Load detection device

Abstract

Provide a load detection device with a simple structure, good economic efficiency, and capable of enabling a low price. 【Solution means】A main body 1c having a suspension portion 1a on the upper end side and rotatably supporting a pulley 2 in the circumferential direction of a rotation support shaft by the rotation support shaft 1c extending in the horizontal direction while being supported by the suspension portion, a rotation shaft 3 rotatably supported in the circumferential direction with respect to the rotation support shaft, first levers 7a and second levers 7b having their respective base ends fixed to the rotation shaft and extending with equal lengths from the center of the rotation shaft to their respective tips and facing each other in the diametrical direction, a spring body 4 fixed to the main body and exerting an elastic force upward when the tip of the first lever moves downward, a potentiometer main body portion 5a fixed to the main body, and a potentiometer rod 8 protruding downward in the vertical direction, including a potentiometer 5.

Description

Technical Field

[0001] This invention relates to a load detection device for detecting the load of a heavy object, and more particularly to a load detection device that has a simple structure, is economically efficient, and can be provided at a low cost.

Background Art

[0002] The inventor of the present application has proposed a load detection device in which a load detection plate is interposed at a position where a load is applied to a device for handling a heavy object, and the distortion of the load detection plate due to the load is measured to calculate the load from the amount of distortion (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of this invention is to propose a load detection device that has a simple structure, is economically efficient, and can be provided at a low cost.

Means for Solving the Problems

[0005] The present invention can be exemplified as follows. [1] A main body having a suspension portion on the upper end side and being supported in a vertically suspended state by the suspension portion, and a pulley is rotatably supported in the circumferential direction of the rotation support shaft by a rotation support shaft extending in the horizontal direction, and A rotation shaft rotatably supported in the circumferential direction with respect to the rotation support shaft, and a rotation shaft center that is the center of the rotational movement of the rotation shaft in the circumferential direction is eccentric with respect to the rotation support shaft center that is the center of the rotational movement of the rotation support shaft in the circumferential direction, and is in a position orthogonal to the vertical direction. First levers and second levers, each having a base end fixed to the rotation shaft, extending in a diametrically opposed manner with equal lengths from the center of the rotation shaft to their respective tips. A spring body fixedly provided on the main body, wherein when the rotation shaft is supported by the rotary support shaft in an initial state where the pulley does not suspend a heavy object, an upper end of the spring body, i.e., the spring body upper end, abuts against a vertically lower surface of a first lever tip which is a tip of the first lever, and the spring body exerts an elastic force directed upward in the vertical direction when the first lever tip moves downward in the vertical direction. A potentiometer including a potentiometer main body portion fixed to the main body and a potentiometer rod protruding downward in the vertical direction from the potentiometer main body portion, wherein a tip of the potentiometer rod, i.e., a potentiometer rod tip which is a lower end of the potentiometer rod, abuts against a vertically upper surface of a second lever tip which is a tip of the second lever. It is provided with The potentiometer detects the magnitude of a load according to a displacement amount by which the potentiometer rod moves upward in the vertical direction within the potentiometer main body portion. A load detection device.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a load detection device with a simple structure, high economic efficiency, and the ability to be provided at a low cost.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0008] With reference to the accompanying drawings, a load detection device 20 according to an embodiment of the present invention will be described.

[0009] The load detection device 20 includes a main body 1, a rotating shaft 3, a first lever 7a, a second lever 7b, a spring body 4, and a potentiometer 5.

[0010] The main body 1 has a suspension portion 1a on the upper end side, and is vertically suspended and supported by the suspension portion 1a, and a pulley 2 is rotatably supported in the circumferential direction of the rotary support shaft 1c by the rotary support shaft 1c extending in the horizontal direction as shown in FIG. 1. In the example shown in FIG. 1, the pulley 2 is rotatable in the direction indicated by the arrow 100 or the opposite direction about the rotary support shaft 1c.

