Method for Evaluating the Condition of a Compressor Impeller

Abstract

To provide a remaining lifetime evaluation method for a compressor impeller capable of accurately evaluating a state related to a remaining lifetime of the compressor impeller.SOLUTION: A state evaluation method for a compressor impeller for evaluating a state related to a remaining lifetime of the compressor impeller of a compressor includes: a reference shape formation step of forming a reference shape serving as an index for evaluating the state related to the remaining lifetime of the compressor impeller on a coat formed on the surface of the compressor impeller; a replica collection step of collecting a replica into which the reference shape of the coat is transcribed during inspection of the compressor; and a state evaluation step of evaluating the state related to the remaining lifetime of the compressor impeller on the basis of a change of the reference shape determined from the reference shape when the reference shape is formed in the reference shape formation step and the replica collected in the replica collection step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for evaluating the state of a compressor impeller.

Background Art

[0002] Conventionally, for example, the remaining life of a compressor impeller of a supercharger has not been accurately grasped, and the compressor impeller has been replaced based on a preset replacement period as a guideline. For this reason, when the replacement period has elapsed or when problems such as damage or creep occur in the compressor impeller, there is a possibility that the compressor impeller may be replaced even though there is a margin in the life of the compressor impeller.

[0003] Patent Document 1 discloses a life determination device for a turbo supercharger that includes a creep monitoring algorithm for monitoring the creep of a compressor wheel. This creep monitoring algorithm monitors creep by monitoring the amount of time of operation under different combinations of the detected compressor inlet temperature and the calculated pressure ratio of the compressor. The above combinations include a creep score representing the stress on the compressor wheel generated by a specific combination, and the product of the amount of time under a specific combination and the creep score becomes the creep stress damage generated in the specific combination, and the total creep stress damage is the creep to be monitored.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method described in Patent Document 1, the remaining creep life of the compressor impeller is evaluated by monitoring the amount of time the compressor operates under a combination of the inlet temperature and the pressure ratio of the compressor, and the remaining life is not evaluated based on information obtained from the compressor impeller itself. Therefore, the accuracy of the state evaluation regarding the remaining life of the compressor impeller was not necessarily high.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a method for evaluating the remaining life of a compressor impeller that can accurately evaluate the state regarding the remaining life of the compressor impeller.

Means for Solving the Problem

[0007] To achieve the above object, a method for evaluating the state of a compressor impeller according to at least one embodiment of the present disclosure is a method for evaluating the state regarding the remaining life of a compressor impeller provided in a compressor, a reference shape forming step of forming a reference shape serving as an index for evaluating the state regarding the remaining life of the compressor impeller on a coating formed on the surface of the compressor impeller; a replica collecting step of collecting a replica on which the reference shape of the coating is transferred during inspection of the compressor; a state evaluation step of evaluating the state regarding the remaining life of the compressor impeller based on the change in the reference shape obtained from the reference shape at the time when the reference shape is formed in the reference shape forming step and the replica collected in the replica collecting step; and includes.

Advantages of the Invention

[0008] According to at least one embodiment of the present disclosure, there is provided a method for evaluating the remaining life of a compressor impeller that can accurately evaluate the state regarding the remaining life of the compressor impeller.

Brief Description of the Drawings

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the invention thereto, but are merely illustrative examples. For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of being relatively displaced with tolerances or at an angle or distance such that the same function can be obtained. For example, expressions indicating that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent a state in which there are tolerances or differences to the extent that the same function can be obtained. For example, expressions indicating shapes such as a rectangular shape or a cylindrical shape not only represent shapes such as a rectangular shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. On the other hand, the expressions "comprising", "having", "including", or "possessing" one component are not exclusive expressions that exclude the existence of other components.

