US2893209A - Multi piston ram device - Google Patents

Description

R my /7 3 Sheets-Sheet l y R. H.-co| EY .MULTI PIsToN RAM DEVICE July 7, 1959 Filed March l1, 1955 July 7, 1959 R. H. coLLEY MULT PISTO RAM DEVICE 3 Sheets-Sheet 2 Filed Mach v11, 1955 MWI.

MN @Sw July 'A7,' 1959 R* H, CQLLEY 2,893,209

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MULTI rlsroN RAM DEVICE RowanrHerbei-t Colley, Derby, England, assignor to Rolls-Royce Limited, Derby, England, a British company l Application March 11, 195s, serial No. 493,701

f Claims priority, application Great Britain March 23, 1954 7 claims. `(cl. 60-97) This invention relates to ram devices, such for instance as "rnay be used to adjust area-varying means of variable-area jet nozzles provided at the outlet ends of gas-turbine engineQexLaust pipes. Variable-area jet nozzles are lusually vemployed when reheat combustion Y equipment is provided to burn fuel in the exhaust pipe.

Such jet nozzles usually comprise a vfixed nozzle mem-k berwhich defines Vthe maximum possible effective area'- of the variable-area nozzle and adjustable nozzle elements lwhich are'inoved over the orifice of the iixed nozzle rvmember to give a` reduced eiective area. The adjustable nozzle elements takea number of forms, one well-known y form being theeyelidtype of adjustable element, of which there'are usually two, pivoted substantially about a diamete'r' of the iixed nozzle member, and another form being the linger type, of which'there are usually several, projecting beyond the ixedrnozzle member and pivoted at their upstream ends about axes which are Or'substantially tangential to` the periphery of the fixed Y `'nozzle'.member.-

` jThe' ad'ustable' 'riozzle-'elements are usually actuated f by pneumaticj'ramsisince there is a 4substantial risk vof jjiire if oileoperatedrarns are employed adjacent the hot exhaust pipe;V Withasimple pneumatic ram, it is possible' to obtain only :two positive positionsof adjustment,

L 4'that isf, the kend positions of the' ram piston, ,since huntfingwill 'occurif -th'e piston lis restrained fronrmovement "from an'ntermediate position solely by ibalanceof the lair' pressure loadsv acting on it.

jIt has become desirablevvith modern jet `propulsion zengines fitted with reheat ecjupment, to provide for several different degrees of rehe'at, and for each differentA degree ofreheat `thereisrequired a corresponding nozzle 1 area. 4 v

This''nvention has for an object to provide an im- `p`roved ram device suitable for operating the adjustable nozzle elements of a variable-area nozzle, whereby the piston may be positively positioned, in one sense at least 'of its movement, in more than two positions. The ram device is not', however, ,limited in its use to the operation of'nozzle elements, butinay be employed generally when aram pistonis required Vtd'be stopped between the ends of its ltravel'.

According to the 'present invention, a ram device comnectedftolthe'othe e'nd pistonof said pistons and pro-*i jecting externally of the ram cylinder, each pair of adjabcent pistons havingfcoaxial, nested, telescoping portions comprising an axially extending portion on at least one of thefpair of adjacent pistons, 'a portion having an axial recess on the second piston of the pair, the axially extend- ICC ing portion projecting into the recess, co-operating abutments on said axially extending portion and on the recessed portion respectively limiting relative movement in each direction of the pair of adjacent pistons, and pressure uid supply means selectively connectible to supply pressure fluid to said intermediate spaces and to at least one of the end spaces.'

The other of the end spaces may have pressure air admitted to it either permanently or selectively, or the space may be Vented to atmosphere and the first piston have applied to it a force to urge it in one direction of its travel.

The cylinder will havev as many pressure air supply connections as there are pressure spaces, and it will be appreciated that the spacing of the ports along the cylinder will depend upon the possible relative movement of a piston with respect to its adjacent piston nearer that which has the stops co-operating with the cylinder. In the case of a ram device having more than two pistons one of the pressure air supplies may be eiected centrally, say through the piston rod, and in this way a saving in overall length of the ram device may be obtained.

Two embodiments of ram device according to this invention willvnow be described'with reference to the accompanying drawings in which;v

Figure 1 illustrates a fourpiston ram device,

Figure 2 illustrates a three-piston ram device shown in the end positions of its travel, i

Figures 3 to 6 illustrate four of the intermediate positions obtainable with the ram device of Figure 2, Figure 7 is a diagrammatic viewlof one suitable form of air supply for use with the ram of Figures 2 to A6, and

Figures 8 to 1l show various forms for a part of the ram device shown in Figures 2 tol 6.

