JPH04302778A - Cushion packing for pressure cylinder - Google Patents

Abstract

PURPOSE:To prevent the packing body from abutting on the edge portion of the recessed groove and being thereby damaged, and to enhance the durability and the sealing performance by causing the packing body to be rocked via an inner protrusion 51 with the movement of a slide member, thereby causing a seal portion of the packing body to be pressure contacted with the recessed groove. CONSTITUTION:When a large-diameter portion 20a of a cushion collar 20 as a sliding member is moved in an A-indicated direction and rushes into a cushion packing 50, since an inner protrusion 51 is formed between a central part of the inner peripheral surface of a packing body 50a and a side end portion of a cushion chamber 16, the packing body 50a is radially outwardly moved and rocked. Following this, a lip-shaped seal portion 54 formed on an outer peripheral surface 53 of the packing body 50a is contacted on an inner surface of a recessed groove 12. On the other hand, the fluid in the cushion chamber 16 passes through an end face flow passage groove 57 and an outer peripheral surface flow passage groove 59 to reach a seal portion 54. In consequence, the fluid pressure acts on this seal portion 54 which in turn is pressure contacted with the inner surface of the recessed groove 12 to obtain a state of seal.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD OF THE INVENTION The present invention relates to improvements in cushion packing used in pressure cylinders such as air cylinders or hydraulic cylinders.

0002

TECHNICAL BACKGROUND OF THE INVENTION A cushion packing performs a cushioning action to smoothly reciprocate a piston rod 4 in a pressure cylinder 2 as shown in FIG. 6, for example. As shown in FIG. 6, the cushion packing 6
The cushion collars 20, 22 are installed in grooves 12, 12 formed in the rod cover 8 and head cover 10, respectively, and move inside the cushion chambers 16, 18 formed as the piston rod 4 and piston 14 reciprocate. The reciprocating movement of the piston rod 4 is cushioned by sealing by pressing against the surface of the piston rod 4 and increasing the pressure inside the cushion chambers 16 and 18. Note that in order to apply a force for reciprocating the piston rod 4 and the piston 14, ports 24 and 26 for introducing fluid pressure are formed in the rod cover 8 and the head cover 10. By introducing or extracting fluid pressure through these ports 24 and 26, a pressure difference is created before and after the piston 14, causing the piston 14 and the piston rod 4 connected thereto to reciprocate in the axial direction.

A conventional cushion packing 6 for cushioning the reciprocating movement of the piston rod 4 is disclosed in Japanese Unexamined Patent Publication No. 1-116305 and FIG.
As shown in detail in , the groove 12 is formed by attaching a metal ring 31 having an L-shaped cross section to the inner peripheral end of the head cover 10 . An inner protrusion 32 is formed on the inner circumferential surface of the packing body 6a, which has a substantially rectangular cross section and is mounted movably in the axial direction in the groove 12 on the side opposite to the cushion chamber, so as to extend continuously in the circumferential direction. There is. This packing body 6a
An end face channel groove 35 for communicating fluid in the radial direction is formed on the end face on the side of the cushion chamber. Further, a concave tapered surface 33 is formed on the end surface of the packing body 6a on the side opposite to the cushion chamber from the outer circumferential side toward the inner circumferential side. A circumferential protrusion 34 that extends continuously in the circumferential direction is formed at the outermost periphery of the tapered surface 33. Therefore, when the cushion collar 20 moves in the direction of arrow A as shown in FIG. The circumferential protrusion 34 is pressed against the inner wall of one side of the groove 12 and sealed. By sealing the gap between the cushion collar 20 and the head cover 10 with the cushion packing 6 in this way, the pressure inside the cushion chamber 16 (or 18) is increased, and the axial movement of the piston 14 at the end of the reciprocating stroke of the piston 14 is increased. It is designed to reduce the speed and provide a cushioning effect during the reciprocating movement of the piston 14.

However, in such a conventional cushion packing 6, as shown in FIG. The inward protrusion 32 of the main body 6a may fall down in the direction of arrow A. In such a case, Figure 8
As shown in FIG. 2 , the tapered surface 33 of the main body 6 a may come into contact with the edge portion 35 of the head cover 10 . This creates a gap between the circumferential protrusion 34 of the main body 6a and the inner surface of the groove 12, which may result in a seal failure. Further, due to the contact between the tapered surface 33 and the edge portion 35 of the head cover 10, the tapered surface 33 is likely to be damaged, and there is also a problem in durability.

