WO2015005225A1 - 荷重検出装置及びこれを備えた作業機械 - Google Patents

荷重検出装置及びこれを備えた作業機械 Download PDF

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Publication number
WO2015005225A1
WO2015005225A1 PCT/JP2014/067820 JP2014067820W WO2015005225A1 WO 2015005225 A1 WO2015005225 A1 WO 2015005225A1 JP 2014067820 W JP2014067820 W JP 2014067820W WO 2015005225 A1 WO2015005225 A1 WO 2015005225A1
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WO
WIPO (PCT)
Prior art keywords
load
strain
pin
detection
pairs
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2014/067820
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English (en)
French (fr)
Japanese (ja)
Inventor
麻里子 水落
啓範 石井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Construction Machinery Co Ltd
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Hitachi Construction Machinery Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Priority to CN201480012659.7A priority Critical patent/CN105122023B/zh
Priority to US14/773,087 priority patent/US9523631B2/en
Priority to KR1020157023943A priority patent/KR101738559B1/ko
Publication of WO2015005225A1 publication Critical patent/WO2015005225A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G3/00—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances
    • G01G3/12—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
    • G01G3/14—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing measuring variations of electrical resistance
    • G01G3/1402—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
    • G01G3/1408—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports the supports being of the column type, e.g. cylindric
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G01L1/2287—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges constructional details of the strain gauges
    • G01L1/2293—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges constructional details of the strain gauges of the semi-conductor type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/0061—Force sensors associated with industrial machines or actuators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/08—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles
    • G01G19/12—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles having electrical weight-sensitive devices

Definitions

  • the present invention relates to a load detection device including a pin type load cell and a work machine including the load detection device.
  • Detecting the load received by each machine component constituting the machine is important for grasping the state of the machine and controlling the drive of the machine.
  • a load detection device that detects a load acting on a connection pin of a mechanism member combined in a link shape
  • a device using a pin type load cell having a load detection function on the connection pin of the mechanism member is known as a load detection device that detects a load acting on a connection pin of a mechanism member combined in a link shape.
  • the pin type load cell is inserted into the connecting portion of the mechanism member and detects a load acting on the connecting portion.
  • Patent Document 1 As a pin-type load cell suitable for this type of work machine, a pin hole provided in the axial direction of the pin and the wall surface of the pin hole or the outer periphery of the pin are located on the same circumference and are mutually connected. Two strain sensors, each mounted on two orthogonal surfaces, are proposed, and the value of pin hole diameter / pin outer diameter is 0.2 or less.
  • the pin-type load cell described in Patent Document 1 prevents the deformation of the cross-sectional shape of the pin due to the load by restricting the diameter of the pin hole, so that the load acting on the pin even if the direction of the load changes Can be measured with high accuracy.
  • the pin type load cell described in Patent Document 1 has a pin hole diameter of 0.2 or less of the pin outer diameter, the pin type load cell has a small pin outer diameter and a strain sensor is mounted in the pin hole.
  • the present invention has been made to solve the above problems, and a load detection device capable of detecting with high accuracy the magnitude and direction of a load whose direction of action changes regardless of the dimensions of the pin, and the load detection
  • An object of the present invention is to provide a working machine that is equipped with a device and that can perform work safely and efficiently.
  • the present invention relates to a load detection device, a load including a pin type load cell and a load calculation unit that calculates a load acting on the pin type load cell from a detection signal output of the pin type load cell.
  • the pin type load cell includes a pin body provided with a pin hole in an axial direction, and three or more pairs or three or more strain detectors arranged in a circumferential direction of the pin body, and the load calculation is performed.
  • a selection unit that selects a strain detection unit that is less affected by a change in cross-sectional shape of the pin body, and a strain detection unit that is selected by the selection unit.
  • a calculation unit that calculates a load acting on the pin body based on a detection signal output is provided.
  • the cross-sectional shape of a pin having a pin hole deforms asymmetrically in the vertical direction with respect to the direction of load application when subjected to a shear load.
  • a load whose action direction changes from moment to moment as the work progresses acts on the rotation shaft (pin) that connects the arm and the attachment of the work machine. For this reason, the load acting on the connection part between the arm and the attachment of the work machine using the pin type load cell in which the strain sensors are respectively attached to the two orthogonal surfaces as in the conventional pin type load cell.
