WO2005088263A1

WO2005088263A1 - Valve assembly

Info

Publication number: WO2005088263A1
Application number: PCT/SE2005/000306
Authority: WO
Inventors: Anders Engelbrektsson
Original assignee: Tour And Andersson Ab
Priority date: 2004-03-16
Filing date: 2005-03-03
Publication date: 2005-09-22
Also published as: CN1973186A; GB2412152A; GB2416385B; EP1725838A1; GB2412152B; CN100424476C; HK1103793A1; GB0519413D0; GB0405814D0; GB2416385A

Abstract

A valve assembly for controlling the flow of fluid therethrough is disclosed. The valve assembly defines a conduit for fluid, and comprises a valve for controlling the flow of fluid, first and second sensor ports for receiving measuring instruments to measure the pressure or temperature of fluid at upstream and downstream positions in the conduit, and a flow venturi for providing a pressure drop between the upstream and downstream positions.

Description

Naive Assembly

The present invention relates to a valve assembly for controlling the flow of fluid in fluid- systems.

Naive assemblies can be used to measure and control the flow of fluid in fluid system, such as, by way of example only, heating, cooling, ventilation and air conditioning systems. The rate of flow of fluid through such a valve assembly is determined by measuring the pressure drop across a constriction in the valve assembly. In many applications the pressure drop can be measured across a measuring flange or venturi.

Flow Venturis can be used to determine the rate of flow through a valve assembly by taking a first pressure measurement from a region in the valve assembly upstream of the constriction of the venturi. A second pressure measurement is also taken downstream of the constriction of the venturi, and is typically taken from a region at the venturi throat. The measurements can then be compared in a measuring apparatus connected to the valve housing. The measured pressure drop can then be used to determine the flow rate. The flow rate through the valve assembly can then be adjusted as desired, by opening or closing a valve in the assembly.

Some valve assemblies utilise a separate venturi that can be inserted into the valve assembly, and subsequently removed. However, there are problems associated with valve assemblies that utilise a separate flow venturi. For example, it is possible for a valve assembly to be tampered with by removing the flow venturi and changing it for a different flow venturi. This can lead to inaccuracies in calculating the flow rate through the valve assembly if it is not known which flow venturi has been inserted. Further, it is possible for such flow Venturis to be inserted incorrectly into the valve assembly. For example, the flow venturi may be placed too far down the valve assembly, not far enough, or it may even be inserted in the valve assembly backwards. The incorrect placement of the flow venturi in the valve assembly can lead to inaccuracies in calculating the flow rate through the valve assembly. A further problem with such separate, insertable flow Venturis is that O-rings or other sealing members that provide a tight seal between the flow venturi and the inner surface of the valve assembly in which the flow venturi is inserted, can become damaged as the flow venturi is inserted into the valve assembly. This can result in inaccuracies in the pressure drop measured, in which case the calculated rate of flow through the valve assembly will be inaccurate.

Another problem associated with the use of a flow venturi is that the measured pressure of the fluid passing through the venturi can be inaccurate. Again, any inaccuracy of the measured pressure can result in the calculated rate of flow through the valve assembly being inaccurate.

Therefore, the present invention addresses deficiencies in valve assemblies, particularly related to flow Venturis.

According to a first aspect of the invention, there is provided a valve assembly for controlling the flow of fluid there through which comprises a body having an inlet and an outlet at opposed ends of the body, a conduit extending between the inlet and the outlet, an upstream channel and a downstream channel providing fluid connection between the conduit and respective first and second chambers for respective first and second sensor ports, a valve operable to control the flow of fluid through the conduit and a flow venturi, insertable into a site in the conduit, the flow venturi having a throat portion, and wherein when the flow venturi is positioned at the site, the upstream channel provides fluid communication with fluid upstream of the throat portion, and the downstream channel provides fluid communication with fluid at, or downstream of, the throat portion and wherein the flow venturi and a part of the body provide between them a latch mechanism which locks the flow venturi in the body and wherein the latch is inaccessible, thereby preventing the venturi from being removed.

Once the flow venturi has been located at the site in the bore of the valve assembly it is not possible to gain access to the latch mechanism to remove the flow venturi from the body. Therefore, the flow venturi cannot be changed for a different flow venturi, and therefore eliminates the problem of tampering which can introduce inaccuracies in the calculation of the rate of flow of fluid through the valve assembly.

A user of the valve assembly will know when the flow venturi has been inserted correctly into the valve assembly. This is because the latch mechanism will lock the flow venturi in the body, when the flow venturi has been inserted correctly at its site in the body. Therefore, if the flow venturi has not been inserted correctly, the user will be able to remove the venturi, and they will therefore know that it is not located correctly at its site.

Preferably, the first and second chambers for first and second sensor ports are configured so that their axes are perpendicular to the axial length of the body. However, it will be appreciated that their axes need not be perpendicular to the axial length of the body. More preferably, the upstream and downstream channels provide a fluid connection between the first and second chambers, wherein the channels extend transversely through the body, between the chambers and the conduit. This configuration can be advantageous because it provides a simple, non tortuous fluid connection between the conduit and first and second chambers, which can simplify the manufacturing process of the valve assembly.

The first and second chambers are configured to receive respective first and second sensor ports. Preferably, the first and second chambers have a screw thread on their walls for engaging a cooperating screw thread on the ends of the respective first and second sensor ports. However, it will be appreciated that other connector mechanisms can be used to secure the first and second sensor ports to the first and second chambers. For example, a bayonet fitting maybe used instead of a screw thread fitting.

