CN109689562B

CN109689562B - Crane with a movable crane

Info

Publication number: CN109689562B
Application number: CN201780054589.5A
Authority: CN
Inventors: 原内裕司; 三好正人; 日樫谦司
Original assignee: Tadano Ltd
Current assignee: Tadano Ltd
Priority date: 2016-09-13
Filing date: 2017-09-13
Publication date: 2020-02-14
Anticipated expiration: 2037-09-13
Also published as: JPWO2018052050A1; JP6388095B2; CN109689562A; WO2018052050A1

Abstract

The crane disclosed by the invention comprises: a boom which is provided to be capable of lifting and retracting; a main hook that is suspended from a tip end portion of a boom and is capable of assuming a normal position in which a distance from the tip end portion is equal to or greater than a first threshold value and an overwind position in which the distance is smaller than the first threshold value; a boom having a pair of leg portions at a base end portion thereof and rotatably supported at a front end portion of the boom; and a control unit that determines whether the crane is in a predetermined state based on information on a lift angle of the boom and an elongation of the boom, and allows the main hook to move to the overwind position when the crane is determined to be in the predetermined state. This can improve the working efficiency in the boom extending/retracting work.

Description

Crane with a movable crane

Technical Field

The present invention relates to a crane, for example. More specifically, the present invention relates to a crane including a boom that can be extended or retracted.

Background

Patent document 1 discloses a mechanism including: a guide member mounted below the side surface of the front end portion of the base end arm; a guide roller mounted at the approximate center of the suspension arm; a boom side pin boss installed below a side surface of a central portion of the base end arm; and a boom side fixing pin installed at a front end portion of the boom.

When the boom extension work is performed, first, the boom base end portion is connected to the boom tip end portion. Subsequently, the boom is raised. Subsequently, when the boom is slightly extended, the boom side fixing pin is disengaged from the boom side pin boss. When the boom is further extended, the guide roller rolls along the slope of the guide, and the boom slowly moves away from the bottom surface of the base arm. When the guide roller is completely disengaged from the guide, the boom is suspended from the boom tip. Finally, the boom is extended by applying tension to the drawbar.

The boom storage work is performed in reverse steps to the boom extension work. When the boom is retracted with the boom hanging down from the boom tip end, the guide roller rolls along the guide. In this way, the boom arm is pulled against the bottom surface of the base end arm. When the boom is further contracted, the boom-side fixing pin is inserted into the boom-side pin holder. Thereby, the boom is fixed to the boom.

In the boom extending/retracting operation, the main hook has to be overwound in order to allow the main hook hanging down from the boom tip to pass through the branch-shaped boom base end. Therefore, the overwinding prevention function is released in the boom extending/retracting operation. However, in addition to the above, the main hook can be set to the overwound state, and therefore, the main hook may be brought into contact with the tip end portion of the boom and damaged by an erroneous operation. Further, there is also a case where a normal suspension load operation is performed in a state where the overwind prevention function is forgotten to be reset.

Patent document 2 discloses a technique of: the overwinding prevention function is basically maintained in a state in which the overwinding prevention function is set even during the boom extending/retracting operation, and the overwinding prevention function is released only during the period in which the release switch is pressed. According to such a configuration, since the overwind prevention function can be released only when necessary, damage due to overwinding can be prevented when unnecessary. In addition, the operator does not forget to reset the overwind prevention function.

However, the operator needs to perform the operation of raising and lowering or extending and retracting the boom while pressing the release switch, and the operability is poor. When the main hook is passed through the boom base end portion, the boom is completely raised, and therefore, the operator needs to operate the boom while viewing the boom substantially directly above the boom. Since the operator performs a troublesome operation in an uncomfortable posture, the burden on the operator is large, and the work efficiency may be reduced.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2000-44173

Patent document 2: japanese patent laid-open No. Hei 7-25588

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a crane capable of improving work efficiency in boom extension/retraction work.

Means for solving the problems

In one aspect of the crane according to the present invention, the crane includes: a boom which is provided to be capable of lifting and retracting; a main hook that is suspended from a front end portion of the boom and is capable of assuming a normal position in which a distance from the front end portion is greater than a first threshold value and an overwind position in which the distance is equal to or less than the first threshold value; a boom having a pair of leg portions at a base end portion thereof and rotatably supported at a tip end portion of the boom, wherein the main hook located at the overwind position is capable of passing between the pair of leg portions; a control unit having an overwind prevention function for preventing overwinding of the main hook, and switching between a set state and a release state of the overwind prevention function according to information on a lift angle of the boom and an extension amount of the boom; and a guide device that has a first guide portion provided to the boom and a second guide portion provided to the boom, and guides the boom to move in accordance with expansion and contraction of the boom by engagement between the first guide portion and the second guide portion, wherein the control unit performs any one of the following controls (1) to (4) when a position at which the boom is expanded from a contracted state and engagement between the first guide portion and the second guide portion is released is a first position, and a predetermined position on an expansion side of the boom from the first position is a second position: (1) in a state in which the overwind prevention function is set, when it is determined that the boom is in a lowered state based on the information and the first guide portion and the second guide portion of the guide device are in a guide state in which the boom is engaged with each other, the overwind prevention function is released; (2) in a case where it is determined that the boom is in a lowered state based on the information in the setting state of the overwind prevention function, and the boom is extended by an amount equal to or more than the amount of extension up to the first position and equal to or less than the amount of extension up to the second position, a function other than prohibiting extension of the boom among the overwind prevention functions is canceled; (3) in a state in which the overwind prevention function is set, when it is determined that the boom is in a raised state, the first guide portion and the second guide portion of the guide device are in a guide state in which they are engaged with each other, and the boom is in a lowered state based on the information, the overwind prevention function is released; (4) in the setting state of the overwind prevention function, when it is determined that the boom is in the upward state, the boom is not less than the extension to the first position and not more than the extension to the second position, and the boom is in the downward state based on the information, the function other than the prohibition of the boom extension in the overwind prevention function is canceled.

