IL155603A - Valve and sealing assembly therefor - Google Patents

Description

Valve and sealing assembly therefore, Dorot Valve Manufacturers nwbpm fi'V ii >m C. 143135 VALVE AND SEALING ASSEMBLY THEREFORE FIELD OF THE INVENTION The present invention generally relates to the field of hydraulic control valves, in particular, to a valve assembly for a three-way valve, wherein a sealing block is axially displaceable within the valve assembly.

BACKGROUND OF THE INVENTION Three-way valves are well know in the industry and are generally used to provide fluid connection between an inlet and an outlet pipe where there is a drain or other intermediary pipe. Such valves fall into several categories e.g. rotary-plug valves, ball-valves and valves fitted with an axially displaceable sealing assembly. The present invention is concerned with the latter type, which necessarily have a sealing ring or block that moves between two sealing positions.

Three-way valves of the above referred to type are disclosed, for example in One of the problems with such valves is that, since the sealing element must move between two sealing positions, when the sealing element moves, it must inherently rub or bear against some portion of the valve seat and/or housing. After a number of uses, this will cause some portion of the sealing ring to erode due to rubbing during movement. At some point the sealing ring will no longer provide a complete seal due to the fact that some of its surface material will have eroded and been rubbed off.

Still another drawback associated with prior art three-way valves is concerned with assembly and disassembly of the valve, e.g. for servicing the valve, where in many cases a major casing portion of the valve has to be removed to facilitate removal of the sealing assembly.

Therefore, there is a need in the industry for a sealing ring that will not continually rub on the valve seat and prematurely erode. It is also an objective of the present invention to provide a three-way valve wherein the sealing assembly is easily insertable and removable through the valve housing.

SUMMARY OF THE INVENTION It is a first object of the invention to provide a sealing assembly and a sealing ring for a three-way valve, wherein the sealing ring does not rub against the valve seats and where the sealing assembly may be easily displaced through the sealing seats for assembly and disassembly thereof.

This and other objects of the invention are obtained by a sealing assembly comprising two blocks with a sealing ring or gasket disposed in a groove between the blocks. The sealing ring is made of a resilient material and can expand radially. During movement of the sealing assembly, the blocks are spaced from each other and the sealing ring does not extend out beyond the periphery of the blocks. When the sealing assembly moves into a sealing position, the blocks are forced together, thereby exerting pressure on the sealing ring, so it expands radially and creates a strong seal against the sealing seats.

According to an aspect of the invention there is provided a three-way sealing valve comprising a sealing assembly comprised of two blocks. Within a groove between the blocks a resilient sealing ring is positioned. In a first position for movement of the sealing assembly, the blocks are slightly separated and no force is exerted on the sealing ring. This allows movement of the sealing assembly within the valve without the sealing ring rubbing or bearing against any surface. Upon placement of the sealing assembly in either of its sealing positions, the blocks are pressed together, thereby exerting pressure on the sealing ring. This pressure causes radial expansion of the sealing ring whereby it radially expands beyond the blocks to bear tightly against a respective sealing seat.

By this assembly, a strong, tight seal is produced, which can still be easily released when the valve is activated to move the sealing assembly to another position within the valve.

BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the invention and to see how it may be carried out in practice, an embodiment will now be described, by way of a non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 is a cross sectional view of a valve according to the present invention, in a first operative mode, a sealing assembly being in its lower sealing position; Fig. 2 is a cross sectional view of the valve according to the present invention in a second operative mode, the sealing means being in its upper sealing position; Fig. 3 is a cross sectional view of the valve according to the present invention the sealing assembly in an intermediary position; Fig. 4 is an enlarged, cross-sectional view of the sealing assembly in the position of Fig 1; and Fig. 5 is an enlarged, cross-sectional view of the sealing assembly in the sealing position of Fig. 2.

DETAILED DESCRIPTION OF THE INVENTION In Figs. 1, 2 and 3, a three-way control valve, generally designated 10, is illustrated, comprising a housing 11 in which arrow 12 represents the direction of flow of the fluid, between a flanged inlet port 14 and a flanged outlet port 16. However, it is appreciated that the fluid may flow in any direction, e.g. in a reverse direction (from port 16 to port 14), or between any one of ports 14 and 16 and a third, so-called back-flush/drain port 18, and it is only for purposes of illustration that the fluid is shown as flowing from left to right in the drawings. Furthermore, port 18 may be used for other purposes rather then back-flushing.

