JP5438347B2 - crane - Google Patents

Description

  The present invention relates to a crane having a jib.

  Conventionally, a crane configured by further attaching a luffing jib to the tip of a crane boom is known.

  The crane having the luffing jib is attached to the tip of the boom so that the luffing jib can be raised and lowered, and the hook block is suspended from the tip of the luffing jib, so that the lifting work with a high lift and a large working radius is possible.

  In a crane having this luffing jib, if the undulation angle is increased in the direction in which the luffing jib is raised, the rotational moment due to the weight of the mast or wire that supports the luffing jib increases, and the luffing jib may fall backward .

  For this reason, for example, Patent Document 1 discloses a configuration in which a fall prevention cylinder is bridged between the boom and the luffing jib and the cap side and the head side of the fall prevention cylinder are communicated with each other by a counter balance valve.

  According to this configuration, when the rotational moment in the rear increases, the fall can be prevented by switching the pressure of the fall prevention cylinder from the low pressure to the high pressure and pushing the luffing jib back forward. In addition, it is possible to prevent resistance due to an increase in pressure during the undulation operation, and to reduce the amount of pressure oil during the overturning operation, thereby reducing the pump capacity.

Japanese Patent Laid-Open No. 11-263589

  However, in the above-described conventional crane, when the rotation moment in the rear is reduced and the pressure of the overturn prevention cylinder is switched from high pressure to low pressure, the tension of the holding wire is suddenly released and the boom is bent. There was a case where a shake occurred.

  Therefore, an object of the present invention is to provide a crane that can reduce the swinging of the jib while preventing the jib from tipping over.

  To achieve the above object, a crane according to the present invention includes a boom, a jib that can be raised and lowered at a tip of the boom, a holding wire that holds the jib tilted forward to cause the jib to be moved backward, and A crane having a boom and a fall prevention cylinder that spans the jib and drives the jib forward, and prevents the fall when the tension of the holding wire decreases to a predetermined allowable tension. The oil discharge path from the hydraulic chamber of the overturn prevention cylinder is sealed after pressurizing the hydraulic chamber that is to be laid down when the cylinder is pressurized to bring the tension of the holding wire to a predetermined stable tension. It is characterized by.

  Thus, when the tension of the holding wire decreases to a predetermined allowable tension, the crane of the present invention pressurizes the hydraulic chamber on the side to fall when the overturn prevention cylinder is pressurized, and the tension of the holding wire Is set to a predetermined stable tension, and the oil drainage path from the hydraulic chamber serving as the side to be laid down when the fall prevention cylinder is pressurized is sealed.

  In this way, by adjusting the tension of the holding wire and restricting the oil drainage from the hydraulic chamber on the side to fall down when the overturn prevention cylinder is pressurized, it is not possible to actively drain the oil. It is possible to suppress a sudden pressure change in the hydraulic chamber that is the side to be laid down during pressure. For this reason, since the tension | tensile_strength of a holding wire is not released rapidly, a boom does not bend and it does not touch a load.

It is explanatory drawing explaining the structure of the crane of this invention. It is explanatory drawing explaining the whole structure of a crane. It is a hydraulic circuit diagram of a crane. It is explanatory drawing which showed the change of the tilt angle. It is a flowchart explaining the control procedure of a fall prevention cylinder. It is a table | surface explaining switching of ON / OFF of each solenoid. 6 is a graph showing the relationship between the tension of the holding wire and the pressure of the overturn prevention cylinder. It is the graph which showed the relationship between the tilt angle and the tension | tensile_strength of a holding wire.

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

  First, the whole structure of the crane 1 of this invention is demonstrated using FIG.

  The crane 1 of the present invention is an all-terrain crane, and as shown in FIG. 2, a vehicle body 10 having a traveling function, a swivel base 11 that can be horizontally swiveled on the vehicle body 10, and a swivel base 11 that can be raised and lowered. A boom 2 to be attached and a luffing jib 3 as a jib attached to the tip of the boom 2 so as to be raised and lowered are provided.

  In addition, although a present Example demonstrates the case where it applies to an all terrain crane as the crane 1, it is applicable to what kind of crane as long as it is a crane which has a jib and has a cylinder for a fall prevention.

  Inside the vehicle body 10, a safety device 70 (see FIG. 2) for monitoring the total center of gravity position and overturning moment is arranged so that the crane 1 does not fall over, and controls the operation of the back stopper cylinder 5 described later. The safety device 70 can be configured by a general-purpose microcomputer having a central processing unit, a main storage device, an auxiliary storage device, and the like.

