, the first part P1 may be a first idler sheave 112 or a first point sheave 105 for supporting the first winch rope R1. The second part P2 may be the part of the luffing member 104 that supports the second winch rope R2. Specifically, the second part P2 may be a second idler sheave 113 or a second point sheave 106 for supporting the second winch rope R2.

[0077] In the luffing synchronization control, the controller 70 calculates a first distance change amount ΔLtop-m and a second distance change amount ΔLtop-a, and adjusts either or both the payout amount of the first winch rope R1 and the payout amount of the second winch rope R2 based on the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a. The first distance change amount ΔLtop-m is the amount of change in the first distance Ltop-m(θ) that changes in accordance with the angle change of the luffing member 104. The second distance change amount ΔLtop-a is the amount of change in the second distance Ltop-a(θ) that changes in accordance with the angle change of the luffing member 104.

[0078] 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 Ltop-m(θ) and a second distance Ltop-a(θ) that change according to the luffing angle θ, based on the geometric positional relationship of the luffing member 104, the first winch drum DR1, and the second winch drum DR2. The controller 70 may also pre-store relational expressions representing the relationship between the luffing angle θ and the first distance Ltop-m(θ), and relational expressions representing the relationship between the luffing angle θ and the second distance Ltop-a(θ). In this case, the controller 70 may calculate the first distance Ltop-m(θ) and the second distance Ltop-a(θ) using the elevation angle θ detected by the elevation member angle detector 22 and the two relational expressions described above.

[0079] If the aforementioned luffing synchronization control is not performed, the relative position of the first winch drum DR1 with respect to the luffing member 104 and the relative position of the second winch drum DR2 with respect to the luffing member 104 will be different. As a result, a difference will occur between the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a during the luffing operation of the luffing member 104, which may result in a change in the opening and closing state of the bucket. Specifically, this is as follows:

[0080] For the sake of explanation, the length of the portion of the first winch rope R1 from the upper end of the luffing member 104 to the bucket device 10 will be referred to as the first hanging portion length, and the length of the portion of the second winch rope R2 from the upper end of the luffing member 104 to the bucket device 10 will be referred to as the second hanging portion length.

[0081] When the elevation angle θ decreases and the second distance change ΔLtop-a becomes larger than the first distance change ΔLtop-m, the decrease in the length of the second hanging portion of the second winch rope R2 becomes larger than the decrease in the length of the first hanging portion of the first winch rope R1. In this case, even if the buckets 13, 13 were closed when the elevation angle θ was θ1, as shown in the left diagram of Figure 5, when the elevation angle θ becomes θ2 and the decrease in the length of the second hanging portion becomes larger than the decrease in the length of the first hanging portion, the second winch rope R2 may become taut while the first winch rope R1 becomes slack, as shown in the right diagram of Figure 5.

[0082] On the other hand, in the bucket control device 200 according to the first embodiment, the controller 70 adjusts either or both of the payout amount of the first winch rope R1 and the payout amount of the second winch rope R2 based on the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a, thereby maintaining the open and closed states of the buckets 13, 13. This prevents the buckets 13, 13 from changing from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member 104. In addition, it prevents slack from occurring in the first winch rope R1 or the second winch rope R2 during the luffing operation of the luffing member 104.

[0083] In the luffing synchronization control, the controller 70 may adjust one or both of the payout amounts of the first winch rope R1 and the second winch rope R2 so that the payout amount deviation, which is the difference between the change in the payout amount of the first winch rope R1 and the change in the payout amount of the second winch rope R2, matches the distance change amount deviation er, which is the difference between the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a. As the distance change amount deviation er increases, the degree of change in the opening and closing state of the buckets 13, 13 also increases, but by adjusting one or both of the payout amounts of the first winch rope R1 and the second winch rope R2 to match the payout amount deviation er, the maintenance of the opening and closing state of the buckets 13, 13 becomes more reliable.

[0084] As shown in Figure 7, the first distance change ΔLtop-m, which is the amount of change in the first distance Ltop-m when the elevation angle θ of the elevation member 104 changes from θ1 to θ2, is expressed by the following equation (1). The second distance change ΔLtop-a, which is the amount of change in the second distance Ltop-a when the elevation angle θ of the elevation member 104 changes from θ1 to θ2, is expressed by the following equation (2).

[0085]

[0086]

[0087] The first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a each change in accordance with the angle change of the undulating member 104.

[0088] The controller 70 may calculate the correction amount necessary for luffing synchronization control to maintain the open / closed state of the bucket 13 during the luffing operation of the luffing member 104, based on the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a. The controller 70 can perform luffing synchronization control that takes the correction amount into consideration by sequentially calculating the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a. Specifically, it is as follows.

[0089] [When θ1 > θ2] In the specific example shown in Figure 7, as described above, the first winch drum DR1 and the second winch drum DR2 are located behind the luffing member 104, and the second winch drum DR2 is located behind the first winch drum DR1. Therefore, as shown in Figure 7, when angle θ1 is greater than angle θ2 (θ1 > θ2), when the luffing member 104 performs the aforementioned tilting operation and the luffing angle θ decreases from θ1 to θ2, the first distance Ltop-m and the second distance Ltop-a each increase, and the second distance change amount ΔLtop-a (i.e., the increase in the second distance Ltop-a) becomes greater than the first distance change amount ΔLtop-m (i.e., the increase in the first distance Ltop-m). In this case, the controller 70 can calculate the distance change deviation er, which is the difference between the first distance change ΔLtop-m and the second distance change ΔLtop-a, using, for example, the following equation (3). The distance change deviation er is an example of the correction amount.

[0090] er=ΔLtop-m-ΔLtop-a (3)

[0091] When the luffing angle θ decreases from θ1 to θ2, the controller 70 adjusts either or both of the payout amounts of the first winch rope R1 and the second winch rope R2 so that the change in the payout amount of the second winch rope R2 is greater than the change in the payout amount of the first winch rope R1 by the absolute value of the distance change deviation er |er|. This ensures that even when the luffing angle θ decreases from θ1 to θ2, the buckets 13, 13 remain closed during the luffing operation of the luffing member 104. Specifically, when the luffing angle θ decreases from θ1 to θ2, the controller 70 may perform the following first open / closed state maintenance control, second open / closed state maintenance control, or third open / closed state maintenance control.

[0092] In the first open / closed state maintenance control, when the elevation angle θ decreases from θ1 to θ2, the controller 70 reduces the amount of the first winch rope R1 paid out, while keeping the amount of the second winch rope R2 paid out unchanged. That is, when the elevation angle θ decreases from θ1 to θ2, the controller 70 controls the operation of the first winch drum DR1 so that the first winch rope R1 is wound up by an absolute value |er|, and does not operate the second winch drum DR2.

[0093] In the second open / closed state maintenance control, when the elevation angle θ decreases from θ1 to θ2, the controller 70 increases the amount of the second winch rope R2 paid out, while keeping the amount of the first winch rope R1 paid out unchanged. That is, when the elevation angle θ decreases from θ1 to θ2, the controller 70 controls the operation of the second winch drum DR2 so that the second winch rope R2 is paid out by an absolute value |er|, and does not operate the first winch drum DR1.

[0094] In the third open / closed state maintenance control, the controller 70 adjusts both the payout amount of the first winch rope R1 and the payout amount of the second winch rope R2 so that when the elevation angle θ decreases from θ1 to θ2, the change in the payout amount of the second winch rope R2 is greater than the change in the payout amount of the first winch rope R1 by an absolute value |er|.

[0095] Furthermore, when the first winch rope R1 is unwound from the first winch drum DR1, the change in the amount of the first winch rope R1 unwound is a positive value, and when the first winch rope R1 is wound onto the first winch drum DR1, the change in the amount of the first winch rope R1 unwound is a negative value. Similarly, when the second winch rope R2 is unwound from the second winch drum DR2, the change in the amount of the second winch rope R2 unwound is a positive value, and when the second winch rope R2 is wound onto the second winch drum DR2, the change in the amount of the second winch rope R2 unwound is a negative value.

[0096] [When θ1 < θ2] Although not shown in the diagram, when angle θ1 is smaller than angle θ2 (θ1 < θ2), when the luffing member 104 performs the uprighting operation and the luffing angle θ increases from θ1 to θ2, the first distance Ltop-m and the second distance Ltop-a each decrease, and the second distance change amount ΔLtop-a (i.e., the decrease in the second distance Ltop-a) becomes larger than the first distance change amount ΔLtop-m (i.e., the decrease in the first distance Ltop-m). In this case, the controller 70 can calculate the distance change amount deviation er, which is the difference between the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a, using the following equation (3) in the same manner as above.

[0097] er=ΔLtop-m-ΔLtop-a (3)

[0098] When the luffing angle θ increases from θ1 to θ2, the controller 70 adjusts either or both of the payout amounts of the first winch rope R1 and the second winch rope R2 so that the change in the payout amount of the second winch rope R2 is less than the change in the payout amount of the first winch rope R1 by the absolute value of the distance change deviation er |er|. As a result, even when the luffing angle θ increases from θ1 to θ2, the buckets 13, 13 remain open during the luffing operation of the luffing member 104. Specifically, when the luffing angle θ increases from θ1 to θ2, the controller 70 may perform the following fourth open / closed state maintenance control, fifth open / closed state maintenance control, or sixth open / closed state maintenance control.

[0099] In the fourth open / closed state maintenance control, when the elevation angle θ increases from θ1 to θ2, the controller 70 increases the amount of the first winch rope R1 paid out, while keeping the amount of the second winch rope R2 paid out unchanged. That is, when the elevation angle θ increases from θ1 to θ2, the controller 70 controls the operation of the first winch drum DR1 so that the first winch rope R1 is paid out by an absolute value |er|, and does not operate the second winch drum DR2.

[0100] In the fifth open / closed state maintenance control, when the elevation angle θ increases from θ1 to θ2, the controller 70 reduces the amount of the second winch rope R2 paid out while keeping the amount of the first winch rope R1 unchanged. That is, when the elevation angle θ increases from θ1 to θ2, the controller 70 controls the operation of the second winch drum DR2 so that the second winch rope R2 is wound up by an absolute value |er|, and does not operate the first winch drum DR1.

[0101] In the sixth open / closed state maintenance control, the controller 70 adjusts both the payout amount of the first winch rope R1 and the payout amount of the second winch rope R2 so that when the elevation angle θ increases from θ1 to θ2, the change in the payout amount of the second winch rope R2 is less than the change in the payout amount of the first winch rope R1 by an absolute value |er|.

[0102] The controller 70 may perform the luffing synchronization control when the luffing operation lever 55A of the luffing operation device 55 receives the luffing operation. In this case, the controller 70 can perform the luffing synchronization control at an appropriate timing based on the luffing operation.

[0103] Specifically, the controller 70 may perform the luffing synchronization control when a detection result indicating that the luffing operation lever 55A has received the luffing operation is input to the controller 70 from the luffing lever input detector 55B.

[0104] More specifically, if the controller 70 receives a detection result from the luffing lever input detector 55B indicating that the luffing lever 55A has been lowered, it may perform the first open / closed state maintenance control, the second open / closed state maintenance control, or the third open / closed state maintenance control in the luffing synchronization control. Alternatively, if the controller 70 receives a detection result from the luffing lever input detector 55B indicating that the luffing lever 55A has been raised, it may perform the fourth open / closed state maintenance control, the fifth open / closed state maintenance control, or the sixth open / closed state maintenance control in the luffing synchronization control.

[0105] Figure 8 is a flowchart showing an example of the calculation process for the elevation synchronization control performed by the controller 70.

[0106] In step S11, the controller 70 determines whether or not predetermined power synchronization mode conditions are met. The power synchronization mode conditions are conditions for determining whether or not to set the control mode of the crane 100 to power synchronization mode. When the control mode of the crane 100 is set to power synchronization mode, the controller 70 performs the luffing synchronization control.

[0107] If the power synchronization mode condition is met (YES in step S11), the controller 70 sets the control mode of the crane 100 to the power synchronization mode (step S12) and performs luffing synchronization control, including the processing in steps S13 to S15. On the other hand, if the power synchronization mode condition is not met (NO in step S11), the controller 70 does not perform the luffing synchronization control.

[0108] The power synchronization mode condition may be, for example, the condition that the luffing operation lever 55A is being operated (Condition 1). Alternatively, the power synchronization mode condition may be, for example, the condition that the luffing operation lever 55A is being operated with the assist mode switch 91 (described later) turned ON (Condition 2). Alternatively, the power synchronization mode condition may be, for example, the condition that the luffing operation lever 55A is being operated with the opening / closing mode switch 90 (described later) turned OFF (Condition 3). Alternatively, the power synchronization mode condition may be, for example, the condition that the luffing operation lever 55A is being operated with the opening / closing mode switch 90 turned OFF and the assist mode switch 91 turned ON (Condition 4). However, the power synchronization mode condition may include other conditions in addition to Condition 1, Condition 2, Condition 3, or Condition 4. The condition that the luffing operation lever 55A is being operated, which is included in Condition 1, Condition 2, Condition 3, and Condition 4, is a condition for determining whether the luffing member 104 is in the process of luffing.

[0109] In step S13, the controller 70 calculates the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a.

[0110] In step S14, the controller 70 calculates a correction amount (e.g., distance change deviation er) to maintain the open / closed state of the buckets 13, 13 based on the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a.

