JPH0569072U - Hydraulic drive winch drop prevention device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] In a hydraulic drive winch configured to hold a suspended load for a long time by braking a winch drum with a negative brake, a supply / discharge oil passage on the load holding side. Eliminate the problem that the hydraulic pressure between the hydraulic motor and the counter-balance valve in (1) decreases due to oil leakage from the hydraulic motor, and the suspended load drops when the hydraulic drive winch is started. [Structure] The oil supply / discharge oil passage 6a on the load holding side of the hydraulic motor 2
6b and the hydraulic source are connected by a replenishment oil passage 13 having an opening / closing valve 14, and an opening / closing valve control means 15 for controlling opening / closing of the opening / closing valve is provided, and the opening / closing valve control means is the operation lever-3a.
A pulse electric signal for opening the opening / closing valve for a minute time is output to the opening / closing valve by a detection signal from an operation detecting means 16 for detecting the tilting operation of No. 3 in an invalid tilting range in which the hydraulic switching valve 4 is not switched yet.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drop prevention device for preventing a drop of a suspended load that occurs when a hydraulic drive winch is started.

[0002]

[Prior Art]

 As shown in FIG. 2, a hydraulic drive winch used in a mobile crane or the like has a hydraulic switching valve 4 that is operated to switch a hydraulic motor 2 for driving a winch drum 1 by an operating device 3 having an operating lever 3a. In addition to the drive control, the winch drum 1 is provided with a brake releasing cylinder 5a and a negative brake 5 which is released when pressure oil is supplied to the brake releasing cylinder 5a. Pressure oil is supplied to the brake release cylinder 5a in conjunction with the switching of the above. A counterbalance valve 8 is provided in the oil supply / exhaust oil passage 6a of the pair of oil supply / exhaust oil passages 6a, 6b connecting the hydraulic motor 2 and the hydraulic pressure switching valve 4 on the side that holds the load, and a winch drum is installed. The hydraulic motor 2 is prevented from running away during the unwinding drive.

In the example of FIG. 2, the brake releasing cylinder 5a of the negative brake 5 is connected via a shuttle valve 7 to supply / discharge oil passages 6a and 6b connecting between the hydraulic motor 2 and the hydraulic switching valve 4. When the hydraulic pressure switching valve 4 is switched, a part of the pressure oil supplied to the hydraulic motor 2 through the hydraulic pressure switching valve 4 is supplied to the brake releasing cylinder 5a. Further, in this example, the operation device 3 outputs an electric signal corresponding to tilting operation in the forward and reverse directions from the neutral position of the operation lever 3a to the electric signal transmission paths 3c and 3d. Pilot pressure generating section for receiving the signal output section 3b and the operation electric signals from the operation electric signal output section 3b and generating hydraulic pressures corresponding to these electric signals in the pilot pressure lines 3e and 3f of the hydraulic pressure switching valve 4. It is composed of 3g.

In the figure, 9 is a relief valve interposed between a pump oil passage 10 for supplying high-pressure oil to the hydraulic pressure switching valve 4 and a tank 11.

In the hydraulic drive winch configured as described above, the operating lever 3a of the operating device 3 is operated to switch the hydraulic switching valve 4 to control the winch drum 1 to wind up, wind down, and stop. It is a thing. In this type of hydraulic drive winch, since the winch drum 1 is braked by the negative brake 5 in the stopped state, even if the suspended load W is held in the suspended state for a long time, the hydraulic motor 1 and the counter balance are counterbalanced. This has an advantage that the suspended load W does not drop due to oil leakage of the valve 8 and the hydraulic pressure switching valve 4.

However, in this type of hydraulically driven winch, in the stopped state, the hydraulic pressure between the hydraulic motor 2 and the counter balance valve 8 in the oil supply / exhaust passage 6a on the side that holds the load is the hydraulic motor 2 or the counter. There is a problem that the suspended load W drops when the hydraulic drive winch is started, because the balance valve 8 is reduced by oil leakage. The reason is that if the hydraulic switching valve 4 is switched when the hydraulic drive winch is started (raised or lowered), the negative brake 5 is released in conjunction with this switching. This is because the oil is supplied from the counterbalance valve 8 and the hydraulic motor 2 on the load holding / supplying / discharging path 6a on the load holding side without sufficient pressure oil to hold the suspended load W.

