US1937149A - Hydropneumatic accumulator - Google Patents

Description

NOV. 28, 1933. HOLVECK 1,937,149

HYDROPNEUMATIC ACCUMULATOR Filed June 20, 1931 Patented Nov. 28, 1933 TUNITED STATES,

This invention relates to hydro-pneumatic accumulators such as are employed with hydraulic 7 pumps, and also to a method of establishing the desired pneumatic pressure within such anaccumulator. 1.

An object of the invention is-to produce an improved hydro-pneumatic accumulator.

A further object is to produce an improved method of charging such an accumulator with the desired degree of pneumatic pressure.

These and other objects which will be made more apparent throughout the further description of the invention, are attained by means of the apparatus herein illustrated and described.

In the drawing Figure 1 is a diagrammatic view of a hydraulic pump associated with a two-compartment hydro-pneumatic accumulator embodying my invention; and Fig. 2 is a fragmental sectional view illustrating, more or less diagrammaticaly, a detail of construction of the tank shown in Fig. 1. Y

The accumulator illustratedc'onsi'sts'essentially of a two-part accumulator so arranged that both parts maybe employed as a single compartment accumulator, or so that-onepart may be employed in connection with a hydraulic pump in charging the other pressure. v v Hydro-pneumatic accumulatorsordinarily consist of an airtight tank enclosing a single compartment andhaving a liquid inlet port at the lower endthereof, which isconnected to a source of liquid underpressure, such as a hydraulic pump,'and also to a delivery or distribution system for such liquid. The accumulator receives and stores what may be termed a reserve supply of liquid and the arrangement is ordinarily such that air 'is trapped within the-upper portion of the tank and, by being compressed, exerts pres- 40 sure on the liquid within the tank and thereby establishes what may be termed an artificial or a pneumatic head for the'liquid; 3 Accumulators,

such as described, are included as a, partof a liquid-distribution system, where it is desired to with the desired pneumatic sure; A'separate-air compressor is ordinarily employed for initially, and thereafter periodically "charging the accumulator with compressed air so as'to maintain the desired quantity of compressed air and the desired volume of liquid stored within the accumulator. Such compressors, although adding materiallyto'the' cost of an' accumulator installation; are of relatively low capacity and cmnsequently considerable time is expended'in charging the accumulator with pneumaintain the liquid in the system under high pres? matic pressure, hereinafter termed compressed air or air pressure.

Under normal operating conditions it is usuau necessary to periodically recharge the :accumulator with compressed air in orderto re-establish 3b the desired proportionsbetween the quantity of compressed air and the quantity of liquid within the accumulator. 1 his recharging must be re- 7 sortedto every several days, depending, of course, upon the conditions encountered, but the function I of the air compressor, although important, is not such as to merit the additional expense ofa'high capacity compressor. i

The arrangement of accumulator illustrated is such as to eliminate the necessity of employing 7 a separate air compressor during the operation of initially charging the accumulator with compres sedair or. insubsequent. operations of reestablishing the :desired proportionjof air and liquid within-the accumulator. This is accom- I plished by employing a two-p'artor two compartmentaccumulator in which the" arrangement is such that-one compartment may, efiect,

be employed as an air compressor for-charging the other compartment with compressedair at a,

predetermined pressure and maylalso be employed' as the liquid supply chamber and a portion of' the airchamber of the accumulator when the accumulator is used as ,a hydro-pneumatic accumulator.

As shown, the accumulator consists of a shell or tank 4, the interior, of which is divided into what may be termed a primary compartment .5

and a secondary compartment 6 by, an inter- ,7

mediate diaphragm or partition '7. The 'pri- '0 rnary compartment. is provided at its lowerend with a liquid'inlet port 7', which communicates through pipingB with the delivery mama ofthe, distribution 'systemQ As shown, the piping}! is provided with a brancho'pipe 8, whichleadsto an atmospheric discharge and'is provided with a valve 8. Themain 9 receives liquid, hereinafter termed Water, from a pump. 10. The pump may be of any type, but as diagrammatically illus trated, is a multiple cylinder, single acting pum and is operatively connected to a driving motor 11. Water from any source is delivered tofthe suction port 12,0f the pump-and is .=delivered through the discharge L port [13 1 to the delivery main 9.; As is usua1, a'ch'eck valve 14is interposed in the main 9 between the pumpi'and thedistribution system, but it prevents a'flow mule- I 1 L r-.114 f I q -4 to deliver waterv to the compartment 5, the valve The water is then drained from the compartment 5 by opening the valve 8 17 is retained closed.

