JP2004203574A - Stress detector for aerial work vehicles - Google Patents

Abstract

An object of the present invention is to improve the accuracy of fatigue determination.
A stress detection device is incorporated in a boom operation control device for controlling the operation of boom actuators. The stress detection device 60 includes a strain gauge 61 attached to the base of the swivel, and an elapsed time signal generation circuit 69 that outputs an elapsed time signal at a predetermined interval from at least one of the driving of the vehicle and the operation of the boom. When an elapsed time signal is received from the elapsed time signal generation circuit 69, a stress value that captures the stress value calculated by the stress calculation circuit 71 according to the detection value from the strain gauge 61 when the elapsed time signal is received. A work table calculated by the position calculating circuit 49 in accordance with the capture circuit 73 and the elapsed time signal and the stress value correspondingly captured by the stress value capture circuit 73 and the detection value from the work table position sensor 41; And a memory 75 for storing the position in association with the elapsed time signal.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stress detection device for an aerial work vehicle, and more particularly, to a traveling body configured to be able to travel, a boom provided at least to be able to move up and down on the traveling body, and a boom provided at a tip end of the boom. And a stress detection device for an aerial work vehicle, comprising:
[0002]
[Prior art]
The aerial work vehicle that performs aerial work includes, for example, a swivel that is swingably provided on a traveling body that is configured to be able to travel, a boom that is vertically swingably mounted on the swivel, and a boom. And a worktable attached to the tip of the worktable so as to swing up and down. Such an aerial work vehicle moves to the work site by traveling of the traveling body, and can operate the boom and the swivel base to move the work base to a desired position.
[0003]
Here, the work table is loaded with the load of the worker and the work, but these loads often become fluctuating loads and act on the swivel base via the boom. Has been designed in consideration of a situation in which fatigue occurs with a smaller load than in the case of a static load. For example, in the state where the boom extends in the horizontal direction, a large load acts on the base of the swivel (hereinafter, referred to as “weakest part”). It is designed so that the weakest part does not break even when the number of repetitions given is given. By designing in consideration of the fluctuating load, the life of the swivel base can be improved. An apparatus disclosed in Japanese Patent Application Laid-Open Publication No. HEI 10-163556, for example, performs the durability determination in consideration of the fatigue.
[0004]
Further, since the fluctuating load acting on the work table also acts on the boom and the traveling body, the boom and the traveling body are designed in consideration of fatigue as in the case of the swivel table.
[0005]
Here, in order to determine the degree of fatigue of the swivel, the boom, and the traveling body, it is necessary to know the stress applied to the component whose fatigue is to be determined and the number of repetitions of the stress (hereinafter referred to as the number of stress repetitions). is there. For this reason, the work contents are heard from the work vehicle using the aerial work vehicle, and the operating time of the boom and the running time of the traveling body are obtained from the hour meter.
[0006]
[Patent Document 1] Japanese Utility Model Registration No. 3066993
[Problems to be solved by the invention]
However, the content of the report from the operator may not always match the actual use state of the boom, and a problem arises in that the accuracy of the fatigue determination is reduced.
[0008]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a stress detection device for an aerial work vehicle capable of performing accurate fatigue determination.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a stress detection device for an aerial work vehicle according to the present invention is provided with a traveling body (for example, a vehicle body 3 in the embodiment) configured to be able to travel, and provided at least on the traveling body so as to be able to move up and down. And a workbench provided at the tip of the boom, the device for detecting the stress of an aerial work vehicle, provided at one or more places of the aerial work vehicle. And a time signal output means (e.g., a strain gauge 61 in the embodiment) that outputs an elapsed time signal at predetermined intervals from the time of running motion or boom operation by the running body. When the elapsed time signal is received from the elapsed time signal generation circuit 69) and the time signal output means, the response detected by the stress detection means when the elapsed time signal is received is received. Stress value capturing means (for example, the stress value capturing circuit 73 in the embodiment) for capturing a value, and storage means (for example, for storing the elapsed time signal and the stress value correspondingly captured by the stress value capturing means, for example) , The memory 75 in the embodiment).
