US3399880A - Damped spring - Google Patents

Description

Sept. 3, 1968 R. L. CARLSON Filed Feb. 25, 1966 4 Qu, 7///////////////////// ///////VW |1T ,Q .www l N N ,E \\\\w\\\\\ Q QNI 1 w QW, l h k 1 w A ,www NT. mw QW MVT' United States Patent O 3,399,380 DAMPED SPRING Robert L. Carlson, Chicago, Ill., assignor to W. H. Miner Inc., Chicago, Ill., a corporation of Delaware Filed Feb. 23, 1966, Ser. No. 529,585 4 Claims. (Cl. 267-1) ABSTRACT F THE DISCLOSURE A damped spring having an elongated casing with a prim-ary chamber filled with a compressible solid eccentric to the longitudinal axis of the casing and receiving a piston, and a communicating auxiliary chamber whereby an additional volume of compressible solid is available whereby to accommodate increased travel of the piston and its associated piston rod.

My present invention relates generally to a damped spring and more particularly to a long travel damped spring.

In general, -a damped spring comprises casing means with a primary chamber therein, a piston rod extending outwardly of the primary chamber for receiving impact forces, and a piston at the end of the piston rod within the primary chamber. The piston provides axial orifice means, and the primary chamber is filled with a compressible solid. As the piston rod moves into the primary chamber in response to impact forces, the reduction in volume of the compressible solid, and the throttling effect produced by the compressible solid being forced through the orifice means, impose a damping and spring force on the piston rod and piston.

It is an object of =my present invention to provide a dambed spring, of the general type described, wherein the primary chamber that receives the piston communicates with an auxiliary chamber whereby additional volume of compressible solid is afforded to accommodate long travel of the piston rod.

It is another object of my present invention to provide a damped spring, as described, wherein the casing means thereof is elongated and the primary and auxiliary chambers are substantially coextensive in an axial direction. This general arrangement of the cham-bers contributes to compactness. p

It is a further object of my present invention to provide a damped spring, as described, wherein the casing means comprises a cylinder that defines the primary chamber and a surrounding casing that defines with the cylinder the auxiliary chamber. This specific construction additionally contributes to compactness.

-It is a still further object of my present invention to provide a damped spring, as described, wherein the primary and auxiliary chambers communicate through metering ports that serve to control the return force imposed on the piston rod as the compressible solid expands.

Now in order to acquaint those skilled in the art with the manner of constructing and using da-mped springs in accordance with the principles of my present invention, I shall describe in connection with the accompanying drawing, a preferred embodiment of my invention.

In the drawing:

FIGURE l is a longitudinal median sectional View of a damped spring incorporating the principles of my present invention;

FIGURE 2 is a transverse sectional view, taken substantially along the line 2-2 in FIGURE 1, looking in the direction indicated by the arrows; and

FIGURE 3 is a view, partly in elevation and partly in section, taken substantially along the line 3 3 in FIG- URE 1, looking in the direction indicated by the arrows.

3,399,880 Patented Sept. 3, 1968 ICC Referring now to the drawing, there is indicated generally by the reference nume-ral 10 a damped spring -incorporating the principles of my present invention. The damped spring 10 comprises an elongated casing 12 having a rear closed end wall 14, a forward end wall 16, and a forward cylindrical opening 18. The casing 12 is generally oblong in cross-section, and the axis of the opening 18 is eccentric to the principal longitudinal axis of the casing 12.

Disposed axially within the casing 12 is a cylinder 20. The forward end of the cylinder 20 is seated in the opening 18, While the rear end of the cylinder 20 is seated in a counterbore 22 formed in the rear casing wall 14 and abuts a plate 24. The casing 12 and cylinder 20 together servel as casing means. The cylinder 20 defines interiorly a primary chamber 26, and the casing 12 defines with the cylinder 20 an auxiliary chamber 28. The primary and auxiliary chambers are maintained in communication by a plurality of circumferentially spaced radial ports 30 that are formed in the cylinder 20 adjacent the rear casing wall 14.

Mounted in the casing opening 18 is guide and seal means indicated generally by the reference numeral 32. The guide and seal means 32 is comprised of an annular piston rod bearing or gland 34 having an inner end 36 of reduced diameter that is received in the forward end of the cylinder 20. The gland 34 carries an O-ring or seal 38 that engages the periphery of the casing opening 18, and also carries an annular packing or seal assembly 40. The gland 34 is maintained in proper axial position against the forward end of the cylinder 20 by means of four ring segments 42 engaged in an annular groove 44 formed in the casing wall defining the opening 18.

Extending through the gland 34 and the packing assembly 40, and projecting into the primary chamber 26, is a piston rod 46. The outer end of the piston rod 46 is adapted to receive impact forces, while the inner end of the piston rod has secured thereon a piston 48. The periphery of the piston 48 is spaced from the interior cylindrical surface of the chamber 26 to define axial orifice means in the form of an annular orifice. Additionally, the primary and auxiliary chambers 26 and 28 are filled with a compres-sible solid or elastomer 50 such as silicone rubber.