Two sealing ports 20 and 22 are formed within the housing, as will be hereinafter described. When a sealing assembly 24 is in sealing engagement at port 22 (a first sealing position), the valve 10 may be said to be open (Fig. 1) and a fluid flow path is formed between the inlet port 14 to the outlet port 16 via the sealing port 20. The direct flow from the inlet port 14 to the outlet port 16 is closed when the sealing assembly 24 is in sealing engagement with sealing port 20 (Fig. 2). In this position (second sealing position) the valve 10 may be said to be closed and there is flow communication between the outlet port 16 and the back-flush/drain port 18 via sealing port 22 to permit back flushing or other cleaning operations, as is well known in the industry.

However, it is to be appreciated that the valve may be otherwise oriented such that respective positions of the sealing assembly correspond with other positions of the valve. For example, the drain port may be defined as an inlet port or as an outlet port, etc.

In either of the open and closed position (respectively referred to as first and second positions) of Fig. 1 and 2, the sealing assembly 24 sealingly bears against the corresponding sealing port 20 or 22, as will become apparent hereinafter.

The sealing assembly 24 is carried and supported by a stem 26 which transports the sealing assembly back and forth within the valve 10 between sealing port 20 and sealing port 22. The sealing assembly 24 comprises two blocks 30 and 32 mounted on the stem 26 and retained by a top stopper spacer/washer 40 and secured from below by a nut 38, whereby the blocks are prevented from moving along the length of the stem by more than a small amount.

Each of blocks 30 and 32 has a groove in their facing surfaces which when the blocks are placed together, form a circular channel 34 (which in the particular embodiment has a T-like cross-section) around the periphery of the blocks at the faces where the blocks adjoin. Within the circular channel 34, a resilient or elastic sealing ring or gasket 36 is placed, made of an elastic/resilient material. At an uncompressed state, being the normal state of the sealing assembly, the sealing ring 36 guarantees the existence of a clearance/gap 76 (best seen in Fig. 5) between the - 5 - 155603/2 blocks 30 and 32, and the sealing ring 36 substantially does not radially project beyond the blocks. It is apparent that the sealing ring 36 has a thickness greater then the distance between the two facing surfaces of the channel 34 formed between the blocks 30 and 32.

The sealing ring 36 is shown in the particular embodiment as having a T-like cross-section, a head portion of which being received within corresponding receiving recesses 35A and 35B (Fig. 4 and 5), to grip the sealing ring and increase the effective pressure applied onto the sealing ring, as will become apparent hereinafter. However, the sealing ring 36 may have other cross-section shapes, e.g. a triangle, a trapezoid, etc.

A flexible control diaphragm 42 is clamped between a support flange 44 and a cover member 46 of the housing of the valve 10. As is known in the industry, bolts 48 are typically used to secure the cover member 46 on to the housing 11 to close the valve 10. An upper portion 50 of the stem 26 is coupled to the control diaphragm 42, extending via a diaphragm support disc 52.

The central portion of the diaphragm 42 is supported between the diaphragm support disc 52 extending below the diaphragm 42 and mounted on a shoulder of the upper portion 50 of the stem 26, and a second rigid disk 54 mounted above the diaphragm. A nut 56 is fastened to a threaded tip of the upper portion 50 of the stem 26 and, by this means, the disks 52 and 54 support the diaphragm 42 securely between them.

In the present example, the illustrated valve is a double chambered control valve, comprising a first control chamber 58 formed above the diaphragm 42, with one or more control ports 60 for connecting to a hydraulic control line (not shown). Below the control diaphragm 42, a second control chamber 62 is provided and it is connected via one or more control ports 64 to a hydraulic control line (not shown). However, in some cases the control fluid may be pneumatic rather hydraulic.

A coiled spring 66 biases the control diaphragm 42 and the associated disks 52 and 54 to maintain them in a normally open position (Fig. 1) in which the valve 10 is open to allow fluid flow from the inlet port 14 to the outlet port 16. However, it is appreciated that in addition to or instead of spring 66, the control diaphragm 42 may be hydraulically (or pneumatically) controlled via control ports 60.

The design of the coiled spring 66 is such that it applies a force that is less than the hydraulic force applied by a pressurized fluid on the bottom face of the control diaphragm 42. To open the valve 10, the second control chamber 62 is vented through control ports 64 and under the biasing effect of the coiled spring 66, or with the assistance of a control signal applied on the top face of the control diaphragm 42 via control ports 60, diaphragm 42 and the associated disks 52 and 54 are displaced into the first position as of Fig. 1, whereby the stem and articulated sealing assembly 24 are displaced downward within the valve 10. This effectively moves the sealing assembly 24 from sealing port 20 to sealing port 22. The valve 10 is now open and fluid can now flow from the inlet port 14 through the sealing port 20 to the outlet port 16. In this position the drain 18 is closed.

