EP0068495B1 - Dämpfungsvorrichtung für einen hydraulischen Zylinder - Google Patents

Dämpfungsvorrichtung für einen hydraulischen Zylinder Download PDF

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Publication number
EP0068495B1
EP0068495B1 EP82105779A EP82105779A EP0068495B1 EP 0068495 B1 EP0068495 B1 EP 0068495B1 EP 82105779 A EP82105779 A EP 82105779A EP 82105779 A EP82105779 A EP 82105779A EP 0068495 B1 EP0068495 B1 EP 0068495B1
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EP
European Patent Office
Prior art keywords
shock absorbing
back pressure
pressure chamber
peripheral surface
port
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.)
Expired
Application number
EP82105779A
Other languages
English (en)
French (fr)
Other versions
EP0068495A1 (de
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/de
Application granted granted Critical
Publication of EP0068495B1 publication Critical patent/EP0068495B1/de
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 at the terminating portion of a stroke of the piston of the hydraulic cylinder.
  • shock absorbing device known in the art is disclosed in US-A-3 704 650.
  • 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.
  • a cushioning means for cushioning the end portion of the stroke of a piston in a hydraulic cylinder comprising a cushioning member, such as a spear projecting axially from the head end of a piston or a sleeve projecting axially from the rod end of the piston and disposed around the piston rod, which, during the cushioned portion of the piston stroke, enters a cylinder head bore to define therewith a restricted passage through which fluid is displaced from the cylinder.
  • the cushioning member When entering the cylinder head bore the cushioning member gradually covers the lateral fluid port opening into the cylinder head bore.
  • An additional damping chamber is provided at the end of the cylinder head bore, which chamber becomes operative when the lateral fluid port is closed by the cushioning member.
  • US-A-4064788 describes a cushioning means comprising a cushioning spear with successively tapered steps having crests made smaller in diameter from one step to the next, the most forward end step being the smallest in diameter.
  • the hydraulic cylinder comprises a cylinder housing including a cylinder 1 and a head cover 2 and rod cover 3 (Fig. 3) secured to opposite ends of the cylinder 1.
  • the head cover 2 is formed therein with a shock absorbing hole 50 adapted to receive therein a shock absorbing member subsequently to be described, a port 23 opening in the shock absorbing hole 50 at its side, and a supply and discharge passageway 22 communicating with the port 23.
  • the rod cover 3 (Fig. 3) is formed therein with a shock absorbing hole 60, a port 32 and a supply and discharge passageway.
  • 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 inner peripheral surface of the shock absorbing hole and the outer peripheral surface of the shock absorbing member are both generally 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 defined therebetween as the shock absorbing member progressively enters the shock absorbing hole, thereby increasing the shock absorbing effect.
  • the 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. 2, 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.
  • 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. 1.
  • the angle of inclination ⁇ 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. 3 shows an embodiment in which the same concept as incorporated in the embodiment shown in Figs. 1 and 2 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. 1, so that detailed description shall be omitted.
  • Figs. 4, 5 and 6 show still another embodiment in which, 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 70C disposed beyond the inner peripheral surface 70A between it and an inner peripheral surface 70B of smaller diameter than the inner peripheral surface 70A.
  • 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 cylin- dricai 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. 7 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. 4 ⁇ 6.
  • a curve (a) represents the speed of the piston
  • a curve (b) indicates the acceleration of the head cover.
  • Figs. 4 ⁇ 6 can, of course, be incorporated in a shock absorbing device mounted on the rod cover 3 side.
  • Fig. 8 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. 4 ⁇ 6.
  • the modification shown in Fig. 9 is formed with a tapering groove 41 in the shock absorbing member 13.
  • check valves 42 and 43 are mounted in first and second ancillary passageways.
  • the pressure fluid from the suction and discharge passageway 22 is fed into the chamber A and the back pressure chamber 71 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 70 to be smoothly effected.
  • 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 70, so that the throttling effect increases and a good deceleration characteristic can be exhibited.
  • pressure fluid is immediately supplied from the port 23 through the tapering groove 41 to the back pressure chamber 71.
  • the embodiment shown in Fig. 9 is capable of quickly and smoothly effecting movement of the shock absorbing member 13, out of the shock absorbing hole 70.

