Manual chain block

Abstract

Provided is a low-cost and small-sized manual chain block for reliably transmitting torque required for releasing engagement.　This manual chain block 10 comprises: a cylindrical driving member 14 having a driving shaft 8 on which a male thread 8a is formed, and a small-diameter part 14b and a large-diameter part 14c having a female thread 14a and interposed in a center part of a hand wheel 7; a biasing means 16 for biasing the hand wheel 7 toward the driving member 14 in a state in which the hand wheel 7 is held between friction plates F1, F2; a pressing plate 15 for transmitting biasing force to the friction plate F2; and a brake mechanism 20 pressed by a fastening force generated by threading of the male thread 8a and the female thread 14a. The manual chain block has a recessed part 19a gradually increasing in depth along an outer peripheral surface of the large-diameter part 14c, and a rolling member 19b. When rotated in a winding-up direction, the rolling member rolls toward a deep side and allows relative rotation of the hand wheel 7, and when rotated in a winding-down direction, the rolling member rolls toward a shallow side and the rolling member 19b is engaged to restrain relative rotation of the hand wheel 7.

Description

Manual Chain Hoist

[0001] The present invention relates to a manual chain block.

[0002] The hand wheel of a manual chain hoist that can prevent overload is clamped between a pair of friction plates on both axial sides and rotates integrally with the friction plates. When a rotational force from the hand chain is input to the hand wheel that exceeds the torque that can be transmitted by the friction surfaces of the friction plates, the friction surfaces slip, preventing the input of an excessive load.

[0003] The friction plate transmits the rotational force input from the hand wheel on both the surface on the hand wheel side and the surface on the opposite side facing the support member, so the hand wheel transmits the rotational force of the hand wheel on a total of four friction surfaces due to the pair of friction plates.

[0004] In this case, an overload is applied to the hand wheel in the winding direction, and the male thread of the drive shaft and the drive member having a female thread that screws into the male thread may become excessively tightened and jammed. If jamming occurs, the hand wheel may spin freely when rotating in the lowering direction, making it impossible to release the jamming. In response to this problem, Patent Document 1 discloses a technology in which a reverse rotation prevention connection is provided on the inner circumference of the hand wheel.

[0005] Special Publication No. 49-041781

[0006] Patent Document 1 discloses a reverse rotation prevention connection part consisting of a recess, an engagement slope, and a roller, which is provided between the outer periphery of the brake presser and the inner periphery of the hand chain pulley in a type in which the hand chain pulley is sandwiched between two friction plates on both sides and braked on four sides. In the reverse rotation prevention connection part, when the hand chain pulley is rotated in the lowering direction, the roller engages with the engagement slope. This allows the load to be lowered more reliably by releasing the engagement even in situations where the hand wheel spins freely.

[0007] However, since the reverse rotation prevention connection portion is provided on the hand wheel, it must be machined into a special shape, which increases the number of steps required to machine the hand wheel, thereby increasing manufacturing costs.

[0008] The present invention has been made in consideration of the above circumstances, and has as its object to provide a low-cost, small-sized manual chain hoist that reliably transmits the torque required to release the bite during a hoisting-down operation.

[0009] A manual chain block according to one aspect of the present invention includes a hand wheel having an open center and around which a hand chain is wound to be manually pulled by an operator; a drive shaft having the same center of rotation as the hand wheel and a threaded portion having a male thread formed on its outer periphery; a cylindrical drive member having, in order from one axial end side, a small diameter portion interposed in the center of the hand wheel and a female thread on its inner periphery that meshes with the male thread; and a large diameter portion having a diameter larger than the small diameter portion; a biasing means for biasing the drive member with the hand wheel sandwiched between friction plates from both axial sides; a presser plate for transmitting the biasing force of the biasing means to the friction plate adjacent to the biasing means; and a brake plate pressed by the surface of the large diameter portion on the other axial end side of the hand wheel. and a brake mechanism that is pressed by a tightening force generated by the engagement of the male and female threads as the hand wheel rotates. The drive member has a recess formed on the outer peripheral surface of the large diameter part of the drive member, the radial depth of which gradually increases along the circumferential direction, and a rolling member that is housed in the recess so that it can roll along the circumferential direction. When the hand wheel is rotated in the winding direction by pulling the handwheel by hand, the rolling member rolls in the direction of increasing depth, allowing relative rotation between the inner and outer peripheral surfaces of the hand wheel, and when the hand wheel is rotated in the unwinding direction by pulling the handwheel by hand, the rolling member rolls in the direction of decreasing depth, and the rolling member becomes engaged between the inner peripheral surface of the hand wheel and the recess, preventing relative rotation.

