EP1897845A1 - Sealed hydraulic lifting cylinder with internal oil recovery - Google Patents

Sealed hydraulic lifting cylinder with internal oil recovery Download PDF

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Publication number
EP1897845A1
EP1897845A1 EP07012567A EP07012567A EP1897845A1 EP 1897845 A1 EP1897845 A1 EP 1897845A1 EP 07012567 A EP07012567 A EP 07012567A EP 07012567 A EP07012567 A EP 07012567A EP 1897845 A1 EP1897845 A1 EP 1897845A1
Authority
EP
European Patent Office
Prior art keywords
rod
cylinder
lifting cylinder
chamber
cavity
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Withdrawn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
EP07012567A
Other languages
German (de)
English (en)
French (fr)
Inventor
Luciano Mondani
Diego Colombi
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.)
Lift Tek Elecar SpA
Original Assignee
Lift Tek Elecar SpA
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 Lift Tek Elecar SpA filed Critical Lift Tek Elecar SpA
Publication of EP1897845A1 publication Critical patent/EP1897845A1/en
Withdrawn legal-status Critical Current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
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems
    • 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
    • F15B15/1457—Piston rods
    • 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
    • F15B15/149—Fluid interconnections, e.g. fluid connectors, passages

Definitions

  • This invention relates to a sealed hydraulic lifting cylinder with internal oil recovery, in particular a hydraulic lifting cylinder designed for the masts of fork-lift trucks.
  • this invention relates to a hydraulic lifting cylinder which possesses the advantages of both the above-mentioned solutions: it does not have an external drainage system, is smaller than the immersion type (thrust diameter being equal), and does not have a bleed screw.
  • the cylinder according to the invention has a braking system which acts on the last sector of the rod stroke.
  • a braking system which acts on the last sector of the rod stroke.
  • hydraulic lifting cylinders are currently divided into two types: “immersion” cylinders and “sealed” cylinders.
  • the former have the seal on the rod only, and consequently do not present the problem of draining the oil that accumulates in the cylinder casing.
  • the second ("sealed" ) type of cylinder has the seal on the piston at the base of the rod.
  • a further advantage of the sealed system over the immersion system is that the counterthrust effect does not arise, so the entire operating area of the piston can be exploited, with the result that smaller devices can be made with the same thrust diameter.
  • the drainage pipes that connect the chamber between the cylinder and the rod with the external environment allow a certain quantity of damp air to enter the cylinder, and with time, this can lead to rusting of the inner wall of the cylinder.
  • the present invention offers an improved hydraulic lifting cylinder of the sealed type, characterised in that it has no external oil drainage system, which is replaced by a different recovery system, and that the rod braking device operates in the last sector of the rod stroke, in both the extended and the retracted positions.
  • the improved hydraulic lifting cylinder comprises a cylinder assembly 1 and a rod 2 mounted on a piston 4 designed to run inside it.
  • Cylinder 1 comprises a cylindrical casing 3 closed at either end by a base 5 secured to the ends, and by a cap 6.
  • Base 5 which is secured to one end of the casing, is designed to allow the entry of oil into the cylinder through a duct 7 (in the axial position, as shown in the figure, or the radial position); the inner surface of said base has a projecting shank 8, also hollow, which places the oil inlet in communication with the rear chamber of the cylinder.
  • Cap 6 substantially consists of a hollow cylinder in which rod 2 slides; gaskets 9 and 10 are housed on the inner surface of said cap.
  • Rod 2 consists of a cylindrical rod characterised in that unlike the devices according to the prior art it is not completely solid, but axially perforated for a portion of its length.
  • Said perforation constitutes a cavity in the rod, shown in the figure as 11.
  • Rod 2 is mounted on a piston 4 which slides in the cylinder, allowing the extension and retraction of the rod.
  • the first section of said piston has an outer diameter equal to the inner diameter of the cylinder, while the remainder has a smaller diameter.
  • a seating 12 in the first part houses a gasket 13 between the piston and the cylinder; the second part is externally threaded and screws onto rod 2.
  • the interior of the piston contains a duct 14 which has two sections of different diameters.
  • a one-way valve 16 fitted at the point where the diameter changes, allows the fluid to flow in one direction only.
  • the device operates as follows.
  • sealed cylinders present the problem that the small amount of oil which seeps from the gasket accumulates in the casing between the cylinder and the rod, and must be drained off.
  • This invention eliminates the problem of installing a drainage system by using the innovative system described below.
  • the pressurised oil is then forced to flow through a hole 17 in the wall of the rod, which faces a corresponding channel 18 in the piston.
  • Said channel allows the oil to flow from the chamber between the rod and the cylinder into cavity 11 in the rod.
  • the inner pressure increases and, when it reaches a pre-set value, causes the opening of one-way valve 16, which discharges the oil through piston duct 14 and subsequently into duct 7, through which it is expelled from the cylinder.
  • the improved hydraulic lifting cylinder comprises a cylinder assembly 19, a rod 20 and a piston 21.
  • Cylinder 19 consists of a cylindrical casing 22, closed at either end by a base 23 and a cap 24.
  • Base 23 which, as in the preceding embodiment, is secured to one end of the casing, contains a duct 25 through which oil enters the cylinder.
  • Cap 24 consists of a hollow cylinder inside which rod 20 slides.
  • Gaskets 26 and 27 are housed on the inner surface of said base.
  • Rod 20 consists of a cylindrical rod which is perforated for part of its length; said perforation forms a cavity inside the rod, shown as 28.
  • Piston 21 has a first section with an outer diameter equal to the inner diameter of the cylinder, which contains a seating 29 designed to house gasket 30; the second section, which has a smaller diameter, is screwed to rod 20.
  • a duct 31 formed in said piston leads on one side into rod cavity 28 and on the other side into the rear chamber of the cylinder.
  • a one-way valve 32 fitted on said duct, near the bottom, allows the fluid to flow in only one direction.
  • a tube 33 which acts as an extension for duct 31, is also fitted to duct 31 near the outlet towards rod cavity 28.
  • the device operates as follows.
  • the piston begins to rise, compressing the oil which has leaked into the chamber between the cylinder and the rod.
  • the damping effect created by this hydraulic constriction brakes the ascent of the rod in the last sector of its stroke, preventing it from colliding with cap 24.
  • the leaked oil which has accumulated in cavity 28 is expelled through one-way valve 32, which opens when the pre-set pressure value is reached in the cavity.
  • tube 33 ensures that not all the oil in cavity 28 is expelled through the valve, and that a minimum quantity remains to guarantee the operation of the braking system.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Fluid-Damping Devices (AREA)
  • Actuator (AREA)
EP07012567A 2006-09-06 2007-06-27 Sealed hydraulic lifting cylinder with internal oil recovery Withdrawn EP1897845A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITPC20060036 ITPC20060036A1 (it) 2006-09-06 2006-09-06 Cilindro oleodinamico di sollevamento a tenuta, con recupero interno dell'olio

