JP2002060198A - Safety device for high lift work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety device for a high lift work vehicle preventing overload on aerial platform-derricking cylinders of the high lift vehicle and preventing the bending of a boom. SOLUTION: This safety device for the high lift work vehicle having an upper structure turnably provided on a lower structure, the telescopic boom 5 provided in the upper structure such that the boom 5 can be freely derricked, and an aerial platform provided at the tip of the boom 5 such that the aerial platform can be freely derricked by a pair of the aerial platform-derricking cylinders 12 has an aerial platform-derricking cylinder axial force detection means 30A detecting axial force of the cylinders 12, an alarm means 30C and a controller 21. The controller 21 operates the alarm means 30C to give an alarm when the axial force of the cylinders 12 obtained from the detection means 30A exceeds a prescribed value, or when moment applied to the boom 5 obtained from the detection means 30A exceeds a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a safety device for an aerial work vehicle.

[0002]

2. Description of the Related Art Conventionally, as a safety device for preventing a fall from occurring when an overload is applied to an aerial work vehicle having a workbench at the tip of a boom equipped to extend and retract on a vehicle body, for example, And JP-B-61-47799 are known. According to the safety device described in Japanese Patent Publication No. 61-47999, when the pressure of the boom raising / lowering cylinder reaches a set value, the pressure switch is activated, and the operation of the boom is stopped, thereby preventing the boom from falling down. Things.

However, as shown in FIG. 1, when the work platform 8 of the aerial work vehicle 1 is freely raised and lowered by the work platform hoisting cylinder 12, the work platform 8 of the aerial work vehicle 1 is not provided.
In addition, when a heavy object is placed as shown in FIG. 5, the pressure of the up-and-down cylinder 6 may exceed the allowable cylinder load of the work-table up-and-down cylinder 12 even if the pressure does not exceed the set value.
As shown in FIG. 5, when the heavy object 50 is placed at a position off the center of the work table 8 on the work table 8 of the aerial work vehicle 1, the pressure of the undulating cylinder 6 does not exceed the set value. However, if the up-and-down direction of the boom 5 is the front-back direction, the eccentric moment applied to the boom 5 in the left-right direction, which is different from that, becomes large, and the boom 5 overturns and the boom 5 is bent in the left-right direction. Force will be applied. As described above, when the cylinder load exceeds the allowable load of the worktable raising / lowering cylinder 12 or when an eccentric moment is applied to the boom 5 in the left-right direction, the above-mentioned Japanese Patent Publication No. 61-4779 is used.
The safety device described in No. 9 cannot cope.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is intended to prevent an overload of a worktable raising / lowering cylinder of an aerial work vehicle and to prevent a boom from being bent. It is intended to provide a safety device for a work vehicle.

[0005]

In order to achieve the above object, a first aspect of the present invention is to provide a lower traveling body provided with an upper revolving body so as to be able to pivot, and a telescopic boom that can be raised and lowered. A work platform hoist cylinder axial force for detecting an axial force of the work table hoist cylinder in a safety device for an aerial work vehicle provided on an upper revolving structure and having a work table movable up and down by a work table hoist cylinder at the end of the boom. A detecting means, an alarming means, and a controller, wherein the controller activates the alarming means when the axial force of the worktable hoisting cylinder determined by the worktable hoisting cylinder axial force detecting means exceeds a predetermined value. The alarm is issued.

According to the first aspect of the present invention, the controller constantly monitors the axial force generated in the worktable raising and lowering cylinder for raising and lowering the worktable, compares the axial force with the allowable axial force, and when the allowable axial force is exceeded, Since the warning means was activated,
The worktable hoist cylinder can be protected from being damaged or causing oil leakage, the work of the aerial work vehicle can be performed safely, and the durability of the worktable hoist cylinder can be improved.

According to a second aspect of the present invention, an upper revolving structure is provided on a lower traveling body so as to be revolvable, a telescopic boom is provided on the upper revolving body so as to be able to be raised and lowered, and a tip of the boom is raised and lowered by a pair of worktable raising and lowering cylinders. In a safety device for an aerial work vehicle provided with a free work platform, the work platform raising / lowering cylinder axial force detecting means for detecting the axial force of the pair of work platform raising / lowering cylinders, an alarm means, and a controller, The controller is configured to activate the alarm unit and issue an alarm when the moment applied to the boom obtained by the platform up-and-down cylinder axial force detecting unit exceeds a predetermined value.

