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Publication numberUS1931029 A
Publication typeGrant
Publication dateOct 17, 1933
Filing dateSep 29, 1930
Priority dateSep 29, 1930
Publication numberUS 1931029 A, US 1931029A, US-A-1931029, US1931029 A, US1931029A
InventorsFrank Mcfarland
Original AssigneeFrank Mcfarland
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Alleviator for hydraulic apparatus
US 1931029 A
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Description  (OCR text may contain errors)

Oct. 17, 1933. F. MCFARLAND ALLEVIATOR Foa HYDRAULIC APPARATUS- Filed Sept. 29, 1930 /A/ VEA/Toe: Fen/vr M-CFA @Ln/vp.

Patented Oct. 17,1933


- :Application september 29,1930 5 l i seria11No.4s5,124 f 1 1 claim. "write-42.23;); "L

This invention relates to*alleviators'or hy dfall Pumps,l flowumes and other kindsfof hydraulic apparatus, l

V"Iv'he main object of my inventionistopro `5ivide a compact and inexpensive,alleviatorthat isparticularly adapted for use with large sized pumps and with large'sized mains in` which a considerable volume of liquid isbeingl pumped. f Another object is toj provideV a multi-'cylinde'r -alleviator `i`n which a single'pisto'n *or plunger that is arranged in opposed lrelationship with` n A on the lowery endof the'pistonV is'agasket' 2bv an expansiblemeans or a shock absorbing me# dium confined in one cylinder, also acts as a valve or cut olf device `to control the admission 1'5 `of the pumped liquid to a second or separate cylinder wherein is confined ameans or medium that co-acts with the pumped liquid to absorb shocks.

I have herein illustrated my present invention 2`0`Iembodied in an alleviator of the general type Y disclosed in my U. S. Patent No. 1,640,046, dated August 23, 1927, but I wish it to be understood that my broad idea is applicable to various types and kinds o alleviators and thatvarious changes may be made in the constructionand arrangement of the parts or" the alleviator without departing from the spirit of my invention;

Figure 1 of the drawing is a top plan view of a hydraulic pump equipped with an alleviator yimembodying my present invention; and

Figure 2 is an enlarged Vertical sectional view of said alleviator.

In the drawing, A designatesa conventional hydraulic pump that is usedl for forcing a liquidthrough a main or ilow line, and vB designates as an entirety an alleviator for reducing the force of discharge of the liquid being pumped or for maintaining a substantiallyV uniform rate of discharge of liquid from Aor through the ap- 40 Jparatus with which the alleviator is used. In Figure 1 the alleviator B is illustrated as being mounted upon or connected with the discharge pipe l of the pump, but it will, of course, be obvious that the alleviator may be arranged in 4,5.A lvarious other positions. j l

The alleviator B comprises a cylinder C closed at its upper end and provided at its lower end with an opening 2 that establishescommunica tion between the interior of the cylinder and the =.'clischarge pipe l of the pump, and a` reciprocatin? piston or plunger D is mounted in the cylinder C in such a manner that when a certain approximate pressure develops in the discharge pipe 1, the piston D will move upwardly Yand 5'5 compress a shock absorbing means in the upper portion vofmthe cylinder C which will usually con?. sist of 'anjexpansible medium'such ascompressed air, vor compressedair and ra bodyl of`oil"'.'1:jor

other suitable liquidthatseals the joint between the Asidewall ofl the cylinder C andthe coasting side wall portion ofthepiston D. "At tlfrelower end ofthe piston D 'is a reducedvextension 2&1" that constitutesa dash pot element which enters the opening" 2 in'thelowerfendfof lthecyli'nderV as 'the pistonfD 'nears' the end of its downward.v stroke. fsurrounding the vclash pot element-'23" thatV effectively seals the lower end of* the cylin`` der C when the piston D is at the end of its downward stroke. v

The alleviator B also comprises an additional cylinder or second cylinder E whose upper end is closed and whose lower end is connected by a lateral outlet 3 with the cylinder` C adjacent the lowerend or open end of the cylinder C. When the piston Dis in its depressed position, shown in Figure 1, it acts asa Valve for the lateral out let 3 that absolutely cutsloff communication between the interior of the cylinder E and the interior of the cylinder C or the pipe 1 through which the pumped liquid is flowing. When the piston D moves upwardly, due to the pressure exerted on same by the pumped liquid, said pumped liquid can enter the lateral outlet 3 leading to the cylinderE.

Thecylinder E is provided with a means or medium for absorbing the rshock produced by the inrush of the pumped liquid into the cylinder E. Various meansrmay be used for this pur` pose, but I prefer to charge the cylinder E with compressed air or a similar medium` that is capable of being compressed by the pressure exerted on same by the inrushing pumped liquid and thereafter expanding after the shock has been absorbed so as to eiect the discharge of the liquid from the cylinder E. In order to facilitate the introduction of the expansible shock absorbing medium into the cylinder E, a


from same, due, of course, to theV fact that the combined inlet and outlet 3 of the cylinder E is closed tightly by the piston D which acts as a valve or cut-off device. In practice some of the pumped liquid that enters the cylinder E when the piston D moves upwardly, remains in the lateral outlet 3 when said pistonreturns to its depressed position,4 and this body of liquid that becomes trapped in the lower portion ofthe cylinder E or in the connection 3 betweenv the two cylinders serves as a liquid seal for the piston D that absolutely eliminates the possi` bility of the expansible medium in the cylinder E' escaping from same. I prefer to design the alleviator so that the main force of the shock is taken up by the expansible medium conned' in the cylinder E, and accordingly, I propose. tov

charge the cylinder E with compressed air. whose initial pressure is -less than the pressure. of the air conned in the upper portion of the cylinder'v Onefof the main advantages of my improved` alleviator is that it may be designed for use with. large sized pumps and withV large sized mains in which a considerable volume of liquid is being pumped, without producing a cumbersome andy expensive structure, as would be liable to result if the alleviator .wereY provided with a single cylinder containing a yshock absorbing means or medium. v*Another very desirable characteristic of my improved alleviator is that it is practically impossible for an expansible medium confined in the cylinder E to escape therefrom, 'if the alleviator remains inactive for a long period, thereby insuring that the alleviator will always be in readiness to act and perform the function forY which,y it is designed.. y n

Y Having thus described my invention, what I claim as new and desire to secure by Letters.

a. gas that isfundersuilicient super-atmosphericA pressure to constitute afshocl-absorbing medium for the pumped liquid, and a connection between said primary cylinder andA secondary cylinder arrangedY so that after the plunger in the primary cylinder has. been moved by the pressurevof the pumped liquid, said liquid will thereafterfv enter the secondary cylinder, 'whereby the shock will be absorbed progressively by the cornoint action of said primary cylinder and secondary cylinder;-


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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4972879 *Apr 7, 1989Nov 27, 1990Toshiba Kikai Kabushiki KaishaSurge-pressure removing system for back-pressure in injection cylinder
U.S. Classification138/31
International ClassificationF04B11/00
Cooperative ClassificationF04B11/0016
European ClassificationF04B11/00A2