US3731592A - Valving mechanism for hydraulic storage means, especially for hydraulic testing apparatus - Google Patents

Valving mechanism for hydraulic storage means, especially for hydraulic testing apparatus Download PDF

Info

Publication number
US3731592A
US3731592A US00205957A US3731592DA US3731592A US 3731592 A US3731592 A US 3731592A US 00205957 A US00205957 A US 00205957A US 3731592D A US3731592D A US 3731592DA US 3731592 A US3731592 A US 3731592A
Authority
US
United States
Prior art keywords
piston
cylinder
hydraulic
ports
ring
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 - Lifetime
Application number
US00205957A
Other languages
English (en)
Inventor
H Kreiskorte
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.)
Carl Schenck AG
Original Assignee
Carl Schenck Maschinenfabrik GmbH
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 Carl Schenck Maschinenfabrik GmbH filed Critical Carl Schenck Maschinenfabrik GmbH
Application granted granted Critical
Publication of US3731592A publication Critical patent/US3731592A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
    • G01N3/36—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by pneumatic or hydraulic means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/003—Generation of the force
    • G01N2203/0042—Pneumatic or hydraulic means
    • G01N2203/0048—Hydraulic means

Definitions

  • the present valving mechanism forms part of the load piston cylinder means, for example, of a hydraulic testing apparatus.
  • the load cylinder is provided with a first control inlet at each end thereof and a second control inlet substantially at each end of the resonant stroke of the piston.
  • Storage means are connected to the load cylinder also substantially at each end of said resonant stroke.
  • control ring pistons are slideably arranged on the piston rod on each side of a piston which is fixed to the rod. The control ring pistons close or open the ports to said storage means.
  • the present invention relates to a valving mechanism for hydraulic storage means, especially for hydraulic testing apparatus.
  • Such machines include a first hydraulic piston cylinder arrangement for producing a dynamic, varying load preferably at the resonance frequency of the apparatus or system, and a second piston cylinder arrangement for producing an initial load on which the dynamic varying load is superimposed.
  • the two cylinder piston arrangements may also be operated to produce a testing load conforming to a predetermined load characteristic. The latter mode of operation may also be referred to as a so called slow speed drive.
  • These hydraulic testing machines or systems are adapted for a switch over between the so called resonance operation and the so called slow speed drive as mentioned above.
  • the two hydraulic cylinders are connected to the means which receive or hold the probe which is to be tested mechanically.
  • One of the cylinders produces the dynamically varying load during the so called resonance operation.
  • the other cylinder serves for producing a so called initial load upon which there is superimposed the oscillating load produced by the resonance cylinder. In this manner, for example, it is possible to convert a pure osciilating load into a pulsating load.
  • the piston of the second hydraulic cylinder piston arrangement the so called initial load piston cylinder arrangement
  • the piston of the second hydraulic cylinder piston arrangement is subjected to loads on both of its surfaces and thus it follows the oscillating movements produced by the first or resonant piston cylinder arrangement.
  • the second piston it is necessary that the pressure medium on both sides of the piston in the cylinder is connected to a respective hydraulic storage which is cable of temporarily receiving the displaced volume of pressure medium.
  • the second or initial load piston cylinder arrangement performs another function if, for example, a testing load having a predetermined load characteristic is to be applied to the sample to be tested, however, without a superimposed oscillating load.
  • a testing load having a predetermined load characteristic is to be applied to the sample to be tested, however, without a superimposed oscillating load.
  • the hydraulic storage spaces connected to each side, that is, to the cylinder spaces above and below the second piston would interfere with the desired slow speed drive. Accordingly, it is necessary to close off these storage means for the slow speed drive operation.
  • valves arranged in said conduits whereby the valves must be actuated either by hand or by remote control.
  • Providing additional valves of course increases the costs and besides it requires a separate or additional control step from actuating these valves when the system is to be switched for one type of operation to the other as described above.
  • Anotherdisadvantage of valves in saidconduits is seen in that thevalves act as throttle means in the conduit so that the flow of the pressure medium is dampened as it passes through these valves. Such dampening is particularly disadvantageous because it prevents accomplishing a large resonance rise or at least impedes the attaining of such rise.
  • a valving mechanism which may be automatically operated simultaneously with the switching of a testing apparatus from one mode of operation to another so that no special actuating means are necessary;
  • a valving mechanism for hydraulic storage means especially for hydraulic testing systems, wherein the second cylinder which is connected to said storage means through respective ports in its cylinder wall and wherein a piston rod which has rigidly attached thereto a piston slideable back and forth within said cylinder, is also provided with ring pistons one of which is slideable on said piston rod on each side of said first-mentioned piston.
