JPH08184302A - Air bleeding structure for multistage hydraulic cylinder device - Google Patents

Abstract

PURPOSE: To easily bleed air mixed into a pressure oil (working oil) in a multistage hydraulic cylinder device. CONSTITUTION: A multistage hydraulic cylinder device has such an air bleeding structure as a pressure oil leading-in circuit 78 for leading-in a pressure oil is formed in the block 24 on a head side of a basic cylinder for composing a multistage hydraulic cylinder device, and a pressure oil supply circuit 80 to supply the pressure oil to the multistage hydraulic cylinder device and an air bleeding circuit 82 communicating with the outside are branched from the pressure oil leading-in circuit 78, and a change-over valve 84 to make the pressure oil leading-in circuit 78 alternatively communicate with the pressure oil supply circuit 80 or the air bleeding circuit 82 is provided at the above branched spot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air vent structure incorporated in a multistage hydraulic cylinder device.

[0002]

2. Description of the Related Art A multi-stage hydraulic cylinder device is stored (shortened).
It is widely used in various fields because it can take a large extension stroke with respect to this length. In particular, since it is most suitable for lifting a relatively light weight antenna, a camera, a workbench, etc., it is often used as a lift for these. By the way, since air enters the hydraulic cylinder during piping work, it is necessary to remove it. As this air bleeding structure, it is often adopted that an air bleeding hole is provided at the end of the cylinder, etc. ing.

[0003]

However, this is sufficient for a hydraulic cylinder having one piston, but this is very troublesome for a multi-stage hydraulic cylinder having a large number of pistons. In addition, there is a large amount of oil leakage when bleeding air. In particular, in a single-acting multi-stage hydraulic cylinder having a structure in which the pressure oil chambers of each cylinder are isolated, it takes time for the air to reach the end block, and it takes a long time to bleed the air. The present invention solves such a problem and, in short, prevents air from being introduced from the beginning at the time of pipe replacement or the like.

[0004]

Under the above problems, the present invention forms a pressure oil introducing circuit for introducing pressure oil to the head side block of the basic cylinder constituting the multistage hydraulic cylinder device, and at the same time, introduces the pressure oil. A pressure oil supply circuit that supplies pressure oil from the circuit to the multi-stage hydraulic cylinder device and an air vent circuit that communicates with the outside are branched, and the pressure oil introduction circuit and the pressure oil supply circuit or the air vent circuit can be selectively placed at this branch point. An air bleeding structure for a multi-stage hydraulic cylinder device is provided, which is provided with a switching valve that communicates.

[0005]

When the piping work is performed by the above means, first, the switching valve is switched to connect the pressure oil introduction circuit and the air bleeding circuit (at this time, the pressure oil supply circuit is blocked). Plumb with. Next, if the pressure oil is made to flow into the air venting circuit when the piping is completed, the air contained in the piping system will escape together with some pressure oil. Finally, if the switching valve is switched so that the pressure oil introduction circuit and the pressure oil supply circuit are communicated with each other, the pressure oil supplied to the multi-stage hydraulic cylinder device does not contain air.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a partial cross-sectional view of a multi-stage hydraulic cylinder device according to an embodiment of the present invention when contracted, and FIG. 2 is a partial cross-sectional view of the same when extended.
The first piston 12 is attached to the base (first) cylinder 10 at the outermost periphery.
And the second cylinder 14 integrated with this is incorporated,
A second piston 16 and a third cylinder 18 integrated with the second piston 16 are incorporated in the second cylinder 14,
4 shows a multi-stage hydraulic cylinder of four stages for convenience in which a third piston 20 and a rod 22 integrated with the third piston 20 are incorporated (the number of stages is an example, and the present invention is not limited to this. Absent).

A head-side block 24 is provided at the base end of the first cylinder 10 (this multistage hydraulic cylinder device is used as it stands upright, and is therefore the lower end). Supply to the positive pressure chamber 26.
Incidentally, rod-side blocks 28, 30, 32 are provided at the upper ends of the first to third cylinders 10, 14, 18, respectively.

When pressure oil is supplied to the positive pressure chamber 26 of the first cylinder 10, the first piston 12 is pushed up. In this case, the first piston 12 and the second piston 16 are pushed.
On-off valve 3 for introducing pressure oil to the end side cylinder respectively
4, 36 are provided, and the space between the first cylinder 10 and the second cylinder 14, that is, the back pressure chamber 38 of the first cylinder 10 (hereinafter, the same applies to the second cylinder 14 and the third cylinder 18). (The structure has the same name) and the positive pressure chamber 40 of the second cylinder 14 and the back pressure chamber 42 of the second cylinder 14.
Communication passages 48, 50, 52 are formed in the positive pressure chamber 44 and the back pressure chamber 46 of the third cylinder 18, respectively.

Therefore, the pressure oil supplied to the positive pressure chamber 26 of the first cylinder 10 passes through the on-off valves 34 and 36, the back pressure chamber 38 of the first cylinder 10, the back pressure chamber 42 of the second cylinder 14, and the second pressure chamber. The back pressure chamber 46 of the three cylinder 18 is filled. When the back pressure chambers 38, 42, 46 are filled with pressure oil (the back pressure chambers 38, 42, 46 are appropriately provided with an air bleeding structure), the first piston 12 is pushed up. Since the volume of the back pressure chamber 38 of the first cylinder 10 is reduced by a certain amount, that much pressure oil flows through the communication passage 48 to the positive pressure chamber 40 of the second cylinder 14 and pushes up the second piston 16. .

