JP2001048483A - Safety device for hydraulic winch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly stop a drum when a pipe connecting each hydraulic motor is broken, in a hydraulic winch driven by a pair of hydraulic motors. SOLUTION: This winch is provided with first and second counter balance valves 5, 6 and first and second selecting valves 21, 22, corresponding to first and second hydraulic motors 2, 3 respectively, and the first selecting valve 21 and the second selecting valve 22 are connected with a pipe 23. The first and second selecting valves 21, 22 are severally selected on the base of pressure in the pipe 23, and when the pipe 23 is broken, each of the first and second selecting valves 21, 22 is shifted to a position (a). Therefore, pressure oil in holding conduits 11, 12 is led to spring side pilot chambers 17a, 18a of spools 17, 18 of counter balance valves 5, 6, and then the spools 17, 18 are closed to stop the rotation of the hydraulic motors 2, 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a hydraulic winch in which one winch drum is driven by driving torques of two hydraulic motors.

[0002]

2. Description of the Related Art In a hydraulic winch, when a necessary hoisting torque increases, a hydraulic motor having a large capacity is required. Here, when a large-capacity hydraulic motor is not commercially available, two hydraulic motors are provided for one winch drum. In this case, it is necessary to drive the two hydraulic motors in synchronism with each other.
No. 830. In the device described in this publication, a counterbalance valve is provided in each of the drive circuits of the two hydraulic motors, and one of the counterbalance valves is opened and closed by the pressure of the lowering oil inflow passage of the corresponding hydraulic motor, and The load pressure acting on the hydraulic motor is led to the other counterbalance valve via a pipe, and the other counterbalance valve is opened and closed by the difference in the load pressure acting on each hydraulic motor.

[0003] In such a hydraulic circuit, if the pipe for guiding the load pressure acting on the hydraulic motor to the counterbalance valve is broken, the closing operation of the counterbalance valve may be hindered. Therefore, in the apparatus described in the above publication, a switching valve that uses the pressure in the pipe as a pilot pressure and a negative brake that acts on the winch drum are provided, and the negative brake is operated on the winch drum by switching the switching valve when the pipe is damaged. To prevent the suspended load from falling.

[0004]

The negative brake in the device described in the above publication is a band type brake. Since the band-type brake involves wear of the brake band during use, a troublesome operation of adjusting the braking force is routinely required. In this case, if the braking force is incorrectly adjusted, it becomes impossible to obtain a proper braking force.

An object of the present invention is to provide a safety device for a hydraulic winch which does not require maintenance such as adjustment of a braking force and can reliably stop a drum in case of trouble such as breakage of piping. .

[0006]

