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 .
Response to Arguments
Applicant has cancelled all previously rejected claims 1-20 and presented new claims 21-40. There are no arguments to respond to. Claims 21-40 are rejected below.
Claim Objections
Claim 21 is objected to because of the following informalities: change “grove” to “groove”. Appropriate correction is required.
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 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 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.
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.
Claims 21-23, 26-28, 31, 34-37, 39, and 40 are rejected under 35 U.S.C. 103 as being unpatentable over Subramaniyan (US 2018/0328212) in view of Gentry et al. (US 2018/0231023), referred to hereafter as Gentry, and Mazzawy (WO95/34745).
With regard to claim 21:
Subramaniyan discloses a compressor for an aircraft engine (the rotor and shroud of Subramaniyan are capable of being used in a compressor), comprising: a rotor having a plurality of blades (28) mounted for rotation about a central axis (Fig. 2), the plurality of blades having blade tips extending between leading and trailing edges (see tip 50 and leading and trailing edges 52 and 54 in Fig. 2, 3, 12-29); and a shroud (29) surrounding the rotor and having an inner surface surrounding the blade tips (Fig. 2, 12-29), a plurality of grooves (31, Fig. 12-29) defined in said inner surface of the shroud adjacent said blade tips (Fig. 12-29), the plurality of grooves being annular and extending circumferentially about the shroud (Fig. 12, abstract), each of the plurality of grooves extending radially outward from groove inlet openings defined in the inner surface to closed end surfaces of the plurality of grooves (Fig. 12-29), the plurality of grooves being axially spaced-apart from each other (Fig. 12-29), the plurality of grooves spanning an overall axial distance corresponding to 30% or more of a chord length of the plurality of blades (at least in Fig. 12-19, 25, 26, 29), wherein each of the plurality of grooves is inclined in a fore-aft direction relative to the central axis to define a swept angle from the inner surface such that a center of the groove inlet openings is axially offset of a center of a closed-end surface of each of the plurality of grooves (Fig. 17, 18).
Subramaniyan does not appear to explicitly disclose that the groove inlet opening of the most upstream one of the plurality of circumferential grooves having an upstream end disposed upstream of the leading edges of the plurality of blades and a downstream end disposed downstream of the leading edges of the plurality of blades. Subramaniyan also does not appear to explicitly disclose that the plurality of grooves have circumferential interruptions defined by a plurality of baffles within the plurality of grooves such that each of the plurality of grooves extends circumferentially non-continuously around a shroud circumference. Subramaniyan also does not appear to explicitly disclose that the plurality of baffles within the plurality of grooves are circumferentially angled in a circumferential direction relative to an axis normal to the inner surface of the shroud, such that a center of the plurality of baffles at the grove inlet openings is circumferentially offset form the center of the plurality of baffles at the closed-end surface of the plurality of grooves.
With regard to the position of the groove inlet opening of the most upstream groove, Gentry, which is in the same field of endeavor of casing treatments, teaches a compressor with a casing treatment that comprises grooves (see grooves in grooved sections 304 and 304’ in 300 and 300’ in Fig. 3A, 3B, and when they are applied to the shroud casing treatments 400, 420, 440, and 460 as grooved sections 408, 428, 448, and 458 in Fig. 4-7) and further teaches that the groove inlet opening of the most upstream groove has an upstream end disposed upstream of the leading edges of the plurality of blades (see Fig. 5 and 7 along with their descriptions in [0030] and [0032], which in their last two sentences specifically teach that the grooved section is positioned with a beginning that is upstream of the leading edge of the blade). Gentry teaches that the grooved section may extend to a position upstream of the leading edge ([0018]), and that the purpose of the grooves is for resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition ([0006], [0007]). Gentry further teaches that the specific location of the grooves may be modified for resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions ([0033]). Therefore, Gentry establishes a result effective variable optimization in which the variable, namely “the specific location of the grooves”, affects the resulting reverse axial fluid flow, with the optimization goal of resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the compressor of Subramaniyan with different groove locations through routine experimentation and choose a groove location that best suits their particular application at hand and arrive at a groove location where the groove inlet opening of the most upstream one of the plurality of circumferential grooves has an upstream end disposed upstream of the leading edges of the plurality of blades (as explicitly shown in Gentry), and a downstream end disposed downstream of the leading edges of the plurality of blades, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05. Furthermore, this combination would provide the benefit of resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition.