  • the cylinder is provided with control ports at its ends as well as substantially at .each end of the reciprocating resonance movement of the piston, whereby upon opening of the control ports at the end of the cylinder, the ring pistons are moved to abut against said piston and thereby close said ports to the storage means.
  • the ring pistons are moved away from said first-mentioned piston toward the respective end of the cylinder whereby said ports to the storage means are opened.
  • the ring pistons are provided with sealing means around their circumferential surface. These sealing means are preferably arranged adjacent the end of the respective ring piston which faces away from said first-mentioned piston.
  • FIG. 1 illustrates a schematic diagram of a hydraulic testing machine whereby the hydraulic as well as the electric circuits have been simplified for claritys sake, said machine being capable of producing a dynamic alternating load with an initial load which constitute the testing load and wherein the arrangement is shown in the position for the resonance mode of operation; and
  • FIG. 2 is a diagram similar to that of FIG. 1 but illustrating the arrangement for subjecting the test sample to static loads or to a testing load having a predetermined, slowly varying load characteristic.
  • a sample 1 to be tested for example a tensile rod is secured at one end thereof to a load cell 2 which in turn is secured to the machine frame 3 shown in simplified fashion.
  • the machine frame 3 supports all the members of the hydraulic testing system.
  • the other end of the sample 1 to be tested is secured to a mass 4 which in turn is connected to a piston rod 5.
  • the piston rod 5 has secured thereto a piston 6 which slides up and down or back and forth in a cylinder 7 which constitutes the so called means force cylinder.
  • the just-described piston cylinder arrangement comprising the elements 5, 6, and 7 constitutes the second piston cylinder arrangement of the system.
  • the first piston cylinder arrangement of the system comprises a piston rod 9, a piston 10, and a cylinder 11.
  • the piston rod 9 and the piston rod 5 are connected to each other through an intermediate member 8.
  • the upper end of the piston rod 9 is operatively connected to a movement sensing member 12.
  • a conventional source of hydraulic power (not shown) is connected to the first cylinder 11 through hydraulic conduits 13.
  • the flow of pressure medium through the conduits 13 is controlled by a servo-valve 14 as well as by a hydraulic switching valve 15 in such a manner that the piston 10 is alternately subjected to pressure.
  • first one surface of the piston 10 is subjected to pressure to move the piston 10 and its rod 9 in one direction and then the opposite surface of the piston 10 is subjected to pressure to move it in the opposite direction together with its piston rod and so forth.
  • a sinusoidal, oscillating load is applied to the sample 1 to be tested.
  • the servo-valve 14 is controlled by a central control unit 16 in response to the movement sensor 12 and preferably through an amplifier 17 in such a manner that each of the two hydraulic conduits 13 are alternately connected to the source of hydraulic pressure.
  • the piston 6 which is rigidly secured to its piston rod 5 may be subjected on one of its surfaces by hydraulic fluid either under a predetermined constant pressure or a pressure which varies relatively slowly.
  • the second cylinder is provided with a pair of first control ports 18 located approximately at the points of return of the reciprocating stroke of the piston 6. These control ports 18 are connected to respective hydraulic conduits for the supply and removal of hydraulic liquid.
  • the term reciprocating stroke designates the movement of the piston 6 in response to the resonance movement of the piston 10. Such reciprocating movement must be distinguished from the movement of the piston 6 which the piston 6 performs during the so called slow motion mode of operation.
  • the slow motion movement has a stroke which is substantially longer than said stroke during resonance operation.
  • FIG. 1 depicts said resonant mode of operation.
  • the hydraulic conduits 20 which are connected to the control ports 18 of the cylinder 7 are interconnected with further conduits 21 and through these conduits through respective servovalves 22 and 23 to the source of hydraulic pressure not shown.
  • the servo-valves 22 and 23 are controlled through amplifiers 24 also by the control unit 16 in such a manner that one of the two surfaces of the piston 6 is subjected to the desired pressure.
  • the volume or rather the cylinder volumes adjacent to each side or surface of the piston 6 varies very rapidly with each cycle of oscillation because the piston 6 performs a rapid oscillatory motion in response to the respective oscillatory motion of the piston 10 in the resonance cylinder 11. It is not possible to open and close the hydraulic conduits 20 in an equally rapid manner. Therefore, the volume above the piston 6 and the volume below the piston 6 are connected to respective hydraulic storage means 26.
  • respective hydraulic storage means 26 For this purpose there are provided connecting ports 25 which are located in the wall of the cylinder 7 about at each end of the reciprocatory movement or stroke of the piston 6. In other words, these connecting ports 25 are located at about the return point of said reciprocatory movement of the piston 6.
  • These storage means 26 receive the pressure medium volume which is temporarily displaced due to the oscillatory movements of the piston 6.
  • FIG. 2 is a circuit diagram illustrating the so called slow speed drive.
  • the sample 1 to be tested is to be subjected to static loads or to a slowly varying load or load change.
  • the hydraulic drive for the resonance cylinder 11 has been switched off by means of the switching valve 15.
  • the control or switching valve 19 has been actuated in such a manner that the control ports 27, one of which is provided at each end of the second cylinder 7, are now connected through respective hydraulic conduits 28 to the source of hydraulic pres sure.
