Prosecution Insights
Last updated: April 19, 2026
Application No. 18/796,419

Systems and Methods for Charge Imbalance Correction in Heat Pumps

Non-Final OA §102§103
Filed
Aug 07, 2024
Examiner
NORMAN, MARC E
Art Unit
3763
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Rheem Manufacturing Company
OA Round
1 (Non-Final)
84%
Grant Probability
Favorable
1-2
OA Rounds
2y 9m
To Grant
94%
With Interview

Examiner Intelligence

Grants 84% — above average
84%
Career Allow Rate
1117 granted / 1331 resolved
+13.9% vs TC avg
Moderate +10% lift
Without
With
+10.0%
Interview Lift
resolved cases with interview
Typical timeline
2y 9m
Avg Prosecution
41 currently pending
Career history
1372
Total Applications
across all art units

Statute-Specific Performance

§101
2.2%
-37.8% vs TC avg
§103
40.8%
+0.8% vs TC avg
§102
20.7%
-19.3% vs TC avg
§112
27.7%
-12.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1331 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. (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, 7, 9-10, and 14 is/are rejected under 35 U.S.C. 102(a)(1) and (a)(2) as being anticipated by Takeichi (US 10544957 B2). As per claim 1, Takeichi discloses a heat pump system 200 comprising: an indoor coil (12A, 12B); an outdoor coil 24; a first conduit (extending from right side of the indoor coils through valve 21, tank 22, compressor 23 to outdoor coil 24) and a second conduit (extending from right side of coil 24 through valve 26 and HX 27 to indoor heat exchangers 12A, 12B) connecting the indoor coil and the outdoor coil (Fig. 1; etc.); and an apparatus in fluid communication with the first conduit and the second conduit (the whole system is within fluid communication), the apparatus comprising: a tank 22 configured to receive liquid refrigerant from the first conduit or the second conduit in a heating mode of the heat pump system (Fig. 3, receives refrigerant from coil 24 at port B2; note that at least part of the refrigerant is in liquid phase which why accumulator tank 22 is required), and to provide the liquid refrigerant to the first conduit or the second conduit in a cooling mode (see col. 5, lines 6-19 re. switching to cooling operation; note that under such switching of the valve in Fig. 2 refrigerant still exits valve 21 at B3 and thus the tank 22 still receives refrigerant which is at least partly in a liquid phase) of the heat pump system; and a first valve 21 disposed between the tank and the first conduit (valve 21 lies along the second conduit, which is between the entrance of the tank 22 where refrigerant exits the first conduit at heat exchangers 12A, 12B). As per claim 7, Takeichi discloses wherein the first valve is a three-way valve or a four-way valve (Abstract, lines 1-2; etc.). As per claim 9, Takeuchi et al. wherein gaseous refrigerant flows through the first conduit between the indoor coil and outdoor coil, and wherein liquid refrigerant flows through the second conduit between the indoor coil and outdoor coil (based on refrigerant flows in Figs. 1, 3, 5, 7, etc.). As per claim 10, apparatus of a heat pump comprising: a tank 22 configured to receive liquid refrigerant from a first conduit or a second conduit in a heating mode of the heat pump system (Fig. 3, receives refrigerant from coil 24 at port B2; note that at least part of the refrigerant is in liquid phase which why accumulator tank 22 is required), and to provide the liquid refrigerant to the first conduit or the second conduit in a cooling mode (see col. 5, lines 6-19 re. switching to cooling operation; note that under such switching of the valve in Fig. 2 refrigerant still exits valve 21 at B3 and thus the tank 22 still receives refrigerant which is at least partly in a liquid phase) of the heat pump system; and a first valve 21 disposed between the tank and the first conduit (valve 21 lies along the second conduit, which is between the entrance of the tank 22 where refrigerant exits the first conduit at heat exchangers 12A, 12B). As per claim 14, again Takeichi discloses wherein the first valve is a three-way valve or a four-way valve (Abstract, lines 1-2; etc.). 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. 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. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claim(s) 2-6 and 11-13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Takeichi (US 10544957 B2) in view of Yoshizawa et al. (US 6684651 B1). As per claim 2, Takeichi wherein the first valve comprises a slide 212 disposed in the first valve, and wherein the slide comprises a cut-out region (Fig. 2; etc.). Takeichi does not teach a spring, wherein the spring is coupled to the slide, but instead uses a solenoid driver 213 to move the slide. Yoshizawa et al. teach a similar slide valve arrangement wherein a spring 13 is coupled to slide 27. It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly replace the solenoid of Takeichi with a spring driver as simply a generally known alternative valve drive mechanism for biasing and moving the slide. As per claims 3 and 11, Takeichi disclose wherein the first valve further comprises a first port B3, a second port B4, and a third port B2. Takeuchi does not teach wherein the first port is in fluid communication with the first conduit through a third conduit, wherein the second port is in fluid communication with the tank through a fourth conduit, and wherein the third port is in fluid communication with the second conduit through a fifth conduit. Yoshizawa et al. teach wherein the first port is in fluid communication with the first conduit through a third conduit 7, wherein the second port is in fluid communication with a fourth conduit 6, and wherein the third port is in fluid communication with the second conduit through a fifth conduit 8 (Fig. 1; etc.). It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly provide the connecting conduits of Yoshizawa et al. to the valve system of Takeichi for the same purpose of effectively connecting the refrigerant conduits to the valve ports. As per claims 4 and 12, Takeichi does not teach wherein the spring is in a default position while the heat pump system is in the heating mode, wherein the slide is located in a first position in the first valve while the spring is in the default position, wherein a first port and a second port of the first valve are in fluid communication via the cut-out region while the slide is in the first position. Yoshizawa et al. teach wherein the slide is located in a first position in the valve while the spring is in a default position, wherein a first port 11b and a second port 11a of the valve are in fluid communication via the cut-out region while the slide is in the first position (Fig. 2). It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly provide these spring-based valve controls to the system of Takeichi as an alternative valve drive mechanism to the solenoid driver for biasing and moving the slide between heating and cooling operations. As per claims 5 and 13, Takeichi does not teach wherein the spring is in a compressed position while the heat pump system is in the cooling mode, wherein the slide is located in a second position within the first valve while the spring is in the compressed position, wherein the second port and a third port of the first valve are in fluid communication through the cut-out region while the slide is in the second position. Yoshizawa et al. teach wherein the spring is in a compressed position while the heat pump is in a cooling mode, wherein the slide is located in a second position within the valve while the spring is in the compressed position, wherein the second port 11a and a third port 11c of the valve are in fluid communication through the cut-out region while the slide is in the second position (Fig. 3). Again, it would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly provide these spring-based valve controls to the system of Takeichi as an alternative valve drive mechanism to the solenoid driver for biasing and moving the slide between heating and cooling operations. As per claim 6, Takeichi do not teach wherein the slide of the first valve is configured to translate from a first position to a second position based on a pressure difference between the first conduit and the second conduit. Yoshizawa et al. teach wherein the slide of the first valve is configured to translate from a first position to a second position based on a pressure difference between the first conduit and the second conduit (see discussions of differential pressure controls at Abstract; col. 3, lines 36-42; col. 3, line 66 – col. 4, line 4; col. 4, lines 35-49; etc.). It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly control the valve of Takeichi for the same purpose of adjusting the direction of refrigerant flow according to operating conditions without the need for external motive force. Claim(s) 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Takeichi (US 10544957 B2) in view of Taras (US 2024/0125519 A1). As per claim 8, Takeichi does not teach wherein the first valve is different than an existing reversing valve in the heat pump system. However, heat pump systems with plural reversing valves are known in the art. Taras, for example, teaches a heat pump system (title, abstract, etc.) comprising a first reversing valve 103 and a second reversing valve 111, wherein each of the valves function within the system among inlet/outlet conduits and tanks (107, 114) in a similar arrangement to that of Takeichi. It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to modify the system of Takeichi to similarly comprise a both a first circuit and a second circuit for the purpose of achieving greater cooling/heating via the cascade arrangement. Under such an arrangement, adding a second circuit with a second reversing valve would implicitly involve adding a reversing valve different from an existing valve of the heat pump