US2721580A

US2721580A - Bladder type pressure accumulator

Info

Publication number: US2721580A
Application number: US194267A
Authority: US
Inventors: Edward M Greer
Original assignee: Greer Hydraulics Inc
Current assignee: Greer Hydraulics Inc
Priority date: 1950-11-06
Filing date: 1950-11-06
Publication date: 1955-10-25
Anticipated expiration: 1972-10-25

Description

Oct. 25, 1955 E. M. GREER BLADDER TYPE PRESSURE ACCMULATOR Filed Nov. 5, 1950 lNvENToR EdwadMGpeef Y I l Mam/AM ATTORNEYS United States Patent Office 2,721,580 Patented Oct. 25, 1955 l BLADDER `TYPE PRESSURE ACCUMULATOR Edward M. Greer, West Hempstead, N. Y., assigner to Greer Hydraulics, Inc., a corporation of New York Application November 6, 1950, Serial N o. 194,267

Y 1 Claim. (Cl. 13S-30) When an accumulator of the bladder type is charged with liquid, the side wall of the gas charged bladder may fold over its inlet with consequent extrusion through such inlet resulting in puncture of the bladder with lea'kage of gas and failure of the device.

Leakage of gas may alsooccur at the usual valve, which may be of the Schrader type, mounted in the rigid air inlet of the accumulator casing, and intended to sustain the pressure within the bladder. As a result, the gradual bleeding of air from the bladder will cause failure of the device.

It is accordingly among the objects of the invention to provide a rugged and durable bladder for pressure accumulators, which may be molded in a single integral piece from resilient material such as rubber, natural or synthetic, and which will collapse under the pressure of `the liquid with which the accumulator is charged, in manner to guard against extrusion of the bladder wall into the rigid air inlet and the air inlet of which will automatically seal when the bladder is charged.

According to the invention, the bladder has an inlet nozzle extending thereinto, preferably formed integral therewith and desirably resilient and deformable so that upon charging of the accumulator, if the side wall of the collapsed bladder should contact the nozzle, it will bend the latter, and the interposition of the sealed, relatively thick nozzle precludes extrusion of the wall of the bladder through the rigid air inlet.

The outer Wall of the nozzle inherently has a considerably greater area against which pressure may be exerted than the wall of the bore and the wall of the nozzle at the tip end thereof is desirably made relatively thin so that it will offer less resistance to pressure exerted thereagainst than the remaining portion thereof. Thus, the flow of air as it is pumped into the bladder through the nozzle, will keep its bore open, but once the How of air is stopped, as the static pressure exerted within the bladder against the outer Wall of the nozzle will therefore be considerably greater than that exerted against the Wall of the bore, the nozzle will be compressed to close its bore, first at the thin tip end, thereby to provide an air tight seal.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. 1 is a View in longitudinal cross section of an accumulator incorporating the invention herein, and

Fig. 2 is a fragmentary sectional view on a larger scale of the bladder showing the air inlet nozzle thereof.

Referring now to the drawings, the pressure acculator comprises a container or pressure vessel 11, preferably of strong, rigid material such as steel, cast aluminum or the like, capable of withstanding high pressure and having an air inlet port 12 and an oil port 13 therein preferably opposed to each other. The container 11 may be spherical or cylindre-spherical as shown and has a partition intervening between the air inlet port 12 and the outlet port 13.

The partition is preferably a collapsible and expansible bladder 14, of resilient material such as rubber 0r Synthetic plastic of like physical characteristics, which in distended but substantially unstretched condition is smaller than the cavity of the container 11. Although the bladder 14 could be of any suitable shape, as shown in Fig. l, it desirably is substantially conical in contour along its length with the thickness of the bladder wall preferably gradually increasing from the larger diameteror mounted end thereof shown at the top to the opposite end thereof, the latter end being preferably thickend as at 16.

