US3572370A - Ball type valve - Google Patents

Abstract

BALL TYPE VALVE PARTICULARLY SUITED FOR USE AS AN ANGLE COCK IN RAILWAY AIR BRAKE SYSTEMS. THE VALVE IS CHARACTERIZED IN THAT THE SPHERICAL HEAD: (A) IS THE DEFORMABLE VALVING ELEMENT SUBJECT TO WEAR AND CAN BE REPLACED EASILY WITHOUT USING SPECIAL TOOLS OR REQUIRING REMOVAL OF THE VALVE FROM THE LINE, (B) IS UNIFORMLY COMPRESSED AROUND THE ZONE OF CONTACT WITH THE SEAT IN THE CLOSED POSITION, (C) MAY BE BALANCED WITH RESPECT TO THE PRESSURES AT BOTH SIDES OF THE SEAT, AND (D) TRANSLATES ALONG ITS OWN CENTERLINE AND PIVOTS ABOUT AN AXIS ECCENTRIC TO THE CENTER OF THE SEAT SO THAT IT ROTATES ON THE SEAT FOR AN INITIAL PHASE OF ITS OPENING MOVEMENT AND SEPARATES FROM THE SEAT DURING THE FINAL PHASE OF SUCH MOVEMENT.

Description

March .23, 1971 .T. H. ENGLE 5 3 am; TYPE VALVE Filed Oct. 16, 1969 2 Sheets-Sheet 1 FIG! INVENTOR THOMAS H. ENGLE BY X ATTORNEYS March 23, 1971 T. H. ENGLE 3,512,310

BALL TYPE VALVE Filed Oct. 16, 1969 ,2 Sheets-Sheet 2 E": I l3 u 12o. l8 l9 4 7 J I I 23 I I4 i 13a FIGS THOMAS H. ENGLE INVENTOR ATTORNEYS United States Patent Oflice 3,5723% Patented Mar. 23, 1971 US. Cl. 137-315 8 Claims ABSTRACT OF THE DISCLOSURE Ball type valve particularly suited for use as an angle cock in railway air brake systems. The valve is characterized in that the spherical head:

(a) is the deformable valving element subject to wear and can be replaced easily without using special tools or requiring removal of the valve from the line;

'(b) is uniformly compressed around the zone of contact with the seat in the closed position;

() may be balanced with respect to the pressures at both sides of the seat; and

(d) translates along its own centerline and pivots about an axis eccentric to the center of the seat so that it rotates on the seat for an initial phase of its opening movement and separates from the seat during the final phase of such movement.

BACKGROUND AND SUMMARY OF THE INVENTION There is a need in the railroad industry for a reliable ball type angle cock of competitive price which can be operated by a relatively small torque, affords good flow metering, and allows easy replacement of the wearing valving element without removing the valve from the brake pipe or requiring special tools. The object of this invention is to provide a ball type valve which satisfies this need.

According to the preferred form of the invention, the deformable, wearing element of the valve is the spherical head which is mounted on a pivoting carrier which can be withdrawn from the valve body along the stem axis after removal of a stem bonnet. The head, which can slide along its centerline relatively to the carrier, is balanced with respect to pressure and is spring biased into engagement with a rigid, nonwearing seat. As the valve opens, the head swings clear of the seat, so the risk of entrapment of foreign particles between the head and seat is minimized. Moreover, the deformable element is compressed uniformly around the circumference of the zone of contact with the seat in the closed position, and this, of course, tends to increase sealing reliability under low temperature condition. The pivot axis of the carrier is eccentric to the center of the seat in two perpendicular directions, and outward translation of the head under the action of the biasing spring is limited. The arrangement is such that the head slides across, or rotates on, the seat, and thus affords good flow graduation, for only an initial portion of its opening movement, and thereafter the head lifts off the seat. This scheme permits use of the spring to develop the head-seat contact pressure without risk of permitting a corner of the seat to gouge the head during its closing movement.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiment of the invention is described herein in detail with reference to the accompanying drawings in which:

FIG. 1 is an axial sectional view of the improved angle cock with the head in closed position and the handle rotated 90 into the plane of section.

FIG. 2 is an enlarged sectional view taken on line 22 of FIG. 1, but showing the head in open position.

