US2303175A - Throttling device - Google Patents

Description

Nov. 24, 1942, 1 H. RUSSELL THROTTLING DEVICE Filed Jan. 24, 1940 Patented Nov. 24, 1942 THROTTIJN G DEVICE Irving H. Russell, Oak Park, lll., assignor to Sloan Valve Company, Chicago,

Illinois lll., a corporation of Application January 24,1940, Serial 1Y0. 315,440

8 Claims.

This invention relates to throttling devices generally, but is concerned more particularly with throttling devices arranged to be self-adjusting to maintain a substantially uniform rate of discharge ilow therethrough in spite of wide varia'- tions in supply pressure. n

The general object of the invention is to provide a new and improved self-regulating throttling Vdevice which can be simply produced and which accomplishes its purpose in a satisfactory and reliable manner.

A specic object is the production of a selfadjusting throttling device of the above character which is compactly arranged and is combined with a valve for desired.

A further object of the invention is to provide for regulating the self-adjusting throttling device as regards the rate of flow for which it adjusts itself, whereby such variations as are likely to result in manufacture are compensated for.

It is a further specific object of the invention to so combine the self-adjusting throttle portion of the structure with the shut-off valve portion of shutting oi the supply when the structure that the essential parts of the selfadjusting throttle portion may be removed from the discharge side of the structure, for inspection, repair, or replacement, with the valve portion in closed position, whereby such inspection, repair, or replacement as is likely to be required may be accomplished while the supply pressure is on.

GENERAL DESCRIPTION It has been chosen to illustrate the invention as applied to a combined self-adjusting throttle toward the discharge end of the casing, and having the controlling parts for the self-adjusting throttle device contained within' this cup. The end of this cup cooperates with a valve seat surrounding the discharge port to act as a shut-olf valve when desired.

The self-adjusting throttle device takes the form of a throttle member normally located at the entrance to the discharge port, extending through the discharge endof the casing, and sel cured on the supporting stem of va spring-restored piston operating within the said cup.

The spring-controlled piston assembly on which the throttle proper is carried is held in place by a retaining' gland threaded into the open end of the valve cup and keyed to the piston assembly so that it can be Unthreaded by turning the piston assembly. This gland, the throttle proper, and the other parts associated therewith are sufliciently small that they can all be removed through the discharge port for inspection or repair when the gland is unscrewed from its normal location within the valve cup.

Since the self-adjusting throttle device, within its operating range, maintains the discharge rate therethrough substantially uniform independent of variations of supply pressure, any change of supply pressure within the operating range of the deviceresults in a corresponding change in the pressure drop occasioned by the throttling action. This principle is availed of in securing the desired self-adjustment. The travelling throttle assembly is exposed on the discharge side thereof to a back pressure which is substantially uniform when there is a uniform rate of discharge through the throttle device, while the supply side of this travelling assembly is exposed to the van'ablesupply pressure. A compression spring which opposes the movement of the travelling throttle assembly in the direction of flow is compressed more or less, according as the supply pressure is higher or lower than a given supply pressure.

A feature of the invention is that the discharge throat is provided with a tapered portion which narrows downsteamward toward a straight por-- tion, and the parts are arranged so that the throttle proper operates within this tapered portion over a large part of the pressure range of the device, whereby the discharge area between the throttle piece and the tapered side walls of the throat decreases as the travelling assembly is driven farther downstreamward by the higher supply pressures. Thus, as the assembly moves I further responsive to higher pressures, the eiective discharge area is progressively decreased in just the measure required to maintain the rate of discharge substantially uniform for all such higher pressures.

A further feature of the invention is that the required range of movement of the travelling assembly is reduced by providing a more abruptly tapered portion for the throat near the entrance thereof, and by providing a second and weaker restoring spring for controlling the travelling assembly in its movements responsive to pressures near the lower limit.

