US2754842A

US2754842A - Pressure responsive pop valves

Info

Publication number: US2754842A
Application number: US295397A
Authority: US
Inventors: Hagiwara Noboru
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-06-25
Filing date: 1952-06-25
Publication date: 1956-07-17
Anticipated expiration: 1973-07-17

Description

y 7, 1956 NOBORU HAGIWARA 2,754,842

PRESSURE RESPONSIVE POP VALVES Filed June 25, 1952 3 Sheets-Sheet 1 IN V EN TOR. "4301(1) 1996/ 04:0

IIGENTIi United States Patent 2,754,842 PRESSURE REsPoNsIvE PoP VALVES Nbhtiru' Hagiwar'a, Nishin'omiya-shi, Hyogo-ken, Japan Application June 25, 1952, Serial No. 295,397 2 Claims. or. 137-470 The present invention relates generally to improvements in safety valves.

An object of the present invention is to provide an improved safety valve having sensitive and exact operating characteristics. Another object is to provide an improved safety valve which is reliably durable.

The above, and another objects, features and advantages of the invention will be apparent in the following description of a specific embodiment of the invention, particularly when the description is read in connection with the accompanying drawings, forming a part hereof, and wherein:

Fig. l is a vertical, sectional view of a valve embodying the invention;

Fig. 2 is a fragmentary sectional view showing a portion of the structure of Fig. 1, but on an enlarged scale and with the valve in its opened condition; and

Fig. 3 is a fragmentary sectional view, on a greatly enlarged scale, to show the clearance between two relatively slidable parts of the valve.

Referring to the drawings in detail, the valve embodying the present invention is there shown to define a downwardly opening, circular vortex chamber a formed between an outwardly facing peripheral shoulder g on the downwardly facing or lower surface d of a main valve disc b and the lower portion of the inside surface h of a guide cylinder 0 in which the disc b is vertically movable. The guide cylinder 0 is externally threaded, as at f, and is thereby screwed into a cover e so that the lower edge of the cylinder c is located below the downwardly facing surface a of the'main valve disc b when the latter is in its opened or raised position (Fig. 2). A back pressure chamber i is defined within a cylindrical extension projecting upwardly from the main valve disc b, with the back pressure chamber i being closed at the top by the roof of the cover 2. An exhaust opening 1 communicates the chamber i with the atmosphere, and exhaust through the opening 1 is adjusted by a throttle valve k.

Sufficient clearance in is provided between the inner surface of guide cylinder 0 and the periphery of the main valve disc b to permit free sliding motion of the latter within the guide cylinder. For example, a usual free sliding clearance of 0.004 to 0.008 inch may be provided between the surfaces of the guide cylinder 0 and the main valve disc b. A portion 11 of the clearance m is radially enlarged to define an annular space within which an impact sleeve 0 is slidable. The impact sleeve is formed with relatively thick portions 0 at the opposite ends thereof to slide upon te inside surface of guide cylinder 0. The impact sleeve 0 is axially shorter than the radially enlarged portion n of the clearance in to permit the axial reciprocation of the impact sleeve within the enlarged portion 11 of the clearance m. A shock receiving flange p is provided on the upper end of the extension of the main valve disc b, and the flange p extends radially outward, as at q, beyond the outer surface of extension j to overlie the path of travel of the impact sleeve 0 and to be engaged by the latter when the impact sleeve is moved upwardly.

An interior valve seat r is mounted below guide cylinder 0 and in axial alignment with the latter, with the top ri C6 2. surface of valve seat r having an upwardly open, circular vortex groove s therein.

A main valve lift restrainer t is formed with an up wardly directed boss w which is threaded into the roof ofthe cover e and secured against rotation relative to the cover by a stud bolt x. The boss w is formed with an axial bore it having circumferential grooves u in the surface thereof. A valve stem v slidably extends through the bore u, and lugs y extend downwardly from the restrainer t a distance suflicient to contact the shock receiving flange p when the main valve disc b is raised, as in Fig. 2. A washer 5 (Fig. 1) is fixed on the valve stem v and has a semi-spherical top surface 4. A spring receiver 111 is mounted loosely on the valve stem v under a helical compression spring 3, and the spring receiver is formed with a concave lower surface to ride or rest against the surface 4 of washer 5'.

