WO2010086628A1

WO2010086628A1 - Fluid flow governor

Info

Publication number: WO2010086628A1
Application number: PCT/GB2010/000168
Authority: WO
Inventors: Gareth Black
Original assignee: Crane Ltd
Current assignee: Crane Ltd
Priority date: 2009-02-02
Filing date: 2010-02-02
Publication date: 2010-08-05
Anticipated expiration: 2011-08-02
Also published as: GB0901626D0

Abstract

A fluid flow governor comprises a housing including a main body (1) defining a fluid flow inlet (3), a fluid flow outlet (4) and an internal cavity therebetween. A valve assembly is located within the housing cavity for controlling fluid flow from the inlet to the outlet to regulate fluid pressure at the outlet. The valve assembly (5) is sealed with respect to the cavity by an annular resilient seal member (7, 8) located in a respective annular gap defined between a cylindrical outer surface of the valve assembly (5) and a cylindrical wall surface defined by the cavity.

Description

Fluid Flow Governor

The present invention relates to a fluid flow governor, and particularly, but not exclusively, to a gas flow governor for regulating gas pressure at its outlet as gas pressure at its inlet fluctuates.

A fluid flow governor is a type of fluid flow valve which regulates or "governs" the outlet pressure of a fluid flowing through the governor. For instance gas flow governors may be installed in a gas service pipe to ensure that gas supplied to a downstream property or appliance is maintained within a pre-determined range (or at a pre-determined value) despite changes in supply pressure upstream of the governor as pressure in the gas mains pipe fluctuates.

One known type of gas flow governor is disclosed in UK Patent No. GB2317672 and comprises a diaphragm controlled valve assembly mounted within a governor body between a gas flow inlet and gas flow outlet defined by the body. The valve assembly is secured within the body by a cover which is crimped around the body and supports a spring loaded adjustment assembly which is operable to set the desired outlet pressure. The valve assembly is sealed within the body by three O- ring seals which are energised as the cover is crimped to the body. In particular a first O-ring seal is clamped between the cover and the valve assembly (to seal the valve assembly with respect to the cover) and second and third O-ring seals are clamped between the valve assembly and the body (to seal the valve assembly with respect to the body) as the cover and body are forced together.

It is an object of the present invention to provide a fluid flow governor with an improved seal arrangement.

According to the present invention there is provided a fluid flow governor comprising a housing including a main body defining a fluid flow inlet, a fluid flow outlet and an internal cavity therebetween, a valve assembly located within said housing cavity for controlling fluid flow from the inlet to the outlet to thereby regulate fluid pressure at the outlet wherein the valve assembly is sealed with respect to said cavity by at least a first annular resilient seal member located in a respective annular gap defined between a first substantially cylindrical outer surface of the valve assembly and a first substantially cylindrical wall surface defined by the cavity.

In contrast to the prior art acknowledged above, the resilient seal member of the present invention is subject to substantially radially compression and is energised simply by location of the valve assembly within the housing cavity. In particular, no additional clamping force is required from a cap or any other component of the fluid flow governor in order to energise the seal. With the present invention the integrity of the seal is more reliably established and maintained than with the prior art discussed above. It is preferable that there is a second annular seal member similarly located within an annular gap defined between a cylindrical surface of the cavity and a cylindrical surface of the valve assembly. This, and other preferred and advantageous features of the invention are described in more detail below.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which:

Fig 1 is a perspective view of a gas flow governor in accordance with the present invention;

Fig 2 is an exploded view of the gas flow governor of Fig 1 ;

Fig 3 is an exploded view of a valve assembly of the gas flow governor of Figs 1 and 2;

Fig 4 is a cross section of the valve assembly of Fig 3. Figs 5a and 5b are perspective views of the assembled valve assembly;

Fig 6 is a cross section through the fully assembled fluid flow governor of Fig 1.

Referring to the drawings, figure 1 is a perspective view of a gas flow governor in accordance with an embodiment of the present invention. The illustrated governor comprises a main body 1 and a cap 2 which is secured to the body by crimping an upper edge of the body Ia around the circumference of the lid 2. The body 1 defines a gas supply inlet 3 and outlet 4.

