JP4829763B2 - Crane safety equipment - Google Patents

Description

  The present invention relates to a crane safety device having a mast member such as a live mast.

  A crane having a live mast that is pivotally supported by a main frame so as to be able to move up and down behind the boom is known (see, for example, Patent Document 1). In this type of crane, the live mast pivots in the front-rear direction by winding or unwinding the hoisting rope that is hung between the rope sheave provided on the live mast and the rope sheave provided on the main frame. Undulate.

  The main frame is equipped with a hydraulic cylinder to support the live mast underneath, and when changing the crane from the working position to the transport position, the live mast is turned backward by winding the hoisting rope. When the crane is changed from the transport posture to the working posture, the live mast is pushed up by the hydraulic cylinder.

JP 2003-327389 A

  In the above-described crane, the crane is operated with the live mast in the working posture. At the time of crane work, the boom is supported by a rope passing through the live mast, so a compressive force acts on the live mast. When the live mast contacts the end of the hydraulic cylinder in a state where the compressive force is acting in this way, the live mast may be damaged.

The crane safety device according to the present invention is pivotally supported by the main frame so as to be pivotable in the longitudinal direction of the crane behind the boom with the pivot shaft as a fulcrum, and supports the boom hoisting rope. A mast member that rotates in the front-rear direction by winding or unwinding the rope, and a hydraulic cylinder that supports the mast member behind the crane with respect to the rotating shaft and pushes the mast member from a substantially horizontal transportation posture to a working posture; , A supporting member for connecting the mast member and the boom, a supporting force detecting means for detecting presence / absence of a boom supporting force acting on the mast member via the hoisting rope, and detecting that the boom supporting force is present by the supporting force detecting means And a cylinder control means for retracting the hydraulic cylinder.
The support force detecting means is configured as a switch device that detects whether or not the angle formed by the support member and the mast member is equal to or greater than a predetermined value, and when the angle formed is equal to or greater than the predetermined value, the switch device is activated to activate the boom support force. It is also possible to detect that there is.
An expansion / contraction detection means for detecting the contraction state of the hydraulic cylinder is provided, and when the boom detection force is detected by the support force detection means, and the non-degeneration state of the hydraulic cylinder is detected by the expansion / contraction detection means, the hydraulic cylinder is It can also be degenerated.
A mast angle detection means for detecting the rotation angle of the mast member is further provided, and the rotation angle greater than a predetermined value of the mast member is detected by the mast angle detection means in a state where the support force detection means detects no boom support force. If this is detected, the hydraulic cylinder can be extended.
When the rotation angle of the mast member reaches a predetermined value, it is possible to have stop means for stopping the rotation of the mast member by winding the boom hoisting rope.

  According to the present invention, when the boom supporting force acting on the mast member is detected via the hoisting rope, the hydraulic cylinder is brought into a degenerated state, so that the live mast is in a state where the compressive force is acting on the live mast. The live mast can be prevented from being damaged without contacting the end of the hydraulic cylinder.

Hereinafter, an embodiment of a crane safety device according to the present invention will be described with reference to FIGS.
FIG. 1 is an external side view of a crane to which a safety device according to an embodiment of the present invention is applied. An upper swing body 2 is mounted on the lower traveling body 1 so as to be capable of swinging. A boom 3 is pivotally supported at the front part of the upper swing body 2 so as to be pivotable in the front-rear direction, and a live mast 4 is pivotally supported at the rear of the boom 3 so as to be pivotable in the front-rear direction through the upper part of the swing body 2. Has been. The swivel body 2 includes a cab 5 supported at the front end of the main frame 200 (FIG. 2), a counterweight 6 supported at the rear end of the main frame 200, and a front drum 7 mounted on the main frame 200. A rear drum 8 and an undulating drum 9.

  A hook 11 is suspended from the tip of the boom 3 via a wire rope 10. The wire rope 10 is wound or unwound by driving a drum (for example, the front drum 7), whereby the hook 11 moves up and down. The tip of the boom 3 and the tip of the live mast 4 are connected via a pendant rope 12. Sheaves 13 and 14 (FIG. 2) are provided at the front end portion of the live mast 4 and the rear end portion of the main frame 200, respectively, and a hoisting rope 15 is hung between the sheave 13 and the sheave 14. The hoisting rope 15 is wound or fed out by driving the hoisting drum 9, whereby the live mast 4 is rotated in the front-rear direction, and the boom 3 is raised and lowered via the pendant rope 12.

