High altitude work vehicle

Abstract

To provide a high altitude work vehicle capable of more accurately measuring a load applied to a work platform.SOLUTION: A high altitude work vehicle supports a work platform at the tip of the boom so that it can move up and down via a parallel link mechanism composed of a boom vertical member, an upper horizontal link member, a lower horizontal link member, and a work platform fixing member. The high altitude work vehicle comprises a coil spring attached between the boom vertical member and the work platform fixing member that expands and contracts in response to the load on the work platform, a left potentiometer 62L and a right potentiometer 62R that output detection values in response to the vertical displacement of the work platform due to the expansion and contraction of the coil spring, and a load measuring device 101 that measures the load on the work platform based on the detection values output from the left potentiometer 62L and the right potentiometer 62R.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a vehicle for working at height that supports a work platform that can swing up and down via a parallel link mechanism at the tip of a boom that is provided on a vehicle body and can be raised and lowered. [Background technology]

[0002] Conventionally, there are aerial work platforms that support a work platform at the tip of a boom via a parallel link mechanism so that the work platform can swing up and down. Some of these aerial work platforms have a parallel link mechanism that is pivotally connected to a bracket attached to the tip of the boom, a boss formed on the work platform, an upper link member, and a lower link member (see, for example, Patent Document 1). In the aerial work platform of Patent Document 1, a load cell is disposed between the bracket and the boss, which is the movable part of the parallel link mechanism, and the load of the work platform is detected by the load cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-67099 Summary of the Invention [Problem to be solved by the invention]

[0004] In the aerial work platform described in Patent Document 1, the load on the work platform is detected by a single load cell, so there is a risk that the value of the load detected by the load cell will deviate from the actual load applied, for example, if a torsional load occurs depending on the location where the load is applied to the work platform.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide an aerial work platform that can more accurately measure the load applied to the work platform. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a vehicle for working at heights comprising a work platform attached via a parallel link mechanism to the tip of a boom that is provided on a vehicle body and can be raised and lowered freely, the parallel link mechanism comprising a boom-side vertical member that is pivotally connected to the tip of the boom and extends vertically, an upper horizontal link member that is pivotally connected at its base end to the boom-side vertical member and extends horizontally, a work platform-side vertical member that is pivotally connected to the tip of the upper horizontal link member and extends vertically, and to which the work platform is fixed, and a work platform-side vertical member that is located below the upper horizontal link member and extends horizontally, its base end is pivotally connected to the boom-side vertical member and its tip end is connected to the work platform. and a lower horizontal link member pivotally connected to the platform side vertical member, so that the work platform can be displaced in the vertical direction relative to the boom side vertical member, and is equipped with a coil spring attached between the boom side vertical member and the work platform side vertical member that expands and contracts according to the load on the work platform, a plurality of detectors (e.g., potentiometer 62 and transmission mechanism 61 in the embodiment) that output detection values ​​according to the vertical displacement of the work platform due to the expansion and contraction of the coil spring, and a load measuring device (e.g., load measuring unit 101 in the embodiment) that measures the load on the work platform based on the detection values ​​output from the plurality of detectors.

[0007] Furthermore, in an aerial work vehicle of the above configuration, it is preferable that the multiple detectors are arranged at positions spaced apart across the displacement plane in a direction perpendicular to the vertical displacement plane of the work platform at the pivot point between the tip of the boom and the boom side vertical member.

[0008] In the aerial work vehicle having the above-described configuration, it is preferable that the load measuring device performs processing to reduce deviations in the detected values ​​output from the plurality of detectors.

[0009] In addition, in the aerial work vehicle of the above configuration, it is preferable that the load measuring device determines the center of gravity position when a load is applied to the work platform based on the difference in magnitude of each detection value output from the multiple detectors.

[0010] Furthermore, in an aerial work vehicle of the above configuration, it is preferable to provide multiple types of sensors that detect the posture of the aerial work vehicle (for example, in the embodiment, a rotation angle sensor 71, a derrick angle sensor 72, an extension amount sensor 73, a swivel angle sensor 74, a work platform inclination sensor 75, and a vehicle body inclination sensor 76), and an operation control device (for example, in the embodiment, an operation control unit 102) that controls the travel of the vehicle body and the operation of the boom based on the detection values ​​of each of the multiple types of sensors, the load on the work platform measured by the load measuring device, and the center of gravity position of the work platform determined by the load measuring device.

[0011] Furthermore, in an aerial work platform having any of the above configurations, it is preferable that the detector is composed of a rotary potentiometer having a rotating shaft and whose resistance value changes depending on the rotation angle of the rotating shaft, a crank member having one end fixed to the rotating shaft of the potentiometer, and a connecting member (for example, connecting shaft 612 in the embodiment) having one end rotatably attached to the other end of the crank member and the other end rotatably attached to the vertical member on the work platform side. [Effects of the Invention]

[0012] According to the aerial work vehicle of the present invention, a coil spring is attached between the boom side vertical member and the work platform side vertical member that constitute the parallel link mechanism, and when this coil spring expands and contracts in accordance with the load on the work platform, the resulting vertical displacement of the work platform is detected by multiple detectors, and the load on the work platform is measured based on the detection values ​​output from each detector, making it possible to measure the load with higher accuracy than when measuring the load using a single load detector (e.g., a load cell).

