GB2164704A - A device for braking the piston of a hydraulic jack at the end of its stroke, in particular a jack for effecting the opening and closing of gates, doors or the like - Google Patents

A device for braking the piston of a hydraulic jack at the end of its stroke, in particular a jack for effecting the opening and closing of gates, doors or the like Download PDF

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Publication number
GB2164704A
GB2164704A GB08520772A GB8520772A GB2164704A GB 2164704 A GB2164704 A GB 2164704A GB 08520772 A GB08520772 A GB 08520772A GB 8520772 A GB8520772 A GB 8520772A GB 2164704 A GB2164704 A GB 2164704A
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United Kingdom
Prior art keywords
piston
closing
conduit
stroke
discharge
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
GB08520772A
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GB8520772D0 (en
GB2164704B (en
Inventor
Luigi Fadini
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.)
Fadini Meccanica
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Fadini Meccanica
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 Fadini Meccanica filed Critical Fadini Meccanica
Publication of GB8520772D0 publication Critical patent/GB8520772D0/en
Publication of GB2164704A publication Critical patent/GB2164704A/en
Application granted granted Critical
Publication of GB2164704B publication Critical patent/GB2164704B/en
Expired legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20Other details, e.g. assembly with regulating devices
    • F15B15/22Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • F15B15/225Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke with valve stems operated by contact with the piston end face or with the cylinder wall
    • EFIXED CONSTRUCTIONS
    • E05LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05FDEVICES FOR MOVING WINGS INTO OPEN OR CLOSED POSITION; CHECKS FOR WINGS; WING FITTINGS NOT OTHERWISE PROVIDED FOR, CONCERNED WITH THE FUNCTIONING OF THE WING
    • E05F15/00Power-operated mechanisms for wings
    • E05F15/50Power-operated mechanisms for wings using fluid-pressure actuators
    • EFIXED CONSTRUCTIONS
    • E05LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES E05D AND E05F, RELATING TO CONSTRUCTION ELEMENTS, ELECTRIC CONTROL, POWER SUPPLY, POWER SIGNAL OR TRANSMISSION, USER INTERFACES, MOUNTING OR COUPLING, DETAILS, ACCESSORIES, AUXILIARY OPERATIONS NOT OTHERWISE PROVIDED FOR, APPLICATION THEREOF
    • E05Y2900/00Application of doors, windows, wings or fittings thereof
    • E05Y2900/10Application of doors, windows, wings or fittings thereof for buildings or parts thereof
    • E05Y2900/13Type of wing
    • E05Y2900/132Doors

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)
  • Power-Operated Mechanisms For Wings (AREA)
  • Closing And Opening Devices For Wings, And Checks For Wings (AREA)

Abstract

In a hydraulic jack for actuating gates, doors or the like there are provided levers 18, 19 and 21, 22 that are moved by the piston 3, 2 just before the end of the stroke thereof to close a valve 10, 11 located on the oil discharge conduit 6, 7, forcing the fluid to flow out through a reduced cross-section branch conduit 12, 13, and thus braking the movement of the piston 2, 3. When lever 19 or 22 is moved by the associated piston 3, 2 it releases a ball 11, 10 to close the respective conduit 7, 6. <IMAGE>