  FIG. 2 is a side view showing a change in posture of the live mast 4 at the time of crane disassembling and assembling work. A bracket 201 is provided at the front end portion of the main frame 200, and a bracket 202 protrudes upward immediately after the bracket 201. The live mast 4 is pivotally supported on the bracket 202 via a pin P1 so as to be pivotable in the front-rear direction, and the boom 3 is pivotally supported on the bracket 201.

  Drums 7 to 9 are mounted on the rear side of the bracket 202 of the main frame 200, and a stopper 203 is provided on the rear side of the rearmost drum 9 so as to project upward. The live mast 4 is supported by the stopper 203 in the substantially horizontal storage state (FIG. 2C). Although not shown, the live mast 4 is composed of a pair of left and right pipe-shaped members having a substantially rectangular cross section, and the sheaves 13 and 14 are disposed between the left and right live masts 4. For this reason, when the posture of the live mast 4 is changed, the live mast 4 does not interfere with the sheaves 13 and 14.

  A hydraulic cylinder 20 is pivotally supported below the bracket 202 of the main frame 200 so as to be swingable. One end of a link 21 is connected to the tip of the hydraulic cylinder 20, and the other end of the link 21 is pivotally supported by the bracket 202 via a pin P1. A live mast support portion (not shown) protrudes from the distal end portion of the link 21 in a substantially horizontal direction toward the center in the width direction of the crane. This live mast support part contacts the lower surface of the live mast 4, and the thrust of the hydraulic cylinder 20 acts on the live mast 4 via the link 21.

  When the live mast 4 is turned over from the standing state of FIG. 2A to the retracted state of FIG. 2C, the hoisting drum 9 is driven to wind the hoisting rope 15. Thereby, the space | interval between sheaves 13 and 14 becomes narrow, and the live mast 4 rotates back. When the live mast 4 is in the retracted state, the hydraulic cylinder 20 is in an extended state, and the weight of the live mast 4 and a push-down force due to winding of the hoisting rope 15 act on the hydraulic cylinder 20 via the link 21. For this reason, the pressure oil in the bottom chamber of the hydraulic cylinder 20 is relieved via the relief valve 43 (FIG. 3), and the hydraulic cylinder 20 is degenerated as the live mast 4 rotates while supporting the live mast 4.

  The live mast 4 is provided with a mast angle detector 31, and the mast angle detector 31 detects a rotation angle of the live mast 4 (for example, the ground angle θ 1, hereinafter referred to as a mast angle). When the mast angle θ1 reaches the upper limit value θ1u (for example, 170 °) shown in FIG. 2B due to the winding of the hoisting rope 15, the automatic stop device is operated as will be described later, and the driving of the hoisting drum 9 is stopped. . Next, when the hydraulic circuit for driving the hydraulic cylinder 20 in FIG. 3 is switched and the bottom chamber of the hydraulic cylinder 20 is communicated with the tank, the support force by the hydraulic cylinder 20 becomes 0, so the live mast 4 falls due to its own weight. As shown in FIG. 2C, the live mast 4 is supported by the stopper 203 in a substantially horizontal (θ1 = 180 °) retracted state.

  In the present embodiment, the live mast 4 is gradually rotated backward while being supported by the hydraulic cylinder 20 via the link 21 by winding the hoisting rope 15 while the hydraulic cylinder 20 is extended. For this reason, the live mast 4 does not fall down vigorously, and the impact when the live mast 4 is turned over can be suppressed. In this case, although the bending force by the hoisting rope 15 with the contact point with the link 21 as a fulcrum acts on the live mast 4, the bending force itself is not so large, and the damage to the live mast 4 does not become a problem.

  On the other hand, during the crane work of FIG. 1, a compressive force in the direction of the arrow in the figure acts on the live mast 4 by the pendant rope 12 and the hoisting rope 15. At this time, if the crane operation is performed with the hydraulic cylinder 20 extended, the live mast 4 may come into contact with the link 21 when the live mast 4 is rotated backward. When the live mast 4 comes into contact with the link 21, a bending force acts on the live mast 4 on which a compressive force is acting, and thus the live mast 4 may be damaged. In order to prevent this, in the present embodiment, the hydraulic cylinder 20 is controlled as follows.