[0007]

[Problems to be solved by the device]

 SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems of the prior art and to provide a drop prevention device for preventing the hanging load W from dropping at the time of starting.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the device for preventing the drop of a hydraulically driven winch of the present invention is constructed as follows. That is, the hydraulic motor 2 for driving the winch drum 1 is configured to be driven and controlled by a hydraulic pressure switching valve 4 which is switched by an operating device 3 having an operating lever 3a, and the winch drum 1 is provided with a brake releasing cylinder. 5a is attached to the brake release cylinder 5a, and a negative brake 5 for releasing the brake when the pressure oil is supplied to the brake release cylinder 5a is attached to the brake release cylinder 5a. A hydraulic drive winch configured to supply, in particular, a counter in the supply / drain passage 6a of the pair of supply / drain passages 6a, 6b connecting the hydraulic motor 2 and the hydraulic switching valve 4 on the side holding the load. A device for preventing drop of a hydraulic drive winch, which is provided with a balance valve (8), which comprises a pair of connecting the hydraulic motor (2) and the hydraulic switching valve (4). A supply oil passage between the supply / discharge circuit 6a on the load holding side of the supply / discharge oil passages 6a and 6b and the hydraulic pressure source is provided with a normally-closed on-off valve controlled to open / close by an electric signal. An opening / closing valve control means for controlling the opening / closing of the opening / closing valve is attached, and the opening / closing valve control means detects the tilting operation of the operating lever 3a in an invalid tilting range in which the hydraulic pressure switching valve 4 is not switched yet. It is provided with a detecting means, and when the operation detecting means detects a tilting operation of the operation lever 3a, it is configured to output a pulse electric signal for releasing the opening / closing valve for a minute time to the opening / closing valve. Preventing drop of hydraulically driven winches.

[0009]

[Action]

 According to the drop prevention device for the hydraulic drive winch of the present invention thus constructed, when the operation lever 3a is tilted from the neutral position, the operation detecting means does not switch the tilting operation yet. A pulse electric signal is output from the on-off valve control means for detecting the temperature in the region and opening the on-off valve for a minute time. As a result, the on-off valve is opened for a minute time before the hydraulic pressure switching valve 4 is opened, and the pressure oil is supplied from the hydraulic power source to the load holding / supplying oil passage 6a via the on-off valve. Therefore, the oil pressure in the oil supply / exhaust passage 6a on the load holding side between the counter balance valve 8 and the hydraulic motor 2 rises before the opening of the oil pressure switching valve 4 and the release of the negative brake 5, and the negative brake 5 Therefore, the suspended load W does not drop when releasing the.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic drive winch drop prevention device of the present invention will be described below with reference to FIG. Since the hydraulic drive winch drop prevention device of the present invention is used in the conventional hydraulic drive winch shown in FIG. 2 and described above, the above-mentioned reference numerals are used as synonyms in the following description. ..

In FIG. 1, reference numeral 12 denotes a hydraulic pressure source, which is constituted by a pressure accumulator in which high pressure oil is constantly accumulated in this example. Reference numeral 13 denotes a replenishment oil passage connecting the oil supply source / discharge circuit 6a on the side holding a load to the hydraulic power source 12 among the pair of oil supply / discharge passages 6a, 6b connecting the hydraulic motor 2 and the hydraulic pressure switching valve 4. A normally-closed on-off valve 14 whose opening and closing is controlled by an electric signal is interposed in the supply oil passage 13.

Reference numeral 15 is an opening / closing valve control means for outputting an electric signal for controlling opening / closing of the opening / closing valve 14. The on-off valve control means 15 includes operation detection means 16 for detecting a tilting operation of the operation device 3. The operation detecting means 16 detects the tilting operation of the operating lever 3a in the tilting range of the operating lever 3a in which the hydraulic pressure switching valve 4 is not yet switched, that is, the invalid tilting range of the operating lever 3a. Specifically, the operation detecting means 16 is such that the hydraulic pressure switching valve 4 does not switch the change in the potential generated in the electric signal transmission paths 3c and 3d of the operating device 3 when the operation lever 3a is tilted (the pump oil path). 10 and the oil supply / drain passage 6a or 6b are not yet connected), and is composed of a pair of comparators 16a and 16b which output an electric signal upon detection. In FIG. 1, reference numeral 16c is a reference voltage generator for applying a reference electric signal to the comparators 16a and 16b. Reference numeral 17 denotes a pulse electric signal generator for outputting a pulse electric signal for releasing the opening / closing valve 14 for a minute time when a detection signal of the operation detecting means 16, that is, an electric signal output by the comparators 16a and 16b is input. is there.