[0011] FIG. 1 is a flowchart showing an outline of a method for evaluating the state of a compressor impeller according to the present disclosure. The evaluation method of the compressor impeller shown in FIG. 1 includes a reference shape forming step (S101) of forming a reference shape serving as an index for evaluating the state of the compressor impeller on a coating formed on the surface of the compressor impeller, a replica collecting step (S102) of collecting a replica on which the reference shape of the coating is transferred during inspection of the compressor, and a state evaluation step (S103) of evaluating the state regarding the remaining life of the compressor impeller based on the change in the reference shape obtained from the reference shape formed in the reference shape forming step (S101) and the replica collected in the replica collecting step (S102).

[0012] FIG. 2 is a schematic perspective view showing an example of the configuration of a compressor impeller which is the object of evaluation of the compressor impeller state evaluation method shown in FIG. 1. The illustrated compressor impeller 6 is the compressor impeller 6 of the centrifugal compressor 4 provided in the supercharger 2, and the supercharger 2 includes an unillustrated turbine wheel connected to the compressor impeller 6 via a rotating shaft 8. The compressor impeller 6 includes a hub 9 and a plurality of compressor blades 10 provided at intervals in the circumferential direction on the outer peripheral surface of the hub 9.

[0013] FIG. 3 is a cross-sectional view showing the configuration in the vicinity of the surface 10s of the compressor blade 10 in the compressor impeller 6 shown in FIG. 2. In the example shown in FIG. 3, the compressor blade 10 includes a base material 14 and an anodic oxide film 16 (hereinafter simply referred to as "oxide film 16") formed on the surface of the base material 14 by anodic oxidation treatment (alumite treatment). Hereinafter, an example in which the base material 14 is an aluminum material and the oxide film 16 is an aluminum oxide film will be described.

[0014] Here, a specific example of the compressor impeller state evaluation method shown in FIG. 1 will be described with reference to FIGS. 4 to 9.

[0015] FIG. 4 is a diagram for explaining an example of the reference shape forming step (S101) shown in FIG. 1, and is an example of an enlarged view of a range S1 on the root 11 side of the compressor blade 10 shown in FIG. 2. FIG. 5 is a partial cross-sectional view showing a part of the cross-section along the direction d1 in FIG. 4.

[0016] In the examples shown in FIGS. 4 and 5, in S101, a groove 18 (notch), which serves as a reference shape (reference line) for evaluating the state of the compressor impeller 6, is formed in the oxide film 16 formed on the surface 10s of the compressor blade 10. In S101, for example, the groove 18 is formed in the oxide film 16 before the operation of the supercharger 2 is started (when the supercharger 2 is new). In S101, the location P1 where the maximum principal stress σ1 of the compressor blade 10 occurs and the direction d1 of the maximum principal stress σ1 in the operating state of the supercharger 2 are obtained in advance by analysis such as FEM, and the groove 18 may be formed in the oxide film 16 along the direction d2 orthogonal to the direction d1 of the maximum principal stress σ1 at the location P1 where the maximum principal stress σ1 occurs. In the exemplary form shown in FIG. 4, the groove 18 is formed in the negative pressure surface 12 of the compressor blade 10 on the blade root 11 side of the compressor blade 10 (on the hub 9 side rather than at the position half of the blade height of the compressor blade 10). In this specification, the operating state of the supercharger 2 means the state in which the supercharger 2 is operating, and also means the operating state of the compressor 4, that is, the state in which the compressor 4 is operating.

[0017] In S101, the groove 18 of the compressor blade 10 may be formed by, for example, laser marking, micro-etching, or other known methods. Also, in S101, as shown in FIG. 5, it is desirable that the groove 18 is formed only in the oxide film 16 so as not to damage the base material 14, but it may be formed to a depth reaching the base material 14.