With regard to the baffles, Mazzawy, which is in the same field of endeavor of casing treatments, teaches a casing treatment comprising a plurality of grooves (38, Fig. 2-5) and further teaches that the plurality of grooves have circumferential interruptions defined by a plurality of baffles within the plurality of grooves (42, Fig. 2-5) such that each of the plurality of grooves extends circumferentially non-continuously around a shroud circumference (Fig. 2-5). Mazzawy further teaches that the baffles increase the surge margin with little or no decrease in the aerodynamic efficiency (page 8; lines 29-30, also see Fig. 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to add circumferential interruptions defined by a plurality of baffles within the plurality of grooves such that each of the plurality of grooves extends circumferentially non-continuously around a shroud circumference, in order to increase the surge margin with little or no decrease in the aerodynamic efficiency.
With regard to the baffles being angled, a careful examination of the specification reveals that no criticality for the “baffles being circumferentially angled such that a center of the plurality of baffles at the grove inlet openings is circumferentially offset form the center of the plurality of baffles at the closed-end surface of the plurality of grooves” has been shown, nor any reason as to why the compressor of the applicant with the recited angled baffles would operate any different than the compressor of the combination of Subramaniyan and Gentry and Mazzawy, and Applicant has not disclosed that these specific baffle angles provide an advantage, are used for a particular purpose, or solve a stated problem. On the contrary, according to the specification, the baffle angle values are merely one of the possible disclosed alternatives. The specification discloses that “In some embodiments, the angle ϕ may vary from -75° to +75°, i.e. into or away from a rotational direction of the blades 15” ([0032]). The specification further discloses that “The shape of the baffles 30 may vary”, and note that a baffle angle is part of its shape ([0032]). There is no mention of any criticality or advantage or purpose behind the recited baffle angles in the specification, especially for them being non-zero, because a zero angle (i.e., no angle) is included in the range of -75° to +75° given by the specification. Hence the recited circumferential angle and orientation of baffles is considered to be a design choice by the applicant. One of ordinary skill in the art, furthermore, would have expected the combination of Subramaniyan and Gentry and Mazzawy, and Applicant’s invention, to perform equally well, because both would perform the same function of a casing treatment, which is increasing the aerodynamically stable operating range of the compressor.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to combine the circumferentially angled baffles as claimed with the compressor of the combination of Subramaniyan and Gentry and Mazzawy in order to achieve a desired dimension, orientation, or configuration, as they are a matter of design choice. Such a modification would have been considered a mere design consideration which fails to patentably distinguish over the prior art.
With regard to claim 35:
Subramaniyan discloses a compressor for an aircraft engine (the rotor and shroud of Subramaniyan are capable of being used in a compressor), comprising: a rotor having a plurality of blades (28) mounted for rotation about a central axis (Fig. 2), the plurality of blades having blade tips extending between leading and trailing edges (see tip 50 and leading and trailing edges 52 and 54 in Fig. 2, 3, 12-29); and a shroud (29) surrounding the rotor and having an inner surface surrounding the blade tips (Fig. 2, 12-29), a plurality of grooves (31, Fig. 12-29) defined in said inner surface of the shroud adjacent said blade tips (Fig. 12-29), the plurality of grooves extending circumferentially about the shroud (Fig. 12, abstract) and extending radially from groove inlet openings defined in the inner surface to closed end surfaces of the plurality of grooves (Fig. 12-29), the plurality of grooves having sidewalls extending circumferentially about the central axis (Fig. 12-29), the plurality of grooves being axially spaced-apart from each other (Fig. 12-29), the plurality of grooves inclined in a fore-aft direction relative to the central axis to define a swept angle from the inner surface such that a center of the groove inlet openings is axially offset of a center of a closed-end surface of each of the plurality of grooves (Fig. 17, 18).
Subramaniyan does not appear to explicitly disclose that the leading edge of the plurality of blades axially disposed between an upstream end of the groove inlet opening of the most upstream one of the plurality of grooves and a downstream end of the groove inlet opening of the most upstream one of the plurality of grooves. Subramaniyan also does not appear to explicitly disclose that the plurality of grooves have circumferential interruptions defined by a plurality of baffles such that each of the plurality of grooves extends circumferentially non-continuously around a shroud circumference. Subramaniyan also does not appear to explicitly disclose that the plurality of grooves are angled in a circumferential direction relative to an axis normal to the inner surface such that the center of each of the groove inlet openings is circumferentially offset of the center of the closed-end surface of each of the plurality of grooves.
