Safety device of high lift work vehicle

Abstract

To provide a safety device for a high lift work vehicle capable of restricting and releasing the movement of a work platform without compromising safety.SOLUTION: If a release switch is operated to an operating position before a detected separation distance DK detected by a distance sensor 55 becomes less than a predetermined set distance DS, a safety device restricts the movement of a work platform 40 when the detected separation distance DK becomes less than the set distance DS, and when a specified release operation is performed on the operating lever and release switch after the restriction has been imposed, releases the restriction, allowing the movement of the work platform 40 even in a situation where the detected separation distance DK becomes less than the set distance DS.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a safety device for a high-altitude work vehicle equipped with a work platform for a worker to ride on. [Background technology]

[0002] One type of high-altitude work vehicle known in the art is equipped with a boom that is mounted on a mobile body and can rotate, rise and fall, and extend / retract, and a work platform for the worker mounted on the tip of the boom, in which the worker on the work platform operates an operating device provided on the work platform to activate the boom, thereby allowing the work platform to be moved to any desired high-altitude position. Such vehicles are used for a variety of high-altitude work tasks, such as electric wire construction, building and ship construction, and highway construction.

[0003] In such aerial work vehicles, a distance sensor such as a laser sensor or an ultrasonic sensor is provided on the side of the work platform to detect the distance between the work platform and an object (obstacle) that exists in the direction of movement of the work platform, and when this detected distance (detected distance) becomes equal to or less than a preset distance, the movement of the work platform is forcibly restricted and stopped (restricted stop) (see, for example, Patent Document 1). With such a configuration, it is possible to prevent the work platform from coming into contact with an obstacle without the worker noticing it.

[0004] Also, in such aerial work vehicles that restrict the movement of the work platform, there is known a device that is provided with a release switch for releasing the restriction on the movement of the work platform on the work platform, and when the worker operates this release switch, the restriction on the movement of the work platform is released, and the work platform can be brought closer to the obstacle to within a set distance (for example, see Patent Document 2). With such a configuration, by releasing the restriction on the movement of the work platform, it becomes possible to bring the work platform closer to the obstacle, so that the work platform can be brought close enough to the work target that is near the obstacle to perform the work. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Publication No. 8-10594 [Patent Document 2] JP 2013-52948 A Summary of the Invention [Problem to be solved by the invention]

[0006] The restriction on the movement of the work platform is usually released when the movement of the work platform is restricted, but the restriction may be released when the movement of the work platform is not restricted. For example, the restriction may be released when the movement of the work platform is not restricted by the operator operating the release switch before the work platform approaches the obstacle to a set distance or less. In a conventional aerial work vehicle, when the restriction is released when the movement of the work platform is not restricted, the movement of the work platform is not restricted even if the work platform approaches the obstacle to a set distance or less, and the movement is allowed as it is. Therefore, there is a possibility that the operator may move the work platform and contact the obstacle without noticing that the work platform is approaching the obstacle while the movement of the work platform is not restricted, which may cause a safety problem.

[0007] The present invention has been made in consideration of such problems, and aims to provide a safety device for a high-altitude work vehicle that can restrict and release the movement of the work platform without compromising safety. [Means for solving the problem]

[0008] In order to solve the above problems, the safety device for a high-altitude work vehicle according to the present invention includes a traveling body capable of traveling, a lifting device (e.g., a rotating body 20 and a boom 30 in the embodiments) provided on the traveling body, a work platform that is raised and lowered by the lifting device, a traveling operation unit (e.g., a traveling operation lever 51a and a steering operation lever 51b in the embodiments) that is operated to travel and move the traveling body, a lifting operation unit (e.g., a swing operation lever 51c, a hoisting operation lever 51d, a telescopic operation lever 51e and a swing operation lever 51f in the embodiments) that is operated to operate the lifting device to raise and lower the work platform, a distance detection unit (e.g., a distance sensor 55 in the embodiments) provided on the work platform to detect a separation distance from a surrounding object, and a detection unit that detects the traveling and movement of the traveling body when the separation distance detected by the distance detection unit becomes equal to or less than a preset distance. and a movement restriction unit (for example, an operation control unit 61 and a movement restriction control unit 63 in the embodiments) that restricts at least one of the operations of the lifting device to restrict the movement of the work platform, and a restriction release unit (for example, a release switch 52, an operation control unit 61 and a restriction release control unit 64 in the embodiments) that releases the restriction to allow the work platform to move when the movement of the work platform is restricted by the movement restriction unit, and when the restriction release unit releases the restriction in a state where the movement restriction unit is not performing the restriction (for example, when the release switch 52 in the embodiments is started to be operated before the movement is restricted and the restriction release operation signal from the release switch 52 starts to be output before the movement is restricted), the movement of the work platform is restricted when the separation distance becomes equal to or less than the set distance, and the restriction is released when a predetermined release operation for releasing the restriction is performed.

