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EP0068495A1 - Dispositif amortisseur pour un cylindre hydraulique - Google Patents

Dispositif amortisseur pour un cylindre hydraulique Download PDF

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Publication number
EP0068495A1
EP0068495A1 EP82105779A EP82105779A EP0068495A1 EP 0068495 A1 EP0068495 A1 EP 0068495A1 EP 82105779 A EP82105779 A EP 82105779A EP 82105779 A EP82105779 A EP 82105779A EP 0068495 A1 EP0068495 A1 EP 0068495A1
Authority
EP
European Patent Office
Prior art keywords
shock absorbing
peripheral surface
port
absorbing member
back pressure
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
EP82105779A
Other languages
German (de)
English (en)
Other versions
EP0068495B1 (fr
Inventor
Hisayoshi Hashimoto
Masami Ochiai
Morio Tamura
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.)
Hitachi Construction Machinery Co Ltd
Original Assignee
Hitachi Construction Machinery Co Ltd
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
Priority claimed from JP9679081U external-priority patent/JPS584804U/ja
Priority claimed from JP15573681U external-priority patent/JPS5860003U/ja
Priority claimed from JP18784181U external-priority patent/JPS5891004U/ja
Priority claimed from JP3341682U external-priority patent/JPS58135506U/ja
Application filed by Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Publication of EP0068495A1 publication Critical patent/EP0068495A1/fr
Application granted granted Critical
Publication of EP0068495B1 publication Critical patent/EP0068495B1/fr
Expired legal-status Critical Current

