Prosecution Insights
Last updated: April 19, 2026
Application No. 18/478,590

MAGNET RETENTION IN EXTERIOR ROTOR ELECTRIC MACHINES

Final Rejection §103
Filed
Sep 29, 2023
Examiner
STEFANON, JUSTIN
Art Unit
2834
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Rolls-Royce
OA Round
2 (Final)
51%
Grant Probability
Moderate
3-4
OA Rounds
3y 8m
To Grant
99%
With Interview

Examiner Intelligence

Grants 51% of resolved cases
51%
Career Allow Rate
94 granted / 183 resolved
-16.6% vs TC avg
Strong +48% interview lift
Without
With
+47.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 8m
Avg Prosecution
50 currently pending
Career history
233
Total Applications
across all art units

Statute-Specific Performance

§101
1.0%
-39.0% vs TC avg
§103
34.1%
-5.9% vs TC avg
§102
38.4%
-1.6% vs TC avg
§112
25.2%
-14.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 183 resolved cases

Office Action

§103
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 Applicant’s arguments, see page 5, filed 11/26/2025, with respect to rejections under 35 USC 112 have been fully considered and are persuasive. The rejections of claims 7, 9, and 10 have been withdrawn. Applicant’s arguments with respect to rejections of claims 1-10 under 35 USC 102 and 103 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Specification The disclosure is objected to because of the following informalities: in paragraph [0083] the ‘first portion’ is referred to with numeral 1290A, which does not appear in the drawings; elsewhere, the ‘first portion’ is referred to with 1292A. Appropriate correction is required. Drawings The drawings are objected to as failing to comply with 37 CFR 1.84(p)(5) because they include the following reference character(s) not mentioned in the description: 341, 352, 441, 442 452, 472, 541, 553, 556, 572, 581, 1152, 1153, 1154, 1251, 1252, 1339, 1352, 1353, 1439, 1451, 1452, 1493, 1539, 1541, 1542, 1551, 1552, 1553, 1554, 1555, 1556, 1572, 1581A, 1581B. Corrected drawing sheets in compliance with 37 CFR 1.121(d), or amendment to the specification to add the reference character(s) in the description in compliance with 37 CFR 1.121(b) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance. Claim Rejections - 35 USC § 103 The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. Claims 1 and 3-8 are rejected under 35 U.S.C. 103 as being unpatentable over LI (US 20220181931 A1) in view of POULIN (previously cited; US 7898136). Regarding claim 1, LI discloses an electric machine (motor 100) of a gas-turbine engine (“[S]tatements in the preamble reciting the purpose or intended use of the claimed invention must be evaluated to determine whether or not the recited purpose or intended use results in a structural difference (or, in the case of process claims, manipulative difference) between the claimed invention and the prior art”. See, e.g., In re Otto, 312 F.2d 937, 938, 136 USPQ 458, 459 (CCPA 1963). The intended-use limitation “of a gas-turbine engine” is of no significance to the structure of the electric machine.), the electric machine comprising: a stator (101) comprising windings (para [0034]); a rotor (102) configured to rotate around the stator (101) (see Fig. 3), the rotor (102) comprising: a rotor body (106) having an inner surface and an outer surface (Fig. 3) PNG media_image1.png 483 778 media_image1.png Greyscale magnets (118) on the inner surface of the rotor body (106), the magnets (118) having an inner surface (215) and an outer surface (see Figs. 3 and 6); and a retention band (116) on the inner surface of the magnets (118) and configured to retain the magnets (118) to the rotor body (106) (see Fig. 6) body, However, LI does not specifically disclose the retention band disposed between the inner surface of the magnets and the windings. POULIN discloses an electric machine with a rotor 10 configured to rotate around a stator (col. 2, lines 65-66) with a retention band 16 disposed between the inner surface of the magnets and the stator (see Fig. 1 and 4) PNG media_image2.png 598 553 media_image2.png Greyscale PNG media_image3.png 602 538 media_image3.png Greyscale It 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 to provide the machine of LI with the retention band disposed between the inner surface of the magnets and the windings, similar to that of POULIN. A person having ordinary skill in the art to which the claimed invention pertains would have been motivated to make such modification in order to provide a secure magnet retention