[0009] In the safety device for a high-altitude work vehicle having the above-described configuration, it is preferable that the specified release operation is an operation of at least one of the operating units of the travel operation unit, the lifting operation unit, and the restriction release unit (e.g., release switch 52 in the embodiment).

[0010] Furthermore, in the safety device for a high-altitude work vehicle having the above-described configuration, it is preferable that the specified release operation is an operation of returning at least one of the travel operating unit and the lifting operating unit to a neutral position and an operation of returning the operating unit of the deregulation unit, which has been operated to an operating position, to the neutral position once and then back to the operating position again. Effect of the Invention

[0011] According to the safety device for a high-altitude work vehicle of the present invention, even when the restriction release section releases the restriction when the movement of the work platform is not being restricted by the movement restriction section, the movement of the work platform is restricted when the separation distance detected by the distance detection section becomes less than or equal to the set distance, and the restriction is released when a specified release operation is performed to release the restriction, so that it is possible to restrict and release the movement of the work platform without compromising safety. [Brief description of the drawings]

[0012] [Figure 1] 1 is a side view showing a vehicle for working at height equipped with a safety device according to the present invention. [Diagram 2] FIG. 2 is a block diagram showing the safety device. [Diagram 3] 4 is a side view showing a detectable range of a distance sensor in the safety device. FIG. [Figure 4] 5A and 5B are diagrams for explaining a set distance applied in the safety device. [Diagram 5] 11A and 11B are diagrams for explaining the operation of the safety device (when operation of the release switch is started before the movement is restricted). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a self-propelled vehicle 1 for working at height equipped with a safety device according to one embodiment of the present invention. The overall configuration of the vehicle for high altitude work 1 will be described with reference to FIG.

[0014] The vehicle for working at height 1 comprises a travelling body (vehicle body) 10 having a pair of left and right front wheels 12 and rear wheels 13 and capable of travelling, a rotating body 20 mounted on the travelling body 10 so as to be capable of horizontally rotating, a boom 30 mounted on the upper part of the rotating body 20 so as to be swingable, and a work platform 40 for a worker mounted on the tip of the boom 30. Hereinafter, the left direction in Fig. 1 will be referred to as the forward direction (forward direction), and the right direction in Fig. 1 will be referred to as the backward direction (rear direction). The rotating body 20 and the boom 30 form a lifting device.

[0015] The running body 10 is provided with a running motor 14 for driving the front wheels, and the running body 10 is configured to run by rotating the left and right front wheels (also called "driving wheels") 12 by the rotation of this running motor 14. The running motor 14 is provided with a brake cylinder 15 for braking the rotation of the left and right front wheels 12, respectively. The brake cylinder 15 is a so-called negative brake that mechanically brakes and locks the rotating shaft of the running motor 14 by the force of a built-in spring when hydraulic oil is not supplied. In addition, the running body 10 is provided with a steering cylinder 16, and the running body 10 can be steered (the rear wheels 13 can be steered) by expanding and contracting this steering cylinder 16 to change the direction (steering angle) of the left and right rear wheels (also called "steering wheels") 13 via a steering mechanism (not shown). The running device of the running body 10 is composed of the front wheels 12, the rear wheels 13, the running motor 14, the brake cylinder 15, the steering cylinder 16, the steering mechanism, etc.

[0016] A swivel mechanism 11 is provided between the running body 10 and the rotating body 20. The swivel mechanism 11 is configured to include an outer wheel (not shown) provided on the upper part of the running body 10 and an inner wheel (not shown) provided on the lower part of the rotating body 20 and engaged with the outer wheel. The rotating body 20 is attached to the running body 10 via the swivel mechanism 11 so as to be horizontally rotatable, and is configured to be horizontally rotatable 360 ​​degrees around a vertical axis by rotating a swivel motor 21 provided in the running body 10. Note that, although not shown, a swivel joint that enables the supply of hydraulic oil between the running body 10 side and the rotating body 20 side (connection of hydraulic piping) and a slip ring that enables input and output of signals and power between the running body 10 side and the rotating body 20 side (connection of electrical wiring) are attached to the inside of the swivel mechanism 11.

