JPH0534876Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to the operating part of equipment, such as a press machine, which reciprocates in the direction of gravity and in the direction of anti-gravity by means of fluid pressure such as hydraulic pressure or pneumatic pressure. This relates to a device that prevents the vehicle from falling naturally due to its own weight.

[Conventional technology]

For example, as shown in FIG. 3, cylinder a,
a piston b that is in close contact with the inner circumferential surface of the cylinder a;
It has a piston rod c extending vertically from the piston b and penetrating the lower end wall of the cylinder a, and by switching the pressure from the pressure source g to the chambers e and f on both sides of the piston b in the cylinder a with a directional control valve h. , in a device that reciprocates a workpiece d interlocking with the piston b via a piston b and a piston rod c up and down, when the operating part consisting of the piston b, the piston rod c, the workpiece d, etc. is stopped at the upper part of the stroke, There is a problem in that the operating part gradually descends due to its own weight. In other words, the reason why such a drop due to its own weight occurs is that the seal i is interposed between the cylinder a and the piston b, and the seal j is interposed between the shaft hole of the cylinder a and the piston rod c to seal the chambers e and f. However, it is difficult for these gaskets i and j to completely block even the slightest leak of pressurized fluid from chamber f, which is pressurized to support piston b in a fixed position. This is because there is also leakage from the control valve h.

For this reason, conventionally, as shown in FIG. 4, by incorporating a pilot check valve k into the pressure circuit between the cylinder a and the directional control valve h, the fluid in the chamber f leaks from the directional control valve h. This prevents it from being stowed away and minimizes the natural descent of the moving parts due to their own weight.

[Problem that the invention attempts to solve]

However, the pilot check valve k does not solve the problem of leakage from the gaskets i and j, and it is impossible to completely eliminate the leakage of the pilot check valve k itself. A descent due to its own weight was occurring.

[Means for solving problems]

Therefore, in order to solve the above problem, the present invention provides a support pressure that extends from the pressure source into the cylinder through the shaft hole through which the piston rod extending from the piston is hermetically inserted, and supplies pressure to support the piston against gravity. In addition to providing a supply path, the piston rod is provided with a communication port that connects the support pressure supply path only when the piston is at a predetermined position.

[Effect]

In other words, by switching the pressure applied from the pressure source to the chambers on both sides of the piston, the piston is pushed up in the anti-gravity direction, and the communication port formed in the piston rod linked to this lifts the height at which the support pressure supply path communicates with the piston. If the piston and piston rod are stopped at a position higher than the above position, even if the moving parts including the piston and piston rod naturally descend due to their own weight, the support A pressure that supports the piston in an anti-gravity direction is applied from a pressure source into the cylinder via the pressure supply path, and the piston is pushed up by the pressure. As the communication port of the piston rod also rises, the support pressure supply path is cut off, and the pressure supply to the cylinder is cut off, causing the piston to stop. When the weight of the piston falls, the support pressure supply path becomes conductive again due to the fall of the communication port, so that pressure is supplied into the cylinder, and by repeating this process, the piston is held in place.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which 1 is a cylinder, 2 is a piston that is in close contact with the inner peripheral surface of the cylinder 1 via a packing 12, and 3 is a shaft hole 5 in the lower end wall of the cylinder 1. The piston rod is hermetically inserted through a gasket 13, and its upper end is fixed to the piston 2, and its lower end is connected to a workpiece 4 outside the cylinder 1. ,
It is capable of reciprocating vertically with respect to the cylinder 1.

Pressure from a pressure source 9 is supplied to the upper and lower chambers 6 and 7 of the piston 2 in the cylinder 1 through a directional control valve 10 that is activated by an electric signal to the solenoids 11a and 11b to switch the pressure direction. A main circuit 8 that applies pressure is extended, that is, when the directional control valve 10 is switched to 10a, the chamber 6 is pressurized and the chamber 7 is pressurized.
is opened and the piston 2 descends; conversely, when the switch is switched to 10b, the chamber 7 is pressurized, the chamber 6 is opened, and the piston 2 rises.

Ports 17 and 18 are bored inside the lower end wall of the cylinder 1, and the inner ends thereof are located between the gaskets 14 and 15 on the inner circumferential surface of the shaft hole 5 and open. Solenoid 20 at the end
It communicates with said pressure source 9 via a conduit having a control valve 19 actuated by a port 18.
The outer end of the piston 2 communicates with the lower chamber 7 of the piston 2 via a pipe line having a check valve 21 that allows pressure fluid to flow only from the port 18 side, and these ports 17, 18, valves 19, 21 and the pipe line constitute a supporting pressure supply line 16 extending from the pressure source 9 to the chamber 7 across the shaft hole 5.

Further, at a predetermined position in the axial direction of the piston rod 3, there is an annular groove 23 that forms a communication port 22 that shuts off or connects the ports 17 and 18 of the support pressure supply path 16 as the piston rod 3 moves up and down.
is formed. 24 is the seal 1 of the shaft hole 5
This is a drain port extending from between 3 and 14 to the outside of the cylinder 1.

