JP6768007B2 - Shroud structure and turbocharger - Google Patents

Description

The present invention relates to a shroud structure and a turbocharger installed in a turbocharger.

Generally, for example, the turbine side of a turbocharger includes an impeller 102 having a blade 100 and a metal shroud 104 covering the blade 100 of the impeller 102, as shown in FIG. Normally, it suffices if the impeller 102 can be rotated by the pressure of the exhaust gas flowing in from the exhaust inlet and the rotational energy can be recovered by the compressor. However, there is a problem that the exhaust gas passes through the gap (clearance d) between the shroud 104 and the impeller 102 without rotating the impeller 102, and the energy recovery rate is lowered. This problem also occurs between the impeller 102 on the compressor side and the shroud 104. Therefore, conventionally, efforts have been made to reduce the clearance d between the impeller 102 and the shroud 104 as much as possible.

For example, in Japanese Patent No. 369846, the above clearance is almost zero by adopting a sliding member made of a resin that does not wear the metal material as a part of the shroud (abrasive seal) on the compressor side. I have to.

Japanese Patent Application Laid-Open No. 2-196109 describes an example in which a ceramic seal layer bonded with a porous ceramic is bonded to a metal shroud via an intermediate layer that absorbs a difference in thermal expansion. Further, in Japanese Patent Application Laid-Open No. 6-39820, shrink-fitting is studied.

By the way, in the method described in Japanese Patent No. 369846, a sliding member made of resin is adopted as a part of the shroud on the compressor side. Since the compressor side has a lower temperature (about 200 ° C.) than the turbine side, a resin sliding member can be used. However, since the turbine side has a high temperature (800 ° C. or higher), the resin sliding member does not have heat resistance.

In the method described in JP-A-2-196109, a ceramic seal layer is used as an abradable seal on a metal shroud. However, when the temperature is raised from room temperature to a high temperature, thermal stress is generated due to the difference in thermal expansion coefficient between ceramic and metal. As a result, cracks or peeling may occur at the bonding interface between the shroud and the ceramic seal layer, and the positions may shift. In this case, the clearance between the impeller and the shroud, which is the original purpose, cannot be reduced. An intermediate layer is interposed to relieve the thermal stress, but there is also a problem that the thermal stress is too large to be relieved.

In the method described in JP-A-6-39820, shrink fitting is studied. However, when the temperature is raised from room temperature to a high temperature, the metal member swells greatly, while the ceramic member hardly swells, so that a gap is generated between the metal member and the ceramic member. In this case, the ceramic member may be misaligned, and the clearance between the impeller and the shroud, which is the original purpose, may not be reduced. In some cases, the clearance may be further increased due to interference with the impeller due to the displacement of the rotation axis and wear.

As described above, although it is desired to fix the ceramic member to the metal member while keeping the clearance small, there is a problem in both of the above two methods of chemically and physically fixing (joining) the ceramic member.

The present invention has been made in consideration of such a problem, and the metal shroud is provided with a ceramic member, and the clearance between the impeller and the shroud is reduced to almost zero before and after the temperature rise. It is an object of the present invention to provide a shroud structure that can be maintained and can suppress a decrease in energy recovery rate in a turbocharger.

The present invention also provides a turbocharger capable of maintaining the clearance between the impeller and the shroud at a clearance close to zero before and after the temperature rise and suppressing a decrease in energy recovery rate. The purpose.

[1] The first shroud structure according to the present invention is a shroud structure having a metal shroud covering a blade among impellers that are rotationally driven by exhaust pressure, and the shroud and the shroud. a ceramic member which is attached to position blade facing the impeller, said ceramic member possess a pressing member pressing towards the shroud, the shroud has at least one in a portion where the ceramic member is attached Having a first inclined surface, the ceramic member has at least one second inclined surface facing the first inclined surface of the shroud, and the ceramic member corresponds to pressing by the pressing member. The second inclined surface is slidable along the first inclined surface of the shroud .

[2] before Symbol first inclined surface and the second inclined surface preferably has the same angle with respect to the pressing direction by the pressing member.

[3] before the first inclined surface and the second inclined surface SL may have the pressing angle of less than 90 ° beyond the 0 ° to the direction pressing by members.

[ 4 ] The second shroud structure according to the present invention is a shroud structure having a metal shroud covering a blade among the imperers that are rotationally driven by the pressure of the exhaust, and the shroud and the shroud. It has a ceramic member attached at a position facing the blade of the impeller and a pressing member that presses the ceramic member toward the shroud, and the pressing member is attached to the blade of the impeller among the ceramic members. The non-opposing exposed surface is pressed, and the pressing member has a metal member that is in contact with the exposed surface of the ceramic member and is fixed to the shroud at a low temperature portion, and the metal member holds the shroud. It is characterized by having a thermal expansion coefficient higher than the thermal expansion coefficient of the constituent metal material.

[5] before Symbol shroud, said of the metal member may have a member for fixing the contact to the exposed surface a surface opposite to the surface of the ceramic member.

