US1885077A - System of control - Google Patents

Description

Oct. 25, E CANNON 1,885,077

SYSTEM op CONTROL Filed oct. 15, 19'24- to provide a Patented Oct. 25, 1932 .UNITED STATES PATENT oFElcE EARL CANNON, 0F PHILADELPHIA,

IENNS'YLVANIA, ASSIGNOR TO AMERICAN :FLUID `IIOTORS COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION 0F PENN- SYLVANIA l n l SYSTEM OF CONTROL Application metiy october 15, 1924. serial No. 743,696.

My invention relates to power apparatus,

and it has particular relation to apparatus of the hydraulic type. v n

One object of my invention is to provlde a fluid motor and means whereby the direction of operation and the rate of movement of the motor may be controlled.

Another object of my invention is to augment the variable speed feature of a reversiy ble, variable-stroke pump by differentially associating therewith apparatus havmg a fixed speed ratio.

A further object of my invention iste pro-v vide a novel power Vsystem which includes a hydraulic motor having equal piston speeds in opposite directions,-such desired result being obtained without the use of a double acting ram and tivo single acting cylinders or by anauxiliary cylinder with a displacement equal to the volume of the piston' rod. y

A still further object of my invention is valve and pump arrangement in v connection with a hydraulicmotor which permits equal pressures per square inch on opposite sides ofthe piston during the operation of said motor in at least one direction.

A still further object omy invention is to provide a hydraulic motor having a differential, quick-return stroke adapted to actuate a machine tool, say, for instance, a broaching tool,ytogetlier wi -hi a reversi-ble variable- Y position; and

stroke pump for operating said motor.

- With these and other objects and applica- I Ations inmind, my

invention, further consists in the details. of construction and operation, hereinafter described and claimed and illustrated in the accompanying drawing, wherein l Y y' Figi is a view partially diagrammatic and partially structural of one form of embodiment-of my invention;

Fig. 2 is a view similar to Fig. 1, but showing the apparatus in the reverse operating Fig. 3 is a, detail sectional view of the device connecting the operating lever and the stroke-controlling element of the pump.

In the illustrated form of embodiment of my invention shown in the drawing, a hydraulc motor l comprises `an elongated cylinder 2 having a piston 3 mounted therein, the latter being provided with a piston-rod 4 which extends through a stuing box 5 at one end 6 of 'the cylinder 2. In one application of my lnvention, the piston-rod 4 is connected .to the tool of a broaching machine (not shown) though of course my'invention is not specifically limited to such use.

' The connection of the piston-rod 4 to the broaching machine may be such that the working stroke occurs as the piston-rod 4 moves either into or out of the cylinder 2,

For purposes of illustration, thefo'rmer hasl with a reversing, Vstroke-controlling element 15 of usual form and it has end portions 16 and 17 extending from opposite sides of the pump 7. The end portion 16 of the reversing element 15 is operatively associated through a lost-motion connection 18 (F ig. 3) with a main control lever 19 having a pivotal mounting at 21 on a supporting member 22.

The spring 'telescoping connection 18, which is designed vto `permit a continued movement the limit of the movement of the reversing element 15 may comprise a tubular member 23 having the ends thereof closed by abutments-24 and 25 which are movable inwardly against the Jforce of a coil spring 26 extending therebetween. The abutments 24 and 25 are provided with axially aligned perforations 27 and 28 adapted to receive-the ends of a rod 29. One end of the rod 29 extends beyond the adjacent abutment 25 and is provided -with locking nuts 31. A head 32 serves to connect the end of the rod 29 adj acent to the abutment 24 to the main operating lever 19, while a tubular'extension 33 connects the tubular supporting member 23 of the operating lever 19. beyond t The variable capacity pump 7 is providedl l.

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with the end portion 16 of the reversing elei ment 15.

When a force is applied to the operating lever 19, a corresponding. force isimparted to the reversing, stroke-controlling element 15 through lthe telescoping connection 18. When the element 15 has moved a desired amount, it engages one of a pair of abutments 34 and 35 to be described more fully hereinafter, thereby interrupting the further movement of the reversin element 15.

