US3786724A - Device limiting the delivery output of a jack - Google Patents

Device limiting the delivery output of a jack Download PDF

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Publication number
US3786724A
US3786724A US00249879A US3786724DA US3786724A US 3786724 A US3786724 A US 3786724A US 00249879 A US00249879 A US 00249879A US 3786724D A US3786724D A US 3786724DA US 3786724 A US3786724 A US 3786724A
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United States
Prior art keywords
chamber
deformable member
piston
complementary
walls
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Expired - Lifetime
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US00249879A
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English (en)
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L Martin
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Poclain SA
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Poclain SA
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    • 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
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • F15B15/222—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke having a piston with a piston extension or piston recess which throttles the main fluid outlet as the piston approaches its end position

Definitions

  • ABSTRACT A device for limiting the delivery output of a jack having a complementary chamber of substantially smaller diameter opening into the end of a main delivery chamber, the complementary chamber having a delivery conduit, a deformable member coupled in translation with a piston rod and being capable of abutting the piston, the deformable member being capable of penetrating into the complementary chamber from the main delivery chamber and being of slightly smaller diameter and having complementary walls with respect to the walls of the complementary chamber to form a passage between the end of main delivery chamber and the complementary chamber, the deformable member being deformed by fluid pressure to increase the transverse section of the passage between the walls of the deformable member and the complementary chamber.
  • the present invention relates to a device for limiting the delivery output of a jack.
  • the fluid which remains to be delivered is laminated in a complementary chamber of section smaller than the section of the main delivery chamber. In this way, the delivery output of the jack is limited.
  • At least one of the two members, element in the form of a shoulder and walls defining the complementary chamber may be deformed under the action of the pressure of the fluid, whilst said possible deformation corresponds to an increase in the section of the passage connecting the main chamber to the complementary chamber, said passage itself being constituted by the volume defined by the parts of walls of the element and the complementary chamber which are opposite one another and which are included between the extreme cross-sections of the main chamber and the shoulder of the element.
  • the deformable member is advantageously made of an elastic material.
  • this member is constituted by a ring, of which the walls parallel to the axis of the cylinder are deformable, and which defines with the walls of the complementary chamber a passage for the fluid, the section of which varies as a function of the stresses due to the pressure of said fluid.
  • the deformable member is constituted by a ring of revolution whose generatrix has an initial section which may be deformed into a configuration which is in relationship with the value of the delivery output corresponding to the instantaneous position of the piston of the jack in the cylinder.
  • FIG. 1 is an axial section through a jack provided with a known output limiter.
  • FIG. 2 is a part axial section through a jack providedwith an output limiter according to the invention.
  • FIG. 3 is a variant of the limiter shown in FIG. 2;
  • FIG. 4 shows the curves relative to the deceleration of the piston obtained by adapting the limiters of FIGS. 2 and 3 respectively.
  • FIG. 1 shows a jack of known type, constituted by a cylinder 1 inside which a piston 2 is mounted to slide along axis 3 of said cylinder 1.
  • a sealing joint 4 is interposed between the wall of the cylinder 1 and the piston 2.
  • a piston rod 5 is integral with the piston 2 and traverses the base 6 of the cylinder 1 with the interposition of a sealing joint 7. It will be noted that a chamber 8, called main delivery chamber, is defined by the piston 2 and the walls of the cylinder 1, and communicates with the outside of the jack by a delivery conduit 9. I
  • a complementary cylindrical chamber 10, coaxial to the axis 3, is disposed at the end of the main chamber 8, whilst the conduit 9 opens out into said chamber 10.
  • the section of chamber 10, which is that of a circular crown, of large diameter D and. of small diameter equal to that of the rod 5, is notably smaller than that of the main chamber 8.
  • a shoulder 11, of diameter d slightly smaller than diameter D is integral in translation with the piston 2 and, being located on the side of the face 2a of said piston 2, which defines the main chamber 8, and being disposed coaxially to the axis 3, is capable of penetrating into the chamber 10, at the end of stroke of the piston 2.
  • FIG. 2 shows most of the elements already referenced in FIG. 1.
  • the shock-absorbing element is in the position in which it effectively acts to reduce the speed of displacement of the piston of the jack.
  • the piston 2 is maintained integral in translation with the piston rod 5, abutting, by its face 2a, on a shoulder 12 integral with said rod 5, whilst a nut 13 cooperates with the threaded end 14 of the rod 5 in order to maintain the face 2a in contact with the shoulder 12.