[6] before Symbol shroud has a first projecting portion projecting toward the metal member, the metal member has a second projecting portion projecting toward the shroud, the pressing member further , The clamp member that fastens the tip of the first overhang and the tip of the second overhang may be provided.

[7] Before SL shroud has a plurality of said first inclined surface, wherein the ceramic member has a plurality of said second inclined surface, and has a step between a plurality of the second inclined surface , The step may extend in a direction away from the exposed surface.

[ 8 ] The third shroud structure according to the present invention is a shroud structure having a metal shroud covering the blades among the impellers rotationally driven by the pressure of the exhaust, and the shroud and the shroud. It has a ceramic member attached at a position facing the blade of the impeller and a pressing member that presses the ceramic member toward the shroud, and the porosity of the ceramic member is 1 to 80%. the porosity of the member, the porosity of the shroud facing the portion, and wherein the lower porosity of the blade portion opposite to the impeller.

[ 9 ] The fourth shroud structure according to the present invention is a shroud structure having a metal shroud covering a blade among impellers that are rotationally driven by exhaust pressure, and is one of the shroud and the shroud. It has a ceramic member attached at a position facing the blade of the impeller and a pressing member that presses the ceramic member toward the shroud, and a lubricant is interposed between the shroud and the ceramic member. It is characterized by that .

[10] The pressing direction by the pressing member may be along the axial direction of the impeller and away from the impeller.
[11] The pressing direction by the pressing member may be along the axial direction of the impeller and in the direction toward the impeller.
[12] The coefficient of thermal expansion of the ceramic member is preferably 0.1 to 18.0 × ^10-6 / K.
[ 13 ] The fifth turbocharger according to the present invention is characterized by having the shroud structure in a turbocharger having an impeller that is rotationally driven by exhaust pressure and a metal shroud that covers the blades of the impeller. And.

[ 14 ] In the fifth aspect of the present invention, the impeller may be a turbine impeller installed on the turbine side, and the shroud may be a turbine shroud installed on the turbine.

According to the shroud structure according to the present invention, the metal shroud is provided with a ceramic member, and the clearance between the impeller and the shroud can be maintained at a clearance close to zero before and after the temperature rise. It is possible to suppress a decrease in the energy recovery rate in the charger.

According to the turbocharger according to the present invention, the clearance between the impeller and the shroud can be maintained at a clearance close to zero before and after the temperature rise, and a decrease in the energy recovery rate can be suppressed.

FIG. 1 is a cross-sectional view showing a schematic configuration of a turbocharger according to the present embodiment with a part omitted. FIG. 2A is a cross-sectional view showing a shroud structure (first shroud structure) according to the first embodiment. FIG. 2B is a cross-sectional view showing a turbine shroud of the first shroud structure. FIG. 2C is a cross-sectional view showing a ceramic member of the first shroud structure. FIG. 3A is a cross-sectional view showing a state of the first shroud structure before the temperature rise, with a part omitted. FIG. 3B is a cross-sectional view showing a state of the first shroud structure after the temperature rise is partially omitted. FIG. 4A is a cross-sectional view showing a first shroud structure including the first pressing member with a part omitted. FIG. 4B is a cross-sectional view showing a first shroud structure provided with a second pressing member with a part omitted. FIG. 5A is a cross-sectional view showing a shroud structure (second shroud structure) according to the second embodiment partially omitted. FIG. 5B is a cross-sectional view showing a turbine shroud of the second shroud structure. FIG. 5C is a cross-sectional view showing a ceramic member of the second shroud structure. FIG. 6A is a cross-sectional view showing a shroud structure (third shroud structure) according to the third embodiment, with a part omitted. FIG. 6B is a cross-sectional view showing a turbine shroud of the third shroud structure. FIG. 6C is a cross-sectional view showing a ceramic member of the third shroud structure. FIG. 7A is a cross-sectional view showing a state of the third shroud structure before the temperature rise, with a part omitted. FIG. 7B is a cross-sectional view showing a state of the third shroud structure after the temperature rise is partially omitted. FIG. 8A is a cross-sectional view showing the configuration of the ceramic member 1 (or the ceramic member 2) according to the first embodiment. FIG. 8B is a cross-sectional view showing the structure of the metal cylinder according to the first embodiment. FIG. 8C is a cross-sectional view showing a state in which the ceramic member 1 (or the ceramic member 2) is fitted to the inner peripheral surface of the metal cylinder in the first embodiment. FIG. 9A is a cross-sectional view showing the configuration of the ceramic member 1 (or the ceramic member 2) according to Comparative Example 1. FIG. 9B is a cross-sectional view showing the structure of the metal cylinder according to Comparative Example 1. FIG. 9C is a cross-sectional view showing a state in which the ceramic member 1 (or the ceramic member 2) is fitted to the inner peripheral surface of the metal cylinder in Comparative Example 1. It is explanatory drawing which shows the operation on the turbine side, for example, of a conventional turbocharger.

Hereinafter, examples of embodiments of the shroud structure and turbocharger according to the present invention will be described with reference to FIGS. 1 to 9C.

First, as shown in FIG. 1, the turbocharger 10 according to the present embodiment has a metal turbine impeller 12 that is rotationally driven by exhaust pressure on the turbine side, and a blade 14 portion of the turbine impeller 12. A metal turbine shroud 16 is installed to cover the above. On the compressor side, a metal compressor impeller 20 connected to the turbine impeller 12 via a rotor shaft 18 and a metal compressor shroud 24 covering the blade 22 of the compressor impeller 20 are installed. There is.

In the turbocharger 10, the turbine impeller 12 rotates due to the pressure of the exhaust gas flowing in from the exhaust inlet (not shown). The rotational force of the turbine impeller 12 is transmitted to the compressor impeller 20 via the rotor shaft 18, and the fresh air taken in from the fresh air inlet (not shown) passes through the flow path between the plurality of blades 22 provided in the compressor impeller 20. , Compressed and pumped to the internal combustion engine.

Then, the shroud structure 50A (hereinafter, the first shroud structure 50A) according to the first embodiment is installed on the turbine side, for example, as shown in FIG. 2A, and the above-mentioned metal turbine shroud 16 is installed. An annular ceramic member 52 attached to the turbine shroud 16 at a position facing the blade 14 of the turbine imperer 12, and a pressing member 54 (see FIG. 3A) that presses the ceramic member 52 toward the turbine shroud 16. Have.

For example, when the ceramic member 52 is attached to the turbine shroud 16 at room temperature, the ceramic member 52 is attached to the turbine shroud 16 as shown in FIG. 2B. However, as will be described later, when the temperature around the turbine shroud 16 becomes high and the turbine shroud 16 thermally expands, the ceramic member 52 slides with respect to the turbine shroud 16 (see FIG. 3B).

The turbine shroud 16 has at least one first inclined surface 58 at the portion where the ceramic member 52 is attached. The ceramic member 52 has at least one second inclined surface 60 facing the first inclined surface 58 of the turbine shroud 16.

The first inclined surface 58 provided on the turbine shroud 16 and the second inclined surface 60 provided on the ceramic member 52 have the same angle θ with respect to the pressing direction by the pressing member 54. In the first shroud structure 50A, the first inclined surface 58 and the second inclined surface 60 have an angle of more than 0 ° and less than 90 °, preferably 30 °, with respect to the pressing direction (see FIG. 3A) by the pressing member 54. It has an angle of ° or more and less than 90 °, more preferably an angle of 60 ° or more and less than 90 °.

As shown in FIG. 3A, the pressing direction by the pressing member 54 is a direction along the axial direction of the turbine impeller 12 and away from the turbine impeller 12. Further, the pressing member 54 presses the exposed surface 56 of the ceramic member 52 that does not face the blade 14 of the turbine impeller 12. A specific configuration example of the pressing member 54 will be described later.

As described above, by installing the ceramic member 52 in the turbine shroud 16 at a position facing the blade 14 of the turbine impeller 12, a constant clearance is provided between the blade 14 of the turbine impeller 12 and the ceramic member 52. d, that is, a clearance d close to zero is maintained.

Then, as shown in FIG. 3B, when the temperature rises in the turbine shroud 16 and its surroundings due to the flow of high-temperature exhaust gas, the turbine shroud 16 expands in the radial direction due to thermal expansion. That is, the outer diameter and the inner diameter become large. At this time, since the ceramic member 52 has a small coefficient of thermal expansion, it hardly expands. Moreover, the ceramic member 52 is pressed toward the turbine shroud 16 by the pressing member 54. Therefore, the second inclined surface 60 of the ceramic member 52 slides along the first inclined surface 58 of the turbine shroud 16 and maintains the shape before the temperature rise against the expansion of the turbine shroud 16. That is, the ceramic member 52 maintains the position before the temperature rise without peeling or breaking. As a result, even if the temperature of the turbine shroud 16 and its surroundings becomes high, a clearance d close to zero is maintained between the blade 14 of the turbine impeller 12 and the ceramic member 52, and the energy associated with the expansion of the clearance d is maintained. It is possible to suppress a decrease in recovery rate.

In particular, the first inclined surface 58 provided on the turbine shroud 16 and the second inclined surface 60 provided on the ceramic member 52 have the same angle θ with respect to the pressing direction by the pressing member 54. Therefore, the second inclined surface 60 of the ceramic member 52 can smoothly slide with respect to the first inclined surface 58 of the turbine shroud 16, and the occurrence of cracks or the like in the ceramic member 52 can be suppressed. Further, although not shown, by interposing a lubricant between the first inclined surface 58 of the turbine shroud 16 and the second inclined surface 60 of the ceramic member 52, the second inclined surface 60 of the ceramic member 52 is further formed. The turbine shroud 16 can be smoothly slid with respect to the first inclined surface 58.

Further, the pressing member 54 presses the exposed surface 56 of the ceramic member 52 that does not face the blade 14 of the turbine impeller 12. Therefore, the pressing member 54 can press the ceramic member 52 toward the turbine shroud 16 without hindering the rotation of the turbine impeller 12.

Here, some configuration examples of the pressing member 54 will be described with reference to FIGS. 4A and 4B.

First, as shown in FIG. 4A, the pressing member according to the first configuration example (hereinafter referred to as the first pressing member 54A) comes into contact with the exposed surface 56 of the ceramic member 52 and is a turbine shroud in the low temperature region 64. It has an annular metal member 62 fixed to 16. The metal member 62 has a coefficient of thermal expansion higher than the coefficient of thermal expansion of the metal material constituting the turbine shroud 16.

Since high-temperature exhaust gas is supplied to the turbine impeller 12, the turbine impeller 12 and its peripheral portion become hot. Specifically, the high temperature region 66 is a tubular region (indicated by a two-dot chain line) whose diameter is substantially the same as the outer diameter of the turbine impeller 12. The farther away from the high temperature region 66, the lower the temperature. Therefore, the outside of the high temperature region 66 can be referred to as a portion where the temperature is hardly raised by the supplied exhaust gas, that is, the low temperature region 64.

On the other hand, the turbine shroud 16 has a fixing member 68 for fixing a surface of the metal member 62 opposite to the surface of the ceramic member 52 in contact with the exposed surface 56. The fixing member 68 is formed integrally with the turbine shroud 16, for example, an annular outer wall 68a extending from the outer peripheral portion of the turbine shroud 16 toward the compressor side, and an annular fixing wall extending from the end of the outer wall 68a toward the turbine impeller 12. It has 68b and. The metal member 62 is installed in an annular space formed between the exposed surface 56 of the ceramic member 52, the inner surface of the outer wall 68a of the fixing member 68, and the fixing wall 68b of the fixing member 68.

Since the coefficient of thermal expansion of the metal member 62 is higher than the coefficient of thermal expansion of the metal material constituting the turbine shroud 16, the metal member 62 expands to some extent even if the turbine shroud 16 hardly expands. The member 52 can be pressed toward the turbine shroud 16. Of course, even at room temperature, the metal member 62 presses the ceramic member 52 toward the turbine shroud 16. The metal member 62 may have a coefficient of thermal expansion higher than the coefficient of thermal expansion of the metal material constituting the turbine shroud 16, and may be a metal material different from the metal material constituting the turbine shroud 16 or the same type of metal material. Good.

Next, as shown in FIG. 4B, the pressing member (hereinafter, referred to as the second pressing member 54B) according to the second configuration example is a metal member 62 similar to the metal member 62 of the first pressing member 54A described above. It is the same in terms of use, but differs in the following points.

That is, the turbine shroud 16 has a first overhanging portion 70 that projects from the rear portion (compressor side) toward the metal member 62 and in a direction away from the high temperature region 66.

The metal member 62 has a thick flange portion 72 at the rear portion (compressor side), and the thin tubular portion 74 protruding from the flange portion 72 toward the exposed surface 56 of the ceramic member 52, and the flange portion 72. It has a second overhanging portion 76 that projects from the boundary portion of the tubular portion 74 toward the first overhanging portion 70 of the turbine shroud 16 and in a direction away from the high temperature region 66.

Further, the second pressing member 54B has a clamp member 78 that fastens the tip of the first overhang 70 and the tip of the second overhang 76 in the low temperature region 64. As the clamp member 78, for example, a commercially available clamp center ring or the like can be used.

By fastening the tip of the first overhang 70 and the tip of the second overhang 76 in this way, the metal member 62 can be fixed to the turbine shroud 16 in the low temperature region 64. In particular, since the fastening can be performed in the low temperature region 64 which is separated from the high temperature region 66, there is an advantage that the fastening force is not easily loosened.

In this case as well, the coefficient of thermal expansion of the metal member 62 is higher than the coefficient of thermal expansion of the metal material constituting the turbine shroud 16. Therefore, even if the turbine shroud 16 hardly expands, the metal member 62 expands to some extent, so that the ceramic member 52 can be pressed toward the turbine shroud 16 through the tubular shape of the metal member 62. .. Even at room temperature, the metal member 62 presses the ceramic member 52 toward the turbine shroud 16. Further, similarly to the first pressing member 54A, the metal member 62 only needs to have a coefficient of thermal expansion higher than the coefficient of thermal expansion of the metal material constituting the turbine shroud 16, and is a metal material different from the metal material constituting the turbine shroud 16. It may be the same kind of metal material.

Next, the shroud structure according to the second embodiment (hereinafter, referred to as the second shroud structure 50B) will be described with reference to FIGS. 5A and 5B.

The second shroud structure 50B has substantially the same structure as the first shroud structure 50A described above, but differs in the following points.

That is, as shown in FIGS. 5A to 5C, the turbine shroud 16 has two first inclined surfaces 58 (a first inclined surface 58a on the outer peripheral side and a first inclined surface 58b on the inner peripheral side). The ceramic member 52 has two second inclined surfaces 60 (a second inclined surface 60a on the outer peripheral side and a second inclined surface 60b on the inner peripheral side). Further, the ceramic member 52 has a step 80 between the two second inclined surfaces 60. The step 80 extends in a direction away from the exposed surface 56. With these configurations, the radial length da of the first inclined surface 58a on the outer peripheral side facing the exposed surface 56 can be reduced. Therefore, when the thermal expansion of the ceramic member 52 is also taken into consideration, the amount of change due to the lateral thermal expansion of the ceramic member 52 becomes small.

If the amount of change due to thermal expansion of the ceramic member 52 is large, the size and material of the metal member 62 must be selected in consideration of the amount of change of the metal member 62 and the amount of change of the ceramic member 52. On the other hand, if the amount of change in the ceramic member 52 is small, the dimensions and materials of the metal member 62 need to be selected in consideration of only the thermal expansion of the metal member 62, so that various materials can be selected and the design is free. It is possible to increase the degree of freedom and reduce material costs. In the examples of FIGS. 5A and 5B, an example in which the first pressing member 54A is adopted is shown, but the same effect can be obtained by adopting the second pressing member 54B (see FIG. 4B).

Next, the shroud structure (hereinafter referred to as the third shroud structure 50C) according to the third embodiment will be described with reference to FIGS. 6A to 7B.

As shown in FIGS. 6A to 6C and 7A, the third shroud structure 50C has substantially the same structure as the first shroud structure 50A described above, but differs in the following points.

That is, the turbine shroud 16 has a structure in which the thickness gradually increases toward the turbine impeller 12 (see FIG. 7A), and the inner peripheral surface itself constitutes the first inclined surface 58. The ceramic member 52 is installed in the turbine shroud 16, and its outer peripheral surface itself constitutes the second inclined surface 60. As shown in FIGS. 7A and 7B, the pressing member 54 presses the exposed surface 56 of the ceramic member 52 that does not face the blade 14 of the turbine impeller 12, but in this case, the pressing direction is that of the turbine impeller 12. Along the axial direction and toward the turbine impeller 12.

The first inclined surface 58 and the second inclined surface 60 have the same angle with respect to the pressing direction by the pressing member 54, and have an angle of more than 0 ° and less than 90 °, preferably an angle of 30 ° or more and less than 90 °. More preferably, it has an angle of 60 ° or more and less than 90 °.

Then, as shown in FIG. 7B, the ceramic member 52 is pressed toward the turbine shroud 16 by the pressing member 54. Therefore, when the turbine shroud 16 expands in the radial direction due to thermal expansion, the second inclined surface 60 of the ceramic member 52 slides along the first inclined surface 58 of the turbine shroud 16 against the expansion of the turbine shroud 16. Maintain the shape before heating. That is, the ceramic member 52 maintains the position before the temperature rise without breaking. As a result, even if the temperature of the turbine shroud 16 and its surroundings becomes high, a clearance d close to zero is maintained between the blade 14 of the turbine impeller 12 and the ceramic member 52, and the energy associated with the expansion of the clearance d is maintained. It is possible to suppress a decrease in recovery rate.

As a configuration example of the pressing member 54, the above-mentioned first pressing member 54A or second pressing member 54B can be preferably adopted.

In the first shroud structure 50A to the third shroud structure 50C described above, the porosity of the ceramic member 52 is 1 to 80%, preferably 10 to 70%, and more preferably 20 to 60%. If the porosity is low, that is, if it is dense, the ceramic member 52 cannot be scraped by the blade 14 of the turbine impeller 12, and the blade 14 of the turbine impeller 12 may be damaged. On the contrary, if the porosity is too high, the mechanical strength is weakened, and there is a risk of damage due to pressing by the pressing member 54.

Further, regarding the porosity of the ceramic member 52, it is preferable that the porosity of the portion facing the turbine shroud 16 is lower than the porosity of the portion facing the blade 14 of the turbine impeller 12. If the porosity of the portion facing the turbine shroud 16 is high, the ceramic member 52 may be scraped when it is attached to the turbine shroud 16 and the dimensions may change. If the porosity of the portion of the turbine impeller 12 facing the blade 14 is low, the blade 14 may be damaged.

The coefficient of thermal expansion of the ceramic member 52 is 0.1 to 18.0 × ^10-6 / K, preferably 0.5 to 11.0 × ^10-6 / K, and more preferably 1 to 5.0 × 10 ^{−. It is 6} / K. If the coefficient of thermal expansion is too low, the dimensional difference from the turbine shroud 16 (made of metal) with a high coefficient of thermal expansion will widen when the temperature rises, and the first inclined surface 58 and the second inclined surface 60 will slide together. There is a risk that the dimensional difference cannot be absorbed. Further, if the coefficient of thermal expansion is too high, cracks may occur due to the thermal stress generated by the temperature difference of the ceramic member 52 itself when the temperature is raised.