[0010] According to the present invention, it is possible to reliably transmit the torque required to release the jamming during the lowering operation and to provide a low-cost, small-sized manual chain hoist.

[0011] Fig. 1 is a cross-sectional view showing the overall configuration of a manual chain block according to this embodiment. Fig. 2 is a partially enlarged cross-sectional view showing an enlarged area A of the manual chain block according to this embodiment. Fig. 3 is a perspective view showing how a drive member and a friction plate are fitted together. Fig. 4 is a perspective view showing how a presser plate and a friction plate are fitted together. Fig. 5 is a perspective view showing a drive member. Fig. 6 is a partial cross-sectional view showing the one-way clutch as seen from the direction of the arrows, with the hand wheel cut along line X-X in Fig. 2.

[0012] The manual chain block 10 according to this embodiment will be described below with reference to the drawings. In the following description, "axial direction" refers to the direction along the axis of the drive shaft 8, "one axial end" refers to the end of the drive shaft 8 that is on the hand wheel 7 side, and "the other axial end" refers to the opposite side of the one axial end.

[0013] [Structure] FIG. 1 is a cross-sectional view showing the overall configuration of a manual chain block 10 according to this embodiment.

[0014] The manual chain block 10 comprises a chain block body 1, an upper hook 2, a load sheave (not shown), a load chain 4, a lower hook 5, a hand chain 6, a hand wheel 7, and a drive shaft 8.

[0015] The chain block body 1 has a first frame 11, a second frame 12, and a third frame 13, and is formed by stacking the frames 11, 12, and 13 in this order and fastening them with bolts. The first frame 11, the second frame 12, and the third frame 13 are each formed by aluminum die-casting.

[0016] The upper hook 2 is located at the top of the chain block body 1 and is hooked onto a beam or the like of a structure (not shown) to suspend the manual chain block 10. The upper hook 2 has a hook hole (not shown) formed in the bottom, and is connected to the chain block body 1 by inserting a hanging shaft (not shown) that extends through the first frame 11 and the second frame 12 and partway up the third frame 13 into the hook hole.

[0017] The load sheave is rotatably sandwiched between the first frame 11 and the second frame 12, and the load chain 4 is wound around it. The load chain 4 has a lower hook 5 connected to its lower end, and supports the weight of a load suspended from the lower hook 5. The load sheave pays out the load chain 4 according to its rotation direction, raising and lowering the load.

[0018] The hand wheel 7 rotates around a drive shaft 8 supported by a first frame 11 and a second frame 12 via ball bearings 9, and the hand chain 6 is looped around the drive shaft 8. The hand chain 6 is unwound from the hand wheel 7, and the operator can pull it manually to rotate the hand wheel 7.

[0019] The rotation of the hand wheel 7 is transmitted from the drive shaft 8 via the drive member 14 (described later) to the reduction gear mechanism 24, where it is reduced in speed and transmitted to the load sheave. The rotation direction of the load sheave is synchronized with the rotation direction of the hand wheel 7, and the load chain 4 is reeled out or reeled back depending on the rotation direction of the hand wheel 7, thereby raising or lowering the load.

[0020] The drive shaft 8 is a rotating member that passes through the chain block body 1 and is rotatably supported by ball bearings 9 provided on the first frame 11 and the second frame 12. The drive shaft 8 is located at the center of the hand wheel 7 and functions as the rotation axis of the hand wheel 7.

[0021] (Detailed Structure) Next, a description will be given of the structure of the portion of the manual chain block 10 that transmits the rotational force of the hand wheel 7 to the drive shaft 8. Fig. 2 is an enlarged partial cross-sectional view showing an enlarged area A in Fig. 1 .

[0022] The drive shaft 8 has, in this order from one axial end, a threaded portion 8b having a male thread 8a formed on its outer periphery, a step portion 8c having a larger diameter than the threaded portion 8b, and a flange portion 8d having a larger diameter than the step portion 8c. The threaded portion 8b further has a bolt portion 8e formed at one axial end thereof and a threaded portion 8f that threadably engages with the female thread 14a of the drive member 14.