The valve can be any valve that is operable to control the flow of fluid through the conduit. For example, the valve may be a ball valve that is rotatably mounted in the body so that axis about which it rotates is perpendicular to the longitudinal axis of the conduit. Therefore, rotation of the ball valve in one direction opens the valve, and rotation of the ball valve in the opposite direction closes the valve. Preferably, the valve comprises a plug and aperture arrangement. Preferably, the aperture is defined by an annular wall extending around and partially across the conduit, and in which the aperture is capable of receiving the plug which is mounted on an actuator for translating the plug in a direction co-axial with the aperture. Preferably, the wall extends across the conduit so that the angle between (a) the axis of the aperture, and (b) the longitudinal axis of the conduit is 45°. However, it will be appreciated that the angle between (a) and (b) need not be 45°. Preferably, the angle between (a) and (b) is in the range of angles between 5° and 90°. More preferably, the angle between (a) and (b) is in the range of angles between 20° and 80°. Especially preferably, the angle between (a) and (b) is in the range of angles between 30° and 50°. Preferably, the actuator upon which the plug is mounted is a linear actuator. Preferably, the plug is mounted on a spindle arrangement which can be rotated to translate the plug towards and away from the aperture.

The inlet of the body can be any conventional inlet port that is capable of being connected to an inlet hose, pipe or conduit of a fluid system. The outlet of the body can be any conventional outlet port that is capable of being connected to an outlet hose, pipe or conduit of a fluid system. The inlet and outlet can be identical in configuration. Preferably the inlet and outlet each have an internal screw thread for engagement with a co-operating screw thread on the end of each of the inlet and outlet hoses. However, it will be appreciated that any mechanism may be used to connect the inlet and outlet of the body to the inlet and outlet hoses. For example, the inlet and outlet may be appropriately shaped and sized to receive the inlet and outlet hoses by simple sliding engagement, so that the inlet and outlet hoses are a snug fit within the inlet and outlet.

The latch mechanism can be provided by a first formation abutting against a second formation. The latch mechanism can comprise two formations, wherein at least one of the formations has a chamfered surface. At least one of the formations can be resiliently flexible, movable, displaceable or deformable, thereby permitting one formation to be slid over or past the other. The latch mechanism can comprise a plurality of latches. A latch, or a plurality of latches, can be provided on the body and/or on the flow venturi. A single recess or a plurality of recesses can be provided in the body and/or the flow venturi. The recess can be provided by a formation or formations in or on the body and/or flow venturi.

Preferably, the latch mechanism comprises a latch, and a recess for receiving the latch. Preferably, the latch is biassed towards the recess, so that the latch is received within the recess when the flow venturi is positioned at the site.

Preferably, the flow venturi includes the latch, the latch being biassed outwardly from an outer surface of the venturi to engage against an inner surface of the body as the flow venturi is inserted in the conduit towards the site. This can be advantageous as the latch will scrape along the inner surface of the body as the flow venturi is inserted, thereby removing any unwanted material from the inner surface of the body. Especially preferably, the latch is located towards the downstream end of the flow venturi so that any unwanted material is removed from the inner surface of the body before any parts of the flow venturi that may be damaged by such material pass across such material. For example, O-rings may be provided on the exterior surface of the venturi which may be damaged by burrs or other unwanted material present on the inner surface of the body, as the O-rings are slid passed the burrs. Especially more preferably, the latch is downstream of the downstream channel. Therefore, any burrs that are left as a result of the creation of the upstream and downstream channels will be removed from the inner surface of the body by the latch as it slides past the upstream and downstream channels.

Preferably, the latch extends substantially circumferentially around the outer surface of the flow venturi, and the recess extends circumferentially around the surface of the conduit. Preferably, the latch comprises a locking ring. Preferably the locking ring is a resiliently compressible split ring, such as a C-ring. Preferably, the split "C" ring is resiliently compressible so that it can be compressed into a closed state in which the ends of the split "C" ring are abutting, and in which when the split "C" ring is in its compressed state, the split "C" ring is biassed outwardly to an expanded, uncompressed state in which the ends of the split "C" ring are not together. However, it will be appreciated that the ends of the split "C" ring do not need to be abutting when the split "C" ring is in its compressed. For example, it can be sufficient that when the split "C" ring is in its compressed state, the length of the arc between the ends of the split is smaller than when the split "C" ring is in its expanded, uncompressed state. Preferably, the locking ring is made of a metallic or alloy material. Preferably, the locking ring is made of a non- corrosive or corrosive resistant material, such as plastics, reinforced plastics, or stainless steel. However, it will be appreciated that the locking ring can be made of other suitable materials having the desired characteristics, such as steel.

Preferably, the flow venturi is made of a metallic or alloy material such as brass or steel. More preferably, the flow venturi is made of a dezincification resistant brass alloy, or a non-corrodible plastic material. However, it will be appreciated that the flow venturi can be made of other suitable materials such as plastics, reinforced plastics, or other materials which can be suitably be combined with the valve body. Preferably, the flow venturi and the valve body are made from the same material.

Preferably, the upstream and downstream chambers are upstream of the valve. However, it will be appreciated that the upstream and downstream chambers can be downstream of the valve.

Preferably, the site for the flow venturi is upstream of the valve. However, it will be appreciated that the site for the flow venturi can be downstream of the valve.

