GB2535751A

GB2535751A - Angled butterfly valve

Info

Publication number: GB2535751A
Application number: GB1503210.5A
Authority: GB
Inventors: Banister Peter
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2015-02-26
Filing date: 2015-02-26
Publication date: 2016-08-31
Also published as: GB201503210D0

Abstract

A butterfly valve includes a valve housing 12 defining a conduit 14 through which fluid can flow. A valve plate 16 is located in the conduit 14 and is rotatable between a closed position in which the valve plate prevents the flow of fluid through the conduit and an open position in which the valve plate permits the flow of fluid through the conduit. In the closed position, the valve plate 16 is tilted with respect to the conduit 14. This provides improved valve initial opening/closing response.

Description

ANGLED BUTTERFLY VALVE

Field of the Invention

The present invention relates to a butterfly valve having a movable valve plate for controlling the flow of a fluid through a conduit of the butterfly valve; in particular to a valve plate which is angled (tilted) with respect to the long axis of the conduit when in the closed position.

Background of the Invention

Conventional designs of butterfly valves, such as those used in air flow control for gas turbine case cooling, have an arrangement such that the valve plate in the fully closed position is perpendicular (normal) to the direction of fluid flow, and the valve plate is generally in line (parallel) with the flow through the valve in the fully open position. In the closed position the flow of fluid is prevented (prohibited), whereas in the fully open position the flow of fluid is permitted, and is typically at a maximum flow.

A generalized example is shown in Figure 1, which shows a prior art butterfly valve 1, including a valve body 3 defining a conduit 5 through which fluid is able to flow. A valve plate 7 is provided in the conduit 5. The valve plate 7 is tiltable (pivotable) about pivot 8.

The valve plate 7 is movable between an open position which permits the fluid to flow through the conduit 5, and a closed position which prevents the fluid flowing through the conduit 5. The conduit 5 has a long axis parallel to the general direction of flow of the fluid through the conduit. In the closed position, the valve plate 7 is arranged perpendicular to the long axis. The valve plate 7 is typically arranged parallel to the long axis when in a fully opened position.

The present inventors have appreciated that a disadvantage with the conventional designs of butterfly valves is that at least for the initial portion of valve opening, the increase in valve bore area provided for the fluid to flow through is relatively small for a relatively large amount of movement (tilt) of the valve plate.

Summary of the Invention

Accordingly, the present invention provides a butterfly valve as set forth in claim 1.

The present invention offers a benefit of an improved valve plate position (tilt angle) to valve area relationship, giving increased initial valve opening/closing response and improved valve area positioning accuracy characteristics, relative to valve actuation (i.e. relative to active tilting of the valve plate).

In the closed position the valve completely prevents (prohibits) the flow of fluid through the conduit.

The conduit has a long axis, parallel to the general direction of flow of fluid through the conduit. When in the closed position, the valve plate is arranged tilted (angled) relative to the long axis; as shown in Figure 2.

When in the closed position, the valve plate may be arranged tilted at 80 degrees or less relative to the long axis. In other words, the valve plate may be arranged tilted at 10 degrees or more from an axis which is perpendicular to the long axis.

When in the closed position, the valve plate is preferably arranged tilted at 65 degrees or less relative to the long axis. In other words, the valve plate may be arranged tilted at 25 degrees or more from an axis which is perpendicular to the long axis.

The conduit may have a circular cross-section, e.g. when viewed along the long axis of the conduit, and the valve plate may be formed (provided) as an oval, for example an ellipse; for example as shown in Figure 3. Where the conduit is of a circular cross-section an oval or elliptical shaped valve plate may allow the valve plate to seal in the closed position without the need for seals to protrude into the conduit. Such protruding seals would be necessary if the valve plate were circular in order for the valve plate to be capable of sealing the conduit in a tilted closed position. Protruding seals as described would however reduce the cross-sectional area of the conduit and increase flow back-pressure with the valve open. An eccentric valve plate may therefore be advantageous. The valve plate may be planar.

The conduit may include a lip formed at least partially around its internal surface, and when in the closed position the valve plate preferably cooperates with the lip to form a seal therewith.

The conduit may be formed to include a recess around at least a portion of the internal surface. The lip may at least partially define the recess. A perimeter region of the valve plate may be received in the recess when the valve plate is in the closed position.

In the closed position, the valve plate may abut the lip to form the seal.

The valve plate is preferably tiltable between the open and closed positions.

In an aspect, the present invention provides a gas turbine engine which may include a butterfly valve according to the present invention, as described in any aspect or embodiment herein.