[0013] In the vehicle for working at height having the above-described configuration, preferably, a plurality of detectors are disposed at positions spaced apart across the displacement plane in a direction perpendicular to the vertical displacement plane of the work platform at the pivot point between the tip of the boom and the boom-side vertical member constituting the parallel link mechanism, whereby the position of the center of gravity of the work platform can be determined based on the difference in detection values ​​from the plurality of detectors.

[0014] In addition, in the aerial work platform configured as described above, it is preferable to perform processing to reduce the deviation of the detected values ​​output from the multiple detectors. This makes it possible to measure a load that is close to the actual load, even if the detected values ​​output from the multiple detectors vary due to, for example, a torsional load occurring on the work platform.

[0015] Furthermore, the vehicle for aerial work configured as described above preferably includes multiple types of sensors that detect the attitude of the vehicle for aerial work, and an operation control device that controls the travel of the vehicle body and the operation of the boom based on the detected values ​​of the multiple types of sensors, the load of the work platform measured by the load measuring device, and the position of the center of gravity of the work platform determined by the load measuring device. This allows more conditions to be taken into account when determining the range in which the boom can be operated safely without the vehicle for aerial work tipping over, so there is no need to leave more margin than necessary in the operable range of the boom, and as a result the operable range of the boom can be expanded, allowing the boom to be used more effectively.

[0016] In addition, in any of the above-described aerial work platforms, the detector preferably comprises a rotary potentiometer whose resistance value changes according to the rotation angle of the rotary shaft, a crank member having one end fixed to the rotary shaft of the potentiometer, and a connecting member having one end rotatably attached to the other end of the crank member and the other end rotatably attached to the work platform vertical member, thereby enabling the detector to be constructed at lower cost. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a side view showing the appearance of an aerial work platform equipped with a work platform load detection device according to the present invention. [Figure 2] FIG. 2 is a side view showing the configuration of the boom tip, parallel link mechanism, and work platform of the aerial work platform of the vehicle for high altitude work. [Figure 3] FIG. 2 is a perspective view showing the configuration of a boom tip and a parallel link mechanism of the aerial work vehicle. [Figure 4] FIG. 3 is an exploded side view showing the configuration of the parallel link mechanism of the aerial work vehicle. [Figure 5] FIG. 4 is a plan view showing the mounting position of a potentiometer on the vehicle for working at high altitude. [Figure 6] 4 is a perspective view showing the appearance of a transmission mechanism that transmits the displacement amount of the work platform of the aerial work platform vehicle to a potentiometer. FIG. [Figure 7] 3 is a block diagram showing the configuration of a controller that controls each part of the aerial work platform. FIG. [Figure 8] 10 is a graph showing the relationship between the load applied to the work platform of the aerial work platform vehicle and the measured load. [Figure 9] 10 is an explanatory diagram for explaining the determination result of the center of gravity position of the work platform of the aerial work vehicle. FIG. [Figure 10] 10 is a flowchart showing a load measurement process executed in a controller of the aerial work platform. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a side view of a self-propelled vehicle for aerial work 1 as an example of a vehicle for aerial work according to an embodiment of the present invention. In this figure, the length of a boom 30 is partially omitted. In the following description with reference to FIG. 1, the front-to-back, up-and-down directions will follow the arrows in the figure. The direction from the front to the back of the page in FIG. 1 will be referred to as the "right," and the direction from the back to the front of the page in FIG. 1 will be referred to as the "left." The vehicle for aerial work 1 shown in FIG. 1 is configured to include a traveling platform 10, a rotating platform 20 provided on top of the traveling platform 10 and capable of rotating in the horizontal direction, a boom 30 provided on top of the rotating platform 20 and capable of raising and lowering, a parallel link mechanism 40 provided at the tip of the boom 30, and a work platform 50.

[0019] The running body 10 has a pair of left and right steering wheels 12 rotatably mounted on the running body frame 11, and a pair of left and right drive wheels 13, and is propelled by a running motor 14 (see FIG. 7), which will be described later. A slewing mechanism 15 is provided in the center of the upper part of the running body frame 11, and is configured to be able to swivel a rotating body 20 in the horizontal direction by the slewing mechanism 15. The slewing mechanism 15 has an outer wheel fixed to the running body frame 11, an inner wheel engaged with the outer wheel and fixed to the rotating body 20, and a rotary center joint (not shown) for supplying hydraulic oil to various actuators provided on the running body 10, and swivels the rotating body 20 by a slewing motor 16 (see FIG. 7), which will be described later. A boom 30 is provided on the upper part of the rotating body 20, and the boom 30 is able to swing (raise and lower) in the vertical direction about a pivot pin 21.

[0020] The boom 30 has a base boom 30a pivotally connected to the rotating body 20, an intermediate boom 30b and a tip boom 30c that are combined with the base boom 30a in a telescopic manner, and each of these booms is configured to be telescopic. The base boom 30a (and by extension the entire boom 30) is raised and lowered by extension of the hoisting cylinder 22. A telescopic cylinder 23 (see Figure 7) is provided inside the base boom 30a, and extension and contraction of the telescopic cylinder 23 causes the intermediate boom 30b and the tip boom 30c to extend and retract relative to the base boom 30a.