  • a ring piston 29 on each side of the piston 6 of the mean load cylinder 7. These ring pistons 29 are slideable back and fourth along the respective portion of the piston rod 6. These ring pistons 29 provide a seal relative to the inner wall of the cylinder 7. Such seal may be even improved by sealing rings 30 to be described in more detail below.
  • the ring pistons 29 are located adjacent to the respective end of the cylinder 7 because the surfaces of the ring pistons 29 which face the piston 6 are subjected to the pressure medium through the control port 18.
  • the pressure medium is admitted through the control openings 27 at the ends of the cylinder 7, the surfaces of the ring pistons 29 which face the respective end of the cylinder 7 are subjected to said pressure medium whereby these ring pistons 29 are pressed against the pistons 6.
  • the ring pistons 29 close the connecting ports 25 to the storage means 26 as well as the control ports 18 which may also be referred to as inlet or outlet control ports.
  • the closing of the connecting ports 25 to the storage means 26 is necessary during the so called slow drive mode of operation in order to avoid that the storage means 26 act as dead space.
  • the switching over from one of the two possible modes of operation such as the resonance mode of operation or the slow drive mode of operation to the other mode of operation is accomplished simply by switching the two control or switching valves and 19.
  • the opening or closing of the respective pressure medium ports in the cylinder 7, especially of the connecting port for the storage means 26 is accomplished automatically by the shifting of the ring pistons 29 in response to the pressure medium.
  • Another advantage of the invention is seen in that during the so called slow drive mode of operation large strokes of the piston 6 are possible without any danger that the control ports 18 and the connecting ports 25 are opened.
  • the control ports 27 which control said slow drive mode of operation are arranged at the ends of the cylinder 7 and because the ring pistons 29 as may be seen from the diagrammatic showing of the drawings, may have a substantial axial height.
  • the invention provides the ring pistons 29 with sealing rings 30 which are arranged preferably at the outer ends of the ring pistons 29 that is, these sealing rings 30 are preferably arranged adjacent to the ring piston end face which faces toward the respective end of the cylinder 7.
  • This position of the sealing rings 30 at the outer ends of the ring pistons 29 has the further advantage that the ring pistons 29 will be positively moved away from the piston 6 upon admission of pressure medium through the ports 18 even if the ports 18, as may be seen in FIG. 2, are not located in a plane defined by the contact between the surfaces of the piston 6 and the ring pistons 29. It will be noted that the ports 18 are located slightly above and below the just-mentioned planes.
  • the arrangement of the ports 18 and 25 approximately at the ends of the point of return of the piston 6, as mentioned above, is determined only by the length of the oscillating stroke during the resonance mode of operation in which situation the ring pistons 29 are located at their respective ends of the cylinder 7. in other words, when the ring pistons 29 are in their end position remote from the piston 6, they must not close the ports 18 and 25.
  • the stroke performed by the piston 6 and thus by the ring pistons 29 during the slow drive mode of operation has no influence on the position of the ports 18 and 25 and, also as mentioned, the stroke during said slow drive mode of operation may be substantially larger than the oscillating stroke during the resonance mode of operation.
  • the pressure storage means 26 may be of conventional structure, for example, these storage means may contain a compressable gas which is separated from the pressure liquid by a membrane.
  • the central control unit 16 receives its input signals from the movement sensor 12 and also from the load cell 2. However, in addition, the central control unit may provide further control signals, for example, so called follow up signals which determine the load characteristic at the hydraulic cylinder 7. Further, the central control unit 16 may have stored therein a complete program for controlling the testing system.
  • a valving mechanism for hydraulic storage means comprising a first hydraulic piston cylinder arrangement including a first cylinder, a first piston rod, a first piston rigidly secured to said first piston rod for sliding in said first cylinder, and control ports in said first cylinder on either side of said first piston, a second piston cylinder arrangement including a second cylinder, a second piston rod, a second piston rigidly secured to said second piston rod for sliding reciprocation in said second cylinder between return points, first control port means at each end of said second cylinder, second control port means in said second cylinder intermediate its ends and about adjacent to said return points of reciprocation of said second piston, third port means in said second cylinder, hydraulic storage means, conduit means for connecting said hydraulic storage means to said third port means, ring piston means slideably located on said second piston rod and on each side of said second piston whereby upon opening of said first control port means the ring piston means are located adjacent to said second piston for closing said third ports to said hydraulic storage means, whereas upon opening of said second control port means the ring piston means are located remote from said
  • each of said ring piston means comprises sealing means around its circumference for providing a seal relative to said second cylinder.
  • each of said ring piston means comprises sealing means around its circumference for providing a seal relative to said cylinder.