A nozzle 18 of resilient deformable materialis desirably molded integrally With a thickened portion-17 at the mounted end of the bladder and extends axiallyV thereinto. axially therethrough, the outlet end 21 of which extends through the tip 22 of the nozzle 18 into the'bladder 14- and the inlet end 23 of which is coaxial with the circular floor 2S of a substantially cylindrical recess 26, of diameter considerably greater than the diameter of the bore 19, formed inrsaid thickened portion 17 of thebladder and a peripheral groove 2S extends outward from recess 26 in the plane of the floor 25. The dimensions of the nozzle 13 should be so selected that the area of the outer wall 31 is sufficiently greaterably greater than the length of the Wall of the bore 19 from inlet 23 to the tip of the nozzle. Desirably the junction of the thickened portion 17 and the outer wall of said nozzle adjacent the root end-thereof is curved inwardly from said root end toward the tip of said nozzle as at 30 to avoid any sudden increase in crosssection7 thereby reducing the likelihood of tearing of the nozzle under the application thereto in use of repeated bending stresses.

Though the nozzle 21 could be of any suitable dirnensions, depending upon the size of the bladder in which it is incorporated, in the embodiment herein shown to illustrate the invention, the diameter of the base 32 thereof, which illustratively occupies only a part of thickened portion 17, as shown in Fig. 2, is approximately 13/8 inches and the nozzle has a length of approximately one inch. The bore 19 desirably has an internal diameterof approximately figg of an inch and the outer diameter of the tip 22 of the nozzle is approximately 1/s of an inch, and as shown in the drawings, the slope of the outer wall 31 of the nozzle from a point 33 substantially midway between the tip 22 and the base 32, to said tip is approx-` imately 30 degrees. Such dimensions are suitable for a bladder having an overall length of approximately 1'1 inches and a maximum external diameter of approxi-- tion 3 6 with a base disk presenting an outstanding lateralv flange 37 at one end thereof, which desirably is molded rigidly with the bladder in the peripheral groove 28 of the The nozzle 18 has a bore or passageway 19V 3 thickened portion 17 thereof. The base disk has a small central perforation 41 coaxial with the bore 38 of fitting 35 and in registry with inlet 23 of the nozzle. The stem portion 36 of the fitting desirably is of enlarged diameter as at 42 near the flange end thereof, to be encompassed snugly by recess 26 of the bladder and the protruding end of said stem is externally threaded as at 43 so that when the parts are assembled as shown in Fig. 1, the bladder may be securely clamped in place by means of a nut 44 screwed upon the protruding threaded stem of the fitting.

Desirably parts of the bladder about recess 26 protrude beyond the upper end of the enlarged portion 42, illustratively as shown in Fig. 2 by a plurality of concentric annular bosses 46 preferably molded integrally with the bladder, coaxial with and extending slightly above the enlargement 42. Thus, when the nut 44 is tightened and the ange 37 compresses the rim portion 45 against the undersurface of the container about the rim 47 of the air inlet port 12, the bosses will be compressed to the level of shoulder 42 to insure an air and liquid tight seal, yet by reason of the clamping of rim 47 by nut 44 and shoulder 42', cutting of the rim portion 45 of the bladder by excessive tightening of the nut is avoided.

Although the outlet port 13 of the accumulator could be controlled in any suitable manner, in the embodiment herein shown, it is preferred to use the general construction shown in Patent No. 2,469,171 dated May 3, 1949, by the use of which an outlet closure assembly 51 affixed in said port 13 may be removed without likelihood of injury to the mechanic. As shown in Fig. 1, this assembly desirably comprises a housing 52, preferably a tubular member which desirably has an external annular shoulder 53 at the upper end thereof. A locking member 54, illustratively a ring of greater outer diameter than said port 13 and deformable to permit its insertion thereinto, encompasses said tubular member and is seated on the rim 55 of port 13, the inner diameter of said ring 54 being less than the outer diameter of shoulder 53 so that said shoulder may seat on said ring. Encompassing said tubular member and in juxtaposition with said port 13 is a rubber gasket 56 which serves effectively to prevent leakage between the wall of port 13 and the outer wall of tubular member 52 when a nut 57 is screwed on the externally threaded portion 58 of said tubular member 52.