[0011] The rotating shaft 3 is rotatably supported with respect to the rotary support shaft 1c and rotates in the circumferential direction of the rotary support shaft 1c. In the example shown in FIG. 1, the rotating shaft 3 is rotatably supported with respect to the rotary support shaft 1c and is adapted to rotate in the direction indicated by the arrow 100 or the opposite direction about the rotary support shaft 1c.

[0012] For example, in the illustrated structure, as shown in FIG. 2, the rotary support shaft 1c is rotatably supported with respect to the main body 1 by bearings 9b, 9c, 10b, and 10c. The rotating shaft 3 is rotatably supported with respect to the main body 1 by bearings 9a, 9d, 10a, and 10d.

[0013] The center of rotation of the rotating shaft 3 in the above-described circumferential rotation motion, which is the center of the rotating shaft, is eccentrically located in a direction orthogonal to the vertical direction with respect to the center of the rotary support shaft, which is the center of the circumferential rotation motion of the rotary support shaft 1c.

[0014] That is, as shown in FIGS. 1 and 3, with respect to the position of the center of the rotation support axis, which is the center of the rotational movement in the circumferential direction at the rotation support axis 1c represented by the dashed line C, the position of the center of the rotation axis, which is the center of the rotational movement in the circumferential direction at the rotation axis 3 represented by the dashed line E, is eccentric by the size represented by the symbol e in FIGS. 1 and 3 in a direction orthogonal to the vertical direction.

[0015] The first lever 7a and the second lever 7b have their proximal ends fixed to the rotation axis 3 respectively, and as shown in FIG. 1, they extend while facing each other in the diametrical direction.

[0016] The proximal end of the first lever 7a is fixed to the rotation axis 3 by the knock pin 6a, and the proximal end of the second lever 7b is fixed to the rotation axis 3 by the knock pin 6b.

[0017] The length that the first lever 7a extends from the above-mentioned center of the rotation axis of the rotation axis 3 to the tip of the first lever 7c, which is its tip, is the same as the length that the second lever 7b extends from the above-mentioned center of the rotation axis of the rotation axis 3 to the tip of the second lever 7d, which is its tip.

[0018] The spring body 4 is fixed to the main body 1 of the load detection device 20. And the upper end of the spring body 4, that is, the upper end 4b of the spring body, is in contact with the lower vertical surface of the tip of the first lever 7c when the rotation axis 3 is supported by the rotation support axis 1c in the initial state where the pulley 2 does not suspend a heavy object, as shown in FIG. 1.

[0019] When the tip of the first lever 7c moves downward in the vertical direction as indicated by the arrow 101 in FIG. 1 from this arranged state, the spring body 4 exerts an elastic force upward in the vertical direction.

[0020] The potentiometer 5 includes a potentiometer main body portion 5a and a potentiometer rod 8.

[0021] In the embodiment shown in FIG. 1, the potentiometer main body portion 5a is fixed to the main body 1 of the load detection device 20. Further, the potentiometer rod 8 protrudes downward in the vertical direction from the potentiometer main body portion 5a fixed to the main body 1 in this way.

[0022] And the tip 8a of the potentiometer rod, which is the lower end of the potentiometer rod 8, is in contact with the upper vertical surface of the tip 7d of the second lever.

[0023] The potentiometer 5 detects the magnitude of the load according to the amount of displacement in which the potentiometer rod 8 moves upward in the vertical direction within the potentiometer main body portion 5a.

[0024] As described above, since the length that the first lever 7a extends from the center of the rotation axis of the rotation axis 3 to the tip 7c of the first lever and the length that the second lever 7b extends from the center of the rotation axis of the rotation axis 3 to the tip 7d of the second lever are the same, the length L from the above-described center of the rotation axis of the rotation axis 3 to the center of the spring in the vertical direction in the spring body 4 and the length L from the above-described center of the rotation axis of the rotation axis 3 to the position where the tip 8a of the potentiometer rod 8 in the potentiometer 5 is in contact with the upper vertical surface of the tip 7d of the second lever are the same (FIGS. 1 and 3).