  • the amount of strain caused by the deformation of the cross-sectional shape of the pin is superimposed on the detection signal of the pin type load cell depending on the direction of load application, and an accurate load cannot be detected.
  • a strain detector that is less affected by deformation of the cross-sectional shape of the pin is appropriately selected for load detection. Since the load acting on the pin can be calculated, the load acting on the pin can be accurately detected even when the cross-sectional shape of the pin having a pin hole is deformed asymmetrically in the vertical direction. it can. Therefore, it is not necessary to regulate the size of the pin hole, and it is possible to detect the load on a wide range of parts having different pin sizes.
  • the present invention is characterized in that, in the load detection device having the above-described configuration, the strain detection unit detects a shear strain at an attachment location.
  • the pin type load cell is used to detect a load acting on the link member connecting portion, and a shearing force acts on the link member connecting portion. Therefore, the load acting on the connecting portion of the link member can be accurately detected by using the strain detecting portion that detects the shear strain at the attachment location.
  • the three or more pairs of strain detection units each include a pair of two strain sensors disposed at opposing positions via the axis of the pin body. It is characterized by that.
  • a strain detection unit When a strain detection unit is configured with a pair of two strain sensors arranged at opposite positions via the axis of the pin body, the difference between the detection signal outputs of the two strain sensors is obtained, thereby obtaining the pin body. Since the influence of the bending moment acting on the pin body can be canceled, the shearing force acting on the pin body can be accurately detected.
  • the load detection device having the above-described configuration, at least one of the three pairs or more or three or more strain detection units with respect to a set position of a specific pair or one strain detection unit.
  • the set position of the pair or one strain detection unit is set to a location separated by 90 ° or more.
  • Three or more pairs or three or more strain detectors are not located in one quadrant in the circumferential direction of the pin, but at a position that is 90 ° or more away from the set position of a specific pair or one strain detector.
  • the strain detection unit having a sufficient output is selected and the influence of deformation of the cross-sectional shape of the pin is small even when a load is applied from any direction. It is possible to detect the load with higher accuracy.
  • the load calculation unit includes two pairs or two strain detection units having the smallest load calculation value from the three pairs or more or three or more strain detection units. A set is selected, and a load acting in the x-axis direction of the pin body and the y-axis direction perpendicular thereto is calculated from detection signal outputs of the selected two pairs or two strain detection units. To do.
  • the load detection value due to the asymmetric deformation of the pin body is always Appears in the positive direction. Therefore, by selecting the pair of two pairs or two strain detection units with the smallest load calculation value and calculating the load, the detection error due to the change in the cross-sectional tendency of the pin body can be minimized.
  • the load calculation unit may be affected by a change in cross-sectional shape of the pin body from the three or more pairs or three or more strain detection units using the load action direction information.
  • a small strain detector is selected, and a load is calculated from the output of the selected strain detector.
  • each strain detection part and the load action direction can be derived, and the strain detection part that is less affected by changes in the cross-sectional shape of the pin body can be found. It is possible to calculate a load that is less affected by the shape change.
  • the load calculation unit is configured such that the angle formed between the direction in which the load acts and the strain detection unit is farthest from 45 °, 135 °, 225 °, and 315 °.
  • a pair or two strain detectors are selected, and a load acting on the pin body is calculated based on detection signal outputs of the selected two pairs or two strain detectors.
  • the load acting on the pin main body is selected by selecting two pairs or two strain detecting portions farthest from the 45 °, 135 °, 225 °, and 315 ° angles between the acting direction of the load and the strain detecting portion. By calculating, high-accuracy load detection can be performed.
  • the present invention relates to a work machine, wherein the connecting portion of the mechanism member is coupled using the pin type load cell according to any one of claims 1 to 7.
  • the pin type load cell according to any one of claims 1 to 7 can perform load detection with high accuracy even when the cross-sectional shape of the pin body changes due to such a load. Therefore, the efficiency of the work can be improved while improving the safety of the work.
  • a lower traveling body an upper working body attached to an upper part of the traveling body, a working device rotatably attached to the upper working body, and the working device
  • An attachment attached to the tip of the machine via a rotation shaft, an attitude detection unit for detecting the attitude of the work machine, an arithmetic unit for calculating a load acting on the attachment, and a display for displaying the load acting on the attachment
  • a connecting portion between the working device and the attachment using the pin type load cell and the computing unit applies a load applied to the attachment portion based on the outputs of the posture detecting unit and the pin type load cell.