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
US00205957A 1971-10-28 1971-12-08 Valving mechanism for hydraulic storage means, especially for hydraulic testing apparatus Expired - Lifetime US3731592A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2153749A DE2153749C2 (de) 1971-10-28 1971-10-28 Absperreinrichtung für hydraulische Speicher bei hydraulischen Prüfmaschinen

Publications (1)

Publication Number Publication Date
US3731592A true US3731592A (en) 1973-05-08

Family

ID=5823645

Family Applications (1)

Application Number Title Priority Date Filing Date
US00205957A Expired - Lifetime US3731592A (en) 1971-10-28 1971-12-08 Valving mechanism for hydraulic storage means, especially for hydraulic testing apparatus

Country Status (2)

Country Link
US (1) US3731592A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE2153749C2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4106586A (en) * 1977-06-06 1978-08-15 Continental Oil Company Hydraulic vibrator
US4630442A (en) * 1984-06-18 1986-12-23 Trol-Mation, Inc. Apparatus and method for pre-filling a hydraulic motor
US5353683A (en) * 1993-07-20 1994-10-11 Snitgen Joseph D Pneumatic transformer
US5435228A (en) * 1993-07-20 1995-07-25 Pneumatic Energy Inc Pneumatic transformer
US20070101562A1 (en) * 2005-10-27 2007-05-10 Gudrun Mikota Apparatus for needling a non-woven material
CN103603842A (zh) * 2013-12-02 2014-02-26 北京乐冶液压气动设备技术有限公司 一种用于振动试验的复合作动缸及其加载方法
EP2746591A1 (en) * 2012-12-21 2014-06-25 Robert Bosch Gmbh Hydraulic drive for fatigue tests, use of a multiple cylinder for fatigue tests and method of controlling the hydraulic drive

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2405105C3 (de) * 1974-02-02 1982-01-21 Carl Schenck Ag, 6100 Darmstadt Verfahren und Vorrichtung zum Absperren von Druckspeichern
DE4015308A1 (de) * 1990-05-12 1991-11-14 Schenck Ag Carl Hydraulischer oszillatorantrieb
JP5821581B2 (ja) * 2011-12-02 2015-11-24 株式会社島津製作所 耐久試験装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415783A (en) * 1944-05-20 1947-02-11 Crane Co Hydraulic operator
US2506374A (en) * 1945-07-02 1950-05-02 Mcmahon Michael Vehicle signal actuating means
US2806449A (en) * 1955-03-03 1957-09-17 Harris Foundry & Machine Co Fluid operated motor
US3312146A (en) * 1964-01-27 1967-04-04 Nord Aviation Fluid pressure jack with three stable positions
DE2023268A1 (de) * 1969-05-14 1970-11-19 L.I.R. S.p.A., Laboratorio Italiano Plcerche, Genua (Italien) iT 13.05.70

