JP2535972Y2 - Air cylinder with drop prevention device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cylinder provided with a device for preventing a piston from falling.

[0002]

2. Description of the Related Art For example, a cylinder used as a drive for moving a workpiece in a vertical direction is provided with a piston drop prevention mechanism for safety. As a cylinder with a fall prevention device having such a device,
For example, there is one proposed in Japanese Utility Model Laid-Open Publication No. 61-16412. This air cylinder is for vertically conveying a work supported on the lower end of a piston rod. In this air cylinder, when air is supplied from the supply / discharge port to the lower chamber and air in the upper chamber is exhausted from the supply / discharge port via a check valve, the piston is moved upward. When the engagement protrusion of the plunger provided on the head cover engages with the annular groove formed at the upper end of the piston rod, the piston is locked at the raised end position and does not move.

When air is supplied to the supply / discharge port to supply air to the upper chamber, air is sent into the plunger chamber, and the plunger is moved in a direction away from the piston against the urging force of the spring. Then, the engagement of the engagement projection with the annular groove is released, and the piston can move downward.

[0004]

However, there is a possibility that the leaked air is gradually discharged from the air supply source, and the plunger is inadvertently moved in the unlocking direction by the pressure caused by the air. In such a situation, there is a danger that the work supported by the piston of the cylinder may drop unexpectedly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object a simple structure, and an air with a fall prevention device which can securely lock and hold a piston even if leakage air occurs. To provide a cylinder.

[0006]

In order to achieve the above object, according to the present invention, a locked portion protruding from a piston is provided.
A storage chamber is formed in the cylinder case so as to communicate with the cylinder chamber, and a storage chamber for storing the locked portion when the piston is located at one of the moving ends, and a position where the locked portion of the storage chamber is engaged with the locked portion, and A lock member movable between a position in which the piston is released and an air supplied to the cylinder chamber through the storage chamber, and the piston is immovably locked by engaging the lock member with the locked portion. Air cylinder with a fall prevention device
The cylinder case or the lock member is formed with a slit for releasing the pressure in the storage chamber to the atmosphere, and the slit is arranged so that the slit is closed by the lock member disposed at the release position. The gist is that they did.

[0007]

Therefore, according to the structure of the present invention, when the piston is located at one of the moving ends, the lock member is engaged with the piston rod. At this time, the slit is opened and the pressure in the storage chamber is released, and the air pressure in the storage chamber does not increase.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
A description will be given based on FIG. As shown in FIG. 1, a head cover 2 and a rod cover 3 are fitted and fixed to the upper and lower ends of a cylinder tube 1, respectively, to form a cylinder case as a whole. A piston 4 slidably inserted into the cylinder tube 1;
It comprises a piston rod 6 fixed to the piston head 5 and projecting downward through the rod cover 3. An upper chamber R1 and a lower chamber R2 are formed in the cylinder tube 1 by the piston head 5. A work W is suspended from the lower end of the piston rod 6.

Further, a housing hole 7 as a housing chamber capable of housing the upper end of the piston rod 6 is provided in the head cover 2,
A plunger chamber 8 that is substantially orthogonal to the accommodation hole 7 is formed, and the accommodation hole 7 and the upper chamber R1 communicate with each other, and the accommodation hole 7 and the plunger chamber 8 communicate with each other through a small hole 9. A plunger 10 serving as a lock member is slidably inserted into the plunger chamber 8, and the plunger 10 is urged by a spring 11 in a direction approaching the axis of the cylinder tube 1 (to the right in FIGS. 1 to 4). ing. At the tip of the plunger 10, an engagement projection 12 is formed to pass through the small hole 9, and the engagement projection 12 projects into the accommodation hole 7 when the plunger 10 is located on the right side.