  FIG. 3 is a diagram showing the configuration of the safety device according to the present embodiment, and shows a hydraulic circuit for driving the hydraulic cylinder 20, a hydraulic circuit for driving the undulating drum 9, and a control block diagram for controlling these hydraulic circuits. ing. Pressure oil from the hydraulic pump 41 acts on the pair of left and right hydraulic cylinders 20 via the electromagnetic switching valve 42. The pressure acting on the hydraulic cylinder 20 is limited by the relief valve 43.

  The electromagnetic switching valve 42 is switched by a control signal from the controller 30 and controls the flow of pressure oil from the hydraulic pump 41 to the hydraulic cylinder 20. That is, when the electromagnetic switching valve 42 is switched to the position A, the pressure oil from the hydraulic pump 41 acts on the bottom chamber of the hydraulic cylinder 20 and the hydraulic cylinder 20 extends. When the electromagnetic switching valve 42 is switched to the position B, the pressure oil from the hydraulic pump 41 acts on the rod chamber of the hydraulic cylinder 20, and the hydraulic cylinder 20 is degenerated.

  Pressure oil from the hydraulic pump 44 acts on the hydraulic motor 9 a for driving the hoisting drum via the hydraulic switching valve 45. Pilot pressure from a hydraulic pressure source 47 corresponding to the operation amount of the operation lever 46 acts on the hydraulic pressure switching valve 45. With this pilot pressure, the hydraulic pressure switching valve 45 is switched to the winding side or the lowering side, the hydraulic motor 9a rotates forward or reverse, and the hoisting drum 9 is driven to wind or lower. Solenoid valves 48 and 49 are provided on the pilot pressure supply lines on the winding side and the lowering side of the hydraulic switching valve 45, respectively. The solenoid valves 48 and 49 are switched by a control signal from the controller 30 to prohibit the action of pilot pressure on the hydraulic switching valve 45 and forcibly stop the hydraulic motor 9a.

  The controller 30 includes an arithmetic processing unit having a CPU, ROM, RAM, and other peripheral circuits. The controller 30 includes a cylinder control unit 30A and a mast stop control unit 30B. The cylinder control unit 30A controls the electromagnetic switching valve 42, and the mast stop control unit 30B controls the electromagnetic valves 48 and 49. The controller 30 receives signals from the operation switch 32, mast angle detector 31, boom angle detector 33, load detector 34, pendant angle detector 35, cylinder storage detector 36, and relay box 37. Entered.

  The operation switch 32 is provided in the cab 5 and is operated by an operator to command expansion / contraction of the hydraulic cylinder 20. The boom angle detector 33 is provided on the boom 3 and detects the rotation angle of the boom 3 (for example, the ground angle θ3, hereinafter referred to as the boom angle). As shown in FIG. 2A, the load detector 34 is provided between the sheave 14 and the sheave 16 that is rotatably connected around the rotation axis of the sheave 14. The hoisting rope 15 is also wound around the sheave 16, and the load detector 34 detects the tension of the hoisting rope 15.

  The pendant angle detector 35 is a limit switch provided at the attachment part of the pendant rope 12 at the upper end of the live mast as shown in FIG. This limit switch is turned on when the angle θ2 formed by the live mast 4 and the pendant rope 12 is equal to or larger than a predetermined value θ2a, and is turned off when the angle θ2 is smaller than the predetermined value θ2a. Θ2 when the pendant rope 12 is connected to the boom 3 (for example, FIG. 1) is larger than θ2 when not connected (for example, FIG. 2). A predetermined value θ2a is set to a value (for example, 90 °) between θ2 in FIG. 1 and θ2 in FIG. As a result, it is possible to determine whether or not the pendant rope 12 and the boom 3 are connected by the on / off signal from the pendant angle detector 35, that is, whether or not the compressive force is acting on the live mast 4.

  The cylinder storage detector 36 is a limit switch provided on the bracket 202 below the link 21 as shown in FIG. This limit switch is turned on when the hydraulic cylinder 20 is retracted (stored state) and turned off when the hydraulic cylinder 20 is extended (non-stored state). Is the hydraulic cylinder 20 stored by a signal from the cylinder storage detector 36? Detect whether or not. The relay box 37 is provided on the boom 3. Signals from various sensors mounted on the boom 3 (for example, signals from a hook overwinding switch) are input to the controller 30 via the relay box 37.

