US3218052A

US3218052A - Hydraulic cushion metering pin arrangement

Info

Publication number: US3218052A
Application number: US318384A
Authority: US
Inventors: William H Peterson
Original assignee: Pullman Inc
Current assignee: Pullman Standard Inc; Pullman Inc
Priority date: 1963-10-23
Filing date: 1963-10-23
Publication date: 1965-11-16
Anticipated expiration: 1982-11-16

Description

Nov. 16, 1965 w. H. PETERSON HYDRAULIC CUSHION METERING PIN ARRANGEMENT 4 Sheets-Sheet 1 Filed 001'.. 25, 1963 WW @be NOV- 16, 1955 w. H. PETERSON HYDRAULIC CUSHION METERING PIN ARRANGEMENT 4 Sheets-Sheet 2 INVENTOR. WILUAM H. PETERSON Filed OCT.. 25, 1963 Nov. 16, 1965 w. H. PETERSON HYDRAULIC CUSHION METERING PIN ARRANGEMENT 4 Sheets-Sheet 3 Filed 0G12. 23, 1965 INVENTOR. Wu.\.\AM H. PETERSON Nov. 16, 1965 w. H. PETERSON HYDRAULIC CUSHION METERING PIN ARRANGEMENT Filed our. 2s, 1963 4 Sheets-Sheet 4 INVENTOR 3,218,052 HYERAULIC CUSHIN METERING PIN ARRANGEh/IEN'I Wiliiam H. Peterson, Homewood, Ill., assigner to Pullman Incorporated, Chicago, Ill., a corporation of Delaware Filed Oct. 23, 1963, Ser. No. 3I8,384 1 Claim. (Cl. 267-1) The present invention relates to hydraulic cushion devices and more particularly to an improved cushion device and to a means and method for assembling the cushion device.

The hydraulic cushion device of the present invention is of the general type comprising basically two relatively telescoping members having arranged therebetween the hydraulic fluid which is operative upon the application of an impact force on the members to dissipate a portion of the kinetic energy of the impact force. A cushion device embodying the general principles to which the improvements present invention relate is shown and described in US. patent, No. 3,003,436.

It is a principal object of the present invention to provide a hydraulic cushion device constructed and arranged to prevent fluid leakage during use.

It is a further object to provide an improved hydraulic cushion device having a new and novel metering pin attachment structure which is constructed and arranged to prevent fluid leakage from the device during use.

It is another object to provide an improved hydraulic cushion device wherein the metering pin employed to control the cushioning force of the device is formed with a threaded end which is threadably fastened within a blind opening in the cylinder head of the device and is formed at its other end with an attachment section adapted to receive an assembly tool for threading the metering pin in the blind opening.

It is still another object of the present invention taken in conjunction with the foregoing objects to provide an assembly tool for facilitating the attachment of the metering pin in the device.

It is a further object of the present invention to provide a new and novel method for assembling the cushion device.

In the drawings:

FIG. l is a fragmentary cross sectional view of a cushion device embodying the present invention with the components shown in the normal extended or neutral position.

FIG. 2 is a fragmentary cross sectional view of the cushion device, but showing the components in the contracted position.

FIG. 3 is a fragmentary view of the metering pin employed in the cushion device.

FIG. 4 is an end View of the metering pin taken generally along the lines 4 4 of FIG. 3.

FIG. 5 is a cross sectional View of the metering pin taken generally along the linesjS-S of FIG. 3.

FIG. 6 is a fragmentary exploded view of the assembly tool employed to fasten the metering pin Within the cushion cylinder and showing the attachment projection on the metering pin which is seatable within the socketk of the tool.

FIG. 7 is a fragmentary cross sectional view of a partially assembled cushion device and showing in particular the disposition of the assembly tool therein for securing the metering pin on the cylinder head.

FIG. 8 is an end view of the assembly tool.

FIG. 9 is a cross sectional view taken generally along the lines 9 9 of FIG. 7.

FIG. l0 is an enlarged fragmentary cross sectional View of the assembly tool and the attachment projection of the nited States Patent metering pin taken generally along the lines 10-10 of FIG. 7.

FIG. l1 is a cross sectional View taken generally along the lines 11-11 of FIG. 10.

F IG. ll2 is a cross sectional View taken generally along the lines 12-12 of FIG. 10.

