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
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/16—Sealings between relatively-moving surfaces
  • F16J15/164—Sealings between relatively-moving surfaces the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid
• • 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
  • F16F9/368—Sealings in pistons
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49229—Prime mover or fluid pump making
  • Y10T29/49249—Piston making
  • Y10T29/49252—Multi-element piston making
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49229—Prime mover or fluid pump making
  • Y10T29/49249—Piston making
  • Y10T29/49256—Piston making with assembly or composite article making
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49229—Prime mover or fluid pump making
  • Y10T29/49249—Piston making
  • Y10T29/49256—Piston making with assembly or composite article making
  • Y10T29/49261—Piston making with assembly or composite article making by composite casting or molding

Definitions

• a shock absorber piston which has a piston body which is provided on its circumferential surface with a circumferential web which is adjoined by a plurality of axially extending webs on one side of the circumferential web.
• a seal made of thermoplastic material is injection-molded onto this piston body in the injection molding process, with the webs, which extend in the axial direction, with their intervening grooves completely filled with seal material, serving to reliably anchor the seal material.
• the seal applied in the injection molding enables a close tolerance in order to avoid the so-called "blow-by” and thus to reliably seal the cylinder spaces assigned to one another.
• the process for producing such injection molded seals is relatively complex.
• a piston-cylinder arrangement is known, the piston body of which has a plurality of circumferential grooves on its circumferential surface.
• a cup-shaped preform made of PTFE (polytetrafluoroethylene) is provided to apply the seal, which is first loosely placed on the piston body.
• the piston body prepared in this way is then first pressed into a highly heated form and calibration cylinder, the PTFE material being influenced by heat into the grooves on the circumferential surface of the
• Piston body is pressed.
• the piston body with the pressed-on seal is then cooled in an appropriately designed cooling cylinder.
• the grooves are completely filled with the sealing material, so as to bring about a form-fitting, firm connection of the seal to the peripheral surface of the piston body.
• the front surface For use as a shock absorber piston, the front surface must then be used of the piston body on one side covering bottom surface of the preform are removed.
• a shock absorber piston which differs in its manufacture from the method described above essentially only in that instead of a cup-shaped preform a stamped circular disk is used to apply the seal.
• This circular disc is placed on one end of the piston body.
• the piston body prepared in this way is in turn pressed into a heated forme and calibration cylinder, the annular disc being folded as a band onto the peripheral surface of the piston body and then pressed into the grooves running in the peripheral direction of the piston body under the influence of heat.
• the piston provided with its pressed-on seal is then passed through a cooling pipe.
• the sealing material also fills the grooves practically completely, so that the seal is positively and firmly connected to the peripheral surface of the piston body.
• the invention has for its object to provide a piston, in particular shock absorber piston, in which the disadvantages described above are avoided.
• a piston for a piston-cylinder arrangement in particular shock absorber piston
• a piston body which is provided on its circumferential surface with at least one circumferential web
• a collar-shaped seal is also provided on the circumferential surface of the piston body from a hot deformable Plastic material is molded on so that the web is molded into the material of the seal only over part of its height.
• At least one circumferential web is sufficient, onto which the sleeve-shaped seal is molded in the manner described in EP-A-682 190. Surprisingly, it has also been found that it is sufficient if the web is molded into the material of the seal only over part of its height. On the one hand, this results in a perfect positive fit between the sleeve-shaped seal and the piston body and, on the other hand, only a moderate deformation of the plastic material, so that not only less pressing forces have to be exerted, but also a material flow during the forming takes place to a much lesser extent and thus a adverse influence on the material structure is practically avoided.
• the web is then expediently arranged in the vicinity of an end face of the piston body, preferably the end face which is subjected to greater loads.
• At least two circumferential webs are arranged on the peripheral surface which delimit a groove. This results in a reliable positive connection even at higher working pressures.
• the arrangement of one, but also of two circumferential webs can be machined cost-effectively.
• the cuff-shaped seal with its edges projects beyond the associated end faces of the piston body. Since the cuff-shaped seal is produced from an annular disk according to the known method, the phenomenon of "recall" of the plastic material described in EP-A-0 682 190 can be used to the effect that the inner diameter of the annular disk is limited Edge after application to the piston body contracts inwards and the edge of the sleeve-shaped seal originating from the outer edge of the annular disc resets itself towards the outside and projects beyond the remaining peripheral surface of the sleeve-shaped seal in the manner of a sealing lip. If the piston body is installed in such a way that the piston surface with the lip facing outwards faces the pressure side, i.e.
• At least one web is arranged in an area adjacent to an end face of the piston body.
• only two webs are then expediently provided, which then only delimit a groove in the region of the circumferential surface of the piston body lying in between.
• the webs can be of relatively wide dimensions, the groove laterally delimited by the webs then being two to three times as wide as a web width te. This considerably simplifies the shape of the contour of the peripheral surface of the piston body.
• the piston body is assembled from at least two sub-elements and has a division plane running perpendicular to the piston axis.
• a structure of a piston body is particularly useful for the production of the piston body in the powder metallurgical process, i. H. suitable as a sintered metal body.
• the shape of the two sub-elements is particularly favorable when each sub-element has only one circumferential web, so that the sub-elements joined in mirror image delimit a corresponding groove with their webs. This also enables the cost-effective production of an undercut groove, since there is no machining.
• Fig. 1 shows a partial section in the axial direction through a piston-cylinder arrangement for one
• Fig. 2 shows an enlarged partial section through the
• Fig. 3 is an enlarged partial section through a piston with a web.
• Fig. 1 shows an axial section through a shock absorber, which connects two parts movable relative to each other, for example a vehicle axle and a vehicle frame.
• the shock absorber has a cylinder part 1 which is connected to one of the two parts which can be moved relative to one another.
• a piston 2 is guided in the cylinder 1 and is fastened to a piston rod 3, the free end of which is attached to the other part of the two parts which are movable relative to one another le is set.
• the cylinder 1 is closed on both sides and filled with a hydraulic fluid, so that the piston-cylinder arrangement is designed to be double-acting, the piston separating two cylinder spaces 4, 5 from one another.
• the piston body 6 of the piston 2 has a plurality of passage channels 7, 8 running next to one another.
• the passage channels 7, 8 are each covered on their outlet side to be explained in terms of their function with a throttle valve 7.1 or 8.1.
• the arrangement is such that, for example, three passage channels 7 and three passage channels 8 are arranged alternately around the cylinder axis in a star shape.
• the circumferential surface of the piston 2 is provided with a sleeve-shaped seal 9, which ensures that the cylinder space 4 is sealed off from the cylinder space 5.
• a sleeve-shaped seal 9 ensures that the cylinder space 4 is sealed off from the cylinder space 5.
• a piston 2 is shown in an enlarged view without the arrangement of the throttle valves 7.1 and 8.1 in partial section.
• the piston body 6 is provided on its circumferential surface with two webs 10, which in the exemplary embodiment shown here are arranged such that they also each contain a part of the end face 4.1 or 5.1 of the piston body 6.
• the two webs 10 delimit a groove 11 on the circumferential surface of the piston body 6.
• the arrangement can also be made such that at least one of the webs 10 is set back somewhat from its associated end face 4.1 and / or 5.1.
• the sleeve-shaped seal 9 arranged on the circumferential surface of the piston body 6 consists of a thermally deformable plastic, preferably of PTFE.
• the cuff-shaped seal 9 has been molded onto the circumferential surface of the piston body 6 by hot forming from an annular disc, the edge 9.1 of the seal 9 being formed by the inner edge of the
• Annular disk is formed, while the edge 9.2 is formed by the outer edge of the annular disk.
• the circular washer was dimensioned in its ring width so that it was wider than the thickness of the piston body 6 in the axial extent, so that after reshaping the from the inner edge of the
• the edge 9.1 coming from the annular disc is drawn inwards, while the edge 9.2 originating from the outer edge of the annular disc is bent outward and forms a sealing lip in function.
• the webs 10 are molded into the material of the sleeve-shaped seal 9 only over part of their height, so that a certain amount of free space remains between the material of the seal 9 and the bottom of the groove 11, so that during molding the seal 9, the sealing material can flow freely and without constraint into the groove 11.
• the cylindrical outer surface 12 of the seal 9 is calibrated at the same time, so that the desired tolerances on the inner diameter of the cylinder 1 can be maintained.
• the piston body 6 is made from two sub-elements 6.1 and 6.2.
• FIG. 3 shows an embodiment modified compared to FIG. 2.
• the same reference numerals relate to the same elements, so that reference can be made to the description of FIG. 2.
• FIG. 3 The embodiment shown in FIG. 3 is intended for applications with a lower tensile pressure load, so that the piston body 6 is provided with only one circumferential web 10.
• the end face 4.1 of the piston body 6 is subjected to the higher pressure, so that the web 10 is arranged here near this end face.
• the cuff-shaped seal 9 is molded onto the piston body 6 in the manner described above, with the circumferential ridge 10 again being molded into the material of the cuff-shaped seal 9 only over part of its height.
• the configuration according to the invention can also be machined with just one or two webs delimiting a groove with reasonable effort.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Fluid-Damping Devices (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)
• Sealing Devices (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=7884434

