[1]Utn"ted StatesPatent Office 3,3632729 3,363,729 HYDRAULIC BUFFER WITH DISK CONTROL VALVE STRUCTURE Rollin Douglas Rumsey, Buffalo, N.Y., assignor to Houdaille Industries, Inc., Buffalo, N.Y., a corporation of 5 Mich@gan Filed Oct. 23,1965, Ser. No. 503,896 9 Claims. (Cl. 188-96) AB STRACT OF THE DISCLOSURE 10 A hydraulic buffer of the kind having i reservoir about a cylinder communicati@ig through replenishing check valv e means at opposite ends of the working chamber with in which a piston operates in rectilinear buffing com- 1- pres sion and return strokes, has stacked disk vilves in 0 cont rol of buffing displacement of hydraulic fltiid during ope rati6n of the pisto-n. 20 This invention relates to improvemelits in hydraulic buff ers of the recii)r6cal telescopic piston and cylinder type , and more particularly conceriis new and improved valv e structure for cbntrolling displacement of the hydra ulic fluid in the buffing operations of the buffer as- 25 sem bly. Rec :@procal hydraulic buffers are utilized to control rno vement toward o-@ie another of members of apparatus havi ng operational repular or transitory foreefiil movemeii t toward one another which must be at least ippre- 30 ciab ly slowed down, sometimes as a part of the operating cycl e of the apparatus, and often merely to avoid damagin g impact. in some installations buffers are advantageotis baving cont rol valving of the pressure relief type preloaded to 35 yiel d under high velocity impacts at predetermined pressure to afford a high flow volume under a maximum predete rmined pressure force. Ordinary types of relief valves hav e various shortcon-iings. For exaniple, sprina loaded ball valves require excessively large springs and take uP 40 a large amount of space which is generally of an inconveni ent shape for ready incorporation into btiffers. Differenti al area piston types of relief valve do not conveniently fit into buffer geometry. Pilot operated relief valves are too slow in their actioii to be of value. . . 4r> Accordingly, it is an important object of this invention to provide liew and improved control valve - structure esp@-cially adapted for use in buffers and having readily predetermi@iable high pressure resist,,ince values, high flow volume capability c-ombined with rapid response tiriie, simplicity in construction, minimum space require- 60 ments, great durability, substantially failure-proof, unusual reliability, uniform efficiency, and exceptionally low cost. Another object of the invention is to provide a simple 55 pressure relief valve structure capable of operating at very high pressure levels as encountered in, for example, the operation of hydraulic buffers. A further object of the invention is to provide a valve structure of the character described which occupies but 60 a fninimui-n axial space in a hydraulic buffer. A still further object of the invention is to provide a new and improved valve structure of the character indicated, which is operable on a piston, for example, to function in each opp6site reciprocable direction of the 65 piston, without duplication of pirts. Other objects, features and advantages of the present invention will be readily apparent from the - following detailed description of certain preferred embodiinents thereof taken in conjunction with the acconipanying 70 drawing, iii which: FIGURE I is a fragmental loiigitudinal sectional view Patenl,'ed Jan. 16, 196,3 through a hydraulic buffer embodying features of the invention; FIGURE 2 is a fragmentary section,,il detail view takensubstantially on the line II-11 of FIGURE 1; FIGURE 3 is a fragmentary sectio@ial detail view similar to F@IGUR-cl@, 2 but showing a modification; FIGUR@E 4 is a similar fragmentary sectional detail view showing another modification; FIGURE 5 is a fragmentary longitudinal sectional detail view showing a modification in the buffer head control valve; and, FIGURE 6 is a fragmentary longitudinal s--ctional view of the head end portion of a modified buffer construction enibodying features of theitivention. On reference to FIGURE 1, a typical reciprocably operable, telescopic hydraulic buffer 10 embodying features of the invention comprises a tubular housing body 11, having an end closure and head abutment disk member 12 secured in fluid-tight relationship to one end thereof as by means of welding 13. At its opposite end, the tubular body rnember 11 has an external integral annular attachment flange 14 to wbich is attached as by means of bolts 15, a flanged annular closure member 17 which is telescapically fitted into the bore of the body member and carries a leak-preventing annular seal 18. Reciprocalbly guided by the closure flan.-e 17 is a preferably cylindrical piston rod 18 on the inner end portion of which is a piston 19 which desirably comprises a separate nier.,iber secured to the piston rod by meaiis of threads 20 thereon. A rcd seal 21 carried by the bearing elid member 17 prevents extemal leikage along the rod. Btiffing resistance and energy absorption is effected by hydraulic liquid in a cylindrical working chamber 22 defined by a heavy walled tubular cylinder ?.