[0021] Next, with reference to Figure 2, the configuration for supporting the work platform 50 at the tip of the boom 30 will be described. Here, Figure 2 is a side view showing the side of the tip of the boom 30 including the work platform 50. The front-to-back and up-to-down directions in this figure are indicated by arrows in the figure, with the direction from the front of the page in Figure 2 to the back being the "right" and the direction from the back to the front being the "left". In Figure 2, the same components as in Figure 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0022] 2, a boom head 31 is provided at the tip of the tip boom 30c, and the boom head 31 is pivotally connected to a work platform support member 32 by a pivot pin 31a. The work platform support member 32 is also pivotally connected to a piston rod 33 of a boom-side leveling cylinder (not shown) provided inside the tip boom 30c by a pivot pin 33a. The piston rod 33 of the boom-side leveling cylinder is extended and retracted in accordance with the raising and lowering movement of the boom 30 to control the leveling of the work platform 50, so that the work platform 50 can be swung up and down in accordance with the raising and lowering movement of the boom 30 while keeping the floor surface of the work platform 50 horizontal.

[0023] A swing motor 34 for swinging (swinging horizontally) the workbench 50 is provided at the tip of the workbench support member 32. A vertical post 35 (see FIG. 4) is provided inside the swing motor 34, and the vertical post 35 supports the workbench 50 via a parallel link mechanism 40 so that it can swing horizontally. The swing motor 34 swings the parallel link mechanism 40 horizontally to the left and right about the vertical post 35 as an axis (rotating the parallel link mechanism 40 about the vertical post 35 as an axis), thereby enabling the swinging of the workbench 50. The parallel link mechanism 40 also allows the workbench 50 to swing up and down relative to the tip of the workbench support member 32 while keeping the floor surface horizontal.

[0024] The parallel link mechanism 40 mainly comprises a boom-side vertical member 41 fixed to the vertical post 35, a platform fixing member 52 to which the platform 50 is fixed, and an upper horizontal link member 42 and a lower horizontal link member 43. The boom-side vertical member 41 and the platform fixing member 52 are connected to each other by the upper horizontal link member 42 and the lower horizontal link member 43. The platform 50 is provided with an operating device 51, which an operator on the platform 50 can use to control the travel of the running unit 10, the rotation of the rotating unit 20, the elevation and descent of the boom 30, and the swing of the platform 50, as shown in FIG. 1 . Due to the position of the operating device 51 on the platform 50, the operator on the platform 50 faces left in the figure to operate the vehicle for aerial work 1. Therefore, the "forward" direction indicated by the arrows in FIGS. 1 and 2 is the forward direction of the vehicle for aerial work 1, and the "rear" direction is the reverse direction.

[0025] Next, the parallel link mechanism 40 and its surrounding structure will be described with reference to Figures 3 to 5. Here, Figure 3 is a perspective view of the tip of the boom 30 as seen obliquely from the front, with the work platform 50 omitted from the drawing. Figure 4 is an exploded side view of the structure of the parallel link mechanism 40. Figure 5 is a plan view schematically showing the boom-side vertical member 41 constituting the parallel link mechanism 40 as seen from above. The up-down, front-rear, left-right directions in Figure 3 follow the arrows shown in the figure. The front-rear, up-down, left-right directions in Figure 4 are the same as those in Figure 2. The front-rear, left-right directions in Figure 5 follow the arrows shown in the figure. Furthermore, in Figure 3, the same components as those in Figures 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0026] As shown in FIGS. 3 and 4, the parallel link mechanism 40 includes a boom-side vertical member 41 and an upper The boom-side vertical member 41 is composed of a horizontal link member 42, a lower horizontal link member 43, and a work platform fixing member 52. The boom-side vertical member 41 is swivellably fixed to a vertical post 35 (see FIG. 4) provided on the work platform support member 32, thereby attaching the parallel link mechanism 40 to the tip of the boom 30. A work platform 50 is fixed to the work platform fixing member 52. The boom-side vertical member 41 is composed of a left side plate 411L, a right side plate 411R (see FIG. 5), an upper flat plate 415, and a lower flat plate 416. The left side plate 411L and the right side plate 411R have the same shape and are arranged facing each other with a predetermined distance between them. The upper flat plate 415 and the lower flat plate 416 are attached horizontally between the left side plate 411L and the right side plate 411R. As shown in FIG. 4, the upper end of the vertical post 35 is fixed to the upper flat plate 415, and the lower end of the vertical post 35 is fixed to the lower flat plate 416.

[0027] As shown in FIG. 4, an upper pivot hole 412 for receiving the boom-side upper pivot pin 421 (see FIG. 3) is provided in the upper part of the left side plate 411L, and a lower pivot hole 413 for receiving the boom-side lower pivot pin 431 is provided in the lower part of the left side plate 411L. A fan-shaped left opening 414L is provided between the upper pivot hole 412 and the upper flat plate 415. Although not shown in FIG. 4, the right side plate 411R also has an upper pivot hole 412, a lower pivot hole 413, and a right opening 414R at positions facing the upper pivot hole 412, the lower pivot hole 413, and the left opening 414L provided in the left side plate 411L. A spring lower end receiver 417 for receiving the lower end of the spring 60 shown in FIG. 4 is attached to the upper surface of the upper flat plate 415.

