JPS6239024Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a simultaneous extension/retraction device for three or more stages of telescoping booms used in working machines such as cranes.

(Prior Art) As shown in Fig. 1, a telescopic boom of three or more stages used in a working machine such as a crane has a first boom tube 1 on the base end, and second and third boom tubes 2 on the distal side in order. ，
3 are telescopically inserted into each other, and the simultaneous telescoping device used therein includes double-acting hydraulic cylinders 4 and 5 disposed between each adjacent boom cylinder, and the double-acting hydraulic cylinders 4 .
5 are connected to the respective diversion ports 13' and 16' in the pump motor type flow dividing flow concentrating device 14 through independent oil supply and drainage passages 13 and 16, respectively, and the flow collecting side of the pump motor type flow dividing flow concentrating device 14 is connected to is connected to the other port of the directional control valve 9 via a second common oil supply/drainage path 17. In FIG. 1, 10 is a pump that supplies pressure oil to the directional control valve 9;
11 is a tank. Reference numerals 18 and 19 indicate negative pressure prevention valves provided in the branch passages 20 and 21 connected to the oil supply and discharge passages 13 and 16, respectively (when one of the cylinders is first contracted to the maximum during contraction, the valves on the most contracted side This valve is necessary because if there is no oil replenishment, negative pressure will occur and cause problems such as seizure.)
This allows oil to flow from the tank 11 to the oil supply and drainage passages 13 and 16.

In the simultaneous telescopic device configured as described above, by operating the directional switching valve 9, each of the double-acting hydraulic cylinders 6 and 7 is simultaneously driven to extend and contract by the same amount, and as a result, each boom of the multi-stage telescopic boom This allows the cylinder to expand and contract at the same time.

(Problems with the Prior Art) When retracting the telescopic boom using the simultaneous telescopic device as described above, the directional control valve 9 is operated to direct the oil discharged from the pump 10 through the first common oil supply and drainage path 8. , oil is supplied to the piston rod side oil chambers 6, 7 of the first and second cylinders 4, 5, and oil in the non-piston rod side oil chambers 12, 15 of the first and second cylinders 4, 5 is supplied to the oil supply/drainage passages 13, 16. The oil is returned to the tank 11 via the pump/motor type flow concentrator 14, the second common oil supply/drainage path 17, and the directional control valve 9, but the lengths of the oil supply/drainage path 13 and the oil supply/drainage circuit 6 are When comparing the oil supply and discharge passages 16 to the second cylinder 5 on the upper stage side, the total length is much longer than that of the oil supply and discharge passages 13, so the line resistance is different, and the pump
Diversion side port 1 of motor type diverter flow concentrator 14
The pressure at ports 3' and 16' is considerably higher on the port 13 side. When such a pressure difference is created, the pump/motor type flow dividing/collecting device 14 is driven by the oil pressure on the oil supply/discharge path 13 side, and as a result, the oil pressure on the oil supply/discharge path 16 side becomes negative pressure. Therefore, a portion of the oil in the tank 11 is sucked into the oil supply/drainage path 16 via the negative pressure prevention valve 19, and the contraction speed of the second cylinder 5 is delayed compared to the first cylinder 4. In addition, in the pump/motor type flow diverter flow collecting device 14, since the oil supply and drainage passage 13 side is under high pressure, oil leaks from the same oil passage 13 to the second common oil supply and drainage passage 17 side. This is a factor in the reduction speed being delayed compared to the first cylinder 4.

If the tip end cylinder contracts later than the proximal cylinder, when performing crane work by reducing the boom by an appropriate amount from the boom's maximum extension state, the tip end cylinder, which has a smaller moment of inertia, should be used. Since the tube is elongated more than the boom tube on the base end side, which has a larger moment of inertia, the allowable lifting load at that time is the allowable lifting load determined on the assumption that each boom tube is elongated by the same amount. There have been cases where the upper load has been exceeded to a large extent, resulting in accidents such as boom breakage.

The present invention provides a novel simultaneous telescopic boom telescoping device that solves the above problems with a simple structure.

(Means for Solving the Problems) The simultaneous extension and retraction device for a telescopic boom of three or more stages of the present invention is different from the conventional simultaneous extension and retraction device as described above.
The non-piston rod side oil chamber of the double-acting hydraulic cylinder 4 located at the base end of the oil supply/discharge passages 13 and 16 that connect the non-piston rod side oil chamber of each double-acting hydraulic cylinder and the pump/motor type flow dividing/collecting device. A valve device that resists the flow of oil flowing in the direction of the pump/motor type flow concentrator 14 in the oil supply and discharge passage 13 is installed in the oil supply and discharge passage 13 connected to the oil supply and discharge passage 13. When the boom is retracted, the difference in pipe resistance due to the difference in the length of the oil supply/discharge passage connecting the non-piston rod side oil chamber of each hydraulic cylinder and each branch port of the branch/concentrator is reduced, and the branch/distributor is The present invention is characterized in that it is configured to reduce the difference in pressure acting on each branch port in the flow device.

