Sept. 24, 1946., > ' I _ >w_ ERNST 2,408,303 cONTROL SYSTEM ' Filled May 10, 1945 .lj-l. ,5 ~ Ill/ll/l/l/I 121-3- ~ III/Ill 26 INVENTOR WALTER ERNST, BY ‘ . ‘vW -_ ATTORNEYS . 2,408,303 Patented Sept. 24, 1946 ' UNITED‘ \ STATES ' PATENT ' l . " _ ' I V . v V ' I vOFFICE ; ».2,-4os,s0s cQn'rRoL SYSTEM. Walter :‘Ernst, Mount; Gilead, Ohio, assignor. to The ‘Hydraulic ‘Development Corporation, Inc", Wilmington, Del.,, a corporation of Delaware Application'May 10, 1943, SerialNo. 4861,1283: 4--Claims. (Cl. 60—52‘) ' 2. restriction. Both. sides of the ?uid ?ow restric tion are connected with two opposed substantially equal areas of a '?uid operable control plunger adapted whenmoving to vary the delivery'of» the ‘This invention ‘relates to hydraulic systems andyin particular, to hydraulic control systems including’ a ?uid-‘pressuresource of. the variable deliverygtype. ‘ ‘ ‘ ?uid source, Therefore, any'substantial varia I-t-is an object’ of-Ithis'?invention ‘tolprovidea hydraulic system which vincludes areciprocable tion in the pressure drop across. the fluid, ?ow plunger and a pressure '?ui'dsourc'e of variable . restriction will cause‘thev control plunger to vary delivery.‘ for: supplying; pressure-?uid to said the delivery ofrrsaid ?uid‘source in such a man ner that the initial pressure drop is-restored. plunger, ‘and in which vthe-delivery of the pres sure-‘fluid sourcez-tosaid plunger 'islcontroll'ed-gaue 10 Structural arrangement" tomatica'l-ly response to. the-resistance encoun tered-'ibylsaidmotor. .- a’ r 1 ' ~ ' '7 . } Referring novv'tothe drawing. andto Figure-i ' ' It'lis anotherobj'ect' to=provide a hydraulic sys thereof‘ in. particular, the.’ system shown there tem including a, i?uid operable 'plungereactuated by a pressure<i-‘lu-idlv source ‘of-variable delivery, in which a1 ?uid ?ow? "restriction .is interposed be in comprises a cylinder I having 'reciprocably mounted therein: a plunger 2 with an advancing area 3 and a retraction area 4, Connected to-one end of thecy-linder l is a conduit 5 comprising a preferably adjustable choke 6 and leading toa tween the-?uidrsource- and ‘the plunger,v and‘v in which the.v delivery oilwthel i?uid source is auto; conduit 1. 'Oneend 0f.- the». conduit ‘Iv communi matically controlled so i as. -t'o=-hold1' the; pressure drop. across; said» --restriction-- substantially vcon 20 cates vwith a conduit-8 comprising alcheck Valve 9 and communicating-withtheconduit5;; 'Ilhe conduit‘ 8 furthermore communicates with a stant during the working stroke of. said. plunger. It is-a. further object to provide: a hydraulic systenrincluding fa. pressure ?uid Source-of." vari‘ four-way valve ' l 0 ‘of any- standard- design-adapt. ed, whenin one. extreme position, to effect ?uid from.-.said; ?uidzsouree, ‘in .which: ag?uid’: ?ovv re 25 communication between the pressure line »'_:H I and‘ the line 8 ‘while simultaneously connecting the striction. is- interposediabetween, ‘said; ?uid. source conduit. I2, communicatingv with the retraction and.;said plunger and .ishydraulically:wnn'ected ableadelivery‘ and-;.-a plunger operable by-?uiid side of the plunger 2, with-the-.exhaustylinelQ with control plunger. meansvarying the delivery of said ?uid sourcein response to variations in leading to a ?uid-reservoir or tank [4; When the valve?lroccupies its other extreme position ?uid = the. pressuredropaacrosssaid restriction.» - > These; and- other objle‘ctslandlad'viaritages éinthe communication is established between themes: invention will‘ appear-more-= clearly Lfrom the Ilfol- ' sure-z line H and the conduit t2, while-‘simulta neously the conduit: I3 is connected with .the cone duit 8. When the. valve t0 occupies-its interme diate or center position, no ?uid passes‘; through the valve. The check valve 9 in the conduit ?-is sofarranged as to permit the?ow oi-i?u-id-there through: from’ the. conduit .= 5 to the~¢four-way: valve l0, while preventing: the ?ow- of ?uid in the re lowing; speci?cation in connection. with: i-thev~lac= companying drawing, in which : - Figure 1,:diagrammatica1lyr illustrates a 'hy- . drauliesystem. according to the invention; Figure. 