JP7137121B2 - mobile crane - Google Patents

Description

The present invention relates to mobile cranes.

Conventionally, a mobile type equipped with a self-propellable undercarriage, an upper revolving body rotatably mounted on the lower carriage, and a hoisting member including a boom hoistably mounted on the upper revolving body. Cranes are known. The lifting operation of the mobile crane is performed with the boom erected from the upper revolving structure (standing state). Further, in the assembling work of assembling the crane, the boom is attached to the upper revolving structure in a state in which the boom is laid down in a posture substantially parallel to the ground (lopped state). When the lifting work is performed, the posture of the boom is changed from the lying state to the standing state by the standing motion in which the inclination angle of the boom with respect to the ground gradually increases. On the other hand, in the disassembly work of disassembling the crane, the attitude of the boom is changed from the upright state to the downed state by the falling down motion in which the inclination angle of the boom with respect to the ground gradually decreases.

In such a crane, when the angle of inclination of the boom with respect to the ground changes, the position of the center of gravity of the luffing member, including the boom, changes, which in turn changes the moment due to the weight and position of the center of gravity of the luffing member. To prevent overturning of the crane due to such moment changes, mobile cranes are equipped with moment limiters. In the hoisting work, when the overturning moment of the crane reaches a preset threshold due to a change in the tilt angle of the boom, the moment limiter issues an alarm or stops the operation of the crane. Safety is ensured by

On the other hand, the assembling work and the disassembling work are different from the lifting work in the following points because they involve a large undulating motion between the standing state and the lying state as described above. Since the moment limiter is basically a device related to the stability during the lifting work, the lifting capacity of the moment limiter is set within the working range assumed in the lifting work. On the other hand, the assembly work and the disassembly work are not only performed within the working range of the lifting work, but also when the boom is at a small angle with respect to the ground (the boom is laid down). It may be done outside the scope of work. In this way, the lifting capacity is not set in the moment limiter for a range other than the working range of the lifting work. Therefore, in the assembly work and the disassembly work, the boom angle is reduced in a state in which the moment limiter is stopped, or in a state in which the moment limiter is not stopped but the limiter generated in the moment limiter is released. is done. Therefore, in the assembly work and disassembly work, the crane operator is required to have experience and knowledge to determine whether the tilt angle of the boom is a safe angle. Various techniques have been proposed to improve safety in such assembly and disassembly work.

For example, Patent Literature 1 discloses a crane operation support device. In cranes equipped with this operation support device, the combination of the boom length and jib length of the front attachment (raising member) is stable when the front attachment is tilted with the relative angle between the boom and jib set as the first target angle. In the case of a combination that achieves the desired performance, the tilting operation of the front attachment is performed until the tip of the jib touches the ground while the relative angle of the jib to the boom is maintained at the first target angle. .

In the technique disclosed in Patent Document 1, an operator previously inputs various kinds of information such as information on the boom and jib and target values for the relative angle between the boom and 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 with a boom and a jib as in Patent Document 1, a crane with a boom but without a jib, and a crane with a strut or a lattice mast. As described above, in a crane, the type of luffing member is selected according to the required capacity and the type of work, and the length of the boom and the length of the jib are adjusted.

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

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is intended to safely raise and lower a hoisting member during assembling and disassembling operations of a crane without requiring an operator to perform complicated input work. The purpose is to provide a mobile crane that can detect information necessary for

(1) A mobile crane according to the present invention includes a lower traveling body having a first crawler traveling device and a second crawler traveling device spaced apart in the left-right direction, and a lower traveling body capable of turning on the lower traveling body. a supported upper revolving body; a hoisting member including a boom hoistably supported by the upper revolving body; a right support member and a left support member provided on the first crawler traveling device; A right support member and a left support member provided in two crawler traveling devices, and at least one strain detector provided in at least one support member among the four support members. Each crawler traveling device is rotatably supported by a crawler frame extending in the front-rear direction, and an end located in a first direction, which is one direction in the front-rear direction, of both ends of the crawler frame in the front-rear direction. a first wheel and a second wheel rotatably supported at an end located in a second direction opposite to the first direction among the both ends; and the first wheel and the second wheel and a crawler that is endlessly supported and movable in a circular motion. Each support member includes a beam and legs. The beam has a base end portion supported by the crawler frame and a tip end portion located in a first direction relative to the base end portion in the front-rear direction. The leg is supported by the tip of the beam and extends downward from the tip so that the lower end contacts the ground. The leg portion of the right support member is deviated in the first direction from the rotation axis of the first wheel and positioned to the right of the crawler frame, and the leg portion of the left support member The portion is located off the rotation axis of the first wheel in the first direction and to the left of the crawler frame. The at least one strain detector is configured to detect strain occurring in the beam in the at least one support member.

The present invention has been made by paying attention to the strain of a member caused by a moment in the direction in which the crane tends to fall in the first longitudinal direction during assembly and disassembly of the crane. Good detection enables safe operation during assembly and disassembly of cranes. Specifically, it is as follows.

In the mobile crane of the present invention, the tip portion of the boom is arranged at a position shifted in the first direction from the base end portion of the boom in the longitudinal direction. When the mobile crane is arranged in a posture extending in the first direction of the front-rear direction from the revolving structure, a moment is generated in a direction in which the mobile crane tends to fall in the first direction. Each leg of the left support member and the left support member receives an upward reaction force from the ground. This creates a bending moment (bending stress) in the beam supporting the leg, which results in strain in the beam. Therefore, the strain is correlated with the reaction force, that is, with the moment (moment in the direction in which the mobile crane tends to fall in the first direction). Further, when the hoisting member performs the standing motion and the lofting motion, the position of the center of gravity of the hoisting member fluctuates in the longitudinal direction, so the moment (moment in the direction in which the mobile crane tends to fall in the first direction) increases or decreases. , which also increases or decreases the strain on the beam. Therefore, the strain of the beam detected by the strain detector determines the state of the crane, such as a stable state in which the crane is balanced fore and aft and an unstable state approaching overturning in the first direction. (guessing) and the determination does not require information on the combination of boom length and jib length. Therefore, in the mobile crane of the present invention, the operator inputs information about the combination of the boom length and the jib length and information about the target value of the relative angle between the boom and the jib, like the operation support device of Patent Document 1 described above. Such complicated work becomes unnecessary.

Further, in the mobile crane of the present invention, since the legs of each supporting member are located in the first direction with respect to the rotation axis of the first wheel of the crawler traveling device, the moment (the mobile crane is in the first The reaction force that the leg receives from the ground increases when a moment in the direction that the leg is about to fall down occurs. As a result, a large bending moment also acts on the beams that support the legs, so that the beams can be strained greatly. That is, in the present invention, the generation of a moment in the direction in which the mobile crane tends to fall in the first direction causes a large strain correlated to the moment on the beam of the supporting member. Therefore, the strain detector can detect the strain occurring in the beam with high sensitivity.

Further, in the mobile crane of the present invention, each crawler traveling device is provided with a right support member and a left support member, and the leg portion of the right support member is positioned to the right of the crawler frame and the left The leg of the support member is positioned to the left of the crawler frame. Therefore, when the moment (moment in the direction in which the mobile crane tends to fall in the first direction) is generated, the right support member and the left support member move the crawler traveling device in a balanced manner on both left and right sides of the crawler traveling device. can support. If only one of the support member on the right side and the support member on the left side is provided in the crawler traveling device, when the moment is generated, the supporting member balances the crawler traveling device in the lateral direction. It becomes impossible to support it, and a torsional moment is likely to occur in the crawler traveling device. In the present invention, the generation of such a torsional moment can be suppressed, so that the influence of the torsional moment on the detection result by the strain detection section can be reduced.

