JPS6143835Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a three-stage cylinder device suitable for a boom of a crane or the like.

The applicant has previously published Japanese Patent Application No. 51-137208 (Japanese Unexamined Patent Publication No. 53-62077) regarding this type of three-stage cylinder device.
(No.), Patent Application No. 150067 (1982) (Japanese Patent Application No. 78809 (1982))
However, while the earlier application used a pilot operating system in terms of functions, the present application simplifies the device by using a direct operating system for these functions.

Embodiments of the present invention will be described below with reference to the drawings.

In the drawing, the first and second cylinders of the three-stage cylinder device are indicated by A and B, respectively, 1 is an oil tank, 2 is an oil pump, 3 is a control valve,
These constitute an oil supply and discharge device. 4 is a pipe connected from the control valve to the extension side oil chamber of the three-stage cylinder device, 5 is a pipe connected to the contraction side oil chamber, and 6 is installed at the end of the piston rod C leading to the contraction side oil chamber of the three-stage cylinder device. 8 is a port that also communicates with the extension side oil chamber, 9 is a passage in the piston rod C that communicates with the contraction side oil chamber, and 10 is the first port.
This is a reduction side oil chamber of the cylinder A, and communicates with the passage 9 through a passage 56. Reference numeral 12 denotes a medium pipe configured as a double pipe, which is provided in the piston rod C of the first cylinder A, passes through the piston 15 of the first cylinder A, and extends to the piston 18 of the second cylinder B.
A first valve 24 is provided on the piston 18 side. Further, the middle pipe 12 is normally pushed to the left by the spring 21, and the first valve 24 blocks off the oil chamber 22 and the oil chamber 34, but at the end of the extension of the first cylinder A, the end 54 of the middle pipe 12 is the piston 15 of the first cylinder A
, the first valve 24 is activated, and the first valve 24 is activated.
The oil chamber 22 and the oil chamber 34 are configured to communicate with each other.
7 and 13 are passages passing through the middle pipe 12, and the passage 7 communicates with the passage 9 in the rod C mentioned above, and also includes a hole 52, an oil chamber 53 provided on the piston 18 side,
Reduction side oil chamber 1 of second cylinder B via passage 11
4, it becomes an oil drainage passage when the extension is activated, and becomes an oil supply passage when the contraction is activated. Also aisle 1
One side of the piston rod C is configured to communicate with the aforementioned port 8 via a pipe 55 provided on the end side of the piston rod C, and the other side communicates with an oil chamber 57 within the first valve 24. 23 is this oil chamber 57 and the oil chamber 2 mentioned above.
A passage 33 connecting 2 is a check valve provided in an oil chamber 57 and is constantly biased by a spring 48.
The flow from the oil chamber 34 to the oil chamber 57 side is allowed, and the reverse flow is blocked. 58 is a passage connecting the extension side oil chamber 20 and the oil chamber 34 of the second cylinder B. Reference numeral 38 denotes a second valve provided on the piston 18 of the second cylinder B, which is constantly biased by a spring 35 to open an oil chamber 59 and an oil chamber 6.
0 is closed, but when pressure oil acts on the oil chamber 59, it has a check function that allows oil to flow from the oil chamber 59 to the oil chamber 60, but prevents its reverse flow. Note that the second valve 38 is in an unrestricted state and its one end 38 is closed.
a protrudes into the extension side oil chamber 20 of the second cylinder B, and at the end of the contraction of the second cylinder B, this one end 38a comes into contact with the cylinder end 19 of the second cylinder B, and the second valve 38 is activated by the spring. 35 so that the oil chamber 59 and the oil chamber 60 communicate with each other. 61 is a passage connecting the oil chamber 59 and the aforementioned oil chamber 22, and 62 is a passage connecting the oil chamber 60 and the extension side oil chamber 16 of the first cylinder A. Further, the second valve 38 is provided with a hole 39, and the second valve 38 communicates with the oil chamber 49 so that the pressure is balanced so that the second valve 38 is not affected by the pressure oil in the extension side oil chamber 20 of the second cylinder B. Note 5
1 is the ground part of the first cylinder A, and 63 is a counterbalance valve installed near the inlets of ports 6 and 8 at the end of the piston rod C, which controls the flow of pressure oil from the piping 4 side to the port 8 side when it is extended. Although the flow in the opposite direction is blocked, it is operated by the pilot pressure from the oil supply side piping 5 side at the time of contraction to allow the flow in the opposite direction.

