Prosecution Insights
Last updated: April 19, 2026
Application No. 18/578,459

STATOR CORE

Final Rejection §103
Filed
Jan 11, 2024
Examiner
VO, ETHAN NGUYEN
Art Unit
2834
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Dyson Technology Limited
OA Round
2 (Final)
69%
Grant Probability
Favorable
3-4
OA Rounds
2y 6m
To Grant
93%
With Interview

Examiner Intelligence

Grants 69% — above average
69%
Career Allow Rate
25 granted / 36 resolved
+1.4% vs TC avg
Strong +23% interview lift
Without
With
+23.2%
Interview Lift
resolved cases with interview
Typical timeline
2y 6m
Avg Prosecution
33 currently pending
Career history
69
Total Applications
across all art units

Statute-Specific Performance

§103
62.2%
+22.2% vs TC avg
§102
26.5%
-13.5% vs TC avg
§112
11.3%
-28.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 36 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 filed 1/20/26 have been fully considered but they are not persuasive. Applicant asserts that: “But Applicant contends that Chen does not disclose or render obvious that the "first and second arms define a winding channel for locating a winding relative to the stator core, and the winding channel comprises a generally trapezoidal cross-sectional shape." As illustrated below, Chen teaches a stator core that is most accurately described as rectangular in shape (see left hand side annotated example). Or if the perimeter of the stator core is interpreted more specifically, the shape is some form of hexagonal shape. Applicant contends, that in either interpretation, the stator core of Chen is not generally trapezoidal in shape as the claims recite.” The examiner, however, disagrees. Chen discloses the back and the first and second arms define a winding channel for locating a winding relative to the stator core (125; Fig. 2 of Chen), and the winding channel comprises a generally trapezoidal cross-sectional shape (Fig. 2 of Chen). PNG media_image1.png 486 425 media_image1.png Greyscale 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1-2, 4, and 20-21 are rejected under 35 U.S.C. 103 as being unpatentable over Chen (CN 211630057), and in view of Yu (GB 2577546). As to claim 1, Chen discloses a stator core, the stator core comprising a back, and first and second arms extending from the back, each of the first and second arms comprising a first portion extending substantially orthogonally relative to the back, and a second portion obliquely angled relative to the first portion, wherein the back and the first and second arms define a winding channel for locating a winding relative to the stator core (125; Fig. 2), and the winding channel comprises a generally trapezoidal cross-sectional shape (Fig. 2). PNG media_image2.png 479 542 media_image2.png Greyscale PNG media_image1.png 486 425 media_image1.png Greyscale Chen fails to disclose a brushless permanent magnet motor. Yu, however, discloses a brushless permanent magnet motor (“The permanent magnet motor 100 is a single-phase brushless permanent magnet motor”). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to provide the stator core of Chen with a brushless permanent magnet motor, as disclosed by Yu, to achieve higher levels of efficiency and to reduce the size of the motor. As to claim 2, the combination of Chen and Yu discloses the stator core as claimed in Claim 1, wherein the second portions of the first and second arms are angled toward one another (Fig. 6 of Chen). PNG media_image3.png 371 541 media_image3.png Greyscale As to claim 4, the combination of Chen and Yu discloses the stator core as claimed in Claim 1, wherein the second portions of the first and second arms are angled (Fig. 2 of Chen). Chen fails to disclose around 20 to 40 degrees relative to the respective first portions of the first and second arms. However, those skilled in the art would recognize that the above limitations do not involve any inventive concept. They would merely depend on how one decides to design the angle of the first and second arms. Furthermore, the instant specification fails to disclose any unexpected results obtained from the fact that the second portions of the first and second arms are angled around 20 to 40 degrees relative to the respective first portions of the first and second arms. Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modify the stator core of Chen, such that the second portions of the first and second arms are angled around 20 to 40 degrees relative to the respective first portions of the first and second arms, in order to reduce the volume and make the structure compact. As to claim 20, the combination of Chen and Yu discloses a brushless permanent magnet motor comprising the stator core as claimed in Claim 1 (Yu states, “The permanent magnet motor 100 is a single-phase brushless permanent magnet motor”). As to claim 21, the combination of Chen and Yu discloses a vacuum cleaner (Fig. 13 of Yu) comprising the brushless permanent magnet motor as claimed in Claim 20. PNG media_image4.png 505 287 media_image4.png Greyscale Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Chen, Yu, and in view of Weng (CN 110556997) As to claim 5, the combination of Chen and Yu discloses the stator core as claimed in Claim 1. Chen fails to disclose a length of each second portion is in the region of 1.5 to 2.5 times a length of the respective first portion. Weng, however, discloses a length of each second portion is larger than the length of the first portion (Fig. 7b). PNG media_image5.png 394 380 media_image5.png Greyscale Weng fails to disclose in the region of 1.5 to 2.5 times a length of the respective first portion. However, those skilled in the art would recognize that the above limitations do not involve any inventive concept. They would merely depend on how one decides how much longer the second portion is than the first portion. Furthermore, the instant specification fails to disclose any unexpected results obtained from the fact a length of each second portion is in the region of 1.5 to 2.5 times a length of the respective first portion. Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modify the stator core of Chen, such that a length of each second portion is in the region of 1.5 to 2.5 times a length of the respective first portion, in order to optimize space for the windings. Claims 6-10 are rejected under 35 U.S.C. 103 as being unpatentable over Chen, Yu, and in view of Horiuchi (US 2020/0204015). As to claim 6, the combination of Chen and Yu discloses the stator core as claimed in Claim 1, wherein each second portion comprises a respective pole face (Fig. 2 of Chen). PNG media_image6.png 272 452 media_image6.png Greyscale Chen fails to disclose the pole faces of the first and second arms are asymmetric. Horiuchi, however, discloses the pole faces of the first and second arms are asymmetric (Fig. 2). PNG media_image7.png 419 483 media_image7.png Greyscale Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to provide the stator core of Chen with the pole faces of the first and second arms are asymmetric, as disclosed by Horiuchi, to achieve higher levels of torque (Para 0057). As to claim 7, the combination of Chen, Yu, and Horiuchi discloses the stator core as claimed in Claim 6, wherein the pole faces are curved (Fig. 2 of Chen), and a center of curvature of the pole face of the first arm is different to a center of curvature of the pole face of the second arm (Fig. 2 of Chen). PNG media_image8.png 361 413 media_image8.png Greyscale As to claim 8, the combination of Chen, Yu, and Horiuchi discloses the stator core as claimed in Claim 6, wherein the pole face of the first arm is a different shape to the pole face of the second arm (Fig. 2 of Horiuchi), the pole face of the first arm is asymmetric about a center line of the pole face of the first arm (Fig. 2 of Chen), and the pole face of the second arm is asymmetric about a center line of the pole face of the second arm (Fig. 2 of Chen). PNG media_image9.png 758 548 media_image9.png Greyscale As to claim 9, the combination of Chen, Yu, and Horiuchi discloses the stator core as claimed in Claim 6, wherein the pole faces of the first and second arms are spaced apart to define a slot gap (Fig. 2 of Chen). PNG media_image10.png 268 327 media_image10.png Greyscale Chen fails to disclose a ratio of a combined width of the pole faces to the width of the slot gap is in the region of 3:1 to 7:1. However, those skilled in the art would recognize that the above limitations do not involve any inventive concept. They would merely depend on how large one decides to design the slot gap. Furthermore, the instant specification fails to disclose any unexpected results obtained from the fact that a ratio of a combined width of the pole faces to the width of the slot gap is in the region of 3:1 to 7:1. Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modify the stator core of Chen, such that a ratio of a combined width of the pole faces to the width of the slot gap is in the region of 3:1 to 7:1, in order to optimize space for the windings. As to claim 10, the combination of Chen, Yu, and Horiuchi discloses the stator core as claimed in Claim 9, a distance from the pole face of the first arm to a centre line of the slot gap and a distance from the pole face of the second arm to the centre line of the slot gap (Fig. 2 of Chen). PNG media_image11.png 266 453 media_image11.png Greyscale Chen fails to disclose a distance from the pole face of the first arm to a centre line of the slot gap is different to a distance from the pole face of the second arm to the centre line of the slot gap. However, those skilled in the art would recognize that the above limitations do not involve any inventive concept. They would merely depend on how one decides to design the pole faces of the arms and their distances from the centre line of the slot gap. Furthermore, the instant specification fails to disclose any unexpected results obtained from the fact that a distance from the pole face of the first arm to a centre line of the slot gap is different to a distance from the pole face of the second arm to the centre line of the slot gap. Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modify the stator core of Chen, such that a distance from the pole face of the first arm to a centre line of the slot gap is different to a distance from the pole face of the second arm to the centre line of the slot gap, in optimize space for the windings. Claims 11-12 are rejected under 35 U.S.C. 103 as being unpatentable over Chen, Yu, and in view of Gary (GB 2500580). As to claim 11, the combination of Chen and Yu discloses the stator core as claimed in Claim 1. Chen fails to disclose the stator core comprises a plurality of laminations connected together, and the second portions of the first and second arms comprise protrusions for facilitating connection of the plurality of laminations. Gary, however, discloses the stator core comprises a plurality of laminations connected together, and the second portions of the first and second arms comprise protrusions for facilitating connection of the plurality of laminations (Fig. 1). PNG media_image12.png 626 438 media_image12.png Greyscale Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to provide the stator core of Chen with the stator core comprises a plurality of laminations connected together, and the second portions of the first and second arms comprise protrusions for facilitating connection of the plurality of laminations, as disclosed by Gary, to properly secure the lamination together. As to claim 12, the combination of Chen, Yu, and Gary discloses the stator core as claimed in Claim 11, wherein the protrusions are located on outwardly facing surfaces of the second portions (Fig. 1). PNG media_image13.png 638 431 media_image13.png Greyscale Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Chen, Yu, and in view of Dymond (WO 2017098202). As to claim 13, the combination of Chen and Yu discloses the stator core as claimed in Claim 1. Chen fails to disclose wherein the back is asymmetric about a centre line of the stator core. Dymond, however, discloses the back is asymmetric about a centre line of the stator core (Fig. 5). PNG media_image14.png 368 575 media_image14.png Greyscale Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to provide the stator core of Chen with the back is asymmetric about a centre line of the stator core, as disclosed by Dymond, in order to reduce core losses leading to better efficiency. Claims 14-15 are rejected under 35 U.S.C. 103 as being unpatentable over Chen, Yu, and in view of Thomas (GB 2571553). As to claim 14, the combination of Chen and Yu discloses a stator core as claimed in Claim 1. Chen fails to disclose the stator core sub-assembly, and a bobbin overmoulded to the stator core. Thomas, however, discloses the stator core sub-assembly (Fig. 5), and a bobbin (54, 56; Fig. 3) overmoulded to the stator core. PNG media_image15.png 628 407 media_image15.png Greyscale Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to provide the stator core of Chen with the stator core sub-assembly, and a bobbin overmoulded to the stator core, as disclosed by Thomas, to properly insulate the stator core. As to claim 15, the combination of Chen, Yu, and Thomas discloses the stator core sub-assembly as claimed in Claim 14, wherein the bobbin comprises a winding guide for guiding a winding relative to the bobbin (44; Fig. 9 of Yu), the winding guide located within a channel on a portion of the bobbin that overlies the back of the stator core (Fig. 9 of Yu). PNG media_image16.png 525 303 media_image16.png Greyscale Claims 16-19 are rejected under 35 U.S.C. 103 as being unpatentable over Chen, Yu, Thomas, and in view of Kim (US 20140009022). As to claim 16, the combination of Chen, Yu, and Thomas discloses the stator core sub-assembly as claimed in Claim 14. Chen fails to disclose wherein the bobbin comprises a connection portion for connecting to a further bobbin of a further stator core sub-assembly. Kim, however, discloses the bobbin comprises a connection portion (45; Fig. 6) for connecting to a further bobbin of a further stator core sub-assembly (Para 0082). PNG media_image17.png 290 259 media_image17.png Greyscale Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to provide the subassembly of Chen with the bobbin comprises a connection portion for connecting to a further bobbin of a further stator core sub-assembly, as disclosed by Kim, in order to properly secure the bobbins together. As to claim 17, the combination of Chen, Yu, and Thomas discloses the stator core sub-assembly as claimed in claim 14, wherein the stator core sub-assembly comprises a winding wound about the bobbin such that the winding is wound about the back of the stator core (Fig. 5 of Thomas), and the winding defines a generally trapezoidal cross-sectional shape on an inner surface of the back (Fig. 2 of Chen). PNG media_image18.png 645 422 media_image18.png Greyscale As to claim 18, the combination of Chen, Yu, and Thomas discloses the stator core sub-assembly as claimed in claim 17, wherein the winding defines a different cross-sectional shape on an outer surface of the back (Fig. 9 of Yu). PNG media_image19.png 449 268 media_image19.png Greyscale As to claim 19, the combination of Chen, Yu, and Thomas discloses a stator assembly (Fig. 5 of Thomas) comprising a plurality of the stator core sub-assemblies as claimed in Claim 14. PNG media_image20.png 355 407 media_image20.png Greyscale Conclusion THIS ACTION IS MADE FINAL. 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 ETHAN N VO whose telephone number is (571)270-7593. The examiner can normally be reached Mon-Fri 8:30am - 5pm. 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, Christopher M Koehler can be reached on 571 272 3560. 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. /ETHAN NGUYEN VO/ Examiner, Art Unit 2834 /CHRISTOPHER M KOEHLER/Supervisory Patent Examiner, Art Unit 2834
Read full office action

Prosecution Timeline

Jan 11, 2024
Application Filed
Oct 10, 2025
Non-Final Rejection — §103
Jan 20, 2026
Response Filed
Feb 09, 2026
Final Rejection — §103 (current)

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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
69%
Grant Probability
93%
With Interview (+23.2%)
2y 6m
Median Time to Grant
Moderate
PTA Risk
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