JP2005220931A - Oil seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress increase of sliding load by maintaining sufficient lubricity of a sliding part of a lip seal 10 even under a high pressure condition. <P>SOLUTION: Since a plurality of circumference groove 13 formed on an inner circumference surface 12 on the outside of a seal edge part 11 of a seal lip 10 and relative projections 13 thereof form continuous wave surface shape, a crack having a starting point on the circumference groove 13 is not easily created even under a condition where high pressure acts on the seal lip 10. Consequently, groove depth "d" can be deepened not to be fully crushed under the high pressure condition. As a result, a lubricating condition of a sliding part of the seal lip 10 and a reciprocating rod 2 on the circumference groove 13 can be maintained even under high pressure condition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oil seal used as a sealing means for a reciprocating rod of a high-pressure gas cylinder, such as a rear hatch gas stay in an automobile, or as a sealing means for a reciprocating rod of a hydraulic device or the like.

  There are two types of oil seals, one for rotating and one for reciprocating movement, by bringing a seal lip into close contact with a relatively moving counterpart material. FIG. 5 is a half cross-sectional view showing a conventional oil seal used as a sealing means for a reciprocating rod of a cylinder device, cut along a plane passing through an axis, and this oil seal has an inner circumference made of a rubber-like elastic material. The seal lip 101 on the side and the gasket 102 on the outer periphery are integrally vulcanized (vulcanized and bonded) along the inner peripheral end and the outer peripheral end of the disk-shaped metal ring 103. This oil seal is fixed in close contact with the inner surface of a cylinder (not shown) in the gasket 102 on the outer peripheral side, and the outer peripheral surface of a reciprocating rod (not shown) in which the inner peripheral seal lip 101 is inserted through the cylinder. And is slidably in close contact with each other to provide a sealing function.

Since this type of oil seal is mounted so that the seal lip 101 faces the sealed space S in the cylinder, the pressure of the seal lip 101 against the outer peripheral surface of the reciprocating rod increases as the pressure in the sealed space S increases. Acts to increase force. For this reason, for the purpose of preventing the sliding load of the seal lip 101 with respect to the reciprocating rod from becoming excessive, for example, as disclosed in Patent Document 1 below, the seal lip 101 has an outer side than the seal edge portion 101a. It is also known to maintain lubricity under high-pressure conditions by forming a plurality of circumferential grooves continuous in the circumferential direction on the inner peripheral surface 101b and causing these circumferential grooves to function as an oil reservoir for lubrication. It has been.
Japanese Utility Model Publication No. 7-23863

  However, conventionally, the circumferential groove for lubrication formed on the outer inner peripheral surface 101b of the seal lip 101 has been formed shallow so as not to cause cracks and the like, and therefore, for example, a gas stay in the rear hatch of an automobile, etc. As described above, under the usage conditions in which the inside of the cylinder is extremely high in pressure, the circumferential groove is almost crushed as the pressure of the seal lip 101 increases due to pressure, so the amount of oil retained in the circumferential groove is small. As a result, a sufficient liquid lubricating film is not formed on the sliding surface with the reciprocating rod, and lubrication is likely to be insufficient.

  Further, when the reciprocating rod is stopped, the oil in the circumferential groove tends to decrease. Therefore, particularly in the operation of the reciprocating rod after being stopped for a long time, the lubricating oil film runs out of the sliding surface of the seal lip 101 (squeeze). Out) may cause abnormal noise due to stick-slip phenomenon accompanying sliding and may cause early wear.

  The present invention has been made in view of the above points, and its technical problem is to maintain sufficient lubricity of the sliding portion of the seal lip with respect to the reciprocating rod even under high pressure conditions. An object of the present invention is to provide an oil seal capable of effectively suppressing an increase in load.

  As a means for effectively solving the technical problem described above, the oil seal according to the invention of claim 1 includes a plurality of circumferential grooves continuous in the circumferential direction on the inner peripheral surface outside the seal edge portion of the seal lip. The circumferential grooves and the relative protrusions between them form a continuous wavefront.

  Further, the oil seal according to the invention of claim 2 is formed with a plurality of circumferential grooves continuous in the circumferential direction on the inner circumferential surface outside the seal edge portion of the seal lip, and the groove on the seal edge portion side in each circumferential groove. The shoulder has an obtuse angle, and the groove shoulder opposite to the seal edge portion forms an acute angle.

  According to the oil seal of the first aspect of the present invention, the plurality of circumferential grooves formed for lubrication on the inner circumferential surface of the seal lip and the relative protrusions therebetween form a continuous wavefront shape. Even when a high pressure is applied to the lip, cracks starting from the circumferential groove are unlikely to occur, so that the groove depth can be deepened so as not to be completely crushed even under high pressure conditions. As a result, the lubrication condition of the sliding surface of the seal lip due to the circumferential groove is maintained even under high pressure conditions, and it is difficult for the lubricating oil film to break after a long period of stoppage. Can be effectively prevented.