As described above, in the mobile crane of the present invention, even if the operator does not perform complicated input work, the crane is required to safely raise and lower the hoisting member in the assembly work and disassembly work of the crane. Information about the state can be detected with high sensitivity. The detected information is used for the crane to safely stand up and lay down.

(2) In the mobile crane, the legs include a cylinder body supported by the tip of the beam and extending downward from the tip, and a rod vertically slidable with respect to the cylinder body. and preferably includes

In this aspect, even if there is a height difference between the ground surface with which the crawler traveling device is in contact and the ground surface with which the lower ends of the legs of the support members are in contact, the position of the rod with respect to the cylinder body is adjusted. , the lower ends of the legs can be reliably grounded, and the posture of the beam of the support member can be set to a proper state for strain detection.

(3) In the mobile crane, the strain detector includes a first device that detects strain occurring in the upper portion of the beam and a second device that detects strain occurring in the lower portion of the beam. is preferred.

When the hoisting member is arranged in a posture extending in the first longitudinal direction from the upper revolving body, the beam receives a vertical bending load due to the moment. In such a case, the upper and lower portions of the beam, which are at greater distances from the neutral plane of the beam, experience greater strain. Therefore, in this aspect, the strain induced in the beam can be detected more sensitively by the first device and the second device capable of detecting the strain induced above and below the beam.

(4) The mobile crane may include a notification device for notifying the operator of information regarding the front-rear balance of the mobile crane based on the detection signal output by the strain detection unit. good.

In this aspect, the operator can obtain information about the front-to-rear balance of the crane through the notification device, so that the operator can operate the crane using the information as an index, thereby safely raising and lowering the crane. can be operated.

(5) The mobile crane further includes a computing section that computes a moment in a direction in which the mobile crane tends to fall in the first direction based on the detection signal output from the strain detecting section. good too.

In this aspect, the moment is calculated by the calculation section based on the detection signal from the strain detection section, thereby obtaining the moment that causes the crane to overturn. The calculated moment is used for safe operation by the mobile crane. 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 section and the calculation by the calculation section may be performed, for example, at preset time intervals, or continuously (always).

(6) In the mobile crane, it is preferable that at least a part of the beam is detachable from a mounting portion to which the at least part is mounted.

In this aspect, the at least part of the beam of the support member is attached to the mounting portion only when necessary in work such as crane assembly or disassembly, and the support member is removed when the support member is unnecessary, such as in hoisting work. The at least part of the beam can be detached from the mount. As a result, the support member is less likely to interfere with the lifting work, and the weight of the crane can be reduced by the weight of the removed member.

(7) In the mobile crane, the at least one strain detector is provided in one of the right support member and the left support member provided in the first crawler traveling device. A first strain detector configured to detect strain occurring in the beam, wherein the mobile crane is one of the right support member and the left support member provided in the second crawler traveling device It is preferable to further include a second strain detection section capable of detecting strain occurring in the beam in one supporting member.

In this aspect, since both the first crawler traveling device and the second crawler traveling device are provided with the strain detecting section, for example, when the hoisting member performs the standing motion and the falling motion, the left and right sides of the crane are displaced. Even if there is no balance between the left and right sides, the respective strain detectors detect information about the state of the crane according to the balance between the left and right sides. Therefore, compared to the case where the strain is detected by a single strain detector, the information about the crane condition necessary for safely raising and lowering the luffing members in the assembly and disassembly of the crane is more accurately obtained. can be detected.

According to the present invention, there is provided a mobile crane capable of detecting information necessary for safely raising and lowering a hoisting member during assembling and disassembling work of the crane without the operator having to perform complicated input work. can provide.

1 is a side view showing a mobile crane according to an embodiment of the present invention, showing a posture during lifting work, and a drawing when a hoisting member is in an upright state. FIG. It is a block diagram showing a functional configuration of a mobile crane according to the embodiment. FIG. 3 is a plan view showing a lower traveling body of the mobile crane according to the embodiment and a support member provided in a crawler traveling device of the lower traveling body; It is a side view which shows the undercarriage of the mobile crane which concerns on the said embodiment, and the support member provided in the crawler traveling apparatus of the said undercarriage. FIG. 4 is a cross-sectional view of the beam of the support member provided in the crawler traveling device of the lower traveling body shown in FIG. 3 taken along line VV; It is a side view which shows the front part of the undercarriage of the mobile crane which concerns on the said embodiment, and the support member provided in the crawler traveling apparatus of the said undercarriage. FIG. 4 is a plan view showing the front portion of the undercarriage of the mobile crane according to the embodiment and a support member provided in the crawler traveling device of the undercarriage; FIG. 2 is a side view schematically showing the attitude of the mobile crane of FIG. 1 during assembly work or disassembly work, in which the hoisting member is in a laid down state; FIG. 4 is a side view schematically showing the posture of the mobile crane of FIG. 1 during assembly or disassembly work, and is a view when the hoisting member performs a standing motion or a laying motion; FIG. 4 is a side view schematically showing the posture of the mobile crane of FIG. 1 during assembly or disassembly work, and is a view when the hoisting member performs a standing motion or a laying motion; FIG. 2 is a side view schematically showing the posture of the mobile crane in FIG. 1 during assembly or disassembly work, and shows a state in which the moment balance position approaches the overturning fulcrum; FIG. 4 is a side view schematically showing the posture of the mobile crane of FIG. 1 during assembly or disassembly work, and is a view when the hoisting member performs a standing motion or a laying motion; FIG. 4 is a side view schematically showing the posture of the mobile crane of FIG. 1 during assembly or disassembly work, and is a view when the hoisting member performs a standing motion or a laying motion; FIG. 4 is a diagram schematically showing a stress distribution occurring in a cross section of a strain measurement target in a beam of a support member; It is a top view which shows the undercarriage of the mobile crane which concerns on the modification 1 of the said embodiment, and the support member provided in the crawler traveling apparatus of the said undercarriage. FIG. 4 is a perspective view showing a crawler frame and a support member attached to the crawler frame in a mobile crane according to Modification 1 of the embodiment, with a part of the beam of the support member removed from the attachment portion; It is a figure which shows a state. FIG. 17 is a perspective view showing the crawler frame and support member shown in FIG. 16 , showing a state in which a part of the beam of the support member is attached to the attachment portion; FIG. 17 is a side view of the crawler frame and support member shown in FIG. 16 with a portion of the beam of the support member removed from the mounting portion; FIG. 17 is a side view of the crawler frame and support member shown in FIG. 16, showing a state in which a portion of the beam of the support member is attached to the attachment portion; It is a perspective view which shows the modification 2 of the said embodiment typically.

A mobile crane according to an embodiment of the present invention will be described below with reference to the drawings.

[Mobile Crane]
FIG. 1 is a side view showing a mobile crane 10 according to an embodiment, showing a posture during a lifting operation, in which the hoisting member is in an upright state. FIG. 2 is a block diagram showing the functional configuration of the mobile crane 10 of FIG. 1. As shown in FIG. The directions such as "up", "down", "front", "rear", "right", and "left" shown in the drawings indicate the structure and hoisting method of the mobile crane according to the embodiment of the present invention. It is shown for the convenience of explanation, and does not limit the moving direction, the mode of use, etc. of the mobile crane. Further, in this embodiment, as shown in FIG. 3, one of the front-rear directions is the first direction D1, and the other front-rear direction is the second direction D2.

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 able to turn about its axis, a hoisting member, and a mast 20. , a counterweight 13 mounted on the rear portion of the upper swing body 12, a plurality of support members 80, a plurality of strain detectors 90, a controller 100 (see FIG. 2), and a notification device 110. In this embodiment, the luffing members include boom 14 , jib 17 , upper struts 22 and lower struts 21 .