FIG. 3 is an exaggerated schematic diagram showing the effect of the valve geometry.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the new angle cock in cludes a cast body 11 containing a through flow passage 12, a rigid, nonwearing annular seat 13 which is pressed into the body and encircles passage 12, and a deformable head 14 which is mounted on a pivoting carrier 15. Seat 13 preferably is made of stainless steel and has either a conical or a spherical valving surface 13a. However, surface 13a may be a convex surface of revolution formed, for example, by rounding the left end of seat 13. Head 14 is made of either rubber or glass-filled Teflon and is provided with a valving surface 14a in the form of a zone of a sphere which has a centerline that lies in a common plane with the centerline of surface 13a. If surface 13a is spherical, the radii of the two valving surfaces are equal. On the other hand, if surface 13a is conical or convex, the radius of surface 14a is selected so that this surface is tangent to surface 13a at its medial diameter.

Head 14 is formed with a cylindrical bore 16 which is coaxial wih surface 14a and which receives a piston 17 fixed to carrier 15. Piston l7 and cylinder 16 guide head 14 for translatory motion along the centerline of surface 14a. The head is biased in the outward direction along this centerline by a pair of coil compression springs 18 and 19, and its motion in this direction is limited by a stop screw 21 which is threaded into piston 17 and is coaxial with surface 14a. Piston 17 and cylinder 16 also define a motor space 22 within head 14 which is sealed from the portion 12a of passage 12 to the left of seat 13 by an O-ring 23, but is connected with the opposite portion 12b of the flow passage through the annular clearance space 24 between the head and stop screw 21. The diameter of piston 17 is equal to the medial diameter of valving surface 13a, and therefore it should be evident that head 14 is substantially balanced with respect to the pressures in passage portions 12a and 12b. As a result, head-seat contact pressure depends only upon the force developed by springs 18 and 19 and can be relatively low. This, of course means that only a small torque will be required to open and close the valve.

The head carrier 15 is formed at one end into a stem 15a which projects from body 11 and to which is afiixed a conventional angle cock handle assembly 25. Carrier 15 also is provided with a pair of trunnions 15b and 150 which journal it in bonnet 26 and body 11, respectively, for rotation about a pivot axis 27 which is normal to the common plane containing the centerlines of valving surfaces 13a and 14a. Stops (not illustrated) define the open and closed positions of the valve. so carrier 15 has a range of motion of The bonnet 26 is held in body 11 by a snap ring 28 which bears against an annular shoulder 29 formed on its outer periphery and is seated in a groove formed in body 11. Shoulder 29 is spaced inward from the end face 26a of bonnet 26 a distance greater than one-half the diameter of the wire from which ring 28 is made, and the outer periphery of the bonnet between the shoulder and end face 26a is shaped to prevent snap ring 28 from moving out of the body groove. This arrangement insures that bonnet 26 will not be ejected from body 11 by the pressure in passage portion 12a which acts upon its inner end face 26b. Bonnet 26 is urged upward, as viewed in FIG. 1, against snap ring 28 by a coil compression spring 31, so the bonnet can be moved downward to uncover, and thereby permit installation or removal of, snap ring 28. The body bore which re- 3 ceives bonnet 26 is large enough to accommodate the assembly comprising carrier 15 and valve head 14; therefore, replacement of the valve head can be accomplished easily without removing the valve body from the line or using special tools.

The lower end of biasing spring 31 is seated on a snap ring fitted in a groove in carrier 15, and thus serves the additional purpose of urging the carrier into abutment with the body shoulder 32. Therefore, if the valve is so manufactured that the vertical distance between shoulder 32 and the centerline of seat 13 is matched closely to the corresponding distance between the lower end of carrier 15 and the centerline of head 14, spring 31 will insure that the two centerlines remain in the same plane during service. The lower end of carrier 15 is in continuous communication with the atmosphere through a filtered vent port :33, and the diameters of the trunnions 15b and 150 are equal. Therefore, carrier 15 is balanced with respect to pressure in the direction of the pivot axis 27, and, as a result, spring 31 need exert only a moderate biasing force.

As those skilled in the art are well aware, the emergency portion of an automatic air brake system responds to a prescribed rate of decrease of brake pipe pressure. Therefore, when the angle cock at the end of a train is opened to charge the brake pipe sections of newly added cars, an unintended emergency brake application can be produced throughout the train if the valve does not afford reasonably good flow metering. In the case of a conventional ball type valve, this flow-graduating action normally is provided by causing the head to pivot about an axis that passes through the center of the seat so that the head will slide across the seat. However, this approach cannot be used in the new valve because here headseat contact pressure is developed by a spring, and consequently the head must be able to translate along its centerline, and the head must be spaced from the seat in the fully open position of the valve in order to minimize restriction to flow through passage 12 and to preclude entrapment of foreign particles between the mating valving surfaces 13a and 14a. If head 14 pivoted about an axis which passes through the center of surface 13a, biasing springs 18 and 19 would shift it outward along piston 17 as soon as the head was moved beyond the margin of the seat. As a result, the corner 13b of the seat would gouge the edge region 14b of the head 14 each time the valve was closed. In accordance with the teachings of the invention, this problem is eliminated, without impairing the ability of the valve to afford good fiow-metering action, by the combination of stop 21 and a proper location for pivot axis 27.