Means for Solving the Problems (1) Referring to FIGS. 1 and 2 showing an embodiment, the invention of claim 1 is characterized in that the first and second pumps driven by hydraulic oil from a hydraulic pump 1 are provided. Second hydraulic motors 2 and 3; a winch drum 58 driven up and down by drive torque from the first and second hydraulic motors 2 and 3; A first holding pipeline 11 is formed in the drive circuit of the first embodiment, and the pressure of the first holding pipeline 11 is maintained at a predetermined pressure by opening and closing operation to limit the rotation of the first hydraulic motor 2 in the lowering direction. The second holding pipe 12 is formed in the counterbalance valve 5 and the drive circuit on the outflow side of the second hydraulic motor 3 in the lowering direction, and the pressure of the second holding pipe 12 is set to the first by opening and closing operation. Of the second hydraulic motor 3 so as to be substantially equal to the pressure of the holding line 11 of the second hydraulic motor 3. The second to restrict the rotation in the lowering direction
The present invention is applied to a safety device of a hydraulic winch provided with a counterbalance valve 6 of FIG. 1 and a pipe 23 for guiding the pressure of the first holding pipeline 11 to the second counterbalance valve 6. And it is provided between the 1st holding pipeline 11 and piping 23,
The pressure is switched by the pressure drop in the pipe 23 to shut off the first holding pipe line 11 and the pipe 23 and to release the pressure oil for closing the first counterbalance valve 5 to the first state.
The first switching valve 21, which is sent to the counter balance valve 5,
26, and is provided between the second holding pipe line 12 and the pipe 23, and is switched by the pressure drop in the pipe 23, and the second
The second switching valve 2 that shuts off the holding pipeline 12 and the pipe 23 and sends out pressure oil for closing the second counterbalance valve 6 to the second counterbalance valve 6.
The above-mentioned object is achieved by providing 2,27. (2) According to the invention of claim 2, the first counter balance valve 5 is guided by switching of the first switching valves 21 and 26.
Is closed by the pressure of the holding line 11, and the second counterbalance valve 6 is closed by the pressure of the second holding line 12, which is guided by switching of the second switching valves 22 and 26. . (3) As shown in FIGS. 3 and 4, the first and second inventions are driven by pressure oil from a hydraulic pump 1.
Hydraulic motors 2, 3; a winch drum 58 driven up and down by the drive torque from the first and second hydraulic motors 2 and 3; and a drive on the outflow side of the first hydraulic motor 2 in the lowering direction. A first holding conduit 11 is formed in the circuit, and a pressure of the first holding conduit 11 is maintained at a predetermined pressure by opening / closing operation to limit the rotation of the first hydraulic motor 2 in the lowering direction.
A second holding pipe line 12 is formed in the counterbalance valve 5 and the drive circuit on the outflow side of the second hydraulic motor 3 in the lowering direction,
A second counter that controls the pressure of the second holding pipe 12 to be substantially equal to the pressure of the first holding pipe 11 by opening and closing operation to limit the rotation of the second hydraulic motor 3 in the lowering direction. The present invention is applied to a hydraulic winch safety device including a balance valve 6 and a pipe 23 for guiding the pressure of the first holding pipe line 11 to the second counterbalance valve 6. The first holding pipe 11 is provided between the first holding pipe 11 and the pipe 23, and is switched by the pressure drop in the pipe 23.
First switching valves 28 and 29 for shutting off the air and the pipe 23,
A second counter balance valve is provided between the second holding pipe line 12 and the pipe 23, and is switched by the pressure drop in the pipe 23 to shut off the second holding pipe line 12 and the pipe 23. The above-described object is achieved by providing a second switching valve 27 that sends out pressure oil for closing the valve 6 to the second counterbalance valve 6. (4) As shown in FIG. 4, the invention according to claim 4 is a brake drum 58c that rotates integrally with the winch drum 58.
And a braking device 30 that is operated by pressure oil sent out due to a pressure drop in the pipe 23 and that brakes the rotation of the brake drum 58c by switching the first switching valve 17.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 5 is a side view of a hydraulic crane to which the present invention is applied. As shown in FIG. 5, the crane includes a traveling body 51, a revolving body 53 rotatably mounted on the traveling body 51 via a revolving device 52, and a boom 54 rotatably supported by the revolving body 53. And The upper end of the boom 54 is supported by an up-and-down rope 56a via a pendant rope 55. The boom 54 is raised and lowered by the up-and-down drum 56 feeding or winding up the up-and-down rope 56a. The hook 57 is suspended from the tip of the boom 54 via a hoisting rope 58 a, and the hoisting drum 58 a
The hook 57 is raised and lowered by feeding or winding.

FIG. 1 is a hydraulic circuit diagram showing a configuration of a safety device for a hydraulic winch according to a first embodiment of the present invention. As shown in FIG. 1, the hydraulic winch device includes a variable displacement hydraulic pump 1 and first and second hydraulic motors 2 and 3 driven by hydraulic oil discharged from the hydraulic pump 1.
A directional control valve 4 for controlling the flow of pressure oil supplied from the hydraulic pump 1 to the hydraulic motors 2 and 3;
A winch drum 58 driven up and down by a driving torque from the motor, first and second counterbalance valves 5 and 6 for restricting rotation of the first and second hydraulic motors 2 and 3 in the lowering direction, respectively. An operating lever 7 for inputting a hoisting / unwinding command of the winch drum 58 by an operator, pilot valves 8A and 8B operated by the operating lever 7, and a pilot hydraulic source 9 for supplying pilot pressure oil to the pilot valves 8A and 8B. A valve device 20 for controlling the operation of the counter balance valves 5 and 6. Each hydraulic motor 2,3
Have the same capacity.

