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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 12/4/2025 has been entered.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim 1-5, 7-11 and 13-15 are rejected under 35 U.S.C. 103 as being unpatentable over Anspann et al. (DE 102012022452 A1) in light of Greiter (US 20240333104 A1) and further in light of Weber (DE 102021128068, citations to US 2024/0333103 as English language equivalent).
With regard to claim 1, Anspann et al. teaches “A stator assembly for an electric machine, comprising:
a housing,
a stator (Anspann et al., Fig. 1 at 32, Anspann Machine Translation Paragraph [0068]) disposed in the housing, the stator having a stator core (Anspann et al., Fig. 1 at 36, Anspann Machine Translation Paragraph [0069]) and stator windings (Anspann et al., Fig. 1 at 40, Anspann Machine Translation Paragraph [0069]); and
a cooling system for cooling the stator (Anspann et al., Fig. 1 at 50, Anspann Machine Translation Paragraph [0073]),
wherein the cooling system includes a cooling shell at least partially encompassing the stator core and thermally coupled to the stator core (Anspann et al., Fig. 1, 3-6 at 64; Anspann Machine Translation Paragraph [0075] “the cooling channels 64 are each formed between an inner peripheral portion of the machine housing 28 and an outer peripheral portion of the stator core 36. As a result, heat generated in the stator 32 can be efficiently absorbed by a cooling fluid flowing through the cooling channels.”),
wherein the cooling system has a supply line connected to the cooling shell at an intake end (Anspann et al., Fig. 1 left side, see 68, feed channel) and a return line connected to the cooling shell at an outlet end (Fig. 1 at 70),
wherein the cooling system has at least one coolant pump (Anspann et al., Fig. 1 at 56) and at least one coolant container (Anspann et al., Fig. 1 at 54), . . .
wherein the cooling shell is formed by a plurality of cooling channels (Anspann et al., Figs. 5-6 at 64a-64h) that extend in an axial direction of the stator core (Anspann et al., Figs. 1, 6),
wherein the cooling channels are connected to the supply line (Anspann et al., Figs. 1, 6, at 68) in the flow path at a first axial end surface of the stator core through a first annular channel (Anspann et al., Figs. 1, 6, at 92; Anspann Machine Translation, Paragraphs [0087], [0102]), and
wherein the cooling channels are connected to the return line (Anspann, Figs. 1, 6, at 70) in the flow path at a second axial end surface of the stator core through a second annular channel (Anspann et al., Figs. 1, 6, at 94), and
wherein the plurality of cooling channels are each configured to direct a unidirectional flow of the coolant in the axial direction from the first annular channel towards the second annular channel (Anspann, Fig. 5-6 at 64f; Anspann Machine Translation, Paragraphs [0087], [0102], [0107]: Anspann teaches that multiple cooling channels may be connected in parallel to a single supply channel, and that the cooling channels need not be connected to each other in a meander arrangement).”
Anspann et al. does not explicitly teach
“wherein the coolant pump is connected to the supply line in a flow path between the coolant container and the cooling shell in order to supply coolant to the cooling shell through the supply line, and
wherein the return line is connected in the flow path between the coolant container and the coolant pump such that the coolant pump is supplied with coolant from the return line.”
Greiter teaches “wherein the coolant pump (Greiter, Fig. 1, Paragraph [0033]-[0034]: The coolant pump is located on the left side of figure 1, indicated by a circle with two diagonal lines. It appears that the reference numeral was omitted from Fig. 1, but a similar structure is indicated by reference numeral 64 in Fig. 2) is connected to the supply line (Greiter, Fig. 1 at 73, 74, and 41); in a flow path between the coolant container (Greiter, Fig. 1 at 61, Paragraph [0037]-[0038]: “the oil collects at the bottom of the rotor chamber, from which it is led into a second return line 73 via rotor chamber drain points 79.” Examiner notes that the coolant container (reservoir) of Anspann 54 may be a “fluid sump of the transmission housing,” Anspann Machine Translation at Paragraph [0077], which may be part of the machine housing. Anspann Machine Translation at Paragraph [0067]. In both Anspann et al. and Greiter, the coolant container is the container formed by the housing where the coolant sprayed to cool the electric machine collects.) and the cooling shell (Anspann et al., Fig. 1, 3-6 at 64, Greiter Fig. 1 at 59) in order to supply coolant to the cooling shell through the supply line, and
wherein the return line (Greiter, Fig. 1 at 72), is connected in the flow path between the coolant container (Greiter, Fig. 1 at 61) and the coolant pump (Greiter, Fig. 1, see above) such that the coolant pump is supplied with coolant from the return line (Greiter, Fig. 1, Paragraph [0035], [0038]: “The stator chamber drain point 71 also has a flow connection via a first return line 72 to the oil column 65 . . . into which the first return line opens. . . . In addition, a suction line is connected to the suction side of the dual pump 64 which is fluidically connected to the oil column.”) Examiner notes that the return line is interpreted to be the line 72 in Fig. 1 of Greiter, which leads from the stator cooling jacket to the oil column 65.
