Pressurized oil supply for propeller engine system
AssigneePratt & Whitney Canada Corp.
InventorDavid Waddleton
Life of this patent
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Abstract
A system and method for providing pressurised oil during non-feathered in-flight shutdown conditions in a variable-pitch aircraft propeller engine. A secondary pump provides pressurised oil substantially independent of an engine main oil circuit.
Claims22
A backup system for providing pressurised oil to a propeller control system during an in-flight shutdown of an engine, the propeller control system including an oil circuit normally fed by a propeller pump having an outlet connected to a propeller control unit and an inlet connected to a supply of pressurised oil during engine operation, the backup system comprising a secondary pump selectively connectable to said oil circuit and adapted to selectively supply said oil circuit with a flow of pressurized oil during said in-flight engine shutdown, the secondary pump including an ejector pump having an ejector pump inlet and an injector pump outlet selectively connectable in fluid flow communication with said oil circuit, the oil in the oil circuit being used as a motive fluid for the ejector pump to passively draw additional oil in the oil circuit.
A system for providing a secondary pressurized oil supply to an engine during in-flight shutdown conditions, the engine having a main pressurised oil circuit comprising a main pump operational at least during regular engine operation, the system comprising a secondary oil circuit selectively connectable to the main oil circuit in the event of an engine in-flight shutdown, the secondary circuit including a secondary pump adapted to pressurise oil in the secondary circuit to a predetermined pressure at least during said in-flight shutdown conditions, the predetermined pressure exceeding a nominal oil pressure in the main pressurised oil circuit during said in-flight shutdown conditions, wherein the secondary pump is selectively connectable to an inlet of said main pump to provide a pressurised oil supply at said inlet of said main pump during said in-flight shutdown conditions, and wherein said secondary pump comprises an ejector pump having an ejector pump inlet and an ejector pump outlet, said ejector pump inlet and said ejector pump outlet being respectively connected in selective fluid flow communication with an outlet and an inlet of the main pump.
A system as defined in clam 9, wherein said sump is located in a propeller reduction gear box, and wherein said ejector pump is located at a lower level than a scavenge return line of said sump.
A turboprop engine comprising a propeller having a number of variable pitch blades, a pitch control system for governing the operation of said variable pitch blades, said pitch control system employing a pressurized fluid as a means of system actuation, a propeller pump having an outlet for providing a pressurized fluid supply to said pitch control system, a main pressurized fluid source for providing a pressurized fluid supply to an inlet of said propeller pump, and a pressurized fluid back-up system for enabling operation of the pitch control system during in-flight engine shutdown conditions when said main source of pressurized fluid is unavailable, said pressurized fluid back-up system comprising a secondary source of pressurized fluid available to provide a pressurized fluid supply to said propeller pump inlet during in-flight shutdown, and a switching unit having a first state in which said main source of pressurized fluid is connected to the propeller pump inlet and said secondary source of pressurized fluid is disconnected from the propeller pump inlet, and a second state in which the secondary source of pressurized fluid is connected, to said propeller pump inlet, while said main source of pressurized fluid, is disconnected from the propeller pump inlet, said secondary source of pressurized fluid comprises a passive pump driven by surplus fluid supplied by said propeller pump.
A method for providing pressurised oil during in-flight shutdown of a variable pitch propeller engine, comprising the steps of:
- a) providing a propeller pump adapted to supply pressurized oil during engine operation from a main pressurised oil circuit to a propeller pitch actuation system, upon in-flight shutdown of the engine, b) selectively connecting the propeller pump to a secondary pressurized fluid circuit, the circuit including a an ejector pump operable independently of operation of the engine to supply pressurised oil during said engine shutdown and c) using surplus propeller pump flow as a motive fluid to operate the ejector pump.
A backup system for providing pressurised oil to a propeller control system during an in-flight shutdown of an engine, the propeller control system including a propeller pump having an outlet connected to a propeller control unit and an inlet connected to a supply of pressurised oil during engine operation, the backup system comprising a secondary pump connected to the propeller pump inlet and adapted to selectively supply said propeller pump inlet with a flow of pressurized oil during said in-flight engine shutdown, wherein said valve is responsive to fluid pressure at the inlet of the propeller pump for connecting said secondary pump to the inlet of the propeller pump when fluid pressure at the inlet of the propeller pump is below a predetermined value indicative of said in-flight engine shutdown.
Dependencies are inferred from the claim text.