2; shows a hydraulic'system for. con trnlling'a differentialiplunger .in..:bo'th directions. Figure. an a diagrammatic illustration lot-a further: ‘hydraulic . ‘system. according, - to _ ~ the in vention in: whichthe plunger "to I be.’ controlledais double; acting, and has; substantially 2 equal. op llosedareas. ‘ >> I General arrangement The hydraulic: systemziaccord-ingitoathez. invens tion substantially. comprises az?uidxsource of;vari-.-. able "delivel'mgsuch. as a variable delivery pump... and: a,~?uid; operable plungenqwhile: a fluid; now 40, verse direction. The.conduit.’|~'1eads/to a control cylinder. l5‘ having-reciprocably mountedrtherein a plungenl?' of substantially equalopposed areas l1 and-xiii. The'plungery I6 is connected to the .?‘ow control member of a variable‘ delivery. pump: |9wsotliat rightward ‘movement of. the plunger l6:with re gard to Figure. 1 decrease; the delivery of. the pump l9, whereas. leftward vmovement of the. plunger I6 causes a. spring 20in the springxcham-v restriction, , such as a -.choke: valve, __ is; interposed 50 ber 2| vto act upon ‘the ?ow control member; of‘ ‘ between the, delivery; sideot; the fluid,- source and at least the advancing sidev ofythe, plunger tozhe controlled. The arrangement is- rsuchi vthat. the the pump. l9 sons to ‘increase the deliveryof the pump Hi. The spring. 20,, which continuously urges the pump l9 into full delivery position, is adjustable with regard to its thrustby meansof delivery-; ofg. the; fluid. source- to; the ra'dvaneinggside ' of the. plunger [must pass. through‘ the. fluid flow 55 an adjustingscrew. 22, The-spring chamber 2| gasses 3 4 is hydraulically connected through a conduit 23 with the ?uid tank I4. The fluid tank further resistance encountered by the plunger 2 during its advancing movement drops, the plunger 2 will more communicates through a conduit 25 with the suction side of the pump I9 and also corn municates through a conduit 25 with a bore 2% in an extension of the control cylinder I5. This bore serves for guiding the control plunger I6. tend to increase its advancing speed. As a re sult thereof the pressure in the conduit 21 will drop to a greater extent than the pressure'in the conduit 1 so that the pressure acting upon the area U will overcome the pressure acting upon the' areav I8 plus the thrust of the spring 20, and The area I8 of the control plunger I6 is hydraui will move the plunger I6 right'wardly; “This con lically connected through a conduit 2'! with the 10 trol will result in a decrease in the delivery of conduit 5. Opposition It may be assumed that all parts of thesystem shown in Figure l occupy the position in which they appear in the said ?gure. If it is now de~ sired to have the plunger 2 perform a working cycle, the operator shifts the valve In into posi tion for establishing ?uid connection between the pressure line II and the conduit 8 while simul—. taneously connecting the.v conduits I2 and I3 with each other. Provided the pump I9 has been started, pressure ?uid delivered by the-pump I9 will now pass through line II, valve I9, conduits 8, ‘I and 6. From there the pressure ?uid will pass through conduit 5 into the left hand posi tion of the cylinder]. Here it will act upon the advancing area 3 of the plunger 2 and move the '~ - the pump I9 so that the previous ?ow across the choke 6 and thereby the pressure drop across the choke will be restored. Therefore the plung er 2 will again move' at its initial speed, and the control plunger I6 will maintain its position as long as no'further variation in the resistance encountered by the plunger 2 occurs. . When the plunger has reached the end of its working stroke, and it is now desired to reverse 20 the plunger 2, the operator shifts the valve In into position for establishing ?uid connection between the pressure line II and the conduit I2, while latter rightwardly. The ?uid expelled ‘by the plunger 2 from the cylinder I during this right simultaneously connecting theconduitst and