Next, the operation of the three-stage cylinder device configured as described above will be explained.

FIG. 1 shows the shortest time in the stored state. In this state, when the control valve 3 is pushed to the left and switched to the position shown in FIG. and enter the oil chamber 22. Since the first valve 24 is pushed to the left by the spring 21, the oil chamber 22 and the oil chamber 34 are not in communication with each other, and therefore the pressure oil does not flow toward the extension side oil chamber 20 of the second cylinder B. Therefore, the second cylinder B does not extend. Oil chamber 2
The second pressure oil reaches the oil chamber 59 via the passage 61, crosses the oil chamber 60 and the passage 62, and flows into the extension side oil chamber 16 of the first cylinder A, so that the first cylinder A is extended.
In this case, if the second cylinder B is slightly extended and the end 38a of the second valve 38 is not pressed by the cylinder end 19 of the second cylinder B, the spring 35 causes the second valve 38 to close. Even when the oil chamber 59 and the oil chamber 60 are closed due to pressure, the second valve 38 is opened by the pressure oil acting on the oil chamber 59, and no pressure oil is supplied to the extension side oil chamber 16 of the first cylinder A. Flowing in, the first cylinder A expands. When the first cylinder A expands in this manner, the pressure oil in the contraction side oil chamber 10 of the first cylinder A returns to the tank 1 via the passage 56, passage 9, port 6, and piping 5.

As the state shown in FIG. 2 progresses and the first cylinder reaches its maximum extension, the end 54 of the middle pipe 12 and the piston 15 of the first cylinder A come into contact. At this point, the first valve 24 is still pushed to the left by the spring 21, so the circuit is the same as that shown in FIG.
When pressure oil enters 6, the force of spring 21 is applied to oil chamber 16.
It loses the thrust generated in the piston 15 by the pressure oil of
The first valve 24 is moved to the right, and the oil chamber 22 and the oil chamber 34 are
As a result, the state shown in FIG. 3 is reached.

As shown in FIG. 3, the oil chamber 22 and the oil chamber 34 communicate with each other, so that the pressure oil in the oil chamber 34 enters the extension side oil chamber 20 of the second cylinder B through the passage 58. This causes the second cylinder B to begin to expand. On the other hand, from the oil chamber 22, the passage 61 passes through the oil chamber 59, the oil chamber 60,
The pressure oil that communicated with the passage 62 and the extension side oil chamber 16 of the first cylinder A is
When the first cylinder comes into contact with the ground 51, the expansion of the first cylinder stops, and no further flow occurs.

FIG. 4 shows a state in which the first cylinder A stops extending and the second cylinder B continues to extend. When the second cylinder B extends, the end 38a of the second valve 38 comes into a non-contact state with the cylinder end 19 of the second cylinder B, and the second valve 38 is pushed to the left by the force of the spring 35, and the oil chamber 59 and the oil chamber 60.

Note that even if the oil chamber 59 and the oil chamber 60 are in a cutoff state, if the first cylinder A is in an expandable state (assuming that the first cylinder A is contracted for some reason), the pressure oil will flow to the second valve. 38 is pushed open and flows into the extension side oil chamber 16, and the first cylinder A is extended. This means that the first cylinder is always held in the most extended state during extension. As the second cylinder B expands, the oil in the contraction side oil chamber 14 returns to the tank through the passage 11, the oil chamber 53, the passage 7, the passage 9, and the port 6.