[0111] In step S15, the controller 70 maintains the open / closed state of the buckets 13, 13 by adjusting one or both of the payout amounts of the first winch rope R1 and the second winch rope R2 based on the calculated correction amount. The controller 70 repeats the process from step S11 onwards.

[0112] [Second Embodiment] Figure 9 is a block diagram showing the controller 70 of the bucket control device 200 according to the second embodiment of this disclosure and the main components related thereto. The basic configuration of the bucket control device 200 and the crane 100 according to the second embodiment is the same as the configuration of the bucket control device 200 and the crane 100 according to the first embodiment, which were described with reference to Figures 1 to 8. The bucket control device 200 according to the second embodiment differs from the first embodiment in that it selects one mode from a predetermined number of modes based on predetermined conditions and sets the control mode of the crane 100 to the selected mode. Accordingly, in the following, we will mainly describe the configuration of the bucket control device 200 and the crane 100 according to the second embodiment that differs from the first embodiment, and will omit the description of the configuration that is the same as the first embodiment.

[0113] As shown in Figure 9, the crane 100 according to the second embodiment includes an operator setting device 21, a first drum rotation detector 81, a second drum rotation detector 82, a luffing member angle detector 22, at least one mode switch, lever input detectors 51B, 53B, 55B, pedal input detectors 52B, 54B, a load value detector 94, and a setting memory device 95 (previous setting memory device).

[0114] The first drum rotation detector 81, the second drum rotation detector 82, the undulation member angle detector 22, the lever input detectors 51B, 53B, 55B, and the pedal input detectors 52B, 54B are the same as those described above for the first embodiment.

[0115] The operator setting device 21 is an input device for the operator to input various settings necessary for the operation of the crane 100 according to the second embodiment. The operator setting device 21 receives input from the operator for the various settings. The operator setting device 21 may be located, for example, inside the cabin 114. The operator setting device 21 may include, for example, a monitor touch panel. The various settings may include, for example, specification data for the main components constituting the construction machine, such as the luffing member 104, winch drums DR1 and DR2, and bucket device 10. The various settings may include, for example, the winding state of the winch ropes of winch drums DR1 and DR2 at the start of work (for example, a value indicating how much of the winch rope is wound on the winch drum).

[0116] The at least one mode switch may include, for example, an on / off mode switch 90 and an assist mode switch 91.

[0117] The load value detector 94 detects a load value that correlates with the bucket weight, which is the weight of the bucket device 10. The load value detector 94 may be, for example, a load cell. The load value detector 94 may be attached to the lower spreader 110, for example, as shown in Figure 1, to detect the load value acting on the luffing rope R3. However, the mounting position of the load value detector 94 is not limited to the lower spreader 110. For example, the load value detector 94 may be attached to the upper spreader 109 to detect the load value acting on the luffing rope R3. Alternatively, the load value detector 94 may detect the load value acting on the guy line 108.

[0118] The setting memory 95 stores the weight of the bucket device 10 calculated by the bucket weight calculation unit 73, which will be described later. Specifically, the setting memory 95 may store the bucket weight as the previous setting value when the power to the controller 70 is turned off. Then, in the next operation, the controller 70 may use the previous setting value stored in the setting memory 95 as the bucket weight.

[0119] In the second embodiment, the controller 70 sets the control mode of the crane 100 to one of a plurality of modes based on a preset determination condition. In this embodiment, the plurality of control modes may include an assist mode and a non-assist mode. The assist mode includes a bucket opening / closing mode, a power synchronization mode, and a free synchronization mode.

[0120] The assist mode is a control mode in which the controller 70 performs assist control to enable the operator to make the bucket device 10 perform predetermined operations with simple operations. The non-assist mode is a control mode in which the above-mentioned assist control is not performed (no-control mode).

[0121] In this embodiment, the controller 70 sets the control mode to assist mode when the assist mode switch 91 is ON, and sets the control mode to non-assist mode when the assist mode switch 91 is OFF. In assist mode, the controller 70 sets the control mode to bucket opening / closing mode when the opening / closing mode switch 90 is ON, and sets the control mode to synchronized control mode when the opening / closing mode switch 90 is OFF. The synchronized mode includes power synchronized mode and free synchronized mode. Specifically, these are as follows.

[0122] The assist mode switch 91 is a switch for setting the control mode of the crane 100 to assist mode. When the assist mode switch 91 is turned on by the operator, it inputs an on command signal corresponding to the on operation to the controller 70, and the controller 70 sets the control mode to assist mode. If the assist mode switch 91 is not turned on, the controller 70 does not set the control mode to assist mode, but sets the control mode to another predetermined control mode (for example, non-assist mode).

[0123] The opening / closing mode switch 90 is a switch for setting the control mode of the controller 70 to the bucket opening / closing mode. When the control mode is set to assist mode and the operator performs an ON operation for the bucket opening / closing mode, the opening / closing mode switch 90 inputs an ON command signal corresponding to the ON operation to the controller 70, and the controller 70 sets the control mode to the bucket opening / closing mode. When the control mode is set to assist mode and the ON operation is not performed to the opening / closing mode switch 90, the controller 70 sets the control mode to synchronized control mode.

[0124] As described above, in this embodiment, the tuning mode includes a power tuning mode and a free tuning mode. The controller 70 sets the control mode to either the power tuning mode or the free tuning mode by performing calculation processing as shown in the flowchart in Figure 10, for example.

[0125] The bucket opening / closing mode is a control mode that allows the bucket device 10 to perform operations including changing the open / closed state of a pair of buckets 13, 13 based on a specific operation that has been set in advance. When the control mode is set to bucket opening / closing mode, the controller 70 performs non-synchronized control such as bucket stationary closing control, bucket stationary opening control, and excavation control, which will be described later.

[0126] When the control mode is set to power synchronization mode, the controller 70 performs the same elevation synchronization control as in the first embodiment or the main auxiliary synchronization control described later. When the control mode is set to free synchronization mode, the controller 70 performs the free synchronization control described later.

[0127] The controller 70 includes a computer that includes a processing unit and memory. In the second embodiment shown in Figure 9, the controller 70 includes a lifting value calculation unit 71, an operation state determination unit 72, a bucket weight calculation unit 73, a wire tension determination unit 74, an assist mode determination unit 75, a target pilot pressure calculation unit 76, and a valve command current value calculation unit 77, and each of these functions is realized by the processing unit executing a control program stored in the memory.

[0128] The lifting height calculation unit 71 calculates the lifting height of the first winch rope R1 and the lifting height of the second winch rope R2, respectively, based on the setting data input from the operator setting device 21 to the controller 70, the detection results input from the drum rotation detectors 81 and 82 to the controller 70, and the luffing angle θ of the luffing member 104 input from the luffing member angle detector 22 to the controller 70.

[0129] The setting data input from the operator setting device 21 to the controller 70 may include, for example, specification data including the length of the luffing member 104, and may further include data relating to the relative position of the first winch drum DR1 with respect to the specific part of the luffing member 104, and data relating to the relative position of the second winch drum DR2 with respect to the specific part of the luffing member 104.

[0130] The lifting height values ​​of the winch ropes (the lifting height values ​​of the first winch rope R1 and the second winch rope R2, respectively) are values ​​that take into account the effect of changes in the elevation angle θ. When the position of a predetermined part of the winch rope in the reference state is taken as the reference (zero position), the amount of change in the position of the predetermined part of the winch rope relative to this reference is called the lifting height value of the winch rope. The predetermined part of the winch rope may be, for example, the tip of the winch rope, or it may be any other part of the winch rope. The reference state is, for example, when the winch rope is extended a predetermined length from the winch drum, and the elevation angle θ of the elevation member 104 is a predetermined angle θs.

[0131] More specifically, the reference state may be, for example, the state in which the winch rope is fully extended from the winch drum and the luffing angle θ of the luffing member 104 is 45 degrees. In this case, the lifting value of the first winch rope R1 is as follows. That is, the position of the tip of the first winch rope R1 in the state in which the first winch rope R1 is fully extended from the first winch drum DR1 and the luffing angle θ of the luffing member 104 is 45 degrees is used as the reference, and the lifting value of the first winch rope R1 is the amount of change in the position of the tip of the first winch rope R1 relative to this reference. Similarly, the lifting value of the second winch rope R2 is as follows. In other words, the lifting height of the second winch rope R2 is the amount of change in the position of the tip of the second winch rope R2 relative to the reference position when the second winch rope R2 is fully extended from the second winch drum DR2 and the luffing angle θ of the luffing member 104 is 45 degrees.

[0132] The lifting height 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 angle θ of the luffing member 104. Similarly, the lifting height 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 angle θ of the luffing member 104.

[0133] 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 drum rotation detectors 81 and 82, and the luffing angle θ of the luffing member 104 input to the controller 70 from the luffing member angle detector 22, to calculate the lifting height values ​​of the first winch rope R1 and the second winch rope R2, respectively.

[0134] The controller 70 may calculate the lifting height value Lh1 of the first winch rope R1 based on the change in the first distance Ltop-m ΔL1 relative to the reference state, the change in the height position of the upper end P1 of the luffing member 104 ΔH1 relative to the reference state, and the change in the amount of the first winch rope R1 extended ΔR1 relative to the reference state. The controller 70 may, for example, calculate the lifting height value Lh1 of the first winch rope R1 using the following equation (4).

[0135] The lifting height of the first winch rope R1 is Lh1 = -(ΔL1 + ΔH1 + ΔR1) (4)

[0136] Similarly, the controller 70 may calculate the lifting height value Lh2 of the second winch rope R2 based on the change in the second distance Ltop-a ΔL2 relative to the reference state, the change in the height position of the upper end P2 of the luffing member 104 ΔH2 relative to the reference state, and the change in the amount of the second winch rope R2 extended ΔR2 relative to the reference state. The controller 70 may, for example, calculate the lifting height value Lh2 of the second winch rope R2 using the following equation (5).

[0137] The lifting height of the second winch rope R2 is Lh2 = -(ΔL2 + ΔH2 + ΔR2) (5)

[0138] Here, we assume that the upper end P1 and the upper end P2 of the luffing member 104 are at the same height, and that the amount of the first winch rope R1 and the amount of the second winch rope R2 are both zero during the process in which the luffing angle θ of the luffing member 104 changes from θ1 to θ2. In this case, the deviation er' between the lifting height Lh1 of the first winch rope R1 and the lifting height Lh2 of the second winch rope R2 when the luffing angle θ changes from θ1 to θ2 can be expressed, for example, by the following equation (6). That is, when the luffing angle θ of the luffing member 104 changes from θ1 to θ2 with the first winch drum DR1 and the second winch drum DR2 stopped, the deviation er' between the lifting height Lh1 of the first winch rope R1 and the lifting height Lh2 of the second winch rope R2 can be expressed, for example, by the following equation (6).

[0139] er'=ΔL2−ΔL1 (6)

[0140] Therefore, in this second embodiment, the controller 70 may calculate the deviation er' and perform the elevation synchronization control based on it.

[0141] Furthermore, when the first winch drum DR1 and the second winch drum DR2 are stopped and the elevation angle θ of the elevation member 104 changes from θ1 to θ2, the absolute value of the deviation er'|er'| between the change in the lifting height Lh1 of the first winch rope R1 and the change in the lifting height Lh2 of the second winch rope R2 will be the same value as the absolute value of the distance change deviation er|er| described above.

[0142] Therefore, in this second embodiment, the controller 70 may calculate the distance change deviation er in the same manner as in the first embodiment, and perform the same elevation synchronization control as in the first embodiment based on the distance change deviation er.

[0143] The operation state determination unit 72 determines the lever operation state for the first winch operation lever 51A and the second winch operation lever 53A, respectively, based on the detection results input to the controller 70 from the first lever input detector 51B and the second lever input detector 53B. Specifically, the operation state determination unit 72 determines, based on the detection results, whether the lever operation state is a hoisting operation state, a lowering operation state, or a neutral state.

[0144] The operation state determination unit 72 may determine that the lever operation state is a winding operation state if the amount of winding operation applied to each of the first winch operation lever 51A and the second winch operation lever 53A is equal to or greater than a predetermined threshold. The operation state determination unit 72 may also determine that the lever operation state is a lowering operation state if the amount of lowering operation applied to each of the first winch operation lever 51A and the second winch operation lever 53A is equal to or greater than a predetermined threshold.

[0145] The operation state determination unit 72 may determine the pedal operation state for the first brake operation pedal 52A and the second brake operation pedal 54A, respectively, based on the detection results input to the controller 70 from the first pedal input detector 52B and the second pedal input detector 54B. Specifically, the operation state determination unit 72 may determine, based on the detection results, whether the pedal operation state is a brake state or a free state.

[0146] The bucket weight calculation unit 73 calculates the weight of the bucket device 10. Specifically, the bucket weight calculation unit 73 may calculate the weight of the bucket device 10 based on the load value detected by the load value detector 94 at the time an operator performs an input operation on the bucket weight setting device (not shown). The bucket weight setting device may include, for example, a touch panel on a monitor.

[0147] The wire tension determination unit 74 determines whether the bucket device 10 is touching the ground or not based on the load value detected by the load value detector 94 and the bucket weight. For example, the wire tension determination unit 74 may determine that the bucket device 10 is touching the ground if the load value detected by the load value detector 94 at that time is less than or equal to a predetermined first threshold that is less than the bucket weight (for example, less than or equal to 30% of the bucket weight). For example, the wire tension determination unit 74 may determine that the bucket device 10 is not touching the ground if the load value detected by the load value detector 94 at that time is greater than or equal to a predetermined second threshold that is greater than the first threshold (for example, more than or equal to 70% of the bucket weight).

