JPH09175777A - Automatic stop device of crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load swing generated at the operation time of a hook block position detection means. SOLUTION: This device is provided with a hook block position detection means for operating a microswitch part 34 closely by bringing up a weight 31 hung on the microswitch part 34 when the hook block is wound up to the upper position set in advance and can stop the hydraulic motor 4 for wind up winch driving by detecting the excess winding of the hook block by this hook block position detection means. At the open operation time of the microswitch 34, it is controlled by a slow stop, slow start controller 1 that a drive current outputted to an electromagnetic proportion valve 21 is reduced gradually and a pilot pressure outputted to the left side signal receiving part of a direction flow rate control valve 3 from a pilot valve 5 is reduced gradually. Thereby, the direction flow rate control valve 3 is changed over to a neutral position gradually and closed and the hydraulic motor 4 for wind up winch driving is stopped slowly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hook block position detecting means that operates by detecting that a hook block has been wound up to a preset upper position, and a hoisting winch when the hook block position detecting means operates. And a hydraulic motor stop mechanism for stopping the hydraulic motor for driving,
The present invention relates to an automatic stopping device for a crane, which prevents the hook block from being excessively hoisted by a hoisting winch.

[0002]

2. Description of the Related Art A crane winds and hoists a hoisting rope wound around a boom with a hoisting winch and vertically transfers a suspended load attached to a hook block of the hoisting rope. In this way, when the hoisting load is transferred, if the hoisting rope is wound up and the hoisting load is excessively taken up when the hoisting load is transferred upward, the hook block provided on the hoisting rope collides with the boom top. It is dangerous because it may damage the boom and even pull the boom backward. For this reason, conventional cranes detect excessive winding of the hook block to stop the drive of the hoisting winch and prevent the excessive winding of the hook block. There was an automatic stop device for the crane called. The present invention seeks to ameliorate the problems associated with such automatic crane stop devices.

Therefore, the construction of an automatic stopping device for a crane that has been generally used in the past will be described below with reference to FIGS. 7 and 8. FIG. 7 is a perspective view showing a main part of a crane provided with a conventional crane automatic stop device, and FIG. 8 is a hydraulic electric circuit diagram showing a control system of the conventional crane automatic stop device.

In FIG. 7, reference numeral 42 denotes a hoisting rope wound around the boom via a sheave 41 provided on the boom top,
Reference numeral 43 denotes a hook block attached to the lower end of the hoist rope 42 for hanging a hanging load 44. The hoisting rope 42 can be carried up and down by a hoisting winch (not shown) so that the suspended load 44 hooked on the hook block 43 can be transferred vertically. The crane has a hoisting rope 42 and a hoisting winch for winding the hoisting rope 42, and a hoisting winch driving hydraulic motor 4 for driving the hoisting winch (see FIG. 8 described in detail later).

Reference numeral 31 is a doughnut-shaped weight having a hoisting rope insertion hole for inserting the hoisting rope 42 in the center, 3
Reference numerals 2 and 33 are suspension ropes for suspending the weight 31 for suspending the weight 31, 34 is a hydraulic motor stop mechanism for stopping the hydraulic motor 4 for driving the hoisting winch, and excessive winding of the hook block 43 is performed. It is a micro switch part to prevent it, and it is arranged on the boom side. The weight 31 is inserted so as to be vertically movable with respect to the hoisting rope 42, and the boom 1 is suspended by using the hanging ropes 32 and 33 for suspending the weight.
It is hung from the contact drive section of the micro switch section 34 so as to be located a predetermined distance below the top of the micro switch section 34. Under this state, the micro switch section 34 is
The contact is closed. Since the weight 31 is inserted so as to be able to move up and down with respect to the hoisting rope 42, when the hook block 43 provided on the hoisting rope 42 is excessively wound up and reaches a preset upper position, It is lifted by this hook block 43. As a result, the tension of the suspension ropes 32 and 33 acting on the micro switch portion 34 due to the suspension of the weight 31 until now does not act, so that the micro switch portion 34 opens the contact of the switch and the hydraulic pressure. Activate the motor stop mechanism. As described above, the means configured by the weight 31, the hanging ropes 32 and 33 for hanging the weight, and the microswitch unit 34 detect that the hook block 43 is wound up to the preset rising position. Therefore, it functions as a hook block position detecting means. By detecting the hoisting position of the hook block 43 by the hook block position detecting means, the hydraulic motor stop mechanism is operated to stop the drive of the hoisting winch, and the hook block 43 collides with the top of the boom. Can be prevented in advance.

