Crane 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 equipped with a cable reel mounted on a club trolley, in which an electric motor serves as the torque generating source for the vertical winding cable reel to supply power to a hoisting device suspended by the crane's hoisting device, and which is equipped with a cable reel that always generates torque in the winding direction to follow the up and down movement of the hoisting device. [Background technology]

[0002] In a vertical winding cable reel for supplying power to a hoisting device suspended from a crane, the vertical cable being wound up on the cable reel is subjected to tension due to the cable's own weight, and the cable reel rotates the cable drum of the cable reel with a torque strong enough to overcome this tension and wind up the cable. Therefore, the cable is severely damaged by the huge tension on the cable, and technology to alleviate this is required, and has been proposed in Patent Documents 1 to 3, for example, and further reduction in cable burden is also required. Furthermore, the space above the club trolley on which the cable reel for power supply to the hoisting equipment is arranged is narrow, and there is a demand for a compact cable reel with improved protruding dimensions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-260684 A [Patent Document 2] JP 2018-162147 A [Patent Document 3] JP 2021-66553 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, cable reels that use an electric motor as the source of cable winding torque transmit torque through a reduction gear such as a reducer or chain sprocket placed between the motor and the cable drum. The torque setting value of the cable reel's electric motor is set by adding the torque required to wind the cable and the reduction efficiency of the reduction gear. In this state, when the cable is pulled out, the reverse efficiency of the reduction gear device at the time of pulling out is added to the set value of the torque of the motor to which the reduction efficiency has been added, and this torque is applied as tension to the cable, resulting in a problem that when the cable is pulled out, the reduction efficiency is applied doubly as excess torque to the cable. In order to alleviate this problem, various measures have been taken, such as adopting expensive planetary reducers with good reversing efficiency or adopting bevel gears, but no fundamental solution has been found. Furthermore, these reducers are large in size, which also poses the problem that the dimensions of the drive unit of the cable reel must also become enormous. Furthermore, even though the cable reel is an electrical device, it requires periodic mechanical maintenance, such as changing the oil in the reducer, which can be a hassle. Furthermore, as the load rate of the reduction gear decreases, the reduction efficiency also decreases, so we were forced to adopt a small reduction gear with no margin of safety, sacrificing the margin of durability and coming up with a bare minimum design. Incidentally, in the cable reel described in Patent Document 3, attention is focused on the fact that the relationship between the winding angle and the load torque becomes slightly nonlinear due to the change in layers of the wound cable, and a proposal is made to control this slight torque change. However, the large deceleration efficiency that is applied twice as described above prevents the transmission of this slight torque change, and the rough torque change is not transmitted. The problem was that it could only transmit information.

[0005] The torque required to operate a cable reel varies depending on whether it is accelerating or decelerating, or whether it is winding or unwinding. However, because a cable reel is a device that simply follows the movement of the hoisting fixture suspended from a wire drum, it has no independence in determining its own movement and is therefore unable to control the torque required for the cable reel itself.

[0006] In view of these problems, the present invention has an object to provide a crane equipped with a vertical winding type cable reel for supplying power to a hoisting device suspended from the crane, which has improved cable reel dimensions, ease of maintenance, and improved torque control performance. [Means for solving the problem]

[0007] In order to solve the above problems, the crane equipped with a cable reel of the present invention is a crane equipped with a vertical winding type cable reel for supplying power to a hoisting tool suspended from a crane having a structure in which a reel drive motor generates torque in the winding direction to wind or unwind a cable onto a cable drum of the cable reel in conjunction with the up and down movement of the hoisting tool, A multi-pole motor is used as the reel drive motor, and a direct drive system is adopted in which the shaft of the cable drum of the cable reel is directly driven without a reduction gear. Based on the operation information of the control device that controls the up and down movement of the hoisting tool, This device is characterized by having a function of controlling the torque increase / decrease of the reel drive motor so as to increase the winding torque of the cable reel above the torque value when the cable reel is stopped only when the hoisting device is accelerating to wind up or when the hoisting device is decelerating to wind down.

[0008] In this case, based on the operation information of the control device that controls the up and down movement of the hoisting tool, The device can have a function of increasing or decreasing the torque of the reel drive motor so as to reduce the winding torque of the cable reel below the torque value when the hoisting device is decelerating during winding up and accelerating during winding down.

