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 .
Status of Application
Claims 1, 6, 9, 11-12, and 14 are amended with claims 11-20 remaining withdrawn, submitted on 10/24/2025. Claims 1-10 are presented for examination.
The previous 35 U.S.C. 103 rejections to claims 1-10 are maintained.
Response to Arguments
Applicant’s arguments regarding claim 1 filed on 10/24/2025 have been fully considered but they are not found persuasive.
First, the Applicant argues that Yang cannot disclose, teach or suggest that it has multiple BBUs in a rack.
The Examiner respectfully submits that Yang discloses the power supply unit (PSU) 950 and/or backup-battery unit (BBU) 910 may be inserted into any of server slots 903 within the electronic rack 1100 ([0036]), which at least discloses the electronic rack 1100 could hold both PSU 950 and BBU 910 simultaneously and at any layer of the server slots 903. A skilled artisan would reasonably envisage when needed, a plurality of PSU 950 and/or BBU 910 could be held within the space of each and every server slots 903 with a reasonable expectation of success based on Yang’s disclosure, which is further evidenced by Gao US 10727553 B1 at Col5/Ln41-43, quote “the same BBU shelf unit may be populated with different numbers of backup battery modules”. Thus, this argument is not found persuasive.
Second, the Applicant argues that Feng does not disclose about the spacing between its lithium battery units, and Feng’s use of liquid level sensor 23 eliminates any need to determine in advance or use a particular spacing of its lithium battery units.
The Examiner respectfully disagrees because: 1) primary reference Yang has rendered obvious a plurality of BBUs being held in the electronic rack 1100, as set forth above; 2) the electronic rack 1100 of Yang has shown slots with spacing in ascending order (FIG. 11), therefore, the claimed limitation of “the battery cells are stacked in ascending order” is obvious to meet; 3) the claim does not actually require “spacing between its lithium battery units” nor “determined in advance or use a particular spacing” as Applicant argues; 4) the claimed limitation of “an initial distance between a liquid surface of the two-phase cooling fluid and the top surface of the Nth battery cell, and an inter-cell distance between the top surface of each pair of consecutive battery cells in the stack” is inherently included in modified Yang’s set-up with the battery modules being stacked in ascending order. Thus, this argument is not found persuasive.
Third, the Applicant argues that Feng’s use of liquid level sensor 23 eliminates/teaches away from the need for any particular spacing between batteries.
The Examiner respectfully submits modified Yang has included spacing, an initial distance and an inter-cell distance between batteries in FIG. 11, even though the claim does not actually require the argued term “spacing”. Feng is not cited for teaching any particular spacing between batteries, thus this argument is irrelevant thus moot.
While modified Yang does not explicitly disclose “an initial distance…, and an inter-cell distance…, are determined based on the storage capacity of the battery cells and the thermal properties of the two-phase cooling fluid”, Feng teaches the control of a refill amount of the cooling liquid can be calculated or determined in a preset closed container with a known or measurable surface area of the container base, through the height of the liquid level being refilled above the energy storage lithium battery, in which the height of the liquid level corresponds to an initial distance and an inter-cell distance of the claim. Therefore, Feng’s liquid level reading from sensor 23 is used to control the refill amount of the cooling liquid, and associates to the heat removal ability of the two-phase cooling liquid being determined based on the thermal properties of the two-phase cooling fluid as further taught by Rae (Table 2 on P7).
Thus, this argument is not found persuasive.
Claim Rejections - 35 USC § 103
1. 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.
2. The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied 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.
3. Claims 1-10 are rejected under 35 U.S.C. 103 as being unpatentable over Yang (US 20210057787 A1) in view of Feng (CN 113764755 A, see machine translation for citation), as evidenced by Drake (Journal of Power Sources 285 (2015) 266-273), and further in view of Rae (Journal of Power Sources 525 (2022) 231094).
Regarding claim 1, Yang discloses a battery backup unit (BBU) for datacenter application (Abstract) comprising: an information technology (IT) enclosure (electronic rack 1100, [0036] and FIG. 11) adapted to hold a two-phase cooling fluid (a two-phase coolant, [0035] and FIG. 10).
Yang discloses the BBU 910 may be inserted into any server slots 903 within the electronic rack 1100 ([0036]) which renders obvious the claimed “a battery stack adapted to be positioned within the IT enclosure and submerged in the liquid phase of the two-phase cooling fluid” because BBU 910 ([0036]) or backup battery module 1000 ([0035] and FIG. 10) corresponds to a battery stack in the claim. Yang further discloses the battery stack (battery module 1000, [0035] and FIG. 10) including N battery cells (battery cells 302, [0035] and FIG. 10), N ≥ 2, each battery cell having a top surface (FIG. 10).
Yang includes the BBU 910 being inserted into any server slots 903 within the electronic rack ([0036] and FIG. 11), which renders obvious the claimed “the battery cells are stacked in ascending order, the first battery cell being the lowest battery cell in the battery stack and the Nth battery cell being the highest battery cell in the battery stack”, as arranged in the ascending layers of the rack shown in FIG. 11.
