JP4289705B2 - Winch overwinding prevention device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winch overwinding prevention device that prevents a winch that winds and unwinds a wire by hydraulic pressure from winding a wire beyond a predetermined position, for example, an overwinding prevention device for a winch mounted on a truck crane or the like. It is related to effective technology.
[0002]
[Prior art]
If the wire is wound around the boom by a winch mounted on a truck crane or the like, the boom or the wire may be damaged. Therefore, a winch mounted on a truck crane or the like is provided with a winch overwinding prevention device. Note that overwinding of the wire is caused not only by overwinding of the wire itself but also by extending or raising the boom while the wire is wound up.
[0003]
The conventional winch overwinding prevention device detects a state in which the wire has been wound up by a predetermined amount during the winch hoisting operation, the boom extension operation, and the boom raising operation, and this detection signal is used to detect the hydraulic pressure. By opening the differential pressure valve provided in the bypass passage connecting the unload passage and the tank passage and connecting the unload passage and the tank passage to make the hydraulic pressure in the unload passage the tank pressure, that is, By making the air pressure, the winch hook is configured not to approach the tip of the boom beyond a predetermined position.
[0004]
[Problems to be solved by the invention]
  In the winch overwinding prevention device described above,Traditionally,The switch detects the valve opening position and the operation direction of the switching valve in the direction in which the wire is wound up, such as winding the winch, extending the boom, and raising the boom.
For this reason, the detection position of the switch mounted for each switching valveWhen operating the neutral position of the switching valve and overwinding directionOpen positionIn the middle ofA great deal of time and money is required for the adjustment work for matching, the environmental measures for mounting the switch, and the wiring work.
[0005]
An object of the present invention is to prevent overwinding of a winch by detecting operation of the switching valve in a direction in which the hook of the winch approaches the tip of the boom without using electric means, and preventing overwinding of the winch. Is to provide.
[0006]
[Means for Solving the Problems]
  The first means is connected between the hydraulic source, the unload passage connected to the hydraulic source, the tank passage connected to the tank from the unload passage, and the unload passage and the tank passage. A winch switching valve for supplying and discharging pressure oil to and from the winch for hoisting and lowering the winch according to the switching operation, a boom expansion and contraction switching valve for supplying and discharging pressure oil to the actuator for extending and retracting the boom, and raising and lowering the boom A boom raising / lowering switching valve for supplying and discharging pressure oil to the actuator to be operated, a bypass passage connecting the upstream side of the winch switching valve of the unload passage to the tank passage, and a normally closed passage interposed in the bypass passage. A differential pressure valve, a pilot passage of the differential pressure valve that is controlled between opening and closing of the differential pressure valve and interposed between the differential pressure valve and the tank passage, and the winch is moved to a predetermined position. A detecting means for outputting a detected signal that it has up operation can, in the over-winding prevention apparatus winch and an electromagnetic valve which is interposed in the pilot passage of the differential pressure valve is opened and closed by a signal of the detection means,
  A winch control valve that is linked to the winch switching valve, and a branch hydraulic passage that branches off from the unload passage and feeds / discharges pressure oil to / from the winch control valve,
The branch hydraulic passage is divided into three branches, and the respective leading ends of the branch paths detect the pump port of the winch control valve for detecting the operation direction of the winch switching valve and the operation direction of the expansion / contraction switching valve. Connected to the pump port of the control valve for expansion and contraction and the pump port of the control valve for undulation detecting the operation direction of the undulation switching valve,
  A winch pilot valve whose opening and closing is controlled by pressure oil discharged from the winch control valve is interposed in the pilot passage of the differential pressure valve.,It is characterized by that.
[0007]
  The second means includes a low pressure relief valve in the pilot passage of the differential pressure valve, and a normally open valve.Low voltage switching electromagneticThe valve is interposed in parallel.
[0008]
A third means is that a branch pilot passage is branched from a pilot passage of the differential pressure valve, and an extension / contraction pilot valve is interposed in the branch pilot passage, and the extension / contraction pilot valve is connected to the extension / contraction switching valve of the boom. Opening and closing is controlled by pressure oil supplied via an expansion / contraction control valve that switches in conjunction.
[0009]
According to a fourth means, a branch pilot passage is branched from the pilot passage of the differential pressure valve, and a undulation pilot valve is interposed in the branch pilot passage, and the undulation pilot valve is connected to the boom switching valve. It is characterized in that the opening and closing is controlled by pressure oil supplied through a relief control valve that switches in conjunction.
