AU8948998A - A valve - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): JOHN VALVES PTY LTD Invention Title: A VALVE The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 A VALVE This invention relates to a valve and, in particular, to a gate valve.

Gate valves having an inside screw stem configuration include a valve body which has a bonnet for receiving the stem and a valve element to be closed by the stem. A seal housing is arranged on the bonnet to seal the stem to prevent fluid which flows through the valve from seeping out of the valve past the valve stem. Thrust developed when the stem is rotated to open or close the valve is taken by the stem housing. This generally requires the stem housing to be made from metal material and usually the same material from which the valve body is made or other material of comparable strength with superior corrosion resistant properties.

The present invention may be said to reside in a valve including: a valve body having a bore for allowing flow of fluid through the valve; a valve element movable between open and closed positions for selectively opening and closing the bore to, respectively, open and close the valve; a rotatable stem coupled to the valve element for driving the valve element between the open and closed positions; a first thrust collar on the stem and arranged in the valve for taking thrust exerted by the valve stem when the valve stem is rotated to either close or open the valve; a seal housing for sealing the valve stem; and a second thrust collar on the stem and abutting the valve body for taking thrust exerted by the valve stem when the valve stem is rotated to either open or close the valve.

H: \Karen\Keep\JOHN-VALVES-a-valvedoc 23/10,98 3 The second thrust collar takes the thrust exerted by the stem rather than the seal housing so the seal housing can be formed from another material of reduced structural strength such as plastic. Furthermore, the ability to form the seal housing from plastic material enables the seal housing to be used on other valves where structural rigidity is not required, thereby providing a modular seal housing which can be used with inside screw gate valve configurations in which the second thrust collar is used to take thrust or in other configurations such as outside screw valve configurations where thrust is contained in the yoke sleeve or drive nut. In such configurations, thrust collars are not required.

Preferably the seal housing includes a bore for receiving the stem and a recess for accommodating the second thrust collar. Obviously in inside screw arrangements, the recess receives the thrust collar. In outside screw arrangements where thrust collars are not required, the recess can be used to accommodate a seal for sealing the valve stem.

The thrust collars may be split thrust collars applied to the stem or may be permanently fixed to the stem by being made integral with the stem or otherwise attached to the stem.

In the most preferred arrangement, the second thrust collar received in the recess of the seal housing is a split thrust collar and the first thrust collar is integrally formed on the valve stem.

The invention may also be said to reside in a seal housing for a valve, including: a flange section having a plurality of openings for receiving fasteners to secure the seal housing to a valve body; H: \Karen\leep\JOHN-VALVES-a-valve.doc 23/10/98 4 a bore for receiving a valve stem; and a recess in alignment with the bore for receiving a thrust collar coupled to the valve stem so that the thrust collar can abut the valve body when the seal housing is attached to the valve body.

Preferably the seal housing includes grooves for receiving seal elements for sealing against the valve stem.

Preferred embodiments of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view of a valve along the line A-A of Figure 2; Figure 2 is a cross-sectional view along the line B-B of Figure 1; and Figure 3 is a view of an outside screw valve configuration.

Figures 1 and 2 show a gate valve of the inside valve stem configuration. The valve has a valve body 10 which includes a lower section 12 defining a bore 14. A bonnet 16 is coupled to the lower section 12 to complete the valve body 10. A valve element 18 is arranged within the body and is in screw thread engagement with a valve stem 20 in a manner well known. The bonnet 16 has an upper flange 22 for receiving a seal housing 24. The seal housing 24 has a flange 26 which sits on the flange 22. The flanges 22 and 26 have openings 28 for receiving bolts 30. Nuts 32 screw onto the bolts 28 to secure the seal housing 24 onto the bonnet 16.

A first thrust collar 40 is provided on the stem 20 and is most preferably formed integral with the stem 20. The thrust collar 40 sits into a cutout or recess 42 in the bonnet 16.

H: \Karen\Keep\JOHN-VALVES-a-valve doc 23/10/98 5 The seal housing 24 includes a central bore 50 through which the stem 20 passes. The bore 50 has a recess portion 52 arranged coaxially with the bore 50 for accommodating a second thrust collar 60. The second thrust collar 60 may be integral with the valve stem 20 or may be a split thrust collar formed in two parts which are separate from the stem and applied to the stem 20. The bonnet 16 has a bore 29 which receives the stem 20. As is apparent from Figures 1 and 2, the thrust collar 60 is of larger diameter than the bore 29 and the thrust collar 60 abuts upper surface 22a of the flange 22. The seal housing 24 includes grooves 72 for receiving sealing rings which seal against the valve stem and a circular groove 74 in flange 26 for sealing against upper surface 22a of the bonnet 16.