[0017] The boom 30 has a configuration in which, from the rotating body 20 side, a base end boom 31, an intermediate boom 32, and a tip end boom 33 are nested together, and the boom 30 can be extended and retracted in the axial direction (longitudinal direction) by the extension and retraction of a telescopic cylinder 34 provided inside. In addition, a derricking cylinder 22 is straddled between the rotating body 20 and the boom 30, and by extending and retracting this derricking cylinder 22, the entire boom 30 can be raised and lowered in the vertical plane around the foot pin 23.

[0018] A vertical post 37 is pivotally supported at the tip of the boom 30 so as to be swingable up and down. The swing of the vertical post 37 is controlled by a leveling mechanism (not shown) disposed between the vertical post 37 and the tip of the tip boom 33, so that the vertical post 37 is always held in a vertical position regardless of the hoisting angle of the boom 30. A work platform 40 for an operator to sit on is attached to the vertical post 37 via a work platform bracket 39. A swivel motor 38 is attached inside the work platform bracket 39, and the entire work platform 40 can be swung (horizontally rotated) around the vertical post 37 by rotating the swivel motor 38. Here, the vertical post 37 is always held in a vertical position as described above, so that the floor surface of the work platform 40 is always held horizontal regardless of the hoisting angle of the boom 30.

[0019] An operating device 50 is attached to the work platform 40 and is operated by a worker standing on the work platform. 2, the operation device 50 has a travel operation lever 51a for operating the travel body 10 (starting, stopping, and speed adjustment during travel), a steering operation lever 51b for steering the travel body 10 (steering the steering wheel 13), a rotation operation lever 51c for rotating the rotating body 20, a hoisting operation lever 51d for raising and lowering the boom 30, a telescopic operation lever 51e for telescopically extending the boom 30, and a swing operation lever 51f for swinging the work platform 40. These operation levers 51a to 51f are automatically returned to a neutral position and become in a non-operated state when the operation levers 51a to 51f are released, and are configured so that they can be tilted in a direction determined for each operation lever 51a to 51f based on the neutral position.

[0020] The operation state (operation direction and operation amount based on the neutral position) of each of the operation levers 51a to 51f is detected by an operation detector such as a potentiometer, and the detection signal is input to a controller 60 described later as an operation signal corresponding to the operation state of each of the operation levers 51a to 51f. In this way, a worker on the work platform 40 can operate each of the operation levers 51a to 51f of the operating device 50 to perform operations such as traveling movement of the traveling body 10 (rotational movement of the traveling motor 14), braking of the traveling body 10 (retraction and extension of the brake cylinder 15), steering of the traveling body 10 (retraction and extension of the steering cylinder 16), swinging movement of the revolving body 20 (rotational movement of the swing motor 21), raising and lowering of the boom 30 (retraction and extension of the raising and lowering cylinder 22), extending and retracting of the boom 30 (retraction and extension of the telescopic cylinder 34), and swinging movement of the work platform 40 (rotational movement of the swing motor 38).

[0021] As shown in FIG. 2, the operating mechanism of the aerial work vehicle 1 comprises a controller 60 which receives an operation signal from the operating device 50 and controls the travel motor 14, brake cylinder 15, steering cylinder 16, swing motor 21, hoisting cylinder 22, telescopic cylinder 34, swing motor 38, etc. (hereinafter these are also referred to as "hydraulic actuators"), and a hydraulic unit 70 which supplies hydraulic oil to drive these hydraulic actuators.

[0022] The hydraulic unit 70 is configured to include a hydraulic tank 71 that stores hydraulic oil, a hydraulic pump 72 that is driven by the power of the engine E mounted on the swing body 20 to discharge hydraulic oil, and a control valve unit 73 that controls the supply direction and supply amount of hydraulic oil supplied from the hydraulic pump 72 to each hydraulic actuator. The control valve unit 73 includes a travel control valve V1 corresponding to the travel motor 14, a brake control valve V2 corresponding to the brake cylinder 15, a steering control valve V3 corresponding to the steering cylinder 16, a swing control valve V4 corresponding to the swing motor 21, a hoisting control valve V5 corresponding to the hoisting cylinder 22, a telescopic control valve V6 corresponding to the telescopic cylinder 34, and a swing control valve V7 corresponding to the swing motor 38. Based on a command signal from an operation control unit 61 (described in detail later) of the controller 60, the control valve unit 73 electromagnetically drives the spools of each of the control valves V1 to V7 to control the supply direction and supply amount of hydraulic oil supplied from the hydraulic pump 72 to each hydraulic actuator, thereby controlling the drive direction and drive speed of each hydraulic actuator. When an operation signal is input from each of the operating levers 51a-51f, the operation control section 61 of the controller 60 outputs a command signal corresponding to this operation signal (operation direction and operation amount) to the corresponding control valves V1-V7, and drives the hydraulic actuator in the drive direction and drive speed corresponding to this operation signal. The operation amount of the operating levers 51a-51f and the output value of the operation signal are approximately proportional to each other, and the output value of this operation signal and the output value of the command signal to the control valves V1-V7 (valve opening, i.e., the amount of hydraulic oil supplied to the hydraulic actuator) are also approximately proportional to each other.

