JPH036116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a winding drum device such as a truck crane, and in particular to an engaging cylinder of a clutch which is constantly energized to disconnect.
The present invention relates to a winding drum device for a clutch which is provided with a winding drum clutch control circuit including a clutch control valve for selectively connecting the clutch engaging cylinder to either a hydraulic power source or a tank, and a winding drum brake that can be manually operated.

With such a device, a suspended load below the free-fall limit load (a fraction of the normal rated load or permissible lifting load) can be freely lowered by the action of gravity, but if the detected load of the suspended load reaches the free-fall limit load. If a safety device is provided to prevent the free-falling operation when the free-falling operation occurs, the free-falling limit load can be increased compared to the conventional method. This safety device is designed to automatically drive the hoisting drum when the detected load of the hoisting load reaches the free-fall limit load when the hoisting drum is used to lift a hoisted load from its original position at a high place to the free-fall starting position. If a device is installed to automatically stop the load, it will stop when the detected load of the suspended load exceeds the free-fall limit load due to lateral loads such as gusts of wind or inertia caused by the rotation of the crane swivel platform acting on the suspended load during free descent. Safety devices will no longer function. To avoid this, when the detected load of the suspended load reaches the free-fall limit load at the free-fall start position, the brake release cylinder is directly connected to the tank and the drum brake is tightened to prevent free-fall. The suspended load at the free fall start position cannot be lowered to the original position by the hoisting drum.

The present invention addresses this problem by providing a detection device that can be activated during free fall to provide a signal when the suspended load reaches the free fall limit load;
The present invention is characterized in that an oil passage switching device is provided in the winding drum clutch control circuit to connect the clutch engaging cylinder at the clutch disengaged position only to the hydraulic power source in response to a signal generated by the detection device.

An embodiment of the present invention will be described below with reference to FIG. 1 is a winding drum driven by a hydraulic motor; 2 is a clutch engagement cylinder for a winding drum clutch which is installed between the winding drum 1 and the drive hydraulic motor shaft and is constantly biased to disconnect by a spring 3; 4 is an oil cylinder; A manual switching clutch control valve selectively connects the clutch engaging cylinder 2 to either the hydraulic source (accumulator) 6 or the tank T via the passage 5; 7 indicates a control circuit for the hydraulic motor driving the winding drum 1; When the control circuit 7 operates the three-position directional switching valve to drive the drum drive hydraulic motor in either the forward or reverse direction, it fills the accumulator 6 with hydraulic pressure via the oil passage 8 and the check valve 9.

The illustrated winding barrel brake has a spring 1 for simplification of explanation.
A brake cylinder 11 that tightens the brake that is always released and activated by 0 is provided, and a pedal-operated master cylinder 13 that is connected to the brake cylinder 11 via an oil passage 12. and the opposite side oil chamber 15 which is always in communication with the tank T are connected by a check valve 16 attached to a piston, and the master cylinder 13 is always urged to return to the brake release position shown in the figure by a spring 17, A removable stopper device 19 capable of restraining the brake pedal 18 in the brake tightening position is installed in the clutch driver's cab, but the structure of the drum brake is not limited to this, and the brake can be constantly tightened. A brake control circuit is provided for automatically supplying or discharging hydraulic pressure to the releasing brake cylinder in accordance with driving or stopping of the winding drum, and a master cylinder of the brake cylinder, which can be manually controlled, is connected to the brake control circuit. You may insert it into

The manual switching clutch control valve 4 has a pilot operation part 20 that can switch the clutch engaging cylinder 2 located at the upper position in the figure (clutch disengaged position) to the lower position shown in the figure (clutch engaged position) which connects it to the hydraulic power source 6.
and an electromagnetic switching valve 22 which is always energized to return to a position where the pilot operating section is communicated with the tank T, and which is switched to a position where the pilot operating section 20 is connected to the hydraulic power source 6 when the solenoid 21 is conductive. , when the pilot operating section 20 is in communication with the tank T, the clutch control valve 4 can be switched freely.

Reference numeral 23 denotes a crane overload prevention detection device, which includes a memory 24 that outputs the permissible lifting load (rated load) according to the elevation, expansion and contraction, etc. of the telescopic boom, and a detector 25 that detects the actual lifting load. When the two-pole changeover switches 26 and 27 connected to the output sides of the memory 24 and the detector 25 are closed to the contact A side,
The outputs of the memory device 24 and the detector 25 are connected to conductive wires 28 and 28, respectively.
29 to a comparator (not shown) which issues a signal if the two outputs are equal. As in the prior art, the signal generated by this comparator operates a device for stopping the operation of the crane operating equipment in the direction of increasing the crane overturning moment.

When the changeover switches 26 and 27 are closed to the contact B side, the output of the memory 24 is reduced by a percentage to the output corresponding to the free fall limit load.
The signal is then transmitted to the comparator 31 along with the output of the detector 25. The comparator 31 issues a signal when the output of the detector 25 becomes equal to or greater than the output of the calculator 30, turns on the solenoid 21, and switches the switching valve 22 to the lower position in the figure.

Although not shown, the detection device 23 is equipped with a calculator that calculates the product of the mass of the suspended load and its free fall speed or the square of the hoisting drum rotation speed, and the output of the calculator is There should be an alarm (buzzer) that goes off when the temperature reaches or exceeds a certain value that may cause damage.