It would have been obvious to a person of skill in the art to provide a return line as shown in Greiter (Greiter, Fig. 1 at 72) to the second annular ring of Anspann (Anspann, Fig. 1 at 94) in order to increase the coolant flow speed and improve cooling in the stator cooling jacket while maintaining a proper amount of fluid flowing through the winding head shower provided through the holes in the annular rings of Anspann (Anspann, Fig. 1 at 92, 94, 100). Anspann shows a return (Anspann, Figs. 1,6 at 70) from the ring, but is not clear as to whether there is a line or if the coolant exits only through the winding head shower in the annular rings (Anspann, Fig. 1 at 92, 94, 100). However, by providing the return line (Greiter, Fig. 1 at 72), a person of skill in the art could increase the flow speed of the coolant, thereby increasing the cooling through the stator cooling jacket, while not providing unnecessary coolant to the winding head shower. A person having ordinary skill in the art would recognize the benefits of increasing the cooling ability of the cooling jacket while also minimizing the coolant in the motor chamber or sump, as taught by Greiter (Greiter, Paragraph [0031]: “The invention keeps the coolant largely out of the rotor chamber.”), and would therefore be motivated to use the teachings of the cooling circuit of Greiter with the cooling jacket of Anspann.
It would further have been obvious to a person having ordinary skill in the art at the time of filing to combine the teachings of Anspann et al. with those of Greiter in order to apply a dry sump system to the motor of Anspann et al. In order to do so, a person of skill in the art would provide a coolant tank (Greiter, Fig. 1 at 63, 65), in addition to the coolant container of Anspann (Anspann, Fig. 1 at 54, Greiter, Fig. 1 at 61). By storing the coolant mainly in the separate coolant tank (Greiter, Fig. 1 at 63, 65) while minimizing the coolant stored in the sump or coolant container (Anspann, Fig. 1 at 54), a person of skill in the art would prevent large amounts of coolant from collecting in the motor chamber and interfering with the operation of the motor by creating drag on the rotor. In addition, where the coolant container of Anspann (Fig. 1 at 54) is a sump, it must extend the full length of the rotor and stator in order to collect coolant which may be sprayed by both the holes providing coolant to the winding heads (Anspann, Fig. 1 at 100) and from holes in the rotor itself (Anspann, Fig. 1 at 78, 86). This results in a wide container which may be affected greatly by coolant sloshing around due to the movement of a vehicle. When coolant flow is provided directly from this tank to the cooling system, a reliable coolant flow may be difficult to ensure. In contrast, a separate coolant tank may be designed to minimize the effects of sloshing on coolant flow (by being a tall shape, for example, with a suction line provided deep in the oil column, as shown in Greiter). A person of ordinary skill in the art would be motivated to add the coolant tank (Greiter, Fig. 1 at 63, 65) and cooling lines (Greiter, Fig. 1 at 72-74, 41) of Greiter to the cooling system of Anspann in order to deal with these problems by creating a system similar to that of a dry sump system and minimizing the coolant stored in coolant container (the sump in or below the motor chamber), while providing another tank to provide a consistent input into the coolant system.