Referring now to Figure 1there is illustrated a ram comprising a cylinder 10 and four pistons 50, 51, 52 and 53, of which three pistons, viz: pistons 50, 51 and 52, are similar in construction and in which piston 53 is formed with a piston rod 54 carrying the, fitting 18.

Each of the pistons 50, 51 and 52 is provided with an axial extension 55 to the right which slides on the piston rod 54 and has aange 56 at its right hand end, the flange 56 provides the abutment limitingthe movement of the respective piston and in the case of the piston 56 co-operates with the end of the cylinder or with a circular spring clip 58 mounted in an axial boss 57 on the end of Athe cylinder, and which in the case of the pistons 51 and 52 comesup against the piston next to the right of it in one direction and against a circular spring clip corresponding to the circular spring clip 5S carried in an axial hollow boss on the piston to the right of it.

The piston 53 is limited in its movement relative to the piston 52 by a flange 59 on the rod 54, which flange 59 comes up against the piston 52 in one direction of movement of the piston 5,3 and against a circular spring clip 58 corresponding to the circular spring clips 58 of the other pistons. It will be clear that with this ram device sixteen positions of the iitting 18 relative to the cylinder 10 are obtainable.

From the foregoing description it will be appreciated that the invention provides a simple form of ram device with which more than two positions are obtainable and in which the piston is positively held against movement in one direction.

Referring now to Figure 2, the ram device illustrated comprises three pistons, 60, 61 and 62 of which piston 60 is carried on a piston rod 63 which at its right hand end passes through a seal carried in the cylinder 10 and carries the end fitting 18 and has also a portion 63a extending to the left and entered into a tubular member 65 which carries the piston 61. A circumferentially and radially eX- tending projection 64 is formed at the end of portion 63a Vpiston 60 acting towards the left.

. V3 fari@ .Serves tlimt .tl1...r.rvf-m.11t 0f the piston 6@ relative to the piston 61, the projection 64 co-operating with either the stop at the right hand end of the tubular member 65 provicleckl) a `conical spring retaining ring 66 entered into an annular'groove internally Yof the 'tubular member 65 extended tothe left and enters into a second tubular mem- 1bei' 68 which carries thefthird piston 62. The left hand end ofthe tubularmernber y65 carries'a radially' and` cir-y Y A currifer'elintiallyi extending 'projection 69 which co-operates witheithera second conical spring retaining ring 71 or the yleft hand closed end 70 of the second tubular member 68jfa`nd serves to limit movement of the secondrpis'ton 61 relative to the third piston 62. The second tubular mern ber 68 is also extended to theleftV and carries a radially jand circumferentially"extending projection 72 which limits thertravel of piston'62 in the cylinder by abutting against either the end wall 10 1z of the cylinder or against a third conical spring retainingring73.

,j The .three pistons so, 61 andszaivi-de the cylinder im@ 'two end spaces 74,' and 75 and two intermediate spaces 76 and 77, spaceV 76 being between pistons 60 'and 61 and v spa'ce 77 being between pistons61 and 62. Four ports 78,

79,80 and 81 are provided'onV the cylinder, port 78 communicating with end space 74,` port 79 with' intermediate vspace 76,` port 80 withintermediate space 77 and port 81 withend space 7S. Pressure air is supplied through port 78 permanently to the end space 74 to exert a force on Pressure air is suppliedselectively to the other threespaces 76, 77 and '75 through :the ports 79,580'a'nd 81 bymeians of solenoidcontrolled Valves.

A hole 82 is provided in the tubularmemberGS and a hole 83 is provided in the projection 64 at the end of portion 63al of rod 63 to allow passage of pressure air from port 79vto all partsff space 76. Holes 84 and 85 are provided'in the left-hand vend of tubular member65 and the left-hand end of tubular member 68 respectively, the hole 84 being provided to allow pressure air from port 8 0 togain access to all parts of space 77 "and the hole 85A being provided to allow pressure air from port 81 to gain access to all parts of space 75.