The gas turbine engine may have a cooling assembly including the butterfly valve. The cooling assembly may be configured for cooling of the turbine case of the gas turbine engine.

The fluid may include one or more gases and/or one or more liquids.

The valve plate is preferably tiltable about a pivot point or axis. For example, the valve plate may be tiltable about a pivot.

The valve plate pivot point (or axis) may be chosen such that the valve plate pivots symmetrically thereabout, or it may be offset higher or lower to offer asymmetric bias to the dynamic loading on the valve plate in the open or close direction.

For example, the valve plate may be asymmetrically tiltable between the open and closed positions about the pivot axis. The pivot axis may be referred to as a tilting axis.

In particular, the valve plate preferably has an axis of symmetry about which it is tiltable. Preferably, the pivot axis is coaxial with this axis of symmetry. But, optionally, the pivot axis may be parallel with, but not coaxial with, this axis symmetry.

The tilt angle (relative to the long axis) is preferably measured between the portion of the valve plate which is downstream (relative to the direction of flow of the fluid) of the pivot point (or axis) and the portion of the long axis which is also downstream of the pivot point.

The pivot point may lie on the long axis. The pivot axis may intersect the long axis.

The pivot axis, the long axis and the aforementioned axis perpendicular to the long axis may be mutually orthogonal.

Brief Description of the Drawings

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a prior art arrangement of a butterfly valve; Figure 2 shows a butterfly valve according to an aspect of the present invention; Figure 3 shows a butterfly valve according to an aspect of the present invention; Figure 4 shows an idealised plot for the valve flow area percentage as a function of the valve plate angle relative to an axis perpendicular to the long axis of the conduit/bore, for the prior art butterfly valve shown in Figure 1 (it is idealised because the valve plate thickness is ignored); Figure 5 shows an idealised plot for the valve flow area percentage as a function of the valve plate angle relative to an axis perpendicular to the long axis of the conduit/bore, for butterfly valves according to the present invention ("closed at 25 deg", "closed at 45 deg"), in addition to the prior art butterfly valve shown in Figure 1 ("closed at 0 deg") (the plot is idealised because the valve plate thickness is ignored); Figure 6 shows an idealised plot for the rate of opening of a butterfly valve as a function of movement of the valve plate, and the associated error in the full scale positioning accuracy of the valve plate, for both (i) a butterfly valve according to the present invention (thick plot line) and (ii) the prior art butterfly valve of Figure 1 (thin plot line) (the plot is idealised because the valve plate thickness is ignored); Figure 7 shows an idealised plot of the area accuracy achievable at a specific valve area (point accuracy), as a function of the movement of the valve plate, for both (i) a butterfly according to the present invention (thick plot line) ("closed at 25 deg" example) and (ii) the prior art butterfly valve of Figure 1 (thin plot line) (the plot is idealised because the valve plate thickness ignored); and Figures 8 (A) and (B) show a butterfly valve according to another aspect of the present invention Detailed Description and Further Optional Features of the Invention A generalized embodiment according to an aspect of the present invention is shown in Figure 2, which shows a butterfly valve 10 including a valve body 12 defining a conduit or bore 14 through which fluid is able to flow. A valve plate 16 is provided in the conduit 14 for control of the flow of fluid through the valve. The valve plate 16 is tiltable (or pivotable) about pivot 18 to control the rate of flow of fluid through the valve.

The valve plate 16 is movable between an open position which permits the fluid to flow through the conduit 14 (i.e. through the valve 10), and a closed position which prevents (prohibits) the fluid flowing through the conduit 14 (i.e. through the valve 10).

The conduit 14 has a long axis parallel to the general direction of flow of the fluid through the conduit 14.

In the closed position, the valve plate 16 is arranged tilted with respect to the long axis. For example, when in the closed position the valve plate 16 is arranged within the conduit 14 so that the long axis is not normal to the valve plate, for example so that the long axis is at an angle to the valve plate other than the normal.

The valve plate 16 may be arranged tilted at 80 degrees or less relative to the long axis when in the closed position. Preferably, the valve plate 16 is arranged tilted at 65 degrees or less relative to the long axis when in the closed position.

For example, when in the closed position, the valve plate 16 is typically arranged at an acute angle with respect to a surface of the valve body 12 defining the conduit or bore 14.

The valve plate 7 is typically arranged parallel to the long axis when in a fully opened position.

The valve plate 7 is movable, e.g. tiltable, throughout a range of tilt angles between the open and closed positions to provide variable control over the flow of the fluid through the valve.