  • the display device displays the magnitude and direction of the load based on the output result of the arithmetic device.
  • the working machine having the attachment such as a hydraulic excavator acts on the connecting portion between the working device and the attachment regardless of the change in the load acting direction.
  • the load can be detected with high accuracy.
  • the calculation unit calculates the load applied to the attachment unit based on the output of the posture detection unit and the pin type load cell provided in each place of the work machine, it is possible to accurately grasp the direction of the load acting on the attachment. it can.
  • the load calculation result is displayed on the display device, the operator of the work machine can always clearly recognize the load acting on the attachment, and the work safety and work efficiency can be improved.
  • the load acting on the pin main body constituting the pin type load cell changes, the load acting on the pin main body with a simple configuration that is not restricted by the dimensions of the pin main body. And the direction can be detected with high accuracy.
  • FIG. 10 It is a cross-sectional view of a shear strain detector of a pin type load cell according to a conventional example. It is a figure which shows the cross-sectional shape change when the load of the pin type load cell which concerns on a prior art example is received, Fig.10 (a) is a cross-sectional shape of the pin type load cell in the load point 1C shown in FIG. 8 is a cross-sectional shape of the pin type load cell at the measurement point 1E shown in FIG. 8, and FIG. 10C is a cross-sectional shape of the pin type load cell at the support point 1D shown in FIG.
  • FIG. 12 and FIG. 12B are diagrams showing the load calculation value Fabc. It is a figure which shows the relationship between the theoretical value and measured value of a sensor output when changing a load direction from 0 degree to 360 degrees with respect to the attachment position of a strain sensor.
  • the work machine 100 includes a lower traveling body 102 that travels in contact with the ground, an upper working body 103 that is attached on the lower traveling body 102, and one end that is connected to the upper working body 103. It is mainly comprised from the working apparatus 106 attached so that rotation was possible.
  • a lower traveling body 102 shown in FIG. 1 is a so-called crawler type, a footwear 201 that is in contact with the ground, a drive wheel 202 that drives the footwear 201, a driven wheel 203 that is rotated by the footwear 201, It is comprised with the structure 204 etc. which support these.
  • the upper working body 103 is attached to the upper part of the lower traveling body 102.
  • the working machine 100 of this example is a hydraulic excavator, and the upper working body 103 is mounted on the lower traveling body 102 via a turning device or without a turning device.
  • the work device 106 is also called a work front, and is attached to the front of the upper work body 103 when viewed from the cab.
  • the work device 106 is mounted on the upper work body 103 so as to be rotatable only in the vertical direction via the rotation shaft 140, and the vertical movement is performed via the rotation shaft 141.
  • the arm 112 attached to the tip of the boom 110 so as to be rotatable only in the direction, and the attachment 123 attached to the tip of the arm 112 so as to be rotatable only in the vertical direction via the turning shaft 142. Is attached.
  • a bucket is attached to the tip of the arm 112 as the attachment 123, and the other end of the link mechanism 118 having one end connected to the arm 112 is attached to the attachment (bucket) 123. 144.
  • an end of the attachment cylinder 115 whose one end is attached to the arm 112 is connected to the link mechanism 118 via a rotating shaft 145.
  • the attachment cylinder 115 is a hydraulic cylinder, and rotates the attachment 123 about the rotation shaft 142 by expanding and contracting.
  • other attachments such as grapples, cutters, breakers, and magnets may be attached instead of the buckets.
  • FIG. 2 is a detailed view of the periphery of the attachment 123.
  • the link mechanism 118 shown in FIG. 1 includes a first link 116 spanned between the rod-side tip of the attachment cylinder 115 and the attachment 123, and a rod-side of the attachment cylinder 115.
  • a second link 117 is provided between the distal end portion and the arm 112.
  • the first link 116 is pivotally attached to the attachment 123 via a pivot shaft 144 at one end, and pivots to the attachment cylinder 115 via a pivot shaft 145 at the other end. It is attached as possible.
  • the second link 117 is pivotally attached to the arm 112 via a pivot shaft 146 at one end, and attached to the attachment cylinder 115 via the pivot shaft 145 at the other end. It is pivotally attached.
