US3824895A - Fluid ram provided with means for braking the ram piston at the end of its stroke - Google Patents

Fluid ram provided with means for braking the ram piston at the end of its stroke Download PDF

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Publication number
US3824895A
US3824895A US00353676A US35367673A US3824895A US 3824895 A US3824895 A US 3824895A US 00353676 A US00353676 A US 00353676A US 35367673 A US35367673 A US 35367673A US 3824895 A US3824895 A US 3824895A
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United States
Prior art keywords
piston
cylinder
conduit
chamber
auxiliary
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Expired - Lifetime
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US00353676A
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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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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F3/00—Devices, e.g. jacks, adapted for uninterrupted lifting of loads
    • B66F3/24—Devices, e.g. jacks, adapted for uninterrupted lifting of loads fluid-pressure operated
    • B66F3/25—Constructional features
    • B66F3/32—Constructional features with means for avoiding excessive shocks on completion of movements
    • 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

  • the invention provides a fluid ram comprising:
  • a shock-absorption apparatus for the end-of the piston stroke having an auxiliary chamber which, when the piston is adjacent to one of the ends of the cylinder and is approaching its extreme position corresponding to the said end, is initially in communication with the delivery conduit and is then substantially isolated from the said delivery conduit,
  • a communication conduit which is formed in the piston-piston rod assembly and connects the inlet chamber to the delivery conduit;
  • the communication conduit passes through the piston for determining the opening of the controlled valve.
  • the ram also includes:
  • a calibrated valve which is arranged in the auxiliary conduit so as to limit the pressure of the fluid in the auxiliary chamber to a given value, while allowing for possible passage of the fluid from the said auxiliary chamber to the delivery conduit.
  • this ram When this ram is of the double-action type, it is may be provided with another auxiliary chamber which, when the piston is adjacent to the other end of the cylinder and is approaching its extreme position corresponding to the said other end, is initially in communication with the inlet conduit, and is then substantially isolated from the inlet conduit, and which, in this latter arrangement, is placed in at least partial communication with the communication conduit through the said controlled valve, which then acts as another calibrated valve.
  • This other auxiliary chamber is preferably defined by an auxiliary piston, which is hollowed out, is arranged in the inlet chamber, and is mounted slidably relative to the ram piston.
  • a non-return valve is inserted between this other auxiliary chamber and the inlet chamber so as to allow passage of fluid from the inlet chamber to the said other auxiliary chamber.
  • FIG. 1 is an axial section of a first ram in accordance
  • FIG. 2 is an axial section of a second rain in accordance with the invention
  • FIG. 3 shows a third embodiment, in axial section.
  • Theram shown in FIG. 1 consists of a cylinder 1 and a piston 2 having two faces 20 and 2b, to which is linked a piston rod 3. Seals 4 are inserted between piston 2 and cylinder 1 and between the piston rod 3 and cylinder 1.
  • Piston 2 is mounted slidably in cylinder 1 and, with the said cylinder, defines with its face 2a a chamber 5, known as the delivery chamber, and with its face 2b a chamber 6, known as the inlet chamber.
  • the pressurised fluid is selectively admitted to a first of these two chambers, the second of these two chambers itself being placed in communication with a discharge reservoir.
  • the terms used for chambers 5 and 6 are, therefore, only for convenience, but do not necessarily describe the function of the corresponding chamber.
  • Piston rod 3 in unitarily connected to the piston 2 at a radially extending surface 7 defining one end of a first portion of the piston 2 having a relatively small diameter of such dimension as to be matingly insertable in a first portion 8 of cylinder 1 which is also of relatively small diameter.
  • the end portion of piston 2 opposite the connection to rod 3 comprises a second portion of the piston which is of larger diameter dimensioned to be matingly received in a larger diameter portion of the casing 1 extending to the right of a radial surface 8a as illustrated in FIG. 1. Consequently, when the piston moves to the left to the dotted line position 7a illustrated in FIGS. 1 and 2, a first auxiliary chamber 9 is formed.