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

The boom body 15 includes a proximal side member 15A, one or a plurality of (two in the figure) intermediate members 15B and 15C, and a distal side member 15D. The proximal side member 15A is connected to the front portion of the upper rotating body 12 so as to be rotatable in the up-and-down direction. The intermediate members 15B and 15C are detachably connected in that order to the distal end of the proximal side member 15A. The tip side 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 portion 17A of the jib 17 is rotatably connected to a tip end portion 14B of the boom 14 . The rotation center axis of the jib 17 is parallel to the rotation center axis of the boom body 15 with respect to the upper swing body 12 . As shown in FIG. 1, the tip portion 17B of the jib 17 has a roller 17R that supports the jib 17 when the tip portion 17B contacts the ground and is rotatable on the ground.

An upper strut 22 and a lower strut 21 are provided for pivoting the jib 17 . The upper strut 22 is rotatably attached to the tip portion 14B of the boom 14 . The lower strut 21 is rotatably attached to the tip 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 tip portion 14B of the boom 14 .

A pair of left and right backstops 23 are provided on the upper swing body 12 . These backstops 23 come into contact with the left and right sides of the base end member 15A of the boom 14 when the boom 14 reaches the upright posture shown in FIG. It regulates being pushed backwards.

The lower strut 21 is held in a posture protruding from the tip portion 14B of the boom 14 toward the boom rising side (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 tip side member 15D and the 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 its tension.

The upper strut 22 is connected to the jib 17 so as to rotate with it. Specifically, a pair of left and right jib guy lines 28 are 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 driven to rotate by the rotation of the upper strut 22 .

The mast 20 has a base end 20A and a pivot end 20B. A base end portion 20A of the mast 20 is rotatably connected to the upper revolving body 12 . The pivot axis of the mast 20 is parallel to the pivot axis of the boom 14 and positioned just behind the pivot axis of the boom 14 . That is, the mast 20 is rotatable in the same direction as the boom 14 is raised and lowered. On the other hand, the rotating end portion 20B of the mast 20 is connected to the tip portion 14B of the boom 14 via a pair of left and right boom guylines 24 . This connection coordinates the rotation of the mast 20 and the rotation of the boom 14 .

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

The boom hoisting winch 30 winds up and lets out a boom hoisting rope 38 . The boom hoisting rope 38 is routed so that the mast 20 is rotated by this 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. A boom hoisting rope 38 is stretched between sheave blocks 40 and 42 . Therefore, when the boom hoisting winch 30 winds or feeds the boom hoisting rope 38, the distance between the sheave blocks 40 and 42 changes, thereby raising and lowering the mast 20 and the boom 14 interlocked therewith. direction.

The jib hoisting winch 32 winds up and lets out the jib hoisting rope 44 . The jib hoisting rope 44 is routed so that the upper strut 22 rotates due to this winding and feeding. Specifically, a guide sheave 46 is provided in the longitudinally intermediate portion of the lower strut 21, and a plurality of sheaves are arranged in the width direction at the distal end portion 21B of the lower strut 21 and the distal end portion 22B of the upper strut 22, respectively. Spreaders 47, 48 (sheave blocks) are provided. A jib hoisting rope 44 pulled out from the jib hoisting winch 32 is hung on a guide sheave 46 and stretched between spreaders 47 and 48 . Therefore, winding or unwinding of the jib hoisting rope 44 by the jib hoisting winch 32 changes the distance between the spreaders 47 and 48, and rotates the upper strut 22 and the jib 17 interlocked therewith in the hoisting direction.

The main hoisting winch 34 hoists and lowers the suspended load by the main hoisting rope 50 . For this main hoisting, main hoisting guide sheaves 52, 53, and 54 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 end portion 17B of the jib 17, respectively. It is rotatably provided. Furthermore, a jib point sheave 56 is provided at a position adjacent to the main hoisting guide sheave 54 (the leading end portion 17B of the jib 17). A main hoisting rope 50 pulled out from a main hoisting winch 34 is sequentially hung on main hoisting guide sheaves 52, 53, 54, and hook sheaves provided on a jib point sheave 56 and a main hook 57 for hoisting cargo. 58 and . Therefore, when the main hoisting winch 34 winds or unwinds the main hoisting rope 50, the distance between the sheaves 56, 58 changes and the main hook 57 is hoisted and lowered.

Similarly, the auxiliary hoisting winch 36 hoists and lowers the suspended load with the auxiliary hoisting rope 60 . As for the auxiliary winding, auxiliary winding guide sheaves 62, 63 and 64 are rotatably provided coaxially with the main winding guide sheaves 52, 53 and 54, respectively. A roller 17R (auxiliary sheave) is rotatably provided at a position adjacent to the auxiliary winding guide sheave 64 (front end portion 17B of the jib 17). An auxiliary winding rope 60 is wound around the auxiliary sheave. That is, the auxiliary hoisting rope 60 pulled out from the auxiliary hoisting winch 36 is sequentially hung on the auxiliary hoisting guide sheaves 62, 63, 64, and suspended from the auxiliary sheaves. Therefore, when the auxiliary hoisting winch 36 winds or feeds the auxiliary hoisting rope 60, the auxiliary hook (not shown) connected to the end of the auxiliary hoisting rope 60 is hoisted or lowered.

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

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

The controller 100 is composed of a central processing unit (CPU), a ROM that stores various control programs, a RAM that is used as a work area for the CPU, and the like. As shown 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 from the strain detection unit 90 . The notification control unit 102 controls the notification device 110 to notify the operator of information regarding the front-to-rear balance of the crane 10 based on the detection signal output by the strain detection unit 90 .

[Lower running body]
FIG. 3 is a plan view showing the lower traveling body 11 of the mobile crane 10 according to this embodiment and the support member 80 provided on the crawler traveling device 3 of the lower traveling body 11. FIG. FIG. 4 is a side view showing the undercarriage 11 and the support member 80, showing the state when the support member 80 is used.

As shown in FIGS. 3 and 4, the lower traveling body 11 is of a crawler type, and includes a pair of crawler traveling devices 3, 3, a revolving bearing 2a to which the upper rotating body 12 is attached, a pair of crawler traveling devices 3, 3 and a frame 2 that supports the swivel bearing 2a. The pair of crawler traveling devices 3, 3 is composed of a first crawler traveling device 3 and a second crawler traveling device 3 which are spaced apart in the left-right direction.

The frame 2 includes a car body 2d supporting the swivel bearing 2a below the swivel bearing 2a, a front axle 2b extending in the left-right direction in front of the car body 2d, and a rear part extending in the left-right direction behind the car body 2d. and an axle 2c. A 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 A 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 the plurality of constituent members is left-right reversed. Each crawler traveling device 3 has a shape extending in the front-rear 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 drive mechanism 4b, a crawler 7, a plurality of upper rollers 5, and a plurality of lower a roller 6;

The drive mechanism 4b includes a hydraulic motor (running motor) (not shown) and a running speed reducer. The crawler 7 is constructed by connecting a large number of shoes. The crawler 7 is a member that is supported endlessly (in a ring shape) by the pair of wheels 4a and 4c by being bridged between the pair of wheels 4a and 4c so as to be rotatably movable. In this embodiment, the first wheel 4a is configured by the drive tumbler 4a, and the second wheel 4c is configured by the idler 4c.

As shown in FIG. 6, the crawler frame 1 has a shape extending in the front-rear direction. The crawler frame 1 includes a frame body 1A and a tumbler bracket 1B.