Referring now in particular to FIGS. l and 2, there is shown a cushioning -device 10 embodying the present invention and including generally a cylinder 11 having a lbore 12 charged with a suitable hydraulic fluid; a fluid displacement means 13 telescopingly arranged relative to the cylinder 11 for movement from a normal fully extended or neutral position (FIG. l) to a contracted position (FIG. 2) upon the application of a shock force to the device 10 and ybeing operative during such movement to displace the hydraulic fluid within the bore 12 to dissipate a portion of the kinetic energy of the impact force; a metering pin 14 for controlling the displacement of the fluid within the bore 12 to impart an approximate constant force travel closure characteristic to the device; and a resilient means 16 disposed between the fluid displacement means 13 and the cylinder 12 for returning the components to their fully extended position upon dissipation of the shock force.

The cylinder 11 includes a tubular shell 17 formed preferably from a rigid metallic preformed tube capable of withstanding the internal pressures to which the cylinder is subject during use. The shell 17 may be formed of cold drawn steel tubing of Which the inner Wall is formed with a smooth nish to permit efficient operation of the fluid displacement means 13 therein.

The shell 17 is closed at one end by a cylinder head 18 having a groove 19 formed therein for receiving the end of the shell 17 and the latter is fixed therein as by welding to form a leak proof joint. The cylinder -head 18 which may beV of any suitable contour such as for example, circular or rectilinear, is sized to project outwardly of the outer diameter of the shell to form a retaining ledge against which one end of the resilient means or spring means 16 abuts.

As shown, the other end of the shell 17 is Iformed with a boot chamber bore 21 of larger diameter than the bore 12. Disposed within the boot chamber -bore 21 is an intermediate cylinder head 22 having an axial opening 23. The intermediate cylinder Ihead 22 may be formed at the inner end with an inner section 24 of a diameter substantially equal to the diameter of the boot chamber bore 21, an intermediate section 26 of lesser outer diameter outwardly of the inner section 24, and a `boss 27 on which one end of a flexible boot reservoir 28 is secured as more `fully to be explained hereinafter.

Fixing the intermediate cylinder head 22 within the boot chamber bore 21 is a snap ring 31 which is disposed Within a groove 32 formed in the inner Wall. The snap ring 31 is engageable with a collar 33 threada-bly fastened on the outer end of the intermediate section 26 of the intermediate cylinder head 22 such that the inner section abuts and is held firmly engageable with the shoulder 29.

Slidable on the intermediate section 26 and disposed between the snap ring 31 and the inner section 24 is a ring member 34 and a sealing gasket 36 such as an O ring. A plurality of radially spaced bendable clips 37 compress the O ring 36 between the ring member 34 and the inner section 24 so that a substantially iluid tight seal is formed at the inner wall of the boot chamber bore 21. As shown in the phantom lines in FIG. 1, the bendable clips 37 are initially inserted in bent form between the collar 33 and the slidable ring member 34 and thereafter flatten.

Access to insert the clip members and to straighten the latter is achieved through radially spaced openings 38 formed in the shell 17. Upon straightening of the clips .2% the slidable ring 34 is urged toward the inner section 24E such that the resilient gasket 36 is compressed therebetween and thus causes the latter to radially expand and sealingly engage the inner wall of the boot chamber bore 2l. in this manner a fluid tight seal is formed at the intermediate cylinder head 22.

The fluid displacement means i3 includes a piston rod 39 to one end of which there is fixed a piston head di, which is reciprocable within the cylinder bore it?. between the cylinder head 18 and the intermediate cylinder head 22. Fastened to the other end of the piston rod is a second cylinder head d2.

The piston rod 39 is of tubular construction including a bore i3 and may be formed of a rigid material such as cold drawn steel. Radially spaced ports 44 are formed in the piston rod 39 adjacent to the piston head 4l for providing communication between the piston rod bore and the cylinder bore l2 as more fully to be explained hereinafter.

The piston head il is preferably formed from a metal Y such as steel and comprises a disk like body having a planar forward face d6 and a planar rearward face 47. The planar rearward face 47 merges it into a conical feed surface d8 which terminates in a rim 49 defining the perimeter of an orifice 5l formed axially in the piston head di. The piston head di is formed on its forward face 4d with a recess 52 whichreceives the terminal end of the tubular piston rod 39 and the latter is fixed thereto as by welding.