Next, a specific example of the conventional automatic crane stopping device for operating the hydraulic motor stopping mechanism using the position detecting means will be described with reference to the circuit diagram of FIG. The circuit diagram of FIG. 8 shows a state in which the contacts of the micro switch unit 34 are opened and the hydraulic motor stop mechanism is activated. In FIG. 8, the parts denoted by the same reference numerals as those in FIG. 7 represent the same parts as those in FIG.

In FIG. 8, reference numeral 3 denotes a hydraulic pilot operation system in which a predetermined port is opened / closed by switching from a neutral position to a right position or a left position to control a flow rate and a flow direction of pressure oil supplied to a hydraulic motor 4 described later. Directional flow control valve,
Reference numeral 4 is a hydraulic motor for driving a hoisting winch, 5 is a pilot valve for outputting hydraulic pilot pressure to the left and right signal receiving portions of the directional flow control valve 3 by operating the operation lever, and 8 is a hoisting machine. A hydraulic pump for a hydraulic motor as a hydraulic power source for driving a hydraulic motor 4 for driving a winch, 9 is a pilot hydraulic pump for generating a hydraulic pressure to be supplied to a pilot valve 5 described later, and 10 is an oil tank. . The directional flow control valve 3 is controlled to stop the supply of pressure oil from the hydraulic pump 8 to the hydraulic motor 4 for driving the hoisting winch at the neutral position, and is switched to the left position and the right position to switch the hydraulic pump 8 to the right position. Pressure oil can be supplied to the hydraulic motor 4 in the forward and reverse directions, respectively, and the hydraulic motor 4 can be controlled to drive in the forward and reverse desired directions. Then, when switched to the left position, the hoisting rope 42 is wound up by the hoisting winch and the hook block 43 is wound up, and when switched to the right position, the hoisting rope 42 is unwound and the hook block 43 is unwound by the hoisting winch. . The pilot valve 5 outputs a pilot pressure to the left and right signal receiving portions of the directional flow control valve 3 for the hydraulic motor by operating the operation lever thereof to the right or left, so that the directional flow control valve 3 is neutralized. By switching from the position to the left position or the right position, the hydraulic motor 4 can be driven in the forward and reverse desired directions. Further, since the pilot pressure to be output can be adjusted according to the operation amount of the operation lever, the opening amount of the directional flow control valve 3 can be adjusted. Therefore, the flow rate of the pressure oil supplied to the hydraulic motor 4 can be adjusted by the operation amount of the operation lever to adjust the drive speed thereof to a desired value.

Reference numeral 22 is an electromagnetic operation which is provided in a pilot line for guiding the hydraulic pilot pressure from the pilot valve 5 to the left signal receiving portion of the directional flow control valve 3 and has a drive coil portion as a signal receiving portion only on the left side. Type solenoid valve,
Reference numeral 61 is a relay coil for energizing the relay contact 62 by energizing when the hook block position detecting means is inoperative, that is, when the micro switch portion 34 is closing the contact of the switch contrary to FIG. The electromagnetic switching valve 22 is usually
Since the micro switch part 34 closes the contact of the switch and closes the relay contact 62, and the drive current flows through the drive coil part of the electromagnetic switching valve 22, it is switched to the left position opposite to that of FIG. The pilot line for guiding the pilot pressure from the pilot valve 5 to the left signal receiving portion of the directional flow control valve 3 is opened. Also, the weight 3
1, when the hook block position detecting means including the micro switch portion 34 and the like operates, and the micro switch portion 34 opens the contact of the switch, as shown in FIG. As shown in FIG. 8, reference numeral 22 is switched to the right position to shut off the pilot conduit for guiding the pilot pressure to the left side signal receiving portion of the directional flow control valve 3 and to the left side signal receiving side of the directional flow control valve 3. The pilot pressure acting on the section is released to the oil tank 10. Therefore, when the electromagnetic switching valve 22 is switched to the right position, the directional flow control valve 3 is in the neutral position even if the operation lever of the pilot valve 5 is operated to the right to switch to the left position. It cannot be switched to the left position, and the drive of the hydraulic motor 4 for winding the hoisting rope 42 is disabled. As described above, in the conventional automatic stop device for a crane, the hydraulic motor stop mechanism that stops the hydraulic motor 4 for driving the hoisting winch when the hook block position detecting means is activated is provided with a directional flow control valve 3 and an electromagnetic switching valve 22.
And a relay coil 61 and a relay contact 62.

