JPH0654687U - Hook storage device for vehicle-mounted crane - Google Patents

Abstract

(57) [Summary] [Purpose] Damage to the hook abutment part due to erroneous operation when the hook is stored in contact with the boom tip and the horizontal boom with the minimum winding length is extended or stood up for loading work. prevent. [Configuration] In the state of FIG. 1 in which the overwinding detection switch 12 is closed, the unload valve 22 whose vent ports are closed by the electromagnetic opening / closing valves 23 and 24 is closed, and the high pressure relief valve 21 limits the hydraulic pressure during cargo handling work. When the overwinding detection switch is opened and the relay 28 is closed to the B contact side, the solenoid 31 is switched to the NO contact side because the switch 31 is switched to the NO contact side in conjunction with the winding control by the direction switching valve 16. Open the unload valve,
Stop the winding drum. When the hook storage switch 33 is closed at the same time as this hoisting control, only the electromagnetic opening / closing valve 23 is closed and the unload valve is controlled by the low pressure relief valve 25 to wind and store the hook at low pressure. If the boom storing the hook is erroneously extended or erected, the switch 30 or 32 opens in conjunction with this, and the unload valve opens to prevent the damage.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hook storage device applied to an on-vehicle crane such as a truck-mounted crane.

[0002]

[Prior art]

 A low pressure relief valve is connected to the pump discharge port of the crane hydraulic circuit where the conventional hydraulic pressure is limited by the high pressure relief valve, or to the hoisting cylinder hydraulic oil passage, and the hoisting drive hydraulic pressure of the hoisting cylinder is increased during normal cargo handling work. In addition, the high pressure relief valve is unloaded by the signal generated by the overwind detection switch when overwinding, and the hook is hoisted up and stored in the overwinding state as shown in Japanese Utility Model Publication No. 3-82389. In this case, the fact that the working oil pressure of the winding cylinder is limited at least by the low-pressure relief valve that is activated by the simultaneous operation of the winding cylinder and the hook storage switch is disclosed in Japanese Utility Model Publication No. 4-51493. Has been done.

[0003]

[Problems to be solved by the device]

 In this conventional technique, in the horizontal position of the retractable boom that stores the hook, that is, in the road traveling posture, the winding line between the winding drum and the pulley at the tip of the boom is tensioned in a substantially parallel arrangement with the boom. When moving the telescopic boom from the on-road posture to the cargo handling posture, the hook storage switch was closed first, and the winding cylinder control direction switching valve was switched to the lowering side to eliminate the over-winding condition of the hook. Afterwards, the boom must be extended or raised, but when operating this directional control valve for winding cylinder control to the lowering side, the directional control valve for controlling the boom telescopic cylinder or the delicate cylinder is mistakenly extended or extended. When it is operated to the upright side, as the boom extends or stands up, the distance between the winding drum and the pulley at the tip of the boom increases. Which may lead to breakage of the contact engaging portion or the like of the. This is because the pressure receiving area of the boom telescopic cylinder and the delicate cylinder is set so that the boom can be extended and stood up while the load is suspended.The present invention aims to prevent damage due to this erroneous operation. .

[0004]

[Means for Solving the Problems]

 According to the present invention, a high pressure relief valve and an unload valve are connected in parallel between a hydraulic pump discharge port and a tank of a crane hydraulic circuit for operating the hoisting drum and other parts of the crane, and the vent port of the unload valve is connected. In a vehicle-mounted crane with a normally open first electromagnetic on-off valve connected to the tank, a low-pressure relief valve was connected to the vent port of the unload valve via a normally open second electromagnetic on-off valve to prevent overwinding. Between the normally-closed contact B and the normally-open contact A of the relay, which are made conductive by the signal generated by the detection switch, the delicate cylinder, the winding cylinder drive hydraulic motor, and the boom telescopic cylinder are respectively provided on the overwinding promotion side. The NC contact sides of three microswitches that can be switched to the NO contact side only when controlled are connected in series, and the operation solenoids of the first and second solenoid on-off valves are connected to the normally open side contact A of the relay. A hook storage switch is connected between the NO contact of the micro switch and the operating solenoid of the first solenoid opening / closing valve, which is connected to the column and is interlocked with the control of the winding cylinder driving hydraulic motor, and the hook storage switch is electrically connected. At this time, means for cutting off the power supply to the operating solenoid of the second solenoid opening / closing valve is provided.

