JP2020011795A - Mobile crane - Google Patents

Abstract

To provide a mobile crane which can detect information necessary for safely erecting and lodging an undulation member in assembling work and dismantling work of the crane without causing an operator to perform troublesome input work.SOLUTION: A crane 10 comprises a strain detection part 90 for detecting strain generated at least at one crawler frame 1 out of a pair of the crawler frames 1, and the strain detection part 90 can detect the strain generated in a portion in which a position in a cross direction of at least one crawler frame 1 is included in a range R between a rotating axis CB of a first wheel 4a and a rotating axis CA of a first lower roller 6A.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a mobile crane.

  Conventionally, a mobile type including a self-propelled lower traveling body, an upper revolving body rotatably mounted on the lower traveling body, and an up-and-down member including a boom that is rotatably mounted on the upper revolving body. Crane is known. The lifting operation of the mobile crane is performed in a state where the boom is standing upright from the upper swing body (standing state). In the assembling work for assembling the crane, the boom is attached to the upper revolving superstructure in a state where the boom is laid down in a posture substantially parallel to the ground (downward state). Then, when performing the suspending operation, the posture of the boom is changed from the lying state to the standing state by the standing operation in which the inclination angle of the boom with respect to the ground gradually increases. On the other hand, in the disassembling operation for disassembling the crane, the posture of the boom is changed from the upright state to the downside state by a falling operation in which the inclination angle of the boom with respect to the ground gradually becomes smaller.

  In the crane as described above, when the angle of inclination of the boom with respect to the ground changes, the position of the center of gravity of the up-and-down member including the boom changes, thereby changing the weight of the up-and-down member and the moment resulting from the position of the center of gravity. In order to prevent the crane from overturning due to such a change in the moment, the mobile crane includes a moment limiter. In the lifting operation, when the magnitude of the overturning moment of the crane reaches a predetermined threshold value due to the change in the inclination angle of the boom, a warning is issued by the moment limiter or the operation of the crane is stopped. Safety can be ensured.

  On the other hand, the assembling operation and the disassembling operation involve a large undulating operation between the upright state and the laid state as described above, and therefore differ from the suspending operation in the following points. Since the moment limiter is basically a device related to the stability during the lifting operation, the lifting capability is set within the working range assumed in the lifting operation in the moment limiter. On the other hand, the assembling work and the disassembling work are performed not only when the work is performed within the work range in the hanging work but also when the boom is angled with respect to the ground (the boom is lying down). It may be performed outside the working range. As described above, in the range other than the working range of the lifting work, the lifting capacity is not set in the moment limiter. Therefore, in the assembling operation and the disassembling operation, the operation of reducing the boom angle in a state where the moment limiter is stopped or in a state where the moment limiter is not stopped but the limiter generated in the moment limiter is released. Is performed. Therefore, in the assembling operation and the disassembling operation, the crane operator is required to have experience and knowledge to determine whether or not the inclination angle of the boom is a safe angle. Various techniques have been proposed in order to enhance safety in such assembling work and disassembling work.

  For example, Patent Document 1 discloses a crane operation support device. In a crane equipped with the operation support device, the combination of the boom length and the jib length of the front attachment (raising member) is stable when the front attachment is tilted down with the relative angle between the boom and the jib set as the first target angle. In the case of a combination that can obtain the property, the tilting operation of the front attachment is performed until the tip of the jib comes into contact with the ground while the relative angle of the jib to the boom is kept at the first target angle. .

  In the technique disclosed in Patent Document 1, an operator inputs in advance various information such as information on a boom and a jib, and a target value of a relative angle between the boom and the jib to the operation support device.

JP 2014-162607 A

  By the way, there are various specifications for cranes. That is, there are various specifications such as a crane having a boom and a jib, a crane having a boom but not having a jib, and a crane having a strut and a lattice mast, as in Patent Document 1. As described above, in the crane, the type of the undulating member is selected and the length of the boom and the length of the jib are adjusted according to the required capacity and the type of work.

  In the technique disclosed in Patent Document 1 described above, it is necessary to input information on a boom and a jib for all of these specifications and to input the target value corresponding to each specification. The operation of grasping the information and the target values of the above and inputting them to the device is complicated, and there is a possibility that an input error by the operator may occur.

  The present invention has been made in order to solve the above-described problems, and is intended to safely raise and lower a undulating member in a crane assembling operation and a disassembling operation without an operator performing a complicated input operation. It is an object of the present invention to provide a mobile crane capable of detecting necessary information for a vehicle.

  (1) A mobile crane according to the present invention includes a lower traveling structure, an upper revolving structure, an undulating member, and a strain detector. The lower traveling body includes a pair of crawler frames extending in the front-rear direction and arranged at intervals in the left-right direction, and an end located in a first direction that is one of the front-rear directions of each crawler frame. A first wheel rotatably supported and a second wheel rotatably supported at ends of the respective crawler frames located in a second direction opposite to the first direction, and the first wheel and the crawler frame; A crawler that is endlessly supported by the second wheel and that can move around; and a crawler frame that is rotatably supported at a lower portion of each crawler frame and that is spaced apart in the front-rear direction between the first wheel and the second wheel. And a plurality of lower rollers arranged to guide the crawler. The upper revolving superstructure is pivotably supported on the lower traveling superstructure. The undulating member includes a boom supported by the upper swing body so as to be able to undulate. The strain detector is for detecting a strain generated in at least one of the pair of crawler frames. When the one closest to the first wheel among the plurality of lower rollers is a first lower roller, the strain detection unit is configured such that, in the at least one crawler frame, the position in the front-rear direction is the position of the first wheel. It is configured to be able to detect a strain generated in a portion included in a range between a rotation axis and the rotation axis of the first lower roller.

  The present invention relates to a distortion generated in a crawler frame of a lower traveling body in a crane assembling operation and a disassembling operation, particularly, in a range between a rotation axis of the first wheel and a rotation axis of the first lower roller in the crawler frame. The strain generated in the included part was made with the focus on the fact that it is useful in determining the stability before and after the crane, and the detection of the strain makes it possible to assemble and disassemble the crane. Safe operation becomes possible. Specifically, it is as follows.

  In the mobile crane of the present invention, a state in which the front end of the boom is disposed at a position deviated in the first direction from the base end of the boom in the front-rear direction, specifically, for example, the In a state where the mobile crane is arranged in a posture extending in the first direction of the front-rear direction from the revolving structure, a moment in a direction in which the mobile crane tends to fall in the first direction is generated. Each of the crawler frames is distorted. Then, when the up-and-down member performs the upright operation and the downturn operation, the position of the center of gravity of the up-and-down member fluctuates in the front-rear direction, so that the moment increases and decreases, whereby the strain also increases and decreases. The distortion in each crawler frame is remarkably generated in the above-described portion in each crawler frame, that is, in a portion whose position in the front-rear direction is included in a range between the rotation axis of the first wheel and the rotation axis of the first lower roller. . For this reason, by providing the strain detection unit capable of detecting the strain generated in the portion of at least one crawler frame of the pair of crawler frames, it is possible to effectively detect the strain generated in the at least one crawler frame Can be.

  Moreover, the strain at the site detected by the strain detecting unit is actually generated in the crawler frame as a result of the upright operation or the laying operation of the up / down member, and the strain is caused by the increase and decrease of the moment. Increases or decreases in correlation. Therefore, the strain detected in the above-mentioned portion is used to determine (estimate) the crane state such as a stable state in which the front and back of the crane are balanced and stable, and an unstable state in which the crane is approaching to fall in the first direction. And no information on the combination of the boom length and the jib length is required for the determination. Therefore, in the mobile crane of the present invention, the operator inputs information on the combination of the boom length and the jib length and information on the target value of the relative angle between the boom and the jib as in the operation support device of Patent Document 1 described above. This eliminates the need for such complicated work.