Publications (1)

Publication Number Publication Date
EP1897845A1 true EP1897845A1 (en) 2008-03-12

Family

ID=38863430

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07012567A Withdrawn EP1897845A1 (en) 2006-09-06 2007-06-27 Sealed hydraulic lifting cylinder with internal oil recovery

Country Status (2)

Country Link
EP (1) EP1897845A1 (it)
IT (1) ITPC20060036A1 (it)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103511389A (zh) * 2013-10-15 2014-01-15 湖南特力液压有限公司 单作用液压缸
CN103939410A (zh) * 2014-03-28 2014-07-23 东北石油大学 液压缸内部液力自密封装置
CN108105198A (zh) * 2016-11-25 2018-06-01 湖北江山液压科技有限公司 一种单作用液压缸
WO2025219942A1 (en) * 2024-04-18 2025-10-23 L.T.E. Lift Truck Equipment S.P.A. Upright of an industrial vehicle

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1990014520A1 (en) * 1989-05-24 1990-11-29 Ab Mecman Piston sealing and dampening device
WO1992008899A1 (en) * 1990-11-09 1992-05-29 Ab Rexroth Mecman Device for stroke end cushioning and speed regulating the movement of a piston in a fluid pressure cylinder
US5960696A (en) * 1996-10-21 1999-10-05 Kayaba Kogyo Kabushiki Kaisha Hydraulic cylinder with press-fitted pipe
EP1197667A2 (en) * 2000-10-10 2002-04-17 Kayaba Kogyo Kabushiki Kaisha Lift cylinder

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1990014520A1 (en) * 1989-05-24 1990-11-29 Ab Mecman Piston sealing and dampening device
WO1992008899A1 (en) * 1990-11-09 1992-05-29 Ab Rexroth Mecman Device for stroke end cushioning and speed regulating the movement of a piston in a fluid pressure cylinder
US5960696A (en) * 1996-10-21 1999-10-05 Kayaba Kogyo Kabushiki Kaisha Hydraulic cylinder with press-fitted pipe
EP1197667A2 (en) * 2000-10-10 2002-04-17 Kayaba Kogyo Kabushiki Kaisha Lift cylinder

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103511389A (zh) * 2013-10-15 2014-01-15 湖南特力液压有限公司 单作用液压缸
CN103511389B (zh) * 2013-10-15 2015-07-15 湖南特力液压有限公司 单作用液压缸
CN103939410A (zh) * 2014-03-28 2014-07-23 东北石油大学 液压缸内部液力自密封装置
CN108105198A (zh) * 2016-11-25 2018-06-01 湖北江山液压科技有限公司 一种单作用液压缸
WO2025219942A1 (en) * 2024-04-18 2025-10-23 L.T.E. Lift Truck Equipment S.P.A. Upright of an industrial vehicle

Also Published As

Publication number Publication date
ITPC20060036A1 (it) 2008-03-07

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