[0018] When the supercharger 2 is operated after the groove 18 is formed in S101, as shown in FIGS. 6 and 7, as the operation time of the supercharger 2 increases, the creep of the base material 14 progresses, and the position of the groove 18 and the width W of the groove 18 change. FIG. 6 shows that as the operation time of the supercharger 2 increases, the position of the groove 18 changes from the position of the dotted line to the position of the solid line so as to move away from the hub 9. FIG. 7 shows that the width W of the groove 18 increases as the operation time of the supercharger 2 increases. When the creep of the base material 14 progresses with the operation of the supercharger 2, the oxide film 16 breaks at the groove 18 as a starting point, and the slightly extended portion is oxidized and the oxide film is regenerated. Therefore, an oxide film 16a thinner than the oxide film 16 formed in S101 is formed at the bottom of the groove 18.

[0019] In S102, as shown in FIG. 8, at the time of regular inspection of the supercharger 2 (at the time of open inspection of the supercharger 2), a casing (not shown) covering the compressor impeller 6 is opened, and a replica 20 of the portion of the oxide film 16 where the groove 18 is formed (a replica 20 obtained by transferring the shape of the groove 18 in the oxide film 16) is collected using a known replica method. For example, the replica 20 may be collected every time the supercharger 2 is regularly inspected. Then, by measuring the collected replica 20, the width of the groove 18 at the time when the replica 20 is collected is measured. Hereinafter, as shown in FIG. 9, the width of the groove 18 measured from the replica 20 collected at the i-th (i is an integer of 1 or more) regular inspection of the supercharger 2 is denoted as Wi. The broken line in FIG. 9 shows the movement and shape change of the groove 18 over time.

[0020] In S103, from the width W0 of the groove 18 at the time when the groove 18 is formed in S101 (the initial value of the width W of the groove 18) and the width Wi of the groove 18 measured from the replica 20 collected at the i-th (i is an integer of 1 or more) regular inspection of the supercharger 2 in S103, the change amount (Wi - W0) of the width W of the groove 18 from the time when the groove 18 is formed to the time of the i-th regular inspection is calculated, and based on the calculated change amount of the width (Wi - W0), the state regarding the remaining life of the compressor impeller 6 is evaluated.

[0021] In this case, for example, correlation information R1 between the amount of change (Wi - W0) in the width of the groove 18 and the remaining life of the compressor impeller 6 is obtained in advance, and based on the amount of change (Wi - W0) in the width of the groove 18 and the correlation information R1, the remaining life of the compressor impeller 6 at the time of the i-th regular inspection of the supercharger 2 may be calculated. For example, when the amount of change (Wi - W0) in the width of the groove 18 exceeds a preset threshold value, the compressor impeller 6 may be replaced, and when the amount of change (Wi - W0) in the width of the groove 18 is equal to or less than the preset threshold value, it may be determined that the compressor impeller 6 is to be continuously used without replacement. Also, in S103, the remaining life of the compressor impeller 6 may be evaluated based on the amount of change (Wi - W0) in the width of the groove 18 and the progress of the oxide film 16a at the bottom of the groove 18. Thus, the "state regarding the remaining life" of the compressor impeller 6 evaluated in S103 may be, for example, the remaining life of the compressor impeller 6 itself, or a state that serves as an index for determining whether to continuously use or replace the compressor impeller 6 during the inspection of the supercharger 2, or other states regarding the remaining life of the compressor impeller 6.

[0022] Here, the effects of the above-described method for evaluating the state of the compressor impeller 6 will be described. As described above, the groove 18 formed in the oxide film 16 in S101 deforms due to the progress of creep as the operation time of the supercharger 2 elapses. Therefore, by evaluating the state regarding the remaining life of the compressor impeller 6 based on the shape of the groove 18 at the time when the groove 18 was formed in S101 and the change over time in the shape of the groove 18 obtained from the replica 20 collected in S102, it is possible to accurately evaluate the state regarding the remaining life of the compressor impeller 6 that reflects the influence received by the compressor impeller 6 during the operation of the supercharger 2. Also, it is possible to appropriately evaluate whether to continuously use the compressor impeller 6 during the inspection of the supercharger 2, and it becomes possible to optimize the limit use of the compressor impeller 6 and the replacement timing of the compressor impeller 6.