The plunger chamber 8 is divided by the plunger 10 into a right chamber 13 and a left chamber 14. Left ventricle 14
The right chamber 13 communicates with a supply / discharge port 16 formed in the head cover 2 through a passage 17 through an exhaust hole 15 provided at the end of the chamber. When air is supplied from the supply / discharge port 16 via the passage 17, the plunger 10 moves away from the axis of the cylinder tube 1 against the urging force of the spring 11 (to the left in FIGS. 1 to 4). Be moved. A narrow gap 18 is formed in the head cover 2 to communicate the right chamber 13 and the left chamber 14. The slit 18 is configured to be opened only when the plunger 10 is located on the right side, and to be closed by the plunger 10 when the plunger 10 is located on the left side.

The engagement projection 12 of the plunger 10 has
A through hole 19 is formed at the tip and the peripheral surface. When the plunger 10 is located at the right position as shown in FIGS. 1 and 2, the opening on the peripheral surface side of the through hole 19 is closed by the peripheral surface of the small hole 9, and the plunger chamber 8 and the accommodation hole are closed. When the communication with the valve 7 is cut off and the plunger 10 is located at the left position, the opening on the peripheral surface of the through hole 19 is opened in the plunger chamber 8 and the opening on the distal end is opened in the receiving hole 7. As a result, the plunger chamber 8 and the accommodation hole 7 communicate with each other.

The tip of the piston rod 6 has a conical surface 2
0 is formed, and below the conical surface 20, an annular groove 21 is formed as a locked portion to which the engagement protrusion 12 of the plunger 10 can be engaged. A check valve 22 that allows air to flow only in the direction from the housing hole 7 to the supply / discharge port 16 is interposed between the housing hole 7 and the supply / discharge port 16. The rod cover 3 is formed with a supply / discharge port 23 communicating with the lower chamber R2. The supply / discharge ports 16 and 23 formed in the head cover 2 and the rod cover 3 are connected to a three-position five-port switching valve 26 via passages 24 and 25, respectively. Further, speed control valves 27 and 28 are interposed on the passages 24 and 25, and control the piston speed by adjusting the flow rate of air.

Next, the operation of the air cylinder configured as described above will be described. Now, the three-position five-port switching valve 26
Is switched to the position a, the air from the air supply source 29 is sent into the lower chamber R2 via the passage 25 and the supply / discharge port 23, and the piston 4 is moved upward while the work W is suspended. The air in the upper chamber R1 is exhausted through the supply / discharge port 16 and the passage 24 via the check valve 22. At this time, the plunger 10 is located on the right side by the urging force of the spring 11, and the air in the upper chamber R1 does not leak out from the through hole 19 to the outside. The slit 18 communicating the right chamber 13 and the left chamber 14 of the plunger chamber 8 is open, but its diameter is extremely small and leakage does not matter. Immediately before the piston 4 is located at the rising end, the conical surface 20 at the upper end of the piston rod 6 engages with the tip of the engaging projection 12 to move the plunger 10 to the left against the urging force of the spring 11. .
When the piston 4 is located at the rising end, the plunger 10 moves to the right by the urging force of the spring 11 as shown in FIGS. The piston 4 is locked and stopped at that position.

At this time, the slit 18 is open, and the upper chamber R1 contains the accommodation hole 7, the supply / discharge port 16, the passage 17, the right chamber 13 of the plunger chamber 8, the slit 18, and the left chamber 1 of the plunger chamber 8.
4. Open to the atmosphere through the exhaust hole 15. Therefore, when the piston 4 is located at the rising end, the three-position five-port switching valve 2
6 is immediately switched to the "b" position.
Although the supply and exhaust of air to 3 are shut off and the air is not exhausted, the air in the upper chamber R1 is reliably exhausted from the exhaust hole 15 and no air pressure remains in the upper chamber R1. That is, there is no possibility that the plunger 10 is moved to the left by being pressed by the residual pressure of the air, and the engagement of the engagement protrusion 12 with the annular groove 21 is securely held.