A special feature of the self-adjusting throttle device is that it is so arranged that the flow of-liquid therethrough is accomplished in substantial silence, even when the supply pressure is high. f

The drawing Referring now to the accompanying drawing, comprising Figures 1 to 6, they show sufcient views of the structure embodying the invention to enable the invention to be understood.

Figure l is a vertical section of a combined shut-off valve and self-adjusting throttle embodying the invention, the parts being illustrated in the position they occupy when the shut-oif-valve portion is closed:

Figure 2 is a similar view, partly in section,

I showing the parts in the position they occupy when the valve portion is opened to a working position, but when no i'iow is taking place:

Figure 3 is a view similar to Figure 2, but showing the throttle portion in the self-adjusted position which it occupies when a full throttled flow is occurring from a supply of medium pres- Dumm DEsoaIr'rIoN The invention having been described generally, a detailed description of the disclosure will now be given.

The installation, Figures 4 and 5 Referring now particularly to Figures 4 and 5,

an installation utilizing the improved device of Figures 1 to 3 is illustrated at I therein. Figures 4 and 5 illustrate a flush-valve installatiomfor ilushing a water closet or other receptacle, the rearmost portion of which is indicated at 51 in Figure 4. The supply pipe or nipple 55 is shown as coming through a wall to which the flush valve 53 is attached. The valve and throttle device I has its inlet threaded onto the end of the supply nipple 55, while its outlet is connected by means of the telescoping supply tubes 35 and 5I to the inlet 52 of the iiush valve 53. The outlet of the flush valve 53 is connected through the flush tube 55 to the inlet portion of the water closet or other receptacle 51. The flush valve illustrated is of the push-button type, having the push button 55, an actuation of which causes the flush valve to be opened hydraulically and to reclose slowly to secure the discharge of a predetermined quantity of flushing water. This ilush valve has duplicate inlets, the right-hand one being in use in the illustrated installation, while the unused left-hand inlet is closed by the inlet cap 55.

In the illustrated installation, theportion 51 of the plumbing fixture to -be ilushed is assumed to be the rear or inlet portion of a water closet which is flushed properly when the rate of flow of the water supplied thereto through the flush valve is about twelve gallons a minute. The combined shut-off valve and self-adjusting throttle device shown at I in Figures 4 and 5, andillustrated in Figures 1 to 3, is-designed so as to perform automaticallythe degree of throttling necessary to permit a rate of flow of about twelve gallons a minute through the flush valve and into the water closet 51 when the pressure of the water received through the supply nipple 50 is from about ve pounds to the square inch to, say, one hundred pounds to the square inch. The'well understood advantage of such an arrangement lis that it insures that the rate of delivery of water view of an installation which through the flush valve to the water closet is at or very near the preferred rate of flow (abut twelve gallons a minute in the assumed installation) under a wide range of conditions oi installation and operation. For example, the supply pressure available in the street main may installation and the street main is long and more .or less restricted).

The new and improved self-adjusting throttle device disclosed herein maintains the desiredv discharge rate therethrough and through the ilush valve 53 and into the water closet 51 under the above conditions of variation, as will be explained hereinafter.

The improved construction, Figures 1 to 3 Eportion of the ball-.joint unio including the ball portion 31 afiixed to the tube 35, through which water passing the device is supplied to the nush valve 53 of Figures 4 and 5.

'Ihe cup-shaped control valve I1 is mounted within the casing I, and is provided with an annular beveled seat I5, which is shown seated -around the outlet port in Figure 1.

The bonnet 5 is threaded into the end of the casing opposite the outlet 3, the connection being made water-tight by the sealing gasket 1. To enable the device to be adjusted, the adjusting stem I I is mounted in the bonnet 5 and it extends to the outside of the device, and is provided with the wheel handle I5, by means of which the stem II may be turned as desired. Packing member I2 is held in place by packing gland I3 to prevent leakage around the stem II. The inside end of the' stem II is shouldered as illustrated to retain the stem I I in place against outward force.

