Secondary oil system for gas turbine engine

Claim 2

In a flight propulsion gas turbine engine having a horizontal flight mode and a vertical flight mode, a rotor shaft supported on a case of said engine by a bearing for rotation about a rotor axis of said engine oriented horizontally in said horizontal flight mode and vertically in said vertical flight mode, and a primary oil system for lubricating said bearing, a secondary oil system for said bearing comprising: a secondary oil tank on said engine moveable therewith between a first position corresponding to said vertical flight mode and a second position corresponding to said horizontal flight mode, inlet means connecting said secondary oil tank to said primary oil system whereby said secondary oil tank is supplied with a fraction of the oil flow in said primary oil system, a discharge orifice in said secondary oil tank located at the bottom thereof in each of said first and said second positions of said secondary oil tank so that oil in said secondary oil tank is induced by gravity to flow out through said discharge orifice in each of said vertical and said horizontal flight modes of said gas turbine engine, said discharge orifice limiting said gravity induced oil outflow from said secondary oil tank to a secondary oil flow constituting a small fraction of the oil flow in said primary oil system in each of said first and said second positions of said secondary oil tank, first partition means in said secondary oil tank defining a descent reservoir chamber connected to said discharge orifice in each of said first and said second positions of said secondary oil tank, and second partition means in said secondary oil tank operative to maintain a predetermined minimum volume of oil in said descent reservoir tank in said second position of said secondary oil tank so that said predetermined minimum is available to sustain said secondary oil flow when said engine transitions from said horizontal to said vertical flight mode.

Claim 3

In a flight propulsion gas turbine engine having a horizontal flight mode and a vertical flight mode, a rotor shaft supported on a case of said engine by a bearing for rotation about a rotor axis of said engine oriented horizontally in said horizontal flight mode and vertically in said vertical flight mode, and a primary oil system for lubricating said bearing, a secondary oil system for said bearing comprising: a secondary oil tank on said engine moveable therewith between a first position corresponding to said vertical flight mode and a second position corresponding to said horizontal flight mode, inlet means connecting said secondary oil tank to said primary oil system whereby said secondary oil tank is supplied with a fraction of the oil flow in said primary oil system, a discharge orifice in said secondary oil tank located at the bottom thereof in each of said first and said second positions of said secondary oil tank so that oil in said secondary oil tank is induced by gravity to flow out through said discharge orifice in each of said vertical and said horizontal flight modes of said gas turbine engine, said discharge orifice limiting said gravity induced oil outflow from said secondary oil tank to a secondary oil flow constituting a small fraction of the oil flow in said primary oil system in each of said first and said second positions of said secondary oil tank, a first partition in said secondary oil tank extending vertically in said first position of said secondary oil tank and forming therein a descent reservoir on the side of said first partition facing said discharge orifice and a holding chamber on the opposite side thereof, first passage means across said first partition between said holding chamber and said descent reservoir at a predetermined height above a first side of said secondary oil tank forming the bottom thereof in said first position of said secondary oil tank so that oil in said holding chamber drains through said first passage means into said descent reservoir in said second position of said secondary oil tank and so that a portion of the volume of oil in said secondary oil tank is captured and retained in said holding chamber up to the height of said first passage means above said first side when said secondary oil tank moves with said engine from said second position of said secondary oil tank to said first position thereof, a second partition in said descent reservoir of said secondary oil tank extending vertically in said second position of said secondary oil tank and separating said first passage means from said discharge orifice, and second passage means across said second partition at a predetermined height above a second side of said secondary oil tank forming the bottom thereof in said second position of said secondary oil tank so that all of the oil in said reservoir chamber drains through said discharge orifice in said first position of said secondary oil tank and so that the minimum level of oil in said reservoir chamber in said second position of said secondary oil tank equals said predetermined height of said second passage means above said second side.

Claim 4

In a flight propulsion gas turbine engine having a horizontal flight mode and a vertical flight mode, a rotor shaft supported on a case of said engine by a bearing for rotation about a rotor axis of said engine oriented horizontally in said horizontal flight mode and vertically in said vertical flight mode, and a primary oil system for lubricating said bearing, a secondary oil system for said bearing comprising: a secondary oil tank on said engine moveable therewith between a first position corresponding to said vertical flight mode and a second position corresponding to said horizontal flight mode, inlet means connecting said secondary oil tank to said primary oil system whereby said secondary oil tank is supplied with a fraction of the oil flow in said primary oil system, a discharge orifice in said secondary oil tank located at the bottom thereof in each of said first and said second positions of said secondary oil tank so that oil in said secondary oil tank is induced by gravity to flow out through said discharge orifice in each of said vertical and said horizontal flight modes of said gas turbine engine, said discharge orifice limiting said gravity induced oil outflow from said secondary oil tank to a secondary oil flow constituting a small fraction of the oil flow in said primary oil system in each of said first and said second positions of said secondary oil tank, a first partition in said secondary oil tank extending vertically in said first position of said secondary oil tank and forming therein a descent reservoir on the side of said first partition facing said discharge orifice and a holding chamber on the opposite side thereof, first passage means across said first partition between said holding chamber and said descent reservoir at a predetermined height above a first side of said secondary oil tank forming the bottom thereof in said first position of said secondary oil tank so that oil in said holding chamber drains through said first passage means into said descent reservoir in said second position of said secondary oil tank and so that a portion of the volume of oil in said secondary oil tank is captured and retained in said holding chamber up to the height of said first passage means above said first side when said secondary oil tank moves with said engine from said second position of said secondary oil tank to said first position thereof, a second partition in said descent reservoir of said secondary oil tank extending vertically in said second position of said secondary oil tank and separating said first passage means from said discharge orifice, and second passage means across said second partition at a predetermined height above a second side of said secondary oil tank forming the bottom thereof in said second position of said secondary oil tank so that all of the oil in said reservoir chamber drains through said discharge orifice in said first position of said secondary oil tank and so that the minimum level of oil in said reservoir chamber in said second position of said secondary oil tank equals said predetermined height of said second passage means above said second side.

Claim 5

The secondary oil system recited in claim 2 wherein said secondary oil tank is an annular tank disposed in a sump of said gas turbine engine adjacent said bearing.