I3 with each other. Pressure ?uid deliveredby the pump I9 now passes through conduits II and. I2 into the right hand portion of the cylinder I. Here it acts upon the retraction area 4 of plunger 2, thereby causing the, plunger 2 tomove left wardly. , The ?uid expelled from ‘the left hand ward movement ‘escapes through the conduit vI2, 30 portion of the cylinder I_._during- this leftward the valve I I and the conduit I3 into the tank I4. movement of the plunger 2 escapes through the When the fluid delivered by the pump I9 passes ‘through- the-choke valve 6, a pressure drop will occur across this choke valve‘which pressure drop will make itself felt on the opposed areas IT and conduit 5, check valve 9 and conduits .8 and I3 into the tank I4. It will be noticed that during this retraction stroke the choke 6, is jby-passed .‘ and therefore is ineffective, so that no speed con trol is exerted upon the plunger 2 duringits re: in the conduit ‘I and therefore on the areas I? traction stroke. However, in general, no speed of plunger I6 “Will be greater than thepressure control is necessary during the retraction stroke in the-conduit 21, and therefore upon‘thearea of the plunger 2 since, as a rule, no variations in I8, thevpressure acting on the area I7 Will some What counteract the spring 20 and slightly re 40 resistance occur during the retraction stroke-of the plunger 2. e . ~ duce the delivery of the pump I9 until the pres I8 of the control plunger I6. Since the pressure sure acting on‘ the area I‘! balances the pressure . When it is desired to bring?the plunger 2 to a acting on the area I 8 plus the thrust of the spring 2EI.v ' When this balancing» position has been stop, the valve. I0 is moved-into its neutral posi reachedjthe flow through the-choke valve 6 and thereby the pressure drop‘ created thereby will under‘ ‘normal conditions remain substantially ard servomotor means, which maybe associated with the pump. I9, will cause the pump l9 to shift into substantially neutral or no delivery position. constant, and the plunger 2 will perform its work ing stroke at a substantially constant speed. ~ If it should not occur that, for some reason,-the tion and the pump I9 is either stalled or stand Second embodiment ‘ Referring ‘now to Figure 2, the structure shown therein substantially corresponds’ to, the struc plunger 2 encounters increased resistance,’ this ture of Figure 1 withzthe exception that addition will temporarily slow down the movement of the a1 control means are provided for‘ e?ecting a plunger 2. As a result thereof the pressure in'the speed control also during .the1 retractionstroke lefthand portion of the cylinder I and therefore, also in the conduit 27 will increase to a greater (71 D1. of the plunger. .To'more clearly indicate v.the similarity. between Figures 1 and 2, the elements extent than the pressure in the conduit '1'.’ Con of Figure 2 corresponding to those of Figure 1 sequently the previously mentioned balancing have been designated with the same reference condition will be disturbed, and the plunger it numerals as inFigure 1 however, with the addi will be moved leftwardly until the pressure acting upon the area I'l' will again be balanced-by the 60 tional character-a. The difference between the pressure acting on the area I8 plus the thrust of structure of Figure 2 and the structure of Figure the spring 20. In view. of the thus e?ected left~ 1 consists in that the control mechanism associated with the advancing side of the plunger 2a Ward movement of theplunger E6, the spring 253 is duplicated for the retraction area do. To this vacts upon the control member of thepump ISso as to increase the delivery of the pump~ is. in I end the righthand portion of the ‘cylinder la is view of this increase in the delivery of the pump connected with a conduit 28 comprisinga choke I9, the previous flow across the choke 6 will ‘be 2a ‘and leading to the four-‘way ‘valve? Hid; restored and therefore also the previous pressure Branching off from the conduit 28-is a conduit drop across the choke .6. The plunger 