Electric hoisting device

Abstract

To provide a compact, lightweight electric hoisting device that is durable and can be mounted on a drone.SOLUTION: There is provided an electric hoisting device in which the power of a motor is transmitted to a drum in the order of a reduction gear mechanism and a braking mechanism, and the suspended load wound around the drum can be lifted and lowered by switching the rotation direction of the motor between forward and reverse. The braking mechanism comprises a clutch consisting of a screw shaft connected to the motor so as to be rotatable forward and backward, a clutch in which a clutch plate and a friction plate are alternately arranged on the screw shaft through a lining, and a nut pressing portion which is screwed between the drum of the screw shaft and the clutch and presses the clutch so that the clutch can be connected by the thrust at the time of tightening to the clutch side. The screw shaft has a male screw portion in which the nut pressing portion is screwed to a support shaft inserted through the rotation center of the drum. The nut pressing portion is provided so as to be integrally rotatable with respect to the drum. The load torque on the drum side tightens the nut pressing portion while the motor is stopped, so that the clutch exerts a braking force capable of holding the load at a constant height.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] This invention relates to an electric hoisting device that raises and lowers a load by switching the rotation direction of a motor between forward and reverse, and is equipped with a mechanical brake that converts the load torque acting on a drum by the load and the lifting torque of the motor into thrust for operating a clutch using a feed screw mechanism. [Background technology]

[0002] Patent Document 1 discloses a mechanical brake in which a brake mechanism 4 is provided between the motor 1 and a drum 2 in a hoist that raises and lowers a load by switching the rotation direction of the motor 1 between forward and reverse, and which is capable of generating and releasing a braking force depending on the difference in rotational speed between a driven gear 32 that meshes with a drive gear 31 of the motor 1 and an output shaft 21 (the support shaft of the brake mechanism) to the drum 2 (symbols are taken from Patent Document 1; the same applies below up to the section "Problem to be solved by the invention").

[0003] According to this winch, the driven gear 32 and the output shaft 21 on the drum 2 side constitute a feed screw mechanism (screw mechanism 41). When the motor 1 is operated in the winding direction, the output shaft 21 rotates in a fixed direction via the drive gear 31, and the driven gear 32 obtains a thrust to press the friction plates 44 and 45 by the screw drive, generating a braking force, and the load is hoisted by the winding torque of the drive system such as the motor. On the other hand, when the motor 1 is operated in the lowering direction, the driven gear 32 moves in a direction away from the friction plates 44 and 45, releasing the braking force, and the drum 2 rotates in the payout direction to lower the load. During this lowering operation, if the rotation speed of the output shaft 21, i.e., the rotation speed of the drum 2 in the payout direction, exceeds the rotation speed of the driven gear 32, i.e., the rotation speed in the lowering direction on the motor 1 side, the driven gear 32 moves again in a direction pressing the friction plates 44 and 45 to generate a braking force, and the load is lowered at the winding speed of the motor. Incidentally, while the motor 1 is stopped, a rotational torque in the lowering direction is applied to the drum 2 by the weight of the suspended load, which rotates the output shaft 21, causing the driven gear 32 to move in the pressing direction of the friction plates 44, 45, just as during the hoisting operation, thereby exerting a braking force and holding the suspended load at a constant height. In this way, the mechanical brake of Patent Document 1 mechanically adjusts the braking force by causing the driven gear 32 facing the friction plates 44, 45 to reciprocate in the axial direction by the feed screw mechanism with the output shaft 21. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-5972 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in Patent Document 1, the driven gear 32 is provided with two threads, one inside and one outside, which are a female thread for forming a feed screw mechanism (screw mechanism 41) with the output shaft 21, and a male thread for forming a power transmission mechanism (power transmission gear 3) between the drive gear 31 and the motor. This allows the driven gear 32 to simultaneously perform a rotational motion for power transmission and an axial motion (linear motion) for adjusting the braking force. Therefore, when the driven gear 32 moves in the axial direction, in addition to a normal frictional force, an axial frictional force is also generated at the meshing portion with the drive gear 31. Therefore, in the hoist of Patent Document 1, the meshing portion between the driven gear 32 and the drive gear 31 wears out faster than usual, which affects the durability of the device.