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Classifications

    • 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

  • This invention relates to a shock absorbing device for a hydraulic cylinder capable of imparting to a piston the function of absorbing the force of shocks in a plurality of stages at the terminating portion of a stroke of the piston of the hydraulic cylinder.
  • shock absorbing device known in the art is disclosed in Japanese Patent Application Laid-Open No. 35478/72 (corresponding to US Application serial No. 128,822).
  • This shock absorbing device comprises a cylindrical shock absorbing port formed in the end wall of the cylinder housing in a manner to extend axially and communicating at one end with the cylinder chamber and at the other end with a suction and exhaust passageway, and a cylindrical shock absorbing member mounted on the piston and adapted to be inserted in the shock absorbing port at the end of the stroke of the piston to reduce the area of the channel in the shock absorbing port.
  • the device functions such that high resistance is offered to a stream of working fluid discharged, in the terminating stages of the stroke of the piston, from the cylinder chamber through the shock absorbing port by the piston as the shock absorbing member enters the shock absorbing port, to thereby restrict the flow rate of the discharged fluid to impart a shock absorbing function to the piston.
  • the shock absorbing device of the prior art has a shock absorbing characteristic such that the instant the shock absorbing member enters the shock absorbing port, deceleration of very high order would take place in the piston and no great deceleration would occur thereafter. Stated differently, the device would only perform a shock absorbing function or energy absorbing function in a single stage. Thus a very high force of impact would be exerted on the hydraulic cylinder the instant the shock absorbing member enters the shock absorbing port, and a high force of impact would be applied to the end wall of the cylinder housing when the piston impinges thereon when it is brought to a halt.
  • the provision of the axially extending shock absorbing port and the suction and discharge passageway communicating with the end portion of the shock absorbing member in the end wall of the cylinder housing would increase the axial length of the end wall of the cylinder housing.
  • one of the objects of the invention is to provide a shock absorbing device for a hydraulic cylinder which is free from the defects of the shock absorbing device for a hydraulic cylinder of the prior art described in the background of the invention.
  • Another object of the invention is to provide a shock absorbing device for a hydraulic cylinder operative to absorb the energy of inertia of the piston assembly at least in two stages.
  • a shock absorbing device comprising means for defining a shock absorbing hole formed in the end wall and extending axially of the housing., passageway means communicating with the shock absorbing hole, and a shock absorbing member mounted on the piston assembly in a manner to align with the shock absorbing hole and adapted to enter the shock absorbing hole in terminating stages of a stroke of the piston to throttle the flow of fluid in the shock absorbing hole, characterized in that said passageway means comprises a port opening in the shock absorbing hole at its inner peripheral surface defining the hole, said port being located in a position in which the area of its opening is reduced by the shock absorbing member.
  • the hydraulic cylinder comprises a cylinder housing including a cylinder 1 and a head cover 2 and rod cover 3 secured to opposite ends of the cylinder 1.
  • the head cover 2 is formed therein with a shock absorbing hole 4 adapted to receive therein a shock absorbing member subsequently to be described, a port 5 opening in the shock absorbing hole 4 at its side, and a supply and discharge passageway 6 communicating with the port 5.
  • the rod cover 3 is formed therein with a shock absorbing hole 7, a port 8 and a supply and discharge passageway 9.
  • the rod cover 3 guides a rod 10 for sliding movement, and the rod 10 has a piston 11 defining hydraulic chambers A and B in the cylinder 1 in which it is slidably fitted.
  • a nut 12 for securing the piston 11 to the rod 10 and the shock absorbing member 13 are located at an end surface of the piston 11 on the head cover 2 side, and another shock absorbing member 14 is located at an end surface of the piston 11 in contact therewith.
  • the shock absorbing members 13 and 14 may be in the form of shock absorbing plungers formed integrally with the rod 10 or piston 11. Alternatively, shock absorbing rings held by the rod 10 through rubber rings may be used.
  • the shock absorbing hole 4 includes a cylindrical inner peripheral surface 4A at which the port 5 opens in the shock absorbing hole 4.
  • the shock absorbing member 13 is aligned with the shock absorbing hole 4 and has a cylindrical outer peripheral surface 13A of an outer diameter slightly smaller than the diameter of the inner peripheral surface 4A.
  • a minuscule annular gap or throttle passageway C is defined between the inner peripheral surface 4A of the shock absorbing hole 4 and the outer peripheral surface 13A of the shock absorbing member 13.
  • the port 5 is positioned such that, as shown in Fig. 3, it is closed by the outer peripheral surface 13A of the shock absorbing member 13 at the end of a stroke of the piston 11.
  • the shock absorbing hole 7 formed in the rod cover 3 includes a cylindrical inner surface 7A
  • the shock absorbing member 14 includes a cylindrical outer peripheral surface 14A.
  • the outer peripheral surface 14A of the shock absorbing member 14 cooperates with the inner peripheral surface 7A of the shock absorbing hole 7 to define therebetween an annular gap D and closes the port 8.
