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 .
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 03/02/2026 is/are in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement are being considered by the examiner.
Response to Arguments
Applicant's arguments filed 12/15/2025 have been fully considered. Applicant argues that the combination of the cited references of Liu and Mihara fail to disclose or suggest claim 1 primarily due to the differences in the cooling targets and cooling methods of the cited references.
In response to applicant’s argument that there is no teaching, suggestion, or motivation to combine the references, the examiner recognizes that obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
In this case, Liu teaches a stator including a back iron having coolant passages extending axially to an end face. Mihara teaches arranging coolant passages with two-fold symmetry about a central axis. Although Mihara describes this symmetry in the context of a gravity-dependent cooling structure, Mihara nonetheless expressly teaches the structural concept of arranging coolant passages with two-fold symmetry about a central axis.
The claimed limitation is directed solely to the structural configuration at the first end face, namely, that the plurality of coolant passages has two-fold symmetry and does not have four-fold symmetry. The limitation does not address whether cooling relies on gravity or jet impingement. Furthermore, symmetry is a structural property that exists independent of whether coolant is gravity-fed or sprayed. A coolant passage arrangement that is two-fold symmetric retains that property regardless of the manner in which coolant is supplied.
It would have been obvious to a person of ordinary skill in the art to apply the known two-fold symmetric arrangement of coolant passages taught by Mihara to the stator back iron of Liu as a predictable design variation. Selection of a known symmetric configuration represents no more than routine optimization of passage layout for purposes such as flow balance, packaging constraints, thermal management, or manufacturability. Substituting one known symmetric arrangement for another would have yielded predictable results and does not alter the fundamental operation of the cooling system. Accordingly, the combination amounts to the predictable use of a known structural arrangement in a similar cooling environment and would have been obvious. Therefore, Applicant’s arguments have not been found persuasive.
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.
Claim(s) 1-14 are rejected under 35 U.S.C. 103 as being unpatentable over Liu (CN 112615445 A) in view of Mihara (US 20220255403 A1).
Claim 1
Liu teaches: A stator for an electric motor (100), comprising: a back iron (20) having a cylindrical shape and extending along an axial direction;
a plurality of teeth (teeth between clots 23) provided on an inner circumferential surface of the back iron (20);
and a stator coil (33) provided on the plurality of teeth (teeth between slots 23), wherein the back iron (20) comprises a plurality of coolant passages (101) that is arranged in a circumferential direction in circumferential regions of the back iron (20), the plurality of coolant passages (101) extending along the axial direction to a first end face of the back iron (20), the plurality of coolant passages (101) includes a coolant passage located in an uppermost portion (portion on upper axial half) of the back iron (20) in a vertical direction and a coolant passage located in a lowermost portion (portion on bottom axial half) of the back iron (20) in the vertical direction, and at the first end face of the back iron (20);
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Liu is silent however to:
an arrangement of the plurality of coolant passages has two-fold symmetry and does not have four-fold symmetry.
Mihara conversely teaches a stator winding cooling structure (50), comprised of a plurality of coolant passages (54) that may be arranged at angular intervals (θ) providing grouped/no-hole sectors. The divisions of the angular intervals (θ) provided mirrored nozzle inclination at diametrically opposing sides of the stator winding cooling structure (50) to provide at least a two-fold symmetry for the two circumferential regions (R1, R2) indicated below.
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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 Liu’s motor such that an arrangement of the plurality of coolant passages has two-fold symmetry and does not have four-fold symmetry. Having the flexibility to position the coolant passages at desired angular intervals would be advantageous in providing uniform thermal balance and concentrating the holes into two opposed sectors allows each jet to have higher velocity/penetration to cool the stator coil, thus improving the overall cooling efficiency of the coolant passages.
Claim 2/1
Liu as modified by Mihara teaches: The stator according to claim 1, wherein the plurality of coolant passages (101) comprises: a plurality of first coolant passages (in top half of stator as illustrated in Fig. 5) disposed in a first circumferential region (R1; Mihara) of the back iron (20); a plurality of second coolant passages (in bottom half of stator as illustrated in Fig. 5) disposed in a second circumferential region (R2; Mihara) of the back iron (20), and the first circumferential region (R1; Mihara) includes the uppermost portion (portion on upper axial half) of the back iron (20) in the vertical direction and the second circumferential region includes the lowermost portion (portion on bottom axial half) of the back iron (20) in the vertical direction, when viewed in a radial cross-section of the back iron (20).
Claim 3/2/1
Liu as modified by Mihara teaches: The stator according to claim 2, wherein the uppermost portion (portion on upper axial half) is located at a center (region indicated may be considered as center) of the first circumferential region (R1) and the lowermost portion (portion on bottom axial half) is located in a center (region indicated may be considered as center) of the second circumferential region (R2).