Since the conventional automatic stop device for a crane is provided with such a structure, the condition in which the crane is not operated is the reverse of the state shown in FIG. 8, that is, the micro switch 34 closes the switch contact and the relay contact 62 is released. When the directional flow control valve 3 is switched to the left position by operating the operation lever of the pilot valve 5 to the right in the state where it is closed and the electromagnetic switching valve 22 is switched to the left position, the pressure oil of the hydraulic pump 8 is changed. Is supplied to the hydraulic motor 4, and the hydraulic motor 4 is driven at a predetermined speed according to the operation amount of the operating lever to drive the hoisting winch. The hoisting winch winds the hoisting rope 42 and hooks it. Roll up the block 43. When the hook block 43 is excessively wound up and passes through the preset upper position, the weight 31
It is lifted by the hook block 43 to open the micro switch unit 34. Then, by the opening operation of the micro switch unit 34, the relay coil 61 becomes
Since the energization is released and the relay contact 62 is opened as shown in FIG. 8, the electromagnetic switching valve 22 is switched to the right position as shown in FIG. 8 because the driving current does not flow in the driving coil portion. . As a result, the electromagnetic switching valve 22 shuts off the pilot line for guiding the pilot pressure to the left signal receiving portion of the directional flow control valve 3, and the pilot pressure acting on the left signal receiving portion is supplied to the oil tank 10. The hydraulic motor 4 for driving the hoisting winch in order to immediately switch the directional flow control valve 3 to the neutral position and close it.
To prevent the hook block 43 from being excessively wound up.

[0010]

In the conventional automatic stopping device for a crane, when the hook block 43 is about to be excessively hoisted, the hook block position detecting means detects it and drives the hoisting winch. Although the hoisting winch can be prevented from being excessively hoisted by suddenly stopping the hydraulic motor 4, the hoisting winch causes a sway when the hoisting winch is hoisted at a particularly high speed. There was a problem that it was dangerous. Further, as the hook block position detecting means, in particular, the weight 3 as described above is used.
In the case of using a unit composed of 1 and the hanging ropes 32 and 33 for hanging the weight and the micro switch unit 34,
Although the hook block 43 may not be wound up excessively, the hook block 43 may stop due to a malfunction, and in such a case, the shake of the load occurs. That is, the hook block 43
When the hoisting rope 42 is hoisted, the hoisting rope 42 makes a circular motion as shown by an arrow in FIG. 9, and at that time, the weight 31 contacting with the hoisting rope 42 rotates and the hoisting rope 32 for suspending the weight is provided.
Since 33 is entangled with the hoisting rope 42 as shown in FIG. 10, the weight 31 is lifted by the entanglement,
It may be momentarily lifted by contact with the hoisting rope 42. When such a malfunction occurs, although the hook block 43 cannot be excessively wound up,
When the micro switch unit 34 operates to suddenly stop the hydraulic motor 4 for driving the hoisting winch, and further, when the malfunction is released, the hydraulic motor 4 suddenly starts up this time, causing a shake of the load. In addition, there is a problem that, among the shakes of the goods due to such a malfunction, the shakes of the goods due to a sudden stop occur suddenly and cannot be predicted, and thus are more dangerous.

The present invention has been made in view of the above problems in the prior art, and an object thereof is to reduce load shake generated when the hook block position detecting means operates. It is to provide an automatic stopping device for a crane that can do so.

[0012]

The above objects of the present invention are as follows:
"A crane having a hoisting rope having a hook block for hanging a suspended load and wound around a boom and a hoisting winch driving hydraulic motor for driving the hoisting winch for winding the hoisting rope And a hook block position detecting means for detecting the fact that the hook block has been wound up to a preset upper position, and a hydraulic motor for driving a hoisting winch when the hook block position detecting means operates. In a crane automatic stop device equipped with a hydraulic motor stop mechanism for controlling a control valve capable of opening and closing a pressure oil supply path for driving a hydraulic motor for driving a hoisting winch, and a control for opening and closing the control valve. The valve operating means and the control valve are opened and closed through the control valve operating means, and the control valve is gradually closed when the hook block position detecting means is operated. By configuring the hydraulic motor stop mechanism in the control valve actuating the speed control means for controlled so,
The hydraulic motor for driving the hoisting winch can be slowly stopped when the hook block position detecting means is activated. "The automatic stopping device for a crane according to claim 1 characterized in that Achieved by