[0023] Further, in S101, by forming the groove 18 on the blade root 11 side of the compressor blade 10 where relatively large stress is likely to occur, it is possible to accurately evaluate the state regarding the remaining life due to the stress in the compressor impeller 6. In particular, by forming the groove 18 along the direction d2 orthogonal to the direction of the maximum principal stress σ1 at the location P1 where the maximum principal stress σ1 occurs in the compressor blade 10, as the operation of the supercharger 2 progresses, the width W of the groove 18 expands in the direction of the maximum principal stress σ1. Therefore, the expansion of the width W of the groove 18 becomes clear, and inverse analysis of the stress state of the compressor impeller 6 becomes possible.

[0024] Also, as the operation time of the supercharger 2 elapses, due to the progress of creep, the width W of the groove 18 on the surface of the compressor impeller 6 increases. Therefore, by evaluating the state regarding the remaining life of the compressor impeller 6 based on the change amount (Wi - W0) of the width of the groove 18, it is possible to accurately evaluate the state regarding the remaining life of the compressor impeller.

[0025] Next, with reference to FIGS. 10 to 13, another specific example of the state evaluation method of the compressor impeller shown in FIG. 1 will be described. FIG. 10 is a diagram for explaining an example of the reference shape formation step (S101) shown in FIG. 1, and is an example of an enlarged view of the range S1 in FIG. 2.

[0026] In the example shown in FIG. 10, in S101, a reference mark 30 as a reference shape serving as an index for evaluating the state of the compressor impeller 6 is formed on the oxide film 16 formed on the surface of the compressor blade 10. In S101, for example, the reference mark 30 is formed on the oxide film 16 before the operation of the supercharger 2 starts (when the supercharger 2 is new). In S101, the location P1 where the maximum principal stress σ1 of the compressor blade 10 occurs and the direction d1 of the maximum principal stress σ1 in the operating state of the supercharger 2 are obtained in advance by analysis such as FEM, and the reference mark 30 may be formed at the location P1 where the maximum principal stress σ1 occurs. In the exemplary form shown in FIG. 10, the reference mark 30 is formed on the negative pressure surface 12 of the compressor blade 10 on the hub 9 side (on the side closer to the hub 9 than half of the blade height of the compressor blade 10) of the root 11 side of the compressor blade 10. Further, the reference mark 30 may be formed by, for example, laser marking, micro-etching, or other known methods. The reference mark 30 is preferably formed only on the oxide film 16 so as not to damage the base material 14 (see FIG. 3), but may be formed to a depth reaching the base material 14.

[0027] In the example shown in FIG. 10, in S101, a reference mark 30 including a circular groove 32 formed along a circle C1 and four linear grooves 34 linearly extending from the circular groove 32 toward the outer peripheral side of the circular groove 32 is formed. The four linear grooves 34 are arranged at 90-degree intervals around the center of the circular groove 32 (the center of the circle C1). The four linear grooves 34 include two linear grooves 34a formed along a first straight line L1 (see FIG. 11) and two linear grooves 34b formed along a second straight line L2 (see FIG. 11) orthogonal to the first straight line L1. Here, the first straight line L1 may be a straight line along the direction of the maximum principal stress σ1 of the compressor blade 10 in the operating state of the supercharger 2. That is, the two linear grooves 34a may be formed along the direction of the maximum principal stress σ1 of the compressor blade 10 in the operating state of the supercharger 2.

[0028] When the supercharger 2 is operated after the reference mark 30 is formed in S101, as shown in FIG. 12, as the cumulative operation time of the supercharger 2 increases, the reference mark 30 is deformed due to the progress of creep of the base material 14 (see FIG. 3). The deformation of the reference mark 30 is not limited to the progress of creep, and can also occur when the compressor impeller 6 is damaged due to overspeed rotation of the supercharger 2. In the example shown in FIG. 12, the shape of the reference mark 30 has changed from the shape indicated by the broken line to the shape indicated by the solid line.

