GB2129526A - Valve - Google Patents

Abstract

An axially-movable abrasion- resistant valve member 36 is resiliently urged by a guide 74 toward its centered position with respect to the valve seat 20, this also serving to dampen vibrations in the valve member. The guide 74 may be of metal and may be annular or comprise fingers. <IMAGE>

Description

SPECIFICATION Valve The present invention relates to a valve having an improved valve plug guide. Prior to the present invention, valves having movable plugs to coact with a valve seat have had fixed support placed above the valve seat. Such supports have been unsatisfactory because of particle build-up on the guide which prevents proper functioning thereof, because of vibrations in the body and the guide which can damage the plug, and because the support is usually a different material than the plug so that temperature changes can cause the support to either interfere with the plug or not to provide adequate support therefor.It is important that the plug receive proper guiding under all conditions to which the valve is exposed so that the plug is maintained in centered relationship to the seat to maintain desired flow control and in valves in which brittle abrasion-resistant materials are used for the plug and the seat to avoid damage to the plug and seat caused by an off-center engagement therebetween.

The C.C. Anthers et al Patent No. 3,338,549 discloses an anti-backlash throttle valve including a plastic (nylon) bushing 22 with split fingers 36 having internal threads of the valve stem 12.

The R.F. Huddleston Patent No. 2,360,606 discloses a valve guide 14 for an internal combustion engine valve 10 which guide surrounds the valve stem 13 and has its fingers 26 engaging scraper ring 15.

A continuously effective stem guide is of particular importance in valves subject to high velocity, abrasive slurry flow. In such valves the valve seat and the exterior portion ofthe plug are preferably made of an abrasion-resistant material which is generally subject to fracture and chipping when subjected to tension loads, small particle impact damage, offcenter seating, vibration and changing thermal conditions.

The present invention relates to an improved valve suitable for high temperature and high velocity flow of fluo-solids. The improved valve includes a body having a inlet, an outlet, an abrasion-resistant valve seat surrounding the passage from said inlet to said outlet, a valve plug having an abrasion-resistant outer sleeve and a valve guide supported from said body and extending in surrounding relationship to said valve plug, said valve guide resiliently engaging said valve plug sleeve to maintain it in centered position with respect to said valve seat.

An object of the present invention is to provide an improved plug valve for high velocity, high temperature fluo-solid flow in which the plug is resiliently urged toward its centered position with respect to the valve seat.

Another object is to provide an improved valve having an improved valve plug guide which dampens vibrations in the plug.

A further object is to provide an improved valve plug guide in a valve which is not subject to problems of particle accumulation, or damage due to differential temperature expansion of the plug and guide.

These and other objects and advantages of the present invention are hereafter set forth and explained with respect to the drawings wherein: Figure 1 is an external view of the improved valve of the present invention showing the central portion of the valve in section to illustrate the valve seat, valve member and the valve guide and their relative positions.

Figure 2 is a partial detailed sectional view of the improved valve of the present invention.

Figure 3 is a view of the valve plug and guide taken along line 3-3 in Figure 2.

Figure 4 is a partial, detailed sectional view of a modified form of the improved apparatus of the present invention.

Figure 5 is a view of the valve plug and guide taken along 5-5 in Figure 4.

Valve 10, shown in Figures 1,2 and 3, includes valve body 12 which has inlet 14 extending to internal valve chamber 16 and outlet 18 extending from valve chamber 16 through valve seat 20.

Bonnet 22 is secured to body 12 by studs 24 and nuts 26 and includes annular hub 28 which is externally threaded and extends inwardly into chamber 16.

Valve stem 30 extends through hub 28 and is connected to actuator 32. Suitable sealing means 34 is provided surrounding valve stem 30 within the hub 28 to provide a seal therebetween. Plug 36 is connected onto the end of valve stem 30 as hereinafter explained and is moved with the valve stem 30 toward and away from the valve seat 20. Plug 36 is made of suitable abrasion-resistant material as is insert 38 in valve seat 20.