  Therefore, in the mobile crane of the present invention, even if the operator does not perform a complicated input operation, the information on the crane state necessary for safely raising and lowering the up-and-down member in the assembling operation and the disassembling operation of the crane. Can be detected. Then, the detected information is used for the crane to safely stand and fall.

  (2) In the mobile crane, the at least one crawler frame has a frame main body extending in the front-rear direction and a base end connected to a front end of the frame main body in the first direction. A tumbler bracket extending from the portion in the first direction to support the first wheel, wherein the strain detection unit detects a strain generated at the base end of the tumbler bracket or the tip of the frame body. Preferably, it is configured to be detectable.

  In this aspect, it can be considered that the tumbler bracket connected to the front end of the frame body in the first direction has one end fixedly supported and the other end in a free cantilever state. As described above, when the upright member performs the upright operation and the downturn operation in the posture extending in the first direction in the front-rear direction from the upper revolving unit, the moment in the direction in which the mobile crane tends to fall in the first direction is generated. And a strain is generated in each of the pair of crawler frames due to the moment. At this time, the tumbler bracket receives a bending load, thereby generating a bending moment for bending the tumbler bracket. Then, in the tumbler bracket in the cantilever state, the bending moment at the base end of the tumbler bracket is larger than the bending moment at the tip end of the tumbler bracket. Therefore, when the strain detection unit can detect the strain generated at the base end of the tumbler bracket, the strain generated in the crawler frame when the undulating member performs the upright operation and the undulating operation is detected with high sensitivity. Can be. The distal end of the frame body is a portion connected to the base end of the tumbler bracket, and is a portion adjacent to the base end of the tumbler bracket. Therefore, even when the strain detecting section can detect the strain generated at the tip of the frame main body, the strain generated in the crawler frame when the undulating member performs the upright operation and the laying operation is detected with relatively high sensitivity. can do.

  Here, the base end of the tumbler bracket refers to a portion of the tumbler bracket closer to the frame body than the center of the tumbler bracket in the first direction. Further, the leading end of the frame body refers to a portion of the frame body closer to the tumbler bracket than a portion corresponding to the rotation axis of the first lower roller.

  (3) In the mobile crane, the distal end of the frame body and the proximal end of the tumbler bracket, which are connected to each other, are connected to a web portion extending in a plate shape in a vertical direction and an upper end of the web portion. An upper flange portion extending in a plate shape in the front-rear direction, and a lower flange portion connected to a lower end of the web portion and extending in a plate shape in the front-rear direction, the strain detecting unit includes: It is preferable to include at least one of a first device for detecting the strain of the upper flange portion and a second device for detecting the strain of the lower flange portion.

  In this aspect, the leading end of the frame main body and the base end of the tumbler bracket that are connected to each other, that is, the connecting portion between the frame main body and the tumbler bracket and the adjacent portion adjacent to the connecting portion in the front-rear direction are the webs. It has a structure including an I-shaped (H-shaped) cross-sectional shape composed of a portion, an upper flange portion, and a lower flange portion. When the pair of crawler frames is subjected to a bending load in the vertical direction when each of the pair of crawler frames undergoes bending deformation when the up-and-down member performs the upright operation and the falling operation, the crawler frame is higher than the neutral surface in each crawler frame. Is compressed and shrunk, and the portion below the neutral surface is stretched and stretched. The upper and lower strains of each crawler frame increase in proportion to the distance from the neutral plane. In the cross-sectional structure of the I-type (H-type), since the upper and lower flanges are located at relatively large distances from the neutral plane, a relatively large strain (bending stress) is generated at the upper flange and the lower flange. Therefore, as in this embodiment, the strain detector includes at least one of the first device that detects the strain of the upper flange portion and the second device that detects the strain of the lower flange portion, so that a relatively large strain is generated. Since the detection can be performed, the detection sensitivity of the strain can be increased.

  In particular, when the distortion detection unit includes both the first device and the second device, the accuracy of detecting the distortion can be further improved. Specifically, it is as follows. Each crawler frame supports a pair of wheels, and the pair of wheels supports endless crawlers. Therefore, each crawler frame has not only the above-described vertical bending load but also the front-rear direction ( It is considered that the shaft load is also received in the longitudinal direction of the crawler frame). In this case, the bending stress (compressive stress) obtained based on the strain of the upper flange portion detected by the first device includes an axial component caused by the axial load. Similarly, the bending stress (tensile stress) obtained based on the strain of the lower flange portion detected by the second device includes an axial component resulting from the axial load. Therefore, the bending stress obtained by calculating the difference between the compressive stress and the tensile stress is obtained by removing the component in the axial direction caused by the shaft load. This makes it possible to calculate the bending stress with higher accuracy.

  (4) The mobile crane may further include a calculation unit that calculates a moment in a direction in which the mobile crane tends to fall in the first direction based on a detection signal output by the strain detection unit. Good.

  In this aspect, the moment is calculated by the calculation unit based on the detection signal from the strain detection unit, and thereby, the moment that causes the crane to fall down is obtained. The frequency of detection by the strain detector and the frequency of calculation by the calculator are not particularly limited. The detection by the strain detection unit and the calculation by the calculation unit may be performed, for example, at every preset time, or may be performed continuously (always).

  (5) In the mobile crane, the strain detector is a first strain detector for detecting a strain generated in a first crawler frame of the pair of crawler frames. A second strain detecting unit configured to detect a strain generated in the second crawler frame, wherein the second strain detecting unit is configured such that, in the second crawler frame, the position in the front-rear direction is the rotation axis of the first wheel. It is preferable that a distortion generated in a portion included in a range between the rotation axis of the first lower roller and the rotation axis of the first lower roller can be detected.

  In this aspect, since it is possible to detect the strain generated in both of the pair of crawler frames, for example, when the up-and-down member performs the upright operation and the downturn operation, the crane may not be balanced on the left and right. Also, information on the state of the crane according to the left and right balance is detected by the respective strain detection units. Therefore, compared to the case where the strain detection unit can detect only the strain generated in one crawler frame, the crane state required for safely raising and lowering the undulating member in the crane assembling work and disassembling work is described. Information can be detected more accurately.

  (6) The mobile crane may further include a notifying device for notifying the operator of information on a front-rear balance in the mobile crane based on a detection signal output by the strain detection unit. Good.

  In this aspect, since the operator can obtain information on the front-back balance of the crane through the notification device, the operator can operate the crane using the information as an index. Can work.

  According to the present invention, there is provided a mobile crane capable of detecting information necessary for safely raising and lowering an up-and-down member in a crane assembling operation and a disassembling operation without an operator performing a complicated input operation. Can be provided.