Furthermore, as shown in FIG. 7, a circumferential protrusion 34
Since it is structurally integrated with the packing body 6a, when the packing body 6a is deformed, the circumferential protrusion 34 is also likely to be deformed accordingly. Therefore, the packing body 6a
If the circumferential protrusion 34 is attached to the groove 12 in a deformed state, the circumferential protrusion 34 may separate from the inner surface of the groove 12, resulting in poor sealing. Therefore, in the conventional cushion packing shown in FIG.
This prevents the parts from being installed while being deformed, and maintains good sealing performance. However, there is a problem in that mounting the metal L-shaped ring 31 is complicated.

Furthermore, in the conventional packing 6, as shown in FIG. 7, the inward protrusion 32 of the main body 6a is located at the end of the inner peripheral surface of the main body 6a opposite to the cushion chamber. (or 18) has a relatively small volume. Therefore, there is a problem that a relatively large amount of absorbed energy for performing a cushioning effect cannot be secured.

[0007]

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is possible to maintain good sealing performance and improve durability, as well as to eliminate the need for attaching an L-shaped member. To provide a cushion packing for a pressure cylinder, which can improve workability, maintain a relatively large amount of absorbed energy for cushioning, and thereby provide a stable cushioning effect over a long period of time.

[0008]

SUMMARY OF THE INVENTION In order to achieve this object, the cushion packing for a pressure cylinder according to the present invention is mounted so as to be movable in the axial direction in a groove extending in the circumferential direction formed in the pressure cylinder, A cushion formed by appropriately slidingly contacting the surface of a sliding contact member that reciprocates in accordance with the reciprocating movement, and being surrounded by a pressure cylinder member including the sliding contact member according to the reciprocating movement of the sliding contact member in the axial direction. A cushion packing for a pressure cylinder that seals the interior of a chamber and acts as a cushion, includes a packing body having a substantially rectangular cross section extending in the circumferential direction within the groove, and an inner circumferential surface of the packing body; an inward protrusion formed between the central portion and the end on the cushion chamber side; and a lip-shaped seal formed on the outer circumferential surface of the packing body at the end of the outer circumferential surface on the side opposite to the cushion chamber. and an end face channel groove formed on the cushion chamber side end face of the packing body so as to guide fluid in a radial direction.

According to the cushion packing according to the present invention, since the inward protrusion is formed between the center part of the inner peripheral surface of the packing body and the end part on the side of the cushion chamber, it can be used as a sliding contact member. When the cushion collar moves from the cushion chamber side to the side opposite to the cushion chamber and enters the inside of the packing body, the cushion body is moved radially outward, and the inner peripheral side of the packing body approaches the cushion chamber side and the packing body The packing body is rotated so that the outer circumferential side approaches the side opposite to the cushion chamber. Accordingly, a lip-shaped seal portion formed at the end of the outer circumferential surface of the packing body on the side opposite to the cushion chamber is pressed against the inner surface of the groove. On the other hand, the fluid in the cushion chamber flows to this lip-shaped seal portion through the channel groove. Therefore, fluid pressure acts on this lip-shaped seal portion, and the seal portion is brought into pressure contact with the inner surface of the groove to form a seal. At this time, a pressing force is applied to the lip-shaped seal part from the inner protrusion, and the easily deformable lip-shaped seal part seals, so that good sealing performance is maintained, and unlike the conventional Furthermore, since the end surface of the packing body on the side opposite to the cushion chamber does not come into contact with the edge portion of the groove, the packing is not damaged and its durability is improved compared to the prior art.

Furthermore, since the sealing is performed by a lip-shaped sealing portion that is easily deformed, the deformation of the packing body and the deformation of this lip-shaped sealing portion are unrelated. Therefore, even if the packing body is slightly deformed when the packing is attached, good sealing performance can be maintained. Therefore, the packing can be attached to the groove formed integrally with the head cover, etc., without providing a ring with an L-shaped cross section as in the conventional case. Therefore, since the ring having an L-shaped cross section is not required, the work of attaching this ring is no longer necessary, and the workability of attaching the packing can be improved, and costs can also be reduced.

Furthermore, since the inward protrusion is provided closer to the cushion chamber side, the volume of the cushion chamber can be increased compared to the conventional one, and a large amount of absorbed energy for cushioning action can be secured, resulting in improved cushioning properties. This can be further improved.

0012

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, a cushion packing for a pressure cylinder according to an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a cushion packing according to an embodiment of the present invention, FIG. 2 is a sectional view of a cushion collar inserted into the cushion packing shown in FIG. 1, and FIG. FIG. 2 is a cross-sectional view when the cushion collar is not inserted into the cushion packing shown in FIG. 1;
FIG. 4 is a view taken from arrow IV in FIG. 3. FIG.

