DETAILED ACTION
Amended claims filed 13 May 2026have been entered. Claims 1, 5, 7-0, and 11-13 remain pending.
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, 5, 7-9, 11, and 13 are rejected under 35 U.S.C. 103 as being unpatentable over Lin (US 2020/0149540).
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Lin fig 1
Claim 1, Lin discloses a centrifugal pump (abstract) comprising:
a rotating body (fig 1, impeller 17, and shaft 12 and axial thrust reducing ring 124) including a rotor blade (fig 1 depicts the impeller blades internal to the impeller, par 0026);
a back plate (labyrinth 18) disposed at a back side (18 is behind the backplane 172 of the impeller 17, par 0026) of the rotating body to prevent disturbance of exhaust gas (fig 2 and fig 3, labyrinth seal 18 faces 124 and controls gas leakage exhausting from the impeller, par 0025, 0032, 0049);
a rotor shaft (12) disposed in a center of the rotating body;
a magnetic bearing (magnetic bearing 131 and 133 acting on shaft 12, par 0027) configured to levitate and support the rotor shaft (par 0004);
a touchdown bearing (14, par 0025, 0030) that is separated, by an axial gap (fig 2, gaps c3, c4, par 0029-0031), from the rotor shaft and configured to support the rotor shaft when the magnetic bearing is uncontrollable (touchdown bearing supports the spindle/shaft 12 when the magnetic bearing par 0030-0031; specifically, because touchdown bearing clearance c9 and c10 are smaller than the first radial bearing clearance c7);
and a bearing protection structure (teeth of labyrinth seal 18, par 0012, 0045, 0058; examiner notes that this is in accord with applicant’s disclosure of protrusions as a labyrinth, applicant’s fig 13, par 0077) configured to protect the touchdown bearing (abnormal element contact at the labyrinth ring is a known problem, par 0012, 0036, 0060; examiner notes that this is in accord with applicant’s disclosure; bearing protection structure is a protrusion that contacts the backplate during uncontrolled operation, par 0040, 0072; applicant’s protection results from the protrusion striking the rotating body before the touchdown bearing, Applicant’s par 0040; therefore a labyrinth seal which contact the rotor can meet the claimed limitation), wherein the bearing protection structure includes a protrusion (labyrinth seal teeth, par 0012) disposed on at least one of the rotating body (1st of two claimed alternatives) and the back plate (2nd of two claimed alternatives; teeth are on labyrinth seal 18), the protrusion extending along an axial direction of the centrifugal pump (fig 2, 18 extends axially) and having a first end (base of seal tooth) and a second end (tip of seal tooth), the first end being connected to the one of the rotating body (1st of two claimed alternatives) and the back plate (2nd of two claimed alternatives, labyrinth seal 18 is connected to the base of the seal teeth), the second end (tip of the seal tooth) facing the other of the rotating body and the back plate (fig 1, tip of seal tooth faces the ring 124 of the rotating body) in the axial direction of the centrifugal pump (fig 2, the teeth face the thrust-reducing ring 124 axially along the conic gap c5; since the labyrinth seal and the axial thrust reducing ring 124 meet in a conic shape, they overlap and face each other axially),
upon touchdown of the rotor shaft on the touchdown bearing (shaft 12 on touchdown bearing 14, par 0031), the other of the rotating body (the rotating body would come into contact with the teeth) and the back plate comes into contact with the second end (reasonably the rotating body 124 comes into contact with the teeth 18 during abnormal contact; abnormal element contact between the labyrinth seal/ring 18 and the axial thrust reducing ring 124 is recognized as a problem that sometimes occurs during abnormalities, par 0012, 0036, 0060) so that kinetic energy of the rotating body acting on the touchdown bearing is reduced (inherently kinetic energy of a first object is reduced as it collides with a second object because some of that kinetic energy is transferred to the second object), and
when no touchdown occurs, an axial clearance is present between the second end of the protrusion and the other of the rotating body and the back plate (fig 2, axial clearance c5).
Lin is silent on the axial clearance being greater than the axial gap between the touchdown bearing and the rotor shaft (fig 2, axial gaps c3 and c4; par 0030).
Nevertheless, the axial clearance (c5) between the labyrinth seal 18 and the axial thrust reducing ring 124 being greater than axial gap C3 is obvious as a result effective variable in order to control gas leakage (par 0049). The courts have held that result-effective variables are obvious when there is a motivation to optimize (In re Antoine, 559 F.2d 618, 195 USPQ 6 (CCPA 1977)). In this case, the claimed values can be used for these result effective variables, in order to control gas leakage because Lin teaches reducing the clearance of c3 in order to increase the clearance of c5 (Lin, par 0049). Furthermore, it is obvious from the layout in fig 2, that the conical shape of seal gap C5 only constrains axial movement of the shaft in one direction; where the axial movement of the shaft is constrained by gap c3 is the other direction. Therefore, when axial movement is constrained by gap c3 and not by conic gap c5, conic gap c5 must be larger than gap c3.