system that does not require an overly complex mold, as taught by POULIN (col. 4, lines 9-20). Regarding claim 3, LI in view of POULIN teaches the electric machine of claim 1, wherein LI discloses the retention band (116) seals the magnets (118) into the rotor (102) (see Fig. 6; the shoulders at 212 and 214 seal the magnets to the rotor as broadly claimed). Regarding claim 4, LI in view of POULIN teaches the electric machine of claim 1, wherein POULIN discloses the retention band includes: a first portion 308 positioned at a first end of the magnets 14 and configured to radially retain the first end of the magnets to the inner surface of the rotor body 12 (see Fig. 17); and a center portion 306 extending from the first portion 308 along the inner surface of the magnets 14. Regarding claim 5, LI in view of POULIN teaches the electric machine of claim 4, wherein POULIN discloses the retention band includes: a second portion 310 positioned at a second end of the magnets 14 and configured to radially retain the second end of the magnets 14 to the inner surface of the rotor body 12, and wherein the center portion 306 connects the first portion 308 and the second portion 310 (see Fig. 17). PNG media_image4.png 214 562 media_image4.png Greyscale Regarding claim 6, LI in view of POULIN teaches the electric machine of claim 4, wherein POULIN discloses a radial thickness of the center portion is less than a radial thickness of the first portion (see Fig. 7). Regarding claim 7, LI in view of POULIN teaches the electric machine of claim 4, wherein LI discloses the magnets (118) are profiled to include a shoulder (212/214) that is opposite to a geometry of the first portion the retention band (116). Regarding claim 8, LI in view of POULIN teaches the electric machine of claim 1, wherein li discloses the rotor (102) further comprises: one or more retention rings (107) attached to the rotor body (106) and configured to radially retain the magnets (118) to the inner surface of the rotor body (106), the one or more retention rings (107) formed of a different material than the retention band (116) (see paras. [0037] and [0049]). Claims 2 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over LI in view of POULIN and further in view of SABAN (US 8237320 B2; previously cited). Regarding claim 2, LI in view of POULIN teaches the electric machine of claim 1. However, LI in view of POULIN does not teach the retention band is formed of glass reinforced composite. SABAN discloses an electric machine with a rotor magnet retention band (212) formed of glass reinforced composite (see col. 12, lines 12-28). It 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 to provide the sleeve of LI with one made of glass reinforced composite similar to that of SABAN. LI discloses the rotor being formed of carbon fiber composite (see para. [0037]). A person having ordinary skill in the art to which the claimed invention pertains would have been motivated to make such modification in order to protect rotor components as well as provide structural support to rotor components and provide high strength, corrosion resistance, and abrasion resistance and [such materials] are not magnetically permeable. as taught by SABAN (see col. 12, lines 12-28 and col. 31, lines 45-54). Regarding claim 11, LI in view of POULIN teaches the electric machine of claim 1. LI discloses the rotor being formed of carbon fiber composite (see para. [0037]). However, LI in view of POULIN does not teach the retention band comprises a pre-cured composite installed via a thermal interference fit. SABAN discloses an electric machine with a rotor magnet retention band (212) formed of glass reinforced composite (see col. 12, lines 12-28) assembled by an interference fit (see col. 30, lines 14-23). (regarding “pre-cured” and “thermal”, SABAN discloses the claimed structure. These Product-by-Process Claims are limited only by the structure implied by the steps; see MPEP 2113 "[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process." In re Thorpe) It 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 to provide the sleeve of LI in view of POULIN with one made of pre-cured composite installed via a thermal interference fit, similar to that of SABAN. A person having ordinary skill in the art to which the claimed invention pertains would have been motivated to make such modification in order to protect rotor components as well as provide structural support to rotor components and provide high