The constituent material of the ceramic member 52 is silicon nitride, sialon, zirconia, cordierite, silicon carbide, or a machinable ceramic such as mica, talc, titanium silicon carbide, boron nitride, or a mixture containing at least one of these materials. Can be preferably adopted.

For metal parts such as the turbine shroud 16 and the turbine impeller 12, it is preferable to use heat-resistant cast steel or the like, nickel alloys such as Inconel (registered trademark) and Hastelloy (registered trademark). Since it has high heat resistance, it is suitable for use in a high temperature (800 ° C or higher) environment.

With respect to Examples 1 to 12 and Comparative Example 1, peeling and cracking of the ceramic member were confirmed.

(Example 1)
[Manufacturing of ceramic member 1]
Yttria partially stabilized zirconia powder is uniaxially press-molded, CIP (cold isotropic pressurization method) is applied to prepare cylindrical pellets, and then calcined in an air atmosphere at 1200 ° C. for 2 hours to make it porous. A ceramic cylinder was obtained. By machining this, as shown in FIG. 8A, the outer diameter of one end is φ30 mm, the outer diameter of the other end is φ70 mm, and the inner diameter is constant φ30 mm from one end to the other end. Then, a cylindrical ceramic member 1 having a distance (height) of 20 mm from one end to the other was obtained. The inclination angle of the outer peripheral surface is 45 °.

The porosity of the ceramic member 1 was 50% as measured by the Archimedes method (JIS1634-1998). The coefficient of thermal expansion was 10.5 × ^10-6 / K as measured according to JIS1618-2002.

[Manufacturing of ceramic member 2]
The yttria partially stabilized zirconia powder was mixed with a solvent, poured into a mold, dried, and fired at 1200 ° C. for 2 hours to obtain a ceramic member 2 having the same shape as the ceramic member 1 described above. Similarly to the ceramic member 1, the ceramic member 2 also had a porosity of 50% and a coefficient of thermal expansion of 10.5 × ^10-6 / K.

[Metal cylinder]
As shown in FIG. 8B, a metal cylinder having an inner diameter that expands from one end to the other is prepared. The inner diameter of one end is φ10 mm, and the inner diameter of the other end is φ70 mm. The outer diameter is a constant φ70 mm from one end to the other. The distance (height) from one end to the other end is 30 mm. The inclination angle of the inner peripheral surface is 45 °. The coefficient of thermal expansion of the metal cylinder was 12.0 × ^10-6 / K.

[experimental method]
As shown in FIG. 8C, after fitting the outer peripheral surface of the ceramic member 1 assuming the ceramic member 52 to the inner peripheral surface of the metal cylinder assuming the turbine shroud 16, the ceramic member 1 is pressed with a pressure of 1 MPa. Fixed with. In this state, the temperature of the entire metal cylinder and ceramic member 1 was raised to 500 ° C. After the temperature was raised, the ceramic member 1 was inspected for peeling and cracking. A similar test was performed after the temperature had dropped to room temperature.

Similarly, after fitting the outer peripheral surface of the ceramic member 2 to the inner peripheral surface of the metal cylinder, the ceramic member 2 was fixed by pressing with a pressure of 10 MPa. In this state, the temperature of the entire metal cylinder and the ceramic member 2 was raised to 500 ° C. After the temperature was raised, the ceramic member 2 was inspected for peeling and cracking. A similar test was performed after the temperature had dropped to room temperature.

(Example 2)
A ceramic member 1 and a ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) were prepared from silicon nitride. That is, the ceramic member 1 and the ceramic member were the same as in Example 1 except that silicon nitride was used as a raw material, yttria and alumina were used as auxiliary agents, and resin was used as a pore-forming agent and fired at 1750 ° C. for 2 hours in a nitrogen atmosphere. 2 was prepared. Then, an experiment was conducted in the same manner as in Example 1.

(Example 3)
The experiment was carried out in the same manner as in Example 1 except that the inclination angles of the ceramic member 1, the ceramic member 2 and the metal cylinder were set to 10 °.

(Example 4)
Except for the fact that the ceramic member 1 and the ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) were made of silicon nitride and the inclination angles of the ceramic member 1, the ceramic member 2 and the metal cylinder were set to 10 °. The experiment was carried out in the same manner as in Example 1.

(Example 5)
The experiment was carried out in the same manner as in Example 1 except that the inclination angles of the ceramic member 1, the ceramic member 2 and the metal cylinder were set to 80 °.

(Example 6)
Except for the fact that the ceramic member 1 and the ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) were made of silicon nitride and the inclination angles of the ceramic member 1, the ceramic member 2 and the metal cylinder were set to 80 °. The experiment was carried out in the same manner as in Example 1.

(Example 7)
Ceramic member 1 and ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) are made of silicon nitride, the porosity of the ceramic member 1 and the ceramic member 2 is 30%, the ceramic member 1, the ceramic member 2 and The experiment was carried out in the same manner as in Example 1 except that the inclination angle of the metal cylinder was 80 °.