It is a side view which shows the mobile crane which concerns on one Embodiment of this invention, and shows the attitude | position at the time of suspending work, and is a figure at the time of an up-and-down member being in an upright state. It is a block diagram which shows the functional structure of the mobile crane of FIG. It is a top view which shows the lower traveling body of the mobile crane of FIG. It is a side view which shows the lower traveling body of the mobile crane of FIG. It is a side view which shows the crawler frame which comprises the lower traveling body of the mobile crane of FIG. FIG. 5 is a side view when the tip of the crawler frame is viewed in a direction of an arrow VI in FIG. 3. It is the figure which showed typically the stress distribution which arises in the cross section of the measurement object of a strain in the front-end | tip part of a crawler frame. FIG. 2 is a side view schematically showing a posture of the mobile crane shown in FIG. 1 during an assembling operation or a disassembling operation, and is a diagram when the undulating member is in an upright state. FIG. 2 is a side view schematically illustrating a posture of the mobile crane of FIG. 1 during an assembling operation or a disassembling operation, and is a diagram when an up-down member performs a standing operation or a falling operation. FIG. 2 is a side view schematically illustrating a posture of the mobile crane of FIG. 1 during an assembling operation or a disassembling operation, and is a diagram when an up-down member performs a standing operation or a falling operation. FIG. 2 is a side view schematically showing a posture of the mobile crane of FIG. 1 during an assembling operation or a disassembling operation, and is a diagram illustrating a state in which a moment balance position approaches a tipping fulcrum. FIG. 2 is a side view schematically illustrating a posture of the mobile crane of FIG. 1 during an assembling operation or a disassembling operation, and is a diagram when an up-down member performs a standing operation or a falling operation. FIG. 2 is a side view schematically illustrating a posture of the mobile crane of FIG. 1 during an assembling operation or a disassembling operation, and is a diagram when an up-down member performs a standing operation or a falling operation. FIG. 6 is a side view when the tip of the crawler frame is viewed in a direction of an arrow VI in FIG. 3, and is a diagram illustrating a first modification of the embodiment. FIG. 6 is a side view when the tip of the crawler frame is viewed in a direction of an arrow VI in FIG. 3, and is a diagram illustrating a modified example 2 of the embodiment. FIG. 6 is a side view when the tip of the crawler frame is viewed in a direction of an arrow VI in FIG. 3, and is a diagram illustrating a modification 3 of the embodiment. It is a perspective view which shows the modification 4 of the said embodiment typically.

  Hereinafter, a mobile crane according to an embodiment of the present invention will be described with reference to the drawings.

[Mobile crane]
Drawing 1 is a side view showing mobile crane 10 concerning an embodiment, and shows a posture at the time of suspending work, and is a figure when an up-and-down member is in an upright state. FIG. 2 is a block diagram showing a functional configuration of the mobile crane 10 of FIG. The directions such as “up”, “down”, “front”, “rear”, “right”, and “left” shown in the drawings correspond to the structure and the undulating method of the mobile crane according to the embodiment of the invention. It is shown for the sake of convenience for the sake of explanation, and does not limit the moving direction, usage mode, and the like of the mobile crane. In addition, one of the front and rear directions is defined as a first direction D1, and the other of the front and rear directions is defined as a second direction D2 (see FIGS. 5, 10, and 13).

  As shown in FIG. 1, the crane 10 includes a self-propelled lower traveling body 11, an upper revolving body 12 mounted on the lower traveling body 11 so as to be rotatable around an axis, an undulating member, and a mast 20. , A counterweight 13 loaded on the rear part of the upper revolving unit 12, one or a plurality of strain detectors 90 (see FIG. 2), a controller 100 (see FIG. 2), and a notification device 110 (see FIG. 2). , Is provided. In the present embodiment, the undulating member includes a boom 14, a jib 17, an upper strut 22, and a lower strut 21.

  The boom 14 is rotatably and detachably attached to the upper swing body 12. The boom 14 shown in FIG. 1 has a so-called lattice-type boom main body 15, a base end 14A, and a tip end 14B.

  The boom main body 15 includes a base member 15A, one or a plurality of (two in the illustrated example) intermediate members 15B and 15C, and a tip member 15D. The base member 15A is connected to the front portion of the upper swing body 12 so as to be rotatable in the up-and-down direction. The intermediate members 15B and 15C are detachably connected to the distal end of the proximal member 15A in that order. The tip member 15D is detachably connected to the tip of the intermediate member 15C. Note that the intermediate members 15B and 15C can be omitted.

  The jib 17 is rotatably and detachably attached to the tip of the boom 14. The jib 17 has a lattice structure in the illustrated example. A base end 17A of the jib 17 is rotatably connected to a distal end 14B of the boom 14. The center axis of rotation of the jib 17 is parallel to the center axis of rotation of the boom body 15 with respect to the upper swing body 12. As shown in FIG. 1, the tip 17B of the jib 17 includes a roller 17R that supports the jib 17 when the tip 17B comes into contact with the ground and is rotatable on the ground.

  The upper strut 22 and the lower strut 21 are provided for rotating the jib 17. The upper strut 22 is rotatably attached to the distal end portion 14B of the boom 14. The lower strut 21 is rotatably attached to the distal end portion 14B of the boom 14 at a position behind or below the upper strut 22. The upper strut 22 and the lower strut 21 are configured to be detachable from the distal end portion 14B of the boom 14.

  A pair of left and right backstops 23 are provided on the upper rotating body 12. When the boom 14 reaches the upright posture shown in FIG. 1, the back stops 23 come into contact with the left and right sides of the base end member 15A of the boom 14, and the boom 14 is forced into strong wind or the like by this contact. Regulates being pushed backwards.

  The lower strut 21 is held in a posture protruding from the tip end portion 14B of the boom 14 to the boom rising side (the left side in FIG. 1). As means for maintaining this posture, a pair of left and right backstops 25 and a pair of left and right strut guy lines 26 are interposed between the lower strut 21 and the boom 14. The backstop 25 is interposed between the distal end member 15D and an intermediate portion of the lower strut 21, and supports the lower strut 21 from below. The guy line 26 is stretched so as to connect the distal end portion 21B of the lower strut 21 and the base end member 15A, and regulates the position of the lower strut 21 by the tension.

  The upper strut 22 is connected to the jib 17 so as to rotate in conjunction with the jib 17. Specifically, a pair of left and right jib guy lines 28 is stretched so as to connect the tip 22B of the upper strut 22 and the tip 17B of the jib 17. Therefore, the jib 17 is also rotationally driven by the rotational driving of the upper strut 22.

  The mast 20 has a base end 20A and a rotating end 20B. A base end 20A of the mast 20 is rotatably connected to the upper swing body 12. The rotation axis of the mast 20 is located parallel to the rotation axis of the boom 14 and immediately behind the rotation axis of the boom 14. That is, the mast 20 is rotatable in the same direction as the up and down direction of the boom 14. On the other hand, the rotating end 20B of the mast 20 is connected to the tip 14B of the boom 14 via a pair of left and right boom guy lines 24. This connection causes the rotation of the mast 20 and the rotation of the boom 14 to cooperate.

  Various winches are mounted on the crane 10. Specifically, a boom hoisting winch 30 for raising and lowering the boom 14, a jib hoisting winch 32 for rotating the jib 17 in the hoisting direction, and a main winding for hoisting and lowering the suspended load. Winch 34 and auxiliary winch 36 are mounted.

  The boom hoisting winch 30 winds and unwinds the boom hoisting rope 38. Then, the boom hoisting rope 38 is routed so that the mast 20 is rotated by the winding and feeding. Specifically, sheave blocks 40 and 42 in which a plurality of sheaves are arranged in the width direction are provided at the rotating end portion 20B of the mast 20 and the rear end portion of the upper rotating body 12, respectively, and are pulled out from the boom hoisting winch 30. The boom hoisting rope 38 is laid between the sheave blocks 40 and 42. Accordingly, when the boom hoisting winch 30 winds or unwinds the boom hoisting rope 38, the distance between the two sheave blocks 40 and 42 changes, whereby the mast 20 and the boom 14 interlocking therewith are raised and lowered. Rotate in the direction.

