Load detection device

Abstract

To solve the problem that a conventional load detection device may tend to be heavy.SOLUTION: According to the present invention, there is provided a load detection device including: a first member located on a boom side of a high-lift work vehicle; a second member located on a work platform side of the high-lift work vehicle; a load receiving member; a load detection unit; and a parallel link including an upper link and a lower link; wherein the second member is connected to the first member by the parallel link so as to be movable in a vertical direction; wherein the first member includes two first side plates and a mounting table connected and fixed between the first side plates; wherein the second member includes two second side plates and a load piece connected and fixed between the two second side plates; wherein the load receiving member is located from between the two first side plates to between the two second side plates and receives a load between the mounting table and the load piece; and wherein the first side plates and the second side plates do not overlap each other when viewed from a side.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a load detection device for detecting the load on a work platform in an aerial work vehicle configured by attaching a work platform to the tip of a boom provided on a vehicle body. [Background technology]

[0002] Aerial work platforms are equipped with a swivel platform on the vehicle, a boom that rises and falls from the swivel platform, and a work platform at the end of the boom. The work platform can be moved to a desired location at high altitudes by rotating the swivel platform, changing the boom's elevation angle, and extending and retracting the boom. The work platform carries workers, tools, materials, etc., but the load capacity of the work platform is limited for safety reasons. In the aerial work platform of Patent Document 1, the work platform is attached via a parallel link mechanism, and a spring member contracts in response to the load on the work platform. The downward displacement of the work platform resulting from the contraction of the spring member is transmitted via a transmission mechanism. An overloaded work platform is detected by the output signal of a displacement signal output device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-118354 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional load detection devices, the spring is located where the boom member and the platform member overlap laterally, so if the spring radius is increased or the strength of the load detection device is increased in line with the size of the platform, the load detection device may become heavy. [Means for solving the problem]

[0005] (1) One embodiment of the present invention is a load detection device comprising a first member located on the boom side of the aerial work vehicle, a second member located on the work platform side of the aerial work vehicle, a load-receiving member, a load detection unit, and a parallel link consisting of an upper link and a lower link, wherein the second member is connected to the first member by the parallel link so as to be movable in the vertical direction, the first member has two first side panels and a mounting base connected and fixed between the first side panels, the second member has two second side panels and a load piece connected and fixed between the two second side panels, the load-receiving member is located between the two first side panels and between the two second side panels, and receives a load between the mounting base and the load piece, and the first side panel and the second side panel do not overlap when viewed from the side.

[0006] (2) One embodiment of the present invention is a load detection device as described in (1), characterized in that the gap distance between the first side panel and the second side panel, as viewed from the side, changes depending on the load condition, and the gap is maintained by a stopper even when the load exceeds an overload or when vertical vibrations occur during driving, etc.

[0007] (3) One embodiment of the present invention is the load detection device according to (2), characterized in that the first side plate and the second side plate are provided on the same plane.

[0008] (4) One embodiment of the present invention is the load detection device of (1), characterized in that the load receiving member is located between the center of the upper link and the center of the lower link.

[0009] (5) One embodiment of the present invention is a load detection device of (1), characterized in that, when no load is applied, the vertical center axis of the load-receiving member is positioned near the gap between the first side panel and the second side panel when viewed from the side.

[0010] (6) One embodiment of the present invention is a load detection device according to (1), characterized in that the first side panel has an approximately inverted triangular shape, a boom mounting hole is provided at the top of the first member, a level link mounting hole is provided at a position diagonally below the boom mounting hole, and the load-receiving member is provided on the side of the second member relative to the leveling link mounting hole.

[0011] (7) One embodiment of the present invention is a load detection device according to (6), characterized in that the mounting base and the load piece are formed by L-shaped plates, the mounting base has a first connecting vertical plate extending vertically, a first connecting horizontal plate extending horizontally connected to the first connecting vertical plate, and a first protruding horizontal plate extending from the first connecting horizontal plate, the first connecting vertical plate and the first connecting horizontal plate being fixed to the first side plate, the first protruding horizontal plate protruding from the first member toward the second member, the load piece has a second connecting vertical plate extending vertically, a second connecting horizontal plate extending horizontally connected to the second connecting vertical plate, and a second protruding horizontal plate extending from the second connecting horizontal plate, the second connecting vertical plate and the second connecting horizontal plate being fixed to the second side plate, and the second protruding horizontal plate protruding from the second member toward the first member.

[0012] Furthermore, the present invention also includes the following embodiments.

[0013] (8) One embodiment of the present invention is a load detection device (7) characterized in that the mounting base is such that the first connecting vertical plate is positioned below the first connecting horizontal plate and reaches the side of the lower link.

[0014] (9) One embodiment of the present invention is a load detection device (7) characterized in that the load piece is positioned above the second connecting vertical plate and the second connecting horizontal plate, reaching the side of the upper link.

[0015] (10) One embodiment of the present invention is the load detection device of (7), wherein the second connecting vertical plate of the load piece is located on the side of the workbench mounting portion.

[0016] (11) One embodiment of the present invention is a load detection device according to any one of (1) to (10), characterized in that the load detection unit has a switch, the load receiving member has a spring adjusted so as not to contract until a predetermined load is reached, and the contraction of the spring causes the second member to descend relative to the first member, activating the switch to detect an overload.

[0017] (12) One embodiment of the present invention is a load detection device (11) characterized in that the first member is a load detection device in which two of the first side plates are connected by a first connecting plate, and the switch is located above the first side plates.