[0023] Although not shown, a pedal-type foot switch is provided on the floor of the workbench 40, which is operated by a worker standing on the workbench 40 by stepping on it with his foot. This foot switch is a switch that enables the operation of each hydraulic actuator by operating each of the operating levers 51a to 51f only when it is stepped on, and outputs a signal (also referred to as a "foot switch operation signal") when the worker is stepping on it with his foot (operating state), and when the worker releases the foot, In the state where the foot switch is depressed (non-operated state), the switch operation signal is not output. The foot switch operation signal output from this foot switch is input to the controller 60, and the operation control section 61 of the controller 60 treats the operation signal output from each of the operation levers 51a to 51f as valid only when the foot switch operation signal is output from the foot switch. Therefore, even if the worker on the work platform 40 operates each of the operation levers 51a to 51f, the operation is not valid unless the foot switch is depressed, so the worker must first depress the foot switch before operating each of the operation levers 51a to 51f. Therefore, for the sake of convenience, in the following description, it is assumed that the foot switch is always depressed when each of the operation levers 51a to 51f is operated, and the description thereof will be omitted.

[0024] Next, a safety device according to one embodiment of the present invention will be described with reference mainly to FIGS.

[0025] 2, the safety device of this embodiment is mainly composed of operation levers 51a to 51f, a release switch 52, a distance sensor 55, a controller 60, and a control valve unit 73. This safety device has a movement restriction function that detects the separation distance between the work platform 40 and an object (obstacle S) present around the work platform 40 and restricts the movement of the work platform 40 to prevent interference with the obstacle S, and a restriction release function that releases the restriction on the movement. Note that the control valve unit 73 has been described above, so a repeated explanation will be omitted.

[0026] The release switch 52 (for example, composed of a button-type momentary switch) is provided on the operating device 50, and outputs a signal (also referred to as a "restriction release operation signal") to the controller 60 only while it is operated to an operating position (for example, a position where the release switch 52 is pressed in) by a worker on the workbench 40. Furthermore, when the hand is released from the release switch 52, the release switch 52 automatically returns from the operating position to the neutral position and enters a non-operated state. In this non-operated state, the release switch 52 does not output a restriction release operation signal.

[0027] As shown in FIG. 3, the distance sensor 55 is attached to the rear end side of the work platform 40 (opposite side of the operating device 50) and detects the distance from the obstacle S present behind the work platform 40 every moment. The distance sensor 55 is, for example, configured with LiDAR (abbreviation of Light Detection and Ranging or Laser Imaging Detection and Ranging). This distance sensor 55 detects the distance to the obstacle S (distance measurement point) based on the round trip time until the irradiated laser light reaches the obstacle S (distance measurement point) and returns. In addition, this distance sensor 55 detects the distance to the obstacle S (distance measurement point) three-dimensionally within a detectable range 56 of a predetermined angle in the up-down and left-right directions by scanning the laser light two-dimensionally in the vertical and horizontal directions at high speed. Note that the distance sensor 55 is attached to the rear side of the work platform 40, and the distance from the obstacle S detected by the distance sensor 55 can be substantially regarded as the distance between the work platform 40 and the obstacle S. The distance sensor 55 detects the distance to an obstacle S present within the detectable range 56 from moment to moment, and outputs a detection signal according to the detected distance (detected distance DK shown in FIG. 4) to the controller 60.

[0028] In this embodiment, the distance sensor 55 is provided on the rear end side of the work table 40, but it may be provided on the front, rear, left and right, top and bottom of the work table 40 (two or more distance sensors 55 may be provided). The distance sensor 55 is not limited to LiDAR, and other non-contact distance sensors such as ultrasonic sensors, infrared sensors, and radar sensors (millimeter wave radar) may be used. Instead of the distance sensor 55, an imaging device such as a monocular camera, a stereo camera, or a depth camera may be used.

[0029] The controller 60 has an operation control unit 61 , a distance setting unit 62 , a movement restriction control unit 63 , and a restriction release control unit 64 .

[0030] The operation control unit 61 outputs command signals (control signals) to each control valve V1 to V7 in response to the operation signals from each operating lever 51a to 51f, and electromagnetically drives the spools of each control valve V1 to V7, thereby controlling the driving direction and driving speed of each hydraulic actuator, and thereby controlling the movement of the worktable 40.

