Valves and valve actuation – Rotary valves – Seat or interface seal
Reexamination Certificate
2000-04-20
2001-10-02
Lee, Kevin (Department: 3754)
Valves and valve actuation
Rotary valves
Seat or interface seal
C251S315010, C251S315100, C251S286000
Reexamination Certificate
active
06296229
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a metal improved ball valve, specifically designed for gas application.
The invention relates moreover to an improved pressing method for pressing the metal valve body, e.g. a hot-pressing method for a brass valve body.
BACKGROUND OF THE INVENTION
While the improved valves according to the present invention have been specifically designed for gas systems, in which they must meet preset stringent requirements, such as a high resistance against outer high temperatures, i.e. in fire conditions, they can also be used for any liquid fluids.
The inventor believes that of the above prior valves, the valve disclosed in the Italian Utility Model No. 209,019, corresponding to the U.S. Pat. No. 4,714,236, represents the most pertinent status of the art.
While ball valves for liquids can be made from metals or plastic materials, ball valves for gases can be exclusively made from metal materials, since a plastic material cannot resist against, for example, the high outer temperatures of a fire event.
Even if the ball shutter and screw elements of plastic material ball valves are conventionally made as a plastic material single piece, to which the control member, such as a knob, can be fixedly coupled, it should be apparent that the above mentioned single-piece ball shutter-rod unit, as well as the valve body, and the related molding and assembling processes, cannot be merely adopted when using a metal, such as brass instead of a plastic material.
Thus, in the following disclosure exclusively metal valves will be considered.
Since the gas valves must meet technical requirements set by very stringent regulations, it would be moreover apparent that these valves must operate in a very reliable manner. On the other hand, it has been found that prior valves could be further improved both operatively and construction-wise.
With reference to
FIG. 1
, showing the prior art disclosed in the U.S. Pat. No. 4,714,236, a valve
1
comprises a valve body
2
, arranged between an inlet fitting
3
and an outlet fitting
4
, and a chamber
6
for engaging therein a ball shutter
7
, supported between two opposite sealing gaskets
8
, which are individually housed in a respective annular recess
9
.
As the bottom portion of the valve
6
, having a circular shape in a middle horizontal plane thereof, has a substantially spherical configuration, the gaskets
8
, on their side facing the chamber
6
inside, circumferentially project cantilever-wise, in a different degree, from their seats. Thus, the compression on the gaskets by the conveyed fluid, i.e. that fluid which is present in the valve, would not be evenly distributed in the circumferential direction and, in a high pressure condition, said gaskets would be deformed with a consequent resistance against a rotary movement of the ball.
Moreover, for lightening the ball shutter, and reduce the shutter material cost, the inside of the shutter
7
is hollowed by turning operations. Thus, this weight reducing process would require a comparatively long operation time and, while allowing to recover the high value metal, would increase the making cost.
With reference again to
FIG. 1
, the valve control rod or screw is indicated by
11
and is engaged in a seat
13
of the collar
12
of the valve body
2
, the screw being clamped by a friction ring or washer
14
and a resilient ring
16
, engaged in a contoured slot
17
of the collar
12
. The reference numbers
18
and
19
respectively indicating a sealing O-ring and a supporting and flame-breaking gasket, housed in corresponding grooves of the rod
11
.
Prior valves are moreover affected by the following drawbacks:
the provision of a comparatively large number of components, such a eleven components for the valve of the U.S. Pat. No. 4,714,236;
the provision of a ball shutter and rod which are removably coupled to one another, thereby requiring two machine tools for making them from a bar material with a consequent increase of the making and assembling cost;
the reduction of the ball weight can be obtained only by a complex and long inner spherical turning of the shutter;
the abutments for limiting the 90° rotary movement of the shutter are formed as lugs on the valve body and co-operate with counter-abutments provided on the control member, for example a knob, thereby if said knobs is loosen or illicitly removed, then the shutter could not be arranged off or on position;
the contoured seat provided in the rod element housing collar increases the machining time and, consequently, the making cost;
the rod coupling means require two discrete components, i.e. a suitably sized locating washer and a clamping resilient ring element.
SUMMARY OF THE INVENTION
Accordingly, the main object of the present invention is to provide an improved metal ball valve, in particular for gas applications, including shutter sealing gaskets which can be evenly circumferentially stressed, and a shutter which can be greatly lightened by a simple and short time machining, and including a small number of components.
Another object of the present invention is to overcome further drawbacks of the prior art, to allow an overall reduction of the making time and cost, while preventing the shutter from being illicitly removed, upon removing the clamping knob.
According to one aspect of the present invention, the above mentioned objects are achieved by an improved gas ball valve.
The invention advantageously provides a single-piece metal screw-shutter assembly, for example of a brass material, which can be made by a single machine tool and in a comparatively short processing time, starting from a bar material or a pressing or die-casting half-finished material.
The invention allows to substantially reduce the weight of the ball shutter, the axial drilling operations being advantageously extended up to the rod portion.
The invention allows to arrange the 90° rotary movement limiting abutments for the shutter in a region between the rod portion and shutter portion, on one side and, on the other side, in the valve body, thereby the rod-shutter assembly can be quickly and accurately driven to a shut-off or open position, or to any middle positions, even if the knob is removed or illicitly detach.
The invention allows to simplify the machining of the seat or recess of the collar housing therein the rod portion, said seat being made as a cylindrical seat.
The invention allows to omit two components for clamping the rod-shutter assembly in the valve body, whereby it is advantageously possible to fixedly clamp the rod-shutter assembly even after having removed the knob or the like.
The hot-pressing process for pressing the valve body provides shutter sealing gasket housing seats in which the gaskets are substantially integrally engaged, or with a small even circumferential projection of said gaskets projecting toward the shutter, without requiring additional machining operations or a long machining time.
The improved metal ball valve, in particular for gas applications, according to the invention, provides a lot of important advantages.
At first, it is possible to smoothly and evenly turn the shutter even under a high pressure condition, since the shutter is evenly supported and clamped on its sealing gaskets through the overall circumferential extensions of said gaskets. The lightening of the shutter, or of the single-piece rod-shutter assembly is comparatively high, and is moreover obtained in a short time and by a single machining operation on a single automatic machine tool.
The provision of the rod and shutter as a single piece, which can be machined from a bar material, contributes to reduce the component number and the machining and assembling time with a consequent reduction of the overall making cost. In particular, this cost would be further reduced since two components (locating anti-friction washer and resilient ring) are omitted, and since the contoured seat for housing said components in the valve body collar is also omitted.
Moreover, the provision of a cylindrical seat in the v
Giacomini S.p.A.
Kirschstein et al.
Lee Kevin
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