  The boom 2 is formed to be telescopic by stacking steel cylinders in a nested manner, and the base portion of the main body 20 is attached to the rotating shaft of the swivel base 11 to expand and contract the hoisting cylinder 21. Then rise and fall.

  The luffing jib 3 as a jib is used to increase the working radius, is formed as a lattice jib in which steel materials are assembled in a truss shape, and is attached to the pivot shaft at the tip of the boom 2 so as to be raised and lowered. Yes.

  Further, a lifting wire 40 is hung on the sheave 31 attached to the tip of the luffing jib 3. A hook is attached to one tip of the lifting wire 40, and the other end is disposed on the swivel base 11. The hoisting winch 66 is wound around.

  Masts 61 and 62 are erected on the back side of the luffing jib 3, and links 63 are provided between the mast 61 on the front end side and the luffing jib 3, and between the mast 61 on the front end side and the mast 62 on the rear end side. 64 are built.

  In addition, a holding wire 41 for holding the luffing jib 3, the masts 61 and 62, the links 63 and 64, etc. is hung on the back side of the integrated luffing jib 3. One end of the holding wire 41 is attached to the tip of the luffing jib 3, and the other end is wound around a holding winch 67 arranged on the swivel base 11.

  Further, in the holding wire 41 of this embodiment, a tension measuring device 65 for measuring the tension acting on the holding wire 41 is installed between the mast 62 on the rear end side and the holding winch 67.

  For example, when raising the luffing jib 3 so that the tilt angle θ is reduced, the holding wire 41 is wound up by the holding winch 67, and when lying down so that the tilt angle θ is increased, the holding winch 67 is used. The holding wire 41 is sent out.

  A back stopper cylinder 5 serving as a fall prevention cylinder is bridged between the tip of the boom 2 and the root of the luffing jib 3 of the present embodiment in order to prevent the luffing jib 3 from falling backward. Has been. The cap side 52 is attached to the luffing jib 3, and the head side 53 is attached to the boom 2.

  The back stopper cylinder 5 rises when the luffing jib 3 is raised so as to reduce the tilt angle θ, and when the overall center of gravity position (described later) of the luffing jib 3 is located behind the rotation axis of the luffing jib 3, 3 is driven forward (in the direction of increasing the tilt angle θ) and pushed back.

  Here, the total center-of-gravity position of the entire luffing jib 3 refers to the action point of the resultant force of gravity of the luffing jib 3, the masts 61 and 62, the links 63 and 64, and the holding wire 41.

  Further, the tilt angle θ is an upper angle formed by the axis of the boom 2 and the axis of the luffing jib 3. Furthermore, with respect to the boom 2 and the luffing jib 3, the front means the side where the hook and the load are located, and the rear means the opposite side to the direction where the hook and the load are located.

  Next, a hydraulic circuit for controlling the back stopper cylinder 5 of the crane 1 of this embodiment will be described with reference to FIG.

  The inside of the back stopper cylinder 5 is divided into a head side 53 on which the rod 51 is arranged and a cap side 52 on the opposite side across the piston, and each is connected to a pump 88 and a tank 89, and as a whole A differential circuit is configured.

  A relief valve 81, a cap-side oil discharge valve 82, and a counter balance valve 83 are connected to a circuit on the cap side 52, which is a hydraulic chamber on the side where the luffing jib 3 is laid down during pressurization.

  The relief valve 81 is for maintaining the pressure on the cap side 52 at a toppling prevention pressure H, which will be described later. The relief valve 81 is a normally closed valve that presses a piston with a spring to close the valve, and between the cap side 52 and the tank 89. Is arranged. When the hydraulic pressure in the circuit on the cap side 52 reaches the overturning prevention pressure H, which is the set pressure, the piston is pushed against the spring reaction force, the valve is opened and hydraulic oil flows to automatically increase the pressure. maintain.

  The cap side oil discharge valve 82 is used to positively discharge the hydraulic oil on the cap side 52 to the tank 89 side, and the solenoid is activated only when an instruction is given from the safety device 70 as the control means. It is a normally closed valve that moves and opens the valve, and is disposed between the cap side 52 and the tank 89.

  Further, the counter balance valve 83 is provided to adjust the control speed, and is configured to introduce hydraulic oil on the cap side 52 to the head side 53 by detecting the pressure on the head side 53 and opening and closing. Has been.

  Similarly, a relief valve 86, a head side oil discharge valve 85, and a counter balance valve 84 are connected to a circuit on the head side 53, which is a hydraulic chamber on the side that raises the luffing jib 3 during pressurization. Yes.