[0010]
According to the stress detection device having the above-described configuration, the stress detection means is provided at any one or a plurality of locations of the aerial work vehicle, and the stress value from the stress detection means is used when the traveling body moves or the boom operates. By storing the elapsed time for each elapsed time together with the elapsed time, it is possible to accurately obtain the stress value acting on the place where the stress detecting means is provided and the elapsed time. Therefore, by determining the relationship between the number of times the stress has acted and the stress value from the stress value and the elapsed time, it is possible to accurately determine the fatigue at the location where the stress detecting means is provided.
[0011]
Further, the stress detection device having the above-described configuration includes a boom operation control unit (for example, the boom operation control device 40 in the embodiment) for controlling the operation of the boom, and the boom operation control unit detects a position of the workbench with respect to the traveling body. Work table position detecting means (for example, the work table position sensor 41 in the embodiment) for storing the elapsed time signal and the stress value and the elapsed time signal correspondingly taken by the stress value taking means. Correspondingly, the work table position detected by the work table position detecting means may be stored.
[0012]
According to the stress detection device having the above configuration, the storage means stores the worktable position corresponding to the elapsed time signal from the worktable position detection means, so that the number of times of the stress operation and the stress value are determined based on the relationship between the stress value and the elapsed time. When the relationship is obtained, the number of times the stress is applied can be set to a number that matches the actual situation in consideration of the worktable position. Therefore, it is possible to more accurately determine the fatigue of the member provided with the stress detecting means.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. This embodiment shows an aspect of an aerial work vehicle having a work table at the tip of a boom configured to be extendable and contractible. First, before describing the stress detection device according to the present invention, an aerial work vehicle equipped with the stress detection device will be described. As shown in FIG. 1, the aerial work vehicle 1 is configured based on a truck vehicle, and is capable of traveling with a pair of front wheels 5 and rear wheels 7 disposed at front, rear, left and right ends of a vehicle body 3. Is provided with an operating cabin 9 at the front. In the driving cabin 9, there are disposed parking rakes P for bringing the rear wheels 7 into a braking state, and jacks 11 for lifting and supporting the vehicle body 3 are provided on both front and rear left and right sides of the vehicle body 3. A swivel table 13 is attached to the front central portion of the vehicle body 3 on the rear side of the driving cabin 9 and is configured to be rotatable by a swivel motor 15 built in the vehicle body 3. The base of the boom 20 is pivotally connected to the swivel base 13 so as to be able to move up and down. The boom 20 can be moved up and down by an up and down cylinder 21.
[0014]
The boom 20 is telescopically movable by combining a plurality of boom members in a telescopic manner, and is movable by a built-in telescopic cylinder 23. A work table 25 is pivotally connected to the tip of the boom 20 so as to be able to swing up and down. The work table 25 is supported by a leveling device 29 in a horizontal state regardless of the up-and-down angle of the boom 20. The workbench 25 is provided with a boom operating device 31 for operating the turning motion, the undulating motion, and the telescopic motion of the boom 20. The boom 20 is stored in the vehicle in a state where the boom 20 is folded down from the front side to the rear side in a fully contracted state.
[0015]
In the driving cabin 9, the driving force of an engine (not shown) is taken out to drive a swing motor 15, an up-and-down cylinder 21, and a telescopic cylinder 23 (hereinafter, these are collectively referred to as “boom actuators 15, 21, 23”). A PTO switch (PTO SW33) for operating the drive of a PTO mechanism (not shown) for driving a hydraulic pump (not shown), which is a source, is provided.