strength, corrosion resistance, and abrasion resistance and [such materials] are not magnetically permeable, as taught by SABAN (see col. 12, lines 12-28 and col. 31, lines 45-54) and to provide a seal against intrusion of fluid, as taught by SABAN (see col. 30, lines 14-23). Claims 9 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over LI in view POULIN and further in view of KLEMEN (US 11130456 B2; previously cited). Regarding claim 9, LI in view of POULIN teaches the electric machine of claim 1, wherein the rotor rotates about a longitudinal axis. However, LI in view of POULIN does not teach the gas-turbine engine comprises: a core section comprising at least one compressor and at least one turbine that both rotate about a longitudinal axis of the gas-turbine engine; a core vane assembly coupled to the core section, wherein the core vane assembly comprises a plurality of core vanes configured to modify core fluid flow; and a fan connected to the core section and configured to be rotated by the at least one turbine, rotation of the fan providing thrust to a vehicle that includes the gas-turbine engine, wherein the electric machine is integrated into the core vane assembly and positioned in the core section aft of the fan and fore of the at least one compressor, and. KLEMEN discloses an electric machine (38) of a gas-turbine engine (10) comprising: a core section comprising at least one compressor (14) and at least one turbine (18) that both rotate about the longitudinal axis (25) of the gas-turbine engine; a core vane assembly coupled to the core section, wherein the core vane assembly comprises a plurality of core vanes (56) configured to modify core fluid flow; and a fan (12) connected to the core section and configured to be rotated by the at least one turbine, rotation of the fan providing thrust to a vehicle that includes the turbine engine, wherein the electric machine (38) is integrated into the core vane assembly and positioned in the core section aft of the fan and fore of the at least one compressor (see col. 6, lines 61-64). PNG media_image5.png 334 586 media_image5.png Greyscale It 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 to provide the gas-turbine engine of KLEMEN with an electric machine similar to that of LI in view of POULIN. A person having ordinary skill in the art to which the claimed invention pertains would have been motivated to make such modification in order to provide a smaller size (e.g., in the azimuthal direction) of each individual magnet, which can lead to better control of the magnetic flux generated by the magnets, leading to improved efficiency of the electric motor, as taught by LI (see para [0053]). Regarding claim 10, LI in view of POULIN and further in view of KLEMEN teaches the electric machine of claim 9, wherein KLEMEN discloses the rotor is mechanically rotated via the fan or a shaft (1046) that is rotationally coupled to the fan (see Fig. 15). PNG media_image6.png 502 563 media_image6.png Greyscale 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 JUSTIN STEFANON whose telephone number is (703)756-4648. The examiner can normally be reached Monday - Thursday and alternate Fridays 8AM - 5PM EDT. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Oluseye Iwarere can be reached at (571) 270-5112. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /JUSTIN STEFANON/Examiner, Art Unit 2834 /OLUSEYE IWARERE/Supervisory Patent Examiner, Art Unit 2834
Read full office action

Prosecution Timeline

Sep 29, 2023
Application Filed
Aug 23, 2025
Non-Final Rejection — §103
Nov 26, 2025
Response Filed
Mar 07, 2026
Final Rejection — §103 (current)

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12494684
ROTOR OF AN ELECTRIC MACHINE
2y 5m to grant Granted Dec 09, 2025
Patent 12451742
METHOD AND APPARATUS FOR COOLING A ROTOR ASSEMBLY
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Patent 12316190
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2y 5m to grant Granted May 27, 2025
Patent 9650015
BELT RETRACTOR FOR A VEHICLE SAFETY BELT
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Patent 9635986
SPINDLE AND ADAPTER FOR ROLL PAPER PRODUCT DISPENSERS
2y 5m to grant Granted May 02, 2017
Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
51%
Grant Probability
99%
With Interview (+47.7%)
3y 8m
Median Time to Grant
Moderate
PTA Risk
Based on 183 resolved cases by this examiner. Grant probability derived from career allow rate.

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