With regard to the position of the leading edge, Gentry, which is in the same field of endeavor of casing treatments, teaches a compressor with a casing treatment that comprises grooves (see grooves in grooved sections 304 and 304’ in 300 and 300’ in Fig. 3A, 3B, and when they are applied to the shroud casing treatments 400, 420, 440, and 460 as grooved sections 408, 428, 448, and 458 in Fig. 4-7) and further teaches that the groove inlet opening of the most upstream groove has an upstream end disposed upstream of the leading edges of the plurality of blades (see Fig. 5 and 7 along with their descriptions in [0030] and [0032], which in their last two sentences specifically teach that the grooved section is positioned with a beginning that is upstream of the leading edge of the blade). Gentry teaches that the grooved section may extend to a position upstream of the leading edge ([0018]), and that the purpose of the grooves is for resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition ([0006], [0007]). Gentry further teaches that the specific location of the grooves may be modified for resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions ([0033]). Therefore, Gentry establishes a result effective variable optimization in which the variable, namely “the specific location of the grooves”, affects the resulting reverse axial fluid flow, with the optimization goal of resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the compressor of Subramaniyan with different groove locations through routine experimentation and choose a groove location that best suits their particular application at hand and arrive at a groove location where the groove inlet opening of the most upstream one of the plurality of circumferential grooves has an upstream end disposed upstream of the leading edges of the plurality of blades (as explicitly shown in Gentry), and a downstream end disposed downstream of the leading edges of the plurality of blades, or in other words, the leading edge of the plurality of blades axially disposed between an upstream end of the groove inlet opening of the most upstream one of the plurality of grooves and a downstream end of the groove inlet opening of the most upstream one of the plurality of grooves, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05. Furthermore, this combination would provide the benefit of resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition.
With regard to the baffles, Mazzawy, which is in the same field of endeavor of casing treatments, teaches a casing treatment comprising a plurality of grooves (38, Fig. 2-5) and further teaches that the plurality of grooves have circumferential interruptions defined by a plurality of baffles within the plurality of grooves (42, Fig. 2-5) such that each of the plurality of grooves extends non-continuously around a shroud circumference (Fig. 2-5). Mazzawy further teaches that the baffles increase the surge margin with little or no decrease in the aerodynamic efficiency (page 8; lines 29-30, also see Fig. 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to add circumferential interruptions defined by a plurality of baffles within the plurality of grooves such that each of the plurality of grooves extends non-continuously around a shroud circumference, in order to increase the surge margin with little or no decrease in the aerodynamic efficiency.
With regard to the grooves being angled, a careful examination of the specification reveals that no criticality for the “plurality of grooves angled in a circumferential direction relative to an axis normal to the inner surface such that the center of each of the groove inlet openings is circumferentially offset of the center of the closed-end surface of each of the plurality of grooves” has been shown, nor any reason as to why the compressor of the applicant with the recited angled grooves would operate any different than the compressor of the combination of Subramaniyan and Gentry and Mazzawy, and Applicant has not disclosed that these specific groove angles provide an advantage, are used for a particular purpose, or solve a stated problem. On the contrary, according to the specification, the groove angle values are merely one of the possible disclosed alternatives. The specification discloses that “In some embodiments, the angle ϕ may vary from -75° to +75°, i.e. into or away from a rotational direction of the blades 15” ([0032]). The specification further discloses that “The shape of the baffles 30 may vary”, and note that a baffle or groove angle is part of its shape ([0032]). There is no mention of any criticality or advantage or purpose behind the recited groove angles in the specification. Hence the recited circumferential angle and orientation of baffles is considered to be a design choice by the applicant. One of ordinary skill in the art, furthermore, would have expected the combination of Subramaniyan and Gentry and Mazzawy, and Applicant’s invention, to perform equally well, because both would perform the same function of a casing treatment, which is increasing the aerodynamically stable operating range of the compressor.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to combine the circumferentially angled grooves as claimed with the compressor of the combination of Subramaniyan and Gentry and Mazzawy in order to achieve a desired dimension, orientation, or configuration, as they are a matter of design choice. Such a modification would have been considered a mere design consideration which fails to patentably distinguish over the prior art.