[0031] When the travel operation lever 51a is tilted forward from the neutral position (front / back / left / right directions based on the operating operator: the same applies below), the movement direction of the spool and the valve opening of the travel control valve V1 are controlled so that the traveling body 10 travels in a direction (forward direction) and speed (traveling speed) corresponding to the operation direction and amount of operation, thereby controlling the drive direction and drive speed of the travel motor 14. On the other hand, when the travel operation lever 51a is tilted backward from the neutral position, the movement direction of the spool and the valve opening of the travel control valve V1 are controlled so that the traveling body 10 travels in a direction (reverse direction) and speed (traveling speed) corresponding to the operation direction and amount of operation, thereby controlling the drive direction and drive speed of the travel motor 14.

[0032] Furthermore, when the travel operation lever 51a is tilted in either the forward or backward direction from the neutral position, the brake control valve V2 is controlled to an excited state and hydraulic oil is supplied to the brake cylinder 15, thereby releasing the braking of the front wheel 12 by the brake cylinder 15 and allowing the rotation of the front wheel 12. On the other hand, when the travel operation lever 51a is in the neutral position (a state in which the lever has returned to the neutral position), the brake control valve V2 is controlled to a non-excited state and the supply of hydraulic oil to the brake cylinder 15 is cut off, thereby braking the rotation of the front wheel 12.

[0033] When the steering operation lever 51b is tilted leftward from the neutral position, the movement direction of the spool and the valve opening of the steering control valve V3 are controlled to control the drive direction and drive speed of the steering cylinder 16 so that the rear wheels 13 are steered in a direction (leftward with respect to the traveling direction) and in a rotation amount (steering angle) corresponding to the operation direction and amount. On the other hand, when the steering operation lever 51b is operated rightward from the neutral position, the movement direction of the spool and the valve opening of the steering control valve V3 are controlled to control the drive direction and drive speed of the steering cylinder 16 so that the rear wheels 13 are steered in a direction (rightward with respect to the traveling direction) and in a rotation amount (steering angle) corresponding to the operation direction and amount.

[0034] When the swing operation lever 51c is tilted leftward from the neutral position, the movement direction of the spool and the valve opening of the swing control valve V4 are controlled so that the swing body 20 swings in a direction (left direction) and speed (swing speed) corresponding to the operation direction and amount, thereby controlling the drive direction and drive speed of the swing motor 21. On the other hand, when the swing operation lever 51c is tilted rightward from the neutral position, the movement direction of the spool and the valve opening of the swing control valve V4 are controlled so that the swing body 20 swings in a direction (right direction) and speed (swing speed) corresponding to the operation direction and amount.

[0035] When the hoisting operation lever 51d is tilted forward from the neutral position, the movement direction of the spool and valve opening of the hoisting control valve V5 are controlled so that the boom 30 is raised or lowered in a direction (raising direction) and speed (raising speed) corresponding to the operation direction and amount, thereby controlling the drive direction and drive speed of the hoisting cylinder 22. On the other hand, when the hoisting operation lever 51d is tilted backward from the neutral position, the movement direction of the spool and valve opening of the hoisting control valve V5 are controlled so that the boom 30 is lowered in a direction (lowering direction) and speed (lowering speed) corresponding to the operation direction and amount.

[0036] When the telescopic operating lever 51e is tilted forward from the neutral position, the movement direction of the spool and the valve opening of the telescopic control valve V6 are controlled so that the boom 30 retracts in a direction (retraction direction) and at a speed (retraction speed) corresponding to the operation direction and amount of the operation, thereby controlling the drive direction and drive speed of the telescopic cylinder 34. On the other hand, when the telescopic operating lever 51e is tilted backward from the neutral position, the movement direction of the spool and the valve opening of the telescopic control valve V6 are controlled so that the boom 30 extends in a direction (extension direction) and at a speed (extension speed) corresponding to the operation direction and amount of the operation, thereby controlling the drive direction and drive speed of the telescopic cylinder 34.

[0037] When the swing operation lever 51f is tilted leftward from the neutral position, the movement direction of the spool and the valve opening of the swing control valve V7 are controlled to control the drive direction and drive speed of the swing motor 38 so that the worktable 40 swings in a direction (left-handed direction) and at a speed (swing speed) corresponding to the operation direction and amount of the operation. On the other hand, when the swing operation lever 51f is tilted rightward from the neutral position, the movement direction of the spool and the valve opening of the swing control valve V7 are controlled to control the drive direction and drive speed of the swing motor 38 so that the worktable 40 swings in a direction (right-handed direction) and at a speed (swing speed) corresponding to the operation direction and amount of the operation.