The hollow stem 5 is mounted for rotation in the bonnet 5 in alignment with the control stem II, and is held in place by retaining gland 5, in cooperation with the annular shoulder 5 on the hollow stem l5. A transverse key I5, formed onl the inner end of control stem II, nts within a cooperating notch or keyway in the outer end of hollow stem 9 to force the stems II and 5 to rotate together.

The inside of the hollow stem 5 is threaded to receive the outside-threaded stem I5 formed iny tegrally with the cup-shaped shut-oi! valve I1.

Valve I1 is provided with a pair of oppositely disposed lugs I5, through which rotation of valve I1 and the stem I5 are prevented. The lugs I5 operate in a pair of longitudinal slots in the skirt ,portion 5, formed integrally with the bonnet 5,.

such skirt portion 4 being divided into two halves by the longitudinal slots in which the .lugs I 5 body. Two of these guide ribs, 44 and 45, may be seen in Figures 2 and 3, but they are hidden from view by the valve I1, in closed position, in Figure 1. 'I'he dotted line 46 in Figure 3 exemplies the prole of one of these guide ribs.

The self-adjusting throttle portion of the device constitutes a travelling assembly which includes the central stem or piston member 24, located principally within the cup formed within valve I1, but having a forward portion which extends into the discharge port. The stem or piston 24 is provided with a head 2I only slightly smaller in diameter than the cup or cylinder inside the valve I1. Thepacking cup 22 is held between piston head 2l and the loosely fitting washer 23 by spring tension. The serially related coiled springs I9 and 20 exert pressure against washer 23, thereby holding packing 22 in place. At the other` end, the serially related springs I9 `and 20 bear against the retaining gland 25 which is threaded into the cup I1. The reduced stem portion 24 of the piston passes through the central opening in gland 25, a clearance of a few thousandths of an inch being provided to insure freedom of movement and to permit interchange of water through this clearance space.

The gland 25 is provided with an inwardly projecting key 3l which fits within the longitudinal keyway 41 provided in stem portion 24. The piston 24 is thus prevented from turning with respect to gland 25, whereby the gland may be screwed into place and unscrewed by a turning of the piston or stem 24. Such turning is facilitated by the flattened end portion 35 of the stem.

The stem portion 24 is reduced somewhat in diameter slightly above the upper end of gland 25, forming .a shoulder against which washer 26 lies. The throttle proper. composed of parts 21, 28, and 29, is assembled adjacent washer 26, and is held in place by the retaining nutv 30.

'Ihe throttle piece includes the metal insert 28, the covering 29 of woven-wire mesh which is stamped and draw-formed into a tight covering for insert piece 28. This woven-wire covering is drawn in andfolded down at the underside of the throttle member, and is partially pressed into the lead washer 21 to hold it firmly in position.

The annular impact member 32 is provided for y lower end of the union ball 31.

The throttle piece 29 and the impact member 32 are included in the subject matter and claimed in the copending application of William E. Sloan, Serial No. 320,789, filed February 26, 1940.

Operation The operation of the improved device will now be described. It may oe assumed that the device is installed as illustrated in Figures 4 and 5, and that it is installed in itsclosed-off position, illustrated in Figure l.

"Blowing out the piping After the installation is made, and the supply pressure has been applied to the'supply pipe 58 (Figure 4), the handle I4 is turned slowly in such a direction that the resulting turning of stems I I and 9 results in a lowering of the non-rotating stem I5 and the resultant lowering of the valve I1. The seat portion I8 is thus brought down from its seated position around the discharge orice. This opening of the valve I1 admits the supply pressure to the inlet of the flush valve 53, but no more than a momentary ilow may take place until the ilush valve 53 is tripped.