Claim 4/2/1
Liu as modified by Mihara teaches: The stator according to claim 2, wherein each of the first circumferential region (R1) and the second circumferential (R2) is a region of 120 degrees or less (θ is less than 90 degrees as illustrated in Fig. 4) in the circumferential direction.
Claim 5/4/2/1
Liu as modified by Mihara teaches: The stator according to claim 4, wherein each of the first circumferential region (R1) and the second circumferential region (R2) is a region defined by θ in the circumferential direction.
Liu as modified by Mihara does not explicitly disclose a region of 45 degrees or less in the circumferential direction. Mihara does however illustrate θ as having a range less than 90 degrees. And considering θ is a variable that may be adjusted accordingly based on design need, it would have been obvious to try by one of ordinary skill in the art before the effective filing date of the claimed invention to have θ encompass a region of 45 degrees or less in the circumferential direction. Please see MPEP 2131.03; Titanium Metals Corp. v. Banner, 778 F.2d 775, 227 USPQ 773 (Fed. Cir. 1985) (citing In re Petering, 301 F.2d 676, 682, 133 USPQ 275, 280 (CCPA 1962)) (emphasis in original) (Claims to titanium (Ti) alloy with 0.6-0.9% nickel (Ni) and 0.2-0.4% molybdenum (Mo) were held anticipated by a graph in a Russian article on Ti-Mo-Ni alloys because the graph contained an actual data point corresponding to a Ti alloy containing 0.25% Mo and 0.75% Ni and this composition was within the claimed range of compositions.). "If the prior art discloses a point within the claimed range, the prior art anticipates the claim." UCB, Inc. v. Actavis Labs. UT, Inc., 65 F.4th 679, 687, 2023 USPQ2d 448 (Fed. Cir. 2023).
Claim 6/2/1
Liu as modified by Mihara teaches: The stator according to claim 2, wherein none of the plurality of coolant passages (101) is disposed in a third circumferential region (any small angular section adjacent to R1/R2 not comprising 54 may be considered) and a fourth circumferential region of the back iron (20), each of the third circumferential region and the fourth circumferential region (any additional small angular section adjacent to R1/R2 not comprising 54 may be considered) is adjacent to the first circumferential region (R1) and the second circumferential region (R2).
Claim 7/1
Liu as modified by Mihara teaches: The stator according to claim 1, wherein the plurality of coolant passages (101) is at least partially formed of a plurality of through holes (see Fig. 5) defined in the back iron (20).
Claim 8/1
Liu as modified by Mihara teaches: The stator according to claim 1, wherein the back iron (20) comprises an annular coolant passage (13) extending in the circumferential direction and connected to each of the plurality of coolant passages (101).
Claim 9/8/1
Liu as modified by Mihara teaches: The stator according to claim 8, wherein the annular coolant passage (13) is formed of a groove defined in an outer circumferential surface of the back iron (20).
Claim 10/8/1
Liu as modified by Mihara teaches: The stator according to claim 8, further comprising a casing surrounding an outer circumferential surface of the back iron (20), wherein the casing (10) comprises a coolant supply hole (11) connected to the annular coolant passage (13), the coolant supply hole (11) located at an intermediate position of the annular coolant passage (13) in the vertical direction.
Claim 11/1
Liu as modified by Mihara teaches: The stator according to claim 1, further comprising a first annular member (416) disposed on the first end face (surface of stator core 20 near concave part 17) of the back iron (20), wherein the first annular member (416) comprises a plurality of first coolant injection holes (411a) that are directed toward a first coil end (31) of the stator coil (33) protruding from the first end face (surface of stator core 20 near concave part 17).
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Claim 12/1
Liu as modified by Mihara teaches: The stator according to claim 1, wherein the plurality of coolant passages (101) extends along the axial direction to a second end face (surface of stator core 20 near concave part 427) of the back iron (20) located opposite the first end face (surface of stator core 20 near concave part 17).
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Claim 13/12/1
Liu as modified by Mihara teaches: The stator according to claim 12, further comprising a second annular member (426) disposed on the second end face (surface of stator core 20 near concave part 427) of the back iron (20), wherein the second annular member (426) comprises a plurality of second coolant injection holes (421a) that are directed toward a second coil end (32) of the stator coil (33) protruding from the second end face (surface of stator core 20 near concave part 427).
Claim 14/1
Liu as modified by Mihara teaches: An electric motor (100) comprising: the stator (stator of core 20) according to claim 1; and a rotor (rotor, Background, para. 2) disposed within the stator (stator of core 20).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Leonid (US2018076694A1) conversely teaches a plurality of axially extending cooling channels (90), and annular coolant passages (114) embedded in a stator core as illustrated below.
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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 AHMED F SECK whose telephone number is (571)272-4638. The examiner can normally be reached Monday - Friday 7:30 am - 4:30 pm.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Christopher Koehler can be reached at (571) 272-3560. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/AHMED F SECK/Examiner, Art Unit 2834
/CHRISTOPHER M KOEHLER/Supervisory Patent Examiner, Art Unit 2834