[0029] In S102, during the regular inspection of the supercharger 2, an unillustrated casing covering the compressor impeller 6 is opened, and a replica of the portion where the reference mark 30 is formed on the oxide film 16 (an unillustrated replica in which the shape of the reference mark 30 on the oxide film 16 is transferred) is collected using a known replica method. The collection of the above replica may be performed, for example, every time the supercharger 2 is regularly inspected.

[0030] In S103, the shape of the reference mark 30 at the time when the reference mark 30 of S101 was formed (the initial shape of the reference mark 30 when the supercharger 2 was new) is compared with the shape of the reference mark 30 at the i-th regular inspection of the supercharger 2 in S102 obtained from the above replica collected at the i-th regular inspection of the supercharger 2 in S102 (see FIG. 13), and the change in the shape of the reference mark 30 from the time when the reference mark 30 of S101 was formed to the time of the i-th regular inspection of the supercharger 2 in S102 is observed. Then, based on the change over time in the shape of the reference mark 30 from the time when the reference mark 30 of S101 was formed to the time of the i-th regular inspection of the supercharger 2 in S102, the state regarding the remaining life of the compressor impeller 6 at the time of the i-th regular inspection is evaluated.

[0031] Here, the effects of the method for evaluating the state of the compressor impeller described with reference to FIGS. 10 to 13 and the like will be described.

[0032] As described above, as the operating time of the supercharger 2 elapses, the shape of the reference mark 30 on the surface of the compressor impeller 6 changes two-dimensionally due to the progress of creep. Therefore, based on the shape of the reference mark 30 at the time when the reference mark 30 is formed in S101 and the two-dimensional change in the shape of the reference mark 30 obtained from the replica 20 collected in S102 (the two-dimensional change on the surface 10s of the compressor blade 10), the principal stress direction can be grasped and the amount of deformation of the reference mark 30 along the principal stress direction can be grasped, and the state regarding the remaining life of the compressor impeller 6 can be accurately evaluated. Further, by observing the change in the reference mark (change to an elliptical shape and change in the angle of the cross mark), the principal stress direction can be grasped, and inverse analysis of the stress state of the compressor impeller 6 becomes possible. Also, it is possible to appropriately evaluate whether to continue using the compressor impeller 6 during the regular inspection of the supercharger 2, and it becomes possible to optimize the limit use of the compressor impeller 6 and the replacement timing of the compressor impeller 6.

[0033] In particular, based on the deformation of the circular groove 32 in the reference mark 30 (in the example shown in FIG. 13, the deformation of gradually flattening from a circle) to grasp the principal stress direction, and based on the change in the inclination of the linear groove 34 to grasp the deformation (twist) in the rotational direction of the reference mark 30 around the center of the circular groove 32, the state regarding the remaining life of the compressor impeller 6 can be accurately evaluated.

[0034] Also, since the four linear grooves 34 are arranged around the circular groove 32 along two mutually orthogonal straight lines L1 and L2, the deformation of the reference mark 30 can be clearly grasped. Thereby, the state regarding the remaining life of the compressor impeller 6 can be accurately evaluated. In particular, by setting the straight line L1 as a straight line along the direction of the maximum principal stress σ1 of the compressor blade 10 in the operating state of the supercharger 2 (by forming the two linear grooves 34a along the direction of the maximum principal stress σ1), the deformation of the reference mark 30 in the direction along the principal stress can be clearly grasped. Thereby, the state regarding the remaining life of the compressor impeller 6 can be accurately evaluated.

[0035] The present disclosure is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

[0036] For example, some data that affects the remaining life of the supercharger 2, such as engine data indicating the operating state of the engine, is acquired as online data in real time, and a remaining life evaluation method for evaluating the remaining life of the impeller in real time based on the online data may be combined with the above-described compressor impeller state evaluation method of the present disclosure. In this case, the remaining life of the compressor impeller evaluated using the above-described replica at the time of regular inspection of the supercharger 2 may be used to correct the remaining life of the compressor impeller evaluated in real time based on online data after the regular inspection of the supercharger 2. Thereby, the state regarding the remaining life of the compressor impeller 6 can be evaluated with higher accuracy.