As shown in FIG. 1, a cushion packing 50 according to an embodiment of the present invention has a concave groove extending in the circumferential direction formed in the rod cover 8 or head cover 10 of the pressure cylinder 2 as shown in FIG. 12 so as to be freely movable in the axial direction. However, in this embodiment, the groove 1
2 is integrally formed with the rod cover 8 or the head cover 10 by a flat annular portion 49, as shown in FIG.

The cushion packing 50 according to this embodiment has a packing body 50a having a substantially rectangular cross section. An inward protrusion 51 that extends continuously in the circumferential direction is integrally formed on the inner circumferential surface of the packing body 50a. This inward protrusion 51 is formed by the packing body 50a.
It is formed between the central part of the inner circumferential surface and the end on the cushion chamber 16 side, and is formed closer to the cushion chamber 16 side. As shown in FIG. 1, with respect to the height h of the cushion packing 50, the distance (m) between the top of the inward protrusion and the cushion chamber side end surface of the packing body is set to m≦0.5h. It is preferable, and more preferably, 0.3h≦m≦0.4h.

Furthermore, in this embodiment, the packing body 50
The end surface of a on the side opposite to the cushion chamber is formed into a concave tapered surface 52 from the outer circumferential side toward the inner circumferential side. Further, a lip-shaped seal portion 54 is formed on the outer peripheral end surface 53 of the packing body 50a at the end opposite to the cushion chamber. As shown in FIG. 1, this lip-shaped seal portion 54 and the tapered surface 52 are preferably formed continuously. The angle θ between this tapered surface 52 and the inner wall is 0°<θ≦3
0°, preferably 0°<θ≦5°.

Furthermore, as clearly shown in FIGS. 3 and 4, a plurality of protrusions 56 are formed at predetermined intervals on the cushion chamber side end surface 55 of the packing body 50a. An end face channel groove 57 is defined for guiding the flow in the radial direction. A plurality of protrusions 58 are also integrally formed on the outer circumferential surface 53 of the packing body 50a, thereby defining an outer circumferential surface channel groove 59 for guiding the fluid in the axial direction. It is preferable that

Next, the function of the cushion packing according to this embodiment will be explained. As shown in FIG. 2, when the large diameter portion 20a of the cushion collar 20, which also serves as a sliding contact member, moves in the direction of arrow A and enters the cushion packing 50, the inner protrusion 51 contacts the inner circumferential surface of the packing body 50a. Since the cushion body 50a is moved radially outward, the inner circumferential side of the packing body approaches the cushion chamber side, and the outer circumferential side of the packing body moves away from the cushion chamber 16. The packing body 50a is rotated so as to approach the room side. Along with this, the packing body 5
A lip-shaped seal portion 54 formed at the end of the outer circumferential surface 53 of Oa on the side opposite to the cushion chamber is pressed against the inner surface of the groove 12. On the other hand, the fluid in the cushion chamber 16 is
7 and the outer peripheral surface channel groove 59 to the lip-shaped seal portion 54 . Therefore, fluid pressure acts on this lip-shaped seal portion 54, and this seal portion
It is pressed against the inner surface of 2 and sealed. At this time, a pressing force is applied from the inner protrusion 51 to the lip-shaped seal part 54, and the easily deformable lip-shaped seal part 54 seals, so that good sealing performance is maintained, and
Since the end surface of the packing body 50a on the side opposite to the cushion chamber does not come into contact with the edge portion 35 of the groove 12 as in the conventional case, the packing is not damaged and the durability is improved compared to the conventional case.

Furthermore, since the end surface of the packing body 50a opposite to the cushion chamber is formed into a tapered surface 52, this tapered surface 52 adjusts the sealing surface pressure between the inward protrusion 51 and the cushion collar 20. , cushion chamber 16
Therefore, the pressure inside the cushion chamber 16 is gradually increased, and a large load is not applied to the cushion packing 50 at the beginning of sealing, thereby preventing the cushion packing from turning over. At the same time, the cushioning effect becomes smooth, and particularly when the reciprocating speed of the piston 14 is slow, a good cushioning effect can be obtained.

Furthermore, since the sealing is performed by the easily deformable lip-shaped seal portion 54, the deformation of the packing body 50a and the deformation of the lip-shaped seal portion 54 are unrelated. Therefore, when installing the packing, the packing body 5
Good sealing performance can be maintained even if 0a is attached with some deformation. Therefore, the packing can be attached to the groove 12 integrally formed in the head cover 10 or the like without providing a ring having an L-shaped cross section as in the conventional case. Therefore, since the ring having an L-shaped cross section is not required, the work of attaching this ring is no longer necessary, and the workability of attaching the packing can be improved, and costs can also be reduced.