[0006] In addition, in the device of Patent Document 1, the rotating shaft of the drum 2 is composed of a member separate from the output shaft 21, and they are journaled in parallel to each other. For this reason, a power transmission gear 5 for connecting the output shaft 21 and the drum 2 is also required on the drum 2 side, and when the power transmission gear 3 on the motor 1 side is included, the device inevitably becomes larger. In this regard, drone-based parcel delivery services have been realized in recent years, and as a prerequisite for this, it is important to keep the size and weight of the winch so that it can be mounted on a drone.

[0007] The present invention has been made to solve the above-mentioned problems, and its object is to provide a small, lightweight electric hoisting device that is highly durable and can be mounted on a drone. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides an electric hoisting device that transmits the power of a motor to a drum through a reduction gear mechanism and then a braking mechanism, and that can raise and lower a load wound around the drum by switching the rotation direction of the motor between forward and reverse. The braking mechanism comprises a screw shaft that is connected to the motor via the reduction gear mechanism so as to be rotatable forward and reverse, a clutch formed by alternately arranging clutch plates and friction plates on the screw shaft via a lining, and a brake mechanism that is screwed between the drum and the clutch of the screw shaft so as to be tightened toward the clutch side, The clutch is provided with a pressing nut portion that can frictionally join the clutch plate and the friction plate with the lining by the thrust force generated when tightening, and the screw shaft is formed with a male thread portion into which the pressing nut portion screws onto a support shaft inserted into the rotation center of the drum, and the pressing nut portion is provided so as to be rotatable integrally with the drum. When the motor is stopped, the pressing nut portion rotates in the tightening direction due to the load torque on the drum side caused by the suspended load, and the clutch exerts a braking force capable of holding the suspended load at a constant height.

[0009] According to this means, the rotational motion of the motor and the drum is converted into a linear reciprocating motion in which the pressing nut part screws the screw shaft left and right to engage and disengage with the clutch by a feed screw mechanism using the drum's support shaft as a screw shaft. During such reciprocating motion of the pressing nut part, the presence or absence of a thrust force pressing the clutch determines the presence or absence of a braking force by the clutch. That is, when the motor is rotated in the hoisting direction, the pressing nut part is tightened by the screw shaft that rotates in conjunction with the motor, and the clutch acts to transmit the drive system torque of the motor and reduction gear mechanism to the drum, but when the motor is stopped, the pressing nut part is tightened in conjunction with the rotation of the drum in the payout direction due to the load torque of the suspended load, and exerts a braking force that holds the suspended load at a constant height, functioning as a so-called brake clutch. On the other hand, when the motor is rotated in the payout direction of the load, the screw shaft rotates in the opposite direction to that during hoisting, displacing the pressing nut in the direction opposite to the tightening direction of the clutch, releasing the braking force, and the drum becomes free to rotate, causing the load to descend due to its own weight. Furthermore, if the rotation speed of the drum during the descent, i.e., the rotation speed of the pressing nut in the descending direction, exceeds the rotation speed of the motor in the payout direction, i.e., the rotation speed of the screw shaft in the payout direction, the rotation of the pressing nut in the descending direction becomes dominant, and the pressing nut is tightened again, and the braking force is restored by the thrust. As a result, the load can be lowered by the rotation torque in the payout direction of the motor, and thereafter, the brake force is repeatedly released and restored depending on the rotation difference between the pressing nut and the screw shaft, allowing the load to descend until the motor is stopped.

[0010] During these basic operations, in the present invention, the pressing nut portion is not in meshing relationship with the drive system, such as the motor and reduction gear mechanism, so that no undue force (friction) acts on the meshing portions of the drive system when the braking force is applied or released.

[0011] Furthermore, in the present invention, the screw shaft is formed by the drum support shaft, and the braking mechanism is concentrated on this support shaft, which makes it possible to reduce the number of parts and to make the device smaller and lighter, which is rational.

[0012] As a specific means to be added to the above means, it is preferable that the clutch is composed of a multi-plate clutch consisting of multiple sets of clutch plates, linings, and friction plates, and the number of sets can be changed to obtain a braking force according to the weight of the suspended load. If the drive system consisting of the motor and the reduction gear mechanism has the same configuration (output torque), the thrust of the pressing nut part when tightened to the clutch side is constant, so that a braking force corresponding to the weight of the suspended load can be obtained by simply changing the number of sets of the multi-plate clutch. This is particularly effective when holding the suspended load at a constant height while the motor is stopped. For example, if three sets of multi-plate clutches can obtain a braking force to hold a suspended load of 30 kg, five sets of multi-plate clutches can hold a suspended load of 50 kg.

