EP0182927A1 - Hydraulischer Hebebock mit Hubbegrenzung - Google Patents

Hydraulischer Hebebock mit Hubbegrenzung Download PDF

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Publication number
EP0182927A1
EP0182927A1 EP84114236A EP84114236A EP0182927A1 EP 0182927 A1 EP0182927 A1 EP 0182927A1 EP 84114236 A EP84114236 A EP 84114236A EP 84114236 A EP84114236 A EP 84114236A EP 0182927 A1 EP0182927 A1 EP 0182927A1
Authority
EP
European Patent Office
Prior art keywords
piston
rod
cylinder
shoulder
bearing
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.)
Granted
Application number
EP84114236A
Other languages
English (en)
French (fr)
Other versions
EP0182927B1 (de
Inventor
Claude Pestourie
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.)
F Rassant Sa Ets
Original Assignee
F Rassant Sa Ets
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 F Rassant Sa Ets filed Critical F Rassant Sa Ets
Priority to DE8484114236T priority Critical patent/DE3474134D1/de
Priority to EP19840114236 priority patent/EP0182927B1/de
Publication of EP0182927A1 publication Critical patent/EP0182927A1/de
Application granted granted Critical
Publication of EP0182927B1 publication Critical patent/EP0182927B1/de
Expired legal-status Critical Current

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Classifications

    • 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
    • F15B15/24—Other details, e.g. assembly with regulating devices for restricting the stroke

Definitions

  • the invention relates to hydraulic jacks, constituted by a vertical hydraulic cylinder surrounded by a reserve of coaxial oil and provided with a hand pump, sucking in the reserve and discharging into the base of the jack to ensure the rise, with in in addition to a tap or relief valve allowing the descent.
  • the piston of the jack is provided with a lip seal of a shape derived from the classic pump leather, and the hydraulic stroke limiting device is constituted simply by a hole drilled in the wall of the cylinder of the jack, in the vicinity of the high point of its travel, to make the interior of the cylinder communicate with the reserve when this hole is exposed by the lip of the piston seal.
  • Such a device is relatively effective but has the drawback that the seal lip is caught up in the pressure difference towards the inside of the hole, at the same time as its up and down movement occurs, so that the seal quickly deteriorates, especially if the seal is rubber.
  • a leather seal is more often used which is more expensive, less waterproof, and which is nevertheless caught in the hole; this results in the tearing of particles of leather which are then suspended in the oil, which alters the functioning of the whole jack, in particular at the level of the valves of the pump.
  • Another minor drawback of the device with a lateral hole is that an additional stroke must be provided at the end of the stroke which is substantially equal to the diameter of the hole in order to be sure of discharging.
  • the object of the invention is to eliminate the above drawbacks by providing a stroke limiting device in which the cylinder has no lateral hole intercepted by the lip of the piston seal in its stroke, in order to ensure a long service life. gasket, even made of rubber in a more usual way, and which furthermore requires no additional stroke for the piston.
  • the invention essentially consists in mounting the piston on its rod in a movable manner with a determined axial clearance, and in interposing between a flat shoulder of the rod and the top of the piston a flat seal which ensures sealing in normal operation , by providing a shoulder on the upper bearing of the jack to stop the piston and not the rod at the end of the stroke, in such a way that said seal is eliminated, the pressure being thus released by the upper end of the cylinder, not reached by the main joint, thanks to appropriate grooves and holes.
  • the jack 1 usually comprises a cylinder 2, closed at its lower end by the base 3 of the device and open at its upper end.
  • a piston 4 provided with a lip seal 5 and extended at its upper part by a rod 6 which passes through the seal in a sealed manner, using a seal 7 upper 8 of the jack screwed onto the upper end of the cylinder 2.
  • the upper end of the rod 6 of the jack may further end in the usual manner by a support piece 9 comprising a threaded lower rod 10 which is screwed freely in the rod 6 in order to allow manual adjustment of the initial height of the jack.
  • the pressureless oil reserve is located at 13 between the cylinder 2 and the casing 11.
  • a hand pump actuated by a lever not shown and constituted by a plunger 14 sliding in a bore 15 of the base, with in addition communication channels and suction and discharge valves, shown in fig. 1 and not referenced, to allow the pump to draw the oil from the reserve 13 and to discharge it inside the cylinder 2 through the base thereof.
  • a tap or relief valve 16 controlled by hand to allow, with an adjustable pressure drop, the communication between the interior of the cylinder 2 and the reserve 13 in order to ensure the descent control at the desired speed, after the hand pump 14 has produced the rise of the rod 6.
  • the piston 4 instead of the lateral discharge hole usually provided in the wall 2, provision is made to mount the piston 4 on the rod 6 in a movable manner with a determined axial play.
  • the rod 6 can be extended by a reduced portion 17 on which the piston 4 threads, provided for this purpose with a central bore 18 with a diameter slightly larger than the outside diameter of 17 so to allow both a play and a passage of oil.
  • a summary stop constituted for example by a simple circlip 19 placed in a groove 20 near the end of the reduced part 17, makes it possible to prevent the piston 4 from completely detaching from its rod 6.
  • a flat seal 21 coming to bear directly on the flat shoulder 22 of the rod 6 around its reduced part 17.
  • a vulcanized fiber joint of sufficient hardness preferably 40 to 100 Rockwells, is used to maintain an operating pressure of 1800 to 2500 bars.
  • this seal 21 is preferably placed in a groove made in the piston 4 or in the shoulder 22, this groove naturally being of a depth less than the thickness of the uncompressed seal.
  • the device is arranged so that the screw connection between the upper bearing 8 and the upper end of the cylinder 2 is not sealed, for example by not screwing it to the end, as shown in FIG. 2, so as to provide an annular space 23, and further providing one or more orifices 24 for communication between this space 23 and the reserve 13.
  • the outside diameter of the rod 6, that is to say therefore the inside diameter of the bore 25 of the upper bearing 8, is slightly less than the outside diameter of the piston 4 and the bore inside 26 of cylinder 2, so that the piston 4 does not run the risk of passing through the bore 25.
  • the piston 4 reaches the top of its travel, as shown in FIG. 3, it abuts on the shoulder 27 of the upper bearing 8 surrounding the bore 25, which produces a slight increase in the pressure in the cylinder 2 in a ratio which is the square of the ratio of the diameters of the bore 26 and of the seal 21, whereby the rod 6 continues to rise with an extremely short stroke, just sufficient to allow the decompression of the seal 21 and the escape of the oil through the interval 28, greatly exaggerated in FIG.
  • the realization of which is just as economical as the usual realization, and even more, if one takes into account the possibility of using a rubber seal 5 of the usual type, one has the advantage of a very long life by absence of deterioration of the seals, and at the same time a great safety while using the entire stroke.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Structural Engineering (AREA)
  • Actuator (AREA)
EP19840114236 1984-11-26 1984-11-26 Hydraulischer Hebebock mit Hubbegrenzung Expired EP0182927B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE8484114236T DE3474134D1 (en) 1984-11-26 1984-11-26 Hydraulic jack with limited travel
EP19840114236 EP0182927B1 (de) 1984-11-26 1984-11-26 Hydraulischer Hebebock mit Hubbegrenzung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19840114236 EP0182927B1 (de) 1984-11-26 1984-11-26 Hydraulischer Hebebock mit Hubbegrenzung