An adapter 6 is detachably mounted on the lower end of valve stem v, the lower end of the adapter being convex, as at 6'. A receiver 8 is mounted centrally on the top side of main valve disc b within chamber i and is formed with an upwardly opening concavity d to receive the convex lower end 6 of the adapter on the valve stem.

The operation of the illustrated device embodying the present invention will now be described in detail:

When high pressure steam flow through an inlet 10 opening centrally through the valve seat r, the main valve disc 11 is pushed upwardly by the force of the steam. As soon as the upward pressure exerted by the steam has become greater than the downward pressure exerted by the spring 3 and the weight of the main valve disc b and associated parts, the main valve disc is lifted slightly. Such lifting of the main valve disc permits the steam to flow radially outward through the passage 11 formed between the bottom surface of main valve disc b and the valve seat r, so that the steam gushes out into the vortex groove s in the top surface of valve seat 1' to form a vigorous vortex ofhigh pressure steam throughout the groove. As a result of this vortex action, the lifting power of the main valve disc b is substantially increased so that the valve opening is rapid and sensitive.

At the same time, aportion of the steam flowing radially outward through the passage 11 passes into the clearance in between the guide cylinder c and the main valve disc b, and in flowing through the clearance acts against the bottom surface of the impact sleeve 0 to raise the latter relative to the main valve disc b. As a result of this action, the impact sleeve 0 is lifted more rapidly than the main valve disc b and vigorously strikes against the bottom surface q of the shock receiving flange p. Thus, the valve opening action of the main valve disc b is assisted by the impact sleeve 0 striking against the flange p. Because of the action of the impact sleeve 0 together with the action of the vortex groove s, the safety valve embodying the present invention operates rapidly and sensitively.

When the main valve disc b has been lifted by the pressure of the steam in the manner described above, the steam is exhausted through an annular exhaust opening 12 defined between the lower end of cylinder 0 and the periphery of the valve seat. During exhaust of the steam, a vortex is continuously produced at the periphery of the bottom of the main valve disc b in the vortex chamber a. The pressure within the vortex chamber a is much greater than the pressure of the steam being exhausted through the opening 12, where the escaping steam being expanded, necessarily experiences a drop in its pressure, and has little effect upon the pressure at the inlet 10 while the main valve is opened. The high pressure produced in the vortex chamber a results from'the fact that, when the valve disc b is raised, as shown in Fig. 2, the lower end of the guide cylinder extends below the bottom surface 0! of the valve disc and is impinged against by the radially outward flowing steam. Since the pressure in vortex chamber a is much higher than the pressure in the enlargement n of the clearance m, the high pressure steam flows upwards from the vortex chamber a into the back pressure chamber i through the clearance m. Thus, the inside or top of the main valve disc b is subjected to the steam pressure when the steam has entered the back pressure chamber i through the clearance in. Because the upward force exerted by the steam within back pressure chamber i is resisted by the fixed cover e, the steam pressure necessarily acts downwardly against the valve disc b. Therefore, the opening and closing action of the valve is rapidly efiected. The back pressure for closing the valve may be easily adjusted by manipulation of the throttle valve k which controls the rate at which steam may be exhausted through the port 1 from the back pressure chamber i.

Further, in a valve embodying the present invention, at the end of the downward stroke of the main valve disc b in response to the decreased pressure of the steam passing through the inlet 10, the steam filling the enlarged portion n of the clearance under the impact sleeve 0 is suddenly sucked out to the exterior through the annular opening 12 by the action of the steam pufiing to the exterior through the passage between the valve seat r and the main valve disc I). The sudden removal of the steam from the enlarged portion n of the clearance m causes the impact sleeve 0 to drop rapidly so that the shutting action of the main valve disc b is assisted and accelerated by the shock resulting from contact of the downwardly moving impact sleeve 0 with the bottom shoulder of the clearance enlargement n. Therefore, the downward action of the impact sleeve together with the aforementioned action of the back pressure chamber i prevents any lag in the shutting action of the main valve so that the pressure in the associated vessel or container is returned to the desired level, but not below the latter.