[0018] (13) One embodiment of the present invention is the load detection device according to any one of (1) to (10), characterized in that the load detection unit includes a load cell, and an overload is detected by the load cell.

[0019] (14) One embodiment of the present invention is a load detection device according to any one of (1) to (10), characterized in that a first stopper portion is provided on the first member, a second stopper portion is provided on the second member, and the first stopper portion and the second stopper portion located below the first stopper portion restrict upward movement of the second member relative to the first member.

[0020] (15) One embodiment of the present invention is a load detection device (14) characterized in that a lower stopper receiver is provided at the lower part of the first member, a lower stopper portion is provided at the lower part of the second member, and the lower stopper receiver and the lower stopper portion located above the lower stopper receiver restrict downward movement of the second member relative to the first member. [Effects of the Invention]

[0021] In one embodiment of the present invention, a relatively lightweight and strong load detection device can be realized. [Brief explanation of the drawings]

[0022] [Figure 1]FIG. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 2 is a diagram showing the internal structure of the load detection device. DETAILED DESCRIPTION OF THE INVENTION

[0023] FIG. 1 shows a vehicle for aerial work 1 during operation. The vehicle for aerial work 1 has a swivel 12 mounted on a vehicle 11. During operation, a boom 13 is raised from the swivel 12, and a work platform 14, located near the tip of the boom 13, is lifted to a high place. The boom 13 in FIG. 1 has an upper boom 132 connected to the top of a lower boom 131 raised from the swivel 12, and the work platform 14 is connected to the tip of the upper boom 132 via a load detection device 2. The lower boom 131 and the upper boom 132 are telescopic booms, and can be extended to a longer position than in the state shown in FIG. 1. When working with the vehicle for aerial work 1, the vehicle for aerial work 1 is lifted by outriggers 15 attached to the vehicle 11, as shown in FIG. 1, to stabilize the vehicle for aerial work 1.

[0024] In FIG. 1, the load detection device 2 is provided between the boom 13 and the work platform 14. FIG. 2 shows an enlarged side view of the load detection device 2, and FIG. 3 shows a top view. The load detection device 2 of this embodiment includes a first member 21, a second member 22, a load-receiving member 23, a parallel link 24, and a load detection unit 26. The load-receiving member 23 and the parallel link 24 are located inside the first member 21 and the second member 22. The first member 21 has a structure in which a first connecting plate 213 and the like are connected between two first side plates 211. The first member 21 shown in FIG. 2 is attached to the boom 13 shown in FIG. 1 on the right side. The second member 22 has a structure in which a second connecting plate 225 and the like are connected between two second side plates 221. The work platform 14 is attached to the left side of the second member 22 shown in FIG. 2. 2 and 3, the load-receiving member 23 and the parallel link 24 are almost hidden inside the first member 21 and the second member 22. The parallel link 24 is attached to the first member 21 and the second member 22 by a link pin 25. The load detection unit 26 is provided on the upper part of the load detection device 2. In this embodiment, the two first side plates 211 and the first connecting plate 213 between them are fixed by welding. The same is true for the two second side plates 221 and the second connecting plate 225.

[0025] The first member 21 has two first side panels 211, each of which has a leveling link mounting hole 211a and two upper and lower link mounting holes 211b. The periphery of these mounting holes is thickened by bosses. As shown in FIG. 2, the outer periphery of a boom mounting boss 216 is fixed to a hole in the first side panel 211, and the inside of the boom mounting boss 216 forms a boom mounting hole 216a. The tip of the boom 13 shown in FIG. 1 is rotatably mounted to the boom mounting hole 216a with a pin (not shown). Furthermore, a leveling link (not shown) provided at the tip of the boom 13 is mounted to the leveling link mounting hole 211a via a leveling link mounting pin (not shown). The angle of the first member 21 relative to the boom 13 is changed by the movement of the leveling link relative to the boom mounting hole 216a. This allows the work platform 14 to be kept horizontal when the rising angle of the boom 13 changes.

[0026] As shown in Figure 3, when the second member 22 is combined with the first member 21 by the parallel link 24, the second side panel 221 of the second member 22 is located on the same plane as the first side panel 211 of the first member 21 and does not overlap when viewed from the side.

[0027] 2 and 3, the link pin 25 provided on the first member 21 is inserted through the link mounting hole 211b of the first side plate 211, the parallel link 24, and the link mounting hole 211b of the other first side plate 211. In addition, the link pin 25 provided on the second member 22 is inserted through the link mounting hole 221a of the second side plate 221, the parallel link 24, and the link mounting hole 221a of the other second side plate 221. There is a gap between the first side plate 211 and the second side plate 221, and the parallel link 24 and the link pin 25 allow the second member 22 to move up and down relative to the first member 21 while maintaining its up and down orientation.

[0028] 2, a first stopper portion 212 is provided by a recess 211d at the end of the first side panel 211 close to the second side panel 221, and a lower stopper receiver 215 is provided on the underside of the first side panel 211. The first stopper portion 212 has a surface facing downward of the first side panel 211 in the recess 211d, and is opposed to and slightly spaced from a surface of the second stopper portion 222 facing upward of the second side panel 221.

[0029] The second member 22 is provided with a workbench mounting portion 223 and an angle change bar 224. As shown in FIG. 3, a shaft hole 223a is provided in the center of the workbench mounting portion 223. The angle change bar 224 is fixed so as to protrude obliquely from the workbench mounting portion 223 with respect to a line connecting the center of the shaft hole 223a and the center of the first member 21, as shown by the dotted line in FIG. 3. Workbench members (not shown) are disposed above and below the workbench mounting portion 223 shown in FIG. 2, and the second member 22 rotatably holds the workbench 14 by passing a shaft (not shown) from the workbench member through the shaft hole 223a. Then, by pushing or pulling the tip of the angle change bar 224 from the side of the workbench 14 using a cylinder (not shown), the workbench 14 can be moved left and right in FIG. 3, and the workbench 14 can be rotated sideways as if swinging its head.