Description

SPECIFICATION A device for braking the piston of a hydraulic jack at the end of its stroke, in particular a jack for effecting the opening and closing of gates, doors or the like The present invention relates to a device for braking the piston of a hydraulic jack at the end of its stroke, particularly of the kind employed to control the opening and closing of doors, gates or the like, and to a jack provided with such a device.
The device is located in the compression chamber inside the jack, and has the function of slowing down the movement of the piston, both when opening and closing, to prevent the same from stopping too suddenly.
There have been known devices for controlling the opening and the closing of doors, gates or the like, wherein the opening and the closing is effected by a hydraulic jack.
One of the several problems to solve in the manufacture of these devices consists in the necessity of slowing down the speed of the jack, and therefore of the gate or door, shortly before the stroke end, so as to prevent a too sudden stopping.
The solutions that have been until now put forward related to gate openers provide with electro-valves that do not allow oil to pass at a predetermined moment; they do not bring about, however, the hoped for results, nor do they provide the reliability and durability characteristics that are required of the apparatus.
More particularly, the solenoids of the electro-valves often burn out, which means dismantling the device: this being usually incorporated in a wall of the housing, it is difficult to reach, and the operation is quite complicated. There is a need for means for gradually slowing the jack piston near the end of its stroke, said means having the same safety and quality characteristics as the other components of the jack.
According to the present invention in one aspect there is provided a device for braking the piston of a hydraulic jack at the end of its stroke, comprising closure means, actuated directly by the piston, for closing the fluid discharge conduit as said piston is near the travel end, there being provided a branch conduit between the cylinder chamber and the discharge conduit downstream of said closure means, the cross-section of said branch conduit being smaller than that of said discharge conduit.
Preferably the closure means consist of a pair of counter-rotating levers that are set by resilient means in a position wherein they engage a closure valve member for the discharge conduit duct and hold it in an open position, said levers being actuated directly by the piston when near the end of its stroke, and being brought to a position wherein they release said valve member to close the discharge conduit.
As will be hereinafter shown, the closure of the main conduit takes place gradually, so that no water hammer occurs inside the circuit.
An embodiment of the invention will now be described, by way of a non-limiting example, with reference to the accompanying drawing in which the single figure shows schematically the section of a gate opener provided with the device according to the invention.
The gate opener comprises a cylinder 1 within which move a pair of opposed pistons 2, 3, connected to each other by a rack 4.
The pistons 2, 3 are operated by fluid supplied by a pump 5 that supplies the fluid under pressure through conduits 6, 7 to the compression chambers 8, 9 that are at the extremities of the cylinder 1.
Neither the hydraulic circuit nor the other illustrated devices connected to the pump 5 will be described, as they are already known.
Between conduits 6, 7 and the respective chambers 8, 9 there is located a corresponding non-return valve 10, 11, of the ball kind.
Chambers 8, 9 are also in communication with respective ducts 6, 7 downstream of the valves 10, 11, through branch conduits 12, 13, whose cross-section is smaller than that of the conduits 6, 7 and flow therethrough can be varied by means of adjustment devices 14, 15 of known type.
The teeth on the rack 4 interact with a toothed wheel 16 keyed on a shaft 17 that actuates the gate or door or the like to be opened and shut. Located inside chamber 9 and hinged thereto is a lever 18, secured to a toothed sector that engages with a similar sector secured in turn to a second lever 19, hinged to the wall of the chamber 9. Accordingly, the rotation of either lever will cause the other lever to rotate in the opposite direction.
A helical spring 20 or the like acts on the lever 18 in a direction urging it to rotate clockwise as viewed in the drawing: therefore levers 18 and 19 usually take on the position in which the valve 11 is wide open as shown in the drawing.
When the lever 19 is moved it interacts with the ball valve 11, so as to create an open passage between chamber 9 and duct 7.
At the opposite side, inside the chamber 8, there is a similar symmetrical device consisting of levers 21, 22 and a spring 23. The working operation takes place as follows: The pump 5 supplies fluid under pressure along conduit 6 to the chamber 8. Due to the oil pressure, the valve 10 is open and pistons 2, 3 are moved to the right as viewed in the drawing. During this movement the rack 4 rotates the toothed wheel 16 and the shaft 17 is caused to rotate. At the beginning of the movement the piston 3 does not contact with lever 18, and the movement may take place freely. At this stage the valve 11 is kept open by the lever 19.
As the piston 3 gets near to the end of its travel, it engages the lever 18 and causes it to rotate anti-clockwise, against the force of the spring 20. The subsequent clockwise rotation of the lever 19 releases the ball of valve 11, which then closes off the conduit 7 through which the oil that was present in chamber 9 is being discharged.
The release of the ball 11 is not sudden but gradual, and the closing of the conduit 7 takes place gradually too, as piston 3 moves forward.
Because of the closure of the conduit 7, the oil now flows out of the chamber 9 through the branch conduit 13 of reduced cross-section, and this brings about the slowing down of the piston in the final phase of its stroke.
The apparatus thus stops, and the position of the lever devices 18. 19 and 21, 22 inside the chambers 8, 9 is reversed, namely levers 21, 22 are in the position in which the valve 10 is open, while levers 18, 19 are in the position in which the valve 11 is shut.
There is thus provided a very effective device that can be conveniently actioned when required, being controlled directly by the pistons.

Claims (8)

1. A device for braking the piston of a hydraulic jack at the end of its stroke, comprising closure means, actuated directly by the piston, for closing the fluid discharge conduit as said piston is near the travel end, there being provided a branch conduit between the cylinder chamber and the discharge conduit downstream of said closure means, the crosssection of said branch conduit being smaller than that of said discharge conduit.
2. A device as claimed in claim 1, in which said closure means for closing the discharge duct is mechanically operated by the piston.
3. A device as claimed in claim 1 or claim 2, in which said closure means consist of a pair of counter-rotating levers that are set by resilient means in a position wherein they engage a closure valve member of the discharge conduit duct and hold it in an open position, said levers being actuated directly by the piston when near the end of its stroke, and being brought to a position wherein they release said valve member to close the discharge conduit.
4. A device for braking the piston of a hydraulic jack substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
5. An actuator for opening and closing gates, doors or the like, provided with braking devices as claimed in any one of the preceding claims.
6. A hydraulic actuator for opening and closing gates, doors or the like, provided with a double action piston, there being provided at both sides of said piston braking devices as claimed in ay one of claims 1 to 4.
7. A hydraulic actuator for the opening and closing of gates or the like, provided with: (a) A pair of pistons movable inside a cylinder and linked to each other by a rack engaging with means for causing the opening and closing of a gate, door or the like; (b) pairs of counter-rotating levers, placed at the extremities of said cylinder, and engageable with closure valves provided on the oil supply and discharge conduits, said levers being directly contacted by their respective piston shortly before it reaches the end of its stroke, in order to enable said valves to be closed; (c) resilient means for urging said levers to a position wherein they keep said valves open; (d) branch conduits for connecting the chamber inside said cylinder with said discharge conduits downstream said valves, the cross-section of said branch conduit being smaller than that of the discharge ducts.
8. A hydraulic actuator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
GB08520772A 1984-09-25 1985-08-20 A device for braking the piston of a hydraulic jack at the end of its stroke, in particular a jack for effecting the opening and closing of gates, doors or the like Expired GB2164704B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT22816/84A IT1220997B (en) 1984-09-25 1984-09-25 DEVICE FOR THE END OF STROKE BRAKE OF HYDRAULIC JACKS, IN PARTICULAR FOR THE OPENING AND CLOSING OF GATES