This construction of ram is fully double-acting in all positions, as due to the space 74 beingpermanently supplied with pressure air the piston 60 is biased to move :t'o therleft 'by a forcev equal to the annular area of the piston 60' multiplied bythe air pressure but, dueto the fact thatpressure air supplied to any of the other spaces 76, 77, 75 acts on an area equal to the full area `of the piston, the force tending to move piston 60 to the left will be overcome and there will be a resultant force movingpiston 60 to the right equal to theair pressure multiplied by the cross-sectional area of the piston rod 6 3. Thus if there is no pressure air in the end space l7S and the two intermediate spaces 76, 77 then'the piston 60 will move to the left to the limit of its travel, portion `64abuttin`g against the closed end 67 of the first tubular mem'ber65, portion 69' abutting against the closed end 70 of the Vsecond tubular member 68 and portion 72 abutting against the end 10(1'of the cylinder 10. If 'pressure air is supplied toall the spaces then the ram will vtake up the position shown in the bottompart of Figure 2, portion 64 abutting against therst conical spring retaining ring 66, portion 69 abuttingiagainst the second conical spring retaining ring 71 and portion 72 abutting against the third conical spring retaining ring 73. Figures 3 to 6 illustrate fourvof the intermediate positions 'obtainable with the ram, the position of Figure being 'obtained by supplying pressure air to end yspace 75 and intermediate space'77, `with intermediate space 76 vented to atmosphere, the position ofiFigure 4 being obtained by Venting end space 75 and intermediatespace 77 to atmosphere and supplying pressure air to space 76, the position of FigureS being obtained by supplying pressure air to end space 75 and intermediate space 76 with space 77 vented to atmosphere, and the position of Figure 6 being obtainedhyventing end space 75 to atmosphere and supplying pressure air to both intermediate spaces.

Referring lnow to Figure 7 there isshown one suitable form of air supply means for use with the ram just described.

The control comprises an air. compressor 100 which has a suction pipe 101 connected to any convenient air source, for instance'the ldelivery of a.compressor,of a gas turbine engine with which the ram device is associated, a relief valve 102 connecting the delivery pipe 107 of compressor 100 to one end of a return pipe 103, the other en d of which is connected toi: the suctionpipe 101, air cleaners104, 105 for removing entrained oiland water respectively, `a pressure airreservoir 4106, and a control valve assembly 108 joining `the delivery pipe 107 to branch pipes .r10l9, 110, .111,` 112 leading respectively to ports 78, 79, 80 and 81 of the ram device.

The connection between delivery. pipe 1 07: and branch 109 is a direct connection, but eachofthe other branches 110, 111, 112 has a respective .solenoidfoperated valve 113, which, when the solenoid 11,4.. is rie-energized,V is urged by a spring 115 to close a port 116 to disconnect the branch Yto a vent 117 ,through port .118, and which, when the solenoidr114 is energized, is moved away from port 116 and closes off port. 118. The solenoids 1714 are supplied with operating current from the aircraft battery120 through throttlefcontrolled switches 119.

The parts 66, 71 and 73 whi'ch' form abutments may be rof any convenient form. u of y Referring now to Figure.. 8, .there is illustrated one form which the parts 66, 71 and 73 may take. .The ring is of parallelogram axial section, and. the outer y surface 90a, which is thus frusto-conicahis arranged -to lit againstl the surface 91d of the groove inthey'partzQZ. The inner surface b of the ring ,is likewise frustofconic'al and is parallel to the surface 90a. One end face 90e is contained in a plane at rightanglesto the axis .and seats against the surface 9'1'b. of the `groove in the part 92, and the other end face 90d of the ring isalso contained in a plane at right angles tothe axishfandprojects wholly within the bore ofthe part k.92and forms an abutment surface for engagement by Ethe part 93.to limit the movement of the part 93 relative to the part 92 Jin one direction.` It will be Vseen that in this .case the surface 93a of the part 93 which comes up against the end face 90d is contained in a plane.v at right anglesto the axis, and it will be seen moreoventhat thelabutrnent surface provided by the end .face 90d extends through the full thickness of the ring 90. Alsoit will be seen that axial loads on thering 90 are transmitted to the part 92 over the full radialthickness ofN the ring. l V

Referring now to Figure ,9, there is shown an alternative and preferredl arrangement, and in this c ase the surface 91b of the groove is also frusto-conical `and has its generatrix at right angles to thegeneratrix of 4the surface 91g. The ringr90`in this case is of rectangular section so that the end ,facesv of the ring 90e, 90d are alsofrustoconical. The part 493 is. arranged to bear on the, abutment ring 90 through a surface 9,3b which is also frusto-conical, the part 93 ybeing chamfered to obtain this surface. .KIt will be seen with this arrangement'that the loads on the ringY 90 are purelycompressive loads and that the lines o faction of theuresultan't loads on the end faces 90C, 90d of the ring 90 are the same. This line of action is indicated by a chain line 94.

Referring now to Figure 10, there are indicated a number of other features.