The opening operation is continued until the valve I1 reaches its most fully open position, the movement being stopped when the lower end of valve I1 comes against the opposed face of the bonnet 6.' In the illustrated embodiment, the total opening movement is approximately sevensixteenths inch. 'I'he opening movement carries lthe self-adjusting throttle device further away from the discharge port than -its normal working position, whereby a rate of ow much larger than the working rate of flow may be obtained through the piping system to enable any loose debris that may be contained therein to be washed out.

The flush valve 53 isnow actuated one or more times (by tripping the button 54). This operation is known as blowing out the piping, for

Setting the device in its working position After the supply piping has been washed free of debris as above described, the handle I4 may then be turned in the opposite direction about one full turn to thereby move the valve I1 and the self-adjusting throttle assembly carried thereby about one-eighth inch back toward closed position, being about the position in which the device is shown in Figure 2. The throttle 29 is thereby advanced suiiiciently far into the entrance of the discharge port that it is in a position to be forced further into the discharge port when the rate of flow substantially exceeds the preferred value, about'twelve gallons a minute in the assumed example.

Low-pressure operation Assuming now that the supply pressure is sufiiciently low, with respect to the length of the supply pipe 50, of Figure 4, that the rate of flow does not rise above the preferred value when the flush valve. 53 is tripped by the push button 54 to cause the water closet 51 to be iiushed, the pressure drop through the annular throat defined by the throttle 29 and the discharge port is suiliciently small that the piston which carries the throttle 29 is not moved against the tension of compression springs I9 and 42li. 'I'he device, therefore, remains in the comparatively unthrottled position illustrated in Figure 2. to permit the maximum flow to occur under the assumed conditions. During the flow under this assumed condition, the pressure existing at the inlet 2 of the device is comparatively low.

Medium-pressure operation Let it be assumedy now that the supply pressure is sumciently high, with respect to the length of the supply piping, that the rate of now, unless additionally throttled by lthe illustrated device, would substantially exceed the preferred rate of flow of about twelve gallons/ a minute. Under this condition, when -the flush valve is tripped and the flow starts and rises to andl tends'to exceed the preferred value, the self-adjusting throttle assembly begins to move with the current against the tension of restoring springs I9 and 20. This movement occurs because the rate of flow then occurring is accompanied by a sufficient drop in pressure of the water in flowing around the throttle device 29 that the back pressure exerted against the downstream side of this throttle device is substantially lower than the pressure existing at the inlet 2 and on the upstream side of the self-adjusting throttle assembly.

The pressure existing on the upstream side of the throttle 29 is extended to the interior of the cup valve II and around the stem 24 of the piston, by way of the annular space between the inside diameter of the retaining gland 25 and the outside diameter of the stem 24. The pressure existing around the stem 24 is further extended through by-pass opening 39 (see Figures l and 6) to the hollow interior of the stem 24 and thence to the space between the end of the piston and the end of the cup or cylinder in which it operates. It will be noted that a shallow depression is milled in the end of the piston head 2|, leaving an annular contact rim. This rim is broken at the groove 4I! (Figure 1) to permit the pressure within the hollow interior of stem 24 to pass freely through the gap 40 to thus be exerted over the entire area of the enclosedend of the piston.

As illustrated, the compression spring 25 is made of round stock (stainless steel wire, for example) and is comparatively powerful. On the other hand, the shorter spring I9 is made of fiat stock (stainless steel strip, for example) and is a comparatively weak spring. As a result, very little compression of the strong spring 20 occurs when the movement of the self-adjusting assembly is comparatively small, for nearly all of the movement then occurring is represented by compression of weak spring I9. For those low-inlet pressures just above the minimum, a comparatively large movement for each unit of increased inlet pressure occurs because spring I9 is comparatively weak.

The weaker spring I9 permits a comparatively large movement of the self-adjusting assembly responsive to a comparatively small pressure drop through the annular throttling throat at the lowlpressure end of the range, where a small pressure change is a. comparatively large proportion of the total existing pressure and, therefore, requires a comparatively large change in the amount of throttling to maintain the now uniform.