  Processing in the cylinder control unit 30A will be described. FIG. 4 shows the processing contents in the cylinder control unit 30A when the operation switch 32 is not operated in a table form. When the operation switch 32 is operated, the electromagnetic switching valve 42 is switched according to the operation. That is, the electromagnetic switching valve 42 is switched to the position B when the operation switch 32 is extended, and is switched to the position A when the operation switch 32 is retracted. In FIG. 4, the wiring connection means whether or not the controller 30 provided on the revolving structure 2 and the relay box 37 provided on the boom 3 are connected via a harness. Is input to the controller 30, the answer is NO.

  As shown in FIG. 4, when the wiring connection is YES and the boom angle θ3 detected by the boom angle detector 33 is equal to or greater than a predetermined value θ3a (for example, 10 °), the controller 30 determines that the crane work mode. The crane work mode is a mode in which the boom 3 is lifted and supported from the ground, and tension (boom support force) is applied to the pendant rope 12. At this time, the controller 30 receives a signal from the cylinder storage detector 36. It is determined whether or not the hydraulic cylinder 20 is stored. If the hydraulic cylinder 20 is stored, the electromagnetic switching valve 42 is switched to the neutral position, and the flow of oil from the hydraulic pump 41 to the hydraulic cylinder 20 is stopped.

  On the other hand, when the hydraulic cylinder 20 is not stored in the crane work mode, the electromagnetic switching valve 42 is switched to the position B and the hydraulic cylinder 20 is degenerated. As a result, the hydraulic cylinder 20 enters the retracted state, and the link 21 can be prevented from coming into contact with the live mast 4 during crane work. When the wiring connection is NO and the boom angle θ3 is equal to or larger than the predetermined value θ3a, that is, when the boom 3 is connected but the harness of the relay box 37 is not connected, it is similarly determined as the crane work mode, If the cylinder 20 is not stored, the hydraulic cylinder 20 is retracted to be stored. Even when the boom angle detector 33 outputs an error signal, it is determined that the crane operation mode is set, and the hydraulic cylinder 20 is set in the retracted state.

  When the wiring connection is YES and the boom angle θ3 is less than the predetermined value θ3a, the hydraulic cylinder 20 is expanded or contracted according to a signal from the pendant angle detector 35. Here, when the pendant rope 12 is connected to the boom 3 and an ON signal is input from the pendant angle detector 35, the controller 30 determines that the crane disassembly / assembly operation mode is set. If the hydraulic cylinder 20 is stored in the crane disassembly / assembly operation mode, the electromagnetic switching valve 42 is switched to the neutral position, and the flow of pressure oil from the hydraulic pump 41 to the hydraulic cylinder 20 is stopped.

  When the hydraulic cylinder 20 is not stored in the crane disassembly / assembly operation mode, the electromagnetic switching valve 42 is switched to the position B, and the hydraulic cylinder 20 is degenerated. In this case, since the pendant rope 12 is connected to the boom 3 and the pendant angle detector 35 is turned on, a work for causing the boom 3 (crane assembly work) is expected. Even if it is less than the value θ3a, the hydraulic cylinder 20 is retracted to prepare for the work of causing the boom 3. By performing such processing, contact between the live mast 4 and the link 21 can be prevented even when the boom angle detector 33 is not mounted or when the boom angle detector 33 is out of order, for example. Similarly, when the wiring connection is NO, the boom angle θ3 is less than the predetermined value θ3a, and the pendant angle detector 35 is on, the hydraulic cylinder 20 is degenerated if the hydraulic cylinder 20 is not retracted. The storage state.

  On the other hand, when the wiring connection is YES, the boom angle θ3 is less than the predetermined value θ3a, and an off signal is input from the pendant angle detector 35, that is, when the pendant rope 12 is not coupled to the boom 3, The controller 30 determines that the live mast 4 shown in FIG. When the mast angle θ1 detected by the mast angle detector 31 is within a predetermined range θ1a to θ1b (for example, 80 ° to 90 °) in the live mast disassembly / assembly operation mode, the electromagnetic switching valve 42 is switched to the position A and the hydraulic pressure is changed. The cylinder 20 is extended. Thereby, the live mast 4 can be slowly turned backward while being supported by the hydraulic cylinder 20. If the mast angle θ1 is not within the predetermined range θ1a to θ1b, the electromagnetic switching valve 42 is switched to the neutral position.

  When the wiring connection is NO, the boom angle θ3 is less than the predetermined value θ3a, and the OFF signal is input from the pendant angle detector 35, the controller 30 performs the live mast disassembly / assembly operation mode or the live mast 4 described above. Judge as crane working mode. The crane operation by the live mast 4 is an operation of raising and lowering the live mast 4 by winding or unwinding the hoisting rope 15 and lifting the load 50 through the live mast 4 as shown in FIG. It is possible to attach and detach weights and the like. The crane operation by the live mast 4 is performed at least in a range where the mast angle θ1 is smaller than 90 °, and the mast angle θ1 is set in the crane operation mode by the live mast 4 as in the live mast disassembly / assembly operation mode. If it is within the range θ1a to θ1b, the electromagnetic switching valve 42 is switched to the position A and the hydraulic cylinder 20 is extended. If the mast angle θ1 is not within the predetermined range θ1a to θ1b, the electromagnetic switching valve 42 is switched to the neutral position.

  Next, processing in the mast stop control unit 30B will be described. When the hoisting rope 15 is wound up by operating the operating lever 46 and the mast angle θ1 reaches a predetermined upper limit value θ1u (for example, 170 °), the mast stop control unit 30B outputs a control signal to the electromagnetic valve 48, and the hoisting rope The winding operation of 15 is automatically stopped. The upper limit value θ1u is set to such a value that an excessive load is not applied to the live mast 4 due to excessive winding of the rope 15. Further, when the hoisting rope 15 is extended by the operation of the operation lever 46 and the mast angle θ1 reaches a predetermined lower limit value θ1d (for example, 25 °), a control signal is output to the electromagnetic valve 49 and the hoisting rope 15 is lowered. Stop operation automatically. The lower limit value θ1 is set to a value such that the hoisting rope 15 is not short in consideration of the length of the hoisting rope 15.

  Further, also within the above-described predetermined range θ1a to θ1b between the upper limit value θ1u and the lower limit value θ1d, the mast stop control unit 30B stops the operation of the hydraulic motor 9a according to the work mode. That is, in the crane work mode of θ3 ≧ θ3a, and in the crane disassembly / assembly work mode in which the pendant angle detector 35 is on with θ3 <θ3a, the storage state of the hydraulic cylinder 20 is detected by the cylinder storage detector 36. If the hydraulic cylinder 20 is not retracted when the hoisting drum 9 is driven to wind up, a control signal is output to the electromagnetic valve 48 and the hoisting operation is stopped. Thereby, the worker can recognize that the hydraulic cylinder 20 is not stored, and can reliably prevent the live mast 4 and the link 21 from contacting each other. On the other hand, if the hydraulic cylinder 20 is in the retracted state, a stop signal is not output to the solenoid valve 48, and in this case, a smooth winding operation can be realized.

  When the boom angle θ3 is less than the predetermined value θ3a and the pendant angle detector 35 is off, that is, in the live mast disassembly / assembly operation mode, the operation lever 46 is wound up so that the mast angle θ1 is within the predetermined range θ1a to θ1a. When it is within θ1b, a control signal is output to the electromagnetic valve 48, and the hoisting operation of the hoisting rope 15 is stopped. At this time, the hydraulic cylinder 20 starts the extending operation by the processing in the cylinder control unit 3A described above. For this reason, the hydraulic cylinder 20 can be reliably extended in a state where the mast angle θ1 is maintained within the predetermined range θ1 to θ2. In addition, since the hydraulic cylinder 20 extends while the live mast 4 is stopped, the worker can easily determine why the live mast 4 has been automatically stopped. To cancel the automatic stop of the live mast 4, it is only necessary to operate a release switch (not shown) provided in the vicinity of the operation lever 46, whereby the live mast 4 can be rotated beyond a predetermined range θ1a to θ1b. .

  In the crane operation mode with the live mast 4 (FIG. 5), the hydraulic motor 9a may be automatically stopped according to the work load within the range of the mast angle θ1 of θ1u <θ1 <θ1a. That is, the relationship between the working radius and the maximum load is set in the controller 30 in advance, the working radius is calculated based on the mast angle θ1 detected by the mast angle detector 31, and the load detector 34 detects the working radius. When the load reaches the maximum load corresponding to the working radius, a control signal may be output to the solenoid valves 48 and 49 to stop the hydraulic motor 9a.

  The operation of the safety device according to the present embodiment is summarized as follows. The live mast 4 is stored in a state of being turned backward as shown in FIG. From this state, the operating switch 32 is operated to extend the hydraulic cylinder 20 and the operating lever 46 is operated to feed the hoisting rope 15. As a result, the live mast 4 is pushed up by the thrust of the hydraulic cylinder 20 and stands on the main frame. When the hydraulic cylinder 20 is extended to the maximum, the mast angle θ1 is smaller than 90 °. When the hoisting rope 15 is extended in this state, the live mast 4 is turned forward by its own weight, and the mast angle θ1 is gradually decreased. Become.

