Butterfly valve

Claim 2

A butterfly valve comprising a housing in which a flat flap having an elastic rim is adapted to turn between a position in which the plane of the flap is parallel to the axis of the flow passage across the housing and a position in which the elastic rim is in sealing relationship to a seat arranged all around the axis of the passage across the housing, said seat having the shape of a cone surface, the apex of the cone being located outside the axis of the flow passage across the housing, characterised in that the sealing surface of the seat lies on the peripheral surface of the base of an oblique circular cone, the circular base of said cone being at right angles to the axis of the flow passage of the seat.

Claim 3

A butterfly valve as claimed in claim 1, characterised in that the flap has a circular shape, the diameter thereof being equal to the diameter of the mean circular section of the seat plus an excess measure.

Claim 4

A butterfly valve as claimed in claim 1 characterised in that the apex of the cone is located on a perpendicular line at a point of the circumferential rim to the base plane of the cone.

Claim 5

A butterfly valve as claimed in claim 1 characterised in that the axis of rotation of the flap is at right angles to the plane going through the apex of the cone and the axis of the passage across the housing.

Claim 6

A butterfly valve as claimed in claim 2 characterised in that the apex of the cone is located on a perpendicular line at a point of the circumferential rim to the base plane of the cone.

Claim 7

A butterfly valve as claimed in claim 2 characterised in that the axis of rotation of the flap is at right angles to the plane going through the apex of the cone and the axis of the passage across the housing.

Claim 8

A butterfly valve as claimed in claim 3 characterised in that the axis of rotation of the flap is at right angles to the plane going through the apex of the cone and the axis of the passage across the housing.

Claim 9

A gate valve construction comprising, in combination: a valve housing having a band-like seating surface defining an axial passage for conducting fluid, said seating surface being of decreasing circular section at planes normal to the axis of said passage from one side of the seating surface to the other side thereof, whereby said seating surface lies on the peripheral surface of the base of a right circular cone having its apex offset from said axis; a generally circular, plate-like valve member having an elastic rim adapted to seat circumferentially along a closed path against said seating surface; and pivotal mounting means connecting said valve member to said housing for defining a pivotal axis offset from the plane of said valve member and from the geometrical center thereof by respective amounts sufficient to permit said valve member to move between a seated position and an open position parallel to said axis of the passage defined by said seating surface.

Claim 10

A gate valve construction comprising, in combination: a valve housing having a band-like seating surface defining an axial passage for conducting fluid, said seating surface being of decreasing circular section at planes normal to the axis of said passage from one side of the seating surface to the other side thereof, whereby said seating surface lies on the peripheral surface of the base of a right circular cone having its apex offset from said axis; a generally circular, plate-like valve member having an elastic rim adapted to seat circumferentially along a closed path against said seating surface; and pivotal mounting means connecting said valve member to said housing for defining a pivotal axis offset from the plane of said valve member and from the geometrical center thereof by respective amounts sufficient to permit said valve member to move between a seated position and an open position parallel to said axis of the passage defined by said seating surface.

Claim 11

A gate valve as defined in claim 8 wherein said seating surface is parallel to said axis of the passage at one circumferential point on said seating surface.

Claim 12

A gate valve as defined in claim 9 wherein said valve member is circular and is of a diameter substantially equal to the mean diameter of said seating surface.

Claim 13

A gate valve as defined in claim 10 wherein said pivotal axis of the valve member is at right angles to a plane containing the apex of said oblique cone and said axis of the passage defined by said seating surface.

Claim 14

A gate valve as defined in claim 8 wherein said valve member is circular and is of a diameter substantially equal to the mean diameter of said seating surface.

Claim 15

A gate valve as defined in claim 12 wherein said pivotal axis of the valve member is at right angles to a plane containing the apex of said oblique cone and said axis of the passage defined by said seating surface.

Claim 16

A gate valve as defined in claim 8 wherein said pivotal axis of the valve member is at right angles to a plane containing the apex of said oblique cone and said axis of the passage defined by said seating surface.