[0028] As shown in Figure 4, an upper pivot hole 521 and a lower pivot hole 522 are formed on the left and right side surfaces of the work platform fixing member 52 when viewed from the direction shown in Figure 3. These upper pivot holes 521 and lower pivot holes 522 are provided at opposing positions on the left and right side surfaces of the work platform fixing member 52. The vertical distance between the upper pivot holes 521 and the lower pivot holes 522 is the same as the vertical distance between the upper pivot holes 412 and the lower pivot holes 413 formed on the left plate 411L and right plate 411R of the boom side vertical member 41. A horizontal plate 523 is provided below the upper pivot hole 521, extending from the left side surface to the right side surface of the work platform fixing member 52, and a spring upper end receiver 524 to which the upper end of the spring 60 is attached is formed on the lower surface of the horizontal plate 523.

[0029] As shown in FIGS. 3 and 4, the upper horizontal link member 42 is composed of an upper left side plate 420L, an upper right side plate 420R, a boom-side pivot pin 421, and a platform-side pivot pin 422. The upper left side plate 420L and the upper right side plate 420R have the same shape and are each provided with a boom-side pivot pin hole into which the boom-side pivot pin 421 shown in FIG. 4 is inserted and a platform-side pivot pin hole into which the platform-side pivot pin 422 is inserted. As a result, the boom-side pivot pin holes in the upper left side plate 420L and the upper right side plate 420R are aligned with the upper pivot holes 412 in the left side plate 411L and right side plate 411R of the boom-side vertical member 41, and the boom-side pivot pin 421 is inserted through the holes to pivotally connect the upper horizontal link member 42 to the boom-side vertical member 41. In addition, split pins SP are attached to both ends of the boom-side pivot pin 421. On the workbench 50 side, the positions of the workbench side pivot pin holes provided on the upper left side plate 420L and the upper right side plate 420R are aligned with the positions of the upper pivot holes 521 provided on the workbench fixing member 52, and the workbench side pivot pin 422 is passed through and fixed, thereby pivoting the upper horizontal link member 42 to the workbench fixing member 52.

[0030] Like the upper horizontal link member 42, the lower horizontal link member 43 is also made up of a lower left side plate 430L and a lower right side plate (not shown), a boom side pivot pin 431 and a platform side pivot pin 432. The lower left side plate 430L and the lower right side plate have the same shape, and each is provided with a boom side pivot pin hole into which the boom side pivot pin 431 shown in Figure 4 is inserted, and a platform side pivot pin hole into which the platform side pivot pin 432 is inserted. As a result, The positions of the boom side pivot pin holes formed in the lower left side plate 430L and the lower right side plate are aligned with the positions of the lower pivot holes 413 formed in the left side plate 411L and right side plate 411R of the boom side vertical member 41, and the boom side pivot pin 431 is passed through, thereby pivotally connecting the lower horizontal link member 43 to the boom side vertical member 41. In addition, split pins SP are attached to both ends of the boom side pivot pin 431. On the work platform 50 side, the positions of the work platform side pivot pin holes formed in the lower left side plate 430L and the lower right side plate are aligned with the positions of the lower pivot holes 522 formed in the work platform fixing member 52, and the work platform side pivot pin 432 is passed through, thereby pivotally connecting the lower horizontal link member 43 to the work platform fixing member 52.

[0031] The parallel link mechanism 40 described above is provided with a spring 60, a transmission mechanism 61, and a potentiometer 62 as components for detecting the load on the work platform 50. The spring 60 is a compression coil spring, and is attached between a spring lower end receiver 417 provided on the boom side vertical member 41 and a spring upper end receiver 524 provided on the work platform fixing member 52 when the upper horizontal link member 42 and the lower horizontal link member 43 are pivotally connected to the boom side vertical member 41 and the work platform fixing member 52.

[0032] 5, the potentiometer 62 includes a right-side potentiometer 62R attached to the right side plate 411R and a left-side potentiometer 62L attached to the left side plate 411L. Hereinafter, when describing content common to the right-side potentiometer 62R and the left-side potentiometer 62L or when describing both together without distinguishing between them, the letters "R" and "L" added to the end of the reference numerals will be omitted. The potentiometer 62 is a rotary potentiometer having a rotating shaft RS with a male thread formed at its tip, and is configured to obtain a voltage signal corresponding to the rotation angle of the rotating shaft RS.