  The jib hoisting winch 32 winds and pays out the jib hoisting rope 44. Then, the jib hoisting rope 44 is routed so that the upper strut 22 is rotated by this winding or feeding. Specifically, a guide sheave 46 is provided at a longitudinally intermediate portion of the lower strut 21, and a plurality of sheaves are arranged in the width direction at the distal end 21 B of the lower strut 21 and the distal end 22 B of the upper strut 22, respectively. Spreaders 47 and 48 (sheave blocks) are provided. The jib hoisting rope 44 pulled out from the jib hoisting winch 32 is hung on a guide sheave 46 and is hung between spreaders 47 and 48. Therefore, when the jib hoisting winch 32 winds or unwinds the jib hoisting rope 44, the distance between the two spreaders 47 and 48 is changed, and the upper strut 22 and the jib 17 associated therewith are rotated in the hoisting direction.

  The main winding winch 34 hoists and lowers the suspended load by the main winding rope 50. With respect to the main winding, guide sheaves 52, 53, and 54 for main winding are provided at a portion near the base end portion 21A of the lower strut 21, a portion near the base end portion 22A of the upper strut 22, and a tip portion 17B of the jib 17, respectively. It is provided rotatably. Further, a jib point sheave 56 is provided at a position adjacent to the main winding guide sheave 54 (the end portion 17B of the jib 17). The main winding rope 50 pulled out from the main winding winch 34 is hung on the main winding guide sheaves 52, 53, 54 in order, and has a jib point sheave 56 and a hook sheave provided on a main hook 57 for hanging loads. 58 and between. Therefore, when the main winding winch 34 winds or unwinds the main winding rope 50, the distance between the sheaves 56 and 58 changes, and the main hook 57 is raised and lowered.

  Similarly, the auxiliary winch 36 raises and lowers the suspended load by the auxiliary rope 60. For this auxiliary winding, auxiliary winding guide sheaves 62, 63, 64 are rotatably provided coaxially with the main winding guide sheaves 52, 53, 54, respectively. A roller 17R (auxiliary sheave) is rotatably provided at a position adjacent to the auxiliary winding guide sheave 64 (the tip 17B of the jib 17). An auxiliary rope 60 is wrapped around the auxiliary sheave. That is, the auxiliary rope 60 pulled out from the auxiliary winch 36 is sequentially hung on the auxiliary guide sheaves 62, 63, and 64 and hangs down from the auxiliary sheave. Therefore, when the auxiliary winding winch 36 winds or unwinds the auxiliary winding rope 60, the auxiliary hook for a suspended load (not shown) connected to the end of the auxiliary winding rope 60 is wound up or down.

  The notification device 110 shown in FIG. 2 is a device for notifying an operator of information on the front-back balance of the crane 10 based on the detection signal output by the strain detection unit 90. The notification device 110 has, for example, at least one of a sound emitting unit for emitting sound, a light emitting unit for emitting light, and a display unit for displaying characters, figures, and the like. The notification device 110 is arranged at a place where the operator can easily recognize the information, specifically, for example, at the cab 12A of the upper swing body 12.

  The sound generator has a function of emitting a sound that can be recognized by an operator through hearing. For example, the sound generator has a not-shown alarm buzzer, speaker, and the like. The light emitting unit has a function of emitting light that can be recognized by an operator through visual perception. For example, the light emitting section has a not-shown indicator light, rotating light, signal light, and the like. The display unit has a function of displaying characters, figures, and the like that can be visually recognized by an operator. For example, the display unit has a display (not shown).

  The controller 100 includes a central processing unit (CPU), a ROM for storing various control programs, a RAM used as a work area of the CPU, and the like. As illustrated in FIG. 2, the controller 100 includes a calculation unit 101 and a notification control unit 102 as functions. The calculation unit 101 is for calculating a moment in the direction in which the crane 10 tends to fall in the first direction D1 based on the detection signal output by the strain detection unit 90. The notification control unit 102 controls the notification device 110 to notify the operator of information on the front-back balance of the crane 10 based on the detection signal output from the strain detection unit 90.

[Lower traveling body]
FIG. 3 is a plan view showing the lower traveling body 11 of the crane 10 in FIG. 1, and FIG. 4 is a side view showing the lower traveling body 11. FIG. 5 is a side view showing the crawler frame 1 constituting the lower traveling body 11 of the crane 10 in FIG. FIG. 6 is a side view when the tip of the crawler frame 1 in the right crawler traveling device 3 in FIG. 3 is viewed in the direction of the arrow VI.

  As shown in FIGS. 3 and 4, the lower traveling body 11 is a crawler type, and includes a pair of crawler traveling devices 3 and 3, a revolving bearing 2 a to which an upper revolving superstructure 12 is attached, and the pair of crawler traveling devices 3. , 3 connected to each other and supporting a swing bearing 2a. The pair of crawler traveling devices 3 and 3 are configured by a first crawler traveling device 3 and a second crawler traveling device 3.

  The frame 2 includes a car body 2d that supports the slewing bearing 2a below the slewing bearing 2a, a front axle 2b that extends in the left and right direction in front of the car body 2d, and a rear part that extends in the left and right direction behind the car body 2d. An axle 2c. The first crawler traveling device 3 is attached to one end (right end) of the front axle 2b and one end (right end) of the rear axle 2c, and the other end (left end) of the front axle 2b and the other end of the rear axle 2c ( The second crawler traveling device 3 is attached to the left end).

  The first crawler traveling device 3 and the second crawler traveling device 3 have the same structure except that the arrangement of a plurality of components is reversed left and right. These crawler traveling devices 3 extend in the front-rear direction and are arranged at intervals in the left-right direction. Each crawler traveling device 3 includes a crawler frame 1, a pair of wheels 4a and 4c (a first wheel 4a and a second wheel 4c), a driving mechanism 4b, a crawler 7, a plurality of upper rollers 5, and a plurality of lower rollers. And a roller 6.

  The drive mechanism 4b includes a hydraulic motor (running motor) (not shown) and a running speed reducer. The crawler 7 is configured by connecting a number of shoes. The crawler 7 is a member that is supported by the pair of wheels 4a, 4c in an endless (ring-like) manner so as to be able to move around by being bridged between the pair of wheels 4a, 4c. In the present embodiment, the first wheel 4a is constituted by a drive tumbler 4a, and the second wheel 4c is constituted by an idler 4c.

As shown in FIG. 5, the crawler frame 1 has a shape extending in the front-rear direction. The crawler frame 1 includes a frame main body 1A and a tumbler bracket 1B. The frame main body 1A has a shape extending in the front-rear direction , and has a base end 1A1 as a rear end and a distal end 1A2 as a front end. The tumbler bracket 1B has a proximal end 1B1 (rear end) connected to the distal end 1A2 of the frame main body 1A, and a distal end 1B2 which is a front end. The portion 1B2 extends in the front-rear direction. The proximal end 1B1 of the tumbler bracket 1B is joined to the distal end 1A2 of the frame main body 1A using a joining means such as welding. The tumbler bracket 1B supports the drive tumbler 4a and the drive mechanism 4b.

  As shown in FIGS. 3, 5, and 6, the tumbler bracket 1B has a bracket body P1 and an outer peripheral portion P2. The bracket body P1 is a plate-like portion substantially orthogonal to the rotation axis CB of the drive tumbler 4a, and is a portion facing the drive mechanism 4b in the left-right direction. The outer peripheral portion P2 is a plate-like portion substantially parallel to the rotation axis CB and extends along the outer periphery of the bracket main body P1. The outer peripheral portion P2 covers part or all of the periphery of the drive mechanism 4b.

  The drive tumbler 4a is rotatably supported by a tumbler bracket 1B located at the tip of the crawler frame 1. The drive tumbler 4a is a wheel that is driven by the rotational force transmitted from the traveling motor to the traveling reduction gear to drive the crawler 7. The idler 4c is rotatably supported at the base end of the crawler frame 1 (base end 1A1 of the frame main body 1A). The idler 4c is a wheel that guides the crawler 7 on the opposite side of the drive tumbler 4a in the front-rear direction.