[0013] In addition, in a method in which a clutch receiving portion is provided on the screw shaft facing the pressing nut portion and this receiving portion constantly regulates reverse rotation by a ratchet, even if the pressing nut portion is tightened by reverse rotation, the ratchet works and the receiving portion does not rotate in the same direction, and receives the thrust of the pressing nut portion in a state of stopped rotation. Therefore, when the motor is stopped, the thrust of the pressing nut portion toward the clutch side is received by the receiving portion, so that the clutch is completely in a frictional connection state and a braking force capable of holding the load at a constant height can be reliably obtained. Also, even when the motor is operating in the hoisting direction, the rotation of the drum in the downward direction is regulated by the regulation of reverse rotation of the receiving portion, preventing the load from falling.

[0014] Furthermore, by setting the static friction torque of the drive system, which is the rotational resistance of the motor and the reduction gear mechanism, to be balanced with the load torque on the drum side when the motor is stopped, even if the motor does not have a brake such as an electromagnetic brake, the load is not released from the drum while the motor is stopped, and a braking force capable of holding the load at a constant height can be maintained. Also, if a load that exceeds the braking force acts on the drum while the motor is stopped, the static friction torque is exceeded and the drive system is allowed to rotate in reverse. Therefore, it is possible to mitigate impacts on the hoisting device caused by the excess load. This is effective, for example, when the device is mounted on a drone to construct a load delivery system, and is useful for mitigating impacts on the drone even if the load gets caught on a tree during delivery.

[0015] On the other hand, when the load torque on the drum side falls below a certain level during the descent of the load by the reverse drive of the motor, the pressing nut receives a reaction from the clutch against the tightening, loosening the tightening, and disengaging the clutch. If the load torque falls below a certain level due to the load landing, for example, the pressing nut loosens and the clutch is disengaged. Once loosened, the pressing nut rotates together with the screw shaft, and the clutch remains disengaged even if the motor continues to rotate in reverse. Therefore, in the present invention, even if the motor is stopped late after the load lands, the clutch is disengaged at the same time as the load lands, so the rope is not reeled out from the drum, and the backlash phenomenon can be prevented.

[0016] Furthermore, although the reduction gear mechanism can be composed of only spur gears, it is preferable to compose at least a part of it with planetary gears, since this allows the reduction gear mechanism to be made smaller and lighter while still obtaining the necessary torque.

[0017] The electric hoist of the present invention can be used in all loading and unloading fields, not just general loading and unloading in factories, warehouses, construction sites, etc. Furthermore, if this device is mounted on a drone, it will be possible to easily deliver cargo to remote areas where land routes are not developed, and the possibilities are endless. Effect of the Invention

[0018] According to the present invention, the pressing nut portion, which obtains and releases the braking force by the thrust, is not directly connected to the reduction gear mechanism, so that the various gears that make up the reduction gear mechanism do not wear more than usual and have high durability. Moreover, since the screw shaft is formed by the drum support shaft and the braking mechanism is integrated onto this support shaft, a small and lightweight electric hoist can be provided. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is an overall perspective view of an electric winding device according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a perspective view of the main part excluding the frame. [Diagram 3] Overall cross-sectional view of the same [Figure 4] Enlarged cross-sectional view of the main part of the same [Diagram 5] FIG. 1 is an exploded perspective view of the main part from the left side of the first embodiment. [Figure 6] FIG. 1 is an exploded perspective view of the main part from the right side. [Figure 7] FIG. 2 is an explanatory diagram showing the ratchet mechanism of the pressing nut portion of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is an overall perspective view of an electric hoisting device according to one embodiment of the present invention, in which 1 is a motor and 2 is a drum. A rope 3 is wound around the drum 2 (wound left when viewed from the right side of the drawing), and a load W is fixed to its end. 4 is a level wander, which reciprocates left and right on a traverse cam 5 that rotates in conjunction with the drum 2, thereby winding the rope 3 evenly around the drum 2. A controller (not shown) connected to terminals 6 is used to operate and stop the motor 1 and switch the rotation direction between forward and reverse, thereby rotating the drum 2 forward and reverse to raise and lower the load W or hold the load W at a constant height.