With regard to claim 40:
Subramaniyan discloses a shroud treatment embedded in an inner surface of a compressor shroud surrounding a plurality of rotor blades (28) of an aircraft engine having a central axis (Fig. 2) about which the plurality of rotor blades rotate, comprising: a plurality of grooves (31, Fig. 12-29) defined in the inner surface of the compressor shroud adjacent blade tips of the plurality of rotor blades (see tip 50 and leading and trailing edges 52 and 54 in Fig. 2, 3, 12-29), the plurality of grooves extending circumferentially (Fig. 12, abstract) about the shroud and extending radially from groove inlet openings defined in the inner surface to closed end surfaces of the plurality of grooves (Fig. 12-29), the plurality of grooves having sidewalls extending circumferentially about the central axis (Fig. 12-29), the plurality of grooves being axially spaced-apart from each other (Fig. 12-29), the plurality of grooves spanning an overall axial distance corresponding to 30% or more of a chord length of the plurality of rotor blades (at least in Fig. 12-19, 25, 26, 29), wherein each of the plurality of grooves is inclined in a fore-aft direction relative to the central axis to define a swept angle from the inner surface such that a center of the groove inlet openings is axially offset of a center of a closed-end surface of each of the plurality of grooves (Fig. 17, 18).
Subramaniyan does not appear to explicitly disclose that the groove inlet opening of the most upstream one of the plurality of circumferential grooves having an upstream end disposed upstream of the leading edges of the plurality of blades and a downstream end disposed downstream of the leading edges of the plurality of blades. Subramaniyan also does not appear to explicitly disclose that the plurality of grooves have circumferential interruptions defined by a plurality of baffles such that each of the plurality of grooves extends non-continuously around a circumference of the compressor shroud. Subramaniyan also does not appear to explicitly disclose that each of the plurality of grooves is angled in a circumferential direction relative to a plane normal to the inner surface of the compressor shroud such that the upstream end of each of the plurality of groove inlet openings is circumferentially offset of the downstream end of each of the plurality of groove inlet openings relative to the central axis.
With regard to the position of the groove inlet opening of the most upstream groove, Gentry, which is in the same field of endeavor of casing treatments, teaches a compressor with a casing treatment that comprises grooves (see grooves in grooved sections 304 and 304’ in 300 and 300’ in Fig. 3A, 3B, and when they are applied to the shroud casing treatments 400, 420, 440, and 460 as grooved sections 408, 428, 448, and 458 in Fig. 4-7) and further teaches that the groove inlet opening of the most upstream groove has an upstream end disposed upstream of the leading edges of the plurality of blades (see Fig. 5 and 7 along with their descriptions in [0030] and [0032], which in their last two sentences specifically teach that the grooved section is positioned with a beginning that is upstream of the leading edge of the blade). Gentry teaches that the grooved section may extend to a position upstream of the leading edge ([0018]), and that the purpose of the grooves is for resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition ([0006], [0007]). Gentry further teaches that the specific location of the grooves may be modified for resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions ([0033]). Therefore, Gentry establishes a result effective variable optimization in which the variable, namely “the specific location of the grooves”, affects the resulting reverse axial fluid flow, with the optimization goal of resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the compressor of Subramaniyan with different groove locations through routine experimentation and choose a groove location that best suits their particular application at hand and arrive at a groove location where the groove inlet opening of the most upstream one of the plurality of circumferential grooves has an upstream end disposed upstream of the leading edges of the plurality of blades (as explicitly shown in Gentry), and a downstream end disposed downstream of the leading edges of the plurality of blades, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05. Furthermore, this combination would provide the benefit of resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition.
With regard to the baffles, Mazzawy, which is in the same field of endeavor of casing treatments, teaches a casing treatment comprising a plurality of grooves (38, Fig. 2-5) and further teaches that the plurality of grooves have circumferential interruptions defined by a plurality of baffles within the plurality of grooves (42, Fig. 2-5) such that each of the plurality of grooves extends non-continuously around a shroud circumference (Fig. 2-5). Mazzawy further teaches that the baffles increase the surge margin with little or no decrease in the aerodynamic efficiency (page 8; lines 29-30, also see Fig. 6).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to add circumferential interruptions defined by a plurality of baffles within the plurality of grooves such that each of the plurality of grooves extends non-continuously around a shroud circumference, in order to increase the surge margin with little or no decrease in the aerodynamic efficiency.
