DETAILED ACTION
Response to Amendment
This Office action addresses claims 1-10. Although claim 1 was amended, claims 1, 2, 4, and 6 remain rejected over DE ‘324 under 35 USC 102 and claims 1-10 are newly rejected under 35 USC 103 over Berner as necessitated by amendment. Accordingly, this action is made final.
Claim Rejections - 35 USC § 102
Claims 1, 2, 4, and 6 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by DE 11-2011-103324T5. Regarding claim 1, the reference is directed to a fuel cell stack comprising a plurality of fuel cells stacked in a stacking direction (Figs. 1 and 7, [0014] of translation), wherein at least one fuel cell comprises a compressible woven fabric structure (8, 9) made from metal fibers (Figs. 2, 3, abstract, [0016]). Further regarding claim 1, the fabric structure has a spring function ([0016]) and inherently has a spring constant as claimed. In addition, it is disclosed in [0016] that the stack is pressurized (“P” in Figures 1 and 2). Thus, the limitation reciting “by the spring function a change in length of the fuel cell along the stacking direction arising from changes in an operating state of the fuel cell stack can be equalized by an opposite and negative change in length of the compressible fabric structure such that a length of the fuel cell stack in the stacking direction is maintained constant regardless of the operating state” is met because the stack of the reference would be fully capable of performing in the claimed manner (MPEP 2114). Regarding claim 2, each of the fuel cells can comprise at least one compressible fabric structure ([0036]). Regarding claim 4, the compressible fabric structure can be formed by wave-shaped fibers, which provide the spring function (Fig. 1, [0038]). Regarding claim 6, the fibers providing the spring function can be made of a metal ([0038]). Thus, the instant claims are anticipated.
Claim Rejections - 35 USC § 103
Claims 1-8 and 10 are rejected under 35 U.S.C. 103(a) as being unpatentable over Berner et al (US 20190334182).
Regarding claim 1, the reference is directed to a fuel cell stack comprising a plurality of fuel cells stacked in a stacking direction (Fig. 1), wherein at least one fuel cell comprises a compressible interwoven fabric structure (80) made from wires, threads, or fibers (Figs. 2, 3, abstract, [0014]). Further regarding claim 1, the fabric structure inherently has a spring function having a spring constant as claimed, because it would exhibit at least some degree of spring-like behavior (based on shapes and orientations of fibers, see for example Figs. 3 and 4). Regarding claim 2, each of the fuel cells can comprise at least one compressible fabric structure ([0033] et seq). Regarding claim 3, the fabric structure is formed from interwoven fibers, and the spring function is produced by a nonordered arrangement of the fibers (Fig. 3). Regarding claim 4, the compressible fabric structure can be formed by wave-shaped fibers, which provide the spring function (Fig. 2). Regarding claim 6, the fibers providing the spring function can be made of a metal or a plastic ([0017], [0019], [0040]). Regarding claim 7, the fabric structure can have a first region having a first spring constant and a second region having a second spring constant different from the first (structure can be made of different materials, which are layered, [0022]; different materials would have different constants). Regarding claims 8 and 10, the fuel cells each have an active region and three media guides for fuel, oxidant, and coolant (50, 60, 70), and the fuel cells can comprise three compressible fabric structures within the three media guides ([0034]-[0036]).
The reference does not expressly teach that a change in length of the fuel cell along the stacking direction arising from changes in an operating state of the fuel cell stack can be equalized by an opposite and negative change in length of the compressible fabric structure such that a length of the fuel cell stack in the stacking direction is maintained constant regardless of the operating state, as recited in claim 1. Specifically, reference does not appear to teach that the stack is pressurized.
However, the invention as a whole would have been obvious to one skilled in the art at the time of filing because a skilled artisan would be motivated to add the feature of pressurizing the fuel cell stack of Berner et al., which is routine in the art (i.e., by using tie rods), to provide sufficient contact between the layers of the stack. Upon making this modification, the resulting stack would be fully capable of performing the claimed function of a change in length being equalized by a change in length of the compressible fabric structure such that a length of the fuel cell stack in the stacking direction is maintained constant regardless of the operating state, as recited in the claim. See MPEP 2114.
The reference further does not expressly teach that the fabric is formed from interwoven fibers having a mean first amplitude, a wave shaped resilient fiber having a mean second amplitude is present to provide the spring function, and the mean second amplitude is greater than the mean first amplitude as recited in claim 5.
However, the invention as a whole would have been obvious to one skilled in the art at the time of filing because the artisan would be sufficiently skilled to tailor the different fibers (81, 82, 83) of Berner et al. so as to provide the claimed configuration. Initially, Fig. 3 of the reference schematically shows wave-shaped fibers 82 (carbon fibers) as having larger mean amplitude than other fibers in the structure. Further, paragraph [0024] discloses that “different materials with desired properties may be advantageously combined…The height of the woven fabric, that is the extension perpendicularly to the woven fabric plane, may be adapted to the height of the distributing region for example by using thicker fibers.” Accordingly, it would have been obvious to use different fibers in the same structure having different properties and dimensions. Therefore the claimed configuration of wave shaped fibers having a mean amplitude larger than the mean amplitude of other fibers in the structure as recited in claim 5 would be rendered obvious.
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Berner et al. as applied to claims 1-8 and 10 above, and further in view of LaConti et al (US 20020144898).
Berner et al. does not expressly teach that different spring constants are associated with each of the first, second, and third fabric structures of the different media guides as recited in claim 9.
LaConti et al. is directed to a PEM electrochemical cell that comprises compressible two metal screens (31, 33), or a metal screen (31) and a graphite fiber mat (pad 105) within the fluid flow spaces on opposite sides of the membrane electrode assembly (Fig. 3, [0040]).
Therefore, the invention as a whole would have been obvious to one skilled in the art at the time of filing because a particular known technique (using fibrous/fabric structures made of different materials in different areas of an electrochemical cell) was recognized as part of the ordinary capabilities of one skilled in the art. KSR v. Teleflex, 82 USPQ2d 1385, 127 S. Ct. 1727 (2007). Depending on the specific chemistry of the cell and other factors such as compression level, it would have been obvious to use different materials in the different media guide areas of Berner et al, and accordingly, the limitation that each of the first, second and third spring constants are different would have been obvious. As also noted above, Berner et al. discusses tailoring fabric layers to provide specific desired properties. It would have at least been obvious to use different materials (or combinations of materials) that are designed to be more stable with regard to corrosion in a specific media environment (i.e., reducing, oxidizing, water environments if coolant is water). As such, the different structures would have different spring constants. Accordingly, claim 9 would be rendered obvious.
Response to Arguments
5. Applicant’s arguments filed March 25, 2026 have been fully considered but they are not persuasive. Applicants state that none of the cited references teach or suggest a fuel cell stack arrangement that is able to maintain a constant length in a stacking direction regardless of the operating state by using a compressible fabric structure. However, for the reasons set forth in the rejections above, the DE ‘324 reference teaches a fuel cell stack structure that has this capability, and the Berner et al. reference can be modified to add a pressurizing element on the stack, such that it would be capable of performing the claimed function. The Examiner notes that the language added by amendment is functional in nature, and the prior art is capable of performing the function for the reasons set forth in the rejections. See MPEP 2114.
Conclusion
6. 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 extension fee 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 date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Jonathan Crepeau whose telephone number is (571) 272-1299. The examiner can normally be reached Monday-Friday from 9:30 AM - 6:00 PM EST.
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/Jonathan Crepeau/
Primary Examiner, Art Unit 1725
June 3, 2026
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