Referring to the schematic diagram of FIG. 3, the pivot axis 27 of carrier 15 is offset longitudinally from the center SC of valving surface 13a in the direction of seat 13, and also is offset laterally from center SC in the direction away from head 14 when the latter is in the fully open position H-l. (It should be understood that the center SC of a non-spherical surface 13a is the center of an imaginary sphere which is tangent to the surface and has a radius equal to the radius of head surface 14a.) In a typical case, the longitudinal and lateral eccentricities X and Y are about 0.043 and 0.096 inch, respectively. Preferably, the centerlines SCL and HCL of the two valving surfaces 13a and 14a, respectively, coincide when the valve is fully closed, and therefore axis 27 is spaced from the head centerline HCL a distance equal to the lateral eccentricity Y.

When the head 14 is moved from the fully open position H-l toward the closed position H-4, its centerline HCL remains tangent to an imaginary circle 34 centered at axis 27 and having a radius equal to the lateral eccentricity Y, and initially its center HC moves in a circular are 35 which also is centered on axis 27 and has a radius determined by stop 21. In the illustrated example, it is assumed that stop 21 is so set that are 35 intersects seat centerline SCL at the center SC of the seat, but settings giving arcs of slightly greater or smaller radii can be used. As the head swings to the H-2 position, its valving surface 14a is gradually brought into abutment with seat surface 13a. Since, in the H-2 position, the center HC2 of head surface 14a coincides with the center SC of the seat surfaces 13a, the two surfaces now will be perfectly aligned and will be in contact with each other throughout a zone of contact of considerable angular extent. The location of the H-2 position depends upon the ratio of the lateral eccentricity Y to the longitudinal eccentricity X and usually lies between about 50 and 60 away [from the open position H-l. In any case, since the leading edge 14b of the head is well within the margin of the seat by the time the head reaches this position of initial contact H-2, it will be evident that the edge cannot be gouged by seat corner 13b.

As head 14 moves from the H-2 position to the fully closed H-4 position, seat 13 forces it to move inward against the opposing bias of springs 18 and 19, so the center of surface 14a ceases to move along circular are 35. During this phase of the closing movement, the centerline HCL of head surface 14a first moves away from seat center SC and then, as the head approaches the H4 position, it moves into coincidence with seat centerline SCL and again passes through the seat center. The position H-3 of maximum misalignment is midway be tween the two positions H-2 and H4 wherein the seat and head centers coincide. If the parts of the valve were perfectly rigid, and head 14 could not cock even slightly on guide piston 17, the head could lift off seat 13 as shown by the dashed line position H-3 in FIG. 3 and open a narrow gap of considerable angular extent between the mating surfaces 13a and 14a. In practice, however, the head 14 is deformable, and it can cock on its guide. Therefore, since the maximum spacing or misalignment 2 between head centerline HCL-3 and seat center SC is on the order of only 0.005 to 0.010 inch, the surfaces 13a and 14a will remain in contact. In effect, the translatory and rotary motions of head 14 cause it to rotate about the seat center SC. Thus, surface 14a merely slides across or rotates on seat surface 13a as the head moves between the H-2 and H4 positions.

During opening movement of the valve, head surface 14a tends initially to rotate about the center SC of seat surface 13a, so it slides across the seat surface and gradually opens the flow path through passage 12. The combined effects of this area-graduating action and the low torque level afforded by the use of a pressure balanced head allows the operator to meter flow through the valve well enough to control the rate at which the pressures in passage portions 12a and 12b equalize. As a result, inadvertent emergency brake applications can be avoided. When the head reaches the H-2 position, the flow area of the valve will have increased to the limit of the range in which useful flow metering can be accomplished. Therefore, at or about this position, head 14 engages stop 21. The stop precludes further outward translation of the head along its centerline, so, as carrier 15 continues to pivot toward fully open position, head 14 commences to rotate about axis 27. As a result, valving surface 14a is lifted away from seating surface 13a.