Figure 2 is an exploded view of the governor of figure 1 revealing a diaphragm controlled valve assembly 5 and adjuster spring 6 which are held in position when the cap 2 is fitted to the body 1 by crimping open end Ia of the body around circumferential edge 2a of the cap.

The valve assembly 5 is fitted with first and second resilient O-ring seal members 7 and 8 which seal the valve member with respect to the body when the valve assembly is fitted into the body. In particular, the seals are energised simply by inserting the valve assembly 5 into the main body 1 without the requirement for any clamping load to be applied by the cap. This will be described in more detail below.

Referring to figure 3 (which is an exploded perspective view of the valve assembly 5) and figure 4 (which is an axial cross-section of the valve assembly 5), the valve assembly comprises a valve spindle 9 supported by a diaphragm assembly 10 which is mounted to a generally cylindrical tubular valve body 1 1 which is provided with a gas flow inlet 12 and outlet 13. The valve spindle 9 extends axially through the valve body 1 1 and has an enlarged head 13 which cooperates with a valve seat 14 defined within the outlet 13 of the valve body 1 1 by an inwardly extending annular flange. The enlarged head 13 of the spindle 9 is provided with an elastomeric shroud 13a (for instance fabricated from nitrile rubber or other suitable material) to ensure a gas tight seal is formed when the valve head 13 is seated on the valve seat 14.

The diaphragm assembly 10 comprises primary and secondary diaphragms 15 and 16 respectively which are separated by a first diaphragm support member 17 and diaphragm spacer 18. The primary and secondary diaphragms 15 and 16, diaphragm support plate 17, and spacer 18, are all annular having respective central apertures to receive the valve spindle 9. The valve spindle 9 extends thus through the valve assembly components which are secured between an annular shoulder 19 defined by the valve spindle 9 and a second diaphragm support member 20 which is snap fitted to the end of the valve spindle which extends from the primary diaphragm 15.

To assemble the valve assembly, the secondary diaphragm 16 is first fitted to the valve body 11 and is then clamped in place by the first diaphragm support member 17 which is a snap-fitted to the valve assembly body 11 - resilient lungs 17a clipping the member 17 to the body 1 1. As is best seen in figure 4, the outer periphery of the secondary diaphragm 16 is provided with a beaded rim portion 16a which is received within a complimentary annular groove 21 defined by a radially extending flange 22 of the valve body 1 1. This ensure a good seal between the secondary diaphragm 16 and the valve body 1 1. The valve spindle 9 is inserted through the outlet 13 of the valve body 1 1 and through central apertures defined by the secondary diaphragm 16 and diaphragm support member 17 respectively. Diaphragm spacer 18 is then fitted onto the spindle 9. The primary diaphragm 15 is then fitted onto the spindle and the assembly is completed by snap fitting the second diaphragm support member 20 to the end of the spindle 9 to clamp the valve assembly components together.

As best seen in figure 4, the inner periphery of the secondary diaphragm 16 is trapped between the diaphragm spacer 18 and the annular shoulder 19 defined by the valve spindle 9. Similarly, the inner periphery of the primary diaphragm 15 is trapped between the diaphragm spacer 18 and the second diaphragm support member 20. The outer periphery of the primary diaphragm 15 is provided with a beaded rim 15a which is received within an annular recess defined at the periphery of the diaphragm support plate 17. The first diaphragm support plate 17 has a generally dished configuration defining an annular wall 17b at its periphery, which together with the diaphragm spacer 18 ensures that an annular diaphragm chamber 23 is defined between the first diaphragm support member 17, secondary diaphragm 16 and the primary diaphragm 15.

Referring to figures 5a and 5b, the first and second O-ring seal members 7 and 8 are then fitted to the valve assembly prior to its installation in the main body 1 of the governor housing. The first O-ring seal member 7 is seated around the outer circumference of the cylindrical wall 17b of the first diaphragm support member 17 and the second O-ring seal member 8 is seated around the cylindrical outer surface of the outlet end of the valve body 11. The first O-ring seal 7 is located against an annular shoulder 17c extending radially from the cylindrical wall 17b and the second O-ring seal member 8 is located against an annular shoulder 1 1 a extending radially from the valve body 1 1.

