DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Arguments
The 103 rejection of claims 1-4, 6, and 8-9 over Rougier (FR 3109407) in view of Venter (US 2009/0293449) is overcome because Venter does not teach “blocking doors to block the engine airflow from flowing into the power turbine.” “Blocking door” is a specific structure known to one of ordinary skill in the art, and Venter does not teach it.
The Applicant argues that “The Negri reference does not describe blocking doors that in a second mode restrict airflow to stop the power turbine and cease driving the open propulsor rotor via the power turbine shaft.” This argument is not persuasive. Negri teaches “the gate 56 will extend inside the duct counter to the flow of the gases flowing in the duct 22 and will thus promote the removal of the gases by scoop effect” (¶60), and thus teaches “restrict airflow.” Negri further teaches “The rotor of the low-pressure turbine is then no longer or not driven by these gases” (¶15), and thus teaches “stop the power turbine and cease driving the open propulsor rotor via the power turbine shaft.” It is noted that Negri relates to shaft or gearbox breakage wherein the rotation of the fan may no longer be linked to the rotation of the shaft. Nonetheless, the claims do not require that the open propulsor rotor is stopped by the blocker door, only that the power turbine will “cease driving the open propulsor rotor.” Further, the system of Negri responds directly to an overspeeding condition and does not require shaft breakage (¶74). Thus, other conditions, such as loss of pitch control (see US 2009/0285686, ¶5 “loss of pitch control and the turning of blades to low pitch could cause significant drag and overspeed conditions”), could cause overspeeding and trigger the system of Negri as applied to Lima. Base reference Lima has variable pitch propeller blades (¶64) and thus loss of pitch control is a possible event in Lima. In this case, the blocker doors scooping out the flow to the power turbine would stop the power turbine, the shaft, and the open propulsor rotor.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-4 and 6-7 are rejected under 35 U.S.C. 103 as being unpatentable over Lima (US 2023/0079110) in view of Negri (US 2017/0284306).
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Regarding claim 1, Lima discloses:
An aircraft propulsion system (1, ¶1), comprising:
a core engine (3, ¶38) defining an engine airflow path, the core engine comprising a first spool section (¶38) having a first compressor (high-pressure compressor 5), a first turbine (high-pressure turbine 7) and a first spool shaft (¶38, high-pressure shaft) coupled to the first compressor and the first turbine;
a power turbine assembly disposed downstream (¶39 “downstream of the intermediate pressure turbine,” which is part of the low-pressure body, which turbine is downstream of the high-pressure turbine) of the first turbine, the power turbine assembly comprising a power turbine (¶39 free power turbine) coupled to a power turbine shaft (¶39 power transmission shaft);
an open propulsor rotor (2, ¶36) disposed upstream of the power turbine assembly and coupled to the power turbine shaft (¶39), the open propulsor rotor comprising a plurality of rotor blades (21, ¶41);
…
a transition duct (flow path along 8 as shown in Fig 1) configured to receive an engine airflow from the first turbine…
Lima does not disclose:
a power turbine isolation system disposed downstream of the first turbine and upstream of the power turbine, the power turbine isolation system comprising,
a flow diverter comprising a plurality of blocking doors selectively configured to, in a first mode close each of the plurality of blocking doors to cause engine airflow from the first turbine to flow into the power turbine to drive the power turbine and drive the open propulsor rotor via the power turbine shaft; and
in a second mode open each of the plurality of blocking doors to block the engine airflow from flowing into the power turbine to stop the power turbine and cease driving the open propulsor rotor via the power turbine shaft.
Lima discloses that the propulsor is driven via a gearbox (¶41).
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Negri teaches:
An overspeed protection system (¶7, ¶13-¶15) that protects the gearbox from overspeed (¶11) in the event of any overspeed event (¶70, ¶74). In a three-spool configuration, a discharge device of the overspeed protection system can be placed between the intermediate turbine and the low-pressure turbine (¶59). The device comprises an annular row of discharge valves (¶60) that discharge sufficient gas so that the turbine is no longer driven by combustion gases (¶15 “The rotor of the low-pressure turbine is then no longer or not driven by these gases”). The valves are pivotable around a shaft to block the flow path (¶65 “the gate 56 will extend inside the duct counter to the flow of the gases flowing in the duct 22 and will thus promote the removal of the gases by scoop effect”), as shown in Fig 4, and thus meet the limitation of a blocking door.
COMBINATION
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the system of Lima to include an overspeed protection system including an annular row of blocking doors, as taught by Negri, to obtain the benefit of overspeed protection.
Regarding claim 2, the system of Lima as modified by the overspeed protection system of Negri teaches:
the flow diverter is configured to, in the first mode, direct the engine airflow to the power turbine and block the engine airflow from flowing into a bypass airflow path (Negri: see Fig 3, ¶64).
Regarding claim 3, the system of Lima as modified by the overspeed protection system of Negri teaches:
the flow diverter is further configured to, in the second mode, direct the engine airflow into a bypass airflow path and prevent the engine airflow from flowing into the power turbine (Negri: see Fig 4, ¶65. In Lima, this flow is diverted to the exterior of the engine.).
