JP2019014591A - Work machine - Google Patents

Abstract

To immediately prevent fall of a suspended load if an abnormal state arises in a command signal that controls the capacity of a motor in a work machine including a winch drum driven by a secondary control system.SOLUTION: A crane comprises: a main winding winch; a hydraulic pump 51 of variable capacity type; a hydraulic motor 52 of variable capacity type for both inclinations, which rotates the main winding winch; a first main oil passage 50A; a second main oil passage 50B; a motor capacity control unit 50T; and a communication switching unit 50S. In conjunction with a situation in which a command signal for motor capacity control falls in a specific abnormal state, the motor capacity control unit 50T sets a capacity for the hydraulic motor 52 to an emergency capacity that is greater than zero and at which torque can be generated for the main winding winch in a rotating direction in which a suspended load can be lifted. In a case where the command signal falls in an abnormal state, a communication switching unit 50S blocks circulation of hydraulic oil in each of the first main oil passage 50A and the second main oil passage 50B.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a work machine including a winch that winds and unloads a suspended load.

  Conventionally, a crane equipped with a winch system for lifting and lowering a suspended load is known as a work machine. In such a crane, it is necessary to prevent the suspended load from dropping even when an abnormality such as breakage of the piping of the hydraulic circuit occurs during lifting of the suspended load.

  In the technique disclosed in Patent Document 1, an external pilot type counter balance valve is arranged in a flow path on the meter-out side of a hydraulic motor that drives a winding winch. This counter balance valve operates to throttle the flow path on the meter-out side when the pressure of the hydraulic oil on the meter-in side becomes equal to or lower than a predetermined set pressure. As a result, it is possible to prevent the pressure on the meter-in side from decreasing due to breakage of the piping and the like, and it is possible to hydraulically brake the rotation of the hydraulic motor, thereby preventing the suspended load from falling.

  2. Description of the Related Art In recent years, a secondary control system (hereinafter referred to as SCS) that aims to save energy has been applied as a system for driving work machines such as cranes. The SCS includes a hydraulic variable displacement pump and a hydraulic double tilt variable displacement motor connected to an actuator. While the variable displacement pump maintains the pressure of the main circuit constant, the displacement of the variable displacement motor and the discharge displacement (push displacement) are adjusted, thereby realizing actuator position control, speed control, torque control, and the like. . Patent Document 2 discloses a technique in which such SCS is applied to a swing system of a hydraulic excavator.

JP 2000-310201 A JP-A-9-88905

  By applying the SCS as described above to a winch drive circuit, it is possible to drive the winch without requiring a control valve existing in a conventional circuit. As a result, reduction of valve pressure loss and power regeneration can be realized. The inventor of the present invention has found a new problem when the SCS is applied to a winch system of a work machine. The problem is that it is difficult to immediately stop the falling load if an abnormality occurs in the command signal for controlling the motor capacity during the lifting or lowering operation of the suspended load. Specifically, in a winch system to which SCS is applied, the motor capacity at the time of failure differs depending on the way of motor capacity control failure (control current ground fault, ground fault, etc.). In particular, a meter-in side oil passage and a meter-out side oil corresponding to lowering of a suspended load between a first main oil passage leading to the first port of the motor and a second main oil passage leading to the second port of the motor. The road may turn over. Therefore, with the single counter balance valve as in the technique described in Patent Document 1, it is difficult to stop the falling load depending on the use conditions of the crane. In addition, since the hydraulic motor is a double-tilt variable displacement type, tilt control may stop when the motor capacity is zero during an abnormality. In this case, even if the meter-out flow path of the hydraulic motor is throttled by the counter balance valve as described above, the brake torque is not generated in the hydraulic motor and the winch cannot be stopped. As described above, in the winch system to which the SCS is applied, there is a problem that when an abnormality occurs in the circuit that controls the motor capacity, it is not possible to immediately stop the falling load.

  The present invention has been made in view of the above problems, and in a work machine including a winch drum driven by a secondary control system, when an abnormality occurs in a command signal for controlling the capacity of a variable displacement motor, the suspension is suspended. The purpose is to quickly prevent the fall of the load.

  A work machine according to an aspect of the present invention includes a rope connected to a suspended load, the rope connected to the rope, and rotating in a first rotation direction around an axis to wind up the suspended load. A winch drum that rotates around the axis in a second rotation direction opposite to the first rotation direction and unwinds the suspended load by feeding out the rope; and a variable displacement hydraulic pressure that discharges hydraulic oil A bi-tilt variable displacement hydraulic motor connected to the pump and the winch drum, and accepts hydraulic oil discharged from the hydraulic pump and discharges hydraulic oil, so that the hydraulic motor can be adapted to the capacity of the hydraulic motor. The bi-tilt variable displacement hydraulic motor capable of rotating the winch drum in the first rotation direction and the second rotation direction, and the hydraulic pump and the hydraulic motor communicate with each other. One oil passage, a second oil passage communicating the hydraulic motor and the tank, an operated portion that receives operations for lifting and lowering the suspended load, and an operation amount that the operated portion receives When the command signal output from the output unit and the command signal output from the output unit are in a normal state, the capacity of the hydraulic motor is controlled according to the command signal, and the command signal is a specific signal. In conjunction with an abnormal condition, the capacity of the hydraulic motor is set to an emergency capacity that is larger than zero and capable of generating torque in the first rotation direction with respect to the winch drum. A control unit, and a determination unit that determines the normal state and the abnormal state of the command signal. When the command signal is determined to be the abnormal state, the first oil passage and the second oil passage are provided. That and a blocking mechanism for blocking respectively the circulation of the hydraulic oil.

  According to this configuration, in a work machine including a winch drum driven by a secondary control system, when an abnormality occurs in a command signal for controlling the capacity of a variable displacement hydraulic motor, the capacity of the hydraulic motor is set to an emergency capacity. Is done. The emergency capacity is greater than zero and generates torque in the rotational direction that winds up the suspended load on the winch drum. Further, the blocking mechanism blocks the flow of hydraulic oil in the first oil passage and the second oil passage, respectively. As a result, the hydraulic motor generates torque in the direction of winding up the suspended load while pushing away the hydraulic oil remaining on the motor side of the blocked first oil passage and second oil passage, and eventually the rotation of the hydraulic motor stops. . For this reason, the winch drum can hydraulically hold the suspended load, and the suspended load can be quickly prevented from falling.

  In the above configuration, the hydraulic motor has a movable part that can move so as to change the capacity of the hydraulic motor, and the motor capacity control part is connected to the movable part of the hydraulic motor, A displacement control cylinder that drives the movable part by receiving and discharging hydraulic oil, and an electromagnetic that receives the command signal output from the output unit and switches supply and discharge of hydraulic oil to and from the displacement control cylinder according to the command signal A direction control valve and an emergency switching mechanism for forcibly switching the electromagnetic direction control valve to a switching position for setting the capacity of the hydraulic motor to the emergency capacity in conjunction with the command signal becoming the abnormal state It is desirable to have.

  According to this configuration, when the command signal output from the output unit is in a normal state, the movable portion of the hydraulic motor is driven by the electromagnetic directional control valve controlling the displacement control cylinder. As a result, the capacity of the hydraulic motor is controlled. Further, when the command signal output from the output unit is in an abnormal state, the switching position of the electromagnetic directional control valve is forcibly switched by the emergency switching mechanism, and the capacity of the hydraulic motor can be set to the emergency capacity.