[0033] As shown in Fig. 5, a right-side potentiometer 62R is attached to the right side plate 411R so that its rotation axis RS protrudes from the right-side opening 414R, and a left-side potentiometer 62L is attached to the left side plate 411L so that its rotation axis RS protrudes from the left-side opening 414L. Here, the rotation axis RS of the right-side potentiometer 62R and the rotation axis RS of the left-side potentiometer 62L are attached to the right side plate 411R and the left side plate 411L, respectively, so that they coincide with a single rotation axis AR indicated by a dashed line. Furthermore, the distance from the center line CL to the mounting position of the right-side potentiometer 62R is equal to the distance from the center line CL to the mounting position of the left-side potentiometer 62L, and the distance from the center line CL to the position of the left mounting hole BH (see Fig. 4) is equal to the distance from the center line CL to the position of the right-side mounting hole BH. In other words, the mounting position of the left potentiometer 62L and the position of the left mounting hole BH and the mounting position of the right potentiometer 62R and the position of the right mounting hole BH are in a line-symmetrical relationship with respect to the center line CL. Here, the center line CL indicates the position of the vertical displacement plane of the work platform 50 at the center of the vertical post 35 (the pivot point between the work platform support member 32 and the boom-side vertical member 41), and the rotation axis AR is an axis extending in a direction perpendicular to the center line CL.

[0034] The transmission mechanism 61 transmits the vertical movement of the workbench fixing member 52 to the rotation shaft RS of the potentiometer 62, and is composed of a crank member 610, an upper spacer 611, a connecting shaft 612, and a lower spacer 613, as shown in FIG. 6. A mounting hole CH is formed in one end of the crank member 610, and the rotation shaft RS of the potentiometer 62, which protrudes from the opening 414, is passed through this mounting hole CH, and the rotation shaft RS is fixed to the crank member 610 by a nut NT1 shown in FIG. 4. An upper spacer 611 is fixed to the other end of the crank member 610, and the upper spacer 611 is fixed to an upper connecting portion 612a of a connecting shaft 612 so as to be rotatable relative to the upper connecting portion 612a. A lower spacer 613 is rotatably fixed to a lower connecting portion 612b of the connecting shaft 612. A male thread MC is formed at the tip of the lower spacer 613, and the male thread MC is fixed to the workbench fixing member 52 formed therein by a nut NT2 shown in FIG. 4. It is fixed to mounting hole BH.

[0035] According to the above configuration, when a load is applied to the workbench 50, the workbench fixing member 52 is displaced downward, and the amount of this displacement is converted by the transmission mechanism 61 into a rotation angle of the rotation axis RS of the potentiometer 62. As a result, a voltage signal having a voltage value corresponding to the rotation angle of the rotation axis RS is generated by the potentiometer 62, and based on this voltage signal, the controller 100 (see FIG. 7), which will be described later, measures the load applied to the workbench 50 and determines the position of the center of gravity of the workbench 50. The processes executed by the controller 100 to measure the load on the workbench 50 and determine the position of the center of gravity will be described in detail later.

[0036] Next, the general configuration of each section that controls the operation of the vehicle for aerial work 1 will be described with reference to the block diagram shown in Figure 7. The controller 100 shown in this figure controls the operation of various hydraulic actuators such as the travel motor 14, swing motor 16, derrick cylinder 22, telescopic cylinder 23, and swing motor 34 described above, based on the operation of the various control levers and switches provided on the operation device 51 shown in Figure 1. A memory card 52, which is a removable recording medium, is attached to the operation device 51, and as will be described later, the load and center of gravity position of the work platform 50 measured by the controller 100 while the vehicle for aerial work 1 is in operation can be stored in the memory card 52.

[0037] The aerial work vehicle 1 is equipped with a hydraulic unit 25 for operating the various hydraulic actuators described above. This hydraulic unit 25 is composed of a hydraulic pump 26 that discharges hydraulic oil, a pump drive motor 27 that drives the hydraulic pump 26, and a group of control valves 28 that control the supply direction and amount of hydraulic oil supplied from the hydraulic pump 26 to each hydraulic actuator. The pump drive motor 27 is driven and rotated by AC power supplied from a battery 80 via an inverter 81. Drive control of the pump drive motor 27 is performed by a controller 100 adjusting the power output from the inverter 81 to the pump drive motor 27.

[0038] The control valve group 28 includes an electromagnetic proportional control valve V1 that controls the hydraulic oil supplied to the travel motor 14, an electromagnetic proportional control valve V2 that controls the hydraulic oil supplied to the swing motor 16, an electromagnetic proportional control valve V3 that controls the hydraulic oil supplied to the hoisting cylinder 22, an electromagnetic proportional control valve V4 that controls the hydraulic oil supplied to the telescopic cylinder 23, and an electromagnetic proportional control valve V5 that controls the hydraulic oil supplied to the swing motor 34. Each of the electromagnetic proportional control valves V1 to V5 controls the supply direction and amount of hydraulic oil supplied to the corresponding hydraulic actuator by electromagnetically driving a spool based on a command signal from the controller 100. This allows the controller 100 to control the operating direction and operating speed of each of the hydraulic actuators described above.

[0039] The controller 100 has a load measuring unit 101 and an operation control unit 102. The load measuring unit 101 measures the load and center of gravity position of the work platform 50 based on voltage signals from the left potentiometer 62L and right potentiometer 62R described above. The operation control unit 102 controls the travel of the aerial work platform 1 and the operation of the boom 30 based on the load and center of gravity position of the work platform 50 measured by the load measuring unit 101 and the outputs of various sensors described below, and also causes the alarm device 70 to output an alarm.

[0040] The various sensors mentioned above include a swing angle sensor 71, a derrick angle sensor 72, an extension amount sensor 73, a swing angle sensor 74, a work platform inclination sensor 75, and a vehicle body inclination sensor 76. The swing angle sensor 71 detects the swing angle of the swing body 20 relative to the running body 10, and outputs a detection value corresponding to the detected swing angle to the controller 100. The derrick angle sensor 72 detects the derrick angle of the boom 30, and outputs a detection value corresponding to the detected derrick angle to the controller 100. The extension amount sensor 73 detects the extension amount of the boom 30 and outputs a detection value corresponding to the detected extension amount to the controller 100. The swing angle sensor 74 detects the swing angle of the work platform 50 and outputs a detection value corresponding to the detected swing angle to the controller 100. The work platform inclination sensor 75 detects the inclination angle of the floor surface of the work platform 50 in the left-right direction relative to the horizontal and outputs a detection value corresponding to the detected inclination angle to the controller 100. The vehicle body inclination sensor 76 detects the forward / backward inclination angle of the aerial work vehicle 1 relative to the horizontal plane and outputs a detection value corresponding to the detected inclination angle to the controller 100.

[0041] Next, a method for measuring the load and center of gravity position of the workbench 50 in the load measuring unit 101 will be described with reference to Figures 8 and 9. Figure 8 is a graph showing the load values ​​measured based on the voltage values ​​of the left potentiometer 62L and the right potentiometer 62R in relation to the load applied to the workbench 50, where (a) is a graph when the load is applied to the left side of the workbench 50, (b) is a graph when the load is applied to the right side of the workbench 50, and (c) is a graph when the load is applied to the center of the workbench 50. (d) is a graph showing the average value of each load measured based on the voltage values ​​of the left potentiometer 62L and the right potentiometer 62R.

[0042] FIG. 9(a) is a schematic plan view of the workbench 50 to explain the position of the load on the workbench 50 when the data for each graph shown in FIGS. 8(a) to 8(c) was acquired. In this figure, the center line CL is the same as the center line CL shown in FIG. 5. FIG. 9(b) is a view of the workbench 50 shown in FIG. 9(a) as seen from the direction of arrow A. Note that the front-rear, left-right, and front-rear directions used in the description with reference to FIG. 9(a) and the up-down, left-right, and front-rear directions used in the description with reference to FIG. 9(b) follow the arrows in each figure, and these directions correspond to the up-down, front-rear, left-right, and front-rear directions shown in FIGS. 1 to 3 and 5.

[0043] The graphs shown in FIGS. 8(a) to 8(c) show the loads measured when the floor surface of the workbench 50 is divided into three equal regions in the left-right direction, as shown in FIG. 9(a), and the regions are designated as "left side," "center," and "right side" in order from left to right, and the load applied to each region is increased. In these graphs, the dashed diagonal lines indicate ideal values ​​where the actual load matches the measured load. As described above, the voltage signals generated by the left potentiometer 62L and the right potentiometer 62R have voltage values ​​corresponding to the vertical displacement of the workbench 50. For this reason, the load measurement unit 101 stores in advance in memory the voltage values ​​of the left potentiometer 62L and the right potentiometer 62R when the value of the load applied to the center line CL of the workbench 50 is changed. As a result, when any load is applied to the workbench 50, the load measuring unit 101 reads out from memory the load value corresponding to the voltage values ​​of the left potentiometer 62L and the right potentiometer 62R at that time, and uses that value as the measured load value.

[0044] Therefore, as shown in FIG. 8(c), when a load is applied to the center of the workbench 50, the load measured based on the voltage values ​​of the left potentiometer 62L and the right potentiometer 62R approximately matches the actual load. In contrast, when a load is applied to the left side of the workbench 50, the torsional load in the direction of arrow α shown in FIG. 9(b) increases as the load increases. This causes a larger downward displacement of the left side of the workbench 50 than when the load is applied to the center, and the voltage value of the left potentiometer 62L also increases. Therefore, as shown in FIG. 8(a), the load measured based on the voltage value of the left potentiometer 62L is larger than the ideal value. Furthermore, due to this torsional load, the downward displacement of the right side of the workbench 50 is slightly smaller than when the load is applied to the center, and as a result, the load measured based on the voltage value of the right potentiometer 62R is slightly smaller than the ideal value.

[0045] On the other hand, when a load is applied to the right side of the workbench 50, the larger the load, the more the load decreases as shown in FIG. As the torsional load in the direction of arrow β increases, the downward displacement of the right side of the workbench 50 increases compared to when a load is applied to the center, and the voltage value of the right potentiometer 62R also increases. As a result, the load measured based on the voltage value of the right potentiometer 62R becomes larger than the ideal value, as shown in Figure 8(b). Furthermore, as a result of this torsional load, the downward displacement of the left side of the workbench 50 becomes smaller compared to when a load is applied to the center, and the load measured based on the voltage value of the left potentiometer 62L becomes smaller than the ideal value.

