DETAILED ACTION
Response to Amendment
The Amendment filed January 16, 2026 has been entered. Claims 1 – 4 are pending in the application. The amendment to the claims has overcome the claim objections set forth in the last Non-Final Action mailed October 22, 2025.
Claim Rejections - 35 USC § 103
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.
Claims 1 – 3 are rejected under 35 U.S.C. 103 as being unpatentable over Yamashita et al. (US 2021/0062811 – herein after Yamashita) in view of Lifson, Alexander (US 6,305,914 – herein after Lifson) and evidenced by Defranciscis et al. (US 2018/0320557 – herein after Defranciscis).
In reference to claim 1, Yamashita teaches a scroll electric compressor (see fig. 1) comprising:
a rotary shaft (5);
a motor (7) including a rotor (7b) fixed to the rotary shaft, and a stator (7a) having a cylindrical shape and surrounding the rotor (as evident from fig. 1);
a compression part (9+11) configured to compress fluid with rotation of the rotary shaft (5);
a housing (1) accommodating the motor and the compression part;
the compression part (9+11) including a fixed scroll (9) and an orbiting scroll (11) configured to make orbital motion with the rotation of the rotary shaft, disposed in the housing, the fixed scroll and the orbiting scroll cooperating to form a compression chamber (49) in which the fluid is compressed;
the housing having a motor housing (13) accommodating the motor, a compression part housing (15) accommodating the compression part, a shaft support housing (3) rotatably supporting the rotary shaft between the rotor and the orbiting scroll;
a balance weight (33) being fixed to the rotary shaft, extending in a radial direction (→ direction in view of fig. 1) of the rotary shaft, and facing the rotor (7b) and the shaft support housing (3) in an axial direction (↨ direction in view of fig. 1) of the rotary shaft;
a plurality of stacking steel plates (701, see ¶43) being stacked in the axial direction to form the rotor (7b);
the rotor having a plurality of fluid flow holes (77a-77e; see figs. 1, 4 and 5 & ¶46-¶47) through which the fluid flows, the fluid flow holes being disposed in a circumferential direction of the rotor (as evident from figs. 4-5) and extending through the rotor in the axial direction (as evident from fig. 1); and
the stacking steel plates each having a plurality of flow holes (individual holes in each of the stacked steel plates forming the asserted fluid flow holes), the stacking steel plates being stacked so that the flow holes form the fluid flow holes, wherein
the rotor has a balance adjustment portion (704) at a position where the balance adjustment portion cancels a centrifugal force generated by the balance weight (see ¶44 - ¶48).
Yamashita does not teach the scroll electric compressor, wherein “the stacking steel plates have weight portions, respectively, that are formed by reducing a radial dimension of at least one of the flow holes as compared to a radial dimension of the other of the flow holes that overlaps the balance weight in the axial direction, and the balance adjustment portion is formed by stacking the weight portions in the axial direction”.
However, Lifson teaches a scroll compressor wherein a rotor (28) of a motor (25) is formed with holes (32a, 32b) that counteract imbalance force caused by the orbiting movement of the orbiting scroll (24). Lifson further states (see col. 2, lines 38-57) “The use of these options allows the scroll compressor designer the ability to carefully design the amount of material which is removed, and the location of the removed material as required by a particular application”.
Yamashita teaches a rotor with fluid flow holes that extend axially through the rotor. Lifson teaches removing material at selected circumferential locations in the rotor in the form of axial holes in order to cancel a centrifugal force generated by the balance weight. It would have been obvious to the person of ordinary skill in the art before the effective filing date of the invention to have modified the system of canceling a centrifugal force generated by the balance weight taught by Yamashita by dispensing of the rotor weight and removing material at selected circumferential locations as taught by Lifson in order to provide a simpler way of canceling a centrifugal force generated by the balance weight and at the same time reducing the overall weight of the compressor. Applicant should note that forming the weight portions by reducing at least a radial dimension of at least one of the flow holes as compared to a radial dimension of the other flow holes is well within the teachings of Lifson, since Lifson teaches selective removing of material. Further, forming the weight portions by reducing at least a radial dimension of at least one of the flow holes as compared to a radial dimension of the other flow holes is an obvious matter of design choice as long as the removing of material results in the canceling of centrifugal force generated by the balance weight.