Next, the operation will be described. When the operation lever 3a of the operation device 3 is tilted (tilted from the neutral position) in an attempt to wind up or wind down the hydraulic drive winch, the operation detection means 16 in the opening / closing valve control means 15 causes the operation lever 3a to tilt. The detection is performed in the ineffective tilting range where the hydraulic pressure switching valve 4 is not yet switched. At the time of this detection, a pulse electric signal is generated from the pulse electric signal generator 17 of the opening / closing valve control means 15, and the opening / closing valve 14 is released for a minute time by this signal. As a result, high-pressure oil is instantaneously supplied from the hydraulic pressure source 12 to the load holding / supplying / discharging passage 6a, and the hydraulic pressure between the counter balance valve 8 and the hydraulic motor 2 in the supplying / discharging passage 6a rises. With the tilting operation of the operation lever 3a thereafter, the hydraulic pressure switching valve 4 is switched and the negative brake 5 is released, so that the suspended load W of the hydraulic drive winch is moved to the counter balance valve 8 and the hydraulic motor in the oil supply / exhaust passage 6a. It is held by the hydraulic pressure between the two, but at that time, since the hydraulic pressure in the oil supply / discharge passage 6a on the load holding side between the counterbalance valve 8 and the hydraulic motor 2 has already risen, the suspended load W Can be prevented as much as possible.

In the above embodiment, the width of the pulse electric signal generated from the pulse electric signal generator 17 of the opening / closing valve control means 15 is set to a fixed minute time. , The width is increased as the weight of the suspended load W is increased, and the opening time of the on-off valve is increased as the weight of the suspended load W is increased so that the open / close valve is connected between the counter balance valve 8 and the hydraulic motor 2. By ensuring the hydraulic pressure corresponding to the suspended load W 1 in the oil supply / discharge passage 6a on the load holding side, it is possible to completely eliminate the drop in the hydraulic drive winch when it is started. In this case, an appropriate load detecting means for detecting the weight of the suspended load W is provided, and the detection signal of this load detecting means is input to the pulse electric signal generator 17 of the on-off valve control means 15 to generate the pulse electric signal generator. It is sufficient to generate a pulse electric signal having a pulse width corresponding to the suspended load W at 17. The load detecting means may be a three-point sheave type load detecting means interposed on a wire rope for suspending the suspended load W, or the hydraulic drive winch of the present invention may be used as a winch of a mobile crane. When used, the suspended load W is calculated from the load (moment around the undulating fulcrum) acting on the boom of the mobile crane and the operating posture of the boom (boom length and boom undulating angle). You can use what you do.

[0015]

[Effect of the device]

 The drop-prevention device for hydraulically driven winches of the present invention configured and operated as described above has the problem of the conventional hydraulically-operated winches, that is, the suspended load W drops (a small amount drops) at the time of starting. Therefore, it is possible to achieve the effect that the hydraulic drive winch can be started smoothly.

[Brief description of drawings]

FIG. 1 is an explanatory view of a drop prevention device for a hydraulic drive winch according to the present invention.

FIG. 2 is an explanatory view of a conventional hydraulic drive winch.

[Explanation of symbols]

 1 Winch Drum 2 Hydraulic Motor 3 Operating Device 3a Operating Lever 4 Hydraulic Switching Valve 5 Negative Brake 5a Brake Release Re-Cinder 6a, 6b Supply / Discharge Oil Path 8 Counterbalance Valve 12 Hydraulic Source 13 Supply Oil Path 14 Open / Close Valve 15 Open / Close Valve Control Means 16 Operation Detection Means 17 Pulsed Electric Signal Generator

Claims (1)

[Scope of utility model registration request] 1. A hydraulic motor 2 for driving a winch drum 1.
Is driven and controlled by a hydraulic pressure switching valve 4 which is switched by an operating device 3 having an operating lever 3a, and the winch drum 1 is provided with a brake releasing cylinder 5a.
A hydraulic drive winch which is equipped with a negative brake 5 for releasing the brake when the pressure oil is supplied to a, and is configured to supply the pressure oil to the brake releasing cylinder 5a in conjunction with the switching of the hydraulic pressure switching valve 4. In particular, a pair of oil supply / drain passages 6 connecting the hydraulic motor 2 and the hydraulic switching valve 4
A hydraulic drive winch size drop prevention device in which a counterbalance valve 8 is provided in the oil supply / discharge oil passage 6a on the load holding side of a and 6b, which connects the hydraulic motor 2 and the hydraulic switching valve 4. Of the pair of oil supply / discharge passages 6a, 6b for holding the load, the supply / discharge circuit 6a
The hydraulic pressure source 12 and the hydraulic power source 12 are connected by a replenishment oil passage 13 having a normally-closed on-off valve 14 controlled to open and close by an electric signal, and an on-off valve control means for controlling the on-off of the on-off valve 14. The on-off valve control means 15 is equipped with an operation detecting means 16 for detecting the tilting operation of the operating lever 3a in an invalid tilting range in which the hydraulic pressure switching valve 4 is not yet switched, and the operation detecting means 16 operates. A drop prevention device for a hydraulically driven winch, characterized in that a pulse electric signal for releasing the opening / closing valve 14 for a very short time is output to the opening / closing valve 14 when a tilting operation of the lever 3a is detected.