  The relief valve 86 is for maintaining the pressure on the head side 53, and is a normally closed valve that closes the valve by pressing a piston with a spring, and is disposed between the head side 53 and the tank 89.

  The head side oil discharge valve 85 is used to positively discharge the hydraulic oil on the head side 53 to the tank 89 side, and the solenoid is activated only when an instruction is given from the safety device 70 as the control means. It is a normally closed valve that moves and opens the valve, and is disposed between the head side 53 and the tank 89.

  Further, the counter balance valve 84 is provided to adjust the control speed, and is configured to introduce the hydraulic oil on the head side 53 to the cap side 52 by detecting the pressure on the cap side 52 and opening and closing. Has been.

  In the hydraulic circuit of the present embodiment, a circulation valve is provided as a path that bypasses between the pump 88 and the differential circuit and between the tank 89 and the differential circuit as a path different from the above-described differential circuit. A circulation circuit having 87 is provided.

  This circulation circuit is a circuit for operating the constant capacity pump 88 and returning the hydraulic oil to the tank 89 without energy loss without passing through the differential circuit. When an instruction is given to the circulation valve 87 from the safety device 70 as a control means, hydraulic oil flows into the circulation circuit, and when no instruction is given, the circulation circuit is shut off.

  Next, the effect | action of the crane 1 of a present Example is demonstrated using FIG. In this embodiment, the case where the boom 2 is longer than the predetermined holding length and seals the oil drainage path (exceeding the predetermined length in FIG. 6) will be described. The hydraulic pressure maintenance control described here is mainly executed in the safety device 70 as a control means.

  First, the luffing jib 3 is lifted to reduce the tilt angle θ (θb1 to θc in FIG. 4), and when the tension T of the holding wire 41 measured by the tension measuring device 65 reaches the allowable tension T1 (step S1). To S3), the raising of the luffing jib 3 is stopped, and the cap side 52 of the back stopper cylinder 5 is pressurized to a predetermined fall prevention pressure H (step S4).

  In this case, in the hydraulic circuit, as shown in the table of FIG. 6 (back tension tension = none, BSC operation state = stop / extend), the cap-side oil supply valve 90 is ON, the cap-side oil discharge valve 82 is OFF, the head The side drain valve 85 is turned off and the circulation valve 87 is turned off.

  Therefore, the hydraulic oil is supplied to the cap side 52 of the back stopper cylinder 5 and the hydraulic pressure gradually increases until the predetermined fall prevention pressure H is reached (from c to d in FIG. 7). When it reaches, the relief valve 81 is opened, and the working oil returns to the tank 89 through the oil discharge path (vent circuit).

  Subsequently, the luffing jib 3 is laid down to increase the tilt angle θ (from θd to θa in FIG. 4), and the tension T of the holding wire 41 measured by the tension measuring device 65 increases, so that the marginal tension as a stable tension is increased. When TA is reached (steps S5 to S7), the oil drainage path on the cap side 52 of the back stopper cylinder 5 is sealed and the circulation circuit is connected (steps S8 and S9).

  In this case, in the hydraulic circuit, as shown in the table of FIG. 6 (back tension tension = present, BSC operation state = extension), the cap-side oil supply valve 90 is ON, the cap-side oil discharge valve 82 is OFF, the head-side oil discharge is performed. The oil valve 85 is turned on and the circulation valve 87 is turned on.

  Accordingly, the hydraulic oil is fed to the cap side 52 of the back stopper cylinder 5 to increase the tension T while maintaining the predetermined overturn prevention pressure H (from d to a in FIG. 7), and the marginal tension TA as a stable tension. (A in FIG. 7), the circulation circuit is connected while the oil drainage path on the cap side 52 of the back stopper cylinder 5 remains sealed.

  When the holding wire 41 is further loosened and the luffing jib 3 is laid down to increase the tilt angle θ (θa to θb1 in FIG. 4), the pressure of the back stopper cylinder 5 gradually decreases to a low pressure L, and the holding is performed. The tension T of the wire 41 also slowly decreases over time and reaches the relaxation tension T3 (a to b1 in FIG. 7, step S10). In this case, the hydraulic circuit remains the same.

  Subsequently, when the holding wire 41 is loosened and the luffing jib 3 is laid down to increase the tilt angle θ (θb1 to θe in FIG. 4), the forward moment increases due to the posture change. The tension T of the holding wire 41 gradually increases with the low pressure L kept (step S11).