It will be seen that the ring 90 isofsuch axial length that its outer surface 90a has its minimum diameter portion projecting from the groove in the part 92 and that the part 93 has a peripheral rebate 93e adjacent the chamfered surface 93b. The adoption of this feature avoids a diiculty which may otherwise occur when the parts 92 and 93 are relatively movable parts due to peening over of the ring 90 and peening of the outer diameter of the part 93 which may be caused by hammering of the part 93 on the ring 90. By provision of the peripheral rebate 93o any increase in the diameter of the part 93 adjacent the junction between the rebate 93e and the chamfer 93b does not cause an increase in the overall maximum diameter of the part 93 and thus jamming is avoided.

The ring 90 may be removed from its groove in a number of ways. For instance, an annular tool of a section such as is shown at 95 to the left of the ligure may be inserted into the part 92, and in this case the ring is pushed out of the part 92 to the right. Alternatively a number of radial holes 96 may -be provided around the part 92 for the insertion of pins by which the ring 90 may be pushed out of its groove. Alternatively a number of pockets 97, say three, may be provided in the bore of the part 92 to extend into the ring groove and a clawed tool employed to enter the pockets and to pull the ring 90 from the groove by bearing on the surface 90C.

Referring now to Figure 11, there is shown an arrangement in which the stop ring 90 is accommodated in a groove formed externally of the part 93 for abutment by the part 92.

I claim:

1. A ram device comprising a ram cylinder, at least three pistons within the cylinder and dividing the cylinder into two end spaces and a plurality of intermediate spaces, each intermediate space being between an adjacent pair of the pistons, a pair of spaced abutments on the cylinder, one end piston of said pistons co-operating with said pair of abutments whereby travel of the one end piston relative to the cylinder in each direction is limited, a piston rod connected to the other end piston of said pistons and projecting externally of the ram cylinder, each pair of adjacent pistons having coaxial, nested, telescoping portions comprising an axially extending portion on at least one of the pair of adjacent pistons, a portion having an axial recess on the second piston of the pair, the axially extending portion projecting into the recess, co-operating abutments on said axially extending portion and on the recessed portion respectively limiting relative movement in each direction of the pair of adjacent pistons, and pressure fluid supply means selectively connectible to supply pressure uid to said intermediate spaces and to at least one of the end spaces.

2. A ram device as claimed in claim l, having four pistons, whereof three accommodated wholly in the cylinder are hollow and slide in the cylinder between abutments thereon and the others slide in the next adjacent piston between abutments thereon, and whereof the fourth has a piston rod extending outside the cylinder and sliding in one of said three pistons, said rod being connected to a part to be moved by the ram device.

3. A ram device comprising a ram cylinder, first and second end pistons and a third piston between the end pistons, the pistons sliding within the cylinder and divid ing the cylinder into two end spaces and two intermediate pressure spaces, a first hollow piston rod on the first end piston, the hollow piston rod being wholly within the cylinder, co-operating abutment means carried by the hollow piston rod and the cydinder respectively and limiting relative movement of the first end piston within the cylinder, the third piston having an eiective area equal to the eective area of the rst end piston, said rst end piston having a portion with an axial recess therein and the third piston having and axially-extending portion projecting in the recess, co-operating abutments on the recessed portion and the axially-extending portion respectively limiting relative movement of the first end piston and the third piston, a piston rod carried by the second end piston and projecting through the adjacent end space to externally of the cylinder whereby the second end piston has a rst surface of elective area equal to the effective area of each of the other pistons and a second surface facing the adjacent end space of less effective area than the first surface, said third piston having a portion with an axial recess and the second end piston having an axially-extending portion projecting within the recess of said portion of the third piston, co-operating abutments carried by the recessed portion of the third piston and by the axially-extending portion of the second end piston respectively limiting relative movement of the third piston and second end piston, and pressure tluid supply means operable to be connected selectively to the intermediate spaces and at least one of the end spaces.

4. A ram device according to claim 3, wherein the other end space has an outlet connected to atmosphere.

5. A ram device according to claim 3, wherein the other end space has an outlet permanently connected to the pressure fluid supply means.

6. A ram device according to claim 3, wherein the other end space has an outlet selectively connectible to the pressure uid supply means.

7. A ram device as claimed in claim 3, wherein some at least of said abutments for said pistons are provided by rings received in grooves in the cylinder or adjacent pistons, and the pistons are provided with radial projections to co-operate in abutment with the rings.

References Cited in the le of this patent UNITED STATES PATENTS 1,561,341 Martin Nov. 10, 1925 2,005,387 Pelton June 18, 1935 2,229,561 Galanot Jan. 21, 1941 2,667,035 Marsden Jan. 26, 1954 FOREIGN PATENTS 992,586 France July l1, 1951 999,277 France Oct. 3, 1951

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