For guiding the fluid displacement means i3 for relative telescoping movement within the cylinder bore l2 and for forming a seal between the inner wall 53 of the cylinder il and the piston head 4l, the latter is provided with an elevated seal forming and guiding member 54. ln this connection it is mentioned that the cushioning device l@ is primarily intended for use in railway vehicle car structures for providing lading and car body protection. When thus employed, the cushioning device l@ is disposed between the coupler carrying structure and the lading supporting structure to absorb a sufficient portion of the energy of the impact to protect the lading and car body. The structural environment in which the cushion device l@ is employed is such that relative cooking may occur between the cylinder ll and the fluid displacement means i3. This coching condition may result in galling between the metallic surfaces of the piston head and the cylinder wall.

To preclude galling and at the same time form a seal, the member 54 is formed as a split ring made preferably from a laminated phenolic resin. rThe split ring 5d is seated within a peripheral groove 56 formed in the piston head 4I. such that the outer circumference thereof contacts the inner wall 53 above periphery of the metallic piston head dit. The guiding and sealing ring 5d, which is primarily characterized by its non-affinity for the metallic surface and its ability to conform to the contour of the inner wall 53, forms an ecient and effective sealing and guiding means.

The tubular piston rod 39 is of a diameter which defines an annular passage 57 with the axial opening 23 in the intermediate cylinder head 2d and provides communication between the low pressure chamber M7 on one side of the piston head dit and the hexible boot reservoir 2E. rihe flexible boot reservoir or invaginating tube 2S is formed from a fluid impervious flexible material which is capable of resisting the corrosive or deteriorating eects which may be present in the hydraulic fluid employed in the device and advantageously may be a neoprene-burla type of rubber having special additives for low temperature flexibility. The invaginating tube 2d is fixed at one end to the boss 27 of the intermediate cylinder head by means of a hose clamp S8. At its other end, the invaginating tube 28 is reversely bent and the reversely bent end is xed to the tubular piston rod 39 also by means of a hose clamp 53. To firmly grip the ends of the invaginating tube 28 on the respective surfaces, these surfaces may be suitably roughened as by lcnurling, scoring, or the like.

Disposed within the tubular piston rod bore d?) adjacent to the free end thereof, may be a charging check valve assembly S9. The charginfy check valve assembly 59 includes a body member di having a threaded end portion which is screwed into the internally threaded end of the piston rod bore d3 and a forwardly projecting reduced end portion 53. The threaded end portion is formed with a reduced end 64 about which there is disposed a sealinU gasket such as an O ring which is compressed against a shoulder 67 and to form a leak proof seal.

Extending through the body el is a fluid charging passageway o3 including a closure cap chamber 69 into which a closure cap 7l is threaded when the device l@ has 4been charged with hydraulic fluid. Communicating at one end with the closure chamber 69 is a check Valve chamber 72 which communicates at its other with an orifice 73`which opens into the tubular piston rod bore d3.

Threadably fastened within the check valve chamber 72 is a valve seat member f'fthaving an orice 75 which provides communication between the closure cap chamber 69 and the check valve chamber 72. Normally urged in seating engagement over the orifice by means of a spring 77 is a ball check valve 73.

Securing the second cylinder head 42 on thetubular piston rod 39 is a fastening member 79 having an eX- ternally threaded portion 3ft which is screwed into the internally threaded end of the tubular piston rod 39. Projecting outwardly from and integral with the threaded portion di is a shank d2 which extends through an axial opening S3. Threaded on the outer end of the shank 87 which projects into a recess dei formed on the outer face of the second cylinder d?. is a nut Se which is tightened so that the end of the tubular piston rod 39 is rmly clamped within a recess S7 formed on the opposite face of the second cylinder head d2. ln order to facilitate the insertion of the cylinder fastening member 'I9 within the tubular piston rod 43, the forward face of the body may be provided with a pair of diametrically spaced openings St for receiving a spanning wrench, or the like.