Once assembled, the valve assembly 5 is inserted into a cavity Ib defined within the main body 1 as illustrated in figure 6. In particular, the first O-ring 7 is radially compressed in an annular gap defined between the first diaphragm support member wall 17b and a first inner cylindrical wall surface of the body cavity Ib to form a first seal, and the second O-ring seal member 8 is radially compressed in an annular gap defined between the valve body 1 1 and a second inner cylindrical wall surface of the body cavity Ib to form a second seal. It will thus be appreciated that the first and second seals are energised simply by insertion of the valve assembly 5 into the governor body 1, the first and second O- ring seal members 7 and 8 being compressed radially (with respect to the axis of the valve spindle 9) between outer cylindrical surfaces of the valve assembly 5 and inner cylindrical surfaces of the main body 1 respectively. No additional clamping force (and in particular no axial clamping force) is required to energise and maintain the integrity of the seals. Assembly of the governor is then completed by fitting the cap 2 to the main body

1 with the adjuster spring 6 trapped there between. In more detail, and again with reference to figure 6, the cap 1 supports an adjusting spindle 23 which carries a radially extending spring adjusting plate 24. The adjusting spindle 23 extends through a hole provided in the centre of an upper cylindrical portion 2b of the cap

2 and is sealed in respect thereto by an O-ring 25. The spring 6 is compressed between the adjusting plate 24 and the second diaphragm support member 20. The spring 6 is located between a central boss 20a defined on the upper surface of the second diaphragm support plate 20 and a central generally frusto-conical locating portion defined on the underside of the adjusting plate 24.

The cap 2 has a depending peripheral skirt portion 2a which seats within a surrounding peripheral portion Ia of the main body 1 which is then crimped around the cap to secure the cap 2 and the body 1 together (in figure 6 the assembly is shown prior to the crimping operation). The outer peripheral edge of the primary diaphragm 15 is clamped between the cap 2 and the first diaphragm support member 17 to ensure a good seal between the two. However, it will be appreciated that no axial clamping force is applied to either the first or second O- ring seal members 7 and 8, which instead are energised simply by location of the valve assembly 5 within the main body 1.

In operation, the governor according to the invention functions essentially in a known manner. That is, the adjuster spring exerts a downward force on the valve spindle 9 via the diaphragm plate 20 which acts to move the head 13 of the valve spindle 9 off the valve seat 14 allowing gas to flow from the governor inlet 3 to the governor outlet 4 through the valve body 11. The valve spindle 9 is designed such that upward force on the spindle generated by the inlet gas pressure acting on the secondary diaphragm 16 is at least substantially balanced by downward force on the spindle through the downward static pressure exerted on the head 13 of the spindle as gas flows to the outlet 3. The gas pressure at the outlet 3 generates an upward force on the valve head 13 tending to urge the spindle 9 upwards against the biasing force of the adjusting spring 6 until the forces are balanced. Downward force exerted on the spindle by the spring thus determines the desired pressure at the governor outlet 3. That is, should the inlet pressure increase, tending to increase the pressure at the outlet, the upward force on the valve spindle 9 will likewise increase moving the spindle upwards against the action of the spring 6 thereby reducing the size of the annular gap between the spindle head 13 and the valve seat 14 which in turn reduces the outlet pressure until force balance is once again reached between the outlet pressure and the biasing force of the spring. Similarly, should the inlet pressure drop tending to reduce the outlet pressure, force on the head 13 of the spindle 9 at the outlet decreases and the spindle will move downwards under the biasing force of the spring 6 to allow more gas to flow through the outlet thereby increasing the pressure at the outlet until balance is once again reached. In this way the outlet pressure is maintained at a pre-determined value (or within a pre-determined range of values) which is determined by the biasing force of the spring. The desired pressure can be adjusted by appropriate adjustment of the spring adjusting plate 24 along the adjustment spindle 23 thereby varying the degree of compression of the spring 6.

It will be understood that many detailed changes could be made to the embodiment of the invention described above. For instance, the wall portions which define the annular gaps within which the first and second O-ring seal members 7 and 8 are compressed may be defined by different portions of the valve assembly and governor body 1 respectively.