According to the second aspect of the present invention, the controller determines the axial force applied to each of the pair of worktable hoisting cylinders by the pressure of the pair of worktable hoisting cylinders, and obtains the eccentric moment applied to the boom by the axial force. When the moment exceeds a predetermined value, the warning means is activated, so that the boom of the aerial work vehicle can be protected from being damaged or deformed, and the work on the aerial work vehicle can be performed safely. Can also improve the durability of the aerial work vehicle boom

According to a third aspect of the present invention, in the first or second aspect, there is provided a boom hoisting cylinder axial force detecting means for detecting an axial force of a boom hoisting cylinder for raising and lowering the boom, and the controller is provided with the boom hoisting cylinder. When the axial force of the boom raising / lowering cylinder obtained by the axial force detecting means exceeds a predetermined value, the alarm means is activated to generate an alarm.

According to the third aspect of the present invention, in addition to the first or second aspect, the axial force generated in the boom hoist cylinder is constantly monitored by the controller and compared with the allowable axial force. In this case, the alarm means is activated, so that the boom hoist cylinder can be protected from damage or oil leakage, and the work of the aerial work platform can be performed safely. The durability of the boom hoist cylinder can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a working posture state of the aerial work vehicle. As shown in FIG. 1, an aerial platform vehicle 1 has an upper revolving unit 4 having a driver's cab 3 mounted on a lower traveling unit 2 so as to be horizontally rotatable around a vertical axis.
Has a telescopic multi-stage boom 5 pivotally mounted at its base end so as to be able to move up and down. The upper swing body 4 swings by a hydraulic motor (not shown). The boom 5 is raised and lowered by a boom raising and lowering cylinder 6. In the working posture, the outriggers 7 protrude from both sides of the lower traveling body 2 to stably support the high-altitude work 1.

The work table 8 is pivotally attached to a bracket 11 at the tip of the boom 5 via a turning device 9 so as to be able to move up and down. A worktable hoist cylinder 12 is mounted between the hoist bracket 10 and the tip bracket 11.

FIG. 2 is a detailed view showing how the worktable 8 is attached to the tip of the boom 5. FIG. 3 is a diagram viewed from Z in FIG.
The worktable 8 has a turning device 9 mounted on the lower surface thereof.
Can be turned around the vertical axis. The turning device 9 is attached to an up-and-down bracket 10, and one end of the up-and-down bracket 10 is rotatably attached to the tip bracket 11 by a pin 10a.

At the other end of the up / down bracket 10, a rod end of a worktable up / down cylinder 12 is rotatably attached by a pin 10b. The cylinder portion of the worktable up / down cylinder 12 is rotatably attached to the tip bracket 11 by a trunnion 12a. The worktable 8 can be raised and lowered by extending and retracting the worktable lifting cylinder 12 with a hydraulic device (not shown). As shown in FIG. 3, a plurality of work platform hoist cylinders 12 are provided on the left and right sides of the tip bracket 11, and in this case, two work platform hoist cylinders 12R are provided. I have.

Next, FIG. 4 shows a system configuration of a safety device for an aerial work vehicle according to the present invention. A right platform up / down cylinder head pressure sensor 31R is provided on the head side of the right platform up / down cylinder 12R, and a right platform up / down cylinder bottom pressure sensor 32R is provided on the bottom side, and a head side of the left platform up / down cylinder 12L. Is provided with a left worktable up / down cylinder head pressure sensor 31L, and a left worktable up / down cylinder bottom pressure sensor 32L is provided on the bottom side. A boom hoist cylinder head pressure sensor 33 is provided on the head side of the boom hoist cylinder 6, and a boom hoist cylinder bottom pressure sensor 34 is provided on the bottom side. A boom length sensor 22 for detecting the length of expansion and contraction of the boom 5 and a boom angle sensor 23 for detecting an elevation angle of the boom 5 are provided at positions (not shown) of the boom 5.

