US3216591A - Hydraulic cushion return spring arrangement - Google Patents

Description

Nov. 9, 1965 w, H. PETERSON HYDRAULIC CUSHION RETURN SPRING ARRANGEMENT Filed Jan. 2s, 1964 6m m SVRAAM.

l N m` N3 TNVENTOR. lo@ w w Nov. 9, 1965 w. H. PETERSON HYDRAULIC CUSHION RETURN SPRNG ARRANGEMENT Filed Jan. 2s. 1964 2 Sheets-Sheet 2 ERSON United States Patent 3,216,591 HYDRAULIC CUSHIN RETURN SPRING ARRANGER'ENT William H. Peterson, Homewood, lil., assigner to Pullman Incorporated, Chicago, Ill., a corporation of Delaware Filed Jari. 23, 1964, Ser. No. 340,632 3 Ciaims. (Cl. 213-43) The present invention relates to hydraulic cushion devices and more particularly to a new and improved return spring arrangement for a hydraulic cushion device of the type which comprises essentially two relatively reciprocating components having hydraulic iiuid arranged therebetween so as to be operative upon the application of an impact force causing relative contraction of the components to absorb a portion of the kinetic energy of the impact.

The cushion device to which the improvement of the present invention relate-s includes generally a fluid-filled cylinder having a closed end and an open end. Reciprocable within the cylinder is a fluid displacement means including a piston head fixed to one end of a piston rod which extends outwardly of the open end of the cylinder. Disposed inwardly of the open end of the cylinder is an intermediate cylinder head having iiuid passage means. Connected between the intermediate cylinder head and the piston is a liexible boot reservoir into which the hydraulic uid ows from the cylinder bore through the passage means of the intermediate cylinder.

Fixed to the outer end of the piston rod is a cylinder head, and disposed between the latter and a cylinder head which forms the closed end of the cylinder is a return spring means.

The present invention proposes to provide a new and novel return spring means arrangement for facilitating the assembly and disassembly of a hydraulic cushion device of the above general type.

It is a further object to provide a hydraulic cushion device with a return spring arrangement wherein the return spring is supported by a telescoping open frame housing which is disposable between the cushion device cylin der heads so as to contract upon relative impact to the device and extend to a limit position corresponding to the normal or neutral position of the components under the force of the spring when the impact has been dissipated.

Further objects and features will hereinafter appear.

In the drawings:

FIG. 1 is a side elevational view of the cushion device embodying the return spring arrangement of the present invention;

FIG. 2 is a fragmentary enlarged cross-sectional View of the cushion device shown in FIG, 1, but showing the components in the contracted position;

FIG. 3 is an enlarged fragmentary view partially in cross-section taken generally along the lines 3-3 `oi TIG. l;

FIG. 4 is an enlarged fragmentary view partially in cross-section taken generally along the lines 4 4 of FIG. 2;

FIG. 5 is a cross-sectional View taken generally along the lines 5 5 of FIG. 2; and

FIG. 6 is a perspective View of the return spring housing.

Referring now in particular to FIGS. 1 and 2, there is shown a cushion device 1i) embodying the present invention including generally a cylinder 11 having a bore 12 which is charged with a `suitable hydraulic iiuid, a fluid displacement means or piston-piston rod assembly 13 reciprocable Within the cylinder 11 between the normal fully extended position (FIG. l) and a contracted position (FIG. 2) upon the application of an impact force to the 3,216,591 Patented Nov. 9, 1965 ICC` device and being operative to displace iiuid within the bore 12 to dissipate a portion of the kinetic energy of the impact force; a metering pin 14 for controlling the rate of displacement of the uid within the bore 12 to provide an approximate constant force travel closure characteristic to the device; and a resilient return spring arrangement 16 disposed between the tluid displacement means 13 and the cylinder 11 for returning the components to their fully extended position upon dissipation of the impact force.

The cylinder 11 includes a tubular shell 17 formed preferably from a rigid metallic preformed tube capable` otwithstanding the internal lpressures to which the cylinder is subject during use. The shell 17 may be formed of cold drawn steel tubing of which 4the inner wall is formed with a smooth inish to permit eiiicient operation of the duid displacement means 13 therein.

The shell 17 is closed at one end by a cylinder head 18 having a groove 19 formed on the inner face thereof for receiving the end of the shell and the latter is fixed therein as by welding to form a leak-proof joint. The cylinder head 18, which may be either circular or rectilinear, as shown, is sized to project outwardly of the outer diameter 'of the shell 17 to form a retaining ledge 21 against which one end of the resilient return spring arrangement 16 abuts.

