US2334708A - Hydropneumatic device - Google Patents

Description

Nov. 23, 1943. .J. F. JOY

HY'DROPNEUMATIC DEVICE 2 Sheets-Sheet 1 Filed March 23, 1942 3,,WW h fly WW 7% MM rinse Patented Nov. 23, 1943 9 Claims.

(Granted under amended April 30, 1928; 370 0. G.

Y The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention pertains to a hydro-pneumatic device and more particularly to an equilibrator and a bellows member for use in conjunction therewith.

An object of the invention is to provide a hy dro-pneumatic spring of the expansion bellows t e.

jmother object of the invention is to provide an elastic bag which is adapted for use in a hydropneumatic device.

A further object of the invention is to provide a flexible extensible bag of elastic material which collapses into a compact, substantially solid mass.

extended position, the bellows being illustrated in side elevation,

Figure 2 is an enlarged axial sectional view of the right hand or hydraulic end of the equilibrator shown in Fig. l,

Figure- 2a is a smilar view of the left hand end which includes the gas chamber of the device,

Figure 3 is an axial sectional view of a portion of the device in a retracted position,

Figure 4 is a transverse sectional view on the line 4-4 of Fig. 21].,

Figures 5 and 6 are respectively end and side views of one of the disks employed in making the bellows,

Figure 7 is an end view of the opposite side of the disk of Fig. 5, I

Figure 8 is a diagrammatic axial sectional view representing the manner in whichthe disks are assembled to form a bellows.

Figure 9 is a similar view showing the method of assembling a modified bellows,

Figure 10 is a perspective view, with a portion removed, of the outer metal grommet employed in the structure represented in Fig. 9, and

Figure 11 is a perspective view of the inner metal grommet used in the bellows illustrated in Fig. 9.

Referring to the drawings, a gas cylinderl is provided with an end closure 2 having a coupling member 3 which enables the cylinder, to be secured to a device which is to be balanced. A pasthe act of March 3, 1883,as

sage 4 in the closure 2 permits the admission-of gas which is retained in the cylinderby suitable means such as a valve 5. The oppositeend of the cylinder is sealed by a head or closure 6 which has a threaded, centrally disposed bore 1 which supports a hollow piston rod 8v that projects, to the right. 8 is provided with an enlargement which forms a piston 9. Packing material I0 is confined in an annular space H on the periphery of the pistonby suitable means such as ring l2. The right hand end of piston rod 8 adjacent the piston is conditioned with a .plurality of ports 13 which permit the circulation of fluid in .a manner which will be subsequently mentioned. Encompassing the piston 9 and slidable thereon inv fiuidtight relationship is a cylinder M which issealed at its right hand end by a closure 15. A coupling member 16 serves as the means for, attachment to a device which is-to be sustained elastically. The inner end of, cylinder M is provided with a substantially bell-shaped cap I! which is slidable on the piston rod 8 and is maintained in fluidtight relationship therewith by a packing glandwl 8-I8. A dust sleeve l9 encloses the. piston rod 8 and is detachably mounted on a skirt 20 extending from head 6. .A valve 2| in the cap I! permits the introduction of oil into the cylinder l4.

As shown in Figures 1, 2a, and 3, the open end 22 of an extensible bellows 23 is fastened to the fixed head 6 on the gas cylinder I by means of a clamping ring 24, The open end 22 surrounds the bore 1 in the head 6. Spaced set screws 25 secure the ring to the head with sufficient pressure to create a leak-proof seal. The bellows comprises a series of interconnected annular disks 26 of thermoreactive elastic material such as rubber or a synthetic rubber-like product. These are bonded together by means of heat and pressure at alternate inner and outer edges so as to form a bladder having a plurality of convolutions 26 (Figure 1), which, when extended and viewed in axial section, appears as delineated in Fig. 2a. The movable end 21 of the bellows is clamped between the enlarged head 28 of an elongated guide rod 29 and a disk or guide plate 30 by a nut fastener 3|. The guide rod is arranged to reciprocate in the hollow piston rod 8 and is preferably provided with longitudinal flutes 32 to facilitate the passage of oil into the bellows. The enlargedhead 28 is also fluted and is tapered at 33 to allow it to seat in the head 6 near the end of the hollow piston rod 8 when the bellows is collapsed as shown in Figure 3. The guide rod 29 promotes aligned longitudinal expansion of the The projecting end of the piston rod which later can be dissolved in a suitable solvent bellows and increases the life of the bellows by avoiding wear due to rubbing against the inner wall 01' the cylinder.

