Ex Parte Alp et al

Patent Trial and Appeal BoardSep 27, 2012

11449933 (P.T.A.B. Sep. 27, 2012)

UNITED STATES PATENT AND TRADEMARKOFFICE UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O. Box 1450 Alexandria, Virginia 22313-1450 www.uspto.gov APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO. 11/449,933 06/09/2006 Abdullah B. Alp GP-308182-FCA-CHE 7133 65798 7590 09/28/2012 MILLER IP GROUP, PLC GENERAL MOTORS CORPORATION 42690 WOODWARD AVENUE SUITE 200 BLOOMFIELD HILLS, MI 48304 EXAMINER ENIN-OKUT, EDU E ART UNIT PAPER NUMBER 1727 MAIL DATE DELIVERY MODE 09/28/2012 PAPER Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE ________________ BEFORE THE PATENT TRIAL AND APPEAL BOARD ________________ Ex parte ABDULLAH B. ALP and David A. Arthur ________________ Appeal 2011-005323 Application 11/449,933 Technology Center 1700 ________________ Before TERRY J. OWENS, PETER F. KRATZ, and MARK NAGUMO, Administrative Patent Judges. NAGUMO, Administrative Patent Judge. DECISION ON APPEAL Appeal 2011-005323 Application 11/449,933 2 A. Introduction1 Abdullah B. Alp and David A. Arthur (“Alp”) timely appeal under 35 U.S.C. § 134(a) from the final rejection2 of claims 1-21. We have jurisdiction. 35 U.S.C. § 6. We AFFIRM. The subject matter on appeal relates to a fuel cell system in which the relative humidity of the cathode inlet air is maintained above a minimum level by a controller that performs at least one of three functions, namely (a) decreasing the temperature of the fluid that cools the fuel cell stack; (b) increasing the cathode pressure; or (c) decreasing the cathode stoichiometry. (Spec. 6 [0019].) The controller can also limit the power output of the fuel cell stack to keep the relative humidity (“RH”) of the cathode inlet. (Id.) The 933 Specification indicates that control of the RH is important to maintain the proper ionic resistance and the lifespan of the proton exchange membrane found in fuel cells for automobiles. (Id. at 3 [0007] and at 1 [0003].) Representative Claim 1 reads: A fuel cell system comprising: a fuel cell stack [12] receiving a cathode inlet airflow [14] and outputting a cathode exhaust gas flow [16]; 1 Application 11/449,933, System Level Adjustments for Increasing Stack Inlet RH, filed 9 June 2006. The specification is referred to as the “933 Specification,” and is cited as “Spec.” The real party in interest is listed as the General Motors Corporation. (Appeal Brief, filed 23 August 2010 (“Br.”), 3.) 2 Office action mailed 24 March 2010 (“Final Rejection”; cited as “FR”). Appeal 2011-005323 Application 11/449,933 3 a compressor [18] for providing the cathode inlet airflow to the stack; a water vapor transfer device [20] receiving the cathode inlet air flow [14] from the compressor [18] and the cathode exhaust gas flow [16] from the fuel cell stack, said water vapor transfer device using water vapor in the cathode exhaust gas to humidify the cathode inlet air; a coolant loop [28] for flowing a cooling fluid through the stack [12] to control stack temperature; and a controller [40] for controlling the relative humidity of the cathode inlet air [14] so that the relative humidity does not fall below a predetermined percentage, said controller [40] performing one or more of decreasing the temperature of the cooling fluid, increasing the cathode pressure, and decreasing the cathode stoichiometry to increase the relative humidity of the cathode exhaust gas [16] to prevent the relative humidity of the cathode inlet air [14] from falling below the predetermined percentage. (Claims App., Br. 18, indentation, paragraphing, emphasis, and square bracketed labels to Figure 1 (reproduced infra) added.) The Examiner maintains the following grounds of rejection:3 A. Claims 1-6, 10, 11, 12, and 16-21 stand rejected under 35 U.S.C. § 103(a) in view of the teachings of Formanski.4 3 Examiner’s Answer mailed 5 November 2010 (“Ans.”). 4 Volker Formanski et al., Fuel Cell System and Method of Operation, U.S. Patent Application Publication 2003/0072980 A1 (2003) (apparently App App B. base and claim repro assig this 5 Ke U.S. 6 93 eal 2011-0 lication 11 B. C 35 Fo Discussi Initially, d on limita 13-21 stan 6. 