19, which may be necessary for reasons to he set forth hereinafter, causes an inward movement of one of the abutments 24,-25 against the force of the spring 26, all as will be understood by those skilled in the art. The stroke of the operating lever 19 may thus be made equal to or greater than the desired stroke of the reversing element 15.

The extent of movement of the reversing element 15 and hence the stroke of the pump 7 may .be varied in either direction by the adjustable abutments or stop wedges 34, 35 disposed on opposite sides of a block 36 carried onthe end 17 of the reversing element 15. The stop wedges 34, 35 maybe adjustably mounted on rods 37 having a threaded connection witha supporting frame'38 extending from the frame of the pump 7. The stroke of the pump 7 on either side of the neutral position may thus be varied from zeroV to the maximum of the pumpby vertically adjusting the stop Wedges 34, 35.

The piping 11, which is operatively associated with the pump 7, the hydraulic motor 1 and a storage or so-called compensation chamber 39, comprises a pair of pipes 41 and 42 which extend respectively from the ports 8 and 9 to a four-way reversing valve 43, the pipe 41 being also connected by means of a branch pipe 44 to the port 13 in the end 14 of the cylinder 2. The other end 6 of the cylinder 2 as well as the storage chamber 39 are connected respectively by pipes 45 and 46 to the four-way control valve 43,-the disposition of the several pipes at said valve being such that when the parts are in the position shown in Fig. 1, the port 9 of the pump 7 is connected through pipes 42 and 45 to the; end 6 of the cylinder 2. At the same time, the port 8 of the pump 7 is connectedl to the storage chamber 39 through the pipes 41 and 46 and to the end 14 of the cylinder2 through the pipes 41 and 44.

When the connecting valve 43, however, is moved into the position shown in Fig. 2, the port 9 of the pump 7 is 'connected to the storage chamber 39 through the pipes 42 and 46 and the port 8 of said pump is simultaneously connected to both ends of the cylinder 1 y through the pipes 41, 44 and 45., The tourv- The continued movement of t ev operating lever.

usedom* in Fig. 1 to that shown in Fig. 2 through an interconnecting link 47 and arm 48.

Assuming the reversing stroke-controlling element 1 5 to be so disposed that with the connection-reversing valve 43- in the posi- 70 cross sectional area. between the piston rod 4 75 and the piston 3, causes said piston 3 to move toward the end 114 of the cylinder 2. As

vhereinbeiore noted, this movement of thev piston 3 may be termed the working stroke.

The movement of the piston 3 causes the 80 fluid contained in the end 14 of the cylinder 2 to be ,discharged therefrom through the pipe 44 into the pipes 41 and 46, the pump 7 drawing in a certain quantity of the 'luid and the storage chamber 39 receiving the 85 excess. The rate of movement of the piston 3 on the present stroke may be controlled by verticallyadjusting the stop wedge 34 inasmuch-as the latter determines the quantity of liquid propelled per revolution from the pump' 7 through thepipe 42.

When the operating lever 19 is ymoved to the left, the control valve 43 and the reversing element, 15"are corerspondingly moved from the positions shown in Fig. 1 to those shown 95 inFig.l 2. The movement of the element 15 into its reversing position therefore causes the pump 7 to discharge Huid through the pipe 41 rather than the pipe 42 as in the preceding position. Since the pipe 41 is now l10? connected by pipes 44 and 45 to the opposite ends 14 and 6 of the cylinder 2, a force is exerted on the piston 3 which is proportional to the cross sectional area of the piston rod 4.

As a result, the piston 3 moves to the left and 105 traverses'what` has been termed for purposes of illustration the return stroke. With the pump 7 discharging into the pipe 41, iuid is drawn into vport 9 from the storage chamber 39 through the pipes. 42 and 46. The rate of 110 movement of the piston 3 during the present return stroke may be controlled by the stop wedge 35 independently of the stop wedge 34.

