Direct drive crane

Abstract

To provide a direct drive driving crane in which a motor is directly attached to a wire drum of the crane without a speed reducer, the direct drive driving crane being compact, easy to produce, energy saving and excellent in maintenance.SOLUTION: There is provided a direct drive driving crane configured such that: load is supported by a crab frame CF via a shaft bearing BB with shafts on both sides of a wire drum WD of the crane; a rotating shaft of a motor DM is directly attached to the shafts of the wire drum WD without a speed reducer; an outer frame integrated with a stator of the motor DM is configured such that a base MB of a motor frame is placed on a base CB of the crab frame CF in the direction in which a wire rope WR wound around the wire drum WD is delivered, and that with force by which the load suspended by the wire rope WR pulls the wire drum WD in the direction in which the wire rope WR is delivered, the base MB of the motor frame is pressed against the base CB of the crab frame CF; and a catching device SP is provided for preventing the base MB of the motor frame from lifting off the crab frame CF from the base CB when the load is light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a crane that employs a so-called direct drive mechanism that drives a load directly from a motor without using a reducer. [Background technology]

[0002] In elevators and the like, direct drive technology has already been widely adopted to produce space-saving elevators that do not require a machine room and high-speed elevators that offer a comfortable ride (see, for example, Patent Document 1), and as a result, large-capacity direct drive motors have also been manufactured. This large-capacity direct drive motor can be converted into the large-capacity motor required for cranes, and given this technical background, there has been a demand for a simple and compact direct drive crane that does not require a reducer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-107048 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a direct drive motor is directly connected to the wire drum of a crane's hoisting device and the wire drum is supported by this motor, any impact on the wire drum due to improper lifting operations during crane operation will be directly applied to the motor frame, resulting in the problem of damage such as cracks in the motor frame.

[0005] Furthermore, when a load is applied to the crane's wire drum, the wire drum bends, causing misalignment between the motor shaft and the wire drum shaft. If a coupling were used to absorb this misalignment, it would have to protrude significantly outward from the wire drum, making it difficult to use a coupling due to its dimensions.

[0006] In view of the problems that arise when a direct drive motor is applied to the wire drum of the hoisting device of the crane, an object of the present invention is to provide a direct drive crane in which a motor is attached directly to the wire drum of the crane without a reducer, which is compact, easy to manufacture, energy-efficient, and easy to maintain. [Means for solving the problem]

[0007] In order to achieve the above object, the direct drive crane of the present invention supports the load on the club frame via bearings on both sides of the shaft of the crane's wire drum, and the rotating shaft of the motor is attached directly to the shaft of the wire drum without using a reducer. Be The outer frame integral with the stator of the motor is Mo The base of the motor frame is placed on the base of the club frame in the direction in which the wire rope wound around the wire drum is unwound, and the load suspended by the wire rope pulls the wire drum in the wire rope's unwinding direction, causing the base of the motor frame to be pressed against the base of the club frame, thereby flexibly fixing the motor to the club frame. This prevents the motor from rotating in the direction in which the load is pulled, and enables the torque generated by the motor to support the load and move it up and down. In addition, when the load is light, the inertial force generated during acceleration and deceleration tends to cause the base of the motor frame to lift up from the base of the club frame, and this is prevented by providing a structure that prevents the base from lifting up by providing a catch device. This prevents the impact on the wire drum caused by improper ground clearance operations during crane operation from being directly applied to the motor frame, and at the same time, the deflection dimension of the wire drum is such that the contact position between the base of the motor frame and the base of the crab frame is offset, eliminating core runout, allowing for a compact arrangement without the need for a coupling, and eliminating the need for shaft centering work, resulting in a low-cost, easy-to-manufacture crane.

[0008] In this case, since the motor is a special dedicated motor, one or more motors can be fitted skewer-like onto the shaft of the wire drum, and the output can be adjusted by changing the number of motors fitted. This makes it possible to limit the number of motor types and ensure the number of motors produced, thereby reducing costs through the mass production effect of motors. Furthermore, it makes it easier to produce and stock motors and control devices, ensuring stable crane production, and once the crane is in operation, it becomes possible to provide a rapid supply of parts using stocked motors and control devices.

[0009] In addition, for the horizontal movement parts of the crane, such as traversing and traveling, the motor's rotating shaft is attached directly to the axis of the wheel for horizontal movement without going through a reducer, and the outer frame integrated with the motor's stator can be equipped with a horizontal movement device that flexibly fixes movement in the forward and reverse directions to the crane frame with anti-rotation arms. This allows the motor to directly drive the wheels for horizontal movement without using a reducer or coupling, resulting in a crane with a compact structure that is easy to manufacture at low cost and requires few assembly steps.