[0148] The assist mode determination unit 75 determines the control mode of the crane 100. Specifically, the assist mode determination unit 75 may determine whether the control mode is bucket opening / closing mode, power synchronization mode, free synchronization mode, or non-assist mode (no control mode) by performing calculation processing as shown in the flowchart of Figure 10, which will be described later.

[0149] The target pilot pressure calculation unit 76 recognizes the current control mode (bucket opening / closing mode, power synchronization mode, free synchronization mode, or non-assist mode) based on the determination result made by the assist mode determination unit 75, and calculates the target pilot pressure to be input to the first control valve 32 and the second control valve 33, respectively, according to the control mode. For example, when the luffing operation lever 55A receives a luffing operation, the control mode is set to power synchronization mode, and the target pilot pressure calculation unit 76 calculates the target pilot pressure to be input to the first control valve 32 and the second control valve 33, respectively, based on the luffing angle θ of the luffing member 104.

[0150] The valve command current value calculation unit 77 calculates command current values ​​to be input to the first dispensing proportional valve 61A, the first retracting proportional valve 61B, the second dispensing proportional valve 63A, and the second retracting proportional valve 63B, respectively, based on the target pilot pressure calculated by the target pilot pressure calculation unit 76. Specifically, for example, the valve command current value calculation unit 77 may calculate the command current values ​​using the target pilot pressure calculated by the target pilot pressure calculation unit 76 and a map representing the relationship between the target pilot pressure and the command current values, as shown in Figure 12, for example. The controller 70 inputs the calculated command current values ​​to the proportional valves 61A, 61B, 63A, and 63B, respectively. The controller 70 may also calculate command current values ​​to be input to various switching valves included in the hydraulic circuit of the crane 100 and input the calculated command current values ​​to the switching valves.

[0151] Figure 10 is a flowchart showing an example of the calculation process performed by the controller 70 according to the second embodiment.

[0152] In step S101, the controller 70 determines whether predetermined bucket opening / closing mode conditions are met. The bucket opening / closing mode conditions are conditions for determining whether or not to set the control mode to bucket opening / closing mode. Specifically, for example, the bucket opening / closing mode conditions may be that the opening / closing mode switch 90 is in the ON state and the luffing operation lever 55A is not operated.

[0153] If the bucket opening / closing mode conditions are met (YES in step S101), specifically, if the opening / closing mode switch 90 is ON and the luffing operation lever is not operated, the controller 70 sets the control mode to the bucket opening / closing mode (step S102). If the bucket opening / closing mode conditions are not met (NO in step S101), the controller 70 performs the process in step S103.

[0154] In step S103, the controller 70 determines whether a predetermined power synchronization mode condition is met. The power synchronization mode condition is a condition for determining whether or not to set the control mode to power synchronization mode. The power synchronization mode condition may be, for example, the condition that the first winch operating lever 51A or the luffing operating lever 55A is being operated.

[0155] If the power synchronization mode condition is met (YES in step S103), specifically, if the first winch operating lever 51A or the luffing operating lever 55A is operated, the controller 70 sets the control mode to power synchronization mode (step S104). If the power synchronization mode condition is not met (NO in step S103), the controller 70 performs the process in step S105.

[0156] In step S105, the controller 70 determines whether a predetermined free-synchronization mode condition is met. The free-synchronization mode condition is a condition for determining whether or not to set the control mode to free-synchronization mode. The free-synchronization mode condition may be, for example, a neutral free mode and a main hoist free operation. Specifically, the crane 100 has a neutral free mode and a neutral brake mode as control modes. In neutral brake mode, even when the brake pedal is released and not pressed, the winch drum remains connected to the power side. That is, the winch drum will not move without lever operation. In neutral brake mode, pressing the brake pedal and then pressing the free switch activates neutral free mode. Releasing the brake pedal disconnects the winch drum from the power side, and the drum rotates due to gravity. "Main hoist free operation" refers to a state where the brake pedal is released and there is brake pressure such that the drum is disconnected from the power side, meaning the winch drum is driven by the brake pedal. This is detected by a pressure sensor that detects pedal pressure.

[0157] If the free tuning mode condition is met (YES in step S105), specifically, in neutral free mode and when there is a main winding free operation, the controller 70 sets the control mode to free tuning mode (step S106). If the free tuning mode condition is not met (NO in step S105), the controller 70 sets the control mode to non-assist mode (no control mode) (step S107).

[0158] [Power Synchronization Mode] First, let's explain the power synchronization mode.

[0159] In the second embodiment, when the power synchronization mode condition is met (YES in step S103 of Figure 10), the controller 70 transitions to the power synchronization mode and performs luffing synchronization control similar to the first embodiment or the main auxiliary synchronization control described later. Specifically, when the first winch operating lever 51A is operated, the controller 70 sets the control mode to the power synchronization mode and performs the main auxiliary synchronization control described later. When the luffing operation lever 55A is operated, the controller 70 sets the control mode to the power synchronization mode and performs the luffing synchronization control.

[0160] [Loop Synchronization Control] The loop synchronization control is the same as in the first embodiment. That is, in this loop synchronization control, the controller 70 adjusts one or both of the payout amounts of the first winch rope R1 and the second winch rope R2 in accordance with the angle change of the looping member 104 to maintain the open and closed state of the buckets 13, 13. Specifically, it is as follows.

[0161] In step S103 of the flowchart in Figure 10, if the luffing operation lever 55A is operated, the controller 70 sets the control mode to power synchronization mode and performs the luffing synchronization control. The controller 70 performs calculation processing for the luffing synchronization control as shown in the flowchart in Figure 11, for example.

[0162] In step S21, the controller 70 determines whether the luffing lever 55A is being operated. If the luffing lever 55A is being operated (YES in step S21), the controller 70 calculates the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a (step S22). If the luffing lever 55A is not being operated (NO in step S21), more specifically, if neither the luffing lever 55A nor the first winch operating lever 51A is being operated, the controller 70 performs the process shown in step S105 of the flowchart in Figure 10.

[0163] In step S23, the controller 70 calculates a correction amount (for example, the distance change deviation er described in the first embodiment) for maintaining the open / closed state of the buckets 13, 13 based on the first distance change amount ΔLtop-m and the second distance change amount ΔLtop-a.

[0164] In step S24, the controller 70 maintains the open / closed state of the buckets 13, 13 by adjusting one or both of the payout amounts of the first winch rope R1 and the second winch rope R2 based on the calculated correction amount. The controller 70 then repeats the process from step S21 onward.

[0165] [Main and Auxiliary Synchronization Control] Next, the main and auxiliary synchronization control will be explained. In step S103 of the flowchart in Figure 10, if the first winch operating lever 51A is operated, the controller 70 sets the control mode to power synchronization mode and performs the following main and auxiliary synchronization control. Main and 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.

[0166] The main auxiliary synchronization control includes opening down control, closing down control, opening up control, and closing up control. 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 a first lever operation applied to the first winch operating lever 51A.

[0167] Specifically, when an extension operation is applied to the first winch operating lever 51A, the controller 70 sets the control mode to power synchronization mode and performs the following opening-down control or closing-down control. In 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 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.

[0168] Furthermore, when a winding operation is applied to the first winch operating lever 51A, the controller 70 sets the control mode to power synchronization mode and performs the following opening-up control or closing-up control. In 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 closing-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 closed state of the bucket device 10.

[0169] [Bucket Opening / Closing Mode] Next, we will explain the bucket opening / closing mode.

[0170] When the control mode is set to bucket opening / closing mode, the controller 70 performs non-synchronized control such as bucket stationary closing control, bucket stationary opening control, and excavation control.

[0171] Bucket stationary closing control is a control method used in the bucket opening / closing mode to close the buckets 13, 13 while the bucket device 10 is stationary in the air. In bucket stationary closing control, the second winch operating lever 53A is in the neutral position, and the second brake operating pedal 54A is pressed down, meaning that the second winch drum DR2 is braked to prevent its rotation, and a winding operation is applied to the first winch operating lever 51A. This allows the first winch rope to be wound up without paying out or winding up the second winch rope, and the bucket device 10 can be operated in the closing direction while maintaining the height of the bucket device 10 in the air.

[0172] Bucket stationary opening control is a control method used in the bucket opening / closing mode to open and operate the buckets 13, 13 while the bucket device 10 is stationary in the air. In bucket stationary opening control, the second winch operating lever 53A is in the neutral position, and the second brake operating pedal 54A is pressed down, meaning that the second winch drum DR2 is braked to prevent its rotation. The first brake operating pedal 52A is then operated to reduce (weaken) the first brake force. This allows the first winch rope R1 to be unfurled and the tension of the first winch rope R1 to be released without unfurling or rewinding the second winch rope, enabling the bucket device 10 to be operated in the opening direction while maintaining its height in the air. This aerial opening operation is used, for example, in soil removal operations, such as unloading soil or other materials held in the closed bucket device 10 onto a destination (e.g., the bed of a truck).

[0173] Excavation control is the control that causes the bucket device 10 to perform an excavation operation in the bucket opening and closing mode. In excavation control, the second winch drum DR2 is left free, and the first winch rope R1 is wound up with the first winch drum DR1, thereby loosening the tension of the second winch rope R2 and causing the bucket device 10 to perform the operation of closing the bucket device 10. As a result, during the process of closing the bucket device 10 in the excavation operation, the bucket device 10 sinks down as the material to be excavated, such as soil, is excavated, and more material to be excavated can be stored inside the bucket device 10.

[0174] [Free Tuning Mode] Next, we will explain the free tuning mode.

[0175] When the control mode is set to free synchronization mode, the controller 70 performs free synchronization control to adjust the first braking force and the second braking force of the first clutch brake 40 and the second clutch brake 40 based on the amount of operation of the first pedal applied to the first brake operation pedal 52A (pedal operation amount).

[0176] The controller 70 adjusts the first brake force and the second brake force. When the control mode is set to free synchronization mode, a first brake operation that reduces the first brake force is applied to the first brake operation pedal 52A, and the bucket device 10 is in the open state, the controller 70 performs the following opening down control. In this opening down control, the controller 70 adjusts the first brake force and the second brake force so that the bucket device 10 descends by its own weight while maintaining the open state of the bucket device 10. This opening down control performed in response to an operation applied to the brake operation pedal is an example of free synchronization control.

[0177] Furthermore, when the control mode is set to free synchronization mode, a first brake operation that reduces the first brake force is applied to the first brake operation pedal 52A, and the bucket device 10 is in the closed state, the controller 70 performs the following closing down control. In this closing down control, the controller 70 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. This closing down control, which is performed in response to an operation applied to the brake operation pedal, is an example of free synchronization control. A first brake operation that reduces the first brake force is, for example, an operation that reduces the amount of pedal operation (depression amount) applied to the first brake operation pedal 52A.

[0178] The controller 70 may determine the open or closed state of the bucket device 10. That is, the controller 70 may determine whether the bucket device 10 is in an open state or a closed state. The controller 70 may determine the open or closed state of the bucket device 10 based on a first rotation amount ωm and a second rotation amount ωa.

[0179] The first technology of this disclosure is not limited to the first and second embodiments described above. The first technology of this disclosure includes, for example, the following modifications:

[0180] [Modifications] (A) Regarding the specifications of the crane, the crane according to the embodiment shown in Figure 1 does not have a jib and struts, but the specifications of the crane are not limited to those shown in Figure 1. The crane according to the disclosure may be a luffing crane equipped with a jib, front struts and rear struts, or it may be a fixed jib crane equipped with a jib and one strut. Furthermore, the crane according to the disclosure may be a crane equipped with a mast instead of a gantry (for example, a large crane).

[0181] 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.

[0182] (B) With respect to the winch rope and winch drum, in the above embodiment, the first winch rope R1 is the opening / closing rope, the second winch rope R2 is the support rope, the first winch drum DR1 is the opening / closing drum, and the second winch drum DR2 is the support drum, but these may be reversed. That is, the first winch rope R1 may be the support rope, the second winch rope R2 may be the opening / closing rope, the first winch drum DR1 may be the support drum, and the second winch drum may be the opening / closing drum.

[0183] (C) Regarding the bucket control device, in the above embodiment, the bucket control device 200 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.

[0184] (D) Operating devices The operating devices according to this disclosure may be appropriately selected depending on the type of first and second winches and their drive devices. For example, the lever input detectors 51B and 53B of the first winch operating device 51 and the second winch operating device 53 shown in Figures 2 and 3, and the pedal input detectors 52B and 54B of the first brake operating device 52 and the second brake operating device 54 may each be replaced with a device that includes a remote control valve that outputs pilot pressure corresponding to the operation and a pressure sensor that detects said pilot pressure. In this case, proportional valves 61A and 61B may be interposed between the remote control valve of the first winch operating device 51 and a pair of pilot ports of the first control valve, respectively, and proportional valves 63A and 63B may be interposed between the remote control valve of the second winch operating device 53 and a pair of pilot ports of the second control valve 33, respectively. Furthermore, the proportional valve 62 may be interposed between the remote control valve of the first brake operating device 52 and the first clutch brake 40, and the proportional valve 64 may be interposed between the remote control valve of the second brake operating device 54 and the second clutch brake 40.

[0185] (E) With respect to the winch, the first and second winches according to this disclosure may be, for example, electric winches. In this case, the hydraulic circuit shown in Figure 3 can be replaced with an electrical circuit (for example, a circuit including an inverter) that drives the electric winch.