Effects of the invention

According to the present invention, it is possible to provide a crane capable of improving the working efficiency in the boom extending/retracting work.

Drawings

Fig. 1 is a side view of a mobile crane in a state where a boom is stored.

Fig. 2 is a left side view of the boom and the boom in a state where the boom is placed at the down position.

Fig. 3 is a right side view of the boom and the boom in a state where the boom is placed at the down position.

Fig. 4 is a side view of the guide member.

Fig. 5 is a perspective view of the first boom support member.

Fig. 6 is a perspective view of the second boom support member.

Fig. 7 is a block diagram of a control system.

Fig. 8 is a side view of the boom and the boom showing each stage of the boom extending/retracting operation.

Fig. 9 is a side view of the boom hanging down from the boom tip.

Fig. 10 is a side view of a state in which the boom is extended.

Detailed Description

Next, embodiments of the present invention will be described with reference to the drawings.

(Mobile crane)

First, an outline of a mobile crane C according to an embodiment of the present invention will be described. The mobile crane C includes: a boom 14 that is provided so as to be able to be raised and lowered and is extendable and retractable; a main hook 15m that is suspended from the tip end portion of the boom 14 and is capable of assuming a normal position in which the distance from the tip end portion is greater than a first threshold value and an overwind position in which the distance is equal to or less than the first threshold value; a boom 16 having a pair of leg portions 16c at a base end portion thereof and rotatably supported at a tip end portion of the boom 14; and a control unit 62 that determines whether or not the mobile crane C is in a predetermined state based on information on the lift angle of the boom 14 and the extension amount of the boom 14, and allows the main hook 15m to move to the overwind position when the determination is made that the mobile crane C is in the predetermined state; in the unwinding operation of the boom 16, when the boom 16 is rotated, the main hook 15m located at the overwind position passes through between the pair of leg portions 16c of the boom 16.

Next, a basic structure of the mobile crane C will be described. The traveling vehicle body 11 shown in fig. 1 includes wheels for traveling. A turntable 12 is mounted on the traveling vehicle body 11. The rotary table 12 can rotate 360 ° in the horizontal plane by the rotating motor. The rotating table 12 is provided with a cab 13.

The boom 14 is attached to the rotating table 12 so as to be movable up and down. The base end portion of the boom 14 is pivotally supported by the rotating table 12 via a pin. A lift cylinder is installed between the boom 14 and the rotating table 12. When the lift cylinder is extended, the boom 14 is raised. On the other hand, when the lift cylinder is contracted, the boom 14 is lowered.

The boom 14 is a multi-stage boom configured in a telescopic manner, and is composed of a base end arm 14a, an intermediate arm, and a tip end arm 14 b. The boom 14 is extended and contracted by a telescopic cylinder. The number of stages of the boom 14 is not particularly limited. The boom 14 may be a two-stage type without an intermediate arm, or may be a four-stage or more type structure including a plurality of intermediate arms.

A main wire rope having a main hook 15m is suspended from a distal end portion 14c of the boom 14 (distal end arm 14 b). The main wire rope is guided to the rotary table 12 along the boom 14 and wound around the main winding winch. The main winding winch is driven by the main winding hoisting motor to rotate forward and reversely. The main wire rope is wound or unwound according to the rotation direction of the main winch, and the main hook 15m is raised or lowered.

An auxiliary wire rope including an auxiliary hook 15a is suspended from a sheave (also referred to as an arm top sheave) provided at the boom tip portion 14 c. The auxiliary wire rope is guided to the rotary table 12 along the boom 14 and wound around an auxiliary winding winch. The auxiliary winding winch is driven by the auxiliary winding hoisting motor to rotate forward and reversely. The auxiliary hook 15a is raised or lowered by winding or unwinding the auxiliary wire rope in accordance with the rotation direction of the auxiliary winding winch.

By combining the rotation of the rotating table 12, the lifting and contraction of the boom 14, and the lifting and lowering of the

hooks

15m and 15a, the cargo can be loaded and unloaded in the three-dimensional space.

(boom)

The mobile crane C includes a boom 16. The boom 16 is an overall elongated rod-like member. The boom 16 has a pair of legs 16c at least at the base end portion. The pair of leg portions 16c are separated from each other in the width direction of the boom 16 (the vertical direction in fig. 1, and the front-back direction in fig. 2 and 3). That is, the base end portion 16a of the boom 16 has a bifurcated shape.

The boom 16 is used when a lift or working radius larger than that of the boom length when the boom 14 is fully extended is obtained. The boom 16 can be extended or retracted relative to the boom 14. When not in use, the boom 16 is stored along the side surface of the boom 14 (see fig. 1). In use, the boom 16 is extended forward of the boom 14 with the boom base end portion 16a connected to the boom tip end portion 14c (see fig. 10).

The front end 16b of the boom 16 is provided with a pulley. In the extended state of the boom 16, the auxiliary hook 15a hangs down from the front end 16b of the boom.

A tilt cylinder 17 is mounted on the boom 16. A rod 18 is connected to the piston of the tilt cylinder 17. Further, a tie rod connecting rod 19 is provided at the boom tip portion 14 c. In the extended state of the boom 16, the tie bar 18 is connected to the tie bar link 19 (see fig. 10).

In the extended state of the boom 16, the tilt cylinder 17 is extended and contracted to change the tilt angle of the boom 16. When the tilt angle of the boom 16 is changed, the boom 16 is raised and lowered with respect to the boom 14. In the present embodiment, when the tilt cylinder 17 is contracted, the boom 16 is lowered. On the other hand, when the tilt cylinder 17 extends, the boom 16 rises. Instead, the following configuration may be adopted: when the tilt cylinder 17 is contracted, the boom 16 is raised, and when the tilt cylinder 17 is extended, the boom 16 is lowered.

Fig. 2 and 3 are left and right side views of a state in which the boom 16 is disposed at a lower position along the bottom surface of the base end arm 14a (the lower side surface of the boom 14 in a lowered state). As will be described later, in the boom extending/retracting operation, the boom tip end portion 14c and the boom base end portion 16a are connected or disconnected with the boom 16 being disposed at the lower-lying position.

Boom connecting shafts 21 horizontally projecting are provided on both sides of the boom tip portion 14 c. Further, a boom base end engaging portion 22 is provided at each end of the bifurcated boom base end portion 16a (specifically, the pair of leg portions 16 c).

The boom base end engaging portions 22 are each formed in a U shape and into which the boom connecting shaft 21 can be fitted. Further, an insertion hole is formed at the tip end of the boom base end engaging portion 22. The boom connecting shaft 21 is fitted into the boom base end engaging portion 22, and the pin 23 is inserted into the insertion hole, thereby preventing the boom connecting shaft 21 from coming off. Thereby, the boom base end engaging portion 22 is connected to the boom connecting shaft 21.

(guide member)

As shown in fig. 3, a guide member 30 (also referred to as a guide device) is provided on the right side of the boom 14. The guide member 30 is a member for guiding the boom 16 to move while maintaining its posture in accordance with the extension and contraction of the boom 14 during the boom extension/retraction work. As shown in fig. 4, the guide member 30 is composed of a guide roller 31 (also referred to as a second guide portion) and a guide 32 (also referred to as a first guide portion) that guides the guide roller 31.

The guide roller 31 is provided to the boom 16. Specifically, an arm 33 protruding toward the bottom surface side is provided on the base end side surface of the boom 16. The guide roller 31 is rotatably provided at the distal end of the arm 33. In fig. 4, the bottom surface (upper surface in fig. 4) of the boom 16 faces the bottom surface of the base arm 14 a.

The guide 32 is provided to the boom 14. Specifically, the guide 32 is provided on the side surface of the distal end of the base-end arm 14a so as to protrude toward the bottom surface side. The guide 32 has a first rail member 34 and a second rail member 35. The two-dot chain line in fig. 4 indicates the side wall 36 (also referred to as a horizontal direction regulating portion) constituting the guide 32. The side wall 36 supports the first rail member 34 and the second rail member 35, and regulates the movement of the guide roller 31 in the lateral direction (the horizontal direction and the direction perpendicular to the paper surface). For convenience of explanation, only the outer shape of the side wall 36 is shown by a two-dot chain line.

The surface of the first rail member 34 is a first rail surface 34 s. On the other hand, the surface of the second rail member 35 is a second rail surface 35 s. The guide roller 31 rolls on the first rail surface 34s and the second rail surface 35s, thereby guiding the boom 16 to move in accordance with the expansion and contraction of the boom 14.

The first rail surface 34s is inclined in a direction from the tip end of the boom 14 toward the base end (in other words, toward the left side in fig. 4) toward the bottom surface of the boom 14 (in other words, toward the upper side in fig. 4). Therefore, as described later, when the guide roller 31 rolls on the first rail surface 34s as the boom 14 extends during the boom extension work, the boom 16 is pulled away from the bottom surface of the base arm 14 a. In the boom storing operation, when the guide roller 31 rolls on the first rail surface 34s as the boom 14 contracts, the boom 16 is pulled against the bottom surface of the base end arm 14 a.

The second rail surface 35s is parallel to the central axis of the boom 14. The distal end portion of the second track surface 35s is connected to the proximal end portion of the first track surface 34 s. Therefore, as described later, when the guide roller 31 rolls on the second rail surface 35s in accordance with the expansion and contraction of the boom 14 during the boom extension/retraction work, the boom 16 moves along the base end arm 14a while being pulled toward the bottom surface of the base end arm 14 a.

In the present embodiment, the guide roller 31 is provided on the boom 16, and the guide 32 is provided on the base end arm 14 a. Instead of this, the guide roller 31 may be provided on the base end arm 14a, and the guide 32 may be provided on the boom 16. In this case, the guide roller provided to the base end arm 14a is a first guide portion. On the other hand, the guide 32 provided to the boom 16 is a second guide portion.

(boom support Member)

As shown in fig. 2, the boom 14 has a first boom support member 40 and a second boom support member 50. Specifically, the first boom support member 40 and the second boom support member 50 are provided at an intermediate portion in the axial direction of the boom 14 so as to be separated in the axial direction of the boom 14. In the case of the present embodiment, the first arm support member 40 is provided closer to the distal end side of the boom 14 than the second arm support member 50.

The first boom support member 40 supports the boom 16 in the stored state. The first boom support member 40 pivots the boom 16 between a storage position along the side surface of the boom 14 and a lower holding position. The first boom support member 50 supports the boom 16 in the stored state.

The first boom support member 40 is explained with reference to fig. 5. A bracket 41 is pivotally supported on a substantially central bottom side of the base end arm 14 a. A hydraulic cylinder 42 is mounted between the upper side surface of the base end arm 14a and the bracket 41. The bracket 41 is rotated with respect to the base-end arm 14a by extending and contracting the hydraulic cylinder 42.

The bracket 41 is provided with a boom fixing pin 43. The tip end of the boom fixing pin 43 is conical, and the other portions are cylindrical. The boom fixing pin 43 is disposed parallel to the central axis of the boom 14, and has a tip end portion facing the tip end of the boom 14. The boom fixing pin 43 may be disposed parallel to the central axis of the boom 16.

A pin boss 44 is provided on the substantially central bottom surface of the boom 16. In fig. 5, the bottom surface of the boom 16 faces the base end arm 14 a. The pin boss 44 has a front end rib 45 and a rear end rib 46. The front end rib 45 is formed with a front end insertion hole 47. The rear end rib 46 is formed with a rear end insertion hole 48. The boom fixing pin 43 can be inserted into or pulled out from the front end insertion hole 47 and the rear end insertion hole 48.

The front end insertion hole 47 and the rear end insertion hole 48 are arranged such that: the boom 16 has a center axis parallel to the center axis of the boom 14 in a state pulled against the bottom surface of the base end arm 14 a. The front end insertion hole 47 and the rear end insertion hole 48 may be arranged such that their central axes are parallel to the central axis of the boom 16.

In the present embodiment, the boom fixing pin 43 is provided on the base end arm 14a, and the pin boss 44 is provided on the boom 16. Instead of this, the boom fixing pin 43 may be provided on the boom 16 and the pin boss 44 may be provided on the base end arm 14 a.

The second boom support member 50 is explained with reference to fig. 6. An arm 51 is provided on the bottom surface (specifically, one end in the width direction of the bottom surface) of the base end portion of the base end arm 14 a. The front end of the arm 51 is provided with a sub-pin 52. The sub pin 52 has a smaller diameter and a shorter length than the boom fixing pin 43, and the tip of the sub pin 52 is conical and the other part is cylindrical. The sub-pin 52 is disposed parallel to the central axis of the boom 14, and has a tip end portion facing the tip end of the boom 14.

A sub-boss 53 is provided on the bottom surface of the front end of the boom 16. In fig. 6, the bottom surface of the boom 16 faces the base end arm 14 a. The secondary pin boss 53 has a rib 54. The rib 54 has an insertion hole 55 into which the sub-pin 52 can be inserted.

(overwinding prevention device)

The traveling crane C includes an overwind prevention device 60 for preventing the main hook 15m and the auxiliary hook 15a from being excessively wound. The overwind prevention device 60 includes an auxiliary overwind detection sensor 61a and a main overwind detection sensor 61m shown in fig. 1.

The main overwind detection sensor 61m is a sensor for detecting overwind of the main hook 15 m. The overwind state of the main hook 15m means: the distance between the lower portion of the boom tip portion 14c and the upper portion of the main hook 15m is equal to or less than a predetermined length (also referred to as a first threshold value). The position of the main hook 15m in the overwind state is referred to as an overwind position of the main hook 15 m.

On the other hand, a state in which the distance between the lower portion of the boom tip portion 14c and the upper portion of the main hook 15m is longer than a predetermined length is referred to as a normal state of the main hook 15 m. The position of the main hook 15m in the normal state is referred to as a normal position of the main hook 15 m.

The configuration of the main overwind detection sensor 61m is not particularly limited as long as it can detect overwinding of the main hook 15 m. An example of the main overwinding detection sensor 61m is an overwinding detection sensor including a switch for detecting overwinding provided at the boom tip portion 14c and a hammer suspended from an operating arm of the switch.

When the main hook 15m is wound up and the distance from the lower portion of the boom tip portion 14c is equal to or less than a predetermined length, the hammer is lifted by the main hook 15m and the working arm is rotated. Thereby, the on/off of the switch for detecting overwinding is switched, and the overwinding state of the main hook 15m is detected.

The auxiliary overwind detection sensor 61a is a sensor for detecting overwind of the auxiliary hook 15 a. As described later, in the extended state of the boom 16, the auxiliary overwinding detection sensor 61a is attached to the boom tip portion 16b together with the auxiliary hook 15 a.

The overwind state of the auxiliary hook 15a means: the distance between the lower portion of the boom tip portion 14c or the lower portion of the boom tip portion 16b and the upper portion of the auxiliary hook 15a is equal to or less than a predetermined length (also referred to as a second threshold value). The position of the auxiliary hook 15a in the overwind state is referred to as an overwind position of the auxiliary hook 15 a.

A state in which the distance between the lower portion of the boom tip portion 14c or the lower portion of the boom tip portion 16b and the upper portion of the auxiliary hook 15a is longer than a predetermined length is referred to as a normal state of the auxiliary hook 15 a. The position of the auxiliary hook 15a in the normal state is referred to as the normal position of the auxiliary hook 15 a. The configuration of the auxiliary overwind detection sensor 61a is not particularly limited as long as it can detect overwinding of the auxiliary hook 15a, and may be the same configuration as the main overwind detection sensor 61 m.

As shown in fig. 7, the overwinding prevention device 60 includes a control unit 62. The control unit 62 may be a vehicle-mounted computer including an input terminal, an output terminal, a CPU, a memory, and the like, or may be a circuit including a relay, a comparator, and the like.

The control unit 62 has an overwind prevention function of stopping the winding operation of the

hooks

15m and 15a when one or both of the auxiliary overwind detection sensor 61a and the main overwind detection sensor 61m detect an overwind state.

Here, the operation of turning up the

hooks

15m and 15a is the operation of the mobile crane C, and is an operation of shortening the distance between the main hook 15m and the boom tip portion 14C and the distance between the auxiliary hook 15a and the boom tip portion 14C or the boom tip portion 16 b. Specifically, the operation of winding up the

hooks

15m and 15a refers to the winding up of the main winding winch, the winding up of the auxiliary winding winch, the extension of the boom 14, and the lowering of the boom 14.