Where the conduit 14 is provided as a cylinder, e.g. with a cylindrical bore or lumen, the valve plate 16 may be provided as an oval, e.g. an ellipse. In this way, the valve plate 16 and the conduit 14 are able to cooperate to provide an effective seal when the valve plate 16 is in the closed position, thereby preventing fluid flow through the valve 10. A figurative example is shown in Figure 3.

Figure 4 shows characteristics of the prior art valve butterfly valve 1 shown in Figure 1.

In particular, Figure 4 shows the relationship between the percentage of the total valve flow area which is presented to the fluid for it to flow through, as a function of the valve plate angle for the butterfly valve of Figure 1. In essence, the valve flow area percentage represents the proportion of the maximum available aperture which is presentable by the valve to the fluid for it to flow through, ranging from a 0% area (i.e. the valve is fully closed) to a 100% area, where the maximum area is presented (i.e. the valve is fully open).

The valve plate angle represents the tilt angle of the valve plate 7 relative to an axis which is perpendicular to the long axis of the conduit or bore 5. This perpendicular axis is thus represented as 0 degrees on the x-axis, whereas the long axis itself is represented as 90 degrees.

As will be recalled from the discussion of Figure 1, in the prior art valve assembly, the valve plate 7 is arranged perpendicular to the long axis of the conduit or bore 5 when in the closed position. Furthermore, in the open position, the valve plate 7 is arranged parallel to the long axis. Therefore, the full tilt range of the prior art valve plate is 90. Hence, the plot in Figure 4 shows that the prior art valve plate 7 is tiltable through the entire 90 degrees between the axis perpendicular to the long axis, and the long axis itself.

As will be appreciated from Figure 4, this means that for the prior art valve assembly the first degrees of valve plate 7 opening (tilting) results in less than 10% of the total valve area being opened and presented for the flow of fluid therethrough.

This represents only a small increase in valve area (<10%) for a relatively large movement, or tilt, (28% = 25 degrees of a possible 90 degrees) of the valve plate. Naturally, it takes time and considerable input travel to move the valve plate from e.g. 0 degrees to 25 degrees (and beyond), and therefore the rate at which the flow can be increased by an appreciable amount is relatively slow in the prior art. This latency is undesirable.

Indeed, as is shown in Figure 4, tilting the prior art butterfly valve 1 by 10 degrees from the closed position (i.e. an --11% tilt) results only in providing 1.52% of the total possible flow area through the valve 1.

Figure 5 shows a plot equivalent to Figure 4 overlaid with additional plot lines corresponding to characteristics of two respective embodiments of the present invention.

The first of the two embodiments is a butterfly valve according to the present invention where the valve plate 16 is tilted at 25 degrees relative to the axis which is perpendicular to the long axis of the conduit 14 when it is in the closed position. In other words, when in the closed position, the valve plate 16 is tilted at 65 degrees relative to (and towards) the long axis. In Figure 5, the plot line for this embodiment is the middle plot line and is labelled "closed at 25 deg".

In the second of the two embodiments, the valve plate is tiled at 45 degrees relative to the aforementioned axis which is perpendicular to the long axis of the conduit 14 when it is in the closed position. Therefore, when in the closed position, the valve plate 16 is also tilted at 45 degrees relative to the long axis. In Figure 5, the plot line for this embodiment is the plot line on the right hand side and is labelled "closed at 45 deg".

For comparison, the plot line corresponding to that shown in Figure 4 is included in Figure 5 for the prior art valve shown in Figure 1 and is labelled "closed at 0 deg".

As can be seen, for each of the two embodiments a 10 degree tilt from the respective closed position results in a significantly larger percentage increase in the valve flow area compared with a 10 degree tilt of the prior art valve shown in Figure 1.

For example, for a 10 degree tilt from the closed position, the prior art valve provides only 1.52% of the total possible area for the fluid to flow through. Whereas, for a 10 degree tilt from the closed position, the first embodiment (closed at 25 deg) provides 9.62% of the total valve area for the fluid to flow through. The second embodiment provides an even larger percentage of the total valve area for the fluid to flow through in response to a 10 degree tilt from the closed position.

The relative tilt of the valve plate 16 may be controlled on the basis of a percentage of the full tilt range. Therefore, it is also useful to look at the difference between the valve flow area provided by a butterfly valve according to the present invention and according to the prior art valve shown in Figure 1.