[0023] The drive member 14 is a cylindrical member that transmits the rotational force of the hand wheel 7 to the drive shaft 8. The drive member 14 has, in order from one axial end, a small-diameter portion 14b with an internal thread 14a that threads with the external thread 8a of the threaded portion 8f of the drive shaft 8. The small-diameter portion 14b is fitted inside the reduced-diameter portion 7b of the hand wheel 7 and has a larger diameter than the small-diameter portion 14b. The inner periphery of the drive member 14, facing the bolt portion 8e of the drive shaft 8, is provided with a space 14g for accommodating a groove nut 18. The small-diameter portion 14b has a slit 14f along the axial direction along a portion of its circumference (FIG. 5). Furthermore, the portion of the small-diameter portion 14b on the outer diameter side where the slit 14f is located has an external thread 14h that threads with a spring nut 17. A groove nut 18 that screws onto the bolt portion 8e of the drive shaft 8 is provided on one axial end of the drive member 14, preventing the hand wheel 7 from falling off during the winding-down operation.

[0024] The hand wheel 7 is manufactured by casting and has an inner periphery 7a and a reduced diameter portion 7b that protrudes further inward from the inner periphery 7a to form a hole serving as a minimum diameter portion. Friction plates F1 and F2 are provided on both axial sides of the reduced diameter portion 7b of the hand wheel 7 so as to be in sliding contact with the reduced diameter portion 7b. Furthermore, a large diameter portion 14c of a drive member 14 is disposed on the other axial end of the reduced diameter portion 7b so as to sandwich the reduced diameter portion 7b and the friction plate F1. Meanwhile, a presser plate 15 is disposed on one axial end of the reduced diameter portion 7b so as to sandwich the reduced diameter portion 7b and the friction plate F2.

[0025] The hand wheel 7 further has a chain pocket 71 on the outer periphery. The chain pocket 71 is a portion into which the metal ring 6a of the hand chain 6 is fitted, and includes a horizontal pocket (not shown) into which the metal ring 6a is fitted with the flattened direction of the metal ring 6a parallel to the axis, and a vertical pocket (not shown) that is deeper than the horizontal pocket and into which the metal ring 6a is fitted with the flattened direction of the metal ring 6a intersecting the axis.

[0026] The opening diameter of the inner peripheral portion 7a of the hand wheel 7 is large enough so that the outer circumferential surface of the large diameter portion 14c of the driving member 14 does not slide on the inner peripheral portion 7a of the hand wheel 7 even when the hand wheel 7 and the driving member 14 rotate relative to each other. Furthermore, the opening diameter is large enough so that cylindrical rollers 19b (described later) can mesh with recesses 19a of the driving member 14 (described later) and the inner peripheral portion 7a of the hand wheel 7. The opening depth of the inner peripheral portion 7a of the hand wheel 7 is set deep enough to accommodate the friction plate F1 and the large diameter portion 14c of the driving member 14.

[0027] The pressing plate 15 is a ring-shaped plate that supports the base end of the disc spring 16, and the biasing force of the disc spring 16 is adjusted by the tightening force of a spring locking nut 17 that is provided on one axial end of the disc spring 16. The tightening force of the spring locking nut 17 is adjusted so that the hand wheel 7 will spin freely when an operating force for the hand chain 6 that is 1.05 to 2 times the operating force for the hand chain 6 required to lift a load of the rated load is input to the hand wheel 7.

[0028] A brake mechanism 20 is provided on the outer periphery of the drive shaft 8 from the step 8c to the flange 8d. The brake mechanism 20 has the step 8c and flange 8d of the drive shaft 8, a pair of brake plates B interposed on the outer periphery of the step 8c, a ratchet wheel 22 held between the brake plates B and attached to the inner periphery via a bushing 21, and a claw 23 that meshes with the ratchet wheel 22 to prevent the ratchet wheel 22 from rotating in the winding-down direction.

[0029] When the drive shaft 8 rotates in the lowering direction relative to the drive member 14, the brake mechanism 20 is pressed axially against the drive member 14 due to the engagement between the male thread 8a and the female thread 14a, thereby exerting a braking force. On the other hand, when the hand wheel 7 rotates in the lowering direction, the brake mechanism 20 releases the braking force acting to prevent the load from dropping by causing the large diameter portion 14c to separate from the brake plate B due to the engagement between the male thread 8a and the female thread 14a. As a result, when the drive shaft 8 rotates due to the load of the suspended load, the male thread 8a and the female thread 14a are screwed together, and the large diameter portion 14c is again pressed axially against the brake plate B, causing the brake mechanism 20 to exert a braking force. Thereafter, the application and release of the braking force by the brake mechanism 20 is repeatedly switched as described above depending on the rotation direction of the hand wheel 7.

