Prosecution Insights
Last updated: April 19, 2026
Application No. 19/063,834

SEALS AND FLOW RESTRICTORS FOR ROTARY MACHINES

Non-Final OA §102§103
Filed
Feb 26, 2025
Examiner
KONERU, LAKSHMI S
Art Unit
3675
Tech Center
3600 — Transportation & Electronic Commerce
Assignee
Howden Group Limited
OA Round
1 (Non-Final)
62%
Grant Probability
Moderate
1-2
OA Rounds
3y 1m
To Grant
80%
With Interview

Examiner Intelligence

Grants 62% of resolved cases
62%
Career Allow Rate
298 granted / 481 resolved
+10.0% vs TC avg
Strong +18% interview lift
Without
With
+17.8%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
36 currently pending
Career history
517
Total Applications
across all art units

Statute-Specific Performance

§103
59.1%
+19.1% vs TC avg
§102
26.9%
-13.1% vs TC avg
§112
12.5%
-27.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 481 resolved cases

Office Action

§102 §103
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 . 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)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claims 1 – 7, 9 – 13 and 17 - 20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Reeves et al. (U.S. Patent # 4940080). Regarding Claim 1, Reeves discloses a rotary machine (figs 1, 2 and 3), comprising : a rotor (shaft 16) with a plurality of plates defining openings therebetween (openings between plurality of 34) ; a housing (14) enclosing the rotor (16); and a flow restrictor (36) comprising : a body (72) attached to a plate (34) of the plurality of plates of the rotor (plurality of 34) and extending from the rotor toward the housing (36 extends from 16 towards 14); and a plurality of extensions (54, 56) extending from the body toward the housing (54, 56 extend from 36 toward 14) to form a groove between extensions of the plurality of extensions (groove between 54, 56). Regarding Claim 2, Reeves discloses the rotary machine, wherein an extension of the plurality of extensions is configured to flex toward the housing in response to a pressure differential across the rotor to provide a seal against the housing (54 configured to flex toward the housing 14 in response to a pressure differential across the rotor 16 to provide a seal against the housing 14). Regarding Claim 3, Reeves discloses the rotary machine, wherein an extension of the plurality of extensions comprises : an angled surface extending obliquely from the body toward the housing ( as seen in examiner annotated fig 2 below); and a distal surface that is offset from the housing to form a gap between the housing and the extension ( as seen in examiner annotated fig 2 below), wherein the angled surface is configured to direct fluid flow toward the distal surface to deflect fluid flow advancing toward the gap (angled surface as seen in examiner annotated fig 2 below configured to direct fluid flow toward the distal surface as seen in examiner annotated fig 2 below to deflect fluid flow advancing toward the gap as seen in examiner annotated fig 2 below). PNG media_image1.png 529 876 media_image1.png Greyscale Regarding Claim 4, Reeves discloses the rotary machine, wherein the plurality of extensions comprises a first extension extending obliquely from the body toward the housing (portion of 54 extends obliquely from 36) and a second extension extending orthogonally toward the housing (portion of 56 extends orthogonally to 14) to form the groove between the first extension and the second extension ( as seen in examiner annotated fig 2 above), and the groove is configured to form fluid flow vortices to disrupt fluid flowing between the housing and the flow restrictor (groove is configured to form fluid flow vortices to disrupt fluid flowing between the housing 14 and the flow restrictor 36). Regarding Claim 5, Reeves discloses the rotary machine, wherein the rotary machine comprises a plurality of zones (plurality of zones between plurality of 34, fig 1), each zone of the plurality of zones is configured to receive a different fluid flow ( each zone of the plurality of zones is configured to receive a different fluid flow), the housing comprises a sector plate ( housing 14 comprises sector plate 30) extending along a surface of the rotor between adjacent zones of the plurality of zones (30 extending along a surface of the rotor 14 between adjacent zones of the plurality of zones), and the flow restrictor extends between the plate of the plurality of plates of the rotor and the sector plate when the plate is in alignment with the sector plate (36 extends between 34 and 30). Regarding Claim 6, Reeves discloses the rotary machine, wherein the rotary machine comprises an outer wall (32, fig 1) positioned radially beyond the rotor (16), and the flow restrictor (36) extends between the plate of the plurality of plates of the rotor (plate 34) and the outer wall (32). Regarding Claim 7, Reeves discloses the rotary machine, wherein the housing comprises an inner structure (inner structure of 14) about which the rotor is configured to rotate (16 rotates on the inner structure of 14), and the flow restrictor extends between the plate of the plurality of plates of the rotor and the inner structure (36 between 34 and the inner structure of 14). Regarding Claim 9, Reeves discloses the rotary machine, comprising adsorbent material disposed in the openings defined between the plurality of plates (adsorbent material of 36 in the openings between plates 34, fig 1). Regarding Claim 10, Reeves discloses the rotary machine, wherein the rotary machine comprises a rotary heat exchanger (heat exchanger as described in the Field of the invention). Regarding Claim 11, Reeves discloses a flow restrictor ( 36) for a rotary machine (figs 1, 2 and 3), the flow restrictor