  • the link mechanism 118 may have another configuration.
  • the link mechanism 118 of FIG. 2 includes a third link member spanned between the rod-side tip of the attachment cylinder 115 and the rotation shaft 145, the rod-side tip of the attachment cylinder 115, and the arm 112.
  • a four-link type link mechanism formed by adding a fourth link member spanned between the two can be provided.
  • what consists of a combination of four or more link members can also be used.
  • the state quantity detection unit of the work machine 100 includes a posture detection device that detects the posture of the attachment 123 and a load detection device that detects a load applied to the attachment 123.
  • the work machine 100 includes a boom angle sensor 140a, an arm angle sensor 141a, and an attachment angle sensor 142a as a posture detection device that detects the posture of the attachment 123.
  • the boom angle sensor 140 a detects the rotation angle (relative angle) of the boom 110 with respect to the upper working body 103, and is provided on the upper working body 103 and the pivot shaft 140 of the boom 110.
  • the arm angle sensor 141 a detects a rotation angle (relative angle) of the arm 112 with respect to the boom 110, and is provided on the pivot shaft 141 of the boom 110 and the arm 112.
  • the attachment angle sensor 142 a detects a rotation angle (relative angle) of the attachment 123 with respect to the arm 112, and is provided on the rotation shaft 142 of the arm 112 and the attachment 123.
  • the arithmetic device 160 described later calculates an absolute angle ⁇ (ground angle) of the posture of the attachment 123 with respect to the horizontal plane. ing.
  • the work machine 100 includes pin type load cells 4 a and 4 b that detect loads in two axial directions orthogonal to each other as a load detection device that detects a load applied to the attachment 123.
  • the pin type load cells 4a and 4b are provided in place of the connecting pins provided on the rotating shaft 142 and the rotating shaft 144.
  • the pin type load cells 4a and 4b can detect a force acting on the pin body by providing a strain detection portion on the pin body formed in a required shape and size corresponding to the rotating shafts 142 and 144. Yes.
  • the specific configuration of the pin type load cells 4a and 4b will be described later in detail with reference to FIGS.
  • the pin type load cell 4 a is fixed to the attachment 123 at the set position of the rotation shaft 142 so as to rotate integrally with the attachment 123.
  • the pin type load cell 4b is fixed to the attachment 123 at the set position of the rotation shaft 144 so as to rotate integrally with the attachment 123.
  • the attachment 123 is formed with two ribs 123a and 123b for connecting the arm 112 via the rotation shafts 142 and 144 facing each other with a predetermined interval therebetween.
  • the distal end portion of the arm 112 is disposed between the two ribs 123a and 123b, and is rotated into the through hole opened in the distal end portion of the arm 112 and the through hole opened in the two ribs 123a and 123b.
  • the attachment 123 is rotatably attached to the tip of the arm 112 by passing through the pin type load cells 4a, 4b instead of the connecting pins corresponding to the moving shafts 142, 144.
  • the pin-type load cells 4a and 4b have upward contact portions with the attachment 123 as shown by white arrows in FIG. Then, downward force acts, and shear deformation occurs in the gap portions 1A and 1B between the arm 112 and the ribs 123a and 123b. For this reason, as the pin type load cells 4a and 4b, those for detecting the shear strain generated in the gap portions 1A and 1B are used.
  • FIG. 4 shows the configuration of the load measuring device 150 that measures the load acting on the connecting portion between the arm 112 and the attachment 123 from the detection signals of the posture detection device and the load detection device described above.
  • the load measuring device 150 of this example includes the biaxial pin type load cells 4a and 4b, the boom angle sensor 140a, the arm angle sensor 141a, the attachment angle sensor 142a, the arithmetic device 160, And a display device 161.
  • the arithmetic device 160 has a central processing unit and a storage device (not shown), detects the posture of the attachment 123 based on the detection signals of the angle sensors 140a, 141a, 142a, and attaches the posture information and the pin type load cells 4a, 4b. Based on this detection signal, the magnitude and direction of the force applied to the attachment 123 are calculated.
  • the display device 161 is connected to the arithmetic device 160, and displays the magnitude and direction of the force calculated by the arithmetic device 160.
  • the operator of the work machine can operate the work machine while referring to the magnitude and direction of the force displayed on the display device 161.