A hand wheel 70 is connected to the stem 20 for moving the valve element 18 between the open position shown in Figures 1 and 2 and a closed position in which it blocks the bore 14 to prevent flow of fluid through the valve. By rotating the hand wheel 70 in a clockwise direction, the valve stem is rotated so that the screw thread engagement between the valve stem 20 and the valve element 18 causes the valve element 18 to be driven downwardly in the direction of arrow A in Figures 1 and 2. Thrust applied to the valve stem 20 during movement of the stem 18 downwardly in the direction of arrow A is taken by the thrust collar 40 and transferred to the bonnet 16 in the vicinity of the groove or recess 42. When the valve is to be opened, the handle is rotated in the opposite direction so that the screw thread engagement between the stem 20 and the valve element 18 causes the valve element 18 to move in the direction of arrow B to open the valve. During this movement, thrust applied to the stem 20 is taken by the thrust collar 60 and transmitted to the bonnet 16 where the thrust collar abuts the upper surface 22a of the bonnet 16.

Thus, the double thrust collar arrangement shown in Figures H: \Karen\Keep\JOHN-VALVES-a-valve.doc 23/10/98 6 1 and 2 takes the thrust applied to the stem 20 during opening and closing of the valve and transmits that thrust to the bonnet 16. The thrust is not taken by the seal housing 24 which means that the seal housing 24 can be made from reduced strength material such as plastic and a modular seal housing 24 can be made to be used with the valve of Figures 1 and 2 and also other valves such as that shown in Figure 3.

Figure 3 shows an outside screw valve configuration which is of known design except that it incorporates the seal housing 24 described with reference to Figures 1 and 2.

The valve of Figure 3 has a stem 20 which opens and closes a valve element 18 to in turn open and close bore 24.- In Figure 3, the left hand side of the drawing shows the valve element 18 in the open position and the right hand side designated by reference numeral 18' shows the valve element closing the bore 24. The stem 20 has handle which is rotated to raise and lower the stem 20 and therefore the valve element 18 by vertical movement of the stem 20. The stem 20 is engaged with a yoke sleeve or drive nut 80 so that when the handle 70 is rotated, the yoke sleeve or drive nut 80 also rotates to draw the stem upwardly to open the valve downwardly to close the valve.

In this embodiment, the recess 52 in the seal housing 24 accommodates a seal 90 instead of a thrust collar because the thrust of the stem 20 is taken by yoke sleeve or drive nut 80 and therefore additional thrust collars are not required in the arrangement shown in Figure 3.

The fact that the same seal housing 24 can be used in the valves of Figures 1 and 2 and also Figure 3 means a single part can be used in two different valves thereby reducing the amount of componentry required to form the inside stem arrangement of Figures 1 and 2 or the outside stem H: \Xaren\Keep\JOHN-VALVES-a-vale doc 23/10/98 7 arrangement of Figure 3.

As will be clear from the previous description, if the arrangement of Figures 1 and 2 is used, the recess 52 in the seal housing 24 accommodates the second thrust collar applied to the stem 20 whereas in the arrangement of Figure 3, the recess 52 can accommodate an additional seal to further assist in sealing of the stem 20 within the valve.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiments described by way of example hereinabove.

H: \Karen\Keep\JOHN-VALVES-.-valve.doc 23/10/98

Claims (4)

1. 2. The valve of claim i, wherein the seal housing includes a bore for receiving the stem and a recess for accommodating the second thrust collar.
2. 3. The valve of claim i, wherein the thrust collars are split thrust collars applied to the stem or permanently fixed to the stem by being made integral with the stem or otherwise attached to the stem.
3. 4. The valve of claim 1, wherein the second thrust collar received in the recess of the seal housing is a split thrust collar and the first thrust collar is integrally formed on the valve stem. A seal housing for a valve, including: a flange section having a plurality of openings H: \Karen\Keep\JOHN-VALVEs-a-valvedoc 23/10/98 9 for receiving fasteners to secure the seal housing to a valve body; a bore for receiving a valve stem; and a recess in alignment with the bore for receiving a thrust collar coupled to the valve stem so that the thrust collar can abut the valve body when the seal housing is attached to the valve body.
4. 6. The housing of claim 1, wherein the seal housing includes grooves for receiving seal elements for sealing against the valve stem. Dated this 23rd day of October 1998 JOHN VALVES PTY LTD By their Patent Attorneys: GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia. H: \Karen\Keep\JOHN-VALVES-a-valve.doc 23/10/98