[0016]
As shown in FIG. 2, a boom operation control device 40 that controls the operation of the boom actuators 15, 21, and 23 is mounted on the aerial work vehicle 1 configured as described above. The boom operation control device 40 includes a boom operation device 31, a workbench position sensor 41, and a vehicle controller 45. The boom operating device 31 includes an operating lever 31a shown in FIG. 1 which is configured to be tiltable. When the operating lever 31a is tilted in the front-rear and left-right directions, the turning operation of the turning motor 15 via the vehicle controller 45, The telescopic operation and the telescopic operation of the telescopic cylinder 23 can be operated. The worktable position sensor 41 includes a turning angle sensor (not shown) that detects the turning angle of the turning table 13 shown in FIG. 1 and an up / down angle sensor (see FIG. 1) that detects the turning angle of the boom 20 shown in FIG. 1) and an extension sensor (not shown) for detecting the extension amount of the boom 20 shown in FIG.
[0017]
The vehicle controller 45 includes an operation control circuit 47 that controls the operation of each of the operation control valves V that controls each operation of the boom actuators 15, 21, and 23 in accordance with an operation signal from the boom operation device 31; A position calculating circuit 49 that calculates the position of the worktable 25 shown in FIG. 1 according to the detection values from the sensors 41 (a turning angle sensor, an elevation angle sensor, and an extension sensor), and a worktable position calculated by the position calculation circuit 49 Determination circuit 51 for determining whether or not exceeds a predetermined allowable movement area (not shown) in which the worktable 25 can move, and the position of the worktable 25 exceeds the allowable movement area by the movement determination circuit 51. When it is determined that the operation of the boom actuators 15, 21, and 23 is stopped, the transmission of the operation control signal from the operation control circuit 47 to the operation control valve V is interrupted. It is configured to include a working inhibition circuit 53 win. The movement determination circuit 51 determines whether a moment value from a moment sensor (not shown) for detecting a moment acting on the vehicle body 3 via the boom 20 shown in FIG. May be activated when it is determined that the moment exceeds the allowable moment.
[0018]
The boom operation control device 40 configured as described above incorporates a stress detection device 60 having a stress detection function of detecting a stress applied to any part of the vehicle and performing storage of the stress to determine fatigue. . The stress detection device 60 includes a strain gauge 61, a brake operation detection sensor 63, a PTO SW 33, and a stress detection unit 67 built in the vehicle controller 45. The strain gauge 61 is attached to the weakest portion of the base 13 a of the swivel base 13, and is operated by the load acting on the swivel base 13 by the operation of the boom 20 and the load acting on the swivel base 13 by moving the boom 20 up and down by running the vehicle. The resulting distortion of the base 13a is detected. The brake operation detection sensor 63 is a sensor that detects that the parking brake P shown in FIG. 1 is in the operating state, that is, that the rear wheel 7 is in the braking state. Since the PTO SW 33 has been described above, its description is omitted.
[0019]
The stress detection section 67 includes an elapsed time signal generation circuit 69, a stress calculation circuit 71, a stress value acquisition circuit 73, and a memory 75. The elapsed time signal generation circuit 69 is provided to output a non-operation signal from the brake operation detection sensor 63 indicating that the parking brake P shown in FIG. 1 is in the non-operation state, or to operate the PTO SW 33 to extract the driving force of an engine (not shown). It has a function of operating when receiving an ON signal and generating a time signal at predetermined intervals, and the predetermined interval can be arbitrarily adjusted. The stress calculating circuit 71 has a function of calculating the stress acting on the base 13a of the swivel base 13 shown in FIG. 1 according to the detection value from the strain gauge. Each time the elapsed time signal is received from the elapsed time signal generation circuit 69, the stress value acquisition circuit 73 has a function of acquiring the stress value calculated by the stress operation circuit 71 when receiving the elapsed time signal. The memory 75 stores the elapsed time tn, the stress value captured by the stress value capturing circuit corresponding to the elapsed time tn, and the worktable position corresponding to the elapsed time tn from the position calculation circuit 49. That is, the memory stores the elapsed times t1, t2,... Tn shown in FIG. 3, the corresponding stress values σn, and the worktable position.