Publications (2)

Publication Number Publication Date
EP0182927A1 true EP0182927A1 (de) 1986-06-04
EP0182927B1 EP0182927B1 (de) 1988-09-21

Family

ID=8192308

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840114236 Expired EP0182927B1 (de) 1984-11-26 1984-11-26 Hydraulischer Hebebock mit Hubbegrenzung

Country Status (2)

Country Link
EP (1) EP0182927B1 (de)
DE (1) DE3474134D1 (de)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1720434A (en) * 1924-12-05 1929-07-09 Oil Jack Inc Fluid-operated jack
US2520426A (en) * 1947-10-15 1950-08-29 Auto Specialties Mfg Co Hydraulic jack
FR998545A (fr) * 1945-10-25 1952-01-21 Perfectionnement aux vérins hydrauliques
FR1175430A (fr) * 1957-02-05 1959-03-26 Saxby Ets Perfectionnements aux transmissions hydro-mécaniques
FR1506058A (fr) * 1965-12-27 1967-12-15 Caterpillar Tractor Co Perfectionnements aux soupapes de dérivation pour vérins hydrauliques
US3404868A (en) * 1966-06-22 1968-10-08 Walker Mfg Co Hydraulic jack
FR2054119A5 (de) * 1969-07-04 1971-04-16 Tangye Shelley Ltd
US3601011A (en) * 1969-07-22 1971-08-24 Tenneco Inc Diffusion ring for limiting hydraulic ram travel
US4077608A (en) * 1977-01-04 1978-03-07 Auto Specialties Manufacturing Company Hydraulic hand jack
FR2547290A1 (fr) * 1983-06-07 1984-12-14 Rassant Sa Ets F Cric hydraulique a limiteur de course perfectionne

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1720434A (en) * 1924-12-05 1929-07-09 Oil Jack Inc Fluid-operated jack
FR998545A (fr) * 1945-10-25 1952-01-21 Perfectionnement aux vérins hydrauliques
US2520426A (en) * 1947-10-15 1950-08-29 Auto Specialties Mfg Co Hydraulic jack
FR1175430A (fr) * 1957-02-05 1959-03-26 Saxby Ets Perfectionnements aux transmissions hydro-mécaniques
FR1506058A (fr) * 1965-12-27 1967-12-15 Caterpillar Tractor Co Perfectionnements aux soupapes de dérivation pour vérins hydrauliques
US3404868A (en) * 1966-06-22 1968-10-08 Walker Mfg Co Hydraulic jack
FR2054119A5 (de) * 1969-07-04 1971-04-16 Tangye Shelley Ltd
US3601011A (en) * 1969-07-22 1971-08-24 Tenneco Inc Diffusion ring for limiting hydraulic ram travel
US4077608A (en) * 1977-01-04 1978-03-07 Auto Specialties Manufacturing Company Hydraulic hand jack
FR2547290A1 (fr) * 1983-06-07 1984-12-14 Rassant Sa Ets F Cric hydraulique a limiteur de course perfectionne

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
KARL TRUTNOVSKI: "Berührungsdichtungen an ruhenden und bewegten Maschinenteilen"; 2 édition, vol. 17, pages 8-22, Kollmann K. Springer Verlag, Berlin, DE. *

Also Published As

Publication number Publication date
DE3474134D1 (en) 1988-10-27
EP0182927B1 (de) 1988-09-21

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