  • a position represented by Q in Fig. 5 is a position (shown in Fig. 2) in which the forward end of the shock absorbing member 13 is positioned against the port 5.
  • FIG. 5 is a point at which the outer peripheral surface 13A of the shock absorbing member 13 fully closes the port 5 (as shown in Fig. 3) immediately before the piston 11 reaches the end of the stroke. Thereafter the piston assembly reaches the end of the stroke and abuts against the end wall of the cylinder 1, thereby being brought to a halt (as represented by a point T in Fig. 5).
  • shock absorption is performed only by the throttling action of the throttle passageway C.
  • the piston speed is reduced as indicated by a curve PQS.
  • the piston still has high speed when it reaches-the end of its stroke and a high force of impact is produced at the end of its stroke.
  • the gap between the shock absorbing member and the shock absorbing hole or the width of the throttle passageway C is only to reduce the gap between the shock absorbing member and the shock absorbing hole or the width of the throttle passageway C and increase its length. This would entail an increase in the overall length of the cylinder and make it necessary to increase the precision with which machining and assembly of the parts are performed.
  • the shock absorbing device of the prior art incorporating therein the aforesaid improvements has a shock absorbing characteristic such that the speed is reduced abruptly as indicated by a dash-and-dot line PR in Fig. 5.
  • a better shock absorbing characteristic is obtained without requiring to increase the precision of machining and assembling of the parts and to increase the length of the cylinder.
  • the aforesaid description refers to the shock absorbing device mounted on the head cover 2 side.
  • the shock absorbing device mounted on the rod cover 3 side operates in like manner, so that the description thereof shall be omitted.
  • the inner peripheral surface of the shock absorbing hole and the outer peripheral surface of the shock absorbing member are both cylindrical in shape.
  • the invention is not limited to this specific shape and one or both of them may be tapering.
  • the use of a tapering inner peripheral surface and/or an outer peripheral surface causes a reduction in the cross-sectional area of the annular gap C or D defined therebetween as the shock absorbing member progressively enters the shock absorbing hole, thereby increasing the shock absorbing effect.
  • Figs. 6 and 7 show an embodiment distinct from the embodiment shown in Figs. 2 and 3.
  • parts similar to those shown in Figs. 2 and 3 are designated by like reference characters and their description is omitted.
  • a shock absorbing hole 21 having a cylindrical inner peripheral surface 21A is formed in the head cover 2, and a port 23 of a suction and discharge passageway 22 opens in the shock absorbing hole 21 at the inner peripheral surface 21A.
  • the shock absorbing member 13 has a cylindrical outer peripheral surface 13A cooperating with the inner peripheral surface 21A of the shock absorbing hole 21 to define therebetween an annular throttle passageway C and operating to close the port 23.
  • the shock absorbing hole 21 extends farther than the port 23 to form a back pressure chamber 24, and the shock absorbing member 13 is constructed such that, as shown in Fig. 7, the forward end of the cylindrical outer peripheral surface 13A moves past the port 23 to enter the back pressure chamber 24 at the end of a stroke of the piston and cooperates with the inner peripheral surface 21A of the shock absorbing hole 21 to define adjacent and posterior to the port 23 a minuscule annular gap or annular throttle passageway E.
  • the annular throttle passageway E functions such that when the shock absorbing member 13 enters the back pressure chamber 24, the pressure fluid in the latter is restricted in its flow to the port 23 to thereby generate a pressure in the back pressure chamber 24.
  • the shock absorbing member 13 In operation, as the piston 11 progressively moves rightwardly in Fig. 6, the shock absorbing member 13 enters the shock absorbing hole 21. Flow of the pressure fluid from the chamber A to the port 23 is suddenly restricted by the throttle passageway C, to perform shock absorption of the first stage. Further movement of the shock absorbing member 13 into the shock absorbing hole 21 results in gradual reduction in the opening of the port 23 as it is closed by the outer peripheral surface 13A of the shock absorbing member 13, thereby perform shock absorption of the second stage. The shock absorbing member 13 continues its movement into the shock absorbing hole 21 even after the former has fully closed the port 23, to generate a high pressure in the back pressure chamber 24, which offers resistance to the movement of the shock absorbing member 13 into the shock absorbing hole 21.
  • the shock absorbing device of the embodiment in conformity with the invention performs shock absorption in three stages.
  • Figs. 8 and 9 are graphs showing shock absorbing characteristics of the embodiment shown in Figs. 6 and 7 as actually measured.
  • a curve (a) represents a change in piston speed
  • points i, ii, iii and iv indicate positions in which shock absorption is initiated immediately before the shock absorbing member 13 enters the shock absorbing hole 21, the shock absorbing member 31 begins to close the port 23 of the suction and discharge passageway 22, the shock absorbing member 13 has completely closed the port 23 and the piston 11 has reached the end of its stroke, respectively.
  • a curve (2) represents a change in the acceleration of the head cover 2.
  • P l . P 2' P 3 and P 4 represent the internal pressure of the hydraulic chamber B (see Fig.
  • a section i - ii represents a first stage shock absorption in which the internal pressure P 2 of the chamber A gradually rises and offers resistance to the piston 11 while the latter is decelerated by the throttling action of the throttle passageway C.