Publications (3)

Publication Number Publication Date
GB8520772D0 GB8520772D0 (en) 1985-09-25
GB2164704A true GB2164704A (en) 1986-03-26
GB2164704B GB2164704B (en) 1987-12-31

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ID=11200764

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08520772A Expired GB2164704B (en) 1984-09-25 1985-08-20 A device for braking the piston of a hydraulic jack at the end of its stroke, in particular a jack for effecting the opening and closing of gates, doors or the like

Country Status (3)

Country Link
DE (1) DE3533322C2 (en)
GB (1) GB2164704B (en)
IT (1) IT1220997B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2319243A1 (en) * 2006-02-23 2009-05-05 Matz-Erreka, S.Coop Hydraulic actuator for swing gates or overhead doors with pressure switch

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB454861A (en) * 1935-04-06 1936-10-06 Bendix Ltd A new or improved valve for controlling servo-motors
GB584285A (en) * 1944-08-21 1947-01-10 Aircraft Hydraulic Appliances An improved automatic control for hydraulic jacks
GB610945A (en) * 1946-04-12 1948-10-22 Automotive Prod Co Ltd Improvements in or relating to fluid pressure operated jacks
GB1209088A (en) * 1968-04-18 1970-10-14 Massey Ferguson Perkins Ltd Improvements in piston and cylinder assemblies
US3724331A (en) * 1970-03-13 1973-04-03 Toyoda Machine Works Ltd Feed mechanism for machine tool
US3877344A (en) * 1973-03-02 1975-04-15 Allis Chalmers Cushioned hydraulic actuator
GB1520395A (en) * 1976-08-23 1978-08-09 Towmotor Corp Hydraulic jack cushioning apparatus
US4397218A (en) * 1980-12-23 1983-08-09 Allis-Chalmers Corporation Cushion stop for hydraulic cylinder

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2556698A (en) * 1945-02-05 1951-06-12 G F Goodson Piston construction
DE2150828C3 (en) * 1970-10-13 1974-02-14 International Harvester Co., Chicago, Ill. (V.St.A.) Device for influencing the final stroke speed of a piston which is guided displaceably in a cylinder and provided with a damping element

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB454861A (en) * 1935-04-06 1936-10-06 Bendix Ltd A new or improved valve for controlling servo-motors
GB584285A (en) * 1944-08-21 1947-01-10 Aircraft Hydraulic Appliances An improved automatic control for hydraulic jacks
GB610945A (en) * 1946-04-12 1948-10-22 Automotive Prod Co Ltd Improvements in or relating to fluid pressure operated jacks
GB1209088A (en) * 1968-04-18 1970-10-14 Massey Ferguson Perkins Ltd Improvements in piston and cylinder assemblies
US3724331A (en) * 1970-03-13 1973-04-03 Toyoda Machine Works Ltd Feed mechanism for machine tool
US3877344A (en) * 1973-03-02 1975-04-15 Allis Chalmers Cushioned hydraulic actuator
GB1520395A (en) * 1976-08-23 1978-08-09 Towmotor Corp Hydraulic jack cushioning apparatus
US4397218A (en) * 1980-12-23 1983-08-09 Allis-Chalmers Corporation Cushion stop for hydraulic cylinder

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2319243A1 (en) * 2006-02-23 2009-05-05 Matz-Erreka, S.Coop Hydraulic actuator for swing gates or overhead doors with pressure switch

Also Published As

Publication number Publication date
GB8520772D0 (en) 1985-09-25
IT1220997B (en) 1990-06-21
GB2164704B (en) 1987-12-31
DE3533322C2 (en) 1994-11-17
IT8422816A0 (en) 1984-09-25
DE3533322A1 (en) 1986-04-03

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Date Code Title Description
PE20 Patent expired after termination of 20 years

Effective date: 20050819