  • FIG. 5 is a relationship diagram of the force F 123 applied to the attachment 123, the force F 142 detected by the pin type load cell 4a, and the force F 144 detected by the pin type load cell 4b.
  • the x axis is set in the front-rear direction of the work machine 100, and the y axis is set in the vertical direction.
  • an x ′ axis is set in a direction of a line segment connecting the rotary shaft 142 and the rotary shaft 144, and a y ′ axis is set in a direction perpendicular to the x ′ axis.
  • the pin-type load cell 4a provided on the rotation shaft 142 and fixed to the attachment 123 uses the force F 142 acting on the rotation shaft 142 as the force F 142x ′ in the x′- axis direction and the y ′ axis. This is detected as a directional force F 142y ′ and output to the arithmetic device 160.
  • the pin-type load cell 4b provided on the rotation shaft 144 and fixed to the attachment 123 has a force F 144 acting on the rotation shaft 144 as a force F 144x ′ in the x′- axis direction and a y′- axis. This is detected as a directional force F 144 y ′ and output to the arithmetic device 160.
  • the computing device 160 calculates the angle ⁇ (see FIG. 5) of the attachment 123 with respect to the horizontal plane (x-axis direction) based on the detection values of the boom angle sensor 40a, the arm angle sensor 41a, and the attachment angle sensor 42a (attitude detection device). To do.
  • the computing device 160 uses the x-axis direction component F 123x and the y-axis direction component F 123y of the force F 123 applied to the attachment 123 using F 123x ′ and F 123y ′ calculated from the angle ⁇ and the above equation. The following formula is used for calculation. Thereby, the arithmetic unit 160 can calculate the magnitude and direction of the force F 123 acting on the attachment 123.
  • the load detection device includes a pin type load cell 4 and a load calculation unit 30 that calculates a load acting on the pin type load cell 4 from a detection signal of the pin type load cell 4. Composed.
  • the pin type load cell 4 is a general term for the pin type load cells 4a and 4b.
  • the pin type load cell 4 includes a pin body 1 having a predetermined dimension formed using structural carbon steel such as S45C, and a shear strain detection attached in the pin hole 2 of the pin body 1.
  • the pin hole 2 is a hole that is concentric with the pin body 1 and is provided in the axial direction of the pin body 1.
  • the pin hole 2 can be a through-hole penetrating the pin body 1. It can also be a semi-through hole provided so as to reach a portion corresponding to the shear strain generating portion 1A, 1B.
  • a recessed portion 1a is formed at a predetermined position on the outer periphery of the pin body 1, that is, at a portion corresponding to the shear strain generating portions 1A and 1B shown in FIG.
  • a plurality of strain sensors constituting the shear strain detector 20 are provided in a portion corresponding to the formation portion of the recess 1 a inside the pin hole 2.
  • the shear strain detector 20 is composed of a plurality of strain sensors that detect shear strain acting on the pin body 1.
  • a generally used metal resistance type strain gauge a semiconductor strain sensor using an impurity diffusion resistance in which an impurity is introduced into a single crystal silicon substrate, or the like can be used.
  • a pair of two strain sensors arranged opposite to each other are arranged in the circumferential direction of the pin hole 2.
  • the strain sensors 21a and 22a constitute a pair of strain sensors
  • the strain sensors 21b and 22b constitute another pair of strain sensors
  • the strain sensors 21c and 22c are still another pair of strain sensors.
  • the sensor pairs (21a, 22a), (21b, 22b), and (21c, 22c) are arranged at positions ⁇ a, ⁇ b, and ⁇ c from the x-axis, respectively.
  • the strain sensors 24a and 25a, 24b and 25b, and 24c and 25c set in the other shear strain generator 1B are similarly configured. Each pair of strain sensors detects a shear strain generated at each sensor mounting position. Note that the three pairs of strain sensors are arranged in the circumferential direction of the pin hole 2 even when the cross-sectional shape of the pin body 1 is deformed asymmetrically with respect to its axis due to a load. This is because there are two pairs of strain sensors at the position. In addition, the two strain sensors are arranged opposite to each other via the shaft center in order to eliminate the influence of the strain due to the bending moment. If the influence of the strain due to the bending moment can be ignored, the two strain sensors are disposed in pairs. There is no need to arrange three strain sensors in the circumferential direction of the pin hole 2.
