Prosecution Insights
Last updated: April 19, 2026
Application No. 18/754,952

HEAT EXCHANGER CORE LAYER DESIGN

Non-Final OA §102§103
Filed
Jun 26, 2024
Examiner
BHATTACHAN, BIGYAN NMN
Art Unit
3763
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Hamilton Sundstrand Corporation
OA Round
1 (Non-Final)
Grant Probability
Favorable
1-2
OA Rounds
3y 2m
To Grant

Examiner Intelligence

Grants only 0% of cases
0%
Career Allow Rate
0 granted / 0 resolved
-70.0% vs TC avg
Minimal +0% lift
Without
With
+0.0%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
7 currently pending
Career history
7
Total Applications
across all art units

Statute-Specific Performance

§103
68.8%
+28.8% vs TC avg
§102
18.8%
-21.2% vs TC avg
§112
12.5%
-27.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 0 resolved cases

Office Action

§102 §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 . Priority Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. Information Disclosure Statement The information disclosure statement (IDS) submitted on 26 June, is being considered by the examiner. Claim Rejections - 35 USC § 102 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention. Claim(s) 1 – 3, is/ are rejected under 35 U.S.C. 102 (a) (2) as being anticipated by HORIUCHI et al. (US 2004/0050531 A1 – published on March 18th, 2004). As to Claim 1, HORIUCHI discloses a heat exchanger core layer comprising: a first end (14); a second end (6c) opposite the first end; a first side (6a) extending between the first end and the second end; a second side (6b), extending between the first end and extending towards the second end between the first side and the second side; wherein: a first flow region is formed between the first side and the divider (4); a second flow region is defined between the divider and the second side and a turnaround region (6c) is defined adjacent the second end between the first flow region and the second flow region; the layer has a plurality of first flow channels in the first flow region for directing a fluid flow, in use, in a first direction from the first end to the turnaround region (See Annotated Figure Below), and a plurality of second flow channels in the second flow region for directing a fluid flow, in use, in a second direction opposite the first direction, from the turnaround region back to the first end (See Annotated Figure Below), and wherein channels closer to the divider, in each of the first flow region and the second flow region are narrower than channels closer to the first and second sides (See Annotated Figure Below). As to Claim 2, HORIUCHI discloses a heat exchanger core layer as claimed in claim 1, further comprising: a plurality of turnaround flow channels in the turnaround region for directing fluid flow, in use, from the first fluid flow region to the second fluid flow region. (See Annotated Figure Below which shows plurality of turnaround flow channels in the turnaround region for directing fluid flow from first flow region to the second flow region). As to Claim 3, HORIUCHI discloses a heat exchanger core layer as claimed in claim 2, further comprising: turnaround vanes (9b) providing a transition from the turnaround flow channels and the first flow channels and the second flow channels. (See Annotated Figure Below which shows turnaround vanes that provides a transition from the turnaround flow channels and the first flow channels and the second flow channels). [AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: textbox (Second Side )][AltContent: arrow][AltContent: textbox (Divider)][AltContent: textbox (Channels Closer to the Divider are Narrower)][AltContent: arrow][AltContent: textbox (First Side)][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: textbox (Turnaround Region )][AltContent: textbox (Turnaround Vanes)][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: textbox (Turnaround Channels)][AltContent: textbox (Channels Closer to the First Side and the Second Side are Wider)][AltContent: arrow][AltContent: textbox (Second End)][AltContent: arrow][AltContent: textbox (Second Flow Channels)][AltContent: textbox (First Flow Channels)][AltContent: textbox (Second Flow Region )][AltContent: textbox (First Flow Region )][AltContent: textbox (First End)] PNG media_image1.png 707 270 media_image1.png Greyscale Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. 