During this draining operation the valve 'f-. is left open, since under such conditions, the drain- ,ing operation will be augmented by .the air'pressure delivered to the compartment 5 through the check valve 15'. It is, of course, apparentthat the check valve 16' is held closed by the increased pressure of the air within the compartment 6. V

above described, exceptundersuch circumstances that the initial pressurev in the; compartment fi Afterthe drainingof the compartment 5 1's completed, the valve 8" is closed and airunder pressure frompipe 15 is permitted 50.1111 that compartment. The valve 9' is retained in the closed position. The pump 10 is then loaded or caused to deliver water under pressure to the compartment 5 with the result that theair in that compartment will be again displaced and forced into the compartment 6 through the one way, or check valve 16. When thecompartment 5 is completely filled with liquid the pumping operationis stopped, the valve 8" is opened and the procedure above described is continued untilthe desired air pressure is obtained within the compartment 6. I j

At the end of the operation just described it will be apparent that threevolumes of air, initially at 100 pounds pressure, have-been forced into the compartment 6, and that therefore the pressure in that compartment attheLendof the operation has been raised to 300'pounds.

At the end of the twelfth air displacing operation the pressure in the compartment 6 will equal 1300 pounds per square inch. T In order to obtain the desired normal operating pressure within the combined compartments 5 and 6 I then operate the pump 10 to fill the compartment- 5 to the normal water level,'suchas'indicatedin Fig. 1 by the dotted line X, it being understood that preceding this operation the compartment 5 .was first filled with air at 100 pounds pressure. I then close the-valve 15." and by opening the valve 17 connect the two compartments 5 and 6, and with the volumetric capacities of a tank such, 'as illustrated, the resulting pressure within the accumulator willequal 1000 pounds pressure. {It

is, of course, apparent that the predetermined pressure to which the air is raised .within' the compartment 6 will be, established by thevolumetric capacities of the.,twocompartments jarid the volumeof the compartment 5 Which'is to be employed as a part of the combined air chamber.-

This is merely a matter of mathematical computation. a

After the accumulator is thus initially charged with air, the valve 9' is opened, the loading and unloading mechanism is rendered automatic and, in the example given, the pressure gauge 18 will record 1000 pounds pressure and will therefore unload the pump; The pump 'will remain-un- T loaded until delivery conditions, lower the level of the water within thecompartment 6 to a level, such as indicated by the dotted line Y in Fig. 1, at whichtime the pressure within the accumulator will have dropped a sufiicient amountto actuate the automatic mechanism to load the pump and to deliver water at the pumped pressure to the accumulator.

It will be apparent that to those skilled in the I art that the passage '17 and valve 17"may be. replaced by any means for establishing communication between the compartments 5 and 6 after the charging operation is completed. For example, the passage 17 and valve 17' may be omitted by providing means for opening the check valve level of the liquid to the top of the compartment 5, thus forcing the compressed air from compartment 5 into compartment fi. The valve 17f is then the draining operation the valve 8 is closed andair at'l00 pounds pressure fills the compartment as the compartment 5, is lined with .water the pressure of the air. above the water is increased,

check valves 16 and-15' respectively, and the by so doing ,I may providega more adequate pas sage between the two compartmentsthan would be possible, or atleast otherwise, desirable.

. If, during normal operation, the quantity-of airin the accumulator is reducedthe recharging operation iscarried on inthe same manner as is materially abovethepressure available the air piping 15 A loss of air will be noted byithe Water level within the icompartment 5 whenthe: pressure in the accumulator is raised to thenormal operating pressure 1000 pounds) That I is to say, if the water level in the compartment-5- is 9' is closed and the-pump is operated. to raise the closed, thus trapping the highpressure air in compartment 6. The valve 15" and the valve 8" arelthen opened to drain compartment 5. After 5. The pump is then operatedto .again 'fill cornpartment 5 with water. It will. be apparent that and at some ater. levelthe pressure of the'air "in. compartment 5, vvvill exceed the "pressure .trapped within the compartment Grand conse-. .q'uently air from compartment 5 will be delivered through theone-wayvalve 16. to'the, compart ment 6 as the Water filling eperationis continued. [The rechargingjoperationjis thereafter similar to the charging operation andwhen' the desired pressure is again obtainedwithinme compartment 6, the valves 8'1 and.15'.5 closed,.th'e valves9 and '17 are openedand the .switch 21 is permanently closed, with the result, that the 'appa'ratusis again in condition for nor- }mal operation and under' the automatic control of the loading and unloading mechanism '1 Y i 125 i It Will ,.0f course, be'apparent that the operation of initially charging the accumulatorfwill" I be somewhat lengthened if a pressure lower-than IOO-p un ds pressure is initially: admitted to the compartmentsS and 6, but that the charging and g l the recharging operations may be accomplished even though air under pressure is not available. Under such conditions air at atmospheric pressure is trapped in the compartments 5 and- 6 by the,

valve 1'7 is then closed. The further oper'ation'of 5 must be more'carefully observed.- .That is to 143 say, the water must be raised to themaximum level in the compartment 5 during each air displacing operation, since otherwise the operation of charging or recharging will be greatly lengthened. l