The frame main body 1A has a shape extending in the front-rear direction. The frame main body 1A includes an upper plate portion 111 extending in the longitudinal direction of the frame main body 1A, a lower plate portion 112 disposed below the upper plate portion 111 with a gap therebetween and extending in the longitudinal direction. and a side plate portion 113 that connects the plate portion 111 and the lower plate portion 112 .

The tumbler bracket 1B has a base end connected to the tip of the frame main body 1A and extends from the base end in the front-rear first direction D1. A base end portion of the tumbler bracket 1B is joined to a front end portion of the frame main body 1A using joining means such as welding. The tumbler bracket 1B supports the drive tumbler 4a and the drive mechanism 4b.

The drive tumbler 4a is rotatably supported by the tumbler bracket 1B about its rotation axis CB. The drive tumbler 4a is a wheel that rotates and drives the crawler 7 by the rotational force transmitted from the travel motor to the travel speed reducer. The idler 4c is rotatably supported at the base end of the crawler frame 1 (the base end 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 longitudinal direction.

A plurality of upper rollers 5 are rotatably supported on the upper portion of the crawler frame 1 . A plurality of upper rollers 5 are arranged at intervals in the front-rear direction between the drive tumbler 4a and the idler 4c to guide the crawlers 7. As shown in FIG.

A plurality of lower rollers 6 are rotatably supported at the lower portion of the crawler frame 1 . A plurality of lower rollers 6 are arranged at intervals in the front-rear direction between the drive tumbler 4a and the idler 4c to guide the crawlers 7. As shown in FIG.

[Support member]
As shown in FIG. 3, in the present embodiment, the plurality of support members 80 include a right support member 80 and a left support member 80 provided in the first crawler travel device 3, and a second crawler travel device. 3 includes a right support member 80 and a left support member 80 .

As shown in FIGS. 3 and 4, each support member 80 includes a beam 81 and legs 82 . The beam 81 has a base end portion 8A supported by the crawler frame 1 and a tip end portion 8B positioned in the first direction D1 relative to the base end portion 8A in the front-rear direction. In this embodiment, each beam 81 extends linearly in plan view shown in FIG.

A base end portion 8A of each beam 81 is attached to the crawler frame 1, and each beam 81 extends in a direction inclined with respect to the first direction D1. Specifically, the base end portion 8A of each beam 81 is attached to a portion of the frame body 1A of the crawler frame 1 that is deviated from the front axle 2b in the first direction D1.

More specifically, the base end portion 8A of the beam 81 in the right support member 80 is attached to the right side portion of the frame main body 1A of the crawler frame 1, and the beam 81 extends from the right side portion in the first direction D1. It extends in a direction inclined to the right (diagonally forward to the right). The base end 8A of the beam 81 of the left support member 80 is attached to the left side of the frame body 1A of the crawler frame 1, and the beam 81 is inclined leftward from the left side with respect to the first direction D1. It extends in the direction (diagonally forward to the left).

The leg portion 82 is supported by the tip portion 8B of the beam 81 and extends downward from the tip portion 8B so that the lower end portion 85 contacts the ground. In this embodiment, the leg portion 82 is configured by a hydraulic cylinder. Specifically, the leg portion 82 includes a cylinder body 83 supported by the tip portion 8B of the beam 81 and extending downward from the tip portion 8B, and a rod 84 vertically slidable with respect to the cylinder body 83. including.

The leg portion 82 of each support member 80 is at a position deviated in the first direction D1 from the rotation axis CB of the drive tumbler 4a. Here, "the leg portion 82 is located at a position shifted in the first direction D1 with respect to the rotation axis CB of the drive tumbler 4a (first wheel)" means that the central axis CC of the leg portion 82 is aligned with the drive tumbler 4a (first wheel). 1 wheel) in a position deviated in the first direction D1 with respect to the rotation axis CB. In this embodiment, the central axis CC of the leg portion 82 is the central axis CC of the vertically extending hydraulic cylinder (the central axis CC of the rod 84).

The leg portion 82 of the right support member 80 (specifically, the central axis CC of the leg portion 82) is positioned to the right of the crawler frame 1, and the leg portion 82 of the left support member 80 (specifically, A center axis CC) of the leg portion 82 is positioned to the left of the crawler frame 1 .

FIG. 5 is a sectional view of the beam 81 of the support member 80 provided in the crawler traveling device 3 of the lower traveling body 11 shown in FIG. 3, taken along line VV. As shown in FIG. 5, the beam 81 of each support member has a structure in which the cross section orthogonal to the longitudinal direction of the beam 81 is closed. As shown in FIGS. 3 to 5, the beam 81 includes an upper plate portion 811 extending in the longitudinal direction of the beam 81, and an upper plate portion 811 spaced downwardly from the upper plate portion 811 and extending in the longitudinal direction. It has a lower plate portion 812 and a pair of side plate portions 813 and 814 each extending in the longitudinal direction. One side plate portion 813 connects the right ends of the upper plate portion 811 and the lower plate portion 812, and the other side plate portion 814 connects the right ends of the upper plate portion 811 and the lower plate portion 812. there is More specifically, the beam 81 further has a second top plate portion 815 . The second upper plate portion 815 is positioned between the upper plate portion 811 and the leg portion 82 and connects the upper plate portion 811 and the leg portion 82 . The second upper plate portion 815 is arranged so as to incline downward toward the tip portion 8B of the beam 81 .

A base end portion 8</b>A of the beam 81 is provided with a mounting portion for mounting the beam 81 to the crawler frame 1 . In this embodiment, the attached portion is composed of a through hole 811 a provided at the proximal end of the upper plate portion 811 and a through hole 812 a provided at the proximal end of the lower plate portion 812 . On the other hand, the frame main body 1A of the crawler frame 1 is provided with mounting portions. The mounting portion is composed of a through hole 111a provided in the upper plate portion 111 of the frame body 1A and a through hole 112a provided in the lower plate portion 112. As shown in FIG. A vertically extending pin 86 is inserted through the through-holes 811a and 812a forming the mounting portions and the through-holes 111a and 112a forming the mounting portions in alignment with each other. Thereby, the beam 81 is attached to the crawler frame 1 so as to be rotatable around the pin 86 .

In this embodiment, each support member 80 is configured to be detachable from the crawler frame 1 . That is, each support member 80 can be removed from the crawler frame 1 by removing the pin 86 described above from the through hole.

6 is a side view showing the front portion of the lower traveling body 11 and the supporting member 80, and FIG. 7 is a plan view showing the front portion of the lower traveling body 11 and the supporting member 80. As shown in FIG. 6 and 7 show the state when the support member 80 is not in use.

In this embodiment, as shown in FIGS. 3 and 4, when the support members 80 are used in the assembly work and disassembly work of the crane 10, each support member 80 is obliquely forward from the frame main body 1A of the crawler frame 1. arranged to extend. On the other hand, when the support members 80 are not used, each support member 80 can be accommodated in the accommodation space provided in the frame body 1A of the crawler frame 1 as shown in FIGS.

Specifically, in this embodiment, the accommodation space is formed by a concave portion defined by the upper plate portion 811 , the lower plate portion 112 and the side plate portion 113 . The leg portion 82 is connected to the distal end portion 8B of the beam 81 by a connecting member 87. As shown in FIG. The connecting member 87 is provided with a pin 87a. The leg portion 82 is attached to the connecting member 87 so as to be rotatable around the pin 87a. When each support member 80 is accommodated, the lower end 85 of the leg portion 82 is removed from the rod 84, and the beam 81 is rotated around the pin 86 while the leg portion 82 is rotated around the pin 87a. Thereby, the beam 81 and the leg portion 82 are housed in the housing space.