The control unit 62 has a function of stopping the operation of the movable unit 63 of the mobile crane C such as the boom 14 and the winch in order to realize the overwind prevention function. More specifically, the mobile crane C includes a hydraulic circuit that supplies hydraulic oil to hydraulic actuators that drive the respective movable portions 63. The control unit 62 controls the supply of the hydraulic oil to the hydraulic actuator by switching the valves constituting the hydraulic circuit, and stops the operation of each movable unit 63.

The mobile crane C is mounted with various sensors. Specifically, a lift angle sensor 64 that detects information on the lift angle of the boom 14, an extension amount sensor 65 that detects information on the extension amount of the boom 14, and a tilt sensor 66 that detects information on the expansion and contraction of the tilt cylinder 17 mounted on the boom 16 are mounted. Information detected by these sensors 64 to 66 is input to the control unit 62.

However, as described later, in the boom extending/retracting operation, the boom 14 is moved up and down or extended and contracted so that the posture of the boom 14 is in an appropriate state. In addition, in the boom extending/retracting operation, the main hook 15m passes through (in other words, passes through) the bifurcated base end portion 16a of the boom 16 (specifically, between the pair of leg portions 16 c). Therefore, various parameters for determining the posture of the boom 14 and the like are stored in the control unit 62 in advance.

Specifically, the control unit 62 stores in advance a lift angle threshold value θ t, a boom extension threshold value Lt, an extension stop range Lr, and a tilt extension threshold value Tt. The lift angle threshold θ t is a threshold for distinguishing a descending state and an ascending state of the boom 14 from each other according to the lift angle of the boom 14.

That is, a state in which the lift angle of the boom 14 is smaller than the lift angle threshold θ t is referred to as a lowered state of the boom 14. On the other hand, a state in which the lift angle of the boom 14 is equal to or greater than the lift angle threshold θ t is referred to as a lift state of the boom 14. The lift angle of the boom 14 is obtained from the output of the lift angle sensor 64.

The boom extension threshold Lt is an extension of the boom 14 suitable for passing the main hook 15m through the boom base end portion 16a (specifically, between the pair of leg portions 16 c). In other words, the boom extension threshold Lt is a lower limit value of the extension of the boom 14 that can pass the main hook 15m through the boom base end portion 16a during the boom 16 unfolding operation. Further, in other words, the boom extension amount threshold Lt is the minimum extension amount necessary to separate the guide roller 31 from the guide 32.

That is, when the extension amount of the boom 14 is smaller than the boom extension amount threshold Lt, the guide roller 31 and the guide 32 are in a guide state of being engaged with each other. On the other hand, when the extension amount of the boom 14 is equal to or greater than the boom extension amount threshold Lt, the guide roller 31 and the guide 32 are in a non-guide state without being engaged with each other. The elongation of the boom 14 is acquired based on the output of the elongation sensor 65.

The extension stop range Lr is a range of the extension amount of the boom 14, and is set to the extension side of the boom extension threshold Lt. The extension stop range Lr is provided to stop extension of the boom 14 when the contracted boom 14 is extended to reach the boom extension amount threshold Lt. Such an extension stop range Lr has a width that takes into account a stop delay of the boom 14 (i.e., a distance extended from when an instruction to stop extension is issued to when the boom is actually stopped).

The lower limit of the extension stop range Lr is the extension amount of the boom 14 at a position (also referred to as a first position) where the engagement between the guide roller 31 and the guide 32 is released. On the other hand, the upper limit of the extension stop range Lr is the extension amount of the boom 14 set at the second position closer to the extension side of the boom 14 than the first position.

The second position is determined in consideration of a delay in stopping the boom 14 when the instruction to stop the extension of the boom 14 is issued at the first position (that is, a distance extended from the issuance of the instruction to stop the extension to the actual stop). The stop delay amount is appropriately determined according to the performance of the crane according to the model, such as the extension speed and the extension method.

The tilt elongation threshold Tt is a threshold value for distinguishing a descending state and an ascending state of the boom 16 according to the elongation of the tilt cylinder 17. That is, a state in which the extension amount of the tilt cylinder 17 is smaller than the tilt extension amount threshold value Tt is referred to as a lowered state of the boom 16. On the other hand, a state in which the extension amount of the tilt cylinder 17 is equal to or greater than the tilt extension amount threshold Tt is referred to as a raised state of the boom 16. The amount of extension of the tilt cylinder 17 is acquired from the output of the tilt sensor 66.

In the above configuration, the raising/lowering state of the boom 16 (i.e., which of the raising state and the lowering state is determined) is determined based on the amount of extension of the tilt cylinder 17. As another determination method, the raising/lowering angle of the boom 16 may be acquired from the output of a separately provided raising/lowering angle sensor, and the raising/lowering state of the boom 16 may be determined based on the raising/lowering angle.

Although depending on the configuration of the mobile crane C, for example, the heave angle threshold θ t is 20 °, the boom elongation threshold Lt is 1.2m, and the elongation stop range Lr is 1.2m to 1.3m (1.2 m. ltoreq. Lr < 1.3 m). The tilt elongation threshold Tt is an elongation of the tilt cylinder 17 when the lift angle of the boom 16 is 45 ° in a state where the lift angle of the boom 14 is 45 °.

Here, the lift angle of the boom 14 is an angle with respect to a horizontal plane passing through the central axis of the boom 14. The elongation of the boom 14 is relative to the elongation of the boom 14 in the fully contracted state. The lift angle of the boom 16 is an angle formed by the state suspended from the boom tip end portion 14c and the central axis of the boom 16 when the state is 0 °.

When any of the following conditions 1 to 4 (also referred to as a predetermined state in the crane) is satisfied, the control unit 62 releases (completely releases) or partially releases the overwind prevention function, thereby allowing the overwind state. This allows the boom to be operated in the overwound state during the boom extending/retracting operation.