2 will con 30 containing a check valve 3| adapted to~allow sequently resume its previous speed. The control -. plunger I6 will maintain its new position, i. e., hand portion of the cylinder Ia to ‘the check the thus changed delivery of the pump I9 will now be maintained as long as the resistance encoun tered by the plunger 2 .remainsthe same. valve Illa while preventing the-?ow of» fluid in the opposite direction.» Also branching on from the conduit 28 is a'concluit 32 leading‘to the con the ‘?ow of fluid therethrough fromith‘e'right If it should occur, that, for some;_reason, the 575 trol-cylinder 33. . The ‘control cylinder 33lha‘s'-re-' 2,14SQ85803 is c’iprocablyi mounted-i therein 3a‘ plunger? v‘.341 with tothati of Figures 1 and 2' so thatnofurther two" opposed . substantially -equal area 35- andL36. description thereof Iappears necessary; - The area ~35” is engagedgby- a spring- 20a =continu-. ously 'rurgingfthe ‘ plunger 34. 'leftwardly to thereby - tion. is by no. means limited to. the particular It will be.»understood.that..;the present ins/‘em cause the plunger 34 to. move the pump: Isa into 5 structureshown inthe drawing, but alsoembraces any. modi?cation falling within. the; scope of. the fulldelivery position; Theithrust of the spring 20a is adjustable a threaded extension mem Having thus fully described my invention, what ber 31 comprising a bore 38 for guidance of the appendedclaims. plunger 34. The bore 38 is connected through a conduit 39 with the tank [4a. The area 36 of 10 ' . . , .. I claim as new and desire to secure by Letters Patent, is: g 1. In a hydraulic system, the combination with a variable delivery source of pressure ?uid, of a conduit 40 with the conduit 28. ' a reversible ?uid motor having a pair of ports The control of the plunger 2a during its ad- I and operable in both directions by ?uid sup vancing movement fully corresponds to the con plied to said ports from said source, a ?rst ?ow 15 trol of the plunger 2 during the advancing move restricting means hydraulically connecting said the plunger 34 is hydraulically connected through ment thereof, and therefore the description of the advancing movement of the plunger 2a appears source with one of said ports, a second flow re stricting means connecting said source with the to be super?uous. However, as previously men other of said ports, conduit means adapted freely tioned, in the arrangement of Figure 2 also the 20 to exhaust either of said ports when the other is retraction stroke of the plunger 2a will be con being supplied with pressure ?uid from said trolled as to its speed. source, yielding means for continuously urging It may be assumed that the valve Ilia occupies said ?uid source toward maximum delivery posi the position in which the pressure line Ila is tion, a ?rst and a second double acting plunger in ?uid communication withthe conduit 28 while 25 each having two opposed and substantially equal simultaneously the conduitla communicates with areas thereon respectively connected with the inlet and the outlet of said ?rst and second ?ow the ‘conduit I3a. Pressure ?uid will then be de restricting means respectively, said plungers livered by the pump 19a through the choke 29 being connected to vary the delivery of said ?uid into the right hand portion of the cylinder la, thereby causing the 'plunger 2a to move leftward 30 source. 2. In a hydraulic system, in combination with ly. The ?uid expelled from the left hand por a variable delivery source of ?uid and a reversible tion of the cylinder larescapes through the check ?uid operable motor having a pair of ports and valve 9a, the conduit la and the conduit l3a operable in both directions by ?uid supplied to into the tank l4a. If now, for some reason, the resistance encountered by the plunger 2 dur 35 said ports by said source, a ?rst adjustable choke valve connecting said source with one of said ing its retraction stroke should change, the pres ports, a second adjustable choke valve connect sure drop across the choke 29 will also change ing said source with the other