[Strain detector]
The strain detector 90 is for detecting information necessary for safely raising and lowering the boom 14 during assembly and disassembly of the crane 10 . Specifically, the strain detector 90 is for detecting strain occurring in the beam 81 of the support member 80 . The strain detector 90 is configured to be able to detect strain generated in the beam 81 of the support member 80 and corresponding to a moment tilting the crane 10 in the first direction D1. The standing operation is an operation for increasing the tilt angle of the boom 14 with respect to the ground, and the laying down operation is an operation for decreasing the tilt angle.

In this embodiment, the crane 10 includes multiple strain detectors 90 . Specifically, the crane 10 includes four strain detectors 90 provided on four support members 80 . Therefore, the strain produced in the beam 81 of each support member 80 can be detected. In this embodiment, the four strain detectors 90 have the same structure, and the positions provided on the corresponding crawler frames 1 are also the same as shown in FIG. Part 90 will be described in detail.

In this embodiment, the strain detector 90 is located at a portion of the beam 81 of the support member 80 between the base end portion 8A of the beam 81 supported by the crawler frame 1 and the center of the beam 81 in the longitudinal direction. It is configured to be able to detect the strain that occurs. However, the strain detector 90 is configured to be able to detect strain occurring in a portion of the beam 81 of the support member 80 between the tip portion 8B that supports the leg portion 82 and the center of the beam 81 in the longitudinal direction. Alternatively, it may be configured to detect strain occurring in the center of the beam 81 in the longitudinal direction.

The strain detector 90 is preferably provided at a portion of the beam 81 where strain is likely to occur. Thereby, the distortion of the beam 81 caused by the moment can be detected with high sensitivity. Examples of the portion where strain is likely to occur include the connection portion between the beam 81 and the crawler frame 1 or an adjacent portion adjacent to the connection portion, the connection portion between the beam 81 and the leg portion 82, or the adjacent portion adjacent to the connection portion. can be done.

The strain detector 90 is composed of one or more devices for detecting strain of the beam 81 . As the device, strain gauges such as metal strain gauges and semiconductor strain gauges can be used. The strain gauges are attached by a method such as sticking to the surface of the beam 81 . However, the device that constitutes the strain detector 90 is not limited to the strain gauge, and other devices that can detect the strain of the beam 81 can also be used. A load cell such as a pin type load cell can be exemplified as the other device.

A metal strain gauge has a structure in which, for example, a metal resistor (metal foil) laid out in a zigzag pattern on a thin insulator is attached, and detects changes in electrical resistance due to deformation of the resistor. The measured change in electrical resistance is converted to the amount of strain on the beam 81 . A semiconductor strain gauge is, for example, a strain gauge that utilizes the piezoresistive effect in which the electrical resistivity of a semiconductor changes with stress.

As shown in FIG. 5, in the present embodiment, the strain detector 90 is composed of a plurality of strain gauges (a first strain gauge 90A and a second strain gauge 90B in the figure). The first strain gauge 90A is provided on an upper plate portion 811 forming the upper portion of the beam 81, and the second strain gauge 90B is provided on the lower plate portion 812 forming the lower portion of the beam 81. As shown in FIG. These strain gauges 90A and 90B can detect the strain occurring in the upper portion of the beam 81 and the strain occurring in the lower portion of the beam 81. FIG.

In the present embodiment, the first strain gauge 90A is provided at the center of the upper plate portion 811 of the beam 81 in the width direction, but is not limited to this, and is located at a position shifted from the center in the width direction to one side in the width direction. may be provided in Similarly, the second strain gauge 90B is provided at the center in the width direction of the lower plate portion 812 of the beam 81, but is not limited to this, and is provided at a position shifted from the center in the width direction to one side in the width direction. may have been Although each strain gauge is attached to the outer surface of the beam 81 in this embodiment, it may be attached to the inner surface of the beam 81 .

The strain detector 90 detects the strain that occurs in the beam 81 of the support member 80 during the standing motion and the lofting motion of the crane 10, and the detection signal output by the strain detector 90 is input to the controller 100 shown in FIG. be done. Then, the calculation unit 101 calculates the moment in the direction in which the crane 10 tends to fall in the first direction D1 based on the detection signal. The notification control unit 102 controls the notification device 110 so that information regarding the calculated moment (information regarding the front-rear balance of the crane 10) is notified to the operator by means of sound, light, characters, graphics, or the like.

[Assembly work and disassembly work]
Next, assembly work and disassembly work of the crane 10 according to this embodiment will be described. 8 to 13 are side views schematically showing postures during assembly or disassembly of the mobile crane of FIG. 1. FIG. FIG. 8 is a diagram showing the hoisting member in the laid down state, and FIGS. 9 and 10 are diagrams showing the hoisting member raising or laying down in a state where the relative angle of the jib 17 to the boom 14 is large. be. FIG. 11 is a diagram showing a state in which the moment balance position approaches the tipping fulcrum. 12 and 13 are diagrams when the hoisting member is raised or lowered while the relative angle of the jib 17 to the boom 14 is small.

8 to 13, only constituent elements necessary for explaining the moment received by the crane 10 are illustrated, and illustration of some constituent elements is omitted. In addition, in the description of the moment below, the moment acting on the crane 10 when the support member 80 is not attached to the crawler frame 1 will be described.

As shown in FIGS. 10 and 13, in the crane 10, the hoisting member including the boom 14 and the jib 17 extends in the first direction D1 when the turning center C is used as a reference, and is opposite to the first direction D1. The counterweight 13 is arranged in the second direction D2 of the . Hereinafter, the moment acting on the crane 10 will be mainly described with reference to the turning center C of the upper turning body 12 .

The moment (hereinafter referred to as moment Mt) that causes the crane 10 to fall in the first direction D1 is a moment (hereinafter referred to as first moment Mf) generated mainly due to the weight and attitude of the hoisting member, It can be considered that it is mainly determined by the weight of the counterweight 13 and the moment (hereinafter referred to as the second moment Mb) generated due to the weight of a part of the upper revolving body 12 . 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 load of the counterweight 13 and the distance from the turning center C are not changed, the center-of-gravity position Gb related to the second moment Mb is almost unchanged. constant. That is, when the weight mainly composed of the weight of the counterweight 13 (the weight of the portion in the second direction D2 from the turning center C) is Wb, the second moment Mb is the weight Wb and the center of gravity position from the turning center C. It is represented by the product with the distance Lb to Gb (Mb=Wb×Lb).

On the other hand, since the distance L (for example, the distance L1 shown in FIG. 10, the distance L2 shown in FIG. 13, etc.) from the turning center C to the center-of-gravity position Gf of the hoisting member changes depending on the attitude of the hoisting member including the boom 14 and the jib 17, 1 moment Mf fluctuates according to the posture of the hoisting 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 hoisting member is Wat, the first moment Mf is represented by the product of the weight Wat and the distance L (for example, distance L1, distance L2, etc.) from the turning center C to the center of gravity position Gf (Mf = Wat x L).

For example, as shown in FIG. 13, when the boom 14 is erected to some extent with respect to the upper slewing structure 12 until the angle of inclination 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 about the turning center C may become substantially equal. In this substantially uniform state, the moment Mt becomes substantially zero. The weight of the crane 10 is generally evenly borne over the entire length of the crawler 7 in the front-rear direction.

Compared to the substantially uniform state, as shown in FIG. 10, for example, the boom 14 is laid down to some extent with respect to the upper rotating body 12 until the inclination angle of the boom 14 with respect to the ground becomes relatively small, and the boom When the relative angle of the jib 17 to 14 is relatively large (relative angle θ1), the center of gravity Gf of the hoisting member moves in the first direction D1, so the first moment Mf about 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 uniform state (Mt=Mf−Mb>0).