With regard to the grooves being angled, a careful examination of the specification reveals that no criticality for “each of the plurality of grooves is angled in a circumferential direction relative to a plane normal to the inner surface of the compressor shroud such that the upstream end of each of the plurality of groove inlet openings is circumferentially offset of the downstream end of each of the plurality of groove inlet openings relative to the central axis” has been shown, nor any reason as to why the compressor of the applicant with the recited angled grooves would operate any different than the compressor of the combination of Subramaniyan and Gentry and Mazzawy, and Applicant has not disclosed that these specific groove angles provide an advantage, are used for a particular purpose, or solve a stated problem. On the contrary, according to the specification, the groove angle values are merely one of the possible disclosed alternatives. The specification discloses that “In some embodiments, the angle ϕ may vary from -75° to +75°, i.e. into or away from a rotational direction of the blades 15” ([0032]). The specification further discloses that “The shape of the baffles 30 may vary”, and note that a baffle or groove angle is part of its shape ([0032]). There is no mention of any criticality or advantage or purpose behind the recited groove angles in the specification. Hence the recited circumferential angle and orientation of baffles is considered to be a design choice by the applicant. One of ordinary skill in the art, furthermore, would have expected the combination of Subramaniyan and Gentry and Mazzawy, and Applicant’s invention, to perform equally well, because both would perform the same function of a casing treatment, which is increasing the aerodynamically stable operating range of the compressor.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to combine the circumferentially angled grooves as claimed with the compressor of the combination of Subramaniyan and Gentry and Mazzawy in order to achieve a desired dimension, orientation, or configuration, as they are a matter of design choice. Such a modification would have been considered a mere design consideration which fails to patentably distinguish over the prior art.
With regard to claims 22 and 37:
The combination of Subramaniyan and Gentry and Mazzawy discloses the compressor of claims 21 and 35, as set forth above, and further discloses that the upstream end of the groove inlet opening of the most upstream one of the plurality of circumferential grooves is axially spaced from the leading edge of the plurality of blades by a distance.
The combination of Subramaniyan and Gentry and Mazzawy does not appear to explicitly disclose that the distance corresponds to at most 10% of the chord length of the plurality of blades.
However, Gentry, teaches that the specific location of the grooves may be modified for resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions ([0033]). Therefore, Gentry establishes a result effective variable optimization in which the variable, namely “the specific location of the grooves”, affects the resulting reverse axial fluid flow, with the optimization goal of resisting a reverse axial fluid flow therethrough when the turbomachine or compressor section is operated at near stall conditions.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the compressor of the combination of Subramaniyan and Gentry and Mazzawy with different distances through routine experimentation and choose a distance that best suits their particular application and arrive at a distance that corresponds to at most 10% of the chord length of the plurality of blades, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05. Furthermore, this combination would provide the benefit of resisting a reverse axial fluid flow through the tip gap when the turbomachine is operated at a near stall condition.
With regard to claim 23, the combination of Subramaniyan and Gentry and Mazzawy further discloses that the plurality of baffles are circumferentially spaced apart and project from the closed end surfaces to the groove inlet openings (Mazzawy, Fig. 2-5).
With regard to claim 26, the combination of Subramaniyan and Gentry and Mazzawy further discloses that the plurality of circumferential grooves have a forwardly swept angle from the inner surface such that the center of the groove inlet openings is located axially rearward of the center of the closed-end surface of each of the plurality of circumferential grooves (Subramaniyan, Fig. 17, 18).
With regard to claim 27, the combination of Subramaniyan and Gentry and Mazzawy further discloses that each of the plurality of grooves includes a forward or rearward groove swept angle of more than 0 degrees and less than 75 degrees (Fig. 17, 18. Also see [0070] disclosing “inclined forward” and “inclined aftward”, which encompasses all inclinations including the rather broad range of 0 to 75).
With regard to claim 28:
the combination of Subramaniyan and Gentry and Mazzawy discloses the compressor of claim 21, as set forth above.
compressor does not appear to explicitly disclose that each of the plurality of grooves is angled in the circumferential direction in a clockwise or counterclockwise direction at an angle of up to 75 degrees relative to the axis normal to the inner surface of the shroud.