Thereafter, the third piston 20 and the rod 22 are pushed up by the same action. At this time, the volumes of the chambers through which the pressure oil flows in and out are adjusted so that the cylinders extend at a constant speed. It will be referred to as a dynamic multi-stage hydraulic cylinder (however, as described above, the present invention is not limited thereto).

The on-off valves 34 and 36 are provided with through holes 54 formed in the upper and lower portions of the first and second pistons 12 and 16, respectively.
56 has funnel-shaped spools 66, 68 which are elastically struck downward by springs 62, 64 stretched between the spring-loaded plates 58, 60. Communication holes 70, 72, 74 and 76 are formed in 66 and 68, respectively.

Accordingly, the spools 66 and 68 are the springs 62,
When it is pushed down by 64 and descends and hits the wall surface of the through holes 54 and 56, the communication holes 74 and 76 are closed to block the flow of pressure oil, but when the spools 66 and 68 rise and move away from the wall surface, the pressure oil Allow distribution of. The lower ends of the spools 66 and 68 slightly project from the lower ends of the first and second pistons 12 and 16, respectively.
When 6 descends and hits the lower member, the spools 66, 6
No. 8 is relatively elevated to allow the pressure oil to flow.

Therefore, the on-off valves 34 and 36 are
First, each back pressure chamber 3 of the first and second cylinders 10 and 14
It can be said to fill the pressure oils 8 and 42 with each other and to push up the first and second pistons 12 and 16 slightly at the initial stage of extension to sufficiently secure the pressure receiving area.

FIG. 1 shows a head side block 24 according to the present invention.
2 is a sectional side view, and FIG. 2 is a sectional side view. The head side block 24 has an external pressure oil supply device (not shown).
A pressure oil introducing circuit 78 for introducing the pressure oil supplied from is formed, and the pressure oil supplying circuit 8 communicates with the pressure oil introducing circuit 78 and supplies the pressure oil to the positive pressure chamber 26 of the first cylinder 10.
0 and an air vent circuit 82 communicating with the outside are formed in a branched manner. Then, at the branch point, the pressure oil introduction circuit 7
8 is provided with a switching valve 84 that selectively connects the pressure oil supply circuit 80 or the air bleeding circuit 82.

Although there are various structures of the switching valve 84, in this example, the switching valve insertion path 86 is formed at the radial center of the head side block 24, and at the same time, at the same time at the radial center thereof. The pressure oil introducing circuit 78 is formed in the above, and the pressure oil supplying circuit 80 and the air bleeding circuit 82 are formed at positions eccentric to the pressure oil introducing circuit 78. Then, the pressure oil supply circuit 80 and the air vent circuit 82 in the switching valve insertion path 86.
A spool type switching valve 84 consisting of a valve head 84a and a valve rod 84b is inserted between and.

A cap 8 is provided at the end of the switching valve insertion passage 86.
8, the push screw 90 is screwed into the cap 88, and the valve rod 84b is pushed by pushing and pulling the push screw 90 to move the valve head 84a to both sides of the pressure oil introducing circuit 78 ((a) in FIG. 1 and the like). And (b) position).

As described above, when connecting the multi-stage hydraulic cylinder device to the pressure oil supply device, first, the switching valve 84 is set to the position (a) to close the pressure oil supply circuit 80, and the pipes are connected in this state. . When piping is completed, switching valve 84
The pressure oil is introduced into the pressure oil introduction circuit 78 while keeping the position as it is. Then, the air mixed in the pipe goes out from the air vent circuit 82 together with some pressure oil, so after confirming that the air has escaped, return the switching valve 84 to the position (b) to perform the air vent operation. Ends.

[0018]

As described above, according to the present invention, when the multi-stage hydraulic cylinder device is installed as an actual machine, the air mixed in the pressure oil can be extracted only by operating the switching valve. Therefore, it is not necessary to perform the troublesome air bleeding work which takes a long time as in the conventional case.

[Brief description of drawings]

FIG. 1 is a sectional rear view of a head-side block showing an embodiment of the present invention.

FIG. 2 is a sectional side view of a head-side block showing an embodiment of the present invention.

FIG. 3 is a sectional view showing a shortened state of the multi-stage hydraulic cylinder device.

FIG. 4 is a cross-sectional view showing an extended state of the multi-stage hydraulic cylinder device.

[Explanation of symbols]

 10 basic (first) cylinder 24 head side block of basic cylinder 78 pressure oil introduction circuit 80 pressure oil supply circuit 82 air bleeding circuit 84 switching valve

Claims (1)

[Claims] 1. A pressure oil which forms a pressure oil introduction circuit for introducing pressure oil into a head side block of a main cylinder constituting a multi-stage hydraulic cylinder device, and supplies pressure oil from the pressure oil introduction circuit to the multi-stage hydraulic cylinder device. A multi-stage hydraulic pressure characterized by branching a supply circuit and an air vent circuit communicating with the outside, and providing a switching valve at this branch point for selectively communicating the pressure oil introduction circuit with the pressure oil supply circuit or the air vent circuit. Cylinder device air bleeding structure.