JP4699594B2 - Fluid pressure packing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an annular packing having a U-shaped cross section that is interposed in a mounting groove so as to be in sliding contact with a sliding member and seals fluid pressure such as pneumatic pressure and hydraulic pressure.
[0002]
[Prior art]
Conventionally, as a fluid pressure packing used for a hydraulic cylinder or the like, for example, there are those shown in FIGS.
[0003]
This will be described. The ring-shaped packing 10 having a U-shaped cross section seals between the cylinder 20 and the piston rod (sliding member) 30 and is accommodated in a mounting groove 21 formed in the cylinder 20.
[0004]
The packing 10 includes a sliding side lip 1 facing the piston rod 30, a heel portion 2 facing the opening end side of the mounting groove 21, a shoulder portion 3 facing the corner of the mounting groove 21, and the mounting groove 21. It has a fixed side lip 4 that faces the bottom surface, and a U groove portion 5 that is recessed in an annular shape between both lips 1 and 4 and receives hydraulic pressure.
[0005]
In the packing 10, as shown by an arrow in FIG. 5, the sliding side lip 1 is pressed against the piston rod 30 by the hydraulic pressure received by the U groove portion 5, and the fixed side lip 4 is pressed against the bottom surface 25 of the mounting groove 21. And the piston rod 30 are sealed.
[0006]
[Problems to be solved by the invention]
However, in such a conventional fluid pressure packing 10, when the U groove portion 5 is subjected to a high pressure, the heel portion 2 protrudes into the annular gap 29 formed between the cylinder 20 and the piston rod 30, and the friction increases. There was a possibility.
[0007]
FIG. 5 shows the result of analyzing the stress distribution of the packing 10, and high stress is locally generated at the heel portion 2. As a result, the contact surface pressure of the heel portion 2 with respect to the piston rod 30 becomes excessive, and the balance with the contact surface pressure gradient of the sliding side lip 1 is lost. For this reason, the scraping property of the liquid film by the heel portion 2 is increased, and there is a possibility that the sealing liquid leaks due to the scraping of the liquid film. Moreover, if the scraping property of the liquid film by the heel portion 2 is large, the lubricity of the sliding portion is deteriorated and there is a possibility that the wear is accelerated.
[0008]
The present invention has been made in view of the above problems, and an object of the present invention is to optimize the surface pressure distribution on the sliding member in the fluid pressure packing.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an annular seal groove portion that is received in a fluid pressure , accommodated in an annular mounting groove formed in the cylinder, an annular sliding side lip that is pressed against the sliding member by the fluid pressure, and a mounting groove an annular heel facing the opening end side, possess a shoulder portion of the annular facing the corner portion of the mounting groove, and an annular stationary side lip which is pressed against the bottom surface of the mounting groove by a fluid pressure, a sliding member Applies to packing that seals between .
[0010]
It has an annular first inclined surface that inclines so as to gradually move away from the sliding member from the tip of the sliding lip to the heel portion in a free state where fluid pressure does not act on the seal groove, and the heel portion continues from the first inclined surface. And curved so as to have an arc-shaped cross section having a larger radius of curvature than the seal groove, and gradually approaches the end face of the mounting groove perpendicular to the central axis of the cylinder from the heel portion to the shoulder portion in a free state where fluid pressure does not act. And an annular third inclined surface that is inclined so as to gradually approach the bottom surface of the mounting groove toward the tip of the fixed side lip.
[0012]
According to a second invention, in the first invention, an annular flat portion extending substantially parallel to the bottom surface of the mounting groove from the shoulder portion to the fixed side lip in a free state in which no fluid pressure acts on the seal groove portion, and the flat portion to the fixed side An annular third inclined surface that inclines so as to gradually approach the bottom surface of the mounting groove toward the tip of the lip is provided.
[0013]
According to a third aspect , in the first aspect, an annular third inclined surface that is inclined so as to gradually approach the bottom surface of the mounting groove from the shoulder portion to the distal end of the fixed side lip in a free state in which fluid pressure does not act on the seal groove portion. It was characterized by having.
[0014]
According to a fourth invention, in any one of the first to third inventions, the depth of the seal groove is set to 1/2 or more with respect to the total height of the packing.
[0015]
Operation and effect of the invention
According to the first invention, as the fluid pressure rises, even if the packing is deformed so that the first inclined surface is pressed against the sliding member from the tip of the sliding lip, the heel portion becomes the sliding member. Since it does not approach too much, it can prevent that a heel part protrudes between a cylinder and a sliding member, and it can avoid that packing is damaged or friction becomes large.
[0016]
The stress generated in the packing is suppressed to a low value in a wide range from the heel portion to the seal groove portion, and the surface pressure distribution on the sliding member of the packing is optimized. For this reason, the scraping of the liquid film by the heel portion is suppressed, the leakage of the working fluid is suppressed, the lubricity of the sliding portion is maintained, and the wear of the packing can be suppressed.
[0017]
As the fluid pressure increases, the packing is deformed so that the second inclined surface is pressed against the end surface of the mounting groove, and the heel portion is separated from the sliding member, so that the heel portion is between the cylinder and the sliding member. It can be prevented from sticking out.