The metering pin ld comprises a rod which may be of constant circular cross section along the major portion of its length to provide a metering section 89 and is formed with a threaded end 9i which is threadably fastened within an axial blind opening 92 formed on the inner side of the rst cylinder head i3. At the other end the metering pin ld is formed with an attachment projection 93 of substantially rectilinear section. Coaxially formed in the attachment projection 93 is an internally threaded hole The attachment projection 93 and the threaded hole 9d formed therein are provided to facilitate the attachment of the metering pin i4 to the cylinder head i8, as more fully to be described hereinafter.

The metering section 89 of the metering pin 115.- is slidable and extends through the piston head orifice Si and is formed along the length thereof with tintes 96 of gradually tapering depth as shown in PEG. 5. Upon relative f movement between the cylinder lll and the iiuid displacement means i3 as occurs upon application of an impact force at either the cylinder head it; or cylinder head 42 the piston head and the metering section S9 are moved relatively to each other so that the flow through the orice 5l as determined by the depth of flutes 96 at substantially any given distance of travel impacts a substantially constant force travel closure characteristic to the unit.

To achieve the substantially constant force travel characteristic the flutes 96 are designed to conform to the expression wherein AX is the orifice area of any given position x over the total nominal stroke or length of travel l of the device between its extended and or contracted position (substantially corresponding to the length of the surface in which the tiutes 96 are formed) and Ao is the initial orifice area defined by the orifice 51 and the flutes 96 at the beginning of the stroke under conditions where a completely rigid body is being cushioned from impact.

In accordance with the present invention a metering pin assembly tool 97 as shown in FIGS. 6-12 is provided to facilitate the assembly of the metering pin 14 within the cylinder 11.

The assembly tool 97 includes a hollow cylindrical tube or housing 98 adjacent one end of which there is fixed as by welding a pair of diametrically opposed hand grip members 99. Fixed to the other end of the housing 98 is a socket member 101 having a socket 102 which may be of rectilinear contour complementary to the metering pin attachment projection 93 as shown in FIGS. l0 and 12. A coaxial opening 103 providing communication between the housing bore 104 and socket 102 is formed in the inner end of the socket member 101.

Axially extending through the housing bore 104 is a retainer rod 106 having a threaded end 107 which is extendable through the opening 103 into the socket 102. At the other end7 there is fixed to the retainer rod 106 as by a force fit and welding a journal member 108 which turnably seats within the housing bore 104. The journal member 10S further includes an enlarged head 109 having a diameter at least as great as the outer diameter of the housing 98 to provide a shoulder 111 which is abuttable against the end of the housing 98 and thereby limits inward movement of the retainer rod 106 within the bore 104 as shown. Fixed across the top of the head 109 is a handle 112.

In accordance with the present invention, the sequence of the assembly of the cushion device 10 is arranged so that the components thereof may be utilized to facilitate the assembly of the metering pin thereto. To this end, the cylinder head is fixed to one end of the shell 17. The piston head 41 is fixed to the end of the piston rod 39 and a stop ring 121 is fixed to the piston rod 39 outward of the ports 44; and the intermediate cylinder head 22 may be slipped over the rod 39 for lengthwise movement. Also, the reversed end of the invaginating boot 28 is clamped to the piston rod 39 and the other end clamped to the boss.

The sub-assembly of the piston rod 39, piston head 41, invaginating tube 28, and intermediate cylinder head 22 is then inserted through the open end 113 of the cylinder 11 with the piston head 41 disposed adjacent the cylinder head 1S. The intermediate cylinder head 22 is then fixed within the cylinder by way of the snap ring 32. Thereafter, the bendable clips 37 are inserted through the openings 38 and straightened so that the slidably mounted ring member 34 is urged to the left as viewed in FIGS, 1 and 2 to compress the O ring 36 `against the shoulder 29.

The device 10 thus partially assembled is then supported vertically on the cylinder head 10 with the open end 113 extending upwardly preparatory to the insertion of the metering pin 14.

To fasten the metering pin within the cylinder the metering pin 14 is initially fastened to the assembly tool 97 prior to inserting the metering pin within the cylinder bore 12. This is accomplished by fitting the socket 102 in the socket member 101 over the rectilinear end section of the metering pin so the metering pin 14 is turnable with the housing 98. Thereafter, the retainer rod 106 is turned within the bore 104 of the housing so as to screw the threaded end 107 within the internally threaded opening 94 and thereby cause the attachment projection 93 to be drawn further into the socket 102 until the terminal face 114 thereof is firmly seated against a shoulder 116. In this manner the housing 9S of the tool 97 forms an extension of the metering pin 14 such that the overall length of the assembly tool 97 and metering pin 14 is greater than the overall length of the partially assembled unit as shown in FIG. 7.