[0010]
The fifth means is characterized in that the pressure oil supplied to the winch control valve, the telescopic control valve, and the undulation control valve is supplied by a branch hydraulic passage branched from the unload passage. To do.
[0011]
The sixth means is that pressure oil supplied to the winch control valve, the expansion / contraction control valve, and the undulation control valve is branched from the actuator passages of the winch switching valve, the expansion / contraction switching valve, and the undulation switching valve. It is characterized by being supplied.
[0012]
The seventh means is characterized in that the electromagnetic valve is interposed in a branch hydraulic passage branched from the unload passage.
[0013]
  According to the first means described above, the winch control valve linked to the winch switching valve opens the winch pilot valve in response to the operation in the winding direction of the winch switching valve, and the winch reaches a predetermined amount. When it is wound up and the detection means detects this and outputs a signal,By operation of solenoid valveSince the differential pressure valve opened in the bypass passage between the unload passage and the tank passage opens and connects the unload passage to the tank passage, the winch can be stopped from being wound.
[0014]
  According to the second means described above, after overwinding is detected,SwitchBy operationSwitch the low pressure switching solenoid valve to the closed position, and adjust the pressure when winding the winch to the pressure limited by the low pressure relief valve.Hook in the hanging hookStoreCan be made.
[0015]
According to the third means described above, it is possible to prevent an overwinding state from occurring as the boom extends.
[0016]
According to the fourth means described above, it is possible to prevent an overwinding state from occurring as the boom rises.
[0017]
  According to the fifth means described above, the switching operation of the winch pilot valve, the expansion / contraction pilot valve and the hoisting pilot valve is executed by the pressure oil in the unload branch passage branched from the unload valve.Pump discharge pressureThus, the switching operation can be executed reliably.
[0018]
  According to the sixth means, pressure oil for switching to the winch pilot valve, the telescopic pilot valve and the hoisting pilot valve is supplied from the actuator passages of the winch switching valve, the boom telescopic switching valve and the boom hoisting switching valve. So compared to the fourth meansReliable switching with high pressure oilcan do.
[0019]
According to the seventh means, since the electromagnetic valve is interposed from the pilot passage of the differential pressure valve to the branch hydraulic passage of the unload passage, it is possible to design with a sufficient machining accuracy of the valve.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
In the present embodiment, the winch overwinding preventing device according to the present invention is provided in an operating device (hereinafter referred to as an operating device) 1 for operating the truck crane shown in FIG. The operating device 1 provided with the overwinding prevention device is configured as shown in FIG.
[0022]
The drive of the truck crane is hydraulic, and the operating device 1 includes a boom expansion / contraction switching valve (hereinafter referred to as an expansion / contraction switching valve) 2, a winch hoisting / lowering switching valve (hereinafter referred to as a winch switching valve) 3, and a boom. A hoisting switching valve (hereinafter referred to as a hoisting switching valve) 4, a boom right-turning left-turning switching valve (hereinafter referred to as a turning switching valve) 5, an outrigger up / down switching valve (hereinafter referred to as an outrigger switching valve). ) 6 and 7 are provided. Each of these switching valves 2 to 7 is configured to be manually operated, and is in a neutral position (indicated by the suffix “a” attached to the sign of each switching valve) and switching positions on both sides ( Similarly, subscripts b and c are attached to each other). Each of the switching valves 2 to 7 includes an unload passage 10 to which pressure oil is supplied from the pump 8, a tank passage 11 connected to the tank 9 from the unload passage 10, and a hydraulic actuator (not shown) corresponding to each. Are connected to hydraulic actuator passages A1 to A6 and B1 to B6, respectively, to switch the direction of pressure oil supply to and discharge from each hydraulic actuator.
[0023]
Then, the boom is shortened at the shortened position 2b of the expansion / contraction switching valve 2 and extended at the stretched position 2c. The winch is wound up at the winding position 3b of the winch switching valve 3 and is lowered at the winding position 3c. The boom rises at the rising position 4b of the undulation switching valve 4 and falls at the falling position 4c. The boom turns left at the left turning position 5b of the turning switching valve 5, and turns right at the right turning position 5c. The outrigger moves up at the up-moving positions 6b, 7b of the outrigger switching valves 6, 7, and moves down at the down-moving positions 6c, 7c.