@3 within which the piston 19 is reciprocably operable. An annular seal 24 carried by the piston substantially prevents leakage between the piston perimeter and the cylinder wall. Between the outer perimeter of t e cylinder member 23 and the inner perimeter of the tubular housing 11 is defined a reservoir chan-iber 25. At its front end the cylinder member 23 opposes the end closure member 12. At its rear end, the cylinder member opposes, and is maintained in concentric relation relative to the piston die by a centering boss 27 projecting forwardly and inwardly on the end closure member 17. For purposes of illustration, the piston 19 is shown as at an intermediate position longitudinally within the cylinder charnber 22, btit as installed for se@rvice, the piston may normally be in a retracted or ready position abuttiiig or close to the centering boss 27 under the influence of relurn biasing means 23, scheinatically indicated. Control valves means are provided for hydraulically resisting with predetermined force inward. compression or buffiiig strolces of the piston 19. Desirably, also, return stroke buffing, but of lesser magnitlide of hydraulic resistance is provided for. To this end, at least one of the relatively reciprocably related structures or means, comprisin.- the housin.- and its related structures as the first means and the piston and its related structures as a second n-ieans, carries such control valve, and for practical reasons of efficiency and economy, both of such relatively reciprocal first and second means are equipped with valve strtictiire enibodyirl.@ feattires of the inv,eiition, namely, comprisirg a plurality of circular spring disks each of a predetermined thickness and substantially concentrically as-sombled in a stack with means mounting the stack so that one margin of the stack is seated for normally blocking hydraulic flow but resiliently de@flectable a-,vay from the seat about a fulcrum engaging the opposite side of the stack in radially spaced relation to the seat in response to predeterrnined hydraulic pressure. As exemplified in FIGURE 1, one such control valve 29 is carried in opera-
[2]3,363,729 3 tive association vvith the piston 19 and comprises a st,,ick of individtial slidably related disks 1,0, and a second stich control valve 31 is i-nounted in association with the housinstruciure and comprises a stack of individual slidably related disks 32. In this i-.1sLance, both in-stroke baffing ,tnd retu@rii stroke bufring control are effected by tile valve 29 iil respect to displaceme-@-it of hydraulic fluid throli,-h one or niore axially extendiiig passages 33 tlirou.-h the pistoii 19. For th'@s purpose, the stacked disk valve 29 -s of ainlilar form with its ouer d;arneter sli.-htly less thaii the di-,ir@-icter of the cylindi-ical wal@l of the chaniber 22 and with an inner diame'@er wb;ch will clear the piston rod 18. A combined v-,ilve seat and ftilcrlim tric outer margi,.l of the adjacent face of the stack is p,-ovided bv an an-,ililar r,.dg.-- 34 ari the pisto-,i --@9 ridi@i',Iy olitwarjly abotit the fronc face area of the piston throu-h which the passage 33 opens. ETiga.-in., the inrier margin of the opposile or forward face of the valve stack :is a comb:iiation valve seat and fLilcrLim annular rid.-c 35 provided on a thrust rin.- member ',27 threadedly ciiga.-od onto the inner end portion cf the piston rod 13 to oppose aiid prelo-@id the valve 29. TI-irou.-h this arrii-gemeiit, and during inward buffing stroke of the piston 19, the disks 30 of t@lie valve 29 are adapted to yield resiiiently about the fLilcrLim pro-vided by the rid.-e 34 iii response to predetern-iined pressure a@,,ainst the front face of the valve to opeii or crack away from the ridgc@ 35 servin.as a valve se,,it, in the manner oi' P, relief valve to pass hydraulic fluid from in front of the piston rearwardly throu.-h the passa.-e 33. Overdeflection of the valve disk rearwardly is prevented by a stop surface 33 provided by the front face of 'Lhe piston 19 normally spaced a lir-,iited distance from the inner mar.@in of the valve disk stack. DLiring return strokes of the i3iston, return stroke, bLIffin,- resistance by the valve 29 is effective to a predetermined vallie urtil the disks 30 resilien'Lly deflect away from the rid@-c 34 servii,.g as a valve seat and -,,@oout the fulcri,im provided by tl2e ridge 35 to afford displacement ol' hydratilic iqtiid fro-rii back of the piston forwardly through the passage 33. Over-deffeclion forwardly of the valve disks 30 is avoided by stop stirface 2,9 provided by the thrust ring 37 and normally in '@imited st)-,iced relation forwardly from the forward i-ace of the valve disk staclc. Predetermining the crackin.- press-ure with which the dual direction valve 29 will operate is readily accomplished through several factors, namely, in the btiilt up stiffness of the sprin- itself throti-h selection of the gaii.-e and sprincharacteristics of the spring sheet m@ etal or plate from which the disks 30 are stamped, the sLlf'Lenin@., results of the hardening treatnient to w'ii;ch slibjected, the number of disks einployed in the stack, and the diameter of the disks; the area of the disks between the rid.-es 34 and 35; and in the pre-load pressure settin@ afforded throu.