  In the above configuration, the displacement control cylinder is a first displacement control cylinder that is connected to the movable portion of the hydraulic motor and drives the movable portion, and the first displacement control cylinder includes a cylinder body and the cylinder body. A piston that is movable inside and a rod connected to the piston and the movable part, and the piston defines a rod-side hydraulic chamber and a head-side hydraulic chamber in the cylinder body, and the electromagnetic direction The control valve receives the command signal output from the output unit, and switches supply / discharge of hydraulic oil to and from the rod-side hydraulic chamber and the head-side hydraulic chamber of the first displacement control cylinder according to the command signal. A first electromagnetic directional control valve for moving a piston, wherein the first electromagnetic directional control valve has the command signal set to the abnormal state; In conjunction with the ground fault state, the rod side hydraulic chamber and the head side hydraulic chamber can be switched to an emergency communication position that allows the rod side hydraulic chamber and the head side hydraulic chamber to communicate with each other. In conjunction with the ground fault state, the hydraulic motor has a first urging member that urges the piston so that the movable portion moves to a position where the capacity of the hydraulic motor becomes the emergency capacity. desirable. In addition, the first electromagnetic directional control valve moves in the same direction as the direction in which the first urging member urges the piston in conjunction with the command signal becoming a power supply state as the abnormal state. It is further desirable to switch to an emergency supply / discharge position for supplying and discharging hydraulic oil to and from the rod side hydraulic chamber and the head side hydraulic chamber so as to move the piston.

  According to this configuration, when the command signal for controlling the capacity of the hydraulic motor has a ground fault, the driving force for hydraulically moving the piston is lost by switching the first electromagnetic direction control valve to the emergency communication position. . And the movable part connected to the piston moves to the position where the capacity of the hydraulic motor is set to the emergency capacity by the urging force of the first urging member. For this reason, even when the command signal has a ground fault, the capacity of the hydraulic motor is reliably set to the emergency capacity, and the suspended load can be prevented from falling. On the other hand, when the command signal for controlling the capacity of the hydraulic motor has a power fault, the movable part connected to the piston can be hydraulically moved by switching the first electromagnetic direction control valve to the emergency supply / discharge position. it can. The moved movable part sets the capacity of the hydraulic motor to a capacity capable of winding up the suspended load. For this reason, even if the command signal has a power fault, the suspended load can be prevented from falling.

  In the above configuration, the motor capacity control unit is a second capacity control cylinder that is connected to the movable part of the hydraulic motor and drives the movable part, and the second capacity control cylinder includes a cylinder body and the cylinder. A piston movable within the main body, and a rod connected to the piston and the movable part, and the piston defines a rod-side hydraulic chamber and a head-side hydraulic chamber in the cylinder body, and the electromagnetic The direction control valve receives the command signal output from the output unit, and switches supply / discharge of hydraulic oil to / from the rod-side hydraulic chamber and the head-side hydraulic chamber of the second displacement control cylinder according to the command signal. A second electromagnetic directional control valve for moving the piston, wherein the second electromagnetic directional control valve has the command signal in the abnormal state. The rod-side hydraulic chamber and the head-side hydraulic chamber so that the movable portion moves to a position where the capacity of the hydraulic motor becomes the emergency capacity in conjunction with the ground fault state or the power fault state. It is possible to switch to an emergency supply / discharge position that supplies and discharges hydraulic oil to and from the emergency switching mechanism in conjunction with the command signal becoming the ground fault state or the power fault state, You may have a 2nd biasing member which urges | biases the said 2nd electromagnetic direction control valve so that the said 2nd electromagnetic direction control valve may switch to the said emergency supply / discharge position.

  According to this configuration, when the command signal for controlling the capacity of the hydraulic motor has a ground fault or a power fault, the second electromagnetic directional control valve switches to the emergency supply / discharge position, so that the movable part connected to the piston is It can be moved hydraulically. The moved movable part sets the capacity of the hydraulic motor to a capacity capable of winding up the suspended load. For this reason, even when the command signal has a ground fault or a sky fault, the suspended load can be prevented from falling.

  In the above configuration, a characteristic value detection unit that detects an operation characteristic value of the hydraulic motor, and a storage unit that stores and outputs a target value of the operation characteristic value according to an operation amount received by the operated unit. The determination unit determines that the command signal is in the abnormal state by comparing the operation characteristic value detected by the characteristic value detection unit and the target value output by the storage unit. When the determination unit determines that the command signal is in the abnormal state, the blocking mechanism preferably blocks the flow of hydraulic oil in the first oil passage and the second oil passage.

  According to this configuration, it is determined that an abnormality has occurred in the command signal using the fact that the operating characteristic value of the hydraulic motor deviates from the target value corresponding to the operation amount of the operation lever, and based on the determination Thus, the first oil passage and the second oil passage can be blocked.

  In the above configuration, the shut-off mechanism is disposed in the first oil passage, and is switched between a flow position allowing the flow of hydraulic oil in the first oil passage and a shut-off position blocking the flow. A first directional control valve that operates, and is disposed in the second oil passage, and operates to switch between a flow position that allows the flow of hydraulic oil in the second oil passage and a blocking position that blocks the flow. A second directional control valve, and a switching unit that switches the first directional control valve and the second directional control valve to a cutoff position when the determination unit determines that the command signal is in the abnormal state, It may have.

  According to this configuration, it is possible to easily switch between the flow and shut-off of the hydraulic oil in each oil passage by the first direction control valve and the second direction control valve provided in the first oil passage and the second oil passage, respectively. it can.

  According to the present invention, in a work machine including a winch drum driven by a secondary control system, even when an abnormality occurs in a command signal for controlling the capacity of a variable displacement hydraulic motor, the suspended load is quickly prevented. can do.

1 is a side view of a work machine according to a first embodiment of the present invention. 1 is a hydraulic circuit diagram of a winch drive device for a work machine according to a first embodiment of the present invention. It is a block diagram of the control part of the working machine which concerns on 1st Embodiment of this invention. It is a mimetic diagram explaining the flow of hydraulic fluid at the time of load winding and the rotation direction of a hydraulic motor in the winch drive device of the working machine concerning a 1st embodiment of the present invention. It is a mimetic diagram explaining the flow of hydraulic fluid at the time of unloaded hoisting, and the rotation direction of a hydraulic motor in the winch drive device of the working machine concerning a 1st embodiment of the present invention. It is a mimetic diagram explaining the flow of hydraulic fluid at the time of load loading down and the rotation direction of a hydraulic motor in the winch drive device of the working machine concerning a 1st embodiment of the present invention. It is a mimetic diagram explaining the flow of hydraulic fluid at the time of unloading down and the rotation direction of a hydraulic motor in the winch drive device of the working machine concerning a 1st embodiment of the present invention. 5 is a graph group showing the behavior of the winch drive device when an abnormality occurs in a command signal for controlling the capacity of a variable displacement motor in the work machine according to the first embodiment of the present invention. 6 is a graph group showing the behavior of the winch driving device when an abnormality occurs in a command signal for controlling the capacity of the variable displacement motor in another working device compared with the working machine according to the first embodiment of the present invention. . It is a hydraulic circuit diagram of the winch drive device of the working machine which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a crane 10 (work machine) according to a first embodiment of the present invention. Note that FIG. 1 shows directions of “up”, “down”, “front”, and “rear”, but these directions are for convenience in order to describe the structure of the crane 10 according to the present embodiment. It is shown, and does not limit the structure, assembly method, usage mode, or the like of the work machine according to the present invention.

  The crane 10 includes an upper swing body 11 corresponding to the crane body, a lower traveling body 12 that can move the upper swing body 11 and that can move on the ground, a boom 13 that functions as a hoisting member, and a boom hoist. A lattice mast 14 and a box mast 15 which are members for use. The boom 13 is rotatably supported by the upper swing body 11 so as to be able to rise and fall around a horizontal axis. The lattice mast 14 is rotatably supported by the upper swing body 11 around a rotation axis parallel to the rotation axis of the boom 13 at a position on the rear side of the boom 13. The lattice mast 14 serves as a support column for the rotation of the boom 13. The box mast 15 has a base end and a rotation end (tip), and is rotatably connected to the upper swing body 11 on the rear side of the lattice mast 14. The rotation axis of the box mast 15 is arranged in parallel with the rotation axis of the boom 13 and at substantially the same position as the rotation axis of the lattice mast 14.

  The crane 10 further includes a lower spreader 18, an upper spreader 19, a guy line 20, a boom hoisting rope 21, and a boom hoisting winch 22. The guy line 20 connects the upper spreader 19 and the tip of the boom 13. The boom hoisting rope 21 is pulled out from the boom hoisting winch 22 and hung on the first mast sheave 141 and the second mast sheave 142 at the tip of the lattice mast 14, and then the sheave block of the lower spreader 18 and the sheave block of the upper spreader 19. Multiple times between and. The boom hoisting winch 22 changes the distance between the sheave block of the lower spreader 18 and the sheave block of the upper spreader 19 by winding and unwinding the boom hoisting rope 21, and the boom 13 is moved relative to the lattice mast 14. The boom 13 is raised and lowered while rotating relatively.

  Further, the crane 10 includes a guy line 23, a mast hoisting rope 24, and a mast hoisting winch 25. The guy line 23 connects the tip of the lattice mast 14 and the rotating end of the box mast 15. The mast hoisting rope 24 is hung a plurality of times between a sheave block 26 disposed on the upper swing body 11 and a sheave block 27 disposed on a rotating end portion of the box mast 15. The mast hoisting winch 25 winds and unwinds the mast hoisting rope 24 and changes the distance between the sheave block 26 and the sheave block 27. As a result, the lattice mast 14 is raised and lowered while the box mast 15 and the lattice mast 14 rotate integrally with the upper swing body 11.

  The crane 10 is mounted with a main winding winch 30 (winch drum) and an auxiliary winding winch 31 for lifting and lowering a suspended load. The main winding winch 30 performs lifting and lowering of a suspended load by a main winding rope 32 (rope). Specifically, the main winding winch 30 rotates in the first rotation direction around the axis and winds up the main winding rope 32 to wind up the suspended load. The main winding winch 30 rotates around the axis in the second direction opposite to the first rotation direction. The suspended load is lowered by rotating in the rotation direction and feeding out the main winding rope 32. A main hook 34 </ b> A for a suspended load is connected to the main winding rope 32 that is suspended from the tip of the boom 13. When the main winding winch 30 winds or unwinds the main winding rope 32, the main hook 34A connected to the suspended load is wound and unwound. Similarly, the auxiliary winding winch 31 performs lifting and lowering of the suspended load by the auxiliary winding rope 33 to which the auxiliary winding hook 34B is connected. Further, a counterweight 35 for adjusting the balance of the crane 10 is loaded on the rear portion of the upper swing body 11, and a counterweight 36 is further disposed behind the upper swing body 11.

  FIG. 2 is a hydraulic circuit diagram of the hydraulic drive device 50 (winch drive device) of the crane 10 according to the present embodiment. FIG. 3 is an electrical block diagram of the control unit 70 of the crane 10 according to the present embodiment.

  The crane 10 includes a hydraulic drive device 50. The hydraulic drive device 50 is a system that drives the main winding winch 30 and is applied with a secondary control system (hereinafter referred to as SCS). In the present embodiment, the hydraulic drive device 50 is described as driving the main winding winch 30, but the hydraulic driving device 50 may drive the auxiliary winding winch 31. Referring to FIG. 2, a hydraulic drive device 50 includes a hydraulic pump 51, a hydraulic motor 52, a first main oil passage 50A (first oil passage), and a second main oil passage 50B (second oil passage). , An accumulator 53, a communication switching unit 50S (blocking mechanism), a motor capacity control unit 50T, and a relief valve 57.

  The hydraulic pump 51 receives a driving force of an engine (drive source) (not shown), and sucks and discharges hydraulic oil to be supplied to the hydraulic motor 52 from the tank. The hydraulic pump 52 according to the present embodiment is a variable displacement hydraulic pump, and the capacity (displacement volume) of the hydraulic pump 51 is changed by inputting a pump command signal to a regulator (not shown) included in the hydraulic pump 51. As a result, the pump discharge flow rate that is the flow rate of the hydraulic oil discharged from the hydraulic pump 51 changes. The pump command signal is output from the drive control unit 701 (FIG. 3) described later through the output unit 705.

  The hydraulic motor 52 is a double tilt variable displacement type hydraulic motor connected to the main winding winch 30. The hydraulic motor 52 receives the hydraulic oil discharged from the hydraulic pump 51 and discharges the hydraulic oil, thereby rotating the main winding winch 30 about the axis in the first rotation direction and the second rotation direction. In this embodiment, the hydraulic motor 52 is a swash plate type motor, and has a swash plate (not shown) (movable part, variable capacity mechanism) that can move so as to change the capacity of the hydraulic motor 52. The tilt of the swash plate is controlled by the motor capacity control unit 50T. The hydraulic motor 52 has a motor first port 52A and a motor second port 52B.

  The first main oil passage 50 </ b> A communicates the hydraulic pump 51 and the motor first port 52 </ b> A of the hydraulic motor 52.

  The second main oil passage 50B connects the motor second port 52B of the hydraulic motor 52 and the tank.

  The accumulator 53 is connected to a portion between the first directional control valve 55 and the hydraulic motor 52 described later in the first main oil passage 50A. The accumulator 53 accumulates the energy of the hydraulic oil discharged from the motor first port 52A.

  The communication switching unit 50S has a function of switching between the flow of hydraulic oil and the blockage of the flow in the first main oil passage 50A and the second main oil passage 50B. In particular, in the present embodiment, the communication switching unit 50S includes the first main oil passage 50A and the first main oil passage 50A when the command signal input to the motor capacity control unit 50T is in a specific abnormal state (a power fault or a ground fault). 2 Cut off the flow of hydraulic oil in the main oil passage 50B. The communication switching unit 50 </ b> S includes an electromagnetic direction control valve 54 (switching unit), a first direction control valve 55, and a second direction control valve 56. The communication switching unit 50S constitutes a part of the blocking mechanism of the present invention.

  The first directional control valve 55 is a pilot-operated directional control valve, and has one pilot port connected to the first pilot oil passage 50C as shown in FIG. When the pilot pressure is not supplied to the pilot port, the first directional control valve 55 is maintained at the shut-off position in FIG. 2 by the biasing force of the spring member. As a result, the flow of hydraulic oil in the first main oil passage 50A is blocked. On the other hand, the first directional control valve 55 is switched to the communication position (flow position) when the pilot pressure is received by the pilot port through the first pilot oil passage 50C. As a result, the working oil can be circulated in the first main oil passage 50A.

  Similarly, the 2nd direction control valve 56 consists of a pilot operated direction control valve, and has one pilot port connected to 2nd pilot oil path 50D, as shown in FIG. When the pilot pressure is not supplied to the pilot port, the second directional control valve 56 is maintained at the shut-off position in FIG. 2 by the biasing force of the spring member. As a result, the flow of hydraulic oil in the first main oil passage 50A is blocked. On the other hand, the second direction control valve 56 is switched to the communication position (flow position) when the pilot pressure is received in the pilot port through the second pilot oil passage 50D. As a result, the working oil can be circulated in the second main oil passage 50B. In addition, the pressure loss of the hydraulic fluid in the 1st direction control valve 55 and the 2nd direction control valve 56 is smaller than the conventional control valve (flow control valve).

  The electromagnetic direction control valve 54 has one solenoid as shown in FIG. When the solenoid receives a command signal output from the output unit 705 of the control unit 70 described later, the electromagnetic direction control valve 54 is connected to the first main oil passage 50A, the first pilot oil passage 50C, and the second pilot oil passage 50D. Can be switched to the communication position. On the other hand, when the determination unit 703 described later determines that the command signal is in an abnormal state, the command signal output from the output unit 705 is not input to the solenoid. In this case, the electromagnetic direction control valve 54 blocks communication between the first main oil passage 50A, the first pilot oil passage 50C, and the second pilot oil passage 50D. The electromagnetic direction control valve 54 synchronizes and switches the flow and shutoff of hydraulic oil in the first direction control valve 55 and the second direction control valve 56.