Since the valving surfaces 13a and 14a are permitted to slide across each other through only the limited range of motion required for effective flow metering, the new design minimizes the risk that foreign particles caught between the valving surfaces will score one or the other in a manner that produces a leakage path across the seating surface 13a when the valve is closed. It also will be observed that, when head 14 is in closed position H-4, it is compressed uniformly around the entire 360 of the head-seat contact zone (i.e., all radii from center SC to surface 13:: pass through equal thicknesses of head material). This arrangement tends to increase the reliability of the seal between the head and seat, particuularly under low temperature operating conditions.

Although the flow metering action afforded by the new valve satisfies the requirements for angle cocks used in railway brake systems, it should be evident that the valve will afford more precise metering action if head edge 14b is provided with a small V-notch or metering slot analogous to those employed in hydraulic valves of the sliding spool type.

It should also be noted that, while the head 14 in the preferred valve is balanced with respect to the pressures in passage portions 12a and 12b, the basic design can be modified to afford a controlled amount of unbalance in situations where the direction of flow does not change. For example, if the fluid always flows from left to right in FIG. 1, the head-seat contact force can be made to vary with the pressure in passage portion 12a by merely reducing the diameter of piston 17 relatively to the medial diameter of seat surface 13a.

I claim:

1. A ball type valve comprising (a) a body (11) containing a flow passage (12) encircled by a seat (13) having an annular valving surface (13a);

(b) a carrier (15) mounted in the body for rotation about a pivot axis (27) which lies in a plane which is normal to the centerline (SCL) of the valving surface (13a) of the seat and is positioned between that surface and its center (SC);

(c) a deformable head (14) which is mounted to rotate with the carrier and has a valving surface (14a) in the form of a zone of a sphere,

(d) the centerlines (HCL and SCL) of the two valving surfaces lying in a common plane and being spaced equal distances (Y) from the pivot axis (27);

(e) means (16, 17) guiding the head (14) for sliding movement relatively to the carrier along the centerline (HCL) of its valving surface (14a);

(f) spring means (18, 19) biasing the head outward along said guiding means; and

(g) stop means (21) limiting outward movement of the head under the action of said biasing means,

(h) whereby the opening movement of the head (14) consists of an initial phase in which it rotates essentially about the center (SC) of the seat and its valving surface (14a) slides across the valving surface (13a) of the seat, and a final phase in which it rotates about the pivot axis (27) and its valving surface separates from the seat.

2. A valve as defined in claim 1 in which the guide means comprises cooperating piston and cylinder elements (17, 16) which are coaxial with said valving surfaces (13a, 14a), one of said elements being fixed to the carrier (15 and the other being fixed to the head (14).

3. A valve as defined in claim 2 in which the head (14) is balanced with respect to the pressures in portions (12a, 12b) of said flow passage (12) at opposite sides of the seat when the valve is closed.

4. A valve as defined in claim 3 in which (a) said piston (17) and cylinder (16) define a closed space (22) within the head which communicates with said flow passage at one side (12b) of the seat; and

(b) the diameter of said cylinder is equal to the median diameter of the valving surface (13a) of the seat. 5. A valve as defined in claim 1 in which, in the closed position of the valve, the centerlines (HCL, SCL) and centers (HC, SC) of the two valving surfaces (13a, 14a) coincide.

6. A valve as defined in claim 1 wherein (a) the carrier (15) is provided with a stern (15a) which projects from the body (11) and with a pair of trunnions (150, 1512) which journal it for rotation in the body and in a removable bonnet (26) which closes an opening in the body; and (b) said opening in the body is large enough to pass the assembly including the carrier (15) and the head (14).

7. A valve as defined in claim *6 wherein (a) the carrier (15) is balanced with respect to the pressure in the body in the direction of said pivot axis (27); Y

(b) the bonnet (26) is free to slide in said body opening and is held in place by a snap ring (28) which is seated in the body and is adapted to bear against a portion (29) on the outer periphery of the bonnet; and

(c) a spring (31) reacting between the bonnet (26) and the carrier (15) urges the bonnet outward against the snap ring (28) and urges the carrier inward into end abutment with a wall (32) in the body.

8. A valve as defined in claim 7 wherein the snap ring (28) is confined by the bonnet (26) and the body (511) when said bonnet portion (29) is in abutment with it, but is exposed sufiiciently to permit removal when the bonnet is forced inward against the opposition of said spring (31).

References Cited UNITED STATES PATENTS 3,033,513 5/1962 Vulliez 251--163 3,254,872 6/1966 Roos 251-163 3,301,271 1/1967 Burke 137-315 HAROLD W. WEAKLEY, Primary Examiner US. Cl. X.R. 251163, 283

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