When none of the conditions 1 to 4 is satisfied, the winding operation of the

hooks

15m and 15a is stopped (that is, the overwind prevention function is set) as usual. Thus, the overwinding prevention function is set in an unnecessary state, and overwinding caused by misoperation is prevented.

(Condition 1)

Lifting angle of the crane arm: less than a threshold angle of ascent and descent thetat

Elongation of the cargo boom: less than the threshold value Lt of the elongation of the cargo boom

The lifting angle of the boom 14 being smaller than the lifting angle threshold θ t means that the boom 14 is in a lowered state. Whether or not the lift angle of the boom lift angle 14 is smaller than the threshold value θ t is determined by the control unit 62 by comparing the lift angle acquired from the lift angle sensor 64 with the stored lift angle threshold value θ t.

Whether or not the extension amount of the boom 14 is smaller than the boom extension amount threshold Lt is determined by comparing the extension amount acquired from the extension amount sensor 65 with the stored boom extension amount threshold Lt in the control unit 62.

Specifically defined, condition 1 means: the boom 14 is in a lowered state, and the guide roller 31 is engaged with the guide 32 (hereinafter referred to as a guide state).

When the condition 1 is satisfied, the control unit 62 releases the overwind prevention function. That is, when the boom 14 is in the lowered state and the guide roller 31 is in the guide state of being engaged with the guide 32, the control unit 62 releases the overwind prevention function (i.e., allows the main hook 15m to move to the overwind position).

(Condition 2)

Elongation of the cargo boom: extension stop range Lr

When the condition 2 is satisfied, the control unit 62 releases the overwind prevention function in addition to the extension of the boom 14. In other words, when the condition 2 is satisfied, the control unit 62 allows the main hook 15m to move to the overwind position and prohibits the extension operation of the boom 14. That is, when the overwinding is detected, the boom 14 extension operation is stopped, but the rest of the operations (winch up, boom 14 down) are allowed.

(Condition 3)

Lifting angle of the crane arm: a rising and falling angle threshold value theta t or more

A tilting cylinder: is lower than the tilt elongation threshold value Tt

A lift angle of the boom 14 being equal to or greater than the lift angle threshold θ t means that the boom 14 is in a raised state. The tilt cylinder 17 being lower than the tilt elongation threshold Tt means that the boom 16 is in a lowered state. The tilt cylinder 17 of the present embodiment lowers the boom 16 by retracting. Therefore, the falling side of the tilt cylinder 17 with respect to the tilt elongation threshold value Tt means the contracted state of the tilt cylinder 17.

When the condition 3 is satisfied, the control unit 62 releases the overwind prevention function (i.e., allows the main hook 15m to move to the overwind position).

(Condition 4)

Elongation of the cargo boom: extension stop range Lr

A tilting cylinder: is lower than the tilt elongation threshold value Tt

When the condition 4 is satisfied, the control unit 62 releases the overwind prevention function in addition to the extension of the boom 14. In other words, when the condition 4 is satisfied, the control unit 62 allows the main hook 15m to move to the overwind position and prohibits the extension operation of the boom 14. That is, when overwinding is detected, the boom 14 stops extending, but the rest of the operations (winch up, boom 14 up) are allowed.

Table 1 is a table summarizing the above conditions and the release state of the overwind prevention function.

[ Table 1]

	Jib loading boom angle of bending down	Elongation of crane boom	Tilting cylinder	Overwinding prevention function
					Condition
1	Less than thetat	Less than Lt	-	All release
					Condition 2	Less than thetat	Lr	-	Partial release
Condition 3	Theta t or more	Less than Lt	Descend	All release
					Condition 4	Theta t or more	Lr	Descend	Partial release

(boom out operation)

Next, the overwinding prevention function will be described together with the boom extension work.

(1.1) As shown in FIG. 1, in the stored state of the boom 16, the boom 16 is stored along the side surface of the boom 14.

(1.2) first, the boom 14 is slightly extended. When the boom 14 is extended in a state where the

hooks

15m and 15a are wound up, the

hooks

15m and 15a are further wound up to be in an overwound state. However, since the condition 1 is satisfied in this state, the overwind prevention function is released. Therefore, the boom 14 can be extended.

When the elongation of the boom 14 reaches the elongation stop range Lr, the condition 2 is satisfied. Therefore, the overwind prevention function is released in addition to the extending operation of the boom 14. Since the

hooks

15m, 15a are already in the overwind state, the extension of the boom 14 is automatically stopped.

In other words, when the boom 14 is extended to the automatic stop, the extension amount of the boom 14 can be set to an extension amount suitable for the boom raising operation. The operator can easily perform the work without paying attention to the amount of extension of the boom 14.

(1.3) the boom 16 is then moved to a down position along the bottom surface of the boom 14. Specifically, when the hydraulic cylinder 42 of the first boom support member 40 is extended, the boom 16 rotates and moves to the lower holding position.

(1.4) then, the boom 14 is completely contracted to the state shown in fig. 2 and 3. By this operation, the boom connecting shaft 21 is fitted into the boom base end engaging portion 22. Subsequently, the pin 23 is inserted into the insertion hole of the boom base end engaging portion 22, and the boom base end engaging portion 22 is connected to the boom connecting shaft 21. Then, the tie bar 18 is connected to the tie bar connecting rod 19.

(1.5) subsequently, the main hook 15m is rolled up until the overwind state is achieved. Since the condition 1 is satisfied in this case, the overwind prevention function is released. Therefore, the main hook 15m can be rolled up to be in an overwound state. The main hook 15m is set to the overwound state in order to pass the main hook 15m through the arm base end portion 16a (specifically, between the pair of leg portions 16c) in the next step 1.6.

