US2082613A - Hydraulic operating mechanism - Google Patents

Description

June `1, 1.937.` G. w. BowER HYDRAULIC OPERATING MECHANISM 'Filed Aug. 3, 1934 Firgl.

Invent oT` George W. Bowen torneg.

J equallzing means arranged to prevent leakage of Patented June l, 19.37

UNITED STATES 2.082.613 HYDRAULIC OPERATING MECHANISM George W. Bower, 'Wesleyville, Pa., .assignor to General Electric Companna corporation 'of New York Application August 3,1924; Serial No. '138,242'V s animalier. en -52) My invention relates to hydraulic operating mechanisms of the type provided with `a piston and has for an object the provision of pressure the operating iiuid from the mechanism.

Heretofore hydraulic operators of the type shown in patent application Serial No. 708,637, McNairy, tiled January 27, 1934, now PatentV No. 11,072,481,v issued March 2, 1937, entitled Hy- '1 draulic operating mechanism for circuit breakers and the like, and assigned tothe same assignee as the present invention, have been used to reset circuit breakers, After the hydraulic operator has closed or reset the circuit breaker, a large valve opens permitting the'quick return of the operating piston. A pressure greater than atmosf pheric pressure is thereby generated in the cylinder causing leakage oi? a mixture offentrapped air and oil around the piston and the pump shaft. I

In carrying out my invention in one form thereof, I provide an attachment for equalizing the pressure within the cylinder with the atmospheric pressure outside of the cylinder. More specifically, I provide an auxiliary oil chamber and an automatically operated valve for venting the cylinder through the chamber to thel outside atmosphere while separating the leakage oil from the mixture of oil andair and returning the oil to the cylinder.

For a more complete understanding of my invention, reference should now be had to the drawing wherein I have shown in Fig. 1 a sectional elevation of my invention applied to a hydraulic operator; Fig. 2 is an enlarged sectional elevation of an attachment embodying my invention; Fig. 3

isa fractional sectional elevation taken on the lines 3-3 of Fig. '1, while Fig. i'illustrates diagrammatically the hydraulic operator with my /attachment applied to it. l

Referring to the drawing, I have shown my invention in one. form as applied to a hydraulic operator It `provided with acylinder II within` which is slidably moimted a piston I2 connected by piston rod I4 to an actuating plate I5 located on the outside of the cylinder. A coil spring I6 strongly biases the piston to one position, the

piston being operable upwardly against the bias of the spring I6 by means of a pressure producing device shown as a gear pump I3. The gear pump is driven byan electric motor (not shown) conthe upper face I2a. of th'e piston I2 against the face v25'of a bypass valve'26. As the pressure builds up against the bypass valve 26 it is operated against the bias Vof a spring 2l to close a bypass 'channel 28 extending on opposite sides of the directly to that part of the cylinder located below the face 12b of the piston I2. As' the hydraulic pressure is increased by the gear pump the piston I2 is operated against the bias of its spring I8 upwardly, the actuating plate I5 being moved thereby into engagement with a switch actuating member 32, which member can be used to reclose a circuit breaker or' for any other purpose. As soon as the piston. reaches apredetermned second position, the rotation of the shaft 20 is interrupted by the deenergizatlon of its driving motor. The motor can be deenergized either by a limit switch or by a manually operable switch. neither being shown in the drawing. As soon as the gears 22. and 23 are brought tol a standstill the pressure against the lower face I 2b of the piston immediately drops to zero. 'I'he spring 21 thereupon quickly accelerates the valve 26 to the position shown in Flg. 1, opening the bypass A channel 28. At the same time, the spring I6 acting against the upper face I2'a of the piston imma-,

, diately accelerates the piston towards itsoriginal position.

oil from below the piston I2 rushes through the bypass channel 28 to the upper side of the piston. 'I'he resulting turbulence and the stirring causes the oil to foam and to ll the space adjacent the upper end of the cylinder with a iiuid mixture of oil and air. Since the pistonrod moving into the cylinder occupies a substantial proportion of the volume within the upper portion of the cylinder, the foam or fluid mixture of oil and air is subjected to a pressure. This pressure is produced because for a given transfer of oil from the'lower to the upper side of the piston due toyrovement of the piston, the increase of volume above the piston is less than the decrease in the volume below the piston. The differencefbetween the two volumes-the volume of the .additional portion of the piston rod introduced into the cylinderbeing taken up by the compressionoi the iluid mixture.

Heretofore the pressure was released by the flow of the fluid mixture around the piston rod Id through its guide, bearing A36 to the atmosphere.

VThis iiow has not only been undesirable but has made necessary periodic replenishment of the I5 `-oil supply within the cylinder. There was also some leakagel oil which escaped'through the housing 31 provided around the pump actuating shaft 2'0.

