Overspeed detecting device

Abstract

To provide an overwind detecting device capable of preventing the occurrence of a trouble caused by the sagging of a weight suspending member during overwind.SOLUTION: An overwind detection device 100 for a hoisting wire 12 that suspends a suspended load via a suspended load support part 2 includes a ring-shaped weight 110 through which the hoisting wire 12 passes, a weight suspension member 120 that suspends the weight 110, and an overwind detection part 130 that detects push-up of the weight 110 by the suspended load support part 2 when the hoisting wire 12 is overwound, wherein the weight suspension member 120 includes a bendable link mechanism. The link mechanism normally maintains an extended attitude by the weight of the weight 110, and when the hoisting wire 12 is excessively wound, the link mechanism changes to a bent attitude as the weight 110 is pushed up by the suspended load support part 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an overwind detection device. [Background technology]

[0002] Patent Document 1 discloses an overwinding detection device (overwinding prevention device) that is applied to a crane and detects overwinding of a hoisting wire. A widely known overwinding detection device is a weight-type overwinding detection device that includes a ring-shaped weight through which the hoisting wire passes, a weight wire that suspends the weight, and an overwinding detection unit that detects the weight being pushed up by the load support unit when the hoisting wire is overwinded.

[0003] Since there is a time lag between the detection of overwinding by the overwinding detector and the stopping of the load support part, in cranes with fast hoisting speeds, it is necessary to quickly detect the approach of the load support part to the overwinding area. In such cases, the general solution is to lengthen the weight wire 202 so that the position of the weight 201 is lowered, as shown in Figure 7(a). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 63-197294 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the weight wire 202 is made longer, the weight wire 202 will sag more when over-wound, and as shown in Figure 7(b), there is a risk that the slack weight wire 202 will hang down and get caught on a protrusion 204 of the load support part 203. If the crane operator lowers the load support part 203 without noticing that the weight wire 202 has been caught, there is a possibility that the over-winding detection part (for example, a limit switch) will be pulled by the weight wire 202 and may be damaged or fall.

[0006] Therefore, an object of the present disclosure is to provide an overwinding detection device that can prevent problems caused by the sagging of a weight suspending member during overwinding. [Means for solving the problem]

[0007] In one aspect, the following solution is provided.

[0008] An overwinding detection device for a hoisting wire that suspends a load via a load support part, a ring-shaped weight through which the winding wire passes; a weight suspending member for suspending the weight; an overwinding detection unit that detects the lifting of the weight by the load support unit when the hoisting wire is overwound, The weight suspending member is configured by a bendable and extendable link mechanism, The link mechanism is characterized in that it normally maintains an extended position due to the weight of the weight, and when the hoisting wire is overwound, it changes to a bent position as the weight is pushed up by the load support part. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to prevent problems caused by the hanging of the weight suspending member during over-winding. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an overall view of a crane to which an over-hoisting detection device according to an embodiment of the present invention is applied. [Figure 2] 1 is a perspective view of a main part of a crane showing a normal state of an overwinding detection device according to a first embodiment. FIG. [Figure 3] 1 is a perspective view of a main part of a crane, illustrating a state in which an overwinding detection device according to a first embodiment is overwinded. FIG. [Figure 4] 1A and 1B are diagrams showing the structure of the overwinding detection unit, in which FIG. 1A shows the overwinding detection unit under normal conditions, and FIG. 1B shows the overwinding detection unit under overwinding conditions. [Figure 5] FIG. 10 is a perspective view of the main part of a crane showing a normal state of an overwinding detection device according to a second embodiment. [Figure 6] FIG. 10 is a perspective view of the main part of a crane, showing a state in which an overwinding detection device according to a second embodiment is overwinded. [Figure 7] 1A and 1B are perspective views of the essential parts of a crane showing an over-hoisting detection device according to a conventional example, where FIG. 1A shows the device in normal operation and FIG. 1B shows the device in over-hoisting operation. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not limiting. Furthermore, shapes and the like in the drawings may be partially exaggerated for the sake of explanation. Furthermore, in the drawings, for ease of viewing, reference symbols may be assigned only to some of the parts that exist with the same attribute.

[0012] [crane] FIG. 1 is an overall view of a crane 1 to which an over-hoisting detection device 100 according to an embodiment of the present invention is applied.

[0013] As shown in Figure 1, the crane 1 of this embodiment is an example of a crane to which the over-hoisting detection device 100 is applied, and is a fixed tower crane installed at a building construction site or the like. The crane 1 includes a mast 4 fixed to a foundation 3 and extending in the vertical direction, a rotating body 5 supported rotatably on the upper part of the mast 4, a jib 6 supported on the rotating body 5 so that it can be raised and lowered, and a load support part 2 suspended from the tip of the jib 6. The mast 4 may also be fixed to the building.