According to the above configuration, when the chamber 7 is pressurized and the piston 2 is pushed up, and the groove 23 of the piston rod 3 that rises with this, that is, the communication port 22 reaches the position corresponding to the inner end opening of the ports 17 and 18, The directional control valve 10 is placed in the closed position 1 as shown in the figure.
0c to stop the rise of the piston 2, and at the same time switch the control valve 19 of the support pressure supply path 16 to the conduction position 19a, the communication port 22 conducts the ports 17 and 18, in other words, the support pressure supply path 16. Therefore, pressure is supplied from the pressure source 9 to the chamber 7 via the supply path 16, and the piston 2
will rise. Then, as the communication port 22 also rises in conjunction with the piston 2, the connection between the ports 17 and 18 is eventually cut off, that is, the pressure supply from the pressure source 9 to the chamber 7 is cut off, and the check valve 21 is closed. state. Here, Patsukin 12,
If the pressurized fluid in the chamber 7 leaks from the directional control valve 13 or the directional control valve 10 and the piston 2 descends even slightly due to the weight of the operating part, the communication port 22, which descends in conjunction with this, again passes between the ports 17 and 18. Because of this, the support pressure supply path 16 is immediately connected to the chamber 7.
Pressure is now supplied to. In other words, the communication port 22 that interlocks with the piston 2 automatically repeats the connection and disconnection of pressure to the chamber 7, and the piston 2 is maintained at a constant height.

Next, FIG. 2 shows another embodiment of the present invention, and the difference from the above embodiment is that the piston rod 3 extends perpendicularly from both the upper and lower end surfaces of the piston 2 and penetrates the cylinder 1 vertically. The rod 3 protrudes from the shaft hole 5b in the lower end wall of the cylinder 1.
A workpiece 4 is attached to the lower end. Further, the upper part 3' of the rod 3 that protrudes upward from the shaft hole 5a in the upper end wall of the cylinder 1
It is inserted into the shaft hole 5 of a slide member 26 mounted on the top via a bracket 25 in a height-adjustable manner. Ports 17 and 18 forming part of the support pressure supply path 16 extending from the pressure source 9 to the chamber 7 below the piston 2 in the cylinder 1 are
The slide member 26 is provided with this port 1.
Communication port 22 for conducting/blocking between 7 and 18
The annular groove 23 as shown in FIG.
It is formed at an appropriate position on the upper part 3' of the. 13a, 13b are the shaft holes 5a, 5 of the cylinder 1.
This is a gasket that is attached to the piston rod 3 to maintain airtightness with the piston rod 3.

This embodiment has a major feature in that the supporting position of the piston 2 can be changed to any height within the stroke range, that is, by changing the fixed position of the slide member 26 relative to the bracket 25 up or down. Tute port 17, 18
By changing the height of
It is possible to change the equilibrium position of the piston 2 by repeating the interruption.

In each of the above embodiments, the communication port 22 is formed by the groove 23, but it may also be formed by drilling a hole.

[Effect of idea]

As mentioned above, the present invention provides a communication port that interlocks with the piston and a support pressure supply path that supplies pressure to support the piston against gravity, so that the piston can reach a predetermined level by the weight of the operating part including the piston. By having a structure in which the communication port conducts the support pressure supply path when it descends to a certain position, and shuts it off when it rises above a predetermined position, the piston (operating part) is automatically balanced at a certain position. It is possible to completely prevent the moving parts from falling due to their own weight, improving safety and preventing equipment damage. It has the feature that the support position can be changed arbitrarily by changing the .

[Brief explanation of the drawing]

FIG. 1 is a schematic structural explanatory diagram showing one embodiment of the present invention, FIG. 2 is a schematic structural explanatory diagram showing another embodiment,
3 and 4 are schematic structural explanatory diagrams showing a conventional example. 1... Cylinder, 2... Piston, 3... Piston rod, 4... Work, 5, 5a, 5b...
Shaft hole, 6, 7... Chamber, 8... Main circuit, 9... Pressure source, 10... Directional control valve, 11a, 11b, 20
...Solenoid, 12, 13, 13a, 13b,
14, 15...Packing, 16...Support pressure supply path, 17, 18...Port, 19...Control valve, 2
1...Check valve, 22...Communication port, 23...
...Groove, 24...Drain port, 25...Bracket, 26...Slide member.

Claims (1)

[Scope of utility model registration request] In a device that reciprocates in the direction of gravity and in the direction of anti-gravity by switching the pressure applied to the chambers 6 and 7 on both sides of the piston 2 in the cylinder 1, the piston rod 3 extending from the piston 2 is inserted into the shaft hole 5 in an airtight manner. A support pressure supply path 16 is provided which extends from the pressure source 9 into the cylinder 1 via the pressure source 9 and supplies pressure to support the piston 2 against gravity, and the support pressure is applied only when the piston 2 is at a predetermined position. Communication port 2 that connects the supply path 16
2 is provided on the piston rod 3. A device for preventing descent due to its own weight.