[0025] As shown in FIGS. 1 and 2, when a load indicated by the symbol W (FIG. 2) is applied to the load detection device 20 by suspending a heavy object from the rope 11 suspended by the pulley 2, a load indicated by the symbol W1 is applied to the rope portion 11a on one side of the rope 11, and a load indicated by the symbol W2 is applied to the rope portion 11b on the other side of the rope 11 (FIG. 1).

[0026] In the load detection device 20 of the present embodiment, the pulley 2 that suspends the rope 11 is rotatably supported in the circumferential direction of the rotation support shaft 1c by the rotation support shaft 1c horizontally supported by the main body 1 of the load detection device 20.

[0027] Further, the rotation shaft 3 to which the proximal ends of the first lever 7a and the second lever 7b are fixed is supported so as to be rotatable in the circumferential direction of the rotation support shaft 1c with respect to the rotation support shaft 1c.

[0028] When a load indicated by reference sign W (FIG. 2) is applied to the load detection device 20, and loads indicated by reference signs W1 and W2 are applied to the rope portion 11a, which is one side of the rope 11, and the rope portion 11b, respectively, the rotation support shaft 1c moves downward in the vertical direction.

[0029] Here, the rotation shaft 3 is supported so as to be rotatable in the circumferential direction with respect to the rotation support shaft 1c. The rotation shaft center, which is the center of the rotational movement of the rotation shaft 3 in the above-described circumferential direction, is at a large and eccentric position represented by reference sign e in FIGS. 1 and 3 in a direction orthogonal to the vertical direction with respect to the rotation support shaft center, which is the center of the rotational movement of the rotation support shaft 1c in the above-described circumferential direction.

[0030] Therefore, when a vertically downward load W (FIG. 2) is applied to the pulley 2 and the rotation support shaft 1c moves downward in the vertical direction, the rotation shaft, which is rotatably supported by the rotation support shaft 1c and has a rotation shaft center at a large and eccentric position represented by reference sign e in FIGS. 1 and 3 in a direction orthogonal to the vertical direction with respect to the rotation support shaft center of the rotation support shaft 1c, rotates in the direction indicated by arrow 100 in FIG. 1 according to the amount of eccentricity.

[0031] Accordingly, the first lever 7a and the second lever 7b also rotate together with the rotation shaft 3 in the direction indicated by arrow 100 in FIGS. 1 and 3 about the rotation support shaft 1c.

[0032] Therefore, the tip 7c of the first lever moves downward in the vertical direction as indicated by arrow 101 in FIG. 1, and the tip 7d of the second lever moves upward in the vertical direction as indicated by arrow 102 in FIG. 1.

[0033] As the tip 7d of the second lever moves upward in the vertical direction as indicated by the arrow 102 in Fig. 1, the potentiometer rod 8 with the tip 8a of the potentiometer rod in contact with the upper surface in the vertical direction of the tip 7d of the second lever moves upward in the vertical direction within the potentiometer main body 5a.

[0034] According to the amount of displacement of this movement, the potentiometer 5 will detect the magnitude of the load.

[0035] At this time, with respect to the downward movement in the vertical direction of the tip 7c of the first lever as indicated by the arrow 101 in Fig. 1, since the spring body 4 exerts an elastic force upward in the vertical direction, the upward movement in the vertical direction of the potentiometer rod 8 within the potentiometer main body 5a will be gentle.

[0036] The potentiometer 5 can detect the magnitude of the load W according to the amount of displacement in which the potentiometer rod 8 moves upward in the vertical direction within the potentiometer main body 5a, based on preset conditions such as the eccentricity represented by the symbol e in Figs. 1 and 3 described above.

