JPS6131717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boom extension/retraction device suitable for the boom of a crane, etc., and particularly relates to a device configured to sequentially extend/retract the boom, and has a simple structure and high reliability. The aim is to provide equipment.

1 to 8 are explanatory views of one example of the present invention, and FIG. 1 shows the boom in its most retracted state. In Fig. 1, 1, 2, and 3 are respectively the proximal boom;
This is a boom device for cranes, etc., which has an intermediate boom and a tip boom that are slidably fitted in sequence. A is first
In the cylinder device, the end of the piston rod _a2 of this cylinder device A is pivotally connected to the base boom 1, and the piston rod side of cylinder _a1 is pivotally connected to the intermediate boom 2, thereby connecting the intermediate boom to the base boom. Expand and contract. B is a second cylinder device, and the end of cylinder b ₁ of this cylinder device B is pivotally connected to the intermediate boom, and the end of piston rod b ₂ is pivotally connected to the tip boom, thereby allowing the tip boom to extend and retract with respect to the intermediate boom. let 4 is an oil tank, 5 is a pump, 6 is a switching valve, and 7 and 8 are piping connected to this switching valve 6 and ports 9 and 10 provided at the end of the piston rod _A2 of the first cylinder device A, respectively. .

Now, the first cylinder device A is configured as follows. The piston rod _a2 is constructed as a double pipe, and an outer oil passage 11 communicating with the port 9 communicates with a contraction side oil chamber 12. Furthermore, inside the inner oil passage 13 communicating with the port 10, an intermediate pipe 16 that is connected to an oil passage 17 provided on the cylinder end 15 side penetrates through the piston 14 and projects therein. The pipe 16 is slid and moved tightly.

The oil passage 17 is connected to the oil chamber 24 within the cylinder end 15.
and is branched to port 19. Furthermore, an oil chamber 2 that communicates with the extension side oil chamber 22 is located at the cylinder end 15.
1 is provided, and this oil chamber 21 communicates with the oil chamber 24. A first pilot operated check valve 18 is provided in the oil chamber 21 to allow oil to flow from the oil chamber 24 to the oil chamber 21 but to prevent the reverse flow, and is biased in the closing direction by a spring 20. There is. Note that when pilot pressure is activated in one of the oil chambers 24a of the oil chamber 24,
A pilot piston 23 is provided for actuating the first operated check valve 18.

Next, in the second cylinder device B, 25 is a piston, 26 is an extension side oil chamber, and 27 is a contraction side oil chamber. Furthermore, the cylinder end portion 29 of this cylinder device B has an oil chamber 3 that communicates with the extension side oil chamber 26.
1. Further, an oil chamber 32 communicating with this oil chamber 31 is provided.
The second part allows oil to flow into the first part and prevents its reverse flow.
A pilot operating check valve 28 is provided, and this second pilot operating check valve 28 is biased in its closing direction by a spring 30. The oil chamber 32 is provided with a pilot piston 33 that operates the second pilot operated check valve 28 when pilot pressure acts on one oil chamber 32a of the oil chamber 32.

Next, reference numeral 34 denotes a first switching valve provided at a proper position at the base end of the intermediate boom 2, which is composed of a valve body 35 and a poppet 36 provided inside the valve body 35 with a piece 36a protruding outside the valve body. is spring 3
7, the oil chamber 38 and the oil chamber 39 are urged in the closing direction, but as the first cylinder device A extends, the intermediate boom 2 extends and the poppet 36
The oil chamber 38 and the oil chamber 39 are configured to open when the piece 36a comes into contact with the tip of the proximal boom. Reference numeral 63 designates a check valve provided within the poppet 36, which allows flow from the oil chamber 39 to the oil chamber 38 and prevents the reverse flow. In addition, 40 is a pipe connecting the port 41 provided in the oil chamber 38 and the port 19 provided in the cylinder end portion 15 of the first cylinder device A described above, and 42 is a pipe connecting the port 43 provided in the oil chamber 39 and the port 19 provided in the cylinder end portion 15 of the first cylinder device A described above. This is a pipe that connects a port 57 that communicates with the oil chamber 32 provided in the cylinder end portion 29 of the second cylinder device B.