[0030] In other words, when the hand wheel 7 receives the operating force of the operator from the hand chain 6 and rotates forward in the winding direction, the small diameter portion 14b of the drive member 14 moves toward the other axial end while threading into the threaded portion 8f of the drive shaft 8, and the large diameter portion 14c of the drive member 14 presses the brake plate B toward the other axial end, thereby dynamically connecting the hand wheel 7 and the drive shaft 8.

[0031] Furthermore, when the hand wheel 7 receives the operating force of the operator via the hand chain 6 and rotates in the reverse direction in the lowering direction, the small diameter portion 14b of the drive member 14 moves toward one axial end while threadedly engaging with the threaded portion 8f of the drive shaft 8, and the pressure applied by the large diameter portion 14c of the drive member 14 to the ratchet wheel 22 and brake plate B is released, and the braking action is released. Therefore, the hand wheel 7 rotates in the lowering direction due to the operating force of the operator.

[0032] (Friction Plate Anti-Rotation) Next, a description will be given of the structure of the driving member 14 and the friction plate F1 that abuts against the driving member 14. Fig. 3 is a perspective view showing how the driving member 14 and the friction plate F1 are fitted together.

[0033] The drive member 14 has an annular large-diameter surface 14d that is the boundary between the large-diameter portion 14c and the small-diameter portion 14b and extends vertically in the plane of the drawing in Fig. 2. The drive member 14 has three protrusions 14e that protrude from the large-diameter surface 14d and are located around the circumferential edge on the radially outer side. The protrusions 14e protrude axially from the large-diameter surface 14d and are arranged at equal intervals from each other along the circumferential direction.

[0034] The friction plate F1 is an annular member having a circular hole F1a on its inner periphery, the inner diameter of which is slightly larger than the outer diameter of the small diameter portion 14b of the drive member 14. The friction plate F1 has three notches F1b on its outer periphery along the circumferential direction. The notches F1b are recessed inward from the outer periphery and are arranged at equal intervals along the circumferential direction.

[0035] The friction plate F1 is fitted so that the small diameter portion 14b of the drive member 14 is inserted into the hole F1a of the friction plate F1. At this time, the drive member 14 is attached so that the protrusion 14e fits into the notch F1b of the friction plate F1. As a result, even if a force is applied in a direction that causes relative rotation between the drive member 14 and the friction plate F1, relative rotation can be prevented because the protrusions 14e of the drive member 14 fit into the notches F1b of the friction plate F1 at three points in the circumferential direction.

[0036] Next, a description will be given of the structure of the presser plate 15 and the friction plate F2 that abuts against the presser plate 15. Fig. 4 is a perspective view showing how the presser plate 15 and the friction plate F2 are fitted together.

[0037] The presser plate 15 is an annular member having a circular hole 15a on its inner periphery, with an inner diameter slightly larger than the outer diameter of the small-diameter portion 14b of the drive member 14, and a detent 15b protruding inward from the circumferential surface of the circular hole 15a. The presser plate 15 has an annular presser surface 15c, which abuts against the friction plate F2 and extends vertically in the plane of the drawing in FIG. 2, on the axially opposite side of the surface that abuts the disc spring 16 (FIG. 2). Three protrusions 15d protrude circumferentially from the outer edge of the presser surface 15c in the radially outer direction. The protrusions 15d protrude axially from the presser surface 15c and are spaced equally apart from one another in the circumferential direction.

[0038] The friction plate F2 is an annular member having a circular hole F2a on its inner periphery, the inner diameter of which is slightly larger than the outer diameter of the small diameter portion 14b of the drive member 14. The friction plate F2 has three notches F2b on its outer periphery along the circumferential direction. The notches F2b are recessed inward from the outer periphery and are arranged at equal intervals along the circumferential direction.

[0039] The presser plate 15 is attached so that the small diameter portion 14b of the drive member 14 is inserted through the hole 15a of the presser plate 15 and the rotation stopper 15b of the presser plate 15 fits into the slit 14f (Fig. 3) along the axial direction of the drive member 14. As a result, even if a force is applied in a direction that rotates the drive member 14 relative to the presser plate 15 via the friction plate F1, hand wheel 7, and friction plate F2, the relative rotation can be prevented because the rotation stopper 15b of the presser plate 15 fits into the slit 14f of the drive member.

[0040] The protrusions 15d of the presser plate 15 are attached to fit into the notches F2b of the friction plate F2. As a result, even if a force is applied in a direction that rotates the presser plate 15 and the friction plate F2 relative to each other, the protrusions 15d of the presser plate 15 fit into the notches F2b of the friction plate F2 at three points in the circumferential direction, preventing the relative rotation.

