EP0135386A1 - Hydraulik-Zylinderanordnung - Google Patents

Hydraulik-Zylinderanordnung Download PDF

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Publication number
EP0135386A1
EP0135386A1 EP84306052A EP84306052A EP0135386A1 EP 0135386 A1 EP0135386 A1 EP 0135386A1 EP 84306052 A EP84306052 A EP 84306052A EP 84306052 A EP84306052 A EP 84306052A EP 0135386 A1 EP0135386 A1 EP 0135386A1
Authority
EP
European Patent Office
Prior art keywords
piston
end cap
cylindrical barrel
ram assembly
piston rod
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84306052A
Other languages
English (en)
French (fr)
Inventor
Raymond Garnet Hillier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Delibes Pty Ltd
Original Assignee
Delibes Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Delibes Pty Ltd filed Critical Delibes Pty Ltd
Priority claimed from AU32715/84A external-priority patent/AU577310B2/en
Publication of EP0135386A1 publication Critical patent/EP0135386A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423—Component parts; Constructional details
    • F15B15/1433—End caps

Definitions

  • the invention relates to a fluid actuated ram assembly.
  • Conventional fluid actuated ram assemblies include a piston, a piston rod attached to the piston, a cylinder or housing for the piston and opposed end caps attached to the cylinder.
  • one end cap or front end cap is removably or screw threadedly engageable with an adjacent end of the cylinder to facilitate removal of the piston and piston rod assembly'for maintenance purposes in relation to replacement of seals for example.
  • the other end cap or rear. end cap is welded to the cylinder.
  • There was also included an O-ring or sealing member located within the internal bore of the cylinder which was normally located in a groove provided in an external surface of the bearing or guide bush for the piston rod.
  • An object of the invention is therefore to provide a fluid actuated ram assembly which may alleviate one or more of the abovementioned disadvantages associated with the prior art.
  • the invention therefore provides a fluid actuated ram assembly including:
  • the cylindrical barrel may be movable relative to the piston but more preferably the piston is movable relative to the cylinder.
  • the ram assembly of the invention may be pneumatically actuated but is more suitably hydraulically actuated.
  • a fluid actuated ram assembly of the invention is double acting and therefore may include a front port as well as a rear port.
  • a ram assembly constructed in accordance with the invention may be single acting and thus the piston rod assembly may include a spring biassed return stroke.
  • the rear end cap is suitably welded or otherwise rigidly attached to an adjacent end of the cylinder. It is possible for the rear end cap to be screw threadedly attached to the cylinder but the rigid or integral attachment is preferable.
  • the end cap is plate like having a pair of opposed end surfaces and a continuous side surface or side wall.
  • a rear port is suitably provided which extends through the side wall into a central chamber in the rear end cap which is located adjacent to a piston assembly when the ram assembly is in the retracted position.
  • the rear end cap includes an outwardly extending peripheral rib located on an inner end surface thereof which may engage in a mating groove located on the piston when the ram assembly is in the retracted position.
  • the rib may have located on its top or outer surface a continuous groove accessible to fluid or oil from the central chamber.
  • the continuous groove is helical or in the form of a continuous spiral.
  • the piston which engages the internal surface of the cylinder suitably includes within its peripheral surface one or more seals and wear rings as is known in the art.
  • the piston rod suitably has a front portion of constant cross section, an intermediate tapered portion and a rear threaded section which engages within a mating screw threaded socket or passage in the piston.
  • the piston also includes in this particular-embodiment a tapered bore which mates with the tapered intermediate portion of the piston rod.
  • bonding agent is used to attach the piston rod to the piston in the threaded area so as to make the piston rod and piston in effect an integral assembly.
  • the cylindrical barrel also includes a front end cap releasably or screw threadedly attached to the front end of the cylinder.
  • the front end cap includes an outer end portion and a continuous side surface or wall surrounding a central aperture.
  • the front port may extend through the side wall of the front end cap.
  • the outer end portion of the front end cap will include one or more sealing members in an internal surface surrounding the central aperture.
  • the front end cap suitably also includes a tapered outer end surface surrounding a planar outer end surface which surrounds the aperture.
  • the front end cap may also include an inner end., portion including on an internal surface thereof a threaded part for engaging with a mating threaded part on the front end of the cylinder.
  • an adjustment shim or spacer suitably in the form of a ring member or collar having a gap or slot to facilitate attachment to the cylinder which in use allows the position of the front port to be varied radially relative to the rear port.