  • a section ii - iii represents a second stage shock absorption in which in addition to the aforesaid shock absorption, the port 23 of the suction and discharge passageway 22 is gradually throttled and the piston is decelerated.
  • a section iii - iv represents a third stage shock absorption in which, following full closure of the port 23, the back pressure p 3 is proaucea in the nacK pressure cnamber 24 to aece- lerate the piston 11.
  • Fig. 10 is a graph showing the data obtained with the shock absorbing device of the prior art relying on the throttle passageway alone for effecting shock absorption. As shown, a curve (a) represents a change in the speed of the piston, and a curve (b) indicates a change in the acceleration of the head cover 2. In Fig. 10, it will be seen that in the shock absorbing device of the prior art, shock absorption is performed only in one stage and that even at the end of a shock absorbing operation, the piston 11 still has a substantial speed as indicated at a point X.
  • the piston 11 is brought to a halt at the.end of its stroke by impinging on the head cover 2, so that a high force of impact is exerted on the head cover 2 and high acceleration is generated in the head cover 2 as indicated at a point Y.
  • smooth deceleration of the piston 11 can be obtained as shown in Fig. 8 and a good shock absorbing characteristic is exhibited.
  • the change in the acceleration of the head cover 2 is almost nil as indicated by the curve (b), indicating that no high force of impact is exerted thereon.
  • Fig. 11 shows a modification of the shock absorbing device mounted on the rod cover 3 side.
  • the cylindrical outer peripheral surface 14A of a shock absorbing member 14 extends beyond a port 32 opening in a shock absorbing hole 31 at its - - inner peripheral surface 31A into a back pressure chamber 33, to define annular throttle passageways D and F on opposite sides of the port 32.
  • the embodiment shown in Fig. 11 performs shock absorption in three stages.
  • the shock absorbing hole and the shock absorbing member have cylindrical inner and outer peripheral surfaces respectively.
  • the invention is not limited to this form of the shock absorbing hole and member, one or both of the shock absorbing hole and member may be tapering in form.
  • Fig. 12 shows a modification of the embodiment shown in Figs. 6 and 7.
  • This modification has a tapering groove 41 formed in a portion of the cylindrical outer peripheral surface 13A of the shock absorbing member 13 facing the port 23.
  • the tapering groove 41 has a progressively increasing depth in going toward the forward end of the shock absorbing member 13.
  • the tapering groove 41 provides a channel for the pressure fluid to flow to the port 23, thereby avoiding sudden deceleration of the piston.
  • the depth of the tapering groove 41 is reduced as the shock absorbing member 13 enters the shock absorbing hole 21, so that the throttling effect increases and a good deceleration characteristic can be exhibited.
  • the piston moves from its position shown in Fig. 12 leftwardly as pressure fluid is supplied through the supply and discharge passageway, pressure fluid is immediately supplied from the port 23 through the tapering groove 41 to the back pressure chamber 24.
  • the embodiment shown in Fig. 12 is capable of quickly and smoothly effecting movement of the shock absorbing member 13, out of the shock absorbing hole 21.
  • Fig. 13 shows an embodiment which comprises, in addition to the parts of the embodiment shown in Figs. 6 and 7, a first ancillary passageway mounting a check valve 42 allowing pressure fluid to flow from the supply and discharge passageway 22 to the chamber A, and a second ancillary passageway mounting a check valve 43 allowing pressure fluid to flow from the supply and discharge passageway 22 to the back pressure chamber 24.
  • the pressure fluid from the suction and discharge passageway.22 is fed into the chamber A and the back pressure chamber 24 through the check valves 42 and 43 respectively when the pressure fluid is supplied from the supply and discharge passageway 22 and the piston 11 has moved into'an expansion stroke, to thereby enable movement of the shock absorbing member 12 out of the hole 21 to be smoothly effected.
  • Figs. 14 and 15 show a still another embodiment in which a shock absorbing hole 50 is defined by a cylindrical inner peripheral surface 50A and a tapering inner peripheral surface 50B extending beyond the port 23 and a back pressure chamber 51 is defined by a tapering inner peripheral surface 50B.
  • the shock absorbing member 13 has a cylindrical outer peripheral surface 13A of a length Lc substantially equal to the length Lt of a cylindrical inner peripheral surface 50A and a tapering outer peripheral surface 13B at the forward end of the former.
  • the tapering outer peripheral surface 13B operates in such a manner that it enters the back pressure chamber 51 and cooperates with the tapering inner peripheral surface 50B to define between the surfaces 13B and 50B an inclined annular gap or throttle passageway G.
  • the rightward movement of the piston 11 causes the shock absorbing member 13 to enter the shock absorbing hole 50, to allow the throttle passageway G to perform a first stage shock absorption.
  • the first stage shock absorption lasts while the cylindrical outer peripheral surface 13A of the shock absorbing member 13 moves in a stroke covering the distance corresponding to the length Ls of the throttle passageway.
  • the area of the opening of the port 23 is gradually reduced by the cylindrical outer peripheral surface 13A of the shock absorbing member 13, to thereby perform a second stage shock absorption.
  • the tapering outer peripheral portion 13B of the shock absorbing member 13 enters the back pressure chamber 51 as shown in Fig. 15, to cause a back pressure to be generated therein.
  • the pressure fluid in the back pressure chamber 51 flows through the throttle passageway G into the port 23, so that resistance is offered by the passageway G to the flow of the pressure fluid.