O-rings can be provided on the exterior surface of the flow venturi to provide a tight seal between the flow venturi and the inner surface of the body. Preferably, the O-rings are made of a suitable rubber or plastic material which can take the shape of the surface against which it is compressed. However, it will be appreciated that any type of sealing member or mechanism can be used to prevent such leakage.

Preferably, the flow venturi has an inlet portion upstream of the throat portion, the inlet portion having a plurality of channels providing communication between fluid at the inlet portion and the upstream channel, and in which the flow venturi has a plurality of channels providing communication between fluid downstream of the inlet portion and the downstream channel.

Preferably, there are at least four channels providing communication between fluid at the inlet portion and the upstream channel, and at least four channels providing communication between fluid downstream of the inlet portion in the downstream channel. As will be appreciated, more or fewer than four channels can be provided at the inlet portion and more or fewer than four channels can be provided downstream of the inlet portion. For example, the number of channels provided at the inlet portion can be any of 2, 3, 4, 5, 6, 7 or 8. Preferably, the number of channels at the inlet portion is between 2 to 6. More preferably, the number of channels at the inlet portion is between 3 to 5. Further, the number of channels provided downstream of the inlet portion can be any of 2, 3, 4, 5, 6, 7 or 8. Preferably, the number of channels downstream of the inlet portion is between 2 to 6. More preferably, the number of channels downstream of the inlet portion is between 3 to 5. The provision of less than four channels can increase the simplicity of the manufacture such flow Venturis. The provision of more than four channels can increase the accuracy of the pressure of fluid measured. This can be due to the provision of more points at which the measuring instrument is in fluid connection with the fluid in the body. However, the provision of at least four channels at the inlet portion and at least four channels downstream of the inlet portion provides an increased accuracy of the average pressure of the fluid at the inlet portion and also downstream of the inlet portion. Therefore, the measured pressure of fluid at the inlet portion and downstream of the inlet portion is more accurate, therefore resulting in an increased accuracy of the calculation of the flow rate.

The plurality of channels downstream of the inlet portion can be provided at any point downstream of the inlet portion. Preferably, the plurality of channels downstream of the inlet portion are provided at the throat portion of the inlet portion. This can be advantageous as a more accurate measurement of the pressure flowing through the throat portion can be obtained than further downstream of the throat portion. Preferably, the flow venturi and body between them define a first slot providing fluid communication between a plurality of channels of the inlet portion and the upstream channel. Preferably, the flow venturi and body between them define a second slot providing fluid connection between the plurality of channels downstream of the inlet portion in a downstream channel. Preferably, the first and second slots are annular slots that extend around the circumference of the inlet portion and the part of the venturi downstream of the inlet portion respectively.

According to a further aspect of the present invention, there is provided a valve assembly for controlling the flow of fluid which comprises a body having an inlet and an outlet at opposed ends of the body, a conduit extending between the inlet and outlet, an upstream channel and a downstream channel providing fluid connection between the conduit and respective first and second chambers for respective first and second sensor ports, a valve operable to control the flow of fluid through the conduit and a flow venturi locatable at a site in the conduit, the flow venturi having: an inlet portion; a throat portion downstream of the inlet portion; a plurality of channels providing communication between fluid at the inlet portion and the upstream channel; and a plurality of channels providing communication between fluid downstream of the inlet portion and the downstream channel.

A more accurate measurement of the pressure of fluid passing through the flow venturi is provided by the plurality of channels which provide samples of fluid properties at different regions within the venturi when compared to existing flow Venturis. The provision of a plurality of channels between the chambers for the sensor ports and the fluid at the inlet portion of the flow venturi, gives rise to a more accurate calculation of the pressure of the fluid at that point. Further, the provision of a plurality of channels between the chambers for the sensor ports and the fluid downstream of the inlet portion of the flow venturi, gives rise to a more accurate calculation of the pressure of the fluid after it has entered the throat of the flow venturi. Therefore, a more accurate calculation of the pressure drop across the flow venturi can be obtained, giving rise to a more accurate calculation of the flow rate of fluid through the valve assembly. This is because an average pressure level of the fluid at inlet portion is obtained, and also an average pressure level of the fluid downstream of the inlet portion is obtained. This is in contrast to existing Venturis that provide only a single channel at the inlet portion and a single channel downstream of the inlet portion that allow only a single sample of the pressure of the fluid from those single channels to be measured.

The first and second chambers are configured to receive respective first and second sensor ports. Preferably, the first and second chambers have a screw thread on their walls for engaging a cooperating screw thread on the ends of the respective first and second sensor ports. However, it will be appreciated that other engaging mechanisms can be used to secure the first and second sensor ports to the first and second chambers. For example, a bayonet fitting may be used instead of a screw thread fitting.

The valve can be any valve that is operable to control the flow of fluid through the conduit. For example, the valve may be a typical ball valve that is rotatably mounted in the body so that axis about which it rotates is perpendicular to the longitudinal axis of the conduit. Therefore, rotation of the ball valve in one direction opens the valve, and rotation of the ball valve in the opposite direction closes the valve.

Preferably, the valve comprises a plug and aperture arrangement. Preferably, the aperture is defined by a annular wall extending across the conduit, and in which the aperture is capable of receiving the plug which is mounted on an actuator for translating the plug in a direction co-axial with the aperture. Preferably, the wall extends across the conduit so that the angle between (a) the axis of the aperture, and (b) the longitudinal axis of the conduit is 45°. However, it will be appreciated that the angle between (a) and (b) need not be 45°. Preferably, the angle between (a) and (b) is in the range of angles between 5° and 90°. More preferably, the angle between (a) and (b) is in the range of angles between 20° and 80°. Especially preferably, the angle between (a) and (b) is in the range of angles between 30° and 50°. Preferably, the actuator upon which the plug is mounted is a linear actuator. Preferably, the plug is mounted on a spindle arrangement which can be rotated to translate the plug towards and away from the aperture.