  • the shoulder 11 is constituted by the extreme cross-section of a ring 15, which is integral in translation with the piston rod 5, being fixed axially between a shoulder 16 of said rod 5, and the face 2a of the piston 2.
  • the ring 15 is cylindrical and defines an inner volume 18 by its walls 17 parallel to axis 3, as well as by its wall terminating by shoulder 11, and with the face 2a of the piston 2.
  • the ring 15 is thus distinct from the rod 5 of the piston and is interchangeable. Moreover, it is made of an elastic material and may, under the effect of the pressure of the fluid contained in the chamber 8, be deformed elastically, in the sense of an instantaneous, provisional reduction in the diameter d of the outer faces of the walls 17. Finally, a conduit 19 traverses one of the walls of the ring 15 and connects the inner volume 18 to the complementary chamber 10.
  • the above-mentioned ring is replaced by a ring 15a, the outer walls 17a of which are defined by a non-cylindrical surface of revolution.
  • the deformations of the rings 15 or 15a may vary as a function of the actual position of the piston 2 in the cylinder 1, said position being referenced in the present case by the distance L which separates the end cross-section 8a of the chamber 8 from the shoulder 11.
  • FIG. 4 shows the curves l5 and 15a providing the correspondence between the delivery output Q of the fluid, thus the speed V of the piston 2, and the distance L, for jacks provided, one, with the ring 15, the other with the ring 150.
  • the value reached by the pressure is a function of a number of parameters and is governed by the physical laws of fluid flow between narrow walls. Mention will be made, inter alia, of the influences of the viscosity of the fluid along the narrow passage, the output of fluid from chamber 8 to chamber 10, the difference in the diameters D and d. In certain cases, the value reached by the pressure is considerable and the stresses of the pressure on the walls of the cylinder 1 bring about a permanent deformation of said cylinder and consequently the destruction of the jack, no longer by mechanical shock, but by excessive manometric stress.
  • the ring 15 is obviously advantageous to have provided the ring 15 to be removable, this facilitating possible replacement thereof, and to have chosen said ring to be of elastic material, this, in the majority of cases, avoiding permanent deformation of said ring, and thus avoiding replacement itself.
  • conduit 19 enables the fluid to be present on the two sides of the ring 15, and thus obtains a balancing of the pressures during established operation.
  • This arrangement therefore permits a choice of moderate dimensions for the ring 15.
  • the transfer of fluid through said conduit 19, taking into account the deformation of the ring 15, brings about only a small difference in pressure of the fluids contained in the chambers 10 and 18, being given the value of the variation of the volume of the chamber 18, which is very low.
  • FIG. 2 the embodiments of either FIG. 2 or FIG. 3 may be adopted, this making it possible, as a function of the instantaneous position of the piston 2, referenced by distance L, to obtain a more or less energetic braking, as shown in FIG. 4.
  • a device for limiting the delivery output of a jack having a cylinder, a piston mounted in said cylinder, said piston and cylinder forming a main delivery chamber, a piston rod extending from said piston through said main delivery chamber, said device comprising a complementary chamber formed in said cylinder at the end thereof, said complementary chamber opening into the end of said main chamber and having a crosssection perpendicular to the axis of the cylinder substantially smaller than the cross-section of said main chamber, said complementary chamber having a delivery conduit, a deformable member coupled in translation with said piston rod and being mounted on the side of said piston defining the main delivery chamber and being capable of abutting said piston, said deformable member being capable of penetrating into said complementary chamber from said main delivery chamber, said deformable member having walls and a shoulder at its end opposite said piston, said deformable member having a cross-section perpendicular to the axis of the cylinder slightly smaller than the cross-section of the complementary chamber and the walls of said deformable member being of complementary form with respect
  • a device according to claim 1 wherein the deformable member is made of an elastic material.
  • a device wherein the deformable member is constituted by a substantially cylindrical ring, of which the walls parallel to the axis of the cylinder are deformable, and which defines with the walls of the complementary chamber a passage of fluid, the section of which varies as a function of the stresses due to the pressure of said fluid.
  • a device according to claim 1 wherein the deformable member is constituted by a ringof revolution, the generatrix of which possesses an initial section which may be deformed into a configuration which is in relationship with the value of the delivery output corresponding to the instantaneous position of the piston of the jack in the cylinder.
  • a device wherein said deformable member is separable from said jack, whereby said deformable member is interchangeably replaceable.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)
US00249879A 1971-05-24 1972-05-03 Device limiting the delivery output of a jack Expired - Lifetime US3786724A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7118647A FR2138342B1 (fr) 1971-05-24 1971-05-24

Publications (1)

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US3786724A true US3786724A (en) 1974-01-22

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ID=9077498

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US00249879A Expired - Lifetime US3786724A (en) 1971-05-24 1972-05-03 Device limiting the delivery output of a jack

Country Status (7)