Family Applications (1)

Country Status (9)

Families Citing this family (12)

Citations (6)

Family Cites Families (4)

• 1998
  • 1998-10-14 DE DE19847341A patent/DE19847341A1/de not_active Withdrawn
• 1999
  • 1999-10-12 ES ES99953780T patent/ES2190261T3/es not_active Expired - Lifetime
  • 1999-10-12 EP EP99953780A patent/EP1121544B1/de not_active Expired - Lifetime
  • 1999-10-12 WO PCT/EP1999/007642 patent/WO2000022319A1/de not_active Ceased
  • 1999-10-12 AU AU10352/00A patent/AU1035200A/en not_active Abandoned
  • 1999-10-12 JP JP2000576190A patent/JP2002527692A/ja not_active Withdrawn
  • 1999-10-12 AT AT99953780T patent/ATE231953T1/de not_active IP Right Cessation
  • 1999-10-12 DE DE59904189T patent/DE59904189D1/de not_active Expired - Lifetime
  • 1999-10-12 BR BR9914434-4A patent/BR9914434A/pt not_active IP Right Cessation
• 2001
  • 2001-04-13 US US09/834,322 patent/US20020046651A1/en not_active Abandoned
• 2004
  • 2004-11-15 US US10/988,954 patent/US7178237B2/en not_active Expired - Fee Related

Patent Citations (6)

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