[0186] As described above, the first technology, including the first and second embodiments of the present disclosure, provides a technology that can prevent the bucket from changing from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member. The first technology of the present disclosure includes the following first to fifth embodiments.

[0187] A bucket control device according to a first embodiment of the first technology is a control device for a construction machine, comprising: a machine body; a luffing member that can be raised and lowered relative to the machine body; a first winch drum that pays out and retracts a first winch rope hanging from the luffing member; a second winch drum positioned differently from the first winch drum and that pays out and retracts a second winch rope hanging from the luffing member; and a bucket device to which the first winch rope and the second winch rope are connected, and which has a bucket that can be opened and closed in accordance with the operation of the first winch drum and the operation of the second winch drum. The bucket control device includes a controller that performs luffing synchronization control to maintain the open and closed state of the bucket by adjusting one or both of the payout amounts of the first winch rope and the second winch rope in accordance with the angle change of the luffing member during the luffing operation of the luffing member.

[0188] If the luffing synchronization control is not performed, even if the first and second winch drums for opening and closing the bucket are stopped, the bucket may change from a closed state to an open state or from an open state to a closed state during the luffing operation of the luffing member due to a difference in the relative position of the first winch drum with respect to the luffing member and the relative position of the second winch drum with respect to the luffing member. In other words, if the luffing synchronization control is not performed, the open or closed state of the bucket may change against the operator's will during the luffing operation of the luffing member.

[0189] On the other hand, in the bucket control device according to the first embodiment of the first technology, the controller performs luffing synchronization control to maintain the open and closed state of the bucket by adjusting one or both of the payout amounts of the first winch rope and the second winch rope in accordance with the angle change of the luffing member during the luffing operation of the luffing member. This suppresses the bucket from changing from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member.

[0190] A bucket control device according to a second embodiment of the first technology preferably further comprises the following configuration in addition to the bucket control device according to the first embodiment. That is, in the bucket control device according to the second embodiment, the controller preferably calculates a first distance change amount that changes in accordance with the angle change, which is the change in a first distance from the first winch drum to a predetermined first part of the luffing member, and calculates a second distance change amount that changes in accordance with the angle change, which is the change in a second distance from the second winch drum to a predetermined second part of the luffing member, and adjusts one or both of the payout amount of the first winch rope and the payout amount of the second winch rope based on the first distance change amount and the second distance change amount.

[0191] If the luffing synchronization control described above is not performed, the relative position of the first winch drum with respect to the luffing member and the relative position of the second winch drum with respect to the luffing member will be different, which may cause a difference between the first distance change and the second distance change during the luffing operation of the luffing member, and as a result, the opening and closing state of the bucket may change.

[0192] On the other hand, in the bucket control device according to the second embodiment of the first technology, the controller adjusts either or both of the amount of the first winch rope unwinded and the amount of the second winch rope unwinded based on the first distance change and the second distance change, thereby maintaining the open or closed state of the bucket.

[0193] In the second embodiment of the first technology, if the first winch rope extends from the first winch drum to the upper end of the luffing member and hangs down from the upper end to the bucket device, the predetermined first portion may be the upper end of the luffing member. Similarly, if the second winch rope extends from the second winch drum to the upper end of the luffing member and hangs down from the upper end to the bucket device, the predetermined second portion may be the upper end of the luffing member.

[0194] A bucket control device according to a third embodiment of the first technology preferably further comprises the following configuration in addition to the bucket control device according to the first or second embodiment. That is, in the third embodiment, the construction machine further comprises a luffing device which is an operating device that receives a luffing operation for luffing the luffing member, and the controller preferably performs luffing synchronization control when the luffing device receives the luffing operation. In this third embodiment, the controller can perform the luffing synchronization control at an appropriate timing based on the luffing operation.

[0195] A construction machine according to the fourth aspect of the first technology comprises the machine body, the luffing member, the first winch drum, the second winch drum, the bucket device, and a bucket control device according to any one of the first to third aspects. In this fourth aspect, the controller can prevent the bucket from changing from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member.

[0196] A bucket control method (bucket open / closed state maintenance method) according to a fifth aspect of the first technology is a method using a bucket control device according to any one of the first to third aspects. The bucket control method (bucket open / closed state maintenance method) includes the controller adjusting one or both of the payout amount of the first winch rope and the payout amount of the second winch rope in accordance with the angle change of the luffing member during the luffing operation of the luffing member to maintain the open / closed state of the bucket. This bucket control method (bucket open / closed state maintenance method) according to the fifth aspect can prevent the bucket from changing from a closed state to an open state or from an open state to a closed state against the operator's will during the luffing operation of the luffing member.

[0197] [Second Technology] Next, the second technology of this disclosure will be described. The second technology can be implemented in combination with the first technology described above. The second technology can also be implemented on its own without being combined with the first technology.

[0198] First, let me explain the problems that the second technology will solve.

[0199] [Second Technical Problem to be Solved] Conventionally, construction machines equipped with a bucket device having an openable and closable bucket are known (for example, Patent Documents 1 and 2). In this construction machine, the bucket device lands with the bucket open, and then excavates the ground and holds soil by closing the bucket. After that, the bucket device rises with the bucket closed and leaves the ground, and then the upper rotating body of the construction machine rotates to move to directly above the soil removal site. Then, the bucket device opens the bucket directly above the soil removal site and discharges soil from the bucket.

[0200] In conventional construction machinery, after the bucket device excavates the ground and holds the soil, a large impact may be applied to the construction machinery when the bucket device rises and leaves the ground.

[0201] The second technology of this disclosure aims to provide a technology that can mitigate the impact on a construction machine when a bucket device rises and leaves the ground.

[0202] A bucket control device according to the first aspect of the second technology 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 to which the first winch rope and the second winch rope are connected and which can be raised and lowered in accordance with the operation of the first winch drum and the operation of the second winch drum; and an operating device for receiving a hoisting operation to raise the bucket device, wherein the bucket control device includes a controller that performs ground-away control, which operates the first winch drum and the second winch drum such that the increase in winding speed per unit time is smaller than the increase in winding speed per unit time corresponding to the amount of the hoisting operation, when predetermined ground-away conditions for determining when the bucket device leaves the ground are met.

[0203] Embodiments of the second technology of this disclosure will be described with reference to the drawings.

[0204] The second technology includes the following third embodiment. The third embodiment of the second technology can be implemented in combination with the first embodiment of the first technology described above, and can also be implemented in combination with the second embodiment of the first technology described above. However, the third embodiment of the second technology can also be implemented independently without being combined with either the first or second embodiment of the first technology.

[0205] [Third Embodiment] The third embodiment will now be described in detail. The general outline of the crane 100 according to the third embodiment is as described with reference to Figures 1 to 4.

[0206] The crane 100 according to the third embodiment includes a luffing member angle detector 22, a first drum rotation detector 81, a second drum rotation detector 82, and a load value detector 94.

[0207] The luffing member angle detector 22 detects the luffing angle θ of the luffing member 104 and inputs the detection result to the controller 70. In the third embodiment, the luffing member angle detector 22 detects the boom angle, which is the angle of the boom of the luffing member 104, as the luffing angle θ. The luffing angle θ is the angle of the luffing member 104 with respect to a predetermined reference. The reference may be, for example, a horizontal line or a horizontal plane, another straight line or another plane, the upper slewing body 102, or the lower body 101.

[0208] The first drum rotation detector 81 detects a first rotation amount ωm, which is the amount of rotation of the first winch drum DR1, and inputs the detection result to the controller 70. The second drum rotation detector 82 detects a second rotation amount ωa, which is the amount of rotation of the second winch drum DR2, and inputs the detection result to the controller 70.

[0209] The controller 70, described later, can calculate the amount of the first winch rope R1 to be unwound based on a first rotation amount ωm input from the first drum rotation detector 81. The controller 70 can also calculate the amount of the second winch rope R2 to be unwound based on a second rotation amount ωa input from the second drum rotation detector 82.

[0210] The load value detector 94 detects a load value that correlates with the bucket weight, which is the weight of the bucket device 10. The load value detector 94 may be, for example, a load cell. The load value detector 94 may be attached to the lower spreader 110, for example, as shown in Figure 1, to detect the load value acting on the luffing rope R3. However, the mounting position of the load value detector 94 is not limited to the lower spreader 110. For example, the load value detector 94 may be attached to the upper spreader 109 to detect the load value acting on the luffing rope R3. Alternatively, the load value detector 94 may detect the load value acting on the guy line 108.

[0211] Next, a bucket control device 200 according to the third embodiment will be described.

[0212] The bucket control device 200 is a control device for the crane 100. In the third embodiment, the bucket control device 200 is provided on the crane 100.

[0213] The bucket control device 200 includes a controller 70.

[0214] The controller 70 comprises a computer having an arithmetic processing unit and memory. The restriction control and ground displacement control performed by the controller 70, as described later, are realized by the arithmetic processing unit executing a control program stored in the memory.

[0215] The controller 70 performs ground-lift control when predetermined ground-lift conditions are met to determine when the bucket device 10 leaves the ground. This ground-lift control operates the first winch drum DR1 and the second winch drum DR2 such that the increase in winding speed per unit time is smaller than that of the winding operation corresponding to the amount of winding operation. In this third embodiment, since the ground-lift control described above is performed when the bucket device 10 rises and leaves the ground, the impact on the crane 100 is mitigated.

[0216] Specifically, in the third embodiment, the controller 70 calculates a target winding value, which is a target value that increases in proportion to the increase in the amount of the hoisting operation, and in the ground-away control, operates the first winch drum DR1 and the second winch drum DR2 based on a processed target value obtained by applying a predetermined filter process to the winding target value. The processed target value is the output of the filter process. In this case, the controller 70 can acquire the processed target value, whose rate of increase up to the winding target value is suppressed by the filter process, as a target pilot pressure, and operates the first winch drum DR1 and the second winch drum DR2 based on the acquired processed target value. Therefore, the controller 70 can operate the first winch drum DR1 and the second winch drum DR2 such that the amount of increase in winding speed per unit time is smaller compared to the winding operation corresponding to the amount of the hoisting operation. As a result, the impact applied to the crane 100 when the bucket device 10 leaves the ground is effectively mitigated. Furthermore, the winding operation corresponding to the amount of winding operation is the operation of the first winch drum DR1 and the second winch drum DR2 when the controller 70 operates the first winch drum DR1 and the second winch drum DR2 based on the winding target value.

[0217] In the third embodiment, the controller 70 performs the limit control when the first winch operating device 51 receives the hoisting operation while the bucket device 10 is in contact with the ground. The limit control is a control that limits the winding speed of the first winch rope R1 and the second winch rope R2 to a speed smaller than the maximum winding speed corresponding to the maximum amount of the hoisting operation. As a result, the winding speed just before the ground-away control is started, that is, just before the bucket device 10 leaves the ground, is kept smaller than the maximum winding speed. As a result, the controller 70 can start the ground-away control, which is executed after the limit control, from a speed smaller than the maximum winding speed, so that the bucket device 10 leaves the ground slowly during the limit control and the ground-away control.

[0218] Specifically, in the third embodiment, the controller 70 calculates a target winding value, which is a target value that increases in proportion to the increase in the amount of winding operation, limits the target pilot pressure to a limit target value smaller than the winding target value in the limit control, operates the first winch drum DR1 and the second winch drum DR2 based on the limit target value, and in the ground release control, obtains a processed target value as the target pilot pressure by applying a predetermined filter process to the winding target value so that it gradually increases from the limit target value to the winding target value, and operates the first winch drum DR1 and the second winch drum DR2 based on the obtained target pilot pressure.

[0219] Figures 13A, 13B, and 13C are graphs illustrating the limit control and the ground release control. Figure 13A is a graph showing an example of the temporal change in the amount of winding operation applied to the first winch operating lever 51A of the first winch operating device 51. Figure 13B is a graph showing an example of the temporal change in the target pilot pressure. Figure 13C is a graph showing an example of the temporal change in wire tension.

[0220] The bucket device 10 lands with its buckets 13, 13 open, and then performs an excavation operation by closing the buckets 13, 13 to excavate the ground and hold the soil. After that, the bucket device 10 performs an upward movement by rising with the buckets 13, 13 closed, and leaves the ground. Then, the bucket device 10 performs a movement operation by rotating its upper rotating body 102 to move to directly above the soil discharge site (not shown in the figure). Then, the bucket device 10 performs a soil discharge operation by opening the buckets 13, 13 and discharging the soil from the buckets 13, 13.

[0221] Of the series of operations described above, in order to have the bucket device 10 perform the lifting operation after the completion of the excavation operation, the operator applies a hoisting operation to one or both of 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. If the control mode of the crane 100 is set to the assist mode (specifically the power synchronization control mode) described later, in order to have the bucket device 10 perform the lifting operation after the completion of the excavation operation, the operator applies a hoisting operation to only the first winch operating lever 51A of the two winch operating levers 53A. As a result, the first winch drum DR1 and the second winch drum DR2 operate in sync, and the first winch drum DR1 and the second winch drum DR2 wind up the first winch rope R1 and the second winch rope R2, respectively. In the specific example shown in Figure 13A, the amount of winding operation that the first winch operating lever 51A receives at time t1 is the maximum amount of operation (full lever operation).

[0222] [When limit control and ground release control are not performed] If the controller 70 does not perform the limit control and ground release control, the winding target value, which is the target pilot pressure corresponding to the amount of winding operation, will show a temporal change as shown by the dashed line in Figure 13B, and the wire tension will show a temporal change as shown by the dashed line in Figure 13C. Note that the wire tension is the load value detected by the load value detector 94 or a value calculated using the said load value (a value correlated with the said load value). Specifically, the wire tension may be the load value acting on the luffing rope R3 or a value correlated with the said load value. The wire tension may be the load value acting on the guy line 108 or a value correlated with the said load value.

[0223] Figure 14 shows an example of a map representing the relationship between the amount of winding operation and the winding target value. Figure 15 shows an example of a map representing the relationship between the target pilot pressure and the commanded current value. The controller 70 stores the maps shown in Figure 14 and Figure 15.

[0224] In the third embodiment, the winding target value is the target pilot pressure. The target pilot pressure is the target value of the pilot pressure input to the winding pilot port of the first control valve 32 and the winding pilot port of the second control valve 33, respectively. Therefore, the target pilot pressure is a value that increases in proportion to the increase in the amount of winding operation and is a value that correlates with the winding speed of the first winch rope R1 and the second winch rope R2.

[0225] The command current value is a command value (current value) that the controller 70 inputs to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively, in order to output the target pilot pressure as a secondary pressure to each of the first winding proportional valve 61B and the second winding proportional valve 63B.

[0226] First, when the bucket device 10 is in contact with the ground and the first winch operating lever 51A of the first winch operating device 51 receives the hoisting operation at time t1, the controller 70 uses the amount of the hoisting operation included in the detection result of the first lever input detector 51B and the map shown in Figure 14 to calculate a target winding value as the target pilot pressure corresponding to the amount of the hoisting operation (for example, the maximum amount of the operation). In this case, as shown by the dashed line in Figure 13B, the target pilot pressure increases rapidly from zero to the maximum target value at or near time t1.

[0227] Next, the controller 70 uses the calculated target pilot pressure and the map shown in Figure 15 to calculate the command current values ​​to be input to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. The controller 70 then inputs the calculated command current values ​​to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. As a result, a pilot pressure corresponding to the maximum operating amount is applied to the winding pilot port of the first control valve 32 and the winding pilot port of the second control valve 33, respectively, and the opening degrees of the first control valve 32 and the second control valve 33 are adjusted to a size corresponding to the maximum operating amount. Consequently, the first winch motor 34 and the second winch motor 35 are each supplied with hydraulic fluid at a flow rate corresponding to the maximum operating amount of the winding operation.

[0228] In this case, the first winch motor 34 and the second winch motor 35 each rotate at a speed (maximum speed) corresponding to the maximum amount of the hoisting operation, so the first winch rope R1 and the second winch rope R2 are wound up at a winding speed (maximum winding speed) corresponding to the maximum amount of the hoisting operation. Then, when the bucket device 10 leaves the ground at time t2, the weight of the bucket device 10 acts on the first winch rope R1 and the second winch rope R2, so the wire tension rises rapidly as shown by the dashed line in Figure 13C. As a result, a large impact is applied to the luffing member 104 of the crane 100.

[0229] [When limit control and ground-away control are performed] When the controller 70 performs the limit control and ground-away control, the target pilot pressure shows a temporal change as shown by the solid line in Figure 13B, and the wire tension shows a temporal change as shown by the solid line in Figure 13C. Specifically, it is as follows.

[0230] [Limitation Control] First, the limitation control will be explained. The controller 70 performs the limiting control when the bucket device 10 is in contact with the ground and the first winch operating lever 51A of the first winch operating device 51 receives the hoisting operation at time t1. The limiting control is a control to limit the winding speed of the first winch rope R1 and the second winch rope R2 to a speed smaller than the maximum winding speed corresponding to the maximum amount of the hoisting operation.

[0231] Specifically, in the limit control, if the bucket device 10 is in contact with the ground and the first winch operating lever 51A of the first winch operating device 51 receives the hoisting operation at time t1, the controller 70 sets the target pilot pressure to a limit target value smaller than the winding target value, even if the amount of the hoisting operation is the maximum amount. In this case, as shown by the solid line in Figure 13B, the target pilot pressure is maintained at the limit target value from time t1 to time t2. In the specific example shown in Figure 13B, the limit target value is less than or equal to half of the maximum target value.

[0232] The controller 70 uses the set target pilot pressure (the limit target value) and the map shown in Figure 15 to calculate the command current value to be input to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. The controller 70 then inputs the calculated command current value to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. As a result, the winding pilot port of the first control valve 32 and the winding pilot port of the second control valve 33 are not applied with a pilot pressure corresponding to the maximum operating amount (i.e., a pilot pressure corresponding to the maximum target value), but rather with a pilot pressure corresponding to a limit target value that is smaller than the maximum target value. Therefore, the opening degrees of the first control valve 32 and the second control valve 33 are not adjusted to a size corresponding to the maximum operating amount (i.e., a size corresponding to the maximum target value), but rather to a size corresponding to a limit target value that is smaller than the maximum target value. As a result, the first winch motor 34 and the second winch motor 35 are not supplied with hydraulic fluid at a flow rate corresponding to the maximum amount of the hoisting operation (i.e., a flow rate corresponding to the maximum target value), but rather at a flow rate corresponding to a limiting target value smaller than the maximum target value (i.e., a flow rate less than the flow rate corresponding to the maximum target value). Therefore, from the time when the first winch operating lever 51A of the first winch operating device 51 receives the hoisting operation at time t1 (time t1) while the bucket device 10 is in contact with the ground (time t1), until the time when the ground-off condition is met (time t2), the rotational speed of the first winch drum DR1 and the second winch drum DR2 can be made slower than when the limiting control is not performed.

[0233] [Ground Detachment Control] Next, ground detachment control will be described. When the ground detachment condition is met, the controller 70 terminates the restriction control and starts the ground detachment control.

[0234] The ground-away condition includes at least the first winch operating lever 51A of the first winch operating device 51 being subjected to the hoisting operation. The ground-away condition may also include the first winch operating lever 51A of the first winch operating device 51 being subjected to the hoisting operation and the wire tension being greater than or equal to a predetermined value. The ground-away condition may also include the first winch operating lever 51A of the first winch operating device 51 being subjected to the hoisting operation, the wire tension being greater than or equal to a predetermined value, and the control mode described later being the power-synchronized mode. The ground-away condition may also include the first winch operating lever 51A of the first winch operating device 51 being subjected to the hoisting operation, the wire tension being greater than or equal to a first predetermined value, the wire tension being less than or equal to a second predetermined value in the immediately preceding control cycle, and the control mode being the power-synchronized mode. The second predetermined value is a value smaller than the first predetermined value. The fact that the wire tension is greater than or equal to the first predetermined value, and that the wire tension was less than or equal to the second predetermined value in the immediately preceding control cycle, can be rephrased as the wire tension increasing from a value less than or equal to the second predetermined value to a value greater than or equal to the first predetermined value.

[0235] Specifically, for example, the controller 70 may sequentially calculate the winding target value, and in the ground release control, perform filtering that includes the winding target value as input and outputs a processed target value, and operate the first winch drum DR1 and the second winch drum DR2 based on the processed target value. As described above, the winding target value is a target value that increases in proportion to the increase in the amount of the winding operation.

[0236] The filtering process is a process that outputs the processed target value for an input (filter input) that includes the winding target value. The filtering process suppresses the amount of change per unit time of the processed target value (output value) according to the characteristics of the filtering process. The filtering process may be, for example, a low-pass filter. The low-pass filter (LPF) used in the low-pass filtering process may be, for example, a digital filter. The digital filter may be, for example, an FIR filter (FIR: Finite Impulse Response) such as a moving average filter, or an IIR filter (IIR: Infinite Impulse Response). The low-pass filter may be, for example, a low-pass filter including a capacitor and a resistor, a low-pass filter including a coil and a capacitor, or another known low-pass filter.

[0237] The transfer function Kd(z) of the digital filter can be expressed, for example, by the following equation (7).

[0238]

[0239] In equation (7) above, "al" and "bk" are filter coefficients. "al" is a coefficient mainly relating to the filter output, and "bk" is a coefficient mainly relating to the filter input. These coefficients are determined so that the desired characteristics are obtained in the digital filter. "z-l" and "z-k" are delay elements, respectively.

[0240] The specific calculation method for a digital filter that can realize the above transfer function Kd(z) is not particularly limited, but the direct type of IIR filter can be expressed by, for example, the following equation (8).

[0241]

[0242] In equation (8) above, "y" is the filter output (output signal) from the filter, "u" is the filter input (input signal) input to the filter, and "ts" is the filter update period (control period). "y(t)" is the filter output at that point in time (the current point in time), "y(t-lts)" is the filter output from "lts" periods ago, and "u(t-kts)" is the filter input from "kts" periods ago. Note that when "k=0", "u(t-kts)" is "u(t)", which represents the filter input at that point in time (the current point in time).

[0243] In the third embodiment, the filter input is the target pilot pressure. However, the filter input may be a current value correlated with the target pilot pressure (e.g., a command current value), a speed correlated with the target pilot pressure (e.g., a winding speed), or another physical quantity correlated with the target pilot pressure.

[0244] Next, a specific example of the case where the digital filter is a moving average filter will be described. Here, for the sake of simplicity, we will describe the case where the moving average filter calculates the average value of the five most recent data points. In the following description, the update period (control period) of the filter processing will be denoted as "ts". In this case, when the ground separation condition is met at time t2 in Figures 13A, 13B, and 13C, the controller 70 calculates the average value of the five data points, consisting of the winding target value (maximum target value) at time t2 and the four data points prior to time t2, as the post-processing target value for the first period in the initial (first period) filter processing. Each of the four data points in the first period is the limit target value. Next, in the second cycle of filtering, the controller 70 calculates the average value of five data points, consisting of the winding target value (maximum target value) at time (t2 + ts), the winding target value (maximum target value) at time t2 (the data from one cycle prior), and three data points prior to time t2, as the target value after processing for the second cycle. Each of the three data points in the second cycle is the limit target value. Next, in the third cycle of filtering, the controller 70 calculates the average value of five data points, consisting of the winding target value (maximum target value) at time (t2 + 2ts), the winding target value (maximum target value) at time (t2 + ts) (the data from one cycle prior), the winding target value (maximum target value) at time t2 (the data from two cycles prior), and two data points prior to time t2, as the target value after processing for the third cycle. Each of the two data points in the third cycle is the limit target value. The controller 70 continues filtering for the fourth cycle and beyond in the same manner.

[0245] Furthermore, even when the digital filter is a filter other than the moving average filter (for example, the direct type of the IIR filter described above), in the initial control cycle, such as the first cycle immediately after the ground separation condition is met, the limit target value may be used as the filter input "u(t-kts)" before the time when the ground separation condition is met in the right-hand side of equation (8) above. Also, in the initial control cycle, the limit target value may be used as the filter output "y(t-lts)" before the time when the ground separation condition is met in the right-hand side of equation (8) above, or a predetermined value different from the limit target value may be used.

[0246] In Figure 13B, the dashed line that increases in a step-like manner during the time period from time t2 to time t3 shows the waveform of the target pilot pressure when the low-pass filter processing is not applied to the winding target value. In the specific example shown in Figure 13A, the amount of winding operation received by the first winch operating lever 51A at time t2 is the maximum amount of operation (full lever operation), so as shown by the dashed line in Figure 13B, the winding target value at time t2 is the maximum target value. Therefore, if the ground-away condition is met and the low-pass filter processing is not applied to the winding target value, the target pilot pressure increases rapidly from the limit target value to the maximum target value, which is the winding target value, as shown by the step-like dashed waveform during the time period from time t2 to time t3.

[0247] In Figure 13B, the solid line that gradually increases with the passage of time from time t2 to time t3 represents the output waveform (waveform of the processed target value) when the low-pass filter processing is applied to the winding target value. That is, the output waveform represents the temporal change of the processed target value, which is the output of the low-pass filter processing. The output of the low-pass filter processing exhibits a transient response corresponding to the filter characteristics of the low-pass filter (for example, the filter characteristics determined by the coefficients). In other words, the temporal change of the processed target value can be set to the desired characteristics by appropriately adjusting the filter characteristics of the low-pass filter.

[0248] When the ground-away condition is met, the controller 70 terminates the limit control and starts the ground-away control. When this ground-away control is started, the controller 70 controls the operation of the first winch drum DR1 and the second winch drum DR2 based on the processed target value, which is a target pilot pressure obtained by applying the low-pass filter processing to the winding target value. The processed target value, shown by a solid line waveform that curves smoothly during the time period from time t2 to time t3 in Figure 13B, gradually increases from the limit target value to the winding target value (maximum target value) in such a manner that the amount of increase in the value per unit time from the limit target value to the winding target value (maximum target value) is small, compared to the case where it increases sharply from the limit target value to the winding target value (maximum target value) at time t2, as shown by a stepped dashed line waveform.

[0249] The controller 70 uses the acquired post-processing target value (target pilot pressure) and the map shown in Figure 15 to calculate the command current value to be input to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. The controller 70 then inputs the calculated command current value to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. As a result, during the time period from time t2 to time t3, the winding pilot port of the first control valve 32 and the winding pilot port of the second control valve 33 are not subjected to a pilot pressure corresponding to the winding target value (maximum target value) shown by the dashed line in Figure 13B, but rather to a pilot pressure corresponding to the post-processing target value shown by the solid line in Figure 13B. Therefore, the opening degrees of the first control valve 32 and the second control valve 33 are not adjusted to a magnitude corresponding to the winding target value (maximum target value), but rather to a magnitude corresponding to the post-processing target value. As a result, the first winch motor 34 and the second winch motor 35 are supplied with hydraulic fluid at a flow rate corresponding to the post-processing target value, rather than at a flow rate corresponding to the winding target value (maximum target value). Therefore, from the time when the ground-away condition is met (time t2) until the time when the ground-away control termination condition is met (time t3), the rotational speeds of the first winch drum DR1 and the second winch drum DR2 can be made slower than when the ground-away control is not performed, and moreover, they can be smoothly increased to a size corresponding to the maximum operating amount, that is, to a size corresponding to the winding target value (maximum target value).

[0250] The ground-away control termination condition is a condition for determining whether or not to terminate the ground-away control. The ground-away control termination condition may include, for example, a condition that the difference between the processed target value, which is the value after applying the low-pass filter processing, and the winding target value, which is the value before applying the low-pass filter processing, is less than or equal to a predetermined threshold value. The ground-away control termination condition may also include, for example, a condition that the control mode of the crane 100 is not the power synchronization mode described later. The ground-away control termination condition may also include, for example, a condition that the first winch operating lever 51A of the first winch operating device 51 is not receiving the winding operation.

[0251] Figure 16 is a flowchart showing an example of the calculation process for the limit control performed by the controller 70.

[0252] In step S11 of Figure 16, the controller 70 determines whether the limit control initiation condition has been met. If the limit control initiation condition is met (YES in step S11), the controller 70 performs the limit control in step S12 of Figure 16. On the other hand, if the limit control initiation condition is not met (NO in step S11), the controller 70 performs unrestricted control in step S13 of Figure 16 without performing the limit control. Unrestricted control will be described later.

[0253] Figure 17 is a diagram illustrating the switching between the normal mode for performing the unrestricted control or the restricted control and the slow-operation mode for performing the ground-away control. As shown in Figure 17, the controller 70 may switch the control mode of the crane 100 from the normal mode to the slow-operation mode when the ground-away condition is met, and switch the control mode of the crane 100 from the slow-operation mode to the normal mode when the ground-away control termination condition is met.

[0254] The aforementioned limit control initiation conditions include the condition that the bucket device 10 is in contact with the ground and the first winch operating device 51 has received the hoisting operation. For example, the limit control initiation conditions may include the condition that the operation received by the first winch operating lever 51A is the hoisting operation, the amount of operation is greater than or equal to a predetermined threshold, and the wire tension is less than or equal to a predetermined threshold (for example, the wire tension is less than or equal to the first threshold described later). Specifically, it is as follows.

[0255] The controller 70 may determine whether the bucket device 10 is touching the ground or not based on the load value detected by the load value detector 94 and the bucket weight. For example, the controller 70 may determine that the bucket device 10 is touching the ground if the load value detected by the load value detector 94 at that time is less than or equal to a first threshold, which is a predetermined threshold that is less than the bucket weight (for example, if the load value is 30% or less of the bucket weight). For example, the controller 70 may determine that the bucket device 10 is not touching the ground if the load value detected by the load value detector 94 at that time is greater than or equal to a second threshold, which is a predetermined threshold that is greater than the first threshold (for example, if the load value is 70% or more of the bucket weight).

[0256] The controller 70 determines whether the first winch operating device 51 has received the hoisting operation based on the detection result from the lever input detector 51B of the first winch operating device 51. Specifically, if the lever operation received by the first winch operating lever 51A is the hoisting operation, and the amount of the hoisting operation is equal to or greater than the threshold amount, the controller 70 may determine that the first winch operating device 51 has received the hoisting operation.

[0257] As described above, the limiting control is a control for limiting the winding speed of the first winch rope R1 and the second winch rope R2 to a speed smaller than the maximum winding speed corresponding to the maximum amount of the winding operation. Specifically, in the limiting control, the controller 70 sets the target pilot pressure to a limiting target value smaller than the maximum target value, even if the amount of the winding operation is, for example, the maximum amount of the winding operation. That is, in the limiting control, the controller 70 limits the feedforward value (FF value) (step S12 in Figure 16).

[0258] The aforementioned unrestricted control is a control for adjusting the winding speed of the first winch rope R1 and the second winch rope R2 to a speed corresponding to the amount of winding operation. Specifically, in the unrestricted control, the controller 70 sets the target pilot pressure to a value corresponding to the amount of winding operation. The controller 70 sets the target winding value, calculated using the amount of winding operation included in the detection result of the first lever input detector 51B and the map shown in Figure 14, as the target pilot pressure. In other words, in the unrestricted control, the controller 70 does not restrict the feedforward value (FF value) (step S13 in Figure 16).

[0259] Figure 18 is a flowchart showing an example of the calculation process for the ground separation control performed by the controller 70.

[0260] In step S20 of Figure 18, the controller 70 determines whether the limit control start condition is met. If the limit control start condition is met (YES in step S20), the controller 70 performs the limit control in step S21 of Figure 18 and processes in step S22. If the limit control start condition is not met (NO in step S20), the controller 70 processes in step S22 of Figure 18.

[0261] In step S22 of Figure 18, the controller 70 determines whether the control mode is slow operation mode. If the control mode is slow operation mode (YES in step S22), the controller 70 performs the process in step S23 of Figure 18. That is, in step S23, the controller 70 applies the low-pass filter process to the winding target value calculated using the winding operation amount included in the detection result of the first lever input detector 51B and the map shown in Figure 14, and obtains the processed target value.

[0262] In step S24 of Figure 18, the controller 70 uses the acquired post-processing target value (target pilot pressure) and the map shown in Figure 15 to calculate the command current values ​​to be input to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively. Then, in step S25 of Figure 18, the controller 70 inputs the calculated command current values ​​to the first winding proportional valve 61B and the second winding proportional valve 63B, respectively.

[0263] If the control mode is not the slow-operation mode (NO in step S22 of Figure 18), that is, if the control mode is the normal mode, the controller 70 performs the processing in steps S24 and S25 of Figure 18 without performing the filtering process in step S23 of Figure 18.

[0264] The controller 70 repeatedly executes a control loop that includes the control flow of steps S20 to S25 shown in Figure 18, and other control flows not shown.

[0265] The main features of the bucket control device 200 according to the third embodiment are as described above.Modifications including other features of the bucket control device 200 will be described below, but the bucket control device in this disclosure is not limited to the following modifications.

[0266] Figure 19 is a block diagram showing the controller 70 and related main components of a bucket control device 200 according to a modified example of the third embodiment. Figure 20 is a flowchart showing an example of the calculation processing performed by the controller 70 of the bucket control device 200 according to the modified example.

[0267] The basic configuration of the modified bucket control device 200 and the basic configuration of the crane 100 equipped with the modified bucket control device 200 are the same as those of the bucket control device 200 and the crane 100 according to the third embodiment described with reference to Figures 1 to 4 and Figures 13A to 22. The modified bucket control device 200 selects one mode from a predetermined number of modes based on predetermined conditions and sets the control mode of the crane 100 to the selected mode.

[0268] As shown in Figure 19, the modified crane 100 includes an operator setting device 21, a first drum rotation detector 81, a second drum rotation detector 82, a luffing member angle detector 22, at least one mode switch, lever input detectors 51B, 53B, 55B, pedal input detectors 52B, 54B, a load value detector 94, and a setting memory 95 (previous setting memory).

[0269] The first drum rotation detector 81, the second drum rotation detector 82, the luffing member angle detector 22, the lever input detectors 51B, 53B, the pedal input detectors 52B, 54B, and the load value detector 94 are the same as those described above for the third embodiment.

[0270] The operator setting device 21 is an input device for the operator to input various settings necessary for the operation of the crane 100 according to the modified example. The operator setting device 21 receives input from the operator for making the various settings. The operator setting device 21 may be located, for example, inside the cabin 114. The operator setting device 21 may include, for example, a monitor touch panel. The various settings may include, for example, specification data for the main components constituting the construction machine, such as the luffing member 104, winch drums DR1 and DR2, and bucket device 10. The various settings may include, for example, the winding state of the winch ropes of winch drums DR1 and DR2 at the start of work (for example, a value indicating how much of the winch rope is wound on the winch drum).

[0271] The at least one mode switch may include, for example, an on / off mode switch 90 and an assist mode switch 91.

[0272] The setting memory 95 stores the weight of the bucket device 10 calculated by the bucket weight calculation unit 73, which will be described later. Specifically, the setting memory 95 may store the bucket weight as the previous setting value when the power to the controller 70 is turned off. Then, in the next operation, the controller 70 may use the previous setting value stored in the setting memory 95 as the bucket weight.

[0273] In this modified example, the controller 70 sets the control mode of the crane 100 to one of several modes based on a preset determination condition. The multiple control modes may include an assist mode and a non-assist mode. The assist mode includes a bucket opening / closing mode, a power synchronization mode, and a free synchronization mode.

[0274] The assist mode is a control mode in which the controller 70 performs assist control to enable the operator to make the bucket device 10 perform predetermined operations with simple operations. The non-assist mode is a control mode in which the above-mentioned assist control is not performed (no-control mode).

[0275] In the third embodiment, the controller 70 sets the control mode to assist mode when the assist mode switch 91 is ON, and sets the control mode to non-assist mode when the assist mode switch 91 is OFF. In assist mode, the controller 70 sets the control mode to bucket opening / closing mode when the opening / closing mode switch 90 is ON, and sets the control mode to synchronized control mode when the opening / closing mode switch 90 is OFF. The synchronized mode includes power synchronized mode and free synchronized mode. Specifically, these are as follows.

[0276] The assist mode switch 91 is a switch for setting the control mode of the crane 100 to assist mode. When the assist mode switch 91 is turned on by the operator, it inputs an on command signal corresponding to the on operation to the controller 70, and the controller 70 sets the control mode to assist mode. If the assist mode switch 91 is not turned on, the controller 70 does not set the control mode to assist mode, but sets the control mode to another predetermined control mode (for example, non-assist mode). The assist mode switch 91 may be, for example, an input device provided on a monitor such as a touch panel located inside the cabin, or it may be an input device having a push button located inside the cabin (for example, a push button provided on an operating member such as an operating lever).

[0277] The opening / closing mode switch 90 is a switch for setting the control mode of the controller 70 to the bucket opening / closing mode. When the control mode is set to assist mode and the operator performs an ON operation for the bucket opening / closing mode, the opening / closing mode switch 90 inputs an ON command signal corresponding to the ON operation to the controller 70, and the controller 70 sets the control mode to the bucket opening / closing mode. When the control mode is set to assist mode and the ON operation is not performed to the opening / closing mode switch 90, the controller 70 sets the control mode to synchronized control mode. The opening / closing mode switch 90 may be, for example, an input device having a push button located inside the cabin, or an input device provided on a monitor such as a touch panel located inside the cabin. The push button may be located on an operating member such as an operating lever.

[0278] The controller 70 sets the control mode to one of the following: bucket opening / closing mode, power synchronization mode, free synchronization mode, or non-assist mode, by performing calculation processing as shown in the flowchart in Figure 20, for example.

[0279] The bucket opening / closing mode is a control mode that allows the bucket device 10 to perform operations including changing the open / closed state of a pair of buckets 13, 13 based on a specific operation that has been set in advance. When the control mode is set to bucket opening / closing mode, the controller 70 performs non-synchronized control such as bucket stationary closing control, bucket stationary opening control, and excavation control, which will be described later.

[0280] When the control mode is set to power synchronization mode, the controller 70 performs power synchronization control as described later. When the control mode is set to free synchronization mode, the controller 70 performs free synchronization control as described later.

[0281] The at least one mode switch may include multiple mode switches corresponding to the bucket opening / closing mode, power synchronization mode, free synchronization mode, and non-assist mode, respectively. In this case, the controller 70 may set the control mode to the mode corresponding to the ON operation of any of the multiple mode switches by the operator.

[0282] The controller 70 includes a computer that includes a processing unit and memory. In the modified example shown in Figure 19, the controller 70 includes a lifting value calculation unit 71, an operation state determination unit 72, a bucket weight calculation unit 73, a wire tension determination unit 74, an assist mode determination unit 75, a target pilot pressure calculation unit 76, and a valve command current value calculation unit 77. Each of these functions is realized by the processing unit executing a control program stored in the memory. The valve command current value calculation unit 77 includes a slow operation mode determination unit and a filter processing unit.

[0283] The lifting height calculation unit 71 calculates the lifting height of the first winch rope R1 and the lifting height of the second winch rope R2, respectively, based on the setting data input from the operator setting device 21 to the controller 70, the detection results input from the drum rotation detectors 81 and 82 to the controller 70, and the luffing angle θ of the luffing member 104 input from the luffing member angle detector 22 to the controller 70.

[0284] The setting data input from the operator setting device 21 to the controller 70 may include, for example, specification data including the length of the luffing member 104, and may further include data relating to the relative position of the first winch drum DR1 with respect to the specific part of the luffing member 104, and data relating to the relative position of the second winch drum DR2 with respect to the specific part of the luffing member 104.

[0285] The operation state determination unit 72 determines the lever operation state for the first winch operation lever 51A and the second winch operation lever 53A, respectively, based on the detection results input to the controller 70 from the first lever input detector 51B and the second lever input detector 53B. Specifically, the operation state determination unit 72 determines, based on the detection results, whether the lever operation state is a hoisting operation state, a lowering operation state, or a neutral state.

[0286] The operation state determination unit 72 may determine that the lever operation state is a hoisting operation state if the amount of hoisting operation applied to each of the first winch operating lever 51A and the second winch operating lever 53A is equal to or greater than the threshold amount of hoisting operation. The operation state determination unit 72 may also determine that the lever operation state is a lowering operation state if the amount of lowering operation applied to each of the first winch operating lever 51A and the second winch operating lever 53A is equal to or greater than the threshold amount of hoisting operation. If the operating device is configured such that the remote control valve outputs pilot pressure (secondary pressure) according to the amount of lever operation, the operation state determination unit 72 may acquire the pilot pressure corresponding to the amount of hoisting operation as a correlation value of the amount of hoisting operation and determine the lever operation state based on the pilot pressure, or it may acquire the pilot pressure corresponding to the amount of lowering operation as a correlation value of the amount of lowering operation and determine the lever operation state based on the pilot pressure.

[0287] The operation state determination unit 72 may determine the pedal operation state for the first brake operation pedal 52A and the second brake operation pedal 54A, respectively, based on the detection results input to the controller 70 from the first pedal input detector 52B and the second pedal input detector 54B. Specifically, the operation state determination unit 72 may determine whether the pedal operation state is a brake state or a free state based on the detection results. If the operating device is configured such that the remote control valve outputs pilot pressure (secondary pressure) according to the amount of pedal operation, the operation state determination unit 72 may acquire the pilot pressure corresponding to the amount of pedal operation as a correlation value of the amount of pedal operation and determine the pedal operation state based on the pilot pressure.

[0288] The bucket weight calculation unit 73 calculates the weight of the bucket device 10. Specifically, the bucket weight calculation unit 73 may calculate the weight of the bucket device 10 based on the load value detected by the load value detector 94 at the time an operator performs an input operation on the bucket weight setting device (not shown). The bucket weight setting device may include, for example, a touch panel on a monitor.

[0289] The wire tension determination unit 74 determines whether the bucket device 10 is touching the ground or not based on the load value detected by the load value detector 94 and the bucket weight. For example, the wire tension determination unit 74 may determine that the bucket device 10 is touching the ground if the load value detected by the load value detector 94 at that time is less than or equal to a predetermined first threshold that is less than the bucket weight (for example, less than or equal to 30% of the bucket weight). For example, the wire tension determination unit 74 may determine that the bucket device 10 is not touching the ground if the load value detected by the load value detector 94 at that time is greater than or equal to a predetermined second threshold that is greater than the first threshold (for example, more than or equal to 70% of the bucket weight).

[0290] The assist mode determination unit 75 determines the control mode of the crane 100. Specifically, the assist mode determination unit 75 may determine whether the control mode is bucket opening / closing mode, power synchronization mode, free synchronization mode, or non-assist mode (no control mode) by performing calculation processing as shown in the flowchart of Figure 20, which will be described later.

[0291] The target pilot pressure calculation unit 76 recognizes the current control mode (bucket opening / closing mode, power synchronization mode, free synchronization mode, or non-assist mode) based on the determination result made by the assist mode determination unit 75, and calculates the target pilot pressure to be input to the first control valve 32 and the second control valve 33, respectively, according to the control mode.

[0292] The valve command current value calculation unit 77 calculates command current values ​​to be input to the first dispensing proportional valve 61A, the first retracting proportional valve 61B, the second dispensing proportional valve 63A, and the second retracting proportional valve 63B, respectively, based on the target pilot pressure calculated by the target pilot pressure calculation unit 76. Specifically, for example, the valve command current value calculation unit 77 may calculate the command current values ​​using the target pilot pressure calculated by the target pilot pressure calculation unit 76 and a map representing the relationship between the target pilot pressure and the command current values, as shown in Figure 15, for example. The controller 70 inputs the calculated command current values ​​to the proportional valves 61A, 61B, 63A, and 63B, respectively. The controller 70 may also calculate command current values ​​to be input to various switching valves included in the hydraulic circuit of the crane 100 and input the calculated command current values ​​to the switching valves.

[0293] The slow-operation mode determination unit of the valve command current value calculation unit 77 determines whether to switch between the normal mode and the slow-operation mode. As described above, the slow-operation mode determination unit may switch from the normal mode to the slow-operation mode if, for example, the ground-away condition is met. Also, as described above, the slow-operation mode determination unit may switch from the slow-operation mode to the normal mode if, for example, the ground-away control termination condition is met.

[0294] The filter processing unit of the valve command current value calculation unit 77 performs a filter processing in the ground release control that outputs a processed target value in which the increase in the value per unit time from the limit target value to the winding target value is smaller compared to when no filter processing is applied to the winding target value (for example, step S22 in the flowchart shown in Figure 18).

[0295] Figure 20 is a flowchart showing an example of the calculation process performed by the controller 70 in the modified example.

[0296] In step S101 of Figure 20, the controller 70 determines whether a predetermined bucket opening / closing mode condition is met. The bucket opening / closing mode condition is a condition for determining whether or not to set the control mode to the bucket opening / closing mode. Specifically, for example, the bucket opening / closing mode condition may be that the opening / closing mode switch 90 is in the ON state and the luffing operation lever 55A is not operated.

[0297] If the bucket opening / closing mode conditions are met (YES in step S101), specifically, if the opening / closing mode switch 90 is ON and the luffing operation lever is not operated, the controller 70 sets the control mode to the bucket opening / closing mode in step S102 of Figure 20. If the bucket opening / closing mode conditions are not met (NO in step S101), the controller 70 performs the process in step S103 of Figure 20.

[0298] In step S103 of Figure 20, the controller 70 determines whether a predetermined power synchronization mode condition is met. The power synchronization mode condition is a condition for determining whether or not to set the control mode to power synchronization mode. The power synchronization mode condition may be, for example, the condition that the first winch operating lever 51A is being operated.

[0299] If the power synchronization mode condition is met (YES in step S103), specifically, if the first winch operating lever 51A is operated, the controller 70 sets the control mode to power synchronization mode in step S104 of Figure 20. If the power synchronization mode condition is not met (NO in step S103), the controller 70 performs the process in step S105 of Figure 20.

[0300] In step S105 of Figure 20, the controller 70 determines whether a predetermined free-synchronization mode condition is met. The free-synchronization mode condition is a condition for determining whether or not to set the control mode to free-synchronization mode. The free-synchronization mode condition may be, for example, a neutral free mode and a main hoist free operation. Specifically, the crane 100 has a neutral free mode and a neutral brake mode as control modes. In neutral brake mode, even when the brake pedal is released and not pressed, the winch drum remains connected to the power side. That is, the winch drum will not move without lever operation. By pressing the free switch while the brake pedal is pressed in neutral brake mode, the system enters neutral free mode. By releasing the brake pedal, the winch drum is disconnected from the power side, and the drum rotates due to gravity. "Main hoist free operation" refers to a state where the brake pedal is released, and there is brake pressure such that the drum is disconnected from the power side, meaning the winch drum is driven by the brake pedal. This is detected by a pressure sensor that detects pedal pressure.

[0301] If the free tuning mode condition is met (YES in step S105), specifically, if the winding is neutral and free, the controller 70 sets the control mode to free tuning mode in step S106 of Figure 20. If the free tuning mode condition is not met (NO in step S105), the controller 70 sets the control mode to non-assist mode (no control mode) in step S107 of Figure 20.

[0302] [Bucket Opening / Closing Mode] Next, we will explain the bucket opening / closing mode.

[0303] When the control mode is set to bucket opening / closing mode, the controller 70 performs non-synchronized control such as bucket stationary closing control, bucket stationary opening control, and excavation control.

[0304] Bucket stationary closing control is a control method used in the bucket opening / closing mode to close the buckets 13, 13 while the bucket device 10 is stationary in the air. In bucket stationary closing control, the second winch operating lever 53A is in the neutral position, and the second brake operating pedal 54A is pressed down, meaning that the second winch drum DR2 is braked to prevent its rotation, and a hoisting operation is applied to the first winch operating lever 51A. This allows the first winch rope to be retracted without paying out or retracting the second winch rope, and the bucket device 10 can be operated in the closing direction while maintaining the height of the bucket device 10 in the air.

[0305] Bucket stationary opening control is a control method used in the bucket opening / closing mode to open and operate the buckets 13, 13 while the bucket device 10 is stationary in the air. In bucket stationary opening control, the second winch operating lever 53A is in the neutral position, and the second brake operating pedal 54A is pressed down, meaning that the second winch drum DR2 is braked to prevent its rotation. The first brake operating pedal 52A is then operated to reduce (weaken) the first brake force. This allows the first winch rope R1 to be unfurled and the tension of the first winch rope R1 to be released without unfurling or rewinding the second winch rope, enabling the bucket device 10 to be operated in the opening direction while maintaining its height in the air. This aerial opening operation is used, for example, in soil removal operations, such as unloading soil or other materials held in the closed bucket device 10 onto a destination (e.g., the bed of a truck).

[0306] Excavation control is the control that causes the bucket device 10 to perform an excavation operation in the bucket opening and closing mode. In excavation control, the second winch drum DR2 is left free, and the first winch rope R1 is wound up with the first winch drum DR1, thereby loosening the tension of the second winch rope R2 and causing the bucket device 10 to perform the operation of closing the bucket device 10. As a result, during the process of closing the bucket device 10 in the excavation operation, the bucket device 10 sinks down as the material to be excavated, such as soil, is excavated, and more material to be excavated can be stored inside the bucket device 10.

[0307] [Power Synchronization Mode] Next, we will explain the power synchronization mode. The power synchronization mode is a mode that synchronizes the operation of the first winch drum DR1 and the operation of the second winch drum DR2.

[0308] When the control mode is set to the power synchronization mode, the controller 70 performs power synchronization control such as opening down control, closing down control, opening up control, and closing up control. In the power synchronization mode, the controller 70 controls the operation of the first winch drum DR1 and the operation of the second winch drum DR2 based on the first lever operation applied to the first winch operating lever 51A. Ground release control by the controller 70 is performed when the control mode is set to the power synchronization mode. The lifting operation performed by the bucket device 10 is performed, for example, in the closing up control or the opening up control of the power synchronization control.

[0309] Specifically, when the control mode is set to power synchronization mode and an extension operation is applied to the first winch operating lever 51A, the controller 70 performs the following opening-down control or closing-down control. In 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 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.

[0310] Furthermore, when the control mode is set to power synchronization mode and a hoisting operation is applied to the first winch operating lever 51A, the controller 70 performs the following opening-up control or closing-up control. In 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 closing-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 closed state of the bucket device 10.

[0311] [Free Tuning Mode] Next, we will explain the free tuning mode.

[0312] When the control mode is set to free synchronization mode, the controller 70 performs free synchronization control to adjust the first braking force and the second braking force of the first clutch brake 40 and the second clutch brake 40 based on the amount of operation of the first pedal applied to the first brake operation pedal 52A (pedal operation amount).

[0313] The controller 70 adjusts the first brake force and the second brake force. When the control mode is set to free synchronization mode, a first brake operation that reduces the first brake force is applied to the first brake operation pedal 52A, and the bucket device 10 is in the open state, the controller 70 performs the following opening down control. In this opening down control, the controller 70 adjusts the first brake force and the second brake force so that the bucket device 10 descends by its own weight while maintaining the open state of the bucket device 10. This opening down control performed in response to an operation applied to the brake operation pedal is an example of free synchronization control.

[0314] Furthermore, when the control mode is set to free synchronization mode, a first brake operation that reduces the first brake force is applied to the first brake operation pedal 52A, and the bucket device 10 is in the closed state, the controller 70 performs the following closing down control. In this closing down control, the controller 70 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. This closing down control, which is performed in response to an operation applied to the brake operation pedal, is an example of free synchronization control. A first brake operation that reduces the first brake force is, for example, an operation that reduces the amount of pedal operation (depression amount) applied to the first brake operation pedal 52A.

[0315] The controller 70 may determine the open or closed state of the bucket device 10. That is, the controller 70 may determine whether the bucket device 10 is in an open state or a closed state. The controller 70 may determine the open or closed state of the bucket device 10 based on a first rotation amount ωm and a second rotation amount ωa.

[0316] [Modifications] The second technology of this disclosure is not limited to the third embodiment described above. The second technology of this disclosure includes, for example, the following modifications.

[0317] (A) Regarding the specifications of the crane, the crane according to the third embodiment shown in Figure 1 does not have a jib and struts, but the specifications of the crane are not limited to those shown in Figure 1. The crane according to the disclosure may be a luffing crane equipped with a jib, front struts and rear struts, or it may be a fixed jib crane equipped with a jib and one strut. Furthermore, the crane according to the disclosure may be a crane equipped with a mast instead of a gantry (for example, a large crane).

[0318] In the third embodiment described above, 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.

[0319] (B) With respect to the winch rope and winch drum, in the third embodiment, the first winch rope R1 is the opening / closing rope, the second winch rope R2 is the support rope, the first winch drum DR1 is the opening / closing drum, and the second winch drum DR2 is the support drum, but these may be reversed. That is, the first winch rope R1 may be the support rope, the second winch rope R2 may be the opening / closing rope, the first winch drum DR1 may be the support drum, and the second winch drum may be the opening / closing drum.