of said ports, con so that the pressure conditions in the control' duit means associated with said ports and adapted cylinder 33 will vary accordingly. As a result freely to exhaust one of said ports when the other thereof, the plunger 34 will be moved in a man ner similar to that described above in connec tion with the plunger I6, and will bring about a , corresponding change in the delivery of the pump l9a. Therefore, the initial ?ow of ?uid across the choke 29, and thereby also the original pres is being supplied with actuating fluid, yielding means continuously urging said source toward maximum delivery position, a ?rst and a second double acting plunger each having two substan tially equal opposed areas thereon, said ?rst and second plungers having their opposed areas re spectively connected with the inlet and the out the plunger 2 will be moved at substantially its _ let of said ?rst and second choke valves respec original speed. tively, said plungers being connected to vary the It will be obvious that by varying the setting 50 delivery of said ?uid source. of the chokes 6, 6a and 29 the desired speed of 3. In a hydraulic system, a reversible ?uid the plungers 2 and 2a may be varied. It will also operable motor having a pair of ports, a variable be clear that by setting the chokes 6a and 29 dif delivery source of pressure ?uid for selectively ferently the advancing speed and the retracting “ supplying actuating ?uid to said ports, means speed of the plunger 2 may be independently con 55 for connecting said source with one of said ports trolled. ' including a ?rst adjustable restriction, means " Third embodiment _ connecting said source with the other of said ports and including a second adjustable restric The system shown in Figure 3 makes use of tion, a ?rst and a second check valve bypassing the same principle illustrated in Figures 1 and 2 and similar parts are designated by the same said ?rst and second restriction respectively, each of said check valves being adapted to conduct numerals as in Figure 1, but with the additional character 0. However, in Figure 3 the plunger ?uid away from said motor but not vice-versa, adjustable yielding means for continuously urg 40 to be controlled has a piston portion 4| with ing said ?uid source toward maximum delivery substantially equal areas 42 and 43. Further more, the position of the four-way valve I00 and 65 position, a ?rst and a second double acting plunger having two- substantially equal opposed the choke 60 has been reversed with regard to areas thereon associated with said source and the pump 190. In other words, the delivery of connected to vary the delivery thereof, said ?rst the pump [9a to either the area 42 or the area and said second plungers each having the opposed 43 must always pass through the choke 6a so that the advancing as well as the retraction stroke of 70 areas thereof respectively connected with the inlet and the outlet of said ?rst and second ?ow the plunger 40 is controlled. However, the set? restrictions respectively. ting of the choke Ba will equally affect the con 4. In a hydraulic system, in combination with trol of the plunger 40 in its advancing and re ae?uid source of variable delivery, a reversible tracting directions. Otherwise, the operation of sure drop across this choke will be restored and the system shown in Figure 3 fully corresponds 75 ?uid motor having a ?rst and a second port, ?rst 2,408,808 and second ?ow restricting means connecting said source toward maximum ‘delivery position, said source with said ?rst and second ports re spectively and each operable to establish‘ a pre and ?rst and second ?ow controlling means con nected to vary the delivery of said source and each comprising oppositely e?ective fluid‘ operable means connected respectively with the inlet and determined pressure di?erence between its inlet and outlet in response to ?uid ?ow toward the associated port but to permit free ?ow from the said port, yielding means continuously urging the outlet of one of said ?ow restricting means. i ' WALTER ERNST.