system. Claim(s) 15 is/are rejected under 35 U.S.C. 103 as being unpatentable over Takeichi (US 10544957 B2). As per claim 15, Takeichi does not teach wherein the tank is configured to adjust from a first internal volume to a second internal volume. However, according to Applicant’s disclosure (see para. 11), this simply means that different sizes of tanks can be installed into a system. Official notice is taken that adjusting the size of components is a simple mechanical expedient for optimizing operation under different system conditions. It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to arrange the system of Takeichi so that tanks of different size can be utilized within the system for this same basic purpose. Claim(s) 16-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yoshizawa et al. (US 6684651 B1) in view of Takeichi (US 10544957 B2). As per claim 16, Yoshizawa et al. disclose a valve for a heat pump, the valve comprising: a spring 13; a slide 27 connected to the spring and comprising a cut-out region 27a; a first port 11b in fluid communication with a first conduit (conduit leading to 9A); a second port 11a; and a third port 11c in fluid communication with a second conduit (conduit leading to 9B). Yoshizawa et al. do not teach wherein the second port is in fluid communication with a tank configured to temporarily store refrigerant, but rather is in communication with the inlet of compressor 4. Takeichi teaches a similar valve 21 wherein port B3 is in communication with accumulator tank 22 upstream of compressor 23. It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly locate an accumulator tank upstream of the compressor of Yoshizawa et al., such that the second port thereof is in communication with the tank, for the common purpose of separating gaseous from liquid refrigerant in order to protect against liquid refrigerant from entering the compressor. As per claim 17, Yoshizawa et al. disclose wherein the first port is in fluid communication with the first conduit through a third conduit 7, wherein the second port is in fluid communication with a fourth conduit 6, and wherein the third port is in fluid communication with the second conduit through a fifth conduit 8 (Fig. 1; etc.). Again, Yoshizawa et al. do not teach wherein the second port is in fluid communication with a tank. Again, Takeichi teaches a similar valve 21 wherein port B3 is in communication with accumulator tank 22 upstream of compressor 23. It would have been obvious to one of ordinary skill in the art at the effective filing date of the application to similarly locate an accumulator tank upstream of the compressor of Yoshizawa et al., such that the second port thereof is in communication with the tank, for the common purpose of separating gaseous from liquid refrigerant in order to protect against liquid refrigerant from entering the compressor. As per claim 18, Yoshizawa et al. disclose wherein the slide is located in a first position in the valve while the spring is in a default position, wherein a first port 11b and a second port 11a of the valve are in fluid communication via the cut-out region while the slide is in the first position (Fig. 2). As per claim 19, Yoshizawa et al. disclose wherein the spring is in a compressed position while the heat pump is in a cooling mode, wherein the slide is located in a second position within the valve while the spring is in the compressed position, wherein the second port 11a and a third port 11c of the valve are in fluid communication through the cut-out region while the slide is in the second position (Fig. 3). As per claim 20, wherein the valve is a three-way valve or a four-way valve (Abstract, lines 1-2; etc.). Cited Prior Art The following references not applied in the rejections above are considered pertinent to Applicant’s disclosed invention. Cochran (US 6058719) teach a refrigeration cycle with reversing valve 13 and refrigerant reservoir 26. Yoshimura et al. (US 7896029 B2) teach a four-way valve arrangement with slide 7. Hosoda et al. (US 3867960) teaches a reversing valve with a spring-driven slide arrangement. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to MARC E NORMAN whose telephone number is (571)272-4812. The examiner can normally be reached 8:00-4:30 M-F. 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, Frantz Jules can be reached at 571-272-6681. 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. /MARC E NORMAN/Primary Examiner, Art Unit 3763 /FRANTZ F JULES/Supervisory Patent Examiner, Art Unit 3763
Read full office action

Prosecution Timeline

Aug 07, 2024
Application Filed
Feb 13, 2026
Non-Final Rejection — §102, §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

1-2
Expected OA Rounds
84%
Grant Probability
94%
With Interview (+10.0%)
2y 9m
Median Time to Grant
Low
PTA Risk
Based on 1331 resolved cases by this examiner. Grant probability derived from career allow rate.

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