AU610892B2 - Directing and supporting cylinder for a lemniscate drive means - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE 610 Fom 892 Short Title: Int. Cl: Application Number: Lodged: 'Gnmplete Specification Lodged: Accepted: re Lapsed: Published: 0.a iority: 0 LODGED AT SUB-OFFiCE 2 7 MAY 1988 U Welbourne 0 0 00 00 0 0 0 0 o a 0 0 00 o.

0 0 0 Related Art: 0 0 0 0 TO BE CCPLETED BY APPLICANT Name of Applicant: VOEST-ALPINE AKTIENGESELLSCHAFT dress of Applicant: A-4020 Linz, Turmstrasse 44, Austria.

0 Actual Inventors: WERNER TOFERER and KARL LERCHBAUM Address for Service: CALLINANS, Patent Attorneys, of 48-50 Bridge Road, Richmond 3121, Victoria, Australia.

Cacplete Specification for the invention entitled: DIRECTING AND SUPPORTING CYLINDER FOR A LEMNISCATE DRIVE MEANS The following statement is a full description of this invention, including the best method of performing it known to me:i d

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I I i I I: 1 r SThe invention refers to a FFICR,. P i II zi lenmiscate drive means of a consolidating frame, in which guide rods connected with the floor construction act on a rocker arm articulatedly connected to the cap and at least one guide rod is designed as a ooo, hydraulic cylinder-piston-aggregate.

0 04 F o Description of the Prior Art S The10 From DE-PS 27 29 564 there has already become known coframes, in which was provided a guide rod designed as a hydraulic cylinder-piston-aggregate. The known guide rod 0 0 o0 0o 0 according to thisom DE-PS 27 29 564 there has already become knownder chambers, in which of each both working chambers was slid~bl1 arranged a separate piston comprising a separate o00 piston rod. One of said both piston s c ould be pressed into 00o a the stroke volume with its whole cross-section and thus provide a security means against excessive pressure. The second of these both pistons had to be brought into ts starting position by being completely inserted until engaging the separating wall, so that, for the purpose of being extracted in case of tension stress, the volume of the working chamber had to be compressed via the annular space remaining between the piston rod and the piston. Both working 0 0 S chambers, in which oac ote fr ie others was tn t e separated by a separating wall, sth, fr t p eoing I seodo hs ohpsoshdt ebogtit t lrrt place and. date of Declared at V l enna MIS .SIGN SIGN ppa To: The Commissloer of Patents. (Dr. Vogel (Dr. Eder,) To: The Comi i W 1 -2had to be protected by means of separate excess-pressure valves.

SUMMARY OF THE INVENTION \epnocta ca\ie c -ne The invention now aims at providing ahietig-or inde of the initially mentioned type, in which the same force exerted in case of tension load and pressure load results, without time-consuming adjusting operations, in a response of the excess-pressure valve and a well-defined zero or completely collapsed position can be arrived at in a simple manner.

In accordance with the present invention, therefore, there is provided 0 0 a dirttingantu-bpportingcylinderIfaMa lemniscate guide means of a consolidating frame, including guide rods connected with a floor construction and acting on a rocker arm articulatedly connected to a cap, at least one of said guide rods being s o g Soo. designed as a hydraulic cylinder piston aggregate, wherein two pistons shiftably o0 a arranged on a common piston rod and delimiting a common working chamber are arranged within the cylinder of said hydraulic cylinder-piston-aggregate, said piston rod sealingly extending through said working chamber and said pistons, and o wherein said common piston rod includes stop members for delimiting the shifting S path of said pistons at the side of said pistons located opposite said common working chamber.

On account of two pistons delimiting one common working chamber A being slidably arranged on a common piston rod, this common working chamber can completely be secured by means of only one excessive-pressure valve. For the purpose of adjusting the starting position, it is now sufficient to pressurize the common working chamber and thus to automatically force the pistons into their zero position under the action of pressure. On account of the fact that the piston rod sealingly extends through the working chamber and through the piston and that the piston rod comprises stop members at the side located

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00( 00 o o o 0 00 ooa 0:0 -3opposite the pistons for the purpose of delimiting the shifting path of the pistons, it is achieved that said both pistons are forced one from the other into their zero nr, ,pll1,pp, position when pressurizing the common working chamber. The common working chamber is subjected to pressure in case of tension stress so that only one common excess-pressure valve is sufficient to provide for an exactly defined response of the directing and supporting cylinder to the maximum admissible limiting forces.