[0030] 2, a second stopper portion 222 is provided by a protrusion 221c on the side of the second side panel 221 facing the first side panel 211, and a lower stopper portion 228 is provided on the lower side. In FIG. 2, most of the lower stopper portion 228 is located on the back side of the first side panel 211, and a portion of it is visible in the gap between the first side panel 211 and the second side panel 221. The second stopper portion 222 has a surface facing upward toward the second side panel 221 by the protrusion 221c, and faces the surface of the first stopper portion 212 facing downward toward the first side panel 211.

[0031] If the second member 22 attempts to rise excessively relative to the first member 21, the first stopper portion 212 and the second stopper portion 222 come into contact with each other, stopping the ascent. If the second member 22 attempts to fall excessively relative to the first member 21, the lower stopper portion 228 comes into contact with the lower stopper receiver 215, stopping the descent. The first stopper portion 212, the second stopper portion 222, the lower stopper receiver 215, and the lower stopper portion 228 form a stopper. The detailed positions and shapes of the lower stopper receiver 215 and the lower stopper portion 228 will be described later with reference to perspective views in Figures 4 and 5.

[0032] As shown in FIG. 3, the first side panel 211 and the second side panel 221 are provided on the same plane. Also, as shown in FIG. 2, the first side panel 211 and the second side panel 221 do not overlap when viewed from the side, and as shown in FIGS. 2 and 3, there is a gap between the first side panel 211 and the second side panel 221. The width of this gap changes when a load is applied to the second member 22 to which the workbench 14 is connected, and the gap narrows under a heavy load. However, the lower stopper portion 228 abuts against the lower stopper receiver 215, eliminating this gap and preventing contact. The lower stopper receiver 215 of the first member 21 and the lower stopper portion 228 of the second member 22 regulate the second member 22 so that it does not descend relative to the first member 21 beyond the allowable stroke (the range in which the switch will not be damaged) when an overload occurs.

[0033] Furthermore, if the second member 22 attempts to rise excessively relative to the first member 21, the first stopper portion 212 and the second stopper portion 222 shown in FIG. 2 come into contact with each other to stop the rise, and as a result, the horizontal gap in FIG. 2 is maintained even when the second member 22 attempts to rise excessively. As described above, the stoppers ensure a gap between the first side plate 211 and the second side plate 221 in the left-right direction in FIG. 2, which prevents the first side plate 211 and the second side plate 221 from coming into contact with each other during up-and-down vibration or overload, thereby preventing excessive force from acting on the parallel link 24 or the link pin 25. Note that under normal circumstances, the first stopper portion 212 and the second stopper portion 222 are spaced apart, and do not adhere to each other even if water, oil, or the like gets on them.

[0034] As shown in Fig. 2, the first member 21 has link mounting holes 211b at the top and bottom of the first side panel 211, close to the second member 22, and the second member 22 has link mounting holes 221a at the top and bottom of the second side panel 221, close to the first member 21. The periphery of these link mounting holes is formed thick. Parallel links 24, provided on the inside of the first side panel 211 and the second side panel 221, are rotatably fixed by link pins 25 fitted into the link mounting holes 211b and 221a. In Fig. 2, most of the parallel links 24 are located behind the first side panel 211 and the second side panel 221, and a portion of them is visible in the gap between the first side panel 211 and the second side panel 221.

[0035] As shown in Fig. 3, a recess 213a is formed on the side of first connecting plate 213 located at the top of first member 21, closer to second connecting plate 225. A protrusion 225a is formed on the side of second connecting plate 225 located at the top of second member 22, closer to first connecting plate 213, and this protrusion 225a fits into the recess 213a of first connecting plate 213. A portion of second connecting plate 225 fits between the two first side plates 211, from which a detection unit fixing plate 227 protrudes upward. The recess 213a and protrusion 225a are also shown in Figs. 4 and 5, which will be described later.

[0036] 2 and 3, at the top of the load detection device 2, the load detection unit 26 is attached to the protrusion 225a of the second connection plate 225 and the detection unit fixing plate 227. The load detection unit 26 has a switch 261, a switch mounting piece 262, a horizontal bolt 263, a horizontal nut 264, a vertical bolt 265, a vertical nut 266, and a fixing screw 267. The switch mounting piece 262 is attached to the protrusion 225a of the second connection plate 225 by the vertical bolt 265 and the vertical nut 266, and is attached to the detection unit fixing plate 227 by the horizontal bolt 263 and the horizontal nut 264. In FIG. 2, the switch 261 is located on the back side of the switch mounting piece 262 and is fixed to the switch mounting piece 262 by fixing screws 267 at two locations.

[0037] The switch 261 of the load detection unit 26, which is attached to the detection unit fixing plate 227 fixed to the second connection plate 225, is located above the first connection plate 213. Therefore, when the second connection plate 225 moves down relative to the first connection plate 213, the switch 261 moves down and a switch button 261a (see FIG. 8), which will be described later, is pressed by the first connection plate 213. Pressing the switch button 261a activates the switch 261. The detection unit fixing plate 227 supports the switch mounting piece 262 so that it does not tilt even when the switch button 261a is pressed.