In accordance with my invention pressure in the upper portion of the cylinder is immediately relievedthrough an inlet opening 40 located on the upper end 42 of the cylinder Il and permitting a flow of the uid mixture of air and oil from the cylinder into' a container mounted on the cylinder'by screw-threaded engagement of its lower end 45 with the cylinder. A valve 46 mounted adjacent the inlet opening 40 is guided for movement between predetermined positions by a valve stem 41 which slidably engages the walls of the passageway 48 extending between opposite ends of the container 44; An opening 43 connects the passageway 48 to the upperend 56 of the container while aplurality ofapertures connect the lower end 52 of the container to a passageway 53 of larger diameter than the valve stem 41 so that oil can iiow through this passageway 53 from the container to the cylinder,

, openings 54 being provided in the valve 46 to per- 'perm1ts the free now or uuid in the farm of ou 40 to the cylinder Ii.

mit. the return of the oil around the (valve.

- Whenv pressure exists within-l the upper portion ofthe cylinder, however, the valve46 vis actuated upwardly from thevposition shown to a second position in which the valve 46 seats against the surface 56 and thereby closes the passageway 53.

A ductforpajssageway 53 provided through the central -portion of the valve 46 and its stem 41 ioamirom the cylinder through the passageway 48 and theopening 49 to the container 44. The sharp right-angle turn provided bythe opening 49 between the passageway 43 and the upper end 50 of the chamber abruptly changes the direct tion of'travel of the iluid sc that the liquid oil collects on the bottom of the container while the air is exhaustedtoatmosphere throughv an outlet 60 formingl a vent at atmospheric pressure.

I have found that bythe time the uid mixture `reaches the lower portiono! the container the liquid and gaseous portions haveso far separated that Ano perceptible quantity of liquid is carried to the atmosphere.

As soon as the pressure within the cylinder is relieved, thel valve 46 operates by gravity to its firsty position, permitting the return ilow of the oil which has been trapped in the container 44 to iiow through the apertures 5i, the passageway 53, and around the openings 54 through the inlet Since the duct 56 is relatively large as compared with the opening around the piston rod I4 and the opening around the driving shaft 20. I have found that the pressure in the `upper portion of the cylinder is diminished so rapidly that no leakage occurs around either the piston or the driving shaft. Consequently, the annoyance of leakage is entirely eliminated by my pressure equalizer and no liquid losses occur since all of the liquid is returned to the cylinder.

said piston, comprising a container provided with inlet and outlet pasageways, said inlet passageway connecting the container to the opposite side of said piston and said outlet passageway forming a vent at atmospheric pressure for said container, a connecting passageway, i'ormed so as to change abruptly the direction of ow between said inlet and outlet passageways and thereby permit the escape oi gas but preventing escape of said fluid from said container, and a pressure operated valve in said inlet passageway normally permitting a return ilow of liquid from Baidjcontainer and operable in response to press atmospheric pressure ior preventing `the return now of liquid from' said container, said valve including means for connecting at all times said inlet passageway and said connecting passage- Way.

2. Pressure f equalizing means comprising 'a casing provided with an inlet and a .vent to the atmosphere, normally open valve means connecting said inlet4 with said casing, said valve means having a passageway at all times connecting said inlet with a remote portion ci said casing, and means within said casing forming a restricted flow path from said passageway for changing abruptly the direction of said flow path, said normally open valve means being movable to a closed position in response-to the pressure at said inlet to restrict to said passageway the flow path from said inlet to said casing.

3. Pressure equalizing means for hydraulic operators provided with a cylinder and pistonl mounted therein, comprising a container, walls forming a passageway extending substantially between the ends ofI said container and open at opposite ends of said container, an inlet between one end c! said container and said cylinder, a valve slidably mounted in said passageway operable between predetermined positions for opening and closing said inlet, said valve having -a duct providing at all times a ilow path from said cylinder to said passageway, said container being provided with `an outlet remotely located from said inlet and opening to the atmosphere.

4. Pressure equalizing means for hydraulic 0perators provided with a cylinder and a piston comprising an'oil-receiving container, an inlet from said cylinder to" one end of said container,

walls forming a passageway from said inlet to the opposite end of said container, said opposite end o`f said container being provided with an outlet opening to the atmosphere, a valve guided by said passageway for operation between predetermined positions, said valve being providled with a conduit for connecting at all times said container to said passageway, said valve being operable by pressure within said cylinder for closing said inlet to restrict ilow of iluid iron' said cylinder to said container through said passageway.

5. Pressure equalizing means for preventing the ilow of leakage liquid from a hydraulic operator provided'with a cylinder, a piston, and

a. piston rod extending through the walls of said cylinder comprising, a container provided with a passageway open at opposite ends of said container, an inlet connecting both said container and its passageway to said cylinder, a valve operable by pressure in said cylinder from one position to a second position for connecting said' inlet to said passageway only, and when in said ilrst position connecting said inlet to both said passageway andsaid container. whereby pressure within "said c'ylindeiis quickly exhaustedzto aosaers 3 said casing, means within said casing i'orminga restricted iiow path from said passageway for changing abruptly the direction oi said ow "path, and an additional passageway normally connecting said casing to said inlet, said valve being operable to close said additional passageway and restrict thereby said iiow path tosaid passageway provided ln said valve means.

GEORGE W. BOWER.

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