In a particularly advantageous manner, the invention is developed such, that the piston cooperating with the free end of the piston rod is kept, with interposition of at least one stop member, at a distance from that front end 0 of the cylinder which is located opposite the piston rod. Also this feature °00 contributes to an exact basic adjustment, in which the hydraulic cylinder-pistonaggregate assumes an expanded length adapted to the existent geometry of the lemniscate guide means. This basic length must, in case of tension load as well as in case of pressure load, provide for a certain amount of stroke-reserve for the expanding movement or retracting movement, so that the desired safety is o4 reliably obtained even in case of forces which act on the cap in a direction deviating from the vertical direction. The lemniscate guide means mainly serves '0 20: the purpose to guide the cap in a vertical direction along an approximately straight path in a direction towards the floor construction. In case of shifting o 004 00 1.

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4 movements of the mine roof, tension forces or compression forces may, in dependence on the direction of the shifting movements, act on the guide rods and might result in an over-load of the links of the guide rods without the provision of such a safety means. The admissible pressure exerted on these links a:id to be limited by the safety valves is dependent on the design of these links and the 600 o. admissible limit pressure is, of course, the same in t-e 00 a a o Cf Sdirection of tension forces and pressure forces of the guide 0 10 rod. Identical adjustment of maximum admissible tension 0 0 00000 Sforces and of maximum admissible pressure forces is, however, 000004 0 a not easily possible with different valves cooperating with different working chambers. The feature of limiting the 0 on 0 o shifting path of the piston cooperating with the free end 0 00 of the piston rod at a distance from that front end of the I' 0 00 o °0 cylinder which is located opposite the piston rod provides the possibility to insert the piston rod, starting from such or 3-o 0o a zero position, for a greater distance into the cylinder, 0 0 4 0o thereby pressing that piston into the common working chamber which is located at a closer distance from the bearing point of the piston rod.

According to a further advantageous development of the device according to the invention, the arrangement is selected such that the piston cocperating with the free end of the piston rod is slidc~kL guided on the piston rod in a sealing manner at an axial distance of its sealing surface S guided within the cylinder and is reduced to a smaller ii1 1 I: 5 diameterkbetween the/sealing surface engaging the cylinder andkthe sealing surface engaging the piston rod. Such an arrangement allows to omit a security means preventing a rotation of the piston, because an annular gap remains between the sealing surfaces,cooperating with the piston rod, of the piston being shiftable on the piston rod, on the one hand, and the wall of the working chamber, on the other hand, said gap remaining also in the case of a completely extended Spiston rod and allowing to expel. from the working chamber 10 the volume of the pressurized fluid being compressed in case o r o 0 0 of tension load.

o000tt In this case, the reduction of the piston rod to a smaller diameter provides on the piston rod an annular 0 00 0 0 a 0 oo shoulder by means of which that piston, which is located o 0 o 0O 00 at a smaller distance from the bearing point of the piston 0 00 rod, can be pressed into the interior of the working chamber in case of pressure load. For the purpose of reliably pro- 0' viding an exact centering effect, that length of the piston rod which is reduced to a smaller diameter shall not be allowed to move out of the cylinder-piston-aggregate and the piston rod shall be guided at its greater diameter when being inserted into the cylinder. In this case, the arrangement is preferably selected such that the piston, which is located adjacent the front surface of the cylinder located opposite the piston rod end, is kept at a distance from the front surface of the cylinder located opposite the end of the piston rod by means ofkstop member thereby making sure i;; -6that the piston rod can not be pulled out of the cylinder- -piston-aggregate with its partial length being stepped down to a smaller diameter.