In the above configuration, with the clutch control valve 4 in the lower position shown in the figure, the clutch engagement cylinder 2 is connected to the hydraulic source 6.
The winding trunk clutch is engaged by connecting to the
It is clear that if the changeover switches 26 and 27 are closed to the contact A side, normal cargo handling work, that is, lifting or hanging of the cargo using the winding drum, can be performed.

Also, in order to freely lower the load, a changeover switch 26,
27 to the contact B side as shown, then close the winding drum 1.
After controlling each part of the crane to lift and stop the suspended load at the original position to the free-fall starting position, when switching the clutch control valve 4 to the upper position in the diagram (clutch disconnection position) to disconnect the clutch, the suspended load load is If the load is below the free-fall limit load and the comparator 31 does not issue a signal, the clutch control valve 4 can be switched to allow the suspended load to freely fall under the action of gravity. If the comparator 31 issues a signal, the switching valve 22 is switched to the lower position in the figure and the pilot operating section 20
Since pilot pressure is supplied from the hydraulic source 6 to
The clutch control valve 4 cannot be switched to the clutch disengaged position, and the drum clutch remains engaged, preventing free descent of the suspended load.

If a lateral load due to a gust of wind or the like acts on the suspended load during free descent and the load detected by the detector 25 reaches the free descent limit load, the comparator 31 issues a signal and the clutch control valve 4 is switched to the lower position shown, which engages the hoisting drum clutch, thereby automatically stopping the free descent of the suspended load. When the above-mentioned alarm (buzzer) is activated during the free descent of a suspended load, the master cylinder 13 operates the winding barrel brake to a certain extent to reduce the free descent speed until the alarm stops operating. Of course, it is necessary to slow down the speed.

When the suspended load stops during free descent, the clutch control valve 4 may be switched to the clutch disconnection position to allow the suspended load to freely descend again, depending on whether the above-mentioned lateral load generation phenomenon disappears or continues. The hoisted load can also be suspended by driving the winding drum 1.

Although one embodiment has been described above, the oil passage switching device is such that the clutch control valve 4 is provided with a solenoid operating section instead of the pilot operating section 20, and the clutch control valve is directly switched by the signal generated by the comparator 31. Alternatively, as shown in FIG. An electromagnetic switching valve 32 is always activated to return to the upper position, and is switched to the lower position to directly connect the clutch engagement cylinder 2 to the hydraulic power source 6 via the oil passage 34 when receiving a signal from the comparator 31. May be inserted. Reference numeral 33 indicates a solenoid operating portion of the electromagnetic switching valve 32, and in the figure, members with the same reference numerals as in FIG. 1 are corresponding members.

According to the present invention, when the detected load of the suspended load reaches the free fall limit load at the start of its free fall, of course,
Even when some kind of lateral load acts during free-fall and the free-fall limit load is reached, the clutch control valve is switched to the position where the hoisting trunk clutch is engaged, thereby preventing the suspended load from freely falling. In addition, it is possible to start free descent again in response to the disappearance or persistence of the lateral load, or to lift or suspend the suspended load by the hoisting drum, and during the free descent of the suspended load, Since a certain amount of braking force is normally provided by the drum brake, damage to the drum clutch can be prevented even if the clutch is used to prevent free descent.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the present invention, and FIG. 2 is a circuit diagram of main parts of another embodiment. 1... Winding drum, 2... Clutch engagement cylinder, 4
...Clutch control valve, 6...Hydraulic pressure source, 7...Control circuit for the drum drive hydraulic motor, 11...Brake cylinder, 13...Master cylinder, 20...Pilot operation unit, 22...Solenoid switching valve, 23... Crane overload prevention detection device, 24... Memory device, 25... Hanging load detector, 30... Free fall limit load calculator, 31... Comparator, 32...
Solenoid switching valve.

Claims (1)

[Scope of Claims] 1. A winding drum clutch control circuit including a clutch engagement cylinder that is always energized to disengage, and a clutch control valve that selectively connects the clutch engagement cylinder to either a hydraulic power source or a tank. In a crane winding barrel device equipped with a manually operable winding barrel brake,
A detection device that issues a signal when the suspended load reaches the free-fall limit load is provided so that it can be activated during free-fall, and the signal generated by the detection device causes the clutch engagement cylinder at the clutch disengagement position to be connected only to the hydraulic source. A safety device for freely lowering a suspended load, characterized in that a connecting oil path switching device is provided in a hoisting drum clutch control circuit. 2. A pilot operating section is provided on the clutch control valve so that the oil passage switching device can switch the clutch control valve from the clutch disengaged position to the clutch engaging position, and the pilot operating section is normally communicated with the tank; 2. A safety device for freely lowering a suspended load according to claim 1, comprising a switching valve that switches and connects the pilot operating section to a hydraulic power source when receiving a signal issued by the detection device. 3 As an oil passage switching device, the clutch engagement cylinder is normally connected to the clutch control valve, but when a signal from the detection device is received, the switching valve that switches and connects the clutch engagement cylinder directly to the hydraulic power source is connected. A safety device for free lowering a suspended load as claimed in claim 1, which is inserted into a circuit between the clutch engaging cylinder and the clutch control valve.