US1418953A - Controlling apparatus for piston pumps - Google Patents

Description

F. MARTIN. CONTROLLING A ARATus FOR PISTON PUMPS. APPLICATION FILED 061123, 1920.

2 SHEETS-SHEET I.

S P M U P N 0 CONTROLLING APPARATUS 2- APPLICATI ON FILED 23, 1920.

Rammed J1me 1922;

-2 SHEETSSHEET 2.

use are FRIEDRICH MARTIN, OF ESSEN GERMAN Y, ASSIGNORLTO FRIED. KRUP]? FATNT] F-FHQL- AKTIE GEsEL mSonAFT, or nss u on-rns-enne, GERMANY,

v miss-a.

CONTROLLING APPARATUS FOR PISTON PUMPS.

Specification of Letters Patent. Patented June 6, 1922.

.e nca'uoninea October as, 1920. Serial No. 419,043.

To all whom'it may concern Be it known that I, F RIEDRIoH MAR'r iv, residing at Essen, Germany, a citizen of the German Republic, have invented a certain new and useful Improvement in Controlling Apparatus for Piston 'Pumps, of which the followingis a specification. The presentinvention relates to controlling apparatus for pistonpumps driven by a shaft and having variable stroke-length, in

which a controlling piston, intendedto alter.

the stroke-length of the working'piston during the operation of the pump, is under the influence of the fluid pressuregenerated by the pump as Well as of that of a power source acting in opposition to said pressure, so that the fluid pressure tends to displace the controlling piston in the direction of diminishing the stroke-length of the working piston. If

with a pump of this kind the pressure conduit is shut off during operation, an increase of pressure will occur-in the pump, which causesashortening of the stroke-length of the piston. If the chamber containing the shut off pressure fluid were completely tight,

then the stroke-length of the Working piston would bediminished to the value of zero,

and a condition of inertia would occur, in which the pump would have no pressure,

evenby continued rotation of the driving shaft. Really, such a condition can never be attained with the known pumps. On the contrary, as the stroke-length of the working piston, on account of the. unavoidable leakage, can only be diminished onto an.

amount with which the pump delivers just i so much fluid as corresponds to the losses by leakage, then a condition of inertia will occur with the saiddiminished stroke-length,

wherein the pump continues to work under high pressure without producing useful work. In this resides a considerable disad vantage, as the pump is stressed and worn outunnecessarily.

The present invention has for its object to overcome this disadvantage.

. The invention is illustrated on the accom-- panying drawing as applied to a m'ultiplecylinder piston pump of a hydraulic power plant,-the axes of the pump cylinders being arranged on a cylindrical surface around-adriving shaft common for all the pump cylinders.

-Fig. 1 shows aside elevation, partly in section,of one embodiment of the invention,

ing' plant,

0 mounted on the valvebox C.

together with the adjacent parts of the pump- Fig. 2 a section, in l rger scale, ofa modified detail of the subi ect matter of the invention, and Fig. 3 is a view on a larger scale showing the means for varying the stroke-length of the pump.

A is the housing of the pump, to which are connected the suctionspipe-a and a pipe a ofthe pressure system. The pump comprises, as usual, aplur-ality of stationary cylinders A", arranged parallel to their driving shaft B, Fig. 3. In each cylinder is a piston L, connected by a rod U with a cam disc V, whichis in turnconnected with the housing A by a joint comprising two pairsofpins o and S, at right angles to each other. The axes of said 'pins intersect in a point 0, forming the center-of said joint and lyingin the axis of the shaft B. The cam disc V is mounted, through a ball bearing W, on a support B, which is ad justably mounted on a disc B rigidly connected with the shaft so that it can turn, relatively to the latter, about an axis'which lies at right angles to the axis of shaft B,