  As shown in FIG. 7, when the mast angle θ1 reaches the lower limit value θ1u, the winding operation of the hoisting drum 9 is stopped by switching the electromagnetic valve 49, and the live mast 4 is automatically stopped. In this state, as shown in FIG. 8, the pendant rope 12 is connected to the boom tip, and the harness 51 from the boom angle detector 33 and the relay box 37 is connected to the controller 30. Next, the operating lever 46 is operated to wind up the hoisting rope 15. As a result, the pendant rope 12 is pulled as shown in FIG. 9, and the pendant angle detector 35 is turned on. For this reason, the hydraulic cylinder 20 is degenerated and stored by the process in the cylinder control unit 30A described above, and contact between the live mast 4 and the link 21 can be prevented. In this state, even if the mast angle θ1 falls within the predetermined range θ1a to θ1b, the live mast 4 can perform the crane operation without automatically stopping.

  On the other hand, when the live mast 4 is stored, the pendant rope 12 is removed from the boom 3 with the boom 3 grounded. As a result, the pendant angle detector 35 is turned off. In this state, the operator operates the operation lever 46 to drive the hoisting drum 9 so as to rotate the live mast 4 backward. As shown in FIG. 10, when the mast angle θ1 reaches a predetermined value θ1a, the live mast 4 is automatically stopped by the process in the mast stop control unit 30B and the hydraulic cylinder is processed by the process in the cylinder control unit 30A. 20 expands. When the hydraulic cylinder 20 is extended, the worker drives the hoisting drum 9 to wind up and lifts the live mast 4 backward while releasing the automatic stop of the hoisting drum 9 until the mast angle θ1 reaches a predetermined value θ1b. When the mast angle θ1 exceeds the predetermined value θ1b, the automatic stop canceling operation is stopped. Thereafter, while the live mast 4 is supported by the hydraulic cylinder 20, the live mast 4 is rotated rearward to bring the live mast 4 into a retracted state.

According to the above embodiment, the following effects can be obtained.
(1) The angle θ2 between the live mast 4 and the pendant rope 12 is detected by the pendant angle detector 35, and when θ2 ≧ θ2a, that is, when the compressive force is acting on the live mast 4 via the pendant rope 12. The hydraulic cylinder 20 is degenerated. Thereby, it can prevent that the live mast 4 contacts the link member 21 at the time of a crane work, and can prevent damage to the live mast 4.

(2) Since the pendant angle detector 35 is constituted by a limit switch, it is possible to accurately detect whether or not a compressive force is acting on the live mast 4 via the pendant rope 12. That is, the tension of the hoisting rope 15 increases not only in the work causing the boom 3 (FIG. 9) but also in the crane work (FIG. 5) using the live mast 4. Although it is difficult to detect, the ON / OFF signal of the pendant angle detector 35 can easily detect this.

(3) Since the storage of the hydraulic cylinder 20 is detected by the cylinder storage detector 36, the storage state of the hydraulic cylinder 20 can be reliably detected, and the safety in cylinder control is increased. Further, since the hydraulic cylinder 20 is degenerated only when not stored, it is possible to prevent wasteful flow of pressure oil to the hydraulic cylinder 20.
(4) When the pendant angle detector 35 is off and the mast angle θ1 is within the predetermined range θ1a to θ1b, the hydraulic cylinder 20 is expanded, so that the live mast 4 is supported by the hydraulic cylinder 20 and the storage posture is set. Yes, the live mast 4 can be turned over slowly.
(5) Since the rotation of the live mast 4 is stopped when the mast angle θ1 becomes equal to or greater than the predetermined value θ1a, the live mast 4 can be turned backward after the hydraulic cylinder 20 is reliably extended.
(6) Since the hydraulic cylinder 20 automatically expands and contracts in response to signals from the boom angle detector 33, the pendant angle detector 35, the cylinder storage detector 36, and the mast angle detector 31, Problems such as incorrect operation can be solved.