[0041] In this way, the friction plates F1, F2 on both axial sides of the hand wheel 7 cannot rotate relative to the adjacent drive member 14 or presser plate 15, so if an overload is applied to the hand wheel 7 and a force greater than the friction force generated between the hand wheel 7 and the friction plates F1, F2 is input, only one side of each of the friction plates F1, F2 will spin freely. This makes it possible to prevent damage to the chain block body 1, reduction gear mechanism 24, etc. due to the application of a load greater than expected.

[0042] (One-way clutch) Next, the one-way clutch 19 attached to the drive member 14 will be described. Figure 5 is a perspective view showing the drive member 14 and the one-way clutch 19 having cylindrical rollers 19b. Figure 6 is a partial cross-sectional view of the hand wheel 7 cut along line X-X in Figure 2, showing the one-way clutch 19 as viewed from the direction of the arrow.

[0043] The one-way clutch 19 has a recess 19a formed along the outer circumferential surface of the large diameter portion 14c of the driving member 14, and a cylindrical roller 19b as a rolling member that can roll within the recess 19a.

[0044] The outer periphery of the large diameter portion 14c of the driving member 14 is arranged concentrically with the inner periphery 7a of the hand wheel 7. As shown in Figure 5, the driving member 14 has a recess 19a formed on the outer periphery of the large diameter portion 14c, and a cylindrical roller 19b is arranged in the recess 19a so as to be able to roll.

[0045] The recess 19a is a recess whose radial depth gradually increases toward one circumferential side of the large-diameter portion 14c, that is, an increasing dent. The recess 19a is open toward the small-diameter portion 14b, which is one axial end, and closed toward the other axial end. The cylindrical roller 19b is provided within the recess 19a so as to face the same axial direction as the large-diameter portion 14c. The diameter of the cylindrical roller 19b is set to be slightly smaller than the depth of the deepest part of the recess 19a.

[0046] As shown by the arrow in Figure 6, when the hand wheel 7 rotates in the winding direction, the cylindrical rollers 19b roll and spin freely in the deepest part of the recessed portion 19a, and do not protrude radially outward beyond the outer periphery of the large-diameter portion 14c. This allows free relative rotation between the large-diameter portion 14c and the hand wheel 7 located on its outer periphery. Therefore, when the hand wheel 7 is rotated in the winding direction, the one-way clutch 19 is in a disengaged state.

[0047] On the other hand, as shown by the arrow in Figure 6, when the hand wheel 7 rotates in the lowering direction, the cylindrical rollers 19b are dragged by the hand wheel 7 and roll circumferentially within the recessed portion 19a toward a shallower radial depth. As the cylindrical rollers 19b roll, the portion of the cylindrical rollers 19b that protrudes radially outward from the recessed portion 19a increases. The size of the protruding portion increases the more the cylindrical rollers 19b roll. As a result, the inner periphery of the hand wheel 7 and the outer periphery of the large diameter portion 14c are interlocked with each other through the cylindrical rollers 19b, preventing relative circumferential movement between them. Therefore, when the hand wheel 7 is rotated in the lowering direction, the one-way clutch 19 is in an engaged state.

[0048] In this way, the hand wheel 7 and the large diameter portion 14c are structured not to rotate relative to each other when the hand wheel 7 is rotated in the lowering direction, so even if an overload is input to the hand wheel 7 and the female thread 14a of the drive member 14 and the male thread 8a of the drive shaft 8 are excessively tightened and become jammed, the large diameter portion 14c can rotate together with the rotation of the hand wheel 7 in the lowering direction. Therefore, the friction plate F1 sandwiched between the reduced diameter portion 7b and the large diameter portion 14c of the hand wheel 7 can be prevented from rotating freely, and the hand wheel 7 can be prevented from rotating freely.

[0049] The radial width of the protrusions 14e provided on the drive member 14 and the radial depth of the recesses 19a are set to be equal from the outer circumferential surface of the large-diameter portion 14c. That is, the radially inner position of the protrusions 14e and the deepest portion of the recesses 19a are located on the same diameter. This ensures that the friction plate F1 has a sufficient friction surface on the radially inner side, preventing damage to the friction plate F1 (FIG. 3). Furthermore, the protrusions 14e and the recesses 19a are alternately and evenly positioned along the circumferential direction of the outer periphery.

[0050] Furthermore, because the recess 19a is located in the large diameter portion 14c, the force acting on the hand wheel 7 by the cylindrical roller 19b is reduced, preventing the cylindrical roller 19b from biting into the hand wheel 7 and the driving member 14. This makes it possible to stably transmit a larger torque from the hand wheel 7 to the driving member 14 without damaging any parts.