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US (1) US3786724A (fr)
BE (1) BE782245A (fr)
DE (1) DE2223967A1 (fr)
ES (1) ES403091A1 (fr)
FR (1) FR2138342B1 (fr)
GB (1) GB1366457A (fr)
IT (1) IT958847B (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4352318A (en) * 1980-03-06 1982-10-05 Miller Fluid Power Corporation Expandable cushion plunger for piston and cylinder devices
US4635536A (en) * 1983-09-19 1987-01-13 Miller Fluid Power Corporation Cylinder locking apparatus
EP1113185A2 (fr) * 1999-12-30 2001-07-04 Diebolt International, Inc. Ressort à impact réduit
EP1677010A1 (fr) * 2005-01-03 2006-07-05 Volvo Construction Equipment Holding Sweden AB Dispositif amortisseur pour un vérin
AT504592B1 (de) * 2007-05-24 2008-06-15 Hoerbiger Origa Holding Ag Pneumatikzylinder mit einer und verfahren zur selbsteinstellenden endlagendämpfung
US20080289920A1 (en) * 2007-05-24 2008-11-27 Hoerbiger-Origa Holding Ag Pneumatic cylinder with a self-adjusting end position damping arrangement, and method for self-adjusting end position damping

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4134063A1 (de) * 1991-10-15 1993-04-22 Festo Kg Linearantrieb
JP2598210B2 (ja) * 1992-12-01 1997-04-09 エスエムシー株式会社 シリンダ装置
DE19522966A1 (de) * 1995-06-27 1997-01-02 Knorr Bremse Systeme Hydropneumatischer Kupplungskraftverstärker, insbesondere für Kraftfahrzeuge
DE10305850A1 (de) * 2003-02-12 2004-08-26 Bosch Rexroth Ag Druckmittelbetätigter Arbeitszylinder

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2493602A (en) * 1947-12-31 1950-01-03 Vance C Sterrett Pressure fluid motor
US2642845A (en) * 1950-12-20 1953-06-23 Westinghouse Air Brake Co Piston cushioning apparatus
FR1047170A (fr) * 1951-04-28 1953-12-11 Organes des machines et leurs commandes combinées; électrique, pneumatique, hydraulique ou mécanique
US2884903A (en) * 1957-09-13 1959-05-05 Westinghouse Air Brake Co Cushioned piston assemblage for cylinders
US2911952A (en) * 1955-04-28 1959-11-10 Renault Double-acting pneumatic jack

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2493602A (en) * 1947-12-31 1950-01-03 Vance C Sterrett Pressure fluid motor
US2642845A (en) * 1950-12-20 1953-06-23 Westinghouse Air Brake Co Piston cushioning apparatus
FR1047170A (fr) * 1951-04-28 1953-12-11 Organes des machines et leurs commandes combinées; électrique, pneumatique, hydraulique ou mécanique
US2911952A (en) * 1955-04-28 1959-11-10 Renault Double-acting pneumatic jack
US2884903A (en) * 1957-09-13 1959-05-05 Westinghouse Air Brake Co Cushioned piston assemblage for cylinders

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4352318A (en) * 1980-03-06 1982-10-05 Miller Fluid Power Corporation Expandable cushion plunger for piston and cylinder devices
US4635536A (en) * 1983-09-19 1987-01-13 Miller Fluid Power Corporation Cylinder locking apparatus
EP1113185A2 (fr) * 1999-12-30 2001-07-04 Diebolt International, Inc. Ressort à impact réduit
EP1113185A3 (fr) * 1999-12-30 2001-09-26 Diebolt International, Inc. Ressort à impact réduit
US6491143B1 (en) 1999-12-30 2002-12-10 Diebolt International, Inc. Low impact gas spring
EP1677010A1 (fr) * 2005-01-03 2006-07-05 Volvo Construction Equipment Holding Sweden AB Dispositif amortisseur pour un vérin
AT504592B1 (de) * 2007-05-24 2008-06-15 Hoerbiger Origa Holding Ag Pneumatikzylinder mit einer und verfahren zur selbsteinstellenden endlagendämpfung
US20080289920A1 (en) * 2007-05-24 2008-11-27 Hoerbiger-Origa Holding Ag Pneumatic cylinder with a self-adjusting end position damping arrangement, and method for self-adjusting end position damping
US8596431B2 (en) 2007-05-24 2013-12-03 Parker Origa Holding Ag Pneumatic cylinder with a self-adjusting end position damping arrangement, and method for self-adjusting end position damping

Also Published As

Publication number Publication date
ES403091A1 (es) 1975-04-16
BE782245A (fr) 1972-08-16
FR2138342A1 (fr) 1973-01-05
DE2223967A1 (de) 1972-12-07
GB1366457A (en) 1974-09-11
FR2138342B1 (fr) 1974-03-08
IT958847B (it) 1973-10-30

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