In the ordinary use 01' the equilibrator the coupling members 3 and It will be connected to parts 01' the mechanism to be balanced in such a way that the unbalanced weight will tend to extend the equilibrator to a position similar to that shown in Fig. 1. Oil or similar fluid is then introduced into the cylinder H in a sufilcient quantity to fill all spaces inside 01' and to the right or the expansion bellows whereby the system is purged of imprisoned air. Gas is then introduced through the valve linto thecylinder I in a sumcient quantity to support the weight to be baianced. In this balanced condition the mechanism can obviously be shifted in either direction with a minimum expenditure of energy. As the load is moved in a direction tending to extendthe equilibrator, oil will be displaced through the ports l3 in the hollow piston rod to extend the bellows member 23 against the pressure or the compressed gas.

It will be obvious that the equilibrator'might also be used in any application requiring a spring suspension, in which case the load should be connected thereto in such a manner as 'to tend to extend the equilibrator on increase in load. In such an application a load 01 any magnitude may beelastically suspended by the proper choice of the gas pressure in the cylinder I. In this use of the equilibrator as a hydro-pneumatic spring it may be desirable to select the size of the ports l3 in the piston rod 3 so that a throttling action will occur at these ports or orifices whereby a shock absorbing effect will result.

When the equilibrator is telescoped into its shortest length as shown in Fig. 3, the bellows 23 is collapsed into a substantially solid block and is resiliently sustained in this form by the action of gas under pressure. Both gas and oil are effectively squeezed out 01 the annular interstices between convolutions of the bladder. Since gas tends to permeate the bellows and aerate the fiuid compartment at all times, particularly when the device is in an elongated position, the opportunity to do so is materially reduced or avoided when the bellows is collapsed. -The block-like configuration oi the bellows increases many times the ordinary thickness of the elastic wall through which the gas must penetrate to mix with the oil and hence a material resistance to such infiltration is presented. The block-shape characteristic of the collapsed bellows has an additional feature in that a high gas pressure will not tend to invert or force the bladder through the opening in the cylinder head 6.

Figures 5-7 illustrate the type of disk employed in fabricating a bellows of the character described and Fig. 8 represents diagrammatically one manner in which a plurality 01 these disks may be assembled. In the formation of a right cylindrical bellows, thin circular disks 26 of uncured rubber having a centrally disposed aperture 34 are used. The opposite faces 01' each disk are conditioned prior to stacking. Fig. 5 represents the right hand face of a disk and has an annular inner border designated generally as A which is to be bonded to a similar area on an adjoining disk. If desired, these areas may be treated with a cement to insure a bond. The outer space designated as B will not be bonded to the corresponding space on a contiguous disk. Hence it is conditioned with an anti-stick material which may be in the form of a thin annular disk 33 (Fig. 8)

without injuring the completed bellows. Pig. 7 illustrates the right hand side of the disk 33 and the disposition of its active and non-active areas,

C and D, respectively. In the stacking operation,-

active border areas C of the adjoining first and second disks are superimposed incontiguous relationship and an anti-stick spacer 33 is inserted between these disks and against their respective D areas. The third disk is stacked so that its active A area adjoins the corresponding A surface on the preceding or second disk and an antistick spacer 35 masks the inactive 13 areas. This procedure continues until a stack of the desired longitudinal dimension is attained. The stack .is then placed in a mold unit whereupon heat and pressure are applied. Rressure is exerted parallel to the axis of the bellows on the C and idle A areas to bond the laminated structure in these zones. This produces a bellows oi the character illustrated in conjunction with the equilibrator. Since the anti-stick disks are unaflected by heat and pressure, they may be dissolved after the vulcanizing operation.