The output shafts 2a and 3a of the hydraulic motors 2 and 3 are mechanically connected to the drive shaft 58b of the winch drum 58 by gear trains, and the hydraulic motors 2 and 3 are tuned and driven as described later. The first and second counterbalance valves 5 and 6 have check valves 15 and 16 for blocking the flow in the downward direction, and spools 17 and 18 for allowing the downward flow in accordance with the pilot pressure. The pilot chambers 17a, 17b, 1 are respectively provided on the spring side (closed side) and the opposite side (open side) of the spools 17, 18 respectively.
8a and 18b are provided. An overload relief valve 1 for relieving the counterbalance valves 5 and 6 and the pressures (holding pressures) of the holding lines 11 and 12 to a winding-up line.
Blocks 3 and 14 are an integral block B as shown by a two-dot chain line.
1 and B2. The valve device 20 includes a first switching valve 2 attached to the first counterbalance valve 5.
1, a second switching valve 22 attached to the second counter balance valve 6, and first and second switching valves 21, 22.
And a pipe 23 to which both ends are connected. The blocks B1 and B2 of the counter balance valves 5 and 6 and the blocks B3 and B4 of the switching valves 21 and 22 are integrally mounted on the blocks B5 and B6 of the hydraulic motors 2 and 3 without using an external pipe or the like. , Hydraulic motor assemblies 2A and 3A are formed as shown by two-dot chain lines.

The spool 1 of the first counterbalance valve 5
The spring-side pilot chamber 17a of the first switching valve 21
Pilot room 1 connected to one of the secondary ports and the other side
7b is connected to the pipeline 24 on the downstream inflow side. The spring-side pilot chamber 18a of the spool 18 of the second counterbalance valve 6 is connected to the secondary port of the second switching valve 22, and the opposite pilot chamber 18b is connected to the holding pipe 12. . The spools 17, 18 are opened and closed according to the difference (pressure difference) between the pilot pressure acting on the pilot chambers 17a, 18a and the pilot pressure acting on the pilot chambers 17b, 18b. Numeral 18 is opened against the spring force, and the flow in the downward direction is allowed. When the pressure difference falls below the spring force, the spools 17, 18 are shut off by the spring force, and the flow in the downward direction is prevented.

The first and second switching valves 21 and 22 are two-position three-port switching valves of a hydraulic pilot type, and a pilot chamber 21 is provided on the spring side and on the opposite side of the spring, respectively.
a, 21b, 22a, and 22b are provided. The switching valves 21 and 22 are switched according to the difference between the pilot pressure acting on the pilot chambers 21a and 22a and the pilot pressure acting on the pilot chambers 21b and 22b, and when the pressure difference becomes larger than the spring force due to breakage of the pipe 23 or the like. , Switching valve 2
1 and 22 are switched to the position (a) against the spring force. When the pressure difference falls below the spring force, the switching valves 21 and 22 are switched to the position (b). The primary port of the first switching valve 21 is connected to the holding pipeline 11 and the pilot chamber 21b, one of the secondary ports is connected to the pilot chamber 17a of the spool 17, and the other is connected to the pipe 23 and the pilot chamber of the switching valve 21. It is connected to the chamber 21a. One of the primary ports of the second switching valve 22 is connected to the holding pipeline 12 and the pilot chamber 22 b of the switching valve 22, and the other is connected to the pipe 23 and the pilot chamber 22 a of the switching valve 22. The secondary port of the second switching valve 22 is connected to the spring-side pilot chamber 18 a of the spool 18.

Next, the operation of the hydraulic winch safety device according to the first embodiment will be described more specifically. (1) During normal operation During normal operation without damage to the pipe 23, when the operating lever 7 is hoisted, the pilot valve 8A is driven in accordance with the operation amount, and the pressure oil from the hydraulic source 9 is supplied to the direction control valve. The directional control valve 4 is supplied to the pilot chamber 4A, and is switched to the position (A). As a result, the pressure oil from the hydraulic pump 1 is supplied to the directional control valve 4 and the check valve 1 respectively.
The hydraulic motors 2 and 3 are supplied to the hydraulic motors 2 and 3 via the holding pipes 5 and 16 and the holding pipelines 11 and 12, and are driven in the hoisting direction. In this case, the same drive pressure acts on each of the hydraulic motors 2 and 3, and the winch drum 58 is driven up by the synchronous drive of the hydraulic motors 2 and 3.