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 4, is rejected under 35 U.S.C. 103 as being unpatentable over HORIUCHI et al. (US 2004/0050531 A1 – published on March 18th, 2004), in view of PERSSON et al. (US 2014/0008046 A1 – published January 9, 2014). As to Claim 4, HORIUCHI discloses a heat exchanger core layer as claimed in claim1. However, HORIUCHI does not disclose that the first and second sides are shorter than the first and second ends. PERSSON, however, teaches the first and second sides are shorter than the first and second ends and that this change in aspect ratio results in the location of the inlet and outlet to be arranged accordingly (Pages 14-15, Paragraph 36 and 37, See Annotated Figure Below). It is known in general that in mechanical designs, changing the aspect ratio is desirable based on requirements for component spacing and housing. Therefore, when there are a finite number of identified, predictable solutions, i.e. to change the aspect ratio of a design, a person of ordinary skill has a good reason to pursue the known options within his or her technical grasp. If this leads to the anticipated success, i.e. improved design, it is likely the product is not of innovation but of ordinary skill and common sense. In that instance, the fact that a combination was obvious to try might show it was obvious under 35 U.S.C. 103(KSR Int’ l Co. v. Teleflex Incl, 127 S. Ct. 1727, 1742, 82 USPQ2d 1385, 1396 (2007)). Therefore, it would have been obvious to one of ordinary skill in the art, at the time of effective filing date of the claimed invention, to have modified HORIUCHI, to change the aspect ratio and make the width greater than the length, as it has been held obvious to try when choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success. See MPEP § 2143 – (I) (E). In the instant case, PERSSON teaches such aspect ratio is suitable for use in heat exchangers having multiple pass design. [AltContent: arrow][AltContent: arrow][AltContent: textbox (Second End)][AltContent: textbox (First and Second Sides are shorter than First and Second Ends)][AltContent: arrow][AltContent: textbox (First End)][AltContent: arrow][AltContent: textbox (First Side)][AltContent: textbox (Second Side)] PNG media_image2.png 416 651 media_image2.png Greyscale Claim(s) 5-6, is/ are rejected under 35 U.S.C. 103 as being unpatentable over HORIUCHI et al. (US 2004/0050531 A1 – published on March 18th, 2004), in view of RUBALEWSKI (EP 4063779 A1 – published September 9, 2022). As to Claim 5, HORIUCHI discloses a heat exchanger core layer as claimed in Claim 5, wherein there are the first flow channels and second flow channels. However, HORIUCHI does not disclose that the flow channels are defined by rows of pins. RUBALEWSKI, however, teaches that the flow channels are defined by rows of pins (Page 2, Column 1, Paragraph 2-4, lines 6-29, See Annotated Figure Below). In Additive Manufacturing (AM) one type of heat exchanger design is pin-fin design, the type of flow channels defined by pins provides improved heat transfer rate because they can be designed in any shapes to increase the surface area of the contact and also encourage types of flows such as laminar or turbulent in the direction of the flow (Paragraphs 5-9). Therefore, when there are a finite number of identified, predictable solutions, i.e. to define the flow channels by rows of pins, a person of ordinary skill has a good reason to pursue the known options within his or her technical grasp. If this leads to the anticipated success, i.e. improved heat transfer efficiency, it is likely the product is not of innovation but of ordinary skill and common sense. In that instance, the fact that a combination was obvious to try might show it was obvious under 35 U.S.C. 103(KSR Int’ l Co. v. Teleflex Incl, 127 S. Ct. 1727, 1742, 82 USPQ2d 1385, 1396 (2007)). Therefore, it would have been obvious to one of ordinary skill in the art, at the time of effective filing date of the claimed invention, to modify HORIUCHI, by the teachings of RUBALEWSKI to define the flow channels by rows of pins, since choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success, is within the abilities of one having ordinary skill. See MPEP § 2143 – (I) (E). [AltContent: rect][AltContent: rect][AltContent: rect][AltContent: rect][AltContent: rect][AltContent: rect][AltContent: textbox (First flow channels and Second flow channels defined by Rows of Pins )][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: arrow] PNG media_image3.png 629 452 media_image3.png Greyscale As to Claim 6, HIROUCHI discloses