Furthermore, it would have been an obvious matter of design choice to adapt the necessary fluid flow holes of Yamashita to perform the integrate balancing function of Lifson. Instead of drilling entirely separate, dedicated holes like Lifson, the designer would simply: modify the existing fluid flow holes {adjust the size/shape of the existing fluid flow holes in the rotor laminations} and create asymmetry {increase the volume of material in the desired circumferential location (opposite the shaft balance weight 33) by reducing the radial dimension of the fluid flow holes in that area, as compared to the other holes. This reduction leaves more mass (the weight portion) and creates the overall balance adjustment portion}. This combination seamlessly integrates Lifson’s asymmetrical balancing principle into Yamashita’s existing fluid-handling structure, resulting in a design that is both balanced and compact, thereby meeting the object of both references. As evidenced by Defranciscis, (see ¶34) “In an embodiment, the rotor 4 has a plurality of holes 6. In an embodiment, these holes 6 allow to optimize both the rotor 4 weight and cooling. One example of patter of holes 6 is shown in FIG. 2. Accordingly, other patterns of holes 6 may be applied to the rotor 4, following design optimization. Indeed, in the embodiment shown in FIG. 1 both the rotor 4 and electromagnets 2 are designed to be passively gas cooled. In other embodiments, not shown in the drawings, the rotor 4 and the electromagnets 2 are designed to be actively gas cooled or liquid cooled”.
Thus, Yamashita, as modified, teaches the scroll electric compressor, wherein “the stacking steel plates have weight portions, respectively, that are formed by reducing a radial dimension of at least one of the flow holes as compared to a radial dimension of the other of the flow holes that overlaps the balance weight in the axial direction, and the balance adjustment portion is formed by stacking the weight portions in the axial direction”.
In reference to claim 2, Yamashita, as modified, teaches the scroll electric compressor, wherein
the rotor (7b; of Yamashita) is integrated into the rotary shaft (5; of Yamashita) by shrink-fitting (see ¶48 of Yamashita), and
the fluid flow holes (77a-77e; of Yamashita) each have an elongated hole shape extending in an arc shape in the circumferential direction of the rotor (as evident from figs. 4 and 5 of Yamashita), radially inner surfaces of the fluid flow holes each extend along an imaginary circle extending in the circumferential direction with an axial line (line of axis “O”) of the rotary shaft as a center (as evident from fig. 4 of Yamashita).
Yamashita, as modified, remains silent on the scroll electric compressor wherein “at least one of the fluid flow holes disposed inside the balance adjustment portion in the radial direction has a radially outer surface that is positioned inside relative to a radially outer surface of the other of the fluid flow holes, in the radial direction, that overlaps the balance weight in the axial direction”.
Yamashita teaches the functionally required holes (77a-77e) and the need for compact rotor. Lifson teaches asymmetrical material removal (creating a “negative weight portion”) as the balancing solution. Defranciscis further evidences (see ¶34) that other patterns of holes (optimize for both rotor weight and cooling) may be applied to the rotor 4, following design optimization. The specific geometries (concentric inner arcs and a smaller radial dimension for some holes) are merely the standard, non-inventing means by which a designer of electric motor laminations would execute the combined function (fluid flow + internal balancing) while respecting the core magnet structure. Creating a smaller radial dimension for some holes is the logical way to create the required “weight portion” in the laminated core. Thus, it would have been obvious to the person of ordinary skill in the art before the effective filing date of the invention to have “at least one of the fluid flow holes disposed inside the balance adjustment portion in the radial direction has a radially outer surface that is positioned inside relative to a radially outer surface of the other of the fluid flow holes, in the radial direction, that overlaps the balance weight in the axial direction” in the modified scroll electric compressor of Yamashita as a matter of design choice since such a modification would have involve a change in shape of the components (in this case, at least one of the fluid flow holes). A change in shape is generally recognized as being within the level of ordinary skill in the art. In re Dailey, 357 F.2d 669, 149 USPQ 47 (CCPA 1966).
In reference to claim 3, Yamashita, as modified, teaches the scroll electric compressor, wherein the balance adjustment portion is formed by stacking the weight portions in the rotor in the axial direction. As noted above in the rejection of claim 1, the rotor weight of Yamashita would be eliminated in the combination with Lifson which will result in in the balance adjustment portion being formed by stacking the weight portions in the entire rotor in the axial direction.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Yamashita in view of Lifson, Defranciscis (evidentiary reference) and further evidenced by Chen et al. (US 2021/0391762 – herein after Chen).
Yamashita, as modified, teaches the scroll electric compressor, wherein the balance adjustment portion is formed by stacking the weight portions in the rotor in the axial direction.
Yamashita, as modified, teaches the scroll electric compressor, wherein the balance adjustment portion is formed by stacking the weight portions in a portion of the rotor in the axial direction.
If the counterbalance required is not a simple moment about the center but a more complex force distribution (or if cost/material saving is prioritized), the designer may choose to stack the heavier, modified plates only in a portion of the axial length and use lighter, less complex plates for the remainder. This selective stacking is well-known, high-precision balancing technique common in rotor design for tailoring the dynamic balance. Chen evidences the stacking of heavier and lighter plates to form the rotor (see fig. 2: “heavier plates” = 105 and “lighter plates” = 103+104 {these plates have more material removed compared to plates 105}). Thus, it would have been obvious to the person of ordinary skill in the art before the effective filing date of the invention to have “wherein the balance adjustment portion is formed by stacking the weight portions in a portion of the rotor in the axial direction” in the modified scroll electric compressor of Yamashita as a matter of design choice to achieve the desired balance between optimal dynamic balance and reduced manufacturing expense.
