Crane equipped with cable reel

Abstract

To provide a crane equipped with a vertical-winding type cable reel for supplying power to a hoisting tool suspended from the crane, which has improved cable reel dimensions, ease of maintenance, and torque control performance.SOLUTION: There is provided a crane equipped with a cable reel that uses a multi-pole motor for a reel drive motor DM, and adopts a direct drive method that directly drives an axis SH of a cable drum CD of a cable reel RE without a reducer, and has the function of increasing / decreasing the torque of the reel drive motor DM so that the winding torque of the cable reel RE is increased above the torque value when stopped only when a hoisting device GB is accelerating for winding up and when the hoisting device GB is decelerating for lowering, based on the operating information of a control device that controls the up and down movement of the hoisting device GB.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a crane in which a cable reel is installed on a club trolley, and the torque generation source of the cable reel for vertical winding for supplying power to a lifting tool suspended by a lifting device of the crane is an electric motor, and the electric motor always generates torque in the winding direction, so as to follow the up-and-down movement of the lifting tool. The present invention relates to a crane equipped with a cable reel of this type.

Background Art

[0002] For a vertical winding cable reel for supplying power to a lifting tool suspended by a crane, the vertical cable wound around the cable reel is tensioned by its own weight, and the cable reel rotates the cable drum of the cable reel with a strong torque to wind up the cable against this tension. Therefore, the cable is severely damaged due to the tension on the huge cable, and technologies for mitigating this are required. For example, they are proposed in Patent Documents 1 to 3, and further mitigation of the cable burden is also required. Furthermore, the space on the club trolley where the cable reel for lifting tool power supply is arranged is narrow, and a compact cable reel with an improved protruding dimension of the cable reel is required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, cable reels that use an electric motor as the source of torque for winding the cable transmit torque by placing a reduction gear such as a gearbox or chain / sprocket between the electric motor and the cable drum. The torque setting value of the electric motor in a cable reel is set by adding the torque required to wind the cable and the reduction efficiency of the reduction gear. In that state, when the cable is pulled out, the reverse rotation efficiency of the reduction gear during pulling is added to the set value of the motor's torque, which is the sum of the reduction efficiency. This torque is then applied to the cable as tension, resulting in a problem where the reduction efficiency is applied to the cable as a double excess torque during cable pulling. To mitigate this problem, various measures have been taken, such as employing expensive planetary gear reducers with better reverse rotation efficiency or using bevel gears, but these have not provided a fundamental solution. Furthermore, these gearboxes were large in size, which also presented the problem of increasing the size of the drive unit of the cable reel. Furthermore, despite being an electrical device, the cable reel had the added inconvenience of requiring periodic mechanical maintenance, such as changing the oil in the gearbox. Furthermore, as the load factor of the reduction gear decreases, the reduction efficiency also deteriorates. This forced the adoption of a small reduction gear with no safety margin, resulting in a design that sacrificed durability margins and pushed the limits to the absolute minimum. Incidentally, the cable reel described in Patent Document 3 focuses on the fact that the relationship between the winding angle and the load torque becomes slightly nonlinear due to the switching of each layer of the wound cable, and proposes controlling this slight torque change. However, the large deceleration efficiency applied in two stages hinders the transmission of this slight torque change, resulting in a rough torque change. The problem was that all they could do was transmit the information.

[0005] The torque required to operate a cable reel fluctuates depending on whether it is accelerating, decelerating, winding, or unwinding. However, since a cable reel is merely a device that follows the movement of the suspension equipment suspended from the wire drum, it lacks the autonomy to determine its own operation and therefore could not control the torque required for the cable reel itself.

[0006] In view of these problems, the present invention aims to provide a crane equipped with a vertical winding cable reel for supplying power to a lifting device suspended from the crane, with improvements in the dimensions of the cable reel, maintainability, and torque control performance. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a crane equipped with a cable reel, which is a vertical winding type cable reel for supplying power to a lifting device suspended from a crane, wherein the cable is wound onto or unwound from the cable drum of the cable reel in conjunction with the vertical movement of the lifting device by generating torque in the winding direction with a reel drive motor, The reel drive motor uses a multi-pole motor and employs a direct drive system that directly drives the shaft of the cable drum of the cable reel without a reduction gear. Based on the operation information of the control device that controls the vertical movement of the suspension device, The system is characterized by having a function that controls the torque of the reel drive motor to increase or decrease only when the lifting device is being accelerated upwards or when the lifting device is being decelerated downwards, so that the winding torque of the cable reel is greater than the torque value at the time of stopping.