a heat exchanger core layer as claimed in claim 5, However, HIROUCHI does not disclose that the pins taper from a wider end to a narrower end in the fluid flow direction. RUBALEWSKI, however, teaches that the pins taper from a wider end to a narrower end in the fluid flow direction (Page 2, Paragraphs 5-12 and 67-69, See Annotated Figure Below). It is known that in heat exchanger designs, the shape of the pins may be selected to direct fluid flow in a desired manner as some shapes may help induce turbulence in a fluid flowing past the pin, while other shapes may encourage laminar flow. Therefore, when there are a finite number of identified, predictable solutions, i.e. to have pins taper from a wider end to a narrower end in the fluid flow direction, a person of ordinary skill has a good reason to pursue the known options within his or her technical grasp. If this leads to the anticipated success, i.e. improved heat transfer efficiency, it is likely the product is not of innovation but of ordinary skill and common sense. In that instance, the fact that a combination was obvious to try might show it was obvious under 35 U.S.C. 103(KSR Int’ l Co. v. Teleflex Incl, 127 S. Ct. 1727, 1742, 82 USPQ2d 1385, 1396 (2007)). Therefore, it would have been obvious to one of ordinary skill in the art, at the time of effective filing date of the claimed invention, to modify HORIUCHI, to have pins taper from a wider end to a narrower end in the fluid flow direction, as it has been held obvious to try when choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success. See MPEP § 2143 – (I) (E). In the instant case, RUBALEWSKI teaches that pins that taper from a wider end to a narrower end in the fluid flow direction is suitable for use in improving heat exchanger’s efficiency. [AltContent: arrow][AltContent: arrow][AltContent: textbox (Pins taper from a wider end to a narrower end in the fluid flow direction)] PNG media_image4.png 426 491 media_image4.png Greyscale Claim(s) 7-8, is/ are rejected under 35 U.S.C. 103 as being unpatentable over HORIUCHI et al. (US 2004/0050531 A1 – published on March 18th, 2004), in view of MAYBERRY et al. (US 2019/0373772 A1 – published December 5, 2019). As to Claim 7, HIROUCHI discloses a heat exchanger core layer as claimed in claim 5, However, HIROUCHI does not disclose that the width of the fluid flow channels is varied by varying the spacing of the pins in the direction perpendicular to the fluid flow direction. MAYBERRY, however teaches that the width of the fluid flow channels can be varied by varying the spacing of the pins in the direction perpendicular to the fluid flow direction, it teaches that the pins are arranged such that their spacing varies along the structure, and the pins define the flow paths for fluid flowing through the channel (Page 7, Paragraphs 4,7-9, See Annotated Figure Below). It further teaches that the spacing between pins gradually decreases or otherwise varies to control fluid flow and thermal performance (Page 8, Paragraphs 17-20). Because the pins define the boundaries of the flow paths within the cooling channel, varying the spacing between the pins necessarily varies the width of the fluid flow channels formed between adjacent pins. Accordingly, pin spacing would have been considered a result effective variable by one having ordinary skill in the art before the effective filing date of the invention. Modifying the spacing between pins to vary the width of fluid flow channels would have been an obvious matter of routine optimization to a person of ordinary skill in the art seeking to control fluid flow characteristics and heat transfer performance. [AltContent: textbox (Varying widths using spacing of the pins in the direction perpendicular to the flow direction )][AltContent: arrow][AltContent: arrow][AltContent: arrow][AltContent: rect][AltContent: rect][AltContent: rect] PNG media_image5.png 222 655 media_image5.png Greyscale As to Claim 8, HIROUCHI discloses a heat exchanger core layer as claimed in claim 5, However, HIROUCHI does not disclose that the width of the fluid flow channels is varied by varying the size of the pins in the direction perpendicular to the fluid flow direction. MAYBERRY, however teaches that the width of the fluid flow channels can be varied by varying the size of the pins in the direction perpendicular to the fluid flow direction, The size of the pin shaped fins varies along the length of the heat dissipating surface, including embodiments