It will be appreciated that the embodiments of the present invention are not limited to gas flow governors intended for regulating natural gas supply pressure from a gas mains.. For instance, governors according to the present invention can be used to regulate the gas supply of pressure to individual gas appliances and similarly can be used in many industrial applications in which controlled gas supply pressure is required. Moreover, the invention is not limited to regulating gas flow, but can be used with any fluid, including liquids. Appropriate applications of governors according to the present invention will be readily apparent to the appropriately skilled person.

Claims

1. A fluid flow governor comprising: a housing including a main body defining a fluid flow inlet, a fluid flow outlet and an internal cavity therebetween; a valve assembly located within said housing cavity for controlling fluid flow from the inlet to the outlet to thereby regulate fluid pressure at the outlet; wherein the valve assembly is sealed with respect to said cavity by at least a first annular resiliant seal member located in a respective annular gap defined between a first substantially cylindrical outer surface of the valve assembly and a first substantially cylindrical wall surface defined by the cavity.

2. A valve assembly according to claim 1 , wherein the housing includes a cap which is secured to the main body and the first resilient seal member is located so as to prevent fluid leakage from the inlet to the cap.

3. A fluid flow governor according to claim 1 or claim 2, comprising a second resilient annular seal member located in a respective annular gap defined between a second substantially cylindrical outer surface of the valve assembly and a second substantially cylindrical wall surface defined by the cavity.

4. A fluid flow governor according to claim 2, wherein the second resilient valve member is located to prevent fluid leakage from the inlet to the outlet between the valve assembly and the respective cavity wall surface.

5. A fluid flow governor according to any preceding claim, wherein the valve assembly comprises a valve spindle supported by a diaphragm assembly and extending through a generally cylindrical valve body defining an inlet which aligns with the inlet of the housing body and an annular outlet defined between a sealing surface provided at an enlarged head of the valve spindle and a valve seat defined by an inner annular portion of the valve body.

6. A fluid flow governor according to claim 5, where the valve spindle head is spring biased away from said valve seat to define an annular fluid flow passage from the inlet to the outlet.

7. A fluid flow governor according to claim 5 or 6, wherein the diaphragm assembly includes a first diaphragm support member comprising a generally annular disc provided with a generally cylindrical wall at its outer circumferential periphery, and wherein said first substantially cylindrical onto the surface of the valve assembly is defined by said cylindrical wall.

8. A fluid flow governor according to anyone of claims 5 to 7, wherein the valve assembly comprises a second diaphragm support member, the valve spindle extending through a central aperture of both the first and second diaphragm support members and through a generally cylindrical diaphragm spacer located between the first and second diaphragms.

9. A fluid flow governor according to claim 8, wherein an inner peripheral edge of the first diaphragm is trapped between the second diaphragm support plate and the spacer and an inner peripheral edge of the second diaphragm is trapped between the spacer and an annular shoulder defined by the valve spindle.

10. A fluid flow governor according to claims 8 or 9, wherein an outer peripheral edge of the first diaphragm is trapped between a flange extending radially from the cylindrical peripheral wall of the first diaphragm support member and the cap, and an outer peripheral edge of the second diaphragm is trapped between the first diaphragm support member and a radially outwardly extending flange of the generally cylindrical valve body.

1 1. A fluid flow governor according to anyone of claims 8 to 10, wherein the first diaphragm support member is a snap fit to the valve body and the second diaphragm support member is a snap fit to the valve spindle to secure the components of the valve assembly together.

12. A fluid flow governor according to any preceding claim, wherein the housing includes a cap and where the cap has a peripheral depending cylindrical wall portion of the cap is received within a circumferential portion of the valve body which is crimped to the cap to secure the two together.

13. A fluid flow governor according to claim 12, wherein the cap supports a spring loaded valve adjustment assembly comprising a compression spring which acts on the diaphragm assembly to bias the valve spindle towards a position in which a fluid flow gap is maintained between the head of the valve spindle and the valve seat defined by the valve body against opposing force on the valve spindle generated by fluid pressure at the outlet of the main body.

14. A fluid flow governor according to claim 13, wherein the compression of the spring is adjustable to vary the magnitude of the regulated pressure at the outlet.