[0008] In this case, based on the operation information of the control device that controls the vertical movement of the suspension device, The system can have a function to control the torque of the reel drive motor so that the winding torque of the cable reel is reduced to the torque value at the time of stopping, both when the suspension device is being reeled up and when the suspension device is being reeled down and when it is being accelerated.

[0009] Furthermore, based on the operation information of the control device that controls the vertical movement of the suspension device, The system can have a function to control the torque of the reel drive motor so that the winding torque of the cable reel is the same as the torque value when the suspension device is being retracted at a constant speed.

[0010] Furthermore, based on the operation information of the control device that controls the vertical movement of the suspension device, The system may have a function to control the torque of the reel drive motor so that the winding torque of the cable reel is reduced to a value lower than the torque value at the time of stopping when the suspension device is being lowered at a constant speed. [Effects of the Invention]

[0011] According to the present invention, a crane equipped with a cable reel employs a direct drive system using a multi-pole motor for the reel drive motor, eliminating the need for a reduction gear, thereby reducing the dimensions of the drive unit and minimizing the protrusion of the cable reel. This compact design of the cable reel allows for more efficient use of space on the crane's traction, and eliminates the mechanical maintenance element of oil changes for the reduction gear during periodic maintenance of the cable reel, thereby improving the maintainability of the cable reel. Furthermore, by eliminating the reduction gear, it became possible to transmit torque directly from the reel drive motor to the cable drum. As a result, the reduction efficiency of the reduction gear is reduced for the cable reel. By eliminating factors that hinder torque control, torque control performance can be improved. Consequently, the durability issues of gearboxes with low safety factors set to optimize reduction efficiency are eliminated, and the reliability of cable reel devices and the cables wound onto them can be significantly improved.

[0012] When demonstrating the performance enabling fine torque control, it is necessary to determine how the cable reel operates according to the operating status of the wire drum suspending the spreader. When the crane is in the hoisting acceleration state and the lowering deceleration state, increase the torque of the reel drive motor. When the crane is in the hoisting deceleration state and the lowering acceleration state, decrease the torque of the reel drive motor. When the crane is lowering, slightly decrease the torque of the reel drive motor, thereby reducing the burden on the cable and extending the life of the cable.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic explanatory drawing of a crane to which the cable reel for crane spreader power supply of the present invention is applied. [Figure 2] It is an explanatory drawing of the structure of a cable reel excluding the reduction gear efficiency. [Figure 3] It is an explanatory drawing of the influence of the reduction gear efficiency on the drawing torque of the cable reel. [Figure 4] It is an explanatory drawing of the relationship between the load factor of the reduction gear and the reduction gear efficiency. [Figure 5] It is an explanatory drawing when the drawing torque is suppressed by the boost torque during winding. [Figure 6] It is an explanatory drawing of the control method when the reduction efficiency is excluded.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the crane provided with the cable reel of the present invention will be described based on the drawings.

[0015] FIG. 1 is a schematic explanatory drawing of a crane provided with the cable reel of the present invention. A spreader GB completely supported by a wire rope WR from a wire drum WD on a crab trolley TR of a crane CR is suspended, and the spreader GB is moved up and down only by the rotational force of the wire drum WD. Cable CA hangs from cable reel RE, positioned next to wire drum WD, in a constantly taut state, is secured with fixing bracket FS, and supplies power to suspension device GB. The cable reel RE constantly generates winding torque in the winding direction, keeping the cable CA constantly under tension. When the suspension device GB is lowered, the cable wrapped around the cable reel RE is pulled out while maintaining tension due to the winding torque of the cable reel RE. When the suspension device GB is raised, the cable CA is wrapped around the cable reel RE while maintaining tension due to the winding torque of the cable reel RE. At this time, the winding torque of the cable reel RE is set to a weak torque that is only enough to support the cable CA and the fixing bracket FS, and does not support the load of the suspension device, but is only weak enough to follow the up and down movement of the suspension device GB.