  The plurality of upper rollers 5 are rotatably supported at the upper part of the crawler frame 1, respectively. The plurality of upper rollers 5 are arranged between the drive tumbler 4a and the idler 4c at an interval in the front-rear direction to guide the crawler 7.

  The plurality of lower rollers 6 are rotatably supported below the crawler frame 1. The plurality of lower rollers 6 are disposed between the drive tumbler 4a and the idler 4c at an interval in the front-rear direction to guide the crawler 7. Hereinafter, one of the plurality of lower rollers 6 that is closest to the drive tumbler 4a (first wheel 4a) is referred to as a first lower roller 6A.

[Strain detector]
The strain detector 90 is for detecting information necessary for safely raising and lowering the boom 14 during the assembling operation and the disassembling operation of the crane 10. Specifically, the strain detecting section 90 is for detecting a strain generated in the crawler frame 1 in the standing operation and the falling operation. The strain detector 90 is configured to detect a strain generated in the crawler frame 1 and corresponding to a moment in a direction in which the crane 10 is tilted in the first direction D1. The standing operation is an operation for increasing the inclination angle of the boom 14 with respect to the ground, and the falling operation is an operation for decreasing the inclination angle.

  In the present embodiment, the crane 10 includes a strain detector 90 (first strain detector 90) capable of detecting a strain generated in the crawler frame 1 (first crawler frame 1) of the first crawler traveling device 3, and a second crawler A strain detecting section 90 (second strain detecting section 90) capable of detecting a strain generated in the crawler frame 1 (second crawler frame 1) of the traveling device 3; The first strain detecting section 90 and the second strain detecting section 90 have the same structure, and the positions provided on the corresponding crawler frames 1 are also the same. Therefore, the following mainly describes one of the strain detecting sections 90.

  As shown in FIGS. 3 and 4, the strain detection unit 90 is configured such that, in the corresponding crawler frame 1, the position in the front-rear direction is between the rotation axis CB of the drive tumbler 4a and the rotation axis CA of the first lower roller 6A. It is configured to be able to detect a strain generated in a portion included in the range R.

  The strain detection unit 90 is configured by one or a plurality of devices for detecting the strain of the crawler frame 1. As the device, for example, a strain gauge such as a metal strain gauge and a semiconductor strain gauge can be used. The strain gauge is attached to the crawler frame 1 by a method such as attaching it to the surface. However, the device that constitutes the strain detection unit 90 is not limited to the strain gauge, and another device that can detect the strain of the crawler frame 1 can be used. Examples of the other device include a load cell such as a pin-type load cell.

  The metal strain gauge has, for example, a structure in which a metal resistor (metal foil) laid out in a zigzag shape is mounted on a thin insulator, and detects a change in electric resistance due to deformation of the resistor. The change in the measured electric resistance is converted into the amount of strain of the crawler frame 1. The semiconductor strain gauge is, for example, a strain gauge using a piezoresistance effect in which the electrical resistivity of a semiconductor changes due to stress.

  As shown in FIGS. 5 and 6, in the present embodiment, the strain detector 90 is provided at the base end 1B1 of the tumbler bracket 1B of each crawler frame 1. Each of the strain detectors 90 includes a plurality of strain gauges (first strain gauge 90A, second strain gauge 90B in the illustrated example).

  As shown in FIG. 6, the first strain gauge 90 </ b> A is provided at an upper portion at the tip of the crawler frame 1, and the second strain gauge 90 </ b> B is provided at a lower portion at the tip of the crawler frame 1. Specifically, the first strain gauge 90A is provided at an upper portion of the base end 1B1 of the tumbler bracket 1B, and the second strain gauge 90B is provided at a lower portion of the base end 1B1 of the tumbler bracket 1B.

  In FIG. 6, a region T surrounded by a two-dot chain line is a region provided at the distal end 1A2 of the frame body 1A and the proximal end 1B1 of the tumbler bracket 1B, which are connected to each other. The region T is a connection portion between the frame main body 1A and the tumbler bracket 1B and an adjacent portion adjacent thereto. The region T includes a web portion S1 extending vertically in a plate shape, an upper flange portion S2 connected to the upper end of the web portion S1 and extending in a plate shape in the front-rear direction, and a lower end of the web portion S1 connected. And a lower flange portion S3 extending in a plate-like shape in the front-rear direction.

  The web part S1 is constituted by at least one of a part of the distal end part 1A2 of the frame main body 1A and a part of the base end part 1B1 of the tumbler bracket 1B. The upper flange portion S2 is constituted by a part of the distal end portion 1A2 of the frame main body 1A and a part of the base end portion 1B1 of the tumbler bracket 1B. The lower flange portion S3 is constituted by a part of the distal end portion 1A2 of the frame main body 1A and a part of the base end portion 1B1 of the tumbler bracket 1B.

  In the present embodiment, the first strain gauge 90A is provided at the base end 1B1 of the tumbler bracket 1B constituting the upper flange portion S2 (above the outer peripheral portion P2 of the tumbler bracket 1B described above). The second strain gauge 90B is provided on the base end 1B1 of the tumbler bracket 1B that constitutes the lower flange portion S3 (below the outer peripheral portion P2 of the tumbler bracket 1B described above).

  The strain detecting unit 90 detects a strain generated in the crawler frame 1 in the standing operation and the falling operation of the crane 10, and a detection signal detected by the strain detecting unit 90 is input to the controller 100 illustrated in FIG. Then, the calculation unit 101 calculates a moment in the direction in which the crane 10 is about to fall in the first direction D1 based on the detection signal. The notification control unit 102 controls the notification device 110 so that the information on the calculated moment (information on the balance before and after the crane 10) is notified to the operator by sound, light, characters, graphics, and the like.

[Assembly work and disassembly work]
Next, an assembly operation and a disassembly operation of the crane 10 according to the present embodiment will be described. 8 to 13 are side views schematically showing postures of the mobile crane shown in FIG. 1 during an assembling operation or a disassembling operation. FIG. 8 is a diagram when the undulating member is in a falling state, and FIGS. 9 and 10 are diagrams when the undulating member performs a rising operation or a falling operation in a state where the relative angle of the jib 17 to the boom 14 is large. is there. FIG. 11 is a diagram illustrating a state in which the balance position of the moment approaches the overturning fulcrum. FIG. 12 and FIG. 13 are diagrams illustrating a case where the up-and-down member performs a standing operation or a falling operation in a state where the relative angle of the jib 17 to the boom 14 is small. In FIGS. 8 to 13, only components necessary for explaining the moment received by the crane 10 are shown, and some components are not shown.

  As shown in FIGS. 10 and 13, in the crane 10, the undulating member including the boom 14 and the jib 17 extends in the first direction D <b> 1 with respect to the turning center C, and is opposite to the first direction D <b> 1. The counterweight 13 is arranged in the second direction D2. Hereinafter, the moment acting on the crane 10 will be mainly described with reference to the center of rotation C of the upper swing body 12.

  The moment (hereinafter, referred to as moment Mt) at which the crane 10 is inclined in the first direction D1 is mainly a moment (hereinafter, referred to as first moment Mf) generated mainly due to the weight and posture of the undulating member. It can be considered that it is determined mainly by the weight of the counterweight 13 and the moment generated by the weight of a part of the upper swing body 12 (hereinafter, referred to as a second moment Mb). That is, the moment Mt is obtained by subtracting the second moment Mb from the first moment Mf (Mt = Mf-Mb).