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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)

Claims (5)

1. Hydrualikzylinder, umfassend ein Gehäuse mit einer zylindrischen Seitenwand (1) und wenigstens einer Endwand (2; 3), eine Kolbeneinheit mit einem Kolben (11), der im Gehäuse axialverschiebbar angeordnet ist zum Zusammenwirken mit dem Gehäuse unter Bildung eines Arbeitsraums (A, B) in diesem, und eine Stoßdämpfungsvorrichtung, die aufweist:
ein in der Endwand (2; 3) geformtes und in Axialrichtung des Gehäuses verlaufendes Stoßdämpfungsloch (50; 60), ein Stoßdämpfungsorgan (13; 14), das an der Kolbeneinheit derart angeordnet ist, daß es mit dem Stoßdämpfungsloch (50; 60) fluchtet und in Endphasen des Hubs des Kolbens (11) in das Stoßdämpfungsloch (50; 60) eintritt, um den Fluidstrom aus dem Arbeitsraum (A, B) in das Stoßdämpfungsloch (50; 60) zu drosseln, und einen Zu- und Ablaufdurchlaß (22), der mit dem Stoßdämpfungsloch (50; 60) kommuniziert und eine Öffnung (23, 32) hat, die sich in das Stoßdämpfungsloch (50; 60) an dessen Innenumfangsfläche öffnet, wobei die Öffnung in einer Lage positioniert ist, in der ihr Öffnungsquerschnitt durch das Stoßdämpfungsorgan (13; 14) reduzierbar ist, wobei das Stoßdämpfungsloch eine Rückstaukammer (51) aufweist, die sich über die Öffnung (23; 32) hinauserstreckt, und wobei die Öffnung und die Rückstaukammer so positioniert sind, daß das Stoßdämpfungsorgan in die Rückstaukammer eintritt und dadurch einen Stoßdämpfungsdruck in der Rückstaukammer erzeugt;
dadurch gekennzeichnet, daß die die Rückstaukammer (51) definierende Innenumfangsfläche einen schräg verlaufenden Oberflächenabschnitt (50B, 60B) angrenzend an die Öffnung (23, 32) aufweist und das Stoßdämpfungsorgan (13; 14) einen schrägen äußeren Umfangsflächenabschnitt (13B) hat, der in den schrägen Oberflächenabschnitt eintritt unter Bildung eines sehr kleinen Ringspalts (G) zwischen beiden.
2. Hydraulikzylinder, umfassend ein Gehäuse mit einer zylindrischen .Seitenwand (1) und wenigstens einer Endwand (2; 3), eine Kolbeneinheit mit einem Kolben (11), der im Gehäuse axialverschiebbar angeordnet ist zum Zusammenwirken mit dem Gehäuse unter Bildung eines Arbeitsraums (A, B) in diesem, und eine Stoßdämpfungsvorrichtung, die aufweist:
ein in der Endwand (2; 3) geformtes und in Axialrichtung des Gehäuses verlaufendes Stoßdämpfungsloch (50; 60), ein Stoßdämpfungsorgan (13; 14), das an der Kolbeneinheit derart angeordnet ist, daß es mit dem Stoßdämpfungsloch (50; 60) fluchtet und in Endphasen des Hubs des Kolbens (11) in das Stoßdämpfungsloch (50; 60) eintritt, um den Fluidstrom aus dem Arbeitsraum (A, B) in das Stoßdämpfungsloch (50; 60) zu drosseln, und einen Zu- und Ablaufdurchlaß (22), der mit dem Stoßdämpfungsloch (50; 60) kommuniziert und eine Öffnung (23, 32) hat, die sich in das Stoßdämpfungsloch (50; 60) an dessen Innenumfangsfläche öffnet, wobei die Öffnung in einer Lage positioniert ist, in der ihr Öffnungsquerschnitt durch das Stoßdämpfungsorgan (13; 14) reduzierbar ist, wobei das Stoßdämpfungsloch eine Rückstaukammer (71) aufweist, die sich über die Öffnung (23; 32) hinauserstreckt, und wobei die Öffnung und die Rückstaukammer so positioniert sind, daß das Stoßdämpfungsorgan in die Rückstaukammer eintritt und dadurch einen Stoßdämpfungsdruck in der Rückstaukammer erzeugt;
dadurch gekennzeichnet, daß die die Rückstaukammer (71) definierende Innenumfangsfläche einen zylindrischen Flächenabschnitt (70A, 80A) angrenzend an die Öffnung (23, 32) und einen daran angrenzenden abgestuften Flächenabschnitt (70C, 80C) aufweist, und daß das Stoßdämpfungsorgan (13,14) einen zylindrischen äußeren Umfangsflächenabschnitt (13A, 14A) aufweist, der in den zylindrischen Flächenabschnitt (70A, 80A) eintritt unter Bildung eines sehr kleinen Ringspalts (E) zwischen beiden, sowie einen schrägen Flächenabschnitt (13B), der an den zylindrischen äußeren Umfangsflächenabschnitt (13A, 14A) angrenzt, wobei der schräge Flächenabschnitt (13B) im Zusammenwirken mit dem abgestuften Flächenabschnitt zwischen beiden einen sehr kleinen Spalt (H) am Ende einer Hubbewegung des Stoßdämpfungsorgans begrenzt.
3. Stoßdämpfungsvorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß der schräge äußere Umfangsflächenabschnitt (13B) des Stoßdämpfungsorgans (13) einen Neigungswinkel (a) hat, der kleiner als der Neigungswinkel (ß) des schrägen inneren Umfangsflächenabschnitts (50B) der Rückstaukammer (51) ist.
4. Stoßdämpfungsvorrichtung nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, daß das Stoßdämpfungsorgan (13) an einem der Öffnung (23) zugewandten Teil seiner Außenumfangsfläche mit einer in Axialrichtung des Stoßdämpfungsorgans verlaufenden, sich verjüngenden Nut (41) ausgebildet ist, wobei die sich verjüngende Nut eine Querschnittsfläche hat, die in Richtung zu dem an die Rückstaukammer (51, 71) angrenzenden Ende des Stoßdämpfungsorgans (13) stetig zunimmt.
5. Stoßdämpfungsvorrichtung nach Anspruch 1 oder Anspruch 2, ferner umfassend einen ersten zusätzlichen Durchlaß, der den Durchlaß (22) mit dem Arbeitsraum (A) verbindet und ein Einrichtungsventil (42) enthält, so daß das Fluid aus dem Durchlaß zum Arbeitsraum strömen kann, und einen zweiten zusätzlichen Durchlaß, der den Durchlaß mit der Rückstaukammer (71) verbindet und ein Einrichtungsventil (43) enthält, so daß das Fluid aus dem Durchlaß zur Rückstaukammer strömen kann.
EP82105779A 1981-06-30 1982-06-29 Dämpfungsvorrichtung für einen hydraulischen Zylinder Expired EP0068495B1 (de)