at the point 0, To adjust the support B, a

sleeve D is provided, which can slide but not turn upon shaft B, which is driven. at a constant speed, as by an, electric motor. Sleeve D is provided, on each side 'of shaft B, with a rack d meshing with a gear sector Z. Each of .these sectors is rotatably mounted on a bridge 6 rigid with the disc B and meshes with a gear segment Z2 on the support B, so that the latter can be turned about its axis, passing through center 0,'by a displacement of sleeve -D, which, accordingly varies the stroke of the piston'L, it being shortened when said sleeve is moved in the direction of arrow Into the pressure conduit there is inserted between-the pipe. of and-a pipe of connected thereto, return valve a the valve bodya of which, acted upon by a springe tends to shut off the pipe a from the pipe (11?, which leads directly to the pump housing- A. The pipe (1 opens into a central port 0 of a slide 'valve box C, within which a slide valve C may be displaced b'ya hand lever Two ports 0 and c are provided in the valve box C,

one on each side of the :central port 0 and adapted to be closed simultaneously by the slide valve C From the port 0 a pressure the mutt D. The other arm of the bell crank lever it has hinged connection, through a link with a single-arm lever F, also rotatablymounteil on the pump housing A. By means oi a rod the lever F is also in ninged connection with the rod (3: ot a small piston rlisplaceable within a cylin der ii said piston rod il having stopcollars g and g As it will be seen from the above given description the piston rod G is in constant positive connection with the muff D, in such a manner that a displacement of this piston rod in the direction of the arrow ;1 causes a displacement of the mutt D in the direction of the arrow a2, and, as a consequence, a shortening of the stroke-length of the working piston The collar g is now so arranged that it limits the displaccmentot the piston rod in the direction of the arrowg/ when the mutt D has arrived in the position that corresponds to thezero length of the stroke of the working piston. On the other hand, the collar 91* limits the displacemcnt'ot the piston rod. G in the direction opposite to the arrow 3/ when the Inuit D has reached the position corresponding to the maximum strokcdength of the working piston. The

piston rod G has different diameters on.

both sides of the piston Gr, so that the piston G acts as a differential piston, its annular area to the right on the drawingbeing the greater. The free end of the lever. F carries a rollerj and pro ects into a slot 7L2 running in axial direction, of a piston rod HP provided with a stop collar h and carrying a piston H Operating in a cylindenA At its end remote from the piston H, the slot k terminates with an abutment h co-operating with the free end of the lever F which carries the roller 7'. The righthandend of the cylinder A is, by means of a passage a, permanently connected with the left-hand end of the cylinder A The right-hand end of the cylinder A is, moreover, connected with the pipe a through a pipe a The lefthand end of the cylinder A is connected, by means of a pipe 2' with a bottle J, which contains compressed air, the pressure of which is approximately equal to the mean operating pressure of the pump. The right-hand end of the cylinder HQ, and, as a consequence, also the left-hand end of the cylinder A, are therefore constantly under pressure.

ln hearings on the cylinder it is carried bell crank lever hi hi}, the one arm, hi, of which extends into the path of the collar 71, ct the piston rodlll The other arm, it, of the bell crank lever is connected by means oi a link Ill. with a d'oublcnrmcil lever l mounted on the valve casing N. The link iii extends beyond the lever i and passes through an eyelet 11, on the valve casing it, with suilicient play, so that the bell crank lever iii K and the lever P may rock on restricted within certain limits.

A rod 2 slidable in the valve casing N, engages one of the arms of the lever P, and another rod p also slidable in the valve casing N, engages the other arm of this lever. In the valve casing N are provided two double chambers, which each consist of two communicating chambers .21 n and a n. The chamber or? may be shut off from the chamber a, into which the rod 11 extends, by means of a valve Q, actuated by a spring while the chamber 71* may be shut off from the chamber n, into which the rod 20 extends, by .means of a valve R, actuated by a spring 7. The described parts are so arranged that the two rods 19 and intended for opening these valves, simultaneously abut against the valves Q and B, when the two latter are in their closing position. As long as the arm K of the .bell crank lever K K is out of touch with the collar 703 of the piston rod H the lever P, through the in connected with the right-hand end of the.