  • the guide bush may also include a peripheral outwardly extending rib on an inner surface thereof which may engage with a mating groove located on an adjacent end surface of the piston when the piston is in the extended position.
  • a mating groove located on an adjacent end surface of the piston when the piston is in the extended position.
  • the top or outer surface of the rib may include a continuous groove suitably in the form of a spiral or helix as previously described for the rear end cap which is accessible to fluid from the front port.
  • hydraulic ram assembly 10 comprising rear end cap 11 having opposed clevis plates 12 attached thereto.
  • End cap 11 is welded to cylindrical barrel 19 at 11A.
  • End cap 11 also includes rear port 13 and central cavity or chamber 14 connected to port 13 by passage 15. Port 13 is adapted to be closed by dust cap 16.
  • End cap 11 also has peripheral rib 17 as shown having a grooved outer surface 18.
  • piston rod 23 having a front portion 24 of constant cross section, an intermediate tapered portion 25 and rear end portion 26 which is screw threaded.
  • piston 27 having wear rings 21 and "J" seal and back-up ring assembly 22.
  • Piston 27 also has peripheral groove 20 for engaging with rib 17 as shown.
  • Piston 27 also has threaded socket 28 bonded to portion 26 of piston rod 23, tapered portion 29 for engaging with tapered portion 25 of piston rod 23, and peripheral groove 30.
  • Piston rod 23 as shown is attached to a pair of opposed clevis plates 31. It includes as best shown in FIG 5 grooves 28A for the wear rings and central groove 28B for the J seal previously described. There is also shown front end cap 32 having tapered end surface 33, planar end surface 34, central aperture 35 for receiving piston rod 23, front port 36, and inner end portion 37. There is also shown piston rod seal 38, piston rod wiper 39, and front end cap seal 40. Also shown is threaded part 41 engaging with mating screw threaded part 42 of cylindrical barrel.19. Also shown is groove 38A for seal 40.
  • piston rod guide bush 44 having angled longitudinal passageways 45 leading from front port 36 to gap 46 between inner end surface 47 of bush 44 and piston 27.
  • Bush 44 also has a peripheral rib 48 having a continuous spiral groove 49 located in a top surface thereof. Rib 48 engages with groove 30 of piston 27.
  • Guide bush 44 also includes inlet port 50 which communicates with longitudinal passageways 45 as well as intermediate passageways 51 and 52 leading to central annular reservoir 53. There is also shown central aperture 53A for insertion of piston rod 23.
  • adjustment shim 54 for radially adjusting the position of port 36 relative to port 13.
  • FIG 6 there is shown a modified ram assembly wherein similar features as described above in relation to the ram assembly of FIGS 1-5 are identified by the same reference numerals.
  • the main difference is that there is utilized a modified guide bush 55 having a plurality of longitudinal passages 56 leading from port 36A instead of angled passageways 45 described previously.
  • Intermediate passages 57 and annular central reservoir 58 There is also shown intermediate passages 57 and annular central reservoir 58.
  • Guide bush 55 also has spirally grooved surface 59 similar to spirally grooved surface 49 described previously which is shown particularly in FIG 7. Also shown is dust cap 43.
  • FIGS 9-10 there is shown clevis pin 60 having end grooves 61 for retention thereby by clip 62 for attachment of clevis plates 12 and 31 to a stationary part of a machine (not shown) and a movable part of the machine (not shown).
  • rod bush 44 also has outstanding shoulder 60 which abuts against the internal surface of front end cap 32.
  • piston rod 23 is useful in that it enables for ready insertion and alignment of rod 23 within piston 27 without the possibility of damaging any seals as was the case previously. This enables an extra seal between the piston rod 23 and piston 27 to be eliminated and ensures that the integral assembly of piston rod 23 and piston 27 is concentric so that resultant forces are transferred without any deflection.
  • the rod thread is of particularly large diameter to inhibit thread stretch and consequent piston failure.
  • front end cap 32 eliminates the possibility of trapped corrosives and water occurring in the ram assembly which in turn inhibits breakdown of the piston rod surface and destruction of seals. It also allows for obstacles to fall clear from becoming lodged between the front end of cylinder 19 and end cap 32 particularly when the assembly 10 is mounted in a vertical orientation.
  • rib 17 and mating groove 20 at the rear end of the assembly 10 and rib 48 and mating groove 30 ensures that "cushions" are provided for the piston when in the retracted or the extended position and thus the oil flow and hence piston speed may be retracted prior to full extension and retraction of the piston rod '23.
  • shim 54 enables the radial position of port 36 to be adjusted relative to port 13. This enables changes to be made during installation to overcome mis-alignment problems. Simple shims 54 cut to fractions of the front cap thread may be inserted between the front cap and cylinder end. No special tools or machining is therefore required.