[0021] In this device, the motor 1, drum 2, reduction gear mechanism and braking mechanism are installed between four parallel plate-like frames F1-4. As shown in Figures 2 and 3, the reduction gear mechanism is made up of, from the motor 1 side, two sets of planetary gears 7 and 8, two transmission gears 9 and 10 made of spur gears, and an output gear 11 made of a spur gear with a larger diameter than the transmission gears 9 and 10. Of these, the final output gear 11 is fixed integrally to one end (the right end in the drawing) of a support shaft 12 inserted through the center of rotation of the drum 2. For ease of explanation, the teeth of the gears 7 to 11 are not shown.

[0022] The torque of the motor 1 is increased by this reduction gear mechanism and then transmitted to the drum 2 via the braking mechanism. The braking mechanism in this embodiment is composed of a feed screw mechanism with the support shaft 12 of the drum 2 as the screw shaft, and a multi-plate clutch.

[0023] Of these, the feed screw mechanism, as shown in Fig. 4, is formed by forming a male screw portion 12a on one side of the support shaft 12 to form a screw shaft, and a pressing nut portion 13 is screwed into the male screw portion 12a. Therefore, when the support shaft 12 rotates, the pressing nut portion 13 reciprocates left and right on the support shaft 12 in a direction following the rotation direction of the support shaft 12 by screw driving. Also, even when the support shaft 12 is stopped rotating (synonymous with when the motor 1 is stopped), the pressing nut portion 13 rotates in conjunction with the rotation of the drum 2 in the payout direction due to the load of the suspended load W, and screw-drives the support shaft 12.

[0024] As shown in Fig. 4, the multi-plate clutch, which constitutes one component of the braking mechanism, is composed of multiple sets of clutch plates 14 and friction plates 16 arranged alternately on the support shaft 12 with linings 15 interposed therebetween. As shown in Figs. 5 and 6, the clutch plates 14 have projections 14a provided at two locations on their outer periphery that fit into notches 17a formed in the housing cylinder of the receiving portion 17. Meanwhile, the friction plates 16 have a square shaft shape whose central hole 16a matches the shaft base 13a of the pressing nut portion 13, so that they can rotate together with the pressing nut portion 13. In this embodiment, the multi-plate clutch has five linings 15, but the initial braking force can be increased by increasing the number of sets.

[0025] The multi-plate clutch is accommodated in (the accommodating cylinder portion of) receiving portion 17 which faces pressing nut portion 13 on support shaft 12. As shown in Figs. 5 and 6, receiving portion 17 constitutes a first ratchet 18 which is a ratchet wheel, and a claw 18a meshes with teeth 17b formed on receiving portion 17 to constantly restrict reverse rotation of receiving portion 17. Therefore, even if pressing nut portion 13 rotates in the payout direction of load W, receiving portion 17 will not reverse. Incidentally, claw 18a is rotatably supported by pin 18b which is journalled between frames F1 and F2 as shown in Fig. 1.

[0026] On the other hand, the pressing nut portion 13 in the feed screw mechanism constitutes a second ratchet 19 using the same as a ratchet wheel, as shown in Figs. 5 and 6. The pawl 19a of the second ratchet 19 is rotatably supported in the end face recess 2a of the drum 2, and is constantly biased by a leaf spring 19b so as to mesh with the teeth 13b formed on the pressing nut portion 13. As shown in Fig. 7, the pawl 19a of this second ratchet 19 meshes with the teeth 13b when the pressing nut portion 13 rotates in the hoisting direction of the load W (forward rotation R1) due to the forward drive of the motor 1, and when viewed from the drum 2 side, the pawl 19a meshes with the teeth 13b when the drum 2 tries to rotate in the payout direction (reverse rotation R2) due to the load torque of the load W. For this reason, as long as the load W is wound around the drum 2, the claws 19a mesh with the teeth 13b due to the load torque, and the drum 2 and the pressing nut portion 13 rotate together in the forward and reverse directions. In this embodiment, since the drum 2 is elastically biased toward the pressing nut portion 13 (coil spring 20 in FIG. 3), the drum 2 follows the pressing nut portion 13 even while it reciprocates on the support shaft 12, so that the meshing of the second ratchet 19 does not come off.