Applying pressurized control fluid through control ports 64, and climinishment of the hydraulic control signal via control ports 60, allows the force by the pressurized fluid on the bottom of the diaphragm, to move the control diaphragm 42 upward back to its closed position (Fig. 2), thereby causing the sealing means 24 to move back to sealing port 20 and thereby effectively again closing the valve 10. It is however appreciated that the first control chamber 58, formed above the diaphragm 42, may be normally vented i.e. not connected to control line. Spring 66 may be omitted as well.

The sealing port 20 has a circular cross-section and is provided with a sealing seat 68 in the form of a ring fixed onto a shoulder 70 of the valve housing. In similar fashion, the sealing port 22 has a circular cross-section and is provided with a sealing seat 72 in the form of a ring fixed onto a shoulder 74 of the valve housing 11.

Housing 11 is provided with a bottom stopper in the form of radially extending ribs 78, to limit downward displacement of the sealing assembly 24, and an upper stopper 79 is provided in the form of an annular seat extending from the support flange 44. The arrangement is such that downward displacement of the sealing assembly 24 (Figs. 1 and 4) entails butting engagement of the block 32 with the bottom stopper 78, whereby the top block 30 is pressed against the bottom block 32, resulting in closing the gap 76 therebetween and compressing the sealing ring 36, whereby it is forced to radially project into sealing engagement with the sealing seat 72 of the sealing port 22.

To close the valve 10 (Fig. 2), the stem 26 is moved upward and sealing assembly 24 is displaced upwards. The top block 30 abuts against the upper stopper 79 and upward force on the bottom block 32 by the stem 26 at nut 38 causes it to press against the top block 30, resulting in closing the gap 76 between the blocks. The sealing ring 36 is thus compressed causing it to radially project into sealing engagement with the sealing seat 68 of the sealing port 20.

In an intermediary position of the sealing assembly 24 (Figs. 3 and 5), the blocks 30 and 32 are slightly separated and no force is exerted on the sealing ring 36, whereby the sealing ring does not radially project from the blocks. This allows axial displacement of the sealing assembly 24 within the valve 10 without the sealing ring 36 rubbing or bearing against any surface, namely sealing ports 20 and 22.

Upon displacement of the sealing assembly 24 in either of the sealing positions (as in Figs. 1, 2 and 4), the blocks 30 and 32 are moved together and pressed against each other, thereby exerting pressure on the sealing ring 36. This pressure causes radial expansion of the resilient or elastic sealing ring 36 and the sealing ring radially expands beyond the blocks 30 and 32 to bear tightly against a respective sealing seat 68 or 72. By this arrangement, a strong, tight seal is produced, which can still be easily released when the valve 10 is activated to move the sealing assembly 24 to another position within the valve.

Figs. 4 and 5 show enlarged views of the sealing assembly 24 and illustrate how it operates. In the non-sealing position (Figs. 3 and 5), the blocks 30 and 32 are slightly separated by a gap 76. Generally the gap 76 is small in the order of about 1 millimeter. There is no force exerted on the sealing ring 26 and it resides completely with the channel 34 and does not extend beyond the periphery of the blocks 30 and 32. This allows the sealing assembly 24 to move within the valve 10 without the sealing ring 26 rubbing against any surface. As a result, the sealing ring 26 does not erode and its sealing effectiveness can be maintained for a much longer useful life.

Once the sealing assembly 24 is moved into one of the sealing ports 20 or 22 and bears tightly against the respective sealing seat 68 or 72, the blocks 30 and 32 are pressed together. This causes pressure on the sealing ring 36 resulting in radial expansion so as to maintain a strong, complete, tight seal at sealing seat 68 or 72 (Figs. 1, 2 and 4).

When it is time to again change the valve position, the blocks 30 and 32 are first separated to relieve pressure on the sealing ring 36, so the sealing ring recedes into the channel 34 and again the blocks can move freely without the sealing ring rubbing on any surface.

As the sealing assembly 24 moves up in the valve, upon entering the sealing port 20, the top surface of the top block 30 will engage the upper stopper 79 and thus exert force against the blocks. It is due to this force that the blocks 30 and 32 are pushed together and pressure is exerted on the sealing ring 36. By means of this pressure, the sealing ring expands radially and engages the sealing seat 68.