  • seal 40 within the position as shown in the drawings is advantageous in that it is protected from corrosion because it is continually bathed in oil or hydraulic fluid. This enables the front cap 32 to be easily removed providing for convenient maintenance. Cap 32 may be easily removed even after long field use.
  • the thread is provided in the internal bore of cylinder 19 and thus is isolated from oil flow and subject to.corrosion making dismantling difficult and in some cases impossible. This particular feature also adds to the reliability of the cylinder 19 by increasing effective sealing when the barrel 19 "bulges" due to high transient shocks as described previously.
  • the rod bush 44 is suitably formed from high grade SG iron to overcome "grabbing" of the rod 23 in hot conditions.
  • Some conventional ram assemblies use a rod bush formed from aluminium or bronze which expands or “grows” in hot conditions resulting in a grabbed bush and subsequent leaking.
  • the aluminium or bronze bush also offers dissimilar metal corrosion and maintenance problems.
  • the use of SG iron substantially eliminates these problems as it has a very low coefficient of friction and is an excellent bearing material.
  • the bush 44 is also of greater length than conventional rod bushes and this offers greater rod support and thereby reduces side load shocks. SG iron also is unquestionably of higher loading capacity.
  • passageways 45 and 56 are also unique in that oil may travel along these passageways running the length of bush 44 and terminate directly at the surface in contact with piston 27.
  • the use of these passageways offers minimum pressure drop between port 36 or 36A and piston 27 and increases overall efficiency.
  • both ports 13 and 36 or 36A are located in end caps 11 and 32 respectively and thus are completely divorced from the precision honed cylinder tube 19.
  • Most conventional hydraulic ram assemblies have ports welded to the barrel as described previously and this may result in deformation and surface oxidation of the close tolerance honed diameter of tube 19 and thus leaves carbon and scale deposit on the interior of tube 19. This may be honed after welding. However most suppliers omit this additional finishing cost which is detrimental to life expectancy of the seals. This feature also allows for rapid change in cylinder stroke length by the end user.
  • the cylinder 19 and piston rod 23 are in effect the only non-standard components as all other components are interchangeable when required.
  • the invention also provides a method of assembly of the ram assembly using the following steps:
  • step (v) when separate from cylinder 19 forms an assembly which, when inserted into the cylinder 19 aligns the front end cap 32 and the abovementioned seals by use of peripheral rib 48 engaging in groove 30.
  • seal 40 clears the thread 41 on the cylinder tube 19 and locates the O-ring 40 on the external surface or outer diameter or tube 19 as thread 42 of cap 32 engages thread 41 on tube 19.
  • This sequence of assembly is brought about by the unique dimensioning and system of manufacture which guarantees systematic assembly and concentricity of components which fully protects the seals.
  • Seal 40 may also be inspected for imperfections in casting and/or machining operations without any special aids.
  • Rib 48 also is suitably located or dimensioned so that upon assembly of front end cap 32 and guide bush 44 and engagement within cylindrical barrel 19 the clearance of thread 41 by seal 40 as described above is enhanced.
  • shoulder 60 for guide bush 44 assists in precise and accurate location of front end cap 32 within cylindrical barrel 19 thus satisfying concentricity dimensional requirements.
  • piston rod seal 38 within an open ended recess 61 so that it is abutted by both rod bush 44 and front end cap 32 facilitates simplicity of machining operations in construction of ram assembly 10 and also for inspection of surface finish and measurement for size.
  • piston rod 23 also allows the piston rod 23 to be easily and rapidly assembled through rod wiper seal 39 and piston rod seal 38 with maximum guiding alignment while maintaining the absolute safety and preservation of the seals by the long guiding effect of taper 25. This ensures that assembly damage to the seals and rod bush due to sudden projections causing shearing and broaching damage of seals and rod bush as occurs in conventional ram assemblies is substantially eliminated.
  • the structural feature which is mainly responsible for the abovementioned advantages achievable by the present invention is the feature of the rod bush having the said longitudinal passage which may communicate with an adjacent surface of the piston and the fluid or front port located in the front end cap. This feature facilitates the location of seal 40 in the front end cap so that it is located in advance of screw threaded portions 41-42.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)
EP84306052A 1983-09-06 1984-09-04 Hydraulik-Zylinderanordnung Withdrawn EP0135386A1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPG125483 1983-09-06
AU1254/83 1983-09-06
AU32715/84A AU577310B2 (en) 1983-09-06 1984-09-04 Fluid actuated ram assembly