In order to fully realize the benefits of a dry sump system, a person of skill in the art would find it obvious to connect the return line (Greiter, Fig. 1 at 72) at a suction point in the supply line between the coolant container and the cooling jacket (Greiter, Fig. 1 at 63, 65), as taught by Greiter (in this case, into the cooling tank). A person of skill in the art would be motivated to do this instead of connecting the return line directly to the coolant container (Anspann, Fig. 1 at 54, Greiter, Fig. 1 at 61) as shown by Anspann, in order to further minimize the amount of coolant that collects in the sump or coolant container. This would help provide the benefits of a dry sump system to the cooling system of Anspann, including at least the minimization of the effects of coolant sloshing and minimizing the effects of coolant drag on the motor.
A person of skill in the art would combine the teachings of Greiter with those of Anspann et al. in order to provide faster coolant speeds through the stator cooling jacket while maintaining an appropriate level of cooling flow through the winding head shower. A person of skill in the art would further be motivated to combine the teachings of Greiter with those of Anspann et al. in order to provide a dry sump cooling system to the motor of Anspann, providing the known benefits of such a system.
Anspann et al. and Greiter fail to explicitly teach that the at least one coolant container is disposed outside the stator housing.
Weber teaches a stator assembly for an electric machine (figure 1) comprising a housing (stator housing 2), a stator (4) disposed in the stator housing (2), the stator having a stator core and stator windings (21); and a cooling system for cooling the stator (35, 37, 41, 43, 44, 46) wherein the cooling system has at least one coolant pump (56, 59) and at least one coolant container(55) disposed outside the housing (figure 1 illustrates an underlying stator housing sump 55 on the bottom side of the stator housing which allows coolant to flow through two drain openings 54 fluidly connecting the discrete housings, para. [0021]).
It would have been obvious to a person of skill in the art at the time the invention was filed to modify the stator housing of Anspann et al. and Greiter to include a distinct, fluidly connected sump housing, as taught by Weber, in order to provide more reliable return of the coolant t the coolant tank while maneuvering the vehicle (Weber, para. [0025]). Accordingly, a person of skill in the art would provide the coolant container of Anspann et al. and Greiter in the form of a separate sump housing at the bottom of the stator housing.
Claim 1 is therefore obvious under the combination of Anspann et al., Greiter and Weber.
With regard to claim 2, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. The combination of Anspann et al., Greiter and Weber further teaches “wherein a supply flow path runs from the coolant container (Anspann et al. Fig. 1 at 54, Greiter Fig. 1 at 61) through the supply line (Greiter Fig. 1 at 73, 74, and 41) to an intake in the cooling shell (Greiter Fig. 1 at 69) and wherein a return flow path runs from an outlet in the cooling shell (Greiter Fig. 1 at 71) through the return line (Greiter, Fig. 1 at 72) and ends in the supply flow path.” Examiner notes that the supply flow path flows from the Container (Greiter, Fig. 1 at 61), through the “second return line” (Greiter, Fig. 1 at 73), through the pump and the riser line (Greiter, Fig. 1 at 66) into the oil column (Greiter, Fig. 1 at 65). From there, the supply flow path flows through the suction line (Greiter, Fig. 1 at 74), through the other side of the pump into the supply line (Greiter, Fig. 1 at 41) into the cooling shell (Greiter, Fig. 1 at 59). The return flow path flows from the cooling shell (Greiter Fig. 1 at 69) through the first return line (Greiter Fig. 1 at 72), into the oil column (Greiter, Fig. 1 at 65). The flow path is a result of the structure described in claim 1 and as a such would be obvious to a person of ordinary skill in the art for the same reasons described in claim 1.
With regard to claim 3, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Greiter further teaches “wherein the return line (Greiter, Fig. 1 at 72) opens into or adjacent to the coolant pump (Greiter, Fig. 1) at a suction point (Greiter, Fig. 1 at 74, Paragraphs [0035], [0038]; The return line 72 opens into the oil column 65, which is fluidically connected to the suction line 74 and the suction side of the dual pump.).” A person of ordinary skill in the art would be motivated to have the return line open near the suction point in order to allow the oil flowing through the return line to supply oil to the pump and to the cooling jacket.