When the operation lever 7 is lowered, the pilot valve 8B is driven in accordance with the operation amount, and pressure oil from the hydraulic pressure source 9 is supplied to the pilot chamber 4B of the direction control valve 4.
The direction control valve 4 is switched to the position (B). Thus, the pressure oil from the hydraulic pump 1 is supplied to the hydraulic motors 2 and 3 via the direction control valve 4 and the pipelines 24 and 25, respectively. At the beginning of the supply of the pressure oil, the passages 11 and 12 on the outflow side of the hydraulic motors 2 and 3 are connected to the spools 17 and 18.
, The rotation of the hydraulic motors 2 and 3 is stopped, and the pressure in the lines 24 and 25 and the holding lines 11 and
Both pressures in 12 increase. At this time, since the same pilot pressure acts on the pilot chambers 21a and 21b of the first switching valve 21, the first switching valve 21 is switched to the position (b), and the spring of the spool 17 is Only force acts. Therefore, when the pilot pressure acting on the pilot chamber 17b of the spool 17 increases due to the increase in the pressure in the pipeline 24, the spool 17 is opened against the spring force, and the pressure oil in the holding pipeline 11 is released from the spool 17.
Pass through. As a result, the holding pressure in the holding pipeline 11 decreases.

At this time, the pilot pressure which is the holding pressure of the holding pipe line 11 is applied to the pilot chamber 22a of the second switching valve 22 through the first switching valve 21, and
A pilot pressure, which is a holding pressure of the holding pipe 12, acts on the pilot chamber 22b. Then, since the holding pressures of the holding pipelines 11 and 12 are substantially equal, the second switching valve 22 is switched to the position (b). As a result, the pressure in the holding pipe line 11 supplied via the first switching valve 21, the pipe 23, and the second switching valve 22 and the spring force act on the spring side of the spool 18, and the spring force is applied. On the opposite side of the holding line 12
The pressure inside acts. Here, when the supply of the pressure oil to the hydraulic motors 2 and 3 is started, as described above, the holding pipeline 1
The pressures in the insides 1 and 12 are high and substantially equal to each other, and the spool 18 is closed by a spring force. When the first hydraulic motor 2 starts rotating and the pressure in the holding pipeline 11 decreases, the force acting on the spring side of the spool 18 becomes smaller, the spool 18 is opened, and the spool 18 in the holding pipeline 12 is opened. Pressure oil passes through the spool 18. Thereby, the pressure in the holding line 12 also decreases. When the pressure in the holding line 12 becomes smaller than the pressure in the holding line 11, the spool 18 is closed and the pressure in the holding line 12 increases. In this way, the spool 18 is opened and closed according to the pressure difference between the holding pipelines 11 and 12, and the holding pressures of the hydraulic motors 2 and 3 are made equal to each other. That is, the hydraulic motors 2 and 3 are driven synchronously in the lowering direction, and the winch drum 58 is driven by the synchronous drive.
Is driven down.

(2) When the pipe 23 is damaged If the pipe 23 is damaged for any reason during the operation,
3, the pressure in the first switching valve 2 decreases to the atmospheric pressure at a stretch.
Both the first and second switching valves 22 are switched to the position (a). When the first switching valve 21 is switched to the position (A), the pipe 23 and the holding pipe 11 are shut off, and the holding pipe 1
1 through the first switching valve 21
To the spring-side pilot chamber 17a. At the time of unwinding, the pressure in the holding pipeline 11 is higher than the pressure in the pipeline 24,
The force acting on the spring side of the spool 17 becomes larger,
The spool 17 is closed, and the rotation of the first hydraulic motor 2 is prevented. On the other hand, when the second switching valve 22 is switched to the position (a), the pipe 23 and the spring-side pilot chamber 18a of the spool 18 are shut off, and the pressure in the holding pipeline 12 passes through the second switching valve 22. And the spring side pilot chamber 18a
It is led to. As a result, the spool 18 is closed by the spring force, and the rotation of the second hydraulic motor 3 is prevented.