[0014] The rotating body 5 is rotatably supported on the upper part of the mast 4 via a rotating device (not shown). The rotating body 5 is rotatable about an axis extending in the vertical direction. The rotating body 5 may also be supported on the mast 4 so as to be movable up and down in the vertical direction.

[0015] The rotating body 5 is provided with a hoisting winch 8 that enables the jib 6 to be raised and lowered, a lifting winch 9 that enables the load support part 2 to be raised and lowered, and a support frame 10 that stands upright from the rotating body 5.

[0016] A hoisting wire 11 is wound around the hoisting winch 8. The hoisting wire 11 extends from the hoisting winch 8 via a support frame 10 to the jib 6 and is connected to the tip of the jib 6. By driving the hoisting winch 8, the hoisting wire 11 is wound up or let out, allowing the jib 6 to be hoisted with the base end side as a fulcrum.

[0017] A hoisting wire 12 is wound around the lifting winch 9. The hoisting wire 12 extends downward from the tip of the jib 6 from the lifting winch 9, via the support frame 10 and the tip of the jib 6. A load support part 2 is connected to the tip of the hoisting wire 12. By driving the lifting winch 9, the hoisting wire 12 is wound up or let out, allowing the load support part 2 to move up and down in the vertical direction. The load support part 2 is not particularly limited as long as it is capable of supporting a load, and may be, for example, a hook block or a bucket.

[0018] [Overwinding detection device] FIG. 2 is a perspective view of the main parts of the crane 1 showing the normal state of the overwinding detection device 100 according to the first embodiment, and FIG. 3 is a perspective view of the main parts of the crane 1 showing the overwinding detection device 100 according to the first embodiment in an overwinding state.

[0019] As shown in Fig. 1, the overwinding detection device 100 is provided at the tip of the jib 6 and detects overwinding of the hoisting wire 12 (excessive rise of the load support part 2). As shown in Figs. 1 to 3, the overwinding detection device 100 includes a weight 110, a weight suspending member 120, and an overwinding detection part 130 (see Fig. 4).

[0020] The weight 110 is a ring-shaped weight member having a hollow portion 111 , and is installed in a state in which the winding wire 12 passes through the hollow portion 111 .

[0021] The weight suspending member 120 extends downward from the tip of the jib 6 and suspends the weight 110 connected to the tip. It is desirable to have a plurality of weight suspending members 120 in order to stably suspend the weight 110. In this embodiment, the weight 110 is suspended by a pair of weight suspending members 120. The weight suspending member 120 may extend diagonally downward from the tip of the jib 6 as shown in FIG. 1, or may extend directly downward from the tip of the jib 6 as shown in FIG. 2.

[0022] 2 and 3, the weight suspending member 120 is configured with a bendable link mechanism L. This link mechanism L normally maintains an extended position due to the weight of the weight 110 (see FIG. 2), but when the hoisting wire 12 is overwound, it changes to a bent position as the load support part 2 pushes up the weight 110 (see FIG. 3).

[0023] With such a weight suspending member 120, the weight suspending member 120 does not sag when over-wound, as would be the case if the weight suspending member 120 were made of wire, thereby preventing problems caused by the weight suspending member 120 sagging.

[0024] 2 and 3, the link mechanism L constituting the weight hanging member 120 includes an upper link 121 and a lower link 122. The lower end of the upper link 121 and the upper end of the lower link 122 are rotatably connected via a pin P1. This forms a bendable and stretchable weight hanging member 120.

[0025] The upper end of the upper link 121 is rotatably connected to the tip of the jib 6 or to the plunger 132 of the over-winding detection unit 130 via pin P2, and the lower end of the lower link 122 is rotatably connected to the weight 110 via pin P3. As a result, the weight lifting member 120 normally extends due to the weight of the weight 110, and when the hoisting wire 12 is over-wound, it bends as the load support unit 2 pushes up the weight 110.

[0026] As shown in FIG. 3, the bending direction of the weight hanging member 120 is set to an outward opening direction (a direction in which the pin P1 moves away from the hoisting wire 12) to avoid interference with the hoisting wire 12 when bent.

[0027] Furthermore, stopper portions 121a, 122a are formed at the lower end of the upper link 121 and the upper end of the lower link 122. These stopper portions abut against each other to define the extended position of the weight suspending member 120 in the normal state and restrict bending of the weight suspending member 120 in the reverse folding direction. The stopper portions 121a, 122a slightly bend the weight suspending member 120 in the outward opening direction even in the extended position, and when the hoisting wire 12 is over-wound, the weight suspending member 120 is bent in the outward opening direction as the load support portion 2 pushes up the weight 110. This allows the weight suspending member 120 to bend smoothly and reliably during over-winding.