Valve seat insert 38 is held in engagement between rings 40 and 42 which are interconnected by the cap screws 44. Insert 38 includes an exterior flange 46 which is clamped between the rings and spring seal 48 is positioned around the exterior of flange 46 as shown. It is also preferred that the outlet 18 be lined with sleeve 50 of suitable abrasionresistant material As best seen in Figure 2, plug 36 is connected to valve stem 30 by sleeve 52 which is threaded onto the exterior of valve stem 30 and extends around plug 36 beyond shoulder 54 thereon to retain plug in engagement with the end of stem 30. Pin 56 extends through the end of sleeve 52 and through the stem 30. Plug 36 includes annular recess 58 in which spring 60 is positioned to maintain plug 36 centered within sleeve 52. Axial position between stem 30 and plug 36 is maintained by spring 75.Tubular support 62 is threaded onto the exterior of hub 28 as shown and extends into the valve chamber 16 in surrounding relationship to the plug 36 and stem 30. Support 62 extends into close spaced relationship with the valve seat 20 and includes an inwardly extending flange 64 at its innermost end. Tube 66 is positioned in abutting relationship to the end of hub 28, surrounds sleeve 52 and abuts ring 68. Guide tube 70 is positioned in surrounding relationship to the outer end of sleeve 52 and abuts the flange 64 as shown.

Further guide tube 70 at its inner end abuts the seal assembly 72 which is in abutment with ring 68. Seal assembly 72 includes seal rings 72a and 72b with ring 72c therebetween. The outer end of guide tube 70 has fingers 74 projecting therefrom as best shown in Figures 2 and 3 which fingers 74 extend inwardly and have resiliency as hereinafter defined. The free diameter of fingers 74 is less than the maximum outer diameter of the plug 36 and in the retracted position of plug 36 shown in Figure 2, engage on the exterior tapered end of plug 36. As plug 36 is moved toward seat 20, fingers 74, which function as a plug centering guide, are sufficiently flexible to move outwardly allowing plug 36 to pass freely therethrough but have sufficient resiliency to create a force against the plug 36 assuring that it will be centered and providing a dampening of vibrations therein.

The preferred centering guide of the present invention is intended to be a constant stress beam which provides a force to return the plug to the center position. The stiffness of these beams provide a damping force to reduce plug vibration. The deflection of these beams is sufficient so that contact is maintained at elevated temperatures despite differences in coefficients of thermal expansion between the plug and the guide. The guide surrounds the plug and generally is of metal so that it will have greater expansion and will not contract onto the plug causing a problem.

In the modified form of the invention illustrated in Figures 4 and 5, the main portions of the invention are the same and the changes made in the centering guide tube 70'. In Figures 4 and 5, the similar parts have identical numbers since they are identical in structure with those shown and described in Figures 1,2 and 3. Centering guide 70' does not include the fingers 74 which are included on guide tube 70 but rather has an annular extension 76 which terminates in close spaced relationship or engaging relationship with the outer tapered portion of the outer end of plug 36 when plug 36 is retracted. Thus, when plug 36 is moved inwardly towards valve seat insert 38, the annular extension 76 is held in supporting resilient engagement with plug 36 to assure that it is properly centered and to function as a constant stress beam.

As can be seen from the description of the two forms of the present invention, the improved guide of the present invention functions as an annular spring arranged around the portion of the plug closest to the valve seat in a manner to provide a force tending to return the plug to its centered position. This structure has been found to avoid the problems of vibrations, and of off-center engagement of the plug with the valve seat insert and is not affected negatively by being subject to substantial changes in temperature or extremes of elevated temperature.

Claims (12)

1. A valve having a body having a chamber, an inlet into the chamber and an outlet from the chamber, a seat surrounding said outlet, a valve member, a stem extending through said body into said chamber, an actuator connected to move said stem axially, means connecting said valve member to said stem whereby movement of said stem moves said valve member toward and away from said seat, and characterized by a guide resiliently urging said valve member toward its centered position with respect to said valve seat.

2. A valve according to Claim 1 wherein said valve member is made from an abrasion-resistant material.

3. A valve according to Claim 1 or 2 wherein said guide surrounds said valve member and is supported from said body.

4. A valve according to Claim 1,2 or 3 including means for supporting said guide in surrounding relation to said valve member.

5. A valve according to any of the preceding claims wherein said guide functions as a constant stress beam in its urging of said valve member.

6. A valve according to Claim 1 wherein the engagement of said valve member by said guide is sufficient to dampen vibrations of said valve member.

7. A valve according to any of the preceding claims wherein said guide has an inward projection in close spaced relationship to said seat, the inner portion of said projection engaging the exterior of said valve member.

8. A valve according to Claim 7 wherein said inward projection of said guide is an inwardly directed flange.

9. A valve according to Claim 7 wherein said inward projection of said guide is a plurality of fingers.

10. Valve according Claim 6 wherein said inward projection as a free diameter less than the diameter of the untapered portion of said valve member.

11. A valve according to any of the preceding claims wherein an abrasion-resistant said valve member is made of a abrasion-resistant material.

12. A valve substantially as hereinbefore described with reference to and as shown in the accompanying drawings.