Here, when the center of the moment for calculating the moment is moved in the longitudinal direction from the turning center C, and the front-rear moment is calculated based on the center position after the movement, the front-rear moment is the same. is defined as the "moment equilibrium position". 10, 11 and 13, a portion S of the crawler frame 1 whose longitudinal position corresponds to the rotation axis CB of the drive tumbler 4a is referred to as a tipping fulcrum S. As shown in FIGS. The overturning fulcrum S is a position that becomes a fulcrum when it is assumed that the support member 80 is not provided on the crawler frame 1 and the crane 10 overturns.

In the substantially uniform state described above (for example, the state shown in FIG. 13), the moment balance position P1 substantially coincides with the position of the turning center C. As shown in FIG. 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. Even if the moment Mt becomes a positive value as shown in FIG. 10 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 overturn immediately. That is, the biased state is a state in which the crawler frame 1 of the lower traveling body 11 resists the crane 10 to fall in the first direction D1 due to the moment Mt.

In the biased state 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 balanced position P2 to the overturning fulcrum S. As shown in FIG. In such a biased state, not the entire crawler frame 1 but the tip of the crawler frame 1 (the portion from the balanced position P2 to the overturning fulcrum S) resists the moment Mt, and the bending rigidity of the tip of the crawler frame 1 is prevents the crane 10 from overturning and maintains its posture.

For example, as shown in FIG. 11, when the center of gravity position Gf of the hoisting member moves further in the first direction D1 than the position shown in FIG. almost coincides with In this state just before the fall, each of the tip portions of the pair of crawler frames 1 receives almost all of the moment Mt. A circular arrow Mr in FIG. 11 indicates a state where the tip of the crawler frame 1 resists the moment Mt.

10, the biased state shown in FIG. 13, the state just before overturning shown in FIG. 11, and the like.

Therefore, the crane 10 according to this embodiment includes a plurality of support members 80 as described above, and each support member 80 has its leg portion 82 displaced in the first direction D1 with respect to the rotation axis CB of the drive tumbler 4a. It is configured to be in the 10, the biased state shown in FIG. 13, and the state just before overturning shown in FIG. can be detected well. If the moment received by the tip of the crawler frame 1 can be obtained based on the detected strain, various possible states of the crane 10 can be determined. Therefore, in the present embodiment, it is possible to obtain an index as to what state the balance of the crane 10 in the longitudinal direction is.

In this embodiment, as described above, the strain generated in the beam 81 of the support member 80 detected by the strain detector 90 can be obtained without the operator performing complicated work. The detected strain is used for the crane 10 to safely stand up and lay down. Specifically, it is as follows.

In the assembling work of assembling the crane 10, as shown in FIG. 8, the boom 14 and the jib 17 are attached to the upper revolving structure 12 in a state of being laid down substantially parallel to the ground GR (falling state). When the lifting work is performed, 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 motion in which the inclination angle of the boom 14 with respect to the ground GR gradually increases.

When the hoisting member is displaced from the lying state to the standing state as described above, first, the inclination angle of the boom 14 is gradually increased while the roller 17R provided at the tip portion 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 is gradually reduced.

For example, when the relative angle reaches angle θ1 as shown in FIG. Since the roller 17R of 17B is separated from the ground GR, the crane 10 is acted upon by a moment Mf.

At this time, the notification control unit 102 of the controller 100 controls the notification device 110 so that information regarding the front-rear balance of the crane 10 based on the detection signal output by the strain detection unit 90 is sent to the operator via the notification device 110. be notified. Thereby, the operator can obtain information about the front-rear balance of the crane 10 through the notification device 110 . For example, when the operator recognizes that the crane 10 shown in FIG. 10 is in an unstable state, the operator reduces the tilt angle of the boom 14 again and adjusts the rollers of the tip 17B of the jib 17 as shown in FIG. 17R is grounded. Then, the operator gradually increases the inclination angle of the boom 14 while the roller 17R provided at the tip portion 17B of the jib 17 is in contact with the ground GR. In this operation, the angle of the jib 17 relative to the boom 14 gradually decreases (for example, the state shown in FIG. 12).

For example, when the relative angle reaches angle θ2 as shown in FIG. Since the roller 17R of 17B is separated from the ground GR, the crane 10 is acted upon by a moment Mf. Since the moment balance position P1 at this time is located near the turning center C, the hoisting member of the crane 10 can be safely erected.

It should be noted that the disassembly work for disassembling the crane 10 can be safely performed by performing the reverse operation of the assembly work described above.

[Moment calculation method]
A method of calculating the moment acting on the tip of the crawler frame 1 will be specifically described below.

As shown in FIG. 5 described above, in this embodiment, the beam 81 of the support member 80 has a closed cross-sectional structure. When the beam 81 receives a bending load in the vertical direction and bending deformation occurs in the beam 81 when the hoisting member performs the standing motion and the falling motion, the upper portion of the beam 81 above the neutral plane (neutral axis) is compressed. , and the area below the neutral plane is stretched and stretched.

The strain on the upper and lower portions of the beam 81 increases in proportion to the distance from the neutral plane. In the closed section structure as shown in FIG. 5, the upper plate portion 811 and the lower plate portion 812 of the beam 81 are positioned at a large distance from the neutral plane. stress) occurs. Therefore, as in the present embodiment, by providing the first strain gauge 90A and the second strain gauge 90B of the strain detection unit 90 on the upper plate portion 811 and the lower plate portion 812, the strain value corresponding to the moment is Large values can be detected. This makes it possible to improve the strain detection accuracy.

Here, the strain generated in the upper plate portion 811 is ε1, and the strain generated in the lower plate portion 812 is ε2. Also, the distance from the neutral plane of the beam 81 to the first strain gauge 90A is r1, and the distance from the neutral plane to the second strain gauge 90B is r2. In addition, let I be the geometrical moment of inertia of the cross section whose strain is to be measured, and let E be the modulus of longitudinal elasticity. Among the stresses generated only by the bending moment in the beam 81, let the upper stress be σmt and the lower stress be σmc.

It should be noted that the neutral plane (neutral axis) of the bending deformation of the beam 81 is not always positioned at the center of the beam 81 in the vertical direction. Therefore, the upper stress σmt and the lower stress σmc may differ. In such a case, the ratio of the upper stress σmt to the lower stress σmc (σmt:σmc) is the same as the distance from the neutral plane (r1:r2) (σmt:σmc=r1:r2). Also, the beam 81 may receive a compressive force σn (axial force) in its longitudinal direction. The calculation method of the moment considering the above premise is as follows.

FIG. 14 is a diagram schematically showing the stress distribution occurring in the cross section of the strain measurement target in the beam 81. As shown in FIG. As shown in FIG. 14, the stress distribution is obtained by the sum of the stress (σmt, σmc) due to the bending moment and the compressive force σn described above.

Therefore, the equation for obtaining the bending stress σmt required to obtain the moment M is the following equation (1).

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

The following formula (2) is obtained from the above formula (1).

σmt=E(ε1−ε2)/(1+r2/r1) (2)

Therefore, the moment M loaded on the beam 81 is given by the following equation (3).

M=E×σmt×I/r1 (3)

Since the crane 10 has a pair of crawler frames 1 and each crawler frame 1 is provided with a pair of support members 80, the overturning moment Mt is applied to the pair of support members 80 provided on the right crawler frame 1. Let MR be the moment obtained from the strain of the beam 81, and let ML be the moment obtained from the strain of the beam 81 of the pair of support members 80 provided on the left crawler frame 1, the following equation (4) is obtained.