Next, reference numeral 44 denotes a second switching valve installed at a suitable position at the base end of the intermediate boom 2, which is composed of a valve body 45 and a poppet 46 provided inside the valve body 45 with a piece 46a protruding outside the valve body. is spring 4
7, the oil chamber 48 and the oil chamber 49 are biased in the closing direction, but as the second cylinder device contracts, the tip boom 3 contracts, and the piece 46a of the poppet 46 is moved to the base of the tip boom. When it comes into contact with the end,
The oil chamber 48 and the oil chamber 49 are configured to open.

In addition, 50 is a pilot pipe connecting the port 51 provided in the oil chamber 48 and the port 55 provided in the oil chamber 32a described above, and 52 is a pilot pipe connecting the port 53 provided in the oil chamber 49 and the port 53 provided in the oil chamber 24a described above. port 56
This is the pilot piping that connects the

Next, 58 is a pipe connecting the port 59 provided in the reduction side chamber 12 of the first cylinder device A and the port 60 provided in the reduction side oil chamber 27 of the second cylinder device B, and 61 is a branch from the pipe 58. The oil chamber 3 mentioned above
This is pilot piping that connects to the port 62 provided at 2a.

Next, the effect will be explained.

Figure 1 shows the boom in its most retracted state. Now, when the switching valve 6 is switched to the position 6a (see Fig. 2), the pressure oil from the pump 5 reaches the pipe 8, the port 10, the oil line 13, the middle pipe 16, and the oil line 17, where it branches. One of the pressure oils that reached the oil chamber 24 pushes open the first pilot operated check valve 18 and flows into the extension side oil chamber 22, and then flows into the first cylinder device A.
is extended, and thereby the intermediate boom 2 is also extended.
On the other hand, the pressure oil that has reached the port 19 reaches the oil chamber 38 of the first switching valve 34 via the pipe 40, but is stopped there because the poppet 36 is in an inactive state. As the first cylinder device A expands, the oil in the contraction side oil chamber 12 flows through the oil passage 11, the port 9, and the piping 7.
The oil is drained into the tank via.

When this state continues and the first cylinder device A reaches its maximum extension, a piece 36a of the poppet 36 of the first switching valve 34 provided at a suitable position at the base of the intermediate boom 2 comes into contact with the tip of the base boom 1, causing the poppet to open. 36 is moved to communicate the oil chamber 38 and the oil chamber 39. Then, the pressure oil that had been stopped in the oil chamber 38 is transferred to the oil chamber 39, the piping 42, and the oil chamber 32 provided in the cylinder end portion 29 of the second cylinder device B, and this pressure oil is transferred to the second pilot operated check valve. 28 is pushed open to reach the extension side oil chamber 26, and the second cylinder device B becomes in an extendable state (FIG. 3).

When the second cylinder device B begins to extend, the tip boom 3 begins to extend further than the intermediate boom (FIG. 4).
Note that as the second cylinder device B expands, the oil in the contraction side oil chamber 27 flows through the port 60, the piping 58, and the port 5.
9. Oil is drained into the tank via the contraction side oil chamber 12 and oil passage 11 of the first cylinder device A.

Note that even when the second cylinder device B is extended, pressure oil is always acting on the extension side oil chamber 22 of the first cylinder device A, so that the first cylinder device A maintains the extended state. When the second cylinder device B is extended, for some reason the first cylinder device B
The cylinder device A does not shrink.

Next, the case of reduction will be explained (see FIG. 5).

With the boom fully extended, turn the switching valve 6 to 6.
When switched to position c, the oil from the pump 5 crosses the piping 7, port 9, and oil passage 11 and acts on the reduction side oil chamber 12 of the first cylinder device A, and also flows through the port 59 and piping 58. Second cylinder device B
It also acts on the contraction side oil chamber 27. Here, since the oil in the extension side oil chamber 22 of the first cylinder device A is stopped by the first pilot operated check valve 18, the first cylinder device A does not contract. The pressure oil acting on the contraction side oil chamber 27 of the second cylinder device B simultaneously acts on the oil chamber 32a via the pilot pipe 61 branched from the pipe 58, moves the pilot piston 33, and thereby the second pilot operator Activate the idle check valve 28. Therefore, the extension side oil chamber 2 of the second cylinder device B
The oil in No. 6 is supplied to the oil chamber 31, oil chamber 32, port 57, piping 42, oil chambers 39 and 38 of the switching valve 34, and piping 4.
0, port 19, oil line 13, port 10, piping 8
The oil is drained into the tank via the second cylinder device B.
decreases (Figure 5).