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
JP15573681U JPS5860003U (ja) 1981-10-20 1981-10-20 シリンダ装置
JP155736/81U 1981-10-20
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 EP0068495A1 (de) 1983-01-05
EP0068495B1 true EP0068495B1 (de) 1986-03-12

Family

ID=27459785

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82105779A Expired EP0068495B1 (de) 1981-06-30 1982-06-29 Dämpfungsvorrichtung für einen hydraulischen Zylinder

Country Status (2)

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EP (1) EP0068495B1 (de)
DE (1) DE3269801D1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2613785B1 (fr) * 1987-04-13 1990-11-23 Gratzmuller Claude Verin hydraulique differentiel, avec systeme d'amortissement, pour la commande de disjoncteurs electriques
US5803028A (en) * 1994-10-13 1998-09-08 Rose; Nigel Eric Fluid actuated engines and engine mechanisms
DE19522966A1 (de) * 1995-06-27 1997-01-02 Knorr Bremse Systeme Hydropneumatischer Kupplungskraftverstärker, insbesondere für Kraftfahrzeuge
KR100652872B1 (ko) * 2005-01-03 2006-12-01 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 실린더 쿠션장치
CN112780633B (zh) * 2021-01-06 2023-05-05 安徽鼎图液压设备有限公司 一种双缸液压油缸

Citations (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

Family Cites Families (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

Patent Citations (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

Also Published As

Publication number Publication date
EP0068495A1 (de) 1983-01-05
DE3269801D1 (en) 1986-04-17

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