cylinder A through a pipe n The chamber a is connected with the suction chamber of the. pump through a pipe a and the chamber 1r with the righthand end of the cylin dcr .A through a pipe n collar k is out of touch with thc arm K of the bell crank lever K K and the valve Q, as a consequence, is kept in its opening position by the spring m as shown in the drawing, the right-hand room ofthc cylinder A will consequently communicate with the suction chamber of the pump through the path a n a a n There is consequently no pres sure in this room of the cylinder A As the left-hand room of the cylinder AJ, as stated hercabove, is constantly under pressure, the piston rod G tends, therefore, to move in the opposite direction to the arrow and keeps, consequently, the roller 7 of the lever F in contact with the abutment surface it? of the slot h? of the piston rod As long as the -H both when it is at rest and during a displacement in anydirection. As lon 'as position the stroke-length of the piston of the pump is depending. The position of the collar k is now selected in suchwise, that than thatstroke-length with when'the piston H moves in the direction ,of the arrow y, the collar comes 1n contact with the arm K of the bell crank lever K K only when the piston H has attained a position to which corresponds a comparatively short stroke-length of the working piston., This stroke-length of the working piston must, however, be sufliciently greater than the stroke-length by aid of which the pump would deliver only a quantity of fluid which corresponds to the losses by leakage which latter may be ascertained by experience. On-

the further displacement of the piston H in the direction of the arrowy, a force-closing positive connection will therefore exist between the piston H and the valve Q (by intermediary of the collar it the bell crank lever K K the rod M, the lever P, and the rod 2 which connection results in that the valve Q, approaches to its seat. The positive connection, which existed before the collar it comes to'make contact with the lever arm K, between the piston Hand the vmufl" D, will then remain unchanged, so

that no further shortening of the strokelength of the working piston .will occur.-

The conditions are now so" chosen. that the length of the piston stroke present. at the moment when the valve Q reaches its seat, is still'greater, for a small convenient amount, Which the pump would deliver so much fluid only as is lost by leakage.

For the normal operation of the pump, the parts of the described apparatus are in the position representedin the drawing. The. piston valve C is then adjusted in such a manner that th-e pressure pipe 0 leading to the workingmachine is inconnection with the pipes a and a leading from the pump, and the pipe ,0 serving to lead off the waste f water from the working machine, is connected with the drain pipe 0. Further, the collar h of the piston rod H is out of contactwith the arm K of the bell crank -lever K K so that the valve Q is held in its open position by the spring m and consequently the controlling'piston H is in force-Closing positive connection with the muff D, on the position of which latterthe stroke-length of the working piston depends.

The puinp then operates just as pumps of known art referred to in the preamble, as the controlling piston H, on whose position the stroke-length of the working piston depends, is subjected to the fluid pressure, in

' the roller 7 of the lever F such-a manner that. the fluid pressure tends to displace the controlling piston in the direction of shortening the stroke-length of the working piston, that is, in the direction of the arrow 3 If, now,'the consumption of pressure fluid is slight, then the piston H adjusts the pump automatically to a correspondingly short stroke-length of the working piston ;.and inversely, for a greater consumption of pressure fluid, to a correspondingly greater stroke-length.

The individual advantage of the subject matter of'the present invention will fully appear if the delivering action of the pump is broken off, by adjusting, the piston valve C so that the-ports 0* andc are closed. An inished and the rod p will belowered and the rod 0? raised through the intermediary of the bell crank lever K K the rod M and the double-armed lever P. a

As a consequence, the valve Q, under the action of the-spring. g comes to shut off to take its seat, the valve R is lifted by therod p against the action of the spring ,1, so that pressure fluid on the right-hand side of the piston G enters into the cylinder A from the cylinder A through the pipe 71 the chambers n and n passage a and pipe 127. Now the piston G comes to act as an independent auxiliary motor. The pressure fluid namely acts n'owon both sides of the piston G after'the' valve R has been lifted.

As, however, the right-hand annular area of the pistonG is the greater one, the latter. will of the arro'w-y,.

be displaced in the direction disengaging the abutment surface h of the slot 78. On this displacement of the piston G, the mufi' D is still further displaced .in the direction of the arrow 01:, and the 'stroke-length of the working until it finally becomes zero, when the collar 9 has co ne to strike against the front face ofthe cylinder A.