The rear casing wall 14 is formed with a charging port 52 having a conical valvel seat 54 that is engageable 4by a ball valve 56. The plate 24, which serves to retain the ball valve 54 within the confines of the inner end of the charging port 52, is provided with apertures 58 through which the charging port 52 communicates with the prima-ry chamber 26. The described ball check valve arrangement serves to permit the admission of compressible solid into the chambers 26 and 28, and yet prevents I the escape of compressible solid therefrom, for example, between the time that charging means (not shown) is removed from the outer end of the port 52 and a filler plug 60 is inserted therein. As shown in FIGURE 2, the casing 12 is provided with opposed lateral flanges 62 which are adapted to be secured by bolts 64 to a supporting frame 66.

In the operation of the damped spring 10, buff forces imposed on the piston rod 46 cause the latter and the piston 48 to move inwardly of the primary chamber 26 from the position shown in solid lines in FGURE l toward the position shown in dotted lines. During such move ment, the volume of the primary chamber 26V is reduced to the extent of displacement by the piston rod, thus increasing the pressure of the compressible solid 50 in both chambers 26 and 28. Concurrently, the compressible solid 50 is forced through the annular orifice surrounding the piston 48 thereby producing a throttling effect. The described volume-pressure change of the compressible solid,

and the attendant throttling effect, impose a damping and spring force on the piston and the piston rod, and thereby serve to dissipate the energy of the buff forces imposed on the piston rod 46.

The compressible solid 50 is initially precompressed or preloaded approximately 3% and the corresponding internal pressure is about 5,000 p.s.i. When the piston rod 46 reaches the innermost end of travel shown in dotted lines, the compressible solid is compressed an -additional 8-l2% and the corresponding internal pressure is then about 35,000 p.s.i. Because of the provision of the auxiliary chamber 28 which affords additional volume of compressible solid, the reduction in volume of the compressible solid `caused by piston rod displacement is limited as indicated, and long travel of the piston rod is accommodated. Furthermore, because the primary and aux. iliary chambers 26 and 28 are arranged substantially coextensive in an axial direction and are defined by the casing 12 and cylinder 20 in the manner described, long travel of the piston rod is attained in a compact construction.

When the buff forces are removed from the piston rod 46, or are otherwise fully dissipated, the pressure of the compressible solid 50, acting on the unbalanced area of the piston rod 46, Causes the piston 48 and piston rod 46 to return to the solid-line position shown in FIGURE 1. During the return stroke of the piston rod 46, the compressible solid flows back through the annul-ar orifice surrounding the piston 48 to fill the space being vacated by the latter. Correspondingly, the pressure f the compressible solid 50 returns to the normal preload pressure. In this connection, the preload pressure serves to assure positive return of the piston rod and piston to the normal rest position shown in solid lines. Finally, the ports 30, which may be varied in size, serve to meter compressible solid therethrough and thereby control the return force imposed on the piston rod as the compressible solid expands.

While I have shown and described what I believe to be a preferred embodiment of my present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of my invention.

I claim:

1. A damped spring comprising a horizontally disposed generally elongated casing which is generally oblong in a vertical direction, one end of said casing being closed by a rear wall and the opposite end being provided with a partial end wall defining a circular opening in the upper portion of the casing, a cylinder and piston unit mounted in the upper portion of said casing with a piston rod projecting outwardly of said opening and adapted to receive impact blows, the inner end of said cylinder being ported to provide communication between a primary chamber defined within said cylinder and an auxiliary chamber defined by the inner surface of said casing and the outer surface of said cylinder, axially extending orifice means in the piston of said cylinder and piston unit, and a compressible solid filling both said primary and auxiliary chambers whereby compression of said compressible solid upon inward movement of said piston and piston rod provides both a damping and reutrn force on said piston, said axially coextensive auxiliary chamber providing a greater volume of said solid to be compressed whereby to permit a greater inward travel of said piston and rod for a given length casing and cylinder.

2. The damped spring of claim 1 wherein the inner end of said cylinder is seated in a recess provided on the inner surface of said casing rear Wall and the outer end of said cylinder is seated in said circular opening defined by said partial end wall, and wherein annular guide and seal means is disposed in said circular opening defined by said partial end wall and in the adjacent end of said cylinder for guiding and sealing said piston rod.

3. The damped spring of claim 2 wherein said ported inner end of said cylinder comprises a series of circumferentially spaced radial ports whereby to provide communication between said primary and auxiliary chambers.

4. The damped spring of claim 1 wherein said axially extending orifice means in said piston comprises an annular orifice defined between the periphery of said piston and the inner surface of said cylinder, and wherein a ball-check-valve controlled charging port for filling said chambers with said compressible solid is provided in said casing end wall.

References Cited UNITED STATES PATENTS 2,778,627 l/1957 Sands 267-1 3,053,526 9/1962 Kendall 267-64 3,152,798 10/1964 Jarret et al. 267-1 3,294,391 12/1966 Smith et al 267-64 3,306,598 2/1967 Jarret et al 267-64 FOREIGN PATENTS 299,872 8/ 1965 Netherlands.

ARTHUR L. LA POINT, Primary Examiner. R. M. woHLFARTH, Assisfam Examiner.

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