[0051] The drive member 14 is manufactured by sintering, and the projections 14e and recesses 19a are formed without machining. However, the manufacturing method may be casting instead of sintering. Because the projections 14e for preventing relative rotation of the friction plate F1 and the recesses 19a of the reverse stop connection are molded together on the drive member, there is no need to provide a reverse stop connection on the hand wheel 7, and the chain block body 1 can be manufactured at low cost.

[0052] [Operation] The operation of the manual chain block 10 of this embodiment will be described below with particular reference to FIG.

[0053] When an operator manually pulls the hand chain 6 to lift a load, the hand wheel 7 rotates forward in the hoisting direction. As the hand wheel 7 rotates, the female thread 14a of the drive member 14, located on the inner periphery of the hand wheel 7, engages with the male thread 8a of the threaded portion 8f of the drive shaft 8, moving the drive member 14 to the other axial end. The large-diameter portion 14c of the drive member 14 presses against the brake plate B, forcing the ratchet wheel 22 and the brake plates B, located on both axial sides of it, into pressure contact between the large-diameter portion 14c and the flange portion 8d of the drive shaft 8. This causes the entire system, from the hand wheel 7 to the brake mechanism 20, to rotate around the drive shaft 8 as a single unit.

[0054] When a worker releases his / her hand from the hand chain 6 during lifting a load, a reverse rotation force acts on the drive shaft 8, but the reverse rotation of the ratchet wheel 22 is stopped by the claw part 23 meshing with the ratchet wheel 22, so the load is suspended in the air at the position where the worker releases his / her hand.

[0055] When a worker lifts a load that is heavier than the expected load, a torque greater than the friction force generated between the hand wheel 7 and the friction plates F1, F2 is input to the hand wheel 7 from the hand chain 6, causing sliding on a total of two surfaces, the hand wheel 7 and the friction plates F1, F2. This causes the hand wheel 7 to spin freely. Because the hand wheel 7 slides on a total of two surfaces, the friction force is more stable than, for example, when sliding on four surfaces, and the torque value at which the hand wheel 7 spins freely is a stable value.

[0056] Furthermore, if an excessive load is applied to the hand wheel 7 when a worker lifts a load, the female thread 14a of the drive member 14 arranged on the inner periphery of the hand wheel 7 and the male thread 8a of the threaded portion 8f of the drive shaft 8 will thread together, and the drive member 14 will move to the other axial end, causing the large diameter portion 14c of the drive member 14 to press against the brake plate B. At this time, if the pressing force becomes excessive and the reaction force acts on the threaded portion between the female thread 14a of the drive member 14 and the male thread 8a of the threaded portion 8f of the drive shaft 8, the threaded portion 8f may become stuck.

[0057] Once the threaded portion 8f is caught, the worker manually pulls the hand chain 6 in the lowering direction to lower the load, causing the hand wheel 7 to rotate in the reverse direction. At this time, the hand wheel slides on two surfaces, friction plates F1 and F2, which may cause the hand wheel 7 to spin freely, making it impossible to lower the suspended load.

[0058] A one-way clutch 19 is provided on the outer periphery of the large-diameter portion 14c of the drive member 14, which acts between the inner periphery 7a of the hand wheel 7. When the hand wheel 7 is rotated in the lowering direction after the threaded portion 8f has engaged, the one-way clutch 19 engages, preventing the drive member 14 and the hand wheel 7 from rotating relative to each other. Furthermore, relative rotation between the large-diameter portion 14c and the protrusion 15d of the presser plate 15 and the notches F1b and F2b of the friction plates F1 and F2 is prevented, so sliding occurs on two surfaces rather than four. As a result, the hand wheel 7 does not spin freely at torque values ​​that are significantly smaller than the expected torque value, and therefore, the hand wheel 7 is more reliably prevented from spinning freely.

[0059] [Modifications] In the above embodiment, in addition to the anti-rotation structure formed by the large diameter portion 14c, the protrusions 14e, 15d of the pressing plate 15, and the notches F1b, F2b of the friction plates F1, F2, the anti-rotation structure of the one-way clutch 19 is also added, but only one of the anti-rotation structures may be applied as long as it can prevent the hand wheel 7 from spinning freely.