As no more fluid circulation can take piston consequently diminishedstroke-length of the pump is further dlminlltl rec

A F again comes in contact with the abutmenthas been at y ment ot-the p arrow 1 1S upossible.

contrary, now moves gradually towards the right under e action of the air pressure existing on it lett-hand side and in consequence of the lealrage existing in the cylinder the pipes a and a, and at the piston valve C 911 thisnlovement towards the right the piston H does not act upon the lever l as the sloth is long enough to prevent such action. The piston G remains consequently in its extreme position, which corresponds to the zero length of the piston stroke. The arm K of the bell crank lever K which abuts against the collar h oi the piston rod H follows the movement of the piston l'l so that the valve R is' gradually lowered and the rod p again approaches the valve Q. At that moment, when the valve B has reached its closing po sition, the rod p comes in contact with the valve Q3. On the further travel of the piston H, the valve Q will beraised, so that the right-hand side ot the cylinder A comes again in communication with the suction chamber of the pump through the path a n n a a its a consequence, the fluid pressure on the leztthand side of the cylinder A preponderates and the piston G then travels to the right until the roller f of the lever surface 71, 01 the piston rod H As the pump 1s now again adjusted to a-strokelength which delivers a fluid quantity that is considerably greater than the losses from leakage, then the piston H again travels to the left and the above-described cycle of actions is repeated. The piston G namely returns to its extreme position corresponding to the zero length ofthe piston stroke and remains again for a longer time in thisposition whereupon it again temporarily moves to the right and immediately thereupon returns to its extreme position. *Therefore the pump with exception of short interruptions, remains without pressure. lVith the present invention the disadvantages presentin pumps of known art as above described, are, therefore avoided, which consist in that the pump, even when it does-not produce any useful work, continues to operate-with only a certain dead stroke-length corresponding to the losses by leakage, under higher stress and corresponding wear.

' If the working machine is to-be restarted, the ports 0 and 0 have to be opened through the displacement of the piston valve 0*. As

a consequence, the pressure diminishes in the pipes at and a, as well as on the right hand side of pi 11 ll. which latter. actuated by the air presurc on its left-hand side, now travels quickly to the right. This movement of the piston l car -es the piston to travel to the right, m l the roller of the lever l again comes into contact with the abutn'icnt sur'thrce l1, oi the piston rod l l There now again exists a positive torceclosing connection between the controlling piston H and the mull l), upon the position of which latter the stroke-length ot' the pump depends, soon as the piston it has traveled so far that, the resulting strokelength corresponds to the iluidconsumption of the working machine, the condition o'l inertia again sets in from which the description of the operation started.

lit the piston valve C remains a longer time in the closing position, the piston G, as related above, can travel temporarily so 'lar to the right that the roller f of the lever F again comes into contact with the abut-' mentsuorlaceh ot the piston rod H During this movement of the piston G there will occur an intermediary position to which corresponds a stroke-length with which the pump just would cover the lossesby leakage. It now the displacement of the piston G should take place very slowly, it would occur that the pistons G and H, after several movements back and forth, would at last adjust themselves, so, that the piston G, on the one hand, will assume the intermediary position above mentioned, and the pump, therefore, only delivers so much fluid as the losses by leakage amounts to; and that, on the other hand, the valves Q and R, whose position is controlled by the piston H, simultaneously assume their closing position. The pump would then continuously work with the stroke-length corresponding to the position of the piston Gr under high stress and corresponding great wear. In order to avoid this disadvantage, which has to be prevented just by thisin'vention, care must be taken that the piston G is quickly moved .so far out oft-his extreme position, which corresponds to the zero stroke-length, that the; roller f ,comesinto contact with the abutmentsurface h of the piston rod H For this purpose, with the embodiment represented in Fig. 1, the outer diameter ofthe valve Q must be large enough so that the passage area permits a quick flow of the fluid present on the right-hand side of the piston G in the cylinder A even with very small stroke-length of the valve Q. In Fig. 2 is shown an embodiment which insures an absolute safe manner of operation, even with comparatively small diameter of the valve Q.