[0046] Furthermore, as described above, the distance from the center line CL to the left mounting hole BH (see FIG. 4) and the right mounting hole BH of the workbench fixing member 52 is equal to each other. As a result, even if a torsional load is applied to the workbench 50 and a difference occurs between the amount of downward displacement of the left side of the workbench 50 and the amount of downward displacement of the right side of the workbench 50, the deviation from the ideal value can be reduced, as shown in FIG. 8(d), by calculating the average value of the load measured based on the voltage value of the left potentiometer 62L and the load measured based on the voltage value of the right potentiometer 62R.

[0047] Based on the above, the load measurement process executed by the load measurement unit 101 will be described with reference to the flowchart in Fig. 10. Here, the load measurement process shown in Fig. 10 is repeatedly executed at predetermined time intervals (for example, 2 seconds). First, the load measurement unit 101 reads the voltage value of the left potentiometer 62L (step S1), refers to the relationship between the voltage value and the load value stored in advance, and sets the load value corresponding to the read voltage value as the measured value of the left load (step S2). Next, the load measurement unit 101 reads the voltage value of the right potentiometer 62R (step S3), refers to the relationship between the voltage value and the load value stored in advance, and sets the load value corresponding to the read voltage value as the measured value of the right load (step S4). Then, the load measurement unit 101 calculates the average value of the measured value of the left load obtained in step S2 and the measured value of the right load obtained in step S4, and sets this as the measured value of the load applied to the workbench 50 (step S5).

[0048] Next, the load measurement unit 101 determines the position of the center of gravity of the workbench 50. First, the load measurement unit 101 determines whether the measurement value of the left side load obtained in step S2 is greater than the measurement value of the load of the workbench 50 calculated in step S5 by a predetermined value or more (step S6). If the measurement value of the left side load is greater than the measurement value of the load of the workbench 50 by a predetermined value or more, the determination result is YES, and the load measurement unit 101 determines that the position of the center of gravity of the workbench 50 is "left side" as shown in Figure 9(a) (step S7).

[0049] In the determination process of step S6, if the measured value of the left side load is not greater than the measured value of the load of the workbench 50 by a predetermined value or more, the determination result is NO, and then the load measurement unit 101 determines whether the measured value of the right side load obtained in step S4 is greater than the measured value of the load of the workbench 50 calculated in step S5 by a predetermined value or more (step S8). If the measured value of the right side load is greater than the measured value of the load of the workbench 50 by a predetermined value or more, the determination result is YES, and the load measurement unit 101 determines that the position of the center of gravity of the workbench 50 is "right side" as shown in FIG. 9(a) (step S9). On the other hand, if the measured value of the right side load is not greater than the measured value of the load of the workbench 50 by a predetermined value or more, the determination result is NO, and the load measurement unit 101 determines that the position of the center of gravity of the workbench 50 is "center" as shown in FIG. 9(a) (step S10).

[0050] When the load measuring unit 101 determines the position of the center of gravity of the workbench by the processing of step S7, S9 or S10, it acquires the current date and time from the RTC (real-time clock) of the controller 100 and stores the measured value of the load of the workbench 50 calculated in step S5 and the position of the center of gravity of the workbench 50 determined in any of steps S7, S9 or S10 in the memory card 52 (see FIG. 7) set in the operating device 51 (step S11). Then, the load measuring unit 101 waits until it is time to execute the next load measurement process. It becomes a machine state.

[0051] As the load measurement unit 101 repeatedly executes the load measurement process described above, changes in the load and center of gravity position of the work platform 50 while the aerial work platform 1 is in operation are accumulated in the memory card 52. The load and center of gravity position of the work platform 50 accumulated in the memory card 52 can be useful information, for example, when performing maintenance on the aerial work platform 1 or when investigating the cause of a malfunction. That is, by analyzing how much load was loaded at which position on the work platform 50 and for how long, for example, if it is found that a large load was loaded on the left side of the work platform 50 for a long time, efficient work can be performed by carefully checking the consumables used on the boom 30 and the left side of the work platform 50 (for example, a pin that pivots two members) during maintenance.

[0052] Next, the control of the travel of the vehicle for aerial work 1 and the operation of the boom 30 by the operation control unit 102 will be described. Conventionally, there have been systems that control the travel of the vehicle for aerial work 1 and the rotation, elevation and extension of the boom 30 to prevent the vehicle for aerial work 1 from tipping over, based on the tilt angle of the vehicle for aerial work 1, the rotation angle of the rotating body 20, the hoisting angle and extension amount of the boom 30, the load weight of the work platform 50, and the tilt angle of the floor surface. However, these controls did not take into account the position of the center of gravity and the swing angle of the work platform 50, and so the safe operating range of the vehicle for aerial work 1 and the boom 30 was determined assuming the position of the center of gravity and the swing angle of the work platform 50 that would most increase the tipping moment, which resulted in a tendency to restrict the operating range of the boom 30 more than necessary.

[0053] Therefore, in this embodiment, the travel of the vehicle for aerial work 1 and the operating range of the boom 30 are determined taking into consideration the swing angle and center of gravity of the work platform 50 in addition to the load capacity of the work platform 50, thereby expanding the operating range of the boom 30 compared to conventional methods while ensuring safety. For example, in the past, to prevent the vehicle for aerial work 1 from tipping forward, when the load weight of the work platform 50 was a [kg], travel of the vehicle for aerial work 1 was restricted when the boom hoisting angle of the boom 30 was b [deg] or more. In this embodiment, even if the load weight is a [kg], if the center of gravity of the work platform 50 is on the left side and the swing angle of the work platform 50 is 90 [deg] to the right (i.e., the center of gravity of the work platform 50 is shifted to the rear of the vehicle for aerial work 1), travel of the vehicle for aerial work 1 is permitted as long as the boom hoisting angle is c [deg] or less (c > b).