As shown, the other end of the shell or tube 17 may be formed with a boot chamber bore 22 of larger diameter than the bore 12. Disposed within the bore 12 is an intermediate cylinder head 23 having an axial opening 24. The intermediate cylinder head 23 may be formed at the inner end which abuts a shoulder 26, with an inner section 27 having an outer diameter substantially equal to the diameter of the boot chamber bore 22, an intermediate section 28 of somewhat lesser outer diameter out'- wardly -of the inner section 27, and a boss 29 on which one end of a iiexible boot reservoir or invaginating tube 31 is secured as more fully -to be explained hereinafter.

Fixing the intermediate cylinder head within the boot chamber bore 22 is a snap ring 32 disposed within a groove formed in the inner wall. The snap ring 32 is engageable with a collar 33 threadably Jfastened on the outer end of the intermediate section 28 such that the inner end of the intermediate cylinder head 22. is held iirmly engaged with the shoulder 26.

Disposed between a metal compression ring 34 slidable on the intermediate section 28 and the outer shoulder 36 of the inner section is a sealing gasket such as an O-ring 37. Compressing the O-ring 37 between the compression ring 34 and the shoulder 36 so that a substantially fluidtight seal is formed at the innei wall of the bore 22 are a plurality of radially spaced bendable clip members 38. The bendable clip members 38 are initially inserted between the collar 33 and the compression ring 32 in a bent condition and after the intermediate cylinder head 22 has been fastened within the bore 12 by means of the snap ring are flattened.

Access to the clips 38 to straighten the latter is achieved through complementary radially spaced openings 39. Upon straightening of the clips 38 the compression ring 34 is urged toward the shoulder 36 such that the O-ring 37 is compressed therebetween and thus causes the latter to radially expand and sealingly engage the inner wall of the bore 22. In this manner a substantially duid-tight seal is formed at the intermediate cylinder head. For a more detailed description of the arrangement for fastening the intermediate cylinder head 22 into the cylinder bore 12, reference is made to U.S. patent application Serial No. 337,193, filed January 13, 1964, and assigned to the assignee of the present invention.

The fluid displacement means 13 includes the piston rod 41 to one end of which there is fixed a piston head 42 which is reciprocable within the bore 12 between the cylinder head 18 and the intermediate cylinder head 23. Fastened to the other end of the piston rod 41 is a second cylinder head 43.

The piston rod 41 is of hollow construction including a bore 44 and may be formed of a rigid material such as cold drawn steel. Radially spaced ports 46 are formed in the piston rod 41 adjacent to the piston head 42 for providing communication between the piston rod bore 44 and the cylinder bore 12.

The piston head 42 is preferably formed from a metal such as steel and comprises a dish-like body having a planar forward face 47 and a planar rearward face 48. The planar rearward face merges it into a conical feed surface 49 which terminates in a rim 51 which defines the perimeter of an orifice 52 formed axially in the piston head 42. The piston head 42 is formed on its forward face 47 with a recess which receives the terminal end of the tubular piston rod 41 and the latter is ilxed thereto as by welding.

For guiding the fluid displacement means 13 for reciprocation within the cylinder bore 12 and for forming a seal between the inner wall of the cylinder and the piston head 42, the piston head is provided with an elevated seal forming and guiding member 53. The member 53 is formed as a split ring which is seated within a peripheral grooved formed on the periphery of the piston head. Preferably the ring member 53 is made from a laminated phenolic resin.

The tubular piston rod 41 is of lesser diameter than the diameter of the axial opening 24 in the intermediate cylinder head 23 so as to dene an annular opening 54 which provides communication between the bore 12 and the flexible boot reservoir 31. The flexible boot reservoir 31 may be formed from a fluid-impervious flexible material which is capable of resisting the corrosive or deteriorating effects which may be present in the hydraulic lluid employed in the device and advantageously may be a neoprene-buna type of rubber having special additives for low temperatures flexibility. The boot reservoir 31 is fixed at one end to the boss 29 of the intermediate cylinder head by means of a hose clamp and its other end is reversely bent and similarly fixed to the tubular piston rod 41.

Disposed within the tubular piston rod bore 44 adjacent the outer end thereof, is a charging check valve assembly 56. For a more detailed description of the check valve assembly 56 reference is made to U.S. patent application Serial No. 318,384, led October 23, 1963, and assigned to the assignee of the present invention.