  The motor capacity control unit 50T has a function of controlling the capacity (tilt) of the hydraulic motor 52. At this time, when a command signal output from the output unit 705 described later is in a normal state, the motor capacity control unit 50T receives the command signal and controls the capacity of the hydraulic motor 52 according to the command signal. In addition, the motor capacity control unit 50T sets the capacity of the hydraulic motor 52 to the emergency capacity in conjunction with the command signal output from the output unit 705 becoming a specific abnormal state. The emergency capacity is a capacity that is greater than zero and capable of generating torque in the rotational direction (first rotational direction) in which the suspended load is wound around the main winding winch 30.

  Referring to FIG. 2, the motor displacement control unit 50T includes a displacement control cylinder 60 (first displacement control cylinder), an urging spring 64 (emergency switching mechanism, first urging member), and an electromagnetic directional control valve 65. (First electromagnetic directional control valve).

  The capacity control cylinder 60 is connected to a swash plate (movable part) of the hydraulic motor 52 and receives the hydraulic oil and discharges the hydraulic oil to drive the swash plate. The capacity control cylinder 60 has a cylinder body 61, a piston 62, and a piston rod 63. The cylinder body 61 has a cylindrical shape. The piston 62 is supported by the cylinder body 61 so as to be movable in the cylinder body 61. One end of the piston rod 63 is connected to the swash plate of the hydraulic motor 52, and the other end of the piston rod 63 is connected to the piston 62. The piston 62 defines a rod-side oil chamber 61A and a head-side oil chamber 61B in the cylinder body 61, respectively. The rod side oil chamber 61A communicates with the hydraulic pump 51 or the tank through the first sub oil passage 60A. The head side oil chamber 61B is communicated with the hydraulic pump 51 or the tank through the second sub oil passage 60B.

  The biasing spring 64 has a function of forcibly switching the electromagnetic direction control valve 65 to a switching position for setting the capacity of the hydraulic motor 52 to the emergency capacity in conjunction with the command signal becoming abnormal. In the present embodiment, the biasing spring 64 biases the piston 62 so that the swash plate of the hydraulic motor 52 moves to a position where the capacity of the hydraulic motor 52 becomes the above-described emergency capacity.

  The electromagnetic direction control valve 65 is a 4-port flow rate control valve (electromagnetic proportional valve). The electromagnetic direction control valve 65 receives a command signal output from the output unit 705 of the control unit 70, and switches supply / discharge of hydraulic oil to / from the displacement control cylinder 60 according to the command signal. Specifically, the electromagnetic direction control valve 65 moves the piston 62 by switching the supply and discharge of hydraulic oil to and from the rod side oil chamber 61A and the head side oil chamber 61B of the capacity control cylinder 60. The electromagnetic direction control valve 65 includes a spool (not shown) that can move inside. The spool can move between the first switching position 65A, the second switching position 65B, the third switching position 65C, and the fourth switching position 65D (emergency communication position). The amount can also be adjusted.

  When the electromagnetic direction control valve 65 is set to the first switching position 65A in a state where the suspended load is suspended from the main hook 34A, the rod-side oil chamber 61A of the capacity control cylinder 60 passes through the electromagnetic direction control valve 65. While communicating with the hydraulic pump 51, the head side oil chamber 61B communicates with the tank. As a result, the hydraulic oil discharged from the hydraulic pump 51 flows from the first sub oil passage 60A into the rod side oil chamber 61A, and the hydraulic oil in the head side oil chamber 61B is discharged to the tank through the second sub oil passage 60B. Then, the swash plate of the hydraulic motor 52 moves to the forward rotation side, and the main winding winch 30 can rotate in the first rotation direction. That is, the suspended load can be wound up. Further, when the electromagnetic direction control valve 65 is set to the second switching position 65B in a state where the suspended load is suspended from the main hook 34A, the rod side oil chamber 61A and the head side are generated while generating a predetermined pressure loss. The oil chamber 61B communicates. That is, the spool of the electromagnetic direction control valve 65 is disposed at the neutral position. When the electromagnetic direction control valve 65 is set to the third switching position 65C, the rod side oil chamber 61A of the capacity control cylinder 60 communicates with the tank, and the head side oil chamber 61B is hydraulically connected via the electromagnetic direction control valve 65. It communicates with the pump 51. As a result, the hydraulic oil discharged from the hydraulic pump 51 flows from the second sub oil passage 60B into the head side oil chamber 61B, and the hydraulic oil in the rod side oil chamber 61A is discharged to the tank through the first sub oil passage 60A. Then, the swash plate of the hydraulic motor 52 moves to the reverse side, so that the main winding winch 30 can rotate in the second rotation direction. That is, the suspended load can be lowered.

  Further, the electromagnetic directional control valve 65 is linked to the fact that the command signal is in a ground fault state, and a fourth switching position 65D (emergency communication position) for communicating the rod side oil chamber 61A and the head side oil chamber 61B with each other. Switch to. At this time, the biasing spring 64 biases the piston 62 so that the swash plate moves to a position where the capacity of the hydraulic motor 52 becomes the emergency capacity in conjunction with the command signal becoming a ground fault state. To do. In addition, the electromagnetic direction control valve 65 switches to the first switching position 65A (emergency supply / discharge position) in conjunction with the command signal being in a power fault state. In the first switching position 65A, the electromagnetic direction control valve 65 causes the rod-side oil chamber 61A and the head-side oil chamber 61B to move the piston 62 in the same direction as the direction in which the biasing spring 64 biases the piston 62. Supply / discharge hydraulic fluid to At this time, the maximum current flows into the electromagnetic direction control valve 65 and switches to the first switching position 65A (emergency supply / discharge position) against the biasing force of the biasing spring 64.

  Further, the hydraulic drive device 50 includes a control unit 70, an operation lever 71 (operated unit), a display unit 72, and a rotation speed sensor 73 (characteristic value detection unit) (FIG. 3).

  The control unit 70 controls the operation of the crane 10 in an integrated manner. As a control signal transmission / reception destination, the hydraulic pump 51, the operation lever 71, the motor capacity control unit 50T, the display unit 72, the rotation speed sensor 73, and the like are electrically connected. Connected. The control unit 70 is also electrically connected to other units provided in the crane 10.

  The control unit 70 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) that is used as a work area of the CPU, and the CPU executes the control program. As a result, the drive control unit 701, the calculation unit 702, the determination unit 703, the storage unit 704, and the output unit 705 are functionally operated.

  The drive control unit 701 controls the drive of the hydraulic pump 51. The calculation unit 702 calculates characteristic values necessary for the operation of the hydraulic drive device 50. The determination unit 703 compares the angular velocity of the hydraulic motor 52 detected by the rotational speed sensor 73 with the target value of the angular velocity output by the storage unit 704, so that the command signal input to the motor capacity control unit 50T is in a normal state. It is determined whether there is a specific abnormal state. Note that the determination unit 703 constitutes a part of the blocking mechanism of the present invention. The storage unit 704 stores in advance each characteristic value necessary for controlling the hydraulic drive device 50 and can output the characteristic value. The output unit 705 outputs a command signal composed of a control current (current value) corresponding to the operation amount received by the operation lever 71 to the motor capacity control unit 50T during normal operation of the crane 10. Further, the output unit 705 outputs a command signal for blocking the first main oil passage 50A and the second main oil passage 50B to the electromagnetic direction control valve 54 according to the determination result of the determination unit 703.

  The operation lever 71 receives operations for lifting and lowering the suspended load. The operation lever 71 is disposed in the cab (operator's cab) of the crane 10. The operation lever 71 can be switched between a hoisting operation area for instructing hoisting of the suspended load, a lowering operation area for instructing lowering of the suspended load, and a neutral operation position between both operation areas. It is said that.