Since the automatic stopping device for a crane according to the present invention has such a structure, when the hydraulic motor for driving the hoisting winch is driven to wind the hook block, the hook block position detecting means operates. When I did
The control valve actuation speed control means stops the supply of pressure oil to the hydraulic motor for driving the hoisting winch while controlling the control valve operating means to gradually close the control valve.
Therefore, according to the automatic stop device for a crane of the present invention, it is possible to gently stop the hydraulic motor for driving the hoisting winch when the hook block position detecting means is operated, and the swing of the load generated when the hook block position detecting means is operated. Can be reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be clarified by describing concrete embodiments showing how the present invention is actually embodied with reference to FIGS. 1 to 6. To do. FIG. 1 is a hydraulic electric circuit diagram showing a control system of an automatic stopping device for a crane according to a first embodiment of the present invention, and FIG.
FIG. 3 is a hydraulic electric circuit diagram showing a control system of a crane automatic stop device according to a second embodiment of the present invention, and FIG. 3 exemplifies characteristics of pilot pressure acting on the directional flow control valve when the hook block position detecting means is activated. FIG.
FIG. 4 is a view similar to FIG. 3 showing a conventional example for comparison with the embodiment of the present invention, and FIG. 5 shows characteristics of pilot pressure acting on the directional flow control valve when the hook block position detecting means is deactivated. FIG. 6 is a diagram similar to FIG. 5 relating to a conventional example for comparison with the exemplary embodiment of the present invention. Similar to the circuit diagram of FIG. 8, the hydraulic electrical circuit diagrams of FIGS. 1 and 2 show a state in which the contacts of the microswitch unit 34 are opened and the hydraulic motor stop mechanism is activated. In FIGS. 1 and 2, the parts denoted by the same reference numerals as those in FIGS. 7 and 8 represent the same parts as those in these drawings, and therefore will not be described in detail to avoid duplication of description.

The automatic stopping device for a crane according to the embodiment of the present invention has a hook block 43 for hanging a suspended load and is wound around a boom in the same manner as the conventional device described with reference to FIGS. 7 and 8. The crane is provided with the upper rope 42 and the hydraulic motor 4 for driving the hoisting winch for driving the hoisting winch for winding the hoisting rope 42. The automatic stop device, like the conventional device, operates by detecting that the hook block 43 has been wound up to a preset upper position, and a hook block position detecting means, and an operation of the hook block position detecting means. A hydraulic motor stop mechanism for stopping the hydraulic motor 4 for driving the hoisting winch is provided, and the hook block position detecting means includes a weight 31, suspension ropes 32 and 33 for suspending the weight, and a microswitch unit 34. The structure is the same as that of the conventional device, except that the structure of the hydraulic motor stop mechanism is different.

Therefore, first, the characteristic structure of the automatic crane stopping device according to the first embodiment of the present invention will be described. In FIG. 1, reference numeral 21 denotes the hydraulic pilot pressure from the pilot valve 5 to the directional flow control valve 3. The electromagnetic proportional valve 1 of the electromagnetic operation system, which is provided in the pilot line for guiding the signal to the left side signal receiving portion and has the drive coil portion as the signal receiving portion only on the left side, controls the drive current of the solenoid proportional valve 21. Is a slow stop / slow start controller that controls the directional flow control valve 3 to gradually open and close. The solenoid proportional valve 21 is normally switched to the left position opposite to that in FIG. 1 because a current flows through the drive coil portion, and the pilot pressure from the pilot valve 5 is fed to the left side signal of the directional flow control valve 3. Although the pilot conduit for guiding to the receiving portion is open, when it is switched to the right position as shown in FIG. 1, the pilot conduit is shut off and acts on the left signal receiving portion of the directional flow control valve 3. The pilot pressure being released is released to the oil tank 10. Further, when the solenoid proportional valve 21 is switched to the left position, it is possible to control so as to reduce the secondary pressure according to the current value by reducing the drive current flowing to the drive coil portion. . Therefore, the hydraulic pilot pressure output from the pilot valve 5 is reduced to a desired value and guided to the left side signal receiving portion of the directional flow control valve 3 by controlling the drive current flowing to the drive coil portion. Can be

