A butterfly valve assembly for an engine arrangement, the butterfly valve
assembly comprising:
a valve housing defining at least part of a conduit; and
a valve member disposed within the conduit and rotatable about an axis
between an open configuration, in which fluid flow is permitted through the conduit
across the valve member, and a closed configuration, in which the valve member seals
the conduit;
wherein the valve member is rotatable in a first direction from the open
10 configuration to the closed configuration; and
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wherein the valve member comprises:
a blocking surface which extends across the conduit, in the closed
configuration, to seal the conduit;
a secondary surface which generally opposes the blocking surface; and
a peripheral surface which extends between the blocking surface and
the secondary surface and defines a thickness of the valve member;
wherein a first end portion of the peripheral surface extends around the axis at
a first end of the valve member;
wherein a clearance is defined between the conduit and a vertex of the first end
20 portion closest to the conduit; and
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wherein the clearance is at a minimum, as the valve member pivots from the
open configuration to the closed configuration, when the valve member is in the closed
configuration.
2. The butterfly valve assembly according to claim 1, wherein the first end portion
of the peripheral surface is defined by at least first and second recesses.
3. The butterfly valve assembly according to claim 2, wherein the first and second
recesses are disposed across the axis from one another.
4. The butterfly valve assembly according to claims 2 or 3, wherein the first recess
extends to the blocking surface, and the second recess extends to the secondary
surface.
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5. The butterfly valve assembly according to claim 4, wherein a mid-plane of the
valve member is defined through the peripheral surface between the blocking and
secondary surfaces; and
wherein the first recess extends at least from the blocking surface to the mid-
5 plane; and
wherein the second recess extends at least from the secondary surface to the
mid-plane.
6. The butterfly valve assembly according to claim 5, wherein the first recess
10 extends at least from the blocking surface past the mid-plane; and
wherein the second recess extends at least from the secondary surface past
the mid-plane.
7. The butterfly valve assembly according to any one of claims 2 to 6, wherein the
15 first end portion is further defined by third and fourth recesses.
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8. The butterfly valve assembly according to claim 7, wherein the first and third
recesses are disposed on one side of the first end portion, and wherein the second and
fourth recesses are disposed on the other side of the first end portion.
9. The butterfly valve assembly according to any preceding claim, wherein a bore
extends through the valve member along the axis.
10. The butterfly valve assembly according to claim 9, wherein the bore is disposed
25 in a thickened portion of the valve member.
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11. The butterfly valve assembly according to claims 9 or 10, wherein a lip of the
first end portion extends around the bore.
12. The butterfly valve assembly according to claim 11, wherein the first end portion
is further defined by first and second projections which extend from the lip.
13. The butterfly valve assembly according to claim 12, wherein the first and
second projections, and the lip portion, define a web of material, the web of material
35 defining the first end portion.
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14. The butterfly valve assembly according to claims 12 or 13, when indirectly
dependent upon claim 5, wherein the first projection is disposed on a first side of the
first end portion, and the second projection is disposed on the other side of the first end
5 portion.
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15. The butterfly valve assembly according to any one of claims 12 to 14, when
indirectly dependent upon claim 7, wherein the first projection is defined by the first and
third recesses, and the second projection is defined by the second and fourth recesses.
16. The butterfly valve assembly according to any preceding claim, wherein a
second end portion of the peripheral surface, corresponding to the first end portion, is
disposed at an opposing second end of the valve member.
17. The butterfly valve assembly according to any preceding claim, wherein the
clearance is at least around 0.3 mm when the valve member is at an 80% closed
position.
18. The butterfly valve assembly according to claim 5, or any one of claims 6 to 17
20 when directly or indirectly dependent upon claim 5, wherein the mid-plane and a
second plane, normal to the mid-plane and the axis, define four quadrants of the valve
member.
19. The butterfly valve assembly according to claim 18, wherein any projecting
25 feature(s) of the first end portion is located outside of two diagonally opposed
quadrants which are proximate the conduit when the valve member is in the closed
configuration.
20. The butterfly valve assembly according to claims 18 or 19, wherein the vertex is
30 located in one of two diagonally opposed quadrants which are distal the conduit when
the valve member is in the closed configuration.
21. The butterfly valve assembly according to any preceding claim, wherein the
butterfly valve assembly is an exhaust throttle valve (ETV) or exhaust gas recirculation