If the air in the lower chamber R2 leaks from the space between the piston head 5 and the cylinder tube 1 into the upper chamber R1, or if air leaks from the air supply source 29 to the passage 1,
Even if the air enters the inside, the leaked air is exhausted from the exhaust hole 15 through the narrow gap 18 as described above, and does not act on the plunger 10 to the left, that is, in the unlocking direction. Accordingly, the engagement of the engagement protrusion 12 with the annular groove 21 does not come off due to the leakage air,
Locked state can be maintained.

Next, when the three-position five-port switching valve 26 is switched to the position c in this state, the air from the air supply source 29 flows through the passage 24 and the supply / discharge port 16 to the plunger chamber 8.
Sent inside. At this time, the slit 18 is open, but since the air flow rate from the air supply source 29 is sufficiently larger than the flow rate exhausted from the slit 18, the plunger 10 is
3 is moved to the left side position as shown in FIG. Then, the engagement of the engagement protrusion 12 with the annular groove 21 is released, and the piston 4 can move downward. Then, when the plunger 10 is moved to the left position, the slit 18 and the exhaust hole 15 are closed by the plunger 10, and the air from the supply / discharge port 16 and the check valve 22 flows into the accommodation hole 7 and the upper chamber R1. And the piston 4 is moved downward. Then, the air in the lower chamber R2 is exhausted through the supply / discharge port 23 and the passage 25.

As described above, in the air cylinder with the drop prevention device, when the piston 4 is in the locked state, the leaked air is discharged to the atmosphere through the narrow gap 18, and the lock is not released by the leaked air. There is no danger that the work W may drop unexpectedly.

In addition, the configuration for this is very simple because only the slit 18 is provided. Therefore, the possibility of failure and malfunction can be extremely reduced. In addition, this invention is not limited to the said Example, It is also possible to embody in the following aspects.

(1) In the above-described embodiment, the narrow gap 18 communicating the right chamber 13 communicating with the supply / discharge port 16 and the left chamber 14 communicating with the atmosphere is formed in the head cover 2, but as shown in FIG. A slit 31 may be formed in 30 itself.
When the plunger 30 is located on the right side, the slit 31 is opened and the air in the upper chamber R1 is discharged. Plunger 30
Is located on the left side, the end of the slit 31 abuts against the wall of the plunger chamber 8 and the slit 31 is closed. Therefore, the air pressure in the upper chamber R1 is maintained. The method of providing the slit 31 in the plunger 30 is easy to form, and can reduce the number of steps and the cost.

(2) The slit 32 is directly connected to the passage 17 as shown by a two-dot chain line in FIG.

[0021]

According to the present invention, as described in detail above, an excellent effect is obtained in that the structure is simple and the piston can be securely locked at the rising end position.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an air cylinder with a fall prevention device embodying the present invention.

FIG. 2 is an enlarged view of a main part showing one embodiment of an air cylinder with a fall prevention device.

FIG. 3 is an enlarged view of a main part showing one embodiment of an air cylinder with a fall prevention device.

FIG. 4 is an enlarged view of a main part showing another example of the air cylinder with the fall prevention device.

[Explanation of Signs] 1 Cylinder tube constituting cylinder case, 2
A head cover forming a cylinder case, a rod cover forming a cylinder case, a piston, a receiving hole serving as a receiving chamber, a plunger serving as a locking member, an annular groove serving as a locked portion;

Claims (1)

(57) [Scope of request for utility model registration] 1. A locked portion protruding from a piston, and a cylinder case formed to communicate with a cylinder chamber,
A housing chamber for housing the locked portion when the piston is located at one of the moving ends, and a lock member movable between a position where the piston is engaged with the locked portion of the housing room and a position where the piston is disengaged therefrom. Air is supplied into the cylinder chamber through the storage chamber, and the air cylinder with a fall prevention device is configured such that the piston is immovably locked by engaging the lock member with the locked portion. The cylinder case or the lock member is formed with a slit for releasing the pressure in the storage chamber to the atmosphere, and the slit is arranged so that the slit is closed by the lock member disposed at the release position. An air cylinder with a fall prevention device.