While I have described what I now consider to bathe preferred embodiment of my invention, it will be apparent that omissions, other than those mentioned, and other variations in the apparatus illustrated may be made without depart-f are permanently charging or recharging will be asabove described,

ondary compartments of the" accumulator, a

check valve communicating with theupper por- 1 tion-of the primary and with-the secondary compartment for delivering fluid under pressure i from the primaryto the secondary compartment, means for establishing communication between said compartments to-deliver fluid from the secondary to'the primary compartment, means for delivering liquid under pressure to the primary compartment; means for'draining the primary compartment, and means for connecting the 1 lower-portion of-the primary compartment to" a liquid distribution system; I 7,

2. A combinedhydro-pneumatic accumulator and "chargingmechanism comprising a storage chamber for 'compressible fiuids, a compressor chamber, a source of supply of compressible fluid underpressure, branch pipes connecting the source of supplyof fluid with'the storage and compressor chambers, respectively, a check valve between the supply source and the branchpipes and a check valve in the branch pipe communh catingf with the storage chamber permitting flow of-fiuid from the compressor chamber to the storage-"chamber, a drain for the compressor 'chamberpa source of pumped liquid means for alternately connecting the'bottom of said compressor chambertothe source of pumped liquid and to thedrain, whereby when the compressor "chamber is connected to drain, fluid enters the 'same'to'replace the liquid and when the compressor chamber is connected to the supply of 1 pumped liquid, the fluidis compressed and de-- livered' to the storage chamber; and retained therein by the check valve in the ,branch'pipe connected. thereto, and"means for connecting j the storagechamber with the branch pipe conn'ecting the compressor chamber when the pressure in the storage chamber is of a desired preunder pressure, branch pipes connecting the "source of supply of fluid with thestorage and determined value and the compressor chamber :is-charged with liquid to a predetermined level.

3'. A combined hydro-pneumatic accumulator .and charging mechanism comprising a storage chamber forcompressible fluid, a compressor chamber,iasource of supply of compressible fluid compressor chambers, respectively; a check valve between the supply source and the' branch pipes ice 1 ages-m g and acheckvalve in the "branch pipe connecting the source to f thestorage chamber-permitting the flow of fluid from the compressor chamber to the storage chamber, a drain" forthe compress'or chamber, asourceof pumped liquid and liquid distribution system, means adapted to alternately connect the bottom of said compressor chamber to the source of pumped'liquid and 5 to drain, *whereby when the compressor chamber is connectedto the drain, fluid enters the'same to replac'e'the liquid and whenthe com- 'pressor chamber is connectedto the supply of pumped liquid, ,thefluid is compressed and deiivered to the storage chamber and retained therein'by the check valve in the'branch pipe connected thereto, a pipe having avalve therein .forinterconnecting said chambers in fluid ex- "changingrelation independently of the check valve in said branch pipe when" the pressure in the storage chamber isof a desired predetermined value and the compressor chamberis charged with liquid to a predetermined'level, andmeans i for connecting the compressor chamber: to'the source of pumpedliquid and to the distribution system so that both chambers function as an accumulator. I

4; A combined"hydro-pneumatic accumulator Fahd-selfcha r g ingidevice comprising two independent compartments, a "source 'of supply of compressed fluid, branch pipes connecting said compartments toth'e-source, a check valve between the source and branch pipes, a check valve an hydraulic pump and a distribution line there- 'for 'means' adapted to alternately "connect the other of" saidcompartrnents to the drain and to the distribution line, of the hydraulic pump,

initial1yfi1led with compressed fluid at thepressure of the source,"and when said last mentioned compartment is connected to the "distribution line'liquid is delivered thereto to compress the I in one ofisaid branch pipes connected to one or" 7 said: compartments permitting .the flow of fluid "thereto from the other'compartmentp adrain,

fiuid thereiniiand deliverit :to the other. com

partment wherein the fluid isretained by the connecting said compartments in free fluid" exchanging 5 11318111011 when the level of theliquid predetermined height andthe pressure in the JOSEPH E. HOLVECK;

check valve in said branch pipe, and means for

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