  • a conduit connects the first portion 8 of the cylinder 1 to the exterior ofthe cylinder 1.
  • a cavity 13 is formed in the piston 2 and the piston rod 3.
  • a withdrawable closure has been provided for cavity 13.
  • a conduit 16 formed in piston rod 3 connects the first auxiliary chamber 9 to piston 14, at least in posi tion 16a which it occupies, when chamber 9is effectively formed.
  • Valve is arranged in a conduit 17, which connects face 2b of piston 2 to chamber 33 defined by one end 14a of control piston 14.
  • valve 15 is slidably guided by guides 18 bearing on a cylindrical surface 19.
  • conduits 19a pass through piston 14, and connect its two faces 14a and 14b. They run into a chamber 20 which, when the first auxiliary chamber 9 is formed, opens through a conduit 21 into housing 8.
  • conduits 17, 19a and 21 together constitute a communication conduit, which connects faces 2a and 2b of piston 2.
  • a spring 22 tends to hold valve 15 against its seat and its influence is in a direction opposite the direction of the force on the control piston 14 created by the pressure of fluid in the first auxiliary chamber 9.
  • conduit 16 connects the first auxiliary chamber 9 to a chamber 20a defined by a portion of face 14a of piston 14.
  • a conduit 11a connects the said chamber 20a to chamber 20.
  • Conduit 11a runs into chamber 20 through a bore 34.
  • a valve 12a guided axially in bore 34, has a calibrated spring, which tends to close it against the antagonistic influences of the pressure of the fluid contained in chamber 20a. In this way, a passage is formed between auxiliary chamber 9 and housing 8, through conduits 16, 11a and 21, bore 34 and valve 12a.
  • FIG. 2 shows a simplified, equivalent embodiment of the assembly of conduits 16, 11a and 21 and valve 12a.
  • auxiliary conduit 11 which connects the first auxiliary chamber 9 to the smaller diameter portion 8, being formed in piston rod 3.
  • a calibrated valve 12 consisting of a ball-bearing and a spring for holding this ball-bearing in position, is arranged in auxiliary conduit 11 and allows passage of fluid from the first auxiliary chamber 9 to delivery conduit 10.
  • a ram is shown which is similar to the ram of FIG. 2, while being provided with the following complementary apparatus.
  • Piston 2 has a cylindrical portion 23 adjacent to its face 2b, or which an auxiliary piston 24 is slidably mounted.
  • Piston 24 has an internal cavity 25 which, in cooperation with conduit 17, forms a second auxiliary chamber 26.
  • a spring 27 returns piston 24 to a position which gives the maximum volume to chamber 26, while a stop 28 limits the clearance of the said piston 24.
  • a non-return valve 29 is arranged on the base 32 of I. piston 24 and connects the second auxiliary chamber 26 to chamber 6 of the ram.
  • the latter chamber is deconduit 31, known as an inlet conduit, connects chamber 6 to the outside of cylinder 1.
  • the case in question is one in which the pressurised fluid is admitted to chamber 6 and acts on face 2b of piston 2, in the direction caus ing a decreace in the value of the volume of chamber 5.
  • the fluid contained in this chamber 5 is delivered but of cylinder 1 through conduit 10. Shoulder 7 then reaches 7a, which causes a considerable deceleration of the piston 2, the fluid contained in chamber 9 only being able to escape, in principle, through the passage of small cross section between shoulder 7a and the bore of housing 8. It will be noted in the first place that, when piston 2 is moved until the'pressure of the fluid contained inchamber 9 undergoes a considerable increase, the said fluid is conveyed by conduit 16 (or 16a) to act on piston 14, against the influence of spring 22.
  • valve 12a is so selected that the valve opens under the influence of the pressure of the fluid in chamber 9, when the said pressure reaches the above-mentioned critical value. Opening of valve 12a therefore enables the fluid in chamber 9 to escape through conduits 16, 11a and 21 into conduit 10 and avoids any risk of excess pressure.
  • conduits 16, llaand 21 and valve 12a in piston rod 3 itself in addition to providing a compact ram and satisfactory protection of the valve, also completely eliminates the possibility of any leak due to the presence of valve 12a.
  • FIG. 3 comprises a double-acting cylinder in which the piston 2 is further modified to provide means for cushioning the stroke of the piston as it approaches the head 30 of the cylinder.
  • This result provides cushioning for the end of the piston stroke at both ends of the cylinder and is achieved by the provision of a second auxiliary chamber 26 formed in the interior of a hollow auxiliary piston 24 and communicating with a normally closed valve 15 on its inner end.