In a similar manner, the blocks 30 and 32 are pushed together when the sealing means 24 enters the other sealing port 22. Here, the lower block 32 bears against the immovable stopper 78 and this forces the blocks together and causes radial expansion of the sealing ring (Fig. 4).

As the sealing assembly 24 moves away from either of the stoppers, there is no longer any force on the blocks. As a result the sealing ring 36 contracts back to its normal size and position and does not extend out beyond the blocks (Fig. 5).

As there is some spacing between the washer 40 and the top block 30, there is room for some play or movement between the blocks to permit this compression. Generally, this play is very minimal and is just enough to allow a small gap of about 1 milliliter between the blocks.

Although an embodiment has been described and illustrated with reference to some drawings, it will be appreciated that many changes may be made therein without departing from the general spirit and scope of the invention, mutatis, mutandis.

It is however to be appreciated that other types of valves may utilize the sealing assembly of the present invention. For example, the valve may be of the type comprising a single control chamber extending above the diaphragm, whilst the lower control chamber is in fact in flow communication with the inlet port of the valve.

Claims (10)

1. 0 - 155603/2

2. A sealing assembly according to claim 1, further comprising a displacement mechanism for moving the sealing assembly within the valve between the sealing positions and for moving said blocks together and for separating them; whereby when said displacement mechanism is activated the blocks slightly separate from ¾ zy one another by the small gap; and, when the sealing assembly is stationary in one of its sealing positions, said displacement mechanism pushes said blocks together, thereby exerting pressure on the sealing ring to cause radial expansion thereof whereby the sealing ring radially expands beyond the blocks and engages a sealing iX. \ * seat of the valve.

3. A sealing assembly according to Claim 2, wherein the displacement mechanism comprises a stem having a first end onto which said sealing assembly is secured; and an actuator connected to a second end of said stem.

4. A sealing assembly according to Claim 3, wherein the actuator includes first and second control chambers through which there is a controlled flow of fluid; and a deformable control diaphragm located between said control chambers.

5. A sealing assembly according to Claim 4, wherein the actuator further comprises a biasing spring pressing against the control diaphragm.

6. A sealing assembly according to claim 1, wherein the sealing ring has an annular inner portion gripped within corresponding recesses of the sealing blocks. £ 6

7. A sealing assembly according to claim 6, wherein the sealing ring has a T- like cross-section, a leg portion thereof radially outwardly extending.

8. A sealing assembly according to claim 1, wherein the groove has a T-like cross-section, a leg portion thereof radially outwardly extending.

9. A sealing assembly according to claim 1, wherein the sealing ring has a thickness greater then the distance between two facing surfaces of the groove formed between the blocks.

10. A sealing assembly according to claim 1, wherein the diameter of the sealing radial expansion of the sealing ring and the sealing ring radially expands beyond the blocks to sealingly engage said sealing seat of a respective sealing port. 13. A three way valve according to claim 12, wherein the displacement mechanism comprises a first displacement stage whereby the sealing assembly is 5 displaced to and from said first sealing port and said second port, and a second stage for engaging the blocks and slightly separating them, respectively. 14. A three way valve according to Claim 12, wherein the displacement mechanism comprises a stem having a first end onto which the sealing assembly is secured; and, an actuator connected to a second end of said stem. 10 15. A three way valve according to Claim 11, wherein the actuator comprises first and second control chambers through which there is a controlled flow of fluid; and a movable diaphragm located in said control chambers, said diaphragm being articulated to the stem carrying the sealing assembly. 16. A three way valve according to Claim 15, wherein the actuator further 15 comprises a biasing spring pressing against the control diaphragm. 17. A three way valve according to Claim 12, wherein the sealing ring has an annular inner portion gripped within corresponding recesses of the sealing blocks. 18. A three way valve according to Claim 17, wherein the sealing ring has a T- like cross-section, a leg portion thereof radially outwardly extending. 20 19. A three way valve according to Claim 12, wherein the groove has a T-like cross-section, a leg portion thereof radially outwardly extending. 20. A three way valve according to Claim 12, wherein the sealing ring has a thickness greater then the distance between two facing surfaces of the groove formed between the blocks. 25 21. A three way valve according to Claim 12, wherein the diameter of the sealing ring at its un-pressurized state is lesser then the diameter of the sealing seat. 22. A three way valve according to Claim 12, wherein at the first sealing position a first one of the two blocks bears against a first stopper of the housing and whereby a second one of the blocks is pressed against said first block; and where at the second sealing position said second block bears against a second stopper of the housing and whereby the first block is pressed against said second block. For the Applicants, \\Doc-srv\Doc\l\4\01431352\4-01.Doc/27/04/2003