Response to Arguments
Applicant's arguments filed 01/16/2026 have been fully considered but they are not persuasive.
The Applicant’s argument (pages 7-9) that the proposed modification changes Yamashita’s “principle of operation” or renders it “unsuitable for its intended use” is not persuasive. The principle of operation of Yamashita is an electric scroll compressor that utilizes axial introduction passages in the rotor to move refrigerant while maintaining a compact housing. The proposed modification maintains this fundamental operation; it merely optimized the geometry of the existing flow passages to incorporate an internal balancing function. White Yamashita notes that a larger flow area in the first passages reduces pressure drop, a person of ordinary skill in the art would recognize that engineering often requires balancing competing objectives. Yamashita explicitly identifies (see ¶9, ¶11) “compactness” as a primary goal for vehicle mounting. Using Lifson’s teaching of asymmetric material removal within the rotor allows for the elimination of external balance weights, directly advancing Yamashita’s stated goal of compact design. A person of ordinary skill in the art would find the trade-off of a minor increase in flow resistance in a single passage a predictable and acceptable compromise to achieve a lighter, more compact compressor. A reference does not “teach away” simply because a modification results in a design that is less than optimal in one specific parameter (flow rate), provided the modified structure still performs the required function. The modified Yamashita compressor still functions to compress refrigerant and move the refrigerant through the rotor; it simply does so with a rotor that is internally balanced according to the principles of Lifson. Forming “weight portions” by reducing the radial dimension of existing holes is a routine application of Lifson’s material removal principle to Yamashita’s specific hole pattern. Furthermore, a person of ordinary skill in the art would prioritize and maintain the recited relationship where the total flow passage sectional area of the first passages (771) remains greater than the flow passage sectional area of the second passage (772). Maintaining this hierarchy is a matter of routine design choice and optimization; the designer would logically calibrate the reduction in the radial dimension of the “weight portion” hole(s) to achieve the required mass asymmetry for balancing while ensuring the aggregate area of the remaining passages still satisfies the operational flow requirements established in Yamashita. This integration represents a standard engineering trade-off that preserves the functional operation of the passages while simultaneously achieving the desired internal balance.
The Applicant’s assertion (pages 9-10) that Lifson “teaches away” from the proposed modification is not persuasive. The assertion is based on a misinterpretation of the reference’s distinction from the prior art. While Lifson notes that prior art cooling holes were “symmetrically located” and thus “not applicable” to its own invention, this statement does not discourage the use of holes for balancing. On the contrary, Lifson provides the explicit motivation to move away from symmetry by removing material asymmetrically to counteract force imbalances. Yamashita describes introduction passages (77a-77e) that are equiangularly and thus symmetrically arranged. The Examiner’s proposed modification simply applies Lifson’s principle of asymmetric material removal to Yamashita’s existing structure – specifically by reducing the radial dimension of a select flow hole to create the necessary mass asymmetry. Lifson’s distinction from symmetric holes actually serves as a directive for a person of ordinary skill in the art to modify Yamashita’s symmetric layout into an asymmetric configuration to achieve integrated internal balancing. Therefore, Lifson supports, rather than teaches away from, the combination.
The Applicant’s arguments (page 10) regarding “removing material” vs. “reducing radial dimension” are not persuasive. The Applicant’s argument that Lifson’s teaching of “removing material” can only result in increasing the size of holes, and therefore fails to suggest “reducing a radial dimension” is a formalistic distinction that does not reflect the technical reality of rotor manufacturing. In the context of Yamashita, the rotor is formed by stacking steel plates that have flow holes. A person of ordinary skill in the art understands the dimensions of these holes are determined by the specific amount of material removed (e.g., stamped) from each lamination during fabrication. Lifson teaches that the designer has the “ability to carefully design the amount of material which is removed” to meet specific application requirements. To achieve the asymmetric balancing taught by Lifson within Yamashita’s existing rotor structure, a person of ordinary skill in the art would logically choose to remove less material from the specific area intended to act as the “weight portion” compared to other flow holes. Removing less material from a lamination at a specific circumferential location inherently results in a hole with a “reduced radial dimension” relative to others. This residual mass (the weight portion) provides the necessary centrifugal force to cancel the imbalance of the orbiting scroll. Furthermore, Defranciscis provides evidentiary support that hole patterns in a rotor are routinely modified and optimized to balance rotor weight and cooling requirements.
The Applicant’s arguments (page 11) regarding dependent claims 2 – 4 are not persuasive because independent claim 1 remains rejected and the corresponding presented arguments for claim 1 are not found to be persuasive for reasons discussed above.
Conclusion
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 nonprovisional extension fee (37 CFR 1.17(a)) 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.
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/CHIRAG JARIWALA/Examiner, Art Unit 3746
/BRYAN M LETTMAN/Primary Examiner, Art Unit 3746
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