Fastening the second cylinder head 43 on the tubular piston rod is a fastening member 59 having an enlarged externally threaded inner portion 58 which is screwed into the internally threaded end of the tubular piston rod 41. Projecting outwardly from and integral with the threaded body portion is a shank 59 which extends through an axial Opening 61 formed in the second cylinder head. Threaded on the end of the shank 59 projecting into recess formed on the outer face of the second cylinder head 43 is a lock nut arrangement 62 which is tightened so that the end of the tubular piston rod is firmly clamped within a recess 63 formed on the inner face 64 of the second cylinder head 43. In order to facilitate the insertion of the cylinder fastening member 57 within the bore 44 of the tubular piston rod 41, the forward face may be provided with a pair of diametrically spaced openings 66 for receiving a spanning wrench, or the like.

The metering pin 14 comprises a rod having a section of substantially constant circular cross-section area along the major portion of its length and is formed with a threaded end 68 which is threadably fastened within an axially blind opening 69 provided on the inner side of the first cylinder head 18. At the other end the metering pin 14 is formed with a fastening projection 71 of substantially rectilinear section in which there is formed a coaxially disposed threaded opening 72. The rectangular projection 71 `and threaded opening 72 therein are provided to facilitate the attachment of the metering pin 14 Within the device 10 as more fully described in my aforementioned copending application Serial No. 337,193 to which reference is made.

A section 67 of the metering pin 14 extends through the piston head oriilce S2 and is formed along the length thereof with flutes 73 of gradually tapering depth.

Upon relative movement between the cylinder 11 and the fluid displacement means 13, as occurs upon application -of a force at either cylinder head 18 or cylinder head 43, the piston head 42 and metering pin 14 are positioned relatively to each other so that the tlow through the ori'ice 52 as determined by the depth 0f ilutes 73 at substantially any given distance of travel imparts a substantially constant force closure characteristic to the unit.

To achieve the substantially constant force characteristic the flutes 73 are designed to conform wherein AX is the orilice area of any given position X, over the total nominal stroke or length of travel L of the device between its extended and contracted positions (substantially corresponding to the length of the surface in which the llutes are formed) and A0 is the initial orilice area defined by the orifice 52 and the flutes 73 at the beginning of the stroke under conditions where a completely rigid body is being cushioned from impact.

Disposed between the cylinder heads 18 and 43 is the return spring arrangement 16 of the present invention. The return spring arrangement 16, includes as shown in particular in FIGS. 3-6, an open frame or cage 75 including an end plate 74 formed with a circular opening 76 which has a diameter substantially equal to the outer diameter of the cylinder shell 17 so as to be slidable thereover as shown in FIGS. l and 2. Fixed to and extending from the corners of the inner wall of the end plate 74 are horizontal tubular members 77 which telescopingly receive Within the respective bores thereof shafts 78 which are xed adjacent to corners of a second end plate 79. The second end plate 79 is provided with an opening 81 which is sized so as to be received by a boss 82 formed on the inner side of the second cylinder head 43.

As shown in FIGS. 3 and 4, the ends of the shafts 78 are each formed with enlarged heads 83 so as to be telescopingly slidably guided within the bore 84 of the tubular members or shafts 77. Fixed in the ends of each of the tubular members 77 is a stop collar 86 which limits the extension of the housing 16 as shown in FIG. 3.

Disposed within the housing 75 between the end plates and encircling the cylinder 11 is a compression spring 87 which may be a single spring or a plurality of compression springs acting in tandem.

As shown in FIGS. l and 3, the maximum extended length of the housing 75 as determined by the engagement of the heads 83 with the stop collars 86 is such that the compression spring 87 is operative to return the components of the device to the neutral position shown in FIG. l from the contracted position of FIG. 2 as more fully to be explained below. Moreover, in the fully extended or maximum extended position of the housing 75 the spring 87 is partially compressed, but is held xed against further extension by means of the head 83 abutting the stop collars 86.

Heretofore, in the absence of the return spring arrangement of the present invention, the Cylinder head 43 is attached on the piston rod 41 after the return spring is disposed about the cylinder 11 of the partially assembled cushion device 10. The return spring when thus disposed is of greater length than the fully extended length of the cushion device such that the return spring must be partially compressed to permit the fastening of the cylinder head 43 on the end of the piston rod 41. This is accomplished by a fixture which is removed after the attachment of the cylinder head 43 is made.