As successively greater inlet pressures are encountered, requiring successively greater movement of the travelling assembly, the position is soon reached at which the weak spring I9 makes solid," that is, becomes fully compressed. After this occurs, each further unit of increased inlet pressure results in less movement of the travelling assembly because all further movement is ciently great to cause enough movement to compress the spring I9 completely and to substantially compress the stronger spring 20.

Assuming now that the supply conditions are such that the medium inlet pressure exists during the preferred rate of flow which requires adiustment of the travelling assembly to the working position illustrated in Figure 3, the movement of the device from the normal position illustrated in Figure 2 to the medium-pressure working condition existing in Figure 3 will be explained.

When the flush valve 53 of Figures 4 and 5`is actuated by a pushing of the button 54 under the assumed conditions, the flush valve 53 opens hydraulically in the usual manner to permit the desired discharge of water to occur.' As the flow increases upon the opening movement of the flush valve, the pressure diierential across the throttle piece 29 exceeds the restoring force of the weak spring I9, whereupon the self-adjusting assembly m`ove`s upwardly with the current to fully compress spring I9. To avoid overthrow of the travelling assembly and a consequent jumpy operating movement thereof during the ensuing flushing operation, the movement of the travelling assembly is damped by the disclosed piston-cylinder couple or dash-pot. The packing cup 22 makes sealing engagement with the associated cylinder wall to prevent water from flowing between the piston and the inside wall of the cylinder. The water can thus flow behind the moving piston only as fast as it can flow through the small by-pass opening 39, the preferred size of which is about one-sixteenth inch diameter.

Under the assumed condition, movement does not stop upon the complete collapse of weak spring I9, but continues to compress the stronger spring 20 until the travelling assembly reaches the position illustrated in Figure 3.

When the flow decreases and stops, as the ush valve 53 recloses, the travelling assembly slowly returns to the normal position illustrated in Figurev2.

High-pressure operation The operation of the device under a condirate of ow is occurring, is the same as described previously, except that the pressure differential across the throttle 29 is sufiiciently higher that the spring 20 is compressed still further, and the throttle 29 is moved still further into the narrowing discharge port. The particular device illustrated is designed for a maximum pressure of about one hundred pounds to the square inch. When this pressure is applied to the inlet during a iiushing operation, the large pressure differential then existing across the throttle 29 causes the travelling assembly to be driven into the inlet port until the forward end of throttle 29 passes into the straight portion 43 and closely approaches the upstream side of the silencing impact member I2.

asoaivs Shaping the discharge port From the preceding description, it will be seen that, with a uniform discharge pressure during the preferred rate Iof flow (about four pounds to the square inch in the assembled example), the serially related compression springs I9 and 20 yield collectively an amount in each case, depending upon the amount by which the inlet pressure exceeds the discharge pressure after the self-adjustment has been accomplished. Keeping in mind that the calculation of the rate of flow passing through a variable orice and resulting from a varying pressure differential is affected by many factors other than the net area through the orifice, the shape of the discharge port which gives the most uniform re'- sults over the entire pressure range is best obtained in each separate design by what is usually termed trial and error. vIn this type of device, it has been found that the amount of movement of the self-adjusting throttle resulting from a given presure differential is substantially independent of the effective area of the discharge orifice, and consequently independent of theresulting rate of flow. That being the case, in deumn gives the resulting rate of flow in gallons per signing a device of this sort, an effective procedure is to provide a trial discharge port and note for each selected applied pressure differential the position assumed by the throttle within the port and the rate of ow occurring in such position. For any of these determined positions,

if the rate of ow is higher than desired, thel surrounding wall of the discharge port may be brought inwardly to thereby reduce the discharge area effective at that position of the throttle. On the other hand, if the rate of ow is too low at any determined position of the throttle, the associated surrounding portion of the discharge port may be suitably enlarged to thereby provide the desired increase in the rate of flow for the concerned determined throttle position and the accompanying pressure diierential which causes the throttle to assume this position.