[0060] In the above embodiment, the large diameter portion 14c and the presser plate 15 each have three protrusions 14e, 15d, but the number of protrusions 14e, 15d may be any number greater than or equal to one as long as slippage between the hand wheel 7 and the friction plates F1, F2 can be prevented. Furthermore, the numbers of protrusions 14e, 15d provided on the large diameter portion 14c and the presser plate 15 may be different. When changing the number of protrusions 14e, 15d as described above, it is necessary to change the number and positions of the notches F1b, F2b on the friction plates F1, F2 that correspond to the protrusions 14e, 15d.

[0061] In the above embodiment, the protrusions 14e, 15d are provided at equal positions along the circumferential direction of the large diameter portion 14c and the presser plate 15, but they do not have to be evenly spaced along the circumferential direction.

[0062] In addition, in the above embodiment, the outer periphery of the large diameter portion 14c of the driving member 14 has three recesses 19a, but the number of recesses 19a may be any number greater than or equal to one as long as slippage between the hand wheel 7 and the friction plates F1 and F2 can be prevented.

[0063] In the above embodiment, the recesses 19a are provided at equal positions along the circumferential direction of the outer periphery of the large diameter portion 14c. However, if two or more recesses 19a are provided, they do not have to be evenly spaced along the circumferential direction.

[0064] In the above embodiment, the disc spring 16 exerts a biasing force to press the inner peripheral portion 7a of the hand wheel 7 against the friction plates F1, F2 on either side of it. However, other members may be used as long as they can exert a biasing force sufficient to prevent slippage between the hand wheel 7 and the friction plates F1, F2 during normal rotation of the hand wheel 7.

[0065] Furthermore, in the above embodiment, the relative rotation between the drive member 14 and the friction plate F1, and between the pressure plate 15 and the friction plate F2 is suppressed by the projections on the drive member 14 and the pressure plate 15 matching with the notches F1b and F2b on the friction plates F1 and F2, respectively. However, the relative rotation between the drive member 14 and the friction plate F1, and between the pressure plate 15 and the friction plate F2 may also be suppressed by bonding them together, for example, with an adhesive or the like.

[0066] [Supplementary Explanation of the Embodiments] The above-described embodiments each show a preferred specific example of the present invention. The numerical values, components, arrangement positions of the components, order of connection, etc. shown in the above-described embodiments are merely examples and are not intended to limit the present invention. Furthermore, the drawings are not necessarily strict illustrations.

[0067] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0068] [Additional Notes] The contents of the above-described embodiments can be understood, for example, as follows.

[0069] (1) The one-way clutch manual chain hoist 10 includes a hand wheel 7 having an open center and around which a hand chain 6 is looped and which is manually operated by an operator; a drive shaft 8 having a threaded portion 8b with a male thread 8a formed on its outer periphery, which has the same center of rotation as the hand wheel 7; a cylindrical drive member 14 having a female thread 14a on its inner periphery that is engaged with the male thread 8a, a small diameter portion 14b disposed in the center of the hand wheel 7, and a large diameter portion 14c having a diameter larger than the small diameter portion 14b, in that order from one axial end; a biasing means 16 that biases the drive member 14 while the hand wheel 7 is sandwiched between friction plates F1 and F2 on both axial sides; a presser plate 15 that transmits the biasing force of the biasing means 16 to the friction plate F2 adjacent to the biasing means 16; and a brake plate B that is pressed against the surface of the other axial end of the large diameter portion 14c. and a brake mechanism 20 that is pressed by a tightening force generated by the engagement of the male thread 8a and the female thread 14a as the hand wheel 7 is rotated. The drive member 14 has a recess 19a that is formed on the outer peripheral surface of the large diameter portion 14c of the drive member 14 and whose radial depth gradually increases along the circumferential direction, and a cylindrical roller 19b that is accommodated in the recess 19a so as to be able to roll along the circumferential direction. When the hand wheel 7 is rotated in the winding direction by a pulling operation, the cylindrical roller 19b rolls in the direction of increasing depth, allowing relative rotation between the inner and outer peripheral surfaces of the hand wheel 7, and when the hand wheel 7 is rotated in the winding down direction by a pulling operation, the cylindrical roller 19b rolls in the direction of decreasing depth, and the cylindrical roller 19b is engaged between the inner peripheral surface of the hand wheel 7 and the recess, preventing relative rotation.

[0070] As a result, recesses 19a are formed in the large diameter portion 14c of the drive member 14, and cylindrical rollers 19b roll within the recesses 19a, thereby configuring the one-way clutch 19 at a large diameter position, making it possible to transmit a larger torque than when the one-way clutch 19 is configured on the inner peripheral side of the hand wheel 7. Therefore, even if an overload is input to the hand wheel 7 and the female thread 14a of the drive member 14 and the male thread 8a of the drive shaft 8 are excessively tightened and become jammed, idling of the hand wheel 7 in the lowering direction can be prevented, and the lowering operation can be performed more reliably. This improves the operability of the operator.