  According to the oil seal according to the invention of claim 2, of the groove shoulders on both sides of the plurality of circumferential grooves formed for lubrication on the inner peripheral surface of the seal lip, the groove shoulder on the seal edge side forms an obtuse angle. Since the groove shoulder on the opposite side to the seal edge makes an acute angle, each groove shoulder on the opposite side to the seal edge functions as a small seal lip facing the sealed space, so that oil is retained in the circumferential groove. The lubrication state of the sliding surface of the seal lip due to the circumferential groove is maintained even under high pressure conditions, and it is difficult for the lubricating oil film to break after a long period of stoppage. Early wear can be effectively prevented.

  FIG. 1 is a half sectional view showing a first preferred embodiment of the oil seal according to the present invention by cutting along a plane passing through its axial center, and FIG. 2 is a partial sectional view showing the attached state.

  An oil seal 1 shown in FIG. 1 is made of a rubber-like elastic material and is connected to an inner peripheral side seal lip 10 and an outer peripheral side gasket 20 which are continuous in the circumferential direction. It is integrally vulcanized and molded (vulcanized and bonded) along the outer peripheral end 32. As the rubber-like elastic material, it is preferable to use a material having excellent wear resistance, such as urethane rubber, fluorine rubber, and acrylic rubber.

  The oil seal 1 is configured by positioning and setting a metal ring 30 pre-applied with a vulcanizing adhesive in a predetermined mold (not shown), and between the metal ring 30 and the inner surface of the mold when the mold is closed. The formed annular cavity was filled with an unvulcanized rubber material for molding and heated and pressurized, so that the vulcanization adhesion to the metal ring 30 was made simultaneously with the vulcanization molding of the seal lip 10 and the gasket 20. Is.

  The seal lip 10 protrudes from the inner periphery of the metal ring 30 toward one side in the axial direction, and extends in a taper shape so that the diameter gradually decreases from the base 10a toward the tip 10b. A seal edge portion 11 is formed on the inner peripheral side of the tip 10b of the seal lip 10, and a plurality of continuous inner circumferential surfaces 12 are provided on the inner peripheral surface 12 on the outer side in the axial direction (the metal ring 3 side). A circumferential groove 13 is formed. As shown in FIG. 2, the groove bottom and the shoulder of each circumferential groove 13 are formed in an R shape. Therefore, each circumferential groove 13 and the relative protrusion 14 between the circumferential grooves 13 are continuous wavefront shapes. I am doing.

  The oil seal 1 according to the above-described embodiment is installed in the cylinder so that the seal lip 10 faces the sealed space S in a cylinder (not shown) such as a gas stay. By being press-fitted into the inner surface, the inner seal lip 10 is fixed in close contact with the outer peripheral surface of the reciprocating rod 2 inserted into the cylinder so as to be slidable with an appropriate margin. Thus, the sealing function for the gas to be sealed in the sealed space S is performed. Further, since the seal lip 10 has a taper shape that gradually decreases in diameter from the base portion 10a toward the tip end 10b, the tightening margin with respect to the reciprocating rod 2 is the largest at the seal edge portion 11. This provides excellent sealing performance.

  Further, in order to prevent the seal lip 10 from being dragged and expanded due to friction with the reciprocating rod 2 in the process in which the reciprocating rod 2 is operated in the vertical direction in FIGS. The radial wall thickness is relatively large and the axial protruding length is relatively short. In the illustrated example, the radial wall thickness and the axial protruding length are approximately the same.

  A plurality of peripheral grooves 13 formed on the inner peripheral surface 12 outside the seal edge portion 11 of the seal lip 10 functions as an oil reservoir that holds lubricating oil and promotes formation of a lubricating oil film, and is reciprocated. The increase of the contact area with the moving rod 2 is suppressed.

  And according to this form, since the some peripheral groove 13 in the internal peripheral surface 12 of the seal lip 10 and the relative protrusion 14 between them make the wave surface shape which continued mutually, it acts on the outer peripheral surface of the seal lip 10. Even if the gas pressure in the sealed space S becomes extremely high, cracks starting from the circumferential groove 13 are unlikely to occur, so that the groove depth can be deepened so as not to be completely crushed even under high pressure conditions. Specifically, the size of the circumferential groove 13 is such that the groove depth d is 0.02 to 0.7 mm and the groove interval p is 0.15 to 2 mm to ensure the rigidity of the protrusions 14, thereby sealing the circumferential groove 13 even under high pressure conditions. The sliding state 12 of the lip 10 is maintained in a lubricated state, and it is difficult for the lubricant film to run out (squeeze out) after stopping for a long time, effectively preventing abnormal noise due to insufficient lubrication during sliding and premature wear. can do.

