JP2659163B2 - Fluid pressure 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 a hydraulic cylinder provided with a fall prevention device for preventing a piston from falling.

[0002]

2. Description of the Related Art In general, in a fluid pressure cylinder, a piston rod provided so as to be able to protrude and retract from a cylinder case is directed downward, and a work is supported at a lower end of the piston rod, so that the work is vertically transferred. May be used for Such a fluid pressure cylinder is provided with a fall prevention device to prevent the piston rod from falling under its own weight when the fluid pressure cylinder is not operated.

[0003] Conventionally, as this type of fluid pressure cylinder with a fall prevention device, there is one as shown in FIG. That is, the fluid pressure cylinder supports the work W at the lower end of the piston rod 31 movably provided with respect to the cylinder case 30. The fluid is supplied from the supply / discharge port 32 into the lower chamber R2, and the fluid in the upper chamber R1 is supplied from the supply / discharge port 33.
When exhausted from the piston, the piston 34 is moved upward.

An annular groove 35 is formed in the upper part of the piston rod 31, and a rod-shaped plunger 38 is provided in a plunger chamber 37 projecting from a side of the head cover 36.
Are accommodated so as to be movable in a direction orthogonal to the piston rod 31. When the plunger 38 moves toward the piston rod 31 (to the right in FIG. 6) based on the urging force of the spring 39 disposed in the plunger chamber 37, the plunger 38 is formed at the tip of the plunger 38 in the annular groove 35. The engagement projection 40 is engaged, and the piston 34 is locked at its raised end position so as not to move.

When fluid is supplied to the supply / discharge port 33 of the upper chamber R 1, the fluid is sent into the plunger chamber 37, and the plunger 38 resists the urging force of the spring 39 to move the piston rod 3.
It is moved in a direction away from the position 1 (to the left in FIG. 6). As a result, the engagement of the engagement projection 40 with the annular groove 35 is released, and the piston 34 moves downward.

[0006]

By the way, in recent years, with the miniaturization of various industrial machines, the installation space for the fluid pressure cylinder has been limited, and the fluid pressure cylinder itself has been reduced in size.

However, the above-mentioned conventional hydraulic cylinder with a drop prevention device is provided with a rod-shaped plunger 38 which moves perpendicularly to the axial direction of the piston rod 31, and the plunger 38 and the plunger chamber 37 are arranged in a cylinder case. It has a shape protruding from 30. As a result, the provision of the fall prevention device has been an obstacle to downsizing the fluid pressure cylinder itself.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate the protrusion of a cylinder case based on a fall prevention device outside the cylinder case without increasing the size of the cylinder case itself, thereby reducing the size and space. It is another object of the present invention to provide a fluid pressure cylinder with a fall prevention device which can achieve the following.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a supply / discharge port for movably providing a piston in a cylinder case and supplying and exhausting fluid to two chambers partitioned by the piston. The piston is movable by selectively supplying a fluid to these supply / discharge ports, and furthermore, a locking member provided on the fall prevention device is engaged with an engaging portion formed on the piston side . By this, in a fluid pressure cylinder with a drop prevention device that stops and holds the piston at a predetermined position in the cylinder case,
An annular groove is formed in the inner peripheral wall of the cylinder case, and the groove is formed.
A resilient ring is accommodated in the groove along the groove.
By disposing the locking member on the inner peripheral side of the ring,
Constitutes a lowering prevention device, by the elastic force of the ring
Normally, the locking member is urged toward the engaging portion, and the
By supplying a pressurized fluid to the area on the inner circumference side of the ring.
The diameter of the ring expands, and the engagement between the locking member and the engaging portion is released.
The gist is that it is removed .

[0010]

According to the present invention, by adopting the above means,
Engagement of the locking member and the engaging portion for preventing fall and the solution thereof
A groove and a ring to be housed in the groove.
And the groove is formed on the inner peripheral wall of the cylinder case.
The structure of the fall prevention device is extremely simple
It can be simplified to achieve compactness and space saving.
It is possible to reduce the cost as well as possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to 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 the cylinder tube 1, respectively, and the cylinder tube 1, the head cover 2 and the rod cover 3 constitute a cylinder case. The piston 4 is a piston head 5 slidably inserted into the cylinder tube 1.
And the rod cover 3 fixed to the piston head 5
And a piston rod 6 protruding downward through the hole. The interior of the cylinder tube 1 is partitioned into an upper chamber R1 and a lower chamber R2 by the piston head 5. A work W is suspended from the lower end of the piston rod 6.