[0024]
A bypass passage 35 that bypasses each switching valve 2 to 7 and communicates with the tank passage 11 is connected to the upstream side of each switching valve 2 to 7 of the unload passage 10. A differential pressure valve 14 that operates by controlling the pressure is interposed. A first pilot passage 36 is interposed between the pilot port 14 a of the differential pressure valve 14 and the tank passage 11, and an electromagnetic valve 15 is interposed in the first pilot passage 36.
[0025]
The electromagnetic valve 15 is configured to be controlled by a limit switch 23. As shown in FIG. 2, the limit switch 23 is installed at the tip of the boom 21, and is configured to detect that a hanging hook (hereinafter referred to as a hook) 22 has approached. Yes.
[0026]
  One end side of the second pilot passage 37 is connected to the upstream side of the electromagnetic valve 15 in the first pilot passage 36, and the other end side of the second pilot passage 37 is connected to the tank passage 11. A high pressure relief valve 16 is interposed in the second pilot passage 37. This high pressure relief valve 16 is opened when a high pressure exceeding the set pressure occurs for some reason in the hydraulic circuit., ManipulationEquipment1 isThis is to prevent breakage. In this embodiment, the relief pressure of the high pressure relief valve 16 is 160 kgf / cm.² Is set to about.
[0027]
  One end side of the third pilot passage 38 is connected to the downstream side of the electromagnetic valve 15 in the first pilot passage 36, and the other end side of the third pilot passage 38 is connected to the tank passage 11. A low pressure relief valve 12 is interposed in the third pilot passage 38. A low pressure switching electromagnetic valve 17 is connected to the third pilot passage 38 in parallel with the low pressure relief valve 12, and the low pressure switching electromagnetic valve 17 is operated by a push button during hook-in operation (operation for storing the hook 22). It is like that.
In this embodiment, the low pressure relief valve12Relief pressure is 50kgf / cm² Is set to about.
[0028]
On the downstream side of the low pressure relief valve 12 in the third pilot passage 38, a normally closed winch pilot valve 18 constituted by a 2-port, 2-position, pilot operated switching valve is connected in series with the low pressure relief valve 12. It is installed. A load port R of the winch control valve 31 is connected to a pilot passage (hereinafter referred to as a winch pilot passage) 40 of the winch pilot valve 18.
[0029]
  One end side of the fourth pilot passage 39 is connected to the downstream side of the solenoid valve 15 in the first pilot passage 36, and the other end side of the fourth pilot passage 39 is connected to the tank passage 11. The fourth pilot passage 39 is provided with a normally closed expansion / contraction undulation pilot valve 19 constituted by a 2-port, 2-position / pilot operation type switching valve. A secondary passage 34a of a shuttle valve 34, which will be described later, is connected to a pilot passage 41 (hereinafter referred to as an expansion / contraction pilot passage) 41 of the expansion / contraction pilot valve 19.
A branch hydraulic passage 10 a is connected to the unload passage 10 upstream of the switching valves 2 to 7. This branch hydraulic passage 10a is branched into three, and the ends of these branch passages are the pump port P of the winch control valve 31, the pump port P of the expansion / contraction control valve 32, and the pump of the undulation control valve 33, respectively. It is connected to port P.
[0030]
  A winch control valve 31 is interlocked with the winch switching valve 3, and the winch control valve 31 is configured as a three-port, three-position / mechanical switching valve. In the neutral position 31a of the winch control valve 31 when the winch switching valve 3 is in the neutral position 3a,Via the branch hydraulic passage 10aThe pump port P connected to the unload passage 10 is closed, and the tank port T connected to the tank passage 11 communicates with the load port R connected to the winch pilot passage 40. At the winding position 31b of the winch control valve 31 when the winch switching valve 3 is switched to the winding position 3b, the pump port P communicates with the load port R and the tank port T is closed. Further, at the lowering position 31c of the winch control valve 31 when the winch switching valve 3 is switched to the lowering position 3c, the pump port P is closed and the tank port T is in communication with the load port R.
[0031]
  An expansion / contraction control valve 32 is interlocked with the expansion / contraction switching valve 2, and the expansion / contraction control valve 32 is also configured as a three-port / three-position / mechanical switching valve. In the neutral position 32a of the expansion / contraction control valve 32 when the expansion / contraction switching valve 2 is in the neutral position 2a,Via the branch hydraulic passage 10aThe pump port P connected to the unload passage 10 is closed, and the tank port T connected to the tank passage 11 is a load port R connected to one port (hereinafter referred to as the left port) 34b of the shuttle valve 34. Communicating with The pump port P is closed and the tank port T is in communication with the load port R at the shortened position 32b of the expansion / contraction control valve 32 when the expansion / contraction switching valve 2 is switched to the shortened position 2b. Further, at the extended position 32c of the expansion / contraction control valve 32 when the expansion / contraction switching valve 2 is switched to the extended position 2c, the pump port P communicates with the load port R and the tank port T is closed.
[0032]
  A undulation control valve 33 is interlocked with the undulation switching valve 4, and the undulation control valve 33 is also configured as a 3-port, 3-position, mechanical switching valve. In the neutral position 33a of the undulation control valve 33 when the undulation switching valve 4 is in the neutral position 4a,Via the branch hydraulic passage 10aThe pump port P connected to the unload passage 10 is closed, and the tank port T connected to the tank passage 11 is a load port R connected to the other port (hereinafter referred to as the right port) 34c of the shuttle valve 34. Communicating with Further, at the rising position 33b of the raising and lowering control valve 33 when the raising / lowering switching valve 4 is switched to the rising position 4b, the pump port P communicates with the load port R and the tank port T is closed. Further, the pump port P is closed and the tank port T is in communication with the load port R at the fall position 33c of the rise and fall control valve 33 when the rise and fall switching valve 4 is switched to the fall position 4c.
[0033]
The operation and effect of the winch overwinding prevention device according to the above configuration will be described.
[0034]
  In FIG. 1, when winch winding is executed by switching the winch switching valve 3 to the switching position 3b, the winch control valve 31 is switched to the winding position 31b in conjunction with the operation of the winch switching valve 3. As a result, the unload passage 10 and the winch pilot passage 40 areBranch hydraulic passage 10a andThe communication state is established via the winding position 31b of the winch control valve 31, and the pressure in the unload passage 10 acts on the winch pilot valve 18 to switch from the closed position to the open position. For this reason, the third pilot passage 38 communicates with the tank passage 11 via the low pressure switching electromagnetic valve 17 and the winch pilot valve 18.
[0035]
When the hook 22 is wound up to a predetermined position near the tip of the boom 21 by the winding operation of the winch switching valve 3, the limit switch 23 detects this state and outputs a signal. Will open.
[0036]
When the solenoid valve 15 is opened, the first pilot passage 36 of the differential pressure valve 14 is in communication with the tank passage 11 by the third pilot passage 38, so that the first pilot passage 36 of the differential pressure valve 14 becomes tank pressure, The differential pressure valve 14 is opened. When the differential pressure valve 14 is opened, the unload passage 10 communicates with the tank passage 11 by the bypass passage 35, so that all the switching valves 2, 3, 4, 5, 6, 7 on the downstream side of the unload passage 10 are opened. No pressure oil is supplied, so that the operation of the actuator is stopped and overwinding is prevented.
[0037]
On the other hand, when the winch winds down the wire while the electromagnetic valve 15 is opened, that is, when the winch switching valve 3 is switched to the lowering position 3c, the winch control valve 31 interlocked therewith is moved to the lowering position 31c. Therefore, the winch pilot passage 40 is disconnected from the unload passage 10 and communicates with the tank passage 11. As a result, the winch pilot valve 18 is released from the pressure signal, so that it returns to the closed position and shuts off the third pilot passage 38 and the tank passage 11. Then, the first pilot passage 36 and the tank passage 11 of the differential pressure valve 14 are cut off, pressure is generated in the first pilot passage 36, and the differential pressure valve 14 is closed. When the differential pressure valve 14 is closed, pressure is also generated in the unload passage 10, so that pressure oil is supplied and the hydraulic actuator can execute an operation in which the winch winds the wire down.
[0038]
  Next, a description will be given of an operation in which the winch wire is effectively wound up, that is, a case where the boom is extended or the boom is raised by simultaneous operation or independent operation of the expansion / contraction switching valve 2 and the undulation switching valve 4..