Claim 5, Lin teaches the centrifugal pump according to claim 1. Lin is silent on wherein a storage portion is disposed at a position downstream of the protrusion to store contaminants created on contact between the rotating body and the back plate.
Nevertheless, reasonably if abnormal contact did occur between labyrinth seal 18 and axial thrust reducing ring 124; gas leaking through toward the motor internals would also carry any broken pieces into the interior of the motor. Fig 1 shows several spaces between shaft 12 and the interior of the case which could accumulate material carried in by leaking gas.
Claim 7, Lin teaches the centrifugal pump according to claim 1, wherein the protrusion is provided in plurality (fig 2 shows several teeth on labyrinth 18), and
as viewed from the axial direction of the centrifugal pump, the plurality of protrusions are arranged dispersedly at regular intervals in a circumferential direction (teeth have a constant diameter encircling the saft, par 0034, 0041).
Claim 8, Lin teaches the centrifugal pump according to claim 1, wherein the protrusion (labyrinth teeth) has a surface that has a lower friction property (under a BRI teeth have a smaller / narrower surface area than the flat surface of 18, and of ring 124; inherently a lower surface area produces less friction than a higher surface area of the same material; examiner notes that applicant does not disclose the specific friction property claimed; surface area is known in the art characteristic used to calculate the friction resistance of a surface) than those of the rotating body (124) and the back plate (18).
Claim 9, Lin discloses a centrifugal pump bearing protection structure (teeth of labyrinth seal 18, par 0012, 0045, 0058; examiner notes that this is in accord with applicant’s disclosure of protrusions as a labyrinth, applicant’s fig 13, par 0077) to be used in a centrifugal pump (abstract) to protect a touchdown bearing (14, par 0025, 0030), wherein the centrifugal pump includes: a rotating body (fig 1, impeller 17, and shaft 12 and axial thrust reducing ring 124) including a rotor blade (fig 1, impeller 17 with impeller blades, par 0026); a back plate (labyrinth 18) disposed at a back side (18 is behind backplane 172 of impeller 17, par 0026) of the rotating body to prevent disturbance of exhaust gas (fig 2 and fig 3, labyrinth seal 18 faces 124 and controls gas leakage exhausting from the impeller, par 0025, 0032, 0049);
a rotor shaft (12) disposed in a center of the rotating body; a magnetic bearing (131, 133, par 0027) that levitates and supports the rotor shaft (par 0004); and the touchdown bearing that is separated, by an axial gap (gaps c3, c4, par 0029-0031), from the rotor shaft and supports the rotor shaft when the magnetic bearing is uncontrollable (touchdown bearing supports the spindle/shaft 12 when the magnetic bearing par 0030-0031; specifically because touchdown bearing clearance c9 and c10 are smaller than the first radial bearing clearance c7),
the bearing protection structure includes a protrusion (teeth of labyrinth seal 18, par 0012, 0045, 0058) disposed on at least one of the rotating body and the back plate (teeth are on labyrinth seal 18, par 0012), the protrusion extending along an axial direction (18 extends axially) of the centrifugal pump and having a first end (base of tooth) and a second end (tip of tooth), the first end being connected to the one of the rotating body and the back plate (2nd of two claimed alternatives, labyrinth seal 18 is connected to the base of the seal teeth), the second end (tip of tooth) facing the other of the rotating body and the back plate in the axial direction of the centrifugal pump (tooth faces the ring 124 of the rotating body; fig 2, the teeth face the thrust-reducing ring 124 axially along the conic gap c5; since the labyrinth seal and the axial thrust reducing ring 124 meet in a conic shape, they overlap and face each other axially),
upon touchdown of the rotor shaft on the touchdown bearing (shaft 12 on touchdown bearing 14, par 0031), the other of the rotating body and the back plate comes into contact with the second end (reasonably the rotating body 124 comes into contact with the teeth 18 during abnormal contact; abnormal element contact between the labyrinth seal/ring 18 and the axial thrust reducing ring 124 is recognized as a problem that sometimes occurs during abnormalities, par 0012, 0036, 0060) so that kinetic energy of the rotating body acting on the touchdown bearing is reduced (inherently kinetic energy of a first object is reduced as it collides with a second object because some of that kinetic energy is transferred to the second object), and when no touchdown occurs, an axial clearance is present between the second end of the protrusion and the other of the rotating body and the back plate (fig 2, axial clearance c5).