As described above, according to the first embodiment, the switching valves 21 and 22 are provided corresponding to the first counterbalance valve 5 and the second counterbalance valve 6, respectively. The holding pipe 11 in the first counterbalance valve 5 and the pilot chamber 18 a of the spool 18 of the second counterbalance valve 6 are connected via a pipe 23, and the pressure in the holding pipes 11 and 12 and the pressure in the pipe 23 are adjusted. The switching valves 21 and 22 are switched according to the difference from the pressure. Thereby, when the piping is broken, the switching valves 21 and 22 are switched,
The communication between the pipe 23 and the holding pipe 11 and the communication between the pipe 23 and the pilot chamber 18a are interrupted to prevent leakage of pressure oil from the hydraulic circuit, and by switching the switching valves 21 and 22, the holding pipe 11, The pressure oil from 12 is guided to the spring side pilot chambers 17a, 18a of the spools 17, 18, respectively, and the spools 17, 18 are closed. as a result,
There is no need to perform adjustment work like a band type brake,
The rotation of the hydraulic motors 2 and 3 can be reliably stopped by the hydraulic brake force.

Second Embodiment FIG. 2 is a hydraulic circuit diagram showing a configuration of a safety device for a hydraulic winch according to a second embodiment of the present invention. The same portions as those in FIG. 1 are denoted by the same reference numerals, and the differences will be mainly described below. In the second embodiment, a first switching valve 26 is provided instead of the first switching valve 21, and a second switching valve 27 is provided instead of the second switching valve 22.

As shown in FIG. 2, the first switching valve 26 is a two-position, four-port switching valve of a hydraulic pilot type, and has pilot chambers 26a, 2a on its spring side and on the side opposite to the spring.
6b are provided respectively. One of the primary ports of the switching valve 26 is connected to the pilot chamber 17 b of the spool 17, and the other is connected to the holding pipeline 11 and the pilot chamber 26 b of the switching valve 26. One of the secondary ports is connected to the spring-side pilot chamber 17a of the spool 17, and the other is connected to the pipe 23 and the spring-side pilot chamber 26a of the switching valve 26. The second switching valve 27 is a two-position three-port switching valve of a hydraulic pilot type, and a pilot chamber 27b is provided on the opposite side of the spring. One of the primary ports of the switching valve 27 is connected to the holding pipeline 12, and the other is connected to the pipe 23 and the pilot chamber 27 b of the switching valve 27.
And connected to. The secondary port is connected to a spring-side pilot chamber 18a of the spool 18.

During normal operation, the same pilot pressure acts on the pilot chambers 26a and 26b of the first switching valve 26, so that the first switching valve 26 is in the position (b).
Is switched to. When the switching valve 26 is switched to the position (B), the pressure oil from the holding line 11 is supplied to the first switching valve 2.
6. The pipe is guided to the pilot chamber 27b of the second switching valve 27 via the pipe 23, and the second switching valve 27 is switched to the position (a). Thereby, the pressure oil from the holding pipeline 11 is guided to the spring-side pilot chamber 18 a of the spool 18. That is, as long as the pipe 23 is not damaged, the first and second switching valves 26 and 27 are at the positions shown in FIG. 2 respectively, and the pressure of the holding line 12 is maintained as in the first embodiment.
Hydraulic motors 2 and 3 are tuned and driven to be substantially equal to the pressure of 1.

When the pipe 23 is damaged, the first switching valve 26
Is switched to the position (a) by the pilot pressure acting on the pilot chamber 26b, and the second switching valve 27 is switched to the position (b) by the spring force. When the first switching valve 26 is switched to the position (A), the pipe 23 and the holding pipe 1
1 is shut off, and the pilot chamber 17a and the pilot chamber 17b of the spool 17 communicate with each other. As a result, the force acting on the spring side of the spool 17 increases by the amount of the spring force, and the spool 17 is closed to prevent the rotation of the first hydraulic motor 2. When the second switching valve 27 is switched to the position (b), the pipe 23 and the pilot chamber 18a of the spool 18 are shut off, and the pilot chamber 18a of the spool 18 and the pilot chamber 18b communicate with each other. As a result, the force acting on the spring side of the spool 18 increases by the amount of the spring force, and the spool 18 is closed and the second
Of the hydraulic motor 3 is blocked.