For the illustratively assumed purpose, it was found that a comparatively simple and easily produced shape of discharge port servesv to give regulation within the working limits of the installation over the required pressure range. The following table gives the observed operation of the improved device in the illustrated installation for inlet pressures ranging from one hundred pounds to the square inch down to ve pounds to the square inch:

The first two columns of the above tablegive the pressure at the inlet and at the outlet, respectively, of the self-adjusting throttle device, the pressures being indicated` in pounds to the square inch; the third column gives in sixtyyco fourths-0f an inch the amount of movement of the travelling assembly incident to self-adjustment at the given pressures and the fourth colminute for each of the applied inlet pressures given in the first column.

The above tabulated results were obtained with the illustrated contour of discharge port. This discharge port includes the cylindrical upper section 43, about a quarter inch in length; the tapered section 42, about a quarter inch in length, and having a taper of about two degrees on a side; and the curved entrance portion which has a radius of curvature of about five thirtyseconds of an inch.

As will be noted from the preceding description and from the data given in the above performance table, the adjustable throttle 29 cooperates w.th the curved entrance portion 4I for low pressures; cooperates with the two-degree-tapered portion 42 for intermediate pressures; and cooperates wth the cylindrical portion 43 for high inlet pressures.

Inspection under pressure When it becomes necessary or desirable, the travelling assembly can be removed for inspection while the supply pressure is on. For this purpose, the handle I4 is turned to close the valve I1 so that the seat |8- carried thereby makes sealing engagement around the discharge port as shown in Figure 1. The valve I1 being an imperforate cup, no flow can then take place through the device.

The discharge tube 38 and union ball 31 can then be removed by removing the union nut 36. The impact or ushion assembly 32 enclosed in casing member 344 is next removed, following which the flattened stem portion 35 of stem 24 is turned to unscrew the retaining gland 25 lfrom the valve I'I. It will be recalled that the internal lug or key 3| of the gland 25 lies within the keyway 4l in stem 24 to force the gland 25 to rotate with stem 24.

When the gland 25 has been unscrewed, the entire self-adjusting assembly may be removed through the now unobstructed discharge port. This self-adjusting assembly, when removed and rotated ninety degrees about its longitudinal axis from the position shown in Figures l to 3, appears as illustrated in Figure 6. The assembly shown in Figure 6 may be taken completely apart by simply removing the retaining nut 30.

By the above-described feature, the self-adjusting throttle assembly may be removed for inspection or repair with the associated stop valve closed olf, thus enabling the self-adjusting throttle assembly to be inspected, repaired, or completely renewed if desired, without shutting the water 0E from other fixtures, as would be required if the entire valve assembly had to be taken apart by removing the bonnet member 6.

The previously described feature enabling the device to be opened further than the working position illustrated in Figure 2 for the purpose of securing large rates of flow right after installation to blow out the supply line, operates also to enable adjustment to be made to compensate for variations in manufacture. For example, if

the manufacturing variations are such as to.

' turing variations are in the opposite direction,

set in its expected working adjustment, then the adjusting handle can be turned to withdraw the throttle piece 29 correspondingly further out of the discharge port.

What is claimed is:

l.- In a valve structure, a valve casing including an inlet and an outlet interconnected by a flow passageway, a valve within said casing adjustablebetween an open position and a closed position in ywhich it closes said passageway, said valve having the form of a cup aligned with said passageway, a self-adjusting throttle controlling the ow through the passageway when the valve is in its open position, and means within said cup for stabilizing the adjusting action of said throttle, said stabilizing means comprising a piston slidably arranged within said cup valve and having a hollow stem provided with means for restricting` liquid owfrom one side of said piston to the other, said throttle being supported upon said piston stem, and means for pre-Y venting relative rotation between said cup valve and said piston.