  Further, in the above-described hydraulic pressure maintenance control, when a hysteresis is provided in the relationship of “tension of holding wire 41—output of back stopper cylinder (BSC)” in FIG. 7, that is, when tipping prevention pressure H is maintained from θd to θa. However, the fall prevention pressure H is not necessarily maintained.

  That is, when the tension T of the holding wire 41 becomes the holding tension TA ′ as the stable tension due to the pressing by the fall prevention pressure H, the above-described steps S5 to S7 are omitted, and the control of steps S8 to S11 is executed. May be.

  Next, the effect of the crane 1 of the present invention will be described.

  (1) As described above, the crane 1 according to the present embodiment has a hydraulic pressure that is to be laid down when the back stopper cylinder 5 is pressurized when the tension T of the holding wire 41 decreases to a predetermined allowable tension T1. The cap side 52 as a chamber is pressurized and the luffing jib 3 is driven and pushed back, so that the tension T of the holding wire 41 is set to a predetermined stable tension (margin tension TA and holding tension TA ′), and the back stopper cylinder 5 The oil drainage path from the cap side 52 of the engine is sealed.

  Thus, since the luffing jib 3 is pushed forward by setting the tension T of the holding wire 41 to a stable tension, the luffing jib 3 can be prevented from falling backward.

  Then, the tension T of the holding wire 41 is adjusted to a stable tension, and the oil draining from the cap side 52 of the back stopper cylinder 5 is limited to prevent the oil from being actively drained. Can be suppressed.

  For this reason, the tension T of the holding wire 41 is not suddenly released from the stable tension to the relaxation tension T2 (T3), the boom 2 is not suddenly bent, and the load is not touched.

  That is, as shown in FIG. 7, conventionally, when the pressure of the back stopper cylinder 5 is switched from the overturning prevention pressure H to the low pressure L, the tension T of the holding wire 41 is relaxed from the surplus tension TA in a short time (instantaneously). By reducing the tension to T2, the boom 2 bends rapidly, so that the load position suddenly changed and a load swing occurred.

  On the other hand, even in this embodiment, when switching from the overturning prevention pressure H to the low pressure L, the tension T decreases from the surplus tension TA or the holding tension TA ′ to the relaxation tension T3, but this tension change takes a long time. Since it occurs slowly, there will be no significant vibration.

  In the above case, since the luffing jib 3 is driven and pushed back by applying the anti-falling pressure H to the back stopper cylinder 5, a part of the lifting performance is sacrificed. In the enlarged state, the back stopper cylinder 5 has a low pressure, so there is almost no problem.

  (2) When the tension T of the holding wire 41 decreases to a predetermined allowable tension T1, the cap side 52 of the back stopper cylinder 5 is pressurized with a predetermined overturn prevention pressure H, and then the back stopper The oil discharge path from the cap side 52, which is a hydraulic chamber serving as a side on which the luffing jib 3 is laid down when the cylinder 5 is pressurized, is sealed.

  In this way, by adjusting the pressure of the back stopper cylinder 5 and restricting oil drainage from the cap side 52 of the back stopper cylinder 5 so as not to actively drain oil, Sudden pressure change can be suppressed. For this reason, since the tension T of the holding wire 41 is not suddenly released, the boom 2 is not suddenly bent and the load is not touched.

  (3) Further, when the cap side 52 of the back stopper cylinder 5 is pressurized with a predetermined overturn prevention pressure H, the tension T of the holding wire 41 is increased to a marginal tension TA as a predetermined stable tension. Since the oil drainage path from the cap side 52 of the back stopper cylinder 5 is sealed, the tension T can be measured and the risk of falling can be directly detected, so that the crane 1 with higher safety can be obtained.

  In addition, it is possible to prevent the control from looping in a short time by maintaining the back stopper cylinder 5 at the tipping prevention pressure H and maintaining the tension T until it reaches the surplus tension TA to provide hysteresis.

  (4) The oil discharge path from the cap side 52 of the back stopper cylinder 5 is sealed by a cap side oil discharge valve 82 disposed at a predetermined position, and the oil supply path to the cap side 52 is a circulation valve. An oil drain path from the cap side 52 is connected to the downstream side of the cap side oil discharge valve 82 via a circulation circuit having 87.

  Therefore, even if the oil discharge path is sealed by the cap side oil discharge valve 82, the hydraulic oil can be circulated by passing through the circulation circuit, so that a delay in response of the back stopper cylinder 5 can be prevented.

  That is, the pump 88 that feeds hydraulic oil is normally disposed inside the vehicle body 10, and therefore the distance from the pump 88 to the back stopper cylinder 5 is long.