Mt=MR+ML (4)

The moment MR is the sum of the moment MR1 obtained from the strain of the beam 81 of one support member 80 provided on the right crawler frame 1 and the moment MR2 obtained from the strain of the beam 81 of the other support member 80. (MR=MR1+MR2). Similarly, the moment ML is the moment ML1 obtained from the strain of the beam 81 of one support member 80 provided on the left crawler frame 1 and the moment ML2 obtained from the strain of the beam 81 of the other support member 80. is the sum (ML=ML1+ML2).

The moment Mt calculated as described above is calculated by the calculation section 101 of the controller 100 described above based on the detection signal input from the strain detection section 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 preset time intervals, or continuously (always).

Note that when the compressive force σn (axial force) described above does not have to be considered, the moment M is expressed by the following equation (5).

M=E×I(|ε1/r1|+|ε2/r2|)/2 (5)

[Modification]
Next, a modified example of the above embodiment will be described. This modification differs from the above embodiment in that the beam 81 of the support member 80 is composed of a plurality of members that can be attached and detached from each other. The configuration of the crane 10 according to the modified example is the same as that of the above-described embodiment except for the difference.

FIG. 15 is a plan view showing the lower traveling body 11 of the crane 10 according to Modification 1 of the embodiment and the support member 80 provided in the crawler traveling device 3 of the lower traveling body 11 . 16 and 17 are perspective views showing the crawler frame 1 and the support member 80 attached to the crawler frame 1 in the crane 10 according to Modification 1 of the embodiment. 18 and 19 are side views showing the crawler frame 1 and the support member 80 shown in FIG. 16. FIG. 16 and 18 are diagrams showing a state in which part of the beam 81 of the support member 80 is removed from the mounting portion, and FIGS. It is a figure which shows the state attached to the attachment part.

As shown in FIG. 16, in the crane 10 according to Modification 1, the beam 81 of the support member 80 includes a first member 81A including the base end portion 8A of the beam 81 and a second member including the tip portion 8B of the beam 81. 81B. The first member 81A and the second member 81B can be attached to and detached from each other. Further, in Modification 1, the second member 81B removed from the first member 81A can be used as a member constituting the trans lifter 70 provided on the front axle 2b and the rear axle 2c of the lower traveling body 11. can.

As shown in FIG. 16, the first member 81A is attached to the frame main body 1A of the crawler frame 1. As shown in FIG. The first member 81A has an upper plate portion 811A, a lower plate portion 812A arranged with a gap below the upper plate portion 811A, and a pair of side plate portions 813A and 814A. One side plate portion 813A connects the right end portions of the upper plate portion 811A and the lower plate portion 812A, and the other side plate portion 814A connects the right end portions of the upper plate portion 811A and the lower plate portion 812A. there is

As shown in FIGS. 16 and 18, the base end portion 8A of the first member 81A is provided with a connected portion for attaching the first member 81A to the crawler frame 1. As shown in FIGS. The connected portion includes a through hole provided in the base end portion of the upper plate portion 811A and a through hole provided in the base end portion of the lower plate portion 812A. On the other hand, the frame main body 1A of the crawler frame 1 is provided with connecting portions. The connection portion is configured by a through hole provided in the upper plate portion 111 of the frame body 1A and a through hole provided in the lower plate portion 112 . A vertically extending pin 86A is inserted through the through-hole forming the connected portion and the through-hole forming the connecting portion in a state of being aligned with each other. Thereby, the first member 81A is attached to the crawler frame 1 so as to be rotatable around the pin 86A.

A strain detector 90 is provided in the first member 81A. Specifically, the first member 81A has, for example, a closed cross-sectional structure as shown in FIG. 5, as in the above embodiment. A first strain gauge 90A is provided on the upper plate portion 811A of the first member 81A forming the closed cross section, and a second strain gauge is provided on the lower plate portion 812A of the first member 81A forming the closed cross section. A gauge 90B is provided. Note that the strain detector 90 may be provided on the second member 81B.

A pair of side plate portions 813A and 814A of the first member 81A have attachment portions on the opposite side of the connected portions. The attachment portion is a portion for attaching the second member 81B to the first member 81A. The mounting portion is composed of a pair of hook portions 88A and a pair of lower through holes 89A provided below the hook portions 88A.

The second member 81B has an upper plate portion 811B, a lower plate portion 812B arranged with a gap below the upper plate portion 811B, and a pair of side plate portions 813B and 814B. One side plate portion 813B connects the right end portions of the upper plate portion 811B and the lower plate portion 812B, and the other side plate portion 814B connects the right end portions of the upper plate portion 811B and the lower plate portion 812B. there is The second member 81B has, for example, a closed cross-sectional structure as shown in FIG. 5, as in the above embodiment.

The upper plate portion 811A of the first member 81A and the upper plate portion 811B of the second member 81B constitute the upper plate portion 811 of the beam 81, the lower plate portion 812A of the first member 81A and the lower plate portion of the second member 81B. 812B constitutes the lower plate portion 812 of the beam 81 . One side plate portion 813A of the first member 81A and one side plate portion 813B of the second member 81B constitute one side plate portion 813 of the beam 81, and the other side plate portion 814A of the first member 81A and the second member 81B The other side plate portion 814 B of the beam 81 constitutes the other side plate portion 814 of the beam 81 .

A tip portion of the second member 81B supports the leg portion 82 . The leg portion 82 is connected to the distal end portion of the second member 81B by a connecting member 87A.

The pair of side plate portions 813B and 814B of the second member 81B have attached portions on the side opposite to the tip portion of the second member 81B. The attached portion is configured to be engageable with the attaching portion of the first member 81A. The mounting portion includes a pair of upper through-holes 88B, a pair of lower through-holes 89B provided below the upper through-holes 88B, and a pair of pins inserted through these through-holes. A pin is previously inserted and fixed in the upper through hole 88B.

As shown in FIGS. 16 and 17, the pin arranged in the upper through-hole 88B of the second member 81B is engaged with the hook portion 88A of the first member 81A, and the lower through-hole 89B of the second member 81B is engaged. The second member 81B can be attached to the first member 81A by inserting pins into these through holes in a state where the positions are aligned with the positions of the lower through holes 89A in the first member 81A. When the second member 81B is removed from the first member 81A, the work described above is performed in reverse order.

When the second member 81B is removed from the first member 81A, the first member 81A rotates around the pin 86A and rotates around the pin 86A, as shown by the dashed line in FIG. Housed in the housing space.

The second member 81B removed from the first member 81A can be used as a member constituting the trans lifter 70 provided on the front axle 2b and the rear axle 2c of the lower traveling body 11. As shown in FIG. Specifically, the front axle 2b is provided with a pair of base end members 70A having the same structure as the first member 81A of the support member 80 so as to be rotatable with respect to the front axle 2b. 2c, a pair of base end members 70A having the same structure as the first member 81A of the support member 80 are provided rotatably with respect to the rear axle 2c. The second member 81B removed from the first member 81A can constitute a part of the trans lifter 70 by being attached to the base end member 70A of the trans lifter 80. As shown in FIG.

In the specific example shown in FIGS. 17 and 19, when the second member 81B is attached to the first member 81A, the upper plate portion 811A of the first member 81A and the upper plate portion 811B of the second member 81B are positioned horizontally. aligned in a direction and in contact with each other. Therefore, when a moment is generated in a direction that causes the crane 10 to fall in the first direction D1, and the leg of the support member 80 receives an upward reaction force from the ground due to the moment, the first member 81A and strain can be effectively generated in the second member 81B.