[0320] (C) Regarding the bucket control device: In the third embodiment described above, the bucket control device 200 is provided on the crane 100. However, the bucket control device in this disclosure does not necessarily have to be provided on a construction machine such as a 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.

[0321] (D) Operating devices The operating devices according to this disclosure may be appropriately selected depending on the type of first and second winches and their drive devices. For example, the lever input detectors 51B and 53B of the first winch operating device 51 and the second winch operating device 53 shown in Figures 2 and 3, and the pedal input detectors 52B and 54B of the first brake operating device 52 and the second brake operating device 54 may each be replaced with a device that includes a remote control valve that outputs pilot pressure corresponding to the operation and a pressure sensor that detects said pilot pressure. In this case, proportional valves 61A and 61B may be interposed between the remote control valve of the first winch operating device 51 and a pair of pilot ports of the first control valve, respectively, and proportional valves 63A and 63B may be interposed between the remote control valve of the second winch operating device 53 and a pair of pilot ports of the second control valve 33, respectively. Furthermore, the proportional valve 62 may be interposed between the remote control valve of the first brake operating device 52 and the first clutch brake 40, and the proportional valve 64 may be interposed between the remote control valve of the second brake operating device 54 and the second clutch brake 40.

[0322] (E) With respect to the winch, the first winch and the second winch according to this disclosure may be, for example, electric winches. In this case, the hydraulic circuit shown in Figure 3 can be replaced with an electrical circuit (for example, a circuit including an inverter) that drives the electric winch.

[0323] (F) Ground-away control In the third embodiment described above, the ground-away control includes obtaining a processed target value by applying the filtering process to the winding target value, but the ground-away control in this disclosure is not limited to the third embodiment. In the ground-away control in this disclosure, for example, the controller may obtain a processed target value in which the change in the winding target value is smoothed by performing rate limiter processing on the winding target value corresponding to the amount of winding operation. The rate limiter processing is a process that suppresses the amount of change in the target pilot pressure per unit time to a set value or less.

[0324] The controller 70 may store a predetermined map to limit the amount of increase in the winding speed per unit time in the ground-away control, and may perform the ground-away control using the map. Specifically, it is as follows.

[0325] The controller 70 may store a predetermined function (map) for performing the ground separation control. In this case, the controller 70 may calculate an output value y by inputting an input value x to the function, and use the calculated output value y to perform processing to obtain a post-process target value. The function has the characteristic that the output value y increases as the input value x increases. The input value x may be, for example, the elapsed time since the ground separation condition was met. In this case, the controller 70 can obtain an output value y that gradually increases with the passage of time. The function may be, for example, a sigmoid function, a cycloid function, or any other function that includes a portion in which the output value y increases as the input value x increases.

[0326] Figure 21 is a graph showing an example of the temporal change of the post-processing target value (target pilot pressure) obtained using a predetermined function, and corresponds to the graph in Figure 13B. In the specific example shown in Figure 21, the function is set to output a value of zero or near zero as the output value y when the ground-away condition is met (time t2), to output a value of 1 or near 1 as the output value y when a predetermined time has elapsed (time t3), and to output a value of y that gradually increases from zero or near zero to 1 or near 1 from the time the ground-away condition is met until the predetermined time. In the specific example shown in Figure 21, the function is a sigmoid function or a cycloid function. When the ground-away condition is met, the controller 70 obtains a value obtained by multiplying the winding target value (maximum target value) at time t2 by the output value y as the post-processing target value. Then, from time t2 to time t3, the controller 70 sequentially acquires a post-processing target value obtained by multiplying the winding target value (maximum target value) at that point in time by the output value y for each control cycle. Based on the acquired post-processing target value, the controller 70 operates the first winch drum DR1 and the second winch drum DR2. This effectively mitigates the impact applied to the crane 100 when the bucket device 10 leaves the ground.

[0327] Figure 22 is a graph showing another example of the temporal change in the post-processing target value (target pilot pressure) obtained using a predetermined function. The function in the specific example shown in Figure 22 differs from the specific example shown in Figure 21 in that the output value y is set to a constant value during a predetermined time period between time t2 and time t3 (the area enclosed by the dashed circle in Figure 22). Note that there may be multiple time periods between time t2 and time t3 during which the output value y is constant.

[0328] The controller 70 may store a predetermined table (map) for performing the ground-lift control. The table may be, for example, a lookup table for assigning output values ​​to input values. The input value may be, for example, the amount of the hoisting operation, the current value corresponding to the amount of the operation, the winding target value, or the elapsed time from the time when the ground-lift condition is met. The output value may be, for example, a post-processing target value (e.g., target pilot pressure). The controller 70 can use the input value and the table to obtain the post-processing target value which gradually increases over time. The controller 70 operates the first winch drum DR1 and the second winch drum DR2 based on the obtained post-processing target value. This effectively mitigates the impact applied to the crane 100 when the bucket device 10 lifts off the ground.

[0329] (G) Filtering Process In the third embodiment described above, the filtering process is a low-pass filter process. However, the filtering process in this disclosure is not limited to a low-pass filter process, and may be other filtering processes that can output a processed target value in which the increase in the value per unit time from the limit target value to the winding target value is smaller compared to the case in which no filtering process is applied to the winding target value.

[0330] (H) Regarding the winding target value, in the third embodiment described above, the winding target value is the target pilot pressure. However, the winding target value in this disclosure may be, for example, the target value (target speed) of the winding speed of the first winch rope R1 and the second winch rope R2, or the target value (target speed) of the winding rotation speed of the first winch drum DR1 and the second winch drum DR2. Each of these target speeds is a target value that increases in proportion to the increase in the amount of operation of the winding operation.

[0331] As described above, the second technology, including the third embodiment of the present disclosure, provides a technology that can mitigate the impact on construction machinery when a bucket device rises and leaves the ground. The second technology of the present disclosure includes the following first to seventh embodiments.

[0332] A bucket control device according to the first aspect of the second technology 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 to which the first winch rope and the second winch rope are connected and which can be raised and lowered in accordance with the operation of the first winch drum and the operation of the second winch drum; and an operating device for receiving a hoisting operation to raise the bucket device, wherein the bucket control device includes a controller that performs ground-away control, which operates the first winch drum and the second winch drum such that the increase in winding speed per unit time is smaller than the increase in winding speed per unit time corresponding to the amount of the hoisting operation, when predetermined ground-away conditions for determining when the bucket device leaves the ground are met.

[0333] In the first embodiment, the ground-separation control described above is performed when the bucket device rises and leaves the ground, thereby mitigating the impact on the construction machine.

[0334] A bucket control device according to a second aspect of the second technology may further include the following configuration in addition to that of a bucket control device according to a first aspect. That is, in a bucket control device according to a second aspect, the controller calculates a winding target value, which is a target value that increases in proportion to the increase in the amount of operation of the hoisting operation, and in the ground release control, the controller may operate the first winch drum and the second winch drum based on a processed target value obtained by applying a predetermined filter process to the winding target value.

[0335] In the second embodiment, the controller operates the first winch drum and the second winch drum based on a processed target value obtained by applying the filtering process to the winding target value, thereby effectively mitigating the impact applied to the construction machine when the bucket device leaves the ground.

[0336] A bucket control device according to a third aspect of the second technology preferably further comprises the following configuration in addition to the bucket control device according to the first or second aspect. That is, in the bucket control device according to the third aspect, it is preferable that the controller performs limiting control to limit the winding speed of the first winch rope and the second winch rope to a speed smaller than the maximum winding speed corresponding to the maximum amount of the winding operation when the operating device receives the winding operation while the bucket device is in contact with the ground.

[0337] In the third embodiment, when the operating device receives the hoisting operation while the bucket device is in contact with the ground, the limiting control described above is performed, so that the winding speed immediately before the ground-away control is started, that is, immediately before the bucket device leaves the ground, is kept lower than the maximum winding speed. As a result, the controller can start the ground-away control, which is performed after the limiting control, at a speed lower than the maximum winding speed, so that the bucket device leaves the ground slowly during the limiting control and the ground-away control.

[0338] A bucket control device according to a fourth aspect of the second technology preferably further comprises the following configuration in addition to the bucket control device according to the third aspect. That is, in the bucket control device according to the fourth aspect, the controller preferably calculates a target winding value which is a target value that increases in proportion to the increase in the amount of operation of the winding operation, limits the target pilot pressure to a limit target value smaller than the winding target value in the limit control, operates the first winch drum and the second winch drum based on the limit target value, and in the ground release control, obtains a processed target value as the target pilot pressure which gradually increases from the limit target value to the winding target value by applying a predetermined filter process to the winding target value, and operates the first winch drum and the second winch drum based on the obtained target pilot pressure.

[0339] A bucket control device according to a fifth aspect of the second technology may further include the following configuration in a bucket control device according to a first or third aspect. That is, in a bucket control device according to a fifth aspect, the controller stores a predetermined map for limiting the amount of increase per unit time of the winding speed in the ground-away control, and may perform the ground-away control using the map.

[0340] A construction machine according to the sixth aspect of the second technology comprises the first winch drum, the second winch drum, the bucket device, the operating device, and a bucket control device according to any one of the first to fifth aspects.

[0341] In the sixth embodiment, the ground-lift control described above is performed when the bucket device rises and leaves the ground, thereby mitigating the impact on the construction machine.

[0342] A bucket control method according to a seventh aspect of the second technology is a control method using a bucket control device according to any one of the first to fifth aspects, wherein when a predetermined ground separation condition for determining whether the bucket device is lifted off the ground is met, the controller operates the first winch drum and the second winch drum such that the amount of increase per unit time of the winding speed is smaller than that of the winding operation corresponding to the amount of the winding operation.

[0343] In the seventh embodiment, the ground-separation control described above is performed when the bucket device rises and leaves the ground, thereby mitigating the impact on the construction machine.

Claims

1. A bucket control device for a construction machine comprising: a machine body; a luffing member that can be raised and lowered relative to the machine body; a first winch drum for paying out and winding a first winch rope hanging from the luffing member; a second winch drum positioned differently from the first winch drum for paying out and winding a second winch rope hanging from the luffing member; and a bucket device to which the first winch rope and the second winch rope are connected, and which has a bucket that can be opened and closed in accordance with the operation of the first winch drum and the operation of the second winch drum, wherein the bucket control device comprises a controller configured to perform luffing synchronization control to maintain the open and closed state of the bucket by adjusting one or both of the amount of payout of the first winch rope and the amount of payout of the second winch rope in accordance with the angle change of the luffing member during the luffing operation of the luffing member.

2. The bucket control device according to claim 1, wherein the controller is configured to adjust one or both of the payout amount of the first winch rope and the payout amount of the second winch rope based on the amount of change of a first distance from the first winch drum to a predetermined first part of the luffing member, which changes in accordance with the angle change, and the amount of change of a second distance from the second winch drum to a predetermined second part of the luffing member, which changes in accordance with the angle change.

3. The bucket control device according to claim 1 or 2, wherein the construction machine further comprises a luffing control device which is an operating device that receives luffing operations for luffing the luffing member, and the controller is configured to perform luffing synchronization control when the luffing control device receives the luffing operation.

4. The bucket control device according to any one of claims 1 to 3, wherein the construction machine further comprises an operating device for receiving a hoisting operation to raise the bucket device, and the controller is configured to perform ground-away control by operating the first winch drum and the second winch drum such that the amount of increase per unit time of the winding speed is smaller than that of a winding operation corresponding to the amount of the hoisting operation when predetermined ground-away conditions for determining when the bucket device leaves the ground are met.

5. The bucket control device according to claim 4, wherein the controller calculates a target winding value which increases in proportion to the increase in the amount of operation of the winding operation, and in the ground release control, operates the first winch drum and the second winch drum based on a processed target value obtained by applying a predetermined filter process to the winding target value.

6. The bucket control device according to claim 4 or 5, wherein the controller is configured to perform limiting control to limit the winding speed of the first winch rope and the second winch rope to a speed less than the maximum winding speed corresponding to the maximum amount of the winding operation when the operating device receives the winding operation while the bucket device is in contact with the ground.

7. The bucket control device according to claim 6, wherein the controller calculates a target winding value which is a target value that increases in proportion to the increase in the amount of operation of the winding operation; in the limit control, limits the target pilot pressure to a limit target value smaller than the winding target value, and operates the first winch drum and the second winch drum based on the limit target value; and in the ground release control, obtains a processed target value as the target pilot pressure which gradually increases from the limit target value to the winding target value by applying a predetermined filter process to the winding target value, and operates the first winch drum and the second winch drum based on the obtained target pilot pressure.

8. The bucket control device according to any one of claims 4 to 7, wherein the controller stores a predetermined map for limiting the amount of increase per unit time of the winding speed in the ground-away control, and is configured to perform the ground-away control using the map.

9. A construction machine comprising: the machine body; the luffing member; the first winch drum; the second winch drum; the bucket device; and the bucket control device according to any one of claims 1 to 8.

10. A bucket control method using a bucket control device according to any one of claims 1 to 8, wherein the controller maintains the open / closed state of the bucket by adjusting one or both of the payout amount of the first winch rope and the payout amount of the second winch rope in accordance with the change in angle of the luffing member during the luffing operation of the luffing member.

11. A bucket control method according to claim 10, the method comprising the controller operating the first winch drum and the second winch drum such that when a predetermined ground-away condition for determining whether the bucket device is lifted off the ground is met, the increase in winding speed per unit time is smaller than that of a winding operation corresponding to the amount of winding operation.

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