[0038] 4 is a perspective view of the first member 21. A first connecting plate 213 connects the two first side plates 211 at the upper part. Slightly below the first connecting plate 213, the two first side plates 211 are connected by a boom mounting boss 216. Slightly below the middle in the vertical direction, the two first side plates 211 are connected by a mounting base 214. Furthermore, at the lowest part, the two first side plates 211 are connected by a lower stopper receiver 215.

[0039] In the mounting base 214, a first connecting horizontal plate 214a and a first connecting vertical plate 214b (described later) are connected to the two first side plates 211 between the two first side plates 211. A first protruding horizontal plate 214c extending from the first connecting horizontal plate 214a protrudes from between the two first side plates 211 toward the second member 22. The first side plate 211 is fixed to the first connecting plate 213, the mounting base 214, etc. by welding. The same is true for the first side plate 211 and the lower stopper receiver 215.

[0040] The mounting base 214 is provided with an adjustment screw hole 214d extending from the first connecting horizontal plate 214a to the first protruding horizontal plate 214c, and a plurality of mounting holes 214e are provided in the first connecting horizontal plate 214a and the first protruding horizontal plate 214c.

[0041] 4, the outer peripheral surface of the boom mounting boss 216 is fixed in a hole formed in the first side panel 211. A reinforcing plate 217 is provided in the vertical direction at the bottom of the first member 21, protruding outward from a portion of the first side panel 211 that is close to the second member 22 during assembly. The reinforcing plate 217 is provided on the outside of the portion of the first side panel 211 that is connected to the first connecting horizontal panel 214a on the inside.

[0042] 2 and 4, the first side panel 211 has a generally inverted triangular shape with a narrower width at the bottom. Each of the two first side panels 211 is provided with a leveling link mounting hole 211a and two upper and lower link mounting holes 211b. A boom mounting hole 216a is provided at the top of the first member 21, and a leveling link mounting hole 211a is provided diagonally below the boom mounting hole 216a.

[0043] Furthermore, a recess 211d is provided between the first opposing surfaces 211c that are provided on the same plane in the two first side plates 211 of the first member 21 in a portion that is close to the second member 22 when the load detection device 2 is assembled. The recess 211d is provided between the upper link mounting hole 211b and the first connecting horizontal plate 214a in the up-down direction, and a first stopper portion 212 is provided above the recess 211d. The lower surface of the first stopper portion 212 is a flat surface that is provided in a direction perpendicular to the first opposing surface 211c. Furthermore, a lower stopper receiver 215 is connected to the lower portions of the two first side plates 211. The vertical positional relationship of the first member 21 is, from top to bottom, the first connecting plate 213, the upper link mounting hole 211b, the first stopper portion 212, the recess 211d, the first connecting horizontal plate 214a and the first protruding horizontal plate 214c, the lower link mounting hole 211b, and the lower stopper receiver 215.

[0044] 5 is a perspective view of the second member 22. A second connecting plate 225 connects the two second side panels 221 at the top and bottom. A load piece 226 connects the two second side panels 221 slightly above the middle in the vertical direction. The two second side panels 221 are also connected at the workbench mounting portion 223.

[0045] The load piece 226 rises from the second connecting horizontal plate 226a to form a second connecting vertical plate 226b (described later), and extends in the opposite direction from the second connecting horizontal plate 226a to form a second protruding horizontal plate 226c. In the load piece 226, the second connecting horizontal plate 226a and the second connecting vertical plate 226b are connected to the two second side plates 221 between the two second side plates 221. The second protruding horizontal plate 226c extending from the second connecting horizontal plate 226a protrudes from between the two second side plates 221 toward the first member 21. The second side plates 221 are fixed to the upper and lower second connecting plates 225 and the load piece 226 by welding.

[0046] In the second member 22 shown in FIG. 5, each of the two second side plates 221 has two link mounting holes 221a, one above the other, and each second side plate 221 has a second stopper portion 222. The second stopper portion 222 is provided on a protrusion 221c where the second side plate 221 protrudes toward the first member 21. In addition, a lower stopper portion 228 is provided below the second connecting plate 225 on the lower part of the second member 22 so as to protrude toward the first member 21. The connection between the second connecting plate 225 and the lower stopper portion 228 is also fixed by welding. When the second member 22 is lowered significantly, the lower stopper portion 228 is stopped by a stopper receiver 215 of the first member 21. Multiple thin plates (not shown) are placed and fixed on the lower stopper receiver 215, and the lower stopper portion 228 comes into contact with the thin plates and stops. By changing the number of thin plates or the like and adjusting their thickness, the stopping position of the lower stopper portion 228 relative to the lower stopper receiver 215 can be adjusted, and the maximum lowering position of the second member 22 relative to the first member 21 can be adjusted.

[0047] A workbench mounting part 223 having a vertical shaft hole 223a is fixed to the two second side panels 221 and the upper and lower second connecting plates 225 on the opposite side to the second protruding horizontal panel 226c. Furthermore, angle changing bars 224 are attached to the upper and lower sides of the workbench mounting part 223 on the opposite side to the second protruding horizontal panel 226c. The workbench mounting part 223 and the angle changing bar 224 are located at the top of the second member 22. The connections between the workbench mounting part 223, the second side panels 221, the second connecting plates 225, and the angle changing bars 224 are also fixed by welding.