The inlet of the body can be any conventional inlet port that is capable of being connected to an inlet hose of a fluid system. The outlet of the body can be any conventional outlet port that is capable of being connected to an outlet hose of a fluid system. The inlet and outlet can be identical in configuration. Preferably the inlet and outlet each have an internal screw thread for engagement with a cooperating screw thread on the end of each of the inlet and outlet hoses. However, it will be appreciated that any mechanism may be used to connect the inlet and outlet of the body to the inlet and outlet hoses. For example, the inlet and outlet may be appropriately shaped and sized to receive the inlet and outlet hoses by simple sliding engagement, so that the inlet and outlet hoses are a snug fit within the inlet and outlet.

Preferably, there are at least four channels providing communication between fluid at the inlet portion and the upstream channel, and at least four channels providing communication between fluid downstream of the inlet portion in the downstream channel. As will be appreciated, more or fewer than four channels can be provided at the inlet portion and more or fewer than four channels can be provided downstream of the inlet portion. For example, the number of channels provided at the inlet portion can be any of 2, 3, 4, 5, 6, 7 or 8. Preferably, the number of channels at the inlet portion is between 2 to 6. More preferably, the number of channels at the inlet portion is between 3 to 5. Further, the number of channels provided at downstream of the inlet portion can be any of 2, 3, 4, 5, 6, 7 or 8. Preferably, the number of channels downstream of the inlet portion is between 2 to 6. More preferably, the number of channels downstream of the inlet portion is between 3 to 5. The provision of less than four channels can increase the simplicity of the manufacture such flow Venturis. The provision of more than four channels can increase the accuracy of the pressure of fluid measured. This can be due to the provision of more points at which the measuring instrument is in fluid connection with the fluid in the body. However, the provision of at least four channels at the inlet portion and at least four channels downstream of the inlet portion provides an increased accuracy of the average pressure of the fluid at the inlet portion and also downstream of the inlet portion. Therefore, the measured pressure of fluid at the inlet portion and downstream of the inlet portion is more accurate, therefore resulting in an increased accuracy of the calculation of the flow rate.

The plurality of channels downstream of the inlet portion can be provided at any point downstream of the inlet portion. Preferably, the plurality of channels downstream of the inlet portion are provided at the throat portion of the inlet portion. This can be advantageous as a more accurate measurement of the pressure flowing through the throat portion can be obtained than further downstream of the throat portion.

Preferably, the flow venturi and body between them define a, first slot providing fluid communication between a plurality of channels of the inlet portion and the upstream channel. Preferably, the flow venturi and body between them define a second slot providing fluid connection between the plurality of channels downstream of the inlet portion in a downstream channel. Preferably, the first and second slots are annular slots that extend around the circumference of the inlet portion and the part of the venturi downstream of the inlet portion respectively.

The flow venturi can be integral with the body. Preferably, the flow venturi is a separate piece to the body. Preferably, the flow venturi is insertable into the site in the conduit, wherein the flow venturi and a part of the body provide between them a latch mechanism which locks the flow venturi in the body and wherein the latch is inaccessible, thereby preventing the venturi from being removed.

The latch mechanism can be provided by a first formation abutting against a second formation. The latch mechanism can comprise two formations, wherein at least one of the formations has a chamfered surface. At least one of the formations can be resiliently flexible, movable, displaceable or deformable, thereby permitting one formation to be slid over or past the other.

The latch mechanism can comprise a plurality of latches. A latch, or a plurality of latches, can be provided on the body and/or on the flow venturi. A single recess or a plurality of recesses can be provided in the body and/or the flow venturi. The recess can be provided by a formation or formations in or on the body and/or flow venturi.

Preferably, the flow venturi includes the latch, the latch being biassed outwardly from an outer surface of the venturi to engage against an inner surface of the body as the flow venturi is inserted in the conduit towards the site. This can be advantageous as the latch will scrape along the inner surface of the body as the flow venturi is inserted, thereby removing any unwanted material from the inner surface of the body. Especially preferably, the latch is located towards the downstream end of the flow venturi so that any unwanted material is removed from the inner surface of the body before any parts of the flow venturi that may be damaged by such material pass across such material. For example, O-rings maybe provided on the exterior surface of the venturi which maybe damaged by burrs or other unwanted material present on the inner surface of the body, as the O-rings are slid passed the burrs. Especially more preferably, the latch is downstream of the downsfream channel. Therefore, any burrs that are left as a result of the creation of the upstream and downstream channels will be removed from the inner surface of the body by the latch as it slides past the upstream and downstream channels.