Next, for the contraction of the second cylinder B, pressure oil is sent to the contraction side oil chamber 14 of the second cylinder B and the contraction side oil chamber 10 of the first cylinder A, as shown in FIG.
The oil in the extension side oil chamber 16 of the first cylinder A cannot escape because the oil chamber 59 and the oil chamber 60 are shut off by the second valve 38, and therefore the first cylinder A does not contract. The oil in the extension side oil chamber 20 of the second cylinder B is
Passing through the passage 58, the oil chamber 34, the oil chamber 22, and the first valve 2
4, or directly via the check valve 33 to the oil chamber 57 in the first valve 24, and further into the tank via the passage 13 and port 8, so that the second cylinder B is contracted.

If the first cylinder A does not contract and only the second cylinder B contracts, the cylinder end 1 of the second cylinder
9 contacts the end 38a of the second valve 38 and overcomes the force of the spring 35 pushing the valve 38 to the left;
The oil chamber 59 and the oil chamber 60 communicate with each other, resulting in the state shown in FIG. 6.

As shown in FIG. 6, when the oil chamber 59 and the oil chamber 60 communicate with each other, the pressure oil in the extension side oil chamber 16 of the first cylinder A flows through the passage 62, the oil chamber 60, the oil chamber 59, the passage 61,
oil chamber 22, oil chamber 57 in first valve 24, passage 13,
Return to tank 1 via port 8. When the first cylinder A starts to contract, the piston 15 moves to the left, and the piston 15 and the end 54 of the middle pipe 12 come into a non-contact state, so the first valve 24 is returned to the left by the spring 21. The oil chamber 34 and the oil chamber 22 are shut off. At this time, if pressure oil accumulates in the oil chamber 34 etc., or even if the second cylinder B is not completely retracted, the expansion side oil chamber 20 of the second cylinder B The oil pushes open the check valve 33 and flows out to the tank side. This means that during contraction, the second cylinder B is always held in the minimum contraction state.

In this way, the extension side oil chamber 16 of the first cylinder A
As the oil returns to the tank 1, the first cylinder A becomes the most contracted state shown in FIG.

In addition, what is shown in FIG. 7 includes the first valve 24 and the second valve.
This shows another embodiment of the valve 38. In particular, the second valve 38 is provided with a check valve 64 inside, so that when the conventional oil chamber 59 and the oil chamber 60 are closed, the pressure in the oil chamber 59 is reduced. Oil used to flow into the oil chamber 60 by overpowering the spring 35, but now it flows through the check valve 64 in order to reduce pressure loss.

[Brief explanation of drawings]

Figure 1 is a sectional view of the three-stage cylinder device of the present invention.
2 to 6 are operation explanatory diagrams, and FIG. 7 is a diagram showing another embodiment. A...First cylinder, B...Second cylinder, C
... Piston rod, 10, 14 ... Reduction side oil chamber, 12 ... Middle pipe, 16, 20 ... Extension side oil chamber, 24 ... First valve, 38 ... Second valve, 33 ...
Check valve.

Claims (1)

[Scope of utility model registration request] In a three-stage cylinder device in which a first cylinder A having a piston 15 and a piston rod C is slidably fitted into a second cylinder B, the contraction side oil chambers 10 and 14 are communicated with each other to supply and drain oil. It is connected to the oil supply and discharge device, and is operated at the end of the extension of the first cylinder A during the extension, in the middle of the supply and discharge circuit from the oil supply and discharge device to the extension side oil chambers 16 and 20, and to the piston portion 18 of the second cylinder B. The first valve 24 communicates the oil supply side with the extension side oil chamber 20 of the second cylinder B, and the first valve 24 opens the extension side oil chamber 16 of the first cylinder A with the oil drain side by operating at the end of contraction of the second cylinder B during contraction. A second valve 38 is provided which communicates with the second cylinder B when the first valve 24 is retracted.
The extension side oil chamber 20 is always communicated to the oil drain side, and the second
When the valve 38 is extended, the oil supply side is always connected to the first cylinder A.
Further, the flow of oil to the extension side oil chamber is not allowed in the middle of piping from the oil supply/discharge device to the supply/discharge ports 6, 8 of this three-stage cylinder device. A three-stage cylinder, characterized in that it is provided with a counterbalance valve 63 that blocks the flow in the opposite direction but is operated by pilot pressure from the oil supply side at the time of reduction and allows the flow in the opposite direction. Device.