[0048] As shown in FIG. 5, the load detection unit 26 is provided on the upper part of the second member 22. A switch 261 of the load detection unit 26 is attached to an L-shaped switch mounting piece 262 with two fixing screws 267. The switch mounting piece 262 is attached to a convex portion 225a, which is a protruding portion of the second connecting plate 225, with a vertical bolt 265 and two vertical nuts 266 so that its height can be adjusted. As shown in FIG. 2, the switch 261 is located on the upper part of the first connecting plate 213 of the first member 21, and moves up and down together with the second member 22. When the second member 22 descends relative to the first member 21, the lower part of the switch 261 abuts against the first connecting plate 213, and a counterclockwise rotational force acts on the switch mounting piece 262 around the vicinity of the vertical bolt 265. 2 and 5, to prevent the position of the switch 261 from shifting due to this left rotational force, the switch mounting piece 262 is fixed by a horizontal bolt 263 to an L-shaped detection unit fixing plate 227 extending vertically from the second connecting plate 225. A fixing hole (not shown) provided in the switch mounting piece 262 through which the horizontal bolt 263 passes is formed vertically, allowing the switch mounting piece 262 to move up and down when adjusting the height with a vertical bolt 265 and a vertical nut 266.

[0049] 6 is a perspective view of the load-receiving member 23. The load-receiving member 23 has a base 231, a cylindrical cover tube 232 fixed on the base 231, a spring 233 housed in the cover tube 232, and a spring upper surface plate 234 that presses the top of the spring 233. It also has an adjustment bolt 235 that passes through the center of the spring upper surface plate 234, the spring 233, and the base 231, and two adjustment nuts 236 that lock the adjustment bolt 235 below the base 231.

[0050] The base 231 of the load-receiving member 23 is fixed to the mounting base 214 of the first member 21 shown in FIG. 4 with a mounting screw 237, which will be described later. The adjustment bolt 235 shown in FIG. 6 is inserted downward from above the spring upper plate 234, passes through the spring 233, and protrudes below the base 231. The adjustment bolt 235 then engages with an adjustment nut 236 below the base 231. The base 231 acts as a stopper to prevent the adjustment nut 236 from entering the cover tube 232. Two adjustment nuts 236 are used, so the adjustment bolt 235 is securely fixed. When the load-receiving member 23 is attached to the mounting base 214, the lower end of the adjustment bolt 235 and the adjustment nut 236 protrude below the adjustment screw hole 214d in the mounting base 214 shown in FIG. 4.

[0051] The adjustment bolt 235 in Figure 6 pushes the spring upper plate 234 downward depending on the tightening position of the adjustment nut 236, compressing the spring 233 and adjusting the length and upward force of the spring 233. The spring 233 is longer than the cover tube 232, and as shown in Figure 6, there is a gap between the spring upper plate 234 and the cover tube 232. When a load above a certain value is applied to the spring upper plate 234, the position of the spring upper plate 234 drops, the spring 233 compresses, and this gap narrows. Furthermore, the top of the spring upper plate 234 has a recess in the center so that the head of the adjustment bolt 235 does not hit the spring upper plate 234 when it receives a load due to the configuration of the second member 22.

[0052] FIG. 7 shows the parallel link 24. The parallel link 24 is composed of an upper link 241 on the upper side and a lower link 242 on the lower side. The upper link 241 has an H-shaped link body 241a connecting two side plates at the center, and two link shafts 241b connecting the two side plates of the link body 241a at both ends. The lower link 242 similarly has a link body 242a and a link shaft 242b. A link pin 25 is inserted into the link shaft 242b, and the upper upper link 241 and the lower lower link 242 are rotatably fixed between the first side plate 211. Similarly, the upper link 241 and the lower link 242 are rotatably fixed between the second side plate 221. The second member 22 is connected by the parallel link 24 so as to be movable in the vertical direction when viewed from the first member 21. During the movement, the second member 22 does not rotate relative to the first member 21, and the up-and-down direction of the second member 22 is maintained.

[0053] FIG. 8 shows the internal structure of the load detection device 2. FIG. 8 shows the center of the side of the load detection device 2 with the first side panel 211 and the second side panel 221 on the near side removed. The first member 21 is on the right and the second member 22 is on the left. In FIG. 8, both ends of the load detection device 2 are omitted. The diagonal lines indicate the connection between the removed first side panel 211 and the second side panel 221, and a cross section of the link pin 25 at the same plane as the connection between the removed first side panel 211 and the second side panel 221. The link pin 25 is inserted into the upper link 241 and the lower link 242. The parallel link 24 formed by the upper link 241 and the lower link 242 is located from the first member 21 to the second member 22, linking the first member 21 and the second member 22 in parallel.

[0054] 8, the mounting base 214 of the first member 21 has a first connecting vertical plate 214b extending vertically, a first connecting horizontal plate 214a connected to the first connecting vertical plate 214b and extending horizontally, and a first protruding horizontal plate 214c extending horizontally from the first connecting horizontal plate 214a, and is formed into an L-shaped plate. The mounting base 214 has a structure in which a thick plate forming the first protruding horizontal plate 214c, first connecting horizontal plate 214a, and first connecting vertical plate 214b is bent at a right angle between the first connecting horizontal plate 214a and the first connecting vertical plate 214b. Both sides of the first connecting horizontal plate 214a and the first connecting vertical plate 214b are fixed to the first side panel 211 by welding. On the other hand, the first protruding horizontal plate 214c is not directly fixed to the first side panel 211, but is fixed to the first side panel 211 via a first connecting horizontal plate 214a and a first connecting vertical plate 214b. The first protruding horizontal plate 214c protrudes from the first member 21 toward the second member 22.

[0055] The mounting base 214 has the first connecting vertical plate 214b positioned below the first connecting horizontal plate 214a and reaching the side of the lower link 242. Therefore, the mounting base 214 firmly connects the two first side plates 211 in the vicinity of the link mounting hole 211b shown in Figures 2 and 4, where the lower link 242 is attached and where force acts.