[0016] Figure 2 shows an embodiment of a crane equipped with the cable reel of the present invention. Cable CA, wound around cable drum CD, is connected to slip ring SR via a hollow shaft SH from cable drum CD, and is electrically connected to the rotating cable CA from fixed wiring connected to carbon brush CB, which contacts slip ring SR. Then, the reel drive motor DM, connected to the hollow shaft SH, generates a predetermined rotational torque controlled by the detection of the rotational position sensor PG, which is transmitted to the cable drum CD via the hollow shaft SH, generating the torque to wind up the cable CA. Conventionally, a reduction gear was interposed between the reel drive motor DM and the hollow shaft SH, allowing the use of a general-purpose reel drive motor DM and brake BR with high rotational speed and low rated torque. Due to the high rotational speed, it was also possible to use an induction motor for the reel drive motor DM, which had the advantage of being constructed with low-cost components. However, when a planetary reduction gear was used, the reduction gear, reel drive motor, and brake were arranged in series from the hollow shaft SH, resulting in a large protrusion at the rear of the cable reel. When bevel gears were used, the reduction gear, reel drive transmitter, and brake were arranged at a right angle upward or to the side from the hollow shaft SH, resulting in a large upward or lateral protrusion. In this embodiment, a multi-pole synchronous motor with a permanent magnet rotor that enables a high torque rated output at low rotational speeds is used for the reel drive motor DM, and a large, high-torque brake is employed for the brake, making it possible to directly drive the hollow shaft SH without using a reduction gear. This eliminates the factor where the reduction efficiency of the gearbox hindered torque control of the cable reel, and also eliminates the protrusion of the drive unit that extended significantly to the rear, above, or to the side of the cable reel, enabling effective use of the dimensions on the narrow club trolley TR where the cable reel RE is located.

[0017] Despite the fact that the cable reel RE is an electrical device requiring inspection by various electrical engineers for routine maintenance, including replacing carbon brushes CB, managing and adjusting slip ring wear, checking for damage to cables CA, managing torque control constants, and replacing data storage batteries, the only maintenance required was the oil change of the gearbox, which needed to be performed by a mechanical engineer. In this cable reel RE, which eliminates the gearbox, the only mechanical maintenance element—periodic oil replacement for the gearbox—was eliminated, and by leaving only electrical maintenance items, maintainability was improved.

[0018] The effect of gearbox efficiency on the cable reel's pulling torque will be explained using Figure 3. The winding torque HT required when winding up cable CA is calculated by multiplying the weight per unit length of cable CA by the hanging length L, adding the weight of the fixing bracket FS, and multiplying the hanging weight by the distance from the center position of cable drum CD to the hanging position of cable CA. This results in the cable load torque CT, which is the torque obtained by adding the acceleration torque AT, which is used to accelerate the inertial force of rotating objects such as cable drum CD and linearly moving objects such as cable CA, and the cable load torque CT. At this time, in order to generate the winding torque HT required for winding the cable CA, the reel drive motor DM must be generated with the torque MT obtained by adding the torque for the reduction gear efficiency ηG. When the motor torque MT is generated, which includes the torque corresponding to the reduction gear efficiency ηG, and the suspension device GB is lowered, pulling the cable CA, the torque corresponding to the reduction gear reverse efficiency ηR is further added, generating a pull-out torque RT. At this time, the cable CA is subjected to both the reduction gear efficiency ηG and the reduction gear reverse efficiency ηR, and the pull-out torque RT at this time becomes approximately twice the required torque due to the double reduction gear efficiency, and the excessive tension caused by the large pull-out torque RT was a factor in damaging the cable CA. The torque generated by such a gearbox efficiency accounts for a large proportion of the motor's torque control, and even when attempting to perform fine torque control, it is buried within the gearbox losses. As a result, only rough torque control with coarse resolution was possible.

[0019] By the way, as shown in Figure 4, when the load factor LG transmitted by the reducer decreases, the reducer efficiency ηG deteriorates accordingly. Therefore, in cable reels where the reducer efficiency ηG is doubled and affects the cable, it is necessary to make the reducer highly efficient. However, it is not possible to use a robust reducer by increasing the safety factor of the reducer, and the reducer becomes a bottleneck, making it difficult to use a robust cable reel. They were unable to manufacture the cable reel. Furthermore, they were faced with the necessity of adopting expensive gearboxes with high reverse rotation efficiency, such as planetary gearboxes.

[0020] Thus, as a way to mitigate the excessive torque RT caused by the double reduction gear efficiency becoming a load, Patent Document 1, as shown in Figure 5, increases the torque value upon receiving a signal that the crane lifting device is hoisting, creating a boost torque BT. When hoisting is not occurring, i.e., when stopped or during unwinding, the motor torque MT is obtained by subtracting the acceleration torque AT, which corresponds to the reduction gear efficiency ηG. This allows the cable, which has slackened due to load swing while stopped, to be slowly wound up without acceleration, and during unwinding, the unwind torque RT is suppressed to an excess torque of only the reduction gear reverse efficiency ηR. However, the excessive tension on the cable CA due to the gearbox reverse rotation efficiency ηR could not be eliminated.