The head cover 2 is formed with a housing recess 7 having a diameter slightly larger than the outer diameter of the piston rod 6 so that the upper end of the piston head 6 can be housed. The head cover 2 is formed with a storage recess 7, that is, a supply / discharge port 8 communicating with the upper chamber R1, and the rod cover 3 is formed with a supply / discharge port 9 communicating with the lower chamber R2.

The two supply / discharge ports 8 and 9 are connected to the passage 1 respectively.
The fluid supply source S is connected to the three-position five-port switching valve 12 via 0,11.
Is supplied in a switching manner. Speed control valves 13 and 14 are interposed on the passages 10 and 11, respectively, and the flow rate of the fluid is adjusted by these two speed control valves 13 and 14 to control the piston speed.

Next, the structure of the fall prevention device 15 will be described. A groove 16 is formed on the inner peripheral wall of the head cover 2 so as to extend along the inner periphery of the housing recess 7. A communication hole 17 communicating with the groove 16 is formed at one location in the head cover 2 and the cylinder tube 1. A retainer ring 18 as an urging member made of an elastic material is fitted into the groove 16 to cut off communication between the upper chamber R1 and the outside air through the insertion hole 17. In addition, retainer ring 18
Various known elastic materials such as urethane rubber and nitrile rubber can be used.

Balls 19 serving as locking members are fixed to the inner circumference of the retainer ring 18 at three positions at 120-degree intervals (see FIG. 3), and are accommodated in the grooves 16. As shown in FIG. 2, a protrusion 20 is formed in the upper chamber R1 side opening of the groove 16 so as to protrude inward so that the opening of the groove 16 is slightly narrower than the diameter of the ball 19. From the groove 16 is prevented. Therefore, as the pressure in the upper chamber R1 becomes higher than the external pressure, the retainer ring 18
Is expanded against the elastic force so that each ball 19 is completely accommodated in the groove 16. Conversely, upper room R
As the pressure inside 1 becomes lower than the outside air pressure, the diameter of the retainer ring 18 is reduced by its elastic force, so that each ball 19 comes into contact with the ridge 20. In this state, approximately half of each ball 19 is projected into the accommodation recess 7 respectively.

The upper end of the piston rod 6 has a conical surface 2
An annular groove 22 is formed below the conical surface 21 as an engaging portion with which the balls 19 can be engaged at the rising end position of the piston 4.

The groove 16, the retainer ring 18 and the ball 19 constitute a fall prevention device 15. Therefore, the fall prevention device 15 has a structure completely incorporated in the head cover 2.

Next, the operation of the air cylinder configured as described above will be described. Now, a 3-position 5-port switching valve 12
Is switched to the position a, the fluid from the fluid supply source S is sent into the lower chamber R2 via the passage 11 and the supply / discharge port 9, and the piston 4 is moved upward while the work W is suspended. The fluid in the upper chamber R1 is supplied to the supply / discharge port 8 and the passage 10
Exhausted through. At this time, the pressure in the upper chamber R1 is almost equal to the outside air pressure. As a result, the diameter of the retainer ring 18 is reduced by the elastic force of the retainer ring 18 while maintaining the airtight state with respect to the groove 16. And each ball 1
9 are in contact with the ridges 20, and approximately half of each ball 19 is projected into the accommodation recess 7 respectively.

Immediately before the piston 4 is located at the rising end, each ball 1 is placed on the conical surface 21 at the upper end of the piston rod 6.
9 abuts and retreats the ball 19 along the surface of the conical surface 21 while expanding the diameter of the retainer ring 18 against its elasticity. Thereafter, when the piston 4 reaches the rising end, the diameter of the retainer ring 18 is reduced again, so that the ball 1
9 engages with the annular groove 22 and the piston 4 is locked and stopped at that position.

At this time, when the 3-position 5-port switching valve 12 is switched to the position b, the supply and exhaust of the fluid to the supply / discharge ports 8 and 9 are shut off. However, the diameter of the retainer ring 18 is reduced even in this state. Each ball 19
Engagement with the annular groove 22 is securely held.

Next, when the 3-position 5-port switching valve 12 is switched from this state to the position c, the fluid from the fluid supply source S is sent into the upper chamber R1 through the passage 10 and the supply / discharge port 8. At this time, the pressure in the upper chamber R1 becomes higher than the outside air pressure, the diameter of the retainer ring 18 expands, and each ball 19 is completely accommodated in the groove 16. As a result, the engagement of each ball 19 with the annular groove 22 is released, and the piston 4 located at the rising end is moved downward.