[0009] Further, based on the operation information of the control device that controls the up and down movement of the hoisting tool, It can have a function of controlling the torque of the reel drive motor to increase or decrease so that the winding torque of the cable reel becomes the same torque value as the torque value when the sling is being wound up at a constant speed.

[0010] Further, based on the operation information of the control device that controls the up and down movement of the hoisting tool, The device can have a function of controlling the torque increase / decrease of the reel drive motor so that the winding torque of the cable reel is reduced below the torque value when the hoisting device is being wound down at a constant speed. Effect of the Invention

[0011] According to the crane equipped with the cable reel of the present invention, a direct drive system using a multi-pole motor for the reel drive motor is adopted, which eliminates the need for a reduction gear, making it possible to reduce the dimensions of the drive unit and the protruding dimensions of the cable reel. By making the cable reel more compact, it is possible to effectively utilize the dimensions above the club of a small crane, and during regular maintenance of the cable reel, it is possible to eliminate the need for mechanical maintenance, such as changing the oil in the reduction gear, thereby improving the maintainability of the cable reel. In addition, by eliminating the reduction gear, it is now possible to transmit torque directly from the reel drive motor to the cable drum. This means that the reduction efficiency of the reduction gear is improved by It is possible to eliminate the factors that hinder torque control and improve torque control performance, which in turn eliminates the durability problem of the reducer, which has a low safety factor set in consideration of deceleration efficiency, and significantly improves the reliability of the cable reel device and the cable wound on the cable reel.

[0012] In order to demonstrate the performance that allows for fine torque control, the system determines how the cable reel will operate depending on the operating conditions of the wire drum that suspends the hoisting equipment, and increases the torque of the reel drive motor when the crane is accelerating while winding up and decelerating while lowering, and decreases the torque of the reel drive motor when the crane is decelerating while winding up and accelerating while lowering, and slightly decreases the torque of the reel drive motor when the crane is lowering, thereby reducing the burden on the cable and extending its lifespan. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic explanatory diagram of a crane to which the cable reel for power supply to a crane hoisting tool of the present invention is applied. [Diagram 2] FIG. 1 is an explanatory diagram of the structure of a cable reel that eliminates the efficiency of a reducer. [Diagram 3] 10 is an explanatory diagram of the effect of the reduction gear efficiency on the pull-out torque of the cable reel. FIG. [Figure 4] FIG. 4 is an explanatory diagram of the relationship between the load factor of the reducer and the efficiency of the reducer. [Diagram 5] FIG. 11 is an explanatory diagram of a case where the unwinding torque is suppressed by the boost torque during winding. [Figure 6] FIG. 11 is an explanatory diagram of a control method when deceleration efficiency is excluded. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a crane equipped with a cable reel of the present invention will be described with reference to the drawings.

[0015] FIG. 1 is a schematic explanatory diagram of a crane equipped with a cable reel of the present invention. The hoisting device GB, which is completely supported by a wire rope WR, is suspended from the wire drum WD on the club trolley TR of the crane CR, and the hoisting device GB is raised and lowered solely by the rotational force of the wire drum WD. A cable CA is hung down under constant tension from the cable reel RE located next to the wire drum WD, fixed with a fixing bracket FS, and powered by the hoisting device GB. The cable reel RE always generates a winding torque in the winding direction, and the cable CA is always under tension. When the hoisting gear GB is wound down, the cable wound around the cable reel RE is pulled out while maintaining a tension due to the winding torque of the cable reel RE, and when the hoisting gear GB is wound up, the cable CA is wound around the cable reel RE while maintaining a 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 only supports the cable CA and the fixing bracket FS and does not support the load of the hoisting fixture, but is set to a weak torque that only follows the up and down movement of the hoisting fixture GB.