With regard to claim 4, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Greiter further teaches “wherein the cooling system includes a coolant tank (Greiter, Fig. 1 at 63, 65, Paragraph [0033]) that is connected in the flow path between the coolant container (Greiter, Fig. 1 at 61) and the coolant pump (Greiter, Fig. 1 at 64), and wherein the return line (Greiter Fig. 1 at 72) opens into the coolant tank (Greiter, Fig. 1 at 63, 65).” A person having ordinary skill in the art at the time of filing would find it obvious to combine the teachings of Anspann et al. with those of Greiter in order to apply a dry sump system to the motor of Anspann et al. A person of skill in the art would recognize that by providing a coolant tank (Greiter, Fig. 1 at 63, 65), in addition to the coolant container of Anspann (Anspann, Fig. 1 at 54, Greiter, Fig. 1 at 61), the amount of coolant stored in the coolant container or sump located in motor chamber could be minimized. By minimizing the coolant stored in the sump or coolant container (Anspann, Fig. 1 at 54), a person of skill in the art would prevent large amounts of coolant from collecting in the motor chamber and interfering with the operation of the motor by creating drag on the rotor. In addition, providing a separate coolant tank allows the tank to be designed to minimize the effects of sloshing on coolant flow (by being a tall shape, for example, with a suction line provided deep in the oil column, as shown in Greiter Fig. 1), rather than the coolant container (or sump) of Anspann or Greiter (Anspann, Fig. 1 at 54), which must extend the full length of the rotor and stator in order to collect coolant which may be sprayed by both the holes providing coolant to the winding heads (Anspann, Fig. 1 at 100) and from holes in the rotor itself (Anspann, Fig. 1 at 78, 86). This results in a wide container which may be affected greatly by coolant sloshing around due to the movement of a vehicle. A person of ordinary skill in the art would be motivated to add the coolant tank (Greiter, Fig. 1 at 63, 65) and cooling lines (Greiter, Fig. 1 at 72-74, 41) of Greiter to the cooling system of Anspann in order to deal with these problems by creating a system similar to that of a dry sump system and minimizing the coolant stored in coolant container (the sump in or below the motor chamber), while providing another tank to provide a consistent input into the coolant system.
With regard to claim 5, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 4 as described above. Greiter further teaches “wherein the cooling system has a second coolant pump (Greiter Fig. 1, Paragraph [0033]: “In the dual pump 64, the feed and return pumps 37, 56, are driven by an electric motor using a common drive shaft (not shown).” Greiter teaches a system that uses a dual pump combining two separate pumps.), and wherein the second coolant pump is connected to a connecting line (Greiter, Fig. 1 at 73) in the flow path between the coolant container (Greiter, Fig. 1 at 61) and the coolant tank (Greiter, Fig. 1 at 63) in order to supply coolant to the coolant tank through the connecting line.” A person of skill in the art would recognize the necessity of including a second pump in the dry sump system of Greiter as applied to Anspann in claim 4 above and would therefore include the pump when applying Greiter to Anspann.
With regard to claim 7, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Anspann et al. further teaches: “wherein the plurality of cooling channels (Anspann et al., Figs. 1, 5-6 at 64) each have a coolant intake and a coolant outlet (Anspann et al., Figs. 5-6, The coolant intakes and outlets can be seen in Fisg.5- 6 as the locations where coolant enters and leaves the coolant channels) wherein the coolant intakes are connected to one another in the flow path at the first axial end surface through the first annular channel (Anspann et al., Figs. 1, 6 at 92: Figure 1 shows the flow path flowing through the coolant intake 68 in the first annular ring 92 at a first axial end surface of the stator. Fig. 6 shows that the coolant intakes are each connected through the first annular ring 92), and wherein the coolant outlets are connected to one another in the flow path at the second axial end surface through the second annular channel (Anspann et al., Figs 1, 6 at 94: Figure 1 shows the flow path travelling through a coolant outlet 70 from the second annular ring 94 at a second axial end surface of the stator (See also Anspann Machine Translation Paragraph [0088]). Fig. 6 shows that the coolant outlets are each connected through the second annular ring 94).”