In this second embodiment, a two-part muff T is inserted between the rod 37 and I the valve Q, which mufi is slidable upon the rod 79 and bolt g having a head and secured to the valve Q. The muff T. has,

on the one hand, an abutment surface 23 with which it is able to make contact with the head of-the bolt g when it' approaches the valve Q, and on the other hand,--an abut- I ,ment surface 6 for the rod 2 These parts 25 Will first be' compressed by the rod p areso arranged that, on the one hand, the rod p 'is in contact with the abutment surface t and, on the other hand, the abutment- Sui-facet is in contact with the heady; of the bolt 9", when the valve Q assumes its closing position and when the lever P is. in that angular position in which in the embodiment of Fig. 1 the rod 12 comes to touch the valve Q. Between the muff T and the valve Q there is inserted a spring 7 t the strength of which is such that-when simultaneously the abutment surface t is in contact with the head 9 of the bolt 9 and the rod 79 with the abutment surface 25 this spring exerts a force against the-valve Q that is nearly the same as the resistance with which the valve Q actsagainst displacement from: its closing to its opening position under the action of the fluid pres sureacting upon it and of the pressure of. the spring 9 If now, with the last described apparatus, a slow displacement of thepiston to the right takes place after the Zero strokelengthhas been adjusted, then the spring after it has come to touch the abutment surface of the muff T, the valve Q, which is under the influence of the spring 9 and the. fluidpressure, remaining inzits closing position. As soon as, however, on the further movement of the rod 79?, wherein the muff T now partakes, the abutment surface t has come into {contact with the head 9 of the bolt Q2, then'the valve Q is lifted on the further displacement of the piston 'H,

- 25 over the pressure from the spring 9 and.

the pressure fluid. The valve Q then immediately moves so far in the opening direction, independent of the rod 39 that even with a comparatively small diameter of the valve Q, a passage of suflicient area'is produced. The pressure fluid can now flow out quickly from the cylinder A, and the Y piston G, as soon as it has started, travels therefore immediately and without fail so far to the right, that the roller f of the lever Flcomes incontact with the abutment surface h of the piston rod H a As the pump from now on is adjusted to a stroke-length by which the delivered fluid.

quantity is considerably greater than the losses by leakage, the controlling piston H again travels to the left, so that the rod p larger area of the differential piston G, so

that this latter travels to the left and adjusts the pump'again to the zero stroke-length.

A similar device as is providedto obtain a quick opening movement for the valve Q, as illustrated in Fig. 2, may naturally also be applied to obtain a merit for the valve R.

I claim? quick opening move- 1. A controlling apparatus for piston pumpsv with shaft drive and a variable stroke-length comprising an adjusting mem- -'ber for varying the stroke-length of the pump, a controlling'piston, means connecting said controllingpiston to said adjusting member, means enabling said controlling piston to be actuated by the fluid pressure generatedby the pump in the senseof shortening the stroke-length of the pump, a source v oflp'ow'efr acting on the controlling piston in opposition to thefluidpressure of the pump, means for ad usting the pumpso that it will be without pressure, an auxiliary motor for actuating said-adjusting means, and means operable by the controlling piston when having reached a position corresponding to a pump in the sense of shortening the strokeated by the fluid pressure generated by the length of the pump, a source of power acting on the controlling piston 1n op osition to the fluid pressure of the pump, an means operable by the controlling piston when havmg reached a position corresponding to a' comparatively "small stroke-length for causing said auxiliary motor-to function wherediminished to the value-of zero.

by the stroke-length of the pump may be 3.!& controlling apparatus for piston pumps with shaft drive and a variable stroke-length comprising an adjusting member for varying the stroke-length, a controlling piston and an auxiliary motor, means connecting said controlling piston and auxiliary motor to said adjusting member and allowing the adjusting mem/ber to .be' displaced by said auxiliary motor independently 'of lac 100 comparatively small stroke-length forcaussaid controlling piston in the sense of shortening the stroke-length of the pump. means enabling said controlling piston to be actuatedby the fluid pressure generated by the pump in the sense of shortening the stroke length of the pump, a source of power acting on the controlling piston in oppositionto the fluid pressureof thepump, and means operable by the controlling piston when having reached a position corresponding to a comparatively small stroke-length for causing said auxiliary motor to function whereby the stroke-length of the pump may be di-. minished to' the value of zero.