[0054] In this way, by including the swivel angle of the work platform 50 and the position of the center of gravity of the work platform 50 in the conditions that determine the travel of the aerial work vehicle 1 and the operating range of the boom 30, the operating range of the boom 30 can be expanded while maintaining safety, and the boom 30 can be used more effectively to improve workability.

[0055] In this embodiment, the rotary potentiometer 62 and transmission mechanism 61 are used as detectors for detecting the load on the workbench 50, but a linear potentiometer and transmission mechanism may be used instead. Also, in this embodiment, the floor surface of the workbench 50 is divided into three equal regions (left, center, and right) in the left-right direction based on the position of the center of gravity of the workbench 50, but the region may be divided into even smaller regions (for example, five regions) depending on the accuracy of the voltage values ​​of the left and right potentiometers 62 relative to the amount of displacement of the workbench 50 in the up-down direction.

[0056] Furthermore, in this embodiment, the left and right potentiometers 62 and the transmission mechanism 61 are positioned at equal distances from the center line CL as shown in Fig. 5, but if the distances from the center line CL are different on the left and right, one or both of the loads may be corrected when determining the left and right loads in steps S2 and S4 of the load measurement process shown in Fig. 10. In this correction, for example, a correction is made so that the load values ​​are measured at positions at equal distances from the center line CL in a direction perpendicular to the center line CL. More specifically, the distance from the center line CL and the work table Since the amount of displacement of the work table 50 in the vertical direction is approximately proportional (the further away from the center line CL, the greater the amount of displacement of the work table 50), the load may be calculated based on, for example, multiplying the voltage value of one or both of the left and right potentiometers 62 by a predetermined coefficient. Alternatively, the relationship between the load and the voltage value taking into account the predetermined coefficient may be stored, and the load may be calculated based on this. [Explanation of symbols]

[0057] 1. Aerial work platform 30 Boom 40 Parallel link mechanism 41 Boom side vertical member 42 Upper horizontal link member 43 Lower horizontal link member 50 Workbench 52 Workbench fixing member 60 Spring 61 Transmission Mechanism 62 Potentiometer 71 Rotation angle sensor 72 Elevation angle sensor 73 Extension sensor 74 Swing angle sensor 75 Work floor tilt sensor 76 Body tilt sensor 100 Controllers 101 Load measurement unit 102 Operation control unit 610 Crank parts 612 Connecting shaft

Claims

1. A vehicle for working at height is configured by attaching a work platform via a parallel link mechanism to the tip of a boom that is freely raised and lowered on a vehicle body, the parallel link mechanism is composed of a boom-side vertical member pivotally connected to the tip of the boom and extending vertically, an upper horizontal link member whose base end is pivotally connected to the boom-side vertical member and extending horizontally, a work platform-side vertical member pivotally connected to the tip of the upper horizontal link member and extending vertically, to which the work platform is fixed, and a lower horizontal link member positioned below the upper horizontal link member, extending horizontally, with its base end pivotally connected to the boom-side vertical member and its tip end pivotally connected to the work platform-side vertical member, and the work platform is displaceable in the up and down direction relative to the boom-side vertical member, a coil spring attached between the boom-side vertical member and the work platform-side vertical member, the coil spring expanding and contracting in response to the load of the work platform; a plurality of detectors that output detection values ​​corresponding to the vertical displacement of the work table caused by the expansion and contraction of the coil spring; a load measuring device that measures the load on the work platform based on detection values ​​output from the plurality of detectors.

2. The aerial work vehicle described in claim 1, characterized in that the multiple detectors are arranged at positions spaced apart across the displacement plane in a direction perpendicular to the vertical displacement plane of the work platform at the pivot point between the tip of the boom and the boom side vertical member.

3. 3. The vehicle for working at height according to claim 2, wherein the load measuring device performs processing to reduce deviations between the detected values ​​output from the plurality of detectors.

4. The aerial work platform according to claim 3, characterized in that the load measuring device determines the position of the center of gravity when a load is applied to the work platform based on the difference in the magnitude of each detection value output from the plurality of detectors.

5. a plurality of types of sensors for detecting the posture of the aerial work platform; 5. The aerial work platform according to claim 4, further comprising an operation control device that controls the operation of the boom based on the detection values ​​of the plurality of types of sensors, the load of the work platform measured by the load measuring device, and the center of gravity position of the work platform determined by the load measuring device.

6. The detector comprises: a rotary potentiometer having a rotary shaft and outputting an electrical signal corresponding to the rotation angle of the rotary shaft; a crank member having one end fixed to the rotary shaft of the potentiometer; A high-altitude work vehicle as described in any one of claims 1 to 5, characterized in that it is composed of a connecting member having one end rotatably attached to the other end of the crank member and the other end rotatably attached to the work platform side vertical member.

Images