Therefore, according to the present embodiment, since the fall prevention device 15 is completely incorporated in the head cover 2, it protrudes outside the cylinder tube 1 without increasing the size of the cylinder tube 1 itself. Can be eliminated. As a result, the fluid pressure cylinder with the fall prevention device can be made compact and space-saving.

In addition, the groove 16 and the retainer ring 18
Since the fall prevention device 15 can be constituted by the ball 19 and the ball 19, the number of components of the fall prevention device 15 can be reduced and the reliability for the user can be improved.

It should be noted that the present invention is not limited to the above-described embodiment, but can be carried out as follows without departing from the spirit of the present invention. (1) In the above embodiment, the protrusion 19 is formed at the opening of the groove 16 in order to prevent the ball 19 from falling out of the groove 16, but the protrusion 20 may be omitted. That is, as shown in FIG.
The groove width of the ball 6 may be fixed, and the ball 19 may be prevented from falling off only by the frictional force of the retainer ring 18 against the inner wall of the groove 16.

(2) In the above embodiment, the ball 19 is used as the locking member. However, as shown in FIG. 5, instead of the ball 19, a projection 25 whose diameter decreases toward the tip may be used. . In this case, the flange 26
By forming the protrusions 27 at the openings of the grooves 16, it is possible to prevent the protrusions 25 from falling off. Further, similarly to the above-mentioned another example, the flange 26 and the projection 2
5 may be omitted to prevent the protrusion 25 from falling off only by the frictional force of the retainer ring 18 against the inner wall of the groove 16.

(3) In the above embodiment, three balls 19 (projections 25) are provided at equal intervals. However, at least one ball 19 (projections 25) is sufficient. (4) In the above embodiment, the communication hole 17 is formed at one place. However, the communication hole 17 may be formed at two or more places, or the communication hole 17 may be omitted.

[0027]

[0028]

As described in detail above, according to the present invention,
Engagement of the locking member and the engaging portion for preventing fall and the solution thereof
A groove and a ring to be housed in the groove.
And the groove is formed on the inner peripheral wall of the cylinder case.
The structure of the fall prevention device is extremely simple
It can be simplified to achieve compactness and space saving.
It is possible to reduce the cost as well as possible.

[Brief description of the drawings]

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

FIG. 2 is a partial sectional view showing a main part of the fall prevention device.

FIG. 3 is a plan view of the fall prevention device, particularly showing a retainer ring and a ball.

FIG. 4 is a partial sectional view showing another example of the fall prevention device.

FIG. 5 is a partial sectional view showing still another example of the fall prevention device.

FIG. 6 is a longitudinal sectional view showing a conventional hydraulic cylinder with a fall prevention device.

[Explanation of symbols]

1, 2, 3 ... Cylinder tube, head cover, rod cover, 4 ... piston, 8,
9: Supply / discharge port, 15: Fall prevention device, 16: Groove as accommodation portion, 18: Retainer ring as urging member, 1
9, 25: balls and projections as locking members, 22: annular grooves as engaging portions, R1, R2: upper chamber, lower chamber.

Claims (1)

(57) [Claims] A piston (4) is movably provided in a cylinder case (1, 2, 3), and fluid is supplied and exhausted into two chambers (R1, R2) partitioned by the piston (4). A supply / discharge port (8, 9) is formed, and the piston (4) can be moved by selectively supplying a fluid to the supply / discharge port (8, 9). By engaging the locking members (19, 25) with the engaging portions (22) formed on the piston (4) side , the piston (4) is connected to the cylinder case (1, 25).
In a fluid pressure cylinder with a drop prevention device that is stopped and held at a predetermined position in (2, 3), an annular groove is formed in an inner peripheral wall of the cylinder case (1, 2, 3).
(16) is formed, and elastic grooves are formed in the grooves (16).
The ring (18) is received along the groove (16), and its ring
The locking members (19, 25) are provided on the inner peripheral side of the ring (18).
The fall prevention device (15) is configured by arranging the
Due to the elastic force of the ring (18), the locking is always performed.
The members (19, 25) are urged toward the engaging portions (22).
And pressurized fluid is supplied to a region on the inner peripheral side of the ring (18).
The ring (18) expands in diameter by supplying
The engagement between the stop members (19, 25) and the engagement portion (22) is released.
A fluid pressure cylinder with a fall prevention device.