[0021] To prevent excessive tension on the cable due to the load associated with the reduction gear efficiency, the cable reel of this crane employs a direct drive system that does not use a reduction gear, as shown in Figure 2. Consequently, factors that hinder torque transmission due to gearbox efficiency are eliminated, enabling precise torque control. However, the cable reel RE follows the lifting device GB which moves up and down on the wire drum WD, and is not a mechanism that operates independently. Therefore, it is difficult for the cable reel RE itself to adjust its torque. By changing the torque of the cable reel RE based on the operating information of the winding control device that operates the wire drum WD, precise control becomes possible.

[0022] The required torque for each state of the cable reel RE will be explained using Figure 6. First, the cable load torque CT is calculated by multiplying the weight per unit length of the cable by the sag length L, adding the weight of the fixing bracket FS to calculate the sag weight, and then multiplying that sag weight by the distance between the support points from the center of the cable drum CD to the cable sag position. Therefore, the cable load torque CT is a value that changes with the sag length L, and as described in Patent Documents 1 and 3, it can be appropriately changed by changing the motor torque MT based on the detected value of the rotational position detector PG equipped on the reel drive motor DM. The required winding torque HT is obtained by adding the acceleration torque AT, which accelerates the inertial force of the rotating parts such as the cable drum CD and the moving parts such as the cable, to the cable load torque CT. The torque value obtained by adding the torque due to the bearing efficiency ηB, which is a small loss in the bearing part, to this is the winding acceleration torque MT1 required as the amount of torque generated by the reel drive motor DM during winding acceleration. Then, the value obtained by subtracting the acceleration torque AT from this winding acceleration torque MT1 is the steady-state winding torque MT2 required when the cable winding has finished accelerating and is winding at a constant speed. Then, the torque value obtained by subtracting the deceleration torque DT, which reduces the inertial force of the rotating parts such as the cable drum CD and the moving parts such as the cable CA, from the steady-state winding torque MT2 is the winding deceleration torque MT3 required during deceleration during winding. Furthermore, the stopping torque MT4 required when the machine is stopped will have the same torque value as the steady-state winding torque MT2.

[0023] When operating in the pull-out direction (PD), the acceleration torque (AT), deceleration torque (DT), and bearing efficiency (ηB) all act in the opposite direction to when winding (RU). Therefore, during acceleration when pulling out, the torque value obtained by subtracting the acceleration torque AT and bearing efficiency from the cable load torque CT becomes the torque MT5 during acceleration when pulling out at a constant speed. The torque at that time is the cable load torque CT minus the bearing efficiency ηB, which becomes the steady-state torque MT6. Adding the deceleration torque DT to the steady-state torque MT6 gives the deceleration torque MT7. Furthermore, in all states from MT1 to MT7 shown in Figure 6, by slightly adding a certain torque value, cable sway caused by external disturbances such as load sway can be eliminated, and a constant tension can be maintained.

[0024] The state in which the required torque of the cable reel RE is shown in Figure 6 is determined by the control information of the hoisting speed control device (inverter control device, etc.) that controls the hoisting motor that drives the wire drum WD. If the hoisting speed control device is accelerating hoisting, it is determined to be the hoisting acceleration torque MT1; if the hoisting speed control device is operating at a constant hoisting speed, it is determined to be the hoisting steady-state torque MT2; if the hoisting speed control device is decelerating hoisting, it is determined to be the hoisting deceleration torque MT3; if the hoisting speed control device is stopped, it is determined to be the stopping torque MT4; if the hoisting speed control device is accelerating downwinding, it is determined to be the pull-out acceleration torque MT5; if the hoisting speed control device is operating at a constant downwinding speed, it is determined to be the pull-out steady-state torque MT6; and if the hoisting speed control device is decelerating downwinding, it is determined to be the pull-out deceleration torque MT7.