The worktable 8 is provided with a warning means 3 at a position (not shown).
As 0C, an alarm buzzer 24 and an alarm lamp 25 are provided, respectively. The controller 21 includes: a right platform up / down cylinder head pressure sensor 31R; a right platform up / down cylinder bottom pressure sensor 32L on the bottom side; a left platform up / down cylinder head pressure sensor 31L; and a left platform up / down cylinder bottom pressure sensor. 32L, a predetermined arithmetic processing described later is performed by an arithmetic processing unit 21A based on signals of the boom undulating cylinder head pressure sensor 33, the boom undulating cylinder bottom pressure sensor 34, the boom length sensor 22, and the boom angle sensor 23, The determination unit 21B makes a determination based on the result, and activates the alarm buzzer 24 and the alarm lamp 25, respectively. The warning means 30C may be installed in the driver's cab 3 or the work site of the aerial work vehicle 1.

As described above, the platform up-and-down cylinder axial force detecting means 30A detects the right platform up-down cylinder head pressure sensor 31R, the right platform up-down cylinder bottom pressure sensor 32R, and the left platform up-down cylinder head pressure. Sensor 3
1L and the left worktable up / down cylinder bottom pressure sensor 32
L, and an arithmetic processing unit 21A of the controller.
The arithmetic processing section 21A performs arithmetic processing based on signals from the sensors to detect the axial force of the worktable hoisting cylinder 12. Further, as described above, the boom hoist cylinder axial force detecting means 30B includes the boom hoist cylinder head pressure sensor 33 and the boom hoist cylinder bottom pressure sensor 34.
And an arithmetic processing unit 21A of the controller. The arithmetic processing unit 21A performs arithmetic processing based on signals from the sensors to detect the axial force of the boom hoist cylinder.

Next, the calculation processing procedure of the controller 21 will be described. FIG. 5 is a schematic diagram showing a state where a heavy object 50 is placed on the work table 8 shown in FIG. As shown in FIG. 5, when a heavy object 50, for example, a generator unit, a rock drill, a small hydraulic shovel, a hydraulic unit, a pneumatic unit, or the like used for work is placed on one side of the work table 8, the right work table The right platform up / down cylinder axial force FR is applied to the up / down cylinder 12R, and the left platform up / down cylinder axial force F is applied to the left platform up / down cylinder 12L.
L is added. The right platform up / down cylinder axial pressure FR is detected by the right platform up / down cylinder head pressure sensor 31R and the right platform up / down cylinder bottom pressure sensor 32R detected by the right platform up / down cylinder bottom pressure sensor 32R. From pressure PRB, FR = PRH × S
It is obtained by calculating the expression of RH-PRB × SRB by the arithmetic processing unit 21A. Here, SRH is the head-side area of the right worktable up / down cylinder 12R, and SRB is the bottom-side area of the right worktable up / down cylinder 12R. Further, the left platform up / down cylinder axis force FL is detected by the left platform up / down cylinder head pressure sensor 31L and the left platform up / down cylinder bottom pressure sensor 32L and detected by the left platform up / down cylinder bottom pressure sensor 32L. FL = PLH × SLH−PLB × SL from cylinder bottom pressure PLB
It is obtained by calculating the expression of B by the arithmetic processing unit 21A. Here, SLH is the area on the head side of the left worktable up / down cylinder 12L, and SLB is the bottom area of the left worktable up / down cylinder 12L.

Work platform undulating cylinder axial force detecting means 30A
And the boom undulating cylinder axial force detecting means 30B,
As an example, the axial force is calculated by the arithmetic processing unit 21A of the controller 21 based on the pressure signal of the cylinder pressure sensor. However, the axial force of the cylinder is directly controlled by the distortion of the rod part of the cylinder or the distortion of the pin of the rod. A sensor that can detect a force may be used.

Each of the right platform up-and-down cylinder axial force FR and the left platform up-and-down cylinder axial force FL obtained as described above is stored in the storage unit 21C of the controller 21 as a predetermined value in advance. The allowable work force is compared with the determination unit 21C, and the axial force F
R, or when the left platform up / down cylinder axial force FL exceeds the platform up / down cylinder axial force allowable value, the alarm buzzer 24 and the alarm lamp 25 are sent from the controller 21.
Is generated, and the alarm means 30C, the alarm buzzer 24 and the alarm lamp 25 operate to notify the worker of the abnormality. Here, the alarm buzzer 24 and the alarm lamp 25 may be operated independently, or may be operated simultaneously.