37 C. The clai duced bel {Figure ned to Ge appeal: see isuke Suz Patent Ap 3 Specific 05323 /449,933 laims 7, 8, U.S.C. § rmanski, on we find th tions recit d or fall w F.R. § 41.3 med fuel c ow. 1 shows an neral Moto the corre uki, Appar plication P ation, page 9, and 13- 103(a) in v Suzuki,5 an at Alp on ed in claim ith claim 1 7(c)(1)(vi The clai ell system embodim rs Corpor spondence atus for C ublication 8, Equati 4 15 stand r iew of the d admitte ly presents s 1 and 6 , and claim i) (2011). med inven 10 is illus ent of the ation, the p address o ontrolling 2003/002 ons (1), (2 ejected un combine d prior art argument . Accordin 12 stand tion trated in F claimed fu resent rea n the face Electric P 2034 A1 ( ), and (3). der d teaching .6 s for paten gly, claim s or falls w igure 1, w el cell sys l party in of the pub ower from 2003). s of tability s 2-11 ith hich is tem} interest in lication.) Fuel Cell , Appeal 2011-005323 Application 11/449,933 5 Air is compressed in compressor 18, on the left of Figure 1, and introduced to the cathode inlet of fuel cell stack 12 after passing through water vapor transformer 20. (Spec. 5 [0015].) Oxygen in the air reacts with hydrogen ions generated in the fuel cell to produce water, which is carried in the cathode exhaust gas 16 to water vapor transformer 20. (Id.) Coolant is circulated in a cooling loop 28 that passes through fuel cell stack 12, carrying away heat generated by the chemical reactions in the fuel cell. (Id. at [0016].) The temperature T, pressure P, and relative humidity RH are monitored by sensors, and the values are communicated to controller 40. (Id. at 6 [0017].) Controller 40 can control “backpressure valve 42 positioned in the cathode exhaust gas line 14 after the WVT device 20 for controlling (increasing) the pressure of the cathode side of the stack 12.” (Spec. 5-6 [0016].)7 Controller 40 can also control (decrease) the temperature of the coolant, decrease the cathode stoichiometry, and limit the power output of the stack. (Id. at 6 [0019].) All of these controlling steps are said “to increase the relative humidity of the cathode exhaust gas that is used by the WVT device 20 to humidify the cathode inlet air.” (Id.) Formanski The Examiner finds, and Alp does not dispute, that Formanski describes a fuel cell system illustrated in Figure 1, reproduced on the following page, in which air is compressed by compressor 67, humidified in 7 The description in the text does not appear to match the Figure, but the differences are not relevant to the resolution of this appeal. Appeal 2011-005323 Application 11/449,933 6 humidifier 81 by water collected in container 75 from the cathode exhaust 73 of fuel cell stack 11, and introduced to the cathode inlet 71 of the fuel cell stack 11. (Ans. 3-4.) Fuel cell stack 11 is also cooled via a cooling system that circulates cooling fluid through the stack via pump 79, radiator 27, and associated plumbing. (Ans. 3-4.) {Formanski Figure 1 is shown below} {Figure 1 shows an embodiment of the Formanski fuel cell system} The Examiner finds further that humidity control 176 (see Formanski Figure 2, not reproduced here), which is either a component of control system 29 (lower right in Fig. 1) or connected to it, “determines the stack operating pressure required in order to obtain a desired characteristic humidity number FK” by controlling motor 65 of compressor 67 and restrictor valve 77, according to the curves shown in Figure 10, which is reproduced on the following page. (Ans. 4, 1st full para.) Appeal 2011-005323 Application 11/449,933 7 {Formanski Figure 10 is shown below} {Fig. 10 shows characteristic humidity [FK] versus stack operation pressure at 80°C, 70°C, and 60°C, at constant stoichiometry and relative humidity} Alp argues that “Formanski does not teach or suggest a system or method that controls the relative humidity of the cathode inlet from falling below a predetermined percentage.” (Br. 13, 1st full para.) In Alp’s view, the characteristic humidity value cited by the Examiner, “is nothing more than an operating parameter utilized by Formanski to determine a desired operating pressure.” (Id. at 14, 1st para.) Nothing in Formanski, according to Alp, “remotely teaches or suggest a method to control relative humidity, much less a method that controls the relative humidity of the cathode inlet from falling below a predetermined percentage” as recited in claim 1. (Id.) Appeal 2011-005323 Application 11/449,933 8 These arguments are not persuasive of harmful error in the Examiner’s rejection. Figure 10 shows the characteristic humidity number, FK, at the cathode outlet, as a function of stack operation pressure, which appears to be the same as or closely related to the “cathode pressure” recited in the claim.8 At constant temperature, e.g., along the line labeled 80°C, as the stack operation pressure increases, the characteristic humidity FK increases, while the stoichiometry at the anode and the cathode remain constant, and while the relative humidity at the cathode inlet (and also at the anode inlet) remains constant at 50%. Moreover, as the stack temperature is decreased to 70°C and then to 60°C, i.e., as the temperature of the cooling fluid circulating through the fuel cell stack is decreased, FK increases. The humidity control system is designed to maintain the relative humidity at the cathode inlet at 50%. Moreover, as the Examiner demonstrated, and as Alp does not deny, Formanski describes a fuel cell system in which the relative humidity at the cathode inlet, which influences the respective magnitude of the characteristic humidity number and which