-h the thrust ring 37. It may be observed, that inasmuch as a sn-ialler flow area is presented by the orifice openin.@ at the center of the valve 29, a somewhat greater resislance to op--n@'@n,, of the valve on inward buffer compression stroke oceiirs than during the pullout or return buffer stroke dtirin.which a larger orifice area is atforded about the outer perimeter of the disk stack. In order to assure a substantially uniform annular flow passage about the inner perimeter of the valve 29 past the disks 30, suitable spacer means are provided between the iniier ed.-es of the disks and 'Llie periineter of the piston rod 18, such for example as a convoluted spacer 4-3 (FIGS. 1 and 2). In another form such spacer nicans n-iay comprise axially extending and eircumferentially spaced spacer fingers 41, as shown in FIGURE- 3, which niay be extensioiis frorn eitl-@er the pi@,toji 19 or the tbrlist rin,a 37. If pi-eferred, instead o-f spacer mean@. to provide fi-ee flow P,,issa.-e, one or more @rooves 42 rnay be provided as shown in FIGURE 4, stich as on the order of 4 key way slots extendiii,- only throu-.ho,,it the short distance where passa-eway arour@d the inner ed-es ol. the valve disks 30 il desired. Operation of the control valve 31 as a predetermined hi.-h pressure blow off valve is aq--,eLed by selection of suitable lieavy gauge spring metal sheet stock froin whi--h to produce the valve disks 32, providing the proper riumber of the disks to afford th-, desired resistance to resilient bepdin.- deflection, and affordin- a predetermined effec10 tive pressure area. Iii the illus'rated embodiment, an arran,-4@nieit for pr-- de'crmined valve odening deflection of the valve disk stack at pressures on the ordet of 10,000 to 30,000 p.s.i. comprises four of the disks which are shown as all oithe same gauge which may be varied as 15 to gauge for different predeterniiried pre-load ratings. Sprin.- steel plate is a desirable material since it is easily fabricated by plincliing, turi-iing, heat treatin@ and grinding to close tolerances and high finish. The large nluiiber of disks enables tiie stress level in each disk to be low and 20 Lhe depection of the stack of disks away from the vaive seat to be relltively lar.-e in order to accommodate a large flow rate. Further, action on the valve at its preload is rapid and sn-iooth. In a simple assembly relationship, an annular valve 25 @,-.at 43 is provided for the outer mar-,in of the inrier face of the valve 31 by the head end portion of the cylinder niember 23 which, for this purpose, has an annular inner valve clearance rabbet -roove 44. Engagin.- the opposite face of the valve 31 in predetermined radially inwardly 30 spaced loading relalion to the valve seat 43 iTi an annular fulcrlim rid.-e 45 projecting inwardly on the inner face of the closure head 12. In this instance, for high pressure use, the total thickncss ol. the disk stack of th-- valve 31 is greater than the distance from the seat 43 to the ful35 crun-i 45. To at least some extent, and in add;tion to the valve disk stiff-ni@,ss, prelo-,idi-@ig of the valve is effer-ted by the thrust iinposed by the fulcrum ridge 45 by drawing up on the bolts 15 to draw the head enclosure member 12 toward the valve until either the end n-iember 12 abuts the 40 opposing end of the cylinder metr@ber 23, or a predetermined limit oil draw up is etlec',ed by means of shims (not sho@vn) incerposed between the attachment flan,-e 14 and the flange 17. A dii'lerential area relief valve arran,-ement is attained by the provision of a hole 17 through the disks 32 radially 45 inwardly f.-om flie fulcrum ridge 45 so th,@it the area inside the di-,imeter of the fulcrum ridge 45 is substantially equalized in pressure with the inner face of the valve 31. Hence the operating force against the valve 31 is the 50 differential area between the valve seat 43 and the fule@-um 45 and the area radially inwardly from the fulcrum. Maximum defi'ection of the valve disk 32 and thus a positive liniit upon the maximum stress level that will be encountered in operation, is desirably controlled by a stop surface 48 afforded by the end member 12 opposite 55 the flexing margir, of the valve disk stack. A practical spaced relationship in respect to a valve of about 5 inch diameter has been on the order of between 1/32 and lllr, iveh. This allows a closure veloc-ity on a buffer of this 60 size of about 15 to 25 miles per hour. These characteristics may be changed to accommodate the exact operating reql-iirements, accordin-, to a general formula that the@ higher the velocity at which the buffer must operate, the thinner should be the valve disks 32, and if the forces are 65 high a -reater ntimber of the valve disks shall be supplied. Hydraulic fluid displaced from the working cylinder 22 past the control valve 31 passes from a receiving groove 49 radially outwardly adjacent to the valve seat 43 ar@d 70 one or more communication ports 50 into the reservoir 25. Replen-shing of hydraulic fluid to the area back of the piston 19 is effected through a check valve passage 51 in the end 17 communicating at one end with the reservoir and openin-. at its inner end throu-,h a valve 75 seat 52 controlled by a ball check valve 53 to close the