When the expansion / contraction switching valve 2 and the undulation switching valve 4 are operated, that is, when the switching position of the expansion / contraction switching valve 2 is switched to the extended position 2c or the rising position 4b of the undulation switching valve 4, the expansion / contraction control valve 32 or The pump port P and the load port R of the hoisting control valve 33 are switched to the extended position 32c and the rising position 33b where the communication is established. As a result, the unload passage 10 isBranch hydraulic passage 10a andThe expansion control valve 32 communicates with the left port 34b of the shuttle valve 34 through the extended position 32c, or communicates with the right port 34c of the shuttle valve 34 through the rising position 33b of the hoisting control valve 33. At this time, the higher pressure of the pressure acting on the right port 34c or the left port 34b is guided to the secondary port 34a of the shuttle valve 34. When the raising operation is performed simultaneously or independently, the pressure in the unload passage 10 acts on the expansion / contraction undulating pilot valve 19 to switch from the closed position to the open position. to thisThanThe fourth pilot passage 39 communicates with the tank passage 11 via the expansion / contraction raising / lowering pilot valve 19.
[0039]
When the hook 22 is wound up to a predetermined position near the tip of the boom 21 by operating the expansion / contraction switching valve 2 and the undulation switching valve 4 alone or simultaneously, the limit switch 23 detects this state. In order to output a signal, the solenoid valve 15 is opened.
[0040]
When the solenoid valve 15 is opened, the first pilot passage 36 of the differential pressure valve 14 is in communication with the tank passage 11 by the fourth pilot passage 39, so that the first pilot passage 36 of the differential pressure valve 14 becomes tank pressure, The differential pressure valve 14 is opened. When the differential pressure valve 14 is opened, the unload passage 10 communicates with the tank passage 11 via the bypass passage 35, so that no pressure oil is supplied to all the switching valves 2, 3, 4, 5, 6, 7. Therefore, the operation of the hydraulic actuator is stopped and overwinding is prevented.
[0041]
On the other hand, an operation in which the winch winds the wire while the electromagnetic valve 15 is opened, that is, an operation to switch the expansion / contraction switching valve 2 to the shortened position 2b or to switch the undulation switching valve 4 to the collapsed position 4c is performed. Then, the telescopic control valve 32 and the hoisting control valve 33 interlocked with these switches to the shortened position 32b and the fall position 33c, so that the telescopic hoisting pilot passage 41 is cut off from the unloading passage 10 and the tank passage 11 Communicate. As a result, the expansion / contraction undulating pilot valve 19 is released from the pressure signal, so that it returns to the closed position and shuts off the fourth pilot passage 39 and the tank passage 11. Then, the first pilot passage 36 of the differential pressure valve 14 is blocked, pressure is generated in the first pilot passage 36, and the differential pressure valve 14 is closed. When the differential pressure valve 14 is closed, pressure is also generated in the unload passage 10, so that pressure oil is also supplied to each hydraulic actuator in which each switching valve 2, 4 is operated, and the winch winds the wire down the hydraulic actuator. Such an operation will be executed.
[0042]
When the hook-in operation for storing the winch hook 22 in the horizontal direction is performed as shown in FIG. 2, the wire needs to be wound up beyond the overwinding prevention position. In the present embodiment, when the hook-in operation is executed, the wire can be gently wound up beyond the overwinding prevention position. Next, the winding operation beyond the overwinding prevention position during the hook-in operation will be described.
[0043]
When a switch (not shown) for performing a hook-in operation is turned on with the solenoid valve 15 opened, the low pressure switching solenoid valve 17 is switched to the closed side. Further, as the winch switching valve 3 is switched to the hoisting position 3b, the winch control valve 31 is switched to the hoisting position 31b, and the pilot pressure is applied to the winch pilot valve 18, thereby the winch pilot. The valve 18 opens.
[0044]
In this state, when the pressure in the third pilot passage 38 of the differential pressure valve 14 becomes equal to or higher than the set pressure of the low pressure relief valve 12, the low pressure relief valve 12 is opened. When the low-pressure relief valve 12 is opened, the pressure in the unload passage 10 is maintained at the set pressure of the low-pressure relief valve 12, so that the winch-use pressure is supplied from the unload passage 10 via the winding position 3b of the winch switching valve 3. The pressure oil supplied to the hydraulic actuator becomes the set pressure of the low pressure relief valve 12. Accordingly, the winch hydraulic actuator is in a state of winding up the winch wire by a gentle operation. That is, the winch hydraulic actuator performs the hook-in operation gradually.