  • the arrangements ⁇ a, ⁇ b, and ⁇ c of the three pairs of strain sensors described above do not necessarily need to be equally spaced with respect to the circumferential direction of the pin hole, and are 90 ° to 180 ° with respect to the set position of a certain pair of strain sensors. What is necessary is just to arrange
  • the arrangement in which the angle between any two of the three pairs of strain sensors is 90 ° is: It is desirable to avoid it. These reasons will be described in detail in the following (the principle of error generation and the principle of error avoidance). Further, the arrangement of the strain sensors provided in the shear strain generating unit 1A and the strain sensors provided in the shear strain generating unit 1B are not necessarily the same.
  • ⁇ Error generation principle and error avoidance principle A load whose direction changes from moment to moment as the work progresses acts on the rotating shaft of the work machine.
  • the measurement error generation principle and the tendency of the error when a load that changes direction is applied to the pin type load cell instead of the rotation axis, and the measurement error of the measurement error by providing three pairs or three strain sensors. The reason why avoidance is possible will be described.
  • FIG. 8 is an enlarged view of the shear deformation generating portion 1A of the pin type load cell 4.
  • strain sensors 21a and 22a are provided on the inner wall of the pin hole 2 at an intermediate position 1E (measurement point) between the load point 1C and the support point 1D.
  • the strain sensors 21a and 22a detect expansion and contraction in the direction of 45 ° with respect to the axial direction in the vicinity of the measurement point, and the difference between the output values of the two strain sensors 21a and 22a arranged so as to face each other is used as shear strain. Output.
  • the strain sensors 21a and 22a are on the sensor mounting surface of the load acting on the pin type load cell 4. Detects shear strain due to the corresponding directional component.
  • ⁇ is a constant representing the sensitivity of the strain sensor to the load.
  • the force Fx in the x-axis direction and the force Fy in the y-axis direction can be calculated by multiplying the output values Sx and Sy of each sensor pair by 1 / ⁇ .
  • FIG. 10 By the way, in the actual pin body 1, the cross-sectional shape is deformed as shown in FIG. 10 when subjected to a load due to the dimensional tolerance of the pin hole 2 and the pin mounting portion.
  • 10A is a load point 1C
  • FIG. 10B is a measurement point 1E
  • FIG. 10C is an enlarged view of deformation of a cross-sectional shape at a support point 1D.
  • the load point 1C and the support point 1D are asymmetric in the vertical direction due to the influence of the load.
  • the load point 1C has a shape with a small upper portion and a large lower portion
  • the support point 1D has a shape with a large upper portion and a small lower portion.
  • the detection value of the strain sensor 21 includes the strain generated by the asymmetric deformation in addition to the strain due to the shear deformation.
  • the magnitude of the influence due to the deformation of the asymmetrical cross-sectional shape varies depending on the load acting direction, and the strain in a certain load acting direction If the load value is calculated using the calibration value of the sensor, a measurement error occurs when the load acting direction changes. Therefore, when the cross-sectional shape of the pin body 1 is deformed asymmetrically in the vertical direction under load, the strain sensor pair (21a, 22a) provided in the 0 ° direction of the pin body 1 and the strain provided in the 90 ° direction. Based on the output values Sx and Sy (see Equation 3) of the sensor pair (21b, 22b), the load F acting on the pin main body 1 and its acting direction cannot be obtained.
  • FIG. 11 shows the tendency of the theoretical value and the measured value of the load in the x-axis direction and the y-axis direction when the load acting direction is changed from 0 ° to 360 °.
  • 11A is a graph showing the direction of the straight line passing through the origin O as the load direction, and the distance from the origin O as the load measurement value.
  • FIG. 11B shows the load direction as the horizontal axis and the load measurement as the vertical axis. It is a graph figure made into a value.
  • the load measurement error varies depending on the load acting direction and tends to be particularly large at 45 °, 135 °, 225 °, and 315 °.
  • the calculated load value tends to take a minimum value at 0 °, 90 °, 180 °, and 270 °. That is, when using a strain sensor calibration result using loads in the 0 ° direction and 90 ° direction, an error always occurs in the positive direction.
  • the magnitude of the load measurement error depends on the rigidity of the pin, i.e., the pin material, outer diameter, and pin hole diameter, and decreases when the pin hole diameter is small, but the relationship between the direction of load application and the magnitude of the error is It always shows the same tendency as above.