Due to the reduction of the second cylinder device B, the tip boom 3
However, when the second cylinder device B becomes the most contracted state, the base end of the tip boom 3 comes into contact with one piece 46a of the poppet 46 of the second switching valve 44 provided at the base of the intermediate boom 2, and the poppet 46 is moved and communicates with the oil chamber 48 and the oil chamber 49. Then, the pilot piping 61, oil chamber 32a, pilot piping 50
The pressure oil that was acting on the oil chamber 48 through the oil chamber 4
9. Acts on the oil chamber 24a via the pilot piping 52, thereby moving the pilot piston 23, operating the first pilot operated check valve 18, and bringing the first cylinder device A into a retractable state (the first Figure 6).

When the first cylinder device A starts to retract, the tip boom 3 starts to retract into the intermediate boom 2 (the seventh
figure). In addition, as the first cylinder device A is reduced, the oil in the extension side oil chamber 22 is transferred to the tank via the oil chamber 21, the oil chamber 24, the oil passage 17, the middle pipe 16, the oil passage 13, the port 10, and the piping 8. The oil is drained.

Note that when the first cylinder device A is in the reduced operating state, the pressure oil from the pump is transferred to the second cylinder device B.
Since the extension side oil chamber 26 always communicates with the tank side, the second cylinder device B always maintains the contracted state.

Note that FIG. 8 shows the poppet 3 of the first switching valve 34.
6 is an explanatory diagram of the check valve 63 provided in the middle boom 6. For example, when the tip boom 3 is retracted (therefore, the second cylinder device B is retracted), the intermediate boom 2
is reduced (therefore, the first cylinder device A is reduced), the drained oil in the extension side oil chamber 26 of the second cylinder device B is removed because the poppet 36 in the first switching valve 34 is in an inactive state. , is provided so as not to be stopped by the oil chamber 39 of the first switching valve 34.

As described above, the present invention includes a proximal boom, an intermediate boom, and a distal boom that are slidably fitted in order, a first cylinder device between the proximal boom and the intermediate boom, and a second cylinder device between the intermediate boom and the distal boom. In a three-stage boom extension and retraction device each equipped with a cylinder device, the flow of oil to the extension side oil chamber from the oil supply/discharge device to the extension side oil chamber of the first cylinder device is midway through the supply/discharge circuit. However, a first pilot operated check valve configured to allow this backflow is made possible by being operated by the pilot pressure during the contraction operation, is provided to supply the oil from the oil supply/drainage device to the extension side oil chamber of the second cylinder device. A first switching valve, a check valve connected in parallel with this, and a second pilot operated check valve are connected in the middle of the exhaust circuit from the upstream side, and the first switching valve is at the terminal position of the intermediate boom extension operation. configured to operate to open an oil passage to the second pilot operated check valve;
The check valve is configured to allow oil to flow from the extension side oil chamber side of the second cylinder device but prevent the reverse flow thereof, and the second pilot operated check valve is configured to allow oil to flow from the extension side oil chamber side of the second cylinder device. Although the flow of oil to the cylinder is allowed, the reverse flow is enabled by being actuated by the pilot pressure during the reduction operation, and the oil chambers on the reduction side of the first and second cylinder devices are communicated with each other. These oil chambers are connected to an oil supply/drainage device, and a pilot pressure circuit is provided so that the first and second pilot operated check valves are pilot operated by the pilot pressure from these reduction side oil chambers during a reduction operation. a second switching valve configured to operate at the terminal position of the retraction operation of the tip boom to open the pilot pressure circuit;
When the first and second cylinder devices are extended, the first pilot pellet check valve is opened by pressure oil, and pressure oil always enters the extension side oil chamber of the first cylinder device. When retracting, the second pilot operated check valve is operated by pilot pressure to always communicate the oil chamber on the extension side of the second cylinder device to the tank side, and the first and second switching valves are connected to the intermediate boom. (1) When extended, the cylinder device on the proximal end side can always be extended, and when retracted, the cylinder device is always able to extend. The cylinder device on the distal end side can always be retracted, so when the cylinder device is extended in any state, it always extends from the cylinder device on the proximal end side, and when it is retracted, the cylinder device on the distal end side is always retracted. Therefore, no malfunction occurs. Even if this happens, it will always expand and contract in the normal order.