Desirably positioned in said tubular member 52 is a poppet valve comprising a valve head 61 adapted to seat on the beveled mouth 62 of tubular member 52 and having a stem 63 preferably formed integral therewith. Stem 63 is slidably mounted in bearing openings 64 and 65,

desirably in a pair of spaced

disks

67 and 66 mounted in 63 between head 61 and disk 67. As the construction and i.

operation of said outlet closure assembly per se forms no part of this invention it will not be further described.

With the construction thus described, the bladder 14 may initially be inflated as by means of a source of compressed air applied to the fitting 35. The incoming air will pass through the bore 3S of the fitting, through aligned openings 41 and 23 and through the bore 19 in the nozzle 18 in the bladder to iniiate the latter under desired high pressure. As air is forced through the bore 19 of nozzle 18 it will retain said bore open. When the iiow of air ceases, as the outer wall 31 inherently has a greater area against which pressure is being exerted, a greater load will be exerted against such outer wall than is exerted against the wall of the bore of the nozzle. As a result, the nozzle will be squeezed, causing its bore to close. Inasmuch as the thin tip end 22 of the nozzle offers less resistance than its remaining portion, such thin tip end will close first, thereby making an effective air seal which will eliminate any bleeding of air from the bladder.

If it is desired deliberately to bleed air from the inflated bladder, it is a relatively simple matter to insert a tube (not shown) through the bore in the nozzle thereby to provide a passageway through which air may escape.

As oil under pressure is forced into the container through tubular member 52, it will gradually compress the air in the bladder 14 which may assume the position shown in dot and dash lines in Fig. l. As the side wall of the bladder collapse, it may fold over and press against and bend the nozzle 18 to close its bore as shown in Fig. 1.

f not for the provision of said nozzle with its thickened root end, as the bladder wall collapses and folds over the rigid air inlet 41, it might be extruded therethrough with resultant puncturing of the bladder and consequent failure of the device. By the bending of the nozzle as previously described and the interposition of such thicker nozzle between the thinner bladder wall and the casing the possibility of such extrusion and hence of such puncturing is prevented. The base disc of fitting 35 and the associated annular flange 37 also prevent extrusion of the nozzle by supporting the entire root end of the nozzle.

With the above relatively simple construction, a highly efficient bladder is provided which is not likely to puncture as the result of extrusion thereof through the rigid air inlet regardless of the amount of oil forced into the container to compress the air in the bladder and, in addition, with the same construction, substantially all bleeding of air from the bladder which might cause failure of the unit due to a defective valve controlling the air inlet is eliminated and this without need for a Schrader type valve or of any additional mechanical valves or the like.

As many changes could be made in the above construction, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claim, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

As an article of manufacture, a deformable bladder having a thickened wall portion at one end having a substantially cylindrical recess therein, said recess having an annular laterally extending groove adjacent the floor thereof, an inlet nozzle of deformable resilient material extending into said bladder and having its root end intcgral with said thickened wall portion, said nozzle having a bore therethrough of relatively small diameter as compared to the diameter of said cylindrical recess in the thickened wall portion, said bore extending through the iioor of said recess and affording communication from the interior of said bladder to the exterior thereof, a tubular tting having an annular laterally extending ange at its inner end positioned in said annular groove, said inner end of the fitting having a floor with an opening therethrough of relatively small diameter as compared t to the inner diameter of the tubular fitting and aligned with the bore in said nozzle.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,343 Mercier et al. Feb. 20, 1951 670,725 Pickett Mar. 26, 1901 1,008,641 Gregory Nov. 14, 1911 2,233,096 Goldsmith Feb. 25, 1941 2,572,308 Brown Oct. 22, 1951 FOREIGN PATENTS 571,874 Germany Mar. 6, 1932