  • a slide support means 23 extending axially from the face 2b of piston 2.
  • a radial lug 28 on the outer end of the slide support means 23 provides a stop for limiting the movement of the hollow auxiliary piston 24 to the right as viewed in FIG. 3.
  • the second auxiliary chamber 26 provided on the interior of piston 24 is connected by a non-return valve 29 to the chamber 6 so as to allow the passage of fluid from the chamber 6 to the second auxiliary chamber 26.
  • a coil compression spring 27 acts upon piston 24 to move the piston to its extreme righthand position illustrated in FIG. 3 in which position the auxiliary chamber 26 has its largest possible volume.
  • valve 15 serves to limit the maximum pressure in chamber 26 in essentially the same manner as valve 12 operates to vent pressure from the chamber 9 of the first embodiment. Consequently, valve 15 provides controlled communication with the high pressure side of the cylinder for cushioning the piston movement.
  • a hydraulic ram comprising a cylinder having a first end portion and a second end portion, said second end portion being of a larger diameter than said first end portion, a piston mounted in said cylinder, said piston comprising a first piston portion of relatively small diameter dimensioned to matingly fit in the first end portion of said cylinder and a second piston portion of larger diameter dimensioned to matingly fit in the second end portion of said cylinder, piston rod means extending from said first end portion and being of a smaller diameter than said first piston portion, said piston rod means extending from said cylinder outward through seal means in an end wall of said cylinder, a delivery conduit extending through said cylinder wall and having an inner end defining an inlet communicating with outermost end portions of said first end portion of said cylinder, an auxiliary conduit extending through a portion of the piston rod and the piston providing communication between the outer periphery of the first piston portion and the outer periphery of a portion of the piston rod spaced from said piston in communication with said first cylinder portion as the piston moves toward the
  • a fluid ram comprising a cylinder, a piston-piston rod assembly slidably mounted in said cylinder, an inlet chamber and a delivery chamber in the cylinder each respectively constituting the portions of the cylinder on opposite sides of the piston, an inlet conduit, a delivery conduit, said inlet conduit and said delivery conduit each being respectively connected to first and second opposite end portions of the cylinder for communication with the inlet and delivery chambers, shock absorbing means including an auxiliary chamber in said cylinder operable as the piston moves through an intermediate position in communication with said delivery conduit so that movement of the piston moves fluid from the auxiliary chamber to the delivery conduit with subsequent movement of the piston toward its extreme end position in the first end of the cylinder terminating communication of the auxiliary chamber with the delivery conduit to substantially isolate the auxiliary chamber, a communication conduit formed in the pistonpiston rod assembly extending between and connecting said inlet chamber to said delivery conduit, a control valve mounted in said communication conduit, an auxiliary conduit formed in the piston-piston rod assembly connecting the auxiliary chamber and the delivery conduit, a pressure
  • control piston for adjusting the opening of the control valve is mounted in a cylindrical portion of the auxiliary conduit.
  • said ram is of the double-action type and additionally including a second auxiliary chamber which, when the piston is adjacent to the second end portion of the cylinder and is closely approaching its extreme possible position in the second end portion of the cylinder, is initially in communication with the inlet conduit and is subsequently isolated from the inlet conduit by a portion of the cylinder and valve means providing at least partial communication of said second auxiliary chamber with the communication conduit through said control valve.
  • said second auxiliary chamber is formed in a hollow auxiliary piston mounted in said inlet chamber and additionally including slide support means on said piston slidably supporting said auxiliary piston and a non-return valve connected between said second auxiliary chamber and the inlet chamber so as to allow passage of fluid from the inlet chamber to said second auxiliary chamber.
US00353676A 1972-05-03 1973-04-23 Fluid ram provided with means for braking the ram piston at the end of its stroke Expired - Lifetime US3824895A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7215721A FR2182672B1 (ja) 1972-05-03 1972-05-03