Figure 9 illustrates a portion of a bellows provided with annular metal reinforcements which is manufactured in a manner similar to the be]- lows previously described. A series of metal grommets 31 are arranged so that each grommet engages the internal edges Of a pair of disks. Annular metal grommets 38 engage the outer edge so that the disks are interconnected as an accordion-like extensible unit. Pressure may then be applied to the end grommets parallel to the bellows axis to bind the assembly together in 'a fiuidtight relationship at the desired areas. This provides a sturdy bellows sinceit is less subject to tearing at the bond zones and provides an organization with a bore of small diameter where such is desirable.

I claim:

i. In a hydro-pneumatic device, a, chamber containing a gas, an expansible member in the chamber in fiuidtight relationship with the gas therein, a tubular member protruding from the chamber in communication with one side of the expansible member, a piston on the protruding end of the tubular member and sealing the end thereof, a chamber containing a liquid recipromember, said tubular member having an orifice therein adjacent the piston whereby liquid in the reciprocable chamber is displaceable in the expansible member upon movement 01' the reciprocable chamber relative to the piston.

2 In a hydro-pneumatic device, a gas cylinder, expansible means sealing the cylinder, a tubular member protruding from the cylinder and communicating with one side of the expansible means, 'a piston on the protruding end of the tubular member, a liquid cylinder slidably mounted on the piston, and an orifice whereby liquid in the last namedcylinder is displaceable in the expansible member.

3. In a hydro-pneumatic device, a cylinder containing gas, an expansible means sealing one end of the cylinder, a tubular member protruding from the cylinder and communicating with a side oi! the expansible means, a piston on the protruding end of the tubular member, a cylinder containing liquid reciprocably mounted about the piston and the tubular member, said tubular member having an orifice therein adjacent the piston, and guide means secured to the expansible means and slidable in the tubular member.

cably mounted about the piston and the tubular 4. The structure as described in claim 3 wherein the guide means secured to the expansible means comprises a fluted rod having a, close sliding fit with the tubular member.

5. The structure as described in claim 3 in cluding means on the cylinders for attachment to a device to be balanced.

6. In a hydro-pneumatic device, a cylinder containing gas, an extensible bellows secured at one end within the cylinder and sealing an end thereof, a tubular member protruding from the cylinder and communicating with the interior of the bellows, a piston the tubular member, a cylinder containing liquid reeiprocably mounted about the piston and the tubular member, said tubular member having at least one aperture therein closely adjacent the piston, and a fluted guide rod secured to the free end of the extensible bellows and slidable in the tubular member. 7

'7. In a hydro-pneumatic device, a cylinder containing a gas, a head at one end including a coupling means, a head at the opposite end thereof having an aperture therein, an extensible bellows in the cylinder secured at one of its ends to the head and about the aperture therein, a projecting tubular member secured within the aperture and communicating with the interior of the bellows, a fluted guide rod secured to the free end of the bellows and extending into the tubular member in sliding relationship, a piston on the projecting end of the tubular member and sealing the end thereof, a cylinder containing a liquid reciprocably mounted about the piston and the tubular member, a head having a coupling means on one end of the cylinder, and a head including a packing gland at the other end of the cylinder fitted about the tubular member, said tubular member having at least one orifice therein closely adjacent the piston whereby liquid in the reciprocable cylinder is displaceable into the extensible bellows against the resistance of gas upon movement of the reciprocable cylinder relative to the piston.

8. In a bellows, a plurality of annular discs of elastic material interconnected on alternate inner and outer edges in fluid tight relationship, said discs adapted to form a hollow, substantially block-like member when collapsed and a generally thin walled bladder when elongated, and a rod extending centrally through the bellows and connected to one end thereof, said rod being provided with fluid passages.

9. A bellows as in claim 8,wherein the rod at the end of the bellows is provided with a disc outside the bellows and of the same diameter as the bellows discs.

JOSEPH F. JOY.

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