US2490823A - Hydraulic-pneumatic system - Google Patents

Description

HYDRAULIC- PNEUMATIC SYSTEM Filed OOb. 14. 1946 INVEN TOR. Hou/ARD HMAA/N//vq Patented Dec. 13, 1949 UNITED STATES l PATENT OFFICE I e 2,490,823 I HYDRAULIC-PNEUMATIC s YsTEM 'Howard Manning, Meadville, Pa. Application october 14, 1946, serial No. 703,227

This invention relates to systems embodying fluid motors of the expansible chamber type and controlling means for causing the motors to perform useful work. The word iluid is intended to include both gases and liquids.

More particularly, the present invention is concerned with a system embodying a servo-motor that is under selective manual control and sufliciently hydraulic in character to permit the working or moving element of the motor to be stopped and held accurately in any desired position.

Hydraulic apparatus has greater versatility than a similar apparatus operated by compressible uids, but it is more costly, especially in the pump and in .the various parts designed to seall a purely pneumatic system, although more economical, has the disadvantage that its motor piston cannot be moved positively or stopped quickly and accurately.

devise a servo-motor system which is partially l hydraulic and partially pneumatic, whereby versatility and satisfactory operation are obtainable at a minimum constructional cost.

It is a further object of this invention to devise a system of the character described in which the initial pressure medium is a compressible uid and is utilized to react upon a liquid for operation of an eXpansible chamber motor. In this connection, it is an important object to maintain the liquid in a closed system including the motor.

Another important object of my invention resides in the provision of controlling devices of novel design and arrangement for coaction with a combination pneumatic-hydraulic system embodying an expansible chamber servo-motor.

The foregoing and other objects of the present invention will clearly appear from the following description when studied in conjunction with the accompanying drawing, wherein the single gure is a somewhat diagrammatic view, chiefly in section, depicting a preferred embodiment of the invention.

The illustrated arrangement comprises a motor cylinder 3 containing a piston 4 having a working rod 5. The motor is conventional and will embody suitable seals and packings, as will also the valve structures later described.

One end of the cylinder 3 is connected through a pair of pipe sections 6 and 'I to a reservoir 8, the latter being nearly filled with an incompressible fluid 9, such as oil, and the pipe I termi- 1 Claim. (Cl. (iO-51) nating near the bottom of the reservoir for purand is rigidly connected to a spool type valve unit comprising three spaced apart and inte- 4 "grally joined cylindrical elements I6, I'I," I8. EX- haust outlets Ig `and '"are vprovided at inter- 15 against leakage. However, as above indicatedAl 20. It is the primary object of my invention to' mediate portionsof the casing.

The spacing andarrangement of the valve parts and pipe connections to the casing I3 are such that the element I6 controls the inlet pipe I2, and theelements I'I and I8 control the exhaust pipes I3 and 2D, respectively. The pipe I0 always is in communication with the space i between elements I6 and I8, and the pipe I4 always is in communication with the space between elements I6 and I1. Y

Interposed between the pipe sections 6 and 1 there is a second valve casing `22 through one end of which slidably projects a valve stem 23 in parallelism with the other valve stem I5. The stem 23 is rigidly united to a spool valve unit comprising three integrally joined cylindrical elements 24, 25, 26. A U-shaped passage 21 in the casing wall is in communication with the pipe section I and constantly interconnects the two spaces formed by the three cylindrical valve elements. The element 24 controls the pipe 6, permitting it either to receive oil from the reservoir 8 or to discharge oil from the motor cylinder back into the reservoir.

The valve stems I5 and 23 have their projecting ends securely connected in any suitable manner to the ends of a bar 28, the latter in turn being rigidly joined to a single operating link 29 through which both valves may be actuated simultaneously. The link lis pivotally connected at 30 to one end of a lever 32 that has a stationary pivot 33 between its ends. The upper end of the lever has a knob or handle 34 which may be manipulated to oscillate the lever in the directions of the illustrated arrows, thus to reciprocate the two internal value units simultaneously in one direction or the other.

It should be understood that the two valve structures and their actuating mechanism may take various other designs, it being essential only that they perform the functions outlined in the following statement of operation.

With the parts positioned as in the drawing, the source of compressed air is cut oi, and both the reservoir and the right hand end of the motor cylinder are open to atmosphere through the outlets I9 and 2G, as shown by the arrows. If the control knob 34 is pushed slightly to the left, both valve units are pulled to the right to permit compressed air to enter the reservoir 8 and to permit -oil to be forced into the motor to drive its piston to the right. .At this time the exhaust I9 is closed, the exhaust 2U remaining open.

Ii the control knob is shifted past neutral to the right, compressed air is 'admitted Yto the motor to force its piston to thelemdischarging oil into the reservoir as permitted by exhausting part of the head of air therefrom through the opened outlet I9. At this time the outlet 20 is closed. In either direction of movement the motor piston may be quickly and accurately stopped in any positionjby 'snapping the control lever back to its illustrated locking or neutral position to cause complete closure of pipe '6 by the oil 'valve element 24; fand for this purpose a spring Varrangerrrent may V'lie 'provided to kick the lever into "neutral accurately upon release o`f the control sknob '3l The lower end of pipe 1 :is kept deeply immerse'd in fthe 'oil jso'that air cannot pass the reservoir. The totalquantity of oil is such that `the reservoir jWill 'bje :full `when the motor piston is in its jextreme jleft hand position, thus precludimg the '-loss di oil "to the atmosphere through the pipes ill, HL

The lleflt en d of the n motor cylinder may be `provided with ja *'bleed'er valve topermit escape of any Aentra'pp'e'dair and to facilitate initial lling of the jpipes r`6 and l withoil. Also, of course, the reservoir 8 will be equipped With any suitable means for Liilling the 'tank and for adding 4oil 3to v'compensate vfor jslight amounts that `may 'escapeint'he form dfvapor orvfne particles.

It Wouldseldom if Leverbe vnecessary to make the motor Acompletely `hydraulic -in 'action but,

if desired, this can readily be accomplished by breaking the pipe line Il) in two places and inserting therein a second oil valve and a second reservoir like those illustrated. The second oil valve would be properly controlled by the stem 2S or by another stem connected to the bar 28.

In special installations, the pipe HJ may be omitted and a compression spring may be placed in the rightend of the motor cylinder, this spring having a constant tendency to return the piston to its left hand position.

Various other changes in arrangement and design of the parts may be made Without departing from the spirit of the invention, all contemplated within the scope of the appended claim.

What is claimed is:

In combination with a closed chamber containing a quantity of liquid never substantially exceedingits full capacity; a motor comprising 'ajcylinderfandip-iston;ja conduit connected from one v'end of said'cylinjder -to said chamber; a stop jvalve in said conduit; 'a valve casing connected to a source of compressed air; separate 'connections `from said casing nto Ysaid `chamber Aand Ito theother end of ,said cylinder; a valve in said casing operable to 'establish communication from said connections 'either ,to -said 'source of compressed air or to the ambient atmosphere; and Ycontrol means common tosaid valves, and socorrelated "therewith that said lchamber and said other end oi saidcylinder 'are ,open `to the atmosphere simultaneously When-"thejiirst-named conduit is vclosed by s'aid stop Valve.

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