Tilting, from the closed position, the valve plate 5 of the prior art valve by 10% of the full tilt range provides only 1.23% of the total valve flow area for the fluid to flow through. Whereas, tilting, from the closed position, the valve plate 16 of a butterfly valve 10 according to the first embodiment by 10% of the full tilt range provides around 5.92% of the total valve flow area for the fluid to flow through. Therefore, a valve according to the present invention is able to be opened/closed to a greater extent more rapidly, for example.

Accordingly, an aspect of the present invention provides a butterfly valve for which the initial rate of increase/decrease in valve flow area relative to the movement range of the valve plate 16 is improved with respect to the prior art valve.

Furthermore, as is demonstrated by Figure 5 for example, a butterfly valve according to the present invention also provides a more linear relationship between the valve flow area and the movement, or tilt, of the valve plate 16 than the prior art valve.

Indeed, position accuracy relative to valve plate movement, or tilt, is also improved in a butterfly valve according to the present invention relative to the prior art valve.

Depending on the particular application, the tilt angle of the valve plate 16 in the closed position can be chosen accordingly to provide the desired response. This provides a means to select suitably the desirable rate of flow area response, valve area positioning accuracy and linearity between the valve angle and flow area relationship.

Figure 6 shows a plot lines which characterize for an embodiment of the present invention (thick plot line) and for the prior art valve of Figure 1 (thin plot line) the rate at which the valve flow area can be opened. Figure 6 represents an embodiment of the present invention in which the valve plate is arranged tilted with respect to a perpendicular to the long axis of the bore by 25 degrees when in the closed position (i.e. the valve plate is arranged tilted with respect to the long axis by 65 degrees when in the closed position). Each plot line in Figure 6 is plotted as a function of the relative position (i.e. relative tilt angle) of the valve plate between the closed position (0%) and the open position (100%). In other words, this plot shows the percentage of the total available valve flow area which is presented for the fluid to flow through it as a function of the relative position (i.e. the relative tilt angle) between the closed position (0%) and open position (100%) of the valve plate.

As will be seen from Figure 6, the initial rate at which the valve flow area of the valve can be opened/closed in a valve according to the present invention is significantly greater than that

of the prior art valve shown in Figure 1.

Figure 6 also demonstrates the present invention provides improved full scale valve area positioning accuracy at larger angles relative to valve actuation (i.e. relative to active tilting of the valve plate). For example, the valve area variation as a percentage of the full scale area at larger angles is reduced relative to the valve plate position range. It should be noted that at all (tilt) positions the valve area variation as a percentage of the area of that point is reduced relative to the valve plate position range. That is, the area accuracy achievable for a specific valve area (point accuracy) is improved.

This can be seen with reference to Figure 7, which plots the valve area percentage error based on the specific valve area (area at that point) due to an input error of 1% against the valve opening percentage (0% being fully closed, 100% being fully open).

In embodiments, the surface defining the bore 14 through which the fluid is able to flow may be smooth, e.g. with no recesses or projections formed therein or thereon. When in the closed position, the valve plate 16 may therefore abut against the smooth surface to form a seal therewith suitable for preventing flow of fluid through the valve.

However, in other embodiments, the surface may be shaped to include a recess, formed at least partially around the long axis of the bore. An example of a suitable configuration is shown in Figure 8, where Figure 8(A) shows a side cross-section of the configuration and Figure 8(B) shows a close up view of the region in which the valve plate 16 and the recess 20 formed in the surface cooperate to form a seal.

When in the closed position, a rim or perimeter region 21 of the valve plate 16 is received in the recess 20. The recess is therefore correspondingly shaped to receive the perimeter region 21. Thus, where the valve plate 16 is oval, e.g. elliptical, then the recess is preferably formed in the surface to be correspondingly oval, e.g. elliptical, to receive the perimeter region 21 when the valve plate is in the closed position.

When the valve plate is in the closed position, the recess and perimeter region 21 cooperate to form a suitable seal to prevent the flow of fluid through the valve 10.

The recess may be at least partially defined by a lip portion 22. The perimeter region may abut against the lip portion 22, for example to form the seal. The lip portion 22 and/or the perimeter region 21 may be provided with a sealing element to assist in forming and maintain a suitable seal. For example, the sealing element(s) may be a suitably shaped rubber body for example.

Instead of providing a recess formed in the surface, a ridge projecting from the surface may be provided. The valve plate 16 may abut against the ridge to form the seal when in the closed position.

However, a recess is preferred over a ridge, because the recess does not reduce the overall available valve flow area relative to e.g. the prior art, whereas a ridge would have the effect of the reducing the overall available valve bore flow area relative to the prior art.