  As shown in FIGS. 10 and 13, when the loading amount of the counterweight 13 and the distance from the turning center C are not changed, the center of gravity Gb relating to the second moment Mb does not substantially change. It is constant. That is, assuming that the weight in which the weight of the counterweight 13 occupies a large proportion (the weight of the portion in the second direction D2 from the turning center C) is Wb, the second moment Mb is calculated from the weight Wb and the center of gravity position from the turning center C. It is represented by the product of the distance Lb to Gb (Mb = Wb × Lb).

  On the other hand, the distance L (for example, the distance L1 shown in FIG. 10 and the distance L2 shown in FIG. 13) from the turning center C to the center of gravity Gf of the undulating member changes depending on the posture of the undulating member including the boom 14 and the jib 17, One moment Mf varies according to the attitude of the undulating member. The center of gravity position Gf is mainly determined by the inclination angle of the boom 14 with respect to the ground and the relative angle of the jib 17 with respect to the boom 14. That is, when the weight of the undulating member is Wat, the first moment Mf is represented by the product of the weight Wat and the distance L (for example, the distance L1, the distance L2, etc.) from the turning center C to the center of gravity Gf (Mf). = Wat × L).

  For example, as shown in FIG. 13, the boom 14 is standing up to the upper revolving unit 12 to some extent until the inclination angle of the boom 14 with respect to the ground becomes relatively large, and the relative angle of the jib 17 with respect to the boom 14 is relatively large. In a small state (relative angle θ2), the first moment Mf and the second moment Mb around the turning center C may be substantially equal. In this substantially equal state, the moment Mt becomes substantially zero. Then, the weight of the crane 10 is substantially evenly distributed over the entire crawler 7 in the front-rear direction.

  As shown in FIG. 10, for example, as shown in FIG. 10, the boom 14 is laid down to a certain extent with respect to the upper swing body 12 until the inclination angle of the boom 14 with respect to the ground becomes relatively small, and In a state where the relative angle of the jib 17 with respect to 14 is relatively large (relative angle θ1), the center of gravity position Gf of the undulating member moves in the first direction D1, so that the first moment Mf around the turning center C increases. In such a biased state in which the moment is biased in the first direction D1, the moment Mt has a positive value larger than that in the substantially equal state (Mt = Mf−Mb> 0).

  Here, when the center of the moment for calculating the moment is moved in the front-back direction from the turning center C, and the front-back moment is calculated based on the center position after the movement, the position where the front-back moment becomes the same magnitude. Is defined as a “moment balance position”. As shown in FIGS. 10, 11, and 13, a portion S of the crawler frame 1 whose position in the front-rear direction corresponds to the rotation axis CB of the drive tumbler 4a is referred to as a fall fulcrum S.

  In the above-described substantially equal state (for example, the state shown in FIG. 13), the moment balance position P1 substantially coincides with the position of the turning center C. On the other hand, in the biased state (for example, the state shown in FIG. 10), the moment balance position P2 moves from the turning center C in the first direction D1. As shown in FIG. 10, even if the moment Mt becomes a positive value and the moment balance position moves from the turning center C to the position P2 in the first direction D1, the crane 10 does not immediately fall. That is, the biased state is a state in which the crawler frame 1 of the lower traveling body 11 resists the crane 10 from falling down in the first direction D1 due to the moment Mt.

  In the biased state as shown in FIG. 10, the moment Mt is zero (Mt = 0) at the moment balance position P2. The bending moment acting on the crawler frame 1 in this biased state mainly acts on the portion from the balancing position P2 to the overturning fulcrum S. In this unbalanced state, not the entire crawler frame 1 but the tip of the crawler frame 1 (the portion from the balance position P2 to the overturning fulcrum S) resists the moment Mt, and the bending rigidity of the tip of the crawler frame 1 This prevents the crane 10 from overturning and maintains the posture.

  For example, as shown in FIG. 11, when the center of gravity Gf of the undulating member moves further in the first direction D1 than the position shown in FIG. 13 and immediately before the crane 10 falls, the moment balance position P3 is set to the falling fulcrum S. And almost match. In the state immediately before the fall, each of the tip portions of the pair of crawler frames 1 receives almost all of the moment Mt. Note that a circular arrow Mr in FIG. 11 indicates a state where the tip of the crawler frame 1 is opposed to the moment Mt.

  Therefore, the distortion of the tip of the crawler frame 1 according to various states such as the substantially uniform state shown in FIG. 10, the biased state shown in FIG. 13, and the state immediately before falling shown in FIG. 11 is detected, and based on the detected distortion. If the moment received by the tip of the crawler frame 1 can be obtained, various states that the crane 10 can take can be determined.

  In the present embodiment, by providing the strain detection unit 90 at the tip of the crawler frame 1, that is, at a portion within the above-described range R, it is possible to effectively detect the strain generated at the tip of the crawler frame 1 in the above-described biased state. Thereby, it is possible to obtain an index of the state of the balance of the crane 10 in the front-rear direction.

  In the present embodiment, as described above, since information on the strain generated at the tip end of the crawler frame 1 detected by the strain detection unit 90 can be obtained, the assembly work of the crane 10 can be performed without an operator performing a complicated work. In addition, it is possible to detect information relating to the state of the crane 10 necessary for safely raising and lowering the raising and lowering member in the disassembling operation. Then, the detected information is used for the crane 10 to safely stand up and fall down. Specifically, it is as follows.

  In the assembling work for assembling the crane 10, as shown in FIG. 8, the boom 14 and the jib 17 are attached to the upper revolving unit 12 in a state where the boom 14 and the jib 17 are laid down in a posture substantially parallel to the ground GR (a laid-down state). Then, when performing the suspending operation, the posture of the boom 14 is changed from the lying state to the standing state (the state shown in FIG. 1) by the standing operation in which the inclination angle of the boom 14 with respect to the ground GR gradually increases.

  When displacing the up-and-down member from the down state to the upright state as described above, first, the inclination angle of the boom 14 is gradually increased in a state in which the roller 17R provided at the tip 17B of the jib 17 is in contact with the ground GR. In this operation, the relative angle of the jib 17 to the boom 14 gradually decreases.

  For example, when the relative angle becomes the angle θ1 as shown in FIG. 9 and the inclination angle of the boom 14 is further increased while maintaining the relative angle at the angle θ1 as shown in FIG. Since the roller 17R of 17B moves away from the ground GR, a moment Mf acts on the crane 10.

  At this time, the notification control unit 102 of the controller 100 controls the notification device 110, so that information on the front and rear balance of the crane 10 based on the detection signal output from the strain detection unit 90 is transmitted to the operator via the notification device 110. Be informed. Thus, the operator can obtain information on the front-back balance of the crane 10 through the notification device 110. For example, when the operator recognizes that the state of the crane 10 shown in FIG. 10 is unstable, the operator reduces the inclination angle of the boom 14 again, and for example, as shown in FIG. 17R is grounded. Then, the operator gradually increases the inclination angle of the boom 14 in a state where the roller 17R provided at the tip 17B of the jib 17 is in contact with the ground GR. In this operation, the relative angle of the jib 17 to the boom 14 gradually decreases (for example, the state shown in FIG. 12).

  For example, when the relative angle becomes the angle θ2 as shown in FIG. 12 and the inclination angle of the boom 14 is further increased while maintaining the relative angle at the angle θ2 as shown in FIG. Since the roller 17R of 17B moves away from the ground GR, a moment Mf acts on the crane 10. Since the moment balance position P1 at this time is located near the turning center C, the up-and-down member of the crane 10 can be safely raised.