(Function) The simultaneous telescoping device for a three or more stage telescoping boom of the present invention configured as described above is connected to the oil supply/drainage path 13 connected to the non-piston rod side oil chamber of the double-acting hydraulic cylinder 4 located on the base end side. With the above-mentioned interposed valve device,
When the telescopic boom is retracted, the hydraulic pressure on each diversion port side of the pump-motor type flow concentrator 14 can be made almost the same, so that the retraction movement of the double-acting hydraulic cylinder on the tip side is smaller than that on the proximal side. This solves the problem of long delays.

(Example) An example of the present invention will be described based on FIG. 2 and subsequent figures. Reference numeral 1 shown in FIG. 1 and explained as the prior art
21 have the same meaning in the above description, so they are used here. Next, the configuration of the present invention will be explained in detail based on one specific embodiment.

A is a valve device installed in the oil supply and discharge passage 13, and has resistance to the flow of discharged oil from the non-piston rod side oil chamber 12 of the double-acting hydraulic cylinder 4 on the base end side. , the reverse flow, that is, the oil supplied to the non-piston rod side oil chamber 12 is allowed to flow freely. In this case, the pipe resistance of the oil supply and drainage line 13 when the telescopic boom is retracted is increased, and the outlet side port 13' of the pump/motor type diverter valve 14,
As a result of being able to reduce the pressure difference between the cylinders 16' as much as possible, the difference in the retraction speed of the boom barrel can be eliminated or reduced as much as possible. In the above embodiment, the valve device was composed of a check valve and a throttle valve, but the point is that any valve that provides resistance to the discharged oil may be used, and it can be switched as shown in Fig. 3. It goes without saying that it may be constructed of a valve, or that a check valve may be further provided as shown in FIG. 4 to provide resistance to the valve.

(Effects) The simultaneous extension and retraction device for three or more stages of telescopic booms of the present invention, which is constructed and operates as described above, can minimize the difference in the contraction speed of the boom cylinders on the proximal end and distal end sides, even with an extremely simple construction. Therefore, it is possible to prevent accidents such as breakage of the boom due to a contraction error of the simultaneous telescopic boom.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of a conventional simultaneous telescoping boom, Fig. 2 is a hydraulic circuit diagram of a simultaneous telescoping boom showing an embodiment of the present invention, and Figs. An example is shown. 4: Double-acting hydraulic cylinder, 5: Double-acting hydraulic cylinder, 6, 7: Piston rod side oil chamber, 8: First common oil supply/drainage path, 9: Directional switching valve, 12, 15: Non-piston rod side oil chamber, 11 :tank, 18,1
9: Negative pressure prevention valve, 20, 21: Branch path, 13,
16: Oil supply and drainage path, 14: Pump/motor type flow dividing and collecting device, 17: Second common oil supply and drainage path, A: Valve device.

Claims (1)

[Scope of utility model registration request] In particular, a simultaneous telescoping device used in a telescopic boom of three or more stages, in which a boom cylinder on the distal end side is telescopically inserted into a boom cylinder on the proximal end side in sequence, a double-acting hydraulic cylinder is arranged between each adjacent boom cylinder. At the same time, the piston rod side oil chambers of these double acting hydraulic cylinders are connected to one port of the directional control valve via the first common oil supply/drainage path, and the non-piston rod side oil chambers of each double acting hydraulic cylinder are connected to each other. It is connected to each branch port in the pump motor type flow dividing flow concentrating device through an independent oil supply and drainage path, and the flow collecting side of the pump motor type flow dividing flow concentrating device is connected in the above direction via a second common oil supply and drain path. A branch path connected to the other port of the switching valve and interposed with a negative pressure prevention valve that allows oil to flow from the tank to each oil supply/drainage path between the oil supply/drainage path and the tank. In a simultaneous telescopic device for three or more stages of connected telescopic booms, the oil supply/drainage path connecting the non-piston rod side oil chamber of the double-acting hydraulic cylinder and the pump motor type flow convergence device is located on the proximal end side. A valve device is installed in the oil supply/drainage path connected to the non-piston rod side oil chamber of the double-acting hydraulic cylinder to provide resistance to the flow of oil flowing in the oil supply/drainage path toward the pump motor flow concentrator. Therefore, when the telescopic boom is retracted, the difference in pipe line resistance due to the difference in the length of the oil supply and discharge passages connecting the non-piston rod side oil chamber of each hydraulic cylinder and each branch port of the flow dividing/concentrating device is reduced. 1. A simultaneous extension and retraction device for a telescopic boom of three or more stages, characterized in that the device is configured to equalize and reduce the difference in pressure acting on each branching port in the flow dividing and concentrating device.