Lim is silent on the axial clearance being greater than the axial gap between the touchdown bearing and the rotor shaft.
Nevertheless, the axial clearance (c5) between the labyrinth seal 18 and the axial thrust reducing ring 124 being greater than axial gap C3 is obvious as a result effective variable in order to control gas leakage (par 0049). The courts have held that result-effective variables are obvious when there is a motivation to optimize (In re Antoine, 559 F.2d 618, 195 USPQ 6 (CCPA 1977)). In this case, the claimed values can be used for these result effective variables, in order to control gas leakage because Lin teaches reducing the clearance of c3 in order to increase the clearance of c5 (Lin, par 0049). Furthermore, it is obvious from the layout in fig 2, that the conical shape of seal gap C5 only constrains axial movement of the shaft in one direction; where the axial movement of the shaft is constrained by gap c3 is the other direction. Therefore, when axial movement is constrained by gap c3 and not by conic gap c5, conic gap c5 must be larger than gap c3.
Claim 11 Lim teaches the centrifugal pump according to claim 1. Lim is silent on wherein the axial clearance between the second end of the protrusion and the other of the rotating body and the back plate is smaller (fig 3A, c6 = 0.15mm, par 0039) than a value obtained by adding the axial gap between the touchdown bearing and the rotor shaft (fig 2, touchdown bearing clearance with shaft c9, par 0029) to an axial internal gap of the touchdown bearing (fig 2, C3 is an axial internal gap that increases in size as c5 / c6 becomes smaller, par 0049).
Nevertheless, the axial clearance (c5) between the labyrinth seal 18 and the axial thrust reducing ring 124 being greater than axial gap C3 is obvious as a result effective variable in order to control gas leakage (par 0049). The courts have held that result-effective variables are obvious when there is a motivation to optimize (In re Antoine, 559 F.2d 618, 195 USPQ 6 (CCPA 1977)). In this case, the claimed values can be used for these result effective variables, in order to control gas leakage because Lin teaches increasing the clearance of c3 in order to reduce the clearance of c5 (Lin, par 0049). Furthermore, it is obvious from the layout in fig 2, that the conical shape of seal gap C5 only constrains axial movement of the shaft in one direction; where the axial movement of the shaft is constrained by gap c3 is the other direction. Therefore, when axial movement is constrained by conic gap c5 and not by gap c3, gap c3 must be larger than gap c5. Furthermore, since gap c3 is already larger than gap c5, adding gap c3 to gap c9 will result in a value larger than gap c5 no matter the size of gap c9. Therefore, making obvious the relative claimed values.
Claim 13, Lim teaches the centrifugal pump according to claim 1, wherein the back plate has an inner circumference side that is recessed as compared with an outer circumference side of the back plate (fig 2 shows that labyrinth seal 18 has an inner diameter surface and an outer diameter surface, the inner diameter is recessed by the grooves between labyrinth teeth), the inner circumference side of the back plate is positioned on the back side of the rotating body (labyrinth 18 is on the backside of impeller 172), and the protrusion is disposed on the inner circumference side of the back plate (labyrinth teeth are on the inner circumference of the labyrinth).
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Lin in view of Alban (EP 2749771, provided in previous office action).
Claim 12, Lin teaches the centrifugal pump according to claim 1. Lin is silent wherein the rotating body is provided in multiple stages, and in a first stage, which is an inlet side among the multiple stages, the protrusion is disposed on the at least one of the rotating body and the back plate.
Alban teaches an analogous multistage centrifugal pump with seals and magnetic bearings where the seals aid with axial load balancing (fig 1-4, par 001; bladed hub 4, par 0032, magnetic bearing, par 0087; seals 21, 23, 20, par 0076-0078, 0061-0062).
It would have been obvious to a person of ordinary skill in the art prior to the effective filing date of the claimed invention to configure the single stage of Lin into a multi stage rotating machine by adding successive impeller wheels, and seals as taught by Alban, thereby increasing the maximum pressure of the compressor.
Furthermore, since each multiple stage of the combination includes a labyrinth seal in order to aid axial balancing, then a first stage at the inlet and all subsequent stages would include the labyrinth tooth protrusion disposed on each respective back plate (18).
Response to Arguments
Applicant’s arguments with respect to claims 1, 5, 7-9, and 11-13 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Conclusion
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 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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to GEOFFREY S LEE whose telephone number is (571)272-5354. The examiner can normally be reached Mon-Fri 0900-1800.
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/GEOFFREY S LEE/ Examiner, Art Unit 3746
/DOMINICK L PLAKKOOTTAM/ Primary Examiner, Art Unit 3746
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