[0005]

【Example】

 As shown in FIG. 2, for example, an on-vehicle crane includes hydraulically actuated outriggers 1 and 1 that are detachably mounted on a vehicle body frame S of a truck or other vehicle, and telescopic telescopic beams 2 of the both outriggers. A post 3 rotatably mounted on a base cylinder by a swivel hydraulic motor, a telescopic telescopic boom 6 pivotally supported by a derrick cylinder 4 on a top end of the post 3 by a foot pin 5, and the telescopic boom. 6 includes a boom telescopic cylinder built in 6 and a winding drum 7 mounted in the post 3 so as to be driven by a hydraulic motor. A winding line 8 fed from the winding drum 7 is a gooseneck portion 6a at the tip of the telescopic boom. The ends of the hoisting cords are fastened to the gooseneck so that a hook 11 having two block pulleys 10 can be suspended and supported via a plurality of pulleys 9 attached to the gooseneck. To have. Therefore, at the horizontal position of the telescopic boom 6 in which the upper end of the hook 11 is stowed in the gooseneck portion 6a, the distance between the winding drum 7 and the pulley 9 at the tip of the boom is substantially minimum.

Reference numeral 12 denotes an overwinding detection switch attached to the tip of the telescopic boom 6. At the lower end of the operation rope 13 of the overwinding detection switch 12, one of the winding ropes 8 a for suspending and supporting the hook 11 is provided. A weight 14 fitted so as to be vertically movable is suspended and supported. For this reason, the switch 12 is closed while the weight of the weight 14 is acting on the actuation rope 13, but when the hook 11 lifts the weight 14, the switch 12 is opened.

FIG. 1 shows a hydraulic and electric circuit diagram for operating a crane according to an embodiment of the present invention. The crane hydraulic circuit controls a direction switching valve 16 for controlling a drive hydraulic motor 15 of a winding cylinder 7 and a boom telescopic cylinder. The directional control valve 17 for controlling the derrick cylinder 4, the directional control valve for controlling the swing hydraulic motor, and the like are provided between the directional control valve 17 and the directional control valve 17. As in the prior art, it is connected to the discharge port of the hydraulic pump 19 in series. Reference numeral 20 denotes an oil passage from the direction switching valve 17 to the boom expansion and contraction cylinder. The operating lever of each direction switching valve is rotated in a horizontal plane so that the post 3 can be operated from either left or right of the body frame. Are placed side by side on both sides of the.

A high pressure relief valve 21 and an unload valve 22 are connected in parallel between the discharge port of the hydraulic pump 19 and the tank T, and a high pressure relief valve 21 and an unload valve 22 are normally connected between the vent port 22 a of the unload valve 22 and the tank T. The open-type first and second electromagnetic on-off valves 23 and 24 are connected in parallel, and a small capacity low pressure relief valve 25 is inserted between the second electromagnetic on-off valve 24 and the tank T. The illustrated first and second electromagnetic on-off valves are closed because their operating solenoids are in a conductive state.

The electric circuit for operating the crane is provided with a switch 27 that is closed in conjunction with the power take-out device PTO of the automobile engine capable of driving the hydraulic pump 19 when the power take-out device PTO is switched to the power take-out position. A relay 28 that connects and disconnects the electromagnetic coil C by the overwinding detection switch is connected to the circuit that connects the overwinding detection switch 12 to the power source 26 via the normally closed contact of the relay 28. A rectifier (diode) 29 and NC contact sides of the three micro switches 30, 31, 32 are connected in series between B and the normally open side contact A, and at the normally open side contact A of the relay, The operation circuits 35 and 36 of the operation solenoids of the first and second electromagnetic on-off valves 23 and 24 are connected in parallel.

The micro switch 30 is attached to the directional control valve so that it can be switched to the NO contact side only when the operating lever of the directional control valve for controlling the delicate cylinder 4 is operated to the boom upright position, that is, the overwinding promotion side. To be Therefore, when the operation lever is operated to the neutral position or the boom fall position, the micro switch 30 returns to the NC contact side shown in the figure by its own return spring elasticity.

The micro switch 31 is switched to the NO contact side only when the operating lever of the direction switching valve 16 for controlling the winding cylinder driving hydraulic motor 15 is operated to the hoisting position, that is, the overwinding promotion side, and the operating lever is switched. When is operated to the neutral position or the unwinding position, the micro switch 31 similarly returns to the NC contact side by spring return.

The micro switch 32 is switched to the NO contact side only when the operation lever of the direction switching valve 17 for controlling the boom telescopic cylinder is operated to the boom extension position, that is, the overwinding promotion side, and the operation lever is moved to the neutral position or the neutral position. When operated to the boom retracted position, the micro switch 32 returns to the NC contact side by spring.

