US1293858A - Hydraulic valve. - Google Patents

Description

C. A. MILLS.

HYDRAULIC VALVE.

APPLICATION FILED AUG.2.19X8.

B at ented Feb.11,1919.

CHARLES mman OFFICE.-

MILLS, OF SHEFFIELD, ENGLAND, ASSIGNOR T0 DAVY BROTHERS,

LIMITED, OF SHEFFIELD, ENGLAND. I

HYDRAULIC VALVE.

Specification of Letters Patent.

Application flied August 2, 1918. Serial No. 248,082.

To all whom it may concern: 7

Be it known that I, CHARLES Ahme in Hydraulic Valves, of which the followin is a specification.

ydraulic piston-valves of the well-known type wherein the piston or spindle carries a leather packing-ring for the purpose of controlling a port in. the valve-casing, have hitherto suffered from a serious disadvantage owing to the fact that the leather, in passing over the annular or virtually annular valve-port in the surrounding valvecasing, is apt to spread out radially under the hydraulic pressure to which it is exposed, with the result that the leather, becoming wedged into the port, is in time shorn away and the packing is thus rendered useless. The object of the present invention is to overcome this difliculty by providing a construction such that the leather will remain completely inclosed on its outer as well as on its inner surface at all points in its travel, and will thus be prevented from spreading and becoming wedged into the valve-port when passing over the latter.

For this purpose, each leather packingring to which the invention is applied is provided with an inw'ardly-cylindlical movable shield for the reception of the packing-ring during such portion of its travel as extends across the port-opening; the shield, which has the same internal'diameter as that section of the bore of the valve-casing wherein the packing-ring. normally rests, being caused to move asone with the packing-ring only so long as the latter remains completely housed within it, and'being at other times retained by yielding pressure'in position to constitute in effect a continuation of said section of the bore in the Valve-casing.

In a practical embodiment of the invention the shield is movable, lengthwise of the valve-spindle, within a cavity or chamber surrounding the spindle at the side of the port remote from that section of the bore' wherein the packing-ring normally rests;

the shield, when the port is closed and the leather housed in the bore of the valve-casing, being held by spring-pressure in or across the port, while the spindle and shield are adapted to so engage one another when (during the port-opening movement) the leather has passed from the bore of the valvecasing entirely within the shield, that the continued movement of the spindle will cause the shield (with the leather inclosed within it) to be carried past the now open port in opposition to the spring-pressure whereby, on the return or port-closing move- Patented'Feb. 11, 1919.'

ment, the shield is caused to resume its position. in or across the port before the continued movement of the spindle carries the leather out of the shield and into the bore of the valve-casing.

The accompanying drawing, which illustrates one form of valve to which the invention is applied, shows in axial section a pair of single-acting piston-valves (for a ydraulic press or similar hydraulic apparatus) in each of which the leather packingring carried by the valve-spindle is provided with a movable-shield.

The two piston-valves, whereof that on the left of the drawing is the inlet valve and that on the right the exhaust valve, are arranged side-by-side with their axes vertical, within a single casing having a central chamber a through which both valvespindles pass and which is inopen communi-cation with a lateral branch 6 connected with the press cylinder (not shown). Above the chamber a is a port 0 surrounding the inlet valve spindle and in open communication with a second lateral branch (Z connected with the source (not shown) of hydraulic pressure; this inlet port 0 being adapted to be put in communication with the chamber a by way of a vertical bore 0 through which passes the inlet valve spindle. Beneath the chamber a is a passage 6 in open communication with a third lateral branch (not shown) connected with the exhaust;- this exhaust passage 6 being adapted to be put in communication, by way of a vertical bore 7'' through which passes the exhaust valve spindle, with that portion f of the central chamber a which immediately surrounds said spindle and which thus constitutes ineffect the exhaust valve port.

The twovalves are similar in construction, and hence the same description applies equally to either Valve, it being understood that the openin of the respective valves alternatively is eected by means of a cam g on a shaft 9 which can be rocked in either direction at will from a mid angular position so as, while leaving one of the valves resting in the lowered or closedposition, to open the other valve by raising its tappet h and spindle h a ainst the pressure a spring 9 in the wellnown manner. In the drawmg, the left-hand or inlet valve is shown as closed while the shaft 9' and cam' 9 have been rocked so as to open the right-hand or exhaust valve.