(2) A switching valve that switches the oil path at the end of extension and retraction of the cylinder device is provided outside the cylinder device, and the switch is made at the end of extension and retraction of the boom device, so the cylinder device itself is not complicated and manufacturing is simple. Also, since the switching valve is located outside the cylinder device, installation and adjustment of the switching valve are easy, and maintenance is easy.

It has the following effects.

[Brief explanation of the drawing]

1 to 8 are explanatory diagrams of the present invention, and FIG. 9 is a hydraulic circuit diagram. A...First cylinder device, B...Second cylinder device, 18...First pilot operation check valve, 28...Second pilot operation check valve, 23, 33...Pilot piston, 34...No. 1 switching valve, 44...second switching valve.

Claims (1)

[Claims] 1 Base boom 1, intermediate boom 2, tip boom 3
and sequentially slidably fit the first cylinder device A between the base end boom 1 and the intermediate boom 2, and the first cylinder device A between the base end boom 1 and the intermediate boom 2.
In a three-stage boom extension and retraction device in which a second cylinder device B is provided between the tip boom 3 and the tip boom 3,
In the middle of the supply and discharge circuit from the oil supply and discharge device to the extension side oil chamber 22 of the first cylinder device A, this extension side oil chamber 22
A first pilot operation check valve 18 is provided, which allows oil to flow to the cylinder B, but allows reverse flow by being actuated by the pilot pressure during the reduction operation, and connects the oil supply and discharge device to the second cylinder device B. In the middle of the supply and discharge circuit to the extension side oil chamber 26,
A first switching valve 34, a check valve 63, and a second pilot operated check valve 28 are connected from the upstream side thereof, and the first switching valve 34 is activated at the end position of the extension operation of the intermediate boom 2. The check valve 63 is configured to open an oil passage to the second pilot operated check valve 28, and the check valve 63 is connected to the extension side oil chamber 26 of the second cylinder device B.
The second pilot operated check valve 28 is configured to allow the flow of oil from the side but prevent the reverse flow, and the second pilot operated check valve 28 allows the flow of oil to the extension side oil chamber 26 of the second cylinder device B, but prevents the flow of oil from the side. The configuration is such that the reverse flow is enabled by being actuated by the pilot pressure during the reduction operation, and the reduction side oil chambers 12 and 27 of the first and second cylinder devices A and B are communicated with each other so that these oil chambers are while connecting it to the oil supply/drainage device.
A pilot pressure circuit is connected so that the first and second pilot operated check valves 18 and 28 are pilot operated by the pilot pressure from these reduction side oil chambers during the reduction operation, and the first pilot operated check valve is operated by the pilot pressure from the reduction side oil chamber. The tip boom 3 is inserted into the pilot pressure circuit to pilot operate the valve 18.
A second switching valve 44 is provided which is configured to operate at the end position of the contraction operation to open this pilot pressure circuit, and when the first and second cylinder devices A and B are extended, the first pilot operated check valve 1
8 is opened by pressure oil, and pressure oil always enters the extension side oil chamber 22 of the first cylinder device A, and when the first and second cylinder devices A and B are contracted, the second pilot operated check valve 28 is opened. The oil chamber 26 on the extension side of the second cylinder device B is operated by pilot pressure to always communicate with the tank side, and the first and second switching valves 34 and 44 are connected to the intermediate boom 2.
A three-stage boom extension and retraction device, characterized in that it is configured to be operated by being provided at the base of the boom and colliding with the ends of the respective booms.