[0010] In addition, for cranes whose horizontal movement speeds, such as traversing or traveling, are slow, a horizontal movement device can be provided in which a gear is fixed to the wheel for horizontal movement and this gear meshes with a small gear attached to the rotating shaft of the motor. This makes it possible to realize a crane with a slow horizontally moving part that has a compact structure, requires few assembly steps, and is easy to manufacture at low cost. [Effects of the Invention]

[0011] The direct drive crane of the present invention solves the problem of misalignment between the wire drum shaft and the motor shaft caused by bending of the wire drum when a load is applied to the crane's wire drum, and makes it possible to connect the wire drum and motor directly without using a coupling, thereby realizing a compact and easy-to-manufacture crane. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a structural explanatory diagram of a hoisting device for a direct drive crane according to the present invention; [Figure 2] FIG. 2 is a structural explanatory diagram of the drive device for the horizontal operating portion of the direct drive crane of the present invention. [Figure 3] 1 is a structural explanatory diagram of the drive device of the horizontal movement portion of the direct drive crane of the present invention when the horizontal movement is at a low speed. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a direct drive crane according to an embodiment of the present invention will be described based on examples with reference to the drawings.

[0014] FIG. 1 shows an explanatory diagram of the structure of a hoisting device for a direct drive crane according to the present invention. When the force of the load W suspended by the wire rope WR is applied to the wire drum WD of the crane, the center of the wire drum WD bends slightly downward and both sides bend slightly upward. At this time, the deformation of the crab frame CF differs from the fulcrum position of the wire drum WD, so the crab frame The deformation of the CF and the wire drum WD is not synchronized, causing misalignment at the connection points of the shafts between the rotating devices arranged on the club frame CF. The misalignment of the shaft connections between the rotating equipment arranged on the club frame CF can also occur because the crane girder CG, which is the contact surface of the wheels WH at the four corners of the club frame CF, is not completely flat, and as the club moves horizontally, slight changes in shape of the crane girder CG cause the club frame CF to deform slightly. It can also occur when a crane moves horizontally over a building's runway girder that is not perfectly flat. In order to absorb the misalignment of the transmission shaft that causes deformation due to the bending of the wire drum, conventional methods have included using a coupling between the reducer and the wire drum WD, absorbing the misalignment by misaligning the tooth contact area between the gear attached to the wire drum WD and the pinion that is combined with it, or forcibly restraining the deformation due to the bending of the wire drum by using the strength of the reducer box.

[0015] Incidentally, elevators that have already put into practical use a system in which the wire drum WD and the motor DM are directly connected employ a structure in which deformation of the wire drum WD is absorbed by the gap between the rotor and stator of the motor. However, since the wire drum WD of the crane takes up a long amount of wire rope WR, the length of the wire drum WD is also long, and the amount of deflection of the wire drum WD also increases accordingly. For this reason, if a crane were to use the same method as an elevator, where the gap between the motor's rotor and stator is used to absorb the load, an imbalance in the gap could cause disturbances, leading to an overcurrent trip, and in extreme cases, the motor's rotor and stator could come into contact with each other. For this reason, a method for connecting the wire drum WD and the motor DM that is suitable for the crane is required.

[0016] Furthermore, there is a problem specific to cranes. If the motor DM is attached directly to the crane's wire drum WD and the motor DM supports the wire drum, excessive force will be applied to the motor DM when performing impact loads during rough lifting operations or when accidentally lifting a fixed object on the ground, resulting in damage to the motor DM. For this reason, a structure was required that would prevent impact loads from the load side from being directly applied to the motor DM.