comprising : a body (72) configured to attach to a rotor of the rotary machine (rotor 14), the rotor comprising a plurality of plates (plurality of 34), and the body (72) being configured to attach to a plate of the plurality of plates (34); and a plurality of extensions (54, 56) extending from the body (72) toward a housing (14) of the rotary machine (fig 1) to inhibit fluid flow between the housing (14) and the plate (34). Regarding Claim 12, Reeves discloses the flow restrictor, wherein an extension of the plurality of extensions is curved to form a convex surface facing the housing ( as seen in examiner annotated fig 2 above) and a concave surface opposite the convex surface ( as seen in examiner annotated fig 2 above). Regarding Claim 13, Reeves discloses the flow restrictor, wherein an extension of the plurality of extensions extends obliquely outward from the body toward the housing of the rotary machine (54, 56 extend obliquely toward 14, fig 3). Regarding Claim 17, Reeves discloses a flow restrictor (36) of a rotary machine (figs 1, 2 and 3), the flow restrictor comprising : a body (72) configured to attach to opposite sides of a plate (72 configured to attach to opposite sides of 34) of a rotor (14) of the rotary machine (fig 1); and an extension (54) extending from a distal end of the body ( 54 extends from distal end of 72), wherein the extension is configured to flex toward a housing of the rotary machine in response to a pressure differential across the rotor to provide a seal against the housing (the extension 54 is configured to flex toward a housing 14 of the rotary machine in response to a pressure differential across the rotor 16 to provide a seal against the housing 14). Regarding Claim 18, Reeves discloses the flow restrictor, wherein the extension extends from the body in a direction of rotation of the rotor (Col 4 Line 61 – Col 5 Line 5 : 54 extends from 72 in a direction of rotation of 16). Regarding Claim 19, Reeves discloses the flow restrictor, comprising an additional extension (58) extending from the distal end of the body in an opposite direction of rotation of the rotor (fig 2), wherein the extension and the additional extension form a groove therebetween (56 and 58 form a groove, fig 2). Regarding Claim 20, Reeves discloses the flow restrictor, wherein the extension is curved to form a concave surface facing the body and a convex surface facing away from the body ( as seen in examiner annotated fig 2 above). 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. Claims 8 and 14 - 16 are rejected under 35 U.S.C. 103 as being unpatentable over Reeves in view of Kozacka et al. (U.S. Patent # 5950707). Regarding Claim 8, Reeves discloses the rotary machine. Reeves does not disclose wherein the body comprises a spring configured to bias the plurality of extensions toward the housing. However, Kozacka teaches wherein the body comprises a spring (82, fig 5A) configured to bias the plurality of extensions toward the housing (82 biases extensions of 84 towards 22, fig 5A). It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the body of Reeves to comprise a spring as in Kozacka with a reasonable expectation of success so that the spring allows the seal assembly to absorb the mechanical stresses created by the reduction in distance between the rotor and the housing (Kozacka Col 9 Lines 32 – 34). Regarding Claim 14, Reeves discloses the flow restrictor. Reeves does not disclose wherein the body comprises a spring configured to bias the plurality of extensions toward the housing. However, Kozacka teaches wherein the body comprises a spring (82, fig 5A) configured to bias the plurality of extensions toward the housing (82 biases extensions of 84 towards 22, fig 5A). It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the body of Reeves to comprise a spring as in Kozacka with a reasonable expectation of success so that the spring allows the seal assembly to absorb the mechanical stresses created by the reduction in distance between the rotor and the housing (Kozacak Col 9 Lines 32 – 34). Regarding Claim 15, the combination of Reeves and Kozacka discloses the flow restrictor, wherein the body and the plurality of extensions are separate components coupled to one another (Reeves - body 72 and extensions 54, 56 are separate components coupled to one another). Regarding Claim 16, the combination of Reeves and Kozacka discloses the flow restrictor, wherein the body and the plurality of extensions are composed of different materials (Reeves - Col 3 Lines 51 – 53 - body 72 made of stainless steel; Col 3 Lines 63 – 65 : extensions 54, 56 made of Nickel alloy such as Inconel, Monel). Conclusion The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Any inquiry concerning this communication or earlier communications from the examiner should be directed to L. Susmitha Koneru whose telephone number is 571.270.5333. The examiner can normally be reached from Monday-Friday, 9:00 AM-4:00 PM. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Christine Mills can be reached on 571.272.8322. The fax phone number for the organization where this application or proceeding is assigned is 571.273.8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). /L. SUSMITHA KONERU/Examiner, Art Unit 3675
Read full office action

Prosecution Timeline

Feb 26, 2025
Application Filed
Feb 21, 2026
Non-Final Rejection — §102, §103 (current)

Precedent Cases

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
62%
Grant Probability
80%
With Interview (+17.8%)
3y 1m
Median Time to Grant
Low
PTA Risk
Based on 481 resolved cases by this examiner. Grant probability derived from career allow rate.

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