When the length of the lugs y extending from the restrainer t in accordance with the present invention are properly selected, the position where the shock receiving flange b comes in contact with the lugs corresponds to a predetermined opening of the valve disc. Accordingly, it is possible to properly determine the quantity of steam to be expelled from the interior of the safety valve. Further, it has been found that, when the safety valve is supported only on the tip of the valve stem v, as in previously proposed constructions, the main valve disc b is rotated when raised due to the vortex thereby abrading or causing wear on the adapter. According to the present invention, the rotation of disc b, when it is raised, is avoided due to the pressure of the contact between flange p and lugs y of the lift retainer it so that wearing of the

contact parts

6 and 8 is held to a minimum. Since the adapter 6 is detachably mounted on the lower end of valve stem v and is made to contact the receiver 3, all difiiculties resulting from improper contact of the contact parts, the eccentricity of such parts or the inclination thereof are eliminated. Therefore, the proper spring action is continuously achieved and the operation of the valve is reliable. Since materials having exceptional hardness and resistance to abrasion may be employed for the adapter 6 and the receiver 8, these contacting parts may be made substantially impervious to abrasion or wear. Since only the

parts

6 and 8 need to be replaced when they are worn, the operation of the valve can be ensured for long periods of time without requiring the replacement of any major components of the valve assembly.

Further, since the spring receiver 111 has rocking contact with the surface 4 of the washer 5, even if the spring 3 acts in a direction which is slightly inclined relative to the axis of the valve stem v, the spring force is properly transmitted to the valve stem and canting or binding of the valve stem is avoided.

While a particular embodiment of the invention has been described in detail and illustrated in the drawings, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein without departing from the scope or spirit of the invention as defined in the appended claims.

I claim:

1. A safety valve device comprising a casing having an inlet for a pressure fluid and a valve seat surrounding said inlet, an open-ended guide cylinder fixed in said casing coaxial with said valve seat, a valve member slidable in said guide cylinder with a free working clearance between said valve member and cylinder, said valve member having a valve surface at one end to cooperate with said valve seat and defining an internal back pressure chamber opening at the other end of the valve member, said casing including a fixed cover portion defining the end of said back pressure chamber remote from said one end of the valve member, a valve lift restraining member secured on said fixed cover portion of the casing for limiting the axial movement of said valve member in the direction away from said valve seat, a valve stem extending axially from said back pressure chamber and slidably passing through said restraining member to the exterior of said chamber, valve loading means outside of said chamber and acting on said stem for continuous urging the latter toward the valve seat, means for transmitting the force exerted on said valve stem by the loading means to said valve member, the surface of said valve seat facing toward said valve surface having circular vortex grooves, said lift restraining member limiting the axial movement of said valve member away from said valve seat to a position in which the end portion of said guide cylinder adjacent said valve surface projects axially beyond the latter to define an annular vortex chamber opening upwardly into said clearance between the valve member and guide cylinder so that, when the valve member is lifted off said valve seat and pressure fluid flows radially outward from said inlet between said valve surface and the grooved surface of the valve seat, said vortex grooves and said annular vortex chamber create areas of high pressure to assist in lifting the valve member from the valve seat, said clearance between said valve member and guide cylinder being formed with a radially enlarged portion, an impact sleeve having a shorter axial length than said enlarged portion of the clearance and disposed in the latter for axial movement relative to said valve member, and a radial flange extending outwardly from said other end of the valve member to be contacted by said impact sleeve when the latter is displaced relative to said valve member in the direction toward said other end whereby during lifting of said valve member from said valve seat, pressure fluid enters said clearance from said annular vortex chamber to drive said impact sleeve against said flange for further assisting the lifting of said valve member off said valve seat.

2. A safety valve device according to claim 1; wherein said lift restraining member has lugs extending axially therefrom toward said valve member and engageable with said flange when the valve member is fully lifted from said valve seat to prevent rotation of said valve member and consequent wearing of said means transmtiting the loading means force from said valve stem to said valve member, and means securing said lift restraining member against rotation to said casing.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain