JP7696272B2 - Compressor impeller condition assessment method - Google Patents

Description

This disclosure relates to a method for evaluating the condition of a compressor impeller.

Conventionally, for example, the remaining life of a compressor impeller in a turbocharger compressor was not accurately known, and the compressor impeller was replaced based on a preset replacement period. For this reason, if the replacement period had passed or if the compressor impeller had problems such as damage or creep, it was possible that the compressor impeller would be replaced even if it still had some life left.

Patent document 1 discloses a turbocharger life determination device that includes a creep monitoring algorithm that monitors creep of the compressor wheel. The creep monitoring algorithm monitors creep by monitoring the amount of time operating under different combinations of detected compressor inlet temperatures and calculated compressor pressure ratios. The combinations include a creep score that represents the stress on the compressor wheel caused by the particular combination, and the product of the amount of time under a particular combination and the creep score is the creep stress damage caused by the particular combination, and the sum of the creep stress damage is the monitored creep.

Patent No. 4589751

The method described in Patent Document 1 evaluates the remaining creep life of the compressor impeller by monitoring the amount of time it operates under a combination of the compressor inlet temperature and pressure ratio, and does not evaluate the remaining life based on information obtained from the compressor impeller itself, so the accuracy of the evaluation of the condition of the remaining life of the compressor impeller is not necessarily high.

In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a method for assessing the remaining life of a compressor impeller that can accurately assess the condition of the compressor impeller regarding its remaining life.

In order to achieve the above object, a compressor impeller condition evaluation method according to at least one embodiment of the present disclosure includes:
A compressor impeller condition evaluation method for evaluating a condition related to a remaining life of a compressor impeller included in a compressor, comprising:
a reference shape forming step of forming a reference shape, which serves as an index for evaluating a state regarding a remaining life of the compressor impeller, on the coating formed on the surface of the compressor impeller;
a replica taking step of taking a replica having the reference shape of the coating transferred thereto during inspection of the compressor;
a condition evaluation step of evaluating a condition regarding a remaining life of the compressor impeller based on a 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 taken in the replica taking step;
Equipped with.

According to at least one embodiment of the present disclosure, a method for evaluating the remaining life of a compressor impeller is provided that can accurately evaluate the condition of the remaining life of the compressor impeller.

FIG. 1 is a flow chart showing an overview of a compressor impeller condition evaluation method according to the present disclosure. FIG. 2 is a schematic perspective view showing an example of the configuration of a compressor impeller that is an evaluation target of the compressor impeller condition evaluation method shown in FIG. 1 . 3 is a cross-sectional view showing a structure near the surface of a compressor blade 10 in the compressor impeller 6 shown in FIG. 2. 2 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 in FIG. 2. 5 is a partial cross-sectional view of the compressor blade 10, showing a portion of the cross section along direction d1 in FIG. 4. FIG. 5 is a diagram showing changes over time in the position of a groove 18 shown in FIG. 4 . 6 is a partial cross-sectional view of the compressor vane 10 showing the change over time in the position and width W of the groove 18 shown in FIG. 2 is a partial cross-sectional view of a compressor blade 10 for explaining a method of taking a replica 20. FIG. FIG. 2 is a partial cross-sectional view of a compressor blade 10 showing the width W of a groove 18 measured from a replica 20 taken at the i-th routine inspection. 2 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 in FIG. 2. 4A to 4C are diagrams for explaining the shape of a reference mark 30. 5A and 5B are diagrams showing changes in the shape of a reference mark 30 over time. 5A and 5B are diagrams showing changes in the shape of a reference mark 30 over time.

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 components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention.
For example, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
On the other hand, the expressions "comprise,""include,""have,""includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

FIG. 1 is a flow diagram showing an overview of a compressor impeller condition evaluation method according to the present disclosure.
The evaluation method for a compressor impeller shown in FIG. 1 includes a reference shape forming step (S101) of forming a reference shape serving as an index for evaluating a state of the compressor impeller on a coating formed on the surface of the compressor impeller, a replica taking step (S102) of taking a replica to which the reference shape of the coating is transferred during inspection of the compressor, and a condition evaluation step (S103) of evaluating a state regarding the remaining life of the compressor impeller based on a change in the reference shape determined from the reference shape formed in the reference shape forming step (S101) and the replica taken in the replica taking step (S102).

Figure 2 is a schematic perspective view showing an example of the configuration of a compressor impeller that is the subject of evaluation in the compressor impeller state evaluation method shown in Figure 1. The compressor impeller 6 shown is the compressor impeller 6 of a centrifugal compressor 4 equipped in a turbocharger 2, and the turbocharger 2 includes a turbine wheel (not shown) 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 spaced apart in the circumferential direction on the outer circumferential surface of the hub 9.

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

Here, we will explain a specific example of a method for evaluating the condition of the compressor impeller shown in Figure 1 using Figures 4 to 9.

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

4 and 5, in S101, a groove 18 (notch) is formed in the oxide film 16 formed on the surface 10s of the compressor blade 10 as a reference shape (reference line) that serves as an index for evaluating the state of the compressor impeller 6. In S101, for example, before the turbocharger 2 starts to operate (when the turbocharger 2 is new), the groove 18 is formed in the oxide film 16. In S101, the point P1 where the maximum principal stress σ1 of the compressor blade 10 occurs in the operating state of the turbocharger 2 and the direction d1 of the maximum principal stress σ1 are obtained in advance by analysis such as FEM, and the groove 18 may be formed in the oxide film 16 at the point P1 where the maximum principal stress σ1 occurs along the direction d2 perpendicular to the direction d1 of the maximum principal stress σ1. In the exemplary embodiment shown in FIG. 4, a groove 18 is formed on 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 from the halfway position of the blade height of the compressor blade 10). In this specification, the operating state of the turbocharger 2 means the state in which the turbocharger 2 is operating, and the operating state of the compressor 4, i.e., the state in which the compressor 4 is operating.

In S101, the grooves 18 in the compressor blades 10 may be formed, for example, by laser marking, microetching, or other known techniques. Also, in S101, as shown in FIG. 5, it is preferable that the grooves 18 are formed only in the oxide layer 16 so as not to damage the base material 14, but they may be formed to a depth that reaches the base material 14.

When the turbocharger 2 is operated after forming the groove 18 in S101, as the operating time of the turbocharger 2 increases, the position of the groove 18 and the width W of the groove 18 change due to the progression of creep of the base material 14, as shown in Figures 6 and 7. Figure 6 shows that as the operating time of the turbocharger 2 increases, the position of the groove 18 changes from the dotted line position to the solid line position so as to move away from the hub 9. Figure 7 shows that the width W of the groove 18 increases as the operating time of the turbocharger 2 increases. Note that as creep of the base material 14 progresses with the operation of the turbocharger 2, the oxide film 16 breaks starting from the groove 18, and the oxide film is regenerated by oxidizing the minutely elongated portion, so that an oxide film 16a thinner than the oxide film 16 formed in S101 is formed at the bottom of the groove 18.

In S102, as shown in FIG. 8, during regular inspection of the turbocharger 2 (when the turbocharger 2 is opened for inspection), a casing (not shown) covering the compressor impeller 6 is opened, and a replica 20 (replica 20 with the shape of the groove 18 in the oxide film 16 transferred thereto) of the portion in which the groove 18 is formed in the oxide film 16 is taken using a known replica method. For example, the replica 20 may be taken at each regular inspection of the turbocharger 2. The taken replica 20 is then measured to measure the width of the groove 18 at the time the replica 20 is taken. In the following, as shown in FIG. 9, the width of the groove 18 measured from the replica 20 taken during the i-th regular inspection of the turbocharger 2 (i is an integer equal to or greater than 1) is referred to as Wi. The dashed lines in FIG. 9 indicate the movement and change in shape of the groove 18 over time.

In S103, the change in width W of groove 18 from the time groove 18 was formed to the time of the i-th regular inspection (Wi-W0) is calculated from width W0 of groove 18 at the time groove 18 was formed in S101 (initial value of width W of groove 18) and width Wi of groove 18 measured from replica 20 taken during i-th (i is an integer equal to or greater than 1) regular inspection of turbocharger 2 in S103, and the remaining life condition of compressor impeller 6 is evaluated based on the calculated change in width (Wi-W0).

In this case, for example, correlation information R1 between the change in width of the groove 18 (Wi-W0) and the remaining life of the compressor impeller 6 may be acquired in advance, and the remaining life of the compressor impeller 6 at the time of the i-th regular inspection of the turbocharger 2 may be calculated based on the change in width of the groove 18 (Wi-W0) and the correlation information R1. For example, the compressor impeller 6 may be replaced when the change in width of the groove 18 (Wi-W0) exceeds a preset threshold value, and it may be determined that the compressor impeller 6 will continue to be used without being replaced when the change in width of the groove 18 (Wi-W0) is equal to or less than a preset threshold value. In addition, in S103, the remaining life of the compressor impeller 6 may be evaluated based on the change in width of the groove 18 (Wi-W0) and the progress of the oxide film 16a at the bottom of the groove 18. In this way, the "state related to 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 indicator for determining whether to continue using or replace the compressor impeller 6 when inspecting the turbocharger 2, or other states related to the remaining life of the compressor impeller 6.

Here, the effects of the above-mentioned method for evaluating the state of the compressor impeller 6 will be described.
As described above, the grooves 18 formed in the oxide film 16 in S101 are deformed due to the progress of creep as the operation time of the turbocharger 2 passes. Therefore, by evaluating the state of the remaining life of the compressor impeller 6 based on the shape of the grooves 18 at the time when the grooves 18 are formed in S101 and the change over time of the shape of the grooves 18 obtained from the replica 20 taken in S102, it is possible to accurately evaluate the state of the remaining life of the compressor impeller 6 that reflects the influence that the compressor impeller 6 received during the operation of the turbocharger 2. In addition, it is possible to appropriately evaluate whether or not to continue using the compressor impeller 6 when inspecting the turbocharger 2, and it is possible to optimize the limit use of the compressor impeller 6 and the replacement time of the compressor impeller 6.

In addition, 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, the condition of the remaining life caused by stress in the compressor impeller 6 can be accurately evaluated. In particular, by forming the groove 18 at the point P1 where the maximum principal stress σ1 occurs in the compressor blade 10 along the direction d2 perpendicular to the direction of the maximum principal stress σ1, the width W of the groove 18 expands in the direction of the maximum principal stress σ1 as the turbocharger 2 operates, making the expansion of the width W of the groove 18 clear and enabling reverse analysis of the stress state of the compressor impeller 6.

In addition, as the operating time of the turbocharger 2 progresses, the width W of the groove 18 on the surface of the compressor impeller 6 increases due to the progression of creep. Therefore, by evaluating the condition of the remaining life of the compressor impeller 6 based on the amount of change in the width of the groove 18 (Wi-W0), the condition of the remaining life of the compressor impeller can be accurately evaluated.

Next, another specific example of the method for evaluating the condition of the compressor impeller shown in FIG. 1 will be described with reference to FIGS.
FIG. 10 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 the range S1 in FIG.

In the example shown in FIG. 10, in S101, a reference mark 30 is formed on the oxide film 16 formed on the surface of the compressor blade 10 as a reference shape that serves as an index for evaluating the state of the compressor impeller 6. In S101, for example, before the start of operation of the turbocharger 2 (when the turbocharger 2 is new), the reference mark 30 is formed on the oxide film 16. In S101, the point P1 where the maximum principal stress σ1 of the compressor blade 10 occurs in the operating state of the turbocharger 2 and the direction d1 of the maximum principal stress σ1 are obtained in advance by analysis such as FEM, and the reference mark 30 may be formed at the point P1 where the maximum principal stress σ1 occurs. In the exemplary embodiment shown in FIG. 10, the reference mark 30 is formed on the negative pressure surface 12 of the compressor blade 10 on the blade root 11 side of the compressor blade 10 (the hub 9 side from the half position of the blade height of the compressor blade 10). The reference mark 30 may also be formed by, for example, laser marking, microetching, or other known methods. It is desirable to form the reference mark 30 only on the oxide film 16 so as not to scratch the base material 14 (see FIG. 3), but it may be formed to a depth that reaches the base material 14.

10, in S101, a reference mark 30 is formed including a circular groove 32 formed along a circle C1 and four linear grooves 34 extending linearly from the circular groove 32 toward the outer periphery of the circular groove 32. 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) perpendicular 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 turbocharger 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 turbocharger 2.

When the turbocharger 2 is operated after forming the reference mark 30 in S101, as shown in FIG. 12, as the cumulative operating time of the turbocharger 2 increases, creep of the base material 14 (see FIG. 3) progresses, causing the reference mark 30 to deform. Deformation of the reference mark 30 is not limited to the progression of creep, but can also occur when the compressor impeller 6 is damaged due to over-rotation of the turbocharger 2. In the example shown in FIG. 12, the shape of the reference mark 30 changes from the shape shown by the dashed line to the shape shown by the solid line.

In S102, during regular inspection of the turbocharger 2, a casing (not shown) covering the compressor impeller 6 is opened, and a replica (not shown replica with the shape of the reference mark 30 in the oxide film 16 transferred thereto) of the portion of the oxide film 16 on which the reference mark 30 is formed is taken using a known replica method. The above replica may be taken, for example, every time the turbocharger 2 is inspected regularly.

In S103, the shape of the reference mark 30 at the time when the reference mark 30 in S101 was formed (initial shape of the reference mark 30 when the turbocharger 2 is new) is compared with the shape of the reference mark 30 at the time of the i-th regular inspection obtained from the replica taken at the i-th regular inspection of the turbocharger 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 in S101 was formed to the time of the i-th regular inspection of the turbocharger 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 in S101 was formed to the time of the i-th regular inspection of the turbocharger 2 in S102, the remaining life status of the compressor impeller 6 at the time of the i-th regular inspection is evaluated.

Here, we will explain the effects of the compressor impeller condition evaluation method described using Figures 10 to 13, etc.

As described above, as the operation time of the turbocharger 2 elapses, the shape of the reference mark 30 on the surface of the compressor impeller 6 changes two-dimensionally due to the progression of creep. Therefore, based on the shape of the reference mark 30 at the time when the reference mark 30 was formed in S101 and the two-dimensional change in the shape of the reference mark 30 obtained from the replica 20 taken in S102 (two-dimensional change on the surface 10s of the compressor blade 10), the principal stress direction can be grasped and the deformation amount of the reference mark 30 along the principal stress direction can be grasped, and the condition regarding the remaining life of the compressor impeller 6 can be accurately evaluated. In addition, 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 the stress state of the compressor impeller 6 can be reverse-analyzed. In addition, it is possible to appropriately evaluate whether or not to continue using the compressor impeller 6 during regular inspection of the turbocharger 2, and it is possible to optimize the limit use of the compressor impeller 6 and the replacement time of the compressor impeller 6.

In particular, the state of the remaining life of the compressor impeller 6 can be accurately evaluated by determining the principal stress direction based on the deformation of the circular groove 32 in the reference mark 30 (in the example shown in Figure 13, the deformation gradually flattens from a circle) and determining the deformation (twist) in the rotational direction of the reference mark 30 around the center of the circular groove 32 based on the change in the inclination of the linear groove 34.

In addition, since the four linear grooves 34 are arranged around the circular groove 32 along the two mutually perpendicular straight lines L1 and L2, the deformation of the reference mark 30 can be clearly grasped. This allows the condition of the compressor impeller 6 regarding its remaining life to be evaluated with high accuracy. In particular, by making the straight line L1 a straight line along the direction of the maximum principal stress σ1 of the compressor blade 10 in the operating state of the turbocharger 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. This allows the condition of the compressor impeller 6 regarding its remaining life to be evaluated with high accuracy.

The present disclosure is not limited to the above-described embodiments, but also includes variations of the above-described embodiments and appropriate combinations of these embodiments.

For example, a remaining life evaluation method in which several pieces of data that affect the remaining life of the turbocharger 2, such as engine data showing the operating state of the engine, are acquired in real time as online data and the remaining life of the impeller is evaluated in real time based on the online data may be combined with the compressor impeller condition evaluation method described above in the present disclosure. In this case, the remaining life of the compressor impeller evaluated using the replica described above during regular inspection of the turbocharger 2 may be used to correct the remaining life of the compressor impeller evaluated in real time based on online data after regular inspection of the turbocharger 2. This allows the condition of the remaining life of the compressor impeller 6 to be evaluated with even greater accuracy.

In addition, in some of the above-mentioned embodiments, the range S1 in FIG. 2 is shown as an example of the location where the reference shape is set in S101, but the reference shape may be set at multiple locations, for example, in the range S2 near the trailing edge of the compressor blade 10 in FIG. 2. The reference shape may also be set for each compressor blade 10. The reference shape may also be formed on the pressure surface of the compressor blade 10 or on the tip side of the compressor blade 10. By setting the reference shape at multiple locations, the results of the analysis in advance can be verified, leading to improved analysis accuracy in the future. In addition, the overall deformation (creep form) of the compressor impeller 6 due to aging operation can be grasped. In addition, by setting the reference shape at the tip side of the compressor blade 10, the effect of the temperature gradient of the compressor impeller 6 can be verified. For example, by setting the reference shape at each of the tip side and the blade root side of the compressor blade 10, the effect of the temperature gradient in the blade height direction of the compressor blade 10 during operation of the compressor 4 can be verified. In addition, for example, by providing multiple reference shapes at intervals in the air flow direction on the compressor blades 10, it is possible to verify the effect of the temperature gradient in the air flow direction while the compressor 4 is operating.

The contents described in each of the above embodiments can be understood, for example, as follows:

(1) A method for evaluating a condition of a compressor impeller according to at least one embodiment of the present disclosure,
A compressor impeller condition evaluation method for evaluating a condition related to a remaining life of a compressor impeller (e.g., the above-mentioned compressor impeller 6) included in a compressor (e.g., the above-mentioned compressor 4), comprising:
a reference shape forming step of forming a reference shape (e.g., the above-mentioned groove 18 or the reference mark 30) serving as an index for evaluating a state regarding a remaining life of the compressor impeller in a coating (e.g., the above-mentioned oxide coating 16) formed on the surface of the compressor impeller;
a replica taking step of taking a replica (e.g., the replica 20 described above) to which the reference shape of the coating is transferred during inspection of the compressor;
a condition evaluation step of evaluating a condition regarding a remaining life of the compressor impeller based on a 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 taken in the replica taking step;
Equipped with.

According to the compressor impeller condition evaluation method described in (1) above, the reference shape formed on the coating in the reference shape formation step is deformed due to the progression of creep as the compressor operation time passes. Therefore, by taking a replica to which the reference shape is transferred during compressor inspection and evaluating the condition of the compressor impeller's remaining life based on the change in the reference shape, it is possible to accurately evaluate the condition of the compressor impeller's remaining life, which reflects the influence the compressor impeller received during compressor operation. In addition, it is possible to appropriately evaluate whether or not to continue using the compressor impeller during compressor inspection, making it possible to optimize the limit of use of the compressor impeller and the replacement time of the compressor impeller.

(2) In some embodiments, in the compressor impeller condition evaluation method described in (1) above,
In the reference shape forming step, the reference shape is formed on a blade root side (for example, the above-mentioned blade root 11 side) of a compressor blade (for example, the above-mentioned compressor blade 10).

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

(3) In some embodiments, in the compressor impeller condition evaluation method described in (1) or (2) above,
In the reference shape forming step, the reference shape is formed at a location (for example, the above-mentioned location P1) where the maximum principal stress of the compressor blade occurs when the compressor is in an operating state.

According to the compressor impeller condition evaluation method described in (3) above, by forming a reference shape at the location where the maximum principal stress occurs in the compressor blade, it is possible to accurately evaluate the condition of the compressor impeller with respect to the remaining life caused by stress.

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

According to the compressor impeller condition evaluation method described in (4) above, as the compressor operating time passes, the width of the grooves on the surface of the compressor impeller increases due to the progression of creep. Therefore, by evaluating the condition of the compressor impeller regarding the remaining life based on the change in the groove width, the condition of the compressor impeller regarding the remaining life can be evaluated with high accuracy.

(5) In some embodiments, in the compressor impeller condition evaluation method described in (4) above,
In the reference shape forming step, the groove is formed along a direction perpendicular to a direction of maximum principal stress of the compressor blade in an operating state of the compressor.

According to the compressor impeller condition evaluation method described in (5) above, by forming a groove along a direction perpendicular to the direction of the maximum principal stress of the compressor blades when the compressor is in operation, the condition of the compressor impeller regarding the remaining life can be accurately evaluated based on the amount of change in the width of the groove, which reflects the effect of the maximum principal stress during compressor operation.

(6) In some embodiments, in the compressor impeller condition evaluation method according to any one of (1) to (3) above,
In the reference shape forming step, a reference mark (e.g., the above-mentioned reference mark 30) is formed as the reference shape in the coating,
The condition evaluation step evaluates a condition regarding a remaining life of the compressor impeller based on a change in a shape of the reference mark.

According to the compressor impeller condition evaluation method described in (6) above, as the compressor operating time passes, the shape of the reference mark on the surface of the compressor impeller changes two-dimensionally due to the progression 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 condition of the compressor impeller regarding the remaining life can be evaluated with high accuracy.