Inasmuch as the extent of movement of the four-way valve 43 may be materially greater 115 than that of the reversing element 15, it is seen that the telescoping connection 18 between said reversing eleinent 15 and the main operating "lever 19 permits the continued movement of the latter after the end member 12o 36 of the reversin element.15 has engaged one of the stop we ges 34-35. y

, ln View of the foregoing; it may readily be seen that the rate f operation of the piston 3 in either 'direction can be directly controlled 125 by the stop wedges 34 and 35 so that various speed combinations can be obtained. For example, ifthe stop wedges 34 and 35 are adjusted to cause the pump 7 to have a short wor-g stroke and a long return stroke, then 13e the working speed oi tlfe motor 1 is exceedingly slow compared with the return speed.

'the use of the usuall double-acting ram and two single-acting cylinders. In order to efby' the diii'erence between 6-of the cylinder 2, ure, the propelling :Eect such desired result, the area represented the cross sectional area of the piston 3 and the piston-rod 4, must be equal to the cross sectional area of the piston-rod 4. The reason for this is apv arent in view of Fi s. 1 and 2, since in the ormer 'a propelling uid is admitted/only to tbe end whereas in the other ig- Huid is `admitted to lboth ends of the cylinderA 2. If the area of the piston-rod 4 is still further increased, the net effective area on the working stroke becomes less than that on the return stroke so that the ratio of the piston speeds on said strokes for constant pump discharge is reversed, causing thewgreater speed on the working stroke. 1

Another desirable result characteristic of A my apparatus is the absence of leakagebr slip past the piston 3 at least during one of itsy strokes, inasmuch as the insertionuof a propelling iui intoboth ends of the cylinder 2 results in e ual` pressures per square inch be-1 ing exerted on the opposite piston faces. This is of greater advantage when the piston-rod 4 is large relative to the cylinder 2, as then higher pressures may bel usedv during the differential stroke. 5"

While I have shown only one form of embodiment of my invention, for the purposefof describing the same and illustrating its principles of construction and operation, it is ap-I oparent' that various changes and 'modifica-H tions may be made therein without de arting sidesl of vstia piston andV subsequently the other of said p1 s tol the havin the sma er pressure area, inclu ing a control valve, and common means for actuating the latter and said element, ,said last-mentioned means includin a lostmotion device permitting a di erential side of said piston said means y operation of said means in actuation of the control valve and said element.

2. Hvttraulic apparatus comprising a pump ving a stroke-controlling element,

adjustable means for varying the' movement of the stroke controlling element, a fluid motor, means including a control valve for operatively associating said pump and said motor, and means for actuating said valve and said element.

3. Apparatus of the class Adescribed in- -cluding a puinp having a'variabl movable flow-controlling element, means or adjust- ,ingthe extent of movement' of said element, a Huid motorfa connectingvalve operatively associated with said pump and said motor, and meansfor' actuating said valve and said element, said means having a lost-motion connection with said element whereby to permit variations of the movement thereof while maintaining a uniform movement of the valve.

4. A pump stroke controlling'element, -means for adjustling the extent of movement of said element, a iuid motor, a four-way valve operatively associated' with said pump and said fluid motor, and a common operating lever Yfor said valve and said element, said lever having having a vai-ably movable a/ lost-motion 'connection to said element whereby to permit a uniform movement of said valve accompanied by variable movements of the element. A

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. from the spirit of my invention, and desire,

therefore, that only such limitations shall-be imposed vthereon as are indicated in the a pended claims prior art.

or `as are demanded by the Iclaim: I I I l ,1. In a hydraulic power system, the combi.- i nation'with a iuid motor provided with `a piston having different effective lareas 'on'the opposite s1desthe`reof,-o f a reversible, varia'- ble-str ke positlve i elementfor reversing saidpump and for controllin extending from said pump,

l l'b'tivelyeonnecting one of said'pipes teboth the stroke thereo apair of pipes means for operadisplacement pump, an?

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