  In addition, since the circumferential groove 13 and the relative protrusion 14 between them form a continuous wave front, the lubricating oil film formed on the outer circumferential surface of the reciprocating rod 2 is less likely to be scraped to the atmosphere side. This also functions effectively to maintain lubricity.

  Next, FIG. 3 is a half sectional view of the oil seal according to the present invention, which is shown in a non-mounted state, cut by a plane passing through its axis, and FIG. 4 is a partial sectional view of the mounted state. is there.

  In the oil seal 1 shown in FIG. 3, a plurality of circumferential grooves 13 that are continuous in the circumferential direction are formed on the inner peripheral surface 12 that is axially outside (the metal ring 3 side) from the seal edge portion 11 of the seal lip 10. Has been. As shown in FIG. 4, the groove bottom of each circumferential groove 13 is formed in an R shape, the groove shoulder 13a on the seal edge portion 11 side forms an obtuse angle, and the groove shoulder 13b on the opposite side to the seal edge portion 11 Has an acute angle.

  The other parts basically have the same configuration as that shown in FIG. 1, that is, the oil seal 1 is such that the seal lip 10 faces the sealed space S in a cylinder (not shown) such as a gas stay. The reciprocating rod 2 is mounted in the cylinder and fixed in close contact by being press-fitted into the inner surface of the cylinder by the gasket 20 on the outer peripheral side, and the seal lip 10 on the inner peripheral side is inserted into the cylinder. A sealing function is achieved by being slidably brought into close contact with the outer peripheral surface of the material at an appropriate fastening allowance.

  A plurality of peripheral grooves 13 formed on the inner peripheral surface 12 outside the seal edge portion 11 of the seal lip 10 functions as an oil reservoir that holds lubricating oil and promotes formation of a lubricating oil film, and is reciprocated. The increase of the contact area with the moving rod 2 is suppressed. And since the groove shoulder 13a by the side of the seal edge part 11 in each circumferential groove 13 makes an obtuse angle, and the groove shoulder 13b of the other side makes an acute angle, each groove shoulder 13b which makes an acute angle faces the sealed space S side, respectively. Thus, it functions as a small sealing lip having a self-sealing function by the pressure in the circumferential groove 13. Therefore, even if the gas pressure in the sealed space S becomes extremely high, oil is easily held in the circumferential groove 13 and the sealing performance with respect to the sealed space S is improved.

  Further, since the groove bottom of the circumferential groove 13 has an R shape, even if the gas pressure in the sealed space S acting on the outer peripheral surface of the seal lip 10 becomes extremely high, cracks starting from the circumferential groove 13 are unlikely to occur. For this reason, the groove depth can be increased so as not to be completely crushed even under high pressure conditions. Specifically, as in the first embodiment described above, the size of the circumferential groove 13 is such that the groove depth is 0.02 to 0.7 mm and the groove interval is 0.15 to 2 mm, so that the circumferential groove 13 can be used even under high pressure conditions. The lubrication state of the sliding surface 12 of the seal lip 10 is maintained, and it is difficult for the lubricating oil film to be cut off after a long period of stoppage. This effectively prevents abnormal noise due to insufficient lubrication during sliding and early wear. Can do.

  Further, since the groove shoulder 13a on the seal edge portion 11 side in each circumferential groove 13, in other words, the groove shoulder 13a facing the atmosphere side forms an obtuse angle, the lubricating oil film formed on the outer peripheral surface of the reciprocating rod 2 is in the atmosphere. This is effective for maintaining lubricity.

FIG. 3 is a half sectional view of an unmounted state showing a preferred first embodiment of the oil seal according to the present invention by cutting along a plane passing through its axis. It is a fragmentary sectional view of the mounting state in the oil seal of FIG. FIG. 5 is a half cross-sectional view of a non-mounted state in which a second preferred embodiment of the oil seal according to the present invention is cut along a plane passing through its axis. It is a fragmentary sectional view of the mounting state in the oil seal of FIG. FIG. 5 is a half sectional view showing a conventional oil seal used as a sealing means for a reciprocating rod, cut along a plane passing through an axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil seal 2 Reciprocating rod 10 Seal lip 10a Base part 10b Tip 11 Seal edge part 12 Inner peripheral surface 13 Circumferential groove 13a, 13b Groove shoulder 14 Relative protrusion 20 Gasket 30 Metal ring S Sealing space

Claims (2)

  A plurality of circumferential grooves (13) continuous in the circumferential direction are formed on the inner peripheral surface (12) outside the seal edge portion (11) of the seal lip (1). An oil seal characterized in that the ridges (14) have a continuous wavefront shape.   A plurality of circumferential grooves (13) continuous in the circumferential direction are formed on the inner peripheral surface (12) outside the seal edge portion (11) in the seal lip (1), and the seal edge portions ( 11) An oil seal characterized in that the groove shoulder (13a) on the side forms an obtuse angle and the groove shoulder (13b) on the side opposite to the seal edge part (11) forms an acute angle.

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