2. In a combined shut-off valve and throttle, a casing having a plug. removably connected therewith, the inside end of said plug' carrying a cup disposed longitudinally of said plug, a

shut-off valve having the form of a cup aligned with the first-named cup, means including a stem working within said plug for telescoping the cup valve more orless within the firstnamed cup to open and close the shut-ofi valve,I cooperable means on both of said cups for preventing relative rotation of said cups while said shut-olf valve is being opened and closed, and a throttle device including a portion telescopable a variable amount within the valve cup to.

eect a variable throttling while the valve is in open position.

3. In a self-adjusting throttle, a casing having an inlet and an outlet in communication with each other through a throttle port, a throttle movable into said port under the influence of an occurring flow, two serially related springs for limiting the extent of movement of said throttle according to the pressure differential accompanying the flow and for restoring said throttle when the ilow subsides, one of said ,springs being comparatively weak, both springs being eiective to permit movement of the throttle by their combined flexibility responsive to comparatively small pressure differentials, and vmeans for controlling further movement of the throttle, responsive to higher pressure diieren- 'tials, according to the lesser flexibility of the stronger spring.

4. In a self-adjusting throttle, a casing having an inlet and an outlet in communication with each other through a throttle port, a vthrottle movable into said port under the influence of an occurring ow, and a weak spring and a v strong spring serially related to variably oppose the said movement according to the extent thereof. l

5. A unit-replaceable assembly for a self-adjusting throttle device including ,a throttle-control piston having a piston head, a screw-threaded retaining gland surrounding said piston and slidable longitudinally thereon, said gland and piston being keyed to prevent relative rotation thereof, a restoring spring surrounding said piston between the head thereof and the retaining gland, a throttle secured to and carried by said piston beyond'said retaining gland, and a 'portion extendingggbeyond said throttle enabling said piston to be turned thereby to turn said screw-threaded retaining gland into and out offassembled position.

6. A unit-replaceable assembly for a self-adjusting throttle device including a throttle-control piston having a piston head, a piston-retaining gland surrounding said piston and sudable longitudinally thereon, said gland being adapted to be secured in and loosened from assembled position responsive to rotation thereof, said gland and said piston being keyed together to prevent relative rotation thereof, a throttle secured to and carried by said piston, and means facilitating the turning of said piston to thereby turn said gland to secure it in and loosen it from assembled position..

7. In a combined fluid shut-on valve and throttle, a casing having a chamber therein and a bonnet closing one end thereof, inlet and outlet passages in said chamber, saidoutlet passage having a valve seat therein, a 'cup-shaped valve in said chamber, adiustment means extending through said bonnet for adjusting said valve into open and closed position with said seat, cooperative means between said valve and said bonnet for preventing axial rotation of said valve as it is adjusted, and self-adjusting throttle control means located within said cup-shaped valve comprising a piston head slidable within said valve andjiaving a stem portion extending outside said valve into said outlet passage, a throttle member supported on the piston stem in said outlet passage and located down-streamward of said valve seat, a retaining gland surrounding said piston stem and closing the open end of said valve, cooperative means between said retaining gland and said piston stem for preventing axial rotation of said piston, and a throttle control spring surrounding said piston stem and extending between said retaining tle control means located within said cup-shaped valve comprising a piston head slidable within said valve and having a stem portion extending outside said valve into said outlet passage, a throttle member supported on the piston ste'm in said outlet passage and located downstreamward of said valve seat, a retaining gland surrounding said piston stem and closing the open end of said valve, cooperative means between said retaining gland and said piston stem for preventing axial rotation of said piston, a throttle control spring surrounding said piston stem and extending between said retaining gland and said piston head, and a stabilizing means dor said throttle comprising restricted passages extending between said retaining gland, said piston stem and'said piston head.

IRVING H. RUSSELL,

Images