[0056] 8, the mounting base 214 has a first connecting horizontal plate 214a extending in the horizontal direction, indicated by diagonal lines, and a first connecting vertical plate 214b bending and extending downward from the first connecting horizontal plate 214a, which are fixed to the first side plate 211 between the two first side plates 211. On the other hand, a first protruding horizontal plate 214c extending in the horizontal direction from the first connecting horizontal plate 214a into the second member 22 on the opposite side of the first connecting vertical plate 214b is not fixed to the first side plate 211. However, because the mounting base 214 is fixed to the first side plate 211 not only by the first connecting horizontal plate 214a but also by the first connecting vertical plate 214b extending in the vertical direction, it has high strength against forces from above.

[0057] The load receiving member 23 is placed on the first connecting horizontal plate 214a and the first protruding horizontal plate 214c, and a base 231 of the load receiving member 23 is attached with mounting screws 237. A cover tube 232 is fixed to the top of the base 231 of the load receiving member 23, and a spring 233 is housed inside it. A spring upper surface plate 234 is placed on top of the spring 233. The height of the spring 233 is higher than that of the cover tube 232, and in FIG. 8, part of the spring 233 is visible between the cover tube 232 and the spring upper surface plate 234. An adjustment bolt 235 is installed from the spring upper surface plate 234, passing through the center of the spring 233, the base 231, and the mounting base 214. By tightening the lower part of the adjustment bolt 235 with an adjustment nut 236, the head of the adjustment bolt 235 presses down the spring upper surface plate 234. This allows the spring 233 to be compressed to change the height of the spring upper plate 234, and also allows adjustment so that the spring 233 does not compress to a predetermined load.

[0058] 8, the load piece 226 of the second member 22 has a second connecting vertical plate 226b extending in the vertical direction, a second connecting horizontal plate 226a extending in the horizontal direction and connected to the second connecting vertical plate 226b, and a second protruding horizontal plate 226c extending in the horizontal direction from the second connecting horizontal plate 226a, and is formed into an L-shaped plate. The load piece 226 has the second connecting horizontal plate 226a extending in the horizontal direction indicated by diagonal lines, and the second connecting vertical plate 226b bending and extending upward from the second connecting horizontal plate 226a, which are fixed to the second side panel 221 on both sides by welding. On the other hand, the second protruding horizontal plate 226c, which extends laterally from the second connecting horizontal plate 226a into the first member 21 on the opposite side of the second connecting vertical plate 226b, is not directly fixed to the second side surface plate 221, but is fixed to the second side surface plate 221 via the second connecting horizontal plate 226a and the second connecting vertical plate 226b. The second protruding horizontal plate 226c protrudes from the second member 22 in the direction of the first member 21.

[0059] The load piece 226 is fixed to the second side panel 221 between the two second side panels 221 not only by the second connecting horizontal panel 226a but also by the second connecting vertical panel 226b extending vertically. This provides high strength against forces from below. The load piece 226 has the second connecting vertical panel 226b positioned above the second connecting horizontal panel 226a and reaching the side of the upper link 241. Therefore, the load piece 226 firmly connects the two second side panels 221 near the link mounting hole 221a (shown in FIG. 5) to which the upper link 241 is attached and to which force acts. The load piece 226 has the second connecting vertical panel 226b positioned to the side of the workbench mounting portion 223 (shown in FIG. 5). This firmly connects the two second side panels 221 near the workbench mounting portion 223 (shown in FIG. 5) to which force acts.

[0060] As shown in FIG. 8, the load-receiving member 23 is located between the center of the upper link 241 and the center of the lower link 242. In the unloaded state shown in FIG. 8, the vertical center axis of the load-receiving member 23 (the same as the center axis of the spring 233 and the center axis of the adjustment bolt 235) is located near the gap between the first side panel 211 and the second side panel 221 when viewed from the side. This allows the load-receiving member 23 to be housed in a balanced manner between the first member 21 and the second member 22. This allows the radius of the spring 233 to be increased. The load-receiving member 23 is located between the two first side panels 211 and the two second side panels 221 and receives a load between the mounting base 214 and the load piece 226. The load-receiving member 23 is provided on the second member 22 side of the leveling link mounting hole 211a shown in FIGS. 2 and 4.

[0061] An L-shaped detector fixing plate 227 having a fixing hole (not shown) is fixed to the upper side of a second connecting plate 225 provided on the upper part of the second member 22. A switch 261 is attached to the switch fixing piece 262 on the back side of the switch fixing piece 262 in FIG. 8. An overload is detected when the switch 261 is activated. The switch 261 is a limit switch, and a switch button 261a provided below the switch 261 is positioned above the first connecting plate 213. When the switch 261 is lowered and the switch button 261a is pressed by the first connecting plate 213, the switch 261 is activated and detects an overload.

[0062] The switch mounting piece 262 is fixed so that its height can be adjusted by being sandwiched between two vertical nuts 266 fixed to a vertical bolt 265 attached to the protrusion 225a of the second connecting plate 225. In addition, the switch mounting piece 262 is fixed so as not to rotate even when the switch button 261a abuts against the first connecting plate 213 by a horizontal bolt 263 inserted into a vertically elongated fixing hole (not shown) in the switch mounting piece 262 and a fixing hole (not shown) in the detection unit fixing plate 227, and a horizontal nut 264 located on the back side of the horizontal bolt 263. The fixing hole provided in the detection unit fixing plate 227 is formed larger than the body of the horizontal bolt 263.