[0018]
The stress generated in the packing is suppressed to a low value in a wide range from the heel portion to the seal groove portion, and the surface pressure distribution on the sliding member of the packing is optimized.
[0019]
According to the second invention, as the fluid pressure increases, the packing is deformed so that the flat portion and the third inclined surface are pressed against the bottom surface of the mounting groove, and the heel portion is separated from the sliding member. Can be prevented from protruding between the cylinder and the sliding member.
[0020]
The stress generated in the packing is suppressed to a low value in a wide range from the heel portion to the seal groove portion, and the surface pressure distribution on the sliding member of the packing is optimized.
[0021]
According to the third invention, as the fluid pressure rises, the packing is deformed so that the third inclined surface is pressed against the bottom surface of the mounting groove, and the heel portion is separated from the sliding member. It is possible to prevent protrusion between the sliding members.
[0022]
The stress generated in the packing is suppressed to a low value in a wide range from the heel portion to the seal groove portion, and the surface pressure distribution on the sliding member of the packing is optimized.
[0023]
According to the fourth aspect of the invention, the length of the sliding lip is sufficiently secured, and even if the heel portion is deformed away from the sliding member as the fluid pressure increases, the sliding lip becomes the piston rod. Follows and can secure sealing performance.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0025]
As shown in FIG. 2, the ring-shaped packing 10 having a U-shaped cross section seals between the cylinder 20 and the piston rod (sliding member) 30, and is accommodated in an annular mounting groove 21 formed in the cylinder 20. Be dressed.
[0026]
As shown in FIG. 1, the packing 10 includes a U groove portion (seal groove portion) 5 that is recessed in an annular shape and receives hydraulic pressure, an annular sliding lip 1 that is pressed against the piston rod 30 by hydraulic pressure, and an end face 23 of the mounting groove 21. And the annular heel portion 2 facing the corner portion formed between the piston rod 30 and the annular shoulder portion 3 facing the corner portion formed between the end surface 23 and the bottom surface 25 of the mounting groove 21 and attached by hydraulic pressure. And an annular fixed side lip 4 pressed against the bottom surface 25 of the groove 21.
[0027]
The packing 10 includes an annular first inclined surface 11 that inclines so as to gradually move away from the piston rod 30 from the sliding side lip 1 to the heel portion 2 and a shoulder from the heel portion 2 in a free state where no hydraulic pressure acts on the U groove portion 5. An annular second inclined surface 12 that inclines so as to gradually approach the end surface 23 of the attachment groove 21 over the portion 3, and an annular flat portion 14 that extends substantially parallel to the bottom surface 25 of the attachment groove 21 from the shoulder portion 3 to the fixed side lip 4. And an annular third inclined surface 13 that inclines so as to gradually approach the bottom surface 25 of the mounting groove 21 from the flat portion 14 to the fixed side lip 4.
[0028]
The tip of the sliding lip 1 has an edge to improve the oil film scraping property. However, the present invention is not limited thereto, and the tip of the sliding lip 1 may be formed in an arc shape.
[0029]
In FIG. 1, the cross section of the first inclined surface 11 extends linearly and has an angle θ <b> 1 with respect to the central axis of the cylinder 20. The cross section of the U groove 5 is also inclined at substantially the same angle θ1, and the sliding lip 1 extends with a substantially constant thickness.
[0030]
The cross section of the heel portion 2 is curved in an arc shape, and is continuous with the first inclined surface 11 and the second inclined surface 12 without a step. The radius of curvature of the heel portion 2 is arbitrarily set within a range larger than the radius of curvature of the U-groove portion 5.
[0031]
In FIG. 1, the cross section of the second inclined surface 12 extends linearly and has an angle θ <b> 2 with respect to the end surface 23 of the mounting groove 21 orthogonal to the central axis of the cylinder 20.
[0032]
The cross section of the shoulder portion 3 is curved in an arc shape with a small curvature radius, and the second inclined surface 12 and the flat portion 14 are continuous without a step.
[0033]
In FIG. 1, the cross section of the third inclined surface 13 extends linearly and has an angle θ3 with respect to the bottom surface 25 of the mounting groove 21 parallel to the central axis of the cylinder 20. The cross section of the U groove 5 is also inclined at substantially the same angle θ3, and the fixed side lip 4 extends with a substantially constant thickness.
[0034]
The depth D of the U groove portion 5 is set to H / 2 or more with respect to the total height H of the packing 10 to ensure the length of the sliding side lip 1 and the fixed side lip 4.
[0035]
Next, the operation of the embodiment of the present invention configured as described above will be described.
[0036]
The packing 10 accommodated in the mounting groove 21 of the cylinder 20 is pressed against the piston rod 30 by the hydraulic pressure acting on the U-groove portion 5 as shown by the arrow in FIG. Is pressed against the bottom surface 25 of the mounting groove 21 to seal between the cylinder 20 and the piston rod 30.