[0017] To solve these problems specific to cranes, the structure of the hoisting device for the direct drive crane of the present invention shown in Figure 1 supports the wire drum WD on both sides by the crab frame CF via bearings BB, so that even if an impact load is generated when rough lifting operations are performed or when earth lifting is performed accidentally to lift a fixed object on the ground, the force is not directly applied to the expensive motor DM. The hollow boss on the rotor side of the motor DM is fitted onto the shaft of the wire drum WD and fixed in the direction of rotation with a key or spline, and the motor frame on the stator side of the motor DM is installed without being fixed, with the surface of the motor frame's base MB abutting the surface of the club frame CF's base CB, i.e., the motor support base CB provided on the club frame CF side. At this time, the surfaces of the motor frame's base MB and the motor support base CB provided on the club frame CF side are in contact in a direction that suppresses the rotational force generated when the load W pulls the wire rope WR. The force of the load W pulling the wire rope WR presses the motor frame's base MB against the motor support base CB provided on the club frame CF side, fixing the motor DM in place. However, because it is simply placed there without being fixed with bolts or the like, the wire drum WD bends due to the force of the load W, causing the wire drum shaft to warp, and the motor DM also moves in conjunction with this, preventing axial misalignment. At this time, the contact surface between the motor frame base MB and the motor support base CB on the club frame CF side is slightly This slight misalignment eliminates the positional misalignment of the motor DM, which is linked to the deformation of the wire drum WD. By adopting this structure, excessive force is not mechanically applied to the motor DM, preventing damage to the motor. Furthermore, in this structure, even if excessive force is applied from the load, it is limited to the torque limiter value of the motor DM, and slippage occurs between the stator and rotor of the motor DM, electrically controlling the motor to prevent excessive force from being applied to each part.

[0018] The load on the crane's hoisting device, i.e., the load on the crane's wire drum WD, is characterized by the fact that the load on the wire rope WR exerts a pulling force WF in only one direction.As shown in Figure 1, even if the motor DM is not fixed to the club frame CF with bolts or the like, the base MB of the motor frame is pressed in one direction against the motor support base CB provided on the club frame CF side and fixed in place. However, when the load W is light and the inertial force of the wire drum WD and the rotor of the motor DM is greater than the pulling force WF of the load W when decelerating the rotation in the winding direction and accelerating the rotation in the unwinding direction, this greater force acts to lift the motor frame base MB from the motor support base CB of the club. To suppress this lifting force, a lifting prevention SP is provided, and this lifting prevention SP is installed with a slight play dimension to allow for wobble due to bending of the wire drum WD, etc. This backlash dimension is adjusted to the minimum dimension that allows for misalignment of the shaft center due to bending of the wire drum WD, etc., and by filling the gap with cushioning material such as leather or rubber, it allows for slight movement of the motor while eliminating impact when lifting force is generated.

[0019] Crane hoisting devices require motors DM with various capacities because the loads they can lift and the hoisting speeds vary. However, motors DM that can directly drive wire drum WD are specialized dedicated motors, which can be expensive if the production volume is small. Therefore, as shown in Figure 1, by using a structure in which multiple motors DM (three in this embodiment) are attached in a skewer-like manner to the shaft of the wire drum WD, the number of different motor capacities can be reduced, the number of identical motors produced can be increased, and costs can be reduced through mass production effects.Furthermore, this makes it easier to produce and stock motors and control devices, ensuring stable crane production, and once the crane is in operation, it becomes possible to provide a rapid supply of parts using stock motors and control devices. Furthermore, by connecting the motors to one shaft with a key or the like, it is possible to precisely align the magnetic pole positions of the rotors of each connected motor to the same position, even if the motors used are synchronous motors.The motor support base CB, which is located on the club frame CF side that holds the stator, can be precisely machined to the same height through integral machining, and the anti-lift devices have the same gap dimensions, so the relative positions of the rotor and stator of each motor can be made the same. This allows the synchronous motors arranged in parallel to be smoothly driven in parallel. Furthermore, if the shafts of the motor DM and wire drum WD are connected with a spline, care must be taken to mark the spline teeth so that they do not become misaligned during assembly.

[0020] Fig. 2 shows an explanatory diagram of the structure in which the wheels WH are directly driven by the motor DM for horizontal movement of the crane, such as traversing and traveling, without using a reducer. The hollow boss on the rotor side of the motor DM is fitted onto the shaft of the wheel WH, which is supported on both sides by bearings BB, and is fixed in the direction of rotation by a key or spline, etc. The frame of the motor DM, which is the stator side of the motor DM, is used to fix the stator against the rotational force in the forward or reverse direction that is generated in the stator by the reaction force caused by the rotor of the motor DM generating a driving force. The stator of the motor DM is fixed to the crane frame GF by the retaining arm AR, with some play left. This backlash corresponds to slight deformation of the crane frame GF due to the horizontal movement of the crane.The speed control device for the motor DM starts the crane at a low speed and accelerates linearly when accelerating, and when decelerating it linearly decelerates to a low speed before stopping, so there is no rattle or shock caused by this backlash when starting and stopping. By adopting the structure shown in Figure 2, it is possible to create a compact structure that does not require coupling between the wheel axle and motor shaft, and it is possible to create an inexpensive structure that is easy to manufacture because there is no need to align the wheel axle and motor shaft during assembly.