Furthermore, the inner protrusion 51 is connected to the cushion chamber 16.
Since it is provided closer to the side, the volume of the cushion chamber 16 can be increased compared to the conventional one, and a large amount of absorbed energy for the cushioning action can be secured, so that the cushioning properties can be further improved.

Next, as shown in FIG. 5, when the cushion collar 20 moves in the direction of arrow B, the cushion packing 50 according to the present embodiment moves in the groove 12 in the axial direction due to the pressure difference. Although it comes into pressure contact with the inner wall of the concave groove 12 on the cushion chamber 16 side, fluid flows from the counter-cushion chamber into the cushion chamber 16 through the outer circumferential surface channel groove 59 and the end surface channel groove 57 as shown by the arrows in FIG. Because it is distributed,
The pressure inside the cushion chamber 16 will not drop more than necessary and will not interfere with the smooth return movement of the piston 14 (FIG. 6) in the direction of arrow B.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention.

[0024]

[Effects of the Invention] As described above, according to the cushion packing according to the present invention, the inward protrusion is formed between the center part of the inner peripheral surface of the packing body and the end part on the side of the cushion chamber. When the sliding member enters the inside of the packing body, the packing body is rotated so that the inner circumferential side of the packing body approaches the cushion chamber side and the outer circumferential side of the packing body approaches the side opposite to the cushion chamber. A lip-shaped seal portion formed at the end on the cushion chamber side is pressed against the inner surface of the groove and sealed. Therefore, good sealing performance is maintained, and the end surface of the packing body on the opposite side of the cushion chamber does not come into contact with the edge of the groove, which prevents damage to the packing and increases durability. performance is improved compared to before.

Furthermore, since the sealing is performed by a lip-shaped sealing portion that is easily deformed, good sealing performance can be maintained even if the packing body is slightly deformed when the packing is attached. Therefore, since the ring having an L-shaped cross section is not required, the work of attaching this ring is no longer necessary, and the workability of attaching the packing can be improved, and costs can also be reduced.

Furthermore, since the inward protrusion is provided closer to the cushion chamber side, the volume of the cushion chamber can be increased compared to the conventional one, and a large amount of absorbed energy for cushioning action can be secured, resulting in improved cushioning properties. This can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cushion packing according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view when the large diameter portion of the cushion collar enters the cushion packing shown in FIG. 1;

FIG. 3 is a cross-sectional view when the cushion collar is not inserted into the cushion packing shown in FIG. 1;

FIG. 4 is a view taken from arrow IV in FIG. 3;

FIG. 5 is a cross-sectional view when the cushion collar is retracted from the cushion packing shown in FIG. 1;

FIG. 6 is a schematic cross-sectional view of a typical pressure cylinder.

FIG. 7 is a sectional view of a conventional cushion packing.

FIG. 8 is a sectional view of the conventional cushion packing shown in FIG. 7 in a deformed state.

[Explanation of symbols]

12 Groove 20 Cushion collar (sliding member) 50
Cushion packing 50a Packing body 51 Inner protrusion 54 Lip-shaped seal portion 57 End face channel groove

Claims (2)

[Claims] Claim 1: A sliding member is mounted so as to be movable in the axial direction in a concave groove extending in the circumferential direction formed in the pressure cylinder, and is slidable as appropriate on the surface of the sliding contact member that relatively reciprocates in the axial direction according to the reciprocating movement. In the pressure cylinder cushion packing, which performs a cushioning action by sealing a cushion chamber formed by being surrounded by a pressure cylinder member including the sliding contact member in response to reciprocating axial movement of the sliding contact member, the recess A packing body having a substantially rectangular cross section extending in the circumferential direction within the groove, and an inward protrusion formed on the inner circumferential surface of the packing body between the center portion of the inner circumferential surface and the end portion on the side of the cushion chamber. Department and
The outer peripheral surface of the packing body includes a lip-shaped seal formed at the end of the outer peripheral surface opposite to the cushion chamber, and a cushion chamber formed on the end surface of the packing body on the cushion chamber side so as to guide fluid in a radial direction. A cushion packing for a pressure cylinder consisting of an end flow channel groove formed on the side end surface. 2. The distance (m) between the top of the inward protrusion and the cushion chamber side end surface of the packing body is set to m≦0.5h with respect to the height (h) of the packing body. The cushion packing for a pressure cylinder according to claim 1.