Publications (1)

Publication Number Publication Date
EP0135386A1 true EP0135386A1 (de) 1985-03-27

Family

ID=25622210

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84306052A Withdrawn EP0135386A1 (de) 1983-09-06 1984-09-04 Hydraulik-Zylinderanordnung

Country Status (1)

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EP (1) EP0135386A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0601736A1 (de) * 1992-12-11 1994-06-15 Parker Hannifin Plc Verbesserungen an Zylindern
EP1163979A1 (de) * 2000-06-14 2001-12-19 Hans Oetiker AG Maschinen- und Apparatefabrik Pneumatische Präzisions-Zange

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB981607A (en) * 1961-02-28 1965-01-27 Richard Breinlich Sealing and guiding arrangement for pistons in cylinders operating with hydraulic or pneumatic pressure media
US3232186A (en) * 1964-03-16 1966-02-01 Drilco Oil Tools Inc Piston and rod
FR2110390A1 (de) * 1970-10-13 1972-06-02 Int Harvester Co
FR2220700A1 (de) * 1973-03-08 1974-10-04 Poclain Sa
US4337692A (en) * 1980-07-25 1982-07-06 Cascade Corporation Fluid cylinder assembly having minimized outside diameter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB981607A (en) * 1961-02-28 1965-01-27 Richard Breinlich Sealing and guiding arrangement for pistons in cylinders operating with hydraulic or pneumatic pressure media
US3232186A (en) * 1964-03-16 1966-02-01 Drilco Oil Tools Inc Piston and rod
FR2110390A1 (de) * 1970-10-13 1972-06-02 Int Harvester Co
FR2220700A1 (de) * 1973-03-08 1974-10-04 Poclain Sa
US4337692A (en) * 1980-07-25 1982-07-06 Cascade Corporation Fluid cylinder assembly having minimized outside diameter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0601736A1 (de) * 1992-12-11 1994-06-15 Parker Hannifin Plc Verbesserungen an Zylindern
EP1163979A1 (de) * 2000-06-14 2001-12-19 Hans Oetiker AG Maschinen- und Apparatefabrik Pneumatische Präzisions-Zange
WO2001096071A1 (de) * 2000-06-14 2001-12-20 Hans Oetiker Ag Maschinen- Und Apparatefabrik Pneumatische präzisions-zange
US7107814B2 (en) 2000-06-14 2006-09-19 Hans Oetiker Ag, Maschinen Und Apparatefabrik Pneumatic precision pliers

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): AT BE DE FR GB IT NL SE

17P Request for examination filed

Effective date: 19850924

17Q First examination report despatched

Effective date: 19860704

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: DELIBES PTY. LTD.

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19880204

RIN1 Information on inventor provided before grant (corrected)

Inventor name: HILLIER, RAYMOND GARNET