Accordingly, aspects of the present invention provide: increased valve area opening/closing response relative to valve plate tilt angle (between fully open and closed positions), particularly during the initial stages of valve opening and final stages of valve closing; improvement in flow area positioning accuracy due to reduction in relative valve actuation range and improved geometric relationship of the valve plate position to bore area; improved control gain in the valve flow area to valve plate position (tilt angle) relationship (between fully open and closed positions).

a more linear valve flow area response to valve plate tilt angle (between fully open and closed positions); faster response due to reduced valve angle range and the relative actuation travel of e.g. an actuator arranged to adjust the tilt angle of the valve plate.

The present invention can be applied to any suitable cross-sectional shape of bore (conduit), for example circular, square, rectangular, elliptical, triangular or other profiles appropriate to the installation arrangements of the valve.

The valve plate is not restricted to being a broadly flat surface and can take on alternative profiles that will provide alternative flow characteristics.

The valve plate pivot is not restricted to being symmetrically placed on (arranged with respect to) the valve plate and may be offset higher or lower to offer asymmetric bias to the dynamic loading of the valve plate.

The perimeter region of the valve plate can take on profiles that provide adequate mating (cooperation) with the surface defining the bore, e.g. the surface of the conduit, when closed.

The perimeter region is not restricted to the profiles shown in the appended figures, which are provided by way of example only.

The invention is equally applicable to the control of flow of one or more fluids, such as one or more gases and/or one or more liquids, including but not limited to fuels, oil, air etc. Advantageously, the invention can be applied to any technical field requiring a valve response with improved flow area to valve control gain, opening/closing response, improved accuracy and with more a linear valve response.

A list of reference numerals used in the present application to describe aspects and embodiments of the present invention is now provided: butterfly valve 10; valve body 12; conduit or bore 14; valve plate 16; pivot 18; recess 20; valve plate rim 21; lip portion 22.

Claims

CLAIMS1. A butterfly valve including: a valve housing (12) providing a conduit (14) through which fluid is able to flow; and a valve plate (16) located in the conduit (14), adjustable between a closed position in which the valve plate prevents the flow of fluid through the conduit and an open position in which the valve plate permits the flow of fluid through the conduit (14); wherein when in the closed position, the valve plate (16) is arranged tilted within, and with respect to, the conduit (14).
2. A butterfly valve according to claim 1, wherein the conduit (14) has a long axis parallel to the general direction of flow of fluid through the conduit (14).
3. A butterfly valve according to claim 2, wherein when in the closed position, the valve plate (16) is arranged tilted relative to the long axis.
4. A butterfly valve according to claim 2, wherein when in the closed position, the valve plate (16) is arranged tilted at 80 degrees or less relative to the long axis.
5. A butterfly valve according to claim 2, wherein when in the closed position, the valve plate (16) is arranged tilted at 65 degrees or less relative to the long axis.
6. A butterfly valve according to any one of the preceding claims, wherein the conduit (14) has a circular cross-section, and the valve plate (16) is formed to be an oval.
A butterfly valve according to claim 6, wherein the valve plate (16) is an ellipse.
8. A butterfly valve according to any one of the preceding claims, wherein the conduit (14) includes a lip formed at least partially around its internal surface, and wherein in the closed position the valve plate (16) cooperates with the lip to form a seal therewith.
9. A butterfly valve according to claim 8 the conduit is formed to include a recess (20) around at least a portion of the internal surface, wherein the lip at least partially defines the recess.
10. A butterfly valve according to claim 8 or 9 wherein in the closed position, the valve plate (16) abuts the lip to form the seal.
11. A butterfly valve according to any one of the preceding claims wherein the valve plate (16) is tiltable about a tilting axis between the open and closed positions.
12. A butterfly valve according to claim 11, wherein the valve plate (16) is asymmetrically tiltable between the open and closed positions.
13. A butterfly valve according to claim 11 or 12, wherein the valve plate (16) has an axis of symmetry about which it is tiltable, wherein the axis of symmetry is parallel to but not coaxial with the tilting axis.
14. A butterfly valve according to claim 11, wherein the valve plate (16) has an axis of symmetry about which it is tiltable, wherein the axis of symmetry is parallel to and coaxial with the tilting axis.
15. A gas turbine engine including a butterfly valve (10) according to any one of the preceding claims.
16. A gas turbine engine having a cooling assembly including a butterfly valve (10) according to any one of the preceding claims.