The right platform up / down cylinder head pressure PRH detected by the right platform up / down cylinder head pressure sensor 31R as a substitute for the platform up / down cylinder axial force.
Right platform up / down cylinder bottom pressure sensor 32R detected by right platform up / down cylinder bottom pressure sensor 32R, left platform up / down cylinder head pressure PLH detected by left platform up / down cylinder head pressure sensor 31L, left platform up / down cylinder bottom. The determination unit 21C compares each of the left worktable up-and-down cylinder bottom pressures PLB detected by the pressure sensor 32L with each allowable pressure value stored in advance in the storage unit 21C of the controller 21 as a predetermined value. If either exceeds the pressure tolerance,
A signal for operating the alarm buzzer 24 and the alarm lamp 25 is generated from the controller 21, and the alarm means 30C, the alarm buzzer 24 and the alarm lamp 25 are operated to notify the worker of the abnormality. good. Here, the alarm buzzer 24 and the alarm lamp 25 may be operated independently, or may be operated simultaneously.

As described above, when the heavy object 50 is eccentrically placed on the work table 8 on one side, the eccentric moment M acts on the boom 5 and the boom 5 is bent. The eccentric moment M is L1, the distance from the longitudinal center of the boom 5 to the longitudinal center of the right platform up / down cylinder 12R, based on the right platform up / down cylinder axial force FR and the left platform up / down cylinder axial force FL. Assuming that the distance from the longitudinal center of No. 5 to the longitudinal center of the left workbench lifting / lowering cylinder 12L is L2, it can be obtained by calculating the formula of M = (FR × L1−FL × L2). The controller 21 obtains the eccentric moment M applied to the boom 5 by the above equation in the arithmetic processing section 21A, and stores the eccentric moment M in the storage section 21C of the controller 21.
When the eccentric moment M exceeds the limit moment ML, the controller 21 sends the alarm buzzer 24 and the alarm lamp 25 to each other. Is generated, and the alarm means 30C, the alarm buzzer 24 and the alarm lamp 25 operate to notify the worker of the abnormality. Here, the alarm buzzer 24 and the alarm lamp 25 may be operated independently, or may be operated simultaneously.

The limit moment ML is, for example, as shown in the graph of FIG.
(In the case of a four-stage boom, one-stage boom length, two-stage boom length, three-stage boom length, and four-stage boom length) are stored in the storage unit 21C of the controller 21 as data. If the boom length does not exist in the data, the limit moment can be obtained by interpolation. The limit moment ML may store a numerical value as a table. Further, the limit moment ML may be a single predetermined value instead of a value corresponding to the up-down angle of the boom 5 and the boom length of the boom 5.

Further, the boom up / down cylinder head pressure PKH detected by the boom up / down cylinder head pressure sensor 33 and the boom up / down cylinder bottom pressure PKB detected by the boom up / down cylinder bottom pressure sensor 34 of the boom up / down cylinder 6 are used to raise and lower the boom. Cylinder axial force FK
Is obtained by calculating the equation of FK = PKH × SKH−PKB × SKB by the calculation processing unit 21A. here,
SKH is the area on the head side of the boom hoist cylinder 6, SKB
Is the bottom area of the boom hoist cylinder 6. The obtained boom hoisting cylinder axial force FK is compared with an allowable value of boom hoisting cylinder axial force stored in advance as a predetermined value in the controller 21, and the boom hoisting cylinder axial force exceeds the boom hoisting cylinder axial force allowable value. The alarm buzzer 24 and the alarm lamp 25
Is generated, and the alarm means 30C, the alarm buzzer 24 and the alarm lamp 25 operate to notify the worker of the abnormality. Here, the alarm buzzer 24 and the alarm lamp 25 may be operated independently, or may be operated simultaneously.