[0045]
FIG. 3 is a circuit diagram showing a winch overwinding preventing apparatus according to a second embodiment of the present invention.
[0046]
The present embodiment is different from the first embodiment in that the low-pressure switching electromagnetic valve 17 is omitted. The hook-in operation in this case is executed as follows. When the winch switching valve 3 is switched to the winding position 3b with the solenoid valve 15 opened, the pilot pressure is applied to the winch pilot valve 18 when the winch control valve 31 is switched to the winding position 31b. Therefore, the winch pilot valve 18 is opened. In this state, when the pressure in the third pilot passage 38 of the differential pressure valve 14 becomes equal to or higher than the set pressure of the low pressure relief valve 12, the low pressure relief valve 12 opens, so that the pressure in the unload passage 10 becomes lower than that of the low pressure relief valve 12. The pressure is lowered to the set pressure and supplied to the winch actuator via the winding position 3 b of the winch switching valve 3. As a result, the winch actuator winds the wire, but since the pressure is low, the winding operation becomes gentle. That is, a hook-in operation is realized. In the state where the crane is lifting the load, when the hook is turned to the overwinding position by winding the winch, the pressure in the unload passage 10 is reduced to the set pressure of the low pressure relief valve 12, so that the winch is practically used. Is not wound up beyond the overwinding position.
[0047]
FIG. 4 is a circuit diagram showing a winch overwinding preventing apparatus according to Embodiment 3 of the present invention.
[0048]
This embodiment is different from the first embodiment in that the pump port P of the winch control valve 31 is connected to the hydraulic actuator passage A2, and the pump port P of the expansion / contraction control valve 32 is connected to the hydraulic actuator passage B1, thereby The pump port P of the control valve 33 is connected to the hydraulic actuator passage A3.
[0049]
According to this embodiment, there exists an advantage that the position detection of the switching valves 2, 3, and 4 can be performed. For example, when the winch switching valve 3 is switched to the winding position 3b, the pressure of the unload passage 10 is applied to the hydraulic actuator passage A2, and this pressure is applied to the pump port P of the winch control valve 31. At this time, since the winch control valve 31 is switched to the winding position 31b, the pressure applied to the pump port P is applied as a pilot pressure to the winch pilot valve 18 via the winch control valve 31. On the other hand, when the winch switching valve 3 is switched to the winding position 3b, the pressure of the unload passage 10 is applied to the hydraulic actuator passage B2, and no pressure is applied to the hydraulic actuator passage A2, so the winch pilot valve 18 No pilot pressure is applied through the pump port P of the winch control valve 31. That is, the position of the winch switching valve 3 is detected.
[0050]
Also in this embodiment, the low pressure switching electromagnetic valve 17 can be omitted.
[0051]
FIG. 5 is a circuit diagram showing a winch overwinding preventing apparatus according to a fourth embodiment of the present invention.
[0052]
This embodiment is different from the first embodiment in that the electromagnetic valve 15A is not connected to the pilot passage 36 but is interposed in the branch hydraulic passage 10a of the unload passage 10, and the electromagnetic valve 15A has three ports, It is a point comprised as a 2 position and electromagnetic switching valve.
[0053]
According to the present embodiment, the pressure in the winch pilot passage 40 and the expansion / contraction undulation pilot passage 41 is increased by the leakage of the electromagnetic valve 15A that is not in communication, so that the winch pilot valve 18 and the expansion / contraction undulation pilot valve 19 are used. Can be prevented from opening.
[0054]
Also in this embodiment, the low pressure switching electromagnetic valve 17 can be omitted.
[0055]
【The invention's effect】
  As described above, according to the present invention, it is possible to detect the operation of the switching valve in the direction in which the hook of the winch approaches the tip of the boom without using an electric means, thereby preventing the winch from being overwound. Therefore, the detection position of the switch mounted for each switching valveOpen positionIt is possible to omit a great amount of cost and time such as adjustment to match the environment, environmental measures for mounting the switch, and processing of the wiring. As a result, it is possible to improve productivity and reduce cost.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a winch overwinding preventing apparatus according to an embodiment of the present invention.
FIG. 2 is a side view showing an appearance of a truck crane.