[0037] In some of the above-described embodiments, as an example of the location where the reference shape is provided in S101, the range S1 in FIG. 2 is shown. However, there may be a plurality of locations where the reference shape is provided. For example, it may be provided in the range S2 near the trailing edge of the compressor blade 10 in FIG. 2. Further, the reference shape may be provided for each of the compressor blades 10. Further, the reference shape may be formed on the pressure surface of the compressor blade 10 or may be formed on the tip side of the compressor blade 10. Note that by providing a plurality of locations where the reference shape is provided, the pre-analysis results can be verified, leading to an improvement in future analysis accuracy. Further, the overall deformation (creep form) of the compressor impeller 6 due to long-term operation can be grasped. Further, by providing the reference shape on the tip side of the compressor blade 10, the influence of the temperature gradient of the compressor impeller 6 can be verified. For example, by providing the reference shape on each of the tip side and the root side of the compressor blade 10, the influence of the temperature gradient in the blade height direction of the compressor blade 10 during operation of the compressor 4 can be verified. Further, for example, by providing a plurality of reference shapes at intervals in the air flow direction on the compressor blade 10, the influence of the temperature gradient in the air flow direction during operation of the compressor 4 can be verified.

[0038] The content described in each of the above embodiments is understood as follows, for example.

[0039] (1) The method for evaluating the state of a compressor impeller according to at least one embodiment of the present disclosure is a method for evaluating the state of a compressor impeller (for example, the compressor impeller 6 described above) provided in a compressor (for example, the compressor 4 described above) regarding the remaining life, a reference shape forming step of forming a reference shape (for example, the groove 18 or the reference mark 30 described above) serving as an index for evaluating the state regarding the remaining life of the compressor impeller on a coating (for example, the oxide coating 16 described above) formed on the surface of the compressor impeller, a replica collecting step of collecting a replica (for example, the replica 20 described above) in which the reference shape of the coating is transferred when the compressor is inspected, a state evaluation step of evaluating the state regarding the remaining life of the compressor impeller based on the change in the reference shape obtained from the reference shape at the time when the reference shape is formed in the reference shape forming step and the replica collected in the replica collecting step, and includes.

[0040] According to the method for evaluating the state of a compressor impeller described in the above (1), the reference shape formed on the coating in the reference shape forming step is deformed by the progress of creep as the operation time of the compressor elapses. Therefore, by collecting a replica in which the reference shape is transferred when the compressor is inspected and evaluating the state regarding the remaining life of the compressor impeller based on the change in the reference shape, it is possible to accurately evaluate the state regarding the remaining life of the compressor impeller that reflects the influence received by the compressor impeller during the operation of the compressor. In addition, it is possible to appropriately evaluate whether to continue using the compressor impeller when the compressor is inspected, and it becomes possible to optimize the limit use of the compressor impeller and the replacement timing of the compressor impeller.

[0041] (2) In some embodiments, in the method for evaluating the state of the compressor impeller described in (1) above, In the reference shape forming step, the reference shape is formed on the root side (for example, the side of the root 11 described above) of the compressor blade (for example, the compressor blade 10 described above).

[0042] According to the method for evaluating the state of the compressor impeller described in (2) above, by forming the reference shape on the root side of the compressor blade where relatively large stress is likely to occur, it is possible to accurately evaluate the state regarding the remaining life caused by stress in the compressor impeller.

[0043] (3) In some embodiments, in the method for evaluating the state of the compressor impeller described in (1) or (2) above, In the reference shape forming step, the reference shape is formed at the location (for example, the location P1 described above) where the maximum principal stress of the compressor blade occurs in the operating state of the compressor.