  The crane 10 further includes a negative brake (not shown). The negative brake has a function of forcibly preventing the rotation of the main winding winch 30. The negative brake mechanically abuts on the rotating shaft or drum surface of the main winding winch 30 to restrict the rotation of the main winding winch 30. In the present embodiment, when the operation lever 71 is disposed at the neutral operation position, the rotation of the main winding winch 30 is restricted by the negative brake.

  The display unit 72 is a liquid crystal monitor arranged in the cab of the crane 10 and displays various status information of the hydraulic drive device 50 in addition to various operation information of the crane 10.

  The rotational speed sensor 73 detects the rotational speed (angular speed) of the hydraulic motor 52. The rotational speed sensor 73 detects the rotational direction (first direction, second direction) of the hydraulic motor 52. The rotational speed of the hydraulic motor 52 detected by the rotational speed sensor 73 corresponds to the operating characteristic value of the hydraulic motor according to the present invention.

  The relief valve 57 (FIG. 2) operates so that the pressure in the first main oil passage 50A does not exceed a predetermined pressure. As a result, in a state where the first directional control valve 55 opens the first main oil passage 50A, the relief valve 57 has a function of keeping the pressure of the first main oil passage 50A constant. Note that a pressure sensor (not shown) is provided in the first main oil passage 50A, and the pressure of the first main oil passage 50A is constant by adjusting the capacity of the hydraulic pump 51 in accordance with the detection result of the pressure sensor. May be kept.

  As described above, in the secondary control system, the first main oil passage 50A extending from the hydraulic pump 51 is always on the high pressure side, and the second main oil passage 50B connected to the tank is always on the low pressure side. Then, the pressure of the hydraulic oil discharged from the hydraulic motor 52 is kept constant, and the capacity (tilt) of the hydraulic motor 52 is adjusted, whereby the main hoist winch 30 lifts and lowers the suspended load. The Therefore, unlike the conventional winch system, a control valve is not required between the hydraulic pump and the hydraulic motor, and the pressure loss of the hydraulic oil is reduced. As a result, an energy saving effect is realized as compared with the prior art.

  4 to 7 are schematic diagrams for explaining the flow of hydraulic oil and the rotation direction of the hydraulic motor 52 in the lifting and lowering operations of the suspended load in the crane 10 to which the secondary control system according to the present embodiment is applied. is there. Normally, the hydraulic motor 52 generates torque (load torque) generated by the load of the suspended load and mechanical loss torque (friction torque) such as friction. 4 to 7, the sum of the load torque and the friction torque is expressed as an external torque. Since the load torque is generated by gravity based on the mass of the suspended load, it always acts as a torque in the lowering rotation direction regardless of the rotation direction of the hydraulic motor 52. On the other hand, since the friction torque is generated in the direction opposite to the rotation direction of the hydraulic motor 52, the acting direction is reversed depending on the rotation direction of the hydraulic motor 52. Therefore, when the suspended load is wound up, the friction torque and the load torque act in the same rotational direction. Therefore, the hydraulic motor 52 needs to output a torque equal to or greater than (absolute value of load torque + absolute value of friction torque). On the other hand, when the suspended load is lowered, the friction torque acts in a direction opposite to the load torque, so that part of the load torque and part of the friction torque cancel each other. For this reason, the torque required for the hydraulic motor 52 is relatively smaller than that during winding.

  FIG. 4 shows a loaded state in which a suspended load is hung on the main hook 34 </ b> A (FIG. 1) connected to the main winding rope 32 and the suspended load is wound up. In this case, when the tilt of the hydraulic motor 52 is set to a predetermined value by the motor capacity control unit 50T, the hydraulic oil flows from the high pressure side to the low pressure side through the first main oil passage 50A and the second main oil passage 50B. . Further, since the motor torque of the hydraulic motor 52 is larger than the external torque (load torque generated in the main winding winch 30 due to the load of the suspended load + friction torque), the hydraulic motor 52 has a load direction of the suspended load (load torque Rotate in the opposite direction (first rotation direction). As a result, the suspended load is wound up.

  FIG. 5 shows a state in which the main hook 34A is wound up in a no-load state in which the main hook 34A (FIG. 1) connected to the main winding rope 32 is not suspended. The hydraulic fluid flows through the first main oil passage 50A and the second main oil passage 50B from the high pressure side to the low pressure side. Also in this case, since the motor torque of the hydraulic motor 52 is larger than the external torque (load torque generated in the main winding winch 30 due to the load of the main hook 34A + friction torque), the hydraulic motor 52 is connected to the main hook 34A. It rotates in the direction opposite to the load direction (direction of load torque) (first rotation direction). As a result, the main hook 34A that is not suspended is wound up.

  FIG. 6 shows a loaded state in which a suspended load is hung on the main hook 34 </ b> A (FIG. 1) connected to the main winding rope 32 and the suspended load is lowered. In this case, when the tilt of the hydraulic motor 52 is set to the reverse rotation side by the motor capacity control unit 50T, the hydraulic oil partially passes through the first main oil passage 50A and the second main oil passage 50B from the low pressure side to the high pressure side. Flowing into. At this time, part of the hydraulic oil is collected by the accumulator 53. In addition, since the motor torque of the hydraulic motor 52 is smaller than the external torque (load torque generated by the load of the suspended load−friction torque), the hydraulic motor 52 has the load direction of the suspended load (the direction of the load torque, the second rotation direction). ). As a result, the suspended load is lowered.

  Further, FIG. 7 shows a state in which the main hook 34A is unloaded in a no-load state in which the main hook 34A (FIG. 1) connected to the main winding rope 32 is not suspended. . In this case, the hydraulic oil flows through the first main oil passage 50A and the second main oil passage 50B from the high pressure side to the low pressure side. Further, since the motor torque of the hydraulic motor 52 is larger than the external torque (load torque-friction torque generated in the main winding winch 30 due to the load of the main hook 34A), the hydraulic motor 52 has a load direction (load torque) of the suspended load. , Second rotational direction, external torque direction and friction torque direction). As a result, the main hook 34A is wound down. In the case of FIG. 7, the friction torque is larger than the load torque, so the direction in which the external torque acts is reversed compared to FIG.

  Thus, in the winch system to which the secondary control system is applied, the meter-in side channel and the meter-out side channel (the direction in which hydraulic oil flows) of the hydraulic motor 52 when the suspended load (main hook 34A) falls (falls). May invert (FIGS. 6 and 7). Further, as shown in FIG. 2, in the oil passage around the hydraulic motor 52 in the hydraulic drive device 50, the first main oil passage 50A connected to the hydraulic pump 51 is always at a high pressure, and the first main oil passage 50A connected to the tank. 2 The main oil passage 50B is always maintained at a low pressure. Further, the capacity of the hydraulic motor 52 at the time of the failure differs depending on the way of failure in the capacity control mechanism of the hydraulic motor 52 (control current power supply fault, ground fault, etc.). Therefore, even if an external pilot type counter balance valve is arranged in one of the first main oil passage 50A and the second main oil passage 50B as in the prior art, depending on the use conditions of the crane 10, the hydraulic motor When control of 52 becomes impossible, the fall of a suspended load cannot be prevented. Furthermore, since the hydraulic motor 52 is a double tilt variable displacement type, the capacity of the hydraulic motor 52 may become zero when a failure occurs. In this case, even if the meter-out flow path of the hydraulic motor 52 is throttled by a mechanism such as a conventional counter balance valve, no torque (brake torque) is generated in the hydraulic motor 52, resulting in the main winding. The winch 30 cannot be stopped. Thus, since the winch system to which the secondary control system is applied has characteristics different from those of the conventional winch system, it is necessary to take measures to prevent the suspended load from dropping at the time of failure.