FIG. 20 is a perspective view schematically showing Modification 2 of the embodiment. In Modified Example 2 shown in FIG. 20, the beam 81 further has a measurement support 200 (deformable member) for attaching a strain gauge (strain detector). The measurement abutment 200 is located at a position where the strain occurring in the beam 81 can be detected in a state where the distal end portion 14B of the boom 14 is deviated from the base end portion 14A of the boom 14 in the first direction D1 in the front-rear direction. are placed in As long as the measurement abutment 200 is arranged at such a position, the site where the measurement abutment 200 is arranged is not particularly limited.

20, the beam 81 has a reinforcing plate 816 extending in a direction orthogonal to the longitudinal direction of the beam 81 and having a surface facing the longitudinal direction (forward). In Modified Example 2 shown in FIG. 20 , measurement support 200 is provided so as to straddle reinforcing plate 816 and upper plate portion 811 of beam 81 . In other words, the measurement support 200 is arranged at the corner formed by the reinforcing plate 816 and the upper plate portion 811 .

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 arranged to face the reinforcing plate 816 and connected to the reinforcing plate 816 . The second surface 200B is a surface arranged to face the upper plate portion 811 and connected to the upper plate portion 811 . 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 holds the strain gauge 90A. In the specific example shown in FIG. 20, the holding surface 200C has an inclined surface that slopes upward toward the front and holds the strain gauge 90A. In the specific example shown in FIG. 20, the inclined surface is an arc-shaped curved surface (concave curved surface), but may be a flat surface or a convex curved surface. Further, in the specific example shown in FIG. 20, the measurement support 200 has a substantially L-shape, but the shape of the measurement support 200 is not limited to a substantially L-shape.

Moreover, the measurement support 200 is arranged not only at the corner formed by the reinforcing plate 816 and the upper plate portion 811 as described above, but also at the corner formed by the reinforcing plate 816 and the lower plate portion 812 . is also located in Then, the bending moment is applied to the beam 81 and the beam 81 is subjected to bending deformation by the erecting motion and the falling down motion of the hoisting member. As a result, the holding surface 200C of the upper measurement abutment 200 is pulled and strains in the extending direction. Also, the holding surface of the lower measurement abutment is compressed and distorted in the shrinking direction. 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 strain can be adjusted by changing the radius of curvature of the arc.

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

For example, in the above-described embodiment, as shown in FIG. 3, the first direction D1 is the direction from the center of the crawler frame 1 to the tumbler bracket 1B in the longitudinal direction, and the first direction D1 is the direction from the center of the crawler frame 1 to the idler 4c. The second direction D2 is defined as the second direction D2, but it is not limited to this. The direction may be toward the bracket 1B.

In the above embodiment, the strain detectors 90 are provided in each of the plurality of support members 80, but the present invention is not limited to this, and the strain detectors 90 may be provided only in some of the plurality of support members 80. .

In the above embodiment, the strain detector 90 is composed of a plurality of strain gauges, but may be composed of a single strain gauge.

In the above-described embodiment, the leg portion 82 is configured by a hydraulic cylinder including a cylinder body 83 and a rod 84 that can slide vertically with respect to the cylinder body 83. Other members may be used as long as they are capable of receiving the reaction force and causing the beam 81 to distort.

In the above-described embodiment, at least part of the beam 81 is detachably attached to the mounting portion to which the at least part is attached. may be fixed to

Although in the above embodiment the luffing member included a jib 17, the invention is also applicable to cranes that do not have a jib.

In the above-described embodiment, the beam 81 of the support member 80 has a structure in which the cross section perpendicular to the longitudinal direction is closed as shown in FIG. It may have a structure whose cross section is an I cross section.

In addition, the crane 10 according to the above-described embodiment includes a strain detector 90 capable of detecting information necessary for safely raising and lowering the hoisting member during the assembly work and disassembly work of the crane 10. Also, the information detected by the strain detector 90 can be used to safely raise and lower the hoisting member in the lifting work, which is work other than assembly work and disassembly work. Specifically, the strain detector 90 detects strain occurring in the beam 81 of the support member 80 . The detected strain of the beam 81 determines the state of the crane 10, such as a stable state in which the front and rear of the crane 10 are balanced, an unstable state in which the crane 10 is approaching tipping over in the first direction D1, and the like. It becomes an index for (guessing). Therefore, in the lifting work, the strain detected by the strain detecting section 90 is used as an index for raising and lowering the hoisting member, thereby improving the safety of the hoisting work.

1 crawler frame 1A frame main body 3 crawler travel device 4a drive tumbler (first wheel)
4c idler (second wheel)
7 Crawler 10 Mobile Crane 11 Undercarriage 12 Upper Revolving Body 14 Boom 17 Jib 70 Translifter 80 Support Member 81 Beam of Support Member 8A Base End of Beam 8B Tip of Beam 81A First Member 81B Second Member 82 Leg Part 83 Cylinder body 84 Rod 85 Lower end of leg 90 Strain detector 90A First strain gauge 90B Second strain gauge 100 Controller 101 Calculation unit 102 Notification control unit 110 Notification device CB Rotating shaft of drive tumbler (first wheel axis of rotation)
D1 First direction among front and rear directions GR Ground

Claims (7)

a lower traveling body having a first crawler traveling device and a second crawler traveling device spaced apart in the left-right direction;
an upper rotating body rotatably supported on the lower traveling body;
a hoisting member including a boom hoistably supported by the upper slewing structure;
A right support member and a left support member provided in the first crawler traveling device;
A right support member and a left support member provided in the second crawler traveling device;
At least one strain detector provided on at least one support member among the four support members,
Each crawler traveling device is rotatably supported by a crawler frame extending in the front-rear direction, and an end located in a first direction, which is one direction in the front-rear direction, of both ends of the crawler frame in the front-rear direction. a first wheel and a second wheel rotatably supported at an end located in a second direction opposite to the first direction among the both ends; and the first wheel and the second wheel a crawler that is endlessly supported and capable of revolving,
Each support member includes a beam having a base end portion supported by the crawler frame and a tip end portion located in a first direction relative to the base end portion in the front-rear direction, and supported by the tip end portion of the beam. and a leg configured to extend downward from the tip and have a lower end in contact with the ground,
The leg portion of the right support member is deviated in the first direction from the rotation axis of the first wheel and positioned to the right of the crawler frame, and the leg portion of the left support member the part is located at a position shifted in the first direction with respect to the rotation axis of the first wheel and is located to the left of the crawler frame,
The mobile crane, wherein the at least one strain detector is configured to detect strain occurring in the beam in the at least one support member. 2. The leg portion according to claim 1, wherein the leg includes a cylinder body supported by the tip of the beam and extending downward from the tip, and a rod vertically slidable with respect to the cylinder body. mobile crane. The mobile crane according to claim 1 or 2, wherein the strain detector includes a first device that detects strain occurring in the upper portion of the beam, and a second device that detects strain occurring in the lower portion of the beam. . 4. A notification device according to any one of claims 1 to 3, further comprising a notification device for notifying an operator of information regarding the front-rear balance of the mobile crane based on the detection signal output by the strain detection unit. The mobile crane described in . 5. The mobile crane according to any one of claims 1 to 4, further comprising a calculation unit that calculates a moment in a direction in which the mobile crane tends to fall in the first direction based on the detection signal output by the strain detection unit. The mobile crane described in . The mobile crane according to any one of claims 1 to 5, wherein at least part of said beam is detachable from a mounting part to which said at least part is mounted. The at least one strain detection unit is configured to be capable of detecting strain generated in the beam in either one of the right support member and the left support member provided in the first crawler traveling device. is a first strain detector,
The mobile crane is configured to be able to detect the strain generated in the beam in either one of the right support member and the left support member provided in the second crawler traveling device. The mobile crane according to any one of claims 1 to 6, further comprising a strain detector.

Images