[0063] The second connecting horizontal plate 226a and the second protruding horizontal plate 226c of the load piece 226 are placed on the spring upper surface plate 234 of the load receiving member 23. The load of the workbench 14 shown in FIG. 1 is transmitted from the workbench mounting portion 223 shown in FIGS. 3 and 5 to the second member 22, and the load piece 226 shown in FIGS. 5 and 8 presses the spring upper surface plate 234 of the load receiving member 23 downward. The pressed spring upper surface plate 234 descends as the spring 233 contracts in response to the pressing force. This causes the second member 22 to descend relative to the first member 21, and the switch 261 to descend. When the switch button 261a of the switch 261 is pressed by the first connecting plate 213, the switch 261 is turned on and an overload is detected. As described above, in the load detection device 2, the contraction of the spring 233 causes the second member 22 to descend relative to the first member 21, and the switch 261 is activated to detect an overload.

[0064] The second member 22 is connected to the first member 21 by a parallel link 24 so as to be movable up and down, and as shown in Fig. 8, there is a gap between the first side plate 211 and the second side plate 221 when no load is applied. When the spring 233 contracts, the second member 22 descends relative to the first member 21 while changing the gap between the first side plate 211 and the second side plate 221. At this time, there is a slight sliding movement between the load piece 226 and the spring upper surface plate 234.

[0065] A lower stopper receiver 215 is provided at the bottom of the first member 21, and a lower stopper portion 228 is provided at the bottom of the second member 22. When a large load is applied, the lower stopper portion 228 of the second member 22 is supported from below by the lower stopper receiver 215 of the first member 21, stopping the second member 22 from descending relative to the first member 21. In this way, the lower stopper receiver 215 and the lower stopper portion 228 located above the lower stopper receiver 215 restrict downward movement of the second member 22 relative to the first member 21. In the load detection device 2, the lower stopper receiver 215 and the lower stopper portion 228 prevent excessive upward force from being applied to the switch 261 due to excessive descent. In addition, the first stopper portion 212 and the second stopper portion 222 located below the first stopper portion 212, as shown in FIGS. 2, 4, 5, etc., restrict upward movement of the second member 22 relative to the first member 21.

[0066] The gap distance between the first side panel 211 and the second side panel 221, as seen from the side in Fig. 2, changes depending on the load state of the second member 22 to which the workbench 14 is connected, but the stopper ensures this gap even when the load exceeds an overload or when vertical vibration occurs during travel, etc. Therefore, the first opposing surface 211c of the first member 21 and the second opposing surface 221b of the second member 22 do not come into contact. This prevents the first side panel 211 and the second side panel 221 from coming into contact with each other in a state exceeding an overload or when vertical vibration occurs, preventing excessive force from acting on the parallel link 24 or the link pin 25.

[0067] When adjusting the load, which is the limit of the load that does not become an overload, the height of the switch 261 is adjusted. To adjust the height of the switch 261, loosen the horizontal nut 264 in the load detection unit 26, place a weight of an appropriate weight on the workbench 14, and then adjust the height of the switch mounting piece 262 with the vertical bolt 265 and vertical nut 266. By adjusting the height of the switch mounting piece 262 and the height of the switch button 261a, variations in the spring constant of the spring 233 are absorbed, thereby stabilizing the load at which the switch 261 operates. The height of the switch mounting piece 262 is then adjusted so that the switch 261 operates when a predetermined load slightly greater than the rated load is reached. Because the load detection unit 26 in this embodiment is provided on the load detection device 2, the height of the switch 261 can be easily adjusted. However, the load detection unit 26 may be provided in another position.

[0068] The load-receiving member 23 has a spring force adjustment mechanism using an adjustment bolt 235 and an adjustment nut 236. If the distance between the adjustment bolt 235 and the adjustment nut 236 is adjusted to compress the spring 233, the spring 233 will not compress until the load reaches the repulsive force of the contraction. The spring 233 begins to compress once the load from the workbench 14 reaches the repulsive force of the contraction caused by the spring force adjustment mechanism. If the distance between the adjustment bolt 235 and the adjustment nut 236 is shortened to increase the contraction of the spring 233, the load at which the load-receiving member 23 begins to contract will increase. Conversely, if the distance between the adjustment bolt 235 and the adjustment nut 236 is lengthened to decrease the contraction of the spring 233, the load at which the load-receiving member 23 begins to contract will decrease. By adjusting the spring force at the start of contraction using the spring force adjustment mechanism using the adjustment bolt 235 and the adjustment nut 236, the spring 233 of the load-receiving member 23 can begin to contract at a weight just before it becomes overloaded. The spring force adjustment mechanism adjusts the load at which the spring begins to contract, thereby reducing the amount of stroke change when detecting an overload, and also suppressing the expansion and contraction of the spring 233 due to acceleration while the aerial work platform 1 is traveling.

[0069] Furthermore, when the swivel base 12 or boom 13 moves or when the worker moves on the work platform 14, a force is generated in the vertical direction on the work platform 14. Without a spring force adjustment mechanism, the spring that receives the load in the load detection device 2 expands and contracts every time the vertical force changes, which could result in increased vibration of the work platform 14. Because the load receiving member 23 of the embodiment has a spring force adjustment mechanism, the spring 233 does not contract until just before an overload occurs, and vertical vibration of the work platform 14 due to the elasticity of the spring 233 is unlikely to occur. The load receiving member 23 equipped with the spring force adjustment mechanism is positioned in a balanced position between the first member 21 and the second member 22.