[0016] FIG. 2 shows an embodiment of a crane equipped with a cable reel according to the present invention. The cable CA wound around the cable drum CD is connected to the slip ring SR through the hollow shaft SH from the cable drum CD, and the rotating cable CA is electrically connected to a fixed wiring connected to a carbon brush CB in contact with the slip ring SR. The reel drive motor DM connected to the hollow shaft SH generates a predetermined rotational torque controlled by the detection of the rotational position detector PG, and transmits this torque to the cable drum CD via the hollow shaft SH, generating a torque to wind up the cable CA. Conventionally, a general-purpose reel drive motor DM and brake BR with high rotation speed and small rated torque were used by placing a reducer between the reel drive motor DM and hollow shaft SH. Because of the high rotation speed, an induction motor can be used for the reel drive motor DM, which has the advantage of being able to be constructed with low-cost parts. However, when a planetary reducer is used, the reducer, reel drive motor, and brake are arranged in series from the hollow shaft SH, which creates a large protrusion dimension behind the cable reel, and when a bevel gear is used, the reducer, reel drive motor, and brake are arranged at a right angle upward or to the side from the hollow shaft SH, which creates a large protrusion dimension upward or to the side. In this embodiment, the reel drive motor DM is a multi-pole synchronous motor with a permanent magnet rotor that enables a rated output of large torque at low revolutions, and a large, high-torque brake is used for the brake, making it possible to directly drive the hollow shaft SH without using a reducer. This eliminates the factor that hinders torque control of the cable reel due to the reduction efficiency of the reducer, and also eliminates the protrusion of the drive unit that previously protruded significantly to the rear, above, or to the side of the cable reel, making it possible to effectively utilize the dimensions of the narrow club trolley TR where the cable reel RE is placed.

[0017] Although the cable reel RE is an electrical device that requires inspection by various electricians for regular maintenance such as replacement of the carbon brushes CB, wear management and grinding of the slip rings, damage check of the cable CA, management of the torque control constants, and replacement of the data storage battery, only the oil change in the reducer required maintenance by a mechanical engineer. In the RE cable reel, which does not have a reducer, maintainability has been improved by eliminating the only mechanical maintenance element, which was regular oil changes in the reducer, and leaving only electrical maintenance items.

[0018] The effect of the reducer efficiency on the payout torque of a cable reel is explained with reference to Figure 3. The winding torque HT required when winding cable CA is the sagging weight calculated by multiplying the weight per unit length of cable CA by the sagging length L plus the weight of the fixing bracket FS, and the cable load torque CT is the torque calculated by multiplying the dimension from the center position of cable drum CD to the sagging position of cable CA by the sagging weight. The winding torque HT required to wind cable CA is the torque value calculated by adding the acceleration torque AT for accelerating the inertial force of a rotating object such as cable drum CD or a linear moving object such as cable CA to the cable load torque CT. At this time, in order to generate the winding torque HT required to wind the cable CA, the reel drive motor DM must generate a motor torque MT that is equal to the torque of the reduction gear efficiency ηG added thereto. When the hoist GB is wound down and the cable CA is pulled while generating motor torque MT added with the torque of the above-mentioned reducer efficiency ηG, a torque equivalent to the reducer reverse efficiency ηR is further added and a pull-out torque RT is generated. At this time, the cable CA is subjected to both the reducer efficiency ηG and the reducer reverse efficiency ηR, and the pull-out torque RT at this time becomes approximately twice the required torque due to the double reducer efficiency, and the excessive tension caused by the large pull-out torque RT was a cause of damage to the cable CA. The torque due to this type of reducer efficiency accounts for a large proportion of the torque control of the electric motor, and even if fine torque control is attempted, it is buried in the reducer losses, so it is only possible to perform rough torque control with a coarse resolution.

[0019] As shown in Figure 4, when the load factor LG transmitted by the reducer becomes smaller, the efficiency of the reducer ηG deteriorates accordingly. Therefore, in cable reels where the efficiency of the reducer ηG is doubled and affects the cable, it is necessary to make the efficiency of the reducer high. It is not possible to use a sturdy reducer by increasing the safety factor of the reducer, and the reducer becomes a bottleneck and a sturdy cable is required. Furthermore, they were forced to adopt expensive reducers with good reversing efficiency, such as planetary reducers.

[0020] As a method for reducing, even as much as possible, the excessive pull-out torque RT caused by the torque due to the double reduction gear efficiency acting as a load in this way, Patent Document 1 discloses, as shown in FIG. 5, that the torque value is increased in response to a signal that the crane hoisting gear is being wound up, to set it as boost torque BT, and when not being wound up, that is, when the machine is stopped or being pulled out, the motor torque MT is obtained by subtracting acceleration torque AT equivalent to reduction gear efficiency ηG, so that the cable that has become slack due to load swaying while the machine is stopped is wound up slowly without accelerating, and when being pulled out, the pull-out torque RT is suppressed to an excessive torque due to only the reduction gear reverse efficiency ηR. However, the excess tension applied to the cable CA due to the reduction gear reverse rotation efficiency ηR could not be eliminated.