The assembly tool 97 with the metering pin 14 attached thereto are then introduced through the bore 43 of the tubular piston rod 39 and through the piston head orifice 51. When thus inserted through the metering pin orifice 51 as shown in FIG. 7 the latter serves as a guide for the metering pin 14 and aligns the threaded end thereof with the blind threaded opening 92 in the cylinder head 1S. The assembly tool 97 is then turned by means of the handles 99-99 to screw the metering pin 14 into the opening 94 until firmly fastened therein.

Detachment of the assembly tool from the metering pin is accomplished by holding the housing 98 against turning the retainer rod 106 relative thereto to unscrew the threaded end 107 from the metering pin threaded opening 94 so that the socket member 101 is freely slidably out of seating engagement with the attachment projection 93 and the tool 97 withdrawn from the piston rod bore 43.

To complete the assembly of the device 10 the check valve assembly 59 with the closure cap 71 removed is inserted into the threaded end of the piston rod 59. Thereafter, the device 10 is charged with a suitable hydraulic fluid. The hydraulic iiuid flows through the closure cap chamber 69 and the orifice 76 past the unseated ball check 78 and through the fluid charging passageways 15 into the tubular piston rod bore 43 and into the low pressure chamber 117 of the cylinder bore 12 via the ports 44. At the same time the hydraulic fiuid fiows into the invaginating tube 2S via the annular opening 57 about the piston rod 39 and through openings 119 formed in the piston rod 39 inwardly of the reversed end i of the tube 28.

Fluid also flows through orifice 51 in the piston head 41 and the metering pin iiutes 96 into the high pressure chamber 118 of the device. The device 10 is charged to the extent that the pressure exerted by hydraulic fluid in the extended position of the device is maintained at a minimum, for example about 2 p.s.i.

To complete the assembly, the resilient return spring 16 is positioned about the cylinder and the second cylinder head 42 is fastened to the end of the piston rod 39. As heretofore described, the cylinder head 42 is fastened to the piston rod 39 by means of the fastener 75 which is threaded into threaded end of the rod 39 with the stud portion 82 to which the cylinder head 18 is fastened projecting outwardly. The resilient return spring 16 is generally formed lfrom a plurality of helical springs 16a, 16]), and 16e arranged to operate in tandem as shown. To fasten the cylinder head 42 on the stud 82 it may be necessary to employ a fixture or the like for holding the springs 16a, lb and 16e sufficiently compressed at 0r below the end of the rod 39 so that the second cylinder head 42 may .be fastened to the rod 39 without interference therefrom. After the spring is compressed the second cylinder head 42 is positioned on the stud 82 and the nut 86 is tightened. Thereaftenrthe spring fixture (not shown) may be removed so that the return springs 16a, 16h, and 16C are operative to maintain the cylinder 11 and fiuid displacement means 13 in the normal extended position shown in FIG. l.

Assuming that the hydraulic cushion device is employed in a railway car for the purpose for which it is primarily intended and is disposed between and operatively associated with the coupler carrying structure and the lading supporting surface for cushioning the force of impact applied on the coupler, the cushion device is normally in the fully extended position as shown in FIG. l. Upon the application of a shock impact in either buff or draft at the couplers, the cushion device 10 is associated with the coupler carrying structure and the lading structure such that either the cylinder 11 will start movement in the direction of piston head 41, or piston head 41 will asia osa i start movement toward cylinder head it), or possibly both movements will occur.

As the cushioning device l@ thus contracts und-er the torce being cushioned, the metering pin 14 displaces hydraulic fluid contained within the bore 43 of the piston rod 3% outwardly through the ports 44 into the low pressure chambers from where it flows via the annular opening S7 into the invaginating tube At the same time the piston head 4l displaces fluid in the high pressure chamber 18 through the oriiice Si into the piston rod bore 43. The hydraulic llow through the orice 5l is determined by its position relative to the ilutes 9d which as heretofore described are formed so as to impact a substantially constant resisting torce closure characteristic to the hydraulic cushion device lll. ln other words, the ilutes 96 of the metering pin are cooperative with the orifice 51 so that the flow of hydraulic huid during substantially each increment of travel of the piston head 4l relative to the cylinder llt results in a substantially constant cushioning eltect resisting the force of impact.