  In order to solve the above problems, in the present embodiment, the motor capacity control unit 50T and the communication switching unit 50S execute emergency control. Referring to FIG. 2, when a capacity control command signal (current value) output from output unit 705 (FIG. 3) and input to electromagnetic directional control valve 65 becomes zero due to an abnormality (ground fault) ), The electromagnetic direction control valve 65 is returned to the fourth switching position 65D (initial position) in FIG. 2 by the biasing spring 65E. At the fourth switching position 65D, the rod side oil chamber 61A and the head side oil chamber 61B of the capacity control cylinder 60 are both communicated with the tank. For this reason, the pressures in the rod side oil chamber 61A and the head side oil chamber 61B are equal (same pressure). At this time, the piston rod 63 moves the swash plate of the hydraulic motor 52 to the emergency position on the normal rotation side by the biasing force of the biasing spring 64. When the swash plate is moved to the emergency position, the displacement (displacement volume) of the hydraulic motor 52 is greater than zero, and torque is applied in the direction of lifting the suspended load with respect to the main winding winch 30 (first rotation direction). It becomes an emergency capacity to generate. These operations are mechanically performed in conjunction with the ground fault of the current value of the command signal.

  On the other hand, the rotation speed sensor 73 (FIG. 3) detects the rotation speed (angular speed) of the hydraulic motor 52 when the operation lever 71 is operated. The storage unit 704 outputs a target value of the angular velocity of the hydraulic motor 52 according to the operation amount received by the operation lever 71. Then, the determination unit 703 compares the angular velocity of the hydraulic motor 52 detected by the rotation speed sensor 73 with the target value of the angular velocity output by the storage unit 704, and if the difference between the two exceeds a predetermined threshold, It is determined that the command signal has entered a specific abnormal state. When the capacity of the hydraulic motor 52 is set to the above-described emergency capacity, the emergency capacity is greatly different from the capacity corresponding to the operation amount of the operation lever 71, and thus it is determined as an abnormal state as described above. As a result, the output unit 705 outputs an emergency command signal to the electromagnetic direction control valve 54, and the electromagnetic direction control valve 54 is set to the communication position. When pilot pressure is supplied to the pilot ports of the first directional control valve 55 and the second directional control valve 56 through the first pilot oil passage 50C and the second pilot oil passage 50D, the first directional control valve 55 and the second directional control valve 55 The two-way control valve 56 is switched to the cutoff position. As a result, the first main oil passage 50A and the second main oil passage 50B are blocked.

  Thus, when the current value of the command signal input to the electromagnetic direction control valve 65 of the motor capacity control unit 50T is grounded, the capacity of the hydraulic motor 52 is set to an emergency capacity that is not zero, and the first main The flow of hydraulic oil in the oil passage 50A and the second main oil passage 50B is blocked. As a result, the hydraulic motor 52 generates torque in the rotational direction in which the suspended load is wound up while pushing away the hydraulic oil remaining on the hydraulic motor 52 side of the blocked first main oil passage 50A and second main oil passage 50B. The brake torque is applied to the hydraulic motor 52, and the rotation of the hydraulic motor 52 stops. For this reason, the main winding winch 30 can hydraulically hold the suspended load, and can prevent the suspended load from falling quickly.

  On the other hand, when the command signal input to the electromagnetic direction control valve 65 of the motor capacity control unit 50T goes into a power fault (the signal remains swinging to the maximum value), the electromagnetic direction control valve 65 is forcibly changed to the first in FIG. The switching position 65A is set. At the first switching position 65A, the capacity of the hydraulic motor 52 is increased to a capacity that generates torque in the direction of lifting the suspended load with respect to the main winding winch 30. That is, the capacity of the hydraulic motor 52 is set to an emergency capacity that is not zero. Moreover, since the said emergency capacity | capacitance differs greatly from the capacity | capacitance according to the operation amount of the operation lever 71, the determination part 703 determines with an instruction | command signal being an abnormal state as mentioned above. As a result, the flow of hydraulic oil in the first main oil passage 50A and the second main oil passage 50B is similarly blocked. Therefore, as in the case of the ground fault, the brake torque is applied to the hydraulic motor 52, and the suspended load can be quickly prevented from falling.

  FIG. 8 is a group of graphs showing the behavior of the hydraulic drive device 50 when an abnormality occurs in the command signal for controlling the capacity of the hydraulic motor 52 in the crane 10 according to the present embodiment at the time of the load-lowering operation. FIG. 9 is a hydraulic drive in the case where an abnormality occurs in the command signal for controlling the capacity of the variable displacement motor during the load-lowering operation in another working device compared with the crane 10 according to the present embodiment. It is a graph group which shows the behavior of an apparatus.

  Referring to FIG. 8, the operation lever 71 is operated by the operator from time 0, and the suspended load is lowered. In the present embodiment, when a failure occurs in the command signal at time T1 and the current of the command signal is grounded, the capacity of the hydraulic motor 52 is quickly set to the emergency capacity as described above (FIG. 8). (See “At Failure (Control Case)” in the graph of motor capacity). After this, at time T2, the first directional control valve 55 and the second directional control valve 56 shut off the first main oil passage 50A and the second main oil passage 50B (see the directional control valve graph of FIG. 8). ). Since the operator is not aware of the failure of the command signal, the operator continues to operate the operation lever 71 (see the lever graph in FIG. 8). The first main oil passage 50A and the second main oil passage 50B are shut off and the capacity of the hydraulic motor 52 is set to the emergency capacity, so that the brake torque is applied to the hydraulic motor 52 and the motor speed is hydraulically reduced. Eventually, it becomes zero (see the motor speed graph in FIG. 8). Eventually, the operator notices the deceleration of the hydraulic motor 52 and the stoppage of the main winding winch 30, or starts returning the operation lever 71 to the operation neutral region at time T3 according to the normal work procedure. When the operation lever 71 reaches the operation neutral region at time T4, a negative brake (not shown) is turned on, and the rotation of the main winding winch 30 is mechanically blocked. Thus, in the present embodiment, the hydraulic motor 52 can be braked hydraulically before the operator returns the operation lever 71 to the operation neutral region. Therefore, even when a failure of the command signal occurs, it is possible to quickly prevent the suspended load from dropping. In FIG. 8, for comparison, there are also graphs when the motor capacity control command signal remains abnormal (non-control case) and when the motor capacity control command signal is normal (normal). Show.

  On the other hand, with reference to FIG. 9, the behavior at the time of unloading with a load in the hydraulic drive apparatus that does not include the hanging load fall prevention mechanism according to the present embodiment will be described. At time t1, a failure occurs in the command signal, and the current of the command signal is grounded. The operator starts returning the operation lever 71 to the operation neutral region at time t2 without noticing the failure of the command signal. When no failure has occurred in the command signal, the capacity of the hydraulic motor is increased by this operation, so that the rotation of the hydraulic motor is decelerated (see the broken lines in the motor capacity and motor speed graphs in FIG. 9). However, when a failure occurs in the command signal, the motor capacity is not increased. Therefore, at time t3 when the operation lever reaches the operation neutral region completely, the main winch 30 is rotated by the mechanical negative brake. Stop. That is, the suspended load is dropped by an amount corresponding to the area (integrated value) of the triangle surrounded by the solid line at the time of failure and the broken line at the normal time from time t2 to time t3.

  As described above, in the present embodiment, when an abnormality occurs in the command signal that controls the displacement of the bi-tilt variable displacement hydraulic motor in the work machine including the winch drum driven by the secondary control system, the hydraulic motor The capacity is set to the emergency capacity. The emergency capacity is greater than zero and generates torque in the rotational direction that winds up the suspended load on the winch drum. Further, the blocking mechanism blocks the flow of hydraulic oil in the first oil passage and the second oil passage, respectively. As a result, the hydraulic motor generates torque in the rotational direction in which the suspended load is wound up while pushing away the hydraulic oil remaining in the blocked first oil passage and second oil passage, and eventually the rotation of the hydraulic motor stops. For this reason, the winch drum can hydraulically hold the suspended load, and the suspended load can be quickly prevented from falling.