[0044] According to the method for evaluating the state of the compressor impeller described in (3) above, by forming the reference shape at the location where the maximum principal stress occurs in the compressor blade, it is possible to accurately evaluate the state regarding the remaining life caused by stress in the compressor impeller.

[0045] (4) In some embodiments, in the method for evaluating the state of the compressor impeller described in any one of (1) to (3) above, In the reference shape forming step, a groove (for example, the groove 18 described above) is formed as the reference shape in the coating, The state evaluation step evaluates the state regarding the remaining life of the compressor impeller based on the change in the width of the groove (for example, the change amount (Wi - W0) described above).

[0046] According to the method for evaluating the state of the compressor impeller described in (4) above, as the operation time of the compressor elapses, the width of the groove on the surface of the compressor impeller increases due to the progress of creep. Therefore, by evaluating the state regarding the remaining life of the compressor impeller based on the change in the width of the groove, the state regarding the remaining life of the compressor impeller can be accurately evaluated.

[0047] (5) In some embodiments, in the method for evaluating the state of the compressor impeller described in (4) above, In the reference shape formation step, the groove is formed along a direction orthogonal to the direction of the maximum principal stress of the compressor blade in the operating state of the compressor.

[0048] According to the method for evaluating the state of the compressor impeller described in (5) above, by forming a groove along a direction orthogonal to the direction of the maximum principal stress of the compressor blade in the operating state of the compressor, based on the amount of change in the width of the groove reflecting the influence of the maximum principal stress during the operation of the compressor, the state regarding the remaining life of the compressor impeller can be accurately evaluated.

[0049] (6) In some embodiments, in the method for evaluating the state of the compressor impeller described in any one of (1) to (3) above, In the reference shape formation step, a reference mark (for example, the above-mentioned reference mark 30) as the reference shape is formed on the coating film, The state evaluation step evaluates the state regarding the remaining life of the compressor impeller based on the change in the shape of the reference mark.

[0050] According to the method for evaluating the state of the compressor impeller described in (6) above, as the operation time of the compressor elapses, the shape of the reference mark on the surface of the compressor impeller changes two-dimensionally due to the progress of creep. Therefore, based on the two-dimensional change in the shape of the reference mark, the principal stress direction and the amount of deformation of the reference mark along the principal stress direction can be grasped, and the state regarding the remaining life of the compressor impeller can be accurately evaluated.

[0051] (7) In some embodiments, in the method for evaluating the state of the compressor impeller described in (6) above, In the reference shape forming step, a reference mark including a circular groove formed along a circle and at least one linear groove (for example, the four linear grooves 34 described above) linearly extending from the circular groove toward the outer peripheral side of the circular groove is formed.

[0052] According to the method for evaluating the state of the compressor impeller described in (7) above, the principal stress direction can be grasped based on the deformation of the circular groove, and the rotation (twist) of the reference mark around the center of the circular groove can be grasped based on the change in the inclination of the linear groove. Thereby, the state regarding the remaining life of the compressor impeller can be accurately evaluated.

[0053] (8) In some embodiments, in the method for evaluating the state of the compressor impeller described in (7) above, In the reference shape forming step, a reference mark including the circular groove and four linear grooves linearly extending toward the outer peripheral side of the circular groove is formed, The four linear grooves are arranged at 90-degree intervals around the center of the circular groove, The four linear grooves include two linear grooves (for example, the two linear grooves 34a described above) formed along a first straight line (for example, the first straight line L1 described above) and two linear grooves (for example, the two linear grooves 34b described above) formed along a second straight line (for example, the second straight line L2 described above) orthogonal to the first straight line.

[0054] According to the method for evaluating the state of the compressor impeller described in (8) above, since the four linear grooves are arranged around the circular groove along two straight lines orthogonal to each other, the deformation of the reference mark can be clearly grasped. Thereby, the state regarding the remaining life of the compressor impeller can be accurately evaluated.