[0025] At this time, when actually driving a direct-drive cable reel without a gearbox, the reference value for torque setting is set to the standard torque value of the reel drive motor by adding a small amount of torque to the cable load torque CT plus the torque due to bearing efficiency, which is the steady-state winding torque MT2 and the stopping torque MT4, in order to eliminate cable wobble due to the aforementioned disturbances and maintain a constant tension. Furthermore, when the hoisting speed control device is accelerating the hoisting or decelerating the hoisting, it outputs an instruction to increase the torque value to the cable reel RE, thereby eliminating slack in the cable CA. Furthermore, when the hoisting speed control device is decelerating during hoisting or accelerating during lowering, it can reduce the load on the cable CA by outputting a torque reduction instruction to the cable reel RE. Furthermore, during lowering operation, the hoisting speed control device sends a torque reduction command to the cable reel RE equal to twice the torque value of the bearing efficiency, thereby further reducing the load on the cable.

[0026] The direct drive system, which eliminates the gearbox, removes the excessive load caused by the gearbox efficiency ηG and gearbox reverse rotation efficiency ηR that were generated in the gearbox section. As a result, the only factor hindering torque transmission is the bearing efficiency ηB of the bearing section, which can be significantly reduced. Incidentally, if the structure is changed from the cantilever structure shown in Figure 2, in which the cable drum CD is supported by a bearing BB on only one side, to a double-support structure in which bearing BBs are placed on both sides of the cable drum CD, the value of the bearing efficiency ηB can be further improved, enabling more ideal torque control.

[0027] The crane equipped with the cable reel of the present invention has been described above based on its embodiments. However, the present invention is not limited to the configuration described in the embodiments, and its configuration can be modified as appropriate without departing from the spirit of the invention. [Industrial applicability]

[0028] According to the crane equipped with the cable reel of the present invention, by employing a direct drive system that eliminates the reduction gear by using a multi-pole motor, not only is the size reduced by eliminating the reduction gear, but the drawback of the reduction gear's efficiency becoming a double factor in overloading the cable is also eliminated, thus overcoming the disadvantage of cable reels where this drawback is a bottleneck that prevents increasing the safety factor of the reduction gear, and also eliminating the factors that hinder torque transmission between the motor and the cable. The elimination of the gearbox enables precise torque control, making it highly valuable for industrial applications. [Explanation of symbols]

[0029] CR Crane TR Club Trolley WD Wire Drum WR wire rope GB hanging equipment RE Cable Reel CA Cable FS Fixing Bracket L Hanging length CD Cable Drum SH shaft (hollow shaft) DM reel-driven electric motor PG Rotational Position Detector BR Brake BB bearing TB terminal block SR slip ring CB Carbon Brush HT winding torque MT electric motor torque ηG Gearbox Efficiency ηR Gearbox reverse rotation efficiency RT pull-out torque LG reducer load factor BT Boost Torque AT acceleration torque CT cable load torque DT reduction torque V speed t time RU winding PD drawer ηB bearing efficiency MT1 Torque during winding acceleration MT2 steady-state winding torque MT3 Torque during winding deceleration MT4 Torque at Stop MT5 Torque during acceleration MT6 Extraction steady-state torque MT7 Torque during deceleration

Claims

1. A crane equipped with a vertical winding cable reel for supplying power to a lifting device suspended from a crane, wherein the structure generates torque in the winding direction by a reel-driven electric motor, thereby winding or unwinding the cable onto the cable drum of the cable reel in conjunction with the vertical movement of the lifting device, The reel drive motor uses a multi-pole motor and employs a direct drive system that directly drives the shaft of the cable drum of the cable reel without a reduction gear. Based on the operation information of the control device that controls the vertical movement of the suspension device, The system has a function to control the torque of the reel drive motor so that the winding torque of the cable reel is increased above the torque value at the time of stopping, only when the suspension device is being accelerated upwards or when the suspension device is being decelerated downwards. A crane equipped with a cable reel, characterized by the following features.

2. Based on the operation information of the control device that controls the vertical movement of the suspension device, The system has a function to control the torque of the reel drive motor so that the winding torque of the cable reel is reduced to the torque value at the time of stopping, both when the suspension device is being reeled up and when the suspension device is being reeled down and when it is being accelerated. A crane equipped with a cable reel as described in feature 1.

3. Based on the operation information of the control device that controls the vertical movement of the suspension device, The system has a function to control the torque of the reel drive motor so that the winding torque of the cable reel is the same as the torque value when the suspension device is being retracted at a constant speed. A crane equipped with a cable reel according to claim 1 or 2.

4. Based on the operation information of the control device that controls the vertical movement of the suspension device, The system has a function to control the torque of the reel drive motor so that the winding torque of the cable reel is reduced to the torque value at the time of stopping when the suspension device is being lowered at a constant speed. A crane equipped with a cable reel according to claim 1, 2, or 3.

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