Secondary oil system for gas turbine engine

• US 4,858,426 A
• Filed: 07/21/1988
• Issued: 08/22/1989
• Est. Priority Date: 07/21/1988
• Status: Expired due to Term

• Current Assignee: Rolls-Royce Corporation (Rolls-Royce Holdings Plc)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Holcomb, Warren N.
• Primary Examiner(s): Stout, Donald E.
• Application Number:
  US07/222,994
• Time in Patent Office: 397 Days
• Field of Search: 60/39.08, 60/39.091, 60/39.83, 184/6.11, 184/6.4, 184/65, 384/473
• US Class Current: 60/39.08
• CPC Class Codes: F01D 25/18 Lubricating arrangements of machines or engines in general F01M

Abstract

A secondary oil system for a flight propulsion gas turbine engine having vertical and horizontal flight modes includes an annular reservoir tank in a bearing sump of the engine around a rotor shaft of the engine, a pipe connected to the primary oil system of the engine extending through the reservoir tank and conducting a primary oil flow to a bearing in the sump, an inlet orifice at the top of the reservoir tank in each of the horizontal and vertical flight modes between the pipe and the reservoir tank for conducting a part of the primary oil flow to the reservoir tank, a discharge orifice at the bottom of the reservoir tank in each of the vertical and horizontal flight modes having a flow are limiting a gravity induced secondary oil flow from the reservoir tank to a secondary oil flow rate substantially less than the primary oil flow rate, and a passage conducting the gravity induced secondary oil flow to the bearing in the sump. The secondary oil flow persists after primary oil flow stops until the reservoir tank completely drains.

Claims

1. In a gas turbine engine for flight propulsion in a selected one of a horizontal flight mode and a vertical flight mode,

said gas turbine engine having

a rotor shaft on an axis of said engine oriented horizontally in said horizontal flight mode and vertically in said vertical flight mode,

a generally annular housing of said engine surrounding said rotor shaft,

seal means at opposite longitudinal ends of said housing engaging said rotor shaft and defining therebetween an annular sump around said rotor shaft,

a bearing in said sump including an inner race on said rotor shaft and an outer race on said housing and a plurality of anti-friction elements between said inner and said outer races,

a primary oil system including a pipe conducting a primary oil flow at a primary oil flow rate to a plurality of nozzles in said sump wherein said primary oil flow cools and lubricates said bearing, and an annular reservoir tank disposed in said sump and attached to said housing,

the improvement comprising:

a vent and overflow disposed at the top of said reservoir tank in each of said horizontal and said vertical flight modes of said engine and connected to said sump whereby the pressure in said reservoir tank is always equal to the pressure in said sump,

means defining an inlet orifice between said pipe and said reservoir tank at the top of said reservoir tank in each of said horizontal and said vertical flight modes of said engine whereby a part of said primary oil flow is conducted into said reservoir tank,

means defining a discharge orifice in said reservoir tank at the bottom thereof in each of said horizontal and said vertical flight modes of said engine whereby gravity induces a continuous secondary oil flow from said reservoir tank at a secondary flow rate substantially less than said primary oil flow rate in each of said horizontal and said vertical flight modes of said engine, and

means defining a passage between said discharge orifice and said sump conducting said gravity induced secondary oil flow from said reservoir tank to said bearing.

2. In a gas turbine engine for flight propulsion in a selected one of a horizontal flight mode and a vertical flight mode,

said gas turbine engine having

a rotor shaft on an axis of said engine oriented horizontally in said horizontal flight mode and vertically in said vertical flight mode,

a generally annular housing of said engine surrounding said rotor shaft,

seal means at opposite longitudinal ends of said housing engaging said rotor shaft and defining therebetween an annular sump around said rotor shaft,

a bearing in said sump including an inner race on said rotor shaft and an outer race on said housing and a plurality of anti-friction elements between said inner and said outer races,

a primary oil system including a passage in said housing connected to a supply of oil and a passage system in said housing connected to a plurality of nozzles in said sump operative to discharge jets of oil at a primary oil flow rate for cooling and lubricating said bearing in said sump, and

an annular reservoir tank disposed in said sump and attached to said housing, the improvement comprising:

an overflow and vent disposed at the top of said reservoir tank in each of said horizontal and said vertical flight modes of said engine and connected to said sump whereby the pressure in said reservoir tank is always equal to the pressure in said sump,

means defining an intermediate pipe in said reservoir tank having one end connected to said passage in said housing and the other end connected to said passage system in said housing whereby said intermediate pipe conducts said primary oil flow from said passage to said passage system,

means defining an inlet orifice in said intermediate pipe located generally at the top of said reservoir tank in each one of said horizontal and said vertical flight modes of said engine whereby a part of said primary oil flow is conducted into said reservoir tank,

means defining a discharge orifice in said reservoir tank at the bottom thereof in each of said horizontal and said vertical flight modes of said engine whereby gravity induces a continuous secondary oil flow from said reservoir tank at a secondary flow rate substantially less than said primary oil flow rate in each of said horizontal and vertical flight modes of said engine, and

means defining a passage in said housing between said discharge orifice and said sump conducting said gravity induced secondary oil flow from said reservoir tank to said bearing.