is the determining factor for the selection of the respective family of curves for the regulation of the prevailing operating pressure in order to achieve the desired characteristic humidity number FK, varies depending on the humidity of the environmental air sucked in by the air compressor. It can, however, also be influenced by humidifying devices which are sometimes provided in order 8 Compare “[a] compressed flow of an oxygen containing gas is provided to a cathode inlet at the operating pressure.” (Furmanski 1 [0005]) with “[t]he controller 40 may increase or decrease the cathode pressure within the stack 12 by closing and opening the backpressure valve 42. The pressure sensor 32 will measure the change in the cathode pressure” (Spec. 7 [0020]). Appeal 2011-005323 Application 11/449,933 9 to ensure an adequate relative humidity at the cathode side and/or at the anode side of the fuel cell stack. (Formanski 4 [0057]; emphasis added.) Thus, as indicated by the cycling of the water produced in the fuel cell stack through container 75 and humidifier 81 to humidify air introduced to the cathode input, Formanski teaches the artisan that the relative humidity of the air introduced at the cathode inlet is affected by the humidity at the cathode outlet. As our reviewing court explained recently, “[a] recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective.” In re Applied Materials, ___ F.3d ___, ___, 103 USPQ2d 2000, 2005, 2012 WL 3711586, *6 (29 August 2012). The manipulation of variables recognized as being result-effective to find optimum or workable ranges by routine experimentation is generally regarded as within the level of ordinary skill in the art, and therefore prima facie obvious. (Id. at *4, citing cases.) In summary, Formanski demonstrates that the relation between the cathode pressure and the characteristic humidity FK, and between the fuel cell stack temperature—and hence the coolant temperature—and FK, were known, and that the further relation to relative humidity at the cathode inlet was known. In other words, Figure 10 shows that the cooling fluid temperature and the cathode pressure were both recognized as result- effective variables for the RH at the cathode inlet. In fact, the relations were sufficiently well known that, as shown in Figure 10, the cathode pressure and the fuel stack temperature could be used to control the RH at the cathode Appeal 2011-005323 Application 11/449,933 10 inlet at 50%. We conclude that Formanski does not support Alp’s argument that these relations and their consequences were unknown.9 As Alp has not shown harmful error in the Examiner’s rejection of claim 1, we AFFIRM the rejection of claims 1-5, 7-11 and 13-21. Alp argues that claims 6 and 12 are patentable because they recite a system in which, when none of the control mechanism recited in claims 1 and 12, respectively, are effective, the controller limits the fuel cell stack output. (Br. 16.) Because the system required by claim 1 is not described or suggested by Formanski, Alp argues, it follows that Formanski cannot teach or suggest the further step. (Id.) There are several problems with this argument. First, we have rejected the premise of Alp’s argument by finding that the Examiner did not err in concluding that Formanski rendered claims 1 and 12 obvious. A false premise cannot be the basis for a valid conclusion. Second, Alp has not responded to the Examiner’s reasoning that, given the knowledge that the humidity should be controlled to ensure damage-free operations of fuel cells, and that the operating temperature should also be controlled, that it would have been obvious to limit the power output in order to avoid failure of the fuel cells. (Ans. 5, last two paras.) Finally, claims 6 and 12 are not within 9 By the same reasoning, Furmanski Figures 3-5 illustrate the inter-relation of FK (and thus the relative humidity at the cathode inlet) with the cathode pressure and the cathode stoichiometry (Fig. 3); FK and the cooling fluid temperature and the cathode stoichiometry (Fig. 4); and FK with the cathode pressure and the cooling fluid temperature (Fig. 5). Appeal 2011-005323 Application 11/449,933 11 the scope of claims 1 and 12, from which they depend, because they negate the control required by the independent claims.10 We conclude that Alp has not shown harmful error in the rejections of claims 6 and 12, and we AFFIRM the rejection of those claims. C. Order We AFFIRM the rejection of claims 1-6, 10, 11, 12, and 16-21 under 35 U.S.C. § 103(a) in view of the teachings of Formanski. We AFFIRM the rejection of claims 7, 8, 9, and 13-15 stand rejected under 35 U.S.C. § 103(a) in view of the combined teachings of Formanski, Suzuki, and admitted prior art. No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. § 1.136(a). AFFIRMED cam 10 Cf. Spec. 6 [0019], describing limitation of the power output as an additional control mode.