In this way, when the main hook 15m is rolled up so as to pass through the boom base end portion 16a, the overwinding prevention function is automatically released, and therefore, the main hook 15m can be rolled up to an overwind state (overwind position).

At this time, the operator can wind up the main hook 15m without consciously releasing the overwinding prevention function. Further, the worker can maintain the release state of the overwind prevention function without performing a special operation (for example, an operation of continuously pressing a switch or the like).

(1.6) subsequently, the boom 14 is completely raised (see fig. 8 (I)). Next, when the boom 14 is extended, the boom fixing pin 43 is disengaged from the pin boss 44, and the sub-pin 52 is disengaged from the sub-pin boss 53 (see fig. 8(I I)).

When the boom 14 is further extended, the guide roller 31 is guided by the guide 32, and the boom 16 is slowly pulled away from the bottom surface of the base end arm 14a (see fig. 8 (III)). Then, the boom 16 rotates about the boom connecting shaft 21, and hangs down from the boom tip end portion 14 c. At this time, the main hook 15m passes through the boom base end portion 16a (specifically, between the pair of leg portions 16 c).

In step 1.6, the main hook 15m is in an overwound state. However, since the condition 3 is satisfied in this case, the overwind prevention function is released. Therefore, the boom 14 can be extended. Further, when the extension amount of the boom 14 reaches the extension stop range Lr, the condition 4 is satisfied, and therefore, the overwind prevention function is released in addition to the extension of the boom 14.

Since the main hook 15m is already in the overwind state, the extension of the boom 14 is automatically stopped. In other words, when the boom 14 is extended to the automatic stop, the extension amount of the boom 14 can be set to an extension amount suitable for the boom raising operation. The operator can easily perform the work without paying attention to the amount of extension of the boom 14.

(1.7) Next, as shown in FIG. 9, the boom 14 is lowered until the boom tip portion 16b reaches the vicinity of the ground surface. Then, an auxiliary wire rope provided with an auxiliary hook 15a is passed through a pulley of the boom tip portion 16 b. Further, an auxiliary overwinding detection sensor 61a is attached to the boom tip portion 16 b.

(1.8) finally, as shown in fig. 10, when the tilt cylinder 17 is extended, tension is applied to the tie rod 18, so that the boom 16 is extended forward centering on the boom connecting shaft 21.

(arm storage work)

Next, the control of the control unit 62 will be described together with the boom storing operation.

(2.1) As shown in FIG. 10, in the extended state of the boom 16, the boom 16 is disposed forward of the boom tip portion 14 c.

(2.2) first, the boom 14 is raised to some extent, and the boom 14 is contracted to an extension amount suitable for the boom storing operation. The tilt cylinder 17 is contracted to a lower side than the tilt elongation threshold value Tt.

(2.3) subsequently, the main hook 15m is rolled up until the overwind state is achieved. Since the condition 3 is satisfied in this case, the overwind prevention function is released. Therefore, the main hook 15m can be rolled up to be in an overwound state.

The main hook 15m is set to the overwound state in order to pass the main hook 15m through the arm base end portion 16a (specifically, between the pair of leg portions 16c) in the next step 2.4. In this way, when the main hook 15m is rolled up so as to pass through the boom base end portion 16a, the overwinding prevention function is automatically released, and therefore, the main hook 15m can be rolled up to an overwind state (overwind position). At this time, the operator can wind up the main hook 15m without consciously releasing the overwinding prevention function.

(2.4) subsequently, the tilt cylinder 17 is completely lowered to relax the tension of the tie rod 18. As shown in fig. 9, the boom 16 is thus rotated about the boom connecting shaft 21 and suspended from the boom tip portion 14 c. At this time, the main hook 15m passes through the boom base end portion 16a (specifically, between the pair of leg portions 16 c).

(2.5) Next, the boom 14 is lowered until the tip end of the boom 16 reaches the vicinity of the ground. Then, an operation of detaching the auxiliary wire rope provided with the auxiliary hook 15a from the tip end portion of the boom 16 is performed. In addition, the auxiliary overwind detection sensor 61a is removed from the boom tip portion 16 b.

(2.6) subsequently, the boom 14 is completely raised (see fig. 8 (III)). When the boom 14 is contracted from this state, the guide roller 31 is guided by the guide 32, and the boom 16 is pulled against the bottom surface of the base end arm 14a (see fig. 8 (II)). When the boom 14 is further contracted, the boom 16 moves along the base arm 14a, the boom fixing pin 43 is inserted into the pin boss 44, and the sub pin 52 is inserted into the sub pin boss 53 (see fig. 8 (III)).

(2.7) Next, the boom 14 is lowered. Next, the pin 23 is pulled out from the insertion hole of the boom base end engagement portion 22, and the connection between the boom base end engagement portion 22 and the boom connecting shaft 21 is released (see fig. 2 and 3).

(2.8) Next, the boom 14 is slightly extended. Next, when the hydraulic cylinder 42 of the first boom support member 40 is contracted, the boom 16 is rotated from the lower holding position to the storage position. Finally, when boom 14 is fully retracted, boom 16 is stowed along the side of boom 14 as shown in fig. 1.

As described above, the control unit 62 releases the overwind prevention function under the specific conditions 1 to 4, and thus, the operation in the overwind state can be performed during the boom extension/retraction operation. In addition, in the conditions 1 and 2, it is assumed that the boom 14 is in a lowered state, and in the conditions 3 and 4, it is assumed that the boom 16 is in a lowered state. If these conditions are not satisfied, it is considered that the overwind prevention function is required for a normal suspension load operation or the like. Since the overwinding prevention function can be released only when necessary, overwinding due to erroneous operation can be prevented, and work efficiency can be improved.

(appendix)

As reference example 1 of a crane, a mobile crane includes a boom, a boom that can be extended from and stored in the boom, a main hook that hangs down from a tip end portion of the boom, and an overwinding prevention device that prevents overwinding of the main hook, the boom is configured such that the main hook passes through a base end portion of a bifurcated shape of the boom when extended from and stored in the boom, and the overwinding prevention device includes: the control unit stores a lift angle threshold for distinguishing a descending state and an ascending state of the boom according to a lift angle of the boom and a boom extension amount threshold which is an extension amount of the boom suitable for passing the main hook through a base end portion of the boom, and releases the overwind prevention function when the lift angle of the boom is smaller than the lift angle threshold and the extension amount of the boom is smaller than the boom extension amount threshold.

According to such reference example 1, in the case where the main hook is rolled up in order to pass through the base end portion of the boom, the overwinding prevention function is released, so that the main hook can be rolled up to be in an overwound state. Further, since the boom is in the lowered state as a condition, the overwind prevention function can be released only when necessary.

As reference example 2 of the crane, in addition to reference example 1, the control unit stores an extension stop range set to be closer to the extension side than the boom extension threshold, and when the lift angle of the boom is smaller than the lift angle threshold and the extension of the boom is within the extension stop range, the overwind prevention function is released in addition to the extension of the boom.

According to such reference example 2, when the boom is extended to the automatic stop, the extension amount of the boom can be set to an extension amount suitable for the boom raising operation, and therefore, the operator does not need to perform the operation while paying attention to the extension amount of the boom, and the operation is easy. Further, since the boom is in the lowered state as a condition, the overwind prevention function can be released only when necessary.

As reference example 3 of the crane, in addition to reference example 1 or reference example 2, a tilt cylinder that raises and lowers a boom with respect to a boom is provided, a control unit stores a tilt elongation threshold value for distinguishing a lowered state and a raised state of the boom according to an elongation of the tilt cylinder, and the overwind prevention function is released when a lift angle of the boom is equal to or more than the lift angle threshold value, an elongation of the boom is less than the boom elongation threshold value, and the elongation of the tilt cylinder is on a lower side than the tilt elongation threshold value.

According to reference example 3, in the case where the main hook is rolled up in order to pass through the base end portion of the boom, the overwinding prevention function is released, and the main hook can be rolled up to the overwind state. Further, since the boom is lowered, the overwinding prevention function can be released only when necessary.

As reference example 4 of the crane, in addition to any one of reference examples 1 to 3, the crane is characterized by including a tilt cylinder that raises and lowers a boom with respect to a boom, and the control unit stores: the overwind prevention function is released in addition to the boom extension when the lift angle of the boom is equal to or greater than the lift angle threshold, the boom extension is within the extension stop range, and the extension of the tilt cylinder is on the lower side than the tilt extension threshold.

According to reference example 4, when the boom is extended to the automatic stop, the extension amount of the boom can be set to an extension amount suitable for the boom raising operation, and therefore, the operator does not need to perform an operation while paying attention to the extension amount of the boom, and the operation is easy. Further, since the boom is lowered, the overwinding prevention function can be released only when necessary.

The disclosures of the specification, drawings and abstract of the specification contained in Japanese application 2016-.

Description of the symbols

C mobile crane

14 boom

15m main lifting hook

15a auxiliary hook

16 boom

16a boom base end part

16b boom tip

16c foot part

17 tilting cylinder

60 overwinding prevention device

61a auxiliary overwind detection sensor

61m main overwinding detection sensor

62 control part

63 moving part

64 lifting angle sensor

65 elongation sensor

66 tilt the sensor.

Claims

1. A crane is characterized by comprising:

a boom which is provided to be capable of lifting and retracting;

a main hook that is suspended from a front end portion of the boom and is capable of assuming a normal position in which a distance from the front end portion is greater than a first threshold value and an overwind position in which the distance is equal to or less than the first threshold value;

a boom having a pair of leg portions at a base end portion thereof and rotatably supported at a tip end portion of the boom, wherein the main hook located at the overwind position is capable of passing between the pair of leg portions;

a control unit having an overwind prevention function for preventing overwinding of the main hook, and switching between a set state and a release state of the overwind prevention function according to information on a lift angle of the boom and an extension amount of the boom; and

a guide device which has a first guide portion provided to the boom and a second guide portion provided to the boom, and guides the boom to move in accordance with expansion and contraction of the boom by engagement of the first guide portion and the second guide portion,

when the boom is extended from the contracted state, a position at which engagement between the first guide portion and the second guide portion is released is set as a first position, and a predetermined position on the extension side of the boom relative to the first position is set as a second position, the control portion performs any one of the following controls (1) to (4):

(1) in a state in which the overwind prevention function is set, when it is determined that the boom is in a lowered state based on the information and the first guide portion and the second guide portion of the guide device are in a guide state in which the boom is engaged with each other, the overwind prevention function is released;

(2) in a case where it is determined that the boom is in a lowered state based on the information in the setting state of the overwind prevention function, and the boom is extended by an amount equal to or more than the amount of extension up to the first position and equal to or less than the amount of extension up to the second position, a function other than prohibiting extension of the boom among the overwind prevention functions is canceled;

(3) in a state in which the overwind prevention function is set, when it is determined that the boom is in a raised state, the first guide portion and the second guide portion of the guide device are in a guide state in which they are engaged with each other, and the boom is in a lowered state based on the information, the overwind prevention function is released;

(4) in the setting state of the overwind prevention function, when it is determined that the boom is in the upward state, the boom is not less than the extension to the first position and not more than the extension to the second position, and the boom is in the downward state based on the information, the function other than the prohibition of the boom extension in the overwind prevention function is canceled.