  • the shock absorbing action performed by the throttling of the port 23 gradually by the cylindrical outer peripheral portion 13A of the shock absorbing member 13 and the shock absorbing action performed by the back pressure in the back pressure chamber 51 and the throttle passageway G are set in motion simultaneously, to thereby bring about rapid deceleration of the piston 11.
  • the cross-sectional area of the throttle passageway G shows a sudden reduction and the resistance offered to the flow of the pressure fluid therethrough rapidly increases.
  • a positive shock absorbing action can be performed to bring the piston 11 to a halt.
  • the tapering surfaces 13B and 50B defining the throttle passageway G may be parallel to each other or angles of inclination a and ⁇ may be equal to each other as shown in Fig. 14.
  • the angle of inclination S of the shock absorbing hole 50 is preferably greater than the angle of inclination a of the shock absorbing member 13.
  • a thin blade orifice can be formed between the forward end of the tapering outer peripheral surface 13B of the shock absorbing member 13 and the tapering inner peripheral surface 50B of the shock absorbing hole 50, so that it is possible to offer resistance to the pressure fluid flowing through the orifice without the fluid being influenced much by the temperature and viscosity of the fluid.
  • Fig. 16 shows an embodiment in which the same concept as incorporated in the embodiment shown in Figs. 14 and 15 is incorporated in a shock absorbing device mounted on the rod cover side.
  • a tapering inner peripheral surface 60B is formed in a portion of a shock absorbing port 60 extending beyond a port 32.
  • the operation of this embodiment is similar to that of the embodiment shown in Fig. 14, so that detailed description shall be omitted.
  • Figs. 17, 18 and 19 show still another embodiment in which, as in the embodiment shown in Fig. 6, the shock absorbing member 13 has a cylindrical outer peripheral surface 13A and a tapering outer peripheral surface 13B, while a shock absorbing hole 70 has a cylindrical inner peripheral surface 70A and a port 23 opening in the hole 70 at the cylindrical inner peripheral surface 70A.
  • the shock absorbing hole 70 is additionally formed with an annular stepped portion 70 C disposed beyond the inner peripheral surface 70A between it and an inner peripheral surface 70B of smaller diameter than the inner peripheral surface 70A, as distinct from the shock absorbing hole 21 shown in Fig. 6.
  • the stepped portion 70C is located in a position spaced apart from the entrance of the shock absorbing hole 70 a distance corresponding to the length Lc of the cylindrical portion of the shock absorbing member 13.
  • a throttle passageway C is defined between the cylindrical outer peripheral surface 13A and the inner peripheral surface 70A of the shock absorbing hole 70, so that the throttle passageway C performs a first stage shock absorption.
  • This shock absorbing action lasts while the cylindrical outer peripheral surface 13A moves a distance corresponding to the length Ls of the throttle passageway C.
  • Further movement of the shock absorbing member 13 causes the cylindrical outer peripheral portion 13A to gradually close the opening of the port 23, to additionally perform a shock absorbing action by the throttling of the flow of the pressure fluid through the port 23, to thereby perform a second stage shock absorption.
  • the back pressure in the back pressure chamber 71 rises because the latter is brought to a closed condition, to thereby offer increased resistance to the shock absorbing member 13.
  • the resistance offered to the flow of the pressure fluid from the back pressure chamber 71 to the throttle passageway E through the orifice H performs a shock absorbing action, thereby enabling a fourth stage or last stage shock absorption to be performed.
  • Fig. 20 shows the results of actual measurements of a change in the speed of the piston and a change in the acceleration of the head cover done in the embodiment shown in Figs. 17-19.
  • a curve (a) represents the speed of the piston
  • a curve (b) indicates the acceleration of the head cover.
  • Fig. 21 shows an embodiment of this concept in the shock absorbing device mounted on the rod cover 3 side, in which a shock absorbing hole 80 has a cylindrical inner peripheral surface 80A of a major diameter, a cylindrical inner peripheral surface 80B of a minor diameter and a stepped portion 80C interposed therebetween.
  • the stepped portion 80C operates in such a manner that a minuscule annular orifice is defined between the tapering outer peripheral surface 14B of the shock absorbing member 14 and the stepped portion 80C.
  • shock absorption is performed in four stages, like the embodiment shown in Figs. 17-19.
  • Figs. 22 and 23 show modifications of the embodiment shown in Fig. 17. Like the embodiment shown in Fig. 12, the modification shown in Fig. 22 is formed with a tapering groove 41 in the shock absorbing member 13. In the modification shown in Fig. 23, check valves 42 and 43 are mounted in first and second ancillary passageways, as in the embodiment shown in Fig. 13. In these modifications of the embodiment shown in Fig. 17, the advantage of being able to readily move the shock absorbing member 13 out of the hold is offered as described by referring to the embodiment shown in Figs. 12 and 13.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Damping Devices (AREA)
EP82105779A 1981-06-30 1982-06-29 Dispositif amortisseur pour un cylindre hydraulique Expired EP0068495B1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
JP9679081U JPS584804U (ja) 1981-06-30 1981-06-30 シリンダ装置
JP96790/81U 1981-06-30
JP155736/81U 1981-10-20
JP15573681U JPS5860003U (ja) 1981-10-20 1981-10-20 シリンダ装置
JP187841/81U 1981-12-16
JP18784181U JPS5891004U (ja) 1981-12-16 1981-12-16 シリンダ装置
JP33416/81U 1982-03-10
JP3341682U JPS58135506U (ja) 1982-03-10 1982-03-10 シリンダ装置