  As described above, when the secondary control system is applied to the winch system, the rotation direction of the hydraulic motor 52 before an emergency stop such as a failure is different depending on the mass of the suspended load and the type of the failure (for example, the difference between a power fault and a ground fault). . In particular, in a scene where a suspended load may be dropped due to a failure, the hydraulic motor 52 rotates in the lowering direction at the time of the failure. In this embodiment, the hydraulic motor 52 has an emergency capacity and the two oil passages are shut off, so that torque is generated in the rotational direction for winding up the suspended load, and the rotational speed of the hydraulic motor 52 is lowered and finally. Stop.

  In the present embodiment, it is determined that an abnormality has occurred in the command signal by utilizing the fact that the operating characteristic value of the hydraulic motor deviates from the target value corresponding to the operation amount of the operation lever, and the first oil The passage and the second oil passage can be blocked.

  Further, in the present embodiment, the flow and shut-off of the hydraulic oil in each oil passage are easily switched by the first direction control valve and the second direction control valve provided in the first oil passage and the second oil passage, respectively. Can do.

  In this embodiment, when the command signal for controlling the capacity of the hydraulic motor is grounded, the first electromagnetic directional control valve is switched to the emergency communication position, so that the driving force for hydraulically moving the piston is lost. Is called. The movable portion connected to the piston moves to a position where the capacity of the hydraulic motor is set to the emergency capacity by the urging force of the urging member. For this reason, even when the command signal has a ground fault, the capacity of the hydraulic motor can be reliably set to the emergency capacity. In addition, when the command signal for controlling the capacity of the hydraulic motor has a power fault, the movable part connected to the piston can be hydraulically moved by switching the first electromagnetic direction control valve to the emergency supply / discharge position. it can. The moved movable part sets the capacity of the hydraulic motor to a capacity capable of winding up the suspended load. For this reason, even if the command signal has a power fault, the suspended load can be prevented from falling.

  Next, a second embodiment of the present invention will be described. In addition, in this embodiment, since it differs in the structure of a motor capacity | capacitance control part compared with previous embodiment, it demonstrates centering on the said difference and description of a common point is abbreviate | omitted. FIG. 10 is a hydraulic circuit diagram of the crane hydraulic drive device 80 (winch drive device) according to the present embodiment.

  The hydraulic drive device 80 includes a motor capacity control unit 80T instead of the motor capacity control unit 50T of the hydraulic drive device 50 according to the previous embodiment. The motor capacity control unit 80T includes a capacity control cylinder 90 (second capacity control cylinder) and an electromagnetic direction control valve 95 (second electromagnetic direction control valve).

  The capacity control cylinder 90 is connected to the swash plate (movable part) of the hydraulic motor 52 and drives the swash plate. The capacity control cylinder 90 includes a cylinder main body 91, a piston 92, and a piston rod 93. The cylinder body 91 has a cylindrical shape. The piston 92 is supported by the cylinder body 91 so as to be movable in the cylinder body 91. One end of the piston rod 93 is connected to the swash plate of the hydraulic motor 52, and the other end of the piston rod 93 is connected to the piston 92. The piston 92 defines a rod-side oil chamber 91A and a head-side oil chamber 91B in the cylinder body 91, respectively. The rod side oil chamber 91A communicates with the hydraulic pump 51 or the tank through the first sub oil passage 90A. The head side oil chamber 91B communicates with the hydraulic pump 51 or the tank through the second sub oil passage 90B.

  The electromagnetic direction control valve 95 is a three-port flow rate control valve (electromagnetic proportional valve). The electromagnetic direction control valve 95 is electrically connected to the control unit 70 through the control signal circuit 80TA. The electromagnetic direction control valve 95 receives a command signal output from the output unit 705 of the control unit 70, and supplies and discharges hydraulic oil to and from the rod-side oil chamber 91A and the head-side oil chamber 91B of the capacity control cylinder 90 according to the command signal. Is switched to move the piston 92. The electromagnetic direction control valve 95 includes a spool (not shown) that can move inside. The spool can move between the first switching position 95A (emergency supply / discharge position), the second switching position 95B, and the third switching position 95C, and the amount of movement thereof can also be adjusted. .

  When the electromagnetic direction control valve 95 is set to the first switching position 95A, the rod side oil chamber 91A of the displacement control cylinder 90 communicates with the hydraulic pump 51 through the first sub oil passage 90A, and the head side oil chamber 91B is The tank communicates with the two sub oil passages 90B. At this time, the swash plate of the hydraulic motor 52 connected to the piston rod 93 is arranged on the forward rotation side. When the electromagnetic direction control valve 95 is set to the second switching position 95B, the rod-side oil chamber 91A and the head-side oil chamber 91B communicate with each other while generating a predetermined pressure loss. That is, the spool of the electromagnetic direction control valve 95 is disposed at the neutral position, and the swash plate of the hydraulic motor 52 is disposed at the zero tilt position. When the electromagnetic direction control valve 95 is set to the third switching position 95C, the rod side oil chamber 91A of the capacity control cylinder 90 communicates with the tank, and the head side oil chamber 91B is hydraulically connected via the electromagnetic direction control valve 95. It communicates with the pump 91. At this time, the swash plate of the hydraulic motor 52 connected to the piston rod 93 is disposed on the reverse side.

  In this embodiment, even when the command signal for the electromagnetic directional control valve 95 is in an abnormal state of either a power fault or a ground fault, the electromagnetic directional control valve 95 performs the first switching in conjunction with the abnormality of the command signal. Switch to position 95A. In the first switching position 95A, the electromagnetic direction control valve 95 causes the hydraulic oil to flow to the rod-side oil chamber 91A and the head-side oil chamber 91B so that the swash plate moves to a position where the capacity of the hydraulic motor 52 becomes the emergency capacity. Supply and discharge. At this time, the urging spring 95D (emergency switching mechanism, second urging member) moves the electromagnetic directional control valve 95 to the first switching position in conjunction with the command signal becoming a ground fault state or a power fault state. A spool (not shown) of the electromagnetic direction control valve 95 is urged so as to switch to 95A.

  Even in such a configuration, when the command signal for controlling the capacity of the hydraulic motor 52 has a ground fault or a power fault, the electromagnetic directional control valve 95 is connected to the piston rod 93 by switching to the emergency supply / discharge position. The swash plate of the hydraulic motor 52 can be moved hydraulically. The moved swash plate sets the capacity of the hydraulic motor 52 to an emergency capacity capable of winding up the suspended load. For this reason, even when the command signal has a ground fault or a sky fault, the suspended load can be prevented from falling.

  The work machine (crane 10) according to each embodiment of the present invention has been described above. The present invention is not limited to these forms. The following modified embodiments are possible as the working machine according to the present invention.

  (1) In the above embodiment, the crane 10 is used as the work machine, but the present invention is not limited to this. The work machine according to the present invention may include other aspects. Further, the hydraulic motor 52 is not limited to the both-tilt variable displacement type hydraulic motor provided with the swash plate, and may be other both-tilt variable displacement type hydraulic motors such as a tilt shaft type. .

  (2) Further, in each of the above embodiments, the hydraulic drive device 50 (FIG. 2) and the hydraulic drive device 80 (FIG. 10) have been described as having the accumulator 53, but an embodiment without the accumulator 53 may be used. . In this case, the pressure in the first main oil passage 50 </ b> A may be kept constant by the relief valve 57.

  (3) In each of the above embodiments, the rotation speed sensor 73 detects the rotation speed (angular speed) of the hydraulic motor 52 as the characteristic value detection unit that detects the operation characteristic value of the hydraulic motor. However, the present invention is not limited to this. The characteristic value detection unit may detect a rotation angle, a capacity, and the like of the hydraulic motor 52. In this case, it is desirable that the target value corresponding to each characteristic value is stored in the storage unit 704 in accordance with the operation amount of the operation lever 71. Moreover, the aspect by which the abnormal state of a command signal is determined by combining several characteristic values may be sufficient.