[0027] Next, the operation of this electric hoisting device will be described with reference to Fig. 4. To clarify the directions, in this embodiment, the rope 3 is wound counterclockwise around the drum 2, and based on this, in the following description of the operation, the rotational direction (counterclockwise) in which the rope 3 is wound up to raise the load W is defined as forward rotation R1, and the rotational direction (clockwise) in which the rope 3 is paid out to lower the load W is defined as reverse rotation R2. Also, the spindle 12 and the pressing nut portion 13 in the feed screw mechanism are screwed together with a left-handed screw (reverse screw), and the tightening direction (rightward in the drawing) in which the pressing nut portion 13 is displaced on the spindle 12 toward the clutch by the screw propulsion due to the relative forward rotation R1 is defined as forward direction S1, and the loosening direction in which the pressing nut portion 13 is separated from the clutch is defined as reverse direction S2.

[0028] Now, if a load W is fixed (suspended) on the rope 3 while the motor 1 is stopped, the weight of the load W will cause the drum 2 to rotate in the reverse direction R2. When the drum 2 rotates in the reverse direction R2, the reverse torque (load torque) is transmitted to the pressing nut portion 13 via the second ratchet 19, and the pressing nut portion 13 rotates in the reverse direction R2. When the pressing nut portion 13 rotates in the reverse direction R2, the pressing nut portion 13 displaces the support shaft 12, which is in a stopped state of rotation, in the forward direction S1 by the left-handed screw action, and is tightened so as to press the clutch. At this time, the pressing nut portion 13 presses the clutch with a thrust force corresponding to the reverse torque R2 of the drum 2. Due to the thrust of the pressing nut portion 13, the clutch plate 14 and the friction plate 16 in the clutch are frictionally joined by the lining 15, and a braking force is obtained. During this time, the reverse rotation R2 torque of the pressing nut portion 13 (and thus the load torque on the drum 2 side) is also transmitted to the receiving portion 17 via the clutch, but because the reverse rotation R2 of the receiving portion 17 is regulated by the first ratchet 18, only the pressing nut portion 13 rotates in reverse R2, and the pressing nut portion 13 can be securely tightened until the set braking force is obtained. After that, as long as the load (load torque) of the load W acts on the drum 2, the load W can continue to be held at a constant height by a braking force commensurate with the above thrust.

[0029] In this embodiment, while the motor 1 is stopped, the static friction torque of the drive system, which is indicated as the rotational resistance of the motor 1 and the reduction gear mechanism combined, is set to balance with the load torque on the drum 2 side including the stationary load W. Therefore, as long as the load W is at the planned weight, the thrust of the pressing nut portion 13 and the braking force of the clutch are maintained constant, and the load W can be held at a constant height as described above. On the other hand, if an excess load that exceeds the set braking force acts on the drum 2 side, the drive system is allowed to rotate in reverse. In this way, the drive system rotates in reverse R2 due to the excess load, thereby mitigating the impact on the device side.

[0030] Up to this point, we have focused on maintaining the load W at a constant height, because this is particularly effective in a system for delivering luggage in which the device is mounted on a drone. In other words, in a delivery system using a drone, unlike normal loading and unloading work in which the load is fixed while the drone is hovering and materials are raised and lowered on the spot (at a fixed position), there is a delivery process by unmanned flight, during which the load must be securely held (suspended) with the motor stopped. In addition, if an excess load that exceeds the braking force occurs due to an external force (wind pressure or load getting caught) during delivery, it is also necessary to absorb this. Therefore, in the present invention, as described above, these issues are addressed by setting the static friction torque of the drive system to balance the load torque on the drum side via a braking mechanism.

[0031] Next, the lifting and lowering operation of the load W will be explained. First, to lift the load W, the motor 1 is driven in the forward direction. The forward driving force of the motor 1 rotates the final output gear 11 in the forward direction R1 via two sets of planetary gears 7 and 8 and two transmission gears 9 and 10 consisting of spur gears, and the support shaft 12 integrated with the output gear 11 also rotates in the forward direction R1. When the support shaft 12 rotates in the forward direction R1, the pressing nut part 13 is displaced in the forward direction S1 on the support shaft 12 by the feed screw action of the left-handed screw. However, since the pressing nut part 13 is already completely tightened at the stage when the load W is fixed in the air, it is in a state where it can rotate together with the support shaft 12, and after the motor 1 is started, the pressing nut part 13 rotates in the forward direction R1 with almost no time lag. Such forward rotation R1 torque of the pressing nut part 13 is transmitted to the drum 2 via the second ratchet 19, and the load W is hoisted up. During this time, the clutch plate 14 and friction plate 16 are in a complete frictional connection state through the lining 15, so the load W can be reliably hoisted by the hoisting torque on the drive system side. Also, because the receiving part 17 is regulated in reverse rotation R2 by the first ratchet 18, even if the drum 2 attempts to rotate in reverse R2 while the load W is being raised, this is regulated and the drive system, including the motor 1, will not rotate in reverse R2, preventing the load W from falling.