With regard to claim 8, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Anspann et al. further teaches: “wherein the first annular channel (Anspann et al., Figs. 1, 6 at 92) is at least partially formed by a first coolant guide ring (Anspann et al., Figs. 1, 6 at 92, Anspann Machine Translation Paragraph [0112]: “Annular channel device”) and the second annular channel (Anspann et al., Figs. 1, 6 at 94) is at least partially formed by a second coolant guide ring (Anspann et al., Figs. 1, 6 at 94, Anspann Machine Translation Paragraph [0112]: “Annular channel device”), wherein the first coolant guide ring is supported on the first axial end surface of the stator core (Anspann et al., Figs. 1, 6-7, Anspann Machine Translation Paragraphs [0117]-[0120]: “The annular channel device 92 has a first annular channel part 123 and a second annular channel part 124 . . . The first ring channel part 123 is rigidly connected to the stator.” Figures 1 and 6-7 also show the coolant guide ring (annular channel device) supported on the axial end surface of the stator core), and wherein the second coolant guide ring is supported on the second axial end surface of the stator core (Anspann et al., Figs. 1, 6-7, Anspann Machine Translation Paragraph [0116]: “It is understood that a corresponding annular channel device can also be provided at another axial end.”).”
With regard to claim 9, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Anspann further teaches “wherein the supply line . . . in an intended installation state of the stator assembly are connected to the cooling shell at an upper surface of the stator core.” Anspann does not explicitly teach that the return line “in an intended installation state of the stator assembly are connected to the cooling shell at an upper surface of the stator core.” However, Greiter teaches that “the return line in an intended installation state of the stator assembly are connected to the cooling shell at an upper surface of the stator core (Greiter Fig. 1, Paragraph [0009]).” Greiter teaches that the outlet being located at the top is to help keep the stator cooling jacket completely filled with oil. As such, a person of ordinary skill in the art would be motivated to install the outlet at the top of the system in order to keep the cooling jacket completely filled with oil and ensure proper cooling of the stator.
With regard to claim 10, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Anspann et al. further teaches that the stator assembly further comprises “a housing (Anspann et al., Fig. 1 at 28), wherein the supply line and/or return line are formed in the housing (Anspann et al., Fig. 1 at 68, Anspann Machine Translation Paragraph [0076]: “The cooling channels 64 are connected to a supply channel 68, which can be formed, for example, in a wall of the machine housing 28.”).” Examiner notes that while the term “and/or” does not make the claim indefinite, it is interpreted using the broadest reasonable interpretation, which in this case means that the claim is obvious if only one or the other of the supply line or return line are formed in the housing.
With regard to claim 11, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Anspann et al. further teaches “wherein the stator windings form at least one winding head adjoining the stator core in the axial direction (Anspann et al., Fig. 1 at 42a, 42b; Anspann Machine Translation Paragraph [0069]), and wherein the cooling system is configured to cool the at least one winding head. (Anspann Machine Translation Paragraph [0083]).”
With regard to claim 13, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 11 as described above. Anspann et al. further teaches “further comprising a first coolant guide ring and a second coolant guide ring (Anspann et al., Figs 1, 6 at 92, 94),” and “wherein the first and/or second coolant guide ring has holes distributed over a circumference (Anspann et al., Figs 1-2, 6-8 at 100), such that a portion of the coolant conveyed in the supply line can be diverted toward the at least one winding head through the holes (Anspann et al., Fig. 1-2, Anspann Machine Translation Paragraph [0092]).”
With regard to claim 14, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 13 as described above. Anspann et al. further teaches “wherein the first and/or second coolant guide rings (Anspann et al., Fig. 1 at 92, 94) are located on a radial outer surface of the at least one winding head (Anspann et al., Fig. 1 at 42a, 42b), and wherein the holes (Anspann et al. Figs. 1, 6-7 at 100) are directed radially toward the winding heads (Anspann et al., Fig. 6-7, Anspann Machine Translation Paragraph [0092]) to form a winding head shower (Anspann Machine Translation, Paragraph [0093]).”
With regard to claim 15, the combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 1 as described above. Anspann et al. further teaches “An electric machine (Anspann et al., Figure 1 showing a rotor and stator together, Anspann Machine Translation Abstract) that has a stator assembly according to claim 1.”
Claims 16 is rejected under 35 U.S.C. 103 as being unpatentable over the combination of Anspann et al., Greiter and Weber as applied to claim 13 above, and further in view of routine optimization as shown by Scharlach (US 20190006908) and Liu et al. (C. Liu et al., "Estimation of Oil Spray Cooling Heat Transfer Coefficients on Hairpin Windings With Reduced-Parameter Models," in IEEE Transactions on Transportation Electrification, vol. 7, no. 2, pp. 793-803, June 2021, doi: 10.1109/TTE.2020.3031373).