  (4) In each of the above embodiments, the motor capacity control unit of the present invention has been described in the aspect including the capacity control cylinder 60 (90) and the electromagnetic direction control valve 65 (95). It is not limited. The control signal circuit 50TA (80TA) to which the command signal is transmitted is provided with an ammeter (not shown), and the normal state and abnormal state (ground fault, power fault) of the command signal are detected according to the detection result of the ammeter. May be. Also in this case, the port position of the electromagnetic directional control valve 65 (95) is switched in the same manner as described above according to the state of the command signal. In addition to the electromagnetic directional control valve 65 (95), another emergency control valve may be added, and the supply and discharge of hydraulic fluid to the capacity control cylinder 60 (90) in an emergency may be controlled by the control valve. .

10 Crane 11 Upper Revolving Body 12 Lower Traveling Body 30 Main Winding Winch (Winch Drum)
32 Main rope (rope)
50 Hydraulic drive unit 50A First main oil passage (first oil passage)
50B Second main oil passage (second oil passage)
50C 1st pilot oil passage 50D 2nd pilot oil passage 50S Communication switching part (blocking mechanism)
50T Motor capacity control unit 50TA Control signal circuit 51 Hydraulic pump 52 Hydraulic motor 52A Motor first port 52B Motor second port 53 Accumulator 54 Electromagnetic direction control valve (switching unit)
55 1st direction control valve 56 2nd direction control valve 57 Relief valve 60 Capacity control cylinder (1st capacity control cylinder)
60A First sub oil passage 60B Second sub oil passage 61 Cylinder body 61A Rod side oil chamber 61B Head side oil chamber 62 Piston 63 Piston rod 64 Biasing spring (emergency switching mechanism, first biasing member)
65 Electromagnetic direction control valve (first electromagnetic direction control valve)
65A 1st switching position 65B 2nd switching position 65C 3rd switching position 65D 4th switching position 65E Biasing spring 70 Control part 701 Drive control part 702 Calculation part 703 Determination part (shut-off mechanism)
704 Storage unit 705 Output unit 71 Operation lever (operated unit)
72 Display Unit 73 Rotational Speed Sensor (Characteristic Value Detection Unit)

Claims (7)

A rope connected to the suspended load;
It is connected to the rope, rotates around the axis in the first rotation direction, winds up the rope, winds up the suspended load, and rotates around the axis in the second rotation direction opposite to the first rotation direction. A winch drum that unwinds the suspended load by paying out the rope;
A variable displacement hydraulic pump that discharges hydraulic oil;
A bi-tilt variable displacement type hydraulic motor connected to the winch drum, which receives hydraulic oil discharged from the hydraulic pump and discharges hydraulic oil, so that the winch is adapted according to the capacity of the hydraulic motor. A both-tilt variable displacement hydraulic motor capable of rotating a drum in the first rotation direction and the second rotation direction;
A first oil passage communicating the hydraulic pump and the hydraulic motor;
A second oil passage communicating the hydraulic motor and the tank;
An operated part that receives operations for hoisting and lowering the suspended load;
An output unit that outputs a command signal having a current value corresponding to an operation amount received by the operated unit;
When the command signal output from the output unit is in a normal state, the hydraulic motor is controlled in accordance with the command signal, and the hydraulic motor is linked with the command signal being in a specific abnormal state. A motor capacity controller that sets the capacity of the emergency capacity to be larger than zero and capable of generating torque in the first rotation direction with respect to the winch drum;
A determination unit that determines the normal state and the abnormal state of the command signal; and when the command signal is determined to be the abnormal state, the flow of hydraulic oil in the first oil passage and the second oil passage A blocking mechanism for blocking each;
A work machine comprising: The hydraulic motor has a movable part movable so as to change the capacity of the hydraulic motor,
The motor capacity controller is
A displacement control cylinder connected to the movable part of the hydraulic motor and receiving the hydraulic oil and driving the movable part by discharging the hydraulic oil;
An electromagnetic directional control valve that accepts the command signal output by the output unit and switches supply and discharge of hydraulic fluid to and from the displacement control cylinder according to the command signal;
In conjunction with the command signal becoming the abnormal state, an emergency switching mechanism for forcibly switching the electromagnetic directional control valve to a switching position for setting the capacity of the hydraulic motor to the emergency capacity;
The work machine according to claim 1, comprising: The displacement control cylinder is a first displacement control cylinder that is connected to the movable portion of the hydraulic motor and drives the movable portion, and the first displacement control cylinder is movable within the cylinder body and the cylinder body. A piston and a rod connected to the piston and the movable part, and the piston defines a rod-side hydraulic chamber and a head-side hydraulic chamber in the cylinder body,
The electromagnetic direction control valve receives the command signal output from the output unit, and switches supply / discharge of hydraulic oil to / from the rod-side hydraulic chamber and the head-side hydraulic chamber of the first displacement control cylinder according to the command signal. A first electromagnetic directional control valve for moving the piston, wherein the first electromagnetic directional control valve is connected to the rod side hydraulic pressure in conjunction with the command signal becoming a ground fault state as the abnormal state. It is possible to switch to an emergency communication position that allows the chamber and the head side hydraulic chamber to communicate with each other,
The emergency switching mechanism biases the piston so that the movable part moves to a position where the capacity of the hydraulic motor becomes the emergency capacity in conjunction with the command signal becoming the ground fault state. The work machine according to claim 2, further comprising a first urging member.   The first electromagnetic directional control valve moves the piston in the same direction as the direction in which the first urging member urges the piston in conjunction with the command signal becoming a power supply state as the abnormal state. The work machine according to claim 3, wherein the working machine is switched to an emergency supply / discharge position for supplying and discharging hydraulic oil to and from the rod side hydraulic chamber and the head side hydraulic chamber so as to be moved. The motor capacity control unit is a second capacity control cylinder that is connected to the movable part of the hydraulic motor and drives the movable part, and the second capacity control cylinder is movable within the cylinder body and the cylinder body. A piston connected to the piston and the movable part, and a rod-side hydraulic chamber and a head-side hydraulic chamber are defined in the cylinder body by the piston,
The electromagnetic direction control valve receives the command signal output from the output unit, and switches supply / discharge of hydraulic oil to / from the rod-side hydraulic chamber and the head-side hydraulic chamber of the second displacement control cylinder according to the command signal. A second electromagnetic directional control valve for moving the piston, and the second electromagnetic directional control valve is interlocked with the command signal becoming a ground fault state or a power fault state as the abnormal state, It switches to an emergency supply / discharge position for supplying and discharging hydraulic oil to and from the rod side hydraulic chamber and the head side hydraulic chamber so that the movable part moves to a position where the capacity of the hydraulic motor becomes the emergency capacity. Is possible and
The emergency switching mechanism is configured so that the second electromagnetic directional control valve switches to the emergency supply / discharge position in conjunction with the command signal becoming the ground fault state or the power fault state. The work machine according to claim 2, further comprising a second biasing member that biases the electromagnetic direction control valve. A characteristic value detector for detecting an operating characteristic value of the hydraulic motor;
A storage unit that stores and outputs a target value of the operation characteristic value according to an operation amount received by the operated unit;
Further comprising
The determination unit determines that the command signal is in the abnormal state by comparing the operation characteristic value detected by the characteristic value detection unit and the target value output by the storage unit,
6. The shut-off mechanism shuts off the flow of hydraulic oil in the first oil passage and the second oil passage, respectively, when the determination unit determines that the command signal is in the abnormal state. The work machine according to any one of the above. The blocking mechanism is
A first directional control valve that is disposed in the first oil passage and that operates to switch between a flow position that allows the flow of hydraulic oil in the first oil passage and a blocking position that blocks the flow;
A second directional control valve disposed in the second oil passage and operable to switch between a flow position allowing the flow of hydraulic oil in the second oil passage and a blocking position blocking the flow;
When the determination unit determines that the command signal is in the abnormal state, a switching unit that switches the first direction control valve and the second direction control valve to a cutoff position, respectively.
The work machine according to claim 6, comprising:

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