  In the above embodiment, the live mast 4 as the mast member and the boom 3 are connected via the pendant rope 12, and the boom 3 is supported via the hoisting rope 15 and the pendant rope 12. Support members (for example, pendant links) can also be used. The pendant angle detector 35 is provided as a switch device. The switch device detects the presence or absence of boom support force or the boom angle θ3 detected by the boom angle detector 33. Not limited to this. Regardless of the boom angle θ3, the boom supporting force may be detected only by a signal from the pendant angle detector 35. When the boom support force is detected, the controller 30 outputs a control signal to the electromagnetic switching valve 42 to retract the hydraulic cylinder 20, but the configuration of the cylinder control means is not limited to this. Although the sheave 14 around which the hoisting rope 15 is hung is provided in the main frame 200, a stay may be provided behind the live mast 4 and the sheave 14 may be provided in the stay.

  Although the storage state of the hydraulic cylinder 20 is detected by the cylinder storage detector 36, any expansion / contraction detection means may be used. Although the mast angle θ1 is detected by the mast angle detector 31, any mast angle detecting means may be used. When the mast angle θ1 reaches the predetermined value θ1a, the controller 30 switches the electromagnetic valve 48 to automatically stop the hydraulic motor 9a. However, the stop means may have any configuration. In the above, although it applied to the crane which has a live mast as a mast member, it is applicable similarly to the crane which has another mast member. That is, the present invention is not limited to the crane safety device of the embodiment as long as the features and functions of the present invention can be realized.

The external appearance side view of the crane with which the safety device which concerns on embodiment of this invention is applied. The side view which shows the attitude | position change of the live mast at the time of the disassembly / assembly operation | work of a crane. The figure which shows the structure of the safety device which concerns on this Embodiment. The figure which shows the processing content in the cylinder control part of FIG. The figure which shows the example of the crane work by a live mast. The figure which shows 1 operation | movement of the disassembly / assembly operation | work of the crane which concerns on this Embodiment (the 1). The figure which shows 1 operation | movement of the disassembly / assembly operation | work of the crane which concerns on this Embodiment (the 2). The figure which shows 1 operation | movement of the disassembly / assembly operation | work of the crane which concerns on this Embodiment (the 3). The figure which shows 1 operation | movement of the disassembly / assembly operation | work of the crane which concerns on this Embodiment (the 4). The figure which shows 1 operation | movement of the disassembly / assembly operation | work of the crane which concerns on this Embodiment (the 5).

Explanation of symbols

3 Boom 4 Live mast 12 Pendant rope 15 Undulating rope 20 Hydraulic cylinder 30 Controller 31 Mast angle detector 33 Boom angle detector 35 Pendant angle detector 36 Cylinder storage detector 42 Solenoid switching valve 48, 49 Solenoid valve

Claims (5)

With the pivot shaft as a fulcrum, it is pivotally supported by the main frame so that it can pivot in the longitudinal direction of the crane behind the boom, and supports the boom hoisting rope, and the wind hoisting rope is wound or unwound in the longitudinal direction. A mast member that rotates to
A hydraulic cylinder that supports the mast member behind the crane relative to the pivot shaft and pushes the mast member from a substantially horizontal transportation posture to a working posture;
A supporting member for connecting the mast member and the boom, and a supporting force detecting means for detecting presence or absence of a boom supporting force acting on the mast member via the hoisting rope;
A crane safety device comprising: cylinder control means for retracting the hydraulic cylinder when the support force detection means detects that the boom support force is present. The crane safety device according to claim 1,
The support force detecting means includes a switch device that detects whether an angle formed by the support member and the mast member is a predetermined value or more, and the switch device is activated when the formed angle is a predetermined value or more. And detecting the presence of the boom supporting force. In the crane safety device according to claim 1 or 2,
Expansion / contraction detection means for detecting the contraction state of the hydraulic cylinder;
The cylinder control means degenerates the hydraulic cylinder when it is detected by the support force detection means that there is a boom support force and the expansion / contraction detection means detects a non-degenerate state of the hydraulic cylinder. Features crane safety device. In the crane safety device according to any one of claims 1 to 3,
Mast angle detecting means for detecting a rotation angle of the mast member;
When the cylinder control means detects that the boom support force is absent by the support force detection means, and the mast angle detection means detects a rotation angle of a predetermined value or more of the mast member, the cylinder control means A crane safety device characterized by extending a hydraulic cylinder. The crane safety device according to claim 4,
A crane safety device comprising stop means for stopping rotation of the mast member due to winding of the boom hoisting rope when the rotation angle of the mast member reaches the predetermined value.

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