However, a careful examination of the specification reveals that no criticality for “each of the plurality of grooves being angled in the circumferential direction in a clockwise or counterclockwise direction at an angle of up to 75 degrees relative to the axis normal to the inner surface of the shroud” has been shown, nor any reason as to why the compressor of the applicant with the recited angled grooves would operate any different than the compressor of the combination of Subramaniyan and Gentry and Mazzawy, and Applicant has not disclosed that these specific groove angles provide an advantage, are used for a particular purpose, or solve a stated problem. On the contrary, according to the specification, the groove angle values are merely one of the possible disclosed alternatives. The specification discloses that “In some embodiments, the angle ϕ may vary from -75° to +75°, i.e. into or away from a rotational direction of the blades 15” ([0032]). The specification further discloses that “The shape of the baffles 30 may vary”, and note that a baffle angle is part of its shape ([0032]). There is no mention of any criticality or advantage or purpose behind the recited groove or baffle angles in the specification, especially for them being non-zero, because a zero angle (i.e., no angle) is included in the range of -75° to +75° given by the specification. Hence the recited circumferential angle and orientation of the grooves is considered to be a design choice by the applicant. One of ordinary skill in the art, furthermore, would have expected the combination of Subramaniyan and Gentry and Mazzawy, and Applicant’s invention, to perform equally well, because both would perform the same function of a casing treatment, which is increasing the aerodynamically stable operating range of the compressor.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to combine the circumferentially angled grooves as claimed with the compressor of the combination of Subramaniyan and Gentry and Mazzawy in order to achieve a desired dimension, orientation, or configuration, as they are a matter of design choice. Such a modification would have been considered a mere design consideration which fails to patentably distinguish over the prior art.
With regard to claim 31, the combination of Subramaniyan and Gentry and Mazzawy further discloses that the closed end surfaces of the plurality of grooves are rounded closed end surfaces (Subramaniyan, Fig. 16-18).
With regard to claim 34, the combination of Subramaniyan and Gentry and Mazzawy further discloses that depths of the plurality of grooves are constant from the most upstream one of the plurality of circumferential grooves to the most downstream one of the plurality of circumferential grooves (Subramaniyan, Fig. 13-29).
With regard to claim 36, the combination of Subramaniyan and Gentry and Mazzawy further discloses that the plurality of grooves span an overall axial distance corresponding to 30% or more of a chord length of the plurality of blades (Subramaniyan, at least in Fig. 12-19, 25, 26, 29).
With regard to claim 39, the combination of Subramaniyan and Gentry and Mazzawy further discloses that depths of the plurality of grooves are constant from the most upstream one of the plurality of grooves to the most downstream one of the plurality of grooves (Subramaniyan, Fig. 13-29).
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Claims 24, 25, 29, 30, 33, and 38 are rejected under 35 U.S.C. 103 as being unpatentable over Subramaniyan (US 2018/0328212) in view of Gentry et al. (US 2018/0231023), referred to hereafter as Gentry, and Mazzawy (WO95/34745), as applied to claims 21 and 35 above, and further in view of Montgomery (US 2011/0299979).
With regard to claims 24, 25, and 38:
The combination of Subramaniyan and Gentry and Mazzawy discloses the compressor of claims 21 and 35, as set forth above, and further discloses that a first axial gap of the plurality of axial gaps is defined between a first pair of adjacent plurality of circumferential grooves and a second axial gap of the plurality of axial gaps is defined between a second pair of adjacent plurality of circumferential grooves.
The combination of Subramaniyan and Gentry and Mazzawy does not appear to explicitly disclose that the first axial gap having a distance different than a distance of the second axial gap, wherein a ratio of each axial gap distance between pairs of adjacent plurality of circumferential grooves and a width of each of the plurality of circumferential grooves ranges between 0.5 and 5.
However, Montgomery, which is in the same field of endeavor of casing treatments, teaches casing treatments comprising a plurality of grooves with axial gaps with the first axial gap having a distance different than a distance of the second axial gap (Fig. 12), and a ratio of each axial gap distance between pairs of adjacent plurality of grooves and a width of each of the plurality of grooves ranges between 0.5 and 5 (Fig. 12). Montgomery further teaches that the axial gap between adjacent grooves and the width of the grooves are amongst the groove parameters which include, but are not limited to: the number of grooves; the groove depth of a groove; the groove width of a groove; the axial spacing (gap) between adjacent grooves; the distance from the blade tip leading edge to the first groove; the distance from the blade tip trailing edge to the last groove; the groove cross section; and combinations thereof, and teaches that the analyst has the freedom to combine as many or as few of the groove parameters as desired to achieve the desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance. Therefore, Montgomery establishes a result effective variable optimization in which the variables, namely groove parameters including the gap and width of the grooves, affect the results of a desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance ([0050]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the plurality of circumferential grooves of the combination of Subramaniyan and Gentry and Mazzawy with different groove parameters such as the axial gap between adjacent grooves and the width of the grooves, through routine experimentation, to achieve the desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance, and choose axial gaps and widths that best suits their particular application, and arrive at the claimed limitation that the first axial gap having a distance different than a distance of the second axial gap, wherein a ratio of each axial gap distance between pairs of adjacent plurality of circumferential grooves and a width of each of the plurality of circumferential grooves ranges between 0.5 and 5, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05.