4. A controlling apparatus for piston pumps with shaft drive and a var1able stroke-length comprising an adjusting memher for varyingthe stroke-length of the pump, a controlling piston, means connecting said controlling piston to said ad ust1ng member, means enabling said controlling piston to be actuated by the fluid pressure generated by the pump in the sense of shortening the stroke-length of the pump, a source of power actin on the controlling piston 1n opposition to t e fluid pressure of the pump, means for adjusting the pump so that it Wlll be without pressure,an auxiliary motor for actuating said adjusting means, said auxiliary motor having a cylinder, a'piston work ing therein under the action of the flu1d pressure generated by the pump and a starting gear operable by the controlling piston when having reached a position corresponding to a comparatively small-stroke-length for causing said auxiliary motor to function. I

5. A controlling apparatus for plston pumps with vshaft drive and a variable stroke-length comprising an adjustlng member for varying-the stroke-length of the pump, an auxiliary motor having a cylinder permanently communlcating on-its one side ing gear for controlling said other side of:

the cylinder to communicate either with the pressure chamberof the pump, or with said discharge conduit, a controlling piston, means connecting said controlling piston and said differential piston to said adjusting member and allowing the adjusting member to be displaced by said differential piston when drivenby the fluid pressurev acting on its larger area independently of said controlling plston in the sense of shortening the stroke length of the pump, means en'- abling said controlling piston to be dis- ;placed by the fluid pressure ofthe. pump also in the sense of shortening the strokelength of the pump, and a source of power acting on the controlling piston in oppositionto the fluid pressure of the pump, said starting gear of the auxiliary motor being operable by the controlling piston when having reached a position corresponding to a comparatively small stroke length for causing said auxiliary motor to function in the sense of shortening the stroke-length of the pump whereby the stroke-length of the pump may be diminished to the value of zero. a r

6. A controlling apparatus for piston pumps with shaft drive and a variable stroke-length comprising an adjusting member for varying the stroke-length ofthe pump, a controlling piston, means connecting said controlling piston to'said adjusting member, means enabling said controlling -piston to be actuated ,by the fluid pressure generated by. thepump in the sense of shortening. the stroke-length of the pump, a source of power acting on the controlling piston in opposition to 'thefluid pressure'of the pump, means for adjusting the pump so that it will be without pressure, an auxiliary motor for actuating said adjusting means, said auxiliary motor comprising a cylinder, a piston working therein, means connecting said cylinder on the working side of said piston to the pressure chamber of the pump, a discharge conduit communicating with said cylinder on the working side of the piston'also, a starting valve for controlling the communication between said cylinder and the pressure chamber of' the pump, a

push rod for opening said starting valve operable by the controlling piston when'having reached a position corresponding to a comparatively smallstroke-length, an outlet valve for controlling the communication between said cyllnder and the discharge coii duit, a second push rod positively connected to said first-named one for opening said outlet valve when said starting valve is closed,

an abutment piece interposed between said second push rod and said outlet "alve, and a spring interposed between said outlet valve and said abutment piece whereby during the opemng of vsaid valve said spring will first be compressed. t

7. 'A' controlling apparatus for piston pumps with shaft drive anda variable stroke-length comprising an adjusting member forvarying the strokedength of the pump a controlling piston, means connectmg said controlling piston to said adjusting member, means enabling said controlling shortening the stroke-length of the pump, a source of power acting on the controlling piston in oppdsition to the fluid pressure of the pump, means for adjusting the pump so that it will be without pressure, an auxpiston to be actuated by the fluid pressure generated by the pump in the sense of iliary motor for actuating said adjusting means, said auxiliary motor comprising a cylinder, a piston working therein, means connecting said cylinder on the working side of said piston to the pressure chamber of the pump, a discharge conduit communicating with said cylinder on the working side of the piston also, a starting valve for controlling the conimunication between said cylinder and the pressure chamber of the pump, a push rod for opening said starting valve operable by the controlling piston when having reached a position corresponding to a comparatively small stroke-length,

-an outlet valve for controlling the communication between said cylinder and the discharge conduit, a second push rod positively connected to said first-named one for opening said outlet valve when said starting valve is closed, an abutment piece interposed between said secondpush rod and said outlet valve and having sliding movement relatively to said push rod, and a spring interposed between said outlet valve and said abutment piece whereby during the opening of said valve said spring will first be compressed.

The foregoing spec'ification signed at Essen, Germany, this 17th day of June, 1920.

FRIEDRICH MARTIN.

In presence of-' HANS Go'rTsMANN, JOHANN DEGKERS.

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