Yang further discloses the desire to provide thermal management to battery cells for managing the temperature of a backup battery unit for data center applications ([0018]) and the speed of discharging is positively correlated with the heat generated ([0017]). Yang discloses a control algorithm may take measurements from one or more sensors, including liquid level sensor 112 (FIGs. 1 and 2) and the control algorithm may execute a self-inspection process for both the cooling and power components in the BBU immersion cooling system ([0019]) and a liquid-level sensor is placed inside the immersion tank for self-inspection and protection purposes ([0020] and FIGs. 1 and 2); the microcontroller receives a signal from the liquid-level sensor indicating that the liquid level in the immersion tank has exceeded a threshold level (claim 9), and to control the temperature of the battery cells, a pump is attached to the immersion tank that pumps cooling liquid into the immersion tank ([0018]).
However, Yang does not explicitly disclose that an initial distance between a liquid surface of the two-phase cooling fluid and the top surface of the Nth battery cell, and an inter-cell distance between the top surfaces of each pair of consecutive battery cells in the stack, are determined based on the storage capacity of the battery cells and the thermal properties of the two-phase cooling fluid.
Feng teaches a forced circulation cooling and heat dissipation device for energy storage lithium batteries, comprising at least one group of energy storage lithium battery units 1, a liquid level sensor 23, a control mechanism 3 and a heat dissipation mechanism 5 including a liquid replenishing tank 8 ([0044] [0053] and FIGs. 1 and 2); the liquid level sensor 23 is arranged above the energy storage lithium battery and is used to detect the liquid level of the coolant 13 in the container ([0046]), the control mechanism 3 is communicated with the liquid replenishing tank 8, and at least one valve 71 is arranged on the circulation pipeline 7 to adjust the liquid level of the coolant 13 in the closed container 12, and the opening of the valve 71 is adjusted to control the refill amount to refill the closed container 12 of each group of energy storage lithium battery units 1 ([0053] and FIGs. 1 and 2). Therefore, Feng teaches a heat dissipation mechanism 5 that adjusts and controls the refill amount of cooling liquid to refill the closed container 12 of each group of energy storage lithium battery units 1 based on the signal obtained from the liquid level sensor 23 determining the liquid level above the energy storage lithium battery as shown in FIGs. 1 and 2, which renders obvious the claimed “an initial distance between a liquid surface of the two-phase cooling fluid and the top surface of the Nth battery cell, and an inter-cell distance between the top surfaces of each pair of consecutive battery cells in the stack, are determined based on the storage capacity of the battery cells and the thermal properties of the two-phase cooling fluid”, because the controlled refill amount of the cooling liquid of Feng can be calculated or determined in a preset closed container with a known or measurable surface area of the container base, through the height of the liquid level being refilled above the energy storage lithium battery which corresponds to an initial distance and an inter-cell distance of the claim. Further, it is well-known in the art that the heat generated by the battery cells is related to the storage capacity of the battery cell as evidenced by Drake (Equation 1 on P267); and the heat removal ability of the two-phase cooling liquid is related to the thermal properties of the two-phase cooling fluid as taught by Rae (Table 2 on P7).
It would have been obvious before the effective filing date of the claimed invention, for an ordinary skilled artisan to have determined the amount of cooling liquid being pumped into the immersion tank of Yang by adopting extra liquid level sensors above the energy storage lithium battery and determining the height of the liquid level being refilled, as taught by Feng and based on the storage capacity of the battery cells and the thermal properties of the cooling fluid as further taught by Rae, thus arrive at the claimed limitation “an initial distance between a liquid surface of the two-phase cooling fluid and the top surface of the Nth battery cell, and an inter-cell distance between the top surfaces of each pair of consecutive battery cells in the stack, are determined based on the storage capacity of the battery cells and the thermal properties of the two-phase cooling fluid”, in order to control the temperature of the battery cells for data center applications as desired by Yang, without undue experimentation and with a reasonable expectation of success. [MPEP 2144.05(II)].
Regarding claim 2, modified Yang discloses all of the limitations as set forth above. While modified Yang does not explicitly disclose that the thermal properties of the two-phase cooling fluid include its specific heat capacity and evaporation rate, Rae further teaches in 2-phase systems, the performance of ability to remove heat is achieved partially through the latent heat of evaporation of the liquid-to-gas phase transition (Abstract), and key figures of merit of cooling fluid suitable for immersion cooling include specific heat capacity, boiling point etc. (Table 2/P7 and Table3/P10 ). It would have been obvious before the effective filing date of the claimed invention, for an ordinary skilled artisan to have recognized that the thermal properties of the two-phase cooling fluid include its specific heat capacity and evaporation rate because evaporation rate of the two-phase cooling fluid in the immersion tank of modified Yang is closely related to the key figures of thermal properties such as specific heat capacity, boiling point etc. as taught by Rae.