(Example 8)
Ceramic member 1 and ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) are made of silicon nitride, the porosity of the ceramic member 1 and the ceramic member 2 is 60%, the ceramic member 1, the ceramic member 2 and The experiment was carried out in the same manner as in Example 1 except that the inclination angle of the metal cylinder was 80 °.

(Example 9)
Ceramic member 1 and ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) are made of silicon nitride, the porosity of the ceramic member 1 and the ceramic member 2 is 60%, the ceramic member 1, the ceramic member 2 and The experiment was carried out in the same manner as in Example 1 except that the inclination angle of the metal cylinder was 88 °.

(Example 10)
Ceramic member 1 and ceramic member 2 (coefficient of thermal expansion 2.8 × ^10-6 / K) are made of silicon nitride, the porosity of the ceramic member 1 and the ceramic member 2 is 60%, the ceramic member 1, the ceramic member 2 and The experiment was carried out in the same manner as in Example 1 except that the inclination angle of the metal cylinder was 60 °.

(Example 11)
Ceramic member 1 and ceramic member 2 (coefficient of thermal expansion 4.5 × ^10-6 / K) were prepared from silicon carbide and silicon. That is, the ceramic member 1 and the ceramic member 2 were produced in the same manner as in Example 1 except that silicon carbide, silicon, and a resin as a pore-forming agent were used as raw materials and fired at 1430 ° C. for 2 hours in an argon atmosphere. Then, the experiment was carried out in the same manner as in Example 1 except that the porosity of the ceramic member 1 and the ceramic member 2 was 60%, and the inclination angles of the ceramic member 1, the ceramic member 2 and the metal cylinder were 80 °. ..

(Example 12)
Ceramic member 1 and ceramic member 2 (coefficient of thermal expansion 1.5 × 10 ^-6 / K) were prepared with cordierite. That is, the ceramic member 1 and the ceramic member 2 were formed in the same manner as in Example 1 except that talc, alumina, kaolin, silica, and a resin were used as raw materials and fired at 1420 ° C. for 2 hours in an air atmosphere. Made. Then, the experiment was carried out in the same manner as in Example 1 except that the porosity of the ceramic member 1 and the ceramic member 2 was 60%, and the inclination angles of the ceramic member 1, the ceramic member 2 and the metal cylinder were 80 °. ..

(Comparative Example 1)
As shown in FIG. 9A, the ceramic member 1 and the ceramic member 2 have an outer diameter of φ50 mm, which is constant from one end to the other end, and an inner diameter of φ10 mm, which is constant from one end to the other end. , A cylindrical shape with a height of 20 mm.

As shown in FIG. 9B, the outer diameter of the metal cylinder was set to a constant φ70 mm from one end to the other. The inner diameter was changed in two steps. That is, the inner diameter of the portion extending 10 mm from one end to the other end is φ10 mm, and the inner diameter of the portion extending 20 mm from the other end to one end is φ50 mm. The distance (height) from one end to the other end was set to 30 mm. That is, it has a structure in which a recess for inserting the ceramic member 1 or the ceramic member 2 is formed at the other end of the metal cylinder.

Then, as shown in FIG. 9C, the ceramic member 1 was fitted into the recess formed at the other end of the metal cylinder, and then the ceramic member 1 was fixed by pressing with a pressure of 10 MPa. In this state, the temperature of the entire metal cylinder and ceramic member 1 was raised to 500 ° C. After the temperature was raised, the ceramic member 1 was inspected for peeling and cracking. A similar test was performed after the temperature had dropped to room temperature. A similar experiment was performed on the ceramic member 2.

(Evaluation)
If the ceramic member 1 and the ceramic member 1 are not peeled or cracked after the temperature is raised, it is judged as "○", and if any one of the ceramic member 1 and the ceramic member 1 is peeled or cracked, it is judged as "x". It was judged. The breakdown of Examples 1 to 12 and Comparative Example 1 and the evaluation results are shown in Table 1 below.

From Table 1, the structure in which the ceramic member 1 and the ceramic member 2 assuming the ceramic member 52 are fitted to the inner peripheral surface of the metal cylinder assuming the turbine shroud 16, that is, in Examples 1 to 12, all are ceramics. No peeling or cracking of the member 1 and the ceramic member 2 occurred.

In the comparative example assuming the conventional configuration, both the ceramic member 1 and the ceramic member 2 were cracked.

It should be noted that the shroud structure and turbocharger according to the present invention are not limited to the above-described embodiments, and of course, various configurations can be adopted without departing from the gist of the present invention.

That is, in the above example, the shroud structure is applied to the turbine shroud 16 on the turbine side, which becomes hot, but it may be applied to the compressor shroud 24 (see FIG. 1) on the compressor side. The low temperature is about 200 ° C., which is higher than the room temperature (25 ° C.). Even in such an environment, by applying the shroud structure according to the present embodiment, the clearance between the ceramic member 52 installed in the compressor shroud 24 and the blade 22 of the compressor impeller 20 is constant regardless of the temperature change. Can be maintained, and the effect of suppressing a decrease in energy efficiency can be further enhanced.