The slow stop / slow start controller 1 functions to control the drive current flowing to the drive coil portion of the solenoid proportional valve 21. Then, when the hook block position detecting means is inoperative, that is, when the micro switch portion 34 closes the contact of the switch, which is the opposite of FIG.
The drive current is output to the drive coil section of, and this is switched to the left position. Further, the output drive current is also set to a large value so as not to reduce the secondary pressure of the solenoid proportional valve 21. On the other hand, this slow stop / slow start controller 1
When the micro switch unit 34 opens the contact of the switch as shown in FIG. 1, the drive current output to the drive coil unit of the solenoid proportional valve 21 is not immediately interrupted but gradually reduced and interrupted. When controlled, the solenoid proportional valve 21 is switched to the right position as shown in FIG. As a result, when the micro switch unit 34 is opened, the secondary pressure of the solenoid proportional valve 21, that is, the pilot pressure acting on the left signal receiving portion of the directional flow control valve 3 in the device of this embodiment is shown in FIG. As shown in FIG. 3, it is possible to control the value so that it is gradually decreased to 0 as shown in FIG. Further, from such a state, when the microswitch unit 34 closes the contact of the switch again, the drive current is output to the drive coil unit of the solenoid proportional valve 21, but in that case, the drive current is suddenly set to a large value. Without doing anything, it is controlled to gradually increase to a large value. As a result, when the micro switch portion 34 is closed, the secondary pressure of the solenoid proportional valve 21, that is, the pilot pressure acting on the left signal receiving portion of the directional flow control valve 3 is suddenly changed as in the characteristic of the conventional device of FIG. Instead of setting the steady-state value, it is possible to control the value to gradually increase to the steady-state value as illustrated in FIG. In this way, the solenoid proportional valve 21 functions as an operating means of the directional flow control valve 3 for opening and closing the directional flow control valve 3, and the slow stop / slow start controller 1 controls the directional flow rate through this operating means. It functions as an operating speed control means for the directional flow control valve 3 that controls the valve 3 to open and close and gradually close when the hook block position detecting means operates.

Since the automatic stopping device for a crane according to the first embodiment of the present invention has such a structure, it is in a state opposite to that shown in FIG. 1 in which the crane is not currently operated, that is,
When the micro switch 34 closes the contact of the switch and the solenoid proportional valve 21 is switched to the left position, the pilot valve is operated to switch the directional flow control valve 3 to the left position to drive the hoisting winch. Assuming that the hydraulic motor 4 is driven to excessively wind up the hook block 43, the weight 31 is lifted by the hook block 43 and lifted up by the micro switch unit 3 as in the conventional device.
4 is opened. Then, by the opening operation of the micro switch unit 34, the slow stop / slow start controller 1
Causes the drive current output to the drive coil portion of the solenoid proportional valve 21 to be gradually reduced to 0, and the solenoid proportional valve 21 is switched to the right position as shown in FIG. Meanwhile, pilot valve 5
The pilot pressure output from the directional flow control valve 3 to the left side signal receiving portion is blocked while being controlled so as to gradually decrease as illustrated in FIG.
Is gradually switched to the neutral position and closed, and stops the supply of pressure oil from the hydraulic pump 8 to the hydraulic motor 4 for driving the hoisting winch. In addition, the hook block 43
Even when the weight 31 is lifted due to a malfunction such as contact with the hoisting rope 42 in the process of hoisting, the directional flow control valve 3 is similarly gradually switched to the neutral position and transferred to the hydraulic motor 4. Stop supplying the pressure oil. Therefore, according to the device of the present embodiment, the hydraulic motor 4 for driving the hoisting winch can be gently stopped when the hook block position detecting means is operated, and the load shake generated when the hook block position detecting means is operated. Can be reduced.

On the other hand, when the hook block position detecting means operates due to such a malfunction and the malfunction is released and the microswitch unit 34 closes the contact of the switch again, the slow stop / slow start controller 1
Outputs a drive current to the drive coil portion of the solenoid proportional valve 21 and controls it so as to gradually increase it to a large value, and switches the solenoid proportional valve 21 to the left position opposite to that in FIG. As a result, the pilot pressure is output again from the pilot valve 5 to the left-side signal receiving portion of the directional flow control valve 3. In that case, the pilot pressure is controlled so as to gradually increase as illustrated in FIG. However, since the value becomes the steady state value, the directional flow control valve 3 is gradually switched from the neutral position to the left position to supply the pressure oil of the hydraulic pump 8 to the hydraulic motor 4 for driving the hoisting winch. Therefore, according to the device of the present embodiment, the hydraulic motor 4 for driving the hoisting winch can be slowly activated when the operation of the hook block position detecting means is released, and this occurs when the operation of the hook block position detecting means is released. It is also possible to reduce load fluctuations.