  • the load measurement error can be reduced if measurement can be performed while avoiding 45 °, 135 °, 225 °, 315 ° and the vicinity thereof, which are easily affected by asymmetric deformation of the cross-sectional shape and increase the measurement error. . That is, when three pairs or three strain sensors are arranged in the circumferential direction of the pin body 1 as in the pin type load cell 4 shown in FIG. If at least another pair of strain sensors is installed at a position where the angle is ⁇ 180 °, and an arrangement in which the angle between any two of the three pairs of strain sensors is 90 ° is avoided, the pin body 1 However, at least two pairs or two strain sensors can be hardly affected by the deformation of the pin body 1 regardless of the direction in which the load acts. Therefore, by calculating the load acting on the pin body 1 based on the detection signals of these two pairs or two strain sensors, highly accurate load measurement can be performed.
  • the load calculation unit 30 uses an input unit 31 that inputs a detection signal of the shear strain detection unit 20 and detection signals of two pairs of strain sensors selected from three pairs of strain sensors.
  • a calculation unit 32 that calculates the magnitude of a load applied to three types of pin bodies 1 with different combinations of strain sensor pairs, and a combination of the three types of strain sensors that has the smallest calculated load magnitude.
  • a selection unit 33 to be selected and an output unit 34 that outputs the biaxial loads Fx and Fy calculated from the selected strain sensor.
  • the load calculation unit 30 can be configured with a microcomputer or the like. The gist of the present invention suffices if the load calculation unit 30 includes a calculation unit and a selection unit. The selection unit of the strain signal input to the input unit 31 is arranged in the previous stage, and the selected strain signal is selected. The calculation unit for calculating the biaxial loads Fx and Fy can be arranged in the subsequent stage.
  • a strain sensor pair (21a, 22a) and a strain sensor pair (21b, 22b) are used as a method for calculating a load by selecting two pairs from the three pairs of strain sensors shown in FIG.
  • (21b, 22b) and the strain sensor pair (21c, 22c) there are three possible cases: using the strain sensor pair (21a, 22a) and the strain sensor pair (21c, 22c).
  • the load measurement error is always positive. Occurs in the direction.
  • the combination of the strain sensor pair with the smallest measurement error has the smallest value among the three load values calculated using the detection signals of the two pairs of strain sensors. That is, the load value Fab calculated using the strain sensor pair (21a, 22a) and the strain sensor pair (21b, 22b), the strain sensor pair (21b, 22b), and the strain sensor pair (21c, 22c) were calculated.
  • the load values Fbc calculated using the load value Fac the strain sensor pair (21a, 22a) and the strain sensor pair (21c, 22c)
  • the strain sensor pair (21a, 22a) and the strain sensor pair (21c, 22c) when the Fab is the smallest, the strain sensor pair (21a, 22a) and the strain
  • the sensor pair (21b, 22b) is a combination of sensors with the smallest measurement error.
  • the load calculation unit 30 calculates the load value in each of the three combinations, selects the combination having the smallest calculated load value as the best combination, and calculates the load value calculated using the combination as the load calculation. Value.
  • the load values in the x-axis direction and the y-axis direction in each combination are calculated as follows.
  • Fa, Fb, and Fc are obtained by converting the output of each sensor pair into a force dimension, and are calculated by multiplying the difference between the outputs of two sensors forming each sensor pair by the calibration value of the strain sensor. Value.
  • the magnitudes Fab, Fac, and Fbc of the load value can be calculated as follows.
  • the load calculation unit 30 calculates the loads F1Ax and F1Ay acting on the shear deformation generation unit 1A based on the load calculation values in each combination as follows.
  • the load calculating unit 30 calculates the loads F4x and F4y acting on the pin type load cell 4 as the sum of the load value detected in the shear deformation generating unit F1A and the load value detected in the shear deformation generating unit F1B. Output as values Fx and Fy.
  • FIG. 12A is a diagram showing Fab, Fac, Fbc when the load acting direction is changed in the pin type load cell 4 according to the present embodiment
  • FIG. 12B shows the load calculation value Fabc.