  The disassembling operation for disassembling the crane 10 is performed safely by performing the reverse operation of the above-described assembling operation.

[Calculation method of moment]
Hereinafter, a method of calculating the moment acting on the tip of the crawler frame 1 will be specifically described.

  As shown in FIG. 6 described above, in the present embodiment, the distal end portion 1A2 of the frame main body 1A and the base end portion 1B1 of the tumbler bracket 1B, that is, the connection portion between the frame main body 1A and the tumbler bracket 1B and the connection portion The adjacent portion adjacent in the front-rear direction has a structure including an I-shaped (H-shaped) cross-sectional shape constituted by the web portion S1, the upper flange portion S2, and the lower flange portion S3.

  When the pair of crawler frames 1 is subjected to a bending load in the vertical direction when each of the pair of crawler frames 1 undergoes bending deformation when the up-and-down member performs the erecting operation and the falling-down operation, a bending deformation occurs at each of the crawler frame 1. The upper part of the neutral plane (neutral axis) is compressed and shrunk, and the lower part of the neutral plane is stretched and stretched.

  The upper and lower strains of each crawler frame 1 increase in proportion to the distance from the neutral plane. In the cross-sectional structure of the I-type (H-type), since the upper and lower flange portions S2 and S3 are located at positions where the distance from the neutral surface is relatively large, a relatively large strain (bending stress) is generated in the upper flange portion S2 and the lower flange portion S3. ) Occurs. Therefore, by providing the strain detecting section 90 in the upper flange portion S2 and the lower flange portion S3 as in the present embodiment, a relatively large strain can be detected.

  Here, the strain generated in the upper flange portion S2 is ε1, and the strain generated in the lower flange portion S3 is ε2. The distance from the neutral plane at the tip of each crawler frame 1 to the first strain gauge 90A is r1, and the distance from the neutral plane to the second strain gauge 90B is r2. Further, let I be the second moment of area of the section for measuring the strain, and let E be the longitudinal modulus of elasticity. Further, among the stresses generated by only the bending moment at the tip end of each crawler frame 1, the upper stress is σmt and the lower stress is σmc.

  The neutral plane (neutral axis) of the bending deformation at the tip of the crawler frame 1 is not always located at the center in the vertical direction at the tip. Therefore, the upper stress σmt and the lower stress σmc may be different. In such a case, the ratio of the upper stress σmt to the lower stress σmc (σmt: σmc) is the same as the ratio of the distance from the neutral plane (r1: r2) (σmt: σmc = r1: r2).

  The crawler 7 is wound around the crawler frame 1 so as not to be loosened. For this reason, the crawler frame 1 receives a compressive force σn (axial force) in the front-rear direction. The calculation method of the moment in consideration of the above premise is as follows.

  FIG. 7 is a diagram schematically illustrating a stress distribution generated in a cross section of a measurement target of strain at the tip end portion (the tumbler bracket 1B in the present embodiment) of the crawler frame 1. As shown in FIG. 7, the stress distribution is obtained by the sum of the stress (σmt, σmc) caused by the bending moment and the above-described compression force σn.

  Therefore, the equation for calculating the bending stress σmt necessary for obtaining the moment M is as follows:

  E × ε1−E × ε2 = (σmt + σn) − (− σmc + σn) = σmt + σmc = σmt (1 + r2 / r1) (1)

  From the above equation (1), the following equation (2) is obtained.

  σmt = E (ε1−ε2) / (1 + r2 / r1) (2)

  Therefore, the moment M applied to the tip of the crawler frame 1 is expressed by the following equation (3).

  M = E × σmt × I / r1 (3)

  Since the crane 10 includes the pair of crawler frames 1, the overturning moment Mt is given by the following equation (4), where MR and ML are the moments obtained from the strains at the tip portions of the right and left crawler frames 1. Become.

  Mt = MR + ML (4)

  The moment Mt calculated as described above is calculated by the calculation unit 101 of the controller 100 based on the detection signal input from the strain detection unit 90. As a result, a moment Mt that causes the crane 10 to overturn is obtained. The frequency of detection by the strain detection unit 90 and the frequency of calculation by the calculation unit 101 are not particularly limited. The detection by the strain detection unit 90 and the calculation by the calculation unit 101 may be performed, for example, at every preset time, or may be performed continuously (always).

  When the compression force σn (axial force) does not need to be considered, the moment M is expressed by the following equation (5).

  M = E × I (| ε1 / r1 | + | ε2 / r2 |) / 2 (5)

[Modification]
FIGS. 14 to 16 are side views when the tip of the crawler frame 1 is viewed in the direction of arrow VI in FIG. 3, and FIG. 14 is a view showing a first modification of the embodiment. FIG. 15 is a diagram illustrating a second modification of the embodiment, and FIG. 16 is a diagram illustrating a third modification of the embodiment.

  In the modified examples 1 to 3 shown in FIGS. 14 to 16, in the crawler frame 1, the strain detection unit 90 has a position in the front-rear direction between the rotation axis CB of the drive tumbler 4 a and the rotation axis CA of the first lower roller 6 </ b> A. This is the same as the embodiment shown in FIG. 6 in that the strain generated in a portion included in the range R can be detected. Further, Modification Examples 1 to 3 are that the first strain gauge 90A is provided on the upper portion of the crawler frame 1 and the second strain gauge 90B is provided on the lower portion of the crawler frame 1, and the first embodiment shown in FIG. Is the same as

  On the other hand, the modified examples 1 to 3 are different from the embodiment shown in FIG. Specifically, it is as follows.

  In the first modification shown in FIG. 14, the first strain gauge 90A and the second strain gauge 90B are provided on a web portion S1 extending in a vertical plate shape. In Modification Example 2 shown in FIG. 15, the first strain gauge 90A is provided so as to straddle the web portion S1 and the upper flange portion S2, and the second strain gauge 90B is provided so as to straddle the web portion S1 and the lower flange portion S3. Is provided.

  In Modification Example 3 shown in FIG. 16, the first strain gauge 90A and the second strain gauge 90B are provided at the distal end 1A2 of the frame main body 1A. Specifically, in the third modification, the first strain gauge 90A is provided at the distal end portion 1A2 of the frame main body 1A constituting the upper flange portion S2. The second strain gauge 90B is provided at the distal end 1A2 of the frame main body 1A constituting the lower flange portion S3.

  FIG. 17 is a perspective view schematically showing Modification 4 of the embodiment. In Modification Example 4 shown in FIG. 17, the crawler frame 1 further includes a measurement support 200 (deformation member) for attaching a strain gauge (strain detection unit). The measurement abutment 200 can detect the strain generated in the crawler frame 1 in a state where the distal end portion 14B of the boom 14 is located at a position deviated from the base end portion 14A of the boom 14 in the first direction D1 in the front-rear direction. Is located in the position. That is, the measurement abutment 200 is a portion of the crawler frame 1 whose position in the front-rear direction is included in a range between the rotation axis CB of the drive tumbler 4a and the rotation axis CA of the first lower roller 6A (see FIG. 4). It is provided in.

  For example, the measurement abutment 200 can be disposed in the crawler frame 1 at a position where the strain gauges 90A and 90B are provided in FIGS. 6, 14, 15, and 16, The site where the 200 is arranged is not limited to the above site. In the specific example shown in FIG. 17, the measurement abutment 200 is arranged in the same portion as the portion provided with the strain gauges 90A and 90B in the second modification shown in FIG. Specifically, it is as follows.

  As shown in FIG. 17, the measurement abutment 200 is provided so as to straddle the web portion S1 and the upper flange portion S2. In other words, the measurement abutment 200 is arranged at a corner formed by the web portion S1 and the upper flange portion S2.