With regard to claim 29:
The combination of Subramaniyan and Gentry and Mazzawy discloses the compressor of claim 21, as set forth above, and further discloses that the plurality of grooves each have a radius.
The combination of Subramaniyan and Gentry and Mazzawy does not appear to explicitly disclose that the radius increases or decreases in magnitude from an upstream end of the shroud to a downstream end of the shroud.
However, Montgomery, which is in the same field of endeavor of casing treatments, teaches casing treatments comprising a plurality of grooves with a radius and further teaches that the radius of the grooves are amongst the groove parameters which include, but are not limited to: the number of grooves; the groove depth of a groove (i.e., groove radius); the groove width of a groove; the axial spacing (gap) between adjacent grooves; the distance from the blade tip leading edge to the first groove; the distance from the blade tip trailing edge to the last groove; the groove cross section; and combinations thereof, and teaches that the analyst has the freedom to combine as many or as few of the groove parameters as desired to achieve the desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance ([0050]). Therefore, Montgomery establishes a result effective variable optimization in which the variables, namely groove parameters including the radius of the grooves, affect the results of a desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance ([0050]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the plurality of circumferential grooves of the combination of Subramaniyan and Gentry and Mazzawy with different groove parameters such as the radius of the grooves, through routine experimentation, to achieve the desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance, and choose groove radiuses that best suits their particular application, and arrive at the claimed limitation that the plurality of grooves each have a radius that increases or decreases in magnitude from an upstream end of the shroud to a downstream end of the shroud, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05
With regard to claim 30:
The combination of Subramaniyan and Gentry and Mazzawy and Montgomery discloses the compressor of claim 21, as set forth above, and further discloses that the radius of each of the plurality of grooves increases or decreases at a taper angle from the upstream end of the shroud to the downstream end of the shroud.
The combination of Subramaniyan and Gentry and Mazzawy and Montgomery does not appear to explicitly disclose that the taper angle is 20 degrees.
However, a careful examination of the specification reveals that no criticality for the taper angle being 20 degrees has been shown, nor any reason as to why the compressor of the applicant with the recited taper angle would operate any different than the compressor of the combination of Subramaniyan and Gentry and Mazzawy and Montgomery, and Applicant has not disclosed that these specific taper angle provides an advantage, is used for a particular purpose, or solves a stated problem. On the contrary, according to the specification (see [0036]), “the taper angle of the grooves 24, i.e. the variation in radius from one groove 24 to the next, can either remain constant (ex: FIG. 7A), decrease (Ex: FIG. 7B) or increase (EX: FIG. 7C) from an upstream end to a downstream end of the casing 20. In FIG. 7A, the taper angle is shown to remain constant, i.e. a taper angle of 0° between grooves 24. In FIG. 7B, an exemplary inward or decreasing taper angle of 10°, is shown. In FIG. 7C, an exemplary outward or increasing taper angle of 10° is shown. Other inward or outward taper angles may be contemplated. For instance, in various cases the taper angle may vary from 20° inward to 20° outward.” There is no mention of any criticality or advantage or purpose behind the recited taper angle of 20 degrees in the specification. Hence the recited taper angle of 20 degrees is considered to be a design choice by the applicant. One of ordinary skill in the art, furthermore, would have expected the combination of Subramaniyan and Gentry and Mazzawy and Montgomery, and Applicant’s invention, to perform equally well, because both would perform the same function of a casing treatment, which is increasing the aerodynamically stable operating range of the compressor.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to combine the taper angle of 20 degrees as claimed with the compressor of the combination of Subramaniyan and Gentry and Mazzawy and Montgomery, in order to achieve a desired dimension, orientation, or configuration, as they are a matter of design choice. Such a modification would have been considered a mere design consideration which fails to patentably distinguish over the prior art.