Next, the characteristic construction of the automatic crane stopping device of the second embodiment of the present invention will be explained. In the device of the second embodiment, the directional flow control valve 3 and the electromagnetic proportional valve 21 for opening / closing the directional flow control valve 3 and the directional flow control valve 3 are gradually added to the device of the first embodiment described above. In contrast to the hydraulic motor stop mechanism composed of the slow stop / slow start controller that controls the opening / closing operation, the directional flow control valve 3 is operated at the normal speed as in the above-mentioned conventional device when the hook block position detecting means is operated. A control valve actuating means for opening and closing is additionally provided so that the control valve actuating means can be selectively used. Therefore, a slow stop / slow start changeover switch 7 is provided in the electric circuit between the switch contact of the micro switch 34 and the slow stop / slow start controller 1 in the device of the first embodiment, and the slow stop is made at one of the changeover contacts. -The slow start controller 1 is connected, and the relay coil 61 is connected to the other switching contact, and at the same time, the relay coil 61 is energized to close and drive the drive coil portion of the solenoid proportional valve 21. A relay contact 62 for passing a current is provided. The relay coil 61 and the relay contact 62 can operate in exactly the same manner as the conventional device when the hook block position detecting means is activated or deactivated, and the relay contact 62 of the solenoid proportional valve 21 is activated during the closing operation. Since a sufficiently large drive current is passed through the drive coil portion, the secondary pressure of the solenoid proportional valve 21 is not reduced.

Since the automatic stopping device for a crane according to the second embodiment of the present invention has such a structure, by switching the slow stop / slow start changeover switch 7, the hook block position detecting means is activated or activated. At the time of release, similar to the device of the first embodiment, the directional flow control valve 3 can be gradually opened and closed to slowly stop or slowly start the hydraulic motor 4 for driving the hoisting winch, or the conventional device. Similarly to the above, the directional flow control valve 3 is opened and closed at a normal speed, and the hydraulic motor 4
Can be slowly stopped or slowly started. As described above, the device of the second embodiment has both the function of the device of the first embodiment and the function of the device that has been conventionally used, so that the effects of the device of the first embodiment can be exhibited. Needless to say, even if a skilled operator who is used to the conventional device uses this, by using the slow stop / slow start changeover switch 7 as necessary, the same operation as the conventional device can be performed. It can be naturally adapted to the device and is easy for everyone to use. Further, even if the slow stop / slow start controller 1 fails during crane work, by switching the slow stop / slow start changeover switch 7, the work can be continued in the same manner as the conventional device, and the work can be continued on site. No need to interrupt work.

The first embodiment and the second embodiment of the present invention described above
In the apparatus of the specific example, the hook block position detecting means detects overwinding of the hook block and slowly stops when stopping the hydraulic motor 4 for driving the hoisting winch. Although the hook block slightly moves up even after the operation of, if the winding position of the hook block at which the hook block position detecting means operates is set appropriately in consideration of such a thing in advance, the hook block will not move slowly. It is possible to prevent the vehicle from ascending and colliding with the boom top when stopped. In the devices of these specific examples, the hydraulic motor 4 for driving the hoisting winch is slowly activated when the malfunction of the hook block position detecting means is released, but it is expected that the malfunction of the hook block position detecting means will occur. Even if it is difficult to cancel the malfunction, the malfunction can be canceled at the time when the malfunction occurs, and when the hook block position detecting means does not use a means such as the weight 31 as in the embodiment, A malfunction due to such means does not occur, and the hydraulic motor 4 is not suddenly started due to the cancellation of the malfunction. Therefore, a configuration such as a specific example in which the hydraulic motor 4 is slowly started is not always necessary for the present invention. Not an essential configuration.