Publications (1)

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US3824895A true US3824895A (en) 1974-07-23

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US00353676A Expired - Lifetime US3824895A (en) 1972-05-03 1973-04-23 Fluid ram provided with means for braking the ram piston at the end of its stroke

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US (1) US3824895A (ja)
JP (1) JPS4941779A (ja)
AR (1) AR194175A1 (ja)
BE (1) BE797981A (ja)
BR (1) BR7303155D0 (ja)
DE (1) DE2322354A1 (ja)
ES (1) ES414342A1 (ja)
FR (1) FR2182672B1 (ja)
GB (1) GB1378363A (ja)
IT (1) IT980924B (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5042885A (en) * 1989-11-16 1991-08-27 General Motors Corporation Integrated anti-lock braking and traction control system
CN108799395A (zh) * 2017-04-29 2018-11-13 益阳天华两栖车艇有限公司 一种可伸缩筒柱式减震器

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5498991U (ja) * 1977-12-26 1979-07-12
JPS54103279A (en) * 1978-01-31 1979-08-14 Ikeda Denki Kk Device for starting discharge lamp
DE3046755A1 (de) * 1980-12-12 1982-07-22 Wabco Steuerungstechnik GmbH & Co, 3000 Hannover Einrichtung zur endabbremsung des arbeitskolbens eines doppeltwirkenden arbeitszylinders
DE29517364U1 (de) * 1995-11-02 1996-01-04 Festo Kg Vorrichtung zur Endlagendämpfung
DE10118867C1 (de) * 2001-04-18 2003-01-30 Festo Ag & Co Dämpfungsvorrichtung sowie damit ausgestattetes pneumatisches System
ES2230935A1 (es) * 2002-03-13 2005-05-01 Antonio Orantes Zambrano Dispositivo de apertura y cierre para puertas.
DE10261412A1 (de) * 2002-12-30 2004-07-22 Bosch Rexroth Teknik Ab Pneumatikzylinder mit Dämpfungsmitteln
EP1998054B1 (de) * 2007-05-24 2014-08-13 Parker Origa Holding AG Pneumatikzylinder mit einer selbsteinstellenden Endlagendämpfung und entsprechendes Verfahren

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259026A (en) * 1964-11-05 1966-07-05 Parker Hannifin Corp Fluid pressure motor with unloading valve
US3605409A (en) * 1969-04-01 1971-09-20 Hydra Power Inc Hydraulic actuator

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3592108A (en) * 1969-02-07 1971-07-13 Borje Oscar Rosaen Fluid cylinder

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259026A (en) * 1964-11-05 1966-07-05 Parker Hannifin Corp Fluid pressure motor with unloading valve
US3605409A (en) * 1969-04-01 1971-09-20 Hydra Power Inc Hydraulic actuator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5042885A (en) * 1989-11-16 1991-08-27 General Motors Corporation Integrated anti-lock braking and traction control system
CN108799395A (zh) * 2017-04-29 2018-11-13 益阳天华两栖车艇有限公司 一种可伸缩筒柱式减震器

Also Published As

Publication number Publication date
DE2322354A1 (de) 1973-11-22
IT980924B (it) 1974-10-10
AR194175A1 (es) 1973-06-22
BR7303155D0 (pt) 1974-06-27
ES414342A1 (es) 1976-02-01
FR2182672B1 (ja) 1975-03-21
GB1378363A (en) 1974-12-27
FR2182672A1 (ja) 1973-12-14
BE797981A (fr) 1973-07-31
JPS4941779A (ja) 1974-04-19

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