As described above, according to the second embodiment, the first switching valve 26 is provided in place of the first switching valve 21, and the second switching valve 27 is provided in place of the second switching valve 22. When the pipe 23 is broken, the switching valves 26 and 27 are switched to switch the pilot chambers 17a and 17 on both sides of the spools 17 and 18.
Since the same pilot pressure is applied to b and 18a, 18b, the force acting on the spring side of the spools 17, 18 surely increases by the spring force.
As a result, the spools 17 and 18 are securely closed, and the rotations of the hydraulic motors 2 and 3 can be reliably stopped.
Further, when the pipe 23 is broken, the second switching valve 27 is switched by a spring force instead of a hydraulic pressure, so that adverse effects such as a switching delay due to the hydraulic pressure can be prevented.

Third Embodiment FIG. 3 is a hydraulic circuit diagram showing a configuration of a safety device for a hydraulic winch according to a third embodiment of the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and the differences will be mainly described below. In the third embodiment, a first switching valve 28 is provided instead of the first switching valve 26. The spring-side pilot chamber 17 of the spool 17 is also provided.
a is omitted.

As shown in FIG. 3, the first switching valve 28 is an on-off valve of a hydraulic pilot type, and pilot chambers 28a and 28b are provided on the spring side and the opposite side of the spring, respectively. The primary port of the switching valve 28 is connected to the holding line 11 and the pilot chamber 28b of the switching valve 28,
The secondary port is connected to the pipe 23 and the spring-side pilot chamber 28a of the switching valve 28. During normal work, the first
Since the same pilot pressure acts on the pilot chambers 28a and 28b of the switching valve 28, the fifth switching valve 2
8 is switched to the position (b) and the second switching valve 2
7 is switched to the position (a) as described above. As a result, the pressure oil from the holding pipe 11 is released from the spool 1 during the normal operation as in the first and second embodiments described above.
8 and the hydraulic motors 2 and 3 are tuned.

When the pipe 23 is damaged, the first switching valve 28
Is switched to the position (a) by the pilot pressure acting on the pilot chamber 28b, and the piping 23 and the holding pipeline 11 are shut off. At this time, the spool 17 remains open, and the first hydraulic motor 2 is driven down. on the other hand,
Since the second switching valve 27 is switched to the position (b),
The spool 18 is closed, and the rotation of the second hydraulic motor 3 is stopped. As a result, the first hydraulic motor 2 and the second hydraulic motor 3 are not driven in synchronization, and the behavior of the suspended load becomes unnatural. By visually recognizing the unnatural behavior, the operator determines that some abnormality has occurred, and returns the operation lever 7 to the neutral position. When the operating lever 7 is returned to the neutral position, the direction switching valve 4 is switched to the neutral position, the flow in the lowering direction is blocked, and the rotation of the hydraulic motors 2 and 3 is prevented.

As described above, according to the third embodiment, the first switching valve 28 (open / close valve) is provided instead of the first switching valve 26 by omitting the pilot chamber 17 a of the spool 17.
When the pipe is broken, the suspended load is rolled down with an unnatural behavior.
, The flow of the pressure oil is blocked by the direction control valve 4 and the rotation of the hydraulic motors 2 and 3 can be reliably stopped. According to the third embodiment, the configuration of the hydraulic circuit is simplified as compared with the first and second embodiments.

Fourth Embodiment FIG. 4 is a hydraulic circuit diagram showing a configuration of a safety device for a hydraulic winch according to a fourth embodiment of the present invention. The same portions as those in FIG. 3 are denoted by the same reference numerals, and the differences will be mainly described below. In the fourth embodiment, a first switching valve 29 is provided instead of the first switching valve 28. Further, a brake drum 58c and a braking device 30 for braking the brake drum 58c are added.

As shown in FIG. 4, the braking device 30 includes an electromagnetic switching valve 32 that is switched by turning on and off a changeover switch 31, a brake cylinder 33 that expands and contracts with pressure oil from a first switching valve 29. And a link 34 that is turned around a turning axis by the expansion and contraction of the brake cylinder 33. The brake drum 58c is provided integrally with the winch drum 58, and both rotate integrally.
A plurality of engagement portions 35 are formed at equal intervals on the outer periphery of the brake drum 58c, and the tips of the links 34 can be locked to the engagement portions 35. The tip of the link 34 is the engagement portion 35
, The rotation of the drum 58c in the lowering direction is prevented.