Preferably, the latch extends substantially circumferentially around the outer surface of the flow venturi, and the recess extends circumferentially around the surface of the conduit. Preferably, the latch comprises a locking ring. Preferably the locking ring is a resiliently compressible split ring, such as a C-ring. Preferably, the split "C" ring is resiliently compressible so that it can be compressed into a closed state in which the ends of the split "C" ring are abutting, and in which when the split "C" ring is in its compressed state, the split "C" ring is biassed outwardly to an expanded, uncompressed state in which the ends of the split "C" ring are not together. However, it will be appreciated that the ends of the split "C" ring do not need to be abutting when the split "C" ring is in its compressed. For example, it can be sufficient that when the split "C" ring is in its compressed state, the length of the arc between the ends of the split is smaller than when the split "C" ring is in its expanded, uncompressed state. Preferably, the locking ring is made of a metallic or alloy material. Preferably, the locking ring is made of a non- corrosive or corrosive resistant material, such as plastics, reinforced plastics, stainless steel . However, it will be appreciated that the locking ring can be made of other suitable materials having the desired characteristics, such as steel.

O-rings can be provided on the exterior surface of the flow venturi to provide a tight seal between the flow venturi and the inner surface of the body. Preferably, the O-rings are made of a suitable rubber or plastic material which can take the shape of the surface against which it is compressed. However, it will be appreciated that any type of sealing member or mechanism can be used to prevent such leakage. An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 shows a cross-sectional side view of a valve assembly according to the invention; and

Figure 2, shows a magnified view of a region of figure 1, at which the flow venturi is located in the valve assembly.

Referring to the drawing, figure 1 shows the valve assembly 1 according to the present invention in isolation from a fluid system in which the valve assembly may be used.

The valve assembly generally comprises: an elongate body 2, having an inlet port 4 and an outlet port 6 at opposite ends of the body for connection to inlet and outlet hoses of a fluid flow system (not shown); a valve mechanism designated generally by 10, mounted towards the outlet port 6, the valve mechanism being operable to control the flow of fluid through the body 2; an upstream sensor port 22, and a downstream sensor port 24 secured to the body 2 towards the inlet port 4, each sensor port being capable of receiving an instrument for measuring the pressure of fluid at upstream and downstream positions of fluid flowing through the body; and a flow venturi 30 inserted in the body 2 for causing a pressure drop between the upstream and downstream positions.

The body of the valve assembly can be made from materials such as dezincification resistant brass alloys, or non-corrodible plastic materials. A suitable body for that can be used with the present invention is an elongated version of the valve assembly body provided under name of STAD by Tour & Anderson AB of Ljung, Sweden. The body of the valve assembly in the present embodiment is elongated on the inlet side of the body, upstream of the valve. However, it will be appreciated that the elongation of the body can be on the outlet side of the body, downstream of the valve. The provision of an elongated body can be advantageous as it aids accommodation of a flow venturi in the conduit of the body, by providing extra space within which the flow venturi can be located. Further, it can allow for the sensor ports to be secured to the prolonged part of the body, away from the valve part of the body, which can simplify the manufacturing process of the valve assembly.

The inlet port 4 and the outlet port 6 have screw threads 32, 34 on their internal surface for engagement with cooperating screw threads on the inlet and outlet hoses of the fluid flow system (not shown). A conduit, generally designated by reference numeral 8, extends between the inlet and outlet ports 4, 6, the conduit defining a flow path for fluid between the inlet and outlet ports.

The body 2 has a wall 12 extending across the conduit 8, the wall splitting the conduit 8 into an upsfream conduit chamber 36 proximal to the inlet port 4, and a downstream conduit chamber 38 proximal to the outlet port 6. The wall 12 extends across the conduit 8 at an angle of 45°. An aperture 14 in the wall 12 extends between the upstream conduit chamber 36 and the downstream conduit chamber 38, thereby providing a fluid connection between the chambers.

An upstream sensor chamber 40 is defined in the body 2, for receiving an upsfream sensor port 22, described in more detail hereinafter. The upstream sensor chamber 40 is in fluid communication with the upsfream conduit chamber 36 by means of an upstream channel 26 extending transversely between the upstream sensor chamber 40 and the upstream conduit chamber 36.

A downsfream sensor chamber 42 is defined in the body 2, for receiving a downstream sensor port 24, described in more detail hereinafter. The downstream sensor chamber 42 is in fluid communication with the upsfream conduit chamber 36 at a point further downstream than the upstream sensor chamber 40, by means of a downstream channel 28 extending transversely between the downstream sensor chamber 42 and the upstream conduit chamber 36. The upstream and downstream sensor chambers 40, 42 have screw threads on their walls 44, 46 for engagement with corresponding screw threads on the outer walls of the sensor ports 22, 24, to allow the sensor ports to be secured within the chambers.

The body 2 has a port 48 towards its outlet 6, for receiving a spindle arrangement, designated generally by reference 18, of the valve mechanism 10, described in more detail hereinafter. The port 48 has a screw thread on its internal surface 50 for engagement with a corresponding screw thread on the spindle arrangement 18, to thereby fasten the spindle arrangement to the body 2.

The upstream conduit chamber 36, upsfream of the wall 12, generally comprises a substantially smooth cylindrical bore extending from the inlet port 4 towards the wall 12. A recess 52 extending circumferentially around the inner surface of the body 2 is provided downstream of the downstream channel 28. The recess 52 is sized so as to partially receive a locking ring 84 of the flow venturi 30, described in more detail hereinafter. However, as will be appreciated, the height of the recess 52 is no larger than the cross-sectional diameter of the locking ring 84. Therefore, the locking ring 84 will not be fully received within the recess 52, when the locking ring and recess are co- located. The diameter of the upstream conduit chamber 36, downstream of the recess 52, is sized to be smaller than the diameter of the upsfream conduit chamber 36, upstream of the recess 52.