[0023]

As is apparent from the above description, the present invention relates to an automatic stopping device for a crane, and more particularly, to a hydraulic oil stopping mechanism for driving a hydraulic motor for driving a hoisting winch. A control valve that can open and close the supply path of
Control valve operating means for opening and closing the control valve, and control valve operating speed for controlling the control valve to open and close through the control valve operating means and gradually close the control valve when the hook block position detecting means operates. The control valve operating speed control means controls the control valve operating means so as to gradually close the control valve when the hook block position detecting means is operated. According to the crane automatic stop device, the hydraulic motor for the hoisting winch drive can be gently stopped,
It is possible to reduce the load shake that occurs when the hook block position detecting means operates. Further, when the configuration described in claim 5 is adopted when the present invention is carried out, in addition to exhibiting such a song effect, it is easy for everyone to use and control Even if the valve actuation speed control means breaks down during crane work, the work need not be interrupted.

[Brief description of the drawings]

FIG. 1 is a hydraulic electric circuit diagram showing a control system of an automatic stopping device for a crane according to a first embodiment of the present invention.

FIG. 2 is a hydraulic electric circuit diagram showing a control system of a crane automatic stop device according to a second embodiment of the present invention.

FIG. 3 is a diagram relating to a specific example of the present invention illustrating the characteristic of pilot pressure acting on the directional flow control valve when the hook block position detection means is activated.

FIG. 4 is a view similar to FIG. 3 relating to a conventional example for comparison with an embodiment of the present invention.

FIG. 5 is a diagram relating to a specific example of the present invention illustrating the characteristic of pilot pressure acting on the directional flow control valve when the operation of the hook block position detection means is released.

FIG. 6 is a view similar to FIG. 5 for a conventional example for comparison with an embodiment of the present invention.

FIG. 7 is a perspective view showing a main part of a crane provided with a conventional automatic crane stopping device.

FIG. 8 is a hydraulic electric circuit diagram showing a control system of a conventional automatic stop device for a crane.

FIG. 9 is a perspective view of a main part for explaining a process leading to a malfunction of the hook block position detecting means.

FIG. 10 is a perspective view of an essential part showing a state where the hook block position detecting means malfunctions.

[Explanation of symbols]

 1 Slow stop / slow start controller 3 Directional flow control valve 4 Hydraulic motor for hoisting winch drive 5 Pilot valve 7 Slow stop / slow start changeover switch 8 Hydraulic pump for hydraulic motor 9 Hydraulic pump for pilot 21 Electromagnetic proportional valve 31 Weights 32, 33 Hanging ropes for hanging weights 34 Micro switch section 42 Hoisting ropes 43 Hook blocks 61 Relay coils 62 Relay contacts

Claims (5)

[Claims] 1. A hoisting rope having a hook block for hanging a hoisted load and wound around a boom, and a hoisting winch driving hydraulic motor for driving a hoisting winch for winding the hoisting rope. And a hook block position detecting means which is provided on a crane having and which operates by detecting that the hook block has been hoisted to a preset upper position, and a hoisting winch driving device when the hook block position detecting means operates. In a crane automatic stop device including a hydraulic motor stop mechanism for stopping a hydraulic motor, a control valve that can open and close a pressure oil supply path for driving a hydraulic motor for driving a hoisting winch, and this control valve Control valve operating means for opening and closing, and opening and closing the control valve through this control valve operating means, and gradually closing the control valve when the hook block position detecting means operates. By configuring the hydraulic motor stop mechanism with the control valve operating speed control means for controlling to operate the hydraulic motor for the hoisting winch drive when the hook block position detecting means is activated. Crane automatic stop device. 2. The hook block position detecting means has a weight which is inserted through the hoisting rope so as to be vertically movable and is hung from the boom side. The hook block is lifted by the hook block. The automatic stop device for a crane according to claim 1, wherein the automatic stop device is means for detecting that the is wound up to a preset upper position. 3. The control valve operating speed control means also has a function of controlling to gradually open the control valve when the operation of the hook block position detecting means is released. Automatic stop device for cranes. 4. The control valve is a hydraulic pilot operated directional flow control valve operated by a hydraulic pilot pressure output from the pilot valve, and the control valve operating means is
This is a solenoid proportional valve provided in a pilot line for outputting hydraulic pilot pressure to the directional flow control valve, and the control valve actuation speed control means controls the drive current of the solenoid proportional valve to gradually move the directional flow control valve. The automatic stopping device for a crane according to claim 1, 2, or 3, which is a controller for controlling the crane to be closed. 5. The hydraulic motor stop mechanism is provided with a control valve actuating means for closing the control valve at a normal speed when the hook block position detecting means is actuated, and the control valve actuating means can be selectively used. The automatic stop device for a crane according to claim 1, claim 2, claim 3 or claim 4, characterized in that.