(7) In some embodiments, in the compressor impeller condition evaluation method described in (6) above,
In the reference shape forming step, a reference mark is formed that includes a circular groove formed along a circle and at least one linear groove (e.g., the four linear grooves 34 described above) extending linearly from the circular groove toward the outer periphery of the circular groove.

According to the compressor impeller condition evaluation method described in (7) above, the principal stress direction can be determined 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 determined based on the change in the inclination of the linear groove. This allows the condition of the compressor impeller regarding its remaining life to be evaluated with high accuracy.

(8) In some embodiments, in the compressor impeller condition evaluation method described in (7) above,
In the reference shape forming step, a reference mark including the circular groove and four linear grooves extending linearly toward an outer periphery side of the circular groove is formed,
the four linear grooves are spaced at 90 degree intervals around the center of the circular groove;
The four linear grooves include two linear grooves (e.g., the two linear grooves 34a described above) formed along a first straight line (e.g., the above-mentioned first straight line L1) and two linear grooves (e.g., the two linear grooves 34b described above) formed along a second straight line (e.g., the above-mentioned second straight line L2) perpendicular to the first straight line.

According to the compressor impeller condition evaluation method described in (8) above, four linear grooves are arranged around the circular groove along two mutually perpendicular straight lines, so that the deformation of the reference mark can be clearly grasped. This allows the condition of the compressor impeller regarding its remaining life to be evaluated with high accuracy.

(9) In some embodiments, in the compressor impeller condition evaluation method described in (8) above,
The two linear grooves formed along the first straight line are formed along a direction of maximum principal stress of the compressor blade of the compressor impeller in an operating state of the compressor.

According to the compressor impeller condition evaluation method described in (9) above, the deformation of the reference mark in the direction along the principal stress can be clearly grasped. This allows the condition of the compressor impeller regarding its remaining life to be evaluated with high accuracy.

2 Turbocharger 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 (6)

A compressor impeller condition evaluation method for evaluating a condition related to a remaining life of a compressor impeller included in a compressor, comprising:
a reference shape forming step of forming a reference shape, which serves as an index for evaluating a state regarding a remaining life of the compressor impeller, on the coating formed on the surface of the compressor impeller;
a replica taking step of taking a replica having the reference shape of the coating transferred thereto during inspection of the compressor;
a condition evaluation step of evaluating a condition regarding a remaining life of the compressor impeller based on a 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 taken in the replica taking step;
Equipped with
In the reference shape forming step, a groove is formed as the reference shape in the coating,
The condition evaluation step evaluates a condition regarding a remaining life of the compressor impeller based on a change in the width of the groove, and
A compressor impeller condition evaluation method, wherein in the reference shape forming step, the groove is formed along a direction perpendicular to a direction of maximum principal stress of the compressor blade in an operating state of the compressor. A compressor impeller condition evaluation method for evaluating a condition related to a remaining life of a compressor impeller included in a compressor, comprising:
a reference shape forming step of forming a reference shape, which serves as an index for evaluating a state regarding a remaining life of the compressor impeller, on the coating formed on the surface of the compressor impeller;
a replica taking step of taking a replica having the reference shape of the coating transferred thereto during inspection of the compressor;
a condition evaluation step of evaluating a condition regarding a remaining life of the compressor impeller based on a 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 taken in the replica taking step;
Equipped with
In the reference shape forming step, a reference mark is formed as the reference shape in the coating,
The condition evaluation step evaluates a condition regarding a remaining life of the compressor impeller based on a change in the shape of the reference mark, and
A method for evaluating the condition of a compressor impeller, wherein the reference shape forming step forms a reference mark including a circular groove formed along a circle and at least one linear groove extending linearly from the circular groove toward the outer periphery of the circular groove. The compressor impeller condition evaluation method according to claim 1 or 2 , wherein in the reference shape forming step, the reference shape is formed on a root side of a compressor blade. 3. The compressor impeller condition evaluation method according to claim 1 , wherein in the reference shape forming step, the reference shape is formed at a position where a maximum principal stress occurs in a compressor blade in an operating state of the compressor. In the reference shape forming step, a reference mark including the circular groove and four linear grooves extending linearly toward an outer periphery side of the circular groove is formed,
the four linear grooves are spaced at 90 degree intervals around the center of the circular groove;
3. The compressor impeller condition evaluation method 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 perpendicular to the first straight line. The compressor impeller condition evaluation method according to claim 5 , wherein the two linear grooves formed along the first straight line are formed along a direction of maximum principal stress of the compressor blade in an operating state of the compressor.

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