However, with the spring arrangement 16 of the present invention the housing 75 serves to hold the compression spring 87 partially compressed and shortened such that a separate fixture is not necessary. The return spring housing 75 retaining the compression spring 87 between the end plates 74 and 79 is disposed over the partially assembled cushion device with the end plate 79 embracing the cylinder 11 and abutting against the inner wall 21 of the cylinder head 18. When thus positioned, the overall length of the housing 75 is such that the shank 59 of the fastening member 57 extends beyond the outer face of the follower plate 79. The cylinder head 43 then may be slipped over the shank 59 and the boss 82 inserted into the opening of the end plate 78. Thereafter, the locknut arrangement is threaded on the end of the shank 59 and tightened to the extent necessary to fasten the cylinder head 43 on the end of the piston rod 41.

A further advantage of the return spring arrangement 16 is apparent during disassembly of the cushion device 10. Heretofore, in the absence of a housing 75, as when the spring means is disposed in direct contact between the follower plates 18 and 43, removal of the follower 43 results in a rapid extension of the spring from its partially compressed position. This rapid extension creates a dangerous condition because the force of the extending spring could readily injure the laborer performing the disassembly or cause further damage to the unit itself. With the present invention, the housing 75 precludes further extension of the spring 87 beyond the maximum extended length between the plates 74 and 79 such that any dangerous conditions are eliminated.

From the foregoing, it should be readily apparent that the assembly and disassembly of the cushion device is expedited and greatly facilitated.

Assuming that the hydraulic cushion device 10 is employed in a railway car of 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 device 10 is normally in the fully extended position as shown in FIG. 1. Upon the application of a shock impact in either buit or draft at the couplers, the device 10 which is associated with the coupler carrying structure and the lading supporting structure such that the cylinder 11 and piston head 42 start movement toward each other.

As the cushioning device thus contracts under the force being cushioned, the metering pin 14 displaces hydraulic uid contained within the bore 44 of the piston rod 41 outwardly through the ports 46 into the low pressure chamber 88 from where it flows via the annular opening 54 into the invaginating tube 31. At the same time the piston head 42 displaces fluid in the high pressure chamber S9 through the oriiice 52 into the piston rod bore 44. The hydraulic ow through the orice 52 is determined by its position relative to the utes 73 which, as heretofore described, are formed so as to impart a substantially constant resisting force closure characteristic to the hydraulic cushion device. In other Words, the utes 73 of the metering pin are cooperative with the orifice 52 so that the iiow of hydraulic fluid therethrough for substantially each increment of travel of the piston head 42 relative to the cylinder 11 results in a substantially constant cushioning effect resisting the force of impact.

The hydraulic flow caused by the relative movement of the piston head 42 and the cylinder 11, as above described, iiows from the high pressure chamber 89 through the oriiice 52 and into the bore 44 of the tubular piston rod 41. Hence, the hydraulic Huid flows radially outward through the ports 46 into the low pressure chamber 88 of the cylinder -bore 12. The hydraulic ilow through the ports 46 occurs at a high velocity so that a turbulence is created as the displaced fluid enters the low pressure chamber 88. The turbulence is caused, at least in part, by the radially directed ow of the fluid impinging directly against the inner wall of the cylinder 11 so that a major portion of the kinetic energy of the hydraulic fluid is dissipated in the form of heat. In this connection, it is to be noted that the stop ring 91 contacting the intermediate cylinder head 23 is effective to limit the volume of the low pressure chamber 88 and in this manner provides a chamber into which the hydraulic fluid displaced by the piston head 42 may freely enter as described above and thereby dissipate the kinetic energy in the form of heat under minimum shock or load conditions.

Upon further contraction of the cushioning device the high pressure chamber 89 continues to reduce in volume because of the advancement of the piston head 4Z toward the cylinder head 18. The hydraulic fluid passing through the orifice 52 tills the low pressure chamber 83, while at the same time a Volume of hydraulic uid equivaient to that displaced by the total entry into the chamber 88 of the cylinder 11 passes through the annular opening 54 and into the reservoir deiined by the invaginating tube 31 which initiates or expands and assumes substantially the position shown in FIG. 2.

During the above described relative contraction of the iiuid displacement means 13 and the cylinder 11, the open frame housing disposed between the cylinder heads 18 and 43 telescopes inwardly and compresses the compression spring means 87 therebetween. The shafts 7 8 slide inwardly within the respective bores 84 of the tubular shafts 77 until the device 10 is completely contracted and the shafts 78 and tubular shafts 77 assume the position shown in FIG. 4.