in which the diameter of the pins increases or decreases (Page 7, Paragraphs 9, See Annotated Figure Below). Because the pin shaped fins define the boundaries of the flow paths within the cooling channel, varying the size of the pins necessarily varies the effective width of the fluid flow channels formed between adjacent pins. Accordingly, varying the width based on varying pin size would have been considered a result effective variable by one having ordinary skill in the art before the effective filing date of the invention. Modifying the size of the pins to vary the width of fluid flow channels would have been an obvious matter of routine optimization to a person of ordinary skill in the art seeking to control fluid flow characteristics and heat transfer performance. [AltContent: textbox (Varying widths based on varying size of the pins in the direction perpendicular to the flow)] [AltContent: arrow][AltContent: arrow][AltContent: arrow] PNG media_image5.png 222 655 media_image5.png Greyscale Claim(s) 9-11, is/ are rejected under 35 U.S.C. 103 as being unpatentable over HORIUCHI et al. (US 2004/0050531 A1 – published on March 18th, 2004), in view of RUBALEWSKI (EP 4063779 A1 – published September 9, 2022). As to Claim 9, HIROUCHI discloses a heat exchanger core layer as claimed in claim 1, However, HIROUCHI does not disclose the forming of heat exchanger core layer by additive manufacturing. RUBALEWSKI, however, teaches the forming of heat exchanger core layer by additive manufacturing (Page 3, Paragraphs 26-33). Additive Manufacturing can help improve accuracy in placement and orientation of the pins within the heat exchanger and it is a well-known manufacturing technique. Therefore, it would have been obvious to one of ordinary skill in the art, at the time of effective filing date of the claimed invention, to modify HORIUCHI, by the teachings of RUBALEWSKI to have the forming of heat exchanger core layer by additive manufacturing. As to Claim 10, HIROUCHI discloses a heat exchanger core, However, HIROUCHI does not disclose a heat exchanger core comprising a plurality of heat exchanger core layers as claimed in claim 1 stacked together wherein the fluid flow channels are defined therebetween. RUBALEWSKI, however, teaches a heat exchanger core comprising a plurality of heat exchanger core layers (30 (a-n)) as claimed in claim 1 stacked together wherein the fluid flow channels are defined therebetween (Paragraphs 30-31, 36, 64, See Annotated Figure Below). Therefore, it would have been obvious to one of ordinary skill in the art, at the time of effective filing date of the claimed invention, to modify HORIUCHI, by the teachings of RUBALEWSKI to have the heat exchanger core comprising a plurality of heat exchanger core layers as claimed in claim 1 stacked together wherein the fluid flow channels are defined therebetween. [AltContent: arrow][AltContent: arrow][AltContent: textbox (Stacked Heat exchange core layers (30))] PNG media_image6.png 546 668 media_image6.png Greyscale As to Claim 11, HIROUCHI discloses a heat exchanger, However, HIROUCHI does not disclose that the heat exchanger comprises a heat exchanger core as claimed in claim 10. RUBALEWSKI, however, teaches the heat exchanger comprises a heat exchanger core as claimed in claim 10 (Page 2, Paragraph 1). Therefore, it would have been obvious to one of ordinary skill in the art, at the time of effective filing date of the claimed invention, to modify HORIUCHI, by the teachings of RUBALEWSKI to have the heat exchanger comprising a heat exchanger core as claimed in claim 10. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to BIGYAN BHATTACHAN whose telephone number is (571)272-8767. The examiner can normally be reached Monday - Friday 7:30 AM - 5 PM. 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, Len Tran can be reached at (571) 272-1184. 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. /BIGYAN BHATTACHAN/ EXAMINER, ART UNIT 3763 /LEN TRAN/Supervisory Patent Examiner, Art Unit 3763
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Prosecution Timeline

Jun 26, 2024
Application Filed
Feb 02, 2026
Non-Final Rejection — §102, §103 (current)

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Prosecution Projections

1-2
Expected OA Rounds
Grant Probability
3y 2m
Median Time to Grant
Low
PTA Risk
Based on 0 resolved cases by this examiner. Grant probability derived from career allow rate.

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