Regarding claim 4, the system of Lima as modified by the overspeed protection system of Negri teaches:
the plurality of blocker doors (Negri: 56) are selectively movable into a first position associated with the first mode and a second position associated with the second mode (Negri: ¶61-¶65).
Regarding claim 6, the system of Lima as modified by the overspeed protection system of Negri teaches:
the core engine further comprises:
a second spool section having a second compressor (Lima: ¶38 low-pressure compressor 4), a second turbine (Lima: low-pressure turbine 8) disposed upstream of the power turbine assembly, and a second spool shaft (Lima: low-pressure shaft 9) coupled to the second compressor and the second turbine.
Regarding claim 7, the system of Lima as modified by the overspeed protection system of Negri does not explicitly teach:
the power turbine isolation system further comprises:
one or more extension ducts configured to receive the engine airflow in the second mode and direct the engine airflow outside the engine.
Lima discloses a substantial external casing 14 surrounding the turbine section and core engine. Negri teaches the blocking doors forcing the gases in the primary/core duct to flow outward to a secondary duct, i.e., radially outward of the casing surrounding the turbine. Negri shows the outward flow schematically, without sufficient detail to discern a path through a duct. Nonetheless, when the teaching of Negri is applied to Lima, a duct is necessary to allow gas to flow from the core duct to outside of the core duct.
MODIFICATION
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have further modified the system of Lima as modified by the overspeed protection system of Negri to have one or more extension ducts though the external casing 14 of Lima to allow the gases to flow out of the core duct.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Lima (US 2023/0079110) in view of Gainford (US 2010/0066098).
Regarding claim 8, Lima and Negri do not disclose:
a brake mechanism selectively configured to inhibit rotation of the open propulsor rotor in the second mode.
Gainford teaches:
A gas turbine engine having an electrical system that is powered by the propeller drive shaft. The electrical system can shift into a high load state to control rotor overspeed or to act as a parking brake on the ground to stop the propeller for personnel safety (¶34).
COMBINATION
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the engine of Lima and Negri by further including an electrical system powered by the propellor drive shaft to provide electricity for various purposes, and to include a high load state to control overspeed and act as a parking brake. The system is an electrical brake mechanism. In an overspeed event, both the blocker doors and the brake activate. The combination does not include teaching of activating the blocker doors on the ground.
Allowable Subject Matter
Claim 9 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter: Claim 9 recites “the brake mechanism is configured to be operable only when the aircraft propulsion system is on the ground.” In the combination with Gainford, the brake system is used for overspeed control and ground braking. The blocker doors are used for overspeed control, i.e. during flight. The combination does not teach using the brake only on the ground. Although Rougier and Venter taught a ground brake, Venter did not teach a blocker door to block the engine airflow from flowing into the power turbine.
Pertinent Prior Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Regarding claim 1, Rolling (US 10,711,791) discloses:
An aircraft propulsion system (col 3 lines 30-31 “turbofan engine”), comprising:
a core engine defining an engine airflow path, the core engine comprising a first spool section (col 3 lines 43-48) having a first compressor (34), a first turbine (38) and a first spool shaft (32) coupled to the first compressor and the first turbine;
a power turbine assembly disposed downstream of the first turbine (see Fig 1), the power turbine assembly comprising a power turbine (auxiliary turbine 72) coupled to a power turbine shaft (auxiliary turbine shell 80);
an open propulsor rotor (76) …and coupled to the power turbine shaft (col 4 lines 48-54), the open propulsor rotor comprising a plurality of rotor blades (see 76 in Fig 2);
a power turbine isolation system (diverter 60, col 3 line 56-col 4 line 65) disposed downstream of the first turbine and upstream of the power turbine, the power turbine isolation system comprising,
a transition duct (between diverter 60 and outer casing) configured to receive an engine airflow from the first turbine (see arrows indicating flow in Fig 2), and a flow diverter (60) comprising a plurality of blocking doors (“a plurality of overlapping plates 62 configured in a frustoconical orientation”) selectively configured to, in a first mode (see Fig 1) close each of the plurality of blocking doors to cause engine airflow from the first turbine to flow into the power turbine to drive the power turbine and drive the open propulsor rotor via the power turbine shaft (col 2 lines 41-65); and in a second mode (see Fig 1) open each of the plurality of blocking doors to block the engine airflow from flowing into the power turbine to stop the power turbine and cease driving the open propulsor rotor via the power turbine shaft (col 4 lines 8-30).
Rolling does not disclose:
[the propulsor rotor is] disposed upstream of the power turbine assembly
Rolling discloses an unducted configuration (see Fig 2) with an aft fan (pusher) driven by a rotating casing.
Lima teaches:
an open rotor propellor driven by a rotating casing, which propeller may be upstream (puller) or downstream (pusher) of the driving turbine (¶41).
COMBINATION
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TOPAZ L ELLIOTT whose telephone number is (571)270-5851. The examiner can normally be reached Monday-Friday 9 a.m. - 4 p.m. EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Ibrahime Abraham can be reached on (571) 270-5569. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/TOPAZ L. ELLIOTT/Primary Examiner, Art Unit 3761
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