Regarding claim 3, modified Yang discloses all of the limitations as set forth above. Since modified Yang includes each battery stack being inserted into any server slots 903 within the electronic rack ([0036] and FIG. 11), modified Yang functions substantially equivalent to the claimed feature such that each battery stack being supported by a pair of multi-function units (a pair of left and right sides frames of the server slots 903 [0036] and FIG. 11), wherein each multi-function unit includes a stacking structure with a set of supports (supporting layer for server blades [0036] FIG. 11)), the distance between supports providing the required inter-cell distance for a given battery cell power capacity, and wherein each battery cell in the battery stack is supported by a pair of corresponding supports, one from each multi-function unit (FIG. 11).
Regarding claim 4, modified Yang discloses all of the limitations as set forth above. Since modified Yang further discloses the block diagram illustrating a power architecture design for a back-up-battery unit (BBU) immersion cooling system each includes a liquid-level sensor 112 (FIGs. 1 and 2), a skilled artisan would reasonably acknowledge that each BBU 910 in the electronic rack 1100 as shown in FIG. 11 necessarily and inherently further comprises at least one liquid-level sensor 112, therefore the battery backup unit represented in multiple of BBU 910 comprises: N liquid-level sensors.
Further since modified Yang includes a liquid level sensor 112 with each BBU immersion cooling system 100 ([0031]) and the liquid-level sensor 112 is placed inside the immersion tank for self-inspection and protection purposes ([0020]), a skilled artisan would reasonably expect to position each liquid-level sensor 112 of modified Yang substantially aligned with the top surface of a corresponding battery cell in order to ensure that the batter cells are immersed in the cooling liquid.
Modified Yang further discloses N switches (switch 130, FIGs. 1 and 2), each coupled to a corresponding battery cell; and a controller (microcontroller 150, FIGs. 1 and 2) communicatively coupled to the N liquid-level sensors and the N switches (FIGs. 1 and 2), wherein the controller uses each switch to turn off the corresponding battery cell when the corresponding liquid-level sensor determines that the top surface of the battery cell is no longer submerged in the two-phase cooling fluid ([0020] and FIGs. 1 and 2).
Regarding claim 5, modified Yang discloses all of the limitations as set forth above. Since modified Yang further discloses the battery cells 110 are electrically connected with microcontroller 150, I-sensor 120, and external power connection (FIGs. 1 and 2), a skilled artisan would reasonably expect that modified Yang further comprises an electrical bus electrically coupled to the N battery cells in the battery stack for an easy arrangement of above electrically connected components (microcontroller 150, I-sensor 120, and external power connection etc. FIGs. 1 and 2).
Regarding claim 6, modified Yang discloses all of the limitations as set forth above. Modified Yang further discloses further comprising a vapor collector (vapor space 313, FIG. 10) coupled to a top of the IT enclosure.
Regarding claim 7, modified Yang discloses all of the limitations as set forth above. Modified Yang further discloses the vapor collector is external (vapor line 310), or partially internal and partially external ([0035] and FIG. 10).
Regarding claim 8, modified Yang discloses all of the limitations as set forth above. Modified Yang further discloses the vapor collector has a fluid inlet, a fluid outlet (FIG. 10), and a pump coupled in the fluid inlet to circulate an external cooling fluid through the vapor collector (FIGs. 1,2, and 10).
Regarding claim 9, modified Yang discloses all of the limitations as set forth above. Modified Yang discloses BBU 910 may be inserted into any of server slots 903 within the electronic rack 1100 ([0036] and FIG. 11), which renders obvious at least one additional battery stack positioned in the IT enclosure and submerged in the two-phase cooling fluid.
Regarding claim 10, modified Yang discloses all of the limitations as set forth above. However, modified Yang does not expressly disclose the additional battery stack has M battery cells and wherein M≠ N.
Feng further teaches in embodiment 2, two groups of energy storage lithium battery units 1 within a separate mounting frames 121 provided inside the two sealed container 12 ([0064] FIG. 2). Although Feng shows a same amount of battery cells in the two sealed container 12 (FIG. 2), it is merely for exemplary description purpose. A skilled artisan would reasonably expect that even with a different number of battery cells in the two sealed container 12 (M≠ N), the cooling and heat dissipation device for the two groups of energy storage lithium battery units would function substantially equivalent without drastic effect because the two battery stacks are physically separated by the two mounting frame 121 in Feng.
It would have been obvious before the effective filing date of the claimed invention, for an ordinary skilled artisan to arrive at the claimed “the additional battery stack has M battery cells and wherein M≠ N” as taught by Feng without undue experimentation and with a reasonable expectation of success.
Conclusion
4. THIS ACTION IS MADE FINAL. 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 mailing date of this final action.
5. Any inquiry concerning this communication or earlier communications from the examiner should be directed to KAN LUO whose telephone number is (571)270-5753. The examiner can normally be reached 8:00AM -5:00PM ET. ET.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jonathan Leong can be reached on (571)270-1292. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/K. L./Examiner, Art Unit 1751 1/23/2026
/JONATHAN G LEONG/Supervisory Patent Examiner, Art Unit 1751 2/2/2026