[0071] (2) Positional Relationship of the One-Way Clutch The recesses 19a of the driving member 14 may be provided at equal positions along the circumferential direction on the outer circumferential surface of the large diameter portion 14c.

[0072] As a result, when a force acts between the inner peripheral portion 7a of the hand wheel 7 and the large diameter portion 14c of the drive member 14 in a direction that causes relative rotation, the force that stops the relative rotation acts alternately along the circumferential direction of the outer periphery of the large diameter portion 14c, so the force that the recesses 19a receive can be efficiently dispersed. This prevents damage such as breakage of the cylindrical rollers 19b and chipping of the recesses 19a, and more reliably prevents the hand wheel 7 from spinning freely.

[0073] (3) Along the outer periphery of the surface of the one-way and the large diameter portion 14c of the protrusion drive member 14 that abuts against the friction plate F1, one or more protrusions 14e may be provided toward one axial end.

[0074] This prevents relative rotation between the friction plate F1 and the drive member 14, and the friction plate F1 slides only against the hand wheel 7, stabilizing the torque transmitted between the drive member 14 and the hand wheel 7 and preventing excessive torque from being applied. Also, like the recess 19a of the drive member 14, the protrusion 14e is provided along the outer periphery of the large diameter portion 14c, ensuring a sufficient friction surface for the friction plate F1 and preventing damage to the friction plate F1. Furthermore, because both the recess 19a and the protrusion 14e are provided on the drive member 14, the manual chain hoist 10 can be manufactured at low cost.

[0075] (4) Manufacturing Method The recess 19a of the driving member 14 may also be manufactured by sintering.

[0076] This allows the recess 19a to be formed with high precision, and simplifies the manufacturing process since secondary processing is not required.

[0077] DESCRIPTION OF SYMBOLS 6 Hand chain 7 Hand wheel 8 Drive shaft 8a Male thread 8b Threaded portion 8c Step portion 8d Flange portion 10 Manual chain block 14 Drive member 14a Female thread 14b Small diameter portion 14c Large diameter portion 14e Projection 14f Slit 14h Male thread 15 Presser plate 15d Projection 16 Disc spring (biasing means) 19a Recess 19b Cylindrical roller (rolling member) 19g Recess 20 Brake mechanism B Brake plate F1 Friction plate F1b Notch F2 Friction plate F2b Notch

Claims

1. A device comprising: a hand wheel with an open center and a hand chain around which a worker can pull the hand chain; a drive shaft having the same center of rotation as the hand wheel and a threaded portion with a male thread formed on its outer periphery; a cylindrical drive member having a female thread on its inner periphery that meshes with the male thread, and having, from one axial end, a small diameter portion disposed in the center of the hand wheel, and a large diameter portion having a diameter larger than the small diameter portion; a biasing means that biases the drive member while the hand wheel is sandwiched between friction plates on both axial sides; a presser plate that transmits the biasing force of the biasing means to the friction plate adjacent to the biasing means; and a brake mechanism having a brake plate that is pressed by the surface of the large diameter portion on the other axial end side, and that is pressed by a clamping force generated by the engagement of the male thread with the female thread as the hand wheel rotates. a recess formed on the outer peripheral surface of the large diameter portion of the drive member, the radial depth of which gradually increases along the circumferential direction, and a rolling member housed in the recess so as to be able to roll along the circumferential direction; when the hand wheel is rotated in the winding-up direction by a pulling operation, the rolling member rolls in the direction toward the deeper depth, allowing relative rotation between the inner peripheral surface and the outer peripheral surface of the hand wheel; and when the hand wheel is rotated in the winding-down direction by a pulling operation, the rolling member rolls in the direction toward the shallower depth, causing the rolling member to become engaged between the inner peripheral surface of the hand wheel and the recess, preventing relative rotation.

2. A manual chain block according to claim 1, wherein the recesses of the drive member are provided at equal positions along the circumferential direction on the outer circumferential surface of the large diameter portion.

3. A manual chain block as claimed in claim 1, wherein the drive member has one or more protrusions towards one axial end along the outer periphery of the surface of the large diameter portion that abuts against the friction plate.

4. A manual chain block according to any one of claims 1 to 3, characterized in that the recess of the drive member is manufactured by sintering.

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