  If it does so, if it comprises so that hydraulic oil may be sent by switching ON / OFF of the pump 88 for every operation | movement, operation | movement of the back stopper cylinder 5 will be delayed by the time which oil supply requires.

  On the other hand, if the hydraulic oil is circulated in a high pressure state via the relief valve 81 with the pump 88 kept ON, the temperature of the hydraulic oil rises and energy loss increases.

  Therefore, if the pump 88 is kept ON and a circulation circuit with less resistance is provided and the hydraulic oil is circulated through the circuit, such operation delay and energy loss do not occur.

  (5) When the length of the boom 2 is equal to or longer than the predetermined holding length, the boom 2 is short if the oil drainage path from the cap side 52 of the back stopper cylinder 5 is sealed. In this case, since the oil can be drained positively, it is possible to prevent the lifting performance from being lowered by continuously pressing the luffing jib 3 with the back stopper cylinder 5.

  That is, pushing the luffing jib 3 with the back stopper cylinder 5 means that a load is applied to the luffing jib 3 downward, so that the lifting performance of the luffing jib 3 is lowered accordingly.

  Therefore, when the boom 2 is short and the bending is small enough not to cause a problem, the suspension performance of the luffing jib 3 can be improved correspondingly by stopping pressing the back stopper cylinder 5.

  The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to the present invention. included.

  For example, in the above-described embodiment, the control for returning the oil to the tank 89 by reducing the resistance of the hydraulic oil by providing a circulation circuit while sealing the oil drain path from the cap side 52 of the back stopper cylinder 5 has been described. The back stopper cylinder 5 may be held at the overturning prevention pressure H via the relief valve 81 without providing a circulation circuit.

  In the above embodiment, the case where the back stopper cylinder 5 as the overturn prevention cylinder is stretched over the boom 2 and the luffing jib 3 to pressurize the cap side 52 to a predetermined stable tension has been described. The present invention is not limited, and when the overturn prevention cylinder is spanned downward, the head side may be pressurized to a predetermined stable tension.

1 Crane 2 Boom 3 Roughing jib (jib)
41 Holding wire 5 Back stopper cylinder
52 Cap side 65 Tension measuring instrument 81, 86 Relief valve 82 Cap side oil release valve 85 Head side oil release valve 87 Circulation valve 90 Cap side oil supply valve L Low pressure H Fall prevention pressure T Tension T1 Allowable tension T2, T3 Relaxation tension TA Margin (stable tension)
TA 'Holding tension (stable tension)
θ Tilt angle

Claims (5)

A boom, a jib that can be raised and lowered at the tip of the boom, a holding wire that holds the jib tilted forward so as to cause it to move rearward, and the boom and the jib that spans the jib forward A crane having a fall prevention cylinder for driving,
When the tension of the holding wire decreases and reaches a predetermined allowable tension, the tension of the holding wire is set to a predetermined stable tension by pressurizing the hydraulic chamber on the side to fall when the fall prevention cylinder is pressurized. In addition, the crane is characterized in that an oil drainage path from the hydraulic chamber of the fall prevention cylinder is sealed. A boom, a jib that can be raised and lowered at the tip of the boom, a holding wire that holds the jib tilted forward so as to cause it to move rearward, and the boom and the jib that spans the jib forward A crane having a fall prevention cylinder for driving,
When the tension of the holding wire decreases and reaches a predetermined allowable tension, the hydraulic chamber serving as the side to be collapsed when pressurizing the fall prevention cylinder is pressurized with a predetermined fall prevention pressure, and then the fall prevention is performed. A crane characterized in that a drainage path from the hydraulic chamber of a cylinder is sealed.   When the hydraulic chamber of the overturn prevention cylinder is pressurized with a predetermined overturn prevention pressure and the tension of the holding wire increases to reach a predetermined stable tension, oil is discharged from the hydraulic chamber of the overturn prevention cylinder. The crane according to claim 2, wherein the path is sealed.   An oil discharge path from the hydraulic chamber of the overturn prevention cylinder is sealed at a predetermined position, and an oil supply path of the overturn prevention cylinder to the hydraulic chamber passes through a circulation circuit of the overturn prevention cylinder. The crane according to any one of claims 1 to 3, wherein the crane is connected to a downstream side of the predetermined position of an oil discharge path from the hydraulic chamber.   The oil drainage path from the hydraulic chamber of the overturn prevention cylinder is sealed when the length of the boom exceeds a predetermined holding length. A crane according to claim 1.

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