Complete identity of the response pressures in case of subjecting such a guide rod to tension load and pressure load results from the fact that the pistons pressurize the common working chamber starting from their zero position 000 oo in case of pressure load or of tension load and that the 00 oe ;0 0 o 9 common working chamber is protected by an over-pressure valve.

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000 10 BRIEF DESCRIPTION OF THE' DRAWING o o00 000 In the following, the invention is further explained 0 00000a 0 0 with reference to an example of embodiment shown in the 0 drawings. In the drawings: 0 0 0 0000 Figure 1 shows a.,directing and supporting cylinder 0 0 0 0 00 according to the invention in an axial section and in its '000 oc iO-(VMNo.

0oo 0 zero/position;

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Figure 2 shows a device according to Figure 1 in the 0* completely collapsed condition and 0 040 00 1 Figure 3 shows a device according to Figure 1 in the completely expanded condition.

DETAILED DESCRIPTION OF THE DRAWING In Figure 1, there is shown a cylinder-piston-aggre- 4i gate 1, the cylinder 2 of which may be fixed via a bearing eye 3 on a corresponding linking axis of a, lemniscate drive means. A piston rod 4 is slidc\ 1 guided within the interior of the cylinder 2 and has its bearing eye designated by the ©reference numeral 5. Pistons6 and 7 are shiftably supported |V

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-7on the piston rod 4. The piston 6 is shiftably supported with interposition of sealings 8 along a portion 9 of the piston rod which is reduced to a smaller diameter. The stepped-down portion 9 of the piston rod 4 extends through the piston 6 and has at its free end a nut 10 which serves as a stop member for the piston 6.

The piston 7 located at a closer distance from the 00~ 0 bearing eye 5 is equally slidao supported on the stepped- 010 00D 0 C 0..

0 0 -down portion of the piston rod 4, and sealings 11 are pro- 00 00 0 o10 vided at the sliding support.

o 00 0 0 0 0000 A working chamber 12 remains within the interior of 0 000000 0 0 the cylinder-piston-aggregate and between the pistons 6 and 7, Sboth of these pistons cooperating with this working chamber.

o0 The sealings for providing a seal between the cylinder wall 00 00 15 of the cylinder 2 and the piston 6 are designated by the reference numeral 13, while the corresponding sealings of the piston 7 are designated by the reference numeral 14.

0 The sealing surface of the sealings 13 of the piston 6 00 o oo0 is displaced relative to the radial plane of the piston 6, 0 00 dslcdt ailo and an annular space 15 remains between the sealing surface of the sealing 13 guided within thecylinder and the piston 6, said annular space 15 providing the possibility for the pressurized fluid to flow out of the common working chamber 12 via the connection '16.

In case of pressure load, the piston 7 cooperates with the shoulder 17 of the piston rod 4 and is thus shifted into the working chamber 12. In case of tension load, the piston 0V 0 0; I ^o L S dslce eaie oterailpae ftepitn6 20 ada nua pc 5rmin ewe h eln ufc oftesaig1 uddwti h~yidr n h itn6 Ai' 8 rod 4 drags along with it, on account of the nut 10, the piston 6 together with the sealing surface of the sealing 13 located at an axial distance, noting that the working medium contained within the working chamber 12 is also in this case subjected to the action of pressure.

In Figure 2, the cylinder-piston-aggregate is shown in its completely collapsed position. The piston 7 has been 0000 ooo completely inserted by the shoulder 17 and the piston rod 4, oo0 o 0 noting that this piston has been lifted off of stop members 18 0 0 1 o 10 provided within the interior of the cylinder-piston-aggregate.

Limitation of the completely inserted position is effected oooo€ 0 f via the opposite piston 6 and the sealing surface provided 0 0 with the sealing 13 and located at a distance from this 0 0 0 0 o90 0 0o piston 6, noting that the piston 7 contacts the piston 6.

0 0 0 0 00 The free distance required for this shifting path of the 0 00 0 0 0 a 0 stepped-down portion 9 of the piston rod 4 corresponds to the amount of axial displacement of the 0 0 sealing surface of the sealing 13 relative to the piston 6.