[0038] 4, the distance setting unit 62 sets a set distance DS, which is a threshold value for determining whether or not to restrict and stop the movement of the work platform 40. The set distance DS is set as a distance at which the work platform 40 can be stopped in front of the obstacle S with sufficient margin. Note that as the set distance DS, a set distance when the traveling body 10 is traveling, a set distance when the revolving body 20 and the boom 30 are revolving, a set distance when the boom 30 is rising and falling or extending and contracting, a set distance when the work platform 40 is swinging, etc. may be provided, and each of these may be set to a different value.

[0039] The movement restriction control unit 63 compares the detected separation distance DK detected by the distance sensor 55 with the set distance DS set by the distance setting unit 62 to determine whether the work platform 40 has approached the obstacle S to within the set distance DS. When the movement restriction control unit 63 determines that the detected separation distance DK has become equal to or less than the set distance DS, it determines that the work platform 40 has approached the obstacle S to within the set distance DS, and outputs a movement restriction signal in the controller 60 (mainly to the operation control unit 61) to restrict the movement of the work platform 40. This movement restriction signal is continuously output during the period when the detected separation distance DK is equal to or less than the set distance DS, and is stopped from being output when the detected separation distance DK is not equal to or less than the set distance DS. When a movement restriction signal is output from the movement restriction control unit 63 (excluding the case where a restriction release signal described later is output from the restriction release control unit 64), the operation control unit 61 forcibly controls the spools of the control valves V1 to V7 regardless of the operation signal from each of the operation levers 51a to 51f (the operation state (operated position and direction) of each of the operation levers 51a to 51f), and performs movement restriction to restrict and stop the movement of the work platform 40 by decelerating the hydraulic actuator being driven until it stops. This movement restriction of the work platform 40 may be a sudden stop of the work platform 40 or a gentle stop of the work platform 40. Note that the term "movement of the work platform 40" is used to include a case where the position of the work platform 40 (position relative to the traveling body 10 and the ground) moves in response to the rotation, elevation, and extension of the boom 30 and the swinging of the work platform 40, and a case where the position of the work platform 40 (position relative to the ground) moves in response to the traveling movement of the traveling body 10.

[0040] The restriction release control unit 64 outputs a restriction release signal for releasing the restriction on the movement of the workbench 40 in the controller 60 (mainly to the operation control unit 61) in response to a restriction release operation signal output from the release switch 52 when the release switch 52 is operated to the operation position. When a restriction release signal is output from the restriction release control unit 64, the operation control unit 61 The movement of the workbench 40 is controlled by releasing the restriction on the movement of the workbench 40 and controlling the spools of the control valves V1 to V7 according to the operation state of each of the operating levers 51a to 51f. This makes it possible to move the workbench 40 even in a situation where the separation distance DK detected by the distance sensor 55 is equal to or less than the set distance DS. Note that when the restriction on the movement of the workbench 40 is released and the workbench 40 is moved in a direction approaching the obstacle S, the workbench 40 may be controlled to move at a speed slower than the normal speed (a speed corresponding to the operation state of each of the operating levers 51a to 51f).

[0041] The release switch 52 is basically operated to release the restriction on movement of the work platform 40 when the detected separation distance DK becomes equal to or less than the set distance DS and the movement of the work platform 40 is restricted. When the release switch 52 is operated from the neutral position to the operating position after the movement of the work platform 40 is restricted and a restriction release operation signal is output from the release switch 52, a restriction release signal is output from the restriction release control unit 64, and the restriction on the movement of the work platform 40 is released during the period in which the restriction release signal is being output.

[0042] On the other hand, there is a case (hereinafter also referred to as "specific case") where the release switch 52 is operated to the operation position and the release switch 52 starts to output a restriction release operation signal before the detected separation distance DK becomes equal to or less than the set distance DS (a state in which the movement of the work platform 40 is not restricted). In this specific case, the restriction release control unit 64 judges the restriction release operation signal to be invalid even if it is output from the release switch 52, and does not output the restriction release signal. Then, when the detected separation distance DK becomes equal to or less than the set distance DS while the restriction release operation signal is being output from the release switch 52, the movement restriction control unit 63 outputs a movement restriction signal, and the movement of the work platform 40 is restricted. Also, when the restriction release operation signal from the release switch 52, which started to be output before the movement restriction is performed, continues to be output after the movement restriction is started, the restriction release control unit 64 still judges the restriction release operation signal to be invalid, does not output the restriction release signal, and the movement restriction continues. In order to release the movement restriction, a predetermined release operation needs to be performed. In this embodiment, the predetermined release operation is defined as an operation of returning each of the operating levers 51a to 51f to the neutral position and an operation of returning the release switch 52, which has been operated to the operating position, to the neutral position once and then back to the operating position again, but it can be set arbitrarily. For example, a release operation member (which may be a lever type, a button type, or another type) separate from the release switch 52 may be provided, and operating this release operation member to a predetermined position may be set as the predetermined release operation. When the predetermined release operation is performed, a restriction release signal is output from the restriction release control unit 64, and the restriction on movement of the workbench 40 is released.