[0020]
Now, when the vehicle is moving, the boom operation control device 40, which also has the stress detection device 60 configured as described above, operates as shown in FIG. 2 so that the parking brake P shown in FIG. Therefore, when the vehicle is moved to the work site and the work is being performed by the boom 20 shown in FIG. 1, an ON signal is output from the PTO SW 33. . For this reason, when there is a possibility that a fluctuating load may act on the base 13a of the swivel base 13 shown in FIG. 1, the stress detecting device 60 operates to generate an elapsed time signal. The stress value acquisition circuit 73 acquires the stress value calculated by the stress operation circuit 71 for each elapsed time signal, and stores the elapsed times t1, t2,... Tn shown in FIG. .sigma.1, .sigma.2... .sigma.n and the worktable position are stored. Note that the workbench position is calculated by the position calculation circuit 49 according to the detection value from the workbench position sensor 41 and stored in the memory 75 together with the elapsed time.
[0021]
Therefore, most of the stress generated in the base portion 13a of the swivel base 13 shown in FIG. 1 due to the fluctuating load can be stored in the memory 75.
[0022]
Subsequently, a description will be given of the life determination of the members constituting the base 13a of the swivel base 13 shown in FIG. 1 based on the data stored in the memory 75. FIG. 4 shows the fatigue characteristics of the members constituting the base 13a of the swivel base 13, and is a so-called SN curve in which the ordinate represents the stress amplitude S and the abscissa represents the number of stress repetitions N. As shown in FIG. 4, when the stress falls below a certain value, no matter how much load is applied, no break occurs and the SN curve becomes horizontal. Since it is considered that this horizontal portion does not break forever below this stress, the limit stress value at which this curve becomes horizontal is generally called the fatigue limit. Further, in the slope of the SN curve, the number of repetitions up to the fracture corresponding to the stress exceeding the fatigue limit can be estimated by the SN curve.
[0023]
Therefore, in determining the life of the member forming the base 13a of the swivel base 13 shown in FIG. 1, first, the number of repetitions N leading to breakage is estimated by an SN curve. For example, when a stress σ1 and a stress σ2 are generated by a fluctuating load acting on the base 13a of the turntable 13, the stress repetition times N estimated from the SN curves corresponding to these stresses are N1 and N2, respectively. . Subsequently, the ratio of the number of stress repetitions actually applied to the member of the base 13a to the number N of stress repetitions is determined. Then, the life of the member is determined based on whether or not this value exceeds a predetermined value. Here, as described above, when the load acting on the member fluctuates and two types of stresses σ1 and σ2 are generated, the life is determined by Expression 1 called the linear damage law.
[0024]
(Equation 1)
n1 / N1 + n2 / N2 = C
[0025]
Here, n1 is the number of times the stress σ1 has occurred, N1 is the number of stress repetitions corresponding to σ1 on the SN curve, n2 is the number of times the stress σ2 has occurred, and N2 is the number of times the stress σ2 has occurred. Is the number of stress repetitions corresponding to σ2, where C is a constant and usually C = 1. That is, it means that the member is broken when n1 / N1 + n2 / N2 = 1.
[0026]
The number of times n1 at which the stress σ1 has occurred and the number of times n2 at which the stress σ2 has occurred are counted based on the data stored in the memory 75 shown in FIG. In the data stored in the memory 75, as shown in FIG. 3, the stress σ is stored together with the elapsed time t. This data is read into the personal computer 80 or the like shown in FIG. 2 and the number of times n1, n2 is counted. Here, for example, when counting the number of times n2, as indicated by an arrow A in FIG. 3, when each stress σ2 of the adjacent elapsed time t is constant, it corresponds to the elapsed time t from the position calculation circuit 49 shown in FIG. The position information of the work table 25 shown in FIG. That is, if the stress value and the workbench position information are the same, the number of stress repetitions during this elapsed time is counted as one instead of four. This is because there is no load change during this elapsed time, and the generated stress is only once. The number n1 is counted in the same manner as the case of the number n2. For this reason, the stress repetition times n1 and n2 are numbers that match the actual conditions.