0 00 °o The over-pressure valve connected to the connection 16 and becoming effective in case of pressure stress according to Figure 2 as well as in case of tension stress as illustrated in Figure 3, is designated by the reference numeral 19.

In the representation according to Figure 3, the piston rod 4 has been extended for the maximum length on account of a tension load. Limitation of this shifting movement is again effected via the stop members 18 provided r .0 rV 9 -9within the interior of the cylinder-piston-aggregate, noting that the piston 6 dragged by the nut 10 contacts now the piston 7. In case of tension load, the piston 6 slides along its shifting path,,covered in case of tension load, over the outlet 16 for pressurized fluid, noting that the compressed pressurized fluid can, however, be expelled via the remaining annular space 15 between the sealing surface 13 of the piston 6 within the interior of the wall of the cylinder 2. In this maximum extracted length of the piston a t10 rod 4, the partial area of the piston rod being reduced to o.o a smaller diameter remains within the interior of the 0 0 004 4 q 0 cylinder piston aggregate, so that the area of greater diameter is still guided and centered in the front wall 20 of 0 00 o 0 0 the cylinder piston aggregate.

0 00 0 00 15 One and the same over-pressure valve 19 is thus effective oC0 in case of tension load as well as in case of pressure load of the cylinder piston aggregate 1 and it is possible to o adjust an exactly defined response pressure for both types o oo a "o 0 of load. For the purpose of reliably locating the starting position shown in Figure 1, it is sufficient to pressurize the working chamber 12 via the connection 16 for pressurized fluid, whereby the pistons 6 and 7 automatically assume their defined starting position, starting from which the corresponding safety path is at disposal in case of shifting load and pressure load.

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Claims (4)

1. A lemniscate guide means of a consolidating frame, including guide rods connected with a floor construction and acting on a rocker arm articulatedly connected to a cap, at least one of said guide rods being designed as a hydraulic cylinder-piston-aggregate, wherein two pistons shiftably arranged on a common piston rod and delimiting a common working chamber are arranged within the c. linder of said hydraulic cylinder-piston-aggregate, said piston rod sealingly 0 extending through said working chamber and said pistons, and wherein said o a 9 0 °o common piston rod includes stop members for delimiting the shifting path of said a ooo 10 pistons at the side of said pistons located opposite said common working chamber. 0 0 0 0 0

2. The lemniscate guide means as claimed in claim 1, wherein a first of said pistons cooperating with the free end of said piston rod with inter-position of at least one stop member keeps the second of said pistons at a distance from that 0 "o oo front end of said cylinder which is located opposite said piston rod. O0 04 °o 16'

3. The lemniscate guide means as claimed in claim 2, wherein said first piston o cooperating with the free end of said piston rod is slidably guided on said piston rod in a sealing manner and at an axial distance of its sealing surface guided within and engaging said cylinder and is reduced to a smaller diameter that is between the diameter of the sealing surface engaging said cylinder and that of the sealing surface engaging said piston rod. %F A4/1 I' 11

4. The lemniscate guide means as claimed in any one of claims 1 to 3, wherein the second of said pistons, which is located adjacent the front surface of said cylinder located opposite said piston rod end is kept at a distance from the front surface of said cylinder located opposite said piston rod end by at least one stop member. The lemniscate guide means as claimed in any one of claims 1 to 4, wherein said pistons pressurise said common working chamber starting from their 000 0 400 ,0o zero or starting position as _hprrnhpiTf- defi-n in case of pressure load or go 0 o tension load and wherein said common working chamber is secured by means of 0 00 o0 o o*10 an over-pressure valve. oo o oo 0 6. A lemniscate guide means of a consolidating frame, substantially as described herein with reference to the accompanying drawings. S 7. A consolidating frame including a lemniscate guide means as claimed in 0 0 o" claim 1, substantially as described herein with reference to the accompanying 0 0 15 drawings. 0O 0 0 o 0 00 0 DATED this 4th day of March 1991. VOEST-ALPINE AKTIENGESELLSCHAFT By their Patent Attorneys: CALLINAN LAWRIE