[0043] Next, the operation of the safety device in the above-mentioned specific case will be described with additional reference to FIG. 5. FIG. 5 illustrates a case where the work platform 40 moves horizontally and approaches an obstacle S due to the telescopic movement (extension) of the boom 30 or the traveling movement of the traveling body 10. "Operation lever ON" in FIG. 5 indicates that at least one of the operation levers 51a to 51f is operated, and "operation lever OFF" indicates that all of the operation levers 51a to 51f are returned to the neutral position. Also, "release switch ON" in FIG. 5 means that the release switch 52 is operated to the operating position, and "release switch OFF" indicates that the release switch 52 is returned to the neutral position. In the following description, for convenience, the operation levers 51a to 51f are collectively referred to as "operation lever 51."

[0044] 5(A) illustrates a case where the detected separation distance DK detected by the distance sensor 55 is greater than the set distance DS set by the distance setting unit 62. It also illustrates a case where the operating lever 51 is operated in a direction to bring the work platform 40 closer to the obstacle S (operating lever ON), and the release switch 52 is operated from the neutral position to the operating position (release switch ON). In this case, an operation signal is output from the operating lever 51, and a restriction release operation signal is output from the release switch 52. At this time, the movement restriction control unit 63 By comparing the detected separation distance DK with the set distance DS, it is determined that the work platform 40 is not closer to the obstacle S than the set distance DS, and a movement restriction signal is not output to the operation control unit 61. In addition, the restriction release control unit 64 determines that the restriction release operation signal from the release switch 52 is invalid, and does not output a restriction release signal. As a result, the movement of the work platform 40 is not restricted, and the operation control unit 61 controls the movement of the work platform 40 in response to the operation signal from the operation lever 51.

[0045] FIG. 5B illustrates the case when the detected separation distance DK becomes equal to or smaller than the set distance DS. At this time, the operation lever 51 is operated in a direction to move the work platform 40 closer to the obstacle S (operation lever ON), and the release switch 52 is operated to the operation position (release switch ON), and the state continues. In this case, an operation signal is output from the operation lever 51, and a restriction release operation signal is output from the release switch 52. At this time, the movement restriction control unit 63 compares the detected separation distance DK with the set distance DS, determines that the work platform 40 has approached the obstacle S to the extent that it is equal to or smaller than the set distance DS, and outputs a movement restriction signal. In addition, the restriction release control unit 64 determines that the restriction release operation signal from the release switch 52 is invalid, and does not output a restriction release signal. As a result, the operation control unit 61 performs movement restriction to restrict and stop the movement of the work platform 40 regardless of the operation signal from the operation lever 51.

[0046] 5B also shows a case where the operation lever 51 is returned to the neutral position (operation lever OFF) after the movement of the work platform 40 is restricted, and the release switch 52 is once returned to the neutral position (release switch OFF) and then operated to the operation position again (release switch ON) (a predetermined release operation is performed). In this case, no operation signal is output from the operation lever 51, and the release switch 52 once stops outputting the restriction release operation signal and then outputs the restriction release operation signal again. At this time, the restriction release control unit 64 judges that the restriction release operation signal from the release switch 52 is valid and outputs a restriction release signal. As a result, the restriction on the movement of the work platform 40 is released, and the movement of the work platform 40 (including the movement of the work platform 40 in the direction approaching the obstacle S) is permitted in a situation where the detected separation distance DK is equal to or less than the set distance DS.

[0047] FIG. 5(C) shows a case where the operation lever 51 is operated from the neutral position (operation lever OFF) to the operation position (here, the operation position is assumed to be the operation position in the direction in which the work platform 40 approaches the obstacle S) (operation lever ON) after the movement restriction of the work platform 40 is released. The release switch 52 is maintained in the operated state at the operation position. In this case, an operation signal is output from the operation lever 51, and a restriction release operation signal is output from the release switch 52. In addition, a restriction release signal is output from the restriction release control unit 64 upon receiving the restriction release operation signal from the release switch 52. At this time, the operation control unit 61 can control the movement of the work platform 40 in response to the operation signal from the operation lever 51, and thus the work platform 40 can be moved in the direction approaching the obstacle S even in a situation in which the detection separation distance DK is equal to or less than the set distance DS. In addition, by operating the operation lever 51 while paying sufficient attention, the worker can move the work platform 40 as close as possible to the obstacle S.