[0055] (9) In some embodiments, in the method for evaluating the state of the compressor impeller described in (8) above, The two linear grooves formed along the first straight line are formed along the direction of the maximum principal stress of the compressor blades of the compressor impeller in the operating state of the compressor.

[0056] According to the method for evaluating the state of the compressor impeller described in (9) above, the deformation of the reference mark in the direction along the principal stress can be clearly grasped. Thereby, the state regarding the remaining life of the compressor impeller can be accurately evaluated.

Explanation of Reference Signs

[0057] 2 Supercharger 4 Centrifugal Compressor 6 Compressor Impeller 8 Rotating Shaft 9 Hub 10 Compressor Blade 11 Blade Root 12 Negative Pressure Surface 14 Base Material 16, 16a Oxide Film 18 Groove 20 Replica 30 Reference Mark 32 Circular Groove 34, 34a, 34b Linear Groove C1 Circle L1 First Straight Line L2 Second Straight Line R1 Correlation Information S1, S2 Range Wi, W0 Width d1, d2 Direction

Claims

1. A method for evaluating the condition of a compressor impeller regarding the remaining life of the compressor impeller provided in a compressor, comprising: a reference shape forming step of forming a reference shape serving as an index for evaluating the condition regarding the remaining life of the compressor impeller on a coating formed on the surface of the compressor impeller; a replica collecting step of collecting a replica obtained by transferring the reference shape of the coating during inspection of the compressor; a condition evaluation step of evaluating the condition regarding the remaining life of the compressor impeller based on the change in the reference shape obtained from the reference shape at the time when the reference shape was formed in the reference shape forming step and the replica collected in the replica collecting step; and in the reference shape forming step, a groove is formed as the reference shape in the coating; the condition evaluation step evaluates the condition regarding the remaining life of the compressor impeller based on the change in the width of the groove, and in the reference shape forming step, the groove is formed along a direction orthogonal to the direction of the maximum principal stress of the compressor blade in the operating state of the compressor. A method for evaluating the condition of a compressor impeller.

2. A method for evaluating the condition of a compressor impeller regarding the remaining life of the compressor impeller provided in a compressor, comprising: a reference shape forming step of forming a reference shape serving as an index for evaluating the condition regarding the remaining life of the compressor impeller on a coating formed on the surface of the compressor impeller; a replica collecting step of collecting a replica obtained by transferring the reference shape of the coating during inspection of the compressor; a condition evaluation step of evaluating the condition regarding the remaining life of the compressor impeller based on the change in the reference shape obtained from the reference shape at the time when the reference shape was formed in the reference shape forming step and the replica collected in the replica collecting step; and In the reference shape forming step, a reference mark as the reference shape is formed on the coating, The state evaluation step evaluates the state regarding the remaining life of the compressor impeller based on a change in the shape of the reference mark, and A method for evaluating the state of a compressor impeller, wherein in the reference shape forming step, a reference mark including a circular groove formed along a circle and at least one linear groove linearly extending from the circular groove toward the outer peripheral side of the circular groove is formed.

3. The method for evaluating the state of a compressor impeller according to claim 1 or 2, wherein in the reference shape forming step, the reference shape is formed on the root side of the compressor blade.

4. The method for evaluating the state of a compressor impeller according to claim 1 or 2, wherein in the reference shape forming step, the reference shape is formed at a location where the maximum principal stress of the compressor blade occurs in the operating state of the compressor.

5. In the reference shape forming step, a reference mark including the circular groove and four linear grooves linearly extending from the circular groove toward the outer peripheral side of the circular groove is formed, The four linear grooves are arranged at 90-degree intervals around the center of the circular groove, The method for evaluating the state of a compressor impeller according to claim 2, wherein the four linear grooves include two linear grooves formed along a first straight line and two linear grooves formed along a second straight line orthogonal to the first straight line.

6. The method for evaluating the state of a compressor impeller according to claim 5, wherein the two linear grooves formed along the first straight line are formed along the direction of the maximum principal stress of the compressor blade in the operating state of the compressor.

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