[0028] 4A and 4B are diagrams showing the structure of the overwinding detection unit 130, in which (a) shows the overwinding detection unit 130 in normal operation, and (b) shows the overwinding detection unit 130 in overwinding.

[0029] The overwinding detection unit 130 detects the lifting of the weight 110 by the load support unit 2 when the hoisting wire 12 is overwound. The overwinding detection unit 130 shown in FIG. 4 is a plunger-type limit switch, and is installed between one of the weight lifting members 120 and the jib 6. The plunger-type limit switch includes a push switch 131 that is turned ON when pushed, a plunger 132 that pushes in the push switch 131, and a case 133 that houses the push switch 131 and the plunger 132.

[0030] Push switch 131 is maintained in the OFF state by the biasing force of spring 131a, and is switched to the ON state in response to a pushing operation of plunger 132 against the biasing force of spring 131a. Plunger 132 is supported at the bottom end of case 133 so as to be slidable in the vertical direction, and pushes in push switch 131 by the biasing force of spring 132a.

[0031] As shown in Figure 4(a), when the weight 110 is connected to the lower end of the plunger 132 via the weight suspending member 120, the weight of the weight 110 moves the plunger 132 to a lower position, and the push switch 131 turns OFF. Furthermore, when the load support part 2 pushes up the weight 110 due to over-winding of the hoisting wire 12, the weight suspending member 120 bends, as shown in Figure 4(b), and the load of the weight 110 acting on the plunger 132 is released, so that the plunger 132 moves to an upper position due to the biasing force of the spring 132a. This turns ON the push switch 131, making it possible to detect over-winding of the hoisting wire 12.

[0032] [Second Example] Next, an overwinding detection device 100 according to a second embodiment will be described with reference to Figures 5 and 6. However, for configurations common to the above-described embodiment, the same reference numerals as those in the above-described embodiment will be used, and the description of the above-described embodiment may be used.

[0033] FIG. 5 is a perspective view of the main parts of the crane 1 showing the normal state of the overwinding detection device 100 according to the second embodiment, and FIG. 6 is a perspective view of the main parts of the crane 1 showing the overwinding detection device 100 according to the second embodiment in an overwind state.

[0034] 5 and 6, the overwinding detector 100 of the second embodiment differs from the previously described embodiments in that the weight suspending member 120 is configured to include a joint member J and a wire W in addition to a link mechanism L. The link mechanism L has the same configuration as that of the previously described embodiments. The joint member J has a ring shape through which the hoisting wire 12 passes, and is connected to the upper end of the link mechanism L. The wire W is configured with, for example, two wires, and extends downward from the tip of the jib 6 or the plunger 132 of the overwinding detector 130, suspending the link mechanism L and the weight 110 via the joint member J connected to the tip.

[0035] The overwinding detection device 100 of the second embodiment as described above can also provide the same effects as those of the first embodiment. Furthermore, in the second embodiment, the length of the weight suspending member 120 can be easily extended, so that the approach of the load support part 2 to the overwinding area can be detected early.

[0036] Although the embodiments have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of components of the above-described embodiments.

[0037] For example, in the above-described embodiment, a tower crane is used as an example of a crane, but a crawler crane or a crawler crane can also be used. [Explanation of symbols]

[0038] 1 crane 2 Hanging load support part 21 Protrusions 3 Basics 4 Mast 5 Rotating body 6 Jib 8. Drilling winch 9 Lifting winch 10 Support Frame 11. Drilling wire 12 Winding wire 100 Overwinding detection device 110 Weight 111 Hollow part 120 Hanging member for weight 121 Upper Link 121a Stopper part 122 Lower Link 122a Stopper part 130 Overwinding detector 131 Push switch 131a Spring 132 Plunger 132a Spring 133 cases 201 Weight 202 Weight wire 203 Hanging load support section 204 Protrusions L-link mechanism P1~P3 pins W Wire

Claims

1. An overwinding detection device for a hoisting wire that suspends a load via a load support part, a ring-shaped weight through which the winding wire passes; a weight suspending member for suspending the weight; an overwinding detection unit that detects the lifting of the weight by the load support unit when the hoisting wire is overwound, The weight suspending member is configured by a bendable and extendable link mechanism, An overwinding detection device in which the link mechanism normally maintains an extended position due to the weight of the weight, and when the hoisting wire is overwound, changes to a bent position as the weight is pushed up by the load support part.

2. 2. The overwinding detection device according to claim 1, wherein the link mechanism bends slightly in a predetermined direction even in the extended posture, and bends in the predetermined direction as the weight is pushed up by the load support part when the hoisting wire is overwound.

3. The overwinding detector according to claim 1 or 2, wherein the weight suspending member further includes a wire that suspends the weight via the link mechanism.

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