[0037] In the load detection device 20 of this embodiment, the pulley 2 suspending the rope 11 is rotatably supported in the circumferential direction of the rotary support shaft 1c by the rotary support shaft 1c horizontally supported by the main body 1 of the load detection device 20.

[0038] Also, the rotation shaft 3 to which the proximal ends of the first lever 7a and the second lever 7b are fixed is rotatably supported with respect to the rotary support shaft 1c and rotates in the circumferential direction of the rotary support shaft 1c.

[0039] And the center of rotation of the rotation shaft 3, which is the center of the rotational movement in the above-described circumferential direction, is at a large and eccentric position in a direction orthogonal to the vertical direction with respect to the center of the rotary support shaft, which is the center of the rotational movement in the above-described circumferential direction of the rotary support shaft 1c, and is represented by the symbol e in Figs. 1 and 3.

[0040] As a result, even when the load W is large, it becomes possible to detect it as a very small load.

[0041] For example, when the load applied to the pulley 2 is 2800 kg (that is, the load W1 applied to the rope portion 11a = 1400 kg, the load W2 applied to the rope portion 11b = 1400 kg), at this time, when the rotation support shaft 1c moves 10 mm downward in the vertical direction, let the magnitude of the load detected by the potentiometer 5 be P, the length L from the center of the rotation axis of the rotation shaft 3 to the spring center extending in the vertical direction in the spring body 4 = 65 mm, and the eccentricity represented by the symbol e in FIGS. 1 and 3 = 2 mm. Then, P is derived by the following calculation formula.

[0042] P = 2 (two ropes) × 1400 kg × {2 mm (eccentricity) / 65 mm (magnitude of L)} = 86.1538 kg Therefore, even when a load of 2800 kg is applied to the pulley 2, if the potentiometer 5 capable of detecting 86.1538 kg is provided, the load can be easily detected.

[0043] Therefore, it is possible to provide a load detection device that has a simple structure compared to the case where a small compression type load cell is provided at the location where the spring body 4 is provided in the above-described embodiment, and that can be provided economically and at a low price.

[0044] In addition, considering that it is within an allowable error of 3% for a crane lifting a heavy object, it is desirable that the eccentricity represented by the symbol e in FIGS. 1 and 3 described above is 2 mm or less.

[0045] As described above, the embodiments of the present invention have been described with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the technical scope grasped from the description of the claims for utility model registration.

Claims

[Claim 1] a main body having a hanging part at an upper end side, and supporting the pulley by a horizontally extending rotary support shaft in a state where the pulley is suspended and supported in a vertical direction by the hanging part, so that the pulley can be freely rotated in a circumferential direction of the rotary support shaft; a rotation shaft supported rotatably in the circumferential direction with respect to the rotation support shaft, wherein a rotation shaft center, which is a center of rotational motion of the rotation shaft in the circumferential direction, is eccentric in a direction perpendicular to the vertical direction with respect to a rotation support shaft center, which is a center of rotational motion of the rotation support shaft in the circumferential direction; a first lever and a second lever, each of whose base ends is fixed to the rotating shaft, and which extend from the center of the rotating shaft to their respective tips with equal lengths and in opposing relation to each other in a diametrical direction; a spring body fixed to the main body, the upper end of which abuts against a vertically lower surface of a tip of the first lever, which is a tip of the first lever when the rotating shaft is supported by the rotating support shaft in an initial state in which the pulley does not suspend a weight, and the spring body exerts an elastic force moving vertically upward when the tip of the first lever moves vertically downward; a potentiometer including a potentiometer body portion fixed to the main body, and a potentiometer rod protruding downward in a vertical direction from the potentiometer body portion, the potentiometer rod tip portion being a lower end of the potentiometer rod abutting against a vertically upper side surface of a second lever tip portion being a tip of the second lever; Equipped with The potentiometer detects the magnitude of the load according to the amount of displacement of the potentiometer rod moving vertically upward within the potentiometer body. Load detection device.

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