[0027]
Subsequently, the personal computer 80 shown in FIG. 2 performs an arithmetic operation by substituting N1 and N2 estimated from the SN curve shown in FIG. The value thus obtained is compared with 1. Then, the personal computer 80 determines that the base 13a of the swivel base 13 has a fatigue life if the calculated value exceeds 1, and determines that it is in a usable state if the calculated value is smaller than 1. The determination of fatigue by the personal computer 80 is performed according to a program set in the personal computer 80, and the contents of the program can be changed. That is, the value of the constant C in Equation 1 may be appropriately changed and set, or the fatigue life may be calculated based on a fatigue damage rule different from the linear damage law. As the fatigue damage law, various rules have been conventionally proposed, such as a modification of the straight line damage law, and these are well-known. Therefore, description of the fatigue life calculation based on these is omitted.
[0028]
In this manner, in a state in which a fluctuating load acts on the base 13a of the swivel base 13 shown in FIG. 1, all the stresses generated in the base 13a are stored in the memory 75 shown in FIG. Further, since the number of times of stress repetition n1 and n2 is counted as a number corresponding to the actual condition, the life can be determined accurately.
[0029]
In the above-described embodiment, the strain gauge 61 is attached to the base 13a of the swivel base 13. However, the present invention is not limited to this location, and may be attached to any location of the aerial work vehicle 1.
[0030]
【The invention's effect】
As described above, according to the aerial work vehicle stress detection device of the present invention, the aerial work vehicle is provided with the stress detecting means at any one or a plurality of locations, and travels the stress value from the stress detecting means. By storing the elapsed time from the time of the movement of the body or the operation of the boom together with the elapsed time for each elapsed time, it is possible to accurately obtain the stress value and the elapsed time acting on the place where the stress detecting means is provided. Therefore, by determining the relationship between the number of times the stress has acted and the stress value from the stress value and the elapsed time, it is possible to accurately determine the fatigue at the location where the stress detecting means is provided.
[Brief description of the drawings]
FIG. 1 is a front view of an aerial work vehicle equipped with a stress detection device according to an embodiment of the present invention.
FIG. 2 shows a block diagram of a stress detection device according to one embodiment of the present invention.
FIG. 3 shows data stored in a memory of the stress detection device according to one embodiment of the present invention.
FIG. 4 shows an SN curve used at the time of fatigue determination in one embodiment of the present invention.
[Explanation of symbols]
1 aerial work platform 3 body (running body)
20 boom 25 work table 40 boom operation control device (boom operation control means)
41 Workbench position sensor (workbench position detection means)
60 stress detection device 61 strain gauge (stress detection means)
69 Elapsed time signal generation circuit (time signal output means)
73 Stress value acquisition circuit (Stress value acquisition means)
75 memory (storage means)

Claims (2)

A stress detection device for an aerial work vehicle, comprising: a traveling body configured to be able to travel; a boom provided at least on the traveling body so as to be able to move up and down; and a work table provided at a tip end of the boom. And
Stress detection means provided at any one or a plurality of locations of the aerial work vehicle, and detecting stress acting on this location,
Time signal output means for outputting an elapsed time signal at a predetermined interval from the time of running movement or the operation of the boom by the running body,
When the elapsed time signal is received from the time signal output unit, a stress value capturing unit that captures a stress value detected by the stress detecting unit when the elapsed time signal is received,
A stress detecting device for an aerial work vehicle, comprising: storage means for storing the elapsed time signal and a stress value correspondingly received by the stress value capturing means. Boom operation control means for controlling the operation of the boom,
The boom operation control means includes a workbench position detection means for detecting a position of the workbench with respect to the traveling body,
A work table position detected by the work table position detecting means corresponding to the elapsed time signal and the stress value and the elapsed time signal taken by the stress value taking means corresponding to the elapsed time signal. The stress detection device for an aerial work vehicle according to claim 1, wherein the stress detection device is configured to store the following.

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