Piston seal ring
A split ring seal has: a first circumferential end and a second circumferential end; an inner diameter surface and an outer diameter surface; a first axial end face and a second axial end face. The outer diameter surface has a sealing surface. The first axial end face has: a first section; a second section outboard of the first section; and an axial protrusion between the first section and the second section The second axial end face has: a first sealing surface; a second sealing surface radially outboard of the first sealing surface; a circumferential channel between the first surface and the second sealing surface; and a plurality of channels extending radially outward from the circumferential channel.
1 . A split ring seal comprising:
a first circumferential end and a second circumferential end;
an inner diameter surface and an outer diameter surface, the outer diameter surface having a sealing surface; and
a first axial end face and a second axial end face, wherein:
the seal comprises a metallic substrate and a coating;
the first axial end face has:
a first section;
a second section outboard of the first section; and
an axial protrusion between the first section and the second section; and
the second axial end face has:
a first surface;
a second surface radially outboard of the first surface;
a circumferential channel between the first surface and the second surface; and
a plurality of channels extending radially outward from the circumferential channel to an outboard radial extreme of the outer diameter surface.
2 . The split ring seal of claim 1 wherein:
the plurality of channels segment an outboard section of the first face that extends from the circumferential channel to the outer diameter surface.
3 . The split ring seal of claim 1 wherein:
the plurality of channels is 5 to 50 channels.
4 . The split ring seal of claim 1 wherein:
the circumferential channel and the plurality of channels have depth (D 1 ) of 15% to 30% of a length (L C1 ) of the outer diameter surface, and wherein the outer diameter surface is cylindrical.
5 . The split ring seal of claim 1 wherein:
a seal outer diameter radius (R O ) is between 10 cm and 40 cm; and
a seal radial span (H O ) is between 1.0 mm and 12 mm.
6 . The split ring seal of claim 5 wherein:
a seal radial span (H O ) is between 2% and 10% of the seal; outer diameter radius; and
said seal radial span is between 130% and 200% of a seal axial span (L O ).
7 . The split ring seal of claim 1 wherein:
the axial protrusion is radially recessed from the outer diameter surface sealing surface by a distance (H PR ) of at least 30% of a seal radial span (H O ).
8 . The split ring seal of claim 1 wherein:
the first circumferential end and the second circumferential end form a joint; and
the circumferential channel has an open first end and an open second end.
9 . The split ring seal of claim 1 wherein:
a radial span (H C2 ) of the first surface is 15% to 40% of a seal radial span (H O ).
10 . The split ring seal of claim 1 wherein:
the first circumferential end and the second circumferential end form a shiplap joint.
11 . The split ring seal of claim 1 wherein:
the coating comprises a chromium-based coating layer.
12 . A machine including the split ring seal of claim 1 and further comprising:
an inner member;
an outer member encircling the inner member; and
a groove in the inner member, the split ring seal accommodated in the groove and contacting an inner diameter surface of the outer member.
13 . The machine of claim 12 being a gas turbine engine wherein:
the inner member is a seal carrier of a carbon seal system;
the seal carrier carries a carbon seal;
the carbon seal is biased into engagement with a seat that rotates with an associated spool of the engine; and
the outer member is a stationary seal support from which the seal carrier is spring biased.
14 . The machine of claim 12 wherein:
the groove has a first side surface, a second side surface, and a base surface;
the first axial end face faces or contacts the first side surface;
the second axial end face faces or contacts the second side surface;
the groove first side surface is of ais a distal portion of the inner member having a first outer diameter surface; and
the groove second side surfaces is of a proximal portion of the inner member having a second outer diameter surface.
15 . The machine of claim 14 wherein:
the second axial end face has a radially inwardly and axially outwardly open inner diameter recess extending radially inward from the first sealing surface; and
a radial span (H RW ) of the inner diameter recess radially outward from the first outer diameter surface is greater than a radial span (H G ) between the second outer diameter surface and the inner diameter surface of the outer member.
16 . The machine of claim 14 wherein:
the second axial end face has a radially inwardly and axially outwardly open inner diameter recess extending radially inward from the first sealing surface;
a depth (D R ) of the inner diameter recess is 10% to 30% of a length (L G ) of the groove; and
a length (L 1 ) from the inner diameter recess to an axial end of the protrusion is greater than the groove length (L G ).
17 . The machine of claim 14 wherein:
a radial span (H IDG ) between the groove base surface and the seal inner diameter surface is greater than a radial span (H G ) between the first outer diameter surface and the inner diameter surface of the outer member.
18 . The machine of claim 14 wherein:
a radial overlap (H RO ) of the distal portion of the inner member and the seal is 15% to 25% of a seal radial span (H O ).
19 . The machine of claim 14 wherein:
a radial span (H PO ) between an underside of the protrusion to the sealing surface of the outer diameter surface is greater than twice a radial span (H GB ) between the second outer diameter surface at a contact with the second axial end face and the inner diameter surface of the outer member;
a seal axial span (L O ) is between 110% and 150% of a groove axial length; and
the groove has a low pressure side bevel having a radial span (H B ) of 10% to 35% of a radial span (H s1 ) of the seal outboard of the circumferential channel.
20 . A method for using the machine of claim 12 , the method comprising:
creating a pressure difference across the split ring seal; and
the pressure difference acting to bias the second axial end face into sealing contact with a sidewall of the groove.
21 . A gas turbine engine comprising:
a carbon seal system having:
a seat;
a carbon seal;
an inner member being a seal carrier carrying the carbon seal and having a groove;
an outer member being a seal support encircling the inner member;
one or more bias springs axially biasing the seal carrier from the support to bias the seal into engagement with the seat; and
a split ring seal accommodated in the groove and contacting an inner diameter surface of the seal support and comprising:
a first circumferential end and a second circumferential end;
an inner diameter surface and an outer diameter surface, the outer diameter surface having a sealing surface; and
a first axial end face and a second axial end face,
wherein:
the first axial end face has:
a first section;
a second section outboard of the first section; and
an axial protrusion between the first section and the second section; and
the second axial end face has:
a first surface;
a second surface radially outboard of the first surface;
a circumferential channel between the first surface and the second surface; and
a plurality of channels extending radially outward from the circumferential channel to an outermost section of the outer diameter surface.
22 . The gas turbine engine of claim 21 wherein:
the groove has a first side surface, a second side surface, and a base surface;
the first axial end face faces or contacts the first side surface;
the second axial end face faces or contacts the second side surface;
the groove first side surface is a distal portion of the inner member having a first outer diameter surface; and
the groove second side surfaces is of a proximal portion of the inner member having a second outer diameter surface.