With regard to claim 33:
The combination of Subramaniyan and Gentry and Mazzawy discloses the compressor of claim 21, as set forth above, and further discloses that the grooves have a width.
The combination of Subramaniyan and Gentry and Mazzawy does not appear to explicitly disclose that the width is between about 1% to about 15% of the chord length of the blades.
However, Montgomery, which is in the same field of endeavor of casing treatments, teaches casing treatments comprising a plurality of grooves with a width that is between about 1% to about 15% of the chord length of the blades ([0044]). Montgomery further teaches that the width of the grooves are amongst the groove parameters which include, but are not limited to: the number of grooves; the groove depth of a groove; the groove width of a groove; the axial spacing (gap) between adjacent grooves; the distance from the blade tip leading edge to the first groove; the distance from the blade tip trailing edge to the last groove; the groove cross section; and combinations thereof, and teaches that the analyst has the freedom to combine as many or as few of the groove parameters as desired to achieve the desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance. Therefore, Montgomery establishes a result effective variable optimization in which the variables, namely groove parameters including the width of the grooves, affect the results of a desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance ([0050]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to try the plurality of circumferential grooves of the combination of Subramaniyan and Gentry and Mazzawy with different groove parameters such as the width of the grooves, through routine experimentation, to achieve the desired increase in stall margin while trying to minimize the negative impact to aerodynamic blade performance, and choose widths that best suits their particular application, and arrive at the claimed limitation that the width is between about 1% to about 15% of the chord length of the blades, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art. MPEP 2144.05
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Claim 32 is rejected under 35 U.S.C. 103 as being unpatentable over Subramaniyan (US 2018/0328212) in view of Gentry et al. (US 2018/0231023), referred to hereafter as Gentry, and Mazzawy (WO95/34745), as applied to claim 21 above, and further in view of Collins (US 2007/0147989), and Reynolds et al. (US 2020/0208532), referred to hereafter as Reynolds.
With regard to claim 32:
The combination of Subramaniyan and Gentry and Mazzawy discloses the limitations of claim 21, as set forth above.
The combination of Subramaniyan and Gentry and Mazzawy does not appear to explicitly disclose that the compressor includes a layer of non-abradable material lined on the inner surface of the shroud about the blade tips, the layer of non-abradable material embedding the plurality of circumferential grooves and baffles.
With regard to a compressor with a layer, Collins, which is in the same field of endeavor of casing treatments, teaches a compressor having a casing treatment comprising a plurality of grooves, and further teaches that the compressor includes a layer lined on the inner surface of the shroud about the blade tips, the layer embedding the plurality of grooves, and further teaches that the purpose of the layer is for ease of construction and the possibility of repair by replacement, where the grooves are cut into a demountable layer (16) secured in a cut-out formed in the inner surface of the shroud. Collins further teaches that the layer may be made from different material compared to the remainder of the shroud ([0015]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application to have the casing treatment of combination of Subramaniyan and Gentry and Mazzawy in a compressor in a layer lined on the inner surface of the shroud about the blade tips, the layer embedding the plurality of circumferential grooves, for the purpose of ease of construction and the possibility of repair by replacement, where the grooves are cut into a demountable layer (16) secured in a cut-out formed in the inner surface of the shroud.
With regard to the material of the layer, Reynolds, which is in the same field of endeavor of casing treatments, teaches a compressor having a casing treatment comprising a plurality of grooves, and further teaches that the compressor includes a non-abradable section embedding the plurality of grooves, in order that the casing treatment may be robust and effective at resisting the reverse axial fluid flow ([0024]), and for protection from chipping away or wearing away, resulting a very robust compressor ([0053], [0057]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the application choose the material of the layer of Collins to be non-abradable, in order to have a casing treatment that is robust and effective at resisting the reverse axial fluid flow, and for protection from chipping away or wearing away, resulting a very robust compressor. Collins discloses a layer and discloses that it has a different material than the rest of the shroud, but is silent about the type of material. A person of ordinary skill in the art, needing a material type for the layer of Collins, uses the teachings of Reynolds, which is in the same field of endeavor of casing treatments, to have a material type.
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.
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/BEHNOUSH HAGHIGHIAN/
Examiner
Art Unit 3745
/COURTNEY D HEINLE/Supervisory Patent Examiner, Art Unit 3745