The hydraulic liow caused by the relative movement of the piston head 4l and the cylinder all as above described tlows from the high pressure chamber lid through the orifice Sil and into the bore 43 of the tubular piston rod 39. Hence, the hydraulic fluid ilows radially outward through the ports 4l into the low pressure chamber of the cylinder bore l2. The hydraulic flow through the ports 4l occurs at a relatively high velocity so that turbulence is created as the displaced fluid enters the low pressure chamber M7. The turbulence is caused at least in the part by the radially directed dow of the fluid impinging directly against the inner wall of the cylinder lll so that a major portion of the kinetic energy of the hydraulic iluid is dissipated in the form or" heat. ln this connection, it is to be noted that the stop ring lill contacting the intermediate cylinder head is eilective to limit the volume of the low pressure chamber l and in this manner provides a chamber into which the hydraulic fluid displaced by the piston may freely enter as described above and thereby dissipate the kinetic energy in the form of the heat under minimum shock or load conditions.

During contraction of the cushioning device l@ the high pressure chamber il@ continues to reduce in volume because of the advancement of the piston head il toward the cylinder head 18. The hydraulic tluid passing through the orice 5l lills the low pressure chamber A7, while at the same time a volume of hydraulic fluid equivalent to that displaced by the total entry into the chamber 117 of the cylinder ll passes threughthe annular opening and into the reservoir deined by the invaginating tube 28 which inllates or expands and assumes substantially the position shown in PG. 2.

After the shock has been `fully dissipated the compression springs loa, leb, and idc, acting in tandem between the cylinder heads ELS and 42 are operative to return the hydraulic cushion components to the initial position. During this movement, under the action of the compression springs, the hydraulic lluid flow previously described is reversed and the invaginating tube dellates and returns to the position shown in FIG. l, thereby assuring that the hydraulic fluid displaced by the piston head 4l is restored to its normal operative position.

What is claimed is:

in a hydraulic cushion device comprising a cylinder having a bore, a rst cylinder head ixed to'one end of said cylinder, an intermediate cylinder head xed Within said cylinder inwardly of the other end thereof, an axial opening in said intermediate cylinder head, a piston head disposed within said cylinder Abore for movement between said intermediate cylinder head and said rst cylinder head, an axial orilice formed in said piston head, a tubular piston rod fixed at one end to said piston head and eX- tending through said axial opening in said intermediate cylinder head, a ilexible reservoir connected between said intermediate cylinder head and said piston rod, means providing communication between said cylinder bore and said ilexible reservoir, and a second cylinder head fastened to the other end of said piston rod; the improvement comprising an axially threaded hole formed on the inner side and extending only partially through said irst cylinder head, and a metering pin coaxially disposed Within said cylinder, said metering pin being of lesser length than said tubular piston rod and including an intermediate portion of substantially uniform cross section along the length thereof and extending through said piston head orifice into said tubular piston rod, a threaded end formed on one end of said metering pin which is fastened in said threaded opening, and a projection of substantially rectilinear section formed on the remaining end of said metering pin for receiving a complementary socket head of an assembly tool adapted to be inserted through said piston rod prior to the fastening of said second cylinder head on said other end of said piston rod, said projection of rectilinear section having a centrally located threaded opening adapted to receive the threaded end of a retainer rod of the assembly tool.

leterences Eited by the Examiner UNTED STATES PATENTS 988,432 4/1911 Blakeslee `29-173 2,l67,928 9/1939 Johnson 18S-88 2,608,404 8/1952 Gruss 267-64 2,641,052 6/1953 Fennema et al. 29-240 2,668,347 2/1954 Gorske 29-173 3,031,180 4/1962 Sergay 267-34 3,935,827 5/1962 Peterson 213-43 X 3,064,340 11/1962 Green 29--240 3,148,869 9/l964 Peterson 18S- 96 X FOREGN PATENTS 1,052,624 l/l954 France.

ARTHUR L LA PONT, Primary Examiner.