[0021] As a method for driving the wheels WH of the horizontally moving parts of a crane, such as for traversing or traveling, if the speed of the horizontally moving parts is slow, it is possible to drive them by meshing the wheel gear GR fixed integrally with the wheels WH with the pinion gear PN built into the output shaft of the motor DM, as shown in Figure 3. In this case, slight deformations of the crane frame GF are absorbed by a slight misalignment in the meshing state between the wheel gear GR and the pinion gear PN. At this time, by performing crowning processing to give the tooth flank shapes of the wheel gear GR and pinion PN a slight curve in the face width direction, the meshing misalignment between the wheel gear GR and pinion PN is smoothed.

[0022] During the assembly process of a crane, a lot of time is spent on centering the joints of the rotating shafts. The direct drive crane structure of the present invention is a structure that can eliminate the burden of centering work and realizes a structure that is easy to assemble. In addition, by eliminating the reducer, noise and vibrations generated at the meshing points of the reducer are eliminated, making the structure easier to use for high-speed operation. In addition, mechanical loss of approximately 10 to 15% occurs in the reducer section, and this loss in the reducer accounts for the majority of mechanical loss, making it effective in saving energy. Furthermore, the crane's hoisting reducer contains a large amount of lubricating oil, and the burden of oil changes that had to be carried out periodically can be eliminated by eliminating the reducer. Furthermore, the hoisting reducer of a crane is the most important mechanical component of the crane, but by eliminating the reducer, it is possible to achieve a highly reliable crane with a low risk of mechanical breakdown.

[0023] Furthermore, direct drive motors are specialized, dedicated motors that are difficult to obtain in an emergency. However, by limiting the types of motor capacity and adopting a system in which motor capacity is adjusted according to the number of motors, it becomes possible to easily produce motors and control devices in lots and to stockpile them for crane production, enabling stable crane production. Furthermore, once the crane is in operation, it becomes possible to create a system in which service parts can be supplied from stock parts immediately in response to requests from customers who use the crane.

[0024] The direct drive crane of the present invention has been described above based on its embodiments, but the present invention is not limited to the configurations described in the above embodiments, and the configuration can be changed as appropriate within the scope of the invention. [Industrial Applicability]

[0025] The direct drive crane of the present invention is compact, easy to assemble, energy-efficient, does not require periodic disposal of waste reducer oil, has a low risk of mechanical failure, eliminates vibration and noise caused by gear meshing, and can easily accommodate higher speeds. It is possible to realize a crane with performance that could not be achieved with cranes of conventional structures, and can be effectively used industrially. [Explanation of symbols]

[0026] WD Wire Drum DM Direct Drive Motor WR Wire Rope W load CF Club Frame WH Wheels Bottom bracket bearing BR Brake MB motor frame base CB club frame base CG crane girder SP Floating prevention LS Limit Switch WF Pulling force of the suspended load AR anti-rotation arm GF Crane Frame GR Wheel Gear PN Pinion

Claims

1. A direct drive crane is characterized in that the load is supported on the crab frame by bearings on both sides of the crane's wire drum, the motor's rotating shaft is attached directly to the wire drum shaft without a reducer, and the outer frame, which is integral with the motor's stator, has a motor frame base placed on the crab frame base in the direction in which the wire rope wound around the wire drum is paid out.The load suspended by the wire rope pulls the wire drum in the wire rope's payout direction, forcing the motor frame base against the crab frame base, thereby flexibly fixing the motor to the crab frame.When the load is light, the inertial force generated during acceleration and deceleration will cause the motor frame base to tend to lift up from the crab frame base, but this is prevented by the provision of a catch device.

2. 2. A direct drive crane according to claim 1, wherein one or more motors are fitted in a skewer-like manner onto the shaft of the wire drum, and output is adjusted by changing the number of motors fitted.

3. 3. A direct drive crane according to claim 1 or 2, characterized in that the rotating shaft of the motor is attached directly to the axle of the wheels for horizontal movement without a reducer, and the outer frame integral with the stator of the motor is provided with a horizontal movement device that flexibly fixes movement in the forward and reverse directions to the frame of the crane with anti-rotation arms.

4. 3. A direct drive crane according to claim 1 or 2, further comprising a horizontal movement device having a structure in which a gear is fixed to a wheel for horizontal movement and the gear meshes with a small gear attached to the rotating shaft of the motor.

Images