The valve mechanism 10 of the valve assembly has a plug 16 that is shaped and sized to be received by the aperture 14. The plug 16 is mounted upon the spindle arrangement 18, which in turn is mounted on the port 48 via means of a cooperating screw thread, so that the plug 16 of the valve mechanism 10 is co-axial with the aperture 14, and located on the side of the aperture proximal to the outlet port 6. When mounted, the spindle arrangement 18 provides translational movement of the plug in a direction co-axial with the aperture 14, both towards and away from the aperture, upon operation of the spindle arrangement. The spindle arrangement is operated by rotation of a handle 20 that is co- axially mounted on the spindle arrangement 18. The configuration and operation of spindle arrangements for adjusting the translational position of a plug in valve assemblies will be understood by a person of ordinary skill in the art, and therefore are not described in any further detail herein. A suitable valve and spindle arrangement is the STAD model available from Tour & Anderson AB of Ljung, Sweden.

The upstream sensor port 22 is mounted on the body 2 within the upstream sensor chamber 40. The upstream sensor port 22 can be any conventional sensor port for receiving a pressure or temperature measuring instrument. The upstream sensor port has an elongate body 94 having a screw thread at a first end for engagement with the screw thread on the wall 44 of the upstream sensor chamber 40. The upstream sensor port further has a stop ring 96 towards its first end, a sealing body 98, a holding element 100, a seal 102, a cover 104, a neck opening 106, and an insertion opening 108. The neck opening 106 and insertion opening 108 are designed for insertion of a pressure or temperature measuring instrument. A suitable sensor port is the standard sensor model included in a number of products, such as the STAD model, provided by Tour & Andersson AB of Ljung, Sweden. The configuration and operation of sensor ports for receiving measuring instruments are well known, and are therefore not described in any further detail herein.

The downstream sensor port 24 is mounted on the body 2 within the downstream sensor chamber 44. The downstream sensor port 24 can be any conventional sensor port for receiving a pressure or temperature measuring instrument. The downstream sensor port 24 is identical in configuration to the upstream sensor port 22, and the parts of the downstream sensor port indicated by reference numerals 110 to 124, correspond to the parts of the upstream sensor port indicated by reference numerals 94 to 108.

The flow venturi, best shown in figure 2, generally comprises an inlet portion 54, a throat portion 56 that is downsfream of the inlet portion 54 when the flow venturi 30 is inserted into the body 2, and a tapered outlet portion 58 that is downstream of the throat portion 56.

The inlet portion 54 has a tubular part, having an outer diameter similar to that of the upsfream conduit chamber 36, upsfream of the recess 52, so the inlet portion is a snug fit within the upstream conduit chamber 36 when inserted therein. The tubular part has a first upstream recess 60 extending annularly around the outer surface of the tubular part, for receiving an O-ring 62. The O-ring 62 provides a tight seal between the inlet portion 54 and the inner surface of body 2 when inserted therein. The tubular part further comprises a second recess 64, downstream of the first recess 60, also extending annularly around the exterior surface of the inlet part 54. Four channels 66 extend transversely between the inner surface of the tubular part of the inlet portion 54 and the second recess 64 for providing a fluid connection there between. The four channels 66 are spaced equi- angularly around the tubular part, relative to each other, i.e. 90E apart in the described embodiment.

The throat portion 56 of the flow venturi 30 comprises a tubular part having an outer diameter that is substantially smaller than inner diameter of the upstream conduit chamber 36, upstream of the recess, so that a gap between them exists when the flow venturi is inserted therein. The tubular part of the throat portion 56 has an annularly extending wall 68 at its upstream end, the wall 68 having an outer diameter similar to that of the diameter of the upsfream conduit chamber 36 so that it is a snug fit when the flow venturi is inserted therein. The wall 68 has a recess extending annularly around its circumference for receiving an O-ring 72. The O-ring 72 provides a tight seal between the wall 68 and the inner surface of the body 2 when the flow venturi is inserted therein. The tubular part of the throat portion 56 further comprises four channels 74 extending transversely between the inner and outer surfaces of the tubular part 56, downstream of the wall 68. The four channels 74 are equi-angularly positioned around the tubular part, relative to each other.

The tapered outlet portion 58 of the flow conduit 30 comprises a tubular part having an outer diameter slightly smaller than the diameter of the upstream conduit chamber 36, so that a gap between them exists when the flow venturi is inserted therein. The outer diameter of the tubular part of the outlet portion 58 is bigger than the outer diameter of the tubular part of the throat portion 60. The interior diameter of the tapered outlet portion 58 increases uniformly as you travel from the upstream most part of the outlet portion 58 to its downstream most part. The internal diameter of the tapered outlet portion 58 at its upstream most end is the same size as the internal diameter of the throat portion 56. First 76, second 78 and third 80 axially spaced walls that extend annularly around the outer surface of the tapered outlet portion 58 are provided its downsfream most end. The first 76 and second 78 walls define a first recess 82 in which a locking ring 84 is retained. The height of the first recess 82 in the flow venturi will be no smaller than the cross-sectional diameter of the locking ring 84 in which it is located, so that the locking ring can be wholly received within the recess. The second 78 and third 80 walls define a second recess 86 in which an O-ring 88 is retained. The O-ring 88 provides a tight seal between the tapered outlet portion 58 and the inner surface of the body 2 when the flow venturi is inserted therein.

