Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/36—Special sealings, including sealings or guides for piston-rods
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
  • F15B1/02—Installations or systems with accumulators
  • F15B1/04—Accumulators
  • F15B1/08—Accumulators using a gas cushion; Gas charging devices; Indicators or floats therefor
  • F15B1/24—Accumulators using a gas cushion; Gas charging devices; Indicators or floats therefor with rigid separating means, e.g. pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/16—Sealings between relatively-moving surfaces
  • F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
  • F16J15/3244—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with hydrodynamic pumping action
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/56—Other sealings for reciprocating rods
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
  • F05C2225/00—Synthetic polymers, e.g. plastics; Rubber
  • F05C2225/04—PTFE [PolyTetraFluorEthylene]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2201/00—Accumulators
  • F15B2201/20—Accumulator cushioning means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2201/00—Accumulators
  • F15B2201/20—Accumulator cushioning means
  • F15B2201/205—Accumulator cushioning means using gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2201/00—Accumulators
  • F15B2201/30—Accumulator separating means
  • F15B2201/31—Accumulator separating means having rigid separating means, e.g. pistons
  • F15B2201/312—Sealings therefor, e.g. piston rings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2201/00—Accumulators
  • F15B2201/30—Accumulator separating means
  • F15B2201/315—Accumulator separating means having flexible separating means
  • F15B2201/3157—Sealings for the flexible separating means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2201/00—Accumulators
  • F15B2201/60—Assembling or methods for making accumulators
  • F15B2201/61—Assembling or methods for making separating means therefor
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S277/00—Seal for a joint or juncture
  • Y10S277/91—O-ring seal

Definitions

• This invention relates to a combination seal for sealing between closely opposing surfaces of two machine elements, one of which has an opean groove facing the other machine element, said groove having preferably a rectangular cross section, said seal comprising an expansion ring of an elastomeric material and designed to be positioned against the bottom of said groove, an intermediate sealing ring of a viscous-elastic synthetic material engaged by the expansion ring and shaped with a sealing surface for contact with the other machine element, and an outer ring of an elastomeric material and fitted into a separate groove on the sealing surface of the intermediate ring.
• Such seals are known from the DK published patent speci ication NQ. 146050 and are especially used as piston seals or rod seals between mating cylindrical surfaces of two mutually mobile machine elements, e.g. a hydrau ⁇ lic cylinder and its working piston or a solid end wall of a cylinder and a piston rod piercing it. They are effective to provide efficient sealing for fluids as well as gases within a wide pressure range, e.g. for pressure differences varying from 0 to 500 bar.
• the intermediate ring that is biassed by the elastomeric expansion ring may consist of polytetrafluoroeth lene or of some other highly temperature-resistant synthetic material with a high elasticity modulus and low friction, provides an efficient dynamic sealing at relatively big pres ⁇ sure differences, whereas the elastomeric outer ring at the sealing surface of the intermediate ring assures an effective sealing even at minor pressure differences between the two sides of the seal .
• the object of the invention is to widen the range of application of seals of the said type and provide an improvement of the known combination seal suitable in particular for gaseous fluids, e.g. to be applied in gas accumulators and heavily loaded shock absorbers.
• the invention solves this problem by means of a double acting combination seal, characterised in that the intermediate ring is designed with relative ⁇ ly sharp corners between the sealing surface and its end faces the parts of the sealing surface between each of said corners and said separate groove forming conical faces converging against the groove at a narrow slit angle.
• the narrow slit angle entails for both of the said conical faces that a fluid film which during a working stroke may flow as a leakage flow to the outer ring is returned to the high pressure side during the return stroke, essen ⁇ tially in the same manner as it is known per se from DK patent No.143667.
• the sealing ring is provided with with bevelled conical annular faces at said corners, resulting in an improved safety against undesired dislocations of material during installation of the seal. This is to say, that twisting and/or extrusion of the outer ring is substantially avoided, as it is known per se from Danish patent application No. 5806/83.
• the slit angle at parts of the sealing surface of the intermediate ring forming conical faces is preferably to be narrow, as this provides better hydrodynamic return forces. Practical experiments have proved that a slit angle of 1 to 5 is suitable.
• fig.1 illustrates the construction and opera ⁇ tion of a known combination seal
• fig.2 is an axial section at view of part of an embodiment of a combination seal accor ⁇ ding to the invention applied as piston seal
• - and fig. illustrates the mode of operation of the seal in fig.2.
• the intermediate ri ⁇ ig b which preferably is made of polytetrafluoroethylene , is biassed by the elastomeric expansion ring a with pressure forces which in the intermediate ring b may cause a distribution of stress as shown by the dotted curves s, whereby the distribution of the contact pressure over the sealing surface of the intermediate ring b on each side of the outer ring c will be mainly as shown by the pressure distribution curves P, i.e. with a maximum contact pressure on the central part of the sealing surface at the edges of the separate groove wherein the outer ring c is fitted.
• This pressure distribution prevents the return of a liquid film which during a working stroke is carried to the outer ring c, to the high pressure side during the return stroke, and as a result a fluid pressure may be built up around the outer ring c entailing in ury to the outer ring and con ⁇ sequently rendering the sealing deficient, especially at high working speeds.
• 1 designates the wall of a working cylinder, e.g. in a gas accumulator or a highly loaded shock absorber
• 2 in ⁇ dicates a piston that is mobile with a clearance relative to the cylindrical inner side of the wall 1.
• a groove 3 is provided to receive the seal according to the inven ⁇ tion.
• the combination seal comprises two juxtaposed expansion rings 4 and 5 of an elastomeric material, e.g. rubber or polyurethan, positioned against the bottom of the groove 3, an intermediate ring 6 of a viscous-elastic, deformable synthetic material e.g. PTFE virgin or modified with fillers known per se, this intermediate ring being biassed by the expansion rings 4 and 5, as well as an outer ring 8 positioned in a separate groove 7 in the intermediate ring 6 at the sealing surface 6b facing the machine element 2.
• the outer ring 8 may consist of the same elastomeric material as the expansion rings 4 and 5.
• the expansion rings 4 and 5 which individually engage grooves 9 and 10 on the bearing surface 6a of the intermediate ring 6, can be produced as 0- rings with an oval cross section, whereas the ela ⁇ stomeric outer ring 8 preferably has a mainly rectangular cross section with projecting corners causing a secure positioning and retention of the outer ring 8 in the groove 7.
• the intermediate ring 6 is provided at the ends of the sealing surface 6a with relatively sharp corners 16 and 17, at which in the illustrated, preferred embodiment bevelled
• conical faces 11 and 12 have been formed. Further ⁇ more the parts of the sealing surface 6b between each of the annular planes 11 and 12 and the separate groove 7 form conical faces 14 and 15 which converge towards the groove 7 leaving a narrow slit angle v in relation to the mating surface of the machine element 2.
• the expansion rings 4 and 5 act upon the intermediate ring 6 with forces K acting at a distance A on each side of the groove 7, as shown on fig.3.
• the parts of the intermediate ring 6 placed on each side of the groove 7, are hereby influenced by the moments k A with axes at the corners between the bottom of the groove 7 and the side walls.
• a di ⁇ stribution of the contact pressure is obtained along the sealing surface 6a as shown by the curves P' with maxima at the relatively sharp-edged corners 16 and 17 between the annular surfaces 11 , 12, and the conical surfaces 14, 15.
• the above described specific embodiment does not limit neither the design nor the applications of the combination seal according to the invention.
• the combination seal is suited for the same range of applications as the known seal according to the above mentioned DK patent No. 146050 and entails in particular a considerably improved seal with a reduced leakage rate at high working speeds between two machine elements.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Sealing Devices (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

Family

ID=26065746

Family Applications (1)

Country Status (5)

Cited By (4)

Families Citing this family (16)

Citations (7)

Family Cites Families (12)

• 1987
  • 1987-03-20 DK DK143887A patent/DK157947C/da not_active IP Right Cessation
• 1988
  • 1988-07-07 US US07/623,816 patent/US5156410A/en not_active Expired - Fee Related
  • 1988-07-07 WO PCT/DK1988/000113 patent/WO1990000693A1/en active IP Right Grant
  • 1988-07-07 EP EP88907262A patent/EP0424372B1/en not_active Expired - Lifetime
  • 1988-07-07 JP JP63505349A patent/JPH05505012A/ja active Pending

Patent Citations (7)

Non-Patent Citations (1)

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