The first switching valve 29 is a two-position, five-port switching valve of a hydraulic pilot type, and pilot chambers 29a and 29b are provided on its spring side and on the side opposite to the spring, respectively. The first primary side port of the switching valve 29 is connected to the holding pipe line 11 and the pilot chamber 29b of the switching valve 29, the second primary side port is connected to the tank, and the third primary side port is electromagnetically switched. Each is connected to a secondary port of the valve 32. One of the secondary ports of the switching valve 29 is connected to the pipe 23 and the spring-side pilot chamber 29 a of the switching valve 29, and the other is connected to the rod-side oil chamber of the brake cylinder 33.

At the time of normal operation, the same pilot pressure acts on the pilot chambers 29a and 29b of the first switching valve 29, so that the first switching valve 29 is switched to the position (b). As a result, the pressure oil from the holding pipeline 11 is guided to the pilot chamber 18a of the spool 18, and the hydraulic motors 2 and 3 are synchronously driven in the same manner as described above. As described later, the changeover switch 31 is turned on and the brake drum 5 is turned on.
If 8c is left free, the winch drum 58 is driven down by driving the hydraulic motors 2 and 3. When the changeover switch 31 is turned on, the electromagnetic switching valve is switched to the position (b), and the pressure oil from the hydraulic pressure source 9 is supplied to the rod side oil chamber of the brake cylinder 33 via the electromagnetic switching valve 32 and the first switching valve 29. Is done. The supply of the pressure oil causes the brake cylinder 33 to contract against the spring force, whereby the tip of the link 34 is disengaged from the engagement portion 35, and the hydraulic motors 2, 3
The winch drum 58 is driven down by the rotation of.

If the pipe 23 is damaged in this state, the first switching valve 29 is switched to the position (a) by the pilot pressure acting on the pilot chamber. By this switching, the pipe 23 and the holding pipe line 11 are cut off, the brake cylinder 33 and the electromagnetic switching valve 32 are cut off, and the rod-side oil chamber of the brake cylinder 33 passes through the first switching valve 29 to the tank. Is communicated to. As a result, the brake cylinder 33 expands and contracts, and the tip of the link 34 is locked by the engaging portion 35a, so that the rotation of the winch drum 58 is prevented.

As described above, according to the fourth embodiment, the first switching valve 29 which is switched according to the pressure difference between the holding pipeline 11 and the pipe 23, and the brake cylinder which expands and contracts by switching the switching valve 29. 33 and a brake drum 58c that rotates integrally with the winch drum 58. The distal end of the link 34 is locked to the engaging portion 35 on the outer periphery of the drum 58c by the expansion and contraction of the cylinder 33, so that the rotation of the drum 58c is stopped. Accordingly, the winch drum 58 can be automatically stopped without returning the operation lever 7 when the piping is broken. In this case, the drum 58 can be mechanically stopped without using the oil pressure.

In the above embodiment, when the pipe is broken, the pressure oil from the holding pipe lines 11 and 12 is supplied to the switching valves 21 and
The counter balance valves 5 and 6 are guided to the spools 17 and 18 via the spools 2, 26 and 27, but are not limited thereto.
For example, pressure oil from a hydraulic pressure source is supplied to switching valves 21, 22, 26, 2
Alternatively, it may be guided directly to the spools 17, 18 via.

[0034]

As described in detail above, claim 1
According to the second aspect of the present invention, the switching valve is provided between the first holding pipe line and the pipe formed by the first counterbalance valve and the second holding pipe line and the pipe formed by the second counterbalance valve. When the pressure in the pipe is reduced, the first and second holding pipelines are disconnected from the pipe by switching the switching valve, and the first and second counterbalance valves are respectively closed. Therefore, the drum can be reliably stopped by the hydraulic brake force when the pipe is broken.

According to the third aspect of the present invention, the first holding pipeline and the pipe formed by the first counterbalance valve and the second holding pipeline formed by the second counterbalance valve are provided. A switching valve is provided between each pipe,
When the pressure in the piping decreases, the first valve is switched by switching the switching valve.
And the second holding pipeline and the pipe are cut off, respectively, and the second counterbalance valve is closed, so that when the pipe is broken, the suspended load slowly unwinds due to unnatural behavior. When the operator who recognizes the operation returns the operation lever, the flow of the pressure oil is blocked by the direction control valve, and the rotation of the hydraulic motor can be surely stopped.