Publications (2)

Publication Number Publication Date
EP0068495A1 true EP0068495A1 (fr) 1983-01-05
EP0068495B1 EP0068495B1 (fr) 1986-03-12

Family

ID=27459785

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82105779A Expired EP0068495B1 (fr) 1981-06-30 1982-06-29 Dispositif amortisseur pour un cylindre hydraulique

Country Status (2)

Country Link
EP (1) EP0068495B1 (fr)
DE (1) DE3269801D1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4807514A (en) * 1987-04-13 1989-02-28 Gratzmueller C A Differential hydraulic jack with damping system for the control of electric circuit-breakers
EP0751315A1 (fr) * 1995-06-27 1997-01-02 KNORR-BREMSE SYSTEME FÜR NUTZFAHRZEUGE GmbH Servo-moteur hydropneumatique, notamment pour véhicules automobiles
EP0734495A4 (fr) * 1994-10-13 1998-10-28 Nigel Eric Rose Moteurs hydrauliques et mecanismes de moteur
EP1677010A1 (fr) * 2005-01-03 2006-07-05 Volvo Construction Equipment Holding Sweden AB Dispositif amortisseur pour un vérin
CN112780633A (zh) * 2021-01-06 2021-05-11 安徽鼎图液压设备有限公司 一种双缸液压油缸

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3323422A (en) * 1965-08-02 1967-06-06 Cessna Aircraft Co Cushion stop for hydraulic cylinders
DE2603041A1 (de) * 1976-01-28 1977-08-04 Licentia Gmbh Elektrischer schalter mit hydraulischem antrieb
US4064788A (en) * 1976-07-29 1977-12-27 Parker-Hannifin Corporation Cushioning means for hydraulic cylinder

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3704650A (en) * 1971-03-29 1972-12-05 Caterpillar Tractor Co Hydraulic jack stroke cushioning means

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3323422A (en) * 1965-08-02 1967-06-06 Cessna Aircraft Co Cushion stop for hydraulic cylinders
DE2603041A1 (de) * 1976-01-28 1977-08-04 Licentia Gmbh Elektrischer schalter mit hydraulischem antrieb
US4064788A (en) * 1976-07-29 1977-12-27 Parker-Hannifin Corporation Cushioning means for hydraulic cylinder

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4807514A (en) * 1987-04-13 1989-02-28 Gratzmueller C A Differential hydraulic jack with damping system for the control of electric circuit-breakers
EP0734495A4 (fr) * 1994-10-13 1998-10-28 Nigel Eric Rose Moteurs hydrauliques et mecanismes de moteur
EP0751315A1 (fr) * 1995-06-27 1997-01-02 KNORR-BREMSE SYSTEME FÜR NUTZFAHRZEUGE GmbH Servo-moteur hydropneumatique, notamment pour véhicules automobiles
EP1677010A1 (fr) * 2005-01-03 2006-07-05 Volvo Construction Equipment Holding Sweden AB Dispositif amortisseur pour un vérin
CN112780633A (zh) * 2021-01-06 2021-05-11 安徽鼎图液压设备有限公司 一种双缸液压油缸

Also Published As

Publication number Publication date
EP0068495B1 (fr) 1986-03-12
DE3269801D1 (en) 1986-04-17

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