Patent EP-3133250-A1 (EP)
Inventor: WEBSTER JOHN
IPC: F02C7/28
Filed: 2016-07-29
Abstract: A sealing arrangement (30) for providing sealing between a first structure (10), e.g. a rotor shaft, and a second structure (15), e.g. a portion of a casing, of an engine, and between first (HP) and second (LP) pressure regions located between the first (10) and second (15) structures, the first pressure region (HP) being at a relatively higher pressure than the second pressure region (LP), and the first structure (10) being moveable relative to the second structure (15) along an axis, wherein the sealing arrangement (30) comprises: a sealing member (20), e.g. a sealing fin or disc, carried on the first structure (10) and extending towards the second structure (15), and having opposite first and second sides; and a rigid frame (40) mounted on the second structure (15) so as to be translatable relative thereto in a direction (S) substantially parallel to the said axis, the frame (40) comprising: a first seal portion (42) having opposite exterior and interior sides and a first seal face (60) on the interior side thereof, at least a portion of the first seal face (60) being in communication with the first pressure region (HP), and a second seal portion (44) spaced from the first seal portion (42) and having opposite exterior and interior sides and a second seal face (70) on the interior side thereof, at least a portion of the second seal face (70) being in communication with the second pressure region (LP), the first and second seal faces (60, 70) being spaced apart from one another with the first seal face (60) located to the first side of the sealing member (20) and the second seal face (70) located to the second side of the sealing member (20), and the frame (40) being configured and arranged, e.g. by use of a secondary seal device (90), such that the exterior sides of the first and second seal portions (42, 44) of the frame (40) are substantially pressure-balanced relative to each other; wherein: the first seal face (60) of the first seal portion (42) of the frame (40) and the first side of the sealing member (20) are configured to form a first pressure reduction zone (64), and the second seal face (70) of the second seal portion (44) of the frame (40) and the second side of the sealing member (20) are configured to form a second pressure reduction zone (74), and at least a portion of the first pressure reduction zone (64) is located relatively distal, in a direction substantially normal to the said axis, from the first structure (10) and at least a portion of the second pressure reduction zone (74) is located relatively proximal, in a direction substantially normal to the said axis, to the first structure (10), whereby the frame (40) is translatable relative to the second structure (15) in the said direction (S) substantially parallel to the said axis in response to relative movement of the first structure (10) along the said axis. 
     The relative radial positioning of the first and second pressure reduction zones gives rise to an automatic self-centring seal mechanism. The first and second pressure reduction zones may be designed with various shapes and configurations.