In addition, between the NO contact of the micro switch 31 and the operating solenoid of the first solenoid on-off valve 23, which are interlocked with the control of the winding cylinder driving hydraulic motor 15, the hook storing switches (pushing switches) provided on both sides of the in-vehicle crane are respectively arranged. The button switches 33, 33 are connected in parallel, and the rectifier (diode) 34 for shutting off the energization of the operating solenoid of the second electromagnetic opening / closing valve 24 when the hook storing switch 33 is conducting is connected to the first electromagnetic opening / closing switch. The valve 23 is inserted in the middle of the operation circuit 35. In the figure, reference numeral 37 denotes an overwind alarm (buzzer) connected in parallel with a rectifier 29 or the like to a normally closed contact B of a relay 28. The rectifier 29 is an overwind alarm when the circuit is in the position shown in FIG. Prevent the operation of the device 37.

The present invention has the above-mentioned structure, and in the normal cargo handling work state in which the hook 11 is located below the weight 14 as shown in FIG. 2, the overwinding detection switch 12 is closed and the power take-off device PTO is used. Is driving the hydraulic pump 19 and closing the switch 27, the hydraulic and electric circuits for operating the crane are in the state shown in FIG. 1, and the hydraulic fluid discharged from the hydraulic pump is in the neutral position at each directional control valve. It is discharged to the tank T through the bypass 18 such as 16 and 17, and the pump is operated without load. Further, since the electromagnetic coil C of the relay 28 is conducted through the overwinding detection switch 12 and the relay contact is switched to the normally open contact A, the first and second electromagnetic on-off valves 23 and 24 are closed. Therefore, the unload valve 22 is maintained in the closed state, and the working hydraulic pressure of the crane hydraulic circuit is limited by the high pressure relief valve 21 so that cargo handling work can be performed.

Therefore, the direction switching valve 16 is switched to the winding upper side to drive the drive hydraulic motor 15 of the winding cylinder 7 in the winding direction (the direction of the arrow), so that the hook 11 that suspends the load is lifted and the hook is heavy. When the weight 14 is lifted, the overwinding detection switch 12 is opened to make the relay 28 non-conductive, so that the relay contact is returned to the normally closed contact B by the return spring elasticity to operate the overwinding alarm device 37. . On the other hand, the micro switch 31 is switched to the NO contact side in conjunction with the hoisting control of the winding cylinder 7 and the hook storing switch 33 is also opened. Therefore, at the time of returning to the normally closed contact B of the relay 28 described above. The first and second electromagnetic on-off valves 23, 24 are in the open position with their operating solenoids non-conductive, and the first electromagnetic on-off valve 23 communicates the vent port of the unload valve 22 with the tank T. Then, the unloading valve is opened to discharge the discharge oil of the hydraulic pump 19 to the tank to stop the driving of the winding cylinder 7, and the winding cylinder is mounted on the counter of the hydraulic oil motor 15 on both sides thereof. Reverse rotation is stopped by a tabalance valve (not shown) to stop.

When the hook 11 is stored from this over-wound state, the directional switching valve 16 is operated to the upper side of the winding and the hook storage switch 33 is closed, so that the first solenoid valve 23 has its operating solenoid connected. However, since the rectifier 34 shuts off the current flowing from the hook storage switch 33 to the circuits 35 and 36 in sequence, the second solenoid on-off valve 24 is spring-returned to the open position, so that the set pressure of the low-pressure relief valve 25 is unloaded. Since the pressure of the vent port 22a of the valve is limited and the unload valve 22 operates as a low pressure relief valve to drive the winding cylinder at low pressure, the upper end of the hook 11 to be lifted collides with the end of the boom. However, there is no risk of damaging the abutting engagement portions of the two, and if the directional control valve 16 is returned to the neutral position, the hook will stop at the retracted position.

In this way, in the hook retracted state where the upper end of the hook is brought into abutting engagement with the boom tip, that is, in the tensioned state of the winding line 8, the boom expansion / contraction cylinder or the derivation cylinder direction switching valve 17 is tried to extend or stand up the boom 6. Etc. are operated to the overwinding promotion side (boom extension or standing side), the micro switch 30 or 32 is switched to the NO contact side, and the operation circuits 35 and 36 of the first and second solenoid on-off valves are deactivated. Because of the continuity, the unload valve 22 opens to prevent the boom from extending or standing up.