  • FIG. As shown in this figure, three pairs of sensors are arranged, the load is calculated using two of them, and the combination with the smallest load calculation value among the combinations of all sensors is selected as the best combination. Therefore, the error can be significantly suppressed as compared with the case where the configuration of the conventional example shown in FIG. 9 is used. In the conventional example, a large error occurs when the load acting direction is around 45 °, 135 °, 225 °, and 315 °. However, in the configuration of the present invention, the error is kept small even in such a load acting direction. It can be seen that highly accurate measurement is possible regardless of the direction of load application.
  • the load application direction is unknown, a sensor having a small influence of asymmetric deformation is selected based on the output value of the shear strain detection unit 20, and the method used for load calculation is shown.
  • the load action direction information is used to calculate the angle between the load action direction and the sensor, and based on this angle information, the pin body is placed at a position where the influence of the cross-sectional shape change is large.
  • the sensor pair may be avoided, and two pairs that are less affected by the change in cross-sectional shape may be selected and used for load calculation.
  • FIG. 13 shows the relationship between the theoretical value of the sensor output and the measured value when the load direction is changed from 0 ° to 360 ° with respect to the sensor mounting position.
  • the difference between the theoretical value and the measured value shown in FIG. 13 is the influence of the cross-sectional deformation of the pin body, but this magnitude varies depending on the angle between the load acting direction and the sensor mounting position. Therefore, if the angle between the load acting direction and the sensor is used, it is possible to select two pairs of the three sensor pairs that are less affected by the cross-sectional deformation of the pin body. As described above, generally, the influence of the cross-sectional deformation of the pin body tends to occur near 45 °, 135 °, 225 °, and 315 ° with respect to the load direction.
  • the load acting direction there is a case where the working force is limited to the gravity direction among the cases where the pin type load cell is applied to the measurement of the load acting on the attachment part of the work machine.
  • the direction of the load acting on the other load cell can be calculated by deriving the angle between the pin type load cell and the direction of gravity from an inclination angle sensor, an angle sensor or the like.
  • the shear strain detection unit 20 includes a strain sensor on the inner wall of the pin hole 2.
  • the shear strain detection unit 20 only needs to be able to detect the shear strain of the shear deformation generation units 1A and 1B.
  • a configuration may be adopted in which a strain sensor is provided in a recess formed in the outer periphery of the pin body 1, or a configuration in which a strain detection block is inserted into the pin hole and a strain sensor is provided on the detection block surface (for example, Japanese Patent Laid-Open Publication No. 61-145426).
  • the arrangement method of each sensor pair and the load calculation method in the load calculation unit 30 may be the same as those in the above embodiment.
  • strain sensors are arranged so as to face each other as the shear strain detection unit 20 .
  • two strain sensors are arranged on the same surface. You may arrange
  • three strain sensors may be arranged. In this case, the strain sensor may be arranged so that at least one strain sensor exists at a position 90 ° or more away from the strain sensor 21A.
  • the work machine can detect the magnitude and direction of the load acting on the rotating shaft (pin type load cell) with high accuracy even when the load acting direction changes from moment to moment. Since the possible load detection device is provided, the magnitude and direction of the load acting on the attachment 123 can be detected with high accuracy, and the worker or the work manager can accurately grasp the state of the work machine. Therefore, it is possible to improve the safety of work and the efficiency of work and work management.
  • the load detecting device is used to detect the magnitude and direction of the load acting on the attachment 123
  • the gist of the present invention is not limited thereto.
  • the load detection device according to the embodiment can be applied not only to work machines but also widely to general machine load detection.

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  • Chemical & Material Sciences (AREA)
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PCT/JP2014/067820 2013-07-09 2014-07-03 荷重検出装置及びこれを備えた作業機械 Ceased WO2015005225A1 (ja)

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CN201480012659.7A CN105122023B (zh) 2013-07-09 2014-07-03 载荷检测装置及具备该载荷检测装置的作业机械
US14/773,087 US9523631B2 (en) 2013-07-09 2014-07-03 Load detecting device and working machine provided with same
KR1020157023943A KR101738559B1 (ko) 2013-07-09 2014-07-03 하중 검출 장치 및 이것을 구비한 작업 기계

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CN105333984B (zh) * 2015-12-06 2018-02-23 吉林大学 一种挖掘机载荷测试装置
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CN113232612B (zh) * 2021-06-30 2022-11-04 北京哈崎机器人科技有限公司 一种足式机器人触地感应机构及足式机器人
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