[0032] It is not essential that this hoisting operation be started with the load W suspended in mid-air; it is of course also possible to start hoisting with the load W placed on the ground. In this case, even if the pressing nut portion 13 is positioned away from the clutch plate 16 (in other words, even if the pressing nut portion 13 is loose and the braking force is zero), the load W can be hoisted in the same manner as described above by driving the motor 1 in the forward direction. Also, even if the motor 1 is stopped midway through hoisting, the same braking force is obtained and the load W can be held at a constant height.

[0033] On the other hand, to lower the load W, the motor 1 is driven in the reverse direction. When the motor 1 is driven in the reverse direction, the final output gear 11 rotates in the reverse direction R2 via the two sets of planetary gears 7 and 8 and the two transmission gears 9 and 10, which are made up of spur gears. This causes the support shaft 12, which is integrated with the output gear 11, to rotate in the reverse direction R2. When the support shaft 12 rotates in the reverse direction R2, the pressing nut portion 13 displaces the support shaft 12 in the reverse direction S2, loosening the fastening and losing the thrust force against the clutch. In this way, the frictional joining force between the clutch plate 14 and the friction plate 16 and the lining 15 is also lost, and the braking force is released. After that, the drum 2 becomes free to rotate in the reverse direction R2, and the load W descends by natural drop.

[0034] However, the descent speed of the load W is kept almost constant. This is because, if the descent speed of the load W exceeds the payout speed of the drive system, the reverse rotation R2 speed of the drum 2 (synonymous with the reverse rotation R2 speed of the pressing nut portion 13) will exceed the reverse rotation R2 speed of the support shaft 12 (synonymous with the reverse rotation R2 speed of the drive system), and the reverse rotation R2 of the pressing nut portion 13 will relatively prevail. Then, since the pressing nut portion 13 appears to rotate reverse R2 independently by an amount corresponding to the speed difference, the support shaft 12 is tightened in the forward direction S1, a thrust force is obtained against the clutch, and the braking force is restored again. Therefore, while the motor 1 is driving in the reverse direction, the load W can be lowered by the reverse rotation R2 speed of the drive system.

[0035] Then, in the final stage, the motor 1 is stopped just as the load W lands, completing the series of operations. If the timing of stopping the motor 1 is delayed from the landing of the load W, the rope 3 is normally unwound from the drum 2 more than necessary, causing a backlash phenomenon (the tangled line caused by line fraying in fishing). However, in this embodiment, the pressing nut portion 13 is loosened at the moment that the drum 2 becomes unloaded as the load W lands. That is, the pressing nut portion 13 has been tightened to the clutch side by the load torque on the drum 2 side until then, but at the same time, it is subjected to a reaction from the clutch in the loosening direction. Therefore, when the load torque becomes zero, the pressing nut portion 13 is instantly loosened by the reaction from the clutch. When the pressing nut portion 13 is loosened in this way, the braking force of the clutch is also released (the clutch is disengaged). After that, even if the motor 1 continues to be driven in the reverse R2 direction, the pressing nut portion 13 simply rotates together with the support shaft 12 while remaining in the loose state, and since the clutch is disengaged, the power of the motor 1 is not transmitted to the drum 2, and the rope 3 is not unwound from the drum 2, so that the backlash phenomenon does not occur. Furthermore, when the drum 2 is unloaded, the component in the reverse R2 direction that engages the claw 19a of the second ratchet 19 with the teeth 19b disappears, so that only the pressing nut portion 13 rotates idly in the reverse R2 direction. Therefore, even if the timing of stopping the motor 1 is delayed after the load W lands, the pressing nut portion 13 rotates idly at the same time as the load W lands, stopping the reverse R2 direction of the drum 2, and the rope 3 is not unwound excessively, so that the backlash phenomenon can be prevented. In other words, in this embodiment, when the load torque on the drum 2 side becomes equal to or less than a certain level during the descent of the load W, the backlash phenomenon is reliably prevented by two means: the clutch being disengaged by the loosening of the pressing nut portion 13, and the disengagement of the second ratchet 19. However, the backlash phenomenon can be prevented by employing at least one of the means.