The sliding leather is 1n each valve 1s of the'us ual U-shape in cross section, and is held in position against an upwardly presented shoulder Z on the valve-spmdle h by a gland-rin m at the lower endof a sleeve m which, ttin over the spindle, 1s forced toward the shou der Z by means of a cap 12 which is screwed at n over the upper end of the spindle so as to be adapted to receive,

' and transmit to the spindle h, the thrust of ward across the port 0 or f leather is upward wholly within the shield the valve-closing spring j. t The external diameter of each leather is is adapted to fit that section 0' or f of the bore wherelnthe leather rests when the valve is closed as 'show'n in the case of the inlet valve, but out of which theleather is raised entirely when the valve is opened as shown in the case of the exhaust valve; the lips of the U-shaped leather being directed'upward in each case so that the leather will be distended radially b hydraulic pressure when the valve 1s clbsed. The shoulder Z on the valve-sp ndle may fit the bore-section at c or f as 1nd1- cated, but immediately beneath the shoulder the spindle has a portion l of reduced diameter so that, when the leather is and shoulder Z are raised out of the bore, the latter will be open to the port 0' or f as shown 1n the case of the exhaust valve. Each slidin' leather is is provided with a movable annu ar shield o, inwardly cylindrical, which throughout the greater part of its length has the same internaldiameter as the bore-section 0 or fand whichv extends upinto fa chamber 0' surrounding the sleeve m this shield 0 having at its u per end an internal flange p which fits s idably over a portion of the sleeve m having a diameter less than the diameter of the bore 0 or f. Normally (i, e. so long as the valve is closed) the shield o-is held down by a spring 1' so that its flat 'an-. nula'r lower end rests in contact with the level surface surroundinfg the s eld 0 then the u per orifice of the bore-section a or constitutin tion of sai dle It has been raised su virtually an upward continuaciently to-carry the 0, a shoulder s at the lower end of the sleeve m engages the internal flange p on the shield and causes the latter, during the remainder of the upward movement'of the spindle h, to rise as one with the spindle and leather, thus opening the port 0 or f to the bore-section ,0

or f. On the valve-spindle it being allowed to descend under the stress of the spring j,

bore-section but when the spinsurface surroundiiy; the upper orifice of the bore-section a, or afterwhich the spindle h in its further descent to normal osition carries along with it the leather k wh1ch thus passes from within the shield 0 into the boresection 0 or f.

It will be noticed that, in the example illustrated, the leather it rests normally (2'. e. so .long as the valve remains closed) partly in the bore-section c or f the shield 0, into which the lips of the leather are shown as then extending; but it is obvious that the leather might normally rest whollywithin the bore-section c or f with its lips either at or below the level of the upper orifice of the bore. The arrangement shown in the drawing, however, eliminates any possibility of the lips of the leather failing to enter the shield accurately and smoothly during the upward movement of the,valvespindle, while the same time the length of upward tra'vel given to the valvespindle can be made less than would otherwise be necessary.

Theleather 7c is distended by hydraulic pressure which may be allowed to gain access to its inner surface by way of notches on the outer periphery of the shoulder 8 on the sleeve m and corresponding notches on the innerperiphery of the flange p on the sleeve 0, or by other suitable channels.

The shield-spring r is shown as taking its abutment against the lower end-of a gland t wh1ch closes the upper end of the chamber and partly within 0 and serves to hold in position a stationpacked bya stationary U-shaped leather c.

v I It will be seen that the shield 0 has a toand-fro movement of less extent than that of the valve-spindle h and leather is, and

N that, during the port-opening movement, the

leather is cannot emerge from the bore-sect1on 0 or f wlthout having entered the shield; and that conversely, during the postclosing movement, the leather is cannot emerge from the shield 11 without simulta- ,,neously entering the bore-section c or f.

Hence at no point inits travel is the leather k unsupported both externally and inter nally, and consequently the hydraulic pressure, gaining access to the interior of the leather, cannot distend the latter beyond a diameter equal to that'of the bore-section c or f.

In some cases, more particularly where the valve-spindleworks vertically and performs its port-closing movement in the downward direction, the shield-spring maybe dispensed with,'the frictional contact of the leather of the valve-spindle k is c within the shield sufiicing to insure the return of the latter to its seated position in or across the port. In this case the provision of a vent-hole or holes in e. g. the. inwardlyflanged upper end of the shield will insure the shield as a whole remaining in hydraulic equilibrium and devoid of any tendency to leave its seated position so longas the port is closed.

What I claim is 1. In a hydraulic piston-valve of the type referred to, the combination with a leather packing-ring carried by the valve-spindle for the purpose of controlling a port in the valve-casing, of an inwardly-cylindrical movable shield for the reception of said packing-ring during such portion of its travel as extends across the port-opening; the shield having the same internal diameter as that section of the bore of the valve casing wherein the packing ring normally rests, means for causing the shield to move as one with the packing ring only so long as the-latter remains completely housed within :to constitute 1n effect a continuation of said section of the bore in the valve casing.

2. In a hydraulic piston-valve of the type referred to, the combination of a valve casing having a port and provided with a chamber and a bore in axial registry and (a located upon opposite sides of said port, a valve spindle movable lengthwise of said chamber and port, a packing-ring carried by said spindle for controllingsaid port and normally resting in said bore, an inwardlycylindrical shield for the reception of said packing-ring during such portion of its travel as extends across the port, said shield being movable within said chamber, a spring for normally holding the shield in registry with the port, and cooperating means on said shield and valve-spindle adapted to engage each other whereby said shield and spindle are concurrently moved during part of the movement of the latter.

CHARLES ALFRED MILLS.

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