The locking ring 84, is a split "C" ring that is flexible so that it is capable of being compressed. In this embodiment, when the locking ring 84 is compressed, the ends of the ring are abutting. However, it will be appreciated that the ends of the locking ring 84 do not need to be abutting when the locking ring is in its compressed state. The locking ring 84 is sufficiently resilient so that upon removal of the compressive force, the locking ring expands outwardly, towards its original shape, so that its ends no longer abut. The outer diameter of the locking ring 84, when in its compressed state, is no bigger than the diameter of the upstream conduit chamber 36, upsfream of the recess 52 defined in the inner surface of the body 2. The outer diameter of the locking ring 84, when in its expanded, uncompressed state, is no smaller than the diameter of the recess 52.

In use, the flow venturi 30 is slidingly inserted into the body 2 through the inlet 4, with the tapered outlet portion 58 of the flow venturi entering the body first. As the flow venturi 30 is slid along the upstream conduit chamber 36 towards its desired location, the locking ring 84 is compressed by the inner surface of the body 2 so that its ends are abutting. Therefore, as the flow venturi 30 is slid along the upstream conduit chamber 36, the locking ring 84 will be biassed outwardly from the flow venturi to engage against the inner surface of the body 2. Therefore, as the locking ring 84 passes the upsfream and downstream channels 26, 28, any burrs present around the openings of the upstream and downstream channels will be removed by the scraping action of the locking ring 84 against such burrs. This can be advantageous because the removal of the burrs will help prevent damage to the O-rings further upsfream of the locking ring 84, which can be cut by the sharp edges of the burrs.

The flow venturi is slid along the upstream conduit chamber 36 until it reaches a site at which the locking ring 84 and the recess 52 defined in the inner surface of the body 2 are co-located, at which point the locking ring 84 will be free to expand into the recess 52. When the flow venturi 30 is located within the body 2 as such, it is said to be at its site. The expansion of the locking ring 84 into the recess 52 will therefore prevent the flow venturi from being slid back towards the inlet port. Further, the provision of the first wall 76 of the tapered outlet portion 58, which has a diameter greater than the diameter of upstream conduit chamber 36, downsfream of the recess 52, prevents movement of the flow venturi further downstream of the upsfream conduit chamber 36. The provision of the first 76 and second 78 walls that have diameters similar to that of the inner surface of the body 2 upstream of the recess 52, prevents access to the locking ring 84. Therefore, it is not possible for a compressive force to be applied to the locking ring once it has been located in the recess 52 defined in inner surface of the body 2, and therefore the venturi cannot be removed.

Once the flow venturi has been inserted at its site in the body 2, the recess 64 on the inlet portion 54 of the flow venturi 30 is in fluid communication with the upstream channel 26, and therefore the recess 64 provides a fluid connection between the upstream sensor chamber 40 and the inlet channels 66. Further, a space 92 is defined between the inner surface of the body 2 and the outer surfaces of the throat portion 56 and tapered outlet portion 58. This space 92 is in fluid communication with the downstream channel 28 and also with the four throat channels 74. Therefore, space 92 co-operates with throat channels 74 to provide a fluid connection between the downsfream sensor chamber 42 and the fluid at the throat portion 56. In alternate embodiments, space 92 need not be provided and channels 74 can be configured to communicate directly with the downsfream channel 28. Leakage of fluid between the communication channels 90, 92 and the upstream conduit chamber 36 around the outer circumference of the flow venturi is prevented by the O-rings 62, 72 and 88 of the inlet portion 54, the throat portion 56, and the tapered outlet portion 58, which form a tight seal with the inner surface of the body 2.

Once the flow conduit has been inserted into the valve assembly, the valve assembly can be employed in a fluid system for measuring and controlling the flow of fluid through the valve assembly. Fluid enters the valve assembly through the inlet port 4, flows through the flow venturi 30 located in the upsfream conduit chamber 36, then through the aperture 14 into the downsfream conduit chamber 36 and then out of the valve assembly through the outlet port 6. The pressure of fluid at the inlet portion 54 of the flow venturi can be measured by insertion of a pressure sensor into upstream sensor port 22 which is in fluid communication with the four channels 66 in the inlet portion 54. The pressure of fluid at the throat portion 56 of the flow conduit 30 can also be measured using a pressure sensor inserted into the downsfream sensor port 34 which is in fluid communication with the four channels 74 of the throat portion. Any standard measuring instrument for measuring the pressure or temperature of fluid in the chamber in which the sensor port the measuring instrument is inserted can be used. A suitable measuring instrument is the TA-CBI model from Tour & Anderson AB of Ljung, Sweden.

The difference between the pressure readings can be used to calculate the rate of flow of fluid through the valve assembly. Therefore, if the rate of flow of fluid is too great the valve can be closed in the manner described hereinafter to reduce the rate of flow of fluid. Conversely, if the flow of fluid is too small the valve assembly can be opened to decrease the resistance to flow and therefore increase the flow of fluid through the valve assembly.

Claims

CLAIMS:

1. A valve assembly for controlling the flow of fluid therethrough, the valve assembly comprising: a body having: an inlet and an outlet at opposed ends of the body; a conduit extending between the inlet and the outlet; an upsfream channel and a downstream channel providing fluid communication between the conduit and respective first and second chambers for respective first and second sensor ports; a valve, operable to control the flow of fluid through the conduit; and a flow venturi, insertable into a site in the body, the flow venturi having a throat portion, and wherein when the flow venturi is positioned at the site, the upstream channel provides fluid communication with fluid upsfream of the throat portion, and the downsfream channel provides a fluid communication with fluid at, or downsfream of, the throat portion, and wherein the flow venturi and a part of the body between them provide a latch mechanism actuable to lock the flow venturi in the body at the site and wherein the latch mechanism is inaccessible with the flow venturi at the site, thereby preventing the venturi from being removed from the body.