FIG. 3 is a circuit diagram showing a winch overwinding preventing apparatus according to a second embodiment of the present invention.
FIG. 4 is a circuit diagram showing a winch overwinding preventing apparatus according to a third embodiment of the present invention.
FIG. 5 is a circuit diagram showing an overwinding prevention device for a winch that is Embodiment 4 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Operation apparatus for driving a truck crane, 2 ... Boom expansion / contraction switching valve (extension / contraction switching valve), 2a ... Neutral position, 2b ... Shortening position, 2c ... Extension position, 3 ... Winch hoisting / lowering switching valve ( Winch switching valve), 3a ... neutral position, 3b ... winding position, 3c ... lowering position, 4 ... boom raising / lowering switching valve (raising / lowering switching valve), 4a ... neutral position, 4b ... rising position, 4c ... fall position, 5 ... Boom right turn left turn switching valve (turn switch valve), 5b ... Left turn position, 5c ... Right turn position, 6, 7 ... Outrigger up / down switching valve (outrigger switching valve), 6b, 7b ... Upward movement position, 6c, 7c ... Downward movement position, 8 ... Pump, 9 ... Tank, 10 ... Unload passage, 10a ... Branch hydraulic passage, 11 ... Tank passage, A1-A6, B1-B6 ... Hydraulic actuator passage, 12 ... Low pressure 14 ... Differential pressure valve, 14a ... Pilot port, 15, 15A ... Solenoid valve, 16 ... Relief valve for high pressure, 17 ... Low pressure switching solenoid valve, 18 ... Pilot valve for winch, 19 ... Pilot valve for expansion and contraction, DESCRIPTION OF SYMBOLS 21 ... Boom, 22 ... Suspension hook, 23 ... Limit switch, 31 ... Control valve for winches, 31a ... Neutral position, 31b ... Winding position, 31c ... Lowering position, 32 ... Control valve for expansion / contraction, 32a ... Neutral position, 32b ... shortened position, 32c ... extended position, 33 ... hoisting control valve, 33a ... neutral position, 33b ... rising position, 33c ... tilted position, 34 ... shuttle valve, 34a ... secondary port, 34b ... left port, 34c ... right port, 35 ... bypass passage, 36 ... first pilot passage, 37 ... second pilot passage, 38 ... third pilot passage, 39 ... fourth Pilots passage 40 ... pilot passage of the pilot valve winch (pilot passage winch), 41 ... elastic pilot passage undulations pilot valve (telescopic hoist pilot passage).

Claims (2)

A hydraulic pressure source, an unload passage connected to the hydraulic pressure source, a tank passage connected from the unload passage to the tank, and a winch connected between the unload passage and the tank passage according to a switching operation. A winch switching valve for supplying and discharging pressure oil to and from the winch, a boom expansion and contraction switching valve for supplying and discharging pressure oil to and from the actuator for extending and retracting the boom, and pressure oil to the actuator for raising and lowering the boom. A boom raising / lowering switching valve for supplying and discharging, a bypass passage connecting the upstream side of the winch switching valve of the unload passage to the tank passage, a normally closed differential pressure valve interposed in the bypass passage, The pilot valve of the differential pressure valve interposed between the differential pressure valve and the tank passage by controlling the opening and closing of the pressure valve, and the winch winds up to a predetermined position. A detecting means for outputting a detected signal that, in the over-winding prevention apparatus winch and an electromagnetic valve which is interposed in the pilot passage opens and the differential pressure valve by a signal of the detection means,
A winch control valve linked to the winch switching valve, and a branch hydraulic passage branched from the unload passage and supplying and discharging pressure oil to and from the winch control valve,
The branch hydraulic passage is divided into three branches, and the respective leading ends of these branch paths detect the pump port of the winch control valve that detects the operating direction of the winch switching valve and the operating direction of the telescopic switching valve. Connected to a pump port of the control valve for expansion and contraction, and a pump port of the control valve for undulation detecting the operation direction of the undulation switching valve,
A winch pilot valve whose opening and closing is controlled by pressure oil discharged from the winch control valve is interposed in the pilot passage of the differential pressure valve,
A winch overwinding prevention device characterized by that.   2. The winch overwinding prevention device according to claim 1, wherein a low pressure relief valve and a normally open low pressure switching electromagnetic valve are provided in parallel in the pilot passage of the differential pressure valve.

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