After the impact force has been dissipated, the compression spring 87, acting between the end plates 74 and 79, is operative to extend the tubular shafts 77 and shafts 78 relatively to each other to the fully extended position shown in FIG. 3. The end plates 74 and 79 engaging the respective cylinder heads 18 and 43 fixed to the cylinder 11 and piston rod 41 are operative under the iniiuence of the compression spring to return the units to the neutral position.

What is claimed is:

1. In a hydraulic cushion device comprising a hydraulic fluid-filled cylinder having an open end, a tirst cylinder head closing the other end of said cylinder, a piston head reciprocable within said hydraulic fluid-filled cylinder for relative movement therewith between a neutral position adjacent said open end and a contracted position adjacent said iirst cylinder head and defining within said cylinder a high pressure chamber and a low pressure chamber, said piston head having an orifice, a metering pin fixed to said cylinder and extending through said orifice for Varying the eifective oriice area thereof Whereby said piston head is operative upon reciprocation from said neutral position to said contracted position to displace hydraulic uid within said cylinder from said high pressure chamber to said low pressure chamber in a manner causing kinetic energy to be dissipated, rod means xed at one end to said piston head for movement therewith, said rod means extending outwardly through said open end of said cylinder, a flexible boot reservoir iixed between said cylinder and said rod means closing oi said open end of said cylinder and a second cylinder head xed to the outwardly extending end of said rod means; the improvement comprising a lengthwise telescoping return spring cage including a first end plate and a second end plate adapted to engage said iirst and second cylinder heads, respectively, spaced telescoping means forming an open frame connecting said iirst and second end plates so that said cage is extendable and contractable upon relative movement of said cylinder and said piston head, and return spring means disposed about said cylinder and within said cage and in abutting engagement at opposite endsthereof with said rst and second end plates and being operative to extend said telescoping cage to a neutral position corresponding to said neutral position of said Acylinder and piston from said contractedv position said telescoping means including means limiting the extension of said -rst and second end plates to correspond to said -neutral position of said cylinder and said piston head.

2. The improvement as dened in claim 1 wherein said -telesco'ping lmeans comprises a tubular shaft xed to one of 'said end plates and the other of said telescoping members comprises a shaft means slidable Within the bore of 'limit means disposed within said tubular shaft bore to limit the extension of said spring housing to correspond to said 'neutral position of said cylinder and said piston head.

References Cited by the Examiner UNITED STATES PATENTS 4/64 Trautman et al. Z13-43 9/64 Peterson 267-1 ARTHUR L. LA POINT, Primary Examiner.

EUGENE G. BOTZ, Examiner.

Claims (1)

1. IN A HYDRAULIC CUSHION DEVICE COMPRISING A HYDRAULIC FLUID-FILLED CYLINDER HAVING AN OPEN END, A FIRST CYLINDER HEAD CLOSING THE OTHER END OF SAID CYLINDER, A PISTON HEAD RECIPROCABLE WITHIN SAID HYDRAULIC FLUID-FILLED CYLINDER FOR RELATIVE MOVEMENT THEREWITH BETWEEN A NEUTRAL POSITION ADJACENT SAID OPEN END AND A CONTRACTED POSITION ADJACENT SAID FIRST CYLINDER HEAD AND DEFINING WITHIN SAID CYLINDER A HIGH PRESSURE CHAMBER AND A LOW PRESSURE CHAMBER, SAID PISTON HEAD HAVING AN ORIFICE, A METERING PIN FIXED TO SAID CYLINDER AND EXTENDING THROUGH SAID ORIFICE FOR VARYING THE EFFECTIVE ORIFICE AREA THEREOF WHEREBY SAID PISTON HEAD IS OPERATIVE UPON RECIPROCATION FROM SAID NEUTRAL POSITION TO SAID CONTRACTED POSITION TO DISPLACE HYDRAULIC FLUID WITHIN SAID CYLINDER FROM SAID HIGH PRESSURE CHAMBER TO SAID LOW PRESSURE CHAMBER IN A MANNER CAUSING KINETIC ENERGY TO BE DISSIPATED, ROD MEANS FIXED AT ONE END TO SAID PISTON HEAD FOR MOVEMENT THEREWITH, SAID ROD MEANS EXTENDING OUTWARDLY THROUGH SAID OPEN END OF SAID CYLINDER, A FLEXIBLE BOOT RESERVOIR FIXED BETWEEN SAID CYLINDER AND SAID ROD MEANS CLOSING OFF

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