As a substitute for the boom hoist cylinder axial force, the boom hoist cylinder head pressure PKH detected by the boom hoist cylinder head pressure sensor 33 of the boom hoist cylinder 6 and the boom hoist cylinder bottom pressure sensor 34 are detected. The boom hoisting cylinder bottom pressure PKB is compared with a boom hoisting cylinder head pressure allowable value and a boom hoisting cylinder bottom pressure allowable value stored in advance as a predetermined value in the controller 21, respectively.
Alternatively, if the bottom pressure of the boom hoist cylinder exceeds the corresponding allowable value, the controller 21 generates a signal for operating the alarm buzzer 24 and the alarm lamp 25, and the alarm means 30C is provided. The alarm buzzer 24 and the alarm lamp 25 may be operated to notify the worker of the abnormality.

As described above, according to the safety device for an aerial work vehicle according to the present invention, the axial force generated in the worktable up / down cylinder for raising and lowering the worktable is constantly monitored by the controller and compared with the allowable axial force. However, when the allowable axial force is exceeded, the warning means is activated, so that the workbench up / down cylinder can be protected from damage or oil leakage, and the work platform can be safely secured. Work can be performed, and the durability of the worktable undulating cylinder can be improved.

Further, the controller determines the axial force applied to each of the pair of platform lifting cylinders by the pressure of the pair of platform lifting cylinders, determines the eccentric moment applied to the boom by the axial force, and sets the eccentric moment to a predetermined value. When it exceeds, the warning means is activated, so that the boom of the aerial work vehicle can be protected from being damaged or deformed, and the work of the aerial work vehicle can be safely performed. The durability of the boom of the aerial work vehicle can be improved.

Further, the axial force generated in the boom raising / lowering cylinder is constantly monitored by the controller and compared with the allowable axial force. If the allowable axial force is exceeded, the alarm means is activated. The up-and-down cylinder can be protected from being damaged or causing oil leakage, the work of the aerial work vehicle can be performed safely, and the durability of the boom-up / down cylinder can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing a working posture state of an aerial work vehicle.

FIG. 2 is a detailed view of attachment of a worktable to a boom tip.

FIG. 3 is a view as viewed from Z in FIG. 2;

FIG. 4 is a system configuration diagram of a safety device for an aerial work vehicle according to the present invention.

FIG. 5 is a schematic diagram showing a state in which a heavy object is placed on a work table.

FIG. 6 is a graph showing a limit moment.

[Explanation of symbols]

5: Boom, 6: Boom hoist cylinder, 12: Workbench hoist cylinder, 21: Controller, 30A: Workbench hoist cylinder axial force detecting means, 30B: Boom hoist cylinder axial force detecting means, 30C: Alarm means.

Claims (3)

[Claims] An upper revolving structure is provided on a lower traveling structure so as to be revolvable, a telescopic boom is provided on the upper revolving structure so as to be able to move up and down, and a work table which is able to move up and down by a work table raising and lowering cylinder is provided at a tip of the boom. In the safety device of the work platform aerial work platform, a platform lifting cylinder axial force detection means (30A) for detecting the axial force of the platform lifting cylinder (12), an alarm means (30C),
A controller (21), wherein the controller (21) is configured to perform the above-mentioned operation when the axial force of the platform up-and-down cylinder (12) obtained by the platform up-down cylinder axial force detecting means (30A) exceeds a predetermined value. A safety device for an aerial work vehicle, which activates an alarm means (30C) to issue an alarm. 2. A worktable which is provided with an upper revolving structure so as to be pivotable on a lower traveling body, a telescopic boom is provided on the upper revolving structure so as to be able to move up and down, and a pair of worktable raising and lowering cylinders are provided at a tip of the boom. In a safety device for an aerial work vehicle provided with a work platform hoist cylinder axial force detecting means (30A) for detecting the axial force of the pair of work platform hoist cylinders (12), and an alarm means (30
C) and a controller (21), wherein the controller
(21) is characterized in that when the moment applied to the boom (5) obtained by the platform up-and-down cylinder axial force detecting means (3OA) exceeds a predetermined value, the alarm means (30C) is activated to generate an alarm. And safety equipment for aerial work vehicles. 3. A safety device for an aerial work vehicle according to claim 2, wherein a boom hoist cylinder axial force detecting means (30B) detects an axial force of a boom hoist cylinder (6) for raising and lowering the boom (5). The controller (21) activates the alarm means (30C) when the axial force of the boom hoist cylinder (6) obtained by the boom hoist cylinder axial force detecting means (30B) exceeds a predetermined value. A safety device for aerial work vehicles, which is activated to generate an alarm.