[0048] As described above, according to the safety device of this embodiment, even if the release switch 52 is operated to the operating position before the detection separation distance DK becomes equal to or less than the set distance DS, the movement of the work platform 40 is restricted when the detection separation distance DK becomes equal to or less than the set distance DS. Therefore, the possibility that the work platform 40 contacts the obstacle S without the worker noticing that the work platform 40 is approaching the obstacle S can be reduced, so safety is high. In addition, in order to release the movement restriction of the work platform 40 in this case, the worker needs to perform a predetermined release operation on the operation lever 51 and the release switch 52, so that the movement restriction of the work platform 40 is not released unintentionally by the worker, and the work platform 40 does not move unexpectedly. Therefore, it is possible to ensure safety when releasing the movement restriction of the work platform 40.

[0049] The present invention is not limited to the above-described embodiments, and can be appropriately improved without departing from the gist of the present invention. For example, in the above-described embodiment, the separation distance from the obstacle S existing behind the workbench 40 is detected, but it may be configured to detect the separation distance from the obstacle S existing above the workbench 40. That is, at a work site such as indoors of a building or inside a tunnel, when the workbench 40 is moved upward, the separation distance from the obstacle S existing above the workbench 40 is detected, and when the detected separation distance DK becomes less than or equal to the set distance DS, the workbench 40 may be configured to be regulated and stopped. Even in that case, the configuration of the above-described embodiment can be applied.

[0050] Further, in the above-described embodiment, for example, an alarm device composed of an alarm lamp, an alarm buzzer, a display monitor, a voice speaker, etc. may be provided on the workbench 40 or the like, and when the detected separation distance DK becomes less than or equal to the set distance DS and the movement of the workbench 40 is restricted, an alarm may be issued from the alarm device to arouse the attention of the operator.

[0051] Further, in the above-described embodiment, when the movement restriction of the workbench 40 is released, the movement of the workbench 40 is allowed even in a situation where the detected separation distance DK is less than or equal to the set distance DS, and the workbench 40 can be brought close to the obstacle S as close as possible. However, when the workbench 40 approaches the obstacle S to a predetermined distance (<DS), it may be configured such that the workbench 40 cannot be moved further in the direction approaching the obstacle S.

[0052] Further, in the above-described embodiment, as the aerial work vehicle according to the present invention, a self-propelled aerial work vehicle is exemplified and described, but it is not limited thereto, and for example, it may be applied to other aerial work vehicles such as a truck-mounted aerial work vehicle. Further, in the above-described embodiment, a wheeled aerial work vehicle is exemplified and described, but it is not limited thereto, and a crawler-type aerial work vehicle may be used.

Explanation of Reference Numerals

[0053] 1 Aerial work vehicle 10 Traveling body 20 Rotating body 30 Boom 40 Workbench 52 Release switch 55 Distance Sensor 60 Controller 73 Control valve section DS setting distance DK Detection Distance

Claims

1. A movable traveling body; A lifting device provided on the traveling body; A workbench that is raised and lowered by the lifting device; A travel operation unit that is operated to travel and move the travel body; A lifting operation unit that is operated to activate the lifting device and lift and move the work platform; a distance detection unit provided on the workbench and detecting a distance between the workbench and a surrounding object; a movement restriction unit that restricts at least one of the traveling movement of the traveling body and the operation of the lifting device to restrict the movement of the work platform when the separation distance detected by the distance detection unit becomes equal to or less than a preset distance; a restriction release unit that, when the movement of the work platform is restricted by the movement restriction unit, releases the restriction to allow the work platform to move, A safety device for a high-altitude work vehicle, characterized in that when the restriction release section releases the restriction while the movement restriction section is not performing the restriction, the device restricts the movement of the work platform when the separation distance becomes less than the set distance, and releases the restriction when a specified release operation is performed to release the restriction.

2. 2. The safety device for a vehicle for working at height according to claim 1, wherein the predetermined release operation is an operation of at least one of the operation units of the travel operation unit, the lift operation unit, and the restriction release unit.

3. The safety device for a high-altitude work vehicle as described in claim 2, characterized in that the specified release operation is an operation to return at least one of the travel operating unit and the lifting operating unit to a neutral position and an operation to return the operating unit of the deregulation unit, which has been operated to an operating position, to the neutral position once and then to the operating position again.

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