[3]5 passage durin.- return buffing strokes of the pist6n ihereof. Replenishing fluid flow from the reservoir 25 into the working chamber 22 during return stroke operation of the piston 19 is past a conventional one-way ball check valve 54 in a passage 54a tlirough the front end portion of the cylinder 23. During compression s+rokes of the piston the check valve 54 closes the passage 54a. In the modification of FIGURE 5 an arrangement is depicted in wlaich the effective pressure acting upon the head control valve is the working pressure multiplied by the area betwoen the valve seat and tl-ie fulcrum, inintis twice the area radially inwardly from the fulcrum. To this end, the valve disks are imperforate so that there is no equalization of pressure on the forward face of the valve within the diameter of the fulcrum. This arrangement will provide a higher effective pre-load in relation to the thrust of the fulcrum ridge against the valve disk stack, inasmuch as the hydraulic fluid pressure acting on the valve disk at the center out to the fulcrum ridge acts to close the valve in opposition to the force acting on the valve disks between the fulcrum and the valve seat. Although this arrangement affords higher pre-load to be obtaiiied with lower initial structural loads in the buffer, it does impose higher stresses in the disks and to compensate for this a larger number of disks are employed. Since all of the elements in the embodiment disclosed in FIGURE 5 are substantially identical with the disclosure in FIGURE 1, except for the larger number of valve disks and lack of central pressure equalization, substantial identity is reflected by primed reference numerals and the description in respect to the buffer 10' as to all so-idelitified elements is the sarne as for those elements in FIGURE 1, and those elements not shown may be assumed to be the same as in FIGURE I without the need for repetition. In the embodin-ient of FIGURE 6, a buffer 55 is shown operatin.- on substantially the same principles as the buffer 10 but with a modified head eid structure. Here a tubular housing 57 affords a reservoir 58 about a working cylinder 59 having therein a cylindrical working chamber 60@ Telescopically assel-nbled with the head end portion of the cylinder 59 and retaining it in position is an annular head flange member 61 which beyond the end of the cylinder 59 is of larger outside diameter and engages iii supported relation with the housing member 57 on an axially oriented shoulder 62 maintaining the fla-.ige member in slightly spaced relation to the adjacent end of the cylinder 59. This affords an air bleed passage to the reservoir 58 in cooperation with an air bleed orifice 63 in the normally upper inner margin of the head en-d of the cylinder and in general ali@nment with the split between the ends of a sealing ring 64 of the pist6n ring type affording a high pressure seal betweell the cylinder 59 and the Range member 61. Closing the head end of the, tubular housing 57 is a flanged head cl6sure disk plate member 65 telescoped into the outer end of the housing member with a sealing ring 67 protecting against leakage. Bolts 68 secure the head closure member 65 in place on the housing 57, with shims 69 predetermining the pre-load thrust of an aniiular fulcrum ridge 70 on the inner face of the head closure member 65 against the outer face of a control valve 71 comprising face-to-face substantially equal diameter stacked spring valve disks in mutually -backing free sliding engagement. Normally the outer margin of the inner face of the valve 71 seats substantially sealingly against an annular valve seat 73 provided by the flange member 61 in predetermined radially spaced relation to the fulcrum 70 and on a diameter at least close to the same diameter as that of the working cylinder 60. Opposite the valve seat 73, the end closure member 65 has a deflection limiting stop stirface 74 in predetermined offset relation to the fulcrum ridge 70. I,-or differential area pressure responsivencss of the valve 71, the valve disks 72 have aligned passages 75 therethrough radially inwardly from 87363,729 the fulcrum 70 to equalize pressute on the central area of both sides of the disks. Upbn predetermined pressure blow-off hydraulic fluid displacement past the valve 71 passes from a collection groove 77 through a communication port 78 into the reservoir 53. By virtue of the cylinder retaining and val@,e seat ring flange 61, a check valve by-pass around the valve 71 is enabled. To this end, a lateral passage 79 may be provided through the flange member 61 inwardly from the io valve seat 73 and communicating between the inner perimeter of the flange member and the reservoir 58. Adjacent to its inner end, the passage 79 has a valve seat 80 seating a check valve such as a ball member 81 to close the passage 79 against high pressure hydraulic fluid during 15 compression buffing str6kes of the associated pist6ii (not shown) but enabling repleiiishiiig fluid flow from the reservoir 58 durin@ return strokes of the pisto n. It will be understood that modifications and variations may be effected without departing from the scope of the 20 novel concepts of the present invention. I