[0070] Although the switch 261 in the embodiment is a limit switch equipped with a switch button 261a, other switches may also be used. Alternatively, a load cell may be provided instead of the switch 261, and an overload may be detected from the pressure applied to the load cell. Furthermore, the load detection unit 26 may detect a change in the position of the second member 22 relative to the first member 21 to detect the load caused by the workbench 14. In this case, the position of the adjustment nut 236 relative to the adjustment bolt 235 is adjusted by the spring force adjustment mechanism of the load receiving member 23 so that the upward force caused by the load received by the load receiving member 23 when the workbench 14 is empty is equal to the downward force caused by the load. This causes the spring 233 to contract by the amount of the load placed on the workbench 14. Meanwhile, when the workbench 14 is lowered by the boom 13, the load on the load receiving member 23 decreases, but the spring 233 does not expand, preventing the workbench 14 from becoming unstable.

[0071] 2, 4, and 5, the first stopper portion 212 is formed by the recess 211d of the first side panel 211, and the second stopper portion 222 is formed by the protrusion 221c of the second side panel 221, as a stopper that suppresses the rise of the second member 22. However, these stoppers do not have to be formed as part of the first side panel 211 or the second side panel 221, but may be formed as members fixed to the first side panel 211 or the second side panel 221, or may be formed as members fixed to other structures. Furthermore, the stopper formed by the lower stopper receiver 215 and the lower stopper portion 228 may also have other structures.

[0072] Furthermore, the specific configuration is not limited to the embodiments, and the present invention includes design changes and the like within the scope of the gist of the present invention. Furthermore, the above-described embodiments and modifications can be combined by utilizing each other's technologies as long as there are no particular contradictions or problems in the purpose, configuration, etc. [Explanation of symbols]

[0073] 1. Aerial work platform 11 vehicles 12 Swivel table 13. Boom 131 Lower boom 132 Upper boom 14 Workbench 15 Outrigger 2. Load detection device 21 First member 211 1st side plate 211a Leveling link mounting hole 211b Link mounting hole 211c 1st facing surface 211d recess 212 First stopper part 213 First connecting plate 213a Recess 214 Mounting table 214a First connecting horizontal board 214b First connecting vertical plate 214c 1st protruding horizontal plate 214d Adjustment screw hole 214e Mounting hole 215 Lower stopper holder 216 Boom mounting boss 216a Boom mounting hole 22 Second member 221 2nd side plate 221a Link mounting hole 221b Second facing surface 221c convex part 222 Second stopper part 223 Workbench mounting part 223a Shaft hole 224 Angle change bar 225 Second connecting plate 225a Convex part 226 Load piece 226a Second connecting horizontal board 226b Second connecting vertical plate 226c 2nd protruding horizontal plate 227 Detector fixing plate 228 Lower stopper part 23 Load-bearing member 231 Foundation 232 Cover tube 233 Spring 234 Spring upper plate 235 Adjustment bolt 236 Adjustment nut 237 Mounting screw 24 Parallel link 241 Top Link 241a Link body 241b Link shaft 242 bottom link 242a Link body 242b Link shaft 25 link pin 26 Load detection unit 261 Switch 261a Switch button 262 Switch mounting piece 263 Horizontal bolt 264 Side nut 265 Vertical Bolt 266 Vertical Nut 267 Fixing screw

Claims

1. The aerial work platform includes a first member located on the boom side of the aerial work vehicle, a second member located on the work platform side of the aerial work vehicle, a load receiving member, a load detecting unit, and a parallel link formed by an upper link and a lower link, the second member is connected to the first member by the parallel link so as to be movable in the up and down direction, the first member has two first side plates and a mounting base that is connected and fixed between the first side plates, the second member has two second side plates and a load piece connected and fixed between the two second side plates; the load-receiving member is positioned between the two first side plates and the two second side plates, and receives a load between the mounting table and the load piece; The first side panel and the second side panel do not overlap when viewed from the side. A load detection device characterized by:

2. The gap distance between the first side panel and the second side panel, as viewed from the side, changes depending on the load state, and the stopper ensures the gap even when an overload is exceeded or vertical vibration occurs during driving, etc.

2. The load detection device according to claim 1.

3. The first side plate and the second side plate are provided on the same plane.

3. The load detection device according to claim 2.

4. The load-receiving member is located between the center of the upper link and the center of the lower link.

2. The load detection device according to claim 1.

5. When no load is applied, a vertical center axis of the load-receiving member is disposed in the vicinity of a gap between the first side panel and the second side panel as viewed from the side.

2. The load detection device according to claim 1.

6. the first side panel has a generally inverted triangular shape, A boom mounting hole is provided in an upper portion of the first member, and a leveling link mounting hole is provided at a position diagonally below the boom mounting hole, the load-receiving member is provided on the second member side with respect to the leveling link mounting hole; 2. The load detection device according to claim 1.

7. The mounting base and the load piece are formed by an L-shaped plate, the mounting base includes a first connecting vertical plate extending in a vertical direction, a first connecting horizontal plate extending in a horizontal direction and connected to the first connecting vertical plate, and a first protruding horizontal plate extending from the first connecting horizontal plate; the first connecting vertical plate and the first connecting horizontal plate are fixed to the first side plate, the first protruding horizontal plate protrudes from the first member toward the second member, The load piece has a second connecting vertical plate extending in a vertical direction, a second connecting horizontal plate extending in a horizontal direction and connected to the second connecting vertical plate, and a second protruding horizontal plate extending from the second connecting horizontal plate, the second connecting vertical plate and the second connecting horizontal plate are fixed to the second side plate, The second protruding horizontal plate protrudes from the second member toward the first member.

7. The load detection device according to claim 6.

Images