In addition, it goes without saying that the structure of the shroud structure and the turbocharger according to the present invention can be diverted to the gas turbine.

Claims (14)

A shroud structure having a metal shroud (16) covering a blade (14) among impellers (12) that are rotationally driven by exhaust pressure.
With the shroud (16)
Among the shrouds (16), a ceramic member (52) attached at a position facing the blade (14) of the impeller (12), and
The pressing possess a member (54) pressed towards the ceramic member (52) in the shroud (16),
The shroud (16) has at least one first inclined surface (58) at a portion to which the ceramic member (52) is attached.
The ceramic member (52) has at least one second inclined surface (60) facing the first inclined surface (58) of the shroud (16).
In the ceramic member (52), the second inclined surface (60) is slidable along the first inclined surface (58) of the shroud (16) in response to pressing by the pressing member (54). shroud structure characterized by at. In the shroud structure according to claim 1 ,
The shroud structure, wherein the first inclined surface (58) and the second inclined surface (60) have the same angle (θ) with respect to the pressing direction by the pressing member (54). In the shroud structure according to claim 1 or 2 .
The first inclined surface (58) and the second inclined surface (60) are characterized in that they have an angle (θ) of more than 0 ° and less than 90 ° with respect to the pressing direction by the pressing member (54). Shroud structure to do. A shroud structure having a metal shroud (16) covering a blade (14) among impellers (12) that are rotationally driven by exhaust pressure.
With the shroud (16)
Among the shrouds (16), a ceramic member (52) attached at a position facing the blade (14) of the impeller (12), and
It has a pressing member (54) that presses the ceramic member (52) toward the shroud (16).
The pressing member (54)
Of the ceramic member (52), the exposed surface (56) that does not face the blade (14) of the impeller (12) is pressed against the blade (14).
The pressing member (54A) is
It has a metal member (62) that is in contact with the exposed surface (56) of the ceramic member (52) and is fixed to the shroud (16) in a low temperature portion.
The shroud structure is characterized in that the metal member (62) has a coefficient of thermal expansion higher than the coefficient of thermal expansion of the metal material constituting the shroud (16). In the shroud structure according to claim 4 ,
The shroud (16) is characterized by having a member (68) of the metal member (62) for fixing a surface of the ceramic member (52) opposite to the surface in contact with the exposed surface (56). Shroud structure. In the shroud structure according to claim 4 ,
The shroud (16) has a first overhang (70) that overhangs the metal member (62).
The metal member (62) has a second overhanging portion (76) that projects toward the shroud (16).
The pressing member (54B) further has a shroud structure having a clamp member (78) for fastening the tip end portion of the first overhanging portion (70) and the tip end portion of the second overhanging portion (76). body. In the shroud structure according to any one of claims 4 to 6 .
The shroud (16) has a plurality of first inclined surfaces (58).
The ceramic member (52) has a plurality of second inclined surfaces (60), and has a step (80) between the plurality of the second inclined surfaces (60).
The shroud structure is characterized in that the step (80) extends in a direction away from the exposed surface (56). A shroud structure having a metal shroud (16) covering a blade (14) among impellers (12) that are rotationally driven by exhaust pressure.
With the shroud (16)
Among the shrouds (16), a ceramic member (52) attached at a position facing the blade (14) of the impeller (12), and
It has a pressing member (54) that presses the ceramic member (52) toward the shroud (16).
The ceramic member (52) has a porosity of 1 to 80%.
The porosity of the ceramic member (52) is characterized in that the porosity of the portion facing the shroud (16) is lower than the porosity of the portion of the impeller (12) facing the blade (14). Structure. A shroud structure having a metal shroud (16) covering a blade (14) among impellers (12) that are rotationally driven by exhaust pressure.
With the shroud (16)
Among the shrouds (16), a ceramic member (52) attached at a position facing the blade (14) of the impeller (12), and
It has a pressing member (54) that presses the ceramic member (52) toward the shroud (16).
A shroud structure characterized in that a lubricant is interposed between the shroud (16) and the ceramic member (52). In the shroud structure according to any one of claims 1 to 9 .
A shroud structure characterized in that the pressing direction by the pressing member (54) is along the axial direction of the impeller (12) and away from the impeller (12). In the shroud structure according to any one of claims 1 to 9 .
A shroud structure characterized in that the pressing direction by the pressing member (54) is along the axial direction of the impeller (12) and toward the impeller (12). In the shroud structure according to any one of claims 1 to 11 .
A shroud structure characterized in that the coefficient of thermal expansion of the ceramic member (52) is 0.1 to 18.0 × ^10-6 / K. In a turbocharger having an impeller (12) rotationally driven by exhaust pressure and a metal shroud (16) covering the blade (14) of the impeller (12).
A turbocharger having the shroud structure according to any one of claims 1 to 12 . In the turbocharger according to claim 13 ,
The impeller (12) is a turbine impeller installed on the turbine side.
A turbocharger characterized in that the shroud (16) is a turbine shroud installed in a turbine.

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