[0021] In order to prevent excessive tension being placed on the cable due to the load caused by the reduction gear efficiency, the cable reel of this crane uses a direct drive system that does not use a reduction gear, as shown in Figure 2. As a result, factors that impede torque transmission due to the efficiency of the reducer are eliminated, making it possible to perform fine torque control. However, since the cable reel RE follows the hoisting device GB, which moves up and down due to the wire drum WD, and is not a mechanism that operates independently, it is difficult for the cable reel RE to adjust the torque by itself. Accurate control is possible 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.

[0022] The torque required in each state of the cable reel RE will be described with reference to FIG. First, the cable load torque CT is calculated by multiplying the weight per unit length of the cable by the sagging length L, adding the weight of the fixing bracket FS to this to calculate the sagging weight, and then multiplying this sagging weight by the distance between the supports from the center of the cable drum CD to the cable sagging position. Therefore, the cable load torque CT is a value that changes depending on the sagging length L, and similar to the contents described in Patent Documents 1 and 3, it can be appropriately changed by changing the motor torque MT based on the detection 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 forces of rotating parts such as the cable drum CD and moving bodies such as the cable, to this cable load torque CT, and the torque due to the bearing efficiency ηB, which is a small but present loss in the bearings, is added to this torque value to obtain the winding acceleration torque MT1 required as the torque generated by the reel drive motor DM during winding acceleration. The value obtained by subtracting the acceleration torque AT from the winding acceleration torque MT1 is the steady-state winding torque MT2 required when the cable has finished accelerating and is being wound at a constant speed. The torque value obtained by subtracting the deceleration torque DT, which decelerates the inertial force of rotating parts such as the cable drum CD and moving bodies such as the cable CA, from the steady-state winding torque MT2 is the winding deceleration torque MT3 required when decelerating during winding. The torque MT4 required when the reel is stopped is the same as the torque MT2 required when the reel is stopped.

[0023] When operating in the unwinding PD direction, the acceleration torque AT, deceleration torque DT and bearing efficiency ηB all act in the opposite manner to when winding RU. Therefore, when accelerating while withdrawing, the torque value obtained by subtracting the acceleration torque AT and the bearing efficiency from the cable load torque CT is the torque during withdrawal acceleration MT5, and the speed is constant when withdrawing. When the cable is pulled out, the torque value obtained by subtracting the bearing efficiency ηB from the cable load torque CT is the steady-state pull-out torque MT6, and the addition of the deceleration torque DT to the steady-state pull-out torque MT6 is the pull-out deceleration torque MT7. In addition, by adding a small amount of a certain constant torque value in all states from MT1 to MT7 shown in Figure 6, it is possible to eliminate swaying of the cable due to disturbances such as load swinging and maintain a constant tension.

[0024] The state of the torque required by the cable reel RE as shown in FIG. 6 is determined based on control information from a winding speed control device (such as an inverter control device) that controls the winding motor that drives the wire drum WD. If the winding speed control device is accelerating winding, it is determined that the torque is MT1 during winding acceleration; if the winding speed control device is operating at a constant winding speed, it is determined that the torque is MT2 during steady winding; if the winding speed control device is decelerating winding, it is determined that the torque is MT3 during winding deceleration; if the winding speed control device is stopped, it is determined that the torque is MT4 during stoppage; if the winding speed control device is accelerating winding down, it is determined that the torque is MT5 during unwinding acceleration; if the winding speed control device is operating at a constant winding down speed, it is determined that the torque is MT6 during steady unwinding; and if the winding speed control device is decelerating winding down, it is determined that the torque is MT7 during unwinding deceleration.