Further, according to the fourth aspect of the present invention, the brake device is braked by the pressure oil delivered by switching the first switching valve due to the pressure drop in the pipe, and the brake drum rotates integrally with the winch drum. As described above, the rotation of the hydraulic motor can be stopped without the operator having to return the operation lever when the piping is broken.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a configuration of a safety device for a hydraulic winch according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a configuration of a safety device for a hydraulic winch according to a second embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram showing a configuration of a hydraulic winch safety device according to a third embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram showing a configuration of a hydraulic winch safety device according to a fourth embodiment of the present invention.

FIG. 5 is a side view of a hydraulic crane to which the present invention is applied.

[Description of Signs] 1 Hydraulic pump 2 First hydraulic motor 3 Second hydraulic motor 4 Directional control valve 5 First counterbalance valve 6 Second counterbalance valve 7 Operation lever 11,12 Holding pipeline 17,18 Spool 21,26,28,29 1st
Switching valve 22, 27 Second switching valve 23 Piping 30 Braking device 58 Winch drum 58c Brake drum

Claims (4)

[Claims] A first hydraulic motor driven by pressure oil from a hydraulic pump; a winch drum driven up and down by driving torque from the first and second hydraulic motors; The first hydraulic motor is formed by forming a first holding pipeline in a drive circuit on the downstream side of the first hydraulic motor in a lowering direction, and maintaining the pressure of the first holding pipeline at a predetermined pressure by opening and closing operation. A first counterbalance valve for restricting the rotation of the second hydraulic motor in a lowering direction; and a second holding pipeline formed in a driving circuit on the lowering direction outflow side of the second hydraulic motor. A second counterbalance valve for controlling the pressure of the holding line to be substantially equal to the pressure of the first holding line to limit the lowering rotation of the second hydraulic motor; Pressure of the holding line of the second counter balance A safety device for a hydraulic winch, comprising: a pipe for guiding the first holding pipe, wherein the first holding pipe is provided between the first holding pipe line and the pipe, and is switched by a pressure drop in the pipe. A first switching valve that shuts off a passage from the pipe and sends pressure oil for closing the first counterbalance valve to the first counterbalance valve; and the second holding pipeline. For switching between the second holding pipeline and the piping, and for closing the second counterbalance valve while being switched by the pressure drop in the piping. And a second switching valve for sending pressure oil to the second counterbalance valve. 2. The safety device for a hydraulic winch according to claim 1, wherein the first counterbalance valve is closed by a pressure of the first holding conduit guided by switching of the first switching valve. The safety device for a hydraulic winch, wherein the second counterbalance valve is closed by the pressure of the second holding conduit guided by switching of the second switching valve. A first and a second hydraulic motor driven by hydraulic oil from a hydraulic pump; a winch drum driven to hoist and lower by a driving torque from the first and second hydraulic motors; The first hydraulic motor is formed by forming a first holding pipeline in a drive circuit on the downstream side of the first hydraulic motor in a lowering direction, and maintaining the pressure of the first holding pipeline at a predetermined pressure by opening and closing operation. A first counterbalance valve for restricting the rotation of the second hydraulic motor in a lowering direction; and a second holding pipeline formed in a driving circuit on the lowering direction outflow side of the second hydraulic motor. A second counterbalance valve for controlling the pressure of the holding line to be substantially equal to the pressure of the first holding line to limit the lowering rotation of the second hydraulic motor; Pressure of the holding line of the second counter balance A safety device for a hydraulic winch, comprising: a pipe for guiding the first holding pipe, wherein the first holding pipe is provided between the first holding pipe line and the pipe, and is switched by a pressure drop in the pipe. A first switching valve for shutting off a passage and the pipe; and a second switching pipe provided between the second holding pipe and the pipe, and switched by a decrease in pressure in the pipe to form the second holding pipe. And a second switching valve that shuts off the piping and the pressure oil for closing the second counterbalance valve and sends the pressure oil to the second counterbalance valve. Safety equipment. 4. The safety device for a hydraulic winch according to claim 3, wherein a brake drum rotating integrally with the winch drum and a pressure delivered by switching the first switching valve due to a pressure drop in the pipe. A brake device that operates with oil to brake the rotation of the brake drum.