2. A valve assembly as claimed in claim 1 , in which the latch mechanism comprises a latch, and a recess for receiving the latch.

3. A valve assembly as claimed in claim 2, in which latch is biassed towards the recess, so that the latch is received within the recess when the flow venturi is positioned at the site.

4. A valve assembly as claimed in claim 2, in which the flow venturi includes the latch, the latch being biassed outwardly from an outer surface of the venturi to engage against an inner surface of the body as the flow venturi is inserted in the conduit toward the site.

5. A valve assembly as claimed in claim 4, in which the latch is located towards the downstream end of the flow venturi.

6. A valve assembly as claimed in claim 2, in which the latch extends substantially circumferentially around the outer surface of the flow venturi, and in which the recess is in the form of a groove which extends circumferentially around an inner surface of the body.

7. A valve assembly as claimed in claim 2, in which the latch comprises a locking ring.

8. A valve assembly as claimed in claim 2, in which the latch comprises a resiliently compressible split ring.

9. A valve assembly as claimed in claim 4, in which the latch is downstream of the downstream channel.

10. A valve assembly as claimed in claim 1, in which the flow venturi has an inlet portion upstream of the throat portion, the inlet portion having a plurality of channels providing communication between fluid at the inlet portion and the upstream channel, and in which the flow venturi has a plurality of channels providing communication between fluid downsfream of the inlet portion and the downsfream channel.

11. A valve assembly as claimed in claim 10, in which the flow venturi and body between them define a first slot providing fluid communication between the plurality of channels of the inlet portion and the upsfream channel.

12. A valve assembly as claimed in claim 10, in which the flow venturi and body between them define a second slot providing fluid communication between the plurality of channels downstream of the inlet portion and the downstream channel.

13. A valve assembly as claimed in claim 10, in which the first slot is an annular slot extending around the circumference of the inlet portion.

14. A valve assembly as claimed in claim 12, in which the second slot is an annular slot extending around the extending around the circumference of the flow venturi.

15. A valve assembly as claimed in claim 9, in which the plurality of channels of the inlet portion are spaced equi-angularly relative to each other around the inlet portion.

16. A valve assembly as claimed in claim 9, in which the plurality of channels of the throat portion are spaced equi-angularly relative to each other around the flow venturi.

17. A valve assembly for controlling the flow of fluid therethrough, the valve assembly comprising: a body having: an inlet and an outlet at opposed ends of the body; a conduit extending between the inlet and outlet; and an upstream channel and a downsfream channel providing fluid communication between the conduit and respective first and second chambers for respective first and second sensor ports; a valve, operable to control the flow of fluid along the conduit; and a flow venturi, locatable at a site in the body, the flow venturi having: an inlet portion; a throat portion downstream of the inlet portion; a plurality of channels providing communication between fluid at the inlet portion and the upsfream channel; and a plurality of channels proyiding communication between fluid downstream of the inlet portion and the downstream channel, when the flow venturi is positioned at the site.

18. A valve assembly as claimed in claim 17, in which the flow venturi and body between them define a first slot providing fluid communication between the plurality of channels of the inlet portion and the upsfream channel.

19. A valve assembly as claimed in claim 16, in which the flow venturi and body between them define a second slot providing fluid communication between the plurality of channels downstream of the inlet portion and the downsfream channel.

20. A valve assembly as claimed in claim 18, in which the first slot is an annular slot extending around the circumference of the inlet portion.

21. A valve assembly as claimed in claim 19, in which the second slot is an annular slot extending around the circumference of the flow venturi.

22. A valve assembly as claimed in claim 17, in which the plurality of channels of the inlet portion are spaced equi-angularly relative to each other around the inlet portion.

23. A valve assembly as claimed in claim 17, in which the plurality of channels downstream of the inlet portion are spaced equi-angularly relative to each other around the flow venturi.

24. A valve assembly as claimed in claim 17, in which there are at least four channels providing communication between fluid at the inlet portion and the upstream channel.

25. A valve assembly as claimed in claim 17, in which there are at least four channels providing communication between fluid downstream of the flow portion and the downstream channel.

26. A valve assembly as claimed in claim 17, in which the flow venturi is insertable into the site in the conduit, wherein the flow venturi and a part of the body provide between them a latch mechanism actuable to lock the flow venturi in the body when positioned at the site and wherein the latch is inaccessible with the venturi at the site, thereby preventing the venturi from being removed form the body.

27. A valve assembly as claimed in claim 26, in which the latch mechanism comprises a latch and a recess for receiving the latch.

28. A valve assembly as claimed in claim 27, in which latch is biassed towards the recess, so that the latch is received within the recess when the flow venturi is positioned at the site.

29. A valve assembly as claimed in claim 27, in which the flow venturi includes the latch, the latch being biassed outwardly from an outer surface of the venturi to engage with an inner surface of the body as the flow venturi is inserted in the bore toward the site.

30. A valve assembly as claimed in any of claims 17 to 25, wherein the flow venturi is located in the body.

31. A valve assembly as claimed in claim 30, wherein the flow venturi is secured in the body.

32. A valve assembly as claimed in claim 31, wherein the flow venturi is a part of the body.

33. A valve assembly for controlling the flow of fluid therethrough substantially as hereinbefore described.