[0025] In this case, when actually driving a direct drive cable reel that does not require a reducer, the reference torque setting value for the reel drive motor is set to the steady-state winding torque MT2 and stationary torque MT4, which are the cable load torque CT plus the torque associated with the bearing efficiency, plus a small amount of torque to eliminate cable sway due to the above-mentioned disturbances and to maintain a constant tension. When the winding speed control device is accelerating winding or decelerating winding down, it is possible to eliminate slack in the cable CA by outputting an instruction to increase the torque value to the cable reel RE. In addition, when the winding speed control device is decelerating winding or accelerating winding down, the load on the cable CA can be reduced by outputting an instruction to reduce the torque value to the cable reel RE. In addition, during the winding down operation, the winding speed control device can further reduce the strain on the cable by sending a torque reduction command to the cable reel RE by an amount equal to twice the torque value of the bearing efficiency.

[0026] The direct drive method, which does not use a reducer, removes the excessive load caused by the reducer efficiency ηG and the reducer reverse efficiency ηR that were generated in the reducer section, and the only factor impeding the transmission of torque is the small bearing efficiency ηB of the bearing section, which can be significantly reduced. Incidentally, if the cantilever structure in Figure 2, in which the cable drum CD is supported by the bearing BB on only one side, is changed to a double-support structure in which the bearings BB are placed on both sides of the cable drum CD, the bearing efficiency ηB value can be further improved, making more ideal torque control possible.

[0027] The above describes a crane equipped with a cable reel of the present invention based on an embodiment thereof, but the present invention is not limited to the configuration described in the embodiment, and the configuration can be appropriately changed without departing from the spirit of the present invention. [Industrial Applicability]

[0028] According to the crane equipped with the cable reel of the present invention, a direct drive system is adopted that does not require a reducer by using a multi-pole motor. This not only makes the crane more compact by eliminating the reducer, but also eliminates the drawback that the efficiency of the reducer is a doubly large factor in causing overload on the cable. This drawback is a bottleneck that makes it impossible to increase the safety factor of the reducer, which is a drawback of cable reels. It also eliminates the factor that hinders torque transmission between the motor and the cable. By eliminating the need for a reducer, fine torque control is possible, making this technology extremely valuable in 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 drive motor PG Rotational Position Detector BR Brake Bottom Bracket Bearing TB terminal block SR slip ring CB Carbon Brush HT Winding torque MT motor torque ηG Gear efficiency ηR Reducer reverse rotation efficiency RT Pull-out Torque LG reducer load factor BT Boost Torque AT acceleration torque CT cable load torque DT Deceleration Torque V speed t time RU Winding PD Drawer ηB Bearing efficiency MT1 Winding acceleration torque MT2 Winding torque at steady state MT3 Winding deceleration torque MT4 Stop Torque MT5 Pull-out acceleration torque MT6 steady-state torque MT7 Pull-out deceleration torque

Claims

1. A crane equipped with a vertical winding type cable reel for supplying power to a hoisting tool suspended from a crane having a structure in which a reel drive motor generates torque in the winding direction to wind or unwind the cable onto or from a cable drum of the cable reel in conjunction with the up and down movement of the hoisting tool, A multi-pole motor is used as the reel drive motor, and a direct drive system is adopted in which the shaft of the cable drum of the cable reel is directly driven without a reduction gear. Based on the operation information of the control device that controls the up and down movement of the hoisting tool, Only when the hoisting device is accelerating while winding up or when the hoisting device is decelerating while winding down, the device has a function of controlling the torque increase / decrease of the reel drive motor so that the winding torque of the cable reel is increased above the torque value when the cable reel is stopped. A crane equipped with a cable reel characterized by:

2. Based on operation information of a control device that controls the up and down movement of the hoisting tool, The reel drive motor has a function of increasing or decreasing the torque so that the winding torque of the cable reel is reduced below the torque value when the hoisting device is decelerating during winding up and accelerating during winding down. A crane equipped with a cable reel according to claim 1.

3. Based on operation information of a control device that controls the up and down movement of the hoisting tool, When the hoist is being wound up at a constant speed, the torque of the reel drive motor is increased or decreased to keep the winding torque of the cable reel the same as the torque value when the hoist is stopped. A crane equipped with a cable reel according to claim 1 or 2.

4. Based on operation information of a control device that controls the up and down movement of the hoisting tool, The reel drive motor has a function to increase or decrease the torque so that the winding torque of the cable reel is reduced below the torque value when the hoist is being wound down at a constant speed. A crane equipped with a cable reel according to claim 1, 2 or 3.

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