The combination of Anspann et al., Greiter and Weber teaches the stator assembly according to claim 13, as described above.
The combination of Anspann et al., Greiter and Weber does not explicitly teach “wherein the holes are configured such that no more than 20% of a volumetric flow in the first and/or second coolant guide ring is diverted for winding head cooling.
However, the amount of volumetric flow would be a matter of routine optimization. A person of ordinary skill in the art would need to consider a number of factors in order to determine the ideal portion of the flow rate to be diverted for winding head cooling. Examiner notes that Anspann et al. shows a return (Anspann et al., Figs. 1 and 6, at 70) which is connected to the second annular channel, which “return[s] the cooling fluid 60 heated in the cooling channels 64 to the reservoir 54.” (Anspann et al. Machine Translation, Paragraph [0088]). As such, Anspann et al. teaches a machine where less than 100% of the coolant is diverted into the spray channels for winding head cooling. A person of ordinary skill in the art would be able to use the teachings of Anspann et al. and optimize the amount of coolant diverted into the spray channels for winding head cooling.
A person of ordinary skill in the art would consider a number of factors to determine the appropriate amount of oil to be used to cool the stator winding heads and therefore the proportion of oil in the coolant system to be used for the winding head cooling. One factor would be the length of the cooling circuit and whether additional components were to be cooled by the cooling circuit. Examiner notes that Scharlach teaches an arrangement wherein the cooling system not only cools the stator and winding heads, but also cools other elements using the same cooling circuit. Scharlach teaches the coolant continuing to pass through a hollow rotor in order to cool the rotor (See e.g. Scharlach, Fig. 1), Scharlach also teaches that some of the coolant is diverted to cool the stator winding heads, and that this coolant is recovered from the bottom of the motor case and not used to cool the additional components (e.g. Scharlach, Fig. 1 at 12). A person of ordinary skill in the art would find it obvious to use the teachings of Scharlach with the system of Anspann et al., Greiter and Weber in order to cool the entire system instead of just the stator, using a single cooling circuit for simplicity. In order to do so, sufficient coolant would have to pass through the second cooling ring and into the additional component to provide effective cooling to the additional component.
Furthermore, Liu et al. (C. Liu et al., "Estimation of Oil Spray Cooling Heat Transfer Coefficients on Hairpin Windings With Reduced-Parameter Models," in IEEE Transactions on Transportation Electrification, vol. 7, no. 2, pp. 793-803, June 2021, doi: 10.1109/TTE.2020.3031373) teaches that the flow rate of the coolant will affect the cooling of the end windings. The flow rate would also affect the percentage of volumetric flow of coolant being used to cool the winding heads. In addition, Greiter teaches that having a minimal amount of oil in the sump is ideal (Greiter, Paragraph [0015]), using a dry sump where the coolant is actively returned. As noted above, a dry sump can help prevent the coolant from causing drag on the rotor. It can also prevent the sloshing of the coolant in the sump from affecting operation of the motor too much. A person of skill in the art would recognize that the amount of coolant in the sump is a function of the flow rate into the sump (determined at least partially by the volumetric flow of the coolant cooling the winding heads), and the flow rate of the coolant out of the sump (determined generally by the flow rate of the pump removing the oil from the sump. In summary, a person of ordinary skill in the art would be aware of a number of considerations when determining what proportion of cooling liquid to use to cool the winding heads, these considerations including the length of the cooling circuit, whether additional components of the motor are to be cooled using the cooling circuit, the desired level of coolant in the sump (encompassing the flow rate of cooling fluid out of the sump and the total flow rate of cooling fluid into the sump), and the amount of cooling fluid needed to effectively cool the winding heads (which depends on at least the current in the winding heads and also on the type of cooling fluid being used). A person of ordinary skill in the art would consider at least these elements in determining the amount of coolant to be used to cool the winding heads and would be capable of determining the appropriate amount without undue experimentation. As such, claim 16 is merely routine optimization of claim 13 and is obvious to a person of ordinary skill in the art.
Response to Arguments
Applicant’s arguments with respect to claim(s) 1-5, 7-11, 13-16 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
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/CHRISTOPHER M KOEHLER/Supervisory Patent Examiner, Art Unit 2834