[0036] As described above, according to the electric winding device of this embodiment, the braking mechanism (feed screw mechanism and clutch) is all concentrated on the support shaft 12 of the drum 2, which contributes to making the device more compact and lightweight. Also, since the pressing nut portion 13 of the feed screw mechanism, which is the clutch actuator, is not in meshing relationship with the various gears in the reduction gear mechanism, no excessive force is applied to the meshing portions of the reduction gear mechanism when the braking force is released and restored, improving durability.

[0037] The present invention is not limited to the configuration of the above embodiment. As one example, in the above embodiment, the pressing nut portion 13 in the feed screw mechanism is a separate member from the drum 2 and is made rotatable integrally with the drum 2 by the second ratchet 19. However, since this only contributes to preventing the above-mentioned backlash phenomenon, the object of the present invention can be achieved even if the second ratchet 19 is omitted and the drum 2 and the pressing nut portion 13 are integrally configured (integrally molded).

[0038] In addition, although part of the reduction gear mechanism is constructed using two sets of planetary gears 7 and 8, the planetary gears may be a single set, and it is also possible to construct the reduction gear mechanism entirely using spur gears. [Industrial Applicability]

[0039] The present invention can be used not only in general cargo handling fields, but also in delivery services that easily and swiftly transport cargo by air by mounting it on a drone. [Explanation of symbols]

[0040] 1 Motor 2 Drums 3. Rope 4 Level Winder 5. Traverse Cam 6 Connection terminal 7·8 Planetary Gear 9·10 Transmission gear 11 Output gear 12 Support shaft (screw shaft) 12a Male thread 13 Pressing nut part 14 Clutch plate 15 Lining 16 Friction plate 17 Receiving part 18 The First Ratchet 19 The Second Ratchet W Hanging load F1~F4 Frame

Claims

1. In an electric hoisting device in which the power of a motor is transmitted to a drum through a reduction gear mechanism and then a braking mechanism, and the rotation direction of the motor is switched between forward and reverse to raise and lower a load wound around the drum, the braking mechanism comprises a screw shaft connected to the motor via the reduction gear mechanism so as to be rotatable forward and reverse, a clutch formed by alternately arranging clutch plates and friction plates on the screw shaft through a lining, and a clutch screwed between the drum and the clutch of the screw shaft so as to be tightened toward the clutch side, and the braking mechanism is driven by a thrust generated when the braking mechanism is tightened. an electric hoisting device comprising: a pressing nut portion capable of frictionally joining a clutch plate and the friction plate by the lining, the screw shaft having a male thread portion into which the pressing nut portion screws onto a support shaft inserted into the rotation center of the drum, and the pressing nut portion is provided so as to be rotatable integrally with the drum, and while the motor is stopped, the pressing nut portion rotates in the tightening direction due to a load torque on the drum side caused by the suspended load, thereby causing the clutch to exert a braking force capable of holding the suspended load at a constant height.

2. 2. The electric hoisting device according to claim 1, wherein the clutch is a multi-plate clutch consisting of multiple sets of clutch plates, linings and friction plates, and the number of sets is changeable to obtain a braking force according to the weight of the suspended load.

3. 3. An electric hoist as claimed in claim 1 or 2, further comprising a clutch receiving portion on the screw shaft facing the pressing nut portion, said receiving portion constantly restricting reverse rotation by a ratchet.

4. 4. An electric hoist as claimed in claim 1, 2 or 3, wherein when the motor is stopped, a static friction torque of the drive system, which is expressed as a rotational resistance of the motor and the reduction gear mechanism, is set so as to balance with a load torque on the drum side.

5. 5. An electric hoisting device as claimed in any one of claims 1 to 4, wherein when the load torque on the drum side falls below a certain level during descent of a suspended load by reverse driving of the motor, the pressing nut portion receives a reaction force from the clutch against the tightening, so that the tightening is loosened and the clutch is disengaged.

6. 6. The electric winding device according to claim 1, wherein the reduction gear mechanism is at least partially constituted by a planetary gear.

7. A drone equipped with the electric hoisting device according to any one of claims 1 to 6.

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