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415783A (en) * 1944-05-20 1947-02-11 Crane Co Hydraulic operator
US2506374A (en) * 1945-07-02 1950-05-02 Mcmahon Michael Vehicle signal actuating means
US2806449A (en) * 1955-03-03 1957-09-17 Harris Foundry & Machine Co Fluid operated motor
US3312146A (en) * 1964-01-27 1967-04-04 Nord Aviation Fluid pressure jack with three stable positions
DE2023268A1 (de) * 1969-05-14 1970-11-19 L.I.R. S.p.A., Laboratorio Italiano Plcerche, Genua (Italien) iT 13.05.70

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4106586A (en) * 1977-06-06 1978-08-15 Continental Oil Company Hydraulic vibrator
US4630442A (en) * 1984-06-18 1986-12-23 Trol-Mation, Inc. Apparatus and method for pre-filling a hydraulic motor
US5353683A (en) * 1993-07-20 1994-10-11 Snitgen Joseph D Pneumatic transformer
US5435228A (en) * 1993-07-20 1995-07-25 Pneumatic Energy Inc Pneumatic transformer
US20070101562A1 (en) * 2005-10-27 2007-05-10 Gudrun Mikota Apparatus for needling a non-woven material
US7308744B2 (en) * 2005-10-27 2007-12-18 Neumag Saurer Austria Gmbh Apparatus for needling a non-woven material
EP2746591A1 (en) * 2012-12-21 2014-06-25 Robert Bosch Gmbh Hydraulic drive for fatigue tests, use of a multiple cylinder for fatigue tests and method of controlling the hydraulic drive
CN103603842A (zh) * 2013-12-02 2014-02-26 北京乐冶液压气动设备技术有限公司 一种用于振动试验的复合作动缸及其加载方法
CN103603842B (zh) * 2013-12-02 2015-12-30 北京乐冶液压气动设备技术有限公司 一种用于振动试验的复合作动缸及其加载方法

Also Published As

Publication number Publication date
DE2153749A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1973-04-05
DE2153749B1 (de) 1973-04-05
DE2153749C2 (de) 1973-10-31

Similar Documents

Publication Publication Date Title
US3731592A (en) Valving mechanism for hydraulic storage means, especially for hydraulic testing apparatus
US3575045A (en) A testing machine for applying static and dynamic forces
US3704651A (en) Free piston power source
US5461859A (en) Centering system with one way valve for free piston machine
CN105114502A (zh) 气液阻尼系统
US3610214A (en) Unsymmetrical, double-acting free piston engine
US3892166A (en) Piston and cylinder apparatus arranged for cleaning
US4508015A (en) Hydraulic cylinder
CN103075395A (zh) 基于磁致伸缩驱动电液激振器
US3668974A (en) Reciprocating engine
KR102638478B1 (ko) 왕복동 피스톤 기계로 가스를 팽창시키기 위한 방법 및 장치
JPH06502005A (ja) エンジンまたはコンプレッサの試験方法及び装置
US2924199A (en) Pneumatic servo motor assembly
Reinertz et al. Efficiency Optimized Pneumatic Pressure Booster
US2504945A (en) Apparatus of the reciprocating piston type for delivering fluids
RU2052782C1 (ru) Устройство для контроля герметичности кольцевых уплотнителей гидроцилиндров
CN109141790A (zh) 应用自激振动节能的高压脉冲发生装置
US1845288A (en) Elastic fluid engine
US454590A (en) Air-compressor
Pu et al. Steady state analysis of pneumatic servo drives
SU1608470A1 (ru) Установка дл испытани образцов на прочность при сложном напр женном состо нии
US2819619A (en) Sealed transmission system
JPH05126703A (ja) 試験片を機械的に荷重する試験装置
US783709A (en) Valve mechanism for engines.
CN208546379U (zh) 一种通孔式轻量化液压油缸缸筒