Sprag clutch assembly of gas turbine engine
A clutch assembly is provided that includes inner and outer races. The clutch assembly also includes sprags concentrically disposed in an annular space between the inner and outer races. Each sprag includes an inner step and an outer step. The clutch assembly further includes a segmented ring configured to radially expand and radially contract. The clutch assembly also includes a resilient element configured to exert a force on the segmented ring and affect expansion or contraction of the segmented ring. In a disengaged state, the segmented ring is configured to contract to exert a radially inward pressure on the inner step of each sprag to create a gap between each sprag and the outer race. In an engaged state, the segmented ring is configured to expand to exert radially outward pressure on the outer step of each sprag to wedge each sprag between the inner and outer races.
1 . A clutch assembly comprising:
an inner race having an outer surface;
an outer race disposed concentrically around the inner race, the outer race having an inner surface;
a plurality of sprags circumferentially disposed in an annular space between the outer surface of the inner race and the inner surface of the outer race, each of the plurality of sprags comprising a radially inner step and a radially outer step;
a segmented ring disposed circumferentially around the outer surface of the inner race, wherein the segmented ring is configured to radially expand for engagement with the radially outer step of each of the plurality of sprags and radially contract for engagement with the radially inner step of each of the plurality of sprags; and
a resilient element configured to exert a force on the segmented ring and affect at least one of radial expansion or radial contraction of the segmented ring,
wherein, in a disengaged state of the clutch assembly, the segmented ring is configured to radially contract to exert a radially inward pressure on the radially inner step of each of the plurality of sprags to create a gap between each of the plurality of sprags and the inner surface of the outer race, and
wherein, in an engaged state of the clutch assembly, the segmented ring is configured to radially expand to exert radially outward pressure on the radially outer step of each of the plurality of sprags to wedge each sprag between the outer surface of the inner race and the inner surface of the outer race.
2 . The clutch assembly of claim 1 , wherein, in the disengaged state, the radially inward pressure on the radially inner step pivots each of the plurality of sprags about an inner pivot point.
3 . The clutch assembly of claim 1 , wherein, in the engaged state, the radially outward pressure on the radially outer step pivots each of the plurality of sprags about an outer pivot point.
4 . The clutch assembly of claim 1 , wherein the resilient element is configured to exert a radially inward force on the segmented ring.
5 . The clutch assembly of claim 4 , wherein, in the engaged state, a centrifugal force radially expands the segmented ring, and the centrifugal force exceeds the radially inward force of the resilient element.
6 . The clutch assembly of claim 4 , wherein, in the engaged state, a pressure-actuated system radially expands the segmented ring, and a radially outward force from the pressure-actuated actuation system exceeds the radially inward force of the resilient element.
7 . The clutch assembly of claim 6 , wherein the pressure-actuated system comprises at least one piston configured to exert the radially outward force on the segmented ring.
8 . The clutch assembly of claim 1 , wherein the segmented ring is divided into a plurality of arc-shaped segments.
9 . The clutch assembly of claim 1 , wherein, in the engaged state, torque is transmitted from the inner race to the outer race via a contact line of each of the plurality of sprags between the outer surface of the inner race and the inner surface of the outer race.
10 . The clutch assembly of claim 1 , wherein the radially inner step and the radially outer step extend axially from a face of each of the plurality of sprags.
11 . A clutch assembly comprising:
an inner race;
an outer race disposed concentrically around the inner race;
a plurality of sprags circumferentially disposed in an annular space between the inner race and the outer race;
a segmented ring disposed circumferentially around the inner race, wherein the segmented ring is configured to radially expand and radially contract for engagement with the plurality of sprags; and
a resilient element configured to exert a force on the segmented ring and affect at least one of radial expansion or radial contraction of the segmented ring,
wherein, in a disengaged state of the clutch assembly, radial contraction of the segmented ring pivots each of the plurality of sprags such that a gap is disposed between each of the plurality of sprags and the outer race, and
wherein, in an engaged state of the clutch assembly, radial expansion of the segmented ring pivots each of the plurality of sprags to form a contact line between the inner race and the outer race, and wherein torque is transmitted via the contact line.
12 . The clutch assembly of claim 11 , wherein each of the plurality of sprags comprises a radially inner step and a radially outer step.
13 . The clutch assembly of claim 12 , wherein the radially inner step and the radially outer step extend axially from a face of each of the plurality of sprags.
14 . The clutch assembly of claim 12 , wherein, in the disengaged state, the segmented ring applies a radially inward pressure on the radially inner step.
15 . The clutch assembly of claim 12 , wherein, in the engaged state, the segmented ring applies a radially outward pressure on the radially outer step.
16 . The clutch assembly of claim 11 , wherein the resilient element is configured to exert a radially inward force on the segmented ring.
17 . The clutch assembly of claim 16 , wherein, in the engaged state, a centrifugal force radially expands the segmented ring, and the centrifugal force exceeds the radially inward force of the resilient element.
18 . The clutch assembly of claim 16 , wherein, in the engaged state, a pressure-actuated system radially expands the segmented ring, and the pressure-actuated system is configured to exert a radially outward force on the segmented ring that exceeds the radially inward force of the resilient element.
19 . The clutch assembly of claim 11 , wherein the segmented ring is divided into a plurality of arc-shaped segments.
20 . A clutch assembly comprising:
an inner race;
an outer race disposed concentrically around the inner race;
a plurality of sprags circumferentially disposed in an annular space between the inner race and the outer race, each of the plurality of sprags comprising a radially inner step and a radially outer step; and
a segmented ring disposed circumferentially around the inner race, wherein the segmented ring is configured to radially expand for engagement with the radially outer step of each of the plurality of sprags and radially contract for engagement with the radially inner step of each of the plurality of sprags,
wherein, in a disengaged state of the clutch assembly, the segmented ring radially contracts to exert a radially inward pressure on the radially inner step of each of the plurality of sprags and pivots each of the plurality of sprags to create a gap between each of the plurality of sprags and the outer race, and
wherein, in an engaged state of the clutch assembly, the segmented ring radially expands to exert radially outward pressure on the radially outer step of each of the plurality of sprags and pivots each of the plurality of sprags to wedge each of the plurality of sprags between the inner race and the outer race.