Therefore, when the hook is in the retracted state, the winding drum 7 must be fed out from the winding drum 7 until the hook 11 is lowered below the operating weight 14 of the overwinding detection switch 12. The distance between the boom and the pulley 9 at the tip of the boom increases and the boom cannot be extended or erected (actuation on the excessive winding side). Therefore, when the winding cylinder control direction switching valve 16 is operated to the unwinding side in order to unwind the winding wire 8 from the winding cylinder 7, it is erroneously mistaken for the overwinding promotion of the direction switching valve 17 of the boom telescopic cylinder or the delicate cylinder. Even if it is operated to the side, the unloading valve 22 is opened to make it impossible to extend or stand up the boom as described above, so that there is no possibility of damaging the abutting engagement portion between the boom tip and the hook.

The embodiment in which the rectifiers 29 and 34 for preventing the reverse flow are provided in the electric circuit for operating the crane has been described above, but instead of providing both rectifiers, the switch 27 is provided with the first rectifier as shown in FIG. The second relay 38 for operating the overwind alarm 37 connected in parallel with the relay 28 and the NO contact of the micro switch 31 connected in parallel with the hook storing switch 33 to operate the second solenoid opening / closing valve 24. A third relay 39 for controlling the opening and closing of the circuit 36 may be provided. In FIG. 3, parts having the same reference numerals as those of FIG. 1 are corresponding parts.

According to the configuration of FIG. 3, if the overwinding detection switch 12 is opened due to the overwinding state during the cargo handling work, the second relay 38 is switched to the normally closed contact B side to turn on the overwinding alarm device 37. When the micro-switch 31 is switched to the NO contact side by operating and winding the winding cylinder in the over-winding state, the third relay 39 becomes conductive and the contact B is opened, so that the hook storing switch 33 It is clear from the figure that the current flowing back from the switch 33 to the circuits 35 and 36 is shut off even if the switch is closed.

[0021]

[Effect of device]

 According to the present invention, the hook is retracted and the substantially horizontal telescopic boom with the minimum length of the rope is moved to the loading work posture, so that the winding cylinder is controlled to be lowered so as to eliminate the overwinding state. Even if the boom telescopic cylinder or the derick cylinder is accidentally controlled to the overwinding promotion side, damage to the abutting engagement part between the boom tip and the hook can be prevented, and the working oil pressure is limited by the high pressure relief valve. The automatic stop of the winding cylinder when the hook is overwound during the cargo handling operation described above, and the low hydraulic operation of the winding cylinder drive hydraulic motor when the hook is hung and stored for traveling on the road, is the same as before. It has the effect that it can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a hydraulic pressure and electric circuit for operating a crane.

FIG. 2 is a front view showing the outline of an on-vehicle crane.

FIG. 3 is a diagram showing another embodiment of the electric circuit for operating the crane.

[Explanation of symbols]

 4 Delicate cylinder 6 Telescopic boom 7 Hoisting drum 8 Hoisting rope 11 Fuchs 12 Overwinding detection switch 15 Hoisting cylinder drive hydraulic motor 19 Hydraulic pump 21 High pressure relief valve 22 Unload valve 23 1st solenoid opening / closing valve 24 2nd solenoid opening / closing valve 25 Low pressure Relief valve 28 Relay 30 Micro switch 31 Micro switch linked to winding cylinder control 32 Micro switch 33 Hook storage switch 34 Rectifier

Claims (1)

[Scope of utility model registration request] 1. A high pressure relief valve and an unload valve are connected in parallel between a hydraulic pump discharge port and a tank of a crane hydraulic circuit for operating each of the crane and other parts of the crane, and the vent of the unload valve is connected. In a vehicle-mounted crane in which a normally open first electromagnetic on-off valve is connected between the port and the tank, a low pressure relief valve is connected to the vent port of the unload valve via the normally open second electromagnetic on-off valve, Normally closed contact B of the relay, which is made conductive by the signal generated by the winding detection switch.
NC of three microswitches that can be switched to the NO contact side only when the delicate cylinder, the winding cylinder driving hydraulic motor, and the boom telescopic cylinder are controlled to the overwinding promotion side between the normal opening side contact A and the normally open side contact A, respectively. The contact side is connected in series, the actuating solenoids of the first and second electromagnetic on-off valves are connected in parallel to the normally open side contact A of the relay, and the micro is interlocked with the control of the winding cylinder driving hydraulic motor. Switch NO
A hook storing switch is connected between the contact and the operating solenoid of the first electromagnetic opening / closing valve, and means is provided for cutting off energization to the operating solenoid of the second electromagnetic opening / closing valve when the hook storing switch is conductive. A hook storage device for an in-vehicle crane, which is characterized in that