  The measurement abutment 200 has a first surface 200A, a second surface 200B, and a holding surface 200C. The first surface 200A is a surface that is arranged to face the web portion S1 and is connected to the web portion S1. The second surface 200B is a surface that is arranged to face the upper flange portion S2 and is connected to the upper flange portion S2. The holding surface 200C is a surface that connects the edge of the first surface 200A and the edge of the second surface 200B, and that holds the strain gauge 90A. In the specific example shown in FIG. 17, the holding surface 200C is inclined so as to be located upward as it goes forward, and has an inclined surface that holds the strain gauge 90A. In the specific example shown in FIG. 17, the inclined surface is formed of an arcuate curved surface (concave curved surface), but may be formed of a flat surface or a convex curved surface. Further, in the specific example shown in FIG. 17, the measurement abutment 200 has a substantially L shape, but the shape of the measurement abutment 200 is not limited to the substantially L shape.

  The measurement abutment 200 is not only disposed at the corner formed by the web portion S1 and the upper flange portion S2 as described above, but also formed by the corner portion formed by the web portion S1 and the lower flange portion S3. Are also located. Then, when the up-and-down member performs the upright operation and the falling operation, a bending moment is applied to the crawler frame 1, and the tumbler bracket 1B and the frame body 1A undergo bending deformation. As a result, the holding surface 200C of the upper measurement support 200 is distorted in the direction in which it is pulled and extended. In addition, the holding surface of the lower measurement abutment is distorted in the direction of being compressed and contracted. Therefore, the strain for calculating the bending moment can be obtained by installing the strain gauge along the holding surface 200C. When the holding surface 200C is an arc-shaped curved surface, the magnitude of the strain can be adjusted by changing the radius of curvature of the arc.

[Other Modifications]
The crane 10 according to the embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the strain detection unit 90 is configured by a plurality of strain gauges, but may be configured by a single strain gauge.

  Further, in the above embodiment, the undulating member includes the jib 17, but the present invention can be applied to a crane having no jib.

  In the embodiment, the first direction is a direction from the center of the crawler frame 1 toward the tumbler bracket 1B in the front-rear direction. However, the present invention is not limited to this. The direction may be toward the opposite side to the bracket 1B. In the above-described embodiment, the first wheel is the drive tumbler 4a, but is not limited thereto, and may be an idler 4c.

  In the above-described embodiment, the strain detection unit 90 is disposed at the end of the crawler frame 1 where the tumbler bracket 1B is provided, but the end (the idler 4c is opposite to the end). (Attached end). Further, the strain detectors 90 may be provided at both ends of the crawler frame 1. When the strain detecting sections 90 are provided at both ends of the crawler frame 1 as described above, the strain generated in the crawler frame 1 in relation to the overturning moment can be obtained regardless of whether the undulating member is undulating. Can be detected.

  Further, in the above-described embodiment, the strain detection units 90 are provided on both of the pair of crawler frames 1, but the strain detection units 90 may be provided only on one of the crawler frames 1.

  The crane 10 according to the embodiment includes the strain detection unit 90 that can detect information necessary for safely raising and lowering the undulating member in the assembling operation and the disassembling operation of the crane 10; The information detected by the strain detection unit 90 can be used for safely raising and lowering the undulating member in a hanging operation other than the assembling operation and the disassembling operation. Specifically, the strain detection unit 90 detects a strain generated in a portion of at least one crawler frame 1 that is included in a range between the rotation axis CB of the first wheel 4a and the rotation axis CA of the first lower roller 6A. Is detected. Then, the detected strain of the above-described portion determines a state of the crane 10 such as a stable state in which the front and rear balance of the crane 10 is balanced and an unstable state approaching to fall in the first direction D1 in the lifting operation. It is an index for (guessing). Therefore, in the hanging operation, the strain detected by the strain detecting section 90 is used as an index for causing the up-and-down member to stand up and down, thereby improving the safety of the hanging operation.

DESCRIPTION OF SYMBOLS 1 Crawler frame 1A Frame main body 1A1 Base end of frame main body 1A2 Tip of frame main body 1B Tumbler bracket 1B1 Base end of tumbler bracket 1B2 Tip of tumbler bracket 4a Drive tumbler (first wheel)
6 Lower Roller 6A First Lower Roller 7 Crawler 10 Mobile Crane 11 Lower Traveling Body 12 Upper Revolving Structure 14 Boom 90 Strain Detector 90A, 90B Strain Gauge 100 Controller 101 Operation Unit 102 Notification Control Unit 110 Reporting Device CA First Lower Roller Rotation axis of CB Rotation axis of drive tumbler (Rotation axis of 1st wheel)
D1 First direction of front-rear direction GR Ground R Range between the rotation axis of the first wheel and the rotation axis of the first lower roller S1 Web part S2 Upper flange part S3 Lower flange part

Claims (6)

A pair of crawler frames extending in the front-rear direction and arranged at intervals in the left-right direction, and rotatably supported at ends of the crawler frames located in a first direction that is one of the front-rear directions. A second wheel rotatably supported at an end of the one wheel and each crawler frame located in a second direction opposite to the first direction and endlessly supported by the first wheel and the second wheel. The crawler is rotatably supported at the lower part of each crawler frame and each crawler frame, and is disposed at an interval in the front-rear direction between the first wheel and the second wheel to guide the crawler. A lower traveling body having a plurality of lower rollers,
An upper revolving structure pivotably supported on the lower traveling structure,
An up-and-down member including a boom supported so as to be able to undulate on the upper rotating body,
A strain detection unit for detecting a strain generated in at least one crawler frame of the pair of crawler frames,
When the one closest to the first wheel among the plurality of lower rollers is a first lower roller, the strain detection unit is configured such that, in the at least one crawler frame, the position in the front-rear direction is the position of the first wheel. A mobile crane configured to detect a strain generated in a portion included in a range between a rotation axis and a rotation axis of the first lower roller. The at least one crawler frame has a frame main body extending in the front-rear direction and a base end connected to the front end of the frame main body in the first direction, and extends from the base end in the first direction. A tumbler bracket for supporting the first wheel,
The mobile crane according to claim 1, wherein the strain detector is configured to detect a strain generated at the base end of the tumbler bracket or the tip of the frame body. The distal end portion of the frame main body and the base end portion of the tumbler bracket connected to each other are connected to a web portion extending in a plate shape in an up-down direction, and an upper end of the web portion is connected to extend in a plate shape in the front-rear direction. An upper flange portion, a lower flange portion connected to the lower end of the web portion and extending in a plate-like manner in the front-rear direction, having a structure including:
The mobile crane according to claim 2, wherein the strain detection unit includes at least one of a first device that detects a strain of the upper flange portion and a second device that detects a strain of the lower flange portion.   4. The mobile crane according to claim 1, further comprising: a calculation unit configured to calculate a moment in a direction in which the mobile crane tends to fall in the first direction based on a detection signal output by the strain detection unit. 5. Mobile crane as described. The strain detector is a first strain detector for detecting a strain generated in a first crawler frame of the pair of crawler frames,
The mobile crane further includes a second strain detector for detecting a strain generated in the second crawler frame,
The second strain detecting unit is configured to detect a strain generated in a portion of the second crawler frame in which the position in the front-rear direction is included in a range between a rotation axis of the first wheel and a rotation axis of the first lower roller. The mobile crane according to any one of claims 1 to 4, wherein the mobile crane is configured to detect the following. The information processing device according to any one of claims 1 to 5, further comprising: a notifying device for notifying the operator of information on a front-rear balance in the mobile crane based on a detection signal output by the strain detection unit. Mobile crane as described.