[0037]
As the hydraulic pressure acting on the U-groove 5 rises, the packing 10 deforms (1) , (2) , (3) . The deformations (1) and (2) occur almost simultaneously, and then the deformation (3) occurs.
(1) The second inclined surface 12 is deformed so as to be pressed against the end surface 23 of the mounting groove 21 from the shoulder portion 3.
(2) The third inclined surface 13 and the flat portion 14 are deformed so as to be pressed against the bottom surface 25 of the mounting groove 21 from the tip of the fixed side lip 4.
(3) The first inclined surface 11 is deformed so as to be pressed against the piston rod 30 from the tip of the sliding lip 1.
[0038]
As the hydraulic pressure rises, the packing 10 undergoes the deformations (1) and (2) , and the heel portion 2 is separated from the piston rod 30, so that an annular gap is created between the cylinder 20 and the piston rod 30. It is possible to prevent the gasket 10 from sticking out and damage the packing 10 or increase the friction.
[0039]
FIG. 2 shows the result of analysis of the stress distribution of the packing 10, but it is resolved that high stress is locally generated in the heel portion 2, and the stress generated in the packing 10 is spread over a wide range from the heel portion 2 to the U groove portion 5. The surface pressure distribution with respect to the piston rod 30 of the packing 10 is optimized by being suppressed to a low value. For this reason, the oil film scraping by the heel portion 2 is suppressed, the leakage of hydraulic oil is suppressed, the lubricity of the sliding portion is maintained, and the wear of the packing 10 is suppressed.
[0040]
Further, by setting the depth D of the U-groove portion 5 to H / 2 or more with respect to the total height H of the packing 10, the length of the sliding lip 1 is sufficiently secured, and the heel portion is increased as the hydraulic pressure increases. Even if 2 is deformed so as to be separated from the piston rod 30, the sliding side lip 1 follows the piston rod 30, and the sealing performance can be secured.
[0041]
As another embodiment, as shown in FIG. 3, the flat portion 14 in the above embodiment may be eliminated, and the third inclined surface 13 may be formed in the entire region from the shoulder portion 3 to the tip of the fixed lip 4. Good.
[0042]
In this case, as the hydraulic pressure acting on the U groove portion 5 increases, the packing 10 is deformed so that the third inclined surface 13 is pressed against the bottom surface of the mounting groove from the tip of the fixed lip 4, and is generated in the packing 10. The stress is suppressed to a low value in a wide range from the heel portion 2 to the U groove portion 5, and the surface pressure distribution of the packing 10 with respect to the piston rod is optimized.
[0043]
The present invention is not limited to the hydraulic cylinder, but can be applied to seal portions of other fluid pressure devices, and it is obvious that various modifications can be made within the scope of the technical idea.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a packing showing an embodiment of the present invention.
FIG. 2 is a stress distribution diagram of the packing.
FIG. 3 is a cross-sectional view of a packing showing another embodiment.
FIG. 4 is a sectional view of a packing showing a conventional example.
FIG. 5 is a stress distribution diagram of the packing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sliding side lip 2 Heel part 3 Shoulder part 4 Fixed side lip 5 U groove part 10 Packing 11 First inclined surface 12 Second inclined surface 13 Third inclined surface 14 Flat part 20 Cylinder 21 Mounting groove 23 End surface 25 of mounting groove Bottom of groove

Claims (4)

An annular seal groove that is received in the annular mounting groove formed in the cylinder and receives fluid pressure, an annular sliding lip that is pressed against the sliding member by the fluid pressure, and an opening end side of the mounting groove. An annular heel portion, an annular shoulder portion facing the corner portion side of the mounting groove, and an annular fixed side lip pressed against the bottom surface of the mounting groove by fluid pressure, and the sliding member In the fluid pressure packing that seals the gap, it has an annular first inclined surface that is inclined so as to gradually move away from the sliding member from the tip of the sliding side lip to the heel portion in a free state where fluid pressure does not act, continuously the heel portion from the first inclined surface is curved to have an arcuate cross section having a larger radius of curvature than the seal groove, the sucrose from the heel portion in a free state in which the fluid pressure does not act An annular second inclined surface that inclines so as to gradually approach the end surface of the mounting groove that is orthogonal to the central axis of the cylinder toward the bottom of the cylinder, and gradually approaches the bottom surface of the mounting groove toward the tip of the fixed side lip. A fluid pressure packing having an inclined third inclined surface inclined. An annular flat portion extending substantially parallel to the bottom surface of the mounting groove from the shoulder portion to the tip of the fixed side lip in a free state where fluid pressure does not act, and the mounting groove of the mounting groove from the flat portion to the tip of the fixed side lip The fluid pressure packing according to claim 1, further comprising an annular third inclined surface that is inclined so as to gradually approach the bottom surface. The annular third inclined surface that is inclined so as to gradually approach the bottom surface of the mounting groove from the shoulder portion to the distal end of the fixed side lip in a free state where fluid pressure does not act. The fluid pressure packing described. The fluid pressure packing according to any one of claims 1 to 3, wherein the depth of the seal groove is set to 1/2 or more of the total height of the packing.

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